摘要:

AbstractA microporous filler giving greatly improved finishability, systemic nontoxic X‐ray opacification, low thermal expansion (27.2 × 10−6/°C), and satisfactory translucencies has been developed for dental composite resin restorations. These fillers are prepared from frits obtained by the low‐temperature calcination of gelled inorganic sols followed by a pulsed high‐temperature treatment. Composites prepared from these fillers are within the range of commercial products with regard to strength and setting co

ISSN:0021-9304    

DOI:10.1002/jbm.820120402

出版商:John Wiley&Sons, Inc.    

年代:1978

数据来源: WILEY

摘要:

AbstractEarly work on hip prosthesis showed that the metal component would loosen in bone even when screws were used. This practice resulted in the death and resorption of the bone; thus cement was used in orthopedic surgery for firm implantation of prostheses. In recent years antibiotics have been added to the cement as a prophylaxis against infection.This research investigates the effects of antibiotics on the diametral tensile and compression strength of the cement. Samples made with 2 g of antibiotic per surgical packet of bone cement containing the antibiotics gentamicin, keflin, and a combination of the two were tested. These samples were aged at ambient temperature for periods of 1 day and 1, 2, 8, 13, and over 30 weeks.A statistical analysis using a two‐way analysis of variance with interaction was conducted. It was concluded that the compression strength was affected by the antibiotic, and not by the aging period, but that there is an antibiotic‐aging period interaction. The tensile strength is not affected by either the antibiotic or the aging period, and there is an antibiotic‐aging period interaction. Current work being conducted will analyze additional factors and interac

ISSN:0021-9304    

DOI:10.1002/jbm.820120403

出版商:John Wiley&Sons, Inc.    

年代:1978

数据来源: WILEY

摘要:

AbstractReconstituted bovine collagen has been used extensively in our laboratory as a carrier for immobilizedE. coliL‐asparaginase. The activity and catalytic stability of these collagen–asparaginase membranes can be altered substantially by conditions used in membrane crosslinking with glutaraldehyde. As the concentration of glutaraldehyde used in tanning is increased, the initial specific activity of collagen–asparaginase membranes decreased asymptotically to a limiting value. Similar results occurred when membranes were subjected to increasing time periods of tanning at a constant glutaraldehyde concentration. These observations point to a time‐concentration relationship for glutaraldehyde tanning and its effect on the specific activity of collagen–asparaginase membranes. Specific activities of membranes tanned at glutaraldehyde concentrations of 5% or higher appear to be very stable over long periods of alternate storage and assay. This result, however, is not observed with membranes tanned at glutaraldehyde concentrations lower than 5% for short periods of time (approximately 30 sec to 1 min). It is not clear whether the instability of membranes tanned at lower concentrations of glutaraldehyde or shorter intervals of tanning is due to enzyme elution from the membrane or denaturation of the bou

ISSN:0021-9304    

DOI:10.1002/jbm.820120404

出版商:John Wiley&Sons, Inc.    

年代:1978

数据来源: WILEY

摘要:

AbstractInitial rates of ion‐exchange adsorption of nickelous or cupric ions with calcium ions on the surface of synthetic hydroxyapatite were studied in aqueous nitrate solutions. A kinetic interpretation has been proposed. The determination of the initial rates is important for a systematic investigation of adhesion of certain properly designe substances that may mediate a chemical bonding between dental resins and “moralanted” calcified ti

ISSN:0021-9304    

DOI:10.1002/jbm.820120405

出版商:John Wiley&Sons, Inc.    

年代:1978

数据来源: WILEY

摘要:

AbstractThe growth of tissue‐cultured aortic endothelial cells from the calf using 12 different configurations of Dacron polyester (U.S. Catheter and Instrument Co.) as substrates was studied. Scanning electron microscopy showed maximum cell coverage on tightly knit configurations, whereas loose knits and velours did not support cell growt

ISSN:0021-9304    

DOI:10.1002/jbm.820120406

出版商:John Wiley&Sons, Inc.    

年代:1978

数据来源: WILEY

摘要:

AbstractAntiinflammatory activities of low‐ and high‐ molecular‐weight polymers ofo‐methacryloyloxybenzoic acid were compared with the antiinflammatory activity ofo‐acetoxybenzoic (acetylsalicylic) acid in tests on hind‐leg inflammations in rats induced by injection of either Freund's adjuvant or aqueous suspension of kaolin. The antiinflammatory activies of the orally administered polymers cooresponded to 40–90% of the activity ofo‐acetoxybenzoic acid, and were not substantially dependent on the degree of

ISSN:0021-9304    

DOI:10.1002/jbm.820120407

出版商:John Wiley&Sons, Inc.    

年代:1978

数据来源: WILEY

摘要:

AbstractThe solution of charged sodium dextran sulfate (molecular weight 6000) co‐reacted with that of oppositely charged chitosan to form a water‐insoluble hydrous complex, whose clot‐inhibiting property was sensitive to such reaction conditions as the order of mixing, the kind of acid species used for the adjustment of pH, and the concentration of hydrogen ion at which the preparation of polyelectrolyte complex was carried out, although all the polyelectrolyte complexes were prepared from the same starting materials. In order to clarify the relationship between the molecular conformation of the polyelectrolyte complex and its clot‐inhibiting property, ir spectroscopic studies,in vitroblood‐clotting tests, color reaction with toluidine blue, elemental analyses, and so on, were performed. Consequently, it was suggested that the polyelectrolyte complexes consisting of sodium dextran sulfate of lower molecular weight are more clot‐inhibiting than those with higher molecular weight. It was also found that polyelectrolyte complexes prepared under the mixing order of sodium dextran sulfate solution added to chitosan solution are also more clot‐inhibiting than those prepared under the reverse mixing order, chitosan solution added to sodium dextran sulfate solution. Furthermore, it has become apparent that the anticlotting polyelectrolyte complexes have some characteristic ir absorption bands, and that they displayed color reaction with toluidine blue. A new possibility may be anticipated from our experimental results, providing important information relating to realizing a functional polymer, antithrombogenic material, whose property m

ISSN:0021-9304    

DOI:10.1002/jbm.820120408

出版商:John Wiley&Sons, Inc.    

年代:1978

数据来源: WILEY

摘要:

AbstractThe corrosion of carved, burnished, polished, and burnished–polished samples of a conventional spherical amalgam was studied by anodic polarization in Ringer's solution. The effect of the variation of the mercury content from 40 to 60 wt% on the corrosion of burnished or polished samples was also investigated. It was found that burnished and burnished–polished samples corrode the least and carved samples the most. The current‐density peak associated with γ2was of greater magnitude in polished specimens than in burnished specimens throughout the range of mercury concentrations investigated. It is hypothesized that lower porosity and more ready passivation of the surface due to a high amount of γ2are the reasons that burnished samples corroded less than polished samples in this anodic polarizati

ISSN:0021-9304    

DOI:10.1002/jbm.820120409

出版商:John Wiley&Sons, Inc.    

年代:1978

数据来源: WILEY

摘要:

AbstractTo determine whether progressive infection along percutaneous conduits (PC) usually leads to infection of cardiac assist devices, two PCs each were implanted into the subcutis of 11 dogs. One month later, one end of one conduit was inoculated with eitherE. coliorS. aureus. The resulting infections in all dogs progressed little during the first two weeks and in 10 of the 11 animals involved less than 40% of the total length of the PC. Bacteriological tests one month after the infecting organisms were introduced showed that they were no longer present at the site of inoculation in 4 of the 11 dogs and no bacteria were found at the opposite end of the inoculated PCs or in the noninoculated PCs. Histological observations confirmed these results and indicated that in all animals encapsulation of the infected area prevented its further enlargement.

ISSN:0021-9304    

DOI:10.1002/jbm.820120410

出版商:John Wiley&Sons, Inc.    

年代:1978

数据来源: WILEY

摘要:

AbstractA method is shown by which to identify wear particles of implanted plastic materials in tissue. A Mettler FP2 hot stage was used to determine the melting point of different elastomer particles in normal histological sections between the crossed nicols. By using a microcolorimeter Type MPE (Leitz, Wetzlar, Germany), additional information about the molecular degradation of wear particles was obtained.

ISSN:0021-9304    

DOI:10.1002/jbm.820120411

出版商:John Wiley&Sons, Inc.    

年代:1978

数据来源: WILEY