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Biomedical subjects

R A Vigersky

Publications and source records attributed to R A Vigersky.

At least 19 recordsLinked to original sources
PubMed1987

Exaggerated gonadotropin response to luteinizing hormone-releasing hormone in amenorrheic runners.

Most studies of exercise-induced amenorrhea have compared amenorrheic athletes (usually runners) with sedentary control subjects. Such comparisons will identify hormonal changes that develop as a result of exercise training but cannot determine which of these changes play a role in causing amenorrhea. To obviate this problem, we assessed reproductive hormone status in a group of five amenorrheic runners and compared them to a group of six eumenorrheic runners matched for body fatness, training intensity, and exercise performance. Compared to the eumenorrheic runners, the amenorrheic runners had lower serum estradiol concentrations, similar basal serum luteinizing hormone and follicle-stimulating hormone concentrations, and exaggerated responses of serum gonadotropins after administration of luteinizing hormone-releasing hormone (100 micrograms intravenous bolus). Serum prolactin levels, both basally and after thyrotropin-releasing hormone administration (500 micrograms intravenous bolus) or treadmill exercise, was similar in the two groups, as were serum thyroid function tests (including thyrotropin response to thyrotropin-releasing hormone). Changes in serum cortisol levels after short-term treadmill exercise were similar in both groups, and serum testosterone levels increased after exercise only in the eumenorrheic group. In neither group did such exercise change serum luteinizing hormone, follicle-stimulating hormone, or thyrotropin levels. We concluded that exercise-induced amenorrhea is not solely related to the development of increased prolactin output after exercise training. The exaggerated gonadotropin response to luteinizing hormone-releasing hormone seen in amenorrheic runners in comparison with matched eumenorrheic runners is consistent with a hypothalamic etiology for the menstrual dysfunction, analogous to that previously described in "stress-induced" or "psychogenic" amenorrhea.

Amenorrhea↗
PubMed1987

Amenorrhea in Olympic marathon runners.

Women who exercise heavily may develop secondary amenorrhea. Since the mechanism of so-called "runner's amenorrhea" has not been conclusively established, the authors examined the occurrence of amenorrhea in one of the most intensively exercising groups of female runners in the United States (average, 70 miles/week): those women participating in the marathon trials for the 1984 Olympics. Nineteen percent of these Olympic runners were amenorrheic. When compared with eumenorrheic marathon runners, these amenorrheic runners were significantly (P less than 0.05) younger (24.8 +/- 1.2 [standard error of the mean] versus 30.8 +/- 0.8 years), lighter (108.4 +/- 2.5 versus 114.6 +/- 1.7 lb), and leaner (11.2 +/- 0.5 versus 12.5 +/- 0.3% body fat). There were no differences between the two groups in weekly training mileage, proportion completing the marathon trial, finishing time, basal serum prolactin, or postmarathon serum prolactin. Although basal serum cortisol was slightly higher in the amenorrheic group (26.6 +/- 0.8 versus 22.3 +/- 0.7 micrograms/dl; P less than 0.05), postmarathon serum cortisol was similar in the two groups. This study supports the concept that training intensity above a certain threshold seems to have little effect on the development of runner's amenorrhea, and vigorously training national caliber marathon runners have a lower incidence of amenorrhea than previously predicted.

Adult↗
PubMed1986

Nutritional survey of highly trained women runners.

Mean daily intakes from 3-day dietary records for calories, energy-providing nutrients, and selected minerals were calculated for 51 highly trained women runners. Selected blood constituents relating to mineral status were also measured. Intakes of calcium, magnesium, iron, and copper were above the amounts recommended by the National Research Council whereas zinc intake was below the recommended dietary allowances (RDA). Caloric intakes, although above the RDA for sedentary women, appeared low for women running 10 miles/day. Concentrations of serum ferritin and plasma zinc were indicative of marginal iron and zinc status in many of the women. Whether the nutrient content of the diets consumed by these women is adequate relative to energy output or whether training lowers nutrient requirements by enhancing metabolic efficiency will require further investigation.

Adult↗
PubMed1986

Comparative antiandrogenic potency of spironolactone and cimetidine: assessment by the chicken cockscomb topical bioassay.

Spironolactone and cimetidine are effective antiandrogens in vivo, although they differ by five orders of magnitude in affinity for androgen receptors in vitro. To explore this discrepancy, we directly compared the antiandrogenic potency of these two compounds in vivo using the chicken cockscomb topical bioassay. In this assay, the growth of the androgen sensitive cockscomb of immature chicks after stimulation by various doses of androgen (dihydrotestosterone 5, 20, or 100 micrograms/day sc) is inhibited by antiandrogens in cream vehicle applied topically to the cockscomb itself. At low levels of androgen stimulation (5 micrograms/day), 0.5% topical cimetidine produced maximal suppression of cockscomb growth, while at high levels of androgen stimulation 100 micrograms/day), topical cimetidine in concentrations as high as 4% did not suppress cockscomb growth. In contrast, topical spironolactone in concentrations as low as 0.06% produced maximal inhibition of cockscomb growth at all androgen doses. Using an intermediate androgen dose (20 micrograms/day), the minimally effective antiandrogenic concentration of topical cimetidine was between 0.5 and 1.0%, while that for topical spironolactone was less than 0.001%. We conclude that the chicken cockscomb topical bioassay is a useful method for assessing relative potency of antiandrogens. With this method, spironolactone appears to be at least 500 times as strong an antiandrogen in vivo as cimetidine.

Administration, Topical↗
PubMed1986

Nutritional intakes and status of highly trained amenorrheic and eumenorrheic women runners.

This study was conducted to determine whether nutritional status contributes to the amenorrhea associated with long distance running. Dietary intakes and biochemical measures of nutritional status were compared in highly trained amenorrheic (AM) and eumenorrheic (EU) women runners matched for height, weight, percent fat (11% to 12%) and training distance (113 km/week). Serum estradiol (E2) (EU, 104.7 pg/ml, versus AM, 22.5 pg/ml) and cortisol (EU, 22.4 micrograms/dl, versus AM, 26.6 micrograms/dl) concentrations differed between the two groups. Three-day dietary records revealed that fat intake by AM runners was significantly lower than by EU runners (EU, 97 gm/day, versus AM, 66 gm/day). AM runners consumed large amounts of vitamin A activity, probably in the form of B-carotene, and fairly high quantities of crude fiber. Zinc intake by AM runners was well below the recommended dietary allowances (RDA), compared with EU runners (EU, 15.4 mg, versus AM, 10.9 mg). Further, plasma zinc tended to be lower for the AM runners (EU, 85.7 micrograms/dl, versus AM, 81.2 micrograms/dl). It was concluded that the potential contributions of dietary fat, B-carotene, and zinc to inducing changes in menstrual function and the metabolism of certain hormones should be investigated.

Adult↗
PubMed1985

Hypogonadotropic hypogonadism in nephrotic rats: increased sensitivity to negative feedback effects of testosterone.

Pituitary-testicular function was examined in adult male rats with aminonucleoside-induced nephrotic syndrome as a model for similar disease in humans. Nephrotic rats developed androgen deficiency, as manifested by decreased prostate and seminal vesicle weights, lower serum total and free testosterone levels, and reduced testosterone release from testes incubated in vitro. Despite hypoandrogenism, the weight and histologic appearance of the testes (light microscopy) were not affected in nephrotic rats. This androgen deficiency seemed to be a consequence of decreased gonadotropin output rather than primary testicular failure, since both pituitary gonadotropin content and serum gonadotropin levels (basally and after luteinizing hormone releasing factor; LHRH) were reduced in nephrotic rats. In addition, the percentage increase in testosterone release by testes incubated in vitro after addition of exogenous gonadotropin was similar in nephrotic and control groups. However, gonadotropin output in nephrotic rats was not impaired in the absence of testis, since no reduction was seen in either post-castration serum gonadotropin levels in vivo or gonadotropin release from pituitaries incubated in vitro. This presumed inhibitory effect of the testis on gonadotropin output in nephrotic rats was confirmed directly by demonstrating an increased sensitivity to testosterone-mediated suppression of gonadotropins in castrate animals in vivo. The presence or absence of albumin also seemed to modulate the suppressive effect of testosterone on gonadotropin output from normal pituitaries incubated in vitro. We conclude that nephrotic male rats develop hypogonadotropic hypogonadism secondary to an increase in sensitivity of the pituitary to the negative feedback effects of testosterone.

Androgens↗
PubMed1985

Microplate solid-phase radioimmunoassay for rat prolactin.

A rat prolactin solid-phase radioimmunoassay has been developed that uses 96-well microtiter plates with removable wells to which the antibody is firmly adsorbed, resulting in a solid-phase antibody. Antigen as either reference or unknown competes with radioactivity labeled antigen for binding sites on the solid-phase antibody. After immunoreaction, free antigen is removed by washing the wells with phosphosaline solution. The solid-phase antibody-antigen complex is counted for quantitation with data reduction methods currently used in routine radioimmunoassay procedures. This microplate solid-phase radioimmunoassay has several advantages over conventional methods without sacrificing specificity, sensitivity, or accuracy. This method is rapid, compact, economical, easily automated, and could be readily established in other laboratories.

Animals↗
PubMed1984

Low serum thyroxine and high serum triiodothyronine in nephrotic rats: etiology and implications for bioavailability of protein-bound hormone.

Traditionally, it has been thought that the bioavailable fraction of circulating serum hormones, i.e. that which is available for cellular uptake and is physiologically active, is limited to the free (nonprotein bound) hormone. However, recent evidence, based on acute organ uptake of labeled hormone, suggests that the amount of hormone which is bioavailable in vivo may exceed that which is calculated to be free in vitro. To explore the bioavailability of circulating protein-bound thyroid hormones under steady state conditions in vivo, we altered serum thyroid hormone-binding proteins in rats by inducing nephrotic syndrome with puromycin aminonucleoside. Nephrotic rats (serum albumin, 1.1 g/dl) were found to have a marked reduction in serum T4 [2.1 +/- 0.2 (SEM) vs. 6.5 +/- 0.3 microgram/dl; P less than 0.01] and an elevation of serum T3 [141 +/- 8 vs. 51 +/- 2 ng/dl; P less than 0.01]. Estimated T4 production rate was normal in nephrotic rats, and the 3- to 4-fold increase in T4 MCR appeared to account for the marked reduction in serum T4. By contrast, increased serum T3 levels in nephrotic rats reflected both a reduction (55%) in T3 MCR and an increased rate of peripheral conversion of T4 to T3. A circulating inhibitor of T4 binding to serum proteins appeared to be present in nephrotic rats. The changes in the various serum components of thyroid hormone [T4-binding prealbumin (TBPA)-bound, albumin-bound, free] produced by nephrotic syndrome were compared with the corresponding changes in indices of thyroid hormone bioavailability (MCR, urinary excretion, hepatic content, TSH suppression, single pass extraction by liver). These comparisons suggested that nephrotic syndrome results in increased bioavailability of circulating T4 and decreased bioavailability of circulating T3. The bioavailable fraction of circulating T3 in vivo seemed to include both free T3 and that which is albumin bound in vitro. The bioavailable fraction of circulating T4 resembled free T4 more than non-TBPA-bound T4 (= albumin bound + free), although a nephrosis-induced increase in bioavailability of TBPA-bound T4 was also possible. We conclude that nephrotic rats have low serum T4, which is related to accelerated T4 clearance, and high serum T3, which is related both to decreased T3 clearance and increased peripheral conversion of T4 to T3. Under steady state conditions in vivo, bioavailable circulating T3 appears to include both free T3 and the T3 that is bound to albumin in vitro.

Animals↗
PubMed1984

Relationship between pubertal timing and body size in underfed male rats.

A direct connection has been proposed between body size and sexual maturation by the critical body weight and critical body fat hypotheses. To test these theories in male rats, we compared the degree of sexual maturation in animals with reduced growth rate due to undernutrition with that in weight-matched but normally fed rats. Underfed rats had significantly larger prostate, seminal vesicle, and testis weights than the weight-matched normally fed controls at the three time points studied: the early pubertal period (approximate time of onset of rising serum testosterone), late pubertal period (approximate time of appearance of mature spermatids), and young adult period. At the first time point, testes of underfed rats, but not those of normally fed, weight-matched controls, showed mature step 19 spermatids, and serum testosterone was significantly higher in the underfed animals. At all time points, serum LH levels were similar in both groups, while serum FSH levels were significantly lower in the underfed rats at all points. The Lee index, an index of fatness, was significantly lower in the underfed rats. The current study indicates that underfed rats are more sexually mature than normally fed controls of the same weight despite having a lower percentage of body fat. These findings do not support the critical body weight or critical body fat hypotheses of puberty in male rats.

Adipose Tissue↗
PubMed1982

Testicular dysfunction in untreated Hodgkin's disease.

Gonadal function was examined in 19 young men with Hodgkin's disease before therapy and compared with that of 11 men with other malignancies, 13 men with primary testicular failure, and 19 normal men of similar age. Total (p less than 0.01) and free (p less than 0.05) testosterone levels were decreased in Hodgkin's disease. In those with advanced (stage III + IV) and symptomatic (B), Hodgkin's disease serum testosterone levels were indistinguishable from those in primary testicular failure, yet serum levels of luteinizing hormone were normal. Moreover, the acute response of serum testosterone to exogenous human chorionic gonadotropin (HCG) was significantly greater in Hodgkin's disease than in primary testicular failure (p less than 0.03). These data and the finding that basal serum follicle-stimulating hormone levels are significantly lower than normal in Hodgkin's disease (p less than 0.05) suggest that the cause of pretreatment hypogonadism in Hodgkin's disease is not simple primary testicular failure. Total sperm count was decreased in 40 percent of men with Hodgkin's disease but in none of the men with other malignancies (p less than 0.05), suggesting specific seminiferous tubular dysfunction in Hodgkin's disease. However, motility was abnormal in 69 percent of men with Hodgkin's disease and 60 percent of those with other malignancies, suggesting that this is a nonspecific effect of cancer. Serum prolactin levels were significantly higher than normal in Hodgkin's disease (p less than 0.05) but not in other malignancies. Our findings suggests that the cause of testicular dysfunction that is present before treatment of Hodgkin's disease is complex, perhaps involving both pituitary and gonadal abnormalities.

Adult↗
PubMed1982

Testicular reserve of testosterone precursors in primary testicular failure.

To explore the abnormal steroidogenesis in subjects with primary testicular failure, we measured serum levels of testosterone (T) and its precursors androstenedione (delta 4A) and 17-hydroxyprogesterone (17-OHP) in the basal state and after stimulation by human chorionic gonadotropin (hCG) for 4 hours (acute reserve) or 72 hours (chronic reserve). Subjects with primary testicular failure had decreased mean basal serum T, decreased mean chronic T reserve, and absent mean acute T reserve. In contrast, these subjects had normal mean basal serum 17-OHP and delta 4A, normal chronic 17-OHP reserve, and non-zero mean acute 17-OHP and delta 4A reserve, although mean chronic delta 4A reserve was reduced. Heterogeneity of biochemical abnormalities depending on the etiology of testicular failure was apparent. In primary testicular failure, the testicular reserves of the T precursors 17-OHP and delta 4A are better maintained than is the reserve of T itself, raising the possibility that this disorder might be associated with biochemical blocks in conversion of T precursors to T.

Adolescent↗
PubMed1982

The antiandrogenic effects of delta 1-testolactone (Teslac) in vivo in rats and in vitro in human cultured fibroblasts, rat mammary carcinoma cells, and rat prostate cytosol.

The antiandrogenic properties of delta 1-testolactone (17 alpha-oxa-D-homo-1,4-androstane-3,17-dione; Teslac) were investigated in vivo and in vitro. Teslac (75 mg/day for 7 days) inhibited the rise in ventral prostate weight induced by testosterone (T) (P less than 0.001), dihydrotestosterone (DHT) (P less than 0.05), and a combination of T plus 17 beta-estradiol (E2) (P less than 0.01) in immature castrate rats. Similar effects were seen on the seminal vesicles after T and T plus E2 (P less than 0.001). Teslac also decreased prostate and seminal vesicle weights in intact immature rats. The effects of Teslac were dose and time dependent. Teslac did not change the concentration of serum T or DHT. However, Teslac inhibited DHT binding to the androgen receptor (Ki = 2.5 +/- 0.8 X 10(-7) M) in cytosol of the rat prostate. Teslac also inhibited DHT binding to the androgen receptor in cultured human prepuce fibroblasts and cultured rat mammary tumor cells (Ki = 1.9 +/- 0.3 X 10(-5) M). The results indicate that Teslac, in addition to its antiaromatase activity, is an antiandrogen by virtue of its interaction with the androgen receptor.

Androgen Antagonists↗
PubMed1982

Pituitary-testicular function in protein-deficient rats. Follicle-stimulating hormone hyperresponse to castration and supersensitivity of gonadotropin secretion to androgen negative feedback.

Previous studies have shown that weanling male rats fed a low protein diet ad libitum develop hypogonadotropic hypogonadism. Two unusual features of this state were 1) subnormal serum FSH in noncastrate rats but not in castrate rats, suggesting that FSH was being suppressed by a testicular factor, and 2) serum FSH increases after castration that were greater in protein-deficient rats than in controls. In the current study, protein-deficient rats showed FSH hyperresponse to castration, compared to either ad libitum or pair-fed controls, after periods of low protein feeding from 1-8 weeks and periods of castration from 1-8 weeks. FSH hyperresponse to castration was rapidly induced after the start of low protein feeding and was present whether castration was performed before or after low protein feeding was begun. In none of these circumstances did protein-deficient rats show LH hyperresponse to castration. Inhibin production of Sertoli cell cultures prepared from protein-deficient rats was less (P less than 0.02) than in ad libitum or pair-fed controls, suggesting that inhibin overproduction was not the cause of subnormal serum FSH in noncastrate protein-deficient rats. However, castrated rats fed a low protein diet were more sensitive to the negative feedback effects of testosterone on gonadotropin secretion than were ad libitum or pair-fed controls. We conclude that low serum gonadotropins in protein-deficient male rats may be related to hypersensitivity of these animals to the negative feedback effects of testosterone on gonadotropin secretion. In addition, FSH hyperresponse to castration, without corresponding LH hyperresponse, seems to be typical of protein deficiency, suggesting that protein deficiency may be a useful model for exploring the differential control of gonadotropin secretion.

Animals↗
PubMed1982

The effects of pyridoxine on pituitary hormone secretion in amenorrhea-galactorrhea syndromes.

Six patients with amenorrhea, five of whom had galactorrhea and elevated PRL levels, were evaluated on a metabolic ward. All had normal sella tomograms, normal thyroid functions, and routine laboratory evaluations. None of the patients had taken any medication in the previous 6 months. On alternate days, five patients received 500 microgram of TRH iv with the measurement of PRL, TSH, FSh, LH, and hGH; 500 mg L-dopa orally with the measurement of PRL, FSH, and LH; a bolus infusion of 300 mg pyridoxine (B6) with measurement of PRL, hGH, TSH, FSH, and LH; and 25 mg chlorpromazine (CPZ) im with the measurement of PRL, LH, and FSH. The patients were then discharged on 600 mg oral pyridoxine/day and were readmitted for a repeat of the complete protocol 21 days later. The patients were continued on 600 mg oral pyridoxine for 3-4 months with monthly evaluations of serum PRL, LH, and FSH levels. These evaluations continued for 3 months after discontinuing pyridoxine. There was no demonstrable change in serum PRL after acute or chronic B6 therapy, mor was there a significant change in the response of PRL to CPZ, L-dopa, or TRH. The mean basal PRL was 97.5 +/- 9.7 ng/ml and after 3-4 months of oral pyridoxine was 97.1 +/- 14.8. In addition, there was no significant change in LH or FSH levels in response to acute or chronic B6, TRH, L-dopa, or CPZ. Neither acute B6 infusion nor chronic B6 therapy had any effect on TSH or the TSH response to TRH. Finally, acute B6 infusion had no effect on hGH levels and there were no paradoxical hGH responses to TRH. Two patients began having regular menses while on chronic pyridoxine. Their hormonal responses did not differ from those of the group, however.

Adult↗
PubMed1982

Methotrexate levels in the interstitial space and seminiferous tubule of rat testis.

The ability of methotrexate (MTX) to pass from the blood into the interstitial space and seminiferous tubule of the rat was investigated using testicular micropuncture. MTX was administered to anesthetized adult Wister rats via a femoral vein cannula. Constant plasma levels of MTX were achieved by giving a priming dose followed by a constant infusion of 1, 10, or 100 mg/kg/hr with 6 to 27 rats studied at each dose. Blood (via a jugular vein cannula), testicular interstitial fluid, and seminiferous tubule fluid (via direct micropuncture) were periodically sampled during the 4 hr of drug infusion. Under steady-state conditions, when compared to corresponding plasma values, MTX levels were 2- to 4-fold lower in the testicular interstitial fluid and 18- to 50-fold lower in the seminiferous tubule. These results indicate that, in the rat, a significant blood-testis barrier to MTX exists at the tubular but probably not at the capillary-interstitial level. If these results can be extrapolated to humans, they do not provide a pharmacological explantation for the frequent occurrence of leukemic relapse in the interstitium of the testes in boys with acute lymphocytic leukemia.

Animals↗
PubMed1981

Cushing's disease presenting as amenorrhoea with hyperprolactinaemia: report of two cases.

Two patients with Cushing's disease first presented with amenorrhoea, hyperprolactinaemia, and normal tomograms of the sella turcica. Both women underwent trans-sphenoidal removal of a pituitary microadenoma resulting in a decreased serum prolactin concentration in both, and cessation of galactorrhoea and return of menses in one of them. One woman became ACTH deficient while the other has persistent Cushing's disease. A survey of the literature on Cushing's disease and prolactinomas shows the association to be uncommon. A likely mechanism is secretion of both hormones by the microadenomas. These two patients illustrate the need for screening other pituitary hormone function in patients with hyperprolactinaemia.

Adenoma↗
PubMed1981

Effects of delta 1-testolactone on the pituitary-testicular axis in oligospermic men.

Ten men with idiopathic oligospermia were treated with delta 1-testolactone (Teslac), a potent inhibitor of conversion of androgens to estrogens. Teslac therapy caused a fall in serum estradiol and estrone levels of 34% (P less than 0.01) and 41% (P less than 0.01), respectively, and a rise in serum testosterone and androstenedione of 47% (P less than 0.02) and 70% (P less than 0.01), respectively. The testosterone-estradiol ratio increased by 126% (23.5 +/- 2.5 x 10(-1) to 45.2 +/- 5.0 x 10(-1); P less than 0.01) and the androstenedione:estrone ratio increased 231% (4.7 +/- 0.6 x 10(-1) to 12.9 +/- 2.0 x 10(-1); P less than 0.01). Basal and LRH-stimulated serum gonadotropin levels were unaffected by these changes. Sperm density rose from 10.8 +/- 2.5 to 19.8 +/- 4.7 x 10(6)/ml (P less than 0.01) and total sperm count from 26.8 +/- 6.5 to 60.6 +/- 14.3 x 10(6) (P less than 0.001). There was no significant change in motility or semen volume. Three of the wives became pregnant. There were no adverse effects of Teslac administration. These data suggest that Teslac may be an effective treatment for men with idiopathic oligospermia. Though the data do not clearly elucidate the mechanism of this effect, they are consistent with the possibility that Teslac's lowering of estrogen levels may have been responsible for the improvement in spermatogenesis. The findings also suggest that moderate increases in the circulating androgen-estrogen ratio do not affect gonadotropin output in men.

Adult↗