Sclerosing Paragangliomas: Correlations of Histological Features with Patients' Genotype and Vesicular Monoamine Transporter Expression.

Paragangliomas and pheochromocytomas are rare neuroendocrine tumors, carrying a germ-line mutation in 40% patients. Sclerosis is a rare histological feature in these tumors. We investigated the possible correlations between histological findings, first sclerosis, immunoreactivity for vesicular catecholamine transporters (VMAT1/VMAT2) and patients' genotype in a consecutive series of 57 tumors (30 paragangliomas and 27 pheochromocytomas) from 55 patients. The M-GAPP grading system, sclerosis (0-3 scale) and VMAT1/VMAT2 (0-6 scale) immunoreactivity scores were assessed. Germ-line mutations of Succinate Dehydrogenase genes, RET proto-oncogene and Von Hippel Lindau tumor suppressor gene were searched. A germ-line mutation was found in 25/55 (45.5%) patients, mainly with paraganglioma (N = 14/30, 46,66%). Significant (score ≥ 2) tumor sclerosis was found in 9 (16.1%) tumors, i.e., 7 paragangliomas and 2 pheochromocytomas, most of them (8/9) from patients with a germ-line mutation. M-GAPP score was higher in the mutation status (in 76% of patients involving the SDHx genes, in 12% the RET gene and in the remaining 12% the VHL gene) and in tumors with sclerosis (p < 0.05). Spearman's rank correlation showed a strong correlation of germ-line mutations with M-GAPP (p < 0.0001) and sclerosis (p = 0.0027) scores; a significant correlation was also found between sclerosis and M-GAPP scores (p = 0.029). VMAT1 expression was higher in paragangliomas than in pheochromocytomas (p = 0.0006), the highest scores being more frequent in mutation-bearing patients' tumors (p < 0.01). VMAT2 was highly expressed in all but two negative tumors. Sclerosis and VMAT1 expression were higher in paragangliomas than in pheochromocytomas; tumor sclerosis, M-GAPP and VMAT1 scores were associated to germ-line mutations. Sclerosis might represent a histological marker of tumor susceptibility, prompting to genetic investigations in paragangliomas.

Vesicular monoamine transporters expression in pheochromocytomas and paragangliomas according to scintigraphy and positron emission tomography behavior.

BACKGROUND: The expression of vesicular catecholamine transporters (VMAT1 and 2) in pheochromocytomas (PHEOs) and paragangliomas (PGLs) and the possible relationships with [18F]FDOPA PET/CT and [123I]MIBG scintigraphy uptake are unknown. Our purpose was to investigate possible correlations of either VMAT1 and VMAT2 expression with the functional imaging in patients with PHEOs and PGLs. METHODS: An observational 3-year time study was performed by enrolling 31 consecutive patients with PHEO (N.=17) or PGL (N.=14). They underwent the same diagnostic work-up; moreover, [123I]MIBG SPECT/CT (N.=20) and [18F]FDOPA PET/CT (N.=14) were performed in a subset of patients. After surgery, routine histology and semiquantitative analysis of VMAT1/VMAT2 immunoreactivity were carried out in all cases. RESULTS: VMAT1 immunoreactivity was found in all tumors, but two PHEOs. VMAT1 immunoreactivity was higher in PGLs than in PHEOs, though at not significant extent. Elevated VMAT2 immunoreactivity score was present in all but two negative tumors. Normal [123I]-MIBG uptake was independent from VMAT1/2 immunoreactivity. Patients undergoing [18F]FDOPA PET/CT showed a high score level of both VMATs and were detected by the technique in all cases. CONCLUSIONS: VMAT1 and VMAT2 are highly expressed in most tumors, though VMAT1 immunoreactivity is apparently prevalent in PGLs as compared to PHEOs. Presence and expression of VMAT1 and VMAT2 are not limiting factors for MIBG uptake. The status of VMAT expression might help to understand why the more frequently used radiotracers do not always have the expected diagnostic performance. Finally, the present study points out the importance of developing new radiotracers with higher sensitivity, specificity and accuracy consequently reducing healthcare costs.

A case report of a TDM-guided optimization of mitotane for a safe and effective long-term treatment.

A 43-years old woman was diagnosed an adrenocortical carcinoma (AC) that was excised, whereas two lung metastases were un-operable. Mitotane 6 g/day was started as standard therapy but it was responsible for severe central nervous system (CNS) and gastrointestinal toxicities associated with a 10 kg body weight loss. A therapeutic drug monitoring (TDM) protocol demonstrated that mitotane plasma concentrations (>30 mg/L) exceeded the therapeutic range (14-20 mg/L) and increased even when drug daily dose was reduced by 50%. The increase in drug plasma concentrations was probably due to body slimming. Under continuous TDM control, a reduced mitotane dose (1.5 g/day) was definitively administered and it proved to be tolerable and effective. Indeed, lung metastases were excised and two years later there was no evidence of other neoplastic lesions. In conclusion, the adoption of therapeutic mitotane monitoring allowed the treatment of an AC patient with a reduced, tolerable and effective dose.

Adrenalectomy Lowers Incident Atrial Fibrillation in Primary Aldosteronism Patients at Long Term.

Primary aldosteronism (PA) causes cardiovascular damage in excess to the blood pressure elevation, but there are no prospective studies proving a worse long-term prognosis in adrenalectomized and medically treated patients. We have, therefore, assessed the outcome of PA patients according to treatment mode in the PAPY study (Primary Aldosteronism Prevalence in Hypertension) patients, 88.8% of whom were optimally treated patients with primary (essential) hypertension (PH), and the rest had PA and were assigned to medical therapy (6.4%) or adrenalectomy (4.8%). Total mortality was the primary end point; secondary end points were cardiovascular death, major adverse cardiovascular events, including atrial fibrillation, and total cardiovascular events. Kaplan-Meier and Cox analysis were used to compare survival between PA and its subtypes and PH patients. After a median of 11.8 years, complete follow-up data were obtained in 89% of the 1125 patients in the original cohort. Only a trend (P=0.07) toward a worse death-free survival in PA than in PH patients was observed. However, at both univariate (90.0% versus 97.8%; P=0.002) and multivariate analyses (hazard ratio, 1.82; 95% confidence interval, 1.08-3.08; P=0.025), medically treated PA patients showed a lower atrial fibrillation-free survival than PH patients. By showing that during a long-term follow-up adrenalectomized aldosterone-producing adenoma patients have a similar long-term outcome of optimally treated PH patients, whereas, at variance, medically treated PA patients remain at a higher risk of atrial fibrillation, this large prospective study emphasizes the importance of an early identification of PA patients who need adrenalectomy as a key measure to prevent incident atrial fibrillation.

Maffucci Syndrome Associated With Adrenocorticotropic Hormone-Independent Bilateral Macronodular Adrenal Hyperplasia.

CONTEXT: Maffucci syndrome is a rare, nonhereditary, mesodermal dysplastic disease characterized by the presence of multiple hemangiomas and enchondromas. This pathological condition, which is often unrecognized, is associated with a high prevalence of benign and malignant endocrine tumors involving pituitary, adrenal, thyroid, and parathyroid glands. CASE DESCRIPTION: We describe the case of a young patient presenting a history suggestive of secondary arterial hypertension and typical features of Maffucci syndrome (multiple hemangiomas and enchondromas), which were unrecognized over the previous 3 decades. Given that endocrine diseases are common causes of secondary arterial hypertension and are often associated with Maffucci syndrome, a comprehensive diagnostic workup was performed, revealing the presence of large bilateral adrenal masses (70 mm right, 35 mm left) and autonomous cortisol secretion (adrenocorticotropic hormone-independent Cushing syndrome). The patient underwent a bilateral adrenalectomy, and steroid replacement therapy was initiated. Surgery resulted in a normalization of arterial blood pressure, and antihypertensive treatment was discontinued. Histological examinations revealed morphological features of primary bilateral macronodular adrenal hyperplasia. CONCLUSIONS: Early recognition and lifelong monitoring of Maffucci syndrome is required to identify and treat possible associated endocrine diseases and malignancies. Among them, unilateral cortical adrenal masses have been previously described, but to our knowledge, this is the first reported case of Maffucci syndrome associated with primary bilateral macronodular adrenal hyperplasia. Additional studies are needed to establish the etiopathological link between these 2 entities and, more in general, between Maffucci syndrome and endocrine diseases, but possible common genetic alterations may be suggested.

Endocrine and haemodynamic stress responses to an arithmetic cognitive challenge.

OBJECTIVE: We aimed at developing and validating a simple, highly repeatable computer-based tool, which could be employed to simulate the effects of an acute mental stress on endocrine and haemodynamic stress responses. METHODS: Fifteen subjects underwent a mental cognitive challenge, employing an ad hoc designed web tool (available at http://bagame.altervista.org) that proposed a series of random arithmetic operations (addictions or subtractions) between one- to three-digit numbers for 10 minutes. We measured plasma epinephrine, norepinephrine, cortisol, and ACTH, in addition to heart rate (HR), systolic (SBP) and diastolic (DBP) blood pressure throughout the test. RESULTS: The arithmetic mental challenge promptly activated the sympatho-adrenomedullary axis (epinephrine +112±24%, p<0.05; norepinephrine +37±13%, p<0.004) and the hypothalamic-pituitary-adrenocortical axis (cortisol +25±7%, p<0.008; ACTH +97±44%, p<0.008), which in turn exerted stimulatory effects on the cardiovascular system (HR +18±4%, p<0.05; SBP +112±24%, p<0.05; DBP +34±8%, p<0.05) in all subjects, without any symptoms and regardless of the individuals' mental arithmetic ability. CONCLUSIONS: We developed and validated a computer-based tool that is effective for simulating endocrine and haemodynamic responses to an acute mental stress. This novel tool is easy-to-use, freely-accessible, and it can be employed to further investigate stress-related pathophysiological mechanisms and their role in cardiovascular diseases.

Cholecalciferol treatment downregulates renin-angiotensin system and improves endothelial function in essential hypertensive patients with hypovitaminosid D.

BACKGROUND: Vitamin D deficiency is related to an increased prevalence of cardiovascular disease. Renin-angiotensin-aldosterone system suppression and vascular dysfunction are considered among the main mechanisms implicated in this association. However, interventional studies demonstrating that vitamin D replacement reduces circulating renin-angiotensin-aldosterone components and improves vascular function in humans are still lacking. METHODS: Thirty-three consecutive patients with essential hypertension and hypovitaminosis D underwent therapy with cholecalciferol 50 000 IU/week orally for 8 weeks. Thirty-three hypertensive patients with normal vitamin D levels and 20 normotensive individuals were also enrolled as control groups. At baseline and at the end of the study, we evaluated plasma renin activity, circulating renin, angiotensin II, aldosterone and plasma vitamin D levels. Endothelial function [flow-mediated dilation (FMD)], carotid-femoral pulse wave velocity and augmentation index, peripheral and central blood pressure were also acquired. RESULTS: After 8-week cholecalciferol administration, all treated patients normalized plasma 25(OH)D values. Furthermore, a reduction in plasma levels of plasma renin activity (1.17 ±â€Š0.3 vs 1.51 ±â€Š0.4 ng/ml per h, P = 0.02), renin (13.4 ±â€Š1.7 vs 19.2 ±â€Š2.9 pg/ml, P < 0.001), angiotensin II (11.6 ±â€Š1.6 vs 15.8 ±â€Š2.7 pg/ml, P = 0.02) was observed at the end of the study. FMD was significantly increased after cholecalciferol treatment (4.4 ±â€Š2.6 vs 3.3 ±â€Š2.1%, P < 0.05), in the absence of changes of brachial artery diameter and endothelium-independent vasodilation. Carotid-femoral pulse wave velocity and augmentation index were not modified, as well peripheral and central blood pressure. CONCLUSION: The restoration of normal vitamin D levels after 8-week cholecalciferol treatment is able to inhibit peripheral renin-angiotensin system and improve FMD in essential hypertensive patients with hypovitaminosis D.

Cushing's Syndrome and Steroid Dementia.

Cushing's Syndrome (CS) is associated with a specific spectrum of dementia-like symptoms, including psychiatric disorders, such as major depression, anxiety and mania, and neurocognitive alterations, like impairment of memory and concentration. This pattern of clinical complications, which significantly impair the health-related quality of life of CS patients, is sometimes referred to as "steroid dementia syndrome" (SDS). The SDS is the result of anatomical and functional anomalies in brain areas involved in the processing of emotion and cognition, which are only partially restored after the biochemical remission of the disease. Therefore, periodical neuropsychiatric evaluations are recommended in all CS patients, and a long-term follow-up is required after normalization of hypercortisolism. Recent evidences demonstrate that three classes of drugs (glucocorticoid receptor antagonists, steroidogenesis inhibitors, and pituitary tumor-targeted drugs), which are used for medical treatment of CS, can rapidly relief neuropsychiatric symptoms of SDS. Furthermore, several psychoactive medications have demonstrated effectiveness in the treatment of symptoms induced by the acute or chronic glucocosteroid administration. In this paper, a review of the current and future patents for the treatment and prevention of CS and SDS will be presented.

Genome-wide association study identifies CAMKID variants involved in blood pressure response to losartan: the SOPHIA study.

BACKGROUND: Essential hypertension arises from the combined effect of genetic and environmental factors. A pharmacogenomics approach could help to identify additional molecular mechanisms involved in its pathogenesis. AIM: The aim of SOPHIA study was to identify genetic polymorphisms regulating blood pressure response to the angiotensin II receptor blocker, losartan, with a whole-genome approach. MATERIALS & METHODS: We performed a genome-wide association study on blood pressure response in 372 hypertensives treated with losartan and we looked for replication in two independent samples. RESULTS: We identified a peak of association in CAMK1D gene (rs10752271, effect size -5.5 ± 0.94 mmHg, p = 1.2 × 10(-8)). CAMK1D encodes a protein that belongs to the regulatory pathway involved in aldosterone synthesis. We tested the specificity of rs10752271 for losartan in hypertensives treated with hydrochlorothiazide and we validated it in silico in the GENRES cohort. CONCLUSION: Using a genome-wide approach, we identified the CAMK1D gene as a novel locus associated with blood pressure response to losartan. CAMK1D gene characterization may represent a useful tool to personalize the treatment of essential hypertension.

Aldosterone suppression on contralateral adrenal during adrenal vein sampling does not predict blood pressure response after adrenalectomy.

CONTEXT: Adrenal vein sampling (AVS) is the only reliable means to distinguish between aldosterone-producing adenoma and bilateral adrenal hyperplasia, the two most common subtypes of primary aldosteronism (PA). AVS protocols are not standardized and vary widely between centers. OBJECTIVE: The objective of the study was to retrospectively investigate whether the presence of contralateral adrenal (CL) suppression of aldosterone secretion was associated with improved postoperative outcomes in patients who underwent unilateral adrenalectomy for PA. SETTING: The study was carried out in eight different referral centers in Italy, Germany, and Japan. PATIENTS: From 585 consecutive AVS in patients with confirmed PA, 234 procedures met the inclusion criteria and were used for the subsequent analyses. RESULTS: Overall, 82% of patients displayed contralateral suppression. This percentage was significantly higher in ACTH stimulated compared with basal procedures (90% vs 77%). The CL ratio was inversely correlated with the aldosterone level at diagnosis and, among AVS parameters, with the lateralization index (P = .02 and P = .01, respectively). The absence of contralateral suppression was not associated with a lower rate of response to adrenalectomy in terms of both clinical and biochemical parameters, and patients with CL suppression underwent a significantly larger reduction in the aldosterone levels after adrenalectomy. CONCLUSIONS: For patients with lateralizing indices of greater than 4 (which comprised the great majority of subjects in this study), CL suppression should not be required to refer patients to adrenalectomy because it is not associated with a larger blood pressure reduction after surgery and might exclude patients from curative surgery.

Genetic spectrum and clinical correlates of somatic mutations in aldosterone-producing adenoma.

Primary aldosteronism is the most common form of secondary hypertension. Somatic mutations in KCNJ5, ATP1A1, ATP2B3, and CACNA1D have been described in aldosterone-producing adenomas (APAs). Our aim was to investigate the prevalence of somatic mutations in these genes in unselected patients with APA (n=474), collected through the European Network for the Study of Adrenal Tumors. Correlations with clinical and biochemical parameters were first analyzed in a subset of 199 patients from a single center and then replicated in 2 additional centers. Somatic heterozygous KCNJ5 mutations were present in 38% (180/474) of APAs, whereas ATP1A1 mutations were found in 5.3% (25/474) and ATP2B3 mutations in 1.7% (8/474) of APAs. Previously reported somatic CACNA1D mutations as well as 10 novel CACNA1D mutations were identified in 44 of 474 (9.3%) APAs. There was no difference in the cellular composition of APAs or in CYP11B2, CYP11B1, KCNJ5, CACNA1D, or ATP1A1 gene expression in APAs across genotypes. Patients with KCNJ5 mutations were more frequently female, diagnosed younger, and with higher minimal plasma potassium concentrations compared with CACNA1D mutation carriers or noncarriers. CACNA1D mutations were associated with smaller adenomas. These associations were largely dependent on the population structure of the different centers. In conclusion, recurrent somatic mutations were identified in 54% of APAs. Young women with APAs are more likely to be KCNJ5 mutation carriers; identification of specific characteristics or surrogate biomarkers of mutation status may lead to targeted treatment options.

Excess dietary sodium and inadequate potassium intake by hypertensive patients in Italy: results of the MINISAL-SIIA study program.

INTRODUCTION: The aim of the study was to assess the age-specific, sex-specific, and region-specific average sodium and potassium intake and its association with anthropometric characteristics in a sample of the Italian adult hypertensive population. METHODS: A total of 1232 hypertensive patients were recruited consecutively by 47 centers recognized by the Italian Society of Hypertension. The enrolled participants were on stable antihypertensive treatment. Anthropometric indices, blood pressure, 24-h urinary sodium, and potassium excretion were measured and used as proxy for the average daily sodium and potassium intake. RESULTS: The average sodium intake was 172  mmol (or 10.1  g of salt/day) among men and 138 (or 8.1) among women, with no difference among geographical areas. Over 90% of men and 81% of women had a consumption higher than the recommended standard dietary intake of 5  g/day. The average potassium intake was 63 and 56  mmol, respectively in men and women, again without geographical differences, nearly 92% of men and 95% of women having an intake lower than the recommended intake (100  mmol/day or 3.9  g/day). There was a significant trend to a gradual decrease in sodium intake with age in both sexes (P <0.001). There was also a direct association between BMI and sodium intake in both sexes, this association being independent of age (P < 0.001). CONCLUSION: In this national sample of the Italian hypertensive population, dietary sodium intake was largely higher and potassium intake much lower than the recommended intakes, and this was true for all geographical areas. Overweight and obese hypertensive patients had particularly high sodium intakes.

Somatic ATP1A1, ATP2B3, and KCNJ5 mutations in aldosterone-producing adenomas.

Aldosterone-producing adenomas (APAs) cause a sporadic form of primary aldosteronism and somatic mutations in the KCNJ5 gene, which encodes the G-protein-activated inward rectifier K(+) channel 4, GIRK4, account for ≈40% of APAs. Additional somatic APA mutations were identified recently in 2 other genes, ATP1A1 and ATP2B3, encoding Na(+)/K(+)-ATPase 1 and Ca(2+)-ATPase 3, respectively, at a combined prevalence of 6.8%. We have screened 112 APAs for mutations in known hotspots for genetic alterations associated with primary aldosteronism. Somatic mutations in ATP1A1, ATP2B3, and KCNJ5 were present in 6.3%, 0.9%, and 39.3% of APAs, respectively, and included 2 novel mutations (Na(+)/K(+)-ATPase p.Gly99Arg and GIRK4 p.Trp126Arg). CYP11B2 gene expression was higher in APAs harboring ATP1A1 and ATP2B3 mutations compared with those without these or KCNJ5 mutations. Overexpression of Na(+)/K(+)-ATPase p.Gly99Arg and GIRK4 p.Trp126Arg in HAC15 adrenal cells resulted in upregulation of CYP11B2 gene expression and its transcriptional regulator NR4A2. Structural modeling of the Na(+)/K(+)-ATPase showed that the Gly99Arg substitution most likely interferes with the gateway to the ion binding pocket. In vitro functional assays demonstrated that Gly99Arg displays severely impaired ATPase activity, a reduced apparent affinity for Na(+) activation of phosphorylation and K(+) inhibition of phosphorylation that indicate decreased Na(+) and K(+) binding, respectively. Moreover, whole cell patch-clamp studies established that overexpression of Na(+)/K(+)-ATPase Gly99Arg causes membrane voltage depolarization. In conclusion, somatic mutations are common in APAs that result in an increase in CYP11B2 gene expression and may account for the dysregulated aldosterone production in a subset of patients with sporadic primary aldosteronism.

Role of 18F-DOPA PET/CT in diagnosis and follow-up of adrenal and extra-adrenal paragangliomas.

PURPOSE: The objective of this study was to establish the clinical value of F-DOPA PET/CT in patients with adrenal and extra-adrenal paragangliomas (PGLs). METHODS: Twenty-six consecutive patients with suspected or recurrent PGL underwent MR (and/or CT) and F-DOPA PET/CT. Histopathology confirmation was obtained in 20 cases. Genetic analysis on known susceptibility genes for PGL (VHL, RET, SDHx, TMEM127) was available in 13 patients. RESULTS: Fourteen patients were affected by PGL (8 with head/neck location, 6 with abdominal/thoracic location), whereas 12 showed masses of other origin. Three patients proved to be SDHD, 1 SDHB, 2 SDHC, and 1 TMEM127 mutation carriers. F-DOPA PET/CT showed pathological uptake in 13 of 26 patients. The procedure identified all PGLs except one with bone metastases (previous malignant adrenal PGL). No uptake was found in patients without proven PGL. Thus, in the whole group, F-DOPA PET/CT sensitivity was 92.8%, and specificity was 100% with positive and negative predictive values of 100% and 92.3%, respectively. Total diagnostic accuracy was 96.2%. In the head/neck subgroup, sensitivity, specificity, positive and negative predictive values, and diagnostic accuracy were 100%. In the abdominal location, sensitivity was 80% and specificity was 100%, and positive and negative predictive values were 100% and 91.7%, respectively. Abdominal diagnostic accuracy was 93.7%. Radiotracer uptake was superimposable in head/neck PGLs versus abdominal PGLs and in mutated versus wild-type patients. CONCLUSIONS: The high diagnostic performance of F-DOPA PET/CT showed this technique to be a useful tool in detecting PGLs, above all those located at the head/neck site, regardless of the genetic pattern.

Cholecalciferol administration blunts the systemic renin-angiotensin system in essential hypertensives with hypovitaminosis D.

INTRODUCTION: Vitamin D plasma levels are negatively associated with blood pressure and cardiovascular mortality, and vitamin D supplementation reduces cardiovascular events. Renin-angiotensin system (RAS) suppression may be one of the mechanisms involved. However, there are no interventional prospective studies demonstrating a reduction in circulating RAS components after vitamin D treatment. METHODS: Fifteen consecutive drug-free patients with essential hypertension and hypovitaminosis D underwent therapy with an oral dose of 25000 I.U. of cholecalciferol once a week for two months, while maintaining a constant-salt diet. In basal conditions and at the end of the study, RAS activity (plasma angiotensinogen, renin, PRA, angiotensin II, aldosterone and urinary angiotensinogen) was investigated, in addition to blood pressure and plasma vitamin D levels (25(OH)D). RESULTS: After cholecalciferol administration, all patients exhibited normalized plasma 25(OH)D values. At the end of the study, a reduction (p < 0.05) in plasma renin and aldosterone, and a decrement, although not significant, of PRA and angiotensin II, was observed. No difference was found in plasma and urinary angiotensinogen or blood pressure values. CONCLUSIONS: Our data indicate that in essential hypertensives with hypovitaminosis D, pharmacological correction of vitamin D levels can blunt systemic RAS activity.

Endothelial dysfunction in small arteries of essential hypertensive patients: role of cyclooxygenase-2 in oxidative stress generation.

Essential hypertensive patients show a reduced nitric oxide availability secondary to oxidative stress generation in peripheral microcirculation. Cyclooxygenase (COX) contributes to reduce nitric oxide availability. We assessed the possible vascular sources of oxidative stress, including COX-1, COX-2, and nicotinamide adenine dinucleotide phosphate oxidase, as determinants of endothelial dysfunction in small arteries isolated from essential hypertensive patients or normotensive controls. Small arteries were dissected after subcutaneous fat biopsies and evaluated on a pressurized micromyograph. Endothelium-dependent vasodilation was assessed by acetylcholine, repeated under NG-nitro-l-arginine methyl ester, SC-560 (COX-1 inhibitor), DuP-697 (COX-2 inhibitor), ascorbic acid, or the nicotinamide adenine dinucleotide phosphate oxidase inhibitors apocynin or diphenylene iodonium. Vascular oxidative stress generation (fluorescent dihydroethidium), COX-1 and COX-2 expression (Western blot), and localization (immunohistochemistry) were also assessed. In controls, response to acetylcholine was blunted by NG-nitro-l-arginine methyl ester (P<0.001) and unmodified by SC-560, DuP-697, or ascorbic acid. In hypertensive patients, relaxation to acetylcholine was blunted, resistant to NG-nitro-l-arginine methyl ester or SC-560, and enhanced (P<0.01) by DuP-697, apocynin, or diphenylene iodonium (P<0.05). Furthermore, in hypertensive patients, response to acetylcholine was normalized by ascorbic acid or apocynin+DuP-697. Intravascular oxidative stress generation was enhanced in hypertensive patients, decreased (P<0.01) by DuP-697, partly attenuated by apocynin or diphenylene iodonium, and prevented by ascorbic acid. Enhanced COX-2 expression and localization in the vascular media of hypertensive patients were also detected. In small resistance arteries of essential hypertensive patients, COX-2 is overexpressed and reduces nitric oxide availability. COX-2 represents a major source of oxidative stress generation, whereas nicotinamide adenine dinucleotide phosphate oxidase plays a minor, but significant, role in promoting superoxide generation.

Tumoral EPAS1 (HIF2A) mutations explain sporadic pheochromocytoma and paraganglioma in the absence of erythrocytosis.

Pheochromocytomas (PCCs) and paragangliomas (PGLs) are chromaffin-cell tumors that arise from the adrenal medulla and extra-adrenal paraganglia, respectively. The dysfunction of genes involved in the cellular response to hypoxia, such as VHL, EGL nine homolog 1, and the succinate dehydrogenase (SDH) genes, leads to a direct abrogation of hypoxia inducible factor (HIF) degradation, resulting in a pseudo-hypoxic state implicated in PCC/PGL development. Recently, somatic post-zygotic mutations in EPAS1 (HIF2A) have been found in patients with multiple PGLs and congenital erythrocytosis. We assessed 41 PCCs/PGLs for mutations in EPAS1 and herein describe the clinical, molecular and genetic characteristics of the 7 patients found to carry somatic EPAS1 mutations; 4 presented with multiple PGLs (3 of them also had congenital erythrocytosis), whereas 3 were single sporadic PCC/PGL cases. Gene expression analysis of EPAS1-mutated tumors revealed similar mRNA EPAS1 levels to those found in SDH-gene- and VHL-mutated cases and a significant up-regulation of two hypoxia-induced genes (PCSK6 and GNA14). Interestingly, single nucleotide polymorphism array analysis revealed an exclusive gain of chromosome 2p in three EPAS1-mutated tumors. Furthermore, multiplex-PCR screening for small rearrangements detected a specific EPAS1 gain in another EPAS1-mutated tumor and in three non-EPAS1-mutated cases. The finding that EPAS1 is involved in the sporadic presentation of the disease not only increases the percentage of PCCs/PGLs with known driver mutations, but also highlights the relevance of studying other hypoxia-related genes in apparently sporadic tumors. Finally, the detection of a specific copy number alteration affecting chromosome 2p in EPAS1-mutated tumors may guide the genetic diagnosis of patients with this disease.