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Biomedical subjects

J C Shih

Publications and source records attributed to J C Shih.

At least 181 records · Page 10Linked to original sources
PubMed1978

Radial diffusion assay of NAD- and NADP-dependent oxidoreductases.

With a radial diffusion assay we measured the activity of six NAD- and NADP-dependent oxidoreductases: alcohol, glucose-6-phosphate, hydroxysteroid, lactate and malate dehydrogenases, and glutathione reductase. The enzyme was allowed to diffuse for 24h in an agarose gel in which the substrate was incorporated, then reacted the pyridine nucleotide coenzyme. The size of an enzyme diffusion zone could be made visible by the change of the fluorescence of the coenzyme against the background when the coenzyme was either oxidized or reduced. The procedure for each enzyme is reported. The results indicate that this new technique may be applicable to all NAD- and NADP-dependent enzymes. Because of its simplicity and potentiality for screening many samples, we think this method has applications in the clinical laboratory and in nutrition studies.

Alcohol Oxidoreductases↗
PubMed1977

Oxidative deterioration of the muscle proteins during nutritional muscular dystrophy in chicks.

Nutritional muscular dystrophy in the chick results from the simultaneous deficiency of vitamin E and cystine. Being a biological antioxidant, vitamin E might be functional in maintaining a proper redox state of the sulfur-containing amino acid in the proteins. The analyses of protein-bound sulfhydryls and disulfides at onset of muscular dystrophy in young chicks were carried out. The ratio of disulfide to sulfhydryls increased two- to three-fold in dystrophic muscle as compared to that in the control muscle proteins. Dystrophic and normal muscle proteins also were subjected to SDS-gel electrophoresis. Proteins of low molecular weight, supposedly derived from proteolysis, were present in the gels of the dystrophic muscle and absent in those of normal muscle extracts. As a result of these studies, a chemical model has been proposed to explain the oxidative deterioration of proteins in nutritional muscular dystrophy due to vitamin E deficiency.

Amino Acids, Sulfur↗
PubMed1977

Changes of lipoamide dehydrogenase and mitochondrial structure in selenium-deficient chicks.

A selenium deficiency in chicks produces degeneration and fibrosis of the pancreas. An investigation was undertaken to determine whether or not the activity of lipoic acid is impaired in the pancreas of selenium-deficient chicks. Enzymatic analyses of selenium-deficient chick tissues showed a reduction in lipoamide dehydrogenase both in pancreas and liver at a very early stage of growth. Using both direct measurements and sucrose-gradient cellular fractionation, it was found that the lipoamide dehydrogenase activity of the supernatant increased, and that of the mitochondria decreased in selenium-deficient as compared to normal chick livers. These results indicate an increased fragility of the mitochondrial membranes in selenium-deficient chicks.

Animals↗
PubMed1977

The specific interaction between LSD and serotonin-binding protein.

In this report, we describe the chemical interaction between lysergic acid (LSD) and serotonin-binding protein (SBP) by a three-dimensional spectroscopic technique. This instrument records simultaneously the activation and fluorescence spectra, and plots fluorescence intensity level by a series of isointensity contours. Free LSD exhibits maximum fluorescence at 435 nm with excitation maximum at 330 nm. While SBP-bound LSD shifted its fluoresence and excitation maximum to 465 nm and 375 nm respectively. These results suggest that the drug-protein interaction caused an extensive delocalization of the molecular orbital electrons and thereby lengthen the electronic conjugation of the drug molecule. Such shift was not observed when LSD was incubated with bovine serum albumin under the same condition. This technique is sensitive and requires a small volume of samples. It permits us to determine both free and bound drug in the same sample and provides us specific information about the drug and protein interaction.

Animals↗
PubMed1976

Determination of antitrypsin activity on agar plates: relationship between antitrypsin and biological value of soybean for trout.

A new method is described for determination of antitrypsin activity based on inhibition of trypsin solubilization of calcium caseinate in agar plates. The method was applied to analyze soybeans after graded heat treatments for their antitrypsin content. Biological determination of protein and energy values of the soybean samples showed direct correlation of these values with the destruction of antitrypsin as measured by the new method, using rainbow trout.

Animals↗
PubMed1975

Characterization of the growth of Pseudomonas putida LP on lipoate and its analogues: transport, oxidation, sulphur source, and enzyme induction.

Pseudomonas putida LP, which grows on lipoate, NH4NO3 and mineral salts, converts most of the organic substrate to bisnor-lipoate (1,2-dithiolane-3-propanoic acid) and acetyl-CoA. D-, L-, or DL-lipoate serve equally well as carbon and sulphur sources. There was no growth on or bacterial oxidation of the chemically synthesized bisnor- or tetranor-(1,2-dithiolane-3-carboxylic acid) chain-shortened analogues, but these, as well as lipoate, could supply the sulphur needed for growth when acetate was provided as the sole source of carbon. The uptake of lipoate by the bacterium is very slow and non-inducible, while the uptake of acetate is faster than octanoate. The oxidation of octanoate is more rapid and extensive than that of lipoate. Levels of acyl-CoA synthetase are not affected by the source of carbon, but activities of isocitrate lyase and malate synthase are higher when the cells are grown in acetate, octanoate or lipoate and lower when glucose is the carbon source. The glyoxylate cycle is induced to facilitate utilization of acetyl-CoA derived from lipoate, which is also degraded to water-soluble catabolites that yield the much smaller amount of sulphur required for growth.

Acetates↗
PubMed1972

Isolation, identification, and characterization of a lipoate-degrading pseudomonad and of a lipoate catabolite.

A strain of bacteria that can degrade lipoic acid was isolated from soil. The bacterium, adapted to use 0.4% dl-lipoate as the sole organic substrate to supply carbon, sulfur, and energy, was identified morphologically and physiologically as a strain of Pseudomonas putida. Degradation of 1,6-(14)C-lipoic acid, synthesized from 1,6-(14)C-adipic acid, was evidenced by: (i) loss of approximately 50% of the total radioactivity from the medium after bacterial growth; (ii) appearance of (14)C-degradation products upon paper and thin-layer chromatography of the culture medium; and (iii) oxygraphically measured utilization of O(2) by cells in the presence of lipoate or other oxidizable substrates. Analyses of the benzene extract of culture medium by infrared, nuclear magnetic resonance, and mass spectrometry, and by gas-liquid chromatography after desulfuration, have characterized bisnorlipoic acid, or 4,6-dithiohexanoic acid, as the major catabolite present in the medium. beta-Oxidation of the side chain is thus proven to be a pathway employed by the pseudomonad to degrade lipoic acid.

Acetates↗