Incidence of hypothyroidism after radioactive iodine therapy for thyrotoxicosis in Hong Kong Chinese

The incidence of hypothyroidism in 1396 Chinese patients in Hong Kong treated for hyperthyroidism with 131I therapy is presented using the life-table method of analysis. One year after therapy only 6% of patients were hypothyroid, but the subsequent annual incidence was 3.5%, emphasising the need for life-time surveillance of these patients. A higher incidence of subsequent hypothyroidism was found in patients with diffuse surgical treatment, the total dose or number of doses of 131I, the severity of thyrotoxicosis and the age of the patient did not influence the rate of onset of hypothyroidism. The data suggest that in order to minimise the occurrence of hypothyroidism a lower dose of 131I per gram of thyroid mass should be used for patients with small diffuse glands.

Hyperfunctioning intrathyroid parathyroid gland: a potential cause of failure in parathyroid surgery

Four patients with hyperfunctioning intrathyroid parathyroid are reported. In each case the intrathyroid parathyroid was embedded within the thyroid parenchyma and appeared as a solitary 'cold' thyroid nodule by radioactive iodine scanning. It is believed that the intrathyroid parathyroid evolves as the lateral lobe of the thyroid fuses with the isthmus in the early development of the thyroid. Embryologically, and intrathyroid parathyroid is thus likely to be the superior gland. When the superior parathyroid gland is missing at the time of exploration, a nodule within the ipsilateral lobe of the thyroid may well be an intrathyroid parathyroid. Under these conditions, lobectomy for the exclusion of such a gland is mandatory.

Acute steroidogenic responsiveness to human luteinizing hormone in hypogonadotropic hypogonadism

The responses of circulating levels of androgens, estrogens, and their C-21 biosynthetic precursors to a 6-h constant infusion of human Lh (hLH; 2000 IU) were studied in four males with hypogonadotropic hypogonadism (HH) and compared with those in normal male controls. Although similar levels of circulating LH were achieved, the initial and secondary increases in testosterone were significantly greater in the hypogonadotropic subjects than in the normal controls. In contrast, the responses of estradiol, estrone, 17 alpha-hydroxyprogesterone, and 17 alpha-hydroxypregnenolone to exogenous hLH were significantly lower in HH than in normal controls. The data demonstrate a different pattern of testicular steroidogenic responsiveness after pharmacological doses of hLH, with increased concentrations of circulating testosterone in subjects with HH compared to a disproportionate increase in estrogen and progestin levels in normal men.

Prolactin inhibition of estrogen production by cultured rat granulosa cells

The effect of prolactin (PRL) treatment on estrogen production by rat granulosa cells was investigated in vitro. Immature, hypophysectomized, DES-treated rats were injected for 2 days with FSH to induce aromatase enzymes and receptors for PRL and LH. After FSH priming, the granulosa cells were cultured for 4 days in serum-free medium containing 10(-7) M androstenedione and purified FSH, LH and/or PRL. A dose-related inhibition of estrogen production from control cells was observed following PRL treatment in which 1 micrograms/ml of PRL inhibited estrogen formation by > 90%. In these same cultures, PRL caused a dose-related increase in progesterone and 20 alpha-dihydroprogesterone secretion. Treatment with purified FSH or LH stimulated estrogen synthesis by 3-10-fold. Concomitant treatment with PRL suppressed the FSH- and LH-induced increases in estrogen production in a dose-dependent manner; 1 micrograms/ml PRL suppressed estrogen production by > 80% during days 2-4 of culture. In these same cultures, PRL did not alter the stimulatory effects of FSH and LH on progesterone and 20 alpha-dihydroprogesterone production. These experiments demonstrate that PRL acts directly on rat granulosa cells in vitro to suppress basal and gonadotropin-induced increases in estrogen production.

Effect of combination chemotherapy on pituitary-gonadal function in patients with lymphoma and leukemia

After at least four courses of intermittent chemotherapy, 14 of the 15 men with malignant lymphoma had elevated serum follicle-stimulating hormone (FSH). In three of these subjects, serial studies showed progressive increases in basal FSH and exaggerated FSH responses to luteinizing hormone releasing hormone (LHRH). Although gonadal biopsies were not done, this elevation of FSH is indicative of progressive and severe damage to the germinal epithelium by chemotherapy. Elevated leutinizing hormone (LH) was found in seven and decreased testosterone (T) in two of these subjects. Increased LH responses to LHRH stimulation were also found in the three subjects studied. These findings suggest that the testicular damage is not restricted to the germinal tissue. In four male subjects with acute myeloid leukemia treated by intermittent chemotherapy not containing any alkylating agents, FSH, LH, and T levels were normal. Three of the 4 female patients with malignant lymphoma and two with acute myeloid leukemia had normal basal, serial, and LHRH-stimulated FSH, LH, and estradiol (E2) levels. Elevated gonadotropins and low E2 were found only in subjects who had received abdominal irradiation.

The 68,000-dalton neurofilament-associated polypeptide is a component of nonneuronal cells and of skeletal myofibrils

Purified preparations of 10-nm neurofilaments from rat spinal cord and bovine or porcine brain contain a predominant 68,000-dalton polypeptide. This polypeptide is also a major component of the neurofilaments that copurify with brain tubulin isolated by cycles of polymerization and depolymerization. A protein that has the same isoelectric point and molecular weight as the neurofilament-associated polypeptide has also been identified as a cytoskeletal protein in a variety of avian and mammalian cell types, including baby hamster kidney (BHK-21) mouse 3T3, Novikoff rat hepatoma, chicken fibroblast, and chicken muscle cells. This protein is also a component of isolated chicken skeletal myofibrils. One-dimensional peptide maps of the 68,000-dalton proteins purified by two-dimensional isoelectric focusing/NaDodSO(4)/polyacrylamide gel electrophoresis from myofibrils, cycled tubulin, purified neurofilaments, and various cultured cell types were identical. In immunofluorescence this protein was associated with cytoplasmic intermediate filaments and myofibril Z discs. These results indicate that the neurofilament-associated polypeptide is a conserved protein that is present in many different cell types in addition to neuronal cells. Because some of these cells contain the major components of two other intermediate filament classes, desmin and vimentin, a given cell type may contain the subunits of at least three distinct intermediate filament types.

Use of low-dosage oral cyproterone acetate as a male contraceptive

To ascertain the effects of low-dosage cyproterone acetate (CPA) on the reproductive and endocrine functions of normal men, 25 volunteers were given CPA 0, 5 or 10 mg daily over 16 weeks, preceded by 12 weeks pretreatment observation and followed by 24 weeks posttreatment follow-up. CPA caused a decrease in sperm concentration, percentage motility, proportion of normal sperm and ability of the sperm to penetrate a column of cervical mucus in most patients. In addition, circulating testosterone, estradiol, LH and FSH levels were significantly reduced during treatment. All these changes reverted to the pretreatment level upon drug withdrawal. These findings suggest that firstly, although low dosage CPA was able to induce changes in seminal analyses, azoospermia was present in only one out of 15 subjects exposed to the drug. Secondly, the marked decrease in androgen levels associated with CPA treatment renders CPA unsuitable as a single entity agent for long-term male contraception.

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

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.

Treatment of acromegaly with bromocriptine

Five men and three women with active acromegaly were treated with bromocriptine. After three months' therapy (30 mg/day) 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 micrograms/l. Mean GH during glucose tolerance test were not significantly decreased in three out of the eight subjects, of whom two were the nonresponders. The minimum dose of bromocriptine required to achieve maximum GH suppression ranged from 7.5 to 20 mg/day. In contrast, serum prolactin (PRL) throughout the day suppressed significantly in all subjects after 5 mg/day 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 mellitus showed improvement in glucose tolerance. Although minor side effects were uncommon, one patient died because of massive gastrointestinal haemorrhage from a duodenal ulcer.

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

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.

The effect of heroin addiction on pituitary-testicular function

The effect of heroin addiction on pituitary-testicular function was studied in 54 active and 19 abstinent addicts and their results were compared with those of 43 age-matched controls. Abnormal sexual function was frequently found in heroin addicts and this persisted after drug withdrawal. The mean total (mean +/- SE, 18.1 +/- 1.0 nmol/1) and free (0.17 +/- 0.03 nmol/1) testosterone (T) levels in heroin addicts were significantly lower than those in healthy controls (total T 22.8 +/- 1.1 nmol/1), P less than 0.005; free T 0.30 +/- 0.03 nmol/1, P less than 0.005). The mean sex hormone binding globulin binding capacity was higher in heroin addicts (60.1 +/- 5.2 mM) than in healthy controls (35.5 +/- 2.1 mM). These hormonal changes returned promptly to normal after withdrawal. The basal LH and FSH and the responses to LHRH were comparable in the three groups studied. The finding of significantly lower total and free T together with higher SHBG indicates an abnormal testicular function in heroin addiction. Normal basal and LHRH-stimulated LH and FSH levels suggest that chronic heroin abuse depressed testicular function via the hypothalamus or higher centres.

An automated tumor resection device for neurological surgery

A pneumatically activated cutting probe has been designed for the neurosurgical removal of nervous system tumors or diseased tissue. The hand-held probe is formed of concentric slender tubes, one reciprocating inside the other. A scalpel-sharp edge on the tip of the inner tube moves in a shear motion past a stationary port on one side near the distal end of the outer tube. The reciprocating motion of the inner tube is provided by a pneumatic power source housed in a separate control console.

Effect of acute myocardial infarction on pituitary-testicular function

The effect of acute myocardial infarction on the secretions of LH, FSH and testosterone was studied in thirteen male patients. Plasma testosterone fell transiently on the fourth day after acute myocardial infarction. This was accompanied by a rise in LH on the same day which persisted for a week after infarction. Serum FSH showed no significant change. The data suggest that following the medical stress of myocardial infarction, testosterone concentration was suppressed resulting in a compensatory rise in LH.

Effect of surgical stress on pituitary-testicular function

The effect of surgical stress on the secretions of LH, FSH, testosterone (T) and oestradiol (E2) were studied in twelve male patients. During surgery LH rose significantly; post-operatively, LH fell but remained persistently elevated a week after operation. However, T and E2 fell progressively to a nadir on the second and fifth post-operative day respectively and remained suppressed. Serum FSH showed no significant change. Despite a post-operative decrease in sex hormone binding globulin (SHBG) binding capacity, non-SHBG bound T showed a decrease parallel to T. Multiple sampling studies showed that the secretions of LH were increased and that of T were decreased post-operatively. Following surgery, LH responses to LHRH were magnified, FSH and T responses showed no significant change when compared with the pre-operative responses. These data suggest that secretions of LH were increased during surgery. Following surgical stress, T and E2 concentrations were suppressed resulting in a compensatory elevation of LH concentrations.