Von Hippel-Lindau disease: a single gene, several hereditary tumors.

The Von Hippel-Lindau (VHL) disease is an autosomal dominant disorder characterized by the predisposition for multiple tumors caused by germline mutations in the tumor suppressor gene VHL. This disease is associated with a high morbidity and mortality and presents a variable expression, with different phenotypes from family to family, affecting different organs during the lifetime. The main manifestations of VHL are hemangioblastomas of the central nervous system and retina, renal carcinomas and cysts, bilateral pheochromocytomas, cystic and solid tumors of the pancreas, cystadenomas of the epididymis, and endolymphatic sac tumors. The discovery of any of the syndrome components should raise suspicion of this disease and other stigmas must then be investigated. Due to the complexities associated with management of the various VHL manifestation, the diagnosis and the follow-up of this syndrome is a challenge in the clinical practice and a multidisciplinary approach is needed. The particular relevance to endocrinologists is the detection of pheochromocytomas in 35% and islet cell tumors in 17% of VHL patients, which can be associated with hypertension, hypoglycemia, cardiac arrhythmias, and carcinoid syndrome. The purpose of this review is to define the Von Hippel-Lindau syndrome addressing its clinical aspects and classification, the importance of genetic counseling and to propose a protocol for clinical follow-up.

Aberrant hormone receptors in primary aldosteronism.

The mechanisms involved in the renin-independent regulation of aldosterone secretion in primary aldosteronism are poorly understood. In ACTH-independent Cushing's syndrome, cortisol secretion can be regulated by the aberrant expression of G-protein coupled receptors (GPCRs) in unilateral tumors and bilateral macronodular adrenal hyperplasia. By analogy, some recent studies identified overexpression or function of several GPCR as a potential cause for excess aldosterone production in some aldosteronomas and in bilateral idiopathic hyperaldosteronism. Initial studies have used in vitro techniques, while the clinical aldosterone responses were not assessed. More recently, several receptors have been shown to be expressed in aldosterone-producing adrenal tumors in vitro and to regulate aberrantly renin-independent aldosterone secretion in vivo. The prevalence of aberrant hormone receptors in primary aldosteronism could be elevated, but larger systematic studies are required to establish its true frequency. The identification of aberrant adrenal GPCRs by in vivo functional studies offers the potential for novel pharmacological therapies that either suppress the endogenous ligands or block the receptor with specific antagonists.

Effect of two active compounds obtained from the essential oil of Cordia verbenacea on the acute inflammatory responses elicited by LPS in the rat paw.

BACKGROUND AND PURPOSE: alpha-Humulene and trans-caryophyllene are sesquiterpene compounds identified in the essential oil of Cordia verbenacea which display topical and systemic anti-inflammatory effects in different experimental models. However, the molecular mechanisms through which they exert their anti-inflammatory activity still remain unclear. Here, we evaluate the effects of alpha-humulene and trans-caryophyllene on the acute inflammatory responses elicited by LPS. EXPERIMENTAL APPROACH: The biological activities of alpha-humulene and trans-caryophyllene were investigated in a model of acute inflammation in rat paw, induced by LPS and characterized by paw oedema, neutrophil recruitment, cytokine production, activation of MAP kinases and NF-kappaB and up-regulated expression of kinin B(1) receptors. KEY RESULTS: Treatment with either alpha-humulene or trans-caryophyllene effectively reduced neutrophil migration and activation of NF-kappaB induced by LPS in the rat paw. However, only alpha-humulene significantly reduced the increase in TNF-alpha and IL-1beta levels, paw oedema and the up-regulation of B(1) receptors following treatment with LPS. Both compounds failed to interfere with the activation of the MAP kinases, ERK, p38 and JNK. CONCLUSIONS AND IMPLICATIONS: Both alpha-humulene and trans-caryophyllene inhibit the LPS-induced NF-kappaB activation and neutrophil migration, although only alpha-humulene had the ability to prevent the production of pro-inflammatory cytokines TNF-alpha and IL-1beta and the in vivo up-regulation of kinin B(1) receptors. These data provide additional molecular and functional insights into the beneficial effects of the sesquiterpenes alpha-humulene and trans-caryophyllene isolated from the essential oil of Cordia verbenacea as agents for the management of inflammatory diseases.

Aberrant GPCR expression is a sufficient genetic event to trigger adrenocortical tumorigenesis.

Aberrant expression of G protein-coupled receptors (GPCR) in the adrenal cortex is observed in some cases of ACTH-independent macronodular adrenal hyperplasias and adenomas associated with Cushing syndrome (CS). Although there is clinical evidence for the implication of these receptors in abnormal regulation of cortisol secretion, whether this aberrant expression also directly causes the development of a benign adrenocortical tumor is an open question. Cell transplantation provides a way to study genes that may be important in human tumor development. The system we developed uses genetically modified adrenocortical cells transplanted into adrenalectomized immunodeficient mice, which form a functional tissue structure. We observed that enforcing expression of the gastric inhibitory polypeptide (GIP) receptor or the luteinizing hormone (LH) receptor genes (taken as canonical examples of aberrantly expressed GPCRs) in adrenocortical cells resulted in the formation of hyperplastic tissues and the development of Cushing syndrome features in transplanted mice.

Characterization of the mechanism involved in the relaxant response of dopexamine in the guinea pig pulmonary artery in vitro.

Dopexamine is a synthetic catecholamine used for the management of low-cardiac-output states. The purpose of this study was to characterize some of the mechanisms underlying dopexamine-mediated relaxation in the guinea pig pulmonary artery (PA) in vitro. Dopexamine (EC50, 1.2 microM; Rmax, 100%), like dobutamine (EC50, 1.4 microM, Rmax, 93.3%), prostacyclin (PGI2; EC50, 37 nM; Rmax, 96.2%), sodium nitroprusside (EC50, 370 pM; Rmax, 96.9%), forskolin (EC50, 47 pM: Rmax, 98.6%), and SKF 38393 (EC50, 120 nM; Rmax, 100%), caused graded relaxation in rings of PA precontracted by phenylephrine. The dopexamine vasorelaxation was antagonized by propranolol (1 microM), SCH 23390 (100 nM, a D1-dopamine antagonist), sulpiride (1 microM), glibenclamide (30 microM), tetraethylammonium (3 mM), apamin (100 nM), charybdotoxin (100 nM), SQ 22536 (10 microM, an adenylyl cyclase inhibitor), KT 5720 (10 microM, a protein kinase A inhibitor) and by calcitonin gene-related peptide (CGRP) or vasoactive intestinal peptide (VIP)-receptor antagonists (both 100 nM), as well as by chymotrypsin (1 U/ml). Neither the prior incubation of N(G)-nitro-L-arginine (100 pM), indomethacin (1 microM), nor removal of the vascular endothelium interfered with dopexamine vasorelaxation response in PA. Thus dopexamine relaxation in PA is mediated by activation of beta-adrenoceptors and dopamine receptors, and by the opening of both low- and high-conductance Ca2+-activated K+ channels, partially through adenosine triphosphate (ATP)-sensitive K+ channels. In addition, dopexamine-induced relaxation in PA seems to involve the release of peptides such as VIP and CGRP, an effect mediated by a cyclic adenosine monophosphate (cAMP)-dependent mechanism.