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Biomedical subjects

H N Bhagavan

Publications and source records attributed to H N Bhagavan.

At least 37 records · Page 2Linked to original sources
PubMed1986

Comparison of plasma alpha and gamma tocopherol levels following chronic oral administration of either all-rac-alpha-tocopheryl acetate or RRR-alpha-tocopheryl acetate in normal adult male subjects.

Vitamin E was administered orally (400 IU twice a day) to adult male humans for 28 days as either dl-alpha-tocopheryl acetate (all-rac-alpha-tocopheryl acetate) or d-alpha-tocopheryl acetate (RRR-alpha-tocopheryl acetate). Plasma alpha-tocopherol rose rapidly and fell at the same rate following cessation of supplementation with both forms of vitamin E. No significant differences in plasma alpha- or gamma-tocopherol levels were found between the two forms of vitamin E following their administration. The results confirm the currently accepted biopotencies of 1.0 IU/mg and 1.36 IU/mg, respectively for the two forms of vitamin E. Supplementation with either form of alpha-tocopheryl acetate resulted in depressing plasma gamma-tocopherol to less than 1/3 of initial levels; also the gamma/alpha ratio was depressed to less than 1/7 of the initial value. The study suggests that the gamma/alpha vitamin E ratio might also serve as a sensitive index of alpha-tocopherol ingestion.

Administration, Oral↗
PubMed1985

A double blind study of vitamin B6 in Down's syndrome infants. Part 1--Clinical and biochemical results.

Nineteen patients with Down's syndrome participated in a double blind study of the clinical effects of pharmacological doses of vitamin B6 administration, starting under 8 weeks of age and continuing until 3 years of age. Ten patients received the vitamin and nine the placebo. In Part 1 of this study, no statistically significant differences were found between the two groups in mental age, height, weight, cranial circumference or tongue protrusion. A study of side effects conducted on a larger open population found vitamin B6 to be relatively safe when administered over long periods of time with photosensitive blisters as the major complication.

Blister↗
PubMed1983

Drug--vitamin B6 interaction.

In conclusion, there are several drug types that can interfere with vitamin B6 metabolism. In most cases, the interaction involves a complex formation between the drug (or a derivative) and the reactive coenzyme PLP, resulting in a Schiff base. Such an interaction leads to an inactivation of PLP (and also of the drug). Other types of interaction involve (a) stimulation of vitamin B6-dependent pathways and (b) competition with PLP for the binding site on the enzyme. Examples of the above are the steroid hormones (oral contraceptives). In most instances, overt symptoms of vitamin B6 deficiency due to chronic ingestion of these drugs are observed, and neurological problems seem to be rather frequent. Because of the reactive nature of the coenzyme PLP and the ease with which it can interact with drugs, sub-clinical (marginal) vitamin B6 deficiency should be suspected in the absence of overt clinical signs. Once the vitamin B6 problem has been identified, the condition can usually be treated by judicious use of large doses of vitamin B6 without compromising the clinical efficacy of the drug.

Contraceptives, Oral↗
PubMed1979

A preliminary study of the effect of pyridoxine administration in a subgroup of hyperkinetic children: a double-blind crossover comparison with methylphenidate.

A small sample of six patients with the putative "hyperkinetic syndrome" participated in a research protocol comparing administration of pyridoxine, methylphenidate, and placeboes. The children had had low whole blood serotonin levels and a history of previous responsiveness to methylphenidate. The results of the double-blind clinical evaluation showed trends suggesting that both pyridoxine and methylphenidate were more effective than placebo in suppressing the symptoms of hyperkinesis. Pyridoxine elevated whole-blood serotonin levels, methylphenidate did not. Clinical and laboratory evidence indicated that the pyridoxine effects persisted after the 3-week period when the vitamin had been given in this experimental design.

Adolescent↗
PubMed1976

Effect of postweanling pyridoxine deficiency on growth and concentration of the coenzyme pyridoxal-5'-phosphate in heart, kidneys, lungs, and adrenals in rats.

Dietary pyridoxine deficiency induced in postweanling rats to led to severe growth retardation and growth failure, with a sharp increase in the mortality rate after about 8 weeks on the diet. The absolute weights of heart, lungs, kidneys, and adrenals were all lower in the deficient animals than those of the controls. However, when the weights were expressed in terms of percentage of body weight, a 2-fold increase was observed indicative of marked hypertrophy. The depletion of the coenzyme pyridoxal-5'-phosphate from these tissues was extensive (heart 48%, lungs 85%, and kidneys and adrenals 88%.) The extent of loss of the coenzyme from the tissues suggests possible functional changes.

Adrenal Glands↗
PubMed1976

In vivo incorporation of glucose carbon into brain and liver proteins in biotin-deficient rats.

The in vivo utilization of D[U-14C]glucose with particular reference to its incorporation into brain and liver proteins was studied in biotin-deficient rats. The data show a significant reduction in the incorporation of glucose carbon into brain and liver proteins. A disturbance in the intermediary metabolism of glucose to be one of the factors responsible for the decreased incorporation of the label into proteins in biotin deficiency.

Animals↗
PubMed1976

Enzymatic microassay of pyridoxal-5'-phosphate using L-tyrosine apodecarboxylase and L-(1-14C) tyrosine.

A microassay for pyridoxal-5'-phosphate (PLP) is described, which incorporates both the enzymatic and radioisotopic techniques. The method is based upon the stoichiometric decarboxylation of L-(1-14C) tyrosine by L-tyrosine apodecarboxylase and PLP. This method is an extensive modification of the ones reported by us previously, the main features of this present method being the ease of preparation of the enzyme extract and the substrate, elimination of the preincubation period and shortening of the 14CO2-trapping step. The assay as described here is rapid, highly sensitive and specific.

Apoenzymes↗
PubMed1975

Avoidance behavior in vitamin B-6 deficient rats.

Pyridoxine deficiency was induced during the postweaning period in infant and young adult male rats and the effects on active avoidance and escape learning were studied. Five weeks of pyridoxine deficiency was sufficient to produce a deficit in active avoidance learning in the postweanling animals, whereas up to 10 weeks of deficient diet ingestion produced no effect on young adult animals. Mild motor impairment was produced in the young pyridoxine-deficient rats but the avoidance learning deficit could not be explained away on this basis, because a deficit in passive avoidance was also produced by the deficiency. Reversal of the deficiency by pyridoxine injection restored the active avoidance learning to normal within 1 week.

Age Factors↗
PubMed1975

The effect of pyridoxine hydrochloride on blood serotonin and pyridoxal phosphate contents in hyperactive children.

The contents of serotonin (hydroxytryptamine) and pyridoxal phosphate (PLP) in the blood of 11 hyperactive children and 11 controls were determined on an outpatient basis. A significant decrease in serotonin content was found in blood samples from hyperactive patients as compared with controls. There were no differences in PLP content of blood between the two groups. Four children were selected for a study of the effects of pyridoxine hydrochloride (vitamin B6) on low serotonin levels. Oral doses of pyridoxine resulted in an appreciable increase in the serotonin content and a very large increase in the PLP content of blood in these hyperactive patients.

Adolescent↗
PubMed1975

Platelet monoamine oxidase in children with infantile autism.

Platelet monoamine oxidase activity was measured in 9 autistic subjects and 9 controls. There were no significant differences in the rates of metabolism of 5-hydroxytryptamine, dopamine or tyramine between the two groups, although the rate of metabolism of tyramine was more rapid than 5-hydroxytryptamine or dopamine within each group. It is concluded that the data presented do not support the view that measurement of platelet monoamine oxidase can be used as a biochemical index to aid in the clinical diagnosis of infantile autism.

Adolescent↗
PubMed1973

Effects of pyridoxine deficiency and DL-p-chlorophenylalanine administration to rats on 5-hydroxytryptamine and noradrenaline concentrations in brain and 5-hydroxytryptamine concentration in blood.

Pyridoxine deficiency in post-weanling rats caused a marked decrease in body weight and a small but significant decrease in brain weight. Although the concentration of circulating 5-hydroxytryptamine was markedly decreased, the concentrations of 5-hydroxytryptamine and noradrenaline in the brain were not affected. p-Chlorophenylalanine, an inhibitor of 5-hydroxytryptamine synthesis, decreased the 5-hydroxytryptamine content of brain to very low values in both the deficient and control animals, whereas the noradrenaline contents were not appreciably affected. The concentration of 5-hydroxytryptamine in blood, the origin of which is primarily gastrointestinal, was decreased only in the controls but not in the deficient animals after p-chlorophenylalanine treatment. These results suggest that whereas l-tryptophan hydroxylase (EC 1.14.3.2) is rate-limiting in the brain as has been reported by others, the pyridoxal 5'-phosphate-dependent enzyme 5-hydroxytryptophan decarboxylase (EC 4.1.1.28) may be more important in the gastrointestinal tract in the regulation of 5-hydroxytryptamine synthesis.

Animals↗