No abstract

Oxygen radicals have recently been attracting close attention because of their involvement in tissue damage and their close relationship to various clinical conditions. It has been suggested that hemodialysis increases oxidative stress, triggering the development of complications such as atherosclerosis and dialysis-related amyloidosis. We recently developed a dialyzer containing a highly functional polysulfone membrane on which vitamin E had been bonded (PS-ViE). The present study was undertaken to evaluate the biocompatibility of this membrane and to conduct other experiments on the membrane in vitro. Human blood was dialyzed with minidialyzers (300-600 cm(2) membrane area) made of PS-ViE, cellulose, or untreated polusulfone (PS), and the effects of the dialyzers on complements (C3a, C4a, and C5a), cytokines (IL-1beta and IL-8), and granulocyte elastase as well as their anti-oxidative activity were investigated (n = 6). The effect of PS-ViE on complement activation and its effects on cytokines were comparable to those of PS membrane, whereas granulocyte elastase following dialysis with the PS-ViE membrane tended to be lower than that seen with PS membrane. The effects of PS-ViE-induced methemoglobin, lipid peroxide, and oxygen radicals were significantly less than those of PS membrane, indicating the antioxidative activity of PS-ViE. Vitamin E-modified polysulfone membrane dialyzers were found to have favorable effects on the immune system and to express antithrombotic and antioxidative effects.

No abstract

The JMM-ZTA, a kind of zirconia-toughened alumina, is a bearing ceramic newly developed for artificial joints. Although it has already been reported that mechanical strength and fracture toughness are higher in the JMM-ZTA than in alumina, the stability of the JMM-ZTA has not been studied in detail yet. In the present study, the stability of the JMM-ZTA with respect to mechanical strength and crystalline phases was examined under hydrothermal environment, and the results were compared with those of alumina. Both the 4-point bending strength and the fraction of monoclinic zirconia unchanged even after the aging test at 121°C for 300 h. These results indicate that the JMM-ZTA possesses quite excellent stability to be used as bearing material of artificial joints.

There has been a demand for hemodialysis membranes of better biocompatibility, the use of which would reduce the incidence of complications in patients who have been under long hemodialysis treatment. We developed a surface modification technique consisting of forming efficiently a synthetic polymer layer on the inside of the regenerated cellulose hollow fiber without impairing fiber performance. Our newly developed membrane has excellent biocompatibility by modifying the inner surface and by immobilizing vitamin E (alpha-tocopherol), which serves as an antioxidant, to the modified surface.