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Biomedical subjects

Y M Tseng

Publications and source records attributed to Y M Tseng.

5 recordsLinked to original sources
PubMed1989

17-beta-Hydroxysteroid dehydrogenase in rabbit bone marrow.

Because of the general presence of 17-B-hydroxysteroid dehydrogenase (17-B-HSD) in animals and human erythrocytes, it is very likely that this enzyme is also present in the erythrocyte precursor cells in bone marrow. Adult male white New Zealand rabbits were used to demonstrate the existence of the 17-B-HSD in bone marrow cells and to evaluate the biological function of 17-B-HSD in the erythropoietic system in bone marrow. Anemia was artificially induced in these animals in order to stimulate the proliferation of erythropoietic cells. This was accomplished by bleeding or by intra-peritoneal injection of 40 mg/kg of phenylhydrazine. The 17-B-HSD activities were then examined by histochemical and biochemical assays. The results showed a two to three-fold increase of the enzyme activities in both peripheral erythrocytes and bone marrow cells of anemic animals. Our experiments further demonstrate the fine control of erythropoiesis. The enzyme, which favors the conversion of oestradiol to oestrone, is itself boosted by an anemic state. As a result, the inhibitory action of hemopoiesis by oestradiol was relieved.

17-Hydroxysteroid Dehydrogenases↗
PubMed1988

Effect of epidermal growth factor on the sheet formation of the human keratinocyte in cell culture.

Epidermal growth factor is an important element in maintaining keratinocyte proliferation and maturation. To evaluate its effect on keratinocyte growth in vitro, human foreskins were cultured. The epidermal keratinocyte growth in culture was separated into two stages by a conditional medium: the proliferation stage, in which the cells were maintained in a monolayer; and the differentiation stage, in which the cells grew to stratification and keratinization. The keratinocytes were cultured in various concentrations of epidermal growth factor, and their morphology and growth behavior were closely observed. Our results demonstrated that cultured keratinocytes grew in a confluent layer under the influence of epidermal growth factor. In contrast, in a culture without epidermal growth factor, the proliferation rate of cultured keratinocytes slowed down and eventually the cells stopped growing. During serum stimulation, with or without additional exogenous epidermal growth factor, the cultured keratinocytes grew continuously to the normal terminal differentiation. Under this two-stage culture model, the cultured keratinocytes could grow into an intact sheet of graftable epidermis.

Antibodies, Monoclonal↗
PubMed1988

Cytochemical localization and biochemical analysis of the enzyme markers in human hepatoma cell lines.

Three enzyme makers, glucose-6-phosphatase, ATPase and gamma-glutamyl transpeptidase, have been used in studying carcinogenesis of hepatocellular carcinoma. They have been investigated in animal models and human hepatocellular carcinoma in vivo and in vitro. But the inconsistent levels of these three enzymes associated with this type of carcinoma raised the possibility that the carcinoma cells might have derived from the cells originating from different stages of differentiation. To evaluate this possibility, three human cell lines, Hep G2, Hep 3B, and HA 22T, all thought to be arrested in different stages of differentiation based on their biochemical and morphological characteristics, were used as models. The three enzyme markers glucose-6-phosphatase, ATPase and gamma-glutamyl transpeptidase were examined cytochemically and biochemically. Our results showed that there was no correlation between the ATPase levels and the stages of the cell line's differentiation. But both glucose-6-phosphatase and gamma-glutamyl-transpeptidase were higher in cells that were more differentiated.

Adenosine Triphosphatases↗
PubMed1979

Isolation and characterization of yeast nicotinamide adenine dinucleotide kinase.

NAD+ kinase (ATP:NAD+ 2'-phosphotransferase, EC 2.7.1.23) from yeast has been purified utilizing ion-exchange and NAD+-agarose affinity chromatography to give a 2100-fold purification. The apparent homogeneity of the enzyme preparation was confirmed by sodium dodecyl sulfate polyacrylamide gel electrophoresis and analytical ultracentrifugation. The enzyme has a subunit molecular weight of 31,000, and a native molecular weight of 124,000, and is, thus, probably a tetramer. The single form of the enzyme has an apparent isoelectric point of 5.85. Initial velocity studies in the forward direction with both substrates gave intersecting Lineweaver-Burk plots, and this suggests a sequential mechanism in which both substrates are bound before products are released. Replots of these data were linear and gave Km values for NAD+ and ATP of 0.68 mM and 2.3 mM, respectively.

Kinetics↗