Search PubMed⌕ Search

Biomedical subjects

I Dyrenfurth

Publications and source records attributed to I Dyrenfurth.

At least 19 recordsLinked to original sources
PubMed1987

Sex hormones in lesbian and heterosexual women.

The authors measured plasma testosterone (T), androstenedione (A), and cortisol (C) levels in seven lesbian and seven heterosexual women matched for age and socioeconomic status. In addition, psychiatric symptoms, physical activity levels, depression, subjective sense of stress, and sexual behavior variables were assessed. There were no significant differences in sex hormone levels between the two groups of women, who were also comparable in psychiatric symptom levels, depression, and self-perceived stress. Lesbian women reported significantly more current physical activity relative to peers. Other than the sexual orientation difference which was a prerequisite for entry into the study, there were virtually no significant differences in sexual behavior although lesbian women tended to have achieved psychosexual milestones at a younger age. We were not able to corroborate the finding of Gartrell, Loriaux, and Chase (1977) that lesbian women have higher T levels, possibly due to the fact that the two groups were closely matched on several behavioral variables potentially affecting testosterone levels.

Adult↗
PubMed1987

Hypothalamic-pituitary-adrenal-cortical activity in anorexia nervosa and bulimia.

We studied hypothalamic-pituitary-adrenal-cortical (HPA) activity in nine underweight women with anorexia nervosa, 12 women of normal body weight with bulimia, and nine control subjects. The measures of HPA activity were the pattern of plasma cortisol secretion over 24 hr and the responses of plasma cortisol to dexamethasone suppression and to low dose ACTH stimulation. The patients with anorexia nervosa had significantly elevated 24 hr concentrations of plasma cortisol compared to the controls and showed significantly less cortisol suppression following dexamethasone. There was no difference between patients with anorexia nervosa and controls in the rise in plasma cortisol following ACTH. On most measures of HPA activity, the normal weight patients with bulimia were indistinguishable from the controls. These results suggest that HPA activity is normal in most patients of normal body weight with bulimia and that the psychological and behavioral disturbances common to both anorexia nervosa and bulimia are, in the absence of significant weight loss, insufficient to produce major alterations in HPA activity.

Adrenocorticotropic Hormone↗
PubMed1986

Clinical and biochemical features of depression in Parkinson's disease.

Among 49 consecutive patients with Parkinson's disease, 40% were depressed according to DSM-III; they had major depression or dysthymic disorder accompanied by sleep disturbance, fatigue, psychomotor retardation, loss of self-esteem, and excessive guilt. During a 10-day dopamine-free period, lumbar puncture was performed to measure the metabolites of dopamine, serotonin, and norepinephrine. Patients were given an overnight dexamethasone suppression test, and the effects of thyrotropin-releasing hormone and L-dopa on plasma growth hormone and prolactin were examined. Level of CSF 5-hydroxyindoleacetic acid was lowest in parkinsonian patients with major depression and was related to psychomotor retardation and loss of self-esteem.

Aged↗
PubMed1985

Effect of vitamin A deficiency upon gonadotropin response to gonadotropin-releasing hormone.

There is a monotypic change in basal serum gonadotropin levels following retinol treatment of chronically vitamin A-deficient (VAD) male rats. The present study was undertaken to investigate the hypothesis that the specific increase in serum follicle-stimulating hormone (FSH) represents a change in gonadotrope responsiveness to gonadotropin-releasing hormone (GnRH). To this end, a test dose of GnRH was given to VAD rats pre-, 5 days post-, and 10 days postreplacement of vitamin A (PVA). In VAD rats, basal serum FSH and luteinizing hormone (LH) levels were higher than those of controls. Increased LH/testosterone ratios, both in basal levels and in the secretory response to GnRH, suggested Leydig cell hyporesponsiveness in VAD animals. Both the FSH and LH responses to GnRH were maximal at 1 h, declining thereafter. Although the absolute increments in FSH and LH 1 h after GnRH in VAD rats were greater than in controls, the percent increase in FSH tended to be lower in VAD rats and to increase after vitamin A replacement. The specific enhancement of FSH release PVA became evident only when assessing total secretion of FSH and LH after GnRH. Luteinizing hormone response to GnRH increased PVA, but not significantly, while FSH secretion after GnRH increased both 5 and 10 days PVA, times during which basal FSH levels were also increasing. These changes in FSH secretion could not be attributed either to increases in endogenous GnRH or to changes in testosterone or estradiol levels. Basal serum androgen binding protein levels, elevated in VAD animals, did not respond to the acute increases in FSH after GnRH and remained high PVA, suggesting no acute change in Sertoli cell function. Thus, the PVA increase in FSH secretion unmasks a partial inhibition of the gonadotrope present in the retinol-deficient, retinoic acid-fed male rat.

Androgen-Binding Protein↗
PubMed1985

Effects of an antiprogesterone agent, RU-486, on the menstrual cycle of the rhesus monkey.

RU-486 (RU), a synthetic steroid with antiprogesterone receptor activity, was used to study the role of progesterone in the normal menstrual cycle of rhesus monkeys. The drug, at dosages of 2, 4, or 12 mg/kg, was administered as a single im injection during the luteal phase (days 5-8) in 16 experiments in 8 monkeys. RU had acute effects on the endometrium, as it induced menstruation within 3 days in spite of persistant progesterone elevations, thereby shortening the cycle length by about 5 days. Long term effects on menstrual cyclicity were also found with the higher RU doses. The intermenstrual interval after RU treatment increased from 31.8 +/- 2.4 (+/- SE) days after a 2 mg/kg dose of RU to 82.4 +/- 6.8 days after a 12 mg/kg dose of RU, with a control cycle length of 29.4 +/- 0.7 days. This prolonged interval was related to a delay in the completion of the follicular maturation process and, therefore, a delay in ovulation, as judged by estrogen and progesterone concentrations. Subsequent menstrual cycles were regular and ovulatory. Our results suggest that RU binds to the endometrial progesterone receptor, thereby inducing premature menstruation in the presence of elevated progesterone levels. RU also exerts long term effects on the hypothalamo-hypophyseal axis, since it significantly alters menstrual cyclicity.

Animals↗
PubMed1984

Pulsatile administration of gonadotropin-releasing hormone for induction of ovulation.

Chronic pulsatile administration of gonadotropin-releasing hormone (GnRH) was used to induce ovulation in 12 women with various ovulatory disorders. In the first group of eight patients with normal to low baseline levels of gonadotropin, seven responded favorably to the treatment. Follicular maturation was observed in 57% of the treated cycles, and normal ovulatory cycles were induced in 24% of the patients. Two patients became pregnant. The intravenous route of administration was more effective than the subcutaneous one, possibly in response to the GnRH profile after each pulse. (The amplitude of GnRH peaks after an intravenous pulse was four times that seen after a subcutaneous one.) In contrast, follicular maturation and ovulation could not be induced in four women of a second group of patients with normal baseline levels of follicle-stimulating hormone but with high and frequent pulses of luteinizing hormone. The conclusion reached was that pulsatile administration of GnRH can be a new therapeutic tool in the treatment of ovulatory disorders in women who have an insufficient endogenous release of GnRH.

Adult↗
PubMed1984

Menopausal hot flashes: thermoregulatory, cardiovascular, and circulating catecholamine and LH changes.

Thermoregulatory, cardiovascular and endocrine changes were simultaneously monitored in 11 post-menopausal women with frequent hot flashes (catecholamine and LH levels were measured in 5 and 6 subjects respectively). Plasma samples were obtained at 1- and 5-min intervals. Hot flashes were accompanied by abrupt increases in plasma epinephrine (about 150%) and concomitant decreases in norepinephrine (about 40%). Increased luteinizing hormone was associated with most hot flashes. A detailed sequence of hot flash-associated changes was established. An aura preceded the onset of the hot flash by several seconds. HR and FBF increased just before the onset of the flash and reached peak levels of 10-20 beats/min and 30-fold respectively. Coincident with vasodilation and sweating, finger temperature increased an average of 3.9 degrees C and esophageal temperature fell 0.2-0.6 degrees C. Flashes of both discrete and prolonged intervals were observed. Sensation was a reliable index of flash occurrence and intensity as measured physiologically. Our observations are consistent with the hypothesis that hot flashes are due to a change in the thermoregulatory set point. Furthermore, the changes in catecholamine levels are consistent with the cardiovascular changes accompanying hot flashes.

Body Temperature Regulation↗
PubMed1983

The effect of delta 1-testolactone on serum testosterone and estradiol in the adult male rat.

delta 1-Testolactone, an androgen derivative without intrinsic hormonal action, is known to block the aromatization of androgens to estrogens. This study was designed to assess its effect upon serum testosterone (T) and estradiol (E2) in the adult male rat. By itself, testolactone (TL) did not affect T/E2 levels in the dosages utilized. Daily injections of human chorionic gonadotropin (hCG) for 15 days caused a tenfold rise in serum T, although there was no increase in serum E2. When given along with hCG, TL did not alter the Leydig cell response. However, pretreatment of animals with TL increased the testicular response to hCG over that of saline-treated animals. Studies were also carried out to delineate the sources of estrogen in the adult male rat. These experiments demonstrate that (1) the majority of E2 is not testicular in origin but is derived from the adrenal; (2) the conversion of androgen precursors to E2 in the rat is not affected by TL; and (3) in spite of no demonstrable inhibition of E2 production, TL causes an increased Leydig cell responsiveness to hCG.

Animals↗
PubMed1983

Naloxone stimulation of luteinizing hormone secretion in the female monkey: influence of endocrine and experimental conditions.

It is known that opiate administration results in the inhibition of LH release. In this paper, we examine the role of endogenous opiates in the regulation of gonadotropin secretion during the menstrual cycle of the monkey. The objectives of these experiments were to determine the experimental and endocrine conditions that are conducive to increased gonadotropin secretion in response to endogenous opiate antagonism. In Exp 1, naloxone was administered during the luteal phase to three groups of monkeys under three different experimental conditions. When naloxone (2 mg, iv) was injected into conscious unrestrained or sedated animals, LH secretion increased 2- to 3-fold. In contrast, the same dose of naloxone failed to stimulate LH secretion in monkeys restrained in primate chairs. In Exp 2, the gonadotropin response to acute naloxone administration on each day of the menstrual cycle was determined. A significant increase in the serum LH concentration (greater than or equal to 20% within 40 min of injection) was observed after naloxone administration in 60% of the trials conducted during the luteal phase. Significant increases occurred in only 13% of the saline-treated control trials during this stage of the menstrual cycle. Mean LH levels increased from 14.4 +/- 1.3 to 31.2 +/- 4.3 ng/ml after naloxone injection. In contrast, naloxone had no effect on LH secretion during the follicular phase. Although small LH increments were noted after naloxone injection in 40 +/- 8% of the trials, neither the frequency nor the amplitude of these increases was different from that in follicular phase controls. We conclude from these results that the ability of naloxone to stimulate LH secretion is limited to the luteal phase. Previous findings from our laboratory indicate that hypothalamic beta-endorphin activity, as reflected by its concentration in hypophyseal portal blood, is increased by ovarian steroids and that its greatest activity occurs during the luteal phase. Since the response of LH to naloxone administration was limited to the luteal phase, we believe that these results support the conclusion that hypothalamic beta-endorphin is a physiological modulator of LH secretion in the monkey.

Animals↗
PubMed1983

Photoperiod and ovulatory menstrual cycles in female macaque monkeys.

Macaques (Macaca mulatta and M. assamensis) which had been maintained on a 12L :12D light cycle for the previous 4 years and had 25-35-day menstrual cycles were randomly assigned to two groups. Those in Group 1 were kept in 12L :12D for 13 months. Those in Group 2 were subjected to three successive 5-month periods of 20L :4D, 4L :20D and 20L :4D. There were no significant differences between the two groups in the frequency, duration and percentage of ovulatory menstrual cycles, suggesting that photoperiod is not the sole regulator of seasonal breeding in these animals.

Animals↗
PubMed1980

The use of human menopausal and chorionic gonadotropins for induction of ovulation. Sixteen years' experience at the Sloane Hospital for Women.

Gonadotropin therapy for anovulation is highly successful: 58.6% of treated patients conceive. Better results are achieved in patients with galactorrhea-amenorrhea (77.1%) and hypogonadotropic hypogonadism (63.3%) than in patients with normal gonadotropin levels (45.4%). The spontaneous abortion rate (27.5%) is somewhat higher than that in spontaneous pregnancies. The multiple pregnancy rate is 31% and was slightly lower in cycles with preovulatory estrogen levels in the physiologic range. In patients treated with human menopausal and chorionic gonadotropins for 7 to 9 days per cycle, the multiple pregnancy rate is considerably less (12.9%) than in patients with longer treatment. The efficacy of treatment does not diminish with repeat-treatment cycles.

Amenorrhea↗
PubMed1980

Amniotic fluid fluorescence polarization value as a predictor of respiratory distress syndrome.

Fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene in amniotic fluid lipid aggregates was measured to determine the ability of this technique to prospectively predict respiratory distress syndrome. Prior retrospective studies have shown that an FP value of less than or equal to 0.336 correlated best with a lecithin to sphingomyelin ratio of greater than 2.0. Fluorescence polarization values of amniotic fluid samples obtained within 48 hours of birth from 161 pregnancies were correlated with neonatal outcome. Samples from 149 pregnancies had FP values of less than or equal to 0.336 and samples from 12 pregnancies had FP values of greater than or equal to 0.336. No infants delivered from the former group developed RDS and eight of 12 infants from the latter group developed RDS (P less than 0.001). In the entire population the test had a sensitivity of 100% and a specificity of 97%. When 37 infants with birth weights less than 2,500 gm were studied, the FP value remained a highly reliable predictor of the infant at risk for developing RDS (P less than 0.001). In this subset the test had a sensitivity of 100% and a specificity of 90%. L-S ratios were performed on 96 samples and the results correlated well with FP values (P less than 0.001). We conclude that the amniotic fluid FP value is a reliable index of fetal lung maturity and the risk for developing RDS. The FP value also has specific technical and diagnostic advantages over the L-S ratio.

Amniotic Fluid↗
PubMed1980

Section of the pituitary stalk in the rhesus monkey. I. Endocrine studies.

The effects of pituitary stalk section on anterior pituitary secretion were studied in 20 female rhesus monkeys. Vascular connections between the hypothalamus and the pituitary gland were permanently interrupted in all but 4 animals. Prolactin levels rose rapidly and remained significantly elevated in all effectively stalk-sectioned animals for as long as the observation period (up to 3 years). Only smaller and transient elevations of prolactin were seen in the animals in which revascularization of the anterior pituitary gland had occurred. Growth hormone and cortisol were significantly decreased after stalk section, and were not released by insulin. Radioimmunoassayable luteinizing hormone (LH) levels decreased following surgery and, by bioassay, LH became undetectable within 5 weeks after stalk section, indicating that gonadotropin-releasing hormone is essential for the viability of the gonadotrope. The results indicate that plasma prolactin concentrations can be used to monitor completeness of pituitary gland isolation from direct hypothalamic influence. Stalk-sectioned monkeys provide good models to study direct pituitary effects of various hormones or drugs.

Animals↗