Showing papers by "Christina Wang published in 1979"

FSH induction of functional LH receptors in granulosa cells cultured in a chemically defined medium.

Abstract: THE rat ovarian granulosa cell is an excellent model for studying the mechanisms and control of hormone-dependent cell differentiation. During graafian follicle development, the granulosa cells sequentially develop specific membrane receptor sites for follicle-stimulating hormone (FSH)1,2 and luteinising hormone (LH)3. In vivo studies on the mechanism of granulosa cell differentiation have established that FSH induces the appearance of the LH receptor sites in the granulosa cell4,5. The FSH-induced increase in LH receptors is essential for preparing the graafian follicle for the pre-ovulatory surge of LH which initiates ovulation and subsequent luteinisation of the granulosa cells. Studies of cultured granulosa cells have led to the suggestion that the FSH induction of LH receptors is not a direct process but requires an interaction between the granulosa cell and other ovarian cell types, a concept consistent with the known importance of cell–cell interaction in cell differentiation6. This hypothesis stemmed from the observation that LH receptors can be induced by FSH in granulosa cells in vivo and in organ cultures of intact ovarian follicles, but not in isolated granulosa cells cultured as monolayers in medium containing serum7,8. We show here that the inability of previous workers7,8 to induce LH receptors in isolated granulosa cells may have been due to the use of serum in their tissue culture medium. We demonstrate that specific, high-affinity LH/hCG receptors can be induced by FSH in isolated granulosa cells cultured in a chemically defined medium, but not in isolated granulosa cells cultured with serum. In addition, we show that these receptors are capable of mediating important steroidogenic responses.

Effects of heroin addiction on thyrotrophin, thyroid hormones and prolactin secretion in men

Abstract: Pituitary-thyroid function in male heroin addicts and addicts after abstinence (ex-addicts) was studied and compared with that of healthy euthyroid men. In heroin addicts the increases in circulating total thyroxine and triiodothyronine levels were accompanied by an increase in the thyroid hormone uptake test. These changes may reflect a quantitative increase in thyroxine binding globulin. Reverse triiodothyronine concentrations in heroin addicts were normal. The thyrotrophin-releasing hormone elicited a diminished thyrotrophin response in heroin addicts which was significantly different from that in control subjects and ex-addicts. An elevation of serum prolactin was noted in heroin addicts, while ex-addicts had normal levels. Gradual recovery of pituitary-thyroid function occurred after heroin withdrawal.

Treatment of acromegaly with bromocriptine.

Abstract: Summary: Five men and three women with active acromegaly were treated with bromocriptine After three months' therapy (30 mglday) mean GH during the day decreased by 50% in six out of eight subjects In the remaining two subjects (non-responders) GH was persistently over 100 μg/1 Mean GH during glucose tolerance test were not significantly decreased in three out of the eight subjects, of whom two were the non-responders The minimum dose of bromocriptine required to achieve maximum GH suppression ranged from 7·5 to 20 mglday In contrast, serum prolactin (PRL) throughout the day suppressed significantly in all subjects after 5 mglday bromocriptine Decreases in clinical symptoms, hand volume, urinary hydroxyproline and calcium excretion were seen in about half of the subjects Three of the four subjects with diabetes metlitus showed improvement in glucose tolerance Although minor side effects were uncommon, one patient died because of massive gastrointestinal haemorrhage from a duodenal ulcer

Thyrotropin: α- and β-Subunits of Thyrotropin, and Prolactin Responses to Four-Hour Constant Infusions of Thyrotropin-Releasing Hormone in Normal Subjects and Patients with Pituitary-Thyroid Disorders*

Abstract: TRH was administered as a 4-h constant rate iv infusion (0.4 µg/min) to eight healthy euthyroid volunteers, three euthyroidfemales on estrogen, eight hyperthyroid patients, eight patients with primary hypothyroidism, and five patients with hypothalamic and pituitary disorders. Blood was collected at regular intervals for the measurements of TSH, α and β-TSH subunits, T3 and PRL. Healthy euthyroid subjects exhibited biphasic increases in intact TSH as well as in α- and β-TSH subunits. Circulating TSH levels rose rapidly within 10 min of infusion to a peak in 45 min. Levels were then stable or decreasing until 90 min, when a second phase of increase occurred which was maximal at160 min. Greater responses were observed in females than in males. Primary hypothyroid patients exhibited similar biphasic increases in TSH and itssubunits as did euthyroid subjects. Patients with hypothalamic and pituitary disorders had delayed and diminished responses, while thyrotoxic patientsdid not respond at all. In euthyroid s...

Dissociated thyroxine, triiodothyronine and reverse triiodothyronine levels in patients with familial goitre due to iodide organification defects*

Abstract: The thyroid function of patients with three different types of organification defect was studied. All patients were characterized by a high thyroidal 131I uptake and a positive perchlorate discharge. Patients with Pendred's syndrome who had goitre and congenital nerve deafness were mostly euthyroid with normal circulating thyroid hormone levels. Only two of them had compensated euthyroidism with elevated total T3, high basal TSH and delayed return to basal value with TRH. The patients who were euthyroid with large goitres and normal hearing had elevated total T3 and an exaggerated TSH response to TRH. The thyroid function of these two groups of patients contrasted with that of goitrous cretins, who were clinically hypothyroid with low circulating total T4, increased T3 and decreased rT3 levels. The data suggest that in patients with intrathyroidal iodine deficiency secondary to organification defect, there is preferential T3 production in an effort to maintain euthyroid state, and this is further substantiated in the case of gross thyroid insufficiency either by enhanced peripheral conversion of T4 to T3, or reduced metabolic clearance of T3 and increased clearance of rT3, resulting in elevated T3 and decreased rT3 levels.