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  • 1
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 28 (1994), S. 1175-1186 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The composition of the protein layer adsorbed to a polymer has been thought to be important for the adhesion of platelets. The state of activation of adherent platelets is an additional factor that may be a predictor of biocompatibility. Activation refers to the degree of change from discoid shape to any of several spread shapes. The conformation and orientation of adsorbed adhesive proteins, which interact with receptors on the membrane of platelets, such as fibrinogen, fibronectin, and von Willebrand factor, may also be important for platelet adhesion and activation. This work deals with the behaviour of fibrinogen adsorbed to PMMA alone, where the experimental variable was incubation time with the substrate, and with adsorbed fibrinogen mixed with albumin, where the experimental variable was the molar percent of fibrinogen in the adsorption solution. Shorter protein incubation times and increased albumin levels in the initial fibrinogen adsorption solution enhanced the percentages of activated platelet morphologies and increased adsorbed fibrinogen redistribution by the platelet. Lower concentrations of albumin in the initial adsorption solution enhanced platelet adhesion numbers; fibrinogen incubation time had no effect. Together, these factors can contribute to the biocompatibility of a biomaterial through their effect on platelet adhesion and activation. © 1994 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
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  • 2
    ISSN: 0021-9304
    Keywords: cartilage ; growth factors ; tissue engineering ; osteogenic protein-1 ; cartilage repair ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The objective of this study was to examine in vitro the influence of recombinant human osteogenic protein-1 [rhOP-1, or bone morphogenetic protein-7 (BMP-7)] on cartilage formation by human and goat perichondrium tissue containing progenitor cells with chondrogenic potential. Fragments of outer ear perichondrium tissue were embedded in clotting autologous blood to which rhOP-1 had been added or not added (controls), and the resulting explant was cultured for 3 weeks without further addition of rhOP-1. Cartilage formation was monitored biochemically by measuring [35S]-sulphate incorporation into proteoglycans and histologically by monitoring the presence of metachromatic matrix with cells in nests. The presence of rhOP-1 in the explant at the beginning of culture stimulated [35S]-sulphate incorporation into proteoglycans in a dose-dependent manner after 3 weeks of culture. Maximal stimulation was reached at 40 μg/mL (human explants: +148%; goat explants: +116%). Histology revealed that explants treated with 20-200 μg/mL of rhOP-1, but not untreated control explants, contained areas of metachromatic-staining matrix with chondrocytes in cell nests. It was concluded that rhOP-1 stimulates differentiation of cartilage from perichondrium tissue. The direct actions of rhOP-1 on perichondrium cells in the stimulation of chondrocytic differentiation and production of cartilage matrix in vitro provides a cellular mechanism for the induction of cartilage formation by rhOP-1 in vivo. Thus rhOP-1 may promote early steps in the cascade of events leading to cartilage formation and could prove to be an interesting factor in the regeneration of cartilage in articular cartilage defects. © 1998 John Wiley & Sons, Inc. J Biomed Mater Res, 40, 614-620, 1998.
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  • 3
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 25 (1991), S. 277-280 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The results of these in vivo experiments show that bovine pericardium can undergo calcification without direct contact with tissue. It is clear that the direct interaction of cells with implanted samples both promotes and accelerates the process of calcification. Moreover, dietary calcium supplements, calcium chloride and vitamin D can intensify the rate and extent of this process.
    Additional Material: 1 Ill.
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  • 4
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The application of superselective endovascular occlusion in vascular radiology has broadened the scope of possible radical surgery of giant angiodysplasias by reducing considerably the risk of severe haemorrhage during the surgery. Occlusion was performed on 229 patients using spherical and cylindrical particles of porous poly(2-hydroxyethyl methacrylate). The treatment of a patient suffering from angiodysplasia of the pelvis is described as an example. The first day following endovascular occlusion a hypercoagulation reaction developed, with a decrease of both the level of fibrinolysis and of anticoagulant factors. This was mainly due to a decrease of the level of antithrombin III and activation of the factor XIII indicating a strong tendency of intravascular thrombosis. During the third day, the hypercoagulation reaction increased. However, on the fifteenth day, parameters of the haemostasis system were close to normal values. Only the activity of the factor XIII remained high suggesting the stabilization and the organization of fibrin clot in the embolized blood vessel territory. © 1993 John Wiley & Sons, Inc.
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  • 5
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A series of studies were performed using S35-labeled heparin to determine the amount and the permanancy of heparin grafted onto nonthrombogenic surfaces. The calculated thicknesses of the heparin layers (based on geometrical areas) ranged from 100 to 1500 A. It was shown that the surface having a 100-A layer of attached heparin was nonthrombogenic. The stability of the heparin attached to polypropylene, silicone rubber, hydrin rubber, and graphite-benzalkonium-heparin (GBH) surfaces in distilled water, isotonic saline, and human plasma was measured. The results showed that after exposure to water and saline, the first three surfaces retained most of the attached heparin (〉90%) in contrast to the GBH surface which retained only 31%. After contact with human plasma for 3 hr at 37°C, polypropylene retained 32% and GBH surfaces 19% of the heparin which was initially present. In another series of experiments, the adsorption of P32-labeled proteins onto unheparinized, quaternary ammonium, and heparinized surfaces was measured. The results indicated that the amounts of albumin, Hageman factor, thrombin, and γ-globulin adsorbed onto heparinized surfaces were equal to or greater than the amounts adsorbed onto unheparinized surfaces. The implications of this in terms of the nonthrombogenicity of the heparinized surfaces are discussed.
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  • 6
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 2 (1968), S. 131-143 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: During the period covered by this investigation, toxicological studies were carried out in hamsters and rabbits. The results of injections, subcutaneously and in the buccal pouch of hamsters, indicated that the silicones used were nontoxic, non-absorbable, and well encapsulated by connective tissue elements with moderate tissue reaction. Further studies of various combinations of roomtemperature vulcanizing silastics indicated similar reactions when injected submucosally in the alveolar ridges and palate of rabbits. The injected materials remained in situ in the injected submucosal area and became well encapsulated by the proliferation of connective tissue and collagenous fibers. There was no evidence of macrophages or foreign body giant-cells in and around the proliferating connective tissue capsule. There were no macroscopic or microscopic signs of tumor formation. The encapsulated masses did not elicit bone resorption when localized adjacent to bone tissue.
    Additional Material: 12 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 6 (1972), S. 405-441 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Porcelain inlays coupled by a silane treatment to composite resins which were used as cementing media and in turn retained by an undercut were evaluated as to their marginal integrity and retention against conventionally restored teeth. These included restorations in teeth with undercuts of resins, composites, and porcelain inlays cemented with zinc oxyphosphate cements.The evaluations were determined by isotope penetration during thermal cycling (180 cycles from 12 to 50°C), scanning electron microscopy of sectioned restorations, and mechanical pull tests.The results showed improved retentive qualities and markedly improved resistance to marginal penetration. Improved adaptation of the composite to the tooth surface was produced by the mechanical action of seating the porcelain inlay.
    Additional Material: 29 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 6 (1972), S. 15-24 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Heat vulcanized silicone elastomer (Silastic-Dow) has been in clinical use as a prosthetic replacement material for over a decade. When subjected to operating stress in body fluids, as in cardiac poppet-valves, failure has occurred. Fractures of silastic finger-joint prosthesis have also been experienced.Chemical and fractographic analyses of such failed finger-joint prostheses raise the suspiciaon of failure. Severe discoloration of the implant at the point of maximal stress concentration, the presence of significant amounts of triglyceride and cholesterol on the fractured prostheses, and the pattern of fracture markings indicate that fracture was due to a combination of chemical surface deterioration and stress concentration.Study of the method of surgical insertion of these prostheses suggests failure to completely excise the volar plate and other palmar joint structures could create a step off and sufficiently increase the stress in the bending element of the device to cause fracture. In vitro cyclic testing at 37°C in serum failed to cause fracture of these devices after 10 million cycles, but did produce gradual discoloration of the entire prosthesis which began and was most noticeable at the point of bending. Although the prostheses adsorb lipid, which may produce surface deterioration, it is anticipated that properly inserted, the service life of these devices should be more than adequate for full clinical application.
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  • 9
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 9 (1975), S. 453-463 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Dogs were dialyzed with collagen and cuprophane membranes, human renal failure patients were dialyzed with cuprophane membranes, and samples of the membranes were observed by scanning electron microscopy at different time periods. Fixation was done in glutaraldehyde and cacodylate buffer, and samples were dried at the critical point. All cellular elements were well preserved and appeared viable. Cuprophane adsorbed platelets almost selectively in dog dialyses, whereas collagen adsorbed a smaller number and more heterogeneous group of cells. In contrast to these findings, when cuprophane was used in clinical dialyses, the cell population was predominantly polymorphonuclear leukocytes.
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  • 10
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 9 (1975), S. 1-7 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Using rats as a model, porous discs of RPG carbon and polypropylene and polyethylene were localized subperiosteally and supraperiosteally in the skull. Bone and blood vessels grew into the discs, which had adequate pore size, when placed in direct contact with bone. No bone was generated from the periosteum. Both plastic materials were estimated to be better than carbon for use in osseous reconstructive work. More long term material-tissue stability and reaction studies should be performed.
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