摘要:

AbstractIn order to further the understanding of protein‐surface interactions in the coagulation system, we have chosen to study plasma protein adsorption onto heparin immobilized surfaces. Heparin‐binding proteins are abundant in plasma: a search of amino acid sequences revealed that many plasma proteins have possible heparin binding sites. Plasma protein adsorption to the heparinized surfaces is monitored by a novel technique in which the solution depletion of proteins is analytically determined using quantitative two‐dimensional polyacrylamide gel electrophoresis (2‐D PAGE). This method enables simultaneous, quantitative detection of the majority of plasma proteins before, during, and after their adsorption onto high surface area adsorbents. Using computerized densitometry of silverstained 2‐D PAGE gels, the amount of each protein can be determined from the integrated optical density of each protein “spot.” Kinetics of adsorption and adsorption isotherms of four important heparin binding proteins, antithrombin III (ATIII), complement factor C3 (C3), apolipoprotein AI (Apo‐AI) and apolipoprotein AIV (Apo‐AIV) are reported in this paper. From the adsorption isotherms, the apparent binding constants of each protein‐immobilized heparin complex,Ka, were calculated. The surface binding constants were of the same order of magnitude as the respective solution binding constants in the literature. The surface binding constants followed the same order as the respective solution binding constants:Ka(ATIII)>Ka(Apo‐AIV)>Ka(C3)>Ka(Apo‐AI), indicating that protein binding to the immobilized heparin used is not essentially differen

ISSN:0021-9304    

DOI:10.1002/jbm.820250402

出版商:John Wiley&Sons, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractCell culture techniques were used to determine the source of cytotoxic agents in a commercial BIS‐GMA composite. The material was polymerized according to the manufacturer′s directions and leachable components were removed by room temperature extraction in ethanol, chloroform, or toluene. The leachable components in the extracts were identified using infrared spectrographic analysis. Thin layer chromatographic analysis was used to determine the number of constituents. These constituents were separated by gas chromatography and then identified by mass spectrographic analysis. Succinic dehydrogenase activity and radioactive labeling with tritiated leucine were used to evaluate cell metabolism and protein synthesis, respectively. The infrared analysis of the extracts showed that the primary component was unreacted BIS‐GMA. Trace amounts of 2‐hydroxy‐4‐methoxy‐benzophenone, a light stabilizer, as well as a phenyl ester of benzoic acid which was probably degraded from BIS‐GMA, were detected by the mass spectrographic method. The removal of leachable components caused a 90% decrease in toxicity compared to the nonextracted BIS‐GMA samples. The extracted BIS‐GMA samples showed no cellular response compared to the Tefl

ISSN:0021-9304    

DOI:10.1002/jbm.820250403

出版商:John Wiley&Sons, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractThe nature and mechanism of calcium complexation with human serum components in the presence of silicone rubber were assessed inin vitromodel experiments. Silicone rubber samples were incubated for 67 h in serum of both physiologic calcium concentrations and induced hypercalcemic levels. Physiologic calcium incubation decreased the intrinsic andnth binding site association constants by factors of 2 and 4, respectively, from initial serum values. Incubation with silicone rubber did not change the association constants. Hypercalcemia incubation lowered the intrinsic andnth binding site association constants by 39 and 61%, respectively. Polymer incubation increased the intrinsic association constant and decreased the number of binding sites by a factor of 2. With initial binding site association constants unperturbed by incubation and Hill coefficients equivalent to 1, complexation was noncooperative and binding sites were considered to be identical and independent. Both Scatchard and Hill plots show nonlinearity for the polymer incubation case giving two distinct linear regions. This is indicative of cooperative binding for incubation with polymer; the Hill coefficient for the physiologic calcium concentration range was 0.97, while the coefficient for the hypercalcemic calcium range was 6.

ISSN:0021-9304    

DOI:10.1002/jbm.820250404

出版商:John Wiley&Sons, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractBone remodeling around three different endossesous dental implant designs placed in dog mandibles was studied using radiography during lengthy periods of function and by histology after animal sacrifice. The three designs investigated were (a) threaded (c.p. titanium), (b) fully porous‐coated (titanium alloy), and (c) partially porous‐coated (titanium alloy). The implants were kept in function for either 32 weeks (fully porous‐coated) or 73 to 77 weeks (partially porous‐coated and threaded). The studies indicated that some crestal bone loss occurred for both the threaded and partially porous‐coated implants while no significant bone loss was seen with fully porous‐coated implants in the absence of plaque‐associated infection. It is suggested that these observed differences are a result of the different stress states that develop in bone surrounding the three designs underlying the importance of implant design on bo

ISSN:0021-9304    

DOI:10.1002/jbm.820250405

出版商:John Wiley&Sons, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractA calcium phosphate cement, Grossman sealer, and Sargenti N2 were compared under conditions where root canals of monkey incisors were deliberately overfilled and the apical tissue responses were evaluated histologically. The periapical tissues exposed to Sargenti N2 revealed severe irritation at all times through the 6‐month experimental period. The reactions to Grossman sealer were milder but persisted throughout the observation period. The calcium‐phosphate‐cement treated animals showed mild tissue irritation after 1 month, but thereafter the adverse tissue reactions were minimal. New bone formation adjacent to the cement was also observed. These results point to the possibility that calcium phosphate cement might be used in simplified endodontic procedures. The compatibility of calcium phosphate cement with the periapical tissue suggests that the cement may have other applications in dentistry and med

ISSN:0021-9304    

DOI:10.1002/jbm.820250406

出版商:John Wiley&Sons, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractAmong 212 vascular prostheses collected in a cascular explant retrival programe, 50 exhibited one or more criteria of graft infection i.e., (a) clinical evidence of graft infection, (b) positive bacteriological analyses of the graft, and (c) presence at the blood‐prosthetic interface of characterized microorganisms. Whereas each of these criteria was noted respectively in 25, 26, and 20 cases, there was no complete overlapping among the three criteria, but their combination led us to consider 50 cases of infected vascular grafts among the 212 collected. These results, and the occurrence in two cases among six investigations for viral infection, suggest that extensive bacteriological investigations of cascular explanted should be inculded in an implant retrieval program, and that infection may represent a high risk in graft failur

ISSN:0021-9304    

DOI:10.1002/jbm.820250407

出版商:John Wiley&Sons, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractWe have previously studied a large number of histological specimens of biomaterials and found that regions with and without an intervening fibrous membrane coexisted in many specimens. Therefore, it appears necessary to perform an evaluation of the entire specimen when histologically assessing the affinity of bone for a biomaterial. Accordingly, we performed a quantitative histological evaluation of hydroxyapatite (HAP)‐ and titanium‐ oxide(TiO2)‐coated Ti‐6Al‐4V and uncoated Ti‐6Al‐4V (control) by determining the affinity index. This was defined as the length of bone directly opposed to the implant/the total length of the bone‐‐implant interface X 100%. The test materials were inserted into the distal epiphyseal region of the femurs of adult dogs, and follow‐up quantitative histological comparisons were performed from 4 weeks to 96 weeks. The HAP‐coated implants had the highest affinity index 4 weeks after insertion, and this superiority was maintained up to 96 weeks. There was a significant difference in affinity index between HAP‐coated implants and control implants (P<0.001), while TiO2‐coated implants showed no significant difference in

ISSN:0021-9304    

DOI:10.1002/jbm.820250408

出版商:John Wiley&Sons, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractThe effect of an endothelial cell (EC) lining on intimal hyperplasia at the distal anastomosis of Dacron grafts was assessed in a canine model. Enzymatically derived autologous EC were used to seed 14 to 17 cm long, 4 mm I.D., knitted Dacron aortoiliac grafts implanted in an end‐to‐side manner in six dogs (Group I). Unseeded grafts were similarly implanted in six control dogs (Group II). All animals received acetylsalicylic acid (325 mg po qd) 24 h prior to graft placement and for 2 weeks postoperatively. Distal anastomotic intimal hyperplasia (AIH) and luminal surface EC coverage were quantitated at the conclusion of a 16‐week study period. Patency for Group I and Group II grafts were 90% and 55%, respectively (p= 0.07). Maximum AIH, defined as the maximum reduction of luminal cross‐sectional area at the distal anastomosis, was not significantly different between Group I (13.1 ± 8.0%) and Group II (15.1 ± 7.3%) conduits. However, AIH was inversely related to the extent of luminal EC coverage (r= −0.6,p<0.05), thus greater endothelialization was associated with decreased AIH. These data support the idea that EC coverage of the luminal surface of prosthetic vascular grafts may limit the develop

ISSN:0021-9304    

DOI:10.1002/jbm.820250409

出版商:John Wiley&Sons, Inc.    

年代:1991

数据来源: WILEY

摘要:

AbstractResidence‐time‐dependent changes in fibrinogen after its adsorption to Biomer were examined by measuring platelet adhesion and antibody binding to the adsorbed protein, and the amount of adsorbed fibrinogen which could be eluted by sodium dodecyl sulfate (SDS). Baboon fibrinogen was first adsorbed (from either pure solution or dilute plasma) to Biomer, which was then stored in either buffer or buffered albumin solution prior to testing. Subsequently, the adherent protein layer was either probed for fibrinogen capable of mediating platelet adhesion using111In radiolabeled, washed platelet suspensions under both static and shearing conditions, or for fibrinogen capable of binding antibody using a direct enzyme linked immunosorbent assay (ELISA). Alternatively, the surface with the adsorbed protein layer was soaked in a 3% SDS solution, and the amount of125I radiolabeled fibrinogen retained was measured. Decreases in platelet and antibody binding, and in the SDS elutability of the adsorbed fibrinogen after it was stored in buffer were detected, although different rates of decrease were observed for each method. When the protein‐coated surfaces were stored in buffered albumin solution rather than buffer, the decrease in the reactivity of fibrinogen was prevented. While each of the three assays measures a different property of adsorbed fibrinogen, this study suggests that the adherent protein undergoes time dependent conformational changes which render it less reactive toward platelets and antibodies, and more resistant to elution b

ISSN:0021-9304    

DOI:10.1002/jbm.820250410

出版商:John Wiley&Sons, Inc.    

年代:1991

数据来源: WILEY

ISSN:0021-9304    

DOI:10.1002/jbm.820250411

出版商:John Wiley&Sons, Inc.    

年代:1991

数据来源: WILEY