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Biomedical subjects

S H Oh

Publications and source records attributed to S H Oh.

At least 145 records · Page 8Linked to original sources
PubMed1981

Ovine and bovine metallothioneins: purification, number of species, zinc content and amino acid composition.

Metallothioneins (MTs) were purified with respect to zinc from tissues of cattle and sheep which had been fed high levels of dietary zinc. These proteins were purified by gel filtration (Sephadex G-75), ion exchange chromatography (twice on DEAE Sephacel) and gel filtration again (Bio-Gel P-10). There is one major and up to three minor MT species in liver, kidney and pancreas from both sheep and cattle. The amount of zinc varies between the different species of MT. Amino acid analyses of the purified preparations revealed a cysteine content of up to 35.7% and the absence of aromatic amino acids for the major species, but the minor proteins contained less cysteine and some aromatic amino acids. The significance of MT in zinc metabolism is discussed.

Amino Acids↗
PubMed1979

Nutritional and environmental factors affecting metallothionein levels.

A number of elements including zinc, cadmium, mercury and copper will enhance the synthesis of MT, but only zinc and cadmium are deposited with this protein at higher levels than with other proteins in the liver when these are given orally. However, mercury and copper are deposited with MT in the kidney regardless of whether given orally or by injection. As the level of zinc is increased in the diet a corresponding increase of zinc concentration occurs only in the MT fraction of tissue cytosols. Zinc disappears from the MT fraction to the supplementation levels within 3 to 4 days when rats which have been fed a high zinc diet are changed to a zinc deficient diet. The evidence indicates that MT is involved with zinc metabolism. The half-life of MT is longer when cadmium is used to induce its synthesis than when zinc is used. Dietary sulfur deficiency limits the synthesis of MT. Various stresses, in which strenuous exercise, cold environment, and CC14 injection were most effective, and infections were found to enhance MT synthesis, suggesting a role for it in the defense mechanism.

Animals↗
PubMed1979

Accumulation and depletion of zinc in chick tissue metallothioneins.

Two experiments were conducted with Hubbard broiler chicks on the metabolism of high levels of dietary zinc. In the first experiment, chicks were fed a basal diet or the basal diet plus 500, 1,000, 2,000 or 4,000 ppm zinc, and in the second experiment chicks were fed the basal diet or the basal diet plus 1,000, 2,000, 4,000, 8,000 or 16,000 ppm zinc, using zinc acetate. Zinc was found to be associated with 4 peaks when the cytosols from tissues (liver, kidney, pancreas and intestinal mucosa) were eluted through columns of G-75 Sephadex. Although the zinc content of all four peaks increased with increased zinc content of the diet, the greatest elevation occurred in metallothionein (MT). This protein was purified from all four tissues (liver, kidney, pancreas and intestinal mucosa) and the amino acid analysis revealed the presence of about 30% cysteine. Zinc accumulated to the greatest extent (microgram in MT/g tissue) in MT of the pancreas. The zinc in MT disappeared very rapidly when chicks which had been fed a diet containing high levels of zinc were fed a low zinc diet, indicating the extreme lability of this metal in this protein. The results suggest the involvement of MT in zinc homeostasis.

Amino Acids↗
PubMed1978

Biological function of metallothionein-IV. Biosynthesis and degradation of liver and kidney metallothionein in rats fed diets containing zinc or cadmium.

The half-lives of liver and kidney metallothionein of rats fed diets containing either 2,000 ppm Zn or 100 ppm Cd were determined by a single injection of 14C-cystine. This protein was purified by Sephadex G-75 and DEAE cellulose column chromatography. Half-lives of liver metallothionein in rats fed the basal (18 ppm Zn), high Zn (2,000 ppm Zn), high Zn then basal, and high Cd (100 ppm) diet were, respectively, 3.4, 2.7 1.3, and 3.3 days, and that of kidney metallothionein were, respectively, 2.0, 2.2, 1.4, and 3.6 days. Thus, Cd-thionein has a longer half-life than Zn-thionein in both liver and kidney. The major species of metallothionein, which were separated on DEAE cellulose, had similar half-lives. Metallothionein, a protein having high content of metals and relatively short half-life, is possibly involved in cellular regulatory function.

Animals↗
PubMed1978

Biological function of metallothionein. V. Its induction in rats by various stresses.

Induction of metallothionein (a Zn-binding protein) was investigated in liver and kidneys of rats under the following stresses: cold environment, hot environment, heat burn, strenuous exercise, and CCl4 intoxication. As markers of metallothionein (MT) synthesis, [14C]cystine and 65Zn were injected parenterally into rats, and MT in liver and kidney supernatants was separated on Sephadex G-75 columns. Among stresses tested, the greatest stimulations of MT synthesis in liver were observed under cold (315%), strenuous exercise (302%), and CCl4 intoxication (543%), as evidenced by increased amount of [14C]cystine and 65Zn incorporation into the MT fraction. In contrast to liver, only small responses were observed in MT synthesis in kidneys. There was a general decline in plasma Zn levels in rats under the stresses employed. However, no great differences were observed in Zn levels in whole liver and kidneys. The present study suggests that various unrelated physiological stresses, which are accompanied with a change in Zn distribution, increase the synthesis of MT in liver of rats.

Animals↗
PubMed1975

Massive polyclonal hyperimmunoglobulinemia E, eosinophilia and increased IgE-bearing lymphocytes.

A patient (E.M.) with marked eosinophilia and hyperimmunoglobulin E (IgE) has been followed for 4 years. Peripheral blood eosinophilia reached levels in excess of 18,000 cells/mm3 and serum IgE concentration increased to more than 210,000 units/ml (about 0.48 mg IgE/ml). The IgE has both lambda and kappa light chains and is therefore considered polyclonal. The patient has an increase in peripheral blood lymphocytes which stain for surface IgE. Transfer of the patient's plasma (plasmsEM) to a rhesus monkey did not induce peripheral boood eosinophilia. The half life of IgEEM in a rhesus monkey was 2.2 days, which is similar to the half life of myeloma IgE in human subjects. The condition was not associated with defined morbidity except for mild persistent pruritus. Various studies revealed no evidence for atopic parasitic, immune deficiency or neoplastic disease.

Adult↗
PubMed1975

In vitro production of IgE by lymphocytes from a patient with hyperimmunoglobulinaemia E, eosinophilia and increased lymphocytes carrying surface IgE.

The peripheral blood lymphocytes of a patient with massive hyperimmunoglobulinaemia E were used for in vitro studies. The serum IgE ranged from 140,000-210,000 u/ml. Peripheral blood lymphocytes had approximately 7% of cells staining for surface IgE. When these cells were cultured in vitro, IgE was produced as measured by the double antibody radioimmunoassay technique. The total IgE produced ranged from 140 to 484 units per 24 hr in different cultures. IgE production was greatest in the first 24 hr of culture and declined progressively thereafter. Some cultures still had measurable IgE at 48 hr. If the lymphocytes staining for surface IgE were the cells producing the IgE, it was estimated that between 1-7 and 2-8 molecules per cell per second were produced. No definite effect of concanavalin A, pokeweed mitogen or phytohaemagglutinin on in vitro IgE production could be demonstrated under the conditions of these experiments.

Cell Fractionation↗