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Biomedical subjects

S Mehrotra

Publications and source records attributed to S Mehrotra.

18 recordsLinked to original sources
PubMed1992

Peptidolytic monoclonal antibody elicited by a neuropeptide.

We report evidence that a monoclonal antibody raised by immunization with a vasoactive intestinal peptide (VIP)-carrier protein conjugate selectively hydrolyzes VIP and a fluorescence quenched decapeptide (FQ14-22D), representing the region of VIP most susceptible to autoantibody-mediated cleavage (residues 14-22). A high affinity of the antibody for VIP and a lower affinity for FQ14-22D were revealed by kinetic studies and further substantiated by potent inhibition of FQ14-22D cleaving activity by full-length VIP. Sequencing of FQ14-22D hydrolysis products indicated selective cleavage at one peptide bond. These observations suggest that antibodies induced against naturally occurring polypeptide antigens can express peptidolytic activity targeted for specific sequences in the recognition epitope.

Amino Acid Sequence↗
PubMed1992

Interrelation of active oxygen species, membrane damage and altered calcium functions.

Incubation of freshly isolated rat liver mitochondria in the presence of oxygen free radical generating hypoxanthine-xanthine oxidase system led to swelling of mitochondria as measured by the change in optical density, which was reversed by the addition of superoxide dismutase. O2- in the presence of CaCl2 enhanced the peroxidative decomposition of mitochondrial membrane lipids along with swelling of the organelle. Free radical generation led to enhancement of monoamine oxidase activity while glutathione peroxidase and cytochrome c oxidase were inhibited. Tert-butyl hydroperoxide (t-BHP) caused mitochondrial swelling through oxidative stress. Incorporation of ruthenium red, which is a Ca2+ transport blocker, during assay abolished peroxidative membrane damage and swelling. Dithiothreitol (DTT) accorded protection against t-BHP induced mitochondrial swelling. The above in vitro data suggest a possible interrelationship of active oxygen species, membrane damage and calcium dynamics.

Animals↗
PubMed1991

Mitochondrial damage by active oxygen species in vitro.

Under in vitro conditions involving formation of active oxygen species, rat liver mitochondria were found to undergo swelling, peroxidative decomposition of lipids, and distinct disorganization of ultrastructure. Supplementation with free radical scavengers such as superoxide dismutase (SOD), methionine, histidine, and tryptophan accorded considerable protection to the organelle. A possible correlation between oxygen radicals, membrane integrity, and calcium functions is indicated.

Animals↗
PubMed1991

Importance of oxygen functions in the biological hydroxylation of flavonoids by Absidia blackesleeana.

1. The synthesis and microbiological transformation of 2-phenyl-1-tetralone (compound 3, 1-deoxyisoflavanone), 3-phenyl-1-tetralone (compound 4, 1-deoxyflavanone), 2-phenylchroman (compound 7, 4-deoxyflavanone), 3-phenylchroman (compound 8, 4-deoxyisoflavanone) and 1,2-dihydro-3-phenylnaphthalene (compound 10, 1,4-dideoxy-dehydroflavanone) by Absidia blackesleeana are described. 2. Compounds 3, 4, 7 and 8 were hydroxylated at the 4'-position while compound 10 was not utilized as a substrate. The two phenylchroman analogues 7 and 8 gave approximately the same yield (22% and 26%, respectively) of the 4'-hydroxylation products, while the phenyltetralone analogues 3 and 4 showed significant differences in 4'-hydroxylation (2% and 47%, respectively).

Flavonoids↗
PubMed1989

Alkaptonuria.

A case of alkaptonuria with its various sequelae in the form of ochronosis, ochronotic arthropathy, spondylitis and prostatic calculi is reported. The case is of interest as it presented with hepatocellular failure and hepatitis B surface antigenaemia.

Alkaptonuria↗
PubMed1985

Role of neurotransmitters in endosulfan-induced aggressive behaviour in normal and lesioned rats.

Normal and lesioned rats exposed to 3 mg/kg i.p. endosulfan for 10 subsequent days showed elevated foot-shock fighting behaviour in septal and nigral brain-lesioned animals. Increased ipsilateral circling was noticed in unilateral-nigral lesioned rats. A marked decrease in locomotor activity and no seizure pattern were recorded in rats treated with chlorpromazine (CPz). Electroencephalographic recording on the tenth day of endosulfan exposure showed high-voltage slow activity (HVSA) with occasional spindles and 5-6 Hz amplitude of 200 microV. In the treated rats an increase in the concentration of dopamine (DA) and a decrease in serotonin (5-HT) were recorded in amygdaloid, septal and nigral brain-lesioned rats.

Aggression↗
PubMedDate not supplied

Organochlorine pesticide residues in different Indian cereals, pulses, spices, vegetables, fruits, milk, butter, Deshi ghee, and edible oils.

A total of 244 samples of cereals (wheat flour, rice, and maize), pulses (arhar, moong, gram, lentil, and black gram), spices (turmeric, chili, coriander, and black pepper), vegetables (potato, onion, spinach, cabbage, brinjal, and tomato), fruits (mango, guava, apple, and grape), milk, butter, Deshi ghee, and edible oils (vegetable, mustard, groundnut, and sesame) collected from different cities of Northern Province (Utter Pradesh) were analyzed by gas liquid chromatography for the presence of organochlorine pesticide residues. Residues of hexachlorocyclohexane (HCH) and 2,2-bis(p-chlorophenyl)-1,1,1-trichloroethane (DDT) were detected in about 85% of the total samples of cereals, spices, milk, butter, Deshi ghee, and edible oils analyzed in the present study. However, the residue levels were either very small (less than 0.06 ppm) or not detected at all in pulses, vegetables, and fruits as compared with very high concentrations in wheat flour (4.42 and 0.12 ppm), butter (1.19 and 4.85 ppm), mustard oil (1.26 and 2.42 ppm), Deshi ghee (1.10 and 3.84 ppm), vegetable oil (1.02 and 0.59 ppm), groundnut oil (0.51 and 1.49 ppm), and chili (0.48 and 1.92 ppm). The levels of HCH and DDT residues detected in rice, maize, turmeric, corlander, black pepper, and all the vegetables and fruits were also lower than those found in wheat flour, oil, and fat samples analyzed in the present study. These findings suggest that a restricted and controlled use of such persistent pesticides may be useful for decreasing their contamination levels in different food items.

Animals↗