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Biomedical subjects

A Endo

Publications and source records attributed to A Endo.

At least 271 records · Page 15Linked to original sources
PubMed1982

Depside as potent inhibitor of prostaglandin biosynthesis: a new active site model for fatty acid cyclooxygenase.

Forty depsides and depsidones, the esters of phenolcarboxylic acids, were examined for their inhibitory effect against prostaglandin biosynthesis with rabbit renal microsomes. 4-0-Methylcryptochlorophaeic acid was the most active inhibitor so far tested and its IC50 value was 0.34 muM. Kinetic investigation has shown that this depside acts competitively with respect to arachidonic acid as most of the non - steroidal antiinflammatory drugs. X-Ray analysis has revealed that 4-0-methylcryptochlorophaeic acid maintains its rigid conformation by forming a strong hydrogen bond between the hydroxyl and methoxyl groups. Comparison of CPK models between 4-0-methylcryptochlorophaeic acid and non-steroidal antiinflammatory drugs revealed that the carboxyl group and the two rings of these drugs are almost superimposable to those of the depside. This finding led us to propose a new active site model based on the three dimentional structure of the depside.

Animals↗
PubMed1982

A tumor composed of myofibroblasts: an ultrastructural study.

A subcutaneous tumor of the right temporal region of head was removed from an 8-year-old boy. This tumor was studied by light and electron microscopy. He was found to have had a retroperitoneal inflammatory fibrous histiocytoma which had been excised seven years ago. The subcutaneous tumor histologically consisted of spindle cells in fascicles, which did not arrange in a storiform or herring-bone pattern. Electron microscopically, this tumor was chiefly composed od myofibroblasts. electron microscopy is essential to determine the cell types of a tumor and we have classified this tumor as a tumor of myofibroblasts. The relationship between the retroperitoneal tumor and the head tumor was discussed.

Brain Neoplasms↗
PubMed1982

Effect of a glucosyltransferase inhibitor on glucan synthesis and cellular adherence of Streptococcus mutans.

The effects of mutastein, a glucosyltransferase inhibitor derived from an Aspergillus terreus strain, on the glucan synthesis by glucosyltransferases of Streptococcus mutans and sucrose-dependent adherence of S. mutans cells were examined in vitro. The synthesis of insoluble glucan by crude glucosyltransferase of S. mutans strain B13 was markedly inhibited by mutastein at a final concentration of 10 micrograms of protein/ml. The synthesis of insoluble glucan adherent to glass surfaces was almost completely inhibited by mutastein at this concentration. In addition, mutastein inhibited the sucrose-dependent adherence to glass surfaces of resting and growing cells of various S. mutans strains. These results suggest that mutastein could be useful for controlling dental plaque and dental caries in vivo.

Adhesiveness↗
PubMed1981

Isolation and characterization of cells resistant to ML236B (compactin) with increased levels of 3-hydroxy-3-methylglutaryl coenzyme A reductase.

ML236B is a potent competitive inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-CoA reductase) (EC 1.1.1.34), the major regulatory enzyme in cholesterol biosynthesis. This compound inhibits cell growth when present in the culture medium of CHO-K1 cells at a concentration as low as 0.1 micrograms/ml. Addition of the product of the HMG-CoA reductase reaction, mevalonate, to the culture medium prevents the cytotoxic effects of ML236B at a concentration of inhibitor as high as 50 micrograms/ml. Using a stepwise selection procedure, we have obtained two variant cell lines which are resistant to the presence of 8 micrograms/ml of ML236B in the culture medium. The rates of cholesterol synthesis and the cholesterol levels in the variant cell lines, grown in the presence of ML236B, are similar to those of the parental CHO-K1 cell line grown in the absence of inhibitor. Assays of HMG-CoA reductase activity from extracts of variant cells, grown in the presence of inhibitor, reveal that the variant cell lines have an approximately 40-fold higher HMG-CoA reductase activity than does the parental CHO-K1 cell line grown in the absence of inhibitor. However, when the variant cell lines are grown without ML236B in the culture medium, the HMG-CoA reductase activity returns to the parental CHO-K1 level within 5 days, but the resistant phenotype is stable for up to 9 months. We conclude that the variant cell lines are unable to overcome the cytotoxic effects of ML236B by a mechanism which leads to overaccumulation of HMG-CoA reductase which in turn permits normal mevalonate metabolism and cholesterol synthesis to take place.

Animals↗
PubMed1981

Inhibition of brain glutamate decarboxylase by 4,5-dihydroxyisophthalic acid and related compounds.

Hydroxybenzoic and phthalic acids and their related compounds were tested for inhibitory activity to brain glutamate decarboxylase. Of mono-, di-, and trihydroxybenzoic acids, gallic acid was the most inhibitory, giving 50% inhibition at a concentration of 0.17 mM. Dihydroxybenzoic acids were less inhibitory than the trihydroxyacids but more than monohydroxybenzoic acids. Of the phthalic acid-related compounds tested, 4,5-dihydroxyisophthalic acid was the most potent inhibitor, producing 50% inhibition at 0.61 microM. The inhibition of these compounds was competitive with respect to L-glutamate. The Ki values were 0.02, 1.2 and 4.9 microM for 4,5-dihydroxyisophthalic acid, 5-hydroxyisophthalic acid and gallic acid, respectively. When administered intraventricularly to mice, 4,5-dihydroxyisophthalic acid produced a significant decrease in the gamma-aminobutyric acid content of the brain, resulting in induction of convulsions.

Animals↗
PubMed1981

Xanthocillin X monomethyl ether, a potent inhibitor of prostaglandin biosynthesis.

Xanthocillin X monomethyl ether, known as an antiviral antibiotic, was isolated as a potent inhibitor of Dichotomomyces cejpii. The compound inhibited prostaglandin synthesis from 14C-arachidonic acid in rabbit kidney microsomes by 50% at a concentration of 0.2 microM, while prostaglandin synthesis by microsomes of ram seminal vesicle was inhibited by 50% at 20 microM. The inhibition of xanthocillin X monomethyl ether was reversible. Of the enzymatic steps involved in the synthesis of prostaglandins and thromboxanes tested, conversion of arachidonic acid into prostaglandin H2 was specifically inhibited by xanthocillin X monomethyl ether. Anti-inflammatory activity of this antibiotic on carrageenan-induced oedema in the rat foot was, however, not detectable.

Animals↗
PubMed1981

Thielavin A and B, new inhibitors of prostaglandin biosynthesis produced by Thielavia terricola.

Two potent inhibitors of prostaglandin biosynthesis, thielavin A (C31H34O10) and B (C29H30O10), were isolated from cultures of Thielavia terricola. Both of these compounds were shown to be structurally related to depsides, thus consisting of three hydroxybenzoic acid groups. Concentrations required for 50% inhibition of the conversion of 14C-arachidonic acid into prostaglandins F2 alpha plus E2 by microsomes of ram seminal vesicles were 12 microM for thielavin A and 9 microM for thielavin B, respectively. Of the enzymatic steps involved in prostaglandin synthesis, thielavin A specifically inhibited the conversion of arachidonic acid into prostaglandin H2, while prostaglandin E2 synthesis from the endoperoxide was the most sensitive to thielavin B. Thromboxane A2 synthesis from prostaglandin H2 in bovine platelet microsomes were inhibited by 50% at concentrations of 150 and 350 microM of thielavin A and B, respectively. Thielavin B was significantly effective on carrageenan-induced oedema of rats when administered intravenously but on on oral administration. The anti-inflammatory activity was not detectable with thielavin A either on intravenous injection or on oral administration.

Animals↗
PubMed1980

Therapeutic effects of ML-236B in primary hypercholesterolemia.

ML-236B, a competitive inhibitor of 3-hydroxy-3-methylglutaryl CoA reductase, was administered to 11 patients with primary hypercholesterolemia. After 4--8 weeks of drug treatment at doses of 50--150 mg/day, serum cholesterol levels were reduced by 11--37% (27% on average) in cases of heterozygous familial hypercholesterolemia and combined hyperlipidemia. A marked reduction in tuberous xanthomas was noticed in a homozygous case of familial hypercholesterolemia, but here the drug was less effective in reducing the serum cholesterol level and a higher dose was required for treatment. Softening of Achilles tendon xantomas was observed in a case of combined hyperlipidemia.

Adult↗
PubMed1980

Cytogenetic and cytokinetic investigations on lymphocytes from workers occupationally exposed to tetrachloroethylene.

Lymphocytes from 10 factory workers, who had been exposed to tetrachloroethylene for 3 months to 18 years, were examined for possible chromosome aberration, increased sister chromatid exchanges, and modified cell-cycle kinetics. The exposure intensity was such that the workroom air analyses disclosed 92 ppm as a geometric mean in the workshops for Group 1 (6 workers from decreasing workshops), but was in the range of 10 to 40 ppm for Group 2 (4 workers from a support department). Urinalyses for total trichloro-compounds showed 50.7 and 19.0 mg (as trichloroacetic acid)/l as a geometric mean in Group 1 and 2, respectively. cytogenetic and cytokinetic studies did not reveal any significant dose-related changes in chromosome aberrations (either numerical or structural), SCEs rate, the proportion of M2 + M3 metaphases or mitotic index, compared with concurrent controls. Mitomycin C treatment also failed to induce any difference between exposed workers and controls.

Adolescent↗