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Biomedical subjects

C S Tsai

Publications and source records attributed to C S Tsai.

14 recordsLinked to original sources
PubMed1992

Enzyme activities of D-glucose metabolism in the fission yeast Schizosaccharomyces pombe.

The activities of key enzymes that are members of D-glucose metabolic pathways in Schizosaccharomyces pombe undergoing respirative, respirofermentative, and fermentative metabolisms are monitored. The steady-state activities of glycolytic enzymes, except phosphofructokinase, decrease with a reduced efficiency in D-glucose utilization by yeast continuous culture. On the other hand, the enzymic activities of pentose monophosphate pathway reach the maximum when the cell mass production of the cultures is optimum. Enzymes of tricarboxylate cycle exhibit the maximum activities at approximately the washout rate. The steady-state activity of pyruvate dehydrogenase complex increases rapidly when D-glucose is efficiently utilized. By comparison, the activity of pyruvate decarboxylase begins to increase only when ethanol production occurs. Depletion of dissolved oxygen suppresses the activity of pyruvate dehydrogenase complex but facilitates that of pyruvate decarboxylase. Acetate greatly enhances the acetyl CoA synthetase activity. Similarly, ethanol stimulates alcohol dehydrogenase and aldehyde dehydrogenase activities. Evidence for the existence of alcohol dehydrogenase isozymes in the fission yeast is presented.

Cell Division↗
PubMed1992

[The pattern of fresh frozen plasma transfusion in Veterans General Hospital-Taichung].

Conducted a survey at Veterans General Hospital in Taichung, to compile a statistical analysis on the usage of fresh frozen plasma (FFP) transfusions. The investigation was conducted from July 1st to September 30, 1991. According to the distribution of usage of FFP, we investigated 726 transfusions (4,216 units) based on our grouping criteria. We found the following: 532 units were used for clotting support which accounts for 12.6% of total, 815 units (19.3%) for blood pressure support, 148 units (3.5%) for combination of clotting and blood pressure support, 681 units (16.2%) for albumin replacement, 436 units (10.3%) for therapeutic pheresis, 396 units (9.4%) for packed red cell concurrently, 819 units (19.4%) for burn cases, and the remaining (9.2%) for other or unidentified reasons. If it was classified by the departments applying FFP; 76% (3,200 units) were used by surgery, 22.4% (947 units) by internal medicine, and 1.6% (69 units) by other departments. Having classified all the reasons for FFP transfusion, we found that FFP was commonly used as a volume expander, for nutrition support, and reconstituted whole blood. These reasons are out of the range of indications for FFP transfusion. This misuse of FFP transfusion increases the chance of transmission infections therefore, we will thoroughly investigate these treatment modalities in order to ensure our blood source is being used in an appropriate manner. This will allow patients the best possible treatment available.

Adolescent↗
PubMed1978

Kinetic and mechanistic studies of methylated liver alcohol dehydrogenase.

Reductive methylation of lysine residues activates liver alcohol dehydrogenase in the oxidation of primary alcohols, but decreases the activity of the enzyme towards secondary alcohols. The modification also desensitizes the dehydrogenase to substrate inhibition at high alcohol concentrations. Steady-state kinetic studies of methylated liver alcohol dehydrogenase over a wide range of alcohol concentrations suggest that alcohol oxidation proceeds via a random addition of coenzyme and substrate with a pathway for the formation of the productive enzyme-NADH-alcohol complex. To facilitate the analyses of the effects of methylation on liver alcohol dehydrogenase and factors affecting them, new operational kinetic parameters to describe the results at high substrate concentration were introduced. The changes in the dehydrogenase activity on alkylation were found to be associated with changes in the maximum velocities that are affected by the hydrophobicity of alkyl groups introduced at lysine residues. The desensitization of alkylated liver alcohol dehydrogenase to substrate inhibition is identified with a decrease in inhibitory Michaelis constants for alcohols and this is favoured by the steric effects of substituents at the lysine residues.

Acetaldehyde↗
PubMed1976

Kinetic effect of some aliphatic amines on yeast alcohol dehydrogenase.

Initial rate studies of ethanol oxidation catalyzed by yeast alcohol dehydrogenase (EC 1.1.1.1) were carried out in the presence of varying concentrations of aliphatic amines over the pH range from 8.0 to 10.5. Aliphatic amines either activate or inhibit the enzyme depending on whether the pH is greater or less than 9.5 suggesting that the protonated amines activate and the nonprotonated amines inhibit the enzyme. Aliphatic amines activate yeast alcohol dehydrogenase by decreasing Kb while they inhibit the enzyme by increasing both Ka and Kia. When both protonated and nonprotonated amines are present in solution, either overall activation or inhibition will be observed depending on the relative concentration of the two amine species.

Alcohol Oxidoreductases↗
PubMed1975

A kinetic study of dihydrolipoyl transacetylase from bovine kidney.

The mammalian pyruvate dehydrogenase complex contains a core, consisting of dihydrolipoyl transacetylase, to which pyruvate dehydrogenase and dihydrolipoyl dehydrogenase are joined. This report describes studies on the kinetic mechanism of the transacetylase-catalyzed reaction between [1-14C]acetyl-CoA and dihydrolipoamide. This reaction appears to be a model of the physiological reaction, in which the acetyl group is transferred from the S-acetyldihydrolipoyl moiety, bound covalently to the transacetylase, to CoA. The model reaction is not affected by pyruvate dehydrogenase or dihydrolipoyl dehydrogenase, their substrates and products, or by removal of the covalently bound lipoyl moiety. These findings, together with the results of initial velocity, product inhibition, and dead-end inhibition studies, indicate that the model reaction and, apparently, the physiological reaction as well, proceeds via the Random Bi Bi (rapid equilibrium) mechanism. It appears that at the catalytic center of the transacetylase there are two adjacent sites, one that binds CoA and acetyl-CoA and another that binds dihydrolipoamide and S-acetyldihydrolipoamide (or the corresponding forms of the covalently bound lipoyl moiety.

Acetates↗
PubMed1975

Characterization of malate dehydrogenase isozymes in wheat germ.

Malate dehydrogenase of wheat germ exists in multiple molecular forms (isozymes). Comparisons of some physical properties such as Stoke's radii, sedimentation constants, electrophoretic mobilities on polyacrylamide gel, chromatographic behaviors on DEAE-cellulose, stabilities to heat and iodacetamide inactivation, as well as kinetic parameters were described. When all these properties are considered together, at least five isozymes were found to associate with cytoplasm, mitochondria, glyoxysomes and proplastids of wheat germ. Wheat germ malate dehydrogenases are specific for the reduction of oxaloacetate and its monoesters. At least one carboxylic group of oxaloacetate must be free, in order to exhibit substrate activity, and maximum binding of oxaloacetate is achieved when both carboxylic groups are free. Soluble malate dehydrogenase and organelle-associated malate dehydrogenase can be differentiated readily in that the former can not utilize 4-ethyl oxaloaceode of ATP inhibition.

Chloroplasts↗
PubMed1975

Serologic study of toxoplasmosis in Taiwan.

Toxoplasma gondii antibody titers as determined by either the indirect hemagglutination test or the methylene blue dye test were determined for a group of aborigines and for Chinese as well as for swine, cats, rats, dogs and one bovine, all resident on the island of Taiwan. None of the 194 aborigines and only 3 (1.97%) of the 152 Chinese were found to be positive. Of 433 swine tested 132 (30.5%) were positive. Thirteen (27.7%) of 47 domestic pet cats were positive while none of 11 feral cats were positive. None of the 29 rats, 3 dogs or the one bovine were positive. Possible reasons for the lack of infection in Chinese is discussed.

Animals↗
PubMedDate not supplied

Neurochemical correlates of alcohol preference in inbred strains of mice.

C57B1/6J, a specific inbred strain of mice with high alcohol preference and DBA/2J, a specific inbred strain with poor preference for alcohol were studied. Brain content of acetylcholine, uptake of 14C-Choline by whole brain homogenate were significantly higher in the C57B1/6J mice whereas brain acetylcholinesterase was higher in the DBA/2J mice. No significant difference was found for the level of brain serotonin, uptake of 3H-norepinephrine or 3H-dopamine. Treatment with a specific inhibitor of choline transferase, 4-(1-napthylvinyl) pyridine salt (10 mg/kg, twice daily) shifted the selection of alcohol to water in the C57B1/6J mice. These findings suggest a direct involvement of central cholinergic mechanism in alcohol preference.

Acetylcholine↗