ISSN:0021-9304    

DOI:10.1002/jbm.820231102

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThein vivobiocompatibility of metals coated with several different types of ceramics [alumina (α‐Al2O3), titanium oxide (TiO2), titanium nitride (TiN), and hydroxyapatite (HAP)] was investigated. These composites had been devised for the purpose of incorporation into the stem of a total hip prosthesis. The materials were inserted into the mid‐diaphyseal region of the femurs of adult dogs, and follow‐up quantitative histological comparisons were performed for a period of up to 96 weeks. HAP‐coated composites showed the best biocompa

ISSN:0021-9304    

DOI:10.1002/jbm.820231103

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractHuman serum was incubated with representative portions of polyvinyl chloride (PVC) blood storage bags and vascular prostheses. Thein vitrointeraction process with lipo‐protein was followed by polyacrylamide gel electrophoresis (PAGE) using sudan black and nitroblue tetrazolium (NBT) in the prestaining procedure. Densitometric scan of all the lipoprotein bands in serum after incubation with PVC bag material when prestained with sudan black showed remarkable increase in intensity. However, in the same experiment when NBT was used for prestaining no increase in the intensity of any of the lipoprotein bands could be observed. Since sudan black is known to bind cholesterol specifically we suggest that a molecular unfolding occurs when lipoprotein interacts with PVC bag material. When similar experiments were carried out with vascular prosthesis there was conspicuous decrease in the intensity of the high‐density lipoprotein (HDL) band especially when stained with NBT. This indicates preferential adhesion of HDL during interaction with vascular prosthe

ISSN:0021-9304    

DOI:10.1002/jbm.820231104

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractA series of copolymers of glycine and DL‐lactic acid with various compositions was synthesized and theirin vivoandin vitrodegradation behavior was studied. For thein vivoexamination, discs of the copolymer films were subcutaneously implanted in rats. Thein vitrostudies were carried out in phosphate buffer at pH = 7.4 and 37°C. The decrease in molecular weight, the loss of weight, and the tissue reactions of the different copolymers were determined after 2, 5, and 10 weeks. Poly(DL‐lactic acid) was used as reference material. Thein vivoandin vitrodegradation behavior of the polymers was comparable. The decrease of molecular weight of the copolymers and poly(DL‐lactic acid) in time was similar. The weight loss for copolymers with a higher mole fraction of glycine units started earlier. The copolymer with the highest content of glycine units disappeared completely within 10 weeks bothin vivoandin vitro. The poly(DL‐lactic acid) implant lost only 25% weight over the same period. Tissue reactions against all materials started with an acute inflammatory reaction caused by the trauma of implantation, followed by wound‐healing processes, ending in a very mild foreign body reaction for the poly(DL‐lactic acid) and a more excessive macrophage mediated foreign body reaction for the glycine/DL‐lactic acid copolymers. The tissue reaction was more severe for polymers having a higher rate

ISSN:0021-9304    

DOI:10.1002/jbm.820231105

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractBioactive glass fibers have been prepared and implanted in cortical defect and in muscle. The fibers can act as a substrate for bone apposition, when implanted in a cortical defect, and become incorporated in the new bone matrix. The same results were obtained when fibers were implanted in a muscle pouch together with bone marrow cells. An intense inflammatory reaction was observed when bioactive glass fibers were implanted in muscle; the reaction was milder when fibers were implanted in bone or in muscle together with bone marrow cells. This fact supports the hypothesis that osteogenic cells adhere in an early phase to the substrate and prevent recognition of the foreign material by inflammatory cells. This appears to be a fundamental condition for direct bone matrix apposition on the surface of fibers.

ISSN:0021-9304    

DOI:10.1002/jbm.820231106

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThis article deals with thein vivoevaluation of a new class of synthetic polypeptides, the poly[(tert‐butyloxycarbonylmethyl) glutamates], POMEG, as an injectable or implantable drug delivery system. Three different polymers, varying in their degree of esterification, were extruded either with or without progesterone, and finally implanted in rats up to 14 days. Histologic evaluation of the implant sites show evidence of the good biocompatibility of these polymers. In addition, the description of theirin vivobehavior, based on microscopic observation of the implanted POMEG rods, enables one to appreciate their potential as a drug delivery system for short‐ or long‐term th

ISSN:0021-9304    

DOI:10.1002/jbm.820231107

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractThe present article builds on elementary fluid dynamics and previous analyses by the author to delineate approximate boundaries of mural thrombus heightHP, maximum shear rate\documentclass{article}\pagestyle{empty}\begin{document}$ \dot \gamma _{{\rm Max}} $\end{document}, and flow pulsatility beyond which thrombi are subject to either very high or very low probabilities of embolization. A thrombus height of ∼0.1 mm emerges as a critical dividing line: Below it, the maximum embolizing shear stress τsis independent of thrombus height and varies only linearly with shear rate. Above it, τsquickly approaches a strong quadratic dependence on both thrombus height and shear rate:\documentclass{article}\pagestyle{empty}\begin{document}$ \tau _{\rm s} \sim (H_{\rm p} \dot \gamma)^2 $\end{document}, significantly increasing the likelihood of an embolizing event. By contrast, convective‐diffusive removal of blood components during the initial stages of thrombus formation varies only weakly with\documentclass{article}\pagestyle{empty}\begin{document}$ \dot \gamma ^{{1 \mathord{\left/ {\vphantom {1 3}} \right. \kern-\nulldelimiterspace} 3}} $\end{document}in all but the smallest vessels. These maximum embolizing stresses are due principally to fluid drag. Acceleration (pulsatile) forces only begin to make their presence felt at\documentclass{article}\pagestyle{empty}\begin{document}$ {\dot \gamma} $\end{document}<500 s−1and reach parity with fluid drag at\documentclass{article}\pagestyle{empty}\begin{document}$ {\dot \gamma} $\end{document}∼ 10 s−1, i.e., at a level where the presence of pulsatility is questionable. The results are used to provide maps of domains with high and low probabilities of an embolytic event and of vessel patency. The maps reveal that relatively modest changes in shear rate and/or vessel lumen can cause shifts from high to low likelihood of vessel patency, opening up possible ways of controlling blockage by manipulation of thes

ISSN:0021-9304    

DOI:10.1002/jbm.820231108

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractBiocompatibility and diffusional characteristics of recently synthesized unique amphiphilic newtworks, i.e., copolymers of methaycryloyl‐capped polysiobutylene (MA‐PIB‐MA) with 2‐(dimethylamino)‐ethyl methacrylate (DMAEMA) have been examined. Excellent biocompatibility and biostability were obtained after 7 weeks with films containing 53–58% MA‐PIB‐MA implanted dorsally or abdominally in rats. In contras, neworks with higher or lower MA‐PIB‐MA contents showed decreased biocompatibility. These amphiphilic networks were also studied as potential implantable drug release systems. Bromophenol blue and folic acid were used as model compounds for drug release. Diffusion of these chemicals from loaded networks into water showed a marked pH dependence. Under specific well‐defined conditions (MA‐PIB‐MA/DMAEMA content, pH, time range) release was observed to be independent of

ISSN:0021-9304    

DOI:10.1002/jbm.820231109

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractAssessments were made of the safety of antibodies which might be detached from a therapeutic immunoadsorbent (IA) during extracorporeal circulation, with respect to possible immunological responses to such antibodies. The IA used was antihuman IgE antibody (a‐IgE Ab) immobilized on a carrier, for removal of IgE from patients' plasma. The antibody was raised in goats and isolated to give an IgG fraction. This fraction was either used without further purification or was subjected to immunoaffinity purification. The active anaphylaxis test in guinea pigs indicated that positive responses were not observed at doses of less than 0.1 μg of goat IgG per animal. Rabbits given goat IgG intravenously 3 times a week for 8 weeks did not produce the specific antibody against goat IgG at doses of less than 0.05 μg/kg, which corresponds to less than 3 μg for an adult with a body weight of 60 kg. However, none of the rabbits given goat IgG at 2.5 mg/kg showed any toxic reactions and different patterns of the body weight growth from these in the control group. In addition, we tested whether immunoaffinity purified a‐IgE Ab could trigger Type I hypersensitivity in a monkey model. Anaphylactic reactions were not observed after a single intravenous injection of a‐IgE Ab at less than 10 μg/kg. Thesein vivoresults are useful to judge whether the amount of antibody that leaks from a therapeutic IA is acceptable or not in a clinical s

ISSN:0021-9304    

DOI:10.1002/jbm.820231110

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY

摘要:

AbstractGlutaraldehyde (GA) and formaldehyde (FA) were shown to be released from 1 cm2fixed pericard patches into 2‐mL storage solutions after three 2‐min washings in concentrations of about 1 mg/L. The cytotoxicity of these aldehyde concentrations on bovine aortic endothelial cells (BAECs) was evaluatedin vitro, by proliferation capacity, cellular ATP content, PGI2release and cyclic AMP synthesis. Continuous incubation of BAECs with GA>0.1 mg/L and FA>0.5 mg/L resulted in a significantly inhibited proliferation and in an increase of the intracellular Ca2+triggered parameters, PGI2and cyclic AMP, up to three fold. This strongly suggests an aldehyde‐induced inhibition of the plasmamembrane bound Ca2+‐ATPase, an enzyme which normally maintains low intracellular Ca2+‐level. From these findings there is evidence that aldehydes released from bioprosthetic valve tissue may contribute to the lack of endothelial cell coverage in human

ISSN:0021-9304    

DOI:10.1002/jbm.820231111

出版商:John Wiley&Sons, Inc.    

年代:1989

数据来源: WILEY