PubMed Health⌕ Search

Biomedical subjects

H Lipner

Publications and source records attributed to H Lipner.

At least 19 recordsLinked to original sources
PubMed1984

The role of inhibin in adult male rats: the effect of inhibin deficiency and androgen antagonism on serum and pituitary gonadotrophins.

We examined the ability of inhibin-F contained in porcine follicular fluid (pFF) to regulate serum gonadotrophins in male rats made deficient in endogenous inhibin and unable to respond to normal endogenous androgen levels. Efferent duct ligation (EDL) effected endogenous inhibin deficiency and the anti-androgen flutamide (F) (13.4 mg/dose, sc once per day) raised the set point for androgen control of the hypothalamus to a level intermediate between the intact and castrate serum gonadotrophin levels. EDL, F and EDL + F caused serum FSH levels to rise and administration of pFF (2 ml per day) suppressed the elevated serum FSH levels of these experimental models to intact animal levels. Though EDL had no effect on serum LH, F increased the serum LH levels and EDL plus F increased them further. Treatment with pFF suppressed the serum LH to intact levels. EDL rats had slightly increased serum androgen (6 ng/ml) but F and EDL + F treated rats had very greatly increased serum androgen concentrations (22 and 32 ng/ml, respectively) which treatment with pFF suppressed to intact levels. Pituitary FSH was increased by EDL and LH was increased by F. In both cases, the increased pituitary gonadotrophins were suppressed by treatment with pFF. We conclude that inhibin regulates synthesis and secretion of FSH and secretion of LH.

Anilides↗
PubMed1984

Coagulation and fibrinolytic responses to exercise and cold exposure.

This study examined the effect of acute cold exposure on coagulation (PTT) and fibrinolysis (ELT), and the effect of cooling on subsequent exercise-induced coagulation and fibrinolytic responses. Ten male volunteers were tested at 5 degrees C and 28 degrees C on alternate days. Each subject began by sitting quietly for 60 min. Each then exercised on a cycle ergometer at 50 W for 5 min followed by 150 W for 10 min. Venous blood samples were taken before rest, after rest, and after exercise for each temperature on each of the two days. PTT, ELT, and hematocrit (HCT) were determined at each interval. Rectal temperature (Tre) and mean skin temperature (Tsk) were assessed at 15-min intervals throughout. Tsk was stable under neutral conditions but declined rapidly in the cold environment. Tre response was more complex but was significantly different for one contrast only (CE less than NE). ELT was shortened to 74, 62, and 44% while HCT increased to 107, 107, and 111% of pretest values for CR, NE, and CE, respectively. No significant change was noted for PTT. It is concluded that acute cold exposure as well as exercise stress results in an increase in ELT activity of blood; simultaneous enhancement of the coagulation status of the blood in response to stress is not inextricably linked to an elevation of fibrinolytic activity, a result that questions the importance of the Hageman factor dependent pathway between coagulation and fibrinolysis.

Adult↗
PubMed1982

The contribution of gonadostatin (inhibin-F) to the control of gonadotropin secretion in a simulated estrous cycle in steroid-treated ovariectomized rats.

We have examined the contribution of gonadostatin to the control of gonadotropin secretion throughout the rat estrous cycle. The estrous cycle was simulated in rats ovariectomized on diestrus-1, designated day 1 (D-1) by use of low or high level estradiol and progesterone Silastic implants. The steroid implant regimen simulated the major changes of these hormones in the blood during the course of the estrous cycle. Injections of porcine follicular fluid (pFF) were superimposed on this steroid regimen. Four treatment combinations of steroid and pFF or their controls were tested: 1) steroid implants only, 2) pFF only at a constant dose level, 3) steroid implants and pFF injections at a constant dose level, and 4) steroid implants and pFF injections with reduced levels on simulated proestrus. In group 1 both basal and surge release of LH were similar to those in the intact rat, but both basal and surge release of FSH were significantly elevated above levels observed in the intact rat for the respective periods. In group 2 FSH was suppressed to diestrous levels throughout the course of the experiment, with no surge occurring on D-3. Serum LH levels were slightly elevated above diestrous levels (50-150 ng/ml) with no surge. In group 3 serum levels of both gonadotropins were suppressed to diestrous levels on D-1 and D-2, and a steroid-induced, pFF-attenuated surge occurred on the afternoon of D-3. Group 4 had, with a minor variation, proestrous-like FSH and LH surges on D-3 and basal (diestrous) gonadotropin levels during simulated D-1, D-2, and early proestrus. This study supports previous evidence for estradiol and progesterone control of LH secretion and elaborates the control of FSH secretion. The role of gonadostatin and steroids is demonstrated in the negative feedback regulation of FSH secretion.

Animals↗
PubMed1979

The dissociation and separation of bovine adenohypophysial cells.

Bovine adenhypophysial tissue was dissociated by sequential enzymatic incubation in a continuous flow system. Dispersed cells separated into discrete fractions after centrifugation in isopycnic bovine serum albumin gradients. The dispersed and separated cells were prepared for microscopic identification and differential counts by centrifugal cytology. Radioimmunoassays for LH, FSH, TSH, and Prl were used to corroborate the differential counts and determine the homogeneity of the fractions. The thyrotrophs banded at an average density (rho) of 1.0417, the FSH-secretory cells at rho = 1.0597, the LH-secretory cells at rho = 1.0458, and the Prl-secretory cells at rho = 1.0126. A 7-16 fold enrichment of different cell populations was possible. In bovine hypophyses each hormone appears to be formed by specific cells: the average TSH concentrations of the thyrotrophs were 5.1 pg/cell for LH- and FSH concentration were 4.7 and 4.9 pg/cell for LH- and FSH-secreting cells, respectively. The average Prl concentration was 4.9 pg/cell for Prl-secreting cells.

Animals↗
PubMed1978

Responses to intensive training and methandrostenelone administration. I. Contractile and performance variables.

The purpose of this study was to investigate the effects of methandrostenelone (Dianabol) on contractile and performance variables in the rat. Thirty-six male Sprague Dawley rats 90 days old were divided into sedentary and exercise groups; they were further subdivided into Dianabol (0.35 mg/kg/day) treated and untreated groups. The exercise groups underwent a program of high intensity training 7 days/week for 6 weeks. Training produced changes in isometric force-time characteristics indicating increased production of tension. Performance test scores increased significantly from 3 weeks to 6 weeks. Performance by exercise and exercise with Dianabol groups was indistinguishable. It is concluded that Dianabol did not significantly alter the adaptations of the rat to high intensity training.

Analysis of Variance↗
PubMed1978

Responses to intensive training and methandrostenelone administration: II. Hormonal, organ weights, muscle weights and body composition.

The hormonal levels of the gonadotropins, the weight of selected organs and of the triceps surae as well as body composition were determined in Sprague Dawley rats at 3 and 6 weeks after intensive training with or without a methandrostenelone (Dianabol) supplement (0.35 mg/kg/day). The controls were sedentary rats of similar age and weight at the start of the experiment. The dianabol treated rats in the sedentary and exercise groups had a depression of plasma LH levels. There were no differences in body weight, specific gravity, lean body weight, fat or %fat between the two trained groups. Dianabol had no apparent effect on the measured parameters other than a depression of LH.

Analysis of Variance↗
PubMed1978

Menstrual dysfunction of patients undergoing chronic hemodialysis.

This study group consisted of 10 female patients undergoing chronic hemodialysis. The duration of their illness was from 10 months to 8 years. Nine of the 10 had been undergoing hemodialysis for more than 1 year. Their menstrual patterns have been investigated, specifically with regard to menstrual history, gonadotropin and progesterone levels, and basal body temperature. Nine of the 10 patients had had regular menses prior to their renal illnesses. All patients became amenorrheic during and after hemodialysis with the exception of one patient who became hypermenorrheic. The gonadotropin levels were as follows: the luteinizing hormones were high-normal and the follicle stimulating hormones were low, almost to a hypogonadotropic range; progesterone level coupled with the basal body temperature showed no evidence of ovulatory cycles, except in one case.

Adult↗
PubMed1976

A model system for studying inhibin.

We report here a sensitive model for studying inhibin-like activity in crude ovine testicular extracts (CoTE). The administration of CoTE in 25-100 mg amounts to 35-day-old immature male rats, orchidectomized just prior to use, resulted in the prevention of a rise in plasma FSH levels, seen 10 h post-treatment. In a second model, CoTE was injected at 1000 h of day 35 to a group of rats that was castrated 12-24 h prior to injection, and the animals were sacrificed 6 h later; plasma FSH levels were found to be significantly suppressed. CoTE, administered subcutaneously, both in multiple doses and as a single injection, was found to be equally effective. A single injection suppressed FSH levels within 3-6 h while LH levels were unaffected. The suppressive effect was dose-dependent, reaching a maximum value at doses of 100 mg CoTE and above. FSH levels could not be suppressed below the tonic level, either by the administration of a single large dose of CoTE, or by repetitive injections of maximal doses of CoTE at 3 h intervals. The suppression in FSH levels caused by a single injection of CoTE waned with time and totally disappeared by 36h. CoTE was prepared by the heat treatment (55 C for 30 min) of an aqueous extract of ovine testis, followed by centrifugation and ether extraction of the supernatant. The aqueous layer was then dialyzed and lyophilized. The lyophilized material was found to be free of testosterone, as measured by a specific radioimmunoassay, indicating that the active factor is a heat-stable, lyophilizable, nondialyzable material, free of contamination by testosterone and probably by other steroids.

Animals↗