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Biomedical subjects

C Mohan

Publications and source records attributed to C Mohan.

At least 91 records · Page 5Linked to original sources
PubMed1986

Intracellular site of insulin action: mitochondrial Krebs cycle.

Effect of insulin on the oxidation of carbons-1,4 and -2,3 of succinate and their incorporation into protein were studied in isolated rat hepatocytes and diaphragm muscle pieces. Oxidation of carbons-2,3 of succinate and their incorporation into hepatocyte protein were stimulated significantly by insulin. Insulin had only a trivial effect on 14CO2 formation from the carboxyl carbons of succinate. These data suggest that insulin affects only those carbons of succinate that are metabolized in the intramitochondrial Krebs cycle.

Animals↗
PubMed1986

Nutritional parameters that alter hepatic drug metabolism, conjugation, and toxicity.

A major concern of contemporary medicine is the adverse effects resulting from the use of prescribed and over-the-counter pharmacologic agents. In many cases more than one drug is taken at the same time, which increases the risk of overloading the detoxification mechanisms. If the individual has poor nutritional status, the system becomes even more inefficient. The liver contains the most important of these detoxification systems: the cytochrome P-450-dependent mixed function oxidase (MFO) and several conjugation enzymes, e.g., sulfotransferase, glucuronyl transferase, and glutathione transferase, which convert lipophilic compounds to more water-soluble products to enhance their excretion. The balance of these reactions determines the rate of metabolism and clearance of xenobiotic agents, and regulates in part the degree of intracellular damage. Nutritional factors, including proteins, carbohydrates, fats, vitamins, and minerals, affect the efficiency of these reactions. Changes in intracellular metabolism can alter not only the enzyme levels but also the availability of their cofactors, e.g., NADPH, UDPGA (uridine diphosphate glucuronic acid), PAPS (3'-phosphoadenosine-5'-phosphosulfate), and GSH. Diets restricted in calories, protein, or essential fatty acids, as well as those having low quality protein or high sugar content, can affect the component enzymes, cytochrome P-450 and the cytochrome P-450 reductase, and the MFO activity toward a variety of drugs. In addition, deficiencies of specific vitamins (riboflavin, ascorbic acid, and vitamins A and E) and minerals (iron, copper, zinc, and magnesium) affect the components and activities of the system in unique ways. Insight into the regulation of the hepatic detoxification mechanism can be gained by using nutrient variables to perturb the system.

Animals↗
PubMed1985

Anabolic regulation of gluconeogenesis by insulin in isolated rat hepatocytes.

The role of substrate availability in the regulation of gluconeogenesis in isolated rat hepatocytes was studied using [U-14C]alanine as a tracer in the presence of different concentrations of L-alanine in the incubation medium. At low alanine concentrations (0.5 mM) insulin decreased the 14C incorporation into the glucose pool and increased the incorporation of tracer carbons into the protein and lipid pools and into CO2. The net radioactivity lost from the glucose pool was only a small percentage of the total increase in the activity of the protein, lipid, CO2, or glycogen pools, supporting the notion that the effect of insulin in diminishing gluconeogenesis is secondary to its effects on pathways using pyruvate. At higher concentrations of alanine (2.5, 5.0, and 10.0 mM) in the incubation medium insulin increased the movement of alanine carbons into protein and glucose. This suggests that at higher substrate concentrations the ability of the liver to synthesize proteins is overwhelmed and the pyruvate carbons are forced into the gluconeogenesis pathway. These results were further confirmed by using [U-14C]lactate. The increases in observed specific activity of glucose following insulin administration would not be possible if insulin acted by affecting the activity of any enzyme directly involved in the formation or utilization of pyruvate, most of which have been proposed as sites of insulin action. Data presented show that insulin "inhibits" gluconeogenesis by affecting a change in substrate availability.

Alanine↗
PubMed1983

Inhibition of protein and lipid synthesis in muscle by 2,4-dinitrofluorobenzene, an inhibitor of creatine phosphokinase.

The incorporation of [3H]-valine into protein and [14C]-acetate into lipid was measured in rat diaphragm and hepatocytes after pretreatment of the tissue with 2,4-dinitrofluorobenzene (FDNB), an inhibitor of creatine phosphokinase (CPK) (EC2.7.3.2). The activity of CPK was also measured. Increasing concentrations of FDNB inhibited protein and lipid synthesis in muscle in parallel with the inhibition of CPK activity. In hepatocytes, which have little CPK activity, similar concentrations of FDNB had no effect on protein synthesis and little effect on lipid synthesis. The possible role of CPK and the creatine phosphate shuttle in muscle metabolism is discussed.

Animals↗
PubMed1981

Microbial fixation of nitrogen in the presence of lanthanum sulphate.

The effect of lanthanum sulphate on five Azotobacter strains (4A7, 10, 5A2, 5A1, and 3A3) isolated from Allahabad soil consists in a considerable increase in the nitrogen fixation, carbon consumption and in the amount of nitrogen fixed in mg per g of carbon consumed. The presence of 200 microM, 300 microM and 400 microM lanthanum sulphate in culture media increases the fixation of nitrogen by all the nitrogen fixers significantly.

Azotobacter↗
PubMed1981

Effect of sodium molybdate on microbial fixation of nitrogen.

The effect of 0, 100, 200, 300, 400, and 500 microM concentrations of sodium molybdate in the culture media of the five Azotobacter species isolated from Allahabad soil was studied. It was observed that the presence of molybdenum in the culture media of all the bacterial samples increased the fixation of nitrogen indicating that molybdenum is essential for increasing the efficiency of the nitrogen fixers for nitrogen fixation.

Azotobacter↗
PubMed1977

Prevalence of haemolytic streptococcal infection in rhesus monkeys.

Seventy-six monkeys arriving in 10 batches were investigated within a day or two of their arrival for beta-haemolytic streptococcal infections. 10.53 per cent of monkeys yielded group A beta haemolytic streptococcus. Majority of the isolates were T pattern I. With ASO test, 44.7 per cent monkeys had low titres while with A-DNase 'B' 'test, 64.5 per cent of the monkeys had low titres.

Animals↗