Hiroko Asahara

Optimum dialysis membrane for endotoxin blocking

Abstract We have reported a novel method of visualizing endotoxin (Et) distribution inside an Et-blocking filtration membrane using both fluorescence-labeled Et and a confocal laser scanning fluorescence microscope (CLSFM) in our previous paper [J. Membr. Sci. 210 (2002) 45]. The objective of the present study is to clarify Et-blocking mechanism of dialysis membranes. Six kinds of dialysis membranes with varying materials (hydrophilic and hydrophobic) and varying structures (pore diameter, skin layer location and thickness, and water content) were evaluated by CLSFM together with other techniques such as atomic force microscopy (AFM). Physicochemical property of a membrane material affects Et-adsorbing efficiency, and further membrane structure affects Et-plugging efficiency. Rejected Et distribution in the membranes with varying materials and structures is successfully visualized using fluorescence-labeled Et by CLSFM. Et adsorption on the membranes occurs first, followed by the narrowing of their pores, and afterward pore plugging is continued. Adsorption plays a vital role in Et-blocking. Double skin layer structure is valid for preventing of Et contamination than only inner skin layer structure because the double skin layer structure blocks Et more farther from blood-side surfaces than the only inner skin layer structure.

Visualization of distribution of endotoxin trapped in an endotoxin-blocking filtration membrane

Abstract Since the finding of β 2 -microglobulin as a causal substance in the carpal tunnel syndrome of chronic hemodialysis patients, removal of β 2 -microglobulin has been performed using highly permeable dialysis membranes with larger pores. Such large-pore membranes tend to allow endotoxins (Et), harmful substances contained in dialysate, to enter blood. At present, as a countermeasure, Et-blocking filtration membranes are used to remove Et from dialysate. However, Et removal mechanism by these membranes has not been clarified yet. The objective of this study is thus to visualize distribution of fluorescence-labeled Et trapped inside the polyester–polymer alloy (PEPA) membrane, a widely used Et-blocking filtration membrane using a confocal laser scanning fluorescence microscope (CLSFM). Et were observed mainly in the outer skin layer of the hollow fiber, while some in the void and inner skin layers. No Et were present inside the hollow fiber. In conclusion, we succeeded in visualization of Et distribution inside the Et-blocking filtration membrane using CLSFM. This novel visualization technique may allow evaluation of distribution of Et trapped inside various kinds of Et-blocking filtration membranes.

The effects of the exercise on reactive oxygen species and redox system in rats

In circulatory diseases like arteriosclerosis, the participation of reactive oxygen species in the disease process was paid to attention. In this research, the effect of the intermittent exercise on the parameters as the risk factors of arteriosclerosis was investigated. Swimming during 1 hour/day was imposed on rats as an exercise for 8 weeks. For the period, changes of HDL, triacylgrycerol, and cholesterol concentrations in blood were measured. In addition, SOD, superoxide, and NOx were measured as an index of the oxidative stress in the heart, the kidney, and the liver. As results, amounts of cholesterol in blood and the blood pressure were decreased by the intermittent exercise. And it was suggested that ..O generation was increased by the increasing of NOx concentration in blood. Therefore, the swim exercise is thought to be effective by the prevention of arteriosclerosis in rats. And it was suggested that the redox system was dynamically affected by the exercise because of the intensely changes of SOD activity and other some parameters with the breeding period and organs.