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Biomedical subjects

S Handwerger

Publications and source records attributed to S Handwerger.

At least 163 records · Page 9Linked to original sources

Serum immunoreactive somatomedin-C is elevated late in pregnancy.

The concentrations of immunoreactive somatomedin-C (Sm-C) in the sera of women with uncomplicated pregnancies were found to be progressively higher as the duration of gestation increased. Between 19 and 42 weeks of gestation, there was a significant correlation between serum Sm-C concentration and duration of gestation. A striking decline in Sm-C was observed following delivery. While the data are too preliminary to elucide the mechanisms for the raised Sm-C, the concurrent increase in Sm-C and human placental lactogen (hPL) raises the possibility that hPL may mediate the increment in Sm-C.

Adult↗

Prolactin-secreting pituitary microadenoma: detection and evaluation.

Eleven women with secondary amenorrhea associated with hyperprolactinemia were studied. Base line evaluations, visual field determinations, and routine sella turcica x-rays were normal. Prolactin-secreting pituitary microadenomas were found in all of the patients only after further diagnostic studies were carried out. These studies included polytomography of the sella turcica; dynamic pituitary testing of growth hormone reserve, adrenocorticotropic hormone reserve, and gonadotropin reserve; and prolactin suppression with L-dopa. The early diagnosis of a small prolactin-secreting adenoma may be possible if several diagnostic criteria are utilized. The most sensitive diagnostic indices available are (1) polytomography, (2) the magnitude of the plasma prolactin elevation, and (3) the failure to suppress prolactin secretion with L-dopa. Our findings emphasize the importance of an extensive evaluation of all women with amenorrhea associated with hyperprolactinemia.

Adenoma↗

Treatment of functional amenorrhea-galactorrhea with 2-bromoergocryptine.

The present study was undertaken to investigate not only the effectiveness of bromoergocryptine therapy in 13 women with amenorrhea-galactorrhea and hyperprolactinemia without evidence of organic pathology, but also to assess the value of pretreatment evaluation in predicting the response to therapy. Sella turcica tomography, base line serum follicle-stimulating hormone, luteinizing hormone (LH), thyroid-stimulating hormone, T4, plasma cortisol levels, and the growth hormone reserve were normal in all patients. The pretreatment administration of LH-releasing factor (LRF) (100 microng subcutaneously) resulted in either a normal or excessive release of LH. On bromoergocryptine therapy, cyclic menses were reintiated in 10 of the women, while conception occurred prior to reinitiation of menses in the remaining three women. The time required for resumption of menses or conception on therapy correlated well with the magnitude of gonadotropin response to LRF. No correlation was seen with pretreatment prolactin levels nor with the degree of suppression of prolactin during bromoergocryptine therapy. In four women the mean prolactin levels during therapy were above normal, and in one patient prolactin levels approached pretreatment values during therapy. The initiation of cyclic menses despite continued hyperprolactinemia may indicate a possible direct effect of bromoergocryptine on hypothalamic LRF secretion as a partial explanation for its therapeutic action. On discontinuation of bromoergocryptine therapy, serum prolactin levels rapidly returned to pretreatment values or higher in all of the patients studied. In contrast to previous studies in which amenorrhea recurred in all patients after discontinuation of therapy, three of our patients maintained cyclic menses despite continued hyperprolactinemia. The recurrence of hyperprolactinemia after discontinuation of bromoergocryptine would indicate a persistent autonomy of the mechanisms involved. Periodic endocrine evaluation will be necessary to substantiate the presence or absence of pituitary microadenoma in these women.

Adult↗

Ovine placental lactogen induces somatomedin: a a possible role in fetal growth.

Ovine placental lactogen (oPL) and bovine growth hormone (bGH) increase the circulating concentration of somatomedin in hypophysectomized rats. This finding indicates that some of the somatotropic properties of oPL may be due to the induction of somatomedin and raises the possibility that oPL has a role in the control of fetal growth.

Animals↗

Failure of L-tryptophan to stimulate prolactin secretion in man.

The effect of oral L-tryptophan (90 mg/kg BW) on prolactin secretion in eight normal women studied either in the early or late follicular phase of the menstrual cycle was compared to the effect of a placebo alone. Plasma prolactin levels were measured before and at frequent intervals over a period of 240 min after the administration of the amino acid or placebo. Plasma free L-tryptophan concentrations were determined prior to and 60 min after ingestion of the amino acid in two of the women. Despite a 25-fold increase in plasma free L-tryptophan levels following the administration of this amino acid, the prolactin response to L-tryptophan was not significantly different from a placebo.

Adult↗

Studies on ovine placental lactogen secretion by homologous radioimmunoassay.

The concentrations of ovine placental lactogen (oPL) have been determined in maternal plasma, umbilical cord plasma, and allantoic fluid by an homologous radioimmunoassay for oPL which is sensitive to 0-1 ng hormone. Ovine placental lactogen was first detected in maternal plasma at 41-50 days of gestation and reached a peak concentration of 2547 +/- 226 (S.E.M.) ng/ml at 121-130 days in ewes with singleton gestations. The oPL concentration in cord plasma was 336-4 +/- 60-3 ng/ml and in allantoic fluid was 29-6 +/- 6-4 ng/ml. After surgical removal of the placenta, oPL disappeared from maternal plasma with a half-life of 29-1 +/- 1-3 min.

Allantois↗

Localization and specificity of binding of subprimate placental lactogen in rabbit tissues.

A search for specific placental lactogen binding was undertaken in tissues obtained from late pregnant rabbits using the placental lactogens from sheep, cows, and human beings. 125I-labeled ovine lactogen exhibited highest specific binding to the adrenal gland (57.8%), followed by liver (21.5%), ovary (19.9%), mammary gland (15.9%), uterus (12.2%), kidney (8.8%), brain (8.5%), and adipose tissue (7.9%). In liver and mammary gland, the displacement curves for ovine and human lactogen were identical to that for bovine prolactin, indicating that they share the same receptor site. Although the displacement curve for bovine lactogen was parallel to that of the other lactogens the bovine hormone is less active in the radioreceptor assay.

Adrenal Glands↗

Ovine placental lactogen: acute effects on intermediary metabolism in pregnant and non-pregnant sheep.

The intravenous administration of ovine placental lactogen to pregnant and non-pregnant sheep produced significant acute decreases in plasma free fatty acid, glucose and amino nitrogen concentrations. Plasma insulin concentrations decreased 1 h after administration of ovine placental lactogen and then increased significantly above baseline concentrations. The results suggest that, like human placental lactogen, ovine placental lactogen is important in the modulation of intermediary metabolism during pregnancy. The sheep is an excellent animal model for the investigation of the physiology of placental lactogen.

Amino Acids↗

Prolactin after gonadotropin-induced pregnancy.

Prolactin levels during a gonadotropin-induced pregnancy have not been previously reported. A patient with Forbes-Albright syndrome is described. She received radiation therapy, with cessation of her galactorrhea, but she remained amenorrheic. Three years after irradiation, a pregnancy was successful induced with human menopausal gonadotropins and human chorionic gonadotropin. Prolactin levels determined prior to gonadotropin therapy, during an insulin hypoglycemia stimulation test, serially during pregnancy, and postpartum during lactation are presented. These levels are compared with the previously reported levels for basal prolactin, response to insulin hypoglycemia, pregnancy, and lactation. Possible etiologies for the abnormal values and responses obtained from investigation of this patient are discussed.

Adult↗

Development of the sheep as an animal model to study placental lactogen physiology.

Ovine placental lactogen, purified from term sheep cotyledons, has been found to have chemical and biologic properties similar to those of human placental lactogen, ovine growth hormone, and ovine prolactin. OPL stimulates lactation in vivo and in vitro and binds to prolactin and growth hormone membrane receptors. Its binding to growth hormone receptors is approximately 20 times greater than that of hPL, suggesting that its somatotrophic potency is greater than that of hPL. Preliminary in vivo studies in the sheep indicate that oPL affects maternal carbohydrate, lipid, and protein metabolism and that its effects are, in part, similar to those of hPL and growth hormone.

Animals↗