Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L27/00—Materials for grafts or prostheses or for coating grafts or prostheses
  • A61L27/36—Materials for grafts or prostheses or for coating grafts or prostheses containing ingredients of undetermined constitution or reaction products thereof, e.g. transplant tissue, natural bone, extracellular matrix
  • A61L27/3604—Materials for grafts or prostheses or for coating grafts or prostheses containing ingredients of undetermined constitution or reaction products thereof, e.g. transplant tissue, natural bone, extracellular matrix characterised by the human or animal origin of the biological material, e.g. hair, fascia, fish scales, silk, shellac, pericardium, pleura, renal tissue, amniotic membrane, parenchymal tissue, fetal tissue, muscle tissue, fat tissue, enamel
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/02—Prostheses implantable into the body
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/02—Prostheses implantable into the body
  • A61F2/04—Hollow or tubular parts of organs, e.g. bladders, tracheae, bronchi or bile ducts
  • A61F2/06—Blood vessels
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L27/00—Materials for grafts or prostheses or for coating grafts or prostheses
  • A61L27/14—Macromolecular materials
  • A61L27/22—Polypeptides or derivatives thereof, e.g. degradation products
  • A61L27/227—Other specific proteins or polypeptides not covered by A61L27/222, A61L27/225 or A61L27/24
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L27/00—Materials for grafts or prostheses or for coating grafts or prostheses
  • A61L27/14—Macromolecular materials
  • A61L27/22—Polypeptides or derivatives thereof, e.g. degradation products
  • A61L27/24—Collagen
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L27/00—Materials for grafts or prostheses or for coating grafts or prostheses
  • A61L27/36—Materials for grafts or prostheses or for coating grafts or prostheses containing ingredients of undetermined constitution or reaction products thereof, e.g. transplant tissue, natural bone, extracellular matrix
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L31/00—Materials for other surgical articles, e.g. stents, stent-grafts, shunts, surgical drapes, guide wires, materials for adhesion prevention, occluding devices, surgical gloves, tissue fixation devices
  • A61L31/005—Ingredients of undetermined constitution or reaction products thereof
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L31/00—Materials for other surgical articles, e.g. stents, stent-grafts, shunts, surgical drapes, guide wires, materials for adhesion prevention, occluding devices, surgical gloves, tissue fixation devices
  • A61L31/04—Macromolecular materials
  • A61L31/043—Proteins; Polypeptides; Degradation products thereof
  • A61L31/044—Collagen
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L31/00—Materials for other surgical articles, e.g. stents, stent-grafts, shunts, surgical drapes, guide wires, materials for adhesion prevention, occluding devices, surgical gloves, tissue fixation devices
  • A61L31/04—Macromolecular materials
  • A61L31/043—Proteins; Polypeptides; Degradation products thereof
  • A61L31/047—Other specific proteins or polypeptides not covered by A61L31/044 - A61L31/046
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2310/00—Prostheses classified in A61F2/28 or A61F2/30 - A61F2/44 being constructed from or coated with a particular material
  • A61F2310/00005—The prosthesis being constructed from a particular material
  • A61F2310/00365—Proteins; Polypeptides; Degradation products thereof
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61L—METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES
  • A61L2430/00—Materials or treatment for tissue regeneration
  • A61L2430/32—Materials or treatment for tissue regeneration for nerve reconstruction

Definitions

• the present invention is directed to fetal membrane tubes for nerve and vessel grafts.
• Fetal membranes, amnion and chorion have been selected as our starting material for several reasons.
• the fetal membranes preferably are human although animal membranes can be used.
• Human placentas are available in relatively unlimited quantities and at low cost.
• amnion and chorion have been used for a wide variety of medical and surgical indications. (4) They have been shown to be capable of neovascularization.
• the fetal membranes are of a complex biochemical structure with unique physical characteristics. They can be modified physically by the processing technique later described herein into conduits which are semi-rigid, resilient, and of variable length, diameter and thickness.
• the biochemical components of the amnion and chorion membranes are mainly collagen types I, II , and III, laminin, fibronectin and other glycoproteins. Laminin has been shown to promote axon extension by interacting with axonal glycoproteins that are members of the integrin family of receptors.
• the immunocytochemical studies we conducted led us to modify our processing technique of the amnion and chorion membranes in order to preserve laminin as a significant component of these conduits, as later described herein.
• nerve autograft is the method employed to reconstruct a nerve gap.
• the disadvantages of nerve autografts are shown to be many, i.e. an additional surgical procedure is required, scarring with anesthesia or hyperesthesia at the donor site may be a problem, and there frequently are dimensional limitations of the donor grafts.
• nerve allografts have overcome several disadvantages of the autografts, rejection of the graft remains a major problem and limits its clinical use despite the use of immunosuppressive agents.
• the current interest and future directions in nerve research focus on the development of an ideal nerve conduit for clinical use.
• vascular conduits have been tried and in common use including preserved bovine vein grafts, dacron prosthetic grafts, teflon, and umbilical artery grafts. The high incidence of the thrombosis and infection of these graf is also a problem.
• t graft should be non-thro bogenic, easily accessible, o variable diameters and lengths, extensible, and flexible.
• Amniotic and chorionic collagen tubes or conduit according to the present invention are non-immunogenic and ca be constructed into tubes of variable lengths and diameter readily and easily.
• the amniotic and chorionic tubes of th present invention are well suited for use as nerve grafts o as bypass conduits for coronary bypass or vascular bypas surgery.
• the present invention is directed to providing nerv and vessel tubes or conduits for grafting to bridge gaps i nerves and vessels.
• I, II, III collagen derived from the amnion and chorio placentas in membrane form have been modified and the tube constructed so that they are maintained patent and flexible s blood flows through their lumen and their walls can withstan the interstitial pressure, and in which the fetal side o shiny side of the membrane is the inward side, which in th case of nerve grafts promotes axon growth.
• amnion and chorion is obtained from fresh placentas, preferably human, the amnion and chorion layers are separated from the placenta and each other, cellular monolayer material overlying the basal lamina on the fetal side of the membrane is removed, such as by exposure to trypsin or pepsin, the amnion and chorion is rinsed repeatedly with phosphate buffer solution or distilled water until clean, the amnion or chorion is then cross-linked either by exposure to gamma radiation or chemical cross-linking such as with glutar ldehyde, which sterilizes the tissue, provides protection against viral disease transmission, strengthens and permits remodeling the material from sheet to conduit form.
• glutar ldehyde which sterilizes the tissue, provides protection against viral disease transmission, strengthens and permits remodeling the material from sheet to conduit form.
• the amnion and chorion sheets are then wrapped in layers so that the fetal surface. which is shiny, is directed toward the inner surface of the finished tube.
• the number of wraps will depend upon the length and diameter of the tube.
• the tubes are then dried and placed in bottles which are sealed, labeled and, if desired, exposed to 2.5 M rads of gamma radiation to again sterilize and further cross-link the conduit collagen.
• the layers can be glued together by a suitable glue, such as a fibrin glue, to prevent delaminating, particularly in larger conduits, such as used for vascular grafts.
• the tubes or conduits can then be stored, for example at -20°C, until used.
• nerve promoting factors can be used within the amnion and chorion tubes at the time of implantation, for example particles of basal lamina, fibronectin, collagen extract, nerve growth factors and other related growth factors.
• It is a further object of the present invention to provide a graft for joining proximal and distal stumps of a severed peripheral nerve or proximal and distal ends of a vessel which comprises a cylindrical wall formed by layers of sheets of sterilized collagen, Types I, II, III, from human placenta from which its cellular material is substantially removed, which has its fetal side directed inwardly and its collagen cross-linked by irradiation or chemically, the cylinder having sufficient layers to maintain the cylinder patent or open, the cylinder having a length greater than the distance between the proximal and distal stumps or ends, and having a diameter at least equal to connecting tissues of the distal stumps or ends.
• a further object of the present invention is t provide such a graft in which the layers of amnion and/o chorion membranes are glued together effective to preven delamination of the layers. It is still a further object of the presen invention to provide such a cylindrical graft in which it wall permits flow of interstitial fluid through it to provid early nourishment for the graft, and in the case of nerv grafts, to provide nourishment for growth of Schwann cells. It is a still further object of the presen invention to provide such a cylindrical graft as a researc model for inclusion of material for medication study of nerv regeneration in the field of neurology.
• It is a further object of the present invention provide a nerve graft comprised of an amniotic and/o chorionic tube t containing related growth factors.
• amnion is obtained from fresh human placentas.
• the placentas are from hospital labor and delivery within 24 hours of parturition. Placentas obtained only from mothers who have been screened for AIDS and hepatitis virus and who are not members of the high risk groups such as IV drug abusers are used. Care is taken to avoid skin contact with blood and tissue and to minimize contamination of the work areas with these materials.
• the amnion layer is separated from the placenta, such as by finger dissection. The largest possible pieces of amnion which are of uniform thickness are selected from all the amnion harvested. The selected pieces of membrane are thoroughly washed, preferably with phosphate buffered saline, or distilled water to remove all the blood and debris. Then the membranes are further washed until they are white and transparent.
• the cellular onolayer overlying the basal lamina on the fetal side of the membrane is removed, such as by exposure to trypsin.
• Membranes are immersed for two hours at room temperature in 1:1 solution of distilled water and trypsin.
• the trypsin used preferably is from the procine pancreas at a 25% concentration without calcium or magnesium.
• the amnion is rinsed repeatedly, preferably with phosphate buffered saline, or with distilled water until clean, white membranes with no trace of pink trypsin are obtained.
• Rinsed amnion sheets are bottled in distilled water and exposed to 500,000 rads of gamma radiation. Irradiating the amnion cross-links the collagen, sterilizes the tissue, provides animal protection against viral disease transmission and subsequent remodeling of the material from sheet to conduit or tubular form. The bottles are then stored in a freezer at -8 °C. If desired, the amnion sheets may be cross- linked chemically such as with glutaraldehyde.
• Amnion is removed from frozen storage and then thawed for 3 to 4 hours at room temperature.
• the amnion sheets are examined under the operating microscope for defects and determination of the fetal or shiny side of the membrane.
• sheets of the amnion wide enough for a desired conduit length and diameter are carefully collected.
• the amnion sheets are oriented so that the fetal surface, which is shiny, would be directed towards the inner surface of the finished tube.
• wrapping of the amnion sheets in laye is effected by using a highly polished stainless steel ste of the appropriate diameter, although the amnion sheets can wrapped in any desired manner.
• conduits of 1.6-1.8 inches in diameter require approximately 10 wrap of amnion and 15 wraps are satisfactory for a diameter of 2.5
• the conduits can be of any desired length.
• the tubes whic are on the stents are then dried in 40-60°C oven for about 3 minutes. Drying allows the tubes to be removed from th stents easily.
• a suitabl adhesive or glue such as fibrin glue, can be used to glue th layers or wraps of amnion sheets together.
• the tubes are the placed in bottles which are sealed, labeled, and exposed t 2,000,000 rads of gamma radiation to again sterilize an further cross-link the conduits collagen. After that, th conduits are stored in -20°C until used.
• Example 1 the basement membrane integrity an lamina content of human amnion before, and after, th construction of the conduits were evaluated b immunocytochemical methods.
• Human amniotic conduit according to the invention have low immunogenicity which wa evidenced when different antigens in the amnion membrane, mainly collagen type 1, fibronectin, and laminin were tested by dot blot and ELISA techniques.
• amnion has been used for a wide variety of medical and surgical indications and has been shown to be capable of neovascularization. It has also been placed in subcutaneous pockets in human without evidence of acute rejection for as long as 7 weeks.
• the fetal membranes are of a complex biochemical structure with unique physical characteristics.
• the biochemical components of the amnion membrane are mainly collagen type I and type III, laminin, fibronectin and other glycoproteins.
• Laminin has been shown to promote axon extension by interacting with axonal glycoproteins that are members of the integrin family of receptors.
• the methods of processing the amnion membrane of the present invention preserve laminin as a significant component of these components.
• the present method of using gamma irradiation has several advantages. It has been shown that all bacteria, fungi, and viruses (including AIDS) are destroyed at .20 M rads.
• a dose of 2.5 M rad ⁇ is used in order to ensure complete sterility of the final material.
• This dose also increases amniotic collagen cross-linking which strengthens and thus enables the manufacture of the amniotic conduits in a semi-rigid form while retaining some resiliency to maintain patency after implantation.
• chemical cross-linking by known methods, such as exposure to glutaraldehyde, is effective and satisfactory.
• amniotic nerve conduit showed a minimal, nonsignificant immune response, thus, avoiding some of the inhibitory factors that could influence the regenerating nerve.
• amniotic conduits showed signs of biodegradability and structural reorganization grossly and by electron microscopic examination, local inflammatory cells infiltration was slight, being limited to the area surrounding the conduit wall, and it did not produce changes of chronic nerve compression. This latter development is a major problem encountered with the use of silicone rubber conduits for nerve regeneration recently presented for clinical use.
• the amniotic tube of t present invention can be used as a carrier for many materia that promote nerve regeneration, such as lamina, fibronecti collagen extract, nerve growth factors, and other relat factors.
• Collagen extract is collagen extracted from hum fetal membranes such as described in U.S. Patent N 5,002,071.
• basal lamina can be used as free dried ground, polarized, or preserved in any preservati solution within the amnion tube at the time of implantation
• Example 2 nerve regeneration through conduit according to the present invention was compare morphologically and functionally with autographs and othe • types of nerve tubes in an experimental animal model.
• Group 1 (3 animals) amnion tube.
• Group 2 (3 animals) amnion tube and basal lamina a a neurotrophic factor extracted form muscle.
• Group 3 (3 animals) nerve autograft.
• Group 4 (1 animal) sham operation as a control.
• the animals were followed for six months when the were harvested, and the nerve segments were studie morphologically and histologically.
• the cats were anesthetized using Demerol an phenobarbital intramuscular and a mixture of Halothane and No by inhalation.
• the tibial nerve was exposed, and a 4 c segment was excised and repaired as following:
• amnion an amnion tube was sutured t the distal and proximal stumps ensuring a gap of 4 cm. Two stitches were placed 180° apart on each side and went through -li ⁇ the whole thickness of the tube containing only the epineuriu of the nerve stump.
• group 2 amnion tube - basal lamina
• group 2 amnion tube - basal lamina
• a 4 cm segment of the nerve was excised, and the ga was bridged by an amniotic tube filled with basal lamina.
• amnion basal lamina as a strong candidate for nerve regeneration and show that the addition of muscle basal lamina to the amniotic collagen tube enhances nerve regeneration.
• axonal diameter histograms the amnion basal lamina group showed a distribution comparable to the sham with even larger axons and a considerable percentage of the axons (9%) fell in the range of from 1.5 to 2.25 microns.
• the histogram was comparable with the sham but with more percentage of axons (37%) falling in the range from 0.5 to 0.75 microns.
• the axonal diameters ranged between 0.1 to 1 micron with most of the axons (58%) falling in the range 0.25 to 0.5 microns.
• the axonal diameter histograms showed that basal lamina helped in rendering larger axons and provided to be the closest to the normal.
• Example 3 human chorion was substituted f human amnion.
• the chorion membrane was separated from t amnion membrane and was then harvested and treated the same in paragraph A, and conduits formed the same as in paragra B has properties similar to those set forth in Examples 1 a 2, and is satisfactory for both nerve growth and vascul tubes.
• the step of using trypsin or pepsin may be omitted the chorion is separated from the amnion.
• Example 4
• collagen Types I, II, and II, an combinations thereof derived from bovine amniotic an chorionic membranes were substituted for human membranes an prepared and formed into conduits or tubes as described abov and provide similar and satisfactory results for both nerv growth and vascular tubes as set forth above for the huma membranes.
• the methods of the invention comprise joining th proximal and distal stumps or ends of a severed nerve o proximal and distal ends of a vessel with a tube comprised o at least one layer of sterilized cross-linked membrane free o cellular or epithelial material comprising Types I, II, II collagen or mixtures thereof, laminin, fibronectin and othe glycoproteins, having its fetal side directed inwardly.
• Th membrane is sterilized and cross-linked by irradiation o chemically and has sufficient layers to maintain them paten in place.
• the tube has a length at least equal to th distance between the proximal and distal stumps or ends, an has a diameter at least equal and preferably slightly large than connective tissue of the proximal and distal stumps or ends.
• the tube can contain nerve growth factors, such as basal lamina, fibronectin or collagen extract or combinations of them, as previously mentioned.
• the tube is sutured or otherwise secured to the connective tissue adjacent the nerve stumps or vessel ends.
• the grafts are storable for extended periods of time providing a ready available source of graft material.
• the grafts can be formed of any required diameter and length, and the layers of the graft can be glued together to prevent delamination of the layers in use.
• grafts for bridging a gap between proximal and distal ends of a severed nerve or of a vessel comprising a cylinder having a wall formed of at least one layer of sterilized cross-linked membrane derived from Types I, II, III collagen or combinations thereof from placenta are suitable and satisfactory.

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• Health & Medical Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Animal Behavior & Ethology (AREA)
• Veterinary Medicine (AREA)
• Public Health (AREA)
• General Health & Medical Sciences (AREA)
• Chemical & Material Sciences (AREA)
• Epidemiology (AREA)
• Transplantation (AREA)
• Oral & Maxillofacial Surgery (AREA)
• Heart & Thoracic Surgery (AREA)
• Engineering & Computer Science (AREA)
• Biomedical Technology (AREA)
• Vascular Medicine (AREA)
• Dermatology (AREA)
• Medicinal Chemistry (AREA)
• Surgery (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Botany (AREA)
• Cardiology (AREA)
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• Urology & Nephrology (AREA)
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• Gastroenterology & Hepatology (AREA)
• Pulmonology (AREA)
• Prostheses (AREA)
• Materials For Medical Uses (AREA)
• Medicines Containing Material From Animals Or Micro-Organisms (AREA)
• Graft Or Block Polymers (AREA)

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• 1992
  • 1992-11-25 CA CA002124190A patent/CA2124190A1/en not_active Abandoned
  • 1992-11-25 WO PCT/US1992/010165 patent/WO1993010722A2/en not_active Application Discontinuation
  • 1992-11-25 RU RU94028108/14A patent/RU94028108A/ru unknown
  • 1992-11-25 AU AU32245/93A patent/AU663150B2/en not_active Ceased
  • 1992-11-25 EP EP19930900646 patent/EP0614345A4/de not_active Ceased
  • 1992-11-25 ZA ZA929119A patent/ZA929119B/xx unknown
  • 1992-11-25 JP JP5510233A patent/JPH07501465A/ja active Pending
  • 1992-11-26 NZ NZ245286A patent/NZ245286A/en unknown
  • 1992-11-26 CN CN92114817A patent/CN1079912A/zh active Pending
  • 1992-11-26 IL IL10389392A patent/IL103893A/xx not_active IP Right Cessation
  • 1992-12-15 TW TW081110056A patent/TW310273B/zh active
• 1994
  • 1994-05-24 NO NO941917A patent/NO941917D0/no unknown
  • 1994-05-25 FI FI942425A patent/FI942425A/fi not_active Application Discontinuation

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