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Biomedical subjects

G Tolis

Publications and source records attributed to G Tolis.

At least 127 records · Page 7Linked to original sources

L-dopa, growth hormone and adipokinesis in the lean and the obese.

Fourteen human volunteers (5 lean of both sexes, 4 grossly obese male, 4 grossly obese female, and one patient suffering from hypopituitarism) were given 500 mg of L-dopa orally, and growth hormone (HGH), cortisol, prolactin (hPRL), insulin, FSH, LH, free fatty acids (FFA) and blood glucose were determined up to 300 minutes following the drug. The lean group showed a uniformly marked increase in HGH followed by a significant FFA rise. The obese females exhibited blunted HGH and a somewhat reduced FFA response. In the obese male, there were no HGH und FFA increments. Unstimulated levels of HGH were lower and FFA markedly higher in both obese male and female vs the lean group. The patient with hypopituitarism showed no significant HGH and FFA response. In all groups, hPRL decreased, while Cortisol, LH, FSH, and blood glucose levels remained uninfluenced.

Blood Glucose↗

The acute effect of 2-bromo-a-ergocryptine (CB-154) on anterior pituitary hormones and free fatty acids in man.

CB-154 was administered to six healthy subjects in three different single doses - 1 mg, 2,5 mg, and 3 mg. Growth hormone, prolactin, follicle stimulating hormone, luteinizing hormone, cortisol, blood sugar and free fatty acids were determined. 2.5 and 3 mg doses of CB-154 induced a significant rise in growth hormone and free fatty acids, while prolactin decreased. In addition, CB-154 prevented the circadian fall of plasma cortisol. There were no changes in follicle stimulating hormone, luteinizing hormone or blood sugar levels.

Blood Glucose↗

Survival and growth in a woman with untreated hypothalamic panhypopituitarism of 21 years' duration.

A 29-year-old woman with evidence of a craniopharyngioma and documented panhypopituitarism is described. Clinical and laboratory evaluation revealed deficiencies of follicle-stimulating hormone, luteinizing hormone, thyroid-stimulating hormone, growth hormone, prolactin, adrenocorticotropic hormone and antidiuretic hormone. Prompt release of several pituitary hormones was noticed after administration of the hypothalamic releasing hormones FSH/LH-RF and thyrotropin-releasing hormone, whereas insulin-induced hypoglycemia, levodopa, chlorpromazine and clomiphene citrate, all of which act at the level of the hypothalamus, did not alter basal pituitary secretion. The patient's height of 60 inches, despite panhypopituitarism, and the interpretation of the above data are discussed in the light of current concepts regarding the dynamics of the hypothalamic-hypophyseal system.

Adolescent↗

Functional evaluation of prolactin secretion in patients with hypothalamic-pituitary disorders.

Prolactin secretion was assessed in 23 patients with hypothalamic-pituitary disorders using L-Dopa suppression, chlorpromazine (CPZ), and thyrotropin-releasing hormone (TRH) stimulation tests. Based on the responses to these tests, three groups of patients were identified: those with panhypopituitarism (group I) and those with partial hypopituitarism either with (group II) or without (group III) evidence of hypothalamic involvement. Panhypopituitary patients (group I) consistently had low serum prolactin values and failed to respond to all tests. Patients with hypothalamic involvement (group II) exhibited (a) elevated basal prolactin values. (b) an increase in serum prolactin after TRH stimulation. (c) blunted response to L-Dopa, and (d) lack of response to chlorpromazine stimulation. Patients with partial hypopituitarism but without hypothalamic involvement (group III) had normal serum prolactin levels and suppressed normally after L-Dopa; although the magnitude of response to both stimulatory agents was significantly lower than normally found the ratio of prolactin levels post-CPZ and TRH (Delta prolactin CPZ/Delta prolactin TRH) was similar to the ratio of normal individuals suggesting that these patients (group III) had a normal hypothalamic-pituitary prolactin axis. In the 23 patients studied, the most consistent disorder of pituitary function proved to be an abnormal response to one or other of the three tests employed for the evaluation of prolactin secretion. Hence these tests have considerable potential as a sensitive screening procedure in the evaluation of patients suspected of having hypothalamic-pituitary disease.

Adolescent↗

Circadian rhythms of anterior pituitary hormone secretion: effects of dexamethasone.

Circadian rhythms of hormone secretion are by now well recognized but there are limited data available to compare such rhythms of multiple hormones in individual subjects. Therefore concentrations of serum thyrotropin (TSH), cortisol, growth hormone (GH), triiodothyronine (T3) and prolactin (PRL) were determined in blood samples from six healthy males over periods of 24 hours. A circadian periodicity was identified for cortisol, GH, PRL and TSH; maximum concentrations for TSH and PRL occurred at dissimilar times, namely respectively before and after the GH peak. Maximum TSH coincided with nadir values forplasma cortisol. Dexamethasone administration (3 mg over 36 hours) lowered serum T3 concentration and abolished TSH periodicity without affecting the PRL rhythm. These data suggest that a) nocturnal TSH and PRL maximum levels do not have common mediation; b) there may be an inverse relationship between cortisol and TSH, and c) glucocorticoids at low doses preferentially affect secretion of thyrotropin.

Adult↗

Androgens and therapeutic aspects of antiandrogens in women.

OBJECTIVES: We reviewed the mechanisms of androgen actions and the established and experimental uses of antiandrogens in women. METHODS: Relevant studies were identified through a computerized bibliographic search (MEDLINE) and through manual review of bibliographies in relevant publications. RESULTS: Androgens exert major effects on the functions of gonads, sex organs, and various "nonreproductive" organs and systems, including muscles, liver, skin, nervous system, and the immune system. Most, but not all, of the actions of androgens may be explained by their binding with specific androgen receptors. Antiandrogens prevent androgens from expressing their activity at target cells. They act primarily by binding to androgen receptors and thus preventing activation of receptors by androgens. Steroidal antiandrogens may also exert a wide range of other hormonal and antihormonal effects by interacting with receptors for progesterone, glucocorticoids, and mineralocorticoids. Furthermore, some antiandrogens may decrease the production of androgens by acting at the hypothalamic-pituitary unit and modifying the release of LH, or by directly inhibiting individual enzymes involved in steroidogenesis. Antiandrogens are widely used in the treatment of women with various hyperandrogenic conditions, including polycystic ovary syndrome, idiopathic hirsutism, acne, seborrhea, and hair loss. CONCLUSIONS: Antiandrogens provide a logical and clinically effective pharmacotherapy of hyperandrogenic disorders. However, both steroidal and nonsteroidal antiandrogens may cause significant side effects, largely because of their interactions not only with androgen receptors, but also with other receptors and various enzymatic activities. Difficulties in designing the optimal antiandrogen largely result from the complexities of androgen metabolism and action in various tissues.

Androgen Antagonists↗

Octreotide effect on ovarian morphology in insulin-resistant PCOS patients following six-month decapeptyl treatment.

PROBLEM: Regulation of ovarian folliculogenesis involves bidirectional communication between the immune and endocrine systems. Somatostatin analogues have been reported to acutely suppress elevated androgens in polycystic ovary syndrome (PCOS). The aim of our study was to analyze the morphologic and hormonal-metabolic response to octreotide therapy for one month in insulin-resistant PCOS patients in whom luteinizing hormone (LH) effect had formerly been separated by a six-month GnRH-agonist (GnRH-a) course. METHOD: Fifteen PCOS patients were studied two months after completing a six-month GnRH-a (decapeptyl 3.75 mg monthly injection) course. Seven of the patients (group A), who were insulin-resistant and gave hyperinsulinemic response to a glucose challenge, received a 50-micrograms subcutaneous injection of octreotide twice a day for one month. The nonhyperinsulinemic patients (group B) received placebo injections. Hormonal measurements, oral glucose tolerance test (OGTT), and transvaginal ovarian ultrasound were performed before and toward the end of the treatment period. RESULTS: After octreotide ovarian volume dropped significantly in group A (x +/- SD) (19.2 +/- 5.1 versus 14.7 +/- 5.5 cc, P = .02). LH levels increased (3.25 +/- 1.22 versus 5.95 +/- 4.34 mu/ml, P = .05) as did E2 levels (38.0 +/- 11.4 versus 55.1 +/- 12.7 pg/ml, P = .005). There was no change in follicle-stimulating hormone, 17-hydroxy-progesterone, free testosterone, or androstenedione levels. Insulin secretion during OGTT dropped significantly (555 +/- 294 versus 68 +/- 29 mu u/ml/hr, P = .002). Glucose tolerance was not affected. In contrast, the placebo-treated group B patients showed an increase in ovarian volume (10.9 +/- 3.5 versus 14.8 +/- 3.3 cc, P = .001) while their gonadotropin and steroid profile relapsed, similarly to our patients receiving octreotide. CONCLUSIONS: Octreotide has an adjunctive beneficial effect to GnRH-a on ovarian morphology although, at the dose used, there was no suppression of gonadotropin or ovarian steroid levels. The changes in ovarian morphology are probably mediated through suppression of insulin levels and/or other ovarian growth factors.

Adolescent↗

Human growth hormone and gonadotropin releasing hormone analog combination therapy increases predicted height in short normal girls.

The "short normal" child constitutes a real challenge for the pediatric endocrinologist. In a subgroup of short normal children, puberty starts at a normal age but with low height, and hence, the final height is expected to be quite compromised. Efforts to improve the outcome in this group have been made in the past with equivocal results. We present the growth data of 8 short girls with normal growth hormone values on provocative testing and low height at puberty initiation. At intervention the height and the stage of puberty were 129.3 +/- 5 cm and II to III, respectively, and the predicted height was 148.8 +/- 2.6 cm. Gonadotropin releasing hormone analog, triptorelin (3.6 +/- 0.5 microg/kg/day) and growth hormone (0.5 IU/kg/week) were used in different sequential order and simultaneously in each child. The mean total treatment period was 47.6 +/- 11.2 months. The mean predicted and the mean final height in the total group were 148.8 +/- 2.6 and 154.5 +/- 3.6 cm, respectively (p:0.028). The final height did not differ from the target height (154.8 +/- 8 cm versus 154.5 +/- 3.6 cm), while in 4 children, the final height was greater than the target height. The height gain (delta Final height - Predicted height) was 5.7 +/- 1.3 cm. If we analyze separately the girls in whom growth hormone was started first and gonadotropin releasing hormone analog followed versus those who started the analog first, the delta Final height - Predicted height was 8 +/- 3 cm in the former and 4.8 +/- 3.1 cm in the latter (p:0.03). It seemed that the difference was accounted for by duration of growth hormone therapy (51.3 +/- 10.6 months versus 28.6 +/- 10.6 months) (p:0.026), rather than by other factors. In conclusion, under the conditions of the present study, the combination of puberty arrest and growth hormone therapy significantly improved predicted height. The most significant determinant of the height gain was the duration of growth hormone therapy.

Age Determination by Skeleton↗

Growth hormone release by the novel GH releasing peptide hexarelin in patients with homozygous beta-thalassemia.

Patients with beta-thalassemia often present with abnormalities in growth and other endocrine functions. Growth hormone (GH) secretion is controlled via somatostatin and growth hormone releasing hormone (GHRH). Recently, Hexarelin, a new potent GH secretagogue (His-D-2-Methyl-Trp-Ala-Trp-D-Phe-Lys-NH2), was synthesized. Our study was designed to assess and compare its efficacy as a GH secretagogue to GHRH 1-29 in beta-thalassemia. Eighteen patients, regularly transfused and chelated, were studied; 11 were short statured. None had diabetes mellitus, hypothyroidism, hypopara-thyroidism or major organ failure. We measured GH at 0, 30, 60, 90, 120 min after GHRH 1-29 or Hexarelin administration. Hexarelin p.o. or i.v. evoked a brisk rise of serum GH which was significantly higher (p < 0.01) than that induced by GHRH 1-29 i.v. In conclusion, Hexarelin has greater GH releasing capacity than GHRH 1-29 at 1 microgram/kg i.v. and can thus be viewed as a potential therapeutic agent in GH deficient states.

Adolescent↗

Pituitary non-secreting macroadenoma apoplexy in an adolescent. patient report and review of the literature.

Pituitary macroadenomas are rare in children and adolescents, and when encountered are usually hormone secreting. Symptomatic pituitary non-secreting macroadenoma apoplexy in an adolescent is rare and potentially life-threatening. A 15 year-old patient is described, hospitalized due to headache, fever and photophobia 4 days prior to admission. A meningeal syndrome was postulated, based on clinical examination and cerebrospinal fluid testing. However, clinical examination and hormone testing revealed partial failure of the anterior pituitary. Computed tomography of the brain demonstrated a space-occupying lesion of the pituitary. Magnetic nuclear resonance imaging suggested the presence of a pituitary macroadenoma. Hypophysectomy was performed. Histological examination revealed an extensive infarction of a pituitary adenoma. Hormonal substitution with thyroxine and corticosteroids was administered. This report emphasizes that pituitary non-secreting macroadenoma apoplexy may rarely be the cause of headache and fever in an adolescent, thus causing difficulties in differential diagnosis from acute meningitis.

Adenoma↗