摘要:

AbstractCylinders (0.8 cm long, 1.0 cm of diameter and with an axial hole), constituted, after firing, of a ceramic mixture of hydroxylapatite (HA) and β‐ricalciumphosphate (β‐TCP) in a 10:1 ratio, were implanted into mid‐diaphiseal defects of one femur of 20 rabbits and stabilized with intramedullary rods. The implantation sites were checked radiographically every month, and after 3 months (3 animals) and 6 months (17 animals) the rabbits were sacrificed and the implants with the surrounding tissue were embedded in methylmetacrylate, cut to thick sections and analyzed by scanning electron microscopy (SEM). Porosimetric and x‐rays diffraction analyses were carried out before and after implantation of the cylinders, and the state of mineralization at the bone–implant interface was determined by EDAX microprobe analysis. Bony callus formation started at 1 month at the osteotomy sites, as judged by radiography, but after 3 months a not‐mineralized zone had still been demonstrated between bone and the implants. At 6 months, 13 implants showed themselves firmly fixed in their implantations beds, while 4 implants were only incorporated at their proximal ends. In bone contact zones, an enrichment of Ca2+was displayed by microanalytical techniques in the outer zone of the implanted samples which may be explained by an apparent additional phase transformation of HA into TCP, thanks to the change of the Ca/P ratio, that takes

ISSN:0021-9304    

DOI:10.1002/jbm.820220602

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe effects of grooved epoxy substrata on epithelial (E) cell behavior were studiedin vitroandin vivo. V‐shaped grooves, 10 μm deep, were produced in silicon wafers by micromachining, a process which was developed for the fabrication of microelectronic components. The grooved substrata were replicated in epoxy resin. More E cells attached to grooved surfaces than to adjacent smooth surfaces. Clusters of E cells were markedly oriented by the grooved surfaces in comparison to the adjacent smooth surfaces where the orientation was random. Grooved and smooth epoxy implants were placed percutaneously in the parietal area of rats. One week after implantation E cells were found to adhere tightly to the implant surfaces. In the grooved portion of the implant E cells interdigitated into the grooves and had rounded nuclei. Histomorphometric measurements indicated that there was a shorter length of epithelial attachment and a longer length of connective tissue attachment in the grooved, compared to the smooth, portion of implants. After 10 days the epithelial attachment had migrated down the length of the protruding smooth portion of the implant and was located on the base of the implant. However, epithelium remained attached to the grooved portion of the implant. These observations indicate that grooved surfaces have the potential to impede epithelial downgrowth on percutaneous devic

ISSN:0021-9304    

DOI:10.1002/jbm.820220603

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractMedical grade silicone rubber has long been considered a suitable meniscal replacement, but there has been increasing concern about migration of this material into adjacent tissues. The objectives of this study were to determine the definitive composition of tissue‐incorporated material which is presumed by light microscopy to be silicone and to identify long term histopathologic sequelae of meniscal replacements. Adult female patients underwent meniscectomy and replacement with silicone rubber (Silastic) implants. After 12 to 18 months, recurrence of symptoms in 8% of these cases led to implant removal with excision of peri‐implant fibrous pseudo‐capsules. Excised tissues, including one preauricular lymph node and implants were submitted for light microscopy, SEM, and energy dispersive x‐ray microanalysis (EDX) for the identification of elemental composition, critical surface tension measurement, and internal reflection infrared spectroscopy. EDX revealed prominent peaks for silicon in both pseudocapsular and nodal tissues. Morphologic findings surrounding the long‐term implants included foreign body reaction, synovitis, dystrophic calcification, fibrocartilaginous metaplasia, hyalinization, and scarring. Particulate silicone debris induced a pathologic response in the tissues and migrated to nodes. These findings suggest that periodic evaluation be performed over the life of such implants to rule out breakdown under function. These findings should intensify the search for improvements or replacements for silicone rubber as an interpositional material in the temporomandibu

ISSN:0021-9304    

DOI:10.1002/jbm.820220604

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractIn vitroadhesion ofStaphylococcus epidermidisto cyanoacrylate tissue adhesive surfaces was investigated by employing a modified Robbins device. Bacterial colonization ofn‐butyl‐2‐cyanoacrylate tissue adhesive polymer surfaces was demonstrated by employing scanning electron microscopy, epifluorescence technique, and aerobic plate counts. TheS. epidermidiswas found to rapidly colonize then‐butyl‐2‐cyanoacrylate polymer surface producing a biofilm composed of embedded bacteria in an extensive amorphous matrix that totally occludes the material surface. The results indicate that the bacteriocidal properties of the polymer to this bacteria are wea

ISSN:0021-9304    

DOI:10.1002/jbm.820220605

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractWe compared two assays for estimating the amount of active heparin bound to a catheter surface: (1) a kinetic assay based on the inactivation of thrombin by antithrombin III, and (2) thrombin uptake. Both assays were used to estimate the amount of heparin activity on a series of catheters coated with no heparin, covalently bound heparin, and ionically bound heparin. The kinetic assay produced estimates of surface‐bound heparin activity and showed that some binding methods resulted in destruction of most of the heparin's biologic activity. In contrast, the thrombin uptake assay did not correlate with the amount of heparin activity on the catheter surface. Substantial thrombin uptake was found on surfaces coated with no heparin or inactive heparin, while low thrombin uptake was found on surfaces with high levels of heparin activity in the kinetic assay. We conclude that: (1) a kinetic assay based on the heparin accelerated inactivation of thrombin by antithrombin III can be used to estimate the amount of active heparin bound to a catheter surface, and (2) thrombin uptake studies do not correlate with heparin activity and do not predict which heparin binding method will result in the highest concentration of active heparin on the catheter surfac

ISSN:0021-9304    

DOI:10.1002/jbm.820220606

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractIn vitrobiodegradation studies were performed to assess the long‐term stability of poly(ether urethane) (PEU) implants. Three PEU's and one poly(ester urethane) were treated with enzymes characteristic of those released from inflammatory cells during the foreign body reaction. In addition, the effect of hydrogen peroxide was observed to examine oxidative degradation. Polymers were prepared as thin films on glass, gold, silver, and copper substrates to test the possibility of metal‐catalyzed degradation. Molecular weights and polydispersities of the polymers were measured by gel permeation chromatography (GPC) before and after treatment. Changes in peak shape and location were also monitored. The results demonstrate that varying degrees of both enzymatic and oxidative degradation occur

ISSN:0021-9304    

DOI:10.1002/jbm.820220607

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractFatigue fracture of artificial implants in the human body, caused by the repeated application of stress, is well documented. It is known that the fatigue strength of implant materials decreases when they are exposed underin vivocorrosion conditions. There are, however, no investigations concerning the effect of body fluids on the fatigue characteristics of commonly used biomaterials. Accordingly, fatigue tests on machined stainless‐steel AISI 316, and COP alloy rods have been conducted in the right lower leg of rabbit. These specimens were piereced through the hole drilled at the middle of the tibial bone. A cyclic tensile stress of frequency 5 or 10 Hz was applied to the rods. From the results, it was found that the fatigue strength at 5 × 106cycles for AISI 316 under thein vivoenvironment was 680 MPa compared to 830 MPa in air and similarly for COP alloy, was 680 MPa in the living body compared to 800 MPa in air. These remarkable changes in fatigue strength associated with thein vivoenvironments are considered to be due to the corrosive action of body fluids on the biomateria

ISSN:0021-9304    

DOI:10.1002/jbm.820220608

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractDensely sintered synthetic hydroxyapatite (HA) is used as an implant material because of its excellent tissue biocompatibility. In order to maximize the biological potential of this calcium phosphate, we have investigated the incorporation of carbonate into HA to make a material which more closely resembles the mineral found in bones and teeth. The aim of the present study was to determine the conditions under which sintered carbonated apatites of specific carbonate content could be produced. The apatites were prepared by heating compressed pellets of precipitated carbonated apatite under a carbon dioxide/steam or nitrogen/steam atmosphere between 825 and 1050°C. The products were analyzed chemically and the surfaces examined by x‐ray diffraction, infrared spectroscopy, reflected light microscopy, and scanning electron microscopy. The results showed that carbonate loss during sintering could be reliably predicted, making it possible to produce materials with specific carbonate content, and with specific physical and chemical compositi

ISSN:0021-9304    

DOI:10.1002/jbm.820220609

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractA series of poly(2‐hydroxyethyl methacrylate)/polyamine graft copolymers (HA copolymers) were examined as an adsorbent for cellular adsorption chromatography in order to separate cell populations with high efficacy. The capability of each copolymer sample to selectively adsorb rat lymphocyte subpopulations (B‐cells and T‐cells) was evaluated by applying a lymphocyte suspension to a copolymer‐coated glass bead column. A separation factor (AB/AT) greater than 5.0 was achieved for the HA copolymer, compared to 1.9 and 1.1 for homopolymers of poly(2‐hydroxyethyl methacrylate) and of a polyamine (poly(N,N‐diethylaminoethylstyrene)), respectively. By loading a rat lymphocyte suspension containing B‐cells (28%) and T‐cells (72%) through the HA copolymer column, more than 60% of T‐cells in 90% purity or more were recovere

ISSN:0021-9304    

DOI:10.1002/jbm.820220610

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractA preliminary study was conducted to demonstrate the usefulness of the combined technique of differential scanning calorimetry (DSC) and mechanical testing for the shape memory metals of 54NiTi and 53NiTiCo(3%) alloys. The DSC technique was used to measure precise transformation temperatures and the amount of thermal energy required for the corresponding phase transformation. The degree of plastic deformation by bending and the effect of alloying (such as Co) were studied with combined DSC and mechanical property measurements.

ISSN:0021-9304    

DOI:10.1002/jbm.820220611

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY