PubMed Health⌕ Search

Biomedical subjects

R Raghunathan

Publications and source records attributed to R Raghunathan.

29 records · Page 2Linked to original sources
PubMed1980

Effect of mercury compounds on cholineacetyl transferase.

Methylmercury poisoning exhibit prominent signs and symptoms of the central nervous system. In an attempt to study the mechanism of toxicity, mercuric chloride (HgCl2) and methyl mercury chloride (CH3HgCl) were given orally by gavage and through drinking water to male albino rats. Rats were sacrificed at appropriate time and brain and diaphragm were analyzed for cholineacetyltransferase (ChAT) activity, and also examined histopathologically. Both HgCl2 and CH3HgCl given orally by gavage significantly inhibited ChAT activity which was dose related. CH3HgCl produced greater inhibition than HgCl2. CH3HgCl through drinking water also significantly inhibited brain ChAT, however rats did not drink water containing HgCl2. Both HgCl2 and CH3HgCl also inhibited ChAT when incubated in vitro with rat brain homogenates. Histopathological studies revealed neural degeneration and necrosis in the cerebrum of rats treated with these mercurials. These results indicate the possible involvement of cholinergic system during mercury intoxication.

Animals↗
PubMed1978

Induction of mitochondrial phosphoenolpyruvate carboxykinase in cultured human fibroblasts.

Mitochondria of cultured normal human fibroblast cells were found to contain the enzyme phosphoenolpyruvate carboxykinase. The activity of this enzyme in these cells is increased 2- to 3-fold by addition of 5 . 10(-4) M dibutyryl cyclic AMP, or 1.5- to 2-fold by the addition of dexamethasone (2 . 10(-7) M) or hydrocortisone (1.38 . 10(-6) M). These increases in enzyme activity were inhibited cycloheximide and actinomycin D, suggesting they are dependent upon de novo protein synthesis. Cultured human fibroblasts may thus provide a useful system for studying the regulation of mitochondrial phosphoenolpyruvate carboxykinase.

Bucladesine↗
PubMed1977

Pyruvate carboxylase and phosphoenopyruvate carboxykinase in cultured human fibroblasts.

The activities of pyruvate carboxylase and phosphoenolpyruvate carboxykinase were measured in cultural human fibroblasts. Considerable variation was observed in strains derived from different individuals. The activities of both enzymes throughout the culture cycle were measured in two strains. In these strains the specific activities of the enzymes increased during log phase and remained constant during the stationary phase. However, one cell strain exhibited a high activity of pyruvate carboxylase which remained unchanged throughout the culture cycle, suggesting that this enzyme may be regulated differently in different strains of cultured human cells. Familial studies suggest that the observed variations in pyruvate carboxylase activity may be due to a genetic polymorphism.

Avidin↗
PubMed1976

Structure-activity studies on mammalian tissue lytic enzymes: chemical characterization and substrate specificity of rat kidney nuclear lysozyme.

Studies on the structure and substrate specificity of purified rat kidney nuclear (RKN) lysozyme are reported. The carboxyl and amino terminal residues of RKN-lysozyme were found to be leucine and alanine respectively. The amino acid composition indicated similarities and differences as compared with that of hen egg white (HEW) lysozyme. There were alterations in the nine amino acid residues, Lys, His, Arg, Asp, Glu, Pro, 1/2 Cys, Tyr and Trp. The other nine residues were present in identical proportions to those of HEW-lysozyme. The decrease in the arginine and aspartic acid residues was found to be compensated by the increase in the number of lysine, histidine and glutamic acid residues. The overall ratio of the acidic to basic amino acids has thus been conserved in the mammalian enzyme. In addition, RKN-lysozyme contained decreased numbers of Trp, Tyr and 1/2 Cys, and increased numbers of proline residues as found in HEW-lysozyme. RKN-lysozyme did not cross react with heterologous antibodies produced against HEW-lysozyme, and vice versa. RKN-lysozyme showed distinct specificity towards the lysis of M. luteus. Against this substrate, it was three times more efficient than HEW-lysozyme. It also cleaved E. coli B, but its efficiency was half as much as with M. luteus. However, it cleaved P. septica and B. subtilis at a rate similar to HEW-lysozyme under identical conditions.

Amino Acid Sequence↗