摘要:

AbstractSponges of the same size made of collagen (CS), polyurethane (PU), polyvinylalcohol (PVA) and acetylcellulose (AC) were inserted for 10 days in the vaginas of 22 rabbits. Light and scanning electron microscopy of the vaginal wall and its mucosal lining showed signs of cytotoxicity only with PU and AC while CS and PVA picture did not differ from sham controls. In order to explain the reasons for the toxic effects, all sponges were extracted into aqueous or organic solvent media and analyzed by gas liquid chromatography. Only several minute peaks in organic solvents were found. Extracts of all sponges tested for cytotoxicity in fibroblast cultures showed significant inhibition of H3–thymidine uptake. Nevertheless, extract of collagen sponge was significantly less cytotoxic than the extracts of all other sponge

ISSN:0021-9304    

DOI:10.1002/jbm.820130103

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractIn six calves an extracorporeal arteriovenous shunt in combination with a successful type of percutaneous lead has been implanted. Flow chambers with various test materials can be inserted. Preliminary results show that this shunt can be used for long term tests for evaluation of blood contact material and studies about thrombus formation in anex vivosetting as well as for permanent blood access for the purpose of various measurements, drug application and for hemodialysis.

ISSN:0021-9304    

DOI:10.1002/jbm.820130104

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractThis investigation studies the relationship of hardness, elastic modulus and scratch width as dependent variables to the abrasion resistance of twenty‐three dental acrylic resins. The multiple correlationR, when all three variables are used as predictors, is 0.727. Because of the significant intercorrelations between the variables themselves a stepwise multiple regression analysis showed hardness as a redundant variable. Abrasive wear can be estimated from the following equation\documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{*{20}c}{{\rm Abrasive\,wear} = 806.1 - 0.1498\,{\rm modulus} + 0.681\,{\rm scratch\,width}} \\{{\rm (}R = 0.725;\,{\rm standard\,deviation\,of\,estimate} \pm {\rm 50}{\rm .8)}} \\\end{array} $$\end{document}The deletion of scratch width does not appreciably reduce the standard deviation of the estimate:\documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{*{20}c}{{\rm Abrasive\,wear} = 1063.4 - 0.2055\,{\rm modulus}}\\{{\rm (}r = 0.683;{\rm standard\,deviation\,of\,estimate} \pm 50.3)}\\\end{array} $$\end{document}The method of curing the specimens conformed to the respective manufacturers' instructions. Abrasion and scratch tests were performed using methods developed by the authors and previously described in the literature, whereas the hardness and elastic modulus results were devised from standard test procedures.Further research is currently in progress to improve the predictive power of abrasion resistance with additional new variable

ISSN:0021-9304    

DOI:10.1002/jbm.820130105

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractIn vitrocorrosion experiments were conducted employing potentiostatic polarization techniques, a saline environment and candidate biomaterial alloy/carbon combinations. Corrosion currents and potentials of carbon/metal couples were predicted by mixed‐potential theory utilizing the polarization curves generated. The alloys examined were annealed ELI grade Ti‐6Al‐4V and cold‐worked 316L stainless steel while the types of carbon examined were LTI pyrolytic carbon and vapor‐deposited carbon. It was determined that galvanic couples of carbon to cold‐worked 316L stainless steel with carbon/metal area ratios of 10:1 to 100:1 produced coupled corrosion potentials in the range of the observed breakdown potential of the stainless steel. It was therefore predicted that localized corrosion in the form of pitting could occur on the cold‐worked stainless steel when coupled to rbon with area ratios of 10:1 or greater. The titanium alloy did not exhibit a breakdown potential up to a potential of 1.2 V. Therefore, accelerated corrosion was not predicted for the titanium alloy to carbon galvanic couples under these experimental conditions. Direct carbon/alloy coupling experiments were conducted to verify the corrosion currents and potentials predicted from mixed‐potential theory and polarization curve analysis. The experimental and theoretical values showed

ISSN:0021-9304    

DOI:10.1002/jbm.820130106

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractThe effect of the exposure to air or to the substrate during the solvent casting process on the surface chemical composition of Avcothane, a blood compatible biomaterial, was studied by employing Auger electron spectroscopy. The surface layer of 10–15Å thickness was analyzed without sputtering, but for the studies probing a deeper layer, argon ion sputtering at a low enough voltage to prevent artifacts was utilized.It is found that the air facing surface which is the blood contact surface contains a greater amount of silicone polymer and a much lower amount of the urethane hard segment in the first 10–15Å‐deep layer than in the comparably thick layer of the substrate surface. However, the depth‐composition profile obtained by sputtering indicate that, probably at a deeper depth, the chemical compositions in terms of silicone polymer and hard segment is comparable both in the air side and the subst

ISSN:0021-9304    

DOI:10.1002/jbm.820130107

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractThe biocompatibility of high‐purity dense Al2O3‐ceramics had been shown to open the possibility of direct cement‐free anchorage of joint endoprostheses. Three years of clinical experience with ceramic‐metal composite total hip prostheses confirm the biomechanical design criteria used for the acetabular components. They also allow for additional conclusions regarding the reaction of bone tissue towards a bioinert implant. Further research activities are directed towards a solution for the biomechanically stable anchorage of the femoral component of hip pro

ISSN:0021-9304    

DOI:10.1002/jbm.820130108

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractThe biocompatibility of alumina ceramic was tested by means of macrophage cultures, intraperitoneal (i.p.) and intramuscular (i.m.) application of powdered particles in rats, and by implantation of solid samples in the paravertebral muscles and the condylus of femur. No acute cytotoxicity was found in macrophage cultures. The i.p. and i.m. application of powdered particles in the beginning showed a granulocytic reaction, later followed by a histiocytic reaction. Also, the morphological changes in the organs of reticulo histiocytic system (RHS) are shown. In the solid sample implantation, the fibrogenetic stimulus is measured by morphological analysis of the connective tissue membrane around the sample. The importance of the individual cell observation by transmission‐electron microscope (TEM) examination is evidenced. The experimental results are compared to the environmental reaction of smaller animal‐adapted prostheses and prostheses having been implanted in human patients. Good biocompatibility is confirmed by these investigations; also regarding central position of the macrophages, the environmental reaction due to implant material is sh

ISSN:0021-9304    

DOI:10.1002/jbm.820130109

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractCompound bone cement on a PMMA base with an additive of bioactive glass ceramic particles in different portions and different particle sizes are tested in animal experiments. The tissue reactions to extracorporal polymerized specimens and to in situ polymerized specimens are observed. The experiments with an implantation period up to six months demonstrate a tight bonding between the newly formed osseous tissue and the glass ceramic particles at the interface. The inflammatory reactions in the vicinity of the implant are small. It is the objective of the investigations to improve the adherance of the bone cement at the interface to achieve a more durable anchorage of bone cement in the tissue.

ISSN:0021-9304    

DOI:10.1002/jbm.820130110

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractThe infection rate of implant sites bearing porous and dense implants was studied in mice. In the first model (acute infection) the mice were injected with Staphylococcus aureus subcutaneously at the implant site at the time of implantation. In the second (chronic) model the implants were left in place for four weeks for encapsulation or invasion to occur and then the organisms were inoculated. In the acute model the infection rate with the porous materials was greater. In the chronic model after tissue invasion the infection rate with the dense materials was greater. This supports the hypothesis that microorganisms can evade host defense mechanisms if they enter the pores of the implant before tissue invasion, but that once the implant is invaded with host tissue the bacteria are less apt to establish infection.

ISSN:0021-9304    

DOI:10.1002/jbm.820130111

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY

摘要:

AbstractIn the present paper a tissue culture technique is described whereby the toxicity of setting and solid materials may be evaluated. A cell monolayer was established on a millipore filter which was placed on an agar medium, cell side down. Test specimens were placed on top of the millipore filter and were allowed to influence the cells through the filter for two hours. The cell reaction was assessed by incubating the cells, still adherent to the filter, for the demonstration of succinate dehydrogenase activity. Materials with a cytotoxic effect caused a zone of inhibited enzyme activity in the cell‐material contact area. The filters were examined macroscopically and scores from 0 to 3 were given to grade the severity of the cell response. Unset and set silicate cement, zinc phosphate cement and an acrylic resin were tested. The results obtained were consistent and in accordance with those of previous reports. The method was simple and rapid and appeared suitable for the assay of larger test serie

ISSN:0021-9304    

DOI:10.1002/jbm.820130112

出版商:John Wiley&Sons, Inc.    

年代:1979

数据来源: WILEY