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Biomedical subjects

M S Akhtar

Publications and source records attributed to M S Akhtar.

47 records · Page 3Linked to original sources
PubMed1979

Effect of methylene blue and thiol oxidants on pancreatic islet GSH/GSSG ratios and tolbutamide mediated insulin release in vitro.

Methylene blue (an oxidant of NADPH), diamide (an oxidant of glutathion-SH [GSH]) and tertbutyl hydroperoxide (a substrate of glutathione peroxidase) significantly decreased the GSH content of pancreatic rat islets and decreased their GSH/GSSG ratio. They also significantly depressed the single peak insulin response to tolbutamide by the isolated perfused pancreas as well as its synergistic action with glucose in isolated pancreatic islets. These results suggest that the effect of tolbutamide alone and its synergistic action with glucose could depend on the islet NADPH and GSH. In addition it appears that augmentation of tolbutamide action by glucose in insulin release is mediated by the provision of additional NADPH and GSH through glucose metabolism.

Animals↗
PubMed1979

Effect of leucine on the pyridine nucleotide contents of islets and on the insulin released--interactions in vitro with methylene blue, thiol oxidants, and p-chloromercuribenzoate.

In the presence of glucose (2 mg/ml), leucine (10 mM) noticeably increased islets' NADPH contents as well as the NADPH:NADP ratio; the changes occurred as soon as 1 min after its addition. NADH concentrations were also increased by leucine. The NADPH:NADP ratio as well as insulin release stimulated by glucose plus leucine were markedly decreased by methylene blue. The thiol oxidants diamide and tert-butyl hydroperoxide also inhibited insulin secretion in response to glucose plus leucine. Employing the perfused pancreas technique, the insulin-releasing action of p-chloromercuribenzoate was further enhanced by leucine. The combined effects were inhibited by tert-butyl hydroperoxide, however. Our data suggest that the insulin-releasing action of leucine depends on the islets' NADPH and reduced glutathione (GSH); in addition, leucine may contribute to insulin secretion by increasing the islet NADPH:NADP ratio and the NADH:NAD ratio. From the data, we assume that the observed increase of NADPH may lead via GSH to an increase in the number of such thiol groups in the beta-cell membrane, which are believed to be related to stimulation of insulin release and, thus, to increase the sensitivity of the beta-cell to stimulation by glucose and/or leucine.

Animals↗
PubMed1977

6-Phosphogluconate/glucose-6-phosphate ratio in rat pancreatic islets during inhibition of insulin release by exogenous insulin.

Inhibition of glucose-stimulated insulin release by exogenous insulin has been demonstrated in pancreatic islets to be associated with a decrease of the NADPH/NADP ratio and the pentose-phosphate cycle activity. Batches of five islets were incubated for 15 and 90 minutes in 1 ml. of KRB buffer with 2 per cent albumin containing 3 mg./ml. glucose and 0, 200, 400, or 800 microU./ml. of rat insulin, and the glucose-6-phosphate (G6P) and 6-phosphogluconate (6PG) contents were determined by enzymatic cycling. In response to a rise in the concentration of insulin, the 6PG/G6P ratio decreased. A close relationship was observed between this decrease of 6PG/G6P ratio and the net insulin release, the absolute rate of glucose oxidation via the pentose phosphate cycle, and the NADPH/NADP ratios measured under similar conditions. The results suggest that exogenous insulin, directly or indirectly, regulates the pentose cycle activity in the pancreatic islets at the G6P dehydrogenase step.

Animals↗
PubMedDate not supplied

Metabolic effects of alcoholism and its relationship with alcoholic liver disease.

BACKGROUND: Chronic and excessive ethanol consumption is associated with cellular proliferation, fibrosis, cirrhosis and cancer of liver. It was planned to study the effect of alcohol on different biochemical parameters as distribution of these parameters may lead to several complications in gastrointestinal tract, liver, kidney, brain etc. METHODS: 50 alcoholic males and 20 normal subject (with no history of alcohol) with an age ranges 30-45 years were included in the study. Biochemical parameters related to liver were estimated by standard kit. Besides, ions and electrolytes were also determined by standard kit and flame photometry. RESULTS: It was observed that level of alkaline phosphatase, alanine transferase, protein and globulin were significantly increased as compared to normal subjects. Besides, ions like calcium and phosphate were significantly decreased. On the other hand the level of potassium and magnesium was significantly decreased as compared to normal subjects. Electrophoresis shows a protein of 100 Kda is present in the patients sample as compared to control subjects. CONCLUSION: It is therefore concluded that abnormal biochemical function of liver in alcoholism can lead to several complications, hence further research is needed to reach a definite conclusion.

Adult↗