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  • Articles  (636)
  • Polymer and Materials Science  (636)
  • 1985-1989  (636)
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  • 1
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 23 (1989), S. 223-239 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Attachment and growth of mouse fibroblast cells on polypeptide derivatives with different wettabilities were studied in the presence or absence of serum proteins. In the presence of serum, a peak level of cell attachment was observed for substrates with a contact angle of around 70°. However, no relationship was found between cell attachment and water contact angle of the substrate in the absence of serum. Ca2+-dependent cell attachment was observed on hydrophobic polypeptides in the absence of serum proteins. This suggests that Ca2+-dependent membrane proteins function as mediators for cell attachment to hydrophobic polypeptides. In the presence of serum proteins, it was found that cell attachment is affected by the metabolism, Ca2+, and the cytoskeleton of the cell. Cell growth rate on hydrophilic polypeptide substrates was higher than that on intermediate or hydrophobic polypeptide substrates. This demonstrates that the strong interaction between cells and substrates will be unfavorable for a dewebbing process during mitosis.
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  • 2
    Electronic Resource
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 23 (1989), S. 571-589 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: This study was performed to test the feasibility of using a biodegradable delivery system for the local controlled release of sodium fluoride as a mechanism for the stimulation of local bone growth. Sodium fluoride grains were mixed with poly-DL-lactic acid (PLA), and the mixture was then dissolved in acetone. After driving off the solvent, sheets of this material were rolled into rods 3.2 mm in diameter and 28.6 mm long. These were inserted into the intramedullary canals of the right femora of adult New Zealand White rabbits. A sham implant, made the same way but containing no fluoride, was inserted into the contralateral left leg. The effects of three different concentrations of sodium fluoride, 0.125 g NaF/g PLA, 0.250 g NaF/g PLA, and 0.500 g NaF/g PLA, were determined after a 4-week implantation period. In a second set of experiments, the concentration was fixed at 0.500 g NaF/g PLA with implantation durations of 4, 8, and 16 weeks. Expressed in terms of property ratios (experimental/control), bending strengths of the femora were significantly raised in most groups with the notable exception of Group 3 (0.500 g NaF/g PLA, 4 weeks). Cross-sectional area ratios in the distal femora were increased in all groups compared to right/left values for a normal unoperated group (p 〈 0.05), with the highest ratio being 1.50 (SD = 0.44) for Group 4 (0.500 g NaF/g PLA, 8 weeks). Only Group 4 animals showed significant (p 〈 0.05) increases in midshaft area ratio and none had responses proximally. Growth rates, measured by sequential fluorochrome labeling of bone followed the area ratio data and were only significant for the distal femora.
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  • 3
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 23 (1989), S. 649-660 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The organization of collagen in custombuilt biosynthetic vascular prostheses (Omniflow Vascular Graft), which are suitable for periphareral revascularization, has been examined. The grafts were a glutaraldehyde-tanned ovine-collagen composite with a polymer mesh reinforcement. Comparisons were made between grafts using different mesh fiber polymers and knit patterns. There was a basic similarity in the arrangement of the tissue structure in all graft types. Scanning electron microscopy and light microscopy showed that the collagen formed a layered structure which fully encased the polymer mesh and held it firmly in position. Rather than polymer mesh, the inner surface of the graft was found to be collagen, and lined with a layer of flattened cells. Collagen formed a continuous layer surrounding the mesh, with no distinct boundary membrane or structurally weak point being apparent. Immunohistology, using a monoclonal antibody specific for type III collagen, and chemical analysis, indicated that there was a high proportion of type III collagen in the grafts, particularly in the region surrounding the mesh fibers.
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  • 4
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
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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: Polyethylene terephthalate in textile form (Dacron®) has been used extensively as a surgical implant material for applications such as vascular grafts and percutaneous access devices. It is moderately histocompatible eliciting a chronic inflammatory reaction predominnately in tissue which has grown into the pores of the fabric. Titanium implants on the other hand, induce only the slightest inflammatory response and connective tissue adhesion to the titanium oxide surface is excellent. It was, therefore, hypothesized that a titanium coating on Dacron® fabric might improve its histocompatibility while leaving its desirable mechanical properties unaffected. To test this idea, Dacron® velour specimens were coated with titanium by vacuum deposition and were implanted together with uncoated controls in rabbits subcutis. After various implantation times, the specimens were recovered and the associated tissue was examined histologically. Qualitative and semiquantitative analysis revealed that tissue ingrowth quantity and quality was highly variable, not only between test and control specimens, but also between animals and even between specimens within the same animal. This indicated that there may be a number of factors influencing tissue ingrowth that were not adequately controlled in this study. The titanium coating which was undoubtedly highly oxidized had a profound qualitative and quantitative effect on fibroblast activity (ground substance formation) and fibroblast adhesion to the Dacron® fibers. The results obtained after these short-term implantation periods indicate that titanium coating affects the quality of the interfacing tissue and may actually improve long-term histocompatibility. Long-term studies will have to confirm these preliminary data.
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  • 6
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 23 (1989), S. 283-283 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
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  • 7
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Biodegradable beta-tricalcium phosphate disks (TCP) of two configurations were inserted into 15-mm-diameter craniotomy wounds and nontreated control sites were evaluated in 60 rabbits. There were no adverse tissue reactions and no apparent difference in the clinical appearance of the 12- and 24-week implanted disks. By 36 weeks and continuing to 48 weeks, the omnidirectional TCP (OTCP) implants were degrading more rapidly than the unidirectional TCP (UTCP) implants, with degradation progressing centripetally and replacement by woven bone and maturing lamellar bone. Host-implant interface of both TCP configurations was a bone bond without interposed soft tissue. TCP disks may be clinically useful for craniotomy repair.
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  • 8
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 23 (1989), S. 31-44 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The brain tissue reaction to permselective polymer capsules implanted in rats was evaluated for 1 to 54 weeks. The polymer capsules were well tolerated in all animals and no recognizable neurological or behavioral deficits were associated with the implants. Necrosis at the brain/polymer interface, as assessed with Nissl stain, was not observed. Foreign body giant cells were consistently absent. Immunocytochemically identified reactive neuroglial cells showed a remarkably low-grade tissue response to the synthetic material be yond the first 2 weeks of observation. Immunolabeled cortical neurons revealed conserved columnar arrays around the implants. Transmission electron microscopy showed a minimal degree of collagen deposition compared to implants in peripheral sites, and normal synapses within a few micrometers from the brain/polymer interface, supporting the prospect of biocompatible, immunoisolated xenografts in the central nervous system.
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  • 9
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 23 (1989), S. 105-123 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Understanding how platelet activation responses are affected by polymers having varied surface physicochemical properties can lead to improved materials for vascular applications. The in vitro responses of human platelets were studied upon adherence to four polyurethaneureas with different soft segments, as well as to Biomer, and to Formvar. Platelets were observed by video-enhanced light microscopy (VLM) as they adhered to polymer films. Platelets were subsequently prepared for high-voltage transmission electron microscopy (HVEM) to view the cytoskeleton and other ultrastructural features. Scanning electron microscopy (SEM) was then used to characterize cell surface morphology and to survey platelet populations. Shape change and cytoskeletal reorganization differed on the various surfaces. The extent of shape change and cytoskeletal reorganization was related to polyurethane surface energetic properties. While the most extensive shape change was observed on the hydrophilic and polar Formvar surface, the least shape change was observed on a polyethylene oxide soft segment polyurethane with similar surface-water energetic properties. Therefore properties other than surface-water energetics must be involved in determining platelet responses to different classes of polymers. HVEM also showed that cytoskeletal reorganization proceeded to completion only on Formvar. Polyurethane adherent platelets, although appearing fully spread by SEM or VLM, never exhibited complete cytoskeletal reorganization.
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  • 10
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 23 (1989) 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
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  • 11
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 23 (1989), S. 191-206 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Interactions of platelet with novel polyetherurethaneurea and its heparinized derivative were investigated. Platelet adhesion onto the material and release of serotonin or adenosine phosphate from platelet-rich plasma (PRP) were suppressed by an introduction of amino groups to polyetherurethaneurea, by quaternization of the polymer. When the material was precoated with one of major plasma proteins and the protein-coated materials were taken to contact with washed platelet suspension (WP), the dependence of platelet adhesion and activation on the properties of polymers was different from that observed for PRP interaction. Platelet adhesion and activation were promoted according to the nature of coating proteins in the order albumin 〈 γ-globulin 〈 fibrinogen and with increasing degree of denaturation of coating proteins. When the polymer materials were coated with proteins by immersing in aqueous solution containing two kinds of plasma proteins, adhesion behaviors of platelet were similar to those observed for PRP - uncoated material interaction. These experimental facts indicate that the selectivity of platelet for proteincoated material cannot be assessed by the interaction of WP with materials coated with a single kind of protein. It was concluded that material surface to which albumin is selectively adsorbed without denaturation does not stimulate adhering platelets for release reactions.
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  • 12
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 23 (1989), S. 241-252 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: At high frequencies, electrochemical impedance behavior for corroding dental amalgams cannot be interpreted in terms of a simple Randles equivalent circuit. This may often be ascribed to the imperfect cell geometry resulting in a nonuniform current distribution. However, the insertion of a constant phase element (CPE) in the nonfaradaic branch of the equivalent circuit offers a new scope for interpretation as the circuit provides an m-parameter corresponding to the degree of distortion. The decrease of m as a function of time was explained by a mathematical model reflecting an increasing number of pores. Moreover, that same model allows a better understanding of the passivating effect of NaHCO3 and of the differences between conventional and Cu-rich dental amalgams.
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  • 13
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 23 (1989) 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
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  • 14
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 23 (1989), S. 311-338 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: In order to investigate the factors affecting the interaction of polyurethanes and blood, a series of poly (tetramethylene oxide)-based polyurethane block copolymers was synthesized with systematically varying levels of ion incorporation in the hard segment block. A bimolecular nucleophilic substitution reaction was used to replace up to 20% of the urethane hydrogens with propyl sulfonate groups. Bulk and surface characterization was performed, and a canine ex vivo arteriovenous shunt was used to monitor initial platelet and fibrinogen deposition on these surfaces. The microphase separation and bulk physical properties were found to vary with ionic content. Surface analysis using both in vacuo (ESCA) and water-equilibrated (contact angle) methods indicated that these polymers, and especially the highly sulfonated materials, could rearrange to minimize their interfacial tension, depending on the contacting environment. Platelet deposition onto these materials decreased as the level of sulfonation increased, with the highly sulfonated polymer showing substantially less platelet spreading and activation than previously seen in the same experiment with other polymers.
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  • 15
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 23 (1989), S. 369-371 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 16
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 23 (1989), S. 373-373 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 17
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The fatigue properties of Simplex P and Palacos R bone cements were compared to their antibiotic impregnated counterparts AKZSupported in part by EM Laboratories, 5 Skyline Drive, Hawthorne, NY 10532; and The William H. Harris Foundation. and Palacos R with gentamycinAKZ bone cement is the trade name used by Howmedica Inc. of Rutherford, NJ to describe Simplex P mixed with 0.5 g of erythromycin and 0.24 g of colistin methane sulphonate Both the Simplex P and AKZ cements were obtained from Howmedica. Palacos R and Palacos R with gentamycin (0.5 g/40 g.) were supplied by E. Merck Laboratories. The effect of porosity reduction by centrifugation of all four cement types was also assessed. Fifteen specimens of each cement type were prepared according to manufacturer's instructions and 15 additional specimens of each cement type were prepared by mixing the powder with chilled monomer (0°C) and then centrifuging the cement immediately after mixing. Fifteen fully reversed tension-compression fatigue tests were performed at 15 MPa in stress control for each cement preparation in vitro while simulating the in vivo state (37°C and 100% humidity). The number of cycles to failure were recorded. There was no significant difference in the fatigue life of Palacos R and Simplex P when both cements were prepared in the standard fashion. The addition of 1/2 g of gentamycin to Palacos R did not significantly alter its fatigue properties. The addition of 0.5 g of erythromycin and 0.24 g of colistin did not decrease the fatigue life of Simplex P. Centrifugation significantly improved the fatigue properties of Simplex P and AKZ. The fatigue lives of Palacos R and Palacos R with gentamycin were not improved by centrifugation. The fatigue life of centrifuged Simplex P was significantly greater than the fatigue life of Palacos R and of Palacos R with gentamycin, whether the Palacos R based cements were centrifuged or not.
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  • 18
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 23 (1989), S. 457-475 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Tensile testing of tissue strips has been used to examine the effect of simple fixation in glutaraldehyde and formaldehyde on the viscoelastic properties of bovine pericardium. To assess tissue anisotropy, tissue strips were cut at 0°, 30°, 60°, and 90° relative to the base-to-apex direction. Fresh anterior pericardium was modestly anisotropic, being least extensible in the base-to-apex direction; however, fixation removed this anisotropy. Fixation also produced a marked change in the response of the material to initial cyclic loading during preconditioning. Overall extensibility of the fixed material was significantly greater than that for the fresh tissue, consistent with a 10.7% shrinkage in aldehydes calculated from strain at fracture data. Reductions in stress relaxation and creep after fixation were noted as well, consistent with intrafibrillar crosslinking. Cyclic hysteresis and ultimate tensile strength were unaffected. Since the observed changes in the stress-strain response were largely attributable to shrinkage, control of shrinkage by physical means would allow for engineering modification of bovine pericardial mechanics for controlled anisotropy.
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  • 19
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 23 (1989), S. 529-530 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
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  • 20
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    Journal of Biomedical Materials Research 23 (1989), S. 549-569 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The adsorption of bovine serum albumin from flowing solutions onto germanium and three polyetherurethanes varying in soft segment content was studied by a Fourier transform infrared/attenuated total reflectance technique. Spectral differences observed in the amide I, II, and III regions upon adsorption to all four surfaces were consistent with a loss of helix and gain of β-structure. There appeared to be a slight difference between BSA adsorbed to germanium and the PEUs, but no distinction could be made between BSA adsorbed to the different PEUs.
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  • 21
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 23 (1989), S. 611-630 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A covalently bonded conjugate of commercial grade heparin and prostaglandin E1 (PGE1) was synthesized to prevent both fibrin formation and platelet aggregation during thrombus formation. The PGE1-heparin conjugate was immobilized on an imidazole carbamate derivatized sepharose bead surface through hydrophilic spacer groups (diamino-terminated polyethylene oxides). One end of the spacer group was coupled to the derivatized surface through a urethane bond between the amine group of the spacer and the derivatized surface. The free amine group of the immobilized spacers was coupled to a carboxylic group of the PGE1-heparin conjugate through an amide bond. Bioactivity of the immobilized conjugate (heparin activity) was measured in terms of increased clotting times (thrombin time assay) and for the inactivation of Factor Xa. Bioactivity of the immobilized compound (PGE1 activity) was analyzed by platelet adhesion and platelet release reactions using C14-5-hydroxytryptamine (5-HT). The conjugate immobilized via the C2 spacer showed the highest incidence of platelet adhesion, 5-HT released and the lowest activity for coagulation factors. In contrast, the 1000 and 4000 immobilized systems showed a significant reduction in platelet activation, while having the greatest effect on coagulation factors. The results of these experiments imply that the immobilized conjugate is active in preventing both pathways of thrombus formation, and the efficacy is improved thorugh the use of long-chain hydrophilic spacer groups.
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  • 22
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    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 23 (1989), S. 671-673 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 23
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    Journal of Biomedical Materials Research 23 (1989), S. 719-733 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The influence of type and quantity of five different crosslinking agents on tensile creep properties of multiphase acrylic systems has been studied. The polymeric materials, commonly applied in bioengineering, were processed by polymerization of a mixture of liquid methacrylate monomers and poly(methyl methacrylate) powder. The specimens were made with various ratios of methyl methacrylate and crosslinking agents in the monomer liquid. Two different processing conditions were used, i.e., heat-polymerization at 100°C and autopolymerization at 45°C. Creep behavior was determined at 37 ± 0.2°C and 50 ± 0.5°C. The investigation showed higher creep values for autopolymerized than for heat-polymerized materials. In heat-polymerized materials the creep curves showed little variation with type and quantity of crosslinking agents at low stress levels. However, at high stress levels the creep values decreased with increasing quantity of crosslinking agents. The autopolymerized materials showed a more inhomogeneous structure, and great variation in creep. Both among the heat-polymerized and autopolymerized materials, the systems with diethyleneglycol dimethacrylate clearly deviated from the others by showing higher creep values.
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  • 24
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The adhesive properties of a series of oligomers prepared from 2-isocyanatoethyl methacrylates (IEM) and/or m-iso-propenyl-α,α-dimethylbenzyl isocyanate (TMI) and various acrylates or methacrylates were studied. The bond strength of bone, dentin, or soft tissue specimens joined with these oligomers respectively to bone, dental composite restorative, or denture base resin were determined by tensile adhesion or shear tests. These oligomers are more effective in forming stronger bonds to bone than are other tissue adhesives. Fracture occurs cohesively, usually within the bone. Thermocycling in water for 1 week between 5°C and 55°C did not decrease adhesion indicating that exposure to water or thermal shock produced no deterioration of the bond. Tensile adhesion of bovine or human dentin joined to composite restorative resin by means of the oligomers is similar to that of the best dental bonding agents such as Gluma (glutaraldehyde and 2-hydroxyethyl methacrylate) or ferric oxalate + Nphenylglycine + dimethylacryloxyethyl-pyromellitate. These oligomers also strongly bond soft tissues and calfskin and to acrylic resins and composites.
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  • 25
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    Journal of Biomedical Materials Research 23 (1989), S. 819-831 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: This study was conducted to investigate some fundamental fatigue testing variables as they apply to the response characteristics of acrylic bone cement. Cyclic loading under load control was conducted at frequencies of 1, 2, 5, 10, and 20 Hz in air at room temperature. At a tensile stress range of 0.3-20.0 MPa the fatigue life increased linearly with logarithmic frequency. The effect of conditioning and testing in saline at both room temperature and 37°C at similar stress levels and a frequency of 10 Hz were also examined. When compared to dry testing at room temperature, testing in saline at 37°C resulted in a reduction in fatigue life while testing in saline at room temperature produced an increase in fatigue life. Of a number of statistical distributions considered, the Weibull was found to be the most appropriate in documenting the findings of this investigation. A companion fractographic investigation of the failure surfaces demonstrated distinct regions of crack growth and fast fracture.
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  • 26
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    Journal of Biomedical Materials Research 23 (1989), S. 845-862 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A study was conducted to determine the ability of hamsters to eliminate in the urine, or store in the organs, large quantities of metal salts given over a period of several months. In addition, the effect of prior immunization on metal ion clearance was determined. The results indicated that nickel was rapidly eliminated in the urine and that the level in the organs was similar to that of control animals. Cobalt was eliminated more slowly than was nickel. The organ levels of cobalt were similar to those of control animals with a slight elevation in the liver of the injected animals. Chromium was eliminated in the urine very slowly, was red cell associated, and the levels were elevated in all the organs (liver, lung, spleen, kidney) compared to control. Prior immunization with metal salts increased the storage of chromium.
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  • 27
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    Journal of Biomedical Materials Research 23 (1989), S. 895-909 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Identically prepared, screw-type ceramic and titanium endosteal dental implants were inserted in the jaws of adult mongrel dogs for periods of up to 6 months. Sixteen of the 32 total implants supported fixed bridgework. The interface of bone and soft connective tissues with the dental implants was examined by routine and innovative scanning electron microscopic (SEM) techniques using both secondary and backscattered electron imaging. Results demonstrated excellent bone adaptation to both titanium and ceramic implants. Direct adaptation of bone to the upper third of both type implants was observed with only minimal amounts of any intervening fibrous connective tissue. A composite of trabecular bone and fibrous connective tissue was observed in the lower two-thirds of the implants examined. Areas of bone alteration suggestive of osteoid were observed at the thread apicis of some loaded implants. From this investigation we concluded that similar longitudinal tissue responses were generated to one-piece, cylindrical screw-type titanium and alpha alumina oxide ceramic dental implants. Possible bone remodeling was observed at the thread apicis of the loaded implants, an area where occlusal forces may be distributed. We further suggest that one-stage endosteal implants are capable of maintaining a proportional bone-to-implant interface at the apical support region, similar to that suggested to two-stage implant systems.
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  • 28
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    Journal of Biomedical Materials Research 23 (1989), S. 947-951 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: There are no differences in the multinucleate cell formation in normal and athymic mice after the subcutaneous implantation of a cellophane strip. The number of Ia+ epitheloid cells and multinucleate foreign body giant cells was lower and the number of epitheloid cells sharing the marker of activated macrophages (M 57) was higher in athymic compared to normal mice. The epitheloid cells of athymic and euthymic animals exhibited no difference in the expression of Mac-2 molecule. The difference of the expression of surface markers between athymic and euthymic animals does not influence the foreign body giant cell formation.
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    Journal of Biomedical Materials Research 23 (1989) 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 30
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    Journal of Biomedical Materials Research 23 (1989), S. 1027-1047 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The surface reactivity of the dog heartworm (D. immitis) was evaluated by comprehensive contact angle measurements and a platelet retention test. Contact angle data yielded calculated surface energy terms very similar to those previously reported for intact vascular endothelium. The platelet test revealed the native worm surface to be nonreactive, retaining fewer platelets than glass or worms whose surfaces had been modified by extraction with acid and high salt solutions. The cuticular morphology of the heartworm was studied with both light and electron microscopy, the latter coupled with ferritin-conjugated double-layer immunolabeling to reveal adsorbed host protein on the cuticle surfaces. Multiple attenuated internal reflection (MAIR) IR spectroscopy confirmed the general composition of this surface layer to be glycoproteinaceous. Morphological and histochemical studies confirmed and extended previous descriptions of nematode cuticle, adding ultrastructural detail on cortical, medial, and basal layers. A trilaminar membrane, apparently corresponding to a mammalian cell membrane (plasmalemma), constituted the external cortical layer as observed in high magnifications. The existence of a glycocalyx of varying thickness was demonstrated in ruthenium red-stained sections. MAIR IR spectra showed this glycoproteinaceous film to appear, in fully hydrated samples, as a loose biological gel. Ferritin-antibody conjugate labeling confirmed the presence of adsorbed dog albumin, dog immunoglobulin class G (IgG) and dog complement fraction 3 (C3) in the cuticular surface layer. It is likely, therefore, that D. immitis heartworms demonstrate long-term thromboresistance at least in part due to their passive low-surface-energy overcoating with host proteins.
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  • 31
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The cytotoxicity of hydroxyapatite (HA), tricalcium phosphate (TCP), and two types of phosphate (TCP), and two types of apatite-containing glass-ceramics designated A · W-GC and A · W · CP-GC was evaluated by the direct contact method using V79 cells. Compatibility of the cells was assessed as a function of cellular attachment and subsequent growth using scanning electron microscopy. Although all of the tested materials have surfaces available for cellular attachment, cell growth was markedly inhibited by HA sintered at 600°C and 900°C, and slightly inhibited by HA sintered at 1200°C, TCP and the glass-ceramics. In attempts to clarify the cause of this toxicity, the interactions of the ceramics with culture medium was assessed by measurement of calcium (Ca), inorganic phosphate (P), magnesium (Mg), pH and albumin content in the medium. The grade of toxicity corresponded to the degree of reduction of Ca, P, and albumin in the medium. Furthermore, surface reactions of the ceramics were demonstrated to vary in both mode and degree depending on their chemical structure and level of microporosity. Thus, the surface reactivity of ceramic materials should be always taken into account in discussing their biocompatibility in vivo.
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  • 32
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: Collagen fibers composed of type I collagen molecules were studied for biocompatibility and mechanical properties. These fibers were crosslinked using two different processes: (1) glutaraldehyde, (2) dehydration followed by exposure to cyanamide (DHT/C); the latter method produces only urea as a by-product of the crosslinking process and is postulated to be more biocompatible. An in vitro model using rat tendon fibroblasts growing on individual fibers was used to evaluate outgrowth rates, cell/fiber interactions, and cell morphology. These studies showed an advantage with DHT/C crosslinking, relative to glutaraldehyde crosslinking, in promoting fibroblast growth. In vivo intramuscular implantation in rats showed excellent biocompatibility for both kinds of collagen implants. In addition, aligned ingrowth into the implant from the medial collateral ligament when applied in that location was demonstrated. Mechanical testing demonstrated the higher strength of dry fibers; however, upon hydration, there was a marked decrease in stress to failure. This reduction in strength was due principally to an increase in cross section due to swelling. These collagen fibers appear to be very biocompatible even in the presence of low concentrations of glutaraldehyde. They promote fibrous aligned ingrowth in a setting of ligament healing. Thus, they represent a strong candidate as a scaffold ligament or tendon prosthesis if crosslink density can be increased.
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  • 33
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    Journal of Biomedical Materials Research 23 (1989), S. 1067-1085 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The effects of a grooved titanium-coated substratum on epithelial (E) cell behavior were studied in vitro and in vivo. V-shaped grooves, 10 m̈m deep, were produced in silicon wafers by micromachining, a process which was developed for the fabrication of microelectornic components. The grooved substrata were replicated in epoxy resin and coated with 50 nm of titanium. More E cells were found attached to the grooved titanium surfaces than to adjacent smooth surfaces. In comparison to the smooth surfaces where clusters of E cells were randomly oriented, on the grooved surfaces, clusters of E cells were markedly oriented along the long axis of grooves. Grooved and smooth titanium-coated epoxy implants were placed percutaneously in the parietal area of rats. Electron and light microscopic obsrvations indicated that E cells were tightly attached to the implant surfaces and this attachment is through basal lamina-like and hemidesmosome-like structures. In the grooved portion of the implant, E cells interdigitated into the grooves and had rounded nuclei. Histomorphometric measurements indicated that there was a shorter length of epithelial attachment, longer length of connective tissue attachment, and less recession in the grooved, compared to the smooth portion of implants after 7 and 10 days. These results indicate that horizontal grooves produced by micro-machining can significantly impede epithelial downgrowth on titanium-coated epoxy implants.
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  • 34
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    Journal of Biomedical Materials Research 23 (1989), S. 1097-1100 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 35
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    Journal of Biomedical Materials Research 23 (1989), S. 979-1005 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Hydrophilic-hydrophobic multiblock copolymers synthesized from telechelic oligomers of poly(ethylene oxide) (PEO) and polystyrene (PS) have been used to study the influence of hydrophilic and hydrophobic balance on interfacial interactions of these surfaces with blood components. In vitro coagulation assays show no inherent ability of these amphiphilic surfaces to affect contact activation or coagulation factors. In vitro platelet adhesion and release reactions from rabbit platelet-rich plasma were shown to be greatest on Biomer and PS homopolymer surfaces and least on cross-linked PEO surfaces, with the PEO-PS block copolymers demonstrating intermediate responses. These same substrates were tested in a new low-flow, low-shear arterio-artery shunt system in rabbits. Whole blood occlusion times were not a direct function of hydrophilic content as both PEO and PS homopolymers and Biomer showed short occlusion times, while PEO-PS block copolymers prolonged occlusion times considerably, depending on composition. Overall, results suggest that PEO-PS block copolymers promote unique whole blood responses in contrast to homopolymer and Biomer controls which are more complex than direct correlations to bulk hydrophilic and hydrophobic contents.
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  • 36
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    Journal of Biomedical Materials Research 23 (1989), S. 1007-1026 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Of the many factors determining host biocompatibility responses to implanted biomedical polymers, the cellular interactions at the tissue/material interface have been recognized to be some of the most important. The present study has combined results both from an in vitro cell culture system and from an in vivo animal model to examine this host response. In vitro results suggest that a variety of polymer materials can differentially activate human monocytes to produce a protein(s) having different biological activites. The polymers tested induce the production of the regulatory inflammatory protein interleukin 1 as well as a factor that enhances fibroblast proliferation and collagen synthesis. The observed activities of these factors appear to be related but not identical, and are dependent upon the specific polymer. Evaluation of exudate and tissue responses to these same polymer materials in an in vivo model are also presented. Both in vitro and in vivo results support the hypothesis that monocyte/macrophage activation with subsequent synthesis of regulatory factors such as interleukin 1 plays a significant role in determining the host response to biomedical polymer implants.
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    Journal of Biomedical Materials Research 23 (1989), S. 1087-1095 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The austenitic stainless steels used today for the manufacture of osteosynthesis devices are sensitive to crvice corrosion. In this study the corrosion properties of some duplex stainless steels were evaluated and compared to traditional austenitic stainless steels. According to our results the following ranking was established: 23Cr—4Ni 〈 AISI 316L 〈 ASTM F138 〈 22Cr—5Ni—3Mo 〈 27Cr—31Ni—3.5Mo 〈 25Cr—7Ni—4Mo—N. In particular the results showed that the high-performance 25Cr—7Ni—4Mo—N duplex stainless steel, with high molybdenum and nitrogen contents, can be considered not susceptible to crevice corrosion in the human body. The duplex stainless steels have also better mechanical properties at the same degree of cold working compared with austenitic stainless steels. Hence the 25Cr—7Ni—4Mo—N duplex stainless steel can be considered a convenient substitute of ASTM F138 for orthopedic and osteosynthesis devices.
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    Journal of Biomedical Materials Research 23 (1989) 
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    Keywords: Chemistry ; Polymer and Materials Science
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  • 39
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    Journal of Biomedical Materials Research 23 (1989), S. 1149-1168 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A new composite implant material titanium/glass-ceramic was tested in rabbits using light microscopy, histomorphometry, and biomechanical testing methods. Two rabbit implant models were used. The first premolar tooth was replaced and cylinders inserted into the trabecular bone of the distal femur below the patella sliding plane. There was bone bonding to the glassceramic component and additional mechanical interlocking, due to bone ingrowth between the titanium matrix into secondary pores. This was proved by measuring the tensile strength at the interface of the new composite material which was in the same range as compared to pure glassceramic implants. In tooth replacement there was a tight attachment of gingival epithelium and stroma to composite titanium/glass-ceramic. These results are of particular clinical interest: physicochemical bone bonding and additional mechanical interlocking result in a resistance of the implant material against shear and tensile loads at the interface. Therefore this new composite material should be suitable for further load-bearing applications.
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  • 40
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    Notes: Human adult aortic endothelial cell attachment to polyethyleneterephthalate (PET as mylar film) was examined in vitro. PET was examined in both the unmodified form (PET -) and in a modified form (PET +) that had undergone plasma discharge surface modification (PDSM). These surfaces were compared to unmodified tissue culture polystyrene (PS -). The kinetics of attachment and the force of attachment using the rotating disc were determined as a function of surface and substrate protein applied to the surface. Four proteins - fibronectin, collagen I/III, collagen IV/V, and laminin - were added and compared to saline pretreatment. The most significant variable affecting attachment was the time of incubation. When corrected for time, PET + demonstrated significantly superior attachment kinetics when compared to PET - in most cases. These kinetics were similar to those seen on PS-. Fibronectin precoating of the surface greatly enhanced attachment kinetics on PET + and PS- but to a much lesser degree on PET-. The fibronectin effect was synergistic with PDSM, suggesting that PDSM enhances protein adsorption on the surface. The force of attachment was generally independent of incubation time and surface/substrate combination except for laminin precoating. Taken together, these data indicate that human endothelial cell adherence to PET may be significantly enhanced by PDSM and surface precoating with fibronectin. Attachment occurs rapidly and, once attached, the cells demonstrate a very firm attachment force capable of resisting shear stresses up to 90 dynes/cm2.
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  • 41
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    Journal of Biomedical Materials Research 23 (1989), S. 1115-1130 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: In order to study the effects of factors governing the bioabsorption rate of polylactides, implantation tests were carried out in rabbits using various samples (20 × 10 × 2 mm3) differing in their chemical composition, residual monomer content, and molecular orientation. Copolymer samples with a higher lactic acid content showed a lower rate of absorption, whereas those with a higher unreacted monomer content were absorbed faster and showed a more drastic decrease in molecular weight. In contrast, degradation of the purified polymers was slow; the purified poly-L-lactide showed no weight change and a 50% reduction in molecular weight after 6 months of implantation. Scanning electron microscopy of the samples containing monomers showed a microporous structure extending from the surface to the inner region a few days after implantation, whereas the purified poly-L-lactide did not exhibit a microporous structural change even after 10 months of implantation.
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  • 42
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    Journal of Biomedical Materials Research 23 (1989), S. 1169-1182 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: In order to bring quantitative elements into the rational selection of animal species for the evaluation of in vivo compatibility of biomaterials, a comparison between the muscular tissue response of rats and rabbits was made using quantitative histomorphometry. The experimental model was based on the quantification of the tissue reaction to specimens made of ultra-high-density-polyethylene (UHDPE) implanted in the paravertebral muscles, according to ASTM F-469 standard. The tissue reaction was evaluated by digitization of both the encapsulating membrane contours and the different cells types located within it. In each animal species, the cell distribution from the interface exhibited an asymetric bell-shape curve with a maximum close to the interface, corresponding to a three-parameter statistical model. The membrane thikness, a fibrocyte-related parameter, was larger in the rabbit, but its time-course was identical in each species, showing a late and significant increase. Few differences were observed for most cell types due to the low level of foreign-body-reaction induced by HDPE implants. Although there were interspecies differences for fibrocytes and, to a lesser extent, macrophages, between 2 and 8 weeks, weeks, there was no statistical differences for any of the computed parameters either at 2 weeks or between 26-week rats and 52-week rabbits. The quantitative histomorphometry picked up differences between close tissue responses, whereas the qualitative observation was unable to demonstrate distinguishing differences between rats and rabbits.
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  • 43
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    Journal of Biomedical Materials Research 23 (1989), S. 1183-1193 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A correlation is established between the mesh size of a swollen cross-linked network and its equilibrium polymer volume fraction, for hydrogels isothermally swollen up to semidilute, dilute, or concentrated conditions. The exponent of this correlation decreases as the water concentration of the hydrogel decreases. Experimental results with hydrogels of poly(vinyl alcohol) and poly(2-hydroxy ethyl methacrylate) are used to verify the new scaling laws.
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  • 44
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: The biocompatibility of three commercial copper-based dental casting alloys - Duracast MS, Goldent, and Trindium - three experimental copper alloys, and a control gold alloy, Modulay, were investigated. Trindium, Duracast MS, experimental alloys 1 and 2 are aluminum bronzes; Goldent is a hybrid aluminum-brass alloy; and experimental alloy #3 is a high zinc brass alloy. ASTM F813-83 Standard Practice for Direct Contact Cell Culture Evaluation of Materials for Medical Devices, a 3-day direct-contact cell culture regimen and atomic absorption spectroscopy were utilized for evaluating the biocompatibility of these alloys in both Waymouth's and RPMI 1640 complete media. Cellular proliferation assays, using 3H-thymidine uptake, were also conducted in Waymouth's media. In this investigation, only the experimental alloy #3 elicited alterations in morphology and viability of the fibroblast monolayer during the ASTM and 3-day culture tests in either media. Cell cultures exposed to experimental alloy #3 experienced copper concentrations greater than 16.0 ppm in Waymouth's and 10 ppm copper in RPMI 1640 media. Differences in the size of the cytotoxic zone around experimental alloy #3 were also observed, with the larger zone occurring in Waymouth's media. In contrast to the direct cell contact studies, all alloys caused decreases in 3H-thymidine uptake in Waymouth's media at much reduced metal ion concentrations as compared to the controls. Thus, adverse changes in DNA synthesis occurred at much lower copper and zinc concentrations than changes in morphology and viability. Consequently, the assessment of biocompatibility is dependent on the parameters evaluated, and several parameters must be analyzed before a material may be considered biocompatible.
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    Journal of Biomedical Materials Research 23 (1989), S. 1231-1237 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Journal of Biomedical Materials Research 23 (1989), S. 1213-1229 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The histologic reaction to topically applied or intramucosally injected DPPC/chol (2:1 molar ratio) liposomes was investigated. No reaction to liposomes was observed 4 days after daily topical application. However, a mild focal immune type inflammatory reaction was observed after 21 days topical treatment. Intramucosal injection of liposome produced no irritation but a macrophage reaction limited to the injection site, which was followed by healing and complete tissue regeneration.
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    Journal of Biomedical Materials Research 23 (1989), S. 1243-1245 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Journal of Biomedical Materials Research 23 (1989) 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Journal of Biomedical Materials Research 23 (1989), S. 1247-1259 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The in vivo biocompatibility of metals coated with several different types of ceramics [alumina (α-Al2O3), titanium oxide (TiO2), titanium nitride (TiN), and hydroxyapatite (HAP)] was investigated. These composites had been devised for the purpose of incorporation into the stem of a total hip prosthesis. The materials were inserted into the mid-diaphyseal region of the femurs of adult dogs, and follow-up quantitative histological comparisons were performed for a period of up to 96 weeks. HAP-coated composites showed the best biocompatibility.
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    Journal of Biomedical Materials Research 23 (1989), S. 1261-1270 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Human serum was incubated with representative portions of polyvinyl chloride (PVC) blood storage bags and vascular prostheses. The in vitro interaction process with lipo-protein was followed by polyacrylamide gel electrophoresis (PAGE) using sudan black and nitroblue tetrazolium (NBT) in the prestaining procedure. Densitometric scan of all the lipoprotein bands in serum after incubation with PVC bag material when prestained with sudan black showed remarkable increase in intensity. However, in the same experiment when NBT was used for prestaining no increase in the intensity of any of the lipoprotein bands could be observed. Since sudan black is known to bind cholesterol specifically we suggest that a molecular unfolding occurs when lipoprotein interacts with PVC bag material. When similar experiments were carried out with vascular prosthesis there was conspicuous decrease in the intensity of the high-density lipoprotein (HDL) band especially when stained with NBT. This indicates preferential adhesion of HDL during interaction with vascular prosthesis.
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    Journal of Biomedical Materials Research 23 (1989), S. 1195-1211 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The use of short glass fibers as a filler for dental restorations or cement resins have not been examined extensively. The mechanical properties and untreated glass fibers (5 μm dia × 25 μm) in Bis-phenol A glycidyl methacrylate (BIS-GMA) diluted with triethylene-glycol dimethacrylate (TEGDMA) resin were investigated for possible use as a restorative dental composite or bone cement. Compression, uniaxial tension and fracture toughness tests were conducted for each filler composite mixtures of 40, 50, 60 and 70%. Set time and maximum temperature of polymerization were determined. The results show that the elastic modulus, tensile strength and compressive strength are dependent on the percent of filler content. Elastic modulus and compressive yield (0.2%) strength of silane treated glass fibers filled composite increased from 2.26 to 4.59 GPa and 43.3 to 66.6 MPa, respectively, with increasing the filler content while the tensile strength decreased from 26.7 to 18.6 MPa. The elastic modulus of the untreated composite was less than that of the silane treated fiber composite. The tensile strength and compressive strengths were 20 to 50% lower than those of silane treated composites. The fracture toughness of the silane treated glass fiber additions were not significantly different from the untreated additions. The highest fracture toughness was obtained at 50% filler content with 1.65 MPa m.5. Set time increased from 3.5 to 7.7 minutes with increased filler content and peak temperature dropped from 68.3 to 34°C. The results of this study indicate that the addition of silane coated glass fiber to BIS-GMA resin increased the elastic modulus, tensile and compressive strengths compared with non-treated fibers. The addition of either treated or non-treated fibers increased the set time of the material and decreased the maximum temperature.
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    Journal of Biomedical Materials Research 23 (1989), S. 1289-1297 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Bioactive glass fibers have been prepared and implanted in cortical defect and in muscle. The fibers can act as a substrate for bone apposition, when implanted in a cortical defect, and become incorporated in the new bone matrix. The same results were obtained when fibers were implanted in a muscle pouch together with bone marrow cells. An intense inflammatory reaction was observed when bioactive glass fibers were implanted in muscle; the reaction was milder when fibers were implanted in bone or in muscle together with bone marrow cells. This fact supports the hypothesis that osteogenic cells adhere in an early phase to the substrate and prevent recognition of the foreign material by inflammatory cells. This appears to be a fundamental condition for direct bone matrix apposition on the surface of fibers.
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    Journal of Biomedical Materials Research 23 (1989), S. 1299-1313 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: This article deals with the in vivo evaluation of a new class of synthetic polypeptides, the poly[(tert-butyloxycarbonylmethyl) glutamates], POMEG, as an injectable or implantable drug delivery system. Three different polymers, varying in their degree of esterification, were extruded either with or without progesterone, and finally implanted in rats up to 14 days. Histologic evaluation of the implant sites show evidence of the good biocompatibility of these polymers. In addition, the description of their in vivo behavior, based on microscopic observation of the implanted POMEG rods, enables one to appreciate their potential as a drug delivery system for short- or long-term therapy.
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    Journal of Biomedical Materials Research 23 (1989), S. 1327-1342 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Biocompatibility and diffusional characteristics of recently synthesized unique amphiphilic newtworks, i.e., copolymers of methaycryloyl-capped polysiobutylene (MA-PIB-MA) with 2-(dimethylamino)-ethyl methacrylate (DMAEMA) have been examined. Excellent biocompatibility and biostability were obtained after 7 weeks with films containing 53-58% MA-PIB-MA implanted dorsally or abdominally in rats. In contras, neworks with higher or lower MA-PIB-MA contents showed decreased biocompatibility. These amphiphilic networks were also studied as potential implantable drug release systems. Bromophenol blue and folic acid were used as model compounds for drug release. Diffusion of these chemicals from loaded networks into water showed a marked pH dependence. Under specific well-defined conditions (MA-PIB-MA/DMAEMA content, pH, time range) release was observed to be independent of time (zero-order release).
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    Journal of Biomedical Materials Research 23 (1989), S. 1271-1288 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A series of copolymers of glycine and DL-lactic acid with various compositions was synthesized and their in vivo and in vitro degradation behavior was studied. For the in vivo examination, discs of the copolymer films were subcutaneously implanted in rats. The in vitro studies were carried out in phosphate buffer at pH = 7.4 and 37°C. The decrease in molecular weight, the loss of weight, and the tissue reactions of the different copolymers were determined after 2, 5, and 10 weeks. Poly(DL-lactic acid) was used as reference material. The in vivo and in vitro degradation behavior of the polymers was comparable. The decrease of molecular weight of the copolymers and poly(DL-lactic acid) in time was similar. The weight loss for copolymers with a higher mole fraction of glycine units started earlier. The copolymer with the highest content of glycine units disappeared completely within 10 weeks both in vivo and in vitro. The poly(DL-lactic acid) implant lost only 25% weight over the same period. Tissue reactions against all materials started with an acute inflammatory reaction caused by the trauma of implantation, followed by wound-healing processes, ending in a very mild foreign body reaction for the poly(DL-lactic acid) and a more excessive macrophage mediated foreign body reaction for the glycine/DL-lactic acid copolymers. The tissue reaction was more severe for polymers having a higher rate of degradation.
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  • 56
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    Journal of Biomedical Materials Research 23 (1989), S. 1343-1354 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Assessments were made of the safety of antibodies which might be detached from a therapeutic immunoadsorbent (IA) during extracorporeal circulation, with respect to possible immunological responses to such antibodies. The IA used was antihuman IgE antibody (a-IgE Ab) immobilized on a carrier, for removal of IgE from patients' plasma. The antibody was raised in goats and isolated to give an IgG fraction. This fraction was either used without further purification or was subjected to immunoaffinity purification. The active anaphylaxis test in guinea pigs indicated that positive responses were not observed at doses of less than 0.1 μg of goat IgG per animal. Rabbits given goat IgG intravenously 3 times a week for 8 weeks did not produce the specific antibody against goat IgG at doses of less than 0.05 μg/kg, which corresponds to less than 3 μg for an adult with a body weight of 60 kg. However, none of the rabbits given goat IgG at 2.5 mg/kg showed any toxic reactions and different patterns of the body weight growth from these in the control group. In addition, we tested whether immunoaffinity purified a-IgE Ab could trigger Type I hypersensitivity in a monkey model. Anaphylactic reactions were not observed after a single intravenous injection of a-IgE Ab at less than 10 μg/kg. These in vivo results are useful to judge whether the amount of antibody that leaks from a therapeutic IA is acceptable or not in a clinical situtation.
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    Journal of Biomedical Materials Research 23 (1989), S. 1315-1326 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: The present article builds on elementary fluid dynamics and previous analyses by the author to delineate approximate boundaries of mural thrombus height HP, maximum shear rate \documentclass{article}\pagestyle{empty}\begin{document}$ \dot \gamma _{{\rm Max}} $\end{document}, and flow pulsatility beyond which thrombi are subject to either very high or very low probabilities of embolization. A thrombus height of ∼0.1 mm emerges as a critical dividing line: Below it, the maximum embolizing shear stress τs is independent of thrombus height and varies only linearly with shear rate. Above it, τs quickly approaches a strong quadratic dependence on both thrombus height and shear rate: \documentclass{article}\pagestyle{empty}\begin{document}$ \tau _{\rm s} \sim (H_{\rm p} \dot \gamma)^2 $\end{document}, significantly increasing the likelihood of an embolizing event. By contrast, convective-diffusive removal of blood components during the initial stages of thrombus formation varies only weakly with \documentclass{article}\pagestyle{empty}\begin{document}$ \dot \gamma ^{{1 \mathord{\left/ {\vphantom {1 3}} \right. \kern-\nulldelimiterspace} 3}} $\end{document} in all but the smallest vessels. These maximum embolizing stresses are due principally to fluid drag. Acceleration (pulsatile) forces only begin to make their presence felt at \documentclass{article}\pagestyle{empty}\begin{document}$ {\dot \gamma} $\end{document} 〈 500 s-1 and reach parity with fluid drag at \documentclass{article}\pagestyle{empty}\begin{document}$ {\dot \gamma} $\end{document} ∼ 10 s-1, i.e., at a level where the presence of pulsatility is questionable. The results are used to provide maps of domains with high and low probabilities of an embolytic event and of vessel patency. The maps reveal that relatively modest changes in shear rate and/or vessel lumen can cause shifts from high to low likelihood of vessel patency, opening up possible ways of controlling blockage by manipulation of these variables.
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    Journal of Biomedical Materials Research 23 (1989), S. 1355-1365 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Notes: Glutaraldehyde (GA) and formaldehyde (FA) were shown to be released from 1 cm2 fixed pericard patches into 2-mL storage solutions after three 2-min washings in concentrations of about 1 mg/L. The cytotoxicity of these aldehyde concentrations on bovine aortic endothelial cells (BAECs) was evaluated in vitro, by proliferation capacity, cellular ATP content, PGI2 release and cyclic AMP synthesis. Continuous incubation of BAECs with GA 〉 0.1 mg/L and FA 〉 0.5 mg/L resulted in a significantly inhibited proliferation and in an increase of the intracellular Ca2+ triggered parameters, PGI2 and cyclic AMP, up to three fold. This strongly suggests an aldehyde-induced inhibition of the plasmamembrane bound Ca2+-ATPase, an enzyme which normally maintains low intracellular Ca2+-level. From these findings there is evidence that aldehydes released from bioprosthetic valve tissue may contribute to the lack of endothelial cell coverage in human implants.
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    Journal of Biomedical Materials Research 23 (1989), S. 1367-1369 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Journal of Biomedical Materials Research 23 (1989), S. 1369-1371 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Journal of Biomedical Materials Research 23 (1989) 
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    Journal of Biomedical Materials Research 23 (1989), S. 1373-1380 
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    Keywords: Chemistry ; Polymer and Materials Science
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  • 63
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    Notes: The synthesis of a triblock copolymer poly-(N-acetylethyleneimine)-polyethylenoxide-poly(N-acetylethyleneimine) includes two successive steps: the first is the functionalization of a poly(ethyleneglycol) precursor by creating sulfonic esters at its chain ends, the second uses these esters to initiate the cationic polymerization of 2-methyl-2-oxazoline. Homopolymers appear in the raw product; hence successive selective extractions of the copolymer with benzene and dioxane are necessary. The final yield in pure copolymer was 11%. The copolymer was characterized by UV and 1H-NMR spectrometry and light scattering. Adsorption isotherms were determined on silica, for varying pH and salt concentration. Optimum conditions for coating silica with the polymer were determined. The efficiency of this precoating to reduce the adsorption of fibrinogen was very high (99.2% reduction with respect to bare silica). Steric exclusion chromatography of a variety of proteins gave a satisfactory calibration curve. Platelet accumulation on copolymer precoated glass was reduced to 10-20% of its value on bare glass, a result superior to that obtained by albumin passivation of the same glass surface.
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    Journal of Biomedical Materials Research 23 (1989), S. 1411-1422 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: A technique using 125-I-labeled proteins was employed to study static adsorption properties and slow exchange and desorption processes of human albumin in contact with synthetic hydroxyapatite beads. With the aid of a thermostated “minicolumn,” the adsorption isotherm was obtained during a so-called multiadsorption process, and could be described by a Langmuir adsorption model (K = 1.10 × 1010 cm3 · mol-1). All kinetic desorption and exchange experiments could be fitted by a simple exponential function of time. No influence of long-term interfacial residence times on characteristic relaxation times or percentage of desorbed or exchanged proteins could be detected in the present system. On the other hand, as compared to the low surface coverage domain, the small percentage of desorbable and high percentage of exchangeable molecules in the adsorption plateau domain was attributed to a bimolecular exchange process.
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    Journal of Biomedical Materials Research 23 (1989), S. 1385-1393 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: Glass and silica beads were precoated with various polymers to obtain steric exclusion chromatography (SEC) supports which are nonadsorbant for hydrophilic macromolecules. The efficiency of this treatment was estimated by subsequent radiolabeled fibrinogen adsorption. The result obtained with a block copolymer was better than with various hydrophilic homopolymers. This ABA type block copolymer, where A is a poly(N-acetylethyleneimine) (PAEI) sequence and B a polyethylene oxide (PEO) sequence was preadsorbed at pH 4.5 and 25°C; the fibrinogen adsorption was reduced to less than 5% of the value observed on untreated solid surfaces. Thus the hemocompatibility of solid supports should be increased by precoating with this block copolymer. Results for nonporous glass beads and porous silica particles were in good correlation.
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    Journal of Biomedical Materials Research 23 (1989), S. 1423-1432 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: A new artificial connective matrix which results from two reactions of fibrinogen and fibronectin on elastin was used to obturate a slit made in the abdominal aorta of rabbit. The so-called Elastin - Fibrin biomaterial behaved as a scaffold through which all the different structures were restored to their former condition. At 3 months, the material had disappeared and no thrombus, no inflammation or reject had been detected.
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    Journal of Biomedical Materials Research 23 (1989), S. 1433-1440 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: Gingival fibroblasts were cultured with four different calcium phosphate minerals (hydroxyapatite, whitlockite, b̃-tricalcium phosphate, and octocalcium phosphate). 3H-thymidine incorporation into DNA and alkaline phosphatase specific activity were determined after different incubation periods. As a consequence of the phagocytosis of calcium phosphates crystals, we pointed out, compared to control, a stimulation of the rate of 3H-thymidine incorporation and sharp decreases in alkaline phosphatase activity. The magnitude of the alkaline phosphatase activity inhibition was observed to be increased with the solubility of the materials. We propose that the effects of calcium phosphates on alkaline phosphatase and 3H-thymidine incorporation could be calcium-mediated events, resulting from intracellular dissolution of phagocytized materials. We suggest that in vitro determination of 3H-thymidine incorporation and alkaline phosphatase activity, which are highly sensitive tests, could be involved in evaluation procedures of calcium phosphates biomaterials.
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    Journal of Biomedical Materials Research 23 (1989), S. 1441-1452 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: A technique for promoting vascularization of a polyurethane sponge is demonstrated in the present study. Collagen-impregnated polyurethane sponges (Hypol, 2002) Foamable Hydrophilic Prepolymer (FHP) were implanted in the femoral fossa of rats for 1 day to 6 weeks. The ligated femoral artery/vein was pulled through the sponges to facilitate more complete neovascularization. Light-microscopic evaluation of the implanted sponges revealed that significant vascularization had occurred by the seventh day of implantation, and was maximal by the fourth to sixth week. Sponges containing collagen had a more thorough vascularization process than sponges without collagen, perhaps due to a more uniform pore size as demonstrated by scanning EM. Time course studies suggested that the artery/vein pull-through enhanced the development of the neovascularization process in the center of the sponges. We conclude that significant vascular tissue in-growth can be developed in polyurethane sponges and that both collagen and centrally placed blood vessels help promote the vascularization process. Potential applications could extend to a variety of bioartificial systems including endocrine or hepatic transplantation, softtissue prosthetic materials, bone grafts, or drug delivery systems. Further studies would be useful in providing additional information on the factors promoting neovascularization, and on the potential applications of this methodology using the present or similar biomaterials.
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    Journal of Biomedical Materials Research 23 (1989), S. 1505-1507 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Journal of Biomedical Materials Research 23 (1989) 
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    Journal of Biomedical Materials Research 23 (1989), S. 1483-1504 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: An investigation has been made of the protein layers formed on hemodialysis membranes during clinical use. Dialyzers having membranes of polymethylmeth-acrylate (PMMA), Cuprophane, cellulose acetate (CA), and saponified cellulose ester (SCE) were examined. Immediately following dialysis the dialyzers were washed free of blood and the membranes eluted with 2% SDS. The eluates were examined by SDS-PAGE followed by protein immunoblotting. Antisera to 16 common plasma proteins were used to probe for the presence of these proteins in the eluates. Most of the proteins tested for were found in the different eluates, suggesting that the protein layers are extremely complex. The protein compositions were qualitatively different on the different membranes. Except for HMWK the contact phase clotting factors were present in very small amounts and were largely activated. The clear presence of HMWK and the relatively small amounts of fibrinogen provide support for the occurrence of the Vroman effect. Fibrinogen was found to be degraded and this may be related to the observation that plasminogen was activated to plasmin. Complement C3 was an abundant component of all eluates. It was degraded to small fragments in a way which could not be related to complement activation. Many of the other proteins, particularly those of high molecular weight, were extensively degraded. It is speculated that this heretofore unremarked phenomenon may be due to the action of enzymes released by cell damage.
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    Notes: We report a novel method for rapid comparison of the relative strength of adhesion of cells to different solid surfaces. A vertically oscillating micropipette is brought above an individual cell in such a manner that it makes contact with the cell at the lower limit of its travel. The pressure within the micropipette is gradually reduced until the cell attaches to the micropipette by suction and is lifted from the solid surface. The reduction in pressure required to detach a cell depends on the specific cell-substrate combination and serves as a relative measure of the strength of cell adhesion. A particular advantage of this approach over conventional methods is the ability to select particular cells from a population. As a test of the reproducibility of the method and its ability to distinguish the strength of adhesion of cells to different solid surfaces, we have used it to measure the adhesiveness of human red blood cells to hydrophilic glass, tissue culture grade polystyrene, polyethylene terephthalate, and polymethyl methacrylate. We find that results for the same surface are highly reproducible and that the method is capable of distinguishing small differences in the adhesiveness of red blood cells to the above surfaces.
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    Journal of Biomedical Materials Research 23 (1989), S. 3-7 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Journal of Biomedical Materials Research 23 (1989), S. 87-104 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: Surfaces of commercial polyurethanes (PUs) were modified by poly(ethylene oxide) (PEO) grafting and/or heparin immobilization for long-term biomedical applications. PU surfaces were treated with diisocyanate and then reacted with PEO or heparin. The heparin immobilized by various methods on the PU surface was very stable, with concentrations of 1.45-1.84 m̈g/cm2. Surface structure and characteristics of each modified PU were examined by performing the following surface analyses: attenuated total reflection infrared (ATR-IR), electron spectroscopy for chemical analysis (ESCA), scanning electron microscopy (SEM), and dynamic contact angle measurements. The reaction scheme and surface chemical structure of modified PUs were confirmed by ATR-IR and ESCA, respectively. SEM results showed that the PU-PEO surface was very smooth and that the smoothness of the heparinized PU surfaces varied, depending upon the solvent and coupling agent used in the process. The hydrophilicity of the surface was significantly increased after PEO grafting or heparin immobilization. Increase in the chain length of the grafted PEO resulted in significant increases in hydrophilicity and surface mobility.
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    Journal of Biomedical Materials Research 23 (1989), S. 129-143 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: Because needle bending resistance is such an important factor in the selection of surgical needles, a standard quantitative test of needle bending has been devised to study the biomechanics of deformation of needles from three different commercial manufactures. The superior resistance to deformation of needles made by one manufacturer has been related to the specific alloy, ASTM 45500 stainless steel, employed in its production. The needles produced from ASTM stainless steel 45500 have stronger tensile and yield strengths than those of the other alloys, accounting for their greater resistance to bending.
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    Journal of Biomedical Materials Research 23 (1989), S. 145-152 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: A new method using an image processing system developed in our laboratories is used to measure the pore size in Mersilene, Marlex, and Teflon surgical meshes. All three meshes appear to have sufficiently large pores and should facilitate tissue growth/attachment. Results obtained in this study are compared to results of an earlier paper.
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    Journal of Biomedical Materials Research 23 (1989), S. 105-116 
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    Notes: Orthopaedic internal fracture fixation plates are subjected to combined axial, bending, and torsional loads in vivo which can cause screw loosening and implant failure. This paper outlines a relatively simple technique which allows controlled application of combined axial, bending, and torsional loading to examine the loosening rate of cortical screws used to attach these plates. Fiber reinforced polycarbonate rods with a tensile strength similar to that of cortical bone were cut at half their length to simulate fractured tibii. These were compression plated using a standardized technique and placed in a loading fixture. Joint loads at the knee determined from force plate analysis and statics were applied to a plated fixture during testing. The design of the fixture allowed adjustment of the proportion of bending and torsional loads applied to the test samples. It also allowed a reproducible means of applying a predetermined axial, bending, and torsional load. Screw loosening following cyclical loading was evaluated by measuring the amount of angular displacement required to retighten screws to a prescribed torque value. A torque wrench was modified to allow the measurement of these displacements.
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    Journal of Biomedical Materials Research 23 (1989), S. 269-271 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Journal of Biomedical Materials Research 23 (1989), S. 117-128 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Topics: Medicine , Technology
    Notes: The implantable ventricular assist systems currently undergoing clinical readiness testing shuttle the displaced gas between the non-blood side of the pumping diaphragm and an elastic chamber generally called a “compliance chamber” or variable volume device. The movement of the stored gas allows the pump to fill and empty without compression or expansion of the gas behind the pump diaphragm. The material used for the construction of compliance chambers should be fatigue resistant to withstand the 63 million flexes per year of the blood pump. The material should also be biocompatible and highly impervious to gases. Significant diffusion of gases from the compliance system necessitates external make-up gases to somehow be added to the internal system. Material selection is complicated by the fact that most fatigue-resistant elastomers also have high gas permeability. In order to solve this problem, bilayer compliance chambers have been developed using biocompatible and fatigue-resistant polyolefin rubber comolded with relatively impervious butyl rubber.
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    Journal of Biomedical Materials Research 23 (1989), S. 311-319 
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    Notes: A commercially available mammary implant containing a soft polyester polyurethane foam shell has been examined for possible diamine hydrolysis products. Fourier Transform Infrared (FT-IR) analysis has shown ester and aromatic structures present in the intact foam shell Vigorous hydrolysis conditions using NaOH have produced a mixture with large amounts of toluene diamine (TDA) present as determined by Gas Chromatography-Mass Spectrometry (GC/MS), and GC/FT-IR. There are numerous clinical reports of the degradation of this implant shell after implantation with incorporation of fragments into phagocytic cells at the implantation site. Recent reports have discussed late pain and other allergic reactions to this implant. Release of the known toxic material, TDA, is consistent with these observations and strongly suggests that an alternative material be used in this application.
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    Journal of Biomedical Materials Research 23 (1989), S. 1-16 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: A biodegradable particulate composite bone cement consisting of a crosslinked gelatin matrix and tricalcium phosphate particles was implanted intraosseously in rabbits for up to 12 weeks. Cured cylindrical implants were inserted in holes drilled in the proximal tibial metaphysis. Sequential fluorochrome labeling and radiographs were done, and specimens were processed for decalcified and nondecalcified histology. At 4 weeks, the cross-sectional diameter of the implant was slightly greater than at implantation. There was considerable dissolution of the matrix and some new bone ingrowth. At 12 weeks, the diameter was reduced to half the original diameter and bone had grown throughout the matrix. In the distal femur, freshly mixed cement was used to stabilize an osteochondral fracture. Mechanical testing of the cement-stabilized fracture revealed a decrease in compressive strength and modulus at 4 weeks followed by an increase to greater than initial values at 12 weeks. Over time, the osteochondral fragment subsided into the underlying cement, but the subsidence did not correlate with mechanical strength. This osteochondral fracture model permits measurement of the overall material properties of a cement simultaneously weakened by resorption and reinforced by ingrowing bone.
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    Journal of Biomedical Materials Research 23 (1989), S. 81-90 
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    Keywords: Chemistry ; Polymer and Materials Science
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    Notes: One aim of this in vitro investigation was to determine the effect of substituting four phenols and two methacrylates with vinyl functions on the dentin bond strengths of several new experimental dentin bonding agents. Another objective was to determine the effect of postextraction age and dentin level within the tooth on tensile bond strengths of these toluene diisocyanate-derived adhesives. Extracted third molars were divided into postextraction age groups and sectioned into three slices ∼400 m̈m thick. The four substituted phenols were: eugenol, o-methoxyphenol, o-chlorophenol, and p-cresol. Substituted methacrylates with vinyl ligands were 2-hydroxyethyl methacrylate (HEMA) and 6-hydroxyhexyl methacrylate (HHMA). Results showed that adhesives made with o-chlorophenol, p-cresol, and methoxyphenol with HEMA were the best, while those made with eugenol and HHMA were the worst. The post extraction age of the tooth and the dentin depth had no consistent effect on most adhesive bond strengths which were generally around 10.3 MPa (1500 psi).
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    Journal of Biomedical Materials Research 23 (1989), S. 125-133 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Tissue biocompatibility of cellulose and its derivatives was examined in two in vivo tests, one for absorbance by living tissue and one for foreign body reaction. The samples examined were regenerated celluloses and cellulose derivatives: methylcellulose, ethyl cellulose, aminoethyl cellulose, hydroxyethyl cellulose, and cellulosic polyion complexes. The in vivo absorbance by living tissue was found to depend on the degree of crystallinity and the chemical structure of the sample. The foreign body reaction was relatively mild for all the samples examined, showing that cellulose can be converted to biocompatible materials by physical and/or chemical transformation.
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    Journal of Biomedical Materials Research 23 (1989), S. 157-169 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The adsorption of fibrinogen from both human whole blood and plasma to a number of “foreign” surfaces is reported. Adsorption was measured as a function of plasma or blood dilution using radioiodine labeling. We showed previously that adsorption of fibrinogen from plasma exhibits a maximum at a plasma dilution of about 100:1, and have attributed this behavior to competition from other plasma proteins. (The same phenomenon is manifest as a time transient in fibrinogen adsorption.) In the present work we show that exactly the same trends are observed in whole blood. For each of the four surfaces, glass, siliconized glass, collagencoated glass and polyethylene, the adsorption of fibrinogen as a function of dilution is the same in whole blood as in plasma. Each of these surfaces shows a unique dependence of fibrinogen adsorption on plasma or blood dilution. On cuprophane and a hydrophilic polyether urethane there is essentially no adsorption of fibrinogen from blood or plasma. For the hydrophilic polyurethane this result may be artifactual, but the absence of fibrinogen binding to cuprophane in blood or plasma is real since fibrinogen is found to be adsorbed in monolayer amounts from buffer.
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    Journal of Biomedical Materials Research 23 (1989), S. 267-279 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Random copolypeptides and block copolypeptides were synthesized, and an interaction between these polypeptide membranes and the cells was studied by a cell culture method (cell line, Ca. 9.22). In random copolypeptides composed of γ-methyl L-glutamate and γ-benzyl L-glutamate, cell attachment and cell growth depended on the monomer composition, and showed a maximum at around 70 mole % of benzyl glutamate. Block copolypeptide composed of L-methionine and oxyethylene exhibited low cell attachment and cell growth even at 10 mole % of oxyethylene content, compared to L-methionine homopolymer. ESCA study of the membrane suggested this result to be due to concentration of the poly(oxyethylene) block chain of the polymer on the surface of the membrane. Block copolypeptide composed of N5-(3-hydroxypropyl) L-glutamine and L-leucine exhibited low cell attachment and cell growth, while the corresponding random copolypeptide exhibited high cell attachment and cell growth. This difference is attributable to the microheterophase structure with the hydrophilic domains embedded in the hydrophobic matrix in the block copolypeptide membrane.
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    Journal of Biomedical Materials Research 23 (1989) 
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    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 88
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    Journal of Biomedical Materials Research 23 (1989) 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Journal of Biomedical Materials Research 23 (1989), S. 285-294 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The luminal surfaces of polyethylene and polyurethane tubings of 1 mm inner diameter and 1 m in length were coated with heparin by end point attachment and thereafter sterilized in ethylene oxide. The tubings were inserted as arterio-venous shunts from the aorta to the superior caval vein via a carotid artery and a jugular vein. Patency was assessed with an ultrasound doppler flow meter and flow measurements. All nonheparinized shunts occluded within 10 days with a mean elapsed time from the insertion of the tubing is the last positive doppler registration being 3.5 days. The corresponding patency time for heparinized shunts was 25.9 days. The occlusion of the heparinized tubings was due to the incorporation of the ends of the tubings in the walls of aorta and caval vein, whereas the nonheparinized tubings occluded as a result of clot formation. It is concluded that surface immobilization of heparin with sequences capable of activating antithrombin may be beneficial in the development of small-diameter vascular protheses.
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    Journal of Biomedical Materials Research 23 (1989), S. 295-309 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A series of methacrylate oligomers containing pendant isocyanate groups were synthesized by reacting 2-isocyanatoethyl methacrylate (IEM) and/or m-isopropenyl- α, α-dimethylbenzyl isocyanate (TMI) in ethoxyethyl acetate with methacrylates ranging from methyl to stearyl methacrylate or allyl-, cyclohexyl-, glycidyl-, i-bornyl-, or dicyclopentenyloxyethyl methacrylate. The oligomers which are stable at room temperature were characterized by IR for NCO, ester, and C = C groups and by their refractive indices. They have a small number of residual double bonds and a molecular weight low enough so that the compounds are liquids at room temperature and dissolve readily in esters and chlorinated hydrocarbons. HPLC showed no residual monomer. GPC and intrinsic viscosity of selected oligomers indicated a molecular weight range from 1400 to 2600. Isocyanate groups were determined titrimetrically and ranged from 15.9% to 5.1%. Concurrent studies have demonstrated that these oligomers bond strongly to hard and soft tissues. Thus, subject to their biocompatibility they could find many applications as tissue adhesives.
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    Journal of Biomedical Materials Research 23 (1989), S. 351-368 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Polyethylene oxide(PEO)-containing non-ionic polymeric surfactants were studied as a possible means to produce PEO-rich surfaces by a simple coating treatment of a common hydrophobic medical material - polyethylene. Surface tension and adsorption properties of PEO/polypropylene oxide(PPO) and PEO/polybutylene oxide(PBO) block copolymer surfactants on a hydrophobic surface (low density polyethylene, LDPE) were investigated, using the Wilhelmy plate surface tension technique and x-ray photoelectron spectroscopy(XPS). The protein resistance of the surfactant-treated surfaces was evaluated by XPS and 125I-labeled proteins. The data presented indicate that adsorption of the surfactants on LDPE is dependent on the molecular geometry of the surfactants. Adsorption of human albumin was significantly decreased on the surfactant-treated LDPE surfaces, as compared with the untreated surface. Surfactants suitable for the preparation of PEO-rich surfaces and possible mechanisms for their protein resistance are discussed.
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    Journal of Biomedical Materials Research 23 (1989), S. 443-450 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Information obtained from physical and chemical characterization of vascular grafts can prove valuable in obtaining a preliminary assessment of potential in vivo performance. The data presented illustrate the concept and show that the new biological graft made from bovine ureters has adequate performance characteristics for use as a potentially successful vascular graft.
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    Journal of Biomedical Materials Research 23 (1989) 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Journal of Biomedical Materials Research 23 (1989), S. 491-506 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Our previous two articles have shown that glutaraldehyde-fixed bovine pericardium is nearly isotropic, whether fixed without constraints, with tethering, or with pressure. In this study, we have used uniaxial stress during fixation to produce bovine pericardial material with marked tensile anisotropy. Rectangular and cruciate pericardial samples have been mechanically examined after one of four treatments: (i) fixation under 88-kPa uniaxial stress, (ii) fixation under 176-kPa uniaxial stress, (iii) 3 h of 176-kPa uniaxial stress in saline followed by 24-h fixation under the same stress, (iv) fixation under 176-kPa uniaxial stress followed by a second fixation under 176-kPa stress in a direction normal to the first. Strips of material were cut at 0°, 30°, 60°, and 90° to direction of the initial stress, and tested for response to cyclic loading, stress relaxation, plastic deformation, and fracture properties. Fixation under uniaxial stress produced anistropy similar to that seen in porcine aortic valve leaflets; however, the overall extensibility of the material depended on the applied stress and the aspect ratio of the stressed sample. While loading in saline produced no change, the sequential biaxial stressing produced a reduction in anisotropy, suggesting exposure of additional crosslinking sites. Uniaxial stress during fixation may be a useful method for construction of anisotropic heart valve leaflets.
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    Journal of Biomedical Materials Research 23 (1989), S. 535-548 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: These studies involved the evaluation of human monocyte/macrophage activation by biomedical polymers coated with human blood proteins. The biomedical polymers were polyethylene, polydimethylsiloxane, woven Dacron fabric, expanded polytetrafluoroethylene, Biomer®, and tissue culture treated polystyrene as the control. They were adsorbed with human blood proteins: albumin, fibrinogen, fibronectin, hemoglobin, and gamma globulin. The protein adsorbed polymers were evaluated for their potential to activate the monocyte/macrophage cellular population in vitro as assessed by the induction of the monocyte/macrophage inflammatory mediator, Interleukin 1 (Il1). Suppression of IL1 was observed when protein adsorbed polymers were compared to the appropriate protein adsorbed control. Protein adsorbed polymers, when compared to polymers without protein adsorption, stimulated IL1 production. The data presented in this manuscript show the level of induction and secretion of IL1 was dependent on the biomedical polymer and the protein adsorbed, as well as the requirement of lipopolysaccharide. These results show differential interactions occur between the proteins, monocytes/macrophages, and biomedical polymers which alter activation and induction of IL1.
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    Journal of Biomedical Materials Research 23 (1989), S. 631-648 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: In this study, it was found that a Ca—P layer and a Si layer were formed on the interface of the mother glass of apatite-wollastonite containing glass-ceramics (designated AW) and bone tissue. The dissolution of Si, Ca, and P from glass (MgO—CaO—SiO2—P2O5—CaF2) is necessary to form a chemical film (a Si layer and a Ca—P layer). The three kinds of glasses used were (1) a mirror surface of the mother glass (MgO 4.6, CaO 44.9, SiO2 34.2, P2O5 16.3, CaF 0.5 weight ratio) of AW (designated G—AW (mirror)), (2) an abraded surface of G—AW (designated G—AW (#2000)), (3) a mirror surface SiO2 glass (designated G—Si, 100%SiO2). The glass plates (15 mm × 10 mm × 2 mm) were implanted into the metaphysis of tibia of mature male rabbits for 10 and 25 weeks. The failure load, when an implant detached from the bone or when the bone itself broke, was measured by a detaching test and the interface of glass/bone was observed by SEM-EPMA. Failure loads in G—Si, G—AW (mirror), and G—AW (#2000) 10 weeks after implantation were 0.18 ± 0.24, 3.06 ± 1.29, and 2.94 ± 1.77 kg, respectively. Those in G—Si, G—AW (mirror), and G—AW (#2000) 25 weeks after implantation were 1.30 ± 1.18, 3.88 ± 1.06, and 3.55 ± 1.51, respectively. The failure loads in G—Si vs. G—AW (mirror) and those in G—Si vs. G—AW (#2000) differed significantly (P 〈 0.01). There were no significant differences in the failure load according to the surface roughness of G—AW. As shown by SEM-EPMA observation, a Si layer next to G was adjacent to a Ca—P layer next to the bone. The chemical film showed no increase in thickness as time passed. A Ca—P layer did not form on the interface of Si—G and bone.
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    Journal of Biomedical Materials Research 23 (1989) 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Journal of Biomedical Materials Research 23 (1989), S. 705-718 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The peritoneal cavity is a convenient site for implantation of encapsulated hormonesecreting tissue. However, host tissue organization around such implants may affect solute exchange and viability of the encapsulated tissue. The reaction to polyvinyl chloride acrylic copolymer capsules implanted in the peritoneal cavity of rats and mice was therefore studied. Some animals received a slow release dexamethasone pellet, others were pretreated with doxorubicin, in an attempt to minimize the tissue reaction. The tissue reaction was significantly thicker in rats than in mice at both 2 and 6 weeks after implantation. In rats, corticoids decreased significantly the thickness of the reactive layer as compared to control at all time points studied, but doxorubicin had no effect. The tissue reaction in mice was not significantly affected by corticoid treatment. In both species the thickness of the tissue reaction did not increase significantly between 2 and 6 weeks. At 3 days the tissue reaction consisted of an interrupted single layer of macrophages in mice, whereas in rats the reaction consisted of two or three layers of macrophages and polymorphonuclear cells. At both 2 and 6 weeks, several cell layers surrounded the implants: a single layer of macrophages lying along the polymer, a variable number of layers of fibroblasts interspresed with collagen fibrils (fewer in mice than in rats, and fewer in corticoid treated rats than control rats) and an outer monolayer of mesothelial cells. We conclude that the intensity of tissue reaction to polymer implants in the peritoneal cavity is species dependent and can be decreased by the administration of corticoids but not doxorubicin.
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    Journal of Biomedical Materials Research 23 (1989), S. 809-811 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Journal of Biomedical Materials Research 23 (1989), S. 883-894 
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Specially prepared biphasic calcium phosphate (BCP) macroporous ceramics consisting of an intimate association of beta tricalcium phosphate (b̃-TCP) and hydroxyapatite (HA) with b̃-TCP/HA weight ratios of 15/85, 35/65, and 85/15 were implanted in surgically created periodontal osseous defects in dogs and recovered after 6 months. A decrease in average size of crystals in BCP ceramics and an increase in the size of microporosities in the surface and at the core of the ceramic after implantation were observed, indicating that in vivo dissolution has taken place. The resorbability (reflecting in vivo dissolution) of BCP ceramics depended on their b̃-TCP/HA ratios, the higher the ratio, the greater the resorbability. The formation of microcrystals with crystallographic properties and Ca/P ratio similar to those of bone apatite crystals were also observed. The abundance of these crystals were directly related to the b̃-TCP/HA ratio of the BCP ceramic before implantation. The formation of the bone apatite-like crystals may be due to the precipitation of calcium and phosphate ions released from the dissolving ceramic crystals (the b̃-TCP component dissolving preferentially to the HA component). Results from this study suggested that one of the means of controlling resorbability (in vivo dissolution) of BCP ceramic is by varying its b̃-TCP/HA ratio.
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