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Biomedical subjects

S Bhatnagar

Publications and source records attributed to S Bhatnagar.

At least 109 records · Page 6Linked to original sources
PubMed1988

Stress-induced occupancy and translocation of hippocampal glucocorticoid receptors.

Using an exchange assay for glucocorticoid receptors, we found that immobilization stress resulted in a approximately 50% translocation of receptors (i.e. receptors assumed to be chromatin bound) from soluble fractions prepared from hippocampal tissue. The increased hormone-receptor signal persisted for about 2-4 h following the termination of the stressor. This time course is consistent with the known temporal pattern for the negative feedback of glucocorticoids on adrenocortical activity.

Adrenalectomy↗
PubMed1988

Effect of neonatal handling on age-related impairments associated with the hippocampus.

In rats, an environmental manipulation occurring early in life resulted in changes in the adrenocortical axis that persisted throughout the entire life of the animals and attenuated certain deficits associated with aging. Rats handled during infancy had a permanent increase in concentrations of receptors for glucocorticoids in the hippocampus, a critical region in the negative-feedback inhibition of adrenocortical activity. Increased receptor concentrations led to greater hippocampal sensitivity to glucocorticoids and enhanced negative-feedback efficacy in the handled rats. Thus, at all ages tested, rats that were not handled secreted more glucocorticoids in response to stress than did handled rats. At later ages, nonhandled rats also showed elevated basal glucocorticoid levels, with the result that there was a greater cumulative exposure to glucocorticoids in nonhandled rats. Increased exposure to adrenal glucocorticoids can accelerate hippocampal neuron loss and cognitive impairments in aging. Hippocampal cell loss and pronounced spatial memory deficits emerged with age in the nonhandled rats, but were almost absent in the handled rats. Previous work showed that glucocorticoid hypersecretion, hippocampal neuron death, and cognitive impairments form a complex degenerative cascade of aging in the rat. The present study shows that a subtle manipulation early in life can retard the emergence of this cascade.

Aging↗
PubMed1984

Agrammatism on inflectional bound morphemes: a case study of a Hindi-speaking aphasic patient.

In this report, we discuss a Hindi agrammatic patient who exhibited greater difficulty with the production of inflectional bound morphemes than with function words. The patient retained the metalinguistic judgement to differentiate function words with semantic content, such as postpositions which mark case functions in Hindi. His impaired ability to produce bound inflections also affected his retrieval of verbs; this failure to retrieve verbs was not due to anomia. Further neurolinguistic analyses of synthetic languages would seem likely to extend our understanding of syntactic processes.

Aphasia↗
PubMed1983

Language in the nondominant right hemisphere.

Language function was evaluated in the right nondominant hemisphere in three patients undergoing cortical resection for intractable seizures. Three linguistic tests were given during electrical stimulation of the cortex. They represented three different levels of language complexity from lowest to highest as follows: task 1, object naming; task 2, sentence completion; and task 3, responsive naming. The greatest number of linguistic errors occurred with sentence completion. No linguistic errors were made on the most complex task. Wada's test in the right nondominant hemisphere did not impair function, whereas in the left dominant hemisphere it did. To make these seemingly incompatible observations acceptable, we speculate that there is a right nondominant language system that is anatomically and functionally tied to the left dominant system. Under normal conditions it is passively involved and its integrity is not essential to the function of the left dominant language system.

Adult↗