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Percutaneous laser disc decompression.
Choy, D S
Herniated disc disease has an incidence of 1.7% in the U.S. Heretofore, open operative procedures were the rule for this condition when conservative measures were ineffective. Choy and Ascher introduced this new technique in February 1986 using a Nd:YAG laser introduced into the disc through an optical fiber in a needle. Percutaneous laser disc decompression is based on the principle that in an enclosed hydraulic space, such as an intact disc, a small reduction in volume is associated with a disproportionate fall in pressure. In the disc, this partial vacuum causes the herniated portion to move away from the nerve root back toward the center of the disc. This technique has been taught worldwide and is being performed in most of Europe, Japan, the United States, and Korea. In this special issue devoted to percutaneous laser disc decompression (PLDD), we will set forth the basic science of PLDD, patient selection, use of the holmium:YAG, and the Nd:YAG lasers, operative technique, and results. PMID:10150634
Percutaneous diode laser disc nucleoplasty
NASA Astrophysics Data System (ADS)
Menchetti, P. P.; Longo, Leonardo
The treatment of herniated disc disease (HNP) over the years involved different miniinvasive surgical options. The classical microsurgical approach has been substituted over the years both by endoscopic approach in which is possible to practice via endoscopy a laser thermo-discoplasty, both by percutaneous laser disc nucleoplasty. In the last ten years, the percutaneous laser disc nucleoplasty have been done worldwide in more than 40000 cases of HNP. Because water is the major component of the intervertebral disc, and in HNP pain is caused by the disc protrusion pressing against the nerve root, a 980 nm Diode laser introduced via a 22G needle under X-ray guidance and local anesthesia, vaporizes a small amount of nucleous polposus with a disc shrinkage and a relief of pressure on nerve root. Most patients get off the table pain free and are back to work in 5 to 7 days. Material and method: to date, 130 patients (155 cases) suffering for relevant symptoms therapy-resistant 6 months on average before consulting our department, have been treated. Eightyfour (72%) males and 46 (28%) females had a percutaneous laser disc nucleoplasty. The average age of patients operated was 48 years (22 - 69). The level of disc removal was L3/L4 in 12 cases, L4/L5 in 87 cases and L5/S1 in 56 cases. Two different levels were treated at the same time in 25 patients. Results: the success rate at a minimum follow-up of 6 months was 88% with a complication rate of 0.5%.
Radiological considerations: percutaneous laser disc decompression.
Botsford, J A
Diagnostic radiology is an integral part of percutaneous laser disc decompression (PLDD). All physicians involved in PLDD patient selection and treatment must be familiar with the imaging techniques unique to this procedure to ensure a successful outcome. The following review is based on the cumulative experience gained in performing over 150 PLDD procedures. It discusses the function of diagnostic radiology in all facets of PLDD including patient selection, intraoperative imaging, postoperative evaluation, and analysis of complications. Fundamental radiologic concepts that apply to PLDD are explained and protocols suggested to optimize results and avoid complications. PMID:10146513
Percutaneous laser disc decompression with the holmium: YAG laser.
Casper, G D; Hartman, V L; Mullins, L L
This article discusses the evolution of the percutaneous laser disc decompression (PLDD) method using a holmium:YAG laser. Advantages of using this wavelength and several techniques for its use in PLDD are reviewed. The article also discusses the current devices and delivery systems available for this application. PMID:10150646
Changes in disc herniation after CT-guided Percutaneous Laser Disc Decompression (PLDD): MR findings
NASA Astrophysics Data System (ADS)
Brat, Hugues G.; Bouziane, Tarik; Lambert, Jean; Divano, Luisa
The aim of Percutaneous Laser Disc Decompression (PLDD) is to vaporize a small portion of the nucleus pulposus. Clinical efficacy of this technique is largely proven. However, time-evolution of intervertebral disc and its hernia after PLDD is not known. This study analyses changes in disc herniation and its native intervertebral disc at a mean follow-up of 7.5 months after PLDD in asymptomatic patients. Main observations at MRI are appearance of a high signal on T2WI in the hernia in 59%, shrinking of the hernia in 66% and overall stability of disc height.
The effectiveness of percutaneous laser disc decompression for the prolapsed lumbar intervertebral disc
NASA Astrophysics Data System (ADS)
Mu, Ming Wei; Liu, Wei; Feng, Wei; Ma, Nan
Objective: to investigate the role of associated factors in the effectiveness of laser treatment for prolapsed lumber intervertebral disc. Method: 302 prolapsed lumber intervertebral discs in 212 patients were treated with percutaneous laser disc decompression (PLDD). Patients were followed up by 12month, the associated factors which affecting the effectiveness of treatment, ie age, duration of illness were analyzed. Results: Punctual Success rate was 100%. After 12 month's follow up, 86% successful outcomes were obtained, in which 93% successful outcomes were obtained in patients less than 50 years old, 92% successful outcomes was obtained in the patients whose duration of illness less than 1 year.
The role of radiology in percutaneous laser disc decompression.
Botsford, J A
Diagnostic imaging has always played a key role in the evaluation of patients with suspected lumbar disc herniation. With the development of percutaneous laser disc decompression (PLDD), radiology is now equally important in its treatment. All physicians involved with the PLDD candidate must be familiar with the imaging techniques unique to this procedure to ensure a successful outcome. The following review is based on the cumulative experience gained in performing over 200 PLDD procedures. It discusses the function of diagnostic radiology in all facets of PLDD including patient selection, intraoperative imaging, postoperative evaluation, and analysis of complications. Fundamental radiologic concepts that apply to PLDD are explained and protocols suggested to optimize results and avoid complications. PMID:10150644
Percutaneous laser disc decompression: an update--Spring 1992.
Choy, D S; Michelsen, J; Getrajdman, G; Diwan, S
Percutaneous laser disc decompression (PLDD) is being performed in multiple centers in the United States, Germany, Austria, France, and Switzerland with the Nd:YAG having the longest follow up at more than 75 months. The experience with this procedure, in both humans and animals, carried out over the past decade is presented along with a detailed discussion of the surgical procedure. Conditions that favor such surgery and contraindications to the procedure are also presented. There are a number of important advantages to PLDD that make it a procedure that merits continued investigation. Because PLDD is relatively noninvasive, it can be repeated. Because there is no cutting, there is no perispinal scar formation, with possible future pain secondary to entrapment of nerves by scar. Because of its effectiveness for treatment, the laser, in this application, should prove to be an important addition to the spinal surgeon's armamentarium. PMID:10147861
Efficacy of percutaneous laser disc decompression on lumbar spinal stenosis.
Ren, Longxi; Han, Zhengfeng; Zhang, Jianhua; Zhang, Tongtong; Yin, Jian; Liang, Xibin; Guo, Han; Zeng, Yanjun
The objective of this study is to observe the effect of percutaneous laser disc decompression (PLDD) on lumbar spinal stenosis (LSS). Thirty-two LSS patients were treated using pulsed Nd: YAG laser, of which 21 cases (11 males and 10 females with an average age of 64 years old) were followed up for 2 years. All of the 21 patients had intermittent claudication with negative straight leg raising test results. Fifteen patients suffered from anterior central disc herniation which often compressed the cauda equina but seldom compressed the posterior part; six patients suffered from posterior ligamentum flavum hypertrophy which often compressed the cauda equina but seldom compressed the anterior part. The efficacy was evaluated 1, 3, 6, 12 and 24 months after surgery on 21 patients using the performance evaluation criteria of the lumbago treatment by the Japanese Orthopaedic Association (JOA 29 scores). The fineness (i.e. excellent and good treatment outcome) rate 1, 3, 6, 12 and 24 months after the operation were 46.7%, 66.7%, 66.7%, 66.7% and 66.7%, respectively, in patients with severe anterior compression and 16.7%, 33.3%, 33.3%, 33.3% and 33.3%, respectively, in patients with severe posterior compression. PLDD had certain positive efficacy on the treatment of lumbar spinal stenosis, which was more significant on LSS dominated by the anterior compression than that by the posterior compression. PMID:23996073
Radiological considerations: patient selection for percutaneous laser disc decompression.
Botsford, J A
Percutaneous laser disc decompression (PLDD) is an effective method of treating the lumbar herniated nucleus pulposis (HNP) that is both contained by the annular/posterior longitudinal ligament (PLL) complex and connected to the parent disc of origin. Not all radiological studies have the same ability to diagnose this specific type of herniation and therefore are not equally useful in the preoperative evaluation of the PLDD candidate. Ninety PLDD treated patients were retrospectively reviewed to determine which of the four most commonly performed lumbar imaging exams, when abnormal, correlated with a successful outcome. Overall MacNab criteria improvement occurred in 73.3% of PLDD-treated patients. An abnormal CT discogram correlated with PLDD success in all patients treated (100%). An abnormal MRI, CT, or myelogram correlated with success in 75% or less of patients treated. The theoretical reasons for the superiority of CT discography are discussed and the diagnostic potential of all major lumbar imaging modalities is reviewed. A diagnostic decision scheme for the evaluation of the prospective PLDD patient is presented. PMID:10150671
Percutaneous laser discectomy of cervical discs: preliminary clinical results.
Siebert, W
Thirty-one patients with herniated cervical discs were treated with PLDD from 1991 to 1993. In 1990, a few of these patients were treated with the Nd:YAG laser with no complications. Since 1991 we have used the holmium:YAG laser; 28 of the 31 patients experienced pain relief in a 6-week follow-up. PLDD for the cervical discs is a viable therapy. PMID:10150647
Benefits of multislice CT-fluoroscopy needle guidance in Percutaneous Laser Disc Decompression (PLDD)
NASA Astrophysics Data System (ADS)
Brat, Hugues G.; Bouziane, Tarik; Lambert, Jean; Divano, Luisa
Multislice fluoro-CT allows 3 dimensional millimetric precision in needle guidance and placement. The main benefit of this technique is a volumetric approach with precise management of the patient's Z-axis. This allows performing fast procedures, low x-ray exposure of the patient, central needle positioning inside the disc, absence of radicular lesion, absence of technical failure of the procedure. It can be considered therefore as the safest technique to perform fast and efficient Percutaneous Laser Disc Decompression (PLDD).
Percutaneous laser disc decompression: a 17-year experience.
Choy, Daniel S J
In this review, we analyze our effort to demonstrate the effectiveness of a new approach to the treatment of herniated disc disease using Nd:YAG laser energy introduced into a herniated disc under fluoroscopic control and local anesthesia. 2400 PLDD procedures (combined number of decompressions in cervical, thoracic, and lumbar discs were performed in the past 18(1/2) years in 1275 patients. The overall success rate according to the MacNab criteria was 89%. The complication rate (only infectious disciitis) was 0.4%; all 10 patients with complications were cured with appropriate antibiotics. The recurrence rate was 5%, and usually due to reinjury. There were no deaths, and no cases of nerve or cord damage. PLDD is a safe and effective outpatient procedure for the treatment of herniated disc disease with the advantages of relative non-invasiveness, usually immediate relief of back and sciatic pain, early return to work (generally 5-6 days), and a low complication and recurrence rate. It can also be repeated if necessary as many as five times. PMID:15671713
Percutaneous Laser Disc Decompression (PLDD): Experience and Results From Multiple Centers and 19,880 Procedures
NASA Astrophysics Data System (ADS)
Paolo Tassi, Gian; Choy, Daniel S. J.; Hellinger, Johannes; Hellinger, Stefan; Lee, Sang-Ho
In mid-February 1986, Peter Ascher and Daniel Choy performed the first Percutaneous Laser Disc Decompression (PLDD) at the Neurosurgical Department, University of Graz, Graz, Austria. It was planned to deliver 1000 joules with a Nd:YAG laser to a herniated L4-5 disc causing sciatica. At 600 joules the procedure was terminated because the pain was gone. Since then, PLDD has spread all over the world, with procedures being performed in the entire spine except for T1-T4 because these discs do not permit percutaneous access with a needle. The success rate has ranged from 70 to 89%, and the complication rate, chiefly discitis, from 0.3 to 1.0%. When successful, return to normal work averages one week. Long term follow-up to 23 years yields a recurrence rate of 4-5%.
Comparison Of Percutaneous Laser Discectomy With Other Modalities For The Treatment Of Herniated Lumbar Discs And Cadaveric Studies Of Percutaneous Laser Discectomy
NASA Astrophysics Data System (ADS)
Johansen, W. E.; Smith, Chadwick F.; Vangsness, Thomas; McEleney, Emmett T.; Yamaguchi, Ken; Bales, Peter
Current modalities for treating a herniated lumbar disc include standard open discectomy, microsurgical discectomy, chemonucleoysis and percutaneous discectomy. The Food and Drug Administration has not yet approved percutaneous laser discectomy for clinical investigation. The investigators believe that percutaneous laser discectomy combines the efficacy of both chemonucleoysis and percutaneous discectomy with the safety of both open standard discectomy and microsurgical discectomy. The investigators removed two lumbar discs from a cadaveric spine and weighed each of them. The two lumbar discs weighed in the range of 13.654 grams and 15.713 grams, respectively. The investigators initiated several series of 10 firing cycles from a surgical carbon dioxide laser system. In each firing cycle the surgical carbon dioxide laser system delivered a beam of light energy having an output power of 18.0 watts at pulse duration of 0.045 second at the rate of 15 pulses per second for a period of 6 seconds and vaporized approximately 325 milligrams of disc material. Based on the findings of other investigators reported in the literature relating to percutaneous discectomy the investigators postulated that 10 to 20 firing cycles are required to vaporize 30 to 40% (2.4 to 6.4 grams) of the disc material. The investigators initiated two series of 10 firing cycles in order to perform laser discectomy in a third lumbar disc of the cadaveric spine in situ. The investigators harvested and then bisected the laser-treated third lumbar disc for gross review. Their gross findings indicated a high probability of success For percutaneous laser discectomy.
Percutaneous laser disc decompression for thoracic disc disease: report of 10 cases
Haufe, Scott M.W.; Mork, Anthony R.; Pyne, Morgan; Baker, Ryan A.
Background: Discogenic pain or herniation causing neural impingement of the thoracic vertebrae is less common than that in the cervical or lumbar regions. Treatment of thoracic discogenic pain usually involves conservative measures. If this fails, conventional fusion or discectomy can be considered, but these procedures carry significant risk. Objectives: To assess the efficacy and safety of percutaneous laser disc decompression (PLDD) for the treatment of thoracic disc disease. Methods: Ten patients with thoracic discogenic pain who were unresponsive to conservative intervention underwent the PLDD procedure. Thoracic pain was assessed using the Visual Analog Scale (VAS) scores preoperatively and at 6-month intervals with a minimum of 18-months follow-up. Patients were diagnosed and chosen for enrollment based on abnormal MRI findings and positive provocative discograms. Patients with gross herniations were not included. Results: Length of follow-up ranged from 18 to 31 months (mean: 24.2 mo). Median pretreatment thoracic VAS score was 8.5 (range: 5-10) and median VAS score at final follow-up was 3.8 (range: 0-9). Postoperative improvement was significant with a 99% confidence interval. Of interest, patients generally fell into two groups, those with significant pain reduction and those with little to no improvement. Although complications such as pneumothorax, discitis, or nerve damage were possible, no adverse events occurred during the procedures. Limitations: The study is limited by its small size and lack of a sham group. Larger controlled studies are warranted. Conclusions: With further clinical evidence, PLDD could be considered a viable option with a low risk of complication for the treatment of thoracic discogenic pain that does not resolve with conservative treatment. PMID:20567616
Percutaneous laser disc decompression (PLDD) update: focus on device and procedure advances.
Choy, D S
This discussion is an update on the U.S. advances in percutaneous laser disc decompression (PLDD). This report summarizes the knowledge that has been gained about the procedure, advances in technique, and increased information about the three lasers currently in use for PLDD: KTP, Nd:YAG, and holmium. A new surgical approach to the L5-S1 disc is described. It is concluded that PLDD has become an established procedure that will be more widely used because it is simple, effective, and reasonably safe. PMID:10146384
Lumbar percutaneous KTP532 wavelength laser disc decompression and disc ablation in the management of discogenic pain.
Knight, Martin; Goswami, Ankul
The objective of this research was to determine the outcome of laser disc decompression and laser disc ablation in the management of painful degenerative disc disease with or without associated disc prolapse. Nonendoscopic percutaneous laser disc decompression was performed under x-ray control via the posterolateral approach with side-firing probes. All patients with chronic back pain who had reproduced pain during discography of a nature, pattern, and distribution similar to what they experienced normally were included in the study. Magnetic resonance which confirmed stenosis and sequestrated discs, and patients with acute neurological findings were excluded from the study. Laser disc decompression or ablation was done using the KTP532 wavelength. The functional outcome was assessed prospectively using the Oswestry Disability Index. Clinical benefit was considered significant in those patients with a percentage change in the index of > or =50% at review 3-9 years (mean, 5.33 years) following surgery. A total of 52% of patients demonstrated a sustained significant clinical benefit, with an additional 21% in whom functional improvement was noted. Cohort integrity was 67%. Long-term benefit of the laser disc ablation and decompression for discogenic pain suggests a mechanism other than principally mechanical as a cause of chronic back and sciatic pain. It may suggest that efficacy occurs by reduction in the intradiscal production of irritative products and by an effect upon discal and annular neoneuralization. The sustained nature of the benefit after long-term preoperative symptoms (mean, 4.7 years) rules out any placebo effect. Selection should be restricted to patients without significant lateral recess stenosis, retrolisthesis or olisthesis of > or =3 mm, significant dorsal or foraminal osteophytosis, extrusion, or sequestration. PMID:11902355
Treatment of Lumbar Intervertebral Disc Herniation Using C-Arm Fluoroscopy Guided Target Percutaneous Laser Disc Decompression
Zhao, Xu-Li; Xu, Yong-Guang; Zhao, Xue-Jun; Song, Wen-Ge; Zheng, Hong
Abstract Objective: To evaluate the safety and therapeutic efficacy of target percutaneous laser disc decompression (T-PLDD) for the treatment of lumbar disc herniation. Background data: PLDD using the Nd:YAG laser has been regarded as an effective alternative treatment for disc herniation. However, all the previous studies were concentrated on vaporizing the nucleus pulposus in the intervertebral space. We hypothesize that insertion of the needle into the extruded part of the nucleus pulposus will decrease its volume and provide superior clinical effects compared to therapies that decrease the volume of the intradiscal nucleus pulposus. Materials and methods: A total of 25 patients suffering from posterolateral extruded but nonsequestered lumbar intervertebral disc herniation were treated with T-PLDD. After treatment, the patients were followed up and the therapeutic effect was assessed at 1, 3, 6, and 12 months using the modified MacNab criteria. Results: The success rate was 80.0% (18 of 25), 88.0% (22 of 25), 92.0% (23 of 25), and 92.0% (23 of 25) at 1, 3, 6, and 12 months respectively. No serious complications occurred in any of the patients. Furthermore, we did not observe any neurological sequelae. Conclusions: T-PLDD can significantly decrease pain and improve function of patients who have extruded but nonsequestered lumbar intervertebral disc herniation. PMID:22150064
The clinical study of percutaneous disc decompression of treating herniation of cervical disc with Nd:YAG laser
NASA Astrophysics Data System (ADS)
Zhang, Dianxue; Cheng, Hefu; Wang, Jindong
Objective: The possibility of PLDD (percutaneous laser disc decompression) and an ideal non-operative method which is long everlasting effect for PLDD was investigated. Methods: 159 patients of Cervical Disc Herniation with PLDD were studied. All the herniated discs were irradiated with 1015J/S Nd:YAG laser quantum through optical-fiber under the supervision of C-arm X-ray. Results: All the patients were followed and reexamined CT or MRI after one to six months of PLDD. The result of cured (67.92%), excellent (24.53%), moderation (5.66%), non-effect (1.88%) was got. The excellent rate was 88.24%. The effective rate was 97.65%. Non-effective rate was 2.35%. Conclusion: When irradiated with Nd:YAG laser, the nucleus pulposus was vapouring, charring and coagulating. The volume and inner-pressure of the disc decreased. So the symptoms and signs improved. The main value of this methods were micro-damage, non-operation, no bleeding, no bone injury, good therapy effect, quick recovery, lesser pain, safety and excellent long everlasting effect. It is an ideal non-operative method of treating PLDD.
CT-guided Percutaneous Laser Disc Decompression (PLDD): prospective clinical outcome
NASA Astrophysics Data System (ADS)
Brat, Hugues G.; Bouziane, Tarik; Lambert, Jean; Divano, Luisa
Percutaneous Laser Disc Decompression (PLDD) is a minimal invasive and effective treatment for contained lumbar disc hernias with correspondent radicular pain. This prospective study evaluates clinical efficacy of patients treated with PLDD under CT-fluoroscopic guidance. An independent observer assessed clinical outcome in a series of 40 consecutive patients at a mean follow-up of 7.5 months after treatment. According to Mac Nab criteria, 80% of patients experienced a good response to PLDD, 12.5% a fair response and 7.5% a poor response. 37 patients (92.5%) were back at work after 3 weeks. This technique could represent an alternative and secure treatment to conventional surgery for contained disc hernias.
Rapid correction of neurologic deficits by percutaneous laser disc decompression (PLDD).
Choy, D S
Immediate correction of neurologic deficits due to herniated disc disease following percutaneous laser disc decompression (PLDD) has not previously been reported. In a review of 182 cases of herniated intervertebral disc disease with radicular pain syndromes, the author observed a high percentage of return of absent ankle and knee jerk reflexes, return of straight leg raising to normal, and a change of the characteristic rolling to one side, bending the knees, and propping up with the hands as the usual maneuver to change from a supine to a sitting position ("Choy sign") to an ability to sit up directly by trunk flexion, immediately, and at 1 day after PLDD. The neurophysiologic implications are discussed. PMID:9484094
Percutaneous laser disc decompression (PLDD): 352 cases with an 8 1/2-year follow-up.
Choy, D S
Percutaneous laser disc decompression (PLDD) was pioneered by Dr. Peter Ascher and myself in 1986. This report describes patient selection, operative technique, laser dosimetry, and results in 352 cases with an 8 1/2-year follow-up. The conclusion is that PLDD is relatively non-invasive, safe, simple and effective. PMID:10150569
Percutaneous laser lumbar disc decompression - mechanism of action, indications and contraindications.
Maksymowicz, Wojciech; Barczewska, Monika; Sobieraj, Andrzej
This article describes the development of minimally invasive methods in the treatment of lumbar discopathy, with particular attention to percutaneous laser disc decompression (PLDD). The authors discus the therapeutic operating mechanism of PLDD, emphasizing the importance of the thermal characteristics of laser light, which is responsible for the vaporization and ablation of a small amount of tissue from the nucleus pulposus. This causes a significant reduction in pressure in the closed structure of the disc, and consequently reduced compression exerted by the disk on the dural sac and the nerve roots. Improvement in the flow of cerebro-spinal fluid has also been observed on the level at which the operation is performed. On the basis of our own experience and the reports of other authors, we have specified indications and contra-indications for PLDD. Our conclusion is that PLDD is an effective treatment method for low back pain and ischialgia caused by protrusion or herniation of the nucleus pulposus, with elimination or significant reduction in symptoms in over 75% of those treated; reduction or resolution of neurological deficits that arise in the course of lumbar discopathy has also been observed. This method enables one-stage treatment of multi-level degenerative changes in the intervertebral disc. The only absolute contraindications for PLDD are the presence of sequestration, disturbances in blood coagulation, and bacterial infection. PMID:17675991
Effectiveness of percutaneous laser disc decompression versus conventional open discectomy in the treatment of lumbar disc herniation; design of a prospective randomized controlled trial
Brouwer, Patrick A; Peul, Wilco C; Brand, Ronald; Arts, Mark P; Koes, Bart W; Berg, Annette A van den; van Buchem, Mark A
Background The usual surgical treatment of refractory sciatica caused by lumbar disc herniation, is open discectomy. Minimally invasive procedures, including percutaneous therapies under local anesthesia, are increasingly gaining attention. One of these treatments is Percutaneous Laser Disc Decompression (PLDD). This treatment can be carried out in an outpatient setting and swift recovery and return to daily routine are suggested. Thus far, no randomized trial into cost-effectiveness of PLDD versus standard surgical procedure has been performed. We present the design of a randomized controlled trial, studying the cost-effectiveness of PLDD versus conventional open discectomy in patients with sciatica from lumbar disc herniation. Methods/design The study is a randomized prospective multi-center trial, in which two treatment strategies are compared in a parallel group design. Patients (age 18–70 years) visiting the neurosurgery department of the participating hospitals, are considered for inclusion in the trial when sciatica due to lumbar disc herniation has lasted more than 8 weeks. Patients with disc herniation smaller than 1/3 of the spinal canal diameter, without concomitant lateral recess stenosis or sequestration, are eligible for participation, and are randomized into one of two treatment arms; either Percutaneous Laser Disc Decompression or conventional discectomy. The functional outcome of the patient, as assessed by the Roland Disability Questionnaire for Sciatica at 8 weeks and 1 year after treatment, is the primary outcome measure. The secondary outcome parameters are recovery as perceived by the patient, leg and back pain, incidence of re-intervention, complications, quality of life, medical consumption, absence of work and secondary costs. Discussion Open discectomy is still considered to be the golden standard in the surgical treatment of lumbar disc herniation. Whether Percutaneous Laser Disc Decompression has at least as much efficacy as the
Treatment of lumbar disc herniation by percutaneous laser disc decompression (PLDD) and modified PLDD
NASA Astrophysics Data System (ADS)
Chi, Xiao fei; Li, Hong zhi; Wu, Ru zhou; Sui, Yun xian
Objective: To study the micro-invasive operative method and to compare the effect of treatment of PLDD and modified PLDD for Lumbar Disc Herniation. Method: Vaporized part of the nucleus pulposus in single or multiple point after acupuncture into lumbar disc, to reach the purpose of the decompression of the lumbar disc. Result: Among the 19 cases of the regular PLDD group, the excellent and good rate was 63.2%, and among the 40 cases of the modified PLDD group, the excellent and good rate was 82.5%. Conclusion: The modified PLDD has good effect on the treatment for lumbar disc herniation.
Complications of non-endoscopic percutaneous laser disc decompression and nucleotomy with the neodymium: YAG laser 1064 nm.
Hellinger, J
In this review, we discuss how nonendoscopic percutaneous laser disc decompression (PLDD) and nucleotomy, using the YAG laser 1064, now has reinforced itself as a minimally invasive procedure in discogenic, vertebral pain syndromes, created by bulging, protrusions, and contained and uncontained extrusions in all areas of the spine. The rate of complication is an important criterion of the application of this new method. 3377 patients were treated with this method in the period of November 11, 1989 to April 30, 2002. While 356 patients' cervical spine was operated on, a further 38 patients had their thoracic spine operated on. Six weeks later, a prospective, consecutive control followed with an uninterrupted recording. Subsequently, all complications that occurred in this time frame were recorded. A comparison was carried out between the complication rate as covered by the literature of other intradiscal percutaneous methods and open disc surgery. Using the Nd-YAG laser 1064 nm, PLDD is generally evaluated with a complication rate of 0.5%. In the cervical spine area, the complication rate was 1.0%. No significant complications followed the thoracic intervention. In comparison to figures suggested by the relevant literature regarding possible complications with other procedures, this particular procedure is relative risk-free. In conjunction with the satisfying results regarding pain and paralysis removal, the extraordinarily low complication density of Nd-YAG PLDD culminates in the recommendation that the procedure should be applied to patients who are between unsuccessful conservative therapy and other operative methods. PMID:15671715
Early results of percutaneous laser disc decompression (PLDD) as a treatment of discopathic lumbar pain.
Sobieraj, Andrzej; Maksymowicz, Wojciech; Barczewska, Monika; Konopielko, Marcin; Mazur, Dariusz
Background. The purpose of this paper is to present the technique of percutaneous laser disc decompression (PLDD), give some indications for its use, and provide a preliminary evaluation of the clinical effectiveness of this procedure in the treatment of low back pain, based on the authors' own experience. Material and methods. We performed a prospective analysis of treatment outcome in 212 patients who received PLDD in our clinic between March 2003 and January 2004, and who reported for the planned follow-up examination. Results. In 79.2% of these cases we achieved resolution or significant reduction of pain, and this effect persisted throughout the observation period of 6 weeks post surgery. In 3.8% of our patients, transient improvement was followed by intensification of low back pain, associated with the appearance of the most common complication after PLDD: inflammation of the disk and adjacent fragments of the elastic lamina of the vertebral bodies. Conclusions. In most cases PLDD is not a genuine alternative to open surgery on lumbar discopathy. It is most often administered to patients who have chronic pain from a slight extrusion of the disc, typically not qualified for surgery as the treatment method of choice. All other patients, even with larger herniations, can be administered PLDD as a last attempt at minimally invasive treatment prior to surgery, provided there are no obvious features of disruption of the posterior longitudinal ligament. PMID:17675983
Techniques of percutaneous laser disc decompression with the Nd:YAG laser.
Choy, D S
The great importance of correct needle placement with appropriate radiologic monitoring is emphasized. The needle tip must be just past the annulus, and the needle itself must be parallel to the disc axis, and preferably halfway between the superior and inferior end-plates. Dosimetry is described. A novel (extrathecal) approach to the L5-S1 disc when this cannot be entered from a dorsolateral angle is described. Our technique for cervical disc PLDD is briefly described. PMID:10150645
CT-guided percutaneous laser disc decompression with Ceralas D, a diode laser with 980-nm wavelength and 200-microm fiber optics.
Gevargez, A; Groenemeyer, D W; Czerwinski, F
The aim of this study was to evaluate the compact, portable Ceralas-D diode laser (CeramOptec; 980 + 30 nm wavelength, 200-microm optical fiber) concerning clinical usefulness, handling, and clinical results in the CT-guided treatment of herniated lumbar discs. The positioning of the canula in intradiscal space, the placement of the laser fiber into the disc through the lying canula, and the vaporization itself were carried out under CT-guidance. Due to the thin fiber optic, it was possible to use a thin 23-gauge canula. The laser procedure was performed in 0.1- to 1-s shots with 1-s pulse pause and 4-W power output. A total of 1650-2300 J was applied on each percutaneous laser disc decompression (PLDD). Results in 26 patients were established with a visual-analogue scale (VAS). On the follow-up examinations, 46% of the patients were absolutely pain free ( > 85 % VAS) and fully active in everyday life after 4 postoperative weeks. Thirty-one percent of patients were relieved of the leg pain but had occasional back pain without sensorimotor impairment. Fifteen percent sensed a slight alleviation ( > 50% VAS) of the radiate pain. Eight percent did not experience radicular or pseudo-radicular pain alleviation (< 25% VAS). Cerales-D proves to be an efficient tool for CT-guided PLDD on non-sequestered herniated lumbar discs. PMID:10939481
Percutaneous cervical nucleoplasty in the treatment of cervical disc herniation
Li, Jian; Zhang, Zai-Heng
Percutaneous disc decompression procedures have been performed in the past. Various percutaneous techniques such as percutaneous discectomy, laser discectomy, and nucleoplasty have been successful. Our prospective study was directly to evaluate the results of percutaneous cervical nucleoplasty (PCN) surgery for cervical disc herniation, and illustrate the effectiveness of PCN in symptomatic patients who had cervical herniated discs. From July of 2002 to June of 2005, 126 consecutive patients with contained cervical disc herniations have presented at the authors' clinic and treated by PCN. The patients' gender distribution for PCN was 65 male, 61 female. The age of patients ranged from 34 to 66 years (mean 51.9 ± 10.2 years). The levels of involvement were 21 cases at C3–4, 30 cases at C4–5, 40 cases at C5–6, and 35 cases at C6–7. The clinical outcomes, pain reduction and the segment stability were all recorded during this study. A clinical outcome was quantified by the Macnab standard and using VAS. The angular displacement (AD) ≥11° or horizontal displacement (HD) ≥3 mm was considered to be radiographically unstable. In the results of this study, puncture of the needle into the disc space was accurately performed under X-ray guidance in all cases. There was one case where the Perc-D Spine Wand had broken in the disc space during the procedure. The partial Perc-D Spine Wand, which had broken in the disc space could not be removed by the percutaneous cervical discectomy and thus remained there. There were no recurrent cases or complications in our series. Macnab standard results were excellent in 62 cases, good in 41 cases and fair in 23 cases. The rate of excellent and good was 83.73%. The VAS scores demonstrated statistically significant improvement in PCN at the 2-week, 1, 3, 6, and 12-month follow-up visits when compared to preoperational values (P < 0.01). There were no cases of instability following the PCN procedure. There was no
[Percutaneous laser disk decompression. Experience since 1989].
Siebert, W E; Berendsen, B T; Tollgaard, J
Since 1987/1988 percutaneous laser disc decompression (PLDD) has been used clinically for treatment of intervertebral disc prolapses. Credible prospective investigations that have been conducted since 1989 with large patient collectives are now available for analysis of their medium-term results and comparison with other minimally invasive procedures. Our follow-up examination of the first 180 patients treated with PLDD from 1989 to 1993 shows a success rate of 72.8%, similar to that with other percutaneous techniques (automated percutaneous lumbar discectomy, percutaneous lumbar discectomy, chemonucleolysis). To guarantee success, the spinal surgeon must have command of the correct technique and also use the appropriate instruments. Good results with the PLDD procedure can be procured when contraindications and indications for patient selection are strictly observed. Overall, our 5 year results seem encouraging. PMID:8622845
[Laser ablation of intervertebral disc: animal experiment].
Qi, Q; Dang, G D; Cai, Q L
The lumbar intervertebral discs (L3-6) were ablated through a transperitoneal approach in 12 adult dogs by using Nd: YAG laser (1.06 microns) with a 600 microns quartz fiber. The status of limbs motion and sphincter (bladder, bowel) was observed for evaluating the safety of laser irradiation. After irradiation, the animals were sacrificed at prescribed intervals of up to 40 weeks (2, 4, 8, 12 and 40 weeks after operation). The lumbar intervertebral discs were harvested and subjected to light microscopic observation. No dog had suffered from neurogenic dysfunction of limb motion and sphincter. Histological findings immediately after the irradiation showed the disc was vaporized and a cavity was made. After 2 and 4 weeks, fibrous tissues began to proliferate, but cartilaginous tissues replaced the fibrous tissues 12 weeks after the laser irradiation. No new bone formation was found within 40 weeks after operation. On the basis of this study and our previous cadaveric study, percutaneous laser disc decompression (PLDD) was applied in clinical practice in march of 1993. 10 patients underwent PLDD utilizing the same laser equipment. The average follow-up was 3 months. According to the Macnab's criteria, there was an excellent response in 7 patients and a good response in 3. PMID:7842915
Laser engineering of spine discs
NASA Astrophysics Data System (ADS)
Sobol, E.; Zakharkina, O.; Baskov, A.; Shekhter, A.; Borschenko, I.; Guller, A.; Baskov, V.; Omelchenko, A.; Sviridov, A.
The laser engineering of intervertebral discs is one of the branch of medical physics aimed at the development of minimally invasive laser medical techniques based on the effect of the controlled (time- and space-modulated) laser radiation on the structure and the field of mechanical stress of biological tissues. A new method for the laser engineering of the intervertebral discs and the differences of this approach from the existing physical methods of medical treatment are considered. The newly formed tissues of animals and humans are hystologically studied. Possible regeneration processes are discussed. A control system that provides for the treatment efficiency and safety is developed. The new laser medical equipment that is designed for the laser engineering of intervertebral discs is described, and the corresponding results of the clinical application are presented.
Standards of Practice: Quality Assurance Guidelines for Percutaneous Treatments of Intervertebral Discs
Kelekis, Alexis D. Filippiadis, Dimitris K.; Martin, Jean-Baptiste; Brountzos, Elias
Percutaneous treatments are used in the therapy of small- to medium-sized hernias of intervertebral discs to reduce the intradiscal pressure in the nucleus and theoretically create space for the herniated fragment to implode inward, thus reducing pain and improving mobility and quality of life. These techniques involve the percutaneous removal of the nucleus pulposus by using a variety of chemical, thermal, or mechanical techniques and consist of removal of all or part of nucleus pulposus to induce more rapid healing of the abnormal lumbar disc. These guidelines are written to be used in quality improvement programs for assessing fluoroscopy- and/or computed tomography-guided percutaneous intervertebral disc ablative techniques.
In vitro and in vivo fall of intradiscal pressure with laser disc decompression.
Choy, D S; Diwan, S
In vitro and in vivo measurements of intradiscal pressure under load and without load, respectively, before and after laser ablation of small volumes of nucleus pulposus revealed significant falls of intradiscal pressure. This is the basic principle underlying percutaneous laser disc decompression (PLDD). PMID:10148211
Clinical Outcomes of Percutaneous Plasma Disc Coagulation Therapy for Lumbar Herniated Disc Diseases
Kim, Sung Chul; Cho, Ki Hong
Objective This is prospective study of clinical outcomes of percutaneous plasma disc coagulation Therapy (PDCT) in patients with herniated lumbar disc disease (HLD) to evaluate the safety and efficacy in its clinical application and usefulness as a reliable alternative to microscopic discectomy. Methods Forty-six patients were enrolled in this study from April 2006 to June 2010. All patients had one-level HLD. Disc degeneration was graded on routine T2-weighted magnetic resonance Image (MRI) using the Pfirrmann's grading system and all index levels were grade 3 and grade 4. Indications for surgery were radiculopathy caused by disc protrusion with soft consistency. MRI was done at one month after the procedure in all patients to check post-PDCT change. The clinical outcomes were evaluated using Visual Analog Scales (VAS) score and MacNab's criteria. Results This study was approved by the Institutional Review Board of our institution. The age of the study population ranged from 16 to 59 years with a mean age of 37.2 years. There were 29 males and 17 females in this study. The mean period of clinical follow-up was 21 months. The average preoperative VAS score for radiculopathy was 7.4±1.4, while the final follow-up VAS score was 1.4±0.7 (p<0.001). In MacNab's criteria, 41 patients (89.1%) had achieved favorable improvement (excellent and good) until later follow-up. There were one patient from infection and two patients who needed to convert to open discectomy. Conclusion PDCT is a safe and efficient treatment modality in a selective patient with HLD. PMID:22396836
Percutaneous Disc Coagulation Therapy (PDCT) comparing with Automated Percutaneous Lumbar Discectomy (APLD) in Patients of Herniated Lumbar Disc Disease: Preliminary Report
Park, Cheon Wook; Lee, Joo Yong; Choi, Woo Jin
Objective Percutaneous techniques are rapidly replacing traditional open surgery. This is a randomized controlled trial study of clinical outcomes of Percutaneous Plasma Disc Coagulation Therapy (PDCT) in patients with HLD(herniated lumbar disc) as a new percutaneous access in comparison with Automated Percutaneous Lumbar Discectomy (APLD) in its clinical application and usefulness as a reliable alternative method. Methods The authors analyzed 25 patients who underwent PDCT randomized 1:1 to 25 who underwent APLD between June, 2010 and October, 2011. All patients had herniated lumbar disc diseases. The clinical outcomes were evaluated using Visual Analog Scales (VAS) score and MacNab's criteria. Results The age of the patients who underwent PDCT ranged from 29 to 88 years with a mean age of 51.8 years. The age of the APLD undergone patients' population ranged from 30 to 66 with a mean age of 46.0 years. The average preoperative VAS score in PDCT was 7.60 and 1.94 at 7months post-operatively, and in APLD was 7.32, and 3.53 at 7 months post-operatively (p<0.001). In Macnab's criteria, 20 patients (80%) had achieved favorable improvement (excellent and good) in PDCT group. In Macnab's criteria, 16 patients (64%) had achieved favorable improvement in APLD group (p<0.001). Conclusion PDCT can be considered a viable option as a new percutaneous access to herniated lumbar disc. PDCT showed to be more effective than APLD in this study, allowing stable decompression and safe minimally invasive operation to an area desired by the operator in lumbar disc herniation patients, although further long term clinical evaluations are still necessary. PMID:25983808
MR guidance of laser disc decompression: preliminary in vivo experience.
Steiner, P; Zweifel, K; Botnar, R; Schoenenberger, A W; Debatin, J F; von Schulthess, G K; Hodler, J
The purpose of this study was to perform percutaneous laser disc decompression (PLDD) under MR guidance in an open configuration 0. 5-T MR system. Following failed conservative treatment for 6 months, eight patients with contained disc herniations were enrolled in the study. Following MR guided introduction of the laser fiber into the targeted disc space, the laser-induced temperature distribution was visualized using a color-coded subtraction technique based on a T1-weighted GRE sequence. In seven patients PLDD could be performed. In all cases laser effects were depicted by MR. In this regard the color-coded technique was found to be superior to conventional magnitude images. Whereas no apparent decrease in the extent of herniation was discovered immediately following PLDD, T2-weighted FSE images showed signal intensity alterations in two of the seven patients. Clinical evaluation, obtained 3-4 months after PLDD, revealed a fair (n = 2) or good (n = 4) response to the treatment. One patient showed no change in symptoms. MR guidance and monitoring of PLDD is feasible within an open 0.5-T system and seems to render PLDD more safe and controllable. PMID:9569329
Percutaneous holmium laser fulguration of calyceal diverticula.
Alwaal, Amjad; Azhar, Raed A; Andonian, Sero
Introduction. Calyceal diverticular stones are uncommon findings that represent a challenge in their treatment, due to the technical difficulty in accessing the diverticulum, and the high risk of their recurrence. Current percutaneous technique for calyceal diverticular stones involves establishing a renal access, clearing the stone, and fulguration of the diverticular lining with a roller-ball cautery electrode using hypotonic irrigation solution such as sterile water or glycine solution which may be associated with the absorption of hypotonic fluids with its inherent electrolyte disturbances. Case Report. In this paper, we present for the first time percutaneous holmium laser fulguration of calyceal diverticula in 2 patients using normal saline. Their immediate postoperative sodium was unchanged and their follow-up imaging showed absence of stones. Both patients remain asymptomatic at 30 months post-operatively. Conclusion. This demonstrates that holmium laser is a safe alternative method to fulgurate the calyceal diverticulum after clearing the stone percutaneously. PMID:22606636
Percutaneous Transcatheter Aortic Disc Valve Prosthesis Implantation: A Feasibility Study
Sochman, Jan
Purpose: Over the past 30 years there have been experimental efforts at catheter-based management of aortic valve regurgitation with the idea of extending treatment to nonsurgical candidates. A new catheter-based aortic valve design is described.Methods: The new catheter-delivered valve consists of a stent-based valve cage with locking mechanism and a prosthetic flexible tilting valve disc. The valve cage is delivered first followed by deployment and locking of the disc. In acute experiments, valve implantation was done in four dogs.Results: Valve implantation was successful in all four animals. The implanted valve functioned well for the duration of the experiments (up to 3 hr).Conclusion: The study showed the implantation feasibility and short-term function of the tested catheter-based aortic disc valve. Further experimental studies are warranted.
Disc Volume Reduction with Percutaneous Nucleoplasty in an Animal Model
Kasch, Richard; Mensel, Birger; Schmidt, Florian; Ruetten, Sebastian; Barz, Thomas; Froehlich, Susanne; Seipel, Rebecca; Merk, Harry R.; Kayser, Ralph
Study Design We assessed volume following nucleoplasty disc decompression in lower lumbar spines from cadaveric pigs using 7.1Tesla magnetic resonance imaging (MRI). Purpose To investigate coblation-induced volume reductions as a possible mechanism underlying nucleoplasty. Methods We assessed volume following nucleoplastic disc decompression in pig spines using 7.1-Tesla MRI. Volumetry was performed in lumbar discs of 21 postmortem pigs. A preoperative image data set was obtained, volume was determined, and either disc decompression or placebo therapy was performed in a randomized manner. Group 1 (nucleoplasty group) was treated according to the usual nucleoplasty protocol with coblation current applied to 6 channels for 10 seconds each in an application field of 360°; in group 2 (placebo group) the same procedure was performed but without coblation current. After the procedure, a second data set was generated and volumes calculated and matched with the preoperative measurements in a blinded manner. To analyze the effectiveness of nucleoplasty, volumes between treatment and placebo groups were compared. Results The average preoperative nucleus volume was 0.994 ml (SD: 0.298 ml). In the nucleoplasty group (n = 21) volume was reduced by an average of 0.087 ml (SD: 0.110 ml) or 7.14%. In the placebo group (n = 21) volume was increased by an average of 0.075 ml (SD: 0.075 ml) or 8.94%. The average nucleoplasty-induced volume reduction was 0.162 ml (SD: 0.124 ml) or 16.08%. Volume reduction in lumbar discs was significant in favor of the nucleoplasty group (p<0.0001). Conclusions Our study demonstrates that nucleoplasty has a volume-reducing effect on the lumbar nucleus pulposus in an animal model. Furthermore, we show the volume reduction to be a coblation effect of nucleoplasty in porcine discs. PMID:23209677
Percutaneous Intradiscal Aspiration of a Lumbar Vacuum Disc Herniation: A Case Report
Pak, Kevin I.; Hoffman, David C.; Herzog, Richard J.
We report a case of an 83-year-old gentleman presenting with acute low back pain and radicular left lower extremity pain after golfing. A magnetic resonance imaging (MRI) of the lumbar spine revealed a low-signal-density lesion compressing the L5 nerve. A computed tomography scan was then ordered, confirming an extra-foraminal disc protrusion at the L5–S1 level, containing a focus of gas that was compressing the left L5 nerve root and communicating with the vacuum disc at L5–S1. After a failed left L5 transforaminal epidural steroid injection, the patient was brought back for a percutaneous intradiscal aspiration of the vacuum disc gas. This resulted in immediate relief for the patient. A follow-up MRI performed 2 months after the procedure found an approximate 25% reduction in the size of the vacuum disc herniation. Six months after the procedure, the patient remains free of radicular pain. This case report suggests that a percutaneous aspiration of gas from a vacuum disc herniation may assist in the treatment of radicular pain. PMID:22294964
Digital Video Disc Recorder Using Second Harmonic Generation Green Laser
NASA Astrophysics Data System (ADS)
Seo, Joong Eon; Park, In Sik; Oh, Young Nam; Lee, Seung Hoon; Seong, Pyong Yong; Jang, Yoon Ki; Shin, Dong Ho
A prototype of a digital video disc recorder (D-VDR) with laser-disc-quality video and compact-disc-quality audio is developed and demonstrated using a second harmonic generation (SHG) green laser, narrow-track magneto-optical disk (MOD), mark edge recording and data compression.
Comparison of Percutaneous Endoscopic Lumbar Discectomy and Open Lumbar Microdiscectomy for Recurrent Disc Herniation
Lee, Dong Yeob; Shim, Chan Shik; Ahn, Yong; Choi, Young-Geun; Kim, Ho Jin
Objective The purpose of this study was to compare clinical and radiological outcomes of percutaneous endoscopic lumbar discectomy (PELD) and open lumbar microdiscectomy (OLM) for recurrent disc herniation. Methods Fifty-four patients, who underwent surgery, either PELD (25 patients) or repeated OLM (29 patients), due to recurrent disc herniation at L4-5 level, were divided into two groups according to the surgical methods. Excluded were patients with sequestrated disc, calcified disc, severe neurological deficit, or instability. Clinical outcomes were assessed using Visual Analogue Scale (VAS) score and Oswestry Disability Index (ODI). Radiological variables were assessed using plain radiography and/or magnetic resonance imaging. Results Mean operating time and hospital stay were significantly shorter in PELD group (45.8 minutes and 0.9 day, respectively) than OLM group (73.8 minutes and 3.8 days, respectively) (p < 0.001). Complications occurred in 4% in PELD group and 10.3% in OLM group in the perioperative period. At a mean follow-up duration of 34.2 months, the mean improvements of back pain, leg pain, and functional improvement were 4.0, 5.5, and 40.9% for PELD group and 2.3, 5.1, and 45.0% for OLM group, respectively. Second recurrence occurred in 4% after PELD and 10.3% after OLM. Disc height did not change after PELD, but significantly decreased after OLM (p = 0.0001). Neither sagittal rotation angle nor volume of multifidus muscle changed significantly in both groups. Conclusion Both PELD and repeated OLM showed favorable outcomes for recurrent disc herniation, but PELD had advantages in terms of shorter operating time, hospital stay, and disc height preservation. PMID:20062565
Laser Discs, Barcodes, and Books--a Great Combination.
ERIC Educational Resources Information Center
Peto, Erica
Describes the use of barcodes to link laser discs with books in school libraries. Highlights include use of a barcode reader as a remote control device as well as a scanner, guidelines for making laser disc books, and a sidebar that explains how to make barcodes and describes software. (LRW)
Quantitative Analysis of Disc Degeneration Using Axial T2 Mapping in a Percutaneous Annular Puncture Model in Rabbits
Chai, Jee Won; Lee, Joon Woo; Kim, Su-Jin; Hong, Sung Hwan
Objective To evaluate T2 relaxation time change using axial T2 mapping in a rabbit degenerated disc model and determine the most correlated variable with histologic score among T2 relaxation time, disc height index, and Pfirrmann grade. Materials and Methods Degenerated disc model was made in 4 lumbar discs of 11 rabbits (n = 44) by percutaneous annular puncture with various severities of an injury. Lumbar spine lateral radiograph, MR T2 sagittal scan and MR axial T2 mapping were obtained at baseline and 2 weeks and 4 weeks after the injury in 7 rabbits and at baseline and 2 weeks, 4 weeks, and 6 weeks after the injury in 4 rabbits. Generalized estimating equations were used for a longitudinal analysis of changes in T2 relaxation time in degenerated disc model. T2 relaxation time, disc height index and Pfirrmann grade were correlated with the histologic scoring of disc degeneration using Spearman's rho test. Results There was a significant difference in T2 relaxation time between uninjured and injured discs after annular puncture. Progressive decrease in T2 relaxation time was observed in injured discs throughout the study period. Lower T2 relaxation time was observed in the more severely injured discs. T2 relaxation time showed the strongest inverse correlation with the histologic score among the variables investigated (r = -0.811, p < 0.001). Conclusion T2 relaxation time measured with axial T2 mapping in degenerated discs is a potential method to assess disc degeneration. PMID:26798222
The Early Stage Adjacent Disc Degeneration after Percutaneous Vertebroplasty and Kyphoplasty in The Treatment of Osteoporotic VCFs
Qian, Jun; Yang, Huilin; Jing, Juehua; Zhao, Hong; Ni, Li; Tian, Dasheng; Wang, Zhengfei
Background The purpose of this paper is to determine the early incidence of disc de- generation adjacent to the vertebral body of osteoporotic fracture treated with percutaneous vertebroplasty or balloon kyphoplasty and whether adjacent disc degeneration is accelerated by this two procedures. Methods 182 patients with painful vertebral compression fractures were treated. A total of 97 patients were enrolled in this prospective study. 97 patients with a mean age of 65.3 years were classified into control group and surgical treatment group of non-random. 35 patients were in contol group and 62 patients who were performed percutaneous vertebroplasty or balloon kyphoplasty in treatment group. X-ray and Magnetic resonance imaging were done at the first and final visit. The grade of disc degeneration above the fractured vertebral was confirmed by evaluation of bony oedema in the fat suppressed sequences and T2-weighted image of magnetic resonance imaging. The height of degenerative disc was measured on X-ray film. Results All patients were followed up two years after the first visit and the follow-up rate was 90.7% (88/97). The incidence of degeneration of adjacent disc above the fractured vertebral was 29.0% (9/31) in control group and 52.6% (30/57) in treatment group. It presented a statistically significant difference between two groups about the incidence of adjacent disc degeneration (P = 0.033). The percentage of adjacent disc height reduction in control group was 13.5% and 17.6% in treatment group. Statistically significant difference of VAS score and ODI was not found between the first evaluation postoperatively and the final follow-up in treatment group (P>0.05). Conclusions Disc degeneration adjacent to the fractured vertebral is accelerated by VP and BK procedures in the early stage, but clinical outcomes has not been weakened even in the presence of accelerated disc degeneration. PMID:23056283
Optimum Ho:YAG laser irradiation condition on percutaneous laser disk decompression (PLDD): in-vitro quantitive evaluation of influence on disk cells using three-dimensional cell culture system
NASA Astrophysics Data System (ADS)
Sato, Masato; Ishihara, Miya; Arai, Tsunenori; Asazuma, Takashi; Kikuchi, Toshiyuki; Kikuchi, Makoto; Fujikawa, Kyosuke
The purpose of this study is to evaluate the influence on disc cells after laser irradiation using three-dimensional (3-D) culture system and to clarify the optimum Ho:YAG laser irradiation condition on percutaneous laser disc decompression (PLDD) therapy. Since the Ho:YAG laser ablation is characterized by water-vapor bubble dynamics with pressure wave, thermal effect on cell metabolism might occur in the intervertebral disc. We studied the disc cell damage on the metabolic point of view to investigate the optimum irradiation parameter of the Ho:YAG laser. We have developed the 3-D cultured disc cell system using agarose gel to investigate laser - disc cell interaction. This culture system provides a highly in vivo-like environment for disc cells in which cell- extracellular matrix interactions appear to be more important than contacts among cells. Intervertebral discs were obtained from Japanese white. The isolated disc cells were seeded in 96-well culture plates at the cell densities of 1 X 106 cells/ml, and incubated for 12 days. A pulsed Ho:YAG laser was delivered through a 200 micrometer-core diameter single silica glass fiber. On the agarose gel including the 3-D cultured disc cells, we used the Ho:YAG laser irradiation energy ranging from 40 to 180 mJ/pulse at the fiber end. Cytotoxicity and matrix synthesis after the laser irradiations were evaluated in time course to determine the optimum condition of laser irradiations. It was confirmed that laser irradiation causes necrosis of the cells and additionally produces apoptosis depending on the condition. The ability of matrix synthesis was maintained even after the irradiation, which differed depending on the irradiation conditions. The optimum irradiation conditions seemed related to the preservation of intact area and the acceleration of matrix synthesis in reactive area.
Intradural lumbar disc herniation after percutaneous endoscopic lumbar discectomy: case report.
Tamaki, Yasuaki; Sakai, Toshinori; Miyagi, Ryo; Nakagawa, Takefumi; Shimakawa, Tateaki; Sairyo, Koichi; Chikawa, Takashi
A 64-year-old man was referred to the authors with low-back pain (LBP) and right leg pain with a history of previously diagnosed lumbar disc herniation (LDH) at L4-5. He had undergone 2 percutaneous endoscopic lumbar discectomies (PELDs) for the herniation at another institution, and according to the surgical record of the second surgery, a dural tear occurred intraoperatively but was not repaired. Postoperative conservative treatments such as an epidural block and blood patch had not relieved his persistent LBP or right leg pain. Upon referral to the authors, MRI and myelography revealed an intradural LDH. The herniated mass was removed by durotomy, and posterior lumbar interbody fusion was performed. His symptoms were partially improved after surgery. Primary suture is technically difficult when a dural tear occurs during PELD. Therefore, close attention should be paid to avoiding such tears, and surgeons should increase their awareness of intradural LDH as a possible postoperative complication of PELD. PMID:26068274
Treatment of cauda equina syndrome caused by lumbar disc herniation with percutaneous endoscopic lumbar discectomy.
Li, Xiaolong; Dou, Qingyu; Hu, Shuai; Liu, Jiaxiang; Kong, Qingquan; Zeng, Jiancheng; Song, Yueming
To evaluate the feasibility and clinical efficacy of percutaneous endoscopic lumbar discectomy (PELD) for cauda equina syndrome (CES) caused by disc herniation. 16 patients with CES caused by LDH at the early and middle stages of Shi's classification were selected as the objects of study, who underwent PELD. Clinical outcomes were assessed using the Macnab criteria and the visual analogue scale (VAS). The VAS for leg pain and back pain significantly decreased from preoperative scores of 7.67 ± 1.23 and 7.52 ± 1.42, respectively, to postoperative scores of 1.71 ± 0.53 and 3.18 ± 0.72. Thirteen patients showed favorable results. Complications included one patient of motor weakness, and one patient developed an ipsilateral recurrent herniation who finally acquired satisfactory result after reoperation. Hence, PELD could be used as an alternative surgical method for the treatment of CES in properly selected cases and appropriate patient selection and a reasonable surgical approach will give rise to better outcomes. PMID:26292929
Laser-assisted percutaneous endoscopic neurolysis.
Epstein, J M; Adler, R
Endoscopic lysis of adhesive scar utilizing a steerable fiberoptic scope is currently being performed by a growing number of physicians. Various techniques and medications are presently being used to lyse epidural adhesions as a way of improving refractory lumbar radiculopathies. We present a case report discussing laser-assisted endoscopic lysis with radiographic images before and after laser-assisted neurolysis. We were able to demonstrate improvement in the filling of the nerve root with epidural contrast after the laser lysis of scar. This correlated with improvement in pain without neurologic deficit. The laser may represent a useful adjunct in the treatment of pain due to epidural fibrosis. PMID:16906206
Efficacy of Percutaneous Epidural Neuroplasty Does Not Correlate with Dural Sac Cross-Sectional Area in Single Level Disc Disease
Ji, Gyu Yeul; Oh, Chang Hyun; Moon, Bongju; Choi, Seung Hyun; Yoon, Young Sul; Kim, Keung Nyun
Purpose Percutaneous epidural neuroplasty (PEN) is a minimally invasive treatment. The efficacy of PEN has been relatively well investigated; however, the relationship between the clinical effectiveness of PEN and the severity of spinal canal stenosis by disc material has not yet been established. The purpose of this study was to compare clinical outcomes of PEN according to the dural sac cross-sectional area in single level disc disease. Materials and Methods This study included 363 patients with back pain from single level disc disease with and without radiculopathy. Patients were categorized into groups according to spinal canal compromise by disc material: Category 1, less or more than 50%; and Category 2, three subgroups with lesser than a third, between a third and two thirds, and more than two thirds. Clinical outcomes were assessed according to the Visual Analog Scale (VAS) score for back pain and leg pain and Odom's criteria at 1, 3, 6, 12, and 24 months after treatment. Results The demographic data showed no difference between groups according to spinal canal compromise by disc material except age (older age correlated with more spinal canal compromise). The dural sac cross-sectional area did not correlate with the VAS scores for back and leg pain after PEN in single level disc disease in Groups 1 and 2. Odom's criteria after PEN were also not different according to dural sac cross-sectional area by disc material. Conclusion PEN is an effective procedure in treating single level lumbar disc herniation without affecting dural sac cross-sectional area. PMID:25837174
Percutaneous angioscopy after excimer laser angioplasty
NASA Astrophysics Data System (ADS)
Nakamura, Fumitaka; Kvasnicka, Jan; Geschwind, Herbert J.; Uchida, Yasumi
Angioscopy has proved to provide more detailed information on lesion morphology before and after interventional procedures than angiography. Therefore, to evaluate the effects of laser angioplasty, angioscopy was performed in five patients with peripheral or coronary vascular disease who underwent excimer laser angioplasty. The excimer laser was operated at 308 nm, 135 nsec, 25 Hz, and 40 - 60 mJ/mm2 and was coupled into multifiber wire-guided catheters of 1.4 to 2.0 mm diameter for coronary lesions and 2.2 mm for peripheral lesions. There were three coronary (one left anterior descending, one circumflex, one right coronary artery) and two peripheral (one common iliac artery, one superficial femoral artery) lesions. Angioscopy was successfully performed before and after laser ablation without any complications in all five lesions. The characteristics of angioscopic findings after excimer laser angioplasty consisted of flaps, fractures of plaques, and abundant tissue remnants. There was no apparent thermal injury. Recanalized channels were small and irregular. These results indicate that (1) angioscopy is effective and safe for evaluation of lesion morphology after laser angioplasty, (2) laser ablation does not result in thermal injury, and (3) irregular channels after recanalization and abundant tissue remnants may explain the suboptimal results after laser angioplasty.
The Use of Percutaneous Lumbar Fixation Screws for Bilateral Pedicle Fractures with an Associated Dislocation of a Lumbar Disc Prosthesis
Harrison, William D.; Harrison, David J.
Study Design. Case report. Objective. To identify a safe technique for salvage surgery following complications of total disc replacement. Summary of Background Data. Lumbar total disc replacement (TDR) is considered by some as the gold standard for discogenic back pain. Revision techniques for TDR and their complications are in their infancy. This case describes a successful method of fixation for this complex presentation. Methods and Results. A 48-year-old male with lumbar degenerative disc disease and no comorbidities. Approximately two weeks postoperatively for a TDR, the patient represented with acute severe back pain and the TDR polyethylene inlay was identified as dislocated anteriorly. Subsequent revision surgery failed immediately as the polyethylene inlay redislocated intraoperatively. Further radiology identified bilateral pedicle fractures, previously unseen on the plain films. The salvage fusion of L5/S1 reutilized the anterior approach with an interbody fusion cage and bone graft. The patient was then turned intraoperatively and redraped. The percutaneous pedicle screws were used to fix L5 to the sacral body via the paracoccygeal corridor. Conclusion. The robust locking screw in the percutaneous screw allowed a complete fixation of the pedicle fractures. At 3-year followup, the patient has an excellent result and has returned to playing golf. PMID:24294533
Randomized clinical trial comparing lumbar percutaneous hydrodiscectomy with lumbar open microdiscectomy for the treatment of lumbar disc protrusions and herniations
Cristante, Alexandre Fogaça; Rocha, Ivan Diasda; Marcon, Raphael Martus; de Barros Filho, Tarcísio Eloy Pessoa
OBJECTIVES: Hydrodiscectomy is a new technique used for percutaneous spinal discectomy that employs a high-intensity stream of water for herniated disc ablation and tissue aspiration. No previous clinical study has examined the effects of percutaneous hydrodiscectomy. The aim of this study is to evaluate the outcomes of hydrodiscectomy compared to open microdiscectomy regarding pain, function, satisfaction, complications and recurrence rates. METHODS: In this randomized clinical trial, patients referred to our tertiary hospital for lumbar back pain were recruited and included in the study if they had disc protrusion or small herniation in only one level, without neurological deficits and with no resolution after six weeks of conservative treatment. One group underwent open microdiscectomy, and the other group underwent percutaneous microdiscectomy via hydrosurgery. Function was evaluated using the Oswestry Disability Index and pain was assessed using a visual analog scale. Evaluations were performed preoperatively, and then during the first week and at one, three, six and twelve months postoperatively. Personal satisfaction was verified. Clinicaltrials.gov: NCT01367860. RESULTS: During the study period, 20 patients were included in each arm and 39 completed one-year of follow-up (one patient died of unrelated causes). Both groups exhibited equal improvement on the visual analog scale and Oswestry evaluations after treatment, without any significant differences. The improvement in the lumbar visual analog scale score was not significant in the hydrodiscectomy group (p=0.138). The rates of infection, pain, recurrence and satisfaction were similar between the two groups. CONCLUSION: Percutaneous hydrodiscectomy was demonstrated to be as effective as open microdiscectomy for reducing pain. The rates of complications and recurrence of herniation were similar between groups. Patient satisfaction with the treatment was also similar between groups. PMID:27276397
Transforaminal Percutaneous Endoscopic Discectomy for Lumbar Disc Herniation in Parkinson's Disease: A Case-Control Study
Giovannopoulou, Eirini; Charitoudis, George; Kazakos, Konstantinos
Study Design A case-control study. Purpose To investigate the effectiveness of transforaminal percutaneous endoscopic discectomy (TPED) in Parkinson's disease (PD). Overview of Literature Patients with PD frequently suffer from radiculopathy and low back pain. Additionally, they demonstrate higher complication rates after open spine surgery. However, the clinical outcome of minimally invasive techniques for lumbar discectomy, such as TPED, have not been established for this population. Methods Patients diagnosed with lumbar disc hernia were divided into Group A (11 patients diagnosed with PD), and Group B (10 patients as the control, non-PD group). All patients underwent TPED. Indexes of visual analogue scale (VAS) for leg pain and Oswestry disability index (ODI) were assessed right before surgery and at six weeks, three months, six months and one year post-surgery. Results At the baseline visit, groups did not differ significantly with age (p=0.724), gender (p=0.835), level of operation (p=0.407), ODI (p=0.497) and VAS (p=0.772). Parkinson's patients had higher scores in ODI at every visit, but the outcome was statistically significant only at 3 months (p=0.004) and one year (p=0.007). Similarly, VAS measurements were higher at each time point, with the difference being significant at 3 (p<0.001), 6 (0.021), and 12 (p<0.001) months after surgery. At the end of a year of follow up, ODI was reduced by 49.6% (±16.7) in Group A and 59.2% (±8.0) in Group B (p=0.111), translating to a 79.5% (±13.0) and 91.5% (±4.1) average improvement in daily functionality (p=0.024). VAS was reduced by 59.1 mm (±11.8) in Group A and 62.2 mm (±7.4) in Group B (p=0.485), leading to an 85.3 % (±4.0) and 91.9% (±2.6) general improvement in leg pain (p<0.001). Conclusions Our data indicate that TPED led to satisfactory improvement in leg pain and daily living in PD patients a year after surgery. PMID:27559446
Evaluation of different laser wavelengths on ablation lesion and residual thermal injury in intervertebral discs of the lumbar spine.
Plapler, Hélio; Mancini, Marília W; Sella, Valéria R G; Bomfim, Fernando R C
Laser discectomy or nucleotomy is an increasingly important method for less invasive procedures of column, but the ideal kind of laser is still not established. As the wavelength is an important parameter for water absorption, this study was performed to investigate the action of the laser emission in the near infrared (808 to 1908 nm) region in the context of surgical procedures for percutaneous intervertebral disc decompression (nucleotomy). Forty intervertebral discs from pigs lumbar spines were irradiated with laser (λ = 808, 980, 1470 and 1908 nm), 1-s on/off time cycles, for 120 cycles and 10 W of power (808, 980, and 1470 nm) or 240 cycles and 5 W of power (1908 nm), with total power of 1200 J, and subjected to microscopic evaluation through hematoxylin-eosin (HE) staining in order to measure the ablation lesions and the residual thermal injury. Ten other discs were not irradiated and worked as controls. The ablation lesions were measured (in mm) at 1.08 ± 1.25, 1.70 ± 0.63, 2.23 ± 1.02, 1.37 ± 0.39, and 0.94 ± 0.41 (median ± SD) for the control, 808, 980, 1470, and 1908 nm groups, respectively. The difference between 1908 nm and all the other groups was statistically significant (p < 0.05). The residual thermal injury was less evident in 1908 nm laser and sharper in 980 nm laser wavelengths. The laser at a wavelength of 1908 nm was considered the most efficient for the vaporization of the nucleus pulposus, followed by the laser wavelengths of 1470, 808, and 980 nm, and proved to be useful for laser nucleotomy procedure. PMID:26796705
Experimental study using diode laser in discs: the healing process in discs and adjacent vertebrae after laser irradiation
NASA Astrophysics Data System (ADS)
Naga, Kumi; Nakai, Sadaaki; Maehara, Kazuyuki; Nishimoto, Seiji
The direct and secondary changes following diode laser irradiation of intervertebral discs were studied in rabbits. A quartz fiber was inserted into the discs, and laser irradiation was applied. Subsequently, the lumbar vertebrae were extracted en bloc, and subjected to sagittal magnetic resonance (MR) imaging and histologic examination immediately after irradiation, and 3, 12, and 24 weeks after irradiation. MR images showed low signal intensity of the intervertebral discs on T2-weighted images 3 weeks after irradiation, which remained unchanged to 24 weeks. Although the signal intensity of the adjacent vertebral bodies remained unchanged on T1-weighted images, the intensity was high on T2-weighted images 3 weeks after irradiation, but had reverted to normal or was low 12 to 24 weeks after irradiation. On histologic examination, the inner layer of the annulus fibrosus was seen to protrude into the void created by vaporization of the nucleus pulposus 3 weeks after irradiation. Multinuclear chondrocytes were observed, as if the disc was being reconstructed. Fibrous tissue in the epiphysis and metaphysis was observed soon after irradiation but decreased over time and was replaced by normal bone marrow.
Feasibility and Efficacy of Percutaneous Lateral Lumbar Discectomy in the Treatment of Patients with Lumbar Disc Herniation: A Preliminary Experience
Jiang, Wenjin; Sun, Bolin; Sheng, Qirui; Song, Xuepeng; Zheng, Yanbo; Wang, Ligang
Objective. This study was aimed at evaluating the effectiveness and safety of percutaneous lateral lumbar discectomy (PLLD) in treating patients with lumber disc herniation. Methods. A total of 183 patients with lumbar disc herniation were recruited to receive PLLD surgery from April 2006 to October 2011. All the adverse effects were recorded during the follow-up at 1, 3, 6, and 12 months after PLLD. The clinical outcomes were determined by visual analog scale and Japanese Orthopaedic Association score. Results. The surgery was performed successfully in all patients (102 males and 81 females aged from 21 to 66 years) with a mean 16.6-month follow-up (range from 26 to 65 months). No postoperative complications, including intestinal and vascular complications, nerve injuries, and postoperative infections, were associated with PLLD. At one month after surgery, visual analog scale (3.12±1.44 versus 6.76±2.31, P<0.05) was significantly lower than the baseline and was sustained until 24 months after surgery (3.25 ± 1.78 versus 6.76±2.31, P<0.05). Besides that, Japanese Orthopaedic Association score (25.25±3.21 versus 11.78±2.38, P<0.05) was increased when compared to the baseline. Conclusions. PLLD was a promising, mini-invasive, and effective treatment for lumber disc herniation. PMID:25695066
Percutaneous needle placement using laser guidance: a practical solution
NASA Astrophysics Data System (ADS)
Xu, Sheng; Kapoor, Ankur; Abi-Jaoudeh, Nadine; Imbesi, Kimberly; Hong, Cheng William; Mazilu, Dumitru; Sharma, Karun; Venkatesan, Aradhana M.; Levy, Elliot; Wood, Bradford J.
In interventional radiology, various navigation technologies have emerged aiming to improve the accuracy of device deployment and potentially the clinical outcomes of minimally invasive procedures. While these technologies' performance has been explored extensively, their impact on daily clinical practice remains undetermined due to the additional cost and complexity, modification of standard devices (e.g. electromagnetic tracking), and different levels of experience among physicians. Taking these factors into consideration, a robotic laser guidance system for percutaneous needle placement is developed. The laser guidance system projects a laser guide line onto the skin entry point of the patient, helping the physician to align the needle with the planned path of the preoperative CT scan. To minimize changes to the standard workflow, the robot is integrated with the CT scanner via optical tracking. As a result, no registration between the robot and CT is needed. The robot can compensate for the motion of the equipment and keep the laser guide line aligned with the biopsy path in real-time. Phantom experiments showed that the guidance system can benefit physicians at different skill levels, while clinical studies showed improved accuracy over conventional freehand needle insertion. The technology is safe, easy to use, and does not involve additional disposable costs. It is our expectation that this technology can be accepted by interventional radiologists for CT guided needle placement procedures.
A Modified Approach of Percutaneous Endoscopic Lumbar Discectomy (PELD) for Far Lateral Disc Herniation at L5-S1 with Foot Drop.
Chun, Eun Hee; Park, Hahck Soo
Foraminal or extraforaminal Far Lateral Disc Herniations (FLDH) extending into or beyond the foraminal zone have been recognized as between 7-12% of all lumbosacral disc herniations. Conventional posterior laminectomy may not provide good access to a herniation that lies far lateral to the lateral margin of the pedicle. Use of the endoscopic technique through a percutaneous approach to treat such FLDH patients can decrease the surgical morbidity while achieving better outcomes. We made an effort to utilize the advantages of percutaneous endoscopic lumbar discectomy (PELD) and to determine the appropriate approach for FLDH at the level between the 5th Lumbar and first Sacral vertebrae(L5-S1). The authors present a case of an endoscopically resected lumbar extruded disc of the left extraforaminal zone with superior foraminal migration at the level of L5-S1, which had led to foot drop, while placing the endoscope in the anterior epidural space without facetectomy. PMID:26839673
Patient skin dose measurements using a cable free system MOSFETs based in fluoroscopically guided percutaneous vertebroplasty, percutaneous disc decompression, radiofrequency medial branch neurolysis, and endovascular critical limb ischemia.
Falco, Maria D; Masala, Salvatore; Stefanini, Matteo; Fiori, Roberto; Gandini, Roberto; Bagalà, Paolo; Morosetti, Daniele; Calabria, Eros; Tonnetti, Alessia; Verona-Rinati, Gianluca; Santoni, Riccardo; Simonetti, Giovanni
The purpose of this work has been to dosimetrically investigate four fluoroscopically guided interventions: the percutaneous vertebroplasty (PVP), the percutaneous disc decompression (PDD), the radiofrequency medial branch neurolysis (RF) (hereafter named spine procedures), and the endovascular treatment for the critical limb ischemia (CLI). The X-ray equipment used was a Philips Integris Allura Xper FD20 imaging system provided with a dose-area product (DAP) meter. The parameters investigated were: maximum skin dose (MSD), air kerma (Ka,r), DAP, and fluoroscopy time (FT). In order to measure the maximum skin dose, we employed a system based on MOSFET detectors. Before using the system on patients, a calibration factor Fc and correction factors for energy (CkV) and field size (CFD) dependence were determined. Ka,r, DAP, and FT were extrapolated from the X-ray equipment. The analysis was carried out on 40 patients, 10 for each procedure. The average fluoroscopy time and DAP values were compared with the reference levels (RLs) proposed in literature. Finally, the correlations between MSD, FT, Ka,r, and DAP values, as well as between DAP and FT values, were studied in terms of Pearson's product-moment coefficients for spine procedures only. An Fc value of 0.20 and a very low dependence of CFD on field size were found. A third-order polynomial function was chosen for CkV. The mean values of MSD ranged from 2.3 to 10.8cGy for CLI and PVP, respectively. For these procedures, the DAP and FT values were within the proposed RL values. The statistical analysis showed little correlation between the investigated parameters. The interventional procedures investigated were found to be both safe with regard to deterministic effects and optimized for stochastic ones. In the spine procedures, the observed correlations indicated that the estimation of MSD from Ka,r or DAP was not accurate and a direct measure of MSD is therefore recommended. PMID:25679159
Deuk Laser Disc Repair® is a safe and effective treatment for symptomatic cervical disc disease
Deukmedjian, Ara J.; Jason Cutright, S. T.; Augusto Cianciabella, PA-C; Deukmedjian, Arias
Background: Deuk Laser Disc Repair® is a new full-endoscopic surgical procedure to repair symptomatic cervical disc disease. Methods: A prospective cohort of 66 consecutive patients underwent cervical Deuk Laser Disc Repair® for one (n = 21) or two adjacent (n = 45) symptomatic levels of cervical disc disease and were evaluated postoperatively for resolution of headache, neck pain, arm pain, and radicular symptoms. All patients were candidates for anterior cervical discectomy and fusion (ACDF) or arthroplasty. The Mann–Whitney Wilcoxon test was used to calculate P values. Results: All patients (n = 66) had significant improvement in preoperative symptoms with an average symptom resolution of 94.6%. Fifty percent (n = 33) had 100% resolution of all preoperative cervicogenic symptoms. Only 4.5% (n = 3) had less than 80% resolution of preoperative symptoms. Visual analog scale (VAS) significantly improved from 8.7 preoperatively to 0.5 postoperatively (P < 0.001) for the cohort. Average operative and recovery times were 57 and 52 minutes, respectively. There were no perioperative complications. Recurrent disc herniation occurred in one patient (1.5%). Average postoperative follow-up was 94 days and no significant intergroup difference in outcomes was observed (P = 0.111) in patients with <90 days (n = 52) or >90 days (n = 14, mean 319 days) follow-up. No significant difference in outcomes was observed (P = 0.774) for patients undergoing one or two level Deuk Laser Disc Repair®. Patients diagnosed with postoperative cervical facet syndrome did significantly worse (P < 0.001). Conclusion: Deuk Laser Disc Repair® is a safe and effective alternative to ACDF or arthroplasty for the treatment of one or two adjacent symptomatic cervical disc herniations with an overall success rate of 94.6%. PMID:23776754
Cervical Deuk Laser Disc Repair®: A novel, full-endoscopic surgical technique for the treatment of symptomatic cervical disc disease
Deukmedjian, Ara J.; Cianciabella, Augusto; Cutright, Jason; Deukmedjian, Arias
Background: Cervical Deuk Laser Disc Repair® is a novel full-endoscopic, anterior cervical, trans-discal, motion preserving, laser assisted, nonfusion, outpatient surgical procedure to safely treat symptomatic cervical disc diseases including herniation, spondylosis, stenosis, and annular tears. Here we describe a new endoscopic approach to cervical disc disease that allows direct visualization of the posterior longitudinal ligament, posterior vertebral endplates, annulus, neuroforamina, and herniated disc fragments. All patients treated with Deuk Laser Disc Repair were also candidates for anterior cervical discectomy and fusion (ACDF). Methods: A total of 142 consecutive adult patients with symptomatic cervical disc disease underwent Deuk Laser Disc Repair during a 4-year period. This novel procedure incorporates a full-endoscopic selective partial decompressive discectomy, foraminoplasty, and posterior annular debridement. Postoperative complications and average volume of herniated disc fragments removed are reported. Results: All patients were successfully treated with cervical Deuk Laser Disc Repair. There were no postoperative complications. Average volume of herniated disc material removed was 0.09 ml. Conclusions: Potential benefits of Deuk Laser Disc Repair for symptomatic cervical disc disease include lower cost, smaller incision, nonfusion, preservation of segmental motion, outpatient, faster recovery, less postoperative analgesic use, fewer complications, no hardware failure, no pseudoarthrosis, no postoperative dysphagia, and no increased risk of adjacent segment disease as seen with fusion. PMID:23230523
Percutaneous Disc Decompression with Nucleoplasty–Volumetry of the Nucleus Pulposus Using Ultrahigh-Field MRI
Kasch, Richard; Mensel, Birger; Schmidt, Florian; Drescher, Wolf; Pfuhl, Ralf; Ruetten, Sebastian; Merk, Harry R.; Kayser, Ralph
Purpose To evaluate changes in nucleus pulposus volume as a potential parameter for the effects of disc decompression. Methods Fifty-two discs (T8 to L1) were extracted from 26 pigs and separated into thoracic (T8 to T11) and thoracolumbar discs (T12 to L1). The discs were imaged using 7.1 Tesla ultrahigh-field magnetic resonance imaging (MRI) with acquisition of axial T2-weighted turbo spin-echo sequences for determination of baseline and postinterventional nucleus pulposus volumes. Volumes were calculated using OsiriX® (http://www.osirix-viewer.com). After randomization, one group was treated with nucleoplasty, while the placebo group was treated with an identical procedure but without coblation current. The readers analyzing the MR images were blinded to the kind of procedure performed. Baseline and postinterventional volumes were compared between the nucleoplasty and placebo group. Results Average preinterventional nucleus volume was 0.799 (SD: 0.212) ml. Postinterventional volume reduction in the nucleoplasty group was significant at 0.052 (SD: 0.035) ml or 6.30% (p<0.0001) (thoracic discs) and 0.082 (SD: 0.042) ml or 7.25% (p = 0.0078) (thoracolumbar discs). Nucleoplasty achieved volume reductions of 0.114 (SD: 0.054) ml or 14.72% (thoracic) and 0.093 (SD: 0.081) ml or 11.61% (thoracolumbar) compared with the placebo group. Conclusions Nucleoplasty significantly reduces thoracic and thoracolumbar nucleus pulposus volumes in porcine discs. PMID:22848512
Introduction Herniated lumbar disc is a displacement of disc material (nucleus pulposus or annulus fibrosis) beyond the intervertebral disc space. The highest prevalence is among people aged 30 to 50 years, with a male to female ratio of 2:1. There is little evidence to suggest that drug treatments are effective in treating herniated disc. Methods and outcomes We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of drug treatments, non-drug treatments, and surgery for herniated lumbar disc? We searched: Medline, Embase, The Cochrane Library, and other important databases up to June 2010 (Clinical Evidence reviews are updated periodically; please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA). Results We found 37 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions. Conclusions In this systematic review, we present information relating to the effectiveness and safety of the following interventions: acupuncture, advice to stay active, analgesics, antidepressants, bed rest, corticosteroids (epidural injections), cytokine inhibitors (infliximab), discectomy (automated percutaneous, laser, microdiscectomy, standard), exercise therapy, heat, ice, massage, muscle relaxants, non-steroidal anti-inflammatory drugs (NSAIDs), percutaneous disc decompression, spinal manipulation, and traction. PMID:21711958
Percutaneous bipolar radiofrequency thermocoagulation for the treatment of lumbar disc herniation.
Zeng, Zhenhua; Yan, Min; Dai, Yi; Qiu, Weidong; Deng, Shuo; Gu, Xinzhu
Lumbar disc herniation is usually managed with conservative treatment or surgery. However, conservative therapy seldom yields good results, and surgery is associated with multiple complications. This study aimed to assess bipolar radiofrequency thermocoagulation for the treatment of lumbar disc herniation. A total of 168 patients with lumbar disc herniation suitable for radiofrequency thermocoagulation were enrolled and randomized to monopolar radiofrequency thermocoagulation (control group, n=84) or bipolar radiofrequency thermocoagulation (experimental group, n=84) treatment groups. Ablation sites were targeted under CT scan guidance, and consecutive radiofrequency therapy was used. One and two probes were used for monopolar and bipolar thermocoagulation, respectively. Thermocoagulation was achieved at 50°C, 60°C, and 70°C for 60s each, 80°C for 90s, and 92°C for 100s. Symptoms and complications were evaluated using the modified Macnab criteria and Visual Analog Scale at 7, 30, and 180days postoperatively. At 180days, a significantly higher efficacy rate was obtained in the experimental group compared with control patients (91.6% versus 79.7%, P<0.05). No severe complications were occurred in either group. Targeted ablation via bipolar radiofrequency thermocoagulation is efficient for lumbar disc herniation treatment, and should be further explored for broad clinical application. PMID:27234606
Experimental study using ER-YAG laser in discs: changes in glycosaminoglycan content and synthesis in discs
NASA Astrophysics Data System (ADS)
Maehara, Kazuyuki; Nakai, Sadaaki; Naga, Kumi; Nishimoto, Seiji
Changes in discs after Er-Yag laser irradiation are scarcely reported. We made an experimental study using white rabbits and Er-Yag laser. Under general anesthesia, Er-Yag laser was irradiated into lumbar discs. Three or 8 weeks after irradiation, rabbits were sacrificed, and these discs were extracted. The quantitative analysis of the glycosaminoglycan content in the annulus fibrosus, and the incorporation of 35S-sulfate in chondroitin 4 sulfate were measured. The results showed, the increased incorporation of 35S-sulfate in chondroitin 4 sulfate and chondroitin 6 sulfates in groups of laser irradiation may indicate Er-Yag laser irradiation in nucleus pulposus, accelerated glycosaminoglycan production, in the annulus fibrosus. But no difference of unsaturated isomers of chondroitin 4 sulfate, and chondroitin 6 sulfate, and no difference of saturated isomer of keratan sulfate indicate, the influence of Er-Yag laser irradiation was not so high, as to bring the quantitative changes of matrix of annulus fibrosus in term of 8 weeks.
Long-term outcomes of patients with lumbar disc herniation treated with percutaneous discectomy: comparative study with microendoscopic discectomy.
Liu, Wen-Gui; Wu, Xiao-Tao; Guo, Jin-He; Zhuang, Su-Yang; Teng, Gao-Jun
We assessed the long-term outcomes of patients with lumbar disc herniation treated with percutaneous lumbar discectomy (PLD) or microendoscopic discectomy (MED). A retrospective study was performed in consecutive patients with lumbar disc herniation treated with PLD (n = 129) or MED (n = 101) in a single hospital from January 2000 to March 2002. All patients were followed up with MacNab criteria and self-evaluation questionnaires comprising the Oswestry Disability Index and Medical Outcomes Study 36-Item Short-Form Health Survey. Several statistical methods were used for analyses of the data, and a p value of <0.05 was considered to be statistically significant. A total of 104 patients (80.62%) with PLD and 82 patients (81.19%) with MED were eligible for analyses, with a mean follow-up period of 6.64 +/- 0.67 years and 6.42 +/- 0.51 years, respectively. There were no significant differences between the two groups in age, number of lesions, major symptoms and physical signs, and radiological findings. According to the MacNab criteria, 75.96% in the PLD group and 84.15% in the MED group achieved excellent or good results, respectively, this was statistically significant (p = 0.0402). With the Oswestry Disability Index questionnaires, the average scores and minimal disability, respectively, were 6.97 and 71.15% in the PLD group and 4.89 and 79.27% in the MED group. Total average scores of Medical Outcomes Study 36-Item Short-Form Health Survey were 75.88 vs. 81.86 in PLD group vs. MED group (p = 0.0582). The cost and length of hospitalization were higher or longer in MED group, a statistically significant difference (both p < 0.0001). Long-term complications were observed in two patients (2.44%) in the MED group, no such complications were observed in the PLD group. Both PLD and MED show an acceptable long-term efficacy for treatment of lumbar disc herniation. Compared with MED patients, long-term satisfaction is slightly lower in the PLD patients; complications
Long-Term Outcomes of Patients with Lumbar Disc Herniation Treated with Percutaneous Discectomy: Comparative Study with Microendoscopic Discectomy
Liu Wengui; Wu Xiaotao; Guo Jinhe; Zhuang Suyang; Teng Gaojun
We assessed the long-term outcomes of patients with lumbar disc herniation treated with percutaneous lumbar discectomy (PLD) or microendoscopic discectomy (MED). A retrospective study was performed in consecutive patients with lumbar disc herniation treated with PLD (n = 129) or MED (n = 101) in a single hospital from January 2000 to March 2002. All patients were followed up with MacNab criteria and self-evaluation questionnaires comprising the Oswestry Disability Index and Medical Outcomes Study 36-Item Short-Form Health Survey. Several statistical methods were used for analyses of the data, and a p value of <0.05 was considered to be statistically significant. A total of 104 patients (80.62%) with PLD and 82 patients (81.19%) with MED were eligible for analyses, with a mean follow-up period of 6.64 {+-} 0.67 years and 6.42 {+-} 0.51 years, respectively. There were no significant differences between the two groups in age, number of lesions, major symptoms and physical signs, and radiological findings. According to the MacNab criteria, 75.96% in the PLD group and 84.15% in the MED group achieved excellent or good results, respectively, this was statistically significant (p = 0.0402). With the Oswestry Disability Index questionnaires, the average scores and minimal disability, respectively, were 6.97 and 71.15% in the PLD group and 4.89 and 79.27% in the MED group. Total average scores of Medical Outcomes Study 36-Item Short-Form Health Survey were 75.88 vs. 81.86 in PLD group vs. MED group (p = 0.0582). The cost and length of hospitalization were higher or longer in MED group, a statistically significant difference (both p < 0.0001). Long-term complications were observed in two patients (2.44%) in the MED group, no such complications were observed in the PLD group. Both PLD and MED show an acceptable long-term efficacy for treatment of lumbar disc herniation. Compared with MED patients, long-term satisfaction is slightly lower in the PLD patients; complications
Electronic and thermal lensing in diode end-pumped Yb:YAG laser rods and discs
Antipov, Oleg L; Anashkina, E A; Fedorova, K A
The lensing effects in diode end-pumped Yb:YAG laser rods and discs are studied. Two mechanisms of refractive-index changes are taken into account, thermal and electronic (due to the difference between the excited- and ground-state Yb{sup 3+} polarisabilities), as well as pump-induced deformation of the laser crystal. Under pulsed pumping, the electronic lensing effect prevails over the thermal one in both rods and discs. In rods pumped by a highly focused cw beam, the dioptric power of the electronic lens exceeds that of the thermal lens, whereas in discs steady-state lensing is predominantly due to the thermal mechanism. (active media)
Effect of repetitive laser pulses on the electrical conductivity of intervertebral disc tissue
Omel'chenko, A I; Sobol', E N
The thermomechanical effect of 1.56-{mu}m fibre laser pulses on intervertebral disc cartilage has been studied using ac conductivity measurements with coaxial electrodes integrated with an optical fibre for laser radiation delivery to the tissue. The observed time dependences of tissue conductivity can be interpreted in terms of hydraulic effects and thermomechanical changes in tissue structure. The laserinduced changes in the electrical parameters of the tissue are shown to correlate with the structural changes, which were visualised using shadowgraph imaging. Local ac conductivity measurements in the bulk of tissue can be used to develop a diagnostic/monitoring system for laser regeneration of intervertebral discs. (laser biology and medicine)
Outcomes of Microendoscopic Discectomy and Percutaneous Transforaminal Endoscopic Discectomy for the Treatment of Lumbar Disc Herniation: A Comparative Retrospective Study
Sinkemani, Arjun; Hong, Xin; Gao, Zeng-Xin; Zhuang, Su-Yang; Jiang, Zan-Li; Zhang, Shao-Dong; Bao, Jun-Ping; Zhu, Lei; Zhang, Pei; Xie, Xin-Hui; Wang, Feng
Study Design Retrospective, case control evaluation of 86 patients who underwent microendoscopic discectomy (MED) and percutaneous transforaminal endoscopic discectomy (PTED) for the treatment of lumbar disc herniation (LDH). Purpose To evaluate the safety and the outcomes of MED and PTED for the treatment of LDH. Overview of Literature MED and PTED are minimally invasive surgical techniques for lower back pain. Studies to date have shown that MED and PTED are safe and effective treatment modalities for LDH. Methods A retrospective study was performed in patients with LDH treated with MED (n=50) and transforaminal endoscopic discectomy (PTED; n=36) in our hospital. All patients were followed-up with self-evaluation questionnaires, Oswestry disability index (ODI), medical outcomes study 36-item short form health survey and MacNab criteria. All the patients in both groups were followed up to 12 months after the operation. Results ODI questionnaire responses were not statistically different between the MED and PTED groups (53.00 vs. 48.72) before treatment. Average scores and minimal disability after 5 days to 12 months of follow-up were 4.96 in the MED group and 3.61 in the PTED group. According to MacNab criteria, 92.0% of the MED group and 94.4% of the PTED group had excellent or good results with no significant difference. Conclusions There was no significant difference between MED and PTED outcomes. Further large-scale, randomized studies with long-term follow-up are needed. PMID:26713113
The Factors Associated With the Successful Outcomes of Percutaneous Disc Decompression in Patients With Lumbar Herniated Nucleus Pulposus
Lee, Sang Heon; Kim, Nack Hwan; Park, Hyeun Jun; Yoo, Hyun-Joon; Jo, Soo Yung
Objective To determine clinical and radiological factors that predict the successful outcome of percutaneous disc decompression (PDD) in patients with lumbar herniated nucleus pulposus (HNP). Methods We retrospectively reviewed the clinical and radiological features of patients who underwent lumbar PDD from April 2009 to March 2013. Sixty-nine patients with lumbar HNP were studied. Clinical outcome was assessed by the visual analogue scale (VAS) and the Oswestry Disability Index (ODI). Multivariate logistic regression analysis was performed to assess relationship among clinical and radiological factors and the successful outcome of the PDD. Results The VAS and the ODI decreased significantly at 1 year follow-up (p<0.01). One year after PDD, the reduction of the VAS (ΔVAS) was significantly greater in the patients with pain for <6 months (p=0.03) and subarticular HNP (p=0.015). The reduction of the ODI (ΔODI) was significantly greater in the patients with high intensity zone (p=0.04). Multivariate logistic regression analysis revealed the following 5 factors that were associated with the successful outcome after PDD: pain duration for <6 months (odds ratio [OR]=14.036; p=0.006), positive straight leg raising test (OR=8.425, p=0.014), the extruded HNP (OR=0.106, p=0.04), the sequestrated HNP (OR=0.037, p=0.026), and the subarticular HNP (OR=10.876, p=0.012). Conclusion PDD provided significant improvement of pain and disability of patients. The results of the analysis indicated that the duration of pain <6 months, positive straight leg raising test, the subarticular HNP, and the protruded HNP were predicting factors associated with the successful response of PDD in patients with lumbar HNP. PMID:26605171
LASER BIOLOGY AND MEDICINE: Effect of repetitive laser pulses on the electrical conductivity of intervertebral disc tissue
NASA Astrophysics Data System (ADS)
Omel'chenko, A. I.; Sobol', E. N.
The thermomechanical effect of 1.56-μm fibre laser pulses on intervertebral disc cartilage has been studied using ac conductivity measurements with coaxial electrodes integrated with an optical fibre for laser radiation delivery to the tissue. The observed time dependences of tissue conductivity can be interpreted in terms of hydraulic effects and thermomechanical changes in tissue structure. The laserinduced changes in the electrical parameters of the tissue are shown to correlate with the structural changes, which were visualised using shadowgraph imaging. Local ac conductivity measurements in the bulk of tissue can be used to develop a diagnostic/monitoring system for laser regeneration of intervertebral discs.
Treatment of Kidney Stone in a Kidney-Transplanted Patient with Mini-Percutaneous Laser Lithotripsy: A Case Report
Markić, Dean; Krpina, Kristian; Ahel, Juraj; Gršković, Antun; Španjol, Josip; Rubinić, Nino; Materljan, Mauro; Mikolašević, Ivana; Orlić, Lidija; Rački, Sanjin
We report a case of a kidney-transplanted patient with urolithiasis treated with mini-percutaneous laser lithotripsy. The patient presented with renal dysfunction and graft hydronephrosis. Diagnostic procedures revealed ureterolithiasis as a cause of obstruction, and percutaneous nephrostomy was inserted as a temporary solution. Before surgery, the stone migrated to the renal pelvis. Mini-percutaneous laser lithotripsy was successfully performed, and during surgery, all stone fragments were removed. Six months after successful treatment, the patient has good functioning and stone-free graft. PMID:27066492
Regeneration of spine disc and joint cartilages under temporal and space modulated laser radiation
NASA Astrophysics Data System (ADS)
Sobol, E.; Shekhter, A.; Baskov, A.; Baskov, V.; Baum, O.; Borchshenko, I.; Golubev, V.; Guller, A.; Kolyshev, I.; Omeltchenko, A.; Sviridov, A.; Zakharkina, O.
The effect of laser radiation on the generation of hyaline cartilage in spine disc and joints has been demonstrated. The paper considers physical processes and mechanisms of laser regeneration, presents results of investigations aimed to optimize laser settings and to develop feedback control system for laser reconstruction of spine discs. Possible mechanisms of laser-induced regeneration include: (1) Space and temporary modulated laser beam induces nonhomogeneous and pulse repetitive thermal expansion and stress in the irradiated zone of cartilage. Mechanical effect due to controllable thermal expansion of the tissue and micro and nano gas bubbles formation in the course of the moderate (up to 45-50 oC) heating of the NP activate biological cells (chondrocytes) and promote cartilage regeneration. (2) Nondestructive laser radiation leads to the formation of nano and micro-pores in cartilage matrix. That promotes water permeability and increases the feeding of biological cells. Results provide the scientific and engineering basis for the novel low-invasive laser procedures to be used in orthopedics for the treatment cartilages of spine and joints. The technology and equipment for laser reconstruction of spine discs have been tested first on animals, and then in a clinical trial. Since 2001 the laser reconstruction of intervertebral discs have been performed for 340 patients with chronic symptoms of low back or neck pain who failed to improve with non-operative care. Substantial relief of back pain was obtained in 90% of patients treated who returned to their daily activities. The experiments on reparation of the defects in articular cartilage of the porcine joints under temporal and spase modulated laser radiation have shown promising results.
Percutaneous peripheral laser angioplasty with a pulsed Nd:YAG laser and sapphire tips
NASA Astrophysics Data System (ADS)
Kvasnicka, Jan; Stanek, Frantisek; Boudik, Frantisek; Kubecek, Vaclav; Krivanek, Jiri; Keclik, Richard; Prochazkova, Helena; Hamal, Karel
Percutaneous transluminal laser angioplasty with a pulsed Nd:YAG laser (1,064 nm wavelength, 100 jig pulse duration, up to 0.4 J per pulse, 10 Hz repetition rate) coupled to optical fibers with sapphire tips of 1.8, 2.2 and 2.9 mm diameter was performed in 17 chronic occlusions of iliac, femoral, popliteal and fibular arteries in 15 patients. Clinically the procedure was successful in 14 cases. The probe formed a primary channel of at least 2.0 mm width which was further dilated by conventional balloon catheter. Ankle/brachial systolic pressure index (ABPI) increased from 0.46 0.13 to 0.84 0.21 after the procedure. Two failures were due to an extensive dissection which occurred after balloon angioplasty and resulted in an early reocclusion. In the remaining case a balloon catheter could not be introduced through the 30 cm long primary channel which reoccluded shortly after the recanalization. The initial patency rate was 82 % and in 5 patients followed for more then 6 months the ABPI showed only a minor decrease. These first results are encouraging and it is likely that this method could become an important alternative to conventional balloon angioplasty.
CD, DVD, and Blu-Ray Disc Diffraction with a Laser Ray Box
NASA Astrophysics Data System (ADS)
DeWeerd, Alan J.
A compact disc (CD) can be used as a diffraction grating, even though its track consists of a series of pits, not a continuous groove. Previous authors described how to measure the track spacing on a CD using an incident laser beam normal to the surface or one at an oblique angle. In both cases, the diffraction pattern was projected on a screen and distance measurements allowed the track spacing to be calculated. I propose an alternative method using a laser ray box, which is also applied to a DVD and a Blu-ray disc.
CD, DVD, and Blu-Ray Disc Diffraction with a Laser Ray Box
ERIC Educational Resources Information Center
DeWeerd, Alan J.
A compact disc (CD) can be used as a diffraction grating, even though its track consists of a series of pits, not a continuous groove. Previous authors described how to measure the track spacing on a CD using an incident laser beam normal to the surface or one at an oblique angle. In both cases, the diffraction pattern was projected on a screen…
Percutaneous Endoscopic Holmium Laser Lithotripsy for Management of Complicated Biliary Calculi
Healy, Kelly; Chamsuddin, Abbas; Spivey, James; Martin, Louis; Nieh, Peter
Background and Objectives: Advances in endoscopic techniques have transformed the management of urolithiasis. We sought to evaluate the role of such urological interventions for the treatment of complex biliary calculi. Methods: We conducted a retrospective review of all patients (n=9) undergoing percutaneous holmium laser lithotripsy for complicated biliary calculi over a 4-year period (12/2003 to 12/2007). All previously failed standard techniques include ERCP with sphincterotomy (n=6), PTHC (n=7), or both of these. Access to the biliary system was obtained via an existing percutaneous transhepatic catheter or T-tube tracts. Endoscopic holmium laser lithotripsy was performed via a flexible cystoscope or ureteroscope. Stone clearance was confirmed intra- and postoperatively. A percutaneous transhepatic drain was left indwelling for follow-up imaging. Results: Mean patient age was 65.6 years (range, 38 to 92). Total stone burden ranged from 1.7 cm to 5 cm. All 9 patients had stones located in the CBD, with 2 patients also having additional stones within the hepatic ducts. All 9 patients (100%) were visually stone-free after one endoscopic procedure. No major perioperative complications occurred. Mean length of stay was 2.4 days. At a mean radiological follow-up of 5.4 months (range, 0.5 to 21), no stone recurrence was noted. Conclusions: Percutaneous endoscopic holmium laser lithotripsy is a minimally invasive alternative to open salvage surgery for complex biliary calculi refractory to standard approaches. This treatment is both safe and efficacious. Success depends on a multidisciplinary approach. PMID:19660213
Efficiency of disc ablation with lasers of various wavelengths.
Choy, D S; Altman, P; Trokel, S L
In testing the CO2 lasers in CW and pulse mode, the erbium:YAG, the Nd:YAG 1318 microns and 1064 microns, the argon, the holmium:YAG, and the excimer, we found the greatest efficiency in the CO2 CW and pulse mode, and the lowest efficiency in the argon. Data with the holmium:YAG were unreliable because of the early generation laser tested. The Nd:YAG was second only to the CO2 laser, and because the latter has no waveguide, we deemed the Nd:YAG the laser of choice for PLDD. PMID:10150639
Optical methods for diagnostics and feedback control in laser-induced regeneration of spine disc and joint cartilages
NASA Astrophysics Data System (ADS)
Sobol, Emil; Sviridov, Alexander; Omeltchenko, Alexander; Baum, Olga; Baskov, Andrey; Borchshenko, Igor; Golubev, Vladimir; Baskov, Vladimir
In 1999 we have introduced a new approach for treatment of spine diseases based on the mechanical effect of nondestructive laser radiation on the nucleus pulposus of the intervertebral disc. Laser reconstruction of spine discs (LRD) involves puncture of the disc and non-destructive laser irradiation of the nucleus pulposus to activate reparative processes in the disc tissues. In vivo animal study has shown that LRD allows activate the growth of hyaline type cartilage in laser affected zone. The paper considers physical processes and mechanisms of laser regeneration, presents results of investigations aimed to optimize laser settings and to develop feedback control system for laser reparation in cartilages of spine and joints. The results of laser reconstruction of intervertebral discs for 510 patients have shown substantial relief of back pain for 90% of patients. Laser technology has been experimentally tested for reparation of traumatic and degenerative diseases in joint cartilage of 20 minipigs. It is shown that laser regeneration of cartilage allows feeling large (more than 5 mm) defects which usually never repair on one's own. Optical techniques have been used to promote safety and efficacy of the laser procedures.
Quantitative Discomanometry: Correlation of Intradiscal Pressure Values to Pain Reduction in Patients With Intervertebral Disc Herniation Treated With Percutaneous, Minimally Invasive, Image-Guided Techniques
Filippiadis, Dimitrios K. Mazioti, A. Papakonstantinou, O. Brountzos, E.; Gouliamos, A.; Kelekis, N. Kelekis, A.
Purpose: To illustrate quantitative discomanometry's (QD) diagnostic efficacy and predictive value in discogenic-pain evaluation in a prospective study correlating intradiscal pressure values with pain reduction after percutaneous image-guided technique (i.e., percutaneous decompression, PD). Materials and Methods: During the last 3 years, 36 patients [21 male and 15 female (mean age 36 {+-} 5.8 years)] with intervertebral disc hernia underwent QD before PD. Under absolute sterilization and fluoroscopy, a mixture of contrast medium and normal saline (3:1 ratio) was injected. A discmonitor performed a constant rate injection and recorded pressure and volume values, thus producing the relative pressure-volume curve. PD was then performed. Pain reduction and improved mobility were recorded at 3, 12, and 24 months after PD using clinical evaluation and a numeric visual scale (NVS; 0 to 10 units). Results: Mean pain values of 7.5 {+-} 1.9 (range 4 to 8) NVS units were recorded before PD; these decreased to 2.9 {+-} 2.44 at 3 months, 1.0 {+-} 1.9 at 12 months, and 1.0 {+-} 1.9 NVS units at 24 months after PD. Recorded correlations (pressure, volume, significant pain-reduction values) with bilateral statistical significance included a maximum injected volume of 2.4 ml (p = 0.045), P{sub o} < 14 psi [initial pressure required to inject 0.1 ml of the mixture inside the disc (p = 0.05)], P{sub max} {<=} 65 psi [greatest pressure value on the curve (p = 0.018)], and P{sub max} - P{sub o} {<=} 47 psi (p = 0.038). Patients meeting these pressure or volume cut-off points, either independently or as a total, had significant pain reduction (>4 NVS units) after PD. No complications were noted. Conclusions: QD is an efficient technique that may have predictive value for discogenic pain evaluation. It might serve as a useful tool for patient selection for intervertebral disc therapies.
[Percutaneous transluminal laser angioplasty in peripheral arterial occlusive disease--development of a new laser catheter system].
Neubaur, T; Klepzig, M; Strauer, B E
Percutaneous laser angioplasty in arterial occlusive disease has lately been performed clinically for the first time. Perforation of the arterial wall and formation of aneurysms are serious risks. Two novel laser catheters for laser angioplasty with minimized perforation risk are presented. Catheter I (5F) and II (6.3F) are designed in the same manner. The distal tip of these catheters is ovally formed and marked by a small X-ray dense metal ring. The silica fiber has a core diameter of 400 micron (I) respectively 600 micron (II). Its tip is also marked X-ray densely and therefore the position of the fiber tip can be controlled exactly during laser angioplasty. Using a guide wire and applicating short laser pulses the perforation risk can be minimized. In a total of 132 atherosclerotic stenosed or obstructed human arteries laser angioplasty was performed in vitro using a Nd:YAG laser. There were two perforations (1.5%). The degree of stenosis was reduced from 87 (90)% to 54 (52)%. Using the 600-micron-fiber (catheter II) the velocity of laser angioplasty was increased 2.5 times compared to laser angioplasty using the 400-micron-fiber. PMID:2968724
ACTIVE MEDIA: Electronic and thermal lensing in diode end-pumped Yb:YAG laser rods and discs
NASA Astrophysics Data System (ADS)
Antipov, Oleg L.; Anashkina, E. A.; Fedorova, K. A.
The lensing effects in diode end-pumped Yb:YAG laser rods and discs are studied. Two mechanisms of refractive-index changes are taken into account, thermal and electronic (due to the difference between the excited- and ground-state Yb3+ polarisabilities), as well as pump-induced deformation of the laser crystal. Under pulsed pumping, the electronic lensing effect prevails over the thermal one in both rods and discs. In rods pumped by a highly focused cw beam, the dioptric power of the electronic lens exceeds that of the thermal lens, whereas in discs steady-state lensing is predominantly due to the thermal mechanism.
[Percutaneous coronary Excimer laser angioplasty in patients with coronary heart disease].
Karsch, K R; Haase, K K; Mauser, M; Ickrath, O; Voelker, W; Baumbach, A; Seipel, L
To verify the efficacy and safety of percutaneous coronary excimer laser angioplasty in patients with coronary artery disease a prospective study was conducted in 60 patients. The application of laser light was possible in 55 of the 60 patients. A novel 1.4-mm diameter catheter with 20 quartz fibers of 100-microns diameter, each arranged concentrically around a central lumen suitable for an 0.014-inch flexible guide wire was used. The light source was a commercial excimer laser emitting energy at a wavelength of 308 nm, with a pulse duration of 60 ns. The laser was operated at 20 Hz; mean energy transmission was 30 +/- 5 mJ/mm2. In 23 of the 55 patients treated with excimer laser energy the qualitative angiographic results were sufficient. In 32 patients additional balloon angioplasty was necessary, either because of an insufficient result or due to vessel closure after laser ablation. In 47 of the 55 patients control angiography was performed within the 6-month follow-up period. Rate of restenosis was higher in patients treated with laser ablation and subsequent balloon angioplasty (16 of 28) than in patients treated with laser ablation alone (6 of 19). Results of the 6-month observation period suggest that 1) coronary excimer laser angioplasty in combination with subsequent balloon angioplasty results in a considerable increase of the restenosis rate; 2) the exclusive use of laser ablation also results in a restenosis rate comparable to balloon angioplasty alone; and 3) the impact of this new method using improved application systems and higher energy transmission has to be determined in further studies. PMID:2399764
Development of kW class Nd:YAG composite ceramic thin disc laser
NASA Astrophysics Data System (ADS)
Iyama, K.; Bhushan, R.; Furukawa, H.; Tsubakimoto, K.; Yoshida, H.; Fujita, H.; Fujita, M.; Miyanaga, N.; Tamaoki, Y.; Kato, Y.; Kawashima, T.
We are developing a high-repetition and high-average-power Nd:YAG laser amplifier pumped by fiber coupled LDs in order to apply to laser machining of carbon composite materials such as CFRP (Carbon Fiber Reinforced Plastic). Final target is 1.5 kW output at wavelength of 1064 nm by 8 kW LD pumping. The amplifier consists of several Nd:YAG ceramic thin discs on a non-doped ceramic YAG block. At first, we measured wave-front distortion and small-signal gain of a prototype amplifier whose target is more than 500 W output.
Percutaneous yttrium aluminum garnet-laser lithotripsy of intrahepatic stones and casts after liver transplantation.
Schlesinger, Nis Hallundbaek; Svenningsen, Peter; Frevert, Susanne; Wettergren, André; Hillingsø, Jens
Bile duct stones and casts (BDSs) contribute importantly to morbidity after liver transplantation (LT). The purpose of this study was to estimate the clinical efficacy, safety, and long-term results of percutaneous transhepatic cholangioscopic lithotripsy (PTCSL) in transplant recipients and to discuss underlying factors affecting the outcome. A retrospective chart review revealed 18 recipients with BDSs treated by PTCSL laser lithotripsy with a holmium-yttrium aluminum garnet laser probe at 365 to 550 µm. They were analyzed in a median follow-up time of 55 months. In all but 1 patient (17/18 or 94%), it was technically feasible to clear all BDSs with a mean of 1.3 sessions. PTCSL was unsuccessful in 1 patient because of multiple stones impacting the bile ducts bilaterally; 17% had early complications (Clavien II). All biliary casts were successfully cleared; 39% had total remission; 61% needed additional interventions in the form of percutaneous transhepatic cholangiography and dilation (17%), re-PTCSL (11%), self-expandable metallic stents (22%), or hepaticojejunostomy (6%); and 22% eventually underwent retransplantation. The overall liver graft survival rate was 78%. Two patients died during follow-up for reasons not related to their BDS. Nonanastomotic strictures (NASs) were significantly associated with treatment failure. We conclude that PTCSL in LT patients is safe and feasible. NASs significantly increased the risk of relapse. Repeated minimally invasive treatments, however, prevented graft failure in 78% of the cases. PMID:25821134
Percutaneous Transcatheter One-Step Mechanical Aortic Disc Valve Prosthesis Implantation: A Preliminary Feasibility Study in Swine
Sochman, Jan Peregrin, Jan H.; Rocek, Miloslav; Timmermans, Hans A.; Pavcnik, Dusan; Roesch, Josef
Purpose. To evaluate the feasibility of one-step implantation of a new type of stent-based mechanical aortic disc valve prosthesis (MADVP) above and across the native aortic valve and its short-term function in swine with both functional and dysfunctional native valves. Methods. The MADVP consisted of a folding disc valve made of silicone elastomer attached to either a nitinol Z-stent (Z model) or a nitinol cross-braided stent (SX model). Implantation of 10 MADVPs (6 Z and 4 SX models) was attempted in 10 swine: 4 (2 Z and 2 SX models) with a functional native valve and 6 (4 Z and 2 SX models) with aortic regurgitation induced either by intentional valve injury or by MADVP placement across the native valve. MADVP function was observed for up to 3 hr after implantation. Results. MADVP implantation was successful in 9 swine. One animal died of induced massive regurgitation prior to implantation. Four MADVPs implanted above functioning native valves exhibited good function. In 5 swine with regurgitation, MADVP implantation corrected the induced native valve dysfunction and the device's continuous good function was observed in 4 animals. One MADVP (SX model) placed across native valve gradually migrated into the left ventricle. Conclusion. The tested MADVP can be implanted above and across the native valve in a one-step procedure and can replace the function of the regurgitating native valve. Further technical development and testing are warranted, preferably with a manufactured MADVP.
Percutaneous laser disk decompression under CT and fluoroscopic guidance: indications, technique, and clinical experience.
Gangi, A; Dietemann, J L; Ide, C; Brunner, P; Klinkert, A; Warter, J M
The aim of percutaneous laser disk decompression (PLDD) is to vaporize a small portion of the nucleus pulposus of an intervertebral disk, thereby reducing the volume and pressure of a diseased disk. This minimally invasive technique can be performed in patients who need surgical intervention for disk herniation with leg pain. PLDD is usually performed under fluoroscopic guidance with or without diskoscopy. However, it can also be performed under dual computed tomographic (CT) and fluoroscopic guidance as an outpatient procedure. CT and fluoroscopic guidance increases the safety and accuracy of PLDD, with high precision of instrument guidance, direct visualization of nucleus pulposus vaporization, and reduced risk of complications. Of 119 patients with lumbar disk herniation treated with PLDD under CT and fluoroscopic guidance, 91 (76.5%) had a good or fair response. PLDD performed with CT and fluoroscopic guidance appears to be a safe and effective treatment for herniated intervertebral disks. PMID:10946692
Percutaneous Transhepatic Endoscopic Holmium Laser Lithotripsy for Intrahepatic and Choledochal Biliary Stones
Rimon, Uri; Kleinmann, Nir; Bensaid, Paul; Golan, Gil; Garniek, Alexander; Khaitovich, Boris; Winkler, Harry
Purpose: To report our approach for treating complicated biliary calculi by percutaneous transhepatic endoscopic biliary holmium laser lithotripsy (PTBL). Patients and Methods: Twenty-two symptomatic patients (11 men and 11 women, age range 51 to 88 years) with intrahepatic or common bile duct calculi underwent PTBL. Nine patients had undergone previous gastrectomy and small-bowel anastomosis, thus precluding endoscopic retrograde cholangiopancreatography. In the other 13 patients, stone removal attempts by ERCP failed due to failed access or very large calculi. We used a 7.5F flexible ureteroscope and a 200-{mu}m holmium laser fiber by way of a percutaneous transhepatic tract, with graded fluoroscopy, to fragment the calculi with direct vision. Balloon dilatation was added when a stricture was seen. The procedure was performed with the patient under general anaesthesia. A biliary drainage tube was left at the end of the procedure. Results: All stones were completely fragmented and flushed into the small bowel under direct vision except for one patient in whom the procedure was aborted. In 18 patients, 1 session sufficed, and in 3 patients, 2 sessions were needed. In 7 patients, balloon dilatation was performed for benign stricture after Whipple operation (n = 3), for choledochalenteric anastomosis (n = 3), and for recurrent cholangitis (n = 1). Adjunctive 'balloon push' (n = 4) and 'rendezvous' (n = 1) procedures were needed to completely clean the biliary tree. None of these patients needed surgery. Conclusion: Complicated or large biliary calculi can be treated successfully using PTBL. We suggest that this approach should become the first choice of treatment before laparoscopic or open surgery is considered.
A Study on the Read/Write Experimental Results for a High-Definition Digital Video Disc Recorder using Blue-Laser Diode
NASA Astrophysics Data System (ADS)
Aoki, Ikuo
At present, tape media are mainly used for video recording globally. However, in the near future, disc media will come into general use, as they possess many strong points compared with tape media. Thus, we are now researching the development of a high-definition digital video disc recorder with high capacity, high data transfer rate, and low cost. Our target specifications are 15 GB to 18 GB, and over 35 Mbps, using a 120 mm phase change disc and a blue-laser diode. To confirm that it is possible, numerous sample discs were manufactured and experiments were carried out. We succeeded in obtaining good experimental results. In this study, we demonstrate the possibility of realizing a high-definition digital video disc recorder using a 120 mm phase change disc and a blue-laser diode without using a disc cartridge or any extraordinary method that increases the cost.
A Comparison of the Effectiveness of Interactive Laser Disc and Classroom Video Tape for Safety Instruction of General Motors Workers.
ERIC Educational Resources Information Center
Bosco, James; Wagner, Jerry
Describes evaluation that assessed the effectiveness of the Interactive Laser Disc System (ILDS) Training Program in comparison with classroom instruction with videotape for training of General Motors workers. Topics discussed include achievement test, attitude scales, opinion surveys, user preference questionnaires, interviews, and variables that…
Comparison between surgical and standing percutaneous contact Nd:YAG laser periosteal transection for potential treatment of equine limb deformities
NASA Astrophysics Data System (ADS)
Tate, Lloyd P.; Baines, Steven J.; Meuten, Donald J.; Stefanacci, J.
Medial and lateral aspects of both radiuses were subjected to periosteal transection of nine healthy equine foals. One site per foal was subjected to surgical periosteal transection and elevation under general anesthesia. The remaining three sites of each foal after injection of a local anesthetic received Nd:YAG contact percutaneous periosteal transection. All radiuses were evaluated radiographically prior to periosteal transection and immediately prior to euthanasia. Foals were euthanized at 3 days, 31 to 34 days, and 67 days post-periosteal transection and gross postmortem and histologic examination performed on each site. Radiographically, periosteal proliferation occurred at all the conventional surgery sites and a majority of the percutaneous laser sites by 30 days post-treatment and was present at 67 days. No limb angulations were noted to occur in any of the foals. The conclusion of the study was that Nd:YAG percutaneous laser periosteal transection was successful in producing periosteal obliteration but with a different histologic appearance than that produced by conventional surgery.
Transarticular Laser Discal Fragmentectomy. A New Minimally Invasive Surgical Approach for Challenging Disc Herniations in the Elderly
Bonaldi, Giuseppe; Brembilla, Carlo; Foresti, Camillo; Cianfoni, Alessandro
Summary This report describes two elderly patients with large disc fragments extruded into lumbar radicular recesses not treatable by any conventional conservative, minimally invasive or surgical approach. Direct access to the disc fragments was obtained crossing the articular zygapophyseal cavity instead of the interlaminar space and spinal canal, using a small needle through which a laser fibre was inserted to deliver energy for tissue ablation. The procedures obtained regression of both symptoms and the bulk of the fragments at early and late clinical and MR follow-ups. PMID:25363258
Laser Interferometer Space Antenna double black holes: dynamics in gaseous nuclear discs
NASA Astrophysics Data System (ADS)
Dotti, Massimo; Colpi, Monica; Haardt, Francesco
We study the inspiral of double black holes, with masses in the Laser Interferometer Space Antenna (LISA) window of detectability, orbiting inside a massive circumnuclear, rotationally supported gaseous disc. Using high-resolution smoothed particle hydrodynamics simulations, we follow the black hole dynamics in the early phase when gas-dynamical friction acts on the black holes individually, and continue our simulation until they form a close binary. We find that in the early sinking the black holes lose memory of their initial orbital eccentricity if they corotate with the gaseous disc. As a consequence, the massive black holes bind forming a binary with a low eccentricity, consistent with zero within our numerical resolution limit. The cause of circularization resides in the rotation present in the gaseous background where dynamical friction operates. Circularization may hinder gravitational waves from taking over and leading the binary to coalescence. In the case of counter-rotating orbits, the initial eccentricity (if present) does not decrease, and the black holes may bind forming an eccentric binary. When dynamical friction has subsided, for equal mass black holes and regardless their initial eccentricity, angular momentum loss, driven by the gravitational torque exerted on the binary by surrounding gas, is nevertheless observable down to the smallest scale probed (~=1 pc). In the case of unequal masses, dynamical friction remains efficient down to our resolution limit, and there is no sign of formation of any ellipsoidal gas distribution that may further harden the binary. During inspiral, gravitational capture of gas by the black holes occurs mainly along circular orbits; eccentric orbits imply high relative velocities and weak gravitational focusing. Thus, the active galactic nucleus activity may be excited during the black hole pairing process and double active nuclei may form when circularization is completed, on distance scales of tens of parsecs.
Echocardiography-guided percutaneous per-ventricular laser ablation of ventricular septum: in vivo study in a canine model.
He, Guangbin; Sun, Chao; Zhang, Xiangkong; Zuo, Lei; Qin, Haiying; Zheng, Minjuan; Zhou, Xiaodong; Liu, Liwen
Surgical myectomy and ethanol ablation are established intervention strategies for left ventricular outflow obstruction in hypertrophic cardiomyopathy. Safety and efficacy limitations of these interventions call for a minimally invasive, potentially safer, and more efficacious strategy. In this study, we aimed to evaluate the feasibility of echocardiography-guided percutaneous per-ventricular laser ablation of a ventricular septum in a canine model. Six domestic dogs were chosen for the study. A 21G needle was inserted into the right ventricle with its tip reaching the targeted basal to mid-septum, after which laser ablation was performed as follows: 1-W laser for 3 min (180 J) at the basal segment and 5 min (300 J) at middle segment of the septum, respectively. Echocardiography, blood chemistry tests, and pathology examination were performed to assess the results of laser ablation. No death or major complications, i.e., tamponade, pericardial effusion, or ventricular fibrillation, occurred. The laser-ablated areas were well demarcated in the results of the pathological examination. The diameters of the ablated regions were 4.42 ± 0.57 and 5.28 ± 0.83 mm for 3 and 5 min ablation, respectively. Pre-ablation and post-ablation, cardiac enzymes were found to increase significantly while no significant differences were found among M-mode, 2D (LVEF), pulsed-wave (PW) Doppler, and tissue Doppler imaging (TDI) measurements. Contrast echocardiography confirmed the perfusion defects in the ablated regions. Microscopically, the ablated myocardium showed coagulative changes and a sparse distribution of disappearing nuclei and an increase in eosinophil number were observed. Our study suggests that percutaneous and per-ventricular laser ablation of the septum is feasible, potentially safe and efficacious, and warrants further investigation and validation. PMID:26861985
[Minimally invasive surgery in treatment of lumbar intervertebral disc herniation].
Rotim, Krešimir; Sajko, Tomislav; Borić, Marta; Subašić, Ante
Surgical treatment of lumbar intervertebral disc herniation is one of the most common neurosurgical procedures. Besides conventional surgical techniques, in the last more than 30 years, different methods with minimal damage to neuromuscular spine structures are being developed and introduced, all having the purpose of reducing postoperative back pain. The advantages of the minimally invasive spine surgery include: possibility of performing procedures under local anaesthesia, reduced hospital stay, limited blood loss with consecutively reduced fibrous tissue development. Patients are capable of return to work and everyday activities early after surgery. From the economical point of view, this kind of treatment is considered to be a cost-effective intervention. Three methods that are being used for treatment of lumbar intervertebral disc herniation are: percutaneous laser disc decompression (PLDD), microdiscectomy using tubular retractor system and selective endoscopic discectomy (SED). Conducted prospective studies have shown that minimally invasive methods are adequate alternative to classic surgical procedures. PMID:26065287
Comparison of open surgical discectomy versus plasma-laser nucleoplasty in patients with single lumbar disc herniation
Abrishamkar, Saeid; Kouchakzadeh, Masih; Mirhosseini, Ahmad; Tabesh, Homayoun; Rezvani, Majid; Moayednia, Amir; Ganjeifar, Babak; Mahabadi, Amir; Yousefi, Elham; Kooshki, Ali Mehrabi
Background: Intervertebral disc herniation is a major cause of low back pain. Several treatment methods are available for lumbar disc herniation including Chemonucleolysis, open surgery, nucleoplasty, laser disc decompression, and intradiscal electrothermal therapy. The high prevalence of lumbar disc herniation necessitates a minimally invasive yet effective treatment method. In this study, we compared the outcomes of open surgery and nucleoplasty method in patients with single lumbar disc herniation. Materials and Methods: This study was a noninferiority randomized clinical trial conducted in one of the University Hospitals of Isfahan Medical University; The Alzahra Hospital. About 200 patients with the diagnosis of lumbar disc herniation were recruited and were assigned to either the treatment or control groups using block randomization. One group received open surgery and the other group received nucleoplasty as the method of treatment. Patients were revisited at 14 days, 1, 2, 3 months, and 1-year after surgery and were assessed for the following variables: Lower back pain, lower limb pain, common complications of surgery (e.g., discitis, infection and hematoma) and recurrence of herniation. Results: The mean (standard deviation) severity of low back pain was reduced from 6.92 (2.5) to 3.43 (2.3) in the nucleoplasty group (P = 0.04) and from 7.5 (2.2) to 3.04 (1.61) in the discectomy group (P = 0.73). Between group difference was not statistically significant (P = 0.44), however, time and treatment interaction was significant (P = 0.001). The level of radicular pain evaluated 1 year after treatment was reduced from 8.1 (1.2) to 2.9 (1.2) (P = 0.004) and from 7.89 (2.1) to 3.6 (2.5) (P =0.04) in the discectomy and the nucleoplasty groups respectively, significant interaction between time and treatment options was observed (P < 0.001) while there was no significant difference between two treatment groups (P = 0.82). Conclusion: Our results show that while
Percutaneous transluminal laser guide wire recanalization of chronic subclavian artery occlusion in symptomatic coronary-subclavian steal syndrome.
Eggebrecht, H; Naber, C K; Oldenburg, O; Herrmann, J; Haude, M; Erbel, R; Baumgart, D
Treatment of subclavian artery stenosis by percutaneous balloon angioplasty and adjunctive stent placement was shown to be safe and efficacious, but it may be limited in tight stenoses and long occlusions. We describe the case of a patient who experienced progressive angina pectoris associated with signs of cerebrovertebral insufficiency 9 yr after bypass surgery, including left internal mammary artery (LIMA) grafting to the left anterior descending coronary artery. Angiography showed reversed flow through the LIMA graft into the subclavian artery and a 4-cm occlusion beginning at the origin of the left subclavian artery, representing a rare coronary-subclavian steal syndrome. After a conventional approach failed, recanalization was performed successfully using laser guide wire angioplasty with adjunctive stent placement in a combined radial and femoral approach. PMID:11108691
Laparoscopic-assisted mini percutaneous nephrolithotomy in the ectopic pelvic kidney: Outcomes with the laser dusting technique
D'souza, Nischith; Verma, Ashish; Rai, Avinash
Introduction: The treatment of renal lithiasis has undergone a sea change with the advent of extracorporeal shock wave lithotripsy (ESWL) and endourological procedures such as percutaneous nephrolithotomy (PCNL), ureterorenoscopy and retrograde intrarenal surgery (RIRS). The presence of anatomical anomalies, such as ectopic pelvic kidney, imposes limitations to such therapeutic procedures. This study is aimed to find a simple and effective way to treat the stones in ectopic kidney. Materials and Methods: From 2010 to 2014, nine patients underwent laparoscopic-assisted mini PCNL with Laser dusting for calculi in ectopic pelvic kidneys at our hospital. Retrograde pyelography was done to locate the kidney. Laparoscopy was performed and after mobilizing the bowel and peritoneum, the puncture was made in the kidney and using rigid mini nephroscope, and stones were dusted with Laser. Results: The median interquartile range (IQR) stone size was 18 (6.5) mm. Median (IQR) duration of the procedure was 90 (40) min. The median (IQR) duration of postoperative hospital stay was 4 (2) days. The stone clearance in our series was 88.9%, with only one patient having a residual stone. No intra- or post-operative complications were encountered. Conclusion: Laparoscopy-assisted mini PCNL with Laser dusting offers advantages in ectopic pelvic kidneys in achieving good stone clearance, especially in patients with a large stone burden or failed ESWL or RIRS. PMID:26834410
Current Evidence of Minimally Invasive Spine Surgery in the Treatment of Lumbar Disc Herniations.
Quirno, Martin; Vira, Shaleen; Errico, Thomas J
With the advent of new instrumentation and better imaging techniques that allowed less tissue trauma compared with traditional open procedures, while providing adequate or enhanced visualization of the pathologic site and based upon the successful experience of outpatient spine surgery to assist early ambulation, the trend and evolution toward ''minimal access'' or minimally invasive spine surgery began to develop with greater intensity. Many surgical techniques have flourished with the promise of delivering a safe and efficient alternative, including chemonucleolysis, manual percutaneous discectomy (MPD), automated percutaneous lumbar discectomy (APLD), and percutaneous lumbar laser discectomy (PLLD). Unfortunately, most of these techniques have been demonstrated to be inefficient with high complication rates. Only modifications of the original open discectomy in which direct visualization of the disc is obtained through either microscopic or endoscopic techniques have proven to be successful. This review outlines the historical journey that has inspired the development of these techniques and delineates the progressive clinical experience gained from their advent. PMID:26977554
Longitudinal Comparison of Enzyme- and Laser-Treated Intervertebral Disc by MRI, X-Ray, and Histological Analyses Reveals Discrepancies in the Progression of Disc Degeneration: A Rabbit Study.
Fusellier, Marion; Colombier, Pauline; Lesoeur, Julie; Youl, Samy; Madec, Stéphane; Gauthier, Olivier; Hamel, Olivier; Guicheux, Jérôme; Clouet, Johann
Regenerative medicine is considered an attractive prospect for the treatment of intervertebral disc (IVD) degeneration. To assess the efficacy of the regenerative approach, animal models of IVD degeneration are needed. Among these animal models, chemonucleolysis based on the enzymatic degradation of the Nucleus Pulposus (NP) is often used, but this technique remains far from the natural physiopathological process of IVD degeneration. Recently, we developed an innovative animal model of IVD degeneration based on the use of a laser beam. In the present study, this laser model was compared with the chemonucleolysis model in a longitudinal study in rabbits. The effects of the treatments were studied by MRI (T2-weighted signal intensity (T2wsi)), radiography (IVD height index), and histology (NP area and Boos' scoring). The results showed that both treatments induced a degeneration of the IVD with a decrease in IVD height and T2wsi as well as NP area and an increase in Boos' scoring. The enzyme treatment leads to a rapid and acute process of IVD degeneration. Conversely, laser radiation induced more progressive and less pronounced degeneration. It can be concluded that laser treatment provides an instrumental in vivo model of slowly evolving IVD degenerative disease that can be of preclinical relevance for assessing new prophylactic biological treatments of disc degeneration. PMID:27247937
Longitudinal Comparison of Enzyme- and Laser-Treated Intervertebral Disc by MRI, X-Ray, and Histological Analyses Reveals Discrepancies in the Progression of Disc Degeneration: A Rabbit Study
Colombier, Pauline; Lesoeur, Julie; Youl, Samy; Madec, Stéphane; Gauthier, Olivier; Hamel, Olivier; Guicheux, Jérôme; Clouet, Johann
Regenerative medicine is considered an attractive prospect for the treatment of intervertebral disc (IVD) degeneration. To assess the efficacy of the regenerative approach, animal models of IVD degeneration are needed. Among these animal models, chemonucleolysis based on the enzymatic degradation of the Nucleus Pulposus (NP) is often used, but this technique remains far from the natural physiopathological process of IVD degeneration. Recently, we developed an innovative animal model of IVD degeneration based on the use of a laser beam. In the present study, this laser model was compared with the chemonucleolysis model in a longitudinal study in rabbits. The effects of the treatments were studied by MRI (T2-weighted signal intensity (T2wsi)), radiography (IVD height index), and histology (NP area and Boos' scoring). The results showed that both treatments induced a degeneration of the IVD with a decrease in IVD height and T2wsi as well as NP area and an increase in Boos' scoring. The enzyme treatment leads to a rapid and acute process of IVD degeneration. Conversely, laser radiation induced more progressive and less pronounced degeneration. It can be concluded that laser treatment provides an instrumental in vivo model of slowly evolving IVD degenerative disease that can be of preclinical relevance for assessing new prophylactic biological treatments of disc degeneration. PMID:27247937
Primary success and one-year followup of percutaneous peripheral excimer laser angioplasty
NASA Astrophysics Data System (ADS)
Visona, Adriana; Liessi, Guido; Miserocchi, Luigi; Bonanome, Andrea; Lusiani, Luigi; Breggion, Giovanni; Pagnan, Antonio
Excimer laser angioplasty was performed in 59 patients (44 males and 17 females, mean age 63 +/- 9 years, range 39 - 77) affected by peripheral vascular disease. Fifty patients had a total occlusion of the superficial femoral artery, three of the iliac artery, and one of the popliteal artery; seven patients showed a subocclusive stenosis of the superficial femoral artery. A commercial excimer laser (Technolas Max-10) was used at the Xenon-Chloride wavelength of 308 nm. The laser operated at 120 ns pulse length and at 20 Hz repetition rate. Applied energy fluence was 20 mJ/pulse. The energy was delivered through a multifiber catheter, which combines 12 (7F) or 18 (9F) fibers (260 micron diameter each), concentrically arranged. Balloon dilatation was associated in 51 patients. Successful recanalization was obtained in 59 out of 61 patients (97%). Failure to recanalize the occluded arteries occurred in two cases, and was due to dissection. Early thrombosis and reocclusion (within 48 hours) was observed in five patients. The cumulative patency rate was 56% at one year. On the basis of these results, excimer laser assisted angioplasty seems a feasible and safe procedure. However, this technique did not solve the restenosis problem. A wide application of excimer laser as a stand alone approach can be foreseen for treatment of peripheral vascular disease.
The Effect and Feasibility Study of Transforaminal Percutaneous Endoscopic Lumbar Discectomy Via Superior Border of Inferior Pedicle Approach for Down-Migrated Intracanal Disc Herniations.
Ying, Jinwei; Huang, Kelun; Zhu, Minyu; Zhou, Beibei; Wang, Yu; Chen, Bi; Teng, Honglin
Transforaminal percutaneous endoscopic lumbar discectomy (PELD) is gradually regarded as an effective alternative to posterior open surgery. However, migrated herniations bring a great technical challenge even for experienced surgeons due to the absence of the appropriate approaching guideline. We aimed to describe a safe and effective approaching technique for the removal of down-migrations on the basis of the clinical outcomes and complications compared with the conventional approaching method.A total of 45 patients recommended to single-level PELD with foraminoplasty were randomly divided into 2 groups, group A received foraminoplasty via upper border of inferior pedicle, group B was approached through the common transforaminal route. The clinical outcomes were evaluated by Visual Analog Scale (VAS) for leg pain and Oswestry Disability Index (ODI) scores. Then participants were classified into 2 types of migrations (high-grade and low-grade) based on the extent of migration presented on preoperative magnetic resonance imaging (MRI). The various comparisons between the 2 surgical techniques were analyzed.The postoperative VAS and ODI scores significantly decreased in both of the 2 groups after surgery (P < 0.001). The follow-up continued 1 year. With increasing length of follow-up, the disparities in clinical outcomes between the 2 groups were gradually narrowing and there was no significant difference at the end of follow-up (P = 0.32; P = 0.46). There were no differences in the operation time and duration of hospital stay (P = 0.36; P = 0.08). The highly migration group in group B showed a significant longer operation time (P = 0.02), but the extent of migration did not have a significant influence on the operation time in group A with the modified approach (P = 0.19). There were no apparent approach-related complications in group A during the procedure and follow-up period.Foraminoplastic-PELD via upper border of inferior pedicle
The Effect and Feasibility Study of Transforaminal Percutaneous Endoscopic Lumbar Discectomy Via Superior Border of Inferior Pedicle Approach for Down-Migrated Intracanal Disc Herniations
Ying, Jinwei; Huang, Kelun; Zhu, Minyu; Zhou, Beibei; Wang, Yu; Chen, Bi; Teng, Honglin
Abstract Transforaminal percutaneous endoscopic lumbar discectomy (PELD) is gradually regarded as an effective alternative to posterior open surgery. However, migrated herniations bring a great technical challenge even for experienced surgeons due to the absence of the appropriate approaching guideline. We aimed to describe a safe and effective approaching technique for the removal of down-migrations on the basis of the clinical outcomes and complications compared with the conventional approaching method. A total of 45 patients recommended to single-level PELD with foraminoplasty were randomly divided into 2 groups, group A received foraminoplasty via upper border of inferior pedicle, group B was approached through the common transforaminal route. The clinical outcomes were evaluated by Visual Analog Scale (VAS) for leg pain and Oswestry Disability Index (ODI) scores. Then participants were classified into 2 types of migrations (high-grade and low-grade) based on the extent of migration presented on preoperative magnetic resonance imaging (MRI). The various comparisons between the 2 surgical techniques were analyzed. The postoperative VAS and ODI scores significantly decreased in both of the 2 groups after surgery (P < 0.001). The follow-up continued 1 year. With increasing length of follow-up, the disparities in clinical outcomes between the 2 groups were gradually narrowing and there was no significant difference at the end of follow-up (P = 0.32; P = 0.46). There were no differences in the operation time and duration of hospital stay (P = 0.36; P = 0.08). The highly migration group in group B showed a significant longer operation time (P = 0.02), but the extent of migration did not have a significant influence on the operation time in group A with the modified approach (P = 0.19). There were no apparent approach-related complications in group A during the procedure and follow-up period. Foraminoplastic-PELD via upper border of
Proliferative sickle retinopathy and neovascularization of the disc: regression following treatment with peripheral retinal scatter laser photocoagulation.
Kimmel, A S; Magargal, L E; Tasman, W S
Proliferative sickle retinopathy (PSR) is usually described as a peripheral neovascular tuft in a "sea fan" like configuration. While neovascularization of the disc (NVD) is a common finding in proliferative diabetic retinopathy (PDR), to our knowledge only one other case has been reported of NVD in an S-C patient in the absence of other contributing conditions. PSR has been shown to regress after treating hypoxic peripheral retina with peripheral circumferential retinal scatter photocoagulation (PCRSP). The following is a case report of an S-C patient with PSR and NVD/NVR which was originally treated elsewhere with scatter argon laser photocoagulation from the vascular arcades to just behind the equator. The peripheral "sea fan" and NVD did not regress. PCRSP to the zone of peripheral ischemia was then performed, and regression of the NVD and peripheral "sea fan" was achieved. This case illustrates the importance of concentrating laser treatment to the zones of retinal ischemia to achieve regression of associated neovascularization. PMID:2419814
Technique of percutaneous laser-assisted valve dilatation for valvar atresia in congenital heart disease.
Rosenthal, E; Qureshi, S A; Kakadekar, A P; Anjos, R; Baker, E J; Tynan, M
OBJECTIVE--To investigate the efficacy and safety of transcatheter laser-assisted valve dilatation for atretic valves in children with congenital heart disease. DESIGN--Prospective clinical study. SETTING--Supraregional paediatric cardiology centre. SUBJECTS--Eleven children (aged 1 day-11 years; weight 2.1-35.7 kg) with atresia of pulmonary (10) or tricuspid (one) valve underwent attempted laser-assisted valve dilatation as part of the staged treatment of their cyanotic heart disease. INTERVENTION--After delineating the atretic valve by angiography and/or echocardiography a 0.018 inch "hot tip" laser wire was used to perforate the atretic valve. Subsequently the valve was dilated with conventional balloon dilatation catheters up to the valve annulus diameter. RESULTS--Laser-assisted valve dilatation was successfully accomplished in nine children. In two neonates with pulmonary valve atresia, intact ventricular septum, and coexistent infundibular atresia the procedure resulted in cardiac tamponade: one died immediately and one later at surgery. During a follow up of 1-17 months (mean 11) two infants with pulmonary valve atresia and intact ventricular septum died (one with congestive cardiac failure). The remainder are either well palliated and do not require further procedures (three), or are awaiting further transcatheter or surgical procedures because of associated defects (four). CONCLUSIONS--Laser-assisted valve dilatation is a promising adjunct to surgery in this high risk group of patients. It may avoid surgery in some patients, and may reduce the number of surgical procedures in those requiring staged operations. Images PMID:8343325
Percutaneous peripheral excimer laser angioplasty: immediate success rate and short-term outcome
NASA Astrophysics Data System (ADS)
Visona, Adriana; Liessi, Guido; Bonanome, Andrea; Lusiani, Luigi; Miserocchi, Luigi; Pagnan, Antonio
Excimer Laser Angioplasty was attempted in 47 patients (36 males, 11 females, mean age 62+/- 7 years, range 39-77 years), affected by peripheral vascular disease. Thirty-seven patients had a total occlusion of the superficial femoral artery, 3 of the iliac artery and 1 of the popliteal artery; 6 patients showed a subocclusive stenosis of the superficial femoral artery. Occlusions and subocclusive stenoses were classified by length: < 10 cm (28 cases), > 10 cm (19 cases). A commercial excimer laser (Technolas Max-10) was used at the Xenon- Chloride wavelength of 308 nm. The laser operated at 60 ns pulse length and at 20-40 Hz repetition rate. Applied energy fluence was 20 mJ/pulse. The energy was delivered through a multifiber catheter, which combines 12 (7F) or 18 (9F) fibers (260 micron diameter each), concentrically arranged. Balloon dilatation was associated to complete the procedure in 38 cases. The treated arteries were successfully recanalized in 41 out of 47 patients (87%). Hemodynamic improvement was confirmed by a significant increase of ankle/brachial systolic pressure index (from 0.60+/- 0.17 to 0.79+/- 0.20, p < 0.005). Failure to recanalize arterial occlusion occurred in 6 cases, and was due to dissection in 3 patients and inability to cross the final segment of a long occlusion in 3 patients. The success rate was higher for lesions < 10 cm in length. Early reocclusion was observed in 7 patients and was associated with poor run-off. The cumulative patency rate at 1 month was 90.7%. Preliminary results are encouraging. More suitable catheters and better selection of patients should improve the efficacy of laser angioplasty and should allow to perform laser procedures without combining balloon angioplasty.
Utilization of a digital-versatile-disc pickup head for benchtop laser microfabrication.
Hautefeuille, Mathieu; Jimenez-Zenteno, Alejandro K; Pérez-Alcázar, Pablo Roberto; Hess-Frieling, Kristopher M; Fernandez-Sanchez, Gerardo; Velazquez, Victor; Grether-Gonzalez, Marcela; Lopez-Moreno, Enrique
Laser microfabrication is now offering interesting solutions to rapidly produce high-resolution photomasks or microstructures. However, most works require expensive commercial lasers and computer numerical control platforms, limiting its use by a large public. In this paper, we report the construction of a simple, custom-made, easily reproducible, automated laser system, based on a DVD optical pickup head. A user-friendly computer interface specifically designed to operate a motorized three-axis platform with micrometric precision controls focus distance and in-plane displacements. Writing performance characterization for both direct ablation and sintering of commercial black toner demonstrated flexibility in tridimensional microfabrication resolution and speed thanks to precise management of laser power and exposure time, with a minimal resolution of 3.1 μm. PMID:22410998
Ablation of intervertebral discs in dogs using a MicroJet-assisted dye-enhanced injection device coupled with the diode laser
NASA Astrophysics Data System (ADS)
Bartels, Kenneth E.; Henry, George A.; Dickey, D. Thomas; Stair, Ernest L.; Powell, Ronald; Schafer, Steven A.; Nordquist, Robert E.; Frederickson, Christopher J.; Hayes, Donald J.; Wallace, David B.
Use of holmium laser energy for vaporization/coagulation of the nucleus pulposus in canine intervertebral discs has been previously reported and is currently being applied clinically in veterinary medicine. The procedure was originally developed in the canine model and intended for potential human use. Since the pulsed (15 Hz) holmium laser energy exerts photomechanical and photothermal effects, the potential for extrusion of additional disc material to the detriment of the patient is possible using the procedure developed for the dog. To reduce this potential complication, use of diode laser (805 nm - CW mode) energy, coupled with indocyanine green (ICG) as a selective laser energy absorber, was formulated as a possible alternative. Delivery of the ICG and diode laser energy was through a MicroJet device that could dispense dye interactively between individual laser 'shots.' Results have shown that it is possible to selectively ablate nucleus pulposus in the canine model using the device described. Acute observations (gross and histopathologic) illustrate that accurate placement of the spinal needle before introduction of the MicroJet device is critically dependent on the expertise of the interventional radiologist. In addition, the success of the overall technique depends on consistent delivery of both ICG and diode laser energy. Minimizing tissue carbonization on the tip of the MicroJet device is also of crucial importance for effective application of the technique in clinical veterinary medicine.
Percutaneous Ultrasound-Guided Laser Ablation with Contrast-Enhanced Ultrasonography for Hyperfunctioning Parathyroid Adenoma: A Preliminary Case Series
Jiang, Tianan; Chen, Fen; Zhou, Xiang; Hu, Ying; Zhao, Qiyu
The study was to evaluate the safety and effectiveness of ultrasound-guided percutaneous laser ablation (pLA) as a nonsurgical treatment for primary parathyroid adenoma. Surgery was contraindicated in, or refused by, the included patients. No lesion enhancement on contrast-enhanced ultrasound immediately after pLA was considered "complete ablation." Nodule size, serum calcium, and parathyroid hormone level were compared before and after pLA. Complete ablation was achieved in all 21 patients with 1 (n = 20) or 2 (n = 1) sessions. Nodule volume decreased from 0.93 ± 0.58 mL at baseline to 0.53 ± 0.38 and 0.48 ± 0.34 mL at 6 and 12 months after pLA (P < 0.05). At 1 day, 6 months, and 12 months after pLA, serum PTH decreased from 15.23 ± 3.00 pmol/L at baseline to 7.41 ± 2.79, 6.95 ± 1.78, and 6.90 ± 1.46 pmol/L, serum calcium decreased from 3.77 ± 0.77 mmol/L at baseline to 2.50 ± 0.72, 2.41 ± 0.37, and 2.28 ± 0.26 mmol/L, respectively (P < 0.05). At 12 months, treatment success (normalization of PTH and serum calcium) was achieved in 81%. No serious complications were observed. Ultrasound-guided pLA with contrast-enhanced ultrasound is a viable alternative to surgery for primary parathyroid adenoma. PMID:26788059
Percutaneous Ultrasound-Guided Laser Ablation with Contrast-Enhanced Ultrasonography for Hyperfunctioning Parathyroid Adenoma: A Preliminary Case Series.
Jiang, Tianan; Chen, Fen; Zhou, Xiang; Hu, Ying; Zhao, Qiyu
The study was to evaluate the safety and effectiveness of ultrasound-guided percutaneous laser ablation (pLA) as a nonsurgical treatment for primary parathyroid adenoma. Surgery was contraindicated in, or refused by, the included patients. No lesion enhancement on contrast-enhanced ultrasound immediately after pLA was considered "complete ablation." Nodule size, serum calcium, and parathyroid hormone level were compared before and after pLA. Complete ablation was achieved in all 21 patients with 1 (n = 20) or 2 (n = 1) sessions. Nodule volume decreased from 0.93 ± 0.58 mL at baseline to 0.53 ± 0.38 and 0.48 ± 0.34 mL at 6 and 12 months after pLA (P < 0.05). At 1 day, 6 months, and 12 months after pLA, serum PTH decreased from 15.23 ± 3.00 pmol/L at baseline to 7.41 ± 2.79, 6.95 ± 1.78, and 6.90 ± 1.46 pmol/L, serum calcium decreased from 3.77 ± 0.77 mmol/L at baseline to 2.50 ± 0.72, 2.41 ± 0.37, and 2.28 ± 0.26 mmol/L, respectively (P < 0.05). At 12 months, treatment success (normalization of PTH and serum calcium) was achieved in 81%. No serious complications were observed. Ultrasound-guided pLA with contrast-enhanced ultrasound is a viable alternative to surgery for primary parathyroid adenoma. PMID:26788059
Immediate and midterm follow-up results of excimer laser application in complex percutaneous coronary interventions: Report from a single center experience
Tarsia, Giandomenico; Viceconte, Nicola; Takagi, Kensuke; Biscione, Carmine; Del Prete, Giuseppe; Polosa, Domenico; Osanna, Roccoaldo; Lisanti, Pasquale
Objective To assess the efficacy and safety of laser-assisted percutaneous coronary interventions (PCI) in an unselected population. Methods One hundred consecutive patients, who underwent a laser assisted PCI between January 2008 and March 2012, were included in the present study. Fifty-one patients underwent laser ablation for thrombus vaporization (Group 1), 36 patients for neointima/plaque debulking (Group 2) and 13 patients for lesion compliance modification in calcified lesions (Group 3). Results The rate of in-hospital serious events was 2%. The cumulative laser success was 82%, and it was significantly higher for Group 1 and Group 2 in comparison with Group 3 (p = 0.001). Furthermore, the need for repeat revascularization was significantly higher in the Group 3 compared with the others two groups (46% vs. 8% for Group 1 and 11% for Group 2, p = 0.03). The MACE rate was 14%. There was a trend toward a higher MACE rate in the Group 3 compared with others two groups (p = 0.05). Conclusions Laser ablation is an effective and safe tool for complex PCI. Patients underwent laser for thrombus vaporization or for neointima/plaque debulking had better immediate success and better outcome at follow-up than patients underwent laser for lesion compliance modification. PMID:24265882
Vialle, Luis Roberto; Vialle, Emiliano Neves; Suárez Henao, Juan Esteban; Giraldo, Gustavo
Lumbar disc herniation is the most common diagnosis among the degenerative abnormalities of the lumbar spine (affecting 2 to 3% of the population), and is the principal cause of spinal surgery among the adult population. The typical clinical picture includes initial lumbalgia, followed by progressive sciatica. The natural history of disc herniation is one of rapid resolution of the symptoms (four to six weeks). The initial treatment should be conservative, managed through medication and physiotherapy, sometimes associated with percutaneous nerve root block. Surgical treatment is indicated if pain control is unsuccessful, if there is a motor deficit greater than grade 3, if there is radicular pain associated with foraminal stenosis, or if cauda equina syndrome is present. The latter represents a medical emergency. A refined surgical technique, with removal of the extruded fragment and preservation of the ligamentum flavum, resolves the sciatic symptoms and reduces the risk of recurrence over the long term. PMID:27019834
Percutaneous coronary excimer laser angioplasty in patients with stable and unstable angina pectoris. Acute results and incidence of restenosis during 6-month follow-up.
Karsch, K R; Haase, K K; Voelker, W; Baumbach, A; Mauser, M; Seipel, L
A clinical study was conducted to evaluate the efficacy and safety of percutaneous coronary excimer laser angioplasty in 60 patients with coronary artery disease. Forty-nine patients had stable exertional angina, and 11 patients had unstable angina despite medical therapy. A novel 1.4-mm diameter catheter with 20 quartz fibers of 100-microns diameter each arranged concentrically around a central lumen suitable for a 0.014-in. flexible guide wire was coupled to an excimer laser. A commercial excimer laser emitting energy at a wavelength of 308 nm with a pulse duration of 60 nsec was used. The laser was operated at 20 Hz. Mean energy transmission was 30 +/- 5 mJ/mm2. In five of the 60 patients, laser angioplasty was not attempted. In 23 patients with laser ablation alone, percent stenosis decreased from 76 +/- 14% before to 27 +/- 17% after ablation and was 34 +/- 15% at the early follow-up angiogram. In 32 patients, additional balloon angioplasty was performed because of vessel closure after laser ablation in 11 and an insufficient qualitative result in 21 patients. Of the 11 patients with unstable angina, one patient died due to vessel closure 3 hours after intervention, and two patients developed a myocardial infarction. In 22 of 47 patients with late follow-up angiography, restenosis within the 6-month follow-up period occurred. Rate of restenosis was higher in patients treated with laser ablation and balloon angioplasty (16 of 28) than in patients treated with laser ablation alone (six of 19). These results suggest that coronary excimer laser angioplasty for ablation of obstructive lesions is feasible and safe in patients with stable angina. However, development of new catheter systems is necessary for an improved success rate. PMID:2344680
Principles of lasers and biophotonic effects.
Knappe, Verena; Frank, Frank; Rohde, Ewa
In this review, we discuss how, due to a variety of different interactions between laser radiation and biological tissue, the laser has become an established instrument in most medical fields. Depending on the interaction time and the effective power density, three types of laser tissue interaction can be distinguished: photochemical effects, photothermal effects, and photomechanical and photoionizing effects. After a description of the physical mechanisms, the typical parameters, and the medical applications of these effects, a review of the laser types used in medicine is given. For percutaneous laser disc decompression (PLDD), lasers in the near-infrared region (Nd:YAG, Ho:YAG, and diode lasers) and with visible green radiation (frequency doubled Nd:YAG, called "KTP laser") were reported to be effective. PMID:15671714
Excimer ablation of human intervertebral disc at 308 nanometers.
Wolgin, M; Finkenberg, J; Papaioannou, T; Segil, C; Soma, C; Grundfest, W
Excimer laser energy, which has been shown to photoablate tissue at a precisely controllable rate with minimal thermal damage, was applied to human intervertebral disc in an effort to develop a technique for percutaneous discectomy. Cadaveric samples of human disc were used. Excimer laser energy was produced by a XeCl, magnetically switched, long-pulse laser working at 308 nm, 20 Hz. Annulus tissue of approximately 1 mm thickness was placed in contact with the output tip of a 400 microns core diameter quartz fiber, and measurements of ablation rate were made at different radiant exposures. Ablation rates were found to vary linearly with radiant exposure, from 0.7 micron/pulse at 10 mJ/mm2 to 11.0 microns/pulse at 55 mJ/mm2, with a correlation coefficient of 0.984. Threshold radiant exposure, calculated by extrapolation, was found to be about 7 mJ/mm2. Histologic analysis showed a minimum of thermal damage in these specimens, and when ablated with modification to maintain constant fiber-tissue contact, thermal injury was nearly absent, as compared to samples ablated with Nd:YAG through a contact probe. Thermographic analysis, performed using the AGA 782 Digital Thermography system, showed increasing temperature with increasing radiant exposure, with a maximum temperature of 47.2 degrees C at 55 mJ/mm2. In that precise tissue ablation was demonstrated with minimal generated heat, and excimer energy at 308 nm is transmissible through fiber optics, excimer holds great promise for the development of a percutaneous discectomy technique. PMID:2716456
Feasibility of minimally-invasive fiber-based evaluation of chondrodystrophoid canine intervertebral discs by light absorption and scattering spectroscopy
NASA Astrophysics Data System (ADS)
Jiang, Yuanyuan; McKeirnan, Kelci; Piao, Daqing; Bartels, Kenneth E.
proximity to the fiber-tip. Preliminary measurements on cadaveric canine intervertebral discs indicated significant reduction of scattering constituents and possible diminishment of water content after percutaneous laser disc ablation (PLDA). This fiber-needle based sensing configuration may be feasible for integrating the evaluation of calcification and water content into the work-flow of holmium:YAG laser disc ablation for pre-operative in-line detection and post-operative evaluation of therapeutic interventions regarding the chondrodystrophic disc.
Holmium Laser Enucleation of the Prostate With Percutaneous Nephrostomy Into the Transplanted Kidney in Patient With Severe Benign Prostatic Hyperplasia With Vesicoureteral Reflux - A Case Report.
Nohara, Takahiro; Matsuyama, Satoko; Shima, Takashi; Kawaguchi, Shohei; Seto, Chikashi
A 66-year-old male, who had received renal transplantation 10 years before, was admitted to our hospital with urinary retention. The prostate volume was 169.2 ml. Furthermore, grade 5 vesicoureteral reflux (VUR) was shown in the cystography. Holmium laser enucleation of prostate (HoLEP) was performed, and percutaneous nephrostomy to the transplanted kidney was performed simultaneously to prevent from severe perioperative infection. After that, renal graft function improved and no urinary retention reoccurred, although surgical repair against VUR was necessary 10 months after HoLEP. We conclude that surgical treatment for BPH after kidney transplantation should be strongly considered with care for infections. PMID:26793574
Holmium Laser Enucleation of the Prostate With Percutaneous Nephrostomy Into the Transplanted Kidney in Patient With Severe Benign Prostatic Hyperplasia With Vesicoureteral Reflux – A Case Report
Nohara, Takahiro; Matsuyama, Satoko; Shima, Takashi; Kawaguchi, Shohei; Seto, Chikashi
A 66-year-old male, who had received renal transplantation 10 years before, was admitted to our hospital with urinary retention. The prostate volume was 169.2 ml. Furthermore, grade 5 vesicoureteral reflux (VUR) was shown in the cystography. Holmium laser enucleation of prostate (HoLEP) was performed, and percutaneous nephrostomy to the transplanted kidney was performed simultaneously to prevent from severe perioperative infection. After that, renal graft function improved and no urinary retention reoccurred, although surgical repair against VUR was necessary 10 months after HoLEP. We conclude that surgical treatment for BPH after kidney transplantation should be strongly considered with care for infections. PMID:26793574
ERIC Educational Resources Information Center
Carty, Brad
Describes features of laserdisc and discusses its advantages over videotape and audiotape in the areas of image and sound quality, random access, and permanence. Current and future applications of laserdisc technology in art and music are highlighted. (MAB)
Multipotent Mesenchymal Stem Cell Treatment for Discogenic Low Back Pain and Disc Degeneration
Zeckser, Jeffrey; Wolff, Michael; Tucker, Jason; Goodwin, Josh
Low back pain with resultant loss of function, decreased productivity, and high economic costs is burdensome for both the individual and the society. Evidence suggests that intervertebral disc pathology is a major contributor to spine-related pain and degeneration. When commonly used conservative therapies fail, traditional percutaneous or surgical options may be beneficial for pain relief but are suboptimal because of their inability to alter disc microenvironment catabolism, restore disc tissue, and/or preserve native spine biomechanics. Percutaneously injected Multipotent Mesenchymal Stem Cell (MSC) therapy has recently gained clinical interest for its potential to revolutionarily treat disc-generated (discogenic) pain and associated disc degeneration. Unlike previous therapies to date, MSCs may uniquely offer the ability to improve discogenic pain and provide more sustained improvement by reducing disc microenvironment catabolism and regenerating disc tissue. Consistent treatment success has the potential to create a paradigm shift with regards to the treatment of discogenic pain and disc degeneration. PMID:26880958
Interactive Optical Disc Systems: Part 1: Analog Storage.
ERIC Educational Resources Information Center
Hessler, David W.
Details distinction between digital and analog data, advantages of analog storage, and optical disc use to store analog data. Configuration and potential of three levels of laser disc systems are explained. Selection of display devices for use with laser disc systems and accessing audio data are addressed. (Continued in next issue.) (EJS)
In Praise of Mr. S. Platter and His Marvelous, Magnificent CD ROM Laser Disc Index for ERIC and PSYCHLIT.
ERIC Educational Resources Information Center
Huffman, Robert F.
These instructions are designed to help patrons of the University of Missouri-Columbia library perform searches on PSYCHLIT, a CD-ROM (compact disc, read only memory) version of the Psych Abstracts database, and a CD-ROM version of the ERIC database, both produced by SilverPlatter Information Services. Basic information is provided about the disk…
NASA Technical Reports Server (NTRS)
Picha, G. J.; Taylor, S. R.
A surface possessing a regular array of micro-pillars was evaluated with regard to its ability to control epithelial downgrowth at the percutaneous interface. A range of pillar sizes were applied to the vertical segment of T shaped Biomer (R) implants. These percutaneous tabs were implanted into the dorsum of cats for a period of 6 weeks using a standardized surgical technique. Comments were made post-operatively and at the time of retrieval. A quantitative scoring system was applied to these observations as well as histological results. As observed, the pillar morphology used displayed the ability to control epithelial downgrowth. Collagen ingrowth into the interpillar spaces and possibly direct interactions of the epithelial cells with the morphology may account for the inhibition. The reproducibility of epithelial inhibition is, however, limited by other factors which are currently not well understood. These factors and potential methods of assessment are discussed.
Ho:YAG laser: intervertebral disk cell interaction using three-dimensional cell culture system
NASA Astrophysics Data System (ADS)
Sato, Masato; Ishihara, Miya; Arai, Tsunenori; Asazuma, Takashi; Kikuchi, Toshiyuki; Kikuchi, Makoto; Fujikawa, Kyosuke
The purpose of this study is to evaluate the influence on the intervertebral disc cells after laser irradiation using three- dimensional culture system and to clarify the optimum Ho:YAG laser irradiation condition on percutaneous laser disc decompression (PLDD) for lumbar disc herniation. Since the Ho:YAG laser ablation is characterized by water-vapor bubble dynamics, not only thermal effect but also acoustic effect on cell metabolism might occur in the intervertebral disc. We studied the disc cell reaction from the metabolic point of view to investigate photothermal and photoacoustic effects on three-dimensional cultured disc cell. Intervertebral discs were obtained from female 30 Japanese white rabbits weighing about 1 kg. A pulsed Ho:YAG laser (wavelength: 2.1 micrometer, pulse width: about 200 microseconds) was delivered through a 200 micrometer-core diameter single silica glass fiber. We used the Ho:YAG laser irradiation fluence ranging from 60 to approximately 800 J/cm2 at the fiber end. To investigate acoustic effect, the acoustic transducer constructed with polyvinylidene fluoride (PVdF) film and acoustic absorber was used to detect the stress wave. Thermocouple and thermography were used to investigate thermal effect. Concerning damage of plasma membrane and ability of matrix synthesis, thermal effect might mainly affect cell reaction in total energy of 54 J (closed to practically used condition), but in 27 J, acoustic effect might contribute to it. We found that total energy was key parameter among the optimum condition, so that temperature and/or stress wave may influence Ho:YAG laser-disc cell interactions.
Vitrectomy, argon laser, and gas tamponade for serous retinal detachment associated with an optic disc pit: a case report.
Snead, M P; James, N; Jacobs, P M
We report the case of a 9-year-old boy with a right optic disc pit and associated serous retinal detachment of the macula. This was treated by vitrectomy, endolaser, and gas tamponade as a primary procedure, which resulted in complete resolution. We review the literature and conclude that further reports of the management of this uncommon condition are required so that firmer guidelines on treatment can be established. Images PMID:2043587
Optical laser technology, specifically CD-ROM (Compact Disc - Read Only Memory) and its application to the storage and retrieval of information
NASA Astrophysics Data System (ADS)
Lind, David J.
One of the significant problems of this information age is the production of vast amounts of information in a form that is neither convenient nor cost effective. A possible solution to this, is the new optical laser technology and its use in the storage and retrieval of large amounts of information. In many areas of DOD, the greatest benefit would be the regained space and weight associated with the distribution of the manuals and other typically paper products on a Compact Disc - Read Only Memory (CD-ROM). One CD-ROM weighs less than an ounce and is capable of storing over 270,000 pages of text. The saved shipping and handling costs alone would be astronomically reduced not to mention the end user who would have a more effective and efficient product. The CD-ROM is designed to work as a peripheral device to a microcomputer and can therefore be made available to any user within an IBM compatible microcomputer. The application/demonstration portion of this thesis took over 2 million database records, from the Transaction Ledger on Disc (TLOD), at the Naval Supply Center (NSC) in Oakland and pressed them to a single CD-ROM. The menu driven retrieval software with indexing on 3 criteria was also provided.
Laser beam scattering on an inhomogeneous ensemble of elliptical discs modelling red blood cells in an ectacytometer
Nikitin, Sergei Yu; Kormacheva, M A; Priezzhev, A V; Lugovtsov, Andrei E
We have theoretically studied the effect of difference in particle shapes on the appearance of the diffraction pattern, which arises in the scattering of a laser beam on a dilute suspension of erythrocytes in an ectacytometer. We have proposed data processing algorithms allowing one to estimate the red blood cell shape parameter variance under conditions of laser ectacytometry. The conclusions of the theoretical analysis are verified experimentally. (laser methods in biology)
Use of the holmium:YAG laser for percutaneous photothermal ablation of cervical invertebral disks in dogs
NASA Astrophysics Data System (ADS)
Rochat, Mark; Henry, George A.; Campbell, Gregory A.; Stair, Ernest L.; Bartels, Kenneth E.; Dickey, Tom
Holmium:YAG laser ablation of thoracolumbar disks in dogs has been shown to be an effective alternative to standard surgical fenestration techniques. Our hypothesis was the Holmium:YAG laser could be equally effective and safe when used to ablate cervical intervertebral disks. Six normal chondrodystrophoid breed dogs were used. A sterile, cleaved, 320 micrometers , low-OH quartz optical fiber was inserted into each needle and the laser activated for 40 s at 2 W mean power and a 15 Hz pulse repetition rate for a total of 80 J. Dogs were observed in pain, neurological deficits, or other complications for 24 weeks. At 24 weeks, dogs were euthanatized and cervical disks collected and placed in 10 percent neutral buffered formalin. Disks were decalcified, sectioned at 5 micrometers , and stained with H and E. No problems were encountered during the procedure except occasional difficulties passing the needle by the shoulder to enter the C6-7 disk space. No complications, including neurologic deficits or pain were observe during the 24 weeks. Histologic examination revealed varying degrees of necrosis and defects created in the nucleus pulposus by laser irradiation. In some instances there was evidence of mild adjacent annular and bony thermal injury. On the basis of these result, the Ho:YAG laser appears to be a safe and efficacious method for ablation of canine cervical disks.
Annulo-nucleoplasty using Disc-FX in the management of lumbar disc pathology: Early results
Kumar, Aravind; Siddharth M, Shah; Sambhav P, Shah; Tan, Justin
Background Back pain due to Lumbar Disc Disease is a major clinical problem. The treatment options range from physiotherapy to fusion surgery. A number of minimally invasive procedures have also been developed in the recent past for its management. Disc-FX is a new minimally invasive technique that combines percutaneous discectomy, nuclear ablation and annular modification. Literature on its role in the management of lumbar disc pathology is scarce. Methods We included 24 consecutive patients who underwent the Disc-FX for back pain due to lumbar disc pathology non-responsive to non-operative treatment for a period of at least 6 months. Based on Magnetic Resonance Imaging (MRI) these patients fell into 2 groups – those with degenerative disc disease (DDD) (n = 12) and those with a contained lumbar disc herniation (CLDH)(n = 12). They were evaluated using the Visual analogue scale (VAS), Oswestry Disability Index (ODI) and Short Form-36 (SF-36) scores preoperatively and postoperatively. Results The mean age was 37.9 years (21-53 years). There were 17 males and 7 females. One patient in each subgroup was excluded from the final evaluation. Significant improvement was seen in all outcome measures. The overall rate of reintervention for persistent symptoms was 18.18% (4/22); in the CLDH subgroup, it was 36.36% (4/11). Conclusions and level of evidence Early results after the Disc-FX procedure suggest that it s a reasonable treatment option for patients with back pain due to lumbar disc disease, especially for those with DDD who fail conservative treatment. It could be an alternative to procedures like fusion or disc replacement. This study presents Level IV evidence. Clinical relevance We feel that our study establishes Disc-FX as a modality of treating symptomatic lumbar disc disease due to DDD. However, longer term prospective studies are needed to prove this and to evaluate its role in the treatment of patients with CLDH. PMID:25694914
400W Nd:YAG composite ceramic thin-disc laser in 10ns pulse at 167kHz
NASA Astrophysics Data System (ADS)
Iyama, K.; Furukawa, H.; Chosrowjan, H.; Sakurai, T.; Tsubakimoto, K.; Yoshida, H.; Fujita, H.; Fujita, M.; Miyanaga, N.; Tamaoki, Y.; Kato, Y.; Kawashima, T.
Double-clade crystalline fiber waveguide (CFW) has been produced by using adhesive-free bond (AFB®) technology. The waveguide consists of a 1 at.% Yb:YAG core, un-doped YAG inner cladding and ceramic spinel outer cladding. It is a direct analog of the conventional double-clad glass fiber laser in the crystal domain. Signal gain of 45 or 16.5 dB has been measured in a preliminary master oscillator power amplifier (MOPA) experiment. Due to the high laser gain and the weak Fresnel reflection at the uncoated waveguide ends, the CFW even starts self-lasing above a certain pump power. Laser output power of 4 W in the backward propagation direction has been measured for input pump power of 44 W. After considering the same amount of forward propagated laser power, the laser efficiency to the absorbed pump power is estimated to be about 44%. In principle, CFW can have extremely large single mode area for high efficiency and high power laser applications. So far, Single mode area < 6700 μm2 has been demonstrated in Er:YAG CFWs.
Walther, Andreas; André, Xavier; Drechsler, Markus; Abetz, Volker; Müller, Axel H E
We describe the synthesis and the solution properties of sheet- and disclike Janus particles, containing an inner crosslinked polybutadiene (PB) layer and two different outer sides of polystyrene (PS) and poly(tert-butyl methacrylate) (PtBMA). The structures formed upon adsorption of the flat Janus particles onto solid substrates as well as in THF solution are investigated. The Janus discs are obtained in a template-assisted synthetic pathway followed by sonication. Selectively crosslinking the lamellar PB domains in a well-ordered lamellar microphase-separated bulk morphology of PS-block-PB-block-PtBMA (SBT) block terpolymers leads to the conservation of the compartmentalization of the two outer blocks. Sonication of the crosslinked block terpolymer templates renders soluble sheet- and disclike Janus particles, the size of which can be tuned from the micrometer range down to the nanometer scale. Small-angle X-ray scattering, transmission electron microscopy, dynamic light scattering, scanning force microscopy, and scanning electron microscopy are used to characterize the template-assisted synthetic process and the solution properties. Cryogenic transmission electron microscopy in THF and TEM of particles, embedded into a photo-crosslinkable silicon oil, indicate a supramolecular aggregation behavior of the Janus discs in concentrated solutions. Pendant drop tensiometry demonstrates that Janus sheets and discs can be used to stabilize liquid-liquid interfaces, rendering these materials interesting for future applications. PMID:17441717
A comparative study to analyze the efficacy and safety of flexible ureteroscopy combined with holmium laser lithotripsy for residual calculi after percutaneous nephrolithotripsy
Xu, Gang; Wen, Jiaming; Li, Zhongyi; Zhang, Zhewei; Gong, Xiuqing; Chen, Jimin; Du, Chuanjun
A certain proportion of patients with initial Percutaneous nephrolithotripsy (PCNL) management require ancillary procedures to increase the stone-free rate. In this study, we aim to analyze the efficacy and safety of flexible ureteroscopy combined with holmium laser lithotripsy (F-UL) for treatment of residual calculi after PCNL by comparison with extracorporeal shockwave lithotripsy (SWL). Total of 96 patients with residual renal calculi (4 mm to 20 mm) after PCNL was enrolled from May 2010 to March 2013. They were randomly divided into two groups: US Group: patients were treated with F-UL; SWL Group: patients were treated with SWL. Follow-up was made one month and three months after treatment. The mean residual stone size after PCNL was 12.4 ± 4.3 mm in US group compared with 11.9 ± 4.5 in SWL group. The stone-free rate was 84.7% one month after surgical procedure in US group, this rate increased to 91.3% in the third months, while the stone-free rate in SWL group is 64.6% one month after treatment and 72.9% in the third month. For residual stone in lower calyx, the stone-free rate three month after treatment was 90.4% in US group compared to 65.2% in SWL group (P < 0.05). The overall complication rate was low in both groups, no severe complication was found. Both F-UL and SWL are safe and effective methods for residual calculi after PCNL, without severe complications. F-UL provided significantly higher stone-free rate compared with SWL, especially for low-pole calculi. PMID:26064375
New instrument for percutaneous posterolateral lumbar foraminoplasty: case series of 134 with instrument design, surgical technique and outcomes.
Li, Zhenzhou; Hou, Shuxun; Shang, Weilin; Song, Keran; Zhao, Hongliang
Current solutions for treating uncontained lumbar disk herniation include laser assisted endoscopic foraminoplasty and Transforaminal Endoscopic Spine System, both of which have some issues in clinical practice. This study aims to report the design of a new instrument for percutaneous posterolateral foraminoplasty. 148 patients with uncontained lumbar disk herniation were treated with percutaneous foraminoplasty followed by transforaminal endoscopic discectomy. Follow up were obtained for 134 cases. The VAS scores of pre-operative and post-operative low back pain and sciatica were compared. Oswestry Disability Index (ODI) and MacNab scores were also obtained. Follow-up was up to 5 years postoperatively. There were 75 of excellent, 49 of good and 5 of fair according to MacNab score system, with total successful rate up to 92.5%. 5 cases with L5S1 disc herniation complained about irritation to the dorsal root ganglion. In conclusion, the new transforaminal endoscopic discectomy instrument is safe and effective for percutaneous foraminoplasty. PMID:26628949
New instrument for percutaneous posterolateral lumbar foraminoplasty: case series of 134 with instrument design, surgical technique and outcomes
Li, Zhenzhou; Hou, Shuxun; Shang, Weilin; Song, Keran; Zhao, Hongliang
Current solutions for treating uncontained lumbar disk herniation include laser assisted endoscopic foraminoplasty and Transforaminal Endoscopic Spine System, both of which have some issues in clinical practice. This study aims to report the design of a new instrument for percutaneous posterolateral foraminoplasty. 148 patients with uncontained lumbar disk herniation were treated with percutaneous foraminoplasty followed by transforaminal endoscopic discectomy. Follow up were obtained for 134 cases. The VAS scores of pre-operative and post-operative low back pain and sciatica were compared. Oswestry Disability Index (ODI) and MacNab scores were also obtained. Follow-up was up to 5 years postoperatively. There were 75 of excellent, 49 of good and 5 of fair according to MacNab score system, with total successful rate up to 92.5%. 5 cases with L5S1 disc herniation complained about irritation to the dorsal root ganglion. In conclusion, the new transforaminal endoscopic discectomy instrument is safe and effective for percutaneous foraminoplasty. PMID:26628949
... treat this condition, alternatives to disc replacement include fusion, nonoperative care or no treatment. Typically, surgery is ... operative treatment for disc pain has been spinal fusion. This is a surgical procedure in which disc ...
NASA Technical Reports Server (NTRS)
Barack, W. N.; Domas, P. A.; Beekman, S. W. (Inventor)
A rotatable disc is described that consists of parallel plates tightly joined together for rotation about a hub. Each plate is provided with several angularly projecting spaced lands. The lands of each plate are interposed in alternating relationship between the lands of the next adjacent plate. In this manner, circumferential displacement of adjacent sectors in any one plate is prevented in the event that a crack develops. Each plate is redundantly sized so that, in event of structural failure of one plate, the remaining plates support a proportionate share of the load of the failed plate. The plates are prevented from separating laterally through the inclusion of generally radially extending splines which are inserted to interlock cooperating, circumferentially adjacent lands.
Immunolocalization of Delta-Giardin within the Ventral Disc in of Trophozoites and in cysts of Giardia duodenalis using the Multiplex Laser Scanning Confocal Microscopy
Technology Transfer Automated Retrieval System (TEKTRAN)
Immunolocalization of alpha2-, beta- and delta-giardin in Giardia showed that in the trophozoites and cysts delta-giardin it strictly associated with the ventral disc. Optical sectioning of the ventral discs, together with quantitative colocalization of the immunoreactivity for delta- and beta-giard...
Percutaneous techniques for cervical pain of discal origin.
Gangi, Afshin; Tsoumakidou, Georgia; Buy, Xavier; Cabral, Jose Facundo; Garnon, Julien
Cervical discogenic pain is an important cause of suffering and disability in the adult population. Pain management in cervical disc herniation relies initially on conservative care (rest, physiotherapy, and oral medications). Once conservative treatment has failed, different percutaneous minimally invasive radiological procedures can be applied to relief pain. This article offers a systematic review on the percutaneous minimally invasive techniques that can be advocated for the treatment of cervical pain of discal origin. Periradicular steroid injection under image guidance (computed tomography or magnetic resonance imaging) is the first technique to be considered. The steroid injection aims at reducing the periradicular inflammation and thus relieves the radicular pain. The steroid injections present satisfying short-term results, but pain can recur in the long term. Whenever the steroid injections fail to relieve pain from a contained cervical disc herniation, the more invasive percutaneous disc decompression techniques should be proposed. Percutaneous radiofrequency nucleoplasty is the most often applied technique on the cervical level with a low risk of thermal damage. When the indications and instructions are respected, radiofrequency nucleoplasty presents accepted safety and efficacy levels. PMID:21500138
Simpson, S T
This article describes the functional anatomy of intervertebral discs and their relationship to the vertebrae and spinal cord. The pathologic events and clinical complications of intervertebral disc disease are described. A discussion of proper staging of disc disease and appropriate conservative management of degenerative disc disease is included. PMID:1641922
Novel indication for posterior dynamic stabilization: Correction of disc tilt after lumbar total disc replacement
Cheng, Wayne K.; Palmer, Daniel Kyle; Jadhav, Vikram
Background The increase in total disc replacement procedures performed over the last 5 years has increased the occurrence of patients presenting with postoperative iatrogenic deformity requiring revision surgery. Proposed salvage treatments include device retrieval followed by anterior lumbar interbody fusion or posterior fusion. We propose a novel approach for the correction of disc tilt after total disc replacement using a posterior dynamic stabilization system. Methods Pedicle screws can be inserted either in an open manner or percutaneously by standard techniques under fluoroscopy. The collapsed side is expanded, and the convex side is compressed. Universal spacers are placed bilaterally, with the spacer on the collapsed side being taller by 6 mm. Cords are threaded through the spacers and pulled into place with the tensioning instrument. Extra tension is applied to the convex side, and the wound is closed by standard techniques. Results Three patients presenting with tilted total disc replacement devices underwent corrective surgery with posterior dynamic stabilization. Radiographs confirmed correction of deformity in all cases. Conclusions/Level of Evidence This technical note presents a novel indication for posterior dynamic stabilization and describes its surgical application to the correction of disc tilt after total disc replacement. This is level V evidence. PMID:25802667
Broken discs: warp propagation in accretion discs
NASA Astrophysics Data System (ADS)
Nixon, Christopher J.; King, Andrew R.
We simulate the viscous evolution of an accretion disc around a spinning black hole. In general, any such disc is misaligned, and warped by the Lense-Thirring effect. Unlike previous studies, we use effective viscosities constrained to be consistent with the internal fluid dynamics of the disc. We find that non-linear fluid effects, which reduce the effective viscosities in warped regions, can promote breaking of the disc into two distinct planes. This occurs when the Shakura & Sunyaev dimensionless viscosity parameter α is ≲0.3 and the initial angle of misalignment between the disc and hole is ≳45°. The break can be a long-lived feature, propagating outwards in the disc on the usual alignment time-scale, after which the disc is fully co-aligned or counter-aligned with the hole. Such a break in the disc may be significant in systems where we know the inclination of the outer accretion disc to the line of sight, such as some X-ray binaries: the inner disc, and so any jets, may be noticeably misaligned with respect to the orbital plane.
Disc-planet interactions in subkeplerian discs
NASA Astrophysics Data System (ADS)
Paardekooper, S.-J.
Context: One class of protoplanetary disc models, the X-wind model, predicts strongly subkeplerian orbital gas velocities, a configuration that can be sustained by magnetic tension. Aims: We investigate disc-planet interactions in these subkeplerian discs, focusing on orbital migration for low-mass planets and gap formation for high-mass planets. Methods: We use linear calculations and nonlinear hydrodynamical simulations to measure the torque and look at gap formation. In both cases, the subkeplerian nature of the disc is treated as a fixed external constraint. Results: We show that, depending on the degree to which the disc is subkeplerian, the torque on low-mass planets varies between the usual type I torque and the one-sided outer Lindblad torque, which is also negative but an order of magnitude stronger. In strongly subkeplerian discs, corotation effects can be ignored, making migration fast and inward. Gap formation near the planet's orbit is more difficult in such discs, since there are no resonances close to the planet accommodating angular momentum transport. The location of the gap is shifted inwards with respect to the planet, leaving the planet on the outside of a surface density depression. Conclusions: Depending on the degree to which a protoplanetary disc is subkeplerian, disc-planet interactions can be very different from the usual Keplerian picture, making these discs in general more hazardous for young planets.
Percutaneous Vertebroplasty in Painful Schmorl Nodes
Masala, Salvatore Pipitone, Vincenzo; Tomassini, Marco; Massari, Francesco; Romagnoli, Andrea; Simonetti, Giovanni
The Schmorl node represents displacement of intervertebral disc tissue into the vertebral body. Both Schmorl nodes and degenerative disc disease are common in the human spine. We performed a retrospective study, for the period from January 2003 to February 2005, evaluating 23 patients affected by painful Schmorl nodes, who underwent in our department percutaneous transpedicular injection of polymethylmethacrylate (vertebroplasty) in order to solve their back pain not responsive to medical and physical management. Eighteen patients reported improvement of the back pain and no one reported a worsening of symptoms. Improvement was swift and persistent in reducing symptoms. Painful Schmorl nodes, refractory to medical or physical therapy, should be considered as a new indication within those vertebral lesions adequately treatable utilizing Vertebroplasty procedure.
Clinical experience in cell-based therapeutics: disc chondrocyte transplantation A treatment for degenerated or damaged intervertebral disc.
Meisel, Hans Jörg; Siodla, Vilma; Ganey, Timothy; Minkus, Yvonne; Hutton, William C; Alasevic, Olivera J
Disc herniation treated by discectomy results in a significant loss of nucleus material and disc height. Biological restoration through the use of autologous disc chondrocyte transplantation offers a potential to achieve functional integration of disc metabolism and mechanics. Chondrocytes that have been removed from damaged cartilaginous tissues maintain a capacity to proliferate, produce and secrete matrix components and respond to physical stimuli such as dynamic loading. Nucleus regeneration using autologous cultured disc-derived chondrocytes (ADCT) has been demonstrated in a canine model and in clinical pilot studies. In 2002 a prospective, controlled, randomised, multi-center study, EuroDISC, comparing safety and efficacy of autologous disc chondrocyte transplant, chondrotransplant DISC, plus discectomy (ADCT), with discectomy alone was initiated. A dog model was used to investigate the hypothesis that autologous disc chondrocytes can be used to repair damaged intervertebral disc. Disc chondrocytes were harvested and expanded in culture under controlled and defined conditions, returned to the same animals from which they had been sampled (autologous transplantation) via percutaneous delivery. The animals were analyzed at specific times after transplantation by several methods to examine whether disc chondrocytes integrated with the surrounding tissue, produced the appropriate intervertebral disc extracellular matrix, and might provide a formative solution to disc repair. The clinical goals of the EuroDISC study, were to provide long-term pain relief, maintain disc height and prevent adjacent segment disease. Interim analysis was performed after 2 years; Oswestry (low back pain/disability), Quebec Back-Pain Disability Scale, as well as Prolo and VAS score were used for the evaluation. Disc height was assessed by MRI. In the context of degenerative changes in an injury model: () autologous disc chondrocytes were expended in culture and returned to the disc by a
Percutaneous Nephroscopic Surgery
With the development of techniques for percutaneous access and equipment to disintegrate calculi, percutaneous nephroscopic surgery is currently used by many urologists and is the procedure of choice for the removal of large renal calculi and the management of diverticula, intrarenal strictures, and urothelial cancer. Although it is more invasive than shock wave lithotripsy and retrograde ureteroscopic surgery, percutaneous nephroscopic surgery has been successfully performed with high efficiency and low morbidity in difficult renal anatomies and patient conditions. These advantages of minimal invasiveness were rapidly perceived and applied to the management of ureteropelvic junction obstruction, calyceal diverticulum, infundibular stenosis, and urothelial cancer. The basic principle of endopyelotomy is a full-thickness incision of the narrow segment followed by prolonged stenting and drainage to allow regeneration of an adequate caliber ureter. The preferred technique for a calyceal diverticulum continues to be debated. Excellent long-term success has been reported with percutaneous, ureteroscopic, and laparoscopic techniques. Each approach is based on the location and size of the diverticulum. So far, percutaneous ablation of the calyceal diverticulum is the most established minimally invasive technique. Infundibular stenosis is an acquired condition usually associated with inflammation or stones. Reported series of percutaneously treated infundibular stenosis are few. In contrast with a calyceal diverticulum, infundibular stenosis is a more difficult entity to treat with only a 50-76% success rate by percutaneous techniques. Currently, percutaneous nephroscopic resection of transitional cell carcinoma in the renal calyx can be applied in indicated cases. PMID:20495691
The Obturator Guiding Technique in Percutaneous Endoscopic Lumbar Discectomy
Han, In Ho; Cho, Won Ho; Nam, Kyoung Hyup
In conventional percutaneous disc surgery, introducing instruments into disc space starts by inserting a guide needle into the triangular working zone. However, landing the guide needle tip on the annular window is a challenging step in endoscopic discectomy. Surgeons tend to repeat the needling procedure to reach an optimal position on the annular target. Obturator guiding technique is a modification of standard endoscopic lumbar discectomy, in which, obturator is used to access triangular working zone instead of a guide needle. Obturator guiding technique provides more vivid feedback and easy manipulation. This technique decreases the steps of inserting instruments and takes safer route from the peritoneum. PMID:22639720
[Endovascular repair of iliocaval arteriovenous fistula complicating lumbar disc surgery].
Ben Jemaa, H; Maalej, A; Lazzez, K; Jemal, H; Karray, S; Ben Mahfoudh, K
Vascular complications of lumbar disc surgery are rare. Few cases have been reported. Arteriovenous fistulas are the most common. They are due to anatomical relationships between the last lumbar vertebrae, the corresponding discs, and the iliac vessels; degenerative lesions of the intervertebral discs facilitate instrumental vessel perforation, and operative difficulty. Computed tomography is particularly accurate for making the diagnosis. Treatment strategies consist in surgery or endovascular management. Percutaneous endovascular treatment using a stent-graft is a reasonable option for treating arteriovenous fistula. We describe the case of a 50-year-old patient who developed an iliocaval arteriovenous fistula following lumbar disc hernia surgery. The lesion was excluded by a stent-graft. The postoperative period was uneventful. PMID:26920402
Percutaneous endoscopic cervical discectomy using working channel endoscopes.
Ahn, Yong
Percutaneous endoscopic cervical discectomy has evolved as an efficient, minimally invasive spine surgery for cervical disc herniation or radiculopathy. The development of the working channel endoscope makes definitive decompression surgery through a percutaneous approach feasible. There are two methods of approach to target the pathology: anterior and posterior approach. The approach can be determined according to the zone of pathology or the surgeon's preference. The most significant benefits of this endoscopic surgical technique are minimal access tissue trauma and early recovery from the intervention. However, this technique is still evolving and have a steep learning curve. Extensive development of surgical technique and working channel endoscopes will enable us to treat cervical disc herniation more practically. The objective of this review is to describe the cutting-edge techniques of endoscopic surgery in the cervical spine and to discuss the pros and cons of these minimally invasive surgical techniques. PMID:27086505
ERIC Educational Resources Information Center
Barker, Philip
This discussion of the use of images in learning processes focuses on recent developments in optical storage disc technology, particularly compact disc read-only (CD-ROM) and optical video discs. Interactive video systems and user interfaces are described, and applications in education and industry in the United Kingdom are reviewed. (Author/LRW)
Diakunchak, Ihor S.
A disc seal assembly for use in a turbine engine. The disc seal assembly includes a plurality of outwardly extending sealing flange members that define a plurality of fluid pockets. The sealing flange members define a labyrinth flow path therebetween to limit leakage between a hot gas path and a disc cavity in the turbine engine.
Percutaneous absorption of drugs.
Wester, R C; Maibach, H I
The skin is an evolutionary masterpiece of living tissue which is the final control unit for determining the local and systemic availability of any drug which must pass into and through it. In vivo in humans, many factors will affect the absorption of drugs. These include individual biological variation and may be influenced by race. The skin site of the body will also influence percutaneous absorption. Generally, those body parts exposed to the open environment (and to cosmetics, drugs and hazardous toxic substances) are most affected. Treating patients may involve single daily drug treatment or multiple daily administration. Finally, the body will be washed (normal daily process or when there is concern about skin decontamination) and this will influence percutaneous absorption. The vehicle of a drug will affect release of drug to skin. On skin, the interrelationships of this form of administration involve drug concentration, surface area exposed, frequency and time of exposure. These interrelationships determine percutaneous absorption. Accounting for all the drug administered is desirable in controlled studies. The bioavailability of the drug then is assessed in relationship to its efficacy and toxicity in drug development. There are methods, both quantitative and qualitative, in vitro and in vivo, for studying percutaneous absorption of drugs. Animal models are substituted for humans to determine percutaneous absorption. Each of these methods thus becomes a factor in determining percutaneous absorption because they predict absorption in humans. The relevance of these predictions to humans in vivo is of intense research interest. The most relevant determination of percutaneous absorption of a drug in humans is when the drug in its approved formulation is applied in vivo to humans in the intended clinical situation. Deviation from this scenario involves the introduction of variables which may alter percutaneous absorption. PMID:1296607
Minimally invasive surgical procedures for the treatment of lumbar disc herniation
Lühmann, Dagmar; Burkhardt-Hammer, Tatjana; Borowski, Cathleen; Raspe, Heiner
option between conservative and operative management of small lumbar disc herniations or protrusions causing sciatica. Two RCT comparing transforaminal endoscopic procedures with microdiscectomy in patients with sciatica and small non-sequestered disc herniations show comparable short and medium term overall success rates. Concerning speed of recovery and return to work a trend towards more favourable results for the endoscopic procedures is noted. It is doubtful though, whether these results from the eleven and five years old studies are still valid for the more advanced procedures used today. The only RCT comparing the results of automated percutaneous lumbar discectomy to those of microdiscectomy showed clearly superior results of microdiscectomy. Furthermore, success rates of automated percutaneous lumbar discectomy reported in the RCT (29%) differ extremely from success rates reported in case series (between 56% and 92%). The literature search retrieves no controlled trials to assess efficacy and/or effectiveness of laser-discectomy, percutaneous manual discectomy or endoscopic procedures using a posterior approach in comparison to the standard procedures. Results from recent case series permit no assessment of efficacy, especially not in comparison to standard procedures. Due to highly selected patients, modi-fications of operative procedures, highly specialised surgical units and poorly standardised outcome assessment results of case series are highly variable, their generalisability is low. The results of the five economical analyses are, due to conceptual and methodological problems, of no value for decision-making in the context of the German health care system. Discussion Aside from low methodological study quality three conceptual problems complicate the interpretation of results. Continuous further development of technologies leads to a diversity of procedures in use which prohibits generalisation of study results. However, diversity is noted not only for
Early experience with percutaneous lateral discectomy.
Stern, M B
Seventeen patients were treated by percutaneous lumbar discectomy for a herniated disc and sciatica. The criteria for inclusion in this series included: (1) a protruding disc in the lumbar area causing neural compression; (2) persistent sciatica; (3) failure of conservative treatment; (4) magnetic resonance imaging, computer tomographic, or myelographic confirmation of the protrusion; and (5) chronic low-back pain with definite evidence of a protruding disc at the appropriate level. The only contraindication to the procedure is the presence of an extruded fragment. There were ten male and seven female patients, with an average age of 40 years. The operation was performed under local anesthesia and by the method of Hijikata. Six cases were at L5-S1, nine at L4-L5, four at L3-L4, and one at L2-L3. Fourteen of 16 patients were relieved of their symptoms. One operation was aborted due to the inability to pass the cannula beneath arthritic facet joints. One complication occurred early while using general anesthetic. An L5 nerve root was injured, causing a permanent drop foot. Major possible complications include infection, nerve root injury, and vascular injury. The success rate with an average follow-up period of six and one-half months was 87.5%. PMID:2910618
Optical Coherence Tomography Angiography of Optic Disc Perfusion in Glaucoma
Jia, Yali; Wei, Eric; Wang, Xiaogang; Zhang, Xinbo; Morrison, John C.; Parikh, Mansi; Lombardi, Lori H.; Gattey, Devin M.; Armour, Rebecca L.; Edmunds, Beth; Kraus, Martin F.; Fujimoto, James G.; Huang, David
Purpose To compare optic disc perfusion between normal and glaucoma subjects using optical coherence tomography (OCT) angiography and detect optic disc perfusion changes in glaucoma. Design Observational, cross-sectional study. Participants Twenty-four normal subjects and 11 glaucoma patients were included. Methods One eye of each subject was scanned by a high-speed 1050 nm wavelength swept-source OCT instrument. The split-spectrum amplitude-decorrelation angiography algorithm (SSADA) was used to compute three-dimensional optic disc angiography. A disc flow index was computed from four registered scans. Confocal scanning laser ophthalmoscopy (cSLO) was used to measure disc rim area, and stereo photography was used to evaluate cup/disc ratios. Wide field OCT scans over the discs were used to measure retinal nerve fiber layer (NFL) thickness. Main Outcome Measurements Variability was assessed by coefficient of variation (CV). Diagnostic accuracy was assessed by sensitivity and specificity. Comparisons between glaucoma and normal groups were analyzed by Wilcoxon rank-sum test. Correlations between disc flow index, structural assessments, and visual field (VF) parameters were assessed by linear regression. Results In normal discs, a dense microvascular network was visible on OCT angiography. This network was visibly attenuated in glaucoma subjects. The intra-visit repeatability, inter-visit reproducibility, and normal population variability of the optic disc flow index were 1.2%, 4.2%, and 5.0% CV respectively. The disc flow index was reduced by 25% in the glaucoma group (p = 0.003). Sensitivity and specificity were both 100% using an optimized cutoff. The flow index was highly correlated with VF pattern standard deviation (R2 = 0.752, p = 0.001). These correlations were significant even after accounting for age, cup/disc area ratio, NFL, and rim area. Conclusions OCT angiography, generated by the new SSADA algorithm, repeatably measures optic disc perfusion. OCT
Structural Raman enhancement in graphite nano-discs
NASA Astrophysics Data System (ADS)
Cardenas, J. F.; Chakarov, D.; Kasemo, B.
Raman scattering in disc-shaped graphite nanostructures, etched out of bulk HOPG, are investigated using an excitation wavelength of 532 nm at different laser power. The G-band is fitted using two Lorentzian functions, GL and GH. The difference of Raman shift between the two Lorentzian functions increase with laser power as a consequence of selective absorption and heating of the discs. Further, the G-band from the nanostructured HOPG reveal a Raman enhancement (RE) of ~2.2 and ~1.5 for the components associated with the discs (GL) and the supporting substrate (GH), respectively. The quantitative agreement between the experimental results and performed finite difference time domain calculations make possible to conclude that electromagnetic energy penetrates considerably into the discs from the circular periphery probably due to multiple scattering. In addition, the dependence of RE of the GL component on the laser power is attributed to a temperature dependent electron-phonon coupling.
Percutaneous Biopsy of Osteoid Osteomas Prior to Percutaneous Treatment Using Two Different Biopsy Needles
Laredo, Jean-Denis Hamze, Bassam; Jeribi, Riadh
Biopsy is usually performed as the first step in percutaneous treatment of osteoid osteomas prior to laser photocoagulation. At our institution, 117 patients with a presumed diagnosis of osteoid osteoma had a trephine biopsy before a percutaneous laser photocoagulation. Biopsies were made using two different types of needles. A Bonopty biopsy needle (14-gauge cannula, 16-gauge trephine needle; Radi Medical Systems, Uppsala, Sweden) was used in 65 patients, and a Laurane biopsy needle (11-gauge cannula, 12.5-gauge trephine needle; Laurane Medical, Saint-Arnoult, France) in 43 patients. Overall biopsy results were positive for osteoid osteoma in 83 (70.9%) of the 117 cases. The Laurane needle provided a significantly higher positive rate (81.4%) than the Bonopty needle (66.1%; p < 0.05). This difference was not due to the size of the nidus, which was similar in the two groups (p < 0.05) and may be an effect of differences in needle caliber (12.5 vs. 14 gauge) as well as differences in needle design. The rate of positive biopsy results obtained in the present series with the Laurane biopsy needle is, to our knowledge, the highest rate reported in series dealing with percutaneous radiofrequency ablation and laser photocoagulation of osteoid osteomas.
Precision diagnostic disc injections.
Fortin, J D
Spinal pain is an important public health problem affecting the population indiscriminately. The structures responsible for pain in the spine include the vertebrae, intervertebral discs, spinal cord, nerve roots, facet joints, ligaments, muscles, atlanto-occipital joints, atlanto-axial joints, and sacroiliac joints. Even though disc herniation, facet joints, strained muscles, and torn ligaments have been attributed to be the cause of most spinal pain, either in the neck and upper extremities, upper and mid back, or low back and lower extremities, disorders of the disc other than disc herniation have been implicated more frequently than any other disorders. Once stifled by misinformation, discography now has applications in a number of clinical settings. While cervical and lumbar discography is well studied and well known, thoracic discography is in its nascent stages of clinical application. The value of discography lies in its ability to produce pain and thereby identify a "pain generator." This allows treatment to be based on the specific cause of pain. The three primary components of diagnostic disc injection are: provocation/analgesia, discometry, and nucleography. Despite the recent exponential growth of noninvasive spinal technology, diagnostic disc injection remains the sole direct method for definitively determining whether a disc is a physiological pain generator. It is clear that discography is a safe and powerful complement to the overall clinical context. PMID:16906185
ERIC Educational Resources Information Center
Schewe, Phillip F.
Examines the nature of laser light. Topics include: (1) production and characteristics of laser light; (2) nine types of lasers; (3) five laser techniques including holography; (4) laser spectroscopy; and (5) laser fusion and other applications. (SK)
Minimally invasive percutaneous endoscopic 2 levels adjacent lumbar discectomy through 1 portal skin incision: Preliminary study
Kim, Hyeun Sung; Ju, Chang Il; Kim, Seok Won; Kim, Jong Gyue; Lee, Seung Myung; Kim, Byoung Wook
Background: Acute lumbar disc herniation can occur in every lumbar intervertebral disc space and in multiple levels simultaneously. In the cases of 2 levels adjacent lumbar disc herniations of severe unilateral radiculopathic leg pain caused by compression of the nerve roots, respectively, multiple incision or long incision is generally needed for simultaneous removal of disc fragment in 2 levels. Objectives: We proposed the minimally invasive one portal skin incision endoscopic discectomy is effective and safe method to treat 2 levels adjacent lumbar disc herniation. Materials and Methods: We have experimented total 8 cases of 2 levels adjacent lumbar disc herniation having unilateral radiculopathic pain respectively. All cases are 2 levels adjacent lumbar disc herniation. We have tried a percutaneous endoscopic transforaminal approach through minimal one portal skin incision and remove the two herniated disc materials in the adjacent levels. Results: The L2-L3 level was involved in 2 patients, L3-L4 level in 6 patients, while the L4-L5 level was involved in 7 patients, L5-S1 level in 1 patient. The mean follow-up was 18.5 months. The mean visual analogue score (VAS) of the patients prior to surgery was 7.75, and the mean postoperative VAS was 2.375. According to Macnab's criteria, 3 patients had excellent results, 4 patients had good results, 1 patient had fair results, and no patient had a poor result; satisfactory results were obtained in 87.5% of the cases. Conclusion: The percutaneous endoscopic transforaminal approach through 1 skin portal incision could be effective surgical method in unilateral adjacent 2 levels lumbar disc herniation. PMID:25972937
Twenty-Layer Optical Disc Fabricated by Web Coating and Lamination
NASA Astrophysics Data System (ADS)
Mikami, Tatsuo; Mochizuki, Hidehiro; Sasaki, Toshio; Kitahara, Toshiyuki; Tsuyama, Hiroaki; Inoue, Kenichirou; Ito, Masaharu
We developed a new fabrication method for multilayer optical discs for the high-throughput production of such discs. We used web coating and lamination to prepare a stacked unit. The stacked unit was a layered structure consisting of a recording layer, a UV resin layer, a recording layer, and a pressure-sensitive adhesive layer. We obtained a 20-layer disc simply by laminating the stacked units 10 times. The transmittance of the 20 recording layers was 87% owing to the high transparency of the two-photon recording material. A scanning electron microscopy (SEM) image of the disc showed a clear multilayer structure. The recording layers of the disc were recorded using a pulse laser without interlayer cross write. The thickness variation of the transparent part of the disc was within +/-2 µm, and the tilt angles of the disc satisfied the Blu-ray disc (BD) specifications.
Product and process for manufacturing an optical disc master
Dobbin, R.B.; Loeppky, D.G.; Norton, J.R.; Del Mar, B.E.
The invention discloses a simplified four step process for making an optical disc master or alternatively a WORM disc by first making or obtaining a transparent polymer disc with a tracking groove of desired geometry molded therein, then spin coating an optically active lamina on the grooved side of the disc, then recording data on said polymer disc with groove controlled and tracked laser means by ablating active lamina, forming pits, the shape of which is determined by the groove geometry and finally depositing a conductive and reflective lamina over the pitted active lamina. To change the OD master to an OD WORM, a protective cover is added to the electrically conductive and optically reflective lamina. 12 figs.
... 50. A herniated lumbar disc may also cause back pain, although back pain alone (without leg pain) can have many causes ... 90% success); surgery is less effective in relieving back pain. Nonsurgical treatment Your doctor may prescribe nonsurgical treatments ...
Sedation Monitoring and Management during Percutaneous Endoscopic Lumbar Discectomy.
Oksar, Menekse; Gumus, Tulin; Kanbak, Orhan
Percutaneous endoscopic laser discectomy (PELD) is a painful intervention that requires deep sedation and analgesia. However, sedation should be light at some point because cooperation by the patient during the procedure is required for successful surgical treatment. Light sedation poses a problem for endotracheal intubation, while patients placed in the prone position during percutaneous endoscopic discectomy pose a problem for airway management. Therefore, under these conditions, sedation should be not deeper than required. Here we report the sedation management of three cases that underwent PELD, with a focus on deep and safe sedation that was monitored using bispectral index score and observer's assessment of alertness/sedation score. PMID:27298743
Sedation Monitoring and Management during Percutaneous Endoscopic Lumbar Discectomy
Oksar, Menekse; Gumus, Tulin; Kanbak, Orhan
Percutaneous endoscopic laser discectomy (PELD) is a painful intervention that requires deep sedation and analgesia. However, sedation should be light at some point because cooperation by the patient during the procedure is required for successful surgical treatment. Light sedation poses a problem for endotracheal intubation, while patients placed in the prone position during percutaneous endoscopic discectomy pose a problem for airway management. Therefore, under these conditions, sedation should be not deeper than required. Here we report the sedation management of three cases that underwent PELD, with a focus on deep and safe sedation that was monitored using bispectral index score and observer's assessment of alertness/sedation score. PMID:27298743
Percutaneous absorption from soil.
Andersen, Rosa Marie; Coman, Garrett; Blickenstaff, Nicholas R; Maibach, Howard I
Abstract Some natural sites, as a result of contaminants emitted into the air and subsequently deposited in soil or accidental industrial release, have high levels of organic and non-organic chemicals in soil. In occupational and recreation settings, these could be potential sources of percutaneous exposure to humans. When investigating percutaneous absorption from soil - in vitro or vivo - soil load, particle size, layering, soil "age" time, along with the methods of performing the experiment and analyzing the results must be taken into consideration. Skin absorption from soil is generally reduced compared with uptake from water/acetone. However, the absorption of some compounds, e.g., pentachlorophenol, chlorodane and PCB 1254, are similar. Lipophilic compounds like dichlorodiphenyltrichloroethane, benzo[A]pyrene, and metals have the tendency to form reservoirs in skin. Thus, one should take caution in interpreting results directly from in vitro studies for risk assessment; in vivo validations are often required for the most relevant risk assessment. PMID:25205703
Percutaneous transluminal coronary angioplasty (PTCA)
MedlinePlus Videos and Cool Tools
Percutaneous transluminal coronary angioplasty (PTCA) is a minimally invasive procedure to open up blocked coronary arteries, allowing blood to circulate unobstructed to the heart muscle. The procedure ...
Superresolution technology applied to optical discs
NASA Astrophysics Data System (ADS)
Zhou, Changhe; Luo, Hongxin
Smaller focal points are essential for the development of the next-generation optical disc. The size of focal point depends on the diffraction effect that is dependant on the numerical aperture of a lens and the wavelength of light. However, increase of the numerical aperture and decrease of the light wavelength will be ultimately limited due to the technical difficulty of fabricating a too-high NA lens and the too-short wavelength laser. In this paper, we report another approach of using the superresolution technology to compress the size of the so-called Airy spot for the next-generation optical disc, which is independent on the wavelength of laser. The superresolution phase plates are designed and fabricated with a microoptics technique. When such a phase plate is inserted into the optical system, the central spot at the focal plane of a lens is decreased to be 0.8 times of the Airy pattern, implying the possibility of reading higher storage density of optical discs. The most attractive feature is that the phase plate can be mass-produced at a very low cost, compared with the high cost of the high-numerical lens and/or the short wavelength laser. The disadvantages are that the inserted phase plate will induce the slight circular sidelobes around the central sport, so that it consumes a little more laser energy. The shortcoming could be overcome with suitable amendment. We have fabricated the phase plates with the surface-relief profile on a normal glass for phase modulation. Experimental results of superresolution effect with a low numerical aperture (NA=0.1) and a high-numerical lens (NA=0.8) are reported, which are in good agreement with the theoretical prediction. Superresolution technique should be highly interesting as a novel technique of the next-generation pickup head for reading the high storage of the optical discs.
Percutaneous transmyocardial revascularization.
Kim, C B; Oesterle, S N
Transmyocardial revascularization (TMR) is a potential therapy for patients with severe angina pectoris and coronary anatomy deemed unsuitable for traditional revascularization techniques. Investigations of TMR are reviewed with emphasis on studies relevant to the development of a percutaneous, catheter-based transmyocardial revascularization procedure (PMR). The results of the preliminary animal studies and description of the PMR procedure are discussed. The recently initiated human PMR protocol is summarized and possible future investigative directions are outlined. PMID:9641086
Cement Leakage into Adjacent Vertebral Body Following Percutaneous Vertebroplasty
Park, Jae Hoo; Kim, Hyeun Sung
Percutaneous vertebroplasty (PV) is a minimally invasive procedure for osteoporotic vertebral compression fractures that fail to respond to conventional conservative treatment. It significantly improves intolerable back pain within hours, and has a low complication rate. Although rare, PV is not free of complications, most of which are directly related to cement leakage. Because of its association with new adjacent fracture, the importance of cement leakage into the adjacent disc space is paramount. Here, we report an interesting case of cement leakage into the adjacent upper vertebral body as well as disc space following PV. To the best of our knowledge, there has been no report of cement leakage into the adjacent vertebral body following PV. This rare case is presented along with a review of the literature. PMID:27437018
Protective Effects of Cannabidiol on Lesion-Induced Intervertebral Disc Degeneration
Silveira, João W.; Issy, Ana Carolina; Castania, Vitor A.; Salmon, Carlos E. G.; Nogueira-Barbosa, Marcello H.; Guimarães, Francisco S.; Defino, Helton L. A.; Bel, Elaine Del
Disc degeneration is a multifactorial process that involves hypoxia, inflammation, neoinnervation, accelerated catabolism, and reduction in water and glycosaminoglycan content. Cannabidiol is the main non-psychotropic component of the Cannabis sativa with protective and anti-inflammatory properties. However, possible therapeutic effects of cannabidiol on intervertebral disc degeneration have not been investigated yet. The present study investigated the effects of cannabidiol intradiscal injection in the coccygeal intervertebral disc degeneration induced by the needle puncture model using magnetic resonance imaging (MRI) and histological analyses. Disc injury was induced in the tail of male Wistar rats via a single needle puncture. The discs selected for injury were punctured percutaneously using a 21-gauge needle. MRI and histological evaluation were employed to assess the results. The effects of intradiscal injection of cannabidiol (30, 60 or 120 nmol) injected immediately after lesion were analyzed acutely (2 days) by MRI. The experimental group that received cannabidiol 120 nmol was resubmitted to MRI examination and then to histological analyses 15 days after lesion/cannabidiol injection. The needle puncture produced a significant disc injury detected both by MRI and histological analyses. Cannabidiol significantly attenuated the effects of disc injury induced by the needle puncture. Considering that cannabidiol presents an extremely safe profile and is currently being used clinically, these results suggest that this compound could be useful in the treatment of intervertebral disc degeneration. PMID:25517414
Percutaneous nephrolithotomy for pediatric urolithiasis
Ganpule, Arvind P.; Mishra, Shashikant; Desai, Mahesh R.
Pediatric urolithiasis is a management dilemma as a number of treatment options are available such as shock wave lithotripsy (SWL), percutaneous nephrolithotomy (PCNL), and retrograde intrarenal surgery (RIRS). PCNL offers good clearance rates in a single hospital stay. The concerns with PCNL include the use of large instrument in pediatric kidneys, parenchymal damage and the associated effects on renal function, radiation exposure with fluoroscopy, and the risk of major complications including sepsis and bleeding. Evolution of pediatric PCNL technique such as miniaturization of instruments, limitation of tract size and advanced intracorporeal lithotripters have resulted in this technique being widely utilized for achieving stone-free status in appropriate patients. Many of the patients in our country come from remote areas thereby requiring special considerations during treatment. This also necessitates complete clearance in a single shorter hospital stay. PCNL appears to be the optimal option available in this scenario. The literature suggests that even complex and staghorn calculi can be tackled with this approach. The choice of the method to gain access is a matter of experience and personal preference. Ultrasound offers the advantage of visualization of spleen, liver and avoids injury. Miniaturization of instruments, particularly smaller nephroscopes and the potential to use lasers will decrease the morbidity and improve the clearance rates further. In this article, we analyze the management of pediatric urolithiasis with PCNL. We discuss our technique and analyze the results, complications and technique mentioned in the contemporary literature. PMID:21369389
Intradiscal injection of oxygen-ozone gas mixture for the treatment of cervical disc herniations.
Alexandre, A; Corò, L; Azuelos, A; Buric, J; Salgado, H; Murga, M; Marin, F; Giocoli, H
For disc herniations the use of open surgical approaches is reduced since new percutaneous methods allowing shrinkage of the disc and improvement of the radicular function are gaining interest. Studies on the spontaneous disappearance of disc fragments have demonstrated autoimmune responses with a chronic inflammatory reaction. Also radicular pain has been shown to be mostly due to biochemical mechanisms. Researchers in different fields surprisingly noticed that a brief, calculated, oxidative stress by ozone administration may correct a persistent imbalance due to excessive, chronic oxidative injury. Oxygen-ozone gas injection in painful patients has a dramatic effect on clinical symptoms. On these bases the intradiscal injection of oxygen-ozone gas has been conceived. We report the treatment on a series of patients affected by cervical disc pathology, treated by intradiscal injection of oxygen-ozone gas mixture. The effects both on pain and on radicular dysfunction are impressive. The morphological effect of the treatment was also evaluated by pathological examination. PMID:15830973
[CT-controlled percutaneous lumbar discectomy in therapy of radicular pain].
Lierz, P; Felleiter, P; Alo, K
Percutaneous disc decompression using the Decompressor system is another treatment option for patients suffering from chronic discogenic leg pain. This is the first report on a patient undergoing this procedure under CT-control. A 49 year old man with radicular leg pain showed significant pain reduction after percutaneus decompression of a discal herniation at the L4/5 level. The new system enables qualitative and quantitative measures of the removed disc material. CT-control ensures exact positioning of the device. PMID:15770562
The ProDisc artificial disc: insertion technique.
Aryan, Henry E; Acosta, Frank L; Ames, Christopher P
The ProDisc artificial lumbar disc was designed for use in treatment of degenerative lumbar disease. The disc is implanted using an anterior approach to the lumbar spine with the assistance of intraoperative fluoroscopy. A variety of insertion instruments guide the surgeon through this process. The disc is implanted via an anterior approach, generally retroperitoneally but on occasion transperitoneally. The different approaches and insertion technique are described in this article. PMID:16326288
Nanostructured diamond-like carbon on digital versatile disc as a matrix-free target for laser desorption/ionization mass spectrometry.
Najam-ul-Haq, Muhammad; Rainer, Matthias; Huck, Christian W; Hausberger, Peter; Kraushaar, Harald; Bonn, Günther K
A nanostructured diamond-like carbon (DLC) coated digital versatile disk (DVD) target is presented as a matrix-free sample support for application in laser desorption/ionization mass spectrometry (LDI-MS). A large number of vacancies, defects, relative sp(2) carbon content, and nanogrooves of DLC films support the LDI phenomenon. The observed absorptivity of DLC is in the range of 305-330 nm (nitrogen laser, 337 nm). The universal applicability is demonstrated through different analytes like amino acids, carbohydrates, lipids, peptides, and other metabolites. Carbohydrates and amino acids are analyzed as sodium and potassium adducts. Peptides are detectable in their protonated forms, which avoid the extra need of additives for ionization. A bovine serum albumin (BSA) digest is analyzed to demonstrate the performance for peptide mixtures, coupled with the material-enhanced laser desorption/ionization (MELDI) approach. The detection limit of the described matrix-free target is investigated to be 10 fmol/microL for [Glu(1)]-fibrinopeptide B (m/z 1570.6) and 1 fmol/microL for L-sorbose (Na(+) adduct). The device does not require any chemical functionalization in contrast to other matrix-free systems. The inertness of DLC provides longer lifetimes without any deterioration in the detection sensitivity. Broad applicability allows high performance analysis in metabolomics and peptidomics. Furthermore the DLC coated DVD (1.4 GB) sample support is used as a storage device for measured and processed data together with sampling on a single device. PMID:18729472
Percutaneous Pulmonary Valve Placement
Prieto, Lourdes R.
Patients with congenital heart disease and pulmonary valve disease need multiple procedures over their lifetimes to replace their pulmonary valves. Chronic pulmonary stenosis, regurgitation, or both have untoward effects on ventricular function and on the clinical status of these patients. To date, all right ventricle–pulmonary artery conduits have had relatively short lifespans. Percutaneous pulmonary valve implantation, although relatively new, will probably reduce the number of operative procedures that these patients will have to undergo over a lifetime. Refinement and further development of this procedure holds promise for the extension of this technology to other patient populations. PMID:26175629
Percutaneous left ventricular restoration.
Ige, Mobolaji; Al-Kindi, Sadeer G; Attizzani, Guilherme; Costa, Marco; Oliveira, Guilherme H
The ventricular partitioning device known as Parachute is the first and only percutaneously implantable device aimed at restoration of normal left ventricular geometry in humans. Since its conception, this technology has undergone extensive animal and human testing, with proved feasibility and safety, and is currently being studied in a pivotal randomized clinical trial. This article discusses ventricular remodeling and therapies attempted in the past, details the components of the ventricular partitioning device, describes the implanting technique, and reviews the most current experience of this device in humans. PMID:25834974
The Chemistry of Optical Discs.
ERIC Educational Resources Information Center
Birkett, David
Explains the chemistry used in compact discs (CD), digital versatile discs (DVD), and magneto-optical (MO) discs focusing on the steps of initial creation of the mold, the molding of the polycarbonate, the deposition of the reflective layers, the lacquering of the CDs, and the bonding of DVDs. (Contains 15 references.) (YDS)
NASA Astrophysics Data System (ADS)
Dogan, Suzan
Accretion discs are common in binary systems, and they are often found to be misaligned with respect to the binary orbit. The gravitational torque from a companion induces nodal precession in misaligned disc orbits. In this study, we first calculate whether this precession is strong enough to overcome the internal disc torques communicating angular momentum. We compare the disc precession torque with the disc viscous torque to determine whether the disc should warp or break. For typical parameters precession wins: the disc breaks into distinct planes that precess effectively independently. To check our analytical findings, we perform 3D hydrodynamical numerical simulations using the PHANTOM smoothed particle hydrodynamics code, and confirm that disc breaking is widespread and enhances accretion on to the central object. For some inclinations, the disc goes through strong Kozai cycles. Disc breaking promotes markedly enhanced and variable accretion and potentially produces high-energy particles or radiation through shocks. This would have significant implications for all binary systems: e.g. accretion outbursts in X-ray binaries and fuelling supermassive black hole (SMBH) binaries. The behaviour we have discussed in this work is relevant to a variety of astrophysical systems, for example X-ray binaries, where the disc plane may be tilted by radiation warping, SMBH binaries, where accretion of misaligned gas can create effectively random inclinations and protostellar binaries, where a disc may be misaligned by a variety of effects such as binary capture/exchange, accretion after binary formation.
ERIC Educational Resources Information Center
Ucke, C.; Schlichting, H-J.
Snap discs made of bimetal have many technical applications as thermostats. Jumping discs are a toy version of such snap discs. Besides giving technical information, we describe physical investigations. We show especially how, through simple measurements and calculations, you can determine the initial speed ([approximately equal to]3.5 m…
ERIC Educational Resources Information Center
Desmarais, Norman
Presents a comparison of two types of compact disc (CD-ROM) foreign language tutorials: (1) those made by publishers who favor an immersion approach; and (2) those made by publishers who use grammar-based approaches. Both types of CD-ROMs address various age groups, skill levels, and learning styles. (JMV)
NASA Astrophysics Data System (ADS)
Elliott, John R.; Baxter, Stephen
D.I.S.C: Decipherment Impact of a Signal's Content. The authors present a numerical method to characterise the significance of the receipt of a complex and potentially decipherable signal from extraterrestrial intelligence (ETI). The purpose of the scale is to facilitate the public communication of work on any such claimed signal, as such work proceeds, and to assist in its discussion and interpretation. Building on a "position" paper rationale, this paper looks at the DISC quotient proposed and develops the algorithmic steps and comprising measures that form this post detection strategy for information dissemination, based on prior work on message detection, decipherment. As argued, we require a robust and incremental strategy, to disseminate timely, accurate and meaningful information, to the scientific community and the general public, in the event we receive an "alien" signal that displays decipherable information. This post-detection strategy is to serve as a stepwise algorithm for a logical approach to information extraction and a vehicle for sequential information dissemination, to manage societal impact. The "DISC Quotient", which is based on signal analysis processing stages, includes factors based on the signal's data quantity, structure, affinity to known human languages, and likely decipherment times. Comparisons with human and other phenomena are included as a guide to assessing likely societal impact. It is submitted that the development, refinement and implementation of DISC as an integral strategy, during the complex processes involved in post detection and decipherment, is essential if we wish to minimize disruption and optimize dissemination.
ERIC Educational Resources Information Center
Laurillard, Diana
Reports an evaluation of the Teddy Bear disc, an interactive videodisc developed at the Open University for a second-level course in metallurgy and materials technology. Findings from observation of students utilizing the videodisc are reviewed; successful design features and design problems are considered; and development costs are outlined. (MBR)
[Ultrasound guided percutaneous nephrolithotripsy].
Guliev, B G
The study was aimed to the evaluation of the effectiveness and results of ultrasound guided percutaneous nephrolithotripsy (PNL) for the treatment of patients with large stones in renal pelvis. The results of PNL in 138 patients who underwent surgery for kidney stones from 2011 to 2013 were analyzed. Seventy patients (Group 1) underwent surgery with combined ultrasound and radiological guidance, and 68 patients (Group 2)--only with ultrasound guidance. The study included patients with large renal pelvic stones larger than 2.2 cm, requiring the formation of a single laparoscopic approach. Using the comparative analysis, the timing of surgery, the number of intra- and postoperative complications, blood loss and length of stay were evaluated. Percutaneous access was successfully performed in all patients. Postoperative complications (exacerbation of chronic pyelonephritis, gross hematuria) were observed in 14.3% of patients in Group 1 and in 14.7% of patients in Group 2. Bleeding requiring blood transfusion, and injuries of adjacent organs were not registered. Efficacy of PNL in the Group 1 was 95.7%; 3 (4.3%) patients required additional interventions. In Group 2, the effectiveness of PNL was 94.1%, 4 (5.9%) patients additionally underwent extracorporeal lithotripsy. There were no significant differences in the effectiveness of PNL, the volume of blood loss and duration of hospitalization. Ultrasound guided PNL can be performed in large pelvic stones and sufficient expansion of renal cavities, thus reducing radiation exposure of patients and medical staff. PMID:25807772
Elective Percutaneous Coronary Intervention
Madani, Mohsen; Alizadeh, Keivan; Ghazaee, Sepideh Parchami; Zavarehee, Abbas; Abdi, Seifollah; Shakerian, Farshad; Salehi, Negar; Firouzi, Ata
Regardless of the diabetic status of patients with coronary artery disease, hyperglycemia and hypoglycemia are adversely associated with cardiovascular events. The relationship between glucose levels and increased mortality risk in acute myocardial infarction has been shown through various glucose metrics; however, there is a dearth of multivariate analysis of the relationship between elective coronary angioplasty and preprocedural blood glucose levels. We evaluated the relationship between preprocedural blood glucose levels and myocardial injury in 1,012 consecutive patients who underwent elective percutaneous coronary angioplasty. The patients were classified into 4 glycemic groups on the basis of blood glucose levels measured immediately before the procedure: hypoglycemic, euglycemic, mildly hyperglycemic, and hyperglycemic. Samples for troponin I and creatine kinase–MB fraction were collected before each procedure and at 8, 16, and 24 hours after each procedure. Bivariate analysis revealed that postprocedural troponin I levels were significantly higher in the hyperglycemic group (P=0.027). Although postprocedural levels of creatine kinase–MB fraction rose insignificantly in the hypoglycemic patients, our results showed that these patients were more likely to have postprocedural levels 2 to 5 times the upper limit of normal (P=0.013). We tentatively conclude that abnormally low preprocedural plasma glucose levels—together with a recent history of smoking—are associated with an increased incidence of periprocedural myocardial injury in patients undergoing elective percutaneous coronary intervention. PMID:24082370
Laser beam alignment apparatus and method
Gruhn, Charles R.; Hammond, Robert B.
The disclosure relates to an apparatus and method for laser beam alignment. Thermoelectric properties of a disc in a laser beam path are used to provide an indication of beam alignment and/or automatic laser alignment.
Laser beam alignment apparatus and method
Gruhn, C.R.; Hammond, R.B.
The disclosure related to an apparatus and method for laser beam alignment. Thermoelectric properties of a disc in a laser beam path are used to provide an indication of beam alignment and/or automatic laser alignment.
Clinical Outcomes of Percutaneous Endoscopic Surgery for Lumbar Discal Cyst
Ha, Sang Woo; Kim, Seok Won; Lee, SeungMyung; Kim, Yong Hyun; Kim, Hyeun Sung
Objective Discal cyst is rare and causes indistinguishable symptoms from lumbar disc herniation. The clinical manifestations and pathological features of discal cyst have not yet been completely known. Discal cyst has been treated with surgery or with direct intervention such as computed tomography (CT) guided aspiration and steroid injection. The purpose of this study is to evaluate the safety and efficacy of the percutaneous endoscopic surgery for lumbar discal cyst over at least 6 months follow-up. Methods All 8 cases of discal cyst with radiculopathy were treated by percutaneous endoscopic surgery by transforaminal approach. The involved levels include L5-S1 in 1 patient, L3-4 in 2, and L4-5 in 5. The preoperative magnetic resonance imaging and 3-dimensional CT with discogram images in all cases showed a connection between the cyst and the involved intervertebral disc. Over a 6-months period, self-reported measures were assessed using an outcome questionaire that incorporated total back-related medical resource utilization and improvement of leg pain [visual analogue scale (VAS) and Macnab's criteria]. Results All 8 patients underwent endoscopic excision of the cyst with additional partial discectomy. Seven patients obtained immediate relief of symptoms after removal of the cyst by endoscopic approach. There were no recurrent lesions during follow-up period. The mean preoperative VAS for leg pain was 8.25±0.5. At the last examination followed longer than 6 month, the mean VAS for leg pain was 2.25±2.21. According to MacNab' criteria, 4 patients (50%) had excellent results, 3 patients (37.5%) had good results; thus, satisfactory results were achieved in 7 patients (87.5%). However, one case had unsatisfactory result with persistent leg pain and another paresthesia. Conclusion The radicular symptoms were remarkably improved in most patients immediately after percutaneous endoscopic cystectomy by transforaminal approach. PMID:22737300
Coulomb attraction in optical spectra of quantum discs
NASA Astrophysics Data System (ADS)
Adolph, B.; Glutsch, S.; Bechstedt, F.
We present a theory which describes the influence of the Coulomb interaction on the optical spectra of quantum discs within the envelope function formalism. Starting from a non-local Elliott formula luminescence is traced back to two-particle wave functions and energies. They are solutions of the corresponding Schrödinger equation for an electron-hole pair under the influence of the Coulomb attraction and confinement potentials determined by the spatial variation of the band edges of the considered microstructure. We present a complete numerical solution of the two-particle problem for flat quantum dots, i.e. discs for which the size quantization in growth direction is much stronger than that in the xy-plane. We discuss two different situations, single discs with infinite and finite confinement potentials. Resulting theoretical lineshapes are compared with luminescence spectra obtained recently for quantum discs fabricated by laser-induced thermal cation interdiffusion in quantum-well structures.
High-density optical discs for audio, video, and image applications
NASA Astrophysics Data System (ADS)
Gan, Fuxi; Hou, Lisong
Great progress in optical storage has taken place in the last decade. The development of optical discs is always towards higher and higher storage density and data transfer rate in order to meet the ever-increasing requirements of applications in audio, video and image areas. It has been proved a logical and effective approach to employ laser light of shorter wavelength and lenses of higher numerical aperture for increasing storage density, as is shown by the evolution of optical disc from CD family to DVD family. At present, research and development of high density DVD (HD-DVD), blu-ray disc and advanced storage magneto-optical (AS-MO) disc are carried out very extensively. Meanwhile, miniaturization of disc size and use of multiplication techniques to increase the storage density and capacity have already given rise to new formats such as iD Photo disc and Data Play disc as well as multi-layer discs. Digital holographic storage (DHS) disc is also one of the research and development subjects of many companies and research institutions. Some new concept optical storage such as fluorescent multiplayer disc (FMD) is also under intensive development. All these have greatly promoted applications of optical discs in audio, video and image devices.
Percutaneously inserted central catheter - infants
PICC - infants; PQC - infants; Pic line - infants; Per-Q cath - infants ... A percutaneously inserted central catheter (PICC) is a long, very thin, soft plastic tube that is put into a small blood vessel. This article addresses PICCs in ...
Percutaneous Pulmonary Valve Implantation
Lee, Hyoung-Doo
Pulmonary regurgitation (PR) is a frequent sequelae after repair of tetralogy of Fallot, pulmonary atresia, truncus arteriosus, Rastelli and Ross operation. Due to patient growth and conduit degeneration, these conduits have to be changed frequently due to regurgitation or stenosis. However, morbidity is significant in these repeated operations. To prolong conduit longevity, bare-metal stenting in the right ventricular outflow tract (RVOT) obstruction has been performed. Stenting the RVOT can reduce the right ventricular pressure and symptomatic improvement, but it causes PR with detrimental effects on the right ventricle function and risks of arrhythmia. Percutaneous pulmonary valve implantation has been shown to be a safe and effective treatment for patients with pulmonary valve insufficiency, or stenotic RVOTs. PMID:23170091
Percutaneous Sacroiliac Screw Technique.
Tidwell, John; Cho, Rosa; Reid, J Spence; Boateng, Henry; Copeland, Carol; Sirlin, Edward
Remembering that preoperative planning, surgical indications, and fracture reduction are paramount for this procedure, presented here is our technique for performing percutaneous sacroiliac screws, both transiliac-transsacral and sacral style. A combination of video, still pictures, and fluoroscopy images will guide the viewer through the process we routinely use highlighting specific details. Patient positioning and intraoperative fluoroscopy imaging are critical to a successful procedure. Although inlet and outlet films remain important, we find the procedure best started on the lateral sacral view to reduce the need for start site, trajectory, and imaging position changes during the case. A cannulated pig sticker (drill guide) used with long drill tip guide wires provide improved manual control to both finding a good start site and directing the trajectory. For patient safety, sacral anatomy and safe zones are discussed as well. Using these technical points will help make this a successful procedure. PMID:27441927
Mechanotransduction in intervertebral discs
Tsai, Tsung-Ting; Cheng, Chao-Min; Chen, Chien-Fu; Lai, Po-Liang
Mechanotransduction plays a critical role in intracellular functioning—it allows cells to translate external physical forces into internal biochemical activities, thereby affecting processes ranging from proliferation and apoptosis to gene expression and protein synthesis in a complex web of interactions and reactions. Accordingly, aberrant mechanotransduction can either lead to, or be a result of, a variety of diseases or degenerative states. In this review, we provide an overview of mechanotransduction in the context of intervertebral discs, with a focus on the latest methods of investigating mechanotransduction and the most recent findings regarding the means and effects of mechanotransduction in healthy and degenerative discs. We also provide some discussion of potential directions for future research and treatments. PMID:25267492
Biomechanics of Disc Degeneration
Palepu, V.; Kodigudla, M.; Goel, V. K.
Disc degeneration and associated disorders are among the most debated topics in the orthopedic literature over the past few decades. These may be attributed to interrelated mechanical, biochemical, and environmental factors. The treatment options vary from conservative approaches to surgery, depending on the severity of degeneration and response to conservative therapies. Spinal fusion is considered to be the "gold standard" in surgical methods till date. However, the association of adjacent level degeneration has led to the evolution of motion preservation technologies like spinal arthroplasty and posterior dynamic stabilization systems. These new technologies are aimed to address pain and preserve motion while maintaining a proper load sharing among various spinal elements. This paper provides an elaborative biomechanical review of the technologies aimed to address the disc degeneration and reiterates the point that biomechanical efficacy followed by long-term clinical success will allow these nonfusion technologies as alternatives to fusion, at least in certain patient population. PMID:22745914
Schnake, K J; Hoffmann, C-H; Kandziora, F
The cervical disc herniation is characterized by prolapsed nucleus pulposus material through the annulus into the spinal canal. The local mechanical or chemical irritation of neural structures typically leads to symptoms of radiculopathy, cervicocephalgia or myelopathy. Pronounced sensorimotor deficits or intractable pain constitute surgical treatment. In all other cases conservative treatment is indicated, including pain medication, active and passive physiotherapy, and local injections, respectively. Anterior cervical discectomy and interbody fusion (ACDF) is still the surgical treatment of choice. Predominantly, cages with or without plates are in use to obtain solid fusion. The implantation of a total disc replacement is a viable alternative, if no contraindications exist. Other surgical techniques may be performed in proper selected cases. The overall clinical and radiological results of both surgical and conservative treatment are good. PMID:23296562
Vital, J-M; Boissière, L
Total disc replacement (TDR) (partial disc replacement will not be described) has been used in the lumbar spine since the 1980s, and more recently in the cervical spine. Although the biomechanical concepts are the same and both are inserted through an anterior approach, lumbar TDR is conventionally indicated for chronic low back pain, whereas cervical TDR is used for soft discal hernia resulting in cervicobrachial neuralgia. The insertion technique must be rigorous, with precise centering in the disc space, taking account of vascular anatomy, which is more complex in the lumbar region, particularly proximally to L5-S1. All of the numerous studies, including prospective randomized comparative trials, have demonstrated non-inferiority to fusion, or even short-term superiority regarding speed of improvement. The main implant-related complication is bridging heterotopic ossification with resulting loss of range of motion and increased rates of adjacent segment degeneration, although with an incidence lower than after arthrodesis. A sufficiently long follow-up, which has not yet been reached, will be necessary to establish definitively an advantage for TDR, particularly in the cervical spine. PMID:24412045
Counter-rotating accretion discs
NASA Astrophysics Data System (ADS)
Dyda, S.; Lovelace, R. V. E.; Ustyugova, G. V.; Romanova, M. M.; Koldoba, A. V.
Counter-rotating discs can arise from the accretion of a counter-rotating gas cloud on to the surface of an existing corotating disc or from the counter-rotating gas moving radially inwards to the outer edge of an existing disc. At the interface, the two components mix to produce gas or plasma with zero net angular momentum which tends to free-fall towards the disc centre. We discuss high-resolution axisymmetric hydrodynamic simulations of viscous counter-rotating discs for the cases where the two components are vertically separated and radially separated. The viscosity is described by an isotropic α-viscosity including all terms in the viscous stress tensor. For the vertically separated components, a shear layer forms between them and the middle part of this layer free-falls to the disc centre. The accretion rates are increased by factors of ˜102-104 over that for a conventional disc rotating in one direction with the same viscosity. The vertical width of the shear layer and the accretion rate are strongly dependent on the viscosity and the mass fraction of the counter-rotating gas. In the case of radially separated components where the inner disc corotates and the outer disc rotates in the opposite direction, a gap between the two components opens and closes quasi-periodically. The accretion rates are ≳25 times larger than those for a disc rotating in one direction with the same viscosity.
Have protoplanetary discs formed planets?
NASA Astrophysics Data System (ADS)
Greaves, J. S.; Rice, W. K. M.
It has recently been noted that many discs around T Tauri stars appear to comprise only a few Jupiter masses of gas and dust. Using millimetre surveys of discs within six local star formation regions, we confirm this result, and find that only a few per cent of young stars have enough circumstellar material to build gas giant planets, in standard core accretion models. Since the frequency of observed exoplanets is greater than this, there is a `missing-mass' problem. As alternatives to simply adjusting the conversion of dust flux to disc mass, we investigate three other classes of solution. Migration of planets could hypothetically sweep up the disc mass reservoir more efficiently, but trends in multiplanet systems do not support such a model, and theoretical models suggest that the gas accretion time-scale is too short for migration to sweep the disc. Enhanced inner-disc mass reservoirs are possible, agreeing with predictions of disc evolution through self-gravity, but not adding to millimetre dust flux as the inner disc is optically thick. Finally, the incidence of massive discs is shown to be higher at the protostellar stages, Classes 0 and I, where discs substantial enough to form planets via core accretion are abundant enough to match the frequency of exoplanets. Gravitational instability may also operate in the Class 0 epoch, where half the objects have potentially unstable discs of >~30 per cent of the stellar mass. However, recent calculations indicate that forming gas giants inside 50 au by instability is unlikely, even in such massive discs. Overall, the results presented suggest that the canonically `protoplanetary' discs of Class II T Tauri stars have globally low masses in dust observable at millimetre wavelengths, and conversion to larger bodies (anywhere from small rocks up to planetary cores) must already have occurred.
Intelligent Video Disc as a Major Component of Individualized Instruction.
ERIC Educational Resources Information Center
Ingalls, Richard E.
Due to the importance of visual stimuli for learning, the videodisc is expected to have a major impact on education. When combined with the computer, it will greatly expand the capabilities of computer assisted instruction. There are two major types of videodisc equipment: the optical type with a laser beam to read the information from the disc,…
Disc edge veins of Kraupa associated with optic disc drusen
Díaz, Andrea; Almela, Miguel Angel
Objective: Disc edge veins of Kraupa are a rare anomaly of the retinal venous system in which the main trunk of the retinal vein disappeared into the margin of the optic disc instead of its centre. Methods: A 40-year-old woman was detected to have an anomaly in her left optic disc in a routine eye examination. The eyes had an anomaly of the retinal venous system in which all branches of the retinal vein joined in a common trunk that entered the disc margin inferonasally. The central retinal artery issued from the centre of the disc separately of the venous system. B-scan ultrasonografhy revealed the presence of hyperechoic imaging at the optic nerve head in both eyes. Results: We describe the association of disc edge veins of Kraupa with optic disc drusen. Conclusion: Vascular complications of optic disc drusen hav been described. We don't know the implication of disc edge veins in the pathogenesis of these complications.
Enclosed rotary disc air pulser
Olson, A. L.; Batcheller, Tom A.; Rindfleisch, J. A.; Morgan, John M.
An enclosed rotary disc air pulser for use with a solvent extraction pulse olumn includes a housing having inlet, exhaust and pulse leg ports, a shaft mounted in the housing and adapted for axial rotation therein, first and second disc members secured to the shaft within the housing in spaced relation to each other to define a chamber therebetween, the chamber being in communication with the pulse leg port, the first disc member located adjacent the inlet port, the second disc member being located adjacent the exhaust port, each disc member having a milled out portion, the disc members positioned on the shaft so that as the shaft rotates, the milled out portions permit alternative cyclical communication between the inlet port and the chamber and the exhaust port and the chamber.
NASA Astrophysics Data System (ADS)
Kasparova, A.; Katkov, I.; Chilingarian, I.; Silchenko, O.; Moiseev, A.; Borisov, S.
Although thick stellar discs are detected in nearly all edge-on disc galaxies, their formation scenarios still remain a matter of debate. Due to observational difficulties, there is a lack of information about their stellar populations. Using the Russian 6-m telescope BTA we collected deep spectra of thick discs in three edge-on early-type disc galaxies located in different environments: NGC4111 in a dense group, NGC4710 in the Virgo cluster, and NGC5422 in a sparse group. We see intermediate age (4 ‑ 5 Gyr) metal rich ([Fe/H] ~ ‑0.2 ‑ 0.0 dex) stellar populations in NGC4111 and NGC4710. On the other hand, NGC5422 does not harbour young stars, its only disc is thick and old (10 Gyr) and its α-element abundance suggests a long formation epoch implying its formation at high redshift. Our results prove the diversity of thick disc formation scenarios.
Laser biostimulation in pediatrics
NASA Astrophysics Data System (ADS)
Utz, Irina A.; Lagutina, L. E.; Tuchin, Valery V.
In the present paper the method and apparatus for percutaneous laser irradiation of blood (PLIB) in vessels (veins) are described. Results of clinical investigations of biostimulating effects under PLIB by red laser light (633 nm) in Cubiti and Saphena Magna veins are presented.
Percutaneous coronary angioscopy with a new steerable microangioscope: experimental and early clinical results
NASA Astrophysics Data System (ADS)
Ramee, Stephen R.; White, Christopher J.; Mesa, Juan E.; Murgo, Joseph P.; Doyle, Andrew T.; McQueen, Colleen L.
We have developed a new, steerable microangioscope for performing percutaneous coronary angioscopy. The angioscopic catheter is made of polyethylene, contains a distal balloon for occlusion of blood flow during imaging, fits through an 8 Fr percutaneous coronary angioplasty (PTCA) guiding catheter and is steerable by means of a guidewire. Initial feasibility was demonstrated in animal studies involving both peripheral and coronary arteries. Angioscopic findings in normal vessels included normal endothelial surface, collateral blood flow, and side branches. Angioscopy was also performed after balloon denudation of the arteries, laser- assisted balloon angioplasty, and stent implantation. In early human clinical trials we have performed percutaneous angioscopy in six patients undergoing percutaneous coronary angioplasty without complications. Findings in these patients include atherosclerotic plaque, thrombus, and dissection. This new device has great potential for use in the research, diagnosis, and treatment of coronary atherosclerosis.
Delayed Nephropleural Fistula After Percutaneous Nephrolithotomy.
Kaler, Kamaljot S; Cwikla, Daniel; Clayman, Ralph V
Pleural effusions due to pleural injury following supracostal percutaneous nephrolithotomy (PCNL) occur in upwards of 15% of patients; however, these effusions are invariably diagnosed immediately postoperative or during the hospital stay. Herein, we report our initial experience with a delayed nephropleural fistula. A 52-year-old female underwent an uneventful supracostal right PCNL staghorn stone procedure and was discharged on postoperative day 1. She presented to the emergency department 8 days after her original procedure and one day after ureteral stent removal in the office, with right pleural effusion, concomitant contralateral renal colic secondary to migration of a left pelvic stone into her left proximal ureter, and acute renal failure/oliguria. She was treated with right chest tube drainage, bilateral nephrostomy tube placement, and subsequent left holmium laser ureterolithotripsy. PMID:27579431
Percutaneous foam sclerotherapy for venous leg ulcers.
Bush, R; Bush, P
The technique of foam sclerotherapy directed at the distal most vessels, draining the ulcer bed was first described in 2010, with excellent penetration into the underlying venous network possible with this technique. Thirty-five patients have now been treated with this technique as the initial treatment at Midwest Vein Laser, USA. There have been no complications with this technique and rapid healing occurred within 4-8 weeks after the initial treatment in 90% of the patients, and all ulcers were healed at 4 months. Here we present the representative case of a 67-year-old man treated with a modified technique that used a percutaneous approach via reticular or spider veins at the margin of the ulcer bed. PMID:24142137
Delayed Nephropleural Fistula After Percutaneous Nephrolithotomy
Kaler, Kamaljot S.; Cwikla, Daniel
Abstract Pleural effusions due to pleural injury following supracostal percutaneous nephrolithotomy (PCNL) occur in upwards of 15% of patients; however, these effusions are invariably diagnosed immediately postoperative or during the hospital stay. Herein, we report our initial experience with a delayed nephropleural fistula. A 52-year-old female underwent an uneventful supracostal right PCNL staghorn stone procedure and was discharged on postoperative day 1. She presented to the emergency department 8 days after her original procedure and one day after ureteral stent removal in the office, with right pleural effusion, concomitant contralateral renal colic secondary to migration of a left pelvic stone into her left proximal ureter, and acute renal failure/oliguria. She was treated with right chest tube drainage, bilateral nephrostomy tube placement, and subsequent left holmium laser ureterolithotripsy. PMID:27579431
Numbered nasal discs for waterfowl
Bartonek, J.C.; Dane, C.W.
Numbered nasal discs were successfully used in studies requiring large numbers of individually marked waterfowl. The procedure for constructing these discs is outlined. Blue-winged teal (Anas discors) with 5/8-inch discs, and canvasback (Aythya valisineria) and redhead (A. americana) with 3/4-inch discs can be individually identified up to 50 and 80 yards, respectively, with a gunstock-mounted, 20-power spotting scope. The particular value of these markers is their durability, the number of combinations possible, and the apparent absence of behavioral or mortality influence among such species as the blue-winged teal.
Development of fluorescent multilayer disc structure
NASA Astrophysics Data System (ADS)
Beliak, Ievgen; Butenko, Larisa
The fluorescent multilayer disc (FMD) consists of a substrate and the sandwich-structure of information and intermediate layers. While all the structure of the disc is transparent and homogeneous the parasitic signal will be caused mostly by photoluminescence (PL) and absorption of pits areas where laser light is unfocused. At large number of layers (10 or more) the noise level will get significant value, so it was suggested to derive readout signal as a variable one. Also it was proposed to record information only by the lands, to decrease the absorbance level and thus uncontrolled changing of the noise level. Furthermore in the FMD information layer there are inner and outside peripheral areas which hold a stable level of parasitic signal during readout from the edges of the disc. While the PL readout signal is spatially isotropic the optical head of the FMD drive receives just a part of the probing beam energy. PL quantum yield, absorption factor, receiver systems exposure loss coefficients are other reasons of the low PL signal. Thus the problem of the low SNR in this case is a major one and the only way of its solving is synthesis of the dye with a high PL quantum yield. The PL relaxation time on the other hand is a main feature of the data reading rate and therefore selection of the appropriate recording material will allow to bring this parameter in accordance to parameters of modern optical discs. To achieve this goal the composite organic pyrazoline dyes where synthesized and investigated as effective medium with a PL quantum yield up to 60-70%, relaxation time less than 100 ns, PL wide spectrum and opportunity of two-photon absorption. These parameters were further improved by a method based on the performance of organic dye molecules in the zeolite matrix.
Preparation of ormetoprim sulfadimethoxine medicated discs for disc diffusion assay
Technology Transfer Automated Retrieval System (TEKTRAN)
Romet (a blend of ormetoprim and sulfadimethoxine) is a typeA medicated article for the manufacture of medicated feed in the catfish industry. Recently, the commercial manufacture of ormetoprim–sulfadimethoxine susceptibility discs was discontinued. Ormetoprim–sulfadimethoxine discs were prepared at...
Buried bumper syndrome: A complication of percutaneous endoscopic gastrostomy
Cyrany, Jiri; Rejchrt, Stanislav; Kopacova, Marcela; Bures, Jan
Percutaneous endoscopic gastrostomy (PEG) is a widely used method of nutrition delivery for patients with long-term insufficiency of oral intake. The PEG complication rate varies from 0.4% to 22.5% of cases, with minor complications being three times more frequent. Buried bumper syndrome (BBS) is a severe complication of this method, in which the internal fixation device migrates alongside the tract of the stoma outside the stomach. Excessive compression of tissue between the external and internal fixation device of the gastrostomy tube is considered the main etiological factor leading to BBS. Incidence of BBS is estimated at around 1% (0.3%-2.4%). Inability to insert, loss of patency and leakage around the PEG tube are considered to be a typical symptomatic triad. Gastroscopy is indicated in all cases in which BBS is suspected. The depth of disc migration in relation to the lamina muscularis propria of the stomach is critical for further therapy and can be estimated by endoscopic or transabdominal ultrasound. BBS can be complicated by gastrointestinal bleeding, perforation, peritonitis, intra-abdominal and abdominal wall abscesses, or phlegmon, and these complications can lead to fatal outcomes. The most important preventive measure is adequate positioning of the external bolster. A conservative approach should be applied only in patients with high operative risk and dismal prognosis. Choice of the method of release is based on the type of the PEG set and depth of disc migration. A disc retained inside the stomach and completely covered by the overgrowing tissue can be released using some type of endoscopic dissection technique (needle knife, argon plasma coagulation, or papillotome through the cannula). Proper patient selection and dissection of the overgrowing tissue are the major determinants for successful endoscopic therapy. A disc localized out of the stomach (lamina muscularis propria) should be treated by a surgeon. PMID:26811611
Percutaneous Ablation of Adrenal Tumors
Venkatesan, Aradhana M.; Locklin, Julia; Dupuy, Damian E.; Wood, Bradford J.
Adrenal tumors comprise a broad spectrum of benign and malignant neoplasms, and include functional adrenal adenomas, pheochromocytomas, primary adrenocortical carcinoma and adrenal metastases. Percutaneous ablative approaches that have been described and used in the treatment of adrenal tumors include percutaneous radiofrequency ablation (RFA), cryoablation, microwave ablation and chemical ablation. Local tumor ablation in the adrenal gland presents unique challenges, secondary to the adrenal gland's unique anatomic and physiologic features. The results of clinical series employing percutaneous ablative techniques in the treatment of adrenal tumors are reviewed in this article. Clinical and technical considerations unique to ablation in the adrenal gland are presented, including approaches commonly used in our practices, and risks and potential complications are discussed. PMID:20540918
Percutaneous Hindfoot and Midfoot Fusion.
Bauer, Thomas
Hindfoot and midfoot fusions can be performed with percutaneous techniques. Preliminary results of these procedures are encouraging because they provide similar results than those obtained with open techniques with less morbidity and quick recovery. The best indications are probably fusions for mild-to-moderate reducible hindfoot and midfoot deformities in fragile patients with general or local bad conditions. The main limit is linked to the surgeon's experience in percutaneous foot surgery because a learning curve with the specific tools is necessary before doing these procedures. PMID:27524709
Interactive Laser Video Disc. Health Occupations Education.
ERIC Educational Resources Information Center
Beam, Glennie; Wright, Patsy
This module is intended to assist secondary school instructors in selecting and evaluating courseware related to the health occupations education curriculum. The main section contains descriptions of 20 pieces of courseware. Each entry includes the following information: title, description, audience, vendor, price, and recommendation. A glossary…
Write-Once Laser Disc Technology.
ERIC Educational Resources Information Center
Slonim, Jacob; And Others
This article presents a brief history of the videodisc and describes three major current manifestations of this storage medium--read-only, write-once, erasable. The current status of write-once technology, major corporations involved in the field, potential uses for various types of storage media, and software and market trends are highlighted.…
Cervical Total Disc Arthroplasty
Basho, Rahul; Hood, Kenneth A.
Symptomatic adjacent segment degeneration of the cervical spine remains problematic for patients and surgeons alike. Despite advances in surgical techniques and instrumentation, the solution remains elusive. Spurred by the success of total joint arthroplasty in hips and knees, surgeons and industry have turned to motion preservation devices in the cervical spine. By preserving motion at the diseased level, the hope is that adjacent segment degeneration can be prevented. Multiple cervical disc arthroplasty devices have come onto the market and completed Food and Drug Administration Investigational Device Exemption trials. Though some of the early results demonstrate equivalency of arthroplasty to fusion, compelling evidence of benefits in terms of symptomatic adjacent segment degeneration are lacking. In addition, non-industry-sponsored studies indicate that these devices are equivalent to fusion in terms of adjacent segment degeneration. Longer-term studies will eventually provide the definitive answer. PMID:24353955
Wheatley, Seth J.
This invention relates to an improvement in a conventional double-disc gate valve having a vertically movable gate assembly including a wedge, spreaders slidably engaged therewtih, a valve disc carried by the spreaders. When the gate assembly is lowered to a selected point in the valve casing, the valve discs are moved transversely outward to close inlet and outlet ports in the casing. The valve includes hold-down means for guiding the disc-and-spreader assemblies as they are moved transversely outward and inward. If such valves are operated at relatively high differential pressures, they sometimes jam during opening. Such jamming has been a problem for many years in gate valves used in gaseous diffusion plants for the separtion of uranium isotopes. The invention is based on the finding that the above-mentioned jamming results when the outlet disc tilts about its horizontal axis in a certain way during opening of the valve. In accordance with the invention, tilting of the outlet disc is maintained at a tolerable value by providing the disc with a rigid downwardly extending member and by providing the casing with a stop for limiting inward arcuate movement of the member to a preselected value during opening of the valve.
Discs in misaligned binary systems
NASA Astrophysics Data System (ADS)
Rawiraswattana, Krisada; Hubber, David A.; Goodwin, Simon P.
We perform SPH simulations to study precession and changes in alignment between the circumprimary disc and the binary orbit in misaligned binary systems. We find that the precession process can be described by the rigid-disc approximation, where the disc is considered as a rigid body interacting with the binary companion only gravitationally. Precession also causes change in alignment between the rotational axis of the disc and the spin axis of the primary star. This type of alignment is of great important for explaining the origin of spin-orbit misaligned planetary systems. However, we find that the rigid-disc approximation fails to describe changes in alignment between the disc and the binary orbit. This is because the alignment process is a consequence of interactions that involve the fluidity of the disc, such as the tidal interaction and the encounter interaction. Furthermore, simulation results show that there are not only alignment processes, which bring the components towards alignment, but also anti-alignment processes, which tend to misalign the components. The alignment process dominates in systems with misalignment angle near 90°, while the anti-alignment process dominates in systems with the misalignment angle near 0° or 180°. This means that highly misaligned systems will become more aligned but slightly misaligned systems will become more misaligned.
The value of percutaneous cholangiography
Evison, Gordon; McNulty, Myles; Thomson, Colin
Percutaneous cholangiograms performed on fifty patients in a district general hospital have been reviewed, and the advantages and limitations of the examination are described. The investigation is considered to have sufficient diagnostic value to warrant its inclusion in the diagnostic armamentarium of every general radiological department. ImagesFig. 1Fig. 2Fig. 3Fig. 4 PMID:4788917
Complications of percutaneous vertebroplasty
Saracen, Agnieszka; Kotwica, Zbigniew
Abstract Percutaneous vertebroplasty (PVP) is a minimally invasive procedure widely used for the treatment of pain due to vertebral fractures of different origins—osteoporotic, traumatic, or neoplastic. PVP is minimally invasive, but the complications are not rare; however, they are in most cases not significant clinically. The most frequent is cement leakage, which can occur onto veins, paravertebral soft tissue, into the intervertebral disk, or to the spinal canal, affecting foraminal area or epidural space. We analyzed results of treatment and complications of vertebroplasty performed with the use of polimethylomethylacrylate cement (PMMA) on 1100 vertebrae, with a special regard to the severity of complication and eventual clinical manifestation. One thousand one hundred PVP were analyzed, performed in 616 patients. There were 468 (76%) women and 148 men (24%), 24 to 94-year old, mean age 68 years. From 1100 procedures, 794 treated osteporotic and 137 fractures due to malignant disease, 69 PVP were made in traumatic fractures. One hundred patients had painful vertebral hemangiomas. Seven hundred twenty-six (66%) lesions were in thoracic, and 374 (34%) in lumbar area. Results of treatment were assessed using 10 cm Visual Analogue Scale (VAS) 12 hours after surgery, 7 days, 30 days, and then each 6 months, up to 3 years. Before surgery all patients had significant pain 7 to 10 in VAS scale, mean 8.9 cm. Twelve hours after surgery 602 (97.7%) reported significant relief of pain, with mean VAS of 2,3 cm. Local complications occurred in 50% of osteoporotic, 34% of neoplastic, 16% of traumatic fractures, and 2% of vertebral hemangiomas. The most common was PMMA leakage into surrounding tissues—20%; paravertebral vein embolism—13%; intradiscal leakage—8%; and PMMA leakage into the spinal canal—0.8%. Results of treatment did not differ between patients with and without any complications. From 104 patients who had chest X-ray or CT study performed
Medical Information on Optical Disc*
Schipma, Peter B.; Cichocki, Edward M.; Ziemer, Susan M.
Optical discs may permit a revolutionary change in the distribution and use of medical information. A single compact disc, similar in size to that used for digital audio recording, can contain over 500 million characters of information that is accessible by a Personal Computer. These discs can be manufactured at a cost lower than that of print on paper, at reasonable volumes. Software can provide the health care professional with nearly instantaneous access to the information. Thus, for the first time, the opportunity exists to have large local medical information collections. This paper describes an application of this technology in the field of Oncology.
A fully automated immunoassay from whole blood on a disc.
Lee, Beom Seok; Lee, Jung-Nam; Park, Jong-Myeon; Lee, Jeong-Gun; Kim, Suhyeon; Cho, Yoon-Kyoung; Ko, Christopher
A portable, disc-based, and fully automated enzyme-linked immuno-sorbent assay (ELISA) system is developed to test infectious diseases from whole blood. The innovative laser irradiated ferrowax microvalves and centrifugal microfluidics were utilized for the full integration of microbead-based suspension ELISA assays on a disc starting from whole blood. The concentrations of the antigen and the antibody of Hepatitis B virus (HBV), HBsAg and Anti-HBs respectively, were measured using the lab-on-a-disc (LOD). All the necessary reagents are preloaded on the disc and the total process of the plasma separation, incubation with target specific antigen or antibody coated microbeads, multiple steps of washing, enzyme reaction with substrates, and the absorbance detection could be finished within 30 minutes. Compared to the conventional ELISA, the operation time was dramatically reduced from over 2 hours to less than 30 minutes while the limit of detection was kept similar; e.g. the limit of detection of Anti-HBs tests were 8.6 mIU mL(-1) and 10 mIU mL(-1) for the disc-based and the conventional ELISA respectively. PMID:19458861
Berg, Svante
Low back pain consumes a large part of the community's resources dedicated to health care and sick leave. Back disorders also negatively affect the individual leading to pain suffering, decreased quality-of-life and disability. Chronic low back pain (CLBP) due to degenerative disc disease (DDD) is today often treated with fusion when conservative treatment has failed and symptoms are severe. This treatment is as successful as arthroplasty is for hip arthritis in restoring the patient's quality of life and reducing disability. Even so, there are some problems with this treatment, one of these being recurrent CLBP from an adjacent segment (ASD) after primarily successful surgery. This has led to the development of alternative surgical treatments and devices that maintain or restore mobility, in order to reduce the risk for ASD. Of these new devices, the most frequently used are the disc prostheses used in Total Disc Replacement (TDR). This thesis is based on four studies comparing total disc replacement with posterior fusion. The studies are all based on a material of 152 patients with DDD in one or two segments, aged 20-55 years that were randomly treated with either posterior fusion or TDR. The first study concerned clinical outcome and complications. Follow-up was 100% at both one and two years. It revealed that both treatment groups had a clear benefit from treatment and that patients with TDR were better in almost all outcome scores at one-year follow-up. Fusion patients continued to improve during the second year. At two-year follow-up there was a remaining difference in favour of TDR for back pain. 73% in the TDR group and 63% in the fusion group were much better or totally pain-free (n.s.), while twice as many patients in the TDR group were totally pain free (30%) compared to the fusion group (15%). Time of surgery and total time in hospital were shorter in the TDR group. There was no difference in complications and reoperations, except that seventeen of the
Decellularized allogeneic intervertebral disc: natural biomaterials for regenerating disc degeneration
Hu, Zhijun; Chen, Kai; Shan, Zhi; Chen, Shuai; Wang, Jiying; Mo, Jian; Ma, Jianjun; Xu, Wenbing; Qin, An; Fan, Shunwu
Intervertebral disc degeneration is associated with back pain and disc herniation. This study established a modified protocol for intervertebral disc (IVD) decellularization and prepared its extracellular matrix (ECM). By culturing mesenchymal stem cells (MSCs)(3, 7, 14 and 21 days) and human degenerative IVD cells (7 days) in the ECM, implanting it subcutaneously in rabbit and injecting ECM microparticles into degenerative disc, the biological safety and efficacy of decellularized IVD was evaluated both in vitro and in vivo. Here, we demonstrated that cellular components can be removed completely after decellularization and maximally retain the structure and biomechanics of native IVD. We revealed that allogeneic ECM did not evoke any apparent inflammatory reaction in vivo and no cytotoxicity was found in vitro. Moreover, IVD ECM can induce differentiation of MSCs into IVD-like cells in vitro. Furthermore, allogeneic ECM microparticles are effective on the treatment of rabbit disc degeneration in vivo. In conclusion, our study developed an optimized method for IVD decellularization and we proved decellularized IVD is safe and effective for the treatment of degenerated disc diseases. PMID:26933821
Enlivening Physics, a Local Video Disc Project.
ERIC Educational Resources Information Center
McInerney, M.
Describes how to make and use an inexpensive video disc of physics demonstrations. Discusses the background, production of the disc, subject of the disc including angular momentum, "monkey and the hunter" experiment, Doppler shift, pressure of a constant volume of gas thermometer, and wave effects, and using the disc in classroom. (YP)
Disc Golf: Teaching a Lifetime Activity
ERIC Educational Resources Information Center
Eastham, Susan L.
Disc golf is a lifetime activity that can be enjoyed by students of varying skill levels and abilities. Disc golf follows the principles of ball golf but is generally easier for students to play and enjoy success. The object of disc golf is similar to ball golf and involves throwing a disc from the teeing area to the target in as few throws as…
Tissue engineering: A live disc
NASA Astrophysics Data System (ADS)
Hukins, David W. L.
A material-cell hybrid device that mimics the anatomic shape of the intervertebral disc has been made and successfully implanted into mice to show that tissue engineering may, in the future, benefit sufferers from back pain.
Nelson, Joseph T.; Jones, Richard E.; Runstrom, Michael; Hardy, Jolene
Background Disc golf is a sport played much like traditional golf, but rather than using a ball and club, players throw flying discs with various throwing motions. It has been played by an estimated 8 to 12 million people in the United States. Like all sports, injuries sustained while playing disc golf are not uncommon. Although formalized in the 1970s, it has grown at a rapid pace; however, disc golf–related injuries have yet to be described in the medical literature. Purpose To describe the most common injuries incurred by disc golf players while comparing the different types of throwing styles. Study Design Descriptive epidemiology study. Methods The data in this study were collected from 883 disc golf players who responded to an online survey collected over a 1-month period. Respondents answered 49 questions related to demographics, experience, style of play, and injury details. Using a chi-square analysis, common injuries sustained in players using backhand and forehand throwing styles were compared. Results More than 81% of respondents stated that they had sustained an injury playing disc golf, including injuries to the elbow (n = 325), shoulder (n = 305), back (n = 218), and knee (n = 199). The injuries were most commonly described as a muscle strain (n = 241), sprain (n = 162), and tendinitis (n = 145). The type of throw primarily used by players varied, with 86.2% using backhand, 12.7% using forehand, and 1.1% using an overhead throw. Players using a forehand throw were more likely to sustain an elbow injury (P = .014). Many players (n = 115) stated they had undergone surgery due to a disc golf–related injury, with the most common surgeries including meniscal, shoulder, spine, and foot/ankle surgeries. Conclusion The majority of surveyed disc golfers sustained at least 1 injury while playing disc golf, with many requiring surgery. The types of injuries sustained by players varied by the types of throw primarily used. As the sport of disc golf continues
Disc piezoelectric ceramic transformers.
Erhart, Jirií; Půlpán, Petr; Doleček, Roman; Psota, Pavel; Lédl, Vít
In this contribution, we present our study on disc-shaped and homogeneously poled piezoelectric ceramic transformers working in planar-extensional vibration modes. Transformers are designed with electrodes divided into wedge, axisymmetrical ring-dot, moonie, smile, or yin-yang segments. Transformation ratio, efficiency, and input and output impedances were measured for low-power signals. Transformer efficiency and transformation ratio were measured as a function of frequency and impedance load in the secondary circuit. Optimum impedance for the maximum efficiency has been found. Maximum efficiency and no-load transformation ratio can reach almost 100% and 52 for the fundamental resonance of ring-dot transformers and 98% and 67 for the second resonance of 2-segment wedge transformers. Maximum efficiency was reached at optimum impedance, which is in the range from 500 Ω to 10 kΩ, depending on the electrode pattern and size. Fundamental vibration mode and its overtones were further studied using frequency-modulated digital holographic interferometry and by the finite element method. Complementary information has been obtained by the infrared camera visualization of surface temperature profiles at higher driving power. PMID:25004532
Combined Endoscopic and Percutaneous Retrieval of a Retained 4-Wire Ureteral Stone Basket
Kaplan, Adam G.; Preminger, Glenn M.
Abstract Complex endourologic procedures may require the use of a combined ureteroscopic and percutaneous approach. Endoscopic removal of a retained 4-wire ureteral stone basket is particularly complex, as broken tines can potentially injure the ureter if the basket is removed in a retrograde manner. The patient in this case presented with a ureteral stone basket embedded within the urothelium of the upper pole of the kidney. Holmium laser incision of the overlying urothelium allowed retrieval of the basket, although the tines were broken. Endoscopically guided percutaneous access to the kidney was obtained to allow for direct passage of the retained basket out of a nephrostomy sheath, thereby protecting the kidney.
MRI Evaluation of Lumbar Disc Degenerative Disease
Patel, Rupal; Mehta, Chetan; Patel, Narrotam
Introduction: Lower back pain secondary to degenerative disc disease is a condition that affects young to middle-aged persons with peak incidence at approximately 40 y. MRI is the standard imaging modality for detecting disc pathology due to its advantage of lack of radiation, multiplanar imaging capability, excellent spinal soft-tissue contrast and precise localization of intervertebral discs changes. Aims and Objective: To evaluate the characterization, extent, and changes associated with the degenerative lumbar disc disease by Magnetic Resonance Imaging. Study Design: Cross-sectional and observational study. Materials and Methods: A total 109 patients of the lumbar disc degeneration with age group between 17 to 80 y were diagnosed & studied on 1.5 Tesla Magnetic Resonance Imaging machine. MRI findings like lumbar lordosis, Schmorl's nodes, decreased disc height, disc annular tear, disc herniation, disc bulge, disc protrusion and disc extrusion were observed. Narrowing of the spinal canal, lateral recess and neural foramen with compression of nerve roots observed. Ligamentum flavum thickening and facetal arthropathy was observed. Result: Males were more commonly affected in Degenerative Spinal Disease & most of the patients show loss of lumbar lordosis. Decreased disc height was common at L5-S1 level. More than one disc involvement was seen per person. L4 – L5 disc was the most commonly involved. Annular disc tear, disc herniation, disc extrusion, narrowing of spinal canal, narrowing of lateral recess, compression of neural foramen, ligamentum flavum thickening and facetal arthropathy was common at the L4 –L5 disc level. Disc buldge was common at L3 – L4 & L4 – L5 disc level. Posterior osteophytes are common at L3 - L4 & L5 –S1 disc level. L1- L2 disc involvement and spondylolisthesis are less common. Conclusion: Lumbar disc degeneration is the most common cause of low back pain. Plain radiograph can be helpful in visualizing gross anatomic changes in
Percutaneous absorption in preterm infants.
West, D P; Halket, J M; Harvey, D R; Hadgraft, J; Solomon, L M; Harper, J I
The skin of preterm infants varies considerably in its level of maturity. To understand skin absorption in premature infants better, we report a technique for the assessment of percutaneous absorption at various gestational and postnatal ages using stable, isotope-labeled (13C6) benzoic acid. Our results indicate that in the preterm infant, this method detects enhanced skin absorption in the first postnatal days, which declines over three weeks to that expected of a full-term infant. This approach also indicates an inverse relationship between gestational age and skin absorption, as well as postnatal age and skin absorption. The reported technique is a safe and noninvasive method using a model skin penetrant for the study of percutaneous absorption in preterm infants from which basic data may be derived to add to our understanding of skin barrier function. PMID:3422856
New instrumentation in percutaneous nephrolithotomy
Pugh, Joseph W.; Canales, Benjamin K.
Percutaneous nephrolithotomy (PCNL) is the procedure of choice for removing large, complex, and/or multiple renal calculi. Since its first description in 1976, PCNL techniques and equipment have evolved to maximize procedural efficacy, safety, and reproducibility. We reviewed current literature from January 2004 to November 2009 using Medline search regarding PCNL instrumentation and technology. Additional equipment discovered during the review process without published Medline evidence was summarized from manufacturer brochures and data. Included in this review are summaries of intracorporeal lithotriptors and accessory equipment, stone manipulation devices, PCNL tract sealants, and a digital rigid nephroscope. The evolution of these devices from their predecessors has increased the instrumentation options for the treating urologist and may represent more effective technology for the percutaneous treatment of large renal stones. PMID:21116361
Percutaneous renal cryoablation: current status.
Mazaris, Evangelos M; Varkarakis, Ioannis M; Solomon, Stephen B
Over the last 13 years, renal cryoablation has emerged as a promising technique for the treatment of solid renal tumors. The improvement in imaging modalities such as ultrasound, computed tomography and MRI, as well as the introduction of thinner probes, has led to the spread of the minimally invasive percutaneous approach. We review the historical background of percutaneous renal cryoablation (PRC), present its basic principles, mention the contemporary clinical data and outcomes of this technique and suggest future directions for its wider application in renal tumors. Early results have demonstrated that it may offer an alternative for the treatment of small renal masses with the advantages of minimal complications, spared renal function, decreased overall costs and equivalent oncologic efficacy. Long-term results are required in order to apply this minimally invasive technique to a broader spectrum of patients. PMID:18407738
Percutaneous penetration--methodological considerations.
Holmgaard, Rikke; Benfeldt, Eva; Nielsen, Jesper B
Studies on percutaneous penetration are needed to assess the hazards after unintended occupational skin exposures to industrial products as well as the efficacy after intended consumer exposure to topically applied medicinal or cosmetic products. During recent decades, a number of methods have been developed to replace methods involving experimental animals. The results obtained from these methods are decided not only by the chemical or product tested, but to a significant degree also by the experimental set-up and decisions made by the investigator during the planning phase. The present MiniReview discusses some of the existing and well-known experimental in vitro and in vivo methods for studies of percutaneous penetration together with some more recent and promising methods. After this, some considerations and recommendations about advantages and limitations of the different methods and their relevance for the prediction of percutaneous penetration are given. Which method to prefer will depend on the product to be tested and the question asked. Regulatory guidelines exist for studies on percutaneous penetration, but researchers as well as regulatory bodies need to pay specific attention to the vehicles and solvents used in donor and sampling fluids so that it reflects in-use conditions as closely as possible. Based on available experimental data, mathematical models have been developed to aid predictions of skin penetration. The authors question the general use of the present mathematical models in hazard assessment, as they seem to ignore outliers among chemicals as well as the heterogeneity of skin barrier properties and skin conditions within the exposed populations. PMID:24373389
[Percutaneous therapy of painful arthritis].
Chlud, K
Pain in osteoarthrosis of the big weight bearing joints is either derived from periarticular ligaments, tendons, fasciae, muscles, bursae--peri-arthropathy as sign of decompensation--or from the reactive synovitis with or without effusion. NSAIDs systemically administered have been so far considered as first choice medication together with physical therapy. New pharmacokinetic data on the topical, percutaneous application of NSAIDs (ibuprofen, diclofenac, indomethacin, some salicylates and to a lesser degree for etofenamate and piroxicam) have demonstrated relevant advantages of the percutaneous route over the systemic one in soft tissue rheumatism. NSAIDs, mentioned above, locally administered as cream, gel or spray, quickly penetrate through the corneal layer of the skin at the site of application, reach high effective concentrations in subcutis, fasciae, tendons, ligaments and muscles, lesser in joint-capsule and -fluid indicating direct penetration. The blood levels of topical NSAIDs are extremely low with no systemic side effects, especially no gastric toxicity; however, local skin irritation is observed (1 to 2%). In contrast to this, systemic (oral) NSAIDs lead primarily via high blood levels to a much lesser concentration--only one tenth--in particular soft tissues with a high incidence of side effects. In conclusion the percutaneous application of certain NSAIDs has become a well established therapeutic regimen in painful osteoarthrosis and in all other inflammatory degenerative and posttraumatic alterations of soft tissue structures. PMID:2011838
[Percutaneous biopsy of the liver].
Skladaný, L; Jarcuska, P; Oltman, M; Hrusovský, S
Percutaneous liver biopsy represents the most specific examination of the nature and severity of liver diseases. P. Ehrlich was the first physician in history having done the intervention in 1880. The new history begins with the Menghini's publication on s.c. one-second biopsy in 1957. The present paper deals exclusively with diffuse diseases of the liver including the most frequent ones--virus hepatitis, alcohol and non-alcohol steatohepatitis. The contraindications include mainly coagulation disorders and non-cooperative patients. The percutaneous biopsy is mostly executed after ultrasonographic examination or under the control of various image-forming techniques and by means of various types of needles; the authors analyze advantages and disadvantages of individual techniques. If the contraindications are respected, the percutaneous biopsy is a safe method of examination, which may be done on out-patient basis. A large series of complications exists, but their frequency is generally low. Morbidity is referred in 0.2% of patients, the most frequent complications being pain and hypotension from vaso-vagal reactions, extensive intraperitoneal bleeding and hemobilia. Mortality is extremely low, the mean in large studies being 0.001%. PMID:14518095
Prosthetic lumbar disc replacement for degenerative disc disease.
Kulkarni, Arvind G; Diwan, Ashish D
Mechanical articulated device to replace intervertebral disc as a treatment for low back pain secondary to disc degeneration has emerged as a promising tool for selected patients. The potential advantages are prevention of adjacent segment degeneration, maintenance of mobility as well as avoidance of all the complications associated with fusion. The short-term results have been comparable to that of fusion, a few mid-term results have shown mixed outcome, but information on long-term results and performance are not available at present. The rationale for lumbar disc arthroplasty, indications, contraindications, the various artificial devices in the market and the concepts intrinsic to each of them, basic technique of insertion, complications are discussed and a brief summary of our experience with one of the devices is presented. PMID:16565543
Chondrule transport in protoplanetary discs
NASA Astrophysics Data System (ADS)
Goldberg, Aaron Z.; Owen, James E.; Jacquet, Emmanuel
Chondrule formation remains one of the most elusive early Solar system events. Here, we take the novel approach of employing numerical simulations to investigate chondrule origin beyond purely cosmochemical methods. We model the transport of generically produced chondrules and dust in a 1D viscous protoplanetary disc model in order to constrain the chondrule formation events. For a single formation event we are able to match analytical predictions of the memory they retain of each other (complementarity), finding that a large mass accretion rate (≳10-7 M⊙ yr-1) allows for delays on the order of the disc's viscous time-scale between chondrule formation and chondrite accretion. Further, we find older discs to be severely diminished of chondrules, with accretion rates ≲10-9 M⊙ yr-1 for nominal parameters. We then characterize the distribution of chondrule origins in both space and time, as functions of disc parameters and chondrule formation rates, in runs with continuous chondrule formation and both static and evolving discs. Our data suggest that these can account for the observed diversity between distinct chondrite classes, if some diversity in accretion time is allowed for.
Gravitoturbulence in magnetized protostellar discs
NASA Astrophysics Data System (ADS)
Riols, A.; Latter, H.
Gravitational instability (GI) features in several aspects of protostellar disc evolution, most notably in angular momentum transport, fragmentation, and the outbursts exemplified by FU Ori and EX Lupi systems. The outer regions of protostellar discs may also be coupled to magnetic fields, which could then modify the development of GI. To understand the basic elements of their interaction, we perform local 2D ideal and resistive magnetohydrodynamics simulations with an imposed toroidal field. In the regime of moderate plasma beta, we find that the system supports a hot gravitoturbulent state, characterized by considerable magnetic energy and stress and a surprisingly large Toomre parameter Q ≳ 10. This result has potential implications for disc structure, vertical thickness, ionization, etc. Our simulations also reveal the existence of long-lived and dense `magnetic islands' or plasmoids. Lastly, we find that the presence of a magnetic field has little impact on the fragmentation criterion of the disc. Though our focus is on protostellar discs, some of our results may be relevant for the outer radii of AGN.
Cobrahead Deformity in the Right Atrial Disc of a New-Generation Occlutech Figulla Flex II Atrial Septal Defect Occluder Device
Ural, Ertan; Sahin, Tayfun
Cobrahead deformity is a known (but uncommon) phenomenon associated with the left atrial disc of the Amplatzer or Occlutech Figulla septal occluder device during percutaneous transcatheter atrial septal defect closure. It has also been postulated that the right atrial disc of the Amplatzer septal occluder device might upon occasion exhibit the cobrahead malformation. To date, only one case report concerning the cobrahead deformity in the right atrial disc of an Amplatzer septal occluder has been published, if we discount a report published as a letter to the manufacturer. Here we present the first report (known to us) of a cobrahead deformity in the right atrial disc of an Occlutech Figulla Flex II atrial septal defect occluder device during transcatheter closure of a complex atrial septal defect. PMID:26504440
Boord, Mona
The laser is a tool that will augment the surgical techniques available to the veterinarian. When using the laser compared with traditional surgery there are multiple procedures that can be performed with much greater ease, and some procedures that previously could not be performed. Specialty and academic practices have used lasers for photodynamic therapy, lithotripsy of urinary calculi, and percutaneous disk ablation. This article will focus on the lasers use in dermatology. It is essential that the surgeon learn the basics of laser physics, how the laser interacts with tissue and the safety issues one needs to consider during its use. On deciding to use the laser the surgical techniques chosen should always be based on considering the advantages and disadvantages the laser has to offer. The use of biomedical lasers is a "cutting edge" technique now available to our veterinary field. PMID:16933481
Mackenzie, Shawn D; Brisson, Brigitte A; Gaitero, Luis; Caswell, Jeff L; Liao, Penting; Sinclair, Melissa; Chalmers, Heather J
Radiopaque gelified ethanol preparation has been described as a useful agent for treatment of humans with intervertebral disc protrusion. The material is injected into the nucleus pulposus under image guidance with intention to cause the protruded disc material to recede. Because treatment options for dogs with chronic protrusions are limited, new and minimally invasive treatments are desirable. The aim of this experimental, descriptive, prospective study was to assess the feasibility and safety of percutaneous injection of gelified ethanol into the lumbosacral intervertebral disc of dogs. Lumbosacral intervertebral discs of normal dogs (n = 9) were imaged with magnetic resonance imaging and then injected with gelified ethanol using image guidance. The accuracy of gelified ethanol placement in the nucleus pulposus and presence of leakage of the injected material were documented. Postinjection computed tomography (CT) findings (n = 9), short-term (n = 9) and long-term (n = 4) follow-up magnetic resonance imaging and CT findings were compared to document the distribution of the injected preparation and identify effects on adjacent tissues. Percutaneous injection of the intervertebral disc was successful in delivering radiopaque gelified ethanol to the nucleus pulposus in all dogs. Leakage of the injected material into the vertebral canal was present in three dogs immediately following injection and in another additional dog at 1 year following injection. All dogs tolerated the injection well and had no clinical adverse reactions within the study period. Findings indicated that injection of the nucleus pulposus of healthy dogs was well tolerated, even in the presence of mild leakage of material from the intervertebral disc. PMID:26626409
Black hole accretion disc impacts
NASA Astrophysics Data System (ADS)
Pihajoki, P.
We present an analytic model for computing the luminosity and spectral evolution of flares caused by a supermassive black hole impacting the accretion disc of another supermassive black hole. Our model includes photon diffusion, emission from optically thin regions and relativistic corrections to the observed spectrum and time-scales. We test the observability of the impact scenario with a simulated population of quasars hosting supermassive black hole binaries. The results indicate that for a moderate binary mass ratio of 0.3, and impact distances of 100 primary Schwarzschild radii, the accretion disc impacts can be expected to equal or exceed the host quasar in brightness at observed wavelength λ = 510 nm up to z = 0.6. We conclude that accretion disc impacts may function as an independent probe for supermassive black hole binaries. We release the code used for computing the model light curves to the community.
Foraminoplastic Superior Vertebral Notch Approach with Reamers in Percutaneous Endoscopic Lumbar Discectomy : Technical Note and Clinical Outcome in Limited Indications of Percutaneous Endoscopic Lumbar Discectomy
Yoon, Kang-Jun; Ha, Sang-Soo; Kang, Joon-Ki
To describe the details of the foraminoplastic superior vertebral notch approach (FSVNA) with reamers in percutaneous endoscopic lumbar discectomy (PELD) and to demonstrate the clinical outcomes in limited indications of PELD. Retrospective data were collected from 64 patients who underwent PELD with FSVNA from August 2012 to April 2014. Inclusion criteria were high grade migrated disc, high canal compromised disc, and disc protrusion combined with foraminal stenosis. The clinical outcomes were assessed using by the visual analogue scale (VAS), Oswestry Disability Index (ODI) and modified MacNab criteria. Complications related to the surgery were reviewed. The procedure used a unique approach, using the superior vertebral notch as the target and performing foraminoplasty with only reamers under C-arm control. The mean age of the 55 female and 32 male patients was 52.73 years. The mean F/U period was 12.2±4.2 months. Preoperative VAS (8.24±1.25) and ODI (67.8±15.4) score improved significantly at the last follow-up (VAS, 1.93±1.78; ODI, 17.14±15.7). Based on the modified MacNab criteria, excellent or good results were obtained in 95.3% of the patients. Postoperative transient dysthesia (n=2) and reoperation (n=1) due to recurred disc were reported. PELD with FSVNA could be a good method for treating lumbar disc herniation. This procedure may offer safe and efficacious results, especially in the relatively limited indications for PELD. PMID:26962427
Debris disc formation induced by planetary growth
NASA Astrophysics Data System (ADS)
Kobayashi, H.; Löhne, T.
Several hundred stars older than 10 million years have been observed to have infrared excesses. These observations are explained by dust grains formed by the collisional fragmentation of hidden planetesimals. Such dusty planetesimal discs are known as debris discs. In a dynamically cold planetesimal disc, collisional coagulation of planetesimals produces planetary embryos which then stir the surrounding leftover planetesimals. Thus, the collisional fragmentation of planetesimals that results from planet formation forms a debris disc. We aim to determine the properties of the underlying planetesimals in debris discs by numerically modelling the coagulation and fragmentation of planetesimal populations. The brightness and temporal evolution of debris discs depend on the radial distribution of planetesimal discs, the location of their inner and outer edges, their total mass, and the size of planetesimals in the disc. We find that a radially narrow planetesimal disc is most likely to result in a debris disc that can explain the trend of observed infrared excesses of debris discsvvv around G-type stars, for which planet formation occurs only before 100 million years. Early debris disc formation is induced by planet formation, while the later evolution is explained by the collisional decay of leftover planetesimals around planets that have already formed. Planetesimal discs with underlying planetesimals of radii ˜100 km at ≈30 au most readily explain the Spitzer Space Telescope 24 and 70 μm fluxes from debris discs around G-type stars.
Ultra-mini-percutaneous nephrolithotomy: A minimally-invasive option for percutaneous stone removal
Agrawal, Madhu Sudan; Agarwal, Ketan; Jindal, Tarun; Sharma, Manoj
Introduction: Percutaneous nephrolithotomy (PCNL) has witnessed rapid advancements, the latest being ultra-mini-percutaneous nephrolithotomy (UMP), which makes the use of 11–13F sheaths as compared to 24–30F sizes used in conventional PCNL. This miniaturization aims to reduce morbidity and improve patient outcomes. We evaluated the safety and efficacy of UMP and report our ourtcomes. Patients and Methods: A total of 120 patients underwent UMP from July 2012 to March 2014. These patients had a single unilateral renal stone measuring between 8 and 20 mm. All patients underwent UMP using a 3F nephroscope, 7.5F inner sheath, and 11F or 13F outer metallic cannula, which served as the Amplatz sheath. Stone fragmentation and clearance were achieved with holmium laser. No nephrostomy or stent was used routinely. Results: Complete stone fragmentation was achieved in 114 out of 120 patients (95%) using UMP; whereas the remaining 6 were converted into mini-PCNL using a 12.5F nephroscope and 15F Amplatz sheath. The mean operative time was 39.7 ± 15.4 min, and the mean postoperative hospital stay was 22.3 ± 2.2 h. Postoperatively, 6 (5%) patients had residual fragments measuring ≤4 mm. At the 2 weeks follow-up, the stone-free status was >99% (119/120). There were no significant postoperative complications. Conclusion: This study shows UMP to be an effective and safe procedure for managing stones up to 20 mm. This procedure offers an attractive alternative to shock wave lithotripsy and retrograde intrarenal surgery for managing small stones. PMID:27127356
Plasma disc decompression for contained cervical disc herniation: a randomized, controlled trial
Nardi, Pier Vittorio
Prospective case series studies have shown that plasma disc decompression (PDD) using the COBLATION SpineWand device (ArthroCare Corporation, Austin, TX) is effective for decompressing the disc nucleus in symptomatic contained cervical disc herniations. This prospective, randomized controlled clinical trial was conducted to evaluate the clinical outcomes of percutaneous PDD as compared to conservative care (CC) through 1 year. Patients (n = 115) had neck/arm pain >50 on the visual analog scale (VAS) pain scale and had failed at least 30 days of failed CC. Patients were randomly assigned to receive either PDD (n = 62) or CC (n = 58). Clinical outcome was determined by VAS pain score, neck disability index (NDI) score, and SF-36 health survey, collected at 6 weeks, 3 months, 6 months, and 1 year. The PDD group had significantly lower VAS pain scores at all follow-up time points (PDD vs. CC: 6 weeks, −46.87 ± 2.71 vs. −15.26 ± 1.97; 3 months, −53.16 ± 2.74 vs. −30.45 ± 2.59; 6 months, −56.22 ± 2.63 vs. −40.26 ± 2.56; 1 year, −65.73 ± 2.24 vs. −36.45 ± 2.86; GEE, P < 0.0001). PDD patients also had significant NDI score improvement over baseline when compared to CC patients at the 6 weeks (PDD vs. CC: −9.15 ± 1.06 vs. −4.61 ± 0.53, P < 0.0001) and 1 year (PDD vs. CC: −16.70 ± 0.29 vs. −12.40 ± 1.26, P = 0.005) follow-ups. PDD patients showed statistically significant improvement over baseline in SF-36 physical component summary scores when compared to CC patients at 6 weeks and 1 year (PDD vs. CC: 8.86 + 8.04 vs. 4.24 ± 3.79, P = 0.0004; 17.64 ± 10.37 vs. 10.50 ± 10.6, P = 0.0003, respectively). In patients who had neck/arm pain due to a contained cervical disc herniation, PDD was associated with significantly better clinical outcomes than a CC regimen. At 1 year, CC patients appeared to suffer a "relapse, showing signs of decline in most measurements, whereas PDD
Outcome of nucleoplasty in patients with radicular pain due to lumbar intervertebral disc herniation
Ogbonnaya, Sunny; Kaliaperumal, Chandrasekaran; Qassim, Abdulla; O'Sullivan, Michael
Background: Nucleoplasty (percutaneous lumbar disc decompression) is a minimally invasive procedure that utilizes radiofrequency energy as a treatment for symptomatic lumbar disc herniation, against open microdiscectomy, which would be the mainstay treatment modality. The literature reports a favorable outcome in up to 77% of patients at 6 months. Aim: To evaluate the effectiveness of nucleoplasty in the management of discogenic radicular pain. Materials and Methods: The medical notes of 33 patients, admitted for nucleoplasty between June 2006 and September 2007, were reviewed retrospectively. All had radicular pain, and contained herniated disc as seen on magnetic resonance imaging (MRI) of lumbosacral spine. Patients were followed up at 1 and 3 months post-procedure. The outcome measures employed in this study were satisfaction with symptoms and self-reported improvement. Results: Thirty-three cases were examined (18 males and 15 females). Twenty-seven procedures were performed with no complications and six were abandoned due to anatomical reasons. There were 18 and 15 cases of disc herniation at L5/S1 and L4/5 levels, respectively. Four weeks following the procedure, 13 patients reported improvement in symptoms, and 14 remained symptomatically the same and subsequently had open microdiscectomy. Conclusion: Nucleoplasty has been shown to be a safe and minimal-access procedure. Less than half of our selected cohort of patients reported symptomatic improvement at 1-month follow-up. We no longer offer this procedure to our patients. Possible reasons are discussed. PMID:23633860
Optical Discs: New Storage Media for Education.
ERIC Educational Resources Information Center
Helgerson, Linda W.
Discusses three new advances in the use of optical disc technology in education. Describes the storage formats and capabilities of the videodisc, the compact disc, and the optical write-once disc. Contrasts the three technologies in terms of their production requirements, the hardware involved, and some projected applications in education. (TW)
Acute Motor Weakness of Opposite Lower Extremity after Percutaneous Epidural Neuroplasty
Lim, Yong Seok; Park, Cheon Hee; Wee, Sang Woo; Sin, Sung Sik; Kim, Joon
Recently, percutaneous epidural neuroplasty has become widely used to treat radicular pain caused by spinal stenosis or a herniated intervertebral disc. A 19-year-old female patient suffering from left radicular pain caused by an L4-L5 intervertebral disc herniation underwent percutaneous epidural neuroplasty of the left L5 nerve root using a Racz catheter. After the procedure, the patient complained of acute motor weakness in the right lower leg, on the opposite site to where the neuroplasty was conducted. Emergency surgery was performed, and swelling of the right L5 nerve root was discovered. The patient recovered her motor and sensory functions immediately after the surgery. Theoretically, the injection of a large volume of fluid in a patient with severe spinal stenosis during epidural neuroplasty can increase the pressure on the opposite side of the epidural space, which may cause injury of the opposite nerve by barotrauma from a closed compartment. Practitioners should be aware of this potential complication. PMID:25852837
Electromagnetic Levitation of a Disc
ERIC Educational Resources Information Center
Valle, R.; Neves, F.; de Andrade, R., Jr.; Stephan, R. M.
This paper presents a teaching experiment that explores the levitation of a disc of ferromagnetic material in the presence of the magnetic field produced by a single electromagnet. In comparison to the classical experiment of the levitation of a sphere, the main advantage of the proposed laboratory bench is that the uniform magnetic field…
Optical Disc Applications in Libraries.
ERIC Educational Resources Information Center
Andre, Pamela Q. J.
Discusses a variety of library applications of optical disc storage technology, including CD-ROM, digital videodisc, and WORM. Research and development projects at the Library of Congress, National Library of Medicine, and National Agricultural Library are described, products offered by library networks are reviewed, and activities in academic and…
Engineered microporosity: enhancing the early regenerative potential of decellularized temporomandibular joint discs.
Juran, Cassandra M; Dolwick, M Franklin; McFetridge, Peter S
The temporomandibular joint (TMJ) disc is susceptible to numerous pathologies that may lead to structural degradation and jaw dysfunction. The limited treatment options and debilitating nature of severe temporomandibular disorders has been the primary driving force for the introduction and development of TMJ disc tissue engineering as an approach to alleviate this important clinical issue. This study aimed to evaluate the efficacy of laser micropatterning (LMP) ex vivo-derived TMJ disc scaffolds to enhance cellular integration, a major limitation to the development of whole tissue implant technology. LMP was incorporated into the decellularized extracellular matrix scaffold structure using a 40 W CO2 laser ablation system to drill an 8×16 pattern with a bore diameter of 120 μm through the scaffold thickness. Disc scaffolds were seeded with human neonatal-derived umbilical cord mesenchymal stem cells differentiated into chondrocytes at a density of 900 cells per mm(2) and then assessed on days 1, 7, 14, and 21 of culture. Results derived from histology, PicoGreen DNA quantification, and cellular metabolism assays indicate that the LMP scaffolds improve cellular remodeling compared to the unworked scaffold over the 21-day culture period. Mechanical analysis further supports the use of the LMP showing the compressive properties of the LMP constructs closely represent native disc mechanics. The addition of an artificial path of infiltration by LMP culminated in improved chondrocyte adhesion, dispersion, and migration after extended culture aiding in recapitulating the native TMJ disc characteristics. PMID:25319941
Engineered Microporosity: Enhancing the Early Regenerative Potential of Decellularized Temporomandibular Joint Discs
Juran, Cassandra M.; Dolwick, M. Franklin
The temporomandibular joint (TMJ) disc is susceptible to numerous pathologies that may lead to structural degradation and jaw dysfunction. The limited treatment options and debilitating nature of severe temporomandibular disorders has been the primary driving force for the introduction and development of TMJ disc tissue engineering as an approach to alleviate this important clinical issue. This study aimed to evaluate the efficacy of laser micropatterning (LMP) ex vivo-derived TMJ disc scaffolds to enhance cellular integration, a major limitation to the development of whole tissue implant technology. LMP was incorporated into the decellularized extracellular matrix scaffold structure using a 40 W CO2 laser ablation system to drill an 8×16 pattern with a bore diameter of 120 μm through the scaffold thickness. Disc scaffolds were seeded with human neonatal-derived umbilical cord mesenchymal stem cells differentiated into chondrocytes at a density of 900 cells per mm2 and then assessed on days 1, 7, 14, and 21 of culture. Results derived from histology, PicoGreen DNA quantification, and cellular metabolism assays indicate that the LMP scaffolds improve cellular remodeling compared to the unworked scaffold over the 21-day culture period. Mechanical analysis further supports the use of the LMP showing the compressive properties of the LMP constructs closely represent native disc mechanics. The addition of an artificial path of infiltration by LMP culminated in improved chondrocyte adhesion, dispersion, and migration after extended culture aiding in recapitulating the native TMJ disc characteristics. PMID:25319941
Percutaneous Cryoablation for Liver Cancer
Niu, Li-Zhi; Li, Jia-Liang; Xu, Ke-Cheng
Based on the primary tumor site, liver cancer can be divided into two categories: (1) primary liver cancer and (2) metastatic cancer to the liver from a distant primary site. Guided cryoablation via many imaging methods induces iceball formation and tumor necrosisand is an attractive option for treating unresectable hepatocellular carcinoma (HCC) and metastatic liver cancer. There are several advantages to using cryoablation for the treatment of liver cancer: it can be performed percutaneously, intraoperatively, and laparoscopically; iceball formation can be monitored; it has little impact on nearby large blood vessels; and it induces a cryo-immunological response in situ. Clinically, primary research has shown that percutaneous cryoablation of liver cancer is relatively safe and efficient, and it can be combined with other methods, such as radiation therapy, chemotherapy, and immunology, to control disease. Although research is preliminary, cryosurgery is fast becoming an alternative treatment method for HCC or liver tumors. Here, we review the mechanisms of liver tumor cryoablation, cryoablation program selection, clinical efficiency, and complications following treatment. PMID:26355719
Results of arthrospine assisted percutaneous technique for lumbar discectomy
Kaushal, Mohinder
Background: Avaialable minimal invasive arthro/endoscopic techniques are not compatible with 30 degree arthroscope which orthopedic surgeons uses in knee and shoulder arthroscopy. Minimally invasive "Arthrospine assisted percutaneous technique for lumbar discectomy" is an attempt to allow standard familiar microsurgical discectomy and decompression to be performed using 30° arthroscope used in knee and shoulder arthroscopy with conventional micro discectomy instruments. Materials and Methods: 150 patients suffering from lumbar disc herniations were operated between January 2004 and December 2012 by indiginously designed Arthrospine system and were evaluated retrospectively. In lumbar discectomy group, there were 85 males and 65 females aged between 18 and 72 years (mean, 38.4 years). The delay between onset of symptoms to surgery was between 3 months to 7 years. Levels operated upon included L1-L2 (n = 3), L2-L3 (n = 2), L3-L4 (n = 8), L4-L5 (n = 90), and L5-S1 (n = 47). Ninety patients had radiculopathy on right side and 60 on left side. There were 22 central, 88 paracentral, 12 contained, 3 extraforaminal, and 25 sequestrated herniations. Standard protocol of preoperative blood tests, x-ray LS Spine and pre operative MRI and pre anaesthetic evaluation for anaesthesia was done in all cases. Technique comprised localization of symptomatic level followed by percutaneous dilatation and insertion of a newly devised arthrospine system devise over a dilator through a 15 mm skin and fascial incision. Arthro/endoscopic discectomy was then carried out by 30° arthroscope and conventional disc surgery instruments. Results: Based on modified Macnab's criteria, of 150 patients operated for lumbar discectomy, 136 (90%) patients had excellent to good, 12 (8%) had fair, and 2 patients (1.3%) had poor results. The complications observed were discitis in 3 patients (2%), dural tear in 4 patients (2.6%), and nerve root injury in 2 patients (1.3%). About 90% patients were able
Peripheral disc margin shape and internal disc derangement: imaging correlation in significantly painful discs identified at provocation lumbar discography.
Bartynski, W S; Rothfus, W E
Annular margin shape is used to characterize lumbar disc abnormality on CT/MR imaging studies. Abnormal discs also have internal derangement including annular degeneration and radial defects. The purpose of this study was to evaluate potential correlation between disc-margin shape and annular internal derangement on post-discogram CT in significantly painful discs encountered at provocation lumbar discography (PLD). Significantly painful discs were encountered at 126 levels in 86 patients (47 male, 39 female) studied by PLD where no prior surgery had been performed and response to intradiscal lidocaine after provocation resulted in either substantial/total relief or no improvement after lidocaine administration. Post-discogram CT and discogram imaging was evaluated for disc-margin characteristics (bulge/protrusion), features of disc internal derangement (radial annular defect [RD: radial tear/fissure/annular gap], annular degeneration) and presence/absence of discographic contrast leakage. In discs with focal protrusion, 50 of 63 (79%) demonstrated Grade 3 RD with 13 (21%) demonstrating severe degenerative change only. In discs with generalized-bulge-only, 48 of 63 (76%) demonstrated degenerative change only (primarily Dallas Grade 3) with 15 of 63 (24%) demonstrating a RD (Dallas Grade 3). Differences were highly statistically significant (p<0.001). Pain elimination with intra-discal lidocaine correlated with discographic contrast leakage (p<0.001). Disc-margin shape correlates with features of internal derangement in significantly painful discs encountered at PLD. Discs with focal protrusion typically demonstrate RD while generalized bulging discs typically demonstrated degenerative changes only (p<0.001). Disc-margin shape may provide an important imaging clue to the cause of chronic discogenic low back pain. PMID:22681741
Peripheral Disc Margin Shape and Internal Disc Derangement: Imaging Correlation in Significantly Painful Discs Identified at Provocation Lumbar Discography
Bartynski, W.S.; Rothfus, W.E.
Summary Annular margin shape is used to characterize lumbar disc abnormality on CT/MR imaging studies. Abnormal discs also have internal derangement including annular degeneration and radial defects. The purpose of this study was to evaluate potential correlation between disc-margin shape and annular internal derangement on post-discogram CT in significantly painful discs encountered at provocation lumbar discography (PLD). Significantly painful discs were encountered at 126 levels in 86 patients (47 male, 39 female) studied by PLD where no prior surgery had been performed and response to intradiscal lidocaine after provocation resulted in either substantial/total relief or no improvement after lidocaine administration. Post-discogram CT and discogram imaging was evaluated for disc-margin characteristics (bulge/protrusion), features of disc internal derangement (radial annular defect [RD: radial tear/fissure/annular gap], annular degeneration) and presence/absence of discographic contrast leakage. In discs with focal protrusion, 50 of 63 (79%) demonstrated Grade 3 RD with 13 (21%) demonstrating severe degenerative change only. In discs with generalized-bulge-only, 48 of 63 (76%) demonstrated degenerative change only (primarily Dallas Grade 3) with 15 of 63 (24%) demonstrating a RD (Dallas Grade 3). Differences were highly statistically significant (p<0.001). Pain elimination with intra-discal lidocaine correlated with discographic contrast leakage (p<0.001). Disc-margin shape correlates with features of internal derangement in significantly painful discs encountered at PLD. Discs with focal protrusion typically demonstrate RD while generalized bulging discs typically demonstrated degenerative changes only (p<0.001). Disc-margin shape may provide an important imaging clue to the cause of chronic discogenic low back pain. PMID:22681741
Total analysis systems with Thermochromic Etching Discs technology.
Avella-Oliver, Miquel; Morais, Sergi; Carrascosa, Javier; Puchades, Rosa; Maquieira, Ángel
A new analytical system based on Thermochromic Etching Discs (TED) technology is presented. TED comprises a number of attractive features such as track independency, selective irradiation, a high power laser, and the capability to create useful assay platforms. The analytical versatility of this tool opens up a wide range of possibilities to design new compact disc-based total analysis systems applicable in chemistry and life sciences. In this paper, TED analytical implementation is described and discussed, and their analytical potential is supported by several applications. Microarray immunoassay, immunofiltration assay, solution measurement, and cell culture approaches are herein addressed in order to demonstrate the practical capacity of this system. The analytical usefulness of TED technology is herein demonstrated, describing how to exploit this tool for developing truly integrated analytical systems that provide solutions within the point of care framework. PMID:25310278
Sealing arrangement with annular flexible disc
Pennell, William E.; Honigsberg, Charles A.
Fluid sealing arrangements including an annular shaped flexible disc having enlarged edges disposed within channel-shaped annular receptacles which are spaced from one another. The receptacles form an annular region for contacting and containing the enlarged edges of the disc, and the disc is preloaded to a conical configuration. The disc is flexibly and movably supported within the receptacles so that unevenly distributed relative motion between the components containing the receptacles is accommodated without loss of sealing contact between the edges of the disc and the walls of the receptacles.
In vitro biomechanics of cervical disc arthroplasty with the ProDisc-C total disc implant.
DiAngelo, Denis J; Foley, Kevin T; Morrow, Brian R; Schwab, John S; Song, Jung; German, John W; Blair, Eve
An in vitro biomechanical study was conducted to compare the effects of disc arthroplasty and anterior cervical fusion on cervical spine biomechanics in a multilevel human cadaveric model. Three spine conditions were studied: harvested, single-level cervical disc arthroplasty, and single-level fusion. A programmable testing apparatus was used that replicated physiological flexion/extension, lateral bending, and axial rotation. Measurements included vertebral motion, applied load, and bending moments. Relative rotations at the superior, treated, and inferior motion segment units (MSUs) were normalized with respect to the overall rotation of those three MSUs and compared using a one-way analysis of variance with Student-Newman-Keuls test (p < 0.05). Simulated fusion decreased motion across the treated site relative to the harvested and disc arthroplasty conditions. The reduced motion at the treated site was compensated at the adjacent segments by an increase in motion. For all modes of testing, use of an artificial disc prosthesis did not alter the motion patterns at either the instrumented level or adjacent segments compared with the harvested condition, except in extension. PMID:15636563
From the Solar Neighbourhood to the Galactic Disc(s)
NASA Astrophysics Data System (ADS)
Casagrande, L.
We present a re-analysis of the Geneva-Copenhagen Survey (GCS), based on improved effective temperature and metallicity scales, which also provide a better match to theoretical isochrones. The latter are used for a Bayesian investigation on stellar ages. With respect to previous analyses, our stars are on average 100 K hotter and 0.1 dex more metal rich, which shifts the peak of the metallicity distribution function (MDF) around the solar value. From Strömgren photometry we are able to derive for the first time a proxy for alpha elements, which enables us to perform a tentative dissection of the chemical thin and thick disc. We find evidence for the latter being composed of an old, mildly but systematically alpha-enhanced population that extends to super solar metallicities. These findings help to constrain different processes potentially relevant in the build-up of the Milky Way disc.
Intradural herniation of lumbar intervertebral discs.
Hodge, C J; Binet, E F; Kieffer, S A
A case of intradural rupture of a lumbar intervertebral disc is reported, and the literature is reviewed. The majority of intradural disc herniations occur at the L4--5 level. These patients usually have neurologic deficits more severe than those found in the much more common extradural disc herniations. The myelographic picture varies from an irregularly marginated intradural lesion overlying the disc space to a complete block. The common factor allowing intradural disc herniation is probably dense adhesions between the dura and the posterior longitudinal ligament, preventing the more common lateral extradural disc herniation. Intradural disc herniation should be included in the differential diagnosis of lumbar intradural lesions causing nerve root or cauda equina compression. PMID:741242
Transgluteal CT-Guided Percutaneous Renal Access for Percutaneous Nephrolithotomy in a Pelvic Horseshoe Kidney
Mullins, Ryan J.; Dauw, Casey A.; Borofsky, Michael S.; York, Nadya; Patel, Aashish A.
Abstract CT-guided percutaneous renal access has been described as a safe and effective access technique in patients with complex anatomy, including ectopic kidney, retrorenal colon, spinal dysraphism, hepatomegaly, and splenomegaly. In comparison to conventional intraoperative fluoroscopic-guided access, CT imaging allows for delineation of surrounding structures that are at risk for injury during percutaneous access. However, previous reports indicate that pelvic kidneys might be inaccessible percutaneously without laparoscopic assistance. Herein, we present a novel transgluteal route to renal access for percutaneous nephrolithotomy (PCNL) in a patient with a pelvic horseshoe kidney and severe spinal deformity.
Lewis, Owen; Stogran, Edmund M.
Laser apparatus is described wherein an active laser element, such as the disc of a face-pumped laser, is mounted in a housing such that the weight of the element is supported by glass spheres which fill a chamber defined in the housing between the walls of the housing and the edges of the laser element. The uniform support provided by the spheres enable the chamber and the pump side of the laser element to be sealed without affecting the alignment or other optical properties of the laser element. Cooling fluid may be circulated through the sealed region by way of the interstices between the spheres. The spheres, and if desired also the cooling fluid may contain material which absorbs radiation at the wavelength of parasitic emissions from the laser element. These parasitic emissions enter the spheres through the interface along the edge surface of the laser element and it is desirable that the index of refraction of the spheres and cooling fluid be near the index of refraction of the laser element. Thus support, cooling, and parasitic suppression functions are all accomplished through the use of the arrangement.
[Innervation of the intervertebral disc].
García-Cosamalón, José; Fernández-Fernández, Javier; González-Martínez, Emilio; Ibáñez-Plágaro, Javier; Robla Costales, Javier; Martínez-Madrigal, Milton; López Muñíz, Alfonso; del Valle, Miguel Enrique; Vega, José Antonio
Until very recently, intervertebral disc innervation was a subject of considerable debate. Nowadays, the introduction of inmunohistochemical techniques associated to specific antibodies and studies with retrograde tracers in nerves have allowed greater understanding of disc innervation in physiological and pathological conditions and also endings characteristics and their patterns of distribution in both situations. The existing controversies regarding structural basis of discogenic pain, have raised the interest of knowing the influence of innervation in back pain from discal origin and its characteristics. Today, we know that pathologic neoinnervation accompanying radial fissures is an important factor in the genesis of discogenic pain; within a complex mechanism in which other neurobiomechemical, inflammatory and biomechanical factors are involved. PMID:23582224
Ultrasound-guided percutaneous thoracoabdominal biopsy.
Ojalehto, M; Tikkakoski, T; Rissanen, T; Apaja-Sarkkinen, M
This review will discuss the benefits and disadvantages of ultrasound-guided percutaneous fine-needle aspiration and cutting needle biopsies. Clinical efficacy, cost-effectiveness, some controversies and safety will be reviewed. PMID:12010294
Percutaneous umbilical cord blood sampling - series (image)
... or blood disorder, your doctor may recommend percutaneous umbilical cord blood sampling (PUBS), which is performed at ... sample of the fetus' blood directly from the umbilical cord. The sample is then analyzed for genetic ...
Percutaneous needle biopsy of the irradiated skeleton
Edeiken, B.; deSantos, L.A.
Percutaneous needle biopsy was performed in 20 patients who had radiologic abnormalities after irradiation of the skeleton. The biopsies were performed to determine the nature of the bone changes and to differentiate radiation necrosis from metastases or local tumor extension. Eleven patients had tumors, two of which were radiation-induced sarcomas; nine patients did not show evidence of tumor. One patient had osteomyelitis rather than the suspected tumor. The value of percutaneous needle biopsy in the postirradiated skeleton is discussed.
Percutaneous transcatheter snare vegetectomy in a child.
Saltık, I Levent; Atik, Sezen U; Eroglu, Ayşe G
Surgical vegetectomy may be indicated in patients with unresolving sepsis, heart failure, recurrent embolism, or the presence of large vegetations >10 mm in size. Percutaneous vegetectomy using a snare may be a reasonable option instead of open-heart surgery in selected patients. We describe the case of a patient with operated tetralogy of Fallot and infective endocarditis who underwent vegetectomy via a percutaneous approach. PMID:26817598
Hydrodynamic instability in eccentric astrophysical discs
NASA Astrophysics Data System (ADS)
Barker, A. J.; Ogilvie, G. I.
Eccentric Keplerian discs are believed to be unstable to three-dimensional hydrodynamical instabilities driven by the time-dependence of fluid properties around an orbit. These instabilities could lead to small-scale turbulence, and ultimately modify the global disc properties. We use a local model of an eccentric disc, derived in a companion paper, to compute the non-linear vertical (`breathing mode') oscillations of the disc. We then analyse their linear stability to locally axisymmetric disturbances for any disc eccentricity and eccentricity gradient using a numerical Floquet method. In the limit of small departures from a circular reference orbit, the instability of an isothermal disc is explained analytically. We also study analytically the small-scale instability of an eccentric neutrally stratified polytropic disc with any polytropic index using a Wentzel-Kramers-Brillouin (WKB) approximation. We find that eccentric discs are generically unstable to the parametric excitation of small-scale inertial waves. The non-linear evolution of these instabilities should be studied in numerical simulations, where we expect them to lead to a decay of the disc eccentricity and eccentricity gradient as well as to induce additional transport and mixing. Our results highlight that it is essential to consider the three-dimensional structure of eccentric discs, and their resulting vertical oscillatory flows, in order to correctly capture their evolution.
Proto-planetary disc evolution and dispersal
NASA Astrophysics Data System (ADS)
Rosotti, Giovanni Pietro
Planets form from gas and dust discs in orbit around young stars. The timescale for planet formation is constrained by the lifetime of these discs. The properties of the formed planetary systems depend thus on the evolution and final dispersal of the discs, which is the main topic of this thesis. Observations reveal the existence of a class of discs called "transitional", which lack dust in their inner regions. They are thought to be the last stage before the complete disc dispersal, and hence they may provide the key to understanding the mechanisms behind disc evolution. X-ray photoevaporation and planet formation have been studied as possible physical mechanisms responsible for the final dispersal of discs. However up to now, these two phenomena have been studied separately, neglecting any possible feedback or interaction. In this thesis we have investigated what is the interplay between these two processes. We show that the presence of a giant planet in a photo-evaporating disc can significantly shorten its lifetime, by cutting the inner regions from the mass reservoir in the exterior of the disc. This mechanism produces transition discs that for a given mass accretion rate have larger holes than in models considering only X-ray photo-evaporation, constituting a possible route to the formation of accreting transition discs with large holes. These discs are found in observations and still constitute a puzzle for the theory. Inclusion of the phenomenon called "thermal sweeping", a violent instability that can destroy a whole disc in as little as 10 4 years, shows that the outer disc left can be very short-lived (depending on the X-ray luminosity of the star), possibly explaining why very few non accreting transition discs are observed. However the mechanism does not seem to be efficient enough to reconcile with observations. In this thesis we also show that X-ray photo-evaporation naturally explains the observed correlation between stellar masses and accretion
Factors regulating viable cell density in the intervertebral disc: blood supply in relation to disc height
Boubriak, Olga A; Watson, Natasha; Sivan, Sarit S; Stubbens, Naomi; Urban, Jill P G
The intervertebral disc is an avascular tissue, maintained by a small population of cells that obtain nutrients mainly by diffusion from capillaries at the disc–vertebral body interface. Loss of this nutrient supply is thought to lead to disc degeneration, but how nutrient supply influences viable cell density is unclear. We investigated two factors that influence nutrient delivery to disc cells and hence cell viability: disc height and blood supply. We used bovine caudal discs as our model as these show a gradation in disc height. We found that although disc height varied twofold from the largest to the smallest disc studied, it had no significant effect on cell density, unlike the situation found in articular cartilage. The density of blood vessels supplying the discs was markedly greater for the largest disc than the smallest disc, as was the density of pores allowing capillary penetration through the bony endplate. Results indicate that changes in blood vessels in the vertebral bodies supplying the disc, as well as changes in endplate architecture appear to influence density of cells in intervertebral discs. PMID:23311982
Surface plasmon resonance-enabled antibacterial digital versatile discs
NASA Astrophysics Data System (ADS)
Dou, Xuan; Chung, Pei-Yu; Jiang, Peng; Dai, Jianli
We report the achievement of effective sterilization of exemplary bacteria including Escherichia coli and Geobacillus stearothermophilus spores on a digital versatile disc (DVD). The spiral arrangement of aluminum-covered pits generates strong surface plasmon resonance (SPR) absorption of near-infrared light, leading to high surface temperature that could even damage the DVD plastics. Localized protein denaturation and high sterilization efficiency have been demonstrated by using a fluorescence microscope and cell cultures. Numerical simulations have also been conducted to model the SPR properties and the surface temperature distribution of DVDs under laser illumination. The theoretical predictions agree reasonably well with the experimental results.
Intervertebral disc extrusion in six cats.
Knipe, M F; Vernau, K M; Hornof, W J; LeCouteur, R A
Existing reports concerning intervertebral disc disease (IVDD) have focused almost exclusively on dogs, although a small number of individual case reports of IVDD of cats has been published. The medical records of six cats with IVDD were reviewed. Radiographic studies confirmed narrowed intervertebral disc spaces, mineralised intervertebral discs, and one or more extradural compressive lesions of the spinal cord in each cat. All disc extrusions were located in the thoracolumbar region. Surgical decompression of the spinal cord was achieved in all cats by means of hemilaminectomy and removal of compressive extradural material confirmed to be degenerative disc material. Good to excellent neurological recovery was noted in five of the six cats included in this report. Based on this review, it appears that IVDD of cats has many similarities to IVDD of dogs, and that healthy cats with acute intervertebral disc extrusion(s) respond favourably to surgical decompression of the spinal cord. PMID:11876633
Thermal protection during percutaneous thermal ablation procedures: interest of carbon dioxide dissection and temperature monitoring.
Buy, Xavier; Tok, Chung-Hong; Szwarc, Daniel; Bierry, Guillaume; Gangi, Afshin
Percutaneous image-guided thermal ablation of tumor is widely used, and thermal injury to collateral structures is a known complication of this technique. To avoid thermal damage to surrounding structures, several protection techniques have been reported. We report the use of a simple and effective protective technique combining carbon dioxide dissection and thermocouple: CO(2) displaces the nontarget structures, and its low thermal conductivity provides excellent insulation; insertion of a thermocouple in contact with vulnerable structures achieves continuous thermal monitoring. We performed percutaneous thermal ablation of 37 tumors in 35 patients (4 laser, 10 radiofrequency, and 23 cryoablations) with protection of adjacent vulnerable structures by using CO(2) dissection combined with continuous thermal monitoring with thermocouple. Tumor locations were various (19 intra-abdominal tumors including 4 livers and 9 kidneys, 18 musculoskeletal tumors including 11 spinal tumors). CO(2) volume ranged from 10 ml (epidural space) to 1500 ml (abdominal). Repeated insufflations were performed if necessary, depending on the information given by the thermocouple and imaging control. Dissection with optimal thermal protection was achieved in all cases except two patients where adherences (one postoperative, one arachnoiditis) blocked proper gaseous distribution. No complication referred to this technique was noted. This safe, cost-effective, and simple method increases the safety and the success rate of percutaneous thermal ablation procedures. It also offers the potential to increase the number of tumors that can be treated via a percutaneous approach. PMID:19219496
Thermal Protection During Percutaneous Thermal Ablation Procedures: Interest of Carbon Dioxide Dissection and Temperature Monitoring
Buy, Xavier; Tok, Chung-Hong; Szwarc, Daniel; Bierry, Guillaume; Gangi, Afshin
Percutaneous image-guided thermal ablation of tumor is widely used, and thermal injury to collateral structures is a known complication of this technique. To avoid thermal damage to surrounding structures, several protection techniques have been reported. We report the use of a simple and effective protective technique combining carbon dioxide dissection and thermocouple: CO{sub 2} displaces the nontarget structures, and its low thermal conductivity provides excellent insulation; insertion of a thermocouple in contact with vulnerable structures achieves continuous thermal monitoring. We performed percutaneous thermal ablation of 37 tumors in 35 patients (4 laser, 10 radiofrequency, and 23 cryoablations) with protection of adjacent vulnerable structures by using CO{sub 2} dissection combined with continuous thermal monitoring with thermocouple. Tumor locations were various (19 intra-abdominal tumors including 4 livers and 9 kidneys, 18 musculoskeletal tumors including 11 spinal tumors). CO{sub 2} volume ranged from 10 ml (epidural space) to 1500 ml (abdominal). Repeated insufflations were performed if necessary, depending on the information given by the thermocouple and imaging control. Dissection with optimal thermal protection was achieved in all cases except two patients where adherences (one postoperative, one arachnoiditis) blocked proper gaseous distribution. No complication referred to this technique was noted. This safe, cost-effective, and simple method increases the safety and the success rate of percutaneous thermal ablation procedures. It also offers the potential to increase the number of tumors that can be treated via a percutaneous approach.
Endoscopic Trans-iliac Approach to L5-S1 Disc and Foramen – A Report on Clinical Experience
Osman, Said G; Sherlekar, Sandeep; Malik, Atif; Winters, Charles; Grewal, PK; Narayanan, Malini; Gemechu, Nigussie
Background The lumbosacral junction is a difficult area for spine surgery because of the complex anatomy. In the era of minimally invasive spine surgery, the presence of the iliac wing has, at the level of lumbosacral junction, created a major obstacle in the paths of two of the major approaches, namely, the direct lateral and percutaneous posterolateral endoscopic approaches. A trans-iliac cadaver study published by the senior author and co-workers in 1997, suggested the possibility of an alternative approach to the lumbosacral junction. Purpose To determine the feasibility of percutaneous, endoscopic trans-iliac approach to the L5-S1 disc and foramen Study Design Prospective case series study. Materials and Methods 15 consecutive patients undergoing the transiliac approach to L5-S1 disc and foramen were included in the study. Pre- and postoperative visual analogue scale (VAS); Oswestry Disability Index (ODI); and intra-operative blood loss and operative time, were obtained for the study. Preoperative MRI or CT scan was used to determine the need for trans-iliac access. The procedure was performed with the patient in prone position and under monitored sedation for decompression. Endotracheal anesthesia was used for fusion cases. The transiliac access was established with a cannulated drill or core drill through the iliac wing. Once the trans-iliac window had been created, the rest of the procedure proceeded as for percutaneous endoscopic transforaminal decompression and fusion. Results 15 patients (9 male and 6 female) participated in the study. The VAS for back and leg pain significantly improved in all patients. The ODI dropped by more than 50%. There was minimal blood loss, and transient post-operative dysesthesia in 2 cases which resolved after 3 weeks. Conclusion Endoscopic trans-iliac approach to the L5-S1 disc and foramen is feasible and safe. Decompression can be performed safely via trans-iliac access with minimal blood loss, and in a short operative time
Disc repositioning: does it really work?
Gonçalves, João Roberto; Cassano, Daniel Serra; Rezende, Luciano; Wolford, Larry M
Although limited, there is evidence to support the assumption that temporomandibular joint (TMJ) articular disc repositioning indeed works; to date, there is no evidence that TMJ articular disc repositioning does not work. Despite the controversy among professionals in private practice and academia, TMJ articular disc repositioning is a procedure based on (still limited) evidence; the opposition is based solely on clinical preference and influenced by the ability to perform it or not. PMID:25483446
Minimal gauge vitrectomy for optic disc pit maculopathy: Our results
Kumar, Atul; Gogia, Varun; Nagpal, Ritu; Roy, Sangeeta; Gupta, Shikha
The purpose of the study was to describe the surgical technique and clinical outcomes of pars plana vitrectomy without laser or gas tamponade in cases with optic disc pit maculopathy at our centre. Six eyes of six consecutive patients presenting with unilateral optic disc pit maculopathy were enrolled. Preoperative optical coherence tomography (OCT) was performed to determine the presence and extent of schisis and macular detachment. All eyes underwent 23-gauge pars plana vitrectomy with induction of posterior vitreous detachment (PVD) and internal limiting membrane (ILM) peeling and eyes were closed under fluid. Patients were followed up for at least 12 months post-surgery. Median age of patients was 22.5 years. Five of six eyes had neurosensory detachment (NSD) at the presentation; whereas, inner layer schisis was present in all patients. None of the patients had any evidence of vitreomacular or vitreopapillary adhesion or PVD either clinically or on OCT. Inner and outer retinal schisis resolved in all eyes after follow-up of at least 6 months. Resolution of subretinal fluid in eyes with NSD was seen in 4 of 5 eyes. There was a significant visual acuity improvement from mean preoperative visual acuity of 0.79 logarithm of the minimum angle of resolution (logMAR) units to 0.36 logMAR units at 12 months (P = 0.001). Thus, vitrectomy with ILM peeling and PVD induction alone could achieve good functional outcomes in cases with optic disc pit maculopathy. PMID:26862100
Real-time loop-mediated isothermal DNA amplification in compact disc micro-reactors.
Santiago-Felipe, Sara; Tortajada-Genaro, Luis A; Carrascosa, Javier; Puchades, Rosa; Maquieira, Ángel
An integrated device composed of micro-reactors embedded onto compact discs is proposed for real-time targeted DNA determination. The method principle is based on in-disc loop-mediated isothermal amplification (iD-LAMP) and quantitative optical read-out by a disc drive. In the presence of a target, the turbidimetric or colorimetric properties of reaction solution change, and the transmitted intensity of the disc drive laser modifies according to reaction yield. Monitoring real-time curves allowed the quantitative determination of DNA template amounts. The best amplification/detection results were obtained with micro-reactors (2mm diameter and 1.1mm in depth) drilled on a digital video disc (DVD) and detection based on the colorimetric mode. As proof-of-concept, the assay was applied to detect pathogenic bacteria Salmonella spp. and to identify bovine meat in food samples. Ninety-six samples were simultaneously analysed in 15 min, with high selectivity and sensitivity (5 CFU/mL and 10 µg/g for bacteria and meat, respectively). The in-disc results were comparable to those obtained by conventional LAMP or qPCR approaches. The developed device allows low sample and reagent consumption (3 µL of reaction), portability, ease-of-use, and rapid low-cost high-throughput analyses. PMID:26716424
Unsteady flow over disc turbine blades
NASA Astrophysics Data System (ADS)
Popiolek, Z.; Whitelaw, J. H.; Yianneskis, M.
Measurements are presented of the mean and turbulence structure of the trailing vortices produced over disc turbine blades in stirred vessels. The results were obtained by ensemble-averaging the velocities measured by laser-Doppler anemometry over intervals of one degree of revolution and are compared with results obtained by ensemble-averaging over the whole 360 deg cycle. A vortical pattern was permanently present up to 20 degrees behind each blade, and was subjected to an erratic motion due to the formation of a whirlpool type of vortex in the free surface of the water. The velocities in the vortices were of the order of 0.25 of the blade tip velocity, V(tip). The measured kinetic energy of turbulence reached maxima of 0.19 V(tip)squared and the fluctuating quantities measured indicated that strong anisotropy prevails in the impeller stream. Comparison of turbulence results with those obtained by sampling over the whole 360 degrees of revolution shows that the former can be overestimated by as much as four times.
Clinical results of XMR-assisted percutaneous transforaminal endoscopic lumbar discectomy
Background Although percutaneous endoscopic lumbar discectomy (PELD) has shown favorable outcomes in the majority of lumbar discectomy cases, there were also some failures. The most common cause of failure is the incomplete removal of disc fragments. The skin entry point for the guide-needle trajectory and the optimal placement of the working sleeve are largely blind, which might lead to the inadequate removal of disc fragments. The objective of this study was to present our early experiences with image-guided PELD using a specially designed fluoroscope with magnetic resonance imaging-equipped operative suite (XMR) for the treatment of lumbar disc herniation. Methods This prospective study included 89 patients who had undergone PELD via the transforaminal approach using an XMR protocol. Pre- and postoperative examinations (at 12 weeks) included a detailed clinical history, visual analogue scale (VAS), Oswestry disability index (ODI), and radiological workups. The results were categorized as excellent, good, fair, and poor according to MacNab's criteria. At the final follow-up, the minimum follow-up time for the subjects was 2 years. The need for revision surgeries and postoperative complications were noted on follow-up. Results Postoperative mean ODI decreased from 67.4% to 5.61%. Mean VAS score for back and leg pain improved significantly from 4 to 2.3 and from 7.99 to 1.04, respectively. Four (4.49%) patients underwent a second-stage PELD after intraoperative XMR had shown remnant fragments after the first stage. As per MacNab's criteria, 76 patients (85.4%) showed excellent, 8 (8.89%) good, 3 (3.37%) fair, and 2 (2.25) poor results. Four (4.49%) patients had remnant disc fragments on XMR, which were removed during the same procedure. All of these patients had either highly migrated or sequestrated disc fragments preoperatively. Four (4.49%) other patients needed a second, open surgery due to symptomatic postoperative hematoma (n = 2) and recurrent disc
Accretion Discs Show Their True Colours
NASA Astrophysics Data System (ADS)
Quasars are the brilliant cores of remote galaxies, at the hearts of which lie supermassive black holes that can generate enough power to outshine the Sun a trillion times. These mighty power sources are fuelled by interstellar gas, thought to be sucked into the hole from a surrounding 'accretion disc'. A paper in this week's issue of the journal Nature, partly based on observations collected with ESO's Very Large Telescope, verifies a long-standing prediction about the intensely luminous radiation emitted by these accretion discs. Uncovering the disc ESO PR Photo 21/08 Uncovering the inner disc "Astronomers were puzzled by the fact that the best models of these discs couldn't quite be reconciled with some of the observations, in particular, with the fact that these discs did not appear as blue as they should be," explains lead-author Makoto Kishimoto. Such a discrepancy could be the signal that there was something very wrong with the models. With his colleagues, he investigated this discrepancy by studying the polarised light from six quasars. This enabled them to demonstrate that the disc spectrum is as blue as predicted. "The crucial observational difficulty here has been that the disc is surrounded by a much larger torus containing hot dust, whose light partly outshines that of the disc," says Kishimoto. "Because the light coming from the disc is scattered in the disc vicinity and thus polarised, by observing only polarised light from the quasars, one can uncover the buried light from the disc." In a similar way that a fisherman would wear polarised sunglasses to help get rid of the glare from the water surface and allow him to see more clearly under the water, the filter on the telescope allowed the astronomers to see beyond surrounding clouds of dust and gas to the blue colour of the disc in infrared light. The observations were done with the FORS and ISAAC instruments on one of the 8.2-m Unit Telescopes of ESO's Very Large Telescope, located in the Atacama
On the evolution of the protolunar disc.
Ward, William R
The structure and viscous evolution of a post-impact, protolunar disc is examined. The equations for a silicate disc in two-phase (vapour-liquid) equilibrium are employed to derive an analytical solution to vertical structure. Both a vertically mixed phase disc and a stratified disc, where a magma layer exists in the mid-plane surrounded by a vapour reservoir, are considered. The former largely reproduces the low gas mass fraction, x≪1, profiles of the disc described in earlier literature that proposed that the disc would hover on the brink of gravitational instability. In the latter, the vapour layer has x∼1 and is generally gravitationally stable, while the magma layer is vigorously unstable. The viscous evolution of the stratified model is then explored. Initially, the disc quickly settles to a quasi-steady state with a vapour reservoir containing the majority of the disc mass. The magma layer viscously spreads on a time scale of approximately 3-4 years, during which vapour continuously condenses into droplets that settle to the mid-plane, maintaining the magma surface density in spite of disc spreading. Material flowing inwards is accreted by the Earth; material flowing outwards past the Roche boundary can become incorporated into accreting moonlets. This evolution persists until the vapour reservoir is depleted in approximately 50-100 years, depending on its initial mass. PMID:25114314
The quiescent phase of galactic disc growth
NASA Astrophysics Data System (ADS)
Aumer, Michael; Binney, James; Schönrich, Ralph
We perform a series of controlled N-body simulations of growing disc galaxies within non-growing, live dark matter haloes of varying mass and concentration. Our initial conditions include either a low-mass disc or a compact bulge. New stellar particles are continuously added on near-circular orbits to the existing disc, so spiral structure is continuously excited. To study the effect of combined spiral and giant molecular cloud (GMC) heating on the discs, we introduce massive, short-lived particles that sample a GMC mass function. An isothermal gas component is introduced for a subset of the models. We perform a resolution study and vary parameters governing the GMC population, the histories of star formation and radial scale growth. Models with GMCs and standard values for the disc mass and halo density provide the right level of self-gravity to explain the age-velocity dispersion relation of the solar neighbourhood (Snhd). GMC heating generates remarkably exponential vertical profiles with scaleheights that are radially constant and agree with observations of galactic thin discs. GMCs are also capable of significantly delaying bar formation. The amount of spiral-induced radial migration agrees with what is required for the metallicity distribution of the Snhd. However, in our standard models, the outward-migrating populations are not hot enough vertically to create thick discs. Thick discs can form in models with high baryon fractions, but the corresponding bars are too long, the young stellar populations too hot and the discs flare considerably.
The quiescent phase of galactic disc growth
NASA Astrophysics Data System (ADS)
Aumer, Michael; Binney, James; Schönrich, Ralph
We perform a series of controlled N-body simulations of growing disc galaxies within non-growing, live dark matter haloes of varying mass and concentration. Our initial conditions include either a low-mass disc or a compact bulge. New stellar particles are continuously added on near-circular orbits to the existing disc, so spiral structure is continuously excited. To study the effect of combined spiral and giant molecular cloud (GMC) heating on the discs we introduce massive, short-lived particles that sample a GMC mass function. An isothermal gas component is introduced for a subset of the models. We perform a resolution study and vary parameters governing the GMC population, the histories of star formation and radial scale growth. Models with GMCs and standard values for the disc mass and halo density provide the right level of self-gravity to explain the age velocity dispersion relation of the Solar neighbourhood (Snhd). GMC heating generates remarkably exponential vertical profiles with scaleheights that are radially constant and agree with observations of galactic thin discs. GMCs are also capable of significantly delaying bar formation. The amount of spiral induced radial migration agrees with what is required for the metallicity distribution of the Snhd. However, in our standard models the outward migrating populations are not hot enough vertically to create thick discs. Thick discs can form in models with high baryon fractions, but the corresponding bars are too long, the young stellar populations too hot and the discs flare considerably.
Use of adipose stem cells and polylactide discs for tissue engineering of the temporomandibular joint disc
Mäenpää, Katja; Ellä, Ville; Mauno, Jari; Kellomäki, Minna; Suuronen, Riitta; Ylikomi, Timo; Miettinen, Susanna
There is currently no suitable replacement for damaged temporomandibular joint (TMJ) discs after discectomy. In the present study, we fabricated bilayer biodegradable polylactide (PLA) discs comprising a non-woven mat of poly(L/D)lactide (P(L/D)LA) 96/4 and a P(L/DL)LA 70/30 membrane plate. The PLA disc was examined in combination with adipose stem cells (ASCs) for tissue engineering of the fibrocartilaginous TMJ disc in vitro. ASCs were cultured in parallel in control and chondrogenic medium for a maximum of six weeks. Relative expression of the genes, aggrecan, type I collagen and type II collagen present in the TMJ disc extracellular matrix increased in the ASC-seeded PLA discs in the chondrogenic medium. The hypertrophic marker, type X collagen, was moderately induced. Alcian blue staining showed accumulation of sulphated glycosaminoglycans. ASC differentiation in the PLA discs was close to that observed in pellet cultures. Comparison of the mRNA levels revealed that the degree of ASC differentiation was lower than that in TMJ disc-derived cells and tissue. The pellet format supported the phenotype of the TMJ disc-derived cells under chondrogenic conditions and also enhanced their hyalinization potential, which is considered part of the TMJ disc degeneration process. Accordingly, the combination of ASCs and PLA discs has potential for the development of a tissue-engineered TMJ disc replacement. PMID:19474082
Total Disc Arthroplasty for Treating Lumbar Degenerative Disc Disease
Study Design Lumber disc arthroplasty is a technological advancement that has occurred in the last decade to treat lumbar degenerative disk diseases. Purpose The aim of this retrospective study was to establish the impact and outcomes of managing patients with lumbar degenerative disk disease who have been treated with lumbar total disc arthroplasty (TDA). Overview of Literature Several studies have shown promising results following this surgery. Methods We reviewed the files of 104 patients at the Department of Neurosurgery in Colmar (France) who had been operated on by lumbar spine arthroplasty (Prodisc) between April 2002 and October 2008. Results Among the 104 patients, 67 were female and 37 were male with an average age of 33.1 years. We followed the cases for a mean of 20 months. The most frequent level of discopathy was L4-L5 with 62 patients (59.6%) followed by L5-S1 level with 52 patients (50%). Eighty-three patients suffered from low back pain, 21 of which were associated with radiculopathy. The status of 82 patients improved after surgery according to the Oswestry Disability Index score, and 92 patients returned to work. Conclusions The results indicate that TDA is a good alternative treatment for lumbar spine disk disease, particularly for patients with disabling and chronic low back pain. This technique contributes to improve living conditions with correct patient selection for surgery. PMID:25705336
Total Disc Replacement in Lumbar Degenerative Disc Diseases
More than 10 years have passed since lumbar total disc replacement (LTDR) was introduced for the first time to the world market for the surgical management of lumbar degenerative disc disease (DDD). It seems like the right time to sum up the relevant results in order to understand where LTDR stands on now, and is heading forward to. The pathogenesis of DDD has been currently settled, but diagnosis and managements are still controversial. Fusion is recognized as golden standard of surgical managements but has various kinds of shortcomings. Lately, LTDR has been expected to replace fusion surgery. A great deal of LTDR reports has come out. Among them, more than 5-year follow-up prospective randomized controlled studies including USA IDE trials were expected to elucidate whether for LTDR to have therapeutic benefit compared to fusion. The results of these studies revealed that LTDR was not inferior to fusion. Most of clinical studies dealing with LTDR revealed that there was no strong evidence for preventive effect of LTDR against symptomatic degenerative changes of adjacent segment disease. LTDR does not have shortcomings associated with fusion. However, it has a potentiality of the new complications to occur, which surgeons have never experienced in fusion surgeries. Consequently, longer follow-up should be necessary as yet to confirm the maintenance of improved surgical outcome and to observe any very late complications. LTDR still may get a chance to establish itself as a substitute of fusion both nominally and virtually if it eases the concerns listed above. PMID:26713139
Promising Rapid Access High-Capacity Mass Storage Technique For Diagnostic Information Utilizing Optical Disc
NASA Astrophysics Data System (ADS)
Colby, R. L.; Bartuska, A. J.; Herzog, D. G.
The optical disc has become a new technique for mass digital data storage of X-ray images from examinations and films in todays hospitals. Up to 36,000 X-ray images can be stored on one side of a 12-inch disc by melting holes 0.015 mils in size in an ablative material such as tellerium with a laser beam. This unique characteristic makes the disc suitable for storage and retrieval of X-rays in a record and playback system in either a single disc or multiple disc "jukebox" configuration. Doctors, nurses, technicians and other hospital personnel can call up a particular X-ray in less than 0.6 of a second in an on-line single disc system and up to less than 6 seconds in an on-line "jukebox" system. The jukebox is configured to hold up to 100 discs, thus storing 3,600,000 X-rays in hospitals with a bed size of greater than 500. The estimated exposed films on file in those hospitals is 327,400,000 and the estimated annual X-ray exams are 44,300. Thus, a single disc system could be used for an all electronic X-ray scanning system for annual X-ray exams. The jukebox configuration, which has expansion capability for servicing multiple simultaneous user request, can be applied to large archival mass storage. These systems could store the existing exposed films in hospitals with bed size greater than 500 at record and playback data rates of 50 Mb/s with access times of less than 15 seconds.
Pharmacological mydriasis and optic disc examination
Kirwan, J.; Gouws, P.; Linnell, A.; Crowston, J.; Bunce, C.
AIM—To determine whether pharmacological mydriasis leads to a significant difference in interobserver agreement of optic disc measurement compared with examination without mydriasis. METHOD—A cross sectional study was performed with a pair of observers examining the optic disc of two randomised groups of patients, one group before diagnostic mydriasis, and the other afterwards. Horizontal and vertical disc diameters and cup/disc ratios were measured with a 78 dioptre lens. The study was repeated with another observer pair and two further groups of patients. RESULTS—In study A 86 subjects were examined in total (52 without and 34 with mydriasis). In study B 87 subjects were examined (45 without and 42 with mydriasis). The 95% limits of agreement of the cup/disc ratio measurement differences were significantly larger without mydriasis (p<0.001 for all studies (F test)). For both studies examination after mydriasis gave significantly greater agreement for vertical and horizontal cup/disc ratios. The cases with good agreement (0.1 difference or better) for vertical cup/disc ratios were 37/52 (72%) and 34 /45 (76%) without mydriasis and 33/34 (97%) and 40/42 (95%) respectively with mydriasis. Similar differences were recorded for horizontal cup/disc ratios. Disc diameter measurement results showed similar differences in study A but were not affected by mydriasis in study B. CONCLUSIONS—Examination of the optic disc without pharmacological mydriasis gives significantly poorer interobserver agreement. In this study, the mean 95% limits of agreement values for all cup/disc ratio values were 0.27 for examination without mydriasis and 0.13 for examination with mydriasis. A measure outside these limits would suggest a real difference. This study indicates that mydriasis is important for reproducible clinical examination in glaucoma. PMID:10906099
Quantitative Pfirrmann Disc Degeneration Grading System to Overcome the Limitation of Pfirrmann Disc Degeneration Grade
Objective Pfirrmann disc degeneration grade is one of morphologic disc degeneration grading system and it was reliable on routine T2-weighted magnetic resonance (MR) images. The purpose of this study was to evaluate the agreement of Pfirrmann disc degeneration grade, and check the alternative technique of disc degeneration grading system. Methods Fifteen volunteers (4 medical doctors related to spinal disease, 2 medical doctors not related to spinal disease, 6 nurses in spinal hospital, and 3 para-medicines) were included in this study. Three different digitalized MR images were provided all volunteers, and they checked Pfirrmann disc degeneration grade of each disc levels after careful listening to explanation. Indeed, all volunteers checked the signal intensity of disc degeneration at the points of nucleus pulposus (NP), disc membrane, ligaments, fat, and air to modify the quantitative Pfirrmann disc degeneration grade. Results Total 225 grade results of Pfirrmann disc degeneration grade and 405 signal intensity results of quantitative Pfirrmann disc degeneration grade were analyzed. Average interobserver agreement was "moderate (mean±standard deviation, 0.575±0.251)" from poor to excellent. Completely agreed levels of Pfirrmann disc degeneration grade were only 4 levels (26.67%), and the disagreement levels were observed in 11 levels; two different grades in 8 levels (53.33%) and three different grades in 3 levels (20%). Quantitative Pfirrmann disc degeneration showed relatively cluster distribution with the interobserver deviations of 0.41-1.56 at the ratio of NP and disc membrane, and it showed relatively good cluster and distribution indicating that the proposed grading system has good discrimination ability. Conclusion Pfirrmann disc degeneration grade showed the limitation of different interobserver results, but this limitation could be overcome by using quantitative techniques of MR signal intensity. Further evaluation is needed to access its advantage
Percutaneous Tumor Ablation with Radiofrequency
Wood, Bradford J.; Ramkaransingh, Jeffrey R.; Fojo, Tito; Walther, McClellan M.; Libutti, Stephen K.
BACKGROUND Radiofrequency thermal ablation (RFA) is a new minimally invasive treatment for localized cancer. Minimally invasive surgical options require less resources, time, recovery, and cost, and often offer reduced morbidity and mortality, compared with more invasive methods. To be useful, image-guided, minimally invasive, local treatments will have to meet those expectations without sacrificing efficacy. METHODS Image-guided, local cancer treatment relies on the assumption that local disease control may improve survival. Recent developments in ablative techniques are being applied to patients with inoperable, small, or solitary liver tumors, recurrent metachronous hereditary renal cell carcinoma, and neoplasms in the bone, lung, breast, and adrenal gland. RESULTS Recent refinements in ablation technology enable large tumor volumes to be treated with image-guided needle placement, either percutaneously, laparoscopically, or with open surgery. Local disease control potentially could result in improved survival, or enhanced operability. CONCLUSIONS Consensus indications in oncology are ill-defined, despite widespread proliferation of the technology. A brief review is presented of the current status of image-guided tumor ablation therapy. More rigorous scientific review, long-term follow-up, and randomized prospective trials are needed to help define the role of RFA in oncology. PMID:11900230
Neurologic Complications in Percutaneous Nephrolithotomy
Basiri, Abbas; Soltani, Mohammad Hossein; Kamranmanesh, Mohammadreza; Tabibi, Ali; Mohsen Ziaee, Seyed Amir; Nouralizadeh, Akbar; Sharifiaghdas, Farzaneh; Poorzamani, Mahtab; Gharaei, Babak; Ozhand, Ardalan; Lashay, Alireza; Ahanian, Ali; Aminsharifi, Alireza; Sichani, Mehrdad Mohammadi; Asl-Zare, Mohammad; Ali Beigi, Faramarz Mohammad; Najjaran, Vahid; Abedinzadeh, Mehdi
Purpose Percutaneous nephrolithotomy (PCNL) has been the preferred procedure for the removal of large renal stones in Iran since 1990. Recently, we encountered a series of devastating neurologic complications during PCNL, including paraplegia and hemiplegia. There are several reports of neurologic complications following PCNL owing to paradoxical air emboli, but there are no reports of paraplegia following PCNL. Materials and Methods We retrospectively reviewed the medical records of patients who had undergone PCNL in 13 different endourologic centers and retrieved data related to neurologic complications after PCNL, including coma, paraplegia, hemiplegia, and quadriplegia. Results The total number of PCNL procedures in these 13 centers was 30,666. Among these procedures, 11 cases were complicated by neurologic events, and four of these cases experienced paraplegia. All events happened with the patient in the prone position with the use of general anesthesia and in the presence of air injection. There were no reports of neurologic complications in PCNL procedures performed with the patient under general anesthesia and in the prone position and with contrast injection. Conclusions It can be assumed that using room air to opacify the collecting system played a major role in the occurrence of these complications. Likewise, the prone position and general anesthesia may predispose to these events in the presence of air injection. PMID:23526482
[Permanent percutaneous electric connection. General principles].
Sabin, P; Labbé, D; Levillain, D; Cazin, L; Caston, J
The Swedes for more than twenty years, and the Germans for over five years have been able to maintain inert or active prostheses with permanent percutaneous connections, thanks to the dependable and proven material and techniques of extraoral implants. The significant improvement extra-oral implants have brought about is not only in a new therapeutic approach to the treatment of important facial defects or transmission deafness; it is also because for some twenty old years now, the few millimeter wide cylinders of Titanium, the
Use NASA GES DISC Data in ArcGIS
NASA Technical Reports Server (NTRS)
Yang, Wenli; Pham, Long B.; Kempler, Steve
This presentation describes GIS relevant data at NASA Goddard Earth Sciences Data and Information Services Center (GES DISC), GES DISC Services and Support for GIS Users, and use cases of GES DISC data in ArcGIS.
21 CFR 870.1310 - Vessel dilator for percutaneous catheterization.
Code of Federal Regulations, 2010 CFR
... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Vessel dilator for percutaneous catheterization... Vessel dilator for percutaneous catheterization. (a) Identification. A vessel dilator for percutaneous catheterization is a device which is placed over the guide wire to enlarge the opening in the vessel, and which...
Cervical arthroplasty using ProDisc-C case report.
Nica, D A; Copaciu, R
Cervical disc replacement is an emerging motion-preserving technology in the surgical treatment of the cervical degenerative disc disorders used as an alternative to the classic interbody fusion. We present a case report of a patient diagnosed with C6-7 right disc herniation who underwent anterior discectomy and received a total disc replacement using ProDisc C artificial disc prosthesis. PMID:23599830
Rapid radiative clearing of protoplanetary discs
NASA Astrophysics Data System (ADS)
Haworth, Thomas J.; Clarke, Cathie J.; Owen, James E.
The lack of observed transition discs with inner gas holes of radii greater than ˜50 au implies that protoplanetary discs dispersed from the inside out must remove gas from the outer regions rapidly. We investigate the role of photoevaporation in the final clearing of gas from low mass discs with inner holes. In particular, we study the so-called `thermal sweeping' mechanism which results in rapid clearing of the disc. Thermal sweeping was originally thought to arise when the radial and vertical pressure scalelengths at the X-ray heated inner edge of the disc match. We demonstrate that this criterion is not fundamental. Rather, thermal sweeping occurs when the pressure maximum at the inner edge of the dust heated disc falls below the maximum possible pressure of X-ray heated gas (which depends on the local X-ray flux). We derive new critical peak volume and surface density estimates for rapid radiative clearing which, in general, result in rapid dispersal happening less readily than in previous estimates. This less efficient clearing of discs by X-ray driven thermal sweeping leaves open the issue of what mechanism (e.g. far-ultraviolet heating) can clear gas from the outer disc sufficiently quickly to explain the non-detection of cold gas around weak line T Tauri stars.
The inner cavity of the circumnuclear disc
NASA Astrophysics Data System (ADS)
Blank, M.; Morris, M. R.; Frank, A.; Carroll-Nellenback, J. J.; Duschl, W. J.
The circumnuclear disc (CND) orbiting the Galaxy's central black hole is a reservoir of material that can ultimately provide energy through accretion, or form stars in the presence of the black hole, as evidenced by the stellar cluster that is presently located at the CND's centre. In this paper, we report the results of a computational study of the dynamics of the CND. The results lead us to question two paradigms that are prevalent in previous research on the Galactic Centre. The first is that the disc's inner cavity is maintained by the interaction of the central stellar cluster's strong winds with the disc's inner rim, and secondly, that the presence of unstable clumps in the disc implies that the CND is a transient feature. Our simulations show that, in the absence of a magnetic field, the interaction of the wind with the inner disc rim actually leads to a filling of the inner cavity within a few orbital time-scales, contrary to previous expectations. However, including the effects of magnetic fields stabilizes the inner disc rim against rapid inward migration. Furthermore, this interaction causes instabilities that continuously create clumps that are individually unstable against tidal shearing. Thus the occurrence of such unstable clumps does not necessarily mean that the disc is itself a transient phenomenon. The next steps in this investigation are to explore the effect of the magnetorotational instability on the disc evolution and to test whether the results presented here persist for longer time-scales than those considered here.
D-Zero Cryostat Supplemental Rupture Disc
Mulholland, G.T.; /Fermilab
The common relief and rupture disc vent line requires a double disc assembly with vented interspace for accurate disc burst pressures. The first disc must take pump and purge vacuum loading, but be set to operate at 110% of the MAWP, 18.3 psig (ASME code). The available solution is 18.3 psig with a burst tolerance of +/- psig. The interspace should be locally vented by a flow limiting vent valve to decouple the vent line backpressure from the vessel rupture disc. The second disc must take the worst case vent line backpressure, the steady state value found in D-Zero engineering note 3740.000-EN-63 with all three cryostats simultaneously venting at the fire condition into the 4-inch x 6-inch and 6-inch x 8-inch sections. This value is less than 2 psid. The maximum rupture value for the second disc must be less than the minimum rupture value for the first disc less 2 psid i.e. < 16.3.
Floquet analysis in accretion disc dynamics
NASA Astrophysics Data System (ADS)
Tamburini, F.; Bianchini, A.
Floquet analysis is proposed to analyze the evolution of exponentially growing modes of the local instabilities in accretion discs of CVs induced by perturbations in the velocity field. Both the stability of the disc and the deviation of the Reynolds number are described by the Floquet exponents μj of the perturbations, which represent Landau's modes of the fluid.
Code of Federal Regulations, 2014 CFR
... 46 Shipping 2 2014-10-01 2014-10-01 false Rupture disc. 64.61 Section 64.61 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING MARINE PORTABLE TANKS AND CARGO HANDLING SYSTEMS Pressure Relief Devices and Vacuum Relief Devices for MPTs § 64.61 Rupture disc. If a rupture...
Code of Federal Regulations, 2013 CFR
... 46 Shipping 2 2013-10-01 2013-10-01 false Rupture disc. 64.61 Section 64.61 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING MARINE PORTABLE TANKS AND CARGO HANDLING SYSTEMS Pressure Relief Devices and Vacuum Relief Devices for MPTs § 64.61 Rupture disc. If a rupture...
Code of Federal Regulations, 2011 CFR
... 46 Shipping 2 2011-10-01 2011-10-01 false Rupture disc. 64.61 Section 64.61 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING MARINE PORTABLE TANKS AND CARGO HANDLING SYSTEMS Pressure Relief Devices and Vacuum Relief Devices for MPTs § 64.61 Rupture disc. If a rupture...
Code of Federal Regulations, 2010 CFR
... 46 Shipping 2 2010-10-01 2010-10-01 false Rupture disc. 64.61 Section 64.61 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING MARINE PORTABLE TANKS AND CARGO HANDLING SYSTEMS Pressure Relief Devices and Vacuum Relief Devices for MPTs § 64.61 Rupture disc. If a rupture...
Code of Federal Regulations, 2012 CFR
... 46 Shipping 2 2012-10-01 2012-10-01 false Rupture disc. 64.61 Section 64.61 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING MARINE PORTABLE TANKS AND CARGO HANDLING SYSTEMS Pressure Relief Devices and Vacuum Relief Devices for MPTs § 64.61 Rupture disc. If a rupture...
Disc cell senescence in intervertebral disc degeneration: Causes and molecular pathways
Feng, Chencheng; Liu, Huan; Yang, Minghui; Zhang, Yang; Huang, Bo; Zhou, Yue
ABSTRACT The accumulation of senescent disc cells in degenerative intervertebral disc (IVD) suggests the detrimental roles of cell senescence in the pathogenesis of intervertebral disc degeneration (IDD). Disc cell senescence decreased the number of functional cells in IVD. Moreover, the senescent disc cells were supposed to accelerate the process of IDD via their aberrant paracrine effects by which senescent cells cause the senescence of neighboring cells and enhance the matrix catabolism and inflammation in IVD. Thus, anti-senescence has been proposed as a novel therapeutic target for IDD. However, the development of anti-senescence therapy is based on our understanding of the molecular mechanism of disc cell senescence. In this review, we focused on the molecular mechanism of disc cell senescence, including the causes and various molecular pathways. We found that, during the process of IDD, age-related damages together with degenerative external stimuli activated both p53-p21-Rb and p16-Rb pathways to induce disc cell senescence. Meanwhile, disc cell senescence was regulated by multiple signaling pathways, suggesting the complex regulating network of disc cell senescence. To understand the mechanism of disc cell senescence better contributes to developing the anti-senescence-based therapies for IDD. PMID:27192096
The Survey of the Patient Received the Epiduroscopic Laser Neural Decompression
Jo, Dae Hyun
Background Neuroplasty using a Racz catheter or epiduroscope and percutaneous endoscopic laser discectomy are performed as treatment for chronic refractory low back and/or lower extremity pain, but they are limited in that they cannot completely remove the causing pathology. Lately, epiduroscopic laser neural decompression (ELND) has been receiving attention as an alternative treatment, but there are insufficient reports of results. Hence we aimed to investigate and report the data in our hospital. Methods Seventy-seven patients were selected who had received ELND via the anterior and posterior epidural approach through the pain clinic in our hospital from March 2011 to July 2012. Their medical records including age, diagnosis, epiduroscopic findings and degree of symptom relief were investigated. The degree of symptom relief following the procedure was categorized into 5 stages of very good (5), good (4), no change (3), bad (2), and very bad (1) at 2 weeks and 1 month after the procedure. Results The subjects were 30 males and 47 females. Mean age was 54.6 for males and 59.6 for females, so the overall mean age was 58.1 years old, with the youngest being 23 and the oldest 88 years old. In epiduroscopic images of all patients, more than one situation of herniated disc, fibrous tissue and adhesion, or inflammation was observed. Sixty-seven patients (87.0%) showed symptom relief 2 weeks after the procedure and 63 patients (81.8%) showed relief after 1 month. Conclusions ELND is considered to be an effective treatment alternative for chronic refractory low back and/or lower extremity pain, including lumbar disc herniation, lumbar spinal stenosis, and failed back surgery syndrome which cannot be alleviated with existing non-invasive conservative treatment. PMID:23342204
Simulations of the Galactic Centre Stellar Discs In a Warped Disc Origin Scenario
NASA Astrophysics Data System (ADS)
Ulubay-Siddiki, A.; Bartko, H.
The Galactic Center (GC) hosts a population of young stars some of which seem to form a system of mutually inclined warped discs. While the presence of young stars in the close vicinity of the massive black hole is already problematic, their orbital configuration makes the situation even more puzzling. We present a possible warped disc origin scenario for these stars, which assumes an initially flat accretion disc which develops a warp through Pringle instability, or Bardeen-Petterson Effect. By working out the critical radii and the time scales involved, we argue that disc warping is plausible for GC parameters. We construct time evolution models for such discs considering the discs' self-gravity, and the torques exerted by the surrounding old star cluster. Our simulations suggest that the best agreement for a purely self-gravitating model is obtained for a disc-to-black hole mass ratio of Md/Mbh ~ 0.001.
Dependence of optic disc parameters on disc area according to Heidelberg Retina Tomograph: Part II.
NASA Astrophysics Data System (ADS)
Machekhin, V.; Manaenkova, G.; Bondarenko, O.
With the help of Heidelberg Retina Tomograph (HRT-II) optic disc parameters in 211 eyes of 115 healthy patients with refraction Em +/- 3,0 D and 96 eyes of 72 patients with myopia 3,5-14,0 D without any signs of glaucoma were studied. Analysis of optic disc parameters were carried out in 5 groups of patients according to disc area: less than 1,5 mm2, 1,5- 2,5 mm2, 2,5-3,0 mm2, 3,0-3,5 mm2 and more than 3,5 mm2. An accurate depending on disc area was revealed for all optic disc parameters in all sectors, which was manifested by increasing cup disc and rim disc (area and volume) and other parameters. We consider it is necessary to use the proper tables for right interpretation of received data for early diagnosis of glaucoma.
Ultrasound-guided percutaneous breast biopsy.
Newell, Mary S; Mahoney, Mary C
Ultrasound-guided percutaneous tissue sampling of the breast has positively altered the management of breast lesions, both benign and malignant, since its inception in the 1980s and subsequent widespread acceptance in the 1990s. Its safety, accuracy, and cost-effectiveness have been validated in several studies. However, percutaneous biopsy serves a patient best when performed by an operator with full awareness of patient׳s salient imaging findings; a knowledge of the benefits, limitations, and technical requirements of breast ultrasound; and a thorough understanding of what constitutes an adequate and concordant pathologic specimen. This article outlines a general approach to ultrasound (US)-guided percutaneous breast biopsy and discusses indications, potential complications, and technical aspects of the procedure. PMID:24636328
Percutaneous cholecystostomy in critically ill patients.
Teplick, S K; Harshfield, D L; Brandon, J C; Broadwater, J R; Cone, J B
Sixteen critically ill patients underwent percutaneous cholecystostomy because of suspected acute cholecystitis. The procedure was technically successful, although 11 of 16 patients died subsequently because of various complications of their underlying primary disorders. We reviewed this series to reassess the value of percutaneous cholecystostomy. Four of 11 patients with definite acute cholecystitis (group 1) were cured by this technique, but three required surgery because of gallbladder wall necrosis. Two of these were among four cases which had demonstrated pericholecystic fluid collections on computed tomography (CT) or ultrasound of the abdomen. There were also five patients (group 2) in whom acute cholecystitis or its relationship to patients' symptoms were not fully determined, and four of them did not improve after percutaneous cholecystostomy. We conclude that this technique has a lower success rate in critically ill patients than reported previously. PMID:2016030
About detection of precessing circumpulsar discs
NASA Astrophysics Data System (ADS)
Grimani, Catia
Detections of circumpulsar discs and planetary systems through electromagnetic observations appear quite rare. In the case of PSR 1931+24 and B0656+14, the hypothesis of a precessing disc penetrating the pulsar light cylinder is found consistent with radio and gamma observations from these stars. Disc self-occultation and precession may affect electromagnetic measurements. We investigate here under which conditions gravitational waves generated by circumpulsar disc precession may be detected by the proposed second-generation space interferometers DECI-hertz Interferometer Gravitational Wave Observatory and Big Bang Observer. The characteristics of circumpulsar detectable precessing discs are estimated as a function of distance from the Solar system. Speculations on detection rates are presented.
Hydrodynamic instability in warped astrophysical discs
NASA Astrophysics Data System (ADS)
Ogilvie, Gordon I.; Latter, Henrik N.
Warped astrophysical discs are usually treated as laminar viscous flows, which have anomalous properties when the disc is nearly Keplerian and the viscosity is small: fast horizontal shearing motions and large torques are generated, which cause the warp to evolve rapidly, in some cases at a rate that is inversely proportional to the viscosity. However, these flows are often subject to a linear hydrodynamic instability, which may produce small-scale turbulence and modify the large-scale dynamics of the disc. We use a warped shearing sheet to compute the oscillatory laminar flows in a warped disc and to analyse their linear stability by the Floquet method. We find widespread hydrodynamic instability deriving from the parametric resonance of inertial waves. Even very small, unobservable warps in nearly Keplerian discs of low viscosity can be expected to generate hydrodynamic turbulence, or at least wave activity, by this mechanism.
Strongly magnetized accretion discs require poloidal flux
NASA Astrophysics Data System (ADS)
Salvesen, Greg; Armitage, Philip J.; Simon, Jacob B.; Begelman, Mitchell C.
Motivated by indirect observational evidence for strongly magnetized accretion discs around black holes, and the novel theoretical properties of such solutions, we investigate how a strong magnetization state can develop and persist. To this end, we perform local simulations of accretion discs with an initially purely toroidal magnetic field of equipartition strength. We demonstrate that discs with zero net vertical magnetic flux and realistic boundary conditions cannot sustain a strong toroidal field. However, a magnetic pressure-dominated disc can form from an initial configuration with a sufficient amount of net vertical flux and realistic boundary conditions. Our results suggest that poloidal flux is a necessary prerequisite for the sustainability of strongly magnetized accretion discs.
Lumbar Epidural Varix Mimicking Disc Herniation
Bursalı, Adem; Guvenal, Ahmet Burak; Yaman, Onur
Lumbar radiculopathy is generally caused by such well-recognized entity as lumbar disc herniation in neurosurgical practice; however rare pathologies such as thrombosed epidural varix may mimic them by causing radicular symptoms. In this case report, we present a 26-year-old man with the complaint of back and right leg pain who was operated for right L4–5 disc herniation. The lesion interpreted as an extruded disc herniation preoperatively was found to be a thrombosed epidural varix compressing the nerve root preoperatively. The nerve root was decompressed by shrinking the lesion with bipolar thermocoagulation and excision. The patient's complaints disappeared in the postoperative period. Thrombosed lumbar epidural varices may mimic lumbar disc herniations both radiologically and clinically. Therefore, must be kept in mind in the differential diagnosis of lumbar disc herniations. Microsurgical techniques are mandatory for the treatment of these pathologies and decompression with thermocoagulation and excision is an efficient method. PMID:27446525
Lumbar Epidural Varix Mimicking Disc Herniation.
Bursalı, Adem; Akyoldas, Goktug; Guvenal, Ahmet Burak; Yaman, Onur
Lumbar radiculopathy is generally caused by such well-recognized entity as lumbar disc herniation in neurosurgical practice; however rare pathologies such as thrombosed epidural varix may mimic them by causing radicular symptoms. In this case report, we present a 26-year-old man with the complaint of back and right leg pain who was operated for right L4-5 disc herniation. The lesion interpreted as an extruded disc herniation preoperatively was found to be a thrombosed epidural varix compressing the nerve root preoperatively. The nerve root was decompressed by shrinking the lesion with bipolar thermocoagulation and excision. The patient's complaints disappeared in the postoperative period. Thrombosed lumbar epidural varices may mimic lumbar disc herniations both radiologically and clinically. Therefore, must be kept in mind in the differential diagnosis of lumbar disc herniations. Microsurgical techniques are mandatory for the treatment of these pathologies and decompression with thermocoagulation and excision is an efficient method. PMID:27446525
Strongly magnetized accretion discs require poloidal flux
NASA Astrophysics Data System (ADS)
Salvesen, Greg; Armitage, Philip J.; Simon, Jacob B.; Begelman, Mitchell C.
Motivated by indirect observational evidence for strongly magnetized accretion discs around black holes, and the novel theoretical properties of such solutions, we investigate how a strong magnetization state can develop and persist. To this end, we perform local simulations of accretion discs with an initially purely toroidal magnetic field of equipartition strength. We demonstrate that discs with zero net vertical magnetic flux and realistic boundary conditions cannot sustain a strong toroidal field. However, a magnetic pressure-dominated disc can form from an initial configuration with a sufficient amount of net vertical flux and realistic boundary conditions. Our results suggest that poloidal flux is a necessary prerequisite for the sustainability of strongly magnetized accretion discs.
Structure and evolutionary history of DISC1.
Sanchez-Pulido, Luis; Ponting, Chris P
Evolutionary and protein structural analyses can provide functional insights into genes implicated in human psychiatric diseases. Even eukaryotic organisms lacking nervous systems contain homologues of many key signalling molecules of animal neurons implying that human cognition derives, in part, from modifications of ancestral molecules and complexes. One protein whose evolutionary origin is obscure is DISC1 (disrupted in schizophrenia 1) whose gene locus has been associated with many psychiatric conditions including schizophrenia, clinical depression and bipolar disorder. This protein's rapid evolution and its unusual amino acid and α-helix composition have hindered searches for DISC1 homologues in species other than vertebrates. Here, we review the evolution and structure of the DISC1 protein in the light of in-depth sequence analyses. These predict DISC1 orthologues in diverse eukaryotic organisms, including early-branching animals such as amphioxus, sea anemone, amoebas and Trichoplax, and in plants and algae. DISC1 thus is widespread among eukaryotes, although it remains absent from fungi, nematodes and Diptera, including fruit flies. These observations now permit studies of DISC1 function in simple non-vertebrate model organisms. Surprisingly, these analyses also identify between two and four sequence repeats in DISC1 orthologues. The first two of these repeats show significant sequence similarity to the UVR family of globular domains. These UVR-like repeats are predicted to contain, not coiled coil structures, but rather two closely associated antiparallel α-helices. One common missense variant in DISC1 (L607F) lies within the second DISC1 UVR-like domain. These observations should assist in delineating the functional regions of the DISC1 protein. PMID:21852244
Percutaneous Pediatric Foot and Ankle Surgery.
Uglow, Michael G
The techniques for performing percutaneous osteotomies in treating deformities of the foot in children are presented along with a detailed description of the operative details. The author's use of minimal-access surgery for tibial, os calcis, and midfoot osteotomies is described using a cooled side-cutting burr that has not previously been described for use in the child's foot. The cancellous nature of the bones in the child are easily cut with the burr and the adjacent soft tissues are not damaged. The early experience of the healing times are not impaired and the complications associated with percutaneous scars seem to be negligible. PMID:27524707
Percutaneous Cryotherapy of Vascular Malformation: Initial Experience
Cornelis, F.; Neuville, A.; Labreze, C.; Kind, M.; Bui, B.; Midy, D.; Palussiere, J.; Grenier, N.
The present report describes a case of percutaneous cryotherapy in a 36-year-old woman with a large and painful pectoral venous malformation. Cryoablation was performed in a single session for this 9-cm mass with 24 h hospitalisation. At 2- and 6-month follow-up, the pain had completely disappeared, and magnetic resonance imaging demonstrated a significant decrease in size. Percutaneous cryoablation shows promise as a feasible and apparently safe method for local control in patients with symptomatic venous vascular malformations.
Renal effects of percutaneous stone removal
Eshghi, M.; Schiff, R.G.; Smith, A.D.
Preoperative and postoperative renography with 99mTechnetium-diethylene-triamine pentaacetic acid was performed on 33 patients who were free of renal scarring, infection, and obstruction and who underwent percutaneous renal stone removal. Although there was a transient decrease in renal function postoperatively in some patients, statistically significant reductions in renal function occurred only in 1 patient with an arteriovenous malformation that was embolized and in 1 patient who had a postoperative ureteropelvic junction stricture. The creation of more than one nephrostomy tract did not affect the results. In the absence of serious complications, percutaneous nephrostomy does not have a significant effect on renal function.
Update on percutaneous mitral commissurotomy.
Nunes, Maria Carmo P; Nascimento, Bruno Ramos; Lodi-Junqueira, Lucas; Tan, Timothy C; Athayde, Guilherme Rafael Sant'Anna; Hung, Judy
Percutaneous mitral commissurotomy (PMC) is the first-line therapy for managing rheumatic mitral stenosis. Over the past two decades, the indications of the procedure have expanded to include patients with unfavourable valve anatomy as a consequence of epidemiological changes in patient population. The procedure is increasingly being performed in patients with increased age, more deformed valves and associated comorbidities. Echocardiography plays a crucial role in patient selection and to guide a more efficient procedure. The main echocardiographic predictors of immediate results after PMC are mitral valve area, subvalvular thickening and valve calcification, especially at the commissural level. However, procedural success rate is not only dependent on valve anatomy, but a number of other factors including patient characteristics, interventional management strategies and operator expertise. Severe mitral regurgitation continues to be the most common immediate procedural complication with unchanged incidence rates over time. The long-term outcome after PMC is mainly determined by the immediate procedural results. Postprocedural parameters associated with late adverse events include mitral valve area, mitral regurgitation severity, mean gradient and pulmonary artery pressure. Mitral restenosis is an important predictor of event-free survival rates after successful PMC, and repeat procedure can be considered in cases with commissural refusion. PMC can be performed in special situations, which include high-risk patients, during pregnancy and in the presence of left atrial thrombus, especially in centres with specialised expertise. Therefore, procedural decision-making should take into account the several determinant factors of PMC outcomes. This paper provides an overview and update of PMC techniques, complications, immediate and long-term results over time, and assessment of suitability for the procedure. PMID:26743926
Signal processing for 35GB on a single-layer Blu-ray disc
NASA Astrophysics Data System (ADS)
Padiy, Alexander V.; Yin, Bin; Verschuren, Coen A.; Lee, Julian I.; Vlutters, Ruud; Jansen, Theo P.
We report on the technical progress in increasing the recording density of optical storage systems by means of improved read-channel signal processing and write-channel optimisation. The recording density increase is realized by employing PRML (Viterbi) bit detection in combination with improved timing recovery and adaptive equalisation algorithms, and by using a signal quality characterisation scheme which enables a proper control of the write process in the considered range of storage densities. The Blu-ray Disc (BD) optical disc system employing blue-violet laser with the wavelength of 405nm, objective lens with numerical aperture of 0.85 and disc cover layer thickness of 0.1mm is used as an experimental platform in our present study. Multi-track experimental results for both single-layer read-only (BD-ROM) and single-layer rewritable (BD-RE) media are presented to show the feasibility of the increased-density BD.
Biliary pressure: manometric and perfusion studies at percutaneous transhepatic cholangiography and percutaneous biliary drainage
vanSonnenberg, E.; Ferrucci, J.T. Jr.; Neff, C.C.; Mueller, P.R.; Simeone, J.F.; Wittenberg, J.
Manometric pressure recordings were attempted during percutaneous transhepatic cholangiography (PTC) and after percutaneous biliary drainage (PBD) in 203 cases. Successful readings were achieved at PTC in 85% (104/122) of patients. Pressure measurements were also obtained through 56 biliary drainage catheters, and controlled perfusion challenges were performed in 12 patients (on 18 occasions). Documentation of the occasionally poor correlation between the caliber of ducts and the degree of obstruction (i.e., pressure) was shown, and it was suggested that very high pressures may be predictive of a bile leak after PTC. Adequacy of percutaneous drainage and stricture dilatation were further assessed with these manometric techniques. Pressure and perfusion data aided in detecting and determining the significance of the nondilated obstructed duct, the dilated nonobstructed ductal system, and subtle distal ductal strictures. The knowledge obtained from percutaneous pressure recordings may help to determine appropriate therapy.
From the channel model of an InSb-based superresolution optical disc system to impulse response and resolution limits.
Hepper, Dietmar
The signal model of a superresolution optical channel can be an efficient tool for developing components of an associated high-density optical disc system. While the behavior of the laser diode, aperture, lens, and detector are properly described, a general mathematical model of the superresolution disc itself has not yet been available until recently. Different approaches have been made to describe the properties of a mask layer, mainly based on temperature- or power-dependent nonlinear effects. A complete signal-based or phenomenological optical channel model--from non-return-to-zero inverted input to disc readout signal--has recently been developed including the reflectivity of a superresolution disc with InSb used for the mask layer. In this contribution, the model is now extended and applied to a moving disc including a land-and-pit structure, and results are compared with data read from real superresolution discs. Both impulse response and resolution limits are derived and discussed. Thus the model provides a bridge from physical to readout signal properties, which count after all. The presented approach allows judging of the suitability of a mask layer material for storage density enhancement already based on static experiments, i.e., even before developing an associated disc drive. PMID:21673750
Fabrication of read-only type triple-layered disc
NASA Astrophysics Data System (ADS)
Yang, Huei Wen; Jeng, Tzuan Ren; Yen, Wen Hsin; Chan, Rong Po; Shin, Kuo Ding; Huang, Der Ray
The approach to increase optical recording density has become very popular research subject in these years. One direct and effective method is to increase the recording layer stack number. That is to say, to add one more recording layer can get one more recording capacity. In this paper, we will propose a new method for manufacturing read only type multi-layered disc. The process is described in the following. This first recorded data layer (called L0) still follows the traditional DVD disc manufacturing process. We obtain the polycarbonate substrate by replicating from Ni stamper. Then polycarbonate substrate is sputtered thin silicon film for semi-reflection layer. As for second layer (L1) and even more layer (Ln-1) producing, one special kind of duplication (called SKD) method is proposed. The duplication (or replication) source of second or nth recorded data is not only limited from Ni stamper. Even polycarbonate or PMMA substrate has recording data are also acceptable sources. At next step, the duplication source is deposited by thin gold film. Then we apply spin coating to bond the first layer (L0) substrate and second layer (L1) duplication source by choosing suitable UV curing glue. After being emitted by UV lamp for several seconds, we can easily separate the duplication source of second layer (L1) from (L0) substrate. Then we find the thin second data layer (L1) is replicated and stacks upon the first layer. On the same way, we sputter thin AgTi layer on the thin second data layer for another semi- reflective layer. By following the above manufacture step, we can produce more layers. In our experimental, we prepare triple layered read-only type disc. The total capacity is almost 12GB for one side of disc, and 24GB for two side of disc. The read-out intensity of laser from each data layer is expected to be similar. Thus we have designed particular reflectance and transmittance for each data layer by controlling the thickness of thin silicon film. We can
Spontaneous Regression of Herniated Lumbar Disc with New Disc Protrusion in the Adjacent Level.
Hakan, Tayfun; Gürcan, Serkan
Spontaneous regression of herniated lumbar discs was reported occasionally. The mechanisms proposed for regression of disc herniation are still incomplete. This paper describes and discusses a case of spontaneous regression of herniated lumbar discs with a new disc protrusion in the adjacent level. A 41-year-old man was admitted with radiating pain and numbness in the left lower extremity with a left posterolateral disc extrusion at L5-S1 level. He was admitted to hospital with low back pain due to disc herniation caudally immigrating at L4-5 level three years ago. He refused the surgical intervention that was offered and was treated conservatively at that time. He had no neurological deficit and a history of spontaneous regression of the extruded lumbar disc; so, a conservative therapy, including bed rest, physical therapy, nonsteroidal anti-inflammatory drugs, and analgesics, was advised. In conclusion, herniated lumbar disc fragments may regress spontaneously. Reports are prone to advise conservative treatment for extruded or sequestrated lumbar disc herniations. However, these patients should be followed up closely; new herniation at adjacent/different level may occur. Furthermore, it is important to know which herniated disk should be removed and which should be treated conservatively, because disc herniation may cause serious complications as muscle weakness and cauda equine syndrome. PMID:27429818
Spontaneous Regression of Herniated Lumbar Disc with New Disc Protrusion in the Adjacent Level
Gürcan, Serkan
Spontaneous regression of herniated lumbar discs was reported occasionally. The mechanisms proposed for regression of disc herniation are still incomplete. This paper describes and discusses a case of spontaneous regression of herniated lumbar discs with a new disc protrusion in the adjacent level. A 41-year-old man was admitted with radiating pain and numbness in the left lower extremity with a left posterolateral disc extrusion at L5-S1 level. He was admitted to hospital with low back pain due to disc herniation caudally immigrating at L4-5 level three years ago. He refused the surgical intervention that was offered and was treated conservatively at that time. He had no neurological deficit and a history of spontaneous regression of the extruded lumbar disc; so, a conservative therapy, including bed rest, physical therapy, nonsteroidal anti-inflammatory drugs, and analgesics, was advised. In conclusion, herniated lumbar disc fragments may regress spontaneously. Reports are prone to advise conservative treatment for extruded or sequestrated lumbar disc herniations. However, these patients should be followed up closely; new herniation at adjacent/different level may occur. Furthermore, it is important to know which herniated disk should be removed and which should be treated conservatively, because disc herniation may cause serious complications as muscle weakness and cauda equine syndrome. PMID:27429818
Percutaneous Cyanoacrylate Glue Injection into the Renal Pseudoaneurysm to Control Intractable Hematuria After Percutaneous Nephrolithotomy
Lal, Anupam Kumar, Ajay; Prakash, Mahesh; Singhal, Manphool; Agarwal, Mayank Mohan; Sarkar, Debansu; Khandelwal, Niranjan
We report a case of a 43-year-old man who developed intractable hematuria after percutaneous nephrolithotomy. Angiography detected a pseudoaneurysm arising from the lower polar artery; however, embolization could not be performed because of unfavorable vascular anatomy. A percutaneous thrombin injection under ultrasound guidance initially controlled the bleeding, but hematuria subsequently recurred as a result of recanalization of the aneurysm. The case was successfully managed with ultrasound- and fluoroscopic-guided direct injection of cyanoacrylate glue into the pseudoaneurysm.
Stem cells sources for intervertebral disc regeneration
Vadalà, Gianluca; Russo, Fabrizio; Ambrosio, Luca; Loppini, Mattia; Denaro, Vincenzo
Intervertebral disc regeneration field is rapidly growing since disc disorders represent a major health problem in industrialized countries with very few possible treatments. Indeed, current available therapies are symptomatic, and surgical procedures consist in disc removal and spinal fusion, which is not immune to regardable concerns about possible comorbidities, cost-effectiveness, secondary risks and long-lasting outcomes. This review paper aims to share recent advances in stem cell therapy for the treatment of intervertebral disc degeneration. In literature the potential use of different adult stem cells for intervertebral disc regeneration has already been reported. Bone marrow mesenchymal stromal/stem cells, adipose tissue derived stem cells, synovial stem cells, muscle-derived stem cells, olfactory neural stem cells, induced pluripotent stem cells, hematopoietic stem cells, disc stem cells, and embryonic stem cells have been studied for this purpose either in vitro or in vivo. Moreover, several engineered carriers (e.g., hydrogels), characterized by full biocompatibility and prompt biodegradation, have been designed and combined with different stem cell types in order to optimize the local and controlled delivery of cellular substrates in situ. The paper overviews the literature discussing the current status of our knowledge of the different stem cells types used as a cell-based therapy for disc regeneration. PMID:27247704
Stem cells sources for intervertebral disc regeneration.
Vadalà, Gianluca; Russo, Fabrizio; Ambrosio, Luca; Loppini, Mattia; Denaro, Vincenzo
Intervertebral disc regeneration field is rapidly growing since disc disorders represent a major health problem in industrialized countries with very few possible treatments. Indeed, current available therapies are symptomatic, and surgical procedures consist in disc removal and spinal fusion, which is not immune to regardable concerns about possible comorbidities, cost-effectiveness, secondary risks and long-lasting outcomes. This review paper aims to share recent advances in stem cell therapy for the treatment of intervertebral disc degeneration. In literature the potential use of different adult stem cells for intervertebral disc regeneration has already been reported. Bone marrow mesenchymal stromal/stem cells, adipose tissue derived stem cells, synovial stem cells, muscle-derived stem cells, olfactory neural stem cells, induced pluripotent stem cells, hematopoietic stem cells, disc stem cells, and embryonic stem cells have been studied for this purpose either in vitro or in vivo. Moreover, several engineered carriers (e.g., hydrogels), characterized by full biocompatibility and prompt biodegradation, have been designed and combined with different stem cell types in order to optimize the local and controlled delivery of cellular substrates in situ. The paper overviews the literature discussing the current status of our knowledge of the different stem cells types used as a cell-based therapy for disc regeneration. PMID:27247704
Shear Mechanics of the TMJ Disc
Juran, C.M.; Dolwick, M.F.; McFetridge, P.S.
The temporomandibular joint (TMJ) is a complex hinge and gliding joint that induces significant shear loads onto the fibrocartilage TMJ disc during jaw motion. The purpose of this study was to assess regional variation in the disc's shear loading characteristics under physiologically relevant loads and to associate those mechanical findings with common clinical observations of disc fatigue and damage. Porcine TMJ discs were compressed between an axially translating bottom platen and a 2.5-cm-diameter indenter within a hydrated testing chamber. Discs were cyclically sheared at 0.5, 1, or 5 Hz to 1, 3, or 5% shear strain. Within the anterior and intermediate regions of the disc when sheared in the anteroposterior direction, both shear and compressive moduli experienced a significant decrease from instantaneous to steady state, while the posterior region's compressive modulus decreased approximately 5%, and no significant loss of shear modulus was noted. All regions retained their shear modulus within 0.5% of instantaneous values when shear was applied in the mediolateral direction. The results of the disc's regional shear mechanics suggest an observable and predictable link with the common clinical observation that the posterior region of the disc is most often the zone in which fatigue occurs, which may lead to disc damage and perforation. PMID:23166043
33.4 Gbyte/Layer Recording with Adaptive Write Strategy for 100 Gbyte Rewritable Triple-Layer Disc
NASA Astrophysics Data System (ADS)
Nakamura, Atsushi; Kobayashi, Isao; Narumi, Kenji; Takaoka, Tomoyasu; Furumiya, Shigeru; Miyagawa, Naoyasu
For multilayer rewritable optical discs, we developed a new adaptive write strategy named the S-22 (sequential 2T-2T) write pulse control method, which controls the laser pulse of the 2T-mark according to the combination of both the preceding and succeeding space lengths. By applying this write strategy, a rewritable triple-layer disc based on Blu-ray disc optical systems with a capacity of 100 Gbyte was realized. In particular, the advantage of this write strategy is significant for a transparent information layer. The bit shift of sequential 2T-2T patterns, which is a dominant error in 100 Gbyte rewritable discs, was well compensated. We experimentally confirmed that adopting the S-22 write pulse control method is effective to improve symbol error rate.
Comparative evaluation of the three different surface treatments – conventional, laser and Nano technology methods in enhancing the surface characteristics of commercially pure titanium discs and their effects on cell adhesion: An in vitro study
Vignesh; Nayar, Sanjna; Bhuminathan; Mahadevan; Santhosh, S.
The surface area of the titanium dental implant materials can be increased by surface treatments without altering their shape and form, thereby increasing the biologic properties of the biomaterial. A good biomaterial helps in early cell adhesion and cell signaling. In this study, the commercially pure titanium surfaces were prepared to enable machined surfaces to form a control material and to be compared with sandblasted and acid-etched surfaces, laser treated surfaces and titanium dioxide (20 nm) Nano-particle coated surfaces. The surface elements were characterized. The biocompatibility was evaluated by cell culture in vitro using L929 fibroblasts. The results suggested that the titanium dioxide Nano-particle coated surfaces had good osteoconductivity and can be used as a potential method for coating the biomaterial. PMID:26015762
Retrospective Evaluation of Efficiency and Safety of an Anterior Percutaneous Approach for Cervical Discectomy
Schubert, Michael
Study Design Retrospective case series. Purpose The purpose of the study was to evaluate the efficiency and complication rate of a percutaneous anterior approach to herniated cervical disks with or without concomitant foraminal stenosis and/or spondylosis. Overview of Literature Recent publications reflect that minimally invasive procedures gain in importance in patients and spine surgeons as they are generally associated with less tissue damage and shorter recovery times. However, for anterior percutaneous cervical discectomy, very little data is available for relevant patient populations. Methods Charts from patients with herniated cervical disc confirmed by magnetic resonance imaging, mainly radicular symptoms and irresponsive to conservative treatment who underwent anterior percutaneous discectomy were evaluated retrospectively. All patients were asked to return questionnaires that included visual analogue scores (VAS), MacNab score as well as subjective satisfaction data 2 years after surgery. Results Ninety-five patients were included. There were no neurological or vascular complications; only one patient suffered from transient hoarseness. During the two years after surgery, 9 patients underwent reoperation. 90.5% of the patients returned the questionnaire at 2 years' follow-up. 87.7% of them reported excellent or good outcome, 11.1% rated results as fair and 1.2% as unsatisfactory. On average, arm and neck pain improved significantly by 6.1 points and 5.8 points respectively on a ten point VAS. 94.5% stated that they would choose the same procedure again. Conclusions This procedure has proved a safe and sufficient option for symptomatic cervical disk herniations with or without concomitant spondylosis and/or foraminal stenosis. PMID:25187857
Improvements in Intracorporeal Lithotripters for Percutaneous Nephrolithotomy
NASA Astrophysics Data System (ADS)
Kuo, Ramsay L.
Percutaneous nephrolithotomy (PNL) is an effective minimally invasive surgical approach for the treatment of large renal stone burden. Intracorporeal lithotripters (ICL) are utilized during PNL to fragment calculi, with some devices capable of concurrently removing fragments as well. Much progress has been made in the design of ICL devices, resulting in potentially more efficient treatment of nephrolithiasis.
21 CFR 870.1250 - Percutaneous catheter.
Code of Federal Regulations, 2010 CFR
... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Percutaneous catheter. 870.1250 Section 870.1250 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED... through the skin using a dilator and a sheath (introducer) or guide wire. (b) Classification. Class...
Percutaneous Surgery for Severe Hallux Valgus.
Vernois, Joel; Redfern, David J
Severe hallux valgus is a challenge to treat. If the basal osteotomy is a well known surgery for severe deformity, the chevron osteotomy is usually used in mild to moderate deformity. With a accurent fixation the chevron can also be used in severe deformity. Both techniques can be performed percutaneously and offer reliable techniques. PMID:27524702
Electron beam recording of optical disc
NASA Astrophysics Data System (ADS)
Cartwright, Giles; Reynolds, Gerald; Baylis, Chris; Pearce, Adrian; Dix, Colin; Ogilvie, Nick
The Nimbus Technology & Engineering e -Beam Mastering System was developed to gain a large improvement in optical disc and structured hard disc recording capacity, significantly more than is possible from deep UV and SIL mastering. The current electron beam recorder is essentially a production machine capable of making full-length exposures at capacities of up to 50 GB with a simple low-cost upgrade path to disc capacities of several hundred gigabytes and beyond and hard disk drives (HDD) with capacities of up to 1 tera bit per square inch.
[Lumbar disc herniation and andrological diseases].
Jin, Bao-fang
Lumbar disc herniation is a common male disease. In the past, More academic attention was directed to its relationship with lumbago and leg pain than to its association with andrological diseases. Studies show that central lumber intervertebral disc herniation may cause cauda equina injury and result in premature ejaculation, erectile dysfunction, chronic pelvic pain syndrome, priapism, and emission. This article presents an overview on the correlation between central lumbar intervertebral disc herniation and andrological diseases, focusing on the aspects of etiology, pathology, and clinical progress, hoping to invite more attention from andrological and osteological clinicians. PMID:26665671
Spectroscopic Parameters of Lumbar Intervertebral Disc Material
NASA Astrophysics Data System (ADS)
Terbetas, G.; Kozlovskaja, A.; Varanius, D.; Graziene, V.; Vaitkus, J.; Vaitkuviene, A.
There are numerous methods of investigating intervertebral disc. Visualization methods are widely used in clinical practice. Histological, imunohistochemical and biochemical methods are more used in scientific research. We propose that a new spectroscopic investigation would be useful in determining intervertebral disc material, especially when no histological specimens are available. Purpose: to determine spectroscopic parameters of intervertebral disc material; to determine emission spectra common for all intervertebral discs; to create a background for further spectroscopic investigation where no histological specimen will be available. Material and Methods: 20 patients, 68 frozen sections of 20 μm thickness from operatively removed intervertebral disc hernia were excited by Nd:YAG microlaser STA-01-TH third harmonic 355 nm light throw 0, 1 mm fiber. Spectrophotometer OceanOptics USB2000 was used for spectra collection. Mathematical analysis of spectra was performed by ORIGIN multiple Gaussian peaks analysis. Results: In each specimen of disc hernia were found distinct maximal spectral peaks of 4 types supporting the histological evaluation of mixture content of the hernia. Fluorescence in the spectral regions 370-700 nm was detected in the disc hernias. The main spectral component was at 494 nm and the contribution of the components with the peak wavelength values at 388 nm, 412 nm and 435±5 nm were varying in the different groups of samples. In comparison to average spectrum of all cases, there are 4 groups of different spectral signatures in the region 400-500 nm in the patient groups, supporting a clinical data on different clinical features of the patients. Discussion and Conclusion: besides the classical open discectomy, new minimally invasive techniques of treating intervertebral disc emerge (PLDD). Intervertebral disc in these techniques is assessed by needle, no histological specimen is taken. Spectroscopic investigation via fiber optics through the
How Does Lumbar Degenerative Disc Disease Affect the Disc Deformation at the Cephalic Levels In Vivo?
Wang, Shaobai; Xia, Qun; Passias, Peter; Li, Weishi; Wood, Kirkham; Li, Guoan
Study Design Case-control study. Objective . To evaluate the effect of lumbar degenerative disc disease (DDD) on the disc deformation at the adjacent level and at the level one above the adjacent level during end ranges of lumbar motion. Summary of Background Data It has been reported that in patients with DDD, the intervertebral discs adjacent to the diseased levels have a greater tendency to degenerate. Although altered biomechanics have been suggested to be the causative factors, few data have been reported on the deformation characteristics of the adjacent discs in patients with DDD. Methods Ten symptomatic patients with discogenic low back pain between L4 and S1 and with healthy discs at the cephalic segments were involved. Eight healthy subjects recruited in our previous studies were used as a reference comparison. The in vivo kinematics of L3–L4 (the cephalic adjacent level to the degenerated discs) and L2–L3 (the level one above the adjacent level) lumbar discs of both groups were obtained using a combined magnetic resonance imaging and dual fluoroscopic imaging technique at functional postures. Deformation characteristics, in terms of areas of minimal deformation (defined as less than 5%), deformations at the center of the discs, and maximum tensile and shear deformations, were compared between the two groups at the two disc levels. Results In the patients with DDD, there were significantly smaller areas of minimal disc deformation at L3–L4 and L2–L3 than the healthy subjects (18% compared with 45% of the total disc area, on average). Both L2–L3 and L3–L4 discs underwent larger tensile and shear deformations in all postures than the healthy subjects. The maximum tensile deformations were higher by up to 23% (of the local disc height in standing) and the maximum shear deformations were higher by approximately 25% to 40% (of the local disc height in standing) compared with those of the healthy subjects. Conclusion Both the discs of the adjacent
[Ultrasound-guided percutaneous nephrostomy].
Martino, P
Percutaneous nephrostomy is a mini-invasive technique that creates an external outlet from the renal excretory tract through a catheter inserted through the flank. Indications for this procedure are of both diagnostic and therapeutic type. The nephrostomic catheter is generally positioned under ultrasound guidance, which has the advantages of showing the localization of the renal cavities and the depth of the kidney, and can be used during pregnancy and in subjects with allergy to contrast medium or with reduced renal function. When possible, it is best to associate US with fluoroscopic guidance, as this association has been found to guarantee a success rate exceeding 98%. Within the kidney, the zone known as Broedel's avascular plane, where the terminal branches of the posterior and anterior arterial systems meet, is the safest place to pass the nephrostomic catheter through, as there is little vascularization in this zone. Access is generally posterior and at the level of the inferior calyx, by means of Seldinger's, the one step or a mixed access technique involving a catheter sheathing a metal cannula. Seldinger's access technique is most commonly used, entailing explorative puncture of the renal cavity with a 22 G needle. We prefer to puncture the kidney direct, under US guidance and using an 18 G needle: a metal wire is passed through the needle and then after withdrawing the needle, the fascia dilators are inserted, of scaled widths increasing up to 2 G wider than the nephrostomic catheter. Care must be taken not to go beyond the curve of the guide wire to avoid trauma to the renal parenchyma. The most critical moment is when the catheter is inserted along the wire at the point of passage through the peri-renal fat: the catheter tends to deflect the point of the guide wire away from the desired direction as the peri-renal fat offers less resistance. The metal wire may be of variable rigidity and length, hydrophilic. The catheter may also be made of various
Computation of fluid flow and heat transfer in rotating disc-systems
NASA Astrophysics Data System (ADS)
Ong, Chew-Lan
Described here is a numerical investigation into the turbulent flow and heat transfer characteristics in rotating disc systems. Particular emphasis has been given to the study of a rotating cylindrical cavity with a radial outflow of fluid which provides a simple model of the flow between two corotating air-cooled gas-turbine discs. Study is also made of the free disc, a single disc rotating in an infinite quiescent environment. The main effort has been devoted to the development and application of a suite of computer programs for the solution of the momentum and energy equations governing the highly-skewed boundary layers on the discs, for both incompressible and compressible flows. An accurate and efficient solution procedure has been devised, based on the Keller-Box finite-difference scheme, and a noniterative method for the determination of the pressure field implemented. Serious numerical problems associated with the reverse flows in the nonentraining Ekman-type layer have been successfully overcome. Turbulence has been modelled using both isotropic and anisotropic eddy-viscosity/mixing-length formulations, the use of a low-Reynolds-number k-epsilon turbulence model proving unsatisfactory. Predictions of the velocity distributions inside the Ekman layer and in the inviscid core of the rotating cavity have been compared with extensive laser-Doppler-anemometry measurements.
Association between optic nerve blood flow and objective examinations in glaucoma patients with generalized enlargement disc type
Chiba, Naoki; Omodaka, Kazuko; Yokoyama, Yu; Aizawa, Naoko; Tsuda, Satoru; Yasuda, Masayuki; Otomo, Takaaki; Yokokura, Shunji; Fuse, Nobuo; Nakazawa, Toru
Background The purpose of this study was to investigate the correlations between microcirculation in the optic disc, average peripapillary retinal nerve fiber layer thickness cupping parameters, and visual field defects in glaucoma patients with the generalized enlargement disc type. Methods A total of 38 eyes from 38 glaucoma patients with the generalized enlargement disc type were included. The microcirculation of the optic nerve head was examined with laser speckle flow graphy, and the mean blur rate in all areas, in vessel area, and in tissue area were calculated using the laser speckle flow graphy analyzer software. Average peripapillary retinal nerve fiber layer thickness was measured using Stratus optical coherence tomography, and cupping parameters were accessed using the Heidelberg retina tomograph. The mean deviation in the Humphrey field analyzer (30-2 SITA standard) was analyzed. The correlation between these parameters was evaluated using the Spearman rank correlation coefficient. Results The correlation coefficient of mean blur rate in all optic disc area to the average peripapillary retinal nerve fiber layer thickness, vertical C/D, and mean deviation were r = 0.7546 (P < 0.0001), r = −0.6208 (P < 0.0001), and r = 0.6010 (P = 0.0001), respectively. The mean blur rate in tissue area of the optic disc showed r = 0.7305 (P < 0.0001), r = −0.6438 (P < 0.0001), and r = 0.6338 (P < 0.0001). Conclusion We found that the mean blur rate in the optic disc was significantly correlated with the average peripapillary retinal nerve fiber layer thickness, vertical C/D, and mean deviation in patients with the generalized enlargement disc type of glaucoma. In particular, the mean blur rate in tissue area was more highly correlated than the vessel area with other results of examination in glaucoma patients with the generalized enlargement disc type. PMID:22125400
Perk Station – Percutaneous Surgery Training and Performance Measurement Platform
Vikal, Siddharth; U-Thainual, Paweena; Carrino, John A.; Iordachita, Iulian; Fischer, Gregory S.; Fichtinger, Gabor
Motivation Image-guided percutaneous (through the skin) needle-based surgery has become part of routine clinical practice in performing procedures such as biopsies, injections and therapeutic implants. A novice physician typically performs needle interventions under the supervision of a senior physician; a slow and inherently subjective training process that lacks objective, quantitative assessment of the surgical skill and performance[S1]. Shortening the learning curve and increasing procedural consistency are important factors in assuring high-quality medical care. Methods This paper describes a laboratory validation system, called Perk Station, for standardized training and performance measurement under different assistance techniques for needle-based surgical guidance systems. The initial goal of the Perk Station is to assess and compare different techniques: 2D image overlay, biplane laser guide, laser protractor and conventional freehand. The main focus of this manuscript is the planning and guidance software system developed on the 3D Slicer platform, a free, open source software package designed for visualization and analysis of medical image data. Results The prototype Perk Station has been successfully developed, the associated needle insertion phantoms were built, and the graphical user interface was fully implemented. The system was inaugurated in undergraduate teaching and a wide array of outreach activities. Initial results, experiences, ongoing activities and future plans are reported. PMID:19539446
Total Percutaneous Aortic Repair: Midterm Outcomes
Bent, Clare L. Fotiadis, Nikolas; Renfrew, Ian; Walsh, Michael; Brohi, Karim; Kyriakides, Constantinos; Matson, Matthew
The purpose of this study was to examine the immediate and midterm outcomes of percutaneous endovascular repair of thoracic and abdominal aortic pathology. Between December 2003 and June 2005, 21 patients (mean age: 60.4 {+-} 17.1 years; 15 males, 6 females) underwent endovascular stent-graft insertion for thoracic (n = 13) or abdominal aortic (n = 8) pathology. Preprocedural computed tomographic angiography (CTA) was performed to assess the suitability of aorto-iliac and common femoral artery (CFA) anatomy, including the degree of CFA calcification, for total percutaneous aortic stent-graft repair. Percutaneous access was used for the introduction of 18- to 26-Fr delivery devices. A 'preclose' closure technique using two Perclose suture devices (Perclose A-T; Abbott Vascular) was used in all cases. Data were prospectively collected. Each CFA puncture site was assessed via clinical examination and CTA at 1, 6, and 12 months, followed by annual review thereafter. Minimum follow-up was 36 months. Outcome measures evaluated were rates of technical success, conversion to open surgical repair, complications, and late incidence of arterial stenosis at the site of Perclose suture deployment. A total of 58 Perclose devices were used to close 29 femoral arteriotomies. Outer diameters of stent-graft delivery devices used were 18 Fr (n = 5), 20 Fr (n = 3), 22 Fr (n = 4), 24 Fr (n = 15), and 26 Fr (n = 2). Percutaneous closure was successful in 96.6% (28/29) of arteriotomies. Conversion to surgical repair was required at one access site (3.4%). Mean follow-up was 50 {+-} 8 months. No late complications were observed. By CT criteria, no patient developed a >50% reduction in CFA caliber at the site of Perclose deployment during the study period. In conclusion, percutaneous aortic stent-graft insertion can be safely performed, with a low risk of both immediate and midterm access-related complications.
Archival-grade optical disc design and international standards
NASA Astrophysics Data System (ADS)
Fujii, Toru; Kojyo, Shinichi; Endo, Akihisa; Kodaira, Takuo; Mori, Fumi; Shimizu, Atsuo
Optical discs currently on the market exhibit large variations in life span among discs, making them unsuitable for certain business applications. To assess and potentially mitigate this problem, we performed accelerated degradation testing under standard ISO conditions, determined the probable disc failure mechanisms, and identified the essential criteria necessary for a stable disc composition. With these criteria as necessary conditions, we analyzed the physical and chemical changes that occur in the disc components, on the basis of which we determined technological measures to reduce these degradation processes. By applying these measures to disc fabrication, we were able to develop highly stable optical discs.
[Spontaneous resolution of a lumbar disc herniation].
Gelabert-González, M; Serramito-García, R; Aran-Echabe, E; García-Allut, A
Lumbar disc herniation is a common cause of lower leg radiculopathy and the most effective methods of treatment remain in question. Both surgical and nonsurgical treatments may provide a successful outcome in appropriately selected patients. The spontaneous resolution of herniated lumbar discs is a well-established phenomenon. The authors present a case of spontaneous regression of a herniated lumbar nucleus pulpous in a patient with radiculopathy. PMID:17497061
Disc valve for sampling erosive process streams
Mrochek, John E.; Dinsmore, Stanley R.; Chandler, Edward W.
A four-port disc valve for sampling erosive, high temperature process streams. A rotatable disc defining opposed first and second sampling cavities rotates between fired faceplates defining flow passageways positioned to be alternatively in axial alignment with the first and second cavities. Silicon carbide inserts and liners composed of .alpha. silicon carbide are provided in the faceplates and in the sampling cavities to limit erosion while providing lubricity for a smooth and precise operation when used under harsh process conditions.
Activ C cervical disc replacement for myelopathy
McGonagle, L.; Cadman, S.; Chitgopkar, S. D.; Canavan, L.; O'Malley, M.; Shackleford, I. M.
Background: Cervical disc replacement is becoming an increasingly popular treatment option for cervical myelopathy. It retains motion at the affected segment, unlike anterior cervical discectomy and fusion. The aim of this study is to assess the outcomes of a series of patients who underwent Activ C disc replacement for cervical myelopathy. Materials and Methods: A series of patients at the above Trust with clinical and radiological evidence of cervical myelopathy who were suitable for cervical disc replacement from 2007 to 2009 were included. Implants were inserted by one of two consultant surgeons {IMS, MO'M}. Patients were assessed preoperatively and at six, 12 and 24 months, postoperatively, with a visual analogue score (VAS) for neck and arm pain severity and frequency, the Neck Disability Index questionnaire (NDI) and the Centre for Epidemiologic Studies Depression questionnaire (CES-D). Results: Ten patients underwent surgery between May 2007 and July 2009, 6 women, and 4 men. Average age was 54 years (40-64). Disc levels replaced were: four at C4-5; eight at C5-6; seven at C6-7. Three patients had one disc replaced, five patients had two discs replaced, and two patients had three discs replaced. The VAS for neck pain improved from 5.9 pre-operatively to 1.4-24 months postoperatively and the VAS arm pain improved from 5.4 to 2.6. The NDI improved from 51% preoperatively to 26.8% at 24 months postoperatively. The CES-D showed a slight increase from 19.5 preoperatively to 21.7 at 24 months, postoperatively. Conclusion: Cervical decompression and disc replacement improves pain and function in patients with cervical myelopathy. This benefit is maintained at 24 months post op, with no cases requiring revision. PMID:23125494
Investigation of cryogenic rupture disc design
NASA Technical Reports Server (NTRS)
Keough, J. B.; Oldland, A. H.
Rupture disc designs of both the active (command actuated) and passive (pressure ruptured) types were evaluated for performance characteristics at cryogenic temperatures and for capability to operate in a variety of cryogens, including gaseous and liquid fluorine. The test results, coupled with information from literature and industry searches, were used to establish a statement of design criteria and recommended practices for application of rupture discs to cryogenic rocket propellant feed and vent systems.
Mach disc formation in cylindrical recovery systems
Morris, C.E.; McQueen, R.G.; Marsh, S.P.
Cylindrical recovery systems have been used to shock-load polymers to pressures exceeding 50 GPa. In order to determine the pressures generated in these recovery systems the formation of the Mach disc on axis and its approach to steady state was monitored. The relation of the Mach disc diameter to the lateral dimension of the high explosive used to compress the polymer samples was also investigated.
Discovery of the Fomalhaut C debris disc
NASA Astrophysics Data System (ADS)
Kennedy, G. M.; Wyatt, M. C.; Kalas, P.; Duchêne, G.; Sibthorpe, B.; Lestrade, J.-F.; Matthews, B. C.; Greaves, J.
Fomalhaut is one of the most interesting and well-studied nearby stars, hosting at least one planet, a spectacular debris ring and two distant low-mass stellar companions (TW PsA and LP 876-10, a.k.a. Fomalhaut B and C). We observed both companions with Herschel, and while no disc was detected around the secondary, TW PsA, we have discovered the second debris disc in the Fomalhaut system, around LP 876-10. This detection is only the second case of two debris discs seen in a multiple system, both of which are relatively wide (≳3000 au for HD 223352/40 and 158 kau [0.77 pc] for Fomalhaut/LP 876-10). The disc is cool (24 K) and relatively bright, with a fractional luminosity Ldisc/L⋆ = 1.2 × 10-4, and represents the rare observation of a debris disc around an M dwarf. Further work should attempt to find if the presence of two discs in the Fomalhaut system is coincidental, perhaps simply due to the relatively young system age of 440 Myr, or if the stellar components have dynamically interacted and the system is even more complex than it currently appears.
Proteomic Signature of the Murine Intervertebral Disc
McCann, Matthew R.; Patel, Priya; Frimpong, Agya; Xiao, Yizhi; Siqueira, Walter L.; Séguin, Cheryle A.
Low back pain is the most common musculoskeletal problem and the single most common cause of disability, often attributed to degeneration of the intervertebral disc. Lack of effective treatment is directly related to our limited understanding of the pathways responsible for maintaining disc health. While transcriptional analysis has permitted initial insights into the biology of the intervertebral disc, complete proteomic characterization is required. We therefore employed liquid chromatography electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) protein/peptide separation and mass spectrometric analyses to characterize the protein content of intervertebral discs from skeletally mature wild-type mice. A total of 1360 proteins were identified and categorized using PANTHER. Identified proteins were primarily intracellular/plasma membrane (35%), organelle (30%), macromolecular complex (10%), extracellular region (9%). Molecular function categorization resulted in three distinct categories: catalytic activity (33%), binding (molecule interactions) (29%), and structural activity (13%). To validate our list, we confirmed the presence of 14 of 20 previously identified IVD-associated markers, including matrix proteins, transcriptional regulators, and secreted proteins. Immunohistochemical analysis confirmed distinct localization patterns of select protein with the intervertebral disc. Characterization of the protein composition of healthy intervertebral disc tissue is an important first step in identifying cellular processes and pathways disrupted during aging or disease progression. PMID:25689066
Modeling Jupiter's current disc: Pioneer 10 outbound
Jones, D.E.; Melville, J.G. II; Blake, M.L.
The magnetic field of the Jovian current disc has been modeled by using Euler functions and the Biot-Savart law applied to a series of concentric, but not necessarily coplanar, current rings. We find that a best fit to the Pioneer 10 outbound perturbation magnetic field data (B/sub total/-B/sub dipole/) is obtained if the current disc is twisted (outer edges increasingly lag behind inner edges with radial distance) and also bent so as to tend toward parallelism with the Jovigraphic equator. The inner and outer radii of the disc appear to be about 7 R/sub J/ and 150 R/sub J/, respectively, although some indication of a changing magnetopause location is apparent in the data. Because of the observed current disc penetrations, the bent disc also requires a deformation in the form of a bump or wrinkle whose axis tends also to exhibit spiraling. The radial dependence of the azimuthal current in the disc is not described by a simple power law, the outer region showing a smaller power law dependence. Modeling of the azimuthal field shows it to be due to a thin radial current sheet, but there is some evidence that this may, in fact, be due in large part to penetration of a tail current sheet as suggested by the Voyager observations.
Optic disc anomalies and frontonasal dysplasia
Hodgkins, P; Lees, M; Lawson, J; Reardon, W; Leitch, J; Thorogood, P; Winter, R; Taylor, D
AIMS—To document the optic disc abnormalities in patients with frontonasal dysplasia in association with basal encephalocele. METHODS—Names and hospital numbers of patients with midline clefts were obtained from the ophthalmology and genetics database. Six patients were identified who had the following common findings: midline facial cleft with midline cleft lip and palate; hypertelorism; absent corpus callosum; basal (sphenoethmoidal) encephalocele; and pituitary deficiency (five out of six cases). Ophthalmic examination was performed with fundal photography where possible. RESULTS—Two patients had unilateral and one a bilateral peripapillary staphyloma. Two patients had bilateral optic disc hypoplasia and one appeared to have a peripapillary staphyloma in one eye and a morning glory disc in the other. CONCLUSION—Optic disc abnormalities were found in all patients with this constellation of clinical findings. This association appears to represent a distinct subgroup within the spectrum of frontonasal dysplasia. The presence of midline facial anomalies and any dysplastic disc should alert the physician as to the presence of an encephalocele. Keywords: frontonasal dysplasia; optic disc; encephalocele PMID:9602627
The diversity of thick galactic discs
NASA Astrophysics Data System (ADS)
Kasparova, Anastasia V.; Katkov, Ivan Yu.; Chilingarian, Igor V.; Silchenko, Olga K.; Moiseev, Alexey V.; Borisov, Svyatoslav B.
Although thick stellar discs are detected in nearly all edge-on disc galaxies, their formation scenarios still remain a matter of debate. Due to observational difficulties, there is a lack of information about their stellar populations. Using the Russian 6-m telescope BTA we collected deep spectra of thick discs in three edge-on S0-a disc galaxies located in different environments: NGC 4111 in a dense group, NGC 4710 in the Virgo cluster, and NGC 5422 in a sparse group. We see intermediate age (4-5 Gyr) metal rich ([Fe/H] ˜- 0.2…0.0 dex) stellar populations in NGC 4111 and NGC 4710. On the other hand, NGC 5422 does not harbour young stars, its disc is thick and old (10 Gyr), without evidence for a second component, and its α-element abundance suggests a 1.5-2 Gyr long formation epoch implying its formation at high redshift. Our results suggest the diversity of thick disc formation scenarios.
Circumplanetary disc or circumplanetary envelope?
NASA Astrophysics Data System (ADS)
Szulágyi, J.; Masset, F.; Lega, E.; Crida, A.; Morbidelli, A.; Guillot, T.
We present three-dimensional simulations with nested meshes of the dynamics of the gas around a Jupiter mass planet with the JUPITER and FARGOCA codes. We implemented a radiative transfer module into the JUPITER code to account for realistic heating and cooling of the gas. We focus on the circumplanetary gas flow, determining its characteristics at very high resolution (80 per cent of Jupiter's diameter). In our nominal simulation where the temperature evolves freely by the radiative module and reaches 13000 K at the planet, a circumplanetary envelope was formed filling the entire Roche lobe. Because of our equation of state is simplified and probably overestimates the temperature, we also performed simulations with limited maximal temperatures in the planet region (1000, 1500, and 2000 K). In these fixed temperature cases circumplanetary discs (CPDs) were formed. This suggests that the capability to form a CPD is not simply linked to the mass of the planet and its ability to open a gap. Instead, the gas temperature at the planet's location, which depends on its accretion history, plays also fundamental role. The CPDs in the simulations are hot and cooling very slowly, they have very steep temperature and density profiles, and are strongly sub-Keplerian. Moreover, the CPDs are fed by a strong vertical influx, which shocks on the CPD surfaces creating a hot and luminous shock-front. In contrast, the pressure supported circumplanetary envelope is characterized by internal convection and almost stalled rotation.
NASA Astrophysics Data System (ADS)
de Riese, Cornelia
This presentation is designed as a brief overview of laser use in gynecology, for non-medical researchers involved in development of new laser techniques. The literature of the past decade is reviewed. Differences in penetration, absorption, and suitable delivery media for the beams dictate clinical application. The use of CO2 laser in the treatment of uterine cervical intraepithelial lesions is well established and indications as well as techniques have not changed over 30 years. The Cochrane Systematic Review from 2000 suggests no obviously superior technique. CO2 laser ablation of the vagina is also established as a safe treatment modality for VAIN. CO2 laser permits treatment of lesions with excellent cosmetic and functional results. The treatment of heavy menstrual bleeding by destruction of the endometrial lining using various techniques has been the subject of a 2002 Cochran Database Review. Among the compared treatment modalities are newer and modified laser techniques. Conclusion by reviewers is that outcomes and complication profiles of newer techniques compare favorably with the gold standard of endometrial resection. The ELITT diode laser system is one of the new successful additions. CO2 laser is also the dominant laser type used with laparoscopy for ablation of endometriotic implants. Myoma coagulation or myolysis with Nd:Yag laser through the laparoscope or hysteroscope is a conservative treatment option. Even MRI guided percutaneous approaches have been described. No long-term data are available.
A novel collinear optical system with annulus mirrors for holographic disc driver
NASA Astrophysics Data System (ADS)
Wang, Ye
This paper focus on a novel collinear lens system with annulus mirrors for holographic disc driver, both information beam and reference beam are use same laser beam. The expanded and parallel laser beam, center part of it as the information beam then through Fourier transform lens, the beam around center part as a reference beam. On this axis, the ring reference beam reflected by two annulus shaped mirrors, then became a convergent beam, together with the information beam which through the first Fourier transform lens then produce holographic pattern to be write into the holographic disc behind of them, this lens system with two mirrors made the angle between information beam and reference beam more wide, can improved the multiplex level of holographic storage. Pair of Fourier transform lens with advance performance is designed in this paper.
Percutaneous endoscopic management of intrahepatic stones in patients with altered biliary anatomy: A case series.
Bhandari, Suryaprakash; Bathini, Rajesh; Sharma, Atul; Maydeo, Amit
Incidence of primary intrahepatic stones (IHS) in India is very less as compared to the Far East. However patients with altered biliary anatomy are prone for IHS formation secondary to anastomotic stricture formation. Indian data on percutaneous endoscopic management of IHS is scare. Five patients with IHS were managed percutaneously. All patients had undergone Roux-en-Y hepaticojejunostomy and were not suitable for direct endoscopic intervention. All patients underwent percutaneous biliary drainage followed by cholangioscopy-guided laser lithotripsy. Crushed stones were pushed across the anastomotic site using basket/balloon and ductal clearance was achieved. Good stone pulverization could be achieved in five patients (100 %). Complete ductal clearance could be achieved in all patients (100 %). Cholangioscopy-guided treatment of IHS can be valuable alternative to surgery in select group of patients especially those having dilated biliary tree with absence of intrahepatic strictures. However long-term follow up studies are required to see for recurrence of stone formation. PMID:27041379
Complications of Percutaneous Nephrostomy, Percutaneous Insertion of Ureteral Endoprosthesis, and Replacement Procedures
Kaskarelis, Ioannis S.; Papadaki, Marina G.; Malliaraki, Niki E.; Robotis, Epaminondas D.; Malagari, Katerina S.; Piperopoulos, Ploutarchos N.
Purpose: The aim of the present study was to record and identify the frequency of complications following percutaneous nephrostomy, replacement of nephrostomy drains and percutaneous insertion of ureteral endoprostheses.Methods: During a 10-year period 341 patients were referred to our department with indications for percutaneous nephrostomy and/or percutaneous insertion of a ureteral endoprosthesis, and a total of 1036 interventional procedures were performed (nephrostomy, catheter change, stenting).Results: There were three major complications (0.29%): two patients died during the first 30 days after the procedure, due to aggravation of their condition caused by the procedure, and one patient had retroperitoneal bleeding requiring surgery. There were 76 complications of intermediate severity (7.33%): catheter or stent displacement (n = 37, 3.57%) catheter occlusion (n = 18, 1.73%), hematuria (n = 12, 1.16%), and urinary tract infection (n = 9, 0.87%). The 55 minor complications (5.3%) comprised inflammation of the skin at the site of insertion of the percutaneous catheter.Conclusion: The small number of complications observed during acts of interventional uroradiology prove transcutaneous manipulations to be safe medical procedures.
Tracing Planets in Circumstellar Discs. Observability of Large-scale Disc Structures with ALMA
NASA Astrophysics Data System (ADS)
Ruge, Jan Philipp; Wolf, Sebastian; Uribe, Ana L.; Klahr, Hubert H.
Planets are assumed to form in circumstellar discs around young stellar objects. The additional gravitational potential of a planet perturbs the disc and leads to characteristic structures, i.e. spiral waves and gaps, in the disc density profile. We perform a large-scale parameter study on the observability of these planet-induced structures in circumstellar discs in the (sub)mm wavelength range for the Atacama Large (Sub)Millimeter Array (ALMA). On the basis of hydrodynamical and magneto-hydrodynamical simulations of star-disc-planet models we calculate the disc temperature structure and (sub)mm images of these systems. These are used to derive simulated ALMA maps. Because appropriate objects are frequent in the Taurus-Auriga region, we focus on a distance of 140 pc and a declination of ≈ 20°. The explored range of star-disc-planet configurations consists of six hydrodynamical simulations (including magnetic fields and different planet masses), nine disc sizes with outer radii ranging from 9 AU to 225 AU, 15 total disc masses in the range between 2.67·10-7 M⊙ and 4.10·10-2 M⊙, six different central stars and two different grain size distributions, resulting in 10 000 disc models. At almost all scales and in particular down to a scale of a few AU, ALMA is able to trace disc structures induced by planet-disc interaction or the influence of magnetic fields in the wavelength range between 0.4...2.0 mm. In most cases, the optimum angular resolution is limited by the sensitivity of ALMA. However, within the range of typical masses of protoplane tary discs (0.1 M⊙...0.001 M⊙) the disc mass has a minor impact on the observability. At the distance of 140 pc it is possible to resolve discs down to 2.67·10-6 M⊙ and trace gaps in discs with 2.67·10-4 M⊙ with a signal-to-noise ratio greater than three. In general, it is more likely to trace planet-induced gaps in magneto-hydrodynamical disc models, because gaps are wider in the presence of magnetic fields [1
Modified Retroperitoneal Access for Percutaneous Intervention after Pancreaticoduodenectomy
Quek, Lawrence H H
Percutaneous access to the surgical bed after pancreaticoduodenectomy can be a challenge, due to the post-operative anatomy alteration. However, immediate complications, such as surgical bed abscess or suspected tumor recurrence, are often best accessed percutaneously, as open surgical or endoscopic approaches are often difficult, if not impossible. We, hereby, describe a safe approach that is highly replicable, in accessing the surgical bed for percutaneous intervention, following pancreaticoduodenectomy. PMID:23690711
Modeling and optimization of an elastic arthroplastic disc for a degenerated disc
NASA Astrophysics Data System (ADS)
Ghouchani, Azadeh; Ravari, Mohammad; Mahmoudi, Farid
A three-dimensional finite element model (FEM) of the L3-L4 motion segment using ABAQUS v 6.9 has been developed. The model took into account the material nonlinearities and is imposed different loading conditions. In this study, we validated the model by comparison of its predictions with several sets of experimental data. Disc deformation under compression and segmental rotational motions under moment loads for the normal disc model agreed well with the corresponding in vivo studies. By linking ABAQUS with MATLAB 2010.a, we determined the optimal Young s modulus as well as the Poisson's ratio for the artificial disc under different physiologic loading conditions. The results of the present study confirmed that a well-designed elastic arthroplastic disc preferably has an annulus modulus of 19.1 MPa and 1.24 MPa for nucleus section and Poisson ratio of 0.41 and 0.47 respectively. Elastic artificial disc with such properties can then achieve the goal of restoring the disc height and mechanical function of intact disc under different loading conditions and so can reduce low back pain which is mostly caused due to disc degeneration.
Preparation of ormetoprim-sulfadimethoxine-medicated discs for disc diffusion assay
Technology Transfer Automated Retrieval System (TEKTRAN)
Romet ( a blend of ormetoprim and sulfadimethoxine) is a type A medicated article for the manufacture of medicated feed in the catfish industry. Recently, the commercial manufacture of ormetoprim-sulfadimethoxine susceptibility discs was discontinued. Ormetoprim-sulfadimethoxine discs were prepare...
Brachiocephalic artery haemorrhage during percutaneous tracheostomy.
Sharma, S D; Kumar, G; Hill, C S; Kaddour, H
Percutaneous tracheostomy was performed on a 69-year-old woman to facilitate weaning. Insertion of the size 7 tracheostomy tube resulted in profuse bleeding around the tracheostomy site. On inflation of the tracheostomy balloon, the bleeding stopped. Urgent computed tomography demonstrated the brachiocephalic artery was abnormally high and lying in an oblique fashion over the trachea, and the tracheostomy tube was displacing the trachea posteriorly. Surgical repair of the defect in the brachiocephalic artery was undertaken and a surgical tracheostomy was performed in theatre. This case raises important issues about the potential dangers of percutaneous tracheostomy in cases of abnormal anatomy. It also emphasises the importance of direct visualisation of the seeker needle using the endoscope. In cases where there is a suspicion of abnormal anatomy, it is safer to obtain preprocedural imaging or perform a surgical tracheostomy. PMID:25723674
Embolic protection devices in percutaneous coronary intervention.
Meneguz Moreno, Rafael A; Costa, José R; Costa, Ricardo A; Abizaid, Alexandre
Clinical benefit of percutaneous coronary intervention (PCI) depends on both angiographic success at lesion site as well as the restoration of adequate macro and microvascular perfusion. The pathophysiology of embolization from coronary lesions during PCI is multifactorial, being more frequently observed in patients with acute coronary syndrome and in those with lesions at saphenous vein graft (SVG). In this population, despite successful epicardial intervention, distal tissue perfusion may still be absent in up to a quarter of all PCI. Multiple devices and pharmacologic regimens have been developed and refined in an attempt to protect the microvascular circulation during PCI. Among them, embolic protection devices have raised as an attractive adjunctive toll due to their ability to retain debris and potentially prevent distal embolization, reducing major adverse cardiac events. Currently, their use has been validated for the treatment of SVG lesions but failed to show effectiveness in the percutaneous approach of acute coronary syndrome patients, including those with ST elevation myocardial infarction. PMID:27007782
Percutaneous closure of the patent foramen ovale.
Surmely, J-F; Meier, B
A patent foramen ovale (PFO) is a common finding present in 25% of the population. A relationship between PFO and several clinical conditions such as stroke, migraine, platypnea-orthodeoxia syndrome, neurological decompression illness in divers, high altitude pulmonary edema, sleep apnea, and economy class syndrome have been documented. Observational non-randomized studies have shown percutaneous PFO closure more effective than medical treatment for stroke prevention, in particular in patients with complete closure as well as in patients with more than one cerebrovascular event at baseline. In the case of migraine, PFO closure has been shown to result in a marked reduction in migraine burden or migraine days. PFO anatomy, epidemiological data on associated clinical conditions, comparison between percutaneous closure and medical treatment, as well as the technical aspect of the procedure are described in this review. PMID:17912171
Percutaneous Large Arterial Access Closure Techniques.
McGraw, Charles J; Gandhi, Ripal T; Vatakencherry, Geogy; Baumann, Frederic; Benenati, James F
Endovascular repair has replaced open surgical repair as the standard of care for treatment of abdominal and thoracic aortic aneurysms in appropriately selected patients owing to its decreased morbidity and length of stay and excellent clinical outcomes. Similarly, there is a progressive trend toward total percutaneous repair of the femoral artery using percutaneous suture-mediated closure devices over open surgical repair due to decreased complications and procedure time. This article describes the techniques of closure for large-bore vascular access most commonly used in endovascular treatment of abdominal and thoracic aortic aneurysms, but could similarly be applied to any procedure requiring large-bore arterial access, such as transcatheter aortic valve replacement. PMID:26070624
Reoperations Following Cervical Disc Replacement
Skovrlj, Branko; Lee, Dong-Ho; Caridi, John Michael
Cervical disc replacement (CDR) has emerged as an alternative surgical option to cervical arthrodesis. With increasing numbers of patients and longer follow-ups, complications related to the device and/or aging spine are growing, leaving us with a new challenge in the management and surgical revision of CDR. The purpose of this study is to review the current literature regarding reoperations following CDR and to discuss about the approaches and solutions for the current and future potential complications associated with CDR. The published rates of reoperation (mean, 1.0%; range, 0%-3.1%), revision (mean, 0.2%; range, 0%-0.5%), and removal (mean, 1.2%; range, 0%-1.9%) following CDR are low and comparable to the published rates of reoperation (mean, 1.7%; range; 0%-3.4%), revision (mean, 1.5%; range, 0%-4.7%), and removal (mean, 2.0%; range, 0%-3.4%) following cervical arthrodesis. The surgical interventions following CDR range from the repositioning to explantation followed by fusion or the reimplantation to posterior foraminotomy or fusion. Strict patient selection, careful preoperative radiographic review and surgical planning, as well as surgical technique may reduce adverse events and the need for future intervention. Minimal literature and no guidelines exist for the approaches and techniques in revision and for the removal of implants following CDR. Adherence to strict indications and precise surgical technique may reduce the number of reoperations, revisions, and removals following CDR. Long-term follow-up studies are needed, assessing the implant survivorship and its effect on the revision and removal rates. PMID:26097667
1064-nm Nd:YAG laser nucleotomy
NASA Astrophysics Data System (ADS)
Vari, Sandor G.; Pergadia, Vani R.; Shi, Wei-Qiang; Snyder, Wendy J.; Fishbein, Michael C.; Grundfest, Warren S.
The high incidence of patients with clinical and neurological symptoms of lumbar disc herniation has spurred the development of less invasive and more cost efficient methods to treat patients. In this study we evaluated pulsed and continuous wave (cw) 1064 nm Nd:YAG laser ablation and induced thermal damage in sheep intervertebral disc. We used the Heraeus LaserSonics Hercules 5040 (Nd:YAG) laser system and 400 micrometers bare and 600 micrometers ball-tipped fibers in cw and pulsed mode. For the laser parameters and fibers used in this study, ablation of the intervertebral disc was successful and thermal damage did not exceed 0.5 mm. Varying beam diameters and focusing abilities (i.e., bare and ball) did not produce any difference in the coagulation thermal effect.
Percutaneous delivery of econazole using microemulsion as vehicle: formulation, evaluation and vesicle-skin interaction.
Ge, Shumin; Lin, Yuanyuan; Lu, Haoyang; Li, Qi; He, Jian; Chen, Bao; Wu, Chuanbin; Xu, Yuehong
This project was carried out to exploit the feasibility of using microemulsion (ME) as an alternative carrier for percutaneous delivery econazole nitrate (ECN) and elucidate the underlying mechanism of permeation enhancement. The ME was developed based on Labrafil M 1944 Cs as oil phase, Solutol HS15 and Span 80 as surfactants, Transcutol P as cosurfactant and water as aqueous phase. The solubility of ECN was firstly determined for screening the ingredients of the system. Pseudo-ternary phase diagrams were constructed to formulate ME and select surfactant and cosurfactant. Central composite design-response surface methodology (CCD-RSM) was utilized to optimize the formulation of ME. The ECN loaded ME was characterized in terms of morphology, particle size and size distribution, pH value, refractive index, viscosity and conductivity, and storage stability of the ECN loaded ME was assayed. Percutaneous permeation of ECN from ME in vitro through rat skin was investigated in comparison with PBS aqueous suspension (1%, w/w), and results showed that ME enhanced drug retention in the skin and permeation through the skin, the enhancement of ME on skin deposition was further visualized through fluorescent-labeled ME by confocal laser scanning microscope (CLSM). The action mechanism of ME on improving percutaneous delivery was studied by performing a pretreatment test. It can speculate that ME does not simply behave as enhancer but it also acts as drug carrier. Furthermore, ME-skin interaction was elucidated through transmission electron microscope (TEM), and attenuated total reflectance fourier-transform infrared (ATR-FTIR). TEM was performed to visualize the micro morphological change of skin. ATR-FTIR was carried out to investigate the molecular vibrations of the components of stratum corneum (SC). The results indicate that the ME system may be a promising vehicle for percutaneous delivery of ECN. PMID:24530389
Bilothorax as a complication of percutaneous transhepatic biliary drainage.
Sano, Atsushi; Yotsumoto, Takuma
We report two cases of bilothorax that occurred as a complication of percutaneous transhepatic biliary drainage. In an 86-year-old woman who had undergone percutaneous transhepatic biliary drainage for obstructive jaundice, bilothorax occurred after accidental removal of the tube. She recovered with chest drainage only. An 83-year-old man who had undergone percutaneous transhepatic biliary drainage for cholecystitis developed bilothorax with infection. He recovered with thoracoscopic curettage. Although bilothorax is a rare complication of percutaneous transhepatic biliary drainage, appropriate diagnosis and prompt treatment is important, especially when bilothorax is accompanied by infection. PMID:26294694
Structures induced by companions in galactic discs
NASA Astrophysics Data System (ADS)
Kyziropoulos, P. E.; Efthymiopoulos, C.; Gravvanis, G. A.; Patsis, P. A.
Using N-body simulations we study the structures induced on a galactic disc by repeated flybys of a companion in decaying eccentric orbit around the disc. Our system is composed by a stellar disc, bulge and live dark matter halo, and we study the system's dynamical response to a sequence of a companion's flybys, when we vary i) the disc's temperature (parameterized by Toomre's Q-parameter) and ii) the companion's mass and initial orbit. We use a new 3D Cartesian grid code: MAIN (Mesh-adaptive Approximate Inverse N-body solver). The main features of MAIN are reviewed, with emphasis on the use of a new Symmetric Factored Approximate Sparse Inverse (SFASI) matrix in conjunction with the multigrid method that allows the efficient solution of Poisson's equation in three space variables. We find that: i) companions need to be assigned initial masses in a rather narrow window of values in order to produce significant and more long-standing non-axisymmetric structures (bars and spirals) in the main galaxy's disc by the repeated flyby mechanism. ii) a crucial phenomenon is the antagonism between companion-excited and self-excited modes on the disc. Values of Q > 1.5 are needed in order to allow for the growth of the companion-excited modes to prevail over the the growth of the disc's self-excited modes. iii) We give evidence that the companion-induced spiral structure is best represented by a density wave with pattern speed nearly constant in a region extending from the ILR to a radius close to, but inside, corotation.
Cervical disc hernia operations through posterior laminoforaminotomy
Yolas, Coskun; Ozdemir, Nuriye Guzin; Okay, Hilmi Onder; Kanat, Ayhan; Senol, Mehmet; Atci, Ibrahim Burak; Yilmaz, Hakan; Coban, Mustafa Kemal; Yuksel, Mehmet Onur; Kahraman, Umit
Objective: The most common used technique for posterolateral cervical disc herniations is anterior approach. However, posterior cervical laminotoforaminomy can provide excellent results in appropriately selected patients with foraminal stenosis in either soft disc prolapse or cervical spondylosis. The purpose of this study was to present the clinical outcomes following posterior laminoforaminotomy in patients with radiculopathy. Materials and Methods: We retrospectively evaluated 35 patients diagnosed with posterolateral cervical disc herniation and cervical spondylosis with foraminal stenosis causing radiculopathy operated by the posterior cervical keyhole laminoforaminotomy between the years 2010 and 2015. Results: The file records and the radiographic images of the 35 patients were assessed retrospectively. The mean age was 46.4 years (range: 34-66 years). Of the patients, 19 were males and 16 were females. In all of the patients, the neurologic deficit observed was radiculopathy. The posterolaterally localized disc herniations and the osteophytic structures were on the left side in 18 cases and on the right in 17 cases. In 10 of the patients, the disc level was at C5-6, in 18 at C6-7, in 2 at C3-4, in 2 at C4-5, in 1 at C7-T1, in 1 patient at both C5-6 and C6-7, and in 1 at both C4-5 and C5-6. In 14 of these 35 patients, both osteophytic structures and protruded disc herniation were present. Intervertebral foramen stenosis was present in all of the patients with osteophytes. Postoperatively, in 31 patients the complaints were relieved completely and four patients had complaints of neck pain and paresthesia radiating to the arm (the success of operation was 88.5%). On control examinations, there was no finding of instability or cervical kyphosis. Conclusion: Posterior cervical laminoforaminotomy is an alternative appropriate choice in both cervical soft disc herniations and cervical stenosis. PMID:27217655
Reconstructing the star formation history of the Milky Way disc(s) from chemical abundances
NASA Astrophysics Data System (ADS)
Snaith, O.; Haywood, M.; Di Matteo, P.; Lehnert, M. D.; Combes, F.; Katz, D.; Gómez, A.
We develop a chemical evolution model to study the star formation history of the Milky Way. Our model assumes that the Milky Way has formed from a closed-box-like system in the inner regions, while the outer parts of the disc have experienced some accretion. Unlike the usual procedure, we do not fix the star formation prescription (e.g. Kennicutt law) to reproduce the chemical abundance trends. Instead, we fit the abundance trends with age to recover the star formation history of the Galaxy. Our method enables us to recover the star formation history of the Milky Way in the first Gyrs with unprecedented accuracy in the inner (R < 7-8 kpc) and outer (R > 9-10 kpc) discs, as sampled in the solar vicinity. We show that half the stellar mass formed during the thick-disc phase in the inner galaxy during the first 4-5 Gyr. This phase was followed by a significant dip in star formation activity (at 8-9 Gyr) and a period of roughly constant lower-level star formation for the remaining 8 Gyr. The thick-disc phase has produced as many metals in 4 Gyr as the thin-disc phase in the remaining 8 Gyr. Our results suggest that a closed-box model is able to fit all the available constraints in the inner disc. A closed-box system is qualitatively equivalent to a regime where the accretion rate maintains a high gas fraction in the inner disc at high redshift. In these conditions the SFR is mainly governed by the high turbulence of the interstellar medium. By z ~ 1 it is possible that most of the accretion takes place in the outer disc, while the star formation activity in the inner disc is mostly sustained by the gas that is not consumed during the thick-disc phase and the continuous ejecta from earlier generations of stars. The outer disc follows a star formation history very similar to that of the inner disc, although initiated at z ~ 2, about 2 Gyr before the onset of the thin-disc formation in the inner disc.
Microcatheter use for difficult percutaneous biliary procedures.
Brountzos, Elias N; Kelekis, Alexis D; Ptohis, Nikolaos; Kotsioumba, Ioanna; Misiakos, Evangelos; Perros, George; Gouliamos, Athanasios D
Percutaneous biliary drainage procedures in patients with nondilated ducts are demanding, resulting in lower success rates than in patients with bile duct dilatation. Pertinent clinical settings include patients with iatrogenic bile leaks, diffuse cholangiocarcinomas, and sclerosing cholangitis. We describe a method to facilitate these procedures with the combined use of a 2.7-Fr microcatheter and a 0.018-in. hydrophilic wire. PMID:18320271
Percutaneous Transhepatic Biliary Drainage Complicated by Bilothorax.
Kim, Stephanie H; Zangan, Steven M
Percutaneous transhepatic biliary drainage (PTBD) is a well-established and safe technique for the management of biliary obstructions and leaks. While approach is variable based on operator preference, patient anatomy, and indications; PTBD is commonly performed via a right-sided intercostal route. With a right-sided approach, pleural complications may be encountered. The authors describe a case of a right PTBD complicated by a leak into the pleural space, with the subsequent development of bilothorax. PMID:27053829
Percutaneous absorption in diseased skin: an overview.
Chiang, Audris; Tudela, Emilie; Maibach, Howard I
The stratum corneum's (SC) functions include protection from external hazardous environments, prevention of water loss and regulation of body temperature. While intact skin absorption studies are abundant, studies on compromised skin permeability are less common, although products are often used to treat affected skin. We reviewed literature on percutaneous absorption through abnormal skin models. Tape stripping is used to disrupt water barrier function. Studies demonstrated that physicochemical properties influence the stripping effect: water-soluble drugs are more affected. Abrasion did not affect absorption as much. Freezing is commonly used to preserve skin. It does not seem to modify water absorption, but still increases the penetration of compounds. Comparatively, heating the skin consistently increased percutaneous absorption. Removing SC lipids may increase percutaneous absorption of drugs. Many organic solvents are employed to delipidize. Delipidization with chloroform-methanol increased hydrophilic compound permeability, but not lipophilic. Acetone pre-treatment enhanced hydrophilic compound penetration. More data is needed to determine influence on highly lipophilic compound penetration. Sodium lauryl sulfate (SLS) induces irritant dermatitis and is frequently used as a model. Studies revealed that SLS increases hydrophilic compound absorption, but not lipophilic. However, skin irritation with other chemicals increases lipophilic penetration as much as hydrophilic. Animal studies show that UV exposure increases percutaneous absorption whereas human studies do not. Human studies show increased penetration in psoriatic and atopic dermatitis skin. The data summarized here begin to characterize flux alteration associated with damaged skin. Understanding the degree of alteration requires interpretation of involved conditions and the enlarging of our database to a more complete physicochemical spectrum. PMID:22912973
Percutaneous Vertebral Body Augmentation: An Updated Review
Omidi-Kashani, Farzad
There are many medical conditions like osteoporosis, tumor, or osteonecrosis that weaken the structural strength of the vertebral body and prone it to fracture. Percutaneous vertebral augmentation that is usually applied by polymethylmethacrylate is a relatively safe, effective, and long lasting procedure commonly performed in these situations. In this paper, we updated a review of biomechanics, indications, contraindications, surgical techniques, complications, and overall prognosis of these minimally invasive spinal procedures. PMID:25379561
Cardiac resynchronisation therapy after percutaneous mitral annuloplasty
Swampillai, Janice
Percutaneous approaches to reduce mitral regurgitation in ischemic cardiomyopathy have stirred interest recently. Patients with ischemic cardiomyopathy and functional mitral regurgitation often meet criteria for cardiac resynchronisation therapy to improve left ventricular function as well as mitral regurgitation, and alleviate symptoms. This case shows that implantation of a pacing lead in the coronary sinus to restore synchronous left and right ventricular contraction is feasible, despite the presence of a remodeling device in the coronary sinus. PMID:27182527
Tearing up the disc: misaligned accretion on to a binary
NASA Astrophysics Data System (ADS)
Nixon, Chris; King, Andrew; Price, Daniel
In a recent paper, we have shown that the evolution of a misaligned disc around a spinning black hole can result in tearing the disc into many distinct planes. Tearing discs with random orientations produce direct dynamical accretion on to the hole in ≈70 per cent of all cases. Here, we examine the evolution of a misaligned disc around a binary system. We show that these discs are susceptible to tearing for almost all inclinations. We also show that tearing of the disc can result in a significant acceleration of the disc evolution and subsequent accretion on to the binary - by factors up to 104 times that of a coplanar prograde disc with otherwise identical parameters. This provides a promising mechanism for driving mergers of supermassive black hole (SMBH) binaries on time-scales much shorter than a Hubble time. Disc tearing also suggests new observational signatures of accreting SMBH binaries and other systems such as protostellar binaries.
Disc-shaped colloids interacting in a nematic liquid crystal
NASA Astrophysics Data System (ADS)
Antipova, Alena; Denniston, Colin
We studied the behavior of pairs of disc-shaped colloidal particles in a nematic liquid crystal using Lattice Boltzmann algorithm. Without any external forces the position of the disc with respect to the liquid crystal director minimizes the free energy of the system and no distortion of the director field is observed. When the rotating magnetic field is present, the torque on the disc with homeotropic surface anchoring should change with analogy to electrostatic energy, which implies the disc continues turning following the field. However, when the disc reaches some critical position and the director field around it is highly distorted, the disc suddenly flips to minimize the free energy. Position and motion of pairs of such discs under similar conditions can be controlled by the angular velocity of magnetic field, it's magnitude and initial configuration of the system. As a result of analysis of discs' dynamics, a new way to control self-organization of disc particles was produced.
In vitro preliminary study of osteoblast response to surface roughness of titanium discs and topical application of melatonin
Pérez-Martínez, Carolina; Martín-del-Llano, José-Javier; Carda-Batalla, Carmen; Labaig-Rueda, Carlos
Objectives: To observe human osteoblast behavior cultured in vitro on titanium discs (Ti) in relation to surface roughness and melatonin application. Study Design: Human osteoblasts (MG-63) were cultured on 60 Ti6Al4V discs divided into three groups: Group I: discs treated with dual acid etching; Group II dual acid etching and blasting with calcium phosphate particles; Group III (control) machined discs. Surface roughness and topography of the discs were examined with scanning electron microscope (SEM) and confocal laser scanning electron microscope( CLSM). Osteoblast adhesion, proliferation and cell morphology were determined by means of fluorescence microscopy with Image-Pro Plus software and SEM. Results: Group II presented the roughest discs, while the least rough were Group III. Cell adhesion was greatest in Group II. The addition of melatonin improved cell proliferation. Conclusions: 1. Surface treatments (dual acid etching, calcium phosphate impaction) increase surface roughness in comparison with machined titanium. 2. Greater surface roughness tends to favor cell adhesion after 24-hour cell culture. 3. The addition of melatonin tends to favor osteoblast proliferation. Key words:Osteoblasts, titanium, roughness, melatonin, dental implants, osseointegration. PMID:25129252
Management of hemorrhage after percutaneous renal surgery.
Gallucci, M; Fortunato, P; Schettini, M; Vincenzoni, A
Percutaneous renal surgery is routine therapy for a number of renal pathologies. It is a technique not without complications, often serious ones, of which the worst is bleeding. We reviewed our experience of the incidence, etiology, and management of this serious complication to determine a protocol of treatment that will minimize the consequences. Between 1984 and 1996, we carried out 976 percutaneous operations for reno-calix stones, pyeloureteral junction stenosis, neoplasia of the renal pelvis, diagnosis, and ureteral prostheses. In all cases, the percutaneous access was achieved through a lower calix in the posterior axillary line with the patient in a prone position. The lithotripsy was performed with ultrasound and balistic energy lithotripters. Antegrade endopyelotomy was performed according to our technique. At the end of the procedure, a nephrostomy tube was positioned, 24F for lithotripsy and 16F for endopyelotomy. The nephrostomy tube was removed after 24 to 48 hours. In this series, 146 patients (15%) presented significant perioperative bleeding. In 97 cases (10%), this complication was resolved with the repositioning of the nephrostomy tube, bedrest in a supine position, and observation, whereas in 49 cases (5%), clamping of the nephrostomy tube for 24 hours was necessary. In 56 patients (5.7%), two blood transfusions were necessary, and three patients (0.3%) had bleeding 10, 12, and 20 days after the operation, which was resolved by embolization of the lacerated vessel. PMID:9895253
Optical coherence tomography findings and retinal changes after vitrectomy for optic disc pit maculopathy
Sanghi, Gaurav; Padhi, Tapas R; Warkad, Vivekanand U; Vazirani, Jayesh; Gupta, Vishali; Dogra, Mangat R; Gupta, Amod; Das, Taraprasad
Purpose: To study the optical coherence tomography (OCT) patterns in optic disc pit maculopathy and retinal changes after vitreous surgery. Materials and Methods: Retrospective review of consecutive cases with optic disc pit maculopathy seen at two tertiary eye institutes from January 2005 to June 2009. Results: Twenty-four eyes of 23 patients are included. The presenting visual acuity ranged from 20/400 to 20/20 (median:20/80). The median age at presentation was 24 years (range, 6-57 years). Optical coherence tomography demonstrated a combination of retinoschisis and outer layer detachment (OLD) in 19 (79.17%) eyes, OLD only in 3 (12.5%) eyes and retinoschisis only in 2 (8.33%) eyes. An obvious communication (outer layer hole) between the schisis and OLD was seen in 14 (73.68%) of the 19 eyes with both features. Of the 21 eyes with retinoschisis, schisis was present in multiple layers in 15 (71.43%) and single layer in 6 (28.57%) eyes. Eleven eyes underwent pars plana vitrectomy including creation of posterior vitreous detachment (PVD), fluid-air exchange, low intensity laser photocoagulation at the temporal edge of the optic disc pit and non-expansile perfluoropropane gas (14%) injection. Five (45.45%) of 11 eyes undergoing vitrectomy had complete resolution and 4 (36.36%) eyes had partial resolution of maculopathy. Visual acuity improved in 8 (72.72%) of 11 eyes. Conclusion: Optical coherence tomography demonstrates multiple layer schisis and outer layer detachment as main features of optic disc pit maculopathy. Vitrectomy with PVD induction, laser photocoagulation and gas tamponade results in anatomical and visual improvement in most cases with optic disc pit maculopathy. PMID:23619493
Adjacent segment disc pressures following two-level cervical disc replacement versus simulated anterior cervical fusion.
Laxer, Eric B; Darden, Bruce V; Murrey, Daniel B; Milam, R Alden; Rhyne, Alfred L; Claytor, Brian; Nussman, Donna S; Powers, Timothy W; Davies, Matthew A; Bryant, S Chad; Larsen, Scott P; Bhatt, Meghal; Brodziak, John; Polic, Jelena
Anterior cervical fusion (ACF) has been shown to alter the biomechanics of adjacent segments of the cervical spine. The goal of total disc replacement is to address pathology at a given disc with minimal disruption of the operated or adjacent segments. This study compares the pressure within discs adjacent to either a two-level simulated ACDF or a two-level total disc replacement with the ProDisc-C. A special automated motion testing apparatus was constructed. Four fresh cadaveric cervical spine specimens were affixed to the test stand and tested in flexion and extension under specific loads. Intradiscal, miniature strain-gauge-based transducers were placed in the discs above and below the "treated" levels. The specimens were then tested in flexion and extension. Pressure and overall angular displacement were measured. In the most extreme and highest quality specimen the difference at C3/C4 registered 800 kPa and the difference at C6/C7 registered 50 kPa. This same quality specimen treated with the ProDisc reached a flexion angle at much lower moments, 24.3 degrees at 5 N-m, when compared to the the SACF 12.2 degrees at 8.6 N-m. Therefore, the moment needed to achieve 15 degrees of flexion with the SACF treatment was 5.5 N-m and the ProDisc treatment was only 2.9 N-m. This initial data would indicate that adjacent level discs experience substantially lower pressure after two-level disc replacement when compared to two-level SACF. Additional testing to further support these observations is ongoing. PMID:17108473
Complex Regional Pain Syndrome Caused by Lumbar Herniated Intervertebral Disc Disease.
Kim, Se Hee; Choi, Sang Sik; Lee, Mi Kyung; Kin, Jung Eun
Most cases of complex regional pain syndrome (CRPS) occur after some inciting injury. There are a few cases of CRPS after an operation for disc disease. CRPS from a mild herniated intervertebral disc (HIVD) without surgical intervention is even rarer than CRPS after an operation for disc disease.A 22-year-old man was transferred to a pain clinic. He had continuously complained about back and right leg pain. He presented with a skin color change in the right lower leg, intermittent resting tremor, stiffness, and swelling in the right leg. He complained of a pulling sensation and numbness in his right buttock, posterior thigh, lateral calf, and ankle. This symptom was in accordance with L4/5 radiculopathy. Magnetic resonance imaging (MRI) also showed L4/5 HIVD that was central to the bilateral subarticular protrusion.He was diagnosed as having CRPS, which fits the revised International Association for the Study of Pain (IASP) criteria. He fulfilled 4 symptom categories (allodynia, temperature asymmetry and skin color change, sweating changes, decreased range of motion and motor dysfunction) and 3 of 4 sign categories (allodynia, temperature asymmetry and skin color changes, decreased range of motion and motor dysfunction). The bone scan and thermography also revealed CRPS.For the past 2 months, we have performed intensive treatments. But, he never became pain-free and walking for 5 minutes led to persistent leg pain. We decided to perform percutaneous nucleoplasty, which can directly decompress a HIVD. On the next day, he achieved dramatic symptom relief. The visual analog scale (VAS) score improved to 3, compared to the VAS score of 9 at the first visit. The skin color change, allodynia, and tremor in the right leg disappeared, and the temperature asymmetry normalized. Motor weakness of the right leg also recovered.We report an unusual case of CRPS that was caused by L4/5 HIVD without a history of trauma or surgery. It has a clear causal relationship between HIVD
Design concepts in lumbar total disc arthroplasty
Bellini, Chiara M.; Zweig, Thomas; Ferguson, Stephen; Raimondi, Manuela T.; Lamartina, Claudio; Brayda-Bruno, Marco; Fornari, Maurizio
The implantation of lumbar disc prostheses based on different design concepts is widely accepted. This paper reviews currently available literature studies on the biomechanics of TDA in the lumbar spine, and is targeted at the evaluation of possible relationships between the aims of TDA and the geometrical, mechanical and material properties of the various available disc prostheses. Both theoretical and experimental studies were analyzed, by a PUBMED search (performed in February 2007, revised in January 2008), focusing on single level TDA. Both semi-constrained and unconstrained lumbar discs seem to be able to restore nearly physiological IAR locations and ROM values. However, both increased and decreased ROM was stated in some papers, unrelated to the clinical outcome. Segmental lordosis alterations after TDA were reported in most cases, for both constrained and unconstrained disc prostheses. An increase in the load through the facet joints was documented, for both semi-constrained and unconstrained artificial discs, but with some contrasting results. Semi-constrained devices may be able to share a greater part of the load, thus protecting the surrounding biological structure from overloading and possible early degeneration, but may be more susceptible to wear. The next level of development will be the biomechanical integration of compression across the motion segment. All these findings need to be supported by long-term clinical outcome studies. PMID:18946684
Crystallization of Self-Propelled Hard Discs.
Briand, G; Dauchot, O
We experimentally study the crystallization of a monolayer of vibrated discs with a built-in polar asymmetry, a model system of active liquids, and contrast it with that of vibrated isotropic discs. Increasing the packing fraction ϕ, the quasicontinuous crystallization reported for isotropic discs is replaced by a transition, or a crossover, towards a "self-melting" crystal. Starting from the liquid phase and increasing the packing fraction, clusters of dense hexagonal-ordered packed discs spontaneously form, melt, split, and merge, leading to a highly intermittent and heterogeneous dynamics. For a packing fraction larger than ϕ^{*}, a few large clusters span the system size. The cluster size distribution is monotonically decreasing for ϕ<ϕ^{*}, nonmonotonic for ϕ>ϕ^{*}, and is a power law at the transition. The system is, however, never dynamically arrested. The clusters permanently melt from place to place, forming droplets of an active liquid which rapidly propagate across the system. This self-melting crystalline state subsists up to the highest possible packing fraction, questioning the stability of the crystal for active discs unless it is at ordered close packing. PMID:27610889
Footprint mismatch in lumbar total disc arthroplasty.
Gstoettner, Michaela; Michaela, Gstoettner; Heider, Denise; Denise, Heider; Liebensteiner, Michael; Bach, Christian Michael; Michael, Bach Christian
Lumbar disc arthroplasty has become a popular modality for the treatment of degenerative disc disease. The dimensions of the implants are based on early published geometrical measurements of vertebrae; the majority of these were cadaver studies. The fit of the prosthesis in the intervertebral space is of utmost importance. An undersized implant may lead to subsidence, loosening and biomechanical failure due to an incorrect center of rotation. The aim of the present study was to measure the dimensions of lumbar vertebrae based on CT scans and assess the accuracy of match in currently available lumbar disc prostheses. A total of 240 endplates of 120 vertebrae were included in the study. The sagittal and mediolateral diameter of the upper and lower endplates were measured using a digital measuring system. For the levels L4/L5 and L5/S1, an inappropriate size match was noted in 98.8% (Prodisc L) and 97.6% (Charite) with regard to the anteroposterior diameter. Mismatch in the anterior mediolateral diameter was noted in 79.3% (Prodisc L) and 51.2% (Charite) while mismatch in the posterior mediolateral diameter was observed in 91.5% (Prodisc L) and 78% (Charite) of the endplates. Surgeons and manufacturers should be aware of the size mismatch of currently available lumbar disc prostheses, which may endanger the safety and efficacy of the procedure. Larger footprints of currently available total disc arthroplasties are required. PMID:18791748
Footprint mismatch in lumbar total disc arthroplasty
Michaela, Gstoettner; Denise, Heider; Liebensteiner, Michael
Lumbar disc arthroplasty has become a popular modality for the treatment of degenerative disc disease. The dimensions of the implants are based on early published geometrical measurements of vertebrae; the majority of these were cadaver studies. The fit of the prosthesis in the intervertebral space is of utmost importance. An undersized implant may lead to subsidence, loosening and biomechanical failure due to an incorrect center of rotation. The aim of the present study was to measure the dimensions of lumbar vertebrae based on CT scans and assess the accuracy of match in currently available lumbar disc prostheses. A total of 240 endplates of 120 vertebrae were included in the study. The sagittal and mediolateral diameter of the upper and lower endplates were measured using a digital measuring system. For the levels L4/L5 and L5/S1, an inappropriate size match was noted in 98.8% (Prodisc L) and 97.6% (Charite) with regard to the anteroposterior diameter. Mismatch in the anterior mediolateral diameter was noted in 79.3% (Prodisc L) and 51.2% (Charite) while mismatch in the posterior mediolateral diameter was observed in 91.5% (Prodisc L) and 78% (Charite) of the endplates. Surgeons and manufacturers should be aware of the size mismatch of currently available lumbar disc prostheses, which may endanger the safety and efficacy of the procedure. Larger footprints of currently available total disc arthroplasties are required. PMID:18791748
Vertical oscillations of fluid and stellar discs
NASA Astrophysics Data System (ADS)
Widrow, Lawrence M.; Bonner, Gage
A satellite galaxy or dark matter subhalo that passes through a stellar disc may excite coherent oscillations in the disc perpendicular to its plane. We determine the properties of these modes for various self-gravitating plane symmetric systems (Spitzer sheets) using the matrix method of Kalnajs. In particular, we find an infinite series of modes for the case of a barotropic fluid. In general, for a collisionless system, there is a double series of modes, which include normal modes and/or Landau-damped oscillations depending on the phase space distribution function of the stars. Even Landau-damped oscillations may decay slowly enough to persist for several hundred Myr. We discuss the implications of these results for the recently discovered vertical perturbations in the kinematics of solar neighbourhood stars and for broader questions surrounding secular phenomena such as spiral structure in disc galaxies.
Laser solidification of injectable scaffolds
NASA Astrophysics Data System (ADS)
Antonov, E. N.; Bagratashvili, V. N.; Borschenko, I. A.; Khlebtsov, B. N.; Khlebtsov, N. G.; Minaeva, S. A.; Popov, V. K.; Popova, A. V.
A novel laser sintering approach of polymer powder and surgical suture material within the cavities has been developed to fabricate biodegradable intra-cavity scaffolds. In the frameworks of such sintering approach, laser radiation is absorbed by the surface of the sintered materials only and cannot damage the surrounding tissue. Our experiments demonstrate the feasibility of fabricated solid intra-cavity polymer structures with a minimally invasive endoscopic technique. This novel approach looks very promising for engineering of spinal discs tissues.
Generation of highly inclined protoplanetary discs through single stellar flybys
NASA Astrophysics Data System (ADS)
Xiang-Gruess, M.
We study the three-dimensional evolution of a viscous protoplanetary disc which is perturbed by a passing star on a parabolic orbit. The aim is to test whether a single stellar flyby is capable to excite significant disc inclinations which would favour the formation of so-called misaligned planets. We use smoothed particle hydrodynamics to study inclination, disc mass and angular momentum changes of the disc for passing stars with different masses. We explore different orbital configurations for the perturber's orbit to find the parameter spaces which allow significant disc inclination generation. Prograde inclined parabolic orbits are most destructive leading to significant disc mass and angular momentum loss. In the remaining disc, the final disc inclination is only below 20°. This is due to the removal of disc particles which have experienced the strongest perturbing effects. Retrograde inclined parabolic orbits are less destructive and can generate disc inclinations up to 60°. The final disc orientation is determined by the precession of the disc angular momentum vector about the perturber's orbital angular momentum vector and by disc orbital inclination changes. We propose a sequence of stellar flybys for the generation of misalignment angles above 60°. The results taken together show that stellar flybys are promising and realistic for the explanation of misaligned Hot Jupiters with misalignment angles up to 60°.
Disc in Flames: Roles of TNF-α and IL-1β in Intervertebral Disc Degeneration
Johnson, Zariel I.; Schoepflin, Zachary R.; Choi, Hyowon; Shapiro, Irving M.; Risbud, Makarand V.
The intervertebral disc is an important mechanical structure that allows range of motion of the spinal column. Degeneration of the intervertebral disc, incited by aging, traumatic insult, genetic predisposition, or other factors, is often defined by functional and structural changes in the tissue, including excessive breakdown of the extracellular matrix, increased disc cell senescence and death, and compromised biomechanical function of the tissue. Intervertebral disc degeneration is strongly correlated with low back pain, which is a highly prevalent and costly condition, significantly contributing to loss in productivity and health care costs. Disc degeneration is a chronic, progressive condition, and current therapies are limited and often focused on symptomatic pain relief rather than curtailing the progression of the disease. Inflammatory processes, exacerbated by cytokines TNF-α and IL-1β are believed to be key mediators of disc degeneration and low back pain. In this review, we describe the contributions of TNF-α and IL-1β to changes seen during disc degeneration at the cellular and tissue level, new evidence suggesting a link between infection of the spine and low back pain, and the emerging therapeutic modalities aimed at combating these processes. PMID:26388614
Effect of intervertebral disc degeneration on disc cell viability: a numerical investigation.
Galbusera, Fabio; Mietsch, Antje; Schmidt, Hendrik; Wilke, Hans-Joachim; Neidlinger-Wilke, Cornelia
Degeneration of the intervertebral disc may be initiated and supported by impairment of the nutrition processes of the disc cells. The effects of degenerative changes on cell nutrition are, however, only partially understood. In this work, a finite volume model was used to investigate the effect of endplate calcification, water loss, reduction of disc height and cyclic mechanical loading on the sustainability of the disc cell population. Oxygen, lactate and glucose diffusion, production and consumption were modelled with non-linear coupled partial differential equations. Oxygen and glucose consumption and lactate production were expressed as a function of local oxygen concentration, pH and cell density. The cell viability criteria were based on local glucose concentration and pH. Considering a disc with normal water content, cell death was initiated in the centre of the nucleus for oxygen, glucose, and lactate diffusivities in the cartilaginous endplate below 20% of the physiological values. The initial cell population could not be sustained even in the non-calcified endplates when a reduction of diffusion inside the disc due to water loss was modelled. Alterations in the disc shape such as height loss, which shortens the transport route between the nutrient sources and the cells, and cyclic mechanical loads, could enhance cell nutrition processes. PMID:21970697
Magnetically driven accretion in protoplanetary discs
NASA Astrophysics Data System (ADS)
Simon, Jacob B.; Lesur, Geoffroy; Kunz, Matthew W.; Armitage, Philip J.
We characterize magnetically driven accretion at radii between 1 and 100 au in protoplanetary discs, using a series of local non-ideal magnetohydrodynamic (MHD) simulations. The simulations assume a minimum mass solar nebula (MMSN) disc that is threaded by a net vertical magnetic field of specified strength. Confirming previous results, we find that the Hall effect has only a modest impact on accretion at 30 au, and essentially none at 100 au. At 1-10 au the Hall effect introduces a pronounced bimodality in the accretion process, with vertical magnetic fields aligned to the disc rotation supporting a strong laminar Maxwell stress that is absent if the field is anti-aligned. In the anti-aligned case, we instead find evidence for bursts of turbulent stress at 5-10 au, which we tentatively identify with the non-axisymmetric Hall-shear instability. The presence or absence of these bursts depends upon the details of the adopted chemical model, which suggests that appreciable regions of actual protoplanetary discs might lie close to the borderline between laminar and turbulent behaviour. Given the number of important control parameters that have already been identified in MHD models, quantitative predictions for disc structure in terms of only radius and accretion rate appear to be difficult. Instead, we identify robust qualitative tests of magnetically driven accretion. These include the presence of turbulence in the outer disc, independent of the orientation of the vertical magnetic fields, and a Hall-mediated bimodality in turbulent properties extending from the region of thermal ionization to 10 au.
Optic disc morphology in pigmentary glaucoma
Jonas, J.; Dichtl, A.; Budde, W.; Lang, P.
AIM—To evaluate the morphology of the optic nerve head in eyes with pigmentary glaucoma. METHODS—Colour stereo optic disc photographs of 62 patients with pigmentary glaucoma and 566 patients with primary open angle glaucoma were morphometrically evaluated. By prestudy selection, mean visual field defect and neuroretinal rim area were not significantly different between the two groups (p=0.89 and p=0.45). RESULTS—The pigmentary glaucoma group did not vary significantly (p >0.10) from the primary open angle glaucoma group in size and shape of the optic disc, configuration of neuroretinal rim, depth of optic cup, area of alpha zone of parapapillary atrophy, diameter of retinal vessels at the disc border, and frequency of disc haemorrhages and localised retinal nerve fibre layer defects. The beta zone of parapapillary atrophy was slightly, but not statistically significantly (p=0.06), smaller in the pigmentary glaucoma group. The mean maximal intraocular pressure and mean intraocular pressure amplitude were significantly (p<0.001) higher in the pigmentary glaucoma group. CONCLUSIONS—In contrast with the characteristic morphology of the anterior segment and despite significantly higher intraocular pressure peaks and a larger pressure amplitude, eyes with pigmentary glaucoma compared with eyes with primary open angle glaucoma do not show a pathognomonic morphology of the optic disc and retinal nerve fibre layer. The slightly smaller beta zone of parapapillary atrophy may correspond to higher intraocular pressure in pigmentary glaucoma. Keywords: optic disc morphology; pigmentary glaucoma; secondary open angle glaucoma PMID:9828769
Appearance of Keplerian discs orbiting Kerr superspinars
NASA Astrophysics Data System (ADS)
Stuchlík, Zdeněk; Schee, Jan
We study optical phenomena related to the appearance of Keplerian accretion discs orbiting Kerr superspinars predicted by string theory. The superspinar exterior is described by standard Kerr naked singularity geometry breaking the black hole limit on the internal angular momentum (spin). We construct local photon escape cones for a variety of orbiting sources that enable us to determine the superspinars silhouette in the case of distant observers. We show that the superspinar silhouette depends strongly on the assumed edge where the external Kerr spacetime is joined to the internal spacetime governed by string theory and significantly differs from the black hole silhouette. The appearance of the accretion disc is strongly dependent on the value of the superspinar spin in both their shape and frequency shift profile. Apparent extension of the disc grows significantly with the growing spin, while the frequency shift grows with the descending spin. This behaviour differs substantially from the appearance of discs orbiting black holes enabling thus, at least in principle, to distinguish clearly the Kerr superspinars and black holes. In vicinity of a Kerr superspinar the non-escaped photons have to be separated to those captured by the superspinar and those being trapped in its strong gravitational field leading to self-illumination of the disc that could even influence its structure and cause self-reflection effect of radiation of the disc. The amount of trapped photons grows with descending superspinar spin. We thus can expect significant self-illumination effects in the field of Kerr superspinars with near-extreme spin a ~ 1.
Single puncture percutaneous nephrolithomy for management of complex renal stones
Shalaby, Mahmoud M; Abdalla, Medhat A; Aboul-Ella, Hassan A; El-haggagy, Abdel-Monem A; Abd-Elsayed, Alaa A
Background The purpose of this report is to assess the safety and efficacy of single lower pole access for multiple and branched renal calculi. A prospective non randomized clinical study included 26 patients with complex renal stones (9 patients had branched renal stones and the other 17 had multiple renal stones) in the period from May 2003 to May 2004. Mean patient age was 42 years ± 13.2 (range 18 to 67 years). All patients underwent percutaneous nephrolithotomy (PCNL) via a single lower calyceal puncture. Small stones were intactly extracted by a range of stone graspers while large stones (smallest diameter more than 1 cm) were disintegrated using either the pneumatic EMS Swiss lithoclast or Holmium YAG laser. Flexible nephroscope was used for stones inaccessible by the rigid instruments. Findings Overall stone-free rate was 74.8%. Patients with residual stones were managed by one session of shock wave lithotripsy (SWL). Mean operative time was (80 minutes ± 27.4) for branched stones and (49.1 minutes ± 15.9) for multiple stones. No significant blood loss reported. Perforation of pelvicalyceal system occurred in 2 patients (11.5%) with no serious sequelae. Only 1 patient developed secondary hemorrhage which necessitated blood transfusion and selective angio-embolization. Conclusion In our hands, the efficacy and safety of single lower calyceal puncture PCNL in management of complex renal stones are comparable to those of the general procedure stated in literature. PMID:19379503
Null generation using discs on a reflector
NASA Astrophysics Data System (ADS)
Rudisill, M. D.
It has been shown possible experimentally to produce nulls in the pattern of a prime focus reflector antenna using discs mounted on the dish. A model of this antenna system is developed to evaluate optimal configurations and ideal performance. Aperture integration is the method of analysis used. Discs' effects are modeled as a phase shift on the aperture. No secondary effects, such as diffraction, are considered. Based on the model developed, guidelines are presented for antenna design. A computer code was written to implement the model and a prediction of antenna the system's performance is presented.
Disc valve for sampling erosive process streams
Mrochek, J.E.; Dinsmore, S.R.; Chandler, E.W.
A four-port disc valve is described for sampling erosive, high temperature process streams. A rotatable disc defining opposed first and second sampling cavities rotates between fired faceplates defining flow passageways positioned to be alternatively in axial alignment with the first and second cavities. Silicon carbide inserts and liners composed of [alpha] silicon carbide are provided in the faceplates and in the sampling cavities to limit erosion while providing lubricity for a smooth and precise operation when used under harsh process conditions. 1 fig.
Two-level total lumbar disc replacement
Bakaloudis, Georgios; Lolli, Francesco; Vommaro, Francesco; Parisini, Patrizio
Total lumbar disc replacement (TDR) has been widely used as a treatment option for 2-level symptomatic degenerative disc disease. However, recent studies have presented conflicting results and some authors concluded that outcome deteriorated when disc replacement was performed bisegmentally, with an increase of complications for bisegmental replacements in comparison with monosegmental disc arthroplasty. The goal of the present retrospective study is to investigate results in a group of patients who have received bisegmental TDR with SB Charitè III artificial disc for degenerative disc disease with a minimum follow-up of 3 years, and to compare the results of 2-level disc replacement versus 1-level patients treated with the same prosthesis. A total of 32 patients had at least 3-years follow-up and were reviewed. The average age of the patients was 38.5 years. There were 11 males and 21 females. About 16 patients received 2-level TDR (SB Charitè III) and 16 received 1-level TDR (SB Charitè III). Both radiographic and functional outcome analysis, including patient's satisfaction, was performed. There were no signs of degenerative changes of the adjacent segments in any case of the 2- or 1-level TDR. There was no statistically significant difference between 2- and 1-level TDR both at 12 months and at 3-years follow-up on functional outcome scores. There was a statistically insignificant difference concerning the patients satisfaction between 1- and 2-level surgeries at the last follow-up (P = 0.46). In the 2-level TDR patients, there were 5 minor complications (31.25%), whereas major complications occurred in 4 more patients (25%) and required a new surgery in 2 cases (12.5%). In the 1-level cases there were 2 minor complications (12.5%) and 2 major complications (12.5%) and a new revision surgery was required in 1 patient (6.25%). In conclusion, the use of 2-level disc replacement at last follow-up presented a higher incidence of complications than in cases
Progression of a lumbar disc extrusion.
Crowell, Michael S; Alitz, Curtis
The patient was a 34-year-old woman who was referred to a physical therapist for a chief complaint of progressively worsening right buttock pain with paresthesias of the right posterior thigh and calf. Prior magnetic resonance imaging of the patient's lumbar spine revealed a large left paracentral disc extrusion at L5-S1. Following physical therapist intervention, the patient reported a new onset of left posterior thigh pain, with paresthesias of the dorsolateral aspect of the left foot. Repeat magnetic resonance imaging of the patient's lumbar spine revealed an increase in the size of the disc extrusion at L5-S1. PMID:25361862
Acute endocarditis of a percutaneously placed pulmonary valve
Ramakrishnan, Karthik V; Olivieri, Laura; Jonas, Richard A
Endocarditis of percutaneously placed pulmonary valve is increasingly being recognized and reported as a potentially life-threatening complication. In this report, we discuss a 17-year-old male who presented with septic shock secondary to staphylococcal endocarditis of a percutaneously placed pulmonary valve. PMID:26556969
Percutaneous feeding tube method for use in children.
Long, B; Rafert, J; Cory, D
Surgical gastrostomy has been a widely accepted method for introducing a percutaneous feeding tube for many years. However, complications are frequent, and many children who need them are not good surgical candidates. This study examines imaging guided percutaneous placement of feeding gastrostomy catheters as a safe and effective alternative to surgery. PMID:1902957
Percutaneous transluminal angioplasty of radiation-induced arterial stenoses
Guthaner, D.F.; Schmitz, L.
A case of atherosclerosis resulting from previous irradiation was successfully treated using percutaneous transluminal angioplasty for recanalization of the vessel. Irradiation may result in extensive perivascular fibrosis around an area of arterial narrowing; percutaneous transluminal angioplasty appears to be the method of choice for treatment of such lesions.
Percutaneous Sclerotherapy With OK-432 of a Cervicomediastinal Lymphangioma.
Golinelli, Gloria; Toso, Andrea; Borello, Giovanni; Aluffi, Paolo; Pia, Francesco
The present study reports a case of percutaneous sclerotherapy of a giant cystic cervicomediastinal lymphangioma using OK-432. To the best of our knowledge, percutaneous sclerotherapy of a mediastinal lymphangioma using OK 432 has not previously been reported in the English literature. PMID:26522530
Percutaneous Balloon Compression vs Percutaneous Retrogasserian Glycerol Rhizotomy for the Primary Treatment of Trigeminal Neuralgia
Blomstedt, Patric; Bergenheim, A. Tommy
BACKGROUND: Despite >30 years of clinical use, the literature is still sparse when it comes to comparisons between percutaneous balloon compression (PBC) and percutaneous retrogasserian glycerol rhizolysis (PRGR) as treatments for trigeminal neuralgia. OBJECTIVE: To perform a retrospective cohort comparison between PBC and PRGR with regard to therapeutic effect, side effects, and complications. METHODS: Medical records and follow-up data from 124 primary PRGRs performed from 1986 to 2000 and 82 primary PBCs performed from 2000 to 2013 were reviewed. All patients had undergone clinical sensory testing and assessment of sensory thresholds. Analyses were performed to compare duration of pain relief, frequency of sensory disturbances, and side effects. RESULTS: Median duration of pain relief was 21 months after PRGR and 20 months after PBC. Both methods carried a high risk of hypesthesia/hypalgesia (P < .001) that was partly reversed with time. Decreased corneal sensibility was common after PRGR (P < .001) but not after PBC. Dysesthesia was more common after PRGR (23%) compared after PBC (4%; P < .001). Other side effects were noted but uncommon. CONCLUSION: PBC and PRGR are both effective as primary surgical treatment of trigeminal neuralgia. Both carry a risk of postoperative hypesthesia, but in this series, the side effect profile favored PBC. Furthermore, PBC is technically less challenging, whereas PRGR requires fewer resources. Between these 2 techniques, we propose PBC as the primary surgical technique for percutaneous treatment of trigeminal neuralgia on the basis of its lower incidence of dysesthesia, corneal hypesthesia, and technical failures. ABBREVIATIONS: MS, multiple sclerosis PBC, percutaneous balloon compression PRGR, percutaneous retrogasserian glycerol rhizotomy TN, trigeminal neuralgia PMID:26465639
Lasers in Cardiovascular Surgery—Current Status
Hunter, John G.; Dixon, John A.
The argon, carbon dioxide and neodymium-YAG lasers have been proposed as effective instruments for surgical procedures of the intact cardiovascular system. While argon and CO2 lasers cause superficial (0 to 1 mm) thermal injury, the Nd:YAG laser is better suited for effecting deep thermal necrosis (3 to 4 mm). Microsurgical vessel anastomoses can be done by "tissue welding" with any of the three clinical lasers. Myocardial revascularization may be accomplished by drilling "neocapillaries" in ischemic myocardium. Endocardial resection for destroying arrhythmic pathways and removing hypertrophied septal muscle has also been successfully accomplished with laser phototherapy. Last, laser-mediated vaporization of atherosclerotic plaque in the coronary arteries and peripheral circulation may offer a percutaneous approach to the treatment of arterial occlusive disease. Cardiovascular uses of lasers are purely investigational at the current time. Much more needs to be known before widespread clinical use of lasers in the cardiovascular system can occur. PMID:3160168
Percutaneous Mitral Annuloplasty for Functional Mitral Regurgitation
Schofer, Joachim; Siminiak, Tomasz; Haude, Michael; Herrman, Jean P.; Vainer, Jindra; Wu, Justina C.; Levy, Wayne C.; Mauri, Laura; Feldman, Ted; Kwong, Raymond Y.; Kaye, David M.; Duffy, Stephen J.; Tübler, Thilo; Degen, Hubertus; Brandt, Mathias C.; Van Bibber, Rich; Goldberg, Steve; Reuter, David G.; Hoppe, Uta C.
Background Functional mitral regurgitation (FMR), a well-recognized component of left ventricular remodeling, is associated with increased morbidity and mortality in heart failure patients. Percutaneous mitral annuloplasty has the potential to serve as a therapeutic adjunct to standard medical care. Methods and Results Patients with dilated cardiomyopathy, moderate to severe FMR, an ejection fraction <40%, and a 6-minute walk distance between 150 and 450 m were enrolled in the CARILLON Mitral Annuloplasty Device European Union Study (AMADEUS). Percutaneous mitral annuloplasty was achieved through the coronary sinus with the CARILLON Mitral Contour System. Echocardiographic FMR grade, exercise tolerance, New York Heart Association class, and quality of life were assessed at baseline and 1 and 6 months. Of the 48 patients enrolled in the trial, 30 received the CARILLON device. Eighteen patients did not receive a device because of access issues, insufficient acute FMR reduction, or coronary artery compromise. The major adverse event rate was 13% at 30 days. At 6 months, the degree of FMR reduction among 5 different quantitative echocardiographic measures ranged from 22% to 32%. Six-minute walk distance improved from 307±87 m at baseline to 403±137 m at 6 months (P<0.001). Quality of life, measured by the Kansas City Cardiomyopathy Questionnaire, improved from 47±16 points at baseline to 69±15 points at 6 months (P<0.001). Conclusions Percutaneous reduction in FMR with a novel coronary sinus–based mitral annuloplasty device is feasible in patients with heart failure, is associated with a low rate of major adverse events, and is associated with improvement in quality of life and exercise tolerance. PMID:19597051
Orthopedic surgical analyzer for percutaneous vertebroplasty
NASA Astrophysics Data System (ADS)
Tack, Gye Rae; Choi, Hyung Guen; Lim, Do H.; Lee, Sung J.
Since the spine is one of the most complex joint structures in the human body, its surgical treatment requires careful planning and high degree of precision to avoid any unwanted neurological compromises. In addition, comprehensive biomechanical analysis can be very helpful because the spine is subject to a variety of load. In case for the osteoporotic spine in which the structural integrity has been compromised, it brings out the double challenges for a surgeon both clinically and biomechanically. Thus, we have been developing an integrated medical image system that is capable of doing the both. This system is called orthopedic surgical analyzer and it combines the clinical results from image-guided examination and the biomechanical data from finite element analysis. In order to demonstrate its feasibility, this system was applied to percutaneous vertebroplasty. Percutaneous vertebroplasty is a surgical procedure that has been recently introduced for the treatment of compression fracture of the osteoporotic vertebrae. It involves puncturing vertebrae and filling with polymethylmethacrylate (PMMA). Recent studies have shown that the procedure could provide structural reinforcement for the osteoporotic vertebrae while being minimally invasive and safe with immediate pain relief. However, treatment failures due to excessive PMMA volume injection have been reported as one of complications. It is believed that control of PMMA volume is one of the most critical factors that can reduce the incidence of complications. Since the degree of the osteoporosis can influence the porosity of the cancellous bone in the vertebral body, the injection volume can be different from patient to patient. In this study, the optimal volume of PMMA injection for vertebroplasty was predicted based on the image analysis of a given patient. In addition, biomechanical effects due to the changes in PMMA volume and bone mineral density (BMD) level were investigated by constructing clinically
Compact Discs--A Revolution in the Making.
ERIC Educational Resources Information Center
Ridgway, Jim
Discusses the theory behind the system of the compact disc (encoding process, decoding system), its potential for growth, and its possible impact on the way libraries handle sound recordings. Guidelines for purchase of compact disc equipment are given. A comparison of compact discs and long-playing records is appended. (37 references) (EJS)
The Effects of Simulated Microgravity on Intervertebral Disc Degeneration
Jin, Li; Feng, Gang; Reames, Davis L; Shimer, Adam L; Shen, Francis H; Li, Xudong
BACKGROUND CONTEXT Astronauts experience back pain, particularly low back pain, during and after spaceflight. Recent studies have described histological and biochemical changes in rat intervertebral discs after space travel, but there is still no in vitro model to investigate the effects of microgravity on disc metabolism. PURPOSE To study the effects of microgravity on disc degeneration and to establish an in vitro simulated microgravity study model STUDY DESIGN Discs were cultured in static and rotating conditions in bioreactor, and the characteristics of disc degeneration were evaluated METHODS The mice discs were cultured in a rotating wall vessel bioreactor where the microgravity condition was simulated. Intervertebral discs were cultured in static and microgravity condition. Histology, biochemistry, and immunohistochemical assays were performed to evaluate the characteristics of the discs in microgravity condition. RESULTS Intervertebral discs cultured in rotating bioreactors were found to develop changes of disc degeneration manifested by reduced red Safranin-o staining within the annulus fibrosus, downregulated GAG content and GAG/Hypro ratio, increased MMP-3 expression, and upregulated apoptosis. CONCLUSIONS We conclude that simulated microgravity induces the molecular changes of disc degeneration. The rotating bioreactor model will provide a foundation to investigate the effects of microgravity on disc metabolism. PMID:23537452
Phase plate technology for laser marking of magnetic discs
Neuman, B.; Honig, J.; Hackel, L.; Dane, C.B.; Dixit, S.
An advanced design for a phase plate enables the distribution of spots in arbitrarily shaped patterns with very high uniformity and with a continuously or near-continuously varying phase pattern. A continuous phase pattern eliminates large phase jumps typically expected in a grating that provides arbitrary shapes. Large phase jumps increase scattered light outside of the desired pattern, reduce efficiency and can make the grating difficult to manufacture. When manufacturing capabilities preclude producing a fully continuous grating, the present design can be easily adapted to minimize manufacturing errors and maintain high efficiencies. This continuous grating is significantly more efficient than previously described Dammann gratings, offers much more flexibility in generating spot patterns and is easier to manufacture and replicate than a multi-level phase grating. 3 figs.
Phase plate technology for laser marking of magnetic discs
Neuman, Bill; Honig, John; Hackel, Lloyd; Dane, C. Brent; Dixit, Shamasundar
An advanced design for a phase plate enables the distribution of spots in arbitrarily shaped patterns with very high uniformity and with a continuously or near-continuously varying phase pattern. A continuous phase pattern eliminates large phase jumps typically expected in a grating that provides arbitrary shapes. Large phase jumps increase scattered light outside of the desired pattern, reduce efficiency and can make the grating difficult to manufacture. When manufacturing capabilities preclude producing a fully continuous grating, the present design can be easily adapted to minimize manufacturing errors and maintain high efficiencies. This continuous grating is significantly more efficient than previously described Dammann gratings, offers much more flexibility in generating spot patterns and is easier to manufacture and replicate than a multi-level phase grating.
Percutaneous nephrolithotomy and ureteroscopy in children: evolutions.
Long, Christopher J; Srinivasan, Arun K
The increasing incidence of pediatric stone disease has coincided with significant advances in technology and equipment, resulting in drastic improvements in management. Miniaturization of both ureteroscopes and percutaneous nephrolithotomy (PCNL) equipment has facilitated access to the entirety of the urinary tract and has made ureteroscopy a first-line therapy option along with shock-wave lithotripsy for kidney and ureteral stones. Advances in PCNL have decreased patient morbidity while preserving stone clearance rates. In this review, the advances in operative approach for ureteroscopy and PCNL in children and its applicability to current surgical management of pediatric stone disease are discussed. PMID:25455168
Percutaneous Cryoablation and Vertebroplasty: A Case Report
Masala, Salvatore; Roselli, Mario; Manenti, Guglielmo; Mammucari, Matteo; Bartolucci, Dario Alberto Simonetti, Giovanni
A 70-year-old man with a painful vertebral metastasis was treated with combined percutaneous cryoablation and vertebroplasty therapy (CVT) in one session. The patient was suffering from diffuse visceral metastasized cholangiocarcinoma. After several weeks of back pain, magnetic resonance imaging documented a single L2 bone metastasis. In consultation with the oncologists, palliative combined CVT was administered with the aim of obtaining pain relief and bone stabilization. In our experience this combined treatment is safe and effective for immediate pain relief in painful bone metastases when other standard palliative treatments have failed.
PET-Based Percutaneous Needle Biopsy.
El-Haddad, Ghassan
PET can be used to guide percutaneous needle biopsy to the most metabolic lesion, improving diagnostic yield. PET biopsy guidance can be performed using visual or software coregistration, electromagnetic needle tracking, cone-beam computed tomography (CT), and intraprocedural PET/CT guidance. PET/CT-guided biopsies allow the sampling of lesions that may not be clearly visible on anatomic imaging, or of lesions that are morphologically normal. PET can identify suspicious locations within complex tumors that are most likely to contain important diagnostic and prognostic information. PMID:27321036
Percutaneous cryoablation and vertebroplasty: a case report.
Masala, Salvatore; Roselli, Mario; Manenti, Guglielmo; Mammucari, Matteo; Bartolucci, Dario Alberto; Simonetti, Giovanni
A 70-year-old man with a painful vertebral metastasis was treated with combined percutaneous cryoablation and vertebroplasty therapy (CVT) in one session. The patient was suffering from diffuse visceral metastasized cholangiocarcinoma. After several weeks of back pain, magnetic resonance imaging documented a single L2 bone metastasis. In consultation with the oncologists, palliative combined CVT was administered with the aim of obtaining pain relief and bone stabilization. In our experience this combined treatment is safe and effective for immediate pain relief in painful bone metastases when other standard palliative treatments have failed. PMID:18459032
Direct Percutaneous Embolization of Bleeding Stomal Varices
Naidu, Sailen G.; Castle, Erik P.; Kriegshauser, J. Scott; Huettl, Eric A.
Stomal variceal bleeding can develop in patients with underlying cirrhosis and portal hypertension. Most patients are best treated with transjugular intrahepatic portosystemic shunt (TIPS) creation because this addresses the underlying problem of portal hypertension. However, some patients are not good candidates for TIPS creation because they have end-stage liver disease or encephalopathy. We describe such a patient who presented with recurrent bleeding stomal varices, which was successfully treated with percutaneous coil embolization. The patient had bleeding-free survival for 1 month before death from unrelated causes.
Reappraisal of the ratio of disc to macula/disc diameter in optic nerve hypoplasia.
Zeki, S M; Dudgeon, J; Dutton, G N
The ratio of disc to macula/disc diameter is characteristically increased in eyes with optic nerve hypoplasia. We present the largest reported series of patients with a definitive diagnosis of optic nerve hypoplasia for whom this ratio has been determined. All measurements were made by an independent masked observer. Our results are in accordance with previous reports. A ratio of 2.94 provides a one-tailed upper population limit of 95%. An attempt has been made to correlate optic disc size and visual acuity. In 75% of bilateral cases the eye with the relatively smaller optic disc was found to have a better Snellen visual acuity than the fellow eye. This suggests that additional pathogenic mechanism(s) may have determined the eventual visual outcome in such eyes. Such mechanisms include macular hypoplasia, high refractive error, refractive amblyopia, central scotoma, and optic atrophy. Images PMID:1911656
Prognosis of intervertebral disc loss from diagnosis of degenerative disc disease
NASA Astrophysics Data System (ADS)
Li, S.; Lin, A.; Tay, K.; Romano, W.; Osman, Said
Degenerative Disc Disease (DDD) is one of the most common causes of low back pain, and is a major factor in limiting the quality of life of an individual usually as they enter older stages of life, the disc degeneration reduces the shock absorption available which in turn causes pain. Disc loss is one of the central processes in the pathogenesis of DDD. In this study, we investigated whether the image texture features quantified from magnetic resonance imaging (MRI) could be appropriate markers for diagnosis of DDD and prognosis of inter-vertebral disc loss. The main objective is to use simple image based biomarkers to perform prognosis of spinal diseases using non-invasive procedures. Our results from 65 subjects proved the higher success rates of the combination marker compared to the individual markers and in the future, we will extend the study to other spine regions to allow prognosis and diagnosis of DDD for a wider region.
Analog disc recorder system: operator's reference manual
O'Brien, J.D.; Smith, E.L.
The FM Analog Disc Recorder System is a cost-efficient means of capturing analog transient data from many channels; it has high-frequency response and long record time. It can digitize recorded signals, correct internal distortion, and present the data as plots either on a CRT, hardcopy plot, or both. The system is easy to use, self-contained, and compact.
Compact Disc Cataloging Product User Survey.
ERIC Educational Resources Information Center
Whitehair, David E.
In late 1988, a compact disc cataloging product was introduced to the library market. In order to learn more about the needs of current users, a survey was developed to include questions concerning software features and operations, software enhancements, bibliographic and authority subsets, and hardware issues. This study was conducted among all…
Periodic dynamics of pairs of sedimenting discs
NASA Astrophysics Data System (ADS)
Chajwa, Rahul; Menon, Narayanan; Ramaswamy, Sriram
We study the sedimentation in the Stokes regime of pairs of discs released with a variety of orientations relative to each other and to gravity. The orientation of a settling disk is coupled with the translational degree of freedom. Hydrodynamic interactions between settling disks produces richer dynamics than is possible with sedimenting spheres. We demonstrate the classes of dynamics that follow from a variety of initial conditions, but focus on the periodic oscillations in position and orientation that result when two discs are released parallel to each other with their normals coaxial and in the horizontal plane. We report experiments that study the frequency, wavelength, and amplitude of the periodic flutter as a function of initial separation between the discs. We analyze the motions within a model that combines the hydrodynamics of single discs with a simplified model of their interaction that includes low order terms of appropriate symmetry. This allows us to examine the initial conditions that demarcate periodic from non-periodic dynamics. Also at Dept of Physics and Astronomy, Univ of Massachusetts, Amherst MA 01003.
Microarray technology as applied to areas that include genomics, diagnostics, environmental, and drug discovery, is an interesting research topic for which different chip-based devices have been developed. As an alternative, we have explored the principle of compact disc-based...
Optical Disc Technology for Information Management.
ERIC Educational Resources Information Center
Brumm, Eugenia K.
This summary of the literature on document image processing from 1988-90 focuses on WORM (write once read many) technology and on rewritable (i.e., erasable) optical discs, and excludes CD-ROM. Highlights include vendors and products, standards, comparisons of storage media, software, legal issues, records management, indexing, and computer…
Disc valve for sampling erosive process streams
Mrochek, J.E.; Dinsmore, S.R.; Chandler, E.W.
This is a patent for a disc-type, four-port sampling valve for service with erosive high temperature process streams. Inserts and liners of ..cap alpha..-silicon carbide respectively, in the faceplates and in the sampling cavities, limit erosion while providing lubricity for a smooth and precise operation. 1 fig.
Training Endusers on MathSci Disc.
ERIC Educational Resources Information Center
Sichel, Beatrice
Describes how the physical sciences library at Western Michigan University introduced a mathematical database on CD-ROM and trained patrons to conduct their own searches. The "Mathematical Reviews" database (entitled MathSci Disc) is described, and three types of training are discussed: informal demonstrations, self-instructional guides, and…
Frictional Torque on a Rotating Disc
ERIC Educational Resources Information Center
Mungan, Carl E.
Resistance to motion often includes a dry frictional term independent of the speed of an object and a fluid drag term varying linearly with speed in the viscous limit. (At higher speeds, quadratic drag can also occur.) Here, measurements are performed for an aluminium disc mounted on bearings that is given an initial twist and allowed to spin…
On the convective overstability in protoplanetary discs
NASA Astrophysics Data System (ADS)
Latter, Henrik N.
This paper explores the driving of low-level hydrodynamical activity in protoplanetary-disc dead zones. A small adverse radial entropy gradient, ordinarily stabilized by rotation, excites oscillatory convection (`convective overstability') when thermal diffusion, or cooling, is neither too strong nor too weak. I revisit the linear theory of the instability, discuss its prevalence in protoplanetary discs, and show that unstable modes are exact non-linear solutions in the local Boussinesq limit. Overstable modes cannot grow indefinitely, however, as they are subject to a secondary parametric instability that limits their amplitudes to relatively low levels. If parasites set the saturation level of the ensuing turbulence then the convective overstability is probably too weak to drive significant angular momentum transport or to generate vortices. But I also discuss an alternative, and far more vigorous, saturation route that generates radial `layers' or `zonal flows' (witnessed in semiconvection). Numerical simulations are required to determine which outcome is favoured in realistic discs, and consequently how important the instability is for disc dynamics.
Evolution of gas in debris discs
NASA Astrophysics Data System (ADS)
Kral, Quentin; Wyatt, Mark; Pringle, Jim
A non negligible quantity of gas has been discovered in an increasing number of debris disc systems. ALMA high sensitivity and high resolution is changing our perception of the gaseous component of debris discs as CO is discovered in systems where it should be rapidly photodissociated. It implies that there is a replenishment mechanism and that the observed gas is secondary. Past missions such as Herschel probed the atomic part of the gas through O I and C II emission lines. Gas science in debris discs is still in its infancy, and these new observations raise a handful of questions concerning the mechanisms to create the gas and about its evolution in the planetary system when it is released. The latter question will be addressed in this talk as a self-consistent gas evolution scenario is proposed and is compared to observations for the peculiar case of β Pictoris.Our model proposes that carbon and oxygen within debris discs are created due to photodissociation of CO which is itself created from the debris disc dust (due to grain-grain collisions or photodesorption). The evolution of the carbon atoms is modelled as viscous spreading, with viscosity parameterised using an α model. The temperature, ionisation fraction and population levels of carbon are followed with a PDR model called Cloudy, which is coupled to the dynamical viscous α model. Only carbon gets ionised due to its lower ionisation potential than oxygen. The carbon gas disc can end up with a high ionisation fraction due to strong FUV radiation field. A high ionisation fraction means that the magnetorotational instability (MRI) is very active, so that α is very high. Gas density profiles can be worked out for different input parameters such as the α value, the CO input rate, the location of the input and the incoming radiation field. Observability predictions can be made for future observations, and our model is tested on β Pictoris observations. This new gas evolution model fits the carbon and CO
Grain size segregation in debris discs
NASA Astrophysics Data System (ADS)
Thebault, P.; Kral, Q.; Augereau, J.-C.
Context. In most debris discs, dust grain dynamics is strongly affected by stellar radiation pressure. Because this mechanism is size-dependent, we expect dust grains to be spatially segregated according to their sizes. However, because of the complex interplay between radiation pressure, grain processing by collisions, and dynamical perturbations, this spatial segregation of the particle size distribution (PSD) has proven difficult to investigate and quantify with numerical models. Aims: We propose to thoroughly investigate this problem by using a new-generation code that can handle some of the complex coupling between dynamical and collisional effects. We intend to explore how PSDs behave in both unperturbed discs at rest and in discs pertubed by planetary objects. Methods: We used the DyCoSS code to investigate the coupled effect of collisions, radiation pressure, and dynamical perturbations in systems that have reached a steady-state. We considered two setups: a narrow ring perturbed by an exterior planet, and an extended disc into which a planet is embedded. For both setups we considered an additional unperturbed case without a planet. We also investigated the effect of possible spatial size segregation on disc images at different wavelengths. Results: We find that PSDs are always spatially segregated. The only case for which the PSD follows a standard dn ∝ s-3.5ds law is for an unperturbed narrow ring, but only within the parent-body ring itself. For all other configurations, the size distributions can strongly depart from such power laws and have steep spatial gradients. As an example, the geometrical cross-section of the disc is very rarely dominated by the smallest grains on bound orbits, as it is expected to be in standard PSDs in sq with q ≤ -3. Although the exact profiles and spatial variations of PSDs are a complex function of the set-up that is considered, we are still able to derive some reliable results that will be useful for image or SED
Clinical and Radiological Characteristics of Lumbosacral Lateral Disc Herniation in Comparison With Those of Medial Disc Herniation
Lee, Jung Hwan; Lee, Sang-Ho
Abstract Lateral disc herniation (foraminal and extra foraminal) has clinical characteristics that are different from those of medial disc herniation (central and subarticular), including older age, more frequent radicular pain, and neurologic deficits. This is supposedly because lateral disc herniation mechanically irritates or compresses the exiting nerve root or dorsal root ganglion inside of a narrow canal more directly than medial disc herniation. The purpose of this study was to investigate clinical and radiological characteristics of lateral disc herniation in comparison with medial disc herniation. The 352 subjects diagnosed with localized lumbosacral disc herniation and followed up for at least 12 months after completion of treatment were included and divided into medial and lateral disc herniation groups, according to the anatomical location of the herniated disc in axial plain of magnetic resonance image. Clinical and radiological data were obtained and compared between the two groups. The lateral group included 74 (21%) patients and the medial group included 278 (79%). Mean age of the lateral group was significantly higher than that in the medial group. The lateral group showed a significantly larger proportion of patients with radiating leg pain and multiple levels of disc herniations than the medial group. No significant differences were found in terms of gender, duration of pain, pretreatment numeric rating scale, severity of disc herniation (protrusion and extrusion), and presence of weakness in leg muscles. The proportion of patients who underwent surgery was not significantly different between the 2 groups. However, the proportion of patients who accomplished successful pain reduction after treatment was significantly smaller in the lateral than in the medial group. In conclusion, patients with lateral disc herniation were older and had larger proportion of radiating leg pain than those with medial disc herniation. Lateral disc herniation was more
Clinical and Radiological Characteristics of Lumbosacral Lateral Disc Herniation in Comparison With Those of Medial Disc Herniation.
Lee, Jung Hwan; Lee, Sang-Ho
Lateral disc herniation (foraminal and extra foraminal) has clinical characteristics that are different from those of medial disc herniation (central and subarticular), including older age, more frequent radicular pain, and neurologic deficits. This is supposedly because lateral disc herniation mechanically irritates or compresses the exiting nerve root or dorsal root ganglion inside of a narrow canal more directly than medial disc herniation. The purpose of this study was to investigate clinical and radiological characteristics of lateral disc herniation in comparison with medial disc herniation. The 352 subjects diagnosed with localized lumbosacral disc herniation and followed up for at least 12 months after completion of treatment were included and divided into medial and lateral disc herniation groups, according to the anatomical location of the herniated disc in axial plain of magnetic resonance image. Clinical and radiological data were obtained and compared between the two groups. The lateral group included 74 (21%) patients and the medial group included 278 (79%). Mean age of the lateral group was significantly higher than that in the medial group. The lateral group showed a significantly larger proportion of patients with radiating leg pain and multiple levels of disc herniations than the medial group. No significant differences were found in terms of gender, duration of pain, pretreatment numeric rating scale, severity of disc herniation (protrusion and extrusion), and presence of weakness in leg muscles. The proportion of patients who underwent surgery was not significantly different between the 2 groups. However, the proportion of patients who accomplished successful pain reduction after treatment was significantly smaller in the lateral than in the medial group. In conclusion, patients with lateral disc herniation were older and had larger proportion of radiating leg pain than those with medial disc herniation. Lateral disc herniation was more
Percutaneous Endoscopic Lumbar Foraminotomy: An Advanced Surgical Technique and Clinical Outcomes
Oh, Hyun-Kyong; Kim, Ho; Lee, Sang-Ho; Lee, Haeng-Nam
BACKGROUND: Although several authors have reported the use of endoscopic techniques to treat lumbar foraminal stenosis, the practical application of these techniques has been limited to soft disc herniation. OBJECTIVE: To describe the details of the percutaneous endoscopic lumbar foraminotomy (ELF) technique for bony foraminal stenosis and to demonstrate the clinical outcomes. METHODS: Two years of prospective data were collected from 33 consecutive patients with lumbar foraminal stenosis who underwent ELF. The surgical outcomes were assessed using the visual analog scale, Oswestry Disability Index, and modified MacNab criteria. The procedure begins at the safer extraforaminal zone rather than the riskier intraforaminal zone. Then, a full-scale foraminal decompression can be performed using a burr and punches under endoscopic control. RESULTS: The mean age of the 18 female and 15 male patients was 64.2 years. The mean visual analog scale score for leg pain improved from 8.36 at baseline to 3.36 at 6 weeks, 2.03 at 1 year, and 1.97 at 2 years post-surgery (P < .001). The mean Oswestry Disability Index improved from 65.8 at baseline to 31.6 at 6 weeks, 19.7 at 1 year, and 19.3 at 2 years post-surgery (P < .001). Based on the modified MacNab criteria, excellent or good results were obtained in 81.8% of the patients, and symptomatic improvements were obtained in 93.9%. CONCLUSION: Percutaneous ELF under local anesthesia could be an efficacious surgical procedure for the treatment of foraminal stenosis. This procedure may offer safe and reproducible results, especially for elderly or medically compromised patients. ABBREVIATIONS: ELF,endoscopic lumbar foraminotomy ODI, Oswestry Disability Index VAS, visual analog scale PMID:24691470
Enhancement of Overgrowth by Gene Interactions in Lethal(2)giant Discs Imaginal Discs from Drosophila Melanogaster
Buratovich, M. A.; Bryant, P. J.
Recessive lethal mutations of the lethal(2)giant discs (l(2)gd) and lethal(2)fat (l(2)ft) loci of Drosophila melanogaster cause imaginal disc hyperplasia during a prolonged larval stage. Imaginal discs from l(2)ft l(2)gd or Gl(2)gd double homozygotes show more extensive overgrowth than in either single homozygote, and double homozygous l(2)ft l(2)gd mitotic clones in adult flies show much more overgrowth than is seen in clones homozygous for either l(2)gd or l(2)ft alone. dachsous (ds) also acts as an enhancer of l(2)gd, producing dramatically overgrown discs and causing failure to pupariate in double homozygotes. The comb gap (cg) mutation, which also interacts with ds, greatly enhances the tendency of imaginal discs from l(2)gd larvae to duplicate as they overgrow. If l(2)gd homozygotes are made heterozygous for l(2)ft, then several discs duplicate, indicating that l(2)ft acts as a dominant enhancer of l(2)gd. l(2)ft also acts as a dominant enhancer of l(2)gd, and conversely l(2)gd acts as a dominant modifier of l(2)ft. The enhancement of overgrowth caused by various mutant combinations is accompanied by changes in expression of Decapentaplegic and Wingless. These results show that tumor suppressor genes act in combination to control cell proliferation, and that tissue hyperplasia can be associated with ectopic expression of genes involved in pattern formation. PMID:9335602
Fusion versus Bryan Cervical Disc in two-level cervical disc disease: a prospective, randomised study
Nie, Lin; Zhang, Li; Hou, Yong
In this prospective study, our aim was to compare the functional results and radiographic outcomes of fusion and Bryan Cervical Disc replacement in the treatment of two-level cervical disc disease. A total of 65 patients with two-level cervical disc disease were randomly assigned to two groups, those operated on with Bryan Cervical Disc replacement (31) and those operated on with anterior cervical fusion with an iliac crest autograft and plate (34). Clinical evaluation was carried out using the visual analogue scale (VAS), the Short Form 36 (SF-36) and the neck disability index (NDI) during a two year follow-up. Radiological evaluation sought evidence of range of motion, stability and subsidence of the prosthesis. Substantial reduction in NDI scores occurred in both groups, with greater percent improvement in the Bryan group (P = 0.023). The arm pain VAS score improvement was substantial in both groups. Bryan artificial cervical disc replacement seems reliable and safe in the treatment of patients with two-level cervical disc disease. PMID:18956190
Role of Cytokines in Intervertebral Disc Degeneration: Pain and Disc-content
Risbud, Makarand V.; Shapiro, Irving. M
Degeneration of the intervertebral disc is the major contributor to back/neck and radicular pain. It is characterized by an elevation in levels of the inflammatory cytokines tumor necrosis factor (TNF)-α, interleukin (IL)-1 α/β, IL-6 and IL-17 secreted by the disc cells themselves; these cytokines promote matrix degradation, chemokine production and changes in cell phenotype. The resulting imbalance between catabolic and anabolic responses leads to degeneration, as well as herniation and radicular pain. Release of chemokines from degenerating discs promote infiltration and activation of T and B cells, macrophages, neutrophils, and mast cells further amplifying the inflammatory cascade. Immunocyte migration into the disc is accompanied by the appearance of microvasculature and nerve fibers arising from the dorsal root ganglion (DRG). In this inflammatory milieu, neurogenic factors in particular nerve growth factor (NGF) and brain-derive neurotrophic factor (BDNF) generated by disc and immune cells induce expression of pain associated cation channels in DRGs. Depolarization of these channels is likely to promote discogenic and radicular pain and reinforce the cytokine-mediated degenerative cascade. Taken together, the enhanced understanding of the contribution of cytokines and immune cells to catabolic and nociceptive processes provide new targets for treating symptomatic disc disease. PMID:24166242
Tearing up a misaligned accretion disc with a binary companion
NASA Astrophysics Data System (ADS)
Doğan, Suzan; Nixon, Chris; King, Andrew; Price, Daniel J.
Accretion discs are common in binary systems, and they are often found to be misaligned with respect to the binary orbit. The gravitational torque from a companion induces nodal precession in misaligned disc orbits. We calculate whether this precession is strong enough to overcome the internal disc torques communicating angular momentum. For typical parameters precession wins: the disc breaks into distinct planes that precess effectively independently. We run hydrodynamical simulations to check these results, and confirm that disc breaking is widespread and generally enhances accretion on to the central object. This applies in many cases of astrophysical accretion, e.g. supermassive black hole binaries and X-ray binaries.
Counterrotating perfect fluid discs as sources of electrovacuum static spacetimes
NASA Astrophysics Data System (ADS)
García-Reyes, Gonzalo; González, Guillermo A.
The interpretation of some electrovacuum spacetimes in terms of counterrotating perfect fluid discs is presented. The interpretation is made by means of an 'inverse problem' approach used to obtain disc sources of known static solutions of the Einstein Maxwell equations. In order to do such an interpretation, a detailed study is presented of the counterrotating model (CRM) for generic electrovacuum static axially symmetric relativistic thin discs with nonzero radial pressure. Four simple families of models of counterrotating charged discs based on Chazy Curzon-type, Zipoy Voorhees-type, Bonnor Sackfield-type and charged and magnetized Darmois electrovacuum metrics are considered, where we obtain some discs with a well-behaved CRM.
Predicted influence of materials' thermal properties on disc brake roughness due to thermoelastic instability
Hecht, R.L.; Hartsock, D.L.; Dinwiddie, R.B.; Porter, W.D.
Passenger car disc brakes occasionally exhibit objectionable vibration during operation. Low frequency vibration (< 100 Hz) that occurs when the brakes are applied is called brake roughness or judder and is caused by a variation in torque at the friction interface. Brale torque variation can result from disc thickness variation and/or thermal distortions. Thermal distortions or hot spots may occur during a long brake drag such as a mountain descent due to the onset of a phenomenon known as frictionally excited thermoelastic instability (TEI). Models of TEI can be used to predict the propensity of a brake system to generate torque variation or roughness during long brake drags. TEI modeling requires accurate materials properties such as Young's modulus, Poisson's ratio, specific heat, thermal diffusivity, thermal conductivity, density and thermal expansion of both the disc and the brake pad materials. The authors have measured the thermal transport properties of a series of disc materials, gray cast irons and aluminum metal matrix composites, and commercially available brake pad friction materials. For example, room temperature thermal diffusivity measured by the laser flash technique was found to vary from 0.002--0.009 cm{sup 2}/sec for friction materials, 0.15--0.21 cm{sup 2}/sec for gray cast irons, and 0.43--0.89 cm{sup 2}/sec for aluminum metal matrix composites (Al MMCs). This paper will consider the behavior of Al MMC rotors versus traditional gray cast iron rotors coupled with a non-asbestos organic brake pad. The relevant materials properties were used in a TEI analytical model of a mid-sized passenger car disc brake. The analysis shows that Al MMC rotors have a lower critical speed at which TEI is predicted to occur than gray cast iron rotors.
Percutaneous endoscopic lumbar discectomy - early clinical experience.
Hirano, Yoshitaka; Mizuno, Junichi; Takeda, Masaaki; Itoh, Yasunobu; Matsuoka, Hidenori; Watanabe, Kazuo
We report our early clinical experience with percutaneous endoscopic lumbar discectomy (PELD) for herniated nucleus pulposus (HNP) in the lumbar spine. We introduced PELD to our clinical practice in June 2009. A total of 311 patients with degenerative lumbar spine disease were treated in our hospital up to August 2011. Thirty-seven patients with lumbar HNP were treated by PELD. PELD was carried out under local anesthesia, and the endoscope was continuously irrigated with saline. Twenty-eight patients were treated through the transforaminal approach, 5 were treated through the interlaminar approach, and 4 were treated through the extraforaminal approach. Surgery was discontinued due to uncontrollable intraoperative pain or anatomical inaccessibility in one case of the interlaminar approach and 2 cases of the extraforaminal approach. In the other 34 patients, the elapsed time of surgery was 34 to 103 minutes (mean 62.4 minutes). Extracorporeal blood loss was insignificant. Immediate symptom relief was achieved in all patients, and postoperative magnetic resonance imaging revealed sufficient removal of the HNP. The length of the postoperative hospital stay was 1 or 2 days in all patients. The surgical method of PELD is completely different from percutaneous nucleotomy, and the aim is to directly remove the HNP with minimum damage to the musculoskeletal structure. Although this study is based on our early clinical outcomes, PELD seemed to be a promising minimally invasive surgery for HNP in the lumbar spine. PMID:23006872
Percutaneous tracheostomy in patients on anticoagulants
Pasin, Laura; Frati, Elena; Cabrini, Luca; Giovanni, Landoni; Nardelli, Pasquale; Bove, Tiziana; Calabrò, Maria Grazia; Scandroglio, Anna Mara; Pappalardo, Federico; Zangrillo, Alberto
Aims: To determine if percutaneous tracheostomy is safe in critically ill patients treated with anticoagulant therapies. Settings and Design: Single-center retrospective study including all the patients who underwent percutaneous dilatational tracheostomy (PDT) placement over a 1-year period in a 14-bed, cardiothoracic and vascular Intensive Care Unit (ICU). Materials and Methods: Patients demographics and characteristics, anticoagulant and antiplatelet therapies, coagulation profile, performed technique and use of bronchoscopic guidance were retrieved. Results: Thirty-six patients (2.7% of the overall ICU population) underwent PDT over the study period. Twenty-six (72%) patients were on anticoagulation therapy, 1 patient was on antiplatelet therapy and 2 further patients received prophylactic doses of low molecular weight heparin. Only 4 patients had normal coagulation profile and were not receiving anticoagulant or antiplatelet therapies. Overall, bleeding of any severity complicated 19% of PDT. No procedure-related deaths occurred. Conclusions: PDT was proved to be safe even in critically ill-patients treated with anticoagulant therapies. Larger prospective studies are needed to confirm our findings. PMID:26139737
Laparoscopic-Assisted Percutaneous Endoscopic Gastrostomy.
Thaker, Adarsh M; Sedarat, Alireza
There are a variety of techniques for gastrostomy tube placement. Endoscopic and radiologic approaches have almost entirely superseded surgical placement. However, an aging population and significant advancements in modern healthcare have resulted in patients with increasingly complex medical issues or postsurgical anatomy. The rising prevalence of obesity has also created technical challenges for proceduralists of many specialties. When patients with these comorbidities develop the need for long-term enteral nutrition and feeding tube placement, standard approaches such as percutaneous endoscopic gastrostomy (PEG) by endoscopists and percutaneous image-guided gastrostomy (PIG) by interventional radiologists may be technically difficult or impossible. For these challenging situations, laparoscopic-assisted PEG (LAPEG) is an alternative option. LAPEG combines the advantages of PEG with direct intraperitoneal visualization, helping ensure a safe tube placement tract free of intervening organs or structures. In this review, we highlight some of the important factors of first-line gastrostomy techniques, with an emphasis on the utility and procedural technique of LAPEG when they are not feasible. PMID:27422123
[Percutaneous tracheostomy in the ventilated patient].
Añón, J M; Araujo, J B; Escuela, M P; González-Higueras, E
The medical indications of tracheostomy comprise the alleviation of upper airway obstruction; the prevention of laryngeal and upper airway damage due to prolonged translaryngeal intubation in patients subjected to prolonged mechanical ventilation; and the facilitation of airway access for the removal of secretions. Since 1985, percutaneous tracheostomy (PT) has gained widespread acceptance as a method for creating a surgical airway in patients requiring long-term mechanical ventilation. Since then, several comparative trials of PT and surgical tracheostomy have been conducted, and new techniques for PT have been developed. The use of percutaneous dilatation techniques under bronchoscopic control are now increasingly popular throughout the world. Tracheostomy should be performed as soon as the need for prolonged intubation is identified. However a validated model for the prediction of prolonged mechanical ventilation is not available, and the timing of tracheostomy should be individualized. The present review analyzes the state of the art of PT in mechanically ventilated patients--this being regarded by many as the technique of choice in performing tracheostomy in critically ill patients. PMID:23347906
Turbulence-induced disc formation in strongly magnetized cloud cores
NASA Astrophysics Data System (ADS)
Seifried, D.; Banerjee, R.; Pudritz, R. E.; Klessen, R. S.
We present collapse simulations of strongly magnetized, turbulent molecular cloud cores with masses ranging from 2.6 to 1000 M⊙ in order to study the influence of the initial conditions on the turbulence-induced disc formation mechanism proposed recently by Seifried et al. We find that Keplerian discs are formed in all cases independently of the core mass, the strength of turbulence or the presence of global rotation. The discs appear within a few kyr after the formation of the protostar, are 50-150 au in size, and have masses between 0.05 and a few 0.1 M⊙. During the formation of the discs the mass-to-flux ratio stays well below the critical value of 10 for Keplerian disc formation. Hence, flux-loss alone cannot explain the formation of Keplerian discs. The formation of rotationally supported discs at such early phases is rather due to the disordered magnetic field structure and due to turbulent motions in the surroundings of the discs, two effects lowering the classical magnetic braking efficiency. Binary systems occurring in the discs are mainly formed via the disc capturing mechanism rather than via disc fragmentation, which is largely suppressed by the presence of magnetic fields.
Dynamics of a disc in a nematic liquid crystal.
Antipova, Alena; Denniston, Colin
We use lattice Boltzmann simulations to study the dynamics of a disc immersed in a nematic liquid crystal. In the absence of external torques, discs with homeotropic anchoring align with their surface normal parallel to the director of the nematic liquid crystal. In the presence of a weak magnetic field a ferromagnetic disc will rotate to equilibrate the elastic torque due to the distortion of the nematic director and the magnetic torque. When the magnetic field rotates the disc so that the angle θ between normal to the surface of the disc â and director of the liquid crystal n[combining circumflex] becomes greater than π/2, the disc flips around the axis perpendicular to the rotation axis so that â sweeps through π radians. An analysis of this behaviour was performed. In particular, we look at the impact of the disc thickness and edges on defect creation and the flipping transition. We also analyse the importance of backflow. PMID:26575160
Examination of turbine discs from nuclear power plants
Czajkowski, C.J.; Weeks, J.R.
Investigations were performed on a cracked turbine disc from the Cooper Nuclear Power Station, and on two failed turbine discs (governor and generator ends) from the Yankee-Rowe Nuclear Power Station. Cooper is a boiling water reactor (BWR) which went into commercial operation in July 1974, and Yankee-Rowe is a pressurized water reactor (PWR) which went into commercial operation in June 1961. Cracks were identified in the bore of the Cooper disc after 41,913 hours of operation, and the disc removed for repair. At Yankee-Rowe two discs failed after 100,000 hours of operation. Samples of the Cooper disc and both Yankee-Rowe disc (one from the governor and one from the generator end of the LP turbine) were sent to Brookhaven National Laboratory (BNL) for failure analysis.
Percutaneous Relief of Tension Pneumomediastinum in a Child
Chau, Helen Hoi-lun; Kwok, Philip Chong-hei; Lai, Albert Kwok-hung; Fan, Tsz Wo; Chan, Susan Chi-hum; Miu, Ting Yat; Chan, Grace Lai-har
The purpose of this article was to describe the experience of relieving tension pneumomediastinum by a fluoroscopic-guided percutaneous method. We inserted a percutaneous drainage catheter with a Heimlich valve under fluoroscopic guidance to relieve the tension pneumomediastinum in a 2-year-old girl who suffered from dermatomyositis with lung involvement. This allowed immediate relief without the need for surgery. The procedure was repeated for relapsed tension pneumomediastinum. Good immediate results were achieved in each attempt. We conclude that percutaneous relief of pneumomediastinum under fluoroscopic guidance can be performed safely and rapidly in patients not fit for surgery.
Percutaneous embolization of varicocele: technique, indications, relative contraindications, and complications
Halpern, Joshua; Mittal, Sameer; Pereira, Keith; Bhatia, Shivank; Ramasamy, Ranjith
There are several options for the treatment of varicocele, including surgical repair either by open or microsurgical approach, laparoscopy, or through percutaneous embolization of the internal spermatic vein. The ultimate goal of varicocele treatment relies on the occlusion of the dilated veins that drain the testis. Percutaneous embolization offers a rapid recovery and can be successfully accomplished in approximately 90% of attempts. However, the technique demands interventional radiologic expertise and has potential serious complications, including vascular perforation, coil migration, and thrombosis of pampiniform plexus. This review discusses the common indications, relative contraindications, technical details, and risks associated with percutaneous embolization of varicocele. PMID:26658060
Percutaneous Procedures for the Treatment of Trigeminal Neuralgia.
Bender, Matthew T; Bettegowda, Chetan
Three major percutaneous procedures are currently used to treat trigeminal neuralgia (TN). Percutaneous balloon compression, glycerol rhizotomy, and radiofrequency thermocoagulation interrupt afferent pain fibers by injury to the trigeminal nerve root or ganglion. Each is capable of offering immediate and durable pain relief. Each is associated with relatively low, but variable rates of complications. Patient heterogeneity, technical variation, and nonstandard outcomes plague the existing outcomes literature and limit comparisons of treatments. Rendering treatment selection a function of individual physician preference and practice patterns. Randomized, prospective trials are needed; in the meantime, percutaneous rhizotomy remains an excellent treatment for selected patients. PMID:27324995
The inferior vena cava clip. The percutaneous approach.
Bildsoe, M C; Yedlicka, J W; Hunter, D W; Castañeda-Zúñiga, W R; Amplatz, K
Pulmonary embolism in high-risk patients may be minimized by surgical inferior vena cava (IVC) clipping or by the insertion of caval filters. A percutaneous clipping technique was developed that narrows the cava while allowing caval patency. The caval clip is inserted through a percutaneous translumbar approach under fluoroscopic control. Nine dogs underwent percutaneous translumbar caval clip placement without complications. Three of four dogs, followed-up for 5 to 19 weeks by angiography and caval pressure measurements, showed caval patency. This technique eliminates the risks of surgical IVC clip placement and risks from the insertion of intravascular foreign bodies such as filters. PMID:2394568
Percutaneous embolization of varicocele: technique, indications, relative contraindications, and complications.
Halpern, Joshua; Mittal, Sameer; Pereira, Keith; Bhatia, Shivank; Ramasamy, Ranjith
There are several options for the treatment of varicocele, including surgical repair either by open or microsurgical approach, laparoscopy, or through percutaneous embolization of the internal spermatic vein. The ultimate goal of varicocele treatment relies on the occlusion of the dilated veins that drain the testis. Percutaneous embolization offers a rapid recovery and can be successfully accomplished in approximately 90% of attempts. However, the technique demands interventional radiologic expertise and has potential serious complications, including vascular perforation, coil migration, and thrombosis of pampiniform plexus. This review discusses the common indications, relative contraindications, technical details, and risks associated with percutaneous embolization of varicocele. PMID:26658060
Percutaneous transhepatic thrombectomy and pharmacologic thrombolysis of mesenteric venous thrombosis.
Zhou, Wei; Choi, Lorraine; Lin, Peter H; Dardik, Alan; Eraso, Andrea; Lumsden, Alan B
Mesenteric venous occlusion is a rare yet highly morbid condition that is traditionally treated with anticoagulation while surgery serves as the last resort. Percutaneous intervention provides an effective option with relatively low mortality and morbidity. We herein describe use of transhepatic percutaneous thrombectomy and pharmacologic thrombolysis in treating two cases of symptomatic mesenteric venous thrombosis. These cases underscore the fact that transhepatic thrombectomy and thrombolysis are a highly effective strategy for treating acute symptomatic mesenteric venous thrombosis. Several percutaneous techniques are also reviewed. PMID:17382054
Structure formation in gas-rich galactic discs with finite thickness: from discs to rings
NASA Astrophysics Data System (ADS)
Behrendt, M.; Burkert, A.; Schartmann, M.
Gravitational instabilities play an important role in structure formation of gas-rich high-redshift disc galaxies. In this paper, we revisit the axisymmetric perturbation theory and the resulting growth of structure by taking the realistic thickness of the disc into account. In the unstable regime, which corresponds for thick discs to a Toomre parameter below the critical value Q0, crit = 0.696, we find a fastest growing perturbation wavelength that is always a factor 1.93 times larger than in the classical razor-thin disc approximation. This result is independent of the adopted disc scaleheight and by this independent of temperature and surface density. In order to test the analytical theory, we compare it with a high-resolution hydrodynamical simulation of an isothermal gravitationally unstable gas disc with the typical vertical sech2 density profile and study its break up into rings that subsequently fragment into dense clumps. In the first phase, rings form, that organize themselves discretely, with distances corresponding to the local fastest growing perturbation wavelength. We find that the disc scaleheight has to be resolved initially with five or more grid cells in order to guarantee proper growth of the ring structures, which follow the analytical prediction. These rings later on contract to a thin and dense line, while at the same time accreting more gas from the inter-ring region. It is these dense, circular filaments, that subsequently fragment into a large number of clumps. Contrary to what is typically assumed, the clump sizes are therefore not directly determined by the fastest growing wavelength.
Percutaneous Transpedicular Interbody Fusion Technique in Percutaneous Pedicle Screw Stabilization for Pseudoarthrosis Following Pyogenic Spondylitis
Masuda, Keigo; Yonekura, Yutaka; Kitamura, Takahiro; Senba, Hideyuki; Shidahara, Satoshi
This report introduces a percutaneous transpedicular interbody fusion (PTPIF) technique in posterior stabilization using percutaneous pedicle screws (PPSs). An 81-year-old man presented with pseudoarthrosis following pyogenic spondylitis 15 months before. Although no relapse of infection was found, he complained of obstinate low back pain and mild neurological symptoms. Radiological evaluations showed a pseudoarthrosis following pyogenic spondylitis at T11–12. Posterior stabilization using PPSs from Th9 to L2 and concomitant PTPIF using autologous iliac bone graft at T11–12 were performed. Low back pain and neurological symptoms were immediately improved after surgery. A solid interbody fusion at T11–12 was completed 9 months after surgery. The patient had no restriction of daily activity and could play golf at one year after surgery. PTPIF might be a useful option for perform segmental fusion in posterior stabilization using PPSs. PMID:27114777
Percutaneous Transpedicular Interbody Fusion Technique in Percutaneous Pedicle Screw Stabilization for Pseudoarthrosis Following Pyogenic Spondylitis.
Ikuta, Ko; Masuda, Keigo; Yonekura, Yutaka; Kitamura, Takahiro; Senba, Hideyuki; Shidahara, Satoshi
This report introduces a percutaneous transpedicular interbody fusion (PTPIF) technique in posterior stabilization using percutaneous pedicle screws (PPSs). An 81-year-old man presented with pseudoarthrosis following pyogenic spondylitis 15 months before. Although no relapse of infection was found, he complained of obstinate low back pain and mild neurological symptoms. Radiological evaluations showed a pseudoarthrosis following pyogenic spondylitis at T11-12. Posterior stabilization using PPSs from Th9 to L2 and concomitant PTPIF using autologous iliac bone graft at T11-12 were performed. Low back pain and neurological symptoms were immediately improved after surgery. A solid interbody fusion at T11-12 was completed 9 months after surgery. The patient had no restriction of daily activity and could play golf at one year after surgery. PTPIF might be a useful option for perform segmental fusion in posterior stabilization using PPSs. PMID:27114777
Cervical disc arthroplasty: Pros and cons
Moatz, Bradley; Tortolani, P. Justin
Background: Cervical disc arthroplasty has emerged as a promising potential alternative to anterior cervical discectomy and fusion (ACDF) in appropriately selected patients. Despite a history of excellent outcomes after ACDF, the question as to whether a fusion leads to adjacent segment degeneration remains unanswered. Numerous US investigational device exemption trials comparing cervical arthroplasty to fusion have been conducted to answer this question. Methods: This study reviews the current research regarding cervical athroplasty, and emphasizes both the pros and cons of arthroplasty as compared with ACDF. Results: Early clinical outcomes show that cervical arthroplasty is as effective as the standard ACDF. However, this new technology is also associated with an expanding list of novel complications. Conclusion: Although there is no definitive evidence that cervical disc replacement reduces the incidence of adjacent segment degeneration, it does show other advantages; for example, faster return to work, and reduced need for postoperative bracing. PMID:22905327
Inflammation in intervertebral disc degeneration and regeneration
Molinos, Maria; Almeida, Catarina R.; Caldeira, Joana; Cunha, Carla; Gonçalves, Raquel M.; Barbosa, Mário A.
Intervertebral disc (IVD) degeneration is one of the major causes of low back pain, a problem with a heavy economic burden, which has been increasing in prevalence as populations age. Deeper knowledge of the complex spatial and temporal orchestration of cellular interactions and extracellular matrix remodelling is critical to improve current IVD therapies, which have so far proved unsatisfactory. Inflammation has been correlated with degenerative disc disease but its role in discogenic pain and hernia regression remains controversial. The inflammatory response may be involved in the onset of disease, but it is also crucial in maintaining tissue homeostasis. Furthermore, if properly balanced it may contribute to tissue repair/regeneration as has already been demonstrated in other tissues. In this review, we focus on how inflammation has been associated with IVD degeneration by describing observational and in vitro studies as well as in vivo animal models. Finally, we provide an overview of IVD regenerative therapies that target key inflammatory players. PMID:25673296
New Experiments with Spinning Metallic Discs
NASA Technical Reports Server (NTRS)
Mazuruk, Konstantin; Grugel, Richard N.
A number of recent advanced theories related to torsion properties of the space-time matrix predict the existence of an interaction between classically spinning objects. Indeed, some experimental data suggest that spinning magnetic bodies discernibly interact with Earth's natural fields. If there are interactions between rotating bodies then nuclear spins could be used for detection. Thus, assuming a spinning body induces a hypothetical torsion field, a sensor based on the giant magnetoresistance effect would detect local changes. Experimentally, spinning a brass wheel shielded from Earth's magnetic field showed no measurable change in signals; with no shielding a Faraday disc phenomenon was observed. Unexpected experimental measurements from the non-axial Faraday disc configuration were recorded and a theoretical model was derived to explain them.
Material Science in Cervical Total Disc Replacement
Pham, Martin H.; Mehta, Vivek A.; Tuchman, Alexander; Hsieh, Patrick C.
Current cervical total disc replacement (TDR) designs incorporate a variety of different biomaterials including polyethylene, stainless steel, titanium (Ti), and cobalt-chrome (CoCr). These materials are most important in their utilization as bearing surfaces which allow for articular motion at the disc space. Long-term biological effects of implanted materials include wear debris, host inflammatory immune reactions, and osteolysis resulting in implant failure. We review here the most common materials used in cervical TDR prosthetic devices, examine their bearing surfaces, describe the construction of the seven current cervical TDR devices that are approved for use in the United States, and discuss known adverse biological effects associated with long-term implantation of these materials. It is important to appreciate and understand the variety of biomaterials available in the design and construction of these prosthetics and the considerations which guide their implementation. PMID:26523281
Material Science in Cervical Total Disc Replacement.
Pham, Martin H; Mehta, Vivek A; Tuchman, Alexander; Hsieh, Patrick C
Current cervical total disc replacement (TDR) designs incorporate a variety of different biomaterials including polyethylene, stainless steel, titanium (Ti), and cobalt-chrome (CoCr). These materials are most important in their utilization as bearing surfaces which allow for articular motion at the disc space. Long-term biological effects of implanted materials include wear debris, host inflammatory immune reactions, and osteolysis resulting in implant failure. We review here the most common materials used in cervical TDR prosthetic devices, examine their bearing surfaces, describe the construction of the seven current cervical TDR devices that are approved for use in the United States, and discuss known adverse biological effects associated with long-term implantation of these materials. It is important to appreciate and understand the variety of biomaterials available in the design and construction of these prosthetics and the considerations which guide their implementation. PMID:26523281
[Diagnostics and therapy of spinal disc herniation].
Zimmer, A; Reith, W
Degenerative processes in a movement segment of the vertebral column, which can potentially give rise to herniation of elements of the nucleus pulposus, are complex and of variable clinical and radiological dimensions; however the mere assumption that degenerative changes precede disc herniation remains a matter of debate. By definition, spinal disc herniation (SDH) refers to components of the gelatinous nucleus pulposus protruding beyond the dorsal level of the vertebral body margin through tears in the annulus fibrosus. Clinical presentation may include pain, paresis and sensory disturbances. Magnetic resonance imaging (MRI) is considered the gold standard in the diagnosis of SDH. In the majority of patients a conservative approach with physical therapy exercises and adequate analgesic and antiphlogistic medical treatment results in a substantial improvement of symptoms. PMID:25398570
Thalamic Pain Misdiagnosed as Cervical Disc Herniation
Lim, Tae Ha; Choi, Soo Il; Yoo, Jee In; Choi, Young Soon; Lim, Young Su; Sang, Bo Hyun; Bang, Yun Sic
Thalamic pain is a primary cause of central post-stroke pain (CPSP). Clinical symptoms vary depending on the location of the infarction and frequently accompany several pain symptoms. Therefore, correct diagnosis and proper examination are not easy. We report a case of CPSP due to a left acute thalamic infarction with central disc protrusion at C5-6. A 45-year-old-male patient experiencing a tingling sensation in his right arm was referred to our pain clinic under the diagnosis of cervical disc herniation. This patient also complained of right cramp-like abdominal pain. After further evaluations, he was diagnosed with an acute thalamic infarction. Therefore detailed history taking should be performed and examiners should always be aware of other symptoms that could suggest a more dangerous disease. PMID:27103967
Planetesimal formation in self-gravitating discs
NASA Astrophysics Data System (ADS)
Gibbons, P. G.; Rice, W. K. M.; Mamatsashvili, G. R.
We study particle dynamics in local two-dimensional simulations of self-gravitating accretion discs with a simple cooling law. It is well known that the structure which arises in the gaseous component of the disc due to a gravitational instability can have a significant effect on the evolution of dust particles. Previous results using global simulations indicate that spiral density waves are highly efficient at collecting dust particles, creating significant local overdensities which may be able to undergo gravitational collapse. We expand on these findings using a range of cooling times to mimic the conditions at a large range of radii within the disc. Here we use the PENCIL code to solve the 2D local shearing sheet equations for gas on a fixed grid together with the equations of motion for solids coupled to the gas solely through aerodynamic drag force. We find that spiral density waves can create significant enhancements in the surface density of solids, equivalent to 1-10 cm sized particles in a disc following the profiles of Clarke around an ˜1 M⊙ star, causing it to reach concentrations several orders of magnitude larger than the particles mean surface density. We also study the velocity dispersion of the particles, finding that the spiral structure can result in the particle velocities becoming highly ordered, having a narrow velocity dispersion. This implies low relative velocities between particles, which in turn suggest that collisions are typically low energy, lessening the likelihood of grain destruction. Both these findings suggest that the density waves that arise due to gravitational instabilities in the early stages of star formation provide excellent sites for the formation of large, planetesimal-sized objects.
The Astral Curved Disc of Chevroches (France)
NASA Astrophysics Data System (ADS)
Devevey, F. Rousseau, A.
The excavation of the unexplored secondary agglomeration in Chevroches (Nièvre), from 2001 to 2002, directed by F. Devevey (INRAP), has led to the discovery of an astrological bronze curved disc of a type unknown in the ancient world; it is inscribed with three lines in Greek transcribing Egyptian an Roman months, and the twelve signs of the zodiac. This article presents the first observations.
Inner disc obscuration in GRS 1915+105 based on relativistic slim disc model
NASA Astrophysics Data System (ADS)
Vierdayanti, K.; Sadowski, A.; Mineshige, S.; Bursa, M.
We study the observational signatures of the relativistic slim disc of 10 M⊙ black hole, in a wide range of mass accretion rate, dot{m}, dimensionless spin parameter, a*, and viewing angle, i. In general, the innermost temperature, Tin, increases with the increase of i for a fixed value of dot{m} and a*, due to the Doppler effect. However, for i > 50° and dot{m}>dot{m}_turn, Tin starts to decrease with the increase of dot{m}. This is a result of self-obscuration - the radiation from the innermost hot part of the disc is blocked by the surrounding cooler part. The value of dot{m}_turn and the corresponding luminosities depend on a* and i. Such obscuration effects cause an interesting behaviour on the disc luminosity (Ldisc)-Tin plane for high inclinations. In addition to the standard disc branch which appears below dot{m}_turn and which obeys L_disc ∝ T_in4 relation, another branch above dot{m}_turn, which is nearly horizontal, may be observed at luminosities close to the Eddington luminosity. We show that these features are likely observed in a Galactic X-ray source, GRS 1915+105. We support a high spin parameter (a* > 0.9) for GRS 1915+105 since otherwise the high value of Tin and small size of the emitting region (rin < 1rS) cannot be explained.
Reactive thin film flows over spinning discs
NASA Astrophysics Data System (ADS)
Zhao, Kun; Wray, Alex; Yang, Junfeng; Matar, Omar
We consider the dynamics of a thin film flowing over a spinning disc in the presence of a chemical reaction, and associated heat and mass transfer. We use a boundary-layer approximation in conjunction with the Karman-Polhausen approximation for the velocity distribution in the film to derive a set of coupled one-dimensional evolution equations for the film thickness, radial and azimuthal flow rates, concentration of the reagents and products, and temperature. These highly nonlinear partial differential equations are solved numerically to reveal the formation of large-amplitude waves that travel from the disc inlet to its periphery. The influence of these waves on the concentration and temperature profiles is analysed for a wide range of system parameters: the Damkohler and Schmidt numbers, the thermal Peclet numbers, and the dimensionless disc radius (a surrogate for the Eckman number). It is shown that these waves lead to significant enhancement of the rates of heat and mass transfer associated with the reactive flow; these are measured by tracking the temporal evolution of local and spatially-averaged Nusselt and Sherwood numbers, respectively. EPSRC Programme Grant, MEMPHIS, EP/K0039761/1.
Risk Factors for Recurrent Lumbar Disc Herniation
Huang, Weimin; Han, Zhiwei; Liu, Jiang; Yu, Lili; Yu, Xiuchun
Abstract Recurrent lumbar disc herniation (rLDH) is a common complication following primary discectomy. This systematic review aimed to investigate the current evidence on risk factors for rLDH. Cohort or case-control studies addressing risk factors for rLDH were identified by search in Pubmed (Medline), Embase, Web of Science, and Cochrane library from inception to June 2015. Relevant results were pooled to give overall estimates if possible. Heterogeneity among studies was examined and publication bias was also assessed. A total of 17 studies were included in this systematic review. Risk factors that had significant relation with rLDH were smoking (OR 1.99, 95% CI 1.53–2.58), disc protrusion (OR 1.79, 95% CI 1.15–2.79), and diabetes (OR 1.19, 95% CI 1.06–1.32). Gender, BMI, occupational work, level, and side of herniation did not correlate with rLDH significantly. Based on current evidence, smoking, disc protrusion, and diabetes were predictors for rLDH. Patients with these risk factors should be paid more attention for prevention of recurrence after primary surgery. More evidence provided by high-quality observational studies is still needed to further investigate risk factors for rLDH. PMID:26765413
Testing hydrodynamics schemes in galaxy disc simulations
NASA Astrophysics Data System (ADS)
Few, C. G.; Dobbs, C.; Pettitt, A.; Konstandin, L.
We examine how three fundamentally different numerical hydrodynamics codes follow the evolution of an isothermal galactic disc with an external spiral potential. We compare an adaptive mesh refinement code (RAMSES), a smoothed particle hydrodynamics code (SPHNG), and a volume-discretized mesh-less code (GIZMO). Using standard refinement criteria, we find that RAMSES produces a disc that is less vertically concentrated and does not reach such high densities as the SPHNG or GIZMO runs. The gas surface density in the spiral arms increases at a lower rate for the RAMSES simulations compared to the other codes. There is also a greater degree of substructure in the SPHNG and GIZMO runs and secondary spiral arms are more pronounced. By resolving the Jeans length with a greater number of grid cells, we achieve more similar results to the Lagrangian codes used in this study. Other alterations to the refinement scheme (adding extra levels of refinement and refining based on local density gradients) are less successful in reducing the disparity between RAMSES and SPHNG/GIZMO. Although more similar, SPHNG displays different density distributions and vertical mass profiles to all modes of GIZMO (including the smoothed particle hydrodynamics version). This suggests differences also arise which are not intrinsic to the particular method but rather due to its implementation. The discrepancies between codes (in particular, the densities reached in the spiral arms) could potentially result in differences in the locations and time-scales for gravitational collapse, and therefore impact star formation activity in more complex galaxy disc simulations.
Transmyocardial Laser Revascularization.
Horvath, Keith A.
Transmyocardial laser revascularization (TMR) has been performed on over 12,000 patients worldwide. Since 1990, the treatment has provided significant angina relief for symptomatic end-stage coronary disease that is refractory to medical therapy. Seventy-five percent of patients treated with TMR have demonstrated a decrease of two or more angina classes postoperatively. As a result, TMR has provided a significant improvement in quality of life for patients, resulting in fewer hospital admissions and decreased dependency on medications. Two different wavelengths of light, carbon dioxide (CO(2)) and holmium yttrium-aluminum-garnet (Ho:YAG), have been employed. Results obtained using these lasers differ. The CO(2) laser has demonstrated a perfusion benefit as well as long-term improvement in quality of life and angina relief. The Ho:YAG laser has not demonstrated these results. These differences may, in part, explain the failure of percutaneous myocardial laser revascularization. This catheter-based approach was not as successful as TMR due to its partial thickness treatment of the myocardium as well as its use of the Ho:YAG laser. In addition to the patients with end-stage coronary disease who undergo TMR as sole therapy, there are an increasing number of patients who have been treated with a combination of coronary artery bypass grafting and TMR. This provides a more complete revascularization than leaving territories ungrafted. Further enhancement of the angiogenic response seen after TMR may be seen by the addition of gene therapy to TMR treatment. PMID:15023284
Age-related percutaneous penetration part 1: skin factors.
Konda, S; Meier-Davis, S R; Cayme, B; Shudo, J; Maibach, H I
Changes in the skin that occur in the elderly may put them at increased risk for altered percutaneous penetration from pharmacotherapy along with potential adverse effects. Skin factors that may have a role in age-related percutaneous penetration include blood flow, pH, skin thickness, hair and pore density, and the content and structure of proteins, glycosaminoglycans (GAGs), water, and lipids. Each factor is examined as a function of increasing age along with its potential impact on percutaneous penetration. Additionally, topical drugs that successfully overcome the barrier function of the skin can still fall victim to cutaneous metabolism, thereby producing metabolites that may have increased or decreased activity. This overview discusses the current data and highlights the importance of further studies to evaluate the impact of skin factors in age-related percutaneous penetration. PMID:22622279
Be discs in binary systems - I. Coplanar orbits
NASA Astrophysics Data System (ADS)
Panoglou, Despina; Carciofi, Alex C.; Vieira, Rodrigo G.; Cyr, Isabelle H.; Jones, Carol E.; Okazaki, Atsuo T.; Rivinius, Thomas
Be stars are surrounded by outflowing circumstellar matter structured in the form of decretion discs. They are often members of binary systems, where it is expected that the decretion disc interacts both radiatively and gravitationally with the companion. In this work we study how various orbital (period, mass ratio and eccentricity) and disc (viscosity) parameters affect the disc structure in coplanar binaries. The main effects of the secondary on the disc are its truncation and the accumulation of material inwards of truncation. We find two limiting cases with respect to the effects of eccentricity: in circular or nearly circular prograde orbits, the disc maintains a rotating, constant in shape, configuration, which is locked to the orbital phase. The disc structure appears smaller in size, more elongated and more massive for small viscosity parameter, small orbital separation and/or high mass ratio. In highly eccentric orbits, the effects are more complex, with the disc structure strongly dependent on the orbital phase. We also studied the effects of binarity in the disc continuum emission. Since the infrared and radio SED are sensitive to the disc size and density slope, the truncation and matter accumulation result in considerable modifications in the emergent spectrum. We conclude that binarity can serve as an explanation for the variability exhibited in observations of Be stars, and that our model can be used to detect invisible companions.
Density waves in debris discs and galactic nuclei
NASA Astrophysics Data System (ADS)
Jalali, Mir Abbas; Tremaine, Scott
We study the linear perturbations of collisionless near-Keplerian discs. Such systems are models for debris discs around stars and the stellar discs surrounding supermassive black holes at the centres of galaxies. Using a finite-element method, we solve the linearized collisionless Boltzmann equation and Poisson's equation for a wide range of disc masses and rms orbital eccentricities to obtain the eigenfrequencies and shapes of normal modes. We find that these discs can support large-scale 'slow' modes, in which the frequency is proportional to the disc mass. Slow modes are present for arbitrarily small disc mass so long as the self-gravity of the disc is the dominant source of apsidal precession. We find that slow modes are of two general types: parent modes and hybrid child modes, the latter arising from resonant interactions between parent modes and singular van Kampen modes. The most prominent slow modes have azimuthal wavenumbers m= 1 and m= 2. We illustrate how slow modes in debris discs are excited during a fly-by of a neighbouring star. Many of the non-axisymmetric features seen in debris discs (clumps, eccentricity, spiral waves) that are commonly attributed to planets could instead arise from slow modes; the two hypotheses can be distinguished by long-term measurements of the pattern speed of the features.
Construction Strategy and Progress of Whole Intervertebral Disc Tissue Engineering.
Yang, Qiang; Xu, Hai-Wei; Hurday, Sookesh; Xu, Bao-Shan
Degenerative disc disease (DDD) is the major cause of low back pain, which usually leads to work absenteeism, medical visits and hospitalization. Because the current conservative procedures and surgical approaches to treatment of DDD only aim to relieve the symptoms of disease but not to regenerate the diseased disc, their long-term efficiency is limited. With the rapid developments in medical science, tissue engineering techniques have progressed markedly in recent years, providing a novel regenerative strategy for managing intervertebral disc disease. However, there are as yet no ideal methods for constructing tissue-engineered intervertebral discs. This paper reviews published reports pertaining to intervertebral disc tissue engineering and summarizes data concerning the seed cells and scaffold materials for tissue-engineered intervertebral discs, construction of tissue-engineered whole intervertebral discs, relevant animal experiments and effects of mechanics on the construction of tissue-engineered intervertebral disc and outlines the existing problems and future directions. Although the perfect regenerative strategy for treating DDD has not yet been developed, great progress has been achieved in the construction of tissue-engineered intervertebral discs. It is believed that ongoing research on intervertebral disc tissue engineering will result in revolutionary progress in the treatment of DDD. PMID:27028376
Embolic protection devices in saphenous percutaneous intervention.
Morís, Cesar; Lozano, Iñigo; Martín, María; Rondán, Juán; Avanzas, Pablo
Saphenous veins remain a source of conduit for use in surgical coronary bypass graft revascularisation procedures. Saphenous vein grafts have a progressive closure rate estimated to be 12% to 20% at the end of the first year, and approximately 50% by 10 years. Regarding secondary revascularisation in these cases, reoperation carries substantially increased morbidity and mortality rates, making saphenous coronary intervention, in particular stent implantation, a more attractive means of revascularisation. However, this procedure carries a significant risk of major adverse clinical events, predominantly myocardial infarction or reduced antegrade flow (non-reflow phenomenon), mainly due to distal embolisation of atherothrombotic debris and distal microvascular occlusion. Embolic protection devices are used to reduce the risk of distal embolisation. There are two different designs: filter and occlusion-aspiration devices. In this article we present the different systems of embolic protection devices in saphenous percutaneous intervention and the previously published information is reviewed. PMID:19736070
Magnetic electrical connectors for biomedical percutaneous implants
NASA Technical Reports Server (NTRS)
Owens, L. J. (Inventor)
A biomedical percutaneous connector is described which includes a socket having an enlarged disk shaped base portion for being implanted below the patient's skin and cylindrical portion which is integral with the base portion and extends outwardly of the skin. A conical recess in an upper end of the cylindrical portion has a magnet located in the base. Inclined conductive strips are carried on an upper end of the cylindrical portion to which electrical conductors are attached and extend into the patient's body. A complementary shaped plug which also has electrical contacts provided thereon is adapted to fit within the conical recess of the socket. The plug is held in the socket by magnetic force.
Percutaneous absorption and disposition of Tinopal EMS.
Black, J G; Moule, R C; Philp, J
A cotton-substantive, anionic, fluorescent whitening agent manufactured by several suppliers under various trade names e.g. Tinopal EMS, has been synthesized in radioactive form. Intubation of detergent or aqueous solution into rats resulted in little absorption from the intestinal tract as evidenced by low radioactivity in the urine and tissues. Most of the dose was excreted rapidly in the faeces. After parenteral administration to rats, the radioactivity was rapidly excreted in the faeces with small amounts remaining in tissues and organs. There was slight evidence of retention of radioactivity in the kidneys. Very small amounts of Tinopal EMS in detergent were absorbed through rat skin, but only when concentrations greater than those normally used by the consumer, together with occlusion of the skin were employed. Small amounts were absorbed throught skin when applied in ethanol. It is concluded that the possibility of systemic toxic effects in man as a result of percutaneous absorption is remote. PMID:929616
Percutaneous Retrieval of a Right Atrioventricular Embolus
Davies, Roger Philip; Harding, James; Hassam, Rhonda
Percutaneous retrieval of a 12-cm-long serpiginous clot lodged in the right atrium and ventricle is reported. Following bilateral common femoral vein puncture, a Bird's Nest cava filter was first positioned ready to deploy immediately below the renal veins via the right femoral vein. From the left femoral vein, a Cook intravascular retrieval basket was advanced to the right atrium. Under transthoracic echocardiographic visualization, the basket was used to engage, trap, and gently withdraw the clot in a single long strand below the prepositioned inferior vena cava filter. The filter was immediately deployed, leaving the clot trapped inferior to the renal veins, in the cava and left iliac vein. The patient remained well and asymptomatic at discharge.
Percutaneous Placement and Management of Peritoneovenous Shunts
Martin, Louis G.
Peritoneovenous shunts are used in the treatment of recurrent ascites or recurrent pleural effusions. Generally speaking, the shunts allow passage of ascites or pleural effusions (by either passive or active means) back into the central venous system. The most recent development in peritoneovenous shunts, known as the Denver Shunt, is a modification of a shunt developed for the treatment of hydrocephalus. In recent years, the Denver shunt has been placed by interventional radiologists. It is used to treat both cirrhotic and malignant effusions in the peritoneal and pleural cavities. Reported complications of the shunt are shunt occlusion, infection, post-shunt coagulopathy, deep vein thrombosis, catheter breakage, and leaks. This article discusses the technical aspects related to the percutaneous placement and maintenance of the Denver Shunt. PMID:23729983
Bioresorbable scaffolds for percutaneous coronary interventions
Gogas, Bill D.
Innovations in drug-eluting stents (DES) have substantially reduced rates of in-segment restenosis and early stent thrombosis, improving clinical outcomes following percutaneous coronary interventions (PCI). However a fixed metallic implant in a vessel wall with restored patency and residual disease remains a precipitating factor for sustained local inflammation, in-stent neo-atherosclerosis and impaired vasomotor function increasing the risk for late complications attributed to late or very late stent thrombosis and late target lesion revascularization (TLR) (late catch-up). The quest for optimal coronary stenting continues by further innovations in stent design and by using biocompatible materials other than cobalt chromium, platinum chromium or stainless steel for engineering coronary implants. Bioresorbable scaffolds made of biodegradable polymers or biocorrodible metals with properties of transient vessel scaffolding, local drug-elution and future restoration of vessel anatomy, physiology and local hemodynamics have been recently developed. These devices have been utilized in selected clinical applications so far providing preliminary evidence of safety showing comparable performance with current generation drug-eluting stents (DES). Herein we provide a comprehensive overview of the current status of these technologies, we elaborate on the potential benefits of transient coronary scaffolds over permanent stents in the context of vascular reparation therapy, and we further focus on the evolving challenges these devices have to overcome to compete with current generation DES. Condensed Abstract:: The quest for optimizing percutaneous coronary interventions continues by iterative innovations in device materials beyond cobalt chromium, platinum chromium or stainless steel for engineering coronary implants. Bioresorbable scaffolds made of biodegradable polymers or biocorrodible metals with properties of transient vessel scaffolding; local drug-elution and future
Percutaneous cholecystolithotomy: is gall stone recurrence inevitable?
Donald, J J; Cheslyn-Curtis, S; Gillams, A R; Russell, R C; Lees, W R
Using radiological interventional techniques the gall bladder can be cleared of stones with a high success rate. As with any treatment option that leaves the gall bladder in situ there is an accompanying risk of stone recurrence, which is currently unknown for the radiological method. One hundred patients were studied prospectively to determine the recurrence rate of stones and clinical outcome after successful percutaneous cholecystolithotomy. Follow up included both clinical assessment and ultrasound examination at 3, 6, and 12 months and then annual intervals thereafter. The overall stone recurrence rate was 31% at a mean follow up of 26 months (range, 3-50 months). By actuarial life table analysis, the cumulative proportion of gall stone recurrence was 7, 19, 28, 35, and 44% at 6, 12, 24, 36, and 48 months respectively. Of the 31 patients with recurrent stones; 17 remain asymptomatic, seven have experienced biliary colic, two abdominal pain, three non-specific upper gastrointestinal symptoms, and two jaundice secondary to common duct stones. Thirteen of the stone free patients have remained symptomatic; six with abdominal pain and seven with nonspecific upper gastrointestinal symptoms. Eight patients have subsequently had a cholecystectomy. No significant difference was found between the sex of the patient or the number of stones before treatment and the stone recurrence rates. The cumulative stone recurrence rate was significantly less in the 56 patients who received adjuvant chemolitholysis (p < 0.05). These data show that stone recurrence after successful percutaneous cholecystolithotomy occurs in the minority, and is usually asymptomatic. It is concluded that the technique remains justified in the management of selected patients with gall stones. PMID:8200568
Percutaneous Surgery for Metatarsalgia and the Lesser Toes.
Redfern, David J; Vernois, Joel
The traditional open surgical options for the treatment of metatarsalgia and lesser toe deformities are limited and often result in unintentional stiffness. The use of percutaneous techniques for the treatment of metatarsalgia and lesser toe deformities allows a more versatile and tailor-made approach to the individual deformities. As with all percutaneous techniques, it is vital the surgeon engage in cadaveric training from surgeons experienced in these techniques before introducing them into his/her clinical practice. PMID:27524704
Intraperitoneal seeding from hepatocellular carcinoma following percutaneous ethanol ablation therapy.
Kurl, S; Farin, P; Rytkonen, H; Soimakallio, S
We present a case of intraperitoneal seeding in a 36-year-old woman with a large primary hepatocellular carcinoma located superfically in the left lobe of the otherwise normal liver. The patient was treated with percutaneous ethanol ablation therapy. Eight months after the treatment computed tomography and ultrasonography (US) revealed an intraperitoneal seeding that was confirmed with US-guided percutaneous biopsy. PMID:9107646