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Biomedical subjects

A Y Silverman

Publications and source records attributed to A Y Silverman.

18 recordsLinked to original sources
PubMed2002

Female sex selection using clomiphene citrate and albumin separation of human sperm.

BACKGROUND: This study was undertaken to assess whether the use of clomiphene citrate in conjunction with albumin-separated sperm would alter the sex ratio (expressed as the proportion of males) towards females and, if so, whether this skewing was due solely to the induction of ovulation. METHODS: The sex ratios of 184 single and 42 twin births at five assisted reproduction biology clinics were determined. The normal approximation to the binomial distribution was used to determine significant differences between these sex ratios and the established sex ratios for single, twin and combined (single and twin) non- and ovulation-induced births. RESULTS: The non-ovulation-induced sex ratios for singletons (51.4%) and twins (50.2%) were greater than the treatment singleton (27.7%; P < 0.001) and twin (33.3%; P < 0.01) sex ratios respectively. Correspondingly, the non-induced sex ratio for combined births (51.4%) was greater than the treatment sex ratio (28.8%; P < 0.001). The previously established induced singleton and twin sex ratios (48.1%) were lower than the non-induced sex ratio (51.4%), but higher than the treatment singleton (27.7%; P < 0.001) or twin (33.3%; P < 0.03) sex ratios. The ovulation-induced combined ratio (48.1%) was less than the non-induced combined (51.4%) sex ratio, although greater than the treatment combined sex ratio (28.8%; P < 0.001). CONCLUSION: Clomiphene citrate in conjunction with albumin-separated sperm decreased the sex ratio; a reduction that was not exclusively due to induction of ovulation.

Cell Separation↗
PubMed1983

Topographical distribution of the gonadotrophs, mammotrophs, somatotrophs and thyrotrophs in the pituitary gland of the baboon (Papio cynocephalus).

The identification and regionalization of four pituitary parenchymal cell types, gonadotrophs, mammotrophs, somatotrophs and thyrotrophs, were studied in the baboon (Papio cynocephalus) hypophysis using immunocytochemistry. The gonadotrophs were homogeneously distributed throughout the entire pars distalis. Both mammotrophs and somatotrophs predominate at the superior and inferior poles of the organ. The medial and anteromedial regions are populated by mammotrophs and thyrotrophs, while the lateral and posterior portions of the pars distalis contain large numbers of somatotrophs.

Animals↗
PubMed1983

Assay for characterization of human follicular oocyte maturation inhibitor using Xenopus oocytes.

Human follicular fluid from healthy mature Graafian follicles and from pathologic ovarian cyst fluid was found to be inhibitory to progesterone-induced meiotic maturation of oocytes from the South African clawed toad, Xenopus laevis. Human follicular fluid but not human serum, collected from the same individuals, demonstrated a linear dose-response inhibition on the maturation of oocytes in the Xenopus assay system. These findings indicate that the human follicular and cyst fluids contain oocyte maturation inhibitor (OMI). This human OMI was inactivated when subjected to a boiling water bath for 2 min. The OMI action was shown to be reversible in its inhibitory action. The fact that OMI can act directly on the oocyte was demonstrated by its inhibitory action on maturation in defolliculated oocytes. The findings demonstrate that the inhibitory action of human OMI is not species-specific. Xenopus oocytes provide a simple, readily available, year-round bioassay material for testing follicular oocyte maturation inhibitor.

Animals↗
PubMed1983

Interactions of delta 9-tetrahydrocannabinol (THC) with hypothalamic neurotransmitters controlling luteinizing hormone and prolactin release.

The effects of delta 9-tetrahydrocannabinol (THC) on hypothalamic norepinephrine (NE) and dopamine (DA) turnover and hypothalamic serotonin (5-HT), 5-hydroxyindole acetic acid (5-HIAA) and LHRH content preceding and during a progesterone- (P) induced LH and prolactin (PRL) surge were investigated in ovariectomized estrogen-primed rats. THC had no effect on basal LH levels, but it inhibited basal PRL levels and blocked the surges of both LH and PRL. The turnover of NE, as estimated by measuring NE depletion after inhibition of tyrosine hydroxylase with alpha-methyl tyrosine (250 mg/kg), in both the anterior (AH) and medial basal hypothalamus (MBH) was significantly inhibited by THC. THC did not significantly affect AH or MBH DA or 5-HT content nor MBH-DA-turnover. Hypothalamic LHRH levels were significantly elevated 4 h after THC administration as compared to the vehicle-injected controls, but pituitary response to exogenous LHRH was not affected. These data suggest that THC inhibits the steroid-induced positive feedback release of LH by reducing NE metabolism and the release of hypothalamic LHRH. Although the mechanism for the inhibition of PRL release by THC is not clear from these experiments, it does not appear that alterations in DA turnover are a contributing factor.

Animals↗
PubMed1982

Response of rhesus monkey lymphocytes to short-term administration of THC.

Four Rhesus monkeys were subjected to daily administration of 2.5 mg of tetrahydrocannabinol (THC)/kg body wt, after establishing the norms for complete blood count, T- and B-cell concentrations, and the dose response of thymidine incorporation after PHA stimulation. THC was administered daily for 3 weeks, the treatment was stopped, and then the animals were allowed to recover for 4 weeks. Cellular responses, incorporation studies and fibrinogen levels were determined during the treatment and recovery phases. Compared to 4 vehicle-treated animals, the THC-treated animals experienced significant augmentation of both their total white cell and their neutrophil counts during the recovery phase which returned to normal levels during the recovery phase. There was no alteration in total lymphocyte count or T- or B-cell concentrations. Fibrinogen levels of the THC-treated animals during the treatment phase were also elevated compared to controls, and the levels diminished to the same values as the vehicle-treated animals during recovery phase. Possible mechanisms for the response of Rhesus monkeys to short-term administration of THC are discussed.

Animals↗
PubMed1982

A quantitative difference between immunologically and biologically active prolactin in hypothyroid patients.

Under certain conditions, the pituitary may secrete PRL species displaying diverse immunological and biological activities. To study this phenomenon further, we compared PRL determined by RIA and radioreceptor assay (RRA) in 25 hypothyroid patients (TSH, greater than 10 microU/ml) and in 49 endocrinologically normal patients. In the normal women, the ratio of the PRL mean determined by RRA (67.3 ng/ml) to that determined by RIA (13.5 ng/ml) was 4.99 +/- 0.435. By contrast, in hypothyroid patients, PRL determined by RRA was significantly lower than the value determined by RIA for each patient, and the ratio of means (RRA to RIA) was 0.782 +/- 0.067. The mean PRL determined by RRA (52.2 ng/ml) was not significantly different from the mean of control patients (P greater than 0.5). PRL determined by RIA was elevated in all hypothyroid patients (range, 24-237 ng/ml), and the mean (by RIA) (64.1 ng/ml) was significantly elevated above the mean PRL (by RIA) of controls (P less than 0.000001). Thus, in the chronically hypothyroid patients, PRL is characterized as possessing normal receptor-binding activity and augmented immunological activity.

Adult↗
PubMed1981

Human chorionic gonadotropin blocks the estrogen-induced luteinizing hormone release in long-term castrated rhesus monkeys: evidence for an ultrashort-loop negative feedback.

We studied the effects of human chorionic gonadotropin (hCG) administration on the biphasic response of luteinizing hormone (LH) to estrogen challenge in long-term castrated, female rhesus monkeys. Estradiol benzoate (EB), 400 micrograms, was administered to all animals at time zero; hCG, 2000 IU, was administered either concomitantly or 12 hours after EB. Blood samples were obtained every 6 hours for 58 hours, and then at 72 and 82 hours. Control animals received EB alone. Serum LH and beta hCG were determined by radioimmunoassay. Control animals showed a typical biphasic response to EB: an initial decrease in LH levels, 50% to 70% of baseline, from +6 hours until +30 hours; then a large increase, 150% to 190% of baseline, at +48 hours. Animals treated with hCG at time zero showed an initial decrease in LH, 40% to 70% of baseline, but LH returned to basal levels at +42 hours. Animals treated with hCG 12 hours after EB showed an initial decrease in LH, 45% to 55% of baseline, but LH returned to basal levels at +36 hours. These results suggest that an LH ultrashort-loop negative feedback may exist in the nonhuman primate.

Animals↗
PubMed1981

Glucocorticoid suppression of pituitary prolactin release in the nonhuman primate.

The administration of 8 mg dexamethasone daily for 8 days significantly lowered basal and TRH-stimulated PRL levels in ovariectomized rhesus monkeys. A single acute injection of dexamethasone attenuated the total amount of PRL released after TRH stimulation, although basal and peak PRL levels were not significantly different from those found in controls. In an attempt to determine the site of action of glucocorticoids on PRL secretion, baboon pituitaries were incubated with cortisol. Cortisol at a concentration of 3 x 10(-5) M significantly inhibited PRL secretion in vitro, while a concentration of 3 x 10(-4) M was needed to block TRH-stimulated prolactin release. In conclusion, glucocorticoids can suppress pituitary PRL secretion by a direct action on the pituitary gland, although a hypothalamic site of action may also be involved.

Animals↗
PubMed1981

Interactions of cocaine and delta 9-tetrahydrocannabinol with the hypothalamic-hypophysial axis of the female rat.

The acute effects of cocaine and/or delta 9-tetrahydrocannabinol (THC) were studied in ovariectomized female rats. Intermediate doses of cocaine (10 or 20 mg/kg) caused an increase in serum luteinizing hormone (LH) and a decrease in serum prolactin levels, whereas a higher dose (40 mg/kg) caused a decrease in serum LH. THC (10 mg/kg) attenuated serum LH and prolactin levels. The THC effect on LH was blocked by cocaine. Neither drug alone or in combination affected serum follicle-stimulating hormone levels. The cocaine-induced changes in LH levels were closely paralleled by changes in hypothalamic norepinephrine content, suggesting a neurochemical basis for cocaine's action on LH release.

Animals↗
PubMed1979

Comparison of glucocorticoid conjugates with other indexes of fetal maturation.

Controversy exists as to whether cortisol acts physiologically to accelerate human fetal lung maturation. Recent data from this laboratory showed that cortisol and corticosterone conjugates (GCS) rise fivefold in anmiotic fluid late in pregnancy and correlate well with the palmitic/stearic (P/S) ratio (r = 0.79). In this study GCS was compared with various tests of fetal maturation. In a series of 38 cases compared with the lecithin/sphingomyelin (L/S) ratio, the GCS and palmitic acid had the highest concurrence (84% agreement), followed by the "shake" test (82%), cortisol (74%), cytology (64%), gestational age determined by ultrasound (63%), and creatinine (47%). The GCS correlate better than cortisol itself, probably because cortisol in amniotic fluid is derived from the chorionic membrane as well as from fetal urine. These observations provide convincing evidence of a physiologic link between fetal lung maturation and alteration in fetal steroid production.

Amniotic Fluid↗
PubMed1975

Distribution of murine type B and type C viral nucleic acid sequences in template active and template inactive chromatin.

Template active chromatin and template inactive chromatin have been fractionated from mouse cells infected with the Moloney strain of murine leukemia virus. In vivo the cells produce abundant Rna homologous to Moloney leukemia virus, but do not produce either globin mRNA or RNA homologous to type B mouse mammary tumor virus. The DNA extracted from the template active chromatin or template inactive chromatin contained equal amounts of sequences homologous to Moloney type C virus, to type B virus, or to globin mRNA. The results are discussed with regard to the in vivo structure of chromatin and the difficulties in fractionating chromatin in vitro.

Animals↗
PubMedDate not supplied

Human chorionic gonadotropin and steroid concentrations in human follicular fluid in relation to follicle size and oocyte maturity in stimulated ovarian cycles.

The concentrations in follicular fluid (FF) of beta hCG, progesterone (P), estradiol (E2), androstenedione (A) and testosterone (T) by RIA were determined, in order to study the follicular micro-environment in stimulated cycles. Patients received either clomiphene with hMG plus hCG or hMG plus hCG. With increasing volume of FF (obtained at laparoscopy), P significantly increased (p less than 0.04) and hCG (p less than 0.0004) and T (p less than 0.05) significantly decreased with a borderline decrease in A (p less than 0.07). Progesterone also increased with advancing oocyte maturity. Beta-hCG and P were positively correlated with E2 and negatively correlated with A levels. It is suggested that FF hCG and progesterone levels may be markers of follicular development in stimulated cycles.

Androstenedione↗