A sensitive double antibody radioimmunoassay for Human Growth hormone (HGH): levels of serum HGH following rapid tolbutamide infusion

Summary A double antibody radio-immunoassay for human growth hormone is described. — The assay can detect 0.0625 mg HGH/ml serum and has good reproducibility. It was found that: 1. a highly pure labelled hormone; 2. a specific and very potent guinea pig antihuman growth hormone antibody; and 3. at least five days of incubation for the first reaction were necessary to achieve this accuracy and sensitivity. -Porcine and rat growth hormone, sera from cow, guinea pig, rabbit, mouse, and toad fish did not react with the guinea pig anti-HGH serum used in the assay. — In four patients after hypophysectomy, HGH concentrations disappeared almost completely, and in another patient no rise of the hormone was seen during an IV insulin tolerance test.-Undiluted human serum appears to produce falsely high levels of HGH. — Normal males exhibited fasting HGH levels from 0 –2.2 mg/ml (mean 0.8 mg/ml). Females ranged from 0.6–15.0 mg/ml (mean 5.1 mg/ml) and 15 acromegalics from 8.0–103.0mg/ml (mean 31.2 mg/ml). — During a rapid tolbutamide tolerance test, serum HGH rose between 2.5- and 82-fold over the fasting levels within 10 to 70 minutes following the glucose nadir.Performed in part during a postdoctoral fellowship Stiftung Volkswagenwerk, Germany.     

Daily production and metabolic clearance of growth hormone in juvenile diabetes mellitus

Summary Daily production (PR) of human growth hormone (HGH) was calculated in patients with juvenile diabetes and control subjects by determining metabolic clearance rate (MCR) of¹³¹I HGH, at equilibrium, and mean endogenous HGH levels throughout a 24 h day. Half hourly sampling or a constant withdrawal pump were used to obtain an integrated mean endogenous HGH level. MCR (liters/day) was significantly reduced in all diabetic subjects both in absolute terms (96 ± 15 vs 274 ± 37) and relative to surface area (62 ± 8 vs 171 ± 21) (p < 0.01). Mean HGH levels were 8.4 ng/ml in the diabetics and 5.5 ng/ml in age matched controls. Daily HGH PR in the diabetic subjects (339 to 1365 g/day) did not exceed values in the control subjects (1005–1426 g/day). The results indicate that the elevated plasma HGH levels and increased HGH response to stimuli observed in diabetes, reflect reduced metabolic clearance, rather than increased pituitary secretion.     

Inhibition of biological activity of multiplication-stimulating activity by binding to its carrier protein.

Multiplication-stimulating activity (MSA) produced by Buffalo rat liver cells (BRL-3A) in culture is related to the somatomedin family of growth regulatory polypeptides. MSA will stimulate glucose transport and DNA synthesis in normal chicken embryo fibroblasts (CEF) at concentrations of 10-200 ng/ml. MSA found in BRL-3A-conditioned medium, like the somatomedins in serum, does not exist as the free hormone but is bound to a specific high molecular weight carrier protein. In this report we demonstrate that purified MSA carrier protein (MCP) inhibits the biological activity of MSA on CEF as measured by the stimulation of glucose transport and DNA synthesis. In addition, purified MCP competitively inhibits the binding of 125I-labeled MSA to these cells. In control experiments in which insulin was used as the mitogenic agent, MCP had no effect on these biological responses. These results indicate that the inhibitory effect of MCP is the result of specific interaction with MSA and support the hypothesis that cells may be unresponsive to somatomedins bound to their serum carrier proteins.     

Increased levels of multiplication-stimulating activity, an insulin-like growth factor, in fetal rat serum.

Multiplication-stimulating activity (MSA), purified from medium conditioned by the BRL-3A rat liver cell line, previously has been shown to be closely related to the human somatomedins or insulin-like growth factors. A radioimmunoassay was utilized to measure MSA levels in sera from fetal, maternal, and young rats. A serum somatomedin-binding protein was found to interfere in the radioimmunoassay by competing with antibody for binding 125I-labeled MSA. Therefore, prior to radioimmunoassay, sera were filtered on Sephadex G-75 in 1 M acetic acid to dissociate and separate somatomedin activity from the binding protein. Concentrations of MSA by radioimmunoassay were 20- to 100-fold higher in feta rat sera (1.8-4.4 micrograms/ml) than in maternal sera. MSA levels gradually decreased after birth, reaching maternal levels by day 25 of extrauterine life. MSA concentrations in feta rat sera also were found to be correspondingly high by a rat liver membrane radioreceptor assay and a competitive binding protein assay using rat serum somatomedin-binding protein. The findings of higher levels of MSA in fetal than in maternal rat sera and the gradual decline in MSA serum concentrations after birth are in direct contrast to total somatomedin activities measured by biosassay. Thus, MSA may function as a growth factor in the fetal rat whereas other somatomedins may play a role in stimulating growth during extrauterine life.     

Long-term treatment with 2-Br-alpha-ergocryptine in acromegaly.

Thirty acromegalic subjects underwent chronic CB154 therapy (10-20 mg daily) for periods ranging from 3 months up to 2 years. In 18 out of 21 patients, who exhibited consistent HGH reduction following acute administration of the drug, there was also during chronic treatment, a suppression of the plasma HGH levels exceeding 50% of base line values, e.g. from mean daily values between 14-197 ng/ml (mean +/- SEM = 57.8 +/- 12.4 ng/ml pre-treatment) to 2-19 ng/ml (mean 8.3 +/- 1.2 ng/ml post-treatment). In 12 of the subjects who responsed to chronic CB154 treatment, the mean daily values of HGH were below 10 ng/ml. The suppression of plasma HGH was maintained unaltered throughout the whole course of therapy. In the 9 subjects, in whom no consistent HGH decrease was evidenced with acute CB154 administration, there was accordingly a minor or no suppression of HGH values during the chronic treatment. In 13 subjects, irrespective of the degree of their GH responses, the plasma prolactin levels were constantly inhibited by CB154; instead the drug failed to modify significantly the TRH or insulin-induced GH release. These changes in the hormonal parameters were paralleled by marked clinical amelioration and improvement of some of the metabolic alterations frequently encountered in acromegaly, e.g. reduced carbohydrate tolerance, increased insulin resistance, diminished fall of plasma phosphorus after insulin, decreased urinary excretion of phosphate, hyper-hydroxyprolinuria and hyper-calciuria. Collectively, these data demonstrate that CB154 thrapy is effective in reducing HGH hyper-secretion in many acromegalic patients during long-term treatment.     

The lipolytic activity of low concentrations of insulin-like growth factors in ovine adipose tissue

Insulin-like growth factor I (IGF-I) at concentrations of 40 ng/ml is lipogenic in ovine adipose tissue slices in vitro. Neither human IGF-II (hIGF-II) or rat IGF-II (rIGF-II) [multiplication-stimulating activity (MSA)] is lipogenic at similar concentrations. However, when present at lower concentrations recombinant human IGF-I (rhIGF-I) (400 pg/ml), hIGF-II (0.4 pg/ml), and MSA (40 pg/ml) were lipolytic. As IGF-II appeared more potent than IGF-I in promoting lipolysis, this effect may be mediated via the type 2 IGF receptor. The lipolytic effect of GH may be partly due to the actions of IGFs released locally.     

Seasonal variation in plasma catecholamines and adipose tissue lipolysis in adult female green sea turtles (Chelonia mydas)

We investigated three aspects of potential interrenal regulation of reproduction in female green sea turtles, Chelonia mydas. First, seasonal trends in plasma catecholamines were examined from female C. mydas at different stages of their reproductive cycles. Second, variation in catecholamine levels during a nesting season were analysed in relation to restraint time, and ecological variables such as nesting habitat, body size, and reproductive investment. Third, catecholamine and corticosterone (CORT) induced lipolysis was investigated with adipose tissue collected from gravid green turtles, using in vitro incubations. Plasma epinephrine (EPI) was lowest in non-vitellogenic (1.55 +/- 0.26 ng/ml) and post-breeding (1.57 +/- 0.22 ng/ml) females, and highest in courting females (2.87 +/- 0.28). Concentrations of norepinephrine (NE) and EPI were relatively constant throughout a nesting season, and not significantly related to restraint time, reproductive investment or nesting habitat. In vitro concentrations of CORT (>3 ng/ml) and NE (2 ng/ml) induced significant release of glycerol after 6h of incubation. Epinephrine tended to induce an antilipolytic affect at low concentrations (0.25 ng/ml) and a net lipolytic response at higher concentrations (>1 ng/ml). Our data suggest that EPI may play a role in regulating body condition during vitellogenesis, and maintaining energy stores during prolonged aphagia during courtship and nesting in female green sea turtles. Furthermore, we provide preliminary evidence that suggests that catecholamine production may be either down regulated or de-sensitised in gravid female C. mydas.     

Insulin inhibits its own secretion from isolated,perifused human pancreatic islets

It is still a controversial question whether insulin suppresses its own secretion. We prepared pure human islets from three pancreases by collagenase digestion and density gradient purification. Aliquots of 200 islet equivalents (IE, 150-m sized-islets) were sequentially perifused at 37°C with 3.3 mmol/l glucose (3.3G, 40 min), 16.7 mmol/l glucose (16.7G, 30 min) and again 3.3G (30 min) after 24 h, 37°C culture in CMRL 1066 medium with or without the addition of either 200 or 400 U/ml human insulin in the incubation medium (6 replicates each). Insulin secretion was assessed by C-peptide (Cp) measurement in the perufusate. Without added insulin (C) and with 200 (Ins200) or 400 (Ins400) U/ml added insulin, basal Cp release was 0.12±0.03, 0.14±0.02 and 0.14±0.04 ng/ml, respectively. At 16.7G, the first-phase secretion peak (expressed as Cp value) was significantly lower with Ins200 (0.47±0.13 ng/ml,P<0.02) and Ins400 (0.68±0.15 ng/ml,P<0.05) than C (0.83±0.15 ng/ml). The second-phase secretion peak was also significantly (P<0.05) reduced with added insulin (Ins200: 0.47±0.08 ng/ml; Ins400: 0.45±0.07 ng/ml) than in its absence (C: 0.65±0.09 ng/ml). Accordingly, total Cp secretion was lower with Ins200 (10.6±2.3 ng/ml,P=0.03) and Ins400 (11.8±2.3 ng/ml) than with C (16.0±2.2 ng/ml). Thus, the addition for 24 h of either 200 or 400 U/ml insulin in the culture medium caused a significant decrease of insulin (as assessed by Cp measurement) secretion from perifused human islets, suggesting that feedback suppression of insulin release is at least in part due to a direct action of insulin on the islets.     

Endocrine, histological, and biochemical studies of adrenocorticotropin-producing islet cell carcinoma of the pancreas in childhood with characterization of proopiomelanocortin

Two 8-yr-old children, a boy and girl, are described with Cushing's syndrome secondary to ectopic ACTH-secreting pancreatic islet cell carcinomas. The girl, seen 28 yr ago, had strong presumptive evidence of ectopic ACTH production and hypercalcemia. The boy, studied recently, had strikingly elevated concentrations of plasma ACTH (1,500 pg/ml) and beta-lipotropin (beta LPH; 2,500 pg/ml) and showed no suppression of urinary 17-hydroxycorticoids or cortisol with low and high dose dexamethasone. He had increased plasma calcitonin (257 pg/ml), glucagon (442 pg/ml), lactate dehydrogenase (497 IU/liter), and alpha-fetoprotein (5,144 pg/ml). He also had hypokalemic alkalosis with elevated plasma deoxycorticosterone (70 ng/ml) and PRA (6.9 ng/ml.h) but normal plasma aldosterone (8.2 ng/dl) and 18-hydroxycorticosterone (7.6 ng/dl). Preoperative localization of the tumor was accomplished by computed tomographic scan of the abdomen with concurrent barium enema. Cell-free translation of the tumor mRNA produced authentic proopiomelanocortin of 35,000 mol wt, indicating that the ACTH and beta LPH were produced by the tumor from a common precursor. After removal of a large amount of metastatic tissue from the boy, clinical progression of the remaining tumor was monitored by measuring plasma ACTH and beta LPH. Episodic secretion of ACTH and beta LPH was demonstrated by taking frequent plasma samples while suppressing pituitary ACTH with oral dexamethasone. Chemotherapy and radiation proved ineffective in controlling the growth of his tumor.     

Diabetic coma: Serum growth hormone before and during treatment

Summary Serum growth hormone values in 37 patients with diabetic ketoacidosis were 5.4±0.8 ng/ml (S.E.M.) in males and 6.7±1.1 ng/ml in females before treatment; while in five hyperosmolar non-ketotic patients the HGH concentration was 3.9±0.5 ng/ml. One hour after insulin 90% of patients showed a rise in HGH, to a mean of 33.7±9.8 ng/ml for males and 25.5±6.0 ng/ml for females in ketoacidosis; and to 27.1±9.9 ng/ml for hyperosmolar coma patients. The rise, which was transient, was inversely correlated with pretreatment plasma glucose, the l h plasma glucose concentration and plasma urea, and directly proportional to the % fall in blood glucose after 1 h. When the ketoacidosis patients were divided into two groups according to HGH response, those with a small response had the greater disturbances of plasma glucose, blood ketone bodies, blood lactate, plasma urea, blood pH, and blood pressure, the smaller 1 h fall in blood glucose, and the higher mortality. Thus the most severely ketoacidotic patients had the poorest growth hormone response. Growth hormone is probably of little importance as an insulin antagonist in diabetic coma.Presented in part at the Spring Meeting of the British Diabetic Association, York, April 1972.     

The new steroid analog RU 486 inhibits glucocorticoid action in man

RU 486 [17 beta-hydroxy-11 beta-(4- dimethylaminophenyl )-17 alpha-(prop-1- ynyl )-estra-4,9-dien-3-one] is a new steroid analog which antagonizes glucocorticoid action at the receptor level in animals. To assess its potential antiglucocorticoid activity in man we studied the pituitary-adrenal response to RU 486 in normal men. The compound was administered at 0200 h and plasma cortisol and lipotropins (LPH) were measured hourly for 10 h. After 400 mg RU 486 significant and sustained elevation of both hormones occurred during the 0700-1200 h period: mean (+/- SE) plasma levels after placebo or RU 486 during this interval were, respectively, for cortisol (ng/ml), 63.4 +/- 8.2 and 112.7 +/- 2.9 (P less than 0.02); and for LPH (pg/ml), 34.8 +/- 11.3 and 71.6 +/- 15.4 (P less than 0.01). The 200- and 100-mg doses induced only transient cortisol and LPH increases. Administration of RU 486 (400 mg) at 1400 h induced no increase in plasma cortisol compared to placebo in the corresponding 2000 to 2400 h period. When RU 486 was administered concomitantly with dexamethasone (1 mg) at 2400 h, dose-dependent blockade of the dexamethasone-induced cortisol suppression at 0900 h was found (r = 0.62, P less than 0.01); this blockade was partial after the 100-mg dose, but complete after the 400-mg dose. Plasma LPH and ACTH showed parallel variations. We conclude that RU 486 antagonizes the negative pituitary feedback of both the nocturnal endogenous cortisol rise and exogenously administered dexamethasone. These actions are consistent with an antiglucocorticoid activity of this compound in man.     

Evaluation of propranolol-glucagon test

A propranolol-glucagon test was evaluated in 24 control normal children, 21 pituitary dwarfs, 15 patients with constitutional short stature, 2 with chromosome aberration and 4 with miscellaneous diseases. The dose of glucagon enough for the stimulation of human growth hormone (HGH) secretion is more than 20 microgram/kg of body weight. During the test in the control subjects the serum HGH level increased from 2.3 +/- 1.2 ng/ml to a maximum level of 30.0 +/- 15.1 ng/ml, when 10 mg propranolol, regardless of body weight and 30 microgram glucagon per kg of body weight are given. The dose of propranolol administered ranged from 0.2 to 1.0 mg/kg of body weight in normal children studied. Serum 11-OHCS also increased significantly from 14.5 +/- 11.2 microgram/100 ml to 30.1 +/- 15.5 microgram/100 ml (P less than 0.01). There was no difference in the maximum level of urinary total catecholamines in propranolol-glucagon test between 7 pituitary dwarfs and 7 control subjects. The mechanism of HGH response to propranolol-glucagon administration is unknown, but propranolol-glucagon administration is a sensitive and reliable provocative test for HGH secretion, since false negative response of HGH are not observed in patients with non-pituitary disease.     

Correlative study of radioreceptor assay and radioimmunoassay of serum growth hormone in children: normal children and HGH-treated pituitary dwarfs

A sensitive and reproducible radioreceptor assay (RRA) for human growth hormone (HGH) is described. It allows the evaluation of HGH concentrations as low as 2 ng/ml. It has a limited cross-reactivity with human prolactin, which does not interfere at physiological levels in children. Comparison of the results with those of radioimmunoassay (RIA) showed no discrepancies in the serum of normal children before and after stimulation tests for GH (mean RRA/RIA ratio 1.03 +/- SEM 0.04, range 0.75 to 1.65) nor in the serum from hypopituitary dwarfs during the 12 h following an im injection of 6 mg of HGH (mean RRA/RIA ratio 1.05 +/- 0.04, range 0.84 to 1.28). It is concluded that receptoractivity of HGH is parallel to its immunoreactivity in normal children and in hypopituitary patients clinical grade HGH.     

Effect of insulin and lipolytic hormones on cyclic AMP phosphodieterase activity in normal and diabetic rat adipose tissue.

Insulin has been shown to lower cyclic AMP (cAMP) levels in hormonally sensitive tissue. The mechanism by which this lowering occurs has not yet been fully defined. We studied the effects of insulin on rat adipose tissue cyclic nucleotide phosphodiestrase (PDE) in an incubation system. The adipose tissue used was from both normal animals and animals rendered diabetic by intravenous injections of streptozotocin. Rat epididymal fat pads were incubated in a Krebs-Ringer bicarbonate-4% albumin system with O, 100, 1,000 or 10,000 PU/ml insulin (INS); epinephrine (EPI) or glucagon (GLU) at several different concentrations. After 15 min of incubation, each tissue was homogenized, centrifugated, and the supernatant assayed for cAMP PDE activity using the breakdown of (3-H)cAMP. The data was used to characterize cAMP PDE into apparent high and low K-m PDE components. In the normal animals, INS increased Vmax of the low Km PDE components; 100 pU/ml INS, 30%, 1000 p1/ML INS, 40; and 10,000 pU/ml INS, 20%. In contrast, streptoxotocin diabetes lowered this Vmax by 30%. In the diabetic animals, INS also increased Vmax by 30%. In the diabetic animals, INS also increased Vmax of the low Km PDE component; 100 pU/ml INS, 30%; 1000 pU/ml INS, 50% and 10,000 pU/ml INS, 100%. Epinephrine at 1, 10, and 100 pg/ml stimulated low Km cAMP PDE activity by 67%, 73% and 44% respectively. The stimulatory effect of EPI on both the low and high Km cAMP PDE activity was neutralized by propranolol or adenosine. In comparison to EPI, GLU at very low concentrations, 10-9M, stimulated low Km cAMP PDE. These studies suggest that some of the biologic actions of insulin, an antilipolytic substance, are mediated through activation of low Km PDE. Furthermore, this enzymatic activity is lower in experimental diabetes. The stimulation of low Km PDE by lipolytic hormones may reflect a long-range protective action of these agents.     

Beta-lipotropin and cortisol responses to an intravenous infusion dexamethasone suppression test in Cushing's syndrome and obesity

An i.v. infusion dexamethasone (Dex) test was used to investigate the ACTH feedback response in 9 normal subjects, 12 obese patients, and 11 patients with Cushing's syndrome. Dex phosphate was infused iv for 4 h, starting at 1100 h (1 mg/h). Plasma concentrations of beta-lipotropin (beta LPH) and cortisol were measured every 20 min between 0900 and 1600 h, then every 2 h until midnight and at 0900 h the next day. In normal subjects and obese patients, plasma beta LPH and cortisol concentrations fell rapidly to less than 40 ng/liter and 3 micrograms/dl, respectively, at the end of Dex infusion. Subsequent values remained low through 0900 h the next day. In 7 patients with Cushing's disease, basal plasma beta LPH and cortisol concentrations declined by greater than 50% during the Dex infusion. In these patients, rapid escape from suppression occurred between 1600 and 2400 h; by 0900 h the following day, beta LPH and cortisol levels were higher than 100 ng/liter and 10 micrograms/dl, respectively. In 3 patients with adrenal tumors, beta LPH concentrations were low, and cortisol concentrations did not decline during the Dex infusion. In 1 patient with ectopic ACTH secretion, beta LPH concentrations were high and were not suppressed by the Dex infusion. We conclude that the iv infusion Dex suppression test can distinguish patients with Cushing's syndrome from normal or obese subjects and can aid in the etiological diagnosis of Cushing's syndrome.     

Antilipolytic action of insulin in abdominal adipocytes of obese subjects before and during energy restriction. Influence of adenosine deaminase

The influence of prolonged energy restriction (1250 kJ for 4 weeks) on insulin's antilipolytic action was investigated in abdominal adipocytes of obese subjects. An attempt was made to discriminate between dietary influences per se and indirect influences caused by changes in the concentration or action of adenosine. Prolonged energy restriction resulted in about a 3.5-fold increase in basal lipolytic rate which was associated with a corresponding increase in maximal response to insulin. Both these effects could be mimicked by adenosine deaminase (1.6 micrograms/ml) which increased glycerol release of adipocytes from fed donors to levels normally seen during starvation suggesting that the improvement of lipolytic responsiveness to insulin during energy restriction was an apparent one only, due to the fact that glycerol release was increased. To identify dietary influences that selectively affect insulin action the effects of insulin were compared with those of other antilipolytic agents in the presence of adenosine deaminase. Maximally effective concentrations of prostaglandin E2, clonidine and N6-phenylisopropyladenosine almost completely suppressed glycerol release before and during starvation. The extent of inhibition produced by these latter compounds was therefore related to basal activity by the same linear relationship in all experimental settings. By contrast insulin only partially depressed glycerol release and the relationships between basal activity and response to maximal concentrations of insulin were significantly different before and during starvation (P less than or equal to 0.01) in the presence of adenosine deaminase indicating that starvation selectively influences insulin action via mechanisms that are unrelated to the effects of other antilipolytic compounds. It is concluded that the main effect of energy restriction on insulin's antilipolytic action is an apparent one which is secondary increased lipolytic activity. Direct dietary effects on insulin action became apparent upon removal of endogenous adenosine. These tend to limit the maximal response to insulin and may be due to changes at the post-binding level but could also reflect an intrinsic property of insulin's antilipolytic action.     

The effects of light exposure on plasma concentrations of melatonin, LH, FSH and prolactin in women

The effects of light exposure on plasma concentrations of melatonin, LH, FSH and prolactin were studied in 11 normal cycling women during their follicular phases. Blood samples were obtained via an indwelling venous catheter every 10 min. for 2.5 hours starting at 9:30 and 21:30h. For the blood samplings taken at night, six women were kept in a dark room and were permitted to sleep. Their blood samples were obtained using a flashlight (5-10 lux) without their rest being disturbed. However, the other five women were exposed to light (3,000 lux at eye level) and awakened from 22:40 to 24:00h. Plasma melatonin concentrations in the morning decreased from 48.7 +/- 11.6 pg/ml at 9:30h to 24.7 +/- 4.0 pg/ml at 12:00h. On the other hand, plasma melatonin concentrations at night increased from 65.4 +/- 9.6 pg/ml at 21:30h to 138.2 +/- 28.6 pg/ml at 24:00h. The pulsatile LH secretion was changed from the type of "high frequency, low amplitude" in the morning to the type of "low frequency, high amplitude" at night. Nocturnal FSH concentrations were lower than diurnal ones, but nocturnal prolactin concentrations were higher than diurnal ones. Nocturnal concentrations of melatonin were suppressed 40 min. after the light exposure (from 117.4 +/- 11.4 pg/ml at 22:40h to 74.6 +/- 13.9 pg/ml at 23:20h). On the the other hand, the light exposure increased plasma prolactin concentrations from 10.9 +/- 4.1 ng/ml at 22:40h to 17.0 +/- 4.4 ng/ml at 22:50h, maintained those higher levels for 20 min. and decreased them gradually after 23:20h. With the light exposure, mean values of nocturnal LH concentrations were increased from 11.9 +/- 1.5 mIU/ml before exposure to 14.2 +/- 1.8 mIU/ml after exposure, and those of FSH were also increased from 5.9 +/- 0.4 mIU/ml to 6.3 +/- 0.4 mIU/ml. These results showed that the secretion of melatonin, as well as LH, FSH and prolactin had daily rhythms and that melatonin and prolactin showed different responses to light exposure, suggesting different control mechanisms for the secretion of those two hormones.     

Estimation of efficacy of the octreotide LAR administration in the patients with somatotropinoma

Acromegaly is caused by excessive secretion of growth hormone by a hypophyseal adenoma type of somatotropinoma. IGF-I is formed in the liver and mediates most biological actions of GH. Treatment of adenomas, which secrete GH, involves pharmacotherapy followed by surgery. Modern pharmacotherapy leaning is based on somatostatin analogues (factor restrictive secretion GH): octreotide, octreotide LAR and lanreotide. The aim of our study was estimation of efficiency of octreotide LAR in the patients with somatotropinoma prepared to neurosurgery intervention. We examined 16 patients (10 of women and 6 men) with the features of active acromegaly. In all cases the increased concentration of HGH and IGF-I were observed. The presence of pituitary adenoma in all patients was confirmed by MRI. The patients were treated with octreotide LAR monthly in dose 20 mg and 30 mg respectively. Before and after application of somatostatin analogues the concentration HGH, IGF-I, PRL in serum were marked. The concentration of GH before octreotide LAR therapy in all patients increased remarkable and ranged from 15.6 to 78.6 ng/ml, mean: 31.20 +/- 16.84 (norm: 0-10 ng/ml), also, in all cases the serum IGF-I level was increased and ranged from 451 to 1107.6 ng/ml, mean: 801.75 +/- 207.82 (norm: 100-400 ng/ml). The prolactin concentration ranged from 7.4 to 49.9 ng/ml, mean: 22.8 +/- 13.7 (norm: 2-20 ng/ml) and in 8 (50%) cases the increased of PRL concentration in serum was observed. After the administration of octreotide LAR the level of: GH [mean: 12.99 +/- 17.16 ng/ml (p < 0.001)], of IGF-I [mean 422.8 +/- 229 ng ml (p < 0.01)] statistical important decreased and prolactin in 8 with increased concentration [mean: 12.45 +/- 5.57 (p < 0.01)] were observed. Long acting somatostatin analogues--octreotide LAR is particular efficient in lowering of growth hormone and IGF-I in patients with somatotropinoma and shows efficiency in normalization of increased prolactin concentration. Because of extreme effectiveness of octreotide LAR, it should be used the routine treatment at the patients suffering from active acromegaly and preparing to neurosurgical treatment.     

Combined hyperinsulinemia and hyperglycemia, but not hyperinsulinemia alone, suppress human skeletal muscle lipolytic activity in vivo

Effects of circulating insulin and glucose concentrations on skeletal muscle and adipose tissue lipolytic activity were investigated in 10 type 1 diabetes patients with no endogenous insulin secretion. Microdialysis measurements of interstitial glycerol and determination of fractional glycerol release were carried out during standardized combinations of relative hypoinsulinemia/moderate hyperglycemia (11 mmol/liter), hyperinsulinemia/ normoglycemia (5 mmol/liter), and hyperinsulinemia/moderate hyperglycemia, respectively. Local tissue blood flow rates were measured with the (133)Xe clearance technique. In response to the change from hypo- to hyperinsulinemia, the fractional release of glycerol decreased from 159.6 +/- 17.8 to 85.1 +/- 13.7 micromol/liter (P < 0.0001) in adipose tissue, whereas it remained unchanged in skeletal muscle (44.6 +/- 6.4 vs. 36.0 +/- 7.4 micromol/liter; not significant). When hyperinsulinemia was combined with hyperglycemia, fractional glycerol release was further reduced in adipose tissue (64.5 +/- 12.2 micromol/liter; P < 0.05), and in this situation it was also markedly decreased in skeletal muscle (18.1 +/- 4.8 micromol/liter; P < 0.0001). Skeletal muscle blood flow was unaltered over the respective study periods. Adipose tissue blood flow decreased by 50% in response to hyperinsulinemia (P < 0.0005), but no further change was seen when hyperinsulinemia was combined with hyperglycemia. It is concluded that in patients with type 1 diabetes, insulin does not exert an antilipolytic effect in skeletal muscle during normoglycemia. However, in response to combined hyperinsulinemia and hyperglycemia, the lipolytic activity in skeletal muscle is restrained in a similar way as in adipose tissue. This may be explained by a glucose-mediated potentiation of the antilipolytic effectiveness of insulin.     

Growth hormone and prolactin secretion by dispersed cell cultures of a normal human pituitary: effects of thyrotrophin releasing hormone, theophylline, somatostatin, and 2-bromo-alpha-ergocryptine

Growth hormone (GH) and prolactin (Prl) secretion by a normal human pituitary in dispersed cell culture has been investigated. Prl secretion was significantly stimulated after 0.5, 1, 2 and 4 h exposure to 1, 10, 100 and 1000 ng/ml thyrotrophin releasing hormone (TRH). Maximal effects were obtained with 10 ng/ml TRH at 2 h, higher doses being less effective. GH secretion was unchanged with the exception that 1 ng/ml TRH produced a small decrease at 4 h. GH and Prl secretion was significantly inhibited by incubation with 0.01, 0.1, 1 or 10 micrograms/ml 2-bromo-alpha-ergocryptine (bromocriptine). The inhibition persisted for a further 24 h after removal of bromocriptine. Theophylline (10(-2) M) significantly increased GH and Prl secretion during a 4 h incubation and this effect was blocked by co-incubation with 10 ng/ml somatostatin (SRIF). SRIF also inhibited basal GH and Prl secretion during 4 h and removal of SRIF and incubation for at further 4 h led to a rebound in GH and Prl secretion to levels greater than control. It is concluded that cell culture techniques previously applied to the study of hormone secretion by pituitary adenomas can be equally applied to the normal human pituitary.