A description is given of a thermo-transfer ribbon having a customary carrier, with a wax-bonded layer of a thermo-transfer color formed on one side of the carrier, and a resin-bonded separation layer located between carrier and wax-bonded layer, characterized in that at least the resin-bonded separation layer A) contains a wax-soluble polymer and the wax-bonded layer B) of the thermo-transfer color contains less than approximately 8% by weight, specifically 0 to approximately 5% by weight, of wax-soluble polymer, whereby the waxes of the wax-bonded layer B) are narrowly cut waxes with melting- and coagulation points positioned in close proximity to each other. The benefits of said thermo-transfer color consist in that there occur no differences in the quality of the print, either with xe2x80x9ccoldxe2x80x9d or xe2x80x9chotxe2x80x9d print, and specifically also on uncoated paper with high degree of roughness.

The invention relates to a thermo-transfer ribbon having a customary carrier with a wax-bonded layer of a thermo-transfer color formed on one side of the carrier and a resin-bonded separation layer arranged between the carrier and wax-bonded layer.
A thermo-transfer ribbon of the above described type is known from DE 195 48 033 A1. The wax-bonded separation layer described in same improves separation of the wax-bonded layer from the respective carrier. It is the particular goal of said teaching to exclude the necessity of forming a so-called xe2x80x9ctop coatxe2x80x9d (adhesive layer) or a dual-layered thermo-transfer color, and to achieve satisfactory matt print-outs during the thermo-print process. This is assured in that both the wax-bonded separation layer as well as the wax-bonded layer of the thermo-transfer color contain a wax-soluble polymer in sufficiently large quantity. It is specifically preferred that the wax-bonded layer of the thermo-transfer color contains approximately 5 to 10% by weight of wax-soluble polymer.
The above described thermo-transfer ribbon is to a high degree suitable for satisfying the addressed goal. However, if the targeted goals are different, it requires improvement. This applies specifically with respect to thermo-transfer print on uncoated paper (xe2x80x9cplain paperxe2x80x9d), which has a comparatively high degree of roughness. The following physical properties are absolutely indispensable for good print quality and for quality products: The force of mechanical anchoring of the thermo-transfer color on the printed paper during separation in the thermo-printerxe2x80x94separation of ribbon from paperxe2x80x94must be greater than the cohesion of the thermo-transfer color itself and the adhesion of the thermo-transfer color to the substrate, i.e. less application of color, low color viscosity and low adhesion of the color vis-a-vis the separation layer (release layer) during the printing process lead to optimal print quality. Furthermore, state of the art products demonstrate that unwelcome variations in print quality occur with a xe2x80x9ccoldxe2x80x9d and xe2x80x9chotxe2x80x9d print head.
The invention is therefore based on the object of suggesting a thermo-transfer ribbon of the above-identified type, with which the earlier addressed goals are achieved with respect to improvement of the print quality, specifically with xe2x80x9ccoldxe2x80x9d or xe2x80x9chotxe2x80x9d print, specifically also on uncoated paper having a high degree of roughness.
According to the invention, said object is solved in that at least the resin-bonded separation layer A) contains a wax-soluble polymer and that the wax-bonded layer B) of the thermo-transfer color contains less than approximately 8% by weight, specifically approximately 0 to 5% by weight of wax-soluble polymer, whereby the waxes of the wax-bonded layer B) constitute narrowly cut waxes with melting- and coagulation points separated by only a narrow gap. Consequently, the wax-bonded layer B) contains no significant amounts of wax-soluble polymer, specifically approximately 0 to 1.5% by weight or even less than approximately 0.5% by weight.
In the present specialized field, the term xe2x80x9cseparation layerxe2x80x9d or xe2x80x9crelease layerxe2x80x9d means a layer which regulates the transfer of thermo-transfer color to the receiving substrate during the printing process, but which itself is not being transferred to the substrate. A separation layer does not melt during the printing process, but which, at most, softens and has, in addition, high adhesive property vis-a-vis the carrier.
One essential aspect with respect to solving the identified object is the use of xe2x80x9cnarrowly cutxe2x80x9d waxes in the wax-bonded layer, in other words, melting point and coagulation point must lie close together. The temperature difference between melting point and coagulation point is in this case less than approximately 10xc2x0 C., specifically less than approximately 7xc2x0 C. and, most particularly preferred, less than approximately 5xc2x0 C.
The waxes employed within the scope of the invention in the wax-bound layer B) of the thermo-transfer color are in line with the customary definition for wax, subject to the above limitation of restriction to narrowly cut waxes. Waxes with a melting point of approximately 75 to 90xc2x0 C. are specifically employed within the scope of the invention. In the broadest sense, this involves material which is solid to brittle hard, coarse to finely crystalline, transparent to opaque, of relatively low viscosity without being stringy just slightly above the melting point. Waxes of this type are classified as natural waxes, chemically modified waxes and synthetic waxes.
Specifically preferred among the natural waxes are vegetable waxes in form of carnauba wax, candelilla wax, mineral waxes in form of higher-melting ceresin and higher-melting ozocerite (earth wax), petro-chemical waxes, such as for example petrolatum, paraffin waxes and micro-waxes. Preferred among the chemically-modified waxes are in particular montan-ester waxes, hydrated castor oil and hydrated jojoba oil. Preferred among the synthetic waxes are polyalkylene-waxes and polyethylene-glycol waxes, including products made from same via oxidation and/or esterification. Amide-waxes can likewise be utilized. To be mentioned here as particularly preferred are modified micro-crystalline waxes.
The melting point parameters to be observed for the utilized waxes according to the invention is critical. If the value falls below 70xc2x0 C. that means that the mechanical anchoring is inadequate and color transfer and color resolution fail to satisfy. Higher melting points than approximately 95xc2x0 C. adversely result in higher energy expenditure during the printing process.
The carnauba wax constitutes a good example for an employable wax according to the invention, with melting point at approximately 85xc2x0 C. and coagulation point at approximately 78xc2x0 C.
The specified waxes result in desirable low cohesion during the printing process of the thermo-transfer color. Multiple additives can be incorporated into the wax materials of the wax-bonded thermo-transfer color, such as specifically tackifiers in form of terpene phenol resins (such as, for example, the commercial products Zonatac lite 85 made by Arizona Chemical) and hydrocarbon resins (such as, for example, the commercial products KW-resin 61 B1/105 made by VFT, Frankfurt).
An adhesive layer with tackifier can be applied on layer B). In one specific embodiment, an adhesive layer is positioned on layer B), specifically a paraffin layer with a contents of finely distributed tackifying hydrocarbon resin, with the paraffin having a melting point of specifically 60 to 95xc2x0 C.
Tinting can be done by any coloring substances. These may involve pigments, at a temperature of 100xc2x0 C., such as specifically carbon black, but also solvent-soluble and/or binder-soluble coloring substances, like the commercial product Basoprint, organic color pigments as well as various azo dies (Cerces- and Sudan dies). Carbon black is considered as particularly suitable within the scope of the present invention. The thermo-transfer color preferably contains the coloring substance, specifically pigment, in a volume of approximately 5 to 20% by weight. The melting point of the wax-bonded thermo-transfer color lies generally between approximately 60 and 80xc2x0 C.
The thermo-transfer color of the above specified layer B) of the thermo-transfer ribbon according to the inventionxe2x80x94if applicable with the aforementioned additivesxe2x80x94preferably has a viscosity of approximately 50 to 150 mPaos, specifically of 70 to 120 mPaosxe2x80x94determined at a temperature of 100xc2x0 C. with a rheograph by means of rotation viscometer Rheomat 30 (Principle: rotation viscometer, see Bulletin T-304d-7605 of Messrs. Contraves AG Zuerich/Switzerland). Falling below the value of approximately 50 mPaos results in loss of sharpness (xe2x80x9cspreadingxe2x80x9d). If the value of 250 mPaos is surpassed, deterioration with respect the desired resolution may occur.
A central characteristic of the thermo-transfer ribbon according to the invention consists in that layer A) mainly contains a wax-soluble polymer. The term xe2x80x9cwax-solublexe2x80x9d in this context means that this polymer is soluble in liquid wax. This does not necessarily involve xe2x80x9cgenuine solutionsxe2x80x9d, but mostly stable dispersions. The result is that during the cooling of such polymer solution in wax, there will be no phase separation or that said polymer is compatible with the wax. The melting index MFI lies at 25 to 1000 g/10 min (220xc2x0 C./2.16 kg) preferably at 400 to 800 g/10 min (DIN 537735/ISO 1133, see also Roempp Chemical Lexicon, Volume 5, 9th edition, page 4036, right hand column). Wax-soluble polymers, according to the sense of the invention, distinguish themselves in that they melt below approximately 100xc2x0 C. and that they are tacky in liquefied state. Suitable polymers are, for example, ethylene-vinylacetate -co-polymers, polyamides, ethylene-alkylacrylate-co-polymers, ethylene-acrylic acid-co-polymers, polyvinyl-ether and polyisobutene, including ionomer-resins. Particularly preferred among these are ethylene-acrylic acid-co-polymers and ethylene-vinylacetate-co-polymers (EVA). With employment of ethylene-vinylacetate-co-polymers, a vinylacetate contents of approximately 16 to 42% by weight is preferred, specifically of approximately 18 to 40% by weight in order to increase the adhesion between the separation layer A) and layer B). The melting index MFI (according to DIN 53735) of the ethylene-vinylacetate -co-polymer should lie above approximately 20 g/10 min, specifically above approximately 30 g/10 min (220xc2x0 C./2.16 kg).
For a low adhesion setting between the separation layer A) and the layer B), the ethylene-vinylacetate-co-polymer preferably has a vinylacetate contents of approximately 3 to 17% by weight, specifically approximately 6 to 12% by weight.
The term xe2x80x9cwax-soluble polymersxe2x80x9d includes also polymers which already show a certain tackiness at room temperature, such as for example poly-isobutenes with oily, tough-sticky to caoutchouc-like consistency. Such products are marketed under the tradename Oppanol (BASF, Germanyxe2x80x94compare Roempp Chemical Lexicon 9th edition, volume 4, page 3121/3122).
Among these, at room temperature sticky, water-soluble polymers are also raw materials on the basis of polyvinylethyl, -methyl, and -isobutylether, which are distributed under the tradename Lutonal (BASF, Germany, compare Roempp Chemical Lexicon, 9th edition, volume 3, page 2566).
A particular characteristic of the present invention is the shifting of the main quantity of the discussed wax-soluble polymer from layer B) to the separation layer A). The wax-soluble polymers can be employed singly or in mixed combination. It is possible to employ identical or different wax-soluble polymers in the separation layer A) and, if present, also in layer B).
In the separation layer A), the wax-soluble polymer is preferably present in a volume of approximately 10 to 60% by weight, specifically approximately 20 to 40% by weight. If the value falls below 10% by weight, then the adhesion of the color layer is too high and there is no assurance with respect to homogeneous color transfer. A value of more than 60% by weight results in insufficient adhesion to the color layer and, consequently, in poor resolution of the printed symbols.
The shifting of the principal volume from the thermo-transfer color to the separation layer of the wax-soluble polymer, specifically in form of ethylene-vinylacetate-co-polymer, produces a relative low viscosity when quite a lot of ester wax (melting point greater than 80xc2x0 C.) is employed. The resulting lower viscosity and good carbon black dispersivity in ester waxes permits higher concentration of pigment, specifically carbon black, and, consequently, lower color application (g/m2) with equal surface cover capability.
The separation layer A) containing the principal portion of wax-soluble polymers also fulfills the function of a xe2x80x9cmatt layerxe2x80x9d. As a result of the matt layer, truly matt print-outs are being produced during the thermo-print process. This is based on the circumstance that it is not only the thermo-transfer color which turns liquid during the printing process, thereby adhering to the substrate, specifically in form of a paper acceptor, but that the separation layer softens as well and retains perceptible adhesion to the color layer, so that for example, full flat transfer of print symbols to the paper acceptor is not possible. Instead, the surface of the printed symbols is roughened a little, so that the surface of the transferred symbols appears matt (dull) as a result of light refraction/light diffusion.
The xe2x80x9cmattingxe2x80x9d effect is further promoted if layer B) contains black pigment and the separation layer additionally contains carbon black, specifically in a volume of approximately 20 to 50% by weight, which results in the used-up thermo-transfer ribbon affording sufficient data protection. With this beneficial embodiment of the present invention, silicic acid and auxiliary dispersants are preferably also incorporated into the separation layer. As a result, the carbon black remains finely distributed in the layer during the formation of the layerxe2x80x94it does not settle down.
In another embodiment the xe2x80x9cprinting noisexe2x80x9d can be regulated by addition of polyether-alcohols to the separation layer A) (release of the ribbon from the paper after the printing process). For that purpose, the separation layer A) contains separation substances in volume of approximately 5 to 30% by weight, whereby said substances are present in form of non-ionic tensides, emulsifying agents, polyethylene-glycoles, etc.
The application thickness of the separation layer A) and of layer B) is not critical. The separation layer A) preferably has an application thickness of approximately 0.2 to 5 g/m2, specifically approximately 1 to 3 g/m2, and layer B) an application thickness of approximately 1.0 to 10 g/m2, specifically approximately 3 to 6 g/m2. With respect to the separation layer A), this is a resin-bonded layer, whereby the resin binding agent is preferably a solid resin, having a softening range within the framework of approximately 50 to 200xc2x0 C. The resin preferably comprises alkyd-, epoxide-, melamine-, phenol-, urethane- and/or polyester or co-polyester resins and/or a polyamide, hydrocarbon resin, natural resin, polyvinylether and/or polyisobutene.
The carrier of the color ribbon according to the invention is not critical. Polyethylene-terephthalate foils (PETP) or capacitor tissues are preferably used as basic foil for the thermo-transfer ribbons.
The selection parameters are highest possible tension/elongation values and thermal stability with small foil thickness. PETP foils can be obtained as thin as approximately 2.5 xcexcm, capacitor paper as thin as approximately 6 xcexcm. During the printing process, the thermo print head reaches temperatures of up to 400xc2x0 C., i.e. temperatures which lie above the softening point of PETP. If PETP foils are employed, it is suggested that a layer of particularly heat-resistant material be provided on the reverse side of the foil that comes into contact with the thermo head.
A beneficial refinement of the inventive idea, specifically for obtaining a beneficially sharp-edged print, is based on an incorporation of the teaching of EP-B-0 133 638. Accordingly, on the reverse side of the carrier, a layer is formed made of wax or a wax-like material, specifically with a thickness of not more than approximately 1 xcexcm and most specifically preferred in form of a molecularly shaped layer, having a thickness of approximately 0.05 to 0.10 xcexcm. The coating material in this case preferably consists of paraffin, silicone, natural waxes, specifically carnauba wax, bees wax, ozocerite and paraffin wax, synthetic waxes, specifically acid waxes, ester waxes, partially saponified ester waxes and polyethylene waxes, glycoles or polyglycole, antistatic substances and/or tensides. If such coating is provided on the reverse side, then undisturbed heat transfer takes place from the thermo print head to the thermo-transfer ribbon, resulting in particularly sharp-edged prints.
For obtaining optimal print quality when employing the thermo-transfer ribbon according to the invention in fax machines, it is suggested that a so-called four-layer-structure be developed in the following sequential order and with the approximate following layer thickness: Top coat (adhesive layer) approximately 0.5 to 0.7 g/m2, wax-bonded layer of the thermo-transfer color B)xe2x80x94approximately 4.0 to 4.5 g/m2, separation layer A)xe2x80x94approximately 0.5 to 1.0 g/m2, thickness of the carrier (for example polyethylene-terephthalate) approximately 4.0 to 5.0 xcexcm, reverse side coating (anti-adhesive layer) approximately 0.05 to 0.1 g/m2. In order to concurrently obtain higher temperature resistance during storage, it is appropriate to work into the thermo-transfer color and with respect to the four-layer product into the top coat, a higher melting wax having a melting point of at least 80xc2x0 C., specifically  greater than 85xc2x0 C.
The thermo-transfer ribbon according to the invention described above can be manufactured in many ways using customary application processes. It can be done, for example, by spraying on or printing on a solution or dispersion, either with water or an organic solvent as dispersion or dissolution agent, by application from melted state, which applies particularly with respect to the wax-bonded thermo-transfer color, or also by normal application via wiper-blade in form of a watery suspension with finely distributed coating material therein.
From an environmental protection aspect, the following method has been proven as particularly beneficial: To start with, a watery suspension of the raw materials of the separation layer are applied in a thin coating on the carrier, which, upon evaporation of the water, permits the formation of the separation layer A). The formation of the separation layer A) is followed by an application of a watery suspension of the raw material of the wax-bonded thermo-transfer color, with the water being evaporated in customary fashion, after application of this material. The developed double-layered coating satisfies all requirements within the scope of the specified object. It is, however, also possible to apply the thermo-transfer color onto the separation layer in form of melted material according to customary application technologies, for example with a wiper-blade. The temperature of the respective melt should generally range between 100 and 130xc2x0 C. After the coating, the applied materials are permitted to simply cool down.
For the practical or particularly beneficial realization of the present invention, the following basic conditions can be specified with respect to application volumes of the individual layers or their application thickness: Thermo-transfer layer B) approximately 1 to 10 g/m2, preferably approximately 3 to 6 g/m2, separation layer A) 0.2 to 5 g/m2, preferably approximately 0.5 to 1.5 g/m2, carrier film, specifically polyester film with a thickness of approximately 2 to 8 xcexcm, specifically with a thickness of approximately 4 to 5 xcexcm, including reverse side coating with an application thickness of approximately 0.01 to 0.2 g/m2, specifically of approximately 0.05 to 0.1 g/m2.
The benefits related to the invention must be seen specifically in that the beneficial prints can also be made on uncoated and consequently rough paper, whereby higher resolution is achieved, specifically when employed in fax machines. There is no difference in the quality of the print with either xe2x80x9ccoldxe2x80x9d or xe2x80x9chotxe2x80x9d print. Other benefits with respect to the thermo-transfer ribbons accrue from enhanced temperature resistance and improved shelf-life (T greater than 50xc2x0 C. ), as well as reduced print noise and from the 100% antistatic finish resulting from embedding conductive carbon black into the separation layer. These benefits are specifically obtained in that the wax-soluble polymer,xe2x80x94specifically the preferably employed ethylene-vinylacetate-co-polymerisatexe2x80x94is shifted from the thermo-transfer color B) into the separation layer A) and that with the aid of incorporating separation means into the separation layer A), control of print noise is achieved.


Methods of using high-density microparticles to bind and remove pathogens from biological fluids are disclosed. Pathogens include prions, viruses, bacteria and protozoa.

This invention relates to methods for separating and isolating pathogens from biological fluid samples such as blood and blood components by means of high density microparticles.
Whole blood includes cellular (erythrocytes or red blood cells, leukocytes or white blood cells, thrombocytes or platelets) along with non-cellular components (plasma). When blood is collected from a donor for use, the whole blood is typically separated by centrifugation into such components, which can then be used therapeutically, rather than administering whole blood, in order to maximize the clinical and economic utility of blood. The leukocytes present in whole blood are often carried during processing into each of the blood components. Leukocytes may transmit infectious agents, such as cell-associated viruses (e.g. cytomegalovirus or human immunodeficiency virus) or they may cause adverse immunological reactions, such as alloimmunization. For those reasons, leukocyte removal is often desirable and several methods have been developed to remove leukocytes without causing appreciable damage to the blood or blood component. See for example, Coulter, et al., U.S. Pat. No. 5,576,185 and Pall, et at., U.S. Pat. No. 5,229,012.
However, other pathogenic substances may still be present in whole blood or its various components, that can be harmful to a patient receiving such blood. This is of particular concern when the patient is immune compromised and more susceptible to pathogens that may be present in the blood. Such pathogens include viruses, protozoa and bacteria. In addition, more recently, concern has arisen over prions, which are protein agents believed to be capable of transmitting spongiform neuropathies such as Creutzfeld Jacob""s Disease. Experimental evidence in animals suggests that these agents may be transmitted by blood transfusions (Houston et al., Lancet 356(9234): 999-1000, 2000), and concern over transmission of these agents has resulted in recall of some human blood-derived products.
Although substantial removal of some pathogens such as cell-associated viruses may occur during leukocyte removal, there is a continuing need to develop more quantitative and broader methods of removing such pathogens from whole human blood and blood components, while maintaining the integrity of the blood.
One method of eliminating pathogens is by inactivation, for example, by directly or indirectly inhibiting the virus""s ability to replicate. Reichl, U.S. Pat. No. 5,633,349 describes the inactivation of prions, viruses and other infectious agents by treatment with a chaotropic agent such as urea or sodium thiocyanate. Use of a chaotropic agent for treatment of blood cells has the undesired consequence of destroying the therapeutic utility of the resulting cellular product. Miekka, et at., U.S. Pat. No. 6,106,773 relates to the use of an iodinated matrix to disinfect biological fluids by inactivating pathogens contained therein. Cook et at., PCT/US98/00532 describes the use of frangible compounds for chemical inactivation of pathogens by targeting nucleic acids. Other inactivation methods use photoactivation, which is a combination of a photochemical agent and light. Such agents include psoralens (Lin, et at., U.S. Pat. No. 5,459,030), methylene blue (Wolf, Jr., et at., U.S. Pat. No. 5,527,704) and phthallocyanines (Horowitz, et at., U.S. Pat. No. 5,637,451).
Inactivation is not uniformly successful in eliminating pathogens since some are not susceptible to inactivation under conditions that preserve the therapeutic or diagnostic usefulness of a biological fluid. The Hepatitis A virus is a small non-enveloped, blood borne virus that resists inactivation by detergents, heat and most small-molecule chemical and photochemical inactivating agents. Prions are another example of a pathogen that resists inactivation by almost all forms of sterilizing treatment, including heat, ionizing radiation, and chemical treatments. In particular, because prions lack nucleic acids and form an extraordinarily stable protein structure, they are generally resistant to practical methods of inactivation. For agents such as these, a removal method that also preserves the therapeutic or diagnostic utility of the biological fluid is clearly desirable.
Methods of removing pathogens also include physical separation techniques such as by filtration or chromatography. Wick, et at., U.S. Pat. No. 6,051,189 relates to the detection and extraction of submicron particles such as viruses and prions, by centrifligation and ultrafiltration. Gawry, et al., U.S. Pat. No. 5,808,011 describes a method of prion removal using an anion exchange chromatographic column under conditions that cause a gradient elution.
Physical separation techniques often use magnetic particles. For example, Giaever, et at., U.S. Pat. No. 3,970,518 describes the use of antibody-coated magnetic particles to separate select cells, bacteria or viruses from multi-cell, bacteria or virus populations. Magnetic particles are available in various sizes and can be either non-uniform (Josephson, U.S. Pat. No. 4,672,040) or very uniform (Homes, et at., U.S. Pat. No. 5,512,439). Magnetic particles are generally  less than 4.5 xcexcm in diameter and have a density of  less than 1.8 g/cm3. The magnetic microspheres are intended to be maintained in suspension in the sample and consequently are designed not to settle by gravity.
Non-magnetic, physical separation methods have also been used to separate various cell components from samples of whole blood or bone marrow. Coulter, et at., U.S. Pat. No. 5,576,185, describes the use of reactant-coated, high density microparticles that separate under gravity, a mechanism that allows for separation of undesired cells without substantially physically damaging the blood cells. The advantages of high density microparticles over magnetic particles in the area of cell separation are well established. However, until now, no one has attempted to apply this technology for removal of cellular pathogens such as viruses, bacteria and non-cellular pathogens such as prions.
The invention provides a novel method for separating pathogens from a biological fluid sample. A plurality of high density microparticles (xe2x80x9cHDMxe2x80x9d) having a reactant such as an anti-pathogen antibody, bound thereto are mixed with the sample. The HDM, with the pathogen bound thereto, are allowed to differentially settle by gravity and the remaining sample is removed.
One aspect of the invention pertains to a method of removing at least one population of target pathogens from a biological fluid sample, comprising: providing a plurality of high density microparticles having bound thereto a reactant which specifically binds to the target pathogen, and having a density sufficient to provide differential gravity settling of the target pathogen from the sample; mixing a portion of the sample with the microparticles to bind the microparticles to the target pathogen; settling the microparticles with the bound pathogen in the sample to produce a supernatant substantially free from the bound pathogen, where the settling is accomplished primarily by gravity; and separating the microparticles bound to the pathogen from the supernatant.
The term xe2x80x9chigh density microparticlesxe2x80x9d or xe2x80x9cHDMxe2x80x9d is used to mean particles having a density greater than that of the non-target materials present in the sample, so that the HDM are able to settle out of the sample by differential gravity, i.e., the HDM will settle more rapidly than the non-target materials. Typical xe2x80x9cnon-targetxe2x80x9d materials include red blood cells or white blood cells, platelets, plasma proteins and so forth. Clearly, the greater the differences in density between the HDM and the non-target materials present in the sample, the faster the differential settling will occur. Preferably the particles have a density of at least twice, more preferably 2 or 3 times the density of the non-target materials present in the sample. In particular, HDM preferably have a density greater than 2 g/cm3, typically on the order of 7-10 g/cm3. Preferably the HDM are nickel, which has a density of about 9 gm/cm3.
The term xe2x80x9csamplexe2x80x9d is intended to mean the substance to be analyzed or used therapeutically, where the substance is either a fluid itself or is suspended in a fluid medium. The sample is typically a biological fluid, which includes by means of illustration and not limitation, whole blood or a component thereof such as plasma, a platelet-enriched blood fraction, a platelet concentrate or packed red blood cells; cell preparations such as dispersed tissue, bone marrow aspirates or vertebral body bone marrow; cell suspensions; urine, saliva and other body fluids; bone marrow; spinal fluid; and so forth. The sample can also be a lysed preparation, such as cell lysates, which can be formed using known procedures such as the use of lysing buffers, and so forth. The volume of the sample used in the methods of the invention will vary depending upon the particular application. For example, when the method is being used for a diagnostic or research application, the volume of the sample will typically be in the microliter range, and can be 10 xcexcl or greater. When the method is being used for a therapeutic application such as for clinical transplantations, the volume of the sample will typically be in the milliliter to liter range, for example, 100 milliliters to 3 liters. In an industrial application, such as purification of pooled donor plasma, the volume may be tens of thousands of liters.
The term xe2x80x9cpathogenxe2x80x9d is intended to include any biological organism that is harmful to humans and includes, by way of illustration and not limitation, non-cellular pathogens such as prions, including classical CJD and new variant CJD; protozoa such as giardia; viruses such as Human Immunodeficiency Virus, Herpes Simplex Virus, Epstein Barr Virus, cytomegalovirus, T-cell lymphotrophic virus, varicella zoster virus, adenovirus, Hepatitis A virus, Hepatitis B virus, Hepatitis C virus, human B-19 parvovirus, Nipah virus, hantaviruses, yellow fever virus (family Flaviviridae or Flavivirus) the tick-borne hemorrhagic fever viruses, or the tick-borne encephalitis viruses; cellular pathogens such as bacteria, which include, for example, streptococcus, diptheria, mycobacterium, treponema, Yersinia enterocolitica, Klebsiella pneumoniae, Pseudomonas aerugonisa, Staphylococcus, aureus, Bacillus anthracis (causative agent of anthrax), Clostridium botulinum and its toxins (causative agents of botulism), Yersinia pestis (causative agent of plague), Variola major (causative agent of smallpox), Francisella tularensis (causative agent of tularemia), Coxiella burnetti (causative agent of Q fever), bacteria of the genus Brucella (causative agents of brucellosis) Burkholderia mallei (causative agent of glanders), Ricinus communis and its toxins, Clostridium perfringens and its toxins, such as the epsilon toxin, Staphylococcus toxins, such as enterotoxin B, bacteria which cause multidrug resistant tuberculosis such as drug-resistant Mycobacterium tuberculosis strains, or other pathogenic bacteria known to be transmitted by biological fluids; fungi such as such as candida; and parasites such as plasmodium, ascaris, leishmania, and Trypanosoma cruzi. The term xe2x80x9ctarget pathogenxe2x80x9d refers to the pathogen of interest that is to be removed from the sample.
The term xe2x80x9cpathogen removalxe2x80x9d means the substantial reduction of the number of pathogenic particles from a biological fluid as measured by a biological, chemical or physical titration assay. Pathogen removal is usually measured as a logarithmic function, for instance a 1-log removal indicates that starting titer of the pathogen has been reduced by 90%. A 2-log removal indicates a reduction by 99%, and so on. Substantial reduction of a pathogen can include removal of 1- to 3-logs or greater, and preferably results in greater than 4- to 5-logs of removal or a final titer below the limit of detection of the pathogen assay. Pathogen detecting assays include physio-chemical assays, for instance a fluorescence assay, or biochemical assays, for instance an ELISA assay. Pathogen detecting assays may involve the in vitro use of cells such as viral plaque assays or microbial growth assays. For some pathogens, the only appropriate endpoint is an in vivo titration assay since the pathogen only replicates in a particular host animal. These and other methods known to those in the art may be used for measuring pathogen removal.
The present invention is based on the finding that high density microparticles (xe2x80x9cHDMxe2x80x9d) offer advantages over other solid supports, primarily magnetic particles, for the removal of pathogens from biological fluids. While not being limited to a particular mechanism, the density of the HDM is such that during mixing, the HDM contact the target pathogen in the sample at rates greater than by classical diffusion because the particles are moving through the solution under the influence of gravity, thus leading to the need for significantly fewer particles than used in state of the art methods, and more effective and rapid mixing. This results in a more cost-effective reagent and significantly lower non-specific binding due to the lower surface area. xe2x80x9cSurface areaxe2x80x9d refers to the area of the particle surface available for reaction, and fewer particles translates to lower surface area per reaction.
Additional advantages of the instant invention include: rapid reaction kinetics (speed of target pathogen capture), lack of requirement for ancillary devices such as a magnetic separator, simplicity of rinsing and adding of reagents and of particle separation, and economy of reagents because the speed of capture is such that significantly fewer particles are required than with magnetic separation as noted above. Further, the use of gravity settling to separate the particles is far less vigorous and time consuming than traditional separation techniques such as centrifugation which generates shear forces, which can degrade desirable materials present in the biological fluid.
A further advantage of the method of the invention is that the method does not cause substantial cell damage and preserves the function of the sample. This is of particular concern when the sample is a biological fluid such as whole blood or a component thereof which is intended for therapeutic use. Preservation of function can be assessed readily based on the intended use by one skilled in the particular art and accepted medical practice defines a large range of cellular, biochemical and physical properties of blood cells that are therapeutically acceptable. For instance, regulatory standards of product approval recognize that blood cells with far less than 100% activity may be therapeutically useful. For instance, 24-hour post transfusion recovery of red blood cells as low as 70% after processing and storage has been deemed an acceptable value for therapeutic use. After depletion of pathogens in a red blood cell suspension, the function of the red blood cells can be measured using standard in vitro methods, including hemolysis, ATP levels, cellular deformability and pH. The functionality of red blood cells can also be measured in vivo by determining the 24-hour post-transfusion recovery in human subjects. Similarly, platelet recoveries 24-hour post transfusion of 30-50% are considered routine and acceptable in transfusion medicine. Platelet function can be measured by standard in vitro tests including aggregation assays, pH, shape change, osmotic shock and morphology, as well as by in vivo determination of the 24-hour post transfusion recovery. Hematopoietic stem cells can be enumerated via flow cytometry and their viability determined by dye exclusion methods, and their proliferative potential by colony-forming assays.
The present invention relates to methods of using high density microparticles (xe2x80x9cHDMxe2x80x9d) to separate or isolate target pathogens by gravity sedimentation. In one embodiment of the invention, the HDM are first added to the sample in a mixing step. Following the mixing step, the sample is simply stood on end and the HDM bound to the target pathogen, settle out by gravity, typically over a one to four minute time period. A unique feature of the methods of the invention is that the gentle settling of the HDM by gravity is such that the fluid is pushed aside by the falling HDM thus eliminating non-specific trapping of undesired materials and other cellular components by the HDM. This represents a significant improvement over use of magnetic particles where nonspecific trapping occurs as the particles traverse through the fluid toward the magnet.
The HDM can be made of numerous materials, including by way of illustration and not limitation, metals such as iron, nickel, aluminum, copper, zinc, cadmium, titanium, zirconium, tin, lead, chromium, manganese and cobalt; metal oxides and hydrated oxides such as aluminum oxide, chromium oxide, iron oxide, zinc oxide, and cobalt oxide; metal silicates such as of magnesium, aluminum, zinc, lead, chromium, copper, iron, cobalt, and nickel; alloys such as bronze, brass, stainless steel, and so forth. The microparticles can also be made of non-metal or organic materials such as cellulose, ceramics, glass, nylon, polystyrene, rubber, latex, and so forth. The microparticles can also be a combination of a metal and a non-metal or organic compound, for example, methacrylate or styrene coated metals and silicate coated metals. The base material may be doped with an agent to alter its physical or chemical properties, for instance the inclusion of rare earth oxides in aluminosilicate glasses to create a paramagnetic glass materials with high density (White and Day (1994) Rare Elements in Glasses, Key Engineering Materials Vol. 94-95:181-208.)
Suitable commercially available HDM, include for example, nickel (Type 123, VM 63, 18/209A, 10/585A, 347355 and HDNP sold by Novamet Specialty Products, Inc., Wyckoff, N.J.); 08841R sold by Spex, Inc.; 01509BW sold by Aldrich), stainless steel (P316L sold by Ametek), zinc dust (Aldrich), palladium (D13A17 sold by John Matthey Elec.), TiO2, SiO2 or MnO2 (Aldrich).
As noted above, the HDM have a density of at least twice, more preferably 2 or 3 times the density of the non-target materials present in the sample. In this manner, the HDM are designed to settle under gravity and thus be separated them from the non-target materials. For example, the non-target materials commonly include blood cells, which have a density on the order of 1.05 gm/cc. Therefore, for the preferred methods of the invention, the HDM should be substantially more dense than the blood cells, e.g., as stated above, on the order of 2-3 times more dense than the blood cells.
The configuration of the HDM can vary from being irregular in shape to being spherical, from having an uneven or irregular surface to having a smooth surface, and can be finely divided powders or ultrafine particles. The particle size (nominal diameter) is not critical to the invention but will typically range from 1-50 xcexcm, more typically 3-35 xcexcm, and is preferably about 5 xcexcm. The microparticles can be uniform in size or can vary in size with the average particle size preferably being in the aforementioned range.
The shape of the HDM also may be useful in that removal of a specific pathogenic protein in a mixed cellular-plasma fluid characteristic of blood, a spherical component moves through the fluid more efficiently, and minimizes entrapment of cellular components.
Size specificity also can be determined by the target pathogen, where cellular targets may be removed by particles which preferably are 1 to 5 microns in size.
In one embodiment, the HDM have a surface area of at least 0.4 m2/g, preferably from about 0.4 m2/g to about 0.5 m2g.
The preferred HDM are formed from carbonyl nickel, such as the nickel powders made by Novamet, a subsidiary of INCO, USA, as Nickel Powder Type 123. The microparticles are not uniform in size, but have a size range of 3-35 xcexcm, with a nominal diameter of about 5 xcexcm.
The aforementioned particle materials are intended to be illustrative only and are not intended to be limiting in any manner, since any particle material, along with any particle size or configuration, can be used as long as the microparticles settle by differential gravity as required by the invention.
The HDM are linked to a reactant and are preferably coated before being linked to the reactant. Numerous coatings as are well known in the art can be utilized, for example the microparticles can be coated with human serum albumin, tris (3-mercaptopropyl)-N-glycylamino) methane (Siiman, et at., U.S. Pat. No. 6,074,884), gelatin-aminodextrans (Siiman, et at., U.S. Pat. No. 5,466,609) or amino acid homopolymers or random copolymers. A preferred random amino acid copolymer is poly(glutamate, lysine, tyrosine) [6:3:1] obtainable from Sigma Chemical Co. as Product No. P8854. It is a linear random polymer of the amino acids glutamic acid, lysine, and tyrosine in a ratio of 6 parts glutamic acid, 3 parts lysine, and 1 part tyrosine. In another embodiment, the amino acid copolymer is an amino acid copolymer including lysine and tyrosine in a ratio of 4 parts lysine to 1 part tyrosine. In yet another embodiment, the amino acid copolymer is an amino acid copolymer including lysine and alanine in a ratio of 1 part lysine to 1 part alanine. Such coatings will be selected with a view to optimal reactivity and biocompatibility, according to the need of the biological fluid to be treated. Another suitable coating involves first coating the HDM with a synthetic polymer, and then activating the polymer prior to linkage with the reactant. For example, the HDM can have a thin coating of hydrated silica (xe2x80x9csilicatexe2x80x9d) or a silicate derivative, obtained by a process referred to as xe2x80x9csilanolizationxe2x80x9d which uses sodium metasilicate and ammonium acetate. An aqueous solution of sodium/metasilicate is formed, ammonium acetate is added, followed by the addition of the particles to be coated.
It may be desirable to pre-treat the microparticles prior to coating. Such pre-treatment of the nickel microparticles serves to sterilize and depyrogenate and also creates an oxide layer on the particle surface. Typically, such pre-treatment involves heating the nickel microparticles for about 2-6 hours, preferably for about 5 hours, at a temperature within the range of about 200-350xc2x0 C., preferably about 250xc2x0 C. This pretreatment is particularly beneficial when metallic microparticles are used.
The reactant is a molecule capable of binding with the requisite affinity and specificity to the target pathogen. Suitable reactants include monoclonal and polyclonal antibodies (including antibody fragments) that specifically bind to the target pathogen, or synthetic molecules designed or selected to have high affinity for target pathogens. Synthetic molecules can be produced using directed chemical synthesis, combinatorial chemistry or biological methods (e.g. phage display) followed by screening, as is know to those skilled in the art. Depending on the complexity of the library of products generated using a combinatorial method, screening may involve automated, high throughput methods or may utilize a biological selection for identifying the desired ligand. The term xe2x80x9cspecifically bindxe2x80x9d refers to the specific affinity of the reactant for the target pathogen compared to the substantially reduced affinity for other macromolecules, pathogens or cells.
As indicated above, the present invention relates to methods of using HDM to separate or isolate target pathogens by gravity sedimentation, using coated microparticles, coupled to a reactant, preferably an antibody, and used to specifically remove or isolate certain targeted pathogens such as prions, protozoa, viruses, bacteria, fungi, parasites, and so forth.
The reactant can be directly attached to the HDM by adsorption or by direct chemical bonding such as by means of a covalent reaction, for example as described in Hermanson (1996) Bioconjugate Techniques New York: Academic Press. The ligand itself may be directly activated with a variety of chemical functionalities including nucleophilic groups, leaving groups, or electrophilic groups. Activating functional groups include alkyl and acyl halides, amines, sulfhydryls, aldehydes, unsaturated bonds, hydrazides, isocyanates, isothiocyanates, ketones, and other groups known to activate for chemical bonding. Alternatively, the HDM and ligand may be bonded through the use of a small molecule coupling reagent. Non-limiting examples of coupling reagents include carbodiimides, maleimides, N-hydroxysuccinimide esters, bischloroethylamines, bifunctional aldehydes such as glutaraldehyde, anyhydrides and the like. Alternately, the reactant may be coupled to the HDM through affinity binding such as a biotinstreptavidin linkage or coupling, as is well known in the art. Where biotinstreptavidin coupling is preferred, streptavidin can be bound to the microparticles by covalent or non-covalent attachment and the biotinylated reactant can be synthesized using methods that are well known in the art. See for example, Hermanson (1996) Bioconjugate Techniques New York: Academic Press. Once the reactant is attached to the HDM, the HDM can be added directly to the fluid sample without further dilution or washing steps.
For covalent binding, the HDM may be coated with a polymer that contains chemical moieties or functional groups that are available for covalent attachment to a suitable reactant, typically through a linker. For example, the amino acid polymers described above may have groups, such as the xcex5-amino group of lysine, available to couple the reactant covalently via appropriate linkers.
The invention also contemplates placing a second coating on the microparticles to provide for these functional groups. Functional groups by which the reactant can be attached to the microparticles, are well known in the art and include all those functional groups known to be useful for attaching nucleic acids to solid supports. These include, by way of illustration and not limitation, amino, hydroxyl, carboxyl, aldehyde and sulfhydryl groups. The available functional groups may be further modified to create new functionality. For instance, carboxylates may be converted to primary amines using diamines such as ethylene diamine; carbohydrates and other biological moieties containing polysaccharides may be functionalized to contain aldehyde groups by periodate oxidation; amines may be reacted with 2-iminothiolane to form sulfhydryl groups; hydroxyl groups may be converted to carboxylate moieties using chloroacetic acid. These methods are but a small number of the means known to those of skill for creating new functionality on the HDM or coated HDM (Hermanson, supra).
A plurality of dense, relatively heavy microparticles having the appropriate reactant bound thereto are mixed with the biological fluid sample. The HDM capture the target pathogen rapidly and are then allowed to differentially settle by gravity thus separating the target pathogen(s) from the remainder of the reaction mixture. One advantage of the instant invention is that the methods described herein are particularly adaptable to automation since both the mixing and settling steps can be easily automated. Automation is particularly desirable when the methods of the invention are used in diagnostic applications.
One embodiment of the method of the invention is a method of removing at least one target pathogen from a biological fluid sample. This method can be used to remove more than one population of target pathogens, and they can be removed sequentially or all at one time. The method comprises the following steps: (a) providing a plurality of high density microparticles having bound thereto a reactant which specifically binds to at least one population of target pathogens and having a density sufficient to provide differential gravity settling of the target pathogen from the sample; (b) mixing a portion of the sample with the microparticles to bind the microparticles to the target pathogen; (c) settling the microparticles with the bound pathogen in the sample to produce a supematant substantially free from the bound pathogen, where the settling is accomplished primarily by gravity; and (d) separating the microparticles bound to the pathogen from the supernatant.
The method of the invention also contemplates pretreating the sample by lysis, for example by the addition of lysis buffers.
Mixing Step
The mixing can be effected by passing the microparticles at least once through the sample, such as by gravity. In this manner, the mixing and settling are conducted simultaneously such that mixing is effected solely by differential gravity settling. Therefore, in one embodiment, the method can be performed without any additional mixing step, instead relying only on the microparticles movement though the sample by gravity. When the mixing and settling steps are combined, this mixing/settling will typically take about 1-5 minutes.
The mixing can, however, also be enhanced by causing the microparticles to repeatedly pass or settle through a substantial portion of the sample. For small volumes, on the order of microliters (typically less than 0.5 milliliter), the mixing can be rapid such as by vortexing or xe2x80x9cnutationxe2x80x9d such as is described in Coulter, et al., U.S. Pat. No. 5,238,812, which is incorporated herein by reference. For larger volumes, on the order of greater than or equal to 0.5 milliliters (typically 0.5 ml to 3 liters), mixing can also be achieved by gently tumbling the microparticles and the sample in an end over end fashion such as is described in Coulter, et at., U.S. Pat. No. 5,576,185, which is incorporated herein by reference. Such tumbling can be accomplished, for example, by means of a device configured to hold a test tube or other configuration of a reaction vessel, and which slowly rotates the test tube or vessel end over end. When a separate mixing and settling step are utilized, the mixing step will typically take about 15 seconds to 5 minutes, and the settling step is usually carried out for about 1-4 minutes.
Settling Step
As noted above, the settling aspect of the methods of the invention can be performed relying solely on gravity sedimentation. However, for certain applications, it may be desirable to modify the method to accelerate this step. In one such modification, the HDM and sample are briefly spun in a centrifuge to accelerate the settling step.
Separation Step
Separation of the resulting supematant can be done by numerous methods that are well known in the art such as decanting or siphoning the supernatant, thus leaving the HDM at the bottom of the reaction vessel. For separation of HDM from blood components or other biological fluids, a device commonly referred to as a xe2x80x9cplasma extractorxe2x80x9d may be used to separate HDM from the fluid if a flexible plastic container is used. Automated versions of plasma extractors may also be used.
When the supernatant is intended for therapeutic use, such as by being transplanted in a human, or where for other reasons it is desired to prevent carry over of particles, it may be desirable to use HDM that are comprised of a magnetic material such as nickel. In this manner, a magnet or magnetic field can be applied to the bottom of the reaction vessel after the HDM have settled, to ensure that the HDM are not removed with the supernatant in the separation step.
The HDM may also be of a sufficient size that they can be differentially filtered to separate them from the biological fluid. When the fluid is a non-cellular product, for instance blood plasma, the HDM may have a wide range of sizes. When the fluid contains cells that are desired for later use, the HDM must be sufficiently larger than the cells so that the microparticles can be differentially filtered from the cell suspension. Preferably the HDM in this circumstance have a diameter of at least 7 microns, and more preferably they are 10 microns or greater in diameter in order to be filtered away from the desired cells.
In one embodiment of the invention, the method is used to remove pathogens from a cell preparation, the supernatant of which can be used for clinical transfusion or transplantation, research or diagnostic applications. In a preferred embodiment, the resulting supernatant, substantially free of the contaminating pathogens, is used therapeutically, either in clinical transfusion or transplantation.
Devices for Performing the Methods of the Invention
The methods of the invention for removing at least one population of target pathogens from a biological fluid sample, can be accomplished using separation devices and components as are well known in the art. For example, the cell separation apparatus described in Coulter, et al., U.S. Pat. No. 5,576,185, can be readily adapted for use with the methods described herein. In general, the method of the invention can be practiced using a device that comprises: (a) a plurality of HDM which (i) have bound thereto a reactant which specifically binds to the target pathogen, (ii) have a density sufficient to provide differential gravity settling of the target pathogen from the sample, and (iii) are capable of settling with the bound pathogen in the sample to produce a supernatant that is substantially free from the bound pathogen, where the settling is accomplished primarily by gravity; (b) a means for mixing a portion of the sample with the HDM to bind the HDM to the target pathogen; and (c) a means for separating the HDM bound to the pathogen from the supematant.
Suitable devices would include the biological sample containing the target pathogens and a source of the HDM, along with a container in which the sample and HDM can be mixed and subsequently settle. The device may also include a source of the biological sample, for example a blood donor or a container containing a unit of whole blood or a blood component. The sample can be transferred by tubing to a container such as a primary collection container. This primary collection container is sterile and either holds the HDM or is connected to a second container holding the HDM. Accordingly, the HDM can be added to the primary collection container either before, during or after the transfer of the sample into the container.
After the HDM are dispersed through the sample or have been mixed with the sample, the HDM are allowed to settle to the bottom of the container. The device may also include an expressor that allows for removal of the treated sample from the HDM bound to the target pathogen. The expresser can serve to compress the container thereby reducing its volume and forcing the sample, with the pathogens removed, out of the container. Typically the sample is expressed through a tube to another container, while the HDM with bound target pathogen will generally be retained at the bottom of the container due to their greater density.
The containers used in the methods of the invention, as well as in any devices designed for use with these methods, will be determined by the sample size and can be small, such as a 10 microliter container (e.g., a test tube) or large, such as a 100 milliliter to 3 liter container (e.g., a blood bag). In one embodiment, the containers are sterile and formed from flexible plastic sheeting that is biocompatible with the blood or blood components, such as polyvinyl chloride or polyethylene or other materials known to those skilled in the art of making blood storage containers.
The sample container, the HDM as well as other components of the apparatus that contact the sample directly can be sterilized by controlled heat, ethylene oxide gas or by radiation. The preferred method of sterilization will be selected by one skilled in the art to preserve the activity of the HDM, particularly the reactant bound thereto, and will be dependent on the physical characteristics, composition and number of HDM. Preferred sterilization methods will also depend on whether the device is xe2x80x9cdry,xe2x80x9d that is lacking a solution component, or xe2x80x9cwet.xe2x80x9d Alternatively, it is well known to those skilled in the art of making sample (e.g., blood) storage containers that individual incompatible components can be separately sterilized by different means and then joined via a sterile connection process that connects two devices via sterile tubing leads. The preferred method of sterilization will be a terminal sterilization at the 10-6 Sterility Assurance Level in order to enable extended storage of the sample after processing in the apparatus.
The apparatus may optionally include a secondary means for insuring the separation of the sample from the HDM with bound target pathogen. The purpose of the secondary capture step is to further reduce the probability that HDM will be found in the treated sample, which is of particular concern when the final processed sample is a blood component(s). The nature of this secondary capture will take advantage of specific properties of the HDM. When HDM are used that are made of or incorporate a magnetized or paramagnetic substance, the device may include a magnet or a magnetic field, positioned such that it can be applied to the bottom of the container to either accelerate settling or to insure complete that the HDM are not removed during separation step, in particular when the treated sample is to be reinserted into a living organism, such as the human body. The expressor may also be used in combination with the magnet, or if the container is more rigid, the container may be rotated with the magnet held at the bottom, to allow the treated sample to pour or drain. Alternately, the magnet or a magnetic field can be positioned such that the sample can be passed by or through a magnetic field after it is separated from the HDM, but before it is reinserted into the body. This will also serve to insure that no HDM remain in the sample.
The device can also include an optional secondary means of retaining the HDM during the decanting process, which relies on the size or rigidity of the HDM relative to the sample. If the more rigid HDM are large relative to the red blood cell, for example 10 microns in diameter or greater, they may be retained by a sizing filter placed at the outlet of the container. In particular since red blood cells are known to be highly flexible, the size differential to achieve the separation of the more rigid particles may not need to be large, i.e. the HDM and the red blood cells may in fact be of comparable size.
Another optional secondary means of retaining the particles is to compact the HDM by centrifugation after settling. In this manner, the device may include a centrifuge. The device may include a means for briefly spinning the container, if it is desired to accelerate the settling of the HDM. This could be a centrifuge and would operate simultaneous with settling. In this manner, centrifugation would serve to enhance the rate at which the HDM settle and would also lead to enhanced compaction of the HDM with bound pathogen at the bottom of the container The device can be automated such that the sample and HDM are automatically mixed and then moved between the stations or the device can require manual steps that would be carried out by an operator or can be a combination of the two procedures.
For use of the method of the invention in a large scale, such as in an industrial setting, the HDM can be utilized in a large reaction vessel or fluidized bed reactor or as part of a flow process involving column fractionation.
Another embodiment of the invention is a kit containing a plurality of HDM having bound thereto a reactant which specifically binds to a target pathogen of interest, in combination with instructions for using said microparticles in a method of removing a pathogen of interest from a biological fluid sample. The HDM have a density within the range of 7-10 g/cm3 and may optionally be lyophilized to improve stability during storage. HDM could be packaged integral to a sterile disposable for processing the biological fluid. Formulations of HDM include liquid suspensions, or lyophilized or powdered HDM. Liquid formulations may be stored at a temperature between xe2x88x9215 to 15xc2x0 C., preferably at 2-8xc2x0 C., and most preferably can be stored at ambient temperature. Alternatively, the kit could comprise a separate container of HDM, such as a vial, with appropriate means for attaching to commercially available disposable fluid containment sets. Vials may be made of glass or polypropylene. Means of attachment include aseptic spiking and sterile connection using any number of commercially available systems.
As discussed above, it is often desirable to remove or separate the pathogens from a biological fluid sample. Such instructions may indicate that a plurality of HDM, attached to a suitable reactant, are to be mixed with the sample. The HDM, with the target pathogen(s) bound thereto, are then allowed to differentially settle by gravity and the remaining sample is removed. One such application of this kit is for therapeutic uses, where the fluid sample that has been purged of pathogens, is to be reinserted or transplanted into a living organism, such as the human body. In such a case, as well as in all applications described herein, it may be preferable to use HDM that have magnetic properties so that a magnetic field can be used after completion of the gravity settling step, to further insure that all the HDM are removed from the sample.
The general methods of the invention are best understood with reference to the following examples which are intended to enable those skilled in the art to understand more clearly and to practice the present invention. These examples are not intended, nor are they to be construed, as limiting the scope of the invention, but merely are illustrative and representative thereof.

Use of high density microparticles for removal of pathogens


A propellant gas is described for tools, operated by combustion power, especially for setting equipment for fastening elements, on the basis of combustible gases containing a mixture of (A) 40% to 70% by weight of dimethyl ether, nitrous oxide and/or nitromethane, (B) 8% to 20% by weight of propylene, methyl acetylene, propane and/or propadiene and (C) 20% to 45% by weight of isobutane and/or n-butane.

1. Field of Invention
The present invention relates to a propellant gas for tools, especially for setting tools for fastening elements operated by combustion power, based on combustible gases.
2. Description of the Prior Art
Tools of the type in question, operated by combustion power, namely setting tools for fastening elements, are disclosed in DE-A-4 032 202. With the help of these tools, fastening elements, such as nails, bolts, etc., are driven directly under the action of the combustion power, normally a powder charge, into materials such as wood, steel, concrete and the like, to which the component in question is to be fastened.
Such tools, operated by combustion power, comprise a combustion chamber and a piston, which can be moved in a piston guide and is acted upon by the expanding combustion gases produced in the combustion chamber. By igniting a mixture of air and fuel present within the combustion chamber or by igniting a powder propellant charge, the piston is moved away from the combustion chamber, strikes the fastening element and drives it into the constructional component. At the same time, the energy, gained by burning the propellant gas, depends very much on the combustion rate, which in turn depends on the ratio of air to gas.
Tools of this type, operated by combustion power, are also disclosed, for example, in DE-A-40 32 20 and U.S. Pat. No. 5,842,623.
The tool, which is operated by combustion power and described in U.S. Pat. No. 5,842,623, is operated by a mixture of methyl acetylene and propadiene or a mixture of propane, butane, propylene or ethane as propellant gas. For conventional, commercial tools of the type in question, which are operated by combustion power, especially mixtures of methyl acetylene, propadiene, propylene and butane are used, which are also known under the name of MAPP. This gas is a waste product of the coking of hard coal and has a relatively high combustion rate, which is important for a high efficiency of the tools.
However, these conventional propellant gases have considerable disadvantages. For example, the usually employed MAPP mixtures generally contain small amounts of butadiene, which is poisonous and permissible only in amounts of less than 0.1% by weight. MAPP gases, free of butadiene, are difficult to obtain and expensive. The usual hydrocarbon mixtures or pure fuel gases, such as butane or propane, burn more slowly and are unsuitable for the present application.
In particular, most of the known gas mixtures, used as propellant gases, evaporate slowly and weakly at low temperatures (xe2x88x925xc2x0 C.). This is a problem for the tools under discussion, since the latter must function at building sites even at temperatures below 0xc2x0C.
On the other hand, hydrocarbons, which burn rapidly, can be obtained only at high costs and frequently have vapor pressures, which are too high. This makes it difficult to adhere to the regulations of the authorities concerning the handling of aerosols.
Accordingly, the object of the present invention is a propellant gas for tools, operated by combustion power, especially for setting tools for fastening elements, which is not poisonous, can be procured simply and inexpensively, has the required combustion energy, makes a selective adjustment of this combustion energy possible, can be used even at low temperatures and makes it possible to comply with the aerosol regulations.
This and other objects of the present invention, which will become apparent herein after, are achieved by using a propellant gas in the form of a mixture of three components in a particular ratio by weight, these components, themselves possibly representing mixtures.
The inventive propellant gas is a mixture containing (A) 40% to 70% by weight of dimethyl ether, nitrous oxide and/or nitromethane, (B) 8% to 20% by weight of propylene, methyl acetylene, propane and/or propadiene and (C) 20% to 45% by weight of isobutane and/or n-butane, the sum of the components amounting to 100% by weight.
The components (A), (B) and (C) may contain one or more representatives of the combustible gases given.
Component (A) preferably is present in an amount of 50% to 60% by weight, component (B) in an amount of 10% to 15% by weight and component (C) in an amount of 25% to 35% of the gas mixture.
Preferably, the inventive propellant gas contains dimethyl ether as component (A), propylene as component (B) and isobutane as component (C). Pursuant to a particularly preferred embodiment, the inventive propellant gas comprises a mixture of 58% by weight of dimethyl ether, 14% by weight of propylene and 28% by weight of isobutane.
In addition, the inventive propellant gas may contain small amounts of other combustible gases, which are not poisonous and do not affect the vapor pressure and the combustion rate of the gas mixture disadvantageously.
The dimethyl ether, preferably used as component (A) pursuant to the invention, is known as a coolant and as a propellant for aerosol spray cans. Recently, the use of dimethyl ether as a fuel in the automobile industry has also been considered. In this connection, reference is made to U.S. Pat. No. 5,626,294.
With the help of component (A) and especially of the dimethyl ether, the use of which is preferred pursuant to the invention, it is possible to form a propellant gas, which makes possible the desired vaporization pressure even at low temperatures. Dimethyl ether has a relatively broad ignition window, that is, a large ratio of gas to air, in which the mixture is capable of igniting. Dimethyl ether is not classified as poisonous and, surprisingly, brings about a combustion rate greater than that of the MAPP mixture conventionally used. The molecule of dimethyl ether contains an oxygen atom, which leads to improved combustion, which means, percentage-wise, that less air has to be admixed when the inventive propellant gas is used than when pure hydrocarbons are used. This in turn makes smaller combustion chambers possible for the tools operated by combustion power and, with respect to the waste gases ejected, is advantageous. The vaporization pressure of dimethyl ether is not too high (5.1 bar (absolute) at 20xc2x0 C. and 11.7 bar at 50xc2x0 C.), so that it is suitable for use in aerosol cans. This makes it possible to use the inventive propellant gas in a compressed or liquefied form in a pressure container with a delivery valve.
The combustible gases, nitrous oxide and nitromethane, which can also be used as component (A), have physical and chemical properties, advantageous for the aimed-for use as propellant gas for tools operated by combustion power. Nitromethane can therefore be used alone or in mixtures with nitrous oxide and/or in combination with dimethyl ether in the claimed propellant gas. In this connection, the individual components are used in such amounts, that a vapor pressure results, which is suitable for the intended use.
Component (B) contains a reactive double bond in its molecule, which leads to improved combustion of the molecule and, with that, of the propellant gas mixture. The relatively high vaporization pressure of this component, namely of the preferably used propylene (10.2 bar at 20xc2x0 C. and 5 bar at 5xc2x0 C.), favors the atomization of the other components of the propellant gas through the nozzles when the propellant gas is introduced into the combustion chamber of the tool.
The component (C), namely isobutane, is used to stabilize the mixture. It is gaseous at temperatures above xe2x88x9211.5xc2x0 C. and therefore also permits advantageous combustion.
By combining dimethyl ether, nitrous oxide and/or nitromethane alone in combination with one another, with the other inventive components (B) and (C), a propellant gas mixture results, which is distinguished by a surprisingly advantageous, balanced combination of physical, chemical and environmental properties. The claimed propellant gas is distinguished on the basis of the combination of components (A), (B) and (C) by a behavior, which meets practical requirements particularly well during the manufacture and during the filling into containers, and especially also during the handling, in that the mixture readily fulfills the aerosol requirements and can be taken from the pressure containers with conventional metering valves without causing problems with the materials of the valves. Furthermore, the inventive propellant gas has an outstanding ignitability and combustion rate even at low temperatures (xe2x88x925xc2x0 C.), as a result of which the setting of fastening elements can be accomplished in a satisfactory and safe manner even under climatically unfavorable conditions.
The inventive propellant gas may additionally contain a lubricant based, for example, on mineral oil or silicone oil, for lubricating the valve devices, which are necessary for introducing the propellant gas into the combustion chamber.

Propellant gas for tools operated by combustion power


A neuromodulation system and method of providing therapy to a patient. Electrical energy is delivered to the patient in accordance with a modulation parameter, thereby providing therapy to the patient, and the modulation parameter of the delivered electrical energy is varied over a period of time, such that the delivered electrical energy is continually maintained at a sub-threshold level throughout the period of time. The sub-threshold level may be referred to as a patient-perception threshold, which may be referred to as a boundary below which a patient does not sense delivery of the electrical energy. For example, in a spinal cord modulation system, the patient-perception threshold may be a boundary below which a patient does not experience paresthesia.

Implantable neuromodulation systems have proven therapeutic in a wide variety of diseases and disorders. Pacemakers and Implantable Cardiac Defibrillators (ICDs) have proven highly effective in the treatment of a number of cardiac conditions (e.g., arrhythmias). Spinal Cord Stimulation (SCS) systems have long been accepted as a therapeutic modality for the treatment of chronic pain syndromes, and the application of tissue stimulation has begun to expand to additional applications such as angina pectoralis and incontinence. Deep Brain Stimulation (DBS) has also been applied therapeutically for well over a decade for the treatment of refractory chronic pain syndromes, and DBS has also recently been applied in additional areas such as movement disorders and epilepsy. Further, in recent investigations, Peripheral Nerve Stimulation (PNS) systems have demonstrated efficacy in the treatment of chronic pain syndromes and incontinence, and a number of additional applications are currently under investigation. Furthermore, Functional Electrical Stimulation (FES) systems, such as the Freehand system by NeuroControl (Cleveland, Ohio), have been applied to restore some functionality to paralyzed extremities in spinal cord injury patients.
These implantable neuromodulation systems typically include one or more electrode carrying stimulation leads, which are implanted at the desired stimulation site, and an implantable neuromodulation device (e.g., an implantable pulse generator (IPG)) implanted remotely from the stimulation site, but coupled either directly to the neuromodulation lead(s) or indirectly to the neuromodulation lead(s) via a lead extension. The neuromodulation system may further comprise a handheld external control device (e.g., a remote control (RC)) to remotely instruct the neuromodulator to generate electrical stimulation pulses in accordance with selected stimulation parameters.
Electrical modulation energy may be delivered from the neuromodulation device to the electrodes in the form of an electrical pulsed waveform. Thus, electrical energy may be controllably delivered to the electrodes to therapeutically modulate neural tissue. The configuration of electrodes used to deliver electrical pulses to the targeted tissue constitutes an electrode configuration, with the electrodes capable of being selectively programmed to act as anodes (positive), cathodes (negative), or left off (zero). In other words, an electrode configuration represents the polarity being positive, negative, or zero. Other parameters that may be controlled or varied include the amplitude, width, and rate of the electrical pulses (which may be considered electrical pulse parameters) provided through the electrode array. Each electrode configuration, along with the electrical pulse parameters, can be referred to as a "modulation parameter set."
With some neuromodulation systems, and in particular, those with independently controlled current or voltage sources, the distribution of the current to the electrodes (including the case of the neuromodulation device, which may act as an electrode) may be varied such that the current is supplied via numerous different electrode configurations. In different configurations, the electrodes may provide current or voltage in different relative percentages of positive and negative current or voltage to create different electrical current distributions (i.e., fractionalized electrode configurations).
As briefly discussed above, an external control device can be used to instruct the neuromodulation device to generate electrical pulses in accordance with the selected modulation parameters. Typically, the modulation parameters programmed into the neuromodulation device can be adjusted by manipulating controls on the handheld external control device to modify the electrical modulation energy provided by the neuromodulation device system to the patient. Thus, in accordance with the modulation parameters programmed by the external control device, electrical pulses can be delivered from the neuromodulation device to the electrode(s) to modulate a volume of tissue in accordance with a set of modulation parameters and provide the desired efficacious therapy to the patient. The best modulation set will typically be one that delivers modulation energy to the volume of tissue that must be modulated in order to provide the therapeutic benefit (e.g., treatment of pain), while minimizing the volume of non-target tissue that is modulated.
However, the number of electrodes available combined with the ability to generate a variety of complex electrical pulses, presents a huge selection of modulation parameter sets to the clinician or patient. For example, if the neuromodulation system to be programmed has an array of sixteen electrodes, millions of modulation parameter sets may be available for programming into the neuromodulation system. Today, neuromodulation systems may have up to thirty-two electrodes, thereby exponentially increasing the number of modulation parameters sets available for programming.
To facilitate such selection, the clinician generally programs the neuromodulation device through a computerized programming system. This programming system can be a self-contained hardware/software system, or can be defined predominantly by software running on a standard personal computer (PC). The PC or custom hardware may actively control the characteristics of the electrical stimulation generated by the neuromodulation device to allow the optimum stimulation parameters to be determined based on patient feedback or other means and to subsequently program the neuromodulation device with the optimum modulation parameter sets.
For example, in order to achieve an effective result from conventional SCS, the lead or leads must be placed in a location, such that the electrical modulation energy (in this case, electrical stimulation energy) creates a sensation known as paresthesia, which can be characterized as an alternative sensation that replaces the pain signals sensed by the patient. The paresthesia induced by the stimulation and perceived by the patient should be located in approximately the same place in the patient's body as the pain that is the target of treatment. If a lead is not correctly positioned, it is possible that the patient will receive little or no benefit from an implanted SCS system. Thus, correct lead placement can mean the difference between effective and ineffective pain therapy. When electrical leads are implanted within the patient, the computerized programming system, in the context of an operating room (OR) mapping procedure, may be used to instruct the neuromodulation device to apply electrical stimulation to test placement of the leads and/or electrodes, thereby assuring that the leads and/or electrodes are implanted in effective locations within the patient.
Once the leads are correctly positioned, a fitting procedure, which may be referred to as a navigation session, may be performed using the computerized programming system to program the external control device, and if applicable the neuromodulation device, with a set of modulation parameters that best addresses the painful site. Thus, the navigation session may be used to pinpoint volume of activation (VOA) or areas correlating to the pain. Such programming ability is particularly advantageous for targeting the tissue during implantation, or after implantation should the leads gradually or unexpectedly move that would otherwise relocate the stimulation energy away from the target site. By reprogramming the neuromodulation device (typically by independently varying the stimulation energy on the electrodes), the volume of activation (VOA) can often be moved back to the effective pain site without having to re-operate on the patient in order to reposition the lead and its electrode array. When adjusting the volume of activation (VOA) relative to the tissue, it is desirable to make small changes in the proportions of current, so that changes in the spatial recruitment of nerve fibers will be perceived by the patient as being smooth and continuous and to have incremental targeting capability.
Although alternative or artifactual sensations are usually tolerated relative to the sensation of pain, patients sometimes report these sensations to be uncomfortable, and therefore, they can be considered an adverse side-effect to neuromodulation therapy in some cases. Because the perception of paresthesia has been used as an indicator that the applied electrical energy is, in fact, alleviating the pain experienced by the patient, the amplitude of the applied electrical energy is generally adjusted to a level that causes the perception of paresthesia. It has been shown, however, that the delivery of sub-threshold electrical energy (e.g., high frequency pulsed electrical energy and/or low pulse width electrical energy) can be effective in providing neuromodulation therapy for chronic pain without causing paresthesia.
Although sub-threshold modulation therapies have shown good efficacy in early studies, because there is a lack of paresthesia that may otherwise indicate that the delivered sub-threshold electrical energy is optimized, or at least efficacious, it is difficult to immediately determine if the delivered sub-threshold therapy is optimized in terms of providing efficacious therapy. Thus, identifying an efficacious modulation parameter set for sub-threshold therapy may take several days, if not weeks, requiring several reprogramming sessions with the clinician.
There, thus, remains a need to provide a means to ensure that a patient is being effectively treated using electrical sub-threshold therapy.
In both conventional neuromodulation therapy described above where the patient feels paresthesia (super-threshold neuromodulation therapy) and sub-threshold neuromodulation therapy, common complications, caused due to cellular and synaptic mechanisms, include neurological phenomena, such as accommodation, adaption, and habituation, all of which entail a diminished neural response over time when there exists continuous input (in this case, electrical stimulation). For the purposes of this specification, we will use the term "accommodation" to generally refer to any mechanism that diminishes neural response due to continuous input.
Oftentimes, due to accommodation, a clinician may identify a modulation parameter set where a patient is obtaining great paresthesia, but when the clinician subsequently returns to this modulation parameter set, even within the same programming session, the patient may no longer receive the same paresthesia. While this complication may be tackled a little more easily in the case of super-threshold neuromodulation therapy, it is more difficult in the case of sub-threshold neuromodulation therapy because the clinician may not be able to determine, due to the lack of paresthesia, whether, and when, accommodation has occurred. Thus, without realizing that accommodation has occurred, the patient may continue receiving neuromodulation therapy but may receive little or no benefit from it.
There, thus, remains a need for an improved method and system that avoids or otherwise manages neurological accommodation caused by sub-threshold neuromodulation.

System and method for delivering modulated sub-threshold therapy to a patient

Boston Scientific Neuromodulation Corporation


The present invention is directed to a light monitoring system used in a water treatment system. The monitoring system includes a light pipe and a light intensity detector. The light pipe is impregenated with a florescent dye that converts ultraviolet light into visible light. The light pipe includes a plurality of internal facets that focus light incident on the light pipe toward the light intensity detector. The light intensity detector monitors the visible light transmitted to the detector by the light pipe and determines the relative ultraviolet light output intensity of a lamp assembly within the water treatment system based on the monitored visible light.

The present invention relates to point-of-use water treatment system (WTS) units used in homes and offices to filter and treat contaminants in water.
The present invention minimizes or overcomes several problems associated with previous point-of-use home or office water treatment system (WTS) units. A first problem is that conventional WTS units, utilizing lamp assemblies with UV bulb assemblies therein, are energy inefficient. When a conventional lamp assembly is turned on, it takes a significant amount of start-up time before gases within a UV bulb assembly are sufficiently excited to output light of an intensity level required to insure adequate destruction of microorganisms within the WTS unit. Water which is discharged from the WTS unit before a UV bulb assembly is sufficiently excited and microorganisms properly irradiated may carry an unacceptably high level of live microorganisms. Consequently, conventional lamp assemblies are left continuously running which uses a significant amount of energy. Also, with the lamp assembly left running continuously, such as overnight, water residing within a WTS unit can become uncomfortably warm. Finally, the life expectancy of a lamp assembly which is kept running continuously is significantly reduced relative to a lamp assembly which is only activated when water is to be treated.
A second problem is with the design of reflector assemblies within WTS units. In an attempt to increase lamp efficiency, reflector assemblies may be placed about UV bulb assemblies and water carrying conduits in which the microorganisms are irradiated. Light emitted from a UV bulb assembly which misses striking water carrying conduits is reflected back from the reflectors walls and has a chance to again impinge upon the water carrying conduits. These reflector assemblies may be circular in cross-section. Unfortunately, a lot of the UV light produced by these circular reflector designs never reaches the water carrying conduits. Rather, a significant portion of reflected light is reabsorbed by the UV bulb assembly and never reaches the water carrying conduit.
A third problem involves the electrical coupling of the lamp assemblies to WTS units. Every time a lamp assembly is installed in or removed from a WTS unit, the lamp assembly must be mechanically and electrically coupled and uncoupled relative to the WTS unit. This often required complicated and expensive electrical mounting assemblies. Further, care must be taken to insure that the electrical connections are not exposed to moisture while electrical power is passing through the WTS unit.
Coaxially aligned lamp assemblies and filter assemblies are sometime used to minimize the size of WTS units. A lamp assembly and filter assembly in a particular WTS may or may not be simultaneously removed from the WTS unit. If these assemblies are simultaneously removed, they are often very quite heavy as they may have substantial weight on their own and may be filled with water. Alternatively, even if the lamp and filter assemblies are separably removably from a WTS unit, quite often problems exist of water spilling from one of these assemblies during handling.
Another problem faced by WTS units having UV lamp assemblies is that complicated monitoring systems are needed to monitor the lamp assemblies. As a lamp assembly ages, the intensity of UV light output from the lamp assembly generally diminishes. Eventually, the intensity falls below a level necessary to effect a desired microorganism kill rate. The lamp assembly should be replaced before the desired minimum intensity is reached. Accordingly, a monitoring system is required to check on the UV light intensity within the WTS unit. These monitoring systems are typically expensive. They often require costly UV light sensors with quartz windows.
Point-of-use water treatment systems are typically left running continuously due to microorganism growth that would otherwise occur if the systems were shut down. Lamp assemblies in typical WTS units require a relative long time to reach a threshold value of emitted radiation intensity needed to attain a desired kill rate. Accordingly, water containing unacceptably high levels of live microorganisms may be delivered from a WTS unit before that threshold value of light intensity is reached.
Other problems and deficiencies that typical WTS units have include complicated assembly and locking mechanisms for mounting filter and lamp assemblies which may include nuts, bolts and O-rings which must be manually installed.
These and other deficiencies in prior WTS units employing lamp assemblies and filter assemblies are overcome by the present invention.
The present invention includes a point-of-use water treatment system which has a base unit, a filter assembly with an inner sleeve and a secondary water treatment device such as a UV lamp assembly. The inner sleeve provides a chamber for the secondary water treatment device. Ideally first and second valves and seals provide control of the flow of water between the filter assembly and the secondary water treatment device and between the secondary water treatment device and the base unit. The valves and seals prevent unwanted water spillage when the filter assembly and lamp assembly are removed and replaced from the base unit.
The present invention also includes a lamp assembly, preferably for use in a water treatment system that includes a bulb assembly, a reflector assembly and a conduit carrying water through the lamp assembly. The reflector assembly is configured or shaped to reflect and focus light emitted from the bulb assembly onto the conduit and away from returning to the bulb assembly thereby enhancing the efficiency of the lamp assembly.
The present invention further includes a replaceable lamp assembly, which includes a water-carrying conduit captured between a pair of ends caps and a bulb assembly for irradiating the conduit. The conduit serves as a reactor vessel in which microorganism and other contaminants may be treated. Enclosures may be used which cooperate with the end caps to form a generally closed vessel surrounding the UV bulb assembly and conduit. The lamp assembly may also include two or more conduits extending between the end caps. The lamp assembly is generally self-contained and can be readily installed in a test fixture or in the water treatment system.
Another aspect of the present invention is the use of condensing element to cool an intermediate portion of a bulb assembly between its filaments. The intermediate portion, which is cooled, allows a condensable material, such as mercury, to condense onto the intermediate portion of the bulb between filaments. When the lamp assembly is energized, the condensed mercury can quickly be revaporized as it lies in the arc path between the filaments. Otherwise, when the condensed mercury is located outside the arc path, the condensed mercury requires a greater time to become fully vaporized when the lamp assembly is reenergized. This condensing of the mercury in the arc path assists the lamp assembly in reaching a threshold intensity level in a shorter period of time. A condensing element extending between the bulb and a conduit carrying cool water can serve as a heat sink to cool the intermediate portion of the bulb in contact with the condensing element. If the condensing element is elastomeric, the condensing can also serve a cushioning functioning.
Yet another feature of the present invention is the use of a plastic light pipe impregnated with a florescent dye to convert UV light into visible light. This conversion allows the relative intensity of the UV light produced by a lamp assembly to be easily measured by an inexpensive visible light detector. The light pipe may include polished and angled surfaces to receive incident UV light and cause the light pipe to emit visible light at a particular emitting surface wherein the visible light may be measured for intensity. Preferably, the florescent dye is in the green wavelength of color.
An additional feature is the use of an inductively coupled base unit and lamp assembly to provide UV radiation necessary to kill microorganism passing through a water treatment system. Also, radio frequency identification (RFID) and communication between smart chips on the base unit, filter assembly and lamp assembly can provide information regarding operation of the water treatment system such as filter and lamp life and usage, identification of a particular filter assembly or lamp assembly, and other desired information. The use of inductive coupling and RFID allows the filter assembly and lamp assembly to operate without any hard wiring to a base unit. The base unit will include microprocessors to control the operation of the water treatment system.
It is an object of the present invention to provide a WTS unit which requires no direct physical electrical connection between a removable lamp assembly and a base unit which powers the lamp assembly.
It is another object to provide a WTS unit having a base unit with a primary coil and a lamp assembly with a secondary coil, the primary coil supplying energy to the secondary coil to power the lamp assembly such that a high intensity UV light is produced within the WTS unit.
A further object is to provide a reflector assembly in a WTS unit wherein the UV light produced by a UV bulb assembly is reflected and focused upon one or more conduits carrying water to be treated while minimizing reflected light striking and being absorbed by the UV bulb assembly.
It is an additional object to provide a WTS unit wherein a filter assembly cooperatively mounts to a base unit and to a lamp assembly to allow water to pass through the filter assembly and wherein when the filter assembly is removed from the base unit and lamp assembly, the filter assembly is self-sealing preventing water from spilling from the filter assembly.
Yet another object is to provide a WTS unit having a ballast and lamp assembly wherein a UV bulb assembly, upon start up, can virtually instantaneously produce UV light of sufficiently high intensity such that the lamp assembly can be run intermittently while maintaining desired microorganism kill rates.
Still yet another object is to provide a WTS unit which runs intermittently and has a UV bulb assembly with a pair of spaced apart filaments and a heat sink in contact with the UV bulb assembly such that a cool spot on the UV bulb assembly is formed between the filaments wherein at least one of the ionized gases will condense adjacent the cool spot between the filaments when the UV bulb assembly is deenergenized. This allows the condensed gas to be quickly reionized when the UV bulb assembly is reenergized.
Still yet another object is to provide a light pipe which receives UV light, fluoresces and outputs visible light generally linearly proportional in intensity to the incoming UV light.
An additional object is to provide smart chips in one or more of filter and lamp assemblies which transponds with an electrical assembly on a base unit to record usage information from the filter and lamp assemblies.

UV light intensity detector in a water treatment system