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Biomedical subjects

R S Bhatnagar

Publications and source records attributed to R S Bhatnagar.

At least 55 records · Page 3Linked to original sources
PubMed1978

Macromolecular synthesis in organ cultures of neonatal rat lung.

Organ cultures of newborn rat lungs synthesize and accumulate DNA, RNA, collagen and noncollagenous proteins almost at a linear rate for at least 5 days. During this period the synthesis of collagen consistently exceeds the synthesis of noncollagenous proteins in a pattern similar to neonatal lung growth in vivo. Although some morphological characteristics of lung architecture are distorted after culture, fundamental structural similarities to lungs growing in intact animals are retained. When these cultures are maintained in atmospheres rich in oxygen, increased collagen synthesis is observed, a response similar to that of lungs in intact animals exposed to high oxygen concentrations in vivo. Our studies suggest that lung organ cultures may be a suitable system for investigating the biochemical aspects of lung tissue-environmental interaction.

Animals↗
PubMed1977

Biochemical basis of skeletal defects induced by hydralazine: inhibiton of collagen synthesis and secretion in embryonic chicken cartilage in vitro.

Hydralazine (1-hydrazinophthalazine) produces skeletal defects resembling those observed in experimentally induced manganese deficiencies. Since glycosylation of collagen, a step preceding its secretion, requires Mn2+, the effect of hydralazine on collagen secretion and the formation hydroxylysine glycosides was examined in explants of embryonic chicken long-bone rudiments. Auto-radiographic studies showed that hydralazine blocked collagen secretion. Secretion was restored by Fe2+ alone or Fe2+ + Mn2+ but not by Mn2+ alone, suggesting that a Fe2+-requiring step was involved. Biochemical analyses showed that hydralazine inhibited the formation of hydroxylysine, a step requiring Fe2+, but it did not inhibit the formation of hydroxylysine-glocosides by Mn2+-requiring steps, although the reaction was inhibited in vitro. Hydralazine also failed to inhibit intracellular mucopolysaccharide synthesis which involves several Mn2+-requiring enzymes. These observations suggest that the deleterious effects of hydralazine on bones are caused by its inhibition of hydroxylation steps in collagen synthesis.

Abnormalities, Drug-Induced↗
PubMed1976

Inhibition of hydroxyproline synthesis by palladium ions.

Palladium ions, administered as PdSO4, markedly affect the incorporation of L-[3,4-3H2] proline into non-dialyzable fractions in 10-day chick embryo cartilage explants with a 55-65% reduction in the concentration range 0.06-0.6 mM. Under these conditions the synthesis of [3H]hydroxyproline was nearly completely inhibited. Experiments with prolyl hydroxylase (EC 1.14.11.2) indicated a strong irreversible inhibition of the enzyme with a competition between Fe2+ and Pd2+. The Ki for the inhibition was 0.02 mM. Pd2+-treated enzyme remained inactive after extensive dialysis. These studies suggest that Pd2+ may inhibit collagen synthesis by replacing Fe2+ in the active site of prolyl hydroxylase and forming strong complexes with the enzyme. These studies also point to a potential mechanism of Pd2+ toxicity.

Animals↗