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Biomedical subjects

K Kojima

Publications and source records attributed to K Kojima.

At least 847 records · Page 47Linked to original sources
PubMed1975

Interaction between polymeric materials and tissue -- biodeterioration of polymeric materials.

Styrene-isoprene block copolymer/methyl methacrylate graft copolymer (SIS-MMA), styrene-butadiene block copolymers (SBS), polyethylene, 1,2-polybutadiene, polysulfone, polycaprolactone polyurethane (PU) and ethylene-vinyl acetate copolymer (EVA) were implanted subcutaneously in dogs for 1 year. The same materials were stored in physiological saline solution at 37 degrees C (in vitro) and in air at room temperature (in air) for 1 year for comparative purpose. Biodeterioration or biodegradation of these materials was studied by mechanical property testing, viscometry, x-ray diffractometry, infrared spectroscopy and microscopy. A little deterioration of the mechanical properties of all the implanted samples was noticed as compared with the samples stored in vitro and in air. The infrared spectrum and x-ray diffraction pattern of the implanted sample except SIS-MMA were practically identical with the control. The implanted samples of SIS-MMA and SBS showed a cracked surface under a differential interference microscope. Viscosity measurements suggested a possible main chain scission for SIS-MMA and cross-linking for SBS and showed that the molecular weight of the other materials was almost unchanged. The intactness was rather surprising in regard to the infrared spectrum and viscosity of PU and EVA, because they were supposed to be more biodegradable. Deterioration of the mechanical properties was not always due to the results of biodegradation, as is often believed, but it must be considered that it might also be due to the absorption of some constituents such as lipids, steroids and amino acid from the body fluids and/or leaching of low molecular weight substances from the implanted materials.

Absorption↗
PubMed1975

Change in electrophoretic mobility of human erythrocyte as the result of membrane shape change in vitro.

Shape change of human erythrocyte due to the membrane externalization induced by incorporation of excess lysolecithin or by hypertonic treatment in vitro, was accompanied by a decrease in the electrophoretic mobility of the cell. No change in sialic acid content of the membrane, mostly responsible for the cell surface charge, was observed in any of these treatments. Therefore, the membrane externalization seems to cause a redistribution of the surface charge and the resulting alteration of the electrophoretic mobility of the cell. Heating at 48 degrees C for 1 hour induced both the shape change and change in the mobility, but at the same time it reduced the membrane sialic acid content.

Cell Membrane↗
PubMed1975

Recent status of organochlorine pesticide residues in foods in Japan.

In Japan, organochlorine compounds, especially BHC, were used in large quantities. Consequently, their accumulation in the human body or in live-stock through feed crops, and the contamination of mother's and cow's milk caused serious public concern. This prompted not only initial stricter regulation of their use but the eventual prohibition of BHC and DDT use in 1971. Fortunately, the contamination of mother's and cow's milk is decreasing by these steps. The Japanese daily BHC intake was 0.57, 0.63 and 1.34 mg./kg. body weight on the average, which is higher than both in England and the United States. But the daily intake of DDT and other organochlorine compounds is the same as or less than in these countries. Two researches in 1971 to 1972 indicate that beta-BHC contained in mother's milk was 0.096 and 0.115 mg./kg. on the average.

Adipose Tissue↗