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PubmedSumm118600 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: networks of molecular interactions are widely studied to reveal the complex roles played by genes , gene products and the cellular environments in biological processes . in these networks ( or graphs ) , the nodes represent genes or gene products and the edges represent specific interactions . in a protein dna network , an edge may represent the binding of a transcription factor to a promoter region , while in a protein protein physical interaction network it might represent a recorded evidence of co - immunoprecipitation or a two - hybrid interaction .
the nodes of the network are typically associated with additional information about the genes ( or gene products ) , such as positions in the chromosome ( or localization sites ) , or their gene ontology ( go ) classification . a number of specialized and publicly accessible databases are available , which contain data about the nodes [ the sgd database ( 1 ) ] and the interactions [ bind database ( 2 ) ] , and some databases contain information about both [ such as kegg ( 3 ) ] .
in addition , individual researchers often publish their data as part of their publications or project web sites .
currently , a number of analysis and visualization tools have been developed by different groups for assimilating , visualizing and for the analysis and modeling of these molecular interaction network data , of which the most notable are cytoscape ( 4 ) , osprey ( 5 ) , pathwayassist ( 6 ) , pathways database system ( 7 ) , genego ( ) , visant ( 8,9 ) .
yet another direction of effort is the storage and analysis of large - scale gene and protein expression data ( 1014 ) . while some of these store and display expression data , they do not allow query or analysis of such data or integration of novel gene expression data with existing network models .
ideally , an analysis tool for molecular interaction networks should enable a user to import , efficiently store , effectively retrieve and perform analysis on single genes , gene families , patterns of molecular interactions , as well as on the global structure of the network .
the tool needs to be sufficiently flexible for both micro - scale and macro - scale analysis using heterogenous data , and extract the data from a large number of disparate databases ; it should allow one to construct interaction networks by curation as well as computation [ e.g. using algorithms that convert a time - series microarray dataset into an influence network ( 15 ) ] ; it should enable the users to retrieve different interaction graphs through on - demand queries and construct new graphs by assembling them in a variety of ways .
it should also allow the incorporation of novel datasets locally , such as the user 's own microarray expression data , and/or overlay these on biological networks to explore novel relationships among genes .
these critical needs are the minimal requirements of a systems level analysis of biological pathways .
previously we reported a general - purpose scalable warehouse of biological information , pathsys ( 16 ) .
pathsys is a comprehensive data warehouse resulting from the integration of molecular interaction data with other graph - structured data , such as ontologies , e.g. go ( 17 ) and taxonomies , e.g. enzyme classification system and functional classification of yeast proteins ( 3 ) , and state data such as gene expression profiles , from over 20 curated and publicly contributed data sources , biological experimental and pubmed data for the eight representative organisms ( saccharomyces cerevisiae drosophila melanogaster , etc . for full list see website ) .
it contains more than 100 000 events of regulation , interaction and modification among genes , proteins , cell processes and small molecules .
here we present biologicalnetworks , the web - based query tool built on top of pathsys , and show how it enables a user to derive novel biological insights at the single gene level and functional relationships at the systems level .
pathsys 's data integration model achieves the following :
integration of object and property types from over 20 databases ( for a full list see the website ) , thus creating a controlled vocabulary ( ontology ) of object / attribute types.integration of nomenclature for genes / proteins . naming conventions between different datasets can be different , and the server - side parser translates between standard nomenclatures and an automated reconciliation procedure assigns multiple names as synonyms to the same orf.integration of different types of networks .
users can upload different types of interactions by specifying different evidence codes that are supported in the biologicalnetworks ( see software documentation for a full list of interaction types).to illustrate the novelty and capabilities of biologicalnetworks , in table 1 we compare biologicalnetworks against cytoscape and visant .
a limitation of cytoscape and visant is that the query capability of these systems is exactly the same as the graph - data manipulation and filtering capability visible on the interface .
thus , the visual integration tools do not have the capacity to take any combination of operations in any order and yet have the system retrieve the specified data in a fashion that optimizes memory and disk operations .
we have circumvented this limitation of visual integration by a database - level integration method using a query evaluation engine implementing a query algebra .
integration of object and property types from over 20 databases ( for a full list see the website ) , thus creating a controlled vocabulary ( ontology ) of object / attribute types .
naming conventions between different datasets can be different , and the server - side parser translates between standard nomenclatures and an automated reconciliation procedure assigns multiple names as synonyms to the same orf .
users can upload different types of interactions by specifying different evidence codes that are supported in the biologicalnetworks ( see software documentation for a full list of interaction types ) .
the nodes of the first type are reserved for genes , proteins , small molecules , cellular processes , etc .
the nodes of the second type ( controls ) represent events of functional regulation , chemical reactions or protein protein interactions ; they can have physical meaning , may denote general associations ; they can represent shared characteristics between components .
the nodes of the third type represent complex objects , such as macromolecular complexes , functional groups , pathways etc . in this case components
are made up of subcomponents , being compound or modular , and the connections between modular components ( or modules ) exist along with interconnections between their subcomponents . interactions in biologicalnetworks can also be defined as successively higher - level connections between groups of proteins , complexes , pathways or sub - networks .
most importantly , a classification scheme of property types representation ( about 2000 unique property types and 25 000 nodes of the property types tree ) allows biologicalnetworks to represent detailed micro - level information .
for example , a protein / process is not only localized in the nucleus , but it is represented as the starting point of finer subdivisions , such as within the nuclear membrane and ending in outer surface of the nuclear membrane as a
such a data model and integration environment align well with data representations of existing databases , such as bind ( 2 ) , kegg ( 3 ) , transpath ( 18 ) , emaze ( 19 ) and significantly extends the concepts of other tools , such as cytoscape and visant . to aid biological understanding ,
interaction networks and protein complexes can be viewed within the context of go ( 17 ) annotations or kegg ( 3 ) pathway assignments .
interactions have not only information about the relevant literature , but also the experimental system used and a rich array of details on the evidence and classification of the biological properties . for example , a genetic interaction between two genes may have information on the wild type / mutant forms ,
such a rich degree of annotation should play a vital role in understanding the nature of the interaction ( see manual for description ) .
an important goal of systems biology is to generate dynamical models of molecular interaction networks ( 20 ) . to enable this capability
this has been possible to achieve because of our representation of all three above objects as nodes in the interaction graph .
this allows the user to represent the process graphs in sbml ( 21 ) format for dynamical simulation using a variety of computational methods . to accompany biologicalnetworks
, we have developed a preliminary standard for exchanging files that have visual markup and annotation of network layouts .
users of biologicalnetworks can input several basic data types , including data in standardized network and interaction data exchange formats , such as psi - mi ( 22 ) , biopax ( ) and sbml ( 21 ) .
once a network dataset has been imported or loaded into biologicalnetworks , the genes or proteins within it can be queried for other known and predicted interactions from the pathsys 's database .
additionally , a repository of curated pathways ( 100 for s.cerevisiae and several hundreds from other organisms ) is available for analysis .
workspace , which can be annotated and saved for sharing inside user groups working with biologicalnetworks . to enable data analysis ,
the following tools are available : search : find and display a list of objects based on a name or a keyword .
expand : searches the database and displays objects functionally linked to a selected node or a set of nodes .
thus , by alternating expand and filtering options , users can browse through the database building their favorite pathways .
build pathways : finds a set of links between two or more nodes by searching for the shortest path in the total network of all links in the database .
find common targets / regulators : searches for common targets or regulators for the group of molecules .
this tool as well as build pathway can find functional links between proteins in the lists imported from other programs ( e.g. gene expression clusters ) .
find intersection with curated pathways : searches a group of nodes for other known and predicted interactions from the pathsys 's repository of curated pathways .
biologicalnetworks provides an advanced querying facility for retrieving the data of user 's interest by querying nodes and properties types .
user friendly querying interface allows user to make query with any logical combination of conditions both on node and property trees ( figure 1 , see user 's tutorial for details ) .
networks can also be analyzed for graph topological properties , such as degree distributions , path lengths , shortest paths or clustering coefficients .
expression data are easily imported through the import expression data wizard with a minimal amount of data preprocessing .
biologicalnetworks can interpret files of several types , including tab delimited ( stanford ) multiple sample format , the affymetrix file format , the tigr format and genepix file format .
the expression experiment viewer is designed to display a graphical representation of processed gene expression data .
it provides a workspace and a suite of algorithms for data analysis , sorting and searching , clustering and normalization , etc .
results of the clustering analysis are represented in the form of tables and heat maps , and graphically as expression graphs .
these viewers appear as a subtree under the analysis result within the main project properties tree .
functionalities available from microarray submenu and microarray experiment manager menu bar , allows the user to :
open an expression experiment in a form of a table and heat map;sort the experiment by a particular sample;expression data can be visually displayed on an existing pathway diagram by showing different shades of green / red depending on the fold change of expression;build pathways from expression values;build correlation networks ( e.g. pearson correlation);run go terms overrepresentation analysis ( fisher 's test ) on expression clusters , networks or group of genes .
open an expression experiment in a form of a table and heat map ; sort the experiment by a particular sample ; expression data can be visually displayed on an existing pathway diagram by showing different shades of green / red depending on the fold change of expression ; build pathways from expression values ; build correlation networks ( e.g. pearson correlation ) ; run go terms overrepresentation analysis ( fisher 's test ) on expression clusters , networks or group of genes . in figure 2 a sample pathway incorporating expression data from a microarray experiment has been assembled . on the left panel is a hierarchical tree of analysis workspace , where different types of microarray data as well as analysis and associated results can be accessed .
on the pathway diagram genes that are up - regulated in a particular experiment are shown in shades of red , while genes that are down - regulated are shown in shades of green ; if no match is found the color gray is used . using these data
it is now possible to provide further annotations of edge property such as positive or negative regulation or to provide new edges between nodes . in conclusion ,
the biologicalnetworks web server allows a systems level analysis of genomic scale information as well as single object queries over a variety of databases for integrative views of biological function and for hypothesis generation .
pathsys 's data integration model achieves the following :
integration of object and property types from over 20 databases ( for a full list see the website ) , thus creating a controlled vocabulary ( ontology ) of object / attribute types.integration of nomenclature for genes / proteins . naming conventions between different datasets can be different , and the server - side parser translates between standard nomenclatures and an automated reconciliation procedure assigns multiple names as synonyms to the same orf.integration of different types of networks .
users can upload different types of interactions by specifying different evidence codes that are supported in the biologicalnetworks ( see software documentation for a full list of interaction types).to illustrate the novelty and capabilities of biologicalnetworks , in table 1 we compare biologicalnetworks against cytoscape and visant .
a limitation of cytoscape and visant is that the query capability of these systems is exactly the same as the graph - data manipulation and filtering capability visible on the interface .
thus , the visual integration tools do not have the capacity to take any combination of operations in any order and yet have the system retrieve the specified data in a fashion that optimizes memory and disk operations .
we have circumvented this limitation of visual integration by a database - level integration method using a query evaluation engine implementing a query algebra .
integration of object and property types from over 20 databases ( for a full list see the website ) , thus creating a controlled vocabulary ( ontology ) of object / attribute types .
integration of nomenclature for genes / proteins . naming conventions between different datasets can be different , and the server - side parser translates between standard nomenclatures and an automated reconciliation procedure assigns multiple names as synonyms to the same orf .
users can upload different types of interactions by specifying different evidence codes that are supported in the biologicalnetworks ( see software documentation for a full list of interaction types ) .
the nodes of the first type are reserved for genes , proteins , small molecules , cellular processes , etc .
the nodes of the second type ( controls ) represent events of functional regulation , chemical reactions or protein protein interactions ; they can have physical meaning , may denote general associations ; they can represent shared characteristics between components .
the nodes of the third type represent complex objects , such as macromolecular complexes , functional groups , pathways etc . in this case components
are made up of subcomponents , being compound or modular , and the connections between modular components ( or modules ) exist along with interconnections between their subcomponents .
interactions in biologicalnetworks can also be defined as successively higher - level connections between groups of proteins , complexes , pathways or sub - networks .
most importantly , a classification scheme of property types representation ( about 2000 unique property types and 25 000 nodes of the property types tree ) allows biologicalnetworks to represent detailed micro - level information .
for example , a protein / process is not only localized in the nucleus , but it is represented as the starting point of finer subdivisions , such as within the nuclear membrane and ending in outer surface of the nuclear membrane as a component or as simply
such a data model and integration environment align well with data representations of existing databases , such as bind ( 2 ) , kegg ( 3 ) , transpath ( 18 ) , emaze ( 19 ) and significantly extends the concepts of other tools , such as cytoscape and visant . to aid biological understanding ,
interaction networks and protein complexes can be viewed within the context of go ( 17 ) annotations or kegg ( 3 ) pathway assignments .
interactions have not only information about the relevant literature , but also the experimental system used and a rich array of details on the evidence and classification of the biological properties . for example , a genetic interaction between two genes may have information on the wild type / mutant forms , phenotype ( invasiveness , etc . ) , mutant
such a rich degree of annotation should play a vital role in understanding the nature of the interaction ( see manual for description ) . an important goal of systems biology is to generate dynamical models of molecular interaction networks ( 20 ) . to enable this capability
this has been possible to achieve because of our representation of all three above objects as nodes in the interaction graph .
this allows the user to represent the process graphs in sbml ( 21 ) format for dynamical simulation using a variety of computational methods . to accompany biologicalnetworks
, we have developed a preliminary standard for exchanging files that have visual markup and annotation of network layouts .
users of biologicalnetworks can input several basic data types , including data in standardized network and interaction data exchange formats , such as psi - mi ( 22 ) , biopax ( ) and sbml ( 21 ) .
once a network dataset has been imported or loaded into biologicalnetworks , the genes or proteins within it can be queried for other known and predicted interactions from the pathsys 's database . additionally , a repository of curated pathways ( 100 for s.cerevisiae and several hundreds from other organisms ) is available for analysis .
workspace , which can be annotated and saved for sharing inside user groups working with biologicalnetworks .
to enable data analysis , the following tools are available : search : find and display a list of objects based on a name or a keyword .
expand : searches the database and displays objects functionally linked to a selected node or a set of nodes .
thus , by alternating expand and filtering options , users can browse through the database building their favorite pathways .
build pathways : finds a set of links between two or more nodes by searching for the shortest path in the total network of all links in the database .
find common targets / regulators : searches for common targets or regulators for the group of molecules .
this tool as well as build pathway can find functional links between proteins in the lists imported from other programs ( e.g. gene expression clusters ) .
find intersection with curated pathways : searches a group of nodes for other known and predicted interactions from the pathsys 's repository of curated pathways .
biologicalnetworks provides an advanced querying facility for retrieving the data of user 's interest by querying nodes and properties types .
user friendly querying interface allows user to make query with any logical combination of conditions both on node and property trees ( figure 1 , see user 's tutorial for details ) .
networks can also be analyzed for graph topological properties , such as degree distributions , path lengths , shortest paths or clustering coefficients .
expression data are easily imported through the import expression data wizard with a minimal amount of data preprocessing .
biologicalnetworks can interpret files of several types , including tab delimited ( stanford ) multiple sample format , the affymetrix file format , the tigr format and genepix file format .
the expression experiment viewer is designed to display a graphical representation of processed gene expression data .
it provides a workspace and a suite of algorithms for data analysis , sorting and searching , clustering and normalization , etc .
results of the clustering analysis are represented in the form of tables and heat maps , and graphically as expression graphs .
these viewers appear as a subtree under the analysis result within the main project properties tree .
functionalities available from microarray submenu and microarray experiment manager menu bar , allows the user to :
open an expression experiment in a form of a table and heat map;sort the experiment by a particular sample;expression data can be visually displayed on an existing pathway diagram by showing different shades of green / red depending on the fold change of expression;build pathways from expression values;build correlation networks ( e.g. pearson correlation);run go terms overrepresentation analysis ( fisher 's test ) on expression clusters , networks or group of genes .
open an expression experiment in a form of a table and heat map ; sort the experiment by a particular sample ; expression data can be visually displayed on an existing pathway diagram by showing different shades of green / red depending on the fold change of expression ; build pathways from expression values ; build correlation networks ( e.g. pearson correlation ) ; run go terms overrepresentation analysis ( fisher 's test ) on expression clusters , networks or group of genes . in figure 2
on the left panel is a hierarchical tree of analysis workspace , where different types of microarray data as well as analysis and associated results can be accessed . on the pathway diagram genes that are up - regulated in a particular experiment
are shown in shades of red , while genes that are down - regulated are shown in shades of green ; if no match is found the color gray is used . using these data
it is now possible to provide further annotations of edge property such as positive or negative regulation or to provide new edges between nodes . in conclusion
, the biologicalnetworks web server allows a systems level analysis of genomic scale information as well as single object queries over a variety of databases for integrative views of biological function and for hypothesis generation .
Output:
| systems level investigation of genomic scale information requires the development of truly integrated databases dealing with heterogeneous data , which can be queried for simple properties of genes or other database objects as well as for complex network level properties , for the analysis and modelling of complex biological processes . towards that goal , we recently constructed pathsys , a data integration platform for systems biology , which provides dynamic integration over a diverse set of databases [ baitaluk et al .
( 2006 ) bmc bioinformatics 7 , 55 ] . here
we describe a server , biologicalnetworks , which provides visualization , analysis services and an information management framework over pathsys .
the server allows easy retrieval , construction and visualization of complex biological networks , including genome - scale integrated networks of protein protein , protein dna and genetic interactions .
most importantly , biologicalnetworks addresses the need for systematic presentation and analysis of high - throughput expression data by mapping and analysis of expression profiles of genes or proteins simultaneously on to regulatory , metabolic and cellular networks .
biologicalnetworks server is available at . |
PubmedSumm118601 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: acetabular orientation refers to the direction of the acetabular cup relative to the axial and coronal planes .
this is an important factor in the determination of the appropriate type and extent of operations on the hips , such as an osteotomy of the pelvis in development dysplasia of the hip ( ddh ) , or total hip arthroplasty for osteoarthritis or trauma to the acetabulum .
some investigators have developed methods to evaluate the acetabular orientation , including x - ray examination , computed tomography ( ct ) , and magnetic resonance imaging ( mri ) .
when evaluating acetabular orientation , 2 important angles are widely used , including the acetabular anteversion angle ( aaa ) and the acetabular inclination angle ( aia ) .
they were measured on cadavers , x - ray films , 2-dimensional ct images , mri , and 3-dimensional ct reconstruction systems .
on ct imaging , the aaa is formed by a reference line perpendicular to the line connecting the posterior iliums and a line connecting the posterior and anterior margins of the acetabulum .
the aia is the angle between the face of the acetabular cup and the transverse axis .
however , there are still some shortcomings because the cartilage of the acetabulum and the femoral head can not be distinguished on ct and the information regarding the cartilaginous acetabulum is lost . in recent years , more and more studies focusing on mri evaluation of acetabular orientation are being reported .
mri overcomes the shortcomings of ct , since it shows the cartilage and bone more clearly and may provide more useful information than does ct when evaluating acetabular orientation .
douira - khomsi et al conducted a prospective study about mri evaluation of acetabular residual dysplasia in ddh , they demonstrated that mri promoted more accurate selection of patients for pelvic osteotomy and aided in the choice of the most appropriate type of osteotomy .
unfortunately , there are no mri data regarding the measurement of aaa and aia in normal children , making it difficult to differentiate normal from abnormal hips .
our study aims to investigate the change of aaa and aia with age in normal chinese children .
a retrospective study of the medical records of children in our hospital who underwent mri examination ( including the hip joint ) from january 2009 to december 2015 was performed .
this study was approved by the ethical committee of guangzhou women and children 's medical center ( no .
2015020904 ) . generally , these patients underwent mri examination because of diseases pertaining to proximal femur or pelvis , or lower limb pain , or congenital abnormality of the urogenital system .
the patients with a normal mri reading of the hip joint or diagnosis of mild synovitis of the hip were included in this study .
we excluded the patients with nonstandard positioning during mri examination or with other diseases of the hip such as femoral head necrosis , ddh , septic arthritis of the hip , fractures of acetabulum or femoral neck , or tuberculosis of the hip .
a total of 180 patients ( 81 girls and 99 boys ) aged from 6 months to 16 years met our criteria for this study and were eligible for final analysis .
mri examination was performed using a 1.5 t philips gyroscan achieva mri system ( philips , best , the netherlands ) with the standard examination including the whole pelvis and proximal femur with axial , sagittal , and coronal plane sequences .
the mri examination was carried out under sedation or general anesthesia with the patients placed supine , legs in a neutral position , and with a body array coil placed anterior and posterior to the pelvis .
the sequences included t1-weighted ( t1-w ) spin - echo ( se ) images ( repetition time / echo time [ tr / te ] 372/7 milliseconds ; time of acquisition 4 minutes 28 seconds ) in the coronal and sagittal planes and t2-weighted ( t2-w ) fast field - echo ( ffe ) ( repetition time 369 milliseconds ; echo time 14 milliseconds ; time of acquisition 3 minutes 16 seconds ; flip angle 25 ) in coronal and sagittal planes .
all sequences used a 22 cm field of view , 3 mm slice thickness , 0.4 mm slice gap , 384 - 384 matrix , and 2 for the number of excitations . using the mri images ,
the following bony and cartilage parameters were measured : the aaa , aia , the acetabular index ( ai ) , the axial section total femoral head coverage angle ( a - tca ) , and the coronal section total femoral head coverage angle ( c - tca ) .
the angles of a - tca and c - tca are parameters of the relationship of acetabulum and femoral head ; as the angle increases , the femoral head is covered by the acetabulum to a larger extent .
the method to measure aaa and aia were similar to the methods used for ct by stem et al .
for measuring bony angles , we used the bony margins of the acetabulum , whereas for cartilage angles , we used the cartilage margins of the acetabulum . figures 1 and 2
show the method . on t1-w se sequences in the axial plane , at the level of the center of the hip joint ( with a largest femoral head diameter or deepest point of the acetabulum ) , aaa was measured as the angle formed by a reference line perpendicular to a line connecting the posterior iliac wings or triradiate cartilage and a line connecting the posterior and anterior margins of the acetabulum .
the a - tca is formed by 2 lines connecting the center of the femoral head to the posterior and anterior margins of the acetabulum .
on t2-w ffe sequences in the coronal plane at the level of the center of the hip joint ( using images with the largest femoral head diameter or greatest depth of the acetabulum ) , the aia was measured as the angle formed by a reference line connecting the triradiate cartilage and a line connecting the superior and inferior margins of the acetabulum .
the ai was measured as the angle formed by the same reference line connecting the triradiate cartilages and a line connecting the center of the acetabulum and the superior acetabulum .
the c - tca is formed by the 2 lines connecting the center of the femoral head to the superior and inferior margins of the acetabulum . the measurement of bony and cartilage acetabular anteversion angle and axial section total femoral head coverage angle on axial section imaging of magnetic resonance imaging in an 8-year - old male .
the measurement of bony and cartilage acetabular inclination angle , acetabular index , and coronal section total femoral head coverage angle on coronal section imaging of magnetic resonance imaging in a 6-year - old male .
two persons ( orthopedic doctors ) measured these angles independently , and both of them were trained by a radiologist in our hospital before measuring , to make sure all measurements were accurate and repeatable . paired t tests
were used to compare the difference between 2 measurers , differences between bony and cartilage angles , as well as the difference between the values of left and right side .
one - way analysis of variance ( anova ) and multiple comparisons were used to compare the angles among the different age groups .
we show the results of the measurements of acetabular orientation angles in tables 1 and 2 .
sample means of bony aaa , aia , ai , a - tca , and c - tca in different age groups ( n = 180 ) .
sample means of cartilage aaa , aia , ai , a - tca , and c - tca in different age groups ( n = 180 ) .
interobserver agreement was high between the 2 orthopedic surgeons ( p = 0.352 ) .
. there were no differences ( p = 0.503 ) between the left and right side , and thus we combined the data and used the sample mean values .
there was no difference between male and female in bony and cartilage aaa , aia , ai , a - tca , and c - tca ( p > 0.05 ) .
the sample means of the bony aaa in the 6-month age group and the 14- to 16-year age group were 12.3 0.9 and 13.8 1.8 , respectively .
the total sample mean bony aaa was 12.2 2.5 , and there was no significant ( n.s . )
difference among the 14 different age groups ( p = 0.169 ) with analysis of variance .
the sample means of the bony aia in the 6-month age group and in the 14- to 16-year age group were 51.1 2.1 and 49.8 3.5 , respectively .
the total sample mean bony aia was 50.9 2.5 ; again there was no difference between the 14 age groups ( p = 0.103 ) .
the mean bony ai decreased significantly with age ( p < 0.01 ) .
the mean bony ai in the 6-month age group was 24.1 2.4 , decreasing to 12.5 2.3 in the 12- to 13-year age group .
the total sample mean cartilage aaa was 12.1 2.5 and there were n.s .
similar results were found for the cartilage aia ( p = 0.272 ) and cartilage ai ( p = 0.627 ) .
the total sample means of the cartilage aia and ai were 41.2 3.8 and 5.9 1.7 , respectively .
these results indicated that both cartilage aaa , aia , and ai remained unchanged with age .
no differences were found between bony and cartilage aaa ( p = 0.250 ) ; however , bony aia was significantly larger than cartilage aia ( p < 0.001 ) .
the bony a - tca and c - tca significantly change with age ( p < 0.001 ) .
the mean bony a - tca at 6 months was 117.0 5.8 , increasing to 144.5 4.6 in the 14- to 16-year age group .
the mean c - tca at 6 months was 127.5 5.1 , increasing to 140.7 2.5 at 14- to 16-year age group .
no differences were found in a - tca between the 6-month , 1- , 2- , 3- , 4- , and 5-year age groups ( n.s . ) .
however , the a - tca in the 6-month , 1- , 2- , 3- , and 4-year age groups were significantly lower than the a - tca in the remaining groups , and similar results were found for age - specific c - tca values .
the total sample means of cartilage a - tca and c - tca were 145.2 7.2 and 154.1 5.7 , both of them remained unchanged with age ( n.s . ) . in the 14- to 16-year age group ,
cartilage c - tca was significantly larger than bony c - tca ( p < 0.001 ) .
however , cartilage a - tca was similar when compared to bony a - tca ( p = 0.599 ) .
figures 3 and 4 are the comparisons of 0.5- and 12-year - old patients on bony and cartilage aaa , aia , ai , a - tca , and c - tca
comparisons of 0.5- and 12-year - old patients on bony acetabular anteversion angle , acetabular inclination angle , acetabular index , axial section total femoral head coverage angle , and coronal section total femoral head coverage angle .
comparisons of 0.5- and 12-year - old patients on cartilage acetabular anteversion angle , acetabular inclination angle , acetabular index , axial section total femoral head coverage angle , and coronal section total femoral head coverage angle .
they are the same patients of fig . 3 , and both of them are males .
the sample means of the bony aaa in the 6-month age group and the 14- to 16-year age group were 12.3 0.9 and 13.8 1.8 , respectively .
the total sample mean bony aaa was 12.2 2.5 , and there was no significant ( n.s . )
difference among the 14 different age groups ( p = 0.169 ) with analysis of variance .
the sample means of the bony aia in the 6-month age group and in the 14- to 16-year age group were 51.1 2.1 and 49.8 3.5 , respectively .
the total sample mean bony aia was 50.9 2.5 ; again there was no difference between the 14 age groups ( p = 0.103 ) .
the mean bony ai decreased significantly with age ( p < 0.01 ) .
the mean bony ai in the 6-month age group was 24.1 2.4 , decreasing to 12.5 2.3 in the 12- to 13-year age group .
the total sample mean cartilage aaa was 12.1 2.5 and there were n.s .
similar results were found for the cartilage aia ( p = 0.272 ) and cartilage ai ( p = 0.627 ) .
the total sample means of the cartilage aia and ai were 41.2 3.8 and 5.9 1.7 , respectively .
these results indicated that both cartilage aaa , aia , and ai remained unchanged with age .
no differences were found between bony and cartilage aaa ( p = 0.250 ) ; however , bony aia was significantly larger than cartilage aia ( p < 0.001 ) .
the bony a - tca and c - tca significantly change with age ( p < 0.001 ) .
the mean bony a - tca at 6 months was 117.0 5.8 , increasing to 144.5 4.6 in the 14- to 16-year age group .
the mean c - tca at 6 months was 127.5 5.1 , increasing to 140.7 2.5 at 14- to 16-year age group .
no differences were found in a - tca between the 6-month , 1- , 2- , 3- , 4- , and 5-year age groups ( n.s . ) .
however , the a - tca in the 6-month , 1- , 2- , 3- , and 4-year age groups were significantly lower than the a - tca in the remaining groups , and similar results were found for age - specific c - tca values .
the total sample means of cartilage a - tca and c - tca were 145.2 7.2 and 154.1 5.7 , both of them remained unchanged with age ( n.s . ) . in the 14- to 16-year age group ,
cartilage c - tca was significantly larger than bony c - tca ( p < 0.001 ) .
however , cartilage a - tca was similar when compared to bony a - tca ( p = 0.599 ) .
figures 3 and 4 are the comparisons of 0.5- and 12-year - old patients on bony and cartilage aaa , aia , ai , a - tca , and c - tca .
comparisons of 0.5- and 12-year - old patients on bony acetabular anteversion angle , acetabular inclination angle , acetabular index , axial section total femoral head coverage angle , and coronal section total femoral head coverage angle .
comparisons of 0.5- and 12-year - old patients on cartilage acetabular anteversion angle , acetabular inclination angle , acetabular index , axial section total femoral head coverage angle , and coronal section total femoral head coverage angle .
they are the same patients of fig . 3 , and both of them are males .
in this study , we investigated the changes of acetabular orientation using mri in children .
this is not a cross - sectional population study , and thus there is potential bias in the selection of patients .
we believe that our study is the first to measure the acetabular orientation on mri in normal children during the course of skeletal maturation .
the results of our study provide important information in understanding the normal growth of the hip joint and the variation between individuals .
it will assist us to evaluate the hip with what appears to be an abnormal acetabular anteversion and acetabular inclination on bony and cartilage .
in addition , it will also help us to make operation plans pertaining to the hip , providing more accurate information for the selection of patients for pelvic osteotomy and the choice of the most appropriate type of osteotomy . in our study ,
the overall sample mean bony and cartilage aaa were 12.2 and 12.1 , respectively , and both of them did not change among different age groups in normal chinese children .
so far , few studies have been conducted on the acetabular orientation in normal children .
mckibbin measured the aaa on 15 pelvises from fresh infant cadavers , and their sample means for the aaa in normal male and female neonatal hips were 6 and 9 , respectively .
jacquemier et al measured the aaa on ct scans in 143 normal children aged from 1 to 15 years and reported a mean aaa of 13 which remained constant during growth .
our bony and cartilage aaa measurements agree well with those reported by jacquemier et al and weiner et al , but differ from those reported by mckibbin .
the mean bony and cartilage aaa measured in our sample of children at 6 months were 12.3 and 13.6 on mri , respectively .
in addition , no differences were observed between the 6-month and the 1- or 2-year age groups .
first , in the study of mckibbin , they measured aaa on cadavers . although it may reflect the cartilaginous aaa as measured in our study , it probably may be different from an aaa measured by either ct or mri .
in addition , mckibbin measured aaa on fresh newborn cadavers ( died within the first 2 weeks of life ) .
their measurements may be different from our measured aaa at the age of about 6 months .
although we did not measure the bony aaa in patients older than 16 years , some studies indicated a significantly increased bony aaa in adults ( table 3 ) .
furthermore , our results are more similar to the results of jacquemier et al and weiner et al , indicating that there is probably no difference between chinese children and other ethnicities regarding aaa .
our study also showed that the bony and cartilage aia remained constant during skeletal maturation in normal chinese children until 14 to 16 years of age .
the mean bony and cartilage aia in our sample of apparently normal children were 50.9 and 41.2 on mri , respectively .
to our knowledge , there are no studies focusing on aia in normal children using mri measurements . however , there are some studies reporting on the bony aia in adults by other imaging methods . in the study by stem
et al , the mean aia in their adult sample was 39. suo et al evaluated acetabular orientation on x - ray films of 40 hips , and the average aia was 44.1. in a study by fukui et al , 25 cadavers ( 31 hips ) were used to examine the orientation of the cup component aligned with the transverse acetabulum ligament .
the average radiographic aia was 43.5. the mean bony aia in our sample of apparently normal children was 50.9 and somewhat larger than the results reported by fukui et al , but the cartilage aia in our study ( 41.2 ) is similar to them . considering the adult studies mentioned , we hypothesize that there may be a continued decrease in the aia after skeletal maturity , this may be attributed to the ossification of acetabular cartilage at the outer margin of acetabulum , and therefore the final bony aia resembles the cartilage aia .
our study also indicates that cartilage ai remains unchanged with age , but the bony ai decreases with age , in similarity to the results of other studies . in the study of huber
et al , who analyzed 115 hips , the bony ai decreased until the age group of 4 to 6 years and then remained relatively constant around 15 , and the cartilage ai ( around 5 ) stayed relatively constant until the age of 13 years .
tonnis measured the ai on x - ray films in a large number of normal hips , and the mean ai was about 30 at the time of birth and 15 at the age of 5 to 7 years .
shi et al measured the ai on 2333 apparently normal x - ray films of the pelvis , and the mean ai was 28.39 in the newborn period and 12.80 at the age of 10 years . in our study , the bony ai measured by mri in normal children at the age of 6 months was 24.1 and decreased to 12.5 in the 12- to 13-year - old age group , in agreement with the results of tonnis and shi . some factors may contribute to the stable value of the aaa and the aia in our sample of children .
the acetabulum is formed by 3 bones : ilium ( superiorly ) , ischium ( inferiorly ) , and pubis ( anteriorly ) .
the triradiate cartilage is the center of the acetabulum and connects the 3 bones , subsequently forming the acetabular cup .
the growth of acetabulum is closely associated with the process of enchondral ossification in the acetabulum .
it has been demonstrated that biomechanical loading regulates enchondral ossification , and thus biomechanical factors play a role in the development of acetabulum , including acetabular orientation . in normal hips
, there is a congruent relationship of the acetabulum with the femoral head , and compressive stress is distributed across the acetabulum during endochondal ossification .
this may lead to a very balanced growth of ilium , ischium , and pubis within the cartilaginous acetabulum which maintains a stable acetabular orientation .
their results indicated that changes in the ossification of the acetabular anterior and posterior walls were minimal and resulted in only minor variations in acetabular anteversion with growth .
we believe that the ossification of the acetabular labral cartilage may account for the changes that appear to occur in the aaa and aia after skeletal maturity .
our study showed that the bony femoral head coverage increased with age , but the cartilage femoral head coverage remained unchanged from 6 months to 16 years of age .
generally , as the acetabulum is growing , the cup becomes larger in diameter and deepens , and a larger portion of the femoral head is thus covered by the acetabulum .
however , this increase of coverage area may not change the rate of femoral head coverage . from our study
, we consider that the increase of bony femoral head coverage rate may be attributed to the ossification of the acetabular cartilage at the acetabulum margin , as the bony a - tca at 14 to 16 years ( 144.5 ) was similar to cartilage a - tca ( 145.2 ) .
interestingly , our study also indicated that the bony femoral head coverage angles ( a - tca and c - tca ) remained stable until 4 to 5 years of age , but significantly increased with age afterward .
although the patients with a normal mri reading of the hip joint were included , they were not healthy children and had diseases pertaining to proximal femur or pelvis , or lower limb pain , or congenital abnormality of the urogenital system .
in fact , it would be more clear if measured on t2-w ffe . both of them might influence the results of measurements .
we found a mean bony and cartilage aaa of 12.2 2.5 and 12.1 2.5 ; and a mean bony and cartilage aia of 50.9 2.5 and 41.2 3.8 in an apparently normal sample of 180 chinese children .
the bony coverage of the femoral head by the acetabulum increases with age , but the cartilage coverage of the femoral head remains stable up to 14 to 16 year of age .
Output:
| abstractthere are no data regarding the acetabular orientation on magnetic resonance imaging ( mri ) ; this study investigates the changes of acetabular orientation with age in normal chinese children.we retrospectively analyzed the medical records of children who underwent hip mri examination at our hospital from january 2009 to december 2015 .
a total of 180 patients with normal mri reading of the hip joints were included and were divided into 14 groups according to age : from 6 months of age and then for each year from 1 to 16 years .
the bony and cartilage acetabular anteversion angle ( aaa ) , acetabular inclination angle ( aia ) , and acetabular index ( ai ) were measured .
total bony and cartilage femoral head coverage angles were measured on axial section total femoral head coverage angle ( a - tca ) and coronal section total femoral head coverage angle ( c - tca).the mean bony aaa and aia were 12.2 2.5 and 50.9 2.5 , respectively ; both of them stayed constant from the age of 6 months to 16 years .
similar results were found in cartilage aaa ( 12.1 2.5 ) and aia ( 41.2 3.0 ) .
there was no difference between bony and cartilage aaa , but bony aia was significantly larger than cartilage aia .
bony ai was 24.1 2.4 at the age of 6 months , decreasing to 12.5 2.3 by 12 to 13 years of age ; cartilage ai ( 5.9 1.7 ) maintained a steady value with age .
the mean bony a - tca and c - tca at 6 months were 117.0 5.8 and 127.5 5.1 , increasing to 144.5 4.6 and 140.7 2.5 at the age of 16 years .
however , the cartilage a - tca ( 145.2 7.2 ) and c - tca ( 154.1 5.7 ) did not change significantly with age.both bony and cartilage aaa and aia remain constant up to the age of 16 years in normal chinese pediatric population . although the cartilage coverage of femoral head by the acetabulum remains unchanged with age , the bony coverage of femoral head increases . |
PubmedSumm118602 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: tangential to the cortical surface , representations of the sensory periphery are organized into well - ordered maps .
the most intensely studied example is the primary visual cortex , which is arranged with superimposed maps of retinotopy , ocular dominance and orientation ( bonhoeffer and grinvald , 1991 ) .
other prominent cortical maps are the tonotopic organization of auditory cortex ( kalatsky et al . , 2005 ) , taste maps in gustatory cortex ( accolla et al . , 2007 ) and somatotopic maps in primary somatosensory cortex ( kaas , 1991 ) .
mapping functionally related sensory information onto nearby cortical regions is thought to minimize axonal wiring length and simplify the synaptic circuits underlying correlation - based associational plasticity .
normal to the cortical surface , the neocortex can be divided into distinct layers containing various classes of neurons , each contributing differently to cortical computation ( krupa et al . , 2004 ) . in primary sensory cortices ,
information from the periphery arrives primarily from the thalamic innervation of layer 4 , also known as the granular cell layer .
cortical layers 1 , 2 and 3 form the superficial layers , also known as the supragranular layers , which are likely the most integrative layers , gathering sensory information and distributing output to other cortical areas .
the deep layers 5 and 6 form the output layers of the neocortex , innervating both subcortical and cortical areas . anatomical and electrophysiological studies have begun to shed light on the synaptic architecture of cortical microcircuits ( binzegger et al . , 2004 ;
the next obvious step is to relate the wiring diagram of these neuronal networks to their functional operation .
this is a difficult challenge , but the mouse barrel cortex offers promising avenues for future quantitative research .
the extensive array of mystacial vibrissae under active motor control serves as a sensitive tactile organ , which can provide information relating to the structure of the immediate surroundings ( kleinfeld et al . , 2006 ;
a surprisingly large part of the mouse brain is concerned with processing sensorimotor information relating to these whiskers on the snout ( figure 1a ) .
a remarkably high degree of organization is obvious in the primary somatosensory cortex , in which a clear pattern of cytoarchitectonic units termed
barrels are observed in perfect match with the arrangement of the whiskers on the snout of the mouse ( woolsey and van der loos , 1970 ) ( figure 1b ) .
these somatotopically arranged barrels are found exclusively in neocortical layer 4 ( figure 1c ) , and are likely formed during development through the patterned innervation of thalamocortical axons from the ventral posterior medial nucleus .
much of the cortical circuitry is arranged in a columnar fashion extending above and below the layer 4 barrel , and this defines a cortical barrel column ( petersen and sakmann , 2001 ; shepherd et al . , 2003 ) .
information relating to deflection of an individual whisker is processed primarily within the homologous barrel column
. however , there is also clear evidence for important lateral interactions , as found through examination of long - range axonal projections in supragranular and infragranular layers and through the broad subthreshold receptive fields ( brecht , 2007 ; petersen , 2007 ) . the barrel cortex .
( a ) an impressive array of whiskers on the snout of the rodent sends sensory information to the primary somatosensory barrel cortex ( s1 ) via the brainstem and the thalamus .
the barrel cortex signals to motor cortex ( m1 ) , which in turn regulates whisker movements .
active processing of tactile whisker information therefore appears to be an important feature of this sensory pathway .
( b ) the layout of the whiskers ( left ) is precisely matched by the layout of the barrels ( right ) in primary somatosensory cortex . mice and rats have the same layout of whiskers and a standard nomenclature has been developed .
single whisker sensory information from ventral posterior medial ( vpm ) thalamus arrives predominantly in a single layer 4 barrel . the supragranular layer 2/3 and the infragranular layers 5/6 are thought to perform integrative functions . modified and reproduced with permission from petersen ( 2007 ) .
copyright from neuron , cell press . in order to simplify experimental data and its interpretation ,
many researchers have found it useful to concentrate on the sensory information available from just a single whisker , by trimming all other whiskers . under these conditions it is possible to quantify the detailed kinetics of whisker movements and the precise moment when an individual whisker touches an object and correlate this information with cortical sensory processing ( crochet and petersen , 2006 ; ferezou et al . , 2006 , 2007 ) .
rodents with a single whisker can perform a number of whisker - dependent tasks , the best known of which is the gap - crossing task ( hutson and masterton , 1986 ) . in this behaviour ,
the rodent is placed on one elevated platform from which it has to reach across and jump to a target platform where a reward is located .
the rodents are forced to use their whisker to locate the target platform by performing the experiments in darkness and making the gap so large that the nose and paw can not reach across .
this behaviour depends upon the operation of the barrel cortex ( hutson and masterton , 1986 ) .
further experimental evidence suggests that at least part of the associational learning of this single whisker mediated behaviour may take place within the homologous cortical column ( harris et al . , 1999 ) .
because defined barrel columns can be reliably identified between animals , it seems likely that a great deal can be learned from detailed investigation of the synaptic circuits underlying a single cortical barrel column .
however , this information must be integrated with data relating to synaptic interactions with other cortical and subcortical brain areas and with data about the physiological activity of the underlying neuronal networks during learning and behaviour . the growing body of quantitative data relating synaptic circuits in the barrel cortex to functional activation ( sarid et al . , 2007 ) may thus lead to significant progress in our understanding of the synaptic mechanisms underlying sensory perception . in order to fully exploit the barrel cortex as a model system for active sensory processing , we need to be able to make precise manipulations in neurons of a defined barrel column .
recent advances in genetic manipulations of mice provide increasing levels of sophistication in spatiotemporal regulation of gene expression in specific cells localized to defined regions of the brain .
the genetic identification of molecular pathways underlying different aspects of cortical functional organization is also likely to lead to new therapeutic targets . since the first genetic studies of the barrelless mutation ( welker et al . , 1996 ) , many further genes have been identified as critical for barrel cortex formation .
however , genetic lesions often affect many brain areas since the gene products are widely expressed and may also alter brain development . under such conditions , it is difficult to attribute specific functions to individual genes .
the development of systems for spatiotemporally controlled knockout of genes has therefore been crucial in the field of molecular neurobiology .
the first breakthrough , developed by the tonegawa laboratory , came with the application of the cre loxp system to the brain . in their landmark papers , tsien et al .
( 1996a , b ) described a method to specifically remove nmda receptors from the ca1 region of the hippocampus , while leaving nmda receptors functional in all other brain regions .
one mouse line was generated by gene targeting strategies to insert loxp sites surrounding the second half of the nmda receptor 1 ( nr1 ) gene , making a so - called floxed ( flanked by loxp sites ) nr1 gene .
expression and function of the nr1 gene , which encodes an essential subunit required for all nmda receptors , was unaffected by these targeted insertions .
the second transgenic mouse expressed cre recombinase as a transgene under the camkii promoter . in a number of independent mouse lines they found that functional cre was only expressed in the ca1 pyramidal neurons . by interbreeding these two genetically engineered mice ,
the nr1 gene was knocked out specifically in the ca1 neurons , by the activity of cre upon the loxp sites , and thus nmda receptors were also eliminated .
however , it critically relies upon expressing cre under control of cell - type specific promoters .
although a number of promoters have been identified and shown to drive cre in stereotypical and defined patterns , it seems unlikely that this will be sufficient to target specific cortical columns in the mammalian brain .
for example , the current most specific knockout of nmda receptors in the neocortex removes the nr1 gene from the entire neocortex during development ( iwasato et al . , 2000 ) .
gene transduction using viral vectors forms a promising strategy for localized genetic manipulation of the neocortex .
non - replicative lentiviral vectors ( deglon et al . , 2000 ; naldini et al . , 1996 ) have been shown to offer long - term stable gene expression in the neocortex ( aronoff and petersen , 2006 , 2007 ; dittgen et al . , 2004 ;
lentivirus can be directly injected into mouse barrel cortex using very fine glass micropipettes ( figure 2a ) , and the injection process itself causes little damage .
the viral particles do not diffuse far from the injection site , and typically we find a local transduction of neurons within a diameter of 200 m .
transgene expression can be directly visualized by including the coding sequence for green fluorescent protein ( gfp ) in the transfer vector ( figure 2b ) .
pseudotyping with vesicular stomatitis viral glycoprotein allows entry into neurons by vector particles , but neurons remote from the injection site are not transduced .
injection of lentivector into layer 2/3 can result in transgene expression specifically within layer 2/3 ( figure 2b , left ) .
lentivectors therefore provide convenient tools for layer - specific genetic manipulation in the mouse barrel cortex .
( a ) lentivirus can be injected directly into the mouse barrel cortex using very fine glass micropipettes .
( b ) lentivector injections result in highly localized gene transduction , limited to 200 m around the injection site .
injection of gfp - expressing lentivector into layer 2/3 , therefore results in highly specific gfp expression in layer 2/3 and not elsewhere ( left ) .
gfp expression in pyramidal neurons is driven by the camkii promoter ( right ) . modified and reproduced with permission from aronoff and petersen ( 2007 ) .
first order cell - type specificity can be encoded through the promoter driving transgene expression in the lentivector . in the neocortex
, camkii is specifically expressed in the excitatory glutamatergic neurons . using a 1.3-kb fragment of the camkii promoter in lentivectors results in selective transgene expression in pyramidal neurons ( figure 2b ,
right ) ( aronoff and petersen , 2007 ; dittgen et al . , 2004 ) , with only a very small fraction of expressing cells being gabaergic neurons .
in future studies , it will be of great interest to examine whether further specificity for different types of pyramidal neurons and other cell - types in the neocortex can be engineered into lentivectors using other promoters or combinatorial genetic strategies .
the lateral dimensions of the cluster of transduced neurons following a lentivector injection into the neocortex are on the order of 200 m , similar to the width of individual mouse cortical barrel columns .
it would therefore seem likely that one could target a specific single cortical column for genetic manipulation . however , the somatotopic map of the barrel cortex is not directly visible in the living animal .
intrinsic optical imaging can be carried out through the intact skull of mice , revealing the functional location of the representation of a single whisker . in our experiments , we typically focus on the c2 whisker and its associated c2 barrel column ( figure 3a ) .
expression of cre can be functionally tested by injecting into mice carrying a lacz reporter gene , which is conditionally expressed following cre - mediated excision of a floxed stop cassette ( soriano , 1999 ) .
injecting cre - expressing lentivector into the c2 column of such a reporter mouse after mapping by intrinsic optical imaging results in labelling predominantly of the c2 barrel column ( figure 3b ) .
targeted injection of lentivector expressing gfp and cre can therefore be applied to make layer , cell - type and column specific genetic manipulations .
( a ) intrinsic optical imaging through the intact mouse skull can be used to non - invasively map the neocortex .
deflection of the c2 whisker evokes a localized hemodynamic signal highlighted by a green dot .
the functional mapping can be related to the blood vessel layout allowing targeted craniotomy and lentivector injection .
( b ) injection of lentivector was targeted to the c2 barrel column through intrinsic optical imaging .
the lentivector expressed cre recombinase and was injected into a rosa26r cre - reporter mouse , which expresses lacz in the presence of cre - activity .
in order to fully exploit the barrel cortex as a model system for active sensory processing , we need to be able to make precise manipulations in neurons of a defined barrel column .
recent advances in genetic manipulations of mice provide increasing levels of sophistication in spatiotemporal regulation of gene expression in specific cells localized to defined regions of the brain .
the genetic identification of molecular pathways underlying different aspects of cortical functional organization is also likely to lead to new therapeutic targets .
since the first genetic studies of the barrelless mutation ( welker et al . , 1996 ) , many further genes have been identified as critical for barrel cortex formation . however , genetic lesions often affect many brain areas since the gene products are widely expressed and may also alter brain development . under such conditions , it is difficult to attribute specific functions to individual genes .
the development of systems for spatiotemporally controlled knockout of genes has therefore been crucial in the field of molecular neurobiology .
the first breakthrough , developed by the tonegawa laboratory , came with the application of the cre loxp system to the brain . in their landmark papers , tsien et al .
( 1996a , b ) described a method to specifically remove nmda receptors from the ca1 region of the hippocampus , while leaving nmda receptors functional in all other brain regions .
one mouse line was generated by gene targeting strategies to insert loxp sites surrounding the second half of the nmda receptor 1 ( nr1 ) gene , making a so - called floxed ( flanked by loxp sites ) nr1 gene .
expression and function of the nr1 gene , which encodes an essential subunit required for all nmda receptors , was unaffected by these targeted insertions .
the second transgenic mouse expressed cre recombinase as a transgene under the camkii promoter . in a number of independent mouse lines they found that functional cre was only expressed in the ca1 pyramidal neurons . by interbreeding these two genetically engineered mice ,
the nr1 gene was knocked out specifically in the ca1 neurons , by the activity of cre upon the loxp sites , and thus nmda receptors were also eliminated .
however , it critically relies upon expressing cre under control of cell - type specific promoters .
although a number of promoters have been identified and shown to drive cre in stereotypical and defined patterns , it seems unlikely that this will be sufficient to target specific cortical columns in the mammalian brain .
for example , the current most specific knockout of nmda receptors in the neocortex removes the nr1 gene from the entire neocortex during development ( iwasato et al . , 2000 ) .
gene transduction using viral vectors forms a promising strategy for localized genetic manipulation of the neocortex .
have been shown to offer long - term stable gene expression in the neocortex ( aronoff and petersen , 2006 , 2007 ; dittgen et al . , 2004 ; komai et al . ,
lentivirus can be directly injected into mouse barrel cortex using very fine glass micropipettes ( figure 2a ) , and the injection process itself causes little damage .
the viral particles do not diffuse far from the injection site , and typically we find a local transduction of neurons within a diameter of 200 m .
transgene expression can be directly visualized by including the coding sequence for green fluorescent protein ( gfp ) in the transfer vector ( figure 2b ) .
pseudotyping with vesicular stomatitis viral glycoprotein allows entry into neurons by vector particles , but neurons remote from the injection site are not transduced .
injection of lentivector into layer 2/3 can result in transgene expression specifically within layer 2/3 ( figure 2b , left ) .
lentivectors therefore provide convenient tools for layer - specific genetic manipulation in the mouse barrel cortex .
( a ) lentivirus can be injected directly into the mouse barrel cortex using very fine glass micropipettes .
( b ) lentivector injections result in highly localized gene transduction , limited to 200 m around the injection site .
injection of gfp - expressing lentivector into layer 2/3 , therefore results in highly specific gfp expression in layer 2/3 and not elsewhere ( left ) .
first order cell - type specificity can be encoded through the promoter driving transgene expression in the lentivector . in the neocortex
, camkii is specifically expressed in the excitatory glutamatergic neurons . using a 1.3-kb fragment of the camkii promoter in lentivectors results in selective transgene expression in pyramidal neurons ( figure 2b ,
right ) ( aronoff and petersen , 2007 ; dittgen et al . , 2004 ) , with only a very small fraction of expressing cells being gabaergic neurons . in future studies
, it will be of great interest to examine whether further specificity for different types of pyramidal neurons and other cell - types in the neocortex can be engineered into lentivectors using other promoters or combinatorial genetic strategies .
the lateral dimensions of the cluster of transduced neurons following a lentivector injection into the neocortex are on the order of 200 m , similar to the width of individual mouse cortical barrel columns .
it would therefore seem likely that one could target a specific single cortical column for genetic manipulation .
however , the somatotopic map of the barrel cortex is not directly visible in the living animal .
intrinsic optical imaging can be carried out through the intact skull of mice , revealing the functional location of the representation of a single whisker . in our experiments , we typically focus on the c2 whisker and its associated c2 barrel column ( figure 3a ) .
expression of cre can be functionally tested by injecting into mice carrying a lacz reporter gene , which is conditionally expressed following cre - mediated excision of a floxed stop cassette ( soriano , 1999 ) .
injecting cre - expressing lentivector into the c2 column of such a reporter mouse after mapping by intrinsic optical imaging results in labelling predominantly of the c2 barrel column ( figure 3b ) .
targeted injection of lentivector expressing gfp and cre can therefore be applied to make layer , cell - type and column specific genetic manipulations .
column specific genetic manipulation of the barrel cortex . ( a ) intrinsic optical imaging through the intact mouse skull can be used to non - invasively map the neocortex .
deflection of the c2 whisker evokes a localized hemodynamic signal highlighted by a green dot .
the functional mapping can be related to the blood vessel layout allowing targeted craniotomy and lentivector injection .
( b ) injection of lentivector was targeted to the c2 barrel column through intrinsic optical imaging .
the lentivector expressed cre recombinase and was injected into a rosa26r cre - reporter mouse , which expresses lacz in the presence of cre - activity .
the highly specific expression of gfp mediated by lentivectors in itself has proven useful in analysing axonal output patterns from a given layer and column of the barrel cortex .
2007 ) used lentivirus to study the effects of sensory deprivation by whisker trimming upon excitatory axonal arbors within barrel cortex .
layer 2/3 pyramidal neurons located in spared cortex bordering upon deprived cortex were found to project axons asymmetrically , favouring the neighbouring region of spared cortex .
long - range axonal projections from the barrel cortex have also been studied and provided evidence for a prominent innervation of whisker motor cortex ( ferezou et al . , 2007 )
such a sensorimotor loop from barrel cortex to motor cortex could be intimately involved in active sensory perception .
lentivector - labelled axons from cells with soma in the c2 barrel column course through the lower layers of the neocortex ( figure 4a ) and give rise to a columnar innervation of motor cortex which spreads laterally in layer 1 ( figure 4b ) . in turn
, lentivector injections in whisker motor cortex have shown that pyramidal neurons project directly onto motor neurons of the facial nucleus , as well as into the brainstem reticular formation ( grinevich et al . , 2005 ) . these anatomical tracing studies complement results from older methods lacking genetic specificity in which it can be difficult to separate retrograde and anterograde labelling .
( a ) targeted injection of gfp expressing lentivectors into the mouse c2 barrel column , allows the analysis of the long - range axonal output .
( b ) gfp labelled axons originating from pyramidal neurons in the c2 barrel column are shown in a coronal section of motor cortex ( 1.4 mm anterior of bregma ) .
panel b ( right ) is modified and reproduced with permission from paxinos and franklin ( 2001 ) the mouse brain in stereotaxic coordinates .
although lentivectors can be used to direct transgene expression in layer , column and cell - type specific manner , they can not be used directly to knockout a target gene .
the lentivirus is a retrovirus , so its rna is reverse transcribed in infected cells and subsequently the dna is integrated into an unspecified location of the host genome . in order to knockout a specific gene ,
it is therefore necessary to use a two component system . in our study , we combined lentivector expressing cre with gene - targeted mice carrying a floxed nmda receptor 1 gene ( aronoff and petersen , 2007 ) .
transduced cells were visualized through co - expression of gfp from the same lentivector ( figure 5a ) . using this manipulation ,
the floxed nr1 gene could be deleted in a layer , column and cell - type specific manner , since the genetic knockout only occurs in gfp / cre - expressing neurons .
electrophysiological analysis of floxed nr1 mice revealed that long - lasting nmda receptor - dependent currents at positive potentials were strongly reduced or absent in cells expressing gfp and cre ( figure 5c ) .
nmda - receptor dependent long - term potentiation was also found to be reduced in these cre - expressing neurons of floxed nr1 mice ( aronoff and petersen , 2007 ) .
such layer- and cell - type- specific knockout of nmda receptors may help shed further light on their involvement in experience - dependent plasticity ( bender et al .
, 2006 ; clem et al . , 2008 ) and the roles of presynaptic nmda receptors ( brasier and feldman , 2008 ) . in future studies , it will be interesting to directly compare this cre
loxp knockout approach with knockdown approaches based on sirna ( mello and conte , 2004 ) .
( a ) imaging by two - photon microscopy of lentivector transduced pyramidal neurons expressing gfp and cre recombinase in a floxed nr1 mouse .
the dodt contrast image ( upper left ) , shows the whole - cell recording electrode filled with alex 594 ( upper right ) targeted to a gfp expressing neuron ( lower left , overlay lower right ) .
( b ) whole - cell recording of a control layer 2/3 pyramidal neuron near the lentivector injection site .
the neuron did not express gfp and had normal nmda receptor dependent currents evoked by an extracellular stimulus in layer 4 and measured at + 40 mv .
( c ) whole - cell recording of a layer 2/3 pyramidal neuron expressing gfp and cre recombinase in a floxed nr1 mouse .
synaptically evoked currents lack the long - lasting nmda - receptor dependent component at + 40 mv , indicating a functional knockout of nr1 . modified and reproduced with permission from aronoff and petersen ( 2007 ) .
the nmda receptor provided an attractive first candidate for this analysis , since it is thought to play a pivotal role in learning and memory .
the specific knockout of nmda receptors in a single column and layer of the mouse somatosensory cortex might be of particular interest to combine with behaviours mediated by a single whisker . using these strategies one could ask highly specific questions relating to the functional contributions of individual genes to specific behaviours . for example , one might examine whether the knockout of nmda receptors in layer 2/3 of the c2 barrel column would affect learning of the gap - crossing task with the single c2 whisker .
there are increasing numbers of genes that have been floxed , and their functional roles in the mouse barrel cortex could be investigated with similar approaches . in the mouse barrel cortex
such highly specific genetic manipulations can not only be correlated with learned behaviours , but also be investigated in terms of specific changes to well - defined synaptic circuits .
the anatomical map of the barrels allow simple alignment and comparison of data obtained from different animals .
both imaging and electrophysiological methods have been applied to study the functional activity of the somatosensory cortex of awake behaving mice ( crochet and petersen , 2006 ; dombeck et al . , 2007 ;
in addition to correlating neuronal activity with anatomical structure and behaviour , it is critical to obtain causal evidence for the involvement of specific neurons and to investigate the underlying mechanisms . local genetic manipulations offered by viral gene transduction provide a simple route to first order layer , column and cell - type specificity .
genetically manipulated cells expressing gfp can be visualized at high resolution in vivo using two - photon microscopy ( dittgen et al . , 2004 ; stettler et al . , 2006 ) , but this is usually limited to the superficial cortical layers .
advances in endoscopic imaging technology may enable application of these methods for studying deep brain areas ( flusberg et al . , 2005 ) , but inevitably this will result in some damage to the brain upon the insertion of optical fibres .
in this review we have focused exclusively on the application of lentivector to mouse neocortex , but other viruses , such as adeno - associated virus , have been shown to provide equally stable vectors for gene delivery ( recently reviewed aronoff and petersen , 2006 ; luo et al . , 2008 ) .
lentivirus and adeno - associated virus have broadly similar characteristics in the context of expressing transgenes in the mammalian brain .
lentivirus can support slightly larger transgenes than adeno - associated virus , which has a smaller physical size and therefore also diffuses further from the injection site . because the adeno - associated virus does not prominently integrate into the host cell genome
, it therefore has the advantage of not disrupting native gene expression patterns , which might occur from a lentivector integration site .
importantly , both lentivirus and adeno - associated virus have been shown to work well in many brain areas of both rodents and primates ( aronoff and petersen , 2006 ; luo et al . , 2008 ; naldini et al . , 1996 ;
; xiao et al . , 1999 ) , and indeed using viral vectors provides an important translational research direction towards gene therapy .
future developments in vector technology using combinatorial genetic methods will likely further increase the cell - type specificity ( wickersham et al .
, 2007a , b ) . through iterative cycles of computational modelling , neurophysiology and genetic manipulation in mouse barrel cortex
, it seems likely that we will ultimately gain a deep insight into basic cortical functions underlying sensory perception and associative learning .
the authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest .
Output:
| sensory information is processed in distributed neuronal networks connected by intricate synaptic circuits .
studies of the rodent brain can provide insight into synaptic mechanisms of sensory perception and associative learning .
in particular , the mouse whisker sensorimotor system has recently begun to be investigated through combinations of imaging and electrophysiology , providing data correlating neural activity with behaviour . in order to go beyond such correlative studies and to pinpoint the contributions of individual genes to brain function , it is critical to make highly controlled and specific manipulations . here , we review recent progress towards genetic manipulation of targeted genes in specific neuronal cell types located in a selected cortical layer of a well - defined cortical column of mouse barrel cortex
. the unprecedented precision of such genetic manipulation within highly specific neural circuits may contribute significantly to progress in understanding the molecular and synaptic determinants of simple forms of sensory perception and associative learning . |
PubmedSumm118603 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: individual energy expenditure may differ up to 20-fold between resting conditions and high physical activity , but such differences have until now been weakly correlated to energy intake at subsequent meals .
frequent episodes of positive energy balance can lead to insulin resistance , overweight , obesity , diabetes , and heart disease [ 1 , 2 ] .
dietary regimes that attempt to restrain eating have been only marginally successful [ 3 , 4 ] and the feasibility of self - regulation of energy intake regimes has been questioned .
a key reason for this lack of success may be that most dietary methods rely on weekly or monthly measurements of weight .
these measurements provide no immediate feedback to dieters , who usually ingest food at least three times daily .
blood glucose concentration ( bg ) is a reliable index of energy availability to body cells [ 68 ] .
it seems reasonable to assume that bg slowly declines in the absence of food intake during the day until hunger emerges to trigger eating behaviour [ 9 , 10 ] .
previous studies suggested that waiting for hunger before eating is associated with a significant decrease in energy intake [ 1115 ] .
subjects can be trained to predict when bg is low by attending to their subjective experience of hunger .
thus low blood glucose ( lbg ) can be regarded as a biochemical marker for hunger .
the first intimations of hunger we term initial hunger ( ih ) , to differentiate it from the uncomfortable symptoms that occur when hunger is prolonged .
ih is not a reflex conditioned by external events such as time or social circumstances .
for example , ih is not conditioned by meal times since it arises unexpectedly ( outside meal times ) if energy content of the previous meal was not planned to cover the intermeal interval .
the initial hunger meal pattern ( ihmp ) is a pattern of eating such that ih is present before most meals .
we reasoned that the ihmp should predict closely regulated bg concentration with associated improvements in metabolic biomarkers . in this study , we tested the hypothesis that the ihmp is associated with improvements in metabolic biomarkers , in particular insulin sensitivity .
the paediatric gastroenterology unit of florence university recruited 143 subjects to this study from 1996 to 2000 . this unit diagnoses and treats celiac disease in children and adults .
aged 18 to 60 years , subjects suffered from symptoms of functional bowel disorders such as dyspepsia , abdominal pain , and diarrhoea ( figure 1 ) [ 18 , 19 ] .
they showed no morphological , physical , or biochemical signs of organic disease [ 11 , 18 , 19 ] .
subjects with impaired glucose tolerance ( fasting plasma - glucose > 115 mg / dl ( 6.4 mmol / l ) ) , and noninsulin dependent diabetes mellitus ( niddm ) , celiac , liver , heart , brain , thyroid , and kidney diseases were excluded from this study ( figure 1 ) . written informed consent was obtained from all subjects .
the trained group continued their regular work or recreational activities under tutorial assistance for seven weeks and maintained the ihmp for a further three months independently ( figure 1 ) .
subjects were trained in the ihmp , first by identifying ih , which was guided by consistency in subjective sensations and the association of these sensations with bg measurement . during training ,
subjects measured capillary blood by portable glucometer ( glucocard memory ; menarini diagnostics ; florence , italy ) in the 15 min before a meal .
seven - day home diaries reported bg measurements and presence or absence of ih before the three main meal times . also recorded in the diary were energy and vegetable intake , hours in bed , and hours spent during physical and outdoor activities ( weekly mean and sd ) .
subjects were advised that bg measurements after taking small quantities of food ( even a few grams ) , after changes in ambient temperature , after physical activity such as walking or cycling , and when under psychological stress would be misleading since we had previously found that bg and ih do not correlate well under these conditions .
subjects reported ih as gastric pangs , sensations of emptiness and hollowness , and mental or physical weakness .
ih was cultivated pre - meal by adjusting composition , portion size , or timing of food intake .
after a few days of trial and error , and sometimes irregular meal times , subjects were able to arrange their food intake so that ih appeared before the usual three meal times per day with an average error of half - an - hour in 80% of instances [ 15 , 16 , 2023 ] .
training ended after the first 7 weeks , to be resumed only at the end of the investigation .
thus , after the first 7 weeks , subjects relied upon the identified subjective sensation ( ih ) alone , as the signal to begin a meal .
control subjects ( n = 31 ) were given the same information on food energy content and were recommended vegetable intake and physical activity per day as were the trained subjects ( weeks 07 , figure 1 ) .
120 subjects who completed the study were assessed for blood parameters at baseline ( before training ) , after the first 7 weeks of training , and at the end of the investigation after a further three months ( total duration of the investigation : 5 months ) . during the glucose tolerance test , after a 12-hour overnight fast , all subjects were given a 75 g - oral glucose load .
venous blood samples were taken immediately before glucose was administered , and 30 , 60 , 90 , 120 , and 180 min thereafter to determine plasma glucose and serum insulin .
usa ) . from the glucose tolerance test ( gtt ) , we calculated the area under the curve ( auc ) , the index of whole - body insulin sensitivity ( 10,000/square root of [ fasting glucose fasting insulin ] [ mean glucose mean insulin during gtt ] ) , and the insulinogenic index of beta cell function ( ratio of the increment of plasma insulin to that of plasma glucose 30 min after glucose loading ) .
the primary endpoint was the change in insulin sensitivity from baseline at 5 months in trained subjects compared to controls .
analyses were also performed on beta cell function , bg auc , gtt measurements of bg and insulin concentrations , and mean pre - meal bg and hba1c values as well as energy intake , bmi , body weight and arm and leg skinfold thickness .
previous work in similar patients found that the insulin sensitivity index in the intervention group was greater by 3 than that in the control group , with a standard deviation ( sd ) of 3.0 .
based on these figures , our sample size calculations suggested that we needed a minimum of 14 subjects in each comparison group to detect a similar difference in group means , with a power of 80% and a 1 sided alpha of 0.05 . a list was divided into blocks of 1 to 4 places , and the blocks were randomly assigned using armitage even and odds random numbers on a 3 : 1 ratio to either training or control groups .
a dietician kept the list and subsequently assigned each recruited subject to the first empty list place .
values are expressed as means sd , except in figure 2 , where the standard error is shown .
logistic regression analysis was used to investigate the association of training with bg mean , hb1c , insulin and bg aucs , intakes and anthropometric measures ( trained versus untrained control groups ) for significance of multiple results .
the significance of difference and correlation was set at p < .05 in these analyses .
yates test and two - tailed student 's t - test on paired or unpaired samples according to data requirements were used to analyse the significance of difference and two - tailed student 's t - test for correlation .
the significance was set at p < .05 for single measurements and at p < .025 for the gtt insulin and bg aucs .
, cary , nc , usa ) were used for data presentation and for statistical analyses . a training effect and correlations between the two body size parameters ( weight and bmi ) , the two energy - balance parameters ( arm and skinfold thickness ) ,
the four metabolic indexes ( mean bg and hba1c values , and bg and insulin aucs ) , and three intake factors ( energy , fruit , and vegetable ) were longitudinally investigated ( i.e. , on post minus predifferences ) by simple , linear correlation and regression analyses in all of the 120 subjects completing the study ( figure 1 ) .
figure 1 shows the flow chart of participants through each phase of the study .
data were eventually collected from 120 subjects who completed the study ( 60 females and 60 males , 89 trained subjects and 31 control subjects ) . in this study the protocol was to follow the ihmp .
we do not have data on the extent to which ih was present pre - meal for each meal , that is , we do not know how closely each subject adhered to the ihmp . achieving the ihmp appeared to be difficult for 12 subjects who had high pretraining mean bg concentrations ( e.g. , around 100 mg / dl ) or participated in heavy manual labour , especially in cold conditions .
although some subjects may not have been faithful to the ihmp for all meals , we have included all those who completed the study in the final analysis , since it was our intention to treat them [ 30 , 31 ] .
twenty - three subjects ( 18 trained and 5 control ) did not complete the study ( dropouts ) . all were contacted by telephone .
their given reasons were that they required no further training or had busy schedules .
to ascertain whether these biases could have affected the generalisability of the study 's conclusions , we performed a sensitivity analysis using baseline and 7-week data from all 23 dropouts .
the 18 trained dropouts significantly decreased mean bg ( from 83.3 5.9 mg / dl to 78.9 5.4 mg / dl ; p = .005 ) , energy intake ( from 1651 451 to 1124 401 ; p = .0001 ) , bmi ( from 23.7 3.4 to 22.9 3.2 ; p = .04 ) , and arm skinfold thickness ( from 20.5 8.5 to 18.5 8.8 ; p = .03 ) .
the 5 control dropout subjects showed no change in these assessments . since no significant gender difference in baseline mean
bg concentrations was observed in the control group ( females : 82.3 8.0 mg / dl ; n = 14 ; and males : 87.5 7.6 mg / dl ; n = 17 ; student 's t - test for unpaired data : p = .075 ) and in the training group ( females : 84.3 8.7 mg / dl ; n = 46 ; and males : 87.5 10.6 mg / dl ; n = 43 ; p = .115 ) , the measurements from both genders were pooled in each group ( figure 1 ) .
baseline bg means of the control subjects ( 85.2 8.1 mg / dl ; n = 31 ) did not differ from those of the training subjects ( 85.9 9.7 mg / dl ;
baseline values of mean age , school education years , body weight , bmi , arm and leg skinfold thickness , and blood values did not significantly differ between control and trained groups ( tables 1 and 2 ) .
significant decreases among trained subjects compared to controls were found in insulin sensitivity index , insulin and bg peaks , insulin at 60 minutes and 90 minutes during gtt , glycated haemoglobin , mean pre - meal bg , bg diary standard deviation ( sd ) , energy intake , bmi , body weight , arm and leg skinfold thickness .
index of beta cell function changed from 1.0 0.8 to 1.1 1.1 in trained subjects and from 1.0 1.0 to 0.7 0.6 in control subjects .
insulin and bg aucs in the trained group significantly decreased in the pre / postcomparison but the decreases were not significantly different from those of the control subjects .
a significant decrease of preprandial bg mean values achieved during training was maintained three months after the training period ceased ( baseline : 85.6 9.5 mg / dl ; after 5 months : 79.4 6.5 mg / dl ; n = 89 ; student 's t - test for paired data : p < .0001 ) ( table 2 ) .
in contrast , mean preprandial bg in control subjects did not change from baseline ( baseline : 85.2 8.1 mg / dl ; after 5 months : 85.3 7.6 mg / dl ; n = 31 ; p = .935 ) and the longitudinal difference from the trained group was significant ( p < .001 ; table 2 ) . the absolute pre
/ post change ( increase or decrease ) in 31 control subjects was 6.0 4.6 mg / dl ( 13.2% 10.1% of the baseline range in mean bg in the 120 investigated subjects : 64.5 mg / dl to 109.9 mg / dl ) .
factors that most characterized the differences between the trained group and the control group were investigated in all 120 subjects together by a logistic regression analysis .
energy intake ( p = .004 ) and hba1c ( p = .0001 ) were significantly and negatively associated with the training .
the training was significantly and negatively associated with bmi ( p = .001 ) and with arm and leg skinfold thickness ( balance during the 5 months of investigation ; p = .005 and p = .015 , resp . ) .
decrease in bmi by training was significantly associated with decreases in energy intake ( p = .001 ) and insulin auc ( p = .001 ) .
trained subjects reported few negative effects when adjusting their food intake and in accommodating irregular intermeal intervals in the first few days of trial and error .
the reported adverse effects included a slightly depressed bg ( below 60 mg / dl ( 3.3 mmol / l ) ) and weakness or abdominal pain .
however , from our sensitivity analysis , we conclude that the dropout subjects are unlikely to represent a significantly different population with respect to the endpoint measures of this study and that the absence of final data from these subjects is unlikely to have significantly affected the overall results .
further investigation will be necessary to evaluate the effect of the ihmp in other populations and what reminder training might be necessary to ensure compliance with the ihmp over years .
a seven - week training program to establish the ihmp led to significant decreases in insulin sensitivity index , insulin and bg peaks , glycated haemoglobin , mean pre - meal bg and bg diary sd .
ih may represent an important afferent arm of a physiological regulation mechanism that provides meal - by - meal feedback on energy need thus optimizing energy intake .
the observed improved insulin sensitivity may reflect lowered energy intake resulting from the ihmp . before training
, mean pre - meal bg showed high intersubject variability , in agreement with other authors ' findings .
this variability has engendered a perception that bg has no relevance to food intake regulation .
the mean pre - meal bg in trained subjects decreased significantly over 5 months , whereas control subjects showed no change .
we suggest , therefore , that inter - subject variability arises because in many subjects hunger ( and thus lbg ) is , by habit , forestalled by premature food intake leading to sustained mild hyperglycemia . that the absolute pre / post change ( increase or decrease ) in pre - meal bg was modest in 31 control subjects ( 13.2% 10.1% of baseline range in mean bg variation of 120 investigated subjects ) supports the contention that in untrained subjects eating occurs according to long - standing habit .
we suggest the ihmp offers a viable alternative to low fat and low carbohydrate diets that is safe , cost - effective , and likely to be met with greater acceptance since it does not involve energy deprivation .
for example , the chronic subclinical inflammation indicated by c reactive protein ( crp ) is now seen as part of the insulin resistance syndrome [ 33 , 35 ] .
trained subjects showed a cumulative energy balance that was negative after 5 months , and the longitudinal difference was significant in comparison with control subjects .
elsewhere , we describe the effect of the ihmp on body weight in relation to baseline weight and mean bg , using a larger sample size .
our data suggest that ( i ) ih provides meal - by - meal feedback allowing the conscious formation of a new eating pattern ( ihmp ) and sustained self - regulation of energy intake , and ( ii ) over a five - month period the ihmp is associated with improvement in insulin sensitivity , lbg , hba1c , and other cardiovascular risk factors .
these findings , together with those of an associated study on weight , suggest that the current epidemic of insulin resistance and overweight may have its origin in noncognizance of hunger .
this may owe to habitual forestalling of hunger in early life and subsequent reinforcement of this behaviour pattern . by restoring and validating hunger ,
the ihmp could help in the prevention and treatment of diabetes and obesity and associated disorders .
Output:
| background .
excessive energy intake has been implicated in diabetes , hypertension , coronary artery disease , and obesity .
dietary restraint has been unsuccessful as a method for the self - regulation of eating .
recognition of initial hunger ( ih ) is easily learned , can be validated by associated blood glucose ( bg ) concentration , and may improve insulin sensitivity . objective . to investigate whether the initial hunger meal pattern ( ihmp ) is associated with improved insulin sensitivity over a 5-month period .
methods .
subjects were trained to recognize and validate sensations of ih , then adjust food intake so that initial hunger was present pre - meal at each meal time ( ihmp ) .
the purpose was to provide meal - by - meal subjective feedback for self - regulation of food intake . in a randomised trial
, we measured blood glucose and calculated insulin sensitivity in 89 trained adults and 31 not - trained controls , before training in the ihmp and 5 months after training .
results . in trained subjects ,
significant decreases were found in insulin sensitivity index , insulin and bg peaks , glycated haemoglobin , mean pre - meal bg , standard deviation of diary bg ( bg as recorded by subjects ' 7-day diary ) , energy intake , bmi , and body weight when compared to control subjects . conclusion .
the ihmp improved insulin sensitivity and other cardiovascular risk factors over a 5-month period . |
PubmedSumm118604 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: fundamental questions in peptide biology are the extent to which any given peptide operates in isolation versus interdependently , locally or systemically , and via a single pleiotropic or multiple distinct receptors .
investigations subsequently unveiled multiorgan expression [ 24 ] , multivariate actions , and complex modulation of and by collateral effectors [ 1 , 4 ] : table 1 .
the burgeoning repertoire of ghrelin actions mimics that of inhibin and activin [ 6 , 7 ] , which were originally isolated as regulators of follicle - stimulating hormone secretion , and thereafter recognized for hematopoietic and oncologic activity .
analogously , prominent clinical applications of ghrelin / ghs may involve not only gh - stimulating effects but also appetitive , metabolic , cardiovascular , locomotive , and gastrointestinal signaling : figure 1 .
recent development of transgenic mice expressing ghrelin - egfp ( enhanced green fluorescent protein ) should permit more detailed mapping of ghrelin - expressing neurons in hypothalamic arcuate and ventromedial nuclei [ 810 ] and ghrelin - expressing cells in gastric oxyntic glands , pancreatic islets ( epsilon cells ) , the anterior pituitary gland , bone marrow , and other less well - studied sites [ 4 , 11 , 12 ] .
the etymology of ghrelin is ghre for growth , consonant with the report by bowers et al . of direct pituitary
the peptides were initially termed gh - releasing peptides ( ghrps ) , and more recently gh secretagogues ( ghss ) to include congeneric molecules .
multiple peptidyl and several nonpeptidyl analogs of ghrelin ( ghs ) have been developed and assessed functionally over the last three decades .
the ghrelin receptor was cloned in 1996 by howard et al . based upon phospholipase c - mediated intracellular inositol
triphosphatate - dependent ca signal generation in transfected cells . in certain systems , such as pituitary somatotropes , gastric oxyntic cells , appetitive neurons , pancreatic islets , and endothelial cells , additional messengers like phosphoinositidyl-3-kinase , akt / protein kinase b , adenosine monophosphate protein kinase ( amp kinase ) , and nitric oxide may modulate ghrelin 's actions [ 1320 ] : table 1 .
mitogen - activated protein kinases ( mapks ) and extracellularly regulated kinases ( erks 1/2 ) may mediate certain of ghrelin 's proliferative and antiapoptic effects [ 15 , 21 , 22 ] .
ghrelin and cognate receptor , ghs - r1a , are distinct entirely from gh - releasing hormone , ghrh , and its receptor isolated in 1982 by the guillemain and vale laboratories from human pancreatic neoplasms [ 23 , 24 ] .
the homotypic ghrh receptor is an adenylyl cyclase - activating seven transmembrane - spanning gtp - binding protein .
ghrh neurons in the arcuate nucleus express ghs - r1a , but hypothalamic ghrelin neurons do not manifest ghrh receptors .
both neuronal ensembles are extensive and project to the external layer of the pituitary stalk .
nonetheless , to date , any direct role for hypothalamic release of ghrelin to the pituitary gland remains undocumented .
ghrelin is unusual in that existence of the receptor was predicted three decades and cloned three years , before the natural ligand was identified by kojima et al . in 1999 .
mutational disruption of constitutive ghs - r1a activity is associated with short stature in humans , whereas overexpression of ghs - r1a on ghrh neurons augments postweaning growth , reduces fat mass , and augments ghrh and gh gene expression in mice .
thus , ghs - r1a is an amplifier of ghrh outflow as well as a direct effector of pituitary gh secretion .
exogenous ghs partially overcomes gh inhibition by glucose and infused somatostatin [ 29 , 30 ] .
neurophysiological data and immediate - early gene responses have revealed two additional mechanisms of ghrelin action , namely , partial antagonism of noncompetitive hypothalamic and pituitary inhibition by somatostatin and of hypothalamic melanocortin and leptin pathways [ 3140 ] .
figure 2 depicts a model , which incorporates several major actions of ghrelin / ghs within the gh axis .
this model does not include pituitary ghrelin , which is downregulated by excessive thyroxine , glucocorticoid , or brain - gh feedback and upregulated by ghrh .
selective silencing of the pituitary ghrelin gene will be required to discern its physiological role .
ghrelin is unique as the first acylated peptide recognized in mammals requiring a short - chain fatty - acid ( octanoyl , decanoyl , or decenoyl ) moiety linked to the third n - terminal amino acid ( usually serine ) for primary biological activity , namely .
ghrh and gh release , locomotor suppression and appetite stimulation [ 26 , 4345 ] .
decanoyl and octanoyl moieties seem equipotent . the enzyme mediating ser acylation was cloned by the brown and goldstein laboratory in 2008 and named ghrelin octanoyl - acyltransferase ( goat ) [ 4648 ] .
it is expressed in pancreas , stomach , skeletal muscle , heart , intestine , bone , and other organs and is endproduct inhibited and fatty - acyl substrate and fasting induced [ 5052 ] .
goat protein and transcripts exist in individual ghrelin - containing gastric mucosal oxyntic cells .
regulation may exist pretranslationally also , since natural antisense ghrelin rna 's can be demonstrated by analysis of human genomic dna [ 54 , 55 ] .
a second acyltransferase , termed microsomal zinc - stimulated serine ( ser ghrelin ) octanoyltransferase , distinct from goat , was cloned by ozawa et al . in 2009 .
its in vivo role is not yet known but might include negative regulation of goat via the octanoylated products generated .
unacylated ghrelin competes with acylghrelin for ghs - r1a to a negligible degree , namely , with a kd of 13 m , which is four orders of magnitude greater than that for bioactive peptide .
deacylases ( esterases ) of ghrelin exist in the blood and stomach , which may be nonselective [ 58 , 59 ] .
goat can utilize both ghrelin ( 14 ) and ghrelin ( 15 ) as substrates for serine acylation , consistent with their core structure [ 46 , 60 ] .
des - gln acylghrelin ( 127 ) , an alternative transcript lacking glutamine in n - terminal position 14 , is also fully active on the ghs - r1a receptor . ghrelin 's amino - acid sequence is significantly conserved in fish , reptiles , amphibia , birds , and mammals .
congeneric molecules include ghrp-2 , ghrp-6 , hexarelin , ipamorelin , ibutamorelin , and the nonpeptide mk-0677 , which like ghrelin rapidly induce inositol triphosphate , diacylglycerol , and ca release via the ghs - r1a [ 51 , 6367 ] .
ghrelin concentrations in blood comprise principally desacyl - ghrelin ( 85%90% ) and in lesser amounts acylghrelin ( 10%15% ) and c - terminal proghrelin peptides [ 68 , 69 ] . in large cohorts , ghrelin is higher in women than men and declines with age , body mass index ( bmi ) , hypertension , and other markers of the metabolic syndrome .
the inverse relationships between ghrelin and both bmi and insulin concentrations appear to explain much of the age effect .
appropriate sample collection and storage are necessary to limit ghrelin deacylation before assay [ 72 , 73 ] .
although its exact role is not known , desacyl - ghrelin can exert a variety of agonistic and antagonistic actions [ 7476 ] , as discussed further in the relation to the ghrelin receptor .
octanoylated and total ghrelin levels in the stomach and blood rise between meals , during fasting , in cachexia , anorexia , or malnutrition , type i ( insulinopenic ) diabetes mellitus , after acute endotoxin exposure , overnight during initial deep sleep and in response to estradiol ( e2 ) , acute hypoglycemia , glucagon infusion , vagal stimulation , and chronic octanoate ingestion [ 7789 ] : figure 3 . in mice ,
plasma bioactive decanoylated ghrelin increases and octanoylated ghrelin paradoxically decreases during fasting , suggesting precise posttranslational control .
unlike gastric ghrelin , hypothalamic ghrelin gene transcript and peptide levels fall during short - term fasting . in various studies , serum
total ghrelin concentrations correlate positively with e2 , igfbp-1 , and creatinine concentrations , and negatively with somatostatin , insulin , thyroxine , leptin , and testosterone ( t ) concentrations and arterial blood pressure [ 70 , 82 , 86 , 9198 ] . thus , ghrelin levels rise not only in fasting individuals but also in estrogen / progestin - treated women [ 99101 ] , combined antiandrogen and progestin - treated men , and the estrogen - rich milieu of the late follicular phase of the menstrual cycle in one but not another study [ 92 , 102 ] .
conversely , ghrelin levels fall in the high - testosterone milieu of male puberty .
gastric ghrelin - secreting cells express estrogen receptor - alpha , thus potentially mediating some sex - steroid effects .
indeed , gonadal downregulation in girls and parenteral ( but not transdermal ) testosterone administration in boys diminish plasma ghrelin concentrations [ 104 , 105 ] . in addition ,
clinical investigations indicate that e2 or t supplementation can potentiate gh secretion stimulated by a fixed submaximal dose of ghs / ghrelin [ 106112 ] .
on the other hand , low - dose transdermal e2 administration did not augment maximal gh stimulation by ghrelin in postmenopausal women , and the potentiating action of t administration on ghs was not evident in the dog , rat , or older men [ 114 , 115 ] . thus , more data are needed on the developmental dependence of sex - steroidal facilitation of ghs action .
the differences before and after puberty do not seem to be due to feedback by differing gh levels , since acute infusion of gh or a gh - receptor antagonist does not feed back onto ghrelin secretion [ 116 , 117 ] .
chronic gh excess or deficiency and exercise also do not consistently modify ghrelin production in humans or animals [ 118120 ]
. food intake , especially amino acids , glucose but not fructose , dodecanoate , and other long - chain fatty acids , t administration , euglycemic hyperinsulinemia , impaired glucose tolerance , infusion of free fatty acids , somatostatin , cortistatin or urocortin , obesity ( elevated body - mass index and increased total , subcutaneous or visceral fat ) , weight gain , hyperthyroidism , and leptin injection suppress ghrelin concentrations [ 86 , 97 , 116 , 117 , 128144 ] .
a possible intracellular mediator of fasting and feeding 's reciprocal control of ghrelin secretion is the mammalian target of rapamycin , which is suppressed by fasting . in general ,
total ghrelin concentrations nearly double before meals and fall to a nadir about one hour thereafter .
protein ( more than lipid ) ingestion strongly suppresses plasma acylghrelin , whereas carbohydrate initially suppresses and then elevates circulating ghrelin in humans .
gastrectomy reduces total ghrelin concentrations by 65%80% ( to 20%35% of baseline ) , thereby verifying that the stomach is the major source of this hormone .
acylated ghrelin typically changes in parallel with total ghrelin availability and in the fed state may rise recurrently before gh pulses .
dissociations between acyl and desacyl - ghrelin levels occur after fiber versus total energy intake , intravenous glucose infusion , in renal failure , and in the portal vis - - vis hepatic veins because of preferential liver extraction of the acylated moiety . in clinical studies ,
meal - induced depression of ghrelin levels may be attenuated in children compared with adults , and in women with polycystic ovarian syndrome ( pcos ) compared with healthy women , but accentuated in african - american compared with caucasian women [ 151154 ] .
the antiandrogen , flutamide , increased ghrelin levels in patients with pcos , suggesting suppression of ghrelin production via the androgen receptor in this hyperandrogenemic syndrome .
the metabolic clearance rates of acyl and desacyl - ghrelin injected by bolus in humans differ by several - fold : figure 4(a ) .
active ghrelin ( 1 g / kg ) is removed more rapidly ( half - life 21 minutes ) than unmodified ghrelin peptide ( 36 minutes ) and partitions into a larger but finite distribution volume consistent with greater lipophilicity . at a higher ghrelin dose ( 3 g / kg ) , half - lives are 47 and 64 minutes for acylated and unacylated peptide .
this concentration - dependence suggests interconversion of ghrelin isoforms and/or 2-compartment kinetics of acylated peptide .
figure 4(b ) illustrates that steady - state bioactive - ghrelin concentrations are not saturable at metabolic clearance rates of up to 60 l / kg / day .
acylated peptide binds to plasma high - density lipoproteins containing paraoxonase ( an esterase ) , but the size and fate of this reservoir are not known .
an additional gastric ghrelin deacylation enzyme has been identified , lysophospholipase i . the exact degree to which this enzyme regulates ghrelin biosynthesis secretion is still unknown .
desacyl - ghrelin appears to undergo significant renal clearance , whereas acylghrelin is extracted substantially by the liver [ 142 , 157 ] .
the ghrelin receptor exhibits high ( about 50% ) basal constitutive activity [ 158 , 159 ] and responds to inverse agonists , partial agonists , and allosteric antagonists [ 160 , 161 ] .
in particular , inverse agonists repress basal receptor activity , as defined by inositol - triphosphate , ca , or diacylglycerol signal generation [ 159 , 162 ] .
since blood ghrelin levels rise between meals and overnight , a ghrelin - receptor inverse agonist might be used to minimize hunger at these times and overnight . in two families , short stature accompanied ghs - r1a mutations that reduced constitutive ghs - r1a activity , thereby implying biological relevance of basal receptor activity .
multiple experimental strategies have been employed to test the biological impact of silencing ghrelin or ghs - r1a activity : table 2 .
consistent outcomes in animal models comprise loss of appetitive , locomotor , and somatotropic regulation by exogenous ghrelin ; modest reduction of body weight , igf - i concentrations , and gh pulses in the female animal ; increased fat oxidation ; a rise in mean arterial blood pressure ; reduced obesity and improved glucose tolerance , but with a potentially higher risk of hypoglycemia during prolonged fasting ; and decreased development of fatty diet - induced diabetes mellitus [ 164168 , 174185 ] .
double transgenic knockout of ghrelin and cognate receptor is marked by diminished adult body weight , greater energy expenditure , and higher locomotor activity [ 169 , 186 ] .
thus , ghs - r1a is a physiological mediator of ghrelin 's stimulation of gh secretion , repression of oxygen consumption and locomotor activity , and enhancement of appetite .
ghs receptor type 1b arises from a nonspliced transcript , whose product does not bind acylghrelin or confer known bioactivity [ 5 , 187 ] . unlike ghrelin , synthetic ghs 's acting via ghs - r1a
moreover , multiple biological effects have been reported for desacyl - ghrelin , which essentially does not bind ghs - r1a .
a partial registry of effects comprises differentiation of skeletal muscle ; relaxation of vascular smooth muscle ; suppression of proinflammatory cytokines ; inhibition of apoptosis of cardiomyocytes , pancreatic beta cells , and endothelial cells ; antagonism of ghrelin 's stimulation of somatic growth , hepatic gluconeogenesis , and appetite ; hypotensive effects ; repression of fatty - acid oxidation ; and stimulation of adipogenesis [ 22 , 75 , 188201 ] : table 3 .
although local acylation could explain certain actions of unacylated ghrelin , other effects that oppose or differ from those of acylated peptide raise the possibility of non - ghs - r1a mediation .
synthetic analogs of ghrelin likewise may exhibit partial agonism ( e.g. , stimulation of appetite but not gh release , and vice versa ) , antagonism , and inverse agonism despite similar ghs - r1a binding affinities [ 160 , 202207 ] .
to date , no desacyl - ghrelin and no other ghs receptors have been cloned to explain such data .
acylghrelin , unlike the naked peptide , is a consistently effective agonist of gh secretion in multiple species from fish to mammals [ 34 , 65 , 215221 ] .
nonacylated synthetic ghs can stimulate gh secretion in occasional models [ 222224 ] . in fish , desacyl - ghrelin may function as an inhibitor of ghrelin 's stimulation of appetite and locomotion . in mice ,
transgenic overexpression of desacyl - ghrelin decreases food intake , gastric emptying , gh ( female animal ) and igf - i ( both sexes ) concentrations , body weight and length , and gh release induced by exogenous ghrelin .
cns delivery of desacyl - ghrelin in the rat likewise impedes food intake and gastric emptying [ 190 , 196 ] . in humans ,
exogenous desacyl - ghrelin does not restrict ghrelin - induced gh secretion but disinhibits ghrelin 's repression of insulin secretion [ 210 , 221 , 226 ] .
exceptions include the pituitary glands of embryonic fish and prepubertal rats in vivo and ovine somatotropes in vitro [ 227229 ] .
both gh and igf - i can feed back to inhibit hypothalamopituitary stimulation by ghrelin / ghs , but feedback inhibition is less marked on ghs than ghrh stimulation .
feedback appears to involve induction of periventricular hypothalamic somatostatin outflow , which quenches both ghrh and gh secretion .
active ghrelin acts as an amplifier of ghrh , the primary agonist of gh secretion .
human and murine hypothalami contain a wide network of ghrelin - expressing neurons , which extends across the arcuate , ventromedial , paraventricular and multiple other nuclei [ 811 , 231235 ] .
antisense rna - mediated silencing of the murine ghs-1a receptor localized to ghrh neurons resulted in reduced adult weight , fat mass , pulsatile gh secretion , and igf - i production in the adult female only .
arcuate - nucleus ghrh - gene expression also declined in these animals , indicating that ghs - r1a not only transduces ghrh release but also maintains ghrh gene transcription [ 237 , 238 ] .
consistent with this inference , ghs ' stimulation of maximal ( 5 - 35-fold ) gh release requires an intact hypothalamopituitary unit allowing ghrh outflow to the pituitary [ 239242 ] .
accordingly , ghrh ( / ) mice , ghrh - receptor ( / ) mice , and rare patients with inactivating mutations of the ghrh receptor or congenital aplasia of the pituitary stalk are hyposomatotropic , and respond sparingly ( < 3-fold ) to ghrelin / ghs [ 241 , 243246 ] .
immunoneutralization of ghrh and antagonists of ghrh also restrict ghs 's effects markedly , resulting in responses of somatotrope cells to ghs similar in magnitude to those in inferred directly in vitro [ 1 , 247 ] .
ghrelin or synthetic ghs achieves synergy with ghrh ( supraadditive stimulation of gh secretion ) when a near - threshold dose of ghs is combined with a maximally effective dose of ghrh in the human , rat , pig , cow , and dog in vivo [ 248255 ] .
synergism is not observed after combined stimulation with either maximal ghrh and maximal ghs or submaximal ghrh and maximal ghs stimulation [ 65 , 254 ] .
synergistic stimulation of gh release is absent in pituitary cells cultured in vitro and in patients with destructive lesions that separate the hypothalamus and pituitary gland [ 65 , 216 , 219 , 242 , 250 , 256 , 257 ] , thus defining a critical role for joint hypothalamopituitary effects .
proposed mechanisms include ghrelin - mediated ( a ) opposition to hypothalamopituitary actions of ss and/or ( b ) stimulation of an unknown ( u ) synergy factor [ 4 , 29 , 65 , 151 , 255 , 258260 ] .
a substance like galanin or an endogenous opiatergic peptide might represent such a factor , since both peptides release and synergize with ghrh and their neurons innervate periventricular ss neurons [ 261267 ] .
reduced pituitary action of ss is unlikely to be the sole potentiating mechanism subserving ghs action , since ghs and ghrh synergize even after immunoneutralization of ss .
although ghrh can induce the pituitary ghrelin and ghs - r1a genes , the physiological impact of this potentially amplifying mechanism is not known .
since highly selective ghs - r1a antagonists are not available for clinical investigation , determining the exact extent to which endogenous ghrelin participates in amplifying gh secretion in human physiology , including in utero , in infancy , childhood , puberty , adulthood , and senescence remains difficult [ 4 , 65 , 250 ] .
nonetheless , mutational reduction of constitutive ghrelin - receptor activity in humans is associated with short stature . conversely , overexpression of neuronal ghs - r1a in female mice elevates gh and ghrh gene expression .
in addition , prolonged administration of ghrelin or synthetic ghs in humans augments gh , igf - i and igfbp-3 concentrations and lean - body mass , and diminishes total - body fat , while eliciting transient secretion of adenocorticotropin hormone ( acth ) , cortisol , and prolactin [ 64 , 269273 ] .
the last observation is significant , because higher doses of ghrelin / ghs evoke acth , cortisol , and prolactin secretion acutely in humans and animals , putatively by inducing hypothalamic secretion of one or both primary acth - releasing peptides , corticotrophin - releasing hormone ( crh ) , and arginine vasopressin ( avp ) [ 272 , 274278 ] .
doubling or tripling plasma ghrelin concentrations evokes gh secretion in humans without measurably altering acth , prolactin , insulin , or free fatty - acid concentrations .
the basis for the dose - response difference and tachyphylaxis of the corticotropic , but not the gh - releasing , effect of ghs is not yet evident .
likewise , why age and obesity impair ghs - induced secretion of gh but not of acth and prolactin is not known [ 113 , 281 ] .
depending upon chemical structure and dose , synthetic ghs can stimulate gh secretion after intranasal , oral , s.c . , or i.v .
administration [ 4 , 65 , 250 , 272 , 282 , 283 ] .
entry of acylghrelin ( but not desacyl - ghrelin ) into and exit of the same from the brain is via structurally selective saturable transport [ 284286 ] .
since hypothalamic ghrh release is prerequisite to maximal gh stimulation , ghss have clinical therapeutic potential in treating : ( i ) idiopathic short stature in patients with preserved cns outflow of ghrh [ 64 , 287290 ] ; ( ii ) hyposomatotropism in aging , wherein ghrh release may be diminished but is not absent [ 271 , 291 , 292 ] ; ( iii ) hyposomatotropism associated with visceral adiposity , including the hiv lipodystrophy syndrome [ 167 , 179 , 190 , 293295 ] ; and ( iv ) conditions of partial gh resistance accompanying anorexia , cachexia , or heightened catabolism , such as metastatic cancer , hepatic or renal failure , chronic obstructive pulmonary disease , systemic inflammation , and advanced heart failure [ 133 , 250 , 296298 ] .
preclinical data in these areas and clinical data in healthy subjects suggest the merit and feasibility of more comprehensive investigations [ 270 , 271 , 299301 ] , since prospective , double - blind , placebo - controlled trials are lacking .
critical issues to be resolved include long - term safety , duration , efficacy , and indications for ghs administration in selected gh - deficient states .
short - term ghrelin / ghs administration stimulates gh secretion , locomotor activity , and appetite , increases plasma free fatty acids , imposes mild peripheral ( muscle ) insulin resistance , suppresses insulin secretion , inhibits fat oxidation , and promotes adipocyte glucose metabolism [ 4 , 65 , 170 , 209 , 210 , 302307 ] .
moreover , ghs is both antiproliferative and proliferative depending upon cell type [ 308310 ] . these and other multifaceted actions of ghrelin are discussed next .
ghrelin consistently enhances appetite by 25%30% in fasting humans and animals with the possible exception of chicken , quail , and sheep [ 37 , 39 , 295 , 311315 ] .
active ghrelin stimulates and suppresses glucose - sensitive neurons in the lateral and ventromedial hypothalamus , respectively , stimulating hunger and inhibiting satiety .
the orexigenic effect arises by combined activation of neuropeptide y / agouti - related peptide ( npy / agrp ) and orexin a neurons [ 314 , 318322 ] .
concomitantly , acylghrelin antagonizes satiety - promoting and anorexigenic signals , such as leptin [ 38 , 323 ] , corticotropin - releasing hormone ( crh ) , cocaine and amphetamine - regulated transcript ( cart ) , proopiomelanocortin ( pomc ) , and alpha - melanocyte - stimulating hormone ( alpha - msh ) [ 324326 ] : figure 5 .
agrp is an endogenous inhibitor of alpha - msh , thereby promoting positive energy balance .
ghrelin may act in part by inducing the intracellular signal mammalian target of rapamycin in agrp neurons , a messenger which promotes protein synthesis and limits apoptosis .
both npy and agrp participate in the orexigenic action of ghrelin , since transgenic disruption of both mediators is needed to quench appetite [ 303 , 321 ] .
the potent orexigen , orexin ( hypocretin ) , which is a key peptide in maintaining wakefulness , is also involved in the appetitive action of ghrelin , in that orexin - a immunoneutralization or receptor silencing attenuates ghrelin 's orexigenic action .
a key neuronal biochemical mediator of energy - depletion mediated appetitive drive may be the low - atp sensing protein kinase , amp kinase , which is stimulated by ghrelin and cannabinoids .
desacyl - ghrelin exerts opposite effects , namely . decreases food intake , fat mass , and gastric emptying [ 190 , 293 ] .
ghrelin also suppresses pancreatic beta - cell insulin secretion , which may contribute to orexigenesis , given that insulin can function as a cns satiety signal .
the peripheral vagus nerve and its dorsal motor nucleus in the brainstem and ventral tegmental neurons mediate some of systemic ghrelin 's appetitive effects [ 332336 ] .
hunger - suppressing vagal afferent impulses from the stomach are subdued by ghrelin and by other orexigenic hormones , acting via the ghs - r1a , cannabinoid-1 ( cb-1 ) , and melanin - concentrating hormone-1 ( mch-1 ) and activated by anorexigenic receptors , like cholecystokinin - a ( cck - a ) , peptide yy ( 336 ) , and glucagon - like peptide-1 [ 334 , 337 ] : figure 6 .
in fact , a cb-1 antagonist impedes ghrelin 's appetitive effect , illustrating key facilitative interactions .
in addition , a cck antagonist abolishes the capability of intraduodenal fat to suppress gastric ghrelin secretion , consistent with gastroduodenal feedback . the dorsal motor nucleus of the vagus expresses ghs - r1a , which modulates limbic - system dopamine- and brainstem gaba , glutamine , and noradrenergic transmission to hypothalamic appetitive and satiety centers [ 335 , 341343 ] .
dorsal vagal neuronal ghs - r1a levels may decline with aging in the rat .
ghrelin crosses the blood - brain barrier and directly inhibits leptin neurons and stimulates npy / agrp and orexin neurons , which are located , respectively , in the arcuate nucleu and lateral hypothalamus .
inhibition of brain ( rather than exclusively peripheral vagal ) ghs - r1a seems to explain the anorexigenic properties of ghrelin antagonists [ 346 , 347 ] .
although genetic disruption of ghs - r1a abrogates orexigenic stimulation by ghrelin , cachexia does not develop in the transgenic animals , including those with combined ghrelin and ghs - r1a knockout , putatively reflecting signal redundancy within nutritional networks [ 167 , 353355 ] . in particular
, pathways mediating orexigenesis and satiety are convergent , oppositional , adaptive , and complex [ 186 , 295 , 319 , 356358 ] , involving hormones from endocrine glands as well as gut mucosa and vagal afferent signals [ 35 , 38 , 359362 ] .
for example , intestinal mucosal l - cell - derived oxyntomodulin , a satiety signal , acts via the hypothalamus to inhibit vagally driven gastric secretion of acylghrelin , thus quelling hunger .
plasma leptin and ghrelin concentrations tend to vary inversely in various clinical settings , and cns leptin is a strong ghrelin antagonist , possibly by modulating npy - y1 or y5 signaling [ 8 , 38 ] .
ghs - r1a is subject to systemic modulation , including upregulation by thyroxine and e2 and downregulation by glucocorticoids and gh .
in addition , e2 inhibits the acute orexigenic effect of exogenous ghrelin in the male and female rat .
accordingly , the ghrelin system is a pivotal but nonexclusive member of a robust nutritional network in mammals [ 10 , 294 , 314 , 319 , 365368 ] .
however , ghrelin reduces food intake in neonatal chickens , possibly by elevating brain fatty - acid synthesis .
ghs receptors are located in the stomach , gastrointestinal myenteric plexus , vagal nodose ganglion , dorsal motor nucleus of the vagus , arcuate - nucleus orexigenic neurons , such as npy / agrp and orexin a - expressing cells , anorexigenic neurons that are either leptin - sensing or leptin - producing , and multiple other unidentified neurons [ 314 , 370 , 371 ] .
silencing any one of npy , agrp or orexin - a - receptor genes limits but does not abolish ghrelin 's orexigenic effect [ 329 , 372374 ] .
triple negation of npy , agrp , and orexin is necessary to eliminate ghrelin 's appetitive effect .
small interfering dna - mediated neutralization of paraventricular neuronal ghs - r1a in rats imposes weight loss and reduces serum ghrelin without altering food intake , suggesting effects on energy expenditure as well .
network robustness is conferred by the facts that ghrelin activates whereas leptin represses both npy / agrp , and orexin neurons ; orexin a potentiates ( feeds forward onto ) npy release via the orexin-1 receptor ; npy represses orexin release via npy - y1 receptors ; neuropeptide w and galanin - like peptide further modulate orexin neurons [ 377 , 378 ] npy and orexin , respectively , suppress ( feed back ) and induce ( feed forward onto ) the potent anorexigens , leptin , and proopiomelanocortin , which in turn feed back on ghrelinergic cells [ 186 , 235 , 379387 ] .
moreover , npy and ghrelin neurons synapse on themselves , suggesting autofeedback - dependent regulation .
collective feedforward / feedback circuits presumably subserve enhancement and suppression of food intake in a manner defined by sex , species , age , physical activity , ultradian rhythmicity , and sleep - wake cycles [ 35 , 231 , 295 , 328 , 388 ] . for example , sleep curtailment may augment appetite by simultaneously lowering circulating leptin and elevating ghrelin levels .
the latter correlates with meal initiation . these and other experiments illustrate the complex adaptability of nutritionally regulated neural networks [ 234 , 278 , 353 , 362 , 390 ]
. a 23-amino - acid c - peptidyl fragment of preproghrelin , named obestatin , has not fulfilled its original nomenclature as an antagonist of ghrelin 's orexigenic effects [ 394399 ] : figure 7 .
in addition , transgenic knockout of the proposed obestatin receptor , gpr39 , does not affect food intake [ 394 , 396 , 400 , 401 ] . whereas obestatin ( probably better termed , ghrelin - associated peptide ) does not alter pituitary hormone secretion , this peptide may suppress thirst , promote beta - cell survival and regeneration , activate urocortin-2 pathways and thereby inhibit gastroduodenal peristalsis , and induce early - response genes in gastric mucosa and preadipocytes [ 403410 ] .
a physiological distinction pertinent to cns actions of ghrelin , but not obestatin , is that only ghrelin exhibits specific saturable binding to and endocytosis by cerebral microvessel endothelial cells , thereby allowing measurable permeation of the blood - brain barrier [ 284 , 286 ] .
. transgenic overexpression of cns and gastric ghrelin causes hyperphagia , increases energy expenditure , and decreases sensitivity to insulin and leptin in mice .
the orexigenic action of ghrelin does not seem to wane in this model , since adult transgenic animals continue to eat excessively after fat depots reach a maximum . in a second model ,
8 weeks of ghs treatment maintained orexigenesis in the rat . in a third model , overexpression of ghs - r1a in ghrh neurons increased organ and muscle weight , while decreasing body fat in female animals .
conversely , in a fourth model , transgenic reduction of ghs - r1a expression on ghrh neurons suppressed both ghrh and npy gene expression , thereby diminishing gh and fat mass in the female . in patients with renal or cardiac failure or chronic lung disease and cachexia , short - term ( up to 3 weeks ) administration of ghrelin once or twice
daily may stimulate appetite and weight gain as assessed in uncontrolled studies [ 298300 , 414 , 415 ] .
however , in the perioperative orthopedic setting , ghrelin infusions for 3 weeks did not improve overall functional physical performance .
nonetheless , the precise extent to which ghs agonists and antagonists will alter hunger or satiety over the longterm remains difficult to forecast [ 74 , 232 ] .
this issue is important since studies with leptin , an anorexigenic adipokine that antagonizes ghrelin , revealed tachyphylaxis to satiety - promoting effects [ 186 , 417 ] .
ghrelin itself undergoes tissue - specific regulation by short - term fasting , hypoglycemia , and nutrient deprivation .
these factors depress brain ghrelin expression , while promoting gastric ghrelin secretion and amplifying cns responses to ghrelin [ 9 , 418 , 419 ] . in species
in which desacyl - ghrelin can antagonize the orexigenic effects of acylghrelin , regulation of goat activity in both the stomach and brain may be important to appetitive homeostasis [ 191 , 196 ] .
ghs analogs that do not require acylation have the merit of bypassing goat . gastric - bypass procedures , especially when combined with truncal vagotomy , often reduce serum total ghrelin concentrations initially [ 426 , 427 ] . in principle ,
reduced ghrelin availability would further attenuate adipogenesis [ 191 , 195 , 199 ] .
however , in some studies prolonged weight loss after gastric bypass had no effect on fasting ghrelin levels [ 250 , 428 , 429 ] or reduced only acylated ghrelin . in rodents
, vagotomy impedes both appetitive and gh - stimulating effects of ghrelin [ 334 , 336 , 431 , 432 ] . in humans ,
pharmacologic or surgical interruption of vagal cholinergic traffic lowers ghrelin concentrations and blunts appetitive stimulation but does not block ghs - induced gh release [ 336 , 431 , 433 ] .
ghrelin inhibits insulin ( beta cells ) and somatostatin ( delta cells ) but stimulates glucagon ( alpha cells ) , secretion in vivo and in isolated pancreatic islets in vitro [ 304 , 434439 ] .
inconsistencies may reflect the capabilities of desacyl - ghrelin to suppress hepatic glucose production and/or block acylghrelin 's inhibition of insulin secretion [ 198 , 221 , 434 , 441 ] .
other studies did not control for the fact that acutely elevated gh and glucose concentrations ( induced by ghs ) stimulate insulin secretion acutely .
ghrelin 's inhibition requires gi , which activates outward k currents and disables inward ca flux [ 443 , 444 ] .
moreover , acylghrelin antagonizes peripheral insulin action ( muscle > liver ) , which effect is reversed by desacyl - ghrelin in gh - deficient adults .
however , desacyl - ghrelin has little if any effect on glucose , insulin , free fatty acid , or gh releases in ( obese ) humans . from a reciprocal perspective , insulin and somatostatin
repress , whereas glucagon induces the gastric ghrelin gene in the rat [ 88 , 124 , 130 ] . in humans ,
in accordance with insulin 's negative effects , hyperinsulinemia associated with hepatic or skeletal - muscle insulin resistance and/or obesity correlates inversely with fasting ghrelin concentrations [ 71 , 447 , 448 ] .
an exception is the genetic prader - willi syndrome marked by obesity , mild insulin resistance , and unexplained hyperghrelinemia with increased numbers of gastric ghrelin - expressing cells [ 449451 ] .
adult pancreatic islets express relatively little ghrelin protein and few ghs receptors , but fetal and neonatal islets exhibit abundant ghrelin gene transcripts and peptide in epsilon cells [ 452454 ] .
although both acyl and desacyl - ghrelin promote beta - cell regeneration [ 408 , 455 ] , endogenous pancreatic ghrelin inhibits beta - cell function , since perfusion of the pancreas with ghrelin antiserum augments insulin secretion [ 408 , 438 , 444 , 456 ] .
in addition , genetic knockout of ghrelin and administration of ghs - receptor antagonists diminish fasting hyperinsulinemia and enhance glucose tolerance in rodent models [ 205 , 439 , 443 , 444 ] .
thus , in knockout ghrelin mice , increased constitutive ghrelin - receptor activity may result in increased insulin secretion , which would be susceptible to inhibition by a ghs receptor antagonist with inverse agonist activity .
further investigations are required to appraise the influence of diet , age , gender , species , and obesity on pancreatic actions of ghrelin , given the high importance of drug development in this area .
a desirable ghrelin antagonist would limit appetite , disinhibit insulin secretion , and minimize adiposity ( by favoring fat oxidation ) in patients at risk for the metabolic syndrome or type ii diabetes mellitus [ 84 , 205 , 223 , 457 , 458 ] .
table 4 highlights some of these issues and identifies potential adverse consequences of prolonged ghs - receptor blockade . at doses that induce maximal gh secretion , ghrelin and ghs can exert direct vasodilatory , cardiotropic , and brainstem - mediated hypotensive effects , typified by a 10%20% decrease in mean arterial blood pressure and an increase in left - ventricular ejection fraction [ 14 , 183 , 201 , 459464 ] .
desacyl - ghrelin also causes vasodilation and opposes cardiomyocyte and endothelial apoptosis [ 194 , 465 ] .
conversely , a ghrelin antagonist elevates heart rate and arterial pressure in the conscious rat .
the mechanisms of ghrelin 's effects include central suppression of sympathetic cardiac drive , systemic vasodilation , antagonism of angiotensin ii and endothelin - induced vasoconstriction including of the pulmonary arteries , and potentiation of nitric oxide - mediated relaxation of vascular smooth muscle [ 14 , 20 , 197 , 465471 ] : table 4 .
ghs receptors exist on endothelium , vascular smooth - muscle cells , and cardiomyocytes [ 13 , 201 , 472 , 473 ] .
furthermore , ghrelin transcripts and protein are expressed in endothelial cells and cardiac muscle [ 466 , 472 ] .
both ghrelin and desacyl - ghrelin reduce the rate of myocardial tension generation ( negative inotropic effect ) and the rate of tension relaxation ( negative lusitropic effect ) , possibly in part independently of the ghs-1a receptor [ 13 , 201 , 330 , 474 ] .
the membrane glycoprotein , cd36 initially recognized as a macrophage type b ldl - scavenger receptor and recently as a fatty - acid binding protein , may transduce or modulate certain cardiovascular and anti - inflammatory effects of ghrelin [ 188 , 207 , 474 ] .
the capability of ghrelin to limit apoptosis of endothelial cells and cardiomyocytes in vitro introduces the possibility of reducing endothelial dysfunction associated with atherosclerotic risk [ 476478 ] and salvaging myocardium in zones of marginal chemotoxicity or ischemia [ 22 , 194 , 461 , 480 ] .
increased coronary - artery perfusion pressure , reduced cardiac sympathetic activity , antagonism of l - type ca channel - mediated contractility , and activation of low - energy amp - kinase may contribute to cardiotropism [ 461 , 481 , 482 ] .
resultant effects are reduced left - ventricular endsystolic volume and increased cardiac output [ 414 , 460 ] : table 5 .
how much of this benefit is due to stimulated secretion of gh , which exerts cardiotropic effects , is not known .
elevated ghrelin concentrations in patients with chronic heart failure may indicate a compensatory mechanism in particular or reflect partial tissue resistance to ghrelin in cachetic states more generally [ 83 , 485 ] .
three- and four - week pilot studies of exogenous ghrelin 's anabolic and anticatabolic effects in chronic cardiac cachexia in the rat and human seem favorable [ 194 , 301 , 461 , 486 ] , although parallel - cohort prospectively randomized double - blind controlled clinical studies are not available .
collective data invite more rigorous interventional studies in experimental models of both early and advanced myocardial injury and failure .
in addition , further investigations are necessary to assess how ghs affects perfusion of the brain , skeletal muscle , kidney , liver , and intestine [ 296 , 487 ] .
ghrelin is expressed in granules in gastric x / a - like oxyntic cells [ 489 , 490 ] .
the same granules contain immunoreactive motilin , a comparably strong but distinct prokinetic peptide [ 491 , 492 ] .
obestatin is additionally present in many of the same cells , but its gastrointestinal function is not known [ 189 , 404 ] . in one report , obestatin was able to elicit pancreatic zymogen secretion . in other contexts , desacyl - ghrelin and obestatin , unlike ghrelin
ingestion of medium - chain triglycerides in the infant or adult enhances gastric acylghrelin concentrations [ 494 , 495 ] .
inactivation of prohormone convertase 1/3 ( a preproghrelin endopeptidase ) also increases ghrelin gene transcripts , suggesting negative feedback by ghrelin on its own transcription .
fasting induces the preproghrelin gene in fish and mammals via efferent vagal cholinergic signals [ 497499 ] .
the cephalic ( meal - visualization ) phase of digestion in humans clearly depends on vagal efferents , which transduce prandial inhibition of ghrelin secretion . in sheep ,
cholinergic blockade stimulates stomach ghrelin output , suggesting baseline cephalic phase - like inhibition in this species .
motilin and ghrelin receptors are 36% homologous in peptide sequences ; yet each is activated principally by the homologous agonist at physiological concentrations [ 492 , 501 , 502 ] .
the ghs - r1a gene is conserved with 58% nucleotide homology in puffer fish and humans .
the receptor is present in the myenteric ( neuronal ) plexus , gastroduodenal mucosa , smooth muscle , and vagal nodose ganglia [ 503 , 504 ] .
ghrelin stimulates smooth - muscle contractions and type iii primary migrating - motor complexes in the stomach and proximal duodenum of the eel , rat , rabbit , mouse , guinea pig , and human ; inhibits postprandial contractions ( dog ) and gastric accommodation ( decreases residual stomach volume ) ; and promotes gastric - acid secretion , which facilitates protein hydrolysis and ca absorption [ 505511 ] .
current promotility drugs for the treatment of idiopathic , postvagotomy and diabetic gastric atony , and morphine - induced postoperative ileus include serotoninergic-3 agonists , dopamine antagonists , and motilin - receptor agonists , like erythromycin [ 492 , 512514 ] . whereas desacyl - ghrelin may block certain promotility effects of ghrelin , ghrelin is unique in acting on all four of gastroduodenal myenteric neurons , smooth - muscle cells , the vagus nerve , and brain ghs-1a receptors to augment gastric emptying and lower ph [ 333 , 512 ] .
histamine-2 agonists and gastrin synergize in promoting preprandial acid secretion [ 516 , 517 ] , thus illustrating intragastric interactions with ghrelin .
preclinical and clinical data indicate that ghs - receptor agonists can accelerate gastric emptying even in the presence of autonomic denervation , and reduce postoperative gastrointestinal ileus [ 492 , 506 , 509 , 511 , 512 , 518522 ] .
patients with diabetic gastroparesis may have low plasma total ghrelin levels , possibly due to vagal denervation and/or chronic glucagon excess [ 121 , 523 , 524 ] . what is unclear is the risk / benefit ratio of systemic ghs treatment in patients with gi bleeding , autonomic neuropathy , and/or concurrent postoperative needs for narcotics , anticholinergics , and other drugs . concerns would include possible hypotension due to ghs - mediated relaxation of vascular smooth muscle and negative cardiac inotropy and possible deterioration of glucose tolerance due to suppression of insulin secretion and augmentation of hepatic glucose output .
. viewed conversely , ghrelin administration enhances slow - wave ( non - rem ) sleep including in young and older men but not women [ 526530 ] . in one clinical study ,
the ghs peptide , hexarelin , reduced non - rem sleep whereas ghrp-6 increased the same , suggesting ghs - receptor pleiotropy or multiplicity .
how ghrelin can enhance deep sleep and yet activate orexin - a neurons , which are coupled to arousal - wakefulness and appetite , is not yet clear [ 328 , 532 ] .
in addition , why patients with obstructive sleep apnea , albeit obese , have elevated acylghrelin concentrations has not been elucidated . however , reduction of hypoxic episodes decreased ghrelin , suggesting that ghrelin is a stress - responsive hormone .
ghrelin and ghs analogs exert differentiative as well as proliferative and antiproliferative effects in vitro and in vivo [ 193 , 211 , 455 , 534 ] .
examples include mitogenic and antiapoptic actions on pancreatic islets , spinal - cord , cortical and brainstem neurons , osteoblasts , fetal lung branches , endothelium , cardiomyocytes , and adipocytes on the one hand , and apoptotic effects in certain adrenal , lung , and prostate cancer cell lines on the other hand [ 15 , 21 , 22 , 192 , 211213 , 309 , 391 , 480 , 535541 ] .
several cell - cycle effects can be induced by incubation with either acyl- or desacyl - ghrelin , raising the possibility of involvement of both ghs - r1a and non - ghs - r1a receptor pathways [ 58 , 537 ] .
this reflects the fact that ghs-1a is essentially unresponsive to desacyl - ghrelin [ 22 , 177 ] .
short - term ghrelin / ghs administration to enhance neuronal regeneration after ischemic or toxic insults thus represents another major point of potential therapeutic focus [ 214 , 542 , 543 ] . because ghrelin can also stimulate proliferation of certain carcinoma cell lines in vitro [ 308 , 309 , 544 ] , studies to exclude longterm oncogenic effects
inasmuch as appetite wanes in the cachectic stage of carcinomatosis , ghrelin is being evaluated as an anticachectic agent .
studies in the rat , mouse , and human indicate that ghrelin / ghs administration can dose - dependently enhance appetite , body weight , and fat mass in several short - term models of disseminated neoplasia [ 545549 ] .
caveats are that rigorous controls and blinding are often lacking , and evaluations are necessarily of short duration initially .
in addition , some studies do not show orexigenic benefits [ 550 , 551 ] .
a preliminary study in 12 cachectic patients with dialysis - dependent kidney failure showed appetitive enhancement by ghrelin compared with randomized double - blind placebo injection over a 1-week interval .
prominent effects of ghrelin / ghs include direct promotion of preadipocyte proliferation and adipocytic differentiation and hypertrophy [ 76 , 552 ] : table 6 .
desacyl - ghrelin shares several of these actions [ 191 , 199 ] . relevant mechanisms embrace repression of insulin - sensitizing genes , such as adiponectin , and induction of adipocyte leptin and peroxisome - proliferating activator receptor- ( ppar- ) gamma genes ; stimulation of endothelial lipoprotein lipase , adipocyte fatty acid synthase , acetyl coa carboxylase , and fat - cell glucose uptake ; and inhibition of fat oxidation via rate - limiting carnitine - palmitoyl transferase [ 167 , 171 , 172 , 191 , 554 , 555 ] . as a more general metabolic mechanism ,
ghrelin mediates inhibition of sympathetic outflow to thermogenic fat depots , reduction of uncoupling protein-1 expression , and thereby decreased resting energy expenditure [ 556 , 557 ] .
for example , in sheep , ghrelin potentiates glucose - induced insulin secretion , which is antilipoytic .
cns pathways may participate in stimulating adipocyte hypertrophy and increasing the respiratory coefficient ( increased ratio of glucose / fatty - acid oxidation ) [ 234 , 392 , 555 ] . in particular , ghrelin acts in part by repressing leptin , crh , and histamine ( anorexigenic ) and activating orexin and npy ( appetitive ) signaling [ 184 , 559561 ] .
orexin a in turn inhibits ghrh gene expression , thus limiting gh - dependent lipolysis .
thus , orexin contributes to fat accumulation by augmenting appetite , attenuating satiation , and restricting gh secretion [ 38 , 171 , 443 ] . despite ghrelin 's strong adipogenic effects , subcutaneous , visceral , and total
. this may be because a significant longterm effect of ghrelin is to drive pulsatile gh secretion , which is strongly lipolytic .
animal models indicate that ghrelin antagonists are able to reduce hyperglycemia and adipogenesis , enhance energy expenditure and fat oxidation , stimulate insulin secretion and action , and heighten resistance to diet - induced obesity [ 167 , 168 , 179 , 182 , 184 , 205 , 564 ]
. a potential risk of prolonged antagonist administration in the fasting state could be endogenous insulin - induced hypoglycemia , although this adverse event has not been observed in humans .
ghs - r1a and ghrelin peptide are synthesized in bone cells , such as chondrocytes and osteoblasts [ 12 , 565 ] .
albeit moderately well understood in other tissues , mechanisms mediating regulation of ghs - r1a in bone remain unclear : table 7 .
acylated and unacylated ghrelin stimulate osteoblast proliferation and differentiation , increase osteoblastic markers like osteocalcin and bone alkaline phosphatase , and repress osteoblast apoptosis putatively via phosphatidylinositol 3-kinase and mitogen - activated protein kinase signaling .
moreover , in gh - deficient rodents , ghrelin administration augments ca retention in the skeleton , thereby elevating bone - mineral density .
recent studies point to a role for ghrelin in modifying pathophysiological adaptations to stress [ 275 , 567 , 568 ] . for example , ghrelin concentrations rise acutely after major surgery along with inflammatory cytokines like tumor - necrosis factor - alpha and interleukin ( il)-6 . in mice , transgenic knockdown of the ghrelin receptor accentuates adverse effects of chronic social - defeat stress .
analogously , ghrelin may permit adaptation to pain , since it blocks spinal - cord nociceptive signals .
lipopolysaccharide endotoxin stress lowers blood ghrelin levels , causing an associated reduction in gastric emptying . the latter is substantially relieved by ghrelin infusion . under some conditions ,
desacyl - ghrelin inhibits gastric contractions by activating stress - adaptive crh receptor-2 , for which urocortin is the natural ligand [ 208 , 348 ] .
ghrelin also induces the anorexigenic hypothalamic crh gene , which normally stimulates acth release . whether cns - mediated inhibition of food intake by desacyl - ghrelin proceeds by activating the crh pathway is not known .
this peptide induces nitric oxide synthase ( nos ) and represses the generation of reactive oxygen species , thereby attenuating endothelial injury [ 20 , 573 ] .
the protective effects require ghs - r1a , phosphotidylinositol-3 kinase , and akt / protein kinase b .
ghrelin can also directly stimulate human vascular endothelial - cell migration , but the impact of this effect is not so clear . substantial additional work is needed to extend understanding of these aspects of ghrelin pathophysiology .
ghrelin , ghs receptors , gh , and gh receptors are expressed in human monocytes and b and t lymphocytes . in general ,
ghrelin 's effects are antiinflammatory and immune - enhancing , for example , diminution of monocytic , bacterial and endothelial inflammatory factors driven by endotoxin exposure , sepsis , arthritis , interleukin 1 and 6 , tumor necrosis factor - alpha , and nuclear - factor kappa b [ 200 , 577579 ] , and stimulation of proliferation of thymic epithelial cells and t lymphocytes [ 580 , 581 ] .
ghrelin also suppresses neutrophil and macrophage migration , caspase activation , reactive oxygen - species generation , and endoplasmic - reticular stress activation [ 582584 ] .
the combined impact may be to restrict lethal hepatic and pulmonary microvascular injury in sepsis [ 515 , 585587 ] .
ghrelin concurrently induces antiinflammatory cytokines , like interleukin-10 , and augments organ perfusion pressure in sepsis [ 515 , 588 ] .
sepsis - associated gastric mucosal injury , an additional cause of mortality due to hemorrhage , is prevented in some models .
certain of these effects may require the vagus nerve . in acute renal failure , ghrelin treatment can repress inflammatory cytokines in the blood and brain , limit protein catabolism , enhance food intake , and attenuate renal injury due to endotoxemia and ischemia [ 415 , 591594 ] .
total but not acylghrelin concentrations are elevated in endstage renal failure and normalize following kidney transplantation .
long - term surveillance of ghrelin and ghs receptor - deficient and ghrelin - overexpressing transgenic animals will be needed to assess whether prolonged changes in ghrelin availability influence immune function or inflammatory disease .
although acute stress elevates gh secretion , extended critical illness suppresses all three of gh , igf - i , and igfbp-3 concentrations and inhibits tissue actions of gh . in unfed patients with multiorgan failure , total ghrelin levels rise [ 86 , 131 ] .
infusions of ghs alone or combined with ghrh substantially reverse biochemical markers of hyposomatotropism in this setting [ 597 , 598 ] .
however , recovery from multiorgan failure and inflammation is necessary to alleviate tissue resistance to gh . in animal models
, ghrelin administration reduces sympathetic outflow , acute renal failure , inflammation in the lung , stomach and liver , and lethality of sepsis [ 200 , 344 , 515 , 586590 , 599601 ] .
contrastingly , glucocorticoid deficiency , and glucocorticoid excess alter the ghs axis by , respectively , diminishing blood ghrelin and brain ghs - r1a levels [ 421 , 602 , 603 ] .
ghrelin is expressed abundantly by the placenta , and ghrelin can stimulate gh release by human fetal pituitary cells in vitro .
immunoneutralization of maternal ghrelin in the rat diminishes fetal body weight , raising the possibility of maternal - fetal exchange of ghrelin . maternal ghrelin and
placentally derived variant - gh concentrations in the human peak at about 18 and 34 weeks gestation , respectively , fall thereafter , and reach a nadir approximately 3 days postpartum [ 607609 ] .
the decline in ghrelin in the third trimester of pregnancy is inversely related to blood pressure , resistin , and tnf - alpha levels [ 95 , 610 ] .
although human umbilical - cord acylghrelin levels exceed those in the mother , the role of placental ghrelin is not well understood .
placental insufficiency , low birth weight , and maternal fasting elevate fetal ghrelin levels [ 611 , 612 ] .
postpartum acylghrelin concentrations increase by several - fold over midpregnancy values , but gh responses to ghs are reduced in breastfeeding women , especially in the hyperprolactinemic setting .
the basis may involve pregnancy - associated suppression of hypothalamic ghrh and ghs - r1a with reciprocal induction of the ss gene due to feedback by high placental somatomammotropin ( gh isotype v ) and maternal igf - i concentrations . in the rat
pituitary ghs - r1a is maximal in the newborn pup and pubertal animal : table 7 .
estradiol , t4 , and ghrh may contribute to these maxima , since the ghs - r1a promoter is responsive to estrogen and cyclic amp [ 122 , 187 ] .
ghrelin is secreted into colostrum and milk , but its effect on the suckling infant is not well delineated . in one preclinical study , treating rat pups with
exogenous ghrelin reduces lh pulse frequency in the adult male rat , cyclic or gonadectomized female rat , and ovariectomized monkey [ 618622 ] .
ghrelin may also inhibit embryo development , decrease litter size , and delay pubertal onset in the male rat [ 623 , 624 ] .
the mechanism may involve neuropeptide y ( y1 or y5 ) or crh - dependent inhibition of kisspeptin , which together supervise gonadotropin - releasing hormone secretion , and thereby pulsatile lh secretion [ 622 , 624627 ] .
other sites of inhibition may include uterine epithelium ( by inducing igfbp-1 and lowering free igf - i ) , leydig cells in the testis , and granulosa - luteal cells in the ovary ( by blocking steroidogenesis ) [ 624 , 628633 ] .
although physiological effects are not clear , ghrelin is expressed in sheep oocytes , and ghs - r1a in sertoli ( nurse ) cells in spermatogenic tubules .
for example , ghrelin infusion had no demonstrable effects on lh secretion in the early follicular phase of the menstrual cycle .
both ghrelin and obestatin are detected in various neoplasms , such as enterochromaffin tumors ( e.g. , carcinoids ) , pituitary adenomas , and carcinoma of the pancreas , lung , and breast [ 406 , 636 , 637 ] .
the amount of peptide secreted is usually insufficient to serve as a tumor marker or to elicit clinical symptoms or signs .
clinical studies in older individuals indicate that prolonged ( up to 1 year ) administration of ghs orally can increase lean - body mass , decrease abdominal visceral fat , and possibly improve certain performance measures , such as stair climbing and timed walking [ 548 , 638 ] . in analyses comprising 1-to-30 days of parenteral ghs delivery , igf - i concentrations also rise , but cortisol and prolactin do not [ 270272 ] : figure 8 .
adverse events included insomnia , fatigue , small increases in fasting glucose or glycated hemoglobin , and mild insulin resistance .
an important consideration is that acute diabetogenic effects of ghs may be attenuated by its longterm antidiabetic effects : table 8 .
insomnia could reflect ghs 's stimulation of orexin pathways , whereas glucose intolerance could reflect insulinostasis and insulin resistance due to acute free fatty - acid release in humans .
short - term use of ghrelin in severe cachexia enhanced appetite and/or weight gain in some studies [ 298 , 300 ] .
whereas both glucocorticoid deficiency and excess in chronic diseases can reduce gh response to ghs [ 4 , 421 ] , combined ghrh and ghrelin infusion is more effective at driving gh secretion than ghrelin alone : figure 8 . viral vector delivery of ghrelin augmented weight in the rat , introducing an additional potential avenue of treatment beyond subcutaneous , intravenous , oral , or intranasal administration .
a small percentage of gh - deficient adults ( 10% ) also respond acutely to ghs , suggesting some preservation of somatotrope function and ghrh availability .
in other settings , injected ghs showed high specificity ( 95% ) but low sensitivity ( 80% ) in detecting gh deficiency . combining ghs with ghrh and/or l - arginine improves test sensitivity [ 4 , 163 ] .
species differences in ghrelin structure , and to a lesser degree ghrelin action , have been articulated [ 2 , 26 , 62 , 276 , 315 , 642 ] . in the eel
epidemiological studies have not identified common genetic haplotypes of ghs - r1a , which predispose to obesity or short stature .
two - weak associations of ghs - r1a polymorphisms with metabolic syndrome or cardiovascular risk require confirmation [ 646 , 647 ] .
similar preliminary data apply to polymorphisms of the ghrelin gene [ 393 , 648 ] .
in addition to increasing gh , as the term ghrelin implies , ghs regulates inflammation , cellular proliferation , apoptosis , differentiation , and hormone secretion via receptors located in the brain , stomach , intestine , heart , arterial wall , bone , fat cells , and pancreas ( exocrine and endocrine ) .
acylated and unacylated ghrelin can exert both similar ( antiapoptotic ) and opposite ( appetitive ) effects .
promising clinical applications of ghrelin agonists and antagonists arise in relation to metabolic , gastric , gh - stimulating , anti - inflammatory , and cardiotropic effects .
nonetheless , there are both desirable and potentially undesirable aspects of chronic administration of ghrelin agonists or antagonists : table 9 . accordingly
a saga is evolving within the ghrelin system due to the recent identification of the ghrelin o - acyl transferase ( goat ) enzyme [ 47 , 48 ] .
not only is ghrelin the first natural hormone with a fatty - acid addition , but also octanoylation is essential for binding and activating the receptor , ghs - r1a , probably by determining the active receptor - specific conformation of the ghrelin 128 molecule
. final isolation of the goat enzyme may not be so easy , since it is tightly bound by 12 transmembrane domains spanning the endoplasmic reticulum ( er ) .
important issues arise regarding the chemistry and biology of posttranslational octanoylation of ghrelin hormone .
the current concept is that preproghrelin 1117 or proghrelin 194 is octanoylated for fundamental biological reasons . in consonance with this postulate , production of octanoylated ghrelin 128
is restricted to the conjoint anatomical and intracellular sites of goat and preproghrelin 1117 biosynthesis .
furthermore , if the desacylated ghrelin 128 is not directly octanoylated by goat , the specificity of biological regulation is made even more precise .
available evidence indirectly suggests that goat first octanoylates the preproghrelin 1117 or the proghrelin 194 molecule . in the former case
subsequently , several prohormone convertases ( pc1/3 , pc2 , and furin ) permit sequential formation of octanoylated ser proghrelin 194 and octanoylated ser ghrelin 128 [ 496 , 649 , 650 ] .
before the identification of goat , zhu , cao , voogd , and steiner published the finding that 194 proghrelin was octanoylated , whereas ghrelin 128 remained unoctanoylated .
these results support the inference that octanoylated ser ghrelin 128 is derived from octanoylated proghrelin 194 .
zhu et al . demonstrated that pc1 must be the enzyme that cleaves proghrelin in vivo , because only proghrelin and not processed ghrelin is made in pc1-knockout mice .
in addition , furin can cleave proghrelin in vitro as described in the laboratory of lindberg and , more recently , that of kojima in transfection studies [ 72 , 649 ] .
why furin does not suffice in the pc1 gene - deletion model is not clear .
in addition to goat , another human er oxyesterase has been purified and characterized from a stable human erythroleukemia cell line by ozawa , speaker , and lindberg .
the acronym of this additional oxyesterase is erat for endoplasmic reticulum o - acyl transferase .
erat will esterify modified proghrelin having an n - terminal tripeptide extension , but not the proghrelin 194 molecule .
notably erat octanoylation is limited to the ser amino - acid residue , while ser , ser , or ser of ghrelin 128 are not octanoylated .
in addition , erat may transfer an array of long - chain natural fatty acids , not just octanoic , to as yet unknown substrates as well as to ghrelin 128 , when the latter contains an n - terminal tripeptide extension .
furthermore , erat is a soluble enzyme , but firmly bound to the er membrane , whereas goat is an insoluble integral er membrane - spanning enzyme .
if erat and goat were colocalized in the human stomach , one could envision both independent and interdependent roles of erat and goat .
although mammalian goat was initially considered to only add octanoic or decanoic fatty acids to ser , the laboratory of kojima reported that goat effectively acylates truncated ghrelin peptides with n - hexanoic acid in cultured cells .
a significant analytical point is that ser versus ser octanoylated ghrelin would not be distinguishable by mass spectrometry , hplc , or probably immunologically , requiring instead mutagenesis studies , amino - acid sequencing , binding , and biological activity studies .
albeit low in potency , ser dioctanoylated ghrelin 128 can release gh in vivo in rats .
in addition , scientists at merck laboratories demonstrated that ser mono - octanoylated ghrelin 128 binds to ghs - r1a in vitro .
since octanoylated ghrelin 128 may exert endproduct repression of goat acyltransferase activity and since binding sites for goat , erat , and ghs - r1a may overlap , small amounts of ser or ser octanoylated ghrelin 128 might have goat inhibitory activity .
the proposition would be that endogenous erat - derived ghrelin peptides may act on goat only at intracellular sites .
notable are two ghrelin deacylation enzymes , plasma paraoxanase and gastric lysophospholipase i [ 156 , 651 ] .
plasma paraoxanase is bound to high - density lipoproteins and may especially determine physiological plasma ghrelin levels . an interesting question is whether a major role of blood - borne paroxanase is to minimize the actions of octanoylated ghrelin or to maximize the actions of desacylated ghrelin . on the other hand , gastric lysophospholipase i may primarily regulate tissue ghrelin bioactivity and subsequent vagal - afferent activity as a function of the amount and type of oral fatty - acid intake . in this
regard , oral octanoate increases , but oral dodecanoate decreases , plasma octanoylated ghrelin levels .
accordingly , the activity of the two deacylases could be a function of amount and type of substrate as well as factors that modify synthesis of and catalysis by paroxanase and lysophospholipase i. the multiple influences of the ghrelin system depend upon local and systemic posttranslational regulatory mechanisms and pleiotropic receptor - signaling in diverse target tissues .
moreover , gastric ghrelin is subject to food - entrainable and circadian - clock inputs .
there is an additional possibility that partial overlap of ghrelin - binding properties of ghs - r1a , goat , and erat could contribute to differences and similarities between ghrelin and ghs mimetics as well as competition between full and partial ghs - r1a agonists .
brown and goldstein demonstrated that truncated ghrelin peptide analogs inhibit activity of goat in vitro .
they proposed that native octanoyl ghrelin 128 in higher concentrations may also inhibit goat .
if so , one could envision that certain ghs mimetics might decrease or increase the activity of goat and erat as well as that of ghs - r1a .
for example , at a low dosage dap octanoylated ghrelin 128 inhibits octanoyl transferase activity in vitro indicating that goat is a significant site of action , whereas this analog stimulates both gh release and food intake in vivo , thus defining a ghs - r1a ( ghrelin receptor ) site of action [ 46 , 654 ] . to assess the biochemistry , physiology , endocrinology , and therapeutic implications of peptide / non - peptide ghs mimetics and ghrelin will require combined in vitro and in vivo structure - function and dose - response analyses .
Output:
| oligopeptide derivatives of metenkephalin were found to stimulate growth - hormone ( gh ) release directly by pituitary somatotrope cells in vitro in 1977 .
members of this class of peptides and nonpeptidyl mimetics are referred to as gh secretagogues ( ghss ) . a specific guanosine triphosphatate - binding protein - associated heptahelical transmembrane receptor for ghs
was cloned in 1996 .
an endogenous ligand for the ghs receptor , acylghrelin , was identified in 1999 .
expression of ghrelin and homonymous receptor occurs in the brain , pituitary gland , stomach , endothelium / vascular smooth muscle , pancreas , placenta , intestine , heart , bone , and other tissues .
principal actions of this peptidergic system include stimulation of gh release via combined hypothalamopituitary mechanisms , orexigenesis ( appetitive enhancement ) , insulinostasis ( inhibition of insulin secretion ) , cardiovascular effects ( decreased mean arterial pressure and vasodilation ) , stimulation of gastric motility and acid secretion , adipogenesis with repression of fat oxidation , and antiapoptosis ( antagonism of endothelial , neuronal , and cardiomyocyte death ) .
the array of known and proposed interactions of ghrelin with key metabolic signals makes ghrelin and its receptor prime targets for drug development . |
PubmedSumm118605 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
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the input is a biomedical literature
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the output is the summary of an input biomedical literature in six sentences
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Input:
Output:
| male rats were exposed to 10 consecutive days , 6 hr / day , to vinyl chloride vapors at an average concentration of 13,500 ppm .
the exposed rats were divided into three groups of eight rats each : one group was pretreated with 3-methylcholanthrene , one group was pretreated with phenobarbital , and the third group received no treatment .
half the animals in each group were sacrificed 18 hr after the last exposure and half were sacrificed 4 days later . in a second experiment , four rats pretreated with phenobarbital were exposed to vinyl chloride vapors at a concentration of 17,300 ppm for 2 days and sacrificed about 9 a.m. on the third day . in both experiments control animals , also treated with phenobarbital or 3-methylcholanthrene , were exposed to air only . at the time of sacrifice
, lungs , kidneys , spleen , heart , and a small piece of liver from each animal were preserved for histological examination .
the remainder of the liver was processed for assay of microsomal enzyme activity .
the following parameters were investigated : growth rate , organ weights , morphological changes , and both benzphetamine - n - demethylase activity and cytochrome p-450 content of microsomes prepared from the livers . in both experiments
the only marked difference noted in any group was a decrease in the growth rate of the animals exposed to vinyl chloride and treated with phenobarbital .
this decreased growth rate was particularly apparent on the third day of the vinyl chloride exposures .
occasional morphological changes were also seen in the livers of the animals treated with phenobarbital and exposed to vinyl chloride.imagesfigure 2.figure 3 . |
PubmedSumm118606 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: polycystic kidney disease ( pkd ) is the most common cause of monogenic inherited kidney disease and is associated with extrarenal manifestation of cystogenesis in other organs including liver and pancreas , saccular aneurysm in central nervous system vasculature and mitral valve disease . the genetic basis for this has been identified as mutations in one of two large proteins , polycystin 1 and 2 [ for review
the penetrance is highly variable in that cysts and chronic kidney disease may develop at different ages within the same family with identical mutation .
the reasons for this are unclear and various hypotheses have been advanced to address this observation [ 4 , 5 , 6 ] .
in addition to cyst formation , manifestation of kidney disease includes subnephrotic proteinuria , microscopic and macroscopic hematuria ; nephrotic - range proteinuria ( > 3 g / day ) is uncommon .
acute renal failure secondary to rapidly progressive glomerulonephritis is rare and , thus far , only 1 case has been described .
we report a case of crescent , rapidly progressive glomerulonephritis in a patient with pkd .
a 43-year - old man presented to the emergency department complaining of lower extremity edema for 2 weeks .
the patient denied any pertinent past medical or family medical history ; though he took metoprolol and hydrochlorthiazide for about 1 month a year earlier , he was not taking either of these agents at the time of presentation .
he denied use of nonsteroidal anti - inflammatory agents and recreational drugs ( including cocaine , heroin and phencyclidine ) .
initial physical examination was significant for elevated blood pressure ( 151/94 mm hg ) and pitting edema in both lower extremities .
initial laboratory analysis at presentation ( table 1 ) revealed renal failure ( serum creatinine 2.6 mg / dl ) and anemia ( hemoglobin 10.8 g / dl , hematocrit 33.4% and mean corpuscular volume 85.4 fl ) .
urinalysis ( random urine ; table 2 ) showed proteinuria , small blood and pyuria without bacteria .
proteinuria was confirmed on 24-hour urine collection that demonstrated nephrotic - range protein ( 25 g/24 h ) .
kidney ultrasound revealed enlarged kidneys bilaterally with multiple cysts and this was confirmed by computed tomography ( ct ) scanning ( fig .
a complete serologic evaluation , including hepatitis screen , was performed and was unrevealing ( table 2 ) .
initially , the patient was empirically treated with intravenous steroid pulse ( methylprednisolone , 1 g daily for 3 days ) and then switched to prednisone orally ( 1 mg per kilogram daily ) . a ct - guided kidney biopsy was performed and revealed immune complex glomerulonephritis with features of membranous nephropathy with crescent formation ( fig .
despite treatment with oral prednisone ( 1 mg / kg ) , the patient 's renal function declined and he became oliguric .
in addition to oral steroid , treatment with mycophenolate ( 500 mg twice daily ; escalated to 1,500 mg twice daily over 2 weeks ) was started . over a 5-month period ,
concurrently , serum albumin recovered to normal values and proteinuria decreased from 25 to 3 g daily . because of persistent nephrotic - range proteinuria , cyclosporine 75 mg twice daily was added to his medication regimen . over the ensuing 3 months , the patient manifested further improvement in physiologic parameters .
accordingly , prednisone dosage was reduced ( 10 mg orally per day ) and mycophenolate mofetil ( mmf ) was maintained at 1,500 mg orally twice daily and cyclosporine at 75 mg orally twice daily .
hemodialysis was subsequently discontinued and the patient has been off dialysis with stable chronic kidney disease stage 3 ( creatinine clearance 45 ml / min by 24-hour urine studies ) .
he continues to be monitored closely in an outpatient setting for any changes in renal function .
in patients with autosomal dominant polycystic kidney disease ( adpkd ) , nephrotic - range proteinuria is an uncommon occurrence .
however , when this has been reported , various etiologies have been identified , including membranous glomerulonephritis , focal and segmental glomerulosclerosis , minimal change disease [ 8 , 9 , 10 ] and immunoglobulin a ( iga ) nephropathy [ 11 , 12 ] . of these ,
focal and segmental glomerulosclerosis appears to be the most frequently reported cause of nephrotic - range proteinuria in those with adpkd who develop proteinuria [ 8 , 13 ] .
proliferative glomerulonephritis , including iga nephropathy , is a less common cause of nephrotic syndrome [ 11 , 14 ] .
crescentic glomerulonephritis is a rare occurrence in those with pkd and has only been reported once in the literature .
all reported series emphasize the importance of performing kidney biopsies in patients with pkd who develop nephrotic - range proteinuria .
in addition to identifying the cause of massive proteinuria in this population , renal biopsy informs appropriate management of proteinuria in affected individuals . in the current case ,
the cause of acute kidney injury and nephrotic syndrome was identified as crescentic glomerulonephritis rather that the patient 's underlying pkd .
in addition , the findings on biopsy were important in guiding a more aggressive immunosuppressive regimen in the management of the patient .
the reason(s ) for the occurrence of glomerulopathies , with massive proteinuria , in adpkd remain unclear . in the current case ,
common causes of rapidly progressive kidney failure and nephrotic - range proteinuria , including postinfectious causes , hepatitis b and c and iga nephropathy were excluded .
given the rarity of rapidly progressive crescent glomerulonephritis in those with pkd , there are no established guidelines on management . because pkd in this patient was diagnosed on this presentation and in view of rapidly progressive glomerulonephritis , management of the latter is the primary goal .
the combination of steroid and mmf was chosen over steroids and cyclophosphamide because of a better side effect profile .
this case also illustrates the importance of a prompt diagnosis of nephritic syndrome in patients with pkd , especially when there is an acute deterioration of kidney function , information that can not be obtained from conventional imaging and serologic analyses .
Output:
| polycystic kidney disease is an inherited condition , characterized by the development of cysts in the kidney , as well as in other organs .
patients with polycystic kidney can suffer from the same causes of acute kidney injury as the general population .
nephritic syndrome is an uncommon cause of acute kidney injury in the general population and less common in patients with polycystic kidney disease .
we report the second case of crescentic glomerulonephritis , causing acute kidney injury , in a patient with polycystic kidney disease . |
PubmedSumm118607 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: the forebrain region known as the nucleus accumbens ( nac ) functions to prioritize emotional and motivational arousals for behavioral output .
these emotional and motivational arousals are thought to be carried out and regulated by excitatory projections from several limbic and paralimbic regions , including the ventral tegmental area , prefrontal cortex , amygdala , hippocampus , thalamus , hypothalamus , and other regions ( wise , 1987 ) .
these excitatory projections undergo adaptive changes after exposure to cocaine or other drugs of abuse , and many of these drug - induced alterations in nac glutamatergic transmission are essential for the expression of addiction - associated behaviors ( wolf , 1998 , 2010 ) .
a prominent form of cocaine - induced circuitry remodeling is achieved via generation and subsequent evolution of -amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor ( ampar)-silent excitatory synapses .
silent excitatory synapses are synapses that express stable n - methyl - d - aspartate ( nmda ) receptor ( nmdar)-mediated postsynaptic responses , while ampar - mediated responses are minimal ( kerchner and nicoll , 2008 ; hanse et al . , 2013 ) .
at the resting membrane potential , because nmdars conduct little current , these synapses are largely silent .
electrophysiologically , ampar - silent , nmdar - only synapses are demonstrated as synapses that are inactive at near - resting membrane potentials due to mg - mediated blockade of nmdars , and active at depolarized membrane potentials , at which mg - mediated blockade of nmdars is relieved .
the percentage of silent synapses among all examined synapses can also be estimated using several electrophysiological approaches ( isaac et al . , 1995 ; liao et al . , 1995 ; huang et al . ,
silent synapses can be generated by insertion of nmdars to new synaptic contacts via a synaptogenesis process , and may undergo a subsequent un - silencing process through recruiting ampars to stabilize the synapses .
silent synapses can also be generated by removal or desensitization of ampars from existing excitatory synapses , and these destabilized synapses may be pruned away subsequently .
silent synapses are abundant during circuitry development and decline to very low levels after development ( durand et al . , 1996 )
. the generation of silent synapses and subsequent maturation or elimination of these synapses may not only strengthen or weaken the overall excitatory synaptic transmission but also redefine the anatomical architectures of affected circuits , leading to profound circuitry remodeling .
the overall levels of silent synapses are low in the nac ( i.e. < 10% ) , and juvenile animals exhibit higher levels ( e.g. 10% ) than adult animals ( e.g. ~3% ; huang et al . , 2009 ; lee et al . ,
regardless of the developmental regulation ( durand et al . , 1996 ) , 1 or 2 days after repeated intraperitoneal injections of cocaine
( huang et al . , 2009 ) or morphine ( graziane and dong , unpublished results ) , the levels of silent synapses in the nac are increased substantially ( to ~30% ) .
further results demonstrate that cocaine - induced generation of silent synapses involves synaptic insertion of new , glun2b - containing nmdars ( huang et al . ,
2009 ) and is accompanied by an increase in the density of dendritic spines ( robinson and kolb , 2004 ; brown et al . , 2011 ) , whereas morphine - induced generation of silent synapses involves internalization of ampars and is accompanied by a decrease in the density of dendritic spines ( robinson and kolb , 2004 ) .
thus , exposure to cocaine and morphine two abused drugs with distinct pharmacological effects but both causing addiction triggers opposing synaptic modifications and circuitry remodeling .
accompanying cocaine - induced generation of silent synapses and increases in spine density , several neuronal substrates that are important for synapse or circuitry formation during brain development are up - regulated in the nac , including synaptic glun2b - containing nmdars , transcription factor camp response element - binding protein ( creb ) , and neurotrophins ( dong and nestler , 2014 ) . based on these correlative results ,
cocaine - induced generation of silent synapses has been hypothesized as a synaptogenesis process involving transient reactivation of certain developmental mechanisms in the adult brain ( dong and nestler , 2014 ; huang et al . , 2015 ) . what developmental mechanisms may be reactivated after exposure to cocaine for the potential synaptogenesis process ?
first , cocaine - induced generation and the subsequent maturation of silent synapses is projection - specific ( lee et al . , 2013 ; ma et al . , 2014 ) , involving both postsynaptic construction and directed presynaptic growth .
thus , there should be trans - synaptic signaling that directs and coordinates pre- and postsynaptic approaching and connecting .
second , given the prominent effects of cocaine on dopamine release , the mechanisms are likely activated or regulated by dopamine signaling and are likely active preferentially in the mesolimbic dopamine systems .
one such candidate is the interaction between netrin1 and its presynaptic receptor deleted in colorectal cancer ( dcc ) . during circuitry development ,
dcc , located at the axon growth cone , directs axon growth toward a specific postsynaptic area where netrin1 is released ; disruption of dcc - netrin1 interactions disrupts synapse and circuitry formation ( barallobre et al . , 2005 ; round and stein , 2007 ) .
both netrin1 and dcc are highly enriched during early embryonic stages , when synapse and circuitry development is highly active .
after development , netrin1 and dcc are reduced to very low levels in most brain regions ( barallobre et al . , 2005 ; round and stein , 2007 ) , except in some midbrain sites ( osborne et al . , 2005 ) .
the netrin1-dcc - based synapse and circuitry development can be resumed following exposure to drugs of abuse .
it has been shown in a cell - based analysis that persistent activation of dopamine signaling , a major pharmacological consequence of cocaine exposure , quickly increases the level of dcc ( jassen et al . , 2006 ) .
furthermore , in a mouse line in which the expression of dcc is compromised ( dcc ) , reduced amphetamine - induced locomotor sensitization is observed ( flores et al . , 2005 ) .
these observations lead to a hypothesis that cocaine - induced generation of silent synapses may be initiated by dcc - netrin1-based pre- and postsynaptic approaching .
similar to cocaine , exposure to morphine also generates silent synapses in the nac ( graziane and dong , unpublished results ) .
however , in contrast to cocaine , morphine - induced generation of silent synapses in the nac is accompanied by a decrease in the density of dendritic spines , suggesting opposing underlying mechanisms ( graziane and dong , unpublished results ) . furthermore , a molecular manipulation that prevents ampar internalization prevents morphine - induced , but not cocaine - induced , generation of silent synapses in the nac ( graziane and dong , unpublished results ) .
these results lead to a hypothesis that morphine - induced generation of silent synapses is mediated by ampar internalization from preexisting synapses ( graziane and dong , unpublished results ) . this initial synaptic weakening process , if followed by a subsequent synapse elimination process , may result in a complete loss of affected synapses during morphine withdrawal .
these two opposing processes coordinate and cooperate with each other to establish and refine new neurocircuits during development .
as such , the potential morphine - induced synapse elimination process can also be triggered by a reactivation of certain developmental mechanisms .
the above analyses raise the possibility that exposure to cocaine and morphine triggers two opposing synaptic effects in the nac , namely synapse formation and elimination .
while this notion is intriguing , a legitimate question is whether these opposing synaptic effects produce similar circuitry consequences , given many similar behavioral consequences are induced after exposure to cocaine and morphine .
there are at least two levels at which drug - induced generation of silent synapses can remodel nac circuits . at the afferent level ,
as elaborated above , there are several excitatory projections to the nac , each presumably carrying out different aspects of addiction - related emotional and motivational information .
a critical question is whether drug - induced generation of silent synapses is a cross - board event , occurring in all projections , or a projection - specific occurrence .
thus far , we have examined the projections from the basolateral amygdala ( bla ) and medial prefrontal cortex ( mpfc ) after cocaine self - administration and observed similar generation of silent synapses in both projections ( lee et al . , 2013 ; ma et al . , 2014 ) .
however , the evolution of cocaine - generated silent synapses in these projections varies substantially .
for example , a portion of cocaine - generated silent synapses in the projections from the bla and infralimbic mpfc to the nac mature by recruiting glua2 subunit - lacking , calcium - permeable ampars ( cp - ampars ; lee et al .
compared to regular ampars , cp - ampars have a higher single channel conductance and , more importantly , can activate intracellular calcium - coupled signaling ; these properties may profoundly alter the synaptic properties within the affected circuits ( liu and zukin , 2007 ) . on the other hand , cocaine - generated silent synapses in the prelimbic mpfc to nac projection mature by recruiting regular , calcium - impermeable ampars ( ma et al . , 2014 ) .
these different maturation processes indicate that silent synapse - based circuitry remodeling not only quantitatively but also qualitatively changes the circuitry properties in the nac ( figure 1 ) . thus far ,
little is known about whether morphine - induced generation of silent synapses and potential subsequent maturation of these synapses exhibit such afferent specificity .
schematic diagram showing a hypothesized process of generation and evolution of silent synapses in cocaine - exposed animals .
it is hypothesized that exposure to cocaine triggers a synaptogenesis process by forming nascent , -amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor ( ampar)-silent excitatory synapses in the nucleus accumbens ( nac ; left ; dong and nestler , 2014 ) .
after withdrawal from cocaine self - administration , these silent synapses may : ( 1 ) mature by recruiting calcium - permeable ampars ( cp - ampars ) , ( 2 ) mature by recruiting noncp - ampars , or ( 3 ) be eliminated through metabolic turnover ( middle ) . generation and maturation of cocaine - generated silent synapses
contain both ampars and n - methyl - d - aspartate receptors ( nmdars ) and are indistinguishable via most electrophysiological measurements .
however , some of these matured silent synapses contain cp - ampars , and thus are susceptible to cp - ampar - oriented manipulations .
application of an in vivo long - term depression ( ltd ) protocol that preferentially targets synaptic cp - ampars to a specific nac afferent may selectively internalize cp - ampars from matured silent synapses within this afferent , pushing these synapses from the matured state ( containing both ampars and nmdars ) back to the immature state ( containing only stable nmdars ; right ) . at the efferent level
, the principal nac neurons can be roughly divided into two subpopulations , dopamine d1 receptor - expressing neurons and d2-expressing neurons , which preferentially project to the ventral tegmental area ( direct pathway ) and ventral pallidum ( indirect pathway ) , respectively ( smith et al . , 2013 ) .
thus far , all prior studies that examine drug - induced generation of silent synapses randomly sample nac neurons without distinguishing their subtypes .
it is tempting to speculate that exposure to cocaine and morphine preferentially generates silent synapses in d1-expressing and d2-expressing neurons , respectively . as discussed above , cocaine- and morphine - induced generation of silent synapses likely
involves two opposing cellular processes , one leading to synaptogenesis and the other leading to synapse elimination .
given the potentially opposing roles of nac d1- and d2-expressing neurons in drug - induced behaviors ( smith et al .
, 2013 ) , the two potentially opposing processes of silent synapse generation after exposure to cocaine and morphine may lead to the same shift in the balance of excitatory inputs between d1- and d2-expressing nac neurons , contributing to the same or similar behavioral outputs .
the behavioral consequences of drug - induced generation and the subsequent maturation of silent synapses start to be explored in a rodent relapse model called incubation of cue - induced cocaine craving . after drug self - administration , cue - induced drug seeking
becomes increasingly intensified over the withdrawal period , a phenomenon termed incubation of cue - induced drug craving ( grimm et al . , 2001 ) .
the incubated drug craving increases the likelihood of drug relapse during drug abstinence , and manipulating the incubation process may serve as an effective approach to reduce drug relapse . using in vivo optogenetic approaches
after long - term withdrawal from cocaine self - administration , matured silent synapses within specific nac afferents can be selectively reversed through in vivo long - term depression ( ltd ) procedures . to selectively target matured silent synapses in cocaine - exposed animals , the in vivo ltd procedure should meet at least three key standards .
first , to minimize nonspecific effects , the ltd procedure should not affect pre - existing synapses .
as such , the basal synaptic transmission ( e.g. transmission in saline - exposed animals ) should not be altered .
second , the ltd procedure should preferentially target cp - ampars , which are enriched in matured silent synapses .
third , the ltd procedure is likely projection - specific , as different projections often exhibit different synaptic properties .
bearing with these considerations , different ltd procedures are developed and verified , with which matured silent synapses within the bla - to - nac or pfc - to - nac projection can be re - silenced to their immature state as observed right after cocaine exposure ( lee et al .
reversing silent synapse maturation in the bla to nac shell projection reverses incubation of cue - induced cocaine craving , indicating the critical role of silent synapse - based remodeling of bla - to - nac projection in cocaine relapse ( lee et al . , 2013 ) .
similarly , reversing silent synapse maturation in the prelimbic pfc to nac core projection also reverses the incubated cocaine craving that has developed during drug withdrawal ( ma et al . , 2014 ) .
an interesting future direction would be to determine what mechanisms connect silent synapse - based circuitry remodeling in these two separate nac projections such that alterations in either projection is required for incubation of cocaine craving .
in contrast to the pro - relapse effects of the above two projections , reversing maturation of cocaine - generated silent synapses within the infralimbic mpfc to nac shell projection after long - term withdrawal from cocaine self - administration results in enhanced incubation of cocaine craving ( ma et al . , 2014 ) . thus , silent synapse - based remodeling of infralimbic mpfc to nac shell projection functions to counteract the development of cocaine incubation .
these results raise two important points : ( 1 ) for nac - based behavioral outputs , the function of glutamatergic synapses is highly pathway specific , and should be considered separately ; and ( 2 ) endogenous anti - relapse mechanisms exist and can be activated after exposure to drugs of abuse .
the efficacies of these anti - relapse mechanisms are masked by stronger pro - relapse mechanisms , but , if boosted up through appropriate manipulations , these anti - relapse mechanisms can be unleashed to reduce drug craving after drug abstinence .
this short review summarizes several critical questions provoked by recent findings of silent synapse - based circuitry remodeling . addressing these questions
will deepen our understanding about the cellular and molecular basis underlying drug - induced circuitry remodeling and may present circuitry - oriented therapeutic opportunities for treating drug addiction .
the author declares no conflict of interest related to the data presented in this manuscript .
Output:
| exposure to cocaine , and likely other drugs of abuse , generates -amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor - silent glutamatergic synapses in the nucleus accumbens . these immature synaptic contacts
evolve after drug withdrawal to redefine the neurocircuital properties .
these results raise at least three critical questions : ( 1 ) what are the molecular and cellular mechanisms that mediate drug - induced generation of silent synapses ; ( 2 ) how are neurocircuits remodeled upon generation and evolution of drug - generated silent synapses ; and ( 3 ) what behavioral consequences are produced by silent synapse - based circuitry remodeling ?
this short review analyzes related experimental results , and extends them to some speculations . |
PubmedSumm118608 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: physical activity , or rather the lack of it , has become a significant risk factor for chronic diseases in modern society .
the consequences of hypokinesis are widespread across highly developed ( 1 3 ) and developing countries ( those with average and low income ) ( 4 , 5 ) .
while confronting this phenomenon , public health campaigns around the globe put forward the increase of physical activity among inactive people as their primary goal ( 6 ) ( inactive meaning those who do not undertake vigorous or moderate physical activity , also known as sedentary society ) ( 7 ) . however , the sedentary lifestyle is not the exact opposite ofthe physically active lifestyle ( 2 , 8 , 9 ) .
although both the lack of physical activity and prolonged sitting are serious risk factors for chronic diseases , their consequences are not dependent on each other ( 3 , 1012 ) .
scientists have proven that the physiological effects of sedentary behaviours are often more harmful ( 13 ) than insufficient amounts of physical activity itself ( 14 , 15 ) .
it appears that activities requiring low energy expenditure such as sitting down , watching tv , reading , working in front of a computer , computer games , lying down or napping , or driving a car ( 1.01.5 met ) ( 16 , 17 ) may have a stronger relationship with the risk of metabolic syndrome than the lack of any physical activity at all ( 14 , 18 , 19 ) .
watching tv , in particular , is linked with obesity ( 20 , 21 ) , cardiovascular disease ( 22 , 23 ) or type ii diabetes ( 20 ) . on the other hand ,
the sedentary lifestyle is not necessarily asynonym for lack of physical acti - vity ( 24 ) , as shown by individuals who meet or exceed the recommended amount of physical activity , even though they spend a long time on sitting ( 16 ) . in this case
, the consequences of a prolonged sitting might be independent of the protective effects of regular physical activity .
there are individuals who do not meet the who recommendations , even though they do not spend a long time sitting . instead
regardless of the relationships described above , prolonged sitting is akey problem facing public health ( 13 ) .
it appears that adults employed on a full - time basis spend the majority of their working hours sitting ( 25 ) .
the rapid increase in the use of a car as the main means of transport leads to congestion on the roads and , in consequence , extends travel time ( especially during the peak hours ) ( 26 ) . spending leisure time on watching
first , it requires lower energy expenditure than any other sedentary behaviour ( for example , driving a car , writing or reading ) ( 28 , 29 ) .
scientists report that in a typical american household , the tv is switched on for longer than 8hrs per day ( 27 ) , with the average above 2hrs per day ( 25 )
. the sitting / lying down time median in other investigated countries is 5h per day ( from 3h per day in portugal , brazil and columbia , up to 6h per day in taiwan , norway , hong kong and saudi arabia ) ( 4 ) .
the above data indicate that attention should be turned towards understanding the mechanisms underpinning sedentary behaviours .
further exploration of these behaviours should change the direction of health research ( 7 , 30 ) .
qualitative and quantitative data collection is extremely important in this particular case , as it would contribute to our understanding of this constantly growing problem .
the aim of the current investigation was to evaluate the sedentary behaviours among the polish population , with a particular focus on the relationship between these behaviours and the possibility of compensating their effects with various forms of leisure - time physical activities .
the relationships between sitting time and individual factors of polish citizens ( age , gender , level of education ) and environmental factors ( the accessibility of the sports classes and venues , the ratings of these classes and the ratings of the local authorities work in the realm of sport and recreation ) are analysed in the current work .
the survey was conducted between 10 october 2012 and 14 november 2012via computer - assisted telephone interviews ( cati ) .
the interviews were administered by qualified and supervised surveyors who delivered the questions in a way that was equally easy to comprehend for all respondents .
the research tools in the current investigation were the polish long version of international physical activity questionnaire ( ipaq ) and the bespoke survey on the determinants of sport activity among the polish population .
the survey included questions about the frequency , duration , place and the type of sport for all activities .
additionally , the participants were asked to rate the attractiveness of these classes and to provide ratings of the work done by local authorities within sport and recreation .
the ipaq provided the information on physical activity in specific domains ( such as occupational , commuting , domestic chores , sports and leisure ) as well as the duration of sitting time during the weekdays and weekends ( 31 ) .
the respondents were asked about the duration of sitting at work , at home , while studying and in their leisure time in the last 7 days prior to the survey .
this included the time they spent sitting by the desk , sitting when visiting friends , while reading , watching tv or lying down ( sleep was not included ) .
the time of sitting in / on the vehicles ( i.e. , in a car , on a bus or on a motorcycle ) was also specified in minutes per day .
the total and average sitting times ( during the weekdays and weekends ) were calculated according to the formulae below .
total sitting time min / week = sitting time in minutes during weekdays x 5 days + sitting time in minutes during weekend x 2 days average sitting time min / day= sitting time in minutes during weekdays x 5 days + sitting time in minutes during weekend x 2 days / 7 the total weekly duration of sitting was obtained by adding the time spent on commuting / transportation per week . for the purpose of the current study , only information on physical activity undertaken in leisure time ( in the last week prior to the start of the survey ) was used . after performing a standardised calculation of the durations and the frequencies of declared physical activities ( vigorous , moderate activities and walking ) ( 31 ) , and with the who recommendations on the amount of physical activity needed to maintain a good health taken into account , the respondents were divided into two groups : those who follow the recommendations ( n=874 ) and those who do not ( n=630 ) .
furthermore , those who declared undertaking 150minutes of moderate physical activity or 75 minutes of vigorous physical activity per week ( or the equivalent combination of moderate and vigorous physical activity ) were classified as physically active .
the investigated sample consisted of 1,505 polish citizens ( age range 1864 years old ) .
they were selected through the stratified - quota sampling method , with the demographic variables such as age , gender , education and the place of residence as strata .
the quotas were established proportionally , based on the data that were made accessible to the researchers by the central statistical office .
furthermore , in order to increase the representativeness of the sample , a data - weighting procedure was usedfor the variables listed above .
the quotas were proportionally assessed based on the data provided by the central statistical office ( data sources : national census of population and local data bank ) .
the characteristics of the polish population statistical analysis was run on ibmspss statistics version 21 .
the descriptive statistical analysis provided detailed characteristics of the dependent variables by using the mean ( x ) , median ( me ) and standard deviation ( sd ) .
the kolmogorov - smirnov test was used for assessing whether the data are distributed normally ( the sitting time during the weekdays and weekends , the sitting time in the vehicles and the total sitting time were taken into account ) .
given that the assumption of normality in the collected data was violated ( p<0.05 ) , further statistical analyses required use of chi and non - parametric tests such as u mann - whitney , kruskall wallis and wil - coxon .
the significant differences between dependent and independent variables ( individual : age , gender , education , participation in sport for all ; environmental : the number of and the state of free and paid sports facilities , the costs and attractiveness of the classes offered by paid public sports and leisure centres , local authorities input in promoting physical activity ) were examined ( p<0.05 ) .
the relationships between the time spent on sitting and the individual and environmental factors among polish citizens were investigated through log - linear analysis .
the respondents were divided into two groups : those who spent more than 2545min per day on sitting and those who spent less than 2545min per day on sitting ( the median of the duration of sitting was the cutoff point ) .
there were two analyses run separately : one taking into consideration the individual factors and one for the environmental factors .
the strength of the relationship between these variables and the time polish citizens spend on sitting was expressed through the odds ratios ( or ) ( with 95% confidence intervals ) .
the descriptive statistical analysis provided detailed characteristics of the dependent variables by using the mean ( x ) , median ( me ) and standard deviation ( sd ) .
the kolmogorov - smirnov test was used for assessing whether the data are distributed normally ( the sitting time during the weekdays and weekends , the sitting time in the vehicles and the total sitting time were taken into account ) .
given that the assumption of normality in the collected data was violated ( p<0.05 ) , further statistical analyses required use of chi and non - parametric tests such as u mann - whitney , kruskall wallis and wil - coxon . the significant differences between dependent and independent variables ( individual : age , gender , education , participation in sport for all ; environmental : the number of and the state of free and paid sports facilities , the costs and attractiveness of the classes offered by paid public sports and leisure centres , local authorities input in promoting physical activity ) were examined ( p<0.05 ) .
the relationships between the time spent on sitting and the individual and environmental factors among polish citizens were investigated through log - linear analysis .
the respondents were divided into two groups : those who spent more than 2545min per day on sitting and those who spent less than 2545min per day on sitting ( the median of the duration of sitting was the cutoff point ) .
there were two analyses run separately : one taking into consideration the individual factors and one for the environmental factors .
the strength of the relationship between these variables and the time polish citizens spend on sitting was expressed through the odds ratios ( or ) ( with 95% confidence intervals ) .
the total sitting time of polish citizens ( during the weekdays , weekends and when commuting ) averages 9.45.1h / day ( 46.926.5h / week ) .
it appears that there is no difference in the average sitting time during weekdays and weekends ( 4.02.8h / day ; 242.9169.1h / weekend 4.02.7h / day ; 240.8162.9h / week , respectively ) .
the average time spent sitting in a vehicle was 78.4111.0min / day ( table 2 ) .
the significant relationships were not found when the socio - demographic factors were taken into account , with one exception : gender .
the results showed that men ( 251.1170 min / week ) spend significantly more time on sitting during weekends ( chi=45.0 ; p=0.04 ) than women ( 230.9155 min / week ) .
average ( sd ) sitting time ( in min / day ) and the total sitting time ( in min / week ) of the polish population during weekdays , weekends , spent in mechanical vehicles ( when commuting ) depending on the socio - demographic factors engaging in any type of physical activity of a continued duration of 10 minutes in leisure time was declared by 67.8% of the polish population ( table 3 ) .
it appears that participation in sport for all depends on gender ( chi=11.7 ; p<0.001 ) , age ( ch=58.7 ; p<0.001 ) and education ( ch=28.7 ; p<0.001 ) .
men ( 48.0% ) , young adults ( aged 1824 : 61.1% ; aged 2529 : 52.5% ) and those educated to a degree level ( 56.7% ) participated in sport for all more often than the remaining groups of respondents . women ( 60.8% ) , those in the 5059 and 6064 age groups ( 34.5% and 31.5% , respectively ) and respondents with primary education ( 64.1% ) more often declared lack of engagement in physical activities .
the most popular sports are cycling ( 21.2% ) , swimming ( 13.4% ) and running ( 12.2% ) .
cycling as a main type of physical activity is declared mostly by the respondents who are in the age range of 5059 ( 44.7% ) and over 60 years old ( 42.6% ) .
younger adults ( 1824 years old ) , on the other hand , choose swimming and running more of ten ( 26.9% and 35.2% , respectively ) .
overall , both men and women tend to choose cycling as their favourite type of sport ( 31.1% and 42.9% , respectively ) .
the frequency and duration time of sport activities in which polish citizens ( n=1,505 ) participated in their leisure time despite a relatively high proportion of respondents declaring participation in sport for all , only 9.6% of polish citizens exercise on a daily basis ( table 3 ) .
as many as 13.9% of the respondents engage in a physical activity 34 times per week and 24.3% exercise sporadically ( a few times per month or year ) .
the results show that more men than women exercised 12 times ( chi=7.3 ; p<0.05 ) and 3itimes ( chi=11.0 ; p<0.05 ) per week .
the proportion of men who did sports 1 2 times per week was 22.8% , whereas this proportion for women was 17.3% .
the same pattern was shown for the group of people declaring engaging in a physical activity 34 times per week ( 16.9% of men and 11.0% of women ) .
interestingly , women declared lack of any physical activity more often than men did ( 35.2% vs. 29.2% ; chi=6.2 ; p<0.05 ) .
furthermore , women who were physically active reported shorter durations of their exercises than men : they worked out for less than 30min / day more often than mendid ( 35.3% and 18.9% , respectively ; chi=69.1 ; p<0.05 ) . however ,
when the durations of more than 60min / day were considered , polish womenstrainings were less frequent than those of men ( 26.8% and 45.2% , respectively ; chi=42.4 ; p<0.05 ) .
it appears that women participated in organised classes more often than men did ( 34.3% , 16.2% , respectively ; chi=42.8 ; p<0.05 ) , whereas men reported using public sports facilities , free ( 19.5% and 19.8% ; chi=8.7 ; p<0.05 ) and paid ( chi=43.1 ; p<0.05 ) , more than women ( 12.5% and 6.1% ) . the proportion of people who met who health recommendations , based on the type of activity ( vigorous , moderate and walking ) undertaken in leisure time , was 58.1% ( in which the proportion of men was 57.7% and of women
despite the lack of significant differences when age , gender and education were taken into account , there was a relatively high proportion of physically active people in the 4049 age group ( 62.7% ) .
on the other hand , the analysis of individual and environmental factors showed that the only factor that determines the duration of sitting of more than 2545 min / week is participation in sport for all ( see table 4 ) , where the value of 2545min / week is a median of the total sitting time declared by the respondents . according to the results , the odds ratios of sitting above the median is higher ( or=1.33 [ 1.031.72 ] ) among those who do not engage in any form of physical activity in their leisure time ( 54.5%vs .
individual factors determining the sitting time , odds ratios ( or ) and the 95% confidence intervals of those sitting below and above 2545min / week the remaining factors , such as the accessibility of sports facilities , the attractiveness of the classes and facilities and the activities of the local authorities within the area of sport and recreation , do not play an important role in the longer durations of sitting ( see table 5 . ) .
it appears that the sitting time of the polish population is not dependent on the who health recommendations being met ( 58.1% ) or not ( 41.9% ) .
environmental factors determining the sitting time , odds ratios ( or ) and the 95% confidence intervals of those sitting below and above 2545min / week
the current investigation conducted on a representative sample of the polish population shows that the duration of sitting ( regardless of participation in any kind of physical activity ) is a very important risk factor for chronic diseases .
it appears that the time spent sitting has increased in comparison with the data from 2009 ( from 343min / day to 401.8min / day ) ( 32 ) . at the moment , polish citizens spend 2812.4159 - 3.9min / week sitting , which is very close to the numbers reported in the developed countries . for instance , british citizens sit 53.823.0h / week ( roughly 3228min / week ) , the dutch 60.021.0h-/week ( roughly 3602min / week ) and the americans from 53.019.8 to 56.023.5h / week , depending on the data sources ( roughly 3361 3860 min / week ) ( 33 ) .
the polish population s results are higher than those of countries such as czech republic ( 2295.5 min / week ) ( 34 ) , portugal ( 23071107 min / week ) ( 35 ) and belgium ( 21911057 min / week ) ( 35 ) .
the median sitting time of polish citizens is 2545 min / week , which is higher than in norway , where , depending on the level of education , men are more likely to spend their time sitting than women ( 3544h / week and 3240h / week , respectively ; these values in minutes per week would be 21002640 for men and
the spanish also spend less time sitting than polish people : 373.1184.6min / day ( roughly 2612min / week ) ( 37 ) .
however , it should be pointed out that the cited data were compared with the total time the polish population devoted to sitting ( during weekdays and weekends ) , including the time spent in vehicles when commuting ( the total without commuting time is 2418.81430.3 min / week ) , whereas the investigations conducted in the czech republic considered only the weekdays and the spanish research excluded the time spent sitting in mechanical vehicles ( when commuting ) .
furthermore , some of the authors ( 35 , 36 ) did not specify what was included in the sitting time .
additionally , it needs to be noted that in the research to date , there is a lack of sufficient evidence that the questions in the surveys were used appropriately ( the met thresholds have not been established ) .
this , in turn , suggests that the sitting - time indicator relies solely on the respondents declarations , which creates problems when comparing the data across different populations and does not seem to be a reliable measure of the total sitting time of any investigated population .
regardless of the methodological differences , it is clear that the duration of sitting among the polish population has increased and their physical activity level is insufficient ( only 9.6% of respondents exercise every day and 13.9% exercise 34 times per week ) .
thesenumbers are alarming and concerning , given that , according to some researchers , prolonged sitting significantly decreases the time people spend on exercising ( 39 ) . furthermore , as mentioned in the introduction , spending leisure time on sitting might decrease the possibility of meeting the who health recommendations ( 2 ) .
additionally , it may correlate with metabolic diseases ( 4043 ) , obesity ( 40 ) and high blood pressure ( 39 ) among those who are not physically active .
the current findings suggest that polish citizens who are not physically active are 1.33[1.031.72 ] times more exposed to sitting durations longer than 2545min / week ( > 6h ) .
it is worrying that within the investigated sample , the authors did not find a relationship between the sitting durations and their healthy behaviours ( implementation of the recommended amount of physical activity ) .
this suggests that polish citizens do not link the need to spend their leisure time actively with preventing asedentary lifestyle .
interestingly , they declare participation in sport for all ( 70% ) , but they do not see the need to exercise on a regular basis .
this may be a result of old habits or a lack of awareness of healthy lifestyle behaviours .
meanwhile , chu and moy ( 39 ) argue that even those who meet these recommendations but sit more than 9.3h per day are in the 3.82 times greater risk of developing metabolic syndrome .
it is therefore expected that this problem may also appear among the most active polish citizens ( those in the 4049 age group ) in the future . at the moment , the majority of the respondents in this particular age group ( 62.7% ) meet who recommendations , but their sitting time is longer than for those in other age groups ( 252.4173.5min / day ) . despite the fact that sedentary behaviours form an independent risk factor for modern diseases , it seems appropriate to ask whether the duration of sitting among the polish population is linked with the opportunities ( or the lack of thereof ) of undertaking leisure physical activity in their place of residence .
unfortunately , the database in the explored topic is rather limited and provides mostly information promoting healthy lifestyle choices ( 44 , 45 ) .
the majority of research focuses on the relationship between the undertaken physical activity and urbanisation ( 46 , 47 ) or pollution ( 48 ) ( particularly in the context of the means of transportation choice ) ( 49 ) .
the research to date also provides analysis of the relationship between environmental factors ( i.e. , access to the sports facilities ) and leisure physical activity ( 50 , 51 ) .
however , the data provided mainly concern the citizens of wealthy countries ( 5254 ) . in general , the health behaviours among people are the results of their individual characteristics ( such as income , age or education ) and the environmental factors ( such as the local authorities activities , sport and recreation infrastructure , physical activity initiatives , or the use of land ) ( 5557 ) . the results of the current study confirm that men ( 48.0% ) , young adults ( aged 1824 : 61.1%;aged 2529 : 52.5% ) and those educatedto a degree level ( 56.7% ) participate in the sport for all initiative more often than the remaining subjects .
these variables appear to be significant factors supporting the healthy behaviours of the respondents ( 58 , 59 ) .
however , many reports indicate that people are more likely to undertake a physical activity if they have the support of their social groups ( 60 ) and the governmental plans ( 61 ) .
the marketing strategies ( 62 ) , access to equipment ( 58 , 63 ) , financing public sport facilities ( 45 ) , promoting active ways of spending leisure time ( 64 ) , safety , andsupport of decision - makers on development and implementation of sport initiatives ( 65 ) strongly influence the development of attitudes and behaviours of those who live in environments that do not actively promote physical activity and present many barriers in accessing sport facilities .
this seems to be an issue for the people living in poor areas : they have to overcome more obstacles when making healthy choices ( 63 , 6668 ) .
this suggests that anincrease in accessibility of free sports facilities and better focus on the safety of public places may encourage those of poorer backgrounds to increase their physical activity ( 69 ) .
it appears that people are more active when they have access to sport facilities , both free and paid ( 70 ) . in rural missouri , for instance , making the hiking trails more accessible created an opportunity to promote physical activity among the groups of people who were at greatest risk of becoming physically inactive , especially among women and those with a lower socio - economic status ( 60 ) .
the closeness of golf courses has increased physical activity among older people ( 71 ) . however , providing free facilities does not itself lead to anincrease in physical activity , as shown in the current study ( 72 ) . despite the fact that 8.4% of the polish population take advantage of free sports facilities , there is no relationship between these activities and the time of sitting .
this yields the effective initiatives that would raise the awareness of the problem and the consequences of the sedentary lifestyle .
the plan for educating people about the ways to fight the sedentary behaviours is also needed .
unfortunately , the results of the current work suggest that a more intense campaign promoting a healthy lifestyle is needed in poland . as revealed by the analysis
, the environmental factors ( with the exclusion of one case of participation in the sport for all initiative ) did not correlate with the sitting time among the polish population .
the results showed that there was no relationship between the duration of sitting longer than 6hrs per day and the recommended by who amount of physical activity , the number and state of free and paid sports facilities , the cost and attractiveness of classes , and the engagement of local authorities in the area of sport and recreation .
this may indicate that local interventions are not effective , polish citizens prefer passive recreation and a lack of awareness in this matter .
it should be underlined that there is a link between lack of physical activity and the risk of prolonged sitting ( or=1.33[1.031.72 ] ) .
moreover , the recent natpol reports reveal that the level of physical activity among the polish population is ( at best ) moderate ( 73 ) .
additionally , the upcoming changes in the age structure within the population and a desperately low fitness level of polish youth may increase the proportion of inactive people .
with all the above in mind , the authors present the following conclusions :
the immediate cooperation with the ministry of health concerning the increase of polish citizens awareness of the risks brought by sedentary lifestyle is necessary.it is necessary to intensify the consistent efforts aiming at the development of the environments promoting anactive lifestyle among the polish population at their place of residence .
the focus of these efforts is also directed towards prevention of the sedentary lifestyle ; these efforts should include planning more effective strategies aiming to engage more local communities in active recreation , partnerships development and the exchange of experiences and information about the obstacles people have overcome.the suggestion that future recommendations forthe amount of physical activity include guidelines intervening in the time people spend on sitting seems well justified.further investigation of the environmental factors with the widest scope possible is advised .
the immediate cooperation with the ministry of health concerning the increase of polish citizens awareness of the risks brought by sedentary lifestyle is necessary .
it is necessary to intensify the consistent efforts aiming at the development of the environments promoting anactive lifestyle among the polish population at their place of residence .
the focus of these efforts is also directed towards prevention of the sedentary lifestyle ; these efforts should include planning more effective strategies aiming to engage more local communities in active recreation , partnerships development and the exchange of experiences and information about the obstacles people have overcome .
the suggestion that future recommendations forthe amount of physical activity include guidelines intervening in the time people spend on sitting seems well justified .
ethical issues ( including plagiarism , informed consent , misconduct , data fabrication and/or falsification , double publication and/or submission , redundancy , etc ) have been completely observed by the authors .
Output:
| abstractbackgroundthe aim of the current investigation was to evaluate the sedentary lifestyle of the polish population and its link with prolonged sitting in light of individual and environmental factors.methodsthe sample consisted of 1505 polish people between 18 and 64 years old .
the computer - assisted telephone interview ( cati ) survey was conducted with the polish version of international physical activity questionnaire ( ipaq - lf ) and the survey of the determinants of a sport activity among the polish population .
the relationships between the time spent sitting and the individual and environmental factors among polish citizens were investigated through log - linear analysis.resultsthe total time polish people spent sitting was 2812.41593.9 min / week . during the weekend , men ( chi2=45.0 ; p=0.04 ) spent significantly more time sitting than women ( 251.1170.1min / week , 230.9155.0 min / week , respectively ) . despite the relatively high proportion of people declaring participation in the sport for all initiative ( 67.8% ) ,
only 9.6% of polish people undertake a physical activity on a daily basis .
the odds ratios above the median ( > 2545 min / week ) are higher ( or=1.33 ; 95% ci=1.031.72 ) for those who are not physically active ( 54.5% vs. 45.5% ) .
there was no relationship between prolonged sitting time and the environmental factors.conclusionit is necessary to increase consistent efforts to create an environment that would successfully promote anactive lifestyle among polish citizens in their place of residence and prevent sedentary behaviours within this population .
the recommendations for physical activity should include the guidelines intervening in the time people spend sitting . |
PubmedSumm118609 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: the matter between stars , the interstellar medium , varies considerably from region to region in our galaxy .
the sun is inside a very large structure called the local bubble , a region of hot tenuous gas formed by supernova explosions tens of millions of years ago [ 13 ] .
adjacent to the local bubble is a similar but larger bubble , also formed from supernova explosions . inside the local bubble
are smaller , denser clouds which may have broken off from the bubble interaction region .
the h density of the local cloud is about 0.2 cm , the temperature is about 6000 k , and the cloud moves about 23 km / s with respect to the sun
. the magnetic field strength can not be directly measured , but based on models is 35 nt .
the sun is the source of the variable solar wind , with speeds measured near earth ranging from 250 to 2200 km / s , proton densities from 0.01 to > 100 cm , and an average magnetic field strength of 5 nt .
since the solar wind and local interstellar medium ( lism ) plasmas are both magnetized , they can not mix , so the lism flows around the heliosphere .
the boundary between the lism and solar wind is the heliopause ( hp ) , analogous to earth s magnetopause . since the solar wind is supersonic , a shock ( called the termination shock ) forms upstream of the hp . at the ts ,
the solar wind becomes subsonic and begins to turn toward the heliotail , the stretched - out downstream region analogous to earth s magnetotail .
if the lism were supersonic , a bow shock would form in the lism upstream of the hp , but recent data and analysis suggest that the lism flow is subsonic and thus the heliosphere does not have a bow shock .
voyagers 1 and 2 were launched in 1977 and are now exploring the interaction between the lism and the solar wind .
they both have crossed the ts and are in the region of shocked solar wind between the ts and the hp that is called the heliosheath . in late 2011 v1 was 119 au from the sun and v2 was 97 au , moving outward at 3.5 and 3.1 au / yr , respectively .
this paper reviews the observations made by these spacecraft as they enter unexplored regions of space .
the first observed influence of the lism on the solar wind was from the lism neutrals .
the neutrals are unaffected by the magnetic fields and flow into the heliosphere , where they are ionized in the solar wind and form hot , 1 kev , pickup ions .
these pickup ions dominate the thermal pressure outside about 30 au and play a major role in pressure balance structures outside this distance . accelerating the pickup ions to 1
kev slows the solar wind ; this slowdown was first observed near 30 au and by 80 au the solar wind had slowed by about 20% .
some of the energy from the pickup ions is transferred to the thermal protons , causing the temperature of the solar wind to increase with distance .
about 2.5 years before each ts crossing , the voyagers detected a new energetic particle component with proton energies of tens of kev to tens of mev flowing along the magnetic field lines .
this new particle component , called termination shock particles , signified that the voyagers were entering a region analogous to earth s foreshock , with particles accelerated at the ts streaming into the heliosphere along the magnetic field . for these particles to be observed , the ts distance had to be further at the flanks than at the nose so that magnetic field lines at the voyagers would also pass through the ts .
the bluntness alone could not account for all the particle observations ; an additional asymmetry in the heliospheric boundaries due to the interstellar magnetic field was also required .
the realization that the supersonic solar wind must go through a termination shock to become subsonic was first reported by parker .
the location of this shock is determined by the hp location and the upstream plasma parameters .
the hp forms where the solar wind dynamic pressure is balanced by the total lism pressure ; the value of the lism pressure is not well determined the distance to the ts , and thus the scale size of the heliosphere , were determined when v1 crossed the ts at 94 au in 2004 .
it crossed the ts in 2007 at 84 au [ 1720 ] , 10 au closer than v1 .
calculations of the ts motion based on changes in the solar wind dynamic pressure suggested that ts motion was responsible for only 23 au of the distance change .
thus the heliosphere is asymmetric , with the ts closer in the v2 than v1 directions .
models of the interaction of the heliosphere with the lism show that an asymmetry occurs if the lism magnetic field is tilted from the lism flow direction and has a magnitude of > 3 nt .
if these conditions held , the magnetic field would drape around the heliosphere so that the magnetic field strength builds up outside the southern part of the heliosphere , and the increased magnetic pressure would push the boundaries of the southern heliosphere inward .
the ts crossing provided other surprises as well . the ts was a weak shock , with a compression ratio close to two . at voyager 2 ,
the speed decrease started about 80 days before the ts crossing as the speed went from 400 to 300 km / s in three discrete steps .
the last step coincided with a sharp gradient in the energetic particle pressure , with the inward pressure gradient force large enough to produce the observed slowdown . at the v2 ts ( v1 does not have a working plasma instrument ) , the speed decreased from 300 to 150 km / s , the density and magnetic field increased by a factor of 2 , and the ion temperature increased by a factor of 30 . a major surprise ( but see zank et al . ) was that the heating of the thermal ions was much less than the decrease in the flow energy .
about 15% went to heating the energetic ( tens of kev ) ions , but the majority seems to have gone into heating the pickup ions , which are not directly observed .
the ts was the source of the low - energy particles observed in the foreshock ; the intensities of these particles peaked at the ts .
however , the anomalous cosmic ray ( acr ) intensities did not peak at the ts as expected , at least not where crossed by v1 and v2 .
acrs are singly ionized particle with 10100 mev / nuc ; they were observed first near earth and their origin was thought to be pickup ions formed from lism neutrals which were then accelerated at the ts .
the acr intensity did not increase at the ts ; no evidence an acr source at the ts was observed at either of the voyager crossing locations .
the heliosheath was thought to be , in analogy with planetary magnetosheaths , a highly turbulent region and this expectation has been correct [ 2325 ] . figs .
1 and 2 show the daily average plasma parameters obtained by fitting the observed spectra to convected , isotropic proton distributions .
the broad envelope of the data and the 25-day running averages that are superposed show consistent trends . however , the individual sets of spectra very greatly on time scales of tens of minutes .
the magnetic field also varies by factors of 23 over similar time scales , confirming the very dynamic and turbulent nature of this region .
as v2 moves deeper into the heliosheath , these fluctuations decrease slowly in magnitude but remain significant . by the end of 2011 , v2 was 14 au past the ts crossing distance of 84 au .
models suggest that the ts has moved inward 8 au since the ts crossing due the very low solar wind dynamic pressure during the recent solar minimum .
the expectation was that the plasma speed would decrease across the heliosphere and the flow direction would turn tailward .
1 shows that , contrary to these expectations , the average speed at v2 has remained roughly constant at 150 km / s for over 4 years , with a brief dip in speed at 2009.7 followed by a recovery in 2010.5 .
these observations of steady speeds are not predicted by models and are not understood .
although the speed is not slowing , the direction of the flow at v2 is turning as expected .
1 shows that the flow in the rt plane ( the rtn coordinate system has r radially outward , t parallel to the solar equatorial plane and positive in the direction of solar rotation , and n completes a right - handed system ) is about 20 after the ts crossing and increases to about 45 at the end of 2011 .
the flow in the rn plane was toward the south as expected , starting at about 10 after the ts , then oscillating for about a year before it started a monotonic increase to 25 at the end of 2011 .
the initial deflections at the ts must be due to the ts being at an angle to the radial flow . as discussed above
, the ts is blunt near the nose , less curved than a circle , so the flow at the ts is deflected away from the nose of the heliosphere . as the plasma moves across the heliosheath it continues to turn away from the nose , as expected .
the rt angle plot shows a cutoff at about 50. this cutoff is an instrumental effect ; when the flow direction is at too large an angle to the instrument look direction the plasma is not detected . in this case
the distributions of the plasma properties in the heliosheath are well represented by gaussian distributions .
the observed distributions of the plasma parameters are fit to gaussians to find the average properties and standard deviations . for the rt angle , which is cut off at about 50
, we can fit the distribution below 50 with a gaussian and determine the average flow angle .
the flow angles determined from these fits are shown by the dashed line in fig .
1 , which shows the flow is 56 from radial in the t direction in 2011 .
note that the rt angles ( and thus speed ) are greater than the rn angles throughout the heliosheath .
more of the plasma goes around the sides than over the top of the heliosheath , at least in the southern hemisphere where v2 is located , which suggests that the heliosheath is compressed at the southern pole .
2 shows the radial speed vr , the density n and the temperature t in the heliosheath .
although the speed has remained roughly constant as shown above , vr decreased from 130 to 100 km / s as the flow turned tailward . after the ts , the density initially averaged about twice the 0.001 cm value in the solar wind but had large , factor of 34 , fluctuations . by the end of 2008
the cause of the density decrease is likely partially the reduced solar wind flux coming from the sun in the recent solar minimum and partially a heliolatitude effect . at solar
minimum the solar wind flux decreases with heliolatitude , so v2 at 30 s should observe less flux than observed near earth at low - latitudes .
however , a problem with this hypothesis is that these lower fluxes are associated with higher flow speeds , which are not observed in the heliosheath .
the decrease in fluctuations may result from the very quiet solar wind conditions in this solar minimum combined with v2 moving further from the ts .
the density increased by a factor of two during a 6 month period in 2011 , perhaps because of a diminishment of the heliolatitudinal flux gradient as solar minimum ends .
the average density at the end of 2011 is similar to that observed just after the ts crossing , but the fluctuations in daily averages are much smaller .
the temperature decreased from 150,000 k after the ts to about 40,000 k in 2011 .
perhaps it reflects cooler solar wind encountering the ts or less heating at the ts due to differences in the upstream flow parameters .
the temperature increased slightly in 2011 in concert with the increase in density , but the reason is unclear .
although the plasma instrument on v1 does not work , the speeds in the r and t direction can be calculated from the low energy charged particle ( lecp ) instrument observations of tens of kev ion intensities using the compton - getting effect .
the speed after the ts was below 100 km / sand monotonically decreased from 70 km / s in mid-2007 to 0 km / s in early 2011 and has since become negative .
the t component of the speed averaged 40 km / s until mid-2010 , when it started to decrease .
. suggest that the decrease of the speed to near zero signifies that v1 has entered a boundary region in front of the hp in which flow is parallel to the hp .
the v1 spacecraft was recently reprogrammed to do roll maneuvers so that vn could also be determined , and vn is also small < 20 km / s .
thus the v1 has entered a region with nearly stagnant flow which was not predicted .
models show that such a region could be part of the global spatial character of the heliosphere or a time dependent feature near the boundary of the fast and slow solar wind regimes near solar minimum .
since the observed speeds are very low , comparable to the 23 km / s expected in the lism , one might wonder if v1 has already crossed the hp . the magnetic field increased by about a factor of 2 in the stagnation region but that the direction has not changed .
the field is still consistent with the parker spiral direction ; this direction is expected to change in the lism , so v1 likely has not crossed the hp .
the increase in magnetic field magnitude is consistent with predictions that the field will be compressed as it pushes up against the hp boundary .
the most probably explanation for these data is that v1 has entered a boundary layer near the hp but has not yet crossed the hp .
the acr intensity has increased slowly as the voyager spacecraft move deeper into the heliosheath . at v1 ,
the spectra are almost power laws , indicating that v1 is near the source region .
one is that they are accelerated on the flanks of the heliosphere where the particles can interact with the ts longer , then move along the magnetic field lines to the voyager spacecraft .
another hypothesis is that acrs are accelerated by second order fermi acceleration by magnetic islands or ridges near the hp .
a third is that reconnection occurs as the current sheets are compressed near the hp , leading to particle acceleration .
the voyagers may be able to differentiate between these possibilities as they approach and cross the hp .
the voyager spacecraft celebrate their 35th year in space in august 2012 and continue exploring new regions of space .
they should continue to return data until 2025 , when we expect they will be well into the interstellar medium .
this paper describes some of the new discoveries and new mysteries resulting from recent observations .
some of the more intriguing puzzles are the source of the acrs , the very different speed profiles observed in the v1 and v2 directions , and the formation of a boundary layer in front of the hp .
Output:
| this paper provides a brief review and update on the voyager observations of the interaction of the heliosphere with the interstellar medium .
voyager has found many surprises : ( 1 ) a new energetic particle component which is accelerated at the termination shock ( ts ) and leaks into the outer heliosphere forming a foreshock region ; ( 2 ) a termination shock which is modulated by energetic particles and which transfers most of the solar wind flow energy to the pickup ions ( not the thermal ions ) ; ( 3 ) the heliosphere is asymmetric ; ( 4 ) the ts does not accelerate anomalous cosmic rays at the voyager locations ; and ( 5 ) the plasma flow in the voyagers 1 ( v1 ) and 2 ( v2 ) directions are very different . at v1
the flow was small after the ts and has recently slowed to near zero , whereas at v2 the speed has remained constant while the flow direction has turned tailward .
v1 may have entered an extended boundary region in front of the heliopause ( hp ) in 2010 in which the plasma flow speeds are near zero . |
PubmedSumm118610 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: patients within this group are at risk of energy imbalance and an increased prevalence of obesity
. studies of childhood cancer survivors who were treated in the 1970s and 1980s demonstrate a clear association between cranial radiotherapy ( crt ) and an increased prevalence of obesity , especially with higher radiation doses [ 24 ] .
contemporary treatment protocols have removed crt for the majority of children with all and , where it is still utilized , reduced the doses delivered . despite these improvements in treatment protocols , obesity is still a concern during treatment and follow - up [ 58 ] .
various risk factors have been identified including younger age at diagnosis [ 5 , 7 ] , elevated body mass index ( bmi ) at diagnosis , dose of corticosteroid , treatment risk [ 9 , 10 ] , and female sex [ 8 , 11 ] but these observations are not consistent among all reports [ 9 , 10 ] . in a recent meta - analysis of obesity in survivors of pediatric all , zhang et al . concluded that such modifiers of bmi remain speculative .
for those studies of patients on modern treatment protocols for all with multiple observations during treatment , few have adjusted for or included all these predictors in the same analysis .
our aim was to identify those patients at greatest risk of becoming obese during treatment for all .
we therefore performed a retrospective chart review of all children and adolescents diagnosed with all in western australia between 2003 and 2007 to evaluate longitudinal changes in bmi during treatment for all and to identify risk factors that would inform future intervention strategies .
between 1 january 2003 and 31 december 2007 , a total of 89 children ( 017 y ) were newly diagnosed with all in western australia . all patients were treated at princess margaret hospital ( pmh ) for children , the sole tertiary pediatric hospital in the state of western australia .
patients were treated on a variety of children 's cancer group ( ccg ) or children 's oncology group ( cog ) protocols .
exclusion criteria included patients with infant all ( n = 3 ) , mature b cell all ( n = 2 ) , and trisomy 21 ( n = 2 ) and patients who did not proceed to maintenance therapy due to relapse ( n = 1 ) or death ( n = 1 ) .
thus , 80 patients were eligible for inclusion in this study ( see figure 1 ) .
medical records were retrospectively reviewed and information pertaining to auxology and cancer treatment was abstracted .
data collected included height ( meters ) and weight ( kilograms ) ; risk stratification , which correlates with therapeutic intensity , according to national cancer institute ( nci ) criteria ( standard / high ) ; cumulative corticosteroid exposure ; and receipt of crt .
heights ( measured using a stadiometer ) and weights were obtained at the start of each treatment phase by accredited oncology nurses for the purpose of calculating chemotherapy doses , where available heights and weights from other oncology visits were included . during treatment , height and weight were collected at least every three months .
cumulative steroid doses during treatment were calculated in mg / m for both dexamethasone ( dex ) and prednisone ( pdn ) .
the total cumulative steroid dose was expressed as pdn equivalents after multiplying the dex dose by 6.67 to account for the differences in steroid potency .
for the analysis , total steroid dose was cumulated separately for the duration of maintenance treatment and for the early treatment period prior to maintenance .
heights and weights were therefore collected for 3.35 years after the start of treatment for all patients unless data were censored at the date of relapse , transferring out of western australia , or transition to adult services ; see figure 1 for summary .
this audit was approved by the child and adolescent health service , quality and safety committee with delegated authority from the pmh institutional review board .
it conforms to the provisions of the declaration of helsinki in 1995 ( as revised in tokyo 2004 ) and the national statement on ethical conduct in human research , australian national health and medical research council .
heights and weights of children from the raine study were used as a comparison population to the all cohort . the raine study ( http://www.rainestudy.org.au/ )
briefly , 2900 pregnancies were recruited at king edward memorial hospital ( perth , western australia ) at 18 weeks ' gestation from 1989 to 1991 .
auxological review of this pregnancy cohort was carried out at ages 1 , 2 , 3 , 6 , 8 , 10 , 14 , 17 , and 21 years .
the current raine cohort has been shown to be representative of the ethnicity and demographics of the general population of perth , western australia .
this study was approved by the raine executive committee and the ethics committees of king edward memorial hospital and pmh .
written consent was provided by adolescent participants and their accompanying parent or guardian . in comparison with the raine cohort ,
33% of the patient cohort were born at the same time of within 5 years of the raine cohort , 35% of the patient cohort were born within 510 years of the raine cohort , and 32% were born within 1015 years of the raine cohort .
the outcome of interest was bmi , which was calculated using the standard formula : weight ( kg)/height ( m ) .
bmi values for patients aged between 2 and 20 years were converted to age and sex - adjusted z - scores using the formula ( ( ( x / m ) ) 1)/ls , where x is the bmi measurement and l , m , and s are the age and sex specific values for the power in the box - cox transformation and the median and the coefficient of variation , respectively , by the sas macros for the center for disease control ( cdc ) 2000 growth charts [ 15 , 16 ] .
bmi z - score categories are defined as underweight ( < 5th percentile ) , healthy weight ( 5th percentile to < 85th percentile ) , overweight ( 85th to < 95th percentile ) , and obese ( 95th percentile ) .
who 2006 growth charts were used to calculate the bmi z - score at diagnosis for the six children who were less than two years of age .
these values were not included in the longitudinal response variable but were included in a covariate variable ( bmi z - score at start of treatment ) to ensure that all individuals were included in the statistical analysis .
proportions were compared using fisher 's exact test ( independent samples ) or mcnemar 's test ( paired data ) .
longitudinal bmi z - scores for the all cohort were analyzed using linear mixed - effects , including fixed effects for time since start of treatment ( quartic polynomial ) and time - dependent interactions with sex , age , and bmi z - score at the start of treatment , nci risk , and total maintenance steroid dose received .
random effects for intercept and time and a compound symmetry correlation structure for the errors using the lme function from the statistical package nlme in r were included in the models [ 17 , 18 ] .
p values were calculated for each covariate , including associated interaction terms , using the likelihood ratio test .
sample - mean predicted bmi z - scores were estimated using the pred function ( package nlme ) and associated 95% confidence intervals were calculated , which were graphed using the ggplot2 package .
longitudinal bmi z - scores for the raine cohort were analyzed similarly , including fixed effects for age ( quartic polynomial ) and age - dependent sex interaction and random effects for intercept and age . a significance level of 5%
selected characteristics of the 51 male and 29 female patients included in the study are presented in table 1 .
the median age at diagnosis was 5.49 years ( range : 1.0216.66 ) , with six children diagnosed before 2 years of age .
the majority of the children were diagnosed with pre - b all ( 88.8% ) , of which 73% ( n = 52/71 ) were standard risk .
patients were treated on ccg and cog protocols : ccg1961 ( n = 10 ) , ccg1991 ( n = 24 ) , all0031 ( n = 4 ) , all0232 ( n = 12 ) , all0331 ( n = 29 ) , and all0434 ( n = 1 ) .
the duration of treatment was greater for males ( median 3.18 years ) than females ( median 2.18 years ) , as males receive an additional year of maintenance therapy on these protocols .
twelve patients ( 15% ) ( 10 male , 2 female ) received crt as part of their therapy .
the majority of patients received dex ( n = 62 , 78% ) as the only corticosteroid , one patient received pdn only , and the remaining 17 patients received both dex and pdn during treatment .
no patient received growth hormone during treatment or in the two years immediately following the end of therapy . at the time of diagnosis the bmi z - scores for individuals with all predominantly fall within the 95% prediction interval for the healthy ( raine ) cohort ( figure 2(a ) ) ; 77.5% ( 62/80 ) of the patients were in the healthy weight category , 3.8% ( 3/80 ) were in the underweight category , and 8.8% ( 7/80 ) were classified as overweight and 10% ( 8/80 ) as obese according to cdc reference standards .
there was no sex difference in the proportion of males and females in each of the bmi categories . at the end of treatment ( figure 2(b ) ) , 46.3% ( 37/80 ) of the patients were in the healthy weight category , 2.5% ( 2/80 ) were in the underweight category , 26.3% ( 21/80 ) were classified as overweight , and 25% ( 20/80 ) were classified as obese . at the end of treatment
, there was an increase in bmi z - scores for individuals with all diagnosed before 10 years of age , whereas individuals diagnosed after 10 years of age predominantly were within or below the 95% prediction interval for the healthy ( raine ) cohort . by the end of treatment
there were significant differences in the proportions of males and females in each bmi category ( p = 0.006 ; fisher 's exact test ) . during treatment ,
increases in bmi z - scores were greater for females than males ; the prevalence of obesity increased from 10.3% to 44.8% ( p < 0.004 ) for females but remained relatively unchanged for males ( 9.8% to 13.7% , p = 0.7 ) .
the mean number of bmi observations per individual was 34.8 ( sd 19.7 ) for females and 27.9 ( sd 17.0 ) for males .
the peak increase in bmi z - scores occurs around two years posttreatment , for both sexes , and thereafter gradually declines ( figure 3 ) .
the acceleration in bmi z - scores in females , compared to males , predominantly occurs between 6 and 12 months posttreatment , whereas from two years posttreatment an approximately constant mean difference in bmi z - scores is maintained between the sexes .
bmi z - scores were associated with sex , nci risk , age and bmi z - score at diagnosis , and total maintenance therapy steroid dose ( see table s1 in supplementary material available online at http://dx.doi.org/10.1155/2015/386413 ) .
no associations were detected between bmi z - scores and either total steroid dose in premaintenance therapy or cranial radiotherapy .
significant associations with bmi z - scores were identified for time - dependent interactions with sex ( lrt p = 0.0005 ) , bmi z - score at diagnosis ( p = 0.0005 ) , and total dose of steroid during the maintenance phase ( p = 0.004 ) , in addition to sex and time interactions for nci risk ( lrt p < 0.0001 ) and age at diagnosis ( lrt p = 0.0001 ) .
these interactions are illustrated in figure 4 and contrasted with mean bmi z - score for healthy ( raine ) males and females at the same age .
standard risk and earlier age at diagnosis were associated with the greatest increases in mean bmi z - score , which is more pronounced in females .
bmi z - scores for high - risk individuals were not significantly different from healthy individuals for either sex
. table 2 illustrates that , on average , standard risk females have bmi z - scores 1 sd higher than healthy females of the same age .
a similar effect size was seen in standard risk males for the youngest age group ( 2 years ) but this effect rapidly diminished across the older age groups . to further investigate the relationship between bmi z - score and steroid intake we predicted bmi trajectories based on identical steroid doses ( total maintenance therapy ) in males and females using the fully adjusted model described above ( figure s1 in supplementary material ) .
although slightly higher mean bmi z - score values are predicted with higher steroid doses , the greatest increases are based on female sex and earlier ages at diagnosis .
obesity is a recognized consequence of treatment for all ; however , risk factors for this increase remain speculative .
obesity may exacerbate late - effects of cancer therapy such as cardiovascular and metabolic health ; it is therefore important to identify survivors of all who are at greatest risk of becoming obese .
our longitudinal analysis which includes a median of 30 auxological measurements per patient over a period of 3.35 years has confirmed that bmi increases during treatment for all in childhood .
the prevalence of obesity in the western australian all cohort increased from 10% at the start of treatment to 25% by the end of treatment for the whole cohort , similar to other reports of 11% to 21% and 14% to 23% , where increases in mean bmi were expressed as z - scores based on the cdc reference population and increases of 0.61.0 sd units [ 6 , 7 , 10 ] are similar to our observed increase of 0.6 sd units from the start to the end of treatment . while there was a significant increase in mean bmi z - score during maintenance treatment in the study by esbenshade and colleagues , the prevalence of obesity at the start and end of treatment ( 19% versus 21% ) was not significantly different , which may be explained by a higher prevalence of obesity at diagnosis in this study compared with other studies . in our cohort ,
female sex was a risk factor for increased bmi during treatment for all . in the longitudinal mixed - effects model adjusted for sex only , there were differences in predicted mean bmi z - scores between males and females .
although mean bmi z - scores increased during the first two years of treatment for both sexes , this increase was greater for females than males .
consistent with our observation , greater increases in bmi during treatment for females compared to males have been identified during treatment in several studies [ 5 , 6 , 8 , 20 ] , whereas other studies have found no differences between the sexes [ 9 , 10 , 21 ] .
analysis of adult bmi in one of the largest cohorts of childhood cancer survivors , the childhood cancer survivor study , has confirmed that there is a greater prevalence of obesity in adult female survivors of all compared to males .
in addition , a uk cohort treated from 1997 to 2003 , which excluded patients who received crt , also found increased bmi z - scores in females , which persisted 6 years after end of treatment .
taken together , these data raise the possibility that increases in bmi during treatment for all in childhood persist into adulthood .
longitudinal changes in bmi z - scores in children treated for all were associated not only with sex but also with age at diagnosis and nci risk / therapeutic intensity . for
patients with high - risk all , mean bmi z - scores did not increase with treatment irrespective of age at diagnosis or sex . for patients with standard risk all ,
mean bmi z - scores increased for standard risk females irrespective of age but only younger standard risk males had an increase in bmi z - score .
thus , for standard risk patients predictors for increased bmi during treatment are younger age at diagnosis and being female .
studies typically investigate the association of bmi with either age at diagnosis or risk profile due to the potential confounding effects of age at diagnosis , which is one of the determinants of disease risk .
younger age at diagnosis has been associated with increased bmi in several studies [ 7 , 8 , 23 ] .
in addition , an association between treatment for higher risk all and lower bmi during treatment has also been reported [ 9 , 10 ] .
although they are administered in high doses during treatment for all , few studies provide data on corticosteroid exposure during treatment for all , of which some [ 23 , 25 ] support a role for corticosteroids in the development of obesity whereas others do not [ 3 , 9 , 26 ]
. a recent meta - analysis did not include corticosteroid exposure in its analysis due to the small number of studies with the availability of this data . in our cohort
we identified a small , albeit significant , effect of cumulative steroid dose during maintenance and bmi .
there was no interaction between corticosteroid dose and sex and therefore this association does not explain why females who are treated with one year less maintenance therapy compared with males have a higher prevalence of obesity by the end of treatment .
corticosteroids are widely used for other pediatric illnesses and while their use is associated with side effects such as adrenal suppression and altered bone metabolism [ 2729 ] there are no reports of increased prevalence of obesity in females compared to males due to corticosteroid exposure .
it is known that cancer survivors who were treated in the 1970s and 1980s are at increased risk of becoming obese with risk persisting well into adulthood .
children treated for all or brain tumors with high doses of crt are most at risk , especially females or those who were younger at diagnosis [ 30 , 31 ] . increased
risk of obesity has been associated with crt doses 20 gy or 18 gy .
various studies have suggested that crt is associated with hypothalamic damage which leads to hyperleptinemia and/or gh deficiency in young adulthood [ 3235 ] .
however , analysis of cohorts treated since 1990 that include patients exposed to crt does not show an association with crt and increased bmi [ 5 , 8 , 9 ] .
cranial radiation was not identified as a risk factor for increased bmi in our cohort .
however , the 15% of the patients that received crt were administered a relatively low ( 1218 gy ) dose compared to earlier studies where over half of the study cohorts received much higher doses of crt .
further studies are required to elucidate the etiology of obesity in children treated for all on contemporary protocols , in particular why females are more susceptible to the late - effects of treatment compared with males , an effect that is consistent among a variety of cancer diagnoses and treatment protocols .
the ccg / cog treatment protocols for all typically include one year less maintenance therapy for females compared with males , yet paradoxically they are at an increased risk of obesity , suggesting that treatment regimes per se may not explain the sex difference and that further studies should focus on life style factors in addition to treatment modalities .
younger age at diagnosis is consistently a risk factor for development of endocrine late - effects of treatment in cancer survivors including obesity .
one study has reported that children diagnosed with all who were younger than 2.5 years of age were more likely to experience an earlier adiposity rebound which is an important risk factor in adult obesity .
long - term survivors of all are at risk of elevated abdominal obesity , an atherogenic ldl phenotype , and diabetes .
additional follow - up of recent cohorts of all survivors beyond the end of treatment and into adulthood may determine incidence of metabolic syndrome and other morbidities .
recent studies that focus on energy balance through eating behavior and physical activity in all survivors suggest obesity in survivors is a result of both disordered / increased energy intake and reduced physical activity associated with fatigue , with the decrease in physical activity greater for females compared to males [ 42 , 43 ] .
the strengths of our study include the frequent measurement of heights and weights and analysis by longitudinal modelling .
thus , female patients in our cohort who received standard risk protocols for all as well as younger males who received standard risk protocols for all were at the greatest risk of becoming obese towards the end of treatment .
our patient cohort was compared to the raine cohort which is from the same geographical location .
all children and adolescents diagnosed with all in the state of western australia are treated at pmh and therefore our cohort has 100% ascertainment of the selection criteria for the state .
we have compared the changes in bmi of our all cohort to both the cdc reference population and the raine cohort which is representative of the western australian population .
although the mean bmi z - scores were slightly greater in the raine population compared to the cdc reference , the increases in the bmi z - scores of the cohort with all were greater than those observed for children in the raine cohort over the same time frame .
a third of our patient cohort was born 1015 years after the raine . however , a meta - analysis of trends in the prevalence of childhood overweight and obesity in australia between 1985 and 2008 identified an increase in mean bmi z - score of no more than 0.1 sd units in any 3-year period with no significant differences in the rates of change between boys and girls .
it seems unlikely therefore that the increases in bmi observed in our patient cohort reflect secular changes in our local population . in conclusion
, this study has confirmed that there is an increased prevalence of obesity at the end of treatment for childhood all . in the statewide cohort of western australian children
treated on ccg / cog protocols between 2003 and 2007 , the biological risk factors for increased bmi / obesity during standard risk therapy are younger age at diagnosis and female sex .
the philosophy of nutritional / dietician support in oncology units concentrates on detecting underweight children and adding high calorie feeds .
while further data is required to determine the causes of obesity in survivors and the female propensity , our findings support further consideration of appropriate nutrition and energy balance during therapy and empowering of parents to exert control over excess calorie intake in their children with leukemia in the same manner as for their healthy children .
Output:
| objective & design .
we undertook a retrospective review of children diagnosed with acute lymphoblastic leukemia ( all ) and treated with modern cog protocols ( n = 80 ) to determine longitudinal changes in body mass index ( bmi ) and the prevalence of obesity compared with a healthy reference population .
results . at diagnosis ,
the majority of patients ( 77.5% ) were in the healthy weight category . during treatment ,
increases in bmi z - scores were greater for females than males ; the prevalence of obesity increased from 10.3% to 44.8% ( p < 0.004 ) for females but remained relatively unchanged for males ( 9.8% to 13.7% , p = 0.7 ) .
longitudinal analysis using linear mixed - effects identified associations between bmi z - scores and time - dependent interactions with sex ( p = 0.0005 ) , disease risk ( p < 0.0001 ) , age ( p = 0.0001 ) , and bmi z - score ( p
< 0.0001 ) at diagnosis and total dose of steroid during maintenance ( p = 0.01 ) . predicted mean bmi z - scores at the end of therapy were greater for females with standard risk all irrespective of age at diagnosis and for males younger than 4 years of age at diagnosis with standard risk all .
conclusion .
females treated on standard risk protocols and younger males may be at greatest risk of becoming obese during treatment for all .
these subgroups may benefit from intervention strategies to manage bmi during treatment for all . |
PubmedSumm118611 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: informed consent was provided by families of medulloblastoma patients treated at children s hospital boston , the hospital for sick children toronto and institutions contributing to the children s oncology group / cooperative human tissue network , under approval and oversight by their respective internal review boards .
all tumors were obtained at the initial surgical resection and recurrent tumors were excluded from our analysis .
hematoxylin and eosin stained slides of tumor samples were pathologist reviewed to confirm the diagnosis of medulloblastoma , determine histological subtype when able , and assess tumor purity .
exome sequencing of dna from 92 tumor / normal pairs was performed using in - solution hybrid - capture of 193,094 exons from 18,863 mirna- and protein - coding genes , followed by sequencing of 76 bp paired - end reads using illumina sequencing - by - synthesis technology .
the ~33 mb target region was sequenced to 106x mean coverage in each sample ( range 73 234 ) .
gene expression data and copy number profiles ( derived from snp microarrays or sequence data ) were used to assign each tumor to a subgroup using published criteria .
our cohort consisted of 6 wnt(c6 ) , 23 shh(c3 ) , 33 group 3(12 c1 , 21 c5 ) , and 30 group 4(12 c2 , 18 c4 ) tumors ( see supplemental table 1 for case annotations ) .
mutations were detected using mutect , annotated using oncotator , and manually reviewed using the integrated genomics viewer ( igv ) . for validation , pcr on access array microfluidic chips ( fluidigm ) was followed by single - molecule real - time sequencing ( pacific biosciences ) per manufacturer s instructions .
subreads were extracted and assigned to samples using manufacturer s and custom software , and aligned to the hg19 ( grch37 ) build of the human reference genome sequence using bwa - sw .
Output:
| medulloblastomas are the most common malignant brain tumors in children1 .
identifying and understanding the genetic events that drive these tumors is critical for the development of more effective diagnostic , prognostic and therapeutic strategies .
recently , our group and others described distinct molecular subtypes of medulloblastoma based on transcriptional and copy number profiles25 . here , we utilized whole exome hybrid capture and deep sequencing to identify somatic mutations across the coding regions of 92 primary medulloblastoma / normal pairs .
overall , medulloblastomas exhibit low mutation rates consistent with other pediatric tumors , with a median of 0.35 non - silent mutations per megabase .
we identified twelve genes mutated at statistically significant frequencies , including previously known mutated genes in medulloblastoma such as ctnnb1 , ptch1 , mll2 , smarca4 and tp53 .
recurrent somatic mutations were identified in an rna helicase gene , ddx3x , often concurrent with ctnnb1 mutations , and in the nuclear co - repressor ( n - cor ) complex genes gps2 , bcor , and ldb1 , novel findings in medulloblastoma .
we show that mutant ddx3x potentiates transactivation of a tcf promoter and enhances cell viability in combination with mutant but not wild type beta - catenin .
together , our study reveals the alteration of wnt , hedgehog , histone methyltransferase and now n - cor pathways across medulloblastomas and within specific subtypes of this disease , and nominates the rna helicase ddx3x as a component of pathogenic beta - catenin signaling in medulloblastoma . |
PubmedSumm118612 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: this study was designed to assess adherence to national guidelines for the immunization of people with diabetes and to evaluate predictors of vaccination .
this was a cross - sectional analysis of data extracted from the electronic medical record ( emr ) system at kent hospital , a 359-bed public teaching hospital in warwick , ri .
all patients admitted to the care of the internal medicine teaching service during this period were eligible for chart review .
patients included in the analysis were required to be 19 years of age , to have a diagnosis of either type 1 or type 2 diabetes recorded in the emr at the time of hospital admission , and to have confirmed use of at least one chronic medication for the treatment of diabetes before admission .
data collected for analysis included patients age , ethnicity , sex , height , weight , smoking status , outpatient diabetes medication regimen , diabetes type , most recent a1c within the past 12 months , drug and nondrug allergies , and documented history of respiratory , cardiovascular , mental health , oncological , cerebrovascular , hepatic , and autoimmune comorbidities .
diagnoses for new comorbidities during the index hospitalization were not included because the impact of undiagnosed comorbid disease on immunization history would be unclear .
however , values for a1c , a marker of recent glycemic control , were included even if obtained during the index hospital stay .
emr entries for the patients were reviewed for nursing screening and intervention documentation from previous inpatient admissions to determine immunization history .
screening is performed by nursing staff at the time of patients admission to a specific nursing unit .
the screening protocol assesses all previous tetanus , ppsv23 , and hepatitis b immunizations , as well as influenza immunization within the past year .
the emr also contained outpatient prescription claims information obtained through contracts with pharmacy benefits providers .
adherence to the acip recommendations for influenza and pneumococcal vaccinations was assessed for all patients .
precautions related to or contraindications for vaccination , including allergies or severe hypersensitivities to vaccine components and a history of guillain - barr syndrome , were recorded .
immunization history comprised 12 months from the admission date for the influenza vaccination , with receipt of the vaccination within that time period representative of adherence to the annual influenza vaccination recommendation .
adherence to recommendations for the pneumococcal vaccine was determined based on patients age and the timing of previous vaccinations .
patients < 65 years of age must have received at least one dose to be considered adherent .
patients 65 years of age who had received one dose since turning 65 were considered adherent .
patients who were 65 years of age who had received a vaccination before turning 65 were considered adherent if that vaccination was received within the past 5 years or if they had received another vaccination since turning 65 .
patients between the ages of 19 and 59 years were evaluated for previous immunization with the hepatitis b vaccine .
patients documented as having received at least three doses of the hepatitis b vaccine were considered adherent .
patients having received at least one dose of the vaccine but less than three were considered nonadherent and labeled as
primary data analyses evaluated predictors of adherence to recommendations for each of the three vaccines . the student s t test was used to compare the means of continuous variables with equal variance .
satterthwaite s approximate t test was used to compare means of continuous variables with unequal variance .
analysis was used to compare categorical data if all cells contained values > 5 .
fisher s exact test was used for the comparison of categorical data involving at least one cell with a value 5 .
sas version 9.3 ( sas institute , cary , n.c . ) was used for the statistical analyses .
during the study period , 364 records were reviewed , and 100 patients with diabetes were identified as eligible for inclusion .
vaccine coverage rates and healthy people 2020 vaccine coverage goals are reported in table 1 .
the number of patients deemed appropriate to have received the hepatitis b vaccine was 39 ( 39% ) . of these , none had initiated or completed the three - dose vaccination series .
immunization adherence rates were 41% for the influenza vaccine , 37% for the pneumococcal vaccine , and 19% for both vaccines .
the odds ratio ( or ) for adherence to the influenza or pneumococcal vaccination recommendation was 1.97 ( 95% ci 0.864.50 ) if patients were also adherent to the other vaccination recommendation .
no complete contraindications to vaccination were recorded , although two patients had documented egg allergies .
patients demographic characteristics , diabetes - related variables , and the corresponding bivariate odds of adherence to vaccination recommendations are presented in table 2 and table 3 .
the groups did not differ significantly with regard to sex , age , or bmi .
the majority of patients ( 79% ) were current or former smokers , and 60% of patients had used insulin as an outpatient before admission .
patients with better glycemic control as indicated by an a1c value < 7% were slightly more likely to have received an influenza vaccination , although this finding did not reach statistical significance ( p = 0.11 ) .
the presence of individual comorbid diseases and an increasing total comorbid disease burden failed to predict adherence to influenza vaccination recommendations ( p > 0.99 ) .
the odds of adherence to the pneumococcal vaccination recommendation were nonsignificantly increased in the presence of individual comorbid diseases , with the exception of cancer , for which the odds decreased ( or 0.31 [ 95% ci 0.0821.16 ] ) .
the mean number of comorbid diseases present was significantly greater for patients adherent to the pneumococcal vaccination recommendation ( p < 0.01 ) .
demographic characteristics of patients with diabetes and the associated bivariate odds of adherence with immunization guidelines reference was absence of the comorbid disease .
diabetes - related characteristics of patients with diabetes and the associated bivariate odds of adherence with immunization guidelines a total of 23 patients did not have available a1c values .
this study found that patients at high risk for infection and infectious disease complications because of their history of diabetes were largely nonadherent to acip immunization recommendations .
the coverage rate of 41% for the influenza vaccine in this population is less than the estimated 47% rate in high - risk individuals ( defined as having either diabetes , asthma , or cardiovascular disease ) aged 1864 years nationally for the 20122013 season ( 24 ) .
the influenza vaccination rate in this study was also substantially less than the 66.2% rate reported for adults 65 years of age during the same time period ( 24 ) .
the pneumococcal vaccine coverage rate of 37% in this study approximated an average of 2011 national estimates of 66.5% for white adults 65 years of age and 20.1% for high - risk adults aged 1864 years ( 23 ) .
the absence of any patients adherent to recommendations for the hepatitis b vaccination in this study is inconsistent with the 26.9% national coverage estimate or people with diabetes from 2011 ( 23 ) .
immunization rates for all three vaccines failed to meet targets established by the healthy people 2020 initiative ( 22 ) .
the greater odds of pneumococcal vaccination associated with an increasing burden of comorbid disease aligns with other studies evaluating predictors of pneumococcal vaccination ( 27,28 ) . in this study , patients with comorbid diseases , including chronic heart , lung , and liver disease , as well as cigarette smoking , had multiple indications for pneumococcal vaccination , and providers may have been more likely to identify such patients as vaccination candidates . unlike previous predictive analyses , increasing age did not increase the odds of having received either vaccination .
this , in conjunction with lower mean bmi and a1c levels in adherent patients , suggests that influenza vaccination may be associated with other positive health management decisions .
the most noteworthy result of this study is the failure to immunize patients with diabetes with the hepatitis b vaccine .
this indicates that many providers may be unaware of the 2011 acip hepatitis b vaccination recommendation for this population .
expanding coverage for the influenza and pneumococcal vaccines has been a nationwide health goal since the original healthy people initiative began in 1979 ( 29 ) .
annual increases in pneumococcal and influenza vaccination rates were sustained throughout much of the past few decades ( 30,31 ) but have slowed in recent years ( 23,32 ) .
drivers of the increase in vaccination coverage include the use of health information technology for identification of unvaccinated patients , protocols for screening and administration , and extension of access to larger patient populations by increasing the number of immunizing providers and locations where vaccination services are available . increased coverage of preventive services under the affordable care act
health plans created after 23 september 2010 must provide full reimbursement without a patient copayment for acip - recommended immunizations ( 33 ) .
limitations differ among states regarding which vaccinations may be administered , whether a prescription or protocol is required , and the age of eligible patients .
the influenza vaccination may be administered to patients 19 years of age by pharmacists in all 50 states .
all states , with the exception of south dakota , allow pharmacist administration of the pneumococcal vaccine . in 45 states ,
pharmacy interns who have completed the immunization certificate training program and who are operating under the supervision of a pharmacist may administer vaccinations in 38 states ( 34,35 ) .
thus , using pharmacists to screen , educate , and immunize patients is an intervention amenable to multiple care settings .
the results of this study underscore the need for continued expansion of vaccination efforts to attain national goals for immunization coverage for the influenza , pneumococcal , and hepatitis b vaccines .
this study is believed to be the first to examine rates of hepatitis b vaccination in patients with diabetes since the release of the acip recommendation in october 2011 .
further research is required to assess changes in national coverage for the vaccination since that time . the use of data from an emr in this study enabled the evaluation of a multitude of potential demographic and health - related predictors of vaccination .
previous investigations have evaluated immunization rates in patient populations presenting to an emergency department ( ed ) and confirmed the feasibility of immunizing eligible patients during emergency visits ( 36,37 ) .
one prospective , cross - sectional study ( 37 ) conducted in an urban ed found that only 16 and 18% of presenting high - risk patients were up to date on influenza and pneumococcal vaccinations , respectively .
eligible patients were offered vaccinations during the ed visit , and the percentage of patients who were adherent on leaving the ed was improved to 83% for the influenza vaccine and 84% for the pneumococcal vaccine .
in contrast to ed interventions , our study evaluated immunization histories obtained at hospital admission , which would prompt subsequent offers for influenza or pneumococcal vaccination in eligible populations through a standing order protocol .
other studies have demonstrated the effectiveness of standing order protocols involving nurse , physician , and pharmacy practitioners in institutional settings for both the pneumococcal and influenza vaccines ( 38 ) .
prioritizing screening and administration of vaccinations during all points of patient contact can increase immunization coverage for acip - recommended vaccines in patients with diabetes and is an attainable goal for emergency , inpatient , and outpatient health care providers .
self - reported immunization history is subject to recall bias , with the potential for interviewer bias also to be present because of variability among practitioners in the meticulousness of their questioning of patients regarding past vaccinations . as a result
, there is a possibility that some patients who were uncertain of or misrepresented their vaccination history were misclassified .
the generalizability of this study is limited by its single - hospital design and lack of ethnic and geographic diversity in the patient population .
although the results are comparable to studies examining immunization rates and predictors of vaccination in nationally representative populations , vaccination procedures may differ markedly among regions and institutions .
in this study , rates of adherence to acip recommendations for influenza , pneumococcal , and hepatitis b immunization of patients with diabetes were all below national coverage estimates . increasing burden of comorbid disease predicted pneumococcal vaccination , whereas no significant predictors of influenza vaccination were identified .
allocation of health care resources to increase vaccine coverage should remain a priority , with a focus on spreading awareness of the acip hepatitis b vaccine recommendation for people with diabetes .
Output:
| in brief this single - center , cross - sectional study was designed to assess adherence to national guidelines for the immunization of patients with diabetes and to evaluate predictors of vaccination with the hepatitis b , influenza , and 23-valent pneumococcal polysaccharide vaccines . in patients
considered to be at increased risk for infection and infectious disease complications because of their history of diabetes , extensive nonadherence to immunization recommendations for all three vaccines was found .
nonadherence to the 2011 advisory committee on immunization practices recommendation for hepatitis b vaccination was ubiquitous .
allocation of health care resources to increase vaccine coverage should remain a priority , with a focus on spreading awareness of the hepatitis b vaccine recommendation for people with diabetes . |
PubmedSumm118613 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: recurrent spontaneous abortion ( rsa ) is defined as the miscarriage of two or more consecutive pregnancies with unknown origin within 20 weeks of pregnancy , affecting about 15% of reproductive age women , which is difficult to cure in clinical practice .
generally , rsa has been caused by recognized factors including genetics , endocrine , hormonal problems , infection , placental anomalies , smoking and alcohol consumption , exposure to environmental triggers , psychological trauma , and constant stressful emotion .
however , the cause for nearly half of the patients with rsa can not be explained .
many scientists have made trials on the treatment of rsa from many fields , such as genetics , endocrinology , and immunology [ 68 ] . with the rapid development of molecular biology technology ,
the focus has been shifted to the relationship between gene polymorphism and rsa , such as the relationships between micrornas ( mirnas ) and rsa .
some previous studies suggest that mirnas , by affecting endometrium , pre - eclampsia , and infertility , might be essential for the normal function of the reproductive system and provide noninvasively obtained diagnostic information .
mirnas are a class of small endogenous noncoding rnas that negatively regulate target gene transcription through hybridization to incomplete complementary sequences in the 3 untranslated region of their target mrnas .
previous evidence has shown the impact of mirnas on human reproduction . as an important member in the mirna family , mirna-27a
is actively expressed in many cancers , such as breast cancer , colorectal cancer , and gastric cancer , and is considered as an effective indicator for early diagnosis and prognosis of tumors [ 1618 ] .
accumulating evidence has demonstrated that single - nucleotide polymorphisms ( snps ) in mirna precursors may influence the expression levels of mirna .
recently , an important a to g transition snp in pre - mir-27a ( rs895819 ) was identified in common cancers .
leptin is the gene product of the obese gene and may regulate body weight , satiety , and fertility . the adipokine leptin is a lipostatic signal governing food intake and stimulating energy expenditure .
it is also a pivotal metabolic regulator , which correlates with the pro - inflammatory th1 immune response to energy balance and nutritional status . in recent years
, leptin regulation of immune response and inflammatory response has received much research attention due to its significant changes during infection and inflammation .
the human leptin gene is composed of three exons and two introns located on chromosome 7q31.3 , which spans ~18 kb of genomic dna .
leptin rs7799039 g / a was shown to be a common snp investigated in the association between leptin gene polymorphisms and plasma leptin level . however , due to the limited amount of examined mirna , and the scarcity of explorations into the effect of leptin on non - mammals , reports on the risks of rsa and its connection with gene polymorphism of mirna-27a and leptin has received less attention .
therefore , our present study intended to explore the effect of gene polymorphisms of mirna-27a and leptin on rsa , to evaluate the regulatory function of mirna in the process of pregnancy , and to discuss the effect and significance of the mirna-27a and leptin on rsa .
from may 2013 to april 2015 , a total of 138 rsa patients with a mean age of 28.834.57 years and menstrual cycle of 31.523.03 days , admitted to the obstetric clinic of shenzhen longhua new district central hospital , were recruited into our study as the case group .
all rsa cases were confirmed according to the diagnostic criteria , which were : ( 1 ) women with two or more consecutive spontaneous abortions ; ( 2 ) karyotypes of couples and chorionic villus sampling ( cvs ) after abortion showing normal ; ( 3 ) no abnormal anatomy of the reproductive tract ; ( 4 ) endocrine function such as sex hormone secretion and thyroid function presenting normal ; ( 5 ) negative autoantibodies , including anticardiolipin antibody , antinuclear antibody , antipaternal complement - dependent antibody ( apca ) and the toxoplasma ( tox ) , other ( oth ) , rubella virus ( ruv ) , cytomegalovirus ( cmv ) , and herpes simplex virus - ii ( hsv - ii ) ( torch ) ; ( 6 ) no thrombotic disease or thrombotic tendency ; and ( 7 ) no inflammatory response in the reproductive tract or systemic inflammatory response . during the same period
, we also recruited 142 normal pregnancy women as the control group , with a mean age of 29.124.33 years and menstrual cycle of 32.043.17 days .
the inclusion criteria for the control group were : ( 1 ) no history of spontaneous abortion ; ( 2 ) karyotypes of couples presenting normal ; and ( 3 ) at least one normal live birth and no pregnancy - related complications .
baseline characteristics of the subjects between the case and control groups show no significant differences ( both p>0.05 ) . also ,
we excluded patients with history of smoking , drinking , drug use , and family disease ; patients with chronic pain , reproductive tract abnormality , or endocrine disorder ; patients with severe cardio - cerebrovascular disease , liver and kidney dysfunction ; patients with comorbidity of depression and other mental disorders ; and patients with reoperation due to complications within the last three months .
this study was approved by the ethics committee of shenzhen longhua new district central hospital .
the peripheral blood ( 5 ml ) from each subject was placed in a tube containing ethylenediamine tetraacetic acid ( edta ) and stored at 80c .
with addition of erythrocytic segment , dna was extracted with the use of the blood genome dna extraction kit ( takara biotech co. , ltd . ,
dalian , china ) . polymerase chain reaction ( pcr ) amplification was conducted with primers of rs895819 a / g in mirna-27a and rs7799039 g / a in leptin , and the primers were designed by prime 5.0 software and then synthesized by shanghai sangon biotech co. , ltd .
the pcr reaction condition was : 94c for 2 min ; 35 cycles of 94c for 1 min , 52c for 1 min , and 72c for 1 min ; 72c extension for 5 min .
with column temperature of 59.3c and mobile phase flow rate of 0.9 ml / min , mirna-27a rs895819 a / g was genotyped through two steps ( figure 1 ) : ( 1 ) heterozygote ag exhibited bimodal dhplc ( figure 1a ) ; ( 2 ) pcr samples that exhibited unimodal dhplc mixed with equivalent aa samples verified by sequencing , and then the mixture was subject to dhplc analysis , with aa exhibiting unimodal and gg exhibiting bimodal ( figure 1b ) . a and g mutations were also confirmed by sequencing ( figure 1c ) .
leptin rs7799039 g / a was genotyped through two steps ( figure 2 ) : ( 1 ) heterozygote
ga displayed bimodal dhplc ( figure 2a ) ; ( 2 ) pcr samples that displayed unimodal dhplc mixed with equivalent gg samples as verified by sequencing , and then the mixture underwent dhplc analysis , with gg displaying unimodal and aa displaying bimodal ( figure 2b ) .
serum separated from the whole blood by centrifugation at 3000 rpm for 10 min at 4c was transferred into a centrifuge tube .
total rna ( trna ) was extracted from the serum using the mirvana paris kit ( ambion inc . , austen , tx , usa ) , and then reversely transcribed to obtained cdna using a reverse transcription system ( thermo fisher scientific fermentas , ma , usa ) . with the cdna as template , the primers of mirna-27a ( forward : 5 tgcggttcacagtggctaag 3 ; reverse : 5 ctcaactggtgtcgtgga 3 ) were used for pcr amplification . using the taq - man microrna kit ( ambion inc . ,
austen , tx , usa ) , every cdna sample obtained from rt - pcr was used to detect the expression level of mirna-27a in a fluorescence - based rt - qpcr instrument ( model 7900 ; applied biosystems inc .
, foster city , ca , usa ) . separated from whole blood by centrifugation at 3000 rpm for 10 min at 4c , plasma was transferred into a centrifuge tube .
the following procedures were all performed according to the kit ( r&d systems inc , minneapolis , mn , usa ) manual .
samples were brought to 37c , the elisa plate was coated with diluted plasma for 30 min , then to each hole we added 50 l enzyme liquid for 30 min .
subsequently , with the addition of 50 l chromogenic reagent a and 50 l reagent b , each hole was stored in the dark for 15 min .
it was appropriate to extend the coloration time if the color was too light . with 50 l stopping solution added into each hole , the color changed to yellow immediately .
the optical density ( od ) value was measured at a wavelength of 450 nm at 15 min after the termination .
the standard curve was drawn with od value as the abscissa and concentration as the ordinate , and concentrations of the standard product were 25 , 50 , 100 , 200 , 400 ng / l successively .
the optimal dilution ratio of other samples was predicted according to the concentration of plasma .
continuous data are expressed as mean standard deviation ( sd ) , with t test for comparison .
the test was also employed to identify whether samples between two groups met the hardy - weinberg equilibrium used to examine the representativeness of a study population .
odds ratio ( or ) with 95% confidence interval ( ci ) was calculated to estimate association between disease and polymorphism in single - factor and multi - factor logistic regression analyses .
from may 2013 to april 2015 , a total of 138 rsa patients with a mean age of 28.834.57 years and menstrual cycle of 31.523.03 days , admitted to the obstetric clinic of shenzhen longhua new district central hospital , were recruited into our study as the case group .
all rsa cases were confirmed according to the diagnostic criteria , which were : ( 1 ) women with two or more consecutive spontaneous abortions ; ( 2 ) karyotypes of couples and chorionic villus sampling ( cvs ) after abortion showing normal ; ( 3 ) no abnormal anatomy of the reproductive tract ; ( 4 ) endocrine function such as sex hormone secretion and thyroid function presenting normal ; ( 5 ) negative autoantibodies , including anticardiolipin antibody , antinuclear antibody , antipaternal complement - dependent antibody ( apca ) and the toxoplasma ( tox ) , other ( oth ) , rubella virus ( ruv ) , cytomegalovirus ( cmv ) , and herpes simplex virus - ii ( hsv - ii ) ( torch ) ; ( 6 ) no thrombotic disease or thrombotic tendency ; and ( 7 ) no inflammatory response in the reproductive tract or systemic inflammatory response . during the same period
, we also recruited 142 normal pregnancy women as the control group , with a mean age of 29.124.33 years and menstrual cycle of 32.043.17 days .
the inclusion criteria for the control group were : ( 1 ) no history of spontaneous abortion ; ( 2 ) karyotypes of couples presenting normal ; and ( 3 ) at least one normal live birth and no pregnancy - related complications .
baseline characteristics of the subjects between the case and control groups show no significant differences ( both p>0.05 ) . also ,
we excluded patients with history of smoking , drinking , drug use , and family disease ; patients with chronic pain , reproductive tract abnormality , or endocrine disorder ; patients with severe cardio - cerebrovascular disease , liver and kidney dysfunction ; patients with comorbidity of depression and other mental disorders ; and patients with reoperation due to complications within the last three months .
this study was approved by the ethics committee of shenzhen longhua new district central hospital .
the peripheral blood ( 5 ml ) from each subject was placed in a tube containing ethylenediamine tetraacetic acid ( edta ) and stored at 80c .
with addition of erythrocytic segment , dna was extracted with the use of the blood genome dna extraction kit ( takara biotech co. , ltd . ,
dalian , china ) . polymerase chain reaction ( pcr ) amplification was conducted with primers of rs895819 a / g in mirna-27a and rs7799039 g / a in leptin , and the primers were designed by prime 5.0 software and then synthesized by shanghai sangon biotech co. , ltd .
the pcr reaction condition was : 94c for 2 min ; 35 cycles of 94c for 1 min , 52c for 1 min , and 72c for 1 min ; 72c extension for 5 min .
with column temperature of 59.3c and mobile phase flow rate of 0.9 ml / min ,
mirna-27a rs895819 a / g was genotyped through two steps ( figure 1 ) : ( 1 ) heterozygote ag exhibited bimodal dhplc ( figure 1a ) ; ( 2 ) pcr samples that exhibited unimodal dhplc mixed with equivalent aa samples verified by sequencing , and then the mixture was subject to dhplc analysis , with aa exhibiting unimodal and gg exhibiting bimodal ( figure 1b ) . a and g mutations were also confirmed by sequencing ( figure 1c ) .
leptin rs7799039 g / a was genotyped through two steps ( figure 2 ) : ( 1 ) heterozygote ga displayed bimodal dhplc ( figure 2a ) ; ( 2 ) pcr samples that displayed unimodal dhplc mixed with equivalent gg samples as verified by sequencing , and then the mixture underwent dhplc analysis , with gg displaying unimodal and aa displaying bimodal ( figure 2b ) .
serum separated from the whole blood by centrifugation at 3000 rpm for 10 min at 4c was transferred into a centrifuge tube . total rna ( trna )
was extracted from the serum using the mirvana paris kit ( ambion inc . , austen , tx , usa ) , and then reversely transcribed to obtained cdna using a reverse transcription system ( thermo fisher scientific fermentas , ma , usa ) . with the cdna as template , the primers of mirna-27a ( forward : 5 tgcggttcacagtggctaag 3 ; reverse : 5 ctcaactggtgtcgtgga 3 ) were used for pcr amplification . using the taq - man microrna kit ( ambion inc . , austen , tx , usa ) , every cdna sample obtained from rt - pcr was used to detect the expression level of mirna-27a in a fluorescence - based rt - qpcr instrument ( model 7900 ; applied biosystems inc .
separated from whole blood by centrifugation at 3000 rpm for 10 min at 4c , plasma was transferred into a centrifuge tube .
the following procedures were all performed according to the kit ( r&d systems inc , minneapolis , mn , usa ) manual .
samples were brought to 37c , the elisa plate was coated with diluted plasma for 30 min , then to each hole we added 50 l enzyme liquid for 30 min .
subsequently , with the addition of 50 l chromogenic reagent a and 50 l reagent b , each hole was stored in the dark for 15 min .
it was appropriate to extend the coloration time if the color was too light . with 50 l stopping solution added into each hole , the color changed to yellow immediately .
the optical density ( od ) value was measured at a wavelength of 450 nm at 15 min after the termination .
the standard curve was drawn with od value as the abscissa and concentration as the ordinate , and concentrations of the standard product were 25 , 50 , 100 , 200 , 400 ng / l successively . the optimal dilution ratio of other samples was predicted according to the concentration of plasma .
continuous data are expressed as mean standard deviation ( sd ) , with t test for comparison .
the test was also employed to identify whether samples between two groups met the hardy - weinberg equilibrium used to examine the representativeness of a study population .
odds ratio ( or ) with 95% confidence interval ( ci ) was calculated to estimate association between disease and polymorphism in single - factor and multi - factor logistic regression analyses .
distributions of genotype and allele frequencies of mirna-27a rs895819 a / g and leptin rs7799039 g / a are presented in table 2 .
the test for hardy - weinberg equilibrium revealed an agreement of p value to the law of genetic equilibrium , which demonstrated that the study population was representative .
with respect to mirna-27a rs895819 a / g , the frequencies of gg genotype and g allele were both significantly higher in the case group than in the control group ( gg genotype : 15.9% vs. 9.2% , or ( 95%ci)=2.357 ( 1.095~5.075 ) , p=0.026 ; g allele : 37.7% vs. 27.1% , or ( 95% ci)=1.625 ( 1.137~2.324 ) , p=0.008 ) . for leptin rs7799039 g / a , the frequencies of aa genotype and a allele were also both higher in the case group than in the control group ( aa genotype : 47.8% vs. 32.4% , or ( 95% ci)=3.262 ( 1.461~7.279 ) , p=0.003 ; a allele : 69.9% vs. 57.4% , or ( 95% ci)=1.726 ( 1.218~2.446 ) , p=0.002 ) . with aa and non - aa genotypes of mirna-27a rs895819 a / g and gg and non - gg genotypes of leptin rs7799039 g / a as independent variables , and rsa patients as dependent variables , the bivariate logistic regression analyses were performed .
the results signified that non - aa genotypes of mirna-27a rs895819 a / g exhibited 2.732 times higher risk of rsa compared with aa genotype ( 95% ci=1.625~4.596 , p=0.000 ) .
non - gg genotypes of leptin rs7799039 g / a showed 4.081 times higher risk of rsa compared with gg genotype ( 95% ci=1.817~9.164 , p=0.001 ) ( table 3 ) .
we found that , compared to individuals with aa - gg combined genotypes , gg - aa carriers had 4.714 times ( 95% ci=1.077~20.63 , p=0.034 ) and ag - aa carriers had 3.480 times ( 95% ci=1.114~10.87 , p=0.028 ) higher risk of rsa . however , other related gene combinations interacting with the risk of rsa exhibited no significant difference ( table 4 ) .
we analyzed the clinical data collected from the 138 patients with rsa , and found that , compared with patients with aa genotype of mirna-27a rs895819 a / g , patients with ag + gg genotype suffered more intense pregnant reactions , shorter duration of miscarriage in pregnancy , more frequent abortion , and longer interval to next pregnancy ( all p<0.05 ) , indicating that there were significant differences in clinical features between patients with g allele and those with non - g allele .
also , compared to patients with gg genotype of leptin rs7799039 g / a , patients with ga + aa genotype suffered more intense pregnant reactions , shorter duration of miscarriage in pregnancy , more frequent abortion , and lengthened interval to next pregnancy ( all p<0.05 ) , revealing that there were also significant differences in clinical features between patients with a allele and those with non - a allele ( table 5 ) .
mirna-27a was expressed in the patients with aa genotype and ag + gg genotype of rs895819 a / g in both case group and control group , with a significant difference in its total expression volume between the control group ( 0.500.09 ) and the case group ( 1.300.13 ) ( p<0.01 ) ( figure 3a ) . in the control group ,
subjects with aa genotype had mirna-27a expression of 0.490.08 , lower than the 0.520.09 ( p=0.037 ) in those with ag + gg genotype . in the case group ,
mirna-27a expression of patients with aa genotype was 1.270.12 , lower than the 1.320.13 ( p=0.024 ) in patients with ag + gg genotype .
plasma leptin level of patients with gg genotype and ga + aa genotype rs7799039 g / a was much different ( p<0.01 ) between the case group ( 6.740.56 ) ng / ml and control group ( 4.990.39 ) ng / ml ( figure 3b ) .
in the control group , leptin level in the subjects with gg genotype was ( 4.870.36 ) ng / ml , slightly lower than the 5.010.39 ng / ml in subjects with ga + aa genotype ( p=0.101 ) . in the case group ,
leptin level in the patients with gg genotype was ( 6.380.45 ) ng / ml , lower than the 6.770.56 ng / ml ( p=0.026 ) in patients with ga + aa genotype ( table 6 ) .
distributions of genotype and allele frequencies of mirna-27a rs895819 a / g and leptin rs7799039 g / a are presented in table 2 .
the test for hardy - weinberg equilibrium revealed an agreement of p value to the law of genetic equilibrium , which demonstrated that the study population was representative .
with respect to mirna-27a rs895819 a / g , the frequencies of gg genotype and g allele were both significantly higher in the case group than in the control group ( gg genotype : 15.9% vs. 9.2% , or ( 95%ci)=2.357 ( 1.095~5.075 ) , p=0.026 ; g allele : 37.7% vs. 27.1% , or ( 95% ci)=1.625 ( 1.137~2.324 ) , p=0.008 ) . for leptin rs7799039 g / a , the frequencies of aa genotype and a allele were also both higher in the case group than in the control group ( aa genotype : 47.8% vs. 32.4% , or ( 95% ci)=3.262 ( 1.461~7.279 ) , p=0.003 ; a allele : 69.9% vs. 57.4% , or ( 95% ci)=1.726 ( 1.218~2.446 ) , p=0.002 ) .
with aa and non - aa genotypes of mirna-27a rs895819 a / g and gg and non - gg genotypes of leptin rs7799039 g / a as independent variables , and rsa patients as dependent variables , the bivariate logistic regression analyses were performed .
the results signified that non - aa genotypes of mirna-27a rs895819 a / g exhibited 2.732 times higher risk of rsa compared with aa genotype ( 95% ci=1.625~4.596 , p=0.000 ) .
non - gg genotypes of leptin rs7799039 g / a showed 4.081 times higher risk of rsa compared with gg genotype ( 95% ci=1.817~9.164 , p=0.001 ) ( table 3 ) .
we found that , compared to individuals with aa - gg combined genotypes , gg - aa carriers had 4.714 times ( 95% ci=1.077~20.63 , p=0.034 ) and ag - aa carriers had 3.480 times ( 95% ci=1.114~10.87 , p=0.028 ) higher risk of rsa .
however , other related gene combinations interacting with the risk of rsa exhibited no significant difference ( table 4 ) .
we analyzed the clinical data collected from the 138 patients with rsa , and found that , compared with patients with aa genotype of mirna-27a rs895819 a / g , patients with ag + gg genotype suffered more intense pregnant reactions , shorter duration of miscarriage in pregnancy , more frequent abortion , and longer interval to next pregnancy ( all p<0.05 ) , indicating that there were significant differences in clinical features between patients with g allele and those with non - g allele .
also , compared to patients with gg genotype of leptin rs7799039 g / a , patients with ga + aa genotype suffered more intense pregnant reactions , shorter duration of miscarriage in pregnancy , more frequent abortion , and lengthened interval to next pregnancy ( all p<0.05 ) , revealing that there were also significant differences in clinical features between patients with a allele and those with non - a allele ( table 5 ) .
mirna-27a was expressed in the patients with aa genotype and ag + gg genotype of rs895819 a / g in both case group and control group , with a significant difference in its total expression volume between the control group ( 0.500.09 ) and the case group ( 1.300.13 ) ( p<0.01 ) ( figure 3a ) . in the control group ,
subjects with aa genotype had mirna-27a expression of 0.490.08 , lower than the 0.520.09 ( p=0.037 ) in those with ag + gg genotype . in the case group ,
mirna-27a expression of patients with aa genotype was 1.270.12 , lower than the 1.320.13 ( p=0.024 ) in patients with ag + gg genotype .
plasma leptin level of patients with gg genotype and ga + aa genotype rs7799039 g / a was much different ( p<0.01 ) between the case group ( 6.740.56 ) ng / ml and control group ( 4.990.39 ) ng / ml ( figure 3b ) . in the control group , leptin level in the subjects with gg genotype was ( 4.870.36 ) ng / ml , slightly lower than the 5.010.39 ng / ml in subjects with ga + aa genotype ( p=0.101 ) .
in the case group , leptin level in the patients with gg genotype was ( 6.380.45 ) ng / ml , lower than the 6.770.56 ng / ml ( p=0.026 ) in patients with ga + aa genotype ( table 6 ) .
the etiology of rsa is complicated , involving genetics , endocrine , hormonal problems , placental anomalies , psychological trauma , and constant stressful emotion . in recent years
, some new ideas were put forward from the perspective of immunology and genetics , considering that the causes of rsa are related with gene polymorphism . due to the scarcity of literature on the relationship between mirna and leptin , and the risk of rsa
, we expected to make a comprehensive evaluation on the relationship between rsa and gene polymorphism of mirna and leptin .
our results revealed the case group had a significantly higher frequency of g allele gene and gg genotype distributed on mirna-27a rs895819 a / g in comparison with the control group .
there was also a significant up - regulation in the frequency of a allele gene and aa genotype of leptin rs7799039 g / a .
consequently , we concluded that mutation of g gene of mirna-27a rs895819 a / g and mutation of gene a of leptin rs7799039 g / a might increase the risk of rsa . as an important component of the mirna class , mirna-27a is closely related to the development of diseases , notably tumors , cardiovascular diseases , and metabolic diseases .
recent studies have shown that the irregular expression of mirnas might lead to recurrent miscarriage .
as a kind of protein mainly secreted by fat cells and involved in energy intake and balance of protein , leptin can influence the female reproductive endocrine system , regulate the hypothalamus - pituitary - gonadal axis , affect reproductive function and female ovulation , and participate in pubertal behavior , which plays a complex role in physiological regulation in connection with vegetative and reproductive metabolism .
mounzih et al . found that leptin may directly or indirectly regulate the formation of blood vessels by affecting vascular permeability and formation of endothelial cells and trophoblastic cells in the process of forming placenta .
further research deepened insights into the impact of mirna and leptin gene polymorphisms on cancers , and yang et al .
has found that the protective effect of single - nucleotide polypeptide rs895819 distributed on the end ring of mirna - g allele gene might decrease the possibility of gene mutation of mirna-27a with carcinogenesis , thus reducing the risk for familial breast cancer and presents possible hormone - related effects .
the polymorphism of leptin rs7799039 g / a had a significant association with antipsychotic drug - induced weight gain .
has reported that a common polymorphism in leptin rs7799039 g / a has an effect on the expression of leptin , possibly at the transcriptional level , and therefore also adipose secretion levels of the hormone .
it is also reported by mamms et al . that the a allele of leptin rs7799039 g / a polymorphism was demonstrated to be associated with higher leptin levels before diet and lower bmi loss in women .
a previous study found that the aa genotype of rs7799039 g / a polymorphism and higher circulating leptin level may be associated with preeclampsia / pregnancy - induced hypertension , further leading to the occurrence of rsa .
additionally , the secretion of leptin is positively correlated with body mass , and winnie et al .
reported that maternal obesity is an independent factor related to a higher risk of rsa , suggesting that leptin polymorphism may directly or indirectly contribute to the development of rsa .
interestingly , reports on the risks of rsa and its connection with gene polymorphism of mirna-27a and leptin remain scarce .
our logistic regression analysis showed that compared with individuals with combined aa - gg genotype distributed on mirna-27a rs895819 a / g locus and leptin rs7799039 g / a locus , patients with combined genotype of gg - aa and ag - aa had a higher risk of rsa , which further demonstrates the close ties between rsa and gene polymorphism of mirna-27a and leptin .
our study revealed polymorphisms of mirna-27a rs895819 a / g and leptin rs7799039 g / a may contribute to an increased risk of rsa .
given the complicated etiology of rsa , other external triggers might have interfered with our results .
Output:
| backgroundthe aim of this study was to investigate the possible associations of mirna-27a and leptin polymorphisms with the risk of recurrent spontaneous abortion ( rsa).material / methodsbetween may 2013 and april 2015 at shenzhen longhua new district central hospital , we randomly recruited 138 rsa patients as the case group and another 142 normal pregnancy women as the control group .
we used denaturing high - performance liquid chromatography ( dhplc ) to determine the genotypes and allele frequencies of mirna-27a rs895819 a / g and leptin rs7799039 g / a.resultsthe gg genotype and g allele frequencies of mirna-27a rs895819 a / g were higher in the case group than in the control group , and the aa genotype and a allele frequencies of leptin rs7799039 g / a were also higher in the case group than in the control group ( all p<0.05 ) .
mirna-27a rs895819 a / g and leptin rs7799039 g / a polymorphisms increased the risk of rsa ( exp ( b)=2.732 , 95% ci=1.625~4.596 , p=0.000 ; exp ( b)=4.081 , 95% ci=1.817~9.164 , p=0.001 ) .
gg - aa or ag - aa carriers had a higher risk of rsa .
the mirna-27a expression of aa carriers of mirna-27a rs895819 was lower than that of ag+gg carriers both in the case and control groups ( all p=0.024 ) .
the plasma leptin concentration of gg carriers was lower than that of ga+aa carriers in the case group ( p=0.026).conclusionsthe polymorphisms of mirna-27a rs895819 a / g and leptin rs7799039 g / a may contribute to an increased risk of rsa . |
PubmedSumm118614 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
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the input is a biomedical literature
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the output is the summary of an input biomedical literature in six sentences
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Input: oral cancers rank sixth among the common malignancies globally , with a rising titer of around 40% in developing countries such as southeast asia . among these ,
90% of all oral cancers are squamous cell carcinoma ( scc ) originating from the mucosal epithelium .
a large number of dna and rna viruses have proved to be oncogenic in a wide variety of animals , ranging from amphibia to primates , and the evidence grows stronger that certain forms of human cancer are of viral origin although scientific knowledge in viral oncology has exploded in the 20 century , the role of bacteria as mediators of oncogenesis is less well elucidated . as cancer continues its climb as the leading cause of death in developed nations , understanding the long - term effects of bacteria has become increasingly important as a possible means of cancer prevention .
however , it was not until the late 20 century that reproducible , peer - reviewed work definitively identified a bacterial cause of malignancy .
interest in the possible relationships between bacteria and the different stages of cancer development has been increased since the classification by the world health organization of helicobacter pylori as a definite ( class 1 ) carcinogen .
the three main examples are infection with the bacterium helicobacter pylori leading to an elevated risk of developing pancreatic cancer , gastric adenocarcinoma and gastric lymphoma , infection with particular types of human papilloma virus ( hpv ) leading to cervical cancer , tonsillar carcinoma and some cases of oral squamous cell carcinoma ( oscc ) and chronic hepatitis b and c infections leading to hepatocellular carcinoma .
ever since 1890 , when the pathologist william russell described a characteristic organism of cancer , there has been a small but dedicated group of scientists who have claimed that bacteria ( not viruses ) cause cancer .
their reports showed an unusual microbe that can be seen microscopically in cancer tissue and cultured from cancerous tumors and blood .
the idea that bacteria cause major forms of cancer was discarded a hundred years ago by the medical establishment and is still regarded as scientific heresy .
nevertheless , this communication provides evidence that cancer microbes can be demonstrated microscopically in cancer tissue .
livingston was the physician in 1974 who found that cancer bacteria could produce the fetal growth hormone hcg . adding to this discovery were the findings of other independent researchers who discovered that cancer cells are also capable of producing or synthesizing hcg .
cancer bacteria display intracellular parasitism during certain life - cycle phases and can invade healthy cells .
they can also secrete toxic chemical fractions such as actinomycin - d , which may result in karyotypic changes , resulting in malignancy .
after the onset of cancer , bacteria act in concert with cancer cells and , in a way that is not fully understood , help cancer cells synthesize hcg .
hcg is a universal cancer marker that also acts as a protective hormone for the cancer cell .
hcg is a universal cancer marker that also acts as a protective hormone for the cancer cell .
there is increasing evidence that some pathogenic bacteria can contribute to specific stages in cancer development , particularly in chronic infections where , for the duration of the infection , normal cell processes can come under the influence of factors released by the pathogen .
an overwhelming body of evidence has determined that relationships among certain bacteria and cancers exist .
their role , however , is still unclear . convincing evidence links some species to carcinogenesis while others appear promising in the diagnosis , prevention or treatment of cancers .
the complex relationship between bacteria and humans is demonstrated by helicobacter pylori and salmonella typhi infections .
research has shown that helicobacter pylori can cause gastric cancer or malt lymphoma in some individuals .
in contrast , exposure to helicobacter pylori appears to reduce the risk of esophageal cancer in others .
salmonella typhi infection has been associated with the development of gallbladder cancer ; however , salmonella typhi is a promising carrier of therapeutic agents for melanoma and colon and bladder cancers .
thus , bacterial species and their roles in particular cancers appear to differ among different individuals .
many species , however , share an important characteristic : highly site - specific colonization . this critical factor may lead to the development of noninvasive diagnostic tests , innovative treatments and cancer vaccines . it has been reported that the majority of cases of head and neck cancer can be related to tobacco use and heavy alcohol consumption .
other possible risk factors include viral infections , poor oral hygiene and infection with candida species .
the latter microorganisms are associated with some forms of leukoplakic lesions , the presence of which has long been recognized as an independent risk factor for carcinoma .
the involvement of other microorganisms , particularly bacteria , has not been studied to any great extent .
certain glycoconjugates serve as receptors for specific bacteria , and recent reports support the notion that shifts in the colonization of different cancer cells are associated with observed changes in cell surface receptors .
it is now recognized that bacteria bind to and colonize the mucosal surfaces in a highly selective manner via a lock and key mechanism .
adhesins on bacteria bind specifically to complementary receptors on the mucosal surfaces of the host .
these adhesins differ from species to species , leading to specificity in attachment to different surfaces .
studies have shown that even within genera , colonization patterns of individual species may differ markedly ; streptococcus salivarius , for example , preferentially colonized the oral soft tissues and saliva compared with the teeth , while the reverse was true of streptococcus sanguis .
bacterial infections have been linked to malignancies due to their ability to induce chronic inflammation .
there have been increasing data to confirm that bacterial infections rely upon precise interactions between the pathogens and the components of the host cell regulatory systems that are given below .
it has been shown that several bacteria can cause chronic infections or produce toxins that disturb the cell cycle and lead to altered cell growthchronic infections induce cell proliferation and dna replication through activation of mitogen - activated kinase pathways and cyclin d1 and increase the incidence of cell transformation rate of tumor development through increased rate of genetic mutationseveral infections cause intracellular accumulation of the pathogen , leading to suppression of apoptosis primarily through modulation of the expression of bcl-2 family proteins or by inactivation of retinoblastoma protein , prb .
this strategy provides a niche in which the intracellular pathogen can survive in spite of the attempts of the host immune system to destroy the infected cells by apoptosis .
thus , it allows the partially transformed cells to evade the self - destructive process and progress to a higher level of transformation , ultimately becoming tumorogenicmany pathogenic bacteria causing chronic infection with intracellular access subvert host cell signaling pathways , enhancing the survival of the pathogen .
it has been shown that several bacteria can cause chronic infections or produce toxins that disturb the cell cycle and lead to altered cell growth chronic infections induce cell proliferation and dna replication through activation of mitogen - activated kinase pathways and cyclin d1 and increase the incidence of cell transformation rate of tumor development through increased rate of genetic mutation several infections cause intracellular accumulation of the pathogen , leading to suppression of apoptosis primarily through modulation of the expression of bcl-2 family proteins or by inactivation of retinoblastoma protein , prb .
this strategy provides a niche in which the intracellular pathogen can survive in spite of the attempts of the host immune system to destroy the infected cells by apoptosis .
thus , it allows the partially transformed cells to evade the self - destructive process and progress to a higher level of transformation , ultimately becoming tumorogenic many pathogenic bacteria causing chronic infection with intracellular access subvert host cell signaling pathways , enhancing the survival of the pathogen .
the regulation of these signaling factors is central to the development or inhibition of tumor formation .
such infections can mimic some of the gross effects seen in tumorogenesis , and indeed the precancerous lesion formed in such infections can regress with antibiotic treatment and clearance of bacteria .
another possible mechanism is the metabolism of potentially carcinogenic substances by the bacteria .
this is of relevance in the oral cavity , where the preexisting local microflora may facilitate tumourogenesis by converting ethanol into its carcinogenic derivative , acetaldehyde , to levels capable of inducing dna damage , mutagenesis and secondary hyperproliferation of the epithelium .
this is of relevance in the oral cavity , where the preexisting local microflora may facilitate tumourogenesis by converting ethanol into its carcinogenic derivative , acetaldehyde , to levels capable of inducing dna damage , mutagenesis and secondary hyperproliferation of the epithelium . also , this is evidential from the increased levels of microbial acetaldehyde production in heavy drinkers and smokers , supporting this concept .
microbial carcinogenesis may also involve nitrosation , in which microbial cells catalyze the formation of n - nitroso compounds from the precursor 's nitrite and amines , amides or other nitrosatable compounds .
several species of bacteria encompass strains capable of catalyzing nitrosation , in particular , escherichia coli also , yeasts and fungi may include nitrosating organisms .
this particular nitrosamine appears to be a relevant candidate for the cause of carcinoma , not only of the esophagus but also of other mucosal areas such as the oral cavityrecent studies have shown that podoplanin , a transmembrane glycoprotein , is expressed in various normal as well as neoplastic tissues .
butyric acid ( ba ) , an extracellular metabolite from periodontopathic bacteria , plays an important role in the progression of periodontal disease .
ba / sodium butyrate ( nab ) increases podoplanin expression and cell migration in certain oral squamous cell carcinoma ( oscc ) cell lines , suggesting that the progression of periodontal disease may promote the progression of oscc via a podoplanin - dependent pathwaycertain bacterial infections may evade the immune system or stimulate immune responses that contribute to carcinogenic changes through the stimulatory and mutagenic effects of cytokines released by inflammatory cellsthese include reactive oxygen species ( ros ) , interleukin-8 ( il-8 ) , cyclooxygenase-2 ( cox-2 ) , reactive oxygen species ( ros ) and nitric oxide ( no ) .
microbial carcinogenesis may also involve nitrosation , in which microbial cells catalyze the formation of n - nitroso compounds from the precursor 's nitrite and amines , amides or other nitrosatable compounds .
several species of bacteria encompass strains capable of catalyzing nitrosation , in particular , escherichia coli also , yeasts and fungi may include nitrosating organisms .
this particular nitrosamine appears to be a relevant candidate for the cause of carcinoma , not only of the esophagus but also of other mucosal areas such as the oral cavity recent studies have shown that podoplanin , a transmembrane glycoprotein , is expressed in various normal as well as neoplastic tissues .
butyric acid ( ba ) , an extracellular metabolite from periodontopathic bacteria , plays an important role in the progression of periodontal disease .
ba / sodium butyrate ( nab ) increases podoplanin expression and cell migration in certain oral squamous cell carcinoma ( oscc ) cell lines , suggesting that the progression of periodontal disease may promote the progression of oscc via a podoplanin - dependent pathway certain bacterial infections may evade the immune system or stimulate immune responses that contribute to carcinogenic changes through the stimulatory and mutagenic effects of cytokines released by inflammatory cells these include reactive oxygen species ( ros ) , interleukin-8 ( il-8 ) , cyclooxygenase-2 ( cox-2 ) , reactive oxygen species ( ros ) and nitric oxide ( no ) .
chronic stimulation of these substances along with environmental factors such as smoking or a susceptible host appears to contribute significantly to carcinogenesis .
there is indeed a delicate balance between the microbial flora and our immune system , which allows the microbial flora to live as a commensal organism with us .
but , when disease occurs , these microbial flora become aggressive , giving rise to a host of diseases , some of which are inflammatory , while others are degenerative , cancerous or transitory .
studies reveal that , relative to the contiguous healthy oral mucosa , the human oral carcinoma surface biofilms harbored significantly increased levels of both aerobes and anaerobes .
many cancer centers have reported an increase in quinolone - resistant bacteria ( primarily escherichia coli and pseudomonas aeruginosa ) in patients receiving quinolone prophylaxis .
high levels of colonization of oscc by facultative oral streptococci were observed in the saliva of oscc subjects ( sasaki et al .
more recently , viable bacteria have been isolated from both superficial and deep portions of the oscc ( hooper et al . , 2006 ; hooper et al . , 2007 ) ,
the role of bacteria in the development of oral cancer has not been delineated , but the persistent presence of bacteria at tumor sites in the oral cavity raises intriguing questions about the role of bacteria in the progression of oscc .
unfortunately , most of such studies to date have included only cultured oral bacterial species , using classical cloning and sequencing approaches ( nagy et al .
, 1998 ; mager et al . , 2005 ; hong et al . , 2006 ) . to establish the association of oral bacteria in the progression of oscc , the complete bacterial profile ( cultured and uncultured ) in the oral cavity of oscc subjects needs to be first determined
, no large differences were observed for the biofilm flora at the tumor and control sites when the distributions of aerobic species were investigated .
almost similar species were found with the same frequency at both sites ( both tumor and normal sites ) , with the exceptions of serratia liquefaciens , klebsiella pneumoniae and citrobacter freundii from the gram negative species and streptococcus j - haemolyticus and enterococcus faecalis from the gram positive bacteria , which were present more frequently at the tumor sites .
anaerobic bacteria with known pathogenic features , such as actinomyces , clostridium , fusobacterium , prevotella , porphyromonas and members of the bacteroides ureolyticuslgracilis group , were involved in the biofilm formation on the tumor surface , while they were found only occasionally on the healthy mucosa surface of the same patient .
veillonella , a known member of the normal oral flora , was also isolated from twice as many lesion sites as control sites ( 18 versus nine ) . in one patient ,
( 2005 ) reported that several species detected in the nontumoros control tissue were not detected in the tumor tissues , and vice versa .
for instance , exiguobacterium oxidotolerans , prevotella melaninogenica , staphylococcus aureus , veillonella parvula and species of bacteria and micrococcus were isolated only from tumoros specimens and not at all from nontumoros ones .
conversely , moraxella osloensis , prevotella veroralis and species of actinomyces were grown only from nontumoros tissues .
this could indicate that while bacteria are present within all the oral mucosal tissues , there are potentially significant differences between the microfloras within tumoros compared with nontumoros mucosae .
in many studies , it was noticed that smoking and alcohol consumption were commonly associated with carcinoma of the palate , while that of chewing tobacco was commonly associated with carcinoma of the alveolus and buccal mucosa .
it has been stated that alcohol is not carcinogenic , but there is increasing evidence that a major part of the tumor - promoting action of alcohol might be mediated via its first , toxic and carcinogenic metabolite , acetaldehyde .
acetaldehyde is produced from ethanol in the epithelia by mucosal alcohol dehydrogenases , but much higher levels are derived from microbial oxidation of ethanol by the oral microbial flora .
thus , subjects consuming alcohol are at increased risk of developing cancer because of this synergistic action .
gram positive bacteria and yeasts are associated with higher acetaldehyde production , which could be a biologic explanation for the observed synergistic carcinogenic action of alcohol and smoking on upper gastrointestinal tract cancer .
this may open a new microbiologic approach to the pathogenesis of the cancer of the oral cavity and upper gastrointestinal tract .
streptococcus intermedius , prevotella , capnocytophaga and candida albicans were isolated in increased numbers at carcinoma sites .
( 2005 ) assessed the frequency of streptococcus anginosus infection in oral cancer tissues and investigated its infection route .
streptococcus anginosus dna was frequently detected in squamous cell carcinoma ( 19/42 ) , but not in other types of cancer ( lymphoma and rhabdomyosarcoma ) or leukoplakia samples .
a subject - based analysis revealed that streptococcus anginosus was solely detected in dental plaque and not in saliva from all 19 streptococcus anginosus - positive squamous cell carcinoma cases .
further , the genotype of streptococcus anginosus isolated from cancer tissue was identical to that from dental plaque of the same patients .
they concluded that infection of streptococcus anginosus could occur frequently in oscc and that dental plaque could be a dominant reservoir of the streptococcus anginosus bacteria . according to a study by mager et al .
( 2005 ) , devlin pm investigated whether the salivary counts of 40 common oral bacteria in subjects with an oscc lesion would differ from those found in cancer - free ( oscc - free ) controls .
unstimulated saliva samples were collected from 229 oscc - free and 45 oscc subjects and evaluated for their content of 40 common oral bacteria using checkerboard dna dna hybridization .
they concluded that high salivary counts of capnocytophaga gingivalis , prevotella melaninogenica and streptococcus mitis may be diagnostic indicators of oscc . in a review , mager et al .
( 2006 ) concluded that certain bacterial infections may evade the immune system or stimulate immune responses that contribute to carcinogenic changes through the stimulatory and mutagenic effects of cytokines released by inflammatory cells .
bacterial toxins can kill cells or , at reduced levels , alter cellular processes that control proliferation , apoptosis and differentiation .
these alterations are associated with carcinogenesis and may either stimulate cellular aberrations or inhibit normal cell controls . in 2006 , hooper et al .
conducted a study with the primary objective to identify any bacterial species within the oscc tissue using a standard microbiological culture approach . at the time of surgery
, a 1 cm portion of tissue was harvested from deep within the tumor mass using a fresh blade for each cut .
notably , some species were isolated only from either the tumoros or the nontumoros tissue type , indicating a degree of restriction .
successful surface decontamination of the specimens indicates that the bacteria detected were from within the tissue .
hooper et al . in 2007 conducted a study where , in order to characterize the bacterial microbiota present within the oral cancerous lesions , tumoros and nontumoros mucosal tissue specimens ( approximately 1 cm ) were harvested from 10 oscc patients at the time of surgery .
bacteria were visualized within sections of the oscc by performing fluorescent in situ hybridization with the universal oligonucleotide probe , eub338 .
this was then used as a template for polymerase chain reaction ( pcr ) with three sets of primers , targeting the 16s rrna genes of spirochaetes , bacteroidetes and the domain bacteria .
differences between the composition of the microbiotas within the tumoros and nontumoros mucosae were apparent , possibly indicating selective growth of bacteria within the carcinoma tissue .
whether the presence of these bacteria within the mucosa has any bearing on the carcinogenic process is a concept worthy of further investigation . in a case control study , rajendra et al .
( 2009 ) evaluated the role of helicobacter pylori in the etiology of mucosal inflammation , a condition that compounds the morbid state associated with oral submucous fibrosis .
a rapid urease test ( rut ) of plaque samples was performed to estimate the helicobacter pylori bacterial load .
they concluded that the contribution of helicobacter pylori in dental plaque to mucosal inflammation and periodontal disease was significant .
logistic regression analysis showed gastrointestinal disease and poor oral hygiene as being the greatest risk factors for bacterial colonization , irrespective of the subject groups .
a positive correlation exists between rut reactivity and the frequency of mucosal inflammation . in 2009 ,
fernando and jayakumar et al . undertook a study to determine the presence of helicobacter pylori in the oral lesions of 30 oral cancer patients and to determine the presence of igg antibodies to helicobacter pylori in oral cancer patients who are betel chewers , nonbetel chewers , healthy betel chewers and healthy nonbetel chewers , and to compare the presence of helicobacter pylori in these four groups .
one hundred and seventy - three subjects , of whom 53 were patients presenting with oral cancer to the cancer institute maharagama , 60 were healthy betel chewers and 60 were healthy nonbetel chewers from the religious and welfare service centre maharagama , were tested for helicobacter pylori by serology .
thirty oral biopsies from oral cancer patients were cultured under microaerophilic conditions to isolate helicobacter pylori .
of the 53 oral cancer patients , 44 were betel chewers . among the 53 oral cancer patients examined , 10 of 44 ( 22.7% ) patients who are betel chewers and four of nine ( 44.4% ) patients who are nonbetel chewers were detected to be positive for igg antibody against helicobacter pylori . in the healthy group ( betel chewers and nonbetel chewers ) , 10/60 ( 16.7% ) of the healthy betel chewers tested positive for helicobacter pylori by serology .
fourteen ( 26.4% ) of the oral cancer patients tested positive for helicobacter pylori by serology , of whom two were also culture positive ( only 30 samples were cultured ) .
the presence of helicobacter pylori in betel chewers ( with or without cancer ) compared with nonbetel chewers was statistically significant ( chi - square test , p < 0.05 ) .
the use of tobacco and areca nut in betel chewers was significant with the presence of helicobacter pylori ( p < 0.05 ) .
the oral cavity has been considered a potential reservoir for helicobacter pylori , from where the organism causes recurrent gastric infections .
they conclude from their study that there is a significantly higher proportion of helicobacter pylori in betel chewers compared with nonbetel chewers but not between oral cancer patients compared with patients without oral cancer .
hence , betel chewing may predispose to colonization with helicobacter pylori in the digestive tract through swallowing the quid or during betel chewing .
jukka in 2010 concluded in a review that microbial populations on the oral mucosa differ between healthy and malignant sites and certain oral bacterial species have been linked with malignancies , but the evidence is still weak in this respect .
nevertheless , oral microorganisms inevitably up - regulate cytokines and other inflammatory mediators that affect the complex metabolic pathways , and may thus be involved in carcinogenesis .
chocolatewala et al . in 2010 concluded in a review that studies have shown diversity of isolated bacterial taxa between the oral cancer tissue specimens and the control , with exiguobacterium oxidotolerans , pseudomonas melaninogenica , staphylococcus aureus and veillonella parvula being specific for tumorigenic tissues .
streptococcus anginosus , commonly linked with esophageal and pharyngeal cancers , is not of significance in oral cancers .
similarly , significant salivary specificity is noted for three bacteria , namely candida gingivalis , pseudomonas melaninogenica and streptococcous mitis , in oral cancer patients , making these species salivary markers for the early detection of oral cancers and thus improving the survival rate significantly .
pushalkar et al . in 2011 concluded that the most prevalent genera in the oscc library were streptococcus , gemella , rothia , peptostreptococcus , porphyromonas and lactobacillus .
to understand the role of bacteria in the development of oral cancer , the first step is to identify both cultured and uncultured organisms in the saliva as these organisms have the potential to cause inflammation that may support oscc progression .
anand et al . in 2011 conducted a hospital - based , case control study on 20 patients with newly diagnosed oral cancer and 20 healthy controls without any cancer to evaluate the associations between helicobacter pylori infection and oral cancer using culture and 16srna pcr technique for bacterial identification .
helicobacter pylori was identified by culture in one control ( 1/20 ) and three cases ( 3/20 ) .
the presence of helicobacter pylori was confirmed by pcr of the cultured organism and various biochemical tests .
however , the results of the pilot study support the association of helicobacter pylori with oral cancers , although the odds ratio is not statistically significant and the strength of the association suggests a possible association with high - risk behavior in oral cancer cases .
furthermore , it was found that helicobacter pylori dna was not unique to cancerous oral tissue as pcr from controls was also positive for two of 20 controls .
although a cause - and - effect relationship can not be inferred from this study , our findings can serve as a pilot study for further studies of helicobacter pylori .
( 2014 ) assessed the microbial flora using cultured saliva and oral swabs from subjects with oscc and healthy controls .
the culture plates were incubated at 37c for 48 h , after which the bacterial growth was analyzed .
they concluded from their study that the median number of colony forming units ( cfus)/ml at the carcinoma site were significantly greater than that at the contralateral healthy mucosa .
similarly , in the saliva of carcinoma subjects , the median number of cfus / ml were significantly greater than in the saliva of healthy controls .
( 2014 ) conducted a clinical study to identify the bacterial spectra on the surface of oscc in comparison with the oral mucosa of patients with a higher risk to emerge an oscc and control group to determine their susceptibility to various common antibiotics .
they concluded from their study that the prominent pathogens of the normal healthy oral mucosa were aerobes .
the ratio between aerobes and anaerobes was 2:1 , balanced in risk patients and inverted in the oscc group .
it has been reported that the majority of cases of head and neck cancer can be related to tobacco use and heavy alcohol consumption .
other possible risk factors include viral infections , poor oral hygiene and infection with candida species .
the latter microorganisms are associated with some forms of leukoplakic lesions , the presence of which has long been recognized as an independent risk factor for carcinoma .
the involvement of other microorganisms , particularly bacteria , has not been studied to any great extent .
certain glycoconjugates serve as receptors for specific bacteria , and recent reports support the notion that shifts in the colonization of different cancer cells are associated with observed changes in cell surface receptors .
it is now recognized that bacteria bind to and colonize the mucosal surfaces in a highly selective manner via a lock and key mechanism .
adhesins on bacteria bind specifically to complementary receptors on the mucosal surfaces of the host .
these adhesins differ from species to species , leading to specificity in attachment to different surfaces .
studies have shown that even within genera , colonization patterns of individual species may differ markedly ; streptococcus salivarius , for example , preferentially colonized the oral soft tissues and saliva compared with the teeth , while the reverse was true of streptococcus sanguis .
bacterial infections have been linked to malignancies due to their ability to induce chronic inflammation .
there have been increasing data to confirm that bacterial infections rely upon precise interactions between the pathogens and the components of the host cell regulatory systems that are given below .
it has been shown that several bacteria can cause chronic infections or produce toxins that disturb the cell cycle and lead to altered cell growthchronic infections induce cell proliferation and dna replication through activation of mitogen - activated kinase pathways and cyclin d1 and increase the incidence of cell transformation rate of tumor development through increased rate of genetic mutationseveral infections cause intracellular accumulation of the pathogen , leading to suppression of apoptosis primarily through modulation of the expression of bcl-2 family proteins or by inactivation of retinoblastoma protein , prb .
this strategy provides a niche in which the intracellular pathogen can survive in spite of the attempts of the host immune system to destroy the infected cells by apoptosis .
thus , it allows the partially transformed cells to evade the self - destructive process and progress to a higher level of transformation , ultimately becoming tumorogenicmany pathogenic bacteria causing chronic infection with intracellular access subvert host cell signaling pathways , enhancing the survival of the pathogen .
it has been shown that several bacteria can cause chronic infections or produce toxins that disturb the cell cycle and lead to altered cell growth chronic infections induce cell proliferation and dna replication through activation of mitogen - activated kinase pathways and cyclin d1 and increase the incidence of cell transformation rate of tumor development through increased rate of genetic mutation several infections cause intracellular accumulation of the pathogen , leading to suppression of apoptosis primarily through modulation of the expression of bcl-2 family proteins or by inactivation of retinoblastoma protein , prb .
this strategy provides a niche in which the intracellular pathogen can survive in spite of the attempts of the host immune system to destroy the infected cells by apoptosis .
thus , it allows the partially transformed cells to evade the self - destructive process and progress to a higher level of transformation , ultimately becoming tumorogenic many pathogenic bacteria causing chronic infection with intracellular access subvert host cell signaling pathways , enhancing the survival of the pathogen .
the regulation of these signaling factors is central to the development or inhibition of tumor formation .
such infections can mimic some of the gross effects seen in tumorogenesis , and indeed the precancerous lesion formed in such infections can regress with antibiotic treatment and clearance of bacteria .
this is of relevance in the oral cavity , where the preexisting local microflora may facilitate tumourogenesis by converting ethanol into its carcinogenic derivative , acetaldehyde , to levels capable of inducing dna damage , mutagenesis and secondary hyperproliferation of the epithelium .
this is of relevance in the oral cavity , where the preexisting local microflora may facilitate tumourogenesis by converting ethanol into its carcinogenic derivative , acetaldehyde , to levels capable of inducing dna damage , mutagenesis and secondary hyperproliferation of the epithelium . also , this is evidential from the increased levels of microbial acetaldehyde production in heavy drinkers and smokers , supporting this concept .
microbial carcinogenesis may also involve nitrosation , in which microbial cells catalyze the formation of n - nitroso compounds from the precursor 's nitrite and amines , amides or other nitrosatable compounds .
several species of bacteria encompass strains capable of catalyzing nitrosation , in particular , escherichia coli also , yeasts and fungi may include nitrosating organisms .
this particular nitrosamine appears to be a relevant candidate for the cause of carcinoma , not only of the esophagus but also of other mucosal areas such as the oral cavityrecent studies have shown that podoplanin , a transmembrane glycoprotein , is expressed in various normal as well as neoplastic tissues .
butyric acid ( ba ) , an extracellular metabolite from periodontopathic bacteria , plays an important role in the progression of periodontal disease .
ba / sodium butyrate ( nab ) increases podoplanin expression and cell migration in certain oral squamous cell carcinoma ( oscc ) cell lines , suggesting that the progression of periodontal disease may promote the progression of oscc via a podoplanin - dependent pathwaycertain bacterial infections may evade the immune system or stimulate immune responses that contribute to carcinogenic changes through the stimulatory and mutagenic effects of cytokines released by inflammatory cellsthese include reactive oxygen species ( ros ) , interleukin-8 ( il-8 ) , cyclooxygenase-2 ( cox-2 ) , reactive oxygen species ( ros ) and nitric oxide ( no ) .
microbial carcinogenesis may also involve nitrosation , in which microbial cells catalyze the formation of n - nitroso compounds from the precursor 's nitrite and amines , amides or other nitrosatable compounds .
several species of bacteria encompass strains capable of catalyzing nitrosation , in particular , escherichia coli also , yeasts and fungi may include nitrosating organisms .
this particular nitrosamine appears to be a relevant candidate for the cause of carcinoma , not only of the esophagus but also of other mucosal areas such as the oral cavity recent studies have shown that podoplanin , a transmembrane glycoprotein , is expressed in various normal as well as neoplastic tissues .
butyric acid ( ba ) , an extracellular metabolite from periodontopathic bacteria , plays an important role in the progression of periodontal disease .
ba / sodium butyrate ( nab ) increases podoplanin expression and cell migration in certain oral squamous cell carcinoma ( oscc ) cell lines , suggesting that the progression of periodontal disease may promote the progression of oscc via a podoplanin - dependent pathway certain bacterial infections may evade the immune system or stimulate immune responses that contribute to carcinogenic changes through the stimulatory and mutagenic effects of cytokines released by inflammatory cells these include reactive oxygen species ( ros ) , interleukin-8 ( il-8 ) , cyclooxygenase-2 ( cox-2 ) , reactive oxygen species ( ros ) and nitric oxide ( no ) .
chronic stimulation of these substances along with environmental factors such as smoking or a susceptible host appears to contribute significantly to carcinogenesis .
there is indeed a delicate balance between the microbial flora and our immune system , which allows the microbial flora to live as a commensal organism with us .
but , when disease occurs , these microbial flora become aggressive , giving rise to a host of diseases , some of which are inflammatory , while others are degenerative , cancerous or transitory .
studies reveal that , relative to the contiguous healthy oral mucosa , the human oral carcinoma surface biofilms harbored significantly increased levels of both aerobes and anaerobes .
many cancer centers have reported an increase in quinolone - resistant bacteria ( primarily escherichia coli and pseudomonas aeruginosa ) in patients receiving quinolone prophylaxis .
high levels of colonization of oscc by facultative oral streptococci were observed in the saliva of oscc subjects ( sasaki et al . , 1998 ; sakamoto et al . , 1999 ; tateda et al . , 2000 ; shiga et al . , 2001 ) .
more recently , viable bacteria have been isolated from both superficial and deep portions of the oscc ( hooper et al . , 2006 ; hooper et al . , 2007 ) ,
the role of bacteria in the development of oral cancer has not been delineated , but the persistent presence of bacteria at tumor sites in the oral cavity raises intriguing questions about the role of bacteria in the progression of oscc .
unfortunately , most of such studies to date have included only cultured oral bacterial species , using classical cloning and sequencing approaches ( nagy et al .
, 2005 ; hong et al . , 2006 ) . to establish the association of oral bacteria in the progression of oscc , the complete bacterial profile ( cultured and uncultured ) in the oral cavity of oscc subjects needs to be first determined .
, no large differences were observed for the biofilm flora at the tumor and control sites when the distributions of aerobic species were investigated .
almost similar species were found with the same frequency at both sites ( both tumor and normal sites ) , with the exceptions of serratia liquefaciens , klebsiella pneumoniae and citrobacter freundii from the gram negative species and streptococcus j - haemolyticus and enterococcus faecalis from the gram positive bacteria , which were present more frequently at the tumor sites .
anaerobic bacteria with known pathogenic features , such as actinomyces , clostridium , fusobacterium , prevotella , porphyromonas and members of the bacteroides ureolyticuslgracilis group , were involved in the biofilm formation on the tumor surface , while they were found only occasionally on the healthy mucosa surface of the same patient .
veillonella , a known member of the normal oral flora , was also isolated from twice as many lesion sites as control sites ( 18 versus nine ) .
( 2005 ) reported that several species detected in the nontumoros control tissue were not detected in the tumor tissues , and vice versa .
for instance , exiguobacterium oxidotolerans , prevotella melaninogenica , staphylococcus aureus , veillonella parvula and species of bacteria and micrococcus were isolated only from tumoros specimens and not at all from nontumoros ones .
conversely , moraxella osloensis , prevotella veroralis and species of actinomyces were grown only from nontumoros tissues .
this could indicate that while bacteria are present within all the oral mucosal tissues , there are potentially significant differences between the microfloras within tumoros compared with nontumoros mucosae . in many studies
, it was noticed that smoking and alcohol consumption were commonly associated with carcinoma of the palate , while that of chewing tobacco was commonly associated with carcinoma of the alveolus and buccal mucosa .
it has been stated that alcohol is not carcinogenic , but there is increasing evidence that a major part of the tumor - promoting action of alcohol might be mediated via its first , toxic and carcinogenic metabolite , acetaldehyde .
acetaldehyde is produced from ethanol in the epithelia by mucosal alcohol dehydrogenases , but much higher levels are derived from microbial oxidation of ethanol by the oral microbial flora .
thus , subjects consuming alcohol are at increased risk of developing cancer because of this synergistic action .
gram positive bacteria and yeasts are associated with higher acetaldehyde production , which could be a biologic explanation for the observed synergistic carcinogenic action of alcohol and smoking on upper gastrointestinal tract cancer .
this may open a new microbiologic approach to the pathogenesis of the cancer of the oral cavity and upper gastrointestinal tract .
streptococcus intermedius , prevotella , capnocytophaga and candida albicans were isolated in increased numbers at carcinoma sites .
( 2005 ) assessed the frequency of streptococcus anginosus infection in oral cancer tissues and investigated its infection route .
streptococcus anginosus dna was frequently detected in squamous cell carcinoma ( 19/42 ) , but not in other types of cancer ( lymphoma and rhabdomyosarcoma ) or leukoplakia samples .
a subject - based analysis revealed that streptococcus anginosus was solely detected in dental plaque and not in saliva from all 19 streptococcus anginosus - positive squamous cell carcinoma cases .
further , the genotype of streptococcus anginosus isolated from cancer tissue was identical to that from dental plaque of the same patients .
they concluded that infection of streptococcus anginosus could occur frequently in oscc and that dental plaque could be a dominant reservoir of the streptococcus anginosus bacteria . according to a study by mager et al .
( 2005 ) , devlin pm investigated whether the salivary counts of 40 common oral bacteria in subjects with an oscc lesion would differ from those found in cancer - free ( oscc - free ) controls .
unstimulated saliva samples were collected from 229 oscc - free and 45 oscc subjects and evaluated for their content of 40 common oral bacteria using checkerboard dna dna hybridization .
they concluded that high salivary counts of capnocytophaga gingivalis , prevotella melaninogenica and streptococcus mitis may be diagnostic indicators of oscc . in a review , mager et al .
( 2006 ) concluded that certain bacterial infections may evade the immune system or stimulate immune responses that contribute to carcinogenic changes through the stimulatory and mutagenic effects of cytokines released by inflammatory cells .
bacterial toxins can kill cells or , at reduced levels , alter cellular processes that control proliferation , apoptosis and differentiation .
these alterations are associated with carcinogenesis and may either stimulate cellular aberrations or inhibit normal cell controls . in 2006 , hooper et al .
conducted a study with the primary objective to identify any bacterial species within the oscc tissue using a standard microbiological culture approach . at the time of surgery
, a 1 cm portion of tissue was harvested from deep within the tumor mass using a fresh blade for each cut .
notably , some species were isolated only from either the tumoros or the nontumoros tissue type , indicating a degree of restriction .
successful surface decontamination of the specimens indicates that the bacteria detected were from within the tissue .
hooper et al . in 2007 conducted a study where , in order to characterize the bacterial microbiota present within the oral cancerous lesions , tumoros and nontumoros mucosal tissue specimens ( approximately 1 cm ) were harvested from 10 oscc patients at the time of surgery .
bacteria were visualized within sections of the oscc by performing fluorescent in situ hybridization with the universal oligonucleotide probe , eub338 .
this was then used as a template for polymerase chain reaction ( pcr ) with three sets of primers , targeting the 16s rrna genes of spirochaetes , bacteroidetes and the domain bacteria .
differences between the composition of the microbiotas within the tumoros and nontumoros mucosae were apparent , possibly indicating selective growth of bacteria within the carcinoma tissue .
whether the presence of these bacteria within the mucosa has any bearing on the carcinogenic process is a concept worthy of further investigation . in a case
( 2009 ) evaluated the role of helicobacter pylori in the etiology of mucosal inflammation , a condition that compounds the morbid state associated with oral submucous fibrosis .
a rapid urease test ( rut ) of plaque samples was performed to estimate the helicobacter pylori bacterial load .
they concluded that the contribution of helicobacter pylori in dental plaque to mucosal inflammation and periodontal disease was significant .
logistic regression analysis showed gastrointestinal disease and poor oral hygiene as being the greatest risk factors for bacterial colonization , irrespective of the subject groups .
a positive correlation exists between rut reactivity and the frequency of mucosal inflammation . in 2009 ,
fernando and jayakumar et al . undertook a study to determine the presence of helicobacter pylori in the oral lesions of 30 oral cancer patients and to determine the presence of igg antibodies to helicobacter pylori in oral cancer patients who are betel chewers , nonbetel chewers , healthy betel chewers and healthy nonbetel chewers , and to compare the presence of helicobacter pylori in these four groups .
one hundred and seventy - three subjects , of whom 53 were patients presenting with oral cancer to the cancer institute maharagama , 60 were healthy betel chewers and 60 were healthy nonbetel chewers from the religious and welfare service centre maharagama , were tested for helicobacter pylori by serology .
thirty oral biopsies from oral cancer patients were cultured under microaerophilic conditions to isolate helicobacter pylori . of the 53 oral cancer patients , 44 were betel chewers . among the 53 oral cancer patients examined , 10 of 44 ( 22.7% ) patients who are betel chewers and four of nine ( 44.4% ) patients who are nonbetel chewers were detected to be positive for igg antibody against helicobacter pylori . in the healthy group ( betel chewers and nonbetel chewers ) , 10/60 ( 16.7% ) of the healthy betel chewers tested positive for helicobacter pylori by serology .
fourteen ( 26.4% ) of the oral cancer patients tested positive for helicobacter pylori by serology ,
the presence of helicobacter pylori in betel chewers ( with or without cancer ) compared with nonbetel chewers was statistically significant ( chi - square test , p < 0.05 ) .
the use of tobacco and areca nut in betel chewers was significant with the presence of helicobacter pylori ( p < 0.05 ) .
the oral cavity has been considered a potential reservoir for helicobacter pylori , from where the organism causes recurrent gastric infections .
they conclude from their study that there is a significantly higher proportion of helicobacter pylori in betel chewers compared with nonbetel chewers but not between oral cancer patients compared with patients without oral cancer .
hence , betel chewing may predispose to colonization with helicobacter pylori in the digestive tract through swallowing the quid or during betel chewing .
jukka in 2010 concluded in a review that microbial populations on the oral mucosa differ between healthy and malignant sites and certain oral bacterial species have been linked with malignancies , but the evidence is still weak in this respect .
nevertheless , oral microorganisms inevitably up - regulate cytokines and other inflammatory mediators that affect the complex metabolic pathways , and may thus be involved in carcinogenesis .
chocolatewala et al . in 2010 concluded in a review that studies have shown diversity of isolated bacterial taxa between the oral cancer tissue specimens and the control , with exiguobacterium oxidotolerans , pseudomonas melaninogenica , staphylococcus aureus and veillonella parvula being specific for tumorigenic tissues .
streptococcus anginosus , commonly linked with esophageal and pharyngeal cancers , is not of significance in oral cancers .
similarly , significant salivary specificity is noted for three bacteria , namely candida gingivalis , pseudomonas melaninogenica and streptococcous mitis , in oral cancer patients , making these species salivary markers for the early detection of oral cancers and thus improving the survival rate significantly .
pushalkar et al . in 2011 concluded that the most prevalent genera in the oscc library were streptococcus , gemella , rothia , peptostreptococcus , porphyromonas and lactobacillus . to understand the role of bacteria in the development of oral cancer ,
the first step is to identify both cultured and uncultured organisms in the saliva as these organisms have the potential to cause inflammation that may support oscc progression .
anand et al . in 2011 conducted a hospital - based , case control study on 20 patients with newly diagnosed oral cancer and 20 healthy controls without any cancer to evaluate the associations between helicobacter pylori infection and oral cancer using culture and 16srna pcr technique for bacterial identification .
helicobacter pylori was identified by culture in one control ( 1/20 ) and three cases ( 3/20 ) .
the presence of helicobacter pylori was confirmed by pcr of the cultured organism and various biochemical tests .
however , the results of the pilot study support the association of helicobacter pylori with oral cancers , although the odds ratio is not statistically significant and the strength of the association suggests a possible association with high - risk behavior in oral cancer cases .
furthermore , it was found that helicobacter pylori dna was not unique to cancerous oral tissue as pcr from controls was also positive for two of 20 controls .
although a cause - and - effect relationship can not be inferred from this study , our findings can serve as a pilot study for further studies of helicobacter pylori .
( 2014 ) assessed the microbial flora using cultured saliva and oral swabs from subjects with oscc and healthy controls .
the culture plates were incubated at 37c for 48 h , after which the bacterial growth was analyzed .
they concluded from their study that the median number of colony forming units ( cfus)/ml at the carcinoma site were significantly greater than that at the contralateral healthy mucosa .
similarly , in the saliva of carcinoma subjects , the median number of cfus / ml were significantly greater than in the saliva of healthy controls .
( 2014 ) conducted a clinical study to identify the bacterial spectra on the surface of oscc in comparison with the oral mucosa of patients with a higher risk to emerge an oscc and control group to determine their susceptibility to various common antibiotics .
they concluded from their study that the prominent pathogens of the normal healthy oral mucosa were aerobes .
the ratio between aerobes and anaerobes was 2:1 , balanced in risk patients and inverted in the oscc group .
there is increasing evidence that some pathogenic bacteria can contribute to specific stages of cancer development .
in particular , chronic infections triggered by bacteria can facilitate tumor initiation or progression because , during the course of infection , normal cell functions can undergo the control of factors released by the pathogen .
these bacterial factors , namely virulence factors , can directly manipulate the host regulatory pathways and the inflammatory reaction .
the challenge of finding and understanding the true associations between bacterial infections and human cancers is indeed great .
many of the bacterial infections that promote oncogenesis , by disrupting the oral mucosal surface , allow bacterial invasion and perhaps serve as a point of entry to the regional lymph nodes .
this indicates that although the bacterial biota were commensals of the oral cavity , they may become pathogenic when their balance is disturbed . unlike viral infections , bacterial infections
are typically curable , and the prospect of antibiotic treatments to prevent , alleviate or cure cancers is obviously alluring .
vaccination against etiologic pathogens to prevent infection and thus eliminate the risk of cancer is yet another hopeful prospect for researchers .
Output:
| oral cancer appears to be increasing in incidence , and mortality has hardly improved over the past 25 years .
better understanding of the etiopathogenesis should lead to more accurate and earlier diagnosis and more effective treatments with fewer adverse effects . despite increasing interest in the possible relationships between bacteria and the different stages of cancer development
, the association of bacteria with cancer of the oral cavity has yet to be adequately examined .
different bacteria have been proposed to induce carcinogenesis , either through induction of chronic inflammation or by interference , either directly or indirectly , with eukaryotic cell cycle and signaling pathways or by metabolism of potentially carcinogenic substances like acetaldehyde , causing mutagenesis .
this review presents the possible carcinogenesis pathway involved in bacterial carcinogenesis , commonly implicated bacteria in oral carcinogenesis and their role in cancer therapeutics as well . |
PubmedSumm118615 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: trace elements ( te ) are of growing interest in medical studies , with the majority of publications focused on element deficiencies and related syndromes .
advancements in biochemical knowledge are leading to a better understanding of the roles of various elements in metabolic processes and tissue accumulation .
the definition of te in biology is somewhat flexible , with the term used to refer to dietary minerals needed in small quantities for proper physiology and development of an organism ( including active elements of metabolic processes , such as copper , magnesium , and zinc ) as well as elements that accumulate due to environmental pollution ( lead and cadmium ) .
there is not yet a comprehensive biological definition or complete list of trace elements found in humans . te content
is most easily analyzed in bone tissue because it is the trace elements repository , reflecting the turnover for the whole organism . te content
can also be examined in more unstable compartments , such as serum , urine , or cerebrospinal fluid , which show more rapid changes secondary to exposure or specific response of the organism .
one of the most highly specific tissues is human intervertebral disc ( ivd ) . in the first decade of life , this tissue becomes avascular , such that all metabolism relies on passive nutrient transport through the end - plates , which are cartilage - resembling tissue that act as barriers , separating ivd from the bone of the vertebrae .
confined in the center of the ivd , the nucleus pulposus environment is rich in lactic acid and has a lower oxygen concentration and higher ph compared to other tissues .
these conditions result in a low cell concentration , with slow metabolism and abundant extracellular matrix ( ecm )
the causes of ddd are complex and not fully understood , but appear to mainly involve aging , and genetic or environmental factors .
the mainstream concept of degeneration assumes disproportionate levels of anabolic and catabolic activity in the ecm .
these processes involve enzymes such as cathepsins , aggrecanases , and matrix metalloproteinases ( mmps ) .
mmps are zinc - dependent endopeptidases that are active in protein degradation . other te are also involved in enzyme activity for example , copper is present in cytochrome oxidase or ceruloplasmin or are involved in collagen synthesis and connective tissue development .
evaluated post - mortem ca , p , s , mg , and na concentrations .
minami et al . analyzed platinum levels in bone and ivd from cisplatin - treated ovarian cancer patients , and found that intradiscal metal accumulation after exposure exceeded bone accumulation by up to 4.3-fold .
other observations have also shown that in some cases te concentrations can be higher in disc or bone tissue than in internal organs , such as liver and kidneys . the present study aimed to analyze the selected te profile ( al , cd , pb , cu , ni , mo , mg , and zn ) in human degenerated intervertebral disc tissue , and to compare the concentrations with those found in other tissues .
the study material included 30 intervertebral discs obtained from 22 patients undergoing surgical discectomy or spine fusion due to degenerative disc disease .
twelve specimens were from the cervical spines of 6 patients , and 18 specimens were harvested from the lumbar spines of 16 patients .
preoperative magnetic resonance images were used to evaluate the degeneration status of the operated disc according to pfirrmann score .
atomic absorption spectrometry ( aas ) was used to determine the concentrations of the trace elements al , cd , pb , cu , ni , mo , mg , and zn , which were calculated using the dry weight ( dw ) of the disc .
the use of tissue in this study was approved by the appropriate bioethics committee , and written consent was obtained from all patients .
the mean age of the patients at the time of operation was 47.6 ( range , 2864 years ) .
all patients were interviewed using a questionnaire to collect data on demography , health status , and occupational heavy metals exposure .
none of the patients had knowledge of being inadvertently exposed to heavy metal pollution . based on postal zip codes , we obtained information regarding each patient s places of residence and work over the last 5 years .
places of residence and employment were stratified according to population count as follows : > 500 k , 200499 k , 100199 k , 2099 k , < 20 k , and village inhabitants .
first , the frozen intervertebral disc samples were freeze - dried using a lyovac lyophilizer gt2e ( steris , germany ) for 24 hours .
the samples were weighed after drying . then 65% nitric acid ( merck , germany ) was added to obtain a dilution factor ( df ) of 10 , with amounts in the ranges of 0.20.6 g of sample and 2.06.0 ml of nitric acid .
then the samples were mineralized in a microwave oven ( mars xpress 5 , cem usa ) .
trace element concentrations in the mineralized samples were determined using an aas 7000 spectrometer ( shimadzu , japan ) with graphite furnace atomization ( gf - aas ) for al , cu , cd , mo , ni , and pb , or with flame atomization ( f - aas ) for mg and zn . all analyses were run in 3 replicates .
the percent rsd did not exceed 5% for gf - aas analysis , and did not exceed 7% for f - aas analysis .
table 1 presents the basic optimized parameters for the determination of al , cu , cd , mo , ni , pb , zn , and mg using aas .
the results are presented as means and ranges . where applicable , standard deviation ( sd ) was also calculated .
spearman s rank - order correlation analysis was used to determine the relationships among different parameters .
p<0.05 was accepted as indicating statistical significance . when an element was not detected in the sample , the limit of detection ( lod ) value
first , the frozen intervertebral disc samples were freeze - dried using a lyovac lyophilizer gt2e ( steris , germany ) for 24 hours .
the samples were weighed after drying . then 65% nitric acid ( merck , germany )
was added to obtain a dilution factor ( df ) of 10 , with amounts in the ranges of 0.20.6 g of sample and 2.06.0 ml of nitric acid .
then the samples were mineralized in a microwave oven ( mars xpress 5 , cem usa ) .
trace element concentrations in the mineralized samples were determined using an aas 7000 spectrometer ( shimadzu , japan ) with graphite furnace atomization ( gf - aas ) for al , cu , cd , mo , ni , and pb , or with flame atomization ( f - aas ) for mg and zn . all analyses were run in 3 replicates .
the percent rsd did not exceed 5% for gf - aas analysis , and did not exceed 7% for f - aas analysis .
table 1 presents the basic optimized parameters for the determination of al , cu , cd , mo , ni , pb , zn , and mg using aas .
the results are presented as means and ranges . where applicable , standard deviation ( sd ) was also calculated .
spearman s rank - order correlation analysis was used to determine the relationships among different parameters .
p<0.05 was accepted as indicating statistical significance . when an element was not detected in the sample , the limit of detection ( lod ) value
the elements al , pb , cu , mg , and zn were detected in every tested sample .
ni was detected in 97% of samples , mo in 83% , and cd in 57% ( table 2 ) .
the concentrations of mg , zn , and cu were 1 order of magnitude higher than the concentrations of the other examined elements ( mgkg dw vs. gkg dw ) .
the measured concentrations were as follows ( range values with mean value and standard deviation , respectively ) : al , mean of 663.71 , range of 165.71271 , sd of 288.84 ( in gkg dw ) ; cu , mean of 3.41 , range of 0.9723.64 , sd of 4.045 ( in mgkg dw ) ; mg , mean of 800.1 , range of 182.62132 , sd of 525.5 ( in mgkg dw ) ; zn , mean of 39.60 , range of 10.56184.5 , sd of 35.95 ( in mgkg dw ) ; pb , mean of 8.435 , range of 0.56224.76 , sd of 5.596 ( in gkg dw ) ; cd , mean of 8.435 , range of 0.56224.76 ( in gkg dw ) ; ni mean of 251.38 , range of 25.48444.2 ( in gkg dw ) ; and mo , mean of 54.33 , range of 20.02143.2 ( in gkg dw ) ( table 2 ) . among the elements that were found in only some of the tested samples , the lod values were :
correlation analysis showed significant positive correlation of pb concentration with age ( table 3 ) .
ni concentration showed a weak positive correlation with the population size of the place of residence .
a strong positive correlation was observed between the pair mg / zn , both of which also showed a positive correlation with the non - essential element al and the toxic element pb . there was also a significant positive correlation between al and pb .
our present analysis detected al , pb , cu , mg , and zn in all tested samples .
of these 5 elements , cu , mg , and zn are considered essential in human metabolism , pb is considered non - essential and toxic , and the role of al is not yet fully understood .
the other studied elements were only found in some of the tested samples . of these , cd is not essential and is considered toxic , but mo and ni are considered potentially essential .
the present study had possible methodological flaws ; however , considering the differences between lod and mean levels in the rest of the samples , we can likely regard cd , mo , and ni as non - essential in ivd metabolism and as unrelated to degenerative changes .
except for pb , the majority of non - essential elements tend to concentrate in the tissue up to some critical point , and once this threshold is exceeded , the element is excreted through a variety of methods . for some te
, the accumulation capacity has only been determined for bone tissue ; thus , complete analysis regarding bioaccumulation was not possible in our present study .
investigated the elements abundantly present in ivd tissue , but their report did not include degeneration criteria . due to the lack of relevant data from this particular biological compartment , here , we primarily compare our present findings to previous results from other tissues the most relevant being cartilage and tendons , due to their metabolism , morphology , and biomechanical role .
magnesium content has been reported for a variety of tissues , including intervertebral disc and temporomandibular joint disc ( tmjd ) [ 1315 ] .
tohno el al reported the average mg content of ivd to be 1.196 mgg ( range , 0.62.2 mgg ) from a study of 9 specimens that were acquired post - mortem with no definition of degeneration stage .
our present results showed a lower mean mg concentration of 800.1 mgkg , with a range of 182.62132 mgkg .
this discrepancy could be due to the different methods of tissue acquisition between the 2 studies , and our present results may be grounds to question the use of cadavers as a control group . in another study of cadavers , takano el al .
reported the average mg concentration in tmjd , which was substantially lower than our present results ( mean value 524.74 mgkg
vs. 800.1 mgkg dw ) , and showed a narrower concentration range ( 393.4764.9 mgkg dw ) .
another study shows mg concentrations of 445 mgkg in cervical spine posterior longitudinal ligaments ( pll ) , which are lower than those presently found in ivd and comparable to concentrations reported in tmjd . the standard deviation reported for cervical spine pll mg concentrations ( 161 mgkg ) was smaller than that in our study ( 525.5 mgkg ) .
the mg concentration in bone has been reported as 1792.9 mgkg , which is more than 2 times higher than that found for ivd .
magnesium has many biological functions , and is the fourth most abundant cation in the body and the second most abundant intracellular cation .
the majority of mg ions are found in bone and muscle , with up to 60% of magnesium located within the bone , where it most probably forms the hydroxyapatite surface . in cases of deficiency ,
mg from bone can be readily exchanged with serum , although this exchangeable form can decline with increasing age .
our results showed that mg concentrations in ivd of living patients with ddd were higher than those in ligamentous tissue and tmjd , and smaller than the concentrations found in cadaver ivd .
the difference in mg concentration between bone and ivd tissues was less pronounced than we expected based on the cellularity of each tissue .
since the cellularity of bone is substantially higher than that of ivd , we can conclude that mg in ivd is mainly extracellular .
the intracellular range of mg concentration is maintained within strict limits , except under severe hypoxic stress or magnesium depletion . up to 5% of intracellular magnesium
is present in the form of free ions , with the rest bound to ionic compounds , such as atp , adp , citrate , proteins , rna , and dna , or stored in the mitochondria and endoplasmic reticulum .
it has been shown that mg can decrease mmp secretion to the extracellular matrix after stimulation with growth factors .
migration of cells , such as macrophages and fibroblasts , in the early stages of skin wound repair is associated with mg increase .
mg is connected with migratory phenotype activation and maintenance through modifications of integrins and e - cadherin .
it has further been observed that magnesium deficiency results in loss of replicative capacity , and increases the expression of senescence - associated biomarkers in human fibroblasts .
overall , mg is predominantly located in ecm and its activity is related to repair process , which is supported by the presently observed higher concentration in ddd tissue compared to in ligaments .
cu concentration is best documented in bone tissue , with average reported concentrations of 0.62 mgkg dw and 0.8 mgkg dw .
similar cu concentrations have also been found in cartilage , with an average value of 0.79 mgkg dw and range of 0.201.78 mgkg .
our results showed that the copper concentration in ivd ( mean 3.41 , range 0.9723.64 mgkg dw ) was more than 3 times higher than those previously observed in bone and cartilage .
copper and zinc are both predominantly associated with animal proteins , and are known for their antagonism , in that they tend to nullify each other s actions .
copper is a redox - active metal that is predominantly used by organisms living in oxygen - rich environments , and that fluctuates between the oxidized ( cu ) and reduced ( cu ) states .
it is also a compound of the xiap protein , which acts as an apoptosis inhibitor .
cu ions are a key element of cytochrome oxidase , which is responsible for mitochondrial phosphorylation and atp production .
the integral membrane protein ctr1 functions as a major copper importer at the plasma membrane .
recent findings in yeast and mammals strongly suggest that ctr1 facilitates uptake of the metal - based anti - neoplastic drug cisplatin .
this may explain the higher pt concentration in cisplatin - treated patients reported by minami et al . .
there may be a connection between high cu concentration , low oxygen environment , and the warburg effect .
the warburg effect includes a down - regulation of cell respiratory capacity that is observed in many cancer cell types , with a corresponding shift to glycolysis for cell energy generation .
this process can be related to p53 protein mutation , which is a common genetic change found in a broad range of cancer cells .
p53-inactive mutation cells show significantly reduced oxygen consumption , while generating increased levels of lactate .
it has been proposed that a link between p53 and sco2 gene expression levels may hamper copper acquisition and promotion of the warburg effect .
the high lactic acid concentration due to glycolysis is the natural environment for ivd tissue .
it is possible that glycolysis may be related to cu concentration other than in the warburg effect , which , in turn , may also be related to the p53 gene .
however , ivd tissue is virtually free from mutagenesis , except for chordoma that arises from the remnants of the notochord , suggesting a low risk of p53 mutations in ivd cells .
another hypothesis is that higher cu concentration may be a tissue - specific countermeasure to primary oxygen deficiency or promotion of oxygen - based energy acquisition
. a possible third explanation of higher cu concentration in disc tissue may relate to the element s role in the repair process .
higher copper concentrations have been observed in wounds during the healing process , and the element has been observed to induce vascular endothelial growth factor expression .
however , this explanation is less likely because the process is bound with vascular ingrowth , which is not observed in disc tissue except for outer parts of the annulus fibrosus .
the presently determined intervertebral disc zinc concentration ( 39.9 mgkg dw ) was similar to the levels in pll ( 36 mgkg dw ) reported by kumai et al . .
on the other hand , the presently reported ivd concentrations are less than half that of the average concentrations reported in cartilage ( 88.3 mgkg ; range , 54.3163.8 mgkg dw ) and bone ( 84.58 mgkg ; sd 17.68 mgkg ) .
zn plays a well - recognized role in the immune system , is an antioxidant , and has anti - inflammatory actions .
zinc - deficient cells display decreased gene expressions of interleukin-2 and il-2 receptor alpha , suggesting that immune reaction would be less likely during the disc degeneration process .
it also stabilizes the molecular structure of cellular membranes and organelles , contributing to cell and organ integrity .
mmps are zn - dependent compounds involved in ecm turnover , and we thus expected zn concentration to be higher in ivd than in ligaments .
the similar levels of zn in ligaments and ivd raise questions regarding to what degree zn level reflects the mmp concentration and the timing of mmp activation in ivd degenerative processes .
the strong correlation between zn and mg confirms their major metabolic role in ivd tissue .
this correlation was also observed in bone tissue of the cracow , poland population ( correlation , 0.68 ) by jurkiewicz et al . .
aluminum is the third most common element on earth , but is not considered essential in humans .
aluminum cookware is considered safe , since only uncoated cookware can lead to leaching of particles into food .
although its role is not entirely known , several studies have shown its influence on neurodegenerative disorders , including alzheimer s disease , and brain tissue is considered the sink for systemic aluminum .
our present data can not exclude a metabolic role of the element , or the possibility that it plays a role in degeneration induction or the process itself .
the levels observed in our study were smaller than reference values , suggesting that al content is environment - related and depends on end - plate permeability .
lead accumulates in bone , and is thereafter difficult to excrete and is retained by the tissue , such that its concentration tends to increase over time .
the pb accumulation presently observed in ivd resembles that in bone , as pb was the only element that was positively correlated with age .
compared to that in ivd , the pb concentration in bone is up to 2 times higher , with an average of 1.35 mgkg dw . the cartilage pb concentration is lower , with an average of 0.41 mgkg and range of 0.210.65 mgkg , which is comparable to our results in ivd tissue .
viewing cartilage as a reference , we may conclude that pb accumulation is not related to end - plate permeability , in contrast to al .
compared to the presently determined cd concentration in ivd ( 8.4 gkg dw ) , the concentration in bone is reportedly up to 3 times higher ( 30 gkg dw ) .
reported a slightly lower cd concentration in bone tissue ( average , 22 gkg ; range , 1334 gkg ) . in a population
that is occupationally exposed to cd , the bone concentration can be higher , ranging from 0.111.2 mgkg dw .
cartilage cd concentrations are congruous with levels observed in bone ( average , 0.031 mgkg ; range , 0.0010.151 mgkg dw ) .
interestingly , in our study of ivd , cadmium was detected in only 57% of the samples .
the lower concentration of this element in ivd compared to cartilage , and its detection in only some of the tested samples , suggest that the end - plate acts as a selective barrier in cd transport .
nickel is predominantly associated with vegetable food sources , and has no potential biological activity in human metabolism .
brodziak et al . reported a mean ni concentration in bone of 4.82 mgkg ( sd , 10.74 mgkg ; range , 0.0371.49 mgkg ) .
the same study found a similar cartilage content ( mean , 4.40 mgkg ; sd , 7.38 mgkg ) , and a lower concentration in the joint capsule ( mean , 1.38 mgkg ; sd , 2.47 mgkg ) .
the ni concentration in ivd found in our study ( mean , 251.38 gkg ; range , 25.48444.2 gkg ) was only 18% of the previously reported concentration in joint capsule and only 5% of the bone concentration .
although ni presence was confirmed in 97% of tested samples , the results suggest impaired transport of this element into the disc . like zinc and copper , molybdenum
mo concentration in human tissues ranges from 1 to 400 gkg , with the skeletal concentration being in the upper part of this range . in our study , the mean mo concentration in ivd was 54.33 gkg dw , which is more than half of the reference value from the literature ( 75 gkg ) .
magnesium content has been reported for a variety of tissues , including intervertebral disc and temporomandibular joint disc ( tmjd ) [ 1315 ] .
tohno el al reported the average mg content of ivd to be 1.196 mgg ( range , 0.62.2 mgg ) from a study of 9 specimens that were acquired post - mortem with no definition of degeneration stage .
our present results showed a lower mean mg concentration of 800.1 mgkg , with a range of 182.62132 mgkg .
this discrepancy could be due to the different methods of tissue acquisition between the 2 studies , and our present results may be grounds to question the use of cadavers as a control group . in another study of cadavers , takano el al . reported the average mg concentration in tmjd , which was substantially lower than our present results ( mean value 524.74 mgkg
vs. 800.1 mgkg dw ) , and showed a narrower concentration range ( 393.4764.9 mgkg dw ) .
another study shows mg concentrations of 445 mgkg in cervical spine posterior longitudinal ligaments ( pll ) , which are lower than those presently found in ivd and comparable to concentrations reported in tmjd . the standard deviation reported for cervical spine pll mg concentrations ( 161 mgkg ) was smaller than that in our study ( 525.5 mgkg ) .
the mg concentration in bone has been reported as 1792.9 mgkg , which is more than 2 times higher than that found for ivd .
magnesium has many biological functions , and is the fourth most abundant cation in the body and the second most abundant intracellular cation .
the majority of mg ions are found in bone and muscle , with up to 60% of magnesium located within the bone , where it most probably forms the hydroxyapatite surface . in cases of deficiency ,
mg from bone can be readily exchanged with serum , although this exchangeable form can decline with increasing age .
our results showed that mg concentrations in ivd of living patients with ddd were higher than those in ligamentous tissue and tmjd , and smaller than the concentrations found in cadaver ivd .
the difference in mg concentration between bone and ivd tissues was less pronounced than we expected based on the cellularity of each tissue .
since the cellularity of bone is substantially higher than that of ivd , we can conclude that mg in ivd is mainly extracellular .
the intracellular range of mg concentration is maintained within strict limits , except under severe hypoxic stress or magnesium depletion . up to 5% of intracellular magnesium
is present in the form of free ions , with the rest bound to ionic compounds , such as atp , adp , citrate , proteins , rna , and dna , or stored in the mitochondria and endoplasmic reticulum .
it has been shown that mg can decrease mmp secretion to the extracellular matrix after stimulation with growth factors .
migration of cells , such as macrophages and fibroblasts , in the early stages of skin wound repair is associated with mg increase .
mg is connected with migratory phenotype activation and maintenance through modifications of integrins and e - cadherin .
it has further been observed that magnesium deficiency results in loss of replicative capacity , and increases the expression of senescence - associated biomarkers in human fibroblasts .
overall , mg is predominantly located in ecm and its activity is related to repair process , which is supported by the presently observed higher concentration in ddd tissue compared to in ligaments .
cu concentration is best documented in bone tissue , with average reported concentrations of 0.62 mgkg dw and 0.8 mgkg dw .
similar cu concentrations have also been found in cartilage , with an average value of 0.79 mgkg dw and range of 0.201.78 mgkg .
our results showed that the copper concentration in ivd ( mean 3.41 , range 0.9723.64 mgkg dw ) was more than 3 times higher than those previously observed in bone and cartilage .
copper and zinc are both predominantly associated with animal proteins , and are known for their antagonism , in that they tend to nullify each other s actions .
copper is a redox - active metal that is predominantly used by organisms living in oxygen - rich environments , and that fluctuates between the oxidized ( cu ) and reduced ( cu ) states .
it is also a compound of the xiap protein , which acts as an apoptosis inhibitor .
cu ions are a key element of cytochrome oxidase , which is responsible for mitochondrial phosphorylation and atp production .
the integral membrane protein ctr1 functions as a major copper importer at the plasma membrane .
recent findings in yeast and mammals strongly suggest that ctr1 facilitates uptake of the metal - based anti - neoplastic drug cisplatin .
this may explain the higher pt concentration in cisplatin - treated patients reported by minami et al . .
there may be a connection between high cu concentration , low oxygen environment , and the warburg effect .
the warburg effect includes a down - regulation of cell respiratory capacity that is observed in many cancer cell types , with a corresponding shift to glycolysis for cell energy generation .
this process can be related to p53 protein mutation , which is a common genetic change found in a broad range of cancer cells .
p53-inactive mutation cells show significantly reduced oxygen consumption , while generating increased levels of lactate .
it has been proposed that a link between p53 and sco2 gene expression levels may hamper copper acquisition and promotion of the warburg effect .
the high lactic acid concentration due to glycolysis is the natural environment for ivd tissue .
it is possible that glycolysis may be related to cu concentration other than in the warburg effect , which , in turn , may also be related to the p53 gene .
however , ivd tissue is virtually free from mutagenesis , except for chordoma that arises from the remnants of the notochord , suggesting a low risk of p53 mutations in ivd cells .
another hypothesis is that higher cu concentration may be a tissue - specific countermeasure to primary oxygen deficiency or promotion of oxygen - based energy acquisition .
a possible third explanation of higher cu concentration in disc tissue may relate to the element s role in the repair process .
higher copper concentrations have been observed in wounds during the healing process , and the element has been observed to induce vascular endothelial growth factor expression .
however , this explanation is less likely because the process is bound with vascular ingrowth , which is not observed in disc tissue except for outer parts of the annulus fibrosus .
the presently determined intervertebral disc zinc concentration ( 39.9 mgkg dw ) was similar to the levels in pll ( 36 mgkg dw ) reported by kumai et al . .
on the other hand , the presently reported ivd concentrations are less than half that of the average concentrations reported in cartilage ( 88.3 mgkg ; range , 54.3163.8 mgkg dw ) and bone ( 84.58 mgkg ; sd 17.68 mgkg ) .
zn plays a well - recognized role in the immune system , is an antioxidant , and has anti - inflammatory actions .
zinc - deficient cells display decreased gene expressions of interleukin-2 and il-2 receptor alpha , suggesting that immune reaction would be less likely during the disc degeneration process .
it also stabilizes the molecular structure of cellular membranes and organelles , contributing to cell and organ integrity .
mmps are zn - dependent compounds involved in ecm turnover , and we thus expected zn concentration to be higher in ivd than in ligaments .
the similar levels of zn in ligaments and ivd raise questions regarding to what degree zn level reflects the mmp concentration and the timing of mmp activation in ivd degenerative processes .
the strong correlation between zn and mg confirms their major metabolic role in ivd tissue .
this correlation was also observed in bone tissue of the cracow , poland population ( correlation , 0.68 ) by jurkiewicz et al . .
aluminum is the third most common element on earth , but is not considered essential in humans .
aluminum cookware is considered safe , since only uncoated cookware can lead to leaching of particles into food .
although its role is not entirely known , several studies have shown its influence on neurodegenerative disorders , including alzheimer s disease , and brain tissue is considered the sink for systemic aluminum .
our present data can not exclude a metabolic role of the element , or the possibility that it plays a role in degeneration induction or the process itself .
the levels observed in our study were smaller than reference values , suggesting that al content is environment - related and depends on end - plate permeability .
lead accumulates in bone , and is thereafter difficult to excrete and is retained by the tissue , such that its concentration tends to increase over time .
the pb accumulation presently observed in ivd resembles that in bone , as pb was the only element that was positively correlated with age . compared to that in ivd ,
the pb concentration in bone is up to 2 times higher , with an average of 1.35 mgkg dw . the cartilage pb concentration is lower , with an average of 0.41 mgkg and range of 0.210.65 mgkg , which is comparable to our results in ivd tissue . viewing cartilage as a reference , we may conclude that pb accumulation is not related to end - plate permeability , in contrast to al .
compared to the presently determined cd concentration in ivd ( 8.4 gkg dw ) , the concentration in bone is reportedly up to 3 times higher ( 30 gkg dw ) .
reported a slightly lower cd concentration in bone tissue ( average , 22 gkg ; range , 1334 gkg ) . in a population
that is occupationally exposed to cd , the bone concentration can be higher , ranging from 0.111.2 mgkg dw .
cartilage cd concentrations are congruous with levels observed in bone ( average , 0.031 mgkg ; range , 0.0010.151 mgkg dw ) .
interestingly , in our study of ivd , cadmium was detected in only 57% of the samples .
the lower concentration of this element in ivd compared to cartilage , and its detection in only some of the tested samples , suggest that the end - plate acts as a selective barrier in cd transport .
nickel is predominantly associated with vegetable food sources , and has no potential biological activity in human metabolism .
reported a mean ni concentration in bone of 4.82 mgkg ( sd , 10.74 mgkg ; range , 0.0371.49 mgkg ) .
the same study found a similar cartilage content ( mean , 4.40 mgkg ; sd , 7.38 mgkg ) , and a lower concentration in the joint capsule ( mean , 1.38 mgkg ; sd , 2.47 mgkg ) . the ni concentration in ivd found in our study ( mean , 251.38 gkg ; range , 25.48444.2 gkg ) was only 18% of the previously reported concentration in joint capsule and only 5% of the bone concentration . although ni presence was confirmed in 97% of tested samples , the results suggest impaired transport of this element into the disc .
like zinc and copper , molybdenum is predominantly bound with animal protein , and is related to animal food intake .
mo concentration in human tissues ranges from 1 to 400 gkg , with the skeletal concentration being in the upper part of this range . in our study , the mean mo concentration in ivd was 54.33 gkg dw , which is more than half of the reference value from the literature ( 75 gkg ) .
the present analysis is one of the few to address trace element concentrations in ivd tissue .
the results add to a preliminary picture of the ivd chemical environment , and possible dependencies between te in ivd tissue .
this study showed significant differences between the trace element concentrations in intervertebral disc and in other tissues , especially bone . te concentration
may be influenced by dietary components rich in particular elements , as well as by biogenic factors , such as pregnancy and lactation .
the major consideration in ivd tissue is selective end - plate permeability , which can be suspected in the cases of ni , cd , and al , but not pb . biochemical , environmental , and metabolic functions could also favor the accumulation of some elements in higher quantities , as is the case for cu .
further cross - referencing against other tissues and a better understanding of the biochemistry of the ivd are essential to answer the questions arising in this study .
Output:
| backgroundfew studies have investigated trace elements ( te ) in human intervertebral disc ( ivd ) tissue.trace element presence can have diverse meanings : essential te show the metabolic modalities of the tissue , while environmentally - related te indicate pollution and tissue - specific absorption and accumulation.ivd is a highly specific compartment with impaired communication with adjacent bone .
analysis of te in ivd provides new insights regarding tissue metabolism and ivd communication with other tissues.material/methodsthirty intervertebral discs were acquired from 22 patients during surgical treatment for degenerative disease .
atomic absorption spectrometry was used to evaluate the concentrations of al , cd , pb , cu , ni , mo , mg , and zn.resultsal , pb , cu , mg , and zn were detected in all samples .
pb was significantly positively correlated with age , and ni concentration was weakly correlated with population count in the patient s place of residence .
only cu was observed in higher concentrations in ivd compared to in other tissues .
significant positive correlations were observed between the following pairs : mg / zn , mg / al , mg / pb , zn / al , zn / pb , and al / pb . negative correlations were observed between mg / cd , zn / cd , mg / mo , and mo / pb.conclusionsthis study is one of few to profile the elements in intervertebral discs in patients with degenerative changes .
we report significant differences between trace element concentrations in intervertebral discs compared to in other tissues .
knowledge of the te accumulation pattern is vital for better understanding intervertebral disc nutrition and metabolism . |
PubmedSumm118616 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: an animal s reaction to a sensory stimulus depends on the context in which it is presented . in the cortex ,
even primary sensory areas receive a large number of top - down inputs from higher - order regions , in addition to the thalamic input that directly conveys sensory messages .
these top - down connections are believed to underlie the integration of sensory inputs with nonsensory context .
one case in which a role for top - down cortical connections has been established is attention in the primate visual system .
strong electrical stimulation of the frontal eye fields ( fefs ) produces eye movements to a topographically aligned location in space .
however , weaker electrical stimulation below the threshold for eliciting an overt saccade instead mimics the effects of attention to this location , causing increased behavioral and neuronal responses to stimuli presented there ( moore and armstrong , 2003 ) . in rodents , a robust experimental model of attention has not yet been established . however , there are remarkable parallels between the effects of attention on cortical processing in primates and changes in cortical state that occur with changes in behavioral context in rodents ( harris and thiele , 2011 ) .
cortical states were first described in relation to the sleep cycle . during slow - wave sleep , animals exhibit a synchronized state , characterized by large , slow fluctuations in the spiking and membrane potentials of large neuronal populations . by contrast , the cortex of awake , active , and alert animals exhibits a desynchronized state ( also termed activated state ) in which slow fluctuations are replaced by tonic cortical firing , often together with a higher - frequency gamma oscillation .
recent work has shown that these classical states are in fact points on a continuum .
for example , quietly resting rodents show a moderately synchronized state , with fluctuations in cortical activity that are shallower and faster than classical sleep oscillations . when animals engage in active behaviors such as whisking or running , however , these moderate fluctuations are further reduced ( polack et al . , 2013 ; poulet et al . ,
there are several parallels between the correlates of selective attention in primates and cortical states in rodents .
their effects on local field potential oscillations are similar : when animals pay attention to a particular location in space , low - frequency oscillations are reduced in the aligned region of area v4 , while high - frequency lfps are increased ( fries et al . , 2001 ) . attention and desynchronization
both produce a decrease in trial - to - trial variability and noise correlation of sensory responses ( cohen and maunsell , 2011 ; goard and dan , 2009 ; marguet and harris , 2011 ; mitchell et al . ,
importantly , these effects only occur when attention is directed into the receptive fields of recorded neurons .
this suggests that attention causes an effect similar to desynchronization , occurring locally in the region of visual cortex topographically aligned with the attended location .
moreover , recent results suggest that when attention is directed not to a region of space but to a visual feature , variability and correlation decrease in the population that encodes this feature ( cohen and maunsell , 2011 ) , suggesting that a phenomenon analogous to desynchronization has occurred in a spatially distributed neuronal assembly . the mechanisms of cortical state change have been a subject of investigation for many decades .
the first , espoused by steriade and colleagues , held that cortical states are modulated primarily via the thalamus . in this view , increased cholinergic input to thalamic relay cells leads to increased tonic firing and thus to a steady glutamatergic drive to cortex that causes desynchronization .
the second perspective , espoused by vanderwolf and colleagues , held that cortical state reflected direct neuromodulation of neocortex .
recent research provides support for both mechanisms . in the rodent somatosensory system , whisking causes increased tonic firing in thalamus ; blocking thalamic firing with muscimol reduces the cortical depolarization caused by whisking , whereas stimulating thalamus optogenetically causes cortical desynchronization ( poulet et al . , 2012 ) .
support for direct cortical neuromodulation comes from the ability of locally applied neuromodulatory blockers to reduce the desynchronization caused by electrical stimulation of nucleus basalis or locomotion ( goard and dan , 2009 ; polack et al . ,
if attention does indeed consist of cortical state change occurring at a local level , one might expect the two phenomena to have similar circuit mechanisms .
in particular , given the role of top - down cortical connections in attention , it has been hypothesized that tonic glutamatergic input from higher - order cortex should also cause desynchronization in rodent cortex ( harris and thiele , 2011 ) .
( 2013 ) performed a number of elegant experiments to study the role of top - down connections from vibrissa motor cortex ( vm1 ) to barrel cortex ( s1 ) .
they found that blocking spiking in vm1 using muscimol shifted s1 toward more synchronized states , whereas optogenetically increasing vm1 activity shifted s1 toward more desynchronized states .
importantly , the effects on s1 state did not simply reflect the consequence of these manipulations on behavior .
as might be expected , suppression or activation of vm1 activity caused a corresponding decrease or increase in the probability and amplitude of whisking .
nevertheless , an effect of manipulating vm1 on s1 state was seen even when analyzing data within whisking or nonwhisking periods .
one can thus make an analogy between the effects of stimulating vm1 in rodents and the effects of stimulating fef in primates : while strong enough stimulation of these areas causes an overt movement ( saccade or whisking ) , weaker stimulation may instead produce covert effects on sensory processing in lower cortical areas ( attention or desynchronization ) . to investigate the mechanisms by which vm1 stimulation causes desynchronization of s1 , zagha et al .
current - source density analysis showed that vm1 stimulation produces sinks in layer 1 and layers 5/6 , corresponding to the major termination zones of these cortical feedback axons . by applying varying concentrations of the glutamatergic antagonist cnqx
, they showed that the increase in firing of superficial layer s1 neurons required layer 1 inputs , whereas inputs terminating in deep layers were sufficient for increased firing of layer 5 cells . to investigate whether stimulation of vm1 desynchronizes s1 via a direct pathway , without requiring additional relay stations , they performed additional tests .
optogenetic activation of vm1 could still desynchronize vs1 after suppressing activity in vpm thalamus ; and optical stimulation of vm1 axons in s1 could still activate s1 even when the firing of vm1 somas was blocked to eliminate antidromic signaling .
these data confirm that , in addition to the classical pathways that modulate cortical states , top - down projections are capable of directly desynchronizing sensory cortex ( see figure 1 ) .
previous work has shown that the response to strong , sudden stimuli , such as tone onsets or whisker deflections is robust in both synchronized and desynchronized states ( castro - alamancos , 2004 ; luczak et al . , 2013 ) .
however , more subtle , temporally extended stimuli such as natural movies , sustained tones , or repeated whisker deflections are represented more faithfully by the desynchronized cortex ( goard and dan , 2009 ; luczak et al
one may again make an analogy with attention : strong , sudden stimuli which are capable of eliciting bottom - up
attention are able to drive responses in either state , but faithful representation of weaker stimuli requires top - down attention in the form of cortical desynchronization .
( 2013 ) investigated the effects of vm1-elicited desynchronization on the representation of a sequence of whisker deflections of random amplitudes .
consistent with this view , they found that the representation of low - amplitude whisker deflections was made more reliable by vm1 stimulation , but the representation of large - amplitude deflections was less affected .
this study has provided very important information on the function of top - down connections in rodent cortex , as well as further support for a close relationship between cortical state modulation and selective attention .
first , how specifically can top - down connections modulate sensory cortex in rodents ? in primates , selective attention causes effects analogous to desynchronization in localized areas of cortex and even in anatomically distributed neuronal assemblies ( cohen and maunsell , 2011 ; fries et al .
stimulation of primate fef causes increased sensory responses and reduced variability only in topographically aligned regions of v4 ( moore and armstrong , 2003 ) .
( 2013 ) provide a partial answer to this question by showing that vm1 stimulation causes less desynchronization of visual cortex than of barrel cortex . but
could projections from vm1 to vs1 selectively target a single whisker barrel or a distributed neuronal assembly ?
( 2013 ) s study , together with previous work , shows that there are at least three circuit pathways that can contribute to cortical desynchronization : direct neuromodulation of cortex , increased tonic activity of thalamus , and increased corticocortical input ( see figure 1 ) .
there are reasons to suspect that the space of states is indeed multidimensional , i.e. , that in addition to the common effect of reducing low - frequency fluctuations , different desynchronizing manipulations have diverse effects on cortical processing .
2013 ) showed that strong vm1 stimulation typically increases the firing rates of both of superficial and deep layer neurons .
a similar effect was seen due to running in mouse v1 ( niell and stryker , 2010 ) , but desynchronizing brainstem stimulation ( sakata and harris , 2012 ) , or direct cholinergic manipulation of thalamus ( hirata and castro - alamancos , 2010 ) , causes a desynchronization with suppressed superficial layer firing .
together with other examples ( harris and thiele , 2011 ) , these results suggest that the different pathways mediating cortical desynchronization have nonidentical effects on cortical processing .
given the number of ways that context can affect stimulus perception , one should expect the neural circuits producing nonsensory control of cortex to be highly complex .
Output:
| sensory cortices receive inputs not only from thalamus but also from higher - order cortical regions . here , zagha et al .
( 2013 ) show that motor cortical inputs can switch barrel cortex into a desynchronized state that enables more faithful representation of subtle sensory stimuli . |
PubmedSumm118617 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: in recent years , cases of age estimation in the living individual have become more frequent . for the living ,
the aim is to solve judicial or civil problems concerning age of minors regarding questions of adoption , imputability and pedopornography . for adults , civil issues on pensionable age ( 50 , 55 , 60 , 65 years , depending on the country ) and other similar matters for individuals ( mainly immigrants and refugees ) lacking valid documents of identification .
in children , age determination from teeth is a relatively simple , accurate procedure and is based on the stages of development and eruption of teeth .
however , in adults it is a challenge to medico - legal science . until now
, a multiplicity of methods have been applied to estimate age based on dental tissue and tooth morphology .
radiography being a non - destructive method plays a vital role in forensic dentistry to uncover the hidden facts , which can not be seen by means of physical examination .
radiographic age estimation using teeth rely on developmental stages of teeth especially in children whereas in adults ; the continuous deposition of secondary dentin throughout life depicted by reduction in pulp area can be employed .
the present study was undertaken to assess the chronological age of adults of karnataka aged between 18 and 72 years based on the relationship between age and measurement of the pulp / tooth area ratio of maxillary canine , using panoramic radiographs and a computer - aided drafting program .
the purpose of the present research was to derive a population - specific formula based on cameriere 's method .
subjects and materials : panoramic radiographs of 200 patients of karnataka were analyzed [ table 1 ] based on the following criteria :
patients aged between 18 and 72 yearsthe selected tooth on the panoramic radiograph was the right or left maxillary canine , which had fully erupted into the oral cavitythe root of the canine was fully formed .
patients aged between 18 and 72 years the selected tooth on the panoramic radiograph was the right or left maxillary canine , which had fully erupted into the oral cavity the root of the canine was fully formed .
age and gender distribution of the study groups canines with any pathology , such as , caries or periodontitis or periapical lesions , malaligned canines or rotated canines , canines with any prosthetic fittings and orthodontic appliances , fractured canines , severely attrited canine secondary to parafuntional habits and canines with any developmental anomalies were excluded from the study . ethical clearance and informed consent
panoramic radiographs were digitized using scanner , and images were recorded in a computer file .
radiographic images of canines ( ric ) were processed using a computer - aided drafting program -imagej .
twenty points from each tooth outline and ten points for each pulp outline were identified and used to evaluate tooth and pulp areas .
measurements of the ric , yielded pulp and tooth areas [ figure 1 ] ; tooth , pulp and root lengths [ figure 2 ] ; and pulp and root widths [ figure 3 ] , at three different levels .
all measurements were made without prior information about personal data of the subjects . to test intra and inter observer reproducibility ,
a random sample of forty ric were re - examined after an interval of two weeks .
( a ) measurements of the ric yielded tooth area ; ( b ) measurements of the ric yielded pulp area and pulp and root widths measurements of the ric yielded tooth , pulp and root lengths measurements of the ric yielded pulp and root widths the following morphological variables were recorded : p = pulp / root length ; r = pulp / tooth length ; a = pulp / root width at enamel - cementum junction ( ecj ) level ; c = pulp / root width at mid - root level ; b = pulp / root width at midpoint level between ecj level and mid - root level ; ar = pulp / tooth area ratio .
correlation coefficients were evaluated between age and predictive variables . to obtain an estimate age as a function of the morphological variables and gender of the subjects ,
a multiple linear regression model was developed with first order interactions by selecting those variables that contributed significantly to age estimations using the stepwise selection method .
mean comparison of morphological variables between male and female was carried out by using student 's t - test .
statistical analysis was performed with statistical package for the social sciences software ( spss , version 10.5 ) package .
the following morphological variables were recorded : p = pulp / root length ; r = pulp / tooth length ; a = pulp / root width at enamel - cementum junction ( ecj ) level ; c = pulp / root width at mid - root level ; b = pulp / root width at midpoint level between ecj level and mid - root level ; ar = pulp / tooth area ratio .
correlation coefficients were evaluated between age and predictive variables . to obtain an estimate age as a function of the morphological variables and gender of the subjects ,
a multiple linear regression model was developed with first order interactions by selecting those variables that contributed significantly to age estimations using the stepwise selection method .
mean comparison of morphological variables between male and female was carried out by using student 's t - test .
statistical analysis was performed with statistical package for the social sciences software ( spss , version 10.5 ) package .
there were no significant difference between the morphological variables among the males and females , indicating that gender did not influence the regression model used to estimate chronological age for both female and male groups .
there were excellent intra and inter observer agreement between the paired sets of measurements carried out on the re - examined panoramic radiographs with correlation coefficient
pearson 's correlation coefficients between age and morphological variables showed that the variables ar ,
c correlated significantly with age , ar correlating the best among them ( correlation coefficient
r value -0.974 ) [ graph 1 ] . the ratios between length measurements correlated worst with age .
r was not significantly correlated with age ( p value 0.140 ) and was therefore excluded from further statistical analysis .
correlation between chronological age vs. morphological variables subjects age was modeled as a function of the morphological variables ( predictors ) , and to optimize the model , a stepwise linear regression analysis was performed to find these statistically significant predictors of chronological age .
( pulp / tooth area ratio ) and b ( pulp / root width at midpoint level between ecj level and mid - root level ) contributed significantly to the fit , yielding the following linear regression formula : age = 87.305480.455(ar)+48.108(b ) the regression equation with selected variables explained 96% of total variance ( r = 0.960 ) with the standard error of estimate of 3.0186 years and median of the residuals ( observed age minus predicted age ) of 0.1614 years .
stepwise regression analysis the scatter plot [ graph 2 ] shows that the values are equally distributed ; hence , the regression model fits the trend of the data reasonably well . the residual plot
[ graph 3 ] shows no obvious pattern and no outliers , hence supports our chosen regression model to estimate age .
scatter plot of predicted age vs. chronological age scatter plot of predicted age vs. residual there was no significant difference between chronological and estimated age for any of the age groups ( p value > 0.05 ) thus signifying that the derived formula is appropriate for all the selected age groups [ table 3 ] .
the apposition of secondary dentin can be indirectly measured by the reduction in pulp size in the radiographs . in 1925 , bodecker established that the apposition of secondary dentin correlated with age . in 1995 , kvaal et al .
, presented a method for age estimation , which was based on investigation of periapical radiographs , whereas paewinsky et al . , verified the applicability of this method on orthopantomograms . in 2004 , cameriere et al .
, for the first time conducted a preliminary study to evaluate the variations in pulp / tooth area ratio ( ar ) as an indicator of age and their method of age estimation seems promising .
the method originally examined the maxillary canine but subsequently included the second molar and mandibular canine .
while the authors obtained high levels of accuracy in age prediction ( mean error - 3 to 4.5 years ) , they advised that future research should investigate the effect of race and culture in model parameters .
indeed , others have also advocated the verification of age estimation methods on independent samples and some have concluded that best results are derived when population - specific formulas are used .
babshet et al . , found that cameriere 's formula , based on the italian population , is not as applicable to the indian population .
the present study was , therefore , undertaken to assess the chronological age of adults of karnataka origin .
maxillary canines were chosen as they are the single - rooted teeth with the largest pulp area and thus the easiest to analyze .
the smaller size of the other single - rooted teeth leads to less clear measurement of the pulp / root ratio . in multi - rooted teeth ,
in addition , in adult subjects , molars and premolars are often missing or damaged as a result of wear .
maxillary canines are normally the oldest teeth and undergo less wear as a result of diet than posterior teeth . since kvaal et al .
, did not find significant differences between teeth from the left and the right side of the jaw ; teeth from either the left or from the right side were processed depending on whichever were best suited for measurement . in the present study , there was excellent intra and inter observer agreement indicating that cameriere 's method is conducive to repeat measurements , both within and across examiners .
, had only evaluated intra - observer error and had advised that repetitive measurements must be carried out by other independent observers in order to verify inter - observer reproducibility . in the present study ,
pearson 's correlation coefficients between age and morphological variables showed that the variables ar ,
c correlated significantly with age , ar correlating the best among them ( correlation coefficient
subjects age was modeled as a function of the morphological variables ( predictors ) , and to optimize the model , a stepwise linear regression analysis was performed to find these statistically significant predictors of chronological age .
it was found that the variables ar and b contributed significantly to the fit , yielding the following linear regression formula : age = 87.305 480.455(ar)+48.108(b ) .
this was a new finding in our study contrary to the findings in previous studies by cameriere et al . , and saxena et al . , where the variables ar and c contributed significantly to the fit and yielded the formula for age estimation . in our study , it was found that the regression equation with selected variables explain 96% of total variance ( r = 0.960 ) with the standard error of estimate of 3.0186 years and median of the residuals ( observed age minus predicted age ) of 0.1614 years .
it is therefore comparable to other age estimation methods in adult . according to the study conducted by cameriere et al . ,
the regression equation , with the considered variables , explained 84.9% of total variance ( r = 0.849 ) with the standard error of estimate of 5.35 years and median of the residuals of 3.7 years . in the present study we got more accurate results .
study conducted by saxena et al . , showed 99.7% variance and 0.60 standard error of the estimate , when selected variables were used .
india has a population of mixed ethnicity and people belonging to various origins reside here but ethnicity was not considered in the study .
our study was conducted on indian population of karnataka origin ensuring ethnic uniformity of the study sample . in the present study
, there was no significant difference between chronological and estimated age for any of the age groups ( p >
0.05 ) signifying that the derived formula is appropriate for all the selected age groups .
the results of the study are promising ; however , it can not be generalized to other populations .
the study was limited to the maxillary canines because it is the long lasting tooth and is easiest to analyze due to largest pulp area among all the single - rooted teeth .
but , in conditions where these teeth are missing the method can not be employed . some questions concerning precision and accuracy of the measurements
so in future , image analysis programs which can recognize pulp outlines in radiographic images could be developed , which will be very useful in minimizing human manual measurements of morphological parameters , and will probably reduce both intra and inter observer variability .
thus , within the limitations of the present study , it can be concluded that there is significant correlation between age and morphological variables ar and b , and based on these variables chronological age can be determined with an accuracy of 96% in karnataka population .
the derived population specific regression equation can be potentially used for estimation of chronological age of individuals of karnataka origin .
Output:
| introduction : determination of age of a subject is one of the most important aspects of medico - legal cases and anthropological research .
radiographs can be used to indirectly measure the rate of secondary dentine deposition which is depicted by reduction in the pulp area.materials and methods : in this study , 200 patients of karnataka aged between 18 - 72 years were selected for the study .
panoramic radiographs were made and indirectly digitized .
radiographic images of maxillary canines ( ric ) were processed using a computer - aided drafting program ( imagej ) .
the variables pulp / root length ( p ) , pulp / tooth length ( r ) , pulp / root width at enamel - cementum junction ( ecj ) level ( a ) , pulp / root width at mid - root level ( c ) , pulp / root width at midpoint level between ecj level and mid - root level ( b ) and pulp / tooth area ratio ( ar ) were recorded .
all the morphological variables including gender were statistically analyzed to derive regression equation for estimation of age.results:it was observed that 2 variables ar and b contributed significantly to the fit and were included in the regression model , yielding the formula : age = 87.305480.455(ar)+48.108(b ) .
statistical analysis indicated that the regression equation with selected variables explained 96% of total variance with the median of the residuals of 0.1614 years and standard error of estimate of 3.0186 years.conclusion:there is significant correlation between age and morphological variables ar and b and the derived population specific regression equation can be potentially used for estimation of chronological age of individuals of karnataka origin . |
PubmedSumm118618 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: s f q has carried out the molecular , hapmap and in - silico analysis described in this manuscript and has compiled the manuscript .
a a has helped to carry out the in - silico analysis described in this manuscript .
the probands described in this manuscript have been diagnosed for lqt syndrome by m p j , c v , j s and h r at their respective hospitals .
k t has been critical in the review and compilation of the manuscript . as the corresponding author , the concept , design and compilation of this manuscript has been carried out by p n.
the study has been approved by the institutional ethics committee , dept . of genetics , osmania university ,
Output:
| heterogeneity in clinical manifestations is a well - known feature in long qt syndrome ( lqts ) .
the extent of this phenomenon became evident in families wherein both symptomatic and asymptomatic family members are reported .
the study hence warrants genetic testing and/or screening of family members of lqts probands for risk stratification and prediction.of the 46 families screened , 18 probands revealed novel variations / compound heterozygosity in the gene / s screened .
families 14 revealed probands carrying novel variations in kcnq1 gene along with compound heterozygosity of risk genotypes of the scn5a , kcne1 and nppa gene / s polymorphisms screened .
it was also observed that families- 5 , 6 and 7 were typical cases of anticipation in which both mother and child were diagnosed with congenital lqts ( clqts ) .
families- 16 and 17 represented alqts probands with variations in iks and ina encoding genes .
first degree relatives ( fdrs ) carrying the same haplotype as the proband were also identified which may help in predictive testing and management of lqts .
most of the probands exhibiting a family history were found to be genetic compounds which clearly points to the role of cardiac genes and their modifiers in a recessive fashion in lqts manifestation . |
PubmedSumm118619 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: semantic dementia ( sd ) is a clinical syndrome that is characterised by progressive , selective breakdown of verbal and non - verbal ( multimodal ) knowledge systems .
the disorder is associated with focal brain atrophy predominantly involving the anterior left temporal lobe1 and is distinct clinically , anatomically and pathologically from alzheimer disease .
music is a specialised dimension of non - verbal cognition;2
4 however , the effects of sd on music processing have not been studied . here
a 56-year - old right - handed female book keeper exhibited insidiously progressive deterioration of language , manifesting as reduced vocabulary and empty , circumlocutory but grammatical speech .
the patient subsequently developed impaired recognition of familiar faces and everyday objects , executive dysfunction and behavioural changes including sweet tooth and mild disinhibition .
she became increasingly interested in music , listening to cds of popular songs for many hours each day and singing or humming along to these songs and music on television .
brain mri and general neuropsychological assessments were undertaken 3 years and 5 years after clinical onset .
brain mri initially showed selective atrophy of the anterior left temporal lobe predominantly involving the temporal pole and the fusiform , inferior and middle temporal gyri
subsequently , there was extension of the atrophy to involve the right antero - inferior temporal lobe and orbitofrontal cortex .
at the first neuropsychological assessment , the patient displayed predominant impairments of naming and of single - word comprehension ( both < 5 percentile ) with surface dyslexia ( supplementary table 1 online ) . by the time of the second assessment , the patient had widespread deficits with profound impairment of both verbal and non - verbal semantic memory ( at floor on synonyms , famous faces recognition and easy british picture vocabulary scale rests ) .
the patient was asked to continue singing or humming familiar tunes after hearing a brief introduction .
forty tunes were chosen ( supplementary table 2 online ) : 10 popular songs of the 1960s and 1970s to which she listened regularly ( identified by her family ) , 10 common nursery rhymes and 20 other tunes well - known to british subjects ( e.g. auld lang syne , jerusalem ) .
the first four to eight musical bars of each tune were presented , whereas for the popular songs and nursery rhymes the first line was sung ( with lyrics ) by one of the authors ( jh ) . for the british tunes ,
another of the authors ( ro ) played the introduction on the piano as a single line melody without harmony or vocal accompaniment .
british tunes were also administered to three healthy non - musician female control subjects ( ages 6472 ) with no history of tone deafness , who were asked to demonstrate recognition of the tunes . to compare musical and verbal performance ,
the patient was assessed on verbal tasks analogous to the musical continuations ( supplementary table 2 ) .
she was presented with spoken first lines of the pop songs and nursery rhymes , and five sentences requiring high frequency terminal words ( e.g. she posted the letter without a [stamp] ) and six common idioms ( e.g. bread and [ butter] ) .
the patient sang an accurate ( unambiguous ) continuation of the melody for 25 of the 40 tunes ( figure 1 ; supplementary table 2 ) : 7 of the 10 pop songs , 6 of the 10 nursery rhymes and 12 of the 20 british tunes .
her performance on british tunes was comparable or somewhat inferior to recognition performance of the older control subjects ( mean control score 13 out of 20 , range 1216 ) .
do , producing accompanying lyrics for three pop songs ( average 5.3 words ) and five nursery rhymes ( average 1.6 words ) . in those cases where the patient did not continue the tune correctly , she produced an alternative continuation that was meaningful melodically ( ending on the tonic or the dominant of the key ) or rhythmically ( ending with a long or stressed final note ) .
she was able to provide a verbal continuation for only 5 of the 20 spoken song lyrics and nursery rhymes ( between 1 and 3 words in these cases ) and was unable to provide any high frequency sentence or idiom completions .
examples of musical continuations provided by the patient for pop songs , well - known british tunes and nursery rhymes . for each tune ,
melody ( the correct continuation ) is shown above and the patient s response has been transcribed below .
this case suggests that knowledge of music may be disproportionately preserved in sd compared with other modalities of knowledge .
debate continues regarding the nature of musical knowledge and the relative contributions of semantic , episodic and procedural factors.2
4 indeed , episodic and procedural ( motor activity ) memory are often spared in sd and might support some kinds of musical memory .
it is unlikely , however , that our patient s ability to continue familiar tunes depended entirely on episodic recall , since the tunes were presented in a non - standard form with both instrumental context ( sung or played on piano ) and harmonic context ( transposed in key ) altered .
this suggestion is consistent with other evidence that knowledge of familiar music does not depend on episodic memory.2
3 it is also unlikely that our patient s performance was driven solely by procedural memory : only around a quarter of the tunes were sung regularly by the patient , and half were presented on the piano , which she had never played .
rather than reactivating an episode from memory or a stored motor programme , the continuation of the tunes required , therefore , active translation of heard music into a new vocal output .
we argue that this translation process is mediated by brain knowledge stores ( semantic memory ) for music . besides retained knowledge of particular songs , the patient s ability to supply alternative musical continuations in accord with the melodic and rhythmic
the present case supports previous studies suggesting that knowledge of music has brain substrates that are partly separable from those mediating other forms of verbal and nonverbal knowledge.3
4 functional imaging evidence in normal individuals suggests that semantic memory for familiar tunes is mediated by a distributed network that includes the bilateral medial and orbital frontal cortex , the left angular gyrus and the left anterior middle temporal gyrus.3 we do not claim that musical semantic memory was entirely normal in our patient ; however , the present findings suggest that the anterior left temporal lobe may be less critical for musical than for other forms of semantic memory .
we propose that musical knowledge may be differently represented in the brain because musical objects ( such as melodies ) are essentially abstract , unlike visual objects , environmental sounds and other objects of sensory perception .
this differentiation could be functional as well as anatomical : it is likely that factors such as emotional content , arousal and context have an important influence on the encoding and retrieval of musical versus other kinds of memories .
moreover , knowledge for different kinds of musical information may have distinct substrates.4 relative sparing of musical knowledge may contribute to musicophilia in patients with frontotemporal lobar degenerations5 and may have implications for the use of music therapy and music - based cognitive rehabilitation .
Output:
| the brain basis for music knowledge and the effects of disease on music cognition are poorly understood .
here we present evidence for relatively preserved knowledge of music in a musically untrained patient with semantic dementia and characteristic asymmetric anterior temporal lobe atrophy .
our findings suggest that music is partly separable neuropsychologically and anatomically from other semantic domains , with implications for the clinical management of patients with brain disease . |
PubmedSumm118620 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: to determine how sdf-1/cxcr4 activates nuclear factor - kappa b ( nf-b ) and promotes oral squamous cell carcinoma ( oscc ) invasion .
nf-b activation was evaluated by western blot analysis and electrophoretic mobility shift ( emsa ) .
we show that the activation of nf-b by cxcr4 occurs through the carma3/bcl10/malt1 ( cbm ) complex in oscc .
we found that loss of components of the cbm complex in hnscc can inhibit sdf-1 induced phosphorylation and degradation of ib , while tnf induced ikk activation remains unchanged .
further , we identified a role for novel and atypical , but not classical , pkcs in activating ikk through cxcr4 .
importantly , inhibition of the cbm complex leads to a significant decrease in sdf-1 mediated invasion of oscc .
targeting molecular components of the nf-b signaling pathway may provide an important therapeutic opportunity in controlling the progression and metastasis of oscc mediated by sdf-1.
Output:
| aimto determine how sdf-1/cxcr4 activates nuclear factor - kappa b ( nf-b ) and promotes oral squamous cell carcinoma ( oscc ) invasion.methodologya lentivirus - based knockdown approach was utilized to deplete gene expression .
nf-b activation was evaluated by western blot analysis and electrophoretic mobility shift ( emsa).resultswe show that the activation of nf-b by cxcr4 occurs through the carma3/bcl10/malt1 ( cbm ) complex in oscc .
we found that loss of components of the cbm complex in hnscc can inhibit sdf-1 induced phosphorylation and degradation of ib , while tnf induced ikk activation remains unchanged .
further , we identified a role for novel and atypical , but not classical , pkcs in activating ikk through cxcr4 .
importantly , inhibition of the cbm complex leads to a significant decrease in sdf-1 mediated invasion of oscc.conclusionthe cbm complex plays a critical role in cxcr4-induced nf-b activation in oscc .
targeting molecular components of the nf-b signaling pathway may provide an important therapeutic opportunity in controlling the progression and metastasis of oscc mediated by sdf-1. |
PubmedSumm118621 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: progressive development of insulin resistance ( ir ) is a prediabetic state which is today a widespread metabolic abnormality of adults and adolescents in industrialised societies .
impaired insulin action is considered the first stage of type 2 diabetes mellitus ( t2 dm ) .
the consequences of ir manifest at many levels and in many metabolic processes , producing a cluster of homeostatic abnormalities including glucose intolerance , overt hyperglycemia , hyperinsulinemia , and atherogenic dyslipidemia , collectively referred to as metabolic syndrome ( mets ) .
liver steatosis , kidney disease , and osteoporosis are also frequent comorbidities of t2 dm and mets [ 24 ] .
ir correlates positively with obesity , and the rapidly growing incidence of t2 dm and mets is therefore often attributed to lifestyle factors such as excess caloric intake and insufficient physical exercise in urbanized human populations .
the main predisposing factor for ir is intra - abdominal accumulation of adipose tissue ( at ) , which leads to central obesity [ 5 , 6 ] .
the total load of visceral adipose tissue ( vat ) and the rate of free fatty acid ( ffa ) mobilization from vat to the portal venous system are well - established correlates of ir and high circulating levels of insulin [ 79 ] .
the elevated vat mass liberates excess amount ffas to the bloodstream , which contribute to muscle and liver ir by triggering reduced insulin signaling and increased hepatic gluconeogenesis .
high levels of ffa shift the substrate preference of mitochondrial oxidation from glucose to ffa , and this can diminish the insulin secretory response to glucose of islet -cells , leading to relative insulin insufficiency [ 10 , 11 ] . moreover ,
ffas induce an inflammatory response in macrophages , adipocytes , and muscle cells via toll - like receptor ( tlr ) activated pathways ( figure 1 ) .
modified lipoproteins such as oxidized and glycated low - density lipoproteins derived from excess vat can accumulate in certain tissues , including subendothelial spaces , muscle cells , liver or kidney mesangium and tubular epithelial cells , where they can give rise to atherogenesis , lipotoxic injury , and inflammation .
vat is also an active endocrine organ able to secrete a wide variety of inflammatory cytokines with key functions in the development of ir . in recent years , macrophages have been recognized as major sources of proinflammatory mediators , which are largely responsible for the manifestation of ir .
macrophages are plastic cells and their ability to produce cytokines is determined by their phenotype .
this situation creates a general subclinical inflammatory state that will ultimately lead to altered insulin responsiveness .
recent studies reveal that macrophage activation is regulated by lipid metabolites through the activation of nuclear receptor transcription factors , and that imbalances in macrophage nuclear receptor signaling can lead to ir . nuclear receptors ( nrs ) are a superfamily of ligand - activated transcription factors that control transcription of their target genes through direct or indirect mechanisms . directly ,
nrs bind to specific dna sequences in cis - regulatory elements within promoter regions , activating or repressing target gene expression by recruiting or releasing coactivators and corepressors .
indirectly , nrs can trans - repress the transcription of certain genes controlled by other transcription factors , such as nuclear factor kappa - b ( nf-b ) or activator protein-1 ( ap-1 ) [ 17 , 18 ] . prominent members of the nr superfamily are peroxisome proliferator activated receptors ( ppars ) , activated by ffas , eicosanoids , and prostaglandins , and liver x receptors ( lxrs ) , activated by cholesterol metabolites .
these lipid sensors appear to play a central role in the control of lipid metabolism .
nrs are moreover the targets of environmental obesogens such as phtalates , organotins , bisphenol a , and xenobiotics that interfere with nr signaling and which are thought to underlie the spread of obesity and its comorbidities .
in addition , evidence acquired over the last decade demonstrates that ppars and lxrs have important antiinflammatory effects and can control macrophage activation , suggesting potential in the medication of ir .
the role of nrs in linking metabolism and inflammation is especially relevant to the pathogenesis of obesity - induced ir .
synthetic pharmacological ligands for ppar ( thiazolidinediones ; tzds ) and ppar ( fibrates ) are used clinically due to their hypolipidemic and insulin - sensitizing properties .
additionally , pharmacological activation of lxrs results in increased hdl levels and net cholesterol loss , therefore , synthetic lxr ligands have a potential medical benefit to treat dyslipidaemias and atherosclerosis .
a growing body of literature suggests that these drugs , due to their antiinflammatory effects , can have a broader impact in metabolic diseases , especially in obesity comorbidities .
here we summarize the latest findings linking ir , inflammatory mediators , and macrophages and discuss the regulatory role of nr signaling in macrophage cytokine production associated with obesity and obesity comorbidities .
over the last few years , understanding of macrophages as an important element of ir development has advanced considerably with the identification of distinct functional macrophage subsets .
macrophages have a highly plastic phenotype that allows them to specialize and display polarized functional properties , such as inflammatory or antiinflammatory actions in response to cytokines and microbial products .
cytokines released by t - helper 1 ( th1 ) cells , such as interleukin-2 ( il-2 ) , gamma - interferon ( ifn ) , and tumor - necrosis factor alpha ( tnf ) , induce the classical macrophage phenotype , activating them to stimulate cellular immunity and inflammation .
th1 cells also secrete granulocyte - macrophage colony stimulating factor ( gm - csf ) , which promotes medullar monocyte / macrophage differentiation .
in contrast , t - helper 2 ( th2 ) cells secrete interleukin-4 ( il-4 ) and interleukin-13 ( il-13 ) , which induce an alternative phenotype by attenuating macrophage - mediated secretion of inflammatory mediators and instead inducing macrophage programs for ffa oxidation . adapting the th1/th2 nomenclature , mantovani and colleagues in 2002 started to refer to polarized macrophages as m1 and m2 cells .
m1 macrophages are activated proinflammatory cells , while m2 macrophages are characterized by an antiinflammatory phenotype . although there is a clear association of obesity and ir with macrophage infiltration of at and m1 macrophage activation ,
the dominant phenotype of adipose tissue macrophages ( atms ) is still an open debate .
the first evidence suggesting diversity of atm phenotype was obtained from chemokine receptor-2 ( ccr2 ) knockout ( ko ) mice ( ccr2ko ) .
ccr2 is a cell - surface receptor for monocyte chemoattractant protein-1 ( mcp-1 ) , a chemokine which specifically mediates monocyte chemotaxis . under normal physiological conditions ,
the atm content of ccr2ko at does not differ from wild - type at , and ccr2ko mice show no overt metabolic alteration . however , ccr2ko mice fed a high - fat diet accumulate fewer atms in at than similarly fed wild - type mice , and present an attenuated inflammatory profile and greater insulin sensitivity . thus metabolic challenge with supernormal fat intake triggers
macrophage recruitment to vat via a mcp-1/ccr2-dependent process , but ccr2 is not required for resident macrophage recruitment .
brake and co - workers subsequently identified cd11c - positive ( cd11c ) and cd11c - negative ( cd11c ) macrophage populations in mouse at .
the numbers of cd11c cells increase in response to a high - fat diet , and this is accompanied by increased at expression of transcripts for ccr2 , interleukin-6 ( il-6 ) , and intercellular adhesion molecule i ( icam - i ) , a leukocyte adhesion receptor needed for macrophage tissue infiltration .
interestingly , conditional bone marrow depletion of cd11c cells in obese mice results in a rapid normalization of insulin sensitivity .
moreover , further studies confirmed that atms recruited to at in diet - induced obesity express high levels of il-6 , inducible nitric oxide ( no ) synthase ( inos ) and ccr2 , all characteristics of the m1 phenotype [ 25 , 26 ] . in obese mice chronic inos blockade attenuates
high - fat diet induced ir and , similar to ccr2ko mice , reduces macrophage vat infiltration , as shown by lowered mrna expression of mcp-1 and the macrophage cell surface receptor cd68 .
in addition , resident atms show very low ( if any ) inflammatory activity and express many m2-associated genes such as arginase 1 , interleukin-10 ( il-10 ) and the secretory chitinase protein ym1 .
the identification of two monocyte populations in mouse blood [ 29 , 30 ] supported the hypothesis that m2 macrophages resident in at are descendents of circulating nonactivated monocytes , while m1 macrophages derive from a population of circulating inflammatory monocytes that are recruited to at where they continue their differentiation and orchestrate the inflammatory response .
this model is further supported by the observation that , blood mononuclear cells from obese patients are in a proinflammatory state .
an alternative hypothesis is that m1 macrophage polarization during obesity progression occurs via in situ reprogramming of atms from an m2 to an m1 phenotype . in vitro
, it is well established that the pattern of macrophage function depends on the agonist to which they are exposed .
for instance , in vivo , treatment of tumor - bearing animals with interleukin-12 ( il-12 ) shifts tumor - associated macrophages from a dominant m2 profile ( elevated expression of tgf , il-10 , and mcp1 ) to a proimmunogenic / inflammatory m1 profile ( elevated expression of il-6 and tnf ) . however , it remains uncertain whether this in situ phenotype switching can also occur in at ( figure 1 ) .
interestingly , ppar and ppar have been recently implicated in the transcriptional regulation of monocyte / macrophage phenotypic shift ( figure 1 ) .
using myeloid - specific ppar and ppar ko mice ( mac - pparko and mac - pparko ) , odegaard et al . showed that ppar and ppar are both necessary for optimal induction of the m2 macrophage phenotype by il-4 ( a classical th2 cytokine ) [ 34 , 35 ] .
however , these factors make distinct contributions to this process : ppar is specifically required for il-4-dependent activation of fatty acid oxidation , whereas ppar is required for the full expression of the il-4-dependent immune phenotype ( figure 1 ) .
furthermore , the at of fat - fed mac - pparko accumulates fewer macrophages and shows lower m2-related gene expression than the at of fat - fed wild - type mice .
however , fat - fed mac - pparko mice are more obese , indicating that the reduced number of m2 macrophages leads to major alterations in adipocyte metabolism .
these studies demonstrate that activation of ppar and ppar in atms ameliorates ir not only through the regulation of cytokine production but also by modulating atm phenotype .
vat is a major source of a wide variety of cytokines produced mainly by macrophages and of certain hormone - like factors produced by adipocytes .
the best known vat - produced cytokines include c - reactive protein ( crp ) , il-6 , interleukin-1 ( il-1 ) , interleukin-18 ( il-18 ) , and tumor necrosis factor ( tnf ) .
these inflammatory mediators exert their actions not only on at cells , but also on other cell types such as hepatocytes , liver kuppfer cells , kidney mesangial cells , osteoclasts , and muscle fibers .
indeed , in t2 dm patients , elevated vat expression of tnf is associated with the onset of ir , and high circulating levels of interleukin-1 receptor antagonist ( il-1ra ) and tnf correlate strongly with mets in human populations .
the mechanisms by which inflammatory cytokines produce defects in insulin signaling are not fully understood ; however , many studies suggest an origin in insulin postreceptor signaling . binding of insulin to its receptor
tyrosine phosphorylation of irs-1 and irs-2 mediates insulin signaling ; however , serine phosphorylation of irss can block downstream signaling .
there are thus two pathways by which cytokines appear to interfere in insulin signaling : by impairing irs tyrosine phosphorylation or by inducing irs serine phosphorylation .
for instance , tnf impairs tyrosine phosphorylation mediated by pi3-kinase , leading to insufficient glucose uptake by muscle cells [ 39 , 40 ] .
in addition , there is evidence implicating the serine kinases c - jun kinase ( jnk ) and inhibitor of nf-b kinase ( ikk ) in cytokine - dependent ir : obesity is associated with increased jnk activity in adipose and liver tissues and mice lacking ikk- are resistant to obesity - induced ir .
these kinases also affect ap-1 and nf-b transcription factors , promoting further inflammatory gene expression .
in addition , socs proteins , another class of inflammatory mediators , have been found to be involved in obesity - induced ir .
socs proteins block insulin signaling either by interfering with irs-1 and irs-2 phosphorylation or by targeting irss for proteosomal degradation [ 43 , 44 ] . studies on ppars and lxrs indicate that these nuclear receptors are important regulators of proinflammatory cytokine production by macrophages . in lps- or ifn-stimulated macrophages ,
activation of ppar represses the induction of inflammatory genes including inos , il-6 , cyclooxygenase-2 ( cox-2 ) , and matrix metalloproteinase 9 ( mmp9 ) [ 45 , 46 ] .
activation of lxrs represses almost the same genes as ppar [ 47 , 48 ] , while ppar shows a distinct pharmacological profile , inhibiting expression of tissue factor .
finally , ppar deficiency in macrophages is associated with low levels of mmp9 and mcp1 .
recently , increased cytokine production has been reported in vivo in the at , liver , and muscle of myeloid pparko mice , correlating with the development of ir in these animals .
most evidence indicates that the basic mechanism underlying the antiinflammatory actions of nrs is interference in ap-1/nfb signalling [ 17 , 18 ] .
for example , mechanisms involving blockade of the clearance of corepressor complexes from promoters have recently been proposed .
there thus appears to be no single mechanism of repression , and pathway selection seems to depend on the signal , the nr isoform involved , and even the gene promoter .
the ability of ppar and lxr receptors to control macrophage - mediated inflammation by these mechanisms appears to have an important impact on the control of ir .
indeed , the beneficial effect of weight loss on obesity - related ir might be associated with an improved inflammatory profile in the stromal vascular fraction of at , which contains the atms .
unlike other at related proteins , the adipocyte protein , adiponectin , contributes to the maintenance of insulin sensitivity and seems to be able to antagonize the proinflammatory effects of macrophages [ 54 , 55 ] .
adiponectin is the most abundant adipocyte - derived factor in the circulation and low levels of this protein are linked to high body mass index , ir , dyslipidemia , and increased risk of cardiovascular disease .
consistently , adiponectin immunostaining is reduced in the at of mice fed a fat- and carbohydrate - rich diet . in humans ,
a marked gender difference in at distribution evolves during puberty , resulting in elevated vat mass and lower adiponectin production in adult males and an associated higher susceptibility to insulin signaling defects [ 58 , 59 ] .
importantly , adiponectin also has a potent antiinflammatory action on macrophages , suppressing lipopolysaccharide ( lps)-stimulated cytokine production possibly via the antiinflammatory il-10 signaling pathway .
adiponectin promoter is regulated by ppar/rxr heterodimers , and administration of tzds has been reported to significantly increase plasma adiponectin concentrations in insulin - resistant humans and rodents without affecting their body weight .
activation of ppar induces production of adiponectin not only from adipocytes but also from skeletal muscle , which augments the antidiabetic actions of ppar [ 63 , 64 ] .
hepatocytes are actively involved in glucose and lipid metabolism ( including cholesterol and lipoprotein synthesis ) , plasma protein synthesis , and the production of inflammatory proteins such as crp .
obesity is associated with a high incidence of steatosis , a pathological accumulation of lipids within hepatocytes .
nonalcoholic fatty liver disease ( nafld ) is the most common form of chronic liver disease and is characterized by excess liver lipid accumulation and hepatic ir . at a later stage of disease progression , nafld can occur with hepatic inflammation , leading to nonalcoholic steatohepatitis ( nash ) and culminating in hepatic fibrosis or cirrhosis . in obesity , inflammatory cytokines ( il-1 , tnf , and il-6 ) and adiponectin released from at reach the liver through the portal vein and
tnf can trigger hepatocyte apoptosis and the activation of the fibrogenic response in stellate cells , while il-6 is implicated in the induction of the acute phase response by eliciting transcriptional activation of crp .
in addition , adiponectin exerts antifibrogenic effects : adiponectin ko mice exposed to ccl4 develop more severe fibrosis than wild - type animals
. however , the most important sources of inflammatory cytokines within the liver are kupffer cells , the resident macrophages in the liver .
kupffer cells mostly localize in the liver sinusoids but can also migrate into the space of disse .
like all macrophages , they show phenotypic plasticity , presenting different morphology and functions depending on their intralobular position .
kupffer cells located in the periportal zone are large cells with high phagocytosis capacity and high lysosomal protease activity , whereas kupffer cells in mid - zonal and perivenous areas are smaller and have lower protease activity [ 69 , 70 ] . during steatosis ,
the recruitment of new macrophages into the liver can alter cell distribution , thereby also changing kupffer cell morphology and function . indeed
, in the livers of nash patients , enlarged kupffer cells occur in aggregates around the perivenous regions , while in simple steatosis their distribution is more diffuse .
there is also evidence that th1 immune response dominates in nafld , promoting the classical m1 activation of kupffer cells [ 72 , 73 ] .
in addition , recent studies in rodents suggest a direct role for kupffer cell m1 activation in hepatic fatty acid metabolism and steatosis [ 74 , 75 ] .
interestingly , kupffer cells from rats , fed a high - fat diet or challenged with endotoxin , produce high levels of no and the tnf m1 cytokine [ 76 , 77 ] . moreover
, the depletion of kupffer cells prevents steatosis and the development of insulin resistance . in mice ,
kupffer cell depletion is also associated with a decrease in hepatic triglyceride levels and increased expression of key genes involved in fatty acid oxidation , such as ppar .
the ability of ppars and lxrs to reduce cytokine production in activated inflammatory monocyte - macrophage cells is well documented [ 4547 ] .
some studies show that pioglitazone , a clinically available ligand of ppar , prevents endotoxin - induced liver injury via a mechanism dependent on suppression of tnf and no production by kupffer cells [ 76 , 77 ] . in mouse liver , ppar activation
is associated with kupffer - cell mediated reactive oxygen species production and carcinogenesis . moreover , case reports indicate that therapeutic use of ppar ligands can lead to hepatic fibrosis .
contrary to these observations , ppar upregulation has been shown to ameliorate experimentally - induced liver steatosis in rats .
thus the common thread linking ppar activation , kupffer cells , and hepatic pathologies remains undefined .
kupffer cells can also be alternatively activated , and ppar has recently been shown to be required for this m2 activation of kupffer cells ( figure 2(a ) ) .
expression of m2 related genes in kupffer cells is reduced in ppar-deficient lean mice , and transplantation of ppar-null bone marrow into wild - type mice is enough to trigger hepatic dysfunction and systemic ir , probably due to reduced m2 activation of resident hepatic macrophages . in a similar way , myeloid - specific ppar mice fed a high - fat diet gain more weight , acquire a higher body weight / liver weight ratio , and have a more profound steatosis than control animals .
ppar is thus an interesting potential pharmacological target for the induction of m2 activation to control inflammation and improve steatosis in nafld .
clinical studies indicate that ir conditions such t2 dm and severe obesity are associated with increased fracture risk although not always with low bone mass [ 2 , 8587 ] . despite this association ,
it is likely that in humans diabetic bone is more fragile due to changes in bone architecture rather than as a consequence of the reduced bmd .
furthermore , leptin - deficient obese ( ob / ob ) mice , a model of obesity and ir , have a complex bone phenotype , displaying increased trabecular bone volume in the spine but short femora with reduced cortical thickness and reduced trabecular volume .
therefore , although ir is clearly associated with bone fragility , a direct effect of ir on bmd is highly controversial .
there is also a disputed association of obesity - associated bone fragility with several ir - derived defects , such as high insulin levels , low insulin - like growth factor-1 synthesis , low serum adiponectin , and elevated levels of inflammatory cytokines . under ir conditions , a compensatory hyperinsulinemia develops .
insulin appears to be anabolic for bone , and recent clinical studies demonstrate that elevated insulin levels can increase bmd .
adiponectin serum levels decrease with obesity , but osteoblasts and osteoclasts express receptors for adiponectin [ 91 , 92 ] , indicating a direct role of this factor in the regulation of bone homeostasis .
some reports linking obesity with increased bmd have demonstrated that adiponectin can promote bone resorption [ 93 , 94 ] .
in contrast , a recent study reports that adiponectin inhibits osteoclastogenesis in primary human cells in vitro and stimulates osteoblast growth .
these contradictory results suggest that the direct action of adiponectin on bone increases bmd , but that the final sum of its direct and indirect actions leads to bone mass reduction . moreover , bone architecture and mechanical properties unrelated to bmd can be impaired in patients with t2 dm , possibly due to the lowered levels of insulin - like growth factor-1 , a characteristic alteration in systemic ir
finally , inflammatory cytokines , including crp , il-1 , il-6 , and tnf , accelerate bone turnover and osteoclastogenesis , and may lead to reduced bmd in humans [ 9699 ] .
these studies illustrate the complexity of bone physiology and its paracrine / endocrine metabolic control , which makes it difficult to clarify the relationship between low bone mass , obesity , and ir . nevertheless , increased osteoclast activity and decreased osteoblast differentiation are the basis of bmd loss .
bone homeostasis is maintained by the equilibrium between the activities of bone - forming osteoblasts and bone - resorbing osteoclasts .
osteoclasts are derived from haematopoietic myeloid bone marrow progenitors whereas osteoblasts and adipocytes originate from bone marrow mesenchymal stem cells [ 101 , 102 ] .
given the importance of crosstalk between macrophages and adipocytes in obesity progression , the fact that macrophages and osteoclasts , and likewise adipocytes and osteoblasts , share common precursors suggests the existence of important interactions between bone and fat .
osteoclasts and osteoblasts also produce factors capable of influencing at biology , such as osteocalcin or osteopontin .
osteocalcin is secreted by osteoblasts and modulates the expression of various genes in adipocytes and insulin secreting -cells in pancreatic islets .
osteopontin , which is produced by various cell types such as macrophages , hepatocytes and osteoclasts , promotes inflammation and macrophage accumulation in at .
these findings suggest that bone has endocrine functions through which it might be involved in obesity progression
. however , there is little published research into the possible contribution of crosstalk between fat and bone to the regulation of energy balance .
paradoxically , administration of the insulin sensitizing synthetic ligands of ppar can induce bone loss and increase the risk of bone fractures [ 106 , 107 ] . in mice ,
consistently , macrophage - specific deletion of ppar leads to elevated bmd due to altered osteoclast activity .
it is also documented that ppar can control osteoblast differentiation from common bone marrow mesenchymal precursors of the osteoblast / adipocyte lineages .
mice with ppar haploinsufficiency therefore also have high bmd , coupled with reduced bone marrow adiposity .
lxr ko mice show a significantly increased bmd coupled to paradoxically elevated number of osteoclasts in cortical bone , suggesting that lxrs promote osteoclast resorption activity but is not necessary for osteoclast differentiation .
conversely , ligands of ppar , ppar , and ppar were recently shown to inhibit the formation of multinucleated osteoclasts from human blood monocytes in vitro ( figure 2(b ) ) .
the use of insulin sensitizing and hypolipidemic drugs , such as ppar and lxr ligands , might , by decreasing bmd , be related to the increased fracture risk observed in t2 dm patients .
however , it is still unknown to what extent bmd contributes to increased fracture risk and whether ir has a direct effect on bmd .
insulin resistance is the fundamental cause of a broad range of metabolic abnormalities including glucose intolerance , overt hyperglycemia , hyperinsulinemia , atherogenic dyslipidemia , cardiovascular diseases , kidney disease , liver steatosis , and osteoporosis .
obesity - associated chronic inflammation is a key contributor to decreased insulin signaling throughout the disease progression , although the specific mechanisms that link inflammation to ir remain not fully understood . the latest advances in the understanding of macrophage biology place macrophages as the drivers of this inflammatory response .
recruitment of m1 inflammatory macrophages and increased cytokine production in at and liver not only perpetuate inflammation in these organs but also influence other tissue functions .
for instance , obesity - associated inflammatory effects on bone physiology are well documented in many clinical studies . however , the results are controversial and difficult to interpret , and there is therefore a need for further studies to address this question and clarify whether ir has direct effects on bone homeostasis . the functions of ppar and lxr nuclear receptors in macrophages include the control of both metabolic and inflammatory pathways .
activation of these receptors thus acts as a link between these two processes closely related to the development of ir .
a large body of evidence clearly shows that the insulin - sensitizing properties of nrs are , at least in part , a result of inflammatory control in macrophages . a better understanding of the molecular mechanisms by which nrs control macrophage activation would therefore facilitate the development of pharmacological strategies to specifically target pathways regulating obesity before the onset of obesity - associated complications .
Output:
| visceral obesity is coupled to a general low - grade chronic inflammatory state characterized by macrophage activation and inflammatory cytokine production , leading to insulin resistance ( ir ) .
the balance between proinflammatory m1 and antiinflammatory m2 macrophage phenotypes within visceral adipose tissue appears to be crucially involved in the development of obesity - associated ir and consequent metabolic abnormalities .
the ligand - dependent transcription factors peroxisome proliferator activated receptors ( ppars ) have recently been implicated in the determination of the m1/m2 phenotype .
liver x receptors ( lxrs ) , which form another subgroup of the nuclear receptor superfamily , are also important regulators of proinflammatory cytokine production in macrophages . disregulation of macrophage - mediated inflammation by ppars and lxrs therefore underlies the development of ir .
this review summarizes the role of ppar and lxr signaling in macrophages and current knowledge about the impact of these actions in the manifestation of ir and obesity comorbidities such as liver steatosis and diabetic osteopenia . |
PubmedSumm118622 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: one - quarter of smokers develop chronic obstructive pulmonary disease , which is the fourth most common cause of death worldwide and is largely caused by smoking .
fukuchi et al . reported that the prevalence of chronic obstructive pulmonary disease in japanese patients increased steeply in individuals aged 60 years and older , from 5.8% in those aged 5059 years to 15.7 and 24.7% in those aged 6069 years and 70 years and older , respectively .
the number of patients with insidious chronic obstructive pulmonary disease is estimated to exceed five million , but more than 95% of cases are currently undiagnosed , and many of them are not treated .
early diagnosis of chronic obstructive pulmonary disease could encourage smoking cessation and improve quit rates in individuals most vulnerable to lung damage .
one approach used to increase the smoking cessation rate is the sharing of spirometric results with smokers . the concept of lung age was developed in 1985 as a way of making spirometric data easier to understand for patients and also as a psychological tool to show smokers the apparent premature ageing of their lungs . in the original formula developed by morris and temple , the regression equation constructed for predicting the reference value of forced expiratory volume in 1s ( fev1 ) from age and height was rearranged to solve for age. to date , several groups have reported revised equations for predicting lung age in populations worldwide . in japan
we have often used the regression equations reported by the japanese respiratory society ( jrs ) to calculate patient lung age .
however , we have found that the jrs equations show a discrepancy between lung age and lung damage , especially in japanese males . occasionally , healthy males had a large lung age deficit ( lung age minus chronological age ) , despite their status as never / non - smokers .
the aim of the present study was to establish novel regression equations using data from a large number of healthy never - smokers with normal spirometric measurements and normal body mass indices ( bmis ) .
the participants in the discovery cohort were selected from 104,563 individuals undergoing a 1-day standardised medical check - up at the center for preventive medicine of st luke 's international hospital between january 2004 and december 2012 .
a questionnaire was administered to subjects to obtain information about smoking status , past and present disease status and current medications .
subjects who indicated that they had never smoked before the health screening examination were identified as never - smokers and comprised 63,224 patients ( 20,184 males and 43,040 females ) . the never - smokers who reported no past or present diseases , such as cardiovascular disease , cancer , hypertension , dyslipidaemia ,
diabetes mellitus , gout and lung disease , were identified as healthy never - smokers ( n=21,832 ) .
healthy never - smokers who were taking medications at the time of the medical check - up were excluded . among healthy never - smokers with no current medications , we included those with normal spirometric measurements : % fev1 ( a proportion of fev1 divided by the forced vital capacity ( fvc))>70% and % fvc ( a proportion of fvc divided by the predicted fvc value)>80% and normal bmis ( 18.5<bmi<25.0 ) .
1-day check - up healthy never - smokers with normal spirometric measurements and normal bmis ( supplementary figure 1 ) and enroled them as group 1 ( n=15,238 , including 5,499 males and 9,739 females ; table 1 ) .
the participants in the validation cohort were selected from an initial population of 5,595 individuals receiving a comprehensive overnight check - up at the center for preventive medicine of st luke 's international hospital between january 2004 and december 2012 .
similar to the process for group 1 , we selected japanese subjects who reported no past or present diseases as candidates for enrolment in group 2 , which constituted the study group of comprehensive overnight check - up healthy subjects. a total of 2,079 participants ( n=1,294 males and 785 females ) met the criteria and were included in the study ( table 1 ) .
baseline data included age at check - up , anthropometric variables ( height , weight , bmi , waist circumference and blood pressure ) , smoking history ( never / non - smoker , ex - smoker or current smoker ) , medical history , current medications and co - morbidities , including chronic bronchitis or emphysema , asthma or other lung diseases .
all participants underwent standard measurements of lung function ( fev1 , % fev1 , fvc and % fvc ) with a spirometer ( discom-21 ; chest mi inc . ,
the lung age of participants was calculated by working back from the regression equations predicting reference values of fev1 reported by the jrs and our novel regression equation .
the following jrs equations were used :
fev1(l)=0.022height(cm)0.022age(years)0.005infemales
fev1(l)=0.036height(cm)0.028age(years)1.178inmaleswe calculated the spirometric - derived lung age ( sdl age ) using the following equations : sdlage=(0.022height(cm)0.005fev1(l))/0.022infemales
sdlage=(0.036height(cm)1.178fev1(l))/0.028inmalesthe lung age deficit was defined as the difference between sdl age and chronological age .
we used the original method of morris and temple in which the assumption is that the lung age can be expressed as a linear function of fev1 and height ( cm ) .
data were analysed separately for female and male participants using multiple linear regressions and the enter method .
the difference in lung age deficits between more than three categories was analysed using the kruskal
data were analysed using spss statistical software version 22.0 ( ibm japan , tokyo , japan ) .
we excluded the records of individuals who had declined to participate in the clinical study .
this study was approved by the institutional research board of st luke 's international hospital .
the participants in the discovery cohort were selected from 104,563 individuals undergoing a 1-day standardised medical check - up at the center for preventive medicine of st luke 's international hospital between january 2004 and december 2012 .
a questionnaire was administered to subjects to obtain information about smoking status , past and present disease status and current medications .
subjects who indicated that they had never smoked before the health screening examination were identified as never - smokers and comprised 63,224 patients ( 20,184 males and 43,040 females ) .
the never - smokers who reported no past or present diseases , such as cardiovascular disease , cancer , hypertension , dyslipidaemia , diabetes mellitus , gout and lung disease , were identified as healthy never - smokers ( n=21,832 ) .
healthy never - smokers who were taking medications at the time of the medical check - up were excluded . among healthy never - smokers with no current medications , we included those with normal spirometric measurements : % fev1 ( a proportion of fev1 divided by the forced vital capacity ( fvc))>70% and % fvc ( a proportion of fvc divided by the predicted fvc value)>80% and normal bmis ( 18.5<bmi<25.0 ) .
1-day check - up healthy never - smokers with normal spirometric measurements and normal bmis ( supplementary figure 1 ) and enroled them as group 1 ( n=15,238 , including 5,499 males and 9,739 females ; table 1 ) .
the participants in the validation cohort were selected from an initial population of 5,595 individuals receiving a comprehensive overnight check - up at the center for preventive medicine of st luke 's international hospital between january 2004 and december 2012 .
similar to the process for group 1 , we selected japanese subjects who reported no past or present diseases as candidates for enrolment in group 2 , which constituted the study group of comprehensive overnight check - up healthy subjects. a total of 2,079 participants ( n=1,294 males and 785 females ) met the criteria and were included in the study ( table 1 ) .
baseline data included age at check - up , anthropometric variables ( height , weight , bmi , waist circumference and blood pressure ) , smoking history ( never / non - smoker , ex - smoker or current smoker ) , medical history , current medications and co - morbidities , including chronic bronchitis or emphysema , asthma or other lung diseases . all participants underwent standard measurements of lung function ( fev1 , % fev1 , fvc and % fvc ) with a spirometer ( discom-21 ; chest mi inc . , tokyo , japan ) .
the lung age of participants was calculated by working back from the regression equations predicting reference values of fev1 reported by the jrs and our novel regression equation .
the following jrs equations were used :
fev1(l)=0.022height(cm)0.022age(years)0.005infemales
fev1(l)=0.036height(cm)0.028age(years)1.178inmaleswe calculated the spirometric - derived lung age ( sdl age ) using the following equations : sdlage=(0.022height(cm)0.005fev1(l))/0.022infemales
sdlage=(0.036height(cm)1.178fev1(l))/0.028inmalesthe lung age deficit was defined as the difference between sdl age and chronological age .
we used the original method of morris and temple in which the assumption is that the lung age can be expressed as a linear function of fev1 and height ( cm ) .
data were analysed separately for female and male participants using multiple linear regressions and the enter method .
the difference in lung age deficits between more than three categories was analysed using the kruskal
data were analysed using spss statistical software version 22.0 ( ibm japan , tokyo , japan ) .
we excluded the records of individuals who had declined to participate in the clinical study .
this study was approved by the institutional research board of st luke 's international hospital .
the demographic data of group 1 and group 2 participants are shown in table 1 .
the mean age of group 1 was about 20 years less than that of group 2 . in group 1 ,
75 and 78% of subjects were between ages 30 and 50 among males and females , respectively , whereas in group 2 this was 14 and 15% .
all subjects in group 1 were never - smokers , whereas group 2 included never - smokers , ex - smokers and current smokers .
height and weight were similar in the two groups , but the subjects in group 2 had slightly higher bmis and waist circumference compared with group 1 .
the scatter plots of the relationship between chronological age and fev1 in females and males are shown in figure 1 .
fvc also declined continuously and almost linearly over chronological ages ; however , there was a wider spread of data ( supplementary figure 2 ) .
table 2 shows the results of the representative multiple linear regression analysis of models 13 .
model 1 included two predictive variables ( height and weight ) , similar to the jrs report .
model 2 was created by adding one additional variable ( % fvc ) and model 3 was created with spirometric variables only ( fvc ( l ) and % fvc ) excluding a height variable .
supplementary table 1 shows a comparison of the other model equations ; models 4 , 5 , 6 and 7 were created by adding one additional variable ( weight ( w ) bmi , waist circumference , fvc , % fvc and % fev1 and fvc ( l ) , respectively ) .
the fitness of the model was not improved by adding the other anthropometric variables . however , the addition of fvc data significantly improved the performance of the model ( the adjusted r values > 0.8 ) and multicollinearity was suspected between some variables ( supplementary table 2 ) .
we developed the sdl age estimation equations according to the models described above and shown in table 2 .
the representative scatter plots between chronological age and sdl age are shown in figure 2 .
we compared models 2 and 3 with the original jrs model . on the basis of the r values , the slope ( nearly equal to 1 ) and its simplicity
( only two predictive variables ) , model 3 was considered the best model in both females ( r=0.66 ) and males ( r=0.55 ) .
the box and whisker plots of lung age deficit ( lung age minus chronological age ) sorted by age group are shown in figure 3 .
compared with model 3 , the lung age deficit values from the jrs equations were more widely distributed , indicating a larger discrepancy between sdl age and chronological age when using the jrs method .
in addition , the lung age deficit values in males tended to be positive in the jrs method , suggesting an overestimation of sdl age in all age groups , whereas the lung age deficit values using model 3 were distributed around zero in all age groups , suggesting appropriate prediction of sdl age in all age groups .
the scatter plots of the relationships between chronological age and sdl age in never - smokers with normal spirometric measurements and normal bmis in group 2 are shown in figure 4 .
similar to group 1 , model 3 was considered the best model in both females and males because of the values of r. however , the slopes of model 2 and model 3 were from 0.73 to 0.80 ( there were some discrepancies to 1 ) .
the box and whisker plots of the lung age deficit according to smoking status in group 2 are shown in supplementary figure 3 .
similar to group 1 , the lung age deficit values distributed more widely in the jrs method compared with model 3 .
this study produced the following novel sdl age equations using data from a large number of healthy never - smokers with normal spirometric measurements and normal bmis : sdl age ( females)=0.84%fvc+50.240fev1 ( l ) , and sdl age ( males)=1.00%fvc+50.733.3fev1 ( l ) .
the jrs has developed standardised equations for determining the lung age in the japanese population based on the original method of morris and temple .
second , the jrs equations produced discrepant results between lung age and lung damage , especially in japanese males . occasionally , healthy males who were healthy never - smokers showed a large lung age deficit .
in addition , it is not self - evident whether lung age can be reliably predicted from the single spirometric parameter of fev1 . to our knowledge ,
the american thoracic society guidelines for spirometry recommend that predictive equations be derived from a
the lung age equations currently used in japan were developed by the jrs in 2001 ; thus , adequately updated equations using data from the japanese population will be indispensable for appropriate evaluation of lung age .
the fitness of the model was not improved by adding the other anthropometric variables , but the addition of fvc information improved the adjusted r values significantly .
models 2 and 3 had a comparable ability for predicting sdl age ; however , we selected model 3 as the best model because , first , the ideal equations should be as simple as possible and , second , because model 3 in both females and males revealed not only higher values of r but also nearer to 1 as the slopes in the validation cohort ( group 2 ) .
one strength of the current study is that our model was developed using a large sample size ( n=15,238 ) of healthy never - smokers with normal spirometric measurements and normal bmis .
in addition , these sdl age equations used two different spirometric parameters , fev1 and % fvc . it is well known that these two values reflect different aspects of lung damage .
the results of this study should be interpreted in the context of the acknowledged limitations .
first , this study was conducted in only one hospital ( st luke 's international hospital ) , and the socioeconomic status of our participants does not seem to be representative of the general population of japanese patients .
our participants might consist of higher - income upper - class individuals , with white collar occupations .
however , data on occupational and other environmental exposure were not available in this study .
second , yomaguchi et al . suggested that the simple backward calculation of age from the regression equation for the reference value of fev1 may not be appropriate from statistical points of view .
we used contemporary data to produce novel sdl age equations for japanese adults aged 1880 years .
international guidelines suggest that lung function equations should be derived from the same population to which they will be applied and should be updated regularly .
appropriate sdl age equations can be used to give a more powerful message to motivate people to quit smoking .
further research is needed to validate these equations using other populations with large sample sizes .
we developed novel sdl age equations using fev1 and % fvc from 15,238 japanese healthy never - smokers with normal spirometric measurements and bmi .
this study produced the following novel sdl age equations using data from a large number of healthy never - smokers with normal spirometric measurements and normal bmis : sdl age ( females)=0.84%fvc+50.240fev1 ( l ) , and sdl age ( males)=1.00%fvc+50.733.3fev1 ( l ) .
the jrs has developed standardised equations for determining the lung age in the japanese population based on the original method of morris and temple .
second , the jrs equations produced discrepant results between lung age and lung damage , especially in japanese males . occasionally , healthy males who were healthy never - smokers showed a large lung age deficit .
in addition , it is not self - evident whether lung age can be reliably predicted from the single spirometric parameter of fev1 . to our knowledge ,
the american thoracic society guidelines for spirometry recommend that predictive equations be derived from a
the lung age equations currently used in japan were developed by the jrs in 2001 ; thus , adequately updated equations using data from the japanese population will be indispensable for appropriate evaluation of lung age .
the fitness of the model was not improved by adding the other anthropometric variables , but the addition of fvc information improved the adjusted r values significantly .
models 2 and 3 had a comparable ability for predicting sdl age ; however , we selected model 3 as the best model because , first , the ideal equations should be as simple as possible and , second , because model 3 in both females and males revealed not only higher values of r but also nearer to 1 as the slopes in the validation cohort ( group 2 ) .
one strength of the current study is that our model was developed using a large sample size ( n=15,238 ) of healthy never - smokers with normal spirometric measurements and normal bmis .
in addition , these sdl age equations used two different spirometric parameters , fev1 and % fvc . it is well known that these two values reflect different aspects of lung damage .
the results of this study should be interpreted in the context of the acknowledged limitations .
first , this study was conducted in only one hospital ( st luke 's international hospital ) , and the socioeconomic status of our participants does not seem to be representative of the general population of japanese patients .
our participants might consist of higher - income upper - class individuals , with white collar occupations .
however , data on occupational and other environmental exposure were not available in this study .
second , yomaguchi et al . suggested that the simple backward calculation of age from the regression equation for the reference value of fev1 may not be appropriate from statistical points of view .
we used contemporary data to produce novel sdl age equations for japanese adults aged 1880 years .
international guidelines suggest that lung function equations should be derived from the same population to which they will be applied and should be updated regularly .
appropriate sdl age equations can be used to give a more powerful message to motivate people to quit smoking .
further research is needed to validate these equations using other populations with large sample sizes .
we developed novel sdl age equations using fev1 and % fvc from 15,238 japanese healthy never - smokers with normal spirometric measurements and bmi .
Output:
| background : the lung age equations developed by the japanese respiratory society encounter several problems when being applied in a clinical setting.aims:to establish novel spirometry - derived lung age ( sdl age ) equations using data from a large number of japanese healthy never - smokers with normal spirometric measurements and normal body mass indices ( bmis).methods : the participants had undergone medical check - ups at the center for preventive medicine of st luke 's international hospital between 2004 and 2012 .
a total of 15,238 japanese participants ( 5,499 males and 9,739 females ) were chosen for the discovery cohort .
the other independent 2,079 individuals were selected for the validation cohort .
the original method of morris and temple was applied to the discovery cohort.results:as a result of the linear regression analysis for forced expiratory volume in 1 s ( fev1 ) , spirometric variables using forced vital capacity ( fvc ) improved the adjusted r2 values to greater than 0.8 . on the basis of the scatter plots between chronological age and sdl age , the best model included the equations using fev1 and % fvc in females and males ( r2=0.66 and 0.55 , respectively ) , which was confirmed by the validation cohort .
the following equations were developed : sdl age ( females)=0.84%fvc+50.240fev1 ( l ) and sdl age ( males)=1.00%fvc+50.733.3fev1 ( l).conclusions : this study produced novel sdl age equations for japanese adults using data from a large number of healthy never - smokers with both normal spirometric measurements and bmis . |
PubmedSumm118623 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: diarrhea still remains as one of the leading killer diseases of children under five in developing countries and accounts for 9% of 6.3 million global deaths in 2013 .
an earlier report from icddr , b has shown factors that were associated with an increased risk of death in bacteremic patients who were infected with a gram - negative pathogen ; however , among the gram - negative bacteremia , klebsiella is one of the most virulent pathogens and is often associated with high morbidity and mortality in children .
it has also been found to be the most common cause of pneumonia in severely malnourished children .
klebsiella bacteremia is perceived to be more common in diarrheal children compared to those without diarrhea and often have fatal outcomes . in resource - poor settings , where laboratory facilities are limited and blood culture is seldom done , clinical features may help in predicting klebsiella bacteremia in such children .
however , to our knowledge , there is no published data on the role of klebsiella bacteremia and its clinical features in diarrheal children .
the objective of our study was to evaluate the factors associated with klebsiella bacteremia in under - five diarrheal children and their outcome .
the study population was treated in the dhaka hospital of international centre for diarrhoeal disease research , bangladesh ( icddr , b ) and the description of the study site has been provided elsewhere .
all the diarrheal children under five who had their blood culture done between january 1 , 2010 , and december 31 , 2012 , were enrolled in the study .
a case - control design was deployed in the study where the children having klebsiella bacteremia constituted the cases and those without any bacteremia constituted the controls .
thus , we did not include the children with positive blood cultures for organisms other than klebsiella species as potential controls .
we had taken threefold controls using randomization process in the statistical package for social science ( spss ) to increase the power of our analysis .
management of the patients has been done following standardized protocol followed in the dhaka hospital of icddr , b and the management of hospitalized patient has also been described elsewhere .
data of all diarrheal children was retrieved from electronic medical record system ( named as sheba ) of dhaka hospital . after admission ,
case report forms ( crf ) were developed for this study , pretested , and finalised for data acquisition .
characteristics analyzed included demographics ( age , gender ) , nutritional status including severe wasting ( z score for weight for length / height < 3 of who growth standard ) and severe underweight ( z score for weight for age < 3 of who growth standard ) , abnormal mentation ( drowsiness , convulsion , or restlessness ) , fast breathing ( < 2 months : 60/min ; 2<12 months : 50/min ; 1259 months : 40/min ) , spo2 ( transcutaneously measured blood oxygen concentration ) , dehydration status , hypotension ( defined as systolic blood pressure 70 mm of hg or diastolic blood pressure 40 mm of hg or mean arterial pressure 50 mm of hg ) , hospital - acquired infection ( new episode of infection at least after 48 hours of hospitalization ) , laboratory investigation ( creatinine in micro - mol / l , stool culture for vibrio cholerae , shigella species , salmonella typhi , and other vibrios ) , and outcome ( deaths ) .
all data were entered into a personal computer and edited before analysis using spss for windows ( version 17.0 ; spss inc . , chicago , il , usa ) and epi info ( version 6.0 ; usd , stone mountain , ga , usa ) .
differences in proportions were compared by the chi - square test . in normally distributed data , differences in means
were compared by student 's t - test , and the mann - whitney test was used for comparing data that were not normally distributed .
strength of association was determined by calculating odds ratio ( or ) and their 95% confidence intervals ( cis ) . to identify clinical predictors associated with klebsiella bacteremia in diarrheal children
, variables were initially analyzed in a univariate model , and then , after adjusting for potential confounders , a multiple logistic regression model was used to identify the independent predictors of klebsiella bacteremia .
during the 3-year study period , a total of 3313 children fulfilled the study criteria and we only identified 30 ( 0.9% ) cases of klebsiella bacteremia . among the remaining 3283 children , 676 had bacterial isolates other than klebsiella species .
thus , we had randomly selected 90 controls among a total of 2607 children who had no growths in their blood culture and were available for the selection of the controls .
diarrheal children with klebsiella bacteremia more often presented at their infancy , received antibiotics prior to admission , and had severe dehydration , fever , abnormal mentation , severe wasting , and positive stool growth on admission and they frequently developed hospital - acquired infection and more often had fatal outcome during hospitalization compared to those without bacteremia ( table 1 ) .
in logistic regression analysis , after adjusting for potential confounders such as young age , severe dehydration , severe wasting , abnormal mentation , hypotension , and fast breathing , the cases were independently associated with hospital - acquired infection and positive stool growth ( table 2 ) .
importantly , klebsiella species causing bacteremia was found to have higher resistant ( 68% ) to ceftriaxone .
gram - negative bacteremia is a major cause of morbidity and mortality if undiagnosed on time [ 7 , 8 ] .
the observation of higher case fatality rate in children with klebsiella bacteremia compared to those without any bacteremia was expected .
we are not aware of any report on mortality due to klebsiella bacteremia in diarrheal children .
however , a number of previous studies in nondiarrheal children revealed that children with gram - negative bacteremia more often had fatal outcomes compared to those without bacteremia [ 7 , 8 ] . in this study
, we observed that the prevalence of klebsiella bacteremia is very low in children with diarrhea .
however , in a number of hospital based studies , a higher prevalence was demonstrated that ranged from 13% to 26% . in a study from ghana ,
also in the same age group reports from nigeria , ghana , and the united states , klebsiella accounts for 3 to 7% of all nosocomial bacterial infections .
the potential reasons for variations in prevalence of klebsiella bacteremia might be due to heterogeneity in geographical location , patient population , study design , or differences in prior antibiotic therapy .
moreover , all of our study children had diarrhea which was not present in those above - mentioned studies and that might be one of the reasons of variation in prevalence of klebsiella bacteremia in our study children . to our knowledge this is the first study that reported the data on klebsiella bacteremia in under - five diarrheal children from bangladesh .
one of the plausible reasons for the development of bacteremia in diarrheal children might be due to bacterial translocation through transcellular and paracellular pathways .
it mostly occurs in immune compromised children and impairment of normal ecological balance of gut , mucosal barrier permeability , and stress . in this study
, we found an independent association of hospital - acquired infection and positive stool growth with klebsiella bacteremia . on the other hand , young age , severe dehydration , severe wasting , and abnormal mentation
were associated with klebsiella bacteremia in a univariate analysis , although , in logistic regression analysis , their association with klebsiella bacteremia became insignificant .
while hypotension and fast breathing are the components of sepsis in adults following qsofa criteria and both in adults and children following surviving sepsis guidelines , these two variables did not have significant association with klebsiella bacteremia in our study children either by a univariate analysis or a logistic regression .
the us national healthcare safety network indicates that infection due to gram - negative bacteria is responsible for more than 30% of hospital - acquired infections .
klebsiella was found to be very common organism responsible for such type of infection in children . to our knowledge
, the observation of an independent association of klebsiella bacteremia with bacterial isolates from diarrheal stool in our study has been described for the first time in medical literature .
we do not have any ready explanation for this observation but altered gut function , mucosal damage , enteropathy , or absence of antibacterial peptide or loss of bacterial flora in diarrhea may have influences on translocation of klebsiella from the gut [ 11 , 15 ] .
we have also evaluated sensitivity for extended spectrum beta - lactam ( esbl ) antibiotics among klebsiella species and in our reference laboratory , the surrogate marker of esbl is ceftriaxone ; klebsiella species was found to have higher resistance ( 68% ) to ceftriaxone .
gram - negative bacteremia is relatively common in young age and occurs much less frequently after the first year of life .
infants had the highest incidence of gram - negative bacteremia among all children observed in a previous study , which is consistent with our study and klebsiella was one of the commonest organisms isolated .
the increased incidence of klebsiella bacteremia in young age might be due to less cellular and humoral immunity .
wasting is an important indicator of acute malnutrition which impairs the immune response and predispose to invasive infection .
comorbidity of diarrhea with malnutrition makes the child more vulnerable to invasive infection [ 11 , 18 ] .
a number of previous studies [ 1921 ] have been shown to have significant association of severe acute malnutrition with klebsiella bacteremia .
abnormal mentation as observed in this study was an associated factor with klebsiella bacteremia which may also be common in any bacteremia and might be due to compromised perfusion or systemic response to klebsiella bacteremia which is consistent with other studies with any bacteremia .
the main limitation is the retrospective nature of the study which involves a small number of samples that limited the power of the study and subsequently limited the generalisability of the study results .
another limitation is the lack of specification of klebsiella species into k. pneumoniae and k. oxytoca . in conclusion ,
diarrheal children under five with klebsiella bacteremia had greater case fatality rate compared to those without bacteremia .
the study highlights the importance of obtaining blood cultures in hospitalized children under five years old with diarrheal illness in the presence of either infancy , abnormal mentation , severe wasting , severe dehydration , hospital - acquired infection , or positive stool culture , although hospital - acquired infection and positive stool culture were identified as the independent risk factors for klebsiella bacteremia in our study population .
awareness and identification of these simple clinical characteristics may help in early case detection and management of klebsiella bacteremia and therefore help in reducing deaths in such children from developing countries .
however , further research in diarrheal children with klebsiella bacteremia with larger sample is warranted to substantiate our observation .
Output:
| although klebsiella bacteremia in children is perceived to be associated with fatal consequences , data are scarce on those children presenting with diarrhea .
we evaluated the factors associated with klebsiella bacteremia in such children . in this retrospective chart analysis ,
data of all diarrheal children was retrieved from electronic medical record system ( named as sheba ) of dhaka hospital of international centre for diarrhoeal disease research , bangladesh ( icddr , b ) , from january 1 , 2010 , to december 31 , 2012 , who had their blood culture done .
this was a study having a case - control design where comparison of clinical and laboratory characteristics was done among children with klebsiella bacteremia ( cases = 30 ) and those without any bacteraemia ( controls = 90 ) .
controls were selected randomly .
the cases more often had fatal outcome ( p < 0.001 ) . in logistic regression analysis , after adjusting for potential confounders such as young age , severe dehydration , severe wasting , abnormal mentation , hypotension , and fast breathing , the cases were independently associated with hospital - acquired infection and positive stool growth ( for all , p < 0.05 ) .
the study highlights the importance of obtaining blood cultures in hospitalized children under five years old with diarrheal illness in the presence of either hospital - acquired infection or positive stool culture to have better outcome . |
PubmedSumm118624 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: during the 2001 anthrax outbreak investigation , 135 b. anthracis isolates were subtyped . the identity of all strains was confirmed with standard microbiologic procedures and the laboratory response network ( lrn ) testing algorithm ( 9,10 ) .
isolates were obtained from patients with laboratory - confirmed anthrax ( n=10 ) , powders ( n=4 ) , and environmental specimens ( n=121 ) . for comparison purposes , five
b. anthracis isolates originating from new england in the 1960s and 1970s , the ames strain , and the pasteur strain were included .
dna extractions of 28 clinical specimens from six patients with confirmed inhalational anthrax were used for molecular subtyping .
these specimens included blood , pleural fluid , blood cultures , serum , cerebrospinal fluid ( csf ) , lung tissue , and lymph node tissue .
isolates were streaked onto trypticase soy agar containing 5% sheep blood ( becton dickinson microbiology systems , cockeysville , md ) and incubated overnight at 37c .
a single colony was transferred and dispersed into 0.22-m centrifugal filter units ( millipore , bedford , ma ) containing 200 l 10 mm tris - hcl ( ph 8.0 ) .
the filter units were then centrifuged in a microfuge at 6,000 x g for 2 min and the filter discarded .
dna from clinical specimens was extracted with a qiagen dna mini kit per manufacturer s instructions ( qiagen inc . ,
briefly , the eight loci were amplified in four reactions : reaction 1 ( vrrb1 , cg3 , and vrra ) , reaction 2 ( vrrb2 , pxo1-aat , and pxo2-at ) , reaction 3 ( vrrc1 ) , and reaction 4 ( vrrc2 ) . in some instances cg3
was removed from reaction 1 and amplified as a 5th reaction because of weak amplification .
products were separated by polyacrylamide gel electrophoresis under denaturing conditions on an abi 377 automated dna sequencer ( applied biosystems , foster city , ca ) , and allele sizes were determined using abi genescan software ( applied biosystems ) .
the amplification and sequencing of paga were performed on 42 b. anthracis isolates and 22 clinical specimens as described by price et al .
initially , synthetic oligonucleotide polymerase chain reaction ( pcr ) primers pa-1f and pa-1r and pa-2f and pa-2r ( table 1 ) were used to amplify two overlapping fragments ( 1,119 bp and 1,449 bp , respectively ) together totaling 2,531 bp and containing the paga open reading frame ( orf ) ( 8) .
because of inconsistent amplification with pa-2f and pa-2r and to generate a single template for sequencing , pcr amplification was performed using primers 1566f and 4205r . in some instances , possibly from the method of dna purification , 1566f and 4205r did not amplify sufficiently and thus nested pcr was performed using 1575f and 4191r .
the primers used in this study were a combination of both published primers ( 8) and primers designed from the published dna sequence of the virulence plasmid pxo1 ( genbank accession no .
the paga sequencing template was amplified by pcr using the expand high fidelity pcr system ( roche , mannheim , germany ) .
fifty - microliter pcr mixtures contained 10 mm tris - hcl ( ph 8.3 ) , 50 mm kcl , 4.0 mm mgcl2 , 0.4 mm of each forward and reverse primer , 100 m of each deoxynucleotide , 2.0 u of taq dna polymerase ( roche ) , and 2 l of bacterial lysate .
reactions were heated at 94c for 5 min and then cycled 35 times at 94c for 30 s , 51c for 30 s and 72c for 1.5 min , with a final extension of 72c for 5 min .
pcr amplicons were purified using qiaquick pcr purification kit ( qiagen , inc . ) and the resulting purified amplicons were used in the subsequent sequencing reactions .
sequencing was performed on an applied biosystems 3100 genetic analyzer ( applied biosystems ) using bigdye terminator cycle sequencing ready reaction mix according to manufacturers instructions ( applied biosystems ) .
all sequence data were analyzed with the lasergene 99 ( dnastar , madison , wi ) software , which comprises several different programs : dna sequences were assembled using the seqman program , and megalign was used to do sequence comparisons .
by mlva , all 135 outbreak - related b. anthracis isolates had the following loci sizes : vrra = 313 , vrrb1 = 229 , vrrb2 = 153 , vrrc1 = 583 , vrrc2 = 532 , cg3 = 158 , pxo1 = 123 , and pxo2 = 141 , resulting in genotype 62 , as described by keim et al . (
6 ) . in addition , the entire 2,294-bp paga gene was sequenced from a subset of 42 isolates : including ten patient isolates , all four powder isolates , and 28 select environmental isolates .
mlva , multiple - locus variable - number tandem repeat analysis ; paga , protective antigen gene ; pa , protective antigen ; , loci not detected ; na , not applicable .
allele size for each vntr locus is shown in addition to the mlva and pa genotypes .
no mlva genotype assigned due to the lack of one of the virulence plasmids ( pxo1 or pxo2 ) .
paga not present in pxo1-cured strains and thus could not be assigned a pa genotype .
was detected in the mail , we subtyped several isolates from cutaneous anthrax cases that occurred in the 1960s and 1970s in the eastern united states to determine if any were similar to the outbreak strain .
two isolates from rhode island were mlva genotype 71 , one new hampshire isolate was genotype 78 , while an additional new hampshire isolate and a massachusetts isolate each had unique combinations of alleles resulting in new genotypes .
the paga sequence of all five new england isolates was identified as pa genotype vi ( table 2 ) .
, the isolate was shown to have been cured of pxo1 and had the same genotype as the pasteur strain , used in laboratories as a control strain for various tests ( table 2 ) .
country b sent an isolate ( 2002007581 ) that was reportedly isolated from a letter to a private physician .
mlva identified the strain as genotype 45 , which clearly distinguished it from the strain associated with the ongoing outbreak in the united states .
in addition , four other isolates from the same facility were assayed by mlva ( 200200764851 ) , resulting in the identification of two sterne strains , one pasteur strain , and one additional strain of genotype 45 ( table 2 ) .
mlva and paga sequencing were performed on clinical specimens collected from seven patients with laboratory - confirmed inhalational anthrax during the 2001 bioterrorism - associated anthrax outbreak .
these methods have an unproven utility on clinical specimens , and further testing will be necessary for full evaluation .
a total of 28 clinical specimens were analyzed by using mlva , including : blood , csf , pleural fluid , serum , lung tissue , and lymph node tissue ( table 3 ) .
all eight loci were detected in three specimens ( two pleural fluids and one lymph node from patient 10 ) .
of the eight loci examined , vrra was detected in all nine specimens in which any of the mlva loci were detected and on two occasions was the only locus detected .
the paga gene was successfully amplified and sequenced from 5 of 22 specimens analyzed ( table 3 ) .
mlva , multiple - locus variable - number tandem repeat analysis ; paga , protective antigen gene ; lrn , laboratory response network ; pcr , polymerase chain reaction .
( 19 ) and patient 11 in barakat et al ( 20 ) specimens collected postmortem .
number of days the specimen was collected following or before the initiation of antimicrobial therapy .
specimens collected the same day as the initiation of therapy were designated as day 0 but were collected before antibiotic therapy
. results using the laboratory response network pcr assay for detection of b. anthracis during the outbreak ( 18 ) .
during the 2001 anthrax investigation , molecular subtyping of b. anthracis by mlva and paga sequencing was important in linking cases to each other and to contaminated sites and in distinguishing isolates that were not related to this event .
we used two methods for the molecular subtyping of b. anthracis : paga sequencing and mlva .
all outbreak - associated isolates were identified as mlva genotype 62 and pa genotype i. to date , mlva genotype 62 has only been associated with a few isolates from herbivores in texas and has not been identified in any b. anthracis strains originating in eastern united states or anywhere else in the world .
none of the new england isolates analyzed in this study were mlva genotype 62 or pa genotype i. all five were of pa genotype vi , while mlva identified two isolates as genotype 71 , one as genotype 78 , and two as new genotypes .
genotype 62 is also the genotype of the ames strain commonly used in research laboratories worldwide and frequently used in animal challenge studies ( 1116 ) . the sequence of paga from the outbreak strain , pa genotype i , was also identical to that of the ames strain ; thus , the outbreak b. anthracis strain is indistinguishable from the ames strain based on the examination of the eight mlva loci and the paga sequence .
recently , comparative genome sequencing detected only four differences between the chromosomes of the outbreak strain ( florida isolate ) and ames ( porton ) isolate ( 17 ) .
molecular subtyping of isolates immediately upon their arrival to the laboratory allowed for instant confirmation that the cases were caused by the same strain and thus for linking cases to environmental contamination and to the powder - containing envelopes . the speed of the mlva allowed for genotype identification within 8 hours of receiving the isolates .
in addition to linking the cases , molecular subtyping was invaluable in determining if b. anthracis , isolated from around the world during the same time period , were potentially related to the ongoing outbreak in the united states . the level of discrimination provided by mlva , allowed for non - outbreak isolates to be rapidly and easily distinguished . while both mlva and paga sequencing are primarily used for molecular subtyping of isolates , we were also able to amplify the eight mlva loci and paga directly from a limited number of available clinical specimens .
although this event was not a prospective case - control study , amplification was most successful from pleural fluid and lymph node specimens .
similar results were demonstrated with a b. anthracis specific real - time pcr assay ( 18 ) .
amplification of the mlva loci and paga was not very successful from blood cultures even when taken before antibiotic therapy .
the lack of success with blood cultures was not because of a complete inhibition of pcr since the b. anthracis lrn pcr assay was positive on these specimens .
of the mlva loci , vrra was the most readily amplified ( 9 of 28 ) , probably because vrra amplification is more sensitive compared to the other mlva loci .
however , limits of detection for each of the loci has not been evaluated . for a single patient ( patient 10 )
, we were able to amplify all eight mlva loci and determine the genotype of the b. anthracis strain without having the isolate itself .
in this instance , mlva was used directly on dna extracted from pleural fluid and genotype 62 was identified .
the paga gene was amplified and sequenced from the same dna specimen and identified as pa genotype i. mlva and paga amplification were attempted on dna extracted from blood drawn from this patient the same day as the pleural fluid but failed to detect any of the loci , suggesting more efficient clearance of the bacilli from the blood or less sensitivity of these molecular approaches on blood compared to pleural fluid .
again , the negative result on blood was not because of complete inhibition of pcr since the b. anthracis lrn pcr assay on this sample was positive . at a later date , when the centers for disease control and prevention received the isolate originally cultured from this patient at the local medical facility where the patient was treated , the isolate was confirmed to be genotype 62 . despite the fact that b. anthracis was not successfully cultured from any of these clinical specimens taken after the initiation of antimicrobial therapy
, we were able to amplify the mlva loci and paga from some of these specimens .
the entire chromosomal sequence of the b. anthracis ames strain ( available from : url : www.tigr.org ) is now available and has been compared to the chromosomal sequence of the outbreak ( florida ) isolate ( 17 ) .
while sequencing and comparing b. anthracis genomes are not likely to be useful for rapidly identifying isolates during an outbreak investigation , the data generated from such comparisons may identify new loci , which could be targets for methods such as mlva and can be done rapidly on large numbers of isolates from patients , the environment , and on dna from clinical specimens .
Output:
| molecular subtyping of bacillus anthracis played an important role in differentiating and identifying anthrax strains during the 2001 bioterrorism - associated outbreak . because b. anthracis has a low level of genetic variability , only a few subtyping methods , with varying reliability , exist .
we initially used multiple - locus variable - number tandem repeat analysis ( mlva ) to subtype 135 b. anthracis isolates associated with the outbreak .
all isolates were determined to be of genotype 62 , the same as the ames strain used in laboratories .
we sequenced the protective antigen gene ( paga ) from 42 representative outbreak isolates and determined they all had a paga sequence indistinguishable from the ames strain ( pa genotype i ) .
mlva and paga sequencing were also used on dna from clinical specimens , making subtyping b. anthracis possible without an isolate .
use of high - resolution molecular subtyping determined that all outbreak isolates were indistinguishable by the methods used and probably originated from a single source .
in addition , subtyping rapidly identified laboratory contaminants and non - outbreak related isolates . |
PubmedSumm118625 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: mature digestive cd8 tcell lymphomas are rare entities of variable severity ( from indolent to aggressive and destructive disease ) 1 , 2 , 3 . despite their severity
we report here an unusual case of severe mature cd8 tcell lymphoma with digestive infiltration that mimicked crohn 's disease , but with favorable outcome upon oral treatment with cyclophosphamide .
a 37yearold male with a history of pancolitis consistent with crohn 's disease was successively treated with azathioprine and antitumor necrosis factor ( tnf)alpha antibodies ( adalimumab and infliximab ) with limited results .
he developed persistent buccal ulcerations . examination of the oral cavity highlighted the presence of palatal and mucosal ulcerations with fibrin deposits , gingivitis , periodontitis , osteolysis , and total destruction of the uvula ( fig .
the patient was treated with mesalamine , methotrexate , and ustekinumab ( antiinterleukin 12 antibody ) , without longlasting effects .
diarrhea and oral ulcerations progressively worsened , leading to a weight loss of 8 kg .
multiple ulcerations , consistent with pancolitis , were found mainly in the right colon and cecum by endoscopic exploration of the digestive tract .
histopathological analysis of the palatal ulcerations showed a diffuse mucosal lymphoid infiltration made of small to mediumsized lymphoid cells ( fig .
conversely , they were negative for cd56 , epstein barrencoded small rnas ( ebers ) , and cd30 .
the proliferation index , assessed by ki67 staining , was low to moderate ( not shown ) .
review of historical colonic biopsies showed the same lymphoid mucosal infiltration with superficial ulcerations without crypt distortion and absence of granuloma .
clonal cd8 tcell expansion was assessed by tcell receptor locus rearrangement analysis and was detected in lymphoid cells from the oral cavity and colon ( fig .
1f ) , but not in blood . a computerized tomodensitometry of thorax and abdomen found no additional organ involvement .
no somatic stat3 exon 21 mutation was detected in this lymphoproliferative malignancy with expansion of mature and cd8 lymphoid cells 4 .
palate biopsy : dense lymphoid infiltrate beneath the normal epithelium and ulcerations with large amount of necrosis within the lymphoid infiltrate ( hematoxylin eosin [ he ] staining ; scale bar 700 ) ( b ) . detail of the infiltrate : small to mediumsized lymphoid cells ( he staining ; scale bar 60 ) ( c ) .
immunohistochemistry : lymphoid cells were positive for cd3 ( d ) and cd8 ( e ) ( scale bar 150 ) .
tcell receptor locus rearrangement analysis of colon lymphoid cells showing that the cd8 tcell expansion was clonal ( f ) .
on the basis of the diagnosis of mature cd8 tcell lymphoproliferative disorder , oral treatment with 150 mg cyclophosphamide per day was started .
after 4 months , the patient had already recovered his baseline weight and the oral cavity lesions had completely healed ( fig .
we report a very unusual case of mature cd8 tcell lymphoma with digestive infiltration that mimics crohn 's disease .
our finding suggests that in patients with atypical features of crohn 's disease , including severe oral ulcerations , and who are refractory to standard treatment , the alternative diagnosis of clonal cd8 tcell lymphoproliferative disorder should be considered
. its prognosis can be remarkably favorable upon oral treatment with cyclophosphamide , as observed for our patient .
Output:
| key clinical messagein patients with atypical crohn 's disease features , including severe oral ulcerations and resistance to standard treatment , the possibility of a mature clonal cd8 + tcell lymphoproliferative disorder should be investigated .
clinicians should be aware of this differential diagnosis because cd8 + tcell lymphoma prognosis can be remarkably favorable upon oral treatment with cyclophosphamide . |
PubmedSumm118626 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: changes in balance , mobility , and muscle strength are associated with aging and interfere
with performance of activities of daily living and functional capacity .
functional
activities such as walking remain critical in the elderly population because of loss of
mobility and muscle strength , which may increase the risk of falls1,2,3 .
muscle strength starts to decrease early in the life span , with losses of about 1215% per
decade after 50 years of age4 , and this
figure might be as high as 50% in people above 80 years of age3 .
the importance of balance , mobility , and muscle strength to
maintenance of functional capacity within the complex scenario of aging is already
known5 .
the older population may present
with functional impairment earlier than 70 years of age because of the decline in different
physical aspects .
the decrease in temporal nature of many intricate physical aspects during
the aging process needs to be identified as soon as possible to avoid important functional
losses .
knowledge concerning the functional profiles of age - stratified groups of elderly people
would provide a better approach to the maintenance of functionality and the prevention of
falls and functional dependency through public health programs .
we intended to
achieve this by comparing physical performance , balance , mobility , and muscle strength in
age - stratified groups of elderly people .
the study included 152 ( 56 men , 96 women ) participants ranging from 60 to 96 years of age .
the inclusion criteria were
subjects who were 60 years of age or older ; had a minimum score of 18 on the mini - mental
state examination ( mmse ) , indicating normal cognitive status6 and had the capability to walk with or without any support
accessories such as a cane or walker , excluding wheelchairs .
the participants were recruited at the
physiotherapy and geriatrics outpatient facility , hospital das clnicas da faculdade de
medicina da usp and were divided into 3 age - stratified groups : g1 ( 60 to 69 years ) , g2 ( 70
to 79 years ) , and g3 ( 80 years or older ) . the same trained professional collected data from
the participants for the clinical and sociodemographic characterization and performed all
the assessments for each participant in the same sequence as bellow , with no time interval
between them , taking from 25 to 45 minutes per participant .
this cross - sectional ,
exploratory and descriptive study was approved by the local ethics committee , comisso de
tica para anlise de projetos de pesquisa do hcfmusp ( cappesq , 0968/2007 ) .
assessment of physical performance the short physical performance battery ( sppb ) was used
to evaluate the static balance when standing , gait speed at a regular pace , and a movement
consisting of sitting down and standing up7 .
performance was measured by the time spent during each test , with
scores ranging from 0 to 4 . the total score on the sppb
is obtained by adding together the
scores of each test ; it ranged from 0 ( the worst performance ) to 12 points ( the best
performance ) .
assessment of mobility the timed up and go ( tug ) test was used to assess functional
mobility and dynamic function8 .
an
execution time of 10 seconds is assumed as the standard performance , while a time between 11
and 20 seconds indicates frailness or disability and a time of over 20 seconds indicates an
important mobility injury .
assessment of balance the berg balance scale ( berg ) was used to evaluate static and
dynamic functional balance , with high specificity to predict people with an increased risk
of falling by means of a scale of 14 items associated with specific functional tasks9 .
the total score ranges from 0 to 56 points ,
representing the range of worst to best performance respectively .
assessment of lower limb muscle strength leg press equipment was used to determine the
maximum muscle strength using the one - repetition maximum ( 1-rm ) for triple extension of the
lower limbs .
the test was performed by progressive raising of load , beginning with
approximately 50% of the load that would be used in the first attempt . the participant
needed to perform the complete range of extension of the lower limb with no hyperextension
of the knee to qualify the attempt . for each load tested , 3 qualified attempts were required
to determine the load corresponding to the 1-rm .
the minitab 15.1 software ( minitab , state college , pa , usa ) was used to perform statistical
analysis .
descriptive analysis was performed to characterize the 3 groups . to determine the
differences between groups and gender , two - factor ( group and gender ) analysis of variance
with tukey s test as a post hoc test or , when appropriate
, the kruskal - wallis test with
bonferroni correction was used to compare the 6 subgroups comprised of the 3 original
age - stratified groups ( g1 , g2 and g3 ) divided by gender .
the clinical and sociodemographic characteristic of the studied population are shown in
table 1table 1 .
the sociodemographic and clinical data of the study population ( n=152 ) by age
groupgroupscharacteristics g1 ( n=53)g2 ( n=65)g3 ( n=34)gender n ( % ) female31 ( 58.5)42 ( 64.6)23 ( 67.6)male22 ( 41.5)23 ( 35.4)11 ( 32.4)anthropometric data ( meanstandard deviation)weight ( kg)71.213.368.313.060.311.8height ( cm)161.69.4156.49.5153.46.2bmi ( kg / cm)27.24.127.94.925.54.2marital status ( % ) single11.37.714.7married73.646.220.6widower15.144.658.8divorced-1.55.9schooling ( % ) illiterate1.96.2 - 1 to 7 years of study28.343.158.88 years of study15.112.317.69 to 10 years of study3.8 - 5.911 years of study18.910.82.9 > 11 years of study32.127.714.7comorbiditiesnumber of diseases3.11.93.72.13.52.1number of drugs3.42.84.94.14.92.9number of hospital admissions0.10.30.20.50.30.8falls ( meansd)number of falls 0.71.11.01.21.51.7 .
female participants were predominant in the 3 groups ( g1=31 male , 53 female
[ 58.49% ] ; g2=42 male , 65 female [ 64.61% ] ; g3=23 male , 34 female [ 67.64% ] ) . the descriptive
statistics of the tests are shown in table
2table 2 .
descriptive statistics of the sppb , berg , tug , and leg press teststestgroupgendermedian ( min - max)mean ( sd)sppbg1f11 ( 012)m11.5 ( 612)g2f11 ( 1012)m12 ( 712)g3**f9 ( 612)m12 ( 712)bergg1f56 ( 5056)m56 ( 3056)g2f52.5 ( 2956)m55 ( 4456)g3f47 ( 4756)m51 ( 4056)tug*g19.03 ( 0.31)g29.94 ( 2.67)g313.67 ( 6.79)leg press*g174.15 ( 25.41)g261.38 ( 24.30)g339.41 ( 21.12 ) * no interaction between group by gender , p>0.6 ; * * p=0.027 .
* no interaction between group by gender , p>0.6 ; * * p=0.027 comparison by gender for the entire population ( g1 , g2 , and g3 ) using kruskal - wallis test
showed differences in sppb and berg distributions ( sppb , p=0.016 ; berg , p=0.030 ) .
pairwise
comparisons after bonferroni correction showed differences between g1 and g3 ( sppb , p=0.001 ;
berg , p=0.009 ) and g2 and g3 ( sppb , p=0.001 ; berg , p=0.009 ) for women .
analysis of variance of leg press and square root of tug scores showed the effect of group
( tug , p=0.002 ; leg press , p<0.001 ) and gender ( leg press , p<0.001 ) .
as no interactions
between group by gender ( tug , p=0.494 ; leg press , p=0.556 ) were found , pairwise comparisons
among levels of group were performed and showed that tug scores decreased in comparisons
between g1 and g3 ( tug , p=0.001 ; leg press , p<0.001 ) and between g2 and g3 ( tug , p=0.020 ;
leg press , p=0.008 ) .
this study aimed to compare physical performance , balance , mobility , and muscle strength
among 152 elderly volunteers from 60 to 96 years old divided in age - stratified groups .
we
used the sppb , berg , tug test , and leg press test to compare elderly people at their 60s ,
70s and above 80s .
the assessments were compared by gender for the entire population , and
pairwise comparisons were used to show differences between groups .
the results of our study showed that elderly people in their 60s and 70s had similar
functional characteristics ( physical performance , balance , mobility , and muscle strength )
for both genders and that these characteristics started to decline in the elderly people in
their 80s .
the aging process leads to sarcopenia , with affects about 13 to 24% of elderly
people in their 60s and 70s and more than 50% of the elderly in their 80s11 .
these alterations of muscle tissues were
associated with muscle stiffness , poor muscle recruitment , compromised balance , and
compromised functional capacity12 , 13 .
the prevalence of falls among elderly
people in their 80s in brazil is higher than for elderly people in their 60s and 70s which
may be caused by the decline in functionality14 .
prevention programs have shown a positive impact on maintenance of
functionality , and the practice of getting regular physical activity promotes physical
fitness , functional autonomy , and healthy aging15 ,
16 .
the results of our study highlight
the importance of applying specific programs to motivate elderly people in their 70s and 80s
to become physically active and delay functional losses . women in their 70s show a significant decline in functionality ( physical performance and
balance ) compared with men of the same age .
elderly women display greater loss of muscle
mass and muscle strength , and these losses predispose women to develop frailty syndrome .
furthermore , there are more elderly women worldwide than men , and the physical disabilities
occur frequently in women17 .
thus , women
have a higher life expectancy than men and are predisposed to losing the protective factor
of social support for the prevention of functional and psychological disability .
this study addressed important issues concerning physical decline to alert health
professionals about the need for attention in prevention programs for elderly people .
the
practice of regular physical activity improves the level physical activity and helps elderly
people to maintain and/or improve functional capacity , thus enabling healthy aging .
it is recommended
that further multidisciplinary studies be undertaken to check other components such as
psychological issues .
it
is unknown if elderly people in their 60s and 70s have similar functional characteristics
( physical performance , balance , mobility , and muscle strength for both genders ) due to
performance of exercises or not .
future studies are needed to verify the influence of
physical activities among age - stratified groups of elderly people .
Output:
| [ purpose ] the aim of this study was to verify the decline in functionality of elderly
people . [ subjects and methods ] the study subjects comprised 152 individuals ( 96 women ; 56
men ) divided into 3 groups : g1 ( 60 to 69 years , n=53 ) ; g2 ( 70 to 79 years , n=65 ) ; and g3
( 80 years or older , n=34 ) .
physical performance , balance , mobility , and muscle strength
were assessed using short physical performance battery ( sppb ) , berg balance scale ( berg ) ,
timed up and go ( tug ) test , and leg press test , respectively .
comparison among
age - stratified groups ( g1 , g2 and g3 ) and between genders were examined using analysis of
variance with tukey s test as a post hoc test or the kruskal - wallis test with bonferroni
correction .
[ results ] sppb and berg scores decreased significantly in comparison between
g1 and g3 , and between g2 and g3 in women .
tug and leg press scores decreased
significantly in comparison between g1 and g3 and between g2 and g3 .
[ conclusion ] people
in their 60s and 70s have similar functional characteristics ( physical performance ,
balance , mobility and muscle strength for both genders ) , and functionality starts to
decline when people are in their 80s . |
PubmedSumm118627 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: a 23-year - old girl was admitted to hospital with sudden onset of loss of vision in both her eyes .
studying the details of the patient 's history revealed episodes of weakness and dizziness since two years ago .
she also experienced temporary clouding of sensorium and falling down on several occasions especially in the upright position just after a slight physical activity .
, physical examination revealed an oral temperature of 37.2c , a heart rate of 100 beats per minute , a respiratory rate of 18 breaths per minute , blood pressure in right upper arm was 150/100 mmhg and in left upper arm 170/100 mmhg , very weak pulses of the upper extremities and normal pulses of the lower ones . in neurological examination ,
mri of the brain with contrast agent showed bilateral abnormal t2 signals in white matter .
visual evoked potential ( vep ) showed prolonged p100 latency in both eyes and electroencephalography ( eeg ) was reported normal .
optic neuritis ( on ) caused by multiple sclerosis ( ms ) was diagnosed and she received iv methyprednisolone 1 gr / day for 3 days .
her vision became better but attention on history of dizzy spell , physical findings of very weak pulses of upper limbs and difference between blood pressure of left and right arms made us investigate more on it .
radiological and sonographic findings of patient are listed in table 2 . as noted in table 2 ,
ct and conventional angiographies of chest and cervical arteries were the most diagnostic ones ( figure 1 ) .
hematological findings of patient radiological and sonographic findings of patient ct angiography of aortic arch and cervical vessels of the patient showed extensive stenosis of more cervical vessels , aneurismal dilation of inominate artery so diagnosis of ta was established and due to rheumatologic consultation , she received 1 gr / day iv methyprednisolone for 5 days , 500 mg iv cyclophosphamide in the next day and oral antiplatelet clopidogrel bisulphate ( plavix 75 mg / day ) .
this patient was a candidate for the stenting of the right vertebral artery which was recommended by an interventional cardiologist .
two months later , the successful stenting of the right vertebral artery was done ( figures 2 and 3 ) and the patient was discharged from hospital with good general condition .
one week later , she developed a very severe headache , repeated seizures and loss of consciousness .
ventriculoperitoneal shunt was inserted for her , but it was unsuccessful and she passed away after a few days .
stenting of right vertebral artery in the patient stenting of right vertebral artery in the patient
takayasu arteritis is an inflammatory aortitis which mainly affects young females in the age group of 10 - 30 years510 ; its male to female ratio is 1 to 8.5.11 it is more prevalent in asians , but it has a widespread distribution.51213 the occurrence of neurological manifestations was reported in 52.7% of patients with ta.26 headache was the most common symptom ( 55%).6 major neurological events occurred in about one - half of the patients were tia , cerebral infarction , hypertensive encephalopathy , seizure , paraplegia and even moya - moya phenomenon.614 these events are related to a combination of carotid and vertebral artery disease and the complication of hypertension and thromboembolism would lead to stroke.27 differential diagnosis of ta are other causes of large vessels vasculitis including infectious aoritis ( syphilis , mycobacterial , fungal ) , autoimmune causes ( systemic lupus , behcet 's disease , giant - cell arteritis and kawasaki disease ) and some developmental abnormalities ( coartation of aorta and marfan 's syndrome),2515 most of which have clinical presentation or specific laboratory findings , however , they were not found in our patient .
although sarcoidosis may have clinical and radiological presentation similar to ta,15 lack of some specific features such as skin lesion and hilar lymphadenopathy ruled it out .
diagnosis of ta needs at least 3 of 6 criteria of the american college of rheumatology ( table 3).9 our patient 's criteria were being 23 years old , having pulseless arms , having different blood pressure between two arms ( 20 mmhg ) and arteriographic findings of stenosis in aortic arc with its main branches ( tables 1 and 2 ) .
the presence of 3 or more of these 6 criteria demonstrates 90.5% and 97.8% sensitivity and specificity , respectively.9 the american college of rheumatology criterions for the diagnosis of takayasu arteritis 9 optic neuritis caused by ms was a misdiagnosis in our patient and combinations of visual loss , abnormal veps , and white matter signals of mri were misleading .
mri criteria of mcdonald supports clinically definite diagnosis of ms16 which needs evidences of at least two episodes of neurological deficits and physical findings of two sites involving in central nervous system
. however , pulsetherapy by methylprednisolone is the best treatment of optic neuritis . in our patient ,
two main arterial systems of central nervous system ( vertebrals and carotids ) were involved .
abnormal white matter t2 signals of mri were ischemia in watershed zones secondary to severe hypoperfusion in carotids and vertebral arteries circulation .
classical ophthalmic features of ta are because of the reduced ocular perfusion.2 the occlusion of retinal artery branches has also been reported.17 anterior ischemic optic neuropathy ( aion ) is rare in ta.12 treatment of ta is divided into medical and surgical or endovascular therapy .
second - line drugs , including cyclophosphamide , azathioprine and methotrexate , should be taken in refractory cases or in patients with recurrence of disease activity.25 antiplatelet or anticoagulant agents prevent thromboembolic events
. surgical or endovascular therapy of ta has been performed in critical stenosis of renal , coronary or cerebral vessels .
clinical features of cerebrovascular ischaemia or critical stenosis of at least three cerebral vessels need interventional procedures.2 although angioplasty is not successful in total occlusions , using it opens shortsegment occlusions.18 in spite of high initial success rate of angioplasty in ta , there are some different reports on long - term restenosis rate.1920 our patient was treated by iv methylprednisolone , cyclophosphamide and oral clopidogrel
. it seemed that performing angioplasty with stenting of right vertebral artery as the only perfusing brain vessel was lifesaving .
we did it but she passed away after stenting and it might be because of sah resulting from hyperperfusion phenomenon .
some studies reported that it may have unusual neurologic presentations such as seizure , myelitis , and pres .
our patient with hyperintense white matter lesions in brain mri and vision loss was found as an example of ta which simulates ms .
na carried out the design , coordinated the study , participated in most of the experiments and prepared the manuscript .
Output:
| neurological manifestation may complicate takayasu arteritis ( ta ) . a 23-year - old girl with sudden onset of vision loss
was admitted to hospital .
her brain mri showed abnormal t2-signal hyperintensity and visual evoked potential revealed prolonged p100 latency .
consequently , optic neuritis was diagnosed .
a review on history of dizziness , falling , and weak pulses of upper extremities led to more investigation .
angiography revealed a total occlusion of right and left carotids , left vertebral arteries , aneurismal dilatation of innominate artery and critical stenosis of right vertebral artery .
following diagnosis of ta , stenting of right vertebral artery was done , but she passed away because of subarachnoid hemorrhage . |
PubmedSumm118628 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: dry eye disease ( ded ) is a medical condition associated with symptoms of ocular irritation , visual disturbance , and tear film instability , often going hand in hand with ocular surface damage and inflammation .
dry eye is considered a multifactorial disease with numerous causes and risk factors.1 some clinicians may differentiate ded into an aqueous deficient type ( aqueous deficient de ) or an evaporative type ( evaporative de ) , although most of the time , the distinction is not that clear . however , whether aqueous deficient or evaporative , both can result in a cycle of inflammation , tear hyperosmolarity , and ocular surface damage.1 inflammation has a key role in ded and is both a result and cause of tear deficiency and ocular surface damage .
although common , diagnosis and clinical evaluation of dry eye typically rely on patient symptoms and clinician s subjective grading of ocular surface staining patterns .
monitoring of treatment efficacy is mostly dependent on improvement of patient symptoms , as well as signs of ocular surface damage.1,2 the conjunctival epithelium has an important role in the ocular surface defense mechanism . aside from it being an anatomical barrier to the external environment
, the conjunctival epithelium has the ability to build up an inflammatory response by promoting leukocyte migration by expressing cell adhesion molecules , such as intercellular adhesion molecule 1 , and major histocompatibility complex ii molecules , such as human leukocyte antigen d - related ( hla - dr ) , on antigen - presenting cells .
hla - dr plays an important role in t - cell activation and is overexpressed in many patients with ded.37 hla - dr expression on surface cells has been shown to correlate with inflammation and was found to be increased in patients with dry eye .
flow cytometric analysis of samples taken from the ocular surface by impression cytology that appropriately stained may be used to detect this proinflammatory marker.814 because hla - dr is considered a biomarker for the increased inflammation on the ocular surface associated with ded , detection of hla - dr by flow cytometric analysis may be a useful indicator for identifying ongoing inflammatory processes , classifying the severity of ded , and evaluating the response to treatment . therefore , the relative percentage of cells obtained from impression cytology , which highly express hla - dr , may provide a minimally invasive objective measure of inflammation of the ocular surface .
the test treatment used in this study was a lubricant eyedrop product containing polyethylene glycol ( peg ) , propylene glycol ( pg ) , and hydroxypropyl guar ( hp - guar ) preserved with polyquaternium-1 ( polyquad ) .
the preservative polyquaternium-1 has been shown in animal studies to be less toxic to the ocular surface than the traditional preservative benzalkonium chloride.1519 hp - guar effectively relieves signs and symptoms related to moderate dry eye , with measurable improvements evident in both objective staining and subjective questionnaire.19 the purpose of this study was to evaluate the efficacy of this lubricant eyedrop solution in improving signs and symptoms of ded , as well as its influence on surface inflammatory markers measured by flow cytometry .
this was a single - arm , open - label study of an over - the - counter lubricant eyedrop with active ingredient peg / pg + hp - guar ( www.clinicaltrials.gov identifier , nct00946777 ) .
this institutional review board - approved trial was conducted in accordance with the good clinical practice guidelines for the evaluation of medical products and following the tenets of the declaration of helsinki .
patients were selected from those being seen at the faculty practice associates at the department of ophthalmology , mount sinai school of medicine .
nineteen patients who were diagnosed with mild to moderate ded with typical signs and symptoms were recruited .
all patients read , understood , and signed the informed consent form before any examination was obtained .
male as well as female patients who were 18 years of age or older were eligible for the study .
the major inclusion criteria were at least one symptom of dry eye that was graded moderate to severe ( rated on a 4-point scale ) or clinical evidence of dry eye by schirmer testing ( < 10 mm/5 min ) .
patients were required to show evidence of ocular surface disease , moderate vital staining of the ocular surface with fluorescein ( for corneal evaluation ) and lissamine ( for conjunctival evaluation ) , and had to be willing to discontinue current eye medications , use peg / pg + hp - guar four times a day , and return on follow - up dates throughout the course of the study .
patients with any of the following were excluded from the study : uncontrolled systemic ( ie , diabetes mellitus , rheumatoid arthritis , and other immunologic or autoimmune diseases ) or ocular disease ( ie , glaucoma or uveitis ) , dry eye due to seasonal allergic conjunctivitis , contact lens - related conjunctivitis or other acute or seasonal diagnoses , monocular and/or legal blindness , history of ocular surgery or trauma within the last 6 months , or participation in an ophthalmic drug or device research trial within 30 days before entry in this study .
us food and drug administration - approved over - the - counter lubricant eyedrops were used in this study .
the test solution was a peg / pg - based , hp - guar containing lubricant eyedrop , preserved with polyquad ( systane ultra lubricant eye drops , alcon laboratories , inc . , fort worth , tx , usa ) .
after the study was explained and consent given , eligibility criteria were assessed to ensure all patients had dry eye signs and symptoms .
after baseline screening and baseline impression cytology , all 19 patients were instructed to discontinue other artificial tear products but could continue use of restasis ( cyclosporine a ; allergan , inc . , irvine , ca , usa ) if they had been using it for at least 6 months , because baseline readings may change significantly if chronic usage was discontinued .
they were given peg / pg + hp - guar , to be used four times per day to both eyes for 1 month .
at the end of 1 month , clinical assessments were performed to compare before and after treatment .
samples taken by impression cytology were analyzed by a masked examiner , using flow cytometry .
inflammatory markers ( percent cells highly expressing hla - dr ) before and after study treatment were determined .
cells were collected via the technique adapted from previously established methods.4,8,12 in brief , after administration of a single drop of topical anesthetic ( 0.5% proparacaine hydrochloride ophthalmic solution ) , two sterile 0.20-m , 13-mm polyether sulfone filter membranes ( supor-6-membranes , pall life sciences , ann arbor , mi , usa ) were applied bilaterally onto the superior bulbar and supero - temporal aspects of the conjunctiva without applying pressure , at least 15 minutes after any prior ophthalmic procedure(s ) .
cells were collected in a sterile fashion and placed in 2 ml paraformaldehyde ( 0.05% in phosphate - buffered saline [ pbs ; mediatech inc , manassas , va , usa ] ) in 5 ml , 12 mm 75 mm test tubes ( bd biosciences , franklin lakes , nj , usa ) for direct immunofluorescence and subsequent cell cytology . all specimens from a given eye were placed into a single test tube .
one to two drops of prophylactic antibiotics ( 0.5% moxifloxacin hydrochloride ) were administered to both eyes after collection .
the percentage of highly hla - dr positive ( inflammatory ) cells was calculated by direct immunofluorescent staining followed by cell cytology.4,8,12 in brief , upon initiation of staining , the samples were diluted with 2 ml cold ( 4c8c ) 0.5% bovine serum albumin ( bsa ) in pbs .
cells were separated from the filters by mechanical agitation ( vortex ; 15 seconds ) followed by centrifugation at 1,600 rpm for 5 minutes ( 4c ; beckman gs 6r centrifuge , beckman coulter , inc , fullerton , ca , usa ) . the filters were removed , the cells resuspended ( 0.5% bsa in pbs ) , and 40% of the resulting samples split into new test tubes to be used as negative controls .
the cells of all tubes were concentrated by recentrifugation ( 1,600 rpm , 5 minutes , 4c ) followed by decanting and resuspension in 200 l ( 0.5% bsa in pbs ) .
fluorescein isothiocyanate- conjugated monoclonal mouse antihuman hla - dr , alpha chain clone , tal.1b5 antibody ( bd biosciences ) and fluorescein isothiocyanate - conjugated mouse antihuman igg2b ( negative isotypic control ; bd biosciences ) were diluted 1:50 in 0.5% bsa in pbs and were incubated with samples at 4c in the dark .
samples were washed ( 0.5% bsa in pbs ) twice after centrifugation ( 1,600 rpm 5 minutes , 4c ) and resuspended in 400 l bsa ( 0.5% ) in pbs in preparation for flow cytometry.4,8,12 after immunostaining , cells in the resulting solutions were analyzed by flow cytometry ( facs - calibur , bd biosciences ) , equipped with an argon ion laser , which emits at 488 nm .
preliminary calibrations were made using immortalized conjunctival epithelium ( clone 1 - 5c-4 [ wong - kilbourne derivative ( d ) of chang conjunctiva ] , atcc , ccl-20.2)20,21 as the negative control22 and htk - h cells ( human corneal fibroblast cell line)23 as the positive control for hla - dr staining .
to analyze , dot plots for cell size ( forward scatter ) versus cellular granularity ( side scatter ) and fluorescence channel ( fl ) 1 versus cellular granularity ( side scatter ) and a histogram ( fl1 versus event count ) were plotted , demonstrating a single homogenous cell population ( figure 1 ) .
analytic gates were set around the area of interest to exclude cellular debris and aggregates . the percentage of hla - dr positive cells was obtained from a cytogram , yielding the histogram s statistics , indicating the mean intensity of cell fluorescein that was proportional to hla - dr expression . in each sample ,
samples from each eye were analyzed separately and independently.8,9,1114 all specimens were processed by a masked observer .
clinical assessments included the ocular surface disease index ( osdi ) questionnaire , tear film break - up time ( tfbut ) , corneal and conjunctival staining with fluorescein and lissamine , and schirmer testing with anesthesia.2427 the osdi questionnaire was completed following the standard technique by stevenson et al.27 standardized tfbut was done by instillation of 5 l of 2% fluorescein onto the conjunctival fornices and recording the time for the tear film to break up on the corneal surface .
corneal staining was then assessed using the national eye institute scale for grading , dividing the corneal surface into five areas and scoring accordingly ( grade of 015 per eye).2426 conjunctival staining was evaluated using lissamine - impregnated strips wetted with artificial tears , and conjunctival staining pattern was graded according to density , using a scale of 03 on both the nasal and temporal conjunctiva ( grade of 06 per eye).24,25 impression cytology was then performed using the technique described earlier .
schirmer testing with anesthesia was performed by instilling anesthetic drops onto the lower conjunctival fornices , then waiting for 3 minutes before placing the tear strips on the lower lid margin .
patients were asked to close their eyes for 5 minutes before taking the readings.24 the modified dry eye workshop ( dews ) score was graded based on the aforementioned tests and clinical evaluation mentioned .
the patients were then given a dews classification of ded severity ( table 1 ) , where scores from individual dry eye test were replaced with severity grading score of 14.24 visual acuity , intraocular pressure measurement , and slit lamp biomicroscopy were also done as part of safety parameters .
statistical analysis was performed using spss ( ibm corporation , armonk , ny , usa ) and ncss ( ncss , llc , kayesville , ut , usa ) . within - patient , before and after treatment comparisons were conducted using paired t - tests .
this was a single - arm , open - label study of an over - the - counter lubricant eyedrop with active ingredient peg / pg + hp - guar ( www.clinicaltrials.gov identifier , nct00946777 ) .
this institutional review board - approved trial was conducted in accordance with the good clinical practice guidelines for the evaluation of medical products and following the tenets of the declaration of helsinki .
patients were selected from those being seen at the faculty practice associates at the department of ophthalmology , mount sinai school of medicine .
nineteen patients who were diagnosed with mild to moderate ded with typical signs and symptoms were recruited .
all patients read , understood , and signed the informed consent form before any examination was obtained .
male as well as female patients who were 18 years of age or older were eligible for the study .
the major inclusion criteria were at least one symptom of dry eye that was graded moderate to severe ( rated on a 4-point scale ) or clinical evidence of dry eye by schirmer testing ( < 10 mm/5 min ) .
patients were required to show evidence of ocular surface disease , moderate vital staining of the ocular surface with fluorescein ( for corneal evaluation ) and lissamine ( for conjunctival evaluation ) , and had to be willing to discontinue current eye medications , use peg / pg + hp - guar four times a day , and return on follow - up dates throughout the course of the study .
patients with any of the following were excluded from the study : uncontrolled systemic ( ie , diabetes mellitus , rheumatoid arthritis , and other immunologic or autoimmune diseases ) or ocular disease ( ie , glaucoma or uveitis ) , dry eye due to seasonal allergic conjunctivitis , contact lens - related conjunctivitis or other acute or seasonal diagnoses , monocular and/or legal blindness , history of ocular surgery or trauma within the last 6 months , or participation in an ophthalmic drug or device research trial within 30 days before entry in this study .
us food and drug administration - approved over - the - counter lubricant eyedrops were used in this study .
the test solution was a peg / pg - based , hp - guar containing lubricant eyedrop , preserved with polyquad ( systane ultra lubricant eye drops , alcon laboratories , inc . , fort worth , tx , usa ) .
after the study was explained and consent given , eligibility criteria were assessed to ensure all patients had dry eye signs and symptoms . after baseline screening and baseline impression cytology ,
all 19 patients were instructed to discontinue other artificial tear products but could continue use of restasis ( cyclosporine a ; allergan , inc . , irvine , ca , usa ) if they had been using it for at least 6 months , because baseline readings may change significantly if chronic usage was discontinued .
they were given peg / pg + hp - guar , to be used four times per day to both eyes for 1 month . at the end of 1 month , clinical assessments were performed to compare before and after treatment .
samples taken by impression cytology were analyzed by a masked examiner , using flow cytometry .
inflammatory markers ( percent cells highly expressing hla - dr ) before and after study treatment were determined .
cells were collected via the technique adapted from previously established methods.4,8,12 in brief , after administration of a single drop of topical anesthetic ( 0.5% proparacaine hydrochloride ophthalmic solution ) , two sterile 0.20-m , 13-mm polyether sulfone filter membranes ( supor-6-membranes , pall life sciences , ann arbor , mi , usa ) were applied bilaterally onto the superior bulbar and supero - temporal aspects of the conjunctiva without applying pressure , at least 15 minutes after any prior ophthalmic procedure(s ) .
cells were collected in a sterile fashion and placed in 2 ml paraformaldehyde ( 0.05% in phosphate - buffered saline [ pbs ; mediatech inc , manassas , va , usa ] ) in 5 ml , 12 mm 75 mm test tubes ( bd biosciences , franklin lakes , nj , usa ) for direct immunofluorescence and subsequent cell cytology . all specimens from a given eye were placed into a single test tube .
one to two drops of prophylactic antibiotics ( 0.5% moxifloxacin hydrochloride ) were administered to both eyes after collection .
the percentage of highly hla - dr positive ( inflammatory ) cells was calculated by direct immunofluorescent staining followed by cell cytology.4,8,12 in brief , upon initiation of staining , the samples were diluted with 2 ml cold ( 4c8c ) 0.5% bovine serum albumin ( bsa ) in pbs .
cells were separated from the filters by mechanical agitation ( vortex ; 15 seconds ) followed by centrifugation at 1,600 rpm for 5 minutes ( 4c ; beckman gs 6r centrifuge , beckman coulter , inc , fullerton , ca , usa ) .
the filters were removed , the cells resuspended ( 0.5% bsa in pbs ) , and 40% of the resulting samples split into new test tubes to be used as negative controls .
the cells of all tubes were concentrated by recentrifugation ( 1,600 rpm , 5 minutes , 4c ) followed by decanting and resuspension in 200 l ( 0.5% bsa in pbs ) .
fluorescein isothiocyanate- conjugated monoclonal mouse antihuman hla - dr , alpha chain clone , tal.1b5 antibody ( bd biosciences ) and fluorescein isothiocyanate - conjugated mouse antihuman igg2b ( negative isotypic control ; bd biosciences ) were diluted 1:50 in 0.5% bsa in pbs and were incubated with samples at 4c in the dark .
samples were washed ( 0.5% bsa in pbs ) twice after centrifugation ( 1,600 rpm 5 minutes , 4c ) and resuspended in 400 l bsa ( 0.5% ) in pbs in preparation for flow cytometry.4,8,12 after immunostaining , cells in the resulting solutions were analyzed by flow cytometry ( facs - calibur , bd biosciences ) , equipped with an argon ion laser , which emits at 488 nm .
preliminary calibrations were made using immortalized conjunctival epithelium ( clone 1 - 5c-4 [ wong - kilbourne derivative ( d ) of chang conjunctiva ] , atcc , ccl-20.2)20,21 as the negative control22 and htk - h cells ( human corneal fibroblast cell line)23 as the positive control for hla - dr staining .
to analyze , dot plots for cell size ( forward scatter ) versus cellular granularity ( side scatter ) and fluorescence channel ( fl ) 1 versus cellular granularity ( side scatter ) and a histogram ( fl1 versus event count ) were plotted , demonstrating a single homogenous cell population ( figure 1 ) .
analytic gates were set around the area of interest to exclude cellular debris and aggregates . the percentage of hla - dr positive cells was obtained from a cytogram , yielding the histogram s statistics , indicating the mean intensity of cell fluorescein that was proportional to hla - dr expression . in each sample ,
samples from each eye were analyzed separately and independently.8,9,1114 all specimens were processed by a masked observer .
cells were collected via the technique adapted from previously established methods.4,8,12 in brief , after administration of a single drop of topical anesthetic ( 0.5% proparacaine hydrochloride ophthalmic solution ) , two sterile 0.20-m , 13-mm polyether sulfone filter membranes ( supor-6-membranes , pall life sciences , ann arbor , mi , usa ) were applied bilaterally onto the superior bulbar and supero - temporal aspects of the conjunctiva without applying pressure , at least 15 minutes after any prior ophthalmic procedure(s ) .
cells were collected in a sterile fashion and placed in 2 ml paraformaldehyde ( 0.05% in phosphate - buffered saline [ pbs ; mediatech inc , manassas , va , usa ] ) in 5 ml , 12 mm 75 mm test tubes ( bd biosciences , franklin lakes , nj , usa ) for direct immunofluorescence and subsequent cell cytology . all specimens from a given eye were placed into a single test tube .
one to two drops of prophylactic antibiotics ( 0.5% moxifloxacin hydrochloride ) were administered to both eyes after collection .
the percentage of highly hla - dr positive ( inflammatory ) cells was calculated by direct immunofluorescent staining followed by cell cytology.4,8,12 in brief , upon initiation of staining , the samples were diluted with 2 ml cold ( 4c8c ) 0.5% bovine serum albumin ( bsa ) in pbs .
cells were separated from the filters by mechanical agitation ( vortex ; 15 seconds ) followed by centrifugation at 1,600 rpm for 5 minutes ( 4c ; beckman gs 6r centrifuge , beckman coulter , inc , fullerton , ca , usa ) .
the filters were removed , the cells resuspended ( 0.5% bsa in pbs ) , and 40% of the resulting samples split into new test tubes to be used as negative controls .
the cells of all tubes were concentrated by recentrifugation ( 1,600 rpm , 5 minutes , 4c ) followed by decanting and resuspension in 200 l ( 0.5% bsa in pbs ) .
fluorescein isothiocyanate- conjugated monoclonal mouse antihuman hla - dr , alpha chain clone , tal.1b5 antibody ( bd biosciences ) and fluorescein isothiocyanate - conjugated mouse antihuman igg2b ( negative isotypic control ; bd biosciences ) were diluted 1:50 in 0.5% bsa in pbs and were incubated with samples at 4c in the dark .
samples were washed ( 0.5% bsa in pbs ) twice after centrifugation ( 1,600 rpm 5 minutes , 4c ) and resuspended in 400 l bsa ( 0.5% ) in pbs in preparation for flow cytometry.4,8,12
after immunostaining , cells in the resulting solutions were analyzed by flow cytometry ( facs - calibur , bd biosciences ) , equipped with an argon ion laser , which emits at 488 nm .
preliminary calibrations were made using immortalized conjunctival epithelium ( clone 1 - 5c-4 [ wong - kilbourne derivative ( d ) of chang conjunctiva ] , atcc , ccl-20.2)20,21 as the negative control22 and htk - h cells ( human corneal fibroblast cell line)23 as the positive control for hla - dr staining .
to analyze , dot plots for cell size ( forward scatter ) versus cellular granularity ( side scatter ) and fluorescence channel ( fl ) 1 versus cellular granularity ( side scatter ) and a histogram ( fl1 versus event count ) were plotted , demonstrating a single homogenous cell population ( figure 1 ) .
analytic gates were set around the area of interest to exclude cellular debris and aggregates .
the percentage of hla - dr positive cells was obtained from a cytogram , yielding the histogram s statistics , indicating the mean intensity of cell fluorescein that was proportional to hla - dr expression . in each sample ,
samples from each eye were analyzed separately and independently.8,9,1114 all specimens were processed by a masked observer .
clinical assessments included the ocular surface disease index ( osdi ) questionnaire , tear film break - up time ( tfbut ) , corneal and conjunctival staining with fluorescein and lissamine , and schirmer testing with anesthesia.2427 the osdi questionnaire was completed following the standard technique by stevenson et al.27 standardized tfbut was done by instillation of 5 l of 2% fluorescein onto the conjunctival fornices and recording the time for the tear film to break up on the corneal surface .
corneal staining was then assessed using the national eye institute scale for grading , dividing the corneal surface into five areas and scoring accordingly ( grade of 015 per eye).2426 conjunctival staining was evaluated using lissamine - impregnated strips wetted with artificial tears , and conjunctival staining pattern was graded according to density , using a scale of 03 on both the nasal and temporal conjunctiva ( grade of 06 per eye).24,25 impression cytology was then performed using the technique described earlier .
schirmer testing with anesthesia was performed by instilling anesthetic drops onto the lower conjunctival fornices , then waiting for 3 minutes before placing the tear strips on the lower lid margin .
patients were asked to close their eyes for 5 minutes before taking the readings.24 the modified dry eye workshop ( dews ) score was graded based on the aforementioned tests and clinical evaluation mentioned .
the patients were then given a dews classification of ded severity ( table 1 ) , where scores from individual dry eye test were replaced with severity grading score of 14.24 visual acuity , intraocular pressure measurement , and slit lamp biomicroscopy were also done as part of safety parameters .
statistical analysis was performed using spss ( ibm corporation , armonk , ny , usa ) and ncss ( ncss , llc , kayesville , ut , usa ) . within - patient , before and after treatment comparisons were conducted using paired t - tests .
three patients did not return for their day 30 evaluation and were not included in the final analysis .
there were two enrolled patients who had been on restasis for more than 6 months .
after 30 days of treatment with peg / pg + hp - guar , statistically significant changes ( p<0.0001 ) were observed in the mean corneal staining ( 5.383.63 to 2.713.08 points ) , with an improvement of 2.68 points or 51% ; tfbut
( 2.391.64 to 4.192.25 points ) , with an improvement of 1.80 points or 115% ; and the total dews score ( 2.100.90 to 0.820.83 points ) , with an improvement of 1.28 points or 58% .
there were also statistically significant changes in mean osdi score ( 41.5423.62 to 32.9123.16 points ) , with an improvement of 8.63 points or 19% ( p=0.0204 ) .
results from conjunctival staining showed improvements after 30 days of treatment ; however , they were not statistically significant ( table 3 ) .
sixty - three percent of patients had decreased hla - dr expression in one or both the eyes , and 43% had increased expression in one or both the eyes after 30 days of lubricant eyedrop use . the percentage of hla - dr positive cells obtained from the resultant cytogram , indicating the mean intensity of cell fluorescein , which was proportional to hla - dr expression , revealed a change from 7.176.10 to 3.772.12 , showing a significant decrease of about 50% ( p=0.0212 ; table 4 ) .
these numbers reflect a general decrease in the inflammatory marker hla - dr in eyes treated with peg / pg + hp - guar for 4 weeks .
representative plots from one patient ( taken from the right eye ) are shown , demonstrating hla - drpositive cells before and after treatment ( figures 2 and 3 ) .
there were no reports of adverse events for the duration of the study , neither observed by the investigator nor reported by the patient .
our study suggests that regular use of over - the - counter lubricant eyedrops for 1 month may lead to decreased inflammatory response of the ocular surface , as measured by the percentage of hla - dr positive cells obtained through impression cytology .
this study also suggests a mechanism of how a lubricant eyedrop solution may help in providing improvement in ded beyond palliative treatment .
in addition , it demonstrates the usefulness of a biomarker of inflammation , percent - positive hla - dr cells , for assessing treatment in ded and inflammation of the ocular surface and its responsiveness to change with an intervention . the use of minimally invasive objective metrics for evaluating the severity of disease and effectiveness of treatment may provide better endpoints for future clinical trials of ded and other ocular surface abnormalities .
levels of proinflammatory cytokines , chemokines , and inflammatory t cells have been found to be elevated not only in patients suffering from autoimmune ocular diseases such as sjgren s syndrome but also in non - sjgren s dry eye .
stability of the ocular surface depends on a number of factors interplaying to keep and preserve the integrity of the tear film and transparency of the cornea .
these factors include sensory inputs from the ocular surface resulting in reflex tear production as well as proper tear film composition .
if any of these is altered , inflammation will result , causing even more tear film instability , entering into a vicious cycle.17 hla - dr is a glycoprotein transmembrane complex , part of the major histocompatibility complex ii .
these molecules are present in antigen - presenting cells , which activate t cells as part of an inflammatory cascade .
although hla - dr is also expressed in normal conjunctiva , studies have shown that expression is significantly upregulated in patients with ded compared with normal eyes.37 alterations of the conjunctival surface can be analyzed by impression cytology .
this is a minimally invasive method wherein surface epithelial cells can be harvested and analyzed using indirect immunofluorescence and flow cytometry .
it was believed that only immune cells express hla - dr , but using the techniques mentioned earlier in the analysis of dry eye patients , studies have shown the expression of hla - dr by conjunctival epithelial cells is correlated with the severity of the disease.6 this marker appears to reflect disease progression in mild to moderate dry eyes and may even be expressed in those with mild disease with no signs of ocular surface damage.5 it would then theoretically follow that the use of immunomodulatory agents had a role in the treatment of dry eyes , which is the reason why a wide range of drugs ( eg , corticosteroids , doxycycline , cyclosporine a , mycophenolate mofetil , tacrolimus , rapamycin , leflunomide ) have been tested in laboratory or clinical settings for the treatment of ded .
use of some of these drugs has improved signs and symptoms of ded , but some have adverse effects , including pain , discomfort , and secondary ocular changes such as cataracts and glaucoma , all of which may limit their long - term use.28 with the use of the biomarker hla - dr , therapeutic approaches to modulate inflammation associated with dry eye can indirectly be monitored .
snchez et al performed a prospective , randomized study to assess the effect of an artificial tear eyedrop containing hp - guar in ded after cataract surgery.19 this study randomized patients who had undergone cataract surgery into those receiving the usual postoperative eyedrops ( antibiotic + steroid ) and those receiving the same drops plus the artificial tear with hp - guar .
the following clinical assessments were evaluated : osdi , surface staining , tear break - up time , and schirmer scores , as well as laboratory analysis by flow cytometry to evaluate inflammatory markers and compared data from postoperative day 1 and postoperative day 30 .
this study found significant differences in tfbut , osdi scores , and inflammatory markers hla - dr and cd11b .
major histocompatibility complex hla - dr is particularly relevant because it is normally expressed only by antigen - presenting cells but is expressed by ocular surface epithelial cells during immune - driven inflammation . in ded
, immune - driven inflammation occurs when ocular surface epithelial cells express markers such as hla - dr , which elicit further t - cell response , creating a cycle of inflammation and surface damage . because of this
, hla - dr can be used to monitor inflammatory activity on the ocular surface and possibly the effectiveness of dry eye treatment .
although studies have shown some pharmaceuticals increased tear production and decreased inflammation , patients with severe dry eyes find incomplete relief of symptoms and usually still need a supplemental use of an artificial tear product.29 the use of tear substitutes as part of the management of ded is a form of symptomatic approach to the treatment .
tear substitutes or artificial tears sometimes contain additional agents that increase their viscosity in order to improve patients comfort and return the ocular surface and tear film to the normal homeostatic state .
hp - guar is used as a gelling or filming agent added to peg / pg and has been suggested to preferentially bind to more desiccated or damaged areas of the surface of epithelial cells providing protection.3032 when hp - guar ( ph of 7.0 ) comes into contact with tears ( ph 7.57.8 ) , it forms a matrix with borate ions , and thus , the contact time with the peg / pg lubricant is prolonged , which leads to a stabilization of the tear film.32 in rabbits , an exposure as short as 1 week could lead to an increase in precorneal mucous layer thickness.18 a study done by sall et al showed that cyclosporine a ( restasis ) combined with an artificial tear worked well in improving signs and symptoms of ded ; however , not all artificial tears worked the same.33 they found that restasis combined with a lubricant systane ( alcon ) that contained peg / pg and the gelling agent hp - guar worked better than when combined with a preservative - free carboxymethylcellulose agent refresh plus ( allergan ) .
interestingly , restasis combined with systane compared to systane alone did not show any statistically significant difference in the improvement of signs and symptoms.33 according to the dews report on the management and therapy of dry eye in 2007 , although ocular lubricants have been shown to provide some protection of the ocular surface , and some improvement in patient symptoms and objective findings , they have not been demonstrated in controlled clinical trials to be sufficient to resolve ocular surface disorder and inflammation seen in most dry eye sufferers.34 springs searched for peer - reviewed articles related to ded and peg/ pg + hp - guar and concluded that the drops would reduce corneal and conjunctival staining in patients diagnosed with this condition , improve tear film stability , have a low coefficient of friction in an in vitro model , and improve maintenance of best - corrected visual acuity over time.32 however , there was no mention of this preparation being effective in modulating inflammation associated with ded . in our study , it was shown that following 30 continuous days of use with the peg / pg + hp - guar , there were statistically significant improvements in measurements of general ocular health .
as part of the methodology , we also analyzed the effect of treatment on the ocular surface using impression cytology and used flow cytometry to monitor inflammatory markers associated with ded .
we found that the use of peg / pg + hp - guar in our study protocol not only led to reductions of the total dews score but also improvement in osdi score , corneal staining , and tfbut .
more than half of the patients showed decreased expression of hla - dr after treatment with peg / pg + hp - guar .
not all patients showed the same magnitude of decrease in hla - dr and some patients showed an increase in hla - dr despite improvement in clinical signs and symptoms of ded .
this may be due to individual variability in response to the treatment , or possibly , some may require more time to achieve a decrease in surface inflammation .
our masked analysis demonstrated that overall , the average percentage of hla - dr positive cells was significantly decreased on the ocular surface after 30 days of use of peg / pg + hp - guar ( p=0.02 ) . to our knowledge , this is the first reported evidence that an over - the - counter lubricant eyedrop solution can help decrease the immune response of the ocular surface in patients primarily diagnosed with ded , as evidenced by a reduction in a biomarker of ocular inflammation , percent positive hla - dr cells .
similar results have been published by snchez et al , who demonstrated that the use of peg / pg + hp - guar after phacoemulsification decreased dry eye parameters and inflammatory markers including hla - dr ; hence , the use of these drops might not only be an option for primary dry eye patients but also for dry eye or ocular surface diseases associated with ocular procedures.19 this demonstrates that impression cytology and flow cytometry may be considered a minimally invasive and objective means to monitor the disease process as well as treatment effects in ded .
these results underscore the need for further , large - scale studies concerning the use of artificial tears not only as a symptomatic treatment but also objectively as a therapy reducing parameters of disease activity .
the small sample size did not allow for multivariate testing for correlation of hla - dr expression with other inflammatory markers .
further , the study was open - label with only one arm and no control group .
the absence of a control group did not allow a comparison between treatment with the study formulation and no treatment , which somewhat limits the strength of conclusions that can be drawn regarding the effects of the study formulation .
also , two of the patients analyzed had been using an anti - inflammatory agent , cyclosporine a ( restasis ) at the time of enrollment and there was no washout period .
because of the anti - inflammatory nature of restasis , post - treatment decrease in inflammatory activity can not be solely attributed to the test drug . despite these limitations ,
our results demonstrated that hla - dr expression significantly decreased from baseline , and many signs and symptoms of ded were significantly improved in patients with ded who received treatment with peg / pg + hp - guar , suggesting that patients may benefit from use of this artificial tear formulation .
we have shown that peg / pg + hp - guar is effective in improving signs and symptoms of ocular surface disease associated with dry eye . interestingly , it was also shown that the inflammatory aspect of the disorder may be further modulated with the use of this lubricant eyedrop solution .
this demonstrates that symptomatic treatment of ded that attempts to bring back the ocular surface to a homeostatic state can produce a corresponding decrease in the immune response of the eye to surface damage .
furthermore , because inflammation plays a pivotal role in ded , impression cytology and flow cytometry may be valuable tools in its diagnosis and treatment and provide an objective minimally invasive biomarker and metric to classify severity of ocular surface disease and to monitor response to treatment .
this study may serve as a preliminary investigation of the role of artificial tears in regulating inflammatory response in ded .
future studies will include larger patient populations , longer follow - up durations , and comparison of peg / pg + hp - guar with other eyedrop formulations for dry eye .
additionally , characterization of the role of inflammatory markers in ded may contribute to improvements in diagnostic modalities and treatment monitoring of this disease .
Output:
| purposeto determine the changes in dry eye disease ( ded ) severity and the percentage of cells expressing hla - dr on the ocular surface following treatment with lubricant eyedrops containing polyethylene glycol and propylene glycol ( peg / pg ) and the gelling agent hydroxypropyl guar ( hp - guar).patients and methodsnineteen patients with ded used peg / pg + hp - guar eyedrops four times per day for 30 days .
assessments included ded severity ( ocular surface disease index [ osdi ] , corneal staining , conjunctival staining , tear film break - up time [ tfbut ] , and schirmer testing ) and impression cytology of the conjunctiva with masked flow cytometry at baseline and at 30 days.resultsthere was a significant decrease in corneal staining ( p<0.01 ) , osdi ( p=0.02 ) , and tfbut ( p<0.01 ) following treatment with peg / pg + hp - guar .
results from flow cytometry revealed a significant decrease in cells expressing hla - dr ( p=0.02).conclusiontreatment with peg / pg + hp - guar eyedrops showed improvement in dry eye severity and reduction in surface inflammation as indicated by a reduction in hla - dr expression . |
PubmedSumm118629 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: oligonucleotides ( oligos ) have re - emerged as a major pharmaceutical target due to the unprecedented opportunity for controlling protein expression mediated by short rna oligomers ( ca .
20 nucleotides long ) through rna interference ( rnai ) with small interfering rna ( sirna ) or micro - rna ( mirna ) , and these have in turn re - invigorated research in the field of anti - sense oligonucleotides ( aso / as - on).[13 ] excitement rose with the recent demonstration of safe and effective delivery of oligos in humans . this imperative has underlined the need for scalable methods of rna synthesis .
today the overwhelming majority of oligos are prepared using solid - phase oligo synthesis ( spos ) , but this is very challenging to scale up .
we are developing a liquid - phase oligo synthesis ( lpos ) synthetic strategy that will be more amenable to standard batch production techniques than spos , using organic - solvent nanofiltration ( osn ) as the critical scalable technology for separating the growing oligo from all other reagents .
we now report the lpos - osn preparation of a 2-methyl rna phosphorothioate 9-mer , monitoring all reactions by hplc , p nmr spectroscopy and ms .
the defining characteristic of spos is the ease of separation of the growing oligo from excess reagents : the solid synthesis support bed / column is simply washed with solvent to remove any molecular species not covalently attached to it .
spos has been scaled up to 12 kg per batch , and the largest trial of the new generation of rnai therapies required a few kg of oligo .
thus it is expected that 100s of kilograms of oligo might be required annually to treat rare diseases , and possibly tons for major ones .
the leading companies in the field have claimed that spos can be extended to yet larger scales .
however , the specialized equipment is demanding and expensive to use in an industrial setting , and we believe that spos , even with major advances , is incapable of approaching the 100 kg scale per batch , because of the challenge of completely and reproducibly washing large beds of synthesis support.[9a ] therefore a very serious gap is expected to open between oligo supply and demand that will restrict this otherwise promising new mode of therapy . consequently , a new method of oligo production is urgently required .
early on scalability was identified as the achilles heel of spos , and lpos has long been proposed to overcome this problem .
however , the critical question that must be addressed in any lpos strategy is how to separate the growing oligo from excess reagents and byproducts .
so far , amongst the alternative strategies reported for the synthesis of oligos , chromatography has been dismissed as too time - consuming , solvent intensive , and inefficient . whilst
approaches including size - exclusion chromatography and extraction have been proposed to overcome this separation problem , precipitation of polymer - supported oligo has been explored much more widely .
initially dna oligos supported on poly(styrene ) ( the same solid - phase support as had recently been used by merryfield for peptide synthesis ) were assembled by means of khorana s phosphodiester approach.[10 , 15 ] subsequent authors explored poly(vinyl alcohol ) ( pva)[16 , 17 ] and cellulose as supports , but poly(ethylene glycol ) came to dominate this strategy wherein the oligonucleotidyl - peg was usually precipitated with diethyl ether.[17 , 1921 ] recently a discrete , non - polymeric synthesis support was developed in which four oligo chains were grown simultaneously around a pentaerythritol core , and the products were then precipitated from methanol.[22 , 23 ] whilst approaches to oligo synthesis based upon precipitation or crystallisation are in theory scalable , it is questionable whether this would be truly practical .
process development of industrial precipitation is often time - consuming and labour - intensive , with the conditions being unique to each compound.[9b ] during bonora s preparation of 10 mg dna 20-mer , 79 separate precipitations and crystallisations were required .
furthermore , it is inevitable that material will always be lost to incomplete separation : on the peg support it was found that losses , starting around 1 % per cycle , became more significant as the increasing solubility of the growing oligo began to overwhelm the polymer - driven phase separation ; during the preparation of an rna 5-mer on the small pentaerythritol support , the coupling cycle yield only averaged 85 % for a 54 % overall yield , which would be unacceptable for commercial production .
the use of membrane - based technologies for the separation of synthetic biopolymers has been little explored , despite their evident potential to realise scalable liquid - phase approaches to valuable targets . in the first such synthesis ,
bayer and mutter bound peptides to mono - methyl peg-10 000 ( mpeg ) that was purified by ultrafiltration .
this approach was repeated for oligos by the same laboratory , using the now obsolete phosphodiester coupling strategy and either pva or peg-10 000 polymeric supports .
alternation between chain extension in organic solvent and diafiltration in water after each chain extension cycle probably makes this strategy impractical .
we postulated that organic - solvent nanofiltration ( osn ) could fulfil the critical separation role in an lpos strategy conducted entirely in organic solution , figure 1 .
furthermore , since organic - solvent stable nanofiltration ( as opposed to ultrafiltration ) membranes are now available , we proposed that a smaller , discrete synthesis support could be used . during osn ,
solutes are separated by size exclusion and geometric selection as they pass through a membrane possessing nanometer - scale permeation pathways .
solutes that can not pass through the membrane are said to be rejected and remain in the upstream retentate .
we further postulated that lpos - osn would provide an excellent platform for monitoring the ongoing oligo synthesis , by means of sampling using a simple liquid draw - off .
although in principle it is also possible to monitor chain extension progress with spos , we are unaware of any report of such a procedure .
this is most likely due to the difficulty of engineering repeated access to beds of solid support in large diameter , pressurized steel columns ( columns for preparing 12 kg oligo by spos have diameters 50100 cm and pressure ratings of 1520 bar ) .
ready access to samples , although providing the opportunity to optimize reactions and to rescue failed steps , is of marginal value on the small synthetic scales regularly produced today
. however , in the future , during the preparation of tens of kilograms to tons of oligos , it would be economically unacceptable to risk the complete loss of such large batches of very expensive building blocks without critical quality control .
the lpos - osn concept : a ) chain extension reaction ; b ) diafiltration by osn to remove excess reagents ; c ) 5-o deprotection ; d ) diafiltration by osn to remove excess reagents , then repeat cycle to the desired length . building on our earlier experience with membrane - enhanced peptide synthesis ( meps ) in organic solvent ( dmf ) , we initially explored osn separation of mpeg-5000-supported dinucleotides .
however , even ,-bis(dinucleotidyl)-peg-10 000 had too low a rejection for practical lpos - osn . therefore we instead adopted monodisperse tris(octagol ) homostar 1 ( a homostar is a star polymer in which all the arms are identical ) as a branched lpos support , see scheme 1 .
we hypothesised that this would have three advantages : 1 ) branching should inhibit threading of the supported oligo into the membrane permeation pathways , and therefore increase membrane rejection of the construct ; 2 ) with three oligos growing around one hub , the molecular weight will rise by three nucleotides per cycle , rapidly increasing the overall size , and hence the rejection of the tris(oligonucleotidyl ) support with oligo length ; and 3 ) since the tris(oligonucleotidyl ) support is a discrete species , hplc and mass spectral ( ms ) analyses of real - time synthetic quality should be feasible .
we next required an osn membrane compatible with acetonitrile , the solvent in which phosphoramidite couplings are typically conducted .
the membrane should also be compatible with feed mixtures containing typical oligo coupling , oxidation / thioylation , capping and 5-o - unblocking reagents .
furthermore , the membrane must be able to permeate nucleotide monomer debris after oligo chain extension ; these species are the largest molecular weight debris generated during the synthesis cycle . to meet these challenges we developed a new class of osn membrane ( pbi-17dbx ) , prepared from poly(benzimidazole ) and cross - linked with para - dibromoxylene .
pbi-17dbx is very resistant to chemical degradation and gave highly reproducible performance in ch3cn , whilst being open enough to allow species of similar size to nucleotide monomers to permeate .
second- and third - generation therapeutic oligos most commonly contain either 2-deoxy or 2-modified nucleosides ( e.g. ; ch3o- , ch3och2ch2o- , f- ) , as well as more complex locked / bridged ribose analogues.[3032 ] for this reason we elected to focus on nucleic acid analogues for our lpos - osn test sequence , instead of native rna .
adoption of lpos - osn by other groups would be encouraged if this technology was compatible with commercial building blocks and common protective group combinations .
therefore we selected readily available 2-methoxy nucleosides , activated as their 2-cyanoethyl ( cne ) n , n - diisopropylphosphoramidites , carrying 5-o-(4,4-dimethoxytriphenylmethyl ) ( dmtr ) temporary protection and with various amides blocking the exocyclic amino groups of the nucleobases .
we also selected the widely used , first - generation phosphorothioate modification as a target for this pilot project because the debris from thioylation reagents is likely to be a more severe test of lpos - osn purification than common oxidants ( e.g. iodine pyridine water , or tert - butyl hydroperoxide ) .
all previous lpos studies , except for that of lonnberg , have concerned the synthesis of dna oligos , which are easier to prepare than rna .
furthermore , with the exception of bonora s dna 20-mer prepared using numerous precipitations and crystallisations , the largest oligo prepared by lpos to date using iterative synthesis is a dna 10-mer , through h - phosphonate coupling ; a dna phosphorothioate 15-mer has also been reported , but this was constructed using dimer building blocks . as a challenging target for this new lpos - osn technology , we set out to synthesise a 2-methyl rna phosphorothioate 9-mer section of the m23d aso .
to assess the performance of the support and phosphoramidite chemistry in this new environment , we planned to undertake global deprotection at both the 5-mer ( four chain extensions ) and 9-mer ( eight chain extensions ) stages .
building on our earlier experience with membrane - enhanced peptide synthesis ( meps ) in organic solvent ( dmf ) , we initially explored osn separation of mpeg-5000-supported dinucleotides .
however , even ,-bis(dinucleotidyl)-peg-10 000 had too low a rejection for practical lpos - osn .
therefore we instead adopted monodisperse tris(octagol ) homostar 1 ( a homostar is a star polymer in which all the arms are identical ) as a branched lpos support , see scheme 1 .
we hypothesised that this would have three advantages : 1 ) branching should inhibit threading of the supported oligo into the membrane permeation pathways , and therefore increase membrane rejection of the construct ; 2 ) with three oligos growing around one hub , the molecular weight will rise by three nucleotides per cycle , rapidly increasing the overall size , and hence the rejection of the tris(oligonucleotidyl ) support with oligo length ; and 3 ) since the tris(oligonucleotidyl ) support is a discrete species , hplc and mass spectral ( ms ) analyses of real - time synthetic quality should be feasible .
we next required an osn membrane compatible with acetonitrile , the solvent in which phosphoramidite couplings are typically conducted .
the membrane should also be compatible with feed mixtures containing typical oligo coupling , oxidation / thioylation , capping and 5-o - unblocking reagents .
furthermore , the membrane must be able to permeate nucleotide monomer debris after oligo chain extension ; these species are the largest molecular weight debris generated during the synthesis cycle . to meet these challenges we developed a new class of osn membrane ( pbi-17dbx ) , prepared from poly(benzimidazole ) and cross - linked with para - dibromoxylene .
pbi-17dbx is very resistant to chemical degradation and gave highly reproducible performance in ch3cn , whilst being open enough to allow species of similar size to nucleotide monomers to permeate .
second- and third - generation therapeutic oligos most commonly contain either 2-deoxy or 2-modified nucleosides ( e.g. ; ch3o- , ch3och2ch2o- , f- ) , as well as more complex locked / bridged ribose analogues.[3032 ] for this reason we elected to focus on nucleic acid analogues for our lpos - osn test sequence , instead of native rna .
adoption of lpos - osn by other groups would be encouraged if this technology was compatible with commercial building blocks and common protective group combinations .
therefore we selected readily available 2-methoxy nucleosides , activated as their 2-cyanoethyl ( cne ) n , n - diisopropylphosphoramidites , carrying 5-o-(4,4-dimethoxytriphenylmethyl ) ( dmtr ) temporary protection and with various amides blocking the exocyclic amino groups of the nucleobases .
we also selected the widely used , first - generation phosphorothioate modification as a target for this pilot project because the debris from thioylation reagents is likely to be a more severe test of lpos - osn purification than common oxidants ( e.g. iodine pyridine water , or tert - butyl hydroperoxide ) .
all previous lpos studies , except for that of lonnberg , have concerned the synthesis of dna oligos , which are easier to prepare than rna .
furthermore , with the exception of bonora s dna 20-mer prepared using numerous precipitations and crystallisations , the largest oligo prepared by lpos to date using iterative synthesis is a dna 10-mer , through h - phosphonate coupling ; a dna phosphorothioate 15-mer has also been reported , but this was constructed using dimer building blocks . as a challenging target for this new lpos - osn technology , we set out to synthesise a 2-methyl rna phosphorothioate 9-mer section of the m23d aso . to assess the performance of the support and phosphoramidite chemistry in this new environment
, we planned to undertake global deprotection at both the 5-mer ( four chain extensions ) and 9-mer ( eight chain extensions ) stages .
homostar 1 was first condensed with 4.5 equivalents 5-dmtr-2-methyl-3-succinyl uridine ( 2 , dmtr - mu - suc - oh ) , see scheme 1 .
classical activation with 8 equivalents n , n-diisopropyl carbodiimide , in addition to catalytic 4-(dimethylamino)pyridine ( dmap , 0.2 equiv ) in thf , was incomplete with excess uridine succinate being consumed as the acyl urea . to maximize the analytical potential of lpos - osn
it is highly desirable to drive loading of the synthesis support to completion to give a homogeneous product , as well as to avoid waste of expensive excess nucleoside on a large scale .
thus , condensation of 4.5 equivalents uridine succinate ( 2 ) with homostar 1 was initiated with more reactive 2,6-dichlorobenzoyl chloride ( dcbcl ) and n - methyl imidazole ( nmi ) , after which no peg - terminal hydroxyls remained .
the resultant tris - dmtr - ether ( 3 ) was then detritylated with dichloroacetic acid ( dca ) , using pyrrole as a cation scavenger , to provide fully loaded homostar 4 in 80 % yield over the two steps , ready to commence the chain extension cycle . at this stage a small amount of dcb - ester ( 5 ) was separated chromatographically from 4 ; although this contaminant would not affect oligo synthesis at all , in this study it was removed to simplify hplc analysis of chain extension . the loaded synthesis support 4 ( 1.24 g ) was next chain extended with 5-dmtr-2-methyl n - acetylcytidine ( dmtr - mc ) phosphoramidite 6 ( 1.5 equiv per oh ) to mumc homostar 7 under typical conditions , see scheme 1 : ethylthiotetrazole ( ett , 3 equiv per oh ) in ch3cn , 35 min , then phenylacetyl disulfide ( pads ) in pyridine , 30 min , monitoring by hplc ( see scheme 1 and supporting information ) .
for this pilot study unusually long times were used for both coupling and thioylation so that the reactions could be sampled and monitored in real time before moving on to the next process . for this reason ,
the widely used ett ( pka 4.3 , 0.25 m in ch3cn ) was selected as the activator , firstly because it is a compromise that provides higher activity than classical tetrazole ( pka 4.8 ) , but less than 4-nitrophenyl tetrazole ( npt , pka 3.7 ) .
secondly , in larger scale couplings with 2-methyl phosphoramidites , 0.5 m ett has proved effective over 515 min reaction times , so 0.25 m ett is commensurate with our longer reactions .
furthermore , although npt has been reported to give very high coupling yields with 2-methyl phosphoramidites , we were concerned that the greater acidity of this activator than ett would exacerbate contamination from double coupling during the long reaction times used here . during spos mass transfer
for fast reactions , such as phosphoramidite coupling , mass transfer is the rate - limiting step.[9a , 24 ] thus , if the same chemistry is used in both cases , yields in lpos are expected to be higher than in spos .
consequently , in an lpos strategy capping should not be as critical as in spos , and this step was omitted simplifying the process during pilot study development .
indeed , it is hoped that assay of the chain extension reaction will in future permit identification of otherwise economically catastrophic failed couplings on very large scales , and provide the opportunity to repeat the reaction . however ,
if capping were implemented before the assay , it would then be impossible to recover a failed coupling .
once chain extension and thioylation were complete , the crude mixture was then diluted with ch3cn , and poured directly into the osn apparatus ( see supporting information ) .
the rig was pressurized with nitrogen to force solvent and solutes through the pbi-17dbx membrane , a process termed diafiltration .
thus , the efficiency of osn can be related to how many retentate system volumes , or
diavolumes , must be permeated to achieve a given degree of purification of the retentate .
after 12 diavolumes , all small molecules had been removed from the retentate . however , along with the desired dmtr - dinucleotidyl homostar ( 7 ) , most of the building block related species , consisting of a mixture of amidates ( 8) and thioate salts ( 9 ) , were retained ( corresponding to n - op in figure 1 ) .
notably , the proportion of phosphoryl species 8 b and 9 b compared to thioyl derivatives 8 a and 9 a ( p = o vs. p = s ) , determined by p nmr spectroscopy of the mixture ( see figure 2 a ) , increased substantially when the amount of pads was reduced from 10 to 3 equivalents per 5-oh .
indeed , thioamidate 8 a was almost undetectable when the intermediate phosphite was thioylated with 3 equivalents pads , although amidate 8 b rose to between 15 and 25 % of the p nmr signal integral intensity of product 7 .
osn of dinucleotidyl homostar monitored by p nmr spectroscopy : a ) tris(mumc - dmtr ) homostar 7 after permeating 12 diavolumes of ch3cn apart from the homostar , amidates 8 a and 8 b , and thioate salts 9 a and 9 b are present ; b ) tris(mumc - oh ) homostar 10 after permeating 5 diavolumes 1 % dca - ch3cn and 10 diavolumes ch3cn ; c ) expansion of b ) exhibiting the two diastereoisomers of the internucleotide linkage , plus a low level of possible n - deacetylation of cytosine ( see supporting information ) .
the crude tris(mumc - dmtr ) homostar 7 was washed from the osn rig and re - dissolved in ch2cl2 .
to this were added pyrrole then dca , and after 30 min the detritylation was complete by hplc .
unlike in spos , in which the detritylation equilibrium is driven to completion by flushing the dmtr cation away from 5-oh oligo bound to the solid support , in solution phase a scavenger ( here pyrrole ) is necessary to ensure total unblocking .
otherwise even small amounts of mono - tritylated homostar would be carried through to the next cycle where ( even after capping ) subsequent detritylation would lead to n1 short - mers .
it had been anticipated that at this stage the smaller fragments from the excess building block ( dmtr - pyrrole , and 5-oh amidates 11 and thioates 12 , now corresponding to p and n - oh in figure 1 ) would then permeate , but they did not . suspecting that ion exchange could occur between the protonatable pbi membrane surface and thioate salts 12 , 1 vol % dca was added to the first five diavolumes .
after a total of 15 diavolumes had permeated the product tris(mumc - oh ) homostar 10 was then of a similar purity to that achieved by flash chromatography .
however , the detritylated amidates ( 11 ) were slower to permeate than the thioate salts 12 , and thioamidate 11 a exhibited substantially greater rejection than amidate 11 b. thus by reducing the excess of pads from 10 to 3 equivalents , when very little or no thioamidate 11 a formed , the purity of dinucleotidyl homostar 10 was maximised ( figure 2 b ) .
dmtr - pyrrole was the only contaminant significantly rejected by pbi 17dbx ( see hplc in supporting information ) .
thus , although dmtr - pyrrole probably does not interfere with subsequent couplings , this was removed by precipitation of tris(mumc - oh ) homostar 10 in diethyl ether so that an accurate mass recovery could be determined ; apart from dmtr - pyrrole no other species could be detected in the supernatant by h or p nmr spectroscopy . after the first chain extension cycle a moderate 75 % yield of tris(mumc - oh ) homostar 10 was isolated .
the only detectable impurity was a low level of cytosine n - deacetylation , identified by lc - ms ( see supporting information ) and believed to be the minor peaks in figure 2 c. despite the need to remove dmtr - pyrrole by precipitation , the above cycle was repeated on homostar 10 , see scheme 2 ; from this point on , all chain extension cycles start with 1.21.4 g tris(5-ho - oligo ) homostar .
thus , after chain extension , dmtr-3-mer homostar 13 was partially purified by osn ( 12 diavolumes ) then detritylated , after which all the nucleotidyl debris was separated by osn , and precipitation was again used to remove residual dmtr - pyrrole . this time during the second diafiltration , the first five diavolumes contained only 0.1 % dca to minimize n - deacetylation .
the 85 % yield of tris(mumcmc - oh ) homostar 14 was significantly higher than that of dinucleotidyl homostar 10 at the same stage ( see scheme 2 , inset graph ) , indicating that as expected the homostar rejection had risen with oligo length .
it should be noted that chain extension cycle yields are calculated assuming 100 % purity of the product homostar .
however , as low levels of side - reactions accumulate on the growing oligo , the purity can not be 100 % , so the molecular weight can not be precisely defined , and the yields are more correctly referred to as apparent yields .
inset : change in apparent yield of isolated 5-oh tris(oligonucleotidyl ) homostar with oligo length . both the tritylated ( 13 ) and detritylated ( 14 ) tris(trinucleotidyl ) homostars were less soluble in ch3cn than the shorter species 4 , 7 and 10a trend that continued with increasing length .
noting that all the oligonucleotidyl homostars ( 1418 and 2027 ) were highly soluble in dmf , all subsequent phosphoramidite couplings were conducted in ch3cn dmf ( ca .
9:1 ) ; this solubility of a branched 2-me - rna 24-mer oligonucleotidyl homostar ( 18 ) may be favorably contrasted with the previously reported poor solubility of 5-oh dna 8-mers in ch3cn .
the solvent was also changed during osn from neat ch3cn , in which tris(tetranucleotidyl ) homostar 16 is almost insoluble , to ch3oh ch3cn ( 1:4 or 1:3 v / v ) in which all the oligonucleotidyl homostars are soluble up to at least tris(9-mer ) homostar 27 ( 0.4 wt % 27 during final diafiltration ; the saturation conc .
finally , the dca in the second diafiltration was replaced by 1 % pyridinium dichloroacetate ( pydca ) which promoted permeation of thioate salts 12 just as effectively as un - buffered dca .
this protocol was used on 4-mer 16 and for all later chain extension cycles , following each reaction by hplc , and assaying the products by p nmr spectroscopy and maldi ms , both before and after detritylation ( see supporting information ) .
two further rounds of chain extension were conducted , with the apparent yield continuing to rise ( 82 % 16 , 94 % 18 , see inset graph , scheme 2 ) .
although hplc usefully exhibited retention times lengthening in relation to the number of 5-dmtr ethers per homostar , both during chain extension and detritylation , by 5-mers 17 and 18 the peaks were too broad to be of further analytical use ( see supporting information ) , presumably due to the exponentially growing number of diastereoisomers at the p - centers of the oligo backbone .
however , p nmr spectroscopy continued to demonstrate acceptably low levels of amidate contamination after each cycle .
furthermore , ms confirmed that full - length tris(mumcmcmamu - oh ) homostar 18 was the principal product .
by contrast , ms of an oligo conjugated to a polydisperse support would be spread over too many polymeric homologues to provide sufficiently intense peaks for analysis .
pentanucleotidyl homostar 18 was deprotected first with diethylamine , then overnight in aqueous ammonia at 55 c .
the following day , trituration with ch3cn removed protective group debris to give crude 2-methyl rna phosphorothioate 5-mer 19 .
hplc assay of this material ( figure 3 a ) exhibited a moderate purity of 74 % , with both short - mer and long - mer contaminants .
although these short - mers could be explained by lack of capping , we believe that they actually derive from chain extension of residual amidate building block 11 after osn . examination of the mass spectra of the 5-oh tris(oligonucleotidyl ) homostars 10 , 14 , 16 and 18 ( from 2-mer to 5-mer ) exhibit no detectable ions corresponding to incomplete chain extension . since our synthesis support possesses three arms , if 1 % incomplete chain extension had occurred , this would afford approximately 3 % homostar having one arm bearing the n1 short - mer . thus , assuming that maldi ionization of full - length oligohomostars and their singly truncated oligohomostar contaminants are similar , mass spectral analysis of homostars supported oligonucleotides should usefully amplify sequence errors to detectable amounts .
the long - mers probably arise from two sources : 1 ) relatively long coupling times compared to spos ( 35 min vs. 612 min ) were used here to allow time for hplc confirmation of complete coupling .
2 ) n - deacetylation of cytosine residues ( as observed at the dimer stage ) could provide sites for branching , although we suspect that the switching from dca to pydca in the second diafiltration of each cycle largely suppressed this .
hplc of deprotected oligos : a ) crude 5-mer 19 , 75 % purity ; b ) crude 9-mer 28 , 49 % , containing 8-mer 29 , 18 % ; c ) purified 9-mer 28 , 94 % , from lpos - osn ; d ) 9-mer 28 , 95 % , from spos .
chain extension was continued from tris(pentanucleotidyl ) homostar 18 with the same protocol for another four cycles , and p nmr spectroscopy and ms now served as the principal methods of product characterization , to obtain 1.36 g of the desired tris(nonanucleotidyl ) homostar 27 .
apparent yields of detritylated 6- to 9-mer homostars 21 , 23 , 25 and 27 now plateaued around an average of 95 % ( see inset graph , scheme 2 ) .
finally , at the 9-mer stage ms indicated incomplete coupling with approximately 90 % conversion per chain ( 2526 ) .
this material was detritylated and deprotected as before to characterize the crude 9-mer by hplc ( figure 3 b ) ;
as implied by the homostar ms , hplc indicated 49 % of the desired 9-mer 28 , plus 17 % of the expected 8-mer impurity 29 ( confirmed by lc - ms , see supporting information ) .
the 9-mer was then fractionated for confirmatory analysis through two ion - exchange columns to 94 % purity ( figure 3 c ) , and desalted providing a 16 % ( 29 mg ) yield of pure 9-mer 28 from 5-oh homostar 27 .
this material displayed identical hplc ( figure 3 d ) and ms to 9-mer 28 prepared by spos .
in this report we have demonstrated for the first time a new liquid - phase synthesis and separation paradigm for oligonucleotides : liquid - phase oligonucleotide synthesis / organic - solvent nanofiltration , lpos - osn .
this promising technology has yet to equal the speed and purity of spos , requiring around two days per chain extension cycle with the limited area available from current laboratory - scale flat membrane cells .
however , the fact that we were able to perform eight chain extension and detritylation cycles , with intermediate purifications , all in the liquid phase demonstrates that it has high potential .
compared to competing precipitation strategies , lpos - osn is more amenable to industrial exploitation because liquid - phase handling is intrinsically scalable .
lpos - osn also has the major advantage over spos that it is straightforward to sample and monitor every step of the process .
apart from p nmr spectroscopy and hplc , the choice of a monodisperse support also allowed characterization of the growing oligonucleotidyl homostars by ms . from the above experience
, several modifications can be suggested to improve future protocols : shortening the coupling time , and analysing only after thioylation , will reduce long - mer formation . minimising 5-unblocking time , and therefore acid exposure , will minimise cytosine deacetylation , and again possible long - mer formation .
biasing building block debris away from amidates ( 8/11 ) into thioates ( 9/12 ) that are more easily removed by diafiltration would suppress short - mer formation .
the overall yield of fully protected 5-oh tris(oligonucleotidyl ) homostar 27 from loaded uridine homostar 4 is only about 39 % , mainly due to poor recovery from the early cycles of osn ; the first three couplings ( 44-mer 14 ) give a cumulative yield of only 52 % , but the next five couplings ( 4-mer 189-mer 27 ) have a combined yield of about 76 % .
this will be much improved using our recently developed 2-stage diafiltration ; we would expect early stage recovery to be > 95 % and from 5-mer onwards > 99 % . as with spos ,
we have recently demonstrated that an additional stage of diafiltration with a low - molecular - weight cut - off membrane can be used to recycle the permeate solvent , greatly reducing the potential cost on an industrial scale . as the scale of lpos - osn increases , an alternative analysis to direct hplc of the retentate will be required ; we believe that rapid ammonia - methylamine ( ama ) global deprotection , followed by hplc of the crude unblocked oligo will provide a suitable method to assay for complete chain extension .
finally , identifying a membrane that permeates dmtr derivatives , or using a smaller 5-protecting group , such as the methoxyisopropylidene acetal , would make the process even more efficient .
chemical shifts in ppm are referenced with respect to residual solvent signals : h ( chcl3 ) 7.25 ppm , h ( chd2od ) 3.31 ppm , h ( cd3cochd2 ) 2.05 ppm ; c ( cdcl3 ) 77.50 ppm , c ( cd3od ) 49.15 ppm , c ( cd3cochd2 ) 29.92 ppm .
the splitting patterns for h nmr spectra are denoted as follows ; s ( singlet ) , d ( doublet ) , t ( triplet ) , q ( quartet ) , quin ( quintet ) , m ( multiplet ) , br ( broad ) and combinations thereof .
c nmr assignments ( c , ch , ch2 and ch3 ) and h nmr assignments were established with the aid of dept-135 , hsqc and cosy experiments .
molecular fragments not abbreviated in main text are denoted as follows : u , uracil ; c , cytosine ; ri , ribose ; suc , succinate ; hub , c6h3(ch2or)3 .
nmr spectrscopy of small dmtr derivatives was conducted in the presence of either a small amount of et3n or of pyridine .
mass spectra were recorded on micromass maldi micro mx , or micromass lct premier ( esi ) mass spectrometers .
other reagents were purchased from sigma - aldrich ltd . and used as supplied , except where specified .
dichloromethane , acetonitrile , thf and dmf were dried and stored over baked 4 molecular sieves .
triethylamine , diethyl ether , methanol , isopropanol and n - methyl imidazole were used as supplied .
flash chromatography was conducted in a 9 cm diameter , porosity 3 glass sinter funnel : geduran ( si 60 ) from merck was used for normal phase columns , and merck silanised silica for reverse phase columns .
thin - layer chromatography was carried out using merck silica gel 60 f254 aluminium - backed plates ; compounds were visualised using uv light or kmno4 stain .
solid phase oligonucleotide synthesis ( spos ) was carried out on a ge akta oligopilot 10 , using preloaded 2ome u primer support 200 and manufacturer s standard protocols on a 30 mol scale .
cleavage from solid support and deprotection of nucleobases was carried out in 0.88 aqueous ammonia at 55 c for 16 h. tris-1,3,5-{-[2-o - methyl-5-o-(4,4-dimethoxytriphenylmethyl)uridine-3-o - succinyloxy]octa(ethylene glycol)--oxymethyl}benzene ( 3 ) : compound 1 ( 1.125 g , 1.00 mmol ) was co - evaporated from ch3cn ( 315 ml ) , re - dissolved in ch2cl2 ( 7 ml ) and a dropping funnel was fitted to the flask .
2-o - methyl-3-o - succinyl-5-o-(4,4-dimethoxytriphenylmethyl)uridine , triethylammonium salt ( 2 , 3.047 g , 4.00 mmol ) was co - evaporated from thf ( 350 ml ) , then re - dissolved in ch2cl2 ( 14 ml ) and n - methylimidazole ( 0.63 ml , 7.9 mmol ) then 2,6-dichlorobenzoyl chloride ( dcbcl , 0.54 ml , 3.77 mmol ) were added . after stirring for 20 min ,
the activated succinate solution was transferred to the dropping funnel , rinsing out the flask with further ch2cl2 ( 5 ml ) , and this solution slowly added to homostar 1 over 45 min . after stirring over night
the aqueous layer was back - extracted with small portions of ch2cl2 ( 50 ml3 ) , the combined organic layers dried over na2so4 , and the solvent stripped off in vacuo .
the residual foam may be purified chromatographically by fractionation through a column of silanised silica , eluting with a gradient of ch3cn water ( 3:7 to 8:2 v / v containing 0.5 % sat .
chcl3 1:9 + trace et3n ) 0.56 ; h nmr ( 400 mhz , cdcl3 ) : =7.88 ( d , j=8.2 hz , 3 h ; u ch ) , 7.387.36 ( m , 6 h ; dmtr ch ) , 7.32 ( t , j=7.5 hz , 6 h ; dmtr ch ) , 7.297.24 ( m , 18 h ; hub ch + dmtr ch ) , 6.86 ( d , j=8.9 hz , 12 h ; dmtr ch ) , 6.04 ( d , j=3.7 hz , 3 h ; 1-ch ) , 5.33 ( d , j=8.2 hz , 3 h ; u ch ) , 5.29 ( t , j=5.6 hz , 3 h ; 3-ch ) , 4.55 ( s , 6 h ; hub - ch2o ) , 4.264.24 ( m , 9 h ; 4-ch + suc - och2 ) , 4.10 ( dd , j=5.1 , 3.7 hz , 3 h ; 2-ch ) , 3.81 ( s , 18 h ; och3 ) , 3.713.58 ( m , 93 h ; ch2o + 5-chh ) , 3.483.44 ( m , 12 h ; 2-och3 + 5-chh ) , 2.732.66 ppm ( m , 12 h ; suc ch2 ) ; c nmr ( 101 mhz , cdcl3 ) : =171.98 ( 3 c ; suc c = o ) , 171.53 ( 3 c ; suc c = o ) , 163.29 ( 3 c ; u c ) , 158.73 ( 6 c ; dmtr
c ) , 150.30 ( 3 c ; u c ) , 144.13 ( 3 c ; dmtr
c ) , 139.78 ( 3 c ; u 6-ch ) , 138.57 ( 3 c ; hub c ) , 134.98 ( 3 c ; dmtr c ) , 134.86 ( 3 c ; dmtr
c ) , 130.17 ( 6 c ; dmtr ch ) , 130.09 ( 6 c ; dmtr ch ) , 128.08 ( 12 c ; dmtr ch ) , 127.24 ( 3 c ; dmtr ch ) , 126.32 ( 3 c ; hub ch ) , 113.33 ( 12 c ; dmtr ch ) , 102.51 ( 3 c ; u 5-ch ) , 87.39 ( 3 c ; dmtr
c ) , 87.13 ( 3 c ; 1-ch ) , 82.18 ( 3 c ; ri ch ) , 81.03 ( 3 c ; ri ch ) , 73.06 ( 3 c ; hub - ch2o ) , 70.54 ( 39 c ; ch2o ) , 70.36 ( 3 c ; ri
ch ) , 69.51 ( 3 c ; ch2o ) , 69.02 ( 3 c ; ch2o ) , 63.94 ( 3 c ; ch2o ) , 61.56 ( 3 c ; 5-ch2 ) , 59.03 ( 3 c ; 2-och3 ) , 55.26 ( 6 c ; dmtr och3 ) , 28.88 ( 3 c ; suc ch2 ) , 28.83 ppm ( 3 c ; suc ch2 ) ; ms ( maldi - tof+ ) : m / z calcd for [ c162h210n6nao57 ] : 3175.4 ; found : 3176 [ 3+na ]
. tris-1,3,5-[-(2-o - methyluridine-3-o - succinyloxy)octa(ethylene glycol)--oxymethyl]benzene ( 4 ) : the crude tris(dmtr - mu ) homostar 3 ( 4.438 g from the above procedure ) was dissolved in ch2cl2 ( 40 ml ) and pyrrole ( 1.39 ml , 19.6 mmol ) was added .
dichloroacetic acid was then added in aliquots ( 0.40 ml , 4.8 mmol ) until a strong orange colour remained , and then dissipated over 20 min ; four aliquots were required to overwhelm buffering of the crude dmtr ether and tlc confirmed complete unblocking of intermediate 3 .
the aqueous layer was back - extracted with ch2cl2 ( 50 ml4 ) , organic layers combined , dried over na2so4 and the solvent stripped off under reduced pressure .
the residue was fractionated through a column of silica gel ( 180 ml ) in a large sinter funnel , eluting with a gradient of ch3oh
bands containing dcb - ester 5 ( 409 mg ) , mixed with some product , and compound 4 ( 1.644 g , 80 % ) were isolated as colourless gums .
rf ( ch3oh chcl3 1:9 ) 4 0.35 ; 5 0.51 ; h nmr ( 400 mhz , cdcl3 ) : =9.53 ( br d , j=2.3 , 3 h ; u 4-nh ) , 7.85 ( d , j=8.1 hz , 3 h ; u 6-ch ) , 7.23 ( s , 3 h ; hub ch ) , 5.85 ( d , j=5.1 hz , 3 h ; 1-ch ) , 5.76 ( dd , j=8.0 , 2.0 hz , 3 h ; u 5-ch ) , 5.32 ( t , j=4.6 hz , 3 h ; 3-ch ) 4.55 ( s , 6 h ; hub - ch2o ) , 4.26 ( dt , j=5.4 , 2.0 hz , 6 h ; suc - och2 ) , 4.224.19 ( m , 6 h ; 4-ch + 2-ch ) , 3.94 ( br d , j=12.0 hz , 3 h ; 5-chh ) , 3.79 ( br dd , j=12.3 , 4.0 hz , 3 h ; 5-chh ) , 3.723.61 ( m , 90 h ; ch2o ) , 3.43 ( s , 9 h ; 2-och3 ) , 2.762.68 ppm ( m , 12 h ; suc ch2ch2 ) ; c nmr ( 101 mhz , cdcl3 ) : =172.08 ( 3 c ; suc c = o ) , 171.68 ( 3 c ; suc c = o ) , 163.92 ( 3 c ; u c ) , 150.75 ( 3 c ; u c ) , 141.22 ( 3 c ; u 6-ch ) , 138.51 ( 3 c ; hub c ) , 126.29 ( 3 c ; hub ch ) , 102.64 ( 3 c ; u 5-ch ) , 88.69 ( 3 c ; 1-ch ) , 83.18 ( 3 c ; 2/4-ch ) , 81.43 ( 3 c ; 2/4-ch ) , 73.00 ( 3 c ; hub - ch2o ) , 70.96 ( 3 c ; 3-ch ) , 70.48 ( 39 c ; ch2o ) , 69.46 ( 3 c ; ch2o ) , 68.96 ( 3 c ; ch2o ) , 63.90 ( 3 c ; suco - ch2 ) , 61.15 ( 3 c ; 5-ch2 ) , 58.90 ( 3 c ; 2-och3 ) , 28.95 ppm ( 6 c ; suc ch2ch2 ) ; ms ( maldi - tof+ ) : m / z calcd for [ c99h156n6nao51 ] : 2268.97 ; found : 2269.0 [ 4+na ] .
tris-1,3,5-{-(2-o - me-5-o-{[2-o - me-5-o-(dmtr)-4-n - acetylcytosin-3-yl](2-cyanoethyloxy)thiophosphoryl}uridinyl-3-o - succinyloxy)octa(ethylene glycol)--oxymethyl}benzene , tris(mupsmc - odmtr ) homostar ( 7 ) : tris(2-methyluridine ) homostar 4 ( 422 mg , 0.188 mmol ) and compound 6 ( 678 mg , 0.846 mmol , 4.5 equiv ) were co - evaporated from ch3cn ( 310 ml ) in vacuo .
to the residue was added 0.25 m ett in ch3cn ( 6.77 ml , 1.69 mmol , 9 equiv ) , and after 40 min , pads ( 1.71 g , 5.65 mmol , 30 equiv ) and pyridine ( 6.8 ml ) were added .
after a further 60 min the solvent was stripped off under reduced pressure and the residue fractionated through a column of silanised silica , eluting with a gradient of water
the resultant emulsion was extracted with ch2cl2 ( 100 ml4 ) , the organic layer dried over na2so4 , and then evaporated to dryness .
the appropriate fractions were extracted as before to afford compound 7 ( 538 mg , 64 % ) .
rf ( ch3oh ch2cl2 1:9 ) 0.41 ; intermediate tris(phosphite triester ) 0.54 ; h nmr ( 400 mhz , d6-acetone ) : =10.38 ( br s , 1.5 h ; nh ) , 10.25 ( s , 1.5 h ; nh ) , 10.19 ( s , 1.5 h ; nh ) , 10.15 ( br s , 1.5 h ; nh ) , 8.49 ( d , j=7.4 hz , 3 h ; c ch ) , 7.75 ( d , j=8.2 hz , 1.5 h ; u
ch ) , 7.64 ( d , j=8.2 hz , 1.5 h ; u ch ) , 7.547.51 ( m , 6 h ; dmtr ch ) , 7.427.36 ( m , 18 h ; dmtr ch ) , 7.337.30 ( m , 3 h ; dmtr ch ) , 7.28 ( s , 3 h ; hub ch ) , 7.13 ( d , j=7.2 hz , 1.5 h ; c ch ) , 7.12 ( d , j=7.4 hz , 1.5 h ; c ch ) , 6.976.93 ( m , 12 h ; dmtr ch ) , 6.076.04 ( m , 3 h ; 1-ch ) , 5.995.96 ( m , 3 h ; 1-ch ) , 5.71 ( d , j=7.7 hz , 1.5 h ; u ch ) , 5.70 ( d , j=7.8 hz , 1.5 h ; u
ch ) , 5.375.26 ( m , 2 h ; 23-ch ) , 4.56 ( s , 6 h ; hub - ch2o ) , 4.534.37 ( m , 9 h ; u 4-ch + c 4-ch + pochhch2cn ) , 4.364.15 ( m , 21 h ; u 2-ch + c
2-ch + 5-ch2 + pochhch2cn + suc - och2 ) , 3.84 ( s , 9 h ; dmtr och3 ) , 3.83 ( s , 9 h ; dmtr och3 ) , 3.693.53 ( m , 105 h ; ch2o + 5-ch2 + 2-och3 ) , 3.41 ( s , 4.5 h ; 2-och3 ) , 3.40 ( s , 4.5 h ; 2-och3 ) , 3.01 ( t , j=7.2 hz , 3 h ; ch2cn ) , 2.92.87 ( m , 3 h ; ch2cn ) ,
2.762.73 ( m , 6 h ; suc ch2 ) , 2.702.67 ( m , 6 h ; suc ch2 ) , 2.25 ( s , 4.5 h ; ac ch3 ) , 2.24 ppm ( s , 4.5 h ; ac ch3 ) ; c nmr ( 101 mhz , d6-acetone ) : =171.89 ( 3 c ; c = o ) , 171.45 ( 3 c ; c = o ) , 170.66 ( 3 c ; c = o ) , 163.09 ( 3 c ; u / c c ) , 162.68 ( 1.5 c ; u / c c ) , 162.64 ( 1.5 c ; u / c c ) , 158.92 ( 6 c ; dmtr
c ) , 154.71 ( 1.5 c ; c c ) , 154.60 ( 1.5 c ; c
c ) , 150.47 ( 1.5 c ; u c ) , 150.44 ( 1.5 c ; u c ) , 144.44 ( 1.5 c ; c ch ) , 144.30 ( 1.5 c ; c ch ) , 144.27 ( 1.5 c ; dmtr
c ) , 140.02 ( 3 c ; u 6-ch ) , 139.00 ( 3 c ; hub c ) , 135.43 ( 1.5 c ; dmtr c ) , 135.33 ( 1.5 c ; dmtr
c ) , 130.27 ( 6 c ; dmtr ch ) , 130.18 ( 6 c ; dmtr ch ) , 128.48 ( 3 c ; dmtr ch ) , 128.40 ( 3 c ; dmtr ch ) , 128.02 ( 6 c ; dmtr ch ) , 127.18 ( 3 c ; dmtr ch ) , 125.70 ( 3 c ; hub ch ) , 117.59 ( 1.5 c ; cn ) , 117.31 ( 1.5 c ; cn ) , 113.27 ( 12 c ; dmtr ch ) , 102.65 ( 1.5 c ; u 5-ch ) , 102.52 ( 1.5 c ; u 5-ch ) , 96.15 ( 3 c ; c ch ) , 88.80 ( 1.5 c ; 1-ch ) , 88.51 ( 1.5 c ; 1-ch ) , 88.04 ( 1.5 c ; 1-ch ) , 87.99 ( 1.5 c ; 1-ch ) , 87.08 ( 1.5 c ; dmtr c ) , 87.06 ( 1.5 c ; dmtr
c ) , 82.09 ( 1.5 c ; ri ch ) , 81.78 ( 1.5 c ; ri ch ) , 80.91 ( 3 c ; ri ch ) , 80.79 ( 3 c ; ri ch ) , 80.1580.00 ( m , 3 c ; ri ch ) , 73.51 ( 1.5 c ; ri ch ) , 73.28 ( 1.5 c ; ri ch ) , 72.54 ( 3 c ; hub - ch2o ) , 70.58 ( 3 c ; ri ch ) , 70.35 ( 39 c ; ch2 ) , 69.64 ( 3 c ; ch2o ) , 68.72 ( 3 c ; ch2o ) , 67.4267.10 ( 3 c ; u 5-ch2 ) , 63.7563.48 ( m , 6 c ; ch2o + poch2ch2cn ) , 60.57 ( 1.5 c ; c
5-ch2 ) , 60.49 ( 1.5 c ; c 5-ch2 ) , 58.40 ( 1.5 c ; 2-och3 ) , 58.33 ( 1.5 c ; 2-och3 ) , 58.13 ( 1.5 c ; 2-och3 ) , 57.83 ( 1.5 c ; 2-och3 ) , 54.81 ( 3 c ; dmtr och3 ) , 54.79 ( 3 c ; dmtr och3 ) , 28.67 ( 6 c ; suc ch2 ) , 24.13 ( 1.5 c ; ac ch3 ) , 24.05 ( 1.5 c ; ac ch3 ) , 19.0718.90 ppm ( m , 3 c ; ch2cn ) ; p nmr ( 162 mhz , d6-acetone ) =67.33 ( 0.39 p ) , 67.11 ppm ( 0.61 p ) ; ms ( maldi - tof+ ) : m / z calcd for [ c207h269n18nao79p3s3 ] : 4484.59 ; found : 4484.1 [ 7+na+h2o ]
. tris(mupsmc - oh ) homostar ( 10 ) : tris(dmtro-2-mer ) homostar 7 ( 192 mg , 43 mol ) was placed in ch2cl2 ( 1 ml ) , to which pyrrole ( 35 l ) then dca ( 35 l ) were added .
after 60 min the reaction was complete by tlc and 1 m triethylammonium bicarbonate ( teab , 0.5 ml ) was added , followed by sufficient ch3cn to give a clear solution .
the solution was concentrated at reduced pressure until all ch2cl2 had evaporated , then silanised silica ( 10 ml ) was added to the remaining solution followed by the slow addition of water ( 90 ml ) with gentle swirling , plus 1 m teab ( 1 ml ) .
the silica was collected in a glass sinter funnel , and the pad was washed with water ( 50 ml ) , then ch3cn water ( 1:3 v / v , 160 ml plus 1.5 ml teab ) and the filtrate was discarded . next the silica was washed with ch3cn ( 150 ml ) and the filtrate evaporated to dryness .
the residue ( 156 mg ) was taken up in chcl3 ( 20 ml ) and to the swirled solution was added normal phase silica ( 10 ml ) .
the silica was collected in a glass sinter funnel , the pad was washed with further chcl3 ( 130 ml ) and the filtrate discarded . finally the silica was washed with ch3oh chcl3 ( 1:9 v / v , 150 ml ) and the filtrate evaporated to dryness to afford compound 10 ( 118 mg , 77 % ) .
chcl3 1:9 ) 0.19 ; h nmr ( 500 mhz , cdcl3cd3od 2:1 v / v ) : =8.42 ( d , j=7.5 hz , 1.5 h ; c ch ) , 8.41 ( d , j=7.6 hz , 1.5 h ; c ch ) , 7.63 ( d , j=8.1 hz , 1.5 h ; u
ch ) , 7.402 ( d , j=7.5 hz , 1.5 h ; c ch ) , 7.397 ( d , j=7.6 hz , 1.5 h ; c ch ) , 7.21 ( s , 3 h ; hub ch ) , 5.98 ( d , j=3.7 hz , 3 h ; ri 1-ch ) , 5.91 ( d , j=4.7 hz , 1.5 h ; ri 1-ch ) , 5.90 ( d , j=4.9 hz , 1.5 h ; ri 1-ch ) , 5.75 ( d , j=8.1 hz , 1.5 h ; u ch ) , 5.72 ( d , j=8.1 hz , 1.5 h ; u ch ) , 5.21 ( t , j=5.2 hz , 3 h ; u 3-ch ) 5.034.97 ( m , 3 h ; c 3-ch ) , 4.52 ( s , 6 h ; hub - ch2o ) , 4.454.23 ( m , 18 h ; poch2ch2cn + u 5- ch2 + c 4-ch + u 4-ch ) , 4.214.19 ( m , 6 h ; suc - och2 ) , 4.15 ( br t , j=4.3 hz , 1.5 h ; u 2-ch ) , 4.14 ( br t , j=4.4 hz , 1.5 h ; u 2-ch ) , 4.04 ( dd , j=4.9 , 1.3 hz , 1.5 h ; c 2-ch ) , 4.03 ( dd , j=5.3 , 1.3 hz , 1.5 h ; c 2-ch ) , 3.953.91 ( m , 3 h ; 5-chh ) , 3.783.73 ( m , 3 h ; 5-chh ) , 3.67 ( t , j=4.8 hz , 6 h ; ch2o ) , 3.653.59 ( m , 84 h ; ch2o ) , 3.53 ( s , 4.5 h ; 2-och3 ) , 3.50 ( s , 4.5 h ; 2-och3 ) , 3.39 ( s , 9 h ; 2-och3 ) , 2.852.82 ( m , 6 h ; ch2cn ) , 2.722.69 ( m , 6 h ; suc ch2ch2 ) , 2.672.64 ( m , 6 h ; suc ch2ch2 ) , 2.17 ppm ( s , 9 h ; ac ch3 ) ; c nmr ( 126 mhz , cdcl3cd3od 2:1 v / v ) : =172.40 ( 3 c ; c = o ) , 171.75 ( 1.5 c ; c = o ) , 171.71 ( 1.5 c ; c = o ) , 171.56 ( 3 c ; c = o ) , 164.15 ( 3 c ; u / c c ) , 162.83 ( 3 c ; u / c c ) , 156.09 ( 3 c ; c c ) , 150.52 ( 3 c ; u c ) , 145.39 ( 3 c ; c ch ) , 140.21 ( 3 c ; u 6-ch ) , 138.47 ( 3 c ; hub c ) , 126.40 ( 3 c ; hub ch ) , 117.03 ( 1.5 c ; cn ) , 116.96 ( 1.5 c ; cn ) , 102.79 ( 1.5 c ; u 5-ch ) , 102.73 ( 1.5 c ; u 5-ch ) , 97.40 ( 1.5 c ; c ch ) , 97.34 ( 1.5 c ; c
ch ) , 89.22 ( 1.5 c ; c 1-ch ) , 89.10 ( 1.5 c ; c 1-ch ) , 88.08 ( 1.5 c ; u 1-ch ) , 88.02 ( 1.5 c ; u 1-ch ) , 83.2983.19 ( m , 3 c ; u 4-ch ) , 82.17 ( 3 c ; c 2-ch ) , 81.09 ( 1.5 c ; u 2-ch ) , 81.04 ( 1.5 c ; u 2-ch ) , 80.0879.97 ( m , 3 c ; c
4-ch ) , 74.5074.42 ( m , 3 c ; c 3-ch ) , 72.93 ( 3 c ; hub - ch2o ) , 70.35 ( 39 c ; ch2o ) , 70.18 ( 3 c ; u 3-ch ) , 69.43 ( 3 c ; ch2o ) , 68.87 ( 3 c ; ch2o ) , 66.70 ( br , 3 c ; u 5-ch2 ) , 63.91 ( 3 c ; sucoch2 ) , 63.1463.07 ( m , 3 c ; poch2ch2cn ) , 59.65 ( 3 c ; c 5-ch2 ) , 58.81 ( 3 c ; 2-och3 ) , 58.57 ( 1.5 c ; 2-och3 ) , 58.54 ( 1.5 c ; 2-och3 ) , 28.76 ( 6 c ; suc ch2 ) , 24.24 ( 3 c ; ac ch3 ) , 19.2219.10 ppm ( m , 3 c , ch2cn ) ; p nmr ( 202 mhz , cdcl3cd3od 2:1 v / v ) : =67.81 ( 0.44 p ) , 67.59 ppm ( 0.56 p ) ; ms ( maldi - tof+ ) : m / z calcd for [ c144h214n18nao72p3s3]=3537.20 ; found : 3538.3 [ 10+h ] .
tris(mupsmcpsmcpsmapsmupsmu - oh ) homostar ( 21)typical chain extension cycle : tris(ho-5-mer ) homostar 18 ( 1.286 g , 0.171 mmol ) was dissolved in dmf ( 4 ml ) to which was added ch3cn ( 20 ml ) and the solution evaporated in vacuo ; this was repeated with dmf ( 2 ml ) plus ch3cn ( 20 ml ) , and finally with neat ch3cn ( 20 ml ) .
phosphoramidite 6 ( 585 mg , 0.769 mmol , 4.5 equiv ) was then added to the residue followed by 0.25 m ett in ch3cn ( 6.2 ml , 1.55 mmol , 9 equiv ) .
after 35 min pads ( 465 mg , 1.55 mmol , 9 equiv ) and pyridine ( 6.2 ml ) were added , and after a further 35 min the reaction was diluted into ch3oh ch3cn ( 3:17 v / v ) and poured into the osn rig .
once 12 diavolumes had permeated , the retentate was evaporated to give crude 5-dmtr homostar 20 ( 1.779 g ) as a brown glass .
partially purified tris(dmtro-6-mer ) homostar 20 ( 1.708 g ) was placed in ch2cl2 ( 28 ml ) , to which was added pyrrole ( 0.48 ml ) then dca ( 0.28 ml ) . after 45 min
the mixture was diluted with ch3cn ( 100 ml ) and the liquid concentrated until all the ch2cl2 had evaporated .
to this solution was then added ch3oh ( 20 ml ) , the solution was diluted with further ch3oh ch3cn ( 3:17 v / v ) containing pyridinium.dca ( 0.5 vol % ) and 5 diavolumes were permeated .
the flux was observed to drop significantly , so this was followed by 10 diavolumes ch3oh ch3cn ( 1:4 v / v ) when the flux improved .
the retentate was evaporated to dryness , and the residual glass was re - dissolved in ch2cl2ch3oh ( 10 ml ) .
the solution was added dropwise to briskly stirred diethyl ether ( 300 ml ) , and the precipitate collected to afford tris(ho-6-mer ) homostar 21 ( 1.394 g , 98 % ) as a brown powder .
p nmr ( 202 mhz , cdcl3-cd3od 2:1 v / v ) : =67.867.1 ppm ( m , 15 p ) ; ms ( maldi - tof+ ) : m / z calcd for [ c330h429n66nao153p15s15 ] : 8734.0 ; found : 8728 [ 21+na ] .
chemical shifts in ppm are referenced with respect to residual solvent signals : h ( chcl3 ) 7.25 ppm , h ( chd2od ) 3.31 ppm , h ( cd3cochd2 ) 2.05 ppm ; c ( cdcl3 ) 77.50 ppm , c ( cd3od ) 49.15 ppm , c ( cd3cochd2 ) 29.92 ppm .
the splitting patterns for h nmr spectra are denoted as follows ; s ( singlet ) , d ( doublet ) , t ( triplet ) , q ( quartet ) , quin ( quintet ) , m ( multiplet ) , br ( broad ) and combinations thereof .
c nmr assignments ( c , ch , ch2 and ch3 ) and h nmr assignments were established with the aid of dept-135 , hsqc and cosy experiments .
molecular fragments not abbreviated in main text are denoted as follows : u , uracil ; c , cytosine ; ri , ribose ; suc , succinate ; hub , c6h3(ch2or)3 .
nmr spectrscopy of small dmtr derivatives was conducted in the presence of either a small amount of et3n or of pyridine .
mass spectra were recorded on micromass maldi micro mx , or micromass lct premier ( esi ) mass spectrometers .
other reagents were purchased from sigma - aldrich ltd . and used as supplied , except where specified .
dichloromethane , acetonitrile , thf and dmf were dried and stored over baked 4 molecular sieves .
triethylamine , diethyl ether , methanol , isopropanol and n - methyl imidazole were used as supplied .
flash chromatography was conducted in a 9 cm diameter , porosity 3 glass sinter funnel : geduran ( si 60 ) from merck was used for normal phase columns , and merck silanised silica for reverse phase columns .
thin - layer chromatography was carried out using merck silica gel 60 f254 aluminium - backed plates ; compounds were visualised using uv light or kmno4 stain .
solid phase oligonucleotide synthesis ( spos ) was carried out on a ge akta oligopilot 10 , using preloaded 2ome u primer support 200 and manufacturer s standard protocols on a 30 mol scale .
cleavage from solid support and deprotection of nucleobases was carried out in 0.88 aqueous ammonia at 55 c for 16 h.
tris-1,3,5-{-[2-o - methyl-5-o-(4,4-dimethoxytriphenylmethyl)uridine-3-o - succinyloxy]octa(ethylene glycol)--oxymethyl}benzene ( 3 ) : compound 1 ( 1.125 g , 1.00 mmol ) was co - evaporated from ch3cn ( 315 ml ) , re - dissolved in ch2cl2 ( 7 ml ) and a dropping funnel was fitted to the flask .
2-o - methyl-3-o - succinyl-5-o-(4,4-dimethoxytriphenylmethyl)uridine , triethylammonium salt ( 2 , 3.047 g , 4.00 mmol ) was co - evaporated from thf ( 350 ml ) , then re - dissolved in ch2cl2 ( 14 ml ) and n - methylimidazole ( 0.63 ml , 7.9 mmol ) then 2,6-dichlorobenzoyl chloride ( dcbcl , 0.54 ml , 3.77 mmol ) were added . after stirring for 20 min ,
the activated succinate solution was transferred to the dropping funnel , rinsing out the flask with further ch2cl2 ( 5 ml ) , and this solution slowly added to homostar 1 over 45 min . after stirring over night
the aqueous layer was back - extracted with small portions of ch2cl2 ( 50 ml3 ) , the combined organic layers dried over na2so4 , and the solvent stripped off in vacuo .
the residual foam may be purified chromatographically by fractionation through a column of silanised silica , eluting with a gradient of ch3cn water ( 3:7 to 8:2 v / v containing 0.5 % sat .
chcl3 1:9 + trace et3n ) 0.56 ; h nmr ( 400 mhz , cdcl3 ) : =7.88 ( d , j=8.2 hz , 3 h ; u ch ) , 7.387.36 ( m , 6 h ; dmtr ch ) , 7.32 ( t , j=7.5 hz , 6 h ; dmtr ch ) , 7.297.24 ( m , 18 h ; hub ch + dmtr ch ) , 6.86 ( d , j=8.9 hz , 12 h ; dmtr ch ) , 6.04 ( d , j=3.7 hz , 3 h ; 1-ch ) , 5.33 ( d , j=8.2 hz , 3 h ; u ch ) , 5.29 ( t , j=5.6 hz , 3 h ; 3-ch ) , 4.55 ( s , 6 h ; hub - ch2o ) , 4.264.24 ( m , 9 h ; 4-ch + suc - och2 ) , 4.10 ( dd , j=5.1 , 3.7 hz , 3 h ; 2-ch ) , 3.81 ( s , 18 h ; och3 ) , 3.713.58 ( m , 93 h ; ch2o + 5-chh ) , 3.483.44 ( m , 12 h ; 2-och3 + 5-chh ) , 2.732.66 ppm ( m , 12 h ; suc ch2 ) ; c nmr ( 101 mhz , cdcl3 ) : =171.98 ( 3 c ; suc c = o ) , 171.53 ( 3 c ; suc c = o ) , 163.29 ( 3 c ; u
c ) , 139.78 ( 3 c ; u 6-ch ) , 138.57 ( 3 c ; hub c ) , 134.98 ( 3 c ; dmtr c ) , 134.86 ( 3 c ; dmtr c ) , 130.17 ( 6 c ; dmtr ch ) , 130.09 ( 6 c ; dmtr ch ) , 128.08 ( 12 c ; dmtr ch ) , 127.24 ( 3 c ; dmtr ch ) , 126.32 ( 3 c ; hub ch ) , 113.33 ( 12 c ; dmtr ch ) , 102.51 ( 3 c ; u 5-ch ) , 87.39 ( 3 c ; dmtr
c ) , 87.13 ( 3 c ; 1-ch ) , 82.18 ( 3 c ; ri ch ) , 81.03 ( 3 c ; ri ch ) , 73.06 ( 3 c ; hub - ch2o ) , 70.54 ( 39 c ; ch2o ) , 70.36 ( 3 c ; ri ch ) , 69.51 ( 3 c ; ch2o ) , 69.02 ( 3 c ; ch2o ) , 63.94 ( 3 c ; ch2o ) , 61.56 ( 3 c ; 5-ch2 ) , 59.03 ( 3 c ; 2-och3 ) , 55.26 ( 6 c ; dmtr och3 ) , 28.88 ( 3 c ; suc ch2 ) , 28.83 ppm ( 3 c ; suc ch2 ) ; ms ( maldi - tof+ ) : m / z calcd for [ c162h210n6nao57 ] : 3175.4 ; found : 3176 [ 3+na ]
. tris-1,3,5-[-(2-o - methyluridine-3-o - succinyloxy)octa(ethylene glycol)--oxymethyl]benzene ( 4 ) : the crude tris(dmtr - mu ) homostar 3 ( 4.438 g from the above procedure ) was dissolved in ch2cl2 ( 40 ml ) and pyrrole ( 1.39 ml , 19.6 mmol ) was added .
dichloroacetic acid was then added in aliquots ( 0.40 ml , 4.8 mmol ) until a strong orange colour remained , and then dissipated over 20 min ; four aliquots were required to overwhelm buffering of the crude dmtr ether and tlc confirmed complete unblocking of intermediate 3 .
the aqueous layer was back - extracted with ch2cl2 ( 50 ml4 ) , organic layers combined , dried over na2so4 and the solvent stripped off under reduced pressure .
the residue was fractionated through a column of silica gel ( 180 ml ) in a large sinter funnel , eluting with a gradient of ch3oh
bands containing dcb - ester 5 ( 409 mg ) , mixed with some product , and compound 4 ( 1.644 g , 80 % ) were isolated as colourless gums .
rf ( ch3oh chcl3 1:9 ) 4 0.35 ; 5 0.51 ; h nmr ( 400 mhz , cdcl3 ) : =9.53 ( br d , j=2.3 , 3 h ; u 4-nh ) , 7.85 ( d , j=8.1 hz , 3 h ; u 6-ch ) , 7.23 ( s , 3 h ; hub ch ) , 5.85 ( d , j=5.1 hz , 3 h ; 1-ch ) , 5.76 ( dd , j=8.0 , 2.0 hz , 3 h ; u 5-ch ) , 5.32 ( t , j=4.6 hz , 3 h ; 3-ch ) 4.55 ( s , 6 h ; hub - ch2o ) , 4.26 ( dt , j=5.4 , 2.0 hz , 6 h ; suc - och2 ) , 4.224.19 ( m , 6 h ; 4-ch + 2-ch ) , 3.94 ( br d , j=12.0 hz , 3 h ; 5-chh ) , 3.79 ( br dd , j=12.3 , 4.0 hz , 3 h ; 5-chh ) , 3.723.61 ( m , 90 h ; ch2o ) , 3.43 ( s , 9 h ; 2-och3 ) , 2.762.68 ppm ( m , 12 h ; suc ch2ch2 ) ; c nmr ( 101 mhz , cdcl3 ) : =172.08 ( 3 c ; suc c = o ) , 171.68 ( 3 c ; suc c = o ) , 163.92 ( 3 c ; u c ) , 150.75 ( 3 c ; u c ) , 141.22 ( 3 c ; u 6-ch ) , 138.51 ( 3 c ; hub c ) , 126.29 ( 3 c ; hub ch ) , 102.64 ( 3 c ; u 5-ch ) , 88.69 ( 3 c ; 1-ch ) , 83.18 ( 3 c ; 2/4-ch ) , 81.43 ( 3 c ; 2/4-ch ) , 73.00 ( 3 c ; hub - ch2o ) , 70.96 ( 3 c ; 3-ch ) , 70.48 ( 39 c ; ch2o ) , 69.46 ( 3 c ; ch2o ) , 68.96 ( 3 c ; ch2o ) , 63.90 ( 3 c ; suco - ch2 ) , 61.15 ( 3 c ; 5-ch2 ) , 58.90 ( 3 c ; 2-och3 ) , 28.95 ppm ( 6 c ; suc ch2ch2 ) ; ms ( maldi - tof+ ) : m / z calcd for [ c99h156n6nao51 ] : 2268.97 ; found : 2269.0 [ 4+na ] .
tris-1,3,5-{-(2-o - me-5-o-{[2-o - me-5-o-(dmtr)-4-n - acetylcytosin-3-yl](2-cyanoethyloxy)thiophosphoryl}uridinyl-3-o - succinyloxy)octa(ethylene glycol)--oxymethyl}benzene , tris(mupsmc - odmtr ) homostar ( 7 ) : tris(2-methyluridine ) homostar 4 ( 422 mg , 0.188 mmol ) and compound 6 ( 678 mg , 0.846 mmol , 4.5 equiv ) were co - evaporated from ch3cn ( 310 ml ) in vacuo . to the residue was added 0.25 m ett in ch3cn ( 6.77 ml , 1.69 mmol , 9 equiv ) , and after 40 min , pads ( 1.71 g , 5.65 mmol , 30 equiv ) and pyridine ( 6.8 ml ) were added . after a further 60 min
the solvent was stripped off under reduced pressure and the residue fractionated through a column of silanised silica , eluting with a gradient of water
the resultant emulsion was extracted with ch2cl2 ( 100 ml4 ) , the organic layer dried over na2so4 , and then evaporated to dryness .
the appropriate fractions were extracted as before to afford compound 7 ( 538 mg , 64 % ) .
rf ( ch3oh ch2cl2 1:9 ) 0.41 ; intermediate tris(phosphite triester ) 0.54 ; h nmr ( 400 mhz , d6-acetone ) : =10.38 ( br s , 1.5 h ; nh ) , 10.25 ( s , 1.5 h ; nh ) , 10.19 ( s , 1.5 h ; nh ) , 10.15 ( br s , 1.5 h ; nh ) , 8.49 ( d , j=7.4 hz , 3 h ; c ch ) , 7.75 ( d , j=8.2 hz , 1.5 h ; u
ch ) , 7.64 ( d , j=8.2 hz , 1.5 h ; u ch ) , 7.547.51 ( m , 6 h ; dmtr ch ) , 7.427.36 ( m , 18 h ; dmtr ch ) , 7.337.30 ( m , 3 h ; dmtr ch ) , 7.28 ( s , 3 h ; hub ch ) , 7.13 ( d , j=7.2 hz , 1.5 h ; c ch ) , 7.12 ( d , j=7.4 hz , 1.5 h ; c ch ) , 6.976.93 ( m , 12 h ; dmtr ch ) , 6.076.04 ( m , 3 h ; 1-ch ) , 5.995.96 ( m , 3 h ; 1-ch ) , 5.71 ( d , j=7.7 hz , 1.5 h ; u ch ) , 5.70 ( d , j=7.8 hz , 1.5 h ; u ch ) , 5.375.26 ( m , 2 h ; 23-ch ) , 4.56 ( s , 6 h ; hub - ch2o ) , 4.534.37 ( m , 9 h ; u 4-ch + c 4-ch + pochhch2cn ) , 4.364.15 ( m , 21 h ; u 2-ch + c
2-ch + 5-ch2 + pochhch2cn + suc - och2 ) , 3.84 ( s , 9 h ; dmtr och3 ) , 3.83 ( s , 9 h ; dmtr och3 ) , 3.693.53 ( m , 105 h ; ch2o + 5-ch2 + 2-och3 ) , 3.41 ( s , 4.5 h ; 2-och3 ) , 3.40 ( s , 4.5 h ; 2-och3 ) , 3.01 ( t , j=7.2 hz , 3 h ; ch2cn ) , 2.92.87 ( m , 3 h ; ch2cn ) , 2.762.73 ( m , 6 h ; suc ch2 ) , 2.702.67 ( m , 6 h ; suc ch2 ) , 2.25 ( s , 4.5 h ; ac ch3 ) , 2.24 ppm ( s , 4.5 h ; ac ch3 ) ; c nmr ( 101 mhz , d6-acetone ) : =171.89 ( 3 c ; c = o ) , 171.45 ( 3 c ; c = o ) , 170.66 ( 3 c ; c = o ) , 163.09 ( 3 c ; u / c c ) , 162.68 ( 1.5 c ; u / c c ) , 162.64 ( 1.5 c ; u / c c ) , 158.92 ( 6 c ; dmtr c ) , 154.71 ( 1.5 c ; c
c ) , 154.60 ( 1.5 c ; c c ) , 150.47 ( 1.5 c ; u c ) , 150.44 ( 1.5 c ; u c ) , 144.44 ( 1.5 c ; c
ch ) , 144.30 ( 1.5 c ; c ch ) , 144.27 ( 1.5 c ; dmtr
c ) , 140.02 ( 3 c ; u 6-ch ) , 139.00 ( 3 c ; hub c ) , 135.43 ( 1.5 c ; dmtr
c ) , 135.33 ( 1.5 c ; dmtr c ) , 135.19 ( 1.5 c ; dmtr
c ) , 130.27 ( 6 c ; dmtr ch ) , 130.18 ( 6 c ; dmtr ch ) , 128.48 ( 3 c ; dmtr ch ) , 128.40 ( 3 c ; dmtr ch ) , 128.02 ( 6 c ; dmtr ch ) , 127.18 ( 3 c ; dmtr ch ) , 125.70 ( 3 c ; hub ch ) , 117.59 ( 1.5 c ; cn ) , 117.31 ( 1.5 c ; cn ) , 113.27 ( 12 c ; dmtr ch ) , 102.65 ( 1.5 c ; u 5-ch ) , 102.52 ( 1.5 c ; u 5-ch ) , 96.15 ( 3 c ; c ch ) , 88.80 ( 1.5 c ; 1-ch ) , 88.51 ( 1.5 c ; 1-ch ) , 88.04 ( 1.5 c ; 1-ch ) , 87.99 ( 1.5 c ; 1-ch ) , 87.08 ( 1.5 c ; dmtr
c ) , 87.06 ( 1.5 c ; dmtr c ) , 82.09 ( 1.5 c ; ri ch ) , 81.78 ( 1.5 c ; ri ch ) , 80.91 ( 3 c ; ri ch ) , 80.79 ( 3 c ; ri ch ) , 80.1580.00 ( m , 3 c ; ri ch ) , 73.51 ( 1.5 c ; ri
ch ) , 73.28 ( 1.5 c ; ri ch ) , 72.54 ( 3 c ; hub - ch2o ) , 70.58 ( 3 c ; ri ch ) , 70.35 ( 39 c ; ch2 ) , 69.64 ( 3 c ; ch2o ) , 68.72 ( 3 c ; ch2o ) , 67.4267.10 ( 3 c ; u 5-ch2 ) , 63.7563.48 ( m , 6 c ; ch2o + poch2ch2cn ) , 60.57 ( 1.5 c ; c
5-ch2 ) , 60.49 ( 1.5 c ; c 5-ch2 ) , 58.40 ( 1.5 c ; 2-och3 ) , 58.33 ( 1.5 c ; 2-och3 ) , 58.13 ( 1.5 c ; 2-och3 ) , 57.83 ( 1.5 c ; 2-och3 ) , 54.81 ( 3 c ; dmtr och3 ) , 54.79 ( 3 c ; dmtr och3 ) , 28.67 ( 6 c ; suc ch2 ) , 24.13 ( 1.5 c ; ac ch3 ) , 24.05 ( 1.5 c ; ac ch3 ) , 19.0718.90 ppm
( m , 3 c ; ch2cn ) ; p nmr ( 162 mhz , d6-acetone ) =67.33 ( 0.39 p ) , 67.11 ppm ( 0.61 p ) ; ms ( maldi - tof+ ) : m / z calcd for [ c207h269n18nao79p3s3 ] : 4484.59 ; found : 4484.1 [ 7+na+h2o ] .
tris(mupsmc - oh ) homostar ( 10 ) : tris(dmtro-2-mer ) homostar 7 ( 192 mg , 43 mol ) was placed in ch2cl2 ( 1 ml ) , to which pyrrole ( 35 l ) then dca ( 35 l ) were added .
after 60 min the reaction was complete by tlc and 1 m triethylammonium bicarbonate ( teab , 0.5 ml ) was added , followed by sufficient ch3cn to give a clear solution .
the solution was concentrated at reduced pressure until all ch2cl2 had evaporated , then silanised silica ( 10 ml ) was added to the remaining solution followed by the slow addition of water ( 90 ml ) with gentle swirling , plus 1 m teab ( 1 ml ) .
the silica was collected in a glass sinter funnel , and the pad was washed with water ( 50 ml ) , then ch3cn water ( 1:3 v / v , 160 ml plus 1.5 ml teab ) and the filtrate was discarded . next the silica was washed with ch3cn ( 150 ml ) and the filtrate evaporated to dryness .
the residue ( 156 mg ) was taken up in chcl3 ( 20 ml ) and to the swirled solution was added normal phase silica ( 10 ml ) .
the silica was collected in a glass sinter funnel , the pad was washed with further chcl3 ( 130 ml ) and the filtrate discarded . finally the silica was washed with ch3oh chcl3 ( 1:9 v / v , 150 ml ) and the filtrate evaporated to dryness to afford compound 10 ( 118 mg , 77 % ) .
chcl3 1:9 ) 0.19 ; h nmr ( 500 mhz , cdcl3cd3od 2:1 v / v ) : =8.42 ( d , j=7.5 hz , 1.5 h ; c ch ) , 8.41 ( d , j=7.6 hz , 1.5 h ; c ch ) , 7.63 ( d , j=8.1 hz , 1.5 h ; u
ch ) , 7.402 ( d , j=7.5 hz , 1.5 h ; c ch ) , 7.397 ( d , j=7.6 hz , 1.5 h ; c
ch ) , 7.21 ( s , 3 h ; hub ch ) , 5.98 ( d , j=3.7 hz , 3 h ; ri 1-ch ) , 5.91 ( d , j=4.7 hz , 1.5 h ; ri 1-ch ) , 5.90 ( d , j=4.9 hz , 1.5 h ; ri 1-ch ) , 5.75 ( d , j=8.1 hz , 1.5 h ; u ch ) , 5.72 ( d , j=8.1 hz , 1.5 h ; u
ch ) , 5.21 ( t , j=5.2 hz , 3 h ; u 3-ch ) 5.034.97 ( m , 3 h ; c 3-ch ) , 4.52 ( s , 6 h ; hub - ch2o ) , 4.454.23 ( m , 18 h ; poch2ch2cn + u 5- ch2 + c 4-ch + u 4-ch ) , 4.214.19 ( m , 6 h ; suc - och2 ) , 4.15 ( br t , j=4.3 hz , 1.5 h ; u 2-ch ) , 4.14 ( br t , j=4.4 hz , 1.5 h ; u 2-ch ) , 4.04 ( dd , j=4.9 , 1.3 hz , 1.5 h ; c 2-ch ) , 4.03 ( dd , j=5.3 , 1.3 hz , 1.5 h ; c 2-ch ) , 3.953.91 ( m , 3 h ; 5-chh ) , 3.783.73 ( m , 3 h ; 5-chh ) , 3.67 ( t , j=4.8 hz , 6 h ; ch2o ) , 3.653.59 ( m , 84 h ; ch2o ) , 3.53 ( s , 4.5 h ; 2-och3 ) , 3.50 ( s , 4.5 h ; 2-och3 ) , 3.39 ( s , 9 h ; 2-och3 ) , 2.852.82 ( m , 6 h ; ch2cn ) , 2.722.69 ( m , 6 h ; suc ch2ch2 ) , 2.672.64 ( m , 6 h ; suc ch2ch2 ) , 2.17 ppm ( s , 9 h ; ac ch3 ) ; c nmr ( 126 mhz , cdcl3cd3od 2:1 v / v ) : =172.40 ( 3 c ; c = o ) , 171.75 ( 1.5 c ; c = o ) , 171.71 ( 1.5 c ; c = o ) , 171.56 ( 3 c ; c = o ) , 164.15 ( 3 c ; u / c c ) , 162.83 ( 3 c ; u / c c ) , 156.09 ( 3 c ; c
c ) , 150.52 ( 3 c ; u c ) , 145.39 ( 3 c ; c ch ) , 140.21 ( 3 c ; u 6-ch ) , 138.47 ( 3 c ; hub c ) , 126.40 ( 3 c ; hub ch ) , 117.03 ( 1.5 c ; cn ) , 116.96 ( 1.5 c ; cn ) , 102.79 ( 1.5 c ; u 5-ch ) , 102.73 ( 1.5 c ; u 5-ch ) , 97.40 ( 1.5 c ; c ch ) , 97.34 ( 1.5 c ; c
ch ) , 89.22 ( 1.5 c ; c 1-ch ) , 89.10 ( 1.5 c ; c 1-ch ) , 88.08 ( 1.5 c ; u 1-ch ) , 88.02 ( 1.5 c ; u 1-ch ) , 83.2983.19 ( m , 3 c ; u 4-ch ) , 82.17 ( 3 c ; c 2-ch ) , 81.09 ( 1.5 c ; u 2-ch ) , 81.04 ( 1.5 c ; u 2-ch ) , 80.0879.97 ( m , 3 c ; c 4-ch ) , 74.5074.42 ( m , 3 c ; c 3-ch ) , 72.93 ( 3 c ; hub - ch2o ) , 70.35 ( 39 c ; ch2o ) , 70.18 ( 3 c ; u 3-ch ) , 69.43 ( 3 c ; ch2o ) , 68.87 ( 3 c ; ch2o ) , 66.70 ( br , 3 c ; u 5-ch2 ) , 63.91 ( 3 c ; sucoch2 ) , 63.1463.07 ( m , 3 c ; poch2ch2cn ) , 59.65 ( 3 c ; c
5-ch2 ) , 58.81 ( 3 c ; 2-och3 ) , 58.57 ( 1.5 c ; 2-och3 ) , 58.54 ( 1.5 c ; 2-och3 ) , 28.76 ( 6 c ; suc ch2 ) , 24.24 ( 3 c ; ac ch3 ) , 19.2219.10 ppm ( m , 3 c , ch2cn ) ; p nmr ( 202 mhz , cdcl3cd3od 2:1 v / v ) : =67.81 ( 0.44 p ) , 67.59 ppm ( 0.56 p ) ; ms ( maldi - tof+ ) : m / z calcd for [ c144h214n18nao72p3s3]=3537.20 ; found : 3538.3 [ 10+h ] .
tris(mupsmcpsmcpsmapsmupsmu - oh ) homostar ( 21)typical chain extension cycle : tris(ho-5-mer ) homostar 18 ( 1.286 g , 0.171 mmol ) was dissolved in dmf ( 4 ml ) to which was added ch3cn ( 20 ml ) and the solution evaporated in vacuo ; this was repeated with dmf ( 2 ml ) plus ch3cn ( 20 ml ) , and finally with neat ch3cn ( 20 ml ) .
phosphoramidite 6 ( 585 mg , 0.769 mmol , 4.5 equiv ) was then added to the residue followed by 0.25 m ett in ch3cn ( 6.2 ml , 1.55 mmol , 9 equiv ) .
after 35 min pads ( 465 mg , 1.55 mmol , 9 equiv ) and pyridine ( 6.2 ml ) were added , and after a further 35 min the reaction was diluted into ch3oh ch3cn ( 3:17 v / v ) and poured into the osn rig .
once 12 diavolumes had permeated , the retentate was evaporated to give crude 5-dmtr homostar 20 ( 1.779 g ) as a brown glass .
partially purified tris(dmtro-6-mer ) homostar 20 ( 1.708 g ) was placed in ch2cl2 ( 28 ml ) , to which was added pyrrole ( 0.48 ml ) then dca ( 0.28 ml ) . after 45 min
the mixture was diluted with ch3cn ( 100 ml ) and the liquid concentrated until all the ch2cl2 had evaporated . to this solution
was then added ch3oh ( 20 ml ) , the solution was diluted with further ch3oh ch3cn ( 3:17 v / v ) containing pyridinium.dca ( 0.5 vol % ) and 5 diavolumes were permeated .
the flux was observed to drop significantly , so this was followed by 10 diavolumes ch3oh ch3cn ( 1:4 v / v ) when the flux improved .
the retentate was evaporated to dryness , and the residual glass was re - dissolved in ch2cl2ch3oh ( 10 ml ) .
the solution was added dropwise to briskly stirred diethyl ether ( 300 ml ) , and the precipitate collected to afford tris(ho-6-mer ) homostar 21 ( 1.394 g , 98 % ) as a brown powder .
p nmr ( 202 mhz , cdcl3-cd3od 2:1 v / v ) : =67.867.1 ppm ( m , 15 p ) ; ms ( maldi - tof+ ) : m / z calcd for [ c330h429n66nao153p15s15 ] : 8734.0 ; found : 8728 [ 21+na ] .
as a service to our authors and readers , this journal provides supporting information supplied by the authors .
such materials are peer reviewed and may be re - organized for online delivery , but are not copy - edited or typeset . technical support issues arising from supporting information ( other than missing files ) should be addressed to the authors
Output:
| due to the discovery of rnai , oligonucleotides ( oligos ) have re - emerged as a major pharmaceutical target that may soon be required in ton quantities . however , it is questionable whether solid - phase oligo synthesis ( spos ) methods can provide a scalable synthesis . liquid - phase oligo synthesis ( lpos ) is intrinsically scalable and amenable to standard industrial batch synthesis techniques . however , most reported lpos strategies rely upon at least one precipitation per chain extension cycle to separate the growing oligonucleotide from reaction debris .
precipitation can be difficult to develop and control on an industrial scale and , because many precipitations would be required to prepare a therapeutic oligonucleotide , we contend that this approach is not viable for large - scale industrial preparation .
we are developing an lpos synthetic strategy for 2-methyl rna phosphorothioate that is more amenable to standard batch production techniques , using organic solvent nanofiltration ( osn ) as the critical scalable separation technology .
we report the first lpos - osn preparation of a 2-me rna phosphorothioate 9-mer , using commercial phosphoramidite monomers , and monitoring all reactions by hplc , 31p nmr spectroscopy and ms . |
PubmedSumm118630 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: gap nonunion presents a major challenge to the orthopedic surgeon , especially when associated with infection , old or active osteomyelitis , and multiple previous surgeries.1 management of the gap nonunion is technically difficult , time - consuming , physically and psychologically demanding for the patient with unpredictable clinical outcome .
the problem involves bridging or regenerating areas of bone loss while maintaining limb length and alignment.2 open fractures with bone loss are most common in the tibia due to its subcutaneous anatomical site , and a number of patients have secondary bone loss after surgical debridement of the necrotic bone or osteomyelitis.2 nonunion with infection , bone loss , or both , represents a more complex problem and is better managed with a vascularized fibular graft , free fibular graft , bone transport , or sometimes even amputation.34 the nonunion may persist despite a series of reconstructive procedures , with external fixation , internal fixation ( plate or intramedullary rods ) , bone grafting , plastic surgery , and ilizarov frame application .
the patient may require multiple surgeries and sometimes the surgeon is left with no option , but secondary amputation or disarticulation .
transposition of the ipsilateral fibula to the tibia ( fibula pro tibia ) was suggested by hahn in 1884 , and was first used successfully by huntington in 1903.56 subsequently , several authors have used fibular centralization in cases of posttraumatic and post - infective tibial defects , osteomyelitis , congenital deformity , and tumors.1711 the fibula is mainly a cortical bone and provides mechanical strength . in this procedure , the fibula is transferred to the tibia as a pedicle graft . due to retained blood supply to one end of the transplant , the graft easily takes up and hypertrophies upon weightbearing over a period of time.67 the aim of this retrospective analysis is to report the midterm results , problems and obstacles with ipsilateral fibular transposition for reconstruction of tibial defects .
we retrospectively reviewed the results of 22 patients operated with tibialization of the fibula , operated between 1998 and 2008 .
all these patients had segmental tibial loss ( more than 6 cm ) that occurred due to open fracture of the tibia ( n=14 ) , chronic hematogenous osteomyelitis with or without sequestrum ( n=3 ) and following failed / infected previous implant surgery in closed fracture of tibia ( n=5 ) .
all these patients had intact or well - united fibula and intact sensation in the sole of the foot .
there were 20 males and two females with a mean age of 26.8 years ( range 16 34 years ) .
average time of the huntington 's procedure after the initial trauma was 20 months ( range 15 - 30 months ) .
all the patients were subjected to the routine investigations for pre - anaesthetic checkup and the x - rays of the affected leg .
initially sequestrum and dead necrotic bone were removed and infection was managed by debridement and antibiotics .
all the operations were performed under general ( n=7 ) or regional anesthesia ( n=15 ) .
seven patients had two - stage procedures and in the remaining cases it was a single - stage procedure .
initially sequestrum and dead necrotic bone were removed and infection was managed by debridement and antibiotics . if soft tissues were adequately supple , a single - stage surgery was performed , whereas , in the presence of extensive scarring , particularly in the lateral compartment of the leg , a two stage surgery was preferred . in the two - stage procedure ,
the proximal end was tibialized in the first stage and the second stage was performed after six - to - eight weeks . through a lateral incision , 34 cm of the proximal fibula was exposed subperiosteally , above the level of the distal part of the proximal tibial fragment .
the peroneal nerve was not dissected routinely , except in two cases , where the site of the nonunion was in proximal one - third of fibula . through another anterior one - and - a - half - inch long incision ,
the distal lateral part of the proximal tibia was exposed and a shallow trough was made on this surface to fit the fibula for better contact .
the muscle and neurovascular structures in the anterior compartment were retracted anteriorly and the fibula was shifted into the trough and stabilized with two - to - three 4.5 mm ( n=16 ) cortical screws or 4 mm ( n=3 ) cancellous screws or kirschner 's wires ( n=3 ) . in the single - stage procedure ,
34 cm of the distal fibula was also exposed subperiosteally below the level of the proximal part of the distal tibial fragment , through a lateral incision . through another 4-cm long anterior incision
, the lateral surface of distal tibial fragment was exposed 2 3 cm below its tip , and a trough was made for fitting the fibula after lifting the neurovascular bundle and muscles anteriorly .
it was stabilized using two - to - three 4.5 mm ( n=16 ) cortical screws or 4 mm ( n=3 ) cancellous screws or kirschner 's wires ( n=3 ) . in two cases where the distal tibial fragment was small , an intramedullary pin through the calcaneum
, subtalar joints and ankle joint was used to fix the distal end of the fibula and apex of the distal tibial fragment .
the soft tissue and skin were sutured and a well - padded plaster cast was applied from the groin to the toe , with the knee in 5
10 flexion , the ankle in 5 external rotation , and the foot in the neutral position or as much dorsiflexed as possible , in cases where there was equinus deformity .
guarded weightbearing was started eight - to - ten weeks onward , when the radiological union was observed , and a full leg cast was converted to below leg cast after 16 20 weeks .
patients were followed up regularly and assessed clinicoradiologically for bone union , infection , and complications like nonunion of synostosis , implant failure , fracture of fibula , and so on .
bony union was said to have occurred when the authors observed the osseous bridging ( uninterrupted external bony borders ) between the fibula and tibia at the synostotic site , with no evidence of gap , in both the anteroposterior and lateral views of the x - rays .
patient satisfaction was assessed using a four - level scale ( subjective assessment was done whereby the patients were asked about their satisfaction level with the final outcome ) i.e. whether they were very satisfied , satisfied , fairly satisfied or dissatisfied ; and the pain score was assessed using a 10-point visual analog scale ( vas ) , where 1 represented no pain and 10 unbearable pain . in addition
the range of motion in the knee and ankle joint , with the associated deformities and shortening , were also taken into account .
the patients had nonunions with gaps ranging from 6 to 16 cm ( mean 11.3 cm ) .
fourteen patients had open tibial fractures , three had the sequelae of chronic osteomyelitis , and five had infected nonunion after nailing / plating for closed tibial fractures , requiring removal of the bony segments . in seven patients two - stage procedures were done , where the proximal fibula was shifted at the first stage , followed by a second - stage surgery , after six - to - eight weeks in the distal end .
the mean followup after fibular transposition was 5.38 years ( range 3 10 years ) .
the mean leg length discrepancy / shortening was 4 cm ( range 2 9 cm ) and the patients were advised suitable shoe raise for ambulation . in five patients ,
one patient had nonunion at the proximal synostotic site , even after grafting and refixation . however , this patient was mobile with brace and crutches .
the average time of union was 12.8 weeks ( range 8 21 weeks ) .
full weight bearing on the operated leg with ( n=14 ) or without ( n=8 ) walking aids , was achieved at average 16 months ( range 12 30 months ) .
radiographically , hypertrophy of the grafted fibula was observed in all the patients , and in some cases ( n=5 ) , the grafted fibula was as thick as the tibia on the opposite side [ figures 1 and 2 ] .
the infection healed in all but one patient , who had some drainage on and off . in one patient ,
the patient was re - operated upon and fixed with a thin diameter intramedullary rush nail , along with cancellous bone grafting .
another patient had screw cut out at the distal end , but could be managed well in the plaster and had malunion [ figure 3 ] .
one patient had a fractured fibula after full weightbearing , which was managed conservatively with an above - knee cast , and was united in a four - month period .
most of the patients were able to perform their day - to - day activities and routine work , although with some restriction in running , climbing stairs , and doing strenuous work .
no significant difference was found in terms of union , fibular hypertrophy , complications , patient satisfaction , and time of weightbearing , in patients with single - stage versus two - stage surgery . at the final followup
, ten patients were very satisfied , seven satisfied , and five fairly satisfied [ table 1 ] .
the results were evaluated on the basis of our observation that the patients with no pain , more walking distance without aid , less limb length discrepancy , good ankle and knee movements , and performing routine activities efficiently were more satisfied and vice versa .
roentgenograms showing ( a ) anteroposterior and lateral views a big gap in the tibia ; ( b ) the fibula was approximated and compressed to tibia above and below the defect with screws ; ( c ) hypertrophy of the fibula after six years , almost three times the original girth of the fibula ( d ) clinical photograph of patient showing weight bearing on hypertrophied fibula roentgenograms showing ( a ) anteroposterior view a large gap in distal tibia and nonunion of fibula with deformity ; ( b ) fibula medialized to tibia above the defect with two screws and in the distal part the deformity was corrected , bone grafted , and stabilized with kirschner wires ( removed in followup as they became symptomatic ) ; ( c ) hypertrophy of fibula after seven years ; ( d ) clinical photograph of same patient showing full weight bearing on hypertrophied fibula ( a ) roentgenogram anteroposterior and lateral views ( b ) clinical photograph of same patient showing complication as cut out of screw in a patient with a big tibial gap clinical details of the patients
gap nonunion of the tibia with infection and extensive scarring creates a challenging clinical situation for treatment .
the tibia is affected more than the fibula , because of its subcutaneous location , leading to either loss of segment or requiring removal of necrotic bony segment in the process of the treatment , the fibula , being covered by muscles all around , usually escapes segmental loss and also unites easily and takes its continuity back .
the option for treatment of such injuries includes a papineau type of cancellous bone grafting in patients with bone gap less than 4 cm , non - vascularized fibula graft from contralateral leg , microvascular fibular transfer , huntington 's procedure , and ilizarov technique .
the cancellous bone used in the papineau 's procedure provides limited mechanical strength.91213 the ilizarov technique involves bone transfer and compression - distraction to stimulate the nonunion site .
it is a prolonged , time - consuming procedure , with its own complications and obstacles.14 although early weightbearing is possible , and proper realignment of the limb can be achieved , the major drawback of this technique is that prolonged endurance with frame , is not very well accepted by patients with a significant pin track infection rate.215 the use of a free - vascularized fibular transfer from the contralateral limb adds morbidity to the normal limb , is time - consuming , and requires a specialized microsurgical team , which may not be available even in major centers.16 in extensively scarred tissue , considerable dissection of the posterior and lateral compartments to isolate the peroneal vessel is problematic and its anastomosis in such a leg is a gigantic task.1718 free fibular graft from the opposite side leg , in the presence of sepsis , may necrose and even if it survives , it will take a very long time to heal , with a poor functional outcome.9 additionally there is donor site morbidity .
the use of the avascular strut allograft is often limited by the available length of the resection , risk of nonunion , fracture , and infection , besides the fear of disease transmission.1019 the presence of infection and extensive soft - tissue loss can be a serious threat to the viability of the limb .
however , there has been much debate on the long term disability after amputation , as well as the cost of repeated prostheses .
medialization of the ipsilateral fibula ( huntington 's procedure ) can be performed by a trained orthopedic surgeon even in hospitals with moderate infrastructure . a large graft of the ipsilateral fibula raised on a pedicle of the peroneal artery , aligned and fixed to the tibia in its posterior long axis , provide a sound mechanical and biological basis for the union.20 the fibula
is surrounded by muscles all around and has abundant vascular supply from the nutrient branch of the peroneal artery and circular anastomosis of the musculoperiosteal vessels , which supports in its hypertrophy and union at the synostotic site.2021 when the fibula is subjected to more than normal weightbearing stresses , it undergoes hypertrophy and becomes an integral part of the static supporting architecture of the leg.7 the fibula placed centrally in the weightbearing axis in the medullary cavity of the tibia seems to be more biomechanically sound than synostosis of the fibula to the tibia in its lateral eccentric position , both in children and adults.21 however , in patients with extensive scarring and fibrosis , it is too difficult to mobilize the fibula centrally , without excessive periosteal stripping , thus jeopardizing the blood supply . furthermore , there is no need to touch or handle the scarred or infected gap area , as surgical incision and procedure is restricted away from the infected nonunion site .
even the area of circumferential scarring can be left as such , without performing a substantial plastic procedure like free flap or cross leg flap .
ipsilateral fibular transfer is an easy , simple , inexpensive biological procedure that does not require microvascular skills .
the reduction in volume of the lower leg that follows the anteromedial shift of the fibula makes skin closure easier , even in cases with scarred tissue .
the procedure is restricted to the same limb , unlike those cases in which the opposite fibula is used as a vascularized graft .
the shorter operating time and the fact that the graft retains its blood supply may help to reduce infection , improving its chances of union and accelerating the process of hypertrophy.1022 hutington in 1944 popularized a procedure for treatment of tibial defects in children , which he described it as a two - stage procedure.6 we opted for this procedure as a last resort and had good success in salvaging the limbs . in more than half of the cases we could perform the procedure in one stage , where there were supple soft tissues on the anterolateral part of the leg .
however , in cases of circumferential scarring and scarification on the anterolateral part , a two - staged procedure was preferred , as the fibula would need extensive release from the lateral surface , jeopardizing its blood supply.23 if it was medialized in the presence of a scar in this area there were chances of screw cut outs , which occurred in two patients in our series . in adults the hypertrophy of the fibula usually took a long time , as compared to children.24 therefore , they needed prolonged protective weightbearing .
they were advised to use a leg brace along with a stick , till union between the fibula and tibia occurred .
the procedure provided acceptable function to many patients and served as a good enough alternative to amputation , where there was adequate vascularity and intact sensation in the sole .
another drawback of this procedure was that these patients were not able to participate in strenuous activities like sports , due to the risk of fractures and a shortened limb , but they could do all their routine work at farms and public transportation , without the help of walking aids . since these cases have severe bone loss in scarred extremity , hence even after other procedure they may still not be able to participate in sports .
limb - salvage surgery had psychological and cosmetic advantages over amputation and might be the preferred treatment option in selected individual patients .
the huntington 's procedure is still a viable option for salvaging gap nonunions of the tibia .
the use of fibular grafts in the management of defects of long bones is a relatively straightforward procedure , requiring no microsurgical expertise .
this procedure is effective , but for optimal results the treatment needs to be individualized by the treating surgeon , with due consideration of soft tissue coverage , socioeconomic factors , and the available expertise .
Output:
| background : gap nonunion that may occur following trauma or infection is a challenging problem to treat . the patients with intact or united fibula , preserved sensation in the sole , and adequate vascularity , were managed by tibialization ( medialization ) of the fibula ( huntington 's procedure ) , to restore continuity of the tibia .
the goal of this retrospective analysis study is to report the mid - term results following the huntington 's procedure.materials and methods:22 patients ( 20 males and two females ) age 16 - 34 years with segmental tibial loss more than 6 cm were operated for tibialization of fibula .
the procedure was two - staged in seven and single - staged in the rest 15 patients , where the lateral aspect of the leg was relatively supple .
in the two - staged procedure , the distal tibiofibular synostosis was performed six - to - eight weeks after the proximal procedure .
weightbearing ( protected ) was started in a long leg cast after six - to - eight weeks of the second stage and continued for six - to - eight months , followed by the use of a brace.results:the fibula started showing signs of hypertrophy within the first year after the procedure and it was more than double in breath after the four - year period .
full and unprotected weightbearing on the operated leg was achieved at an average time of 16 months . at the final followup , ten patients were very satisfied , seven satisfied , and five fairly satisfied .
one patient had persistent nonunion at the proximal synostotic site even after bone grafting and secondary fixation.conclusion:huntington's procedure is a safe and simple salvage procedure and remains an excellent option for treating difficult infected nonunion of the tibia in the selected indications . |
PubmedSumm118631 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: king and mills performed the first trancathetar atrial septal defect ( asd ) closure in 1974 . since then , a large number of transcatheter asd closures have been done worldwide using various devices with different designs , advantages , and disadvantages . in many centers , this method of therapy
introduced recently with some new features , the occlutech figulla flex septal occluder ( offso , occlutech ) is similar in design to the amplatzer septal occluder ( aso , st .
several reports of its use in adults have been published . however , excluding the halabi and hijazi report on the first cases of the closure of two asds in an 8-year - old female child , there are very few reports in children . to the best of our knowledge ,
this is the largest series of successful transcatheter asd closure using the offso in children 12 years old in two pediatric interventional cardiovascular centers .
the aim of this retrospective review was to investigate the immediate and short - term results of transcatheter asd closure using the offso in children 12 years of age .
between january 2012 and november 2012 , 45 consecutive children 12 years old ( 25 females and 20 males ) underwent transcatheter asd closure using the offso in two centers , namely children s medical center and pediatric division of rajaie cardiovascular , medical and research center .
the children were between 2.5 and 12 years of age and weighed between 7.5 and 37 kg .
indications for intervention were right atrial and right ventricular enlargement in addition to calculated pulmonary blood flow to systemic blood flow ( qp / qs ) ratio > 1.5 and the absence of any associated congenital heart disease necessitating surgery .
standard right heart catheterization and pulmonary angiography in anteroposterior ( ap ) view with levophase angiograms were conducted in all the cases to definitely exclude anomalous pulmonary venous return .
transcatheter asd closure was performed under transthoracic echocardiography guidance and general anesthesia , according to the techniques already described . in all but one patient
, proper placement of the device was achieved via the conventional technique . in the latter case ,
the patients received intravenous heparin ( 80 units / kg ) , and intravenous cefazolin ( 50 mg / kg ) was administered during the procedure and continued for 24 hours after the procedure .
twenty - four to 48 hours after the procedure , the patients were discharged on 3 - 5 mg / kg of aspirin per day for 6 months . for the large offso s which covered almost all the length of the atrial septum , 12 months of aspirin administration was recommended . to determine how large the asd was in comparison with the patient s size , we measured the device diameter to the cardiac diameter ratio ( dd / cd ratio ) in anteroposterior projection after device release ( figure 1 ) .
the device diameter to the cardiac diameter index ( dd / cd index ) was calculated by dividing the dd / cd ratio by the body surface area
. the ratios of the device size to the patient s weight and to the defect size were also calculated .
descriptive analysis was performed to calculate mean standard deviation ( sd ) , median , and range of the continuous variables .
statistical analysis was performed using spss software version 18 ( spss inc . , chicago il , usa ) .
descriptive analysis was performed to calculate mean standard deviation ( sd ) , median , and range of the continuous variables .
information on the demographic , echocardiographic , and device parameters is provided in table 1 .
we had one cobra formation of the left disc in a 5-year - old patient , leading to the implantation of another offso ( figure 2 ) .
the device/ defect ratio was 1.17 in this case . on the day after the procedure
, transthoracic echocardiography showed no residual shunt and no impingement on the neighboring structures in all the patients .
no degree of atrioventricular block was observed in our patients after 24 hours and at 3 months follow - up .
there was exacerbation of previous headache in 2 cases , which could not be definitely attributed to device closure .
pulmonary artery pressure was normal in all the patients , with the exception of 2 , who had pulmonary hypertension .
we compared delivery sheath sizes between four available devices : offso ( occlutech gmbh , germany ) ; amplatzer ( st .
jude medical , usa ) ; cera ( lifetech scientific co. , ltd , china ) ; and cardi - o - fix asd occluder ( starway medical technology , inc . ,
the offso delivery sheaths were one to three french larger than the smallest available sheath for a similar device size of other brands .
we report successful transcatheter asd closure in 45 children 12 years old using the offso . to the best of our knowledge ,
reported late embolization of the figullar asd occluder in a 41-year - old female patient .
aaron et al . reported 4 cases of cobra formation in a 42 case series using the offso and suggested that cobra deformity is more common ( 0.1% ) with the offso than with the aso .
we had one case of cobra head deformity in our 45 patients ( 0.02% ) .
it may be posited that the ball - cage shape of the delivery system of the offso may allow excessive and undue twisting of the discs during the advancement through the long delivery sheath . however , since this complication happened in only one case in our series , we can not make any definite inference on it . careful evaluation of the cobra figure in the aaron et al .
study and in our cases shows that the twisting started from the waist and then extended a few millimeters above it .
aaron and his colleagues managed to prevent the re - occurrence of this phenomenon in their 3 other cases by releasing both discs in the left atrium .
this also confirms that the main culprit lies in the twisting of the wires in the waist segment of the device .
bearing that in mind as well as considering the manufacturer s tip , it may be postulated that strengthening the nitinol wires in the waist of the device may prevent or reduce this complication .
we also introduced the new index of dd / cd , which may be used as an adjunctive parameter to judge the size of an asd .
reported transcatheter asd closure using the offso in 74 consecutive adult patients with a 91.9% success rate and reported atrial arrhythmia in 2 of their patients : in one it disappeared spontaneously and in the other , it was treated with antiarrhythmic drugs .
the higher rates of complications and failures in their study may be attributed to the fact that they dealt with larger asds ( mean sd for device / defect ratio of 1.1 0.05 in their study vs. 0.840.77 in ours ) with a more complex case mix .
interestingly , the authors reported no single case of cobra head deformity . in comparison with the aso ,
it has no left atrial hub , so the risk of clot formation in the left atrium is much less and its tip is less traumatic .
it has the ability of 45-degree tilt of the delivery sheath ; accordingly , the device shape before release is much more similar to its final shape .
the screw mechanism of other devices has been replaced by a lock system which is easier to use and safer .
more importantly , no case of erosion after the offso implantation has been reported so far .
nevertheless , one may argue that this finding can be partly explained by its less frequent use and lower age ( 16 years ) since its invention in comparison to the aso ( 5 years ) .
the offso device sizes range from 6 to 40 mm ( 15 sizes ) , while the same spectrum of the defect size can be covered by 25 sizes of the aso .
another advantage is that the appropriate size of the delivery sheath for each device is already written on the outer box .
this is a simple , but important , point that increases the user - friendliness of this device .
although the offso has less implanted material , its nitinol wires are more than 20 times thicker than the nitinol wires used in the aso ( 0.082 to 0.186 vs. 0.004 to 0.0075 inch ) .
therefore , the offso needs larger venous delivery sheaths in comparison to the other similar devices .
this is not a problem in adults but may limit its use in small children .
the first pediatric implantation was reported by halabi and hijazi with excellent results in an 8-year - old girl .
pac et al . compared the offso and the aso in 75 patients at a mean age of 22.2 15.8 years .
the authors used the offso in 33 and the aso in 42 of their cases and concluded that the lower price of the offso is its advantage , but difficulty in selecting the correct device size in larger defects and the need for larger venous sheaths are two disadvantages of this device .
to the best of our knowledge , the present study is the largest series of the offso implantation in children to date .
we showed that the offso is safe for use in children , despite the need for relatively larger delivery sheaths .
the introduction of the second generation of this device ( figulla flex ii ) eliminates this potential fear as it will need smaller delivery sheaths .
this study was limited by a relatively large amount of missing information about the type of delivery sheaths .
this study was limited by a relatively large amount of missing information about the type of delivery sheaths the complication rate of transcatheter asd closure is less than 1% .
there were 45 patients recruited in the present study ; consequently , the absence of complications may be explained by the relatively low number of the patients enrolled in this study .
all information , such as the size of the delivery sheaths , was not available for all the patients .
although this device needs relatively larger delivery sheaths , its use can be safe while closing even large defects in children .
Output:
| backgrounddespite several reports regarding the use of the occlutech figulla flex septal occluder ( offso ) in adults , there are few reports on its use in children .
we sought to study the result of the transcatheter closure of atrial septal defect ( asd ) using the offso in children 12 years.methodswe enrolled 45 consecutive patients , ranging from 2.5 to 12 years of age , in two large pediatric cardiovascular centers .
all the children underwent complete echocardiographic examination before the procedure .
defect / device ratio and device / weight ratio were measured .
the device diameter to the cardiac diameter ratio ( dd / cd ratio ) in anteroposterior projection after device release and the dd / cd index were calculated by dividing the dd / cd ratio by the body surface area.resultsof the 45 enrolled patients , 25 ( 55% ) were female .
the range and mean standard deviation ( sd ) of age were 2.5 to 12 years and 6.8 2.5 years , respectively .
the range and mean sd weight were 8.5 to 37.0 kg and 19.7 7.2 kg , respectively .
successful implantation was performed in all the patients .
no major complications occurred in any of the subjects .
we encountered one cobra head deformity in one patient .
neither residual shunt nor conduction abnormality was observed in any of the cases.conclusiontranscatheter asd closure using the offso was effective in our pediatric patients .
although this device needs relatively larger delivery sheaths , its use is safe while closing even large defects in children . |
PubmedSumm118632 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: a trauma - scoring system converts the severity of injury into a number ( 1 ) .
scoring systems have been continuously developed to predict outcomes in patients with severe illness , improve resource allocation , and assist in clinical decision - making ( 2 - 4 ) . moreover ,
the ability to predict the outcome of trauma ( i.e. , mortality ) is perhaps the most fundamental use of injury severity scoring , which arises from the patients and their families ' desires to know the prognosis ( 5 ) . in recent years
, several trauma scoring systems have been developed and validated for use in prediction of outcome , quality assurance and research ( 6 ) .
more than 50 scoring systems have been published for the classification of trauma patients in the field , emergency room , and intensive care settings , so far ( 5 ) .
there are three main groups of scoring systems for risk prediction in trauma patients . anatomical scores , which provide an overall score based on grades of multiple injuries ; physiological scores are calculated by evaluating the physiological variables of the patient without considering the anatomical injuries ; and comorbidity scores that assess both anatomical injury variables and physiological parameters to increase the predictive power ( 5 , 7 )
. trauma injury severity score ( triss ) , the most widely used combined system , provided improvements in the ability to predict outcome after trauma ( 1 ) .
triss method had its inception in 1981 , followed by further consolidation of the concept with the major trauma outcome study .
this method provided improvements in the ability to predict trauma outcome , especially mortality , and therefore acquired worldwide popularity despite its limitations being recognized later ( 1 ) . the need to collect information on patients in the intensive care units ( icu ) and use that information to improve outcomes , led to the development of acute physiology , age , and chronic health evaluation system , known by its acronym apache ( 8) . in 1991 apache iii
was introduced , which consisted of a set of equations for predicting hospital mortality , icu mortality , hospital length of stay , icu length of stay , risk of active treatment , duration of mechanical ventilation , and therapeutic intervention scoring system ( tiss ) ( 8) .
practitioners do not widely accept apache iii , partly because it is proprietary and expensive .
in addition , its accuracy needs to be validated in trauma patients ( 1 ) .
therefore , the aim of this research was to assess the ability of triss and apache iii in predicting mortality rate of multiple trauma patients .
study design and setting
this prospective cross - sectional study included 152 multiple trauma patients admitted to the icu of imam hossein and hafte - tir hospitals , tehran , iran , in 2011 and 2012 .
patients younger than 14 years old and those who died within less than 4 hours of arrival in icu were excluded .
each patient s demographic data , vital signs ( systolic blood pressure ( sbp ) , heart rate , respiratory rate ( rr ) ) , mechanism of injury , level of consciousness ( based on glasgow coma scale ( gcs ) ) , and other required variables for calculation of triss and apache iii scores were recorded .
triss combines physiologic ( revised trauma score : rts ) and anatomic ( injury severity score : iss ) components of injury with age ( 9 ) .
data collected on admission to the emergency department , were used for calculation of rts and iss .
the protocol of this study was approved by the ethical committee of shahid beheshti university of medical sciences .
comparison of alive and dead patients trauma severity based on iss , rts , triss and apache iii scores mean standard deviation ; apache : acute physiology and chronic health evaluation .
rts : rts is the sum of the coded value multiplied of gcs , sbp , and rr ( 6 ) .
it is calculated by the following formula ( 6 ) : rts = 0.9368 gcs + 0.7326 sbp + 0.2908 rr rts values range from 0 to 7.84 .
it correlates reasonably well with mortality probability , and is calculated by adding the square of each of the coded values of the three most severely injured body regions and has a range from 0 to 75 .
rts , iss , and patient age , were placed in a logistic transformation to yield a survival probability ( ps ) ranging from 0 to 1 and death probability ( pod ) is 1-ps .
apache : apache iii scores were calculated for each patient from data collected during the first 24 hours of icu admission .
the apache iii score consists of several parts including the primary reason for icu admission , age , sex , race , preexisting comorbidities , and location prior to icu admission ( 10 ) .
receiver operating characteristic ( roc ) curve for triss model receiver operating characteristic ( roc ) curve for apache iii model
statistical analysis
data were analyzed using spss 21 software .
continuous variables were expressed as mean standard deviation and categorical ones were expressed in frequencies and percentages .
the area under the roc curve for each scale was used to compare the accuracy of the studied models ( 11 ) .
chi square and fisher exact test were used to compare categorical measures and students t - test was used to compare means .
120 of them were male ( 78.94% ) and 32 ( 21.05% ) were female .
mean age was 37.09 14.60 years ( range : 16 - 70 years ) .
the most common cause of trauma was traffic accidents involving : pedestrian - car accidents ( 23.36% ) , car - car accidents ( 17.76% ) , motorcycle - car accidents ( 14.47% ) , car rollover ( 11.84% ) , pedestrian- motorcycle accidents ( 9.21% ) and motor rollover ( 2.06% ) .
the others were falling down ( 16.44% ) , assault ( 3.64% ) and hanging ( 1.31% ) . in the end ,
triss predicted death rates significantly correlated with observed death rates ( p < 0.0001 ) .
the mean age of dead patients was 37.21 14.07 years compared to 37.0314.96 years for those who survived ( p = 0.4 ) .
table 1 compares alive and dead patients trauma severity based on iss , rts , triss , and apache iii scores .
the area under roc curve was 0.806 ( 95% ci : 0.663 - 0.908 ) for triss and 0.797 ( 95% ci : 0.652 - 0.901 ) for apache iii ( figure 1 and 2 , p = 0.2 ) .
the best cut - off points for mortality prediction were 13.2 ( sensitivity = 76.52% ; specificity = 95.65% ) and 51 ( sensitivity = 73.91% ; specificity = 78.26% ) for triss and apache iii , respectively .
according to results of our study , both triss and apache iii scores accurately predict mortality of multiple trauma patients .
the area under roc curve for triss and apache iii were not significantly different ( p = 0.2 ) , which means they are equally accurate in this regard .
there are several scoring systems and prognostic models in general use for outcome prediction in hospitalized patients .
the rationale behind using these scales commonly , is to rate illness severity to yield comparison between patients ( 12 , 13 ) .
objective risk estimates are particularly important in the high - cost , emotional , and technologically demanding environments of icu . because of the high costs of icu , precise quality assurance and utilization management strategies are essential ( 10 ) .
outcome prediction systems have become key tools to evaluate the care quality and the icu performance .
triss and apache iii are two systems currently in common use for measuring the condition of icu patients ( 14 ) .
triss has been used in quality assurance programs for evaluating trauma care and identifying unexpected deaths ( 15 , 16 ) .
the basis for the development of apache is the hypothesis that the severity of acute diseases can be measured by quantifying the degree of abnormality from multiple physiologic variables ( 17 ) .
the development of apache iii was based on the association between acute changes in a patient s physiologic balance and short - term risk of death ( 10 ) .
apache iii is widely used to assess illness severity of patients admitted to icu and to compare risk - adjusted outcomes between icus .
age , level of consciousness , biochemical , physiological , and chronic health variables in the first 24 hours of icu admission are incorporated into the score ( 18 ) . in line with the findings of the present study , thanapaisal and saksaen declared the ability of triss system in predicting mortality in intensive care unit ( icu ) trauma patients
safavi and honarmand found that apache iii provides more information than apache ii regarding determining factors of trauma severity ( 19 ) .
found that the overall explanatory power of apache iii on the first day of icu treatment ( r= 041 and roc = 0.90 ) compares well to that of previous versions of apache ( 10 ) .
however , in contrast to our results , some showed that trauma score or iss did not predict survival ( 20 ) .
vassar et al . evaluated the ability of triss to predict mortality in 1,000 icu admitted trauma patients and reported that triss overestimates mortality in patients whose predicted risk ranges were high ( 21 ) . likewise , wong et al .
( 1996 ) found that triss was a poor predictor of hospital death risk among icu admitted trauma patients ( 22 ) .
it seems that , triss has several advantages over apache for application on trauma patients .
first , triss has a detailed description of severity and location of anatomic injury , but apache does not include an assessment of trauma mechanism or the specific anatomical injury .
second , apache assesses the most abnormal physiologic data in the first 24 hours and is highly dependent on the quality of care given to the patient .
the results of our study give us the support to use both combined scores for mortality prediction in critically ill trauma patients .
however , the simplicity of triss calculation makes it easier and more applicable than apache iii ( 23 , 24 ) .
based on the results of this study , both triss and apache models have the same accuracy in predicting mortality of trauma patients .
therefore , it seems that triss model would be more applicable in this regard because of its easier calculation , consideration of trauma characteristics , and independency of patient care quality .
all authors passed four criteria for authorship contribution based on recommendations of the international committee of medical journal editors .
Output:
| introduction : more than 50 scoring systems have been published for classification of trauma patients in the field , emergency room , and intensive care settings , so far . the present study aimed to compare the ability of trauma injury severity score ( triss ) and acute physiology and chronic health evaluation ( apache ) iii in predicting mortality of intensive care unit ( icu ) admitted trauma patients .
methods : this prospective cross - sectional study included icu admitted multiple trauma patients of imam hossein and hafte - tir hospitals , tehran , iran , during 2011 and 2012 .
demographic data , vital signs , mechanism of injury and required variables for calculating apache iii score and triss were recorded .
the accuracy of the two models in predicting mortality of trauma patients was compared using area under the roc curve .
results:152 multiple trauma patients with mean age of 37.09 14.60 years were studied ( 78.94% male ) .
48 ( 31.57% ) cases died . for both apache iii and triss , predicted death rates significantly correlated with observed death rates ( p < 0.0001 ) .
the mean age of dead patients was 37.21 14.07 years compared to 37.0314.96 years for those who survived ( p = 0.4 ) .
the area under roc curve was 0.806 ( 95% ci : 0.663 - 0.908 ) for triss and 0.797 ( 95% ci : 0.652 - 0.901 ) for apache iii ( p = 0.2 ) .
conclusion : based on the results of this study , both triss and apache models have the same accuracy in predicting mortality of icu admitted trauma patients .
therefore , it seems that triss model would be more applicable in this regard because of its easier calculation , consideration of trauma characteristics , and independency of patient care quality . |
PubmedSumm118633 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: temporal transcriptional control of gene expression is often achieved through the dynamic interactions of activator and repressor proteins with promoters .
one of the most common ways of switching between these two modes is through competition for promoter occupancy by mutually exclusive binding to the same dna site ( reviewed in thiel et al . , 2004 ) .
however , this mechanism is only generally applicable to proteins that share overlapping dna binding specificities and are usually from the same transcription factor family .
more elaborate mechanisms must be employed if no overlap in dna - binding site is possible , although little is known about such mechanisms .
cell cycle - dependent gene expression provides an excellent model to study temporal transcriptional control mechanisms .
indeed , among multiple regulatory mechanisms of cell - cycle progression , one of the most important control points is at the transcriptional level and leads to the expression of key regulators in a cyclical manner ( simon et al . , 2001 ; reviewed in wittenberg and reed , 2005 ) .
peaks of gene expression can be identified at various points in the cell cycle , but two important control points in saccharomyces cerevisiae are at the g2/m phase and m / g1 phase transitions ( reviewed in wittenberg and reed , 2005 ) . the mads box transcription factor mcm1p plays an important role in the transcriptional regulation of genes expressed at both of these control points . at g2/m phase ,
mcm1p controls the expression of a group of genes known as the clb2 cluster , which contains targets such as clb2 , cdc20 , and spo12 ( althoefer et al . , 1995 ) .
mcm1p forms a complex on clb2 gene cluster promoters with the forkhead transcription factor fkh2p ( koranda et al . ,
, 2000 ; pic et al . , 2000 ; zhu et al . , 2000 ; reviewed in breeden , 2000 ) and the coactivator ndd1p ( koranda et al .
this complex is regulated by cell cycle - dependent kinases that cooperate to give maximal activation through sequential phosphorylation of fkh2p and ndd1p ( darieva et al . , 2003 , 2006 ; reynolds et al . , 2003 ; pic - taylor et al . ,
mcm1p also forms higher - order complexes on early cell cycle box ( ecb ) elements at promoters of genes expressed at the m / g1 phase transition such as cln3 and mcm3 ( mai et al . ,
however , in contrast to the clb2 gene cluster , no positively acting partner protein(s ) has yet been found that cooperates with mcm1p to regulate these m / g1 phase genes .
more recently , the closely related homeodomain repressor proteins yox1p and yhp1p were shown to play a repressive role at ecb - containing promoters ( pramila et al .
yox1p and yhp1p interact directly with mcm1p as well as forming protein - dna contacts with a binding site adjacent to the mcm1p recognition element in the ecb ( pramila et al . ,
moreover , similar yox1p - binding sites can be found in the promoters of a subset of genes from the clb2 gene cluster such as cdc20 and spo12 .
importantly , loss of yox1p and yhp1p alters the precise timing of the expression of these genes in the cell cycle , but not of other genes in the clb2 gene cluster such as clb2 itself ( pramila et al . , 2002 ) .
this suggests that yox1p also plays a key role in controlling the timing of expression of a subset of clb2 cluster genes , restricting their expression to a later time point in the cell cycle than other genes of the clb2 gene cluster .
it is unclear whether similar control mechanisms operate in mammalian cells , but homeodomain proteins are known to interact with srf , the mammalian homolog of mcm1p ( grueneberg et al . , 1992 ;
moreover , forkhead proteins play an important role in cell - cycle control in mammals ( reviewed in laoukili et al .
, 2007 ; lam et al . , 2006 ) , and at least two of these , foxo3 and foxk1 , can directly affect srf function ( liu et al . , 2005 ; freddie et al . , 2007 )
thus , it is important to understand the relationships and functions of the interactions between forkhead , homeodomain , and mads box proteins . despite the importance of yox1p in the regulation of cell cycle - dependent gene expression ,
little is known about how it represses mcm1p transcription factor complexes . with regard to the mcm1p - fkh2p complex ,
a simple competition model between yox1p and the activator fkh2p for a common dna - binding site seemed unlikely , as the yox1p and fkh2p dna - binding sites are positioned on the opposite sides of the mcm1p - binding motif ( e.g. , see figure 1a ) . thus , to begin to understand the repressive process , we investigated the molecular mechanisms through which yox1p interacts with mcm1p .
unexpectedly , yox1p binding to mcm1p is mutually exclusive with fkh2p binding despite the spatial separation of their dna recognition elements .
our data therefore reveal an atypical mode of repression that involves competition between an activator protein and a repressor protein for interaction with a common combinatorial partner rather than for a common dna recognition element .
yox1p negatively regulates a number of genes whose expression peaks transiently during the m phase of the cell cycle , including mcm3 , which is usually expressed at the m / g1 border ( pramila et al . , 2002 ) .
however , yox1p also appears to be important for repressing genes that are expressed earlier in m phase such as spo12 .
the spo12 promoter contains a putative yox1p - binding site juxtaposed to a mcm1p - binding site ( figure 1a ) .
hence , to establish whether a yox1p - mcm1p complex forms on alternative promoters in addition to mcm3 and , if so , whether mcm1p and yox1p are sufficient for complex formation , we carried out an immobilized template - binding assay using a recombinant version of mcm1p ( mcm1p(198 ) ) , in vitro - translated full - length yox1p , and a fragment spanning the putative yox1p - binding element in the spo12 promoter .
mcm1p(198 ) spans the dna - binding domain and is sufficient for cell viability ( christ and tye , 1991 ) .
although binding of yox1p to the spo12 promoter was readily detectable in the presence of mcm1p , little binding of yox1p was seen when mcm1p was not added , or the dna was omitted from the reaction ( figure 1b ) . to map the region(s ) of yox1p required for complex formation with dna - bound mcm1p , we first carried out gel retardation analysis with a short region of yox1p centered on the dna - binding homeodomain region ( figure 1c ) .
yox1p(151274 ) bound weakly to the spo12 promoter in the absence of mcm1p , but cooperative strong binding was detected upon addition of mcm1p ( figure 1d , compare lanes 3 and 5 ) .
the identity of the yox1p - containing complexes was confirmed by the partial supershifts / loss of binding of flag - tagged yox1p , which is seen upon inclusion of an anti - flag antibody ( figure 1d , lanes 5 and 6 ) .
in contrast , addition of fkh2p to the binding reaction did not promote the formation of yox1p dna - bound complexes ( figure 1e ) .
further deletion analysis of yox1p demonstrated that the region preceding the homeodomain ( amino acids 151175 ) was critical for the formation of mcm1p - dependent ternary dna - bound complexes ( figure 1f , compare lanes 2 and 4 with lanes 6 and 8) .
importantly , deletion of this region of yox1p did not affect its intrinsic dna binding properties , as both yox1p(151274 ) and a protein lacking amino acids 151175 ( yox1p(176274 ) ) bound to the spo12 promoter with equivalent affinities when titrated at higher protein concentrations ( figure s1b available online ) .
thus , amino acids in the region immediately flanking the n terminus of the homeodomain of yox1p play a critical role in promoting ternary complex formation with mcm1p and the spo12 promoter .
several other yeast transcription factors use sequences in addition to their dna - binding domains to enhance the formation of complexes with mcm1p through direct protein - protein interactions ( boros et al . , 2003 ; mead et al . , 1996 ;
thus , one likely role for yox1p sequences that are located outside of the homeodomain and are involved in ternary complex formation is binding to mcm1p .
this was tested by in vitro pull - down assays using recombinant mbp - mcm1p fusion proteins and either in vitro - translated or recombinant forms of yox1p . both full - length yox1p and the truncated yox1p(151274 )
could form complexes with mcm1p ( figure s1c ) . however , further truncation of yox1p to remove amino acids 151175 , yox1p(176274 ) , resulted in a substantial loss of interaction with mcm1p ( figure 1 g ) .
importantly , the inclusion of ethidium bromide in the binding reaction did not stop this interaction , demonstrating that the binding was not mediated through interactions with contaminating nonspecific dna ( figure s1d ) .
hence , amino acids located in the immediate n - terminal flanking region of the homeodomain of yox1p are important for protein - protein interactions with mcm1p .
a putative yox1p - binding site flanks the mcm1p - binding site in the spo12 promoter ( figure 1a ; pramila et al . , 2002 ) . to probe the importance of this site for yox1p binding , a mutant form of the spo12 promoter
was analyzed that contained a disrupted yox1p - binding site ( figure 2a ) .
whereas yox1p - mcm1p complexes could readily be detected on the wild - type spo12 promoter , no yox1p - mcm1p complexes were detectable when the putative yox1p - binding site had been mutated ( figure 2b , compare lanes 3 and 8) .
in contrast , mcm1p binding was unaffected and fkh2p - mcm1p complexes could form with equal efficiency on either the wild - type or the mutant spo12 promoter ( figure 2b , compare lanes 1 and 5 with lanes 6 and 10 ) . to further assess the dna - binding site requirements for yox1p recruitment to dna , we moved the yox1p site away from the mcm1p site by either two or five nucleotides while keeping the sequence of the yox1p - binding motif intact .
the formation of yox1p - mcm1p complexes decreased upon insertion of two nucleotides between the yox1p- and mcm1p - binding sites and was further diminished upon insertion of five nucleotides ( figure 2c ) .
these data indicate that yox1p - dna interactions are essential for the formation of dna - bound yox1p - mcm1p complexes and that the correct spacing of the two binding sites is critically important for efficient complex formation .
other proteins that interact with mcm1p to form ternary dna - bound complexes such as mat2 ( mead et al . , 1996 ; tan and richmond , 1998 ) and fkh2p ( boros et al . , 2003 ) use short peptide motifs for direct binding to mcm1p in which aromatic residues are the major interaction determinants .
there are three aromatic residues in the region between amino acids 151 and 174 in yox1p ( figure 3a ) , and hence we tested their importance for complex formation with mcm1p .
mbp pull - down assays with yox1p proteins mutated at either f153 , f155 , or f163 showed much - reduced interaction with mcm1p , indicating an important role for these individual phe residues ( figure 3b ) . furthermore ,
the ability of these mutant versions of yox1p to form complexes with mcm1p on the spo12 promoter was severely reduced ( figure 3c , lanes 710 ) , although their autonomous dna binding ability was unaffected ( figure 3c , lanes 25 ) .
moreover , titration experiments with recombinant yox1p proteins confirmed the reduced ternary complex forming ability of the yox1p mutant proteins on an alternative binding site derived from the mcm3 promoter ( figure s2b ) .
collectively , these results demonstrate that aromatic residues in the region preceding the homeodomain of yox1p play critical roles in complex formation with mcm1p .
yox1p was originally identified based on the premise that it was the most related yeast protein to human phox1 , which interacts with the mads box protein srf ( pramila et al . , 2002 ) .
complex formation between phox1 and srf is thought to be driven by the homeodomain ( grueneberg et al . , 1992 ) , and single amino acid mutations , such as e114h ,
were shown to disrupt functional interactions between phox1 and srf on reporter genes ( simon et al . , 1997 ) .
however , phox1 shows little homology with yox1p in the region immediately n terminal to the homeodomain , which was mapped as important for yox1p binding to mcm1p .
to probe whether the homeodomain might also be involved in the yox1p - mcm1p interaction , we introduced an amino acid substitution ( e196h ) into the equivalent position in the homeodomain of yox1p . however , this mutant protein was still able to efficiently form complexes with mcm1p both in solution ( figure s2e ) and on dna ( figure s2f ) .
in contrast , the mutant protein yox1p(n226q ) , which was predicted to be unable to bind dna based on similarities to phox1 ( grueneberg et al . , 1992 ) , was unable to form ternary complexes with mcm1p on dna ( figure s3d ) , although it could still bind to mcm1p in solution ( figure s2d ) .
thus , the mechanisms used by phox1 and yox1p to bind to mads box proteins differ substantially , with phox1 primarily using the homeodomain whereas yox1p uses a unique region preceding the homeodomain .
to establish whether the interactions that we detect in vitro are important for the in vivo function of yox1p , we examined the effect of introducing wild - type ( wt ) yox1p and yox1p(f155a ) , expressed under the control of its own promoter , from the ycplac22 vector into a yox1yhp1 double - mutant strain .
the expression levels of both forms of yox1p were identical ( figure 4a ) , and the overall cell - cycle profiles were similar for both strains when released from factor arrest ( figure s3a ) .
however , differences were detected in the levels of expression of several potential yox1p - mcm1p - regulated genes .
the expression of the g2-m phase - expressed genes spo12 and cdc20 and the m - g1 phase - expressed gene mcm3 are severely perturbed , with both earlier onset ( 28 versus 42 min for spo12 ) and higher levels of expression being detected in the strain expressing yox1p(f155a ) ( figure 4b ) . these genes all contain potential yox1p - binding sites in their promoters . in contrast , the expression of the late g1 phase - expressed gene cln2 and the g2-m phase - expressed gene clb2 , which do not contain yox1p - binding sites in their promoters , were not derepressed and displayed more similar timing of cyclical expression in cells expressing yox1p(f155a ) compared with those expressing wild - type yox1p ( figure 4b ) .
the premature and higher than normal expression of a subset of g2-m and m - g1 phase - expressed genes in the presence of yox1p(f155a ) is similar to the effects seen when both yox1 and yhp1 are deleted ( figure s3b ; pramila et al . ,
this effect is consistent with a loss - of - function mutation of yox1p , although additional residual activities of yox1p(f155a ) appear likely due to the extended activation in comparison to complete loss of yox1p . to establish whether the effects of the f155a mutation on spo12 and mcm3 gene expression were due to lack of promoter binding by yox1p(f155a ) ,
as expected , cyclical binding of wild - type yox1p could be detected on the spo12 and mcm3 promoters , with the timing of reduction of yox1p binding in g2-m phases corresponding to the timing of increased expression of spo12 and mcm3 ( compare figures 4b and 4c ) .
however , promoter binding was largely abolished in strains expressing yox1p(f155a ) ( figure 4c ) .
collectively , these data therefore establish that mutation of the mcm1p - interacting region of yox1p reduces its recruitment to promoters and thereby compromises temporal yox1p - mediated repression of promoter activity .
mcm1p contains a hydrophobic pocket found on the surface of the mads dna - binding domain ( tan and richmond , 1998 ) , and mutation of this pocket on mcm1p by the introduction of a v69e mutation disrupts interactions with fkh2p ( boros et al . , 2003 ) .
to establish whether the same pocket on mcm1p is involved in binding yox1p , we first tested protein - protein interactions between yox1p and the v69e mutant form of mcm1p . in comparison to wild - type mcm1p(wt ) , mcm1p(v69e ) exhibited reduced interactions with both yox1p and fkh2p ( figure s4a ) .
furthermore , the formation of dna - bound ternary complexes containing mcm1p and either yox1p or fkh2p was severely attenuated in the presence of mcm1p(v69e ) ( figure s4b ) .
however , interactions between yox1p and the surface of the mads dna - binding domain are likely to be subtly different than those mediated by fkh2p , as only fkh2p can form detectable interactions with the mammalian protein srf , albeit weakly ( figure s4c ) .
together , these results demonstrate that both yox1p and fkh2p bind to a region centered on a hydrophobic pocket on the surface of the mads box dna - binding domain of mcm1p .
as both yox1p and fkh2p bind to a region centered on the same hydrophobic pocket on mcm1p , this raised the possibility that they bind in a mutually exclusive manner to mcm1p .
we therefore tested this by titrating increasing amounts of yox1p into binding reactions containing mcm1p and fkh2p proteins . indeed , increasing concentrations of yox1p caused a loss of fkh2p - mcm1p ternary complex formation , involving both full - length fkh2p(1862 ) and the truncated fkh2p(1458 ) version , with concomitant formation of an mcm1p - yox1p complex ( figures 5b , s4e , and s4f ) . similarly , increasing amounts of full - length fkh2p could outcompete yox1p binding to mcm1p on the spo12 promoter in a dose - dependent manner ( figure 5c ) , and fkh2p(1458 ) could block yox1p binding ( figure s4f , lanes 8 and 9 ) .
this finding is surprising as mcm1p is dimeric , and in theory , both fkh2p and yox1p would be expected to bind simultaneously ; however , there was no sign of a higher - order complex containing fkh2p , yox1p , and mcm1p , even when recombinant proteins were used to eliminate the nonspecific bands on the gel ( figure s4f ) . to rule out potential effects transmitted through the dna
, we performed gel retardation experiments in the presence of the isolated forkhead dna - binding domain of fkh2p ( fkh2p(325458 ) ) ( figure s4f ) .
this truncated protein is unable to cooperatively form complexes with mcm1p ( boros et al . ,
in contrast to the results seen with longer forms of fkh2p , fkh2p(325458 ) did not compete with yox1p for mcm1p binding but instead was able to form a higher - order complex containing fkh2p , yox1p , and mcm1p ( figure 5d , lanes 35 ) .
thus , interaction of fkh2p with mcm1p appears essential to establish competitive binding . to further establish a role for protein - protein interactions in establishing the competitive binding mechanism
, we analyzed the effects of mutant proteins and dna - binding elements on the competition phenomenon .
we therefore tested yox1p(f155a ) for its ability to displace fkh2p from fkh2p - mcm1p complexes . in comparison to wild - type yox1p , yox1p(f155a ) showed much - reduced ability to compete with fkh2p for mcm1p binding ( figure 6a , lanes 17 ) , even though its intrinsic dna binding ability is unperturbed ( figure 3c ) .
moreover , wild - type yox1p was unable to compete efficiently with fkh2p for complex formation with mcm1p when the yox1p - binding site on the spo12 promoter was mutated ( figure 6a , lanes 811 ) , demonstrating that dna binding , in addition to protein - protein interactions , is required for effective competition .
furthermore , when the spacing of the yox1p- and mcm1p - binding sites is increased , competition with fkh2p for binding to mcm1p is diminished ( figure s5 ) .
this point was further underlined by the observation that a dna - binding incompetent form of yox1p ( yox1p(n226q ) ) was unable to compete with fkh2p for binding to mcm1p on the wild - type spo12 promoter fragment ( figure 6b ) .
together , these results demonstrate that the formation of dna - bound complexes between mcm1p and either yox1p or fkh2p is a mutually exclusive event .
moreover , we establish that both protein - protein and protein - dna interactions by yox1p are essential to enable the protein to compete with fkh2p for complex formation with mcm1p .
as fkh2p is an activator protein that cyclically associates with its target promoters ( voth et al . , 2007 ) and yox1p is a repressor protein that displays cyclical stability and association with target promoters ( pramila et al . , 2002 ) , it was possible that competition between yox1p and fkh2p for interaction with mcm1p could explain how yox1p can repress the expression of a subset of fkh2p target genes that contain yox1p - binding sites .
we therefore tested this hypothesis by first examining the occupancy of wild - type and mutant versions of the promoter of the yox1p / fkh2p target gene spo12 in vivo . to rule out indirect effects of potentially perturbing the cell cycle by affecting endogenous spo12 expression , we integrated a plasmid containing a fusion of the spo12 promoter linked to the e. coli lacz gene .
strains harboring the wild - type promoter and a mutant version with a disrupted yox1p - binding site ( figure 2a ) were created , and the effect on promoter activity was determined by measuring -galactosidase activity . as expected , the activity of the mutant promoter was increased through loss of binding of the yox1p repressor ( figure 7a ) .
as a control , we determined the occupancy of the endogenous clb2 promoter , which was unchanged irrespective of the status of the spo12 promoter fusion ( figures 7b and 7c ) .
in contrast , upon mutation of the yox1p site , occupancy by either fkh2p ( figure 7b ) or ndd1p ( figure 7c ) on the spo12 promoter fusion rose substantially .
next , we examined the effect of overexpression of either wild - type yox1p or yox1p(f155a ) that is defective in mcm1p binding and fkh2p displacement activity in vitro . in this case , we used ndd1p as a readout to indicate that correctly formed fkh2p - mcm1p complexes were assembled on the promoter ( koranda et al . , 2000 ) .
induction of wild - type yox1p resulted in a decrease in ndd1p occupancy on the endogenous spo12 promoter , which contains a juxtaposed yox1p - binding site ( figure 7d ) .
however , overexpression of yox1p(f155a ) was unable to efficiently displace ndd1p binding from the spo12 promoter .
importantly , both wild - type and mutant forms of yox1p were expressed to similar levels ( figure s6 ) . as a final test of our model
, we performed re - chip analysis to examine whether co - occupancy of the spo12 promoter by fkh2p and yox1p could be detected .
however , whereas mcm1p binding to the spo12 promoter could be detected in both fkh2p- and yox1p - precipitated material , little binding of fkh2p was detectable when yox1p was used in the first chip , and conversely , little binding of yox1p was detectable when fkh2p was used in the first chip ( figure 7e ) . as expected , only fkh2p - mcm1p or yox1p - mcm1p co - occupancy was detected at the clb2 and mcm3 promoters , respectively ( figure 7e ) .
thus , the absence of detectable complexes containing both fkh2p and yox1p on the spo12 promoter in vivo is fully consistent with our model in which yox1p and fkh2p compete for interaction with promoter - bound mcm1p .
recent studies in s. cerevisiae indicate that , rather than two major waves of gene expression at g1/s and g2/m phases , there are many overlapping waves of expression with subtly different timing mechanisms , each with their associated transcriptional regulatory circuitry .
although a limited number of regulators have been identified , it is becoming increasingly apparent that these can be combined in different ways to provide unique control opportunities to individual or subsets of promoters , determining precise timings of cell cycle - dependent gene expression ( horak et al .
, we have uncovered an atypical mechanism of antagonism between transcriptional activators and repressors during m phase of the cell cycle .
mcm1p acts as a common platform for recruitment of the homeodomain repressor protein yox1p and the forkhead transcription activator protein fkh2p .
these interactions with mcm1p are mutually exclusive , and hence , the timing of recruitment of these two regulators to promoters during the cell cycle determines the transcriptional status of cyclically regulated target genes .
interactions between yox1p and mcm1p are driven via a combination of protein - dna interactions involving the homeodomain of yox1p and through direct protein - protein interactions with the mads box dna - binding domain of mcm1p .
though we have only tested the dna - binding domain of mcm1p in vitro , it is likely that the interactions are relevant to full - length mcm1p as we validate our results in vivo wherein full - length mcm1p is present .
several aromatic residues that are clustered on a short peptide in the flanking region located n terminal to the homeodomain of yox1p were found to be important for these interactions .
many other yeast and mammalian transcription factors use short peptides that are distinct from their dna - binding domains to bind to mads box proteins ( mead et al . , 1996 ; tan and richmond , 1998 ; hassler and richmond , 2001 ; shore and sharrocks , 1994 ) .
a common feature is the use of aromatic residues to drive the protein - protein interactions with the mads box partner proteins .
indeed , the structures of the mat2-mcm1p and sap-1-srf complexes both reveal that hydrophobic residues insert into a common hydrophobic pocket found on the surface of the mads dna - binding domain ( tan and richmond , 1998 ; hassler and richmond , 2001 ) .
furthermore , molecular studies have implicated the same hydrophobic pocket as a major determinant of fkh2p - mcm1p interactions , most likely through insertion of an aromatic residue from fkh2p , as there are three important aromatic residues in fkh2p required for interaction with mcm1p ( boros et al . , 2003 ) . in mammalian systems
, the coactivator mal also uses aromatic residues to interact with the hydrophobic pocket on srf ( zaromytidou et al . , 2006 ) .
thus , a common mode of interaction between mads box proteins and their interaction partners has been adopted by a heterologous array of binding partners . however , despite these similarities , there are key differences in how some proteins interact with mads box proteins .
this is exemplified by the closest human homologs of fkh2p and yox1p , foxk1 and phox1 , respectively .
foxk1 interactions with srf are driven by the forkhead dna - binding domain rather than a flanking peptide ( freddie et al . , 2007 ) ,
and interactions between phox1 and srf appear to be directed by the homeodomain ( grueneberg et al . , 1992 ) , although direct biochemical proof of the latter is lacking .
similarly , the homeodomain of nkx-2.5 is sufficient for binding to srf ( chen and schwartz , 1996 ) .
however , it is striking that , in yeast , flanking dna - binding sites for fkh2p and yox1p can be found in close juxtaposition to mcm1p dna - binding sites , whereas in mammals , there does not appear to be such combinatorial sites .
this suggests that the role of the dna - binding domain of mads box - interacting proteins has been subverted through evolution from primarily mediating protein - dna contacts in yeast to providing protein - protein interactions in higher organisms .
the direct competition for mcm1p binding by yox1p and fkh2p was unexpected due to the clear separation of their dna - binding sites on opposite sides of the mcm1p dna - binding site ( figure 7f ) .
however , each protein contacts a region centered on the same binding pocket of mcm1p , and as interaction with mcm1p is essential for the recruitment of both fkh2p ( boros et al .
, 2003 ; hollenhorst et al . , 2001 ) and yox1p , only one protein can be recruited at a time .
mcm1p is a dimer and , as such , can theoretically present two identical surfaces that could accommodate two interacting proteins .
however , as this clearly does not occur , it suggests that these proteins lack the flexibility to interact with both surfaces of mcm1p , and that the structure of the dna - bound complex adds constraints , which means that only one of these proteins is allowed to bind to one ( the same ) surface of mcm1p at any given time .
alternatively , it is possible that protein binding to mcm1p straddles both sides of mcm1p , preventing proper access to the second binding surface .
indeed , it is possible that fkh2p binds as a dimer with only one subunit contacting dna , as fkh2p dimerization has been reported previously ( hollenhorst et al . ,
, a similar scenario has been observed in mammalian systems in which the activator proteins mal and elk-1 compete for binding to the same surface of the dimeric mads box protein srf , despite both apparently functioning as monomers ( zaromytidou et al . , 2006 ) .
it was previously suggested that yox1p might function to displace the coactivator protein ndd1p ( pramila et al . , 2002 ) .
here , we show that this does occur but through an indirect mechanism by displacing fkh2p and , hence , concomitant loss of ndd1p binding ( figures 7b7f ) . at the transcriptional level , this yox1p - dependent inhibition of formation of mcm1p - fkh2p - ndd1p complexes would result in a delay in the timing of activation of the clb2 cluster genes containing the yox1p - binding site compared to those that do not , which is exactly what is seen ( figure 4 ; pramila et al .
previous work has suggested that cell cycle - dependent gene expression of yox1 determines the timing of repression of yox1p target promoters ( pramila et al . , 2002 ) .
in this model , fluctuating yox1p protein levels would change its availability for promoter binding and repression . furthermore ,
relatively low constitutive expression of yox1 represses the cyclical expression of the yox1p target gene mcm3 ( pramila et al . , 2002 ) .
thus , the timing of fkh2p binding would be determined by the levels of yox1p present in the cell . in agreement with this model
, we find that constitutive expression of yox1 inhibited ndd1p binding to the yox1p - regulated spo12 promoter ( figure 7d ) .
however , it is also possible that additional mechanisms contribute to the regulation of yox1p / fkh2p competition for mcm1p binding .
( ubersax et al . , 2003 ) , and it is possible that this triggers changes in promoter occupancy and/or the proteolytic degradation and turnover of yox1p . although we have established the mechanism underlying the timing of expression of a subset of clb2 cluster genes in the cell cycle by yox1p , it remains unclear how yox1p regulates the timing of expression of ecb - controlled genes .
no other common juxtaposed binding motifs are obvious in the promoter regions of ecb genes , and no other binding partners for mcm1p that regulate ecb genes have been identified .
however , it is tempting to speculate that the mechanism of action is similar to the regulation of mcm1p - fkh2p and involves the displacement of an as yet unidentified coactivator that competes with yox1p for binding to the surface of the mcm1p mads box dna - binding domain ( figure 7f ) . notwithstanding
this possibility , in both scenarios , yox1p might also actively repress transcription through the recruitment of corepressor proteins that act , for example , on the local chromatin environment .
in addition to its activator role via ndd1p , fkh2p also has a repressive role and recruits the rpd3 corepressor to the clb2 promoter at early points in the cell cycle ( veis et al .
however , yox1p is unlikely to influence this activity , as the point of yox1p function is later in the cycle during m phase .
it is unclear why such an elaborate system for repression is utilized by yox1p , rather than a more typically found simple steric hindrance model whereby the activator and repressor proteins compete for the same site on dna .
dna binding sequence constraints probably dictate that this is not possible , as the recognition motifs for fkh2p and yox1p are quite different .
thus , by creating a system whereby promoter recruitment is dependent on cooperative interactions with a common binding partner , transcription factors from heterologous families are able to compete for promoter occupancy . furthermore , by invoking a third protein ( in this case mcm1p ) , the repressive activity of yox1p on fkh2p function can be made more specific and restricted to a subset of target genes on which mcm1p is also present and leave other genes on which fkh2p acts independently from mcm1p ( hollenhorst et al . , 2001 )
are also found in higher eukaryotes , some aspects of the combinatorial regulation mechanisms documented here are likely to be conserved . for example , the mads box protein srf interacts with the forkhead proteins foxk1 ( freddie et al . , 2007 ) and foxo4 ( liu et al . , 2005 ) and the homeodomain proteins phox1 ( grueneberg et al . , 1992 ) and nkx-2.5 ( chen and schwartz , 1996 ) . in these examples ,
interactions with forkhead proteins are repressive , whereas the homeodomain proteins work in a positive manner . however , the direct interplay involving interactions between these proteins has not been investigated . in a more general context ,
the phenomenon of sequence - specific repressor and activator proteins antagonizing each other through competing for the same protein surface on a common dna - bound transcription factor is likely to be more widespread in timing mechanisms in other transcriptional control networks .
thus , these studies may have important implications for understanding the mechanisms by which gene expression determines the precise timing of events in cellular processes , in addition to cell proliferation , such as development .
wild - type and truncated derivatives of yox1p and fkh2p were produced by coupled in vitro transcription and translation ( using rabbit reticulocyte lysates , promega ) and subsequently analyzed and quantified by phosphorimaging .
his - tagged mcm1p(198 ) , yox1p , and fkh2p derivatives were expressed in escherichia coli bl21(de3 ) and purified using nickel - nta - agarose resin ( qiagen ) according to standard procedures .
for the experiments in figure s4b , the mcm1p moiety was released from the fusion protein while still attached to the beads by cleavage with factor xa .
protein concentrations were estimated compared to bsa standards . for titration experiments , a 9- , 10- , or 25-fold concentration range was used , with typical amounts of protein ranging from 50 to 500 ng .
when two different proteins were directly compared , protein levels were normalized by comparison on the same gel .
mbp pull - down assays with in vitro - translated and recombinant proteins were carried out as described previously for gst pull - down assays ( shore and sharrocks , 1994 ) . where indicated , ethidium bromide ( 100 g / ml ) was added to the mbp - fusion protein immobilized on the beads prior to the addition of yox1p proteins and was included in all wash buffers .
to detect epitope - tagged derivatives by western analysis , anti - flag ( sigma ) and anti - myc ( 9e10 ; santa cruz ) antibodies and supersignal west dura substrate ( pierce ) were used .
gel retardation and immobilized template binding assays were performed as described previously ( boros et al . ,
complexes containing flag - tagged yox1p derivatives were detected by including , 2.5 g of anti - flag antibody ( sigma ) in the binding reaction .
his - tagged mcm1p(198 ) was used in all gel retardation experiments apart from those in figure s4b in which mcm1p(196 ) cleaved from mbp - mcm1p(196 ) derivatives was used . immobilized template binding assays were performed in the same buffers as used in gel retardation assays .
14 ng of biotin - labeled dna - binding sites were incubated with 7 l magnetic streptavidin beads ( dynal ) for 15 min with gentle shaking .
the beads were subsequently washed in 100 l binding buffer , and recombinant mcm1p(198 ) was then added and allowed to bind for 15 min with gentle shaking
. the beads were washed , and then s - labeled in vitro - translated yox1p was added and allowed to bind for 1 hr . after washing the beads twice in binding buffer , the proteins were eluted on ice for 15 min in elution buffer ( 1 pbs , 1 m nacl ) and then analyzed by 12% sds page followed by fixing , drying , and visualization by phosphorimaging .
gal1-promoter - driven constructs were induced , and transformations were performed as described previously ( darieva et al . , 2003 ) .
yeast cultures were synchronized in g1 phase by treatment with -factor ( 5 g / ml ) for 3 hr .
dna content analyses were performed using propidium iodide - stained cells as described previously ( darieva et al . , 2006 ) .
rna extraction and real - time rt - pcr analysis were carried out as described previously ( darieva et al . ,
2006 ) using the following primer pairs : ads1444/1445 ( cln2 ) , ads1436/1437 ( clb2 ) , ads1704/1705 ( spo12 ) , ads1926/1927 ( cdc20 ) , ads1708/1709 ( mcm3 ) , and ads1439/1440 ( act1 ) .
details of chromatin immunoprecipitation ( chip ) and re - chip assays are provided in the supplemental information .
Output:
| summarytranscriptional control is exerted by the antagonistic activities of activator and repressor proteins . in saccharomyces
cerevisiae , transcription factor complexes containing the mads box protein mcm1p are key regulators of cell cycle - dependent transcription at both the g2/m and m / g1 transitions .
the homeodomain repressor protein yox1p acts in a complex with mcm1p to control the timing of gene expression . here
, we show that yox1p interacts with mcm1p through a motif located n terminally to its homeodomain .
yox1p functions as a transcriptional repressor by competing with the forkhead transcription activator protein fkh2p for binding to mcm1p through protein - protein interactions at promoters of a subset of mcm1p - regulated genes .
importantly , this competition is not through binding the same dna site that is commonly observed .
thus , this study describes a different mechanism for determining the timing of cell cycle - dependent gene expression that involves competition between short peptide motifs in repressor and activator proteins for interaction with a common binding partner . |
PubmedSumm118634 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: ovarian hyperstimulation syndrome ( ohss ) is a serious often life - threatening , iatrogenic complication of assisted reproduction .
moderate to severe ohss has been reported to occur in 0.22% of all ovarian stimulation cycles .
the syndrome is characterized by an acute shift of protein - rich fluid from the vascular compartment into the third space leading to hemoconcentration , decreased renal perfusion , oliguria , thrombo - embolism , eventually renal shut down , and death in the most extreme cases .
ohss has been classified as early - occurring 35 days after the human chorionic gonadotrophin ( hcg ) trigger and late - occurring 57 days after embryo transfer .
mediators implicated in the development of the syndrome include vascular endothelial growth factor ( vegf ) , interleukins ( il1 , il2 , il6 , il8 , endothelin 1 , and tumor necrosis factor -alpha ) , prostaglandins , and renin angiotensin aldosterone system .
vegf is currently considered to be the most important mediator as it increases vascular permeability leading to the fluid shift which is responsible for the symptomatology of ohss , that is , abdominal distension , respiratory distress , oliguria , and thromboembolic phenomenon .
hcg is used to trigger final oocyte maturation in ovarian stimulation because of its similarity to luteinizing hormone ( lh ) and its long half - life .
hcg causes the stimulated enlarged ovaries to produce the angiogenic molecule vegf . since , the advent of gonadotropin - releasing hormone ( gnrh ) antagonist protocols in in vitro fertilization ( ivf ) it has become possible to use gnrh agonist as an ovulation trigger .
gnrh agonist trigger is effective in mounting an adequate lh surge for final oocyte maturation additionally it reduces the risk of ohss .
use of the agonist trigger with elective cryopreservation of all embryos - the segmentation approach - has been promoted as a way to have an ohss free clinic .
units having a good vitrification program have adopted this approach . unfortunately , despite the great benefit of this approach a few cases have been reported in the literature recently where ohss developed despite the use of the segmental approach .
we report a case of severe early ohss despite the use of segmentation approach and ohss prophylaxis , to highlight the importance of vigilance and early intervention .
a 33-year - old patient with polycystic ovary syndrome ( pcos ) presented at our clinic with primary infertility for 9 years , in june 2014 .
her menstrual cycles had been irregular since menarche , and she was only menstruating after progesterone withdrawal since a few years .
husband 's semen analysis revealed oligoasthenoteratozoospermia ( count 5 million / ml , motility 25% , and 1% normal morphology ) .
she had previously undergone 2 cycles of intrauterine insemination and one cycle of controlled ovarian stimulation ( cos ) for ivf . during this cycle patient had been down - regulated with gnrh agonist and cos was started with 150 iu of recombinant follicle stimulating hormone ( rfsh ) .
cycle was canceled due to lack of ovarian response after 8 days of stimulation . on examination ,
her hormonal profile showed an fsh of 4 miu / ml , lh - 7.4 miu / ml , e2 - 46.3 pg / ml , and antimullerian hormone ( amh ) - 27 ng / ml . her blood sugar , liver function tests , serum creatinine , and lipid profile was normal .
baseline scan showed large pco ovaries with > 20 antral follicles per ovary , a typical cobweb appearance .
the right ovarian measured 47 mm 26 mm 37 mm , volume 25 cc , and the left ovary measured 48 mm 33 mm 36 mm with a volume of 30 cc .
she was advised ivf - intra - cytoplasmic sperm injection because of the presence of a male factor in addition to ovulatory dysfunction .
extensive counseling was done for ohss risk and agonist trigger , and elective freezing of all embryos was discussed as a strategy to avoid development of ohss .
the patient was stimulated under fixed day antagonist protocol with rfsh 200 iu s / c daily from the 2 day of her periods . dose of 200 iu was decided based on her last attempted ivf cycle and high bmi 29 kg / m .
baseline antral follicle sizes were between 4 and 8 mm , and e2 was 35 pg / ml . on day 6 of stimulation
, she had > 15 follicles 89 mm on both sides and e2 levels were 1030 pg / ml .
gnrh antagonist cetrorelix ( intas pharmaceuticals ) was started and stimulation continued with injection menopur 225 iu ( ferring pharmaceutical ) . on day 8 of stimulation
all follicles were below 1012 mm and hence the dose of gonadotropin was increased to 300 iu .
e2 levels taken on day 8 were 3100 pg / ml . after increasing the dose , follicular growth was appreciated .
two days later on day 10 , after 9 days of stimulation she had 6 follicles 16 mm average diameter , rest of the follicles more than 20 per ovary were in the range of 1214 mm .
the ovaries were large with the right ovary being > 8 cm and left > 10 cm .
some amount of pelvic free fluid had been appreciated since day 6 , and this had increased marginally on the day of the trigger . there was no free fluid in the flanks or upper abdomen .
the patient complained of pain in the lower abdomen and some nausea since day 8 of stimulation .
she received 1 mg leuprolide acetate ( sun pharmaceuticals ) for final oocyte maturation on stimulation day 10 .
the total dose of gonadotrophin received by the patient was 2050 iu . on the day of her trigger , e2 was 10,045 pg / ml and progesterone was 3.5 ng / ml . a total of 44 oocytes were retrieved with 37 mii oocytes of which 20 fertilized .
blood was collected for evaluation of hematocrit , liver enzymes , and creatinine . at egg collection fluid in the pelvis
was approximately 200300 cc , upper abdomen , and flanks were found to be fluid free .
following oocyte pick - up ( opu ) patient was kept prophylactically on dopamine agonist cabergolin ( 0.5 mg ) once a day , gnrh antagonist 0.25 mg s / c twice a day and enoxaparin 20 mg s / c daily .
she was admitted overnight for observation because of the large ovaries and abdominal discomfort she was experiencing .
twenty - four hours after opu patient complained of pain , nausea , and abdominal distention .
her vitals were stable , but urine output was < 30 ml / h ( 200 ml ) in last 24 h despite adequate hydration and administration of he s .
ultrasound showed bilateral enlarged ovaries occupying most of the pelvis and abdomen up to an inch above the umbilicus .
nonechogenic fluid was now visible mainly in the upper abdomen , the pelvis , and most of the abdomen being occupied by the ovaries .
100 ml of albumin was repeated after 4 h , and 500 ml of saline was also administered .
the patient was moved to the intensive care unit ( icu ) for further management . in icu patient
urinary output improved in the next 24 h , ascitic fluid showed a marginal increase beyond that seen at 36 h , bilateral pleural effusion was appreciated , and the liver enzymes were mildly altered .
creatinine and electrolyte levels were within range though sodium was borderline low . since , there was not much increase in ascites tapping
it is mostly iatrogenic and exposes a young disease free woman to a potentially lethal complication .
advances in reproductive medicine have led to improved protocols ( gnrh antagonist protocol ) and drugs ( cabergoline ) to minimize this risk .
the use of gnrh agonist trigger as an alternative to hcg came as an important breakthrough in ivf .
subsequently many trials in self - cycles and donor cycles showed the effectiveness of gnrh agonist trigger in ohss prevention , an incidence of 0% ohss was reported with agonist .
it has been suggested that the shorter duration of the agonist - induced lh surge leads to a significant reduction in the total amount of gonadotropins released .
supraphysiological steroid levels in cos with their negative impact on pituitary secretion of lh , coupled with the altered nature of the agonist - induced lh surge and the duration of lh receptor stimulation , has been proposed as a mechanism for the reduction of ohss witnessed with the agonist trigger .
the benefit of ohss prevention comes with a disadvantage of a reduced pregnancy rates ( pr ) when an agonist trigger is used .
this is a result of the letuolytic effect of the gnrh agonist combined with unfavorable endometrial changes .
administration of hcg even in small a dose of 1500 iu improves implantation but leaves the patient vulnerable to ohss .
2013 reported development of ohss in 22% patients on agonist flare when 1500 iu of hcg was added to improve pr .
this involved the use of an antagonist protocol with gnrh agonist trigger and elective cryopreservation of all embryos and subsequently embryo transfer in a natural or hormone replacement cycle .
this approach has been used with great success and seemed finally to provide an answer to this dreaded complication .
we report a case of severe early ohss in a pcos patient where not only was a segmentation approach used , but ohss prophylaxis was also initiated immediately after opu .
surprisingly she developed oliguria within 24 h of oocyte collection even though there was only a moderate amount of ascites and the hematocrit was just marginally raised .
oliguria , a late manifestation in ohss , exists in about 30% of cases , and renal failure secondary to hypoperfusion or to compressive obstruction occurs in about 1.4% of the severe forms of ohss .
early oliguria seen in our patient could be the result of a number of factors working in tandem to reduce renal perfusion .
, 2000 carried out a longitudinal study of women undergoing superovulation to obtain data about hematocrit and osmolality before the onset of clinical symptoms of ohss .
they reported that in ohss patient a significant increase in osmolality was observed , during the later stages of follicular growth , before hcg administration .
they also observed a loss of around 20% of blood volume between days 2 and 4 after administration of hcg .
these alterations in blood volume were not seen in patients with uncomplicated cycles ( p < 0.006 ) .
their observations suggest that alterations in osmoregulation and volume homeostasis occur much earlier than previously suspectedduring oocyte recovery hemorrhage occurs due to pricking of vessels on the ovarian surface and within the follicles aspirated . a large number of aspirated follicles could have caused enough hemorrhage to reduce the circulatory volume further .
the body compensatory mechanism would have prevented a drop in blood pressure and tachycardiaraised intra - abdominal pressure due to a combination of large ovaries and moderate ascites could have resulted in abdominal compartment syndrome and obstructive uropathy leading to oliguria .
, 2000 carried out a longitudinal study of women undergoing superovulation to obtain data about hematocrit and osmolality before the onset of clinical symptoms of ohss .
they reported that in ohss patient a significant increase in osmolality was observed , during the later stages of follicular growth , before hcg administration .
they also observed a loss of around 20% of blood volume between days 2 and 4 after administration of hcg .
these alterations in blood volume were not seen in patients with uncomplicated cycles ( p < 0.006 ) .
their observations suggest that alterations in osmoregulation and volume homeostasis occur much earlier than previously suspected during oocyte recovery hemorrhage occurs due to pricking of vessels on the ovarian surface and within the follicles aspirated .
a large number of aspirated follicles could have caused enough hemorrhage to reduce the circulatory volume further .
the body compensatory mechanism would have prevented a drop in blood pressure and tachycardia raised intra - abdominal pressure due to a combination of large ovaries and moderate ascites could have resulted in abdominal compartment syndrome and obstructive uropathy leading to oliguria .
cabergoline a dopaminergic agent blocks binding of vegf with vegf receptor thereby preventing an increase in vascular permeability .
it decreases the incidence and severity of the syndrome but can not prevent it completely , especially if there is hcg in circulation . vegf expression in granulosa cells
begins before hcg administration and is stimulated further by hcg exposure indicating thereby that the best time to start administration of dopaminergic agents is a few hours before giving the trigger .
starting cabergoline before trigger and giving it twice a day might have reduced the severity of ohss in our patient .
re - initiation of gnrh antagonist in the luteal phase to prevent severe early ohss was proposed by lainas et al .
the same author presented an observational cohort study in 2012 describing the outpatient management of severe early ohss with luteal antagonist administration .
it was demonstrated that luteal antagonist resulted in rapid resolution of severe ohss as early as 2 days after initiation , with a significant decline of ovarian volume , hematocrit , and ascites , as well as steroid concentrations , eliminating the need for albumin infusion and in - patient care . in a more recent study ,
we reinitiated antagonist from the day of oocyte retrieval hoping that it would initiate a quick leutolysis and decrease ovarian size .
having given an agonist trigger , we were not expecting the patient to go into ohss . within 24 h of opu
the patient developed oliguria and the ascitic fluid increased . unlike the cohort described by lainas et al .
2012 our patient required inpatient icu care . early detection and aggressive management helped to correct the hematocrit and blood biochemistry within 24 h. ascitic fluid starting reducing after 48 h and patient was comfortable without tapping .
this case underscores the importance of maintaining extreme care while stimulating pcos patients even when a segmentation approach is planned .
we should have started with a lower dose and made slower increments to avoid high levels of estradiol .
our patient also had a high amh though not as high as the case described by ling et al .
. it may be prudent to see if we can determine an association between amh levels and ovarian volume and the risk of ohss with agonist trigger , to identify this subgroup of patients .
the underlying cause of early ohss with segmentation approach is unclear , but the possibility that there may be an fsh and lh receptor mutation has been considered .
gonadotrophin receptor mutation may increase the patient 's sensitivity to fsh and lh / hcg .
2004 reported on familial recurrent spontaneous ohss in two families who had mutations of the fsh receptor , resulting in abnormal sensitivity to hcg .
genetic studies on vegf receptor may also reveal important information since it is important in the pathogenesis of ohss .
we believe our patient may be the carrier of such a mutation , and we are looking into the possibility of screening for this .
this case highlights the fact that an antagonist cycle with agonist trigger and freeze all policy in ivf does not necessarily eliminate ohss . even administering prophylaxis in the form of he
s , cabergoline , and antagonist post opu did not prevent the development of the syndrome .
clinicians must be vigilant to pick out patients at risk and exercise extreme care and caution during stimulation . starting with a smaller dose of fsh and avoiding
very high amh and a large ovarian volume may present a possibility of identifying women at risk , but the cut - off level needs to be determined .
Output:
| we report a case of early onset severe ovarian hyperstimulation syndrome ( ohss ) presenting with oliguria in an antagonist cycle triggered with gnrh agonist and a freeze - all approach .
prophylactic measures in the form of gnrh antagonist , cabergolin and plasma expanders were given after oocyte retrieval .
twenty - four hours after oocyte retrieval patient developed oliguria and moderate ascites .
she was managed in icu with albumin and diuretics .
she responded to conservative management and did not require paracentesis .
severe ohss can occur in pcos patients even after using a segmented approach i.e. gnrh agonist trigger with a freeze all policy .
patients at risk of ohss should be closely monitored following ovum pickup even when an agonist trigger has been given , for early detection and management . |
PubmedSumm118635 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: iron is crucial to humans biological functions and cellular biochemical processes 1,2 . both iron deficiency and iron overload pose significant and potentially fatal health risks , and the homeostasis of iron is tightly regulated .
when this regulation is disrupted , for example because of hereditary hemochromatosis , excessive absorption of iron by the intestine leads to cellular toxicity , tissue injury , and organ fibrosis .
such harmful effects are mediated through the deposition of iron in parenchymal cells of a number of vital organs , including the heart , pancreas , and liver .
iron - generated oxyradicals contribute toward the peroxidation of lipid membranes , leading to organelle fragility and cellular toxicity .
approximately one - third of the body s total iron is deposited in hepatocytes , sinusoidal mesenchymal cells , and reticuloendothelial cells 3,4 .
the liver also plays a fundamental role in recycling iron as the organ synthesizes both transferrin ( the main transporting protein ) and ferritin ( the major storage protein ) .
excessive iron deposition in the liver leads to further injuries by triggering hepatocellular necrosis 5 , inflammation 6 , fibrosis 7,8 , and even carcinoma 9 .
many experimental and clinical studies suggest that chronic iron deposition promotes the progression of liver damage and increases the risk of fibrosis , cirrhosis , and hepatocellular carcinoma in chronic hepatitis c patients 1013 . furthermore , some studies suggest that excess iron in the liver may induce adverse effects on patients response to antiviral therapy for chronic hepatitis c 14,15 .
data on iron metabolism and its clinical significance are relatively scarce in hepatitis b virus ( hbv)-related liver disease .
16 were the first to describe an association between changes in iron levels and hepatitis b infection in 1981 .
they reported that 33 patients who were persistent hbv carriers had significantly higher levels of serum iron than 34 patients who cleared the viral infection .
their data implied that high levels of serum iron may be related to the presence of chronic hbv infection .
however , they did not report serum ferritin or transferrin levels , or total iron - binding capacity 16 .
17 found elevated transferrin saturation and increased liver iron deposition in 27.1 and 48.7% , respectively , of hbv patients investigated .
18 reported elevated serum transferrin saturation and ferritin concentration in patients with hbv - related liver disease .
19 suggested that a successful treatment with lamivudine may correlate with reduction in serum ferritin levels in patients with chronic hepatitis and liver cirrhosis type b. conclusive data on the prevalence and clinical significance of disturbed iron metabolism in patients with hbv - related cirrhosis are still lacking .
especially , it remains unclear whether changed serum iron markers observed in hbv infection are related to hbv infection or to liver injury that is associated with chronic hbv infection . in this study , we determined the serum iron status of patients with hbv - related cirrhosis and investigated whether it is the direct hbv infection or hbv - related liver injury that leads to changes in serum iron markers .
the ethics committee of the first affiliated hospital of zhejiang university college of medicine approved all procedures , and the study was carried out according to the declaration of helsinki .
the chronic hepatitis b ( chb ) diagnosis was made in accordance with the criteria recommended by the viral hepatitis management guidelines , which were adopted by the chinese society of infectious diseases and parasitology , and the chinese society of hepatology , of the chinese medical association 20 in the 2000 xian conference .
briefly , chb is diagnosed when an hbv carrier experiences a clinical course of hepatitis b infection for more than 6 months , and may have shown symptoms or signs of hepatitis and abnormal hepatic function , or with histological changes .
patients with any of the following were excluded from the study : acute hepatitis ; hematologic disorders ; malignancies such as hepatocellular carcinoma ; pregnancy ; on - going steroid or pegylated interferon or nucleoside analog therapy ; homozygous or compound heterozygous hemochromatosis ( hfe ) gene mutations ; concurrence of hepatitis c virus , hepatitis d virus , hepatitis g virus , hiv infection , or autoimmune or other liver diseases ; alcohol abuse ( > 60 g / day ) or biochemical or histological features of alcoholic liver disease ; or large - volume blood transfusion ( > 6 u ) .
patients with chronic hbv infection ( n=156 ) who were referred to the clinic of liver diseases between july 2012 and december 2013 and fulfilled the above criteria were enrolled in this study .
eighty of the 156 patients were diagnosed with hbv - related cirrhosis and the remaining 76 patients were chronically hbv - infected , but noncirrhotic .
all patients received standard medical treatments including energy supplements , intravenous infusion of albumin and plasma , and preventive treatment of complications in accordance with the strategy for prevention and therapy of viral hepatitis reported in 2000 20 .
all the patients were positive for hepatitis b surface antigen ( hbsag ) for at least 6 months and all patients were positive for hbv dna .
a group of 58 healthy controls ( hcs ) were also included in the study that included healthcare staff with no known liver disease and no hbv infection .
each volunteer consumed less than 20 g / day of alcohol , and had normal iron indices and liver function tests at the time of evaluation .
the timing of blood collection for hcs was the same as that for patients . within 24 h after admission , after an overnight fast , blood samples were collected from all patients .
serum iron indices ( ferritin , iron , and transferrin ) were measured for each participant .
serum iron was tested using an automated roche analyzer system ( roche diagnostic , mannheim , germany ) .
serum ferritin was determined using an electrochemiluminescence assay ( abbott laboratories , chicago , illinois , usa ) and serum transferrin using an immunoturbidimetric method ( roche diagnostic ) .
serum albumin , total bilirubin , and alanine transaminase ( alt ) levels were measured using a hitachi 704 analyzer ( roche diagnostic ) . the alt upper limit of normal is 40
u / l . international normalized ratios ( inrs ) were measured using a sysmex ca1500 full - automatic analyzer ( sysmex corp , kobe , japan ) .
hbv serological markers ( hbsag and hbeag ) were assayed using commercial enzyme immunoassay kits ( abbott laboratories ) .
serum hbv dna levels were determined using a fluorescence quantitative pcr method ( pg , shenzhen , china ) .
patients with serum hbv dna greater than 500 iu / ml were referred to as hbv dna positive .
the diagnosis of cirrhosis was supported by liver biopsy in 40 patients ( 50% ) .
the diagnosis in the remaining 40 patients ( 50% ) was made on the basis of clinical ( e.g. physical stigmata of cirrhosis ) or biochemical manifestations ( decreased serum albumin and increased serum globulin ) , and imaging findings of ultrasonography or computed tomography ( nodular liver surface , coarsened echogenicity of liver parenchyma , enlarged spleen , or ascites ) . at the same time , 26 of 76 patients with noncirrhosis were diagnosed histologically and the remaining patients by clinical , endoscopic , or ultrasound evaluation .
baseline demographic and clinical characteristics were collected , including the model for end - stage liver disease ( meld ) score , in which higher scores reflect more severe liver disease .
cellular dna was extracted from peripheral blood leukocytes for pcr , cleaved by restriction enzymes rsai or bcli ( for c282y and h63d mutation analyses , respectively ) , and visualized by agarose gel migration ( state key laboratory , zhejiang university , china ) .
the severity of liver disease was evaluated by the meld score , which uses the patient s serum bilirubin and creatinine levels and the inr for prothrombin time to predict survival .
differences in variables were analyzed using analysis of variance and student s t - tests ( for normally distributed data ) or the kruskal
wallis and mann whitney u - tests ( for non - normally distributed data ) .
the -test or fisher s exact test was used for categorical data , as appropriate .
statistical analyses were performed using the statistical package spss version 12.0 ( spss inc . , chicago , illinois , usa ) , and the level of statistical significance was set at a p value less than 0.05 .
the ethics committee of the first affiliated hospital of zhejiang university college of medicine approved all procedures , and the study was carried out according to the declaration of helsinki .
the chronic hepatitis b ( chb ) diagnosis was made in accordance with the criteria recommended by the viral hepatitis management guidelines , which were adopted by the chinese society of infectious diseases and parasitology , and the chinese society of hepatology , of the chinese medical association 20 in the 2000 xian conference .
briefly , chb is diagnosed when an hbv carrier experiences a clinical course of hepatitis b infection for more than 6 months , and may have shown symptoms or signs of hepatitis and abnormal hepatic function , or with histological changes .
patients with any of the following were excluded from the study : acute hepatitis ; hematologic disorders ; malignancies such as hepatocellular carcinoma ; pregnancy ; on - going steroid or pegylated interferon or nucleoside analog therapy ; homozygous or compound heterozygous hemochromatosis ( hfe ) gene mutations ; concurrence of hepatitis c virus , hepatitis d virus , hepatitis g virus , hiv infection , or autoimmune or other liver diseases ; alcohol abuse ( > 60 g / day ) or biochemical or histological features of alcoholic liver disease ; or large - volume blood transfusion ( > 6 u ) .
patients with chronic hbv infection ( n=156 ) who were referred to the clinic of liver diseases between july 2012 and december 2013 and fulfilled the above criteria were enrolled in this study .
eighty of the 156 patients were diagnosed with hbv - related cirrhosis and the remaining 76 patients were chronically hbv - infected , but noncirrhotic .
all patients received standard medical treatments including energy supplements , intravenous infusion of albumin and plasma , and preventive treatment of complications in accordance with the strategy for prevention and therapy of viral hepatitis reported in 2000 20 .
all the patients were positive for hepatitis b surface antigen ( hbsag ) for at least 6 months and all patients were positive for hbv dna .
a group of 58 healthy controls ( hcs ) were also included in the study that included healthcare staff with no known liver disease and no hbv infection .
each volunteer consumed less than 20 g / day of alcohol , and had normal iron indices and liver function tests at the time of evaluation .
within 24 h after admission , after an overnight fast , blood samples were collected from all patients .
serum iron indices ( ferritin , iron , and transferrin ) were measured for each participant .
serum iron was tested using an automated roche analyzer system ( roche diagnostic , mannheim , germany ) .
serum ferritin was determined using an electrochemiluminescence assay ( abbott laboratories , chicago , illinois , usa ) and serum transferrin using an immunoturbidimetric method ( roche diagnostic ) .
serum albumin , total bilirubin , and alanine transaminase ( alt ) levels were measured using a hitachi 704 analyzer ( roche diagnostic ) .
were measured using a sysmex ca1500 full - automatic analyzer ( sysmex corp , kobe , japan ) .
hbv serological markers ( hbsag and hbeag ) were assayed using commercial enzyme immunoassay kits ( abbott laboratories ) .
serum hbv dna levels were determined using a fluorescence quantitative pcr method ( pg , shenzhen , china ) .
patients with serum hbv dna greater than 500 iu / ml were referred to as hbv dna positive .
the diagnosis of cirrhosis was supported by liver biopsy in 40 patients ( 50% ) .
the diagnosis in the remaining 40 patients ( 50% ) was made on the basis of clinical ( e.g. physical stigmata of cirrhosis ) or biochemical manifestations ( decreased serum albumin and increased serum globulin ) , and imaging findings of ultrasonography or computed tomography ( nodular liver surface , coarsened echogenicity of liver parenchyma , enlarged spleen , or ascites ) . at the same time , 26 of 76 patients with noncirrhosis were diagnosed histologically and the remaining patients by clinical , endoscopic , or ultrasound evaluation .
baseline demographic and clinical characteristics were collected , including the model for end - stage liver disease ( meld ) score , in which higher scores reflect more severe liver disease .
all patients were investigated for c282y and h63d mutations of hfe . cellular dna was extracted from peripheral blood leukocytes for pcr , cleaved by restriction enzymes rsai or bcli ( for c282y and h63d mutation analyses , respectively ) , and visualized by agarose gel migration ( state key laboratory , zhejiang university , china ) .
the severity of liver disease was evaluated by the meld score , which uses the patient s serum bilirubin and creatinine levels and the inr for prothrombin time to predict survival .
differences in variables were analyzed using analysis of variance and student s t - tests ( for normally distributed data ) or the kruskal
wallis and mann whitney u - tests ( for non - normally distributed data ) . the -test or fisher s exact test was used for categorical data , as appropriate .
statistical analyses were performed using the statistical package spss version 12.0 ( spss inc . , chicago , illinois , usa ) , and the level of statistical significance was set at a p value less than 0.05 .
a total of 156 chronic hbv - infected patients ( 80 cirrhotic and 76 noncirrhotic ) and 58 hcs were recruited into this study .
the study population ranged in age from 22 to 71 years , mean 46 years . compared with hcs and noncirrhotic
patients , patients with cirrhosis tended to be older men , more likely to have severe liver disease , lower levels of serum albumin , and higher inr , total bilirubin , alt , and meld scores .
clinical characteristics of the participants studied to exclude the possibility of skewed data for serum iron that could be because of sex , we first determined whether there was any difference in the serum iron levels between men and women .
no significant differences in serum iron levels were observed between men and women in the three groups .
specifically , in the hc group , the serum iron levels of men ( 9.622.15 mol / l , n=32 ) and women ( 9.652.16 mol / l , n=26 ) were similar ( p=0.361 ) . in the chb group ,
the serum iron levels of men ( 26.328.91 mol / l , n=50 ) and women ( 24.429.01 mol / l , n=26 ) were similar ( p=0.526 ) . in the cirrhosis group , the serum iron levels of men ( 29.7411.6 mol / l , n=68 ) and women ( 28.8210.43 mol / l , n=12 ) were similar ( p=0.392 ) .
the serum transferrin of the cirrhotic patients was significantly lower than that of the hcs and noncirrhotic patients ( p<0.001 , all ; table 2 ) .
serum iron concentrations and ferritin values of the cirrhotic patients were higher than those of the noncirrhotic patients and hcs ( p<0.001 , all ) . however , between the noncirrhotic patients and hcs , there was no significant difference in serum iron concentrations ( p=0.135 ) or ferritin values ( p=0.652 ) .
iron - associated parameters measured in cirrhotic and noncirrhotic hbv - infected patients and hcs to distinguish a potential link between iron markers and chronic hbv infection from that of iron markers and hbv - related liver injury , we first analyzed whether serum iron , ferritin , or transferrin levels were related to alt in hbv - infected patients ( fig .
1 ) . in cirrhotic patients , serum iron and ferritin levels correlated positively with serum alt levels ( serum iron : r=0.496 , p<0.001 ; ferritin : r=0.402 , p<0.001 ) . transferrin levels were inversely related to meld scores ( r=0.395 , p<0.001 ) , although there was no correlation between transferrin levels and alt ( r=0.084 , p=0.416 ) .
further analysis showed a negative association between transferrin and serum iron levels in these patients ( r=0.309 , p=0.007 ) . in noncirrhotic patients
, there was no correlation between serum iron and transferrin levels and alt levels , and transferrin showed no correlation with meld scores , but ferritin was correlated positively with serum alt ( r=0.353 , p<0.001 ; data not shown ) .
. serum concentrations of ( a ) iron , ( b ) ferritin , ( c ) transferrin , and ( d ) meld scores correlated with alt levels ; ( e ) correlation between iron and transferrin .
alt , alanine aminotransferase ; hbv , hepatitis b virus ; meld score , model for end - stage liver disease score .
we stratified cirrhotic patients by alt levels : low ( < 40 u / l ) and high ( 40
2 ) . compared with cirrhotic patients with low alt , those with high alt had significantly higher levels of serum iron ( p<0.001 ) , ferritin values ( p<0.001 ) , and meld scores ( p<0.035 ) . by contrast ,
the serum transferrin levels of the high - alt patients were significantly lower than those of the low - alt patients ( p<0.001 ) .
comparison of iron - associated parameters in cirrhotic patients according to low and high alt levels .
serum concentrations of ( a ) iron , ( b ) ferritin , ( c ) transferrin , and ( d ) meld scores in cirrhotic patients and compared with low ( < 40 u / l ) and high ( 40
alt , alanine aminotransferase ; meld score , model for end - stage liver disease score .
a total of 156 chronic hbv - infected patients ( 80 cirrhotic and 76 noncirrhotic ) and 58 hcs were recruited into this study .
the study population ranged in age from 22 to 71 years , mean 46 years . compared with hcs and noncirrhotic
patients , patients with cirrhosis tended to be older men , more likely to have severe liver disease , lower levels of serum albumin , and higher inr , total bilirubin , alt , and meld scores .
clinical characteristics of the participants studied to exclude the possibility of skewed data for serum iron that could be because of sex , we first determined whether there was any difference in the serum iron levels between men and women .
no significant differences in serum iron levels were observed between men and women in the three groups .
specifically , in the hc group , the serum iron levels of men ( 9.622.15 mol / l , n=32 ) and women ( 9.652.16 mol / l , n=26 ) were similar ( p=0.361 ) . in the chb group ,
the serum iron levels of men ( 26.328.91 mol / l , n=50 ) and women ( 24.429.01 mol / l , n=26 ) were similar ( p=0.526 ) . in the cirrhosis group , the serum iron levels of men ( 29.7411.6 mol / l , n=68 ) and women ( 28.8210.43 mol / l , n=12 ) were similar ( p=0.392 ) .
the serum transferrin of the cirrhotic patients was significantly lower than that of the hcs and noncirrhotic patients ( p<0.001 , all ; table 2 ) .
serum iron concentrations and ferritin values of the cirrhotic patients were higher than those of the noncirrhotic patients and hcs ( p<0.001 , all ) . however , between the noncirrhotic patients and hcs , there was no significant difference in serum iron concentrations ( p=0.135 ) or ferritin values ( p=0.652 ) .
to distinguish a potential link between iron markers and chronic hbv infection from that of iron markers and hbv - related liver injury , we first analyzed whether serum iron , ferritin , or transferrin levels were related to alt in hbv - infected patients ( fig .
1 ) . in cirrhotic patients , serum iron and ferritin levels correlated positively with serum alt levels ( serum iron : r=0.496 , p<0.001 ; ferritin : r=0.402 , p<0.001 ) . transferrin levels were inversely related to meld scores ( r=0.395 , p<0.001 ) , although there was no correlation between transferrin levels and alt ( r=0.084 , p=0.416 ) .
further analysis showed a negative association between transferrin and serum iron levels in these patients ( r=0.309 , p=0.007 ) .
in noncirrhotic patients , there was no correlation between serum iron and transferrin levels and alt levels , and transferrin showed no correlation with meld scores , but ferritin was correlated positively with serum alt ( r=0.353 , p<0.001 ; data not shown ) .
( b ) ferritin , ( c ) transferrin , and ( d ) meld scores correlated with alt levels ; ( e ) correlation between iron and transferrin .
alt , alanine aminotransferase ; hbv , hepatitis b virus ; meld score , model for end - stage liver disease score .
we stratified cirrhotic patients by alt levels : low ( < 40 u / l ) and high ( 40 u / l ; fig .
2 ) . compared with cirrhotic patients with low alt , those with high alt had significantly higher levels of serum iron ( p<0.001 ) , ferritin values ( p<0.001 ) , and meld scores ( p<0.035 ) . by contrast ,
the serum transferrin levels of the high - alt patients were significantly lower than those of the low - alt patients ( p<0.001 ) .
comparison of iron - associated parameters in cirrhotic patients according to low and high alt levels .
serum concentrations of ( a ) iron , ( b ) ferritin , ( c ) transferrin , and ( d ) meld scores in cirrhotic patients and compared with low ( < 40 u / l ) and high ( 40
alt , alanine aminotransferase ; meld score , model for end - stage liver disease score .
abnormal serum iron markers have been observed in chronic hbv infection 1619 , but earlier findings seemed to suggest that altered serum iron levels were associated with chronic hbv infection 16,17 .
chronic hbv infection may be or may not be accompanied by liver injury , whereas altered iron metabolism could be a reflection of pathological changes in the organs , such as the liver , involved in iron metabolism .
this raises the question of whether the altered iron level is associated with direct hbv infection or the related liver injury . in this study
, we determined the serum iron status of patients with chronic hbv , and investigated whether it is direct hbv infection or hbv - related liver injury that leads to changes in serum iron markers . in this study , our results showed that in hbv - related cirrhotic patients compared with noncirrhotic patients and the hcs , serum transferrin was significantly lower and serum iron was significantly higher .
we also observed a higher level of serum ferritin in cirrhotic patients , which is in agreement with the results of yonal et al .
. however , other authors did not observe alterations in serum iron levels 23 , or they reported a reduction , in liver cirrhosis and hepatocellular carcinoma patients 24 .
these discrepancies may be because of the differences in stages of liver diseases among the patients in the various studies .
our results address two unresolved issues in understanding abnormal iron metabolism in chronic hbv infection .
first , why were the changes in the serum iron markers observed in hbv cirrhotic patients ?
furthermore , is hbv infection or hbv - related liver injury more directly responsible for alterations in serum iron markers ?
our cirrhotic patients had on - going liver injury , as evidenced by elevated alt levels , whereas the noncirrhotic patients did not . by examining the associations between alt levels and serum iron markers in cirrhotic patients
however , there was no correlation between alt levels and serum iron and transferrin levels in noncirrhotic patients , suggesting the concurrence of liver injury and elevated serum iron and ferritin levels .
hepatic inflammation and dysfunction may interfere with iron metabolism ( including synthesis and clearance ) .
liver injury can result in the release of more ferritin into plasma and reduce the production of transferrin , leading to lower serum transferrin levels .
this in turn will reduce the transport of iron to the liver , erythrocytes , or both and increase serum iron .
the severity of liver dysfunction can be quantified by meld scores . in the present study ,
transferrin levels correlated negatively with the meld scores and serum iron levels of cirrhotic patients .
this supports our reasoning that it is liver injury that causes reduced serum transferrin levels .
furthermore , serum iron increased with meld scores . therefore , increased hepatic necroinflammatory activity accompanied by worsening liver function may be one explanation for aberrant serum iron parameters in cirrhotic patients .
our data clearly indicate that hbv - related liver injury , but not direct chronic hbv infection , is likely responsible for the changes in the serum iron markers .
indeed , several studies have shown that removing excess iron through therapeutic phlebotomy reduces the severity of hepatic inflammation associated with chronic hcv infection 10 .
in addition , bayraktar et al .
25 reported that desferrioxamine infusion to achieve a normal serum ferritin level increased the likelihood of a favorable response to interferon in patients with chronic hepatitis b. accordingly , routine monitoring of serum iron and other iron - associated parameters during clinical management of chronic hbv infection will be helpful in understanding alterations in iron metabolism in hbv and their influence on further liver injury .
elucidation of the association between abnormal serum iron and liver injury may suggest an additional therapeutic approach , such as iron - removal therapy , that could improve the overall efficacy and outcomes of current management of chronic hbv infection with liver injury .
our data only indicate , but not yet prove , the causal relationships between serum iron markers and liver injury in hbv - infected patients .
we do not have serum samples available for analysis of other biochemical markers such as aspartate aminotransferase and serum lactate dehydrogenase for liver injury and this was a single - center study ; the sample size was relatively small .
we found that in hbv - infected patients with cirrhosis , serum transferrin levels were lower and serum iron and ferritin were higher compared with both noncirrhotic hbv patients and hcs .
we conclude that the main cause of iron metabolism disorder in cirrhotic hbv - infected patients is liver injury , and most likely not chronic hbv infection directly .
we found that in hbv - infected patients with cirrhosis , serum transferrin levels were lower and serum iron and ferritin were higher compared with both noncirrhotic hbv patients and hcs .
we conclude that the main cause of iron metabolism disorder in cirrhotic hbv - infected patients is liver injury , and most likely not chronic hbv infection directly .
Output:
| objectivein patients with chronic hepatitis b virus ( hbv ) infection , it is not known whether altered serum iron markers are directly because of the infection or the associated liver injury . we determined the serum iron status of patients with chronic hbv infection , and investigated whether it is hbv infection or hbv - related liver injury that likely causes abnormal serum iron markers in chronic hbv infection.materials and methodsfor a retrospective study , chronic hbv - infected patients ( 80 patients with cirrhosis and 76 patients without cirrhosis ) and 58 healthy controls were enrolled .
serum alanine transaminase levels were measured to ascertain liver damage .
indicators of iron status included serum iron , ferritin , and transferrin.resultscompared with noncirrhotic patients and healthy controls , the serum transferrin of cirrhotic patients was lower and the serum iron and ferritin values were higher ( p<0.001 , all ) . in cirrhotic patients , the serum iron and ferritin levels correlated positively with serum alanine transaminase levels and the transferrin levels were inversely related to both end - stage liver disease scores and iron levels ( all p<0.01).conclusionserum iron markers tended to be aberrant in chronic hbv - infected patients with cirrhosis . the liver injury associated with hbv infection , but not chronic hbv infection directly , is likely the main cause for iron metabolism disorder . |
PubmedSumm118636 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: a complex assortment of regulatory systems is required for the embryogenesis and ontogeny , as well as for the maintenance , renewal , and repair , of the comprehensive array of organs and tissues which allow multicellular organisms like mammals to function and survive .
one of such critical regulatory systems is programmed cell death ( pcd ) [ 16 ] , best defined as being a sequence of events based on cellular metabolism that lead to cell destruction .
such a laconic definition of pcd includes nevertheless three distinct processes of cell death : apoptosis ( caspase - induced or caspase - independent ) , autophagic cell death ( caspase - induced or caspase - independent ) , and programmed necrosis ( caspase - induced or caspase - independent ) [ 1 , 2 , 710 ] .
the present paper will focus on specific aspects of the caspase - induced apoptosis side of pcd , particularly with regards to integrin - mediated signaling .
apoptosis is a finely tuned process that performs crucial roles in several embryogenetic and physiological processes , such as tissue development and homeostasis , as well as the removal of defective , damaged and/or obsolete cells [ 110 ] .
it is now well understood that regardless of their state of being , normal cells are intrinsically wired by default to enter apoptosis .
consequently , apoptosis must be kept in a suppressed mode when not needed and , therefore , cells require survival signals in order to remain alive [ 112 ] . depending on the cell type , the said signals will include those provided by specific growth factors and their receptors .
aside from the loss of survival signals , apoptosis can also be induced by selected proinflammatory cytokines , as well as through various insults such as those caused by free radicals , radiation , or dna - damaging agents , among others [ 110 ] . in typical instances of apoptosis ,
the death throes of a dying cell comprise membrane blebbing , chromatin condensation , dna degradation , organelle destruction , and cell shrinkage [ 110 ] . ultimately , the process results in the formation of apoptotic bodies that are either phagocytosed ( by macrophages or neighboring cells ) , or simply released into a lumen for subsequent evacuation [ 1 , 2 , 4 , 79 , 13 ] .
the bcl-2 ( b - cell chronic lymphocytic leukemia / lymphoma 2 ) family of proteins or homologs is well known to constitute a critical decisional center of cell survival and apoptosis [ 6 , 8 , 11 , 12 , 1417 ] .
some twenty members of this family have been identified so far in man [ 11 , 12 , 1417 ] .
while most bcl-2 homologs are ubiquitously expressed regardless of the cell type [ 6 , 8 , 11 , 12 , 1417 ] , some may be prominently , or even selectively , expressed in a more restricted subset of tissues [ 6 , 8 , 11 , 12 , 1417 ] .
a classic example of this is the p53-driven induction of the expression of the pro - apoptotics puma and noxa following dna damage , consequently forcing cells to undergo apoptosis [ 6 , 8 , 11 , 12 , 1417 ] .
bcl-2 homologs act primarily as apoptotic suppressors ( anti - apoptotics ; e.g. , bcl-2 , bcl - xl , mcl-1 ) , effectors ( pro - apoptotics ; namely , bax , bak , and bok ) , activators ( pro - apoptotics ; e.g. , bid / tbid , bim , puma ) , or sensitizers ( pro - apoptotics ; e.g. , bad , bmf , bik , noxa ) ( figure 1 ) [ 6 , 8 , 11 , 12 , 1417 ] . in general , the suppressors interact with the effectors in the cytosol to prevent effector translocation to mitochondria .
alternately , suppressors will bind effectors already present at mitochondrial membranes in order to prevent them from oligomerizing ( figure 1 ) [ 6 , 8 , 11 , 12 , 1417 ] . upon a given apoptotic stimulus
, the balance of anti- and pro - apoptotic homolog expression and activities will be affected so that the sensitizers and activators gain the upper hand , therefore allowing both groups to inhibit suppressors ( figure 1 ) [ 6 , 8 , 11 , 12 , 1417 ] .
additionally , activators will synergize with effectors to either help the latter translocate to mitochondria , or oligomerize with them at mitochondrial membranes ( figure 1 ) [ 6 , 8 , 11 , 12 , 1417 ] .
the end result is that effectors are now in force at mitochondrial membranes and are free to homo - oligomerize , or hetero - oligomerize , with activators or other effectors , in order to form pores ( figure 1 ) [ 6 , 8 , 11 , 12 , 1417 ] .
the consequent loss of mitochondrial membrane integrity leads to , among many things , the release of cytochrome c into the cytosol .
cytochrome c acts as a cofactor with apaf-1 ( apoptosis protease activating factor-1 ) in recruiting the precursor / inactive form of the initiator caspase casp-9 , thus forming the apoptosome and consequently resulting in the activation of casp-9 ( figure 1 ) [ 6 , 11 , 12 , 1418 ] . in turn
, casp-9 initiates an irreversible activation - amplification cascade of executioner caspases , such as casp-3 and casp-7 , which will cleave their many substrates ( e.g. , actin , kinases , lamins , and keratins ) .
moreover , executioner caspases will activate by cleavage other apoptotic executioners such as cad ( caspase - activated dnase ) , which enacts internucleosomal dna degradation ( figure 1 ) [ 11 , 12 , 1417 , 19 ] .
lastly , numerous additional molecules that are implicated in the decision ( or execution ) of apoptosis have been identified to date , including cytosolic iaps ( inhibitors of apoptosis ) which can inhibit caspases , as well as iap inhibitors ( e.g. , smac / diablo , omni ) which are released during the loss of mitochondrial membrane integrity ( figure 1 ) [ 6 , 8 , 11 , 12 , 1418 , 2023 ] .
thus , the fate of a cell depends principally on a tightly modulated balancing act between the anti- and pro - apoptotic activities from multiple bcl-2 homologs [ 6 , 8 , 11 , 12 , 1417 ] .
such a balance is established at its base through a modulation of the expression of various homologs according to the specific survival stimulus , cell type , and species concerned .
however , post - transcriptional and/or post - translational modulations ( e.g. , alternative splicing , phosphorylation , sequestration ) also contribute significantly to this balance [ 11 , 12 , 1417 , 2426 ] .
for instance , the phosphorylation of bad on either of the s112 , s136 , or s155 residues inactivates its sensitizer functions , whereas phosphorylation of at least two of these residues furthermore leads to its degradation by proteasome .
another example is the case of bid , which is normally expressed as an inactive precursor , and which consequently requires cleavage into its tbid form in order to enact its activator functions . also of note are bim and bmf , two homologs that are typically sequestered in microtubules and actin microfilaments , respectively , therefore requiring their liberation from such captivity in order to perform their pro - apoptotic functions [ 11 , 12 , 1417 , 2428 ] .
it is of note that the establishment of the apoptosome ( and consequent casp-9 activation ) constitutes what is generally recognized as the intrinsic , or
this mode is typically induced by pro - apoptotic stimuli such as the loss of survival signals or critical failures in the operation of cellular processes ( e.g. , high - error dna replication , plasma membrane peroxidation , dna damage , protein misfolding , mitochondrial dysfunction ) [ 112 , 17 , 18 ] .
however , there is another mode of induction of apoptosis known as the extrinsic ( or death receptor , receptor - mediated ) pathway .
this mode is induced by one type of pro - apoptotic stimulus , namely , the binding of death ligands
( e.g. , tumor necrosis factor ( tnf)- , fasl , or tnf - related apoptosis - inducing ligand / trail ) to specific death receptors .
once activated , these receptors lead to the recruitment of adaptor proteins such as fadd ( fas - associated death domain protein ) , which in turn recruit the precursor / inactive form of the initiator caspase casp-8 in order to form the disc ( death inducing signaling complex ) . consequently , this results in the activation of casp-8 [ 1012 , 17 , 2932 ] . in cells with a high density of death receptors and/or high expression of pro - casp-8 ,
the disc - induced activation of casp-8 will be of sufficient intensity to bring about a subsequent amplifying activation cascade of executioner caspases , therefore rendering the process irreversible .
however , in cells with a low density of death receptors and/or low expression of pro - casp-8 , the disc - induced activation of casp-8 will be instead of low intensity , in turn leading to low - intensity executioner caspase activation .
in this situation , casp-8 ( and/or executioner caspases ) will then have to ( a ) cleave bid into its activator - functional tbid form , ( b ) destabilize actin microfilaments and microtubules by cleavage to allow the release of bmf and bim , and/or ( c ) cleave microtubule - sequestered bim in order to directly release it .
these altogether lead to a subsequent shift in the balance of anti- and pro - apoptotic bcl-2 homolog activities , in effect causing a translocation of the death signal to mitochondria for the formation of the apoptosome and activation of casp-9and thus only then rendering the process irreversible [ 1012 , 1417 , 2932 ] .
similarly to growth factors and their receptors , cell - extracellular matrix ( ecm ) interactions play a major role in regulating the various known cellular processes , including the maintenance of cell survival [ 12 , 3338 ] .
the biological functions attributed to cell - ecm interactions are mediated primarily by integrin type transmembrane receptors [ 12 , 3339 ] .
so far , 18 subunits and 8 subunits have been identified in humans , with subunits noncovalently associating with subunits in order to form 24 distinct heterodimeric ( ) receptors with differing ligand specificities [ 3944 ] .
some and subunits can undergo post - transcriptional alternative splicing , or post - translational proteolytic processing , resulting largely in variants with alterations in their cytoplasmic tails in order to add further versatility to their roles and functions [ 3943 ] .
integrins can be divided into three main functional groups : cell - cell adhesion integrins , vascular integrins , and cell - ecm adhesion integrins .
it is those integrins that have the 1 subunit in common which constitute the majority of receptors for ecm components [ 3943 ] . also of this group
is the 64 integrin , which is expressed exclusively in epithelial cells [ 39 , 44 ] .
the repertoire of integrins ( and variants ) expressed by a given cell is dependent on the contexts of ecm composition , tissue - type , and species concerned [ 3344 ] .
taking into account that some ecm components may be bound by more than one integrin , it is therefore not surprising that integrin - mediated cellular responses to the ecm are quite varied and multifaceted [ 3944 ] . to this effect ,
the initial observations that a cell 's anchorage to its ecm constitutes a critical factor for its survival [ 45 , 46 ] were quickly followed by the realization that distinct ecm components and integrins are selectively implicated in the promotion of cell survival , depending on the tissue and species studied [ 3335 , 39 , 44 , 4749 ] . for instance , laminin-211 promotes the survival of human and mouse skeletal myocytes via the 7b1d integrin ( a laminin receptor ) , whereas laminin-511 and fibronectin fail to support myocyte survival [ 5053 ] . also in myocytes ,
laminin-211 upregulates the expression of bcl-2 and bcl - xl , promotes the s112 phosphorylation of bad , and downregulates the expression of bax and bak , whereas laminin-511 enacts the exact opposite effects .
additionally , laminin-111 can actually replace laminin-211 to promote the survival of mouse skeletal myocytes [ 5457 ] , but not human ones , and does so at least in part via the 7b1d integrin [ 54 , 57 ] .
the binding of an integrin to its ecm ligand produces not only a physical link with the cytoskeleton , but also generates a vast range of transduction signals which affect cell behavior , cell shape , and gene expression [ 12 , 33 , 34 , 36 , 43 , 4749 , 5861 ] .
it is now well established that a given repertoire of expressed integrins not only engenders distinct signals for a specific cell type , but also exerts a differential modulation of cellular processes within the same tissue [ 3344 , 47 , 48 , 5861 ] .
although well advanced , our understanding of the exact molecular bases of integrin - mediated signaling remains incomplete [ 5861 ] .
it is nevertheless known that an increasing number of pathways such as the phosphatidylinositol 3-kinase ( pi3-k)/akt pathway , the mek ( mitogen - activated protein kinase ( map ) kinase)/erk ( extracellular regulated kinase ) pathway , or the sapks ( stress - activated map kinases ) jnk ( c - jun n - terminal kinases ) and p38 , can be activated alone or in combination according to the repertoire of integrins expressed by a given cell [ 12 , 34 , 36 , 43 , 48 , 5862 ] . however , unlike most growth factor receptors , integrins are nonkinase receptors .
consequently , integrins require kinase proxies to enact signal transduction following their activation . to this effect , signaling by 1 integrins owes largely to the recruitment and activation of fak ( focal adhesion kinase ) at the cytoplasmic tail of the 1 subunit . in turn , fak typically recruits and activates src [ 12 , 33 , 34 , 36 , 48 , 5873 ] .
conversely , src may be the first to be recruited and activated at the cytoplasmic tails of subunits [ 62 , 71 , 74 ] and in turn recruit / activate fak [ 62 , 63 , 65 , 67 , 71 ] .
such integrin - mediated fak / src signaling allows for the downstream engagement of a plethora of pathways , largely due to the formation of diverse signaling cassettes through the recruitment by fak and/or src of an increasing array of signaling molecules
. these can include adaptors ( e.g. , sch , grb2 ) , scaffolders ( e.g. , irs-1insulin receptor substrate-1 ) , nucleotide exchangers ( e.g. , sos ) , small gtpases ( e.g. , ras ) , and other kinases ( e.g. , cas ) ( figure 2 ) [ 6273 , 75 ] .
similarly , integrin - mediated fak / src signaling contributes greatly in the assembly of focal adhesions via their interactions with a mounting number of partners ( e.g. , paxillin , talin , and vinculin ) , in order to not only create a bridge between the ecm and the actin cytoskeleton , but also to regulate the stability and organization of actin microfilaments [ 48 , 5865 , 69 , 71 , 75 , 76 ] .
this enables , or maintains , the sequestration of bmf and/or bim ( figure 2 ) .
the modulation of integrin - mediated signaling and focal adhesion assembly can also be generated via certain subunits ( e.g. , activation of src family members fyn or yes ) , via the association with membrane proteins ( e.g. , caveolin ) , or via other adaptors and kinases , such as ilk ( integrin - linked kinase ) ( figure 2 ) [ 34 , 39 , 43 , 48 , 5862 , 7678 ] .
incidentally , the epithelial 64 integrin likewise participates in the stimulation of pathways such as pi3-k / akt and/or mek / erk via its engagement of src ( but not fak ) and furthermore is a chief contributor in the formation of hemidesmosomes anchoring complexes which link physically the ecm to keratin intermediate filaments , thus further organizing / stabilizing the cytoskeleton of a cell [ 39 , 44 , 58 , 79 , 80 ] .
overall , signal transduction by integrins differs little from that of growth factor receptors with tyrosine kinase activity ( rtks ) .
it is therefore not surprising that there is much chatter between rtk- and integrin - mediated signaling , the two often cooperating in the regulation of various cell processes such as proliferation , migration , and survival [ 12 , 33 , 34 , 39 , 43 , 44 , 5873 , 77 , 7987 ] . to this effect
, integrins can enact inside - out activation of rtk signaling largely through their own engagement of fak , src and/or ilk [ 6273 , 7779 , 8287 ] .
reciprocity being the rule , rtks can perform inside - out activation of integrin signaling , mainly through their own engagement of src [ 6466 , 6971 , 86 , 87 ] .
therefore , the already wide range of integrin - mediated signals can be expanded vastly further through such cross - talk with various growth factor receptors .
the precise molecular mechanisms governing the promotion of cell survival by integrins remain to be fully elucidated .
nonetheless , pi3-k / akt and ras / raf / mek / erk constitute the best known cell survival - promoting pathways among the assorted ones identified so far as being engaged by integrin - mediated fak / src signaling [ 12 , 3336 , 47 , 5866 , 6870 , 72 , 73 , 80 , 81 , 88101 ] . with regards to the pi3-k / akt pathway
, akt is well known for its numerous cell survival functions such as the inhibitory phosphorylation of bax ( on the s184 residue ) , bad ( on s136 preferentially , but on s112 as well ) , and bim ( on s87 ) , as well as the phosphorylation of pro - casp-9 ( on s196 ) to suppress its activation and the inhibitory phosphorylation of gsk-3 ( glycogen synthase kinase-3 ; on s9 ) which , when active , positively phosphorylates bax ( on s163 ) and negatively phosphorylates mcl-1 ( on s155 , s159 and t163 ) ( figure 2 ) [ 11 , 12 , 1417 , 2426 , 34 , 81 , 8894 , 101 ] .
although ilk contributes in the formation of integrin - mediated focal adhesions by binding directly to the cytoplasmic tail of the subunits of activated receptors [ 7678 ] , it has also been shown to be pi3-k - dependent for its activation and capable of acting as an upstream contributor to the activation of akt [ 8284 , 88 , 89 , 91 ] . however , with the recent evidence that ilk is a pseudokinase [ 102 , 103 ] , its previously tacit kinase activation upon binding the cytoplasmic domain of integrin subunits , as well as its kinase signaling roles in promoting integrin - mediated cell survival , remain therefore contentious [ 8284 , 102 , 103 ] . at the very least ,
the scaffolding functions of ilk in focal adhesion assembly and actin microfilament linkage [ 7678 ] , as well as its implication in microtubule assembly , are likely to contribute in the sequestration of bmf and bim ( figure 2 ) .
similarly , the said scaffolding functions of ilk can be used by integrins to cross - talk with rtks , thus allowing for its contribution in rtk / integrin cooperative signaling in promoting cell survival [ 77 , 78 , 8286 ] . regarding the ras / raf / mek / erk pathway
, raf can phosphorylate bcl-2 ( on t69/s70 ) in order to potentialize its suppressor functions , whereas rsk-1 ( p90 ribosomal s6 kinase-1 ) , a usual effector of erk1/erk2 , enacts an inhibitory phosphorylation of bad ( on s112 ) ( figure 2 ) [ 11 , 12 , 1417 , 2426 , 81 , 9599 , 101 , 105107 ] .
additionally , erk1/erk2 themselves may phosphorylate bcl-2 ( presumably on t69/s70 ) to potentialize its suppressor functions , mcl-1 ( presumably on s159/t163 ) to protect it from degradation , bim ( on s69 and/or s87 ) to inhibit its activator functions and pro - casp-9 ( on t125 ) to prevent its activation ( figure 2 ) [ 11 , 12 , 1417 , 2426 , 81 , 9599 , 101 , 105 , 106 ] .
the pi3-k / akt and ras / raf / mek / erk pathways can furthermore cross - talk with each other in order to cooperatively promote cell survival .
for instance , ras can activate pi3-k , which in turn results in the activation of akt .
moreover , pdk1 ( phosphoinositide - dependent kinase-1 ) , another effector of pi3-k , can activate rsk-1 [ 88 , 94 , 106 , 107 ] . in any event , the engagement of pi3-k / akt and/or ras / raf / mek / erk results generally in an up - regulation of the expression of anti - apoptotic bcl-2 homologs and iaps , as well as a down - regulation of the expression of pro - apoptotic bcl-2 homologs ( figure 2 ) [ 11 , 12 , 1417 , 21 , 22 , 60 , 81 , 8899 ] .
additionally , the expression of c - flip ( cellular fadd - like il-1-converting enzyme - inhibitory protein ) , which blocks the formation of the disc by binding to fadd [ 12 , 30 , 32 , 81 ] , is likewise up - regulated [ 12 , 60 , 81 , 8899 ] .
hence , the importance of fak and/or src in the integrin - mediated promotion of cell survival is intimately linked with their pivotal role in the engagement of pathways such as pi3-k / akt and/or ras / raf / mek / erk ( figure 2 ) , depending on the composition of the signaling cassettes they help engender and the specific integrin receptors implicated , as well as according to the cell type and species studied [ 12 , 34 , 43 , 47 , 48 , 5873 , 80 ] .
interestingly , fak and src can also contribute directly in the promotion of cell survival , aside from their usual roles in the integrin - mediated assembly of focal adhesions and engagement of survival - promoting pathways ( figure 2 ) . indeed ,
src can phosphorylate pro - casp-8 ( on y380 ) to suppress its activation , whereas fak can bind rip1 ( receptor - interacting protein-1 ; a.k.a .
ripk1 ) in order to prevent its recruitment of fadd and consequent formation of the disc [ 109 , 110 ] .
all in all , it is therefore more than ever undisputable that a cell 's integrin - mediated anchorage to its ecm constitutes a powerful , multilayered , and complex device whose most significant purpose is to ensure survival . it should be noted here that the already complicated nature of the regulation of cell processes is strikingly enhanced by the implication of specific kinase isoforms and/or family kinase members , therefore often resulting in distinct or even differing
pi3-k isoforms complexes ( 4 catalytic subunit isoforms , 3 regulatory subunit isoforms ) , akt isoforms ( 1 to 3 ) , rsk isoforms ( 1 to 4 ) , irs isoforms ( 1 to 4 ) , or shc ( p46 , p52 , p66 ) and raf ( a- to c- ) family members , constitute but a few examples identified to date in humans [ 71 , 9496 , 98 , 101 , 105107 , 111113 ] .
that these can be selectively expressed depending on the tissue and species , in addition to the fact that they can perform specific functions even within the same given cell type , further emphasizes the reality of the vast intricacies that underlie the regulation of cell processes including of course cell survival , whether integrin mediated or otherwise .
considering the importance of integrin - mediated cell - ecm interactions in driving cell survival , it is therefore not surprising that the disruption , or loss , of integrin binding induces pcd namely , a form of caspase - dependent apoptosis that is termed anoikis ( a.k.a .
detachment - induced apoptosis or integrin - mediated death ) [ 10 , 12 , 3336 , 46 , 47 , 49 , 60 , 81 , 101 , 108 , 114120 ] . like apoptosis and pcd in general , anoikis performs important roles during organogenesis , as well as in tissue maintenance and renewal [ 3335 , 38 , 49 , 7981 , 101 , 117122 ] . for example
, the involution of mammary glands and the renewal of the epidermis , as well as that of the intestinal epithelium , implicate the induction of anoikis in obsolete cells [ 101 , 121126 ] . in this respect
, it is now recognized that cells are endowed with an innate / default anchorage - dependent surveillance system meant to ensure that all integrins expressed by them do interact with their respective ecm ligands , thus inducing anoikis when that is not the case . in other words , any cell that strays accidentally or otherwise from
its assigned position within its given tissue , either by interacting with a wrong ecm or by losing anchorage to its own ecm , is targeted for death [ 12 , 36 , 60 , 108 , 115 , 117 ] .
four - punch hit against cell survival that implicates elements from both the intrinsic and extrinsic pathways of caspase - dependent apoptosis .
comes from the deactivation of fak and/or src , leading to a disengagement of pathways such as pi3-k / akt and ras / raf / mek / erk ( figure 3 ) .
hence , the numerous pro - survival roles performed by these pathways ( figure 2 ) undergo failure .
the second punch comes from the concomitant disassembly of anchoring focal adhesions ( and/or hemidesmosomes ) , in large part by the loss of integrin - mediated engagement of fak , src , and/or ilk ( figure 2 ) , thus greatly destabilizing the cytoskeleton and consequently allowing the release of bmf and bim ( figure 3 ) .
additionally , the presence of p66 ( a member of the shc family of adaptor proteins ) at focal adhesions can induce an elevated / sustained activation of the small gtpase rhoa , which in turn contributes likewise in the destabilization of the cytoskeleton through effectors that remain to be fully identified .
interestingly , such anoikis - sensitizing function of p66 appears to be independent of its better known ability to translocate to mitochondria that is typically part of its apoptosis - inducing roles [ 113 , 127 ] .
the third punch consists in the activation of apoptotic kinases [ 12 , 36 , 81 , 101 , 108 , 115 , 117120 , 128 ] .
the roles of the sapks jnk and p38 in anoikis remain somewhat ambiguous [ 95 , 96 , 98 , 101 , 117 , 129134 ] . three isoforms for jnk ( 1 to 3 ) and four for p38 ( , , , and ) have been identified to date , all of which can be selectively expressed depending on the cell type and species studied [ 95 , 96 , 98 , 129134 ] .
accordingly , jnk and p38 will contribute to cell survival or apoptosis / anoikis , or neither , according to cell type as well as in an isoform - selective manner [ 95 , 96 , 98 , 129134 ] .
in addition , and again depending on the cell context as well as the specific stimulus , it will be either a jnk isoform , a p38 isoform , or an isoform of each , which will be implicated in cell survival or apoptosis / anoikis [ 95 , 96 , 98 , 101 , 129136 ] .
as example , jnk1 drives anoikis in canine kidney epithelial cells [ 128 , 137 , 138 ] , but not jnk2 [ 128 , 139 ] .
similarly , p38 is required for apoptosis / anoikis in rat cardiomyocytes and mouse skeletal myocytes , whereas p38 contributes in the promotion of survival in the former , while playing no role to this effect in the latter .
consequently , much remains to be understood of the implication of jnk and/or p38 in anoikis .
it is however generally accepted that a prolonged / sustained activation of specific jnk and/or p38 isoforms can allow them more than enough time to enact their deadlier functions , therefore driving the cell death process [ 95 , 96 , 98 , 101 , 115 , 118 , 128136 ] . to this effect , it is now well established that an elevated and/or sustained activation of an apoptotic jnk isoform , or p38 one , will result largely from the upstream activation of ask-1 ( apoptosis signal - regulating kinase-1 ) ( figure 3 ) [ 95 , 96 , 98 , 101 , 115 , 118 , 129136 , 141 , 142 ] . incidentally , akt phosphorylates ask-1 ( on s83 ) as part of its pro - survival functions , thus keeping the latter 's activation in check ( figures 2 - 3 ) [ 8893 , 141 , 142 ] .
little is known of the precise apoptotic roles , if any , that are enacted by each specific jnk and p38 isoforms [ 95 , 96 , 98 , 129136 ] .
nevertheless , it is recognized that apoptosis - induced jnk or p38 can generally perform numerous apoptotic - driving functions such as inducing / up - regulating the expression of fasl ( death ligand of fas ) for autocrine death stimulation , contributing in the destabilization of cytoskeletal elements ( such as microtubules and microfilaments ) to induce / enhance the liberation of bim and bmf , contributing to the membrane blebbing that is characteristic of apoptosis , down - regulating the expression of iaps and anti - apoptotic bcl-2 homologs while up - regulating that of pro - apoptotic ones , and phosphorylating homologs either in the cytosol or at mitochondria ( figure 3 ) [ 12 , 36 , 81 , 95 , 96 , 98 , 101 , 108 , 114 , 115 , 117120 , 129136 ] .
apoptotic phosphorylating functions have been mostly characterized so far in the case of jnk ( albeit not for any particular isoform ) , namely , the negative phosphorylation of bcl-2 ( on t69/s70/s87 ) , bcl - xl ( on s62 and/or t47/t115 ) , and mcl-1 ( on s121/t163 ) , the phosphorylation of bax ( t167 ) for its activation and mitochondrial translocation , the positive / potentiating phosphorylation of bad ( s128 ) , the phosphorylation of bid to produce an active jbid form ( instead of the usual tbid one ) , the phosphorylation of bim ( on t56 and either s44 or s58 ) to prevent its sequestration or cause its release from microtubules , and the phosphorylation of bmf ( s58 or s77 ) to prevent its sequestration , or cause its release from microfilaments ( figure 3 ) [ 11 , 12 , 1417 , 2428 , 128136 , 141 , 142 ] .
although similar apoptotic phosphorylations of bcl-2 homologs have been reported for p38 , the specific residues targeted are yet to be firmly identified ( figure 3 ) [ 11 , 12 , 1417 , 2428 , 129136 , 141 , 142 ] .
another apoptotic kinase family of note is the dapk family ( death associated protein kinase ; especially dapk1 ) [ 143146 ] .
although the exact mode of activation for dapk1 remains poorly understood , it has been observed that death receptor signaling ( namely , the receptors for tnf- and fasl ) can lead to dapk1 activation [ 143148 ] .
incidentally , src , akt , and rsk-1 may phosphorylate dapk1 ( on y491/y492 , s308 , and s289 , resp . ) to maintain it in a repressed , inactive state ( figure 2 ) [ 143148 ] .
accordingly , the activation of integrins and fak results in the suppression of dapk1 activation .
it is however known that activated dapk1 contributes greatly to the destabilization of the cytoskeleton and is critical for membrane blebbing ( figure 3 ) [ 143146 ] .
dapk1 may furthermore deactivate integrins through an inside - out mechanism that involves the displacement and replacement of talin at the cytoplasmic tail of subunits , consequently resulting in disassembly of focal adhesions ( figure 3 ) [ 149151 ] .
interestingly , dapk1 phosphorylates beclin-1 , an autophagic cell death - driving factor [ 13 , 79 ] , in order to free it from inhibitory binding by bcl-2 and bcl - xl [ 145 , 146 ] . considering that experimental attempts at inhibiting intrinsic pathway apoptotic effectors following the induction of anoikis often fail to protect cells , resulting instead in their beclin-1-mediated autophagic death [ 2 , 710 , 118120 ] , the detachment - induced activation of dapk1 is therefore likely to constitute a functional bridge between anoikis and autophagic cell death . the fourth punch delivered against cell survival by the loss of integrin binding consists in the induction of the extrinsic pathway of apoptosis that is , casp-8 activation ( figure 3 ) [ 12 , 36 , 81 , 101 , 108 , 115 , 117120 ] .
although the activation of casp-8 constitutes an early / immediate event following the loss of integrin - mediated cell adhesion , the precise mechanisms that are responsible for such activation remain poorly understood .
a part of the puzzle lies with previous observations that both pro - casp-8 and activated casp-8 are associated with the cytoplasmic tails of 1 and/or 3 subunits of unligated integrins [ 152 , 153 ] .
interestingly , pro - casp-8 is found already associated with the cytoplasmic tails of integrin subunits under healthy / adhering conditions [ 108 , 153 ] , most likely due to the fact that pro - casp-8 often complexes with src following its inhibitory phosphorylation by the latter . nonetheless , the formation of a disc at unligated integrins as the causal agent for casp-8 activation remains contentious , despite reports from different cell types that casp-8 activation can be fadd - dependent in anoikis [ 109 , 110 , 154160 ] and that c - flip can inhibit the process [ 156 , 160 , 161 ] .
indeed , with fak and src being downactivated following detachment from the ecm , rip1 is freed from fak [ 109 , 110 ] , and pro - casp-8 is no more negatively phosphorylated by src ( see previous section ) [ 108 , 162 ] .
additionally , the concomitant downactivation of the pi3-k / akt and/or ras / raf / mek / erk pathways leads to a down - regulation of c - flip expression ( see previous section and figure 3 ) [ 12 , 60 , 81 , 116118 , 120 ] .
thus , rip1 , fadd and pro - casp-8 can complex to form the disc .
however , it turns out that fak - freed rip1 forms a fadd - dependent disc at the cytoplasmic domain of the death receptor fas . in hindsight , that is to be expected given that , in some cell types , the expression of fasl can be upregulated following the loss of integrin binding , or that anoikis can be attenuated / blocked by the inhibition of fas [ 12 , 81 , 109 , 110 , 115 , 116 , 118120 , 154 , 155 , 160 , 161 ] . yet in the end , rip1 does not form a disc at unligated integrins . furthermore
, it has been shown that fadd is not found associated with the cytoplasmic tails of 3 subunit - containing unligated integrins in human umbilical vein endothelial cells undergoing anoikis , despite the fact that pro - casp-8 and activated casp-8 are .
most perplexing is what has been reported recently in human keratinocytes . in these cells ,
bound 1 integrins contain the 1a subunit variant , whereas the 1b variant is expressed in the cytosol and apparently not part of any functional heterodimeric receptor .
as can now be expected ( see above ) , pro - casp-8 is found associated with the cytoplasmic tails of 1a subunits when those cells are adhering . upon loss of ecm binding ,
1a integrins are internalized so as to colocalize with the cytosolic 1b subunits , whereby pro - casp-8 somehow shuttles from the tails of the former to those of the latter in order to undergo activation in a fadd - independent manner .
hence , how exactly pro - casp-8 and/or activated casp-8 associate with subunits of unligated integrins , as well as the precise mechanisms responsible for casp-8 activation at these sites , remain open questions .
although it is not yet established whether dapk1 can contribute to the formation of a disc [ 143148 ] , the fact that activated dapk1 binds to the cytoplasmic tail of subunits of integrins it has deactivated [ 149151 ] definitively raises suspicions to that effect , especially in light of the previous observations in keratinocytes .
then again , it may simply be that the mechanisms of casp-8 activation following the induction of anoikis differ according to the combined contexts of the cell type , of the integrin repertoire expressed ( including variants ) , and of the species concerned not unlike everything else that has been discussed herein so far . in any case
, the activation of casp-8 following the loss of integrin binding is typically of low - intensity . as a result
, this leads to a likewise low intensity activation of executioner caspases ( section 2 ) .
hence , anoikis implicates the necessary following events : ( a ) caspase - mediated cleavage of bid into its active tbid form ; ( b ) caspase - mediated cleavage of pro - survival kinases ( e.g. , fak , akt ) for deactivation ; ( c ) caspase - mediated liberation of bmf and bim ( figure 3 ) [ 12 , 36 , 81 , 101 , 108 , 115 , 117120 ]
. moreover , mekk1 ( mitogen - activated protein kinase kinase kinase 1 ) , an upstream activator of the jnk pathway , may be cleaved by executioner caspases ( namely , casp-7 ) in order to generate a constitutive active form which is responsible for a consequent prolonged / sustained activation of jnk ( jnk1 presumably , [ 128 , 137 , 138 ] ) , who then undertakes apoptotic phosphorylating functions ( see above and figure 3 ) . consequently
, these events altogether effect a translocation of the death signal to mitochondria for the formation of the apoptosome and activation of casp-9 ( figure 3 ) .
interestingly , anoikis in normal cells is characterized by a delay in the irreversible commitment to the process following the triggering of its initial pro - apoptotic events [ 12 , 46 , 79 , 81 , 101 , 114 , 120 , 128 ] .
this explains why cells can be rescued from anoikis by reattachment within a limited time - span subsequent to their loss of anchorage [ 12 , 46 , 79 , 81 , 101 , 114 , 120 , 128 ] .
such a window of anoikis reversibility varies in length depending on the cell type and species , thus ranging from some fifteen minutes to four hours [ 12 , 46 , 79 , 81 , 101 , 114 , 120 , 128 ] .
it is thought that a window of anoikis reversibility depends primarily on the time - span required for the death signal to reach mitochondria , according to the specific integrins ( and variants ) implicated , the precise determinants of cell survival / death in play ( e.g. , bcl-2 homolog expression profiles , survival pathways / isoforms engaged , apoptotic kinases / isoforms involved , etc . ) , and the degree of cytoskeletal organization / cell polarity imparted not only by integrins ( i.e. , focal adhesions , hemidesmosomes ) , but as well by cell - cell interactions ( e.g. , e - cadherins ) .
indeed , the latter sensitize cells to anoikis by further linking / organizing the cytoskeleton , albeit contributing at the same time to cell survival signaling [ 12 , 46 , 81 , 114 , 115 , 128 , 163 , 164 ] .
additionally , it has been observed that the activation of pro - survival kinases such as src , akt and/or erk1/erk2 undergoes a short ( five to fifteen minutes in length ) , transient up - activation following the loss of anchorage .
while the mechanisms responsible for these deathly gasps remain unclear , they are first and foremost considered to act as a protection against transient detachments from the ecm , such as those required during normal cell processes like migration or cytokinesis .
accordingly , these may also contribute in defining a window of anoikis reversibility [ 12 , 46 , 79 , 81 , 114 , 120 ]
. however , considering the recent evidence that an up - activation of mek / erk in normal cells can actually trigger the intrinsic apoptotic pathway [ 165 , 166 ] , or activate dapk1 and a consequent autophagic cell death [ 148 , 149 , 165 , 166 ] , the question arises whether such deathly gasps may not in fact represent poisoned fruits .
be that as it may , it is clear that once casp-9 activation occurs , any window of reversibility is shut and anoikis becomes irreversible so much so , in fact , that attempts from this point on to inhibit the process result in beclin-1-driven autophagic cell death ( see above ) [ 2 , 710 , 118120 ] . to this effect
, this may explain why the overexpression of bcl-2 or bcl - xl alone can protect cells from anoikis [ 12 , 36 , 53 , 81 , 114 , 117120 , 128 , 137 , 167 ] , as such overexpression would not only manage to block the translocation of the death signal to mitochondria following detachment , but furthermore prevent the trigger of autophagic cell death by an overwhelming inhibitory binding to beclin-1 .
given that normal cells require a sound anchorage to their ecm in order to live , and in view of the four - punch hit
described above that occurs following the loss of integrin - mediated attachment , it is therefore usually considered that integrins suppress anoikis [ 12 , 81 , 101 , 120123 ] .
this is well exemplified by the observations that the forced expression of dominant negative mutants of fak and/or src readily induces anoikis , whereas the forced expression of constitutive active mutants of either , or both , protects against it [ 12 , 60 , 6373 , 81 , 99101 , 114 , 119 , 120 , 168 ] .
likewise , similar results are obtained when mutants of kinases that are engaged by integrin / fak / src - mediated cell survival signaling are used , such as pi3-k or akt [ 12 , 60 , 6373 , 81 , 81 , 8899 , 99 , 100 , 100 , 101 , 101 , 114 , 119 , 120 ] . however , there is now evidence that some integrins may actually sensitize cells to anoikis .
as example , the knockdown of the expression of 81 in human intestinal epithelial crypt cells results in the loss of vinculin at focal adhesions and confers a measure of anoikis resistance via an illicitly sustained activation of fak .
although it remains unclear by which mechanisms fak activation is thus sustained , it is germane that vinculin has been shown to enforce the adhesion - dependent activation / deactivation of fak [ 60 , 67 , 170 , 171 ] and that the gene disruption of vinculin in f9 mouse embryonic carcinoma cells renders them resistant to anoikis , also via a sustained activation of fak .
another example of anoikis - sensitizing integrin is v3 in colon cancer cells , although it is not known how this integrin enacts such a sensitizing function [ 172 , 173 ] .
it is thought that anoikis - sensitizing integrins may be part of the above - mentioned anchorage - dependent surveillance system , as a means to further warrant the disposal of cells that detach from their ecm .
however , it is already clear that anoikis - sensitizing functions will be undertaken by specific integrins according to the cell type .
indeed , v3 is better known for its anoikis - suppressing roles in endothelial cells , among other cell types [ 174 , 175 ] , whereas 81 has already been reported to suppress anoikis in myofibroblasts .
overall , the preceding considerations altogether demonstrate the multilayered complexities that underlie the regulation of cell survival , apoptosis , and anoikis .
moreover , these include further mechanistic distinctions according to the contexts of the composition of the ecm , the specific integrins implicated , the cell type , and the species .
however , studies in recent years in one tissue in particular , the human intestinal epithelium , have unearthed yet another level of intricacy in the regulation of these processes , namely , the implication of distinct mechanisms according to the state of cell differentiation .
the intestinal epithelium is an elegant and valuable physiological system for understanding the functional connections between integrin - mediated cell - ecm interactions and the cell state [ 101 , 125 , 177181 ] .
the continuous renewal of this simple columnar epithelium occurs along a well - defined unit , the crypt - villus axis .
this unit consists generally in two cell populations : the proliferative , immature cells of the crypt and the differentiated cells of the villus [ 125 , 126 ] . as part of the dynamic process of intestinal epithelial renewal ,
obsolete enterocytes enter anoikis upon reaching the apex of the villi , as a means of exfoliation [ 101 , 125 , 126 , 180 ] . for their part
, crypt cells can occasionally undergo apoptosis in order to evacuate daughter cells that are damaged or defective [ 101 , 125 , 126 , 180 ] .
such apparent contrast of destiny between undifferentiated and differentiated enterocytes along the crypt - villus axis , coupled with their specific profiles of expression of bcl-2 homologs which are established during the differentiation process [ 101 , 125 , 182186 ] , initially introduced the concept of a distinct modulation of cell survival and apoptosis according to the state of differentiation [ 101 , 125 , 184 ] .
this concept so far has been demonstrated mostly in human intestinal epithelial cells [ 101 , 125 ] .
for instance , the individual expression of bcl-2 homologs is subjected to specific regulatory mechanisms depending on the differentiation status of enterocytes [ 167 , 185187 ] .
as example , the pi3-k / akt-1 and mek / erk pathways are selectively implicated in the promotion of enterocytic survival according to the state of differentiation , including with regards to their modulation of the expression / activity of bcl-2 homologs ( figure 4 ) [ 167 , 185187 ] . in this respect ,
pi3-k / akt-1 , but not mek / erk , is critical for the survival of undifferentiated / crypt enterocytes , whereas both pathways are vital for the survival of differentiated / villus ones ( figure 4 ) [ 167 , 185187 ] .
the obvious follow - up question is whether the concept of a distinct modulation of cell survival and apoptosis according to the state of differentiation applies as well to integrin - mediated cell survival and anoikis . in effect ,
human intestinal epithelial crypt and villus cells express differential profiles of integrins as they interact with specific basement membrane components , which are likewise deposited differentially along the crypt - villus axis [ 125 , 177181 , 184 , 188 ] . as expected when considering the normal fate of villus cells ( see above ) , it turns out that differentiated / villus enterocytes are more susceptible to anoikis than their undifferentiated / crypt counterparts [ 185 , 189 , 190 ] .
although crypt cells express the 81 receptor as an anoikis - sensitizing integrin , the villus cells are nonetheless highly polarized in addition to bearing e - cadherin adherens junctions , in stark contrast to the former . moreover ,
such distinctions in anoikis susceptibility between crypt and villus enterocytes translate into differentiation state - specific mechanisms of integrin - mediated cell survival and anoikis ( figure 4 ) [ 167 , 185 , 186 , 189191 ] .
for instance , 1 integrins , fak , and src distinctively modulate the expression / activity of bcl-2 homologs depending on the enterocytic differentiation status ( figure 4 ) [ 167 , 185 , 186 , 190 ] .
furthermore , 21 , 51 , and 6a1 are required for the survival of undifferentiated enterocytes , whereas 31 , 6b1 and 6b4a are required for the survival of differentiated ones [ 185 , 186 ] ( s. thibodeau and p.h .
similarly , the engagement of pi3-k / akt-1 is integrin 1/fak / src - dependent in undifferentiated cells , but src - independent in differentiated ones , whereas the engagement of mek / erk remains integrin 1/fak / src - dependent regardless of the state of differentiation ( figure 4 ) [ 167 , 185 , 186 , 189191 ] . to this effect , the integrin 1/fak / src / pi3-k / akt-1 pathway antagonizes the apoptotic activation of p38 in undifferentiated enterocytes , whereas the integrin 1/fak / pi3-k / akt-1 and integrin 1/fak / src / mek / erk pathways both contribute in antagonizing that of p38 , in differentiated ones ( figure 4 ) [ 167 , 186 , 189 ] .
consequently , the regulation of integrin - mediated cell survival and anoikis is indeed subjected to differentiation - state - specific mechanisms ( figure 4 ) .
however , the overall concept of differentiation state - specific controls of cell survival , apoptosis , and anoikis does not constitute a peculiarity of the intestinal epithelium , since it evidently applies to other tissues albeit not without obligatory cell type- and/or species - dependent distinctions .
for instance , skeletal muscle myoblasts require fibronectin and 51a in order to survive , whereas myocytes require instead laminin-211 and 7b1d [ 5053 ] .
furthermore , myoblasts depend on an integrin - driven fak / src / mek / erk pathway for their survival , whereas myocytes depend instead on an integrin - driven fyn / pi3-k / akt-2 one [ 52 , 53 , 192 , 193 ] . a fundamental challenge now presenting itself lies in the search for answers to three broad questions regarding such differentiation state - specific mechanisms of cell survival , apoptosis and anoikis , namely : ( a ) the why for the existence of such distinct mechanisms according to the state of cell differentiation ; ( b ) the how of these distinct mechanisms ( i.e. , the further functional identification of specific extracellular ligands , integrins and molecules / pathways involved , as well as their respective differentiation - specific roles in the suppression or induction of apoptosis / anoikis ) ; ( c ) the in what capacity these same differentiation - specific mechanisms contribute in the emergence of diseases when they become deregulated .
as in the case of apoptosis , there is an increasing number of pathological disorders that are characterized by a deregulation of integrin - mediated cell survival , and anoikis signaling [ 35 , 39 , 44 , 49 , 117 , 118 , 120 , 194 ] .
certain forms of muscular dystrophy and epidermolysis bullosa constitute classic examples of pathologies that are caused primarily by a deregulated induction of anoikis [ 39 , 44 , 79 , 80 , 195197 ] .
accordingly , the need to understand the regulation of cell survival and apoptosis has gained much importance in cancer research , especially since the acquisition of a resistance to anoikis constitutes a critical step in tumor progression particularly in the emergence of invasive and metastatic cells [ 86 , 116 , 118120 , 174 , 188 , 198200 ] . incidentally , cancer cells are notorious for exhibiting major alterations in their repertoire of expressed integrins [ 49 , 62 , 80 , 86 , 174 , 180 , 188 , 199 , 200 ] , as well as in their surrounding ecm [ 35 , 49 , 180 , 188 , 200 ] . moreover , metastatic cells are infamous for displaying a marked resistance to anoikis [ 86 , 116 , 118120 , 174 , 188 , 198200 ] . to this effect
, much attention has been given to fak and src in tumor progression [ 6373 , 201 ] , as well as to downstream pathways engaged by them , such as pi3-k / akt and mek / erk [ 8899 ] .
along with these , virtually every known player in the intrinsic and extrinsic pathways of apoptosis is likewise being scrutinized , in order to not only seek an eventual understanding of the acquisition of resistance to anoikis ( and/or apoptosis ) by cancer cells , but as well as to identify molecular targets that are susceptible to shut down such problematic resistance .
thus , anoikis - sensitizing integrins may be added to this expanding list , in view of the observations that anoikis - resistant colon cancer cells do not express 81 , whereas forcing its expression reinstates in them a good measure of susceptibility to anoikis .
similarly , colon cancer cells that are anoikis - sensitive acquire a resistance to the process following their loss of expression of v3 .
however , the cross - talk between integrins and rtks further complicates matters greatly , since the deregulated activity of an rtk can confer resistance to anoikis by maintaining / enhancing integrin - mediated cell survival after the loss of attachment , via inside - out signaling [ 12 , 34 , 86 , 87 , 116 , 117 , 119 , 120 , 174 , 175 ] .
as one example among many , colon cancer cells that strongly express egf / tgf- ( epidermal growth factor / transforming growth factor- ) display a resistance to anoikis by at least in part sustaining the activation of src via autocrine stimulation of egfr ( egf receptor ) , therefore allowing src to maintain functional interactions with fak and consequently sustaining a fak / src - mediated suppression of anoikis . in this respect ,
the deregulation of rtk signaling is well known to induce epithelial - mesenchymal transition ( emt ) in normal epithelial cells , a phenotypic change that is considered a prerequisite for the acquisition of anchorage - independent growth and resistance to anoikis , consequently leading to the emergence of invasive and metastatic cancer cells [ 62 , 6673 , 8587 , 116 , 119 , 120 , 200 , 201 , 203 ] .
hence , the task of elucidating the mechanisms of resistance to anoikis in cancer cells , let alone identifying commonalities , is evidently proving to be a daunting one and that is without taking into account the inherent molecular differences between the various types of cancers , as well as the cellular and molecular heterogeneity that is invariably found within any given cancer .
nevertheless , increasing our knowledge of those determinants which control cell survival , apoptosis , and anoikis within a specific tissue will , in turn , add further to our comprehension of apoptosis / anoikis - linked diseases of said tissue , in addition to paving the way toward the design of targeted molecular therapeutic approaches that are both tissue- and disease - selective . to this end ,
the inclusion of acquiring a better grasp of differentiation state - specific distinctions in the integrin - mediated regulation of cell survival and anoikis in such research endeavors would not only allow for a more complete understanding of a given tissue 's normal physiology , but furthermore provide a full accounting of the physiopathological underpinnings of its apoptosis / anoikis - linked diseases including tumorigenesis and tumorigenic progression . incidentally , cancerous intestinal epithelial cells display integrin / fak / src anoikis - suppressing signaling features that are similar to either their normal undifferentiated or differentiated counterparts , and do so regardless of their own degree of cell dedifferentiation . whether or not cancer cells of other tissues do likewise remains , however , to be confirmed .
cells require survival signals in order to live , and interactions with their ecm through integrins constitute a critical contributor to this effect .
integrin - mediated cell survival and anoikis comprise a multifaceted and multilayered surveillance mechanism which is responsible for upholding the correct position of cells within their respective tissues , thereby sentencing to death any cell that would stray from its assigned position by either interacting with an inappropriately composed ecm or by losing anchorage to its own ecm .
thus , anoikis partakes greatly in the configuration and preservation of the proper functional organization of tissues , thereby ensuring the disposal of cells that assume a roguish behavior with regards to their precise integrin - ecm adhesion requirements for survival whether this occurs accidentally in the course of normal physiological processes , such as tissue renewal , or otherwise .
it is undeniable that the regulation of cell survival and anoikis implicates distinct mechanisms according to the composition of the ecm , the repertoire of integrins ( and variants ) expressed , the degree of cell polarity ( i.e. , cytoskeletal organization ) conferred at least in part by specific ecm - integrin interactions , the transduction pathways engaged and/or suppressed through signaling by individual integrins , the isoforms and/or family members participating in such pathways , the rtks expressed which may , or may not , interfere with their intrusive cross - talk , and the various regulators / effectors of apoptosis that are expressed .
although there may be a measure of mechanistic commonality between some cell types , one should always be mindful of the reality that the integrin - mediated control of cell survival and anoikis constitutes a complex business that is not only tissue type- and species context - dependent , but as well differentiation state - distinctive .
taking into account these caveats should allow for an improved focusing on the precise determinants of cell survival of a given tissue within the whole of its physiological framework , therefore facilitating an eventual elucidation of the selective integrin - mediated underpinnings that are implicated in tissue - specific apoptosis / anoikis - linked pathological disorders .
Output:
| cell survival and apoptosis implicate an increasing complexity of players and signaling pathways which regulate not only the decision - making process of surviving ( or dying ) , but as well the execution of cell death proper .
the same complex nature applies to anoikis , a form of caspase - dependent apoptosis that is largely regulated by integrin - mediated , cell - extracellular matrix interactions .
not surprisingly , the regulation of cell survival , apoptosis , and anoikis furthermore implicates additional mechanistic distinctions according to the specific tissue , cell type , and species .
incidentally , studies in recent years have unearthed yet another layer of complexity in the regulation of these cell processes , namely , the implication of cell differentiation state - specific mechanisms . further analyses of such differentiation state - distinct mechanisms , either under normal or physiopathological contexts , should increase our understanding of diseases which implicate a deregulation of integrin function , cell survival , and anoikis . |
PubmedSumm118637 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: despite advances in knowledge , malaria continues to cause significant morbidity and mortality worldwide . over 40% of the world population
lives in malaria - endemic areas and it is very high ( 20% ) in severe malaria ( parasitaemia > 5% ) .
today malaria is the most important problem for which an estimated 300500 million cases were recorded and 1.52.7 million deaths occur each year . among them
mortality rate usually depends on the management of malaria which involves antimalarial drug resistance of plasmodium falciparum and occurrence of systemic complications .
variations in haematological parameters are influenced by any disease condition which affects the haemopoietic physiology .
this is likely to happen with an endemic disease such as malaria that affects the host homeostasis .
the target of malaria parasite is rbc so that peripheral blood smear examination is the major diagnostic tool of the disease .
microscopic diagnosis is the imperfect gold standard for malaria parasite detection and species identification .
however , it is a valuable technique when performed correctly in the right hands but can be unreliable and perceived as useless when poorly executed [ 6 , 7 ] .
haematological changes associated with malaria infection are well recognized , but specific changes may differ from the level of malaria endemicity , background haemoglobinopathy , nutritional status , demographic factors , and immunity to malaria . hence , haematological changes are the most common and important complications encountered and are considered a hallmark of malaria , playing a major role in the fatality .
prediction of the haematological changes enables the clinician to establish an effective and early therapeutic intervention in order to prevent the occurrence of major complications .
the haematological abnormalities that have been reported include anaemia , thrombocytopenia , lymphocytosis and rarely disseminated intravascular coagulation , leucopenia , leucocytosis , neutropenia , neutrophilia , and eosinophilia , and monocytosis also have been reported [ 10 , 11 ] .
artemisinin(s ) monotherapy and combination therapy ( acts ) are currently used as first line treatment for uncomplicated malaria .
artesunate is a semisynthetic derivative of artemisinin consisting of sodium succinyl salt of dihydroartemisinin , a potent blood schizonticide highly effective against multidrug resistant strains of p. falciparum .
, arteether ( 30 : 70 mixture of enantiomers ) is a fast - acting blood schizonticide completed multicentric clinical trials in p. falciparum endemic areas and was found to be effective and marketed in 1997 as e mal .
arteether has a higher safety margin compared to other artemisinin derivatives , has longer half - life , and produces high cure rates when administered in a short 3-dose ( i.m . )
artemether + lumefantrine combination combines the benefits of a rapid short - lived schizonticidal effect of arteether with a slower but longer acting schizonticidal effect of lumefantrine , a highly lipophilic aryl amino alcohol .
the present study was aimed to reveal the effect of 3 frequently used artemisinin derivatives , namely , artesunate ( oral ) , arteether ( i.m . ) , and artemether + lumefantrine ( oral ) on haematological parameters .
the present investigation was also aimed to study the course of infection in falciparum - infected and drug - treated mice to know the efficacy of artemisinin derivatives based on parasite clearance time ( pct ) .
thus the aim of our study was to investigate the different hematological changes with p. falciparum malaria and to define the possible role of plasmodium species in the pathogenesis related to haematological changes .
c57bl/6j male mice of age of 10-week - old were purchased from national centre for laboratory animal sciences ( n.c.l.a.s ) , national institute of nutrition ( nin ) , hyderabad , india , and allowed to acclimatize for 15 days .
animals were fed with standard feed daily and water was given adlibitum at room temperature of 24 5c with 12 hrs .
the study was conducted in accordance with guidelines in the guide of the care and use of laboratory animals . for the present experiment
the species of p. falciparum was collected from an infected person from government general hospital in guntur , andhra pradesh .
patient is tested with sd bioline malaria rapid test ( p.f / p.v ) and blood smear examination by 10 to 15 years experienced microbiologist who confirmed p. falciparum with high parasitaemia . at the time of blood collection the patient does not receive any preantimalarial treatment even paracetamol .
the blood containing p. falciparum was extracted from peripheral vein of hand of the infected individual using 5 ml sterile syringe .
immediately blood was transferred to edta vacutainer ( bd franklin , usa ) ; kept in thermocol ice box , and transferred to the laboratory .
the collected blood was washed several times in phosphate buffered saline ( pbs , ph 7.0 ) by centrifugation at 1000 rpm/15 min .
the washed erythrocytes were suspended in pbs and packed by centrifugation , and supernatant was removed by a pipette . the sediment with p. falciparum - infected erythrocytes was diluted with pbs . after obtaining p. f. antigen , the parasites were maintained experimentally in three c57bl/6j male mice , and the level of parasitaemia was monitored after the next day of inoculation by smear preparation . after the achievement of high level of parasitaemia ( stock blood ) , blood samples were collected and diluted in normal saline at the ratio of 75% parasitized blood and 25% pbs .
the diluted parasitized blood was then inoculated into different experimental mice groups on day 0 via intraperitoneal ( i.p . )
route because malaria parasite penetrates the peritoneal wall into the blood stream within one minute of inoculation .
mice of control group were inoculated with distilled water on day 0 and maintained as control .
a total number of 40 c57bl/6j male mice were distributed into 5 groups , namely , control ( con ) , infected ( inf ) , drug treated with artesunate ( dt as ) , drug treated with arteether ( dt ae ) and drug treated with artemether + lumefantrine ( dt al ) of 8 animals each . for all drug - treated groups , therapeutic dosages according to who recommendation were administered .
doses were calculated according to the average body weight of the mice ( approximately 30 gm / mouse ) . for monotherapy , artesunate ( as ) tablets ( falcigo ) from zydus
cadila health care limited , india , and arteether ( ae ) ( e mal ) from themis chemicals limited , mumbai , india , were obtained . for combination therapy , artemether
+ lumefantrine ( al ) ( lumerax-20 dt ) from ipca laboratories limited , india , was obtained.artesunate : through oral gavage in 4 ( double divided dose ) , 2 , 2 , 2 , and 2 mg / kg body weight for five days .
arteether : intramuscularly in 3 mg / kg body weight for three days.artemether + lumefantrine : through oral gavage in 3.5 mg / kg body weight for three days .
artesunate : through oral gavage in 4 ( double divided dose ) , 2 , 2 , 2 , and 2 mg / kg body weight for five days .
artemether + lumefantrine : through oral gavage in 3.5 mg / kg body weight for three days .
parasitaemia was monitored daily up to day 42 by making peripheral blood smears .
comparison of parasitaemia between infected mice and drug - treated mice revealed the efficacy of each drug used for the study .
thin blood films were made on the prelabelled slide with free flowing whole blood directly from the mouse tail snips after the first drop was wiped off with cotton wool .
the blood films were stained with jsb i and jsb ii for the detection of malarial parasites and for estimation of parasitaemia . after staining ,
slides were washed with tap water to remove excess stain and allowed to drain in a vertical position and to air dry .
a field was selected where the rbcs are in an evenly distributed monolayer and observed under 100x oil immersion objective .
a minimum of 1000 rbcs were counted from 10 fields under microscope , and the number of infected rbcs will be recorded .
the percent of parasitaemia was determined by enumerating the number of infected rbcs per total number of rbcs counted ( 5 ) :
( 1)parasitaemia%=no . of infected rbcsno . of rbcs counted100 .
parasite clearance time ( pct ) was defined as the time from the start of treatment until first negative blood smear for asexual stages which remained negative for an additional 24 hours . for our study
thus pct was observed in all the experimental groups . at the end of the series of experiments ( i.e. , after achieving first negative blood smear )
, 6 animals in all the drug - treated groups were sacrificed using chloroform anaesthesia .
six animals in infected and six animals in control group were sacrificed on day 28 .
two animals in all the groups kept for 42 days , and one animal is used to calculate parasitaemia on each day .
blood samples were collected by cardiac puncture into edta vacutainer to see the frequency of haematological abnormalities especially anaemia , thrombocytopenia , and reduced blood counts in malaria .
whole blood was immediately analyzed for complete blood picture ( cbp ) , that is , red blood cell ( rbc ) count , haemoglobin ( hgb ) , hematocrit ( hct ) , mean cell volume ( mcv ) , mean cell haemoglobin ( mch ) , mean cell haemoglobin concentration ( mchc ) , white blood cell ( wbc ) count , and platelet ( plt ) count using the fully automated abx pentra 60 + analyser ( horiba abx , montpellier , france ) .
briefly , 53 l of blood was aspirated into a needle divided and distributed to the various chambers for sample analysis .
the means , standard deviations of normally distributed data were compared between control versus infected group and infected versus drug - treated groups using student 's t - test with minitab 11.12.32 .
the values were given as mean sd and are statistically significant at t > 2.306 , p < 0.05 * ( significant ) , p < 0.001 * * ( more significant ) , and p < 0.0001 * * * ( highly significant ) .
in the present study , p. falciparum erythrocytic stages were developed in the blood of c57bl/6j mouse model after inoculation of 0.3 ml . of p. f antigen intramuscularly to the experimental mice .
various stages of parasite are seen in the blood films stained with jsb - i and jsb - ii solutions .
the blood films were scanned under high power objective ( 40 ) and examined closely under oil immersion objective ( 100 ) .
the various erythrocytic stages of p. falciparum were seen such as trophozoites ( immature and mature ) , schizonts , and gametocyte .
appearance of ring forms at the edge of rbc is the characteristic feature of plasmodium falciparum species ( figure 5 ) .
the erythrocytic stages observed were as follows.immature trophozoite : undivided nucleated cells with blue - coloured cytoplasm or a ring of cytoplasm within the red cell.mature trophozoite : compact cytoplasm , enlarged amoeboid shape , and no ring structure .
immature trophozoite : undivided nucleated cells with blue - coloured cytoplasm or a ring of cytoplasm within the red cell .
mature trophozoite : compact cytoplasm , enlarged amoeboid shape , and no ring structure .
after inoculation of p. f. antigen on day 0 into the mice of infected ( inf ) group , the parasites started developing in the peripheral blood from day 1 onwards and reached to peak level on 11th day with 38% parasitaemia .
then the parasitaemia gradually decreased and completely disappeared by day 28 ( figure 1 ) .
after inoculating p. f. antigen to mice of dt as group , parasitic ring stags have appeared on 1st day .
then artesunate drug was administered orally for the next 5 days successively with 2 mg / kg body weight with a double divided dose on the first day . after treating the mice with drug , the peak level of infection
but the blood smears were examined till the 42nd day and no parasites were observed ( figure 2 ) .
the parasite clearance time ( pct ) was 144 hours ( 6 days ) with artesunate .
after inoculation of p. f. antigen to mice of dt ae group , parasitic ring stags have appeared on the 1st day .
after arteether treatment , the peak level of infection was observed on day 2 with 4.2% parasitaemia
. then the parasites were completely disappeared by the 5th day ( figure 3 ) .
the parasite clearance time ( pct ) was 120 hours ( 5 days ) with arteether .
after giving p. f. antigen to the mice in dt al group , parasitic ring stages have appeared on the 1st day .
then artemether + lumefantrine ( artemisinin based combination therapy ) was administered orally for the next three days . with the combination therapy , peak level of infection
was observed on day 3 with 3.2% parasitemia , and no parasites were observed on day 4 till the 42nd day ( figure 4 ) .
the parasite clearance time ( pct ) was 96 hours ( 4 days ) with artemether + lumefantrine .
table 1 shows changes in haematological values between control versus infected group . in the infected group
the mean value for hgb is 7.93 0.175 ( p < 0.0001 ) , rbc is 5.9 0.201 ( p < 0.0001 ) , pcv is 2892 1.46 ( p < 0.0001 ) , mcv is 81.07 2.19 ( < 0.0001 ) , mch is 27.67 1.17 ( 0.0001 ) , plt is 516 23.4 ( < 0.0001 ) , wbc is 6957 102 ( < 0.0001 ) , neutrophils is 28.3 0.724 ( p < 0.0001 ) , lymphocytes is 69.70 2.00 ( p < 0.0001 ) , and eosinophils is 1.0 0.669 ( p < 0.014 ) . and these values
were significantly decreased when compared to the control values ( 12.85 0.321 , 8.0 0.141 , 38.67 1.97 , 91.48 1.64 , 32.33 1.26 , 685 20.7 , 9080 98.9 , 36.15 0.693 , 59.85 2.00 , and 2.0 0.187 ) , respectively .
mchc ( 33.17 1.08 , p > 0.05 ) and monocytes ( 1.0 0.190 , p > 0.05 ) have not shown significant change in the infected group when compared to control values ( 34.42 1.12 , 1.0 0.228 ) , respectively .
table 2 shows changes in haematological values in infected ( inf ) versus artesunate drug - treated ( dt as ) group .
< 0.0001 ) , pcv ( p < 0.01 ) , mcv ( p < 0.01 ) , plt ( p < 0.0001 ) , wbc ( p < 0.001 ) , neutrophils ( p < 0.0001 ) , lymphocytes ( p < 0.0001 ) , and eosinophil ( p
mch ( p > 0.05 ) , mchc ( p > 0.05 ) , and monocytes ( p > 0.05 ) did not show statistically significant difference between inf and dt as groups
.
table 3 shows changes in haematological values in infected ( inf ) versus arteether drug - treated ( dt ae ) group .
hgb ( p < 0.0001 ) , rbc ( p < 0.0001 ) , pcv ( p < 0.05 ) , plt ( p < 0.0001 ) , wbc ( p < 0.001 ) , neutrophils ( p < 0.0001 ) , lymphocytes ( p
< 0.0001 ) , and eosinophil ( p < 0.05 ) values were significantly increased in dt ae group when compared to inf group .
mcv ( p > 0.05 ) , mch ( p > 0.05 ) , mchc ( p > 0.05 ) , and monocytes ( p > 0.05 ) have not shown significant change in dt ae group when compared to inf group .
table 4 shows changes in haematological values in infected ( inf ) versus artemether + lumefantrine drug - treated ( dt al ) group .
< 0.01 ) , mcv ( p < 0.001 ) , plt ( p < 0.0001 ) , wbc ( p < 0.001 ) , neutrophils ( p < 0.0001 ) , lymphocytes ( p < 0.01 ) , and eosinophil ( p < 0.05 ) in artemether + lumefantrine - treated group have significantly increased when compared to the infected group .
insignificant changes were observed for mch ( p > 0.05 ) , mchc ( p > 0.05 ) , and monocytes ( p > 0.05 ) between inf and dt al groups .
the peripheral blood parasite count is the prognostic indicator that correlates with the total parasite biomass and thus the severity of falciparum malaria .
haematological abnormalities are considered a hallmark of malaria and reported to be the most pronounced in p. falciparum infection , probably as a result of the higher levels of parasitaemia .
this study was conducted to assess and compare the incidence and severity of haematological changes in falciparum - infected c57bl/6j mice using an experimental model . in this study
we observed that there is a marked reduction in rbc count , wbc count , haemoglobin ( hgb ) , packed cell volume ( pcv ) , mean cell volume ( mcv ) , and platelet counts in falciparum - infected mice when compared to control animals .
it is thought to result from a combination of haemolysis of parasitized red blood cells , accelerated removal of both parasitized and innocently unparasitized red cells , depressed as well as ineffective erythropoiesis with dyserythropoietic changes , and anaemia of chronic disease .
other factors contributing to anaemia in malaria include decreased red blood cell deformability , splenic phagocytosis , and/or pooling .
malaria parasite within rbcs , ingest and digest haemoglobin more than it needs for its own metabolism .
destruction of rbc following parasitisation can not account for the degree of anaemia observed during malaria infection , suggesting that the destruction of uninfected rbc ( urbc ) is the major cause of haemoglobin ( hgb ) loss .
the low pcv value with a correspondent high density of malaria parasite was suggested to be due to excessive destruction of red blood cells by the malaria parasites .
as noted in this study , it was established that the more malaria parasites in the blood circulation cause more destruction of the red blood cells as demonstrated by the low pcv .
the low pcv may necessitate the need for blood transfusion which in turn has a high risk of transmitting viral hepatitis , hiv , and other associated risks .
statistically insignificant changes were observed in mchc ( p > 0.05 ) and monocyte ( p > 0.05 ) values in infected mice when compared to control mice .
mchc levels were not significantly changed which is consistent with the earlier reports . in our study
we observed that there was a significant reduction in total wbc counts ( p < 0.0001 ) .
leucopenia appears to be a common finding in both nonimmune patients with falciparum malaria and semi - immune children living in malaria - endemic regions .
the differential leucocyte count showed normal monocytic , eosinophilic counts and decreased neutrophilic counts . similarly in the majority of cases , either neutropenia or neutrophilia was reported .
phagocytosis of malaria pigment is by monocyte / macrophages and less frequently by neutrophils [ 15 , 20 , 21 ] .
monocytes and rarely neutrophils contained malaria pigment and in very rare cases , erythrophagocytosis by monocytes was also observed in some studies .
our findings also showed that artemisinin(s ) given at the therapeutic doses may not cause neutropenia , which is consistent with prior studies [ 22 , 23 ] .
lymphocytes , particularly t cells , play a major role in immunity to falciparum malaria by releasing proinflammatory cytokines
. however excessive secretion of proinflammatory cytokines has been shown to contribute to the severity in humans [ 2426 ] .
our study showed that mice infected with falciparum had a higher lymphocytic count , and this may represent overstimulation of the proinflammatory pathway .
further studies on the role of lymphocytes are required to determine the significance of our findings .
it is a general consensus that thrombocytopenia is very common in falciparum malaria [ 27 , 28 ] and usually believed that a significant reduction in platelet counts ( p < 0.0001 ) than control animals .
thrombocytopenia seems to be due mainly to a reduced platelet life span and splenic pooling .
the reduced platelet life span may be caused by binding of malaria antigen onto platelets followed by antibody - mediated phagocytosis or to platelet activation in vivo .
the release of platelet contents can activate the coagulation cascade and contributes to decreased inhibitors concentration and consequently further thrombocytopenia .
artemisinin derivatives are most effective against plasmodium parasite ( as monotherapies ) ; combination therapies consisting of artemisinin(s ) and other antimalarial drugs have been demonstrated to have better parasite clearance and efficacies [ 3234 ] .
antimalarial treatment with artemisinin or one of its derivatives is associated with a more rapid decline in parasitaemia than with other antimalarial drugs .
fe , these drugs generate carbon centered free radicals that could damage the rbc membrane or cytoskeleton and thereby increase the rigidity of the infected rbc .
artesunate , by acting on young ring forms , attenuated the reduction in deformability parasite , prevented their development to more rigid mature trophozoites , and thereby attenuated the reduction in deformability associated with continued parasite growth .
artesunate induces changes either in the parasite or in the rbc directly and led to increased antigenicity and thus increased opsonization .
terminal half - lives of the orally administered drugs are usually less than 2 h. we observed that once daily administration with artemisinin derivatives provides equivalent cure rates to more frequent administration which is consistent with prior studies [ 36 , 37 ] . in artesunate group peak of parasitaemia on day 3 with 3.5% and parasites were completely cleared on day 6 .
the peak level of parasitaemia was reduced when compared to ae - treated group ( 4.2% on day 2 ) .
insignificant changes were observed in mch ( p > 0.05 ) , mchc ( p > 0.05 ) , and monocytes ( p > 0.05 ) for artesunate - treated group .
alpha beta arteether is an ethyl derivative of artemisinin which is an efficient schizonticidal drug in mild malaria .
the clinical efficacy of arteether is characterized by an almost immediate onset and rapid reduction in parasitaemia , with complete clearance in most cases within 48 hours .
but in our study we observed delayed parasite clearance time in ae - treated groups when compared to previous studies . in arteether group parasites cleared on day 5 .
we observed positive blood smears for one additional day after the completion of 3-day drug course .
the peak level of parasitaemia ( 4.2% on day 2 ) was increased when compared to as - treated group ( 4 on day 2 ) .
insignificant changes were observed in mcv ( p > 0.05 ) , mch ( p > 0.05 ) , mchc ( p > 0.05 ) , and monocytes ( p > 0.05 ) for arteether - treated group .
no adverse effects were observed on hematological parameters when animals - treated with , arteether which are consistent with prior studies [ 38 , 39 ] .
the levels of efficacy are similar to the findings of the recent studies on acts in africa which revealed that al has higher efficacy rates when compared to other antimalarials [ 4043 ] . in our study
we observed rapid parasite clearance in artemether + lumefantrine - treated group in comparison with artesunate- and arteether - treated animals which are in agreement with previous studies .
artemisinin(s ) can be used alone , but this leads to high rate of recrudescence ( return of parasites ) , and there is a possibility of emergence of resistant strains to the single drug treatment on repeated and inappropriate use and other drugs are required to all parasites and to prevent recrudescence .
but there is a marked variation in peak level parasitaemia and clearance time . in al group parasites cleared on day 4 .
we observed positive blood smears for one additional day after the completion of 3-day drug course .
the peak level of parasitaemia ( 3.2% on day 3 ) was decreased when compared to as- ( 4% ) and ae- ( 4.2% ) treated groups .
the rate of parasite clearance was used as a measure of the artemisinin pharmacodynamic effect in vivo .
we found higher efficacy rates when animals were treated with combination ( al ) drug than monotherapy .
when compared to as and ae groups , al group showed higher efficacy rates by clearing parasites on day 4 .
insignificant changes were observed in mchc ( p > 0.05 ) 0 and monocytes ( p > 0.05 ) for artemether + lumefantrine - treated group .
considering the higher efficacy rates of artemether + lumefantrine ( al ) as compared with artesunate ( as ) and arteether ( ae ) , we conclude that al is clinically more effective than as and ae .
no adverse effects were observed on haematological parameters when animals were treated with artemisinin derivatives .
artemisinin resistance is characterized by prolongation in clearance times which we observed in the present study .
the result of falciparum positive blood smear in all treatment groups on day 3 ( 72 h ) was a good predictor for treatment failure and considered as a simple screening measure for artemisinin resistance .
Output:
| to find out the efficacy and effect of artemisinin derivatives on haematological indices , c57bl/6j mice were challenged with plasmodium falciparum and treated with therapeutic doses of as , ae , and al .
course of infection was studied in the infected and treated groups up to day 42 .
peak level of parasitaemia ( 38% ) was observed on day 11 in infected group .
haematological indices indicated significant ( p < 0.05 ) decrease in rbc , wbc , haemoglobin , packed cell volume , mean cell volume , and platelet counts in infected mice . but all the parameters were restored to normal values , and significant ( p < 0.05 ) changes were observed in all drug - treated groups .
insignificant changes were observed for mchc ( p > 0.05 ) in all drug - treated groups .
percent of peak parasitaemia was much reduced in al- ( 3.2% on day 3 ) treated group in comparison with ae- ( 2.4% on day 4 ) and as- ( 4% on day 2 ) treated groups .
parasites were completely cleared on day 6 in as group , day 5 in ae group , and day 4 in al group .
hence , our results strongly support that combination therapy has high efficacy rates than monotherapy .
no adverse effects were observed on haematological parameters when animals were treated with therapeutic dosages . |
PubmedSumm118638 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: american trypanosomiasis , a chronic systemic parasitosis also known as chagas disease ( cd ) , is caused by the protozoan kinetoplastid parasite trypanosoma cruzi .
cd has afflicted humanity since its earliest presence in the new world and is still the largest parasitic disease burden of the american continent .
the disease is technically a zoonosis , as the natural reservoirs of the t. cruzi are a large variety of marsupial and placental mammals autochthonous to the american continent , the parasite being naturally transmitted among them by reduviid ( triatominae ) hematophagous insects . human disease results from the invasion of natural ecotopes , as well as from the establishment of the vectors in human dwellings , due to the poor socioeconomic conditions of most rural human populations from mexico to argentina , where the disease is endemic .
vector - borne transmission to humans initiates when the infected triatomine bug defecates after a blood meal .
the metacyclic trypomastigotes present in fecal droplets enter through the bite wound or by direct contact with mucosal membranes causing infection .
the parasite can also be transmitted congenitally from infected mothers to newborns , by transfusion of contaminated blood , organ transplants and orally by ingestion of contaminated foods and drinks .
these routes of transmission , together with intense international migrations in recent decades , have led to the spread of the disease to non - endemic areas , such as the u.s . ,
according to world health organization , in 2015 , about 67 million people are estimated to be infected with t. cruzi worldwide and responsible for 12,000 deaths annually , mostly in 21 endemic latin american countries .
three countries , argentina , brazil and mexico , concentrate more than 60% of cases , followed by bolivia and colombia . in the us it has been estimated that 2% of approximately 17 million latin american immigrants in 2007 , were potentially infected with t. cruzi ; of these , approximately 65,000 might have or may develop signs and symptoms of chronic cd . it is estimated that between 63 and 315 acquire t. cruzi infection in the u.s every year . based on these estimates , chagas cardiomyopathy may affect approximately 30,00045,000 persons in the united states , . according to the pan american health organization ( paho )
, congenital transmission appears to account for more than 25% of the world new cases of cd . in the united states
there is great concern for potential congenital transmission of t. cruzi from infected mothers to infants .
the first documented case of congenital transmission in the united states was recorded in 2012 .
the patient was born by cesarean section at 29 weeks of gestational age due to fetal hydrops from an asymptomatic mother with history of chagas disease diagnosed in bolivia ( country of origin ) , but never treated for the infection .
we report two adult male siblings with presumptive congenital transmission of t. cruzi , born in the united states to a bolivian seropositive mother , who had a strong epidemiological exposure to triatomine insects 28 years prior to her migration to the united states .
case 1 : a 24-year - old hispanic male was referred by the florida health department for evaluation after a voluntary blood donation serology for cd tested positive in september 2014 .
the patient was born and raised in the state of maryland ( silver spring ) and at the age of 5 moved to miami , florida .
the patient had no exposure to potential sources of infected vectors , such as sub - standard housing ( i.e. cracks on the walls and foundations of homes made of adobe / mud , thatched roofs ) and/or potential animal reservoirs and infected vectors , either in the united states or during his four visits , for less than two weeks each , to la paz city in bolivia .
an interview with the patient s mother revealed that during his childhood , the patient never visited or stayed in high endemic rural areas for cd in bolivia .
past medical history : in may 2013 , the patient was evaluated for left sided chest pain in the emergency department of one of the local hospitals .
seven months later , an outpatient follow up evaluation showed no symptoms and his general physical examination was normal .
laboratory work showed a normal blood cell count , chemistry ( bun , creatinine , electrolytes ) , and liver function tests ( alt , ast ) .
the patient never received a blood transfusion and reported a non - complicated dental surgery . in february 2015 , a new ekg revealed an incomplete right bundle branch block ( rbbb ) and first - degree atrioventricular ( av ) block ( fig .
a t. cruzi enzyme immunoassay ( ab eia ) , was reactive : od 2.747 ( reactivity : od > 0.330 ; sens . 100% , spec .
both tests were performed at the center for disease control and prevention ( cdc ) .
the patient was treated orally with nifurtimox at 10 mg / kg , daily , divided in three doses , for 90 days .
the patient completed the treatment and only reported loss of appetite and weight during drug administration .
follow up laboratory work ( complete blood count , basic chemistry analysis and liver function tests ) was normal .
case 2 : as a result of an extended epidemiological family questioning analysis , the patient s only sibling was contacted for evaluation .
the patient is a 26 year - old male , who was diagnosed to have a positive serology for t. cruzi in 2008 post a voluntary blood donation , and confirmed by the cdc .
the patient denied previous blood transfusions and never traveled to bolivia or any other endemic destinations in the americas . in 2012 ,
treatment with nifurtimox , 10 mg / kg orally daily , divided in three doses for 90 days as per cdc protocol , was provided .
his primary care physician has followed him on a regular basis , and to date the patient has remained without evidence of active clinical disease . the patients mother was born and resided in the city of concepcin , bolivia , until she was 18 years of age .
she moved to silver spring , maryland in 1982 where she had two uneventful pregnancies and deliveries in 1988 and 1990 , moving to miami five years later .
while in the united states , the mother never lived in sub - standard housing , rural or sub - urban areas , had contact with potential animal reservoirs , or received blood transfusions .
she had been a blood donor prior to the red - cross protocol including chagas disease screening since 2007 .
considering that the two sons were diagnosed with cd without a clear known source of infection , she was tested at the blood bank as per her sons request .
the initial blood bank serology was positive ( march 2011 ) and most recently confirmed by the cdc in april 2015 .
the capacity of parasites to invade placental cells , as well as its virulence and level of parasitemia in pregnant women , is critical in the maternal - fetal transmission .
parasitemia increases during the 2nd and 3rd trimesters of pregnancy and high maternal parasitemia are associated with congenital transmission .
indeed , transmission occurs in nearly 100% of pregnant women with reactivated infections , in about 50% of acute infection during pregnancy , and in roughly 5% of chronic infection in endemic countries , .
the cdc has confirmed twenty - eight cases have been locally transmitted from 1955 to 2015 .
vector human transmission in the united states is rare and is likely related to a lower vector transmission efficacy due to the delayed defecation of the triatomine insects and better housing conditions , .
although possible , vectorial transmission in our cases is extremely unlikely in view to the fact that the patients never lived in sub - standard conditions in the united states or were exposed to vectors and small animal reservoirs while traveling ( la paz city , bolivia , case 1 ) .
patients were born to an infected mother who was never screened for cd during her two pregnancies , despite a strong epidemiological history of exposure to t. cruzi in bolivia .
the epidemiology of cd is changing due to immigration from endemic areas of latin america . around 300,000 persons infected with t. cruzi
the national notifiable disease surveillance system ( nndss ) of the united states does not require the mandatory notification of cd to public health authorities , making it difficult to accurately evaluate local transmission .
few states ( massachusetts , arizona , texas and tennessee ) consider cd a notifiable disease .
public entities at the federal and state level need to support the expansion of the surveillance programs nationwide .
awareness of cd among physicians in the united states in particular primary care physicians , pediatricians , obstetricians and cardiologists is fairly low .
the limited knowledge of congenital t. cruzi transmission is reflected by the lack of screening of pregnant women at risk , as evidenced in the current report .
the identification of t. cruzi by xenodiagnosis cd and can be routinely used to accurately diagnose the disease in the acute phase . however , during the indeterminate or chronic phase , diagnosis is made by serological methods .
once a positive diagnosis has been confirmed , there are only two drugs available for treatment ( nifurtimox and benznidazole ) .
nifurtimox ( lampit , bayer ; a 2-nitrofuran ) is the only anti - t .
the drug , as well as benznidazole ( lafepe ; a 5-nitroimidazole available in latin america ) , is active in acute infections ( 8095% ) , and efficacy varies among the endemic areas probably due to differences in the in vivo susceptibility of the circulating parasite populations .
congenital cd response to treatment is close to a 100% cure and generally well tolerated when treatment is administered within the first year of life , , .
the efficacy of both drugs in the prevalent chronic phase of the disease is significantly lower and more variable , depending on the duration of the infection .
two recent studies that evaluated the efficacy of nifurtimox in chronic patients using quantitative t. cruzi pcr and a novel proteomic biomarker found that in 77.8% and 43.3% of treated patients the circulating parasite burden dropped below the limit of detection of the methods after 13 and 36 months , respectively , .
adverse effects are frequent , dose - related and reversible : they include anorexia , nausea , vomiting , gastric pain , insomnia , headache , vertigo , excitability , myalgia , arthralgia and convulsions ; peripheral polyneuritis can occur which may necessitate discontinuation of treatment .
the diagnosis and treatment of cd needs to be emphasized and should be included in routine laboratory tests of pregnancy among immigrant women from endemic countries .
all infants with congenital disease should be treated during the first twelve months due to the high cure rates and treatment tolerance .
Output:
| two brothers with congenitally - acquired chagas disease ( cd ) diagnosed during adulthood are reported .
the patients were born in the usa to a mother from bolivia who on subsequent assessment was found to be serologically positive for trypanosoma cruzi .
serologic screening of all pregnant women who migrated from countries with endemic cd is strongly recommended . |
PubmedSumm118639 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: cl4 mice ( 16 ) were bred and experiments were performed under home office licence and in accordance with the animals ( scientific procedures ) act , 1986 , uk .
haemagglutinin peptide ( iystvassl ) and control k - binding peptide ( cw3 peptide , rylkngketl ) were purchased from alta bioscience .
replication - defective human type 5 adenovirus vector ( ad70 - 3 ) was provided by j. gauldie ( mcmaster university , ontario , canada ) .
the anti - k antibody sf1 - 1.1.10 was provided by p. kourilsky ( pasteur institute , paris , france ) .
biotinylation of sf1 - 1.1.10 and igg2a was performed using the ez - link sulfo - nhs - lc - biotinylation kit ( pierce biotechnologies ) .
intracerebral antigen injections and intracerebroventricular liposome infusions were performed stereotaxically using a minimally invasive technique , as described previously ( 20 ) .
a sterile , finely drawn glass micropipette , the tip of which measured 210 m in diameter , was used to deliver antigen ( 0.5 g ha or cw3 , or 5 10 pfu ad70 - 3 ) in a volume of 0.5 l of pbs over a period of 1 min . to minimize reflux along the injection tract ,
the needle was left in place for 1 min before being slowly withdrawn over another minute .
injections contained a trace of autoclaved colanyl blue ( clariant ) to help with localization of the focal antigen deposit during subsequent tissue processing .
after perfusion and tissue processing , 10-m - thick coronal sections were used for indirect immunohistochemistry or double immunofluorescence as described previously for frozen and wax - embedded sections ( 20 ) .
primary antibodies were purchased from serotec ( cd3 , cd4 , cd8 , cd68 , mhci , mannose receptor , and thy1.1 ) , abcam ( granzyme b ) , novocastra ( ki67 ) , neomarkers ( 1-laminin ) , chemicon ( mbp and neun ) , sigma - aldrich ( cnpase and map2 ) , zymed laboratories ( app ) , and dakocytomation ( gfap ) . for antibodies raised in mouse ,
bright field and fluorescence images were captured on a leica light microscope using leicaqwin software and a leica tcs sp2 aobs confocal system , respectively .
cl4 cd8 t cells were purified by positive selection as described previously ( 18 ) .
cl4 mice were immunized with an intradermal injection of 100 l pbs / cfa ( 1:1 ) with or without 5 g ha . on day 5 , the animals received an intrastriatal injection of ha followed by perfusion 5 d later .
wild - type balb / c mice received an intrastriatal injection of ha or cw3 , and 4 h later they were injected i.v . with 3 or 30 million in vitro activated cl4 cd8 t cells in 200 l dmem .
cells were counted using a graticule under a high power objective ( 25 ) , and the density of cells was converted to a value per mm . in all cases , at least four lesion - center sections ( as shown by the co - injected blue dye ) from the same animal and several animals from each experimental group ( as denoted by number n ) were taken , and counts were averaged .
all the data were parametric , and therefore the two - tailed student 's t test for two independent samples was used throughout .
cl4 mice ( 16 ) were bred and experiments were performed under home office licence and in accordance with the animals ( scientific procedures ) act , 1986 , uk .
haemagglutinin peptide ( iystvassl ) and control k - binding peptide ( cw3 peptide , rylkngketl ) were purchased from alta bioscience .
replication - defective human type 5 adenovirus vector ( ad70 - 3 ) was provided by j. gauldie ( mcmaster university , ontario , canada ) .
the anti - k antibody sf1 - 1.1.10 was provided by p. kourilsky ( pasteur institute , paris , france ) .
biotinylation of sf1 - 1.1.10 and igg2a was performed using the ez - link sulfo - nhs - lc - biotinylation kit ( pierce biotechnologies ) .
intracerebral antigen injections and intracerebroventricular liposome infusions were performed stereotaxically using a minimally invasive technique , as described previously ( 20 ) .
a sterile , finely drawn glass micropipette , the tip of which measured 210 m in diameter , was used to deliver antigen ( 0.5 g ha or cw3 , or 5 10 pfu ad70 - 3 ) in a volume of 0.5 l of pbs over a period of 1 min . to minimize reflux along the injection tract ,
the needle was left in place for 1 min before being slowly withdrawn over another minute .
injections contained a trace of autoclaved colanyl blue ( clariant ) to help with localization of the focal antigen deposit during subsequent tissue processing .
after perfusion and tissue processing , 10-m - thick coronal sections were used for indirect immunohistochemistry or double immunofluorescence as described previously for frozen and wax - embedded sections ( 20 ) .
primary antibodies were purchased from serotec ( cd3 , cd4 , cd8 , cd68 , mhci , mannose receptor , and thy1.1 ) , abcam ( granzyme b ) , novocastra ( ki67 ) , neomarkers ( 1-laminin ) , chemicon ( mbp and neun ) , sigma - aldrich ( cnpase and map2 ) , zymed laboratories ( app ) , and dakocytomation ( gfap ) . for antibodies raised in mouse ,
bright field and fluorescence images were captured on a leica light microscope using leicaqwin software and a leica tcs sp2 aobs confocal system , respectively .
cl4 cd8 t cells were purified by positive selection as described previously ( 18 ) .
cl4 mice were immunized with an intradermal injection of 100 l pbs / cfa ( 1:1 ) with or without 5 g ha . on day 5 , the animals received an intrastriatal injection of ha followed by perfusion 5 d later .
wild - type balb / c mice received an intrastriatal injection of ha or cw3 , and 4 h later they were injected i.v . with 3 or 30 million in vitro activated cl4 cd8 t cells in 200 l dmem .
cells were counted using a graticule under a high power objective ( 25 ) , and the density of cells was converted to a value per mm . in all cases , at least four lesion - center sections ( as shown by the co - injected blue dye ) from the same animal and several animals from each experimental group ( as denoted by number n ) were taken , and counts were averaged .
all the data were parametric , and therefore the two - tailed student 's t test for two independent samples was used throughout .
Output:
| cd8 t cells are nature 's foremost defense in encephalitis and brain tumors .
antigen - specific cd8 t cells need to enter the brain to exert their beneficial effects . on the other hand , traffic of cd8 t cells
specific for neural antigen may trigger autoimmune diseases like multiple sclerosis .
t cell traffic into the central nervous system is thought to occur when activated t cells cross the blood - brain barrier ( bbb ) regardless of their antigen specificity , but studies have focused on cd4 t cells . here , we show that selective traffic of antigen - specific cd8 t cells into the brain occurs in vivo and is dependent on luminal expression of major histocompatibility complex ( mhc ) class i by cerebral endothelium .
after intracerebral antigen injection , using a minimally invasive technique , transgenic cd8 t cells only infiltrated the brain when and where their cognate antigen was present .
this was independent of antigen presentation by perivascular macrophages .
marked reduction of antigen - specific cd8 t cell infiltration was observed after intravenous injection of blocking anti
mhc class i antibody .
these results expose a hitherto unappreciated route by which cd8 t cells home onto their cognate antigen behind the bbb : luminal mhc class i antigen presentation by cerebral endothelium to circulating cd8 t cells .
this has implications for a variety of diseases in which antigen - specific cd8 t cell traffic into the brain is a beneficial or deleterious feature . |
PubmedSumm118640 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: staphylococcus aureus is a gram - positive bacterial pathogen that colonizes anterior nares and mucosal surfaces in humans and is responsible for causing a wide array of diseases from mild skin infections to life - threatening conditions such as bacteremia , pneumonia , and endocarditis [ 14 ] .
the emerging resistant strains of s. aureus exacerbate efforts to control or properly treat staphylococcal infections .
the host immune system responds to bacterial infections in a concerted manner to eliminate this pathogen .
this involves recruitment of polymorphonuclear leukocytes and macrophages to the site of infection and ingestion of invading bacteria .
uptake of bacteria triggers oxygen - dependent and oxygen - independent microbicidal pathways in the phagocytic cells .
the oxygen - dependent pathway generates superoxide anion ( o2 ) that serves as a precursor for additional reactive oxygen species ( ros ) such as hydrogen peroxide ( h2o2 ) , hydroxyl radical , singlet oxygen , hypochlorous acid ( hocl ) , and peroxynitrite [ 69 ] .
it produces antioxidant enzymes such as superoxide dismutase that converts superoxide anion to h2o2 , catalase that converts h2o2 to water and oxygen , and alkyl hydroperoxide reductases that detoxify h2o2 , peroxynitrites and hydroperoxides [ 10 , 11 ] .
in addition to their ability to protect from host 's oxidants , s. aureus infections impose oxidative stress in a host . during infection with a methicillin resistant s. aureus strain
nitric oxide ( no ) is a free radical synthesized by nitric oxide synthase .
certain gram - positive bacteria express homologs of nitric oxide synthases ( nos ) that have been extensively studied in eukaryotic species . in these species , nos - derived nitric oxide ( no )
is involved in vasodilation , neurotransmission , and host defense [ 7 , 13 , 14 ] , but the functions of bacterial nos are still being defined .
recent genome sequencing has revealed that nos - like protein exists in many bacteria including streptomyces ( stnos ) , deinococcus ( drnos ) , staphylococcus ( sanos ) , and bacillus ( bsnos ) species .
bacterial nos enzymes are homologous with the mammalian nos , but lack an associated nos reductase and n - terminal -hairpin hook that binds zn , the dihydroxypropyl side chain of h4b , and the adjacent subunit of the oxygenase dimer [ 1518 ] .
it has also been reported that in bacillus subtilis , no protects bacterial cells from reactive oxygen species .
in addition , the in vivo survival of bacillus anthracis was dependent on its own nos activity .
nos activity was also shown to protect from oxidative stress , and deletion of the gene encoding nos reduced the virulence of a methicillin resistant s. aureus . in this study ,
sanos - derived no was seen to be protective in a methicillin sensitive s. aureus from lethal oxidative stress conditions , suggesting its moderate role in stress tolerance .
all experiments were carried out using the methicillin sensitive s. aureus strain sh1000 ( wild - type ) , its isogenic sanos deletion mutant , and the mutant complemented with sanos in trans .
bacterial cultures were grown in tryptic soy broth / agar ( tsb / tsa ; becton dickinson ) at 37c in a shaking ( 220 rpm ) or static incubator . when needed ,
tetracycline ( 10 g ml ) and chloramphenicol ( 10 g ml ) were added to the growth medium .
plasmid dna was isolated using the qiaprep kit ( qiagen inc . ) ; chromosomal dna was isolated using a dnazol kit ( molecular research center ) from lysostaphin - treated s. aureus cells as per the manufacturer 's instructions .
oligonucleotide primers were obtained from sigma genosys . to construct a mutation in the sanos gene , primers p1 ( 5-acgaattctgctagcctttgttg-3 ) and p2 ( 5-ggatcccaaaataaacgaccaatgc-3 )
were used to amplify an 831 bp dna fragment using genomic dna from s. aureus strain sh1000 as the template .
this amplicon represents sanos left flanking fragment ( starting 207 nt downstream of the sanos start codon and going upstream ) .
another set of primers , p3 ( 5-ggatccattatctccaacattg-3 ) and p4 ( 5-tctagaatcagcctgaacgaaaaatcg-3 ) , was used to amplify an 850 bp dna fragment representing sanos right flanking fragment ( starting 120 nt upstream of the sanos stop codon and going downstream ) .
these two fragments were ligated together into vector ptz18r and a unique bamhi site was engineered between the ligated fragments . to the bamhi site of this fragment ( lacking most of the sanos gene ; 750
nt out of a total of 1074 nt of the sanos gene ) , a 2.2 kb tetracycline resistance cassette was cloned .
the resulting construct was used as a suicidal plasmid to transform s. aureus rn4220 cells by electroporation .
transformants were selected on tsa plates containing 10 g ml tetracycline that led to a single crossover event where the mutated sanos from the plasmid was integrated into the bacterial genome leaving the wild - type sanos intact .
these merodiploids were used to resolve the mutation in the sanos gene using a phage 80 transduction procedure as described previously [ 24 , 25 ] .
mutation in the sanos was verified by pcr . for genetic complementation of the sanos mutant , a 2.4
kb dna fragment was pcr amplified using primers p1 and p4 and s. aureus sh1000 genomic dna as template .
the amplicon represents a fragment starting from 624 nt upstream and spanning 730 nt downstream of the sanos gene that was cloned into the shuttle plasmid pcu1 and subsequently transferred to the sanos mutant of s. aureus strain sh1000 .
qrt - pcr assays were carried out as described using primers p5 ( atggtgctaaaatggcttggc ) and p6 ( gcttcgtcagtaacatctcttg ) to determine optimum expression of sanos during different stages of s. aureus growth in tsb .
bacterial cells were harvested from early- ( od600 = 0.6 ) , mid- ( od600 = 1.8 ) , late - exponential ( od600 = 3.0 ) , and stationary ( od600 = 4.2 ) phase cultures .
total rna extracted from these cells was used in qrt - pcr assays as described .
total protein was extracted from lysostaphin treated s. aureus cells grown to od600 = 0.6 as described previously .
the nos activity was determined using nos activity assay kit ( cayman chemical company ) and radioactive h arginine monohydrochloride as substrate ( amersham biosciences ) . for these studies , s. aureus cells from early exponential phase cultures
od600 = 0.6 were treated with 350 mm h2o2 for 30 min .
l - arginine serves as a substrate for the nitric oxide synthase in the production of no .
wild - type s. aureus cultures in tsb were added with l - arginine ( 1 mm final concentration ) at od600 = 0.5 and subsequently at od600 = 0.6 were stressed with 350 mm h2o2 to determine if the addition of l - arginine affected no production and the oxidative stress tolerance . additionally , the wild - type s. aureus cells were collected from cultures grown to od600 = 0.3 and were resuspended in similar volume of tsb containing 5 mm l - name ( tocris bioscience ) , an inhibitor of nos activity . at an od600 = 0.6 ,
these nos - inhibited cells were stressed with 350 mm h2o2 for 30 min and the surviving bacteria were counted . to further ascertain the role of nitric oxide in the protection of s. aureus cells ,
the sanos mutant cells at od600 = 0.5 were treated with 2.5 mm concentration of an no donor , sodium nitroprusside ( snp ) ( sigma ) . at od600 = 0.6 ,
these snp - treated cells were stressed with 350 mm h2o2 for 30 min , and the surviving bacteria were counted .
the promyelocytic hl-60 cells ( atcc ) were grown in iscove 's modified dulbecco 's medium ( imdm ) ( atcc ) with 20% fetal bovine serum ( fisher ) and were treated with 1.3% dmso ( fisher ) for 5 days to induce their differentiation into neutrophil - like cells [ 29 , 30 ] .
morphology of differentiated cells was confirmed by giemsa staining under inverted microscope . the oxidative burst inside neutrophil cells was determined by the reduction of nitroblue tetrazolium .
the differentiated neutrophils were used for phagocytic killing using a method described previously with slight modification . in brief , the neutrophils ( 1 10 ) were added with s. aureus cells ( 2.5 10 ) ( moi 1 : 2.5 ) in a 24-well plate .
the plate was centrifuged at 4000 rpm for 10 min and incubated in a co2 incubator at 37c for 1 h. the supernatant was gently aspirated and the neutrophils were lysed by the addition of imdm containing 0.025% triton x-100 .
the number of surviving bacteria was enumerated by making serial dilutions and plating of this lysate on tsa plate .
all results are reported as the mean sd of at least three independent experiments .
data were analyzed with dunnett 's method in one - way analysis of variance or with student - newman - keuls method in two - way analysis of variance using statistical analysis computer programs ( sigmaplot for windows , version 12.0 , systat software , inc . ) .
to investigate the role of the s. aureus nitric oxide synthase and no produced by this enzyme , the sanos gene was deleted and replaced with a tetracycline cassette by site - directed mutagenesis .
the deletion of sanos gene was confirmed by pcr ( figure 1 ) . in qrt - pcr assays , maximum expression of sanos in strain sh1000
the expression of sanos declined dramatically during the late stages of the bacterial growth and was least during the stationary phase ( table 1 ) . a higher bacterial no production was also noted during the early stages of macrophage infection by b. anthracis .
the determination of nos activity , based on the conversion of l - arginine to citrulline , indicated that sanos was functional and was able to use l - arginine as the substrate ( table 2 ) .
the level of citrulline in the sanos mutant was similar or below the background level ; a reaction mixture that contained only the l - arginine substrate and no protein extract was added to this reaction mixture ( table 2 ) .
the complementation of the sanos mutant with sanos gene on a high copy plasmid led to a significant increase in the nos activity in this complemented strain ( table 2 ) .
similar nos activities in these strains were also verified by measuring the nitrite and nitrate levels using griess reagent ( data not shown ) .
there was no change in the growth of the mutant strain and it was comparable to the growth of the wild - type s. aureus ( data not shown ) . under stress conditions such as salt ( 1.5 mm nacl ) and ph ( 6.0 or 8.5 ) ,
the growth rate of the sanos was comparable to the growth rate of the wild - type s. aureus ( data not shown ) .
also , in the presence of 1.1 mm h2o2 , the growth of the sanos mutant of s. aureus sh1000 was comparable to the wild - type strain ( data not shown ) .
however , it has been shown that the priming of the b. subtilis cells with nitric oxide for 5 sec leads to a significant increase in their resistance to the exposure of a much higher h2o2 concentration ( 370 mm ) . in qrt - pcr assays ,
maximum expression of sanos was determined in the cells from the early exponential phase ( od600 = 0.6 ) .
thus , cultures at this density were used in h2o2 susceptibility assays . when wild - type and the sanos mutant cells were treated with a lethal dose of 350 mm h2o2 ,
there were significantly more surviving wild - type bacteria ( > 1000-fold ) compared to the sanos mutant bacteria under identical experimental conditions ( figure 2(a ) ) .
addition of l - arginine is expected to increase the production of nitric oxide and thus is expected to also increase the resistance of s. aureus cells grown in the presence of l - arginine .
addition of l - arginine indeed increased the resistance of the wild - type s. aureus cells but caused no increase in the survival of the sanos mutant ( figure 2(a ) ) .
complementation of sanos mutant with the sanos gene on a plasmid partially restored the ability of these bacteria to survive h2o2 stress when it was grown with or without l - arginine ( figure 2(a ) ) . when the nos activity was inhibited in the wild - type s. aureus by the addition of l - name , a competitive inhibitor of the nos enzymatic activity
, it dramatically reduced the bacterial survival ( figure 2(b ) ) under oxidative stress .
in addition , when sodium nitroprusside ( an no donor ) was added to the sanos mutant cells , there was significant increase ( > 300-fold ) in the survival of the mutant bacteria when they were exposed to h2o2 ( figure 2(c ) ) .
these results , collectively , suggest the role of a functional nitric oxide synthase in the protection of s. aureus cells from oxidative stress conditions .
neutrophils are a critical component of innate immunity and are essential in controlling bacterial infections in a host .
experiments were carried out to determine if the lack of a functional nos decreased the survival of the s. aureus bacteria when it was allowed to interact with neutrophils . in these experiments , the sanos mutant showed significantly reduced survival compared to the wild - type s. aureus ( figure 3 ) .
these sanos mutant bacteria were also used to determine their survival compared to wild - type s. aureus in a murine intraperitoneal model as described previously [ 24 , 25 ] . however , there was no decrease in the survival of the sanos mutant when compared to the wild - type s. aureus bacteria ( data not shown ) .
the ability of the sanos mutant cells to make biofilms was also comparable to the wild - type s. aureus cells ( data not shown ) .
in recent years , the presence of nos has been viewed with great interest for its role in bacterial physiology and virulence .
presence of nos was determined to be a key factor in the defense of b. subtilis and b. anthracis from reactive oxygen species generated by the neutrophils and macrophages [ 19 , 20 ] .
we observed a slight reduction in catalase activity in the sanos mutant relative to its level in the wild - type s. aureus ( data not shown ) .
. a lower level of superoxide dismutase activity was determined in the sanos mutant of a methicillin resistant s. aureus .
the reduced catalase and superoxide dismutase activity levels might be the reasons of the reduced survival of the sanos mutant under oxidative stress .
lack of the ability of the s. aureus cells to produce no increased the susceptibility to reactive oxygen species and host antimicrobial peptides .
the level of the expression of the staphylococcal nos was induced by exposure to cell wall - active antibiotics and it was also determined to be a factor in conferring resistance to these antibiotics in a methicillin resistant s. aureus .
surprisingly , in that study , the lack of a functional nos increased the resistance of s. aureus to aminoglycosides .
infection with the mutant cells resulted in smaller abscess formation compared to the s. aureus cell with a functional nos suggesting its role in staphylococcal virulence . in our studies that utilized a methicillin sensitive s. aureus , there was no difference in the survival of the sanos mutant in a mouse .
there was also no appreciable difference in the survival or growth of the sanos mutant of s. aureus sh1000 under mild stress conditions .
the difference in the survival was only detected when the sanos mutant and the wild - type bacteria were exposed to a lethal dose of h2o2 .
the reduction in virulence of s. aureus subsequent to sanos deletion in the recent report can be attributed to strain differences ( methicillin - resistant versus methicillin - sensitive s. aureus ) and to a difference in the type of animal model used to study the virulence .
these strain differences are significant as host neutrophils respond differently when they are exposed to methicillin - resistant s. aureus compared to during infection with methicillin - sensitive s. aureus .
no production decreased in neutrophils in mice infected with vancomycin sensitive s. aureus and exposed to vancomycin but the decrease in neutrophilic no production was insignificant when the mice were infected with vancomycin resistant s. aureus and exposed to vancomycin . during the phagocytic process to control bacterial infections , the respiratory burst generates two very potent toxic substances , h2o2 and superoxide anions ( o2 ) .
a model has been proposed describing how bacterial no might be protective from the toxic action of these reactive oxygen species [ 19 , 20 ] .
it is suggested that the o2 fails to cross the bacterial cell wall and membrane and limits the production of peroxynitrites inside the bacterial cell from a reaction between bacterial no and phagocytic o2 .
although h2o2 can diffuse inside the bacterial cell , a higher bacterial catalase should degrade it to protect the bacterial cells from any damage .
considering the fact that the sanos was seen to be significant only during extreme conditions of stress and has a varied role in antibiotic stress tolerance and virulence , more studies need to be carried out to determine the significance of this enzyme in s. aureus .
Output:
| nitric oxide and its derivative peroxynitrites are generated by host defense system to control bacterial infection . however certain gram positive bacteria including staphylococcus aureus possess a gene encoding nitric oxide synthase ( sanos ) in their chromosome . in this study
it was determined that under normal growth conditions , expression of sanos was highest during early exponential phase of the bacterial growth . in oxidative stress studies ,
deletion of sanos led to increased susceptibility of the mutant cells compared to wild - type s. aureus .
while inhibition of sanos activity by the addition of l - name increased sensitivity of the wild - type s. aureus to oxidative stress , the addition of a nitric oxide donor , sodium nitroprusside , restored oxidative stress tolerance of the sanos mutant .
the sanos mutant also showed reduced survival after phagocytosis by pmn cells with respect to wild - type s. aureus . |
PubmedSumm118641 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: malaria is one of the most widespread parasitic diseases in the tropical and subtropical regions of the world and is transmitted by female anopheles mosquitoes .
fives species of malaria parasites infect humans : plasmodium falciparum ( p. falciparum ) , p. vivax , p. malariae , p. ovale , and p. knowlesi .
the most deadly form of malaria is p. falciparum , which has a shorter period of infection and more severe parasitemia . according to the latest report of the world health organization ( who ) in 2015 , a total of 95 countries and territories had ongoing malaria transmission with an estimated 3.2 billion people at risk of malaria .
also , there were an estimated 214 million new cases of malaria and 438000 deaths annually .
about 90% of all malaria deaths happen in the african region due to p. falciparum , especially among children younger than 5 years of age . during their life cycle ,
plasmodium parasites are dependent on 2 hosts : the sexual cycle in the anopheles mosquito as the main host and the asexual cycle in the human as the intermediate host . during a blood meal by the infected female anopheles mosquito ,
. then , sporozoites mature into tissue schizonts , which rupture and release merozoites ( liver stage ) . in this stage
, some species of plasmodium can form hypnozoites , which can remain hidden in the liver for many weeks or years .
thereafter , merozoites move into blood , where they infect the red blood cells and form trophozoites .
these red blood cells rupture and infect the healthy red blood cells . in this stage ,
if an anopheles mosquito bites an infected person , the sexual cycle of the parasite in the mosquito begins ( figure 1 ) .
the common symptoms of malaria include high fevers , chills , sweats , headaches , nausea and vomiting , diarrhea , body pain , and bloody stool .
also , malaria may cause severe anemia because of the loss of red blood cells . if not quickly treated , malaria can become severe and may cause coma and death . based on the different stages of the life cycle of the parasite
, there are a variety of drugs that affect these stages and exert their therapeutic effects .
for instance , quinine , chloroquine [ cq , 2 ] , amodiaquine [ aq , 3 ] and mefloquine [ mq , 4 ] are fast - acting and highly effective blood schizonticidal drugs with a quinoline scaffold against malaria parasites - mainly p. falciparum . in general , cq and aq are called 4-aminoquinolones which are the most important and widely used class of antimalarial drugs .
nonetheless , the development of drug resistance has restricted their use for malaria prophylaxis and treatment .
recently , researchers have synthesized new compounds based on the 4-aminoquinoline scaffold and evaluated their antimalarial activities .
the aim of this review article is introduction of new 4-aminoquinoline candidates ( cq and aq analogues ) with antiplasmodial activity against the cq - sensitive and cq - resistant strains of plasmodium , especially p. falciparum .
life cycle of the malaria parasite : humans and female anopheles mosquitoes are two hosts of malaria parasites . in humans ,
the parasites grow and multiply in the liver cells ( liver stage ) and then in the red blood cells ( blood stage ) . in mosquitoes ,
for many years , the bark of the cinchona tree was used to treat fever .
later years , its active ingredient , quinine , was isolated and identified as the oldest effective drug for malaria treatment .
quinine , as an alkaloid , is a fast - acting and highly effective blood schizonticidal drug against the species of human malaria , especially severe malaria .
quinine also has weak gametocide activity against p. vivax and p. malariae . however , there were concerns about the toxicity of quinine .
these analogues were inspired from the structure of the quinoline ring in quinine which is still used in the treatment of malaria ( figure 2 ) .
cq has been widely used since the1940s as the drug of choice for the treatment all types of malaria and has provided effective , affordable , and safe treatment for patients around the world . cq is more effective and safer than quinine as a blood schizonticidal drug , but it is not active against the liver stage and mature gametocytes .
today , the use of this drug has been restricted after widespread parasitic resistance to cq in different regions , which was led to a major health concern in malaria - endemic areas .
therefore , researchers focused on the discovery of alternative antimalarial drugs that could be effective against cq - resistant strains . as a result , other 4-aminoquinolines were developed as cq analogous .
aq , a mannich base 4-aminoquinoline , is a cq analogue with a mechanism of action similar to cq and is effective against cq - resistant p. falciparum strains . nevertheless , there is a cross - resistance between aq and cq .
this is noticeable that aq is associated with agranulocytosis and hepatotoxicity as side effects after its long - term administration ; therefore , the clinical use of aq has been severely limited .
mq , which has a similar structure to quinine , is recommended for malaria prophylaxis and acute therapy in most malarious areas with cq - resistant strains .
the use of mq was confirmed by the center for disease control and prevention ( cdc ) .
mq is a potent blood schizonticidal drug with a long half - life , although the toxicity of this drug has limited its usage . today
the success of cq in this group was due to its excellent clinical efficacy , low toxicity , easy usage , and cost - effective synthesis .
unfortunately , in today s world , one of the most serious problems in the treatment , control , and elimination of malaria is drug resistance against affordable , safe , and readily available drugs such as cq and pyrimethamine / sulfadoxine . due to this serious health problem ,
further research on new synthetic analogues containing the quinoline ring has revealed that these compounds can be suitable alternative agents for old antimalarial drugs .
considering the importance of review articles , in this paper , we introduce a number of new cq and aq analogues containing the 4-aminoquinolone ring .
accordingly , the parasite enters the host s red blood cell and digests hemoglobin ( hb ) in its acidic food vacuole ( fv ) as the dominant source of nutrition .
hb is a multi - subunit protein with an iron - containing heme group found in erythrocytes .
after hb digestion in the fv of the parasite , hb is degraded to amino acids and heme ( ferriprotoporphyrin ) as a toxic by - product .
the parasite needs these amino acids for its growth , and several malarial protease enzymes are involved in this degradation process .
plasmodium parasites do not have any enzymes to metabolize toxic heme , which is responsible for the parasite s death .
nonetheless , the malaria parasite has developed a special process for the detoxification of heme .
for this purpose , the malaria parasite converts heme to hemozoin as an insoluble crystalline form ( malaria pigment ) by heme polymerization .
hemozoin is not toxic for the parasite , and its formation is an essential mechanism for the detoxification and survival of the parasite ( figure 3 ) .
generally , small molecules with a 4-aminoquinoline moiety such as cq and its analogues present antimalarial activity through the prevention of hemozoin formation which is resulted to the parasite s death .
the fv has a lysosomal structure with an approximate ph of 55.2 , whereas cq is a weak base with pka of 8.1 and pka of 10.2 which penetrates through the parasite s membrane in its unprotonated form .
in this situation , cq is protonated and accumulated in the acidic fv of plasmodium species , especially p. falciparum and is trapped in its acidic form ( protonated form ) .
cq and its analogues can inhibit the formation of hemozoin and increase the intracellular heme ( figure 3 ) .
in other words , it is inferred that cq and its analogues somehow intervene with the parasite - feeding process .
cq is transferred to the food vacuole ( fv ) of the parasite and trapped in its acidic form .
these factors included frequent travels to malarious areas , uncontrolled treatment regimens with cq , and finally the feeding of mosquitoes from different hosts .
the weak accumulation of cq into the fv of the parasite is the most important mechanism of resistance , accord with mutations in transporter proteins such as the p. falciparum cq resistance transporter ( pfcrt ) and multi - drug resistant protein-1 ( pfmdr1 ) which have located in the parasite s fv membrane .
consequently , the decrease in drug accumulation is responsible for the loss of antiplasmodial activity .
it has been reported that pfcrt mutation at amino acid 76 reduces the cq uptake into the fv ( figure 4 ) .
in other words , this mutation is resulted to cq efflux out of the acidic fv , or the transporter ( pfcrt ) acts as a channel and allows the exit of cq from the fv of the parasite .
the mutation in pfmdr1 also reduces the transport capacity of the drug ( figure 4 ) .
mutations in transporter proteins ( pfcrt and pfmdr1 ) decrease cq accumulation in the parasite s food vacuole .
cq is swiftly metabolized into metabolites , n - desethyl chloroquine ( dcq ) and n - bis - desethyl chloroquine ( bdcq ) , after oral or intravenous administration by the liver and kidney .
the major active metabolite of cq is dcq with activity against cq - sensitive strains , but its activity has decreased against cq - resistant strains ( figure 5 ) .
aq is metabolized to deaq as its major active metabolite and toxic metabolite ( aqqi ) .
aq is extensively metabolized in the liver , and its major metabolite is desethyl amodiaquine ( deaq ) .
the metabolite is obtained from the n - deethylation of aq by cyp2c8 ( figure 5 ) .
while the formation of this metabolite is fast , its elimination is very slow with a half - life of 100 hours .
aq is more potent than its metabolite , whereas the concentration of deaq in blood is higher than aq .
amodiaquine quinone - imine ( aqqi ) is another metabolite of aq that is obtained in the presence of cytochrome p450 as a toxic metabolite .
it is noteworthy that the high dose or long - term use of aq is led to the depletion of glutathione levels and eventually , liver toxicity .
the metabolite ( aqqi ) is also susceptible to nucleophilic attack by enzymes in addition to glutathione in the liver .
indeed , aqqi reacts with key human enzymes that have thiol groups and forms adducts with these enzymes .
the spread of cq resistance is a serious problem in malaria prevention and treatment that was first reported during the 1950s .
this effective drug was the treatment of choice in many geographical areas , although with the development of cq resistance , the combination of pyrimethamine / sulfadoxine was used for 20 years instead of cq .
studies in this field demonstrated that , after a few years , sensitivity to cq was recovered with limitation of mutation such as the deletion of pfcrt t76 mutation in malawi after 8 years of its discontinuation .
the presence of the flat heteroaromatic ring for connection to heme and the diethyl amino group for accumulation in the fv are the necessary factors in order to antimalarial activity ( figure 6 ) . nowadays , due to the importance of cq , researchers have focused on the design of new quinoline - based antimalarial compounds . in these derivatives ,
the quinoline ring has been often preserved and the pentamine chain has been replaced by other substituents .
important parts of cq containing the quinoline ring , the pentamidine chain and amino alkyl head . accordingly
aq-13 is one of these analogues with a diamino - alkyl side chain shorter than the alkyl chain of cq .
the compound has pharmacokinetic and mechanism of action , similar to those of cq .
in vivo studies showed that the n - deethylation of aq-13 is led to specific changes in lipophilicity and increase the cross - resistance of this compound even more that of cq .
the synthetic analogues of cq containing modified side chain with antimalarial activity . due to the influence of metal complexes in many pharmaceutical compounds ,
many of these compounds were more effective than cq in both in vitro and in vivo tests .
currently , ferroquine [ fq , 6 ] has been introduced as a metal complex of cq and a candidate for clinical studies ( figure 7 ) . in this compound
, the ferrocene group alone does not have particular antimalarial activity ; however , due to the tendency of the parasite to iron , the confrontation of the parasite with the compound increases .
this compound is active against the cq - resistant strains of p. falciparum and p. vivax .
piperaquine is a dimer analogue of cq that was widely used in the 1970s1980s for the treatment of cq - resistant p. falciparum strains in china ( figure 7 ) .
the compound has two of the 4-aminoquinoline groups that have been join to each other by a dipiperazine - propyl linker .
the appropriate activity of piperaquine against the resistant parasites is attributed to its bulky structure , which prevents its connection to the pfcrt site .
also , the compound is trapped powerfully into the fv of the parasite with its positive charges and prevented the heme detoxification system in the malaria parasite .
the investigation of the pharmacokinetic properties of piperaquine demonstrated high lipid - solubility , long elimination half - life , good bioavailability , and fast clearance .
these advantages , in addition to low cost and good tolerability , was resulted to the selection of the drug for children .
today , the prevalence of p. falciparum resistance to piperaquine has reduced monotherapy . nevertheless , therapy with piperaquine and dihydroartemisinin ( dha )
the only problem with this combination therapy is the long half - life of piperaquine ( 16.5 d ) and the short half - life of dha ( 1/2 h ) .
recently , a combination of piperaquine with arterolane has been entered into phase clinical trials .
this combination drug acts through 2 different mechanisms to overcome drug resistance . considering the importance of combination therapy ,
research groups have focused on synthetic hybrid molecules containing 2 pharmacophores with a covalent linkage .
for example , trioxaquine analogues exhibited strong activity against cq and pyrimethamine - resistant strains in a single dose .
in these hybrid molecules , drug - drug adverse interactions are minimized . among the analogues of trioxaquine
, compounds sar116242 and du1302 were selected as antimalarial candidates ( figure 7 ) .
the excellent antimalarial activity of the hybrid [ sar116242 , 8 ] against the cq - sensitive and cq - resistant strains of p. falciparum is attributed to the dual mechanism of action including hemozoin inhibition and heme alkylation .
this compound is a racemic mixture , and investigations have demonstrated that both diastereoisomers have similar activity in vitro against plasmodium . also , the compound with the cyclohexyl linker has acceptable metabolic stability .
this is a mannich base 4-aminoquinoline with a similar mechanism to that of cq which was first introduced as a cq alternative .
hence , aq was used against cq - resistant strains in p. falciparum parasites for prophylaxis and treatment .
but its application was limited due to serious adverse effects such as agranulocytosis and hepatotoxicity with its long - term use . in addition
is also attributed to mutation in the transporter pfcrt . in 1990 , who recommended combination therapy of aq especially with artemisinin derivatives for the treatment of uncomplicated malaria .
artemisinins are short - acting antimalarial drugs and their combination therapy with long - acting drugs is led to a delay in development of p. falciparum drug resistance .
these compounds have a cq - like moiety and a resistance reversal - like moiety .
rcqs interact with different types of transporters ( pfcrts ) and solve the problem of cq - resistance in p. falciparum with inhibition hemozoin formation . in these compounds ,
the length of the linker between quinoline and nitrogen is an important factor to overcome cq - resistance .
also , the hybridization of cq with primaquine ( pq ) through different linkers displayed good activity against the different stages of p. falciparum .
the hybrid molecule is active against the liver stage and the blood stage of the different strains of p. falciparum as well as the maturation of gametocytes . on the other hand ,
this hybrid compound present synergistic effect between pq and cq moieties which is responsible for increased activity .
cq analogues [ 13 - 14 ] with bulky side chains showed excellent activity against the cq - resistant strain w2 .
these compounds do not have base moiety but inhibit hemozoin formation , similar to cq .
previously , it was assumed that base side chain is a necessary part for antiplasmodial activity .
the compound exhibited superior in vitro activity in comparison with cq and notable in vivo suppression assay .
the compound is more potent than cq with a dual mechanism of action , inhibition of hemozoin formation , and inhibition of falcipain-2 .
n - cinnamoylated cq analogue , as a dual - stage antimalarial lead compound , displayed potent activity against the blood stage ( cq - resistant w2 and cq - sensitive 3d7 strains ) and the liver stage p. falciparum .
, the compound also had in vivo activity against the blood - stage rodent malaria parasites .
a new analogue of cq , containing a side chain with a bulky base head , showed excellent activity against the cq - resistant ( w2 ) strain of p. falciparum . in this compound
, the spacer length between the bulky head and the quinolone ring plays an important role in antimalarial activity .
aq is a potent antimalarial drug but side effects of hepatotoxicity and agranulocytosis have limited its use . due to the suitable activity of aq in malaria treatment , researchers focused on the design and synthesis of new analogues of aq to solve its toxicity problem ( figure 8) . in this
regard , fluoro - amodiaquine [ faq , 17 ] obtained to change the hydroxy group of the phenyl ring with a fluorine atom at the 4-position of aq .
fluorine is an important agent in medicinal chemistry , and researchers usually use fluorine in the drug design to block the metabolic sites .
therefore , faq is not metabolized to the toxic quinone - imine metabolite and keeps significant antimalarial activity against cq - resistant strains .
tebuquine [ tq , 18 ] is another analogue of aq which prepared by the substitution of 4-chloro phenyl moiety at the 5-position of the hydroxyaniline side chain of aq .
this compound was more active than cq and aq in both in vitro and in vivo studies .
the toxic metabolite of aqqi is formed after a long - term administration of tq , similar to aq .
subsequently , a synthetic compound with 3,5- di(methylpyrrolidine ) substituents , was designed with steric hindrance around the hydroxyl group at the 4-position . as a result
unfortunately , the compounds have long half - lives , which is led to increased toxicity and spread of resistance .
other non - toxic analogue of aq [ 20 - 21 ] obtained to interchange the hydroxyl group at the 4-position of aq with dialkyl amino methylene at the 3-position . with this change , the toxic quinone - imine metabolite is not formed .
in addition , the compounds exhibited potent antimalarial activity against cq- sensitive and cq - resistant strains .
isoquine [ isq , 20 ] is an isomer of aq with a diethyl amino methylene substituent at the 4-position which showed the strongest in vitro activity against p. falciparum and good in vivo activity after oral administration against p. yoelii in comparison with aq .
the metabolic studies in rats confirmed the absence of glutathione metabolites in the bile , but they also presented severe hepatic first - pass metabolism , leading to the production of deethylated metabolites .
in fact , iso has less toxicity than aq because of excretion glucuronide metabolites instead of glutathione conjugates .
gsk369796 was synthesized as an n - tert - butyl analogue of isq to modify its low efficacy problem .
dealkylation of this compound is difficult because of steric hindrance around the n - dialkyl group . as a result
pre - clinical evaluation of this compound confirmed better pharmacodynamic and pharmacokinetic profile than that of isq .
the advantages of gsk369796 include similar potency to aq , low toxicity , and easy metabolism in comparison with aq . with all of the listed advantages ,
the compound is not acceptable because of the lack of a suitable dose in compared with cq .
mono - mannich base [ isotebuquine , 22 ] showed ( ic50 = 0.3 ng / ml against d6 , 0.4 ng / ml against w2 , and 1.78 ng / ml against tm91c235 ) the best activity against p. falciparum .
a toxicity study in a murine monocyte - like macrophage presented low toxicity in comparison with tq .
the thompson test in infected mice with p. berghei by oral administration did not show any significant activity , which may be the result of poor oral bioavailability . in regard to the importance of halogen atoms in the drug design , 4-fluoro - n - tert - butyl amodiaquine [ faq-4 , 23 ]
was prepared with the displacement of the fluorine atom with 4- hydroxy and 3-n- tert - butyl with 3-n - diethyl in aq to block the metabolism site ( n - dealkylating ) , which is resulted to the formation of the toxic metabolite of aqqi .
this compound , with a suitable oral bioavailability and a good safety profile , is undergoing pre - clinical studies .
the benzoxazole analogue of aq showed excellent activity against two cq - resistant strains ( k1 and w2 ) of p. falciparum with ic50 values of 8 and 2.2 nm , respectively .
the low cytotoxicity of this compound against l6 ( rat myoblast ) cells and its high selectivity indices present a suitable alternative for aq .
the high potency to this analogue is related to the presence of an amine group .
additionally , the benzoxazole substituent attached to the 4-amino-7-chloroquinoline ring block the toxic metabolite formation , without loss of antiplasmodial activity .
the modification of isq as a non - toxic aq analogue was led to the synthesis of a compound with a diisopropylamine side chain .
this compound presented good antimalarial activity with a mic value of 10 g / ml . however , the compound do not have activity better than cq .
an in vitro evaluation of the compound against the k1 strain of p. falciparum showed comparable activity with isq and better activity than aq with an ic50 value of 1.4 nm . nonetheless , the toxicity of this compound is higher than aq , with a narrow therapeutic window .
no - aq derivatives [ 27 and 28 ] were synthesized and displayed excellent in vitro activity against cq - sensitive and cq - resistant strains of p. falciparum .
these compounds have either furoxan or nitrooxy moiety as a nitric oxide ( no)-donor group and are able to dilate a rat aorta strip with an no - dependent mechanism .
these hybrid molecules [ 27 and 28 ] displayed in vivo antiplasmodial activity similar to aq . a new aq analogue [ pm6577 , 29 ] with a morpholino group at 4-position and a pyrrolidino group at 3-position aniline ring showed antiplasmodial activity comparable to aq when tested on the f32 and k1 strains of p. falciparum .
moreover , the cytotoxicity of this compound was evaluated on two human cell lines ( a diploid embryonic lung and a neuroblastoma cell line ) and showed low toxicity .
the physiochemical ( adme ) properties and permeability profile of the compound is also evaluated in the pre - clinical phase .
the spread of resistance to current antimalarial drugs have prompted investigators and pharmaceutical companies to focus on the development of new antimalarial drug . meanwhile , different organizations such as the bill and melinda gates foundation ( bmgf ) and medicines for malaria venture ( mmv ) support malaria elimination programs around the world .
many new compounds have been synthesized by research groups and evaluated for antimalarial activity . due to the appropriate efficacy of antimalarial drugs with a 4-aminoquinolone scaffold such as cq and aq ,
new analogues have been synthesized based on this scaffold and evaluated in both in vitro and in vivo tests against various cq - sensitive and cq - resistance strains of the malaria parasite , especially p. falciparum .
this review article introduces new series of cq analogues to overcome resistance and aq analogues to reduce toxicity .
all compounds have the active nucleus of the 7-chloro-4-aminoquinoline and present antimalarial activity against cq - resistant strains .
therefore , further research on these analogues should be continued to achieve a new , efficient , cheap , and safe antimalarial drug with a 4-aminoquinoline structure as the next- generation of cq / aq analogues in clinical development .
Output:
| antimalarial drugs with the 4-aminoquinoline scaffold such as the important drugs , chloroquine ( cq ) and amodiaquine ( aq ) , have been used to prevent and treat malaria for many years .
the importance of these drugs is related to their simple usage , high efficacy , affordability , and cost - effectiveness of their synthesis . in recent years , with the spread of parasite resistance to cq and cross - resistance to its other analogues have decreased their consumption in many geographical areas . on the other hand
, aq is an effective antimalarial drug which its usage has been restricted due to hepatic and hematological toxicities . the significance of the quinoline ring at quinoline - based antimalarial drugs has prompted research centers and pharmaceutical companies to focus on the design and synthesis of new analogues of these drugs , especially cq and aq analogues .
accordingly , various derivatives have been synthesized and evaluated in vitro and in vivo against the resistant strains of the malaria parasite to solve the problem of drug resistance .
also , the pharmacokinetic properties of these compounds have been evaluated to augment their efficacy and diminish their toxicity .
some of these analogues are currently in clinical and preclinical development .
consequently , the recent researches showed yet 4-aminoquinoline scaffold is active moiety in new compounds with antiplasmodial activity .
hence , the aim of this review article is to introduce of the novel synthetic analogues of cq and aq , which may constitute the next generation of antimalarial drugs with the 4-aminoquinoline scaffold . |
PubmedSumm118642 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: air pollution is known to have an adverse effect on different sectors of the economy , including public health .
it is therefore relevant to include in cost - benefit analyses of mitigation projects an assessment of the potential savings in healthcare resources due to a reduction in morbidity and mortality .
the relationship between exposure to air pollution , the disease burden , and healthcare costs can not be determined precisely .
air pollution impacts negatively on health ; mitigating air pollution could potentially result in health benefits .
a recent literature review identified several studies of the relative changes in incidence and mortality associated with changes in air pollution .
the review specifically identified the connection between an increase in fine particulate matter ( pm2.5 ) and the following four diseases : coronary heart disease ( chd ) , stroke , chronic obstructive pulmonary disease ( copd ) , and lung cancer . a review linked to the present study that explored the literature relating to healthcare cost savings of a reduction in air pollution identified six nonsource - specific studies on the impact of particulate matter on healthcare costs [ 27 ] .
these studies were conducted in other countries and dealt with air pollution in different circumstances .
pm10 is associated with less severe health effects than is pm2.5 . in the present study
the objective was to develop a method to assess the potential effects of air pollution mitigation on healthcare costs .
we focused on the effects of changes in the level of pm2.5 and developed a method to assess the potential benefits for the danish healthcare sector from a reduction in air pollution .
as a case , we assumed a 10 g / m decrease in the annual mean level of pm2.5 . compared with data from the danish national air pollution monitoring programme , this corresponds to a reduction of 51% and 76% of present levels in copenhagen at street level and rooftop urban background , respectively .
since most individuals are exposed to some levels of air pollution , it is not feasible to differentiate between individuals who are exposed to certain levels of air pollution . therefore , this study used an indirect method of identifying the exposed individuals ( as opposed to nonexposed ) . by applying assumptions about the relative risks of new diseases ( incidence ) we attributed a change in disease incidence to a change in air pollution exposure . in denmark , easy access to administrative health registers provides excellent conditions for register - based research .
the use of individual civil registration numbers enables researchers to make connections between registers containing information about individuals ' use of healthcare resources as well as demographics and other social variables .
for this study , we used individual encrypted data on healthcare utilisation , sociodemographics , education , migration , and death on the entire danish adult population .
these data were supplied and hosted by statistics denmark . to describe healthcare utilisation , we used data from the danish national health service register , the danish national patient register , and the danish national prescription registry .
information on sociodemographics , education , migration , and death was retrieved from the danish civil registration system and from registers about level of education , labour market affiliation , personal income and transfer payments , and causes of death .
we also used data from the dancos cohort , which includes individuals who participated in the danish nationally representative health interview surveys .
the cohort provided self - reported information on health status and smoking habits , among other things . to simplify the analyses , we excluded individuals who emigrated from denmark after the baseline year .
healthcare costs in the primary healthcare sector were defined as the reimbursement to the patient by public health insurance ( in most cases 100% of average costs ) .
the diagnosis - related groups ( drg ) tariff , defined as the average cost per admission , was used as the cost of admissions . the ambulatory grouping system ( dags ) tariffs defining the average cost per visit were used to cost outpatient or emergency room visits in the secondary healthcare sector . neither the drg nor dags tariffs included contributions to fixed costs .
to value the cost of prescription medicine , the full sales price was used , including both the patient 's payment and the reimbursed element .
costs were discounted at a 3% discount rate and adjusted to similar pricing levels ( fixed at 2006 pricing levels ) . for women aged 5079 and exposed to a 10 g / m increase in the annual mean level of pm2.5 , the relative risk of being incident with chd and stroke was assumed at 1.21 and 1.35 , respectively .
based on findings on mortality related to particulate emissions , for example , pope et al . , we assumed that the relative risk for cardiovascular events in men was lower than for women .
tentatively , therefore , we assumed the relative risk ( rr ) to be half that of the increased risk for women , that is , for stroke the rr for men was 1.175 and for coronary heart disease 1.105 .
for both men and women aged over 30 , we assumed that the rr of copd for a 10 g / m increase in the annual mean level of pm2.5 was 1.14 .
for lung cancer , we used the rr of mortality as an approximation for incidence .
the rr of lung cancer mortality per 10 g / m increase in the annual mean level of pm2.5 was assumed at 1.14 .
we assumed that , by inverting the rr , we would achieve an expression for the reduction in incidence due to a 10 g / m decline in the annual mean level of pm2.5 for chd , stroke , copd , and lung cancer , enabling us to calculate a number of saved cases .
, the costs associated with a particular disease can be determined as the difference between average healthcare costs of diseased individuals and a comparable nondiseased control group , thus covering all contacts with the healthcare system regardless of the reason for the contact . in the analysis
, we matched the cases ( individuals with one of the four diseases ) with a set of controls ( individuals without any of the four diseases ) by use of propensity scoring .
this method aims to identify individuals who are similar with respect to a predetermined set of sociodemographic characteristics .
we assumed that the cost difference for these two groups accounts for the average attributable cost of the disease .
we multiplied the average attributable cost with the number of saved cases following a reduction in air pollution to arrive at an expression for healthcare cost savings from a 10 g / m decline in the annual mean level of pm2.5 .
individuals were identified as cases if they had at least one inpatient admission , outpatient visit , or emergency room visit with a relevant primary diagnosis .
we defined our diagnoses according to the icd10 classification codes : chd = i2025 , stroke = i6069 , copd = j4144 , and lung cancer = c33 - 34 .
the time of incidence was defined as the date of the first hospital contact due to disease ( including death ) .
individuals with the disease who were in contact with primary care facilities only could not be identified .
we applied a washout period of 20 years to ensure that the identification of cases was based on the first occurrence of the diagnosis .
1997 was considered as the baseline year as it was the first year where detailed data on healthcare cost was available in the registers .
we required a minimum number of 25 cases for the estimates to be considered to have sufficient statistical power .
where our requirement was not met , we extended the baseline to a longer period .
, hospitalisation for copd patients most often occurs at a relatively late stage of the disease .
therefore , we were not able to identify the true date of onset of copd from registers .
as a pragmatic solution to this , we introduced a lag - time of nine years and assumed that true incidence of copd was nine years prior to the first hospitalisation . in this way
, we identified a cohort of cases with their first hospitalisation in 2006 and followed them retrospectively from 1997 to 2005 .
we defined this cohort as the prehospitalisation cohort and used it in the estimation of attributable healthcare costs related to the years prior to the first hospitalisation .
regarding healthcare utilisation after hospitalisation , we used the same method as for the other three analysed diseases .
we stratified all analyses by gender and age in five - year intervals ( 5054 ,
, 7579 , 80 + ) . for chd and stroke the rr change associated with an increase in the air pollution could only be identified for individuals in the 5079 age range .
we assumed that the rr for older age groups was identical to that of younger age groups . for lung cancer we excluded individuals older than 79 because the mortality by the fifth year would have resulted in fewer than 25 cases .
the attributable costs of chronic diseases range in time from the onset of disease to the time of death .
therefore , we applied the longest time horizon allowed by the data . for chd and stroke ,
the follow - up period was 10 years , for copd 19 years , and for lung cancer eight years .
in the baseline year , we determined the propensity score for the entire population at risk using logistic regression .
the propensity score expresses the likelihood of being incident during the year depending on cohabiting status , educational level , socioeconomic status , age , gender , and comorbidity .
for comorbidity , we used an adjusted charlson index , which did not include scores achieved from the analysed diseases .
we included all theoretically relevant variables that were accessible from registers regardless of their significance in the logistic regression .
the variable x in ( 1 ) included age , cohabitation status , education , socioeconomic status , and comorbidity .
cases were matched 1 : 5 with controls using nearest neighbour matching , where each case was matched with the five individuals closest to the case , measured on propensity score .
this allowed us to identify a cohort of controls that was similar to cases ( measured by the likelihood of being incident ) but without having the disease .
the variable x in ( 1 ) included age , cohabitation status , education , socioeconomic status , and comorbidity .
cases were matched 1 : 5 with controls using nearest neighbour matching , where each case was matched with the five individuals closest to the case , measured on propensity score .
this allowed us to identify a cohort of controls that was similar to cases ( measured by the likelihood of being incident ) but without having the disease .
since we had detailed data on all individuals in all years , we could apply the method developed by lin et al .
, dividing the entire study period into smaller periods and multiplying the kaplan - meier estimator for the probability of surviving to the start of each interval with an appropriate estimator of the average cost over the interval , given survival to the start of the interval . from this point on , we therefore separated regression of cases from that of controls .
in the first part of the two - part method we calculated the share of individuals with positive healthcare costs , ct .
we use ct for adjustment of the healthcare costs , which are calculated for individuals with positive healthcare costs , thus achieving an expression of the average healthcare costs for all individuals . given positive healthcare demand , we suggested the average cost for individuals alive at the beginning of the year to be estimated assuming a log - link and a lognormal distribution in a generalised linear mixed model with a categorical variable , year , indicating the year ( after incidence ) , and an individual random effects term , z , as explanatory variables .
equation 2
two part
part ii:(2)e(healthcare costs positive demand ) = +tyear+z , where t=(01t ) ,
where t is the time horizon . with the mixed model
, we addressed heterogeneity and with the generalised form we addressed the log - normality of healthcare costs .
we were particularly interested in the parameter estimates of and , which in combination express the log of healthcare costs .
part ii:(2)e(healthcare costs positive demand ) = +tyear+z , where t=(01t ) ,
where t is the time horizon . with the mixed model
, we addressed heterogeneity and with the generalised form we addressed the log - normality of healthcare costs .
we were particularly interested in the parameter estimates of and , which in combination express the log of healthcare costs . however ,
since the log of healthcare costs was of little informative value , a retransformation was needed . in order to compensate for retransformation bias
equation 3
duan smearing estimator:(3)sm= 1nee ,
where e is error term from the regression of healthcare costs and
duan smearing estimator:(3)sm= 1nee ,
where e is error term from the regression of healthcare costs and n is the number of individuals in the cohort .
once we knew ( from ( 2 ) and ( 3 ) ) the average healthcare cost given positive demand , the two - part method led to a multiplication of these findings with the share of individuals with positive demand , ct , in order to achieve the expected healthcare cost .
equation 4
expected healthcare cost for individuals surviving to the start of year t:(4)hc(t)=ct+e2+tsm .
subsequently , we calculated the survival at the end of each time period ( or , equivalently , the beginning of the following time period ) .
subsequently , we calculated the survival at the end of each time period ( or , equivalently , the beginning of the following time period ) .
equation 5
kaplan - meier survival estimate:(5)s^(t)=i=0tnidini ,
where ni is number of survivors up to time period i , and di is the number of deaths in time period i.
kaplan - meier survival estimate:(5)s^(t)=i=0tnidini ,
where ni is number of survivors up to time period i , and di is the number of deaths in time period i. by weighing average costs for individuals surviving to the start of period t with the survival to the start of period t ( or , equivalently , end of period t 1 ) and subsequently summing over the entire time horizon , t , we achieved an expression of the attributable costs of the given disease .
equation 6
npv healthcare costs per case attributable to the air - pollution - related disease:(6)npv=t=0thcp(t)s^p(t1)hcc(t)s^c(t1)(1+)t .
subscripts p and c denote group assignment ( patient or control), is the discounting factor and
( 7)s^p , c(t1)=1 , for t=0 .
npv healthcare costs per case attributable to the air - pollution - related disease:(6)npv=t=0thcp(t)s^p(t1)hcc(t)s^c(t1)(1+)t .
subscripts p and c denote group assignment ( patient or control), is the discounting factor and
( 7)s^p , c(t1)=1 , for t=0 .
the expression in the numerator can be interpreted as the expected healthcare cost attributable to the pollution related disease in year t. all terms were aggregated over time in order to achieve the total net present value of expected healthcare cost attributable to the disease .
as noted previously , we assumed that the rr could be inverted to give an incidence after a 10 g / m decline in the annual mean level of pm2.5 .
thus , we could calculate the decline in the incidence .
equation 7
number of saved cases due to a 10 g / m decline in the annual mean level of pm2.5:(8)cases saved=(11rr)incidence before .
having achieved the total net present value in ( 8) and the number of saved cases in ( 9 ) , we multiplied these two in order to achieve the benefit from mitigation in terms of healthcare cost savings .
number of saved cases due to a 10 g / m decline in the annual mean level of pm2.5:(8)cases saved=(11rr)incidence before .
having achieved the total net present value in ( 8) and the number of saved cases in ( 9 ) , we multiplied these two in order to achieve the benefit from mitigation in terms of healthcare cost savings .
equation 8
healthcare cost savings per 100,000 inhabitants related to a 10 g / m decline in annual mean pm2.5:(9)healthcare cost savings = npvcases saved .
healthcare cost savings per 100,000 inhabitants related to a 10 g / m decline in annual mean pm2.5:(9)healthcare cost savings = npvcases saved .
table 1 shows the characteristics of the analysis populations including t - tests for equality of means . in the 1997 national patient register
, we identified 20,083 , 13,632 , and 9,058 incident cases of chd , stroke , and copd , respectively . in 19971999 , we identified 10,200 incident cases of lung cancer and in 2006 we identified 7,712 incident cases of copd .
42% to 53% were female , and this was highest for stroke and copd , and 49% to 61% of the populations were married .
the average charlson score was lowest for the cardiopulmonary diseases , ranging from 0.3 to 0.4 , while the average charlson score for lung cancer cases and controls was about 1.2 .
more than 80% of cases and controls were outside the labour market ( i.e. , either retired or on early retirement ) .
for those still in the labour market , the majority were blue collar workers .
therefore , the survival in the retrospective part of the copd analysis was assumed at 100% .
hence , we chose to expand the baseline for lung cancer in order to increase the size of the cohort .
thus , we pooled incident cases and their controls in the years 19971999 for analyses of lung cancer
.
table 2 illustrates incidences per 100,000 inhabitants and attributable healthcare costs per episode .
the incidence of lung cancer was an average of incidences in 19971999 and the incidence of copd was an average of 1997 and 2006 .
as it is not within the scope of this study to provide a detailed analysis of the above table , it suffices to state that the incidence rates are within the expected range and in accordance with common knowledge of the epidemics of the diseases .
the negative attributable costs in the oldest age groups with chd and lung cancer can be explained by a poor survival prognosis compared to their controls .
table 3 shows the healthcare cost savings per 100,000 inhabitants of a 10 g / m decline in the annual mean level of pm2.5 for 10 , 10 , 19 , and 8 year - time horizons for chd , stroke , copd , and lung cancer , respectively , and a total for the danish population aged 50 + .
a formal comparison of the estimated cost data for the different diseases requires an equal time horizon .
therefore , it is only relevant to compare the healthcare costs of cardiovascular diseases ( chd and stroke ) .
stroke had a much higher potential of healthcare cost savings from air pollution mitigation compared to chd .
this is partly explained by the attributable healthcare costs per case , which are positive for any stroke age group and higher than those of chd for any age / gender group , whereas it is negative for the oldest age groups of chd .
it is also partly due to the fact that the incidence of stroke is more responsive to changes in air pollution ( i.e. , has higher rrs ) than is chd .
tables 48 show sensitivity analyses of the total cost ( corresponding to the last column of table 3 ) when different model assumptions have been applied . in the base case
, we have used a modified charlson index to control for comorbidity in the matching algorithm . in this first sensitivity analysis , we have excluded comorbidity from the matching algorithm in order to test the sensitivity of the base case results to comorbidity
table 4 shows us that potential healthcare cost savings increase marginally when excluding comorbidity from the matching .
this indicates that comorbidity contributes in the propensity score of being incident with the four analysed diseases and by taking it out of the matching algorithm we select a set of controls that are healthier than the controls selected for the base case . both from a danish and a worldwide perspective
, radical changes are expected to the composition of the population over the coming 50 years .
all other things being equal , this will impact on potential healthcare cost savings . table 5 shows a one - way sensitivity analysis based on population projections from statistics denmark .
estimates of the total healthcare cost savings were lower for the diseases , except for stroke , for which there was a close to zero change .
the reduced healthcare cost savings is a result of a shift of the population towards a higher fraction of the older age groups and relatively smaller attributable healthcare costs in the older age groups .
it is a matter for discussion as to whether or not inclusion of savings to healthcare costs due to the premature death of case individuals is unethical .
we have included these in the base case while some may argue that , by doing so , one favours disease and air pollution through potential healthcare cost savings due to increased mortality among cases . in order to shed light on the magnitude of this potential source of bias
, we have calculated a one - way sensitivity analysis replacing s^c with s^p in the calculation of healthcare costs ( 6 ) .
the results of the sensitivity analysis are that healthcare costs beyond the death of the cases are eliminated , giving a positive gain in the potential of reducing the levels of pm2.5 . in absolute figures ,
these are considerable changes in all four diseases , representing the fact that premature mortality is a major factor in these diseases ( even when comorbidity is taken into account ) .
table 7 shows a one - way sensitivity analysis of the healthcare costs of copd associated with particulate emissions with updated survival on the prospective part . for survival in the year of the first hospitalisation
, we used the 2006 cohort survival and adjusted the survival of the prospective part of the analysis on the basis of this .
the sensitivity analysis resulted in very small changes in the estimates of total healthcare cost savings compared to the base case .
our estimates of rrs taken from the literature were based on cohorts studied many years ago and under different circumstances ; therefore , the rrs may not be representative for our case .
additionally , a mitigation of more than 50% of current air pollution levels may be difficult to achieve , especially considering that current levels are already below eu limit values
. it may be more realistic to consider scenarios with smaller changes in air pollution .
both these concerns relate to the rr and a sensitivity analysis of changes in rr therefore seemed evident .
table 8 shows a scenario where mitigation is only 5 g / m ( corresponding to half the rr ) . in this scenario ,
healthcare costs of all four diseases decrease by 43% to 48% , indicating that the elasticity of the healthcare cost savings with respect to the rr is close to one in our model .
we have devised a method to calculate the number of saved cases associated with a 10 g / m decline in the annual mean level of pm2.5 ( using rrs found in the literature ) .
we multiplied these numbers of cases with the average healthcare cost per episode of pollution related disease in order to achieve the healthcare cost savings attributable to a 10 g / m decline in the annual mean level of pm2.5 . using this method
however , the applied method is challenged by various factors . the achievement of the objective to estimate potential benefits in terms of reduced healthcare costs
rests on the assumption that all health effects of air pollution have been captured by the selection of the four diseases .
more diseases than selected for this study were found to be related to air pollution .
however , the indirect method we used to identify exposed individuals requires that we only use diseases with significantly increased rrs of incidence or mortality , hence the selection of the four diseases . by not taking into account all potential benefits in terms of health effects ,
an important strength of the analysis is its basis in real - life individual data obtained from routine administrative registers .
this enabled a much more detailed analysis and the combination of a number of very strong and well - proven methods and principles .
the cost - benefit framework is useful for analysing the full effects of mitigating air pollution .
in such a framework , the costs make up the actual costs of implementing mitigation interventions .
the benefits would be in the form of healthcare cost savings , productivity gains and the value of increased utility of reduced pollution .
the advantage of analysing in a cost - benefit framework is that it is intuitive and yields a single numeric ( positive or negative ) describing the net benefit of the mitigation effort .
the results of our analysis may therefore be used as input in a cost - benefit framework .
however , it is important to note that mitigating air pollution reduces incidence in diseases with high mortality , thereby increasing the average remaining life expectancy and hence the time span in which positive healthcare costs can be sustained .
combining this result with the productivity gains and the value of the increased utility of reduced pollution would give us the total benefits of an intervention , which reduces annual mean levels of pm2.5 by 10 g / m .
they may therefore differ substantially from healthcare costs of pollution - related diseases in countries with different organisational healthcare sector and cost structures .
we believe , however , that the method in itself is fully applicable to cost - benefit analyses in other countries . we know
that smoking , for instance , is a high - risk factor for the diseases analysed .
we explored the opportunity of matching with the inclusion of an index of smoking probability derived from a logistic regression from a subsample of the population .
the controls identified by this approach had almost identical healthcare costs compared to controls identified without the smoking probability .
therefore , we abandoned this approach . in the selection of controls for each disease , we excluded those individuals who became incident with the disease within the observation period .
this may bias the estimates of healthcare cost for controls , since the control population may be too healthy .
however , it was not possible to include them in the model using the method selected for this study . by including the individuals known to develop the disease
a series of studies [ 2527 ] discusses the issue of control selection . in our matching
, we found that chd and stroke cases were slightly older than controls and lung cancer cases had higher comorbidity than controls .
however , the absolute differences in age and comorbidity were relatively small and the significance is probably an indication that age did not contribute much to the propensity to be incident with chd or stroke ( already stratifying by five - year intervals ) and that comorbidity did not contribute much to the propensity of being incident with lung cancer . the studies on which we based our assumptions of rrs ( table 3 ) might have been based on other levels of air pollution and in other populations .
application of these rrs for denmark therefore relies heavily on the assumption that the rr is identical for other levels of air pollution .
no evidence of a nonlinear relationship ( within the ranges of pm pollution encountered in europe ) exists and for that reason a linear relationship is assumed .
it was not possible to establish the rrs of incidence of lung cancer associated with the outdoor concentration of pm2.5 .
thus , we used the rrs of mortality as an approximation for those of incidence .
this is not likely to induce much bias , since the prognosis of surviving once diagnosed with lung cancer is very poor .
we were challenged by left censoring in that some cases may have died prior to hospitalisation . however , by including information from the causes of death register , we believe that we captured the majority of cases .
cases particularly subject to left censoring are likely to be the mild cases that did not need hospitalisation and did not have the disease registered as cause of death .
it was not possible to identify the date of onset of disease using register - based analysis . by using the first hospital contact ( or time of death ) to identify time of onset of disease , our analyses were subject to left truncation .
cases will always have had a period of time with the disease prior to the first hospital contact .
we believed that the gravity of this error was largest for copd , which is known to have a long period prior to hospitalisation . by using a nine - year prehospitalisation period for copd cases ,
, we believed that the error obtained from not including a pre - hospitalisation period was negligible .
we therefore truncated the follow - up period of lung cancer to eight years to ensure sufficient statistical strength .
furthermore , we excluded individuals older than 79 years of age from the analysis of lung cancer . by truncating the follow - up period and excluding certain age groups
, we disregarded an element of the costs in estimating the healthcare cost savings for lung cancer . whether total healthcare cost savings would have been higher or lower depends on mortality and the level of healthcare costs of cases relative to controls in the years beyond the truncated period .
this also applies to chd , stroke , and copd . in accordance with the method used to define disease incidence and for reasons of limitations in data availability
, our analyses were limited to 10 , 10 , 19 , and eight years for chd , stroke , copd , and lung cancer , respectively .
as previously noted , an extension of the time horizon may reduce or increase healthcare cost savings depending on mortality and healthcare costs of cases relative to controls . analysing healthcare costs of two cohorts of copd patients and controls with different time of incidence
informed us that survival and ( initial ) healthcare cost patterns had changed from 1997 to 2006 .
the 1997 cohort experienced lower survival rates and lower initial healthcare costs compared to the 2006 cohort .
to our knowledge , no previous study has used the combination of lin 's approach , attributable cost computation and register - based data to arrive at an expression of healthcare costs associated with a given exposure , in this case , air pollution . in the present study , we succeeded in achieving our objective of developing a method for assessment of the benefits of mitigating air pollution in terms of healthcare cost savings , and applying it to the danish case with fine particle matter .
we found that there was a potential benefit in the form of reduced healthcare costs related to mitigation .
Output:
| objective .
the aim of this study was to develop a method to assess the potential effects of air pollution mitigation on healthcare costs and to apply this method to assess the potential savings related to a reduction in fine particle matter in denmark .
methods .
the effects of air pollution on health were used to identify exposed individuals ( i.e. , cases ) .
coronary heart disease , stroke , chronic obstructive pulmonary disease , and lung cancer were considered to be associated with air pollution .
we used propensity score matching , two - part estimation , and lin 's method to estimate healthcare costs .
subsequently , we multiplied the number of saved cases due to mitigation with the healthcare costs to arrive to an expression for healthcare cost savings . results .
the potential cost saving in the healthcare system arising from a modelled reduction in air pollution was estimated at 0.12.6 million per 100,000 inhabitants for the four diseases .
conclusion .
we have illustrated an application of a method to assess the potential changes in healthcare costs due to a reduction in air pollution .
the method relies on a large volume of administrative data and combines a number of established methods for epidemiological analysis . |
PubmedSumm118643 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: twenty to thirty percent of patients who have a transient ischemic attack or cerebral infarction have severe stenosis or occlusion of the extracranial internal carotid artery ( ica ) .
one is carotid endarterectomy ( cea ) , which is considered as the first choice in most patients due to the advantage of fewer complications , lower mortality , and lower expenses .
the major complications of cea include cerebral ischemia ( due to hypoperfusion and dropped embolus ) and cerebral hyperperfusion , both of which can result in intracranial hemorrhage and cognitive impairment .
the intracranial hemorrhage and cognitive impairment are mainly caused by cerebral hemodynamic changes [ 57 ] .
monitoring cerebral hemodynamics during surgery is important in cea because cerebral hemodynamics change during cea .
electroencephalogram and somatosensory evoked potential ( ssep ) allow identification of already significant cerebral ischemia and can indirectly reflect the cerebral hemodynamics [ 911 ] .
micro - vascular doppler ultrasonography ( mdu ) is the other intraoperative monitoring method for cerebral hemodynamics , which can measure the blood flow velocity directly .
perfusion computed tomography ( pct ) has recently become a useful tool for evaluation of cerebral perfusion .
the potential of pct to provide immediate information about cerebral perfusion during the performance of cea means it could be a useful intraoperative monitoring method in clinical practice .
this study aimed to evaluate the changes in pct parameters in cea , and to discuss the clinical use of intraoperative pct in cea .
between march 2012 and february 2013 , 16 patients with moderate or severe carotid stenosis combined with cea in our department were recruited in the present study ( table 1 ) .
patients inclusion criteria were : 1 ) the severity of the stenosis of the symptomatic carotid artery must be greater than 50% and 2 ) the severity of the stenosis of the asymptomatic carotid artery must be greater than 70% .
exclusion criteria were : intracranial artery occlusion , cerebral hemorrhage or fresh cerebral infarction within 2 weeks , stenosis location over the mandibular angle , presence of contraindications to contrast ( e.g. , renal failure , hyperthyroidism , and contrast material allergy ) , and patients not medically fit for surgery .
a 40-multislice ct scanner ( somatom sensation open sliding gantry , siemens medical solutions , germany ) with a sliding gantry and an 82-cm bore diameter was installed on rails mounted into the floor of the operating room .
a radiolucent , adjustable , flexible operating table with a carbon table plate ( trumpf , ditzingen , germany ) where the patient s head is fixed in a radiolucent headclamp ( mayfield integra , usa ) was used to maintain the scanning position .
this allowed the patient to move back automatically to the previous position when the scanning was performed again . a motor injection pump ( acist , usa )
after general anesthesia the patient was positioned on the operating table according to the surgery .
a collision check between the gantry and operating table was performed , and then the height of the bed was stored in memory . after connecting the motor injector pump to a median cubital vein catheter , pct scanning was performed ( i.e. , preoperative pct ) . connecting the electrodes to the head , the cea was performed .
the data of ssep and mdu and time of temporary clamping were recorded before clamping the ica and after closing the wound in the ica .
after the surgeon satisfied with the cea , all metal instruments were removed from the scanned area , a sterile drape was placed over the patient , and pct scanning was performed again ( i.e. , intraoperative pct ) .
then , the additional drape was removed , and the surgical procedure was resumed . a scout ct for planning of the scan range from the orbitomeatal line to the vertex
this was followed by pct scanning with 80 kv and 100 mas at the level of the basal ganglia for a period of 40 s. there was a 5-s delay after a bolus injection of 40 ml contrast agent ( ultravist 300 , 300 mg of iodine per milliliter ) .
then , a 40-ml saline flush was performed at 7 ml / s by using a motor injection pump , and pct scanning was started .
pct data were transferred to a pct workstation and were analyzed using the standard , vendor - provided software .
color - coded parameter maps of cerebral blood flow ( cbf ) , cerebral blood volume ( cbv ) , and time to peak ( ttp ) were also generated . to quantify changes in perfusion parameters before and during cea , the slab closest to the level of the basal ganglia on the pretreatment perfusion ct
scan was matched to the corresponding slab at the same level after treatment . when regions of interest ( rois ) , including middle cerebral artery ( mca ) territory and anterior communicating artery ( aca ) territory in the hemisphere were manually drawn on each slab , the mirrored rois in contralateral hemisphere
the absolute pct parameter values , including cbf ( expressed in milliliters per 100 milliliters of tissue per minute ) , cbv ( expressed in milliliters per 100 milliliters of tissue ) , and ttp ( expressed in milliliters per 100 milliliters of tissue ) in the operated side and contralateral , side were calculated .
relative pct parameters , including relative cbf ( rcbf ) , relative cbv ( rcbv ) , and relative ttp ( rttp ) , were calculated .
the two - tailed paired t test was used to compare the absolute pct parameter values in the operated side with those in the contralateral side separately , before and during cea .
then we compared the relative and absolute pct parameter values before cea with those during cea .
the sensitivity of pct , ssep , and mdu for evaluation of the cerebral perfusion was compared .
the criteria for ssep changes included the amplitude decreasing by more than 50% or latent period delaying more than 10% compared with baseline , which was confirmed before temporary ica clamping .
the criterion for mdu changes was the blood flow increasing or decreasing more than 10% compared with that before temporary ica clamping .
all pct scanning was performed by the same experienced radiology technologist , the pct data processing was done by a neuro - radiology technologist and a neurosurgeon , and the ssep and mdu were performed by an experienced electrophysiology technologist .
between march 2012 and february 2013 , 16 patients with moderate or severe carotid stenosis combined with cea in our department were recruited in the present study ( table 1 ) .
patients inclusion criteria were : 1 ) the severity of the stenosis of the symptomatic carotid artery must be greater than 50% and 2 ) the severity of the stenosis of the asymptomatic carotid artery must be greater than 70% .
exclusion criteria were : intracranial artery occlusion , cerebral hemorrhage or fresh cerebral infarction within 2 weeks , stenosis location over the mandibular angle , presence of contraindications to contrast ( e.g. , renal failure , hyperthyroidism , and contrast material allergy ) , and patients not medically fit for surgery .
a 40-multislice ct scanner ( somatom sensation open sliding gantry , siemens medical solutions , germany ) with a sliding gantry and an 82-cm bore diameter was installed on rails mounted into the floor of the operating room .
a radiolucent , adjustable , flexible operating table with a carbon table plate ( trumpf , ditzingen , germany ) where the patient s head is fixed in a radiolucent headclamp ( mayfield integra , usa ) was used to maintain the scanning position .
this allowed the patient to move back automatically to the previous position when the scanning was performed again . a motor injection pump ( acist , usa )
after general anesthesia the patient was positioned on the operating table according to the surgery . a collision check between the gantry and operating table was performed , and then the height of the bed was stored in memory . after connecting the motor injector pump to a median cubital vein catheter , pct scanning was performed ( i.e. , preoperative pct ) . connecting the electrodes to the head , the cea was performed .
the data of ssep and mdu and time of temporary clamping were recorded before clamping the ica and after closing the wound in the ica . after the surgeon satisfied with the cea , all metal instruments were removed from the scanned area , a sterile drape was placed over the patient , and pct scanning was performed again ( i.e. , intraoperative pct ) .
a scout ct for planning of the scan range from the orbitomeatal line to the vertex was acquired first .
this was followed by pct scanning with 80 kv and 100 mas at the level of the basal ganglia for a period of 40 s. there was a 5-s delay after a bolus injection of 40 ml contrast agent ( ultravist 300 , 300 mg of iodine per milliliter ) .
then , a 40-ml saline flush was performed at 7 ml / s by using a motor injection pump , and pct scanning was started .
pct data were transferred to a pct workstation and were analyzed using the standard , vendor - provided software .
color - coded parameter maps of cerebral blood flow ( cbf ) , cerebral blood volume ( cbv ) , and time to peak ( ttp ) were also generated . to quantify changes in perfusion parameters before and during cea , the slab closest to the level of the basal ganglia on the pretreatment perfusion ct scan was matched to the corresponding slab at the same level after treatment . when regions of interest ( rois ) , including middle cerebral artery ( mca ) territory and anterior communicating artery ( aca ) territory in the hemisphere were manually drawn on each slab , the mirrored rois in contralateral hemisphere
from each roi , the absolute pct parameter values , including cbf ( expressed in milliliters per 100 milliliters of tissue per minute ) , cbv ( expressed in milliliters per 100 milliliters of tissue ) , and ttp ( expressed in milliliters per 100 milliliters of tissue ) in the operated side and contralateral , side were calculated .
relative pct parameters , including relative cbf ( rcbf ) , relative cbv ( rcbv ) , and relative ttp ( rttp ) , were calculated .
the two - tailed paired t test was used to compare the absolute pct parameter values in the operated side with those in the contralateral side separately , before and during cea .
then we compared the relative and absolute pct parameter values before cea with those during cea .
the sensitivity of pct , ssep , and mdu for evaluation of the cerebral perfusion was compared .
the criteria for ssep changes included the amplitude decreasing by more than 50% or latent period delaying more than 10% compared with baseline , which was confirmed before temporary ica clamping .
the criterion for mdu changes was the blood flow increasing or decreasing more than 10% compared with that before temporary ica clamping .
all pct scanning was performed by the same experienced radiology technologist , the pct data processing was done by a neuro - radiology technologist and a neurosurgeon , and the ssep and mdu were performed by an experienced electrophysiology technologist .
compared to the absolute pct parameters in the operated side and contralateral side , the ttp in the operated side was increased significantly ( p<0.05 ) , whereas no difference in the cbf and cbv was found ( p>0.05 ) before cea in the mca territory . during cea ,
the increases in cbf and cbv and the decreases in ttp in the operated side were significant ( p<0.05 , table 2 ) . in the aca territory , all the absolute pct parameters had no significant changes ( p>0.05 , table 3 ) .
comparison of relative pct parameters before cea with those during cea revealed that the rcbf and rcbv were significantly increased and the rttp was significantly decreased in the mca territory ( p<0.05 ) , but no significant difference was detected in the aca territory ( p>0.05 , table 4 ) . in all 16 patients ,
pct parameters were improved , ssep was normal , and mdu was abnormal . in 3 patients , cbf
the mean time of temporal clamping was ( 27.565.26 ) min ( range , 1641 min ) .
none of the 16 patients had complications related to cea or the iodine contrast agent .
compared to the absolute pct parameters in the operated side and contralateral side , the ttp in the operated side was increased significantly ( p<0.05 ) , whereas no difference in the cbf and cbv was found ( p>0.05 ) before cea in the mca territory . during cea ,
the increases in cbf and cbv and the decreases in ttp in the operated side were significant ( p<0.05 , table 2 ) . in the aca territory , all the absolute pct parameters had no significant changes ( p>0.05 , table 3 ) .
comparison of relative pct parameters before cea with those during cea revealed that the rcbf and rcbv were significantly increased and the rttp was significantly decreased in the mca territory ( p<0.05 ) , but no significant difference was detected in the aca territory ( p>0.05 , table 4 ) .
in all 16 patients , pct parameters were improved , ssep was normal , and mdu was abnormal . in 3 patients , cbf increased by more than 70% after cea ( figure 1 ) .
the mean time of temporal clamping was ( 27.565.26 ) min ( range , 1641 min ) .
none of the 16 patients had complications related to cea or the iodine contrast agent .
pct was performed at the selected level with the help of a bolus injection of contrast agent , and the pct parameters obtained from time - density curve analysis were used to evaluate the brain perfusion .
compared to the other methods of perfusion imaging , such as positron emission tomography , single - photon emission computed tomography , xenon ct , and perfusion - weighted imaging , pct was shown to have advantages of simplicity , short acquisition time , and providing a high - quality image . therefore , pct is widely used to diagnose acute cerebral ischemic stroke , to access delayed ischemia in patients with subarachnoid hemorrhage , to measure reserve capacity in patients with carotid occlusive disease using acetazolamide , to evaluate the effect of endovascular treatment and extracranial - intracranial bypass surgery , to predict hyperperfusion after surgery , and to diagnose and classify brain tumors .
pct can provide quantitative information about brain perfusion status according to the cbf , cbv , and ttp .
however , the absolute pct parameters are easily subject to high intersubject variation and influenced by physiologic parameters , and frequently do not reflect true brain perfusion .
first , all the pct maps and rois were generated by the same experienced neuroradiologic technologist and neurosurgeon to minimize interoperator variability .
second , the transverse section was chosen through the level of the basal ganglia because this level contains representative territories supplied by the anterior , middle , and posterior cerebral arteries ; therefore , the rois were easy to select .
third , hand - drawn rois over the cortical gray matter of the expected territory of mca and aca were created , with care not to involve substantial parts of the cerebral white matter .
fifth , relative pct parameters were used to avoid influence of intraoperative anesthesia and blood pressure fluctuation . in the present study , 2 rois
none of the absolute or relative pct parameters changed significantly before or during cea in the aca territory .
first , the aca territory in the basal ganglia was so small that variation would easily be generated .
reported that the mca territory showed the least measurement variability compared with the aca territory .
secondly , unilateral carotid stenosis was well compensated from the anterior communicating artery . in the mca territory ,
statistical analysis showed that only the ttp in the operated side increased significantly , compared to the absolute pct parameters in the operated side and contralateral side before cea , as in the results reported by kmena .
when carotid stenosis develops , the cerebral hemodynamics change and result in a prolonged ttp at first .
therefore , the ttp is a sensitive parameter for detection of cerebral hypoperfusion . during the cea , all the pct parameters , including cbf , cbv , and ttp , in the operated side changed
this is not completely in concordance with the literature . when plaques are removed during cea , blood flow in the carotid artery are restored quickly , and the cerebral hemodynamics noticeably change in a short time .
however , other studies comparing pct parameters were done at 1 week or even longer after surgery . in the present study , the significant change found in rcbf , rcbv , and rttp during cea , in comparison with before cea ,
however , duan et al . reported that the rcbf and rttp changed significantly but the rcbv had no significant changes at 1 week after carotid stenting of unilateral symptomatic carotid artery .
second , the time points of investigation of brain perfusion were different ; our study investigates brain perfusion at 1 h after surgery , but other studies used later time points .
third , cbv , which reflects the vascular volume of arterial , capillary , and venous compartments in rois , is a complex physiological parameter and the vasodilatory response of these different vessels is variable .
since cea began to be used for treatment for carotid stenosis in 1950s , the effectiveness had been confirmed through more than 50 years of development and testing .
however , neurologic complications of cea due to cerebral hemodynamic changes during and after surgery occur in up to 5% of patients .
therefore , it was very important to get accurate and immediate information about brain perfusion during cea .
ssep is sensitive to the cerebral ischemia , but it may show false - negative results and influence by anesthetics .
mdu , which had been widely used in cerebral aneurysm surgery , can obtain the blood floor velocity and detect vascular stenoses as early as possible .
however , it had some inherent limitations , including inability to evaluate the distal collateral flow and provide information about cerebral circulatory .
in addition , intraoperative mr imaging can provide information about perfusion status of brain , but it is not widely used in clinical practice due to high expense and time required . to the best of our knowledge ,
first , intraoperative pct can provide immediate information about brain perfusion to help guide surgical therapy .
sanford et al . described using of pct to evaluate the effectiveness of ica stent placement in a patient with symptomatic transient ischemic attacks caused by tandem stenoses of ica and mca .
intraoperative pct revealed a marked improvement in mean transit time and cbf in the operated hemisphere after treating the proximal supraclinoid ica stenosis . considering the increased risks associated with mca stent implantation , and the improvements in cerebral perfusion , the surgeon decided to terminate treatment of the mca stenosis
in the present study , the time of intraoperative pct scanning procedure was approximately 10 min , including 2 to 3 min for preparation , 5 min for analysis of pct data , and 2 to 3 min for resuming surgery .
therefore , the surgical strategy could be quickly changed if cerebral hemodynamic abnormalities were observed . secondly ,
compared quantitative perfusion parameters in operated side with those in contralateral side , and compared those before and during cea , cerebral hemodynamic changes would be identified .
mdu indicated blood flow changed obviously . therefore , the accuracy of pct was superior to ssep and mdu in evaluation of brain perfusion .
thirdly , intraoperative pct could predict cerebral hyperperfusion during cea , which was defined as cbf increase of more than 100% compared with preoperative values in the operated side .
although none of the patients had cerebral hyperperfusion in the present study , the incidences of cerebral hyperperfusion after cea and cerebral hemorrhage caused by cerebral hyperperfusion were 12.5% and 0.37% , respectively , according to the literature .
chang et al . reported that cbv index and ttp index were effective tools for screening cerebral hyperperfusion .
suggested that patients with a prolonged dmtt of more than 3 s should be closely monitored for evidence of hyperperfusion after undergoing carotid stenting .
therefore , the sensitivity and specificity of pct were much better than ssep . in the present study , 3 patients had a cbf increase of more than 70% as measured by pct .
fourth , intraoperative routine ct scan , performed before the pct scan , revealed no cerebral hemorrhage .
this study was limited in a number of ways that need to be addressed in future research .
third , when the roi was selected , compensation of anterior communicating artery and posterior communicating artery was not taken into account .
fourth , pct scanning was performed only at the level of the basal ganglia , not the total brain .
fifth , this study analyzed brain perfusion during surgery and lacked long - term follow - up data .
finally , data analysis may be affected by the incomplete symmetry of space due to posture requirements during cea , such as head spins and cervical extension .
relative pct parameters , including rcbf , rcbv , and rttp , are sensitive indicators for detecting early cerebral hemodynamic changes during cea .
Output:
| backgroundthis study aimed to evaluate the changes in perfusion computed tomography ( pct ) parameters in carotid endarterectomy ( cea ) , and to discuss the use of intraoperative pct in cea.material/methodssixteen patients with carotid stenosis who also underwent cea with intraoperative ct were recruited in this study .
we calculated quantitative data on cerebral blood flow ( cbf ) , cerebral blood volume ( cbv ) , time to peak ( ttp ) , and the relative parameter values , including relative cbf ( rcbf ) , relative cbv ( rcbv ) , and relative ttp ( rttp ) .
the role of pct was assessed and compared to conventional monitoring methods.resultsthere were no significant differences in any of the parameters in the anterior cerebral artery ( aca ) territory ( p>0.05 ) . in the middle cerebral artery ( mca ) territory , the cbf and cbv increased and ttp decreased in the operated side during cea ; the rcbf and rcbv increased and the rttp decreased significantly ( p<0.05 ) . in 16 patients ,
ct parameters were improved , ssep was normal , and mdu was abnormal . in 3 patients , cbf
increased by more than 70% during cea .
relative pct parameters are sensitive indicators for detecting early cerebral hemodynamic changes during cea .
cerebral hemodynamics changed significantly in the mca territory during cea.conclusionsintraoperative pct could be an important adjuvant monitoring method in cea . |
PubmedSumm118644 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
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the input is a biomedical literature
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the output is the summary of an input biomedical literature in six sentences
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Input: paraquat ( pq ) is a herbicide that preferentially accumulates in the lung and exerts its cytotoxic effects via the generation of reactive oxygen species ( ros ) [ 13 ] .
many studies have focused on increasing the antioxidant status in the lung to protect against pq injury using various antioxidants , including antioxidant enzymes ( e.g. , sod ) , vitamins ( e.g. , ascorbic acid , -tocopherol ) , and low - molecular - weight thiol - containing antioxidants ( e.g. , glutathione ( gsh ) , n - acetylcysteine ( nac ) ) but the outcomes from such treatments are limited or without success [ 211 ] . the failure of these antioxidants to seriously modify the toxicity of the herbicide has been attributed mostly to their inability to cross cell membrane barriers and/or to their rapid clearance from cells [ 3 , 4 , 6 , 7 , 10 , 11 ] . in recent years , it has been demonstrated that the encapsulation of antioxidants in liposomes improves their therapeutic potential against oxidant - induced lung damage , including pq pulmonary toxicity , because liposomes facilitate intracellular delivery and prolong the retention time of entrapped agents inside the cell [ 3 , 6 , 1215 ] .
hydrophilic molecules can be encapsulated in the aqueous spaces , and lipophilic molecules can be incorporated into the lipid bilayers .
liposomes , in addition to their use as artificial membrane systems , are used for the selective delivery of antioxidants and other therapeutic drugs to different tissues in sufficient concentrations to be effective in ameliorating tissue injuries . the relative ease in incorporating hydrophilic and lipophilic therapeutic agents into liposomes , the possibility of directly delivering liposomes to an accessible body site , such as the lung , and the relative nonimmunogenicity and low toxicity of liposomes
have rendered the liposomal system highly attractive for drug delivery [ 3 , 12 , 16 ] . in the present study , we compared the effectiveness of conventional nac and liposomal - nac ( l - nac ) against pq - induced cytotoxicity and examined the mechanism(s ) by which these antioxidant formulations conferred their cytoprotection .
n - acetylcysteine is a low - molecular - weight thiol - containing antioxidant with free radical - scavenging properties [ 3 , 17 , 18 ] attributed to the nucleophilicity and redox interactions of its thiol group [ 17 , 18 ] . additionally , nac is a source of cysteine , often the limiting precursor of de novo gsh synthesis [ 17 , 19 , 20 ] .
glutathione is an important antioxidant as it is the most abundant nonprotein thiol present in living cells , and its levels are commonly used as an indicator of intracellular antioxidant status .
furthermore , nac has been shown to influence redox - sensitive cell - signalling and transcription pathways , such as nf-b ( which regulates proinflammatory genes ) , the p38 , erk1/2 , sapk / jnk , c - jun , and c - fos pathways , among others , in a wide variety of different systems [ 17 , 21 , 22 ] .
n - acetylcysteine has been shown to promote cell growth and survival by activating the mapk pathway in response to ros - induced injuries ( which normally lead to growth arrest and apoptosis ) and is able to limit inflammatory processes , such as the release of proinflammatory cytokines .
accordingly , the cytoprotective effects of nac or l - nac against pq - induced cytotoxicity in a549 human lung adenocarcinoma cells were assessed by measuring cellular pq uptake , intracellular gsh content , ros levels , mitochondrial membrane potential , cellular gene expression , inflammatory cytokine release , and cell viability .
a549 cells possess many important biological properties of the alveolar epithelial type ii cell [ 23 , 24 ] and have been shown to be useful for studying the metabolic and macromolecule processing contributions of alveolar type ii cells to mechanisms of drug delivery at the pulmonary epithelium .
ccl-185 , american type culture collection , manassas , va , usa ) were maintained in costar 0.2 m vent cap cell culture flasks ( corning , corning , ny , usa ) with standard dulbecco 's modified eagle 's medium nutrient mixture f-12 ham ( sigma - aldrich , st .
louis , mo , usa ) supplemented with 10% iron - fortified bovine calf serum ( safc biosciences , lenexa , kan , usa ) , 2 mm l - glutamine ( gibco , carlsbad , calif , usa ) , and antibiotic / antimycotic ( 100 u / ml penicillin , 100 g / ml streptomycin , and 0.25 g / ml amphotericin b ; gibco ) .
cultures were incubated at 37c in a humidified atmosphere of 5% co2 in air and subcultured when 80% confluent . prior to plating
, cell counts and viabilities were assessed using a vi - cell xr cell viability analyzer ( beckman coulter , mississauga , on , canada ) .
paraquat ( paraquat dichloride x - hydrate , sigma - aldrich ) was dissolved in distilled water and diluted with culture media to prepare specific treatment concentrations .
experiments were performed using serum - free media . to determine the cytotoxicity of nac alone ,
cells were treated with control media or media containing different concentrations of nac ( 0 to 50 mm final nac concentrations ) . to determine the effect of nac or l - nac on the toxicity of pq
, cells were first pretreated with control , empty liposomes- ( el- ) nac- , or l - nac - containing media ( 5.0 mm for 4 h ) , followed by treatment with control or pq - containing media .
nac ( n - acetyl - l - cysteine , sigmaultra > 99% tlc ; sigma - aldrich ) was dissolved in pbs and adjusted to ph 7.4 to produce a 0.1 m stock solution .
following filter sterilization ( 0.2 m pore - size filters ) , specific volumes of n - acetylcysteine stock solution were added to culture media for the pretreatment / treatment of cells .
liposomal - n - acetylcysteine ( l - nac ) was prepared from a mixture of dppc ( dipalmitoylphosphatidylcholine ) and nac in a 7 : 3 molar ratio by using a dehydration - rehydration method as described in .
liposomal vesicle size was determined with a submicron particle sizer ( nicomp model 270 ) following rehydration and was found to have a mean diameter of 181.5 19.6 nm .
cell viability was measured with the mtt ( 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide ) assay as previously described in .
the intracellular levels of nac , pq , and gsh were determined by an ultraperformance liquid chromatographic ( uplc ) method using a waters acquity system equipped with a binary solvent manager , an automated sample manager , and a photodiode array detector ( waters , milford , mss , usa ) as described previously by mitsopoulos and suntres .
briefly , after each treatment , cells were harvested via trypsinization , washed twice with phosphate - buffered saline ( pbs ) , lysed via sonication ( 20 s , 100% amplitude ; sonic dismembrator model 500 , fisher scientific , pittsburgh , pa , usa ) , centrifuged , and then passed through a 0.2 m filter .
the ultrafiltrate was injected onto an acquity uplc hss t3 analytical column ( 2.1 mm i.d .
150 mm length , 1.8 m particles ) with a vanguard 2.1 mm i.d .
5 mm length guard column , at 30c . the mobile phase consisted of 23 mm ammonium formate ( ph 3 ) at a flow rate of 0.250 ml / min .
nac , pq , and gsh were measured at wavelengths of 200.3 , 257.7 , and 202.1 nm , respectively , and values were normalized to total protein using the micro lowry total protein kit - peterson 's modification ( sigma - aldrich ) , in accordance with the manufacturer 's instructions .
the intracellular levels of reactive oxygen species were determined by staining the cells with cm - h2dcfda ( 5-(and 6- ) chloromethyl-2,7-dichlorodihydrofluorescein diacetate , acetyl ester ) ( molecular probes , eugene , ore , usa ) in pbs as previously described in .
flow cytometric analysis was performed using a bd facscalibur flow cytometer ( bd biosciences , san jose , calif , usa ) with bd cellquest pro software .
mitochondrial membrane potential was assessed using the mitoprobe jc-1 assay kit for flow cytometry ( molecular probes ) .
following challenge , cells were washed with pbs and stained for 30 minutes with jc-1 ( 5,5,6,6-tetrachloro-1,1,3,3-tetraethylbenzimidazolylcarbocyanine iodide ) , a cationic dye that exhibits potential - dependent accumulation in mitochondria , under standard incubation conditions .
stained cells were detached from the plate surface and suspended in pbs for flow cytometric analysis using the fl1-h and fl2-h channels of a bd facscalibur flow cytometer ( bd biosciences ) with bd cellquest pro software .
mitochondrial depolarization was indicated by decreased red fluorescence intensity due to concentration - dependent formation of red fluorescent j - aggregates .
gene array analysis of cells challenged with 0.25 mm pq for 4 h following pretreatment with control , nac - containing or l - nac - containing media ( 5.0 mm for 4 h ) was performed as detailed previously in using the human stress and toxicity pathwayfinder rt profiler pcr array ( table 1 ; sa biosciences ) .
conventional rt - pcr analysis of cells challenged as indicated previously was performed using the rt qpcr primer assays ( table 2 ; sa biosciences ) .
the methodology was carried out similar to that outlined for the gene arrays with the exception that 1 l of the appropriate primer was manually added to each well of the icycler iq 96-well pcr plates ( bio - rad ) and was covered with microseal b film ( bio - rad ) .
cells seeded into sterile 25 cm culture flasks ( corning ) at 1.35 10 cells / flask were incubated to 80% confluence overnight , then washed with pbs and pretreated with control , nac - containing or l - nac - containing media ( 5.0 mm for 4 h ) followed by challenge with control or pq - containing media ( 0.25 or 1.0 mm for 4 h ) .
following incubation , media of treated cells were analyzed for cytokine levels using a human grp i cytokine 7-plex panel kit ( bio - rad ) specific for interleukin ( il)-1 , il-6 , il-8 , il-10 , il-15 , tnf- , and eotaxin , using a bio - plex 200 system ( bio - rad ) with bio - plex manager software in accordance with the manufacturer 's instructions .
data are presented as mean s.e.m ( n 3 ) and analyzed for statistical significance using the paired student 's t - test , with p < .05 considered significant . for normalized data , a paired one - sample t - test was performed comparing means to a hypothetical mean of 1 ( p < .05 ) .
challenge of a549 cells with nac at concentrations ranging from 0 to 10 mm did not have any effect on cell viability 24 h after nac exposure .
however , a 30% decrease in viability relative to control cells was observed following treatment with 50.0 mm nac ( figure 1(a ) ) .
the uptake of nac by a549 cells was assessed using uplc following treatment with 5.0 mm nac- or l - nac - containing media for 0 , 1 , 2 , 4 , 8 , and 24 h ( figure 1(b ) ) .
treatment of a549 cells with conventional nac resulted in increased nac uptake up to 2 h posttreatment ; thereafter , levels remained unchanged up to 24 h posttreatment .
cells treated with l - nac exhibited increased uptake over time , with maximal levels achieved following 4 h treatment . under all investigated conditions ,
the uptake of nac by a549 cells was significantly greater following treatment with the l - nac formulation compared to nac .
challenge of a549 cells with pq resulted in concentration - dependent decreases in cell viability ( figure 2 ) .
viability of cells challenged with pq ( 0.1 and 0.5 mm ) for 24 h was higher in those cells pretreated with l - nac .
in contrast , pretreatment with nac or empty liposomes ( el ) did not confer any observable effect on cell viability of pq - challenged cells under these conditions .
exposure of cells to increasing concentrations of pq for 24 h significantly decreased intracellular gsh content , which correlated with increases in cellular pq uptake , as measured by uplc ( figure 3 ) . in general , pretreatment with l - nac but
not nac resulted in lower pq - induced depletion in the levels of intracellular gsh content of cells .
pretreatment with nac or l - nac had no effect on the linear ( r = 0.969 ) uptake of pq in a549 cells challenged with increasing concentrations of pq ( figure 3(b ) ) .
ros levels increased following pq exposure ( figure 3(c ) ) , but pretreatment with nac or l - nac significantly reduced levels of ros in 0.25 and 1.0 mm pq - challenged cells ( 4 h ) to either basal or subbasal levels as assessed via flow cytometric analysis of cm - h2dcfda - stained cells ( figure 3(c ) ) .
the mitochondrial membrane potential of cells challenged with 0.25 mm pq for 4 h was significantly decreased relative to untreated control cells and was further decreased following 1.0 mm pq challenge .
pretreatment with l - nac was effective in preventing the decreases of mitochondrial membrane potential in both 0.25 and 1.0 mm pq - challenged cells , returning it to basal levels in the former , as well as increasing it nearly 2-fold when compared to untreated control cells ( figure 4 ) .
conversely , pretreatment with nac only significantly prevented the decrease in mitochondrial membrane potential of 0.25 mm pq - challenged cells , having no apparent effect on untreated control or 1.0 mm pq - challenged cells .
levels of il-8 secreted by cells exposed to 0.25 mm and 1.0 mm pq were significantly increased relative to untreated control cells ( figure 5 ) .
both nac and l - nac pretreatments decreased il-8 levels in untreated control cells and 0.25 mm pq - challenged cells , while l - nac , but not nac , was also able to significantly reduce levels of il-8 following 1.0 mm pq challenge .
levels of il-1 , il-6 , il-10 , il15 , tnf- , and eotaxin were not reliably detectable under these conditions .
changes in gene expression were assessed using a gene array designed to study genes involved with cellular stress and toxicity .
the magnitude of gene expression in cells pretreated with nac or l - nac prior to 0.25 mm pq challenge for 4 h was generally decreased relative to challenged cells with no pretreatment ( figure 6 ) .
fold changes ( relative to control cells ) of each gene of the array following pq challenge with no pretreatment , nac pretreatment , or l - nac pretreatment are listed in table 1 .
the expression of many oxidative or metabolic stress - related genes was not significantly altered under any of the studied conditions , with the exception of cyp1a1 and ptgs1 being significantly upregulated in pq - challenged cells pretreated with l - nac .
the expression of all studied heat shock genes remained more or less unchanged in pq - treated cells but hspa2 , hspa4 , and hspa1l were each significantly downregulated with nac or l - nac pretreatment .
the expression of egr1 was increased 2.0-fold in pq challenged cells in the absence of antioxidant pretreatment but its expression was maintained at control levels with l - nac pretreatment .
antioxidant pretreatment of cells subsequently challenged with pq had an effect on genes related to growth arrest and senescence as well .
briefly , gdf15 and ddit3 were both significantly upregulated 1.9-fold following pq challenge and were modulated with l - nac ( 1.4- and 1.5-fold , resp . ) , but not nac ( 2.0- and 2.2-fold , resp . ) , pretreatment .
cdkn1a was upregulated 1.5-fold following pq challenge and was progressively upregulated further with both nac ( 1.7-fold ) and l - nac ( 1.9-fold ) pretreatment .
il18 was upregulated 1.5-fold in pq - challenged cells , but its expression was modulated with nac or l - nac pretreatment . using individual primer assays with conventional rt - pcr
, we found il8 to be significantly upregulated ( 2.2-fold ) in pq - challenged cells with no pretreatment , but it was progressively modulated with nac ( 2.0-fold ) and l - nac ( 1.7-fold ) pretreatment .
it is worth noting that the il10 gene , which codes for the anti - inflammatory cytokine il-10 , was down - regulated in pq - challenged cells , an effect reversed by l - nac , but not nac , pretreatment . finally , the expression of many apoptosis signalling genes was not altered under the studied conditions with the exception of casp10 , which was upregulated 1.7-fold in pq - challenged cells with no pretreatment and was modulated by both nac and l - nac pretreatment .
the effect of l - nac was confirmed to not be a direct result of the lipids composing the liposomes as pretreatment with empty liposomes did not alter the expression compared to pq - challenged cells with no pretreatment ( table 2 ) .
conventional rt - pcr assays were performed to validate findings obtained from the gene arrays .
similar gene expression patterns were observed for the majority of the genes ( e.g. , cat , cyp1a1 , il1a , nfkbia , and sod1 ) analyzed by both methods .
figure 7 depicts a representative electropherogram of extracted rna , achieved using the experion automated electrophoresis station , indicating high rna integrity with little or no apparent degradation of 18 and 28 s rrna . additionally , a single peak ( or zero if no product was amplified )
was present in first - derivative dissociation curves for every pcr reaction on all gene arrays and conventional rt - pcr assays , indicating that only a single pcr product ( i.e. , the gene of interest ) was amplified in each case .
also , pretreatment of cells with empty liposomes did not confer any protection against pq - induced cytotoxicity ( figure 2 ) and gene array analysis ( table 2 ) .
the results of the present study showed that exposure of a549 cells to pq in vitro resulted in a concentration- and time - dependent accumulation of pq which was associated with concomitant increases in the intracellular levels of ros and decreases in gsh levels , confirming results from other studies that pq exerts its toxic effects , to a major extent , via oxidative stress mechanisms [ 13 , 26 ] .
accordingly , research efforts in the management of pq poisoning are also directed towards the use of antioxidants .
a potential antioxidant candidate is nac because not only it is available in the clinic but also its thiol group provides free radical - scavenging properties and it acts as a source of cysteine , often the limiting precursor of de novo gsh synthesis [ 3 , 17 , 18 ] . in order to assess the cytoprotective effects of both the conventional and liposomal nac formulations
nac has been reported to exhibit cytotoxicity at variable concentrations depending on cell type : 10 mm nac was nontoxic in human bronchial epithelial cells , 40 mm was nontoxic in 3t3 fibroblasts , and 50 mm was nontoxic in aortic endothelial cells ; however , 30 mm was cytotoxic in vascular smooth muscle cells , monocytes , and neutrophils , and as low as 5.0 mm nac was cytotoxic in porcine aortic endothelial cells
. studies involving nac in a549 cells have generally employed concentrations ranging from 1 to 10 mm [ 26 , 2831 ] .
our results indicate that concentrations of 10.0 mm or less had no negative impact on cell viability , while a greater concentration ( i.e. , 50.0 mm ) resulted in significantly decreased cell viability after 24 h ( figure 1 ) .
both nac formulations conferred protection against pq - induced cytotoxicity but generally l - nac was more effective than the conventional nac formulation in limiting the pq - induced decreases of cellular gsh content ( figure 3(a ) ) and production of ros ( figure 3(c ) ) .
the protective effect of nac or l - nac can not be attributed to the effect of the antioxidant formulations on pq uptake since nac or l - nac pretreatment had no effect on intracellular pq levels in a549 cells ( figure 3(b ) ) .
it is unclear whether this protective effect is a result of nac 's direct scavenging properties or the de novo synthesis of gsh using nac as a precursor .
the possible reason for the protective effects being more prominent in cells pretreated with l - nac was the greater and more sustainable intracellular nac levels that can be achieved via liposomal delivery ( figure 1(b ) ) .
cellular uptake experiments showed that the uptake of nac as a liposomal formulation was much greater ( i.e. , up to 4-fold ) under all conditions studied when delivered as l - nac compared to nac ( figure 1(b ) ) .
thus , the higher and more sustained intracellular nac levels are responsible for maintaining a normal cellular redox status as evidenced by the reduced production of ros and higher gsh levels . it should be noted that pretreatment of cells with empty liposomes consisting of dppc lipids did not alter the pq - induced changes in cytotoxicity and gene expression .
the mitochondria are thought to be essential targets of pq and important in its toxicity .
in fact , there is evidence that pq disrupts the mitochondrial electron transfer chain resulting in a reduction of metabolic function , and it is suggested that lesions due to pq first occur in the mitochondria [ 3234 ] .
pretreatment with nac or l - nac exhibited a beneficial effect on the mitochondrial membrane potential of pq - challenged cells ( figure 4 ) .
nac or l - nac pretreatment increased the membrane potential above control levels in 0.25 mm pq - challenged cells for 4 h , while l - nac , but not nac , pretreatment limited the decrease of membrane potential in cells exposed to 1.0 mm pq .
interestingly , control cells pretreated with l - nac exhibited nearly a 2-fold increase in fluorescence intensity relative to control cells with no pretreatment .
have shown that radioactively - labelled liposomal antioxidant vesicles were associated with mitochondria , and antioxidants that are selectively accumulated into mitochondria can inhibit mitochondrial oxidative damage that contributes to a range of degenerative diseases related to oxidative stress .
the maintenance of cellular redox status is crucial for cellular homeostasis , and its dysregulation towards a more oxidized intracellular environment is associated with aberrant transcriptional activation and gene expression affecting several processes such as cell growth , differentiation , and inflammation [ 22 , 3537 ] . in this study ,
the magnitude of pq - induced changes in gene expression in cells pretreated with nac or l - nac prior to 0.25 mm pq challenge for 4 h was generally lower with the l - nac being a more effective treatment than nac ( figure 6 ) .
although the exact mechanism(s ) by which nac affected the pathways involved in signal transduction and gene expression can not be delineated from the results of this study , it is possible that these pathways are regulated by oxidants and redox - sensitive steps since increasing levels of intracellular nac affect the steady state level of oxidants ( figure 3(c ) ) and can modify the redox status of the cell ( figure 3 ) , an effect known to exert a regulatory effect on transcriptional activation and gene expression [ 22 , 35 , 3840 ] .
for example , expression of gdf15 , il8 , egr1 , and casp10 genes is known to be upregulated in oxidative stress - induced conditions , a treatment effect counteracted by the presence of antioxidants [ 36 , 4147 ] .
the upregulation of gdf15 , a protein that plays a role in regulating inflammatory and apoptotic pathways in injured tissues and during disease processes [ 4850 ] , and egr1 , which encodes a transcriptional regulator that activates genes ( including p53 ) required for differentiation and mitogenesis , was maintained closer to normal levels in cells pretreated with l - nac , but not nac ( table 1 ) .
the expression of casp10 , which codes for the initiator caspase-10 involved in the death - inducing signaling complex during apoptosis ( bidere et al . ) , was upregulated 1.7-fold in pq - challenged cells but was closer to control levels in pq - challenged cells pretreated with nac or l - nac ( table 1 ) .
it is evident that the preservation of cellular homeostasis by l - nac , and to a lesser extent by nac , promoted cell survival .
paraquat administration has been shown to be associated with an infiltration of neutrophils in lung [ 5 , 53 ] .
interleukin-8 ( il-8 ) , a potent proinflammatory cytokine released in response to injury , has a key role in the recruitment and activation of neutrophils during inflammation [ 54 , 55 ] .
the expression of il8 gene was upregulated in pq - challenged cells , but its expression was substantially modulated with pretreatment of l - nac and to a lesser extent with nac ( table 2 ) .
the inhibitory effects of nac and l - nac on il-8 expression were correlated with comparable changes in il-8 protein secretion in the cell culture supernatant of pq - challenged cells ( figure 5 ) .
the ability of nac to modulate the upregulation of il-8 has been described in other studies as well : the increased il-8 gene and protein [ 57 , 58 ] expression of pq - challenged peripheral blood mononuclear cells was blocked by nac , and nac administration was found to inhibit the release of chemotactic factors for neutrophils and consequently reduce their infiltration into the lungs of pq - challenged rats .
oxidative stress , which occurs when the redox homeostasis within the cell is altered , is a key pleiotropic modulator which may be involved in the upregulation and/or downregulation of several genes [ 35 , 37 ] .
il10 , which codes for the anti - inflammatory cytokine interleukin-10 ( il-10 ) , is down - regulated 2.2-fold following pq - treatment ( table 2 ) , suggesting that the cell may be actively repressing anti - inflammatory mediators in favor of proinflammatory mediators ( e.g. , il-8 ) .
the ability of nac to prevent the downregulation of il-10 , being greater in cells pretreated with l - nac than nac , is an evidence to confirm that the higher intracellular levels of nac maintain the redox status of cells closer to normalcy . in conclusion
, the results of the present study suggest that pretreatment of a549 cells with nac , both in its conventional and liposomal form , conferred cytoprotection against pq - induced toxicity .
this was mainly attributed to its ability to ameliorate cellular redox status ( i.e. , intracellular gsh content and ros levels ) and was independent of pq uptake .
these protective effects were more evident in cells pretreated with l - nac , which is attributed , at least in part , to the increased nac levels achieved via liposomal delivery .
Output:
| paraquat ( pq ) is a herbicide that preferentially accumulates in the lung and exerts its cytotoxicity via the generation of reactive oxygen species ( ros ) .
there is no specific treatment for paraquat poisoning .
attempts have been made to increase the antioxidant status in the lung using antioxidants ( e.g. , superoxide dismutase , vitamin e , n - acetylcysteine ) but the outcome from such treatments is limited .
encapsulation of antioxidants in liposomes improves their therapeutic potential against oxidant - induced lung damage because liposomes facilitate intracellular delivery and prolong the retention of entrapped agents inside the cell . in the present study , we compared the effectiveness of conventional n - acetylcysteine ( nac ) and liposomal - nac ( l - nac ) against pq - induced cytotoxicity and examined the mechanism(s ) by which these antioxidant formulations conferred cytoprotection .
the effects of nac or l - nac against pq - induced cytotoxicity in a549 cells were assessed by measuring cellular pq uptake , intracellular glutathione content , ros levels , mitochondrial membrane potential , cellular gene expression , inflammatory cytokine release and cell viability .
pretreatment of cells with l - nac was significantly more effective than pretreatment with the conventional drug in reducing pq - induced cytotoxicity , as indicated by the biomarkers used in this study .
our results suggested that the delivery of nac as a liposomal formulation improves its effectiveness in counteracting pq - induced cytotoxicity . |
PubmedSumm118645 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: prolyl oligopeptidase is known to play an important role in many
cognitive disorders such as parkinson s disease , as well as depression and schizophrenia .
nevertheless
clinical applications of peptides have been limited so far , for instance
by their low systemic stability or lack of oral bioavailability .
to bridge the gap of suitable peptide leads
and optimized peptide candidates for preclinical studies , the potential of cyclotides as pop inhibitors has been investigated
in the present study .
plants of three rubiaceae species , i.e. , psychotria solitudinum , p. poeppigiana ,
and p. capitata , were collected in the field in costa
rica .
briefly , the dried and pulverized plant material was extracted
with dcm / methanol , and the resulting filtrate was further treated
with reversed - phase ( rp ) solid - phase extraction .
this yielded an enriched
portion of hydrophobic compounds such as cyclotides present in those
extracts .
these extracts were characterized by mass spectrometry ( ms )
and high - performance liquid chromatography ( hplc ) ( figure 1 ) .
this peptidomics - based analytical workflow has
been previously established and appeared to be
a rapid tool for the identification of cyclotides in the psychotria extracts .
molecular weight signals in the range 25003500
da that typically correspond to the presence of cyclotides were recorded
by maldi - tof ms in all three psychotria extracts
( figure 1a c ) , and previously reported
cyclotides psysol 1 , psypoe 1 , and psycap 1 could be identified .
furthermore , in agreement with an earlier study
analytical hplc analysis of these extracts revealed late - eluting peak
patterns in rp gradientstypical for cyclotide - containing samplesindicating
the presence of cyclotides in these psychotria extracts . the prototypic cyclotide plant v. tricolor has been known as a rich source of cyclotides , and accordingly numerous
cyclotides have been identified in the viola extract , for example , kalata s , varv c , varv d , varv e , varv f , vaby b , kalata
b1 , vigno 3 , cycloviolacin o12 , and cycloviolacin o20 ( figure 1d ) .
cyclotide
extracts of plant species , i.e. , psychotria solitudinum ( a ) , psychotria poeppigiana ( b ) , psychotria
capitata ( c ) , and viola tricolor ( d ) , were
analyzed using maldi - tof ms ( left panels ) and rp - hplc ( right panels ) .
maldi - tof spectra are presented in the range 25003500 da of
each plant extract , indicating signals in a m / z range typical for cyclotides .
the molecular weights of
major monoisotopic [ m + h ] signals were compared to those
of known cyclotides ( www.cybase.org.au or koehbach et al . ) , identified , and labeled with names and their
corresponding molecular weight .
hplc analysis was performed using
linear gradients as described in the experimental
section , and a280 traces are presented ;
the gray boxes indicate hplc fractions that have been used for pop
inhibition screening ( see supplementary table
s1 ) .
plants of the psychotria alliance within the rubiaceae
family offer a rich source of cyclotides .
indeed , psychotria cyclotides comprise prototypic
features of the cyclotide family , which are in particular ( i ) the
presence of the cck motif , which confers them with the frequently
reported stability , and ( ii ) the sequence
diversity of cyclotide loop residues , which makes them an attractive
peptide library for bioactivity screening .
apart from cyclic momordica tis , cyclotides have
to the best of our knowledge never been characterized for their potential
as inhibitors of proteolytic enzymes .
specifically it was of interest
to study their inhibitory effects toward human pop , an enzyme that
has been identified as a promising pharmaceutical target .
cyclotide extracts
of p. solitudinum , p. poeppigiana , p. capitata , and v. tricolor were
characterized for their effect toward the inhibitory activity of purified
human pop in a classical enzyme inhibition assay setup similar to
that described earlier by toide and colleagues . using a high - throughput 96-well plate assay the activity
of the enzyme was determined in the presence of different concentrations
of the plant extracts .
pop activity was measured by fluorimetry using
z - gly - pro - amc as substrate following the fluorescent signal upon the
enzymatic release of amc .
the amount of fluorescence of the control
samples containing only pop enzyme and buffer was defined as 100%
activity .
the activity of the corresponding cyclotide extracts was
measured and normalized to the activity of the control ( eq 1 , experimental section ) .
extracts from psychotria species exhibited strong
inhibitory effects : at 100 g / ml of cyclotide extract ( the lowest
concentration tested ) , pop had a remaining activity of 32% , 23% , and
20% , respectively , in the presence of p. poeppigiana , p. capitata , and p. solitudinum extract , respectively ( figure 2 ) .
almost
full inhibition was observed when applying 400 g / ml of cyclotide
extract ; that is , the remaining pop activities were 15% for p. poeppigiana , 9% for p. capitata , and
10% for p. solitudinum .
the viola plant extract also exhibited pop inhibitory effects ranging from
2% to 17% remaining pop activity ( figure 2 ) .
for all extracts tested , the pop inhibition was concentration - dependent ,
and therefore it was reasonable to assume that the observed effects
were due to a molecular interaction of pop with cyclotides of the
plant extracts .
cyclotide extracts ( as shown in figure 1 ) of psychotria solitudinum , psychotria
poeppigiana , psychotria capitata , and viola tricolor were dissolved in ddh2o for the
pop activity assay at concentrations of 100400 g / ml
and tested for their potential to inhibit pop .
the measurements were
performed in triplicate , and the data are presented as mean
stdev . this hypothesis is in agreement
with previous observations that
squash tis isolated from the seeds of momordica species
inhibit the activity of other serine proteinases . due to the importance of pop in human disease and knowing that pop substrates and cyclotides
are similar in molecular size , we attempted to isolate and identify
cyclotides that were able to inhibit the activity of human pop using
a bioassay - guided fractionation approach .
the four cyclotide extracts that exhibited
potent inhibition of pop
activity were fractionated by rp - hplc as previously described .
the crude extracts , containing numerous cyclotides ,
were separated by preparative rp - hplc in three to four fractions ,
as indicated by the gray shading in the chromatograms of figure 1 .
those fractions were forwarded to the pop inhibition
assay and tested again in three concentrations of 100 , 200 , and 400
g/l for each fraction ( supplementary
table s1 ) .
all fractions of each plant extract were capable
of inhibiting the activity of pop to a certain percentage ; for example ,
fraction 3 of p. solitudinum ( psysol - f3 ) inhibited
pop activity by 4878% , fraction 4 of p. poeppigiana ( psypoe - f4 ) by 4783% , and fraction 2 of v. tricolor ( vitri - f2 ) by 5186% , respectively . according to maldi - tof
ms analysis , fraction vitri - f2
does not appear to contain many cyclotides ,
but mainly other small organic plant compounds that may be responsible
for its pop inhibitory activity ( data not shown ) .
three fractions
of p. solitudinum were further characterized to determine
quantitative pop inhibition data ( ic50 ) and to purify an
active cyclotide .
consequently , for all three fractions psysol - f1f3
a concentration - dependent inhibition assay of pop was performed to
confirm the initial results .
psysol - f3 yielded the highest potency
( ic50 = 100.4 g / ml ) , whereas fraction psysol - f1
( ic50 = 237.2 g / ml ) and fraction psysol - f2 exhibited
about 3-fold less potency ( ic50 = 285.2 g / ml ) to
inhibit the enzymatic activity of human pop ( table 1 , figure 3a ) .
in addition we tested
pop inhibition of a subfraction of vitri - f3 , i.e. , the most potent
cyclotide - containing v. tricolor fraction .
this fraction
comprised a coeluting cyclotide mixture of kalata s and kalata b1
( supplementary figure s1 ) , which exhibited
a concentration - dependent inhibition of pop activity with an ic50 of 28.5 g / ml ( table 1 , figure 3b ) .
( a ) concentration - response inhibition curves of three psychotria solitudinum fractions ( psysol - f1f3 ) after
rp - hplc fractionation of the cyclotide extract .
each data point is
presented as the mean stdev of two independent experiments
or as the mean of three replicates , respectively ( see table 1 ) .
the inhibitory potency was quantified using nonlinear
regression analysis , yielding ic50 values of 237.2 g / ml
( psysol - f1 ) , 285.2 g / ml ( psysol - f2 ) , and 100.4 g / ml
( psysol - f3 ) .
similarly , viola tricolor fraction ( vitri - f3 )
was purified by rp - hplc to yield sample sub - vitri - f3 .
this subfraction
comprises mainly the two coeluting cyclotides kalata s and kalata
b1 ( supplementary figure s1 ) .
( b ) the fraction
exhibited a pop inhibitory potency ( ic50 ) of 28.5 g / ml .
the most potent fraction of psychotria solitudinum ( psysol - f3 ) was further purified to obtain the isolated cyclotide
psysol 2 ( 1 ) , which inhibited human pop activity in a
concentration - dependent manner with an ic50 of 25 m
( c , solid line ) . to confirm the inhibition of human pop by plant - extracted
cyclotides ,
psysol 2 ( 1 ) and kalata b1 were synthesized
and analyzed ; synthetic psysol 2 ( 1 ) ( c , dashed line )
inhibits human pop activity in a concentration - dependent manner with
an ic50 of 27.8 m , and synthetic kalata b1 yielded
an ic50 of 5.6 m ( d ) .
ic50 values are calculated
using nonlinear regression analysis and are presented as mean
stdev of at least two independent experiments ( as described in the experimental section ) .
the most potent p. solitudinum fraction ,
psysol - f3 , contained one major
compound ( 1 ) , as determined by rp - hplc ( figure 4a ) , with a molecular weight of 2904.12 da ( figure 4b ) .
this peptide was purified using semipreparative
rp - hplc , and its purity of 95% and its molecular weight were
confirmed by analytical rp - hplc ( figure 4c )
and maldi - tof ms ( figure 4d ) , respectively .
to determine the peptide sequence of compound 1 , which
was named psysol 2 ( psychotria solitudinum cyclotide
2 )
initially the cysteine content
of the peptide was determined by a combination of reduction and alkylation .
purified psysol 2 ( 1 ) was treated with dithiothreitol
( dtt ) , and the reduced sulfhydryl groups were modified with iodoacetamide .
this chemical derivatization resulted in an addition of 348.1 da ,
which corresponds to the presence of six cysteine residues ( figure 5a , b ) .
subsequently the reduced and s - alkylated aliquots
of psysol 2 ( 1 ) were digested with trypsin or endoproteinase
gluc to confirm the presence of a circular backbone and to elucidate
the peptide s primary sequence by de novo peptide
sequencing . upon trypsin and endoproteinase gluc digest of the sulfhydryl - reduced
and s - alkylated peptide ,
its molecular weight increased by 18 da as
a result of the addition of h2o during ring - opening
of the backbone - cyclized peptide ( figure 5c , d ) ;
this confirmed the cyclic nature of psysol 2 ( 1 ) , and
it indicated the presence of one lys or arg residue and one glu residue
in the peptides sequence , respectively .
manual interpretation
of the ms / ms peptide fragmentation pattern of each digest revealed
the sequence of psysol 2 ( 1 ) ( figure 5c , d ) . since the two isobaric residues leu and ile can not be
resolved by ms / ms fragmentation , homology alignment analysis ( www.cybase.org.au ) of psysol 2 ( 1 ) to other known cyclotides , in particular to closely related psychotria cyclotides , has been performed ; hence this combined
approach led to the identification of the psysol 2 ( 1 ) sequence as cyclo - glpicgescvggtcntpgctctwpvctrn ( figure 6a ) .
the analytical a280 hplc trace of psychotria solitudinum fraction 3 ( psysol - f3 ) ( a ) and its
corresponding maldi - tof spectrum
( b ) are shown , indicating the presence of one main compound in this
fraction .
using rp - hplc separation a single compound , 1 , could be isolated from this fraction .
this purified compound 1 was characterized by rp - hplc ( c ) and maldi - tof ms ( d ) .
inset
in ( d ) shows the isotope pattern of psysol 2 ( 1 ) .
the isolated active compound 1 of psychotria
solitudinum was characterized by chemical derivatization
and ms .
using sulfhydryl reduction by dtt a mass shift of 6 da ( 2911.12 m / z ) compared to the native mass signal
of 2905.12 m / z was observed , indicating
the presence of six cysteine residues ( a ) .
subsequently , iodoacetamide
derivatization yielded the mass of 3253.22 m / z , corresponding to s - carbamidomethylation of the six cysteines
( b ) .
de novo amino acid sequencing was performed by interpretation
of ms / ms fragmentation spectra using trypsin ( c ) and endoproteinase
glu c ( d ) digests .
the sequence was determined by manual assignment
of the n - terminal b - ion and c - terminal y - ion series and the ion fragmentation
calculator tool ( data explorer ab sciex ) . the disulfide connectivity
of cys i iv , cys ii v , and cys iii
vi and the
isobaric amino acids leu and ile were assigned based on homology with
known sequences . sequence alignments and homology model of psysol 2 ( 1 ) . (
a ) the amino acid sequence of psysol 2 ( 1 ) was used
for alignment based on the conserved cck motif with the prototypic
cyclotides kalata b1 ( mbius type ) , cycloviolacin o2 ( bracelet ) ,
and mcoti-1 ( cyclic ti ) . the structural model of the novel cyclotide
psysol 2 ( 1 ) was obtained with the cyclomod tool ( www.cybase.org ) , and the structural features were compared
to kalata b1 ( pdb code : 1nb1 ) , cycloviolacin o2 ( 2knm ) , and mcoti-1 ( 1ib9 ) .
all structures
are presented as ribbon cartoons , which were prepared using pymol .
-sheet motifs are indicated by flat arrows , and the disulfide
bonds are highlighted in yellow . since psysol 2 ( 1 ) contains six cysteine residues
and a circular peptide backbone , it is likely to form the typical
cck motif .
the presence of a pro residue
in loop 5 allowed classification of psysol 2 ( 1 ) as a
mbius - type cyclotide due to sequence homology to other cyclotides
of this subfamily ( figure 6 a ) .
in addition to the similar molecular sequence
of psysol 2 ( 1 ) and known cyclotides , the structural
similarity has been confirmed by modeling of psysol 2 ( 1 ) using the cyclomod tool of cybase ( figure 6b ) .
the sequence alignment of prototypic cyclotides
with psysol 2 ( 1 ) , namely , kalata b1 ( mbius ) ,
cycloviolacin o2 ( bracelet ) , and mcoti-1 ( cyclic ti ) clearly demonstrated
that psysol 2 ( 1 ) has the highest homology with kalata
b1 , with only three residues differing , in positions 4 , 7 , and 22 .
compared to cycloviolacin o2 , psysol 2 ( 1 ) lacks the
cationic residues in loop 5 and the hydrophobic residue in loop 3 .
as mentioned above , the momordica tis and cyclotides
share only the cck motif , and hence psysol
2 ( 1 ) and mcoti-1 have little sequence homology .
the
psysol 2 ( 1 ) model further predicted a triple - stranded
-sheet as a secondary structure element , which is typical for
mbius - type cyclotides .
plant purified
psysol 2 ( 1 ) was tested for pop inhibitory
activity , and as expected from bioassay - guided fractionation , it inhibited
human pop activity with an ic50 of 25 0.3 m .
the activity was confirmed with a synthetic psysol 2 cyclotide ( supplementary figure s2 ) , which exhibited an
ic50 of 27.8 m ( table 1 ,
figure 3c ) . since psysol 2 ( 1 )
and kalata b1 share high sequence homology and knowing that the active v. tricolor fraction vitri - f3 contains kalata b1 , we synthesized
this cyclotide ( supplementary figure s2 ) and analyzed its pop inhibitory activity .
kalata b1 was slightly
more potent and inhibited human pop activity with an ic50 of 5.6 m ( table 1 , figure 3d ) .
these observed differences in activity may be
due to the amino acid differences and/or minor structural variation
between the two cyclotides .
similar plant peptides , namely ,
the family of cyclic and acyclic squash ti peptides , are well - known
inhibitors of trypsin and chymotrypsin . to determine inhibitor specificity
of cyclotides , we therefore tested the ability of kalata b1 and psysol
2 ( 1 ) to inhibit the activity of those two pancreatic
enzymes ( supplementary figure s3 ) .
interestingly ,
cyclotides were not capable of inhibiting the activity of trypsin
or chymotrypsin at concentrations of 25 and 75 m , respectively .
this suggests that cyclotides , and in particular kalata b1 , are at
least an order of magnitude more selective toward inhibition of pop
over trypsin and chymotrypsin .
it is noteworthy that psysol
2 ( 1 ) and kalata b1 contain
three proline residues each ( figure 6 ) , and
prolyl groups are thought to be a key feature of many pop substrates .
this is also the case for other active cyclotides
that have been identified in the pop inhibitory fractions of the other
plant extracts ( figure 1 ) ; most of them contain
three proline residues , in loops 3 , 5 , and 6 , respectively ( supplementary figure s4 )
. it will be interesting
in future studies to determine the importance of those pro residues
for the inhibitory activity of cyclotides .
in summary the observed
bioactive properties and structural features of cyclotides warrant
further investigations for applications of these interesting circular
peptides as human pop inhibitors .
the vast majority of previously
known pop inhibitors are small - molecule
peptidomimetics based on systemic modifications of the canonical compound
benzyloxycarbonyl - prolyl - prolinal ( z - pro - prolinal ) .
this compound
acts as a transition - state analogue due to the presence of a covalent
group acting as a warhead .
although many peptidomimetics , for example , s-17092 , z-321 , jtp-4819 ,
and ono-1603 , have been described as pop inhibitors with micromolar
to nanomolar potencies , the presence of a warhead moiety is an important
parameter to obtain inhibitory potencies in the low nanomolar range . despite some initial success as potential therapeutics of cognitive
deficits associated with aging and alzheimer s disease ,
the
development of these peptidomimetics was discontinued during clinical
phase i and ii , respectively . due to
a lack of public information , it is not clear why these compounds
failed , but most known pop inhibitors comprise the narrow family of
pyrrolidinyl analogues . to our knowledge
it has been repeatedly highlighted that cyclotides are
an emerging peptide class with enormous potential in medicinal chemistry
and for pharmaceutical applications .
therefore , cyclotides may be
promising tools for the development of novel peptide - based pop inhibitor
drugs
. the most interesting features of cyclotides are their
circular peptide backbone and the cystine - knot fold constituting the
cck motif .
together this improves the stability of these peptides ,
and hence cyclotides are known to be heat - stable , resistant to proteolytic
degradation , and unaffected by the acidic ph conditions in the gastrointestinal
tract , all of which are prerequisites
for conferring peptides with oral bioavailability .
it has been well documented that the majority
of the amino acids within the intercysteine loops are amenable to
variation without affecting cck topology , and indeed hundreds of cyclotides displaying unique amino acid sequences
have been isolated from plants .
this natural variation together with the structural plasticity
of cyclotides has been recognized by peptide chemists to engineer
novel cyclotide - based peptide therapeutics , by grafting of linear and otherwise
unstable bioactive amino acid sequences onto the intercysteine loops
of cyclotides to protect them from degradation within
the stabilized cck framework .
although
peptide grafting is a promising tool in drug development , there are examples of naturally occurring cyclic
or disulfide - knotted peptides , which appeared to be potent protease
inhibitors . for example a cyclic peptide stabilized by one disulfide
bond is the sunflower - trypsin inhibitor sfti-1 , which inhibits serine
proteases .
sfti-1 is considered to be the smallest known peptide trypsin
inhibitor ( 14-mer ) and belongs to the bowman - birk inhibitor family .
as mentioned above , squash tis are also potent inhibitors of trypsin
and chymotrypsin , and this includes in
particular the cyclotide - like cyclic squash tis isolated from momordica plants .
the present
study has confirmed these previous examples that cyclic or disulfide - knotted
peptides , and in particular cyclotides , are naturally occurring inhibitors
of serine proteases .
in addition , we were able to demonstrate that
mbius - type cyclotides do not inhibit the enzymatic activity
of trypsin and chymotrypsin , but appear to be specific for inhibition
of prolyl - oligopeptidase .
the combination of having a natural peptide
template with intrinsic inhibitory potency against proteases and knowing
that the cck - fold is amenable to peptide engineering for optimization
of this given activity makes the family of cyclotides interesting
natural molecules for future investigations regarding design and development
of human pop inhibitors . to conclude , the present study described
the identification of
the cyclotides kalata b1 and psysol 2 ( 1 ) to inhibit
human pop activity in vitro .
this may have provided
lead compounds for further investigation in the field of pop therapeutics .
there are currently no pop inhibitors available as approved drugs ,
and consequently there is a need for discovery and development of
suitable and improved pop inhibitors .
cyclotides can be regarded as
the first of a novel class of circular peptide pop inhibitors . due
to their known potential in peptide drug development
, cyclotides
appear to be an interesting class of natural products for future studies
to design and develop human pop inhibitors .
rp - hplc
was performed
using a dionex ultimate 3000 station ( dionex , amsterdam , the netherlands ) .
the device was equipped with a binary pump , autosampler , column
oven , multiwavelength detector , and fraction collector .
absorbance
wavelengths of 214 , 254 , and 280 nm were recorded of all analytical
and preparative separations .
psychotria plant
material ( psychotria
solitudinum , p. capitata , and p.
poeppigiana ) was collected in costa rica at the tropical
research station la gamba , and species were identified by h. greger
and a. berger ( university of vienna , austria ) .
herbarium accession numbers are hg-2607083 , hg-24070811 ,
and hg-3007081 , respectively . collection and export of plant material
were kindly permitted by the costa rican ministry of ambient and energy
under permit numbers 050 - 2013-swac , 217 - 2012-swac , and dgvs-109 - 2013 ,
respectively .
samples were dried , stored at 23 c , and protected
from moisture and uv irradiation until extraction . pulverized viola tricolor l. ( violaceae ) plant material ( herba violae
tricoloris plv . )
cyclotide extracts were prepared
as previously described . briefly , dry
plant material was ground using a coffee grinder and extracted for
24 h in 100200 ml of dichloromethane / methanol , 1:1 ( v / v ) ,
by continuous agitation at 23 c .
after filtration , 0.5 vol of
ddh2o was added , and the methanol / water phase , which contained
the enriched cyclotide mixture , was obtained by liquid / liquid phase
separation .
first , the methanol content was reduced
to less than 10% vol by dilution with ddh2o .
c18 irregular
4063 m material ( zeochem , uetikon , switzerland ) that
has been activated with methanol and equilibrated using 0.1% trifluoroacetic
acid ( tfa ) .
the aqueous extract was applied to the c18 material ,
washed with ddh2o / ch3cn / tfa , 90/10/0.1% ( v / v / v ) ,
and eluted with ddh2o / ch3cn / tfa , 20/80/0.1%
( v / v / v ) .
these eluates were lyophilized and reconstituted in ddh2o buffer prior to the pop inhibition tests or in 0.1% tfa
for mass spectrometry based analysis or hplc separation .
further
cyclotide purification was achieved by preparative chromatography
with a phenomenex jupiter c18 column ( 250 20.2 mm ,
10 m ) , and semipreparative separation was carried out with
a dichrom kromasil c18 column ( 250 10 mm , 5 m ) .
flow rates were set to 8 and 3 ml / min , respectively , and the solvents
consisted of 0.1% tfa ( solvent a ) or ddh2o
/ ch3cn / tfa , 10/90/0.1% ( v / v / v ) ( solvent b ) .
linear gradients from 5%
to 65% solvent b ( 1% per min ) were applied to achieve separation of
extracts .
resulting fractions were freeze - dried and analyzed by analytical
hplc using a phenomenex kinetex ( 150 3 mm , 2.1 m ) column .
purified cyclotide psysol 2 ( 1 ) was further structurally
characterized by de novo peptide sequencing using
maldi - tof / tof and homology modeling using cybase tools .
cyclotide structural elucidation
of the cyclotide psysol 2 ( 1 ) was performed by ms using
a maldi - tof / tof 4800 analyzer from ab sciex ( framingham , ma , usa )
as previously described .
peptide mapping
of plant extracts or hplc fractions was performed by dissolving dried
sample material in 0.1% tfa .
the samples were mixed at a ratio of
1:6 ( v / v ) with a matrix solution consisting of saturated -cyano-4-hydroxycinnamic
acid ( sigma - aldrich , st .
louis , mo , usa ) in ddh2o / ch3cn / tfa , 50/50/0.1% ( v / v / v ) .
a 0.5 l aliquot of the
mixture was directly spotted onto the maldi target plate , and the
droplet was allowed to air - dry .
mass spectra were obtained by combining
2500 shots in the spectral range 2500 to 4500 m / z using the ms reflector positive ionization mode . for de novo
sequencing peptides were dissolved at a concentration
of 5 mg / ml in 0.1 m nh4hco3 ( ph 8.0 ) , and disulfide
bonds were reduced using dtt in a final concentration of 10 mm for
60 min at 37 c .
the sample was s - alkylated using iodoacetamide
( 100 mm ) for 10 min in the dark ; remaining alkylation reagent was
quenched by addition of dtt ( 5 mm ) .
prior to ms / ms fragmentation the
peptide was digested with 0.2 g of trypsin
( sigma - aldrich ) or 0.4 g of endoproteinase gluc
proteomics grade
the digest was performed at 37 c for 1618 h , and
the peptide mixture was quenched using 0.5% tfa followed by ziptip
desalting ( millipore , billerica , ma , usa ) .
precursor fragmentation
was obtained in the ms / ms positive 1 kv reflector mode by acquiring
approximately 5000 spectra using optimized laser intensity and digitizer
enhancement settings .
the cyclotide amino acid sequence was obtained
by manual assignment of n - terminal b - ion and c - terminal y - ion series
and automated sequence analysis using the dataexplorer software ( ab
sciex ) .
the disulfide connectivity of cysi - iv , cysii - v , and cysiii - vi
and the isobaric amino acids leu and ile were assigned based on homology
with known sequences .
the three - dimensional structure
of the cyclotide psysol 2 ( 1 ) was performed by homology
modeling using the cyclomod tool on cybase ( www.cybase.org.au ) .
structural images were prepared using pymol from the pdb files
for kalata b1 ( 1nb1 ) , cycloviolacin o2 ( 2knm ) , and mcoti-1 ( 1ib9 ) .
the cyclotides psysol 2 ( 1 ) and kalata
b1 have been synthesized by fmoc - based solid - phase
peptide synthesis , folded , and analyzed using previously established
protocols .
several concentrations of cyclotide extracts or fractions between
100 and 400 g/l were used for the measurement .
the purity
of isolated or synthesized psysol 2 ( 1 ) and kalata b1
was evaluated with rp - hplc at a280 , and
their concentrations were determined using the beer
lambert
law with the molar absorption coefficients of 5875 cm m ( psysol 2 ) and 6410 cm m
human pop ( 2 l of a 6 m solution ; prepared by
recombinant expression according to tarrago et al . ) was preincubated for 15 min at 30 c with buffer
( 137 l of a 0.1 m na2hpo4 and kh2po4 ( 1:1 , w / w ) solution , ph 7.4 ) and the corresponding
cyclotide extract solution ( 3 l ) or ddh2o ( 3 l ,
controls ) .
after preincubation , pop substrate ( z - gly - pro - amc , 10 l
of a 3 mm solution prepared in 40% 1,4-dioxane ; bachem , bubendorf ,
switzeland ) was added , and the reaction mixture was incubated while
shaking ( 90 rpm ) for 1 h at 37 c .
the excitation and emission wavelengths were 360
40 and 485 20 nm , respectively .
the percentage of inhibition
was calculated as1where x is the activity of
pop in the absence of the inhibitor and y is the
activity in the presence of the cyclotide solution . the ic50 value was defined as the concentration of compound required to inhibit
50% of pop activity under these assay conditions .
inhibition curves were
generated by plotting the logarithmic concentrations vs enzyme activity ,
and ic50 values were calculated by fitting the data to
a three - parameter hill equation using nonlinear regression analysis .
each inhibitory experiment was repeated independently twice , unless
otherwise stated , and ic50 values were calculated from
each biological repeat and are presented as mean stdev .
bovine trypsin ( 10 l of a 10 ng/l solution ; roche , basel ,
switzerland ) or bovine -chymotrypsin ( 10 l of a 2.5
ng/l solution ; sigma - aldrich ) was preincubated for 15 min at
37 c with buffer ( 125 l of a 20 mm tris - hcl solution ,
ph 8.0 ) and with 3 l of the cyclotide solution or ddh2o as negative control .
after preincubation , trypsin substrate ( bz - arg - amc - hcl ,
10 l of a 3 mm solution prepared in 40% 1,4-dioxane ; bachem ,
bubendorf , switzerland ) or chymotrypsin substrate ( ala - ala - phe - amc ,
10 l of a 3 mm solution prepared in 40% 1,4-dioxane ; sigma - aldrich ) ,
respectively , was added , and the reaction was incubated while shaking
( 90 rpm ) for 1 h at 37 c .
the reaction was stopped with sodium
acetate ( 150 l , 1 m , ph 4 ) , and the formation of amc was measured
by fluorimetry .
the excitation and emission wavelengths were 360
40 and 485 20 nm , respectively .
phenylmethane - sulfonylfluoride
( pmsf ; 3 l of a 5 mm solution in dmso ) was used as a positive
control of inhibition ; additional controls with dmso solution only
were also performed .
data were calculated as percentage of inhibition
and are presented as mean stdev ( of three replicates ) .
Output:
| cyclotides are head - to - tail cyclized
peptides comprising a stabilizing
cystine - knot motif . to date
, they are well known for their diverse
bioactivities such as anti - hiv and immunosuppressive properties . yet
little is known about specific molecular mechanisms , in particular
the interaction of cyclotides with cellular protein targets .
native
and synthetic cyclotide - like peptides from momordica plants are potent and selective inhibitors of different serine - type
proteinases such as trypsin , chymotrypsin , matriptase , and tryptase - beta .
this study describes the bioactivity - guided isolation of a cyclotide
from psychotria solitudinum as an inhibitor of another
serine - type protease , namely , the human prolyl oligopeptidase ( pop ) .
analysis of the inhibitory potency of psychotria extracts
and subsequent fractionation by liquid chromatography yielded the
isolated peptide psysol 2 ( 1 ) , which exhibited an ic50 of 25 m .
in addition the prototypical cyclotide kalata
b1 inhibited pop activity with an ic50 of 5.6 m .
the inhibitory activity appeared to be selective for pop , since neither
psysol 2 nor kalata b1 were able to inhibit the proteolytic activity
of trypsin or chymotrypsin .
the enzyme pop is well known for its role
in memory and learning processes , and it is currently being considered
as a promising therapeutic target for the cognitive deficits associated
with several psychiatric and neurodegenerative diseases , such as schizophrenia
and parkinson s disease . in the context of discovery and development
of pop inhibitors with beneficial adme properties , cyclotides may
be suitable starting points considering their stability in biological
fluids and possible oral bioavailability . |
PubmedSumm118646 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: it is generally accepted that the cellular antioxidant enzymes belong to a group of the oxidoreductase enzymes maintaining the cellular redox homeostasis .
however , the importance of antioxidant enzymes is given a spotlight after a paradigm shift of the cellular function of reactive oxygen species ( ros ) from toxic respiratory by - products to a signaling second messenger .
peroxiredoxin ( prx ) is a family of antioxidant enzymes exhibiting peroxidase activity which reduces the hydroperoxides to water in the presence of proper electron donors .
prxs are classified by the number of cysteine residues involved in the peroxidase activity : 2-cys prxs and 1-cys prx .
the 2-cys prxs form a disulfide bond by reacting with the peroxides and the disulfide is reduced by thioredoxin which is coupled with thioredoxin reductase and nadph . therefore ,
2-cys prxs are the first thioredoxin - dependent peroxidase enzymes [ 1 , 2 ] .
the 2-cys prxs are purely cysteine - based peroxidase enzymes with no cofactor or selenocysteine requirement .
typical 2-cys prxs ( prx1prx4 ) are active as dimers organized in antiparallel fashion : that is , the peroxidatic cysteine residue ( cp ) in the amino terminus of one subunit reacts with the hydroperoxides and the resulting cp sulfenic acid forms a disulfide linkage with the sulfhydryl group of resolving cysteine residue ( cr ) in carboxyl terminus of another subunit .
in contrast , an atypical 2-cys prx ( i.e. , prx5 ) catalyzes the h2o2 reduction reaction through the formation of intramolecular disulfide linkage .
the 2-cys prx enzymes have distinct roles in diverse cellular processes , such as proliferation , migration , apoptosis , and metabolism , and are fundamentally supported by a broad distribution of the isoforms throughout the subcellular compartments .
prx3 is a major mitochondrial peroxidase responsible for efficient elimination of h2o2 , which is continuously produced by the dismutation of superoxide anions formed as a result of a partial reduction of the dissolved oxygen molecules during mitochondrial respiration .
recent studies indicate that prx4 is involved in the oxidative protein - folding pathway by the reoxidation of protein disulfide isomerase [ 5 , 6 ] .
the distribution of prx5 is somewhat complex : high in mitochondria , some in peroxisome , and low in cytosol .
hence , the cellular abundance and broad distribution of 2-cys prxs mark them as a major antioxidant system in mammalian cells . beside their primary function as antioxidant enzymes , the observation that 2-cys prxs peroxidase activity can be readily inhibited by overoxidation of the active site cysteine residue ( cp ) and reactivated by sulfiredoxin - dependent reduction highlights novel and unforeseeable functions of these enzymes . in both in vitro enzyme reaction with high concentration of h2o2 and oxidatively - stressed cells ,
the cp - sulfenic acid at the active site of typical 2-cys prxs is overoxidized to sulfinic / sulfonic acids .
unlike bacterial homologs , the typical 2-cys prxs in eukaryotes have been characterized to show a structural feature that the resolving cysteine ( cr ) buries away in latent enzyme and then reacts with cp - sulfenic acid by local unfolding of the c - terminus .
it is therefore interpreted that such conformational change of the c - terminus in eukaryotic 2-cys prxs necessary for forming a disulfide linkage with the cp - sulfenic acid tolerates an additional reaction of the cp - sulfenic acid with the second molecule of h2o2 .
consequently , the 2-cys prxs can be inactivated by overoxidation during the reaction cycle and , if the inactive enzymes are accumulated , the local h2o2 concentration may be raised ( floodgate hypothesis ) .
subsequent studies state that the overoxidation of cp most probably corresponds to a gain of function of 2-cys prxs in eukaryotes .
the first surprising result is that the overoxidized 2-cys prxs are multimerized and function as a molecular chaperone to prevent unfolded proteins from irreversible aggregation .
hence , the evolution of the eukaryotic 2-cys prxs sensitive to overoxidation implies a highly efficient survival tactic in eukaryotes adapting oxidative stress .
recently , veal and her colleagues reported that the overoxidation of 2-cys prxs plays a role in cell survival other than as a molecular chaperone . in this study ,
the inactivation of 2-cys prx by overoxidation discharged a key coupling redox protein , thioredoxin , which in turn rescued other oxidized client proteins by reduction .
another compelling biological role of the 2-cys prx overoxidation is a correlation with circadian rhythm in normal physiology .
o'neill and reddy have shown that the overoxidation of 2-cys prxs exhibits a circadian oscillation with a period of about 24 hours in human red blood cells .
later , it turned out to be a transcription - independent circadian marker universally conserved from bacteria to eukaryotes . consequently , the intrinsic susceptibility of 2-cys prxs to inactivation by overoxidation is seemingly to be a part of the important redox mechanism in both normal and abnormal physiology .
in addition , a study using yeast mutant strains lacking multiple thiol peroxidases including all five prxs and three glutathione peroxidase genes suggests that the thiol peroxidases may transfer the ros signals to gene expression by transcriptional regulation .
therefore , in this review , we collect the evidence for specific signaling functions of typical 2-cys prxs with low km for h2o2 and discuss its implication as a conceptually new hub in signaling networks .
protein phosphorylation is one of the most important posttranslational modifications in the membrane receptor - mediated growth factor and cytokine signaling and as such modulates protein - protein interaction , enzyme activity , and protein stability and structure .
human genome encodes over 500 putative kinase genes and more than 150 protein phosphatases including dual - specificity phosphatases and protein tyrosine phosphatases ( ptp ) . with the exception of the eya subfamily ,
the sulfhydryl group is thus deprotonated to the thiolate anion at the physiological ph [ 15 , 16 ] , which renders it susceptible to oxidation by h2o2 in vitro and in vivo [ 17 , 18 ] . since h2o2 was proposed as a novel intracellular second messenger in the platelet - derived growth factor ( pdgf ) and epidermal growth factor ( egf ) signaling pathways [ 19 , 20 ] , the h2o2-mediated reversible oxidation of ptps has become an important regulatory mechanism controlling protein tyrosine phosphorylation [ 21 , 22 ] .
recently , plausible evidence also indicates that the protein kinases are redox - regulated by a reversible oxidation of the cysteine residues in the regulatory region , rather than on their active sites .
for example , ib kinases / ( ikk/ ) were shown to harbor a reactive cysteine between two serine residues , which are the dual phosphorylation sites critical for activation , in t - loop [ 2325 ] .
the ataxia - telangiectasia mutated ( atm ) kinase and a src kinase lyn were shown to be activated by a h2o2-mediated cysteine oxidation [ 26 , 27 ] .
such evidence concertedly indicates that the phosphorylation signaling network involves redox - regulated kinases / phosphatases and therefore it is associated with the dynamics of intracellular h2o2 level . in a live cell , the intracellular h2o2 level
is determined by balancing the h2o2 generators ( e.g. , mitochondria , oxidases , and heavy metals ) and antioxidants ( e.g. , catalase , glutathione peroxidases , and peroxiredoxins ) . among cellular peroxidases ,
in particular , the evidence indicates that the two cytosolic forms , prx1 and prx2 , are likely the key enzymes in the phosphorylation signaling pathway ( figure 1 ) .
the first indication of the signaling function of prx was made in 1998 and showed that the overexpression of prx1 and prx2 eliminated intracellular h2o2 increased by growth factors , such as pdgf - b and egf , and cytokine tumor necrosis factor ( tnf)- . since then , many investigations indicate the important regulatory role of prx1/2 in phosphorylation signaling .
the prx1 ablation was shown to result in the akt hyperactivation in h2o2-treated cells , but not in pdgf - treated cells .
prx1 interacted with phosphatase and tensin homolog ( pten ) in h2o2-treated cells and thus promoted the ras- or erbb2-drived cell transformation .
however , the function of prx2 as a signal regulator was initially proposed by the differential regulation of tnf--induced map kinase activation .
also , prx2 negatively regulates the pdgf - induced tyrosine phosphorylation in fibroblast and vascular smooth muscle cells . in this case , the deletion of prx2 , not prx1 , selectively increased the autophosphorylation of pdgfr only at two tyrosine sites ( y579 and y857 ) , which was not mimicked by addition of exogenous h2o2 .
such selective regulation was achieved by the stimulation - dependent interaction of prx2 and pdgfr proteins , which allowed the reactivation of a membrane - associated ptp .
this is the first report showing the selective action of endogenous h2o2 distinguished from the exogenous source of h2o2 .
recently , prx2 was also shown to preserve the vegfr2-dependent tyrosine phosphorylation in vascular endothelial cells by protecting the receptor from oxidative inactivation by both the endogenous and exogenous h2o2 .
this function appeared to be due to the colocalization of prx2 and vascular endothelial growth factor receptor-2 ( vegfr2 ) in endothelial caveolae .
although the source of endogenous h2o2 was not identified , it is an important finding that prx2 functions upstream of the receptor tyrosine kinase whose activity is regulated by an oxidation - sensitive cysteine residue .
the cytosolic 2-cys prxs are themselves linked to the phosphorylation networks as their activities are regulated by phosphorylation .
chang et al . reported that the 2-cys prxs contain the conserved cdk phosphorylation sequence ( thr - pro - arg - lys ) , and among them the prx1 and prx2 were indeed phosphorylated by cdk1/cdc2 .
although such threonine phosphorylation caused the loss of peroxidase activity of both 2-cys prxs in vitro , it was observed only in prx1 in vivo using the mitotic arrested hela cells .
other studies also showed that the prx1 threonine phosphorylation is mediated by serine / threonine kinase mst1/2 [ 33 , 34 ] .
similarly , this phosphorylation inactivated the peroxidase activity and therefore resulted in an increase in the intracellular h2o2 level .
in contrast , the serine phosphorylation of prx1 by a t - cell - originated protein kinase ( topk ) increased the peroxidase activity .
topk binds to and phosphorylates prx1 at ser in vitro and in human melanoma cells .
it is noteworthy that the activated topk colocalized with prx1 in nucleus , which is the first indication of nuclear prx1 .
later , both prx1 and prx2 were found in the nucleus and , particularly , prx2 protects the cancer cell death against dna damaging agents .
the threonine phosphorylation of prx2 correlates with an increased loss of dopaminergic neurons by mitochondrial damage .
interestingly , in this case , the phosphorylation was mediated by cdk5/p35 and increased in nigral neurons from postmortem tissue of parkinson 's disease patients .
related to parkinson 's disease , there was another interesting report that a mutation of leucine rich repeat kinase 2 ( lrrk2 ) , where glycine-2019 is mutated to serine , increased the phosphorylation of a mitochondrial prx3 .
the phosphorylation of prx3 was associated with the increased cell death in neuronal cells by a mitochondrial stress and significantly detected in parkinson 's disease patients with the lrrk2 mutation .
consequently , the phosphorylation - dependent inactivation of mitochondrial prx3 and cytosolic prx2 seems to be coordinately involved in the loss of dopaminergic neuronal cells by mitochondrial damage .
recently , prx1 was shown to be phosphorylated at tyr by protein tyrosine kinases , such as lck and abl , in vitro and in various mammalian cells treated with growth factors .
this evidence is significant in terms of that the inactivation of prx1 by phosphorylation in caveolae membrane microdomain could alter the local redox status .
although the authors showed the phosphorylated prx1 in the margin of healing wounds in c57bl/6 mice , the physiological relevance of the selective prx1 phosphorylation to wound healing process remained uncertain .
it is however clear that the phosphorylation - dependent inactivation takes a physiological advantage of the dynamic regulation linked to the intracellular kinase / phosphatase signaling network compared to prx inactivation by overoxidation , as the reversal by sulfiredoxin of the latter is a slow reaction requiring an atp energy demand [ 40 , 41 ] .
phosphorylation at thr and phosphorylation tyr have both been shown to regulate prx activity by a similar mechanism , potentially involving a perturbation of the active site conformation after the introduction of a negatively charged phosphate moiety at the vicinity of the active site cp residue [ 32 , 39 ] .
the crystal structure of prx1 also suggests that the introduction of negative charges may destabilize prx1 homodimer further causing the reduction of prx activity toward h2o2 . considering that the 2-cys prx isoforms are widely distributed in subcellular compartments , such modification - dependent inactivation of the 2-cys prxs may be an important mechanism in determining a localized elevation of h2o2 levels .
the reversible acetylation of protein lysine residues is an important posttranslational modification that regulates enzyme activity , protein - protein interaction , and protein conformation . the majority of the initial studies focused on the histone acetylation , which directly regulates gene transcription and chromatin remodeling .
since the microtubule - associated hdac6 and mitochondrial sirt3 were discovered [ 4446 ] , the reversible acetylation has been considered to be a general modification involved in the cellular signaling .
one study showed that h2o2 inhibits il-1-induced hdac2 activity in airway epithelial cells , which is associated with the tyrosine nitration of hdac2 .
another study showed that h2o2 and hypertrophic stimuli induce a cysteine oxidation on hdac4 in myocytes . upon oxidation ,
hdac4 forms an intramolecular disulfide linkage and then the oxidized hdac4 is exported to the cytoplasm . when the disulfide was reduced by trx1 ,
a member of class ii hdacs , sirt1 , was shown to be sensitive to oxidation , especially s - glutathionylation on the cys residue by s - nitrosoglutathione ( gsno ) .
interestingly , the gsno inhibited the resveratrol - stimulated , not the basal , sirt1 activity , which suggests that the redox - sensitive cys residue could be exposed to the modification upon activation .
the sirt3 knockout mice showed oxidative stress phenotype in skeletal muscle and its knockdown in cultured myoblasts increased the ros level .
many studies show that the 2-cys prx activity is regulated by acetylation ( figure 1 ) . a recent high - resolution mass spectrometric analysis combined with the stable isotope labeling by amino acids in cell culture ( silac ) revealed the lysine acetylation of prx enzymes in various cell types .
a previous study showed that the prx1 and prx2 were among the substrates of cytoplasmic hdac6 and their acetylation increased peroxidase activity and resistance to overoxidation .
it was shown that a lysine residue in the c - terminus of prx1 and prx2 enzymes ( lys197 in prx1 and lys196 in prx2 ) is a site of acetylation .
thus , although the molecular mechanism underlying the acetylation - dependent activity increase is currently unknown , it is possible that the c - terminal acetylation may influence the resolving step accompanied with a conformation change of the cr residue . in the case of prx2 ,
the lysine - independent acetylation at its demethionylated n - terminus conferred a resistance to overoxidation in hela cells treated with high concentrations of h2o2 .
it is noteworthy that the acetylation of 2-cys prxs increases the enzyme activity and protects against overoxidation in contrast to enzyme inactivation by phosphorylation .
although there is no evidence showing a direct regulatory role of 2-cys prxs in the lysine acetylation network , it will be interesting to investigate the mechanism of how the acetylation and deacetylation network is associated with 2-cys prxs in various subcellular compartments .
the role of ros in cell death has been a long - standing issue because mitochondria are the key players in both apoptotic and necrotic cell death pathways .
indeed , mitochondria are the site where the electron transport takes place and leakage of the high energy electrons from the electron carrier complexes can combine with molecular oxygen to produce ros .
higher organisms with an aerobic respiratory system have evolved apoptotic cell death programs utilizing mitochondrial proteins , which include cytochrome c [ 55 , 56 ] . in principle , the mitochondrial release of cytochrome c results in a disruption of the electron transport in the respiratory chain and causes an increase of mitochondrial ros via the leakage of high energy free electrons .
the resulting ros burst may oxidatively damage the cellular macromolecules , such as proteins , membrane lipids , and dna .
however , the evidence indicates that the mitochondrial ros is not a causative factor in apoptotic cell death , but rather it is the consequence of the disruption of mitochondrial transmembrane potential ( m ) .
the involvement of ros in the apoptotic death pathway could be challenged by the fact that the active site of caspase is a reactive cysteine residue , which can be inactivated by oxidation [ 5860 ] .
necroptosis , also called programmed necrosis , is a type of necrotic cell death involving the activation of death receptor but occurring independently of caspase activation .
it has been shown that activation of death receptors , such as the tnf- receptor ( tnfr)-1 and fas ( cd95 ) , induces necroptosis in some cell types [ 62 , 63 ] .
for example , mouse fibrosarcoma cells l929 underwent caspase - independent necrosis when stimulated with tnf- .
human jurkat t lymphoma cells deficient in fas - associated death domain ( fadd ) adaptor protein died via necrosis when death receptors , such as tnfr and fas , were activated in an rip1-dependent manner .
further evidence indicates that ros accumulates in a rip1 and fadd - dependent manner and is required for the necroptosis .
the activation of nadph oxidase-1 via rip1 is involved in the tnf--induced necrosis in l929 cells .
in addition , rip3 , which was shown to be the most essential factor for necroptosis [ 69 , 70 ] , was involved in the production of mitochondrial ros via energy metabolism .
the cell death studies by modulation of cellular antioxidant enzymes reveal a clear role of intracellular ros in apoptosis .
particularly , the 2-cys prxs play a regulatory role in apoptotic , not necrotic , cell death ( figure 2 ) .
prx1 was shown to protect lung cancer cells from radiation - induced apoptotic cell death by reducing jnk activation .
interestingly , prx1 prevented the jnk activation by retaining the jnk associated with glutathione s - transferase ( gst)-pi , but not through the peroxidase activity .
it was also shown that the expression of prx1 in dopaminergic neuronal cells inhibited 6-hydroxydopamine - induced apoptotic death by reducing the p38/caspase-3 activation .
the level of prx1 was obviously upregulated in human lung cancer patients and the prx1 knockdown in hepatocarcinoma cells accelerated the tnf - related apoptosis - inducing ligand ( trail)-induced cell death via caspase-8/-3 activation .
prx1 also mediated the disulfide - linked activation of the apoptosis signaling kinase ask1 by forming a mixed disulfide intermediate with ask1 in the peroxide - treated cells .
it has been shown that prx2 and prx3 reduce apoptotic cell death via mitochondrial - dependent intrinsic pathway [ 76 , 77 ] .
interestingly , the redox cycle of the prx3 activity shifted to the disulfide - containing oxidized state during fas - mediated apoptosis of jurkat and u937 monocytic cells .
collectively , the evidence related to the 2-cys prxs strongly indicates that ros is connected to the apoptotic cell death .
further exploration is needed to determine the molecular mechanism underlying antiapoptotic role of 2-cys prxs .
despite the 2-cys prx being a sophisticated peroxidase enzyme with a high affinity to h2o2 , recent studies also suggest that 2-cys prx can function as redox protein that regulates the activity of various client proteins by direct protein - protein interaction or interprotein disulfide linkage . in 1997
, it was reported that prx1 interacts with the sh3 domain of c - abl and inhibits its tyrosine kinase activity .
it was the first report showing that the 2-cys prx is one of the redox proteins capable of regulating a key signaling kinase .
subsequently , prx1 has been found to interact with the myc box ii ( mbii ) domain of c - myc by a yeast two - hybrid screen . by this interaction , prx1 contributed to an antioxidative stress function and it did also inhibit the c - myc - dependent target gene expression and tumorigenesis . park and
her colleagues showed that prx1 interacts with androgen receptor in various prostate cancer cell lines and gst - pi in lung cancer cell lines [ 72 , 82 ] .
the findings seem to be important in relation to the high prx1 expression in the prostate cancer patients .
another interesting result was that prx1 interacts and forms a mixed disulfide linkage with the gde2 activation in spinal motor neurons . in motor neuron progenitors
, prx1 promotes the gde2 activity to drive a neuronal differentiation by reducing an intramolecular disulfide linkage in the cytoplasmic tail of the transmembrane protein .
this evidence indicates that the prx1 can function as a protein disulfide reductase ( pdi ) .
it was shown that the oxidized prx4 transfers the disulfides to pdi [ 5 , 6 ] .
the prx4 reoxidation is achieved by metabolizing h2o2 produced by ero1 , which is known as the main er enzyme responsible for reoxidation of protein disulfide reductase .
this evidence defines a new role of prx4 in oxidative protein folding along with ero1 .
in contrast to the case of prx1 , the closest isoform prx2 has barely been shown to directly interact with any protein .
actually , few reports are stating that prx2 colocalizes and interacts with phospholipase d1 in phorbol ester - stimulated cells as well as interacts with the pdi family member , erp46 , when under its overoxidized form .
the in vitro activity assays showed that prx2 is less active as a peroxidase enzyme than prx1 [ 1 , 39 ] .
given the in vitro evidence that the 2-cys prxs is inactivated by overoxidation during the reaction cycle proportional to the enzyme activity , it is conceivable that prx1 is the peroxidase enzyme acting as the first line of antioxidant defense under h2o2 stress .
nonetheless , it turned out that prx2 is more susceptible for overoxidation in the animal cells under h2o2 stress than prx1 .
the same study shows that prx1 rather prefers to be tyrosine phosphorylated under h2o2 stress in vivo .
this discrepancy between in vitro and in vivo properties of prx1 and prx2 could be explained as a paradox : unlike the potential function assumed from the in vitro characterization , the prx2 can be the real peroxidase enzyme in the cells while the prx1 primarily functions as a redox regulator of diverse client proteins by interaction .
this idea is supported to some extent because it was observed that prx1 was more abundant in protein amount than was prx2 in certain cell types like fibroblasts and hela cells . in an effort to obtain a global picture of regulations by 2-cys prxs
, we finally produced a network model among typical 2-cys prxs using the pathway studio software .
we obtained the network relations for all four prxs in the knowledge base of pathway studio , which were built by text - mining of literature texts .
figure 3 shows the resulting network model where relations specific to each prx were located near the corresponding prx and entities involved in more than one prxs were positioned in the intervening space .
this network includes the direct interaction of 2-cys prxs and their client proteins as mentioned above .
as expected , it is evident that all four prxs are closely related to apoptosis and cell death , ros generation and oxidative stress , cell proliferation , growth , and differentiation .
this diagram also illustrates biological processes and functions specific to each prx or common between two prxs .
it can be readily seen that cytosolic enzymes prx1 and prx2 are related to cell survival via pten , tnf , map kinases , and parp1 .
overall , the network model emphasizes the importance of typical 2-cys prxs as hub molecules connecting cellular signaling pathways and biological processes .
four members of typical 2-cys prx subfamily are present in various cellular compartments , including cytosol , plasma membrane ( especially caveolae ) , nuclei , mitochondria , and endoplasmic reticulum .
the majority of the abundant 2-cys prx enzymes primarily function as general antioxidant systems that maintain the intracellular ros level within a safety zone in both normal and stressed cells . however , some part of the enzymes functions as the signal regulator at specific locations by modulating the local ros change or by regulating the activity of the interacting / neighboring proteins in a redox - dependent manner .
since h2o2 is an important second messenger in a signaling network , the discovery of the 2-cys prx function related to signal transduction should provide clues necessary to understand redox signaling architecture and further solve medical problems in ros - mediated chronic diseases .
Output:
| mammalian cells have a well - defined set of antioxidant enzymes , which includes superoxide dismutases , catalase , glutathione peroxidases , and peroxiredoxins .
peroxiredoxins are the most recently identified family of antioxidant enzymes that catalyze the reduction reaction of peroxides , such as h2o2 .
in particular , typical 2-cys peroxiredoxins are the featured peroxidase enzymes that receive the electrons from nadph by coupling with thioredoxin and thioredoxin reductase .
these enzymes distribute throughout the cellular compartments and , therefore , are thought to be broad - range antioxidant defenders .
however , recent evidence demonstrates that typical 2-cys peroxiredoxins play key signal regulatory roles in the various signaling networks by interacting with or residing near a specific redox - sensitive molecule .
these discoveries help reveal the redox signaling landscape in mammalian cells and may further provide a new paradigm of therapeutic approaches based on redox signaling . |
PubmedSumm118647 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: they range from the base composition to more complex features like periodicities , correlations , information content or isochore structure . a widespread feature among most eukaryotic genomes are long - range correlations in base composition ( 16 ) , characterized by an asymptotic power - law decay c(r )
r of the correlation function
1c(r)n{a , c , t , g}[prob(ai = ai+r = n)prob(ai = n)2 ]
along the dna sequence a=a1, ,an .
amplitudes and decay exponents differ considerably between different species and even between different genomic regions of the same species ( 6 ) .
the widespread presence of long - range correlations raises the question if they need to be incorporated into an accurate null model of eukaryotic dna , reflecting our assumptions about the background statistical features of the sequence under consideration ( 7 ) .
the need for a realistic null model arises from the fact that the statistical significance of a computational prediction derived by bioinformatics methods is often characterized by a p - value , which specifies the likelihood that the prediction could have arisen by chance .
popular null models are random sequences with letters drawn independently from an identical distribution , or kth order markov models specifying the transition probabilities p(ai+1aik+1 , , ai ) in a genomic sequence ( 8)
. however , both models are incapable of incorporating long - range correlations in the sequence composition .
in corgen we use a dynamical model that was found to efficiently generate such long - range correlated sequences ( 9 ) .
recent findings already demonstrated that long - range correlations have strong influence on significance values for several bioinformatics analysis tools .
for instance , they substantially change the p - values of sequence alignment similarity scores ( 10 ) and contribute to the problem that computational tools for the identification of transcription factor binding sites perform more poorly on real genomic data compared to independent random sequences ( 11 ) . in this paper
we present corgen , a web server that measures long - range correlations in dna sequences and can generate random sequences with the same ( or user - specified ) correlation and composition parameters . these sequences can be used to test computational tools for changes in prediction upon the incorporation of genomic correlations into the null model .
several techniques for the generation of long - range correlated sequences have been proposed so far ( 1214 ) . here , we use a simple dynamical method based on single site duplication and mutation processes ( 15 ) .
this dynamics is an instance of a , so called , expansion - randomization system , which recently have been shown to constitute a universality class of dynamical systems with generic long - range correlations ( 9,16 ) .
in contrast to any of the methods ( 1214 ) , the duplication - mutation model combines all of the following advantages : ( i ) exact analytic results for the correlation function of the generated sequences have been derived ; ( ii ) the method allows to generate sequences with any user - defined value of the decay exponent > 0 , desired gc - content g , and length n ; ( iii ) the correlation amplitude is high enough to keep up with strong genomic correlations and can easily be reduced to any user - specified value ; ( iv ) the dynamics can be implemented by a simple algorithm with runtime o(n ) ; ( v ) the duplication and mutation processes are well known processes of molecular evolution . in corgen
the dynamics of the model is then defined by the following update rules :
a random position j of the sequence is drawn.the nucleotide aj is either mutated with probability pmut , or otherwise duplicated , i.e. a copy of aj is inserted at position j + 1 thereby increasing the sequence length by one .
the nucleotide aj is either mutated with probability pmut , or otherwise duplicated , i.e. a copy of aj is inserted at position j + 1 thereby increasing the sequence length by one .
if the site aj = x has been chosen to mutate , it is replaced by a nucleotide y with probability
prob(xy)={(1g)/2y = a , tg/2y = c , g .
this assures a stationary gc - content g. extending the results derived in ( 16 ) it can analytically be shown that the correlation function of sequences generated by this dynamics is a euler beta function with c(r ) r in the large r limit . by varying the mutation probability pmut ,
the decay exponent of the long - range correlations can be tuned to any desired positive value , as it is determined by = 2pmut/(1pmut ) .
the correlations c(r ) of the generated sequences define the maximal amplitude obtainable by our dynamics for the specific settings of and g. however , this amplitude can easily be decreased by the following procedure : after the sequence has reached its desired length , the duplication process is stopped
. subsequent mutation of m randomly drawn sites using the transition probabilities defined in ( 2 ) will uniformly decrease the correlation amplitude to c(r ) = c(r)exp(2m / n ) without changing the exponent and the gc - content g ( 9 ) .
we use a queue data structure to store the sequences , since this allows for a fast implementation of a nucleotide duplication in runtime o(1 ) .
the web server corgen offers three different types of services : ( i ) measuring long - range correlations of a given dna sequence , ( ii ) generating long - range correlated random sequences with the same statistical parameters as the query sequence and ( iii ) generating sequences with specific user - defined long - range correlations .
the first two tasks require the user to upload a query dna sequence in fasta or embl format . for long - range correlations to be detectable ,
the sequences need to be sufficiently long ( we recommend at least 1000 bp ) .
the distance interval where a power - law is fitted to the measured correlation function can be specified by the user . upon submission of a query dna sequence
, corgen will generate plots with the measured gc - profile and correlation function , as defined by equation 1 .
the user can specify a distance interval where a power - law should be fitted to the measured correlation function .
the obtained values for the decay exponent and the correlation amplitude will be reported by corgen .
if a long - range correlated random sequence with the same statistical features in the specified fitting interval has been requested , its corresponding composition and correlation plots will also be shown .
if large ensembles of the generated sequences are needed , independent realizations of the sequences can directly be obtained via non - interactive network clients , e.g. wget .
corgen can also be used to generate long - range correlated random sequences with specific user - defined correlation parameters . in this case
, the user needs to specify the decay exponent , the correlation amplitude c(r ) at a reference distance r , the desired gc - content g and the sequence length .
notice that there is a generic limit for the correlation amplitude depending on the values of and g. as a typical example , the measurement of c(r ) for human chromosome 22 takes 65 s , while a random sequence of length 1 mb with the same correlation parameters can be generated in < 5 s.
in the following , we want to exemplify a possible application of corgen related to the problem that long - range correlations significantly affect the score distribution of sequence alignment ( 10 ) .
imagine one aligns a 100 bp long query sequence to a 1 mb region on human chromosome 22 in order to detect regions of distant evolutionary relationship .
the alignment algorithm reports a poorly conserved hit with a p - value of 10 calculated from the standard null model of a random sequence with independent nucleotides .
however , the user does not trust this hit and wants to test whether it might be an artifact of long - range correlations in human chromosome 22 . as a first step ,
the correlation analysis service provided by corgen is used to assess whether such correlations are actually present in the chromosomal region of interest .
it turns out that a clear power - law with = 0.359 can be fitted to c(r ) , as is shown in the top part of figure 1 .
the next step is to retrieve an ensemble of random sequences generated by corgen with the same correlation and composition parameters as the 1 mb region of chromosome 22 ( large ensembles can also be retrieved by non - interactive network clients ) .
for one such realization the measured gc - profile and correlation function are shown in the bottom part of figure 1 .
the 100 bp query sequence is then aligned against each realization of the ensemble in order to obtain the by chance expected distribution of alignment scores under the more sophisticated null model incorporating the genomic long - range correlations . as has been shown in ( 10 ) , for
the measured correlation parameters this can increase the p - value of a randomly predicted ( false - positive ) hit by more than one order of magnitude . in conclusion
corgen can therefore help to reduce the often encountered high false - positive rate of bioinformatics analysis tools .
the two plots in the top part show the measured gc - profile ( left ) and correlation function ( right ) of the chromosomal region . in the double - logarithmic correlation graph , power - law correlations c(r ) r show up as a straight line with slope . the fitting has been performed in the range 10 < r < 10 000 , and the obtained parameters are = 0.359 and c ( 10 ) = 0.0234 ( green line ) . a corresponding random sequence of length 1 mb with the measured long - range correlation parameters and average gc - content of the query sequence has been generated and can be downloaded by the user .
its composition profile and correlation function are shown in the two plots at the bottom .
Output:
| corgen is a web server that measures long - range correlations in the base composition of dna and generates random sequences with the same correlation parameters .
long - range correlations are characterized by a power - law decay of the auto correlation function of the gc - content .
the widespread presence of such correlations in eukaryotic genomes calls for their incorporation into accurate null models of eukaryotic dna in computational biology . for example
, the score statistics of sequence alignment and the performance of motif finding algorithms are significantly affected by the presence of genomic long - range correlations .
we use an expansion - randomization dynamics to efficiently generate the correlated random sequences .
the server is available at |
PubmedSumm118648 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: congenital dermal sinus ( cds ) is a congenital anomaly that develops anywhere in the midline along the neuraxis1 ) .
cds belongs to a group of disorder called occult spinal dysraphism in which skin covers most of the defect of the neuraxis and overlying tissues , except for a small skin ostium of the dermal sinus tract . in the lumbosacral area ,
the skin ostium of the dermal sinus tract is usually situated above the gluteal folds , which is an important clue for differentiating it from benign sacrococcygeal dimples2 ) .
however , the clinical importance of cds is that some patients with the anomaly can develop severe infection of the central nervous system , such as bacterial meningitis and spinal cord abscesses , through the dermal sinus tract3 ) .
therefore , pediatricians should be alert for the possibility of cds when examining a dimple in the midline of scalp and back .
overlooking cds or misdiagnosing the anomaly as a benign sacrococcygeal dimple may lead to a catastrophic infection and cause serious neurological deficits4 ) .
we encountered a 12-month - old girl who presented with a pyomyelia in the whole spinal cord .
further evaluation showed a small skin ostium in the upper sacral area and a cds leading into the spinal canal .
unfortunately , a detailed history report revealed that the skin ostium was detected early in her neonatal period by the parents , but they thought it was a benign skin lesion with little clinical importance . despite surgical evacuation of the abscess and infection control , the patient showed grave neurological deficits .
this case emphasizes the crucial importance of gaining knowledge of and directing clinical attention to differentiating a potentially life - threatening anomaly from benign lesions , and primary physicians are urged to be vigilant in understanding and diagnosing cds .
a 12-month - old girl visited the emergency room with a high fever and progressive paraparesis .
the patient had normal development and began to walk at approximately 10 months of age .
she had developed a fever of up to 39.5 15 days prior to the visit .
while visiting a local clinic , she was diagnosed with pharyngitis and received antibiotics and antipyretics .
five days ago , her high fever returned again . from then , she intermittently showed lethargic symptoms and was unwilling to walk .
she received additional examinations for infectious disease and supportive treatment for days , and finally , the local physician decided to transfer her to our hospital , when she showed overt paraparesis . upon arrival at the emergency room , she was acutely ill - looking and lethargic .
her vital signs were as follows : heart rate 137 beats / min ; blood pressure 123/56 mm hg ; respiratory rate 28 breaths / min ; body temperature 38.6. she was alert but exhibited quadriparesis .
her motor grade was i / i for upper extremities and 0/0 for lower extremities .
a palpable mass was found in her abdomen , which was determined to be a distended bladder . there was a tiny dimple in the midline of the upper sacral area ( fig .
it was located above the gluteal folds , approximately 6 cm away from the anus .
a small amount of whitish thick discharge was squeezed from the dimple by manual pressure .
a laboratory examination revealed blood leukocytosis ( 15500/l ) , decreased hemoglobin ( 10.9 g / dl ) , decreased hematocrit ( 31.6% ) , and elevated c - reactive protein ( 5.83 mg / dl ) .
the febrile illness and rapidly ascending quadriparesis indicated an infectious disease of the central nervous system involving the spinal cord . the high - lying midline skin dimple with discharge added suspicion of an underlying infected dermoid .
a detailed history was collected and revealed that her parents had found the skin dimple during her neonatal period , but they thought it was an innocent lesion that did not require further investigation . spinal magnetic resonance imaging ( mri ) was immediately obtained ( fig .
2 ) . the mri revealed diffuse high signal intensity along the spinal cord up to the medulla oblongata .
an enlarged central canal and thick gadolinium - enhancement of the lining up to the t1 level was observed .
a dermal sinus tract ran obliquely upward from the conus at the s3 level to the skin .
there were multiple dermoid cysts along the sinus tract entering the dural sac through the fascial and bone defect ( fig .
3 ) . after a multi - level laminectomy , the dural sac was opened and a thickened spinal cord was observed .
a dorsal midline myelotomy was made and noxious green - colored pus was discharged from the abscess .
later , peptoniphilus asaccharolyticus and an unidentified anaerobic rod were isolated from the pus and we added metronidazole to the drug regimen .
serial spinal mris showed gradual shrinkage of the residual t2 high signal intensity and enhancement in the spinal cord . in this time period
she can move her legs slightly , but she is still wheelchair - bound and needs cic for bladder care .
cds is a rarely encountered anomaly in clinical practice . because of its low incidence rate ,
the sinus tract can be a potential route of a life - threatening infection to the central nervous system ; thus , cds requires early detection and surgical treatment .
therefore , clinicians should be alert when examining skin dimples in the midline on the back .
one major obstacle to correctly diagnosing cds is that there exists a benign entity called a sacrococcygeal dimple , and its incidence rate is far higher than that of cds6 ) .
they are typically small ( < 5 mm in width ) and are located in the midline in the gluteal folds within 2.5 cm from the anus .
it is not accompanied skin stigmata , such as hemangiomas , elevated masses , tails , or hairy patches .
kriss and desai7 ) reported that none of the 180 simple dimples satisfying these criteria were associated with occult spinal dysraphism in imaging studies .
atypical dimples located higher on the back , although not pathognomonic of occult spinal dysraphism , are of high risk and warrant further evaluation . sometimes , whether a skin dimple is benign is not easy to determine by inspection alone6 ) . in such cases ,
the skin dimple was clearly located high on the back away from the coccygeal area .
unfortunately , there was a chance to detect the presence of cds and enough time to prevent the catastrophe .
currently , primary physicians are keen to diagnose hidden anomalies such as occult spinal dysraphism . knowledge and precautions against such a disorder are common even among the general public . however , erroneous information is still widespread and a decision - making mistake may lead to irreversible damage to the patient4 ) .
interestingly , all the patients were previously examined by medical personnel ( family doctor , pediatrician , or general practitioner ) and they made no action or gave just empirical treatment with antibiotics before significant neurological deficits or meningitis developed .
inspection of the whole body is a routine for neonates and midlines in the scalp and back should be included in this procedure . for any atypical dimples ,
elton and oakes5 ) further emphasized that surgical exploration is mandatory for dermal sinus tracts located above the gluteal folds .
spinal intramedullary abscesses are a severe complication of cds . among the various septic presentations of cds
, meningitis is the most common and spinal intramedullary abscess is the least common finding3 ) .
prompt surgical drainage of the abscess cavity through a dorsal midline myelotomy is the best choice to control the infection and to enhance functional recovery . in the literature
, some patients attained complete recovery of neurological functions , but others had only a partial improvement after surgery11 ) .
the outcome may depend on the degree of septic involvement of the spinal cord and the time to diagnosis and surgical intervention . in the series of ramnarayan et al.10 ) , all patients over the age of 1 year had purulent infection or neurological deficits at presentation , and surgical morbidity paralleled the time interval to definitive treatment .
a delay in the proper diagnosis from the onset of fever and gait disturbance may prevent optimal recovery despite emergency surgical intervention .
failure to detect a csd may lead to catastrophic infection in the central nervous system .
an early diagnosis and prompt surgical intervention are required before the onset of severe infection .
clinicians should be alert to any atypical - looking skin dimples in the midline of infants and children .
Output:
| congenital dermal sinus ( cds ) is a type of occult spinal dysraphism characterized by a midline skin dimple . a 12-month - old girl presented with fever and ascending quadriparesis .
she had a midline skin dimple in the upper sacral area that had been discovered in her neonatal period .
imaging studies revealed a holocord intramedullary abscess and cds .
overlooking cds or misdiagnosing it as benign sacrococcygeal dimple may lead to catastrophic infection and cause serious neurological deficits .
therefore , further imaging work - up or consultation with a pediatric neurosurgeon is recommended following discovery of any atypical - looking dimples in the midline . |
PubmedSumm118649 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: epithelial ovarian cancer accounts for 25% of all malignancies affecting the female genital tract , and is the most lethal gynecologic malignancy . in 2012 , there will be an estimated 22,280 new ovarian cancer cases in the us , with 15,500 deaths.1 advanced epithelial ovarian cancer is traditionally managed with cytoreductive surgery , followed by combination platinum and taxane chemotherapy.2 patients with advanced disease who undergo successful cytoreductive surgery with no gross residual disease have a median survival of just over 5 years after completion of adjuvant chemotherapy.3 however , despite aggressive treatment , the majority of these patients develop recurrent cancer , with selection of chemotherapy - resistant clones.4 the subset of patients that develops recurrent disease comprises a population that traditionally faces extended exposure to multiple cytotoxic chemotherapy regimens , dictated by their disease - free interval.58 throughout this period , management of disease - associated morbidities becomes a priority in an effort to improve quality of life .
malignant ascites , which affects approximately two - thirds of patients with epithelial ovarian , primary peritoneal , and fallopian tube cancer is common , and to date few effective therapies have been identified.9 importantly , ascites is associated with troublesome symptoms , including abdominal pressure and distension , dyspnea , bloating , pelvic pain , and bowel / bladder dysfunction.10 malignant ascites is defined by the national cancer institute as an accumulation of fluid containing cancer cells in the abdomen.11 unlike other solid malignancies , where ascites portends a universally poor prognosis , patients with epithelial ovarian cancer and ascites at the time of diagnosis can expect 5-year survival rates approaching 40%.11,12 this discrepancy is largely attributable to the biology of ovarian cancer , and subsequent etiology of abdominal fluid accumulation .
specifically , malignant ascites in patients with epithelial ovarian cancer is thought to be attributable to lymphatic obstruction , increased vascular permeability release of inflammatory cytokines , and a direct increase of fluid production by the cancer cells lining the peritoneal cavity.13,14 upfront treatment of patients with advanced epithelial ovarian cancer , irrespective of the presence or absence of ascites , relies on a combination of aggressive cytoreductive surgery and adjuvant chemotherapy .
the goal of surgical cytoreduction is to reduce disease burden to 1 cm ( defined as optimal cytoreduction by the gynecologic oncology group ) . as a result of optimal cytoreduction
, despite improvement in surgical management , only a small fraction of patients are cured following primary surgery and chemotherapy , with greater than 75% experiencing disease recurrence .
repeat attempts at surgical excision are only performed in selected patients with prolonged disease - free intervals , localized disease recurrence , and good performance status .
accumulation of ascites affects patients with progressive disease or treatment failure , and must be managed in order to maintain overall quality of life.15 historically , malignant ascites in patients with epithelial ovarian cancer was treated utilizing diuretics , salt restriction , and intraperitoneal administration of sclerosing agents and radioactive isotopes.16,17 patients with malignant ascites secondary to epithelial ovarian cancer rarely suffer from fluid accumulation due to intraparenchymal liver metastasis , and portal hypertension is rarely identified .
rather , these patients traditionally exhibit reduced intravascular volume , making use of diuretics an unattractive option.18 with respect to the use of radioactive isotopes , poor tumor penetration and intestinal toxicity ( necrosis and perforation ) due to loculations and prolonged exposure have caused them to fall out of favor .
limited success rates , in combination with significant side effects , have resulted in infrequent use of these modalities .
mechanical drainage of accumulated ascetic fluid via therapeutic paracentesis results in relief in up to 90% of patients.19 however , recurrence / reaccumulation of ascites is common , and multiple paracenteses are required , with their associated risks of pain , visceral perforation , infection , and formation of hematoma.11,20 furthermore , these patients are likely to have intra - abdominal adhesions as a result of extensive surgical cytoreduction , and the resultant fluid loculations limit the therapeutic benefit derived.21 alternatively , placement of permanent intra - abdominal drains and peritoneovenous shunts has been explored .
experience with these modalities has been poor , with blockage of the shunt , infectious morbidity , as well as embolization and implantation of tumor cells in distant organs reported to be relatively common complications.17,2225 given the above , exploration of innovative approaches for the treatment of malignant ascites in patients with advanced epithelial ovarian cancer has been a clinical priority . with advances in our understanding of cancer biology , novel therapeutic targets have been identified . specifically , the relationship between angiogenesis and epithelial ovarian cancer has been elucidated over the last decade , and strategies developed to interfere with this process have shown promise in the control of ascites associated with epithelial ovarian cancer .
this mini review article discusses the role of emerging therapies targeting angiogenesis in the management of ascites , and summarizes the currently available data in the literature .
under normal homeostatic conditions , excluding wound healing and embryonic development , a balance exists between proangiogenic and antiangiogenic signals , resulting in a quiescent vascular environment .
however , within the tumor microenvironment , aberrant signaling has been shown to favor the proangiogenic cascade , resulting in formation of new vessels.26,27 the formation of new blood vessels , a process termed angiogenesis , is essential for tumor growth beyond 12 mm .
this process is mediated via the vascular endothelial growth factor ( vegf ) family of growth factors and receptors , and is believed to be essential for tumor growth and ascites formation .
furthermore , these tumor vessels , formed under the influence of vegf , are disorganized , tortuous , and leaky.28 inhibition of vegf - mediated signaling leads to normalization of this tumor vasculature , as well as improved oxygen , nutrient and chemotherapy delivery , and is believed to result in increased tumor toxicity and decreased formation of ascites fluid.8 vegf expression has been repeatedly demonstrated in epithelial ovarian cancer tissue specimens , and the degree of expression of vegf and its receptors has been shown to correlate with a poor prognosis.29,30 vegf - a ( commonly known and referred to as vegf ) was first identified and cloned in 1989.31 in a series of molecular biology and animal model studies , vegf was noted to be a potent mitogen for endothelial cells in vitro and acted as an angiogenic molecule in vivo .
in addition to vegf , the vegf family is composed of vegf - b , vegf - c , vegf - d , vegf - e , and the placental growth factors , plgf-1 and plgf-2.3234 the most important member of this group is vegf itself , which appears to play a principal role in angiogenesis .
vegf binds to and interacts with a series of receptor tyrosine kinases known as vegfr-1 , vegfr-2 , and vegfr- 3 , as well as accessory receptors known as neuropilins.35 it appears that signal transduction through vegfr-2 mediates the permeability actions of vegf , as evidenced by the fact that vegfr-2 gene knockout mice fail to develop vasculature and have sparse endothelial cells.36 it is hypothesized that as cancerous cells multiply and the tumor mass grows , there is secretion of vegf , promoting neovascularization , allowing for nutrient delivery , and facilitating metastasis . in cases of
disseminated intra - abdominal metastatic disease , both increased production of peritoneal fluid by the cancer cells , and increased microvascular permeability result in significant ascites .
in addition , investigators have shown increased vegf protein levels in malignant ascites compared with levels in nonmalignant cirrhotic controls.37
given the apparent dependence of ascites formation on abnormal tumor vascularity and permeability , it was hypothesized that vegf inhibitors would show efficacy in the treatment of ascites associated with ovarian cancer ( figure 1 ) . in preclinical nude mouse models of advanced ovarian cancer , inhibition of vegf signaling was associated with a marked decrease in ascites formation and tumor burden.3840 furthermore , it has been shown that malignant effusions derived from tumorbearing mice and guinea pigs contain high concentrations of vegf.41 vegf production by cancer cells has been shown to correlate directly with tumor - cell induced production of ascites in animal models.41 strikingly , direct transfection of mouse peritoneum with vegf alone is sufficient to cause accumulation of peritoneal effusions .
this strong preclinical evidence catalyzed the investigation of bevacizumab for the palliation of symptomatic ascites in patients with heavily pretreated recurrent ovarian carcinoma ( table 1).42 numnum et al described four patients with recurrent ovarian cancer and ascites requiring frequent paracentesis who were treated with intravenous bevacizumab at a dose of 15 mg / kg every 3 weeks . all four patients demonstrated symptomatic relief of ascites , with manageable toxicity .
no therapeutic paracenteses were required after initiation of treatment with bevacizumab ( follow - up of up to 6 months).42 in an analogous manner , hamilton et al described a case report detailing the impact of intraperitoneal bevacizumab ( 5 mg / kg ) on severe symptomatic ascites in an elderly patient with advanced , recurrent ovarian cancer and very poor functional status.43 the authors reported a dramatic improvement in ascites and quality of life parameters following two doses .
two additional case reports described the off - label use of bevacizumab in 10 patients with refractory ascites and significant disease burden.44 relief of ascites was seen in all subjects , lasting 26 months.41 the largest of these reports , described by el shami et al61 investigated the efficacy and safety of bevacizumab ( 5 mg / kg administered intraperitoneally every 4 weeks ) in nine patients with refractory ascites secondary to colorectal , breast , uterine , and ovarian cancer.41 remarkably , the malignant ascites resolved in all treated patients after a single dose , without reaccumulation over a median observation period of more than 2 months .
vegf - trap , a fusion protein that prevents vegf receptor binding , has also been studied in the treatment of refractory ascites .
in contrast with the antibody - based vegf binding strategy used by bevacizumab , vegf - trap , or aflibercept , incorporates the second binding domain of the vegfr-1 receptor and the third domain of the vegfr-2 receptor ( figure 2).45 by fusing these extracellular protein sequences to the fc segment of a human igg backbone , developers created a chimeric protein with a very high vegf binding affinity , binding all isomers of the vegf - a family.45,46 of note , it has also been shown to bind vegf - b and placental growth factor , with uncertain clinical implications .
preclinical xenograft animal models have shown that vegf - trap is effective in inhibiting tumor growth and angiogenesis , reducing blood vessel density , inhibiting metastasis , and improving survival.38,47,48 hu et al investigated the impact of vegf - trap on ascites formation in a mouse model of ovarian cancer.49 following intraperitoneal administration of vegf - trap and paclitaxel , complete resolution of ascites was noted , with a 98% reduction in tumor burden .
tumor vessel imaging showed sparse , short vessels in treated mice as compared with controls , in which vessels were numerous , irregular , tortuous , and leaky.49 in 2003 , byrne et al reported that single - agent aflibercept significantly reduced both ascites and tumor burden in experimental models of ovarian cancer.38 the safety and tolerability of vegf - trap were evaluated in a phase i clinical trial conducted by lockhart et al.50 a total of 47 patients ( 14 of whom had ovarian , peritoneal , or fallopian tube cancer ) were enrolled from two institutions .
the dose ranged from 0.3 mg / kg to 7.0 mg / kg given intravenously every 2 weeks .
the most common adverse events were fatigue , nausea , and vomiting . within this cohort ,
three partial responses were observed according to recist ( response evaluation criteria in solid tumors ) criteria , one at the 3.0 mg / kg and two at the 7.0 mg / kg dose level .
the authors concluded that vegf - trap , when administered intravenously , was well tolerated at the dose levels tested.50 several single - agent and combination phase ii clinical trials have explored the safety and efficacy of vefg - trap in the treatment of ascites associated with advanced solid tumors , including ovarian cancer.51,52 two recently published trials investigated the use of vegf - trap in the treatment of advanced epithelial ovarian cancer and symptomatic malignant ascites .
colombo et al enrolled 16 patients with advanced chemoresistant epithelial ovarian cancer and symptomatic malignant ascites into an open - label phase ii trial assessing the efficacy and safety of aflibercept.53 patients who required 3 previous paracenteses at 14 paracenteses per month received intravenous aflibercept at a dose of 4 mg / kg every 2 weeks . the primary endpoint was repeat paracentesis response rate , with response defined as at least a two - fold increase in time to repeat paracentesis compared with the baseline interval .
ten of the 16 enrolled patients achieved a response ; the repeat paracentesis response rate was 62.5% ( 95% confidence interval 35.484.8 , table 2 ) in these patients .
aflibercept was considered effective based on a hypothesis that the repeat paracentesis response rate was 60% .
median time to repeat paracentesis was 76.0 days ( 95% confidence interval 64.0178.0 ) , which was 4.5 times longer than the baseline interval ( 16.8 days , figure 4 ) .
adverse events reported as part of the study included hypertension ( seven patients ) , headache , anorexia , and dysphonia ( three patients each).53 only two subjects experienced grade 3/4 treatment - related adverse events , ie hypertension and weight loss , and one patient developed intestinal perforation . a similar study conducted by gotlieb et al specifically explored treatment of malignant ascites in patients with advanced epithelial ovarian cancer using aflibercept.54 in this double - blind , placebo - controlled ,
parallel - group , phase ii study , patients with advanced chemoresistant ovarian cancer and recurrent symptomatic malignant ascites were randomly assigned to receive either intravenous aflibercept ( 4 mg / kg every 2 weeks ) or placebo , stratified according to time interval ( 2 weeks versus > 2 weeks ) between the two most recent paracenteses before randomization.54 the primary efficacy endpoint was time to repeat paracentesis .
a total of 55 patients with a median of four ( range 211 ) previous lines of chemotherapy were randomly assigned to receive placebo ( n = 26 ) or aflibercept ( n = 29 ) . mean time to repeat paracentesis was significantly longer with aflibercept than with placebo ( 55.1 versus 23.3 days ; difference 31.8 days , 95% confidence interval 10.653.1 ; p = 0.0019 ) .
notably , in the aflibercept group , two patients did not need a repeat paracentesis during six months of double - blind treatment . in this subset of heavily pretreated patients with advanced ovarian cancer , three gastrointestinal perforations
were noted in the aflibercept group , and one intestinal fistula was identified in the placebo group .
given the apparent dependence of ascites formation on abnormal tumor vascularity and permeability , it was hypothesized that vegf inhibitors would show efficacy in the treatment of ascites associated with ovarian cancer ( figure 1 ) . in preclinical nude mouse models of advanced ovarian cancer , inhibition of vegf signaling was associated with a marked decrease in ascites formation and tumor burden.3840 furthermore , it has been shown that malignant effusions derived from tumorbearing mice and guinea pigs contain high concentrations of vegf.41 vegf production by cancer cells has been shown to correlate directly with tumor - cell induced production of ascites in animal models.41 strikingly , direct transfection of mouse peritoneum with vegf alone is sufficient to cause accumulation of peritoneal effusions .
this strong preclinical evidence catalyzed the investigation of bevacizumab for the palliation of symptomatic ascites in patients with heavily pretreated recurrent ovarian carcinoma ( table 1).42 numnum et al described four patients with recurrent ovarian cancer and ascites requiring frequent paracentesis who were treated with intravenous bevacizumab at a dose of 15 mg / kg every 3 weeks . all four patients demonstrated symptomatic relief of ascites , with manageable toxicity .
no therapeutic paracenteses were required after initiation of treatment with bevacizumab ( follow - up of up to 6 months).42 in an analogous manner , hamilton et al described a case report detailing the impact of intraperitoneal bevacizumab ( 5 mg / kg ) on severe symptomatic ascites in an elderly patient with advanced , recurrent ovarian cancer and very poor functional status.43 the authors reported a dramatic improvement in ascites and quality of life parameters following two doses .
two additional case reports described the off - label use of bevacizumab in 10 patients with refractory ascites and significant disease burden.44 relief of ascites was seen in all subjects , lasting 26 months.41 the largest of these reports , described by el shami et al61 investigated the efficacy and safety of bevacizumab ( 5 mg / kg administered intraperitoneally every 4 weeks ) in nine patients with refractory ascites secondary to colorectal , breast , uterine , and ovarian cancer.41 remarkably , the malignant ascites resolved in all treated patients after a single dose , without reaccumulation over a median observation period of more than 2 months .
vegf - trap , a fusion protein that prevents vegf receptor binding , has also been studied in the treatment of refractory ascites . in contrast with the antibody - based vegf binding strategy used by bevacizumab , vegf - trap , or aflibercept ,
incorporates the second binding domain of the vegfr-1 receptor and the third domain of the vegfr-2 receptor ( figure 2).45 by fusing these extracellular protein sequences to the fc segment of a human igg backbone , developers created a chimeric protein with a very high vegf binding affinity , binding all isomers of the vegf - a family.45,46 of note , it has also been shown to bind vegf - b and placental growth factor , with uncertain clinical implications .
preclinical xenograft animal models have shown that vegf - trap is effective in inhibiting tumor growth and angiogenesis , reducing blood vessel density , inhibiting metastasis , and improving survival.38,47,48 hu et al investigated the impact of vegf - trap on ascites formation in a mouse model of ovarian cancer.49 following intraperitoneal administration of vegf - trap and paclitaxel , complete resolution of ascites was noted , with a 98% reduction in tumor burden .
tumor vessel imaging showed sparse , short vessels in treated mice as compared with controls , in which vessels were numerous , irregular , tortuous , and leaky.49 in 2003 , byrne et al reported that single - agent aflibercept significantly reduced both ascites and tumor burden in experimental models of ovarian cancer.38 the safety and tolerability of vegf - trap were evaluated in a phase i clinical trial conducted by lockhart et al.50 a total of 47 patients ( 14 of whom had ovarian , peritoneal , or fallopian tube cancer ) were enrolled from two institutions .
the dose ranged from 0.3 mg / kg to 7.0 mg / kg given intravenously every 2 weeks .
the most common adverse events were fatigue , nausea , and vomiting . within this cohort ,
three partial responses were observed according to recist ( response evaluation criteria in solid tumors ) criteria , one at the 3.0 mg / kg and two at the 7.0 mg / kg dose level .
the authors concluded that vegf - trap , when administered intravenously , was well tolerated at the dose levels tested.50 several single - agent and combination phase ii clinical trials have explored the safety and efficacy of vefg - trap in the treatment of ascites associated with advanced solid tumors , including ovarian cancer.51,52 two recently published trials investigated the use of vegf - trap in the treatment of advanced epithelial ovarian cancer and symptomatic malignant ascites .
colombo et al enrolled 16 patients with advanced chemoresistant epithelial ovarian cancer and symptomatic malignant ascites into an open - label phase ii trial assessing the efficacy and safety of aflibercept.53 patients who required 3 previous paracenteses at 14 paracenteses per month received intravenous aflibercept at a dose of 4 mg / kg every 2 weeks .
the primary endpoint was repeat paracentesis response rate , with response defined as at least a two - fold increase in time to repeat paracentesis compared with the baseline interval .
ten of the 16 enrolled patients achieved a response ; the repeat paracentesis response rate was 62.5% ( 95% confidence interval 35.484.8 , table 2 ) in these patients .
aflibercept was considered effective based on a hypothesis that the repeat paracentesis response rate was 60% .
median time to repeat paracentesis was 76.0 days ( 95% confidence interval 64.0178.0 ) , which was 4.5 times longer than the baseline interval ( 16.8 days , figure 4 ) .
adverse events reported as part of the study included hypertension ( seven patients ) , headache , anorexia , and dysphonia ( three patients each).53 only two subjects experienced grade 3/4 treatment - related adverse events , ie hypertension and weight loss , and one patient developed intestinal perforation .
a similar study conducted by gotlieb et al specifically explored treatment of malignant ascites in patients with advanced epithelial ovarian cancer using aflibercept.54 in this double - blind , placebo - controlled , parallel - group , phase ii study , patients with advanced chemoresistant ovarian cancer and recurrent symptomatic malignant ascites were randomly assigned to receive either intravenous aflibercept ( 4 mg / kg every 2 weeks ) or placebo , stratified according to time interval ( 2 weeks versus > 2 weeks ) between the two most recent paracenteses before randomization.54 the primary efficacy endpoint was time to repeat paracentesis .
a total of 55 patients with a median of four ( range 211 ) previous lines of chemotherapy were randomly assigned to receive placebo ( n = 26 ) or aflibercept ( n = 29 ) . mean time to repeat paracentesis was significantly longer with aflibercept than with placebo ( 55.1 versus 23.3 days ; difference 31.8 days , 95% confidence interval 10.653.1 ; p = 0.0019 ) .
notably , in the aflibercept group , two patients did not need a repeat paracentesis during six months of double - blind treatment . in this subset of heavily pretreated patients with advanced ovarian cancer , three gastrointestinal perforations
were noted in the aflibercept group , and one intestinal fistula was identified in the placebo group .
in addition to the vegf - directed antibodies , bevacizumab and vegf - trap , alternate targeted agents have been investigated in the treatment of ascites .
catumaxomab is a trifunctional monoclonal antibody with two different antigen - binding sites and a functional fc domain.55,56 the two specific antigen - binding sites bind to epithelial tumor cells via the epithelial cell - adhesion molecule ( epcam ) and to t cells via cd3 .
in addition , catumaxomab activates fc receptor i - positive , iia - positive , and iii - positive accessory cells ( dendritic cells , macrophages , and natural cells ) via its functional fc domain ( figure 3).55,56 the functionality and selectivity of this novel antibody rely on the fact that tumor cells in effusions associated with malignant ovarian cancer have been shown to express epcam in 70%100% of cases , while the mesothelial cells lining the peritoneal cavity lack expression.57 following binding with epcam , catumaxomab recruits and activates of immune effector cells , resulting in its antineoplastic activity .
intraperitoneal administration of catumaxomab was first studied in the treatment of eight patients ( two of whom had ovarian cancer ) with malignant ascites in 2005.58 all patients had > 2% epcam expression via flow cytometry on nuclear ascites cells .
seven of eight patients required no further paracentesis during follow - up or until death , with a mean paracentesis - free interval of 38 weeks ( median 21.5 , range 4136 ) . a clinical response with disappearance of ascites
was seen in all patients , and correlated with elimination of tumor cells ( p = 0.0014).58 following this study , a multicenter phase i / ii clinical trial was conducted evaluating the tolerability and efficacy of intraperitoneal catumaxomab in ovarian cancer patients with malignant ascites containing epcam - positive tumor cells.59 twenty - three women with recurrent ascites due to pretreated refractory ovarian cancer were treated with 45 intraperitoneal infusions of catumaxomab at doses of 5200 g over 913 days .
twenty - two of 23 patients did not require paracentesis between the last infusion and the end of the study at day 37.59 the most commonly reported grade 2/3 adverse events in the study were fever , nausea , and vomiting .
recently , a prospective , randomized phase ii / iii study was conducted comparing the efficacy of catumaxomab plus paracentesis with paracentesis alone in the treatment of malignant ascites.57 following paracentesis , catumaxomab was administered at doses of 10 , 20 , 50 , and 150 g on days 0 , 3 , 7 , and 10 , respectively , via an intraperitoneal catheter .
secondary efficacy parameters included time to next paracentesis , signs and symptoms of ascites , and overall survival .
puncture - free survival was significantly longer in the catumaxomab group ( median 46 days ) than in the control group ( median 11 days , hazards ratio 0.254 ; p < 0.0001 ) , as was the median time to next paracentesis ( 77 versus 13 days ; p < 0.0001 , figure 5 ) . within the ovarian cancer cohort ,
median puncture - free survival was 52 days in the catumaxomab arm versus 11 days in the placebo arm ( hazards ratio 0.205 ; p < 0.0001 ) .
in addition , catumaxomab patients had fewer signs and symptoms of ascites than control patients .
the most common adverse events included fever , abdominal pain , nausea , and vomiting ( table 3 ) .
findings from the above trials ultimately resulted in approval by the european medicines agency for catumaxomab for the treatment of malignant ascites in patients with epcam - positive tumors for whom no standard therapy is available.13 given the mouse - rat origin of catumaxomab , limitations in retreatment were anticipated due to formation of human antidrug antibodies . however , in 2011 , pietzner et al described a case of successful retreatment with catumaxomab for the management of malignant ascites.60 a 74-year - old female patient with breast cancer and ascites associated with peritoneal carcinomatosis was treated with catumaxomab , with resolution of her symptoms .
the patient remained puncture - free for 45 days , and evaluation of human antidrug antibody levels demonstrated increased levels after cycle 1 , followed by a considerable decline and a delayed increase in ascites for each subsequent cycle .
this experience suggested that a repeat cycle of catumaxomab might be feasible and effective in patients suffering from recurrent malignant effusions .
in addition to the vegf - directed antibodies , bevacizumab and vegf - trap , alternate targeted agents have been investigated in the treatment of ascites .
catumaxomab is a trifunctional monoclonal antibody with two different antigen - binding sites and a functional fc domain.55,56 the two specific antigen - binding sites bind to epithelial tumor cells via the epithelial cell - adhesion molecule ( epcam ) and to t cells via cd3 .
in addition , catumaxomab activates fc receptor i - positive , iia - positive , and iii - positive accessory cells ( dendritic cells , macrophages , and natural cells ) via its functional fc domain ( figure 3).55,56 the functionality and selectivity of this novel antibody rely on the fact that tumor cells in effusions associated with malignant ovarian cancer have been shown to express epcam in 70%100% of cases , while the mesothelial cells lining the peritoneal cavity lack expression.57 following binding with epcam , catumaxomab recruits and activates of immune effector cells , resulting in its antineoplastic activity .
intraperitoneal administration of catumaxomab was first studied in the treatment of eight patients ( two of whom had ovarian cancer ) with malignant ascites in 2005.58 all patients had > 2% epcam expression via flow cytometry on nuclear ascites cells .
seven of eight patients required no further paracentesis during follow - up or until death , with a mean paracentesis - free interval of 38 weeks ( median 21.5 , range 4136 ) . a clinical response with disappearance of ascites
was seen in all patients , and correlated with elimination of tumor cells ( p = 0.0014).58 following this study , a multicenter phase i / ii clinical trial was conducted evaluating the tolerability and efficacy of intraperitoneal catumaxomab in ovarian cancer patients with malignant ascites containing epcam - positive tumor cells.59 twenty - three women with recurrent ascites due to pretreated refractory ovarian cancer were treated with 45 intraperitoneal infusions of catumaxomab at doses of 5200 g over 913 days .
twenty - two of 23 patients did not require paracentesis between the last infusion and the end of the study at day 37.59 the most commonly reported grade 2/3 adverse events in the study were fever , nausea , and vomiting .
recently , a prospective , randomized phase ii / iii study was conducted comparing the efficacy of catumaxomab plus paracentesis with paracentesis alone in the treatment of malignant ascites.57 following paracentesis , catumaxomab was administered at doses of 10 , 20 , 50 , and 150 g on days 0 , 3 , 7 , and 10 , respectively , via an intraperitoneal catheter .
secondary efficacy parameters included time to next paracentesis , signs and symptoms of ascites , and overall survival .
puncture - free survival was significantly longer in the catumaxomab group ( median 46 days ) than in the control group ( median 11 days , hazards ratio 0.254 ; p < 0.0001 ) , as was the median time to next paracentesis ( 77 versus 13 days ; p < 0.0001 , figure 5 ) . within the ovarian cancer cohort ,
median puncture - free survival was 52 days in the catumaxomab arm versus 11 days in the placebo arm ( hazards ratio 0.205 ; p < 0.0001 ) .
in addition , catumaxomab patients had fewer signs and symptoms of ascites than control patients .
the most common adverse events included fever , abdominal pain , nausea , and vomiting ( table 3 ) .
findings from the above trials ultimately resulted in approval by the european medicines agency for catumaxomab for the treatment of malignant ascites in patients with epcam - positive tumors for whom no standard therapy is available.13 given the mouse - rat origin of catumaxomab , limitations in retreatment were anticipated due to formation of human antidrug antibodies . however , in 2011 , pietzner et al described a case of successful retreatment with catumaxomab for the management of malignant ascites.60 a 74-year - old female patient with breast cancer and ascites associated with peritoneal carcinomatosis was treated with catumaxomab , with resolution of her symptoms .
the patient remained puncture - free for 45 days , and evaluation of human antidrug antibody levels demonstrated increased levels after cycle 1 , followed by a considerable decline and a delayed increase in ascites for each subsequent cycle .
this experience suggested that a repeat cycle of catumaxomab might be feasible and effective in patients suffering from recurrent malignant effusions .
malignant abdominal effusions affect a significant proportion of patients suffering from advanced ovarian cancer , and are associated with troubling symptoms including abdominal pain , dyspnea , bloating , weight loss , and bowel and bladder dysfunction .
the biology of the disease and its propensity for peritoneal spread are unique , predisposing patients to formation of ascites .
to date , no consensus has been reached regarding the treatment of ascites in patients with ovarian cancer .
traditional treatment methods , including salt restriction , diuretics , sclerosing agents , radioactive isotopes , paracentesis , and shunt placement , have shown limited and variable efficacy with significant toxicities . more recently , targeted therapies have emerged as promising alternatives for the management of malignant effusions .
our understanding of the contribution of angiogenesis to ascites formation has resulted in the study of the antiangiogenic antibodies , bevacizumab and vegf - trap , which have shown clinical efficacy in cohorts of heavily pretreated patients .
in addition , the trifunctional antibody , catumaxomab , has shown positive signals in the treatment of malignant ascites .
ultimately , as with all novel therapies , symptom relief and treatment goals must be weighed against patient discomfort and potentially lethal adverse events .
careful patient selection and identification of risk factors to help reduce significant side effects associated with treatment are required .
further comparative studies and quality of life assessments are warranted before incorporation of these agents into daily practice .
Output:
| malignant ascites affects approximately 10% of patients with recurrent epithelial ovarian cancer and is associated with troublesome symptoms , including abdominal pressure and distension , dyspnea , bloating , pelvic pain , and bowel / bladder dysfunction . to date , no effective therapy has been identified for the treatment of malignant ascites in patients with recurrent , advanced ovarian cancer . in this article , we discuss currently existing options for the treatment of ascites associated with ovarian cancer , and review the literature as it pertains to novel , targeted therapies .
specifically , preclinical and clinical trials exploring the use of the antiangiogenic agents , bevacizumab and vascular endothelial growth factor - trap , as well as the nonangiogenic agent , catumaxomab , will be reviewed . despite current limitations in treatment ,
knowledge regarding management options in the palliation of ascites is critical to practicing physicians .
ultimately , as with all novel therapies , symptom relief and treatment goals must be weighed against patient discomfort and potentially significant adverse events . |
PubmedSumm118650 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: internal jugular vein ( ijv ) catheterization is commonly used to obtain temporary access to circulation enabling hemodialysis .
however , significant complications such as internal carotid artery ( ica ) puncture , pneumothorax , vessel erosion , thrombosis , airway obstruction , and infection can occur .
this , along with their comorbid conditions , increases the risk of such complications . here , we report a patient on hemodialysis who developed right subclavian artery pseudoaneurysm following the right ijv catheterization .
we are describing a case of brachial plexus compression attributable to delayed recognition of a right subclavian artery pseudoaneurysm as a complication of jugular venous catheterization of hemodialysis catheter .
any neck swelling , new bruit , and the symptoms of brachial plexopathy after jugular venous catheterization warrant an intensive investigation to exclude arterial injury .
a 20-year - old boy with end - stage renal disease was admitted to a hospital with metabolic acidosis and uremia .
an 18 gauge needle was inserted percutaneously by landmark method via central approach which resulted in arterial puncture ; needle was removed , and firm pressure was applied for 5 min .
the second attempt via low central approach was done so as to avoid carotid artery puncture which was successful and a double lumen hemodialysis catheter was inserted with seldinger technique via right ijv , and the patient underwent heparin free hemodialysis .
the patient complained of pain and swelling in the right supraclavicular region after 4 days of insertion of the catheter and then the swelling increased in size along with weakness in his right upper limb .
color doppler study of neck vessels showed a partially thrombosed pseudoaneurysm formation of size 5.6 cm 4.2 cm seen in the right supraclavicular region , showing underlying aneurysm measuring 1.9 cm 1.3 cm within the lesion which showed turbulent flow with whirling in the pseudoaneurysm and appeared to be communicating with right subclavian artery with normal color flow in carotid artery and ijv .
the patient was subjected to computed tomography angiography to determine origin of pseudoaneurysm which revealed 5.5 cm 7.5 cm 8.5 cm hematoma in right subclavian fossa with blood fluid levels [ figures 1 and 2 ] .
there was extravasation of contrast into hematoma likely from thyrocervical trunk approximately 7.5 mm away from its origin from subclavian artery .
over next 24 h , the patient was unable to move his right upper limb with increasing pain , so he was subjected to open surgical pseudoaneurysmectomy .
computed tomography angiography of neck vessels computed tomography angiography of neck vessels showing pseudoaneurysm on the right side
right ijv catheterization is commonly used perioperatively for invasive monitoring as well as administration of fluid and vasoactive drugs and emergent hemodialysis .
the advantages are straight course into superior vena cava , superficial location , and definite landmarks for placement .
arterial injury leading to hematoma formation , arterial dissection , arteriovenous fistula , or pseudoaneurysm is known as catheter - related cervicothoracic arterial injuries .
mallory et al . published a prospective , randomized study indicating a higher rate of success and a lower number of attempts and immediate complications for ijv catheterization with bi - dimensional ultrasound versus the anatomical landmarks technique dolu et al . also found that ijv catheterization guided by real - time ultrasonography ( usg ) resulted in a lower access time and lower rate of attempts .
pseudoaneurysm results from a variety of causes such as infection , trauma , and surgical procedures .
the most common mechanism is disruption of arterial continuity with extravasation of blood into surrounding tissue .
this results in the formation of fibrous tissue capsule which progressively enlarges because of underlying arterial pressure . in the present case
, the accidental penetration injury of the right subclavian artery associated with low puncture might have led to pseudoaneurysm formation which progressively expanded due to arterial pressure .
hematoma usually appears shortly after the procedure and tend to resolve in time depending on size , location , and extent of injury whereas pseudoaneurysm may appear later with pulsatile and expanding mass .
duplex usg will help to differentiate between two , and a selective angiogram is necessary to determine precise origin and extent of injury . in our case , initially , we attributed brachial plexus compression due to hematoma in neck .
because of close anatomic relationship between brachial plexus and subclavian artery in the thoracic inlet , even a small false aneurysm can result in compression injury to the neuroplexus . because brachial palsy has a poor prognosis
when recognition is delayed , an aggressive approach is advocated . in our review , early surgical intervention of compressive hematoma within 48 h resulted in improvement in all patients while late intervention after 48 h resulted in improvement in about half of patients .
treatment options for pseudoaneurysm are usg - guided compression , percutaneous thrombin injection , coil embolization , endovascular stents , and open surgical repair .
usg - guided compression which is frequently used for ablation of femoral pseudoaneurysm was not possible in our case because of depth of the artery and overlying bone .
cardiothoracic and vascular surgeon was consulted for endovascular stenting but was not feasible due to risk for cerebral embolization and stroke .
few studies showed that early intervention within 48 h resulted in improvement in all patients while late intervention resulted in improvement in about half of patients .
for all traumatic injuries of attempted jugular venous catheterization , particularly arterial puncture , an aggressive investigational approach is recommended .
any neck swelling or symptoms of brachial plexopathy should arise the suspicion of pseudoaneurysm and confirm by color doppler study . a symptomatic pseudoaneurysm should be treated without delay to prevent permanent neurological damage .
Output:
| internal jugular vein ( ijv ) catheterization has become the preferred approach for temporary vascular access for hemodialysis .
however , complications such as internal carotid artery puncture , vessel erosion , thrombosis , and infection may occur .
we report a case of brachial plexus palsy due to compression by right subclavian artery pseudoaneurysm as a result of ijv catheterization in a patient who was under maintenance hemodialysis . |
PubmedSumm118651 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: testing of blood - fed mosquitoes plays an integral role in the surveillance for arboviruses to understand the interaction mechanisms between host , vector and reservoir , and to identify and evaluate the role of potential bridge vector species in transmission of pathogens of public health importance .
additionally , blood - fed mosquitoes can give us information regarding the feeding preference , seroconversion status of that host , infectivity level of the reservoir host , etc .
, which immensely helps researchers in understanding the ecology of arboviruses . sampling a blood - fed mosquito is equivalent to sampling a host - seeking mosquito as well as a wild bird simultaneously . for the purpose of arbovirus surveillance
different types of traps are available in the market for trapping mosquitoes which can be basically grouped into three main categories .
evs traps collect host - seeking mosquitoes but as they have not yet taken blood - meal the majority of them are sterile / non - infective and non - blood - feds .
gravid traps are attractant towards oviposition females after they have digested the blood - meal and are ready to lay eggs .
resting boxes are attractant to mosquitoes after they have taken blood - meal and should be ideal for collection of blood - fed mosquitoes .
surprisingly , review of the literature revealed that on the us east coast , resting boxes were the least successful for disease surveillance purposes because of their low mosquito trap count .
the present study was conducted to evaluate the efficacy of resting boxes in comparison with gravid traps for collecting blood - fed female mosquitoes of different species in the northwestern part of the riverside county of california .
three trapping sites were selected in the northwest mosquito and vector control district ( nwmvcd ) of the riverside county of california based upon their resemblance to semi - urban and rural topographies [ figure 1 ] .
these sites had a mixed resident population of horses , dogs , birds and humans .
one resting box measuring h d w : 6 6 4 [ figure 2 ] was placed at each selected site , in shade under a tree , with its open end facing south .
resting mosquitoes were aspirated once a week with in - house - developed battery - operated mechanical aspirator [ figure 3 ] .
overnight trappings were done on a weekly basis between july - december 2009 . to maintain consistency trap deployment and mosquito collection
mosquitoes were collected the next morning at the same time during cooler hours ( before 9 am ) ; transported to the nwmvcd laboratory over blue ice ; identified up to species level on chill table ; and classified as male , female and blood - fed females .
the data was stored in microsoft excel spread data sheet and statistically analyzed for percentage proportion of species , sex and blood - fed females of each species collected per trap type .
the brief description about the three study sites is as under : resting box used in the present study in - house - developed battery - operated mechanical mosquito aspirator located in the city of norco ( latitude : 335623.7n , longitude : 1173259.4w , altitude : 504 feet , semi - urban type ) , this site provides indoor and outdoor boarding facility to 55 horses .
in addition to horses , there were over 300 chicken roosters ( gallus gallus ) , 10 goats ( capra hircus ) , 4 watchdogs ( corgi mixed breed ) and 8 human attendants living on the property .
three sides of this ranch have boundaries with neighboring horse - boarding facilities . located in the city of norco ( latitude : 335411.05n , longitude : 1773312.76w , altitude : 533 feet , semi - urban type ) , this is a horse boarding place with indoor and outdoor riding arenas .
thirty - five horses were living in this place with four dogs ( labrador mix breed ) and four humans .
the east side of this property has an approach road while the west side of the property has a huge pond filled with waste runaway rainwater .
located in the city of mira loma ( latitude : 335826.28n , longitude : 1772959.04w , altitude : 559 feet , rural type ) , this site has outdoor horse boarding with 40 horses in addition to 5 dogs ( 3 : pomerians , 2 : labrador mix breed ) .
this site mimics a rural setup with the south end touching the basin of santa ana river and having floodwater wash on the east side .
located in the city of norco ( latitude : 335623.7n , longitude : 1173259.4w , altitude : 504 feet , semi - urban type ) , this site provides indoor and outdoor boarding facility to 55 horses .
in addition to horses , there were over 300 chicken roosters ( gallus gallus ) , 10 goats ( capra hircus ) , 4 watchdogs ( corgi mixed breed ) and 8 human attendants living on the property .
located in the city of norco ( latitude : 335411.05n , longitude : 1773312.76w , altitude : 533 feet , semi - urban type ) , this is a horse boarding place with indoor and outdoor riding arenas .
thirty - five horses were living in this place with four dogs ( labrador mix breed ) and four humans .
the east side of this property has an approach road while the west side of the property has a huge pond filled with waste runaway rainwater .
located in the city of mira loma ( latitude : 335826.28n , longitude : 1772959.04w , altitude : 559 feet , rural type ) , this site has outdoor horse boarding with 40 horses in addition to 5 dogs ( 3 : pomerians , 2 : labrador mix breed ) .
this site mimics a rural setup with the south end touching the basin of santa ana river and having floodwater wash on the east side .
during this study period ( july to december 2009 ) , 3953 mosquitoes ( 826 blood - fed females ) belonging to three different genera and eight species were collected in various traps . resting boxes ( rb ) collected maximum variety of different mosquito species ( rb : seven , gravid : one , evs : three species ) .
quinquefasciatus ( rb : 70.7% and gravid : 97.4% of their total respective mosquito collection ) .
quinquefasciatus is one of the local competent vectors for west nile virus ( wnv ) and other arboviruses . during this study period , out of the total 2474 mosquitoes collected from resting boxes
, the majority ( 98.3% ) of the females belonged to the culex genus comprising five species ( cx .
the proportion of blood - fed females of the culex species collected in resting boxes was 28.8 times more , while of blood - fed females of cx .
overall , the proportion ( 63.3% of the total 1273 female mosquitoes collected ) of blood - fed female mosquitoes collected was the highest in resting boxes followed by gravid traps with 2.2% of their individual total female count .
species - wise , 63.4% of culex , 50% of culiseta and 61.35% of anopheles females collected in resting boxes were blood - fed while the proportion of blood - fed females of these three genera in gravid traps was very low [ table 1 ] .
historically speaking , since the invasion of southern california by wnv in 2003 , it has been detected in pools of cx .
resting boxes collected blood - fed female mosquitoes of all the above species except cx .
erythrothorax which are commonly found in the wetland area containing cattails ( typha spp . ) and bullrush ( schoenoplectus californicus ) .
although in the present study area all the three collection sites were lacking such ecotone , some host - seeking but non - blood - fed cx .
the success of resting boxes in collecting such a huge proportion of blood - fed females was due to their strategic locations i.e. they were strategically placed close to a potential source of blood - meals .
after taking blood - meal , it is insect physiology that female mosquitoes try to rest at the next available cool dark place for its digestion and production of eggs .
a resting box nearby offered such cool dark shade and care was taken to avoid exposure of resting mosquitoes to sunlight from the setting or rising sun by facing the open face of the box towards the south .
another important aspect for a higher proportion of blood - fed mosquitoes from resting boxes was the aspiration time .
resting boxes were aspirated during early morning cooler hours ( not later than 9 am in the present study area ) as with the rising sun , the temperature also rises , resulting in flying away of blood - fed females . during this study ,
whenever we were in the neighborhood of resting boxes , they were checked for the presence of mosquitoes during mid - day or afternoon hours . since resting boxes
do not have any trap - door or fan to hold back the mosquitoes , they were either found empty or having very few mosquitoes .
so if a researcher did not come to collect the mosquitoes from resting boxes during morning cooler hours , he / she would be disappointed with their collection ability .
thus , resting boxes proved to be a huge success in collection of blood - fed mosquitoes in the northwestern part of riverside county .
during this study period mosquitoes belonging to three different genera and eight species were collected in various traps .
quinquefasciatus , which is one of the local competent vectors for wnv and other arboviruses .
the proportion of blood - fed females of the culex species collected in resting boxes was 28.8 times more , while of blood - fed females of cx .
additionally , in comparison to gravid traps , resting boxes require no batteries or dry ice to operate , generate no hazardous waste , require less man - hours per mosquito collection , have extremely low running cost and are not prone to thefts or vandalisms .
these advantages make the choice of resting boxes extremely beneficial to researchers and public health agencies who have limited resources , especially in developing / underdeveloped countries where the epidemics of arboviruses , e.g. dengue , chickungunya , etc .
Output:
| objectives : testing of blood - fed mosquitoes plays an integral role in arbovirus surveillance and in understanding its interaction mechanisms between host , vector and reservoir .
the present study was undertaken to evaluate the efficacy of two different traps ( gravid and resting boxes ) for collection of blood - fed mosquitoes in the northwestern part of riverside county.materials and methods : three trapping sites were selected in the northwest mosquito and vector control district of riverside county , california . at each site resting boxes and gravid traps were set ; and mosquitoes were collected on a weekly basis between july - december 2009 .
mosquitoes were transported over blue ice , identified up to species level on chill table , and classified as male , female and blood - fed females.results:during this study period , 3953 mosquitoes ( 826 blood - fed females ) belonging to three different genera and eight species were collected ; resting boxes collecting maximum number ( seven ) of mosquito species .
overall as well as individually in each trap kind , the most abundant mosquito species collected was cx .
quinquefasciatus .
the proportion of blood - fed females of the culex species collected in resting boxes was 28.8 times more , while of blood - fed females of cx .
quinquefasciatus was 32.2 times more than the proportion collected from gravid traps.conclusions:overall , the proportion of blood - fed female mosquitoes collected for each species trapped was highest in resting boxes .
additionally , resting boxes showed the advantage of extremely low running and maintenance cost ; generation of no hazardous waste ; quick turnaround time in terms of mosquito collection per man - hour spent ; and they were less prone to vandalism or thefts . |
PubmedSumm118652 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: the white mycelia were readily visible nearby soil surface fruit and grew inside of fruit tissues .
the fungus produced numerous small globoid sclerotia of uniform size which were initially white but turned brown .
in gyeongsangnam - do , the melon is cultivated as a cash crop and its cultivation increases annually .
abundant sclerotia were often produced on the surfaces of infected fruits and near the soilline in vinyl houses , which play an important role of secondary inoculum as soil born diseases in the fields .
infected fruits were collected from the fields and isolated to globoid dark brown sclerotia on surface fruit .
the sclerotia were disinfected in a 1% naocl solution for 60 seconds then washed in distilled water 3 times .
after incubated for 4 days at 25 , the mycelial tips were cut and transferred to fresh pda for further study .
the growth pattern of the fungus was examined after incubation for 20 days at 25 to 30. the fungus grew between 10 and 35 and optimal temperature for the growth was 30 on pda .
the white mycelium usually formed many narrow hyphal strands in the aerial mycelium which were 3 to 8 m in width .
small , uniformly sized , globoid sclerotia were produced in great numbers.the sclerotia were initially white then turned to dark brown at maturation .
the maximum numbers of sclerotia were produced at 25 to 30. the size of sclerotia were 1 to 3 mm ( fig .
the pathogenicity of the fungus on melon ( cucumis melo ) was tested in a greenhouse at gyeongsangnamdo agricultural research and extension services in may 2008 .
the fruits were inoculated with 100 g of the inoculum source near the basal end of fruit .
the pathogen was reisolated from the lesions to prove koch 's postulate . on the basis of symptoms , mycological characteristics and pathogenicity to the host plant ,
Output:
| in 2007 to 2008 , a fruit rot of melon ( cucumis melo l. ) caused by sclerotium rolfsii occurred sporadically in a farmer 's vinyl house in jinju city .
the symptoms started with watersoaking lesion and progressed into the rotting of the surface of fruit .
white mycelial mats appeared on the lesion at the surface of the fruit and a number of sclerotia formed on the fruit near the soil line .
the sclerotia were globoid in shape , 1~3 mm in size , and white to brown in color .
the hyphal width was measured 3 to 8 m .
the optimum temperature for mycelial growth and sclerotia formation was 30 on pda .
typical clamp connections were observed in hyphae of grown for 4 days on pda . on the basis of symptoms , mycological characteristics and pathogenicity to the host plant ,
this fungus was identified as sclerotium rolfsii saccardo .
this is the first report of the fruit rot of melon caused by s. rolfsii in korea . |
PubmedSumm118653 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: use of dental implants has become a widespread and predictable treatment modality for the restoration of missing teeth and various edentulous cases . as progress in material and
implant design continues dramatically over time , implant patients have been demanding treatment protocols that take less time and require fewer surgeries . consequently , immediate loading of dental implants has gained popularity and becomes more and more required . a fundamental prerequisite for immediate
primary stability is defined as the absence of mobility in the bone bed after the implant has been placed .
it depends on mechanical engagement of an implant with the fresh bone socket , but this stability declines with time during the early stages of healing , as remodeling of the surrounding bone takes place .
while secondary stability is the progressive increase in stability related to biologic events at the bone - implant interface such as new bone formation and remodeling , it is absent at the time of implant placement and increases with time .
in addition to considering the primary implant stability a critical factor when immediate loading is planned , it is one of the prerequisites for achievement and maintenance of osseointegration . besides the quantity and quality of the bone [ 4 , 7 ] , morphology of the implant , implant surface roughness , and topography [ 8 , 9 ] ,
the surgical technique adopted also influences the primary stability [ 4 , 10 ] . likewise
one of the surgical techniques suggested to enhance the primary stability of implant in bone of low density is the undersized drilling technique , which has been introduced to locally optimize the bone density by using a final drill diameter considerably smaller compared with the implant diameter . in this way ,
an osteocompressive fit between the implant surface and bone bed is achieved . however , a drawback of all drilling techniques is that bone tissue is sacrificed during the drilling process .
this shortcoming is exacerbated in situations where limited bone or bone of lesser density is available . in view of this , the osteotome technique has been introduced .
this technique consists of first preparing a small - sized pilot hole , then compressing the bone tissue laterally and apically with a spreader or implant - shaped instrument .
the goal of this technique is to replace the implant with a high degree of stability without removing additional bone , which is theoretically believed to improve final bone healing [ 1517 ] .
in addition to conventional surgical preparation techniques , the piezoelectric bone surgery [ 18 , 19 ] offers an alternative technique to implant placement that professes to address some of the shortcomings of the conventional system utilizing an ultrasonic surgical system .
the piezoelectric surgery unit claims to be superior to conventional methods in numerous ways : improved precision , selective cutting action , minimal damage to soft tissues such as nerves or blood vessels , reduced bleeding resulting in improved visibility within the surgical field , and the absence of overheating [ 19 , 20 ] .
currently , the effect of ultrasounds is being widely investigated in various fields of medicine : in orthopedics , they are used to accelerate healing of bone fractures and ligament damage by promoting cell proliferation and bone matrix synthesis [ 2123 ] .
also , multidisciplinary clinical reports on the application of ultrasounds in bone surgery obtained promising results in terms of precision and safety [ 24 , 25 ] .
the use of low - level lasers has also been suggested as another way of accelerating and improving the bone tissue healing process .
laser light irradiation has been applied in the medical field and has biostimulatory effects on wound healing , collagen synthesis , and fibroblast proliferation [ 2729 ] .
in addition , it has been demonstrated that bone irradiated mostly with infrared wavelengths shows increased osteoblastic proliferation , collagen deposition , and bone formation when compared to nonirradiated bone [ 30 , 31 ] . however , little reliable data exist concerning the laser effect on the osseointegration process of implants . therefore ,
this review aimed to find if there is scientific - based evidence to support laser influence on stability of dental implants . nowadays , various computer - assisted systems comprising a three - dimensional virtual planning by means of a computer tomography ( ct ) or digital volume tomogram suggest a flapless procedure . for the accurate and predictable placement of the implants ,
a surgical template is fabricated based on the virtual planning and consequently a prosthetically driven and template - guided implant placement can be carried out . according to oh et al .
, a flapless implant surgery provides esthetic soft tissue results in single - tooth implants either immediately or delayed loaded .
it has been documented that the use of stereolithographic appliances in accordance with flapless surgery assists in the immediate loading of implants .
also , immediate loading with flapless surgery technique has been shown to reduce the treatment period and enhance implant stability compared to the conventional flap surgery protocol [ 36 , 37 ] .
different clinical methods for monitoring implant stability at various stages have been proposed , such as periotest ( siemens ag , bensheim , germany ) , dental fine tester ( kyocera , kyoto , japan ) , osstell mentor ( osstell ab , stampgatan , gteborg , sweden ) , and the cutting - torque or insertion torque ( it ) measurement .
the periotest is composed of a metallic tapping rod in a handpiece , which is electromagnetically driven and electronically controlled .
signals produced by tapping are converted to unique values called periotest values ( ptv ) .
however , periotest and dental fine tester have been the subject of criticism as a result of their poor sensitivity and because their measurements are significantly influenced by variables such as the vertical measuring point on the implant abutment , the handpiece angulations , and the horizontal distance of the handpiece from the implant [ 39 , 40 ] . the osstell resonance frequency analysis ( rfa ) system involves the placement of a smart peg into the implant , which is screwed into the implant itself and the use of a transducer , which is held close to and perpendicular to the smart peg without actually making contact .
osstell gives the implant stability quotient ( isq ) through resonance frequency analysis on a scale from 1 to 100 .
recent studies have shown the isq to be an accurate , noninvasive means of determining implant stability , and it is becoming a widely used instrument [ 4244 ] to monitor the changes in stiffness and stability at the implant - tissue interface and to discriminate between successful implants and clinical failures [ 44 , 45 ] . regarding the cutting - torque or insertion torque measurement which was originally developed by johansson and strid and later improved by friberg et al . , its main purpose was to quantify the initial torque ( in ncm units ) required to seat the implant into the socket during surgery by means of a torque application device ( osseocaret ) and thereby predict bone support and density .
although this method is nonsubjective , noninvasive , and extensively used in clinical practice during implant placement to assess primary stability , it allows only a single measurement at implant insertion and can not be used for evaluating secondary stability . considering that the surgical technique might influence the primary and secondary stability of dental implants , the aim of this systematic review was to investigate the influence of different surgical techniques including the undersized drilling , the osteotome , the piezosurgery , the flapless procedure , and the bone stimulation by low - level laser therapy on the primary and/or secondary stability of dental implants .
the present systematic review was focused on this question : is there scientific evidence to support the influence of these surgical techniques on the primary and/or secondary stability of dental implants ?
the inclusion criteria comprised observational clinical studies and randomized controlled trials ( rcts ) conducted in patients who received dental implants for rehabilitation , studies that evaluated the association between the surgical technique ( prognostic factor ) and implant primary and/or secondary stability ( outcome ) .
surgical techniques evaluated were the underdrilling technique , osteotome technique , piezosurgery , flapless technique , and the low - level laser therapy .
dental implant stability was evaluated by isq value ( osstell , integration diagnostics , gothenburg , sweden ) , ptv value ( periotest , medizintechnik gulden , modautal , germany ) , or it measurement .
studies that reported surgical technique and implant stability but did not verify their association were excluded from this systematic review . for the identification of the clinical studies to be considered in this review ,
combinations of the following keywords were used : dental implants , implant stability , primary stability , secondary stability , implant stability quotient , isq , resonance frequency analysis , rfa , osstell , periotest value , ptv , periotest , osteotome technique , undersized drilling , piezosurgery , surgical technique , flap implant placement , and flapless implant placement .
a search of health science databases ( cochrane library and medline - pubmed ) and grey literature was performed , including papers published until may 2013 .
. only articles in english were included in this review . the titles and abstracts ( when available ) of all articles identified through the electronic searches were scanned independently by at least two review authors . for studies appearing to meet the inclusion criteria , or for which there were insufficient data in the title and abstract to make a clear decision ,
the full reports were assessed independently by at least two review authors to establish whether they met the inclusion criteria or not .
studies rejected at this or subsequent stages were recorded in the flow diagram of literature review , and reasons for exclusion were recorded .
data were extracted by at least two review authors independently using specially designed data extraction form . any disagreement was discussed and a third review author was consulted where necessary ( figure 1 ) . for each study , the following data were extracted ( table 1).year of publishing , country of conducting the study , sample size , and number of implants.implant dimensions , surface treatment , and implant manufacturer.arch region of implant insertion and the surgical technique used.primary stability isq or it values and association between primary stability and surgical technique.confounders included in analysis.secondary stability isq or it values and association between secondary stability and surgical technique .
year of publishing , country of conducting the study , sample size , and number of implants .
the risk of bias assessment for the included studies was considered independently and in duplicate by at least two review authors .
this was conducted using the methodological checklist for prognostic studies developed by the national institute for health and clinical excellence of the united kingdom ( 2009 ) ( table 2 ) .
response always indicates that the study has been designed and conducted in such a way as to minimize the risk of bias for that item .
an unclear response to a question may arise when the answer to an item is not reported or is not reported clearly .
a study was classified as having high methodological quality if at least five of six parameters received the answer
yes , moderate methodological quality if at least three of the parameters received the answer
yes , or low methodological quality if two or less parameters received the answer
the search procedure retrieved 59 articles from electronic searches . after screening the titles and abstracts ( when available ) independently by at least two review authors , 14 articles appeared to meet the inclusion criteria [ 11 , 32 , 37 , 4853 , 5559 ] .
of the 14 potentially eligible studies , 5 studies had to be excluded because relation between surgical technique and implant stability was not clear in one study , in two studies intervention was confounded [ 37 , 56 ] , one study did not include a control group , and one study did not study the surgical technique influence on implant stability .
thus , a total of 9 clinical studies [ 11 , 32 , 4853 , 55 ] that met the inclusion criteria underwent quality assessment and data extraction .
( 1 ) undersized implant site preparation . will undersized implant site preparation affect primary and/or secondary stability ?
two observational clinical studies [ 51 , 52 ] studied this intervention . a clinical study compared between the undersized implant site preparation and conventional implant site preparation with respect to the primary stability .
the implants were inserted in posterior maxilla ; six groups with 10 implants each , two controls ( c1 and c2 ) , and four tests ( t1t4 ) were created according to the implant dimensions and the surgical technique adopted . in c1 group , implants of 3.75 mm width and 10 mm length were used with the 2- and 3-mm diameter drills reached up to 10 mm length . in t1 group , implants of 4 mm width and 10 mm length were used , with the 2- and 3-mm diameter drills reached up to 10 mm length . in t2
group , implants of 4 mm width and 10 mm length were used , with the 2-mm dill reached to 10 mm , and the 3-mm drill reached to 7 mm length . in c2 group ,
implants of 3.75 mm width and 11.5 mm length were used with the 2- and 3-mm diameter drills reached up to 11.5 mm length . in t3 group ,
implants of 4 mm width and 11.5 mm length were used with the 2- and 3-mm diameter drills reached up to 11.5 mm length .
finally , in t4 group , implants of 4 mm width and 11.5 mm length were used with the 2-mm drill reached up to 11.5 mm and the 3-mm diameter drills reached up to 8.5 mm length .
both isq and it values were recorded at implant placement to evaluate the primary stability .
the other clinical study investigated the effect of undersized drilling technique on primary implant stability when compared with the standard drilling protocol .
undersized bone drilling was performed using 2.8 mm twist drills for 4.1 mm diameter implants ; widening of implant bed with osteotome or tapping was not used .
implants with same dimensions ( 12 4.11 mm ) were used in both groups .
isq and it values were recorded at implant placement to evaluate the primary stability .
( 2 ) osteotome technique . will osteotome technique affect primary and/or secondary implant stability ?
one rct and two clinical observational studies [ 48 , 50 ] studied this intervention . a clinical observational study compared conventional implant placement with osteotome technique to place 10 implants in maxillary anterior region .
the implants were placed in the first quadrant using the conventional method ( group a ) and in the second quadrant using the osteotome technique ( group b ) . for group a the implant sites
were sequentially enlarged to 3.7 mm in diameter with pilot and spiral drills according to standard protocol , in group b the implant sites were prepared initially by a 2 mm diameter pilot drill , this was followed by condensing the bone using osteotomes of increasing diameters using a hand ratchet . once the implant sites were prepared , implants of 13 mm length and 3.7 mm width were inserted .
isq values of implant stability were measured at implant placement and at six months after .
a total of 102 implants were placed in posterior segment of maxilla , 51 self - tapping ( 4 mm in width and 10 mm in length ) implants , and 51 non - self - tapping ( 4.1 mm in width and 10 mm in length ) .
four study groups were formed according to the surgical technique to be used for implant site preparation and implant macrodesign . in group i : bone condensation technique was used for implant site preparation and self - tapping implants were inserted ; group ii : non - self - tapping implants were placed following condensation technique ; group iii : self - tapping implants were inserted after bone drilling ; and in group iv : bone drilling was performed and non - self - tapping implants were placed . in groups
i and ii , bone condensation technique was performed by pilot drill and bone condensers of increasing diameter , while in groups iii and iv , implant sites were gradually enlarged with pilot and spiral drills .
one rct compared the conventional drilling technique and the osteotome technique in anterior segment of the maxilla .
46 screw type oral implants with the length of 10 or 12 mm and diameter of 4.1 mm were used . for control group ,
implant bed sites were prepared with pilot and spiral drills to a final diameter of 3.3 mm according to protocol recommended by manufacturer .
for the test group after preparing a pilot hole with 2.2 mm diameter drill , the procedure was continued with series of consecutive osteotomes to a final diameter of 3.5 mm according to manufacturer instructions .
all implants were placed in the sites using a nonsubmerged technique and in one stage procedure .
isq values representing implant stability were measured at implant placement and at three months after .
one rct compared piezosurgery with conventional implant bed preparation . the trial was conducted using split mouth technique in 20 patients .
the control site was performed with conventional twist drills and the test site was performed with specific piezoelectric inserts .
the last instrument used was 3 mm in diameter in both groups to place 4 mm diameter and 10 mm length implants .
one observational clinical study compared placement of implants with flap elevation versus flapless implant placement with respect to primary and secondary implant stability .
forty patients with complete edentulous maxilla were consecutively admitted for treatment with implant supported prosthesis .
one hundred and ten implants were placed conventionally in 23 patients ( flap group ) and eighty five implants in 17 patients by means of flapless method ( flapless group ) using a stereolithographic template .
the isq values were recorded immediately after implant placement and after a period of 3 months .
one rct compared implant placement with low - level laser irradiation with implant conventional placement without laser irradiation .
thirty implants were distributed bilaterally in posterior mandible of eight patients . at the experimental side
the implants were submitted to low - level laser treatment and in the control side the irradiation was simulated ( placebo ) .
the irradiations were performed with a gallium aluminum - arsenide ( gaalas ) diode low - level laser with continuous emission of 830 nm wavelength .
the first irradiation was performed in the immediate post - operation period and was repeated every 48 hours in the first 14 days .
none of the articles was excluded from the systematic review after quality assessment , except for one article on studies [ 50 , 55 ] conducted by the same author and having some overlapping patients . in this case , after ranking the studies , the one with the highest score was included in the systematic review , the other was excluded . a priori calculation for the sample size
inclusion and exclusion criteria for the sample selection were clearly defined in only five studies [ 11 , 32 , 49 , 50 , 53 ] . in addition , blinding of outcome assessors were mentioned by the authors in only three of the included studies [ 11 , 50 , 53 ] .
finally , confounders were not considered for analysis in three studies [ 32 , 49 , 52 ] .
consequently , the quality assessment and control of bias ranked five articles as moderate and three as high ( table 3 ) .
( 1 ) will undersized implant site preparation affect primary and/or secondary stability ? in both studies [ 51 , 52 ] , the difference in isq and it values among the undersized drilling and the standard press - fit drilling techniques was not statistically significant ( p > 0.05 ) , but it was clearly in favour of the undersized group . however , secondary stability was not evaluated .
they demonstrated a statistically significant higher primary stability for implants placed with osteotome technique than those placed with the conventional drilling technique in the maxillary anterior and maxillary posterior regions , based on isq values ( p < 0.05 ) .
in contrast , padmanabhan and gupta , based on isq values , demonstrated a statistically significant higher primary stability for implants placed with conventional drilling technique than those placed with osteotome in the maxillary anterior region ( p < 0.05 ) .
with respect to the influence of osteotome technique on secondary implant stability , there was no significant influence of using osteotome on secondary implant stability when compared with conventional drilling technique for isq values , in the two selected studies [ 48 , 49 ] ( p > 0.05 ) .
on the other hand , markovi et al . showed a statistically significant higher secondary stability for implants placed with osteotome technique than those placed with the conventional drilling technique during the entire 12-week observation period , based on isq values ( p < 0.05 ) .
the single rct demonstrated that there was no real difference in primary stability when implants were placed following piezoeletric technique versus the conventional twist - drill technique ( p > 0.05 ) .
however , it found a statistically significant higher secondary stability for piezogroup than the control group .
this statistically significant difference was during the entire follow - up 90 days , and from day 14 to day 42 , in particular , the difference was extremely significant ( p < 0.0001 ) .
the one observational clinical study demonstrated that there was a positive association between the flapless technique and the primary and secondary implant stability at three months after surgery ( p < 0.001 ) .
( 5 ) will low - level laser therapy affect primary and/or secondary stability of implants ? the one rct concluded that there was no evidence of any effect of irradiating bone osteotomies with infrared wavelengths on either primary or secondary implant stability within 12-week follow - up in the posterior mandible , when measured by rfa .
the purpose of this systematic review was to evaluate whether there was scientific evidence to support the association between different surgical techniques and primary and/or secondary implant stability .
the surgical techniques that we found in the world literature evaluated by clinical studies whether they have influence on primary and/or secondary implant stability were the undersized drilling , the osteotome technique , the piezosurgery , the flapless , and the low - level laser therapy .
just three randomized controlled trials ( rcts ) and five observational clinical studies were included .
we selected only clinical studies that verified the association between the surgical techniques and implant stability .
laboratory or animal studies which did not report any clinical implant - related outcomes were not considered of interest since they would not be able to provide reliable clinical information for the prognosis of dental implant rehabilitation . because only a limited number of studies investigated the influence of different surgical techniques on stability of dental implants ,
the pattern of the current literature review was customized to primarily summarize the pertinent information . when evaluating whether the undersized drilling technique could enhance the primary implant stability , the two included observational clinical studies [ 51 , 52 ] did not show a significant difference between the undersized drilling and the standard press - fit drilling techniques , but it was clearly in favour of the undersized group .
the authors concluded that using thinner drills for implant placement in sites with poor bone density ( posterior edentulous maxilla and mandible ) is beneficial in enhancing primary implant stability .
the higher primary stability of implants inserted after undersized drilling compared with those inserted after standard press - fit drilling might be interpreted by that the implants placed in undersized beds could compress the bone and increase its density , thereby enhancing the primary implant stability .
however , why no significant difference was detected between the under drilling and the press - fit techniques could be interpreted by the relatively small sample size of those two studies which likely made them underpowered to demonstrate any significant difference in outcome measures between groups . therefore , further clinical prospective studies and randomized controlled trials with larger sample sizes are required to provide compelling scientific - based evidence of the influence of the undersized drilling technique on the primary and also on the secondary implant stability and healing potential of bone .
when evaluating what the impact of using the osteotome in implant bed preparation on primary and/or secondary implant stability is , only one rct and two clinical observational studies [ 48 , 50 ] were selected .
. found positive association between using the osteotome technique and the primary implant stability .
this increase in primary stability could be due to changes in the micromorphology of peri - implant trabecular bone caused by apicolateral condensation by osteotome .
so , the primary stability is enhanced in this low density bone maybe due to increase in its density .
in contrast , padmanabhan and gupta demonstrated a statistically significant higher primary stability for implants placed with conventional drilling technique than those placed with osteotome in the maxillary anterior region ( p < 0.05 ) .
the too small sample size ( n = 5 ) in this study to provide any reliable evidence and methodological differences might be responsible for this contrasting result compared with the abovementioned two .
with respect to the influence of osteotome technique on secondary implant stability , there was no significant influence of using osteotome on secondary implant stability when compared with conventional drilling technique in the two selected studies [ 48 , 49 ] , six months and three months after the surgery , respectively .
on the other hand , one article showed a statistically significant higher secondary stability for implants placed with osteotome technique than those placed with the conventional drilling technique during the entire 12-week observation period .
although a direct comparison among the three studies was not possible due to different implant brands used , different recipient sites , and due to different surgeon 's experience , an earlier significant increase of secondary stability in the osteotome group in markovi et al . study compared with padmanabhan and gupta and shayesteh et al .
first : as different surgeon 's hands conducted these studies , maybe in padmanabhan and gupta and shayesteh et al . studies , excessive loads were exerted on the bone by osteotome ; and provided that loads of more than 20 mpa , which might be anticipated during use of osteotomes , could displace bone marrow spaces and disturb the blood supply , the bone needs more time to form new spaces for angiogenesis and to repair this microdamaged bone .
study , the lateral bone compression might be within the physiological range and as such may have stimulated bone healing probably by activating the trauma - dependent repair mechanism known as regional acceleratory phenomenon , unlike the usual process of bone regeneration in the control group .
so this might interpret why secondary stability was higher for osteotome technique compared with conventional technique in this study .
second : provided that secondary stability is not only influenced by surgical technique but also by implant surface characteristics , the enhanced surface characteristics of implants used in the markovi et al .
study compared with padmanabhan and gupta and shayesteh et al . might be more able to detect a significant difference between the two techniques .
when evaluating whether using piezosurgery in implant bed preparation could influence the primary and/or secondary implant stability , just one rct was found .
it demonstrated that there was no real difference in primary stability when implants were placed following piezoeletric technique versus the conventional twist - drill technique .
however , it found a statistically significant higher secondary stability for piezogroup than the control group .
a possible interpretation of the earlier shifting from a decreasing to an increasing stability pattern in ultrasonic preparation sites , when compared with the traditional drilling technique , could derive from the cleaning effect of piezosurgery , microvibrations , and the cavitation effect of saline solution could result in effectively removing bony debris and tissue remnants deriving from site preparation , exposing marrow spaces , and favoring a rapid migration of osteoprogenitor cells into the fresh wound .
however , the results of this study can not be generalized because of some of limitations .
variables such as the single operator 's surgical technique , the limited numerosity of the sample , and the choice of the surgical site ( limited to the lateral maxilla ) must be taken into account .
also , the implants were not yet loaded and it can not be stated whether the finding may have a prognostic value for long - term stability of the implants procedure . therefore , further rcts using a larger sample size and longer follow - ups are necessary in order to confirm or refute these findings , and , thus , benefit from the possible clinical advantages of piezosurgery in immediate and early loading protocols for dental implant therapy . when assessing the influence of flapless procedure on primary and/or secondary implant stability , just one observational clinical study was selected .
concluding from this study , there was positive association between the flapless technique and the primary and secondary implant stability at three months after surgery . interpreting this finding
, it can be assumed that raising a mucoperiosteal flap and having the bone denuded during a certain time causes a postsurgical reaction and may have an impact on the bone remodeling around the implant . while the opposite occurs with flapless procedure where the bone remains covered by the periosteum ; this may increase vascularity of the peri - implant mucosa , which furthermore appeared to be free from signs of inflammation . despite that primary and secondary implant stability
were observed in slight favor of the flapless method in this study , we can not generalize this finding because of single operator 's surgical technique , the choice of the surgical site ( limited to complete edentulous maxilla ) , and because the implants were not yet loaded and it can not be stated whether the finding may have a prognostic value for long - term stability of the implants . when evaluating
whether the use of low - level laser therapy ( lllt ) to stimulate the osteotomy bone could influence the primary and/or secondary implant stability , only one rct was conducted .
it concluded that there was no evidence of any effect of irradiating bone osteotomies with infrared wavelengths on either primary or secondary implant stability within 12-week follow - up in the posterior mandible .
this finding could be explained by a hypothesis that the effect of the laser could have been masked by the high initial stability attained .
this high initial stability can be attributed not only to the bone quality ( type ii bone in the posterior mandible ) but also to the implant geometry used in this study .
thus , additional lllt may have little impact macroscopically . however , it is important to point out that outcomes of this study are limited to the specific methodology and results may differ in different bone conditions and implants when using different lllt protocols with other methodologies and different lengths of follow - up .
in addition , the small sample size of this trial is another limitation . to provide objective assessment of implant stability ,
three methods were chosen to assess implant stability in this review : the resonance frequency method , which generated the isq value , the percussion method , which generates the ptv value , and the insertion torque measurement that provided the it value in ncm . despite that the periotest has been the subject of criticism as a result of its poor sensitivity and the insertion torque method
allows a single measurement of primary stability and can not be used for evaluating secondary stability , the three methods were chosen to cover the maximum number of clinical studies on this subject and to avoid subjectivity . although
ptv , and periotest were used as key words , none of the selected articles used this method to assess primary or secondary stability .
although this systematic review aimed to verify the influence of different surgical techniques on primary and/or secondary stability of dental implants , it was also possible to extract some data concerning the implant dimensions , implant macrodesign , and the bone density from the selected articles .
. discovered an important influence of implant diameter on primary implant stability ( p < 0.05 ) .
. showed no significant effect of implant diameter and length on primary and secondary stability .
since implant shape , design , and surface characteristics are important for primary stability , most of the selected articles in this review standardized the implant marco- and microdesign except one , which demonstrated that self - tapping implants achieved greater primary and secondary stability at 12-week than non - self - tapping implants with conventional bone drilling technique ( p < 0.05 ) .
also , because there is a positive association between primary implant stability and bone mineral density of the receptor site , most of the selected studies in this review utilized one specific surgical site of the arch to minimize the effect of bone density on stability .
one of the selected articles reported strong correlations between bone density and primary implant stability values ( isq and it ) .
with respect to the influence of gender factor on primary stability , alghamdi et al . and katsoulis et al .
revealed significantly higher isq values for men . despite the relative positive association found between primary and/or secondary implant stability and some of the aforementioned surgical techniques ,
the methodological quality and control of bias of the studies need to be improved to produce stronger evidences .
a priori calculation for the sample size was undertaken in only two studies [ 49 , 53 ] .
inclusion and exclusion criteria for the sample selection were clearly defined in only five studies [ 11 , 32 , 49 , 50 , 53 ] .
in addition , blinding of outcome assessors were mentioned by the authors in only three of the included studies [ 11 , 50 , 53 ] .
finally , confounders were not considered for analysis in three studies [ 32 , 49 , 52 ] .
consequently , the quality assessment and control of bias ranked five articles as moderate and just three as high .
first , the search was limited to english - language publications , which may have introduced a publication bias and excluded other relevant articles .
however , such an exclusion may not considerably change the overall estimate of treatment effects .
second , the quality assessment and control of bias ranked five articles as moderate as assessed by the methodological checklist for prognostic studies developed by the national institute for health and clinical excellence of the united kingdom .
third , most of the selected articles had small or very small sample sizes , with relatively short follow - ups .
fourth , the inclusion of nonrandomized controlled clinical trials ( ccts ) in the analysis may have introduced a bias .
however , it was postulated that ccts can complement the evidence provided by rcts , particularly when rcts are not of a high quality .
these conclusions are based on few studies with small or very small sample sizes , relatively short follow - ups , moderate methodological quality , and being sometimes judged to be at moderate risk of bias , therefore they should be viewed with great caution.there is a weak evidence suggesting that undersized drilling technique could enhance the primary implant stability in sites of poor bone density.there is still a lack of evidence about the influence of undersized drilling technique on secondary implant stability.there is a weak evidence suggesting that using the osteotome technique to prepare implant beds in poor bone density could enhance the primary and secondary implant stability.there is a weak evidence suggesting that ultrasonic implant site preparation by piezoelectric inserts does not affect the primary mechanical stability but could fasten the bone healing process and increase the secondary implant stability , earlier than the traditional drilling technique.there is a weak evidence suggesting that flapless procedure could enhance the primary and secondary implant stability.there is insufficient evidence supporting or confuting the efficacy of irradiating bone osteotomies with infrared wavelengths for enhancing the primary or secondary stability of the implants .
there is a weak evidence suggesting that undersized drilling technique could enhance the primary implant stability in sites of poor bone density .
there is still a lack of evidence about the influence of undersized drilling technique on secondary implant stability .
there is a weak evidence suggesting that using the osteotome technique to prepare implant beds in poor bone density could enhance the primary and secondary implant stability .
there is a weak evidence suggesting that ultrasonic implant site preparation by piezoelectric inserts does not affect the primary mechanical stability but could fasten the bone healing process and increase the secondary implant stability , earlier than the traditional drilling technique .
there is a weak evidence suggesting that flapless procedure could enhance the primary and secondary implant stability .
there is insufficient evidence supporting or confuting the efficacy of irradiating bone osteotomies with infrared wavelengths for enhancing the primary or secondary stability of the implants .
more properly designed , rcts with at least 1-year follow - up after implant loading are needed to understand the influence of undersized drilling , the osteotome technique , the piezosurgery , the flapless , and the low - level laser therapy on primary and secondary stability of implants placed particularly in low density bone . at this time , we could revise the existing loading protocols in this poor - quality bone dealing with these suggested surgical techniques .
Output:
| background .
a number of surgical techniques for implant site preparation have been advocated to enhance the implant of primary and secondary stability . however , there is insufficient scientific evidence to support the association between the surgical technique and implant stability . purpose .
this review aimed to investigate the influence of different surgical techniques including the undersized drilling , the osteotome , the piezosurgery , the flapless procedure , and the bone stimulation by low - level laser therapy on the primary and/or secondary stability of dental implants .
materials and methods .
a search of pubmed , cochrane library , and grey literature was performed .
the inclusion criteria comprised observational clinical studies and randomized controlled trials ( rcts ) conducted in patients who received dental implants for rehabilitation , studies that evaluated the association between the surgical technique and the implant primary and/or secondary stability .
the articles selected were carefully read and classified as low , moderate , and high methodological quality and data of interest were tabulated . results .
eight clinical studies were included then they were classified as moderate or high methodological quality and control of bias .
conclusions .
there is a weak evidence suggesting that any of previously mentioned surgical techniques could influence the primary and/or secondary implant stability . |
PubmedSumm118654 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: the number of patients with type 2 diabetes has rapidly and continuously increased in recent years and has become a global burden .
identification of a high - risk population is one of the most important steps in the development of effective and efficient prevention strategies .
obesity is the most common risk factor for type 2 diabetes , and a vast amount of literature has reported on interventions aiming to reduce obesity .
the effectiveness of lifestyle intervention for diabetes prevention has been confirmed by large , randomized , controlled trials in both western countries [ 13 ] and asian countries [ 47 ] .
the subjects of these studies were at high risk for developing diabetes , being obese , and/or having impaired glucose tolerance .
all of these studies definitely succeeded in preventing diabetes , while weight reduction patterns differed between asian and western countries .
studies in asian countries showed a preventive effect with a smaller weight reduction ( 0 to 2.5 kg / year ) [ 6 , 7 ] than those in western countries ( 4.2 to 7.0 kg / year ) [ 2 , 3 ] . these results reflect obvious differences in baseline body mass index ( bmi ) among different regions .
the target population in preventive research trials usually has a bmi of 30 kg / m in western countries and about 25 kg / m in asian countries .
recent global epidemiological meta - analysis has shown that bmi is strikingly lower in asian populations compared with oceania , australasia , europe , and north america . among developed countries ,
kg / m ) and japanese females have nearly the lowest mean female bmi ( 21.4 kg / m ) . moreover , japanese patients with diabetes characteristically have a relatively low bmi .
focusing on obesity would therefore be a less efficient method of identifying high - risk individuals in asian countries than in western countries , and it is necessary to focus on risk factors other than obesity .
etiologically , type 2 diabetes results from a complicated combination of genetic and environmental factors .
individuals genetically predisposed to type 2 diabetes therefore represent an important target for preventive strategies .
some studies have suggested that the japanese are genetically predisposed to developing diabetes because they have a higher frequency of some diabetes susceptibility genes than caucasians [ 1113 ] .
a recent study reported a diabetes susceptibility gene specific to lean ( bmi < 24 kg / m ) japanese people .
these findings suggest that genetic considerations are especially important in diabetes prevention strategies for the japanese .
family history is a well - known risk factor for type 2 diabetes and has been used to screen high - risk populations [ 1517 ] from both genetic and environmental viewpoint .
offspring of patients with type 2 diabetes have a higher risk of developing the disease since they are likely to share the same genetic predispositions and have similar lifestyle habits as their parents . individuals with an affected first - degree relative have a 2.3- to 5.5-fold higher risk of developing type 2 diabetes , independent of sex , age , race / ethnicity , bmi , and other demographic characteristics . family history is thus a useful tool for detecting genetically high - risk populations in this postgenomic era [ 20 , 21 ] .
some studies have already revealed positive effects of lifestyle interventions for dietary habits in relatives of diabetic patients [ 2224 ] , and of increasing recognition of diabetes risk .
these results suggest that intervention for relatives would be effective if delivered in a useful way . however , it is difficult for medical professionals to reach the relatives of patients in both research and clinical settings , because the relatives rarely visit hospitals unless they get ill .
one way to contact relatives to offer general genetic counseling and promote preventive behavior is to utilize patient as intermediaries between medical professionals and relatives [ 26 , 27 ] .
unfortunately , using patients in this role had not been demonstrated to be effective in diabetes .
the rates of participation in lifestyle intervention programs offered to relatives through patients have been reported to be disappointingly low ( 513.5% ) [ 24 , 28 ] , and advice about lifestyle modification given by patients was reported to have no effect on their offspring 's preventive behavior .
these results suggest that it is difficult to motivate relatives to implement preventive lifestyle changes , especially through patients .
it is therefore essential for diabetes preventive strategies to establish a way to contact relatives directly , in order to provide lifestyle intervention programs and maintain compliance in such programs .
one of the most common opportunities for medical professionals to make contact with the offspring of patients with type 2 diabetes is at the time of a medical checkup . in japan , employers have a legal obligation to allow their employees an annual health checkup .
additionally , the japanese ministry of health , labour and welfare enacted the specific health checkup ( shc ) in 2008 that aims to identify individuals at high risk for the development of metabolic syndrome in both employed and nonemployed populations .
the shc is mainly undertaken by municipal governments , who will be penalized by central government if they can not achieve the target consultation rate ( e.g. , 65% by 2012 ) .
subjects are usually asked during the checkup if they have a family history of common diseases such as stroke , cardiovascular disease , infectious disease , lipidemia , or diabetes .
unfortunately , this information about family history has not been fully utilized as a screening tool for implementation of intervention to prevent type 2 diabetes [ 30 , 31 ] .
the current study therefore aims to screen for high - risk individuals using information about family history , and then contact subjects directly to provide preventive intervention . as mentioned above , it is difficult to motivate the relatives of patients with type 2 diabetes to implement preventive lifestyle changes .
for high - risk individuals to become actively involved in prevention , recognition of the risk of acquiring the disease is crucial [ 32 , 33 ] .
information about disease susceptibility is sometimes a psychological burden for high - risk people , especially those who are genetically predisposed .
genetic risk education should therefore be provided as a component of genetic counseling , which is the medical / psychosocial process that disease predisposed subjects are advised of the consequences , nature , and management of an inherited disorder , even though previous research has shown that such information mainly has a favorable effect on psychological issues [ 25 , 35 ] .
however , genetic counseling often seems to be less feasible in the health checkup setting since it takes more time than usually available at an outpatient clinic .
it was therefore essential to develop a counseling tool which enables medical professionals to explain genetic diabetes susceptibility and diabetes prevention quickly and adequately .
the authors developed a six - page booklet based on the traditional health belief model , which can be utilized for brief genetic counseling including risk education about type 2 diabetes .
in the current study , brief genetic counseling by a certified genetic counselor was provided to subjects using the booklet .
then the current study tried to investigate the effect of that genetic counseling on participant 's compliance to the lifestyle intervention . to maintain compliance with lifestyle interventions
it is particularly difficult to motivate the offspring of type 2 diabetic patients to receive preventive intervention , as they are generally healthy and have other demands on their time .
previous research has indicated that healthy subjects prefer correspondence format programs to face - to - face format programs for the delivery of health education .
. the printed format may be particularly advantageous as the material is more likely to be read , saved , and perceived as personally relevant than information presented on a cd - rom [ 37 , 38 ] .
even though telephone programs are more personal and immediate and involve more natural language than mail programs , both telephone and mail programs are effective in reducing the health risk status of participants .
mail programs place fewer time constraints on people and are more readily available than internet programs .
mail format , which is easily available , is therefore considered suitable for maintaining compliance with preventive interventions for potentially high - risk relatives . to provide effective lifestyle interventions ,
medical professionals should comprehensively assess subjects and deliver individualized information , which can be achieved efficiently using computer - tailored health education [ 41 , 42 ] .
computer - tailored lifestyle intervention is a promising health education technique , particularly for ( printed ) nutrition education and is well suited to modification of complex health - related behaviors ( e.g. , by providing feedback ) .
previous studies have shown that computer - tailored intervention involving questionnaires and tailored messages can result in behavioral changes and weight loss in healthy people [ 4446 ] .
furthermore , computer - tailored interventions have emerged as a new and cost - effective type of health promotion program because they enable personalization of health education without the high cost of personal counseling .
the computerized behavioral program is therefore expected to be an effective and feasible intervention tool .
the objective of this parallel , three - group trial is to investigate the effects of printed computer - tailored lifestyle intervention on favorable lifestyle change , and the effects of genetic counseling about prevention and hereditary risk of type 2 diabetes on the compliance to the life style intervention .
this study is a parallel , three - group , randomized , controlled trial investigating the effects of printed computer - tailored lifestyle intervention ( li ) on favorable lifestyle change , and the effects of genetic counseling ( gc ) about prevention and hereditary risk of type 2 diabetes on the compliance to the life style intervention .
data collected at preintervention , immediately post - gc ( baseline ) , and at 1 week and 3 , 6 , and 12 months post - gc will be analyzed .
the design , conduct , and reporting of the study adhere to the consolidated standards of reporting trials ( consort ) guidelines .
subjects were included if they had a first - degree relative with type 2 diabetes and were aged 3060 years .
those who were already diagnosed with type 2 diabetes or metabolic syndrome , or were already receiving lifestyle intervention , were excluded .
subject recruitment was carried out in the medical checkup department of a general hospital in tokyo .
subjects were randomized into three groups : genetic counseling and lifestyle intervention ( gc&li ) , lifestyle intervention ( li ) , and control .
after written consent was obtained , subjects underwent genetic counseling with a certified genetic counselor .
the counseling session used the booklet developed by the authors , which has been described elsewhere .
briefly , the booklet consists of four sections , each reflecting a core element of the health belief model , with the following information provided in each section .
information on the drastic increase in the number of diabetic patients , and the implications of genetic - environmental interactions .
causes of diabetes , such as genetic predisposition , high - fat foods , and/or a sedentary lifestyle [ 11 , 49 ] .
information on genetic predisposition , decreased insulin secretion , and the decreased insulin sensitivity caused by a high - fat meal .
advice that individuals with an affected first - degree relative have a 2.35.5-fold higher risk of developing type 2 diabetes since such individuals seem to have similar genetic predisposition and lifestyle .
advice that the risk of acquiring diabetes can be modified by a low - fat diet and increased physical activity ( pa ) [ 50 , 51 ] .
a summary of concrete methods to modify diet and pa , and a recommendation to refer to professionals for individualized prevention [ 50 , 51 ] .
lifestyle intervention in this study features tailored and concrete lifestyle recommendations in a computer - based , non - face - to - face format .
the intervention will use lifestyle intervention support software for diabetes prevention ( liss - dp ) .
contents of liss - dp are developed based on lifestyle intervention protocol for secondary or tertiary prevention in type 2 diabetes patients , which has been developed by one of authors [ 52 , 53 ] .
the intervention strategy consists of the following processes : ( 1 ) lifestyle and background data collection by self - administered questionnaire ; ( 2 ) generation of tailored recommendations ; ( 3 ) output of tailored recommendations ; ( 4 ) delivery of the recommendations via mail .
( 1 ) lifestyle and background data collection by self - administered questionnaireliss - dp requires information about the subject 's current diet and pa to identify risky or favorable behavior .
the questionnaire is based on two measurement scales : evaluation scale for self - management behavior related to physical activity of type 2 diabetic patients ( es - smbpa-2d ) and dietary self - management behavior questionnaire ( dsbq ) ; which were developed by the authors .
these scales measure dietary and pa self - management behaviors in diabetic patients and consist of 32 and 91 items , respectively .
we modified these scales to assess preventive dietary and pa behaviors in healthy relatives of patients with type 2 diabetes .
items were chosen for each scale according to the following criteria : dietary behavior shown in previous research to have a significant relationship with total energy intake [ 52 , 53 ] , pa behavior shown to have a significant relationship with energy expenditure , and important preventive behaviors as judged by an expert panel . as a result , a lifestyle assessment questionnaire consisting of 53 items was developed , with 15 items assessing recommended dietary behaviors ( rd ) ( table 1 ) , 21 items assessing recommended physical activity behaviors ( rp ) ( table 2 ) , 16 items assessing nonrecommended dietary behaviors ( nd ) ( table 3 ) , and a single item assessing nonrecommended physical activity behavior ( np )
questionnaires ask the subjects to indicate the frequency of each behavior on five - point scale which will be converted to a numerical score : never ( 0 ) , rarely ( 1 ) , sometimes ( 2 ) , often ( 3 ) , or always ( 4 ) .
liss - dp requires information about the subject 's current diet and pa to identify risky or favorable behavior .
the questionnaire is based on two measurement scales : evaluation scale for self - management behavior related to physical activity of type 2 diabetic patients ( es - smbpa-2d ) and dietary self - management behavior questionnaire ( dsbq ) ; which were developed by the authors .
these scales measure dietary and pa self - management behaviors in diabetic patients and consist of 32 and 91 items , respectively .
we modified these scales to assess preventive dietary and pa behaviors in healthy relatives of patients with type 2 diabetes .
items were chosen for each scale according to the following criteria : dietary behavior shown in previous research to have a significant relationship with total energy intake [ 52 , 53 ] , pa behavior shown to have a significant relationship with energy expenditure , and important preventive behaviors as judged by an expert panel . as a result , a lifestyle assessment questionnaire consisting of 53 items was developed , with 15 items assessing recommended dietary behaviors ( rd )
( table 1 ) , 21 items assessing recommended physical activity behaviors ( rp )
( table 2 ) , 16 items assessing nonrecommended dietary behaviors ( nd )
( table 3 ) , and a single item assessing nonrecommended physical activity behavior ( np ) ( table 3 ) .
questionnaires ask the subjects to indicate the frequency of each behavior on five - point scale which will be converted to a numerical score : never ( 0 ) , rarely ( 1 ) , sometimes ( 2 ) , often ( 3 ) , or always ( 4 ) .
( 2 ) generation of tailored recommendationsliss - dp will be used to assess each subject 's lifestyle behaviors and generate individualized recommendations according to the following algorithms ( figure 2 ) .
first , subjects will be divided into four groups according to their combination of risk factors , sex , and physical activity level : male / high - pa group ( a ) , male / low - pa group ( b ) , female / high - pa group ( c ) , and female / low - pa group ( d ) .
a high physical activity level is defined according to the national health promotion policy ( healthy japan 21 ) as 30 min of moderate physical activity 2 days / week .
liss - dp will then select the items to be assessed in each risk group .
in addition to these selected items , subjects with obesity - related risk factors , high bmi , and/or large waist circumference will be assessed using items which have a relationship with obesity . cut - off point for each obesity - related risk factor was set based on those of national screening program ( shc , mentioned previously ) .
if subjects answer never or rarely to one of the selected rd or rp items , that item will be identified as a behavior which the subject should aim for .
always to one of the selected nd , that item will be identified as a behavior which the subject should refrain from . if subjects answer
always to np item , it will be also identified as a behavior which the subject should refrain from . additionally , if subjects answer often or
always to one of the rd or rp items , that item will be identified as a behavior which should be continued .
liss - dp will be used to assess each subject 's lifestyle behaviors and generate individualized recommendations according to the following algorithms ( figure 2 ) .
first , subjects will be divided into four groups according to their combination of risk factors , sex , and physical activity level : male / high - pa group ( a ) , male / low - pa group ( b ) , female / high - pa group ( c ) , and female / low - pa group ( d ) .
a high physical activity level is defined according to the national health promotion policy ( healthy japan 21 ) as 30 min of moderate physical activity 2 days / week .
liss - dp will then select the items to be assessed in each risk group .
in addition to these selected items , subjects with obesity - related risk factors , high bmi , and/or large waist circumference will be assessed using items which have a relationship with obesity .
cut - off point for each obesity - related risk factor was set based on those of national screening program ( shc , mentioned previously ) .
if subjects answer never or rarely to one of the selected rd or rp items , that item will be identified as a behavior which the subject should aim for .
if subjects answer often or always to one of the selected nd , that item will be identified as a behavior which the subject should refrain from . if subjects answer
always to np item , it will be also identified as a behavior which the subject should refrain from .
additionally , if subjects answer often or always to one of the rd or rp items , that item will be identified as a behavior which should be continued .
( 3 ) output of tailored recommendationsdietary and pa behaviors which should be aimed for , refrained from , or continued by the subject will be printed on a lifestyle advice sheet consisting of computer - based lifestyle recommendations and a free - comment section for use by the clinical diabetes educator.the lifestyle recommendations consist of five sections .
sections i and ii provide positive feedback about favorable behaviors to increase self - awareness about preventive behaviors .
rd item(s ) and rp item(s ) identified as behavior(s ) which should be continued will be indicated as follows.section iyour current behaviors(s ) shown below are effective for maintaining a favorable total energy intake .
be confident in continuing these actions.section iiyour current behavior(s ) shown below are effective for maintaining a favorable physical activity level .
be confident in continuing these actions.dietary behavior(s ) which should be aimed for will be identified in section iii as follows.section iiithe behavior(s ) shown below are recommended for maintaining a favorable total energy intake .
please incorporate these into your daily life to achieve favorable dietary habits.both dietary and pa behavior(s ) which the subject should refrain from will be identified in section iv as follows . section ivthe behavior(s ) shown below would cause an excess of calorie intake .
please refrain from these behaviors.physical activity behavior(s ) which should be aimed for will be identified in section v as follows .
please incorporate these into your daily life to achieve favorable physical activity levels.following the lifestyle recommendations , a clinical diabetes educator will write advisory comments .
the advisory comments will mention general recommendations for lifestyle change , and integrate the individual recommendations .
after the second intervention , changes in lifestyle since the previous data collection will be also be shown in the advisory comments .
dietary and pa behaviors which should be aimed for , refrained from , or continued by the subject will be printed on a lifestyle advice sheet consisting of computer - based lifestyle recommendations and a free - comment section for use by the clinical diabetes educator .
sections i and ii provide positive feedback about favorable behaviors to increase self - awareness about preventive behaviors .
rd item(s ) and rp item(s ) identified as behavior(s ) which should be continued will be indicated as follows.section iyour current behaviors(s ) shown below are effective for maintaining a favorable total energy intake .
be confident in continuing these actions.section iiyour current behavior(s ) shown below are effective for maintaining a favorable physical activity level .
your current behaviors(s ) shown below are effective for maintaining a favorable total energy intake .
your current behavior(s ) shown below are effective for maintaining a favorable physical activity level .
dietary behavior(s ) which should be aimed for will be identified in section iii as follows.section iiithe behavior(s ) shown below are recommended for maintaining a favorable total energy intake
both dietary and pa behavior(s ) which the subject should refrain from will be identified in section iv as follows .
physical activity behavior(s ) which should be aimed for will be identified in section v as follows .
the advisory comments will mention general recommendations for lifestyle change , and integrate the individual recommendations .
after the second intervention , changes in lifestyle since the previous data collection will be also be shown in the advisory comments .
( 4 ) delivery of recommendations via mailthe lifestyle advice sheet will be sent to subjects via mail .
subjects allocated to the control group will receive conventional routine care during the study period , including disclosure of medical checkup results and general information about diabetes prevention .
the genetic counseling booklet and three lifestyle advice sheets will be sent to subjects in the control group after the end of the study period .
the primary outcomes of this study are changes in total energy intake , fat - energy ratio , and physical activity levels between baseline and the end of the intervention period .
the questionnaires include a dietary measurement scale ( modified - ministry of health and welfare - food questionnaire ( m - mhw - fq ) ) and a physical activity scale ( international physical activity questionnaire ( ipaq ) ) .
the m - mhw - fq has been shown to be a reliable method of calculating energy intake and fat - energy ratio .
the ipaq has been shown to be a valid method of assessing physical activity across various life activities , including during leisure activities [ 5759 ] .
biomedical data collected from hospital records at baseline and at 12 months ( age , bmi , waist circumference , and levels of hba1c , fasting blood glucose , triglyceride , ldl cholesterol , and hdl cholesterol ) will be used in the analyses .
subjects ' perception and recognition about diabetes and attitude towards its prevention will be assessed before gc session ( baseline for these variables ) and 1 week after the session in order to evaluate the effect of gc on subjective aspect .
data collected at the time of recruitment and at 1 week and 3 , 6 , and 12 months after recruitment will be used in this study .
background characteristics will be assessed at the time of recruitment : whether he / she has impaired glucose tolerance , abnormalities of lipid metabolism , hypertension or hyperuricemia ; living status ; occupational status ; educational status .
baseline values for outcome measures related to lifestyle behaviors will be collected at 1 week after recruitment because participants must spent more than 15 minutes to answer the questionnaire for lifestyle assessment , and it is infeasible to order them about completing it during medical checkup .
all questionnaires will be sent and returned via mail , except for the questionnaire completed at the time of recruitment .
we will phone participants or mail a reminder if the questionnaire has not been returned until deadline , four weeks after each questionnaire had been sent .
the intervention in preliminary study was conducted in mail - delivered style , similar to current study , while advice sheet was made by a dietician and a medical fitness therapist in handwriting .
after three - times intervention during 6 months , 1.0 sd change was observed in primary outcome ( total energy intake ) .
intervention in current study is computer - based , it means less tailored to individual participant than preliminary study .
so observed effect in this study is expected to be modest compared to preliminary study .
we calculated the necessary sample size to be 64 per study arm to detect a moderate effect size ( 0.5 sd ) , with 80% power at the 5% significance level . assuming a dropout rate of 10% from the results of a previous similar study [ 37 , 46 ] , 72 participants are needed for each arm .
therefore , this study will be conducted with a single - blinded design ; group allocation was blinded to the clinical diabetes educator and researcher who will analysis the data .
once questionnaire will be sent back to research institute , one of researchers immediately check the validity of responses .
if missing value or outlying response was found , researcher would phone participant to correct these incomplete response . to avoid human error in data input ,
two research assistants independently input all the responses into computer . after checking one dataset against another one and confirming perfect matching
we will summarize continuous variables using means and standard deviations , and categorical variables using counts and percentages .
similarly , the effects of li will be investigated by comparing the li and control groups .
differences between groups in secondary outcomes at each assessment point will be analyzed by the student 's t - test for continuous variables or the mann - whitney u test for ordinal variables . in all tests
, a p value of < 0.05 by two - tailed test will be considered significant .
analysis will be performed using sas 9.2 ( sas institute , cary , nc , usa ) software for windows .
all study protocols have been approved by the institutional review board of the school of medicine , the university of tokyo and social insurance chuo general hospital .
figure 1 shows a flow diagram of subject enrollment and initial data collection . during the recruitment period
of these , 322 ( 59.8% ) declined to participate in the study , leaving 216 subjects who were randomly allocated to one of three groups and completed initial data collection : gc&li ( n = 75 ) , li ( n = 70 ) , and control ( n = 71 ) .
the baseline questionnaire about lifestyle behaviors was completed by 69 subjects ( 92% ) in the gc&li group , 63 subjects ( 90% ) in the li group , and 57 subjects ( 80% ) in the control group .
overall , 61.1% of subjects are male , and the mean age is 45.8 7.8 years .
the mean bmi indicates that subjects are in the nonobese range ( 22.5 3.0 kg / m ) .
mean energy intake was 1777.4 420.8 kcal / day , and fat / energy ratio was 28.9 6.6% .
one of novel challenges in this study is to bring genetic approach into conventional medical checkup system . at present ,
genetic screening using information about variants of known disease susceptibility genes which has been identified by genome - wide association study is technically available .
however , genotype profiling seems to be less useful for individual risk prediction because most of diabetes susceptible genes show not more than 1.4-fold increased risk of type 2 diabetes .
several large - scale epidemiological study have shown that genotype adds only a small amount of additional information to risk prediction models that include common risk factors such as obesity , sex , and family history [ 6265 ] . in addition , people who get genomic profiling and intervention based on their genotype do not modify their lifestyle or attitude towards prevention much , at least in the short term [ 66 , 67 ] . therefore , family history is still a useful , clinically available , costless , and etiologically robust diabetes screening tool in this postgenomic era .
the current study presents a preventive strategy targeting individuals with a positive family history of type 2 diabetes but without obesity .
this population surely has a risk of developing diabetes , but tends to be overlooked in the current medical checkup system .
the interventions undertaken in this study have been developed based on a framework for self - management interventions for secondary or tertiary prevention in patients with type 2 diabetes .
conventional face - to - face lifestyle intervention has been modified to effectively motivate subjects and be easily accepted by them .
genetic counseling including discussion of the hereditary risk of diabetes and of risk management by modification of environmental factors was undertaken to try to motivate subjects . the computer - based and non - face - to - face interventions attempt to address barriers regarding initiation and maintenance of lifestyle modifications in subjects , while also maintaining clinical feasibility .
previous intervention studies recruiting adult offspring of patients with type 2 diabetes have reported much lower participation rates ( 513.5% ) [ 24 , 28 ] .
direct recruitment at a medical checkup department is therefore a more effective method for implementation of prevention strategies in individuals with a family history of diabetes than indirect recruitment through patients .
however , the acceptance ratio is still not very high , with more than half of eligible subjects refusing to participate .
this might cause a sampling bias which could weaken the external validity of the study .
the average health status of study participants is normal , with both bmi and waist circumference in the normal range .
total energy intake at baseline was 29.8 kcal / kg / day , which is already in the favorable target range defined in the da qing study ( 2530 kcal / kg / day ) . in conclusion ,
the current study has achieved a relatively successful recruitment of subjects with a family history of type 2 diabetes but without other common risk factors such as obesity .
the interventions designed for this study have specific features which are theoretically advantageous for interventions in subjects who have a genetic predisposition for disease but are currently healthy , and are clinically feasible .
the preventive strategies used in this study could therefore provide a novel solution to the numbers of high - risk individuals not participating in preventive programs , if found to be effective .
Output:
| relatives of type 2 diabetic patients are at a high risk of developing type 2 diabetes and should be regarded as target of intervention for diabetes prevention . however , it is usually hard to motivate them to implement preventive lifestyle changes , because of lack of opportunity to take advises from medical professionals , inadequate risk perception , and low priority for preventive behavior .
prevention strategy for them therefore should be highly acceptable and suited for them .
the parallel , three - group trial is now being conducted to investigate the effects of genetic counseling and/or a computerized behavioral program on the prevention of type 2 diabetes in that population .
the preventive strategies used in this study could provide a novel solution to the numbers of genetically high - risk individuals , if found to be effective .
the objective of this paper is to describe the background , protocol , and baseline patient characteristics of the trial . |
PubmedSumm118655 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input:
a 54-year - old woman with diabetic chronic end - stage nephropathy ( glomerular filtration rate , < 15 mlmin1.73 m ) who was receiving continuous ambulatory peritoneal dialysis and had a history of heart failure with subacute bacterial endocarditis treated 6 months beforehand was admitted for subarachnoid hemorrhage . on admission ,
the patient was fully conscious with a grade 1 world federation of neurological societies score .
a computed tomography ( ct ) brain scan showed a modified fisher grade iii subarachnoid hemorrhage , and a subsequent catheter angiogram confirmed a ruptured right posterior communicating artery aneurysm .
primary coil embolization of the aneurysm was performed with complete obliteration with 105 ml of the nonionic , iso - osmolar contrast medium iodixanol ( visipaque , nycomed amersham , new jersey ) .
mol / l and 11 to 13 md / dl , respectively ( after dialysis ) . by day 15
, the patient remained drowsy with a glasgow coma score of 14 of 15 and a montreal cognitive assessment score of 17 of 30 .
preoperative echocardiography showed a left ventricular ejection fraction of 48% with no evidence of intracardiac valvular vegetations .
the patient was considered at risk of developing ventriculoperitoneal shunt infection or peritonitis as a result of her continuous ambulatory peritoneal dialysis .
there were also concerns that ventriculoatrial shunting could precipitate a recurrent episode of bacterial endocarditis .
ventriculopleural shunting was also considered , but her history of recurrent cardiogenic pleural effusion that required tapping meant placement was prohibitive .
an alternative means of csf diversion was therefore required . after consent was obtained , with the patient 's full understanding of the novel nature of the procedure , implantation of a vs shunt
contrast - enhanced computed tomography ( ct ) brain scan ( a ) that resolved after placement of a ventriculosternal shunt ( b and c ) .
six - month 3-dimensional reconstructed ct scan of the upper thorax showing the distal catheter in situ ( d and e ) .
the patient was administered 2 g cefazolin intravenously and was positioned supine with her head rotated 15 contralateral to the side of shunt implantation . after skin preparation and draping ,
an l - shaped skin incision was made at the sternal notch with the longitudinal limb measuring 3 cn , parallel to the anterior border of the sternocleidomastoid muscle ( figures 2a-2c ) .
the tendinous insertions of the sternocleidomastoid muscle were displaced laterally to expose the superior border of the manubrium .
an 8-mm - wide bore , 4-cm - deep tunnel through the cortical bone of the manubrium into its cancellous matrix was created with a high - speed drill ( midas rex legend , medtronic , minneapolis , minnesota ; figures 2a , 2d , and 2e ) . a ventricular silastic catheter ( medtronic neurosurgery , goelta , california )
was inserted via a right parietal burr hole in the usual manner , and a subcutaneous tunnel was created from the scalp wound to the sternal notch wound .
a programmable differential pressure valve ( ps medical strata ii , medtronic neurosurgery ) was then connected to the ventricular catheter .
another silastic catheter ( 3-mm outer diameter ) with 3 side perforations was inserted into the sternal tunnel and anchored to the tendinous insertions of the contralateral sternocleidomastoid muscle with nonabsorbable 3 - 0 silk sutures .
the catheter was subsequently looped to accommodate lateral rotation neck movement ( figure 2f ) . attaching the catheter to a syringe elevated 15 cm above the heart allowed 10 ml normal saline to be absorbed intraosseously over 3 minutes .
the catheter was subsequently connected to the distal end of the shunt valve , with shunt patency confirmed when the valve reservoir refilled after compression .
both the scalp and sternal notch wounds were closed in layers with absorbable 3 - 0 polyglactin-910 ( vicryl , ethicon , somerville , new jersey ) and 3 - 0 nylon sutures .
schematic showing the proposed course of a ventriculosternal ( vs ) shunt with a recommended length of manubrial tunnel of 4 cm ( a ) . an l - shaped skin incision for a right - sided shunt with the sternal notch marked ( b )
drilling of the manubrial tunnel parallel to the long axis of the manubrium at its midline ( d ) .
angiocatheter placement to confirm the length of the tunnel and intraosseous absorption of normal saline ( e ) .
placement of shunt silastic catheter with a loop anchored to the contralateral tendinous insertions of the sternocleidomastoid muscle with 3 - 0 silk ( f , blue arrow ) .
her ambulatory ability improved , and she could walk with minimal assistance by postoperative day 5 . a week after shunting , the patient 's montreal cognitive assessment score improved to 28 of 30 .
a ct scan showed a reduction in ventricular size and the sternal wound healed well without evidence of fluid collection , osteomyelitis , or keloid formation ( figures 1b and 1c ) .
a postoperative 6-month ct thoracic scan showed that the distal catheter remained within the intraosseous tunnel without csf accumulation in the mediastinal cavity ( figures 1d and 1e ) .
three years after vs shunt implantation , the patient continued to be free of shunt - related complications with no deterioration of cardiac function .
a 54-year - old woman with diabetic chronic end - stage nephropathy ( glomerular filtration rate , < 15 mlmin1.73 m ) who was receiving continuous ambulatory peritoneal dialysis and had a history of heart failure with subacute bacterial endocarditis treated 6 months beforehand was admitted for subarachnoid hemorrhage . on admission ,
the patient was fully conscious with a grade 1 world federation of neurological societies score .
a computed tomography ( ct ) brain scan showed a modified fisher grade iii subarachnoid hemorrhage , and a subsequent catheter angiogram confirmed a ruptured right posterior communicating artery aneurysm .
primary coil embolization of the aneurysm was performed with complete obliteration with 105 ml of the nonionic , iso - osmolar contrast medium iodixanol ( visipaque , nycomed amersham , new jersey ) .
mol / l and 11 to 13 md / dl , respectively ( after dialysis ) . by day 15
, the patient remained drowsy with a glasgow coma score of 14 of 15 and a montreal cognitive assessment score of 17 of 30 .
preoperative echocardiography showed a left ventricular ejection fraction of 48% with no evidence of intracardiac valvular vegetations .
the patient was considered at risk of developing ventriculoperitoneal shunt infection or peritonitis as a result of her continuous ambulatory peritoneal dialysis .
there were also concerns that ventriculoatrial shunting could precipitate a recurrent episode of bacterial endocarditis .
ventriculopleural shunting was also considered , but her history of recurrent cardiogenic pleural effusion that required tapping meant placement was prohibitive .
an alternative means of csf diversion was therefore required . after consent was obtained , with the patient 's full understanding of the novel nature of the procedure , implantation of a vs shunt
contrast - enhanced computed tomography ( ct ) brain scan ( a ) that resolved after placement of a ventriculosternal shunt ( b and c ) .
six - month 3-dimensional reconstructed ct scan of the upper thorax showing the distal catheter in situ ( d and e ) .
the patient was administered 2 g cefazolin intravenously and was positioned supine with her head rotated 15 contralateral to the side of shunt implantation . after skin preparation and draping ,
an l - shaped skin incision was made at the sternal notch with the longitudinal limb measuring 3 cn , parallel to the anterior border of the sternocleidomastoid muscle ( figures 2a-2c ) .
the tendinous insertions of the sternocleidomastoid muscle were displaced laterally to expose the superior border of the manubrium .
an 8-mm - wide bore , 4-cm - deep tunnel through the cortical bone of the manubrium into its cancellous matrix was created with a high - speed drill ( midas rex legend , medtronic , minneapolis , minnesota ; figures 2a , 2d , and 2e ) . a ventricular silastic catheter ( medtronic neurosurgery , goelta , california )
was inserted via a right parietal burr hole in the usual manner , and a subcutaneous tunnel was created from the scalp wound to the sternal notch wound .
a programmable differential pressure valve ( ps medical strata ii , medtronic neurosurgery ) was then connected to the ventricular catheter .
another silastic catheter ( 3-mm outer diameter ) with 3 side perforations was inserted into the sternal tunnel and anchored to the tendinous insertions of the contralateral sternocleidomastoid muscle with nonabsorbable 3 - 0 silk sutures .
the catheter was subsequently looped to accommodate lateral rotation neck movement ( figure 2f ) . attaching the catheter to a syringe elevated 15 cm above the heart allowed 10 ml normal saline to be absorbed intraosseously over 3 minutes .
the catheter was subsequently connected to the distal end of the shunt valve , with shunt patency confirmed when the valve reservoir refilled after compression .
both the scalp and sternal notch wounds were closed in layers with absorbable 3 - 0 polyglactin-910 ( vicryl , ethicon , somerville , new jersey ) and 3 - 0 nylon sutures .
schematic showing the proposed course of a ventriculosternal ( vs ) shunt with a recommended length of manubrial tunnel of 4 cm ( a ) . an l - shaped skin incision for a right - sided shunt with the sternal notch marked ( b )
drilling of the manubrial tunnel parallel to the long axis of the manubrium at its midline ( d ) .
angiocatheter placement to confirm the length of the tunnel and intraosseous absorption of normal saline ( e ) .
placement of shunt silastic catheter with a loop anchored to the contralateral tendinous insertions of the sternocleidomastoid muscle with 3 - 0 silk ( f , blue arrow ) .
her ambulatory ability improved , and she could walk with minimal assistance by postoperative day 5 . a week after shunting , the patient 's montreal cognitive assessment score improved to 28 of 30 .
a ct scan showed a reduction in ventricular size and the sternal wound healed well without evidence of fluid collection , osteomyelitis , or keloid formation ( figures 1b and 1c ) .
a postoperative 6-month ct thoracic scan showed that the distal catheter remained within the intraosseous tunnel without csf accumulation in the mediastinal cavity ( figures 1d and 1e ) .
three years after vs shunt implantation , the patient continued to be free of shunt - related complications with no deterioration of cardiac function .
our experience demonstrates that vs shunting can be a feasible , safe , and durable csf diversionary procedure .
ventriculomastoid shunting to the mastoid antrum , the nosik6 operation , was proposed > 60 years ago but failed to gain popularity because of its high rates of infection and csf rhinorrhea .
researchers using swine and human cadaveric models recently proposed that the diploic space of the skull or the iliac crest could also be a potential osseous site , but their findings were not translated clinically.7,8 by adopting a similar theory of intraosseous fluid infusion , tubbs et al4 first conceived the possibility of vs shunting .
intraosseous fluid infusion in prehospital trauma and critical care settings is a time - tested procedure when peripheral venous access can not be established.9 a variety of resuscitation fluids such as crystalloids , blood products , and medications can be successfully delivered to the vascular space by intraosseous means .
it contains a rich plexus of venous sinusoids that drain into longitudinal central haversian canals linked to one another by a system of volkmann canals and exit bone via emissary or nutrient veins.9 from the numerous osseous entry sites available , the sternum is ideal for shunt implantation for several reasons .
its midline position and proximity to the skull render implantation less difficult and reduce the risk of shunt dislodgement compared with the humerus or the iliac crest.7 in adults , the sternum also retains a relatively large portion of vascular red marrow compared with the tibia or humerus , allowing better csf absorption.9 finally , the site is drained by the internal mammary and azygos veins , which have been shown to impart intraosseous pressures comparable to central venous pressure.10 an exploratory study describing the feasibility of vs shunting using human cadaveric , live rhesus monkey , and swine animal models concluded that the manubrium can be a viable csf receptacle.4 tubbs et al4 demonstrated that up to 30 l water could be infused over an hour through the cannulated manubrium in 5 fresh human cadavers without noticeable fluid collections in the cranial , thoracic , or abdominal cavities .
the group then performed sternal intraosseous normal saline infusions in live rhesus monkeys for 24 hours , and extravascular fluid accumulation could not be detected on subsequent magnetic resonance imaging.4 to verify the practicality of vs shunting in larger animals , tubbs et al finally performed the procedure on 2 adult nonhydrocephalic pigs . at 2 weeks , both pigs were stable and did not display signs of infection . on autopsy
, there was no evidence of osteomyelitis or csf extravasation.4 the critical stages of vs shunt implantation are the tunneling of the manubrium and the final insertion of the distal catheter tip .
preparation of the manubrium was performed easily with a high - speed neurosurgical drill , but one should be cognizant of regional anatomy .
the trapezoid - shaped adult manubrium has a mean length , breadth , and thickness of 5.3 0.4 , 4.9 0.6 , and 1.2 0.1 cm , respectively.11 we advise that the maximal length of the tunnel should be limited to 4 cm to avoid inadvertent penetration of the posterior cortex and entry into the superior mediastinum ( figure 2a ) . in that event
, the procedure may need to be abandoned because csf entering the mediastinal cavity could exert undue pressure on its contents .
the surgeon should also be aware that intraosseous vascular access has potential , although uncommon , complications with an overall rate of < 1%.10 from a recent meta - analysis of 18 studies that adopted modern infusion devices , no infectious complications were described in > 1300 procedures.10 despite a high incidence of fat or marrow embolism , ranging from 89% to 100% observed in canine animal models , most embolisms were subclinical and rarely resulted in hemodynamic instability.12 the lack of yellow , fat - laden bone marrow within the sternum makes this site less likely to be a source of embolism .
there is also a risk of causing acute iatrogenic fractures or , with long - term infusion , osteomalacia and subsequent pathological fractures .
however , such cases are rare , and animal studies have reported normal bone growth and marrow cellular differentiation.13 prospective human radiographic studies also failed to detect delayed bone growth in pediatric patients with a history of tibial infusions.14 the vs shunt was implanted for 3 years , and the patient did not experience any complications . to the best of our knowledge , no other patient has been exposed to such longstanding intraosseous fluid infusion , which reflects the potential durability of this procedure .
inadvertent entry into the superior mediastinum could lead to brachiocephalic artery injury as a result of its more superficial and midline location .
other superficial structures at risk of injury include the brachiocephalic veins and vagus nerves , but they are often located beyond the lateral border of the manubrium .
another concern is keloid scarring , especially in young patients or those with a positive family history or darker skin complexions .
finally , as with conventional ventriculoatrial shunts , immune complex mediated glomerulonephritis can also theoretically occur with vs shunts .
we propose that patients with tracheostomies , a previous history of sternal fractures or sternotomy , osseous abnormalities such as severe osteoporosis or osteogenesis imperfecta , regional infection , evidence of right - to - left cardiac shunting ( with a consequential risk of fat or marrow paradoxical embolism ) , and a history of shunt nephritis should not be considered for vs shunting .
vs shunting can be an effective alternative in treating selected adult patients with hydrocephalus when other conventional csf shunt terminus sites are contraindicated .
we believe that wider adoption of this novel technique may confirm its role as a safe , durable csf diversionary procedure .
the authors have no personal financial or institutional interest in any of the drugs , materials , or devices described in this article .
the authors have no personal financial or institutional interest in any of the drugs , materials , or devices described in this article .
the authors have taken the results of our original feasibility study and applied them clinically with good results .
additional target absorptive receptacles such as the sternum will broaden the options available to the neurosurgeon who treats hydrocephalus .
long - term studies in large cohorts are now necessary to investigate the application of this novel approach .
moreover , future comparison studies will direct the surgeon toward the best anatomic option for the terminal part of the cerebrospinal fluid diversionary shunt .
the authors present an unusual shunting option in which the distal portion of the shunt was inserted into the manubrium .
the case in question is the not uncommonly seen situation in which there are poor options for distal insertion .
the authors present their logic and details of the manubrial shunting option and nicely describe the potential complications and patient outcome .
although commonplace use of this method is unlikely , it adds another option to the neurosurgeon 's armamentarium in dealing with difficult shunting situations .
Output:
| background : conventional cerebrospinal fluid diversion such as ventriculoperitoneal or ventriculoatrial shunting for the management of hydrocephalus is one of the commonest neurosurgical procedures .
however , in selected patients , surgical options are limited when relative contraindications for these operations exist . a patient who underwent ventriculosternal shunting , a novel procedure ,
is presented with durable and successful outcomes.objective:to demonstrate the feasibility , durability , and safety of ventriculosternal shunting for the management of hydrocephalus.methods:a patient with end - stage renal failure and heart failure with recurrent pleural effusion suffered from post subarachnoid hemorrhage communicating hydrocephalus . because of the need for continuous ambulatory peritoneal dialysis and the risk of introducing excessive cardiac preloading , conventional shunting was relatively contraindicated .
ventriculosternal shunting was performed by adopting the cancellous matrix of the sternum as the anatomic receptacle for intraosseous cerebrospinal fluid absorption .
after placement of the ventricular catheter in the usual manner , the distal end was inserted into the sternum.results:there was demonstrable clinical and radiological improvement in hydrocephalus by ventriculosternal shunting .
cerebrospinal fluid intraosseous absorption by this novel procedure translated into both physical and cognitive recovery .
the procedure was tolerable , effective , and durable , with the patient suffering no complications 3 years after the procedure.conclusion:ventriculosternal shunting for the management of hydrocephalus is a feasible , safe , and durable surgical treatment option for selected patients when conventional procedures are contraindicated.abbreviation:vs , ventriculosternal |
PubmedSumm118656 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: typhoid fever is an acute systemic disease caused by the ingestion of food or water contaminated with the organism salmonella enterica subsp .
the infection occurs worldwide and is still an important public health problem in many developing countries .
it is estimated to cause more than 21 million illnesses and 216,000 deaths worldwide annually .
the clinical manifestations of typhoid fever are usually non - specific , such as sustained fever with fatigue , headache , abdominal pain , vomiting , or anorexia .
various organs , including the liver , have been involved in the course of typhoid fever , resulting in a wide spectrum of presentations .
the usual pathological site of salmonella infection is the lymphoid tissue of the gastrointestinal tract .
hematogenous dissemination of the organism or its endotoxin results in systemic involvement that can affect almost all major organs , including the liver , central nervous system , gall - bladder , kidney , lung , and heart .
liver involvement is commonly observed in patients with typhoid fever , but severe hepatic involvement with a clinical feature of acute hepatitis is a rare complication .
a previously healthy 39-year - old man was admitted from pasinler / erzurum , where there was a limited outbreak of salmonella typhi infections in the summer of 2010 .
seven days before admission , he had a temperature of 39.2c , with a headache , fatigue , loss of appetite , and a non - productive cough .
general physical and systemic examinations were unremarkable , except for fever and mild tenderness in right upper abdominal region . on investigation , the patient 's hemoglobin level was 15.2 g / dl , total leukocyte count was 7400/l ( polymorphs 58% , lymphocytes 31.8% , monocytes 10% , basophils 0.1% , and eosinophils 0.1% , ) , and platelet level was 128,000/l .
liver tests showed increase in aspartate transaminase ( ast ) ( 277 u / l ; range 437 ) , alanine transaminase ( alt ) ( 657 u / l ; range 042 ) , gamma - glutamyl transferase ( ggt ) ( 322 u / l ; range 550 ) , alkaline phosphatase ( alp ) ( 1111
u / l ; range 0270 ) , total bilirubin ( 1.15 mg / dl ; range 0.21.1 ) , and direct bilirubin ( 0.96 mg / dl ; range 0.000.30 ) .
serological and viral markers of acute viral hepatitis were negative ( markers for the hepatitis c virus , hepatitis a virus , hepatitis b virus , hepatitis e virus , cytomegalovirus , and epstein - barr virus ) .
the c - reactive protein ( crp ) level was 199 mg / dl ( range 06 ) .
changes in laboratory results after the patient 's hospitalization are given in table 1 .
table 1hematological and biochemical profile of patient.normal range30.09.201004.10.201006.10.201011.10.201022.12.2010hemoglobin13.515.5 ( g / dl)15.213.61416.2leukocyte count4.810.8 ( 103/l)7.46.79.78.7platelet130400(103/l)128190443269ast437 u / l2772332486424alt042 u / l65733842514841alp0270 u / l111111441787675260ggt550
u / l32227126717630total bilirubin0.21.1 mg / dl3.154.355.372.460.25direct bilirubin0.00.3 mg / dl2.963.134.602.030.01crp06 mg / l19938.920.612.73.25ast , aspartate transaminase ; alt , alanine transaminase ; alp , alkaline phosphatase ; ggt , gamma - glutamyl transferase ; crp , c - reactive protein
hematological and biochemical profile of patient .
ast , aspartate transaminase ; alt , alanine transaminase ; alp , alkaline phosphatase ; ggt , gamma - glutamyl transferase ; crp , c - reactive protein abdominal sonography resulted in normal findings .
the magnetic resonance ( mr ) cholangiography findings requested as a result of the consultation with the gastroenterology clinic were also normal .
the patient was treated initially with ceftriaxone ( cef ) 2 g given intravenously once daily .
on the fourth day of the treatment , blood culture yielded the growth of s.typhi .
the isolate was susceptible to cefotaxime and cef , but resistant to ciprofloxacin and levofloxacin .
then , after treatment with cef on the sixth day , the patient was feeling better , and we observed the progressive improvement of liver enzymes and crp .
in addition , blood and stool cultures were tested , respectively , after 10 days of cef , and were negative .
salmonella typhi infection is still a major health problem in tropical and developing countries . in the developed world , enteric fever is uncommon and predominantly a disease of returning travelers .
typhoid fever is often associated with abnormal biochemical tests on the liver , but severe hepatic involvement with a clinical feature of acute hepatitis is a rare complication .
he documented eight cases with hepatomegaly and jaundice out of 1500 cases of typhoid fever .
the extent of liver involvement in typhoid fever may be a dramatic presentation with a picture indistinguishable from viral hepatitis in 126% of cases .
our case had elevated serum alanine and aspartate transaminase , alkaline phosphatase , and gamma glutamyl transferase levels ; these features can not been distinguished from those of acute viral hepatitis .
four cases whose acute renal failure and hepatitis complications had been followed were presented in a study conducted in south africa , and the ast value in these cases was found to be a maximum of 830 u / l . as the course of this case was cholestatic , ast increased to a maximum of 248 u / l . in another study ,
data from 27 patients with typhoid hepatitis were compared to those of 27 acute viral hepatitis cases . in this study ,
the alt increase of the transfused cases of patients with typhoid hepatitis was less than that found in those with viral hepatitis and ast ; the increases in alp levels were found to be more apparent .
again , while bilirubin levels were found to be higher in patients with acute hepatitis , they were lower in patients with salmonella hepatitis .
no pathology could be determined in abdomen ultrasonography ( usg ) or mr cholangiography . in an extensive examination made on typhoid hepatitis in thailand , it was noted that cases similar to acute hepatitis clinic were seen quite rarely ; and it was emphasized that virulence of the factor , delay in treatment , and the patient 's general state of health being bad may cause this picture to emerge .
typhoid nodules characterized by an apparent hyperplasia in reticuloendothelial cells were mentioned in the pathological examination .
it was claimed that typhoid hepatitis pathogenesis was multi - factored and endotoxins , local inflammatory response , and/or immune response of the host can be effective .
the recent demonstration of intact s.typhi in the liver tissue of patients with typhoid fever suggests that organisms are phagocytosed by the reticuloendothelial system but overcome the cells ' killing action and produce hepatic injury by liberating cytotoxic substances in situ .
acetaminophen is known to cause toxic hepatitis mostly in a closed dependent manner and with hepatocellular damage .
the occurrence of hepatitis approximately 1 week after the use of low dose of acetaminophen ( 1500 mg / day ) in the subject and with the treatment specific to salmonella ( ceftriaxone ) which is thought to have caused this picture , improvement in cholestatic hepatitis case ( cholestasis enzymes and bilirubin levels had reduced ) with the symptoms of the patient have made us diagnose salmonella induced cholestatic hepatitis on the subject .
no certain toxic hepatitis is usually expected with the use of acetaminophen in daily therapeutic doses and it is too rare in cholestatic type ( excluding idiosyncratic cases ) . in a recent study about the use of acetaminophen in daily therapeutic doses and covering more than 2500 patients where the patients were followed for more than one year , it was stated that only 181 of the patients had their alt values above normal limits . in the study ,
three times height of alt and the height of bilirubin level were not determined together in any of the patients .
also , none of the patients ' alt levels were found higher than 10 times of normal limits . as our patient used normal therapeutic dose of acetaminophen ( 1500 mg / day ) ,
the cholestatic form of the hepatitis incurred and alp , ggt , alt and direct bilirubin ( dbil ) rise being in the foreground , alt levels rising approximately 15 times more the higher limit of the normal as well as the visible improvement in the cholestasis table after ceftriaxone treatment made us think of salmonella induced cholestatic hepatitis in the patient .
the prognosis is usually good , as salmonella hepatitis responds well to specific antibiotic therapy .
the clinical course can be severe , with a mortality rate as high as 20% , particularly with delayed treatment or in patients with other complications of salmonella infection .
fluoroquinolones ( e.g. , ciprofloxacin ) , which have been available since the 1980s , have become a mainstay of therapy for invasive salmonellosis .
reduced ciprofloxacin sensitivity has become increasingly prevalent and is associated with high rates of clinical and microbiological failure .
therefore , alternative antimicrobials , including third generation cephalosporins and azithromycin , are increasingly used as first - line therapy .
there was quinolone resistance in our case as well , and the patient was treated by ceftriaxone .
as enteric fever is a common infection , the recognition of salmonella hepatitis is of clinical importance . when patients from an endemic or outbreak area present acute febrile hepatitis with or without diarrhea , typhoid fever should be a consideration .
blood culture and serological tests for salmonella in these patients will lead to early diagnosis and appropriate treatment .
Output:
| salmonella infection occurs worldwide and is still an important public health problem in many developing countries .
the infection can affect almost all major organs including the liver .
severe hepatic involvement with a clinical feature of acute hepatitis is a rare complication . in this paper , a 39-year - old male with acute cholestatic typhoid hepatitis
is presented .
the case had a tender hepatomegaly and elevated serum alanine and aspartate transaminase , alkaline phosphatase , and gamma glutamyl transferase levels ; these features can not been distinguished from those of acute viral hepatitis .
serological and viral markers of acute viral hepatitis were negative .
no pathology could be determined in abdomen ultrasonography ( usg ) or magnetic resonance ( mr ) cholangiography . as enteric fever
is a common infection , the recognition of salmonella hepatitis is of clinical importance .
when patients from an endemic or outbreak area present acute febrile hepatitis , typhoid fever should be a consideration . |
PubmedSumm118657 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: personality traits are individual characteristics that influence cognition , emotions , and behaviour , leading to adaptive or maladaptive responses .
cloninger have proposed the temperament and character inventory ( tci ) , which includes four temperament ( novelty seeking ( ns ) , harm avoidance ( ha ) , reward dependence ( rd ) and persistence ( p ) ) and three character ( self - directedness ( sd ) , cooperativeness ( c ) , self - transcendence ( st ) ) scales .
tci represents a useful instrument to measure personality in the light of cloninger s psychobiological model of personality .
temperament dimensions are highly heritable and stable throughout life and are correlated to emotional reactions and habits .
in contrast , cloninger originally proposed that the character dimensions were weakly heritable and influenced by social learning .
however , their successive study showed that the heritability of the character dimensions ( 2745% ) is comparable to that of the temperament dimensions ( 3042% ) .
personality features may predispose to psychiatric disorders , mainly affective and anxiety disorders , and viceversa , some personality traits could be a consequence or complication of chronic debilitating disorders such as chronic depression or anxiety disorders . among personality traits , the ha dimension of the tci [ 5 - 11 ] and the neo personality inventory dimension neuroticism
[ 12 - 14 ] , which is highly related to ha [ 15 , 16 ] , have been positively correlated with anxiety and depression . on the contrary , other personality dimensions , such as sd [ 10 , 11 , 17 , 18 ] ,
c [ 6 , 19 ] and ns , in particular the subscale ns1 [ 7 , 20 , 21 ] , have been negatively correlated with depression and/or anxiety .
mostly , the above mentioned studies have investigated the relationship of personality traits with depression and anxiety disorders in clinical samples .
only few studies [ 18 , 21 - 23 ] have been undertaken in the general population .
the aim of the present study is to replicate previous evidences about the association of personality traits with anxiety and depression in a general italian population sample .
in order to constitute a general population control sample for genetic studies of psychiatric disorders we recruited in brescia , italy , 418 people through different sources ; such as university of brescia , local newspaper advertisement , fatebenefratelli s hospitals employees , and local elderly associations .
san giovanni di dio - brescia , italy ) and participants gave written informed consent .
all subjects were assessed for life - time dsm - iv axis i disorders through the mini - international neuropsychiatric interview ( m.i.n.i . ) .
the seven cloninger s dimensions of personality were assessed by the italian version of tci , a 240-item , true - false , self - report questionnaire . in order to avoid biases in the filling of the tci , subjects who obtained a score lower than 27/30 at the mini mental state examination ( m.m.s.e . )
the association between mental disorders and tci dimensions was analysed by the multivariate analysis of variance , using tci scores as dependent variables , diagnoses as independent variable , and age and education as covariates ( mancova ) .
chi - square ( 2 ) test was used to evaluate the association between groups and categorical variables . with these parameters we had a sufficient power ( 0.95 ) to detect a small effect size ( d = 0.09 ) for the ha dimension .
all analyses were conducted using the spss statistical software , version 12.0 ( spss inc .
sociodemographic characteristics of the sample are shown in table 1 . based on the assessment made by the mini ,
the whole sample consisted of 266 ( 81% ) subjects without and 61 subjects ( 19% ) with life - time dsm - iv axis i disorders . in the disordered group , 40 subjects had major depressive disorder , 3 subjects had panic disorder , 21 had generalized anxiety disorder , 6 had dysthymia , 1 had bipolar disorder , 1 had alcohol abuse , and 1 substance abuse ( the total number exceeds the number of subjects due to the presence of comorbidity ) .
since the aim of the study was to investigate the relationship between unipolar major depression and anxiety disorders with personality traits , we excluded from the analysis participants with other diagnosis ( 4 subjects ) .
thus , subjects were divided in two groups ; one composed of healthy subjects ( 266 ) and one of subjects with depressive and/or anxiety disorders life - time ( 57 subjects ) .
the two groups were not homogeneous both for age ( healthy subjects 49.45 15.86 ( meansd ) year - old ; disordered group 54.14 16.04 year - old ; f = 4.10 ; p = 0.04 ) , sex ( 55% and 75% females in the healthy and disordered groups respectively ; 2 = 7.89 , p=0.005 ) and education ( healthy subjects 12.9 5.00 years ; disordered group 11.53 4.40 years ; f = 3.93 ; p = 0.048 ) .
the mean scores for tci dimensions sorted by dsm - iv diagnoses are shown in table 2 .
the disordered group showed significantly higher scores than healthy subjects in ha ( harm avoidance ) and lower scores in sd ( self - directedness ) as well as in ns1 ( exploratory excitability ) .
because the control and disordered groups were not homogeneous for sex , we carried out also a mancova analysis for females and males separately , in order to evaluate if the results could be affected by gender .
gender did not affect the results observed in the unsplitted sample for ha and sd .
however , after splitting the sample by gender , sd5 and c2 were significantly lower only in the female disordered group as compared to the healthy one ( data not shown ) .
in the present study , we investigated the correlation of depressive and anxiety disorders with personality traits in a general italian population sample .
the main finding is that subjects with life - time depressive and/or anxiety disorders showed high scores in ha and sd dimensions , as well as in ns1 subscale .
there has long been a strong interest in understanding the relationship between maladaptive personality traits and axis i psychopathology , and this paper fits within this very rich and extensive literature . indeed ,
our results are in agreement with previous data , mainly from clinical samples and general population , which show a strong association of ha and sd dimensions with depressive and anxiety disorders [ 5 - 11 , 17 - 19 , 23 ] .
our data provide further evidence that specific personality traits are associated with a lifetime history of depression or anxiety disorders .
longitudinal studies [ 5 , 7 , 9 , 26 ] that examined tci scores during course of recovery from depression found changes in various temperament and character dimensions , except for ha . even if ha score significantly decreased during the time , it remains higher than healthy controls at the time of full remission ; this supports the hypothesis that ha can be considered a partly state dependent trait and , overall , it acts as premorbid factor that predicts the vulnerability to burden of depression .
therefore , our study supports the hypothesis that the ha dimension of tci could represent a marker for emotional vulnerability to depression and anxiety disorders .
subjects with high ha could be described as pessimistic worriers who tend to anticipate harm and failure .
they are nervous , insecure , unassertive , negativistic , or pessimistic even in situations that do not normally worry other people . on the other hand , low sd scorers often experience distress in defining setting and pursuing meaningful goals and values in everyday life .
thus , tci sd represents a marker of executive functions that protect a person from depression .
therefore , in agreement with the beck s negative cognitive triad theory of depression , sensitivity to life events with negative thoughts about the self , the world , and the future , generated by dysfunctional beliefs , could make one vulnerable to anxiety and mood disorders .
finally , we found a significant and negative correlation of life - time mood and anxiety disorders with the ns1 subscale .
this finding are consistent with previous studies demonstrating , in depressed patients , the tendency to avoid novelty and active exploration of unfamiliar environment [ 7 , 20 ] .
several socio - demographic factors emerged to be associated with increased risk for depression and anxiety disorders .
low levels of education , loneliness situation and female gender , had a significant prevalence of lifetime history of these diseases .
the main limitation of this study was the relatively small sample of population recruited , which did not allow the examination of the relationship between personality traits with depressive and anxiety disorders separately .
in addition , the non - significant finding such as the comparison to current versus those with a past history could be non - significant because of the small sample size available .
however , differently from previous reports where diagnoses were made by self - report screenings [ 18 , 21 - 23 ] , in this study participants were assessed with screened the mini interview by trained psychologists , avoiding the possible bias produced by self - report screenings .
nonetheless , the recruitment of the subjects could origins a selection bias for the fact that the recruited volunteers that gave a positive response to participate to a research study could have a particular personality profile .
our data are consistent with previous evidence about the correlation between ha and sd personality dimensions and ns1 subscale with mood and anxiety disorders .
the current study purposed to replicate the findings of previous tci studies in an italian sample .
this work supports and confirms the hypothesis that individual differences in personality structure and development have a strong influence on the risk of several forms of psychopathology .
clearly , the findings that are being replicated here are neither particularly surprising nor controversial , and it has been replicated many previous times , nevertheless , replication of earlier findings in different population can represent a useful contribution to the literature .
Output:
| personality traits provide a description of individual emotional and cognitive processes that modulate thoughts , feelings and behaviour .
few studies have investigated the relationship of personality traits with depression and anxiety in the general italian population .
the aim of the present study was to replicate previous evidences about the association of personality traits with anxiety and depression in a general italian population sample.we recruited 418 volunteers through different sources ; such as university , newspaper advertisement , hospital , and elderly association .
327 subjects accepted to participate to the study and were screened with the mini - international neuropsychiatric interview ( m.i.n.i . ) in order to assess dsm - iv axis i disorders and with the temperament and character inventory ( tci ) in order to measure personality traits.based on the assessment made by the mini , the whole sample consisted of 266 ( 81% ) subjects without and 61 subjects ( 19% ) with life - time dsm - iv axis i disorders .
volunteers with life - time anxiety and depressive disorders showed high scores in harm avoidance as well as low scores in self - directedness and in the novelty seeking subscale
exploratory excitability.our results support previous evidences showing that personality traits , in particular harm avoidance and self - directedness , could represent markers of vulnerability for depression and anxiety disorders . |
PubmedSumm118658 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: nephronophthisis ( nphp ) is an autosomal recessive cystic kidney disease and a leading genetic cause of established renal failure ( erf ) in children and young adults .
nphp literally means disappearance of nephrons , which alludes to its histopathology , with interstitial fibrosis and corticomedullary cysts replacing normal renal tissue .
the incidence of nphp varies worldwide ; it was previously identified to range from 1 in 50,000 to 1 in 900,000 [ 35 ] ; however , these figures are likely to underrepresent the true frequency , since molecular testing has diagnosed nphp in adults presenting with advanced chronic kidney disease ( ckd ) [ 6 , 7 ] .
the prevalence of nphp amongst the paediatric population with erf is 5% in the usa and 6.5% in the uk [ 8 , 9 ] . early presenting symptoms in children with nphp
usually develop at around 6 years of age and include polyuria , nocturia or secondary enuresis , polydipsia , and lethargy ( secondary to anaemia ) .
these features are a consequence of salt wasting and an inability to concentrate urine ( < 400 mosm / kg early morning urine ) , implicating dysfunction of the renal cortical collecting duct .
renal ultrasound identifies normal or reduced kidney size , with increased echogenicity and corticomedullary cysts .
there is a less common infantile variant of nphp in which children reach erf by 3 years of age and have enlarged cystic kidneys on renal ultrasound .
there is a diffuse distribution of cysts within the kidneys of children with arpkd , and it is more often associated with liver cysts and fibrosis .
a diagnostic renal biopsy of nphp reveals a characteristic triad of tubular basement membrane disruption , tubulointerstitial nephropathy / fibrosis , and corticomedullary cysts [ 4 , 14 ] .
increasingly , molecular genetic testing is being utilised to diagnose nphp and avoid the need for a renal biopsy .
the most frequent anomaly is retinal degeneration ; other associated features and disorders include cerebellar vermis hypoplasia ( joubert syndrome ( js ) ) , occipital encephalocele ( meckel - gruber syndrome ( mks ) ) , hepatic fibrosis , situs inversus , bronchiectasis , and skeletal defects .
in addition to this apparent variability in the spectrum and severity of phenotype , nphp is genetically heterogenous . to date
mutations have been identified in 13 genes ( table 1 ) which collectively account for approximately 30% of patients .
the protein products of all of these genes localise on primary cilia and related structures ( basal bodies , centrosomes ) , resulting in a unifying hypothesis that cystic kidney diseases are ciliopathies . in this paper
, we will discuss the latest understanding in the molecular and cellular pathogenesis of nphp and suggest an appropriate management plan / screening programme for individuals and their families , particularly in view of the considerable clinical heterogeneity .
nphp is a recessive monogenic disorder , meaning that two mutations ( homozygous or compound heterozygous ) in a single gene are sufficient to cause disease .
thirteen genes have been identified in affected families with nphp ( table 1 ) , and these genes currently allow 30% of patients with nphp to be solved in terms of a molecular diagnosis .
these genes have been identified using positional cloning strategies and homozygosity mapping in consanguineous families .
nephrocystins , to the primary cilium / basal body led to recognition of nphp as a ciliopathy .
primary cilia are highly conserved , microtubule - based hair - like structures which extend from the apical surface of almost every epithelial cell .
they function in order to detect extracellular cues and mediate cellular signalling pathways ( discussed below ) .
ciliary genes are currently recognised as attractive candidates to evaluate when attempting to define the molecular cause of nphp in the presently undiagnosed 70% of patients . with this in mind , combined homozygosity mapping , ciliopathy candidate exome capture , and parallel sequencing
have recently been performed resulting in the successful identification of pathological mutations in the gene , serologically defined colon cancer antigen 8 ( sdccag8 ) , in families with nphp .
also recently , the targeted screen of the ciliary gene ttc21b revealed that its protein product , ift139 , is essential for retrograde intraflagellar transport .
ift139 interacts with ciliopathy proteins bbs4 and bbs8 , and pathogenic mutations in ttc21b were identified in patients with nphp and more severe related ciliopathies .
although the majority of currently known nphp genes produce proteins which localise to primary cilia / basal bodies / centrosomes , recent identification of an nphp - like locus in two affected families suggests that nphp genes may not be exclusively ciliary .
genome - wide homozygosity mapping identified pathogenic mutations in x - prolyl aminopeptidase 3 ( xpnpep3 ) , or nphpl1 ( nphp like 1 gene ) , of which the protein product localises to mitochondria .
although not currently identified in the primary cilium , xpnpep3 may influence cilia function through enzymatic cleavage of associated ciliary proteins . whilst homozygous mutations in the nphp genes can cause isolated nphp , mutations in the same gene
similarly , it would appear logical that the type of mutation may influence the phenotype .
for example , a missense mutation may cause isolated nphp or senior - loken syndrome ( sls , retinitis pigmentosa ) , whilst a truncating mutation could cause mks .
recently the effect of different mutations in nphp6 on clinical presentation has been eloquently reviewed .
. the concept of modifier genes has been recognised in patients with the related ciliopathy , bardet - biedl syndrome ( bbs ) , where pathogenic mutations in more than one gene have been detected , implicating a role for oligogenicity .
oligogenicity or triallelism , whereby a mutation in a third allele may exert an epistatic effect and modify the phenotype , has been described in nphp .
a brief description of each of the nphp genes , their encoded nephrocystin proteins , and any interacting protein partners is given below .
nphp1 was the first nphp gene identified and accounts for the majority ( 2025% ) of known cases of isolated nphp [ 23 , 24 ] .
recently adults presenting with signs of nphp and erf in two generations of a turkish family with no known consanguinity suggested a diagnosis of a dominant cystic kidney disease such as medullary cystic kidney disease ( mckd ) or perhaps a novel variant of dominant nphp .
however , identification of homozygous mutations in nphp1 in all affected family members revealed a pseudodominant inheritance of unknown cause as a consequence of unidentified consanguineous relationships .
the increased age at presentation with erf is atypical and is hypothesised to be a consequence of currently unknown modifier genes .
nphp1 mutations can also cause retinal and cerebellar phenotypes leading to sls and js .
oligogenicity has been reported in families with nphp , where mutations in both nphp1 and nphp3 , nphp1 and nphp4 , and nphp1 and the ciliopathy gene abelson helper integration site-1 ( ahi1 , the most frequently mutated gene in js ) have been detected .
mutations in both nphp1 and nphp6 have been identified in patients with nphp - related ciliopathies including sls and js .
this evidence of genetic interaction , known protein - protein interactions between various nephrocystins , combined with an awareness of other ciliary proteins such as bbsome functioning as a complex , makes it highly likely that several of the nephrocystins form a functional supramolecular complex within cells [ 17 , 20 ] .
nephrocystin-1 localises at cell - cell contacts including tight junctions , adherens junctions , and focal adhesions [ 42 , 43 ] .
nephrocystin-1 has also been identified at the transition zone / base of the primary cilium .
nephrocystin-1 interacts with various other proteins important in maintaining the cellular scaffolding or cytoskeleton including jouberin , ack1 , filamin a and b , tensin ( actin binding ) , -tubulin ( microtubule structure ) , and protein tyrosine kinase 2b ( ptk2b ) .
mutations in nphp2 are distinct because they cause infantile nphp , characterised by an earlier presentation of erf ( at approximately 3 years of age ) , with enlarged kidneys on ultrasound .
additional clinical features include cardiac anomalies ( situs inversus and ventricular septal defects ( vsd ) ) .
although nphp2 mutations are a rare cause of nphp compared to nphp1 , there has been intense research regarding the molecular / cellular pathogenesis of inversin .
inversin is located in the primary cilium and other subcellular sites in a cell - cycle dependent manner .
a previous work has suggested that inversin acts as a switch between canonical and non - canonical ( planar cell polarity ) wnt signalling .
when inversin is lost after nphp2 mutation , it was proposed that sustained canonical wnt signalling led to cell proliferation and random oriented cell division .
however , recent experiments in the inv mutant mouse model of nphp showed no difference in canonical wnt signalling compared to controls .
in addition to nephrocystin-1 , inversin interacts with calmodulin , catenins , -tubulin , and anaphase - promoting complex 2 [ 48 , 51 ] .
mutations in nphp3 are again a rare cause of isolated nphp ; however , they can cause a broad spectrum of phenotypes as shown in table 1 .
nephrocystin-3 colocalises with nephrocystin-1 and inversin in primary cilia , adherens junctions , and focal adhesions . the pcy mouse model of nphp displays cystic kidneys and responded to treatment with aquaretic agents / vasopressin-2-receptor antagonists .
nephrocystin-4 colocalises and interacts with nephrocystins 1 , 3 and inversin in primary cilia and associated appendages , adherens junctions , and focal adhesions [ 20 , 27 ] .
nephrocystin-4 also interacts with nephrocystin-8 [ 55 , 56 ] , -tubulin , breast cancer antioestrogen resistance 1 ( bcar1 ) , ptk2b , and the tight junction proteins pals1/patj
nephrocystin-5 contains two iq calmodulin binding sites ; the significance of its interaction with calmodulin is unclear .
it colocalises with nephrocystin-1 and nehrocystin-4 in the primary cilium , adherens junctions , and focal adhesions and interacts with nephrocystin-6 [ 30 , 58 ] .
nephrocystin-5 also complexes with the retinal ciliopathy gene retinitis pigmentosa gtpase regulator ( rpgr ) , explaining the frequent retinal phenotype .
mutations in nphp6 cause a full spectrum of extrarenal features with no apparent genotype - phenotype correlation .
it is the commonest genetic cause ( 21% ) of isolated congenital retinal degeneration , leber 's congenital amaurosis ( lca ) .
it was suggested that oligogenicity and the effect of modifier genes may account for some of the pleiotropy .
oligogenicity has been described in patients with homozygous nphp6 mutations and an additional heterozygous mutation in : nphp4 resulting in nphp or sls , nphp11 causing bbs or mks , and ahi1 causing js .
oligogenicity has also been identified in patients with sls and js as a consequence of a homozygous mutation in nphp1 and heterozygous mutation in nphp6 .
nphp6 interacts with and modulates the transcription factor atf4 , involved in camp - dependent renal cyst formation .
in addition to nephrocystin-5 , another protein interaction partner of nephrocystin-6 is coiled - coil and c2 domain protein ( cc2d2a ) . in zebrafish models of combined nphp6 and cc2d2a knockdown ,
there is synergy of the renal cystic phenotype , suggesting an epistatic , disease - modifying effect .
cc2d2a mutations cause js and mks ; however , they have not been identified in patients with isolated nphp [ 15 , 61 ] .
nphp7 is a rare cause of isolated nphp ; its protein product is a kruppel - like zinc - finger transcription factor , gli - similar protein 2 , which localises to the primary cilium and nucleus .
interestingly , a glis2 knockout mouse model showed an upregulation of genes promoting epithelial - to - mesenchymal transition and histological features of nphp including fibrosis .
this correlation of nephrocystin-7 with gli transcription factors links the pathogenesis of nphp to the hedgehog ( hh ) signalling pathway , which is essential for controlling tissue maintenance .
nphp8 mutations more frequently cause extrarenal manifestations such as cerebello - oculo - renal syndromes , js [ 32 , 56 ] , and mks than isolated nphp .
there appears to be some genotype - phenotype correlation with missense mutations causing lca , whilst truncating mutations cause the more severe disorder mks .
oligogenicity has been identified with a pathogenic homozygous mutation in nphp5 and heterozygous nphp9 mutation , which may behave as a modifying gene , in an individual with sls . in some patients with heterozygous nphp9 mutations ,
its protein product , never in mitosis a - related kinase 8 ( nek8 ) , colocalises with various nephrocystins in primary cilia , basal bodies , and centrosomes and appears to be important in regulating the cell cycle .
nek8 has been shown to interact with polycystin-2 ( autosomal dominant polycystic kidney disease ( adpkd ) protein ) , to regulate its expression and phosphorylation .
sdccag8 was recently identified as nphp10 by homozygosity mapping , ciliopathy candidate exome capture , and parallel sequencing .
twelve mutations were identified in ten families with nphp - related ciliopathies , in particular sls and bbs .
homozygous sdccag8 mutations account for 3.3% of cases of sls . its protein product , serologically defined colon cancer antigen 8 ( sdccag8 ) , colocalises at centrosomes and cell - cell junctions with nephrocystin-5 .
sdccag8 and nephrocystin-5 colocalise in the transition zone of photoreceptors which is likely of functional significance and correlates with the phenotype of sls .
sdccag8 interacts directly with the protein oral - facial - digital syndrome 1 ( ofd1 ) , although the functional significance of this is currently not clear , it is clearly of interest , as recessive mutations in ofd1 are an x - linked cause of the nphp - related ciliopathy js .
mutations in nphp11 are pleiotropic , having been identified in patients with nphp and liver fibrosis , extending to patients with related ciliopathies including js , mks , and coach syndrome ( cerebellar vermis hypoplasia , oligophrenia ( developmental delay ) , ataxia , coloboma , and hypotonia ) .
whilst oligogenicitiy has not been described , a patient with js and an isolated heterozygous nphp11 mutation has been identified , suggesting that triallelism and the role of nphp11 as a modifier gene is possible .
transmembrane protein 67 ( tmem67 ) or meckelin localises to the membrane of primary cilia and diffusely at basal and basolateral cell surfaces .
tmem67 interacts with several proteins including nesprin 2 , mks1 , and tmem216 which are important in maintaining cellular structure and mitigating centrosome migration , which is essential for ciliogenesis .
nphp - like 1 gene ( nphpl1 ) was recently identified in two consanguineous families with nphp by genome - wide homozygosity mapping .
this is a novel discovery because it is the first nphp gene identified whose protein product , x - propyl aminopeptidase 3 ( xpnpep3 ) , does not localise to primary cilia , basal bodies , or centrosomes .
instead , xpnpep3 localises in mitochondria ; however , it has been hypothesised that this enzyme may be able to interfere with cilia function by cleaving certain cilial proteins [ 17 , 35 ] .
mutations in ttc21b have recently been identified in families with isolated nphp and extrarenal manifestations including the ciliopathy , jeune asphyxiating thoracic dystrophy ( jatd ) .
interestingly , both causal mutations ( homozygous or compound heterozygous ) and modifier mutations ( heterozygous ) in ttc21b were identified in affected individuals .
oligogenicity was identified between ttc21b and several other ciliopathy genes . with regard to nphp
, triallelism was identified in a turkish family with mutations in both ttc21b and nphp4 .
the protein product of ttc21b is a retrograde intraflagellar transport protein ift139 , found in the primary cilium , and is essential for ciliary function .
oligogenicity has been described above for nphp1 , nphp5 , nphp6 , nphp8 , nphp9 , nphp11 , and ttc21b .
it has been hypothesised that oligogenicity may help to account for the intrafamilial variation in age of onset of erf and severity of clinical features .
current evidence fails to consistently identify a correlation between genotype and phenotype , therefore mutation analysis is required to identify the molecular cause . making
however , the results may be important when managing patients , to guide appropriate screening for potentially associated complications of the retina , cerebellum , liver and lungs . understanding the natural history of nphp and associated complications
will hopefully improve following completion of the current clinical trial ongoing in france , which is evaluating the evolution of nphp and related extrarenal manifestations in children ( over 7 years of age ) with a confirmed diagnosis of nphp18 ( excluding nphp7 ) ( see http://clinicaltrials.gov/ct2/show/nct01022957?term=nephronophthisis&rank=1 ) .
the results of this study may facilitate understanding in characterising genotype / phenotype associations .
although nphp - related ciliopathies are heterogenic disorders , the true frequency of oligogenicity remains uncertain .
it is however interesting that mutation analysis of 18 nphp associated ciliopathy disease genes ( including 12 nphp genes , sdccag8 was not included ) in 120 patients with nphp and related ciliopathies , using dna pooling and next generation sequencing , recently failed to identify any evidence of oligogenicity .
remarkably , in 75% of patients in this cohort , no mutations were detected in the known candidate nphp genes .
since the molecular cause of nphp remains unidentified in 7075% of cases , it is anticipated that additional nphp genes will be discovered .
whilst genes involved in the structure and function of the primary cilium are logical candidates to consider , indeed this approach has resulted in the recent successful identification of ttc21b , it is interesting that noncilial causal genes such as xpnpep3 are now being identified .
additionally , genes implicated in maintaining the cell cytoskeleton and cellular junctions are likely involved . whilst identifying causal genes is fundamental to determine the pathogenesis of nphp , it is the tip of the iceberg and we need to understand the functional consequences of such mutations within tissues .
in 2005 , realisation that polycystin-1 and polycystin-2 ( protein products of adpkd genes pc1 and pc2 ) and the discovered nephrocystins ( nphp15 ) were all expressed in the primary cilium , basal body , and centrosomes led to consideration of the term ciliopathy as a unifying theory for cystic kidney disease . a few years earlier , the concept of a ciliopathy
, a disorder in which abnormal structure or function of cilia / centrosomes is associated with defective proteins encoded by mutated genes , was attributed to the multisystem disorder bbs . in the intervening years , the primary
primary cilia are composed of an axoneme containing nine microtubular doublets which extend by a process of intraflagellar transport ( ift ) and mediate the trafficking of signals between the extra- and intracellular environments .
cilia are considered to be involved in mechanosensation of urinary flow in the renal tubules .
normally , in healthy kidneys , the renal cortical collecting duct ( ccd ) concentrates urine by responding to vasopressin , which binds to vasopressin-2 receptors ( v2r ) .
v2r are coupled to adenylyl cyclase resulting in increased intracellular cyclic amp ( camp ) , leading to phosphorylation of aquaporin-2 water channels ( aqp2 ) , which mediate water reabsorption . in nphp ,
inability to concentrate urine is the earliest clinical feature and is unresponsive to desmopressin therapy . in animal models of nphp ,
vasopressin levels are elevated and thought to contribute to cystogenesis by upregulating cell proliferation .
identification of v2r in the primary cilium of renal epithelial cells is consistent with the theory of cystic kidney diseases as ciliopathies .
this also emphasises the importance of the primary cilium in water reabsorption which has recently been eloquently investigated in patients and renal epithelial cell culture models of the related ciliopathy bbs .
understanding the pathogenesis of this urine concentration defect should help explain the success of vasopressin receptor antagonists in animal models of nphp , where they induced a reduction in camp levels and caused regression of cysts . in nphp , in response to urinary flow ,
cilia are considered to alter expression of inversin and potentially influence wnt signalling pathways and planar cell polarity [ 17 , 78 ] .
originally , observations in mouse models established the link between primary cilia and cystic kidney disease : the orpk mouse model of arpkd with a tg737 mutation ( disrupting the protein polaris ) has impaired ciliogenesis and renal cysts .
the extrarenal manifestations of nphp including retinal degeneration and sls , usually associated with nphp5 and nphp6 mutations , can be explained by ciliary dysfunction .
retinal photoreceptors contain a connecting cilium through which rhodopsin traffics along , mediating photosensation .
both nephrocystin-5 and -6 are expressed in the connecting cilia of retinal photoreceptors and disrupted structure or function of these proteins interferes with rhodopsin transport , leading to retinal degeneration ( 17 , 20 ) . through their involvement in various cellular signalling pathways including hh , calcium , and wnt ,
cilia mediate several fundamental processes including cell cycle , proliferation , differentiation , and polarity .
proposed mechanisms for renal cystogenesis include abnormal cell proliferation , fluid secretion , and disorientated cell division leading to cystic expansion rather than longitudinal tubular growth .
however , aberrations in the signalling pathways linking cilia to cystogenesis remain incompletely understood , complicated by sometimes contradictory evidence .
wnt signalling involves several ciliary proteins including pc1 , pc2 , inversin , nephrocystin-3 , jouberin , bbs1 , bbs4 , bbs6 , ofd1 , and hnf1 , to regulate cell proliferation and differentiation .
it is composed of two pathways : canonical ( -catenin dependent ) and noncanonical ( or planar cell polarity ( pcp ) ) ; the functional branch appears to be determined in part by inversin acting as a switch at the base of the primary cilium .
interestingly , both over activation [ 49 , 81 ] and underactivation of the canonical wnt pathway have been identified in animal models of nphp and js , suggesting that unbalanced canonical wnt signalling is damaging and mediates cystogenesis .
however , this theory has recently been refuted by studies in the inv mouse model of nphp , where no change in canonical wnt signalling was identified between cystic inv mutants and controls .
pcp describes the normal intrinsic organisation of cells in a tissue plane perpendicular to their apicobasal polarity .
pcp regulates kidney tubule development or recovery from injury by convergent extension and orientated cell division [ 78 , 84 ] , meaning that cells are spatially orientated and divide along an axis to maintain a constant tubule diameter whilst elongating [ 78 , 85 ] .
several mouse models of cystic kidney disease provide evidence of aberrant pcp signalling [ 83 , 86 ] .
an excellent , comprehensive review of the role of wnt signalling in cystic kidney disease has been published recently . the other signalling pathway with particular relevance to understanding the pathophysiology of nphp is the hh pathway .
an association with nphp was realised when hh effector proteins , gli transcription factors , were noted to be related to glis2 , the protein product of nphp7 .
loss of glis2 promotes epithelial to mesenchymal translation ( emt ) , fibrosis and apoptosis , and histological hallmarks of nphp .
thus although nphp7 is a rare cause of nphp , its discovery has contributed important understanding to the signalling pathways involved .
in order to establish a clinical diagnosis of nphp , a detailed history , clinical examination , including looking for extrarenal associations ( abnormal eye movements , retinopathy , ataxia , polydactyly , and cardiac malformations ) is required .
a detailed family history must be taken both to facilitate diagnosis and to highlight other individuals who should be invited for review .
appropriate investigations include renal and liver function tests ; urine concentration ability , renal and hepatic ultrasound , cerebral imaging if clinically indicated , and referral to an ophthalmologist ( figure 1 ) .
after genetic counselling , blood may be sent for genetic testing ( table 2 ) to genetic testing organisations ( e.g. , http://www.ukgtn.nhs.uk/ or http://www.eurogentest.org/ ) to seek a molecular diagnosis .
regular review is required to appropriately manage ckd / erf , and individuals with extrarenal manifestations should be referred to appropriate colleagues and are ideally best managed in specialist clinics .
clinicians must focus on optimising the delivery of renal replacement therapy , ideally with renal transplantation where possible .
however with a growing understanding of the pathophysiology of nphp , the future is more hopeful . in recent years various drugs including vasopressin receptor antagonists , mtor inhibitors ( mammalian target of rapamycin ) , triptolide and roscovitine ( cyclin - dependent kinase inhibitor ) have been shown to be effective in reducing renal cysts in animal models of nphp and adpkd .
many of these drugs are currently or have recently been involved in clinical trials in adult patients .
furthermore , large numbers of compounds which could be potential therapies are being screened in zebrafish models of ciliopathies .
understanding of the molecular genetics of nphp has advanced considerably over the last few years .
we are increasingly aware of the heterogeneity , the pleiotropic nature of mutations , and oligogenicity , all of which contribute to the complexity of nphp .
identification of further nphp genes , many of which may be ciliary , is warranted to provide further clues to its pathogenesis .
this will require international multidisciplinary collaboration to sequence patient cohorts with no current molecular diagnosis and to screen candidate genes in animal and cell models .
acknowledgement that the genetic cause is unknown in 70% of nphp cases , combined with awareness that a mitochondrial gene , xpnpep3 , has recently been identified to cause an nphp - like phenotype , may encourage us to consider other nonciliary candidates , such as genes involved in cell - cell contacts and the cytoskeleton . ultimately understanding the physiological outcomes at a protein and cellular level
Output:
| nephronophthisis ( nphp ) is an autosomal recessive cystic kidney disease and a leading genetic cause of established renal failure ( erf ) in children and young adults . early presenting symptoms in children with nphp include polyuria , nocturia , or secondary enuresis , pointing to a urinary concentrating defect .
renal ultrasound typically shows normal kidney size with increased echogenicity and corticomedullary cysts .
importantly , nphp is associated with extra renal manifestations in 1015% of patients .
the most frequent extrarenal association is retinal degeneration , leading to blindness .
increasingly , molecular genetic testing is being utilised to diagnose nphp and avoid the need for a renal biopsy . in this paper
, we discuss the latest understanding in the molecular and cellular pathogenesis of nphp .
we suggest an appropriate clinical management plan and screening programme for individuals with nphp and their families . |
PubmedSumm118659 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: systemic lupus erythematosus ( sle ) , an autoimmune disorder , is commonly associated with bacterial and viral infections .
progressive disseminated histoplasmosis in sle is a rare finding and mainly reported in adult population .
systemic lupus erythematosus ( sle ) , an autoimmune disorder , is commonly associated with bacterial and viral infections and less frequently with opportunistic fungal infections .
classical histoplasmosis , also known as darling 's disease , is a deep mycotic infection caused by one of the two thermal dimorphic fungi , histoplasma capsulatum and histoplasma duboisii .
progressive disseminated histoplasmosis ( pdh ) which commonly affects immunocompromised patients represents a severe form of the disease .
an association between sle and histoplasmosis in adult patients has been published in a recent report which revealed 8 out of 14 patients had pdh .
. therefore , we report a case of pdh in a 13-year - old girl who was diagnosed with juvenile sle ( jsle ) .
a 13-year - old girl presented with malar rash [ figure 1a ] , fever , myalgia , stiffness of hands and knees , and photosensitivity . on physical examination , she appeared febrile ( 39.5c ) , pale ( 2 + pallor ) , with heart rate 120/min , respiratory rate of 28 breaths / min , and blood pressure 112/70 mmhg .
on auscultation , she had diffuse wheezing , crepitations in lower thirds of lungs , and rhythmic heart sounds without murmurs .
laboratory examination revealed the following results : hemoglobin ( hb ) - 9.0 g / dl ; hematocrit - 27% ; white blood cell ( wbc ) count - 2800/mm ( 95% neutrophils , 2% lymphocytes , and 3% monocytes ) , platelet count - 56,000/mm ; c - reactive protein - 40 mg / l ( normal < 5.0 mg / l ) ; c3 , 35 mg / dl ( normal 90180 mg / dl ) ; c4 , 7.0 mg / dl ( 1040 mg / dl ) ; antinuclear antibodies ( anas ) by indirect immunofluorescence ( 1/640 homogenous nuclear pattern ) .
chest x - ray revealed opacification of both hemithoraces and 24 h proteinuria , 1.0 g ( normal
a diagnosis of jsle was established according to the revised classification criteria proposed by the american college of rheumatology , based on malar rash , photosensitivity , nonerosive arthritis , positive ana , serositis ( pleural effusion ) , and hematological disorder ( leukopenia , lymphopenia , and thrombocytopenia ) , and proteinuria .
she was treated with oral prednisolone ( 60 mg / day ) and hydroxychloroquine ( 150 mg / day ) .
( b ) generalized erythematous maculopapular rash , observed on follow - up seven months later , she presented with high fever , severe cough with expectoration , abdominal pain , and distension with generalized erythematous maculopapular rash [ figure 1b ] .
routine blood test revealed hb - 8.5 g / dl ; wbc - 2000/mm ; platelet count - 30,000/mm .
abdominal computed tomography ( ct ) showed evidence of hepatosplenomegaly and enlarged retroperitoneal lymph nodes with thoracic ct showing bilateral hilar lymphadenopathy .
a punch biopsy was taken from the skin lesion on the forearm , and histopathological examination of the formalin - fixed , paraffin embedded , and hematoxylin - eosin stained sections revealed diffuse infiltration of the dermis with small round to oval organisms surrounded by a clear space resembling spores of histoplasma sp . [ figure 2a and b ] .
the organisms were better appreciated in periodic acid - schiff [ figure 2c ] and methenamine silver stains .
( a ) histology of skin showing diffuse infiltration of the dermis by yeast cells of histoplasma ( h and e , 100 ) .
( b ) high - power view highlighting spores of histoplasma in the dermis ( h and e , 400 ) .
schiff positive spores of histoplasma in the dermis ( periodic acid schiff , 400 ) .
( d ) bone marrow aspiration smear showing macrophages containing histoplasma spores ( leishman 's stain , 400 ) .
( e ) bone marrow biopsy section showing yeast cells of histoplasma ( h and e , 400 ) .
( f ) periodic acid schiff positive spores of histoplasma in bone marrow ( periodic acid schiff , 400 ) bone marrow ( bm ) aspiration as well as biopsy was done which revealed hypocellular marrow with macrophages containing numerous intracytoplasmic oval organisms with a surrounding clear halo similar to those found in skin biopsy [ figure 2d f ] .
the patient was started on intravenous amphotericin b ( 1.0 mg / kg / day ) . despite this therapy
an autopsy revealed the evidence of septic shock and disseminated histoplasmosis involving lung , lymph nodes and bm with no signs of pulmonary thrombosis , and vasculitis .
we are reporting a case of jsle with fatal disseminated histoplasmosis and to the best of our knowledge , only one case with similar findings has been reported in the literature .
the disease can be broadly classified into three subtypes : acute pulmonary form ( found in immunocompetent host ) , chronic pulmonary form ( associated with anatomical defect ) , and disseminated histoplasmosis ( seen in immunocompromised individuals ) .
this mycotic infection is mostly asymptomatic and has a self - limited course in normal children .
disseminated histoplasmosis is quite rare and is seen in only 10% of patients with histoplasmosis , particularly seen in immunocompromised individuals like those receiving immunosuppressive drugs and corticosteroids after transplantation , or suffering from acquired immunodeficiency syndrome . in sle , both occurrences of localized or diffuse histoplasmosis are unusual and such association is mainly reported in adult patients .
patients with disseminated disease present with nonspecific symptoms such as fever , malaise , anorexia , weight loss , cough , and dyspnea as were noted in our patient .
features meeting the criteria of pdh in our case were persistence of clinical manifestations which did not improve even after 3 weeks of acute infection along with extrapulmonary tissue involvement as confirmed by physical , laboratory , and radiographic evaluation .
the presence of histoplasma infection was confirmed by the histopathological examination of tissue section and culture which are regarded as the gold standard methods . disseminated disease subtype mainly involves bm and lung as was observed in our case .
pulmonary hypertension was observed in our patient , the cause of which might be due to alveolar hemorrhage caused by histoplasmosis .
histoplasmosis mainly affects lupus patients on immunosuppressive drugs such as corticosteroids , cyclophosphamide , azathioprine , and rituximab as was noted in our case .
disseminated histoplasmosis is usually treated with amphotericin b and itraconazole for 3 completed months . in spite of aggressive therapy
the key factors which led to the dismal outcome of our case were delay in diagnosis of histoplasmosis and failure to administer antifungal therapy promptly .
we report a case of disseminated histoplasmosis in an active jsle patient who presented with generalized cutaneous rash , lymph nodal , lung , and bm involvement .
a high degree of clinical suspicion is needed for early diagnosis and prompt management with antifungal drugs should be advocated for favorable prognosis .
the authors certify that they have obtained all appropriate patient consent forms . in the form the patient(s )
has / have given his / her / their consent for his / her / their images and other clinical information to be reported in the journal .
the patients understand that their names and initials will not be published and due efforts will be made to conceal their identity , but anonymity can not be guaranteed .
we are reporting a case of disseminated histoplasmosis in a juvenile sle patient which is an exceedingly rare occurrence with only one case in the literature .
high level of suspicion is necessary for prompt diagnosis and treatment includes aggressive antifungal therapy .
a delay in diagnosis usually results in an ominous outcome which we encountered in our case .
the authors certify that they have obtained all appropriate patient consent forms . in the form the patient(s )
has / have given his / her / their consent for his / her / their images and other clinical information to be reported in the journal .
the patients understand that their names and initials will not be published and due efforts will be made to conceal their identity , but anonymity can not be guaranteed .
we are reporting a case of disseminated histoplasmosis in a juvenile sle patient which is an exceedingly rare occurrence with only one case in the literature .
high level of suspicion is necessary for prompt diagnosis and treatment includes aggressive antifungal therapy .
a delay in diagnosis usually results in an ominous outcome which we encountered in our case .
the authors certify that they have obtained all appropriate patient consent forms . in the form the patient(s )
has / have given his / her / their consent for his / her / their images and other clinical information to be reported in the journal .
the patients understand that their names and initials will not be published and due efforts will be made to conceal their identity , but anonymity can not be guaranteed .
we are reporting a case of disseminated histoplasmosis in a juvenile sle patient which is an exceedingly rare occurrence with only one case in the literature .
high level of suspicion is necessary for prompt diagnosis and treatment includes aggressive antifungal therapy .
a delay in diagnosis usually results in an ominous outcome which we encountered in our case .
Output:
| histoplasmosis is a systemic fungal infection caused by dimorphic fungus , histoplasma capsulatum .
immunocompetent individuals usually have self - limiting or localized disease whereas immunocompromised individuals develop disseminated disease .
the occurrence of progressive disseminated histoplasmosis in juvenile systemic lupus erythematosus is extremely rare with only one reported case in literature showing such association .
therefore , we report a case of severe opportunistic fungal infection caused by histoplasma in a 13-year - old girl who was diagnosed with juvenile lupus erythematosus , subsequently developed septic shock and died of the disease despite of aggressive antifungal therapy . |
PubmedSumm118660 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: essential genes are those indispensable for the survival of an organism under certain conditions , and the functions they encode are therefore considered a foundation of life .
essential genes of an organism constitute its minimal gene set , which is the smallest possible group of genes that would be sufficient to sustain a functioning cellular life form under the most favorable conditions ( 13 ) .
determination of the minimal gene set for an organism addresses a conceptually important question : what are the basic functions needed to sustain a life form , and therefore the minimal - gene - set concept plays a key role in the emerging field , synthetic biology ( 4 ) .
essential - gene studies are of interest for practical reasons as well . for instance ,
essential genes , because of lethality from their disruptions , are attractive targets of antibiotics ( 5 ) .
some essential genes that are conserved across species are candidates for broad - spectrum drug targets , whereas those specific for one bacterium are candidates for species - specific ones . in 2004
, we constructed deg 1.0 , a database of essential genes ( 6 ) . in the past five years , fueled by the accumulation of sequenced genomes ,
sophisticated genome - wide mutagenesis techniques ( 7 ) , and the burgeoning field of synthetic biology ( 810 ) , significant advances have been made in determining essential genes in a wide range of organisms .
this paper represents an update , deg 5.0 , a database of essential genes in both prokaryotes and eukaryotes .
in parallel to the rapid progress of the essential - gene field , deg 5.0 has significant advances over deg 1.0 by the following changes :
the number of prokaryotic essential genes has increased about 10-fold , from 543 to 5260 ( table 1 ) .
( i ) in deg 1.0 , some essential genes , e.g. those in escherichia coli , were collected from literature searches , but in deg 5.0 these records were replaced by those determined by genome - wide studies using the genetic footprinting technique ( 11 ) and systematic gene knockout experiments ( 12 ) , ( ii ) in deg 1.0 , some essential genes , e.g. those in haemophilus influenzae were determined by theoretical prediction from comparative genomics studies ( 13 ) , but in deg 5.0 these records were replaced by those determined by genome - wide studies using global transposon mutagenesis ( 14 ) and ( iii ) in 2004 , only two genome - wide studies in identifying bacterial essential genes were done , but now 12 have been finished .
table 1.contents of deg version 5.0no.kingdomorganismessential gene no.methodsaturated or near saturatedreferences1prokaryoteacinetobacter baylyi499single - gene deletionsy(23)2prokaryotebacillus subtilis271single - gene deletionsy(24)3prokaryoteescherichia coli712genetic footprinting and single - gene deletionsy(11,12)4prokaryotefrancisella novicida392transposon mutagenesisy(25)5prokaryotehaemophilus influenzae642transposon mutagenesisy(14)6prokaryotehelicobacter pylori323transposon mutagenesisy(26)7prokaryotemycobacterium tuberculosis614transposon mutagenesisy(27)8prokaryotemycoplasma genitalium381transposon mutagenesisy(18)9prokaryotemycoplasma pulmonis310transposon mutagenesisy(28)10prokaryotepseudomonas aeruginosa335transposon mutagenesisy(29)11prokaryotesalmonella typhimurium230insertional - duplication mutagenesisy(31)12prokaryotestaphylococcus aureus302antisense rnan(21,22)13prokaryotestreptococcus pneumoniae244single - gene deletions and allelic replacement mutagenesisn(19,20)14prokaryotevibrio cholerae5transposon mutagenesisn(40)15eukaryotearabidopsis thaliana777t - dna insertionn(36)16eukaryotecaenorhabditis elegans294rna interferencen(34)17eukaryotedanio rerio288insertion mutagenesisn(35)18eukaryotedrosophila melanogaster339p - element insertion mutagenesisn(33)19eukaryotehomo sapiens118literature searchn(38)20eukaryotemus musculus2114literature searchn(37)21eukaryotesaccharomyces cerevisiae878single - gene deletionsy(32)in some cases , there is a slight difference between the essential - gene number reported and that in deg .
this is mainly due to annotation changes in the latest versions of genomes such that some records could not be found , or because reported results contain identical records or are only partially published.the number of essential genes in eukaryotes has increased more than 5-fold , from 878 to 4808 , because deg 1.0 only had yeast essential genes , but deg 5.0 also has those in humans , mice , worms , fruit flies , zebrafish and the plant arabidopsis thaliana .
the number of prokaryotic essential genes has increased about 10-fold , from 543 to 5260 ( table 1 ) .
( i ) in deg 1.0 , some essential genes , e.g. those in escherichia coli , were collected from literature searches , but in deg 5.0 these records were replaced by those determined by genome - wide studies using the genetic footprinting technique ( 11 ) and systematic gene knockout experiments ( 12 ) , ( ii ) in deg 1.0 , some essential genes , e.g. those in haemophilus influenzae were determined by theoretical prediction from comparative genomics studies ( 13 ) , but in deg 5.0 these records were replaced by those determined by genome - wide studies using global transposon mutagenesis ( 14 ) and ( iii ) in 2004 , only two genome - wide studies in identifying bacterial essential genes were done , but now 12 have been finished .
table 1.contents of deg version 5.0no.kingdomorganismessential gene no.methodsaturated or near saturatedreferences1prokaryoteacinetobacter baylyi499single - gene deletionsy(23)2prokaryotebacillus subtilis271single - gene deletionsy(24)3prokaryoteescherichia coli712genetic footprinting and single - gene deletionsy(11,12)4prokaryotefrancisella novicida392transposon mutagenesisy(25)5prokaryotehaemophilus influenzae642transposon mutagenesisy(14)6prokaryotehelicobacter pylori323transposon mutagenesisy(26)7prokaryotemycobacterium tuberculosis614transposon mutagenesisy(27)8prokaryotemycoplasma genitalium381transposon mutagenesisy(18)9prokaryotemycoplasma pulmonis310transposon mutagenesisy(28)10prokaryotepseudomonas aeruginosa335transposon mutagenesisy(29)11prokaryotesalmonella typhimurium230insertional - duplication mutagenesisy(31)12prokaryotestaphylococcus aureus302antisense rnan(21,22)13prokaryotestreptococcus pneumoniae244single - gene deletions and allelic replacement mutagenesisn(19,20)14prokaryotevibrio cholerae5transposon mutagenesisn(40)15eukaryotearabidopsis thaliana777t - dna insertionn(36)16eukaryotecaenorhabditis elegans294rna interferencen(34)17eukaryotedanio rerio288insertion mutagenesisn(35)18eukaryotedrosophila melanogaster339p - element insertion mutagenesisn(33)19eukaryotehomo sapiens118literature searchn(38)20eukaryotemus musculus2114literature searchn(37)21eukaryotesaccharomyces cerevisiae878single - gene deletionsy(32)in some cases , there is a slight difference between the essential - gene number reported and that in deg .
this is mainly due to annotation changes in the latest versions of genomes such that some records could not be found , or because reported results contain identical records or are only partially published .
contents of deg version 5.0 in some cases , there is a slight difference between the essential - gene number reported and that in deg .
this is mainly due to annotation changes in the latest versions of genomes such that some records could not be found , or because reported results contain identical records or are only partially published .
the number of essential genes in eukaryotes has increased more than 5-fold , from 878 to 4808 , because deg 1.0 only had yeast essential genes , but deg 5.0 also has those in humans , mice , worms , fruit flies , zebrafish and the plant arabidopsis thaliana .
determination of a minimal gene set for cellular life was made possible by the availability of the first two completely sequenced genomes from the bacteria mycoplasma genitalium ( 15 ) and h. influenzae ( 16 ) .
an attempt to determine a minimal gene set was pioneered by koonin and coworkers by comparing these two sequenced genomes that belong to two ancient bacterial lineages , based on a notion that genes that are conserved between them are likely essential for cellular functions ( 13 ) . in 1999 , venter 's group performed the first global transposon mutagenesis in m. genitalium to experimentally address the question of what is the minimal gene set for a living organism ( 17 ) , and about 300 genes were estimated to be essential and were included in deg 1.0 . however , the concept of global transposon mutagenesis is in fact based on the identification of non - essential genes , i.e. those disrupted by transposons are identified , and those not disrupted are considered essential . therefore , to gain the proof of gene dispensability in m. genitalium , venter 's group isolated and characterized every tn4001 insertion mutants that were present in individual colonies picked from agar plates ( 18 ) .
consequently , 382 genes were demonstrated to be essential , and these genes were included in deg 5.0 by replacing those in version 1.0 .
a high - density transposon mutagenesis strategy was also applied to h. influenzae ( 14 ) , and the essential genes so obtained replaced corresponding records in deg 1.0 , which were determined by comparative genomics ( 13 ) . in deg 1.0 , essential genes of e. coli were collected from http://magpie.genome.wisc.edu/~chris/essential.html , in which essential genes were obtained by searching related literatures . using a genetic footprinting technique ,
gerdes et al . ( 11 ) conducted a genome - wide , comprehensive experimental assessment of the e. coli genes necessary for robust aerobic growth , and consequently , 620 genes were identified to be essential . in addition , the keio collection contains 303 essential genes that were determined by systematic single - gene knockout experiments ( 12 ) .
therefore , in deg 5.0 , essential gene records obtained by literature search were replaced by those obtained through both genome - wide mutagenesis studies ( 11 ) and systematic single - gene knockout experiments ( 12 ) , except that only one copy is retained for the 205 genes that overlap between the two studies .
about 100 streptococcus pneumoniae essential genes were determined by a high - throughput gene disruption system ( 19 ) .
later , 133 essential genes were determined by allelic replacement mutagenesis ( 20 ) . in deg 5.0 ,
the two results were combined by removing redundant records , resulting in 244 essential genes in s. pneumoniae .
deg 1.0 contained 65 staphylococcus aureus essential genes determined by using antisense rna technique ( 21 ) , and deg 5.0 now contains 302 s. aureus essential genes by combining with results from the studies using the rapid shotgun antisense rna method ( 22 ) . in the past several years
, many genome - wide mutagenesis studies have been performed in a wide range of bacteria .
in addition to those mentioned above , deg 5.0 contains essential genes determined by large - scale single - gene deletion studies in acinetobacter baylyi ( 23 ) and bacillus subtilis ( 24 ) , those determined by global transposon mutagenesis in francisella novicida ( 25 ) , helicobacter pylori ( 26 ) , mycobacterium tuberculosis ( 27 ) , mycoplasma pulmonis ( 28 ) and pseudomonas aeruginosa ( 29,30 ) , and those determined by trapping lethal insertions in salmonella typhimurium ( 31 ) .
another major improvement in deg 5.0 is the inclusion of essential genes of many eukaryotes , including animals and the plant a. thaliana , whereas the only eukaryotic species in deg 1.0 was saccharomyces cerevisiae ( 32 ) .
the goal of determining bacterial minimal gene set also applies to eukaryotes , i.e. to define a minimal gene set needed to produce a living multicellular organism or a viable plant .
although this goal is obviously too ambitious at the current stage , much effort has already been devoted in the identification of essential genes in eukaryotes . in the drosophila genome , about 25% of genes
were disrupted by p - element insertions by the berkeley drosophila genome project ( 33 ) , and those genes whose disruption had lethal phenotypes were collected in deg 5.0 . in the caenorhabditis
( 34 ) inhibited the activity of about 86% of all genes , and characterized their phenotypes , and genes whose inhibition were lethal were included in deg 5.0 .
hopkins and coworkers conducted a large - scale insertional mutagenesis in zebrafish to identify genes essential for embryonic and early larval development ( 35 ) , and the identified essential genes were collected in deg 5.0 .
the first large - scale identification of essential genes in a flowering plant was performed by meinke and coworker in a. thaliana by characterizing a large number of t - dna insertion lines ( 36 ) , and the identified essential genes were collected in deg 5.0 .
large - scale gene inactivation studies have not been performed in mice , likely due to technical difficulties and labor intensiveness , however , because mice are probably the most important model organism , a large number of genes have already been inactivated by individual laboratories . in a study comparing essentiality between duplicate genes and singleton genes , liao and zhang ( 37 ) analyzed nearly 3900 individually inactivated mouse genes , and found that about 55% were essential in both singletons and duplicates .
the essential genes analyzed in this study were collected in deg 5.0 . in another study comparing human and mouse essential genes , liao and zhang ( 38 ) extensively reviewed literatures to find genes whose null mutations in humans are lethal , and these human essential genes were also collected in deg 5.0 .
the whole database is divided into two subdatabases , those of prokaryotic and eukaryotic essential genes .
each entry has a unique deg identification number , gene name , gene reference number , gene function , and dna and protein sequences . for prokaryotic essential genes , a link to the cog information ( 39 )
all information is stored and operated by an open - source database management system , mysql , which allows rapid data retrieval .
users can browse the essential gene records , and can also search for essential genes by their names , functions , accession numbers and organisms .
in addition , users can also perform blast searches against deg for query dna or protein sequences .
because the database is composed of two subdatabases , i.e. those for prokaryotes and eukaryotes , users need to perform the functions of browse , search and blast in individual databases .
determination of a minimal gene set for cellular life was made possible by the availability of the first two completely sequenced genomes from the bacteria mycoplasma genitalium ( 15 ) and h. influenzae ( 16 ) .
an attempt to determine a minimal gene set was pioneered by koonin and coworkers by comparing these two sequenced genomes that belong to two ancient bacterial lineages , based on a notion that genes that are conserved between them are likely essential for cellular functions ( 13 ) . in 1999 , venter 's group performed the first global transposon mutagenesis in m. genitalium to experimentally address the question of what is the minimal gene set for a living organism ( 17 ) , and about 300 genes were estimated to be essential and were included in deg 1.0 . however , the concept of global transposon mutagenesis is in fact based on the identification of non - essential genes , i.e. those disrupted by transposons are identified , and those not disrupted are considered essential . therefore , to gain the proof of gene dispensability in m. genitalium , venter 's group isolated and characterized every tn4001 insertion mutants that were present in individual colonies picked from agar plates ( 18 ) .
consequently , 382 genes were demonstrated to be essential , and these genes were included in deg 5.0 by replacing those in version 1.0 .
a high - density transposon mutagenesis strategy was also applied to h. influenzae ( 14 ) , and the essential genes so obtained replaced corresponding records in deg 1.0 , which were determined by comparative genomics ( 13 ) . in deg 1.0 , essential genes of e. coli were collected from http://magpie.genome.wisc.edu/~chris/essential.html , in which essential genes were obtained by searching related literatures . using a genetic footprinting technique ,
gerdes et al . ( 11 ) conducted a genome - wide , comprehensive experimental assessment of the e. coli genes necessary for robust aerobic growth , and consequently , 620 genes were identified to be essential . in addition , the keio collection contains 303 essential genes that were determined by systematic single - gene knockout experiments ( 12 ) .
therefore , in deg 5.0 , essential gene records obtained by literature search were replaced by those obtained through both genome - wide mutagenesis studies ( 11 ) and systematic single - gene knockout experiments ( 12 ) , except that only one copy is retained for the 205 genes that overlap between the two studies .
about 100 streptococcus pneumoniae essential genes were determined by a high - throughput gene disruption system ( 19 ) .
later , 133 essential genes were determined by allelic replacement mutagenesis ( 20 ) . in deg 5.0 ,
the two results were combined by removing redundant records , resulting in 244 essential genes in s. pneumoniae .
deg 1.0 contained 65 staphylococcus aureus essential genes determined by using antisense rna technique ( 21 ) , and deg 5.0 now contains 302 s. aureus essential genes by combining with results from the studies using the rapid shotgun antisense rna method ( 22 ) . in the past several years
, many genome - wide mutagenesis studies have been performed in a wide range of bacteria .
in addition to those mentioned above , deg 5.0 contains essential genes determined by large - scale single - gene deletion studies in acinetobacter baylyi ( 23 ) and bacillus subtilis ( 24 ) , those determined by global transposon mutagenesis in francisella novicida ( 25 ) , helicobacter pylori ( 26 ) , mycobacterium tuberculosis ( 27 ) , mycoplasma pulmonis ( 28 ) and pseudomonas aeruginosa ( 29,30 ) , and those determined by trapping lethal insertions in salmonella typhimurium ( 31 ) .
another major improvement in deg 5.0 is the inclusion of essential genes of many eukaryotes , including animals and the plant a. thaliana , whereas the only eukaryotic species in deg 1.0 was saccharomyces cerevisiae ( 32 ) .
the goal of determining bacterial minimal gene set also applies to eukaryotes , i.e. to define a minimal gene set needed to produce a living multicellular organism or a viable plant .
although this goal is obviously too ambitious at the current stage , much effort has already been devoted in the identification of essential genes in eukaryotes . in the drosophila genome , about 25% of genes
were disrupted by p - element insertions by the berkeley drosophila genome project ( 33 ) , and those genes whose disruption had lethal phenotypes were collected in deg 5.0 . in the caenorhabditis
( 34 ) inhibited the activity of about 86% of all genes , and characterized their phenotypes , and genes whose inhibition were lethal were included in deg 5.0 .
hopkins and coworkers conducted a large - scale insertional mutagenesis in zebrafish to identify genes essential for embryonic and early larval development ( 35 ) , and the identified essential genes were collected in deg 5.0 .
the first large - scale identification of essential genes in a flowering plant was performed by meinke and coworker in a. thaliana by characterizing a large number of t - dna insertion lines ( 36 ) , and the identified essential genes were collected in deg 5.0 .
large - scale gene inactivation studies have not been performed in mice , likely due to technical difficulties and labor intensiveness , however , because mice are probably the most important model organism , a large number of genes have already been inactivated by individual laboratories . in a study comparing essentiality between duplicate genes and singleton genes , liao and zhang ( 37 ) analyzed nearly 3900 individually inactivated mouse genes , and found that about 55% were essential in both singletons and duplicates .
the essential genes analyzed in this study were collected in deg 5.0 . in another study comparing human and mouse essential genes , liao and zhang ( 38 ) extensively reviewed literatures to find genes whose null mutations in humans are lethal , and these human essential genes were also collected in deg 5.0 .
the whole database is divided into two subdatabases , those of prokaryotic and eukaryotic essential genes .
each entry has a unique deg identification number , gene name , gene reference number , gene function , and dna and protein sequences . for prokaryotic essential genes , a link to the cog information ( 39 )
all information is stored and operated by an open - source database management system , mysql , which allows rapid data retrieval .
users can browse the essential gene records , and can also search for essential genes by their names , functions , accession numbers and organisms .
in addition , users can also perform blast searches against deg for query dna or protein sequences .
because the database is composed of two subdatabases , i.e. those for prokaryotes and eukaryotes , users need to perform the functions of browse , search and blast in individual databases .
deg 5.0 has significant advances over deg 1.0 in both the number of essential genes and the number of organisms in which these genes are determined .
these updates not only represent significant advances over the 2004 version of deg , but also represent the rapid progress of the essential - gene field . in future , in prokaryotes , fueled by the availability of more and more complete genomes and the emerging field , synthetic biology , it is expected that the increase in the essential gene number will accelerate , whereas in eukaryotic model organisms , because most gene essentiality screens are far from saturated , the number of essential genes is also expected to grow .
we welcome users ' comments , corrections and new information , which will be used for updating .
the present work was supported in part by the national natural science foundation of china ( nnsf 90408028 ) . funding for open access charge : nnsf 90408028 .
Output:
| essential genes are those indispensable for the survival of an organism , and their functions are therefore considered a foundation of life .
determination of a minimal gene set needed to sustain a life form , a fundamental question in biology , plays a key role in the emerging field , synthetic biology .
five years after we constructed deg , a database of essential genes , deg 5.0 has significant advances over the 2004 version in both the number of essential genes and the number of organisms in which these genes are determined .
the number of prokaryotic essential genes in deg has increased about 10-fold , mainly owing to genome - wide gene essentiality screens performed in a wide range of bacteria .
the number of eukaryotic essential genes has increased more than 5-fold , because deg 1.0 only had yeast ones , but deg 5.0 also has those in humans , mice , worms , fruit flies , zebrafish and the plant arabidopsis thaliana .
these updates not only represent significant advances of deg , but also represent the rapid progress of the essential - gene field .
deg is freely available at the website http://tubic.tju.edu.cn/deg or http://www.essentialgene.org . |
PubmedSumm118661 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: obesity , the worldwide increasing problem , associates with several metabolic abnormalities and increases the risk of chronic diseases such as type 2 diabetes , cardiovascular diseases , and certain forms of cancer .
obesity is also the major risk factor for nonalcoholic fatty liver disease ( nafld ) , a disease spectrum that includes hepatic steatosis , steatohepatitis , fibrosis , and liver cirrhosis [ 2 , 3 ] .
the fatty liver has been shown to be insulin resistant and to overproduce glucose , vldl , crp , and coagulation factors leading to hyperglycemia and lipid disorders .
while excessive calorie intake and subsequent obesity are associated with several health problems , calorie restriction ( cr ) with adequate nutrition ameliorates obesity - induced metabolic disturbances , and it has also been proven to be an effective treatment for nafld [ 5 , 6 ] . in rodents , cr extends lifespan by up to 50% .
the mechanisms underlying the beneficial effects of cr is not well understood ; however , accumulating evidence indicates an important role for sirtuins , a highly conserved family of nad - dependent enzymes regulating lifespan in lower organisms , as metabolic sensors and mediators of the cellular effects of cr . at present , seven sirtuins ( sirt1sirt7 ) have been discovered from mammals , and of them nuclear located sirt1 is the closest homologue of sir2 protein that regulates the aging processes and mediates the cr - induced extension of lifespan in lower organisms [ 9 , 10 ] .
sirt1 has been shown to increase cellular stress resistance and genomic stability , and it regulates cellular senescence and energy metabolism via deacetylation of the target proteins such as p53 , foxo transcription factors , and pgc-1 [ 10 , 11 ] .
it has been claimed that the beneficial cellular effects of cr are largely mediated by induction of sirt1 whereas considerably less is known about the other members of sirtuin family .
interestingly , crosstalk has been shown between mitochondrial and nuclear sirtuins , and sirt4 has been shown to regulate fatty acid oxidation in hepatocytes through sirt1-dependent manner .
in addition , sirt3 regulates mitochondrial function , thermogenesis , and mitochondrial fatty acid oxidation by promoting expression of mitochondrial genes , and by regulating the acetylation levels of metabolic enzymes , including acetyl coenzyme a synthetase 2 ( acecs2 ) [ 15 , 16 ] , and long - chain acyl coenzyme a dehydrogenase ( lcad ) .
moreover , sirt3 regulates atp synthesis by deacetylating several proteins in mitochondria electron transport complex i .
sirt3 is the only sirtuin with a reported association with the human lifespan [ 19 , 20 ] , making it an interesting novel target for energy homeostasis . as weight loss and
subsequent body weight maintenance has been shown to be very difficult for obese individuals and as the compliance for low - calorie diets is often very poor in long - term clinical trials , several sirtuin - activating compounds ( stacs ) mimicking the beneficial effects related to cr have been developed recently .
resveratrol ( 3,5,4-trihydroxystillbene ) , a natural polyphenolic compound derived from the grapes , was one of the first stacs that was shown to extend yeast lifespan through an sirt1-dependent mechanism .
more recently , the beneficial effects of resveratrol were reported in mammalian cells . in vivo studies with experimental obesity models have revealed that resveratrol improves health and prevents premature mortality associated with obesity [ 23 , 24 ] .
it is generally believed that resveratrol is mimicking the beneficial effects of cr mainly in an sirt1-dependent manner .
the aim of the present study was to investigate the potential of long - term resveratrol supplementation to mimic the beneficial effects of cr without reducing calorie intake .
we compared the effects of cr and resveratrol on diet - induced obesity and fatty liver formation .
we also examined the effects of cr and resveratrol on metabolic performance , adipocyte inflammatory response , and tissue - specific protein expressions of sirt1 and mitochondrial sirtuins sirt3 and sirt4 .
lean mice receiving a standard low - fat diet served as healthy controls , and data from these animals were used as reference values in the present study .
seven - week - old male c57bl/6j ( charles river , germany ) mice were housed three , four , or five mice in a cage in a standard experimental laboratory , illuminated from 07.00 to 19.00 , at temperature 22 1c .
the protocols were approved by the animal experimentation committee of the university of helsinki ( number 0706589 ) , finland , and the principles of laboratory animal care ( nih publication no .
after a one - week acclimatization period the mice ( initial body weight 21.3 0.1 g ) were divided to five groups for 15 weeks : ( 1 ) hfd group ( n = 18 ) received high - fat diet ( 60% of energy from fat , d12492 , research diet inc . ;
usa ) ad libitum , ( 2 ) cr group ( n = 18 ) received hfd and was kept under calorie restriction ( energy intake 70% of ad libitum intake ) , ( 3 ) hfd + r2 group ( n = 19 ) received hfd mixed with low - dose resveratrol ( 2 g / food kg ; orchid chemicals & pharmaceuticals ltd . ,
india ) , ( 4 ) hfd + r4 group ( n = 19 ) received hfd mixed with high - dose resveratrol ( 4 g / kg food ) , ( 5 ) lfd group ( n = 18 ) received low - fat diet ( 10% of energy from fat , d12450b , research diet inc .
the powered high - fat diet was moistened with tap water 100 ml / kg and low - fat diet with tap water 200 ml / kg , packed in one - day portions and stored at 20c .
the food consumption was monitored daily and the body weight three times per week by using a standard table scale ( mettler - toledo , columbus , usa ) .
the body fat percentage was analyzed from anesthetized mice by magnetic resonance imaging ( mri ; oxford instrument , oxford , uk ) .
the effects of resveratrol and cr on metabolic performance , physical activity , drinking , and feeding behaviour were analysed by housing six mice from each group in a home cage - based monitoring system for laboratory animals ( labmaster tse system , bad homburg , germany ) .
labmaster system combines various sensors that monitor simultaneously , noninvasively , and continuously both in light and dark phases several physiological and behavioural parameters for each animal . during the experiment mice
the measuring time was 100 hours consisting of 52 hours light phase and 48 hours dark phase .
the drinking and feeding behaviour of the mice was measured by high - precision sensors attached to the top of the cage lids .
the indirect calorimetry system is an open - circuit measuring system , which allowed determination of mice o2 consumption , co2 production , respiratory exchange rate , and heat production .
the infrared light - beams sensors surrounding the cage detected mice physical activity comprising ambulatory , fine , and rearing movements . at the end of the calorimetric measurements the mice were decapitated .
liver , muscle ( musculus quadriceps femoris ) , and subcutanic , epididymal , abdominal , and perirenal fat samples were dissected , washed with saline , blotted dry , and weighted .
formalin - fixed , paraffin - embedded liver sections ( 4 m ) were stained with h&e .
the stained sections were evaluated by a pathologist ( p. finckenberg ) under a conventional light microscope in a blinded fashion .
the samples were subjected to a semiquantitative histological analysis using the nonalcoholic steatohepatitis ( nash ) clinical research network scoring system for nafld with slight modifications for mice samples .
total rna was isolated by trizol reagent ( invitrogen , carlsbad , ca , usa ) .
the concentration and integrity of rna samples were analyzed by spectrophotometer ( absorbance 260 and 280 nm ) .
rna samples were treated with dnase i ( deoxyribonuclease 1 , sigma chemicals , st .
louis , mo ) and 1 g of total rna was reverse transcribed to cdna by improm - ii reverse transcription system ( promega , madison , usa ) .
the mrna expression analysis was performed using light - cycler quantitative rt - pcr instrument ( roche diagnostics , neuilly - sur - seine , france ) .
the samples were amplified with faststart dna master sybr green 1 ( roche diagnostics ) in the presence of 0.5 m of the following primers : adiponectin forward gtatcgctcagcgttc and reverse gtcgttgacgttatctgc ; cd68 forward cccgagtacagtctacc and reserve gttgattgtcgtctgcg ; leptin forward agaccgggcaagagtg and reverse gccatagtgcaaggtt ; mcp-1 ( monocyte chemoattractant protein 1 ) forward cggaaccaaatgagatcag and reverse tcacagtccgagtcac ; pai-1 ( plasminogen activator inhibitor 1 ) forward acagcctttgtcatctcagcc and reverse ccgaaccacaaagagaaagga ; visfatin forward agagtgctactggcttacc and reverse ctttcccccacgctgt and 18s forward acatccaaggaaggcagcag and reverse ttttcgtcactacctccccg .
the quantities of the pcr products were quantified with an external standard curve amplified from purified pcr product .
proteins from perirenal fat samples were isolated with cell extraction buffer ( invitrogen , carlsbad , ca , usa ) and complete protease inhibitors ( roche diagnostics , neuilly - sur - seine , france ) . proteins from liver and muscle samples were isolated with lysis buffer ( nacl 136 mm , na2hpo4 8 mm , kcl 2.7 mm , kh2po4 1.46 mm , tween 20 0.001% and complete protease inhibitors ( roche diagnostics ) ) . in immunoblotting 20 g of total protein were used and protein were separated by 8% sodium dodecyl sulphate - polyacrylamide gel electrophoresis .
proteins were transferred to a polyvinyldifluoride membrane ( immobilon - fl , millipore , bedford , ma , usa ) and blocked for 2 h in 5% non - fat milk - tbs-0.05% tween 20 buffer .
the membranes were probed with anti - sir2 ( upstate , lake placid , n.y . ,
usa ) at dilution 1 : 1500 , anti - sirt3 ( abcam , cambridge , uk ) at dilution 1 : 500 and anti - sirt4 ( abcam ) at dilution 1 : 1000 in blocking buffer .
alpha - tubulin ( abcam ) at dilution 1 : 2000 was used as a loading control .
horse - radish peroxidase - conjugated anti - rabbit secondary antibody ( chemicon , temecula , ca , usa ) was used at dilution 1 : 5000 .
the localization of horse - radish peroxidase was detected with amersham ecl plus ( ge healthcare , little chalfont , uk ) according to instructions of manufacturer and visualized by fla-9000 fluorescent image analyzer ( fujifilm corp . ,
statistically significant differences in mean values were tested by one - way anova followed by the student - newman - keuls test .
analyses in a function of time were done by two - way anova followed by the bonferroni test .
body weight in mice fed with hfd increased steadily during the whole follow - up period ( figure 1(a ) ) . neither low - dose nor high - dose resveratrol influenced body - weight gain in mice fed with hfd .
the body weight in mice fed with lfd increased in parallel with hfd during the first 40 days , but thereafter remained markedly lower compared to hfd groups .
there was only a modest increase in body weight in mice kept under cr , the final body weight being markedly lower compared with all other treatment groups .
the body fat percentage measured by mri was markedly higher in mice fed with hfd compared to lfd group ( figure 1(b ) ) .
in contrast , cr decreased body fat percentage to level found in lfd - treated mice .
neither resveratrol dosages decreased fat pad weights in mice fed with hfd whereas the weight of fat pads in lfd and cr groups were significantly lower ( table 1 ) .
the weight of different fat pads in cr group was lower compared to lfd except in abdominal fat .
the food intake in mice fed with lfd was greater compared with other treatment groups ( table 2 ) . however , there was no difference in energy intake between lfd and hfd groups fed ad libitum ( table 2 ) .
the food and energy intakes in mice under cr were approximately 70% of the ad libitum control values .
the water intake in mice fed with lfd was higher compared with the other treatment groups ( table 2 ) .
interestingly both low - dose resveratrol and high - dose resveratrol treatments decreased water intake whereas cr did not influence water intake . the cumulative respiratory exchange ratio ( rer ) and co2 production in mice fed lfd was higher compared to other groups ( figures 2(a ) and 2(b ) ) .
the cumulative o2 and heat production did not differ between the study groups ( data not shown ) .
the cumulative ambulatory movements , total activity , and cumulative rearing were increased in mice kept under cr ( figures 2(c)2(e ) ) .
the cumulative fine movements did not differ between study groups ( data not shown ) .
resveratrol treatments tended to decrease total activity and cumulative rearing ; however , the difference did not reach statistical significance ( figures 2(d ) and 2(e ) ) .
the liver histology in mice fed with hfd showed prominent steatosis ( table 3 ) .
furthermore , hepatocyte ballooning indicating activity of hepatocyte degeneration was found in mice fed with hfd ( table 3 ) .
complete absence of steatosis and hepatocyte ballooning was seen in the cr and the lfd groups .
resveratrol , when given at higher dosage , tended to ameliorate steatosis and hepatocyte ballooning .
cr increased adipose tissue adiponectin mrna expression and effectively decreased the mrna expressions of inflammatory markers cd68 , leptin mcp-1 , and pai-1 in the adipose tissue ( figures 3(a)3(e ) ) .
in addition , mice fed with lfd showed lower mrna expression of cd68 , leptin , and mcp-1 ( figures 3(b)3(d ) ) .
neither low - dose resveratrol nor high - dose resveratrol influenced the mrna expressions of adipose tissue inflammatory markers ( figures 3(a)3(e ) ) .
there was no difference between hfd and lfd groups in the mrna expressions of visfatin in liver ( figure 3(f ) ) .
cr markedly upregulated the visfatin mrna expression but neither the low- or high - dose of resveratrol did not influence visfatin mrna expression ( figure 3(f ) ) .
there were no statistical significant differences between study groups in biogenesis markers pgc-1 , nrf-1 , and tfam mrna expressions in liver ( data not shown )
. mice fed with hfd showed decreased sirt1 expression in the liver as compared with lfd whereas no difference was found in skeletal muscle or adipose tissue sirt1 expression ( figures 4(a)4(c ) ) .
there was no difference between hfd and lfd groups in sirt3 protein expression in liver , skeletal muscle , and adipose tissue ( figures 4(d)4(f ) ) .
adipose tissue sirt4 protein expression was undetectable and no difference was seen between lfd and hfd group in sirt4 protein expression in liver and skeletal muscle ( figures 4(g ) and 4(h ) ) .
cr increased sirt1 expression in the liver and skeletal muscle ( figures 4(a ) and 4(b ) ) and sirt3 protein expression in liver , skeletal muscle , and adipose tissue ( figures 4(d)4(f ) ) .
in addition , cr increased sirt4 protein expression in skeletal muscle ( figure 4(h ) ) .
high - dose resveratrol increased sirt1 expression in the skeletal muscle ( figures 4(b ) ) and tended to increase liver sirt1 expression ( figure 4(a ) ) .
furthermore , high - dose resveratrol increased sirt4 protein expression in skeletal muscle and tended to increase liver sirt1 expression ( figure 4(h ) ) . neither resveratrol dosages influenced sirt3 expression ( figures 4(d)4(f ) )
we compared the effects of calorie restriction ( cr ) and resveratrol supplementation on diet - induced obesity and fatty liver formation by using c57bl/6j mice fed with high - fat diet as model of experimental obesity .
the important finding of the present study was that neither low - dose nor high - dose resveratrol treatment influenced energy intake , body weight gain , body fat percentage , or metabolic performance .
a modest protection against hepatic steatosis and hepatocyte ballooning was found by high - dose resveratrol treatment .
in contrast , cr completely prevented development of obesity and fatty liver formation as well as adipocyte tissue inflammatory response indicating superior protection as compared to resveratrol .
resveratrol has been widely used to mimic the physiological effects of cr and to counteract the noncompliance for low - calorie diets often observed in clinical trials .
recent studies have demonstrated that cr induces sirt1 [ 28 , 29 ] a key regulator of cellular metabolism whereas resveratrol activates sirt1 enzyme through binding to the active site of sirt1 enzyme . in the present study the resveratrol dosage and route of administration ( 2 or 4 g / kg food )
was based on previous study by lagouge and coworkers demonstrating improvement of mitochondrial function and protection against metabolic disease in experimental obesity .
based on our calorimetric measurements and food intake recordings the above - mentioned resveratrol diet concentrations provided 135 mg / kg and 282 mg / kg daily resveratrol dosages , respectively .
surprisingly , we were unable to confirm any statistically significant reduction in body weight or adiposity in our 15-week follow - up study although a modest trend toward slightly lower body weight was noticed both in mice fed with low - dose and high - dose resveratrol
. we can not exclude the possibility that higher resveratrol dosage or longer treatment period is needed for preventing weight gain .
even though resveratrol has been shown to produce a modest decrease in body weight also in rats fed a high - fat diet , several studies have been unable to confirm the beneficial effects of resveratrol on body weight and obesity [ 23 , 31 ] .
baur et al . showed recently that low - dosage resveratrol treatment ( about 20 mg / kg ) increases survival of high - fat - fed mice without reducing body weight .
nonalcoholic fatty liver disease ( nafld ) represents a wide variety of diseases ranging from hepatocellular steatosis through steatohepatitis to fibrosis and irreversible cirrhosis .
both nafld as well as chronic subinflammatory state caused by the release of adipokines from white adipose tissue are strongly associated with obesity , type 2 diabetes , and development of cardiovascular diseases [ 3 , 32 ] .
with assessment of obesity - induced fatty liver formation , we relied on previously published and validated histological scoring system [ 33 , 34 ] comprising histological features of which four are evaluated semiquantitatively , namely , steatosis , lobular inflammation , hepatocellular ballooning , and fibrosis . in the present study ,
the steatotic change was most commonly observed in the acinar zones 2 and 3 , thus resembling the adult human pattern .
fibrosis and inflammation are common features in human forms of nafld ; however , in diet - induced obese mice they were practically absent .
although the aforementioned scoring system is developed to detect nafld in clinical trials , we believe it is also suitable for screening fatty liver formation in experimental obesity .
we here report that cr almost completely prevented fatty liver formation whereas resveratrol produced only a modest protection against hepatic steatosis and hepatocyte ballooning .
these findings indicate superior protection against obesity - induced fatty liver formation by cr compared to resveratrol .
chronic inflammation in the adipose tissue plays an important role in the development of obesity - related insulin resistance [ 3537 ] . in the present study we demonstrated
that cr decreased mcp-1 , cd68 , leptin , and pai-1 mrna expressions in the adipose tissue as compared to obese mice fed ad libitum .
neither low - dose nor high - dose resveratrol treatment influenced inflammatory response in the adipose tissue .
in agreement with previous studies [ 3840 ] , we here report that cr induced physical activity .
sirt1 is suggested to be required for increased physical activity of cr mice , as sirt1 knock - out mice do not respond to cr with increased physical activity .
consistently , we noticed marked increases in skeletal muscle and liver sirt1 expression in mice kept under cr . even thought the higher dose of resveratrol induced sirt1 protein in skeletal muscle , resveratrol was unable to induce physical activity , and it tended to even decrease physical activity .
this is in line with previous study by lagouge et al . demonstrating that resveratrol decreases ambulatory locomotor activity and number of rears even thought improvement in neuromuscular function was detected .
nevertheless , the reason for the lower physical activity is unclear and needs further studies . cr induced sirt3 protein expression in liver , skeletal muscle , and adipose tissue suggesting that the metabolic benefits of cr are regulated also via a sirt3-dependent manner .
both sirt1 and sirt3 are nad - dependent deacetylases , and the changes in nad concentration can regulate their activity .
overexpression of visfatin ( also called nampt ) , which catalyze first and the rate - limiting step in nad biosynthesis from nam , can markedly induce sirt1 and sirt3 activity [ 42 , 43 ] .
we showed higher expression of visfatin in the cr group in liver which can also explain the higher sirt1 and sirt3 protein expression in liver .
the inability of resveratrol to induce both visfatin and sirt3 in metabolically important tissues can explain , at least in part , the ineffectiveness of resveratrol to mimic cr mediated health benefits .
interestingly , high - dose resveratrol treatment and to a lesser extent cr increased sirt4 protein expression in the skeletal muscle .
it has been shown that sirt4 is localized to mitochondria and mediates adp - ribosylation of protein substrates .
depletion of sirt4 increases insulin secretion by modulation of glutamate dehydrogenase activity in pancreatic -cells .
in addition , a recent study has provided evidence that sirt4 depletion improves fatty acid oxidation in hepatocytes in a sirt1-dependent manner .
even thought in muscle cells sirt4 depletion has been shown to improve mitochondrial function , the role of sirt4 in skeletal muscle metabolism is still unknown and needs further studies .
using diet - induced obese mice as model of experimental obesity we demonstrated superior protection against diet - induced obesity and fatty liver formation by cr as compared to oral resveratrol supplementation .
the present study also supports the notion that the beneficial metabolic effects of cr are mediated , at least in part , via sirt3-dependent pathways .
Output:
| the potential of resveratrol to mimic beneficial effects of calorie restriction ( cr ) was investigated .
we compared the effects of both cr ( 70% of ad libitum energy intake ) or resveratrol ( 2 g / kg or 4 g / kg food ) on high - fat diet - induced obesity and fatty liver formation in c57bl/6j mice , and we examined their effects on calorimetry , metabolic performance , and the expressions of inflammatory genes and sirt proteins .
we found that resveratrol with 4 g / kg dose partially prevented hepatic steatosis and hepatocyte ballooning and induced skeletal muscle sirt1 and sirt4 expression while other examined parameter were unaffected by resveratrol .
in contrast , cr provided superior protection against diet - induced obesity and fatty liver formation as compared to resveratrol , and the effects were associated with increased physical activity and ameliorated adipose tissue inflammation .
cr increased expressions of sirt3 in metabolically important tissues , suggesting that the beneficial effects of cr are mediated , at least in part , via sirt3-dependent pathways . |
PubmedSumm118662 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: nephronophthisis ( nph ) and medullary cystic kidney disease ( mckd ) are renal diseases associated with bilateral medullary polycysts and interstitial fibrosis .
these two diseases are thought to represent the same disease process according to similar clinical and pathological features , excluding the age of onset and associated genetic mutations .
the concept of juvenile nephronophthisis - medullary cystic disease complex ( nph - mckd ) has been proposed ( 1 ) . with the progression of tubular damage , tubular functions , such as sodium reabsorption and urine concentration , become impaired .
inflammation and fibrosis occurs in the tubulointerstitial area of the kidneys , ultimately leading to end - stage kidney disease ( eskd ) .
the progression to eskd is typically gradual , similar to that observed in polycystic kidney disease .
nph is an autosomal recessive ( ar ) disease that manifests in early childhood or adolescence and progresses to eskd in early adolescence .
mckd is an autosomal dominant ( ad ) disease that develops in adulthood and slowly progresses to eskd , characterized by multiple cysts , measuring 1 - 20 mm , in the corticomedullary boundary .
the clinical features of mckd are nonspecific and include hypertension , polyuria , and sodium wasting due to an impairment in urinary concentration ( 2 ) .
the pathological features include expanded urinary ducts in the corticomedullary boundary areas , diffuse tubulointerstitial nephritis with tubular atrophy , interstitial fibrosis , and an inflammatory cell infiltrate ( 3 ) .
we herein report two cases of mckd in elderly patients with enlarged kidneys and a rapid progression to eskd .
both patients had no apparent genetic history of kidney disease , and their clinical courses were not typical for traditional hereditary mckd .
an 84-year - old woman had a 3-year history of hypertension , a femoral neck fracture 1 year previously , and a left radial fracture 1 month previously .
she was noted to have renal dysfunction of unknown etiology 1 year prior to admission .
she visited a regional clinic for edema and was observed to have renal dysfunction [ serum creatinine ( cr ) , 2.7 mg / dl ] and anemia 2 months prior to admission . since that time ,
she had developed marked edema and progressive renal dysfunction ( serum cr , 3.7 mg / dl ) and was referred to our hospital for further evaluation and treatment . on physical examination ,
she showed marked abdominal distention due to ascites and also had lower extremity edema without dyspnea .
chest radiography revealed cardiac enlargement and bilateral pleural effusions , and an abdominal computed tomography ( ct ) scan revealed massive ascites and bilateral kidney enlargement ( fig .
the following laboratory results were obtained : white blood cell ( wbc ) count , 5,400 wbc / mm ; red blood cells ( rbc ) count , 25010 rbc / mm ; hemoglobin ( hb ) , 8.2 g / dl ; hematocrit ( ht ) , 24.0% ; platelet count ( plt ) , 15.810 plt / mm ; total protein ( tp ) , 5.6 g / dl ; albumin ( alb ) , 2.8 g / dl ; blood urea nitrogen ( bun ) , 45 mg / dl ; serum cr ; 3.9 mg / dl ; sodium ( na ) , 140 meq / l ; potassium ( k ) , 3.2 meq / l ; chloride ( cl ) , 104 meq / l ; c - reactive protein ( crp ) , 0.5 mg / dl ; plasma glucose , 142 mg / dl ; hemoglobin a1c ( hba1c ) , 4.8% ; aspartate aminotransferase ( ast ) , 38 iu / l ; alanine aminotransferase ( alt ) , 18 iu / l ; alkaline phosphatase ( alp ) , 787 iu / l ; gamma glutamyl transpeptidase ( gt ) , 239 iu / l ; igg , 828 mg / dl ; igm , 700 mg / dl ; and iga , 148 mg / dl .
cryoglobulin was negative and an immunoglobulin ( ig ) m ( kappa ) spike was identified on immunoelectrophoresis .
the third complement component ( c3 ) level was 59 mg / dl ( normal 50 - 130 mg / dl ) ; the fourth component ( c4 ) level was 10.5 mg / dl ( normal 10 - 50 mg / dl ) ; hemolytic complement activity via the classical pathway ( ch50 ) was 13 u / ml ( normal 25.0 - 48.0 u / ml ) ; and antinuclear antibody ( ana ) was negative .
myeloperoxidase antibodies ( mpo ) , proteinase 3 antibodies ( pr3 ) , antineutrophil cytoplasmic antibodies ( anca ) , and anti - glomerular basement membrane ( anti - gbm ) antibodies were not detected .
a urinalysis showed 1.17 g protein / g creatinine and 30 - 49 rbc / high - power field ( hpf ) .
a bone marrow aspirate clot showed hypercellular bone marrow with 3% plasma cells . computed tomography of the abdomen in case 1 .
computed tomography of the abdomen shows massive ascites and enlarged kidneys with no evidence of cysts . at the time of hospitalization , a percutaneous kidney biopsy was not performed because of the patient 's massive ascites .
a percutaneous kidney biopsy was performed 1 month later after several paracentesis procedures , allowing the patient to lie in a prone position .
histological findings revealed tubular dilatation , primarily involving the distal tubules , with extensive fibrosis in the interstitium , consistent with nephronophthisis - medullary cystic disease complex(nph - mckd ) .
there were no remarkable glomerular changes except for global sclerosis consistent with the patient 's age ( fig .
immune deposits of igg , iga , igm , c1q , c3 , and fibrinogen were absent , despite the igm kappa m protein detected in the serum .
electron microscopy revealed irregularities , thinning and disintegration of the tubular basement membrane ( tbm ) . however , it was difficult to explain the patient 's massive ascites and rapidly progressive renal dysfunction according to the histological findings .
( a ) periodic acid - schiff ( pas ) stain ; magnification 10 ; ( b ) pas stain ; 200. light microscopy images show tubular dilatation and atrophy .
the glomeruli show global sclerosis and arterial intimal thickening , consistent with the patient 's age , without any other remarkable changes such as crescent formation . considering her advanced age ( 84 years of age ) and symptomatic relief after paracentesis ,
no further investigation was done and she was discharged with a serum cr level of 5.1 mg / dl 2 months after admission .
a 74-year - old woman was started on antihypertensive therapy 1 year prior to admission when she was noted to have a mild renal impairment with a serum cr level of 1.1 mg / dl .
she was status post - appendectomy at 20 years of age , had a history of ulcerative colitis with rectal cancer at 61 years of age , and a cataract at 68 years of age .
although her blood pressure was well controlled , her serum cr level rapidly increased to 1.5 mg / dl at 3 months after the start of antihypertensive therapy and 2.4 mg / dl at 5 months after the start of therapy .
on physical examination , her temperature was 36.5 , and her blood pressure was 150/79 mmhg .
the following laboratory results were obtained : wbc count , 6,800 wbc / mm ; rbc count , 24810 rbc / mm ; hb , 7.3 g / dl ; ht , 21.7% ; plt , 18.210/mm ; tp , 7.1 g / dl ; alb , 4.1 g / dl ; bun , 30 mg / dl ; cr , 3.6 mg / dl ; na , 138 meq / l ; k , 5.3 meq / l ; cl , 107 meq / l ; crp , 0.21 mg / dl ; plasma glucose , 107 mg / dl ; hba1c , 5.1% ; igg , 1,326 mg / dl ; igm , 76 mg / dl ; iga , 239 mg / dl ; c3 , 91 mg / dl ; c4 , 24.7 mg / dl ; and ch50 , 13 u / ml .
ana was negative , and mpo , pr3 , anca , and anti - gbm were not detected .
abdominal ct showed bilateral kidney enlargement that was not seen on an earlier ct exam 1 year previously .
4 . mri , including coronal magnetic resonance images , did not reveal multiple microcysts in the enlarged kidneys , however , a careful observation revealed multiple cysts along the corticomedullary boundary .
serial changes of abdominal computed tomography ( ct ) at ( a ) 2 years prior to admission , ( b ) 1 year prior to admission and ( c ) at admission in case 2 .
there is no evidence of kidney enlargement at 2 or 1 year prior to admission ; however , ct at admission shows kidney enlargement compared with the previous ct scans . magnetic resonance imaging ( mri ) of the abdomen : ( a ) axial section of the abdomen ( t1-weighted image ) and ( b ) coronal section of the abdomen ( t2-weighted image ) in case 2 .
no apparent microcysts are seen in the enlarged kidneys , including the coronal images , however , a closer observation shows multiple cysts along the corticomedullary boundary in the left kidney in the coronal section ( arrows ) ( b ) .
of seven glomeruli , two were globally sclerotic , one was segmentally sclerotic , and two showed glomerular cysts .
the distal tubules were also dilated , consistent with mckd , and there was mild interstitial fibrosis and inflammatory cell infiltration ( fig .
electron microscopy revealed irregular layering , spheroidizing , thinning , and partial rupture of the tbm .
the patient was treated with corticosteroids [ prednisolone ( psl ) 30 mg / day ] in view of the significantly elevated urinary -2 mg level and interstitial cell infiltration . immediately after psl administration , a slight reduction in the serum cr level was noted and her anemia improved .
however , the serum cr level gradually increased and the hb level gradually decreased 2 months later , when psl was tapered .
three months after the start of psl therapy , the patient developed gastrointestinal bleeding and was found to have a serum cr level of 7 mg / dl .
however , no apparent bleeding source was detected by gastroscopy , colonoscopy , or enteroscopy .
anemia was corrected with blood transfusions , however , the patient 's renal function did not improve and she began hemodialysis therapy 5 months after referral .
( a ) periodic acid - methenamine - silver ( pam ) stain ; original magnification 10 , ( b ) pas stain original magnification 200. light microscopy images show tubular dilatation and atrophy .
cystic tubules show irregularities and thinning of the tubular epithelial cells . of seven glomeruli , two
we also performed immunohistochemical staining in both cases for cd10 , cytokeratin 7 ( ck7 ) , epithelial membrane antigen ( ema ) , e - cadherin , and cytokeratin ( 34 beta e12 ) to identify the level of tubular dilatation ( fig .
6 ) . in case 1 , the dilated tubules were negative for cd10 , a marker of proximal tubules ( 6 ) .
in contrast , immunostaining results for ck7 , ema , and e - cadherin , markers of the distal tubules and collecting ducts , were positive .
immunostaining results for ck ( 34 beta e12 ) , a marker of collecting ducts , were also positive ( 7 ) , indicating that the cysts predominantly arose from collecting ducts in case 1 . in case 2 ,
the dilated tubules were positive for ck7 and ema and weakly positive for e - cadherin and ck ( 34 beta e12 ) .
immunohistochemical staining for cd10 , cytokeratin 7 ( ck7 ) , epithelial membrane antigen ( ema ) , e - cadherin , and cytokeratin ( 34 beta e12 ) in the interstitium of both cases .
original magnification 10. the tubular basement membrane ( tbm ) of dilated tubules in both cases is negative for cd10 . in case 1 ,
the tbm of dilated tubules is positive for ck7 , ema , e - cadherin , and ck ( 34 beta e12 ) . in case 2 ,
the tmb of dilated tubules is positive for ck7 and ema and weakly positive for e - cadherin and ck ( 34 beta e12 ) .
an 84-year - old woman had a 3-year history of hypertension , a femoral neck fracture 1 year previously , and a left radial fracture 1 month previously .
she was noted to have renal dysfunction of unknown etiology 1 year prior to admission .
she visited a regional clinic for edema and was observed to have renal dysfunction [ serum creatinine ( cr ) , 2.7 mg / dl ] and anemia 2 months prior to admission . since that time ,
she had developed marked edema and progressive renal dysfunction ( serum cr , 3.7 mg / dl ) and was referred to our hospital for further evaluation and treatment . on physical examination ,
she showed marked abdominal distention due to ascites and also had lower extremity edema without dyspnea .
chest radiography revealed cardiac enlargement and bilateral pleural effusions , and an abdominal computed tomography ( ct ) scan revealed massive ascites and bilateral kidney enlargement ( fig .
the following laboratory results were obtained : white blood cell ( wbc ) count , 5,400 wbc / mm ; red blood cells ( rbc ) count , 25010 rbc / mm ; hemoglobin ( hb ) , 8.2 g / dl ; hematocrit ( ht ) , 24.0% ; platelet count ( plt ) , 15.810 plt / mm ; total protein ( tp ) , 5.6 g / dl ; albumin ( alb ) , 2.8 g / dl ; blood urea nitrogen ( bun ) , 45 mg / dl ; serum cr ; 3.9 mg / dl ; sodium ( na ) , 140 meq / l ; potassium ( k ) , 3.2 meq / l ; chloride ( cl ) , 104 meq / l ; c - reactive protein ( crp ) , 0.5 mg / dl ; plasma glucose , 142 mg / dl ; hemoglobin a1c ( hba1c ) , 4.8% ; aspartate aminotransferase ( ast ) , 38 iu / l ; alanine aminotransferase ( alt ) , 18 iu / l ; alkaline phosphatase ( alp ) , 787 iu / l ; gamma glutamyl transpeptidase ( gt ) , 239 iu / l ; igg , 828 mg / dl ; igm , 700 mg / dl ; and iga , 148 mg / dl .
cryoglobulin was negative and an immunoglobulin ( ig ) m ( kappa ) spike was identified on immunoelectrophoresis .
the third complement component ( c3 ) level was 59 mg / dl ( normal 50 - 130 mg / dl ) ; the fourth component ( c4 ) level was 10.5 mg / dl ( normal 10 - 50 mg / dl ) ; hemolytic complement activity via the classical pathway ( ch50 ) was 13 u / ml ( normal 25.0 - 48.0 u / ml ) ; and antinuclear antibody ( ana ) was negative .
myeloperoxidase antibodies ( mpo ) , proteinase 3 antibodies ( pr3 ) , antineutrophil cytoplasmic antibodies ( anca ) , and anti - glomerular basement membrane ( anti - gbm ) antibodies were not detected .
a urinalysis showed 1.17 g protein / g creatinine and 30 - 49 rbc / high - power field ( hpf ) .
a bone marrow aspirate clot showed hypercellular bone marrow with 3% plasma cells . computed tomography of the abdomen in case 1 .
computed tomography of the abdomen shows massive ascites and enlarged kidneys with no evidence of cysts . at the time of hospitalization , a percutaneous kidney biopsy was not performed because of the patient 's massive ascites .
a percutaneous kidney biopsy was performed 1 month later after several paracentesis procedures , allowing the patient to lie in a prone position .
histological findings revealed tubular dilatation , primarily involving the distal tubules , with extensive fibrosis in the interstitium , consistent with nephronophthisis - medullary cystic disease complex(nph - mckd ) .
there were no remarkable glomerular changes except for global sclerosis consistent with the patient 's age ( fig .
immune deposits of igg , iga , igm , c1q , c3 , and fibrinogen were absent , despite the igm kappa m protein detected in the serum .
electron microscopy revealed irregularities , thinning and disintegration of the tubular basement membrane ( tbm ) . however , it was difficult to explain the patient 's massive ascites and rapidly progressive renal dysfunction according to the histological findings .
( a ) periodic acid - schiff ( pas ) stain ; magnification 10 ; ( b ) pas stain ; 200. light microscopy images show tubular dilatation and atrophy .
the glomeruli show global sclerosis and arterial intimal thickening , consistent with the patient 's age , without any other remarkable changes such as crescent formation . considering her advanced age ( 84 years of age ) and symptomatic relief after paracentesis ,
no further investigation was done and she was discharged with a serum cr level of 5.1 mg / dl 2 months after admission .
a 74-year - old woman was started on antihypertensive therapy 1 year prior to admission when she was noted to have a mild renal impairment with a serum cr level of 1.1 mg / dl .
she was status post - appendectomy at 20 years of age , had a history of ulcerative colitis with rectal cancer at 61 years of age , and a cataract at 68 years of age .
although her blood pressure was well controlled , her serum cr level rapidly increased to 1.5 mg / dl at 3 months after the start of antihypertensive therapy and 2.4 mg / dl at 5 months after the start of therapy .
she was subsequently referred to our hospital for further evaluation and treatment . on physical examination ,
the following laboratory results were obtained : wbc count , 6,800 wbc / mm ; rbc count , 24810 rbc / mm ; hb , 7.3 g / dl ; ht , 21.7% ; plt , 18.210/mm ; tp , 7.1 g / dl ; alb , 4.1 g / dl ; bun , 30 mg / dl ; cr , 3.6 mg / dl ; na , 138 meq / l ; k , 5.3 meq / l ; cl , 107 meq / l ; crp , 0.21 mg / dl ; plasma glucose , 107 mg / dl ; hba1c , 5.1% ; igg , 1,326 mg / dl ; igm , 76 mg / dl ; iga , 239 mg / dl ; c3 , 91 mg / dl ; c4 , 24.7 mg / dl ; and ch50 , 13 u / ml .
ana was negative , and mpo , pr3 , anca , and anti - gbm were not detected .
abdominal ct showed bilateral kidney enlargement that was not seen on an earlier ct exam 1 year previously .
4 . mri , including coronal magnetic resonance images , did not reveal multiple microcysts in the enlarged kidneys , however , a careful observation revealed multiple cysts along the corticomedullary boundary .
serial changes of abdominal computed tomography ( ct ) at ( a ) 2 years prior to admission , ( b ) 1 year prior to admission and ( c ) at admission in case 2 .
there is no evidence of kidney enlargement at 2 or 1 year prior to admission ; however , ct at admission shows kidney enlargement compared with the previous ct scans . magnetic resonance imaging ( mri ) of the abdomen : ( a ) axial section of the abdomen ( t1-weighted image ) and ( b ) coronal section of the abdomen ( t2-weighted image ) in case 2 .
no apparent microcysts are seen in the enlarged kidneys , including the coronal images , however , a closer observation shows multiple cysts along the corticomedullary boundary in the left kidney in the coronal section ( arrows ) ( b ) .
of seven glomeruli , two were globally sclerotic , one was segmentally sclerotic , and two showed glomerular cysts .
the distal tubules were also dilated , consistent with mckd , and there was mild interstitial fibrosis and inflammatory cell infiltration ( fig .
electron microscopy revealed irregular layering , spheroidizing , thinning , and partial rupture of the tbm .
the patient was treated with corticosteroids [ prednisolone ( psl ) 30 mg / day ] in view of the significantly elevated urinary -2 mg level and interstitial cell infiltration . immediately after psl administration ,
however , the serum cr level gradually increased and the hb level gradually decreased 2 months later , when psl was tapered .
three months after the start of psl therapy , the patient developed gastrointestinal bleeding and was found to have a serum cr level of 7 mg / dl .
however , no apparent bleeding source was detected by gastroscopy , colonoscopy , or enteroscopy .
anemia was corrected with blood transfusions , however , the patient 's renal function did not improve and she began hemodialysis therapy 5 months after referral .
( a ) periodic acid - methenamine - silver ( pam ) stain ; original magnification 10 , ( b ) pas stain original magnification 200. light microscopy images show tubular dilatation and atrophy .
cystic tubules show irregularities and thinning of the tubular epithelial cells . of seven glomeruli , two
we also performed immunohistochemical staining in both cases for cd10 , cytokeratin 7 ( ck7 ) , epithelial membrane antigen ( ema ) , e - cadherin , and cytokeratin ( 34 beta e12 ) to identify the level of tubular dilatation ( fig .
6 ) . in case 1 , the dilated tubules were negative for cd10 , a marker of proximal tubules ( 6 ) .
in contrast , immunostaining results for ck7 , ema , and e - cadherin , markers of the distal tubules and collecting ducts , were positive .
immunostaining results for ck ( 34 beta e12 ) , a marker of collecting ducts , were also positive ( 7 ) , indicating that the cysts predominantly arose from collecting ducts in case 1 . in case 2 ,
the dilated tubules were positive for ck7 and ema and weakly positive for e - cadherin and ck ( 34 beta e12 ) .
immunohistochemical staining for cd10 , cytokeratin 7 ( ck7 ) , epithelial membrane antigen ( ema ) , e - cadherin , and cytokeratin ( 34 beta e12 ) in the interstitium of both cases .
original magnification 10. the tubular basement membrane ( tbm ) of dilated tubules in both cases is negative for cd10 . in case 1 ,
the tbm of dilated tubules is positive for ck7 , ema , e - cadherin , and ck ( 34 beta e12 ) . in case 2 ,
the tmb of dilated tubules is positive for ck7 and ema and weakly positive for e - cadherin and ck ( 34 beta e12 ) .
nph - mckd is a hereditary disease of the renal tubules , which are important for the reabsorption of sodium and the concentration of urine .
typically , interstitial inflammation and fibrosis occurs , slowly progressing to eskd , similar to the progression seen in polycystic kidney disease .
the genetic mutations associated with nph - mckd are shown in table 1 ( 8 - 17 ) .
ar : autosomal recessive , ad : autosomal dominant recently , a human genetic condition termed ciliopathy has been proposed .
ciliopathy is thought to be caused by a dysfunction of two functionally and physically associated organelles , the centromere and the cilium .
autosomal dominant polycystic kidney disease ( adpkd ) and nph - mckd are thought to be related to renal cilia dysfunction ( ciliopathy ) , and more than 30 different genetic mutations have been localized to the cilia and/or centromeres ( 18,19 ) .
the disease onset occurs in early childhood or adolescence and typically progresses to eskd during adolescence . on the other hand
its onset occurs during adulthood and slowly progresses to eskd with the formation of multiple cysts , measuring 1 - 20 mm , in the corticomedullary boundary .
there is currently no effective treatment to prevent progression ; sodium supplementation and erythropoietin are used for symptomatic relief .
two types of mckd are recognized ( mckd1 and mckd2 ) according to the localizing chromosome and the onset of eskd .
mckd1 progresses more slowly than mckd2 and has a later onset of eskd ( average age 62 years old ; range , 50 - 70 years ) .
the average age of onset of eskd in mckd2 is 32 years ( range , 16 - 54 years ) .
genetic mutations are known to affect mucoprotein mucin-1 ( muc1 ) in mckd1 and uromodulin ( umod ) in mckd2 ( 10 ) .
the initial symptoms are polydipsia and polyuria due to decreased urine concentration and sodium loss .
generally , there is a slow progression to eskd , similar to the progression seen in polycystic kidney disease .
the typical ct , mri , and ultrasound images in mckd show atrophic kidneys with multiple cysts in the medulla , particularly at the corticomedullary junction ( 4,5 ) .
the differential diagnosis of kidney enlargement includes infiltrative diseases ( hematopoietic malignancy , sarcoidosis , and amyloidosis ) , autosomal dominant polycystic kidney disease , early stage diabetic nephropathy , acute interstitial nephritis , and pyelonephritis ( 20 ) . in the present cases , an immunohistological investigation revealed numerous microcysts within the dilated distal tubules and collecting ducts , compatible with mckd .
we postulate that these renal microcysts rapidly developed and replaced the renal parenchyma with tubulointerstitial inflammation , a finding rarely seen in mckd .
the cyst formation and subsequent inflammation played a pivotal role in the pathogenesis of the kidney enlargement and dysfunction .
all five of these cases showed renal enlargement and mckd - like tubulointerstitial changes with a rapid progression to eskd .
however , there are no previous reports of patients with massive ascites and rapidly progressive renal failure in mckd .
taneda et al . also reported a similar case in an elderly patient who was not clinically diagnosed , but had been diagnosed at autopsy with arpkd according to the renal morphology .
the case reported by taneda et al . also showed renal enlargement and a rapid progression to eskd in the absence of any apparent genetic mutation .
the diagnosis of arpkd was made according to the presence of liver involvement , including hepatic cysts , jaundice , and elevated liver enzyme levels , findings not typically observed in mckd ( 24 ) .
summary of similar cases reported in japan . because these other cases were reported mainly from japan
, it appears that these diseases are not due to regional or racial differences or a new disease type , unlike traditional hereditary mckd
. a greater accumulation of similar cases with genetic and histopathological analyses is important to further our understanding of this disease entity .
we herein reported two unusual cases that presented with rapidly progressive renal dysfunction , renal enlargement , and acute interstitial injury .
the pathological findings were consistent with mckd , however , the patients had no family history of renal disease .
similar cases , lacking the genetic findings of traditional hereditary mckd , have been reported in japan .
Output:
| medullary cystic kidney disease ( mckd ) is a hereditary disease associated with bilateral medullary polycysts and interstitial fibrosis .
mckd is typically associated with slowly progressive renal dysfunction .
we herein report two rare elderly cases with enlarged kidneys and rapidly progressive renal dysfunction without myeloperoxidase anti - neutrophil cytoplasmic antibody ( mpo - anca ) , pr3-anca , or anti - glomerular basement membrane ( gbm ) antibodies .
renal biopsies revealed extensive tubular dilatation and atrophy with interstitial fibrosis consistent with mckd .
both patients began hemodialysis therapy a few months later .
our cases suggest a mckd subgroup among elderly patients with an undefined genetic background , rapidly progressive renal dysfunction , and enlarged kidneys . |
PubmedSumm118663 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: the mobility of many stroke survivors is limited , and most identify walking as a top
priority for rehabilitation1 .
one way to
manage ambulatory difficulties is with an ankle - foot orthosis ( afo ) or a foot - drop splint ,
which aims to stabilize the foot and ankle while weight - bearing and lift the toes while
stepping1 . in stroke rehabilitation ,
various approaches , including robotic assistance , strength training , and
task - related / virtual reality techniques , have been shown to improve motor function2 .
the benefits of a high intensity stroke
rehabilitation program are well established , and although no clear guidelines exist
regarding the best levels of intensity in practice , the need for its incorporation into a
therapy program is widely acknowledged2 .
repetitive facilitative exercises ( rfe ) , which combine a high repetition rate and
neurofacilitation , are a recently developed approach to rehabilitation of stroke - related
limb impairment2,3,4,5 . in the rfe program ,
therapists use muscle spindle stretching and
skin - generated reflexes to assist the patient s efforts to move an affected joint5 .
previous studies have shown that an rfe
program improved lower - limb motor performance ( brunnstrom recovery stage , foot tapping , and
lower - limb strength ) and the 10-m walk test in patients with brain damage3 .
an afo is an assistive device to help stroke patients with hemiplegia walk and stand .
a
properly prescribed afo can improve gait performance and control abnormal kinematics arising
from coordination deficits6 .
gait training
with an afo has been also reported to improve gait speed and balance in post - stroke
patients7 , 8 .
therefore , we hypothesized that short - term physiotherapy combining rfe and orthotic
treatment would improve both lower - extremity motor performance and functional ambulation .
the present study aimed to confirm the efficacy of a combination therapy consisting of rfe
for the hemiplegic lower limb and gait training with afo .
the subjects consisted of 27 inpatients ( 24 males and 3 females ) diagnosed with cerebral
hemorrhage ( 15 patients ) or cerebral infarction ( 12 patients ) .
the patients average age was
59.3 12.4 years ( 3373 years ) , the duration after onset was 35.7 28.9 months ( 5115
months ) , and brunnstrom stage medians and quartiles of the hemiplegic lower limb were stage
4.0 and 44.5 ( stage 36 ) , respectively .
eleven patients had right hemiplegia , and 16
patients had left hemiplegia . among the 27 study participants , one used a rigid afo with a
medial stainless steel upright9 , two used
a posterior spring leaf10 , and 24 used a
hinged afo10 .
the inclusion criteria were as follows : age , 3080 years ; hemiplegia of the lower limb
( brunnstrom stage 36 ) ; ability to walk without assistance using a t - cane and/or afo ;
diagnosis of hemiplegia due to stroke ; morbidity period , 5 months or more ; ability to
understand the purpose of the study and follow instructions , and agreement to participate in
this study .
the exclusion criteria were as follows : onset of stroke , < 4 weeks previously ;
abnormal gait prior to the onset of stroke ( such as joint disability or peripheral
neuropathy ) ; any medical condition that limited the study design ( such as severe
cardiopulmonary disease or severe sensory disturbance ) ; severe aphasia and dementia that
made it impossible to follow verbal instructions ; and lesions on both sides of the cerebral
hemisphere .
the
study was conducted after obtaining approval from the ethics committee of the tarumizu chuo
hospital , and all participants provided written informed consent .
intervention was combination therapy
consisting of rfe for the hemiplegic lower limb and gait training with afo . according to a
previous study ,
all subjects underwent an rfe program consisting of 7 specific exercise
patterns3 , which were used to elicit
movement of the hip , knee , and ankle in a manner designed to minimize synergistic movements .
this technique involved the use of rapid passive stretching of the muscles in conjunction
with tapping and rubbing the skin to assist in generating contractions of the targeted
muscles5 .
exercises were performed as
two sets of 50 repetitions with a 12 minute rest period in between sets5 .
in addition , all patients underwent gait
training with a self - made afo .
this intervention was performed 40 minutes / day , 6 days / week for 4 weeks .
the outcome measures used to
assess motor performance were the fugl - meyer assessment of the lower extremity ( fma - le)11 and the stroke impairment assessment set
( sias)12 .
functional ambulation was
assessed with a timed up & go test ( tug)13 and a 10-m walk test ( 10mwt ) . to determine whether physiotherapy that combined rfe and orthotic treatment improved the
lower - limb motor performance and functional ambulation , the wilcoxon signed - rank test was
performed , because the shapiro - wilk s test showed that the data were not normally
distributed .
the analysis was performed with the statistical analysis program spss
statistics for windows version 22.0 ( ibm corporation , armonk , ny , usa ) with a significance
level of =0.05 .
table 1table 1.lower-limb motor performance and functional ambulation at the baseline and after
the combining trainingoutcome measurementsbaselineafter the trainingdifference mean sdfma - le22.96 4.0725.85 4.032.89 2.99**sias46.59 8.3453.63 7.637.04 4.60**tug ( sec)17.35
5.5714.02 4.463.33 3.52**10mwtcgs ( m / sec)0.68 0.220.81 0.240.12 0.09**fgs ( m / sec)0.80 0.280.96 0.310.16 0.16****significant difference p<0.01 .
sd : standard deviation ; fma - le : the fugl - meyer
assessment of the lower extremity ; sias : stroke impairment assessment set ; tug : timed
up & go
test ; 10mwt : 10-m walk test ; cgs : comfortable gait speed ; fgs : fast gait
speed shows the changes in fma - le , sias , tug , and 10mwt ( comfortable gait speed and
fast gait speed ) . in terms of lower - limb motor performance ,
fma - le increased significantly
from 22.96 4.07 to 25.85 4.03 ( p<0.01 ) , and sias increased significantly from 46.59
8.34 to 53.63 7.63 ( p<0.01 ) . in terms of functional ambulation ,
tug decreased
significantly from 17.35 5.57 seconds to 14.02 4.46 seconds ( p<0.01 ) , comfortable
gait speed increased significantly from 0.68 0.22 ( m / sec ) to 0.81 0.24 ( m / sec )
( p<0.01 ) , and fast gait speed increased significantly from 0.80 0.28 ( m / sec ) to 0.96
0.31 ( m / sec ) ( p<0.01 ) . * * significant difference p<0.01 .
sd : standard deviation ; fma - le : the fugl - meyer
assessment of the lower extremity ; sias : stroke impairment assessment set ; tug : timed
up & go
test ; 10mwt : 10-m walk test ; cgs : comfortable gait speed ; fgs : fast gait
speed
in this study , short - term combination therapy consisting of rfe and orthotic treatment was
conducted to improve the lower - limb motor performance and functional ambulation of chronic
post - stroke patients .
there were statistically significant improvements in fma - le , sias ,
tug , and 10mwt after the intervention .
furthermore , the results of the 10mwt at a fast gait
speed reached the minimal detectible change threshold ( 0.13 m / s)14 .
recently , some systemic reviews of afo have reported that gait training with afo can
improve walking ability and balance in people with stroke1 , 15 .
however , few studies
have focused on the correlation between afo and motor performance changes of the lower limb
in post - stroke patients16,17,18 .
changes seen in
this study were more marked in the lower - limb motor performance , with a substantial
clinically meaningful change in fast walking speed ( 0.13 m / s ) being achieved by all
participants who completed the study protocol .
the results of this study show that
short - term combination therapy consisting of rfe and gait training with afo may enhance
lower - limb motor function , thereby improving walking ability in patients with chronic
stroke , which is beneficial for comprehensive stroke treatment .
several studies suggested that rfe might promote functional recovery of hemiplegia and
activities of daily living to a greater extent than conventional neurofacilitation therapy ,
using a randomized controlled design2,3,4,5 , 19 , 20 .
especially , rfe with other interventions
( i.e. , neuromuscular electrical stimulation , direct application of vibratory stimulation
repetitive transcranial magnetic stimulation , and pharmacological treatments ) may be more
effective than rfe only for the recovery of limb motor performance . in the present study ,
patients who received rfe with gait training with afo showed significant functional and
ambulatory improvements .
this study had some limitations because it involved a small number of subjects , and its
intervention period of four weeks was short .
in addition , this was not a randomized
controlled trial , and the efficacy of rfe with orthotic treatment could not be compared ;
therefore , it is difficult to generalize its results . further , this study could not exclude
observer bias and subject bias because the same staff implemented assessment and
training . in conclusion , the differences in fma - le , sias , tug , and
10mwt demonstrated that
application of a short - term combination therapy consisting of rfe and orthotic treatment has
beneficial therapeutic effects on improving functional ambulation and motor performance of
the lower limb in chronic post - stroke patients .
Output:
| [ purpose ] this study investigated the short - term effects of a combination therapy
consisting of repetitive facilitative exercises and orthotic treatment . [ subjects and
methods ] the subjects were chronic post - stroke patients ( n=27 ; 24 males and 3 females ;
59.3 12.4 years old ; duration after onset : 35.7 28.9 months ) with limited mobility and
motor function .
each subject received combination therapy consisting of repetitive
facilitative exercises for the hemiplegic lower limb and gait training with an ankle - foot
orthosis for 4 weeks .
the fugl - meyer assessment of the lower extremity , the stroke
impairment assessment set as a measure of motor performance , the timed up & go test ,
and the 10-m walk test as a measure of functional ambulation were evaluated before and
after the combination therapy intervention .
[ results ] the findings of the fugl - meyer
assessment , stroke impairment assessment set , timed up & go test , and 10-m walk test
significantly improved after the intervention .
moreover , the results of the 10-m walk test
at a fast speed reached the minimal detectible change threshold ( 0.13 m / s ) .
[ conclusion ]
short - term physiotherapy combining repetitive facilitative exercises and orthotic
treatment may be more effective than the conventional neurofacilitation therapy , to
improve the lower - limb motor performance and functional ambulation of chronic post - stroke
patients . |
PubmedSumm118664 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: a 2-month - old girl was brought to us with haziness of both eyes for the past 20 days .
she was a full - term baby delivered by cesarean section with a birth weight of 2.75 kg .
the parents denied any history of trauma and the child was otherwise healthy . on examination ( under general anesthesia ) , she was noted to have conjunctival hyperemia , increased corneal diameter ( 13.5 mm od , 11 mm os ) , corneal haze with small blood clots in the anterior chamber of both eyes .
intraocular pressure ( iop ) was noted to be 20 mm hg od and 8 mm hg os by perkin 's tonometer .
a few yellowish - orange skin nodules were noted on the forehead and neck [ fig .
2 ] , that progressively increased on follow - up . remainder of her systemic and neurological examination was normal .
excision biopsy of a forehead skin lesion was performed under general anesthesia and histopathological examination of the specimen showed non - langerhans histiocytic proliferation [ fig . 3 ] .
immunohistochemistry was negative for cd1a and cytokeratin ; positive for cd68 . with the above clinical picture and laboratory finding
left , corneal edema right eye ; top right : hyphema after resolution of corneal edema left eye ; bottom left : development of cataract ; bottom right : after cataract extraction resolution of skin lesion over the period of 1 year histopathology of skin lesion .
low power ( 100 ) : structure of acanthotic skin with sub epidermal infiltration of xanthomatous cells ( arrow ) and inflammatory cells with encircling adnexal structure and extending into subcutaneous zone .
high power ( 1000 ) : sheets of foamy histiocytes ( arrow ) with interspersed multinucleated giant cells ( block arrow ) she was started on a topical antibiotic steroid combination , cycloplegic and dorzalamide ou . on her review visits , she developed posterior synechiae and a few iris nodules in the left eye , which resolved with intensive topical steroids .
she maintained a steady central fixation throughout her treatment and was also on regular review with a pediatrician .
four months after her first presentation , she developed bilateral anterior subcapsular cataract , which gradually progressed .
topical prednisolone acetate 4 times a day was added to topical antibiotics a day before surgery .
after peritomy , the bleeders were cauterized and a limbal groove made with a blade breaker .
the anterior chamber was entered by deepening the groove and trypan blue was injected under an air bubble .
the anterior capsule was punctured by a bent 26 g needle and capsulorhexis done with a utrata forceps .
the bottle height was raised to increase pressure in the anterior chamber and tamponade any bleeding .
subsequently , the posterior capsule was punctured by a bent 26 g needle in a sideways fashion and capsulorhexis completed by an utrata forceps .
an intraocular lens ( iol ) was not implanted given the age of the patient ( < 1 year ) .
after surgery , she was started on topical steroid antibiotic combination and cycloplegics , which were tapered over 6 weeks .
the right eye cataract surgery was done 6 weeks after the left eye surgery and a similar procedure was followed .
1 year after surgery , the child was comfortable with aphakic correction and the visual axis was clear .
the iop was noted to be normal on all occasions and no antiglaucoma medications were needed .
touton 's giant cells were absent in our patient ; however , she had features suggestive of a non - langerhan 's cell histiocytosis as suggested by the absence of a cd1a and cytokeratin .
ocular involvement in jxg is in the form of diffuse or discrete vascular iris nodules , which may bleed , resulting in spontaneous hyphema and secondary glaucoma .
the condition may also involve the ciliary body , anterior choroid , cornea , lids , limbus , orbit , retina , optic nerve and optic nerve , but intraocular involvement is rare ( < 1% of cases ) .
indeed jxg should be included in the differential diagnosis of spontaneous hyphema in this age group and one should make a careful evaluation to detect skin nodules , which can be difficult to detect early in dark skinned individuals .
this could be because patient was taken up for surgery once the iris nodules and hyphema had resolved and patient was continued on topical steroids .
it is likely that the use of intracameral adrenaline , raising the bottle height and a tight wound closure reduced the risk of bleeding in our patient . in general ,
bimanual anterior limbal vitrectomy is preferred over a pars plana vitrectomy after primary posterior capsulotomy in pediatric cataract surgery .
this is because the technique is simpler and most cataract surgeons are comfortable with an anterior approach .
an iol was not implanted in our patient considering the anterior segment inflammation and the bilaterality .
furthermore , the safety and benefits of iol implantation in infancy is not well - established .
management as detailed above may reduce the risk of bleeding and improve the visual outcome .
Output:
| there is limited literature on the management of cataracts in juvenile xanthogranuloma ( jxg ) .
a 2-month - old girl presented to us with hyphema , secondary glaucoma ou and skin nodules suggestive of jxg .
she developed bilateral cataracts during her follow - up and was treated successfully with cataract surgery and aphakic rehabilitation . |
PubmedSumm118665 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input:
Output:
| using geographic information systems ( gis ) and routinely collected data , we explored whether childhood residence near busy roads was associated with asthma in a low - income population in san diego county , california .
we examined the locations of residences of 5,996 children [ less than / equal to ] 14 years of age who were diagnosed with asthma in 1993 and compared them to a random control series of nonrespiratory diagnoses ( n = 2,284 ) .
locations of the children 's residences were linked to traffic count data at streets within 550 ft .
we also examined the number of medical care visits in 1993 for children with asthma to determine if the number of visits was related to traffic flow .
analysis of the distribution of cases and controls by quintiles and by the 90th , 95th , and 99th percentiles of traffic flow at the highest traffic street , nearest street , and total of all streets within a 550-ft buffer region did not show any significantly elevated odds ratios . however , among cases , those residing near high traffic flows ( measured at the nearest street ) were more likely than those residing near lower traffic flows to have two or more medical care visits for asthma than to have only one visit for asthma during the year .
the results of this exploratory study suggest that higher traffic flows may be related to an increase in repeated medical visits for asthmatic children
. repeated exposure to particulate matter and other air pollutants from traffic exhaust may aggravate asthmatic symptoms in individuals already diagnosed with asthma.imagesfigure 1 |
PubmedSumm118666 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: in 1652 , pietro marchetti , a surgeon from padua , observed an elongation of the styloid process related to an ossifying process of the stylohyoid ligament .
it was eagle ( 1937 and 1949 ) who first defined stylalgia as an autonomous entity related to abnormal length of the styloid process or to mineralization of the stylohyoid ligament complex.1
,
2 eagle s syndrome was described by eagle as styloid process of more than 25 mm long , or when there is calcification of the stylomandibular ligament .
it can cause pharyngeal and cervical pain on swallowing , speaking , opening of the mouth , or during movement of the cervical region , sensation of a foreign body in the oropharynx , or pain radiating to the ear.4
,
5
the etiology and pathogenesis of this syndrome are controversial . according to eagle ,
a previous surgical trauma such as tonsillectomy , or a chronic irritation of the stylomandibular ligament , could cause osteitis , tendonitis , or periostitis , which could lead to reactive ossifying hyperplasia of the styloid process .
other authors have suggested hypotheses such as osseous metaplasia of the reichert cartilage residues , persistence of mesenchymal elements capable of producing bone tissue in adults , and ossification of the stylohyoid ligament related to endocrine disorders .
the frequency of ossification of the styloid chain styloid process , stylohyoid ligament and greater horn of the hyoid bone has been found to vary from 4% to 30% and to be mostly asymptomatic .
eagle estimated the frequency of 34% for symptoms in patients presenting an elongated styloid process .
only 4 to 10.3% of patients with an elongated styloid process are reported to experience pain .
eagle postulated that there are two types of the syndrome that came to bear his name : the classic type and the carotid artery type .
the average length of the styloid process has been shown to be less than 3 cm with the normal length ranging from 1.52 cm to 4.77 cm ; only 11 of 2,000 cranial dissections have detected a styloid process longer than 4 cm .
however , the length of the styloid process has not been found to be correlated to the severity of pain . in this report
, we describe a case of eagle s syndrome that was characterized by a broad tenderness in left lateral and posterior cervical as well as temporal regions .
a 50-year - old female presented to shahed university dental school with a 3-year history of a small swelling on her left lateral pharyngeal region .
she also had a sharp pain for one year on the left side of her neck radiating to temporal and posterior cervical regions .
the pain had lead to a disability in raising the left arm even for daily activities .
patient had sought medical care for the pain several times without a definitive diagnosis or treatment .
in the extra - oral examination ,
temporomandibular joint was found to be normal , and maximum mouth opening was in the normal range .
the mineralized process was palpable in the left lateral pharyngeal region , and was associated with tenderness .
a panoramic radiograph was taken ( figure 1 ) , and a diagnosis of eagle s syndrome was made based on clinical and radiographic findings .
under local anesthesia and intravenous sedation , resection of approximately two - thirds of elongated styloid process was performed ( figure 2 ) . in three day follow - up , patient was completely symptom - free .
the styloid process is a slender bony projection arising from the lower surface of the petrous portion of the temporal bone .
this process originates from reichert s cartilage of the second brachial arch and persists as a structure running from the base of the skull to the lesser horn of the hyoid , passing between the internal and external carotid arteries .
elongation of the styloid process or stylohyoid ligament calcification is a well recognized finding of dental practice .
most cases are asymptomatic ; however , a small number of such patients experience symptoms of eagle s syndrome , related to the compression of adjacent nerves and blood vessels .
the length of the styloid process is individually variable and according to lindeman , it is 2 - 3 cm long .
long styloid process has been defined as more than 4 cm , since in this situation , the highest incidence of eagle s syndrome occurs . but according to recent studies , the normal range of its size varies from 1.52 to 4.77 cm .
the elongation length styloid process in the present case was comparable to the above - mentioned findings , as the surgically removed portion was 3 cm and at least 1 cm was left intact .
this syndrome is found more often in females and affects subjects more than 50 years old most often , as did in our case .
eagle proposed surgical trauma or local chronic irritation could cause consequent reactions like ossifying hyperplasia . later , different hypotheses formulated such as osseous metaplasia of the reichert cartilage residues , persistence of mesenchymal elements capable of producing bone tissue in adults , and ossification of the stylohyoid ligament related to endocrine disorders in women at menopause . in this case , since the patient did not have a history of trauma to the region , the pathogenesis is likely to be related to endocrine disorders of the patient who was at menopause .
in cases reported by eagle , pharyngeal discomfort associated with elongated styloid process
including vague facial pain , especially while swallowing , turning the head , or opening the mouth was present .
however , the present case exhibited a broad tenderness in the neck and left arm , without any facial pain .
other symptoms may include dysphagia , dysphasia , otalgia , dizziness , and transient syncope .
eagle originally described two distinct syndromes : the classic eagle s syndrome ( classical stylohyoid syndrome ) and carotid artery syndromes ( stylocarotid syndrome ) .
the classic eagle s syndrome develops by fibrous tissue formation in the area of a mineralized stylohyoid complex , distorting the cranial nerve endings in the tonsillar fossa following tonsillectomy .
it is characterized by dull and persistent pharyngeal pain especially in the tonsillar area , accompanied occasionally by dysphagia and painful swallowing , foreign body sensation , as much as facial and/or cervical pain .
a second form of this condition which is not dependent upon tonsillectomy is known as carotid artery syndrome or stylocarotid syndrome .
the elongated , mineralized complex is thought to impinge on the internal or external carotid arteries and associated sympathetic nerve fibers .
the patient s compliant is cervical pain while turning the head , i.e. when the carotid artery is compressed , which may be radiated to the other sites the artery supplies . in order to diagnose eagle s syndrome ,
it is necessary to obtain an accurate case history to define the type of the syndrome.12
,
13 in our case , an intense pain in the left lateral region of the neck radiating to the temporal and posterior cervical regions was present . since the elongated apparatus compresses the adjacent nerves , palpation of the neck near the trapezius muscle elicited tenderness and the pain radiated to her ipsilateral arm .
these findings directed us to diagnose the second type of eagle s syndrome ( stylocarotid syndrome ) .
the treatment for eagle s syndrome may be medical or surgical . medical treatment consists of infiltration of steroids or local anesthetics , or oral administration of carbamazepine .
however , the long - term results of medical treatment are not satisfactory . the styloid process may be partially removed by intra- or extra - oral approaches .
the extra - oral approach has the advantage of providing better visualization of the operative field , and it is possible to resolve any vascular injury without major complications . however , there are some disadvantages , such as the complexity of the technique that demands longer operating time , and an external scar that is not cosmetically pleasing .
the intra - oral approach has advantages over the extra - oral technique in that it is quicker and easier to perform , eliminates the need for extensive dissection considering the risks in the cervical region , and does not leave an external scar .
other factors other than only a long styloid process may give rise to eagle s syndrome .
an accurate case history and the specialist s intuition are fundamental to the differential diagnosis regarding several other pharyngo - cranio - facial pain disorders .
eagle s syndrome should be considered in the evaluation of patients with recurrent throat and neck pain . in the opinion of the authors , surgical treatment
should be the first choice with the trans - oral approach being the preferable technique .
this approach avoids potential injury to important structures of the maxillo - vertebro - pharyngeal space and is characterized by a short operation as well as an absence of visible scars and reduced hospitalization period .
Output:
| elongation of the styloid process or stylohyoid ligament calcification is a well recognized finding of dental prac - tice , and an incidence of 4 to 30 percent has been reported on radiographs .
rarely , complete mineralization of the stylohyoid ligament or elongation of styloid process has been associated with difficulties in intubation and significant clinical symptoms , which is termed eagle s syndrome , and it exhibits dull or sharp intermittent pain felt along the glossopharyngeal nerve that is located in the hypopharynx and at the base of the tongue and recurrent throat pain or foreign body sensation , dysphagia , or facial pain . additional symptoms may include neck or throat pain with radiation to the ipsilateral ear . in the case
presented , the elongated process caused a broad tenderness in left lateral and posterior cervical as well as temporal regions . |
PubmedSumm118667 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: the patient described in this case report provided written consent to the use of all medical information disclosed in this publication independent of general hospital admission consent .
a 60-year - old african american female with morbid obesity , hypertension , untreated obstructive sleep apnea , and chronic kidney disease ( stage 3 ) presented at urgent care with significant low back pain ( lbp ) and a racing heart .
after an ekg was performed , the patient was found to be in new onset af with rapid ventricular response .
she was transferred to abbott northwestern hospital emergency department ( ed ) for further evaluation and care .
her vital signs on admission were as follows : bp , 174/81 mmhg ; pulse , 124 bpm ; height , 1.651 m ( 5'5 ) ; and weight , 153.3 kg ( 338 lb ) .
she was currently on leave from work due to the significance of the lbp and previously had been diagnosed with l5-s1 moderate disc herniation , mild l4 - 5 central spinal stenosis , grade i spondylolisthesis , and mild to moderate l3-l4 central spinal stenosis .
she had recently taken a 1-week course of prednisone with no improvement in her symptoms .
she refused narcotics for pain management in the ed and throughout her hospital admission . in the ed , she was started on medical therapy according to the af protocol : ( 1 ) intravenous heparin 25 000 units in d5w 250 ml , 1650 units / h continuous ; ( 2 ) intravenous heparin 3100 units injection ( 1000 units / ml ) one time ; ( 3 ) intravenous diltiazem 100 mg in d5w , 100 ml 10 to 15 mg / h continuous ; and ( 4 ) intravenous diltiazem 15 mg injection ( 15 mg of 25 mg/5 ml ) one time .
additional medications included ( 1 ) medrol dosepak ( pfizer inc , new york ) 8 mg twice daily ; ( 2 ) acetaminophen 650 mg , every 4 hours as needed ; ( 3 ) aspirin 325 mg one time ; ( 4 ) lorazepam 1 mg , every 4 hours as needed ; ( 5 ) ondansetron 4 mg injection every 6 hours as needed ; and ( 6 ) tramadol 50 to 100 mg tablet ( 1 - 2 50 mg tablet ) as needed .
the patient was admitted to the cardiac telemetry unit , and electrocardioversion was scheduled 36 hours later in the event that medical treatment was not effective .
pgihh received a nurse referral to see the patient for back pain and anxiety ; she was seen approximately 21 hours after hospital admission ( 25 hours after confirmed tachycardia and af in urgent care ) .
a self - report 10-point rating scale ( 0 = no symptom present , 10 = worst possible symptom imaginable ) commonly used in inpatient settings was used to rate pain , anxiety , and nausea .
the patient reported acute pain ( 8/10 ) , complained of nausea ( 6/10 ) , and was extremely anxious ( 10/10 ) .
the patient was experiencing emesis as the practitioner arrived in her room and was writhing in pain .
although unfamiliar with cam approaches or modalities , the patient was open to trying any treatments that might help decrease her pain , nausea , and anxiety .
based on the i m practitioner 's clinical experience and familiarity with relevant research , a multimodality approach was selected .
first , the environment in the room was adjusted ( lights dimmed , calming music played on the hospital 's continuous ambient relaxation environment [ care ] channel , door closed , and sign placed on door to prevent interruptions ) to promote a more relaxing setting .
the following modalities were used ( listed chronologically ) in the 45-minute session : ( 1 ) clinical aromatherapy using 2 drops of spearmint ( mentha spikata ) essential oil placed on a cotton ball for inhalation and another 2 drops added to 5 cc ( to obtain a 2% solution ) of massage lotion ; ( 2 ) guided imagery in which the patient was encouraged to picture herself in a peaceful place and focus on a positive image to encourage the relaxation response ; ( 3 ) korean hand therapy , with 5 beads being placed on the area of the patient 's hand corresponding to the area of her back pain ; and ( 4 ) bilateral foot massage using gliding , kneading , and holding with gentle pressure . during the session the patient visibly relaxed , her breathing slowed and deepened , and her physical agitation markedly decreased .
the i m practitioner noted her heart rate to be 40 bpm , and the registered nurse ( rn ) was immediately informed . upon consultation
, the rn immediately turned off the heparin , and it was suspected that the patient had converted to normal sinus rhythm .
an ekg was ordered and confirmed the patient had indeed converted during the time of the session ( figure ) .
this was clinically confirmed by the electro - physiology nurse practitioner and the attending cardiologist . when requested at the end of the session ,
the patient 's post - treatment scores were ( 1 ) pain : 5/10 ( 37.5% reduction ) , ( 2 ) nausea : 4/10 ( 33.3%reduction ) , and ( 3 ) anxiety : 5/10 ( 50% reduction ) .
no general or af protocol medication changes were made prior to the i m intervention .
the patient remained in normal sinus rhythm ( nsr ) , and was discharged the following day without the scheduled electrocardioversion . in a follow - up conversation 2 months after discharge , the patient stated she had not had any additional i m treatments , hospitalizations , or similar symptoms ( ie ,
pre - treatment electrocardiogram [ ekg ] ( day of admission : 18:05 , confirmed ekg findings in urgent care ) , a , in comparison to post - treatment ekg ( day after admission : 14:59 ) , b.
the possibility exists that the patient 's rhythm would have converted without intervention , as many patients with lone af of short duration do convert spontaneously to a sinus rhythm , including those patients who develop af after an acute life stressor .
a final option is that i m played a major role in the patient 's conversion to nsr .
the impact of i m is worth consideration because ( 1 ) the patient had not converted spontaneously within 24 hours of admission , ( 2 ) pharmacologic intervention up to the point of i m treatment ( 26 hours ) had been ineffective , and ( 3 ) the conversion to nsr occurred during the i m session .
previous research suggests that during an acute coronary event , patients perceive both intense pain and extreme distress . the severity of pain experienced during an event is directly correlated with the level of psychological distress : 3 out of 4 patients with acute coronary syndrome report moderate or high stress explicitly because of the severity of pain during the event .
it is reasonable to consider the pain - stress relationship in a different cardiac population and how treatment options aimed at targeting this relationship could be clinically beneficial .
the stress response ( sr ) or fight - or - flight response is a mind - body state of hyper - arousal involving unconscious physiological mechanisms ( eg , increased heart rate , blood pressure , respiration , and availability of energy stores ) that prepare a given organism to successfully survive stressful experiences . the relaxation response ( rr ) is a mind - body state with a coordinated physiological response that is characterized by measurable reductions in volumetric oxygen and carbon dioxide consumption , respiratory rate , systolic blood pressure , diastolic blood pressure , and arterial blood lactate .
since many of the physiological changes occur in the opposite direction to those of the sr , the rr has been hypothesized as its physiological counterpart .
accordingly , the rr is widely utilized clinically in outpatient and inpatient communities to counteract the undesired physiologic and psychological effects of stress .
it is therefore reasonable to consider that by activation of the parasympathetic nervous system , the physiological response is in some way associated with the conversion to nsr .
other related biological changes may well occur during i m interventions but are not as easily documented .
finally , i m therapies could provide a more cost - effective approach when considering the overall burden of healthcare costs ; in this case , additional hospitalization , electrocardioversion , and general anesthesia were avoided .
although the i m intervention was likely successful in restoring cardiac rhythm in one patient , it is difficult to conclusively determine that i m was the cause of the spontaneous conversion to nsr .
it is possible that spontaneous conversion to nsr could have occurred at the discrete point in time independent of i m intervention .
it is noteworthy that nsr conversion occurred 25 hours after medical treatment was initiated and during the i m session ( after the patient 's marked pain and anxiety were reduced by i m ) .
the majority of patients with af of less than 72 hours ' duration converted spontaneously to nsr , with a duration of less than 24 hours being the best predictor .
in addition , the level of overall distress in this particular patient was significantly higher than that in the majority of patients seen by the telemetry department . consequently , the results are more striking considering the severity of the situation . as a result , a holistic approach using a variety of i m modalities might be beneficial to consider in a patient with similar acuity and may give clinicians and researchers alike a better sense of what patient populations to consider for i m therapies .
generally , imps use 1 to 3 modalities ; more were used in this case due to the severity of the patient 's clinical pain , anxiety , and nausea .
it is therefore difficult to determine which modality was most effective and to determine a clinically appropriate dose of a specific therapy .
lastly , a larger study with a more robust methodology investigating af , pain , stress , and the pain - stress relationship necessitates consideration as a case report can have considerable statistical and methodological limitations .
in patients with new onset af who are in acute pain and who do not convert spontaneously , an i m approach is worth consideration . in this case , the treatment provided was brief and safe and quantitatively improved pain , anxiety , and nausea scores .
furthermore , because spontaneous conversion to nsr occurred during the i m session , it remains a possible treatment approach for spontaneous conversion to nsr .
Output:
| the relationship between acute life stress and the development of atrial fibrillation ( af ) has been noted in the literature .
however , the use of integrative medicine ( i m ) in restoring cardiac rhythm has not been adequately studied .
this case report describes how an i m approach was used in a patient with atrial fibrillation and acute pain .
spontaneous cardioversion to normal sinus rhythm occurred during the i m session , in addition to marked decreases in self - reported pain , anxiety , and nausea at the conclusion of i m treatment .
these results provide initial support that for some cases of af , i m therapies can help to reduce costs via avoidance of additional hospitalization , electrocardioversion , and general anesthesia . |
PubmedSumm118668 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: sedation induction is one of the most important and sometimes most difficult stages of carrying out a diagnostic or therapeutic procedure in children ( 1 ) .
children not cooperating for diagnostic evaluations such as computed tomography ( ct ) scan and magnetic resonance imaging are among the most common cases of using procedural sedation and analgesia ( psa ) in emergency departments ( ed ) .
an ideal sedative drug should be rapid and short - acting , with minimum side effects on the patients respiratory condition and hemodynamic .
various drugs such as chloral hydrate , phenobarbital , propofol , midazolam , and etomidate are among the available drugs for this purpose yet , selection of the safest and most efficient drug and its proper dose for sedation are a matter of debate ( 2 - 4 ) .
many of pediatric patients do not receive enough drug due to concerns about probable side effects of the drug ( 5 ) .
midazolam has turned into a common drug for induction of sedation in eds as a result of its short half - life , various methods of prescription and less pain at the time of injection .
this relatively short - acting benzodiazepine has anti - stress , sedative , anti - seizure , and muscle relaxant effects .
singh et al . showed that use of intravenous ( iv ) midazolam with a 0.2 mg / kg dose , can induce proper sedation with minimum side effects for pediatric imaging ( 6 ) .
however , there is not much data regarding its proper dose and potential side effects especially in the iranian children population .
therefore , the present study was done to compare 2 doses of iv midazolam in sedation induction for doing brain imaging in infants .
the present clinical trial was performed to compare 0.1 and 0.3 mg / kg doses of iv midazolam in induction of sedation for infants in need of brain ct scan following head trauma .
the infants presented to the ed of golestan and imam khomeini hospitals , ahvaz , iran , during april 2014 to march 2015 were studied .
after completely explaining the study protocol to the parents , informed consent form was filled for each participant to enter the study .
if the parents were not content with the study process or did not want their infant to continue participating at any stage , the infant was excluded .
the present study has been registered on the iranian registry of clinical trials ( irct ) under the number and approved by the ethics committee of ahvaz jundishapour university of medical sciences .
infants presented to the ed following head trauma in need of sedation induction for undergoing brain ct scan were enrolled .
exclusion criteria consisted of high probability of difficult airway , history of uremia and allergy to benzodiazepine , presence of hemodynamic instability , congestive heart failure , liver diseases , decreased level of consciousness , uncontrolled vomiting , history of reflux , and simultaneous use of opioids .
all patients were prepared with a proper peripheral iv line and continuous heart , blood pressure , pulse rate , and pulse oximetry monitoring .
group a , received iv midazolam with 0.1 mg / kg dose , while the dose was 0.3 mg / kg for group b. the goal was reaching sedation level of 3 or 4 based on ramsay scale ( 7 ) . not reaching the desired level of sedation
iv ketamine with 1 mg / kg dose or another dose of midazolam was used .
all injections were done via the peripheral vessel using a blue or yellow angiocatheter , and slowly during 10 seconds .
brain ct scan indication was decided by an emergency medicine specialist based on the standard protocols of advanced trauma life support ( atls ) .
injections were done by trained nurses under supervision of a senior emergency medicine resident . over the course of the procedure ,
all the required equipment for probable need for airway management were present at the patients bedside .
we should note that the physician prescribing the drugs and the patients parents were blinded to the drug dose .
a checklist consisting of demographic data and pharmacodynamics ( onset and duration of action and side effects ) was filled for all the patients in both groups .
drop of oxygen saturation to < 95 , decreased blood pressure , inconsolable crying , restlessness and anxiety , hiccup , opisthotonus , seizure , nausea and vomiting , and respiratory depression and apnea were among the studied side effects .
statistical analysis :
sample size .
quantitative data were reported as frequency and percentage , and qualitative ones as mean standard deviation .
chi - square and independent sample t - test were used for comparing data between two groups .
110 infants with the mean age of 14.0 5.9 months ( range : 4 - 24 ) and mean weight of 9.7 2 kg ( range : 5 - 15 ) were randomly allocated to one of the 2 study groups ( 54.6% female ) .
success rate in 0.1 and 0.3 mg / kg groups were 38.2% ( 21 patients ) and 60% ( 33 patients ) , respectively ( p = 0.018 ) .
overall , 56 ( 50.9% ) patients did not reach proper sedation and were sedated receiving ketamine ( 22 patients ) or another dose of midazolam ( 34 patients , mean additional dose needed was 2.1 1.1 mg ) .
table 2 compares the therapeutic characteristics and side effects of the 2 doses of midazolam .
the results of the present study demonstrated the higher success rate and longer duration of action for 0.3 mg / kg midazolam compared to 0.1 mg / kg .
the groups were equal regarding onset of action , effect on vital signs and probable side effects .
baseline characteristics of studied patients the number of patients in each group = 55 ; measures presented as number ( % ) or mean standard deviation .
comparison of outcomes between two studied groups : not reaching the sedation level of 3 or 4 based on ramsey scale ; the number of patients in each group = 55 ; measures presented as number ( % ) or mean standard deviation . facing children in ed
presentation of a pediatric trauma patient , accompanied by restless parents , to an overcrowded ed has been a nightmare for emergency medicine physicians , especially if a diagnostic and therapeutic procedure is required . the need for keeping the child motionless during procedures , has made using psa inevitable for this age group .
being familiar with various kinds of available drugs and their dosage is a necessary skill for all emergency physicians .
therefore , the present study was designed and carried out to compare the effectiveness and side effects of two different iv midazolam doses . in the study by singh et al . , midazolam s onset of action was shorter than this study ( 6 )
. this difference may be due to the differences in age distribution of the participants in the 2 studies and the chief complaints on admission . in both studies ,
a relatively significant number of the patients needed additional doses to reach proper sedation and a single dose of the drug had a significant failure rate .
, use of 0.2 mg / kg alone was not enough to induce proper sedation for undergoing ct scan in most children ; it was efficient for only 19% of them ( 2 ) .
regarding onset of action , the results of the present study were in line with those of jevdjic et al . in their 2011 study , especially in the 0.1 mg / kg dose ( 8) .
additionally , regarding probable side effects and effects on vital signs a thorough correlation was seen between the results of this study and rahman study ( 9 ) .
this means that about half the patients need higher doses of midazolam or other drugs such as ketamine to reach the proper level of sedation .
the results of a review study in 2007 showed that despite the similar effects of midazolam and ketamine , ketamine was the drug of choice for both parents and physicians to sedate children ( 10 ) .
therefore , it seems that although midazolam is safe and emergency physicians are familiar with its probable side effects , its success rate , at least with the doses mentioned in the present study , is not high .
therefore , we should either revise the dose of this drug , or use other drugs with higher success probability .
the importance of this matter is that most of the time , when children are not sedated with the initial injection , it makes the parents more anxious and therefore makes the atmosphere more chaotic .
it is suggested to carry out other trials with various doses and bigger sample size , to find the proper dose of drug .
parents not being content about their children participating in the study was among the limitations of the present study , which made case collection somehow difficult .
the results of the present study demonstrated the higher success rate and longer duration of action for 0.3 mg / kg midazolam compared to 0.1 mg / kg .
the groups were equal regarding onset of action , effect on vital signs and probable side effects .
Output:
| introduction : midazolam has turned into a common drug for pediatric procedural sedation and analgesia . however , there is not much data regarding its proper dose and potential side effects in the iranian children population .
therefore , the present study was done to compare 2 doses of iv midazolam in this regard.methods:the present clinical trial was performed to compare 0.1 and 0.3 mg / kg doses of iv midazolam in induction of sedation for head trauma infant patients in need of brain computed tomography ( ct ) scan .
conscious infants under 2 years old , with stable hemodynamics were included .
onset and duration of action as well as probable side effects were compared between the two groups using spss version 22.results : 110 infants with the mean age of 14.0 5.9 months ( range : 4 - 24 ) and mean weight of 9.7 2 kg ( range : 5 - 15 ) were randomly allocated to one of the 2 study groups ( 54.6% female ) .
success rate in 0.1 and 0.3 mg / kg groups were 38.2% ( 21 patients ) and 60% ( 33 patients ) , respectively ( p = 0.018 ) .
overall , 56 ( 50.9% ) patients did not reach proper sedation and were sedated receiving ketamine ( 22 patients ) or another dose of midazolam ( 34 patients , mean additional dose needed was 2.1 1.1 mg).conclusion : the results of the present study demonstrated the higher success rate and longer duration of action for 0.3 mg / kg midazolam compared to 0.1 mg / kg .
the groups were equal regarding onset of action , effect on vital signs and probable side effects . |
PubmedSumm118669 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: the hospital is a place where most undergraduate medical education as well as postgraduate training takes place , so its contribution to the education and training of physicians in general and primary health care trainees in particular merits scrutiny.1 during their postgraduate training , primary health care trainees are exposed to different disciplines such as medicine , pediatrics , obstetric and gynecology and surgery depending on the programme in which they are enrolled whether diploma , fellowship or board .
the quality of training in these disciplines requires continuous evaluation since serious educational deficiencies may interfere with training .
these deficiencies include imbalance between service commitment that should be provided by trainees and the education that he / she needs to receive.1 dissatisfaction with the hospital component of training for primary health care ( general practice ) has been forcefully expressed by many trainees and educationalists in general practice.2 problems that are likely to be encountered during training include shortage of time for teaching , absence of structured programs of learning in each attachment , long duration of some disciplines , denial of study leave , and teaching which is irrelevant to the needs of primary health care physicians.23 the implementation of the primary health care ( phc ) system in the kingdom of saudi arabia ( ksa ) was started in 1984 .
the first program in the kingdom for family and community medicine was started in 1983 in king fahd hospital of the university at al - khobar while in riyadh it started in 1983 with a mater 's degree program and a diploma in 1984 .
the first batch of diplomates graduated in 1986 while the master 's program had its first 6 graduates in 1985 . by the end of 1996 ,
recently , more programs such as the king saud fellowship program in primary health care and the saudi board for primary health care have been established .
the first batch of saudi board trainees graduated in december 1998 . the duration of training for both the diploma and master 's programs are two years , while the fellowship and the board are of 4-years duration .
these years of training are spent in educationally approved disciplines in hospitals as well as in primary care centers .
the major hospital disciplines in these programs are of similar duration while the major differences are in the time spent in the primary health care rotations in phc centers .
training takes place at university , ministry of health or national guard hospitals . in general ,
the educational objectives of these and other rotations are to produce competent family physicians who can provide a wide range of services including promotive , preventive , curative and rehabilitative services to individuals , families , and the community .
to our knowledge , there has been no evaluation of the hospital training component in these programs .
this study was intended to examine the views and satisfaction of phc trainees regarding hospital training in internal medicine and pediatrics .
a cross - sectional study was conducted in january 1996 , in 4 phc training centers : ( 1 ) two centers in riyadh and al - khobar supervised by the university phc departments of family and community medicine ( king saud and king faisal universities , respectively ) , and ( 2 ) two centers in jeddah and al - medina supervised by phc trainers working in these centers .
these centers were selected because they had more than 15 trainees in their programs , and they represented different geographical areas in ksa . besides , these centers started their training programs long before other centers in ksa .
a self - administered questionnaire that included three sections of demographic data , general evaluation of the rotations as well as the evaluation of the contents of the rotations was designed for the survey .
the questionnaire papers were distributed by one of the trainees in all four centers to all the trainees ( n=82 ) in the phc training programs who had finished internal medicine and/or pediatric rotations .
it is worth mentioning that the duration of the rotation of internal medicine varied from 5 to 6 months , while those in pediatrics varied from 3 to 4 months in the different programs .
fifty - one trainees completed the questionnaire giving an overall response rate of 62.2% . of these
chi - square test was used to assess the statistical significance of the different variables .
details of the demographic characteristics of the respondents show that about one - third of them were from the al - khobar center ( table 1 ) ; 75% were males and most of them were married .
their ages ( not included in the table ) ranged from 27 to 40 years and 27.5% were 30 years old .
eleven trainees ( 21.5% ) were trained in other specialties before starting the phc program and only 5 ( 9.8% ) had postgraduate degrees , other than phc .
demographic characteristics of the respondents ( n=51 ) as regards to the overall degree of trainee satisfaction with the rotations , there was greater satisfaction with pediatrics than internal medicine rotations
the overall degree of trainee satisfaction with the rotations on the general evaluation of the rotations ( table 3 ) , the duration of both internal medicine ( 70.6% ) and pediatrics ( 74.5% ) rotations were thought adequate .
however , a feedback on their performance was given only to 64.7% and 68.1% of the trainees during the rotation of internal medicine and pediatrics , respectively .
about 60% of the respondents in both specialties benefited more from the pediatrics on - call duties ( p<0.05 ) .
about 65% of the trainees felt confident in managing medical problems compared to 74.5% for the pediatric problems ( p>0.05 ) .
most of the consultants in both specialties were only partially aware of the concept of phc career and of what was required from the phc trainees . before commencing training in these specialties ,
37.3% and 40.4% of the trainees in internal medicine and pediatrics respectively knew the objectives of the rotations .
however , these objectives were fully achieved by only 35% and 44.1% of the trainees in internal medicine and pediatrics respectively who had identified the objectives .
trainees general evaluation of the rotations half - day release course ( hdrc ) was available to 45.1% and 38.3% of the trainees during internal medicine and pediatric rotations respectively .
evaluation of the content of the training showed that 47.1% of the trainees thought that internal medicine rotation was good and the corresponding figure for pediatrics was 61.7% .
nearly half of the trainees found that the contents of the training were partially relevant to the needs of phc trainees in both rotations .
the balance between work done as a service and the educational sessions was thought to be good by 41.2% and 42.6% of the trainees in internal medicine and pediatric rotations , respectively .
outpatient clinic training was provided for only 60.8% of the trainees during the internal medicine rotation and for 51.1% of the trainees during pediatric rotation .
when the relationship between trainee satisfaction and the content of training was assessed , a statistically significant difference was found in the level of satisfaction during the rotation of internal medicine , between the groups of trainees who perceived the content of training as good and relevant to their needs and those who were not .
trainees who felt that the content of training was good and relevant to their needs were more satisfied than the other group ( p<0.05 ) ( table 4 ) .
the evaluation of pediatric rotation in relation to trainees satisfaction revealed a statistically significant difference in the satisfaction level between the groups of trainees who perceived the duration of the rotation as adequate and those who thought it was not .
the former group was more satisfied than the latter group ( p<0.05 ) ( table 5 ) .
the relationship between trainees satisfaction and some of the contents of training ( medicine ) the relationship between trainees satisfaction and some of the contents of training(pediatrics )
the quality of hospital training for phc doctors should be continuously evaluated to ensure that it fulfills their future career responsibilities .
although the findings in this study were based on a doctor 's subjective recollections of two clinical disciplines , which in some cases had been completed sometime before the study , it highlighted some defects in the training process .
it must be stated that one limitation of this study is that it did not reflect the entirety of the hospital - based training .
interestingly , 21.5% of the trainees had received previous training in other specialties but only 9.8% had postgraduate degrees other than phc , which reflects the ease of entering a residency programme and the lack of regulation to prevent wastage in these programmes .
trainee satisfaction with the rotations showed that they were more satisfied in pediatric rotations than internal medicine rotations , although this difference was not statistically significant .
similar dissatisfaction has also been reported in other previous studies in the uk for which trainees and educationalists suggested that the hospital component of the training should be restructured and the teaching improved.16 the principal complaints of trainees in this study were : ( 1 ) the irrelevance of training to phc trainee needs , ( 2 ) low level of teaching , ( 3 ) imbalance between service work and educational sessions , and ( 4 ) the lack of recognition by the specialists of phc as a career as well as their discernment of its goals and objectives , their grasp of the phc trainee 's needs , with regard to the knowledge and skills to be acquired and attitudes that must be developed .
similar findings have been reported in other studies.1257 overcoming these deficiencies is a major challenge for those involved in postgraduate medical education.2 the factors contributing to these inadequacies may be related to many factors including poor interaction between hospital consultants and phc workers , personal attitudes of some hospital consultants who still regard phc career as inferior , inadequate number of staff in hospital departments , a situation which over burdens phc trainees , the lack of incentives for the teachers , unenthusiastic trainees and the shortage of hospital consultants available for training , as most are attracted to better working conditions outside the training institutes .
however , the fundamental problem may not simply be the lack of organization of the hospital - based training but rather the failure to involve hospital consultants in the planning of the training program .
this has been emphasized by tait8 who suggested that the planning of the training programmes should be done by phc teachers in collaboration with the hospital consultants involved in the training .
trainee satisfaction during the rotation of internal medicine was related significantly to the relevance of training and to the quality of the content of training .
these two points should be considered seriously in planning the medicine rotation , while in pediatrics the only variable which was related significantly to trainee satisfaction was the duration of the rotation , which was thought to be sufficient .
this was in agreement with what was reported in another study,9 in which 75% of the respondents thought that they were looked on as junior doctors rather phc trainees .
the correction of this attitude would go a long way to improving the quality of hospital training and consequently the trainee satisfaction .
it is self - evident that phc doctors need a kind of training which focuses on the skills required to deal most effectively with the problems presented to them by their patients and their community .
this can only be done through the collaboration between designers of the phc training and the hospital consultants .
the trainee 's future role underpins the success of the phc service and should , therefore , not be underestimated .
Output:
| objective : the aim of this study is to assess the perception and satisfaction of primary health care ( phc ) trainees regarding their hospital training in internal medicine and pediatrics.methodology:a cross - sectional study was conducted by means of a self - administered questionnaire distributed to the trainees who had finished medicine and/or pediatrics rotation in 4 phc training centers in riyadh , al - khobar , jeddah and al - medina during january 1996.results:trainees were more satisfied with the pediatric rotation than the internal medicine rotation . significant relationship ( p<0.05 )
was found between trainee satisfaction in internal medicine rotation and both the quality of training and the relevance of training to the needs of phc trainees . on the other hand , in pediatrics ,
the only variable which was related significantly to the trainees satisfaction was the duration of the rotation , which was found to be sufficient ( p<0.05 ) .
trainees dissatisfaction with the rotation was due to many factors , such as the imbalance between service work and educational sessions and the lack of awareness of other specialists about phc as a career.conclusion:attention and effort should be directed towards the improvement of hospital training through a close collaboration between the decision - makers for phc training and the hospital consultants .
also the needs of trainees should be taken into account during planning of hospital training . |
PubmedSumm118670 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: prostate cancer ( cap ) is the most common nonskin cancer and the second or third leading cause of death from cancer among men in the developed world . in the uk ,
more than 36,000 men are diagnosed with cap each year , comprising a quarter of all cancers diagnosed in men .
although approximately 10,000 men died from cap in the uk in 2008 , survival rates for cap patients have changed markedly over the past 40 years .
more than 75% of cap patients currently survive beyond five years , compared with less than a third of the patients with five - year survival in the 1970s ; the differential is even greater in the ten - year survival experiences now compared to 40 years ago
moreover , in this large group , the burden of disease from cap is preponderantl in elderly men , with men who are 70 years or older comprising more than half the patient population in the uk .
consequently , cap patients often present for medical care with advanced age - related comorbidities . the number and types of patient comorbidities have informed treatment choice for cap in clinical practice , with less aggressive treatment used as comorbidity increases [ 49 ] .
comorbidity scores have been shown to predict outcomes ranging from late urinary complications to overall survival among men who have undergone radical prostatectomy . moreover ,
specific comorbidities , or a high number of comorbidities , have been used in some instances to exclude patients from clinical trials due to concerns of increased risk of adverse events .
therefore , a thorough understanding of the occurrence of comorbidities in cap patients in a real - world setting has important implications for drug development , clinical practice , and patient management . while there has been excellent work to date documenting the impact of comorbidities on treatment decisions among men with cap , these studies have some limitations from the perspective of clinical development of novel treatment or preventive medicines .
many studies examined the existence of the comorbidity only at the time of initial cap diagnosis .
there is sparse information that describes comorbid illnesses that arise during the treatment phase of the disease .
moreover , several studies restricted comorbid information to scores for the intent of profiling the overall risk of each patient , rather than examining specific comorbidities . additionally , only one study reported to date has compared cap patients to an age - similar non - cap group .
quantification of specific concomitant diseases during a prevention or treatment period in a population of patients that closely mirror users of novel therapies and putting these rates in context with rates from age - similar populations is useful .
therefore , to complement the body of information from previous studies , we conducted a longitudinal cohort study in the general practice research database ( gprd ) among men with cap and compared specific comorbidities and medications among these men to an age- , practice- , and length of followup - matched set of controls .
in addition to prevalence of comorbidities at the time of initial cancer diagnosis , we examined the incidence of major comorbidities during a follow - up period of approximately four years and overall survival for the entire observation period in both cases and controls .
we further defined a cohort of men at risk for cap , demonstrated by 2 or more elevations in psa level within 12 months , but without cap , and matched this high - risk group to a noncancer , non - psa - elevated control population to explore background prevalence , incidence , and medication use rates as a framework for better understanding patients in one of our major on - going clinical development programs .
the objective of this study was to compare the prevalence and incidence of comorbidities and concomitant medication use and overall survival in patients with cap and in men at risk of cap , defined as having prostate - specific antigen ( psa ) levels > 2.5 ng / ml but without cap , to men of the same age without cap and no elevated psa . comorbidities or newly occurring events of specific interest included urinary tract infections ( uti ) , impotence , breast disorders , hypertension , acute coronary syndrome , myocardial infarction , angina pectoris , stroke , congestive heart failure , cardiac arrhythmias , lower extremity arterial occlusive disease , type ii diabetes , and hyperlipidemia , conditions selected for their relevance to the age group and to reported events among men with or at risk of cap .
the study was a retrospective longitudinal comparative cohort study of men in the gprd , comprising data from august 1 , 1998 to july 31 , 2008 .
data are drawn from the computer systems used by general practitioners ( gps ) to maintain clinical records within their practices and contain all primary care records deemed relevant to patient care .
data quality is monitored continuously by the uk medicines and healthcare products regulatory agency ( mhra ) , and practices that fail to maintain the required standards are removed from the database .
currently , data are collected from 613 general practices throughout the uk , providing information from 9.7 million patients with records in the system at any time point and 4.5 million currently registered patients .
mean follow - up is 6.6 years ( median , 5.0 years ) for currently registered patients . among men 18 years of age in the gprd , we identified two cohorts of men , referred to as
cases : men with a diagnostic code of cap who had no record of cancers other than cap and nonmelanoma skin cancer and men with at least two elevated psa results , defined as psa > 2.5 ng / ml , but no diagnosis of cap . given that there is a continuum of cap risk at all values of psa and no cutpoint of psa with simultaneous high sensitivity and high specificity for identifying cap , psa > 2.5
ng / ml was selected to be consistent with the inclusion criteria in a major on - going clinical trial .
a man with elevated psa who went on to have cap was included only in the cap group .
the date of the first cap diagnosis was the index date for each cap patient , and the date when the first elevated psa result was recorded was the index date for each man with elevated psa but no cap .
a second elevated psa result must have been recorded within 12 months after the index date to ensure a true positive result , as patients may have had a false positive reading or may have had elevated levels due to acute urinary tract infection . for each case , a control was selected among those who had no diagnostic codes for cap , no benign prostate conditions , that is , benign prostatic hyperplasia ( bph ) and/or prostatitis , and no elevated psa result , but had at least one psa measurement throughout the 10-year observation period .
cases could , however , have a diagnosis of prostatitis or bph at any time .
cases and controls were matched on age ( 1 year when possible , up to 5 years allowed ) , region of practice , length of follow - up , and observation period ( either august 1 , 1998 to july 31 , 2003 or august 1 , 2003 to july 31 , 2008 ) .
matching on region of practice was to ensure similar socioeconomic factors , such as income and access to health insurance or scored utilization of primary health care , between cases and controls .
the index date for each control was the same as the index date of his matched case .
we included only those men that had at least 12-month history in the gprd prior to the index date in order to adequately assess prior occurrences of disease or event of interest .
men must have had at least 3 months of follow - up postindex date to be included in the postindex date analysis of prevalent comorbidities and medications .
no minimum follow - up was required for analysis of incident comorbidities and medications , which allowed inclusion of less healthy ( e.g. , near terminal ) cap patients , resulting in a more generalizable cap population . for medication use
, we restricted our population to the subgroup of men with index dates between august 1 , 2003 and july 31 , 2008 , in order to provide a more up - to - date pattern for medication use .
baseline characteristics included age at the index date , region of practice ( defined as eastern , southern , northern london , and others ) , smoking status ( defined as never , current , and past ) , and psa levels .
psa levels were categorized as 2.5 , 2.5110 , and > 10 ng / ml .
they were also categorized by the age - dependent uk cutoff values of 3.0 ng / ml for men aged 5059 years , 4.0 ng / ml for men aged 6069 years , and > 5.0 ng / ml for men aged 70 years and over , as recommended by the prostate cancer risk management programme .
diseases and events of specific interest included uti , impotence , breast disorders , hypertension , acute coronary syndrome , myocardial infarction , angina pectoris , stroke , congestive heart failure , cardiac arrhythmias , lower extremity arterial occlusive disease , type ii diabetes , and hyperlipidemia and were defined according to the read and oxmis codes .
general comorbidities were examined among the entire cohort of men , listed by the meddra high - level terms .
medications were assessed among a subgroup of men in gprd within the latter five years ( i.e. , index dates between august 1 , 2003 and july 31 , 2008 ) , listed by class per british national formulary ( bnf ) header within the product files .
patient mortality status ( yes / no ) was used for calculating the all - cause mortality rates .
causes of death were obtained for approximately 60% of patients in gprd , those who had consented to the linkage to the office for national statistics ( ons ) death data .
the underlying causes of death were recorded and described according to the international statistical classification of diseases and related health problems 10th revision ( icd-10 ) .
frequencies of more than 2% for individual events and of more than 3% for systems of diseases were reported .
we compared baseline characteristics in the two case groups that were successfully control matched to the cases we were unable to match .
within each matched set , we compared baseline characteristics of each case group to its respective control group .
for comorbidities of special interest , we examined the prevalence during the 12 months prior to the index date and the cumulative incidence for the entire follow - up period .
cumulative incidence analysis was conducted among the at - risk population comprising only men who did not have a documented specific comorbid event during the 12-month period prior to the index date .
men who left the gprd data system during follow - up due to sustained inactivity ( no record of any diagnosis or medication during 12 months ) , known transfer out of the system , or death were included in the at - risk denominator .
we evaluated the incidence rates , in person - years ( py ) , at 12 and 48 months of follow - up , and explored the trend between the two periods .
the incidence rate calculation accounts for varying degrees of follow - up , with py calculated as the time interval between the index date and either the date of the event , the date when they became inactive , the date they were transferred out of the gprd system , the date of death , or july 31 , 2008 , whichever came first . for capturing the most frequently occurring comorbidities and concomitant medication use , we examined the prevalence over the 12 months prior to the index date ( pre - period ) as well as 12 months after the index date ( post - period ) .
we compared the prevalence among cases versus controls within each period and then the prevalence during the pre - period versus the post - period within each group .
kaplan - meier survival curves were plotted , and all - cause mortality rates were estimated for men with cap , men with elevated psa but no cap , and their matched controls over the 10-year period .
all analyses were conducted using sas version 9.1.3 , with a significance level of = 0.05 . for each comorbidity and concomitant medication , the significance of the prevalence or cumulative incidence comparison between cases and controls was tested by a two - sided fisher 's exact test of the null hypothesis odds ratio , or = 1 ( i.e. , odds in cases = odds in controls ) . for incidence rate or mortality rate comparisons ,
a two - sided significance test was performed on the null hypothesis rate ratio , rr = 1 ( i.e. , rate in cases = rate in controls ) .
this was based on the assumption that the counts have poisson distributions , so that the distribution of log(rr ) is approximately normal , a valid assumption provided that case and control counts are fairly large ( > 30 ) .
the formula for the variance of a log(rr ) given , for example , by agresti ( p. 71 ) can then be adapted to obtain var(log(rr ) ) = 1/n1 + 1/n2 , where n1 = count in cases and n2 = count in controls .
the estimate of log(rr ) and its variance are then used to perform a z test of the null hypothesis .
neither test takes account of the pairing of cases and controls and is therefore conservative .
in the gprd , 3,036 cap patients and 11,339 men with elevated psa but no cap were identified . of these , matching was successful for 86% of the cap patients and 89% of those with elevated psa but no cap .
unmatched cases ( 420 cap patients and 1,211 men with elevated psa but no cap ) were older than the matched cases ( median age 81 years versus 68 or 72 years , resp . ) and had a greater proportion with psa of > 10 mg / ml ( 35% versus 20% , resp . ) .
cap patients were slightly older than men with elevated psa but no cap , with median ages of 72 and 68 years , respectively ( table 1 ) . in both case groups ,
nearly half of the men were nonsmokers and 1316% were current smokers . among men with elevated psa but no cap , 19.7% had psa levels over 10 ng / ml ; using age - specific uk cutoff values , as per national health service guidance , only 75% of these men would have been classified as having elevated psa . during the 12 months
prior to the index date , 28% of the cap patients had bph and 2% had prostatitis . among men with elevated psa but no cap , 13% had bph and 0.8% had prostatitis ( data not shown ) .
men had a 3- to 5-fold higher prevalence of utis and somewhat higher prevalence of impotence compared with controls ( table 2 ) .
men with elevated psa but no cap had a lower prevalence of diabetes than their controls .
the cumulative incidence of uti was also significantly higher , and the cumulative incidence of stroke was lower in each case group compared to their matched controls ( table 3 ) . compared with controls ,
cap patients also had higher cumulative incidence of impotence and breast disorder and lower cumulative incidence of hyperlipidemia .
men with elevated psa but no cap had lower cumulative incidence of congestive heart failure .
no differences between cases and controls were observed for hypertension , acute coronary syndrome , angina pectoris , myocardial infarction , type ii diabetes , and lower extremity arterial disease .
incidence rates per 10,000 person - years , which account for varying follow - up time , demonstrated statistically significant differences between cap cases and controls for the outcomes of uti , impotence , and breast disorder .
specifically , cap patients had a nearly 5-fold higher incidence rate ( ir ) of uti , a 3.5-fold higher ir of impotence , and a 7-fold higher ir of breast disorders , at 12 months compared with controls ( table 4 ) .
the irs of uti and impotence over time were stable among controls but declined among cap patients .
for instance , the irs of uti , among cap patients , were 867 per 10,000 person - years [ py ] , which was almost 5-fold higher than controls , during the first 12-month period , and 552 per 10,000 py , which was 3.5-fold higher than controls , during the 48-month period after diagnosis .
the irs of breast disorders changed little over time among both cap patients and controls .
cap patients had 40% lower ir of stroke at 12 months and 30% to 40% higher ir of hypertension and congestive heart failure at 48 months only .
men with elevated psa but no cap also had a higher ir of uti ( over 5-fold for the first 12-month period and 2.8-fold for the 48-month period ) and slightly higher ir of hypertension , compared with controls ( table 4 ) . irs of impotence and breast disorders were similar between cases and controls .
men with elevated psa experienced a 40% higher rate of type ii diabetes and a 60% lower rate of lower - extremity arterial occlusive disease during the first 12-month period after the first elevated psa test result .
no other outcomes differed substantially between elevated psa / no cap cases and their controls . across all four groups ,
cardiovascular - related issues were the most common comorbidity among men of this age ( data not shown ) .
cap patients had higher prevalence of urinary tract signs and symptoms than matched controls ; the prevalence was 43% during the 12-month period prior to cap diagnosis then dropped to 19% during the 12-month period after cap diagnosis and was 7% and 8% among controls in the 12-month period before and after the index date , respectively ( figure 1 ) .
men with elevated psa also had higher prevalence of urinary tract signs and symptoms ( 29% and 31% during the 12-month period before and after the elevated psa results , resp . ) , compared with controls ( 6% to7% across both periods ) .
medication use was examined in the subgroup of men in gprd from 2003 to 2008 . during both the 12-month period before and the 12-month period after the index date , the most commonly used medications among men across the four cohorts included nonopioid analgesics and nonsteroidal anti - inflammatory drugs ( nsaids , 40% to 50% ) , statins and antiplatelet drugs ( 27% to 37% ) , opioid analgesics , angiotensin - converting enzyme inhibitors , beta - adrenoceptor blocking drugs , and calcium channel blockers ( 20% to 30% , data not shown ) .
table 5 highlighted the prevalence of concomitant medication use that was statistically significantly different between cap patients and their controls or between men with elevated psa but no cap and their controls .
uses of alpha blockers in urinary retention , alpha adrenoceptor blocking drugs , sulphonamides and trimethoprim , and quinolones were 2- to 4-fold more common for cap patients before and after index date , compared to matched controls . for men with elevated psa compared to controls , use of these same medications was 2- to 4-fold more common for cases than controls before index date and 3- to 5-fold more common after index date .
after diagnosis , use of lidocaine / lignocaine in anaesthesia was 10-fold higher in cap patients than controls , compared to only 2-fold higher prediagnosis .
prostate cancer drugs and gonadorelin analogues , drugs affecting gonadotrophins , male sex hormones , and antagonists were commonly used among cap patients , especially after cancer diagnosis .
more men with elevated psa but no cap were on alpha - blockers in urinary retention , alpha - adrenoceptor blocking drugs , male sex hormones and antagonists , and statins during the 12-month period after ( versus before ) the index date .
cap patients had the poorest survival , with a 2.6-fold higher all - cause mortality compared to their matched controls ( figure 2 ) .
controls matched to cap patients had slightly higher all - cause mortality than controls matched to men with elevated psa , likely due to their older age . in contrast , all - cause mortality was slightly lower among men with elevated psa compared to their matched controls .
of the 2,075 deaths in these four cohorts , we were able to link electronic medical data to death certificates for 1,226 ( 59% ) patients .
table 6 presents the underlying causes of death among men who died within each group .
frequencies of more than 2% for individual event types and of more than 3% for systems of diseases were reported . among cap patients ,
nearly 60% ( n = 220 ) of the deaths were ascribed to neoplasms , and 58% ( n = 213 ) to cap .
in contrast , 12 men with elevated psa died of cap ( i.e. , 4.6% of 197 deaths ) , and no men died of cap among controls .
next to neoplasms as an underlying cause , 25% of the deaths among cap patients were ascribed to diseases of the circulatory system compared to men with elevated psa and no cap ( 46% ) and men in the two control groups ( 52% and 49% ) .
the percentage of deaths due to other underlying causes , such as respiratory and nervous systems , was lower among cap patients compared to the other three groups of men . among men with elevated psa with no cap and men in the two control groups ,
46% to 51% of the deaths were due to diseases of circulatory system , as mentioned above , 17% to 21% due to diseases of respiratory systems , and 8% to 13% due to neoplasms .
this study examined the prevalence and incidence of comorbidities and the prevalence of concomitant medication use among men with cap , men deemed at increased risk of cap due to elevated psa , and control groups that were matched to these men on age , practice , and duration and calendar period of follow - up in the gprd .
we included men with elevated psa identified between august 1 , 1998 and july 31 , 2008 and found that a fairly high proportion ( ~20% ) of these men had psa levels over 10 ng / ml but had never been diagnosed with cap .
although this observation seems inconsistent with the high specificity of the psa test at the level of > 10 ng / ml , it may reflect the reality in uk . according to the uk prostate cancer risk management programme
, cap screening was not offered for asymptomatic men during this time period , given that the extent of benefit and harm of such screening are still under debate [ 1820 ] . men with elevated psa may or may not be further evaluated for cap , due to the lack of agreement among primary care physicians regarding what psa cutoffs should trigger patient referrals [ 21 , 22 ] . compared with controls , cap patients had significantly higher incidence of uti ( 2- to 5-fold ) , impotence ( 2- to 3-fold ) , and breast disorders ( 3- to 7-fold ) after diagnosis , which is consistent with earlier studies [ 23 , 24 ] .
men with elevated psa also had higher incidence ( 3- to 5-fold ) of uti , compared with controls . for several conditions , including uti and impotence among cap patients and uti , hypertension , and diabetes among men with elevated psa but no cap , the incidence was the highest , and the differences between cases and controls were the greatest during the first 12 months of follow - up ; rates were lower and differences were smaller at 48 months of follow - up . a plausible explanation may be that previously undiagnosed conditions are coming to medical attention after cap diagnoses or the elevated psa findings due to more intense medical scrutiny .
the prevalence and incidence of hypertension and cardiovascular - related comorbidities , including acute coronary syndrome , angina pectoris , arrhythmia , myocardial infarction , congestive heart failure , and lower extremity arterial occlusive disease , were generally similar between cap patients , men with elevated psa , and controls .
the prevalence of hypertension prior to the index date ( 5 - 6% ) was lower than in most population - based studies among older men or cap patients [ 2529 ] .
however , comparing our results to the existing body of literature is particularly difficult , given the differences in study populations , study design , and outcome definitions
. moreover , many studies presented the prevalence data over multiple years , whereas in this study , we examined the prevalence during a 12-month period prior to cap diagnosis or first elevated psa result , and incidence after the index date .
when we examined the most frequently occurring comorbidities , the prevalence of urinary tract signs and symptoms remained similar over time for men with elevated psa ( ~30% ) , despite an increase in alpha blocker use from 17% during the 12 months prior to the elevated psa results to 32% during the 12 months after the elevated psa results .
for men with cap , the prevalence of urinary tract signs and symptoms was high ( 43% ) during the prediagnostic period and dropped to 19% after diagnosis , likely attributable to cancer treatment .
consistent with the study design that controls must not have cap , elevated psa , and/or any benign prostatic diseases , the prevalence of urinary tract signs and symptoms and alphablocker use were low at 68% over time among controls .
several medications , including nsaids , nonopioid analgesics , antiplatelet drugs , statins , ace inhibitors , and/or calcium channel blockers , were commonly used by these men , similarly across all four groups .
these results may serve as the background information for better understanding drug - drug interactions during clinical development .
this study showed that , in contrast to cap patients , who had over 2-fold higher all - cause mortality rate than their matched controls , men with elevated psa but no cap had a slightly lower mortality rate than their matched controls .
this may be explained by the relatively low psa threshold value we used to define an elevation in psa level .
it may also be a reflection of the complexity of cap screening using psa measurements and the subsequent effect on cap mortality , demonstrated in several large randomized studies to be controversial [ 18 , 20 , 30 ] .
the cause of death analysis was conducted among patients who consented to the linkage between gprd and death certificates . among cap
diseases of circulatory and respiratory systems were important competing risks for cap patients and were typical causes of death for all groups of men .
cap patients and men with elevated psa who could not be matched to controls were slightly older than matched cases . excluding unmatched cases from the analysis
could have introduced bias if they differed systematically from those who were matched . however , other baseline demographic factors including smoking status and region of practice were similar between matched and unmatched cases , arguing against substantial bias from this source . excluding men with bph and/or prostatitis from the controls
could have magnified case - control differences for comorbidities or medications that are correlated with bph or prostatitis .
the gprd is a primary care database and relies on accurate upload of data from the member practices .
data transfer from hospitals to the gprd can be delayed or missing if gps do not code and enter the information when they receive it from the hospital .
we were unable to explore prevalence and incidence of comorbidities and comedication use by cancer stage and gleason score because the gprd lacks these important details .
the profile of advanced cap patients and early - stage disease patients may well differ with respect to comorbidities and especially medication use , given the indolent nature of the cancer . despite these limitations , this study has several strengths . as previously shown , the gprd provides a representative description of patients within the uk .
it is a suitable data source for this study , as it is proficient at recording comorbidities and medical care conducted by the gp in primary care .
furthermore , gprd is an appropriate database especially for studying men with elevated psa . per national institute for health and clinical excellence ( nice ) guidance
, men with elevated psa are identified initially in primary care and receive a second test by the gp within 3 months after the initial elevated psa result .
patients then are referred to a specialist , if the psa level is elevated again .
if cap is not diagnosed , patients will return to the care of the gp and be followed within primary care .
this study provides population - based estimates on the occurrence of comorbidities and medication use among cap patients and men with elevated psa but no cap .
compared with age- , region- and practice - matched controls who had no cap nor elevated psa , cap patients had a higher incidence of urinary tract infection , impotence and breast disorder , and a 2.6-fold higher risk of all - cause mortality .
fewer differences in comorbidities and medication use were noted when men with elevated psa but no cap were compared to matched men without elevated psa nor cap than were seen between cap patients and their matched controls .
the mortality rates were slightly lower for men with elevated psa but no cap than for matched controls .
cardiovascular events were similar between cap patients and their controls and between men with elevated psa but no cap and their controls . at the time of diagnosis of cap or the first occurrence of elevated psa , many of the most prevalent comorbidities and medications were consistent across groups and are typical of an older male population .
as the presence of comorbid conditions and medications places older patients at greater risk of adverse effects from certain interventions , and comorbidity may influence screening practice , treatment choice , quality of life , and survival , these data in the real - world setting are broadly applicable throughout the drug development cycle and subsequent patient management .
Output:
| comorbidity influences screening practice , treatment choice , quality of life , and survival .
the presence of comorbidities and medication use could place patients at greater risks of adverse effects from certain interventions .
we conducted a longitudinal cohort study in the general practice research database to better understand comorbidities and medication use in men with or at risk of prostate cancer ( cap ) . compared with men with similar age but no cap , cap patients had higher incidence of urinary tract infection , impotence and breast disorder , and 2.6-fold higher all - cause mortality . among men with elevated prostate - specific antigen ( psa ) but no cap ,
the mortality rates were slightly lower , and fewer differences in comorbidities and medication use were noted compared to men without elevated psa .
many prevalent comorbidities and medications were consistent across groups and are typical of an older male population .
these real - world data are broadly applicable throughout the drug development cycle and subsequent patient management . |
PubmedSumm118671 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: abdominal hernias are a common cause of bowel obstruction . the major types of abdominal hernias are external or abdominal wall hernias , which occur at areas of congenital or acquired weakness in the abdominal wall.1 thus , the occasional link between such pathologies and peritoneal dialysis ( pd ) , which is associated with increased intra - abdominal pressure,2 may not be surprising.3 a different entity is internal hernias , which are characterized by a protrusion of the viscera through the peritoneum or mesentery4 and have been shown to account for approximately 0.55.8% of all cases of intestinal obstruction.4,5 in this report , we describe our experience with a pd patient who was diagnosed with a bowel obstruction due to intestinal herniation , which occurred as a result of a defect of the broad ligament of the uterus .
a 65-year - old woman who was treated with continuous ambulatory pd ( capd ) was admitted with lower abdominal pain of 1-day duration , which was followed by intermittent nausea and vomiting .
she had chronic renal failure due to chronic glomerulonephritis , and had been treated for 22 months with capd ( four daily exchanges ; 2 l of midperiq 135 4 ; terumo co. ) .
a tenckhoff catheter was implanted through a classic transverse surgical incision , with a favorable postoperative course .
her other medical history included hypertension , and she had undergone total hysterectomy because of a uterine myoma 15 years previously . a physical examination conducted on admission revealed that she was alert and oriented , and had a body temperature of 36.6 c .
a clinical examination disclosed diffuse tenderness without peritoneal signs , while the abdomen was slightly distended and tympanic with diminished bowel sounds .
the peritoneal fluid was clear , with a white blood cell ( wbc ) count of less than 50/mm .
the skin surrounding the peritoneal catheter , as well as the catheter s exit site , was unremarkable without any signs of inflammation .
a laboratory evaluation revealed the following findings : wbc , 6300/mm ; hemoglobin , 8.0 g / dl ; hematocrit , 22.7% ; platelet count , 28.5 10/mm ; blood urea nitrogen , 43 mg / dl ; serum creatinine , 6.5 mg / dl ; sodium , 137 mmol / l ; potassium , 4.3 mmol / l ; chloride , 104 mmol / l ; and c - reactive protein , 0.44 mg / dl .
upright radiography showed some loops of dilated bowel with air - fluid levels ( fig .
1 ) . initially , a small bowel obstruction due to post - hysterectomy - related adhesion was suspected and she was managed conservatively . however , computed tomography ( ct ) of the abdomen , which was performed 2 days after admission , demonstrated discontinuity of the small bowel with a distended closed loop in the pelvic cavity ( fig .
2 ) , suggesting that strangulation was the likely cause of the development of the bowel obstruction .
she was therefore subjected to an exploratory laparotomy , which revealed incarcerated , small bowel herniation into the pouch of douglas through a defect of the residual broad ligament of the uterus ( fig .
3b ) ; however , it was not ischemic and the entrapped bowel was freed using a bowel forceps , while the defect of the broad ligament was closed ( fig .
the pd catheter was also removed because the patient refused to continue with the pd .
she started to receive hemodialysis ( hd ) three times per week via a right internal jugular vein catheter on the day after the operation .
finally , a wrist - arterio - venous fistula was created to provide permanent vascular access , and the periodic hd program was continued .
the majority of cases occur secondary to adhesion from prior surgery.6 the remaining cases may be due to neoplasms , abdominal wall hernias , and , in decreasing frequency , crohn s disease , volvulus , intussusception , bezoars , gallstones , trauma , and iatrogenic problems.79 bowel obstruction is rarely attributed to internal hernias.4,5,79 broad ligament hernias are extremely rare and account for only a few percent of internal hernia cases.4 in this regard , the paucity of literature describing the complications of internal hernias in patients who receive pd may not be surprising . to the best of our knowledge ,
this is the first report of a long - term pd patient with internal herniation that occurred because of a defect of the broad ligament of the uterus .
the broad ligaments of the uterus consist of layers of peritoneum that cover the intestinal and vesical surfaces , which are carried laterally in a tripod fashion to the side walls of the pelvis.10 based on the nature of the defects , the hernias can be classified into two categories : the fenestra type , with defects in both peritoneal layers , and the pouch type , with defects in only one of the two layers.4,11 as seen in the current patient , the viscera may be allowed to pass through the defect with potential hernial strangulation in subjects with fenestra - type hernias ; otherwise , such structures may be permitted to enter and become entrapped in the parametrium in patients with pouch - type hernias.4 the most common herniating viscus is the small intestine ; less common structures include the sigmoid colon , ovaries , cecum , omentum , appendix , and the ureter.10 the youngest patient ever described was 16 years of age,12 while more than 85% of the cases have occurred in parous women.10 a defect of the broad ligament is often present in a unilateral portion , and several etiological factors for such defects have been suggested , including trauma during pregnancy or delivery , surgical injury , pelvic inflammatory disease , and congenital anomalies.4,1014 in the current case , the etiology of the disease could be multifactorial since our patient had a history of pregnancy , delivery , and abdominal surgery .
although it is difficult to determine the precise contributions of each factor , we believe that the patient s previous hysterectomy likely played a major role in the formation of the defect in the residual broad ligament .
the tractive and/or stretching nature of pd , which is characterized by increased intra - abdominal pressure due to retention of dialysate , may have played an additional role in exacerbating the ligament fenestration , thereby predisposing our patient to the disease .
hernias of the broad ligament have often been discovered at laparotomy for other reasons , and unless the defect is suspected after previous uteropexy the precise preoperative diagnosis of the disease is quite uncommon.10,15 this was also the case in the current patient . indeed , a combination of the patient s medical history , which included a hysterectomy and an abdominal x - ray that showed the dilated loops of the bowel , encouraged us to initially attribute the illness to postoperative adhesion .
plain film radiography does not help with the specific diagnosis because of its low sensitivity and specificity.16 barium enema or other radiologic modalities , including ct , may occasionally lead to a correct diagnosis.10,17,18 the workup with the imaging analyses was not sufficient to allow a preoperative diagnosis of broad ligament herniation ; however , the persistent ileus with the closed - loop obstruction , a ct finding that is suggestive of bowel strangulation,9 led us to perform prompt surgical treatment , which likely played a pivotal role in avoiding bowel ischemia , necrosis , and perforation , which would have required intestinal resection and resulted in various degrees of complication.10,19,20 abdominal wall hernias , localized pd catheter - related adhesions , and sclerosing encapsulating peritonitis , all of which may require prompt surgical intervention , are regarded as disease - specific causes of small bowel obstruction in patients with pd.2126 we believe that broad ligament herniation should always be regarded as the potential cause for the disease as well , especially in female patients who receive pd .
this would lead to a high index of suspicion , prompt recognition , and immediate intervention , which are essential for reducing or preventing major morbidities of the disease.27 considering the fact that our patient did not require bowel resection , it might have been possible for her to resume pd at an intermittent schedule using low - volume dialysates despite the concerns about the leakage of dialysate and dehiscence because of poor wound healing mediated by abdominal distension.2,2832 finally , there are no clear recommendations regarding either the interruption or withdrawal of pd after abdominal surgery,20,31,32 and we gave priority to the patient s decision .
the optimal therapeutic strategy for internal herniation in patients who receive pd may only be determined with the accumulation of experience from a larger number of cases similar to ours .
Output:
| abdominal hernias are a common cause of bowel obstruction . the major types of abdominal hernias are external or abdominal wall hernias , which occur at areas of congenital or acquired weakness in the abdominal wall . an alternative entity is internal hernias , which are characterized by a protrusion of viscera through the peritoneum or mesentery .
we herein present the case of a female peritoneal dialysis patient with bowel obstruction due to an internal hernia .
although an initial work - up did not lead to a correct diagnosis , an exploratory laparotomy revealed that she had intestinal herniation due to a defect in the broad ligament of the uterus , which was promptly corrected by surgery .
the concerns about the perioperative dialytic management as well as the diagnostic problems regarding the disease that arose in our experience with the present patient are also discussed . |
PubmedSumm118672 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: type 1 diabetes mellitus ( t1 dm ) is an autoimmune disease caused by t cell - mediated destruction of pancreatic cells resulting in the absence of insulin and uncontrolled hyperglycemia .
a complex interplay between genetic and environmental factors participates in developing of t1 dm and manifestation of its systemic and oral complications .
periodontitis has been identified as the sixth complication of diabetes ; the other five complications are retinopathy ( dr ) , nephropathy ( dn ) , neuropathy ( dpn ) , macrovascular disease , and poor wound healing .
periodontitis is a chronic infection characterized by progressive inflammatory response to bacteria in dental plaque , which finally results in periodontal tissue destruction and tooth loss .
chronic hyperglycemia induces a proinflammatory state in the gingival microcirculation characterized by an increased vascular permeability , and leukocyte and endothelial cell activation , which may contribute to periodontal tissue damage in diabetes mellitus .
chronic periodontitis ( cp ) is more frequent in t1 dm patients and can worsen its metabolic control [ 4 , 5 ] .
nevertheless , molecular mechanisms responsible for periodontal disease and its progression in t1 dm patients remain unknown .
although individuals at risk for t1 dm are recognized by screening for hla - associated risk genotypes and cell autoantibodies , recently the pathogenic role of il-17-secreting t helper 17 ( th17 ) cells has been implicated in the development of t1 dm [ 68 ] .
the il-17 cytokine family consists of six cytokine members designed from il-17a ( originally cloned and named ctla-8 ) , il-17b , il-17c , il-17d , il-17e , and il-17f , according to the order of their discoveries . il-17a and il-17f , the most studied members in the il-17 family ,
are located close to each other on human chromosome 6 , sharing the highest amino acid sequence identity ( 50% ) and similar functions .
they are primarily involved in autoimmune responses , tumor development , and host defense against bacterial and fungal infections by activating epithelial innate immune responses and production of antimicrobial peptides , cytokines ( e.g. , il-6 or tnf- ) , chemokines ( e.g. , il-8 ) , and cartilage degrading metalloproteinases as well as cytokines promoting osteoclastogenesis that results in bone destruction [ 911 ] .
bradshaw et al . observed that monocytes isolated from t1 dm patients induced more il-17 producing t cells compared with healthy controls .
they also observed significantly increased il-17 producing t cells in peripheral blood of patients with long standing t1 dm .
arif et al . demonstrated that activation of il-17 pathway accelerated pancreatic cell apoptosis and led to autoimmune diabetes .
in addition , peripheral blood lymphocytes from t1 dm patients had elevated il-17a and il-17f expression .
the emerging role of il-17 in periodontal disease was also discussed in a recent study , based on evidence from human and animal models .
upregulated il-17a gene expression has been observed in patients with cp , suggesting that the net effect of il-17 signaling promotes the disease development [ 1622 ] .
additionally , il-17ra deficient mice were found more susceptible to porphyromonas gingivalis ( p.g . ) , causal gram - negative bacteria of the red complex [ 23 , 24 ] .
based on the fact that increased il-17 levels occur in the gingival tissue of patients with periodontal disease [ 2527 ] , park et al .
lipopolysaccharide ( lps ) might mediate il-17 release from human periodontal ligament cells . despite the important role of il-17 cytokine in t1 dm and cp pathogenesis
, no study has investigated il-17 gene variability in t1 dm patients so far and only a few studies have reported a relationship between polymorphisms in the il-17 gene and periodontitis with contradictory results [ 2933 ] .
therefore , in the present study , we aimed to investigate the association of il-17a 197a / g ( rs2275913 ) and il-17f + 7488c / t ( his161arg , rs763780 ) gene polymorphisms with t1 dm and/or cp .
in addition , il-17a single nucleotide polymorphism ( snp ) was examined in relation to the occurrence of selected periodontal bacteria in subgingival pockets and production of il-17 by mononuclear cells in a subgroup of cp patients and healthy controls .
the study was performed with the approval of the committees for ethics of the medical faculty , masaryk university brno and st .
written informed consent was obtained from all participants in line with the helsinki declaration before inclusion in the study . in this case - control study
one hundred and twenty - five patients with t1 dm were followed in the outpatient unit of the diabetology clinics in south moravia region , czech republic .
the diagnosis of t1 dm was originally based on the presence of clinical symptoms ( such as polyuria , polydipsia , and weight loss ) and biochemical parameters ( glycemia , ketoacidosis , and autoantibody status ) .
all patients were receiving intensified insulin therapy or insulin pump and other medicaments according to the presence of diabetic complications , such as dn , dr , dpn , and other comorbidities as described on a part of our cohort previously .
duration of diabetes was defined as the period from diabetes onset until the enrolment in this study .
levels of glycemia , glycated hemoglobin ( hba1c ) , total cholesterol , triglycerides , high density lipoprotein ( hdl ) , low density lipoprotein ( ldl ) , body mass index ( bmi ) , and further parameters were recorded .
the periodontal status was evaluated in a subgroup of 38 diabetic patients , 154 healthy controls , and 244 cp subjects recruited from a patient pool of the clinic of stomatology , st .
the controls were selected from subjects referred to the clinic of stomatology for reasons other than periodontal disease ( such as dental caries , orthodontic consultations , and preventive dental checkups ) during the same period as patients and matched for age and gender .
exclusion criteria were history of systemic diseases such as cardiovascular disorders ( e.g. , coronary artery diseases ) , diabetes mellitus , malignant diseases , immunodeficiency , and current pregnancy or lactation .
the diagnosis of periodontitis / nonperiodontitis was based on the detailed clinical examination , medical and dental history , tooth mobility , and radiographic assessment as described in our previous study .
isolation and storage of dna and genotyping of samples were conducted in the laboratory of the department of pathophysiology , faculty of medicine , masaryk university , brno , czech republic .
genotyping of two snps in il-17 , il-17a 197a / g ( rs2275913 ) , and il-17f + 7488c / t ( his161arg , rs763780 ) was based on polymerase chain reaction using 5 nuclease taqman assays ( c_15879983_10 , c_2234166_10 , resp . ) .
reaction mixture and conditions were designed according to the manufacturer 's instructions ( thermo fisher scientific , waltham , ma , usa ) and fluorescence was measured using the abi prism 7000 sequence detection system .
sds version 1.2.3 software was used to analyze real - time and endpoint fluorescence data .
dna - microarray analyses of oral pathogens based on a periodontal pathogen detection kit ( protean ltd .
, ceske budejovice , czech republic ) were previously used and described . bacterial colonization [ aggregatibacter actinomycetemcomitans ( a.a . ) , tannerella forsythia ( t.f . ) , p.g .
, prevotella intermedia ( p.i . ) , treponema denticola ( t.d . ) , peptostreptococcus micros ( p.i . ) , and fusobacterium nucleatum ( f.n . ) ] in subgingival sulci / pockets was investigated in a subgroup of controls ( n = 51 ) , cp patients ( n = 182 ) , and t1 dm patients with cp ( n = 38 ) before subgingival scaling .
this test determined the individual pathogens semiquantitatively as follows : ( ) undetected , which corresponds to the number of bacteria less than 10 , ( + ) slightly positive corresponding to the number of bacteria 10 to 10 , ( + + ) positive corresponding to the number of bacteria 10 to 10 , and ( + + + ) strongly positive , with the number of bacteria higher than 10 . cultivation of periodontopathic bacteria and immunological examination were performed in the laboratory of the institute of clinical and experimental dental medicine , general university hospital and first faculty of medicine , charles university , prague , czech republic .
il-17 levels were measured in a subgroup of 15 healthy controls and 30 patients with cp .
il-17 levels were determined in mononuclear cells isolated from 20 ml of heparinized blood using the luminex multiplex method ( luminex 100tm analyzer , r&d systems , usa ) . the isolation , cultivation , and stimulation of cells by selected bacteria ( a.a .
, p.g . , and p.i . ) and mitogens or heat shock protein ( hsp ) 70 were described in detail in our previous article .
standard descriptive statistics were applied in the analysis : absolute and relative frequencies for categorical variables and mean with standard deviation ( sd ) or median with quartiles for quantitative variables . to compare independent groups , one - way analysis of variance ( anova ) and kruskal - wallis ( anova )
the differences in the allele frequencies were tested by the fisher - exact test ; hardy - weinberg equilibrium ( hwe ) and genotype frequencies were calculated by the chi - square test ( ) .
the association was described by odds ratios ( or ) with 95% confidence intervals ( 95% ci ) .
the mean ages and bmi between the healthy controls and patient groups did not differ significantly ( p > 0.05 ) .
there were also no significant differences between the subjects with t1 dm or cp and the controls relating to males / females ratio or smoking status .
all diabetic patients ( n = 38 ) who were examined at the periodontology department were affected by periodontitis .
duration of dm and diabetic complications ( dn , dr , and dpn ) in the whole diabetic cohort versus subgroup of t1 dm patients with cp were not statistically different .
both studied polymorphisms were in the hwe in the control group ( p > 0.05 ) .
considering the fact that , in the czech population , snp il-17f + 7488c / t ( his161arg , rs763780 ) tt genotype occurred in 93.7% , we analyzed this polymorphism only in the subgroup of subjects ( n = 190 , data not shown ) .
the allele and genotype frequencies of the il-17a 197a / g ( rs2275913 ) variant are shown in table 2 .
while the genotype frequencies were not different between the controls and cp or t1 dm patients , the a allele was marginally associated with an increased risk to t1 dm ( p < 0.05 , or = 1.36 , 95% ci = 0.961.92 ) . moreover ,
mean levels of hba1c were significantly elevated in carriers of the a allele ( aa and ag genotypes in comparison to gg homozygotes ) in a group of t1 dm patients ( 76.6 mmol / mol versus 69.8 mmol / mol , p < 0.05 , table 3 ) .
although no significant differences in the il-17a allele or genotype frequencies between patients with cp and healthy controls were found in the whole set ( table 2 ) , stratification of subjects according to smoking status revealed the following differences : in healthy subjects , the a allele frequency was higher in smokers ( p < 0.05 , or = 1.62 , 95% ci = 0.972.70 ) , whereas , in cp patients , this allele was found more frequently in nonsmokers ( p < 0.05 , or = 0.64 , 95% ci = 0.411.02 ) .
although a similar distribution of alleles or genotypes between the groups of control nonsmokers versus cp nonsmokers was found , frequencies of the a allele ( p < 0.01 , or = 2.14 , 95% ci = 1.193.83 ) , aa genotype ( p < 0.05 , or = 3.17 , 65% ci = 0.8911.28 ) , and aa + ag versus gg genotypes ( p < 0.05 , or = 1.82 , 95% ci = 0.814.09 ) were more frequent in the control smokers in comparison with the smokers with cp ( table 4 ) .
however , as the associations detected between the given subgroups were only of borderline significance and numbers of the individuals in the subgroups were small , the results obtained should be interpreted carefully .
a subanalysis performed separately in the groups of females ( n = 269 ) and males ( n = 254 ) showed no significant difference in the il-17a 197a / g ( rs2275913 ) allele or genotype frequencies ( data not shown ) . due to the small number of t1 dm patients with confirmed cp , this group was not analyzed according to gender or smoking status .
possible links between the il-17a 197a / g ( rs2275913 ) variant and the occurrence of seven selected periodontal bacteria in subgingival pockets were analyzed .
occurrence in 182 cp patients ( 34.9% versus 19.6% , p < 0.05 , or = 2.20 , 95% ci = 1.034.73 ) and a similar but nonsignificant trend was observed for the presence of p.i .
( 36.0% versus 28.7% , p = 0.09 , or = 1.40 , 95% ci = 0.892.20 ) . on the other hand , in patients with t1 dm and cp carrying a allele of the il-17a 197 polymorphism , t.d . in subgingival biofilm occurred less frequently than in subjects without this allele ( 26.9% versus 50.0% , p < 0.05 , or = 0.37 , 95% ci = 0.131.01 , table 5 ) . in subgroups of nonsmokers ,
the il-17a 197 a allele carriers had an increased risk for the occurrence of p.i . in patients with cp only ( 39.6% versus 28.7% , p < 0.05 , or = 1.63 , 95% ci = 0.962.76 , table 5 ) .
the il-17a 197 snp was not associated with the occurrence of any other bacteria ( including p.g . ) , from those seven selected ones ( data not shown ) .
we analyzed il-17 levels in relation to the il-17a 197a / g ( rs2275913 ) polymorphism in selected patients with cp and healthy controls .
the il-17 levels were measured after a 3-day in vitro cultivation of mononuclear cells , without or with stimulation by dental plaque bacteria , mitogens , or hsp70 in the cp patients ( n = 30 ) .
carriers of genotype with the a allele of il-17a 197a / g ( rs2275913 ) snp had a higher production of il-17 by unstimulated monocytes ( 0.98 pg / ml versus 0.27 pg / ml , p < 0.05 ) and also after stimulation with p.g .
( 1.51 pg / ml versus 0.10 pg / ml , p < 0.05 ) than gg homozygotes ( table 6 ) . in the healthy controls
( n = 15 ) , unstimulated il-17 levels were 0.10 ( 0.080.26 ) pg / ml ( median ; 2575 quartiles ) without any significant relationship with il-17a polymorphism .
after pooling both groups ( n = 45 ) , production of il-17 was significantly associated with il-17a polymorphism in the unstimulated mononuclear cells ( p < 0.05 ) , but not after stimulation by p.g .
il-17a 197a / g snp had no significant effect on il-17 production after stimulation with other periodontal bacteria , hsp70 , and/or mitogens ( data not shown ) .
inflammation is a physiological immune response triggered during infection and injury in an attempt to prevent infection and promote regeneration .
regulation of inflammation is a complex process , tightly controlled by signaling messengers of the immune system , such as cytokines . il-17a and il-17f , produced mainly by th17 cells ,
have been found to be involved in the pathogenesis of autoimmune diseases including diabetes and chronic inflammation , such as periodontitis [ 12 , 15 , 3741 ] .
we evaluated il-17a 197a / g ( rs2275913 ) and il-17f + 7488c / t ( his161arg , rs763780 ) snps in a group of adults with and without t1 dm and/or cp from czech population .
as the present study identified a low variability of il-17f at position + 7488c / t ( similarly as other studies in other populations : http://www.snpedia.com/index.php/rs763780 ) , the tt genotype occurred in 93.7% , and no cc homozygote was detected , we investigated this polymorphism only in a subgroup of 190 subjects .
further , no associations of this polymorphism with aggressive periodontitis ( agp ) or cp [ 3133 ] have been previously found .
in contrast , the il-17a 197a / g snp was analyzed in the whole set of our 523 subjects .
the minor allele frequency ( maf ) of this snp was 0.36 , which is in line with the allele frequency in other european population . to this date
, no study investigating an association of the il-17a 197a / g or il-17f + 7488c / t variants with t1 dm or periodontitis in european white population has been published .
although no significant differences were found in the genotype frequencies between the healthy subjects and t1 dm or cp patients , the a allele was marginally associated with an increased risk of t1 dm ( p < 0.05 ) .
this allele displayed a higher affinity for the nuclear factor of activated t cells ( nfat ) , a critical transcription factor involved in the il-17 regulation [ 43 , 44 ] .
espinoza et al . reported that healthy individuals possessing the a allele of il-17a 197a / g ( rs2275913 ) produced significantly more il-17 after in vitro t cells stimulation than those without this allele .
described that uncontrolled expansion of th17 cells was involved in t1 dm pathology and might exert essential effects on its development . in the studied diabetic population , significantly higher levels of hba1c were present in t1 dm carriers of the genotype with the a allele ( aa + ag genotypes ) versus the gg homozygotes ( 76.6 mmol / mol 16.5 mmol / mol versus 69.8 mmol / mol 13.9 mmol / mol ) .
to our knowledge , no previous study has focused on this issue ; however , polymorphisms in other genes , for example , il-6 and il-18 separately or in combination with the il-12b gene , have been associated with higher concentration of hba1c in t1 dm populations .
in addition , we found no significant differences in the il-17a 197a / g ( rs2275913 ) allele or genotype frequencies between the healthy subjects and patients with cp , not even after stratification by sex ( data not shown ) .
no studies on this topic from european but only from iranian and brazilian populations have been reported . in the iranian population ,
the cc genotype of another il-17a variant ( rs10484879 ) was associated with cp and peri - implantitis .
three brazilian studies examined variability in the il-17a 197a / g ( rs2275913 ) gene in relation to periodontal disease with controversial results . in the study by saraiva et al .
, the a allele was associated with the absence of periodontitis , but corra et al .
and zacarias et al . found the aa genotype and the a allele as a risk factor for cp . even in the separate subgroup of czech patients with cp and t1 dm
, no relationship between il-17a polymorphism and periodontal status ( pd = probing pocket depth , cal = clinical attachment loss , etc . ) was found . however , grsoy et al .
recently described the association between pd and il-17 levels in saliva of type 2 diabetic patients , but independently of glycemic status .
interestingly , the allele and genotype distributions of the il-17a variant in the subgroup of t1 dm patients with cp were closer to the values in nondiabetic cp than t1 dm patients . the different findings in czech population may be due to differences in european versus brazilian populations .
in contrast to findings in the brazilian cohort where the aa genotype was identified as a risk factor for cp in nonsmoker caucasians , our results showed no differences in distribution of the il-17a 197a / g alleles or genotypes between healthy and periodontitis nonsmokers . however ,
the g allele and the gg genotype were marginally significantly associated with an increased risk of periodontitis in smokers .
analysis of the allele frequencies in nonsmokers versus smokers showed borderline significant differences in both studied groups but in the opposite trend , in which 68.1% versus 56.8% for healthy controls and 64.5% versus 73.8% for patients with cp .
due to a relatively small number of subjects in the individual subgroups , number of comparisons performed , and only marginally significant differences , our results should be interpreted carefully . in the next step , according to the hypothesis about biological functions and regulation of il-17 which plays a role in host defense , we assessed the il-17a gene variability in relation to the presence of periodontopathic bacteria in subgingival pockets in patients with cp and t1 dm + cp . in cp population , il-17a 197 a allele carriers had an increased risk of t.f .
occurrence and , in cp nonsmokers only , this allele increased risk of the occurrence of p.i . , but the same a allele was protective for the presence of t.d . in subgingival
the specific il-8 variants were associated with subgingival colonization with a.a . in agp and t.f . in cp in the czech population .
. also found that il-8 haplotype influenced the presence of the red complex bacteria in gingival sulci .
[ 5256 ] focused on a correlation between the pathogenic bacterial colonization and variability in il-6 and fc receptor genes .
additionally , snps in the il-1 gene cluster , interferon , and il-2 were associated with the presence of various periodontopathic bacteria , especially a.a . and the red complex bacteria .
however , in our study , no other bacteria from those studied were associated with il-17a 197 variant and there were no significant differences in the occurrence of these bacteria among groups . finally , in functional study , we associated il-17 production in vitro by blood mononuclear cells with the il-17a 197a / g ( rs2275913 ) gene polymorphism in the subgroup of patients with cp . in czech periodontitis patients ,
il-17a 197 aa + ag carriers had higher il-17 levels in unstimulated mononuclear cells than gg homozygotes .
our results are in accordance with the conclusion of espinoza et al . , who connected the a allele with increased il-17 levels in vitro after t cells stimulation .
even greater differences in il-17 production were measured in cp carriers with the a allele in genotype after stimulation with p.g .
induced innate cell il-17 production and promoted th17 polarization . in a pooled group of cp and healthy subjects ( n = 45 ) ,
production of il-17 was associated with the il-17a polymorphism only in unstimulated mononuclear cells , but not after stimulation by p.g . , other periodontal bacteria , hsp70 , and/or mitogens .
. demonstrated that serum , saliva , and gingival crevicular fluid , il-17a levels were higher in periodontitis patients and correlated positively with clinical parameters ( pd , cal , and bop = bleeding on probing ) . findings of the present study also demonstrated increased il-17 levels in unstimulated monocytes in patients with periodontitis versus healthy controls ( 0.48 pg / ml versus 0.10 pg / ml ; median )
. however , the comparison of absolute values of il-17 levels in healthy subjects with results of other studies would require the use of the same method for the cytokine determination ( including a kit from the same supplier ) , type and preparation of samples , and age of subjects [ 59 , 60 ] .
the present study is mainly limited by relatively low numbers of subjects and especially by the fact that from the group of 125 t1 dm subjects , only 38 patients were evaluated for periodontal status .
the negative findings of single marker analysis in this subgroup could be a result of a lack of statistical power to detect minor differences ( small effect of genes / gene variants in multifactorial diseases is typical ) .
in addition , most of the associations found were tightly below statistical significance ( p < 0.05 ) without multitest corrections .
therefore , risk of relatively high false discovery rate means that our results should be interpreted with caution .
secondly , levels of il-17 in plasma or in gingival tissue were not measured and the presence of periodontal pathogens was examined only in the 271 subjects .
this is the first study of the il-17 gene polymorphisms in t1 dm population and in european patients with cp that was conducted in a relatively homogenous population of white caucasians in central europe of the czech origin .
secondly , the size of studied healthy subjects and cp patients is greater than in previous iranian or brazilian studies .
thirdly , we examined not only the polymorphisms alone but their relationship with clinical , bacterial , and biochemical parameters , which allowed a better biological assessment of the detected associations .
in conclusion , il-17a gene variability may partially influence t1 dm control and the red complex bacteria occurrence in patients with cp and diabetic patients with cp .
additionally , our findings confirmed the functional relevance of the il-17a polymorphism with higher il-17 secretion in the individuals with the a allele .
however , the results of this study need to be proven in a larger independent cohort .
Output:
| interleukin-17 contributes to the pathogenesis of type 1 diabetes mellitus ( t1 dm ) and chronic periodontitis ( cp ) .
we analyzed il-17a 197a / g and il-17f + 7488c / t polymorphisms in t1 dm and cp and determined their associations with il-17 production and occurrence of periopathogens . totally 154 controls , 125 t1 dm , and 244 cp patients were genotyped using 5 nuclease taqman assays .
bacterial colonization was investigated by a dna - microarray kit .
production of il-17 after in vitro stimulation of mononuclear cells by mitogens and bacteria was examined by the luminex system .
although no differences in the allele / genotype frequencies between patients with cp and t1 dm + cp were found , the il-17a 197 a allele increased the risk of t1 dm ( p < 0.05 ) .
levels of hba1c were significantly elevated in carriers of the a allele in t1 dm patients ( p < 0.05 ) .
production of il-17 by mononuclear cells of cp patients ( unstimulated / stimulated by porphyromonas gingivalis ) was associated with il-17a a allele ( p < 0.05 ) .
il-17a polymorphism increased the number of tannerella forsythia and treponema denticola in patients with cp and t1 dm + cp , respectively ( p < 0.05 ) .
il-17a gene variability may influence control of t1 dm and the red complex
bacteria occurrence in patients with cp and t1 dm + cp .
our findings demonstrated the functional relevance of the il-17a polymorphism with higher il-17 secretion in individuals with a allele . |
PubmedSumm118673 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: to evaluate clinical features of infectious keratitis at a tertiary referral center in a rural area of korea .
medical records of 70 patients who were diagnosed with infectious keratitis and underwent corneal culture were reviewed .
age distribution showed one peak at sixth and seventh decade , and 48 patients ( 68.6% ) were 50 years old .
gram - positive bacteria were most common ( ten patients , 66.7% ) , followed by gram - negative bacteria ( three patients , 20% ) and fungi ( two patients , 13.3% ) . in this study , 34.3% of patients were treated by at least one topical antimicrobial before culture .
patients who received topical therapy before culture showed positive culture rate of 16.7% , and patients who underwent corneal culture without topical antibiotics showed positive culture rate of 23.9% .
however , there was no statistically significant difference between the two groups in positive culture rate ( p=0.554 ) .
the proportions of the elderly and male patients were higher than the young and female patients , respectively .
gram - positive bacteria were the most common pathogens , and ocular surface disease was the most common predisposing factor .
infectious keratitis is potentially devastating disease that can lead to serious visual impairment.1,2 to prevent permanent vision loss , early identification of causative organisms and prompt initiation of adequate antibiotics are important.3,4 understanding the recent characteristics of infectious keratitis including predisposing factor and microbiologic profile are essential in the treatment of the condition .
clinical features of the disease vary according to age , area of inhabitation , socioeconomic status and general condition , and may also change over time.57 recently , for instance , infectious keratitis associated with contact lens ( cl ) wear in younger patients has increased with the corresponding widespread use of cl.57 profiles of infectious keratitis have been reported worldwide , including those from korea.1,3,5,6,812 however , to the best of our knowledge , information regarding infectious keratitis of patients residing in rural korea has never been reported . in this study
, we investigated the clinical features of infectious keratitis including predisposing factors and microbiological profile at a tertiary referral center in rural area of korea .
this retrospective study included 70 patients who were diagnosed with infectious keratitis and underwent corneal culture at kangwon national university hospital from june 2007 to october 2014 .
medical records were reviewed and analyzed for data including demographics , microbiologic profile , and predisposing factors .
ethical approval and patient consent was not obtained because this is a retrospective study in which only review of medical records was done . in every case , scraping on the corneal lesion with a sterile blade was performed , and culture of the corneal sample was done using blood agar plate , chocolate agar plate , thioglycollate broth , sabouraud s agar , and brain heart infusion broth .
if there was growth on the cultures , gram staining and potassium hydroxide mount were performed .
most patients received combination of topical 10% cefazolin and 2% gentamicin as a primary antibiotics treatment , and topical levofloxacin or moxifloxacin was used in some cases . in cases with corneal ulcer greater than 3 mm in diameter or rapidly progressing inflammation , 3.1% vancomycin and 2% amikacin were chosen as a primary treatment .
antifungal agents including 0.5%3% amphotericin or 1% voriconazole were also initiated in cases with suspicious fungal infection .
positive culture rates according to previous use of antibiotics were compared using fisher s exact test , and p - value < 0.05 was considered significant .
the mean age of all subjects was 56.717.0 years ( range , 688 years ) .
forty - eight patients ( 69% ) were 50 years old , whereas eight patients ( 11% ) were < 40 years old .
details of age and sex distribution are shown in figure 1 . regarding predisposing factors ,
corneal erosion was the most common disease ( 36 patients ) , followed by recurrent corneal erosion ( 3 patients ) , herpes keratitis ( 3 patients ) , bullous keratopathy ( 2 patients ) , graft - versus - host disease ( 2 patients ) , neurotrophic ulcer ( 1 patient ) , and chemical burn ( 1 patient ) .
two of those patients had history of cataract surgery , and one patient had history of patch graft surgery due to scleromalacia perforans .
one patient had received glaucoma filtration surgery and the remaining one patient had a history of pars plana vitrectomy .
four of them had trauma with organic material and five patients had metallic foreign body in cornea .
predisposing factors of infectious keratitis are summarized in table 1 . in 15 patients ( 21% ) ,
positive culture rate was 17% ( 4 of 24 cases ) in patients with prior treatment with antibiotics , and 24% ( 11 of 46 cases ) in those who did not receive antibiotics treatment .
however , no statistically significant difference was found in culture positive rate between the two groups ( p=0.554 , fisher s exact test ) .
single microorganism was isolated in 14 patients , and two organisms were identified in one patient .
gram - positive bacteria was most common ( ten patients , 67% ) , followed by gram - negative bacteria ( three patients , 20% ) and fungi ( two patients , 13% ) .
in the present study , we evaluated clinical features of infectious keratitis including age and sex distribution , predisposition factors , and microbiologic profile .
the age distribution showed single peak in patients aged in their 50s and 60s , and only 11% of patients aged < 40 .
the results are inconsistent with the recent studies that demonstrated bimodal age distribution in the young and in the elderly.57 cl - related infectious keratitis was only two cases ( 3% ) in this study , which is in discordance with those of the previous studies in korea that 26%40% of infectious keratitis was associated with cl wear.13,14 studies conducted in other countries also demonstrated that 30%50% cases of infectious keratitis were associated with cl wear , and the incidence is higher in patients aged in their 20s and 30s.7,15 these results could be explained by the fact that kangwon province is a rural area where proportion of elderly population is higher and only small population of youngsters reside . in the present study ,
the proportion of male patients was higher than female patients , which is in agreement with the male preponderance in the elderly reported in another study.16 it is conceivably due to the fact that males are more susceptible to trauma . in this study , 14 of 15 patients with infectious keratitis associated with corneal trauma were male .
the results that ocular surface disease was most common predisposing factor for infectious keratitis correspond well with the previous reports.5,7,16,17 corneal trauma was the second common predisposing factor .
infectious keratitis after corneal trauma is common in undeveloped countries or rural areas,7,18,19 and decreased with economic development and urbanization.15,19 the relatively high proportion of corneal trauma might be explained by the fact that most of the patients included in this study were the elderly residing in rural areas and live on farming , thus having an increased risk of corneal trauma and exposure to pathogens .
positive culture rate was 21% , which is lower compared to the results of previous studies that causative microorganism was identified in 40%68% of cases.1,57,9,20,21 empirical antibiotics treatment , slow growth of microorganisms on culture media , other causes of keratitis including virus and improper corneal sampling might account for the low positive culture rate in this study.8 patients with prior topical therapy had lower positive culture rate compared to those who did not receive antibiotics treatment before referral , although the difference was not statistically significant .
prior studies demonstrated that empirical use of antibiotics is associated with decreased positive culture rate.1,6 meanwhile , van der meulen et al6 showed the rate that culture outcomes affected modification of initial antibiotic therapy was only 4.5% , suggesting the effectiveness of empirical treatment with antibiotics . with the development of antibiotics , such as fourth - generation quinolone including moxifloxacin and gatifloxacin , the effectiveness of empirical treatment with commercially available antibiotics can be enhanced .
for instance , sharma et al22 recently revealed that 0.5% moxifloxacin monotherapy is equally effective as combination therapy using fortified cefazolin and tobramycin in the treatment of moderate bacterial corneal ulcers . in this study ,
gram - positive bacteria were the most frequently identified pathogen , and staphylococcus species was the most common gram - positive bacteria , which is in agreement with previous reports.1,7,20,23 by contrast , several recent studies demonstrated high incidence of keratitis caused by gram - negative bacteria , especially pseudomonas aeruginosa.5,6,21,24 prior studies in korea also reported that pseudomonas species was the most common pathogen.13,14 the results of the present study are in discordance with those studies , conceivably because of low proportion of cl - related keratitis . although this study has a limitation that only a small numbers of patients at one tertiary referral center were included , we believe that this study provides updated data of infectious keratitis in a rural area of korea , and can be informative particularly regarding infectious keratitis in rural areas .
Output:
| purposeto evaluate clinical features of infectious keratitis at a tertiary referral center in a rural area of korea.resultsthis was a retrospective study .
medical records of 70 patients who were diagnosed with infectious keratitis and underwent corneal culture were reviewed .
data including demographics , predisposing factors , and microbiological profiles were collected and analyzed.resultsage distribution showed one peak at sixth and seventh decade , and 48 patients ( 68.6% ) were 50 years old .
the male to female ratio was 43 ( 61.4%):27 ( 38.6% ) .
ocular surface disease was the most frequently found ( 48 cases , 68.6% ) .
gram - positive bacteria were most common ( ten patients , 66.7% ) , followed by gram - negative bacteria ( three patients , 20% ) and fungi ( two patients , 13.3% ) . in this study , 34.3% of patients were treated by at least one topical antimicrobial before culture .
patients who received topical therapy before culture showed positive culture rate of 16.7% , and patients who underwent corneal culture without topical antibiotics showed positive culture rate of 23.9%
. however , there was no statistically significant difference between the two groups in positive culture rate ( p=0.554).conclusionthe proportions of the elderly and male patients were higher than the young and female patients , respectively .
gram - positive bacteria were the most common pathogens , and ocular surface disease was the most common predisposing factor . |
PubmedSumm118674 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: a growing body of literature relates the use of machine learning methods to build classification functions from features of interest extracted from medical imaging data ( e.g. , magnetic resonance images ( mri ) , positron emission tomography ) .
we focus specifically on applications within the context of aid to clinical diagnostic in alzheimer 's disease ( ad ) and/or the prediction of future clinical status for individuals with mild cognitive impairment ( mci ) , a putative precursor to ad [ 16 ] .
these techniques have in common the reduction of large , high - dimensional image vectors into smaller features spaces and the identification of a low - dimensional discriminating function .
authors have reported attempts to further simplify the discriminating function by calculating a single , quantitative scalar measure , for example , the structural abnormality index score , the structural - functional biomarker score , and the disease evaluation factor .
while the first two rely on support vector machine analysis of a feature space composed of grey matter concentration patterns , the latter relies on linear kernel approaches to data reduction and classification of mri appearance , defined as the combination of t1-weighted intensity and local volume shape characteristics for all voxels within a volume of interest . using the same features of interest
as described in , we propose a different morphological factor formulation , extensible to other modalities and to other sources of data .
we derive the formulation and estimate its efficiency within the context of aid to diagnostic in probable ad by verifying the hypothesis that it accurately describes current and future clinical status .
a total of 349 subjects were included in this study , with ethics approval obtained from each institution represented .
the first cohort , or reference group , consisted in 149 young , neurologically healthy individuals obtained with permission from the icbm database , whose scans were used to create a reference feature space of image data .
the second cohort , or ad test group , consisted in 150 subjects : 75 patients with a diagnosis of probable ad ( ad group ) and 75 age - matched controls ( ctrl group ) without neurological or neuropsychological deficit .
the probable ad subjects were individuals with mild to moderate probable ad recruited among outpatients seen at the irccs fatebenefratelli ( brescia , italy ) between november 2002 and january 2005 .
ctrl subjects were taken from an ongoing study of the structural features of normal aging at the same center .
all subjects were followed a minimum of 3 years after inclusion ; this longitudinal clinical evaluation constitutes our reference diagnostic .
the third cohort , or mci test group , consisted in 49 mci subjects taken from a prospective project on the natural history of mci , carried out at the irccs fatebenefratelli .
the project was aimed to study the natural history of nondemented persons with apparently primary cognitive deficits , that is , deficits not due to psychic ( anxiety , depression , etc . ) or physical ( hypothyroidism , vit . b12 and folate deficiency , uncontrolled heart disease , uncontrolled diabetes , etc . )
patients were rated with a series of standardized diagnostic and severity instruments , including the mini - mental state examination ( mmse ; ) .
in addition , patients underwent diagnostic mri and laboratory testing to rule out other causes of cognitive impairment .
these inclusion and exclusion criteria for mci were based on previous seminal studies [ 1416 ] .
all mci patients underwent a yearly follow - up visit , consisting of complete clinical and neuropsychological examination , from 1 to 4 years after enrolment . in those individuals that converted to dementia ,
status was ascertained according to clinical diagnostic criteria for ad , subcortical vascular dementia , dementia with lewy bodies , and frontotemporal dementia . within the larger prospective cohort of 100 mci patients enrolled from april 2002 to december 2006 , we have selected patients retrospectively for this study based on
their ( a ) having been followed clinically a minimum of 48 months after their baseline mr scan ; ( b ) having remained either stable ( mci - s group ; n = 29 ) or progressed to probable ad ( mci - p group ; n = 20 ; mean progression 1.5 yrs ; sd 0.7 yrs ) .
data for the last subject ( validation subject ) was obtained with permission from the pilot , multicentric european adni project ( e - adni ) .
it consisted in a healthy volunteer that acted as human quality control phantoms and that was scanned three times at irccs fatebenefratelli ( scan ; repeat scan , same session ; rescan ) on the same day .
the icbm subjects from the reference group were scanned in montreal , canada on a philips gyroscan 1.5 t scanner ( best , netherlands ) using a t1-weighted fast gradient echo sequence ( sagittal acquisition , tr = 18 ms , te = 10 ms , 1 mm 1 mm 1 mm voxels , flip angle 30 ) .
mri data for probable ad , ctrl , mci , and e - adni subjects were acquired at the irccs fatebenefratelli on a single philips gyroscan 1.0 t scanner ( best , netherlands ) using a t1-weighted fast field echo sequence ( sagittal acquisition , tr = 25 ms , te = 6.9 ms , 1 mm 1 mm 1,3 mm voxels ) .
we provide an overview of the automated image processing methodology , which follows essentially the steps outlined in duchesne et al . with some modifications .
images from all subjects were processed in an identical fashion using a publicly available toolkit ( minc : http://www.bic.mni.mcgill.ca/servicessoftware/homepage ) .
processing included intensity inhomogeneity correction , nonlocal means denoising , intensity scaling , global and linear registration , extraction of a predetermined volume of interest centered on the medial temporal lobes , nonlinear registration within the volume of interest towards a common reference target , and computation of log - determinants of the jacobian of the deformation field .
the first data reduction step was to construct a feature space based on the n = 149 subjects from the icbm reference group . to this end , we used principal components analysis ( pca ) of two high - dimensional image vectors within a volume of interest centered on the medial temporal lobe to generate a low - dimensional feature space for classification : ( 1 ) the t1-weighted mri intensity within the volume of interest , transformed into z - score ; and ( 2 ) log - determinants within the volume of interest . with pca we moved from a massive amount of data ( 2 149 4e10 voxels ) to a lower subspace model of maximum n-1 dimensionality , further restricted by using only the first k eigenvectors that contribute up to a given threshold r in the description of the total variance of the system :
( 1)rk=kj=1pj .
once the reference eigenspace was formed , the reference group data was no longer used .
we then proceeded by projecting rasterized vectors of intensity and local volume changes for subjects in the ad and mci test groups into the reference space .
the distribution of eigencoordinates along any principal component for a given population was assessed via quantile plots and shapiro - wilke statistics for normal distribution . following the projection , we used a system of supervised linear classifiers to identify the hyperplane that best separated the groups under study ( e.g. , ctrl versus probable ad ; mci - s versus mci - p ) .
to this end , the data was first normalized to guard against variables with larger variance that might otherwise dominate the classification .
we employed forward stepwise regression analysis via wilk 's method to select the set of discriminating variables { f } , with f n 1 , forming the discriminating hyperplane .
the morphological factor is based on the concept of distance along the restricted set of eigenvectors { f}. in the image - based feature space , this distance d can be calculated in a number of different fashions . we propose initially the signed difference between subject eigencoordinates along the eigenvector f and the mean of the ctrl distribution for that eigenvector , denoted mctrl ; as this distance increases the likelihood of belonging to the ctrl group decreases :
( 2)dif = xifmctrlf .
we propose the euclidean distance between position pi of each subject si and both ctrl and probable ad means along the restricted set of eigenvectors { f } in all f directions , with f n 1 . as the distance to one
center decreases , the distance to the second should increase . in ( 3 ) we demonstrate the distance to the mean of the probable ad group :
( 3)dsicmad=f(pifmadf)2 .
it is possible to weigh each eigenvector by an associated measure of significance , for example , wilk 's from the stepwise regression analysis or a factor derived from univariate t - tests .
while the wilk 's is trivially obtained from the regression analysis , an univariate weight such as the koikkalainen factor formulation entails performing a t - test comparing the group eigencoordinate distributions ( e.g. , ctrl versus probable ad ; mci - s versus mci - p ) for each eigenvector of the restricted set , resulting in the p - value p(f ) for that distribution ; from these p - values the significance weight sf is calculated ,
( 4)sf = ln min [ p(f),0.05]ln 0.05ln 0.000001ln 0.05
.
the significance increases as the differences between the ctrl and ad groups grow and reaches zero when there is no statistically significant difference ( at the p = .05 level ) between both distributions . the resulting weighted distance di combines the aforementioned distances ( manhattan , euclidean ) with a weight sf ( either wilk 's or koikkalainen factor ) over all eigenvectors f from the restricted set { f } as follows :
( 5)di=ifsfdiffsf .
as the final formulation , we extend the principle of image - based distance to the context of an attraction field that follows netwon 's law of universal gravitation , whereby any two elements of mass m within the feature space will exert upon one another an attractive force that will vary proportionally to the inverse of the square of the distance between them . in our context
the force exerted by one group ( e.g. , ctrl ) decreases as the distance between a subject and the center of mass of the ctrl group grows , while the force exerted by the second group ( e.g. , probable ad ) increases as distance decreases between the same subject and the second group 's center of mass . in a multiple group scenario ,
the calculated combined force serves as a quantitative measure of the likelihood of belonging to one of the groups .
in such a classical formulation the force between any subject si with mass mi , to the centers of mass of , for example , the ctrl group ( cmctrl ) and the ad group ( cmad ) , is expressed as :
( 6)fsictrl , ad = gmi(cmctrldsicmctrl2cmaddsicmad2 )
with
( 7)cm=1mimipi ,
being the formulation for the centers of mass calculations , where m is the total mass for all subjects in the group , mi their individual masses , and pi their individual positions in feature space as derived in the previous section .
the distance metric that can be used can be anyone of the aforementioned distances ; for the purposes of the current study , the euclidean distance as formulated in ( 3 ) was employed .
we chose to retain the concept of mass even though it has no real bearing within the present context of an image - based feature space .
it could be replaced with different information regarding individuals in the groups , for example , braak histopathological staging .
alternatively , one can vary the specificity and sensitivity of the attraction field by increasing the mass of subjects in one of the groups ( e.g. , ctrl or probable ad ) . for these purposes
however we set the mass of each subject to unity , and , further , for equal considerations of simplicity , we set the gravitational constant g also to unity . as is , the result is an inverse - squared law relationship . statistics and measurements were computed using the matlab statistics toolbox ( the mathworks , natick , ma ) .
once the reference space was created , all of the experiments that we conducted were performed in a leave - one - out fashion whereby one subject from the study groups was temporarily removed , allowing for an independent estimate of the low - dimensional discriminant function and the calculation of the eigendistribution means and centers of mass .
only then was the left - out subject entered in the system and its morphological factor computed .
the final results consist in the comparison of the independently acquired morphological factors for each subject .
we ran three distinct experiments : ( a ) determination of the relative accuracies of each distance formulation ( manhattan , euclidean , weighted distance ( wilk 's ) , weighted distance ( koikkalainen ) , gravitational model ) for the discrimination of ctrl versus probable ad ; ( b ) determination of the accuracy of the best distance formulation for the discrimination of mci - s versus mci - p ; ( c ) determination of the resolution of the best distance formulation based on the ctrl versus probable ad discriminant function using the e - adni scan - rescan dataset .
there were no statistically significant differences for age between the 75 probable ad and 75 nc individuals ( p > .05 ) in the ad test group .
there was a statistical difference for age between the mci - s and mci - p groups ( p = .001 ) and for baseline mmse ( p = .01 ) ( see table 1 ) .
we set the variance ratio r ( see equation ( 1 ) ) to 0.997 , resulting in a reference pca model composed of 256 intensity and local volume change eigenvectors .
we proceeded with forward stepwise regression analysis using wilk 's method ( p - to - enter = .005 ) to select the discriminating variables forming the hyperplane separating each group ( e.g. , ctrl versus probable ad ; mci - s versus mci - p ) .
this was performed in a leave - one - out fashion to eliminate overlearning of the dataset . the median number of eigenvectors f retained in the discriminating function for either ctrl versus probable ad or mci - s versus mci - p was four .
table 2 displays the different accuracies obtained for the five different formulations for the morphological factor at the task of discriminating ctrl versus probable ad ( leave - one - out ) .
the gravitational model 's accuracy was 90% , superior to the weighted distance models . using the gravitational model , we report the results for the morphological factor for the ctrl versus probable ad experiment and the mci - s versus mci - p experiment in table 3
. the distributions of morphological factors for all groups , alongside quantile plots to assess normality ( ctrl and probable ad groups ) are shown in figures 1 and 2 .
the receiver operating characteristic ( roc ) curve for the task of discriminating ctrl from probable ad shows the trade - offs possible in sensitivity and specificity ( figure 1(c ) ) .
the area under the roc curve was 0.9444 . at the 90% accuracy point ( 135/150 ) , specificity was 87.5% and sensitivity 92.9% . with the gravitational model we computed the roc curve for the discrimination of mci - s from mci - p ( figure 2(c ) ) .
the area under the roc curve was 0.7940 . at 72.3% accuracy , specificity was 62% and sensitivity 75% .
finally , we computed the morphological factor for the e - adni human phantom volunteer , using the ctrl and probable ad cohorts as a training group for the determination of the discriminating function . using the gravitational model , the average factor value was 0.4 or 4 standard deviations away from the mean of the ctrl distribution , with an average difference in scan - rescan factor of 4% .
notably , the morphological index obtained via a weighted distance method ( koikkalainen factor ) had an average difference in scan - rescan factor of less than 1% .
the gravitational or inverse - squared law model constitutes a novel development in the strategies towards obtaining a single quantitative factor from data reduction and machine learning of very high - dimensional mri input data towards discrimination of individual subjects .
its inherent flexibility makes multigroup comparisons trivial , alongside the introduction of other sources of data .
its performance compares favorably to other results in the mri literature within the context of discriminating ctrl versus probable ad . as a single dimensional scalar ,
the morphological factor metric achieves strong accuracy ( 90% ) , especially when compared to other multidimensional discrimination functions ( e.g. , 92% as reported in ) .
it has also a strong result when put within the clinical context of discriminating ctrl versus probable ad , where inclusion evaluations are reportedly 78% accurate ( albeit against final histopathological diagnostic ) .
while lower , accuracy figures for the prediction of progression to probable ad in the mci cohort ( on average , 1.5 years before clinical diagnostic ) are also strong and compare favorably to published results on mri data [ 4 , 6 ] .
a study comparing these approaches ( e.g. , within a monocentric setting , such as the open access series of imaging studies or multicentric setting such as the alzheimer 's disease neuroimaging initiative ) would be worthwhile .
the paper uses the leave - one - out approach to feature selection ( stepwise regression analysis ) , which allows a correct generalization of the morphological factor as it is not tested on the same data . clinical interpretation of changes in image features associated with changes in the morphological factor should provide insight into the development of ad and would need to be compared to existing results from voxel - based morphometry studies , structural studies ( e.g. , hippocampal and entorhinal atrophy ) , and histopathological confirmation studies .
overall , we speculate that the specific patterns of intensity and local volume change differences result from different levels of advanced extracellular plaque formation , neurofibrillary tangles accumulation and other pathological processes between ctrl and probable ad , and between stable and progressing mci . with regards to the features employed in this method
, the differences in local volume changes should mirror the changes noticed in other reports , such as visual assessment , while differences in grey level might reflect the intensity of neuronal loss induced by the neuropathological changes , which precede volume loss as visualized on mri .
the difference in factor averages between probable ad and ctrl was 15% . at this level ,
the minimum trial size required to detect this difference is 59 individuals for both samples ( = 0.05 ; = 0.50 ) and reaches 75 individuals if we include scan - rescan variability .
one pertains to the fact that the mri images for the probable ad subjects were acquired at the time of diagnosis ; therefore , some of the patients have had ad for a number of years . in turn
, this implies that extensive neurodegeneration has taken place at this point and should artificially facilitate the discrimination with ctrl .
however , the fact that the latter were age matched and the fact that the results in the mci cohort remain significant alleviate part of this concern
. it would be useful to assess if the morphological factor correlates with different indices of disease severity , cognitive deficits , or other biomarkers .
finally , the patterns of abnormalities that can be found by the method are restricted to a space that is built from healthy , young controls .
it is not the optimal space to describe normal aging and/or ad - related variability .
however , it does tend to maximize the distance between both groups , as we noticed from building a few reference spaces in an n - fold validation of the ctrl / probable ad groups that achieved lower accuracies .
we estimate that the proposed formulation of the morphological factor is relevant within the context of aid to diagnostic and prediction of future clinical status in probable ad .
Output:
| we propose a novel morphological factor estimate from structural mri for disease state evaluation .
we tested this methodology in the context of alzheimer 's disease ( ad ) with 349 subjects .
the method consisted in ( a ) creating a reference mri feature eigenspace using intensity and local volume change data from 149 healthy , young subjects ; ( b ) projecting mri data from 75 probable ad , 76 controls ( ctrl ) , and 49 mild cognitive impairment ( mci ) in that space ; ( c ) extracting high - dimensional discriminant functions ; ( d ) calculating a single morphological factor based on various models .
we used this methodology in leave - one - out experiments to ( 1 ) confirm the superiority of an inverse - squared model over other approaches ; ( 2 ) obtain accuracy estimates for the discrimination of probable ad from ctrl ( 90% ) and the prediction of conversion of mci subjects to probable ad ( 79.4% ) . |
PubmedSumm118675 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input:
Output:
| artificial particulate systems such as lipid vesicles are found in a variety of biomedical applications such as drug delivery and targeting .
more versatile layers of control would be added if liposomes could be glued together on demand while stabilized against fusion . here , we present a two - component molecular glue composed of a protein and calcium ions , with each component specialized for fast and specific binding to negatively charged lipid membranes . upon mixing the two components , the high affinity binding of this glue starts to tightly bridge two lipid vesicles on a subsecond scale .
furthermore , highly charged liposomes are beneficial in preventing spontaneous fusion before applying the molecular glue . |
PubmedSumm118676 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: long non - coding rnas can activate cellular pathways that lead to tumorigenesis , in analogy to protein - coding oncogenes .
the molecular mechanisms by which lncrnas exert their biological functions has been extensively reviewed by ( wang and chang , 2011 ) .
one example of such an oncogenic lncrna is metastasis - associated in lung adenocarcinoma transcript 1 ( malat1 ) , a nuclear - retained non - coding rna that has been recently shown to regulate alternative splicing by modulating serine / arginine ( sr ) splicing factor phosphorylation ( tripathi et al . , 2010 ) .
increased expression of the lncrna malat1 has been first observed in metastatic non - small cell lung cancer ( ji et al .
, 2003 ; see details in the next section ) , followed by endometrial stromal sarcoma of the uterus ( yamada et al . , 2006 ) , and more recently in six other types of cancer , including hepatocellular carcinoma , breast , pancreas , lung , colon , and prostate cancers ( lin et al . , 2007 ) .
recently , short hairpin rna inhibition of malat1 in human cervical cancer cells was shown to suppress cell proliferation and invasion ( guo et al . , 2010 ) , whereas rna interference - mediated silencing of malat1 reduced the in vitro migration of lung adenocarcinoma cells by influencing the expression of motility - related genes ( tano et al . , 2010 ) . altogether , these findings reinforce the role of malat1 as an oncogenic lncrna , and point to one of the possible modes of action of lncrnas , namely through their interaction with and modulation of splicing factor proteins .
the mode of action of lncrnas through the interaction with chromatin remodeling complexes may be a more general one , as it has been documented for two lncrnas .
one example is anril ( antisense non - coding rna in the ink4 locus ) that is altered in an estimated 3040% of human tumors ( kim and sharpless , 2006 ) .
tumor suppressor p15 is silenced by its antisense anril transcript ( yu et al . , 2008 ) ; lncrna anril is required for the recruitment of polycomb prc1 and prc2 complexes to the ink4b locus and for silencing of p15 tumor suppressor gene ( yap et al . , 2010 ;
another example is hotair ( hox antisense intergenic rna ) , a metastasis - associated gene located in the mammalian hoxc locus that reprograms chromatin state to promote cancer metastasis ( gupta et al . , 2010 ) .
hotair lncrna interacts with polycomb repressor complex prc2 , determining prc2 localization and repression of the hoxd locus ( rinn et al . , 2007 ) .
recently it was found that hotair serves as a scaffold for at least two distinct histone modification complexes .
hotair binds the prc2 complex responsible for h3k27 methylation and also lsd1 , a histone lysine demethylase that mediates enzymatic demethylation of h3k4me2 ( tsai et al . , 2010 ) .
although the precise mechanism of hotair activities remains to be elucidated , it is clear that hotair participates in silencing of metastasis suppressor genes thus promoting metastasis , as discussed below .
cancer gene profiling studies have had an enormous impact on understanding of the biology of cancers , pointing to the biological heterogeneity of specific cancer types , providing identification of novel oncogenes and tumor suppressors , and defining pathways that interact to drive the growth of individual cancers ( cowin et al . , 2010 ) .
large - scale genomic studies are underway , such as the cancer genome atlas project that aims to catalog in each cancer type the changes in dna copy number and methylation , as well as in small ( 1925 nt ) non - coding microrna ( mirna ) and protein - coding mrna expression ( cancer_genome_atlas_research_network , 2008 , 2011 ) .
noteworthy , changes in expression of lncrnas have not been analyzed in these large cohort studies .
identification of lncrnas correlated to cancer has benefited in the past decade from the development of a number of effective high - throughput expression analyses technologies as well as from the increasing realization that lncrnas may play important roles in physiological and pathological processes in the cell ( see table 1 ) .
early efforts to identify molecular cancer markers based on the screening of cdna libraries enriched in tumor - specific transcripts have identified lncrnas whose expression levels correlate to cancer . using a differential display approach , the lncrna dd3 , later named prostate cancer antigen 3 ( pca3 ) ,
was initially identified as overexpressed in prostate tumors relative to benign prostate hyperplasia and normal epithelium ( bussemakers et al . , 1999 ) .
further studies later indicated that pca3 is a very specific prostate cancer gene whose mechanism of action is still not identified ( marks and bostwick , 2008 ; shappell , 2008 ) .
another report that used large - scale transcriptome analysis to look for differential gene expression in cancer and gave attention to a differentially expressed lncrna , namely malat1 , employed a subtractive hybridization approach to determine differences in gene expression between primary non - small cell lung cancer tumors of five patients that were cured by surgery and tumors of four patients that subsequently metastasized ( ji et al . , 2003 ) .
in all , 26 transcripts were found more than once , and among them the novel lncrna named malat1 .
subsequently , 31 samples from stage i patients suffering from adenocarcinoma or squamous cell carcinoma were analyzed by qpcr , and the expression levels of malat1 were significantly higher in metastasizing adenocarcinomas compared to non - metastasizing ones ( p = 0.03 ) ; interestingly , no significant differences in gene expression were found for squamous cell carcinomas ( n = 34 ; ji et al . , 2003 ) .
these data provided evidence that the association of lncrna malat1 with metastasis depended on the lung tumor s histology .
a large - scale gene expression approach specifically designed to look for lncrnas correlated to cancer has employed hybridization of rna derived from normal human breast epithelia , primary breast carcinomas , and distant metastases to ultra - dense tiling arrays covering the entire hox gene loci ( gupta et al . , 2010 ) .
the authors found that 233 transcribed regions in the hox loci , comprising 170 lncrnas and 63 hox exons , were differentially expressed ( gupta et al . , 2010 ) , with a systematic variation in the expression of hox lncrnas among normal breast epithelia , primary tumor , and metastases .
dozens of hox lncrnas were expressed in normal breast but showed reduced expression in all cancer samples ; conversely , a set of hox lncrnas was frequently expressed in primary tumors but not in metastases ( gupta et al . , 2010 ) .
notably , one such metastasis - associated lncrna was hotair , which had a unique association with patient prognosis ( gupta et al . , 2010 ) .
oligoarrays were used to interrogate 481 ultra conserved regions ( ucrs ) in the human genome ( calin et al . , 2007 ) ; ucrs are a subset of conserved sequences that are located in both intra- and intergenic regions and are absolutely conserved ( 100% ) between orthologous regions of the human , rat , and mouse genomes ( bejerano et al . , 2004 ) .
a total of 256 ucrs ( 53% ) were identified as non - coding genomic regions ( bejerano et al . , 2004 ) .
the authors investigated the expression of ucrs in a panel of 173 samples , including 133 human cancers [ e.g. , chronic lymphocytic leukemias ( cll ) , colorectal ( crc ) , and hepatocellular carcinomas ( hcc ) ] and 40 corresponding normal tissues ( calin et al . , 2007 ) .
specific sets of ucrs were differentially expressed in distinct tumor types , and among them , 42 were non - coding ucrs ( 48% of the differentially expressed ucrs ) .
this work demonstrated that the transcribed ucr expression profiles can be used to differentiate human cancers ( calin et al . , 2007 ) .
custom - designed cdna microarrays interrogating selected sets of protein - coding genes and lncrnas from intronic / intergenic genomic regions were used for obtaining expression profiles from clinical samples of a number of cancer types ( reis et al . , 2004 ; brito et al . , 2008 ; tahira et al . ,
rna from 27 patient tumor samples with gleason scores ranging from 5 to 10 were hybridized to these custom - designed microarrays ( reis et al . , 2004 ) .
among the 56 transcripts that were found to be significantly correlated to the degree of prostate tumor differentiation ( gleason score ) , 23 were lncrnas mapping to intronic regions ( reis et al . , 2004 ) . among the top twelve transcripts most significantly correlated to tumor differentiation , six were antisense intronic lncrnas as shown by orientation - specific rt - pcr or northern blot analysis with strand - specific riboprobe ( reis et al .
. aberrant expression of intronic lncrnas was studied in clear cell renal cell carcinoma ( rcc ) using matched samples of tumor and adjacent non - neoplastic tissue obtained from six patients ( brito et al . , 2008 ) .
a set of 55 transcripts was significantly down - regulated in clear cell rcc relative to the matched non - tumor tissue ; among the down - regulated transcripts , 49 mapped to untranslated or coding exons of protein - coding genes and 6 were lncrnas mapped to intronic regions in genomic loci of protein - coding genes ( brito et al . , 2008 ) .
more recently , pancreatic ductal adenocarcinoma ( pdac ) was studied , aiming at identifying gene expression profiles of protein - coding and lncrnas correlated to pancreatic cancer and metastasis in 38 clinical samples of tumor and non - tumor pancreatic tissues ( tahira et al . , 2011 ) .
statistically significant expression signatures comprising protein - coding mrnas and intronic / intergenic lncrnas that correlate to pdac or to pancreatic cancer metastasis were identified ; interestingly , loci harboring intronic lncrnas differentially expressed in pdac metastases were enriched in genes associated to the mapk pathway ( tahira et al . , 2011 ) .
whole - genome tiling arrays were utilized to identify the expression of novel lncrnas across the entire human genome ( perez et al . , 2008 ) .
the authors hybridized rna from normal lung cell cultures to the tiling arrays and found 495 transcriptionally active regions originated from non - protein - coding sequence ( intergenic or intronic regions ) and chose 15 candidate rnas for subsequent real - time rt pcr , northern blot , and sequencing experiments of which three were intronic lncrnas ( perez et al . ,
altered expression of these lncrnas was found in patient samples in both breast and ovarian cancers ( perez et al . , 2008 ) .
the first high - throughput sequencing of polya+ rna ( rna - seq ) from a large cohort of 102 prostate tissues and cells lines has been recently reported ( prensner et al . , 2011 ) .
the work has identified 121 unannotated prostate cancer - associated lncrna transcripts ( pcats ) and has characterized one lncrna , pcat-1 , as a prostate - specific regulator of cell proliferation , showing that it is a target of prc2 ( prensner et al . , 2011 ) .
patterns of pcat-1 and prc2 expression stratified patient tissues into molecular subtypes distinguished by expression signatures of pcat-1-repressed target genes .
these findings establish the utility of rna - seq to identify disease - associated lncrnas that may improve the stratification of cancer subtypes ( prensner et al . , 2011 ) .
although the functional consequences of the deregulation of lncrnas in cancer development are currently unknown , the studies discussed above indicate that this class of transcripts may play important functions in both normal and malignant tissues .
molecular markers of malignancy are important diagnostic and prognostic tools that help patient management in the oncology clinics .
cancer is a multi - factorial disease and for most types of malignancies an increase in the number of available assessment and management tools is desirable .
meier analyses as a prognostic parameter for patient survival in stage i non - small cell lung cancer ( ji et al . , 2003 ) .
malat1 has been subsequently validated as a marker for endometrial stromal sarcoma of the uterus ( yamada et al . , 2006 ) and
for hcc and a spectrum of five other human carcinomas ( lin et al . , 2007 ) .
in addition , increased expression of malat1 has been recently shown to be an independent prognostic factor for hcc following liver transplantation ( lai et al . , 2011 ) .
increased expression of lncrna hotair was shown to be associated with metastasis in breast cancer patients , having a unique association with patient prognosis ( gupta et al . , 2010 ) .
subsequently , hotair expression levels was found to correlate with metastasis in colorectal carcinoma ( kogo et al . , 2011 ) , and to predict tumor recurrence in hepatocellular carcinoma ( yang et al . , 2011b ) .
measurement of lncrna pca3 in patient urine samples has been shown to allow more sensitive and specific diagnosis of prostate cancer than the widely used psa ( prostate - specific antigen ) serum levels ( fradet et al . , 2004 ;
the potential of pca3 urine assay to aid prostate cancer diagnosis and minimize unnecessary biopsies has been extensively documented , highlighting its advantages over psa and pointing to future challenges for this new diagnostic biomarker ( lee et al . , 2011 ) .
the lncrna hulc ( highly upregulated in liver cancer ) is highly expressed in hcc patients and can be detected in the blood by conventional pcr methods ( panzitt et al . , 2007 ) .
it has been later shown that hulc lncrna expression is not confined to hcc , but is also expressed in colorectal carcinomas that metastasize to the liver ( matouk et al . , 2009 ) .
diagnosis and treatment follow up of complex multi - factorial diseases such as cancer could conceivably be improved by screening of a larger number of molecular biomarkers in easily accessible sample specimens . in fact , highly stable cell - free circulating nucleic acids ( cfcna ) , both rna and dna species , have been discovered in the blood , plasma , and urine of humans ( tong and lo , 2006 ) . at present , there is evidence of a good correlation between tumor - associated changes in genomic , epigenetic , or transcriptional patterns and alterations in cfcna levels ( schwarzenbach et al . ,
2011 ) , strongly pointing to the utility of this blood biomarker class as promising clinical tools .
the release of nucleic acids into the blood is thought to be related to the apoptosis and necrosis of cancer cells in the tumor microenvironment and is also the result of secretion .
circulating rnas are detectable in the serum and plasma of cancer patients , being surprisingly stable in spite of the fact that high amounts of rnases circulate in the blood of cancer patients .
this implies that rna may be protected from degradation by its packaging into microparticles , which include exosomes , microvesicles , apoptotic bodies , and apoptotic microparticles ( orozco and lewis , 2010 ) .
microparticles are small , membranous vesicles that can contain dna , rna , mirna , intracellular proteins , and extracellular surface markers from the parental cells ; they can be secreted from intracellular multivesicular bodies or released from the surface of blebbing membranes ( cocucci et al . , 2009 ;
the detection and identification of rna in serum and plasma can be carried out using microarray technologies or reverse transcription quantitative real - time pcr ( odriscoll et al . , 2008 ) .
the reported rna content of microvesicles and exosomes thus far includes primarily small mirnas and long protein - coding mrnas ( record et al . , 2011 ) .
recent advances in small non - coding mirna expression profiling in human cancer and their potential as therapeutic targets and novel biomarkers have been reviewed ( farazi et al . , 2011 ; munker and calin , 2011 ) .
the presence of small non - coding mirnas in serum of cancer patients was first described for diffuse large b - cell lymphoma patients ( lawrie et al . , 2008 ) .
circulating mirnas were subsequently used in assessing patients with prostate cancer ( mitchell et al . , 2008 ) and at present circulating mirnas
have been characterized as potential biomarkers in over ten different cancers ( kosaka et al . , 2010 ) . despite being promising biomarkers for cancer diagnosis and prognosis ,
there have been conflicting findings about circulating mirnas from the same tumor reported from different studies ( kosaka et al . ,
these discrepancies might be due to the lack of an established endogenous mirna control to normalize for circulating mirna levels , and also to the different extraction and quantification methods used among the studies ( kosaka et al . , 2010 ) .
an effort to standardize results is warranted by putting forward recommendations for controlling pre - analytical variables , including the reduction of contaminant cellular mirnas of hematopoietic origin in the isolation and quantization of cell - free circulating rnas ( duttagupta et al . , 2011 ) .
we speculate that in addition to mirnas and mrnas the human serum might contain a considerable amount of lncrnas that will eventually be detected by the use of unbiased high - throughput technologies such as genome tiling expression microarrays or rna - seq deep - sequencing of serum samples .
such approaches should be subjected to the same controls regarding pre - analytical variables ( duttagupta et al . , 2011 ) , including the reduction of contaminant hematopoietic cells in the isolation and quantization of cell - free circulating lncrnas .
comparative studies of lncrnas in serum from cancer patient large cohorts and from normal subjects will possibly reveal novel circulating lncrnas as potential biomarkers in many types of cancers .
long non - coding rna expression profiles in human cancers have highlighted the potential value of this class of non - coding rnas as tumor markers in patient diagnosis and prognosis .
the rapidly expanding catalog of lncrnas holds promises that in the near future lncrnas will become ever more important in cancer patient management .
an analogy can be made with the impact of small mirna profiling in many types of cancer ( braconi et al .
, 2011 ; ferracin et al . , 2011 ; schetter and harris , 2011 ; wang and sen , 2011 ) , which has provided different experimental lines of evidence that deregulation of mirnas not only results as consequence of cancer progression but also directly affects gene networks that promote tumor initiation and progression in a cause - effect manner ( lovat et al . , 2011 ) .
as the catalog of lncrnas grows , it will become important to elucidate the genetic networks and pathways regulated by the abnormally expressing lncrnas in cancer cells as a means to understanding the role of these lncrnas in the induction of malignant transformation .
the authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest .
Output:
| long non - coding rnas ( lncrnas ) transcribed from intergenic and intronic regions of the human genome constitute a broad class of cellular transcripts that are under intensive investigation .
while only a handful of lncrnas have been characterized , their involvement in fundamental cellular processes that control gene expression highlights a central role in cell homeostasis .
not surprisingly , aberrant expression of regulatory lncrnas has been increasingly documented in different types of cancer , where they can mediate both oncogenic or tumor suppressor effects .
interaction with chromatin remodeling complexes that promote silencing of specific genes or modulation of splicing factor proteins seem to be two general modes of lncrna regulation , but it is conceivable that additional mechanisms of action are yet to be unveiled .
lncrnas show greater tissue specificity compared to protein - coding mrnas making them attractive in the search of novel diagnostics / prognostics cancer biomarkers in body fluid samples .
in fact , lncrna prostate cancer antigen 3 can be detected in urine samples and has been shown to improve diagnosis of prostate cancer .
we suggest that an unbiased screening of the presence of rnas in easily accessible body fluids such as serum and urine might reveal novel circulating lncrnas as potential biomarkers in many types of cancer .
annotation and functional characterization of the lncrna complement of the cancer transcriptome will conceivably provide new venues for early diagnosis and treatment of the disease . |
PubmedSumm118677 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: the emergence of mci as a health problem and the expansion of cognitive morbidity at a population level are clearly related to the general phenomenon of population aging . as gruenberg pointed out in 1977 , it is one of the failures of success that , while medical research has reduced the mortality of disease , it has concurrently extended life expectancy and increased the proportion of persons in the community with chronic pathologies .
analyses of longitudinal health survey data from the usa by kramer in the early 1980s provided early empirical evidence of the rapid expansion of dependency due to cognitive disorders arising from increases in disease incidence , better management of its physiological consequences , and thus decreased direct mortality this public health dilemma was , in fact , predicted by jonathan swift in the early 18th century in gulliver 's travels , he described the cognitive consequences of extended longevity in eternal beings , who , on reaching the age of 80 and in the absence of degenerative disease , continue to perform daily activities but have difficulty in recalling the names of common objects and recently read material , forget the name of friends , and consequently have diminished pleasure in life .
it is a description that comes quite close to current definitions of mci , and distinguishes mci from normal aging and dementia . referring to the latter , whom he describes as those who turn to dotage
, he suggests that they may be more fortunate in that they elicit pity rather than ridicule . the extent to which mci may be a disabling process is largely unknown because the usual definition proposed by petersen and colleagues , and adopted by most researchers in this area , stipulated that mci is a state that does not interfere with everyday activities .
more recently , this definition has been relaxed to include the possibility that mci may impede , but not prevent , everyday functioning . on this basis
, it has subsequently been shown that mci may be associated with increasing difficulties in the performance of a wide range of everyday tasks , notably dressing , dental care , and the use of a telephone .
we do not know , on the other hand , to what extent mci may indirectly lead to activity restriction due to , for example , withdrawal from a social activity due to fear of being embarrassed by a memory problem .
little is currently known either about the extent to which mci may influence mortality rates . while dementia has been clearly associated with increased mortality with a life expectancy on average of 8 years from the time of diagnosis , the impact of mci on survival remains unclear .
cumulative mortality risk in mci has been estimated by gussekloo et al using a cox proportional hazards model with a cohort of 891 subjects from the leiden aging study compared with normal subjects the cumulative risk was found to be 2.5 .
the study is however , limited by its use of the mini - mental - state examination ( mmse ) to define mci .
establishing the prevalence and incidence of mci has above all been hindered by the lack of an operational definition of the disorder adapted to general population use , where case selection can not normally be based on a complete neurological examination .
early conceptualizations of subclinical cognitive deficit were based on the theoretical assumption that such changes are distinct from dementia and other pathologies , being the consequence of inevitable aging - related cerebral changes , such as cortical atrophy , which may be considered a normal feature of the aging process . as parallel research into the causes of dementia and cerebrovascular disease
has now led to a clearer understanding of their etiology , it has also been shown that many of the physiological abnormalities seen in these disorders are also present to a lesser extent in normal subjects with cognitive complaints , but these factors can not currently be incorporated into diagnostic criteria due to difficulties in establishing precise universal cutoff points between mci and normal subjects .
the diagnostic criteria for mci proposed by petersen et al thus refer to complaints of defective memory and demonstration of abnormal memory functioning for age , which may be more easily quantified by reference to standard deviation from scores obtained by normal elderly subjects .
the remaining criteria are principally exclusion criteria : normal general cognitive functioning and conserved ability to perform activities of daily living .
mci is considered above all to be a prodrome of alzheimer 's disease and , variably , of other dementias .
mci criteria refer to poor cognitive functioning as assessed at one point in time , thus precluding an appreciation of decline over time ; it is thus difficult to differentiate from cohort effects , low iq , and education .
later definitions by petersen et al refined the initial concept by referring to memory impairment beyond that expected for both age and education level this has been the working definition adopted by most epidemiological studies . the definition of mci has been developed within a clinical setting .
as such , the definition represents a minimal set of distinguishing criteria , the diagnosis resting largely on the overall clinical picture .
validation of the criteria has been in terms of their capacity to predict conversion to dementia and/or alzheimer 's disease .
the two are often used interchangeably , which has led to some confusion in the comparison of results across centers .
conversion rates to dementia are also noted for some studies . the conversion rate from mci to dementia in clinical samples
together , these studies suggest the predictive validity of the concept within a clinical setting .
these studies are all , however , based on clinical series conducted in specialist centers , so it is not certain to what extent they represent all cases of mci found in the general population . clinical signs and symptoms beyond those cited in the official mci criteria
have also been used for diagnosis , so there is likely to be some differences in case identification between centers .
while these studies together suggest the high predictive validity of the concept within a clinical setting , they are unable to provide us with information on prevalence and incidence . to date ,
only a small number of general population studies have been conducted using mci criteria , giving a range of prevalence estimations from 3% to 19% .
there are significant differences in sampling frames , cognitive tests , and drop - out due to mortality and refusal between these studies ; nonetheless , the majority of authors report rates of around 3% when mci criteria are strictly applied ( table ii ) .
subjects in three of the studies reporting higher rates have received extensive clinical examinations as well as cognitive testing , which may have led to the inclusion of subjects on the basis of clinical criteria beyond those stipulated in the definition of mci . in three studies ,
the authors conclude in their discussion that the criteria are too strict and a large number of subjects are subsequently excluded who would be considered by clinicians as a high - risk group . the principal problems with existing criteria
are reported to be in the areas of subjective reporting of memory problems and intact activities of daily living . modifying the criteria to allow for absence of subjective memory problems and permitting
changes in ability to perform activities of daily living was found by all three studies to increase mci prevalence to give rates between 3% and 19% .
both clinicians and epidemiologists have found the restriction of mci to an isolated memory deficit difficult to apply in practice .
firstly , isolated memory dysfunction is relatively rare ; estimated at about 6% of all cases of subclinical cognitive deficit , at a clinical level it is very difficult to define as even specific memory tests involve other cognitive functions , such as language comprehension and attention .
a recent working group of clinicians and epidemiologists working in the area of mci met in stockholm in 2003 and proposed new working criteria for mci , which take into account the difficulties described above and provide clearer guidelines for clinical research . the new stepwise algorithm , which also defines subtypes of mci ,
is based around the following three diagnostic features : not normal , not demented ( does not meet diagnostic and statistical manual of mental disorders fourth edition [ dsm - ivj or international classification of mental and behavioral disorders
[ icd-10 ] criteria for a dementia syndrome ) . cognitive decline indicated by subject and/or informant report and objective cognitive tests .
it is hoped that the application of these new diagnostic guidelines will increase the comparability of clinical studies and thus produce more accurate estimates of disease prevalence .
overall population studies have shown somewhat lower conversion rates from mci to dementia than clinical studies , which is not surprising given the more heterogeneous nature of the cognitive deficit likely to be seen in this setting .
three studies permit us to make estimates of incidence of 8 , 26 , and 58 new cases per thousand subjects annually yesavage et al have attempted to model incidence rates using a first - order markovian chain model to predict transition from normality to mci based on published prevalence , incidence , and conversion data .
they found a new case rate from normality to mci starting at 10 per 1000 at age 60 and increasing to reach 110 per 1000 at age 85 .
the proposed model probability estimates are based on recent data on incidence , prevalence , and conversion rates ; however , these we have seen to be divergent .
the model also relies on age - specific ad prevalence rates derived from a us study , which are lower than those observed in european meta - analyses .
numerous clinical and population studies have examined risk factors for mci conversion to dementia , but far fewer the risk of transition to mci from normal cognitive functioning .
clinical case - control studies have provided cross - sectional information on differences between mci and normal aging with relation to brain structure and function , and cognition . compared with normal subjects , mci groups are seen above all to manifest left medial temporal lobe atrophy and smaller medial temporal lobe volumes .
other studies have suggested that white matter lesions , particularly in periventricular areas , are associated with mci .
these findings suggest that the clinical risks for conversion from normal to mci are principally related to degree of impairment along a continuum from normal aging - related changes to dementia .
clinical cohort studies have provided very little information on other health factors , or psychological , behavioral , and environmental risks for transition to mci .
two general population epidemiological studies have attempted to isolate clusters of risk factors by regression analysis based on a wide range of clinical and sociodemographic factors .
tervo et al examined a range of demographic , vascular , and genetic factors , and found the most significant risk factors to be age ( odds ratio [ or ] 1.08 ) , apolipoprotein e4 ( apoe-4 ) allele ( or 2.04 ) , and medicated hypertension ( or 1.86 ) .
high educational level was found to be a protective factor ( or 0.79 ) and the combination given the highest risk was medicated hypertension plus apoe-4 ( or 3.92 ) .
risk factors for mci were also examined from the multisite longitudinal cardiovascular health study . in this large study of 3608 subjects , which included neuropsychological and neurological tests ,
general medical examination , and magnetic resonance imaging ( mri ) , the principal risk factors for mci were found to be african - american race , low educational level , digit symbol test score , cortical atrophy , mri - identified infarcts , and depression .
this study also examined mci subtypes and found risk factors for amnestic mci to be infarcts , apoe-4 allele , and low mmse scores , while for multiple domain mci risk factors were mmse and digit symbol test scores .
it is difficult , however , to consider cognitive scores as a risk factor for mci , as they are part of the diagnostic algorithm used to select cases .
data from a third study , the kungsholmen project in sweden , also suggested that certain psychiatric symptoms may be predictive of mci , notably anxiety ; however , this study did not use the usual mci criteria to identify cases . examining the various risk factors that have been isolated for conversion from normal functioning to mci , it is possible to construct a hypothetical model of risk .
figure 2 shows theoretical pathways ( in black ) to mci incorporating most of the known risk factors , which can be seen to be largely those for dementia .
there are , however , insufficient population data at present to permit either a statistical calculation of transition probabilities in relation to individual risk factors or a maximum likelihood calculation to assess the overall predictive value of possible competing hypothetical general models .
finally , the role of interventional epidemiology is to suggest possible intervention points within a hypothetical etiological model to guide research into therapeutic intervention .
it appears increasingly likely that mci , like dementia , is the result of multiple lifetime insults in combination with genetic vulnerability factors .
the different points at which intervention may be likely to reduce risk have been added on to the theoretical model in blue in figure 2 .
a more complete clinical discussion of treatment possibilities in mci has been developed in the paper in this issue by gauthier . at the present time
, there is clearly no specific treatment for mci , but it may be possible to reduce overall risk by a number of simple strategies , which do not in themselves have adverse consequences .
these include the management of cardiovascular and cerebrovascular risk factors such as high blood pressure from early adult life onward to reduce the risk of infarcts and white matter lesion accumulation , controlling for depression , and the provision of adequate learning opportunities from childhood .
other more active and contentious intervention therapies for mci , such as use of statins , anti - inflammatory agents , the anticholinesterase therapies currently used in the treatment of dementia , and hormonal replacement therapy , are being evaluated , but there is currently insufficient evidence for their widespread population use in the prevention of mci .
it has been demonstrated within a longitudinal population study that , by entering mci risk factors into a regression equation , a probability statistic of developing dementia over a given time period may be produced ; this may assist clinicians in the decision to undertake a therapeutic intervention that has adverse side effects .
an avenue for future research in conjunction with the provision of cholinergic system therapies is to explore to what extent the overall cholinergic burden may be reduced by the readjustment of other medication being taken by an elderly person .
a very wide range of drugs have anticholinergic effects , often unknown to the general practitioner , and it is not known to what extent these may be a common risk factor for mci .
the administration of anti - cholinergic agents , such as scopolamine , in healthy young subjects has been shown to produce very similar cognitive deficits to mci .
the range of drugs with known anticholinergic effects is very large and includes such commonly prescribed drugs as the antihistamines , bronchodilators , antidepressants , antiulcer medication , preanesthetics , and even some herbal teas .
it has been estimated that around a third of nursing home patients in the usa take more than two anticholinergic drugs and 5% more than five .
it is surprising that this important environmental risk factor has not been taken into account in epidemiological studies of environmental risk in mci .
mci rates are likely to increase rapidly in parallel with the extension of life expectancy at higher ages .
current estimates of prevalence are limited by problems related to case identification , but , in the light of several revisions of the original definition , appear to be converging at around 5% of the general population with around 15% per year going on to develop dementia .
while the principal value of mci remains the identification of persons in the first stages of neurodegenerative disease , it also covers other forms of cognitive impairment due to multiple causes , making the construction of meaningful hypothetical etiological models extremely difficult .
the few studies of risk that have been carried out have largely focused on known risk factors for dementia and there is a clear need for longitudinal epidemiological studies that examine a wider range of genetic , biological , demographic , and environmental risk factors .
such studies are extremely costly and difficult to justify for a health state that is subclinical , poorly defined , often benign , and for which no specific treatment is currently available .
epidemiologists in this area should explore the possibility of grafting this type of study on to existing longitudinal databases of population aging , which cover a much broader range of risk factors than those included in studies of dementia .
Output:
| mild cognitive impairment ( mci ) refers to cognitive impairment that is assumed to be due to pathological central nervous system processes , but which interacts with normal aging - related changes .
epidemiological studies conducted in the general population have been able to examine more heterogeneous forms of this disorder than clinical studies , and have also been able to provide early estimations of population incidence and prevalence .
large differences in case identification procedures and sampling methods have led to considerable divergence in the rates of prevalence reported , which ranged from 1% to 29% . suggested improvements in the definition of mci have led to an upward adjustment of prevalence rates in most studies , giving between 5% and 29% .
incidence is estimated as 8 to 58 new cases per thousand persons per year , and the probability of conversion from mci to dementia is estimated at around 15% .
the principal risk factors that have been identified so far for mci using regression models applied to general population data are age , education , race , medicated hypertension , infarcts , white matter lesions , depression , and apolipoprotein e4 ( ap0e-4j allele .
an etiological model derived from these studies indicates possible intervention points for future therapeutic strategies at the level of both clinical intervention and environmental exposure .
there is , however , a clear need for epidemiological studies that take into account a broader range of risk factors than those studied to date , which have focused principally on known risk factors for dementia . |
PubmedSumm118678 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: a single - center , prospective , non - randomized comparative case series study was conducted after gaining institutional review board approval at the hanyang university medical center ( korea ) between september 2009 and december 2010 .
ninety - eight eyes of 63 patients were included , but 14 eyes of 10 patients were lost to follow - up , and 84 eyes of 53 patients were ultimately enrolled in this study .
the inclusion criteria were as follows : patients with diabetes mellitus type 1 or type 2 , who were older than 20 years and newly diagnosed with severe non - proliferative diabetic retinopathy ( npdr ) .
the exclusion criteria were as follows : high myopia ( < -6 diopters ) , high astigmatism ( > 5 diopters ) , presence of disc neovascularization , a history of glaucoma , presence of macular edema ( cmt > 300 m ) , a history of diabetic macular edema , severe medial opacity such as significant cataract or corneal opacity that obscured the field of observation of the fundus , any prior history of surgical treatment or laser photocoagulation , or a history of any other significant ocular disorder of the optic nerve such as optic neuritis , optic neuropathy , uveitis or retinal degeneration . if vitreous hemorrhage , neovascularization of the disc or any other ocular disorders developed in one eye , the involved site was excluded from our study .
because it may be controversial to present absolute indications for prp to treat severe npdr without macular edema , detailed information about prp for severe npdr such as protective effects , complications , rescue photocoagulation for worsening disease , and other factors were provided to patients who were choosing between prp and careful observation .
the pascal group was comprised of 35 eyes with newly - diagnosed severe npdr who agreed to have prp , and the control group was comprised of 49 eyes with severe npdr who agreed to be examined .
all patients underwent examinations of best - corrected snellen visual acuity , intraocular pressure ( iop ) and slitlamp examination of the anterior and posterior segments using a volk superfield lens ( volk , mentor , oh , usa ) .
peripapillary rnfl thickness , cup - disc area ratio of the optic disc and cmt measurements were repeated before pascal photocoagulation ( pascal group ) or at baseline ( control groups ) , and again after two and six months .
pascal ( optimedica , santa clara , ca , usa ) is a frequency - doubled nd : yag laser with a wavelength of 532 nm .
a total of 2,346.4 946.8 ( range , 760 to 4,703 ) laser spots were applied on the superior or inferior halves of the peripheral retina over the course of two sessions .
a laser spot size of 200 m and a pulse duration of 30 ms were used in the pascal groups .
the laser power was increased from 200 mw and adjusted to obtain gray - white burns according to etdrs guidelines .
sixteen spots in a 4 4 square grid pattern were simultaneously applied in a rapid raster sequence with a single foot pedal .
the peripapillary rnfl thickness , cmt and cup - disc area ratio of optic discs were obtained using optical coherence tomography ( stratus oct ; carl zeiss meditec , dublin , ca , usa ) .
the programs for fast rnfl thickness , fast macular thickness and fast optic disc scanning were used .
the peripapillary rnfl thickness was measured in each quadrant ( temporal , superior , nasal , and inferior ) .
the cmt was defined as the average thickness in the central 1,000 m diameter ring of the etdrs layout .
these measurements were repeated two and six months after the initial visit for pascal photocoagulation , and were compared to baseline and between the pascal and control groups .
the relationship between changes in rnfl thickness and the number of laser burns or any other factors were analyzed .
snellen visual acuity measurements were converted to a logarithm of the minimum angle of resolution ( logmar ) score in order to simplify statistical analysis .
pasw ver . 18.0 ( spss inc . , chicago , il , usa ) was used to analyze the data .
demographic data or baseline parameters of the pascal and control groups were compared by the independent samples t - test and chi - square test .
the paired t - test was used to compare differences in peripapillary rnfl thickness , cmt , cup - disc area ratio , and visual acuity before and after pascal photocoagulation in the pascal group or over time in the control group .
simple correlations between the number of laser burns and changes in best - corrected visual acuity ( bcva ) , average rnfl thickness , or cmt were assessed by pearson 's correlation coefficients .
repeated - measure anova was used to compare the difference in interval changes of measurements between the pascal and control groups at the two- and six - month time points , respectively .
the statistical significance level was set at p = 0.05 and 95% confidence intervals were determined .
a single - center , prospective , non - randomized comparative case series study was conducted after gaining institutional review board approval at the hanyang university medical center ( korea ) between september 2009 and december 2010 .
ninety - eight eyes of 63 patients were included , but 14 eyes of 10 patients were lost to follow - up , and 84 eyes of 53 patients were ultimately enrolled in this study .
the inclusion criteria were as follows : patients with diabetes mellitus type 1 or type 2 , who were older than 20 years and newly diagnosed with severe non - proliferative diabetic retinopathy ( npdr ) .
the exclusion criteria were as follows : high myopia ( < -6 diopters ) , high astigmatism ( > 5 diopters ) , presence of disc neovascularization , a history of glaucoma , presence of macular edema ( cmt > 300 m ) , a history of diabetic macular edema , severe medial opacity such as significant cataract or corneal opacity that obscured the field of observation of the fundus , any prior history of surgical treatment or laser photocoagulation , or a history of any other significant ocular disorder of the optic nerve such as optic neuritis , optic neuropathy , uveitis or retinal degeneration . if vitreous hemorrhage , neovascularization of the disc or any other ocular disorders developed in one eye , the involved site was excluded from our study .
because it may be controversial to present absolute indications for prp to treat severe npdr without macular edema , detailed information about prp for severe npdr such as protective effects , complications , rescue photocoagulation for worsening disease , and other factors were provided to patients who were choosing between prp and careful observation .
the pascal group was comprised of 35 eyes with newly - diagnosed severe npdr who agreed to have prp , and the control group was comprised of 49 eyes with severe npdr who agreed to be examined .
all patients underwent examinations of best - corrected snellen visual acuity , intraocular pressure ( iop ) and slitlamp examination of the anterior and posterior segments using a volk superfield lens ( volk , mentor , oh , usa ) .
peripapillary rnfl thickness , cup - disc area ratio of the optic disc and cmt measurements were repeated before pascal photocoagulation ( pascal group ) or at baseline ( control groups ) , and again after two and six months .
pascal ( optimedica , santa clara , ca , usa ) is a frequency - doubled nd : yag laser with a wavelength of 532 nm .
a total of 2,346.4 946.8 ( range , 760 to 4,703 ) laser spots were applied on the superior or inferior halves of the peripheral retina over the course of two sessions .
a laser spot size of 200 m and a pulse duration of 30 ms were used in the pascal groups .
the laser power was increased from 200 mw and adjusted to obtain gray - white burns according to etdrs guidelines .
sixteen spots in a 4 4 square grid pattern were simultaneously applied in a rapid raster sequence with a single foot pedal .
the peripapillary rnfl thickness , cmt and cup - disc area ratio of optic discs were obtained using optical coherence tomography ( stratus oct ; carl zeiss meditec , dublin , ca , usa ) .
the programs for fast rnfl thickness , fast macular thickness and fast optic disc scanning were used .
the peripapillary rnfl thickness was measured in each quadrant ( temporal , superior , nasal , and inferior ) .
the cmt was defined as the average thickness in the central 1,000 m diameter ring of the etdrs layout .
these measurements were repeated two and six months after the initial visit for pascal photocoagulation , and were compared to baseline and between the pascal and control groups .
the relationship between changes in rnfl thickness and the number of laser burns or any other factors were analyzed .
snellen visual acuity measurements were converted to a logarithm of the minimum angle of resolution ( logmar ) score in order to simplify statistical analysis .
pasw ver . 18.0 ( spss inc . , chicago , il , usa ) was used to analyze the data . demographic data or baseline parameters of the pascal and control groups
the paired t - test was used to compare differences in peripapillary rnfl thickness , cmt , cup - disc area ratio , and visual acuity before and after pascal photocoagulation in the pascal group or over time in the control group .
simple correlations between the number of laser burns and changes in best - corrected visual acuity ( bcva ) , average rnfl thickness , or cmt were assessed by pearson 's correlation coefficients .
repeated - measure anova was used to compare the difference in interval changes of measurements between the pascal and control groups at the two- and six - month time points , respectively .
the statistical significance level was set at p = 0.05 and 95% confidence intervals were determined .
the study included a total of 84 eyes of 53 individuals with a mean age of 57 4.5 years ( range , 34 to 80 years ) .
patient demographic and clinical data including age , sex , glycosylated hemoglobin level , bcva , iop and spherical equivalent did not differ significantly between groups ( table 1 ) . at initial workup ,
no statistically significant difference in peripapillary rnfl thickness was detected in any quadrant or in the average between the pascal and control groups .
the cup to disc area ratio and cmt were also not significantly different between the groups ( table 2 ) .
after pascal photocoagulation , the inferior rnfl thickness had increased by 7.88 m ( 133.28 28.81 m ) at two months compared to baseline ( 125.40 32.4 m ) and partially recovered to 3.84 m ( 129.44 31.62 m ) at six months . on the other hand ,
superior , temporal , and nasal rnfl area showed a consecutive decrease in thickness at 2 and 6 months after treatment .
the average rnfl thickness had increased by 0.84 m ( 99.11 18.91 m ) two months after and decreased by 0.4 m ( 97.87 18.79 m ) six months after pascal compared to baseline ( 98.27 18.97 m ) . however , none of these changes were statistically significant
. also , the control group showed no significant change in rnfl thickness ( fig .
cmt increased significantly by 18.11 m ( 236.22 54.89 m , p = 0.048 ) at two months compared to baseline thickness ( 218.11 46.20 m ) and partially recovered to 11.82 m ( 224.40 9.40 m , p = 0.11 ) at six months , whereas cmt did not change significantly over time in the control group ( fig .
no detectable changes in the cup - disc area ratio of the optic disc were observed in either group ( fig .
the mean best - corrected visual acuities at baseline were 0.06 logmar 0.025 in the control group and 0.08 logmar 0.036 in the pascal group .
after pascal photocoagulation , visual acuity decreased slightly to 0.11 logmar 0.031 at two months ( p = 0.14 ) , and partially recovered to 0.10 logmar 0.031 at six months ( p = 0.26 ) .
similarly , visual acuity in the control group decreased slightly to 0.08 logmar 0.014 at the two months ( p = 0.24 ) , and remained at 0.08 logmar 0.039 at six months ( p = 0.23 ) in the control group .
4 ) . there were no significant correlations between the mean number of laser burns and changes in bcva ( pearson 's correlation coefficient r = 0.004 , p = 0.983 after 2 months ; r = -0.020 , p = 0.911 after 6 months ) , average rnfl thickness ( r = 0.166 , p = 0.340 after 2 months ; r = -0.002 , p = 0.989 after 6 months ) or cmt ( r = -0.241 , p = 0.164 after 2 months ;
r = -0.102 , p = 0.558 after 6 months ) after pascal ( fig .
in addition , the presence of hypertension or diabetic nephropathy was not correlated with changes in average rnfl thickness or cmt over time ( table 3 ) .
kim and cho reported a reduction in the nerve fiber layer six months after conventional prp . in an animal study ,
the rnfl thickness increased beyond 30 days after treatment of a 100 m area using an argon laser with 200 mw of power .
described thickening of the rnfl at ten weeks and gradual thinning six months after conventional laser treatment with a multiple - session 100 ms laser using 2,000 burns .
they found that thermal diffusion with longer laser pulse duration caused inner retinal axonal damage and then led to a disruption of the mid - flow axonal flow .
in addition , as time passes , axonal edema and direct damage induced by laser treatment may cause axonal cell death and progressive nerve fiber thinning . in pascal
photocoagulation , a reduced pulse duration should be used to achieve a rapid consecutive raster with a pattern array , so the pulse duration was set to 20 to 30 ms using a semi - automated patterned laser .
our study investigates the effects of the pascal laser with short pulse durations on peripapillary rnfl , cmt and optic nerve morphology .
shorter laser exposure was limited to rpe and photoreceptors and thus caused less damage to the nerve fiber layer by decreasing the axial spread of heat toward the inner retinal layer and providing better spatial confinement of the lesion in an animal study .
defect areas after laser photocoagulation were known to be the junction of the inner and outer segments of photoreceptors and apical rpe regardless of pulse duration .
however , shorter laser duration minimized the amount of burn scars and damage to the nerve fiber layer in an animal study . in our study , there were no significant differences in terms of changes in peripapillary rnfl thickness between the pascal and control groups , unlike the changes observed for conventional prp in previous reports .
the cmt and average rnfl thickness increased two months after pascal photocoagulation and decreased by six months , but these changes were not statistically significant . the early increase in cmt after pascal photocoagulation
could be explained by cytokine secretion when laser photocoagulation induces the hyperpermeability of retinal capillaries .
the slight increase in average rnfl thickness ( 0.84 m ) two months after pascal photocoagulation could also be explained by other factors , such as retinal thickening in the macula .
a slight decrease in peripapillary rnfl thickness was observed six months after pascal photocoagulation , but it was not statistically significant .
the short exposure time of pascal photocoagulation does not result in a significant loss of rnfl over the short and long term .
no changes in optic disc morphology were noted 6 months after pascal . there was a significant increase in mean cmt two months after pascal photocoagulation ( 18.11 m increase , p = 0.048 ) .
we assumed this increase was due to mild intraretinal inf lammation following the thermal spread of the laser itself , even though it has a shorter pulse duration than conventional laser modalities . at six months ,
the cmt had recovered ( 6.29 m increase compared with baseline , p = 0.11 ) . to summarize
, we observed a slight increase in the average rnfl at short term follow - up and recovery at long term follow - up .
we hypothesized that the early decrease in visual acuity was related to the transient initial increase in cmt because of direct injury induced by laser treatment and the hyperpermeability of the retinal vasculature .
however , the change in visual acuity was temporary and not statistically significant at two months and was followed by recovery of visual acuity six months after pascal .
presence of hypertension or diabetic nephropathy and the total number of laser burns were not correlated with changes in cmt or average rnfl thickness over time .
first , the sample size was too small to fully represent a difference in peripapillary rnfl thickness , cmt and optic nerve morphology changes in diabetic retinopathy .
second , our maximum follow - up period was six months . according to previous papers , a significant increase in rnfl at 10 weeks and a reduction in rnfl at 6 months were observed after conventional prp .
therefore , we decided to have 2 months , 6 months , and a year follow - up plans to observe anatomical changes after pascal at the beginning of this study , but many patients had already been lost to follow - up after six months .
third , we measured peripapillary rnfl thickness , cup - disc area ratio and cmt with a stratus optical coherence tomography ( oct ) , which relies on time domain technology .
therefore , it is hard to compare with data from spectral domain oct , which was recently introduced worldwide with improved data acquisition speed .
we believe a larger , multi - center , randomized study with long - term follow - up using spectral domain oct is warranted . in conclusion , pascal photocoagulation , which is a new laser mode for diabetic retinopathy , did not cause significant change in the peripapillary rnfl thickness , cmt , and optic nerve morphology in our study . as in previous studies about prp , conventional prp
is considered a destructive treatment due to longer pulse duration , which can cause a change in rnfl thickness and optic nerve morphology .
we suppose that the main difference between pascal and conventional prp is shorter pulse duration in pascal .
further study should be performed to compare the changes in rnfl thickness and optic nerve morphology between pascal and conventional prp .
Output:
| purposeto evaluate the effect of pattern scan laser ( pascal ) photocoagulation on peripapillary retinal nerve fiber layer ( rnfl ) thickness , central macular thickness ( cmt ) , and optic nerve morphology in patients with diabetic retinopathy.methodssubjects included 35 eyes for the pascal group and 49 eyes for a control group .
peripapillary rnfl thickness , cup - disc area ratio and cmt were measured before pascal photocoagulation and at 2 and 6 months after pascal photocoagulation in the pascal or control groups.resultsthe average rnfl thickness had increased by 0.84 m two months after and decreased by 0.4 m six months after pascal photocoagulation compared to baseline , but these changes were not significant ( p = 0.83 , 0.39 ) .
the cup - disc area ratio was unchanged after pascal photocoagulation .
cmt increased by 18.11 m ( p = 0.048 ) at two months compared to baseline thickness , and partially recovered to 11.82 m ( p = 0.11 ) at six months in the pascal group.conclusionspascal photocoagulation may not cause significant change in the peripapillary rnfl thickness , cmt , and optic nerve morphology in patients with diabetic retinopathy . |
PubmedSumm118679 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: valvular heart disease ( vhd ) is a major health problem afflicting the elderly in particular , with a prevalence of 2.5% in the united states .
calcific aortic valve disease ( cavd ) is initiated as aortic valve sclerosis ( avsc ) , which is a mild thickening of the valve , to aortic valve stenosis ( avs ) , which results in severe impairment of the valve motion .
cavd is increasingly present in the aging population , reaching epidemic proportions , with approximately one third of individuals aged > 65 years , showing sub - clinical evidence of cavd , in the form of aortic sclerosis ( 2 ) . as a large proportion of the worldwide population is becoming aged ,
age , gender , tobacco use , hypercholesterolemia , rheumatic heart disease and hypertension constitute significant risk factors of acquired cavd .
congenital cavd primarily results from the disturbed expression of genes that are involved in normal heart valve development .
congenital valve abnormalities comprise almost 50% of the cases of congenital heart defects ( chd ) ( 4 ) .
advances in the identification of these defects and in the associated care for infants suffering from chds is on the rise , thus increasing the net incidence and burden of congenital valve diseases ( 4 ) .
type ii diabetes is considered an important risk factor for native cavd ( 5 ) .
the pathogenesis of congenital and acquired cavd is likely due to the interplay of genetic and environmental influences , even though the precise mechanisms are not known .
although the incidence of vhd is high , therapeutic approaches for this disease are limited . the only available primary clinical approach for valve repair or replacement is surgery as the primary treatment ( 6,7 ) .
in fact , aortic valve replacement is the second most frequent cardiac surgery following coronary artery bypass grafting ( 8) .
cavd advances to calcific aortic stenosis ( cas ) , which is the most severe form of the disease .
it is extremely debilitating affecting as many as 2% of individuals > 60 years of age , requiring surgery to preclude death , once the symptoms become evident ( 9 ) .
there are also many potential biomarkers that provide clinically useful information regarding the extent , severity , progression and prognosis of cavd ( 8) .
the atrioventricular valves ( mitral and tricuspid ) and the semilunar valves ( aortic and pulmonic ) are two types of mature heart valves .
these valves consist of an outer layer of valve endothelial cells ( vecs ) surrounding three layers of extracellular matrix each with specialized function and interspersed with valve interstitial cells ( vics ) ( 10 ) .
changes in the functionality and localization of matrix components potentially lead to vhd , since the proper organization of extracellular matrix ( ecm ) is essential in maintaining overall valve morphology and normal valve function .
the three layers of ecm , consisting of collagens , proteoglycans and elastin , collectively contribute to the biomechanical support for the valves and any derangements in these morphological units can have detrimental effects on the complicated structures of valves that open and close approximately 100,000 times daily in order to maintain proper directionality of blood flow through the heart chambers ( 11 ) .
the protective endothelium over the surface of the valve leaflets is formed by the vecs , which communicate with vics in the underlying layer and regulate their response to alterations in the blood flow ( 10 ) .
genetic or acquired / environmental causes that disrupt the normal organization and composition of the ecm and communication between vecs and vics alter valve mechanics and interfere with the valve leaflet function , culminating in heart failure ( 11 ) .
the histopathologic heterogeneity of cavd indicates the involvement of diverse cell - dependent mechanisms that regulate calcium load on the valve leaflets ( 12 ) , as well as the participation of different cell types , including interstitial cells , endothelial cells and cardiac chondrocytes , in valve biomineralization ( 13 ) ( fig .
histopathologic studies ( 12 ) demonstrated the presence of calcified nodules composed of amorphous calcium phosphate , without any organization into specific histological structures . in these affected valves ,
similar to atherosclerosis , there are signs of inflammation and bone morphogenetic protein-2 expression ( 12 ) .
additionally , woven and lamellar bone with osteoblast matrix production and vascularization has been identified in calcifying native aortic valves ( 14 ) . during the pathogenesis of cavd , one of the earliest events following endothelial cell dysfunction is the accumulation of lipids and subendothelial matrix at the ventricular surface of the valve with downward displacement of the subjacent elastic lamina while plaque - like subendothelial deposits occur on the aortic surface of the valve .
it has been suggested that vecs via the endothelial - mesenchymal transition ( emt ) , can contribute to calcifying vascular cell types , in response to stimuli that promote arteriosclerotic calcification ( 15 ) .
athough the contribution of acquired immunity to the progression of cavd remains to be determined , recent data indicate that an adaptive immune response is likely activated in cavd as clonally expanded effector - memory t - cell populations are observed in the valve and in the circulation of patients with severe cas ( 16 ) ( fig .
the earliest amorphous calcium phosphate deposition occurs in a stippled pattern on the fibrosal interface with the fibro - fatty expansion of the valve spongiosa ( 17 ) and these calcium deposits form readily via epitaxial mineral deposition on a number of nidi , including cholesterol crystals ( 18 ) , collagen and fragmented elastin fibers ( 19 ) .
coexpression of collagen and alkaline phosphatase , which in the elastin - rich environment can trigger mineralization , has been demonstrated in cavd by immunogold electron microscopy ( 20 ) .
biomineralization also occurs in the absence of alkaline phosphatase , as matrix vesicles contain molecules such as annexin a5 , annexin a6 , and phosphatidylserine , which readily bind calcium and nucleate mineral deposition ( 21 ) while the absence of inhibitors of mineralization such as pyrophosphate , phosphoosteopontin , and fetuin can further promote the deposition of calcium ( 22 ) .
however , following the initiation of mineral deposition , circulating osteoprogenitors ( cops ) derived from myeloid cell lineage arrive to the site and play an important role in the subsequent stages of disease response .
the presence of type i collagen ( + ) cd45 ( + ) cop cells in valves has been detected at the fibroproliferative and neovascularization phases of disease , whereas cd45 ( + ) cells are observed in ossifying and non - ossifying valve segments ( 23 ) .
circulating myeloid calcifying cells , which are positive for alkaline phosphatase and osteocalcin are elevated in type ii diabetes patients , and may contribute to the increased incidence of cavd in these patients ( 24 ) .
inflammation is known to play a significant role in many types of macrovascular calcification , including cavd ( 25 ) .
a number of the inflammation - associated factors , including tumor necrosis factor , interleukin 1- , advanced glycosylation - end products , and oxidized low - density lipoprotein ( oxldl ) cholesterol , activate vascular biomineralization and vascular osteogenic signaling processes ( 26 ) ( fig .
1 ) . aggravated fibrocalcific responses have been observed in cavd in association with increased levels of oxldl ( 27 ) . by employing histological studies on human samples and mouse models , it has been demonstrated that reactive oxygen species , specifically hydrogen peroxide , has a pro - osteogenic and pathogenic role in cavd and that a number of the enzymatic mechanisms that counteract oxidative stress are downregulated in valves during the pathogenesis of cavd ( 28 ) .
specifically , hydrogen peroxide has been shown to activate osteogenic cbfa1/runt - related transcription factor 2 ( runx2 ) and msx2/wnt signaling pathways to promote mineralization and these pathways are activated in calcifying human aortic valves ( 28 ) .
advances in genomic technologies have led to the identification of several genes that contribute to the normal development and function of the four heart valves and to the identification of many genetic abnormalities in some of these genes in congenital form of cavd ( 29 ) .
the most common congenital valve anomalies are bicuspid aortic valve ( bav ) and mitral valve prolapse ( mvp ) .
normal aortic valve develops until there are three cusps , whereas in bav disease there is a fusion of two of the leaflets during development , leading to significant morbidity primarily through valve calcification .
notch1 , a member of the notch signaling pathway , was one of the first mutated genes identified in bav . the jagged / notch signaling pathway , which plays an important role in bone formation is also central to valve morphogenesis and cavd .
jagged1 signals from endothelial cells support the notch1-mediated emt necessary for cardiac valve morphogenesis during the development of heart ( 31 ) .
heterozygous loss - of - function notch1 mutations segregate with the disease in families with autosomal dominant bav ( 32 ) .
2 ) in vics ( 33 ) . mvp affects 23% of the population and is manifested by systolic displacement of a thickened mitral valve leaflet into the left atrium .
this condition is normally observed in adults and often associated with the fibromyxomatous degeneration of the leaflets , valve regurgitation , congestive heart failure , arrhythmias , and infective endocarditis ( 34 ) .
involvement of transforming growth factor- ( tgf- ) , which is needed for remodeling and maintenance of mitral valve , in mvp pathogenesis has been suggested ( 35 ) .
tgf- , bone morphogenetic proteins , and wnt , which act via signaling through alk- and ldl receptor - related protein - receptor complexes to promote bone formation , mineralization , and skeletal homeostasis ( fig .
2 ) , also play an important role in the earliest stages of aortic valve morphogenesis ( 36 ) . a recent genome - wide association study that included
cavd and mitral annular calcification patients identified a single - nucleotide polymorphism ( snp ) in the lipoprotein ( a ) locus only in cavd patients ( 37 ) .
as mentioned previously , surgical valve replacement is the widely accepted treatment of choice for avs , with either mechanical or biological prostheses .
although there are other treatment options , including balloon aortic valvuloplasty or percutaneous valve replacement , they have many limitations .
for example , aortic valvuloplasty showed non - trivial complication rates , but moderately high rates of aortic insufficiency with much higher rates of recurrence ( 38 ) .
percutaneous aortic valve replacement is currently being examined in several studies and appears to be suitable for select groups of patients ( 39 ) .
numerous biomarkers have been suggested for following the pathogenesis of aortic valve disease , but not all biomarkers are clinically useful candidates . presently , asymmetric dimethylarginine , fetuin - a , calcium phosphate product , natriuretic peptides and osteopontin are the most promising candidates . a circulating level of asymmetric dimethylarginine , which is involved in endothelial cell dysfunction , was found to correlate with the extent of avs ( 40 ) .
fetuin - a , an inhibitor of soft tissue calcification , also seems to be a good candidate as its serum levels show strong inverse correlation with the extent of valve degeneration and calcification ( 41 ) .
osteopontin is directly associated with the ectopic calcification process , which occurs during the latter stages of cavd making this protein a specific biomarker for cavd ( 42 ) . in conclusion ,
cavd and other types of vhds are reaching epidemic status in their prevalence in many developed and developing countries .
cavd ranges from avsc , i.e. , mild thickening of the valve , to avs , which is severe impairment of the valve motion .
risk factors for acquired valve diseases include age , gender , tobacco use , hypercholesterolemia , hypertension , and type ii diabetes mellitus .
diverse cell - dependent mechanisms and signaling pathways orchestrate valve biomineralization with the participation of different cell types including interstitial cells , endothelial cells , cardiac chondrocytes , and cops .
in addition , several genetic mutations that cause congenital valve diseases have been identified along with specific snps associated with cavd . despite the many advances ,
there is still a lack of pharmacological treatments for the valve diseases and the most widely accepted approach is surgery .
recent advances in the identification of molecular mechanisms involved in the development and pathogenesis of valvular disease are making a significant impact in our understanding of the heart valve disease .
Output:
| valvular heart disease ( vhd ) is caused by either damage or defect in one of the four heart valves , aortic , mitral , tricuspid or pulmonary .
defects in these valves can be congenital or acquired .
age , gender , tobacco use , hypercholesterolemia , hypertension , and type ii diabetes contribute to the risk of disease .
vhd is an escalating health issue with a prevalence of 2.5% in the united states alone .
considering the likely increase of the aging population worldwide , the incidence of acquired vhd is expected to increase .
technological advances are instrumental in identifying congenital heart defects in infants , thereby adding to the growing vhd population .
almost one - third of elderly individuals have echocardiographic or radiological evidence of calcific aortic valve ( cav ) sclerosis , an early and subclinical form of cav disease ( cavd ) . of individuals ages
> 60 , ~2% suffer from disease progression to its most severe form , calcific aortic stenosis .
surgical intervention is therefore required in these patients as no effective pharmacotherapies exist .
valvular calcium load and valve biomineralization are orchestrated by the concerted action of diverse cell - dependent mechanisms .
signaling pathways important in skeletal morphogenesis are also involved in the regulation of cardiac valve morphogenesis , cavd and the pathobiology of cardiovascular calcification .
cavd usually occurs without any obvious symptoms in early stages over a long period of time and symptoms are identified at advanced stages of the disease , leading to a high rate of mortality .
aortic valve replacement is the only primary treatment of choice .
biomarkers such as asymmetric dimethylarginine , fetuin - a , calcium phosphate product , natriuretic peptides and osteopontin have been useful in improving outcomes among various disease states .
this review , highlights the current understanding of the biology of vhd , with particular reference to molecular and cellular aspects of its regulation .
current clinical questions and the development of new strategies to treat various forms of vhd medically were addressed . |
PubmedSumm118680 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: developmental dyslexia or reading difficulty ( rd ) is a deficit in acquiring fluent reading skills despite remedial intervention ( ida , 2011 ) that is accompanied also by diminished executive functions ( ef ) ( breznitz , 2006 ) .
these difficulties lead to a failure in reading words in a holistic manner ( i.e. , orthographic reading ) ( turkeltaub et al . , 2003 ) .
reading is a higher - order cognitive ability that relies on phonology , orthography , and semantics , along with several key ef [ e.g. , working memory ( de jong , 1998 ) , speed measures ( breznitz and misra , 2003 ) , and switching / shifting attention and cognitive control ( houde et al . , 2010 ) ] .
the occipito - temporal cortex ( also named the visual word form area or vwfa ) is composed of the fusiform gyrus ( fg ) and has been specifically shown to activate in response to word recognition , but not during non - words or presentation of letters ( cohen and dehaene , 2004 ; cohen et al .
it has been suggested that individuals with rd show lower activation in the left fg during word reading compared to typical readers ( trs ) ( benjamin and gaab , 2012 ) .
, 2008 ; brosnan et al . , 2002 ; gooch et al . , 2011
; helland and asbjornsen , 2000 ) with some specific reports of attention difficulties ( facoetti et al . , 2000 ; shaywitz and shaywitz , 2008 ) .
indeed , the severity of cognitive deficits has been positively correlated with reading impairments ( horowitz - kraus , 2014 ; horowitz - kraus and breznitz , 2013 ) .
these findings suggest that deficits in underlying cognitive abilities such as attention and ef may be related to rd in dyslexia . in the past decade , several neuroimaging studies supported the altered activation of neural circuits supporting ef in individuals with rd and the over - activation in these regions as a strategy of compensating for rd ( pugh et al . , 2000 ;
the authors suggested that at baseline , when children with rd encounter a word that they struggle to decode , the inferior frontal gyrus ( related to semantic abilities ) and the dorsolateral prefrontal cortex ( related to ef ) are employed as compensatory circuits ( see also heim et al . , 2013 for demonstration of this phenomenon in adults ) .
demonet and colleagues also reported a greater activation of frontal regions in children with rd ( specifically of the inferior frontal regions ) compared to trs and suggested that this reflects the compensatory pathways of individuals with rd in different types of phonological processing ( demonet et al . , 2004 ) .
heim and colleagues suggested that the lower level of activation of the ventral - occipital temporal route for words is shared among individuals with rd ( heim et al . , 2013 ) .
other genetic studies also indicated a decreased activation in the dorsolateral prefrontal cortex ( wang , 2014 ) and decreased gray - matter volumes ( black et al .
, 2012 ) in 5 year olds and 4 year olds with a familial risk to develop rd , respectively .
these studies support altered ef abilities as well as the neural circuits supporting ef in individuals with rd , but are lacking a direct examination of the relationship between neural circuits supporting reading , language , and other cognitive domains , such as ef in individuals with rd .
vogel and colleagues suggest that the vwfa is functionally connected with the dorsal attention network in the inferior parietal lobule as determined during resting - state functional magnetic resonance imaging ( fmri ) ( vogel et al .
the precuneus is part of this dorsal attention network and supports visual attention ( vogel et al . , 2014 ) , and
this region is thought to be part of a wider cognitive - control model named the dual - networks top - down model ( dosenbach et al . , 2008 ) .
the first is the rapid adaptive control network that allocates attention to a cue and involves a frontal
the second is the set - maintenance network that maintains task goals , sustains adjustments for feedback control , monitors errors , and involves a cingulo - opercular circuit .
the connectivity within these networks increases throughout development ( dosenbach et al . , 2008 ) .
2015 ) , but only the functional connectivity between the fronto - parietal network and the fg has been positively correlated with reading skill and age ( vogel et al . , 2014 ) .
the authors highlight the role of visual attention in reading and suggest that a deficit in visual attention may contribute to the reading impairments in individuals with rd [ see also lassus - sangosse et al .
, 2008 ; valdois et al . , 2004 ; vidyasagar and pammer , 2010 ] . the role of attention as the basis for memory , ef , and reading outcomes also is supported by behavioral studies ( masur et al . ,
fluent reading depends on accurate , timely decoding of words ( breznitz , 2006 ) .
word decoding relies not only on intact phonology , orthography , and semantics , but also on intact basic cognitive abilities such as attention , speed of processing , and working memory ( which are part of the umbrella term
executive functions ) ( christopher et al . , 2012 ) . the reading acceleration program ( rap ) is an ef - based computerized reading intervention ( breznitz et al . , 2013 ) .
this reading training focuses on language abilities while also exercising the domains of attention , working memory , and speed of processing that support ef .
the rap forces the reader to visually follow letters ( i.e. , attention ) as they are erased from the screen ( i.e. , reliance of working memory ) at a progressively faster speed ( i.e. , speed of processing ) .
monitoring comprehension ensures that the trainees do not only track the letters with their eyes , but that they also keep this information in their memory and process it linguistically .
this procedure forces the reader to process words in a fast , holistic manner and releases the bottleneck in working memory , enabling comprehension ( horowitz - kraus and breznitz , 2013 ) . in turn
, the readers ' ability to read words improves as their mental lexicon becomes more stable and their error monitoring improves ( horowitz - kraus and breznitz , 2013 ; horowitz - kraus et al .
previous studies have shown that improvement in error - monitoring , working memory , and other ef after the rap training is accompanied by greater frontal activation [ inferior frontal gyrus ; brodmann area ( ba ) 44 and anterior cingulate cortex ( acc ) ; ba 24 ] ( horowitz - kraus et al . , 2014b ) .
we also have observed greater functional connectivity between frontal ( ba 24 ) and visual ( fg ; ba 37 ) regions during an fmri reading task after the rap training , suggesting that as the rap forces the reader to read faster and visually attend and track the letters , both ef and attention improve . a recent resting - state functional connectivity analysis in 715 year - old children with rd demonstrated increased functional connectivity between the left vwfa ( ba 37 ) and both frontal regions related to ef ( medial fg ; ba 10 ) and other reading regions ( middle occipital regions ; ba 18,19 ) compared with trs ( koyama et al . , 2013 ) .
studies have demonstrated the possible positive effects of reading training , not only on the activation of reading circuits in individuals with rd , but also on the functional connectivity with other regions related to attention or ef ( horowitz - kraus and breznitz , 2013 ; koyama et al . , 2013 ) .
however , as previously suggested ( price and devlin , 2011 ; vogel et al . , 2013 ) , the human brain is not
tuned specifically to reading , but rather it depends on networks that maintain other functions and also enable reading ( such as visual processing , attention , and language - related regions ) ( vogel et al . , 2013 ) .
therefore , when reading interventions are administered , they may actually target brain regions that are not reading specific .
previous studies ( horowitz - kraus and breznitz , 2013 ; horowitz - kraus et al . ,
2014b ) repeatedly determined that the rap training resulted in greater activation in regions that are specific to visual processing ( i.e. , related to word recognition ) , such as the fg .
however , there are reports of the effect of the rap training on activation of regions that are not specific to reading ( i.e. , attention , ef , working memory , and language ) ( horowitz - kraus and breznitz , 2013 ; horowitz - kraus et al . , 2014b ) .
therefore , our current study aimed to determine the effect of the rap on connectivity among neural circuits supporting both reading and ef / attention in the absence of a stimulus , i.e. , in a resting - state condition , by focusing on the functional connectivity with regions related to visual processing , as reported by other studies related to the effect of the rap training and other studies related to reading ( koyama et al . , 2013 ) . unlike task - based fmri studies , fluctuations in blood - oxygenation - level - dependent ( bold ) signals during a resting - state fmri condition are observed in the absence of an experimental stimulus .
the degree of temporal correlation of these fluctuations between brain regions is thought to reflect interregional functional connectivity .
the current study was designed to answer the following questions : 1 ) what are the changes in functional connectivity between networks supporting reading ( e.g. , visual processing ) and networks related to ef , attention , memory , and language following the rap intervention in either individuals with rd or trs ? 2 ) will connectivity within or between the ef circuits be altered after the rap training during a resting - state condition in either individuals with rd or trs ? to answer these questions ,
children with rd and trs participated in two resting - state fmri scans before and after 4 weeks of training with the rap .
data were analyzed using an independent component analysis ( ica ) approach to extract pertinent functional networks ( components ) .
we hypothesized that children with rd would show increased functional connectivity between the visual processing component and components related to ef , attention , memory , and language after the rap training .
we also hypothesized that automatic reading in trs after training would result in reduced functional connectivity between visual processing and language components [ as observed in vogel et al . ,
we postulated that a specific increase in functional connectivity between the visual processing component and attention and ef components after training would be correlated with greater word reading and comprehension scores in both groups .
children with rd [ n = 18 , mean age = 9.9 years , standard deviation ( sd ) = 1.3 years ; 9 females ] and tr ( n = 18 , mean age = 9.8 years , sd = 1.7 years ; 9 females ) participated in the study .
participant groups were matched for nonverbal iq scores ( mean standard score = 103 , sd = 7.43 ) as measured by the test of nonverbal intelligence , third edition ( toni-3 ; brown and johnsen , 1997 ) .
both reading groups underwent baseline behavioral and neuroimaging assessments followed by 4 weeks of the rap training with follow - up ( behavioral and neuroimaging ) assessments .
all participants were right - handed , native - english speakers with average socioeconomic status , normal or corrected - to - normal vision in both eyes , and normal hearing .
none had a history of neurological or psychiatric disorders , and no differences were found between children with rd and trs in attention ability as measured by the conners questionnaires ( conners , 1989 ; self - report t(36 ) = 1.227 , p > 0.05 and parental report , t(36 ) = 0.249 , p > 0.05 ) .
children with rd either had received a formal diagnosis or presented with parentally reported difficulty with reading , which was confirmed by the study 's reading battery .
reading ability was evaluated using a battery of normative reading tests in english : 1 ) word - reading accuracy / orthography : word - reading efficiency subtest [ test of word reading efficiency ( towre ; torgesen and rashotte , 1999 ) ] ; 2 ) decoding accuracy : decoding subtest for nonwords reading ( towre ; torgesen and rashotte , 1999 ) ; and 3 ) contextual oral - reading fluency : gray oral - reading test ( gort - iv , wiederholt and bryant , 1992 ) .
reading fluency in the gort takes into account both the accuracy and the reading - rate levels , i.e. , when errors are committed it affects the overall fluency score .
children with rd had to reach a standard score of 1 or below ( 25th percentile and below ) in both word reading , decoding , and fluency tests ( i.e. , in all three tests ) .
trs were age - matched students who volunteered for the study and had fluent and accurate reading [ according to norms ; i.e. , reached a standard score of 1.5 ( 90th percentile ) or higher in all reading tests ] as verified using the same tests that were used to evaluate the children with rd . to assess the effect of intervention on behavioral reading measures , we used separate repeated measures analysis of variance ( rm - anova ) utilizing the reading scores for the different reading domains ( i.e. , towre , gort - iv , and reading comprehension and speed as measured by the rap ) .
different forms of these same measures were used after intervention to avoid a priming effect ( the after - intervention assessment was taken approximately 5 weeks after the first training session ) .
the study was carried out in the imaging research center at cincinnati children 's hospital medical center ( cchmc ) , cincinnati , oh . all participants gave their informed written assent and their parents provided informed written consent prior to inclusion in the study , and all were compensated for their participation .
participants were asked to look at a gray cross in the center of a black background on a screen for 5.5 min .
participants performed this scan prior to and following the rap training ( approximately 5 weeks apart ) .
all images were acquired on a philips achieva 3 t mri scanner ( philips medical systems , best , the netherlands ) . a t2 * -weighted , gradient - echo planar imaging ( epi ) sequence was used with fmri parameters : tr / te = 2000/38 ms , matrix size = 64 64 , slice thickness = 5 mm , resulting in a voxel size = 4 4 5 mm . artifacts at this long echo time were minimized using a sense factor of 2 in a 32-channel rf head coil . during the resting - state scan
, 165 whole - head volumes were acquired for a total imaging time of 5.5 min .
in addition , a high - resolution t1-weighted 3d anatomical scan was acquired using an inversion - recovery - prepared turbo gradient - echo acquisition protocol with a spatial resolution of 1 1 1 mm . during image reconstruction , a gradient - echo field
was used to correct for geometric distortion due to b0 field inhomogeneity . reconstructed fmri data for each scanning session
were then pre - processed using spm8 software ( http://www.fil.ion.ucl.ac.uk/spm/ ) , including slice - timing correction , realignment to the first image of the session to correct for motion using 3 translational and 3 rotational parameters , coregistration of the anatomical image to the mean aligned functional image , normalization of all images to the montreal neurological institute ( mni ) template , which was found to be appropriate for children age 5 and above ( altaye et al . , 2008 ) , and spatial smoothing with an 8-mm full width at half - maximum ( fwhm ) gaussian kernel .
following pre - processing , the resting - state data were fed into the ica pipeline .
the pre - processed image volumes from 72 datasets ( 18 datasets each for children with rd and trs , both before and after training ) were submitted to subject - wise group ica implemented in the group ica of fmri toolbox ( gift ; http://mialab.mrn.org/software/gift/index.htm ) ( see fig . 1 for the steps of the analysis ) .
ica is a multivariate data - driven method that does not assume an a priori task - driven hemodynamic response ( calhoun et al . , 2001 ) .
the subject - wise temporal concatenation technique has been shown to produce the best overall performance compared to other proposed methods ( schmithorst and holland , 2004 ) .
using the minimum description length ( mdl ) criterion modified to account for spatial correlation built into the toolbox , we estimated 47 group components for the pre / post - conditions for both participant groups .
the mdl model selection criterion is designed to estimate the optimal dimension of the signal subspace in fmri data before the principal component analysis ( pca ) reduction step ( yourganov et al . , 2010 ) .
pca was then used for dimensionality reduction in a two - stage process to reduce the computational complexity of the ica ( calhoun et al . , 2001 ) .
first , pca was applied to each individual 165-volume dataset to obtain the first 71 principal components .
after temporal concatenation of all datasets , a second application of pca to the concatenated data reduced the dimensionality to 47 principal components , the number estimated by the mdl . following this step , we proceeded with ica using the infomax algorithm ( bell and sejnowski , 1995 ) .
the resulting 47 aggregate group components were then back - projected using the gica3 algorithm ( erhardt et al . , 2011 ) , yielding corresponding individual - subject independent components ( ics ) and time courses .
mean group ics and time courses were then generated across subjects ( fig . 1 ) .
since ica may produce ics representing noise ( e.g. , movement artifact ) in addition to biological signals ( hyvarinen and oja , 2000 ) , a procedure was implemented to identify group ics of interest .
often , independent component time courses are correlated to the time course of a task to identify task - related ics ( karunanayaka et al . , 2011 ; kim et al .
since this resting - state study did not incorporate a specific cognitive task , ics were included or excluded based on visual inspection of their spatial distributions .
exclusion of ics proceeded using two previously published criteria : 1 ) ics residing primarily in white matter , ventricle(s ) , or outside the brain were excluded on the basis that these regions do not generate bold signal ( calhoun et al .
2 ) ics symmetrically distributed over large portions of the brain were excluded on the basis that they do not describe plausible resting - state networks ( kiviniemi et al .
after applying the initial exclusion criteria , we visually searched for the independent component that represents visual processing [ see smith et al . , 2009 for a description of this component ] .
canonical templates may be used to aid in the identification of specific networks , but these have not been shown to make identification more reliable compared to manual network selection ( franco et al . , 2009 ) .
we elected to identify networks manually to avoid inadvertently rejecting valid ics not included in an a priori template .
we then focused on the connectivity between the visual processing component and the remaining included ics ( fig .
1 ) . to test the differences between correlation coefficient values between each pair of ics before and after intervention between the groups
, we performed a 2 2 rm - anova for group ( rd , trs ) and testing time ( test 1 , test 2 ) .
we also compared resting - state network connectivity , defined as the pearson correlation of time courses between pairs of ics , between reading groups ( children with rd and trs ) and within groups between the different conditions [ baseline measures ( test 1 ) and post - intervention measures ( test 2 ) in each group separately ] .
the number of comparisons was limited by designating ic1 ( visual processing component ) as our independent component of interest and considering only the correlations between ic1 and the remaining included ics ( the selection of ics is described in fig . 1 ) .
p - values for each of the seven comparisons of pairwise correlation coefficients between ics were adjusted for multiple comparisons using false discovery rate ( fdr ) .
this correction for multiple comparisons was performed for each of the four experimental conditions separately and thresholded for statistical significance at p - corrected < 0.05 . to relate behavioral reading scores to functional connectivity between the ics
, a pearson correlation was performed between reading measures and functional connectivity of participants at baseline before the rap training ( i.e. , test 1 ) .
to relate the behavioral gains from training to the change in functional connectivity between the ics , we calculated the difference in connectivity before and after the rap training for each pair of components for each participant and performed pearson correlations between the difference in reading measures and the change in functional connectivity .
the rap bank of 1500 sentences was composed of moderate- to high - frequency words in the english language ( http://www.wordfrequency.info/ ) .
each stimulus was a sentence with a multiple - choice question followed by four possible answers .
each sentence was 912 words in length , comprised of 4570 letters with a letter width of 5 mm , extended over 12 lines , and with 18 mm between lines .
the sentences have been tested and verified for their level of difficulty in previous studies in english ( move refs so english first since this study was in english ) ( breznitz , 2006 ) as well as in hebrew ( horowitz - kraus et al .
, 2014a , 2014b , 2014c ; horowitz - kraus and holland , 2015 ) .
reading training was administered via the internet using a computer in each participant 's house .
the primary investigator monitored training by a remote access to the training records . through the administration option of the rap ,
the study personnel monitored the start and end time for each session , making sure that the program was not left unattended during the training session .
the participants were trained for 4 weeks , 5 times each week , 1520 min per session , for a total of 20 sessions , and reading a different set of 50 randomly presented sentences in each session .
the initial and final reading pace and comprehension were measured by the evaluation mode of the rap , which measures these variables in a self - paced reading condition ( breznitz et al . , 2013 ) .
the duration of a sentence on the screen was calculated individually for each participant based on the diagnostic mode ( see the following section ; presentation rate ) .
duration was controlled by text erasure , starting from the beginning of the sentence and advancing at a given per - character rate .
all participants were presented with the same sets of sentences , in the same order .
they were instructed to read the sentence silently and while doing so , the sentence disappeared from the computer screen and a multiple - choice comprehension question with four optional answers appeared and remained on the screen until the participant responded .
they were instructed to choose the correct answer by pushing the corresponding number on the numeric keypad of the computer .
the initial text erasure rate was determined specifically for each participant , based on a pre - test evaluation mode administered prior to training .
the evaluation mode consisted of 12 sentences and 12 multiple - choice questions ( breznitz and leikin , 2000 or breznitz and leikin , 2001 ) .
the mean reading rate ( milliseconds per letter ) for the sentence correctly answered by each participant determined the initial presentation rate of the rap for that participant . in the first training session ,
the letters in each sentence disappeared one after the other , according to the mean reading time ( milliseconds per letter ) recorded on the pre - test . following the disappearance of the sentence from the computer screen , participants were instructed to answer the question at a self - paced rate
the per - letter presentation rate decreased from one sentence to the next in steps of 2% ( breznitz , 1997a , b ) in a staircase - like procedure , and the disappearance rate
increased only when the participants ' answers to the probe questions were correct for 10 consecutive sentences .
the different two - way ( 2 2 ) rm - anovas [ group ( children with rd , trs ) ] [ test ( test 1 , test 2 ) ] revealed greater word and nonword reading scores after intervention in both children with rd and trs with relatively lower reading scores in children with rd as compared to trs ( from the towre , for words and nonwords ) . the same direction of results was observed for the contextual fluency reading as well as reading speed and comprehension conditions : although both reading groups gained from training ( i.e. , a main effect of test ) , children with rd showed a relatively greater increase in reading fluency ( from the gort - iv ) and speed per sentence and comprehension scores ( from the rap ) in test 2 versus test 1 compared to the trs .
of the 47 group ics for all conditions ( i.e. , children with rd in tests 1 and 2 , and trs in tests 1 and 2 ) , eight survived our exclusion criteria , and one ic representing the visual processing independent component ( ic1 ) was selected as the ic to which connectivity was assessed , as shown in fig . 2 .
note that each group aggregate ic map ( shown in figs . 2 and 3 )
was thresholded at 99% of the robust range to generate these figures , where the robust range was defined as the 2nd98th percentiles of voxel intensities within a volume .
rm - anova revealed a main effect of group for ic1ic4 [ f(1,30 ) = 7.586 , p < 0.05 , = 0.202 ] , revealing an overall greater functional connectivity between the visual and sensory
motor ics in children with rd compared to trs ; a main effect of test for ic1ic7 [ f(1,30 ) = 5.548 , p < 0.05 , = 0.156 ] , and ic1ic8 [ f(1,30 ) = 2.689 ,
p < 0.05 , = 0.082 ] was also found , suggesting greater functional connectivity between the visual component and the dorsal attention and memory components following intervention ( test 2 as compared to test 1 ) .
a significant group test interaction was found for ic1ic2 [ f(1,30 ) = 6.275 , p < 0.05 , = 0.173 ] , ic1ic5 [ f(1,30 ) = 5.81 , p < 0.05 , = 0.162 ] , and ic1ic6 [ f(1,30 ) = 4.372 , p < 0.05 , = 0.127 ] demonstrating overall increased correlation coefficient values following intervention in children with rd between the visual component and ef , language , and ot stream components .
the t - test analyses revealed that before intervention , children with rd showed decreased functional connectivity between ic1 ( visual processing component ) and ic2 ( ef component ) and between ic1 ( visual processing component ) and ic3 ( attention component ) as compared to trs .
however , children with rd showed greater functional connectivity between ic1 ( visual processing component ) and ic4 ( sensory motor component ) as compared to trs .
after intervention , children with rd showed greater functional connectivity between ic1 ( visual processing component ) and ic5 ( language component ) as compared to trs . within - subject
paired t - test analysis revealed that after training , children with rd demonstrated greater functional connectivity between ic1 ( visual processing component ) and ic2 ( ef component ) and between ic1 and ics 68 ( occipito - temporal , dorsal attention , and memory components ) , whereas trs showed decreased functional connectivity between ic1 ( visual component ) and ic5 ( language component ) after training ( table 2 ) .
pearson correlation between the behavioral measures before training ( test 1 ) and the connectivity values between pairs of ics before training revealed a significant negative correlation between the connectivity of ic1 ( visual processing component ) and ic4 ( sensory motor component ) and the word and nonword reading scores ( from the towre word recognition subtest : r = 0.526 , p < 0.01 ; and from the towre nonword decoding task : r = 0.499 , p < 0.01 ) .
positive correlations of connectivity between ic1 ( visual processing component ) and ic3 ( attention component ) and between ic1 ( visual processing component ) and ic6 ( occipito - temporal component ) and word - recognition ability also were observed ( although did not reach significance : r = 0.313 , p = 0.07 and r = 0.324 , p = 0.06 , respectively ) .
these results suggest that increases in functional connectivity between the visual component and attention or occipital
temporal components tend to be associated with better word reading at baseline , before reading training .
the correlations between the gain in reading ability ( the difference between reading speed and comprehension in test 1 vs. test 2 , as measured by the rap ) and the change in connectivity after intervention revealed that greater gain in reading comprehension resulted in greater increases in functional connectivity between ic1 ( visual processing component ) and ic2 ( ef component ) in the entire sample ( r = 0.482 , p < 0.001 ) .
the goal of this study was to determine whether the previously found reading improvement following the rap training involves changes in functional connectivity between the visual network ( including the vwfa ) and networks related to ef , attention , memory , and language during the resting - state condition after the training ( in the absence of a task ) . as postulated , our results demonstrate that reading improvement was accompanied by greater functional connectivity between the visual processing component and the attention , ef , and language components in both children with rd and trs . after the rap , trs showed decreased functional connectivity between the visual and language components , which involve frontal regions .
interestingly , the components in which connectivity changes correlated with reading changes share regions that are part of the fronto - parietal or cingulo - opercular networks .
these results suggest that the fronto - parietal network is involved in reading , as has been previously suggested ( dosenbach et al . , 2008 ;
the results also demonstrate the involvement of regions that are part of the cingulo - opercular network ( i.e. , the acc ) , which is supported by the literature indicating the positive effect of the rap training on error monitoring ( evoked from the acc ) in both trs and children with rd ( horowitz - kraus and breznitz , 2013 ) .
in addition , our results confirm the positive effect of the rap training on rewiring neural circuits related to the visual processing , ef , attention , memory , and language regions in individuals with rd ( breznitz et al . , 2013 ;
, 2014a ; horowitz - kraus et al . , 2014b ; niedo et al . ,
2014 ) even in the absence of stimuli ( i.e. , in a resting - state condition ) , which supports our original hypotheses . decreased functional connectivity between the visual processing ( ic1 ) and ef ( ic2 ) and attention ( ic3 ) components in children with rd as compared to trs during rest also has been suggested by koyama and colleagues ( koyama et al . , 2013 ) , as well as by other neuroimaging studies indicating a decreased activation of neural circuits supporting ef in children with rd ( wang , 2014 ; black et al . , 2012 ) .
koyama and colleagues demonstrated weaker functional connections between the inferior parietal lobule and the middle frontal gyrus in children with rd ( koyama et al . , 2013 ) .
based on the dual - networks top - down control model , the inferior parietal lobe ( ba 7 ) and the middle frontal gyrus ( ba 10 ) are part of the fronto - parietal network ( dosenbach et al . , 2008 ) .
this network is particularly important for allocating visual attention during reading ( vogel et al . , 2014 ) .
the activation of the frontal ( inferior frontal gyrus and dorsolateral prefrontal cortex ) and parietal ( precuneus ) regions that are part of this network has been determined to be predictive of proficient reading even before reading ability is completely acquired in 6 year - old children ( horowitz - kraus et al . , 2014c ) .
taken together , these findings support the suggestion that better reading ability is supported by neural networks related to cognitive control , i.e. , the fronto - parietal network [ as was also described by dosenbach et al . , 2008 ; vogel et al . , 2014 ] .
however , a further study should examine the effect of the rap training on a priori - defined regions of interest comprising the fronto - parietal network or using a parcellation approach [ see also power et al . , 2011 ] .
interestingly , in addition to the decreased functional connectivity between the visual and frontal and parietal components , we also found an overall main effect of group as well as an increased functional connectivity between the visual processing ( ic1 ) and sensory motor ( ic4 ; composed of frontal and parietal regions ) components in children with rd compared to trs before training ( i.e. , in test 1 ) .
the sensory motor deficit in individuals with rd related to the magnocellular difficulty in this population was described previously ( ramus , 2003 ; stein , 2001 ; stoodley et al . , 2000 ) .
we suggest that the increased functional connectivity between ic1 and ic4 is linked to the pathology of individuals with rd : slower word and nonword reading .
this is supported by the correlation of the functional connectivity between ic1 and ic4 and slower reading pace ( as measured by the rap ) in this study .
this assumption does not contradict the positive contribution of the fronto - parietal network to the reading process , since the post - central and pre - central gyri that comprise the sensory motor component are not part of the fronto - parietal network ( dosenbach et al . , 2008 ) .
our data , specifically the decreased functional connectivity of the visual processing ( ic1 ) and the attention ( ic3 ) components in children with rd compared to trs before intervention , connect the impairments in attentional and ef processes to difficulties with reading found in children with rd ( facoetti et al .
, 2000 ; horowitz - kraus , 2014 ; shaywitz and shaywitz , 2008 ) .
attention and ef should be allocated to the process of letter selection from irrelevant letters ( bouma , 1970 ; bouma and legein , 1977 ) by rapid orienting of visual attention ( yeshurun and rashal , 2010 ) before the correct letter - to - speech sound integration applies ( facoetti et al .
, 2000 ; hari and renvall , 2001 ; vidyasagar and pammer , 2010 ; zorzi et al . , 2012 ) . ultimately , the next intriguing question is whether a reading training that is ef - based , such as the rap , improves reading through modifying these functional connections .
the current study confirms our hypothesis that greater functional connectivity between the visual processing component ( ic1 ) and components related to cognitive control ( i.e. , ic2ef , ic7dorsal attention , and ic8memory components ) showed an increased functional connectivity after the rap training , in both reading groups ( i.e. , a main effect of test ) .
we also hypothesized that greater functional connectivity would be found between the visual processing ( ic1 ) and ef ( ic2 ) components and dorsal attention ( ic7 ) and memory ( ic8 ) components in children with rd after the rap training , even at rest .
moreover , an increased change in functional connectivity between ic1 ( for visual processing ) and ic2 ( ef ) , ic6 ( ot stream ) , and ic5 ( language ) was found to be significantly greater in the rd group , compared to the trs ( i.e. , a significant interaction ) .
this may explain previous findings showing overall improvements in attention and ef non - linguistic tasks following the rap training ( horowitz - kraus and breznitz , 2013 ) , as well as an overall improvement in the linguistic domain in both children with rd and trs , compared to children with rd who did not train on the rap program ( horowitz - kraus et al .
the greater reliance on frontal regions following acceleration manipulation also has been reported in adult trs ( benjamin and gaab , 2012 ) .
the role of the frontal lobe as a possible compensatory pathway in children with rd by means of semantic retrieval or reliance on ef was previously suggested ( pugh et al . , 2000 ;
the functional regions of the ef and dorsal attention components found in the current study are part of the fronto - parietal network ( dosenbach et al . , 2008 ) .
our results therefore suggest that these sub - regions of the fronto - parietal network , which are involved in rapid adaptive control processes , also are affected by the rap .
previous results from studies of the effect of the rap have suggested that improved reading and ef are related to both better error monitoring ( horowitz - kraus and breznitz , 2014 ) and greater involvement of cognitive - control processes related directly to reading ( horowitz - kraus et al .
in addition to the involvement of parts of the fronto - parietal network ( the first network in the dual - networks top - down control model ) in the significantly increased functional connectivity with the visual processing components ( ic1 ) after training , we also found increased functional connectivity between ic1 and the occipital
temporal components ( ic 6 , which includes the acc ) , as well as the language component ( ic5 , which includes the acc ) , which may be related to a greater involvement of the cingulo - opercular network .
the cingulo - opercular network is the second network in the dual - networks top - down control model and is related to sustained adjustments for feedback control and error monitoring ( dosenbach et al .
interestingly , rather than being autonomous , the two control networks work with each other and also with the cerebellum where error information is both received and sent ( dosenbach et al . , 2008 ) .
in the current study , sub - regions of the cingulo - opercular network were found to be positively correlated with the visual processing components following training with the rap , which confirms our previous findings of greater error - monitoring processes after training ( horowitz - kraus and breznitz , 2013 ) .
the acc plays an important role in error monitoring ( falkenstein et al . , 1991 ) .
the activation of this region in typical developing 6 and 11 year - old children during a verb - generation task was found to be positively correlated with reading at the age of 16 years ( horowitz - kraus et al . , 2014c ) .
the authors suggest that this region may be more active when reading has not been fully mastered , and therefore this process demands a greater monitoring .
we previously demonstrated that training with the rap results in greater activation of the error - monitoring system while performing reading errors , which was positively correlated with reading accuracy and speed in children with rd and trs ( horowitz - kraus and breznitz , 2013 ) .
this was consistent with the greater functional connectivity between the fg ( which is part of the vwfa ) and the acc in children with rd during a lexical decision task after training with the rap . as suggested previously ( breznitz et al . , 2013 ) , the manipulation of the rap involves erasing letters from the screen , which requires several steps : 1 ) the trainees develop a better visual attention allocation , store the phonemes and then the words in memory , and then retrieve them for the comprehension stage : all of which demand better higher - order processes in reading .
2 ) after executing the response ( i.e. , reading the word ) , the trainees need to monitor their performance , which requires a comparison of the desired form of the word ( stored in the mental lexicon ) to the actual read word , and this is done in the process of error monitoring ( horowitz - kraus and breznitz , 2008 ) .
we suggest that the first stage can be represented by the increased functional connectivity between the visual and the ef , attention , and memory components ( all involve regions of the fronto - parietal network ) , which also is supported by the positive correlation we determined between the functional connectivity of the visual processing and the ef components with reading comprehension .
the second stage may involve greater functional connectivity with the occipito - temporal and language components and involves regions that are part of the cingulo - opercular network .
these encouraging findings may lead to examination of the cingulo - opercular network specifically in children with rd and an examination of the functional connectivity of this network with the vwfa after training with the rap . according to our data and in contrast with the children with rd
, trs showed less functional connections between the visual processing ( ic1 ) and language ( ic5 ) components after training .
first , the language component is comprised of the acc , which is part of the cingulo - opercular network . in line with our previous assumption
, it may be that for trs less monitoring is needed and hence , less engagement required for the acc during the reading process after the rap resulting in decreased functional connections of ic1 and ic5 .
this also has been confirmed by the absence of acc activation in trs at the age of 16 ( horowitz - kraus et al . , 2014c ) .
second , previous studies have shown that the lower the starting point is , the higher the gain from the rap training ( horowitz - kraus and breznitz , 2013 ) .
we suggest that for trs , who have intact reading to start with , a longer / more intense intervention is needed to modify the functional connectivity between the visual component and regions participating in the fronto - parietal / cingulo - opercular networks involved in reading .
third , it is possible that since the current task is a resting - state condition , the executive - control process specifically for reading did not show as much change in trs as in children with rd .
future studies using region of interest - based analysis focusing on reading and ef - related seeds or a data - driven parcellation method [ see power et al . ,
the results of the current study should be evaluated taking into account the following limitations .
first , the results represent the data from a resting - state condition and , despite the correlation analysis with behavioral measures , do not reflect the actual participating components in the reading process .
a future study should examine the correlations between the visual and ef and attention components after training with the rap during a reading task .
second , since our results showed that the visual component was correlated with components that are composed of regions that are parts of networks from the dual - networks top - down control model , we have discussed the results in the context of the fronto - parietal and cingulo - opercular networks .
however , it is important to note that since the main aim of the study was to examine the effect of the rap training on the functional connections between the visual component and other components related to cognitive control and language , we were not focused on these cognitive - control networks specifically . to validate our interpretation , a region - of - interest analysis
should be carried out using an a priori selection of the functional regions participating in the model .
a further analysis should examine the functional connectivity of each of the voxels in the vwfa with the cingulo - opercular and fronto - parietal networks as has been done previously ( greene et al . , 2014 ) .
third , fdr correction was used to correct for multiple comparisons when considering differences in pairwise correlations between ics within each experimental condition .
seven ics being compared to an eighth ic equals 7 comparisons within each condition , times 4 experimental conditions equals 28 total comparisons . since fdr was performed separately within each condition and not across all 28 comparisons , the reported corrected p values are smaller than they would be had fdr been performed across all 28 comparisons .
lastly , we selected an acquisition time of 5.5 min to facilitate compliance of our pediatric study population and minimize motion artifacts .
future studies might increase statistical power by increasing the acquisition time or concatenating several resting - state acquisitions . in conclusion ,
the current study indicates that the rap , an intervention designed to improve reading performance in children with rd , is associated with changes in connectivity in ef , attention , memory , and language resting - state components that correlate with improvement in reading performance .
the observation of changes in functional connectivity between these components and the visual - processing component , even in the absence of a linguistic task ( i.e. , at rest ) suggests that the rap has an effect on basic cognitive domains that can be detected even in the absence of a reading task .
therefore , two clinical implications should be considered : 1 ) special attention should be given to ef , attention , and memory domains during diagnosis of children with rd .
2 ) reading intervention programs should include an attention / ef / memory component in order to train these abilities as part of reading remediation .
Output:
| the reading acceleration program , a computerized reading - training program , increases activation in neural circuits related to reading .
we examined the effect of the training on the functional connectivity between independent components related to visual processing , executive functions , attention , memory , and language during rest after the training .
children 812 years old with reading difficulties and typical readers participated in the study . behavioral testing and functional magnetic resonance imaging were performed before and after the training .
imaging data were analyzed using an independent component analysis approach .
after training , both reading groups showed increased single - word contextual reading and reading comprehension scores .
greater positive correlations between the visual - processing component and the executive functions , attention , memory , or language components were found after training in children with reading difficulties .
training - related increases in connectivity between the visual and attention components and between the visual and executive function components were positively correlated with increased word reading and reading comprehension , respectively .
our findings suggest that the effect of the reading acceleration program on basic cognitive domains can be detected even in the absence of an ongoing reading task . |
PubmedSumm118681 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: the replacement of missing teeth with endosseous implants for the rehabilitation of edentulous or partially edentulous patients has become a standard of care in the past two decades . to achieve and maintain osseointegration ,
indications and contraindications must be carefully balanced , and proper patient selection is a key issue in treatment planning . osseointegrated dental implants have a long - term success rate of over 90% , but may be threatened by peri - implant mucositis and peri - implantitis , bacteria biofilm - induced inflammatory conditions .
a number of risk indicators were identified including poor oral hygiene , a history of periodontitis , diabetes and smoking [ 2 - 4 ] .
both of them are initiated by the accumulation of microbial biofilms on hard surfaces that is teeth or dental implants .
systemic diseases may impair the host s barrier function and immune defence against periodontal pathogens creating the opportunity for destructive periodontal disease and likely peri - implantitis .
systemic diseases and medications or other therapies used in their treatment may also interfere healing by influencing the host tissues and physiology , thus increasing the risk of early and late failures of implants .
buser et al . proposed to subdivide risky diseases for implant therapy success into two groups with high risk for patients with serious systemic diseases ( rheumatoid arthritis , osteomalacia , osteogenesis imperfecta , immunocompromising diseases ) or alcoholism , and significant risk for patients with irradiated bone , severe diabetes mellitus , bleeding disorders or heavy smoking habits .
although clinically relevant impact of the most common systemic diseases on the success of implant therapy has been suggested , however there is limited information on the association between implant success and systemic diseases and what type of evidence these statements are based .
the aim of present systematic review was to assess the influence of systemic diseases or medications used for the treatment of systemic disease , on the dental implant therapy success .
protocol and registration the methods of the analysis , inclusion and exclusion criteria were specied in advance and documented in a protocol . the review was registered in prospero , an international prospective register of systematic reviews .
the reporting of this systematic analysis adhered to the prisma ( preferred reporting item for systematic review and meta - analyses ) statement .
the following review question was developed according to the population , intervention , comparison , and outcome ( pico ) study design : what is the risk level for implant failure or peri - implantitis in patients undergoing implant treatment with a history of scleroderma , sjgren s syndrome , neuropsychiatric disorders / parkinsons disease , oral lichen planus , hiv infection , ectodermal dysplasia , long - term immunosuppression after organ transplantation , cardiovascular disease , crohn disease , diabetes , osteoporosis , medication with oral bisphosphonates , or xerostomia ?
a search was implemented on the national library of medicine database ( medline ) ( ovid ) and embase databases based on the search strategy described further .
in the first stage , a title screening took place to exclude all irrelevant publications , case reports , reviews , and animal studies . in the second stage
, the abstracts were read to see if the aim of the study met the systematic review questions .
the third stage was reading full - text articles to confirm each study s eligibility , according to the inclusion and exclusion criteria .
the search was conducted including studies between january 2006 and january 2016 to ensure sufficient and large enough amount of included studies . the following search strategy using keywords : oral implant or
oral bisphosphonates or bisphosphonates or diabetes mellitus or insulin therapy or glucose intolerance or rheumatoid arthritis or aids or hiv or scleroderma or
neuropsychiatric disorders or parkinson or ectodermal dysplasia or crohns disease or transplantation or cardiovascular or
this search for papers was intended for high initial numbers rather than highly specific and strictly rejected in the first instance .
additional studies were screened by scanning the references cited in the retained papers and by personal communication .
only accepted abstracts were then discussed through all three authors . at the full - text reading stage
types of publications the review included all human studies and case reports series published in english .
present review included all retrospective and prospective follow - up studies , case - control studies , case report series and cohort studies published between january 2006 and january 2016 , evaluating the relationship between implant treatment success and at least one systemic disease .
types of participants / population the subjects in the included studies should have been implantation patients who were diagnosed with any systemic disease that may affect implant treatment outcomes .
authors of present review selected possibly relevant diseases that may affect the success of implantation .
it was decided that successful implantation should be , when implants were stable and osseointegrated without any signs of critical complications .
inclusion and exclusion criteria all the included studies should have followed the inclusion criteria listed below : human subjects with the respective diagnosis ; subjects with osseointegrated dental implants or implant placement ; reports of implant failure , survival , and/or success or peri - implantitis ; case series including at least ten subjects with the respective diagnosis .
if case reports with fewer treated subjects were the only available source of information , they were listed ; articles available in english .
following exclusion criteria were applied to all review studies : subjects not uniformed with the diagnosis ; uniformed implantation procedure , whether bone augmentation , sinus lift or other additional procedures are included , or implants solely ; smokers , bad oral hygiene , immediate loading , immediate placement .
sequential search strategy on the first stage of research , same filters were added to every independent disease search : human studies , articles available , 10 years . on the initial search
following the abstract reading stage , inclusion and exclusion criteria were applied to the information given in abstracts , is any information was missing the full - text reading was performed . at the final stage ,
all the included articles were carefully screened and only relevant articles were included for further analysis . all included studies were arranged according to following fields :
implantation type - described weather the immediate implantation post - extraction , sinus lift , bone augmentation etc . were applied to included patients .
number of implants - showed the amount of implants analysed in studies . year of follow - up - described the mean , minimum and maximum follow - up time periods applied to subjects .
disease severity or medication dose level - was used to evaluate the disease s severity or medication dose level and type of consumption to reveal if these factors affect the success of implantation .
disease manifestations according to the implantation - showed , weather the time ( post and pre - operative ) of disease manifestation affected the implantation success .
risk of bias assessment the quality of all included studies was evaluating during the full text reading stage . to assess the risk of bias in every study the cochrane collaboration s two - part tool was used .
if any uncertainties were found in studies , the decision was made through the discussion between all the authors .
all the articles were individually evaluated to assess the risk of bias in random sequence generation , allocation concealment , blinding of participants and practitioners , blinding of outcomes assessment , incomplete outcomes data , selective reporting and other sources of bias .
, if any uncertainties were found , high risk of bias if study showed bias in selected category and unclear risk of bias if the methodology was not clearly stated and the risk remained questionable .
if at least one category was rated as high risk of bias or unclear risk of bias , the study itself is rated as high risk of bias or unclear risk of bias respectively .
all the retrospective studies were rated with appreciation that not all the factors , that may affect the bias , could have been controlled by authors , since information of previously performed procedures was collected .
a meta - analysis integrates the quantitative findings from separate but similar studies , and it allows evaluation of the numerical results of the overall effect of interest .
all meta - analysis were performed on studies reporting comparable outcomes . however , most studies could not be compared due to methodological heterogeneity and presented results dispersion .
the data was analysed with a student t - test , 95% confidence interval ( ci ) was calculated where possible . to evaluate the degree of agreement between authors , index was used .
the screening of article titles and independent screening of abstracts resulted in 721 possibly included articles .
a total of 41 articles that met the inclusion criteria were selected for systematic review [ 14 - 54 ] .
the values for inter - reviewer agreement for potentially relevant articles were 1 ( titles and abstracts ) and > 0.9 ( full - text articles ) , indicating an almost perfect agreement between the 2 reviewers . at the full text reading stage , in total 41 articles
the reasons of exclusion were as follows : review papers ( n = 8) , single case reports ( n = 18 ) , methodological and design faults ( n = 15 ) .
mostly exclusion should be provided due to the inadequate articles filtering at the first study selection stage .
study characteristics in total 16 prospective studies [ 14,18,19,28,35 - 40,44,45,47,48,50,53 ] from which 5 were controlled clinical trials [ 38 - 40,44,48 ] and 1 cross - sectional study , 23 retrospective studies [ 15 - 17,20,23 - 27,29 - 34,41 - 43,46,49,51,52,54 ] and two case series studies were included in present research . in total 6813 patients and 19332 implants were screened in included studies . however , in few articles number of implants was not listed [ 18,27,47,51 - 53 ] . the follow - up mean period varied from 9 weeks up to 10 years . however , in few studies follow - up period was not listed due to methodological differences . the implantation success ratio ranged between 100% and 73% on patients and between 100% and 82.6% on implants .
however , these results should be interpreted carefully , since very wide follow - up period gap was seen in included studies .
all studies were classified according to the disease as a risk factor to implant treatment type .
19 articles evaluated osteoporosis and/or bisphosphonate ( bp ) therapy effect [ 14 - 32 ] , in six studies diabetes mellitus was analysed [ 33 - 38 ] .
five articles were based on cardiovascular influence evaluation [ 47,51 - 54 ] , three authors reported the relation between implantation success and rheumatoid arthritis [ 41 - 43 ] . in two studies the effect of hiv was analysed .
one by one articles were included in evaluating the effect of following diseases and stages : crohns disease , sjgren s syndrome , ectodermal dysplasia and immunosuppression after transplantation .
risk of bias within the studies in total 13 studies were considered as low risk of bias , since all the categories in cochrane collaboration s two - part tool were carried out with low possibility of bias .
17 articles were decided to be high risk of bias due to methodological uncertainties .
most discrepancies were found in study sample selection and allocation processes ( table 1 ) .
risk of bias across the studies some of the limitations may be found in this review that may influence the outcomes . in present review
also , studies with small sample sizes were excluded , same as case reports . also , high heterogeneity across the studies was seen . while most of the studies were retrospective , evaluating the broad period results , even prospective studies showed great methodological differences .
some studies measured the implantation results in patients with systemic diseases with results , provided from healthy participants , while other studies presented only systemic disease affected patients or those with complications . while some rare but severe complications were measured across the studies ( e.g. bisphosphonate related osteonecrosis of the jaws [ bronj ] ) we have missed concrete risk rating in most of the studies .
effect of various diseases on implantation outcomes osteoporosis and bisphosphonates treatment out of 4 studies , evaluating only osteoporosis as a risk factor to implantation success , none of them showed significant differences ( table 2 ) [ 14 - 17 ] .
the basic information from articles , evaluating osteoporosis influence on implantation success
bmd - t = bone mineral density test .
study noted that the sample size was not enough to find any statistically significant differences to evaluate the effect of teriparatide .
three other studies [ 15 - 17 ] did not find any significant differences for implantation success neither for osseointegration quality between osteoporotic and control groups .
holahan et al . found that osteoporosis did not show any correlation to local jaw bone quality , but when it was , set subjectively by surgeon , it highly correlated with implantation success ( p < 0.01 ) .
it should be noted that mozzati et al . combined many different implantation methods , such as immediate function loading , immediate implantation and sinus lifting .
also , patients with various risk factors , including diabetes mellitus , smoking , corticosteroid users , oral bp users , were combined in this study . totally different from all others in methodology , was shibli et al .
there were no statistically significant differences found between osteoporotic and control patients groups , according to the bone to implant contact ( 46 [ sd 11.46]% vs. 47.84 [ sd 14.03]% respectively )
. however , alsaadi et al . reported significant correlation between the osteoporosis and implant failure ( p = 0.001 ) .
bronj as a severe complication , which could be provoked because of the implantation , was examined in various studies ( table 3 ) .
two main methodological groups could be concluded - studies , evaluating the bronj among implantation patients , and studies , evaluating the effect of implantation between bronj patients , presenting different outcomes .
the basic information from articles , evaluating bisphosphonates influence on implantation success
bp = bisphosphonate .
results from studies evaluating the percentage of bronj between osteoporotic , bp using
authors that evaluated the implantation influence in bp users among the patients with bronj showed conflicting results .
four authors stated that implantation may induce the start of bronj in bp patients . however , lazarovici et al .
stated , that surgical procedure is not a trigger for the bronj onset , since most bronj are late complications after implantation .
all authors stated that bronj could be present even if the bp treatment is started after the full implants osseointegration and usually comes as late complication , which onsets after 20.9 months to 35 months .
bp effect to the implantation success did not show any statistically significant differences in various studies .
however , zahid et al . showed high correlation between the bp usage and implant thread exposure ( p = 0.001 ) among the 51 implants .
. found , that oral bp may cause various peri - implant complications ( p = 0.001 ) .
pilot study showed the effect of aledronate to bone mineral density . despite the small sample size ( n = 10 ) , placebo - drug trial revealed that aledronate interferes bone remodelling in drug using period . decreasing
bone mineral density was present in results , during the alendronate intake , but 6 months after the end of drugs usage the bone mineral density rebounded .
nevertheless this was only a pilot study ; the bp effect to the bone stronger or weaker - is clearly present .
half of the authors did not find any significant correlations between the presence of diabetes mellitus and implantation success ( table 4 ) . on the contrary , dowell et al .
did not find any evidence of lower implantation success in poorly controlled patients . in one study exclusively only poorly controlled diabetes mellitus patients
were included a despite some complications ( soft tissues inflammation , implant rotation , pain during the healing abutment application ) were observed , at all 98% successes was reached .
the basic information from articles , evaluating diabetes mellitus influence on implantation success
dm+ = diabetes mellitus patients ; dm- = diabetes mellitus free ; hba1c = glycated haemoglobin ; sla / modsla = specific implant type , reported by author .
oates et al . found that osseointegration during the first 4 months postoperatively was poor in people with higher hba1c levels .
only 57.1% implants of poorly controlled diabetes mellitus returned to exceeded baseline stability level after 16 week , compared with 80% in well - controlled group .
study , where statistically significant correlations between hba1c levels and peri - implantitis ( p = 0.05 ) or peri - implant bone loss ( p = 0.01 ) were observed . the higher risk of implantation in diabetes mellitus patients was mentioned in all the studies , despite the positive outcomes [ 33 - 38 ] .
however , there were no differences in implant success among the groups with hiv- or hiv+ .
three studies were enrolled to show the influence of rheumatoid arthritis on implant treatment success [ 41 - 43 ] .
none of the authors found significant correlations between the rheumatoid arthritis and implantation success [ 41 - 43 ] .
however , one author stated that the crestal bone resorption and bleeding on probing was higher in patients with rheumatoid arthritis .
three studies with the different study type and follow - up periods were analysed to evaluate influence of oral lichen planus ( olp ) on the of peri - implant complications [ 44 - 46 ] .
authors of all studies concluded that success of implant rehabilitation among treated olp patients does not differ from the success rate in the general population .
only one prospective study included in the review shows statistically significant crohn s disease s effect on early implant failures .
however evidence level is limited as this study included 11 patients with the 6 months follow - up .
immunosuppression after organ transplantation one prospective controlled study was included that shows effect of immunosuppressive therapy on the patient s that undergo organ transplantation . despite small sample size of 10 patients and 20 implants with the follow - up three months , montebugnoli et al .
concluded that the bone response around submerged dental implants in immunocompromised organ transplant patients does not differ from that observed in control patients and no rejection of implants was noticed .
one retrospective study was identified that shows success of implantation in 50 patients group with sjgren s syndrome .
although patients showed more signs of peri - implant mucositis , korfage et al .
stated this clinically irrelevant , and after median follow - up of 3.8 years prevalence of peri - implantitis was 11% which is comparable with healthy patients .
there is some caution with regard to the potentially increased risk on peri - implantitis in the long term .
the short - term survival data supports successful placing of dental implants in patients with ectodermal dysplasia and congenitally missing teeth with appropriate precautions in the maxilla .
although the age of these patients ranged from 8 to 68 years , there was no significant difference in survival of implants among patient age groups .
the difference in the survival rates of implants placed in anterior mandible ( 9% ) and maxilla ( 23% ) approached significance .
cardiovascular diseases all five studies included to assess impact of cardiovascular diseases ( cvd ) on implantation outcomes are dealing with several correlative factors ( other systemic diseases , smoking , periodontitis ) and cvd are among them [ 47,51 - 54 ] .
. in short term study concluded that tendency for early failures wasnt noticed for cvd or hypertension .
de souza et al . investigated 189 patients with cvd and hypertension out of 253 individuals that had previously attended the supportive periodontal program , to assess the impact of local and systemic factors on additional bone loss ( abl > 2 mm according to the x - ray ) .
analysis included former chronic periodontitis diagnosis ; smoking and local factors and confirmed that cvd are not associated with additional bone loss .
. in retrospective study found that late implant loss was not correlating with cvd and hypertension . on the contrary ,
results of two studies out of five state that patients with cvd showed increased peri - implant bone loss and periimplantitis is associated with cvd .
. revealed that patients with cvd ( n = 19 ) show significantly increased peri - implant marginal bone loss for 4 implant supported mandibular full arch restorations .
however study investigated small sample of cardiac patients including smokers and assessed marginal bone loss only , there is no data published on the success rate of implants .
a history of cvd was found in 27.3% if individuals with peri - implantitis and in 3% of individuals in the implant health / peri - implant mucositis group .
the present study assessed data on radiographic bone levels and concluded that peri - implantitis is a high likelihood of comorbidity expressed by a history of cvd and periodontitis .
in present review we have established only few systemic diseases that were approved by several authors to significantly affect implant treatment success .
most studies were based on evaluating the relationship between the osteoporosis and its treatment influence on implantation success .
osteoporosis is a systemic bone disorder , which is related with the loss of internal structure loss in bone s architecture , lower bone mass and micro and macro bone changes .
there are several different osteoporosis aetiology theories , asserting the lack of oestrogen , calcium circulation disorders , thyroid dysfunction as main causing factor . due to the demonstrated effect of oestrogen insufficiency , in many studies
however , in none of the studies laboratorial hormonal examinations were performed , only stating that post - menopausal women are in higher risk for osteoporosis without individual examinations . despite the pathogenic osteoporosis effect to the bone , holahan et al .
did not find any significant relationships between the osteoporosis and local bone mineral density in jaws .
most authors stated that there arent any statistically significant correlations between the osteoporosis and implantation success [ 14 - 17 ] .
however , it should be mentioned , that bp , the mostly used in osteoporosis treatment , may show some different results .
the main working mechanism is based on suppression of both : bone remodelling and osteoclastic activity , and support of stable structure .
however , rare , but severe side effects are known due to use of bp , such as osteonecrosis of jaws , which usually arise in cancer patients with high bp doses undergoing invasive dental procedures . also , bone healing is usually prolonged in bp treated patients because of bone remodelling suppression .
while in present review half of the authors stated , that the connection between bronj and implantation is not statistically significant , the other half of the articles showed that bronj may appear not only as implantation triggered procedure , but even after the full implants osseointegration , when treatment with bp starts .
these differences , in present authors opinion , appeared due to the methodological and included subjects differences .
while the bronj among all implantation patients , undertaking bp , is rare , from those with bronj , the implantation as possible causative factor is more likely to be . in five studies
any negative bp effect to implantation was declined , but two authors stated , that the risk of peri - implant lesions is higher in patients undertaking bp .
even if aledronates and risedronates are the first line medicine used in osteoporosis treatment , aledronate was found to be the most correlated bp with implant failures .
most authors did not find the negative diabetes mellitus effect to the implantation outcomes , even in poorly controlled diabetes mellitus patients .
however , world health organization states that hba1c monitoring is not a suitable test to measure intermediate hyperglycaemia .
hba1c shows mean plasma glucose levels of past several weeks , so this method should be used to assess the control of present diabetes mellitus , not the disease itself .
nevertheless , tawil et al . found statistically significant relationship between the plasma hba1c levels and peri - implant lesions .
also , prolonged healing was found in non - well - controlled diabetes mellitus patients .
this is not surprising , since generally wound healing is prolonged in diabetes mellitus patients due to the lack of growth factors , impaired macrophage function , collagen accumulation , keratinocytes and fibroblasts migration processes . also , angiogenesis is poor in diabetes mellitus patients , which could be critical factor in voluminous surgical procedures .
rheumatoid arthritis is complex systemic disease and the main mechanism is associated with autoimmune reactions that cause a destruction of articulatory systems .
multiple cytokines play important role in promoting synovial inflammations , that later proceed to destructive process .
[ 63 - 65 ] bone destruction process is caused because of high osteoclastic activity , induced by inflammatory mediators and macrophages that are present in rheumatoid arthritis synovitis however , despite these mechanisms , none of the authors found correlations with implantation treatment failures [ 41 - 43 ] .
. stated that crestal bone resorption and bleeding after the probing was higher in rheumatoid arthritis patients .
this might be due to the low disease expression to the implantation sites , or due to the methodological causes . to resolve this question ,
olp is one of the most common chronic inammatory autoimmune diseases that involve the oral mucosa with an incidence of 1 - 2% in various populations .
possible risks of dental implant placement in erosive olp were suggested by lekholm who hypothesised an increased risk of failure due to the altered capability of the epithelium to adhere to the implant surface . however according to this review success of implant rehabilitation among treated olp patients does not differ from the success rate in the general population [ 44 - 46 ] and implant placement didnt influence olp manifestation .
a careful oral hygiene and frequent follow - up are the main recommendations in olp patients rehabilitated with implants .
with caution due to the level of scientific evidence of the analysed studies , olp does not influence the success of dental implant therapy .
evidence for implantation outcomes in patients with crohns disease , sjgrens syndrome , ectodermal dysplasia and immunosuppressive state after transplantation due to the single publications , small sample sizes , short term follow - up is very low .
crohns disease as an autoimmune disease , affects host response , gastro - intestinal system and leads to periodontal lesions , osseointegration failures .
crohns disease may negatively influence osseointegration success , still further studies are needed to provide these findings .
immunosuppressive treatment that follows organ transplantation may have negative effect on the bone mineral metabolism .
however single study of montebugnoli et al . indicated absence of early complications and showed that the bone response around submerged dental implants in immunocompromised organ transplant patients does not differ from that observed in control patients .
the same was found with human immunodeficiency virus evaluation , since both studies evaluating hiv effect on implantation success did not show any evidence of negative effect to the procedure outcomes outcome of dental implants in patients with sjgrens syndrome and ectodermal dysplasia seem comparable to those of healthy patients , but further clinical investigations including control groups with healthy patients with longer follow - up are needed to clear provided information .
this may have influence the outcome of osseointegration and induce crestal bone level changes over the time .
results of two studies out of five [ 47,51 - 54 ] state that patients with cvd showed increased peri - implant bone loss and periimplantitis is associated with cvd .
regression analysis might be an answer in a population with multiple diseases , study by alsaadi et al .
states that systemic health factors do not seem to be prominent players in the aetiology of late implant loss . however , mombelli and cionca in the review study , considered the fact that potential risk factors , particularly those found more frequently in older adults in general systemic chronic diseases , smoking , periodontitis history , medications , reduced salivary flow may not be independent of each other . one single factor alone may not influence the risk measurably , while a combination of multiple , independent factors may have a significant impact . other limitations of these studies which might explain their controversy , are heterogeneous data structure , some of them are unavailable as cardiovascular patients consisted only part of whole sample ; no data published on the success rate of implants ; implants with different surfaces included .
radiographic examination of additional bone loss has limitation due to the fact that it is performed only in two dimensions , which is not possible to examine buccal and oral sites .
influence of systemic health problems to peri - implantitis requires additional epidemiologic and clinical investigations . for higher state of evidence randomized
controlled clinical trials with included at least 10 patients per condition , more than 1 year of follow - up after implant loading , and the homogeneous criteria ( probing pocket depth , bleeding on probing and/or pus , marginal bone loss ) to define peri - implantitis . in present review we have faced some limitations , due to the high risk of bias assessed in various articles . most included studies were retrospective , which could not give the full information about the implantation procedure implementation and possible risk of bias , reached before the evaluation process .
also , because those only english articles were included , some data could be missing .
implantation in bisphosphonate users may result in rare but severe osteonecrosis complication , regardless of the time of bisphosphonate treatment start - prior or post implantation .
diabetes mellitus is still controversially assessed in different studies ; however it is clearly characterized as a factor encumbering implantation post - operative healing process .
oral lichen planus and rheumatoid arthritis was rated only in few studies , nevertheless no effect of these diseases to implantation success was found .
evidence level of implantation success in hiv / aids is limited due to few studies with short follow - up and small sample sizes , in which no effect to implantation was found .
influence of cardiovascular diseases on dental implantation success should be explored deeply , since controversial results were assessed . for higher state of evidence detailed
randomized controlled clinical trials with homogeneous criteria are needed . to clarify the effect of crohn s disease to implantation success ,
more studies are needed , since only one prospective study with unclear risk of bias and small sample size was found with no evidence of crohn s disease negative influence on implantation outcomes .
sjgren s syndrome , immunosuppressive state after transplantation and ectodermal dysplasia are rather non - related with implantation therapy success , but due to the single publications , small sample sizes , short term follow - up and possible risk of bias these evidences for implantation outcomes are very low .
clear and homogenous methodology is needed since heterogeneous studies outcomes comparison is complicated and not highly reliable . in studies , including patients with multiple diseases , possible co - effect of various diseases should also be reflected before excluding single disorders .
there were no studies evaluating xerostomia and neuropsychiatric disorders , such as parkinson s disease , impact on implantation success that met present review inclusion criteria .
authors would like to give acknowledgments to all the people that help in assessing the articles in interest , without any authorship .
Output:
| abstractobjectivesto systematically review the influence of systemic diseases or medications used in their treatment on the dental implant therapy success.material and methodsthe search strategy was implemented on the national library of medicine database ( medline ) ( ovid ) and embase electronic databases between january 2006 and january 2016 .
human studies with available english articles analysing the relationship between dental implant therapy success and systemic diseases , such as diabetes mellitus , aids / hiv , rheumatoid arthritis , osteoporosis , crohn s disease , cardiovascular diseases , scleroderma , sjgren s syndrome , lichen planus , ectodermal dysplasia , post - transplantation status , were included in present review according to the prisma guidelines .
the review protocol was registered on prospero system with the code crd42016033662.resultspresent review included forty one retrospective and prospective follow - up studies , case - control studies , case report series and cohort studies . despite some limitations this study reveals positive results of implantation in most systemic conditions that should be interpreted with caution .
influence of cardiovascular diseases on the dental implantation success should be explored deeply , because of controversial results and likelihood of comorbidity expressed by a history of cardiovascular diseases and periodontitis .
there is only a weak relationship with bone density in osteoporosis and implant failure .
all the other diseases did not show significant effect on implantation success.conclusionsrecent studies with low strength of evidence and controversy show that systemic diseases may have potential effect on the success of implantation , but further detailed studies are needed to provide these findings . |
PubmedSumm118682 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: myxedema coma is a rare life - threatening complication of long - standing , neglected hypothyroidism . till date
we are reporting the case of an elderly lady with life - threatening myxedema coma and septicemic shock who was successfully treated with oral thyroxine .
a 61-year - old lady , known case of hypothyroidism for 20 years , was admitted in surgical emergency with complaints of abdominal pain and distension for 3 days .
her pulse rate ( pr ) was 68/min . , blood pressure ( bp ) 140/86 mmhg , temperature 36.5c , respiratory rate ( rr ) 10/min .
her investigations were hb -8.8 gm% , total leucocyte count-12,400/mm , serum na-112 meq / l ( normal range 135 - 145 meq / l ) , serum k-2.2 meq / l ( normal range 3.5 - 5.5
her liver function tests , kidney function tests and chest x - ray were normal and ecg showed low voltage complexes .
abdominal ultrasound revealed a mass in right iliac fossa suggesting appendicular lump along with paralytic ileus .
meanwhile her tft showed severe hypothyroidism with t3 being 62 ng / dl ( normal range 100 - 180 ng/ dl ) , t4 - 2.2 g / dl ( normal range 4 - 12 g / dl ) and tsh-18 u/ ml ( normal range 0.5 - 6 u / ml ) . her dose of eltroxin was elevated to 100 g / day .
her abdominal distension increased over the next 48 hours and a contrast - enhanced ct scan of abdomen revealed intestinal perforation .
general anesthesia was induced using rapid sequence induction . immediately after induction , she had systolic hypotension ( 85 mmhg ) , managed with fast crystalloids
. there was a further drop in her blood pressure after the abdomen was opened during surgery , necessitating dopamine infusion along with noradrenaline infusion .
surgery lasted for 2 hours and she was shifted to icu for elective ventilation when received in icu , patient was hypothermic ( temperature 34.6c ) and hypotensive ( systolic bp-68 mmhg ) . rewarming was started with of warm fluids , bladder lavage with warm saline and electric blanket .
three litres of lactated ringer 's solution was pushed intravenously . adrenaline infusion was now added .
unfortunately parental thyroxine was not available so we decided to give eltroxine tablet ( 500 g ) once daily via ryle 's tube .
this along with aggressive antibiotic coverage , steroid supplementation and inotropic support gradually improved her blood pressure over the next 24 hours .
her eltroxine was titrated to 150 g twice a day now . over the next 2 days
finally on postoperative day 5 , she was extubated and shifted to the postoperative ward .
myxedema coma is an extreme complication of hypothyroidism in which patients exhibit multiple organ abnormalities and progressive mental deterioration .
it occurs almost exclusively in age group 60 years and above , with 80% preponderance in females , as seen in our patient .
more than 80% of cases of myxedema coma occur in winters , probably due to age - related loss of ability to sense temperature and lower production secondary to hypothyroidism .
other events which can precipitate it include infections , cardiovascular accidents , congestive cardiac failure and certain drugs .
we presume that in our patient the precipitating factors included winter season , septicemia and stress of surgery and anesthesia .
myxedema coma causes drastic decrease in metabolic rate , hypoventilation , hypotension , hypothermia , decreased mental state progressing to coma and decreased cardiac output .
a common misconception is that a patient must be comatosed to be diagnosed with myxedema coma .
although we could not get cortisol level determined , empirical steroid supplementation aided in the recovery of our patient .
even with optimum therapy , mortality rate as high as 30 - 60% has been reported .
did a study to determine the various predictors of outcome in myxedema coma and concluded that various factors associated with increased mortality included bradycardia , need for mechanical ventilation , hypothermia , sepsis , hypotension and intake of sedative drugs . in our patient
most of these factors were present but were managed aggressively and judiciously . in literature , intravenous thyroid hormone supplementation has been advised for the treatment of myxedema coma but since it was not available , early supplementation of a higher dose ( 500 g / day ) of oral thyroxine was started via the ryle 's tube .
the good outcome of our patient despite severe hypothyroidism and septicemic shock with gangrene occurred most probably due to the fact that she was already receiving eltroxine , though suboptimal dose and our aggressive inotrope therapy , fluid management and multiple antibiotics .
to conclude , the combination of myxedema coma and sepsis in a patient can be lethal .
early institution of thyroxine supplementation , even via oral route , along with inotropic support and steroid supplementation , can improve the prognosis .
Output:
| myxedema coma is a life - threatening but uncommon complication of long - standing , neglected hypothyroidism .
it was first reported by ord in 1879 . till date
only around 200 cases have been reported in literature .
the incidence in european countries is 0.22 per million per year .
no epidemiological data is available from the indian subcontinent .
we are reporting the case of an elderly lady who went into life - threatening myxedema coma along with septicemic shock , and was successfully treated with oral thyroxine . |
PubmedSumm118683 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: the incidence of diabetes in the world is showing an increasing trend with each passing day . the therapeutic approach to type 2 diabetes mellitus usually commences with a single hypoglycemic agent , which most of the times , is metformin , a biguanide .
metformin activates adenosine monophosphate ( amp)-dependent protein kinase and enters cells through organic cation transporters .
metformin is the drug of choice because it not only reduces serum glucose but also improves lipid profile and brings about modest weight loss . however , there are several disadvantages to the use of metformin , the one which the present study discusses is vitamin b12 deficiency induced by it .
the mechanism behind this remains unclear ; however , it is thought to be due to either alteration in small bowel motility , resulting in bacterial overgrowth and subsequent b12 deficiency , or by directly decreasing vitamin b12 absorption .
the deleterious effects of diabetes mellitus on the retinal , cardiovascular , and peripheral nervous systems are widely acknowledged ; however , very little concern has been shown toward the cognitive impairment seen in diabetics .
the cognitive decrements may involve memory function , executive function , and information - processing speed and therefore should raise an alarm and attract research toward itself .
cognition implies the thinking processes of the brain , using both the sensory input to the brain and the information already stored in the memory .
it is a complex phenomenon which relies on neurotransmitter processes such as serotonin , dopamine , and gamma - aminobutyric acid to coordinate the signals that are sent to the different areas of the brain such as the hippocampus and prefrontal cortex , which serve the episodic and working memory .
several tools and tests have been devised and standardized by physiologists and cognitive scientists to assess cognitive functions , which include bender - gestalt test , wechsler memory test , halstead - reitan categories test , trail making tests , and the mini - mental state examination .
however , electrophysiological tests have proven to be a reliable tool to document cognitive impairment in diabetes , even at an early stage of the disease .
cognitive functions of the brain are evaluated by using event - related potentials ( erps ) which are those potentials of the electroencephalogram ( eeg ) that are evoked by the perception of or the preparation for events , and they include an early sensory - evoked potential and a late cognitive response ( p300 component ) . in other words , it is evoked by unexpected stimuli and indicates the amount of processing required by a given stimulus .
vitamin b12 deficiency induced by metformin might be responsible for the cognitive impairment in these patients .
therefore , the present study aims at identifying whether metformin therapy induces vitamin b12 deficiency in type 2 diabetics and whether this b12 deficiency correlates with the degree of cognitive impairment in them by employing erps as a tool to study cognitive functions .
the study was carried out in the electrophysiological laboratory , department of physiology , ucms and gtb hospital , delhi .
the patients were recruited from the diabetic clinic , department of endocrinology and metabolism , ucms and gtb hospital , delhi .
the control group subjects were randomly chosen from the hospital staff . both , the people with diabetes and the control group subjects were age - matched .
a written informed consent was obtained from all the participants , for erps ' recordings and sample collection , prior to enrollment in the study .
study group : thirty type 2 diabetes mellitus patients taking a minimum dose of 1 g / day of metformin for at least 6 monthscontrol group : thirty normal healthy subjects of the same age group .
study group : thirty type 2 diabetes mellitus patients taking a minimum dose of 1 g / day of metformin for at least 6 months control group : thirty normal healthy subjects of the same age group .
subjects with history of head injury , epilepsy , migraine , drug abuse , malabsorption , type 1 diabetes , any other metabolic disorders , or neurological abnormality were excluded from the study .
subjects on vitamin b12 supplementation , subjects taking metformin for diseases other than diabetes , and subjects taking oral hypoglycemic other than metformin or in combination with metformin were also excluded from the study .
relevant history and examination to rule out exclusion criteria and to look for the presence of abnormality or disease if any was done .
height and weight of all subjects were measured and body mass index ( bmi ) calculated .
the recording was done from the scalp of the subjects using octopus 4 m / c ncv / emg / ep system by biostar healthcare , india . the recording was done in a sound - proof room , using the silver chloride disk electrodes placed at standard scalp locations of the 1020 international system .
the electrodes were placed at vertex of head ( reference electrode ) , forehead ( grounding electrode ) , and ear lobes ( active electrodes ) after cleaning the scalp and skin site with alcohol followed by skinpure skin preparation gel and eeg paste elefix. the skin electrode contact impedance was kept at < 10 k. during the recording session , subject was instructed to fix his eyes on a particular spot on the wall in front to avoid electro - oculographic artifacts due to eye movement .
the auditory erps were recorded using an oddball paradigm wherein two stimuli ( target and nontarget ) were presented in a random order by headphones .
the target stimulus was a 2 khz beep sound with 20% occurrence and the nontarget was a 1 khz click with 80% occurrence .
the auditory stimuli had 10 ms rise / fall time , 100 ms duration , and intensity of 90 db .
the evoked potentials were filtered with a band pass of 0.150 hz and averaged for 100 responses .
erps were recorded from the scalp of the subjects while the subjects performed psychomotor task on the computer .
the subjects had to press a button on the response pad with the thumb of their dominant hand on the hearing of target stimulus ( beep ) delivered by the headphones .
the peak latencies of the erps were evaluated from stimulus onset ( stimulus artifact ) to the peak point of the particular wave , i.e. , the point of greatest amplitude .
peak latencies of n100 , p200 , n200 , and p300 and amplitude of n200p300 wave were recorded and evaluated .
serum was then used for vitamin b12 assay which was based on the principle of elisa .
vitamin b12 levels were correlated with the dose and duration of metformin use using the spearman 's rho correlation coefficient .
the study was carried out in the electrophysiological laboratory , department of physiology , ucms and gtb hospital , delhi .
the patients were recruited from the diabetic clinic , department of endocrinology and metabolism , ucms and gtb hospital , delhi .
the control group subjects were randomly chosen from the hospital staff . both , the people with diabetes and the control group subjects were age - matched .
a written informed consent was obtained from all the participants , for erps ' recordings and sample collection , prior to enrollment in the study .
study group : thirty type 2 diabetes mellitus patients taking a minimum dose of 1 g / day of metformin for at least 6 monthscontrol group : thirty normal healthy subjects of the same age group .
study group : thirty type 2 diabetes mellitus patients taking a minimum dose of 1 g / day of metformin for at least 6 months control group : thirty normal healthy subjects of the same age group .
subjects with history of head injury , epilepsy , migraine , drug abuse , malabsorption , type 1 diabetes , any other metabolic disorders , or neurological abnormality were excluded from the study .
subjects on vitamin b12 supplementation , subjects taking metformin for diseases other than diabetes , and subjects taking oral hypoglycemic other than metformin or in combination with metformin were also excluded from the study .
relevant history and examination to rule out exclusion criteria and to look for the presence of abnormality or disease if any was done . height and weight of all subjects were measured and body mass index ( bmi ) calculated .
the recording was done from the scalp of the subjects using octopus 4 m / c ncv / emg / ep system by biostar healthcare , india . the recording was done in a sound - proof room , using the silver chloride disk electrodes placed at standard scalp locations of the 1020 international system .
the electrodes were placed at vertex of head ( reference electrode ) , forehead ( grounding electrode ) , and ear lobes ( active electrodes ) after cleaning the scalp and skin site with alcohol followed by skinpure skin preparation gel and eeg paste elefix. the skin electrode contact impedance was kept at < 10 k. during the recording session , subject was instructed to fix his eyes on a particular spot on the wall in front to avoid electro - oculographic artifacts due to eye movement .
the auditory erps were recorded using an oddball paradigm wherein two stimuli ( target and nontarget ) were presented in a random order by headphones . the target stimulus was a 2 khz beep sound with 20% occurrence and the nontarget was a 1 khz click with 80% occurrence .
the auditory stimuli had 10 ms rise / fall time , 100 ms duration , and intensity of 90 db .
the evoked potentials were filtered with a band pass of 0.150 hz and averaged for 100 responses .
erps were recorded from the scalp of the subjects while the subjects performed psychomotor task on the computer .
the subjects had to press a button on the response pad with the thumb of their dominant hand on the hearing of target stimulus ( beep ) delivered by the headphones .
the peak latencies of the erps were evaluated from stimulus onset ( stimulus artifact ) to the peak point of the particular wave , i.e. , the point of greatest amplitude .
peak latencies of n100 , p200 , n200 , and p300 and amplitude of n200p300 wave were recorded and evaluated .
serum was then used for vitamin b12 assay which was based on the principle of elisa .
vitamin b12 levels were correlated with the dose and duration of metformin use using the spearman 's rho correlation coefficient .
the cases and controls in the present study were selected from the same age group , but their mean age differed significantly , the mean age of the study group was 51.53 9.9 years and that of the control group 45.35 9.5 years .
the age- and gender - adjusted values obtained for all parameters are reported in the result , which have not been found to be significantly different from that obtained earlier .
the study group had 13 males and 18 females and the control group included 11 males and 19 females .
there was no significant difference in other baseline characteristics such as height , weight , and bmi among the study group and the control group .
the mean glycosylated hemoglobin ( hba1c ) in the diabetics was 7.14 1.3% , and the mean duration of diabetes was 4.15 2.5 years .
all the subjects in the present study were only on metformin therapy with no other medication .
the erps showed [ table 1 ] delayed latencies of waves p200 and p300 among the study group in comparison to the control group ( p = 0.034 and 0.001 , respectively ) .
the latencies of waves n100 and n200 and the amplitude of wave p300 , i.e. , n200p300 , did not show significant difference between the two groups .
event - related potentials compared in controls and study group the serum vitamin b12 levels were significantly deficient ( p = 0.00 ) in the study group , i.e. , in people with diabetes taking metformin ( 143 42.8 pg / ml ) as compared to the control group ( 274.5 64 pg / ml ) . the study group was divided into two groups according to the duration of metformin intake [ table 2 ] .
one group included people with diabetes taking metformin for < 5 years and the other included those taking metformin for 5 years .
serum vitamin b12 levels were significantly lower ( p = 0.00 ) in those taking metformin for 5 years as compared to those taking metformin for < 5 years .
however , on comparing the erps among these two groups , no significant difference was found in either the latencies or the amplitudes .
serum vitamin b12 levels in the study group depending on the duration of metformin exposure the study group was also divided into two groups according to the dose of metformin [ table 3 ] .
one group included people with diabetes taking < 1500 mg of metformin per day and those taking metformin 1500 mg / day .
serum vitamin b12 levels were significantly lower ( p = 0.00 ) in those taking 1500 mg metformin per day as compared to those taking < 1500 mg .
however , on comparing the erps among these two groups , no significant difference was found in either the latencies or the amplitudes .
serum vitamin b12 levels in the study group depending on the dose of metformin exposure vitamin b12 levels were found to have a significant negative correlation with the dose of metformin ( r = 0.7 ) and also a significant negative correlation with the duration of metformin intake ( r = 0.5 ) .
however , no significant correlation was found between the vitamin b12 levels and the erps .
the present study showed significantly delayed latencies of waves p200 and p300 in the people with diabetes taking metformin when compared to normal age - matched controls .
the n100 and p200 components of the erps reflect the activity occurring in neural areas activated by sensory stimuli and are independent of the subject 's attention .
it is generated from various sites of the brain including the cortical and subcortical areas , particularly the auditory cortex , hippocampus , amygdala , brainstem , and thalamic structures .
the p300 wave is believed to reflect cognitive processes underlying attention allocation and memory updating , and its amplitude indicates the amount of difficulty encountered in differentiating target from nontarget stimuli in the oddball paradigm of the erp .
the present study therefore observed cognitive impairment in the diabetics taking metformin . through the present study
, we also observed that serum vitamin b12 levels were deficient in diabetics taking metformin while they were not deficient in the control group .
in addition , this vitamin b12 deficiency was worse as the duration and dose of metformin exposure progressed .
various mechanisms have been proposed that may underlie this b12 deficiency induced by metformin , including :
alterations in small bowel motility which stimulates bacterial overgrowth and subsequent vitamin b12 deficiencycompetitive inhibition or inactivation of vitamin b12 absorptionalterations in intrinsic factor ( if ) levelsinteraction with the cubilin endocytic receptorinhibition of the calcium - dependent absorption of vitamin b12-if complex at the terminal ileum .
alterations in small bowel motility which stimulates bacterial overgrowth and subsequent vitamin b12 deficiency competitive inhibition or inactivation of vitamin b12 absorption alterations in intrinsic factor ( if ) levels interaction with the cubilin endocytic receptor inhibition of the calcium - dependent absorption of vitamin b12-if complex at the terminal ileum .
the present study demonstrated that the vitamin b12 deficiency worsened with the increase in dose and duration of metformin .
the presence of vitamin b12 deficiency was more in the metformin exposed group as compared to the nonmetformin exposed group and a significant inverse relationship existed between the b12 levels and the dose and duration of metformin .
another study demonstrated that patients with type 2 diabetes who were exposed to metformin for > 6 months had lower vitamin b12 levels and that vitamin b12 levels had a significant correlation with the dose of metformin .
type 2 diabetes has been associated with decreases in psychomotor speed , executive function , verbal memory , processing speed , complex motor functioning , and working memory . however , since the present study observed that the erps did not have any correlation with the vitamin b12 levels , vitamin b12 deficiency does not underlie the cognitive impairment seen in diabetics .
various studies have proposed that several mechanisms pertaining to diabetes are responsible for this cognitive impairment .
. mentioned that atherosclerosis , microvascular disease as a result of insidious ischemia , advanced protein glycation and oxidative stress as a result of glucose toxicity , and insufficient insulin action are major factors responsible for dementia in type 2 diabetics .
however , for cognitive dysfunction , either blood glucose disorders such as hyperglycemia or insulin disorders such as insulin resistance or microvascular damage may be held responsible . cognitive impairment due to hyperglycemia
can be attributed to neuronal changes as a result of advanced glycosylated end - product production and oxidative stress .
there is a large number of insulin receptors in the hippocampus and cerebral cortex , which play a central role in memory .
insulin induces the release of -amyloid peptide ( a ) in cells to the cell exterior and promotes the expression of insulin - degrading enzyme ( ide ) . in case of insulin resistance
, hyperinsulinemia causes downregulation of insulin receptors and also less insulin comes into the brain .
moreover , as insulin is degraded by ide , in the high insulin state , ide gets consumed resulting in an increase in a causing cognitive impairment .
another mechanism that may underlie cognitive disruption in type 2 diabetics is diabetic microvascular disease .
it has been proposed that damage to cerebral small vessels as a result of ischemia or damage to nerve sheaths is probably responsible .
abnormal polyol pathway and myoinositol metabolism could alter glucose metabolism in the frontal lobe , resulting in cognitive impairment . ideally ,
if the diabetics on metformin were compared with diabetics not taking metformin rather than normal subjects , it would have answered the research question better . however , since in our clinical setup , every person diagnosed with diabetes is started with metformin as the first - line treatment and even those taking combination therapy have metformin included in their treatment , so , taking this group was not possible for us .
ideally , if the diabetics on metformin were compared with diabetics not taking metformin rather than normal subjects , it would have answered the research question better . however , since in our clinical setup , every person diagnosed with diabetes is started with metformin as the first - line treatment and even those taking combination therapy have metformin included in their treatment , so , taking this group was not possible for us .
it is known that there is vitamin b12 deficiency in diabetes ; however , this can not be demonstrated by the findings of this particular studytreatment with metformin also seems to contribute to b12 deficiency as there is a dose- and duration - related correlationpeople with type 2 diabetes have impaired cognitive functions , but vitamin b12 deficiency does not seem to be responsible for it as no significant correlation was found between the vitamin b12 levels and the erps .
it is known that there is vitamin b12 deficiency in diabetes ; however , this can not be demonstrated by the findings of this particular study treatment with metformin also seems to contribute to b12 deficiency as there is a dose- and duration - related correlation people with type 2 diabetes have impaired cognitive functions , but vitamin b12 deficiency does not seem to be responsible for it as no significant correlation was found between the vitamin b12 levels and the erps . hence , treatment of diabetes adequate to check the progression of the disease process must be paid importance .
this can keep a check on the cognitive dysfunction and thus provide a better quality of life to people suffering from type 2 diabetes mellitus .
Output:
| introduction : diabetes mellitus has its deleterious effects on various aspects of cognition such as memory function , executive function , and information - processing speed .
the present study aims to assess cognition in diabetes patients and also tries to find its association with vitamin b12 deficiency induced by metformin.materials and methods : thirty diabetics taking metformin and thirty nondiabetic controls were enrolled .
event - related potentials ( erps ) and serum vitamin b12 levels were evaluated in them.results:vitamin b12 levels were found to be deficient , and latencies of waves p200 and p300 were prolonged in the diabetics as compared to the controls .
the dose and duration of metformin had no association with the erps.conclusions:although the vitamin b12 levels were deficient in diabetics on metformin , this is not the reason behind the cognitive impairment found in them . |
PubmedSumm118684 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: thyroid nodules are an extremely common occurrence and their prevalence in the general population is estimated to range between 50% and 67% , according to autoptic and ultrasonographic data . until recently , though , only a few remedies have been available for such a common disease . according to current guidelines , benign thyroid nodules should be followed up clinically . in order to avoid nodule enlargement , levothyroxine therapy , whose efficacy is still limited , and/or iodine should be taken into account in young patients with small nodules living in iodine - deficient areas . however , if nodular growth causes the onset of symptoms or cosmetic concerns the only available remedy so far has been surgery . not only is curative surgery invasive but it also has several drawbacks
radiofrequency ablation ( rfa ) is a relatively new technique that seems a safe and effective method for the debulking of large benign thyroid nodules and a promising treatment modality for autonomously functioning nodules [ 711 ] .
nevertheless , guidelines are cautious and rfa is not recommended yet in the routine management of benign thyroid nodules [ 3 , 4 ] .
here we aimed at ( i ) evaluating rfa efficacy , tolerability , and costs and ( ii ) comparing rfa outcomes to those of hemithyroidectomy , including short - stay thyroid surgery , for the treatment of benign thyroid nodules .
to assess rfa efficacy , complications , and costs we followed 37 patients who underwent rfa of their thyroid nodules between march 2012 and may 2013 .
overall , 38 rfa have been performed in 37 patients , as in one case the treatment was repeated . before the procedure , nodules were evaluated by fine needle aspiration biopsy ( fnab ) twice and classified according to the british and italian reporting systems for thyroid cytopathology .
rfa was performed on benign solitary nodules ( diagnostic category thy2/tir2 ) that measured > 2 cm and caused clinical problems ( neck pain , voice change , foreign body sensation , discomfort and cough , and cosmetic concerns ) or problems related to thyrotoxicosis , according to current recommendations . since caution should be exercised in patients with contralateral vocal cord palsy , patients presenting with voice changes underwent an otolaryngological visit and laryngoscopy to exclude such injury . to compare rfa outcomes with surgery
, we selected 74 patients among 525 patients who underwent thyroid surgery from may 2005 to may 2013 . these were all patients with benign single thyroid non - autoimmune nodules , who had undergone hemithyroidectomy , performed either in a standard inpatient surgical regimen ( > 24 hours , n = 64 , hemitx ) or in a short - stay regimen ( < 24 hours , n = 10 , short - stay ) .
patients who had already undergone contralateral thyroid lobectomy or who had had cytological preoperative diagnosis of malignancy ( diagnostic category thy5/tir5 ) or suspected malignancy ( thy4/tir4 ) as well as patients with nodules of undetermined significance ( thy3/tir3 ) and/or with increased calcitonin levels were excluded from the study .
this work was approved by the ethical committee of the azienda ospedaliero universitaria di trieste and informed consent was obtained from each patient , after full explanation of the purpose and nature of all procedures used , before inclusion in the study .
this study aimed at evaluating rfa outcomes and at comparing them to those of surgery .
firstly , to assess rfa efficacy and tolerability , patients underwent a medical visit , ultrasonography ( us ) , and thyroid - stimulating hormone ( tsh ) measurement at baseline , 1 , 3 , 6 , and 12 months after the procedure . during these visits , medication , nodule - related symptoms ( yes / no ) , cosmetic score ( 1 = no palpable mass ; 2 = palpable mass ; 3 = mass visible on swallowing ; 4 = easily visible mass ) , cosmetic results ( poor , acceptable , good , and excellent ) , pain , and/or other complications ( hematomas , skin burns , fever , and voice change ) were recorded . to measure nodule volume ( v ) and volume reduction ( vreduction )
the following formulas were used : v = abc/6 ( where v is the volume , a is the maximum diameter , and b and c are the other two perpendicular diameters ) and ( vreduction = ( initial finalv / initialv)100 ) .
vascularity was evaluated according to a 4-point scale where 0 is defined as no visible flow , 1 as peripheral flow only , 2 as peripheral flow with a small amount of central flow , 3 as peripheral flow plus extensive intranodular flow , and 4 as central flow only .
then , to compare the efficacy and tolerability of rfa to surgery , we took patient history , any current complaints ( neck symptoms yes / no ) , cosmetic results ( graded as poor , acceptable , good , and excellent ) , drug history , and tsh at baseline and one year after surgery . pain and complications of surgery
the endpoints for efficacy were ( i ) cure of nodule - related symptoms , ( ii ) patient satisfaction with cosmetic results , and ( iii ) antithyroid drugs ( atd ) withdrawal .
tolerability was expressed as ( i ) cases of postoperative pain , ( ii ) cases of iatrogenic hypothyroidism , and ( iii ) number of complications .
rfa was performed in an outpatient regimen by a well - trained radiologist experienced in us , fnab , and rfa procedures . before ablation
rfa did not require general anesthesia , and our patients underwent only local anesthesia at the puncture site with 2% lidocaine hydrochloride .
we used a radiofrequency generator ( viva rf generator ; amica rf generator ) and 18-gauge internally cooled electrodes with a 0.71.01.5 cm active - tip ( star rf probes starmed ; amica probes , hs amica ) .
the electrode was inserted into the thyroid nodule with a transisthmic approach under us - guidance by using a 716 mhz linear probe on a real - time us system ( aplio xg , toshiba medical systems corp . ) , as shown in figure 1(a ) . to perform rfa
ablation was begun with 30 w , starting from the deepest areas of the nodule .
if a hyperechoic zone had not formed at the electrode tip within 510 seconds , radiofrequency power was progressively increased in 10 w steps up to 60 w. the power would have been reduced or turned off in cases where patients could not tolerate pain during ablation , but no such case was encountered in our cohort . moreover ,
during the procedure there was an anaesthetist to assist the radiologist in case of pain , vasovagal reactions , or interference with pacemaker devices , but no such case was encountered in our cohort .
ablation was terminated when transient hyperechoic zones could be identified around the whole nodule , as shown in figures 1(b)-1(c ) . at the end of the procedure a mild compression was applied to the site of the needle insertion for 510 minutes and patients remained under observation for a few hours in case they had complications .
pain was recorded 4 hours after the procedure and scored according to the visual analogue scale ( vas ) ranging from 0 to 10 with the words no pain = 0 on the left hand side and worst possible pain = 10 on the right hand side .
patients were allocated to short - stay hemithyroidectomy according to their age , residence , nodule size , and comorbidities .
all operations were carried out by the same team , which included two surgeons ( lead and assistant surgeon ) .
hemithyroidectomy was performed by a single access of 25 cm in the middle area of the neck , approximately 2 cm above the sternal notch .
patients , under general anaesthesia , were placed in the supine position with the neck extended .
the vessels of the upper thyroid peduncle were selectively ligated or closed by conventional vascular clips .
once the thyroid lobe and isthmus had been removed , the area was examined for bleeding .
if there was no bleeding , the incision was closed with sutures . in some cases ,
a surgical drain was placed to remove fluids from the area in the following days .
anaesthesia was discontinued and medication was given to wake the patient . in those patients who underwent standard inpatient hemithyroidectomy , postoperative
pain and serum calcium were measured 4 and 24 hours after surgery , together with parathormone ( pth ) .
those who underwent short - stay surgery were admitted the day of operation and observed overnight . here
postoperative pain and serum calcium were evaluated 4 and 20 hours after surgery , together with pth .
discharge criteria included no wound or airway problems , stable vital signs , tolerance of normal diet and activity , and an upsloping serum calcium curve .
cost analysis included the procedure ( rfa or surgery ) and the respective pre- and postprocedural exams .
preprocedural exams included laboratory tests ( full blood count , coagulation tests , tsh , thyroid hormones , calcitonin , and thyroid autoantibodies ) , us and anaesthesiological visit , and an otolaryngological visit in selected cases ( among our patients , 2 out of 37 underwent such a visit ) .
the cost of the procedure included the equipment , consisting of scanner , needle , and drugs , as well as the personnel , consisting of one radiologist , one anaesthetist , and two nurses .
in particular , the cost of any us scanner can be divided into depreciation and maintenance .
apart from maintenance , which is negligible , the purchase cost of our us scanner was 97,489 , which equals an average annual cost of 12,186 over 8 years of depreciation .
therefore , assuming 250 working days per year , the daily cost of the scanner is 48.74 per day and since it is used for 12 hours per day and the length of one rfa is 45 minutes , the final cost of a scanner is 3.04 per exam .
drugs were lidocaine ( 0.013/ml ) , midazolam ( 0.099/ml ) , fentanyl ( 0.140/ml ) , droperidol ( 3.168/ml ) , and saline ( 0.834/ml ) .
the cost of the radiologist and the anaesthetist was calculated according to their working time , which is 1,330 hours / year , and their gross annual salary , which is 101,040 in both cases ( excluding social security and termination bonus ) , corresponding to a salary of 76 per hour .
likewise , the gross annual salary of a nurse is 39,174 ( excluding social security and termination bonus ) , corresponding to a salary of 29 per hour .
preprocedural exams included laboratory tests ( including full blood count , urea and electrolytes , glucose , urine analysis , liver function test , coagulation blood tests , blood type , hiv and markers of hepatitis , and tsh ) , ecg , chest x - ray , and otolaryngological and anaesthesiological visits .
the costs of the procedure included hospital stay ( 375/night ) , the operating theatre ( 24/min ) , the variable costs for technical textiles ( 31.50 ) , the sterilization of surgical instruments ( 95.30 ) , scalpels ( 0.20 ) , suction cannulas ( 23.80 ) , sutures ( 23.99 ) , bipolar forceps ( 19.05 ) , tampons ( 0.69 ) , and redon sets ( 3.04 ) . the drugs that were used were remifentanil ( 304.20/5 mg ) and desflurane ( 0.35/ml ) .
personnel consisted of two surgeons , one theatre nurse , two nurses , and one anaesthetist , whose costs were calculated as above .
test was used to compare sex , nodules ' characteristics , symptoms , hyperthyroidism , and autoimmunity between the two groups .
there were no differences between the nodules treated by rfa and those treated by surgery in terms of cystic component , macrocalcifications , and vascularization . in this study ,
in particular , the nodules ' volume was 12.45 2.52 ml at baseline , 6.44 ml 1.77 ml after 1 month from the procedure ( p < 0.05 versus baseline ) , 5.45 1.50 ml after 3 months ( p < 0.05 versus baseline ) , 4.56 1.40 ml after 6 months ( p < 0.05 versus baseline ) , and 3.91 0.98 ml after 12 months ( p < 0.05 versus baseline ) . in other words , the volume decreased by 47% , 61% , 66% , and 70% at 1 , 3 , 6 , and 12 months after rfa .
the greatest volume reduction was observed within the first month and this was more pronounced in the lesions with more than 50% of liquid content .
therapeutic success was achieved with a single session in 36 out of 37 patients , as only one patient required two sessions to achieve a final volume reduction of 77% .
this patient had a solid nodule , with peripheral plus intranodular flow , measuring 42 36 31 mm . in this case
, rfa was repeated 6 months after the first session because the nodule had decreased less than 50% of its initial volume .
apart from volume reduction , rfa lessened nodular echogenicity and made intranodular vascularity disappear , as shown in figure 3 . on the other hand , hemithyroidectomy
was successfully completed in all the cases . in particular , among the 74 patients who underwent surgery , 64 subjects underwent a hemithyroidectomy performed in a standard inpatient surgical regimen and 10 subjects underwent a hemithyroidectomy performed in a short - stay surgical regimen .
the groups differed only in terms of number of patients with neck symptoms , which was higher in the surgical group .
focusing on the efficacy of these techniques , rfa was able to cure nodule - related symptoms in the majority of patients ( 11 patients out of 13 ) and was not inferior to surgery , as shown in table 2 .
in particular , while neck symptoms were resolved completely in 11 patients out of 13 treated by rfa , they ameliorated in the other 2 cases , as these patients were suffering from gastroesophageal reflux disease , which might have contributed to their local discomfort .
secondly , there were no differences between rfa and surgery in terms of cosmetic results , which were excellent for the vast majority of patients in both groups ( 35 out of 37 patients for rfa and 65 out of 74 for surgery ) .
in particular , rfa significantly reduced the cosmetic score , which went down from 3.4 to 2.4 per patient ( p < 0.05 ) ; in other words , nodules that were visible could no longer be seen after the procedure .
excellent by 35 patients ( 94% ) , while the remaining two had nodules measuring more than 35 ml initially which resulted in a final volume of 15 ml .
in these two cases , cosmetic results were scored as acceptable . on the other hand , 88% of the patients ( 65 ) who had undergone surgery judged the results as excellent , while they were
good for 9% of the patients ( 7 ) and acceptable only for 3% of the patients ( 2 ) , depending on their scar . in particular , in our cohort ,
the cosmetic benefit of thyroid nodule removal was felt to outweigh the presence of a scar in 65 patients out of 74 , while in the remaining 9 patients the scar compromised the final cosmetic result .
overall , the volume reduction achieved by rfa did not affect thyroid function , which remained unchanged throughout the entire follow - up period .
in particular , tsh was 1.30 0.25 u / ml at baseline , 1.48 0.25 u / ml at 1 month , 1.24 0.22 u / ml at 3 months , 0.95 0.15 u / ml at 6 months , and 1.37 0.28 u / ml at 12 months after the procedure .
having said that , in the subgroup of hyperthyroid patients ( n = 12 ) , rfa improved thyroid function as tsh increased from 0.28 0.08 microu / ml to 1.35 0.31 microu / ml ( p < 0.05 ) after just one month from the procedure and it was maintained throughout the study period . thanks to this effect , 4 patients out of 12 could stop or avoid taking any atd , as their thyroid function normalized completely , whereas the remaining 8 patients could reduce the number of tablets from 1 tablet every day to 1 tablet every two days . nevertheless , this effect was not enough for these 8 patients and rfa was significantly less effective compared to surgery for the treatment of autonomously functioning nodules , as shown in table 2 .
postoperative pain was rare as in only 2 cases out of 38 sessions pain was reported .
pain was mild , was treated by paracetamol , scored 2.5 0.8 points , and ceased within 2 weeks . apart from this , in our study , rfa complications were 1 case of transient voice change and 1 case of late - onset , painless thyroiditis with transient thyrotoxicosis .
the voice change was treated by prednisone and was resolved within 1 and a half months . the late - onset painless thyroiditis with thyrotoxicosis developed 3 months after the procedure and resolved spontaneously within 30 days . moreover , such thyroiditis did not cause hypothyroidism .
there were no vasovagal reactions or cases of haemorrhage , skin burn , or fever .
surgery was also well tolerated , but not as much as rfa ( see table 2 ) .
pain was always treated by paracetamol postoperatively so it was mild and scored on average 2.9 0.1 .
these included 4 cases of transient hypocalcemia ( serum calcium < 8.5 mg / dl with slightly reduced but normal pth ) , 6 cases of monolateral transient nerve palsy , and 2 cases of wound complications .
only 17 patents had to take levothyroxine after surgery for the first time . considering that 6 patients had been taking levothyroxine before surgery , the majority ( 51 ) of the remaining 68 patients , however , remained euthyroid .
focusing on costs , the length of one rfa session was 45 minutes and it was performed in an outpatient regimen and cost of 1,661.50 .
the mean operative time for hemithyroidectomies performed in a standard inpatient regimen was 80 minutes , the length of the hospital stay was 2.33 days , and their mean cost was 4,556.30 . in the group requiring short - stay surgery , mean operative time was 82.5 minutes , hospital stay was 1 day , and the cost was 4,139.40 , as reported in table 3 .
having said that , another aspect we considered was the contribution to patient management of final pathology , which only occurred in the surgical approach .
final pathology showed that 68 patients out of 74 ( 92% ) presented with benign thyroid nodules .
44 nodules were follicular adenomas , 12 were nodular thyroiditis , 6 were colloid lesions , 4 were degenerative cysts , 1 was a hurtle cell adenoma , and 1 was a nodule within riedel 's thyroiditis .
so , despite the fact that before surgery all fnab were benign , 6 nodules ( 8% ) were found to be harbouring malignant cells on final pathology and 5 cases were papillary microcarcinomas ( < 1 cm ) while 1 case was a papillary carcinoma ( > 1 cm ) .
our comparative data show that rfa significantly reduces thyroid nodule volume and relieves from nodule - related clinical problems , such as local symptoms and cosmetic concern , as effectively as surgery . in this study , 12 months after rfa , thyroid nodules had shrunk by 70% , and the best results were achieved in nodules with a mixed content and an initial volume < 35 ml .
this is in line with previous studies demonstrating that rfa can reduce nodule volume by 3358% after one month , by 5185% after six months [ 11 , 17 ] , and by 93% after four years from the procedure .
different percentages of volume reduction can be attributed to the number of sessions , which in our study were 1.03 per patient , whereas in other studies were 1.8 per patient . moreover , although the length of our follow - up is 12 months , it has already been demonstrated that the volume reduction achieved is maintained up to 4 years after rfa .
volume reduction did not affect thyroid function in euthyroid patients , which might have been due to the fact that there was a negligible number of autoimmune thyroiditis , but it was able to normalize tsh in some of the patients with hot nodules .
however , hyperthyroidism was completely resolved only in 33% of patients , indicating that in our study rfa was significantly less effective than surgery for the treatment of hyperfunctioning nodules .
this is consistent with what has already been reported by the groups of deandrea et al . , who showed that hyperfunction was fully controlled in 24% of patients at 6 months after rfa , and by faggiano et al . , who further showed that hyperfunction was fully controlled in 40% of patients with hot nodules at 12 months after rfa
having said that , spiezia and colleagues have demonstrated that 2 years after rfa thyroid function normalized in 100% of patients with pretoxic nodules and in 53% of patients with toxic nodules .
further studies are needed to clarify whether two rfa sessions could cure hyperfunctioning nodules as effectively as surgery , since incomplete recovery could be explained by the difficulty in ablating the entire nodule and the regrowth of the untreated peripheral portion .
so , our comparative study ( rfa versus surgery ) shows that current recommendations on rfa are effective and applicable in treating thyroid nodules causing symptoms and cosmetic concerns , while the best approach to treat autonomously functioning nodules is surgery and not rfa . in general ,
apart from two cases of mild pain and one case of a transient voice change there were no other complications , which could be ascribed to the technique that was used . to avoid thermal nerve injury the moving - shot technique and undertreating the area adjacent to the nerve , also called the danger triangle , as shown in figure 2 ,
one patient developed a late - onset , painless thyroiditis with transient thyrotoxicosis 3 months after rfa , which we report for the first time as one of the potential rfa complications .
the presence of a thyrotoxicosis was suggested by thyroid hormones ' increase and tsh decrease .
the presence of a thyroiditis was suggested by the positivity of anti - tpo antibodies , which were absent at baseline , and the suppressed thyroid radioiodine uptake .
such thyroiditis with thyrotoxicosis was transient , as it resolved spontaneously within a few weeks and it did not cause hypothyroidism .
this case of painless thyroiditis with thyrotoxicosis brings into mind postaspiration thyrotoxicosis , which is believed to be an inflammatory process that takes place after needle aspiration of the thyroid and triggers the release of thyroid hormones .
given the proximity to rfa , it is conceivable that such thyroiditis with thyrotoxicosis might have been caused by this procedure through a mechanism similar to that of postaspiration thyrotoxicosis .
as compared to rfa , surgery caused hypothyroidism in 25% of patients and had a higher complication rate , although they were all mostly mild and transient , and nobody developed life - threatening problems such as haemorrhage , laryngeal edema , or tetany , in keeping with previous data [ 22 , 23 ] .
overall , there were 6 cases of transient nerve palsy , 4 cases of transient hypocalcemia , and 2 cases of wound complications .
hypocalcemia after hemithyroidectomy might be explained by the unintended excision of one or more parathyroids together with metabolic factors such as hungry bones associated with thyrotoxicosis .
although the majority of patients were very pleased with surgical results , consistent with the literature , our data on the baseline characteristics might suggest that patients are not always comfortable with undergoing surgery .
in fact , in our view , only the onset of neck symptoms or strong cosmetic concerns , which outweigh the lingering apprehension over the risk of surgical complications , would have encouraged our patients to undergo surgery .
the last decades have witnessed a quiet revolution in relation to the management of benign thyroid diseases .
advances in surgical techniques are making surgery not only safer but also minimally invasive if not totally scarless .
in addition , thanks to the improvements in the management of bleeding , pain , and hypoparathyroidism , hospital stays have decreased to below 23 hours .
today , the advantages of outpatient surgery include reduced costs , reduced inpatient waiting lists , increased availability of inpatient beds , and the psychological benefit of avoiding prolonged hospitalization .
having said that , there are clearly social and clinical circumstances in which outpatient thyroidectomy is not possible .
moreover , even if it were feasible , outpatient thyroid surgery remains controversial , given that the likelihood of delayed haemorrhage and one case of death have been reported .
notwithstanding several potential benefits , those who argue against outpatient surgery maintain that hospital cost savings should not be at the expense of patient safety . in regard to this point , it is abundantly clear that rfa is safer .
there is no risk of hypocalcemia , nerve injury can be easily avoided ( voice changes are reported in 1% of cases ) , and there have been no reports so far of life - threatening events [ 6 , 13 , 18 , 19 ] . in addition , rfa does not require general anaesthesia .
so , rfa could prove useful for treating weak or elderly patients or those with challenging hemostasis , comorbidities , and other clinical or social issues not conducive to surgery .
in addition to its efficacy and safety , here we show that rfa compares extremely favorably to surgery in terms of costs , as it costs roughly 2.6 times less than surgery , without including the fact that sick - leave is significantly shorter and social costs are significantly lower .
however dramatically renewed surgery might be , the greatest shift in the future routine management of benign thyroid nodules will probably be determined by the availability of nonsurgical , minimally invasive techniques .
these techniques together with recent advances in molecular biology are likely to minimize unnecessary surgery .
the group of arora and colleagues analysed 826 thyroid surgical specimens and came upon 8 carcinomas ( 2% ) within benign nodules . in another work , park and
colleagues discovered occult papillary carcinomas in 9.2% of adenomatous goiters and 4.3% of follicular adenomas .
this is in line with the recent study carried out by wang and collaborators who showed that on average 6% of benign nodules are found postoperatively malignant by cytopathology diagnosis .
these findings clearly demonstrate that some benign nodules may harbour microscopic foci of malignancy that can be missed at the fnab due to sampling error .
it is not clear when these foci developed , whether they are bound to grow , and whether molecular biology will enable us to overcome this issue by differentiating these nodules from those that are totally benign .
here we found 6 carcinomas in 74 nodules ( 8% ) that had been classified as benign nodules by fnab .
it has to be noted , though , that before surgery fnab had not always been performed with ultrasonography .
it is exactly for reducing the likelihood of false cytologically benign fnab that before rfa it is recommended to perform two ultrasonographic - guided fnab , in both functioning and nonfunctioning nodules , as we did in this study before rfa .
it is absolutely clear that the strength of surgery is that it allows for the final pathology and therefore the diagnosis and cure of cancer .
however , it is argued that low - risk thyroid cancer , such as microcarcinomas , is being overtreated nowadays as small papillary cancers may never progress to cause symptoms or death . to back this view a recent observation trial on papillary thyroid microcarcinoma
has in fact shown that tumor enlargement and new onset of node metastases were detected in only 6.5% and 1.4% of patients after 5 years of observation . moreover , none of the patients having a microcarcinoma who underwent surgery after 5 years of follow - up showed postoperative carcinoma recurrence and none of the patients who underwent observation showed distant metastasis or died of thyroid carcinoma .
these data would therefore suggest that papillary microcarcinoma has an indolent nature and immediate surgery is not mandatory .
moreover , a recent study by the group of valcavi has demonstrated that percutaneous laser ablation is technically feasible for complete destruction of papillary microcarcinomas .
still , one of the biggest issues about the use of rfa on thyroid nodules is that we still do not know its impact on malignancy in the long term .
although rfa has been successfully used for locoregional control of cancer or improvement of cancer - related clinical symptoms in patients with recurrent thyroid cancer and either a high surgical risk or unwillingness to undergo repeated surgery , there are no long - term follow - up data on radiofrequency ablated benign thyroid nodules harbouring malignant cells and therefore on how to monitor these cases .
it is exactly for this reason that it would be sensible to continue the monitoring of the ablated nodules at least yearly for 5 years .
having said that , if rfa could cure occult carcinomas , then it would definitely kill three birds ( efficacy , safety , and costs ) with one stone .
in conclusion , our comparative study suggests that rfa represents an effective alternative to surgery , which is very expensive and occasionally unnecessary , for the treatment of benign thyroid nodules causing local symptoms or cosmetic concerns .
nevertheless , this study does not dismiss surgery , which , on the contrary , is more effective than one rfa session for treating nodules with an initial volume greater than 35 ml as well as for autonomously functioning nodules . since rfa does not allow for final pathology
, patients should undergo two ultrasonographic - guided fnab prior to the procedure and should be followed at least yearly for five years .
Output:
| objective .
benign thyroid nodules are a common occurrence whose only remedy , in case of symptoms , has always been surgery until the advent of new techniques , such as radiofrequency ablation ( rfa ) . this study aimed at evaluating rfa efficacy , tolerability , and costs and comparing them to hemithyroidectomy for the treatment of benign thyroid nodules .
design and methods .
37 patients who underwent rfa were retrospectively compared to 74 patients surgically treated , either in a standard inpatient or in a short - stay surgical regimen .
efficacy , tolerability , and costs were compared .
the contribution of final pathology was also taken into account .
results .
rfa reduced nodular volume by 70% after 12 months and it was an effective method for treating nodule - related clinical problems , but it was not as effective as surgery for the treatment of hot nodules .
rfa and surgery were both safe , although rfa had less complications and pain was rare .
rfa costed 1,661.50 , surgery costed 4,556.30 , and short - stay surgery costed 4,139.40 per patient .
rfa , however , did not allow for any pathologic analysis of the nodules , which , in 6 patients who had undergone surgery ( 8% ) , revealed that the nodules harboured malignant cells . conclusions .
rfa might transform our approach to benign thyroid nodules . |
PubmedSumm118685 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: the b - type natriuretic peptide ( bnp ) and the amino - terminal fragment of the pro - b - type natriuretic peptide , known as nt - probnp , are currently seen as gold standard biomarkers for the diagnosis and prognostic stratification of heart failure , according to international guidelines [ 1 , 2 ] .
these biomarkers are not only able to discriminate the origin of dyspnea ( cardiac versus non - cardiac dyspnea , e.g. bronchial asthma ) in the setting of emergency medicine [ 1 , 2 ] , but they are also useful for better managing patients with stable chronic heart failure ( chf ) . indeed , in the last decade , there have been developments in the concept of bnp - guided therapy , in which the serial measurements of bnp over time are used to assess the effectiveness of drug treatment for heart failure , and to guide possible adjustments and modifications to dosage .
however , the current methods for the measurement of bnp are invasive , requiring a venous blood sample ( e.g. from the antecubital vein of the arm ) , with specific pre - analytical requirements in order to make the interpretation of the results feasible . in this context
, the relative discomfort resulting from venipuncture and the relatively long period of time needed to get the test results could be an obstacle to a strict careful monitoring of the patient with repeated tests for bnp from venous blood .
these constraints prevent the monitoring of the bnp levels at home or at the office of the general practitioner and require that patients are directed to centers for laboratory investigations . to overcome these limitations ,
some systems suitable for allowing rapid and non - invasive measurement of multiple biological parameters , including the bnp , have been developed .
ideally , such a so - called point - of - care ( poc ) should measure the bnp from capillary blood , similarly to blood sugar measurement from the fingertip in diabetic patients .
these pocs have many advantages , e.g. , greater convenience and speed of detection of the results than in the reference methods .
a system for detecting analytes at the bedside ( poc ) would enable easy and quick bnp monitoring even in a remote way , and would be useful for routine checks at the offices of the primary care physician or of the community cardiologist .
in addition , poc may also be used in hospitals for the rapid monitoring of bnp - guided treatment of heart failure during an outpatient visit in the department of cardiology and for a rapid triage of patients with acute dyspnea in the emergency department . however , although promising , the preparation and evaluation of a poc as a diagnostic routine tool requires that this kind of method is conveniently assessed to test adequately its reliability in comparison with the reference methods , i.e. those used in laboratories for blood analyses . until a short time ago , the two pocs available for the measurement of bnp were the alere triage and the abbott i - stat [ 5 , 6 ] , the latter using venous or arterial whole blood , while the former uses plasma treated with ethylenediaminetetraacetic acid ( edta ) as a chelating agent ( table 1 ) [ 6 - 9 ] .
in contrast , the alere heart check bnp test is the first poc designed as a type of immunological assay for the measurement of bnp from whole untreated capillary blood .
two preview studies demonstrated the safety and feasibility of this test at home for patients and healthcare providers .
however , no peer - reviewed studies have compared the alere heart check bnp test with the reference methods used in the medical laboratory , except for the data provided by the alere heart check bnp test compared with the beckman coulter access ii bnp assay . therefore , the aim of this study was to evaluate the clinical performance of this new poc to measure bnp by comparing it with our consolidated reference method ( abbott architect system ) , as an analytical prerequisite for a large deployment of this system in the hospital .
we enrolled 111 patients with stable chf who were followed at the two cardiac rehabilitation units that participated in our search ( e.da . and s.m.d.p . ) from february 2013 to january 2015 . for enrollment ,
only patients with chf in new york heart association ( nyha ) classes i - iii were considered , irrespective of the origin ( coronary artery disease , cardiomyopathy , valvular disease , etc . ) of their cardiac insufficiency .
patients with a clinical picture of instability ( i.e. , patients with acute decompensated heart failure ) were excluded .
both chf patients with reduced left ventricular ejection fraction ( lvef ) and those with preserved lvef were included in the study .
heart failure was defined as the inability of the heart to pump sufficiently to maintain blood flow to meet the body s needs . for clinical categorization s purposes
, we used the nyha classes , according to the usual significance attributed to each class , as reported in table 2 .
these patients were subjected to simultaneous capillary ( alere heart check system ) and plasma ( abbott architect system ) bnp measurement .
plasma was obtained from edta blood samples centrifuged at 3,500 g for 15 min at 4 c .
this method was a one - step immunoassay that uses biotinylated anti - bnp monoclonal antibody and streptavidin - coated magnetic solid - phase particles that were used to attract the immune binding of latex particles coupled with horseradish peroxidase and a monoclonal antibody fragment .
this generated an electrochemical detection signal proportional to the level of bnp in the patient sample .
the alere heart check was ready to use on a static or mobile device ; capillary blood obtained by pricking was deposited on a single - use test strip , and could be performed by patients themselves .
the abbott architect system was the lab - based system used in our hospitals for the routine measurement of plasma bnp ; this method was valid and considered as a reference method .
it was based on a two - step sandwich immunoassay using monoclonal antibodies specific for human bnp ; detection was done by chemiluminescence .
the limits of detection were 10 - 5,000 pg / ml . unlike the alere heart check , the abbott architect system required plasma to be obtained from edta whole blood by centrifugation at 3,500 g for 15 min at 4 c , within 4 h after collection .
repeatability was assessed by performing six repeated measures of the low and high bnp controls on the same day by the same operator using strips and controls from the same batch .
reproducibility was assessed by performing six measures of the low and high bnp controls per day , over three consecutive days using three different strip batches .
all statistical analyses were performed using the stata version 10 statistical software ( statacorp lp , college station , tx , usa ) .
values were expressed as median ( interquartile range ) , mean sd or number ( % ) as appropriate .
the difference between capillary and plasma bnp was assessed by mann - whitney test ( independent samples ) .
linear regression analysis was made for evaluating the relationship between the bnp values , respectively measured by means of the alere heart check system and abbott architect system , the latter being used as reference method .
thus , the regression coefficient ( slope ) and the correlation coefficient concerning the two methods of bnp measurement were calculated .
bland - altman plot was built for highlighting the difference between the two techniques for the calculated bnp value , by plotting this difference against the averages of the two techniques .
receiver operator characteristic curves were generated for evaluating the diagnostic accuracy of the two tests ( alere heart check and abbott architect ) .
we enrolled 111 patients with stable chf who were followed at the two cardiac rehabilitation units that participated in our search ( e.da . and s.m.d.p . ) from february 2013 to january 2015 . for enrollment ,
only patients with chf in new york heart association ( nyha ) classes i - iii were considered , irrespective of the origin ( coronary artery disease , cardiomyopathy , valvular disease , etc . ) of their cardiac insufficiency .
patients with a clinical picture of instability ( i.e. , patients with acute decompensated heart failure ) were excluded .
both chf patients with reduced left ventricular ejection fraction ( lvef ) and those with preserved lvef were included in the study .
heart failure was defined as the inability of the heart to pump sufficiently to maintain blood flow to meet the body s needs . for clinical categorization s purposes
, we used the nyha classes , according to the usual significance attributed to each class , as reported in table 2 .
these patients were subjected to simultaneous capillary ( alere heart check system ) and plasma ( abbott architect system ) bnp measurement .
plasma was obtained from edta blood samples centrifuged at 3,500 g for 15 min at 4 c .
this method was a one - step immunoassay that uses biotinylated anti - bnp monoclonal antibody and streptavidin - coated magnetic solid - phase particles that were used to attract the immune binding of latex particles coupled with horseradish peroxidase and a monoclonal antibody fragment .
this generated an electrochemical detection signal proportional to the level of bnp in the patient sample .
the alere heart check was ready to use on a static or mobile device ; capillary blood obtained by pricking was deposited on a single - use test strip , and could be performed by patients themselves .
the abbott architect system was the lab - based system used in our hospitals for the routine measurement of plasma bnp ; this method was valid and considered as a reference method .
it was based on a two - step sandwich immunoassay using monoclonal antibodies specific for human bnp ; detection was done by chemiluminescence .
the limits of detection were 10 - 5,000 pg / ml . unlike the alere heart check , the abbott architect system required plasma to be obtained from edta whole blood by centrifugation at 3,500 g for 15 min at 4 c , within 4 h after collection .
repeatability was assessed by performing six repeated measures of the low and high bnp controls on the same day by the same operator using strips and controls from the same batch .
reproducibility was assessed by performing six measures of the low and high bnp controls per day , over three consecutive days using three different strip batches .
all statistical analyses were performed using the stata version 10 statistical software ( statacorp lp , college station , tx , usa ) .
values were expressed as median ( interquartile range ) , mean sd or number ( % ) as appropriate .
the difference between capillary and plasma bnp was assessed by mann - whitney test ( independent samples ) .
linear regression analysis was made for evaluating the relationship between the bnp values , respectively measured by means of the alere heart check system and abbott architect system , the latter being used as reference method .
thus , the regression coefficient ( slope ) and the correlation coefficient concerning the two methods of bnp measurement were calculated .
bland - altman plot was built for highlighting the difference between the two techniques for the calculated bnp value , by plotting this difference against the averages of the two techniques .
receiver operator characteristic curves were generated for evaluating the diagnostic accuracy of the two tests ( alere heart check and abbott architect ) .
from february 2013 to january 2015 , we enrolled 111 patients with stable chf , mostly men ( 65% ) , whose characteristics are presented in table 3 .
fifty - four patients ( 48.6% ) had a reduced ejection fraction ( 50% ) mainly due to ischemic cardiac disease , and 49 ( 44% ) had symptomatic heart failure ( nyha functional classes ii - iii ) .
the patients underwent two types of blood sampling , one venipuncture and one fingertip capillary blood sample .
bmi : body mass index ; nyha : new york heart association ; lvef : left ventricular ejection fraction ; ckd : chronic kidney disease ; egfr : estimated glomerular filtration rate ; icd : implantable cardioverter defibrillator ; pm : pace - maker ; bnp : b - type natriuretic peptide ; ace - i : angiotensin converting enzyme inhibitor ; arb : angiotensin receptor blocker .
overall , the bnp values obtained ranged between 95 and 2,178 pg / ml using the alere heart check , and between 89 and 1,435 pg / ml using the architect system .
there was a strong positive correlation between the two measurements ( r = 0.947 , p < 0.0001 ) , although the values diverged more when bnp was higher than 1,500 pg / ml ( fig .
bland - altman analysis confirmed this difference ( bias of 46.9 pg / ml ) , some values above 1,500 pg / ml being outside the 95% limit of agreement ( fig .
2 ) . distribution of capillary bnp measured on the alere heart check system according to plasma bnp measured on the abbott architect system among the 111 patients with chf , examined in the study .
we compared both methods for their diagnostic accuracy in distinguishing the asymptomatic chf patients , i.e. belonging to nyha functional class i , from those with symptoms , i.e. belonging to nyha functional classes ii - iii .
the methods ( alere heart check vs. abbott architect ) showed similar diagnostic performances ( figs . 3 and 4 ) with values of area under the curve ( auc ) of 0.983 and 0.984 , respectively , and equivalent sensitivities , specificity , and positive and negative likelihood ratios . in this roc plot
, there is the representation of the very good diagnostic performance ( auc = 0.983 ) of the alere check system as a tool for predicting a clinical picture of chf belonging to nyha classes ii - iv . by adopting this method ,
the best diagnostic accuracy for identifying a condition of nyha class ii or higher has been attributed to the bnp threshold value of 412 pg / ml .
this means that this value , when derived from a measurement made by the alere check system on capillary blood , is associated to the presence of heart failure symptoms with a sensitivity of 95.9% and a specificity of 91.9% ( note on top of the graph ) .
chf : chronic heart failure ; nyha : new york heart association ; roc : receiver operating characteristic ; auc : area under the curve ; bnp : b - type natriuretic peptide ; pg : picogram . in this roc plot
, there is the representation of the very good diagnostic performance ( auc = 0.984 ) of the abbott architect system as a tool for predicting a clinical picture of chf belonging to nyha classes ii - iv .
the criterion value of 438 pg / ml has been identified as the bnp value that exhibits the best diagnostic accuracy for predicting the presence of symptoms of heart failure .
this means that this value , when the bnp measurement is done from plasma using the abbott architect system , is associated with heart failure symptoms with the best combination of sensitivity and specificity ( 91.8% and 96.8% , respectively ) .
chf : chronic heart failure ; nyha : new york heart association ; roc : receiver operating characteristic ; auc : area under the curve ; bnp : b - type natriuretic peptide ; pg : picogram .
we subsequently compared the results from capillary and plasma bnp measurements , according to the nyha functional classification of dyspnea ( figs .
5 - 7 ) . below there are the pertinent findings , that we have found for each nyha class by measuring the bnp levels in capillary whole blood ( alere heart check system ) and edta plasma from venous sample ( abbott architect system ) respectively , expressed as median plus interquartile range .
there was no statistical difference between capillary and plasma bnp according to the nyha class of patients ( nyha i : 245 pg / ml ( 168.5 - 348.25 ) vs. 251 pg / ml ( 194 - 381 ) ; nyha ii : 610.5 pg / ml ( 500 - 765 ) vs. 578.5 pg / ml ( 495 - 699 ) ; nyha iii : 1,223 pg / ml ( 923.75 - 1,309.75 ) vs. 897 pg / ml ( 802.5 - 1,087.5 ) ) .
comparison of capillary ( alere heart check system ) and plasma ( abbott architect system ) bnp levels in patients with chronic heart failure nyha class i ( n = 62 ) .
comparison of capillary ( alere heart check system ) and plasma ( abbott architect system ) bnp levels in chronic heart failure patients with nyha class ii ( no = 30 ) .
comparison of capillary ( alere heart check system ) and plasma ( abbott architect system ) bnp levels in chronic heart failure patients with nyha class iii ( no = 19 ) .
from february 2013 to january 2015 , we enrolled 111 patients with stable chf , mostly men ( 65% ) , whose characteristics are presented in table 3 .
fifty - four patients ( 48.6% ) had a reduced ejection fraction ( 50% ) mainly due to ischemic cardiac disease , and 49 ( 44% ) had symptomatic heart failure ( nyha functional classes ii - iii ) .
the patients underwent two types of blood sampling , one venipuncture and one fingertip capillary blood sample .
bmi : body mass index ; nyha : new york heart association ; lvef : left ventricular ejection fraction ; ckd : chronic kidney disease ; egfr : estimated glomerular filtration rate ; icd : implantable cardioverter defibrillator ; pm : pace - maker ; bnp : b - type natriuretic peptide ; ace - i : angiotensin converting enzyme inhibitor ; arb : angiotensin receptor blocker .
overall , the bnp values obtained ranged between 95 and 2,178 pg / ml using the alere heart check , and between 89 and 1,435 pg / ml using the architect system .
there was a strong positive correlation between the two measurements ( r = 0.947 , p < 0.0001 ) , although the values diverged more when bnp was higher than 1,500 pg / ml ( fig .
bland - altman analysis confirmed this difference ( bias of 46.9 pg / ml ) , some values above 1,500 pg / ml being outside the 95% limit of agreement ( fig .
2 ) . distribution of capillary bnp measured on the alere heart check system according to plasma bnp measured on the abbott architect system among the 111 patients with chf , examined in the study .
we compared both methods for their diagnostic accuracy in distinguishing the asymptomatic chf patients , i.e. belonging to nyha functional class i , from those with symptoms , i.e. belonging to nyha functional classes ii - iii .
the methods ( alere heart check vs. abbott architect ) showed similar diagnostic performances ( figs . 3 and 4 ) with values of area under the curve ( auc ) of 0.983 and 0.984 , respectively , and equivalent sensitivities , specificity , and positive and negative likelihood ratios . in this roc plot
, there is the representation of the very good diagnostic performance ( auc = 0.983 ) of the alere check system as a tool for predicting a clinical picture of chf belonging to nyha classes ii - iv . by adopting this method ,
the best diagnostic accuracy for identifying a condition of nyha class ii or higher has been attributed to the bnp threshold value of 412 pg / ml .
this means that this value , when derived from a measurement made by the alere check system on capillary blood , is associated to the presence of heart failure symptoms with a sensitivity of 95.9% and a specificity of 91.9% ( note on top of the graph ) .
chf : chronic heart failure ; nyha : new york heart association ; roc : receiver operating characteristic ; auc : area under the curve ; bnp : b - type natriuretic peptide ; pg : picogram . in this roc plot
, there is the representation of the very good diagnostic performance ( auc = 0.984 ) of the abbott architect system as a tool for predicting a clinical picture of chf belonging to nyha classes ii - iv .
the criterion value of 438 pg / ml has been identified as the bnp value that exhibits the best diagnostic accuracy for predicting the presence of symptoms of heart failure .
this means that this value , when the bnp measurement is done from plasma using the abbott architect system , is associated with heart failure symptoms with the best combination of sensitivity and specificity ( 91.8% and 96.8% , respectively ) .
chf : chronic heart failure ; nyha : new york heart association ; roc : receiver operating characteristic ; auc : area under the curve ; bnp : b - type natriuretic peptide ; pg : picogram .
we subsequently compared the results from capillary and plasma bnp measurements , according to the nyha functional classification of dyspnea ( figs . 5 - 7 ) .
below there are the pertinent findings , that we have found for each nyha class by measuring the bnp levels in capillary whole blood ( alere heart check system ) and edta plasma from venous sample ( abbott architect system ) respectively , expressed as median plus interquartile range .
there was no statistical difference between capillary and plasma bnp according to the nyha class of patients ( nyha i : 245 pg / ml ( 168.5 - 348.25 ) vs. 251 pg / ml ( 194 - 381 ) ; nyha ii : 610.5 pg / ml ( 500 - 765 ) vs. 578.5 pg / ml ( 495 - 699 ) ; nyha iii : 1,223 pg / ml ( 923.75 - 1,309.75 ) vs. 897 pg / ml ( 802.5 - 1,087.5 ) ) .
comparison of capillary ( alere heart check system ) and plasma ( abbott architect system ) bnp levels in patients with chronic heart failure nyha class i ( n = 62 ) .
comparison of capillary ( alere heart check system ) and plasma ( abbott architect system ) bnp levels in chronic heart failure patients with nyha class ii ( no = 30 ) .
comparison of capillary ( alere heart check system ) and plasma ( abbott architect system ) bnp levels in chronic heart failure patients with nyha class iii ( no = 19 ) .
in this study , we evaluated the clinical performance of a new method for the hematochemical diagnosis of cardiac decompensation at the patient s bedside , the alere heart check system , by comparing it with our standard laboratory method ( abbott architect ) , which measures the plasma bnp .
overall , the alere heart check system showed good performance as evidenced by the good correlation with the results of the abbott architect found in the entire investigated cohort .
due to technical limitations , the poc testing methods are usually less accurate than the automata - based methods for quantifying biomarkers .
the alere heart check system is no exception , and its accuracy falls within the range observed for other pocs measuring bnp at low concentrations of bnp ( table 1 ) . for higher concentrations of bnp ,
the alere heart check system exhibited a relatively high coefficient of variation ( 18% ) compared to other pocs , which is in line with the correlation rather low between the values of capillary ( alere heart check ) and plasma ( abbott architect ) bnp at higher concentrations ( > 1,500 pg / ml ) , as found in nyha class iii ( see also the box - and - whisker plots displayed in figures 5 - 7 ) .
a similar variation , related to the concentration , was also observed in lab - based essays such as the i - stat abbott ( fig .
1 ) . these results suggest that the alere heart check system is an optimal tool for accurate identification of bnp levels , when they are located within its low - to - mid range .
overall , these data strongly suggest that the alere heart check system is reliable for measuring bnp in patients with chf , particularly those within nyha classes i - iii , although important changes to the bnp should be confirmed by lab - based tests . from a practical standpoint ,
this system is the only test for bnp from capillary blood ; the abbott i - stat and the alere triage systems used in emergency departments measure bnp using either venipuncture edta whole blood ( abbott i - stat ) or edta plasma ( alere triage ) .
therefore , the alere heart check is the only non - invasive system that uses capillary blood from the fingertip and could easily be implemented as a rapid method for evaluating bnp by the general practitioner , the community cardiologist or for home monitoring , as evidenced by the recent habit trial .
the differences observed between the two methods ( alere heart check and abbott architect ) are quite small , which suggests that both could be used , in alternation , to follow the efficacy of treatment in patients with chf .
moreover , some ergonomic improvements could be made to facilitate the deposition of the blood droplet on the strip , which would result in fewer errors .
in addition , the machine lacks traceability of the results since patients i d can not be entered into the machine .
importantly , the data we obtained showed the alere heart check bnp assay performed ( auc = 0.983 ) as well as the abbott architect assay ( auc = 0.984 ) in distinguishing patients with asymptomatic ( nyha i ) and symptomatic ( nyha ii - iii ) chf .
these results suggest that the alere heart check bnp assay could be used in an emergency to triage dyspneic patients . however , our data suggest that more studies are needed to validate this method in emergency conditions . indeed , capillary ( alere heart check )
bnp was biased by 46.9 pg / ml ( bland - altman plot in fig .
currently , the algorithm available for the diagnosis of acute decompensated heart failure ( adhf ) in international guidelines refers to a bnp cutoff of 100 pg / ml , i.e. adhf can be excluded in acutely dyspneic patients whose bnp levels fall below this threshold value [ 1 , 2 ] . given the bias observed in our bland - altman comparison , the use of the alere heart check system in emergency conditions will most likely overestimate patients who would fall into the gray zone of the bnp ( 100 - 400 pg / ml ) , among acutely dyspneic patients , unless a new threshold is determined for this system .
first , it was a study based on only two participating centers , with a small population younger than the current population with chf and a few women . however , the range of bnp measured was sufficiently broad to test the limits of the measurements .
compared to other pocs available for blood glucose , inr or plasma bnp , we postulate a higher cost than laboratory - based methods .
however , cost - effectiveness should be evaluated in a larger - scale study , according to the aimed application , e.g. remote vs. in - hospital monitoring .
the alere heart check bnp test is a good poc for the management of heart failure despite a relatively poor precision in higher bnp values .
there was good agreement between the alere heart check system and the lab - based test ( abbott architect system ) .
thus , further studies are required to evaluate the real cost and real application of this device in emergency departments or by patients at home .
the alere heart check bnp test is a good poc for the management of heart failure despite a relatively poor precision in higher bnp values .
there was good agreement between the alere heart check system and the lab - based test ( abbott architect system ) .
thus , further studies are required to evaluate the real cost and real application of this device in emergency departments or by patients at home .
there are no financial disclosures to be reported for the present article and the research work that is described in it .
Output:
| backgroundin recent years , several systems have been implemented to achieve quick and non - invasive measurements of b - type natriuretic peptide ( bnp ) . among them , aleretm heart check ( ahc ) bnp test represents the most recent advancement .
it is a rapid point - of - care ( poc ) immunoassay , projected for measuring bnp directly from a capillary whole blood sample .
this study aimed at comparing the analytical and clinical performances of this new poc to our reference method ( abbott architect system).methodsone hundred eleven patients with stable chronic heart failure ( chf ) referring to one cardiac rehabilitation center were enrolled from december 2013 to may 2015 .
these patients were subjected to a simultaneous capillary ( ahc ) and plasma ( abbott ) bnp measurements .
clinical and analytical performances of ahc were assessed and compared to the reference method.resultscapillary bnp showed a good correlation with the reference method ( r = 0.94 , p < 0.0001 ) , although the values diverged when bnp was higher than 1,500 pg / ml .
indeed , the ahc had a relatively poor precision and the coefficient of variability was 10.1% and 18% for low and high controls , respectively .
however , both methods showed similar diagnostic performances in discriminating the patients with heart failure in new york heart association ( nyha ) class i from those belonging to nyha classes ii - iii , with values of area under the curve ( auc ) of 0.983 and 0.984 , respectively , and equivalent sensitivity , specificity , and positive and negative likelihood ratios.conclusionthe ahc bnp test is a good poc able to provide reliable information about the hemodynamic status of chf patients , especially of those belonging to nyha classes i - iii . |
PubmedSumm118686 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: colorectal cancer is one of the most common causes of morbidity and mortality from malignant tumors of the gastrointestinal tract .
the prevalence of colorectal cancer is increasing in the population of romania , this condition ranking second in the incidence of malignant tumors worldwide .
the most widely used staging of colorectal cancer is that of the american joint committee of cancer ( ajcc ) , known as the tnm staging system . within this
cancer staging , stage n describes the number of lymph nodes invaded by the tumor .
thus , the larger the number of excised lymph nodes , the higher the number of lymph nodes invaded by the tumor , which will result in a more advanced n stage .
the number of excised lymph depends on various factors , being influenced by the surgeon , the pathologist and by factors related to the patient ( immune status , age , tumor location , t stage ) .
there are studies showing that the total number of invaded lymph nodes does not allow accurate staging of colorectal cancer , requiring the identification of other pathological markers which would enable accurate staging for further treatment
. lymph node ratio ( lnr ) is defined as the ratio of the number of metastatic lymph nodes over the total number of resected lymph nodes .
multiple studies confirm the influence of lnr on survival in breast cancer , bladder cancer , pancreatic cancer , gastric cancer and lung cancer .
the study aims to highlight the role and impact of lnr on survival of patients with stage iii colorectal cancer , who underwent radical surgery in our clinic .
to achieve this objective , the evaluation was per - formed on patients with stage iii colorectal cancer who underwent radical surgery at the county clinic hospital , cluj - napoca , 5 surgical clinic , between january 2006 and july 2008 .
patients with histopathological type of cancer other than adenocarcinoma and those with incomplete data or lost from the study were excluded .
the data analyzed were represented by : age , gender , tumor location , stage ( iiia , iiib , iiic ) , t stage , n stage , number of excised lymph nodes , number of invaded lymph nodes , lymph node ratio ( lnr ) .
lnr was calculated by dividing the number of metastatic lymph nodes to the total number of excised lymph nodes .
based on this criterion , patients were divided into 5 groups , the cut - off points where set at < 0.10 , 0.110.21 , 0.220.36 , 0.370.6 , and > 0.61 respectively .
patients were evaluated during a postoperative follow - up period of 5 years , at every 6 months in the first two years and at 1 year over the next three years .
statistical analysis was used in order to calculate cancer - specific survival after 5 years ( 60 months ) and the correlations between the different parameters considered in the study .
the association between qualitative variables was assessed using the chi square test or the fisher exact test .
the normal distribution of data was checked with strip - chart , quantile - quantile plot , shapiro - wilk test .
quantitative data was presented as median and interquartile range ( for non - normally distributed data ) . to check for differences between two independent groups of quantitative data ,
the mann whitney u test ( for non - normally distributed data ) was used .
comparisons between three or more groups regarding quantitative variables were performed with the kruskal wallis test for non normally distributed data .
then , post - hoc pair - wise tests were performed with the tukey kramer test . to evaluate the association between quantitative data we used the spearman correlation coefficient ( for data without normal distribution ) , the test of statistical significance and a scatter plot chart type .
survival data was described by presenting the number of deaths , censored data , the percentage of survival at different points in time and quantiles of survival with associated 95% confidence intervals , respectively graphically by kaplan - meier survival curves .
we calculated the hazard ratio for different explanatory variables to assess their association with survival using cox regression , the hazard and the 95% confidence interval associated with it .
for all the statistical tests the significance level alpha was set at 0.05 and the two - tailed p value was computed .
the statistical analysis was performed in r environment for statistical computing and graphics , version 1.15.1 .
this study was approved by the medical ethical commission of the county clinic hospital , cluj - napoca .
one hundred forty - eight patients with colorectal cancer underwent surgery at the county clinic hospital , cluj - napoca , 5 surgical clinic , between january 2006 and july 2008 .
of these , 49 were stage iii , of which 35 met the inclusion criteria in the study . of these , 14 ( 40% ) were women and 21 ( 60% ) men .
31.4% ( 11 cases ) were aged under 60 and 68.6% ( 24 cases ) were aged over 60 .
the survival of patients aged over 60 was significantly higher than of those under 60 when testing the difference in survival based on age ( by means of both logrank test , p<0.021 and cox regression , p<0.026 ) .
clinical and pathological characteristics of patients and the 5-year survival are shown in table i. in terms of topography , 9 cases were located in the right colon , 11 in the left colon and 15 in the rectum .
the number of lymph nodes excised during surgery for cancer of the right colon was significantly higher ( p<0.001 ) , but when considering the number of 12 nodes excised as a resectability criteria , the number of excised lymph nodes was not statistically significant based on tumor location .
the five - year survival rate , according to the number of excised lymph nodes , is 34.62% in the group with < 12 nodes compared to 45.45% in the group with > 12 nodes , not statistically significant .
the number of malignant lymph nodes is statistically correlated with the five - year survival ( p<0.001 ) .
thus , each unit increase determines a 1.54-fold hazard increase ( 95% ci ( 1.281.85 ) .
the comparison of the relationship between the number of excised lymph nodes and the number of invaded lymph nodes reveals a positive trend ( linear relationship ) , but not confirmed statistically ( spearman correlation coefficient : 0.10431 ( p=0.01431 ) .
the five - year survival by stage was higher in stage iiia cancer ( 75% ) than in stage iiib cancer ( 55% ) ( not statistically significant ) and superior to stage iiic cancer ( 10.71% ) , this time statistically significant ( p<0.006 ) .
survival in t2 group compared to t3 and t4 groups reveals a higher value , but not statistically significant .
the analysis of n stage shows that 21 patients ( 60% ) were n1 stage and the remaining 14 ( 40% ) were n2 stage .
the five - year survival rate in n1 group was 64.62% compared to the n2 group , where it was 8.57% .
the difference was statistically significant for both logrank test ( p<0.001 ) and cox regression ( p<0.001 ) , as shown in figure 2 .
the lymph node ratio ( lnr ) groups consisted of 5 cases ( 14.2% ) in lnr1 group ( < 0.1 ) , five - year survival rate 100% , 6 cases ( 17.14% ) in lnr2 group ( 0.110.21 ) , five - year survival rate 83.33% , 8 cases ( 22.8% ) in lnr3 group ( 0.220.36 ) , five - year survival rate 37.5% , 12 cases ( 34.28% ) in lnr4 group ( 0.370.60 ) , survival rate 0% , and lnr5 group ( > 0.6 ) , survival rate 0% ( figure 3 ) .
the relationship between the five - year survival rates in the five lnr groups results in a statistically significant proportionality ( p<0.001 ) ( logrank ) , as shown in figure 3 .
the association between the five lnr groups and n stage attained a p=0.007 value ( statistically significant ) during fisher s exact test , showing that lnr is associated with n stage ( figure 4 ) .
in patients staged n1 or n2 and divided in subgroups using lnr , five - years survival rates was different between n1 and also n2 stage .
more studies support the importance of the lnr in predicting survival after colorectal cancer resection .
berger et al . , in their study , based on a large number of patients undergoing complete resection and adjuvant chemotherapy for colon cancer , analysed the lnr using groups based on quantiles .
overall survival ( os ) , disease - free survival ( dfs ) and cause - specific survival ( css ) were used as end points .
survival decreased significantly as lnr increased , for all three end points . in their study , vaccaro et al .
, used the same three end points in patients undergoing curative resection for stage iii colon cancer and the results were similar and on multivariate analysis , the number of positive lymph nodes was not found to be a significant predictor of survival . chin et al .
have also found the lnr to be a significant predictor of survival in stage iii colon cancer , but they included only those patients in which 12 or more lymph nodes had been identified by the pathologist .
, in stage iii colon cancer followed for a period of three years . in rectal cancer
the lnr also been shown to be an independent prognostic factor , in studies like perschuad et al . who analysed a number of three hundred seven patient undergoing curative rectal and mesorectal excision .
rosenberg et al . analyzed both colonic and rectal cancers , with the aim of identifying more precise cut - off values for the lnr to increase prognostic value .
the cut - off points for lnr providing the highest level of discrimination to determine survival were 0.17 , 0.41 , and 0.69 .
used receiver operating characteristic ( roc ) statistical analysis to reach a lnr cut - off value of 0.18 , set again the lnr as an independent prognostic indicator for patient with stage iii colorectal cancer following radical resection .
several studies have used various cut - off points for the lnr , most of them determined the cut - off points by using the lnr to draw the kaplan - meier survival curve .
in our study we established the cut - off points of the lnr at < 0.1 ; 0.21 ; 0.36 ; 0.6 ; > 0.61 , applied in previous studies and divided the patients in five groups ( 1 to 5 ) based on cut - off interval and shown a statistically significant proportionality in the relationship between the five - year survival rates and the five lnr groups . according to the results of this study ,
when the patients in n1 and n2 stage were divided by lnr , respectively , the five - year survival rates were different by lnr in patients in the n1 and n2 stage .
this data shows that the patients divided by n staging based on the absolute number of metastatic lymph nodes are not distributed consistently and the use of lnr , along with the current tnm staging , can give a better prognosis . in studies that analyzed patients with stage n
, shows the five - year survival rates of the patients in n2 stage were not different by lnr and that because of cut - off points values chosen .
this demonstrates once again that the cut - off value is not universal and methods used to choose the cut - off vary in each study , although the value of the lnr is widely accepted , appropriate stratification for lnr remains unclear .
thus , if the lnr is to be used as a prognostic factor , a standardization of cut - off points for the lnr is necessary for stratification of stages with better correlation with the prognosis .
the use of lnr , along with the current tnm staging , can better predict the prognosis for n1 and n2 stage colorectal cancer and may be an independent prognostic factor in stage iii colorectal cancer .
future large scale prospective studies are needed to define cut - off points for lnr to play a role as an independent prognostic factor in stage iii colorectal cancer and to allow optimal separation by subgroups of patients and to verify if the lnr could be used to direct adjuvant therapy .
Output:
| aimthe aim of this study was to evaluate the prognostic significance of the lymph node ratio ( lnr ) in patients with stage iii colorectal cancer.materials and methodswe included 35 stage iii colorectal cancer patients who underwent a curative resection at the county clinic hospital , cluj - napoca , 5th surgical clinic between january 2006-july2008 .
patients were categorized into lnr groups 1 to 5 according to cut - off points : < 0.1 ; 0.21 ; 0.36 ; 0.6 ; > 0.61 .
the kaplan - meier and the cox proportional hazard models were used to evaluate the prognostic effect according to the lnr.resultsfrom one hundred forty - eight patients who underwent colorectal cancer resection , 33.1 % were stage iii and 35 patients met the study inclusion criteria . the five - year survival rate in n1 group was 64.62% compared to the n2 group , where it was 8.57% ( p<0.001 ) the lymph node ratio ( lnr ) groups consisted of 5 cases ( 14.2% ) in lnr1 group ( < 0.1 ) , five - year survival rate 100% , 6 cases ( 17.14% ) in lnr2 group ( 0.110.21 ) , five - year survival rate 83.33% , 8 cases ( 22.8% ) in lnr3 group ( 0.220.36 ) , five - year survival rate 37.5% , 12 cases ( 34.28% ) in lnr4 group ( 0.370.60 ) , survival rate 0% , and lnr5 group ( > 0.6 ) .
the relationship between the five - year survival rates in the five lnr groups results in a statistically significant proportionality ( p<0.001).conclusionlymph node ratio can be considered a more accurate and potent modality for prognosis in stage iii colorectal cancer and may improve stratification in this heterogenous group of patients . |
PubmedSumm118687 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: it is believed that long before clinical manifestation , inflammatory t cells specific for antigen structures similar to myelin are activated in the periphery .
such cells cross the blood brain barrier and move into the cns , where they induce inflammatory processes .
therapeutic approaches available today primarily aim at modulating or interfering with these immunological processes . for treatment of relapsing remitting ms ifn - beta
ifn - beta treatment reduces the frequency of clinical exacerbations by approximately 35% and delays the progression of disability .
this is either associated with aberrations in the ifn - i signaling cascade or the presence and/or induction of ifn - beta - neuralizing antibody responses . in particular ,
induction of ifn - beta - neutralizing antibody responses constitute a problem that may turn responders into non - responders .
the incidence of the induction of ifn - beta - specific antibody responses differs among marketed products and presumably is caused by aggregates , oxidated products , trace amounts of product - related impurities and to a lesser extent by differences in the amino - acid composition and post - translational modifications of the product .
considering that ifn - beta treatment may be associated with the induction of adverse effects such as flu - like symptoms , potential liver damage and psychiatric side effects , biomarkers that discriminate responders and non - responders even before initiation of the ifn - beta treatment would be helpful ; however , these are not yet available .
barr virus infection together with a genetic predisposition may be a certain risk factor for disease development , so far the etiology of ms is largely unclear . as patients ' materials , such as blood and brain samples , are not easily assessable , knowledge about how ifn - beta treatment affects autoimmune inflammation within the cns is limited . in the human system ,
this notion is supported by experimental data indicating that upon ifn - beta treatment myelin basic protein - reactive human t - cell clones show reduced activity and a th2 shift .
similarly , upon in vitro ifn - beta stimulation of peripheral blood mononuclear cells and after ifn - beta treatment of healthy volunteers or ms patients , enhanced il-10 expression was detected .
on the other hand , in 60% of ms patients treated with ifn - beta , enhanced percentages of proinflammatory th1 cells were observed that produced ifn - gamma , indicating that ifn - beta may also induce proinflammatory pathways . in more recent studies
it was verified that under ifn - beta treatment not only anti - inflammatory but also th1-associated gene signatures were found . with the discovery of a new inflammatory th subset , th17 cells ,
elevated levels of il-17 have been reported in peripheral blood mononuclear cells , cerebrospinal fluid and active cns lesions of ms patients .
ifn - beta enhances activation - induced apoptosis in th17 but not in th1 cells .
this can be explained by the enhanced ifn - i receptor expression levels in th17 cells compared with th1 cells .
a direct ifn - beta treatment of naive cd4cd45ra t cells cultured under th17-polarizing conditions resulted in downregulation of rorc , il-17a and il-23r , but upregulation of il-10 gene expression , and had no effects on the th1 and th2-associated transcription factors t - bet and gata-3 .
furthermore , ifn - beta - stimulated dc showed a reduced il-23 and il-1 production and an enhanced il-27 secretion . in remitting relapsing ms patients ifn - beta non - responders showed higher il-17f serum levels than responders .
collectively , data showing ifn - beta effects on th1 as well as on th2 and th17 cells indicate that in humans the immunomodulatory function of ifn - beta treatment can not simply be explained by the induction of a th1/th17 to th2 shift , but that more complex mechanisms have a role .
for analysis of ms - associated disease mechanisms the eae in rodents is a broadly accepted animal model . in order to induce eae , mice or rats
are immunized subcutaneously with mog3555 peptide in freund 's complete adjuvant ( cfa ) . typically , 1015 days later , clinical signs of cns autoimmunity manifest that slightly improve with time . in sterile inflammation of the cns
it is generally believed that th1 and th17 cells confer disease , while th2 cells are protective .
more recent data suggest that th1 and th17 cells concomitantly induce autoimmunity and confer different pathogenic processes within the cns .
th17 cells pass through different phases of differentiation , including induction , amplification and stabilization .
induction is mediated by tgf - beta and il-6 , whereas amplification is mediated by il-21 , and terminal differentiation and stabilization is conferred by il-23 .
interestingly , none of the known th17 signature cytokines including il-17a , il-17f , il-21 and il-22 have been found to be mandatory for the development of eae . instead
, granulocyte macrophage colony - stimulating factor that is induced by il-23 fulfills the criteria of an encephalitogenic cytokine . upon
eae induction in ifnar1 mice that are devoid of the ifn - i receptor , clinical signs of autoimmunity became apparent with similar kinetics as observed in wild - type controls .
of note , the overall disease score was significantly enhanced in ifn - i receptor - deficient mice in a manner that even occasional death was observed under conditions where wild - type mice developed only moderate symptoms . furthermore , disease severity remained elevated also at later time points .
these observations were in line with earlier experiments in which ifnb mice devoid of the ifn - beta gene were used for eae studies . in these experiments
also ifnb mice showed enhanced disease and an increased influx of mononuclear cells into the cns .
detected enhanced ifn - beta levels exclusively within the cns but not in the serum of diseased wild - type animals .
these observations are compatible with the model that during the course of eae an ifn - beta response is induced within the cns that locally stimulates cells and thus modulates inflammatory processes within inflammatory foci .
eae studies in ifnar1 mice are limited by the fact that the ifn - i receptor is expressed basically on all cells of the body . to study whether t cells , monocytes , neurons or some other cell type had to be ifn - i - stimulated in order to reduce disease , mice with a cell type - specific deletion of the ifnar1 gene were generated .
this was accomplished by flanking the transmembranic exon 10 of the ifnar1 chain by loxp sites in a manner that upon cre - mediated deletion of exon 10 a frame shift was induced that resulted in a truncated ifnar1 chain devoid of the transmembranic and cytoplasmatic signaling domain .
such ifnar1 mice carrying two conditional alleles showed a similar ifn - i signaling as compared with wild - type mice , whereas conditional mice carrying two alleles with a deleted exon 10 showed an defective ifn - i signaling as observed in ifnar1 mice .
analysis of mice with a cell type - specific ifn - i receptor deletion revealed that ifn - i receptor engagement neither of t cells nor of neurons had a role .
instead , ifn - i receptor signaling of myeloid cells comprising monocytes , macrophages , microglia and granulocytes was critically involved in amelioration of the overall disease score ( for a schematic depiction , see figure 1a ) .
a detailed analysis revealed that ifn - beta stimulation of monocytes reduced lipopolysaccharide ( lps)-induced chemokine production .
furthermore , in mice with a myeloid cell - specific ifnar1 deletion , peripheral myeloid cells showed an overall activated phenotype as also demonstrated by enhanced mhc - ii expression .
similar to the observation in humans , exogenously administered ifn - beta can suppress eae in wild - type mice . in this context , it is interesting that ifn - beta treatment significantly attenuated the progression of eae symptoms in th1-induced eae , whereas the symptoms of th17-induced eae were exacerbated . ifn - i can directly inhibit tgf - beta / il-6-induced th17 development .
this is demonstrated by the fact that ifn - i receptor deficiency resulted in elevated numbers of encephalitogenic th17 cells .
the finding that lps - stimulated bone marrow - derived macrophages or dc devoid of ifn - i receptor showed a defective il-27 production suggested that upon eae induction in ifnar1 mice il-27 responses also were flawed .
as il-27 suppresses differentiation of th17 cells and promotes t cells to secrete il-10 , defective il-27 responses further promote a th2 shift .
as pointed out above , the currently known th17 signature cytokines il-17a , il-17f , il-21 and il-22 have not been found to have a critical role in promoting the development of eae .
instead , il-23-induced th17 cells produce granulocyte macrophage colony - stimulating factor ( gm - csf ) that seems to be important in conferring disease .
this cytokine stimulates invading myeloid cells , which in turn promote and sustain inflammation within the cns . for a better understanding of how the ifn - beta stimulation of myeloid cells affects their responsiveness to gm - csf stimulation ,
similar to ifnar1 mice , ips-1 mice ( also referred to as cardif , mavs or visa ) devoid of the rlh system showed enhanced autoimmune inflammatory disease of the cns . by analogy to the above - discussed experiments with ifnar1 mice , this observation argues for the possibility that ifn - i responses induced by peripheral rlh triggering might show some therapeutic effect .
this therapeutic effect was only observed in ifn - i receptor - competent mice , indicating that ifn - i is the key effector cytokine .
interestingly , engagement of the ifn - i receptor on myeloid cells including monocytes , macrophages , microglia or granulocytes did not account for the suppression of cns autoimmunity upon treatment with rlh ligands . instead ,
ifn - i receptor expression on dcs was essential under such conditions ( for a schematic depiction , compare figures 1b and c ) .
treatment with rlh ligands inhibited proliferation and induced apoptosis of mog3555-specific th1 and th17 cells . of note , the experimental data obtained so far do not support the idea that rlh ligand treatment affects the frequency or the function of cd4foxp3treg cells .
currently , the hypothesis that soluble factors such as ifn - i and il-27 secreted by rlh - stimulated dcs inhibit encephalitogenic t - cell responses is favored .
this was demonstrated in mice with eae disease showing a conditional deletion of the ifn - i receptor on dcs that were no longer responsive to rlh ligand treatment . on the contrary ,
mice with a conditional deletion of the ifn - i receptor on myeloid cells showed even enhanced disease , as observed earlier , and still responded to rlh ligand therapy . in conclusion ,
ifn - i receptor engagement of dcs is crucially required to confer therapeutic effects in the cns , whereas ifn - i receptor engagement of myeloid cells is not required .
these observations are in contrast to the disease - ameliorating effects of ifn - i responses induced in the context of eae pathogenesis , where ifn - i receptor triggering of myeloid cells had a crucial role ( for a schematic depiction , see figure 1 ) .
this can probably be explained by the fact that therapeutic rlh ligand treatment elicits ifn - i responses primarily in peripheral lymph nodes , whereas in eae pathogenesis ifn - beta responses are exclusively observed locally within the cns . of note ,
endogenous ifn - i responses do not induce antibodies against ifn - i , thus ensuring that the efficacy of therapeutic rlh ligand treatment is maintained even after repeated treatments .
analysis of a rodent model of ms revealed the significance of ifn - i in ameliorating autoimmune inflammation within the cns . under such conditions ifn - i receptor engagement of myeloid cells had a critical role in improvement of the overall physical status .
future experiments will reveal which myeloid cell subset , and whether perhaps other professional antigen - presenting cells , has to be ifn - i receptor - triggered in order to confer disease amelioration .
interestingly , rlh - deficient mice showed an as much enhanced autoimmune disease as ifn - i receptor - deficient mice , suggesting that rlh triggering might improve disease . indeed , peripheral treatment with complexed rna of wild - type mice with eae disease induced a significant overall improvement .
this effect was dependent on ifn - i triggering of dcs . considering that approximately 30% of ms patients under ifn - beta therapy develop ifn - beta neutralizing antibody responses that reduce efficacy of ifn - beta treatment ,
the above - summarized results suggest that rlh triggering might be a new strategy to induce ifn - i responses that have an impact on ms and would not induce auto - antibody responses . this is due to the fact that in vivo bioactive ifn - i is freshly produced by stimulated cells and upon secretion
is transported by the lymph or the blood stream to the site of action . in the periphery ,
most of the recirculating ifn - i is absorbed within the liver , resulting in a rapid decay of bioactive ifn - i in the blood within 12 days . before the rlh ligand treatment concept can be further evaluated in patients , it will be of interest to study whether rlh ligand treatment can be modified in a manner that ifn - i responses within the cns are selectively triggered .
rlh ligand treatment of dcs induces ifn - beta as well as ifn - alpha responses
. therefore it might be interesting to study whether rlh ligands can be modified in such a way that only ifn - beta or ifn - alpha responses are elicited and whether both responses would show a similar impact on the disease course .
furthermore , specific targeting of relevant antigen - presenting cells by rlh ligand treatment might be attractive because such a strategy probably would induce less fulminant cytokine responses which would cause reduced overall adverse effects . a detailed analysis of dc - mediated effects that affect the balance between th1/th17 and th2 responses and disease severity would help to further refine potential therapeutic strategies . in conclusion ,
the recent observation that rlh ligand treatment has an ameliorating effect on autoimmune inflammation of the cns in a rodent model might pave the way for new therapeutic strategies of ms by inducing endogenous ifn - i responses .
Output:
| different viruses trigger pattern recognition receptor systems , such as toll - like receptors or cytosolic rig - i like helicases ( rlh ) , and thus induce early type i interferon ( ifn - i ) responses . such responses may confer protection until adaptive immunity is activated to an extent that the pathogen can be eradicated .
interestingly , the same innate immune mechanisms that are relevant for early pathogen defense have a role in ameliorating experimental autoimmune encephalomyelitis ( eae ) , a rodent model of human multiple sclerosis .
we and others found that mice devoid of a component of the ifn - i receptor ( ifnar1/ ) showed significantly enhanced autoimmune disease of the central nervous system ( cns ) .
a detailed analysis revealed that in wild - type mice ifn - i triggering of myeloid cells was instrumental in reducing brain damage .
a more recent study indicated that similar to ifnar1/ mice , rlh - signaling - deficient mice showed enhanced autoimmune disease of the cns as well .
moreover , when peripherally treated with synthetic rlh ligands wild - type animals with eae disease showed reduced clinical scores . under such conditions , ifn - i receptor triggering of dendritic cells had a crucial role .
the therapeutic effect of treatment with rlh ligands was associated with negative regulation of th1 and th17 t - cell responses within the cns .
these experiments are consistent with the hypothesis that spatiotemporal conditions of , and cell types involved in , disease - ameliorating ifn - i responses differ significantly , depending on whether they were endogenously induced in the context of eae pathogenesis within the cns or upon therapeutic rlh triggering in the periphery .
it is attractive to speculate that rlh triggering represents a new strategy to treat multiple sclerosis by stimulating endogenous immunoregulatory ifn - i responses . |
PubmedSumm118688 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: despite decades of effort , schistosoma japonicum ( sj ) remains to be a prevalent schistosome in asia and is the only schistosome causing infection in china .
although fundamental control has been achieved through potent governmental measures , sj infection remains widespread and can not be effectively controlled in some lakes and marshland regions , thus inflicting massive social and economic burdens [ 13 ] .
progressive liver fibrosis is one of the major hallmarks of sj infections and accounts for the further development of portal hypertension , ascites , hepatosplenomegaly , or even liver cirrhosis .
however , the mechanism behind schistosomal liver fibrogenesis and immune response remains poorly understood . as schistosome infection progresses into the chronic phase ,
schistosome eggs that are deposited in tissues begin to secrete soluble egg antigen ( sea ) , which suppresses th1-mediated response and promotes th2-mediated inflammatory reactions .
thus , th2-related cytokines are inferred to participate actively in fibrogenesis and have thus been extensively studied [ 5 , 6 ] .
interleukin- ( il- ) 13 is a cytokine secreted by several cell types , including eosinophils , mast cells , basophils , epithelial cells , smooth muscle cells , fibroblasts , macrophages , and t cells , especially th2 cells .
il-13 participates in asthma , tumorigenesis , and parasitic diseases . in schistosoma mansoni- ( sm- )
liver fibrogenesis is severely decreased in sm - infected il-13-deficient mice , as well as in wild - type animals treated with il-13 antagonists , whereas in tgf-1 and mmp-9 deficient mice , such alleviation effect is not apparent [ 810 ] .
sj has pathological patterns similar to those of sm , but no data have shown that il-13 serves a function in the upstream regulation mechanism of liver fibrogenesis caused by sj infection .
tissue transglutaminase ( ttg ) , as a multifunctional protein , performs a variety of intracellular and extracellular functions , including hydrolyzing gtp , transamidation activity as a catalyzing enzyme , and cross - linking glutamine residues and lysine residues of proteins .
these properties cause ttg to be involved in various physiological processes , which , if regulated inappropriately , can also lead to its involvement in a number of diseases , such as metastatic cancer , coeliac disease , and lung , renal , and liver fibrosis [ 1113 ] .
ttg is overexpressed in both the murine experimental liver fibrosis model and hepatitis c virus - induced human liver fibrosis . rna interference can result in diminution of liver fibrosis and lesser aggregation of fibrotic tissue .
cystamine ( ctm ) can modify cysteine at the active site on ttg in a disulfide interchanging manner , such that the activity of ttg is selectively inhibited .
inhibition of ttg activity by ctm results in the diminution of liver fibrosis induced by ccl4 .
meanwhile , ttg knockout mice with ccl4 intoxication display high lethality as compared with wild - type controls .
therefore , enhanced ttg level seems to protect the liver from acute and chronic injury , but its net effect on fibrogenesis resulting from different causes requires further study .
ttg modulates inflammation , exerting both pro- and anti - inflammatory effects , such as positive feedback loop with tgf-1 .
nf-b , a key inflammation - associated factor , is activated by ttg through the cross - linking of the c - terminal glutamine cluster of iba .
epithelial ttg can induce th17 differentiation and subsequent il-17 production and pulmonary fibrosis in bleomycin - treated mice
. moreover , ttg reportedly regulates th2 cytokine secretion and mediates in vitro and in vivo allergic inflammation [ 20 , 21 ] .
ttg can also downregulate peroxisome proliferator - activated receptor ( ppar ) , as well as increasing the classic parameters of inflammation , such as tnf - alpha , tyrosine phosphorylation , and mapks , in a model of cystic fibrosis . in this study
, we take an important step toward answering these questions by uncovering a novel connection among ttg , il-13 , and sj - caused liver fibrosis .
importantly , we further demonstrate that the treatment of mice with sj - induced liver fibrosis by using an inhibitor of the enzymatic activity of ttg inhibits the sj - induced upregulation of il-13 and alleviates liver fibrosis . to our knowledge , these findings show that ttg is involved in the development of sj infection - induced liver fibrosis in mice , and the mechanism may be associated with ttg - regulated il-13 expression .
this study was performed in strict accordance with the recommendations in the guide for the care and use of laboratory animals of state scientific and technological commission .
the protocol was approved by the committee on the ethics of animal experiments of guangzhou medical university .
all surgeries were performed under sodium pentobarbital anesthesia , and every effort was made to minimize suffering .
six- to eight - week - old female balb / c mice ( experimental animal center of sun yat - sen university , guangzhou , china ) were infected percutaneously through the abdomen with 20 3 sj cercariae .
the mice livers were collected and determined at weeks 5 , 6 , 8 , and 12 after infection .
louis , usa ) is a common ttg inhibitor [ 15 , 16 , 23 , 24 ] . in this study , for the mice group with ttg inhibitor - ctm treatment , starting at day 3 after infection
, mice were administered with 100 l of ctm ( 10 mm , sigma ) in phosphate - buffered solution ( pbs ) through intraperitoneal injection once per day for 7 d , whereas the infection control group received pbs alone .
the liver tissue sections were stained by mt staining to evaluate collagen content and distribution .
the collagen fibers were stained blue , cell nuclei were stained black , and the background was stained red .
percentage of total areas with collagen positive color ( blue ) [ percentage of collagen area ( positive blue color area / total area)% ] was analyzed using image - pro plus 6.0 software .
total rna was extracted from fresh liver tissue homogenized in trizol reagent ( invitrogen ) according to the manufacturer 's protocol .
reverse transcriptase ( rt ) reactions for cdna synthesis were performed using primescript rt master mix ( takara ) .
relative mrna expression level was determined by real - time quantitative polymerase chain reaction ( q - pcr ) with sybr green i pcr master ( takara ) kit on abi 7500 machine according to the manufacturer 's protocol .
the primers used were as follows : mouse - il-13 ( forward : cggcagcatggtatggagtg , reverse : attgcaattggagatgttggtcag ) ; mouse - ttg ( forward : 5-gtgagccgtgctatctgtcctg-3 , reverse : 5-actgcctgcttggaacctgaa-3 ) ; mouse - gapdh ( forward : 5-tgtgtccgtcgtggatctga-3 , reverse : 5-ttgctgttgaagtcgcaggag-3 ) .
the q - pcr results were expressed as fold amplification using the 2 method , with mouse gapdh as the internal control .
peripheral venous blood was collected by cutting the tail veins of mice . after being incubated in room temperature for 1 h
, blood samples were centrifuged ( 1000 g , 4c ) for 1015 min .
louis , usa ) and hyaluronic acid ( mouse hyaluronic acid elisa kit , shanghai yueyang biological technology co. , ltd . ) through elisa measurement .
after sacrifice , the mouse livers were immediately fixed in 4% paraformaldehyde and then paraffin - embedded .
anti - il-13 ( af-413-na , r&d systems ) , antismooth muscle actin alpha ( -sma ) ( bm0002 , boster ) , or anti - ttg ( sc-20621 , santa cruz biotechnology ) primary antibody was diluted in 50-fold .
il-13 , -sma , and ttg expressions were detected using gtvision ii detection system / mo&rb ( gene tech ( shanghai ) co. , ltd . ) according to the manufacturer 's instructions .
fresh mouse livers were ground into powder in liquid nitrogen , and moderate protein lysis solution ( ripa : pmsf = 100 : 1 ) was added . after incubation on ice for 30 min , tissue debris was removed by centrifugation ( 15 min , 4c ) .
total protein was resolved by sds - page and then transferred to a polyvinylidene fluoride membrane ( 0.2 m , millipore ) . after blocking with
the antibodies used were as follows : anti - gapdh ab ( cell signaling technology ) , anti--sma ( bm0002 , boster ) , anti--sma ( bm0002 , boster ) , and anti - ttg ab ( sc-20621 , santa cruz biotechnology ) .
the transglutaminase ( tgase ) activity of liver tissue lysates was determined through a modified nonradioactive microtiter plate assay .
briefly , the microtiter plates were coated with 100 l of n , n-dimethylcasein ( sigma , 10 mg / ml to 20 mg / ml ) at 4c overnight , and the wells were blocked with nonfat dry milk ( 0.5% in 0.1 m tris - hcl , ph 8.5 ) for 30 min .
the wells were then washed twice with 350 l of 0.1 m tris - hcl ( ph 8.5 ) .
the following reagents were added to each well to obtain a total volume of 50 l per well : 5 mm cacl2 , 10 mm dithiothreitol , 0.5 mm 5-(biotinamido)pentylamine , 0.4 g lysates of liver tissue , and 0.1 m tris - hcl ( ph 8.5 ) .
the liquid was then discarded , and the reaction was stopped by washing twice with 350 l of 5 mm of edta , followed by washing twice with 350 l of 0.1 m tris - hcl ( ph 8.5 ) .
streptavidin - horseradish peroxidase conjugates were diluted at a proportion of 1 : 200 with nonfat dry milk ( 0.5% in 0.1 m tris - hcl ( ph 8.5 ) ) prior to the addition of 60 l of solution per well to be incubated for l h at room temperature .
the plate was washed once with 350 l of 0.001% triton x-100 followed by washing for four times with 350 l of 0.1 m tris - hcl ( ph 8.5 ) .
then , 100 l of substrate solution ( tmb , sigma t0440 ) was added to each well .
after incubation at room temperature for 10 min , the reactions were stopped by the addition of 25 l of 3 n hcl to each well , and the proteins into which the 5-(biotinamido)pentylamine was incorporated were quantified by measuring the absorbance at 450 nm in a plate reader ( biotek ) .
the relative tgase activity was determined using the absorbance at 450 nm ( od450 ) .
all statistical analyses were performed using spss13.0 software . statistical significance ( p < 0.05 ) between the means of two groups
statistical comparisons of the means of multiple ( > 2 ) groups were determined using repeated - measure one - way anova .
all data were expressed as means sd , and all experiments were repeated twice or thrice .
babl / c mice were infected cutaneously with 20 3 sj cercariae of chinese mainland strain , and mice liver tissues were collected at weeks 0 , 5 , 6 , 8 , and 12 after infection with sj .
liver granuloma and fibrosis were evaluated by monitoring the liver manifestation , area of collagen fiber ( stained blue in mt staining ) ( figure 1(a ) ) , level of serum hyaluronic acid ( figure 1(b ) ) , and strength of -sma - positive staining as a marker of hepatic stellate cell ( hsc ) activation ( figure 1(c ) ) .
sj liver granuloma began at week 5 , and then fibrosis progressed the most seriously at week 8 , whereas chronic liver fibrosis appeared at week 12 . to evaluate the correlation between il-13 and liver fibrogenesis , hepatic il-13 expression profile in both sj - infected mice and normal control
gel analysis result showed that il-13 maintained a relatively low basal expression in the liver of normal control mice but increased significantly after sj infection ( figure 2(a ) ) .
this phenomenon was verified further by q - pcr using the same rna specimens ( figure 2(b ) ) and by elisa to test serum il-13 levels ( figure 2(c ) ) .
these results showed that , in response to sj infection , il-13 was highly expressed whether in liver tissue or peripheral venous blood .
il-13 did not reach a high level of expression until the infection advanced into its late phase , when egg - laying commenced .
the mrna level of il-13 began to drastically increase since week 5 and reached as high as fivefold in week 12 compared with the noninfected control .
we also performed an ihc assay to monitor il-13 expression in liver tissue ( figure 2(d ) ) . at week 5 , the extracellular matrix was distorted , and cells in liver tissue became disorganized , indicating the beginning of granuloma formation and hepatic fibrosis ( figure 1 ) . during this time , il-13 began to be detected in these damaged tissues ( figure 2(d ) ) .
this observation signified the possible function of il-13 in granuloma formation and in the early stage of hepatic fibrogenesis .
an interesting finding was that a high level of il-13 appeared around the granuloma in the area of inflammatory cell infiltration , especially at week 8 after sj infection , but cells around the veins where sj adult worms were located did not exhibit il-13 positive staining ( figure 2(d ) ) . given the central function of granuloma in hepatic fibrosis , these findings implied that il-13 around the sj egg granuloma was induced by the host inflammatory response to the stimulation of sj sea and , thus , accelerated granuloma formation and hepatic fibrosis in sj infection .
the involvement of ttg in liver fibrosis has long been suggested [ 13 , 14 , 16 , 17 ] , and our findings are consistent with those of numerous past experiments .
we sacrificed mice at weeks 0 , 5 , 6 , 8 , and 12 after sj infection .
the rt - pcr and q - pcr results showed that ttg mrna expression levels were markedly increased in the liver after sj infection compared with uninfected mice ( figures 3(a ) and 3(b ) ) , as well as ttg protein expression level ( figure 3(c ) ) and total tgase activity ( see figure s1 in supplementary material available online at http://dx.doi.org/10.1155/2014/753483 ) .
furthermore , in sj - infected mouse liver sections , ttg expression was found in the hepatic cells around the hepatic sinusoids where sj adult worms were located or around and in the liver granuloma and fibrosis areas where sj eggs were deposited ( figure 3(d ) ) . to provide further evidence that ttg affects the development of sj - infected mouse liver fibrosis
, we treated the infected mice by using an intraperitoneal injection of ctm once per day for 7 d starting at day 3 after infection . considering that liver fibrosis was the most severe at week 8 after infection ( figure 1 ) , we sacrificed the ctm - treated infected mice and the infected mice without ctm treatment at week 8 .
liver fibrosis was evaluated by monitoring the area of collagen deposition , serum hyaluronic acid level , and strength of -sma - positive staining by ihc assay . compared with those of untreated mice , the liver tissues of ctm - treated sj - infected mice showed significantly lower ttg expression ( figure 4(a ) ) and tgase activity ( figure s2 ) , as well as -sma expression level ( figures 4(b ) and 4(c ) ) , the area size of collagen deposition ( p < 0.001 ) ( figure 4(d ) ) , and serum hyaluronicacid level ( figure 4(e ) ) .
considering that il-13 and ttg are involved in liver fibrosis after sj infection , we tested the level change of il-13 after ctm treatment
. ctm showed a marked effect on il-13 mrna expression . while il-13 was highly upregulated in sj - infected mice , administration of ctm significantly decreased the mrna expression of il-13 in sj - infected mouse livers ( figure 5(a ) ) .
meanwhile , il-13 level in peripheral venous blood was also decreased by 21.6% ( figure 5(b ) ) .
these results showed that ctm can downregulate il-13 in case of sj infection , at least partially , which provided a possibility that il-13 expression can be upregulated by ttg .
liver fibrosis caused by sj is one of the most serious pathological changes that may induce loss of liver function and liver cancer . owing to the early , aggregate , and massive egg - laying characteristics of sj , liver fibrosis symptoms caused by sj are the most grievous among those of the prevalent schistosomiasis .
hence , finding effective measures to prevent or even reverse liver fibrosis is critical in the battle against sj .
however , safe drug intervention will be impossible before we truly understand the immunopathogenesis and mechanism of liver fibrosis of this disease .
il-13 is thought to be the key mediator of liver fibrosis in sm , as antagonizing il-13 or il-13 mouse liver fibrosis was abrogated [ 8 , 9 ] . although the correlation between il-13 and liver fibrosis in sm has been found , more research is required for further assessment of the mechanisms by which il-13 influences liver fibrogenesis .
nevertheless , our findings serve as a basis for studying the function of il-13 in infiltrating lymphocytes in case of sj infection .
while most studies report the positive involvement of ttg in liver fibrosis , contradicting reports still exist .
most studies on the fibrogenesis function of ttg were performed on a carbon tetrachloride - induced liver fibrosis model [ 16 , 17 ] and may thus fail to represent the fibrogenesis mechanism in many other pathological circumstances . in this study
, we provided several lines of evidence suggesting that ttg accelerated sj - induced liver fibrosis .
first , ttg level was consistent with the extent of liver granuloma and fibrosis after sj infection .
ttg was mainly overexpressed in hepatic cells at week 5 and in the hsc at week 6 and mainly in the infiltrating cells around sj eggs at weeks 8 and 12 ( figure 3 ) .
second , the blocking of ttg activity by ctm treatment from days 3 to 10 after sj infection alleviated liver fibrosis ( figure 4 ) . the dose and the duration of ctm treatment
we tried to treat the infected mice at week 5 or 6 with ctm once a day for 7 d or 14 d , but the extent of fibrosis and also the level of tissue transglutaminase exhibited no change ( data not shown ) .
the underlying role and mechanisms of ttg involvement in the pathogenesis of sj infection are unclear .
these data suggest that hsc activation , as well as some inflammatory factors or secretory factors of sj origin , may be the downstream targets of ttg . however , once the downstream pathways or cascades were initiated at the early stage of sj infection , ttg inhibition could not reverse the pathologic changes .
further studies are needed to determine the detailed pathogenesis of ttg contribution to liver fibrosis after sj infection .
the association of ttg with cytokines , such as il-6 , il-17 , il-33 , tgf-1 , tumor necrosis factor alpha , and interferon gamma , had been reported .
ttg is an important inflammatory and fibrogenetic factor involved in th17 and th2 responses .
we found that ttg partially regulates il-13 in immunological response , but the underlying mechanisms of ttg regulation of il-13 require further study .
therefore , we propose a model to illustrate the possible mechanisms linking ttg , il-13 , and liver fibrosis . when exposed to repetitive damage ( viral , parasitic , toxic , and metabolic ) , the liver reacts with a chronic wound healing response that usually results in fibrosis .
liver fibrogenesis is mainly driven by activated hscs and an excess accumulation of extracellular matrix .
the high extent of ttg expression and activity consequently activates nf-b signaling . the activated nf-b signaling pathway upregulates the production of some inflammatory cytokines , including il-6 , il-17 , and il-13 .
meanwhile , by activating th2 response , ttg may enhance the production of il-13 by activating th2 .
these findings suggest that both ttg and il-13 can be drug targets for schistosomiasis liver fibrosis and that selective ttg inhibitory drug and downstream inhibition reagents may abrogate the liver fibrogenesis possibly by regulating il-13 .
further studies on the exact mechanisms of the ttg regulation of il-13 during sj infection are needed .
however , we have to consider that the il-13 level in peripheral venous blood was only decreased by 21.57% .
some compensatory mechanisms can possibly increase the level of il-13 in the blood but not in the liver or some other factors aside from ttg may regulate il-13 expression correlating with liver fibrosis after sj infection .
our data established a novel link among il-13 , ttg , and liver granuloma and fibrosis .
the important function of il-13 and ttg in sj liver fibrosis makes them potential drug targets in preventing liver fibrogenesis .
Output:
| schistosomiasis , one of the most devastating parasitic diseases , is caused by schistosoma japonicum ( sj ) infection resulting in serious liver fibrosis .
interleukin- ( il- ) 13 , which is produced by th2 cells , is a critical profibrotic cytokine found in various organs , including the liver .
tissue transglutaminase ( ttg ) , a group of multifunctional enzymes , serves a central function in the pathogenesis of chronic liver diseases .
however , the relationship between il-13 , ttg , and liver fibrosis during schistosoma infection has not been established .
this study investigated the involvement of il-13 and ttg in liver fibrogenesis during sj infection in mice .
five weeks after sj infection , granuloma and fibrosis development in the liver coincided with an increase in il-13 and ttg in the liver and the upregulation of serum il-13 in infected mice .
administration of cystamine , an inhibitor of ttg , abrogated the increase in both ttg and il-13 in infected mice and ameliorated liver fibrogenesis and granuloma development .
this result establishes a novel link among il-13 , ttg , and liver granuloma and fibrosis under sj infection .
based on their important functions in liver fibrosis induced by sj infection , il-13 and ttg could be promising potential drug targets against schistosomiasis . |
PubmedSumm118689 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: vincristine ( vcr ) is a mitotic inhibitor antineoplastic agent that is used mainly in combination chemotherapy regimens for acute and chronic leukemia , lymphomas , including hodgkin 's disease and non - hodgkin 's lymphomas , and multiple myeloma .
posaconazole ( psz ) is an oral triazole antifungal used in the treatment of severe oropharyngeal candidiasis , invasive aspergillosis , and other fungal infections in patients who are resistant to , or intolerant of , other antifungal drugs .
psz is also given for prophylaxis in patients who are at high risk for invasive fungal disease due to immunosuppression , such as haematopoietic stem cell transplant recipients with graft - versus - host disease , or those with haematological malignancies with prolonged neutropenia as a result of chemotherapy [ 1 , 2 ] .
the coadministration of azoles ( as prophylaxis or treatment of fungal infections ) and vcr has been shown to increase vcr neurotoxic effects due to the inhibition of cytochrome p450 ( cyp ) isoform 3a4 , for which vcr is a substrate .
in addition , few case reports have illustrated the possible exacerbation of vcr toxicity by coadministration of psz in children and young adults where fluctuations in level of consciousness and seizures have been observed .
psz has been determined in human plasma samples using capillary electrophoresis , hplc with fluorescence detection , and hplc - tandem mass spectrometry ( hplc - ms - ms ) methods [ 7 , 8 ] . additionally , the simultaneous determination of azole antifungals including psz in plasma / serum samples gained a growing interest in the past few years .
different chromatographic methods have been described for this task such as micellar electrokinetic chromatography ( mekc ) and several liquid chromatographic methods coupled with tandem mass spectrometry [ 10 , 11 ] , fluorescence detection , and uv detection [ 1316 ] . on the other hand , estimation of vcr in plasma samples
has been carried out using hplc - uv detection [ 17 , 18 ] , uplc - ms - ms , and several hplc - ms - ms methods [ 2023 ] . besides , an hplc - ms - ms method was presented for the simultaneous determination of vcr and actinomycin - d in human dried blood spots .
in addition , quantification of intracellular vcr concentrations in children with acute lymphoblastic leukemia has been described using hplc with electrochemical detection procedure . moreover
, capillary zone electrophoresis coupled with electrochemical detection has been employed to study the uptake kinetics of vcr by human erythrocytes .
finally , pharmacokinetics of psz and vcr in rats have been separately discussed in only two published reports [ 27 , 28 ] .
although psz - vcr drug - drug interaction has been exposed in several previous reports , the concurrent determination of psz and vcr has not been tackled yet since no analytical reports can be found in the literature . in this report
, we describe the first simple and reliable rp - hplc with diode array detection procedure for the simultaneous determination of psz and vcr in rat plasma .
the structurally related azole antifungal drug ( itraconazole , itz ) has been used as an internal standard .
the proposed method has been applied in a preliminary pharmacokinetics drug interaction study in rats .
an analytical method capable of simultaneously measuring two drugs would be a valuable tool , facilitating the measurement of pharmacokinetics using a single blood draw for each time point with no need to split the sample for processing through two assay methods .
in serial blood collection studies involving rats , in particular , this is an important consideration due to the need to keep cumulative blood volume withdrawal to a minimum .
posaconazole and vincristine sulfate powders ( purity > 99% for both ) were purchased from selleckchem ( houston , tx , usa ) .
hplc grade methanol and acetonitrile ( fisher scientific uk limited , loughborough , leicestershire , uk ) , analytical grade potassium dihydrogen orthophosphate ( riedel - de - han , germany ) , and high purity distilled water were used .
noxafil oral suspension labeled to contain 40 mg / ml psz ( patheon inc . , ontario , canada , ) was purchased from schering - plough s.a .
vincarine vials labeled to contain 1 mg / ml vincristine sulfate solution ( eimc united pharmaceuticals , badr city , cairo , egypt ) were obtained from the local market .
the hplc - dad system consisted of agilent 1200 series ( autoinjector , quaternary pump , vacuum degasser and diode array , and multiple wavelength detectors g1315 c / d and g1365 c / d ) connected to a computer loaded with agilent chemstation software ( agilent technologies , santa clara , ca , usa ) .
the chromatographic separation was achieved using a hc - c18 ( 4.6 250 mm , 5 m particle size ) column attached to hc - c18 ( 4.6 12.5 mm , 5 m particle size ) guard column ( agilent technologies , santa clara , ca , usa ) .
the gradient elution composed the mobile phase : acetonitrile and 0.015 m potassium dihydrogen orthophosphate ( 30 : 70 to 80 : 20 , linear over 7 minutes ) pumped at 1.5 ml / min .
a 10 mg / l stock solution of the internal standard ( itz ) was prepared in methanol . to prepare samples for the calibration curves and validation assessment , three working standard solutions ( 10 , 1 , and 0.1 mg /
l ) of psz and vcr were prepared freshly by successive 1/10 dilutions of the stock solutions with methanol .
the itz ( 0.03 ml ) was added to each 0.2 ml rat plasma sample in a glass test tube . to the rat plasma sample , 0.03 ml of 0.1 m naoh and 6 ml of diethyl ether were added .
because methanol was present in the standard curve samples , an equivalent amount was added to the test samples as well ( 0.2 ml ) .
the tubes were covered , vortex - mixed for 2 min at high speed , and then subsequently centrifuged for 10 min at ~2500 g .
the organic layer was transferred to new glass tubes and evaporated to dryness in vacuo ( christ rotational vacuum concentrator , germany ) .
the residues were reconstituted in 100 l methanol of which 80 l volumes were injected into the hplc .
the plasma recoveries were determined for psz , vcr , and itz at concentration level 2500 ng / ml in rat plasma using four replicates for each concentration .
the extraction efficiency was determined by comparing the peak areas of each analyte to the peak areas of the same amounts directly injected to the instrument without extraction .
calibration curves were constructed using samples of 0.2 ml rat plasma containing psz , vcr , and is .
the curve ranged from 50 to 5000 ng / ml for both psz and vcr . the ratios of psz and vcr peak areas to is peak area were calculated and plotted versus the expected psz or vcr concentrations .
owing to the wide range of concentrations , the calibration curve data were weighed by a factor of 1/x
for both drugs .
intraday accuracy and precision of the assay were determined using four sample replicates of 50 , 500 , and 2500 ng / ml for each of psz and vcr in rat plasma in the same day .
the same concentrations were analyzed in three separate days for assessment of the interday accuracy and precision . for each daily run ,
concentrations were determined by comparison with a calibration curve prepared simultaneously on the same day of analysis .
precision was determined using percentage coefficient of variation ( cv% ) and bias was assessed using percentage error of the mean .
to evaluate the applicability of this method in vivo , two rats ( 200250 g ) were given 40 mg / kg psz orally followed by 0.1 mg / kg vcr i.v . through the tail vein after 30 min of oral dosing .
the protocol was approved by the ethics committee , faculty of pharmacy , alexandria university . on the day before the pharmacokinetic study ,
food was withheld overnight . on the next morning , animals were transferred to metabolic cages to conduct the pharmacokinetic experiments .
serial blood samples were collected at 0.50 , 0.75 , 0.92 , 1.33 , 2.0 , 3.5 , 6.0 , 8.0 , 24.0 , 48.0 , and 72.0 h after oral psz dose using retroorbital sampling .
plasma was separated by centrifugation of the blood at ~2500 g for 3 min .
the elimination rate constant ( z ) was calculated by subjecting the plasma concentrations in the terminal phase to linear regression analysis .
auc0 was calculated using the combined log - linear trapezoidal rule from time 0 h after dose to the time of the last measured concentration , plus the quotient of the last measured concentration divided by z .
dosing ( c
o ) was estimated by back extrapolation of the log - linear regression line using the first three measured plasma concentrations to time 0 .
the clearance was calculated as the quotient of dose to auc0. all compiled data were reported as mean sd unless otherwise indicated .
vcr , psz , and itz eluted at retention times 5.9 , 8.3 , and 10.4 min , respectively ( figure 1 ) .
the three peaks were almost symmetrical with excellent baseline separation and no interferences from endogenous substances in plasma . the column separation factor ( ) and resolution factor for vcr and psz
were calculated to be 1.58 and 14.5 for vcr and 1.32 and 7.95 for psz , respectively .
the column capacity factors ( k ) for vcr , psz , and itz were calculated to be 2.43 , 3.83 , and 5.05 , respectively .
the vcr extraction efficiency recovery was found to be 75.7 5.4% while psz and itz showed 103.9 3.1% and 103.6 5.4% ( ~100% ) recovery , respectively .
the assay linearity for vcr and psz calculated by measuring the peak area ratios of analyte : internal standard within the concentration range of 50 to 5000 ng / ml showed high linearity with a mean r
0.997 for both drugs ( figure 2 ) . the mean weighted slope and
intercept were found to be 0.0007 5.09 10 and 0.315 0.375 for psz , respectively , and 0.0004 0.0002 and 0.002 0.0037 for vcr , respectively .
the validation data showed the assay to be sensitive , accurate , and precise , with the intraday and interday cv% values less than or equal to 13.2% and 8.78% for both drugs , respectively ( table 1 ) .
since both cv% of interday and intraday assessment and interday mean error yielded values less than 20% at the lowest concentration tested , the lower limit of quantitation ( llq ) based on 0.2 ml of rat plasma was 50 ng / ml for both drugs . in both rats
dosed with 40 mg / kg psz orally followed by 0.1 mg / kg vcr i.v .
0.5 h later , the psz showed higher plasma concentrations than vcr at all time points ( figure 3 ) .
the psz cmax for the two rats were 2344 and 1056 ng / ml and the vcr c
o were 376 and 228 ng / ml , respectively .
the psz auc0 were 206459 and 67744 ngh / ml , whereas the vcr auc0 were 2347 and 2568 ngh / ml for rat 1 and rat 2 , respectively .
the psz tmax was found to be 8.4 and 7.8 h for both rats 1 and 2 , respectively .
the vcr clearance and half - life were calculated to be 0.043 l / h / kg and 19.2 h for rat 1 and 0.038 l / h / kg and 14.8 h for rat 2 , respectively .
the assay managed to measure the plasma concentrations for both drugs up to 72 h after dose .
this paper demonstrates an easy , rapid , sensitive hplc assay for the simultaneous determination of vcr and psz in rat plasma .
it successfully measures their plasma concentrations and calculates their pk parameters up to 72 h after dose .
it is worth mentioning that the assay was applied by 3 different analysts on two different hplc apparatus and yielded similar results with minor changes in retention times and total runtime .
the assay was also successfully applied to determine both drugs ' concentrations in other matrices , rat 's liver tissue homogenate , hyperlipidemic rat 's plasma , and liver tissue homogenate , in addition to sorenson buffer ( ph = 7.4 ) , with excellent linearity and same limit of quantification ( data not shown ) . during assay optimization
, the authors utilized the exact chromatographic conditions that they recently published for the hplc determination of psz in bulk form and suspension dosage form .
however , hc - c18 instead of zorbax sb - c18 column was utilized and hc - c18 guard column was added . despite the fact that vcr was detected at 262 nm ( figure 1 ) , it showed better sensitivity and yield at the short wavelength 220 nm .
this demonstrates the importance of the multiple wavelength detector ( dad ) which offers the advantage of measuring each analyte at its optimum wavelength , thus improving sensitivity . during the optimization of the extraction procedures
, the authors tried the direct protein precipitation method and liquid extraction using diethyl ether , ethyl acetate , or methylene chloride .
however , the extraction procedure was preferred to protect the column materials and for the ease of the evaporation step in vacuo compared to the direct protein precipitation one .
solid phase extraction was not attempted due to its relatively higher cost when working with large number of samples within the future planned pk studies .
the psz and vcr retention times using our simultaneous assay lie within the reported retention times for psz and vcr , respectively [ 1318 ] .
there is a slight interference from an endogenous plasma peak in the psz peak ; this interference resulted in the fact that we could not quantify the psz peak accurately below the 50 ng / ml concentration ; however , as mentioned before , it did not interfere with any of the validation parameters within our concentration range 505000 ng / ml . the pharmacokinetics parameters reported for psz and vcr in rat were compared to the only two similar manuscripts found in literature [ 30 , 31 ] .
the vcr clearance came within the lower border of that reporting 0.12 0.08 l / h / kg and showed similar terminal phase half - life to that reporting 14.3 6.3 h .
. the slight variability could be due to the concomitant administration with vcr or difference between our sd rats and the crl : cd br reported .
it is worth mentioning that , for the future planned elaborated vcr - psz drug interaction study , the design of the drug interaction needs to be modified to mimic the actual conditions occurring in humans .
however , for the purpose of proving the appropriateness of the analytical technique to study such interaction , we successfully dosed only a single dose of each drug and managed to measure it using our dad detector for up to 72 h which is advantageous over similar hplc - dad assays reported for each drug alone .
this paper describes the first validated method for the simultaneous determination of posaconazole and vincristine in rat plasma .
the proposed hplc - dad method has been applied in the investigation of their pharmacokinetics in rats up to 72 h after dose .
the obtained pharmacokinetics parameters for posaconazole and vincristine are in good agreement with those reported in previous reports .
the developed method is simple , sensitive , and suitable for the estimation of both drugs in comprehensive drug - drug interaction pharmacokinetic studies in rats .
Output:
| purpose . developing a validated hplc - dad method for simultaneous determination of posaconazole ( psz ) and vincristine ( vcr ) in rat plasma
. methods .
psz , vcr , and itraconazole ( itz ) were extracted from 200 l plasma using diethyl ether in the presence of 0.1 m sodium hydroxide solution .
the organic layer was evaporated in vacuo and dried residue was reconstituted and injected through hc - c18 ( 4.6 250 mm , 5 m ) column . in the mobile phase , acetonitrile and 0.015 m potassium dihydrogen orthophosphate ( 30 : 70 to 80 : 20 , linear gradient over 7 minutes ) pumped at 1.5 ml / min .
vcr and psz were measured at 220 and 262 nm , respectively .
two sprague dawley rats were orally dosed psz followed by iv dosing of vcr and serial blood sampling was performed .
results .
vcr , psz , and itz were successfully separated within 11 min .
calibration curves were linear over the range of 505000 ng / ml for both drugs .
the cv% and % error of the mean were 18% and limit of quantitation was 50 ng / ml for both drugs .
rat plasma concentrations of psz and vcr were simultaneously measured up to 72 h and their calculated pharmacokinetics parameters were comparable to the literature . conclusion .
the assay was validated as per ich guidelines and is appropriate for pharmacokinetics drug - drug interaction studies . |
PubmedSumm118690 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: the
addition of free radicals to nitrones yields a persistent aminoxyl - based
spin adduct that can be detected and characterized by electron paramagnetic
resonance ( epr ) spectroscopy .
spin trapping by epr spectroscopy is
a popular method for the detection of free radicals in chemical and
biological systems .
-phenyl - n - tert - butyl nitrone ( pbn ) and its derivatives
are widely employed as spin traps in in vitro , in vivo , and ex vivo
systems . aside from their application as spin traps ,
nitrones have also exhibited a variety of protective properties in
animal models against oxidative stress - mediated injury .
however , despite the promising pharmacological properties of pbn ,
the molecular mechanism of its action is not well understood . of the
many pbn derivatives that have been synthesized over the years
, disodium
[ ( tert - butylimino)methyl]benzene-1,3-disulfonate n - oxide ( nxy-059 ) has gained the most attention since it
is the first neuroprotective agent to reach phase 3 clinical trials
in the usa .
although it has been suggested
that the radical trapping properties of nxy-059 is the basis of its
neuroprotective action , experimental evidence suggest other possible
mechanisms are involved .
one of the promising strategies in
the design of novel nitrone - based
spin traps is to selectively target these compounds in relevant sites
of radical production , mainly the mitochondrial electron transport
chain , the cytosol , and the membrane - bound nad(p)h oxidase .
selective targeting is usually achieved by conjugating the nitronyl
group to specific target ligands , and therefore , the choice of linker
groups for optimal spin trapping properties is highly desirable . in
addition to the types of ligands that are tethered to nitrones
, it
has been demonstrated that the nature of the linker group also affects
its bioactivity . only a relatively
limited number of n - tert - butyl substituted
nitrones have been synthesized over
the past few years , with functionalization of the aromatic ring being
the most facile method .
several n - tert - butyl - substituted pbns have been synthesized , such as n - benzylidene-1-diethoxyphosphoryl-1-methylethylamine n - oxide ( ppn),n - benzylidene-1,1-bis(ethoxycarbonyl)ethylamine n - oxide ( deepn ) , and the amide
amphiphilic nitrones developed by our group ( lpbnah ) , ( figure 1 ) , but the effect of the
substituents on the electronic properties of the nitrones and their
reactivity with radicals such as o2 are not known .
the substituent effect on the reactivity of dmpo - type
cyclic nitrones has been extensively studied through experimental
and computational approaches , demonstrating the nucleophilic
nature of o2 addition to c-5-substituted
dmpo nitrones .
therefore , derivatization
of the tert - butyl group of the pbn may exhibit electronic
properties that enhance o2 addition
to nitrones and offers opportunities for multifunctionalization of
the spin trap for subcellular target specificity and controlled delivery
in in vitro and in vivo systems .
our previous computational and kinetic studies showed that
para
substitution by electron - withdrawing substituents in pbn gave no significant
polar effects on their reactivity toward o2 , while with ho2 , a more pronounced
increase in the kinetics of addition was observed , indicating the
electrophilic nature of this reaction .
our current goal is to explore
the reactivity of various n - tert - butyl - substituted phenyl nitrones so as to identify the most optimal
linker groups . through optimization of the linkers
, we would be able
to design selective targeted nitrone - based spin traps with improved
reactivity toward free radicals . in this work , five new n
- tert - butyl - substituted pbns were synthesized
along with a series of mono- ,
di- , and trihydroxymethyl n - tert - butyl - substituted derivatives . the water solubility , lipophilicity ,
and electrochemical properties were determined .
a uv vis stopped - flow
competitive technique was employed to determine the relative rate
constants of reaction with o2 .
the relative rate constants of phenyl adduct formation were experimentally
determined by an epr competition kinetic technique . using a computational
approach ,
the effect of the n - tert - butyl substituents on the nitronyl atom charge density and electron
density localization as well as on the free energies of nitrone reactivity
with o2 and ho2 were calculated .
finally , the cytoprotective properties
of selected compounds against oxidant - induced cell death were investigated .
all of the mono- , di- , and trisubstituted nitrones
with the substituents
in -positions ( see figure 1 for details )
were synthesized by a one - pot reduction / condensation of nitro derivatives
onto the commercially available benzaldehyde , as shown in scheme 1 .
pbn - ch2oh was synthesized from 2-methyl-2-nitro-1-propanol and benzaldehyde
in the presence of zinc powder and acoh in ethanol according to our
recently described procedure .
after purification
by flash chromatography and two successive crystallizations from etoac / n - hexane , nitrone 1 was obtained in 65% yield ,
which is slightly higher than that for the procedure used by janzen
and zawalsky ( 55% ) .
acetylation of nitrone 1 by a 1/1 v / v mixture of ac2o and pyridine led
to compound 2 ( also called pbn - ch2oac ) in
98% yield , after purification by flash chromatography .
first , 2-methyl-2-nitro-1-propanol
was activated using 1,1-carbonyldiimidazole ( cdi ) in the presence
of 4-dimethylaminopyridine ( dmap ) in thf , and then methylamine was
added to the reaction mixture to give compound 3 after
purification in 98% yield . in parallel , 2-methyl-2-nitropropanamine
( 4 ) was obtained from 2-methyl-2-nitro-1-propanol in
three steps and was then acetylated to
give the nitro compound 5 in 94% yield .
the one - pot reduction / condensation
of compounds 3 and 5 to benzaldehyde after
purification by flash chromatography and two successive crystallization
from etoac / n - hexane led to nitrones 6 ( also called pbn - ch2oconhme ) and 7 ( also
called pbn - ch2nhac ) in 70% and 68% yields , respectively . reagents and conditions : ( a )
benzaldehyde , zinc powder , acoh , 4 molecular sieves ; ethanol ,
15 60 c , 10 h ; ( b ) ac2o / pyr ( 1/1 v / v ) , room
temperature , 12 h ; ( c ) dci , dmap , thf , 2 h , room temperature , then
ch3nh2 , 18 h , room temperature . following the same synthetic procedure , pbn-(ch2oh)2 (
8) was also synthesized from 2-methyl-2-nitro-1,3-propanediol
in 65% yield , which corresponds to a significant improvement in comparison
to the procedure used by janzen and zawalsky with 15% yield .
finally , pbn-(ch2oac)2 ( 10 ) and pbn-(ch2oac)3 ( 11 ) were obtained by acetylation of nitrones 8 and 9 , respectively .
nitrones 1 , 7 , and 8 are soluble in water
up to a concentration of 200 g / l , after which the solution
became viscous but remained transparent .
this is significantly higher
than the solubility limit of pbn , which was found to be 21
when the amide and carbamate derivatives 7 and 6 are compared , a significant difference was noted , with 6 exhibiting a water solubility limit of 11 g / l .
we also demonstrated that the solubility of hydroxylated
compounds did not linearly correlate with the number of hydroxyl groups .
whereas the mono- and disubstituted hydroxyl compounds are highly
soluble in water ( > 200
g / l ) , the trisubstituted compound reaches
its
solubility limit at 21 g / l , likely due to intramolecular hydrogen
bonding between the three hydroxyl groups as previously observed . due to the oily form of the three ester derivatives ,
the relative lipophilicity
( log kw ) of the nitrones was measured
by hplc , and values are reported in table 1 .
this confirms the higher lipophilic character of the three ester
compounds in comparison to that of pbn with log kw values of 1.89 , 1.95 , and 2.17 for compounds 2 , 10 , and 11 , respectively , whereas
a value of 1.64 was found for pbn .
although compounds 6 and 7 exhibit different water solubilities , they were
both found to have similar lipophilicities , slightly lower than that
of pbn .
finally , the hydroxylated derivatives 1 , 8 , and 9 were found to be the least lipophilic
derivatives , where the lipophilicity correlates with the number of
hydroxyl groups : that is , the lower the number of hydroxyl groups ,
the higher the lipophilicity .
calculated partition coefficients ( c log p ) were also determined using marvin
software . except for the three ester derivatives , a good correlation
between log kw and c
partition coefficient values obtained
by hplc . calculated octanol / water
partition
coefficient values obtained using marvin software ( http://www.chemaxon.com/marvin/help/index.html ) . containing 50 mm of
nacl . containing 50 mm of
tbap . to evaluate the spin trapping ability
of the pbn - substituted derivatives , we investigated the formation
of various oxygen - centered radical spin adducts : i.e. , ho , o2 , and meo adducts . the hyperfine coupling constants ( hfccs ) of the monosubstituted
derivatives 1 , 2 , 6 , and 7 and those of the di- and trihydroxylated derivatives 8 and 9 are reported in table 2 . in most cases ,
the nitrones tested gave rise to a standard
six - line epr spectrum whose values are in agreement with those in
the literature .
two different conditions
were used to generate the superoxide adducts : that is , pyridine / h2o2 and dmso / ko2 . in the pyridine / h2o2 system ,
one predominant radical adduct was detected
in most cases with hfcc values in agreement with a o2 adduct . in the ko2 system ,
the
hyperfine coupling constants suggest o2 adduct formation with values higher than those in the pyridine / h2o2 system , which is likely due to solvent effects ,
as previously observed for para - substituted nitrones . for the hydroxylated derivatives , the presence of a second
nitroxide having a six - line pattern spectrum
this
second species corresponds to an oxazolidine - n - oxyl
compound coming from a cyclization reaction between one hydroxyl group
and the nitronyl carbon . under fenton conditions ,
the ratio of the cyclic species increased
with the number of hydroxyl groups : 1:3 for compound 1 ( an = 15.9 , ah = 20.1 ) and 2:3 for compound 8 ( an = 15.6 , ah = 19.9 ) ,
while for compound 9 bearing three hydroxyl groups ( an = 15.3 , ah = 19.7 ) ,
the cyclic species was predominant ( > 90% ) .
this suggests that cyclization
may be favored with an increasing number of hydroxyl groups , and a
thorough investigation on this is currently in progress in our laboratories .
the formation of five - membered cyclic nitroxides was also evident
in the ko2 system for the hydroxylated derivatives ; however ,
in this case , the ratio of the cyclic nitroxide decreased with the
number of hydroxyl groups .
cyclization was observed during methoxy
radical trapping for the monohydroxylated compound but not for the
di- and trihydroxylated derivatives .
regardless of the radical generating
system used , no evidence of cyclization was found for the carbamate-
and ester - based compounds , while for the amide derivative , cyclization
was only evident in the ko2 system .
the phenyl radical spin adduct was obtained by photolysis of a phenyl
iodide solution in benzene in the presence of the nitrones .
although
all the nitrones tested trapped ph , giving rise
to a standard six - line epr spectrum , it should be noted that a weak
signal was obtained with the trihydroxylated compound 9 . in all cases , an and ah values determined are in agreement with an aryl radical
adduct of a pbn - type nitrone .
the oxidative and reductive character
of these nitrones was investigated using cyclic voltammetry , and values
are reported in table 1 .
as already observed
for other nitrones , the oxidation of the nitronyl group was not detected . in contrast
, we observed that all of the nitrones exhibited an irreversible
one - step reduction , as shown in figure s2s4 ( supporting information ) .
the cathodic peak potential of the
-substituted derivatives is observed between 1.67 and
1.75 v vs ag / agcl , and that of the pbn is at 1.70
v. this is consistent with the findings by zuman and exner , who reported the weak influence of n - alkyl substituents on the reduction potential of -phenyl - n - alkyl nitrones , which was further confirmed by mcintire
et al .
we next studied the electrochemical
properties of the nitrones in acetonitrile containing tetrabutylammonium
perchlorate ( tbap ) as electrolyte .
previous works showed that pbn
undergoes an irreversible one - electron oxidation and a one - step , two - electron
reduction . in comparison to the case for the aqueous conditions , oxidation
of nitrones
was clearly observed in acetonitrile , as shown in figure 2 and figures s5 and s6 ( supporting
information ) , with values ranging from 1.44 to 1.83 v. for
the monosubstituted derivatives , the highest observed oxidation potential
was for the carbamate derivative 6 followed by the ester 2 and then by the hydroxylated 1 , which suggests
a strong inductive effect of the carbamate bond , making nitrone 6 harder to oxidize than nitrones 2 and 1 .
this shows that the presence of -substituents affects
the oxidation of the nitronyl function .
the amide compound 7 , with the lowest anodic peak potential in the series , is therefore
the easiest to oxidize , demonstrating that the oxidation of the nitronyl
group is more difficult in the presence of electron - withdrawing substituents ,
in agreement with the literature . with regard
to the number of substituents , the oxidation potential of the ester
derivatives 2 , 10 , and 11 increases
with the number of substituents , suggesting that the electronic effects
are additive .
no significant trend was observed for the mono- , di- ,
and trihydroxylated derivatives , whose potentials were close to that
of pbn , in agreement with the literature .
cyclic
voltammograms of pbn and compounds 2 , 6 ,
and 7 in acetonitrile containing 50 mm of
tbap with a sweep rate of 0.1 v s. the reduction of nitrones in a nonaqueous medium
was then investigated
and exhibited two reduction potentials for all of the -substituted
derivatives , whereas for pbn , only one reduction peak was observed
( figure 2 and figures s7 and s8 ( supporting information ) ) .
the presence of two
reduction potentials had been observed for -phosphorylated
nitrone spin traps . for the monosubstituted
derivatives , only a modest ease of reduction
the
reduction of the ester derivatives becomes slightly easier with increasing
numbers of substituents , suggesting an additive effect , as also observed
for the oxidation , which is in contrast to the hydroxylated derivatives ,
where no correlation was found .
we further studied the influence of
the sweep rate of pbn and compounds 2 and 7 on the anodic and cathodic peak current densities .
the linear relationship
between the cathodic and anodic peak currents and the square root
of the sweep rate , as shown in figures s9s11 ( supporting information ) , demonstrates that the
process is diffusion - controlled .
the diffusion
coefficients of the three nitrones were found to be in the same range
for both oxidation and reduction .
the reduction of nitrones 2 and 7 exhibited two separate reduction potentials
where the current intensity and the square scan speed were linear
for both peaks .
examination of the optimized structures
at the b3lyp/6 - 31 g * level
of theory shows c = n and n o bond distances that are
in the ranges of 1.3121.317 and 1.2761.292 ,
respectively , which are consistent with the x - ray crystallographic
c = n and n o bond lengths observed for n - tert - butyl--(2-pyridyl ) nitrone of 1.307
and 1.294 , respectively .
the natural
population analysis ( npa ) charges on the nitronyl carbon , nitronyl
nitrogen , and nitronyl oxygen atoms were determined at the pcm / b3lyp/6 - 31+g * *
level for compounds 13 and 511 as well as for the other n - tert - butyl - substituted derivatives ( table
s1 , supporting information ) . in general ,
increasing the number of substituents results in more positive charge
densities on the nitronyl c with the exception of a few compounds
such as pbn - nhc(=o)me and pbn - ch2p(=o)(ome)2 , whereas for the nitronyl n , an opposite but less pronounced
trend was observed . as for the nitronyl o ,
no significant effect of
the substitution was observed throughout the series of n - tert - butyl - substituted derivatives .
this observation
is consistent with increased distribution of the mesomeric b form
to the resonance hybrid form in the presence of multiple substituents ,
where there is an increased electron density on the nitronyl n and
a decreased electron density on the nitronyl c. this is further supported
by natural bond orbital ( nbo ) analysis , showing that there is a decrease
in the percent ( 0.252.97% ) of electron localization on the
nitronyl c with increasing substitution ( from mono to tri ) except
for pbn - nhc(o)me and pbn - ch2p(=o)(ome)2 , where there is an increase in electron distribution ( table s2 , supporting information ) .
the effect of the nature of the substituent on the
charge density of the nitrone moiety was also studied using h and c nmr spectroscopy .
similar to the case for carbonyl
compounds , nitrones are susceptible to nucleophilic addition reactions ,
and therefore , the electronic nature of the nitronyl c can affect
its reactivity toward nucleophilic radicals such as o2 .
figure 3a shows a
good correlation between the c nmr chemical shift in
cdcl3 of the nitronyl c and the calculated nitronyl
c charge
density , where there is a downfield shift with increasing positive
charge of the nitronyl c. this confirms the presence of a polar effect
from the substituent in a -position on the nitronyl charge
density and suggests a stabilization of the mesomeric b form due to
the electron - withdrawing effect of the substituents .
only the mono-
and dihydroxylated derivatives 1 and 8 were
out of the range likely due to the formation of intramolecular hydrogen
bonds between the hydroxyl group and the nitronyl o , which may induce a downfield shift .
an opposite trend was
observed for the h nmr chemical shift in cdcl3 of the nitronyl h , where an upfield shift of the -hydrogen
was observed with increased positivity of the nitronyl - c , further
confirming the polar effect from the n - tert - butyl substituents ( figure s12 ) .
correlation
of the nitronyl carbon charge densities with ( a ) nitronyl
c chemical shifts of nitrones 2 , 6 , 7 , 10 , 11 , and pbn ( r = 0.965 ) , excluding nitrones 1 and 8 ( marked as ) and 9 ( which is not soluble
in cdcl3 ) , ( b ) experimental relative rate constants of
o2 addition to nitrones ( ksn / kpr ) , including para - substituted nitrones ( marked as ) from
durand et al .
( r = 0.451 ) and excluding nitrone 2 ( marked as
) , and ( c ) experimental relative rate constants of phenyl
addition to nitrones ( kpn / ktn ) ( r = 0.504 ) .
we then applied
the uv vis stopped - flow technique for the determination of
the rate constant of the o2 reaction
to nitrones .
phenol red was used as a probe to measure o2 production , and the rate of formation
of this new species at 575 nm is directly proportional to the kinetics
of o2 decay .
the slope of the linear line generated from the uv vis absorption
plot was used to calculate the rate of nitrone spin trapping by using
eq 1 , where n is the pbn derivative and v and v are the initial rates of o2 addition to phenol red ( pr ) in
the absence and presence of pbn derivatives , respectively.1 the slopes of the
ko2 controls
were averaged to give kpr .
the relative
rate constants ( ksn / kpr ) are shown in table 3 , and for comparison , the rates of formation of dmpo and pbn are
included .
all of the relative rates were significantly lower than
1 , demonstrating that o2 reacts
more quickly with phenol red than with the nitrone spin traps . from
these values ,
the ksn / kspbn ratio was calculated ,
leading to the following order of increased reactivity to o2 : pbn-(ch2oh)2 <
pbn - ch2nhac < pbn-(ch2oh)3 <
pbn - ch2oh < dmpo < pbn - ch2oconhme <
pbn - ch2oac .
it is worth mentioning that all substituted
nitrones exhibit 1050 times higher rates of trapping
in comparison to pbn .
as shown in figure 3b ,
the plot of the rate constant of the o2nitrone reaction with the nitronyl - c charge density shows
increased rates of reaction for the more positively charged carbons ,
however , with a fairly poor correlation coefficient . for the sake
of comparison
the correlation for para - substituted nitrones
is even weaker , which caused us to conclude in our previous work that
o2 addition to nitrone might
be weakly electrophilic . with more compounds included in this study ,
the trend may suggest a nucleophilic nature of o2 addition to this set of nitrones , although the correlation is not
satisfactory .
this may also suggest that the reaction of o2 to nitrone is not charge - controlled but
rather orbital - controlled and , hence , warrants further investigation .
ratio of the second - order
rate constants
for the superoxide radical reaction with various nitrones ( ksn ) and with pbn ( kspbn ) in dmf / ko2 .
ratio of the second - order rate constants
for the phenyl radical trapping by various nitrones ( kpn ) and by pbn ( kppbn ) in benzene .
the epr signal of the adduct 9-ph was too weak to allow
a reliable determination of the
ratio .
since some nitrones in the series
were poorly water soluble or were found to be highly reactive toward
ho , the use of a fenton system was precluded .
therefore ,
we chose to study phenyl radical ( ph ) trapping
in benzene , where the corresponding adducts show high stability .
1,3,5-tris[(n-(1-diethylphosphono)-1-methylethyl)-n - oxyaldimine]benzene ( tn ) was used as
a competitive scavenger to examine the relative rates of trapping
by the nitrones 1 , 2 , and 611 in comparison to pbn ( figure 4 ) .
it is worth noting that the adduct decay must be slow enough
to be neglected to obtain reliable results with this approach .
the ph was generated by uv
photolysis of a solution containing a large excess of iodobenzene
in the presence of tn and of the nitrone of interest , denoted as n.
as previously observed , the possibility
of multiple trapping by tn was neglected , since the polyadducts were
never observed by epr in our study . in this method ,
the ph spin trapping rate was monitored by measuring the intensities ( as
the signal area ) of the epr signals of the corresponding adducts .
the standard kinetic competition model employed as described elsewhere yielded eq 2 . in this
equation ,
n and tn are denoted as kpn and ktn , respectively , while r and r represent
the trapping rate by tn only in the presence of n and by both tn and
n , respectively.2by plotting the r / r ratio as a function of the [ n]/[n ]
ratio for each nitrone 1 , 2 , and 611 , a straight line was obtained with a slope
equal to kpn / ktn .
five
experiments were performed at five different [ n]/[tn ] ratios kept
between 1 and 4 .
the commercially available pbn was then employed
instead of n in order to determine the kppbn / ktn ratio . from these
results ,
the kpn / kppbn ratio was calculated and
the values obtained for nitrones 1 , 2 , and 611 are reported in table 3 .
epr signals recorded in benzene by photolysis of 3 mol l phenyl iodide solution in the presence of the nitrones 10 and 7 at two different ratios /[tn ] :
( a ) /[tn ] = 0.67 ( = 20 mmol l and [ tn ] = 30 mmol l ) ; ( b ) /[tn ] = 2 ( = 40 mmol l and [ tn ] = 20 mmol l ) .
the peaks marked with
correspond to the phenyl radical adduct of 10 ,
while the other lines correspond to the phenyl radical adduct of tn .
though all the nitrones studied
were found to be less efficient
than the tris(phosphorylated nitrone ) tn , many of the substituted
pbns trapped ph significantly faster than pbn itself ,
where only the hydroxylated compounds exhibited trapping rates slower
than that of pbn .
it should be mentioned that the epr signal of the
phenyl radical adduct on 9 was much too weak to permit
a reliable evaluation of kpn / ktn .
this could be due to a much
lower trapping efficiency of 9 and/or to a more rapid
decay of the spin adduct . actually , it turned out that the ph adducts of the hydroxylated nitrones exhibited faster
decay than those of other nitrones , and this was more particularly
evident in the case of 9 .
this observation suggests that
the hydroxyl groups would intervene in the nitroxide decay mechanism .
the most efficient compounds in the series for trapping ph are the di- and triacetylated nitrones 10 and 11 and the amide derivative 7 , while the least
effective were pbn and the di- and monohydroxylated nitrones 8 and 1 .
similar to what was observed for the
stopped - flow kinetics experiments , the rates of reaction correlate
with the nitronyl - c charge density , where reasonable correlation can
be observed with ph ( figure 3c )
. the increased rate of trapping by -substituted nitrones
with increasing positive nitronyl - c charge density suggests a nucleophilic
nature of the ph addition to the nitronyl carbon
atom .
it has been shown that an electron - withdrawing substituent on
the aromatic ring of pbn - type compounds increases the reactivity of
the nitronyl group for nucleophilic addition reactions and nucleophilic
radical addition .
in contrast , pbn - type nitrones
bearing an electron - donating substituent have also been suggested
to exhibit high reactivity to electrophilic radicals . in this work
the polar effect of the n - tert - butyl substituents is obviously electron - withdrawing
with hydroxyl , ester , amide , and carbamate groups , which therefore
may favor nucleophilic addition .
this is in agreement with the findings
by sueishi et al . , who suggested the nucleophilic nature of phenyl
radical addition to nitrones .
more recently
de vleeshouwer et al . confirmed the moderate nucleophilic character
of the phenyl radical using natural population analysis .
examination of the
optimized structures at the b3lyp/6 - 31g(d ) level of theory of various
spin adducts show cnitronyl n and n o bond
distances of 1.2801.292 and 1.4721.513 , respectively ,
consistent with the x - ray crystallographic cnitronyl
n
and n o bonds observed for the phenyl radical adduct of n - tert - butyl--(2-pyridyl ) nitrone
with bond distances of 1.2871.291 and 1.4621.466 ,
respectively .
table 4 shows the energetics of o2 and ho2 addition to various mono- ,
di- , and tri-- and mono- , di- , and tri--substituted
pbn derivatives .
the majority of the nitrones ( 22 out of 35 ) exhibited
decreased reactivity of o2 and
ho2 as the number of substituents increase
from mono- to trisubstitution ( table 4 ) . only
in a few cases
did the favorability of radical addition significantly
increase with increasing substitution ( i.e. , from mono- to trisubstitution ) ,
such as in the addition of o2 to cooh , nhc(=o)me , ch2oc(=o)me , and ch2sme and of ho2 to cooh , nhc(=o)me , and
ch2c(=o)nh2 .
the reactivities
of o2 in general are endoergic
with nhc(=o)me mono- , di- , and trisubstitution being
the most favorable with grxn(298
k ) ( kcal / mol ) values of 12.7 , 11.9 and 6.9 , respectively .
the structures
of these o2 adducts show intramolecular
h - bonding interactions between the amide h and peroxyl o ( figure 5 ) , resulting in proton abstraction of one of the
amide h s by the peroxide o to form the hydroperoxyl moiety ,
similar to that observed for 5-carbamoyl-5-methyl-1-pyrrroline n - oxide ( ampo ) with an endoergic
grxn(298 k ) value of 6.1 kcal / mol
and for diamide - substituted dmpo derivatives with grxn(298 k ) = 3.3 kcal / mol , both of which became
the basis for the fast and favorable reactivity of amide - conjugated
nitrones in comparison to other spin traps with no such strong intramolecular
interactions .
the reactivity of ho2 with nitrones that are monosubstituted with ch2oc(=o)me and disubstituted with och(=o)me
gave the most exoergic free energies of reaction with grxn(298 k ) ( kcal / mol ) of 4.4 and 3.5 ,
respectively .
the most exoergic grxn(298 k ) ( kcal / mol ) value observed among all the trisubstituted
analogues was only 1.0 for the ome trisubstitution .
previously , at the same level of theory , we showed that addition of
ho2 to the monoester - substituted empo
and the diester - substituted depo gave the most exoergic grxn(298 k ) value of 6.2 kcal / mol in
comparison to other dmpo derivatives .
optimized o2 adduct structures
with the least endoergic free energies of formation , showing the intramolecular
h - bond interaction of the amide h with the peroxyl o. the absence of a significant global trend in ho2/o2 reactivity
as a function of increasing nitronyl - c charge density and/or increasing
substitution could be accounted for by the competing inductive effects
of the methyl group in the partially - and -substituted
pbn as well as the competing resonance effects of the phenyl ring
with the inductive effects of the - and -substitution .
for mono--substituted pbn ( with the exception of two outliers ,
p(=o)(ome)2 and nh(c = o)me ) ,
a fairly poor correlation ( r = 0.66 )
can be observed between the charge densities on the nitronyl c with
their respective free energies ( grxn(298 k ) ) of addition with o2 ( figure s12 , supporting information ) .
in a similar study involving para substitution on pbn
, we showed that
there was no correlation that can be observed for grxn(298 k ) and nitronyl carbon charge densities in both
o2 and ho2 addition reactions .
therefore , the
reactivity of o2 and ho2 with mono--substituted pbn might
be similar in nature ( i.e. , nucleophilic ) to those observed for the
o2 addition to 5-substituted
dmpo analogues which are also mono--substituted , but the effect is much less pronounced , indicating
that inductive effect of the substituents for pbn is weaker than that
of dmpo analogues .
for the mono--substitution , no correlation
could be observed with the charge density and their respective grxn(298 k ) values of reactivity with o2 ( figure s12 ) , which could be due to the presence of the methylene group that
can further diminish the inductive effect by the functional substituent
groups .
cytoprotective properties
of nitrones against h2o2-induced cell death
was investigated in vitro using bovine aortic endothelial cells ( baec ) .
baec were preincubated with varying concentrations ( 1050 m )
of nitrone derivatives 1 , 2 , and 68 ( i.e. , pbn - ch2oh , pbn - ch2oac , pbn - ch2oconhme , pbn - ch2nhac , and pbn-(ch2oh)2 ) and were challenged for 2 h with h2o2 ( 1 mm ) .
extent of cytoprotection was measured using
[ 3-(4,5-dimethylthiazol-2-yl)-25-diphenyltetrazolium - bromide ]
( mtt ) assay .
our results are presented in figure 6 and show that at 10 m nitrones 2 and 7 exhibited the highest cytoprotection against h2o2-induced toxicity . at 50 m ,
the protection afforded
by the nitrones was more pronounced for pbn and compounds 1 , 7 and 8 while for compounds 2 the protection remained similar .
a significant decrease of cell
viability for compound 6 was noted which was even lower
than that of the control and may indicate a slight toxicity due to
the carbamate substituent .
cytoprotectivity of pbn derivatives at 10 and
50 m on bovine
aortic endothelial cells against 1 mm h2o2 after
2 h of incubation . to examine the relationship
between the electrochemical properties
and the antioxidant activities of our derivatives
, we tried to correlate
the cytoprotection data versus the electrochemical potentials of the
nitrones .
while no correlation between the reduction potential and
the cell viability of nitrone - treated baec was observed , a good correlation
was observed for the oxidation potentials recorded in acetonitrile
with the following order of increasing protective property : pbn - ch2oconhme < pbn - ch2oac < pbn - ch2oh pbn-(ch2oh)2 < pbn < pbn - ch2nhac . whereas this correlation is particularly obvious at
50 m , where increased cytoprotection is inversely correlated
with the oxidation potential ( figure 7 ) , at
10
it has to
be noted that , at 10 m , the protection afforded by the nitrones
against 1 mm h2o2 was very limited .
this indicates
that the ability of nitrones to oxidize at lower potentials offers
better cytoprotection , further supporting the role of nitrones in
attenuating oxidant - mediated toxicity by an antioxidant mechanism
and not solely through spin trapping properties .
correlation of cell viability
with oxidation potential of nitrones 1 , 2 , 68 , and
pbn in acetonitrile ( r = 0.910 ) .
in
this work , we have studied the electronic effect of various
substituents on the reactivity of -phenyl - n - tert - butyl nitrones .
a series of n - tert - butyl - substituted monohydroxyl ( ch2oh ) , monoester ( ch2oac ) , monoamide ( ch2nhac ) ,
and monocarbamate ( ch2oconhme ) as well as di- and trihydroxyl
and di- and triester derivatives was prepared in good yield .
the substituent
effect on the redox properties was investigated by cyclic voltammetry
and showed that electron - withdrawing groups make the nitronyl group
more difficult to oxidize .
the substituent effect was also demonstrated
by a computational approach , where increased positivity on the nitronyl
carbons was observed for multiply - and -substituted
compounds , which correlates well with experimental nmr chemical shifts .
a uv vis stopped - flow kinetic technique was used to demonstrate
the nucleophilic nature of superoxide ( o2 ) addition to nitrone , in agreement with previous findings on cyclic
nitrones .
the thermodynamics of o2 adduct formation showed that the reactivity is endoergic in general ;
however , for -substituted derivatives , a modest correlation
was observed with the nitronyl charge density , suggesting a weak nucleophilic
nature of o2 addition .
moreover ,
the nucleophilic nature of phenyl radical ( ph )
addition to nitrone was also observed using an epr kinetic method .
finally , a correlation between the cytoprotective property of nitrones
against h2o2-induced cell death and their oxidation
potential was observed , indicating that the antioxidant properties
are also affected by the nature of the substituent .
this study confirms
that the electronic effect of the substituents grafted on the n - tert - butyl group is of high importance
in the design of nitrones with improved trapping and antioxidant properties .
among the nitrones tested ,
the amide derivative pbn - ch2nhac gave the best properties , such as low oxidation potential , good
trapping properties , and cytoprotective activity , making the amide
bond an efficient linker for n - tert - butyl functionalization of the -phenyl n - tert - butyl nitrone .
tlc analysis was performed on aluminum sheets
coated with silica gel ( 4063 m ) .
compound detection
was achieved either by exposure to uv light ( 254 nm ) or by spraying
a 5% sulfuric acid solution in ethanol or a 2% ninhydrin solution
in ethanol and then heating to 150 c .
uv / vis spectra were recorded on a uv / vis spectrometer equipped with
a double - compartment quartz cell of 10 mm length .
the h nmr spectra were recorded at
250 or 400 mhz and the c nmr at 62.86 or 100 mhz .
chemical
shifts are given in ppm relative to the solvent residual peak as a
heteronuclear reference for h and c. abbreviations
used for signal patterns are as follows : bs , broad singlet ; s , singlet ;
d , doublet ; dd , doublet of doublets ; t , triplet ; q , quartet ; m , multiplet .
hr - ms spectra were recorded on a mass spectrometer equipped with a
tof analyzer for esi+ experiments . under an argon atmosphere and with
stirring , benzaldehyde ( 0.80 g , 7.54 mmol ) , 2-methyl-2-nitro-1-propanol
( 1.8 g , 15.1 10 mol ) , and acoh ( 2.5 ml ,
45.08 mmol ) were dissolved in etoh .
the mixture was cooled to 0 c ,
and then zinc powder ( 1.92 g , 29.6 mmol ) was slowly added in order
to keep the temperature below 15 c .
the mixture was stirred
at room temperature for a couple of minutes and then heated to 60
c in the dark for 10 h in the presence of molecular sieves ( 4
) .
the reaction mixture was filtered off through a pad of celite ,
and the solvent was removed under vacuum .
the crude mixture was purified
by flash chromatography ( etoac / cyclohexane 6/4 v / v ) followed by two
successive crystallizations from etoac / n - hexane to
give compound 3 ( 0.94 g , 4.87 mmol , 65% ) as a white powder : rf = 0.42 ( etoac / cyclohexane 8/2 v / v ) ; mp 78.578.9
c ; h nmr ( cdcl3 , 400 mhz ) 8.27
( 2h , m ) , 7.48 ( 1h , s ) , 7.43 ( 3h , m ) , 4.244.27 ( 1h , t , j = 6.2 hz ) , 3.793.80 ( 2h , d , j = 6.0 hz ) , 1.61 ( 6h , s ) ; c nmr ( cdcl3 , 100
mhz ) 132.1 , 130.7 ( ch ) , 130.3 ( c ) , 129.2 ( ch ) , 128.5 , 72.9
( c ) , 70.0 ( ch2 ) , 23.9 ( ch3 ) ; uv ( meoh ) max 296 nm ; hr - ms ( esi+ , m / z ) calcd for c11h15no2 [ ( m + h ) ] 194.1181 , found 194.1180 .
the spectral data of compound 3 were in agreement with those reported by janzen et al . ,
except for the melting point , which was found to be 7576 c .
with stirring , compound 1 ( 0.35 g , 1.81 mmol ) was dissolved in a ac2o / pyridine
( 1/1 v / v ) mixture at 0 c .
after 12 h of stirring at room temperature ,
the mixture was poured into cold 1 n hcl and extracted with ch2cl2 ( 3 ) .
the organic layer was washed with
brine , dried over na2so4 , and concentrated under
vacuum .
the crude mixture was purified by flash chromatography ( cyclohexane / etoac
6/4 v / v ) to give compound 2 ( 0.42 g , 1.79 mmol , 98% )
as a white oil : rf = 0.38 ( etoac / cyclohexane
5/5 v / v ) ; h nmr ( cdcl3 , 400 mhz ) 8.30
( 2h , m ) , 7.50 ( 1h , s ) , 7.43 ( 3h , m ) , 4.43 ( 2h , s ) , 2.03 ( 3h , s ) , 1.62
( 6h , s ) ; c nmr ( cdcl3 , 100 mhz ) 170.5
( co ) , 130.7 ( c ) , 130.5 , 129.0 , 128.5 ( ch ) , 72.1 ( c ) , 68.3 ( ch2 ) , 23.7 , 20.8 ( ch3 ) ; uv ( meoh ) max 298 nm ; hr - ms ( esi+ , m / z ) calcd
for c13h17no3 [ ( m + h ) ] 236.1286 , found 236.1283 . under an argon atmosphere and with stirring in
a sealed tube , 2-methyl-2-nitro-1-propanol
( 1 g , 8.39 mmol ) , dci ( 2.11 g , 16.78 mmol ) , and dmap ( 0.102 g , 0.839
mmol )
after 2 h of
stirring at room temperature , methylamine ( 1.13 g , 16.78 mmol ) was
added and the stirring was continued for 18 h. then , the mixture was
filtered and the solvent was removed under vacuum .
the crude mixture
was purified by flash chromatography ( cyclohexane / etoac 9/1 v / v ) to
give compound 3 ( 1.45 g , 8.23 mmol , 98% ) as a white powder : rf = 0.30 ( cyclohexane / etoac 8/2 v / v ) ; mp 48.349.3
c ; h nmr ( cdcl3 , 250 mhz ) 4.76
( 1h , bs ) , 4.39 ( 2h , s ) , 2.78 ( 3h , d , j = 4.90 hz ) ,
1.59 ( 6h , s ) ; c nmr ( cdcl3 , 62.86 mhz )
156.0 ( co ) , 86.7 ( c ) , 68.7 ( ch2 ) , 27.6 , 23.0 ( ch3 ) .
hr - ms ( esi+ , m / z ) calcd for
c6h13n2o4 [ ( m + h ) ] 177.0875 , found 177.0878 .
2-methyl-2-nitropropanamine ( 3.70 g ,
31.50 mmol ) was used as the starting material .
the crude mixture was
purified by flash chromatography ( etoac / cyclohexane 8/2 v / v ) to give
compound 5 ( 4.7 g , 29.16 mmol , 94% ) as a white powder : rf = 0.48 ( etoac ) ; mp 102.6103.1 c ; h nmr ( cdcl3 , 250 mhz ) 6.15 ( 1h , bs ) , 3.71
( 2h , d , j = 6.6 hz ) , 2.00 ( 3h , s ) , 1.56 ( 6h , s ) ; c nmr ( cdcl3 , 62.86 mhz ) 170.7 ( co ) , 88.8
( c ) , 46.1 ( ch2 ) , 24.0 , 23.2 ( ch3 ) .
hr - ms ( esi+ , m / z ) calcd for c6h13n2o3 [ ( m + h ) ] 161.0926 , found
161.0927 .
benzaldehyde ( 0.30 g , 2.84
mmol ) and compound 3 ( 1 g , 5.67 mmol ) were used as starting
materials .
the crude mixture was purified by flash chromatography
( etoac / cyclohexane 5/5 v / v ) followed by two successive crystallizations
from etoac / n - hexane to give compound 6 ( 0.5 g , 2.0 mmol , 70% ) as a white powder : rf = 0.23 ( etoac / cyclohexane 7/3 v / v ) ; mp 127.8128.1
c ; h nmr ( cdcl3 , 400 mhz ) 8.30
( 2h , m ) , 7.48 ( 1h , s ) , 7.427.43 ( 3h , m ) , 4.66 ( 1h , m ) , 4.45
( 2h , s ) , 2.762.77 ( 3h , d , j = 4.9 hz ) , 1.60
( 6h , s ) ; c nmr ( cdcl3 , 100 mhz ) 156.6
( co ) , 131.4 ( ch ) , 130.7 ( c ) , 130.4 , 128.9 , 128.5 ( ch ) , 72.6 ( c ) , 68.5
( ch2 ) , 27.6 , 23.6 ( ch3 ) ; uv ( meoh ) max 298 nm ; hr - ms ( esi+ , m / z ) calcd for c13h18n2o3 [ ( m + h ) ] 251.1395 , found 251.1390 .
benzaldehyde ( 0.26 g , 2.45
mmol ) and compound 5 ( 0.8 g , 5.0 mmol ) were used as starting
materials .
the crude mixture was purified by flash chromatography
( etoac ) followed by two successive crystallizations from etoac / n - hexane to give compound 7 ( 0.39 g , 1.66 mmol ,
68% ) as a white powder : rf = 0.35 ( etoac / methanol
9.5/0.5 v / v ) ; mp 114.1114.6 c ; h nmr ( cdcl3 , 400 mhz ) 8.27 ( 2h , m ) , 7.50 ( 1h , s ) , 7.44 ( 3h , m ) ,
6.62 ( 1h , m ) , 3.683.70 ( 2h , d , j = 6.3 hz ) ,
1.98 ( 3h , s ) , 1.60 ( 6h , s ) ; c nmr ( cdcl3 ,
100 mhz ) 170.5 ( co ) , 131.7 , 130.7 ( ch ) , 130.4 ( c ) , 129.0 ,
128.6 ( ch ) , 73.4 ( c ) , 47.3 ( ch2 ) , 25.1 , 23.3 ( ch3 ) ; uv ( meoh ) max 298 nm ; hr - ms ( esi+ , m / z ) calcd for c13h18n2o2 [ ( m + h ) ] 235.1446 , found 235.1442 .
benzaldehyde ( 0.78 g , 7.40
mmol ) and 2-methyl-2-nitro-1,3-propanediol ( 2 g , 14.80 mmol ) were
used as starting materials .
the crude mixture was purified by flash
chromatography ( etoac ) followed by two successive crystallizations
from etoac / n - hexane to give compound 8 ( 0.99 g , 4.74 mmol , 65% ) as a white powder : rf = 0.21 ( etoac ) ; mp 84.285.6 c ; h nmr ( cdcl3 , 400 mhz ) 8.24 ( 2h , m ) , 7.52 ( 1h ,
s ) , 7.43 ( 3h , m ) , 3.913.98 ( 6h , m ) , 1.50 ( 3h , s ) ; c nmr ( cdcl3 , 100 mhz ) 134.7 , 131.1 ( ch ) , 129.9
( c ) , 129.6 , 128.6 ( ch ) , 75.9 ( c ) , 66.8 ( ch2 ) , 19.3 ( ch3 ) ; uv ( meoh ) max 296 nm ; hr - ms ( esi+ , m / z ) calcd for c11h15no3 [ ( m + h ) ] 210.1130 , found 210.1126 .
the
spectral data of compound 8 were in agreement with those
reported by janzen et al . , except for
the melting point , which was found to be 5255 c .
compound 8 ( 0.40 g , 1.79 mmol ) was used as the starting
material .
the crude mixture was purified by flash chromatography ( cyclohexane / etoac
4/6 v / v ) to give compound 10 ( 0.25 g , 0.85 mmol , 45% )
as a white oil : rf = 0.27 ( etoac / cyclohexane
6/4 v / v ) ; h nmr ( cdcl3 , 400 mhz ) 8.22
( 2h , m ) , 7.41 ( 1h , s ) , 7.36 ( 3h , m ) , 4.50 ( 2h , d , j = 11.7 hz ) , 4.35 ( 2h , d , j = 11.7 hz ) , 1.98 ( 6h , s ) , 1.59 ( 3h , s ) ; c nmr ( cdcl3 , 100 mhz ) 169.2 ( co ) , 131.9 ,
129.8 ( ch ) , 129.3 ( c ) , 128.1 , 127.5 ( ch ) , 72.9 ( c ) , 64.3 ( ch2 ) , 19.7 , 17.8 ( ch3 ) ; uv ( meoh ) max 298
nm ; hr - ms ( esi+ , m / z ) calcd for
c15h19no5 [ ( m + h ) ] 294.1341 ,
found 294.1337 .
-phenyl - n-(2-hydroxymethyl-1,3-dihydroxy-2-propyl )
nitrone ( 0.40 g , 1.77 mmol ) was used
as the starting material .
the crude mixture was purified by flash
chromatography ( cyclohexane / etoac 6/4 v / v ) to give compound 11 ( 0.43 g , 1.22 mmol , 69% ) as a white oil : rf = 0.42 ( etoac / cyclohexane 5/5 v / v ) ; h nmr
( cdcl3 , 400 mhz ) 8.28 ( 2h , m ) , 7.45 ( 3h , s ) , 7.34
( 1h , m ) , 4.61 ( 6h , s ) , 2.06 ( 9h , s ) ; c nmr ( cdcl3 , 100 mhz ) 169.9 ( co ) , 133.9 , 131.1 ( ch ) , 130.0 ( c ) ,
129.3 , 128.6 ( ch ) , 75.5 ( c ) , 61.4 ( ch2 ) , 20.6 ( ch3 ) ; uv ( meoh ) max 300 nm ; hr - ms ( esi+ , m / z ) calcd for c17h21no7 [ ( m + h ) ] 352.1396 , found 352.1388 . for pbn and nitrones 6 and 9 , a uv calibration curve at 290
nm was
established from solutions ranging from 10 to
10 g / l ( r > 0.995 ) .
a saturated solution of nitrone was prepared at 40 c and then
let stand at room temperature overnight .
after centrifugation ( 12000 g , 15 min ) at room temperature , the concentration of the
supernatant solution was determined using the calibration curve .
for
nitrones 1 , 7 , and 8 , weighed
amounts of the nitrone were placed in a vial containing water at room
temperature .
after each addition , the solution was carefully shaken
and the complete dissolution was checked by visual observation .
compounds were dissolved in meoh at 1.0 mg / ml and were injected
onto a c18 reverse phase column ( 250 mm 4.6 mm , 5 m ) .
the compounds were eluted at various meoh and water ratios ( 7/3 to
3/7 v / v ) using a flow rate of 0.8 ml / min .
the column temperature was
25 c , and the uv detector wavelength was 298 nm .
linear
regression analysis were performed on three data points for compound 9 ( from 5/5 to 3/7 ; r = 0.9996 ) ;
four points for compound 1 ( from 6/4 to 3/7 ; r = 0.9945 ) , compound 8 ( from 6/4
to 3/7 ; r = 0.9973 ) , compound 2 ( from 7/3 to 4/6 ; r = 0.9957 ) , compound 10 ( from 7/3 to 4/6 ; r = 0.9951 ) ,
compound 11 ( from 7/3 to 4/6 ; r = 0.9976 ) ; five points for compound 7 ( from
7/3 to 3/7 ; r = 0.9936 ) , and compound 6 ( from 7/3 to 3/7 ; r = 0.9944 ) .
the log k values were calculated by using
the equation : log k = log((t t0)/t0 ) , where t is the retention time of the nitrone
and t0 is the elution time of meoh , which
is not retained on the column .
the partition coefficient
octanol / water ( c log p ) was determined
using marvinsketch 5.9.0 , which is available
at www.chemaxon.com/marvin .
the electrochemical
experiments were carried out using a three - electrode cell under a
dry argon atmosphere at room temperature .
an ag / agcl / saturated nacl
electrode was used as the reference electrode and a platinum wire
as the auxiliary electrode . the working electrode ( glassy carbon )
was polished prior to each experiment using a 0.04 m aqueous
alumina slurry on a wetted polishing cloth .
the general instrument settings used
for spectral acquisition were as follows : microwave power , 10 mw ;
modulation amplitude , 2 g ; received gains , 9 10 to 9 10 ; scan time , 60 s ; sweep width , 99 , 147 ,
or 249 g. spectra were recorded at room temperature , and measurements
were performed using a 50 l quartz cell or capillary tube for
uv or non - uv irradiation experiments , respectively .
the spectrum simulation
was carried out using the winsim program , available as free software from public electron paramagnetic resonance
software tools ( http://www.niehs.nih.gov/research/resources/software/tox-pharm/tools/ ) . to generate the hydroxyl radical ,
nitrone ( 20 mm )
was dissolved in a fenton system containing hydrogen
peroxide ( 0.2% ) , edta ( 2 mm ) , and iron(ii ) sulfate ( 1 mm ) in phosphate
buffered saline solution .
the superoxide anion
radical was generated using different concentrations of nitrones ( 40
mm for compounds 2 and 6 , 80 mm for compound 10 , and 20 mm for other cases ) to a solution of dmso containing
a 20% saturated solution of ko2 in dmso .
a pyridine
solution of nitrone ( 20 mm ) containing 230 mm h2o2 was used .
the methoxy radical was generated
by adding 1 mg of solid pb(oac)4 to a dmso solution
of nitrone ( 25 mm ) containing 10% v / v of meoh .
the phenyl radical
was generated
by photolysis of a benzene solution of phenyl iodide ( 3 m ) , using
a xenon discharge lamp ( 250 w ) , giving near - uv and visible radiations
in the presence of nitrone ( 50 mm ) .
for the addition of each
radical species ( o2 or ho2 ) to substituted pbn derivatives , a density
functional theory computational approach was employed
to determine the optimized geometry , vibrational frequencies , and
single - point energies of all stationary points .
the effect of aqueous solvation was also investigated
using the polarizable continuum model ( pcm ) .
single - point
energies were obtained at the b3lyp/6 - 31+g * * level on the basis of the optimized b3lyp/6 - 31 g * geometries .
charge and spin densities were obtained from a natural population
( npa ) analysis , and percent electron
localizations were obtained from natural bond orbital ( nbo ) analysis at the single - point pcm / b3lyp/6 - 31+g**//b3lyp/6 - 31 g *
level .
stationary points for nitrones and their respective adducts have zero
imaginary vibrational frequency , as derived from a vibrational frequency
analysis ( b3lyp/6 - 31 g * ) . a scaling factor of 0.9806
was used for the
zero - point vibrational energy ( zpe ) corrections for the b3lyp/6 - 31 g *
level . here , thermal correction to gibbs
free energy was added to the total energy : that is , the sum of total
electronic ( 0 ) and thermal free ( gcorr ) energies with zpe correction ( as outputs from gaussian )
were used for g value estimation at the 6 - 31 g *
level with the solvent effect added at the 6 - 31+g * * level .
the g values of reactions were simply the difference of the
sums of these values for the reactants and the products .
spin contamination
for all of the stationary points of the radical structures was negligible :
i.e. , s = 0.75 . a procedure was followed similar
to that of villamena et al .
a solution
of ko2-saturated dmf was prepared by adding 200
mg of ko2 to 5 ml of dmf under a nitrogen atmosphere .
the supernatant ( 1
ml ) was further diluted with 10 ml of dmf to reach a maximum absorbance
of 3 at 575 nm when it was mixed with 500 m phenol
red in 90% dmf/10% h2o .
this solution was kept on ice and
under a nitrogen atmosphere and let stand for 10 min before stopped - flow
testing .
solutions of the nitrones and 500 m phenol red in
90% dmf/10% h2o were prepared .
a stopped - flow technique
consisted of 150 l of ko2 solution and 150 l
of nitrone solution , and the growth and decay of absorption was measured
using a uv vis spectrophotometer rapid mix accessory .
the plot
was exported to sigma plot 11.0 , and the absorption increase was fitted
to a linear equation ( y = ax + b ) . to ensure a constant concentration of ko2 throughout the experiment , a control of ko2 and 500 m
phenol red
each
nitrone was tested with four or more concentrations ranging from 5
to 200 mm .
the solvents
were of the highest
grade of purity commercially available and were used without further
purification .
phenyl radical was produced
directly in the epr spectrometer cavity by uv photolysis of a 3 mol
l iodobenzene solution in benzene .
the method
of kinetic competition permitted us to evaluate the ratio of the second - order
rate constants for the trapping of ph by one of
the nitrone n of interest ( kpn , corresponding to the compounds 1 , 2 , and 611 ) and tn ( ktn ) , used as competitive inhibitor .
then , the commercially
available pbn was also tested versus tn in order to determine the
ratio of the rate constants for the trapping of ph by pbn and by tn : i.e. , kppbn / ktn .
the concentrations of the various nitrones
were varied from 5 to 20 mmol l , with the [ n]/[tn ]
ratio kept between 1 and 4 . for each nitrone , five experiments were
repeated twice at [ n]/[tn ] values equal to 1 , 1.6 , 2 , 3.2 , and 4 .
in each case , a series of 30 epr spectra was then recorded ( scan time
for a single spectrum 15 s ) on a spectrometer operating at x - band
with 100 khz modulation frequency .
the signal - to - noise ratio was improved
using an svd procedure , as described elsewhere .
the signal recorded exactly 1.5 min after the beginning
of the reaction was then simulated using the winsim software in order
to determine the relative areas of the adducts n - ph and tn - ph . in
this approach ,
the ratio r / r was
evaluated as follows : bovine aortic endothelial
cells ( baecs ) were cultured in t-75 flasks , in dulbecco s modified
eagle medium ( dmem ) supplemented with 1 g / l glucose , 10% fetal bovine
serum , l - glutamine , 2.5 mg / l of endothelial cell growth supplement ,
1% of nonessential amino acids , and 1% of pen / strep at 37 c
under a humidified atmosphere of 5% co2 and 20% o2 .
cytoprotection
of -substituted nitrones against h2o2-induced toxicity was assessed via intracellular reduction of mtt
( 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide ) to
its insoluble formazan form .
a confluent baec culture was seeded onto
96-well plates ( 1.0 10 cells / well ) and
incubated for 24 h. beacs were pretreated with various nitrone concentrations
( 25 , 50 , and 100 m ) and incubated for 24 h. the cells were
then incubated in 1 mm hydrogen peroxide for 2 h , followed by the
addition of 100 l of phosphate buffered saline ( pbs ) and 50
l of mtt solution ( 5 mg / ml , 5% ethanol ) for 1 h. the cells
were then incubated in 200 l of dimethyl sulfoxide ( dmso ) for
2 h. formazan formation was measured using a microplate reader at
595 nm absorbance .
data were calculated as percent absorbance of untreated
cells sem ( n = 5 ) .
Output:
| in
this work , a series of -phenyl - n - tert - butyl nitrones bearing one , two , or three substituents
on the tert - butyl group was synthesized .
cyclic voltammetry
( cv ) was used to investigate their electrochemical properties and
showed a more pronounced substituent effect for oxidation than for
reduction .
rate constants of superoxide radical ( o2 ) reactions with nitrones were determined using
a uv vis stopped - flow method , and phenyl radical ( ph ) trapping rate constants were measured by epr spectroscopy .
the
effect of n - tert - butyl substitution
on the charge density and electron density localization of the nitronyl
carbon as well as on the free energies of nitrone reactivity with
o2 and ho2 were computationally rationalized at the pcm / b3lyp/6 - 31+g**//b3lyp/6 - 31 g *
level of theory .
theoretical and experimental data showed that the
rates of the reaction correlate with the nitronyl carbon charge density ,
suggesting a nucleophilic nature of o2 and ph addition to the nitronyl carbon atom .
finally , the substituent effect was investigated in cell cultures
exposed to hydrogen peroxide and a correlation between the cell viability
and the oxidation potential of the nitrones was observed . through
a combination of computational methodologies and experimental methods ,
new insights into the reactivity of free radicals with nitrone derivatives
have been proposed . |
PubmedSumm118691 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: small - angle light scattering ( sals )
techniques offer a number of advantages for the investigation of the nature and
behavior of polymer materials .
nonintrusive characterization of the
flow field of transparent film
is an essential step toward an implementation of a structural control system
that can regulate the structure development during processing .
a combination of in situ
birefringence and depolarized light - scattering experiments was used to study
the formation of an ordered cylindrical microstructure in a
polystyrene - block - polyisoprene copolymer melt under a shear flow field .
a new multivariable measurement
approach for
characterizing and correlating the nanoscale and microscale morphology of
crystal - amorphous polymer blends with melt - phase behavior is described .
a
vertical small - angle light scattering
instrument optimized for examining the scattering and light transmitted
from structures ranging from 0.5 to 50 m , thereby spanning the size range
characteristic of the initial - to - late stages of thermal - phase transitions
( e.g. , melt - phase separation and crystallization ) in crystal - amorphous polymer
blends , was constructed .
the present paper explores an
effective means of characterizing structural changes of
poly(vinyl chloride ) ( pvc ) particles during gelation and fusion of pvc
plastisols with small - angle light scattering .
the sals method was shown to
provide an in situ observation of swelling of pvc particles as well as
quantitative information of average size of swollen particles while they are in
progress of gelation and fusion .
in addition , the sals method enabled one to
evaluate the relative solvent power of plasticizers from the manner of increase
in the correlation distances .
recently , there has been increasing interest in understanding
the complex processes that take place during the processing of polymer blends [ 46 ] . for this purpose ,
the small - angle
light scattering technique is a very efficient method [ 79 ] .
one of the important
characteristics of light scattering is that it is a nondestructive test .
this makes
it possible to
follow the time evolution of the phase separation process .
the scattering pattern
is a direct reflection of
orientation , shape , and size of the structure .
another advantage is that with
an appropriate choice of instruments , one can follow extremely fast events having
a low optical contrast [ 10 , 11 ] . for optimum mechanical and optical
properties , fine - structured
morphologies on a submicron scale
are generally desired , as fine dispersions or
cocontinuous morphologies with a low volume fraction of one component .
the light
scattering method is valid for giving information about overall structures but
is difficult to use for extracting local information on morphology .
recently , a
digital image processing technique has shown its utility in analyzing the
pattern formation in polymer systems .
various light scattering and optical techniques have been investigated as potential candidates for characterization of
multiphase polymeric materials .
sals is one of the tools that can be used to
study a phase separation .
it is shown that sals can be used to discriminate
between nucleation and growth ( ng ) and spinodal decomposition ( sd ) even when
both give a pattern composed of a ring . the gelation mode as a function of
time
was analyzed
for polymers and polymer - carbon fiber composites by using polarized microscopy
and polarized light scattering in terms of the formation of polymer spherulites .
endoh et al . aimed at elucidating the influence of shear - induced
structures ( shear - enhanced concentration fluctuations and/or shear - induced
phase separation ) , as observed by rheo - optical methods with small - angle light
scattering under shear flow ( shear - sals ) and shear - microscopy , on viscoelastic
properties in semidilute polystyrene ( ps ) solutions of 6.0 wt% concentration
using dioctyl phthalate ( dop ) as a solvent and tricresyl phosphate ( tcp ) as a
good solvent .
small - angle
light scattering was used to determine the binary interaction parameter in a
molten blend of linear polyethylene ( lpe ) ( mw = 52 kg / mol , pdi = 2.9 ) and linear
low - density polyethylenes ( lldpes ) based on homogeneous ethylene-1-butene
copolymers ( lldpe-1 , 18.7 mol% butane branches , mw = 58.1 kg / mol , and lldpe-2 , 5.9 mol% butene branches , mw = 70 kg / mol ) .
our results
are significant because they show that the low optical contrast between
coexisting phases in polyolefin blends does not limit the determination of
phase boundaries by sals as was previously assumed .
the quantitative analysis software system can be integrated
into the picture archiving and communication system .
the combination of advances in charge - coupled - device
( ccd ) fabrication , camera design , digital interface technology , and software
development has enabled scientific imaging device manufacturers to overcome the
challenges created by the wide range of requirements . the software kits , which include
pci device driver and image processing package , are developed based on windows
os . in our study , the transparent film
is viewed through crossed polarizers to reveal the light scattering pattern .
a
high - speed ccd camera is used to record the sals signal in real time with different process conditions for
subsequent analysis .
an optical image real - time analysis software has
been developed for accurate modeling and simulation of the structural
information of the transparent film .
visualization is performed via a
high - performance analysis software which allows on - line data acquisition and
processing the sals signal .
the experiments yield information regarding the
trend of the maximum light intensity of the transparent film that can be compared under different processing
conditions .
wavelets have been used successfully in numerous applications ranging
from analysis of flotation froth to countertops [ 23 , 24 ] .
lambert et al . aims at
developing a more accurate measurement of the physical parameters of fractal
dimension , and the size distribution of large fractal aggregates by small - angle
light scattering .
the theory of multiple scattering has been of particular
interest in the case of fractal .
outline how the wavelet transform , a hierarchical
averaging scheme , can be used to perform both spatial and topological
coarse - graining n systems with multiscale physical behavior ,
such as ising lattices and polymer models .
a brief description is given of
a methodology that exploits guided ultrasonic waves , lasers and fiber optics , and
simultaneous time - frequency analysis to interrogate the state of a material ,
component , or structure .
the propagating ultrasound interrogates the host
material in a manner providing a wealth of information when coupled with
application of the gabor wavelet transform to broadband dispersive waveforms .
recent
results are presented pertaining to delamination detection within layered
copper / polymer films .
wavelet analysis ( wa ) is typically
suited in applications where data contains both large and small scales of
variation , such as small - angle light signal .
we presented
a new technique
that can be
used to analyze the
structural information of transparent film
on - line and nonintrusively while
the material is
processing .
the technique is
based on sals ,
optical signal real - time analysis software ,
and wavelet transform
method .
it is shown that the
proposed technique is easy to implement and provides more flexibility , approximating the relation between the intensity signal and the corresponding
variation time . applying this
method to analyze
structural information of transparent
film
will be of
great interest , since it will
contribute information on optical prosperities that have been proven
to be useful
for obtaining deep insights into the molecular and structural
parameters of transparent
film .
in our experiments , the sals signal denoised by wavelet analysis is
better than the signal denoised
by inducing kf factor .
the variation trend of the sals signal becomes clear , and
the exceptional sals signal can be accurately detected by wavelet
decomposition . in this paper ,
the method will be evaluated on the basis of light scattering measurements for
a small range of scattering angles .
these measurements have been taken with a
fast ccd line scan camera and appropriate optics .
an attempt is made to derive
information from these measurements only . with the continuous wavelet transform , sals image
analysis methods are used to process the sals signal .
the purpose of the
present work is to apply the optical image technique to characterize the structural
informal of transparent
film .
in particular , we attempt
to on - line the analysis of
the light intensity signal .
when a light beam passes through a diffusion surface , the
variation of propagation direction of the beam can not be determined by the
principle of geometrical optics because of scattering function of light beams
on diffusion surface . a transparent fluid is an optical phase object . in the
experimental set - up for measuring flow fields in fluid flows by using speckle
interferometry ,
the part of the arrangement for the object light beam is just
like a subjective photographic system .
the speckle displacements can change the intensity
distribution of spatial speckle fields . as a result
, the intensity distribution
of a speckle interferogram is also changed . in this paper ,
this is advantageous to improve the quality of the speckle
interferogram . in our experiments
, device performs real - time image
analysis of the evolving light scattering signal .
the experimental device
incorporates an he - ne laser generator , optics , a ccd camera , and a personal
computer as its major hardware components .
software designed specifically for
this application performs real - time analysis of the light scattering pattern .
figure 1 shows an experimental set - up for small - angle light - scattering
measurement device .
a polarizer and an analyzer are
placed before and after the polymer melts .
the laser light first passes the
polarizer , which removes one orthogonal component of the light .
the other component of light
passes through the polymer melts with resulting scattering due to the
orientation of molecular chain .
the analyzer removes the second component since
it is placed 90 out of phase with respect to the analyzer .
therefore , any light that comes out of the analyzer is entirely due to the
scattering within the polymer melts .
the depolarized intensity of light that
passes through the polarizer , polymer melts , and analyzer is recorded and related to
the orientation of polymer melts .
a ccd camera captures the image , and the total intensity
of the image is determined in every 5 seconds .
we assume that each column of the following matrix represents
the intensities of one observed raman spectrum at the selected wave shifts : ( 1)d=[d1,1d1,2d1,nd2,1d2,2d2,ndm,1dm,2dm , n ] , drmxm .
therefore , each spectrum is
represented by ( m ) number of spectral intensities , and a total of ( n )
spectrum exists .
the dispersion matrix z that represents the variation in the
data is computed as ( 2)z = dtd , zrmxm .
the diagram of multiple scattering is shown in figure 2 . according to the effect of the
sample on the incident light
, the sample can be divided into a surface layer , a
first scattering layer , a second scattering layer , and so forth .
the incident
light first impinges on the surface of the sample of the first scattering layer ( random reflection )
of the medium .
the second one comes from the first scattering layer ( because of
the internal heterogeneity ) and the third in turn .
, is the angle of incident light , and d is the thickness of the sample . because of multiple light scattering
caused by the thickness of the sample , the light scattering images will be dispersion and distortion
models
the measurable intensity of scattered
light is and the factual intensity of scattered light is have the relationship ( 3)is = kfis,where kf is the correcting factor that can be written
as ( 4)kf = e(d / cos )d(cos11 ) { e[d(cos11)1]}1,where is the scattering angle , and is the turbidity of the sample . in a specific point
supposed ( the turbidity of the sample ) is the same , so
correcting factor kf is only with relation to d ( the thickness of the transparent film ) .
spectral analysis and time series
methods are the most commonly used signal processing techniques .
however , these
methods were reported to provide a good solution only in the frequency domain
and poor solution in the time domain .
like the fourier transform ( ft ) , the wavelet transform
( wt ) can be used to measure the frequency content of a signal .
however , the wt differs from
the ft in that it yields frequency
information in a time - localized fashion [ 35 , 36 ] .
this makes the wt far more effective
than ft in identifying time - based phenomena .
given a
time varying signal f ( t ) , wts
consist of computed coefficients of
inner products of the signal and a family of wavelets .
in a continuous wavelet
transform ( cwt ) , the wavelet corresponding to scale ( a ) and time
location ( b ) is ( 5)a , b=1|a|(tba ) , a , br , a0 , where ( a )
and ( b ) are the dilation and translation parameters , respectively .
the
cwt is defined as follows : ( 6)cwt{x(t);a , b}=x(t)a , b*(t)dt , where denotes the complex conjugation . in this
paper ,
morlet
wavelet function was used , which can be represented as ( 7)(t)=et2/2ejw0 t .
its cwt is ( 8)a , b=1ae1/2((tb)/a)2ejw0((tb)/a ) . in ( 8) , ( a ) and ( w0 ) can be changed , each way yields
a different type
of wt .
the sample frequency of the wavelet function and the signal is ( fw ) and ( fs ) , respectively ; the relationship
of the parameter a and w0 is ( 9)a = w0fs2fwf0 , where ( f0 ) is the frequency focused signal
energy . when a = 2 , b = k2 , j , k z , the wt becomes ( 10)j , k=2j/2(2jtk ) .
the discrete wavelet transform ( dwt ) is defined as ( 11)cj , k=f(t)j , k*(t ) , where ( cj , k ) is a time frequency map of the original
signal f ( t ) .
a multiresolution analysis approach is used in this work , in which ( 12)j , k=2j/2(t2jk2j),dj , k=f(t)j , k*(t ) , where ( j , k ) is a discrete scaling function , and ( dj , k ) is a scaling coefficient .
when j = 0 , j , k is the sampled version of the original signal .
the dwt computes wavelet coefficients cj , k for j = 1 , , j , and
scaling coefficients dj , k
are given by ( 13)cj , k=n x[n]hj[n2jk],dj , k=n x[n]gj[n2jk ] , where x[n ] are discrete time signals , hj[n 2k ] are the discrete wavelets , the discrete equivalents
to 2(2(t 2k ) ) , gj[n 2k ] are called scaling sequence .
at each resolution j > 0 , the
scaling coefficients and
the wavelet coefficients are ( 14)cj+1,k=n g[n2k]dj , k , dj+1,k=n h[n2k]dj , k . from a mathematical point of view , the structure of computations in a
dwt is exactly an octave - band filter band .
the terms ( g ) and ( h ) are high - pass and low - pass filters derived
from the analysis wavelet (t ) and the scaling function (t ) . hence , cj ,
k represents the high - frequency components of
the signal f ( t ) .
the results reported in this
study were obtained with polystyrene ( ps ) and high - density polyethylene ( hdpe ) .
as they are commercial polymers that melt at high temperatures , they enabled
the study to be performed under quasi - industrial conditions .
optical system
and the polarization analyzer are detected by a ccd connected to a computer .
we used two kinds of material ( ps and hdpe ) ,
three kinds of rotate speed ( 20 rpm , 24 rpm , and 32 rpm ) , five kinds of vibration
amplitude ( 0.04 mm , 0.08 mm , 0.12 mm , 0.16 mm , and 0.20 mm ) , and five kinds of
vibration frequency ( 5 hz , 8 hz 10 hz , 12 hz , and 15 hz ) . in the experiments ,
second , we changed the amplitude and frequency of the
screw , respectively . at the same time , a ccd camera captured the light scattering image of each
processing condition .
finally , the optical image real - time analysis software characterized the flow field of polymer melts .
the optical image real - time processing software for sals ( see figure 5 ) , which provides a user - friendly
interface already familiar to the users , is based on personal pc platform
running under ms windows operating system .
hardware specifics of a / d and
digital i / o boards which are connected on pc motherboard impose some
constraints and partly determine real - time software structure , especially
disposition of its components at processors .
real - time
visualization of various scattered light image and light intensity matrices is
performed by the host application .
the next step is setting parameters using
corresponding dialog - boxes provided by the host application .
some of these
parameters are vibration parameters ( frequency , amplitude ) , display parameters
( sizing grid , display scale , image translation , and rotate angle ) , and other
parameters ( rotate speed , material , sampling time ) . the light intensity matrix
can be saved on disk of main workstation for further analyses . the software
can measure the signal intensity of light scattering images , draw the
frequency - intensity curves and the amplitude - intensity curves to indicate the
variation of the intensity of scattered light in different processing
conditions , and estimate the hydrodynamic parameters .
so , the system brought
the qualitative analysis of the structural information of transparent film
success .
figure 6(a ) shows a 3d light intensity image of hdpe at 24 rpm screw rotate speed
without vibration .
figure 6(b ) shows light intensity image of hdpe at the same rotate
speed with vibration frequency of 10 hz and vibration amplitude of 0.20 mm . in comparison
with 3d light intensity image without vibration , 3d light intensity image with
vibration has stronger light intensity .
it is illustrated that the orientation
of molecular chain increases because light intensity is proportional
to orientation of molecular chain .
figure 7
shows the variation trend of maximum intensity projection area with the
increase of vibration frequency of ps at 20 rpm rotate speed .
as shown in figure
8 , with the increase of vibration frequency , the maximum intensity projection
area becomes larger .
it is because with the increase of vibration frequency ,
the molecular orientation of polymer melts also increases . as a consequence ,
figure 8
shows the relationship between maximum intensity projection area and vibration
amplitude of hdpe at 24 rpm screw rotate speed . from figure 8 , it is clear that with the increase
of vibration amplitude , the maximum intensity projection area becomes larger .
the molecular orientation of polymer melts increases is also the main reason of
this optical phenomenon .
a signal
including noise can be expressed as ( 15)s(i)=f(i)+e(i ) , i=0, ,n1 , where f ( i ) is the real signal , e(i ) is the noise , is the coefficient of the noise , and s(i ) is the signal including noise . the useful
signal is included in the part of low frequency , and the noise is included in
the part of high frequency .
as shown in figure 9 , we used one - dimensional wavelet
which decomposed
the original signal into three level : ( 16)s = ca3+cd1+cd2+cd3 , where s is the original signal , ca1 , ca2 , ca3 are the approximation coefficients of levels 1 , 2 , and 3 , and cd1 , cd2 , cd3 are the detail coefficients of levels
1 , 2 , and 3 .
the performance of wavelet denoising is comparable to that of
inducing kf correcting factor .
figure 10(a ) is the normal
sals intensity signal . figure 10(b ) is the
sals signal with multiple scattering
noise .
sym6 ,
the multiple scattering
noise is eliminated and the
signal ( see figure 10(e ) ) is
becoming more smooth .
from figures 10(d ) and 10(f ) , the
residuals by wavelet decomposition are smaller than the residuals by inducing kf factor .
wavelet method is more successful in
removing multiple scattering noise than that of
inducing kf correcting factor .
the method of wavelet transform can reduce the ambiguities and accurately
analyze the variation trend of the sals signal .
as shown in figure 11(a ) ,
the variation trend of the original
intensity signal ( s )
is not clear .
sym6 , the variation trend of the intensity is obvious as shown in figure
11(f ) . as shown in figures 11(b)11(f ) , caj ( j = 1 , 2 , 3 , 4 , 5 ) are
the wavelet approximation
coefficients of levels 15 .
it is illustrated that the orientation
of molecular chain increases because light intensity is proportional to
orientation of molecular chain .
the wavelet transform
is used to
purify the original sals signal and diagnose the
exceptional signal .
. these
coefficients can be feature parameters of the inner structural information of
the transparent film for
further analysis . as shown in figure 12(h ) , the exceptional signal takes place at 5001000 seconds .
the
result shows that this technique provides a new tool for diagnosis of exceptional sals
signal .
we
presented a new technique that can be used to characterize the structural
information of transparent film on - line and nonintrusively while the material
is processing with different conditions .
the technique is based on optical sals
image real - time analysis software and wavelet analysis .
visualization is
performed via high - performance analysis software which allows real - time data
acquisition and processing the sals signal .
it is shown
that the proposed technique is easy to implement and provides more flexibility
approximating the nonlinear relation between the maximum intensity signal and
the corresponding vibration intensity ( frequency or amplitude ) . applying this
method to characterize
the flow field of polymer melts
will be of great interest , since it will
contribute information on optical prosperities that have been proven to be
useful for obtaining deep insights into the molecular and structural parameters
of polymers . in our experiments with the increase of vibration intensity ,
the
light intensity matrix becomes stronger and the maximum intensity projection
area becomes larger . because the light intensity is proportional to orientation
of molecular chain , it is illustrated that the orientation of molecular chain
increases . in conclusion , this technique is
believed to be important and promising to on - line characterize the structural
information of transparent film in the multiple - scattering regime .
Output:
| this paper describes an effective on - line polymer characterization technique by using small - angle light - scattering ( sals ) image processing software and wavelet analysis .
the phenomenon of small - angle light scattering has been applied to give information about transparent structures on morphology .
real - time visualization of various scattered light image and light intensity matrices is performed by the optical image real - time processing software for sals .
the software can measure the signal intensity of light scattering images , draw the frequency - intensity curves and the amplitude - intensity curves to indicate the variation of the intensity of scattered light in different processing conditions , and estimate the parameters .
the current study utilizes a one - dimensional wavelet to delete noise from the original sals signal and estimate the variation trend of maximum intensity area of the scattered light .
so , the system brought the qualitative analysis of the structural information of transparent film success . |
PubmedSumm118692 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: the pelvis is a structure between the hip joint and the lumbosacral area , and diverse
muscles that are attached to it adjust their movement .
the location of the pelvis is the
most important element that determines the sagittal alignment and posture of the body1 , and abnormal posture triggers diverse
problems , including flat - back syndrome , cervical kyphosis , local organ ailments such as
uterine prolapse , and gastric herniation2 .
asymmetry in upright posture is associated with various outcomes , such as the decreased
loading of the affected side in stroke ; degenerative changes of the hip , knee , and ankle
joints and spine ; or a leg length discrepancy3 .
the lumbosacral joint affects the lumbar vertebra , and the location
of the joint determines the location of the lumbar vertebra on the upper part .
the angle of
the joint may change according to the location of the pelvis .
the location of the pelvis
also may trigger epidemiological problems in the musculoskeletal system , and forward and
backward tilt exercises of the pelvis may influence the stability of the spine and the
alignment of the body .
therefore , the correct alignment of the pelvis is an important
element of gait , and a incorrectly located pelvis may cause incorrect posture4 .
the pelvis plays a crucial role in posture , and there have been many previous studies of
stability and the posture of the pelvis that improved lumbopelvic stabilization and posture
through bridge exercises5 , mattress
exercises6 , and the use of a swiss
ball7 .
however , these methods have
disadvantages , such as requiring a great deal of time , a large amount of space , and the
active participation of subjects .
in contrast , pelvic adjustment is a therapeutic method
that may be performed in a short time .
there have been many previous studies that examined
the effects of pelvic adjustment on functional leg length inequality8 , foot pressure , and balance9 , but there has been no study that examined the effects of one - time
pelvic adjustment on changes in posture .
therefore , this study intends to examine the
immediate effects of one - time pelvic adjustment on the posture of female university
students .
thirty university female students were selected , and they were equally and randomly
assigned to a pelvic adjustment group , an experimental group , and a stretching group , a
control group .
those who had problems with muscles , the skeletal system , or the neurological
system , those who felt pain in the waist or the pelvis , those who had incorrect posture due
to scars after a burn or a surgical operation , and those who performed regular exercise were
excluded
. a sufficient explanation of the intent of this study and the entire experiment was
given to the subjects , and voluntary consent was obtained from them .
the age , height , and
weight of the experimental group were 22.5 4.9 years old , 159.0 6.3 cm , and 52.1
6.1 kg , and the age , height , and weight of the control group were 22.2 3.3 years old ,
158.4 5.6 cm , and 51.1 8.5 kg .
the c test was used for analysis of their
gender , and an independent t - test was employed the analysis of their age , height , and
weight .
there were no statistically significant differences between the two groups in the
above analyses ( p>0.05 ) , and they were considered homogeneous . for the pelvic adjustment that was applied to the experimental group ,
a high - velocity
low - amplitude technique in keeping with gonstead 's theory was used with the subjects in a
prone position .
the subjects were placed in a prone position , and their pelvic height was
checked .
an impact on the posterior inferior innominate bone was made in the anterior
superior direction , and an impact on the anterior superior innominate bone was made in the
posterior inferior direction .
the therapist put one hand on top of the other hand and placed
them on the posterior superior iliac spine or the ischial spine , and an impact was made
using their weight , gravity , and acceleration8 .
this adjustment was conducted three to five times , and a skilled
physical therapist with more than 10 years of experience performed it .
the control group
stretched the muscles around the pelvis , including the erector spinae muscle , rectus
abdominis muscle , iliacus muscle , psoas major muscle , quadriceps femoris muscle , adductor
muscle , and quadratus lumborum muscle in order to remove any imbalance of the muscles that
might affect pelvic imbalance .
for each muscle stretching , the therapist helped the subject
conduct more stretching exercises in the maximum stretching position , and the subject
maintained the stretching for 10 to 15 seconds .
the subject returned to the starting
position gradually , rested for 5 seconds , and stretched once more .
for the measurement of postural changes , backmapper ( abw , frickenhausen , germany ) , a
three - dimensional spinal diagnostic imaging system , was employed .
backmapper is an apparatus
that precisely measures spinal form , location , and degree of distortion , as if looking at
the spinal form from the backward , forward , downward , and upward directions .
it analyzes
trunk inclination ( tin ) , the inclination of the sagittal plane ; trunk imbalance ( tim ) , the
inclination of the coronal plane ; pelvic position ( ppo ) , the left and right inclination of
the pelvis ; pelvic torsion ( pto ) , the degree of declination of the hip bone ; pelvic rotation
( pro ) , the declination of the pelvis on the horizontal plane ; and the position of the
scapulae ( psa ) , the left and right height of the scapula .
it is a device that may analyze
the distribution of body muscles and fat , as well as the location of the skeleton , using
various variables .
the measured data were analyzed by using the spss 12.0 ko ( spss , chicago , il , usa )
statistical program , and the collected data were presented as means and standard deviations .
a paired t - test was used for analyzing the significance of the differences between subjects
prior to and after the experiment , and an independent t - test was employed for analyzing the
significance of the differences between the two groups .
* p<0.05 ; tin , trunk inclination ; tim , trunk imbalance ; ppo , pelvic position ; pto ,
pelvic torsion ; pro , pelvic rotation ; psa , position of scapulae the adjustment group showd significant differences in tim , ppo , pto , and psa , while the
stretching group showd no significant differences in any items ( p<0.05 ) ( table 1 ) . according to the comparison of the results
from before and after the intervention , as well as the changes between before and after
intervention
, there were no significant differences before intervention , there were
statistical changes in tin , tim , ppo , pto , and psa after intervention , and there were
statistical changes in the tim , ppo , and pto in terms of the changes between before and
after intervention ( p<0.05 ) ( table 2 ) .
correct posture refers to an ideal arrangement of the musculoskeletal system , with the
pelvis at the center .
the pelvis supports the abdominal area and connects the spine to the
lower extremities , and it delivers weight from the spine to the lower extremities in a
standing position , maintains correct posture , and makes the movement of the upper
extremities smooth10 .
the neutral
location of the pelvis is crucial for correct posture and adjusts the upper and lower body
parts during movement , improving the activities of daily living and gait ability11 . for correct posture ,
although there have been many studies of the
pelvis and posture concerning exercise , those on changes in posture immediately after pelvic
adjustment have been rare .
accordingly , this study intended to examine whether postural
changes occurred immediately after pelvic adjustment . according to the analysis of the
results of postural changes after pelvic adjustment via the gonstead technique
, there were
immediate effects in terms of postural changes in female university students in tim , the
inclination of the coronal plane ; ppo , the left and right inclination of the pelvis ; pto ,
the degree of declination of the hip bone ; pro , the declination of the pelvis on the
horizontal plane ; and psa , the left and right height of the scapula .
it is assumed that
pelvic correction could bring about changes in postures as above because the pelvis is an
important structure that supports the spine and conveys body weight to the lower
extremities .
however , the issue of how long pelvic correction will enable maintaining proper
postures should be examined through future studies .
( 2004 ) ,
reported that a correction of rapid speed and low amplitude applied to patients with
subluxation of the sacroiliac joint reduced pain and allowed the patients to return to
work12 ; park et al .
( 2012 ) noted that
pelvic adjustment via the gonstead technique enhanced balance in 20 elderly people9 ; and gong et al .
( 2011 ) observed that pelvic
correction via the gonstead technique reduced functional leg length inequality , which in
turn decreased differences in foot pressure8 .
the results of the previous studies showing that pelvic adjustment
via the gonstead technique reduced leg length differences , improved balance , and decreased
differences in foot pressure are similar to those of the present study : pelvic adjustment
using the gonstead technique corrects female university students ' posture .
nonetheless ,
these previous studies did not observe direct postural changes through pelvic adjustment .
they utilized exercises such as bridge exercises5 , swiss ball exercises7 , and mattress exercises6 for postural stability and muscle balance .
however , they had
disadvantages in that they required a great deal of time , a large space , cognitive ability ,
motor ability , and the active participation of subjects .
therefore , correcting the posture of patients who have degraded cognitive abilities or have
difficulty with active participation in exercise due to decreased motor ability via pelvic
adjustment will be helpful for them , and the researcher hopes this method will be actively
used with these patients .
Output:
| [ purpose ] the purpose of this study was to examine the effects of pelvic adjustment via
the gonstead technique on the posture of female university students .
[ subjects ] the
subjects of this study were 30 female university students who were equally and randomly
allocated to a pelvic adjustment group , an experimental group , and a stretching group , a
control group . [ methods ] using backmapper , their trunk inclination ( tin ) ,
trunk imbalance
( tim ) , pelvic position ( ppo ) , pelvic torsion ( pto ) , pelvic rotation ( pro ) , and position of
their scapulae ( psa ) were evaluated .
[ results ] the adjustment group obtained significant
results in tim , ppo , pto , and psa , while the control group obtained no significant results
for any items .
[ conclusion ] pelvic adjustment via the gonstead technique may be applied as
a method to correct the posture of average adults . |
PubmedSumm118693 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: testicular germ cell tumors ( gct ) are particularly interesting from a clinical perspective because of their exquisite sensitivity to cisplatin based chemotherapy .
approximately 80% of patients with advanced disease can be cured . despite the clinical efficacy of chemotherapy
approximately 10 - 20% of patients diagnosed with a gct will not respond to cisplatin based chemotherapy or will relapse despite further treatment , representing a further challenge for the treating physician .
the principal cause of therapeutic failures in cases of advanced gcts involves the phenomenon of resistance to cisplatin based chemotherapy .
metallothioneins ( mt ) are small , cysteine - rich , metal binding proteins which are involved in trace metal homeostasis and metabolism , detoxification of toxic metals , development of resistance towards metal containing drugs and scavenging of free radicals [ 3 , 4 ] .
it has been suggested that cellular resistance may be mediated by reduced permeability of tumor cells to drugs , accelerated dna repair in cisplatin damaged cells and an increase in chemoprotective thiols including mt [ 5 , 6 ] .
the protective roles of mt against oxidative stress and metal toxicity also suggest that mt may have a functional role in cisplatin resistance .
experimental studies have shown that tumor cell lines with acquired resistance to cytotoxic alkylating agents and cisplatin overexpress mt . however , the functional roles of mts in the clinical setting are less evident . in the present study
, we examined the expression of mt in untreated testicular gct specimens and compared it with the clinical response to cisplatin based chemotherapy in order to investigate the association between mt expression and cisplatin resistance .
the medical records and tumor tissue blocks of 39 primary untreated gct patients who underwent radical orchiectomy were investigated after approval of the study by the local ethics committee of our institution .
median age was 25 years ( range , 17 - 52 ) and median follow
tumors were staged according to the international union against cancer tnm classification and graded according to who histopathological typing [ 9 , 10 ] .
the histological subtype of the study group consisted of 10 seminomas ( 25.7% ) , 10 embryonal cell carcinomas ( 25.7% ) , 3 teratomas ( 7.6% ) and 16 ( 41% ) mixed gcts .
archival histopathological slides from 39 patients which were stained with hematoxylin and eosin ( h - e ) were retrieved and reviewed .
the most representative blocks were selected , cut into 5 m thick sections and placed on poly - l - lysine pretreated glass slides .
immunohistochemistry was performed using the monoclonal primary mouse anti - mt antibody e9 ( zymed laboratories , san francisco , usa ) , which was prepared from immunization of balb / c mice and is able to detect immunreactive mt in formalin fixed paraffin embedded human tissues by the streptavidin - biotin method ( dako , lsab universal kit , carpenteria , usa ) .
all slides were evaluated twice by pathologists on separate occasions without any knowledge of patients clinical outcome .
mt staining intensity in the tumor samples was evaluated semiquantitatively according to the percentage of mt positive cells .
tumors with 75% staining were classified as showing strong staining and graded as [ + + ] , tumors with < 75% immunostaining were classified as showing weak immunostaining and graded as [ + ] and [ - ] if no immunostaining was observed .
standard chemotherapeutic regimen for patients with advanced gct consisted of 3 or 4 cycles of bleomycin , etoposide and cisplatin ( bep ) .
patients considered as complete responders ( cr ) were those with normal tumor markers and no residual mass following chemotherapy , as well as patients who had necrosis and fibrosis of mature teratoma following post - chemotherapy residual mass resection . patients with 50% or more decrease in the diameter of measurable lesions were considered as partial responders .
patients still having elevated levels of tumor markers after chemotherapy and patients with persistent vital carcinoma following post - chemotherapy residual mass resection were considered as non - responders ( nr ) .
the immunostaining characteristics were compared with the clinical response in patients who underwent cisplatin based chemotherapy .
associations between mt expression and the clinicopathological features were assessed by the chi - square test .
archival histopathological slides from 39 patients which were stained with hematoxylin and eosin ( h - e ) were retrieved and reviewed .
the most representative blocks were selected , cut into 5 m thick sections and placed on poly - l - lysine pretreated glass slides .
immunohistochemistry was performed using the monoclonal primary mouse anti - mt antibody e9 ( zymed laboratories , san francisco , usa ) , which was prepared from immunization of balb / c mice and is able to detect immunreactive mt in formalin fixed paraffin embedded human tissues by the streptavidin - biotin method ( dako , lsab universal kit , carpenteria , usa ) .
all slides were evaluated twice by pathologists on separate occasions without any knowledge of patients clinical outcome .
mt staining intensity in the tumor samples was evaluated semiquantitatively according to the percentage of mt positive cells .
tumors with 75% staining were classified as showing strong staining and graded as [ + + ] , tumors with < 75% immunostaining were classified as showing weak immunostaining and graded as [ + ] and [ - ] if no immunostaining was observed .
standard chemotherapeutic regimen for patients with advanced gct consisted of 3 or 4 cycles of bleomycin , etoposide and cisplatin ( bep ) .
patients considered as complete responders ( cr ) were those with normal tumor markers and no residual mass following chemotherapy , as well as patients who had necrosis and fibrosis of mature teratoma following post - chemotherapy residual mass resection . patients with 50% or more decrease in the diameter of measurable lesions were considered as partial responders .
patients still having elevated levels of tumor markers after chemotherapy and patients with persistent vital carcinoma following post - chemotherapy residual mass resection were considered as non - responders ( nr ) .
the immunostaining characteristics were compared with the clinical response in patients who underwent cisplatin based chemotherapy .
associations between mt expression and the clinicopathological features were assessed by the chi - square test .
mt staining was heterogenous within each tumor and subcellulary mt was localized both in the cytoplasm and nucleus in most of the tumor cells .
in general , cytoplasm stained more frequently and none of the tumors showed nuclear staining alone ( figures 1 , 2 , 3 ) . of the 39 tumor samples ,
3 ( 7.7% ) evidenced no mt expression , while 26 ( 66.7% ) and 10 ( 25.6% ) specimens showed [ + ] and [ + + ] staining patterns , respectively .
representative tissue block of an embryonal cell carcinoma with intense [ + + ] mt staining ( x 100 ) .
the distribution of tumors according to histologic subtype and mt expression is listed in table 1 .
although seminomas tend to stain weaker than non - seminomas , the difference of staining intensity between these subtypes was not significant .
the distribution of tumors according to clinical stage and mt staining intensity is presented in table 2 . ninety percent of tumors with clinical stage i or ii disease showed mt expression , whereas 100% of advanced stage tumors showed [ + ] or [ + + ] staining .
no correlation was observed between increasing stage in germ cell tumors and mt staining intensity ( p = 0.09 ) .
distribution of tumors according to histopathological subtype and mt expression correlation of clinical staging and mt immunostaining of germ cell tumors p=0.09 between seminomas and non - seminomas none of the patients received radiotherapy or chemotherapy before orchiectomy .
one patient with advanced seminoma ( clinical stage iii ) received cisplatin based chemotherapy with [ + ] mt staining .
the patient had a complete response following chemotherapy and remained disease free during follow - up .
twenty - two of 29 patients with non - seminomatous germ cell tumors underwent cisplatin based chemotherapy with a median of 3 ( range , 2 - 8 ) cycles .
two patients died of progressive disease , 3 patients had persistently elevated tumor markers after chemotherapy and 1 had a vital carcinoma following post - chemotherapy residual mass excision .
there was no significant relationship between the presence of staining for mt and the response to chemotherapy ( table 3 ) ( p = 0.53 ) .
mt expression and clinical response to cisplatin based chemotherapy cr : complete responders ; nr : non - responders
the immunohistochemical staining patterns of mt have been reported with archival paraffin embedded tumor tissues in various types of human tumors . it was suggested that overexpression of mt in ovarian , prostate and colon tumors could have protective effects against cisplatin [ 12 , 13 , 14 ] , whereas other reports did not support this perception
. a number of in vitro experimental studies have shown that tumor cell lines with acquired resistance to cisplatin overexpress mt [ 8 , 16 ] .
however , other investigators have reported an inverse correlation between resistance and mt or total amount of sulphydryl groups both in cell lines and clinical samples [ 17 , 18 ] .
thus , experimental evidence suggesting a role of mt in cisplatin resistance appears to be inconclusive .
. however , the data on the predictive value of mt expression regarding cisplatin resistance has been divergent [ 18 , 2022 ] . in a previous study , the intensity and extent of mt staining assessed in tissue sections of 9 embryonal cell carcinomas .
the authors observed a considerable heterogeneity in the mt content among individual cells and proposed that mt may be considered as an onco - developmental product .
the same investigators later assessed the degree of mt immunostaining in 33 primary testicular gct specimens .
non - seminomas tended to stain heavily for mt , especially in the more advanced stages .
three patients with advanced seminoma and 15 of 23 patients with non - seminomatous testis tumors received cisplatin based chemotherapy .
one of the two patients died due to progressive disease during initial chemotherapy and 2 patients with resistance to first line chemotherapy were reported to show heavy mt staining . in that study , although a direct correlation between cisplatin resistance and mt content had not been established , the authors highlighted the possibility of such a relationship depending on inferential clinical data .
in contrast , in 77 patients with germ cell testicular tumors , high mt immunostaining was found to predict a better response rate to chemotherapy , opposing the hypothesis that mt over - expression contributes to cisplatin resistance in this tumor type .
the authors attributed these discrepancies to the immunohistochemical staining techniques . moreover , an intense mt staining in 85% of seminomas was observed and 78% of poor responders to chemotherapy showed no or little staining for mt ( all with non - seminomas of advanced stage ) . according to these findings , authors suggested that mt expression might be a marker of chemo - sensitivity and its absence , when it occurs , indicated a resistant tumor type .
investigated mt levels and functionality both in the cell line model and in 14 specimens of human gct , as well as in post - chemotherapy residual vital gct .
metallothionein levels of cell lines were found to be inversely correlated with sensitivity to cisplatin . in agreement with the in vitro data , immunohistochemical detection of mt was reported to be high in 11/14 primary human germ cell tumors .
no difference was documented in mt protein expression between primary gct of responding ( n = 6 ) or non - responding ( n = 8) tumors to cisplatin based chemotherapy .
interestingly , all post - chemotherapy residual vital gcts tested showed a decreased or undetectable level of mt expression compared with their primary tumors .
the authors concluded that mt expression in primary gcts did not discriminate between responding and non - responding patients , and therefore could not be used to predict response to chemotherapy . in another study , the immunohistochemical staining pattern of proteins involved in the regulation of apoptosis , cell cycle control , and drug export and inactivation were investigated in samples of unselected gcts ( n = 20 ) in patients achieving a complete remission following chemotherapy ( n = 12 ) and in chemotherapy refractory patients ( n = 24 ) .
mature teratoma components ( n = 10 ) within tumor samples from all groups were analyzed separately .
metallothionein immunostaining was identified in 35% , 58% and 45% of unselected gcts , chemotherapy responsive tumors and chemotherapy refractory tumors , respectively . in that study
, no significant difference was observed in any of the potential regulators of chemotherapy sensitivity , including mts , between the samples of responding or chemotherapy refractory tumors . because mt was detectable in tumors regardless of treatment outcome or histology
, the authors suggested that the presence of mt immunostaining was not sufficient to confer resistance . in the present study , we examined the immunuhistochemical expression pattern of mt in a cohort of testis tumor patients and also focused explicitly on the implications of mt overexpression in the subgroup of patients who received cisplatin based chemotherapy . despite the findings of eid et al . ,
who reported that mt overexpression in gct indicates a favorable response to cisplatin therapy , no such relationship was detected in our patient population using monoclonal antibody e9 .
consistent with the findings of three previous studies [ 2022 ] , we found no significant association between overexpression of mt and sensitivity to cisplatin based chemotherapy . in the present series , of the 23 patients receiving cisplatin based chemotherapy , 17 achieved a complete response .
of those , 16 ( 94% ) showed weak or strong mt staining and all of the non - responders showed [ + ] or [ + + ] mt staining .
on the other hand , it is noteworthy that all of the patients who failed to achieve a complete response following cisplatin based chemotherapy had some degree of mt staining .
the process of cisplatin resistance is determined by multiple factors on different cellular levels , such as changes in cellular drug uptake and efflux , leading to decreased drug accumulation .
nevertheless , a direct measure of the correlation between cisplatin resistance and mt content in tumors may be obscured by the complexity of cellular defenses against toxicity .
furthermore , genetic variability of the patients themselves might also affect the expression of mt or sensitivity to cisplatin .
it appears that in human gcts , mt may be associated , but is certainly not required , for the induction of resistance to cisplatin .
in addition , the controversial results of the previous studies could possibly be attributed to the methods applied using antibodies that were unable to distinguish specific mt isoforms , metal bound and metal free forms of the protein .
subcellular distribution of mt differs between cell types and this may be more important than mt levels in cellular protection against cisplatin damage . the low number of patients may be considered the limiting factor for the power of the present study . in particular , the lack of statistical significance between the groups in the present study might be attributed to the inclusion of limited number of patients .
mt expression in primary germ cell tumors did not differ between responding and non - responding patients and therefore may not be useful in predicting response to chemotherapy .
constitutive expression of mt does not seem to depend on the phenotype of the tumor , and mechanisms of drug resistance in primary testicular germ cell tumors is probably multifactorial .
further research is required to investigate the molecular mechanisms behind the resistance of cisplatin in gct .
Output:
| introductionthe protective roles of metallothioneins ( mt ) against metal toxicity suggest that mt may have a functional role in cisplatin resistance . the aim of this study was to investigate the expression of mt in specimens of germ cell tumors and compare it with clinical sensitivity to cisplatin based chemotherapy.material and methodstissue blocks of primary gct specimens obtained from 39 patients
were examined immunohistochemically for mt expression .
staining intensity was evaluated according to the percentage of mt positive cells and graded as [ - ] , [ + ] and [ + + ] .
the staining characteristics were compared with the clinical response to chemotherapy.resultsof the 39 tumors , 3 evidenced no mt expression while 26 and 10 specimens showed [ + ] and [ + + ] staining , respectively . although seminomas tend to stain weaker than non - seminomas , the difference of staining between them was not significant ( p = 0.19 ) .
of the 39 patients , 23 underwent cisplatin based chemotherapy .
of those , 6 progressed and 17 achieved complete remission
. of the non - responders , 5 showed [ + ] and 1 showed [ + + ] staining .
six of the responders showed [ + ] , 10 had [ + + ] and 1 showed no staining .
no association was found between mt staining and chemo - sensitivity ( p = 0.53).conclusionsmt expression in primary germ cell tumors did not differ between responding and non - responding patients and therefore may not be useful in predicting response to chemotherapy . |
PubmedSumm118694 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: amino acids are important biomolecules that both serve as building blocks of proteins and are intermediates in various metabolic pathways .
they serve as precursors for synthesis of a wide range of biologically important substances including nucleotides , peptide hormones , and neurotransmitters . moreover , amino acids play important roles in cell signaling and act as regulators of gene expression and protein phosphorylation cascade , nutrient transport and metabolism in animal cells , and innate and cell - mediated immune responses .
amino acids are mainly obtained from proteins in diet and the quality of dietary protein is assessed from essential to nonessential amino acid ratio .
high quality proteins are readily digestible and contain the dietary essential amino acids ( eaa ) in quantities that correspond to human requirements . proteins , the most abundant macromolecules found in biological systems , are present in diverse forms such as structural elements , enzymes , hormones , antibodies , receptors , signaling molecules , and so forth , having specific biological functions .
protein is necessary for key body functions including provision of essential amino acids and development and maintenance of muscles .
inadequate uptake of quality proteins and calories in diet leads to protein - energy malnutrition ( pem ) ( or protein - calorie malnutrition , pcm ) which is the most lethal form of malnutrition / hunger .
kwashiorkor and marasmus , the extreme conditions of pcm mostly observed in children , are caused by chronic deficiency of protein and energy , respectively .
about 870 million people in the world are suffering from chronic protein malnutrition ; 80% of children suffering from pcm are from developing countries [ 3 , 4 ] .
fish , in this context , can play a vital role as it is an important and cheaper source of quality animal proteins .
therefore , there is a need to generate and document nutritional information on the numerous varieties and species of food fishes available . in comparison to the other sources of dietary animal proteins ,
consumers have wide choice for fish as far as affordability is concerned as there are many varieties and species of fishes available , especially in the tropical countries .
the present study was undertaken to generate information on protein content and amino acid composition of important food fishes with the objective of enhancing the scope for their utility in clinical nutrition for dietary counseling .
the authors confirm that all the research done meets the ethical guidelines , including adherence to the legal requirements of the study country .
freshly caught fishes were collected from either the landing centers or the local fish markets and were brought to the laboratory in ice .
a total of 27 species included for amino acid profiling were the carps catla catla , labeo rohita , and cirrhinus mrigala , catfishes sperata seenghala , heteropneustes fossilis , and clarias batrachus , the small indigenous fishes amblypharyngodon mola , puntius sophore , anabas testudineus ( all fresh water fishes ) , and tenualosa ilisha ( anadromous ) , the cold water fishes oncorhynchus mykiss , tor putitora , schizothorax richardsonii , neolissochilus hexagonolepis , and cyprinus carpio ; the marine fishes thunnus albacares , stolephorus waitei , stolephorus commersonii , rastrelliger kanagurta , nemipterus japonicas , sardinella longiceps , katsuwonus pelamis , epinephelus spp . , leiognathus splendens , and trichiurus lepturus , and the shellfishes crassostrea madrasensis , perna viridis .
fishes were cleaned , descaled , degutted , minced , homogenized , and stored at 40c until used .
amino acid composition was determined following ishida et al . and has been described earlier .
briefly , muscle protein was hydrolyzed with 6n hydrochloric acid at 110c under anaerobic condition for 24 h. the hydrolyzed samples were neutralized with 6n naoh and were derivatized using a kit ( accq - fluor reagent , wat052880 , waters ) .
the derivatized samples were injected in high performance liquid chromatography ( hplc ) ( 1525 , waters ) equipped with a c18 rp column and a fluorescence detector ( 2475 , waters ) .
the amino acids were identified and quantified by comparing with the retention times and peak areas of standards ( wat088122 , waters ) . for the tryptophan analysis , minced meat was digested with 5% ( w / v ) naoh for 24 h and neutralized to ph 7.0 with 6n hcl .
tryptophan content was measured spectrophotometrically at 530 nm . all data have been presented as mean standard deviation .
the physiological role of dietary proteins is to provide substrates required for the synthesis of body proteins and other metabolically important nitrogen - containing compounds .
therefore , the content of the nutritionally indispensable amino acids ( aas ) in food proteins is usually the primary determinant of nutritional quality of protein .
moreover , amino acids are associated with health issues and amino acid deficiencies lead to a number of diseases . hence ,
knowledge of the amino acid composition of foods serves as a basis for establishing their potential nutritive value .
it may also allow evaluation of changes in nutritive value that may arise in the preparation , processing , and storage of foods .
aas have been traditionally classified as nutritionally essential ( eaa ) , nonessential ( neaa ) or conditionally essential ( ceaa ) .
arginine , cystine , histidine , leucine , lysine , methionine , threonine , tryptophan , tyrosine , and valine are the eaas , glutamine , glutamic acid , glycine , proline , and taurine are ceaa , and aspartic acid , serine , and alanine are the neaa for human nutrition .
however , recently the concept of functional amino acids ( faas ) has been proposed .
faas are those which participate and regulate key metabolic pathways to improve health , survival , growth , development , lactation , and reproduction of the organisms [ 1 , 12 ] .
the faas also hold great promise in prevention and treatment of metabolic diseases ( e.g. , obesity , diabetes , and cardiovascular disorders ) , intrauterine growth restriction , infertility , intestinal and neurological dysfunction , and infectious disease .
arginine , cystine , leucine , methionine , tryptophan , tyrosine , aspartate , glutamic acid , glycine , proline , and taurine have been classified as faa in human nutrition .
fish is an important source of quality animal proteins and it has been reported that fish protein has greater satiety effect than other sources of animal proteins like beef and chicken . in comparison to the other sources of dietary animal proteins ,
consumers have wide choice for fish as far as affordability is concerned as there are many varieties and species of fishes available , especially in the tropical countries . here , we report the crude protein content and amino acid composition of 27 food fishes from the indian subcontinent ( tables 1 and 2 ) which could be useful in patient counseling and recommending species for patients with specific requirements and thus could be useful in clinical medicine . the distributions of amino acid in different species are discussed below .
there was no appreciable variation in amino acid composition of fishes of the same species from different locations .
arginine plays an important role in cell division , wound healing , ammonia removal , immune function , and hormone release .
it is also the precursor for biological synthesis of nitric oxide which plays important roles in neurotransmission , blood clotting , and maintenance of blood pressure .
it is supplemented for recovery in a number of diseases like sepsis , preeclampsia , hypertension , erectile dysfunction , anxiety , and so forth .
arginine contents of cold water fishes o. mykiss ( 6.5 0.3 g 100 g protein ) , t. putitora , and n. hexagonolepis were found to be very high among the fishes studied and can be recommended in arginine deficiency .
similar levels of arginine have been reported in the small forage fish capelin ( mallotus villosus ) ( 5.70 0.02% ) .
leucine is the only dietary amino acid that can stimulate muscle protein synthesis and has important therapeutic role in stress conditions like burn , trauma , and sepsis . as a dietary supplement
, leucine has been found to slow the degradation of muscle tissue by increasing the synthesis of muscle proteins .
leucine was very high in marine fishes s. waitei and r. kanagurta ( 10.4 0.4 and 10.3 0.4 g 100 g protein , resp . ) , carps l. rohita and c. mrigala , and catfishes c. batrachus and h. fossilis ( table 1 ) which is higher than european seabass ( 7.21 0.56% ) , gilthead seabream ( 7.27 0.80% ) , and turbot ( 5.91 0.69% ) .
methionine is used for treating liver disorders , improving wound healing , and treating depression , alcoholism , allergies , asthma , copper poisoning , radiation side effects , schizophrenia , drug withdrawal , and parkinson 's disease .
methionine content of the marine fish s. waitei ( 4.0 0.4 g 100 g protein ) and cold water fish t. putitora ( 3.6 0.3 g 100 g protein ) was found to be highest among the fishes and is even higher than that found in mutton and comparable to that of murrels channa striatus ( 3.4 0.11% ) , channa micropeltes ( 4.0 0.91% ) , and channa lucius ( 3.6 0.16 ) .
glutamic acid plays an important role in amino acid metabolism because of its role in transamination reactions and is necessary for the synthesis of key molecules , such as glutathione which are required for removal of highly toxic peroxides and the polyglutamate folate cofactors .
this amino acid was found to be one of the most abundant amino acids in the carps c. catla , l. rohita , and c. mrigala and catfishes c. batrachus and h. fossilis ( table 1 ) .
similar values of glutamic acid have been reported in other fish species like mackerel and red salmon and in beef also .
glycine plays an important role in metabolic regulation , preventing tissue injury , enhancing anti - antioxidant activity , promoting protein synthesis and wound healing , and improving immunity and treatment of metabolic disorders in obesity , diabetes , cardiovascular disease , ischemia - reperfusion injuries , cancer , and various inflammatory diseases .
the catfish h. fossilis was found to contain the highest amount of glycine followed by a. testudineus ( table 1 ) which was much higher than the glycine content of european seabass , gilthead seabream , turbot , channa striatus , channa micropeltes , and channa lucius [ 18 , 21 ] .
thus , tryptophan supplementation has been used to increase serotonin production in attempt to increase tolerance to pain .
tryptophan is also the precursor of melatonin , tryptamine , and kynurenine and has an important role in the functioning of neurotransmitters like dopamine and nor - dopamine .
tryptophan supplement is used in treatment of pain , insomnia , depression , seasonal affective disorder , bulimia , premenstrual dysphoric disorder , attention deficit / hyperactivity disorder , and chronic fatigue .
the fish t. putitora was found to contain the highest amount of tryptophan among the fishes studied ( table 1 ) .
histidine plays multiple roles in protein interaction and is also a precursor of histamine .
it is also needed for growth and repair of tissue , for maintenance of the myelin sheaths , and in removing heavy metals from the body .
the small indigenous fishes a. testudineus , a. mola , and p. sophore were also found to be rich in histidine .
lysine is an eaa which is extensively required for optimal growth and its deficiency leads to immunodeficiency .
lysine content was very high in s. commersonii ( 16.1 0.9 g 100 g protein ) and t. putitora ( 9.4 0.6 g 100 g protein ) .
the amino acid content of t. putitora was similar to that of channa striatus ( 9.7 0.57% ) , channa micropeltes ( 10.9 1.05% ) , and channa lucius ( 10.1 1.42% ) .
threonine is used for treating various nervous system disorders including spinal spasticity , multiple sclerosis , familial spastic paraparesis , and amyotrophic lateral sclerosis .
threonine content of s. waitei was found to be highest among the fish species studied ( table 1 ) .
isoleucine is a branched chain amino acid and is needed for muscle formation and proper growth .
chronic renal failure ( crf ) patients on hemodialysis have low plasma level of the branched chain amino acids ( bcaa ) leucine , isoleucine , and valine .
the abnormalities in the plasma amino acid pool can be corrected with appropriate high - protein supplements .
o. mykiss was found to contain the highest amount of isoleucine among the fish species studied ( 6.5 g 100 g protein ) followed by l. rohita and can be used for isoleucine supplementation .
although neaa are synthesized de novo in the body , some of the nutritionally neaa play important roles in regulating gene expression and micro - rna levels , cell signaling , blood flow , nutrient transport and metabolism in animal cells , development of brown adipose tissue , intestinal microbial growth and metabolism , anti - oxidative responses , and innate and cell - mediated immune responses .
aspartic acid ( faa ) is the precursor of aas methionine , threonine , isoleucine , and lysine and regulates the secretion of important hormones .
similarly , serine is the precursor of glycine , cysteine , and tryptophan and plays many important roles in cell signaling .
aspartic acid and serine content of s. commersonii was found to be highest among the fishes studied , followed by r. kanagurta .
the knowledge base enriched with amino acid composition data of 27 important food fishes would be useful in clinical nutrition for issuing patient advisory , dietary guidance , and counseling .
although cooking and boiling cause loss in the content of amino acids to varied degrees , the final content is proportional to the crude content . therefore , in general , the cold water species can be recommended for lysine and aspartic acid , marine fishes for leucine , small indigenous fishes for histidine , and the carps and catfishes for glutamic acid and glycine .
however , for specific patient need the amino acid composition data of individual species , as given in table 1 , would be useful .
Output:
| proteins and amino acids are important biomolecules which regulate key metabolic pathways and serve as precursors for synthesis of biologically important substances ; moreover , amino acids are building blocks of proteins .
fish is an important dietary source of quality animal proteins and amino acids and play important role in human nutrition . in the present investigation , crude protein content and amino acid compositions of important food fishes from different habitats have been studied .
crude protein content was determined by kjeldahl method and amino acid composition was analyzed by high performance liquid chromatography and information on 27 food fishes was generated .
the analysis showed that the cold water species are rich in lysine and aspartic acid , marine fishes in leucine , small indigenous fishes in histidine , and the carps and catfishes in glutamic acid and glycine .
the enriched nutrition knowledge base would enhance the utility of fish as a source of quality animal proteins and amino acids and aid in their inclusion in dietary counseling and patient guidance for specific nutritional needs . |
PubmedSumm118695 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: evidence indicates that inflammation may actively participate in the development and progression of atherosclerosis and cardiovascular disease processes .
it is well recognized that high - sensitivity c - reactive protein ( hs - crp ) , an acute - phase of inflammatory marker , might be associated with increased risk of cardiovascular events [ 2 , 3 ] .
recently , it has been shown that crp could reduce the nitric oxide ( no ) bioavailability by itself , which would induce endothelial and cardiovascular dysfunctions .
venugopal et al . demonstrated that crp directly decreased endothelium type of no synthase ( enos ) expression in human aortic endothelial cells in vitro .
qamirani et al . showed that crp inhibited endothelium - dependent no - mediated dilatation of porcine coronary arterioles . in a clinical study , it was also demonstrated that increased levels of hs - crp were associated with reduced endothelium - mediated dilatory responses of the arteries .
however , the precise role of inflammation in the circulatory dysfunction in hypertension remains unclear .
it has been proposed that abnormalities in physical properties of the cell membranes may underlie the defects that are strongly linked to hypertension , stroke , and other cardiovascular disease conditions [ 79 ] .
an electron spin resonance ( esr ) and spin - labeling method has been developed to evaluate the membrane fluidity ( a reciprocal value of membrane microviscosity ) and perturbations of the membrane function by external agents [ 8 , 9 ] .
the membrane fluidity is a physicochemical feature of biomembranes and is an important factor in modulating the cell rheologic behavior [ 8 , 9 ] . using the esr method ,
we have been performing a series of experiments regarding the membrane fluidity of red blood cells ( rbcs ) in hypertension and have shown that membrane fluidity was significantly lower in hypertensive subjects than in normotensive subjects , particularly in the elderly [ 1015 ] . because the deformability of rbcs might be highly dependent on the membrane fluidity [ 8 , 9 ] , the reduction in membrane fluidity could cause a disturbance in the blood rheologic behavior and the microcirculation , which might contribute to the pathophysiology of hypertension and other circulatory disorders . in the present study , in order to assess the role of inflammation in the regulation of membrane function in hypertension in the elderly , we investigated the relationships between plasma hs - crp and membrane fluidity of rbcs in hypertensive and normotensive elderly men using the esr and the spin - labeling method .
a total of 29 men with untreated essential hypertension ( age 63 2 years old ) were studied and compared with 18 age - matched normotensive men ( age 64 2 years old ) ( table 1 ) .
they had similar life styles and dietary habits and were instructed to avoid any changes in dietary habits at least 12 weeks before the study .
the study was approved by a local research committee of kansai university of health sciences . written informed consent was obtained from all participants when they were informed about the nature and objective of the study .
we evaluated the values of outer and inner hyperfine splitting ( 2t|| and 2t in tesla ( t ) , resp . ) in the esr spectrum for the spin label agents ( 5-nitroxide stearate , aldrich co. , ltd . ,
milwaukee , wi , usa ) ( figure 1 ) , and calculated the order parameter ( s ) [ 1016 ] .
the greater the value of the order parameter ( s ) was , the lower the membrane fluidity of rbcs was .
the plasma levels of no metabolites ( nitrite and nitrate ) were measured according to the method described previously .
the differences between hypertensive and normotensive men were analyzed using an unpaired student 's t - test .
linear regression analysis was performed to assess the relationships between membrane fluidity ( order parameter : s ) of rbcs and plasma hs - crp or no metabolite levels .
multivariate regression analysis with membrane fluidity ( order parameter : s ) of rbcs as a dependent variable and plasma hs - crp , age , body mass index ( bmi ) , hypercholesterolemia ( more than 220 mg / dl ) , hyperglycemia ( more than 110 mg / dl ) , and systolic blood pressure as independent variables was also performed .
the order parameter ( s ) for 5-nitroxide stearate in the esr spectra of rbcs was significantly higher in hypertensive elderly men ( ht ) than in normotensive elderly men ( nt ) ( ht 0.729 0.002 , mean sem , n = 29 , nt 0.718 0.002 , n = 18 , p < 0.01 ) .
the finding indicated that membrane fluidity of rbcs was significantly lower in hypertensive elderly men than in normotensive elderly men .
the plasma hs - crp levels were significantly higher in hypertensive elderly men than in normotensive elderly men ( ht : 0.157 0.022 mg / dl , n = 29 , nt : 0.072 0.009 mg / dl , n = 18 , p < 0.01 ) .
in contrast , the plasma no metabolites were lower in hypertensive elderly men than in normotensive elderly men ( ht : 36.0 2.4
mol / l , n = 29 , nt : 52.5 5.2
in addition , in the overall analysis of hypertensive and normotensive elderly men , plasma hs - crp levels were inversely correlated with plasma no metabolites ( r = 0.291 , n = 47 , p < 0.05 ) ( figure 2 ) .
the order parameter ( s ) of rbcs was significantly correlated with plasma hs - crp levels ( r = 0.416 , n = 47 ,
p < 0.01 ) ( figure 3 ) and was inversely correlated with plasma no metabolite levels ( r = 0.362 , n = 47 , p < 0.05 ) . in a multivariate regression analysis after adjustment for general risk factors , plasma hs - crp was an independent determinant of membrane fluidity ( order parameter : s ) of rbcs ( table 2 ) .
evidence indicates that hs - crp , an acute - phase of inflammatory marker , might be associated with increased risk of cardiovascular events [ 2 , 3 ] . in the present study
, we assessed the relationships between plasma hs - crp levels and the membrane fluidity ( a reciprocal value of membrane microviscosity ) of rbcs in hypertensive and normotensive elderly men using the esr and the spin - labeling method .
the present study showed that the membrane fluidity of rbcs was decreased in hypertensive elderly men compared with normotensive elderly men .
the result might be consistent with our previous findings showing that the cell membranes were stiffer and less fluid in hypertensive subjects [ 1015 ] .
plasma hs - crp levels were significantly higher in hypertensive elderly men than in normotensive elderly men and correlated with the order parameter ( s ) of rbcs , indicating that the reduced membrane fluidity of rbcs might be associated with elevated inflammatory status .
to our knowledge , this is the first report demonstrating that crp might have a close correlation with membrane fluidity of rbcs in humans .
multivariate regression analysis also showed that plasma hs - crp was an independent determinant of membrane fluidity of rbcs after adjustment for general risk factors . because the deformability of rbcs might be highly dependent on the membrane fluidity [ 8 , 9 ]
, the reduction in membrane fluidity associated with increased hs - crp levels could cause a disturbance in the blood rheologic behavior and the microcirculation .
it was shown that shear rate , shear stress , and blood viscosity were correlated with membrane fluidity of rbcs .
the finding proposed that in vivo shear forces might participate in the control of rbc membrane fluidity and that rbcs might adapt their membrane properties to blood flow conditions .
it was also demonstrated that rbc membranes might become more rigid after myocardial infarction , which could contribute to the decreased rbc deformability and the increased blood viscosity in this group of patients . on the other hand , cazzola et al .
reported that the membrane fluidity of rbcs was decreased in the obese subjects and proposed that a decrease in rbc membrane fluidity could contribute to a reduction of the rate of blood flow and the oxygen diffusion through the rbc membranes and its exchange with tissues .
it might be , therefore , possible that alterations in rbc membrane fluidity with elevated hs - crp levels would be strongly linked to the progression of circulatory disorders .
recently , it was demonstrated that crp might directly impair the nos expression in human aortic endothelial cells in vitro .
it was also shown that endothelium - dependent vasodilatory responses or microvascular endothelial functions were reduced in humans with elevated plasma hs - crp levels [ 6 , 21 ] .
the results of the present study demonstrated that plasma hs - crp levels were inversely correlated with plasma no metabolites in the overall analysis of hypertensive and normotensive elderly men .
one hypothesis is that higher hs - crp levels could be accompanied by the reduced no production and endothelial dysfunction . in a study presented earlier
, it was shown that an no donor significantly improved membrane fluidity of rbcs in hypertensive subjects , indicating that no could have a beneficial effect on the rheologic behavior of rbcs and the microcirculation in hypertension [ 1315 ] .
we also demonstrated that the reduced membrane fluidity of rbcs was associated with the decreased plasma no metabolites in overall analysis of hypertensive and normotensive elderly men , which might be consistent with our previous findings [ 13 , 17 ] .
it is , therefore , strongly suggested that the effects of crp on membrane fluidity of rbcs might be mediated , at least in part , by the impaired no bioavailability , although direct actions of crp on membrane structural and functional properties can not be excluded .
further studies should be performed to assess more precisely the relationships between crp and no and their role in the regulation of membrane functions and circulatory mechanisms in hypertension .
the results of the present study demonstrated that plasma hs - crp levels were elevated in hypertensive elderly men compared with normotensive elderly men .
in addition , it was shown that the reduced membrane fluidity of rbcs was correlated with higher plasma hs - crp and lower plasma no metabolite levels , indicating that abnormalities in rbc membranes might be associated with increased inflammatory status and endothelial dysfunction in hypertension .
although this is a cross - sectional and correlative study in japanese men , the results of the present study suggest that crp might have a close correlation with the rheologic behavior of rbcs and the microcirculation and would contribute , at least in part , to the circulatory dysfunctions and vascular complications in hypertensive elderly men .
moreover , a better knowledge of the inflammatory biomarker and cellular mechanisms underlying membrane abnormalities could provide useful information concerning the pathogenesis , treatment , and prognosis of hypertension in the elderly .
Output:
| recent evidence indicates that high - sensitivity c - reactive protein ( hs - crp ) , an acute phase of an inflammatory marker , might be associated with atherosclerosis , hypertension , and other cardiovascular diseases .
the present study was performed to assess the possible link between plasma hs - crp and membrane fluidity ( a reciprocal value of membrane microviscosity ) in hypertensive elderly men .
we measured the membrane fluidity of red blood cells ( rbcs ) in hypertensive and normotensive elderly men using an electron spin resonance and spin - labeling method .
membrane fluidity of rbcs was decreased in hypertensive elderly men compared with normotensive elderly men .
plasma hs - crp levels were significantly higher in hypertensive elderly men than in normotensive elderly men .
in contrast , plasma nitric - oxide- ( no- ) metabolite levels were lower in hypertensive elderly men than in normotensive elderly men .
the reduced membrane fluidity of rbcs was associated with increased plasma hs - crp and decreased plasma no - metabolite levels . in a multivariate regression analysis ,
plasma hs - crp was an independent determinant of membrane fluidity of rbcs after adjustment for general risk factors .
the results suggest that crp might have a close correlation with the rheologic behavior of rbcs and the microcirculation and would contribute , at least in part , to the circulatory dysfunction and vascular complications in hypertensive elderly men . |
PubmedSumm118696 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: high quality infection control is of great importance in dentistry for the safety and protection of both patients and health care workers , including those in training .
adherence to hospital guidelines , taking universal precautions , and ensuring routine use of personal protective equipment is actively promoted , but there is always a risk that an adverse incident can occur , thus exposing the health care worker to body fluids , including blood products , and putting them at risk of infection including contracting a blood - borne virus .
it is important that systems are in place to minimize such incidents and to deal with them appropriately when they occur .
recording of incidents is an established process to ensure that the national health service ( nhs ) learns from adverse incidents , which then in turn inform processes to minimize their occurrence in future.1 the world health organization defines an adverse incident as an injury related to medical management , in contrast with complication of disease .
adverse events may be preventable or non - preventable.2 within england , each hospital trust has its own policy in place for acknowledging , reporting , and investigating such incidents .
king s college hospital nhs trust defines an adverse incident as an unintended event or circumstance which adversely affects patients , staff , visitors or the trust s assets / reputation or has potential to do so .
the trust also has a framework in place to report any near miss event as well as a potential hazard .
it has been suggested that within the dental environment , compared with many other health care settings ,
sharps injuries are more likely , due to a small operating field , frequent patient movement , and the variety of sharp dental instruments used in everyday practice.3 a busy dental teaching hospital with a large patient catchment area where there is a high incidence and prevalence of blood - borne viruses4,5 further increases the risk of adverse incidents occurring due to relative operator inexperience , a high turnover of staff , and an exceptionally high intake of patients . all health care professionals and students carrying out exposure - prone procedures need to have full health clearance before commencement of an appointment .
they must provide evidence that they are noninfectious for human immunodeficiency virus ( hiv , antibody negative ) , hepatitis b virus ( surface antigen negative or , if positive , e - antigen negative with a viral load of 10 genome equivalents / ml or less ) and hepatitis c virus ( antibody negative or , if positive , negative for hepatitis c rna).4 supporting the above requirement for full health clearance , are the estimated published figures , ie , 85,000 of uk residents are now living with hiv , with up to 25% being unaware that they are infected with the virus .
the risk of seroconversion following a percutaneous injury with a needle or sharp device visibly contaminated with blood has been estimated as 1 in 3 for hepatitis b virus , 1 in 30 for hepatitis c virus , and 1 in 300 for hiv .
these statistics re - enforce and emphasize the need for high quality infection control and the need to prevent the occurrence of adverse incidents.5 when an adverse incident occurs at kings college london , the first priority of those involved is to make the environment safe and treat any injuries caused by the incident.6 the incident must be reported as soon as it is safe to do so , and within one working day .
any staff or student involved in , witness to , or made aware of an adverse incident has a duty to report it . if and when an incident occurs , the local manager should be informed at the earliest opportunity . the incident is then required to be documented using the trust s online datixweb form ( http://datix / datix / live / index.php ) . alternatively , if the web is unavailable , a paper form should be completed and submitted to the risk management department . all incidents that have been formally reported at the dental hospital since 2005
have been uploaded onto this standardized trust software , making the collection of data for this research efficient .
incidents being graded by risk managers as red , amber , yellow , or green.6 adverse incidents , or near misses , are to be treated and investigated at a level correspondent with their seriousness , and a formal process is put in place whereby the reporter has two working days to confirm with the risk management department , and the relevant divisional manager ( head of dental nursing ) is ultimately responsible for confirming whether the incident is declared as a serious adverse incident.6 this research set out to answer the following questions :
what are the trends in the reported number and rate of adverse incidents over the last six years?what are the trends in the reported number and rate of adverse incidents , within the calendar year?which procedures are most commonly associated with adverse incidents?what is the context of reported incidents?what is the outcome of reported incidents?in light of the findings , what are the recommendations for future action ?
what are the trends in the reported number and rate of adverse incidents over the last six years ?
what are the trends in the reported number and rate of adverse incidents , within the calendar year ?
which procedures are most commonly associated with adverse incidents ? what is the context of reported incidents ?
what is the outcome of reported incidents ? in light of the findings , what are the recommendations for future action ?
the aim of this study was to analyze the trends in the volume , rate , nature , management and outcome of adverse incidents reported at one dental teaching hospital over a 6-year period from 2005 to 2010 .
when an adverse incident occurs at kings college london , the first priority of those involved is to make the environment safe and treat any injuries caused by the incident.6 the incident must be reported as soon as it is safe to do so , and within one working day .
any staff or student involved in , witness to , or made aware of an adverse incident has a duty to report it .
if and when an incident occurs , the local manager should be informed at the earliest opportunity . the incident is then required to be documented using the trust s online datixweb form ( http://datix / datix / live / index.php ) . alternatively ,
if the web is unavailable , a paper form should be completed and submitted to the risk management department .
all incidents that have been formally reported at the dental hospital since 2005 have been uploaded onto this standardized trust software , making the collection of data for this research efficient .
incidents being graded by risk managers as red , amber , yellow , or green.6 adverse incidents , or near misses , are to be treated and investigated at a level correspondent with their seriousness , and a formal process is put in place whereby the reporter has two working days to confirm with the risk management department , and the relevant divisional manager ( head of dental nursing ) is ultimately responsible for confirming whether the incident is declared as a serious adverse incident.6
this research set out to answer the following questions :
what are the trends in the reported number and rate of adverse incidents over the last six years?what are the trends in the reported number and rate of adverse incidents , within the calendar year?which procedures are most commonly associated with adverse incidents?what is the context of reported incidents?what is the outcome of reported incidents?in light of the findings , what are the recommendations for future action ?
what are the trends in the reported number and rate of adverse incidents over the last six years ? what are the trends in the reported number and rate of adverse incidents , within the calendar year ? which
procedures are most commonly associated with adverse incidents ? what is the context of reported incidents ?
what is the outcome of reported incidents ? in light of the findings , what are the recommendations for future action ?
the aim of this study was to analyze the trends in the volume , rate , nature , management and outcome of adverse incidents reported at one dental teaching hospital over a 6-year period from 2005 to 2010 .
details of all the incidents that occurred at kings college dental hospital from january 2005 until december 2010 were transported into spss version 17 ( spss inc , chicago , il ) for analysis .
the data included :
incident reference numberincident dategradelocationcategorydescription of incidentaction taken andinvestigation , findings , and reportingclosing date incident reference number description of incident investigation , findings , and reporting categorization of descriptive data on the incident and investigation was carried out manually by examining the description and action of each incident in the records .
one researcher ( ah ) reviewed the descriptive data in the field and created a series of categories based on the nature of the incident .
the findings were discussed and the categories formalized . where an incident could apply to more than one category ,
it was recorded in the more dominant category , as determined by two researchers ( jg and ah ) .
the categorization of incidents was verified by the dental hospital risk manager ( ld ) .
data for the volume of outpatient attendances at the hospital each month from january 2005 to december 2010 were obtained from the dental operations manager , along with the number of cases admitted for day surgery .
this provides a context for the level of possible exposure - prone procedures , albeit that not all outpatient cases involve such procedures , particularly if there is only a dental examination and no dental probe is used .
in total , 287 adverse incidents that resulted in potential exposure of health care workers to body fluids were reported over six calendar years ( 20052010 ) .
it can be observed from the results that the volume of reported incidents peaked in 2007 ( n = 61 ) , with an increase of nearly 50% on the previous year .
the number of incidents reduced again to 51 in 2008 , and reached a plateau at a similar level throughout 2009 and 2010 . the average number of outpatients seen at the dental hospital during the study period ranged between 80,000 and 120,000 per year .
the number of surgical day case admissions almost doubled between 2005 and 2009 , accounting for an average of 9000 admissions per year ( range 610,000 ) .
the overall adverse incident rate for the dental hospital activity ( outpatient appointments and day cases ) over the 6-year period was 3.9 per 10,000 visits .
there was variation by month within the calendar year , with the average number of incidents reported being highest in october and lowest in august ; this trend was most marked during 2007 when activity was highest . although the rate largely parallels the volume of patients seen at the dental hospital , both outpatient and admitted patients combined , calculation of the rate of incidents by month showed that the highest average incidence occurred in october ( 0.056% ) and that the lowest was in august ( 0.020% , table 2 and figure 1 ) . over one fifth ( n = 63 , 22% ) of all incidents that occurred at the hospital between 2005 and 2010 involved local anesthetic needles , making them the most commonly reported cause ( figure 2 ) .
dental drill burs were the second most common cause of injury ( n = 51 , 17.8% ) , followed by dental probes ( n = 27 , 9.4% ) and suture needles ( n = 16 , 5.6% ) .
splash incidents accounted for 19 ( 6.6% ) of the incidents , whilst less common causes involved elevators , scalpels , and scaler tips .
the other sharps category encompasses those incidents that occurred rarely , and includes those involving matrix bands , tweezers , pliers , orthodontic wire , mirrors , midazolam ampoules , denture clasps , and even patients biting the clinician .
nearly three quarters of all the incidents ( n = 208 , 72% ) took place during treatment or whilst clearing away after the appointment .
only 3.5% ( n = 10 ) of incidents occurred before treatment commenced , and 3.8% ( n = 11 ) of the incidents were not clinically related .
the stage at which the incident occurred was not specified in 20% ( n = 58 ) of the cases .
column was completed for 100% of the incidents that occurred . over half ( 54% ,
n = 129 ) of the incidents that occurred during the 6-year study period were graded as green ( unlikely to occur again , very minor , or of no consequence ) whilst 44% ( n = 154 ) were given a
, it appears that an action was reported in 84% ( n = 242 ) of cases ( figure 3 ) .
more than one action was reported in 69% ( n = 168 ) of cases .
the person involved in nearly half ( 48% , n = 140 ) of the incidents bled and washed the injury , 27% ( n = 80 ) applied a dressing / plaster , 32% ( n = 93 ) attended the occupational health department for an assessment , and 3% ( n = 11 ) went straight to the accident and emergency department .
a blood sample was taken from the patient on 26 occasions ; this accounted for 9% of all incidents .
the person involved in the incident was reported in 33% ( n = 94 ) of reported cases .
nine percent ( n = 26 ) of those who identified themselves were dentists and 13% ( n = 37 ) were dental students .
dental nurses accounted for 6% ( n = 18 ) , and student hygienists and therapists accounted for 2% ( n = 7 ) .
one fifth of the total number of incidents reported ( 20.9% , n = 60 ) took place at the primary dental care
department whilst ( 20.6% , n = 59 ) occurred at the dental day case department .
dental day case appointments accounted for 7.9% of total patient attendances at the hospital over the 6-year period .
a further 21.6% ( n = 62 ) were reported to have taken place at the dental school and reported incidents at individual departments , ie , acute dental care , orthodontic clinics , and pediatric clinics .
in total , 287 adverse incidents that resulted in potential exposure of health care workers to body fluids were reported over six calendar years ( 20052010 ) .
it can be observed from the results that the volume of reported incidents peaked in 2007 ( n = 61 ) , with an increase of nearly 50% on the previous year .
the number of incidents reduced again to 51 in 2008 , and reached a plateau at a similar level throughout 2009 and 2010 . the average number of outpatients seen at the dental hospital during the study period ranged between 80,000 and 120,000 per year .
the number of surgical day case admissions almost doubled between 2005 and 2009 , accounting for an average of 9000 admissions per year ( range 610,000 ) .
the overall adverse incident rate for the dental hospital activity ( outpatient appointments and day cases ) over the 6-year period was 3.9 per 10,000 visits .
there was variation by month within the calendar year , with the average number of incidents reported being highest in october and lowest in august ; this trend was most marked during 2007 when activity was highest .
although the rate largely parallels the volume of patients seen at the dental hospital , both outpatient and admitted patients combined , calculation of the rate of incidents by month showed that the highest average incidence occurred in october ( 0.056% ) and that the lowest was in august ( 0.020% , table 2 and figure 1 ) .
over one fifth ( n = 63 , 22% ) of all incidents that occurred at the hospital between 2005 and 2010 involved local anesthetic needles , making them the most commonly reported cause ( figure 2 ) .
dental drill burs were the second most common cause of injury ( n = 51 , 17.8% ) , followed by dental probes ( n = 27 , 9.4% ) and suture needles ( n = 16 , 5.6% ) .
splash incidents accounted for 19 ( 6.6% ) of the incidents , whilst less common causes involved elevators , scalpels , and scaler tips .
the other sharps category encompasses those incidents that occurred rarely , and includes those involving matrix bands , tweezers , pliers , orthodontic wire , mirrors , midazolam ampoules , denture clasps , and even patients biting the clinician .
nearly three quarters of all the incidents ( n = 208 , 72% ) took place during treatment or whilst clearing away after the appointment . only 3.5% ( n = 10 ) of incidents occurred before treatment commenced , and 3.8% ( n = 11 ) of the incidents were not clinically related .
the stage at which the incident occurred was not specified in 20% ( n = 58 ) of the cases .
the grade column was completed for 100% of the incidents that occurred . over half ( 54% ,
n = 129 ) of the incidents that occurred during the 6-year study period were graded as green ( unlikely to occur again , very minor , or of no consequence ) whilst 44% ( n = 154 ) were given a
from the data reported , it appears that an action was reported in 84% ( n = 242 ) of cases ( figure 3 ) .
more than one action was reported in 69% ( n = 168 ) of cases .
the person involved in nearly half ( 48% , n = 140 ) of the incidents bled and washed the injury , 27% ( n = 80 ) applied a dressing / plaster , 32% ( n = 93 ) attended the occupational health department for an assessment , and 3% ( n = 11 ) went straight to the accident and emergency department .
a blood sample was taken from the patient on 26 occasions ; this accounted for 9% of all incidents .
the person involved in the incident was reported in 33% ( n = 94 ) of reported cases . nine percent ( n = 26 ) of those who identified themselves were dentists and 13% ( n = 37 ) were dental students .
dental nurses accounted for 6% ( n = 18 ) , and student hygienists and therapists accounted for 2% ( n = 7 ) .
one fifth of the total number of incidents reported ( 20.9% , n = 60 ) took place at the primary dental care
department whilst ( 20.6% , n = 59 ) occurred at the dental day case department .
dental day case appointments accounted for 7.9% of total patient attendances at the hospital over the 6-year period .
a further 21.6% ( n = 62 ) were reported to have taken place at the dental school and reported incidents at individual departments , ie , acute dental care , orthodontic clinics , and pediatric clinics .
this research suggests that adverse incidents are a feature of dental hospitals and highlights the common sources , all of which are central to the practice of dentistry .
the importance of accurate and consistent reporting of data to ensure that these issues are monitored and inform action in support of reducing risks to staff , students , and patients is underlined .
recording and analyzing adverse incidents is essential to be able to monitor trends and identify areas where training and development may be required .
this paper has highlighted that the consistent reporting and monitoring of events is imperative to re - enforce operator training .
a nigerian study reported that almost 72% of individuals who had been exposed to biological material failed to report the incident.7 there is also evidence from a dental school in brazil that nonreporting of occupational accidents was related to the fact that students considered the exposure to be of minor or low risk or considered the protocol adopted by the institution to be inadequate.8 therefore , we must accept that reported body fluid exposure incidents may only be the tip of the iceberg in dental schools as well as within the nhs generally.9 it may also be assumed that different staff reporting the incident may perceive varying degrees of detail to be satisfactory , thus highlighting the need for more thorough record - keeping criteria .
it should also be noted that the data available on datixweb do not indicate whether the incident has been followed up by the occupational health department . in principle , clinical workers at the hospital have good access to occupational health services , but communication between departments could be strengthened further .
the importance of data recording to assist with learning from incidents and preventing them in future can not be emphasized too much , and should be part of staff induction training at the hospital .
trends are present in the data suggesting that a student presence at the dental hospital influenced a bias towards a higher incidence , with peaks apparent during term time , particularly the autumn .
this could not be validated from the recorded data because the person involved in the incident was not specified in 66% ( n = 191 ) of cases .
nonetheless , the relationship with volume strongly suggests that staff working during the month of august are more experienced , and indeed there are no undergraduate or dental care professional students at that time , so this hypothesis may be justified by the average incident rate during the month of august , being 2.2 per 10,000 compared with the average incident rate of 6.1 per 10,000 during october .
the average incident rate over the six years was 3.9 per 10,000 visits , which is of a similar order of magnitude to a us study of dental schools across the us which reported an average exposure rate of 4.0 per 10,000 patient visits .
past research supports the view that teaching environments have higher incidences of occupational exposures than nonteaching environments.3,8,1012 the peak in 2007 could be associated with additional students providing care on site , following an expansion of student numbers .
past research highlights the importance of introducing safe practices and guidance.12 a drive to reduce the rate of incidents led to the improvement of induction and training for year 3 students in 2008 .
a 100% no resheathing policy was introduced in august 2008 in line with recommendations from the uk department of health , whilst instruction was given in safe disposal of dental needles in sharps bins following single use , which consequently may have been responsible for the reduction and plateau of incidents .
this issue is particularly important in dental teaching hospitals where there are responsibilities for staff , students , and patients .
the occurrence of an adverse incident was most frequently reported in association with the administration of local anesthetic and a dental bur , followed by incidents involving probes and suture needles . in reviewing reports from various dental schools
, it appears that the same trend is common,10,13 and that junior students appear to be more at risk than students in final year.11 a policy at the trust does indicate that the clinician should dispose of his / her own sharp instruments immediately after surgery in the sharps containers which have been installed in each cubicle / operating room .
the figures suggest that further training is needed in these areas , with particular regard to the administration of anesthetic .
unfortunately , lack of detail about who was involved in each incident makes it difficult to specify who should be targeted for further training .
forty - four percent had no recorded consequence and 2% of the incidents had moderate consequences .
this does not reflect the availability of support in occupational health services to support health care personnel in this hospital , but may be a reflection of the low severity of the incidents .
nonetheless , this analysis highlights the need for incidents to be taken seriously , fully recorded , and followed up .
further research in this area should involve monitoring and reporting of blood samples of staff and patients .
all incidents that occurred during the 6-year period were graded according to their risk at the time of reporting ; however , it became apparent during examination of the data that the descriptions of each incident varied significantly in detail due to reporter variation .
this made categorization challenging , so it could be proposed that training for incident reporting should be put into practice .
the clinical workforce at the dental hospital has full access to the occupational health department at all times , and it was reported that over a third of those suffering an incident attended the department .
occupational health records can not be accessed via the datixweb system , which is a clear barrier to consistent follow - up .
this research suggests that adverse incidents are a feature of dental hospitals , highlighting the importance of accurate and consistent reporting of data to ensure that these issues are monitored and addressed in support of staff , students and patients .
aspects of clinical practice and groups of health care workers that would benefit from action to protect staff and indirectly the health of their patients are identified .
Output:
| background : the safety and protection of patients and health care workers is of paramount importance in dentistry , and this includes students in training who provide clinical care . given the nature of dental care , adverse incidents can and do occur , exposing health care workers to body fluids and putting them at risk of infection , including contracting a blood - borne virus .
the aim of this research was to analyze trends in the volume , rate , nature , management , and outcome of adverse incidents reported at one dental teaching hospital from 2005 to 2010.methods:descriptive analysis of trends in the volume , rate , nature , management , and outcome of adverse incidents reported at one dental teaching hospital over a six - year period was undertaken in relation to the level of outpatient and day surgery activity.results:in total , 287 incidents were reported over a six - year period , which amounted to 0.039% of outpatient or day surgery appointments .
nearly three quarters of all the incidents ( n = 208 , 72% ) took place during treatment or whilst clearing away after the appointment .
the most frequent incidents were associated with administration of local anesthetic ( n = 63 , 22% ) , followed by burs used in dental hand pieces ( n = 51 , 18%).conclusion : this research confirms that adverse incidents are a feature of dental hospitals and reports the common sources .
the importance of accurate and consistent reporting of data to ensure that these issues are monitored to inform action and reduce risks to staff , students , and patients are highlighted . |
PubmedSumm118697 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: most lung cancers are asymptomatic ; therefore , the majority of patients are diagnosed with late - stage disease , which restricts treatment options , with the exception of chemotherapy .
however , the identification of egfr mutations and the introduction of epithelial growth factor receptor tyrosine kinase inhibitors ( egfr - tkis ) have expanded treatment options and improved results . on average ,
acquired drug resistance to erlotinib and gefitinib , 1st - generation egfr - tkis , has been observed between 8 and 16 months of use.1 ) afatinib , a 2nd - generation egfr - tki , is expected to overcome the acquired resistance that develops with 1st - generation egfr - tkis by irreversibly blocking not only egfr but also human epidermal growth factor receptor 2 ( her2 ) dimer formation .
currently , there is an ongoing comparative study investigating the efficacy of 1st- and 2nd - generation egfr - tkis in lung cancer .
in addition to erlotinib and gefitinib , afatinib has been reported to be responsible for drug - induced pneumonitis as a common adverse effect in clinical trials.23 ) several preclinical studies have reported acute drug - induced pneumonitis after erlotinib and gefitinib use , whereas there have been no reports of the same fatal adverse effects with afatinib . in the present case , we emphasize the need for caution with afatinib use as it may result in fatal pulmonary complications .
a 78-year - old woman was admitted for dry cough and weight loss via our outpatient clinic on 8 august 2015 .
she had been undergoing medical treatment for diabetes , dyslipidemia , and osteoporosis since 20 years .
she was diagnosed with metastatic lung adenocarcinoma ( t1b n0 m1a , stage iv ) with egfr mutations on the basis of the findings obtained with chest computed tomography ( ct ) , positive emission tomography - ct , percutaneous transthoracic needle aspiration ( pcna ) of the left superior lobe , and wedge resection of the right superior lobe ( figures 1 , 2 ) .
the biopsy results from the pcna results were obtained on august 22nd and the wedge resection results were obtained on august 28th .
afatinib treatment ( 40 mg / d ) was initiated on 2 september 2015 ; no specific complications were observed during afatinib use and the patient was discharged .
she was re - admitted for acute dyspnea on 7 september 2015 via the outpatient clinic ; she had been consuming afatinib daily for 6 days .
the patient 's initial vital signs were as follows : blood pressure , 110/70 mm hg ; heart rate , 100 beats / min ; respiratory rate , 20 breaths / min ; body temperature , 37.7 ; and oxygen saturation , 63% as room air .
on auscultation , coarse breathing sounds and crackles were heard over both the lungs fields .
initial laboratory test results were as follows : total leukocyte count , 10,300/mm ; hemoglobin , 9.6 g / dl ; platelet count , 217,000/mm ; c - reactive protein , 18.66 mg / dl ; and d - dimer , 1.78 mg fibrinogen equivalent units / ml . all other parameters were within their respective normal limits .
a chest ct was conducted on the suspicion of pulmonary thromboembolism and drug - induced pneumonitis .
it showed that there were new consolidations and ground glass opacity shadows , whereas the size of lung cancer itself had decreased .
this diagnosis was based on the following : the onset of symptoms after drug application , the absence of another explanatory cause for the hypoxia , the results of the chest ct , and the negative results of the nasal swab and sputum study tests for pneumocystis pneumonia and viral pneumonia , which are frequently found in immune - depressed patients .
we planned to perform bronchoalveolar lavage , a transbronchial lung biopsy , and pcna to exclude other infectious causes and confirm the diagnosis of acute drug - induced pneumonitis .
however , the patient refused to undergo the invasive procedures . despite the intensive care provided , which included oxygen therapy via a high - flow nasal cannula , steroid pulse therapy ( methylprednisolone , 500 mg daily for 3 days ) , and broad spectrum antibiotics
lung cancer is a major cause of malignancy - associated mortality worldwide , and the 5-year survival rate is as low as 15% . widely recognized risk factors of lung cancer include direct or indirect smoking , radon gas , and asbestos .
there is no specific treatment because most lung cancer patients are diagnosed with late stage disease . until egfr - tkis were introduced , intravenous chemotherapy was the only treatment option and the average survival time was less than 12 months .
the discovery of egfr mutations and the introduction of oral egfr - tki agents expanded the treatment options .
this mutation is more prevalent in young women , asian people , and non - smokers .
when this system is blocked by egfr - tkis , the lung cancer cells can not proliferate and they undergo apoptosis .
erlotinib and gefitinib , 1st - generation egfr - tkis , reversibly bind to egfr , preventing its dimerization .
most lung cancers with egfr mutations develop resistance to the 1st - generation egfr - tkis within , on average , 8 to 16 months of use .
the most common acquired resistance is a t790 m missense mutation in exon 20 , which is reported in 50% to 60% of advanced stage patients after 1st - generation egfr - tki use .
afatinib , a 2nd - generation egfr - tki , is expected to overcome the acquired resistance that develops after 1st - generation egfr - tki use , by irreversibly blocking , not only egfr , but also her2 dimerization .
currently , there is an ongoing comparative study of 1st- and 2nd - generation egfr - tkis with regard to treatment efficacy in lung cancer.23 ) common complications associated with afatinib use include gastrointestinal and dermatologic complications such as diarrhea , vomiting , fatigue , loss of appetite , and skin rash .
in addition , drug - induced pneumonitis has been reported , albeit not as frequently as with 1st - generation egfr - tki use.23 ) acute fatal drug - induced pneumonitis was reported in several preclinical studies after treatment with erlotinib and gefitinib , and a number of meta - analyses and literature studies of drug - induced pneumonitis , including acute fatal drug - induced pneumonitis , have been conducted.45678 ) contrary to the erlotinib and gefitinib results , drug - induced pneumonitis , a common complication of egfr - tki use , had been rarely reported with afatinib use .
acute fatal pneumonitis after afatinib use , as in the current study , has been reported in only 1 previous study.9 ) it is yet unknown how drug - induced pneumonitis occurs after 1st - generation egfr - tki use . on the basis of the results of previous studies ,
we have identified a possible mechanistic link between the 1st - generation egfr - tki gefitinib use and drug - induced pneumonitis.910 ) as we mentioned above , egfr - tkis block egfr phosphorylation , thus preventing injured epithelium from regenerating and proliferating.9 ) in addition , when an acute lung injury occurs , expression is upregulated in order to promote regeneration of the damaged epithelium .
in other words , egfr - tkis interrupt this damage - repair mechanism of egfr , and if these interruptions accumulate , fatal drug - induced pneumonitis may result.10 ) this mechanism was identified based on gefitinib , not afatinib , use . however , afatinib and gefitinib share common characteristics , such as egfr - blocking functions , so we assume that this potential mechanism could also apply to afatinib
. we could not identify a specific and effective treatment for egfr - tki - induced pneumonitis .
we found only 2 cases of gefitinib - induced pneumonitis that were cured by drug cessation , high dose steroids , and mechanical ventilation.45 ) these treatments were identical to those administered for general drug - induced pneumonitis .
further studies should be performed to identify the exact mechanism of , and treatment for , afatinib - induced pneumonitis . in summary , in the treatment of metastatic lung adenocarcinoma , 2nd - generation egfr - tkis are expected to overcome the acquired resistance which occurs after 1st - generation egfr - tki use .
an ongoing comparative study is evaluating the treatment efficacy of 1st- and 2nd - generation egfr - tkis in lung cancer .
various target treatment agents , including egfr - tkis such as afatinib , have been developed and are now widely used ; consequently , treatment efficacy has improved and chemotherapy is no longer the only treatment option .
however , the incidence of various complications , including pulmonary toxicity , which are not widely researched , will inevitably increase .
therefore , based on the results in this case report , clinicians should be aware of the potential for afatinib treatment - associated complications .
Output:
| afatinib is an oral tyrosine kinase inhibitor ( tki ) that inhibit endothelial growth factor receptor ( egfr ) , human epidermal growth factor receptor 2 ( her2 ) , and her4 .
the common side effects of egfr tki are rash , acne , diarrhea , stomatitis , pruritus , nausea , and loss of appetite .
drug induced pneumonitis is the less common adverse effects of egfr tki .
afatinib , 2nd generation egfr tki is anticipated to overcome drug resistance from 1st generation egfr tki according to preclinical study , and several studies are being conducted to compare clinical efficacy between 1st and 2nd egfr tki .
several cases of rug induced acute fatal pneumonitis were reported after use of erlotinib or gefitinib . however , a case of acute fatal pneumonitis associated with afatinib was note reported except drug induced pneumonitis in other clinical study . here ,
we present a cases of acute severe pneumonitis related with afatinib in metastatic lung adenocarcinoma with literature review . |
PubmedSumm118698 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: diabetes mellitus ( dm ) is reaching an alarming proportion worldwide , as is known that dm has a complex multifactorial pathogenesis .
the devastating complications of diabetes are the macro- and microvascular diseases [ 1 , 2 ] . of them , diabetic retinopathy ( dr ) is the most common microvascular complication and is a leading cause of blindness across the globe . to date , many environmental and clinical factors have been proposed to confer risk of dr development , such as prolonged duration of diabetes , alteration of glucose metabolism , and poor glycemic control .
additionally , genetic predisposition , independent of the above - mentioned factors , has been found to contribute to dr pathology ; the evidence comes from the observation of disease aggregation among family members and multiple dr - associated genes identifications [ 57 ] .
so far , the exact pathogenesis of dr is still unclear and is known to be involved in several physiopathologic pathways , such as angiogenesis factors , oxidative stress , apoptosis , and protein kinase c ( pkc ) [ 810 ] .
more recent evidence depicting dr as a retinal disease associated with inflammation has drawn special attention and garnered great research interests [ 1113 ] .
complement system is an important component of innate immunity and involved in the modulation of several immune and inflammatory responses .
the complement system can be divided into classical , lectin , and alternative pathway ; activation of the system is tightly regulated by complement factors ; disruption of complement regulation can lead to several distinct downstream inflammatory actions en route to the pathogenesis of dr [ 14 , 15 ] .
evidence for the link comes from the observation of increased expression of several complement factors in dr patients ; these factors included c1 inhibitor ( c1inh , also known as serpin peptidase inhibitor , clade g , serping1 ) , c5 , factor h ( cfh ) , and factor b ( cfb ) [ 16 , 17 ] . in our previous studies , genetic variants in the cfh and cfb genes , both involved in complement alternative pathway , have been evaluated and identified as susceptibility genes for dr .
moreover , cfh and cfb , as well as other complement pathway genes , have also been found to be associated with a range of inflammatory diseases .
therefore , a genetic study focused on other complement genes was designed with a view to elucidating the involvement of complement system in dr development .
two complement genes , serping1 and c5 , involved in the classical pathway and in the central part of complement cascade , respectively , were selected for evaluation .
furthermore , stratification by dr stage and genotype - phenotype correlation analysis were also performed to identify these factors associated with prognosis and clinical features .
the study protocol was approved by the ethics committee on human research , harbin medical university .
the study procedures were conducted in accordance with the tenets of the declaration of helsinki . written informed consent
all study subjects were han chinese recruited from the first affiliated hospital of harbin medical university .
all patients received complete ophthalmic examinations and clinical information collection , including corrected visual acuity , slit - lamp biomicroscopy , fundoscopic examination , age , gender , progression time from diabetes to dr , body mass index ( bmi ) , hba1c level , smoking status , and presence of hypertension and hyperlipidemia , as well as insulin application .
the study involved 570 unrelated individuals with type 2 diabetes mellitus ( t2 dm ) ; patients with type 1 diabetes , gestational diabetes , or maturity - onset diabetes were excluded from the study .
the diagnosis of t2 dm was based on world health organization criteria . of the group ,
295 patients were diagnosed with dr ( 156 [ 52.9% ] pdr and 139 [ 47.1% ] npdr ) ; 275 subjects without dr but with type 2 diabetes duration of more than 10 years were considered as dm controls . the stage of dr was determined according to the early treatment diabetic retinopathy study ( etdrs ) criteria .
people with any systemic inflammation diseases , or any other ocular disorders such as age - related macular degeneration ( amd ) , glaucoma , or retinal venous occlusion , were also excluded .
we adopted a haplotype - tagging snp approach and obtained the tagging snps across the targeted regions , from the international hapmap project for the chinese han beijing ( chb ) population ( http://hapmap.ncbi.nlm.nih.gov/ , hapmap genome browser ) .
two snps ( rs1005511 and rs3824988 ) from serping1 and six from c5 ( rs12237774 , rs2269066 , rs17611 , rs1548782 , rs10985126 , and rs1017119 ) were selected by the tagger - pairwise method with r and maf ( minor allele frequency ) values greater than 0.8 and 0.10 , respectively .
genomic dna was extracted from whole blood using a qiaamp blood kit ( qiagen , hilden , germany ) according to the protocol .
all the snps were genotyped by taqman snp genotyping assays ( applied biosystems inc . , foster city , ca ) in the lightcycler 480 real - time pcr system ( roche , switzerland ) according to the manufacturer 's instructions .
hardy - weinberg equilibrium ( hwe ) of individual snp was tested by test .
allelic and genotypic association of each snp was calculated by using test or fisher exact test .
dominant and recessive models were also applied to investigate the disease association with regard to the minor allele .
the odds ratios ( or ) and 95% confidence intervals ( ci ) were calculated .
( ld , d ) between polymorphisms and expectation - maximization- ( em- ) based haplotype association analysis were assessed using the haploview software .
student 's t - test and test were used to compare continuous clinical data and categorical variables , respectively .
p values were corrected by bonferroni test ( n = total number of snps ) or permutation test in haploview software .
in our study , a total number of 570 unrelated individuals with t2 dm were recruited , comprising 295 dr patients and 275 dm controls .
since we aimed to recruit t2 dm patients without dr as controls , the mean duration of disease was longer than that of the dr group so as to largely rule out late - onset dr ( p < 0.01 ) .
the proportions of hyperlipidemia and insulin application were higher in dr group than that in dm controls ( p = 0.042 and p < 0.001 , resp . ) .
no significant differences in other clinical features were observed between two groups ( table 1 ) .
two haplotype - tagging snps in serping1 and six haplotype - tagging snps in c5 were selected , which capture over 90% of all alleles across their corresponding locus with a maf larger than 0.10 and a mean r of 0.80 in the hapmap chinese han population .
the genotype frequencies of the eight selected snps followed the hwe in all subjects . for c5-rs17611
, there was an obvious trend towards lower proportions of g allele and gg homozygosity in dr patients than dm controls ( p = 0.056 , or = 0.79 , 95% ci = 0.621.0 ; p = 0.009 , pcorr = 0.072 , or = 0.53 , 95% ci = 0.330.86 , resp . ) , but the associations either were marginal or could not remain after adjustment for multiple testing .
for other snps , no significant associations were detected with dr in any genetic models ( table 2 ) . among the 295 dr patients , 139 ( 47.1% ) were npdr and 156 ( 52.9% ) were pdr ; stratification analysis by the dr stage was performed . in pdr patients , significant lower frequencies of g allele and gg homozygosity for c5-rs17611 were found compared to that in dm group even after multiple testing correction ( pcorr = 0.032 , or = 0.65 , 95% ci = 0.480.87 ; pcorr = 0.016 , or = 0.37 ,
95% ci = 0.190.71 , resp . ) , implying a protective effect ; such difference was not observed in npdr patients ( table 3 ) . for other snps ,
no significant differences in the allelic or genotypic frequencies were found in either npdr or pdr subtypes compared with dm controls .
pairwise ld analysis showed that two serping1 tagging snps were included in one haplotype block in npdr , pdr , and total dr patients .
no haplotype was significantly associated with any group ( all p > 0.1 , table 4 ) .
regarding c5 , ld analysis revealed one haplotype block in three groups including snps rs17611 ( the most significant finding ) and rs1548782 ( figure 1 ) .
the haplotype aa , defined by the two snps , showed a significant risk for pdr patients ( p = 0.004 , permutation p = 0.023 ; or = 1.54 , 95% ci = 1.152.06 ) .
no significant haplotype association was detected among the other two comparisons ( table 5 ) . considering the significance of c5-rs17611 in this study ,
the results showed that dr patients carrying protective rs17611 gg genotype would present a delayed progression from dm to dr onset compared with patient carrying aa genotype ( 9.3 6.4 versus 7.0 5.5 , p = 0.045 ; figure 2 ) ; no significant difference for other clinical features was detected among different genotype carriers .
in this study , we performed a haplotype - tagging snp analysis of two complement pathway genes , serping1 and c5 , in t2 dm and dr patients .
our results demonstrated that c5-rs17611 was significantly associated with dr , particularly conferred to the pdr susceptibility ; this functional variant also linked with certain clinical significance . moreover ,
in contrast , none of the snps in serping1 were significantly associated with dr and its subtypes .
these findings together suggest that serping1 is not a disease gene for dr , but c5 is likely to be a susceptibility gene for dr in chinese patients . to our knowledge , this is the first genetic study to investigate serping1 and c5 genes in dr patients . over the past decade
, great achievements have been made in elucidating the genetic background of the disease ; so far , more than 30 dr - associated genes involved in different metabolic mechanisms and functional pathways have been reported [ 22 , 23 ] .
our previous study has successfully identified two complement alternative pathway genes , cfh and cfb , which were associated with dr development .
results of this study enrich our knowledge of the genetic architecture of dr and the involvement of each complement pathway in dr pathogenesis .
in addition , we also found that the proportions of insulin application were higher in dr group than that in dm controls ; it was supposed that these dm patients without complications have a relatively good metabolic control , which may explain the lower frequency of individuals with insulin therapy .
as described above , the complement system is a key component of innate immunity , consisting of a large family of membrane - bound proteins that are critical for protection against bacterial infection and immune complex deposition .
c5 , being the first of many components of the terminal pathway , mediates many potent inflammatory events and plays a major role in the complement system . in the cascade ,
a critical event is the cleavage of c5 into fragments of c5a and c5b , as well as the subsequent formation of mac ( c5b-9 ) which is involved in cytolysis , cell activation , and production of inflammatory mediators . in vitro study
has revealed that c5a treatment induced increased production of several inflammatory cytokines , such as mcp-1 , il-6 , il-8 , and vegf , from retinal pigment epithelial cells [ 25 , 26 ] . in clinical study , c5b-9 deposition was detected on the endothelial surface of retinal vessels in eye donors with diabetes ; vitreous concentration of c5a increased significantly in pdr patients compared with controls [ 14 , 27 ] .
furthermore , c5 gene has been found to affect susceptibility to several inflammatory conditions , including amd , rheumatoid arthritis , and renal allograft outcomes [ 2830 ] . in the present study , c5-rs17611
was found to be associated with pdr patients ; meanwhile , rs17611 was also found to be associated with periodontitis and the gg genotype was linked with increased c5 levels in patients with rheumatoid arthritis [ 29 , 31 ] .
the change of rs17611 a > g nucleotide results in the synthesis of valine instead of isoleucine ; a functional analysis on rs17611 showed that individuals homozygously expressing the risk s17611 allele exhibit increased c5a and decreased c5 in plasma , evidence of increased c5 turnover ; this structural change might alter the rate of c5 cleavage and explain its association with inflammatory diseases .
component 1 inhibitor gene ( serping1 ) encoding c1inh is a key regulator in classic and lectin complement pathway and involved in the development of several immune - related diseases .
in addition , c1inh was also found to be expressed in both retinal and retinal pigment epithelium ( rpe ) layers [ 3234 ] .
but , in our study , no association between serping1 polymorphisms and dr was found , even stratified by dr stage or considered clinical features .
the results suggested that serping1 , and the gene - involved classical pathway , might not contribute significantly to the risk of dr .
further studies to determine the biologic roles of these polymorphisms and the haplotype in dr are still warranted ; additionally , it would be better to include healthy controls in this study to fully reflect the disease association . in summary
, this study first demonstrated that c5 rs17611 is a susceptibility locus for dr and particularly predisposes to pdr subtype with clinical significance .
the complement classical pathway gene , serping1 , may confer no or limited risk for dr development . together with our previous findings ,
our results help to further enrich the growing understanding of genetic spectrum of dr and clarify the involvement of each complement pathway in dr pathogenesis from molecular perspectives .
Output:
| diabetic retinopathy ( dr ) has complex multifactorial pathogenesis .
this study aimed to investigate the association of complement pathway genes with susceptibility to dr .
eight haplotype - tagging snps of serping1 and c5 were genotyped in 570 subjects with type 2 diabetes : 295 dr patients ( 138 nonproliferative dr [ npdr ] and 157 proliferative dr [ pdr ] ) and 275 diabetic controls . among the six c5 snps
, a marginal association was first detected between rs17611 and total dr patients ( p = 0.009 , or = 0.53 for recessive model ) . in stratification analysis , a significant decrease in the frequencies of g allele and gg homozygosity for rs17611 was observed in pdr patients compared with diabetic controls ( pcorr = 0.032 , or = 0.65 and pcorr = 0.016 , or = 0.37 , resp . ) ; it was linked with a disease progression .
a haplotype aa defined by the major alleles of rs17611 and rs1548782 was significantly predisposed to pdr with increased risk of 1.54 ( pcorr = 0.023 ) .
regarding other variants in c5 and serping1 , none of the tagging snps had a significant association with dr and its subgroups ( all p > 0.05 ) .
our study revealed an association between dr and c5 polymorphisms with clinical significance , whereas serping1 is not a major genetic component of dr .
our data suggest a link of complement pathway with dr pathogenesis . |
PubmedSumm118699 | ***TASK***
the task is to summarize an input biomedical literature in six sentences
***INPUT***
the input is a biomedical literature
***OUTPUT***
the output is the summary of an input biomedical literature in six sentences
***DOCUMENTATION***
***EXAMPLES***
Input: to report the successful outcome of a rare optic pit - associated maculopathy with an outer retinal hole following 23 g vitrectomy , internal limiting membrane ( ilm ) peeling and fluid - gas exchange without additional endolaser .
this case report documents a 56-year - old male patient with complaints of progressive diminution of vision in the right eye more than in the left eye due to an optic disc pit with an outer retinal hole and a cataract .
the case report shows the successful outcome of a rare optic pit - associated maculopathy with an outer retinal hole and a cataract following phacoemulsification with 23 g vitrectomy , ilm peeling and fluid - gas exchange without additional endolaser .
optic pits occur equally between men and women . they are seen in roughly 1 in 10,000 eyes , and approximately 85% of optic pits
optic pits have been associated with serous retinal detachments [ 3 , 4 ] in up to as many as 50% of all cases .
imamura et al . reported an outer layer hole in only 27% of eyes with retinal detachment associated with optic disc maculopathy .
the detachments associated with optic pits may occur at any age but most frequently present in early adulthood .
the most popular theory behind this association is a separation of the layers of the retina , known as retinoschisis , due to fluid ( the vitreous humor ) entering the optic pit and traveling between the inner and outer layers of the retina .
we hereby present a case report showing successful management of a rare optic disc pit anomaly with an outer retinal hole and a cataract , which was treated with phacoemulsification vitrectomy with gas tamponade but without endolaser .
marked improvement in visual acuity corresponded to the resolution of the outer retinal hole observed clinically as well as on optical coherence tomography ( oct ) .
a 56-year - old male presented with a 6-month history of painless , progressive diminution of vision in the right eye more than in the left eye .
his past medical history and ocular history were not significant , and there was no history of trauma or surgery .
ophthalmic examination showed the best - corrected visual acuity of counting fingers 2 meters in the right eye and 20/40 in the left eye .
on anterior segment examination , both pupils reacted normally to light , whereas slit - lamp biomicroscopy revealed grade ii nuclear sclerosis in both eyes
dilated fundus examination of the right eye revealed an oval , gray - yellow crater - like depression on the temporal aspect of the optic disc , suggestive of an optic pit ( fig .
1 ) . in the macular area adjoining the disc there was a serous elevation of around 4 disc diameters with central thinning of the retinal layers , giving the impression of an outer retinal hole .
oct was done and confirmed the presence of an optic pit with maculopathy and an outer retinal hole ( fig .
2 ) . fundus fluorescein angiography showed a window defect corresponding to the outer retinal hole in addition to pooling of the dye in the late venous phase , suggestive of serous retinal detachment ( fig .
3 ) . pros and cons of various treatment options including no treatment were discussed . after obtaining informed consent ,
the patient underwent phacoemulsification with intraocular lens implantation with 23 g pars plana vitrectomy with sf6 gas tamponade without additional endolaser .
the vitreous was stained with triamcinolone 0.1 ml , and the induction of posterior vitreous detachment was achieved with the vitreous cutter . after completing the vitrectomy , internal limiting membrane ( ilm ) peeling
the patient was instructed to maintain a face - down position for 1 week and was followed up closely .
after 2 weeks , the gas bubble was completely absorbed , and vision had improved to 20/60 .
the oct showed no evidence of serous retinal detachment or retinoschisis , and the outer retinal break was sealed ( fig .
the patient was followed up for the next 2 years on a regular basis and there was no evidence of recurrence .
this case report documents the successful outcome of a rare optic pit - associated maculopathy with an outer retinal hole and a cataract following phacoemulsification 23 g vitrectomy , ilm peeling and fluid - gas exchange without additional endolaser .
imamura et al . reported an outer layer hole in only 27% of eyes with retinal detachment associated with optic disc maculopathy .
however , a relatively high incidence of recurrence has been reported after laser treatment alone ; laser treatment also results in temporal scotoma to the patient .
hirakata et al . reported the success of vitrectomy with induction of posterior vitreous detachment and gas tamponade , without additional laser treatment in reattaching the macula , and improvement in central vision in most patients with optic disc pit maculopathy . in our patient ,
his visual acuity remained at 20/60 at the end of 2 years of follow - up .
the limited recovery in visual function is probably related to the longstanding nature of the condition .
vitrectomy with ilm peeling and gas tamponade without any additional laser photocoagulation may be sufficient for the treatment of optic disc pit maculopathy even with an outer retinal hole .
although further studies are required to evaluate the above findings , documenting large series is challenging due to the rarity of cases with optic disc maculopathy with outer retinal holes .
none of the authors has a financial or proprietary interest in any material or method mentioned .
Output:
| objectiveto report the successful outcome of a rare optic pit - associated maculopathy with an outer retinal hole following 23 g vitrectomy , internal limiting membrane ( ilm ) peeling and fluid - gas exchange without additional endolaser.methodinterventional case report.resultsthis case report documents a 56-year - old male patient with complaints of progressive diminution of vision in the right eye more than in the left eye due to an optic disc pit with an outer retinal hole and a cataract .
optical coherence tomography confirmed the presence of an outer retinal hole .
the case report shows the successful outcome of a rare optic pit - associated maculopathy with an outer retinal hole and a cataract following phacoemulsification with 23 g vitrectomy , ilm peeling and fluid - gas exchange without additional endolaser . |
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