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Biomedical subjects

L Tyrey

Publications and source records attributed to L Tyrey.

At least 55 records · Page 3Linked to original sources
PubMed1977

Luteinizing hormone-releasing hormone in the human fetal brain.

Hypothalamic and other brain tissues were obtained after death from human fetuses aborted by hysterectomy at various conceptional ages. Immunoreactive luteinizing hormone-releasing hormone (LHRH) activity in tissue extracts was determined by a double-antibody radioimmunoassay method. Fetal hypothalamic and cortical tissue at 5 weeks after conception showed no assayable LHRH activity. At 6 weeks, immunoreactive LHRH was detectable in extracts of both the hypothalamus and the cortex, and levels appeared to fluctuate with a trend to increase until the 20th week. Two of four fetuses at 13 and 14 weeks' conceptional age had significantly higher LHRH activity in the thalamus than in the rest of the central nervous system. After 16 weeks, LHRH activity was detected in the hypothalamus, thalamus, cerebrum, and cerebellum in decreasing concentrations, respectively. As the age of the fetus progressed from 16 to 20 weeks, the LHRH concentration in the hypothalamus increased significantly, from 1.2 pg/mg to 29.3 pg/mg of wet tissue. LHRH concentrations in specimens of comparable conceptional age that could not be promptly dissected were lower than in those dissected within 30 minutes after the ligation of uterine arteries.

Brain↗
PubMed1976

Vasomotor symptoms, serum estrogens, and gonadotropin levels in surgical menopause.

Hormonal parameters of young women who developed vasomotor symptoms in the immediate postoperative period following castration are compared to those who remained asymptomatic. Only 37.5 per cent of 16 premenopausal women developed "hot flushes" after operation. Perimenopausal women with vasomotor symptoms and elevated follicle-stimulating hormone levels demonstrated normal luteinizing hormone and estrogen values preoperatively. There were no statistically significant differences in total serum estrogen, follicle-stimulating hormone, or luteinizing hormone concentrations between the group of patients with symptoms and the group withoyt symptoms. The results of the study indicate that rising gonadotropin or declining estrogen values appear to have no direct correlation to the onset of vasomotor symptoms in the immediate postoperative period. Thus, the precise etiology of the "hot flush" remains to be elucidated.

Adult↗
PubMed1976

The HCG-beta-subunit radioimmunoassay: potential error in HCG measurement related to choice of labeled antigen.

Antiserum generated against the hormone-specific beta-subunit of hCG uas used with different labeled antigens to measure circulating hCG in patients having trophoblastic disease. When 125 I-hCGbeta served as the labeled antigen, a small number of patient sera failed to show parallelism with the second IS-hCG reference and erroneous estimates of hormone concentrations were obtained. Replacement of the 125I-hCGbeta with labeled hCG corrected the nonparallelism exhibited by these samples. Inhibition curves obtained with purified hCG and hCGbeta suggested that both the nonparallelism and its correction with the change in labeled antigen would be consistent with the possibility that this assay aberration may result from the presence of free hCGbeta in these sera.

Antigens↗
PubMed1976

Comparative effectiveness of preoptic and tuberal stimulation for luteinizing hormone release and ovulation in two strains of rats.

Proestrous rats under pentobarbital anesthesia during the 'critical period' were electrically stimulated in either the medial preoptic area (mPOA) or the anterior basal tuber. In Osborne-Mendel (O-M) and Charles River CD rats, comparisons were made of the ovulatory responses to trains of matched biphasic pulse pairs of different microamperage, 30 sec on and 30 sec off for 45 min. In CD rats, comparisons were made of the relative efficiencies of stimulation through a coaxial platinum electrode near the midline and a pair of platinum electrodes spaced bilaterally 2 mm apart across either the mPOA or the tuber. Other comparisons, with either type of electrode in the basal tuber, were made between 4-day and 5-day cyclic CD rats with respect both to the ovulatory responses and to the serum concentrations of LH 90 min after the start of the 45-min stimulus. In both O-M and CD rats, tuberal stimulation was more effective for ovulation than mPOA stimulation. CD rats were much less responsive to mPOA stimulation (spaced electrodes) than O-M rats, but the responses of both strains to tuberal stimulation were essentially alike. In 4-day cyclic CD rats, the ovulatory responses to mPOA stimulation with the coaxial electrode were much superior to those from spaced-electrode stimulation. In contrast, tuberal stimulation with either type of electrode gave equivalent ovulation frequencies and equivalent tubal ovum numbers in both 4-day and 5-day cyclic rats. However, the serum LH concentrations disclosed somewhat better responses to stimulation with the coaxial electrode (coaxial/spaced=1.57). The advantage of stimulation with the coaxial electrode may be due to high current density or, at least in part, to its more medial location. The results are compatible with the concept of preoptic-tuberal neuronal system, diffuse rostrally and convergent upon the medial basal tuber, controlling the ovulatory surge of LH.

Animals↗
PubMed1976

Changes in (125I) labeled human chorionic gonadotropin (hCG) binding to porcine granulosa cells during follicle development and cell culture.

The specific binding of (125I)iodo human chorionic gonadotropin to porcine granulosa cells isolated at two stages of follicle maturation was quantitated immediately after harvest and following 6-7 days of culture. Both porcine LH (pLH, LER 786-3) and hCG inhibited (125I)iodo hCG binding, while pFSH (ler-1132) did not compete for hCG with granulosa cells for 24-48 hours at 37 C did not alter its subsequent ability to bind to fresh cells. The binding of (125I)iodo hCG was a rapid process which was not readily reversible. Scatchard analysis of the equilibrium binding data resulted in linear plots showing the hCG binding capacity of highly differentiated (HD) cells, harvested from large preovulatory follicles, to be significantly greater than that of moderately differentiated (MD) cells isolated from smaller luteal phase follicles, both before (794 vs 93 pmoles/g; P less than 0.001) and after (157 vs 5 pmoles/g; P less than 0.001) culture. A decline in binding capacity occurred in both cell groups during culture and was associated with a significant decrease in progestin production. In contrast, the hCG binding affinity of the granulosa cell was equivalent at both stages of follicle development and remained unchanged after 6 days of culture (mean apparent Kd = 2.9 x 10-10M; n=27. These data indicate that porcine granulosa cells contain a homogeneous class of LH receptors whose number, but not affinity, increases during follicle maturation in vivo. The loss of receptors in vitro suggests the absence of some factors(s), as yet unidentified, critical to the maintenance and development of the receptor population.

Animals↗
PubMed1976

Luteinizing hormone requirements for ovulation in the pentobarbital-treated proestrous rat.

The LH requirements for ovulation in the pentobarbital-blocked proestrous CD rat have been studied by increasing serum gonadotropin levels through electrical stimulation of the brain and subsequently comparing the effects of timed hypophysectomy on ovulation and serum LH concentrations. The arcuate nucleus (ARC) or the medial preoptic area (POA) was stimulated unilaterally for 45 min with matched pairs of biphasic rectangular pulses through a coaxial platinum electrode. Serum LH was significantly elevated above basal values at the end of stimulation, but not in sham-stimulated controls. The results of both hormone measurement and hypophysectomy showed that the pituitary continued to release LH after extrinsic stimulation of the hypothalamus had ceased. Animals did not ovulate if they had been hypophysectomized at the end of the 45 min stimulation whereas nearly all ovulated if hypophysectomy was delayed for an additional 20 min. Some evidence suggested that the pituitary could be removed earlier without affecting ovulation if the rate of LH release was increased. The minimum peak LH concentration measured in rats that subsequently ovulated fully was 187 ng/ml, substantially lower than concentrations ordinarily attained in the spontaneous proestrous surge. When serum LH was insufficiently high to cause follicle rupture, there was nevertheless the resumption of meiosis and luteinization of the large ovarian follicles. Attempts were made to restore ovulability in animals presumed to have released a subovulatory quota of gonadotropin. Ovulation was obtained when such animals, prepared by hypophysectomy after the 45 min stimulation, had been bilaterally nephrectomized prior to stimulation. However, multiple injections of progesterone after hypophysectomy were without effect. The results are discussed in relation to variables that affect minimum requirements of LH for ovulation.

Animals↗
PubMed1976

Gonadotropin release in patients with androgen insensitivity. Testicular feminization syndrome.

Two siblings are presented, both with classic androgen-insensitivity syndrome (AIS). Endocrine testing was carried out and then gonadectomy was performed. Studies in these patients with AIS revealed low control serum FSH. In these patients serum FSH was not significantly suppressed by intravenous estrogen nor adequately stimulated by FSH-LH-releasing hormone but rose normally after castration. The various studies are interpreted in the light of the known kinetics of pituitary gonadotorpins and their modulation by gonadal steroids. A third sibling is also presented.

Adult↗
PubMed1975

Serum prolactin and LH in early phases of delayed versus direct pseudopregnancy in the rat.

Delayed or direct pseudopregnancies were induced by electrical stimulation of the cervix at 1400 h on diestrus day 2 (D-2) or on estrus, respectively. Blood samples for measurement of prolactin and LH by radioimmunoassay were collected by rapid decapitation at 5, 15, 30, 45 or 60 min after cervical stimulation or thereafter at 3-h intervals throughout the first 6 days of leukocytic vaginal smears of pseudopregnancy (PSP L-1 to L-6). For comparison, untreated animals were decapitated at the same 3-h intervals throughout the 4-day cycle. Serum LH concentrations in all the experimental animals did not vary from those measured in the cyclic controls. Compared with the normal cycle, prolactin (PRL) levels were not different until 10 h after cervical stimulation during estrus. After stimulation on D-2, PRL secretion did not differ from that in the normal cycle until approximately 37 h later, when there was a short rise following the usual proestrus surge. In both direct and delayed pseudopregnancy, twice-daily PRL surges appeared on L-1 and, except for a missing nocturnal surge on L-2 in delayed PSP, continued regularly through L-6. The absence of any immediate increase of PRL following the D-2 stimulus strongly supports the view that information from the stimulus is retained in the central nervous system to be expressed later after a set of new, competent corpora lutea has been formed.

Animals↗
PubMed1975

Hydatidiform mole: diagnosis, management, and long-term followup of 347 patients.

This report concerns 347 patients with primary hydatidiform moles studied during the first 6 years (1966-1972) of operation of the Southeastern Regional Trophoblastic Disease Center. Aside from a decreased incidence, molar pregnancy in the United States follows a pattern similar to that elsewhere in the world. Abnormal bleeding is the key to early diagnosis, and the frequent use of sensitive HCG assays is the key to proper followup. Twenty percent of patients with hydatidiform moles can be expected to develop subsequent malignant sequelae. Bilateral ovarian enlargement and/or a large-for-dates- uterus should alert the physician to a greater potential for this outcome. Spontaneous elimination of HCG from the circulation following moler pregnancy, as indicated by sensitive assay, would predict a benign postmolar course; no patient in the current series who once achieved undetectable levels of HCG developed malignant trophoblastic disease.

Abortion, Induced↗