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Biomedical subjects

M Wakasugi

Publications and source records attributed to M Wakasugi.

42 records · Page 3Linked to original sources
PubMed1989

The effects of sex hormones on the synthesis of prostacyclin (PGI2) by vascular tissues.

The effects of estradiol and testosterone on prostacyclin (PGI2) release (measured as 6-keto-PGF1 alpha) by vascular tissues using rat aortic rings and cultured rabbit aortic smooth muscle cells (SMC) were investigated. Aortic SMC were prepared from either explants of atherosclerotic intima or those of normal media. Aortic rings obtained from male and female rats which had been treated with estradiol resulted in increased PGI2 synthesis. Furthermore, PGI2 synthesis by cultured medial SMC was significantly increased in the presence of estradiol (10(-7), 10(-9) M). An increased tendency in PGI2 synthesis was also observed in intimal SMC. On the other hand, aortic rings obtained from female rats treated with testosterone resulted in a significant decrease in PGI2 synthesis. However, aortic rings from testosterone-treated male rats and cultured medial and intimal SMC treated with testosterone (10(-6), 10(-8) M) for 48 hr did not show any significant changes in PGI2 synthesis. We also found greater PGI2 synthesis by intimal SMC compared with that by medial SMC. These results suggest that estradiol and testosterone may have opposite functions in the development of atherosclerosis, that is, estradiol for anti-atherosclerotic and testosterone for atherogenic, by modulating PGI2 synthesis by vascular tissues.

Animals↗
PubMed1989

Effect of insulin on the production of prostacyclin and cell proliferation in cultured smooth muscle cells.

We have investigated the effects of insulin on the synthesis of prostacyclin and cell proliferation in cultured vascular smooth muscle cells, which have been thought to play important roles in the development of atherosclerosis. Prostacyclin was measured as 6-keto-PGF1 alpha in the culture medium, and cell proliferation as incorporation of [3H]thymidine into DNA. Our studies showed that insulin reduced production of prostacyclin and stimulated cell proliferation in SMC. Like insulin, dibutyryl cAMP inhibited the production of prostacyclin, whereas it did not stimulate cell proliferation. No significant changes in cAMP levels were found on the addition of insulin into the culture medium. Therefore, cAMP does not appear to be involved in the mechanisms of these insulin effects. These results again suggest that hyperinsulinemia could be one of the important factors in atherosclerosis.

1-Methyl-3-isobutylxanthine↗
PubMed1988

Increased production of prostacyclin (PGI2) by vascular intimal smooth muscle cells from atherosclerotic rabbit aorta.

In vitro PGI2 synthesis by aortic strips obtained from thoracic aorta of rabbits fed a high cholesterol diet was examined and compared with that of control rabbits fed a normal diet. In this report, the amounts of PGI2 produced were shown as 6-keto-PGF1 alpha per microgram of aortic tissue DNA instead of per mg wet weight. We also investigated PGI2 synthesis by cultured smooth muscle cells (SMC) obtained from atherosclerotic intima. Basal PGI2 production by aortic strips from atherosclerotic rabbit aorta was significantly augmented compared with that of controls. Arachidonic acid (AA)-induced PGI2 production by atherosclerotic aorta was also significantly higher than that of controls. PGI2 producing capacities of intimal and medial layers, separated from atherosclerotic aorta, were examined and the intimal layer was found to elicit a significantly greater PGI2 production than the medial layer. Furthermore, cultured intimal SMC obtained from atherosclerotic rabbit aorta produced a greater amount of PGI2 than medial SMC from normal rabbit aorta at various cultured conditions. These results suggest that the possibility of enhanced PGI2 production by atherosclerotic aorta may well be considered as a defence mechanism of the vessel wall against damaging stimuli.

Animals↗
PubMed1981

Differences between ceftizoxime and its stereoisomer in antibacterial activity and affinity for penicillin-binding proteins.

A new cephalosporin derivative, ceftizoxime (syn FK 749), and its anti isomer, FR 14060, were compared in antibacterial activity, outer membrane permeability, stability to beta-lactamases, and affinity for penicillin-binding proteins (PBPs), using Escherichia coli NIHJ JC-2 and Enterobacter cloacae 58-5 as the test organisms. Although ceftizoxime was superior in antibacterial activity to FR 14060, no marked differences between the two agents were found in outer membrane permeability and stability to cephalosporinase. However, the affinity for PBPs and stability to penicillinase of ceftizoxime and FR 14060 differed significantly. Concentrations of ceftizoxime required to reduce [14C]penicillin G binding by 50% were below 1 microgram/ml for PBPs 1a and 1bs of E. cloacae 58-5 and below 3.2 microgram/ml for PBPs 1a and 1bs of E. coli NIHJ JC-2. A more than 10-fold-higher concentration of FR 14060 was required for 50% reduction of (14C]penicillin G binding to PBP 1bs of strains tested. Ceftizoxime was severalfold more stable than FR 14060 to penicillinase, but the antibacterial activity of both drugs against penicillinase-producing E. coli was as strong as against non-penicillinase-producing E. coli. These results indicate that the difference between the two compounds in antibacterial activity is likely to be due to differences in their abilities to inhibit peptidoglycan polymerization.

Bacteria↗