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  • Articles  (186)
  • Polymer and Materials Science  (186)
  • Genetics
  • Inorganic Chemistry
  • 1995-1999
  • 1990-1994  (186)
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  • 1992  (186)
  • Technology  (186)
  • 1
    Electronic Resource
    Electronic Resource
    Acrylic bone cements: Residuals and extractability of methacrylate monomers and aromatic amines (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 3 (1992), S. 51-57 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A new formulation of acrylic bone cement [methylmethacrylate/n-decylmethacrylate/isobornylmethacrylate (MMA/DMA/IBMA)] developed with the purpose of reducing the biologic adverse effects of bone cements was analyzed by high performance liquid chromatography for residual content of monomers and aromatic amines from the accelerator system [dimethyl-p-toluidine (DMPT), dihydroxypropyl-p-toluidine (DHPPT)] in the cured cement and for concentrations of these constituents in hydrophilic and lipophilic eluates. In comparison with conventional polymethyl-methacrylate acrylics a considerable reduction of both released and residual MMA was experienced, being about 10- to 15-fold. The residual content of the new DMA and IBMA monomers were 0.35% and 0.66%, respectively, in cured cement after 72 h and these could only be detected in the paraffin eluates. The residual content of aromatic amines was considerably reduced with the new cement formulation. No DMPT could be detected and the DHPPT represented a 3- to 4-fold reduction in cured cement and a 8- to 10-fold reduction in eluates. The residual DHPPT content of about 0.07% was found to be practically constant with time. It is concluded that MMA/DMA/IBMA cement cures faster and more completely.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jab.770030109
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  • 2
    Electronic Resource
    Electronic Resource
    The effect of a thin coating of polymethylmethacrylate on the torsional fatigue strength of the cement-metal interfaceSupported by the William H. Harris Foundation, Boston, MA 02114. (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 3 (1992), S. 45-49 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Recent studies have established that a mechanism of initiation of failure of fixation of cemented femoral components is debonding of the cement-metal interface. Other studies have shown that the torsional forces induced by stair climbing and rising from a chair are very high. Thus, the interface between the femoral prosthesis and the bone cement in total hip arthroplasty (THA) is required to transmit high torsional loads from the metal to the cement in a cyclic shear mode many times per year. These torsional loads likely contribute to the debonding. This study evaluated the efficacy of a thin layer of polymethylmethacrylate (PMMA) precoating in increasing the torsional fatigue strength of the cement-metal interface. Fatigue studies were performed on 15 specimens. Each specimen was tested with and without PMMA precoating. The PMMA precoat significantly and substantially increased the torsional fatigue strength of the cement-metal interface. Thus, PMMA precoating is likely to be a clinical advantage in maintaining the long-term integrity of the cement-prosthesis interface.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jab.770030108
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  • 3
    Electronic Resource
    Electronic Resource
    The academic environment of biomaterials science and engineering (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 3 (1992), S. 63-71 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jab.770030111
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  • 4
    Electronic Resource
    Electronic Resource
    Thrombus deposition on polyurethanes designed for biomedical applications (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 3 (1992), S. 167-176 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Thrombogenicity was assessed by measuring the amount of 111In-platelets and 125I-fibrinogen deposited on the inner luminal surface of six polyurethanes for up to 60 min of blood contact in a canine ex-vivo shunt model. Commerical and laboratory synthesized polymers were examined. Two of the commercially synthesized polyurethanes (Biostable PURs) do not contain ether linkages in the polymer backbone and have previously shown resistance to oxidative and hydrolytic degradation. Static contact angle measurements, dynamic contact angle measurements, and ESCA were used to characterize the surfaces of these polyurethanes. The effectiveness of an acetone extraction used to remove extrusion waxes from Pellethane 2363-80A was similarly studied. Both Pellethane 2363-80A and the ether-free materials had relatively nonthrombogenic surfaces, as indicated by low platelet and fibrinogen deposition, making them potentially good candidates for biomedical applications.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jab.770030302
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  • 5
    Electronic Resource
    Electronic Resource
    Histologic analysis of a retrieved expanded polytetrafluoroethylene posterior cruciate ligament (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 3 (1992), S. 183-190 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: An expanded polytetrafluoroethylene (PTFE) prosthesis used to reconstruct the posterior cruciate ligament in a 37-year-old Caucasian male was retrieved and histologically examined in this study. Backscattered electron (BSE) microscopy, utilized to observe the mineralized tissue ingrowth into the retrieved specimen, revealed an absence of bony ingrowth within the graft. Light microscopy demonstrated an exuberant foreign body giant cell response surrounding and invading the substance of the graft, and also revealed evidence of graft degradation. These observations indicate that PTFE may not be as favorable a material for reconstruction of ligamentous tissues as previously reported.
    Additional Material: 10 Ill.
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    URL: http://dx.doi.org/10.1002/jab.770030304
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  • 6
    Electronic Resource
    Electronic Resource
    The effect of thermoforming on the properties of fiber-reinforced composite wires (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 3 (1992), S. 177-182 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The effects of thermoforming on the instantaneous flexural properties and structure of thermoplastic fiber-reinforced composite (FRC) wires were studied to determine the preferred temperature range for clinical forming. Five different formulations of FRC wires were heated to clinically relevant thermoforming temperatures in a special mold that was designed to maintain their shape. In addition, one formulation was also heated without the restraining effect of the mold. Flexural properties were determined. A temperature above the Tg is necessary to allow sufficient softening and avoidance of distortion in shape during clinical forming. However, higher temperatures will result in significant structural disintegration of the wires with consequent decrease in flexural modulus. Thus, for every material, there is a heating range or “working range” where the material can be properly formed with minimal changes in the physical properties. This was primarily related to the Tg of the matrix used.
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/jab.770030303
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  • 7
    Electronic Resource
    Electronic Resource
    Effectiveness of silane treatment on absorbable microfibers (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 3 (1992), S. 191-195 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Preliminary experiments suggest pretreatment of absorbable crystalline, calcium-sodium-metaphosphate (CSM) microfibers with trimethoxy-based silane coupling agents yields a polysiloxane film barrier which protects the fiber surface from early dissolution due to water. Compared to thermoplastic poly(L-lactic acid) (PLLA) composites reinforced with untreated fibers, PLLA composites reinforced with a variety of silane pretreated microfibers showed increased mechanical properties, suggesting improved adhesion was achieved at the fiber/matrix interface. Unfortunately, the silane pretreated CSM/PLLA composite showed no increase in wet strength retention after short-term in vitro exposure. This may be due to plasticization from water entering the composite at areas of incomplete fiber wetting by the highly viscous molten PLLA. However, when a nonabsorbable, low viscosity unsaturated polyester thermoset resin was reinforced with methacryloxy-silane pretreated CSM microfibers, there was no decrease in flexural strength and less than a 10% decrease in flexural modulus after 7 days exposure to 7.4 pH Tris-buffered saline at 37°C.
    Additional Material: 3 Ill.
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    URL: http://dx.doi.org/10.1002/jab.770030305
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  • 8
    Electronic Resource
    Electronic Resource
    Alkyl cyanoacrylates as space filling bone adhesives (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 3 (1992), S. 207-210 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Higher chained alkyl cyanoacrylates have potential to function efficiently as space filling, hydrophobic, viscoelastic, biocompatible, and rapidly polymerizing bone adhesives. Hence they may be useful in applications where a void has to be filled, such as replacement of the intervertebral disc. To assess their applicability as space filling material in such an pplication, three alkyl cyanoacrylates; methoxyethyl cyanoacrylate, isobutyl cyanoacrylate, and isoamyl cyanoacrylate have been evaluated in this study. The bonding strength of these cyanoacrylates to bone in a space filling situation have been measured. The results indicate the bond strength of isoamyl cyanoacrylate (0.13 MPa) to be significantly (p 〈 0.05) lower compared with methoxyethyl cyanoacrylate (0.33 MPa) and isobutyl cyanoacrylate (0.37 MPa). There was no significant difference in the bond strengths of isobutyl cyanoacrylate and methoxyethyl cyanoacrylate.
    Additional Material: 1 Ill.
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    URL: http://dx.doi.org/10.1002/jab.770030307
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  • 9
    Electronic Resource
    Electronic Resource
    Biocompatibility tests on a novel glass-ceramic system (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 3 (1992), S. 217-224 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The aim of this study was to look at the bone bonding potential of six formulations of a novel glass-ceramic system. Cylinders of the ceramics were implanted in rabbit tibiae for 4 and 7 weeks. Histological tests, both quantitative and qualitative, as well as push-out tests, were carried out during the bonding assessment. Bone growth was quite prolific, even at 4 weeks, as evidenced by growth up to and along the implant surfaces. The interfacial shear strengths compared well with other biomaterials in use as endosseous implants. Therefore it seems pertinent to pursue further long-term experimentation with this material.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/jab.770030309
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  • 10
    Electronic Resource
    Electronic Resource
    Biocompatibility and mechanical properties of a totally absorbable composite material for orthopaedic fixation devices (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 3 (1992), S. 197-206 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Bioabsorbable polymer/inorganic phosphate fiber composites are prone to rapid degradation due to water sensitivity of the interface between the degradable polymer and the degradable fiber. This article describes successful fabrication and laboratory evaluation of a candidate bioabsorbable composite implant material with mechanical properties similar to bone. The composite studied was poly(ortho ester) reinforced with randomly-oriented, crystalline microfibers of calcium-sodium-metaphosphate. The component materials showed no acute cytotoxicity as determined by tissue culture agar overlay. Treating the microfibers with a diamine-silane coupling agent improved mechanical properties and slowed degradation in saline, but strength still decreased 50% in 1 week. When the composite material was then coated with a layer of matrix polymer alone it retained 70% of its strength and 70% of its stiffness after 4 weeks exposure to 7.4 pH Tris-buffered saline at body temperature. The marked improvement with the coating can be attributed to the hydrophobicity of poly(ortho esters).
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/jab.770030306
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  • 11
    Electronic Resource
    Electronic Resource
    Stability of a cyclically loaded hydroxyapatite coating: Effect of substrate material, surface preparation, and testing environment (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 3 (1992), S. 211-215 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Cyclic loaing of Ti-6-4 and Co-Cr-Mo (cast) test samples with grit-blasted or waffle-textured surfaces coated with a plasma-sprayed 50-μm HA layer was performed in air, Ringer's solution (5% dextrose), 0.9% NaCl (Tris buffer, pH 7.40), and balanced Hank's solution. Maximum interfacial stresses in bending of 40 ksi (280 MPa) and 20 ksi (140 MPa) were utilized, and the speciments tested to 106 cycles at 5 Hz with a MTS servohydraulic machine. Tested samples were examined by optical microscopy to determine coating integrity and thickness and by scanning electron microscopy (electron backscatter mode and EDAX) to determine surface morphology and chemical changes.The following observations were made: (1) Samples cyclically tested in solutions showed a general thinning of the coating, accentuated in the higher-stressed regions. (2) Samples tested with an equivalent static load in the solutions did not show this centralization. (3) Bare metal interface surfaces were noted on most of the edges of highly stressed central specimen regions, in several entire central regions, and on the upper surfaces of some of the waffled samples. (4) The specimens tested in Ringer's solution (pH 4.70 initially) demonstrated the most dramatic coating deterioration. (5) The coatings on titanium appeared more stable than these on Co-Cr as tested in all solution environments for both surface types.The HA coating evaluated in this experiment demonstrated increased instability when cyclically loaded in in vitro solutions of lowered pH and depleted cations (Ca2+) at stress levels of 280 MPa. The more physiological solution (Hank's) did not show this increased dissolution at the lower stress level. It is suggested that this type of testing be performed on other HA coatings due to the possible implications for long-term in vivo coating integrity.
    Additional Material: 5 Ill.
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    URL: http://dx.doi.org/10.1002/jab.770030308
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  • 12
    Electronic Resource
    Electronic Resource
    The bone-biomaterial interface. Davies, J. E. ed. Toronto: University of Toronto Press: 1991 (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 3 (1992), S. 237-238 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jab.770030312
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  • 13
    Electronic Resource
    Electronic Resource
    Clinical reviews: Mammary implants (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 3 (1992), S. 239-242 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jab.770030313
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  • 14
    Electronic Resource
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    Biomaterials education: An academic viewpoint (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 3 (1992), S. 231-236 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Biomaterials is emerging as an identifiable intellectual field of study. There are necessary preparatory studies to equip individuals to work within the field at various levels. The formal and informal instructional requirements are considered within the context of the academic program of the Department of Bioengineering at Clemson University, one of the first US university programs to focus on instruction and research in biomaterials.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/jab.770030311
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  • 15
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    Technical note: Embedded particulate contaminants in textured metal implant surfaces (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 3 (1992), S. 225-230 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Additional Material: 8 Ill.
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    URL: http://dx.doi.org/10.1002/jab.770030310
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  • 16
    Electronic Resource
    Electronic Resource
    Fabrication and characterization of an asymmetric polyurethane membrane for use as a wound dressing (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 3 (1992), S. 287-303 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: To prevent wound dehydration and bacterial penetration, a wound dressing should be occlusive, but on the other hand it should also be permeable for wound exudate to prevent bullae formation. To meet these requirements a new type of polyurethane wound dressing which consists of a microporous top layer (pore size 〈 0.7 μm) supported by a sublayer with a highly porous sponge-like structure containing micropores (pore size 〈10 μm) as well as macropores (pore size: 50-100 μm) was designed. The pores of both layers are interconnected and form a continuous structure in the membrane. Membranes according to this design were prepared either by means of a two-step or by means of a one-step casting process. Both fabrication methods are based on phase inversion techniques. Asymmetric polyurethane Biomer® membranes prepared by the two-step casting process were tested in vivo as full thickness skin substitutes using guinea pigs. Neither wound dehydration nor infections were observed while the drainage capacity of the wound dressing was effective in preventing bullae formation. Furthermore the wound dressing remained firmly adhered to the wound surface during the whole process of wound healing. In contrast to all other commercial wound dressings currently available the polyurethane wound dressing applied on excised clean wounds did not need to be replaced during healing but could be left on the wound until full regeneration of the skin had taken place after which it was spontaneously repelled. © 1992 John Wiley & Sons, Inc.
    Additional Material: 12 Ill.
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    URL: http://dx.doi.org/10.1002/jab.770030408
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  • 17
    Electronic Resource
    Electronic Resource
    Strain analysis of flexing blood pump diaphragms (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 3 (1992), S. 305-311 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Blood pumps usually use elastomer diaphragms that undergo repeated small-strain flexing (deformation). The stresses and strains that develop in the mechanically actuated diaphragms dictate the useful life and fluid-solid interactions of the diaphragm. A knowledge of these stresses and strains is essential for proper design of the pump's elastomer diaphragm. A nonlinear axisymmetric finite-element stress-strain analysis has been carried out on a Hexsyn rubber diaphragm used in a blood pump to illustrate a finite-element modeling technique. A situation involving the application of an axial deformation load on the diaphragm has been considered. In particular, the strains developed in a blood pump diaphragm during pumping have been quantified to illustrate the analysis technique. © 1992 John Wiley & Sons, Inc.
    Additional Material: 10 Ill.
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    URL: http://dx.doi.org/10.1002/jab.770030409
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  • 18
    Electronic Resource
    Electronic Resource
    Masthead (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 3 (1992) 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jab.770030101
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  • 19
    Electronic Resource
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    The effect of chain extenders and stabilizers on the in-vivo stability of polyurethanes (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 3 (1992), S. 17-22 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Poly(etherurethane) (PEU) and poly(etherurethaneurea) (Biomer®) films with and without antioxidant stabilizers were subcutaneously implanted into dogs and rats for up to 10 weeks. It was found that the molecular weight of the PEU films decreased over the 10-week period, while the Biomer® films increased in molecular weight. The presence of the stabilizers resulted in less severe changes in molecular weight. Surface cracking was most pronounced on both the stabilized and nonstabilized PEU films. Stress did not have to be applied to induce the surface cracking.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/jab.770030104
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  • 20
    Electronic Resource
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    An improved affinity support and immunoadsorbent with a synthetic blood group oligosaccharide and polymer coating for hemoperfusion (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 3 (1992), S. 9-15 
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    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: An improved affinity support and an immunoadsorbent suitable for extracorporeal perfusion of whole blood (or plasma) are reported. The affinity support consists of calcined diatomite-type silica particles to which a synthetic oligosaccharide hapten, viz. Atrisaccharide representing human blood group A, with a linking spacer-arm is chemically attached. The immunoadsorbent thus obtained is surface-modified with a polymer coating. The modified immunoadsorbent is not hemolytic and shows no loss of biological activity in reducing antibody titers in vitro. An important feature of the improved immunoadsorbent is that the polymer coating providesa better surface resistance and therefore stability to the affinity support to prevent the release of potentially harmful fines. The usefulness of a physically stable support as an affinity adsorbent for the selective removal of specific antibodies or unwanted substances directly from the blood circulation by extracorporeal immunoadsorption has profound medical significance because this would provide an efficient but safe and practical alternative to therapeutic intervention using plasma exchange or plasma perfusion, both of which require plasmapheresis.
    Additional Material: 2 Ill.
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    URL: http://dx.doi.org/10.1002/jab.770030103
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  • 21
    Electronic Resource
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    Customized neonatal incubator for measurement of platelet-artificial microvascular graft interactions under controlled flow, temperature, and transmural pressure (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 3 (1992), S. 1-7 
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    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A neonatal incubator has been custom modified to enable measurement of initial platelet retention on biomaterials in vitro under clinically relevant hemodynamic conditions. To calibrate this device, platelet retention on several materials having microconduit geometry (0.7-1.0 mm i.d.) has been measured after perfusion with citrated whole blood (containing 111 Indium-labelled platelets) at a shear rate of 312 s-1, 37°C, and 80 cm H2O transmural pressure. The relative reactivity of these materials toward platelets was: glass 〈 Fibrinogen(Fg)-coatedglass 〈 Fg-coated polyethylene 〈 polyethylene ∼ = Expanded polytetrafluoroethylene. Interindividual variation is relatively large (coefficient of variation = 35.5 ± 9.3%), but comparison to intraindividual controls reduces the variability to 14.8 ± 10.3%, a level which is suitable for economical testing of platelet retention to biomaterials in the presence or absence of drugs. This approach may have particular value in the study of the mechanism of platelet interactions with artificial microvascular grafts under perfusion conditions which are relevant to the first moments of flow, when initial platelet deposition occurs.
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    URL: http://dx.doi.org/10.1002/jab.770030102
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  • 22
    Electronic Resource
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    Controlled release of bisphosphonate from a biodegradable implant: Evaluation of release kinetics and anticalcification effect (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 3 (1992), S. 23-28 
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    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The present investigation describes the formulation and the in vivo efficacy of prolonged controlled-release chitosan matrices, containing the novel anticalcification agents adipoyland suberoylbisphosphonate (AdBP and SuBP). Chitosan matrices were prepared by the solvent-cast method and the role of several factors such as polymer molecular weight (MW), crosslinking, and drug load concentration, on the release rate profile have been examined. Crosslinking of chitosan films retarded degradation rate of the polymer but not the release rate of the embedded drug. Chitosan's MW and drug load concentration did not affect drug release rate. The release kinetics of the bisacylphosphonates were characterized by initial burst-effect and pseudo zero-order kinetics in the following release phase. AdBP/chitosan matrices (co-implanted subdermally in rats with the calcifiable bioprosthetic heart valve tissue) significantly inhibited tissue calcification after 15 and 30 days implantation (66.4 and 108.6 μg/mg Ca++ in comparison to 2.7 and 3.6 μg/mg Ca++, untreated and treated groups, respectively). No side effects were noted.
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    URL: http://dx.doi.org/10.1002/jab.770030105
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  • 23
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    RF plasma treatment of metallic implant surfaces (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 3 (1992), S. 39-44 
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    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Radio-frequency air plasma treatments of Ti-6-4 and Co-Cr implants increased surface wettability but concurrently increased ionic release. In vitro tissue culture experiments demonstrated no enhancement of cell growth and enrichment. Short-term rabbit tibial implants also showed no difference between treated and untreated implants.
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    URL: http://dx.doi.org/10.1002/jab.770030107
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    Vibrational response analysis: Non-destructive evaluation of ingrowth into porous coated implants (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 3 (1992), S. 29-38 
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    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Quantitative methods of evaluating ingrowth into porous coated implants have traditionally involved destructive mechanical testing. In this study, it was hypothesized that the response to a vibrational stimulus could estimate the shear strength at the bone-implant interface as measured by pushout. A derived model predicts that the square of the frequency at resonance is linearly related to this interfacial strength. It was further hypothesized that the level of vibration required for a meaningful response would not be destructive. This study was done using nonloaded, porous coated cylindrical implants which were press fit in the distal femora of dogs. Femora were harvested at 2, 4, and 6 weeks postimplantation. The implants were sectioned into 4-mm slices and then evaluated by vibration, pushout, and light microscopy. Vibrational response analysis was conducted with broad band random excitation using Fast Fourier transform signal analysis. Pushout values were obtained using a materials testing machine. The resulting correlation was statistically significant (F = 201, r2 = 0.90, p 〈 10-6). Light microscopic evaluation of vibrated samples showed no difference at the bone-implant interface when compared to controls.
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    Glass-Ceramic implant in acetabular bone defect: An experimental study (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 3 (1992), S. 245-249 
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    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Extensive acetabular defects produced surgically in 25 dogs were repaired using A - W glass-ceramic blocks. No dislocation of the femoral head, and no displacement or breakdown of the blocks was seen 1 year after surgery. All dogs were able to run normally shortly after surgery, except for one that limped for a short time. The failure load between the blocks and the bone had increased markedly 2 months after implantation. The failure load/unit area was 33.2 kgw/cm2 1 year after implantation. We conclude that glass-ceramic supplementation of the acetabulum is successful experimentally, and that this may be a promising method for repair of large acetabular bone defects. © 1992 John Wiley & Sons, Inc.
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    The effect of a TCP-collagen implant on the healing of articular cartilage defects in the rabbit knee joint (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 3 (1992), S. 251-258 
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    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Osteochondral defects in the rabbit knee were filled with a TCP-collagen mixture. In the femoral condyles a fibrous tissue was formed in the defects similar to that seen in control defects. In the tibial plateau defects were made with penetration of the underlying epiphysis. Repair tissue was formed resembling articular cartilage. © 1992 John Wiley & Sons, Inc.
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    The effect of egg phosphatidylcholine on antibiotics retention and release from hydroxyapatite (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 3 (1992), S. 269-273 
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    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Hydroxyapatite (HAP) has been used in orthopedics as an aid in bone grafts following surgery of bone tumors and osteoarthrosis, often promoting osteoconduction. The incorporation of antibiotics into HAP beads to prevent local infection would seem to be therapeutically effective. This report describes in vitro and in vivo release rate of cefotiam hydrochloride (CTM, 3.5 mg/bead) loaded into HAP beads (8.48 mm in diameter). Egg phosphatidylcholine (EPC) was also incorporated into HAP to control the rate of release of CTM. In vitro, 100% of CTM was released within 3 h from the EPC-free HAP beads. The rate of diffusion of CTM from HAP was prlonged with the incorporation of EPC. In vivo, 100% of CTM of the EPC-free CTM was released within 7 h but the rate of release of CTM from the EPC-CTM was extended. In vivo, the serum level of CTM reflected the rate of release of the antibiotics from the HAP bead. We conclude that EPC is useful in controlling the diffusion rate of CTM from HAP. © 1992 John Wiley & Sons, Inc.
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    Osteoconduction of bioceramics in normal and osteopenic rats: Comparison between bioactive and bioinert ceramics (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 3 (1992), S. 259-268 
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    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Rats with experimental osteopenia, which was induced by resecting both ovaries and sciatic nerves (OVX + NX), were used to evaluate osteoconduction of an apatite and wollastonite-containing glass-ceramic (designated A-W.GC) and an alumina ceramic. The bone mineral densities (BMDs) of the femurs were measured by dural energy X-ray absorptiometry (DEXA) and determination of the ash weight. Twelve weeks after the first operation, when the BMDs in the OVX + NX groups were about 20% less than that in the sham-treated groups (Sham), the bioceramics were implanted into the proximal tibiae. The bone mineral masses around the implants in the proximal tibiae were evaluated by histological examination of undecalcified specimens and DEXA. Both types of implants in the OVX + NX groups showed less reactive bone than those in the Sham groups. However, a histomorphological study revealed that the direct contact area between bone and implant was larger with bioactive ceramic A-W.GC than with the bioinert alumina ceramic even under osteopenic conditions while two types of ceramic made no difference on the bone at distance from the implant. The direct contact area with A-W.GC did not show any difference between the Sham and the osteopenic OVX + NX groups. The bioactive ceramic A-W.GC appears to have good osteoconductivity solely on its surface even under osteopenic conditions.
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    The surface treatment of polypropylene molds and its effect on the quality of cast contact lenses (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 3 (1992), S. 275-279 
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    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: An investigation of the surface by XPS photoelectron spectroscopy has shown that the process of production of cast contact lenses based on poly(2-hydroxyethyl methacrylateco-diethyleneglycol methacrylate) is accompanied by mass transfer at the lens-mold boundary. This phenomenon, which impairs the compatibility of the lens during its application, can be considerably suppressed by employing a suitable surface modification of polypropylene molds. The surface treatment consisting in the oxidation of the mold surface by an AC corona discharge in the oxygen atmosphere increased hydrophilicity of the material, thus facilitating separation of the lens from the mold. The results of the XPS study were also confirmed microscopically by employing the SEM method. © 1992 John Wiley & Sons, Inc.
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    URL: http://dx.doi.org/10.1002/jab.770030406
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    Technical note: A convenient testing template (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 3 (1992), S. 313-313 
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    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jab.770030410
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    A versatile alginate droplet generator applicable for microencapsulation of pancreatic islets (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 3 (1992), S. 281-286 
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    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Alginate beads for immunoisolation of pancreatic islets by microencapsulation should be small, smooth, and spherical in order to ensure that around the islets a strong alginate-polylysine-alginate capsule will be formed with optimal biocompatibility and diffusion of nutrients and hormones. However, the preparation of small capsules around islets is difficult. Our newly designed air jet droplet generator allows for variations in the length and diameter of the alginate nozzle and the air jacket and is in this way adaptable to a required bead size. Alginate droplets are converted into rigid beads in a 100 mM CaCl2 solution. Their size depends upon the diameter of the jacket, the air flow rate, and the outer diameter of the nozzle, whereas the production rate depends upon the pressure on the alginate, and on the diameter and the length of the nozzle. When the air flow or the alginate flow surpasses a certain rate, the droplets are fragmented. Thus study describes the mutual relationship of these variables and defines their optimal range for reproducible production of smooth and spherical beads for microencapsulation of islets at an acceptable production rate. © 1992 John Wiley & Sons, Inc.
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    Histological techniques for the study of the biomaterial-tissue interface of total joint replacements  -  a modification for the preservation of bone cement (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 3 (1992), S. 59-62 
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    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The methods usually employed for the histological processing of orthopaedic specimens of cemented joint arthroplasties involve treatment with methacrylate monomer and organic solvents which dissolve the polymethylmethacrylate cement. This may distort the intimate relationship of the cell layers along the surface of the interface between the bone and the cemented implant. The authors report on a technique for the processing and embedding of cemented orthopaedic implants which permits preservation of the polymethylmethacrylate cement. The method utilizes a modification of Spurr's low viscosity epoxy resin and avoids the use of solvents such as acetone. Undecalcified sections of cemented joint replacements from animal studies and human specimens have been prepared using this method. It is possible to use these sections for detailed histomorphologic and histomorphometric analysis of bone tissue and of the soft tissue membrane adjacent to the polymethylmethacrylate cement.
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    Plasma surface modification of synthetic absorbable sutures (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 3 (1992), S. 131-146 
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    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The aim of the study was to examine the feasibility of using plasma surface modification technology to alter the hydrolytic degradation rate of commercial synthetic absorbable sutures. Size 2-0 Dexon, Vicryl, PDSII, and Maxon sutures were tested. They were treated by two different surface modification techniques: parylene deposition and plasma gases (Methane, trimethylsilane, and tetrafluoroethene). The thickness of surface treatment ranges from 200 to 1000°AR. The treated sutures were subject to in vitro hydrolytic degradation in phosphate buffer of pH = 7.4 at 37°C for up to 120 days. The tensile breaking strength, weight loss, surface wettability, bending stiffness, and surface morphology were evaluated. The results indicated that the concept of plasma surface treatment for altering the hydrolytic degradation of synthetic absorbable sutures was feasible, and the level of improvement depended on the type of sutures, the treatment conditions, and the duration of hydrolysis. Vicryl and PDSII sutures showed overall the best improvement in tensile strength retention among the four commercial sutures. Dexon and Maxon sutures, however, exhibited only marginal improvement. The observed improvement in tensile strength retention appeared to be related to the increasing hydrophobicity of the sutures. The surface treatments did not adversely affect the bending stiffness of the sutures and no visible surface morphological changes were observed. Refinements and optimization of the surface treatment conditions are needed for achieving the maximum advantage of the proposed concept, particularly shielding the harmful effect of uv during plasma treatment.
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    Letter to the Editor (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 3 (1992), S. 165-165 
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    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jab.770030213
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    A silver-sulfadiazine-impregnated synthetic wound dressing composed of poly-l-leucine spongy matrix: An evaluation of clinical cases (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 3 (1992), S. 153-161 
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    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The management of severe burns requires the suppression of bacterial growth, particularly when eschar and damaged tissue are present. For such cases, silver sulfadiazine (AgSD) cream has been traditionally applied. This antibacterial cream, however, cannot be used in conjunction with a temporary wound dressing that is needed to promote healing. The authors developed a synthetic wound dressing with drug deliver capability for clinical use by impregnating a poly-- spongy matrix with AgSD, which is released in a controlled, sustained fashion. In general, the dressing adhered firmly to the wound in the case of superficial second-degree burns, and during the healing process it separated spontaneously from the re-epithelialized surface. In the management of deep second-degree burns where eschar and damaged tissue were present, the dressing had to be changed at intervals of 3 to 5 days until it adhered firmly to the wound. Once the dressing had firmly attached to the wound, it was left in place until it separated spontaneously from the re-epithelialized surface. Dressing changes were fewer than with other treatments and the pain was effectively reduced. Cleansed wounds were effectively protected from bacterial contamination. Of 52 cases treated with this wound dressing, 93% (14/15) of superficial second-degree burns, 75% (3/4) of deep second-degree burns, 85% (6/7) of superficial and deep second-degree burns, and 75% (12/16) of split-thickness skin donor sites were evaluated as achieving good or excellent results.
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    Masthead (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 3 (1992) 
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    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
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    URL: http://dx.doi.org/10.1002/jab.770030301
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    Announcement (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 3 (1992), S. 243-243 
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    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
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    URL: http://dx.doi.org/10.1002/jab.770030314
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    Masthead (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 3 (1992) 
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    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    URL: http://dx.doi.org/10.1002/jab.770030401
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    The editor's corner (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 3 (1992), S. 315-316 
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    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    URL: http://dx.doi.org/10.1002/jab.770030411
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    Letters to the editor (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 3 (1992), S. 75-75 
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    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jab.770030113
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    Bioabsorbable polymers update (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 3 (1992), S. 73-74 
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    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jab.770030112
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    Masthead (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 3 (1992) 
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    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jab.770030201
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    Research and development report: Production of fine particulate ultra high molecular weight poly(ethylene) for biological response studies (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 3 (1992), S. 77-80 
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    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Interest in biological responses to particulate biomaterials has produced a need for well-characterized submicron ultra high molecular weight poly(ethylene) (UHMWPE) debris. A new technique, cryogenic attrition, is described as well as a characterization of an initial ca. 65% submicron preparation of UHMWPE, termed grind S. Production of submicron particles from a common commercial medical grade of primary UHMWPE “grain” produces fractions with different densities, apparently reflecting the presence of crystalline and amorphous phases. Further process optimization and debris characterization is planned with eventual distribution of material as an interlaboratory comparison material for biological response experiments.
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    Pulsed laser deposition of hydroxylapatite thin films on Ti-6Al-4V (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 3 (1992), S. 87-93 
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    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Pulsed laser deposition was used to deposit thin films of calcium hydroxylapatite (Ca10(PO4)6(OH)2), or HA, on polished substrates of Ti-6Al-4V. Thin films of pure, crystalline HA, uncontaminated by other calcium phosphate phases, were deposited over a range of temperatures between 400 and 800°C. The HA films were polycrystalline with a preferred (001) crystallographic orientation, as determined by transmission electron microscopy and x-ray diffraction. Adhesion of the HA films to the Ti-6Al-4V substrates was excellent when films were deposited at temperatures ≤600°C; in a scratch test, mean pressures of ca. 1010 Nm-2 produced conformational cracking in a film deposited at 600°C, but no decohesion from the substrates.
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    The effect of the addition of methylene blue on the fatigue strength of simplex P bone-cementSupported by the William H. Harris Foundation, Boston, MA 02114. (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 3 (1992), S. 81-85 
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    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: To aid in cement removal during revision arthroplasty, it has been proposed to add methylene blue to bone cement to provide contrast between the cement and bone. However, it is essential that the fatigue strength of the cement not be reduced by the addition of the methylene blue. The effect of adding 1 mL of an aqueous 1% solution of methylene blue to one pack of Simplex P prepared in the standard fashion (uncentrifuged) was studied. We also measured the fatigue properties of centrifuged Simplex P with three different methylene blue preparations. We studied adding 1 mL of an aqueous 1% solution of methylene blue, 0.5 g of methylene blue powder, and 0.1 mL of a 10% solution of methylene blue per pack of Simplex P bone cement. Adding 1 mL of a 1% methylene blue solution to 40 g of Simplex P without centrifuging the cement after mixing produced a cement with a mean fatigue life comparable to the uncentrifuged Simplex P without the methylene blue. However, the fatigue data scatter was higher for the uncentrifuged methylene blue preparation. The optimum methylene blue impregnated cement preparation was produced by adding 1 mL of a 1% methylene blue solution to 40 g of Simplex P powder, mixing with chilled monomer, and centrifuging for 60 s. Sterile 1 mL vials of 1% methylene blue solution are available in the operating room. Thus the experienced surgeon can use a cement containing color to facilitate distinguishing cement from bone in cases needing revisions without weakening the cement.
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    In vitro analysis of the effects of biomaterial adherence on a Staphylococcus epidermidis strain's sensitivity to cephaloridine (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 3 (1992), S. 95-98 
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    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: This study examined the effects biomaterial adherence had on Staphylococcus epidermidis-46 morphology and sensitivity to the antibiotic cephaloridine. Polymethylmethacrylate (PMMA) discs served as the biomaterial substratum in this study. Suspension cultures of SE-46 at 108 CFU/mL were allowed to adhere to PMMA discs for 2, 6, or 12 h prior to exposure to cephaloridine at 250 μg/mL, which is 500 times greater than the MIC of 0.5 μg/mL. After a 24-h exposure to the antibiotic viable bacteria adherent to the disc were removed and counted. Those data revealed that at shorter adherence times a larger percentage of the adherent organism were erradicated by antibiotic exposure, 83.6%versus 15.6%for 2-h and 12-h adherencetimes, respectively. Although a significant percent of the organisms were killed with short adherence times, the organism still persisted in the face of high concentrations of cephaloridine. Scanning electron micrographs of organism adherent for 2 and 12 h revealed distinct morphological changes in the extracellular matrix indicating increased matrix production with longer adherence. Thus, these data reveal that adherence to biomaterials provides a protected environment for the bacteria and the time an organism is adherent to a biomaterial surface prior to antibiotic exposure can also increase the organism's resistance to antibiotics.
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    Polypropylene IUCD retrieval fibers: Surface morphology, material properties, microbial attachment, and migration (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 3 (1992), S. 99-115 
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    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Highly drawn and oriented polypropylene fibers used for the retrieval thread of the Cu-7 intrauterine contraceptive device (IUCD) are compared as to surface morphology and crystallinity with polypropylene fibers prepared under different conditions. A series of experiments also demonstrates the colonization of the surface of polyolefin fibers by pathogenic bacteria that are often found in the human vagina. Moreover, it is demonstrated that the retrieval threads appear to encourage pathogenic bacteria to migrate across the surface of agar. The results also indicate that control of drawing and annealing can avoid the surface fibrillation and tendency to fail by separation into a bundle of multifilaments that are observed with the IUCD retrieval threads.
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    Burst testing of condoms. I. Basic features of the force-deformation curve of latex-rubber condoms (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 3 (1992), S. 117-122 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Inflation of a rubber condom involves biaxial deformation of the material which can be modeled by the use of an appropriate strain-energy function. Force versus deformation data for uniaxial extension of strips of condoms were used to determine the parameters for Ogden's form of a strain-energy function. These parameters were then used to fit experimentally obtained burst test data to a stress-strain equation formulated for inflation of condoms in a burst test. Experimental data on inflation of condoms agree well with theoretical curves verifying the applicability of the biaxial stress-strain equation to the particular strain-energy function on which it is based.
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    Bioactive ceramics for periodontal treatment: Comparative studies in the patus monkey (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 3 (1992), S. 123-129 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Four bioactive ceramic materials currently recommended for regeneration of osseous tissues in treatment of periodontal disease have been compared with Bioglass® particulates, of equivalent size in two compositions, in a monkey model. Both Bioglass® materials were found to be easily manipulated, were haemostatic and osteoproductive allowing restoration of both alveolar bone and periodontal ligament. Epithelial downgrowth was inhibited and epithelial attachment was close to the preimplantation level. The other materials were slower to act and epithelial downgrowth was to the same level as in unfilled control defects.
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    The editor's corner: Implant retrieval and analysis revisited (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 3 (1992), S. 163-163 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jab.770030212
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    A method to determine shear adhesive strength of fibrin sealants (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Biomaterials 3 (1992), S. 147-151 
    Details
    ISSN: 1045-4861
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The adhesive strength of fibrin sealants has not been rigorously evaluated to date. The adhesive strength of six different concentrations of cryoprecipitated fibrinogen as well as the commercially available fibrin tissue adhesive Tissucol® was tested under controlled conditions utilizing split-thickness skin grafts as the test adherand. This test configuration permitted the modeling of bonding strength for attachment of skin grafts as well as incorporate established engineering test standards for adhesives. An increase in fibrin concentration corresponded with an increase in shear adhesive strength. No significant increases in adhesive strength were attained after 5 min of bonding for all tested concentrations, except for the commercial adhesive, which attained the adhesive strength of an equivalent concentration of cryoprecipitated adhesive after 90 min. The adhesive strength, however, was an order of magnitude less than reported values of the tensile strength of fibrin material for similar concentrations. Therefore, it is important that the surgeon use a sufficiently high fibrinogen concentration for the specific clinical indication. The method of fibrin sealant preparation and/or the compounding adjuncts appear to have an effect on the development of adhesive strength.
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    Masthead (1992)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 26 (1992) 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820260101
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    Tensile strength of the interface between hydroxyapatite and bone (1992)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 26 (1992), S. 7-18 
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    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Tensile strength of the interface between hydroxyapatite (HA) and bone was tested. Scanning electron microscopy was used to observe the tensile failure mode and the morphological change of hydroxyapatite ceramic surface in bone. The porosity of hydroxyapatite is 14% and pore size less than 2 μm. After 2 weeks of implantation, the tensile strength of the interface is 0.72 MPa. After 4, 8, and 16 weeks, the average tensile strength stayed at 1.5 MPa. SEM showed that tensile failure occurred at the HA-bone interface at the second week, but after 4 weeks, the failure occurred between HA particles within the bulk, and not at the HA-bone interface. Calcified tissue was directly deposited on the HA ceramic surface and exits also in the micropores. Near the interface, sintered necks among HA ceramic particles were subjected to biodegradation.
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    The effect of phase differences on the time-dependent variation of the zeta potential of hydroxyapatite (1992)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 26 (1992), S. 147-168 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The osteoconductive nature of calcium phosphate ceramics (CPC) follows from several proven effects, such as a direct bone attachment and enhanced bone tissue formation. Mechanisms leading to these phenomena are still largely undiscovered. Specifically, little is known about the CPC surface and cell-driven reactions. These atomic and molecular level events are involved in tissue attachment and enhanced tissue formation. It is hypothesized that the zeta potential of these ceramics is directly related to the surface reactivity governing osteoconductivity. As a first step in our analysis, the zeta potential of stoichiometric and Ca-deficient hydroxyapatite was determined as a function of immersion time. It is concluded that, under the conditions of the experiment, the observations support the hypothesis in a dual way. First, the absolute values of the zeta potential which were measured are related to electrokinetic potentials known to cause substantial effect on the cellular activities and bone tissue formation when applied exogenously. Second, the magnitude and duration of the changes in zeta potential are related to an ion exchange between the hydrated layer around the ceramic and the ceramic surface, and a net precipitation of new material. If these findings could be confirmed in other solutions, i.e., solutions with a substantially equivalent composition as the fluids in developing bone tissue, a basis would be provided to explain the bridging of the ceramic surface with the surrounding developing tissue.
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    Evaluation of metallic personalized hemiarthroplasty: A canine patellofemoral model (1992)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 26 (1992), S. 239-254 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The purpose of this study was to characterize the response of articular cartilage to weight bearing against a metallic personalized hemiarthroplasty prosthesis. Ten dogs each underwent surgery in which an elastomeric replica of the left femoral patellar groove was made. Using this replica, a 0.5-mm-thick prosthesis was cast in Co-Cr alloy and subsequently the surface was polished to a mirror finish which had a center line average roughness value in the range of human hemiarthroplasty implants. A second surgery was performed to resurface the left trochlea with this prosthesis. Five animals were sacrificed at 3 months and 5 at 6 months. Cartilage damage occurred primarily in the distal region of the patella, and was especially evident at 6 months. Mechanical indentation tests conducted on patellar cartilage in a saline bath at 37°C indicated both increased deformation and residual deformation in the affected areas, indicative of degenerative change. Areas of fibrillation with a depletion of proteoglycans were identified histologically. These areas were only superficial at 3 months but became more extensive at 6 months. Rheological analysis of the synovial fluid of tests joints indicated that a decrease in viscosity occurred from 3 to 6 months, an additional indicator of progressive degeneration. This novel implant model showed that even if a metallic hemiarthroplasty implant had an identical geometry as the joint surface being replaced and had a reasonably smooth surface, cartilage degeneration inevitably resulted.
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    Differences in ceramic-bone interface between surface-active ceramics and resorbable ceramics: A study by scanning and transmission electron microscopy (1992)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 26 (1992), S. 255-267 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The interface between bioactive ceramics and bone was studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The materials were apatite-wollastonite-containing glass ceramic (A-W · GC) as a representative surface-active ceramic, and calcite and p-tricalcium phosphate (p-TCP) as resorbable ceramics. Particles of these materials, ranging between about 100 pm and 300 pm in diameter, were implanted into rat tibiae, and specimens were prepared for observation at 8 weeks after implantation. Both SEM and TEM demonstrated that A-W · GC was bonded t o bone through a thin Ca-P-rich layer consisting of fine apatite crystals apparently different from those of bone in shape, size, and orientation. Collagen fibers of the bone reached the surface of this layer, and chemical bonding between A-W · GC and the bone was speculated. Calcite and p- TCP, on the other hand, made direct contact with the bone, and no apatite layer was present at the interface. The surfaces of the implants became rough due to degradation, and bone grew into the finest surface irregularities. However, we were unable to demonstrate any continuity of crystals between the resorbable implants and bone by high-resolution TEM. Ac- cordingly, the bonding strength was considered to be mainly attributable to mechanical interlocking.
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    The mechanisms of passive dissolution of titanium in a model physiological environment (1992)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 26 (1992), S. 319-338 
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    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The surface chemistry, oxidation, and dissolution kinetics of titanium were measured to establish the mechanisms of passive dissolution in physiological environments. Titanium thin films were immersed in 8.0 mM ethylenediamine- tetraacetic acid in simulated interstitial electrolyte (EDTA/SIE) and maintained at 37°C, 10% O2, 5% CO2 and 7.2 pH for periods of time up to 3200 h (133 days). Two immersion schemes were employed: the integral sequentially determined the titanium released into a solution of accumulated dissolution products; and the differential continuously replenished the test solution. The solutions were analyzed for titanium by electrothermal atomic absorption spectrometry (EAAS), and the sample surfaces were analyzed by Auger electron spectroscopy (AES) and x-ray photoelectron spectroscopy (XPS) to determine oxide composition, stoichiometry, and thickness. Prior to immersion two types of hydroxyl (OH) groups were distinguished on the TiO2 surface. Upon immersion, the chemistry of the surface changed as a function of immersion: the presence of OH groups increased and P (nonelemental) was detected at the surface. The dissolution kinetics obeyed a two-phase logarithmic model, where the transition between phases occurred simultaneously with the adsorption of the P-containing species. The dissolution kinetics depended on surface reactions, electric field strength, and molecular diffusion. These mechanisms explain the observed dependence of dissolution kinetics on the properties of the surface oxide and solution ligands.
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    Masthead (1992)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 26 (1992) 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820260401
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    Protein adsorption of biomedical polymers influences activated monocytes to produce fibroblast stimulating factors (1992)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 26 (1992), S. 457-465 
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    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The studies presented in this manuscript were based upon the hypothesis that monocytes/macrophages selectively produce cytokines and growth factors due to their interactions with polymers and proteins which are adsorbed to their surfaces. These factors in turn selectively influence the ability of fibroblasts to proliferate. The factors which influence fibroblast proliferation were released from monocytes incubated with polymers: Biomer®, polydimethylsiloxane (PDMS), polyethylene (PE), expanded polytetrafluoroethylene (ePTFE), Dacron, and control polystyrene with and without preadsorption with physiological concentrations of IgG, fibrinogen, fibronectin, hemoglobin, or albumin. No simple correlation was found between adsorbed protein, biomedical polymer, and the ability monocytes to produce growth factors and cytokines which influence fibroblast proliferation. This is evidence for selective protein-polymer interactions which turn selectively activate monocytes produce variable cell cycle competence and progression factors controlling fibroblast growth.
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    Human gingival tissue response to HTR polymer (1992)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 26 (1992), S. 517-527 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Biopsies secured during reentry surgical evaluation of previously treated periodontal osseous defects were examined for gingival tissue response to HTR polymer. Eleven patients provided biopsies of HTR grafted sites 6-7 months after initial implantation. Minimal inflammation and infrequent foreign body giant cells were found. Bone was present in about half of the samples and osteogenesis associated with the HTR graft material was seen in about 20% of the biopsies. Serendipitously, biopsies of other graft materials or debridement only sites from 6-30 months post-treatment were also available for analysis and comparison, and showed similar tissue response. The results of this study suggest that HTR polymer (and other graft materials) is very biocompatible and elicits no untoward gingival tissue responses when placed in periodontal osseous defects.
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    Biotinylation of implantable collagen for drug delivery (1992)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 26 (1992), S. 547-553 
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    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
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    URL: http://dx.doi.org/10.1002/jbm.820260410
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    Cytokine and growth factor production by monocytes/macrophages on protein preadsorbed polymers (1992)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 26 (1992), S. 837-850 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: These studies evaluate the effect of biomedical polymers: Biomer, polydimethylsiloxane (PDMS), polyethylene, expanded polytetraf luoroethylene (ePTFE), Dacron, and the control polystyrene with or without adsorbed proteins IgG, fibrinogen, and fibronectin on the ability of activated human monocytes/macrophages to produce Interleukin 1 Beta (IL-1-B), Interleukin 6 (IL-6), and Tumor Necrosis Factor Alpha (TNF-A). Monocytes/macrophages incubated on biomedical polymers with or without protein preadsorption produce variable levels of IL-1-B, IL-6, and TNF-A dependent on the polymer and adsorbed protein. IL-6 was produced in the greatest quantity and was the most influenced by protein adsorption. ePTFE and PDMS polymers were least stimulating while polystyrene was the most stimulating of monocyte activity. Adsorbed IgG consistently altered the ability of the polymers to activate monocytes/macrophages to produce cytokines. These studies provide important insight into conditions which modulate monocyte/macrophage activity in response to protein preadsorbed biomedical polymers.
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    Bone induction by demineralized bone particles: Long-term observations of the implant-connective tissue interface (1992)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 26 (1992), S. 897-913 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Allogeneic demineralized bone (DB) powder was applied to subcutaneous pockets and cranial defects of rats and histological, histomorphometrical, and radiological evaluation was performed one to 52 weeks after implantation. In both type of implants cartilage formation was observed after 1 week between DB particles and in former vascular channels and crevices within the particles. Foci of bone formation were observed after 2 weeks in the center of the implant. Remineralization of DB particles only occurred in close contact with the new bone tissue by which they became incorporated, indicating that remineralization of DB is a continuation of a process which has started in live bone. At all times, the interface between implant and connective tissue of the host consisted of a layer of nonremineralized DB particles embedded in fibrous connective tissue. This rim was thinner at the dura-mater-side in the cranial implants, compared with the skin-side of the same implants as well as all sides of the subcutaneous implants. The rim became thinner with time but never disappeared completely. The outer contour of the mineralized implant sometimes ran right through a DB particle. A critical concentration of bone-inducing agent leaking from DB particles seems to be necessary for bone induction. We suggest that at the interface of the implant and loose connective tissue this concentration is never reached, which results in maintenance of the rim.
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    Development and use of a parallel-plate flow chamber for studying cellular adhesion to solid surfaces (1992)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 26 (1992), S. 725-738 
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    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A parallel-plate flow chamber is developed in order to study cellular adhesion phenomena. An image analysis system is used to observe individual cells exposed to flow in situ and to determine area, perimeter, and shape of these cells as a function of time and shear stress. With this flow system the behavior of human fibroblasts spread on glass is studied when exposed to an increasing laminar flow. The flow system appears to be well-suited for following individual cells during detachment. After 75 to 90 min, at a shear stress of 350 dynes/cm2, more than 50% of the spread cells are detached from the surface. Cells with higher spreading areas stay longer at the glass surface. Cells round up before detaching. Sometimes the cell body is attached to the substratum through a thin filament during detachment. At the scanning electron microscopy level numerous filopodial extensions are observed. Cell material could only rarely be observed at the light or scanning electron microscopic level on the substratum once a cell was detached.
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    Reduction of fibrinogen adsorption on PEG-coated polystyrene surfaces (1992)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 26 (1992), S. 779-790 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Reduction of protein adsorption by coating surfaces with polyethylene glycol (PEG) is well documented. The present work has four goals related to these previous studies: first, to develop chemistry providing densely packed, covalently bound PEG on polystyrene (PS); second, to determine the ability of these modified surfaces to reject fibrinogen; third, to compare the protein-rejecting ability of branched and linear PEGs; and fourth, to examine the utility of an ELISA-type procedure for measuring protein adsorption. It was found that PEG-epoxide could be readily coupled to amine groups of poly(ethy1ene imine) (PEI), which had been preadsorbed onto an oxidized PS surface. The PEG groups on branched PEGs appear to act as an excluded volume to repel proteins, similar to arguments previously raised for linear PEGs. The results of protein adsorption studies showed that fibrinogen adsorption is significantly reduced by coating polystyrene with either linear or branched PEGs of 1500 to 20,000 in molecular weight. The ELISA technique was found to be equivalent in sensitivity to radiolabeled fibrinogen for estimating adsorption levels. It is expected that PEG-coated PS will have much utility in a variety of biomedical applications.
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    Letter to the Editor (1992)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 26 (1992), S. 833-833 
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    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820260613
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    Masthead (1992)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 26 (1992) 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820260701
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    Decreased tissue reaction to bioprosthetic heart valve material after L-glutamic acid treatment. A morphological study (1992)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 26 (1992), S. 1231-1240 
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    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Degenerative alterations of two different glutaraldehyde (GA)-fixed bioprosthetic heart valve materials were investigated in subcutaneous rat implants: Bovine pericardium, prepared according to clinically used bioprosthetic heart valve material (BHV) was compared to alternatively preserved pericardium (APHV), which was fixed in GA and treated with L-glutamic acid. Following 63 days of subcutaneous implantation, calcification of APHV implants was significantly lower as compared to BHV implants (13 ± 6 versus 158 ± 18 μg Ca/mg dry weight tissue; p ± 0.05). In BHV implants ultrastructural investigations showed nucleation of plate-shaped hydroxyapatite crystals at the surface of collagen fibrils and in remnants of connective tissue cells; no signs of calcification could be detected in APHV implants. The time-course of the inflammatory reaction was determined by quantification of immunohistochemical stained mononuclear host-cells invading the implants. In both preparation groups inflammatory reaction reached maximum 42 days after implantation. However, infiltration rate of inflammatory cells was markedly decreased in APHVs as compared to BHVs (p ≤ 0.05). © 1992 John Wiley & Sons, Inc.
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    Evaluation of hydroxylapatite/poly(l-lactide) composites: Mechanical behavior (1992)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 26 (1992), S. 1277-1296 
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    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: By mixing hydroxylapatite (HA) into L(-) dilactide monomer, prior to polymerization to poly(L-lactide) (PLLA), hydroxylapatite filled poly(L-lactide) composites were obtained. This study reports about the mechanical properties of these composites compared with unfilled PLLA. It was concluded that a 30 wt% HA/PLLA composite has better compressive and tensile strengths, higher stiffness and Vickers hardness number than unfilled PLLA (Mv: 125-150,000). Gas sterilization (ethylene oxide) affects molecular weight and flexural strength significantly. Implantation studies revealed loss of 50% of initial flexural strength within 3 weeks, and a faster decline of flexural strength was observed in phosphate buffered saline than in the subcutis of goats. From a mechanical point of view storage at -20°C proved to be a safe method. In its current state HA/PLLA composites can not be used as implant materials that have to resist major forces. However, such composites might be useful in nonloadbearing applications in orthopedic or maxillofacial surgery. © 1992 John Wiley & Sons, Inc.
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    Effect of surface processing on the attachment, orientation, and proliferation of human gingival fibroblasts on titanium (1992)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 26 (1992), S. 1325-1341 
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    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The adhesion, orientation, and proliferation of human gingival fibroblasts was studied on electropolished (elpTi), etched etchTi, and sandblasted (sblTi) titanium surfaces. The texture, chemical state, and composition of the titanium surfaces were analyzed using a surface tracing instrument and electron spectroscopy for chemical analysis. Considerable differences were evident in the surface texture and chemical composition of the differently treated titanium plates. Electropolishing produced the smoothest and cleanest surface. Human gingival fibroblasts attached, spread, and proliferated on all titanium surfaces. However, cells on elpTi exhibited an extremely flat morphology and seemed to form cellular bridges with adjacent cells, whereas the etchTi and sblTi surfaces harbored both round and flat cells with many long processes. Cells on elpTi appeared to grow in thick layers with no specific orientation, whereas on etchTi surfaces they were migrating along the parallel, irregular minor grooves caused by mechanical polishing, and on sblTi surfaces they seemed to grow in clusters. Stress-fiber type actin bundles and vinculin-containing focal adhesions were present in cells spreading on elpTi and etchTi surfaces but not in cells spreading on sblTi surfaces. Cell shape, orientation, and proliferation appear to depend on the texture of the titanium surface and probably also on the properties of the oxide layer and adjacent bulk material. Our findings suggest that smooth or finely grooved titanium surfaces could be optimal in implants adjacent to soft tissues as they support the attachment and growth of human gingival fibroblasts. © 1992 John Wiley & Sons, Inc.
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    Erratum (1992)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 26 (1992), S. 1397-1397 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820261011
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    A comparative study of ultrastructures of the interfaces between four kinds of surface-active ceramic and bone (1992)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 26 (1992), S. 1419-1432 
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    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The interfaces between four kinds of surfaceactive ceramic and bone were studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) using undecalcified specimens. The materials were Bioglass®-type glass (Bioglass®), Ceravital-type glass-ceramic (KGS), apatite and wollastonitecontaining glass-ceramic (A-W · GC) and hydroxyapatite (HA)· Particles of these materials, ranging between about 100 and 300 μm in diameter, were implanted into rat tibiae, and specimens were prepared for observation at 8 weeks after implantation. All materials were observed to bond to bone through a collagen-free layer consisting of fine apatite crytals distinct from those in bone. The crystals of this apatite layer and those of bone were intermingled at their interface, suggesting chemical bonding. In Bioglass®, which had only a glassy phase, several tens of microns of the material surface had changed to such an apatite layer. In KGS and A-W · GC, which had macrocrystals in the glassy phase, an intervening apatite layer about 0.5 μm thick was observed between the materials and bone. Furthermore, fine apatite crystals were also observed among the macrocrystals near the surface of the materials. In HA, which had no glassy phase, an intervening apatite layer was much less distinct and sometimes absent. These differences were considered to be attributable to the differences in chemical composition, crystallization, and solubility of the materials. © 1992 John Wiley & Sons, Inc.
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    Porous polyurethane vascular prostheses with variable compliances (1992)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 26 (1992), S. 1489-1502 
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    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A new technique for the preparation of porous vascular prostheses was investigated. Polyurethane solution (5 to 15 wt%) was injected into a mold. After freezing at low temperature (0°C-196°C), solvents were dissolved out with water at 0°C to form porous tubes. The average pore size (several microns to 70 μm), pore occupation (10% to 51%), and compliance (3% to 35%) were easily changed by changing polyurethane concentration, freezing temperature, and freezing methods. Compliances could be decreased gradually by heat treatment. This technique can give a proper pore size (30-60 μm) for tissue ingrowth, and a suitable compliance for matching with arteries and veins. This method might give a desired compliant graft for artificial implantation with the presently valid medical polymers. © 1992 John Wiley & Sons, Inc.
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    URL: http://dx.doi.org/10.1002/jbm.820261108
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    Toxicity test of biodegradable polymers by implantation in rabbit cornea (1992)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 26 (1992), S. 1463-1476 
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    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: To evaluate whether or not the corneal micropocket implantation is effective for determining the toxicity of polymeric materials, currently used biodegradable polymers such as poly(lactic acid) (PLA), poly(glycolic acid) (PGA), LA-GA copolymers, and three kinds of poly(2-cyanoacrylate)s (PCA) were implanted in a rabbit corneal pouch and the tissue responses were observed macroscopically and microscopically. It was found that PLA induced no vascularization, whereas a residual solvent and ethylene oxide gas remaining in the PLA matrix invoked vascularization. Vascularization clearly took place when PGA was implanted in the cornea, which became opaque, probably because of cellular infiltration. In the case of PCA implantation, severe inflammation as well as vascular invasion occurred in the initial stage. It is likely that these tissue reactions were caused by the leachables from the implanted materials, the extent being dependent on the leaching rate and the toxicity. It was concluded that the corneal micropocket assay is a good means to detect trace amounts of leachables from implanted materials without sacrificing the animals with the implanted materials. © 1992 John Wiley & Sons, Inc.
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    Avoidance of photoactivation in the epifluorescence video microscopic observation of thrombosis (1992)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 26 (1992), S. 1535-1542 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/jbm.820261111
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    In vitro and in vivo digestion of collagen covalently immobilized onto the silicone surface (1992)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 26 (1992), S. 1569-1581 
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    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 in vivo digestion of immobilized collagen and gelatin, these proteins labeled with 125I or fluorescein isothiocyanate (FITC) were covalently immobilized onto silicone surfaces, which were grafted with acrylic acid to introduce carboxyl groups, and implanted subcutaneously in rats and mice. When the proteins were labeled with FITC, the amount of proteins immobilized decreased with the increase of the number of FITC molecules conjugated with the protein molecule. In the wet state, FITC conjugated with the proteins was less stable than 125I. Approximately half of the amount of the immobilized proteins was digested in vivo within the first week and until 5 weeks after implantation the proteins were gradually digested. At that time, the amount of the proteins remaining on the silicone surface ranged from 0.6 to 1.0 μg/cm2, which was several times larger than the amount of an assumed monolayer adsorption of proteins. Even after 15 weeks, the amount of proteins remaining on the silicone was almost the same as after 5 weeks. No significant difference in digestion was observed between collagen and gelatin, regardless of the labeling agent. Because of less stability and easier handling of FITC and higher stability and more difficult handling of 125I, FITC seems more suitable for short-term and 125I for long-term studies. © 1992 John Wiley & Sons, Inc.
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    URL: http://dx.doi.org/10.1002/jbm.820261204
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    Changes in fibrinogen adsorbed to segmented polyurethanes and hydroxyethylmethacrylate-ethylmethacrylate copolymers (1992)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 26 (1992), S. 1633-1649 
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    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Fibrinogen adsorption from blood to biomaterials may regulate platelet adhesion and thrombus formation because of fibrinogen's central role in the coagulation cascade and its ability to bind specifically to the platelet membrane glycoprotein (GP) IIb-IIIa. Adsorption of fibrinogen from blood plasma to many materials exhibits a maximum with respect to plasma dilution and exposure time (the Vroman effect). In this study fibrinogen adsorption to several polymers was examined to ascertain the influence of controlled changes in surface chemistry on the Vroman effect. The materials included hydroxyethylmethacrylate-ethylmethacrylate (HEMA/EMA) copolymers, Biomer, and a series of segmented polyurethanes (PEUs), two of which contained fluorinated chain extenders. Each material exhibited maximal adsorption of fibrinogen at intermediate plasma concentrations. Little effect of soft-segment type or molecular weight was observed and no significant differences in fibrinogen adsorption to the fluorinated PEUs were seen. Changes in the strength of fibrinogen attachment to these materials with time after adsorption were also assessed. Fibrinogen adsorbed for 1 min was displaced more readily by blood plasma than that adsorbed for 1 h, regardless of the material. The more hydrophobic polymers exhibited greater retention of adsorbed fibrinogen. In addition, the fraction of fibrinogen retained by polyethylene depended on the amount of fibrinogen adsorbed to the surface, being greatest when the surface loading was the least. These studies indicate that spreading or transition of adsorbed fibrinogen molecules from a weakly to tightly bound state is a general consequence of protein adsorption to solid surfaces. © 1992 John Wiley & Sons, Inc.
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    Effect of sulfonation of segmented polyurethanes on the transient adsorption of fibrinogen from plasma: Possible correlation with anticoagulant behavior (1992)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 26 (1992), S. 39-57 
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    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The influence of polyurethane sulfonation on fibrinogen adsorption from plasma and on plasma coagulation has been investigated. Sulfonated polyurethanes were synthesized using a two-step solution polymerization in which a diamino disulfonic acid was used as chain extender, thus incorporating sulfonate groups into the hard segments. Polymer molecular weights were determined by size exclusion chromatography and weight average values were in the range of 50,000 to 200,000. Equilibrium water uptake of solid polymer specimens was substantial and was found to increase with increasing sulfonate content. Titration of sulfonate groups allowed an estimate of the retention of free sulfonate in the polymers which ranged from 50 to 85%. Loss of free sulfonate is attributed to reaction of isocyanate with sulfonate groups during chain extension. Both surface chemistry and hydrophilicity were assessed using a combination of ESCA and water contact angle measurements. The ESCA data indicate enrichment of soft segment in the surface. Contact angles show increasing hydrophilicity with increasing sulfur content. Fibrinogen adsorption from plasma to the sulfonated polyurethane surfaces was studied using radioiodine labeling. Fibrinogen surface concentration was found to increase strongly as sulfonate content increased. Fibrinogen adsorption behavior is quite different from that of conventional unsulfonated polyurethanes in the sense that the adsorption levels are much higher and there is little displacement of initially adsorbed fibrinogen (Vroman effect). The data are interpreted i n terms of two mechanisms: fibrinogen uptake (i.e., absorption) into a polymer-plasma “gel” hypothesized to exist at the surface of these materials, and adsorption in the usual sense. Thrombin times of human plasma in which polymer particles were suspended were prolonged and were found to increase with increasing sulfonate content of the polymers, suggesting that sulfonate groups confer a measure of anti-coagulant activity on these materials.
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    Formation of a multilayer cellular lining on a polyurethane vascular graft following endothelial cell sodding (1992)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 26 (1992), S. 103-117 
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    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Small-diameter (〈6 mm) clinically available vascular grafts often fail due in part to the inherent thrombogenicity of artificial polymers. Transplantation of endothelial cells onto the lumen of these vascular grafts has been suggested as one method to overcome this thrombogenicity. We have developed a compliant polyurethaneurea (PEUU) 4-mm graft with a luminal surface modified by a glow discharge gas plasma. Autologous microvessel endothelial cells were isolated from canine falciform ligament fat, were transplanted onto the luminal surface of the grafts using an intraoperative isolation and sodding technique, and both endothelial-cell-treated and non-cell-treated grafts were placed as bilateral carotid interposition grafts in a canine model. After 5 weeks of implantation, explanted control (non-cell-treated) grafts exhibited a deposition of platelets, white cells and fibrin characteristic of a thrombogenic surface. MVEC sodded grafts exhibited a multicellular lining within but distinct from the lumen of the PEUU graft. The blood-contacting surface of this lining exhibited an antithrombogenic endothelial cell monolayer. We suggest that the PEUU graft supported the initial deposition of MVEC and development of an endothelial cell lining. During the 5 weeks of implantation this lining continued to proliferate and detached from the PEUU graft substratum. The final neocellular lining exhibited a luminal diameter and histological features similar to a native artery.
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    URL: http://dx.doi.org/10.1002/jbm.820260110
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    Biological response to chopped-carbon-fiber-reinforced peek (1992)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 26 (1992), S. 133-146 
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    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Polymer composites are being recognized as important implant materials for fracture fixation plates. The use of a composite material is dependent upon the mechanical properties of the material and its biocompatibility. The primary objective of this project was to evaluate 30% chopped-carbon-fiber-reinforced poly(etherether- ketone) (CFRPEEK) as a potential material for use as a fracture fixation plate. A two- phase study was conducted. The first phase analyzed the short-term biocom-patibility of CFRPEEK through rabbit muscle implant testing. CFRPEEK exhibited a nonspecific foreign body tissue reaction similar to the response observed with ultra-high-molecular-weight polyethylene (UHMWPE). In the second phase, four-hole CFRPEEK plates were implanted as internal fixation devices for transverse midshaft femoral osteotomies in beagles. The plates were effective in promoting fracture healing. A nonspecific foreign body reaction was observed to the plates and to particulate debris.
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    Microbial adherence on poly(methyl methacrylate) (PMMA) surfaces (1992)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 26 (1992), S. 197-207 
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    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Infection remains a major complication following the use of implanted biomaterials. Often these infections are caused by low-virulence organisms or by a mixture of organisms (polymicrobial). In this study two methods were used to quantitate the bacteria which had adhered to poly(methyl methacrylate) (PMMA) samples. The bacteria were eluted from the sample using an ultrasonic cleaner. The number eluted was then counted by colony counts, which determines viable organisms and by particle counting which counts both viable and nonviable organisms. A known adherent strain of Staphylococcus epidermidis and a strain of Proteus mirabilis were used. In general the adherence of S. epidermidis was greater than that of Proteus. When the two organisms were used together, there was an alteration in the adherence pattern which generally increased the adherence of Proteus and had no effect or decreased the adherence of S. epidermidis. The use of both quantitation techniques provided important information on the adherence of organisms to PMMA to which gentamicin had been added. It was evident that organisms did adhere to the PMMA plus gentamicin samples but were not viable when eluted. The amount of adherence to PMMA plus gentamicin was similar to that of PMMA alone at 30 min but was markedly decreased at 24 h. There was a considerable dead biofilm mass on the PMMA plus gentamicin samples which might be a significant promoter of late infections by providing a surface attractive to other strains of bacteria.
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    Erratum (1992)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 26 (1992), S. 269-269 
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    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820260211
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    Variations between Biomer™ lots. I. Significant differences in the surface chemistry of two lots of a commercial poly(ether urethane) (1992)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 26 (1992), S. 273-289 
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    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: We have studied the surface chemistry of two lots of Biomer™ (BSP067 and BSUAOOl), and widely used commercial poly(ether urethane) (PEU). Although transmission infrared adsorption studies revealed no differences in the bulk chemistry of the two lots, the surface chemistry, as seen by x-ray photoelectron spectroscopy (XPS) and static secondary ion mass spectrometry (SIMS), was different. Lot BSP067 showed softsegment enrichment at the surface, which is typical of PEU. Lot BSUAOOl showed no evidence of either hard- or soft-segment PEU components at the surface. The surface of this lot was completely covered with a nonextractable additive identified as poly(diisopropy1 amino ethyl methacrylate). Small amounts of a low-molecular-weight antioxidant were observed at the surface of both samples. Because the biological response to polymers is dependent on surface structure, these results are of considerable importance to biomaterials research.
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    Compositional dependence of calcium phosphate layer formation in fluoride bioglasses® (1992)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 26 (1992), S. 1147-1161 
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    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Bioglasses® form a double layer composed of apatite and a silica-rich layer when placed in a simulated physiological solution as well as in living tissue [A. E. Clark, C.G. Pantano, and L. L. Hench, „Auger spectroscopic analysis of bioglass corrosion films,“ J. Am. Ceram. SOC., 59(1-2), 37-39 (1976).]. In the present work, the mechanisms of the calcium phosphate layer and the silica-rich layer formation of fluoride Bioglassesm i n Tris-buffer solution are studied as a function of the SiOz content. Fourier Transform Infrared Reflection Spectroscopy (FTIRS) is used to investigate the mechanism of formation of calcium phosphate and silica-rich layers on the glass surface. Ion concentration in reacted solution and elemental depth profiles are obtained by Induced Coupled Plasma Atomic Emission Spectrometry (ICP) and Auger Elect on Spectroscopy (AES), respectGely. Si—O bonds with one nonbridging oxygen and Si—O—Si bonds form at the early stage of reaction. Strong phosphorus ion uptake occurs when an amorphous calcium phosphate layer crystallizes. Glasses with high silica content (conventional glass) form the silica-rich layer first followed by a calcium phosphate layer on top. However, glasses with low silica content (invert glass) form both layers simultaneously. The rate of apatite formation decreases with increasing SiOz content, especially in the region of conventional glass compositions. Ion release rates decreases as Si02 content increases, with a significant change occurring at the compositional boundary between invert and conventional glasses. © 1992 John Wiley & Sons, Inc.
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    Biomaterials: Taming the beast (1992)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 26 (1992), S. 1-5 
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    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820260102
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    Acoustic emission during fatigue of porous-coated Ti-6Al-4V implant alloy (1992)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 26 (1992), S. 19-38 
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    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Acoustic emission (AE) events and event intensities (e.g., event amplitude, counts, duration, and energy counts) were recorded and analyzed during fatigue loading of uncoated and porous-coated Ti-6A1-4V AE source location, spatial filtering, event, and event intensity distributions were used to detect, monitor, analyze, and predict failures. AE provides the ability to spatially and temporally locate multiple fatigue cracks, in real time. Fatigue of porous-coated Ti-6A1-4V is governed by a sequential, multimode fracture process of: transverse fracture in the porous coating; sphere/sphere and sphere/substrate debonding; substrate fatigue crack initiation; slow and rapid substrate fatigue crack propagation. Because of the porosity of the coating, the different stages of fracture within the coating occur in a discontinuous fashion, There-fore, the AE events generated are intermittent and the onset of each mode of fracture in the porous coating can be detected by increases in AE event rate. Changes in AE event rate also correspond to changes in crack extension rate, and may therefore be used to predict failure. AE offers two distinct advantages over conventional optical and microscopic methods of analyzing fatigue cracks-it is more sensitive and it can determine the time history of damage progression. The magnitude of the AE event intensities increased with increasing stress. Failure mechanisms are best differentiated by analyzing AE event amplitudes. Intergranular fracture and microvoid coalescence generated the highest AE event amplitudes (100 dB), whereas, plastic flow and friction generated the lowest AE event amplitudes (55-65 dB). Fractures in the porous coating were characterized by AE event amplitudes of less than 80 dB.
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    Erratum (1992)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 26 (1992), S. 555-555 
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    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820260411
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    Preparation of dense hydroxylapatite or rhenanite containing bioactive glass composites (1992)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 26 (1992), S. 663-674 
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    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The effect of time at 600°C and of small additions of Al2O3 and B2O3 on the sintering of two composite materials of (1) hydroxylapatite (C ∼I O (P O ∼)∼(O H )∼) and bioactive glass (SiO2-CaO-P2O5-Na2O) or (2) rhenanite (CaNaPO,) and bioactive glass were studied. Scanning microscopy, quantitative EDX, x-ray diffraction, helium gas density measurements, and diametral measurements were performed on the resulting composites. No reactions were observed with the SEM or XRD between the hydroxylapatite particles and the glass matrix within sufficient sintering times to achieve maximum density. (∼) The rhenanitecontaining composites were observed to form Na2O2CaO3SiO2 crystals by x-ray diffraction, probably as a result of dissolution of the rhenanite particle surfaces into the glass phase, the crystals formed in the glass or at the interface of the glass, and the ceramic particles. However, within the short sintering times needed to achieve maximum density the rhenanite particles remained mostly intact. The rhenanitecontaining materials gave better results than the hydroxylapatite-containing materials. The glass composition had a great effect on the densification process.
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    Development of FRP composite structural biomaterials: Ultimate strength of the fiber/matrix interfacial bond in in vivo simulated environments (1992)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 26 (1992), S. 593-606 
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    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Fiber reinforced polymer (FRP) composites are being developed as alternatives to metals for structural orthopedic implant applications. FRP composite fracture behavior and environmental interactions are distinctly different from those which occur in metals. These differences must be accounted for in the design and evaluation of implant performance. Fiber/ matrix interfacial bond strength in a FRP composite is known to strongly influence fracture behavior. The interfacial bond strength of four candidate fiber/matrix combinations (carbon fiber/polycarbonate, carbon fiber/polysulfone, polyaramid fiber/polycarbonate, polyaramid fiber/ polysulfone) were investigated at 37°C in dry and in vivo simulated (saline, exudate) environments. Ultimate bond strength was measured by a single fiber-microdroplet pull-out test. Dry bond strengths were significantly decreased following exposure to either saline or exudate with bond strength loss being approximately equal in both the saline and exudate. Bond strength loss is attributed to the diffusion of water and/or salt ions into the sample and their interaction with interfacial bonding. Because bond degradation is dependent upon diffusion, diffusional equilibrium must be obtained in composite test samples before the full effect of the test environment upon composite mechanical behavior can be determined.
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    Preparation and thrombogenicity of alkylated polyvinyl alcohol coated tubing (1992)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 26 (1992), S. 577-592 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A polyvinyl alcohol hydrogel (PVA) was reacted with a CI8 isocyanate at 80°C in dimethyl formamide (DMF) in order to improve the platelet reactivity of the hydrogel through an inf hence on albumin adsorption or retention. A C, isocyanate was used as a control. Surface coverage by XPS appeared to be ∼100% for both C4 and C18 modified surfaces, although the limited solubility of C18 isocyanate in DMF may have resulted in a nonuniform surface. Relative to PVA or the solvent treated control, octadecylation resulted in increased albumin adsorption (from a single protein solution) and increased retention when the adsorbed albumin was exposed to a fibrinogen solution. However, octadecylation did not obviate the platelet reactivity problem in preliminary studies: systemic platelet counts were reduced by about half over 4 days in a canine AV shunt experiment and the initial rate of platelet destruction for C IR-PVA was greater (36%/ day) even than for the solvent-treated PVA. Surprisingly in preliminary studies butylation of PVA resulted in little or no thrombocytopenia and did not appear to increase significantly the fractional rate of platelet destruction relative to the shunt only blank. It is presumed that the nonspecific effect of alkylation (independent of chain length) was the dominant contribution to the reduced platelet reactivity. A similar effect of C18-PVA presumably would have been observed had the limited solubility of C18 isocyanate not precluded a uniform surface coverage.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/jbm.820260503
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    Difference in tumor incidence and other tissue responses to polyetherurethanes and polydimethylsiloxane in long-term subcutaneous implantation into rats (1992)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 26 (1992), S. 631-650 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The long-term (1- and 2-year) adverse tissue responses including tumor formation by subcutaneous implanation of polyurethanes (PUS) and silicone (Sil) films intorats were compared. The weight-averaged molecular weights (Mw) of the PUS prepared from 4,4′-diphenylmethanediisocyanate, poly (tetramethyleneglycol) of M, = 1000 and 1,4-butanediol are 220,000 (U-4), 124,000 (U-6), and 55,600 (U-8). The 50:50 mixed film of U-6 and silicone (U-b/sil) was prepared by rollmixing of the noncured silicone and the U-6 solution followed by evaporation of the solvent and heat-curing at 70°C. The tissue responses around implants were classified into four groups as follows: (A) tumor, (B) atypical cell proliferation accompanied by preneoplastic changes, (C) cell proliferation without preneoplastic changes, (D) no obvious responses. In both implantation periods, the PUS gave higher incidents of the adverse responses including tumor formation in comparison to Sil. No significant molecular weightdependent trend was found in a 1-year study using U-4, 6, and 8. Significant PU-dose-dependent trends were found in a 2-year study: the total active incidence (A + B + C), U-6(22/29) 〉 U-6/si1(11/29) 〉 sil(7/28); tumor incidence (A), U-6(11/29) 〉 U-6/si1(2/29) = si1(2/28). No detectable amounts of 4,4′-methylenedianiline (MDA) were found in the PUS. The methanol extracts from the PUS were negative in the mutagenicity tests. These indicate no relationship between the tumor formation by the PU films and the mutagenicities of the chemicals (mainly oligomers) leached from the PUs.
    Additional Material: 4 Ill.
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    URL: http://dx.doi.org/10.1002/jbm.820260506
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    Measurement of the rate of thrombin production in human palsma in contact with different materials (1992)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 26 (1992), S. 675-693 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Thrombin production in plasma in contact with various materials was consistent with a first-order autocatalytic model (d[T]/dt = k,[T]; [TI] = thrombin concentration, t = time, k, = thrombin production rate constant) since the initial portion of a semilogarithmic plot of thrombin concentration against time was linear. Thrombin concentration was measured in clotting plasma (phospholipid enhanced or plateletrich plasma) using fluorogenic substrate (BMCA) by aliquot sampling at various intervals or more conveniently by monitoring cumulative fluorescence. The latter was generated by the action, on BMCA incubated in the clotting plasma, of the thrombin as it was generated. The thrombin concentration was determined from the first derivative of the S-shaped cumulative fluorescence curve. kp, was greater for glass (7.92 × 10-3 cm/than) for the other materials (polypropylene, polystyrene, polyethylene and PVA; kp, ∼3.1 × 10-3cm/s) in plasma with cephalin without flow. A kp, for heparin PVA could not be determined since the thrombin concentration was too low to be quantified. A larger difference between polyethylene and PVA was noted with platelet-rich plasma without flow while lower values (1.0 × cm/s) were noted in a flow system but at a higher surface to volume ratio. The first-order rate constant can be used in simple models relating production of thrombin at a wall of a tube to its mass transfer away from the wall in flowing blood. One such model predicts that the concentration of thrombin at the wall should become infinite at the point in the tube when the mass transfer coefficient equals kp. According to this model, kp on the order of cm/s would be a useful target for a nonthrombogenic material.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/jbm.820260509
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    High-voltage electron microscopy and conventional transmission electron microscopy of the interface zone between bone and endosteal dental implants (1992)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 26 (1992), S. 529-545 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The interface between mandibular bone and endosteal dental implants was examined with an in vivo dog model. Undecalcified mandibular implant samples were observed with both conventional transmission electron microscopy and highvoltage transmission electron microscopy (HVEM). Results demonstrated the variable nature of the interfacial support tissues. Mineralized bone was often found within 50 nm of the implant surface, separated from that surface only by an electron dense deposit. Osteocytes were observed close to the interface encased within lacunae extending numerous cellular processes through canaliculi. An osteoblast was also observed directly at the interface within a developing lacuna. Other interfacial areas exhibited a finely fibrillar and more electron lucent morphology. Furthermore, other areas were shown to be composed of wider zones of extracellular products containing collagen fibrils, ground substance, and calcified inclusions. Because bone is a n actively growing and remodeling tissue, these different morphological zones around the entire area of the implants would appear to confirm the dynamic tissue response to endosteal dental implants. Further, HVEM stereology was shown to be an exciting research tool to investigate this tissue response.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820260409
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  • 94
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    Bone apposition to plasma-sprayed cobalt-chromium alloy (1992)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 26 (1992), S. 557-575 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The use of porous metallic coatings for fixation of total joint prostheses by bone ingrowth has become a widespread alternative to fixation with PMMA bone cement. However, concerns about such coatings include long-term effects of metal ion release, potential coating loss, and decreased substrate fatigue strength. The biological fixation capability of a nonporous, high-integrity plasmasprayed CoCr coating with low surface area was compared to a conventional sintered bead coating in goat cortical and cancellous bone sites after 8 and 16 weeks of implantation. Histological evaluation showed substantial variations in fixation quality between individual animals and between surgical sites with no consistent difference between implant types. Shear testing of bonelimplant interfaces showed that although conventional porous coating exhibited higher overall average shear strengths in cortical bone sites at both time periods, the differences were not statistically significant. In cancellous sites, the average shear strengths achieved with conventional porous and plasmasprayed coatings were essentially equal. Analysis using average paired differences, however, revealed that when porous and plasma-coated implants are placed in identical sites of contralateral limbs, the plasma coatings consistently yielded higher shear strengths in cancellous bone sites at the later time period. Since current design theory for biological fixation favors metaphysical fixation, this surface may offer potential advantages over conventional porous coatings.
    Additional Material: 12 Ill.
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    URL: http://dx.doi.org/10.1002/jbm.820260502
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    A fractographic investigation of PMMA bone cenent focusing on the relationship between porosity reduction and increased fatigue lifeSupported by the William H. Harris Foundation, Boston, MA 02114 (1992)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 26 (1992), S. 651-662 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Fracture surfaces of both monotonic and fatigue loaded bone cement samples were examined to investigate the fractographic characteristics of PMMA. Classic cleavage step river patterns were observed on all monotonically loaded samples, running downstream in the direction of crack propagation. AH fatigue cracks initiated at internal pores and the direction of crack propagation of many cracks was discernible. Porosity, pore size, and pore size distribution were found to affect the crack initiation and fatigue behavior of bone cement. Statistical analysis revealed a strong negative correlation between twodimensional porosity present on the fracture surfaces and the cycles to failure. The fractographic observations of these fatigue samples elucidate one reason why porosity reduction by centrifugation or vacuum mixing increases the fatigue life of PMMA bone cement.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820260507
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    Masthead (1992)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 26 (1992) 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820260601
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    Blood compatibility of SUUU-PEO-heparin graft copolymers (1992)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 26 (1992), S. 739-756 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: Biological responses to heparinized segmented polyurethaneurea (SPUU-PEO-Heparin) were evaluated in uitro and ex vivo. In uitro assays involved plasma protein adsorption, platelet adhesion, and release reaction studies. In addition, an ex vivo rabbit arterio-artery (A-A) shunt experiment was also performed to measure occlusion times of the heparinized surfaces. All SPUU-PEO-Heparin surfaces demonstrated less protein adsorption than Biomer® and protein adsorption patterns similar to SPUU-PEO surfaces. Platelet adhesion and release studies demonstrated that both SPUU-PEO-Heparin and SPUU-PEO surfaces adsorbed less platelets and inhibited platelet release, as compared to Biomerm. These findings correlated with reduction in protein adsorption observed for the modified surfaces. In low flow rate ex-vivo A-A shunt experiments, all heparinized surfaces prolonged occlusion time longer than controls. However, SPUU-PEO surfaces did not prolong occlusion time whencompared to BiomerB, although these surfaces suppressed protein adsorption and platelet interaction in vitru. The improved blood compatibility of SPUU-PEO-Heparin surfaces attest to the usefulness of this approach in improving the blood compatibility of blood contacting surfaces.
    Additional Material: 12 Ill.
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    URL: http://dx.doi.org/10.1002/jbm.820260605
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    Effect of soft segment chemistry on the biostability of segmented polyurethanes. II. In vitro hydrolytic degradation and lipod sorption (1992)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 26 (1992), S. 801-818 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A series of segmented polyurethanes (SPUs) with various polyol soft segments was prepared and their hydrolytic degradation and degradation due to lipid sorption was investigated. The hydrolytic degradation of the SPUs was investigated in a papain solution, where it was shown that the SPU based on poly(ethy1eneoxide) (PEO) soft segment was susceptible to hydrolytic degradation. X-ray photoelectron spectroscopic (XPS) data suggest dissociation of the urethane linkage by enzymatic degradation. Degradation by lipid sorption was observed for the SPU based on a poly(dimethylsi1oxane) (PDMS) soft segment. This is ascribed to the high solubility of lipid in the PDMS segment of the SPU.
    Additional Material: 14 Ill.
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    URL: http://dx.doi.org/10.1002/jbm.820260609
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    Stimulation of neutrophil movement by metal ions (1992)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 26 (1992), S. 819-828 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The interaction between corrosion products of metallic implants and the surrounding tissue is important in determining the biocompatibility of the implant, in particular the interaction of corrosion products with inflammatory cclls such as neutrophils and macrophages. Such cells are capable of releasing enzymes and high-energy oxygen radicals which can damage the tissue. Clearly, any factors that influence cell movement to the implant site could influence the biocompatibility of the implant. The present study examined the influence that copper and nickel ions had on neutrophil locomotion. Both copper and nickel ions stimulated a proportion of the neutrophil population to take up a nonspherical morphology and to locomote. These metal ion stimulated cells have higher circularity values and move slower than neutrophils incubated with FM1.P. For both FMLP and nickel ion stimulated cells, there is a correlation between the speed of neutrophil locomotion and neutrophil circularity; as the neutrophil circularity value decreases, the speed of locomotion increases.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820260610
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  • 100
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    TNF and IL-1 generation by human monocytes in response to biomaterials (1992)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 26 (1992), S. 851-859 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: The biocompatibility of surgically implanted materials may be compromised as a consequence of inflammatory reactions associated with phagocyte activation. Two important mediators of the inflammatory response are Interleukin-1 (IL-1) and tumor necrosis factor (TNF), both of which exert a wide range of biologic effects on many cells. This study was designed to evaluate the release of these cytokines by human monocytes (HM) brought into contact with four biomaterials utilized in clinical practice: polyurethane, expanded polytetrafluorethylene (ePTFE), Dacron velour, and woven Dacron. In vifro cultures for the generation of IL-1 and TNF by HM in the presence of the above biomaterials were established by exposing cells to each bio material in the presence and absence of lipopolysaccharide (LPS) with harvest of supernatants after 6 or 18 h. These studies showed that in the absence of LPS, IL-1 was released only by Dacron velour and woven Dacron associated monocytes while TNF was secreted in response to all of the materials. When LPS was present, however, monocytes associated with all of the materials released IL-1; and TNF release was greatly augmented. Further, the quantity of released cytokine was directly related to the duration of the association time. This study demonstrated that HM in association with various biomaterials were ctivated to produce both TNF and IL-1 and that the addition of nanogram quantities of LPS, such as would be produced if infection were present, greatly increased the amount of cytokines released.
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    URL: http://dx.doi.org/10.1002/jbm.820260703
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