Biomedical subjects

P Beck

Publications and source records attributed to P Beck.

At least 127 records · Page 7Linked to original sources

PubMed1975

Growth hormone release after synthetic 1-24 ACTH: effects of estrogen and sex.

Recent reports have demonstrated that growth hormone (GH) is inconsistently released after intravenous administration of synthetic 1-24 ACTH. This study was designed to evaluate the role of estrogens in mediating this response. 250 mug of synthetic 1-24 ACTH were administered to 8 men in 12 studies and 6 women in 11 studies. None of the men exhibited a rise in GH after 1-24 ACTH, while the women exhibited a significant increase. Pretreatment of 5 of these men with 100 mug of ethinyl estradiol daily for 3 days did not alter GH response from the initial studies. Pretreatment with 10 mg of diethylstilbesterol daily for 3 days, however, resulted in a rise in GH which was similar to the female group. It is concluded that the variable GH responses to synthetic 1-24 ACTH may be in part due to prevailing concentrations of sex steroids and their effect on the hypothalamic-pituitary GH release mechanism.

Adrenocorticotropic Hormone↗

PubMed1975

Twenty-four-hour prolactin profiles in normal and disease states: failure of thyroxine to modify prolactin secretion.

In order to assess the role of thyroid hormone on physiologically and pharmacologically induced prolactin (PRL) secretion, serum PRL concentrations were measured in 4 normal women and 4 women with various endocrinopathies before, and 4 to 6 days following, the ingestion of L-thyroxine (T4). A single 1.5 to 3.0 mg dose of oral T4 produced approximately a 2-fold increase in serum T4. Exogenous T4 did not significantly alter the mean concentration, or the pattern of PRL secretion during a 24-h interval in either normal individuals or 3 patients with galactorrhea. The lactating patients had elevated basal PRL levels and a blunted secretory response to intramuscular chlorpromazine; however, neither fasting PRL nor the peak response to chlorpromazine was altered by T4. L-Dopa suppression of serum PRL was not significantly influenced by T4 in these patients. In conclusion, PRL secretion remained unaltered after the administration of thyroxine in doses sufficient to produce approximately a 2-fold increase in serum T4. This challenges the concept that T4 and TRH are important physiologic regulators of PRL secretion.

Adult↗

PubMed1975

Mutual modification of glucose-stimulated serum insulin responses in female rhesus monkeys by ethinyl estradiol and nortestosterone derivatives.

Changes in iv glucose tolerance (IVGTT) and serum insulin responses to glucose infusion have been measured in intact female rhesus monkeys treated per os with norethindrone or medroxyprogesterone acetate (500 mug/day) both alone and in combination with mestranol or ethinyl estradiol (10 mug/day) orally for 3 weeks. When administered as the sole contraceptive steroid, neither norethindrone, medroxyprogesterone acetate, mestranol, or ethinyl estradiol produced consistent changes in fasting serum insulin or glucose concentration, mean intravenous serum glucose disappearance rates (K) or mean integrated serum insulin response to glucose (sigmal40). By contrast, concurrent administration of norethindrone with mestranol or ethinyl estradiol resulted in a significant increase in the fasting serum insulin concentration and the mean sigmal40. An increase in the mean K was also observed after norethindrone + mestranol. These results show that synthetic estrogens have the ability to potentiate the metabolic effects of norethindrone. However, the improvement in glucose tolerance produced in rhesus monkeys by concurrent mestranol + norethindrone treatment was marginal because of wide variation in glucose assimilation rates uncer control conditions. Thus, the IVGTT in the rhesus monkey appears to have limited use as a model for studying glucose homeostasis in man.

Administration, Oral↗

PubMed1975