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Biomedical subjects

Y Sakamoto

Publications and source records attributed to Y Sakamoto.

At least 721 records · Page 40Linked to original sources
PubMed1981

Relative contributions of sulfur atoms of dietary cysteine and methionine to rat liver glutathione and proteins.

The relative contributions of sulfur atoms of dietary L-Cys and L-Met to the syntheses of proteins and GSH in rat liver were examined. 1) When the amount of sulfur-containing amino acids in L-Trp-deficient diets was fixed at 0.36%, incorporation of L-[35S]Cys into GSH was proportional to the amount of L-Cys administered, in the presence of L-Met in the diet. Incorporation of 35S from L-Met into GSH was lower than that from the same amount of L-Cys and became negligible in the presence of a large amount of L-Cys. 2) When rats were given L-Trp-deficient diet, more L-Cys was always incorporated into liver GSH than into proteins. But, when rats were given L-Trp-fortified diet containing more L-Met than L-Cys, more L-Cys was incorporated into liver proteins than into GSH. 3) Met-sulfur was preferentially incorporated into liver proteins with or without L-Trp. Its absolute incorporation into proteins was significantly greater in the presence of L-Trp than in its absence. 4) When the amount of L-Met in the diet was increased from 0.18 to 0.36 or 0.54%, incorporation of Met-sulfur into proteins increased proportionally, in the presence of 0.18% L-Cys. Unexpectedly, incorporation of L-Cys formed from L-Met into liver proteins was larger than that from L-[3H]Met itself. L-Cys formed from L-Met was incorporated into proteins more readily than L-Cys given as such. 5) When the amount of L-Met in the diet was increased from 0.18 to 0.54%, incorporation of Met-35S into GSH increased 8-fold. Even with a large excess of L-Met, L-Cys was invariably incorporated into GSH. 6) These results are consistent with the role of liver GSH as a reservoir of cysteine, as proposed by us.

Animals↗
PubMed1981

Serodiagnosis of type A hepatitis by detection of immunoglobulin M-type antibody to hepatitis A virus.

Serum specimens from 12 patients with type A hepatitis were analyzed for immunoglobulin M-type antibody to hepatitis A virus (IgM anti-HA). A recently developed solid-phase radioimmunoassay kit for IgM anti-HA (HAVAB-M, Abbott Laboratories) and a competitive binding radioimmunoassay kit (HAVAB, Abbott Laboratories) with or without 2-mercaptoethanol treatment, as modified by Yano et al. (Acta Hepatol. Jpn. 21, 704-712, 1980) were used to obtain an M-index. All specimens obtained within 60 days of the onset of illness and specimens from 2 of 4 patients later than 60 days after the onset were positive with the HAVAB-M test. This test gave negative results to sera which were positive for anti-HA by a standard HAVAB test in the following: 3 patients with type B hepatitis; 5 with non-A, non-B hepatitis; 11 healthy adults; and 10 sera strongly positive for rheumatoid factor. The M-index for type A hepatitis in sera within 30 days of the onset (mean value of the M-index, m, = 1.52; standard deviation, SD, = 0.25) was significantly higher than that for non-A hepatitis (m = 1.05; SD = 0.15) and for healthy adults (m = 1.02; SD = 0.10). The simplicity and usefulness of the HAVAB-M test in diagnosis of acute type A hepatitis over those measuring the M-index by HAVAB tests were shown by direct comparison of the results.

Adult↗
PubMed1981

Effect of high level of endogenous corticosterone on glucocorticoid receptors in the spleen of rats bearing AH130 tumors.

Increase in spleen weight and in the number of spleen cells was observed in rats bearing AH130 (solid-type) tumors, which have high plasma corticosterone concentrations. In contrast, decrease in the number of spleen cells was observed in adrenalectomized rats without tumors which were injected every 3 hr with a dose of corticosterone sufficient to produce a plasma level close to the physiological range in rats with advanced stage tumors. In the spleen of adrenalectomized, corticosterone-treated rats, the binding capacity and affinity of cytosol receptors for dexamethasone decreased and were low on day 3 after the last injection of corticosterone, when no corticosterone was detectable in the spleen and the receptors in the liver cytosol showed maximal binding capacity. Neither the level of cytosol receptors in the spleen nor their affinity for dexamethasone, however, were changed in tumor-bearing rats on day 3 after adrenalectomy when the level of cytosol receptors and affinity for steroid of the thymus were still very low. The activity of alanine aminotransferase increased appreciably in the spleen cytosol of glucocorticoid-treated rats, but not in tumor-bearing rats, which have high plasma corticosterone levels. These data show that administration of corticosterone at physiological concentrations affected the spleen cells, the glucocorticoid receptors and alanine aminotransferase, but that in AH130 tumor-bearing rats, which have a high level of endogenous corticosterone, the spleen enlarged without change in the above parameters. Thus spleen cells from rats with tumors were more resistant to glucocorticoid than those from animals without tumors. However, there seemed to be no correlation between the level of glucocorticoid receptors and glucocorticoid resistance.

Adrenal Cortex Neoplasms↗