C. C. TSAI

Nagoya University

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S. S. C. YEN

University of California, San Diego

Frederick Naftolin

New York University

Patricio A. Vela

Georgia Institute of Technology

L. N. Ajabor

University of Benin

Grant W. Vandenberg

Université Laval

Robert W. Rebar

Western Michigan University

Shao‐Hua Xie

Karolinska University Hospital

Tatsushi Yokoyama

Kyoto University

Akihiro Yamanaka

Chinese Institute for Brain Research

Deborah F. Perlman

Providence College

Cooperative Institutions

University of California, San Diego

Nagoya University

Japan Science and Technology Agency

Science and Technology Corporation (United States)

Centre for Research in Engineering Surface Technology

Centre de Recherche en Économie et Statistique

Scripps Health

Scripps Clinic

Salk Institute for Biological Studies

Columbia University

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The Biphasic Pattern in the Feedback Action of Ethinyl Estradiol on the Release of Pituitary FSH and LH*

The Journal of Clinical Endocrinology & Metabolism (1971)

S. S. C. YEN C. C. TSAI

Assessment of sequential changes of circulating LH and FSH in response to ethinyl estradiol (EE) treatment was made in 7 postmenopausal women. During a relatively short period of treatment (5–8 days) EE (400 μg/day) initially exerts a negative feedback action which was greater for FSH (36% of control) than for LH (49% of control). This was followed by the occurrence on the 3rd and 4th day of an augmented phase of gonadotropin release which consisted of either acute surges or oscillations. This positive feedback action of EE is quantitatively much greater for LH than for FSH. These results indicate that EE exerts a biphasic action (suppression followed by augmentation) on the gonadotropin-releasing mechanism and that a differential estrogen feedback control between FSH and LH exists.

Gonadotropin

Feedback Control

Mechanism of Action

10.1210/jcem-33-6-882

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Citations (98)

Gestational diabetogenesis: Quantitative analyses of glucose-insulin interrelationship between normal pregnancy and pregnancy with gestational diabetes

American Journal of Obstetrics and Gynecology (1971)

S. S. C. YEN C. C. TSAI Patricio A. Vela

Post partum

10.1016/0002-9378(71)90490-x

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Citations (58)

Gonadotropin Dynamics in Patients with Gonadal Dysgenesis: A Model for the Study of Gonadotropin Regulation

The Journal of Clinical Endocrinology & Metabolism (1972)

S. S. C. YEN C. C. TSAI Grant W. Vandenberg Robert W. Rebar

In 19 patients with gonadal dysgenesis, 12–35 yr of age, a disproportionally greater elevation of serum FSH (10 times) than LH (2–3 times) was found when compared with the values observed in premenopausal women. The mean serum LH concentration, but not mean serum FSH concentration, was significantly lower than those found in postmenopausal women. The elevated levels of serum LH and FSH in these patients are maintained by periodic pulsatile pituitary discharges with an average frequency of 90 min. Coincidental pulses of LH and FSH of comparable magnitude are discernible, but obvious dissimilarities in the pattern are apparent. E2 infusion (50 μg/hr × 4 hr) abolished the pulsatile nature of LH release and to a lesser degree FSH release which resulted in a rapid reduction in circulating gonadotropin concentrations. Despite the rapid disappearance of circulating E2 following the infusion, the suppression was sustained for an average of 6 hr. The pattern of recovery was composed of an abrupt resumption of pulsatile discharges of larger magnitude than those observed during control periods. This was more apparent for LH than for FSH which resulted in a reduction of FSH/LH ratio. During a period of sustained suppression by ethinyl estradiol, a concomitant release of LH and FSH in response to im progesterone and estradiol benzoate administration was observed. These data indicate that the unrestrained hypothalamicpituitary system in patients with gonadal dysgenesis is responsive to both negative and positive feedback action of estradiol and that estradiol is a major gonadal steroid in the regulation of tonic gonadotropin secretion via modulation of the amplitude of the pulsatile discharges.

Gonadotropin

Pulsatile flow

10.1210/jcem-35-6-897

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Citations (120)

The effect of ovariectomy on gonadotropin release

Journal of Clinical Investigation (1971)

S. S. C. YEN C. C. TSAI

The sequential changes in the concentration and pattern of circulating luteinizing hormone (LH) and follicle-stimulating hormone (FSH)(1) following bilateral ovariectomy were determined in 10 premenopausal women. The initial (1st wk) and delayed (3 wk) secretory responses of serum LH and FSH as related to the phases of the menstrual cycle were examined. Ovariectomy during follicular phase was accompanied by a prompt and much greater rise in both LH and FSH during the 1st wk. This rapid rise was followed by a transient decline between the 7th and 10th day which resulted in a biphasic pattern. In contrast, a slower and progressive rise in serum LH and FSH was observed in subjects ovariectomized during luteal phase of the cycle. The quantitative secretion (area under the curve) during the 1st wk after ovariectomy was significantly greater in patients operated on during the follicular phase than during the luteal phase for both LH (P < 0.05) and FSH (P < 0.01). Thereafter, a similar pattern of gonadotropin rise was observed for patients ovariectonized during either phase of the cycle and reached a plateau by the end of the 3rd wk. At this time, the mean LH concentration increased 6-fold for follicular phase surgery and 8-fold for luteal phase surgery. The mean serum FSH concentration increased 8-fold for follicular phase surgery and 12-fold for luteal phase surgery. The net increase in serum FSH level was higher than that in the serum LH level after surgery in both phases of the cycle and thus a reversal of FSH/LH ratio occurred. These data provide indirect evidence that the phase of ovarian steroid secretion may exert a quantitative influence on the gonadotropin turnover rate within the hypothalamic-pituitary system. The augmented gonadotropin release and the reversal of FSH/LH ratio following ovariectomy presumably could be due to an increased gonadotropin net synthesis which is more pronounced for FSH than for LH.

Gonadotropin

10.1172/jci106587

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Citations (61)

REFINEMENTS OF THE CASEIN TURBIDITY METHOD FOR MEASURING PROTEASES IN BEER

Journal of the Institute of Brewing (1988)

C. C. TSAI D. E. Briggs

The casein turbidity method for determining papain has been modified to allow it to be used for both normal and strong beers. Problems of instant casein coagulation which occur when the original reagents are mixed with strong beers were due to inadequate control of pH, and not to high alcohol levels. Methods are given for preparing convenient substrate and activator solutions that are stable for at least 8 days at 4°C. By carrying out estimations at 60°, rather than 50° as originally proposed, incubation times are roughly halved. It is shown that weak activators, like potassium metabisulphite, can reduce enzyme activities when added to a reaction mixture which also contains cysteine. The mixing sequence of beer, activator solution and substrate solution, as well as buffer strengths, influence the observed activities of papain. Further changes which might improve the method further have been proposed.

Turbidity

10.1002/j.2050-0416.1988.tb04546.x

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The Effect of Ethinyl Estradiol Administration During Early Follicular Phase of the Cycle on the Gonadotropin Levels and Ovarian Function

The Journal of Clinical Endocrinology & Metabolism (1971)

C. C. TSAI S. S. C. YEN

Treatment with ethinyl estradiol (EE, 200 or 400 μg/day) abolishes the early follicular rise of gonadotropin levels observed in control cycles. The effect of such manipulation on subsequent gonadotropin pattern and follicular as well as luteal function were monitored by the changes in serum concentrations of FSH, LH, 17β-estradiol (E2) and progesterone. During EE treatment, a significant decline in the gonadotropin levels was observed. This negative feedback effect appears to be greater for FSH than for LH which was followed by a significant rebound increase in LH but not FSH approximately 36 hours after cessation of treatment. This transient dynamic change in gonadotropin concentration was followed by a pattern which was strikingly similar to that observed in the normal ovulatory cycle. These changes in gonadotropin levels were associated with a disturbance of normal sequence of follicular maturation as reflected by the prolongation of the follicular phase and the delayed midcycle peaks of E2 and LH. The corpus luteum function, as judged by the duration of luteal phase and progesterone concentrations, was identical between treated and control cycles.

Gonadotropin

10.1210/jcem-33-6-917

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Citations (102)

Impairment of Growth Hormone Secretion in Response to Hypoglycemia During Early and Late Pregnancy

The Journal of Clinical Endocrinology & Metabolism (1970)

S. S. C. YEN Patricio A. Vela C. C. TSAI

In order to ascertain whether the diminished pituitary growth hormone (HGH) response observed in late pregnancy may be quantitatively related to the duration of gestation, sequential studies in the HGH responses to insulin-induced hypoglycemia were made during each trimester of pregnancy and at 6–7 weeks post partum in 10 non-obese subjects. The HGH responsiveness to hypoglycemia was progressively diminished during the 3 trimesters and became blunted during the last trimester of pregnancy when compared with their own postpartum controls. Normal brisk HGH response to hypoglycemia was observed at 6–7 weeks post partum. Although the presence of a large quantity of circulating human placental lactogen may account for the inhibitory effect on the hypothalamic-pituitary HGH releasing mechanism in late pregnancy, other hormonal factors such as elevated progesterone and nonprotein-bound cortisol may play a role in the suppressive effect on HGH release during early pregnancy.

Human placental lactogen

Placental lactogen

10.1210/jcem-31-1-29

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Citations (44)

Nocturnal Patterns of Serum Gonadotropins During the Menstrual Cycle

The Journal of Clinical Endocrinology & Metabolism (1973)

Frederick Naftolin S. S. C. YEN Deborah F. Perlman C. C. TSAI DONAL C. PARKER

In order to evaluate nocturnal patterns of LH and FSH secretion in normal women, samples were drawn from 3 subjects at 20-min intervals during 6 or 7 nights of 2 ovulatory and 1 anovulatory cycles. Circulating gonadotropin patterns were pulsatile in a manner similar to that observed during previous daytime studies. The presence or absence of sleep during the collections did not affect circulating gonadotropin levels, nor was there any difference found between sleep stages and gonadotropin levels during REM and nonREM sleep. The central signal for gonadotropin release in women is not affected by sleep.

Gonadotropin

Pulsatile flow

Anovulation

10.1210/jcem-37-1-6

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Citations (26)

Effect of exogenous estrogen on carbohydrate metabolism in postmenopausal women

American Journal of Obstetrics and Gynecology (1972)

L. N. Ajabor C. C. TSAI Patricio A. Vela S. S. C. YEN

Carbohydrate Metabolism

Glucose tolerance test

10.1016/0002-9378(72)90689-8

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Citations (36)

Plasma 3 alpha, 17 beta-androstanediol glucuronide concentrations in normally menstruating Chinese women.

PubMed (1992)

Shao‐Hua Xie C. C. TSAI Rajesh S. Mathur

Hirsutism is rare in oriental women. In order to define the androgen metabolism in these women, plasma levels of androstanediol glucuronide (AG) along with testosterone (T), androstenedione (delta 4A), dehydroepiandrosterone sulfate (DHAS) and sex hormone binding globulin (SHBG) were determined in samples collected from 22 normally menstruating Chinese women. Their ages were 37.7 +/- 7.2 years (mean +/- S. D.) with a range of 27 to 46 years. All were born of Chinese parents. None were on any hormonal medication for at least one year. Compared to our local controls, no significant differences were observed in plasma androgens and SHBG concentrations. Comparable levels of AG, delta 4A and T in these two groups suggest that in Chinese women, under basal conditions, the androgen metabolism is comparable to their north american counterparts.

Basal (medicine)

hirsutism

Alpha (finance)

Source

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