摘要:

AbstractThe growth and morphology as well as collagen biosynthesis of human fibroblasts obtained and cultured on sepiolite–collagen complexes have been studied. No differences on cell morphology and growth properties nor collagen synthesis were observed when compared with standard culture substrates. The type I/type III ratio of biosynthesized collagen by fibroblasts cultured on sepiolite–collagen complexes was about 5–6 with no difference when compared to control conditions. This normal behavior was also observed for the type I/type III procollagens. According to these studies the sepiolite–collagen complexes do not modify the studied features of the fibr

ISSN:0021-9304    

DOI:10.1002/jbm.820220402

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractThe role that substrate surface properties play in influencing the extent of endothelialization of polymer surfaces has been investigated. For a wide range of polymer surfaces, the degree of endothelialization cells is directly related to polymer surface tension: increased endothelialization occurring with increasing substrate surface tension. As a result of adsorption of the proteins in the culture media, the surface properties of the polymers are altered considerably. The protein‐coated polymers were characterized by means of liquid–liquid contact angle measurements under non‐denaturing conditions. A striking correlation is observed between the degree of endothelialization and the measured dextran contact angle. The degree of endothelial cell spreading is not related to polymer surface tension. Cell morphology and extracellular matrix production, however, are influenced by substrate surface prope

ISSN:0021-9304    

DOI:10.1002/jbm.820220403

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractPorous coated Ti‐6Al‐4V alloy implant systems provide a biocompatible interface between implant and bone, resulting in firm fixation and potential long‐term retention via bony ingrowth. In order to achieve an acceptable porous coating structure, the sintering protocol for Ti‐6Al‐4V alloy systems often requires that the material be heat treated above the beta transus. This transforms the as‐received equiaxed microstructure, recommended for surgical implants, to a lamellar alpha‐beta distribution, which has been shown to have the worst fatigue properties of the most common structures attainable in Ti‐6Al‐4V alloy. However, post‐sintering heat treatments may be used to improve these properties by producing microstructures more resistant to crack initiation and propagation. This study investigated the influence of microstructural variations on the fatigue properties of porous coated Ti‐6Al‐4V alloy material. Nonporous coated and porous coated Ti‐6Al‐4V alloy fatigue specimens were subjected to a standard sintering heat treatment to produce a lamellar microstructure. In addition, two post‐sintering heat treatments were used to produce coarse and fine acicular microstructures. Rotating beam (reversed bending) fatigue testing was performed and the endurance limits determined for the noncoated and porous coated microstructures. The values determined were 668 MPa (noncoated asreceived equiaxed), 394 MPa (noncoated lamellar), 488 MPa (non‐coated coarse acicular), 494 MPa (noncoated fine acicular), 140 MPa (porous coated lamellar), 161 MPa (porous coated coarse acicular), and 162 MPa (porous coated fine acicular). The noncoated coarse and fine acicular specimens displayed an approximate 25% increase over the noncoated lamellar specimens. The porous coated coarse and fine acicular specimens showed an approximate 15% improvement over the p

ISSN:0021-9304    

DOI:10.1002/jbm.820220404

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractFerromagnetic alloys, used in the form of „thermoseeds”︁ for surgical implantation, have been developed and used to induce localized hyperthermia in cancerous growths. Alloys of nickel with approx. 4 wt.% Si were chosen for this study because they have Curie temperatures in the desired range of 45–60°C. The thermoseeds were prepared by using either a special casting technique or casting and swaging followed by homogenization. The effects of these different processing schedules on the magnetic behavior of these alloys are discussed. In particular, the importance of minimizing oxidation during melting and heat treating, and the effects of homogenizing the thermoseeds on the relative permeability at temperatures near the Curie temperature are pointed out. The best processing schedule is casting small ingots while avoiding oxidation, followed by swaging, drawing, and homogenization. Actual induction heating experiments and the results from magnetization tests indicate that Ni‐4 wt.% Si alloys prepared in this manner can be used as thermoseeds with predictable Curie temperatures. These thermoseeds can be used to obtain nearly uniform and constant temperatures in tumors with variable b

ISSN:0021-9304    

DOI:10.1002/jbm.820220405

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractA series of experiments was conducted to studyin vitroandin vivometal ion release and the urine excretion of metal ions. Metal salts were injected and urine analyzed. Anodic potentials were applied to stainless steel and cobalt‐chromium‐molybdenum (CCM) specimens to cause an acceleration of corrosion rates. Corrosion experiments were done in saline, 10% serum and in a subcutaneous space in hamsters. Corrosion rates were determined by measurements of weight loss and calculations of net charge transfer. Metal ion concentrations were determined with graphite furnace atomic absorption spectroscopy, and were calculated from total charge using Faraday's law. The results with stainless steel showed that the weight loss and metal ion release from stainless steelin vitroandin vivocan be calculated using Faraday's Law, assuming release in proportion to alloy composition. The results with CCM indicated that release ratesin vitrocan be used to determine the proportionality of releasein vivo. All the nickel and most of the cobalt was rapidly excreted, while less than 50% of the chromium was excreted. The excretion of metals following salt injection orin vivocorrosion were very simi

ISSN:0021-9304    

DOI:10.1002/jbm.820220406

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

摘要:

AbstractIn order to investigate the interactions of cellular elements and protein on constantly deforming (fatiguing) blood contact surfaces, a series ofex vivocanine arteriovenous shunt experiments were conducted. While fresh blood was flowing through Silastic tubing shunts, portions of the tubing were stretched 20 to 60% at a frequency of 20 to 90 cycles per minute for 10 to 90 min. The surfaces of the tubing that were stretched were compared with control tubing surfaces taken from the arterial side of the test segment using scanning electron microscopy and interference phase contrast microscopy.Approximately the same number of platelets were deposited on the stretched as on the unstretched portions of the tubing in the ten minute experiments. On the control portions of the tubing, the platelets were deposited singly and uniformly in what appeared to be a fairly inactivated state. On the stretched tubing, more pseudopod extension and aggregation was observed. In these preliminary experiments, no differences were noted as a function of frequency of stretch. As the blood contact time and the percent stretch were increased, only nonuniform, scattered aggregations of platelets, and platelets mingled with fibrin were seen. Significant numbers of spread white blood cells were observed on many of the segments of Silastic tubing stretched 20% for as short a time as 15 min. Granulocytes have occasionally been reported on less hemocompatible biomaterials after exposure to canine blood. This helps to confirm that substrate stretching of 20–60% had an adverse effect on the blood compatibility of the Siliastic tubin

ISSN:0021-9304    

DOI:10.1002/jbm.820220407

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

ISSN:0021-9304    

DOI:10.1002/jbm.820220408

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY

ISSN:0021-9304    

DOI:10.1002/jbm.820220401

出版商:John Wiley&Sons, Inc.    

年代:1988

数据来源: WILEY