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Biomedical subjects

S R Guha

Publications and source records attributed to S R Guha.

At least 19 recordsLinked to original sources
PubMed1989

A colorimetric method for assay of serotonin deamination by monoamine oxidase.

The present method involves conversion of the aldehyde produced, as a result of serotonin deamination by monoamine oxidase, to its 2:4 dinitrophenyl hydrazone derivative which gives a stable, bright yellow colour in alkaline solution and can be measured colorimetrically. The derivative is however unstable in the acidic medium and has to be extracted into an organic solvent immediately. The details of the method and its standardization are discussed.

Animals↗
PubMed1985

In vitro pigment formation from tryptamine. Role of indole-3-acetaldehyde.

The metabolic significance of indole-3-acetaldehyde in the process of in vitro pigment formation from tryptamine in the presence of guinea-pig liver mitochondria was investigated. Among the four type selective MAO inhibitors used, pargyline and deprenyl appear to be more effective in inhibiting pigment formation from tryptamine than serotonin, while in the presence of clorgyline and Lilly 51641, pigment formation from serotonin was preferentially inhibited. Reducing agents like ascorbic acid, cysteine and glutathione were found to block pigment formation significantly. Also, a reduction of pigment formation was noted in the presence of NADH and ethanol but not in the presence of NAD. It was observed that the amount of indole-3-acetaldehyde produced enzymatically from tryptamine under the present experimental conditions is not sufficient to account for the total amount of pigment formed in the standard incubation mixture and the generation of nascent aldehyde has greater contribution in pigment formation than that supplemented to the system exogenously. It appears that indole-3-acetaldehyde, tryptamine and MAO are associated with the process of pigment formation.

Animals↗
PubMed1982

GABA dehydrogenase activity in rat brain.

The crude mitochondrial fraction of rat brain contains an active dehydrogenase involved in the direct oxidation of gamma-aminobutyric acid. INT (p-iodonitrotetrazolium violet) can serve as an efficient acceptor of electrons in this dehydrogenase reaction. During this oxidation of GABA, ammonia is not produced. In vitro the dehydrogenase activity is inhibited by certain MAO inhibitors. The effects of various inhibitors of GABA-T and GAD were also investigated. The dehydrogenase activity was found to be susceptible to various anti-convulsants and inhibitors of electron transport. The co-factors which may be involved in the transfer of electrons during GABA oxidation in the presence of INT are also discussed.

Animals↗
PubMed1982

Biogenic aldehyde metabolism in rat brain: subcellular distribution of aldose reductase and valproate-sensitive aldehyde reductase.

Reductase activity towards two aldose substrates has been examined in subcellular fractions prepared from rat brain. The reduction of glucuronate, which is sensitive to inhibition by the anticonvulsant drug sodium valproate, corresponds to the major high-Km aldehyde reductase in brain. Xylose reduction that is insensitive to valproate inhibition has characteristics consistent with the activity of aldose reductase (EC 1.1.1.21). Both enzymes are predominantly localized in the cytosolic fraction. The significance of the location of these two reductases is discussed in relation to the compartmentation of catecholamine metabolism in brain.

Alcohol Oxidoreductases↗