摘要:

AbstractAs bovine collagen is currently being scrutinized as to its immunogenicity in clinical use, a human source collagen, human amnion collagen (HAC), has been developed in our laboratory as an injectable biomaterial for soft tissue augmentation. Pepsin‐extracted human amnion collagen was highly purified and reconstituted. Gamma irradiation was employed to ensure complete sterility and to produce cross‐linking in collagen chains to improve implant persistence without the use of chemical additives. The purity and characteristics of human amnion collagen were proven by amino acid assay, sodium dodecyl sulfate‐polyacrylamide gel electrophoresis, immune blotting, and collagenase digestion. Animal studies comparing both irradiated and nonirradiated amnion collagen to bovine collagen (Zyderm® and Zyplast®) were carried out in a rat model. Humoral immunity was evaluated by examining the sera for antibody reactivity towards the implanted human collagen by the ELISA test. Insignificant antibody levels against human amnion collagen were found. Animal observation revealed fibroplasia, vascular infiltration, and the development of adipocytes with the implant as well as a lack of inflammatory response following up to 12 months of implantation. The persistence rate of our human amnion collagen was equal to, or even longer than, that of both types of bovine collagen implants. © 1994 John Wiley&S

ISSN:0021-9304    

DOI:10.1002/jbm.820280112

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractStudies were made on the fate of implanted material during bone induction. Mixtures of 1 mg of crude bone morphogenetic protein (BMP), or bovine serum albumin as a control, and 1.5 mg of bovine collagen, were pressed into discs and implanted under the fascia of the rectus abdominus muscle of rats. The tissues with implants were fixed 7, 10, and 14 days later and examined histologically. On day 7 after implantation, the implant was surrounded and invaded by alkaline phosphatasepositive cells. New bone and cartilage were seen at the periphery of the implant. In the regions of calcified cartilage and bone, these osteogenic matrices were intermixed with the implant. The mineral deposits were seen by electron microscopy not only on the osteogenic matrices but also on the implanted collagen. On day 14, the bone had spread to the center of the implant. No osteogenesis or chondrogenesis was seen in control implants. It was concluded that the calcification occurred on the implanted collagen during bone induction, and that it was related to successive bone formation and remodeling. © 1994 John Wiley&Sons, Inc

ISSN:0021-9304    

DOI:10.1002/jbm.820280113

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractCell‐mediated resorption of densely sintered hydroxyapatite (HA1250), tricalcium phosphate (TCP), and 600° or 900°C calcined hydroxyapatite (HA600 and HA900, respectively), was investigated by using two culture systems. The first was an osteoclastic cell culture, and the second was a two‐stage culture that was composed of a bonelike tissue formation on the substrata in the first stage and its subsequent resorption by osteoclasts in the second stage. Neither of the materials showed resorption or surface alterations in the osteoclastic cell culture, except for some limited phagocytotic activity on HA600 and HA900. In the two‐stage culture, production of mineralized extracellular matrix was only observed on HA1250 and TCP, and its subsequent resorption by osteoclastlike cells was evident. Small and occasionally larger tartrate‐resistant acid phosphatase positive cells produced 20–150 μm diameter resorption pits in both the mineralized extracellular matrix on HA1250 and TCP and TCP and the surfaces of HA600 and HA900. Resorption of the mineralized extracellular matrix on TCP also resulted in degradation of the underlying ceramic surface, mainly initiating from intergrain boundaries, whereas the surface of HA1250 remained unaltered. The results of this study clearly demonstrate that osteoclastic resorption of calcium phosphates is potentiated in postosteogenic culture conditions. A possible role for bone matrix constituents in cell‐mediated resorption is hypothesized, whereas the occurrence of resorption seems to be mainly governed by the combined effects of material characteristics such as grain size and crystal structure. © 1994 John

ISSN:0021-9304    

DOI:10.1002/jbm.820280114

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractElectrochemical measurements, x‐ray photoelectron spectroscopy, and scanning tunneling microscopy have been used to study the effect of hydrogen peroxide on the passivity of titanium in a phosphate‐buffered saline (PBS) solution. The results indicate that the passive film formed in the PBS solution—with and without addition of H2O2—may be described with a twolayer structure model. The inner layer has a structure close to TiO2whereas the outer layer consists of hydroxylated compounds. The introduction of H2O2in the PBS solution broadens the hydroxylate‐rich region, probably due to the formation of a Ti(IV)‐H2O2complex. Furthermore, the presence of H2O2results in enhanced dissolution of titanium and a rougher surface on a microscopic scale. Finally, a dark pigmentation (blue color) is observed when titanium has been exposed—for several weeks—to PBS with additions of H2O2. © 1994 John

ISSN:0021-9304    

DOI:10.1002/jbm.820280115

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY

摘要:

AbstractHyaluronan, found in high concentrations in fetal tissues, appears to have a major role in preventing scar formation in fetal wounds. Nevertheless, its role in inhibiting wound contractures associated with scar formation has not been clearly demonstrated. Our current study evaluated the effects of hyaluronan using anin vitrofloating collagen fibrillar matrix (CFM) contraction model. The results demonstrated that the contraction of CFM by fibroblasts was significantly reduced when high concentrations (>1 mg/mL) of hyaluronan were present in the media. This phenomenon is unique to hyaluronan, because chondroitin sulfate was ineffective in this connection. Fibroblast migration and proliferation studies indicated that high concentrations of hyaluronan stimulated cell migration and had no cytotoxic effects.Some possible mechanisms by which high concentrations of hyaluronan reduced CFM contraction by fibroblasts were proposed. Because the viscosity of a hyaluronan solution is much greater than that of chondroitin sulfate, and this increases with concentration, we investigated whether this property in itself was an important factor in inhibiting CFM contraction. No direct correlation was found between the viscosity of glycosaminoglycans and their ability to reduce CFM contraction. © 1994 John Wiley&Sons, Inc

ISSN:0021-9304    

DOI:10.1002/jbm.820280116

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY

ISSN:0021-9304    

DOI:10.1002/jbm.820280117

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY

ISSN:0021-9304    

DOI:10.1002/jbm.820280118

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY

ISSN:0021-9304    

DOI:10.1002/jbm.820280119

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY

ISSN:0021-9304    

DOI:10.1002/jbm.820280101

出版商:John Wiley&Sons, Inc.    

年代:1994

数据来源: WILEY