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Biomedical subjects

K Asai

Publications and source records attributed to K Asai.

At least 271 records · Page 15Linked to original sources
PubMed1984

Ineffectiveness of Ca2+-antagonists nicardipine and diltiazem on experimental atherosclerosis in cholesterol-fed rabbits.

There is accumulating evidence that calcium metabolism plays an important role in the pathogenesis of atherosclerosis. The inhibitory effect of nifedipine, a Ca2-antagonist, on experimental atherosclerosis in cholesterol-fed rabbits has been reported, and we examined the anti-atherosclerotic action of nicardipine and diltiazem, similar Ca2+-antagonists, but no inhibitory action was observed. It is necessary to recognize the fact that the sensitivity of rabbits to an anti-atherogenic diet shows great individual differences. For the purpose of preventing atherosclerosis due to the abnormality of lipid metabolism the use of Ca2+-antagonist is not warranted at the present stage.

Animals↗
PubMed1983

Effect of the calcium blocker, lanthanum, on bovine aortic smooth muscle cells in culture.

Smooth muscle cells harvested from fetal bovine aortic media were grown in subculture in Waymouth medium containing 10% fetal bovine serum for 14 days. Lanthanum (La3+), an inorganic Ca2+- blocker, was added in a concentration of 10(-3) M to the medium. The cultured smooth muscle cells showed short-spindle-shaped or polygonal endothelial cell-like forms, keeping a monolayer of paving-stone pattern and reached the stationary phase. They stayed in a monolayer state until the end of the 14-day culture. By fluorescent staining with FITC-labelled anti-factor VIII serum, the presence of factor VIII antigen, which is regarded as characteristic of endothelial cells in general, was demonstrated. When the medium was changed to the medium not containing La3+, the usual state of smooth muscle cells showing spindle-shaped multilayer proliferation was recovered, therefore demonstrating that this change is reversible.

Animals↗
PubMed1981

New detection and separation method for amino acids by high-performance liquid chromatography.

A simple system for simultaneous fluorescence detection of primary and secondary amines has been developed. The optimum conditions for fluorescing secondary amines in the two-stage reaction technique using sodium hypochlorite and o-phthalaldehyde have been studied, and then the switching flow method (sodium hypochlorite is added only to secondary amines) and the non-switching flow method (sodium hypochlorite is added to all the amino acids) have been compared. It was concluded that the non-switching flow method ensures high efficiency and reliability. This newly-developed system was applied to the detection of amino acids and gave satisfactory results.

Amino Acids↗
PubMed1981

Chemical structure and thermal properties of initiator tRNA from Euphausia sperba in comparison with those of other eucaryotic initiator tRNAs.

The nucleotide sequence of initiator tRNA (tRNAiMet) from Euphausia sperba, which was harvested in the Antarctic Sea, was determined to be pA-G-C-A-G-A-G-U-m1G-m2G-C-G-C-A-G-U-G-G-A-A-G-C-G-U-m2G-C-U-G-G-G-C-C-C-A-U-t6 A-A-C-C-C-A-G-A-G-m7G-U-C-G-G-U-A-G-A-psi-C-G-m1A-A-A-C-U-A-C-U-C-U-C-U-G-C-U-A -C-C-AOH by using post-labeling methods recently developed. The nucleotide sequence was very similar to that of mammalian tRNAiMet except for changes in six bases and three modifications: C16, U55, D47 and m5C48 are replaced by U16, psi 55 and unmodified U47 and C48, respectively. A50-U64 and G52-C62 base pairs of mammalian tRNAiMet are reversed in Euphausia tRNAiMet. In addition, the G49-C65 pair of the former is replaced by a less stable G49-U65 pair in Euphausia tRNAiMet. The sequence homology was compared between Euphausia tRNAiMet and over ten different species of eucaryotic tRNAiMet so far sequenced. The melting temperature of Euphausia tRNAiMet was 72.5 degrees C, which is 4.2 degrees C and 8.3 degrees C lower than those of rat liver and yeast tRNAiMet's, respectively. The origin of the thermal instability of Euphausia tRNAiMet is discussed in comparison of its secondary structure compared with those of other eucaryotic tRNAiMet's.

Animals↗