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Biomedical subjects

M L Gupta

Publications and source records attributed to M L Gupta.

At least 73 records · Page 4Linked to original sources
PubMed1980

Role of catecholamines in the central and peripheral actions of steroidal contraceptives.

The role of catecholamines in the mechanism of antiovulatory and other effects of steroidal contraceptive drugs has been studied in adult, healthy, nonpregnant female rats. It has been observed that oral administration of steroidal contraceptive pills (Lyndiol or Ovulen) daily for 14 days significantly reduced brain noradrenaline levels. This reduction in brain noradrenaline levels by these agents may be responsible for their antiovulatory and other central effects such as depression. The steroidal contraceptives were also found to significantly decrease the adrenaline content of adrenal glands without affecting the catecholamines content of heart and uterus. The significance of these findings in relation to cardiovascular and uterine complications of steroidal contraceptive drugs cannot be stated.

Adrenal Glands↗
PubMed1979

Gas-chromatographic analysis for valproic acid as phenacyl esters.

We describe a novel isothermal gas-chromatographic procedure for measuring valproic acid. Plasma, with cyclohexanecarboxylic acid added as internal standard, is selectively extracted with pentane to minimize the extraction of other acidic drugs. To convert carboxylic acids to their phenacyl esters, alpha-bromoacetophenone is added to the organic extract before evaporating the solvent. These esters are relatively less volatile than the acids themselves and the extracting solvent can be removed without any loss of valproic acid or internal standard. The phenacyl esters, when chromatographed on 3% OV-17, produce sharp, well-shaped peaks and show high response for the flame ionization detector. Valproic acid is well separated from the internal standard, from reagents and plasma constituents, and from some commonly prescribed drugs that we examined. When alpha-bromo-p-nitroacetophenone is sued as the derivatizing agent, the resulting nitrophenacyl esters can be analyzed with use of a nitrogen-specific detector.

Acetophenones↗
PubMed1979

Crypt cell population kinetics in mouse jejunum under continuous beta irradiation from tritiated water.

The behaviour of crypt cell population in mouse jejunum under continuous beta irradiation from tritiated water (HTO) has been studied. Adult mice were maintained on tritiated drinking water of the activity of 1.25 muCi/ml, after priming injection. The crypts were studied at 1, 5, 7, 15 and 30 days after the initiation of treatment. It is observed that there is a partial recovery in proliferative activity after the first day of the treatment. Again there is a decrease in the crypt cells on the 7th day, after which this population appears to achieve a near-steady-state level at about 8% below normal at the last interval studied. Crypt cell population and mitotic figures showed a simultaneous dip and recovery, while dead cells showed inverse relationship.

Animals↗
PubMed1977

Estimation of maprotiline in serum by gas-chromatography, with use of a nitrogen-specific detector.

We describe a gas-chromatographic procedure for estimating therapeutic concentrations of maprotiline, a new tetracyclic antidepressant, in serum by use of a nitrogen-specific detector. Desmethyldoxepin, a secondary amine similar in structure to maprotiline, is added as a mass internal standard to the specimen before extraction, to obviate the need for accurate measurements of volumes during extraction and analysis. Both maprotiline and the internal standard are converted to acetyl derivatives, to avoid the adsorption of secondary amines on the column. A highly selective liquid phase is used, which allows a very good separation of desmethyldoxepin, maprotiline, desmethylmaprotiline, and the interferences from serum and reagents.

Anthracenes↗
PubMed1976

Estimation of amitriptyline and its metabolites in serum and urine by GLC using nitrogen-specific detector.

1. A gas-chromatographic procedure for the estimation of amitriptyline and its metabolites in serum and urine using a nitrogen-specific detector is described. Specially cleaned glassware and purified solvents are used for the extraction of serum to further minimize extraneous peaks. Trimethylamine is added to serum before extraction to improve the recovery of drugs. Urine is refluxed at pH approximately 1 to hydrolyze the conjugates and to convert hydroxymetabolites to corresponding dehydro compounds. Serum is not hydrolyzed. 2. Two internal standards, one a tertiary amine similar in structure to amitriptyline and the other a secondary amine similar in structure to nortriptyline, are added to the specimen prior to extraction to obviate the need for accurate measurements of volumes during extraction and analysis. Urine and serum are washed with organic solvents at acidic pH to remove neutral and acidic impurities. Secondary bases are converted to their acetyl derivatives. 3. In the serum of a patient who is on amitriptyline therapy or who has ingested an overdose of amitriptyline, nortriptyline, a pharmacologically active metabolite is also measured. However, detection or estimation of hydroxymetabolites in serum is not clinically relevant. Hydroxylation index of an individual patient is determined by measuring the ratio of nortriptyline to its hydroxymetabolite in urine. 4. Amitriptyline and nortriptyline can be estimated in serum at a lower level of 10 and 20 ng/ml respectively. The procedure is linear over a wide range of amitriptyline and its metabolites. The use of an electronic integrator allows the estimation of different compounds with 100 fold difference in their concentration from the same chromatogram.

Amitriptyline↗