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Biomedical subjects

A Vinik

Publications and source records attributed to A Vinik.

8 recordsLinked to original sources
PubMed1977

The effects of TRH on prolactin, plasma renin activity, water and electrolyte excretion in normal males.

The effect of TRH induced secretion of TSH and prolactin (hPrl) on plasma renin activity (PRA), water and electrolyte excretion, was studied in 7 normal males before and after an intravenous injection of 2 ml normal saline or 200 microgram TRH. Plasma hPrl and TSH rose significantly (p less than 0.01) in all 7 subjects after TRH but not after saline injection. No significant differences in the hourly excretion of sodium, potassium and free water clearance were noted before and after either saline or TRH injection. Mean PRA values of the 7 subjects were similar after either the 2 ml saline of TRH injection. Our results indicate that despite a correlation between basal hPrl and sodium excretion as well as free water clearance, acute TRH induced elevation of hPrl is not associated with changes of urinary sodium and potassium excretion, free water clearance and PRA in normal males. These findings provide some evidence against a direct osmoregulatory role of hPrl in man.

Adult↗
PubMed1975

The effect of prolonged lithium carbonate administration on the thyrotrophin and prolactin response to thyrotrophin-releasing hormone.

Thyrotrophin (TSH) and prolactin (PRL) responses to intravenous thyrotrophin-releasing hormone (TRH) were measured in euthyroid patients suffering from psychiatric disease on long-term lithium carbonate (LC) and phenothiazine therapy. These responses were retested after oral tri-iodothyronine (T3) 120 mug/day had been given for a week. The raised basal TSH and the suppression of the exaggerated responses to TRH by T3 found in some of the patients suggest a mild disturbance of thyroid function in patients on long-term LC therapy, even in the face of clinical euthyroidism and otherwise normal thyroid function. Basal serum PRL levels and the responses to TRH were elevated in 2 of 5 patients, probably associated with phenothiazine administration. In all 5, a moderate blunting of the PRL responses after TRH was produced by T3. The suppressive effect of T3 on TRH-induced PRL responses was unexpected and suggests a modifying role of thyroid hormones on PRL secretion, although further studies are needed to confirm this possibility.

Female↗
PubMedDate not supplied

Factors controlling pancreatic islet neogenesis.

We have established a model in which cellophane wrapping induces reiteration of the normal ontogeny of beta-cell differentiation from ductal tissue. The secretion of insulin is physiologic and coordinated to the needs of the animal. Streptozotocin-induced diabetes in hamsters can be "cured" at least half the time. There appears to be activation of growth factor(s) within the pancreas, acting in an autocrine, paracrine, or juxtacrine manner to induce ductal cell proliferation and differentiation into functioning beta cells. Given the results of our studies to date, it does not seem premature to envisage new approaches to the treatment of diabetes mellitus. Identification of the factor(s) regulating islet-cell proliferation and differentiation in our model may permit islets to be grown in culture. This concept could be extended to induce endocrine cell differentiation in vitro as well. Furthermore, islet-cell growth factors could be used to provide "trophic support" to islet transplants as a means of maintaining graft viability. There may also be greater scope for gene therapy when the growth factor(s) have been isolated, purified, sequenced, and cloned.

Animals↗