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Biomedical subjects

K Prema

Publications and source records attributed to K Prema.

52 records · Page 3Linked to original sources
PubMed1979

Lactation and fertility.

During the last decade there have been many reports indicating a decline in breast feeding practices in the urban areas of developing countries. This decline might have adverse effects on maternal and child health. A study of 1079 urban hospital attending women was undertaken to evaluate their breast feeding practices. Prolonged (mean duration of lactation 19.8 months) and successful lactation (failure of lactation occurred in only 3.5%) was common among this group. But a trend toward shorter duration of breast feeding was found among educationally and economically better off segment. There was very good correlation between mean duration of lactation, lactational amenorrhea, and interpregnancy interval. Therefore, it is possible that decrease in duration of lactation might result in shorter interpregnancy interval. The duration of lactation appeared to be "fixed" for each individual irrespective of age and parity. This in turn resulted in "fixed" duration of lactational amenorrhea and interpregnancy interval under conditions of unhindered lactation and uncontrolled fertility. Conception during lactational amenorrhea was low (7.7%) but once periods were reestablished lactation offered very little protection against conception.

Adolescent↗
PubMed1974

Involvement of the superoxide anion in sulphoxidation.

Sulphoxidation of compounds capable of undergoing biological sulphoxidation has been demonstrated in a model system (NADH-phenazine methosulphate-O(2)), known to generate superoxide anions (O(2) (-)). Addition of superoxide dismutase to this system results in complete inhibition, suggesting the involvement of O(2) (-) in sulphoxidation.

Animals↗
PubMed1974

An oxygenase from guinea-pig liver that catalyses sulphoxidation.

A mono-oxygenase catalysing the conversion of 2-ethyl-4-thioisonicotinamide (ethionamide) into its sulphoxide was purified from guinea-pig liver homogenates. The enzyme required stoicheiometric amounts of oxygen and NADPH for the sulphoxidation reaction. The purified protein is homogeneous by electrophoretic, antigenic and chromatographic criteria. The enzyme has mol.wt. 85000 and it contains 1g-atom of iron and 1mol of FAD per mol, but not cytochrome P-450. The enzyme shows maximal activity at pH7.4 in a number of different buffer systems and the K(m) values calculated for the substrate and NADPH are 6.5x10(-5)m and 2.8x10(-5)m respectively. The activation energy of the reaction was calculated to be 36kJ/mol. Under optimal conditions, the molecular activity of the enzyme (mol of substrate oxidized/min per mol of enzyme) is calculated to be 2.1. The oxygenase belongs to the class of general drug-metabolizing enzymes and it may act on different compounds which can undergo sulphoxidation. The mechanism of sulphoxidation was shown to be mediated by superoxide anions.

Animals↗
PubMed1970

Sulphadimidine acetylation test for classification of patients as slow or rapid inactivators of isoniazid.

Sulphadimidine acetylation studies were undertaken in 103 patients, 52 of whom had been classified as slow and 51 as rapid inactivators of isoniazid by a standard microbiological assay method. Each patient received sulphadimidine by mouth in a dose of 44 mg./kg. body weight, and free and total sulphadimidine were estimated in blood and urine collected at six hours. The findings suggest that patients may be classified as slow inactivators of isoniazid if the proportion of acetylated sulphadimidine (total minus free) is (a) less than 25% in blood or (b) less than 70% in urine. The sulphadimidine test is easy to perform and the result is available the same day; urine specimens for the test can be stored at room temperature for over a week without any loss of drug.

Acetates↗