A step towards cinacalcet testing for the diagnosis of primary hyperparathyroidism: comparison with the standardized intravenous calcium loading. A pilot study.

OBJECTIVE: A calcium load to suppress parathyroid hormone (PTH) secretion can help to perform the diagnosis in some case of primary hyperparathyroidism (PHPT) with atypical presentation. A similar test with calcimimetic, which avoids hypercalcaemia, would be of interest. Our proof of concept study was conducted to compare firstly the results of a single-dose cinacalcet testing with those of the standardized short-time calcium load in healthy control (HC) and secondly the results of the single-dose cinacalcet testing in HC and in PHPT. METHODS: Twelve HCs received in a random order, at a 2-week interval, either 0·33 mmol/kg calcium gluconate intravenously for 3 h, or a single oral dose of 30 mg or 60 mg cinacalcet. Twelve PHPTs received 30 mg cinacalcet and twelve other PHPTs 60 mg cinacalcet orally. Calcaemia and serum PTH levels were measured basally and then hourly for 6 h. RESULTS: In HC, plasma calcium did not significantly change after cinacalcet intake, whereas calcaemia rose up to 3·47 ± 0·05 mmol/l (mean ± SEM) at the end of the calcium load. PTH dropped from basal level to a similar extend (≥80%) with 60 mg cinacalcet and calcium load, whereas the decrease was significantly lesser (P < 0·01) with 30 mg cinacalcet. In PHPT, serum PTH levels dropped by 44·8 ± 6·9% and 58·2 ± 5·3% 1 h after the respective intake of 30 and 60 mg cinacalcet. One hour after the oral intake of 60 mg cinacalcet, serum PTH levels were <8 ng/l in HC and ≥8 ng/l in PHPT. CONCLUSION: Sixty milligrams of cinacalcet provides similar results as the standardized calcium load test; PHPT patients have a lower response to 60 mg cinacalcet than HC.

Study of the involvement of pancreastatin in the physiopathology of diabetes mellitus associated with nonsecreting pituitary adenomas.

Pancreastatin, derived from chromogranin A, inhibits insulin and stimulates glucagon secretion in rodents. Immunohistochemistry localised pancreastatin in human pancreatic islet cells and gonadotroph pituitary cells. Nonsecreting pituitary adenomas, frequently associated with diabetes mellitus, arise quasi-constantly from gonadotroph cells. We evaluated the possible involvement of pancreastatin in the physiopathology of diabetes mellitus associated with nonsecreting pituitary adenomas. Plasma pancreastatin levels were measured by radioimmunoassay in 5 groups of subjects: 10 patients with nonsecreting pituitary adenomas associated with diabetes mellitus (group I), 10 patients with nonsecreting pituitary adenomas without diabetes (Group II), 10 patients with ACTH or GH-secreting pituitary adenomas and diabetes mellitus (Group III), 10 diabetic patients without pituitary adenomas (Group IV), and 10 healthy controls (Group V). Kidney and liver functions were normal in all of them and no patient was treated with a proton pump inhibitor. All pituitary adenomas were trans-sphenoidally removed. Immunohistochemistry against pancreastatin was performed in 5 patients of each of the 3 groups of pituitary adenomas. Plasma pancreastatin levels were not different between the different groups: 182±46 pg/ml (Group I), 195±57 pg/ml (Group II), 239±42 pg/ml (Group III), 134±31 pg/ml, (Group IV), and 122±29 pg/ml (Group V). In contrast, they were significantly (p<0.05) higher before (391±65 pg/ml) than after trans-sphenoidal surgery (149±18 pg/ml) without post-surgical change in diabetes. An immunostaining against pancreastatin was found in a majority of pituitary adenomas, associated or not with diabetes mellitus. These results argue against a role of pancreastatin in the pathogenesis of diabetes mellitus associated with nonsecreting pituitary adenomas.

mRNA cap binding proteins: effects on abscisic acid signal transduction, mRNA processing, and microarray analyses.

The plant hormone abscisic acid (ABA) intricately regulates a multitude of processes during plant growth and development. Recent studies have established a connection between genes participating in various steps of cellular RNA metabolism and the ABA signal transduction machinery. In this chapter we focus on the plant nuclear mRNA cap binding proteins, CBP20 and CBP80. We summarize and report recent findings on their effects on cellular signal transduction networks and mRNA processing events. ABA hypersensitive 1 (abh1) harbors a gene disruption in the Arabidopsis CBP80 gene. Loss-of-function mutation of ABH1 can also result in an early flowering phenotype in the Arabidopsis accession C24. abh1 revealed noncoding cis-natural antisense transcripts (cis-NATs) at the CONSTANS locus in wild-type plants with elevated cis-NAT expression in the mutant. abh1 also revealed an influence on the splicing of the MADS box transcription factor Flowering Locus C pre-mRNA, which may result in the regulation of flowering time. Furthermore, new experiments analyzing complementation of cpb20 with site-directed cpb20 mutants provide evidence that the CAP binding activity of CBP20 is essential for the observed cbp-associated phenotypes. In conclusion, mutants in genes participating in RNA processing provide excellent tools to uncover novel molecular mechanisms for the regulation of RNA metabolism and of signal transduction networks in wild-type plants.

Ectopic expression of serotonin7 receptors in an adrenocortical carcinoma co-secreting renin and cortisol.

Abnormal expression of membrane receptors has been previously described in benign adrenocortical neoplasms causing Cushing's syndrome. In particular, we have observed that, in some adreno corticotropic hormone (ACTH)-independent macronodular adrenal hyperplasia tissues, cortisol secretion is controlled by ectopic serotonin(7) (5-HT(7)) receptors. The objective of the present study was to investigate in vitro the effect of serotonin (5-hydroxy tryptamine; 5-HT) on cortisol and renin production by a left adrenocortical carcinoma removed from a 48-year-old female patient with severe Cushing's syndrome and elevated plasma renin levels. Tumor explants were obtained at surgery and processed for immunohistochemistry, in situ hybridization and cell culture studies. 5-HT-like immunoreactivity was observed in mast cells and steroidogenic cells disseminated in the tissue. 5-HT stimulated cortisol release by cultured cells. The stimulatory effect of 5-HT on cortisol secretion was suppressed by the 5-HT(7) receptor antagonist SB269970. In addition, immunohistochemistry showed the occurrence of 5-HT(7) receptor-like immunoreactivity in carcinoma cells. mRNAs encoding renin as well as renin-like immunoreactivity were detected in endothelial and tumor cells. Cell incubation studies revealed that the adrenocortical tissue also released renin. Renin production was inhibited by 5-HT but was not influenced by ACTH and angiotensin II (Ang II). In conclusion, the present report provides the first demonstration of ectopic serotonin receptors, i.e. 5-HT(7) receptors, in an adrenocortical carcinoma. Our results also indicate that 5-HT can influence the secretory activity of malignant adrenocortical tumors in an autocrine/paracrine manner. The effects of 5-HT on adrenocortical tumor cells included a paradoxical inhibitory action on renin production and a stimulatory action on cortisol secretion involving 5-HT(7) receptors.

Weight loss and quality of life after bariatric surgery: a study of 200 patients after vertical gastroplasty or adjustable gastric banding.

BACKGROUND AND OBJECTIVES: Long term evaluation of bariatric surgery must include quality of life measurement. METHODS: Quality of life (QoL) was evaluated using the original Moorehead-Ardelt questionnaire for 200 patients operated for massive obesity in a single centre between 1994 and 2003. QoL and physical data were obtained by retrospective mail questionnaire. Surgical procedures were vertical-banded gastroplasty according to Mason (VBGM) and adjustable gastric banding (AGB) in 61 and 39% of patients, respectively. The aim of the study was to assess the nutritional outcome and QoL according to the procedure. RESULTS: Overall, the body mass index (BMI) decreased from 50+/-8 kg/m(2) before surgery to 35.2+/-7.5 kg/m(2) at the time of the questionnaire. The percentage of weight loss was 28.8+/-12.2%. In the group treated with VBGM, the mean initial weight (P=0.003) and the percentage of weight loss (P<0.001) were significantly higher, and the QoL was better (P=0.003) than in the group treated with AGB. On the basis of the time spent since surgery, a regular weight loss was observed during the first 5 years, whereas weight subsequently increased over the five following years. Similarly, the total QoL score gradually improved during the first 5 years and worsened thereafter. However, it remained better than before surgery. A linear regression analysis showed a positive correlation between the percentage of weight loss and the QoL score (P<0.001). CONCLUSIONS: This study suggests that the bariatric surgery, particularly the VBGM technique, improved the QoL of obese patients, at least in the first 5 years following surgery.

Simultaneous suprasellar and pineal germ cell tumors in five late stage adolescents: endocrinological studies and prolonged follow-up.

Primary germ cell tumors (PGCT) of the central nervous system usually develop in the third ventricle area, and most frequently in the pineal region. The suprasellar region is the second preferential site for development of these tumors which are rarely simultaneously present in these two sites. We report five new cases of PGCT with pineal and suprasellar localizations, which appeared in late puberty in four boys and one girl aged 17-19 years. The clinical picture associated signs of intracranial hypertension, convergence and verticality palsies, diabetes insipidus and pituitary deficiency. Encephalic MRI revealed a double localization. Endocrine tests revealed a particular pattern associating central diabetes insipidus and a hypothalamic-pituitary disconnection syndrome. Following identification of the pathological type of lesions via a neurosurgical approach, treatment was based on a combined method using chemotherapy, radiotherapy and hormone replacement. Based on this treatment, prolonged remissions were obtained with a good quality of life.

The pituitary V3 vasopressin receptor and the corticotroph phenotype in ectopic ACTH syndrome.

Ectopic ACTH secretion occurs in highly differentiated and rather indolent tumors like bronchial carcinoids or, in contrast, in various types of aggressive and poorly differentiated neuroendocrine tumors. We explored this phenomenon using the recently cloned human pituitary V3 vasopressin receptor as an alternate molecular marker of the corticotroph phenotype. Expression of V3 receptor, corticotrophin releasing hormone (CRH) receptor, and proopiomelanocortin (POMC) genes was examined in tumors of pituitary and nonpituitary origin. A comparative RT-PCR approach revealed signals for both V3 receptor and CHR receptor mRNAs in 17 of 18 ACTH-secreting pituitary adenomas, and 6 of 6 normal pituitaries; in six growth hormone- or prolactin-secreting adenomas, a very faint V3 receptor signal was observed in three cases, and CRH receptor signal was undetected in all. Six of eight bronchial carcinoids responsible for the ectopic ACTH syndrome had both POMC and V3 receptor signals as high as those in ACTH-secreting pituitary adenomas; in contrast, no POMC signal and only a very faint V3 receptor signal were detected in six of eight nonsecreting bronchial carcinoids. Northern blot analysis showed V3 receptor mRNA of identical size in ACTH-secreting bronchial carcinoids and pituitary tumors. Other types of nonpituitary tumors responsible for ectopic ACTH syndrome presented much lower levels of both POMC and V3 receptor gene expression than those found in ACTH-secreting bronchial carcinoids. In contrast with the V3 receptor, CRH receptor mRNA was detected in the majority of neuroendocrine tumors irrespective of their POMC status. These results show that expression of the V3 receptor gene participates in the corticotroph phenotype. Its striking association with ACTH-secreting bronchial carcinoids defines a subset of nonpituitary tumors in which ectopic POMC gene expression is but one aspect of a wider process of corticotroph cell differentiation, and opens new possibilities of pharmacological investigations and even manipulations of this peculiar ACTH hypersecretory syndrome.

Gamma knife radiosurgery is a successful adjunctive treatment in Cushing's disease.

OBJECTIVE: Though transsphenoidal surgery remains the first-line treatment of Cushing's disease, recurrence occurs frequently. Conventional radiotherapy and anticortisolic drugs both have adverse effects. Stereotactic radiosurgery needs to be evaluated more precisely. The aim of this study was to determine long-term hormonal effects and tolerance of gamma knife (GK) radiosurgery in Cushing's disease. DESIGN: Forty patients with Cushing's disease treated by GK were prospectively studied over a decade, with a mean follow-up of 54.7 months. Eleven of them were treated with GK as a primary treatment. METHODS: Radiosurgery was performed at the Department of Functional Neurosurgery of Marseille, France, using the Leksell Gamma Unit B and C models. Median margin dose was 29.5 Gy. Patients were considered in remission if they had normalized 24-h free urinary cortisol and suppression of plasma cortisol after low-dose dexamethasone suppression test. RESULTS: Seventeen patients (42.5%) were in remission after a mean of 22 months (range 12-48 months). The two groups did not differ in terms of initial hormonal levels. Target volume was significantly higher in uncured than in remission group (909.8 vs 443 mm(3), P = 0.038). We found a significant difference between patients who were on or off anticortisolic drugs at the time of GK (20 vs 48% patients in remission respectively, P = 0.02). CONCLUSION: With 42% of patients in remission after a median follow-up of 54 months, GK stereotactic radiosurgery, especially as an adjunctive treatment to surgery, may represent an alternative to other therapeutic options in view of their adverse effects.

Luteinizing hormone pulsatility in patients with major ovarian hyperandrogenism.

Hyperandrogenism and ovulatory dysfunction are common in women with either polycystic ovary (PCOS) or ovarian virilizing tumor. However, contrasting with the numerous studies that have extensively described gonadotropin secretory abnormalities, principally increased LH pulse amplitude and frequency, few studies have concerned gonadotropin secretion in patients with ovarian virilizing tumors; low gonadotropin levels have occasionally been reported, but never extensively studied. The goal of the present study was to further evaluate the pulsatility of LH secretion in women with ovarian virilizing tumor compared with that of PCOS patients. Eighteen women with major hyperandrogenism (plasma testosterone level >1.2 ng/ml) were studied (5 women with ovarian virilizing tumor, 13 women with PCOS, and 10 control women). Mean plasma LH level, LH pulse number and amplitude were dramatically low in patients with ovarian tumors when compared to both PCOS (p<0.001) and controls (p<0.001). In case of major hyperandrogenism, LH pulse pattern differs markedly between women with ovarian virilizing tumor or PCOS, suggesting different mechanisms of hypothalamic or pituitary feedback.

MEN1 disease occurring before 21 years old: a 160-patient cohort study from the Groupe d'étude des Tumeurs Endocrines.

CONTEXT: Multiple endocrine neoplasia Type-1 (MEN1) in young patients is only described by case reports. OBJECTIVE: To improve the knowledge of MEN1 natural history before 21 years old. METHODS: Obtain a description of the first symptoms occurring before 21 years old (clinical symptoms, biological or imaging abnormalities), surgical outcomes related to MEN1 Neuro Endocrine Tumors (NETs) occurring in a group of 160 patients extracted from the "Groupe d'étude des Tumeurs Endocrines" MEN1 cohort. RESULTS: The first symptoms were related to hyperparathyroidism in 122 cases (75%), pituitary adenoma in 55 cases (34%), nonsecreting pancreatic tumor (NSPT) in 14 cases (9%), insulinoma in 20 cases (12%), gastrinoma in three cases (2%), malignant adrenal tumors in 2 cases (1%), and malignant thymic-NET in one case (1%). Hyperparathyrodism was the first lesion in 90 cases (56%). The first symptoms occurred before 10 years old in 22 cases (14%) and before 5 years old in five cases (3%). Surgery was performed before age 21 in 66 patients (41%) with a total of 74 operations: pituitary adenoma (n = 9, 16%), hyperparathyroidism (n = 38, 31%), gastrinoma (n = 1, 33%), NSPT (n = 5, 36%), and all cases of insulinoma, adrenal tumors, and thymic-NET. One patient died before age 21 due to a thymic-NET. Overall, lesions were malignant in four cases. CONCLUSIONS: Various MEN1 lesions occurred frequently before 21 years old, but mainly after 10 years of age. Rare, aggressive tumors may develop at any age. Hyperparathyroidism was the most frequently encountered lesion but was not always the first biological or clinical abnormality to appear during the course of MEN1.

Unraveling the intrafamilial correlations and heritability of tumor types in MEN1: a Groupe d'étude des Tumeurs Endocrines study.

BACKGROUND: MEN1, which is secondary to the mutation of the MEN1 gene, is a rare autosomal-dominant disease that predisposes mutation carriers to endocrine tumors. Most studies demonstrated the absence of direct genotype-phenotype correlations. The existence of a higher risk of death in the Groupe d'étude des Tumeurs Endocrines-cohort associated with a mutation in the JunD interacting domain suggests heterogeneity across families in disease expressivity. This study aims to assess the existence of modifying genetic factors by estimating the intrafamilial correlations and heritability of the six main tumor types in MEN1. METHODS: The study included 797 patients from 265 kindred and studied seven phenotypic criteria: parathyroid and pancreatic neuroendocrine tumors (NETs) and pituitary, adrenal, bronchial, and thymic (thNET) tumors and the presence of metastasis. Intrafamilial correlations and heritability estimates were calculated from family tree data using specific validated statistical analysis software. RESULTS: Intrafamilial correlations were significant and decreased along parental degrees distance for pituitary, adrenal and thNETs. The heritability of these three tumor types was consistently strong and significant with 64% (s.e.m.=0.13; P<0.001) for pituitary tumor, 65% (s.e.m.=0.21; P<0.001) for adrenal tumors, and 97% (s.e.m.=0.41; P=0.006) for thNETs. CONCLUSION: The present study shows the existence of modifying genetic factors for thymus, adrenal, and pituitary MEN1 tumor types. The identification of at-risk subgroups of individuals within cohorts is the first step toward personalization of care. Next generation sequencing on this subset of tumors will help identify the molecular basis of MEN1 variable genetic expressivity.

Plasma lipotropin increase in man after growth hormone administration. Comparison between extractive and biosynthetic hormones.

The action of human growth hormone (hGH) on plasma lipotropins (beta-and gamma-LPH) in 15 GH deficient patients was studied by comparing the effects induced by the acute administration of the extracted and biosynthetic molecules. The purified extracted preparation (6 mg/m2 im) induced a dramatic rise in plasma LPH: basal (49 +/- 12 pg/ml (mean +/- SEM); peak 1,658 +/- 262 pg/ml. The same dose of biosynthetic methionyl-hGH (met-hGH) induced no significant change in plasma LPH. Both preparations caused identical plasma GH increases. Six different commercially available extracted hGH preparations (Choay, France; Serono, Italy; France Hypophyse, France; Kabi, Sweden; Nordisk, Denmark; International Standard, Great Britain) all showed definite cross-reactivity in the LPH radioimmunoasay, varying from 0.1 to 1.0%, on a weight basis. No cross reactivity was found with met-hGH (less than 0.0001%). On gel exclusion chromatography, the LPH immunoreactivity of the purified preparations was dissociated from the GH immunoreactivity and eluted at the position of beta-and gamma-LPH. These data show that extracted hGH preparations are all contaminated with LPH and raise the question of the possible consequences of chronically elevated plasma LPH in treated patients. The use of biosynthetic met-hGH should prevent this occurence.

True hermaphroditism: from female to male endocrine status.

True hermaphroditism was revealed by monthly intrascrotal bleeding in a 21-yr-old subject of male phenotype who had undergone surgical treatment for gonadal ectopy at the age of 7 yr. The presence of an ovary was demonstrated by the endocrine profile of an ovulatory menstrual cycle. Evidence for the presence of a testis was provided by a plasma testosterone increase after hCG administration (5000 IU/day for 3 days) and its spontaneous response to an endogenous preovulatory LH peak. Further endocrine studies revealed that both gonads were stimulated by endogenous gonadotropins. At surgery, a hemiuterus and an ovary with corpus luteum were found in the left hemiscrotum, and a testis and epididymis were found in the right hemiscrotum. After removal of the ovary, the subject passed from a predominantly female to a male endocrine status, which suggests that the endocrine secretion of the testis was inhibited by the negative feedback effect of ovarian steroids on gonadotropin secretion.

Production and metabolism of serotonin (5-HT) by the human adrenal cortex: paracrine stimulation of aldosterone secretion by 5-HT.

In the human adrenal cortex, serotonin (5-HT) is contained in mast-like cells, and we have shown that 5-HT stimulates aldosterone secretion, suggesting that 5-HT may control glomerulosa cells through a paracrine mechanism. Concurrently, the presence of 5-hydroxyindolacetic acid in human adrenocortical extracts indicates that 5-HT may be metabolized after local release by mast cells. The aim of the present study was to investigate in vitro the production and metabolism of 5-HT by the human adrenal cortex. Perifused adrenal slices released spontaneously detectable amounts of 5-HT (0.74 +/- 0.38 fmol/mg wet tissue.min). The mast cell-depleting drug compound 48/80 induced a burst of 5-HT secretion followed by a gradual increase in aldosterone production. Administration of the specific 5-HT(4) receptor antagonist GR 113808 (10(-6) M) did not affect compound 48/80-induced 5-HT release but abolished the stimulatory effect of compound 48/80 on aldosterone secretion, indicating that 5-HT released locally is responsible for a paracrine control of steroidogenesis. Incubation of cells from the human adrenal cortex with 5-HT (10(-5) M) provoked the formation of the 5-HT metabolite 5-hydroxytryptophol. The type A monoamine oxidase (MAO) inhibitor clorgyline (10(-6) M) suppressed the metabolism of 5-HT into 5-hydroxytryptophol. Immunocytochemical staining of cultured cells revealed the presence of a subpopulation of MAO-A-positive cells. Double labeling with an antiserum against chromogranin A showed that MAO-A was actually contained in chromaffin cells. Similarly, immunohistochemical staining of adrenal slices showed that MAO-A was expressed in chromaffin cells located both in the medulla and in intracortical rays. In conclusion, the present study shows that, in the human adrenal cortex, 5-HT, released by mast-cells, may stimulate aldosterone secretion in a paracrine manner. Our data also indicate that 5-HT is metabolized by MAO-A located in intracortical chromaffin cells.

Testicular steroidogenesis in adult men with human chorionic gonadotropin-producing tumors.

There are few critical studies on plasma testosterone (T) and 17 beta-estradiol (E2) levels in men with hCG-producing tumors, and the results are contradictory. Plasma E2 levels are most often elevated, whereas plasma T values are high or in the normal range. We studied the plasma levels of such steroids and of delta 4 and delta 5 T precursors in adult men with intact hCG-producing tumors to evaluate the relationship between hCG and steroid hormone levels or steroidogenic enzyme activities. Ten adult men with hCG-producing tumors and 25 normal adult men were investigated. Seven men with testicular tumors were studied before and after hemicastration. The 2 patients with extratesticular tumors were investigated before and during chemotherapy. The remaining patient was studied every 2 months for 1 yr during the spontaneous course of the disease. Plasma progesterone (P), 17 alpha-hydroxyprogesterone (17-OHP), androstenedione (A), 17-hydroxy-delta 5-pregnenolone (17-OH delta 5-P), dehydroepiandrosterone (DHEA), T, E2, and hCG were measured, and ratios of steroid levels were also calculated. In patients with increased hCG values (i.e. > 5 IU/L), the mean plasma P, 17-OHP, A, 17-OH delta 5-P, DHEA, T, and E2 levels were higher (P < 0.01 at least) than those in patients whose hCG values were normalized or in controls. The patterns of these steroids were very different according to plasma hCG levels. Indeed, for hCG levels between more than 5 and 3.5 x 10(3) IU/L, positive correlations (P < 0.05 at least) were found between hCG levels and delta 4 T precursor, delta 5 T precursor, T, or E2 values. Conversely, for hCG values greater than 3.5 x 10(3) IU/L, hCG levels were negatively correlated (P < 0.05 at least) to all steroid values. Furthermore, in patients with increased hCG levels, the mean plasma P to 17-OHP ratio, 17-OHP to A ratio, A to T ratio, 17-OHP to T ratio, and 17-OH delta 5-P to DHEA ratio were similar to those in patients with normalized hCG values or in controls. In contrast, in patients with increased hCG levels, the mean plasma T to E2 ratio value was lower (P < 0.001) than that in patients with normalized hCG levels or in controls.(ABSTRACT TRUNCATED AT 400 WORDS)

The serotonin-4 receptor agonist cisapride and angiotensin-II exert additive effects on aldosterone secretion in normal man.

In animals and man, serotonin (5-HT) exerts a direct stimulatory action on adrenocortical cells through activation of 5-HT4 receptors. In rats, 5-HT also potentiates the stimulatory effect of angiotensin-II (Ang II) on aldosterone secretion. The aim of the present study was to investigate the effect of concomitant administration of the 5-HT4 receptor agonist, cisapride, and Ang II on aldosterone secretion in normal human subjects. Eight healthy male volunteers pretreated with dexamethasone received, at 1-week intervals in random order and simple blind fashion, the following treatments: 1) a single oral dose of 10 mg cisapride, 2) a single oral dose of placebo, 3) a perfusion of graded doses of Ang II (from 1-4 ng/kg.min), 4) a perfusion of placebo, and 5) a single oral dose of 10 mg cisapride associated with a perfusion of Ang II. The oral doses of cisapride and placebo were also administered after a 3-day period of a low sodium diet (10 mmol/day). Plasma aldosterone levels increased significantly within 90 min after the administration of cisapride without any change in renin levels. The comparison between the net increase in aldosterone production induced by cisapride, Ang II, and cisapride plus Ang II showed that the stimulatory effects of cisapride and Ang II on aldosterone secretion were only additive. Similarly, the increase in plasma aldosterone levels induced by a sodium-restricted diet was just additive with the cisapride-evoked stimulation of aldosterone secretion. These results provide further evidence that the action of 5-HT on glomerulosa cells is mediated through activation of 5-HT4 receptors. The data also indicate that in humans, 5-HT does not potentiate the stimulatory effect of Ang II on aldosterone secretion.

Characterization of the somatostatin receptor subtype in a bronchial carcinoid tumor responsible for Cushing's syndrome.

Small ACTH-secreting carcinoid tumors responsible for Cushing's syndrome are often difficult to localize using available radiological investigations. Somatostatin receptors have been found in about 90% of carcinoid tumors studied, leading to a new approach for the localization of tumors or metastasis by using radiolabeled somatostatin analogs. We report a case of Cushing's syndrome due to an ACTH-secreting bronchial carcinoid tumor, completely suppressible with octreotide treatment and evidenced by body scintigraphy with 111In-labeled pentreotide. After removal, which led to patient recovery, the tumor was studied in vitro. In situ hybridization, using a complementary DNA probe, revealed POMC messenger ribonucleic acid in a subpopulation of tumor cells. These cells were labeled by immunochemistry using an antiserum directed against ACTH. Confocal laser scanning microscopy analysis showed that the ACTH-immunoreactive peptide was sequestered in secretory granules. Autoradiographic labeling using [125I-Tyrzero,D-Trp8]somatostatin-14 demonstrated the presence of somatostatin-binding sites in the whole tumor tissue. The relative affinities of various selective somatostatin analogs and the ability of GTP to inhibit radioligand binding suggested that the receptor expressed in the tumor cells belonged to the SSTR-2 subtype.

Pharmacokinetics and efficacy of a long-acting formulation of the new somatostatin analog BIM 23014 in patients with acromegaly.

The treatment of acromegalics with somatostatin analogs requires continuous sc infusion using pumps or several sc injections daily. Long-acting formulations (BIM-LA) of BIM 23014 (BIM) using delayed microcapsules may provide a more convenient form of therapy. Fourteen acromegalics whose GH secretion had not been normalized by transphenoidal surgery followed, in 10 cases, by pituitary radiotherapy (performed at least 2 yr before the study) were studied. Eight of these patients participated in an initial study of the pharmacokinetics of BIM-LA, after which a 6-month efficacy study was undertaken. The 8 patients in the pharmacokinetic study had an initial blood sample collected for measurements of plasma GH and insulin-like growth factor-I (IGF-I) levels before the im injection of 30 mg BIM-LA, and blood samples were subsequently taken 2, 4, 6, and 8 h after injection and then twice a week for a month. Plasma IGF-I levels were measured on days 4, 14, 20, and 30 after the injection. Assays of plasma GH, IGF-I, and BIM levels were performed by RIAs. The results showed that plasma GH levels were markedly reduced from 26.0 +/- 2.0 to 2.5 +/- 0.2 micrograms/L 2 h after BIM-LA injection and remained lower than 5 micrograms/mL for the 11 following days. Plasma GH levels increased to 5.5 +/- 1.2 micrograms/L on day 14 and returned to basal values 23 days after injection. Similarly, plasma IGF-I decreased from an initial level of 656 +/- 43 to 324 +/- 23 ng/mL on day 4 and remained close to the normal range for the following 10 days. Plasma BIM levels reached a peak 2 h after the injection (7.2 +/- 2.3 ng/mL) and remained higher than or close to 1 ng/mL until the 14th day after injection. This initial study showed that a single injection of 30 mg BIM-LA effectively suppressed GH and IGF-I secretion for at least 14 days, in accordance with the kinetics of the drug in plasma. Based on the results of this initial study, 30 mg BIM-LA were injected twice monthly for 6 months in all 14 patients. All of the subjects had a basal evaluation before treatment with BIM-LA and were then subjected to assessment of clinical, pituitary, and hormonal parameters. Patients were evaluated after 3 and 6 months of treatment on the same basis as that previously used when starting the BIM-LA therapy. Plasma BIM levels were measured monthly. Clinical signs of acromegaly improved during the treatment.(ABSTRACT TRUNCATED AT 400 WORDS)

Vasopressin stimulates cortisol secretion from human adrenocortical tissue through activation of V1 receptors.

It has previously been shown that arginine vasopressin (AVP) exerts a direct stimulatory action on rat adrenocortical cells. In the present study, we have investigated the possible effect of AVP on cortisol secretion by normal human adrenocortical tissue. The occurrence of endogenous AVP in the human adrenal gland has been studied by means of the indirect immunofluorescence technique. The presence of AVP-containing cells was observed in both cortex and medulla. The action of AVP on corticosteroidogenesis has been investigated in vitro using a perifusion system technique coupled to a specific RIA for cortisol. Graded doses of AVP (from 10(-11)-10(-9) M) increased cortisol secretion in a dose-dependent manner (ED50, 4.5 x 10(-11) M). AVP also induced a significant stimulation of cortisol release from acutely dispersed adrenocortical cells. Prolonged administration of AVP (3 h) induced a rapid and transient increase in cortisol output, followed by a gradual decline in cortisol secretion. Repeated pulses of AVP, given at 90-min intervals, resulted in reproducible stimulations of cortisol output. Selective agonists and antagonists have been used to determine the type of receptor involved in the response of adrenocortical cells to AVP. Oxytocin at doses up to 10(-7) M had virtually no effect on cortisol secretion. The stimulatory effect of AVP was blocked by the V1 antagonist [beta-mercapto-beta,beta-cyclopentamethylene propionyl 1, OMe-Tyr2, Arg8]AVP. In contrast, the V2 antagonist [d(CH2)5D-Phe2,Ile4,Ala9-NH2]AVP did not affect the response of the adrenal gland to AVP. The selective V2 agonist [deamino-Cys1,D-Arg8]AVP did not mimic the stimulatory effect of AVP on cortisol secretion. Taken together, these results suggest that AVP, locally released by intracortical cells, may act as a paracrine factor to stimulate adrenal steroidogenesis in man. The effect of AVP on cortisol secretion appears to be mediated through activation of typical V1 receptors.

Effects of 10 days administration of percutaneous dihydrotestosterone on the pituitary-testicular axis in normal men.

Dihydrotestosterone (DHT) was administered percutaneously in a dose of 125 mg twice daily for 10 days to 12 normal men. Basal plasma levels of testosterone (T), 17 beta-estradiol (E2), and LH were measured every 2 days in these men and every 5 days in subjects from a control group receiving placebo. The daytime course of plasma hormone levels between two DHT applications was studied in six men. LRH tests were performed in nine men before and on day 10 of DHT administration. Plasma levels of free T and free E2, and T - E-binding globulin capacity and affinity were measured in six men before and on days 5 and 10 of DHT administration. Before DHT administration, there was no difference in basal plasma levels of T, DHT, E2, and LH between the control and the DHT-treated group. In the latter group, plasma DHT levels increased sharply from 0.52 +/- (+/- SE) to 3.70 +/- 0.92 ng/ml on day 2 (P less than 0.001) during DHT treatment. Plasma T, E2, and LH levels decreased significantly from 7.33 +/- 0.74 to 1.33 +/- 0.54 ng/ml (P less than 0.001), from 46 +/- 5 to 20 +/- 3 pg/ml (P less than 0.01), and from 7.8 +/- 1 to 4.2 mIU/ml (P less than 0.05), respectively. Except for a small decrease in plasma DHT (P less than 0.05) 12 h after the previous DHT application, hormone levels were stable during the time between the two DHT treatments. The responses of LH and FSH to LRH were not different before and on day 10 of DHT administration. Plasma levels of free T and free E2 as well as those of total T and E2 decreased; however, the percentages of unbound T and E2 were not different before and during DHT administration. T - E-binding globulin capacity and affinity were not modified by DHT administration. Changes in plasma DHT levels were negatively correlated with those in The results of this study demonstrate that 10-days DHT administration has an inhibitory effect on the hypothalamo-pituitary-testicular axis in normal men.