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Biomedical subjects

A Miyake

Publications and source records attributed to A Miyake.

At least 307 records · Page 17Linked to original sources
PubMed1981

Thymosin stimulates secretion of luteinizing hormone-releasing factor.

Partially purified thymosin fraction 5 and one of its synthetic peptide components, thymosin beta 4, but not thymosin alpha 1, stimulated secretion of luteinizing hormone--releasing factor from superfused medial basal hypothalami from random cycling female rats. In addition, luteinizing hormone was released from pituitary glands superfused in sequence with hypothalami. No release of luteinizing hormone in response to thymosin was observed from pituitaries superfused alone. These data provide the first evidence of a direct effect of the endocrine thymus on the hypothalamus and suggest a potentially important role for thymic peptides in reproductive function.

Animals↗
PubMed1981

Proliferation and synapse formation of neuroblastoma glioma hybrid cells: effects of glia maturation factor.

Glia maturation factor (GMF), extracted from bovine brain, stimulated DNA synthesis and proliferation of glioma cells and hybrid cells derived from glioma and neuroblastoma cells (NG108-15), but had no effect on neuroblastoma cells. The synapse formation of NG108-15 cells with rat striated myotubes was lower in the presence of GMF than the control and also lower after treatment with prostaglandin E1 (PGE1) plus theophylline, indicating that GMF did not induce functional differentiation of NG108-15 cells. The results show that expression of mitogenic action for GMF in the hybrid cells is a property derived from the glioma parent, and that NG108-15 is therefore an excellent model for studying glial-neuronal interactions.

Animals↗
PubMed1981

Induction of ovulation in patients with normoprolactinemic amenorrhea by combined therapy with bromocriptine and clomiphene.

Bromocriptine is known to be effective in the treatment of women with hyperprolactinemic anovulation or amenorrhea-galactorrhea. A new schedule of combined treatment with bromocriptine and clomiphene citrate was applied to 23 patients with normoprolactinemic amenorrhea who failed to respond to clomiphene alone. Ovulation was restored by treatment in 14 of these patients (60.9%), resulting in pregnancy in 3 women. Treatment resulted in immediate suppression of serum prolactin levels and a gradual increase in serum luteinizing hormone levels and estradiol levels followed by a luteinizing hormone surge. The present results indicate that bromocriptine/clomiphene combination therapy is effective in the treatment of amenorrheic patients with normoprolactinemia who do not respond to clomiphene alone, and suggest that bromocriptine restores the responsiveness of the hypothalamic-pituitary-ovarian system to clomiphene.

Adult↗
PubMed1981

Restoration of the ovarian response to gonadotropins in patients after molar abortion.

The recovery of the ovarian response to gonadotropin stimulation after molar abortion was investigated in relation to the serum human chorionic gonadotropin (hCG) level. Thirteen women with an aborted mole were given 225 IU of human menopausal gonadotropin (hMG) per day for 3 consecutive days, and their serum levels of estradiol (E2) were determined by radioimmunoassay on days 1, 3, 5, and 7 after hMG administration. Women with serum hCG levels of less than 200 mIU/ml exhibited a normal increase in serum E2 levels in response to hMG, whereas women with serum hCG levels of 2000 mIU/ml or more did not show any change after hMG administration. These findings suggest that a serum level of hCG in excess of 2000 mIU/ml prevents normal ovarian E2 responsiveness to exogenous gonadotropin stimulation.

Abortion, Spontaneous↗
PubMed1980

Plasma luteinizing hormone-releasing hormone levels in normal women and patients with amenorrhea.

Plasma levels of immunoreactive luteinizing hormone-releasing hormone (LH-RH) in 89 women with normal menstrual cycles and 109 patients with amenorrhea of various etiologies were determined by specific radioimmunoassay after methanol extraction. The LH-RH levels in patients with hypergonadotropism and Sheehan's syndrome were more than 10 pg/ml, and were significantly higher than basal levels during normal cycles (4.2 +/- 0.3 pg/ml). The mean levels of LH-RH were low in all hypogonadotropic patients with amenorrhea, with the exception of a few patients who showed high LH-RH levels suggestive of a pituitary lesion. The LH-RH levels in patients with polycystic ovary syndrome were comparable with basal levels during normal cycles. It is concluded that, although there is considerable overlap of the plasma LH-RH levels in each group of amenorrheic patients divided according to gonadotropin level, determination of LH-RH levels may be useful for the differentiation of hypothalamic amenorrhea from pituitary amenorrhea.

Adolescent↗
PubMed1980

Luteinizing hormone-releasing hormone in cerebrospinal fluid of women.

The concentration of luteinizing hormone-releasing hormone (LH-RH) in both cerebrospinal fluid (CSF) and plasma in 36 women with various conditions were determined, and the correlation of LH-RH concentrations between plasma and CSF was studied. Paired samples of plasma and CSF were obtained just before operation and were extracted with methanol for LH-RH radioimmunoassay. LH and FSH were also measured by radioimmunoassay. The mean plasma LH-RH levels were 3.79 pg/ml in the follicular phase, 4.15 pg/ml in the luteal phase, 12.73 pg/ml in postmenopausal women and 2.31 pg/ml in pregnant women at term. No immunoreactive LH-RH in the CSF was found in 29 out of 36 subjects, and the remaining 7 subjects showed very low levels (less than 0.95 pg/ml). The LH-RH levels in the CSF of post-menopausal women were not higher their those in the remaining 3 groups, although their plasma levels of LH-RH were significantly (p less than 0.001) elevated. The mean plasma levels of LH and FSH in post-menopausal women were significantly higher than those in normal cyclic women and in pregnant women. The present results suggest that little or no LH-RH is present in the CSF, and it is not clear that there is any correlation between the LH-RH level of plasma and those of CSF.

Adult↗
PubMed1980

Changes in plasma LRH during the normal menstrual cycle in women.

The plasma concentration of immunoreactive LRH, LS, FSH, oestradiol and progesterone were measured dialy by a sensitive double antibody radioimmunoassay during 12 cycles of 8 normal cyclic women. The mean (+/- SE) immunoreactive LRH levels in the follicular and luteal phase except the immunoreactive LRH peaks during normal cycles were 4.18 +/- 0.38 pg/ml and 4.50 +/- 0.45 mg/ml, respectively. The immunoreactive LRH peaks were observed in 11 of 12 cycles, appearing on day -4 to -1 from the LH surge in 9 cycles and on day +1 and +2 in 2 cycles. The mean value of immunoreactice LRH peaks was 42.0 +/- 11.4 pg/ml with range of 12 to 154 pg/ml. The immunoreactive LRH peak lasted for one day in 10 cycles and for 4 days in one cycle. The immunoreactive LRH peaks in different cycles of the same women did not occur on the same day relative to the LH peak. The plasma immunoreactive LRH levels measured every 10 min for 40 min periods every day in normal cyclic women during the ovulatory phase showed slight, but not significant fluctuations. Plasma oestradiol levels began to increase on day -6, reaching a peak on day -1, and were followed by peaks of LH and FSH. These data indicate that increase in serum oestradiol was followed by release of LRH from the hypothalamus and pre-ovulatory discharge of gonadotrophins from the pituitary.

Adult↗
PubMed1979

Restoration of the gonadotrophin response to LH-RH and oestrogen administration in patients after molar abortion.

The relation of the hypothalamic-pituitary effect on gonadotrophin secretion and the concentration of serum hCG after molar abortion was investigated. Gonadotrophin release after a bolus injection of LH-RH or conjugated oestrogens was observed in 17 women until 5 months after molar abortion. Little if any response of gonadotrophin was observed at a hCG level of 100 mIU/ml or more, but the response of LH and FSH to LH-RH were restored to normal when the serum hCG level decreased to below 100 mIU/ml. A normal response of LH to conjugated oestrogens was observed at a serum hCG level of 20 mIU/ml or less. These findings suggest that a high level of hCG interferes with pituitary gonadotrophin secretion, that the threshold hCG levels for normal responses of gonadotrophins to LH-RH and oestrogen are 100 and 20 mIU/ml, respectively, and that secretion of gonadotrophins is restored even in the presence of a low hCG level.

Adult↗
PubMed1979

Restoration of oestrogen positive feedback effect on LH release by bromocriptine in hyperprolactinaemic patients with galactorrhoea-amenorrhoea.

Five mg of bromocriptine was administered for 3 weeks to 8 hyperprolactinaemic women with galactorrhoea-amernorrhoea, in whom the response of serum luteinizing hormone (LH) and follicle-stimulating hormone (FSH) to 100 micrograms of iv LH-releasing hormone (LH-RH) had been evaluated. Twenty mg of conjugated oestrogen (Premarin) was injected iv any day between the 10th and 12th day from the initiation of the treatment, and serum LH levels were serially determined for 120 h. Hyperresponse of LH with normal FSH response to LH-RH was observed in most patients. Bromocriptine treatment for 10 to 12 days significantly suppressed mean (+/- SE) serum prolactin (PRL) levels from 65.1 +/- 23.0 to 10.4 +/- 2.0 ng/ml, while LH (12.6 +/- 2.1 to 24.8 +/- 5.9 mIU/ml) and oestradiol (40.1 +/- 7.6 to 111.4 +/- 20.8 pg/ml) levels increased significantly. Patients on bromocriptine treatment showed LH release with a peak at 48 h after injection of Premarin. The mean per cent increases in LH were significantly higher than those in untreated patients with galactorrhoea-amenorrhoea between 32 and 96 h after the injection. The present results seem to suggest that the restoration of LH-releasing response to oestrogen following suppression of PRL by bromocriptine may play an important role in induction of ovulation in hyperprolactinaemic patients with galactorrhoea-amenorrhoea.

Adult↗
PubMed1979

Suppression of serum levels of luteinizing hormone by short- and long-loop negative feedback in ovariectomized women.

The suppressive effects of short- and long-loop negative feedback on serum levels of LH were assessed after administration of human chorionic gonadotrophin (HCG) and conjugated oestrogens. Fourteen ovariectomized women were injected intravenously with 5 mg conjugated oestrogens, eight of these patients were also given an intramuscular injection of 10,000 i.u. HCG 8 h later, while the other six patients were given a control injection of 0.9% saline. The serum levels of LH decreased by similar amounts in both groups of women. Thirteen other ovariectomized women were initially injected with 10,000 i.u. HCG, i.m., seven of these patients were also given an i.v. ijection of 5 mg conjugated oestrogens 8 h later, while the remaining six patients received a control injection of 0.9% saline. The results showed that conjugated estrogens could further supress the serum level of LH which had been reduced by prior HCG treatment. In six ovariectomized women who received i.m. saline injections at the start of the experiment and 8 h later, the serum levels of LH did not change significantly. It is concluded that the suppression of the serum concentrations of LH by long-loop negative feedback after administration of 5 mg conjugated oestrogens is greater than that by short-loop negative feedback after treatment with 10,000 i.u. HCG.

Adult↗