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Biomedical subjects

B H Yuen

Publications and source records attributed to B H Yuen.

At least 91 records · Page 5Linked to original sources
PubMed1984

Steroidogenic capabilities of various compartments of rat ovarian follicles in culture.

The production of progesterone, estrogen and androgen as well as the metabolism of radiolabelled progesterone by various cellular components of rat ovarian follicles were studied. Granulosa (G), theca (T), recombined granulosa plus theca (G+T) and intact follicular wall (FW) of ovaries from immature rats treated with pregnant mare serum gonadotropin (8 IU) were cultured for 24 h in the presence or absence of [4-14C]progesterone. The estrogen and androgen accumulation when calculated per follicle was several fold greater in FW than in G, T, or G+T preparations. The conversion of radiolabelled progesterone to its identified C21 catabolites (20 alpha-hydroxy-4-pregnen-3-one and 3 alpha-hydroxy-5 alpha-pregnan-20-one) was significantly lower in FW than in G+T incubations. Conversely, the metabolism of radiolabelled progesterone to androsterone was several fold greater in FW than in G+T incubations. Addition of hydroxyflutamide to FW incubations significantly decreased estrogen production and increased the conversion of radiolabelled progesterone to androsterone. Estrogen production by follicular wall may be enhanced by androgenic stimulation of aromatase activity as well as by a structure-dependent factor(s) of a yet unknown nature, both of which may decrease progesterone catabolism to biologically inactive progestins while promoting progesterone conversion to androgens and eventually to estrogens.

Androgens↗
PubMed1983

The role of prostaglandin F in the symptoms of endometriosis.

Prostaglandin F (PGF) levels in endometriotic tissue in vitro have been shown to be higher than the levels in healthy ovarian tissue and uterine endometrium. The results of a study of nine women with endometriosis support this finding and suggest that prostaglandins have an important role in the pathogenesis of the symptoms and infertility in such women.

Endometritis↗
PubMed1982

Regression of pituitary microadenoma during and following bromocriptine therapy: persistent defect in prolactin regulation before and throughout pregnancy.

During 5 years of clinical, endocrinologic, and radiologic observations in a woman with a microprolactinoma treated medically with bromocriptine for 29 months, serial hypothalamic-pituitary studies revealed a defect in lactotrope function after prolactin (PRL) concentrations and ovulation were restored to normal. This defect persisted throughout a spontaneously conceived pregnancy in which the PRL, estradiol, and progesterone levels were subnormal, while, the dehydroepiandrosterone sulfate levels were normal and estriol concentrations were elevated. Levels of the beta subunit of human chorionic gonadotropin (hCG) were close to and slightly above the normal ranges. These observations are consistent with a role for PRL, interacting with hCG, in the control of estrogen and progesterone secretion by the fetoplacental unit. Lactation was initiated and maintained post partum. Pituitary function and PrL responses to suckling suggested improved lactotrope function 22 to 25 months after withdrawal of bromocriptine. The impaired lactotrope function, therefore, did not preclude normal implantation, pregnancy maintenance, onset of parturition, fetal development, and lactation.

Adenoma↗
PubMed1982

Menstrual cycle changes with marathon training: anovulation and short luteal phase.

Fourteen normal women (self-selected from 180 women enrolled) in a marathon training clinic kept basal body temperature (BBT), mileage, and weight records for 48 cycles before the marathon. Entry criteria were: Age 20-45, gynecologic age greater than 5 years, no hormone use, or weight change in 3 months. The women were 35.2 +/- 5.6 years in age, 22.6 +/- 5.1 years gynecologic age, runners of 4.1 +/- 2.5 years with premenstrual symptoms, previous pregnancy 4/14, no infertility and 2/14 remote amenorrhea. BBT records were obtained and analyzed by Vollman's criteria (1977). There was no weight loss. 32/48 cycles were biphasic but only 16 were normal in the length of the premenstrual phase (PreM = luteal, nl 10 - 16 d) with a mean of 11.1 +/- 1.2 days. The other 16 biphasic cycles had short PreM phase of 6.4 +/- 1.8 days. Monophasic (M = anovulatory) cycles occurred in 16/48 records. Cycles which were abnormal (Short PreM and M) differed only in that usual run length was longer (9.6 - 9.9 miles) than in normal cycles (7.9 +/- 2.4 miles). Marathon training may be associated with normal length but M and short PreM type cycles.

Adult↗
PubMed1981

Regulation of ovarian follicular and luteal function during treatment with exogenous gonadotropins in anovulatory infertility.

The dosage, duration of treatment, and plasma hormone levels were analyzed statistically between and within groups of treatment cycles with (n = 46) and without (n = 10) ovulation. A significant difference was observed in the dosage of human menopausal gonadotropins (hMG) over various days of treatment, but not in the mean dosage of hMG and human chorionic gonadotropin (hCG) administered per cycle. Follicle-stimulating hormone (FSH):luteinizing hormone (LH) ratios, prolactin (PRL) levels, and the magnitude and the duration of the estradiol response were greater in the ovulatory cycles. Additionally, in the ovulatory cycles, the dose of hMG correlated with the plasma levels of estradiol, FSH, and LH, while in the anovulatory cycles, hMG dosage correlated only with the LH concentrations. After administration of hCG, the mean plasma concentrations of its beta subunit peaked within 1 day and remained detectable for up to 10 days thereafter. In the ovulatory cycles, the mean progesterone level was maximal 6 days following hCG administration. In these cycles, luteal phase progesterone levels correlated positively with the preovulatory estradiol and inversely with concentrations of the beta subunit of hCG. The data demonstrate that, in contrast to anovulatory follicles, ovulatory follicles were exposed to a relative "dominance" of FSH over LH, with higher concentrations of estradiol and PRL for several days before hCG was administered. Apart from hMG dosage, the endogenous discharge of LH appeared to be an important determinant of the ovarian response. A single 10,000 IU dose of hCG was adequate for inducing ovulation and maintaining luteal function.

Adult↗
PubMed1981

Molar pregnancy in British Columbia: estimated incidence and postevacuation regression patterns of the beta subunit of human chorionic gonadotropin.

A total of 171 cases of molar pregnancy were followed by serial radioimmunoassay of the beta subunit of human chorionic gonadotropin (hCG-beta) over a 4-year period. The incidence over the study interval was 1:1,202 pregnancies in the province. In 120 women with intact uteri and measurable plasma levels of hCG-beta at the initiation of follow-up, the hormone remained detectable for up to 219 days (between 31 and 32 weeks) following evacuation, with 50% of patients remaining positive at 63 days (between 8 and 9 weeks). In five women undergoing hysterectomy, the hormone remained detectable for up to 112 days (between 15 and 16 weeks) postoperatively. In 92% of the cases, hCG-beta regressed to negative without chemotherapy. The prolonged presence of hCG in plasma after evacuation of the mole, regardless of the presence or absence of the uterus, points to persistence of molar tissue and its gradual rejection from uterine and extrauterine sites as a common phenomenon in the natural history of the uncomplicated postmolar course of this disease.

Adolescent↗
PubMed1981

Human chorionic gonadotropin, estradiol, progesterone, prolactin, and B-scan ultrasound monitoring of complications in early pregnancy.

In a prospective study of women in the first trimester who were at risk for recurrent abortion, data from 20 pregnancies with normal outcomes were contrasted with those of 9 pregnancies that aborted spontaneously between 7 and 12 weeks. In pregnancies in which an embryo was present before abortion, the mean concentrations of human chorionic gonadotropin beta-subunit (hCG-beta) were low with a steady decline in progesterone levels, whereas estradiol (E2) and prolactin concentrations approximated those in normal pregnancies. With growth disorganization, mean hCG-beta, E2, and progesterone levels were significantly lower than normal. In 87.5% of embryopathic pregnancies, conclusive evidence of this disorder was obtained with ultrasound monitoring. Subnormal levels of hCG-beta, E2, and progesterone were observed in 88.9, 100, and 57.1%, respectively. The karyotype was abnormal in 80% of embryopathic pregnancies successfully cultured. The normal production of E2 appeared dependent on the presence of the embryo in the first trimester of pregnancy. Endocrine failure of the trophoblast and/or the corpus luteum in embryopathic pregnancy is suggested by diminished hCG-beta and progesterone concentrations. Serial ultrasound scanning and hormone assay, particularly of hCG-beta and E2, may be useful in assessing pregnancy at risk for recurrent abortion. However, because subnormal hormone levels may occur relatively late in the clinical course of embryopathic gestation, ultrasound scanning may yield more useful results as compared with hormone assay. Further studies are required to define more clearly the mechanisms of endocrine failure in embryopathic pregnancy.

Abortion, Spontaneous↗
PubMed1980

Prolactin and the renin-aldosterone axis in human pregnancy.

In view of observations suggesting an osmoregulatory role for prolactin (PRL) and the central role of the renin-aldosterone system in the regulation of pressure-volume homeostasis, this study was undertaken to determine whether acute drug-induced alterations in circulating PRL had any effect on mean arterial blood pressure (MAP), serum osmolality, and the renin-aldosterone response during early pregnancy. Bromocriptine suppressed mean baseline PRL by 83% (p > 0.05), whereas chlorpromazine increased it more than twofold (p < 0.05) during a 180-minute study period. MAP, mean serum osmolality, plasma renin activity, and aldosterone concentrations were not significantly different from mean baseline values after the administration of either drug. These data suggest that, during early pregnancy, the renin-aldosterone axis is independent of PRL and resistant to the beta-adrenergic agonist effect of chlorpromazine.

Adult↗
PubMed1979

Plasma prolactin, human chorionic gonadotropin, estradiol, testosterone, and progesterone in the ovarian hyperstimulation syndrome.

Plasma prolactin, estradiol, progesterone, and testosterone, but not HCG-beta levels, were higher in a patient who developed the ovarian hyperstimulation syndrome while undergoing ovulation induction with human gonadotropins than in two other women who also became pregnant after similar treatment without complications. These results suggest that hyperprolactinema, in association with elevated ovarian steroid levels, may be factors in the pathogenesis of this disorder.

Blood Proteins↗
PubMed1978

Embryonic development in consecutive specimens from recurrent spontaneous abortions.

Although habitual abortion occurs in a relatively small number of patients, its successful management is often difficult. Etiologic factors may be either maternal or embryonic or both; there is much information available on maternal factors but little is known of factors related to the embryo. Information obtained from examining and karyotyping the aborted embryo or fetus may be of considerable importance in determining the possible cause of the abortion and subsequent investigation and counseling of the patient. At least two specimens from over 50 women who have had two or more consecutive spontaneous abortions have been examined and the results show that: (1) Patients aborted conceptuses of the same developmental stage, i.e., embryo or fetus, in consecutive pregnancies. This suggests that investigation should be directed to factors which may be important in the stage of pregnancy indicated. (2) Late abortions were associated with normal fetal development and factors related to the uterine environment. (3) The conceptus in an early abortion was significantly more likely to have a cytogenetic abnormality, suggesting a problem at, or prior to, conception/fertilization. A case study is also included.

Abortion, Habitual↗
PubMed1978

Maternal plasma and amniotic fluid prolactin levels in normal and hypertensive pregnancy.

Prolactin levels in the plasma and amniotic fluid of 121 normal pregnant women, 78 women with pre-eclampsia and 30 women with essential hypertension complicating pregnancy were determined by radioimmunoassay. Mean prolactin levels in plasma, but not in amniotic fluid, were significantly lower than controls in the group with pre-eclampsia (P less than 0.01) and in the group with essential hypertension (P less than 0.05). These findings suggest altered production and/or clearance of prolactin from the maternal compartment in these patients and may explain their increased response to pressor agents.

Adolescent↗
PubMed1977

Treatment of trophoblastic neoplasia at the Cancer Control Agency of British Columbia.

Over a period of 29 years 30 patients with gestational trophoblastic neoplasia were referred to the Cancer Control Agency of British Columbia. Five patients had benign disease and required no further treatment after having had dilatation and curettage. The remaining 25 patients were treated with methotrexate or hysterectomy, or both. Actuarial survival rates were 96.4% at 1 year and 90.6% at 5 years. There was a high correlation between malignancy and high titres of human chorionic gonadotropin (HCG). All cases of hydatidiform mole must be followed closely by means of estimations of HCG titre.

Adult↗