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Biomedical subjects

B Allolio

Publications and source records attributed to B Allolio.

At least 181 records · Page 10Linked to original sources
PubMed1986

Continuous infusion of growth hormone releasing hormone does not alter the growth hormone response to different stress stimuli.

Continuous infusion of GHRH, as well as a bolus injection of GHRH, specifically stimulates the release of GH by the anterior pituitary. However, repetitive bolus injections of GHRH result in diminished responses of GH, while a constant infusion of GHRH cannot maintain high serum GH levels. To investigate whether different GH-releasing stimuli are able further to challenge the somatotroph being exposed to continuous infusion of GHRH, we determined the GH response to insulin-induced hypoglycaemia and bicycle exercise. Six normal volunteers received a bolus of 50 micrograms GHRH or vehicle followed by a continuous infusions of GHRH 1-29 amide (1 microgram/kg/h) or vehicle for 2.5 h. GHRH bolus and infusion resulted in elevated GH levels, but GH levels fell to values not significantly different from baseline levels after 150 min, GH plasma levels rose again, however, in response to insulin hypoglycaemia and bicycle exercise after both GHRH or vehicle infusion. Thus, the somatotroph's responsiveness to GHRH remains intact to respond to stress stimuli after continuous GHRH infusion.

Adult↗
PubMed1986

Effect of adrenergic antagonism on the growth hormone, prolactin and cortisol response to a synthetic opioid agonist in man.

The intravenous administration of 250 micrograms D-Ala2-MePhe4-Met-enkephalin-O-ol (DAMME) caused a marked increase in circulating growth hormone (GH) and prolactin (PRL), and a fall in cortisol, in 14 normal subjects. Neither the alpha 1-antagonist thymoxamine, nor the alpha 2-antagonist yohimbine, significantly altered the GH and PRL responses to DAMME, suggesting that in man the growth hormone- and prolactin-releasing effects of exogenous opioids are not mediated through adrenoceptor pathways. The fall in cortisol induced by DAMME was not affected by thymoxamine, but was significantly attenuated by yohimbine, indicating that opioids may lower circulating cortisol via an interaction with noradrenergic pathways.

Adult↗
PubMed1986

FK 33-824, a met-enkephalin analog, blocks corticotropin-releasing hormone-induced adrenocorticotropin secretion in normal subjects but not in patients with Cushing's disease.

To further elucidate the site of action of opioids on the pituitary-adrenal axis, we studied the effect of D-Ala2,MePhe4,met-(O)enkephalin-ol (Sandoz, FK 33-824) on plasma ACTH and beta-endorphin immunoreactivity and serum cortisol in 7 normal subjects and 11 patients with Cushing's syndrome (Cushing's disease, n = 7; adrenal adenoma, n = 2; ectopic Cushing's syndrome, n = 2) after administration of human corticotropin-releasing hormone (hCRH). hCRH (0.1 mg; Bachem) was injected iv after pretreatment with 0.5 mg FK 33-824, im, or 0.9% saline. In normal subjects, the hCRH-induced ACTH, beta-endorphin, and cortisol increases were almost completely abolished by pretreatment with FK 33-824. Mean peak (+/- SEM) hormone concentrations were significantly reduced (ACTH, 16.7 +/- 3.5 vs. 45.3 +/- 7.8 pg/ml; beta-endorphin, 151 +/- 25 vs. 277 +/- 51 pg/ml; cortisol, 8.1 +/- 1.2 vs. 19.5 +/- 2.6 micrograms/dl; P less than 0.02), as were secretory areas (P less than 0.02). These results indicate a direct pituitary action of the synthetic met-enkephalin. In contrast, in patients with Cushing's disease, FK 33-824 did not inhibit hCRH-induced hormone release. Instead, maximum ACTH and beta-endorphin concentrations were slightly but not significantly higher after the administration of FK 33-824 (ACTH, 292 +/- 143 vs. 131 +/- 32 pg/ml; beta-endorphin, 2409 +/- 763 vs. 1921 +/- 600 pg/ml). These findings indicate a defect in inhibitory opiodergic control of ACTH secretion in patients with Cushing's disease, which may contribute to the pathological ACTH hypersecretion. In patients with Cushing's syndrome due to an adrenal adenoma or ectopic ACTH secretion, neither hCRH nor FK 33-824 altered hormone concentrations.

Adolescent↗
PubMed1985

Effects of high-dose and low-dose naloxone on plasma ACTH in patients with ACTH hypersecretion.

The effect of a high (5.4 mg/h) and a low (0.8 mg/h) dose of naloxone (i.v. over a period of 90 min) on ACTH secretion was compared with placebo in patients with Addison's disease, congenital adrenal hyperplasia, Cushing's disease or Nelson's syndrome. In seven patients with primary adrenal insufficiency the high dose of naloxone provoked a significant increase of plasma ACTH concentrations (P less than 0.02) whereas the low dose of naloxone failed to influence ACTH secretion. In six patients with ACTH dependent Cushing's disease or Nelson's syndrome both doses failed to alter plasma ACTH levels. These results support the concept of inhibitory delta- or kappa-opiate receptors in the regulation of ACTH secretion. In patients with Cushing's disease or Nelson's syndrome ACTH secretion is insensitive to naloxone, presumably because of an autonomous pituitary adenoma or hypothalamic derangement.

Adrenal Gland Diseases↗
PubMed1985

Effect of a single bolus of etomidate upon eight major corticosteroid hormones and plasma ACTH.

In a prospective controlled trial we investigated the effect of an induction dose of etomidate (0.26 mg/kg i.v.) on plasma ACTH, progesterone, 17 alpha OH-progesterone, 11-deoxycortisol, cortisol, cortisone, corticosterone, 11-deoxycorticosterone, and aldosterone in seven males undergoing general anaesthesia. Seven other male patients receiving thiopentone at induction (5.0 mg/kg i.v.) served as controls. Plasma ACTH concentrations rose higher in the etomidate group (346 +/- 124 vs. 117 +/- 74 pg/ml, mean +/- SEM), but the difference was not significant. After etomidate we found a clear suppression of plasma cortisol (P less than 0.01), cortisone (P less than 0.01), corticosterone (P less than 0.01), and aldosterone (P less than 0.05) compared to corticosteroid levels after induction with thiopentone. Plasma 11-deoxycortisol and 11-deoxycorticosterone concentrations were grossly elevated 210 min after etomidate (91 +/- 28 nmol/l and 7.04 +/- 0.47 nmol/l, respectively, P less than 0.01) demonstrating inhibition of 11 beta-hydroxylation of both glucocorticoid and mineralocorticoid intermediates. In contrast, no significant difference in plasma progesterone and 17 alpha-OH-progesterone levels was found between the two groups indicating that the cholesterol-side-chain cleavage enzyme is less sensitive to etomidate than 11 beta-hydroxylase. Our results suggest that after induction of anaesthesia with a single bolus of etomidate, inhibition of other enzymes in the corticosteroid-synthetic pathway (e.g. cholesterol-side-chain cleavage enzyme) is of little clinical relevance.

17-alpha-Hydroxyprogesterone↗
PubMed1984

Adrenocortical suppression by a single induction dose of etomidate.

In a prospective controlled trial we studied the effect of a single induction dose of etomidate or thiopentone on the adrenocortical function in 29 patients undergoing elective surgery. During anesthesia and in the recovery period serum cortisol rose significantly in the thiopentone group only. In contrast, after induction with etomidate serum cortisol decreased and remained below the starting values throughout the study period (5 h). The differences between the two groups were significant at 120, 150, 180, 210, and 240 min after induction (p less than 0.05). Moreover, plasma ACTH increased significantly more after etomidate than after thiopentone (p less than 0.02) indicating relative unresponsiveness of the adrenal cortex to stimulation by endogenous ACTH. We conclude that a single i.v. bolus of etomidate (0.26 mg/kg) leads to significant adrenal insufficiency in patients without preexisting endocrine abnormalities.

Adolescent↗
PubMed1984

Adrenocorticotropin, calcitonin, and antidiuretic hormone as tumor markers in patients with bronchogenic carcinoma of various histological types.

We measured basal and dexamethasone-suppressed plasma ACTH in 246 patients with bronchogenic carcinoma (105 with small-cell carcinoma); in 138 of these patients (67 with small-cell carcinoma) basal and pentagastrin-stimulated serum calcitonin was also determined. In addition, in a subgroup of 120 patients (58 with small-cell carcinoma) plasma ADH with reference to plasma osmolality was also assayed. Non-suppressible plasma ACTH was found in 45% of patients with small-cell carcinoma but only in isolated cases of large-cell carcinoma, adenocarcinoma, and squamous-cell carcinoma. Serum calcitonin was increased in 28% of patients with small-cell carcinoma but only in few patients with other tumor types. Stimulation of calcitonin by pentagastrin was ineffective. Plasma ADH was inappropriately high in 47% of patients with small-cell carcinoma. Strikingly high also was the incidence of increased ADH concentrations in patients with large-cell (40%), adenocarcinoma (46%), and squamous-cell carcinoma (29%). By measuring plasma ACTH after dexamethasone suppression and ADH with reference to osmolality, the sensitivity of these tumor markers in detecting pathological hormone secretion is markedly increased. In small-cell carcinoma the simultaneous measurement of ACTH, ADH, and calcitonin gives a high yield of positive results (74%), indicating that this set of tumor markers is a promising aid in diagnosis and therapy control.

Adenocarcinoma↗
PubMed1984

Development of a non-extracted 'two-site' immunoradiometric assay for corticotropin utilizing extreme amino- and carboxy-terminally directed antibodies.

The development of a 'two-site' immunoradiometric assay (i.r.m.a.) for the direct estimation of human corticotropin-(1-39)-peptide in plasma is described. The assay is based on the simultaneous addition of 125I-labelled sheep anti-(N-terminal corticotropin) IgG (immunoglobulin G) antibodies and rabbit anti-(C-terminal corticotropin) antiserum to standards and unknowns (0.5 ml) followed by 18h incubation. The use of solid-phase reagents was avoided in order to minimize non-specific effects and the time required for reactants to reach equilibrium. Instead, the separation of corticotropin-bound from free labelled antibody is achieved by the addition of sheep anti-(rabbit IgG) antiserum, which precipitates bound labelled antibody by complex-formation with rabbit anti-corticotropin antibodies, which are also hormone-bound. Several 125I-labelled sheep anti-(N-terminal corticotropin) IgG preparations were assessed in the i.r.m.a. Although each was derived from antisera raised to a thyroglobulin conjugate of synthetic corticotropin-(1-24)-peptide (Synacthen), purification of immunoglobulins before iodination by selective immunoadsorption resulted in preparations with distinct specificities which demonstrated marked differences in binding to intact human corticotropin-(1-39)-peptide. These preparations are compared in combination with two rabbit anti-(C-terminal corticotropin) antisera. A 'two-site' assay based on the use of 125I-labelled sheep anti-[ corticotropin-(2-16)-peptide] IgG and rabbit anti-[corticotropin-(34-39)-peptide] antiserum was optimized, since steric inhibition of antibody binding was avoided with this combination and because the measurement of only intact human corticotropin-(1-39)-peptide and not fragments was assured by the use of terminal antibodies. This i.r.m.a. is characterized by rapid equilibration of reactants, a wide 'operating range' (the precision of dose estimates was less than 4% over the range 30-2200 pg/ml) and high sensitivity [8 pg of corticotropin/ml (95% confidence interval 3.7-12.0) (4 pg minimal detectable mass) can be detected directly in plasma].

Adrenocorticotropic Hormone↗
PubMed1983

[Antidigoxin Fab-fragments in suicidal digoxin poisoning. Successful treatment of recurrent ventricular fibrillation].

A 49-year-old woman took about 12.5 mg digoxin with suicidal intent. Severe arrhythmias, including recurrent ventricular fibrillation, occurred. Sheep Fab fragments of digoxin-specific antibodies were administered i. v. at a dose of 480 mg. Serum free-digoxin concentration fell within half an hour to 0, with simultaneous rise of total digoxin from 13 micrograms/l to a maximum of 176 micrograms/l after 2 hours. At the same time there was marked improvement in the clinical condition with restoration of a stable sinus rhythm. There were no side effects to the Fab fragment administration.

Antibodies↗
PubMed1983

Raised plasma metenkephalin in patients who habitually mutilate themselves.

Mean plasma metenkephalin concentration was significantly higher in ten patients who habitually mutilated themselves than in matched, healthy controls. No differences were found in corticotropin, N-lipotropin or C-lipotropin (beta-endorphin). Plasma metenkephalin was raised only in the five patients receiving hospital treatment because of their behaviour disorder. It was not raised in those patients sufficiently well to have been discharged from hospital.

Adult↗
PubMed1983

Effect of meclastine, a selective H1 receptor antagonist, upon ACTH release.

To elucidate further the role of histamine in the control of ACTH secretion we investigated the effect of the selective H1 receptor antagonist meclastine on the ACTH response to insulin hypoglycaemia and to metyrapone-induced hypocortisolaemia in normal subjects. Intravenous meclastine (4.8 mg/90 min) significantly inhibited the hypoglycaemia-induced ACTH and cortisol increase whereas serum GH and PRL concentrations were unaffected. Orally administered meclastine (3 X 2 mg) also reduced the ACTH feedback response to cortisol deficiency in a modified metyrapone test, compared to a placebo. Our findings support the concept of an excitatory influence of histamine upon ACTH secretion via H1 receptors, possibly by stimulation of CRF release.

Adolescent↗
PubMed1982

Effects of a met-enkephalin analog on adrenocorticotropin (ACTH), growth hormone, and prolactin in patients with ACTH hypersecretion.

The effect of D-Ala2, MePhe4, Met-(0)enkephalinol (Sandoz FK 33-824; 0.5 mg, im) on pituitary hormone secretion was studied in 11 patients with Addison's disease and 11 patients with ACTH-dependent Cushing's disease. In patients with Addison's disease, a pronounced fall of plasma ACTH levels was observed (P less than 0.005). The ACTH response to FK 33--824 was partially reversed by naloxone (4 mg, iv). In patients with Cushing's disease, no unequivocal decrease in either ACTH or cortisol was seen. Moreover, FK 33--824 failed to influence the vasopressin-induced ACTH increase in 5 patients with Cushing's disease. In patients with cortisol deficiency due to either Addison's disease or bilateral adrenalectomy for Cushing's disease, FK 33--824 led to increases in PRL and GH similar to those described in normal subjects. However, in the presence of longstanding hypercortisolism, the PRL increase was significantly diminished, and the GH response to FK 33--824 was completely abolished. Our results suggest that in Addison's disease ACTH release is influenced by inhibitory opiate receptors. In patients with Cushing's disease, ACTH secretion is insensitive to FK 33-284, presumably because of an autonomous pituitary adenoma or hypothalamic derangement. The impairment of the PRL and GH responses to FK 33--824 in Cushing's syndrome seems to reflect a direct action of the elevated cortisol level, for it is not seen after bilateral adrenalectomy.

Addison Disease↗