The clinical utility of circulating neuroendocrine gene transcript analysis in well-differentiated paragangliomas and pheochromocytomas.

CONTEXT: Paragangliomas and pheochromocytomas (PPGLs) exhibit variable malignancy, which is difficult to determine by histopathology, amine measurements or tissue genetic analyses. OBJECTIVE: To evaluate whether a 51-neuroendocrine gene blood analysis has clinical utility as a diagnostic and prognostic marker. DESIGN: Prospective cohort study. Well-differentiated PPGLs (n = 32), metastatic (n = 4); SDHx mutation (n = 25); 12 biochemically active, Lanreotide treated (n = 4). Nine patients had multiple sampling. Age- and gender-matched controls and GEP-NETs (comparators). METHODS: Circulating neuroendocrine tumor mRNA measured (qPCR) with multianalyte algorithmic analysis. Metabolic, epigenomic and proliferative genes as well as somatostatin receptor expression were assessed (averaged, normalized gene expression: mean ± s.e.m.). Amines were measured by HPLC and chromogranin A by ELISA. Analyses (2-tailed): Fisher's test, non-parametric (Mann-Whitney), receiver-operator curve (ROC) and multivariate analysis (MVA). All data are presented as mean ± s.e.m. RESULTS: PPGL were NETest positive (100%). All exhibited higher scores than controls (55 ± 5% vs 8 ± 1%, P = 0.0001), similar to GEP-NETs (47 ± 5%). ROC analysis area under curve was 0.98 for differentiating PPGLs/controls (cut-off for normal: 26.7%). Mutation status was not directly linked to NETest. Genetic and molecular clustering was associated (P < 0.04) with NETest scores. Metastatic (80 ± 9%) and multicentric (64 ± 9%) disease had significantly (P < 0.04) higher scores than localized disease (43 ± 7%). Progressive disease (PD) had the highest scores (86 ± 2%) vs stable (SD, 41 ± 2%) (P < 0.0001). The area under the curve for PD from SD was 0.93 (cut-off for PD: 53%). Proliferation, epigenetic and somatostatin receptor gene expression was elevated (P < 0.03) in PD. Metabolic gene expression was decreased in SDHx mutations. Repeat NETest measurements defined clinical status in the 9 patients (6 SD and 3 PD). Amine measurement was non-informative. Multivariate analysis identified NETest >53% as an independent prognostic factor. CONCLUSION: Circulating NET transcript analysis is positive (100% diagnostic) in well-differentiated PCC/PGL, scores were elevated in progressive disease irrespective of mutation or biochemical activity and elevated levels were prognostic.

Next-generation sequencing for diagnosis of thoracic aortic aneurysms and dissections: diagnostic yield, novel mutations and genotype phenotype correlations.

BACKGROUND: Thoracic aortic aneurysms and dissections (TAAD) are silent but possibly lethal condition with up to 40 % of cases being hereditary. Genetic background is heterogeneous. Recently next-generation sequencing enabled efficient and cost-effective examination of gene panels. Aim of the study was to define the diagnostic yield of NGS in the 51 TAAD patients and to look for genotype-phenotype correlations within families of the patients with TAAD. METHODS: 51 unrelated TAAD patients were examined by either whole exome sequencing or TruSight One sequencing panel. We analyzed rare variants in 10 established thoracic aortic aneurysms-associated genes. Whenever possible, we looked for co-segregation in the families. Kaplan-Meier survival curve was constructed to compare the event-free survival depending on genotype. Aortic events were defined as acute aortic dissection or first planned aortic surgery. RESULTS AND DISCUSSION: In 21 TAAD patients we found 22 rare variants, 6 (27.3 %) of these were previously reported, and 16 (73.7 %) were novel. Based on segregation data, functional analysis and software estimations we assumed that three of novel variants were causative, nine likely causative. Remaining four were classified as of unknown significance (2) and likely benign (2). In all, 9 (17.6 %) of 51 probands had a positive result when considering variants classified as causative only and 18 (35.3 %) if likely causative were also included. Genotype-positive probands (n = 18) showed shorter mean event free survival (41 years, CI 35-46) than reference group, i.e. those (n = 29) without any plausible variant identified (51 years, CI 45-57, p = 0.0083). This effect was also found when the 'genotype-positive' group was restricted to probands with 'likely causative' variants (p = 0.0092) which further supports pathogenicity of these variants. The mean event free survival was particularly low (37 years, CI 27-47) among the probands with defects in the TGF beta signaling (p = 0.0033 vs. the reference group). CONCLUSIONS: This study broadens the spectrum of genetic background of thoracic aneurysms and dissections and supports its potential role as a prognostic factor in the patients with the disease.

Cardiovascular Risk in Primary Hyperaldosteronism.

After the first cases of primary aldosteronism were described and characterized by Conn, a substantial body of experimental and clinical evidence about the long-term effects of excess aldosterone on the cardiovascular system was gathered over the last 5 decades. The prevalence of primary aldosteronism varies considerably between different studies among hypertensive patients, depending on patient selection, the used diagnostic methods, and the severity of hypertension. Prevalence rates vary from 4.6 to 16.6% in those studies in which confirmatory tests to diagnose primary aldosteronism were used. There is also growing evidence indicating that prolonged exposure to elevated aldosterone concentrations is associated with target organ damage in the heart, kidney, and arterial wall, and high cardiovascular risk in patients with primary aldosteronism. Therefore, the aim of treatment should not be confined to BP normalization and hypokalemia correction, but rather should focus on restoring the deleterious effects of excess aldosterone on the cardiovascular system. Current evidence convincingly demonstrates that both surgical and medical treatment strategies beneficially affect cardiovascular outcomes and mortality in the long term. Further studies can be expected to provide better insight into the relationship between cardiovascular risk and complications and the genetic background of primary aldosteronism.

Efficacy and safety of canagliflozin compared with placebo and sitagliptin in patients with type 2 diabetes on background metformin monotherapy: a randomised trial.

AIMS/HYPOTHESIS: The aim of this work was to evaluate the efficacy and safety of canagliflozin vs placebo and sitagliptin in patients with type 2 diabetes who were being treated with background metformin. METHODS: This randomised, double-blind, four-arm, parallel-group, Phase 3 study was conducted at 169 centres in 22 countries between April 2010 and August 2012. Participants (N = 1,284) with type 2 diabetes aged ≥ 18 and ≤ 80 years who had inadequate glycaemic control (HbA1c ≥ 7.0% [53 mmol/mol] and ≤10.5% [91 mmol/mol]) on metformin therapy received canagliflozin 100 mg or 300 mg, sitagliptin 100 mg, or placebo (n = 368, 367, 366, 183, respectively) for a 26 week, placebo- and active-controlled period followed by a 26 week, active-controlled period (placebo group switched to sitagliptin [placebo/sitagliptin]) and were included in the modified intent-to-treat analysis set. Randomisation was performed using a computer-generated schedule; participants, study centres and the sponsor were blinded to group assignment. The primary endpoint was change from baseline in HbA1c at week 26; secondary endpoints included changes in HbA1c (week 52) and fasting plasma glucose (FPG), body weight, and systolic blood pressure (BP; weeks 26 and 52). Adverse events (AEs) were recorded throughout the study. RESULTS: At week 26, canagliflozin 100 mg and 300 mg reduced HbA1c vs placebo (-0.79%, -0.94%, -0.17%, respectively; p < 0.001). At week 52, canagliflozin 100 mg and 300 mg demonstrated non-inferiority, and canagliflozin 300 mg demonstrated statistical superiority, to sitagliptin in lowering HbA1c (-0.73%, -0.88%,-0.73%, respectively); differences (95% CI) vs sitagliptin were 0% (-0.12, 0.12) and -0.15% (-0.27, -0.03), respectively. Canagliflozin 100 mg and 300 mg reduced body weight vs placebo (week 26: -3.7%, -4.2%, -1.2%, respectively; p < 0.001) and sitagliptin (week 52: -3.8%, -4.2%, -1.3%, respectively; p < 0.001). Both canagliflozin doses reduced FPG and systolic BP vs placebo (week 26) and sitagliptin (week 52) (p < 0.001). Overall AE and AE-related discontinuation rates were generally similar across groups, but higher with canagliflozin 100 mg. Genital mycotic infection and osmotic diuresis-related AE rates were higher with canagliflozin; few led to discontinuations. Hypoglycaemia incidence was higher with canagliflozin. CONCLUSIONS/INTERPRETATION: Canagliflozin improved glycaemia and reduced body weight vs placebo (week 26) and sitagliptin (week 52) and was generally well tolerated in patients with type 2 diabetes on metformin. CLINICAL TRIAL REGISTRY: ClinicalTrials.gov NCT01106677 FUNDING: This study was supported by Janssen Research & Development, LLC.

Clinical characteristics of patients with resistant hypertension: the RESIST-POL study.

Recent studies indicate that resistant hypertension (RHTN) is present in about 12% of the treated hypertensive population. However, patients with true RHTN (confirmed out of the office) have not been widely studied. We prospectively studied 204 patients (123 male, 81 female, mean age 48.4 years, range 19-65 years) with truly RHTN (ambulatory daytime mean blood pressure >135/85 mm Hg). We evaluated the frequency of obstructive sleep apnea (OSA), renal artery stenosis (RAS), primary aldosteronism (PA) and other secondary forms of hypertension (HTN) and conditions. Mild, moderate and severe OSA were present in 55 (27.0%), 38 (18.6%) and 54 (26.5%) patients, respectively. Secondary forms of HTN were diagnosed in 49 patients (24.0%), the most frequent being PA (15.7%) and RAS (5.4%). Metabolic syndrome (MS) was present in 65.7% of patients. Excessive sodium excretion was evident in 33.3% of patients and depression in 36.8% patients. In patients with RHTN, OSA and MS were the most frequent conditions, frequently overlapping with each other and also with PA. Our data indicate that in the vast majority of patients with truly RHTN, at least one of three co-morbidities-OSA, MS and PA-is present. Other conditions, even though less frequent, should also be taken into the consideration.

Mortality associated with phaeochromocytoma.

Two major categories of mortality are distinguished in patients with phaeochromocytoma. First, the effects of excessive circulating catecholamines may result in lethal complications if the disease is not diagnosed and/or treated timely. The second category of mortality is related to development of metastatic disease or other neoplasms. Improvements in disease recognition and diagnosis over the past few decades have reduced mortality from undiagnosed tumours. Nevertheless, many tumours remain unrecognised until they cause severe complications. Death resulting from unrecognised or untreated tumour is caused by cardiovascular complications. There are also numerous drugs and diagnostic or therapeutic manipulations that can cause fatal complications in patients with phaeochromocytoma. Previously it has been reported that operative mortality was as high as 50% in unprepared patients with phaeochromocytoma who were operated and in whom the diagnosis was unsuspected. Today mortality during surgery in medically prepared patients with the tumour is minimal. Phaeochromocytomas may be malignant at presentation or metastases may develop later, but both scenarios are associated with a potentially lethal outcome. Patients with phaeochromocytoma run an increased risk to develop other tumours, resulting in an increased mortality risk compared to the general population. Phaeochromocytoma during pregnancy represents a condition with potentially high maternal and foetal mortality. However, today phaeochromocytoma in pregnancy is recognised earlier and in conjunction with improved medical management, maternal mortality has decreased to less than 5%.

Long-term postoperative follow-up in patients with apparently benign pheochromocytoma and paraganglioma.

Patients with pheochromocytoma or paraganglioma are at risk of developing tumor recurrences or new tumors after successful resection of the primary tumor. This review summarizes current knowledge concerning the incidence and risk factors for such events. The overall incidence exceeds 15%. Patients with inherited tumors have a higher probability of recurrence or new tumors. Most recurrences are metastatic, particularly in patients with SDHB mutations or nonhereditary tumors. We recommend the determination of plasma or urinary metanephrines (normetanephrine and metanephrine) 1 month after surgery. In patients with sporadic, single tumors ≤5 cm in diameter, clinical and biochemical follow-up should be performed every 2 years. However, this follow-up period can be reduced to yearly, if it is more simple and more convenient for patients and physicians. Patients with larger or multiple but apparently benign tumors and/or inherited disease should be tested 6 months after surgery and then every year for the rest of their lives. Imaging follow-up is also required in patients with inherited or malignant tumors.

Office and ambulatory pulse pressure--association with clinical characteristics and cardiovascular risk factors in normoalbuminuric patients with type 2 diabetes (ROADMAP study).

To investigate the association of office and ambulatory 24-h pulse pressure (PP) with clinical characteristics and cardiovascular risk factors in normoalbuminuric type 2 diabetic patients enrolled to the Randomised Olmesartan and Diabetes Microalbuminuria Prevention study, 4449 patients (2054 male and 2395 female; mean age 57.7±8.7 years) with type 2 diabetes, normoalbuminuria and at least one additional cardiovascular risk factor were included into the analysis. After adjustment by age, there were significant correlations between office PP and presence of hypertension (r=0.24; P<0.001), presence of cardiac and vascular disorders (r=0.17; P<0.001), metabolic syndrome (r=0.10; P<0.001), duration of diabetes (r=0.09; P<0.001), fasting blood glucose (r=0.08; P<0.001), albumin/creatinine ratio (r=0.07; P<0.001), insulin treatment, glycosylated haemoglobin (HbA1c), male gender and current smoking. In the subgroup of 1234 patients with ambulatory blood pressure measurement performed, ambulatory PP adjusted for office PP correlated with fasting blood glucose (r=0.16; P<0.001), metabolic syndrome (r=0.14; P<0.001), albumin/creatinine ratio (r=0.11; P<0.001) and indices of glycemic control (HbA1c: r=0.11; P<0.001). In this group of normoalbuminuric type 2 diabetic patients, office and ambulatory PP were associated with duration of diabetes, indices of glycemic control and cardiovascular risk factors. There was relationship between office and ambulatory PP and albuminuria even within normal albuminuria range.

Pheochromocytoma-related 'classic' takotsubo cardiomyopathy.

We report a case of a 53-year-old hypertensive male with takotsubo cardiomyopathy in the setting of pheochromocytoma. Pheochromocytoma presenting as takotsubo cardiomyopathy is a recognized but uncommon occurrence with recently increasing number of published cases. We present typical apical ballooning syndrome, with transient left ventricular apical ballooning in contrast to several reports, in which patients with pheochromocytoma-induced cardiomyopathy had so called 'inverted'takotsubo cardiomyopathy. In patients being diagnosed with acute coronary syndrome symptoms without coronary artery stenosis or spasm, and pronounced blood pressure variability, pheochromocytoma-induced takotsubo or 'inverted' takotsubo cardiomyopathy should be kept in mind.

Determinants of urinary albumin excretion within the normal range in patients with type 2 diabetes: the Randomised Olmesartan and Diabetes Microalbuminuria Prevention (ROADMAP) study.

AIMS/HYPOTHESIS: In contrast to microalbuminuric type 2 diabetic patients, the factors correlated with urinary albumin excretion are less well known in normoalbuminuric patients. This may be important because even within the normoalbuminuric range, higher rates of albuminuria are known to be associated with higher renal and cardiovascular risk. METHODS: At the time of screening for the Randomised Olmesartan and Diabetes Microalbuminuria Prevention (ROADMAP) Study, the urinary albumin/creatinine ratio (UACR) was 0.44 mg/mmol in 4,449 type 2 diabetic patients. The independent correlates of UACR were analysed. RESULTS: Independent correlates of UACR during baseline were (in descending order): night-time systolic BP (r(s) = 0.19); HbA(1c) (r(s) = 0.18); mean 24 h systolic BP (r(s) = 0.16); fasting blood glucose (r(s) = 0.16); night-time diastolic BP (r(s) = 0.12); office systolic BP, sitting (r(s) = 0.11), standing (r(s) = 0.10); estimated GFR (r(s) = 0.10); heart rate, sitting (r(s) = 0.10); haemoglobin (r(s) = -0.10); triacylglycerol (r(s) = 0.09); and uric acid (r(s) = -0.08; all p

Renal artery aneurysms: presentation of five cases.

We are presenting clinical characteristics, management and follow-up of five consecutive patients with renal artery aneurysm. Renal artery aneurysms are relatively uncommon, they rarely give rise to clinical manifestations and they are usually found incidentally. However with the introduction of Doppler ultrasound, computed tomography (CT) and magnetic resonance (MR) imaging, the diagnosis of renal artery aneurysms became more frequent.

The genetic basis of pheochromocytoma.

Until very recently, the majority of hereditary pheochromocytomas were related to the MEN 2 and the VHL. In rare instances, hereditary pheochromocytoma was reported in patients with NF1. In addition, nonsyndromic hereditary pheochromocytomas have been reported. Recently, three more genes (SDHD, SDHB, and SDHC) which are all related subunits of the mitochondrial complex II have been identified to cause susceptibility to pheochromocytoma and/or paraganglioma. Hence, mutation analysis of VHL, RET, SDHB, and SDHD is generally recommended in patients with pheochromocytoma regardless of their family history or other features suggestive for a hereditary form. Mutation analysis should start with VHL and RET. However, in the presence of extra-adrenal pheochromocytoma, it may be more useful to screen for VHL, SDHD and SDHB mutations. It is of interest that various different genes can lead to one type of tumor formation. A common pathway (i.e. oxygen sensing) has been shown for VHL and SDHX. However, although several genes that are involved in the pathogenesis of hereditary pheochromocytoma are known, the precise molecular steps in tumorigenesis are widely unknown. In addition, recent data in MEN 2 pheochromocytomas point to a 'second hit' mechanism as a trigger for tumor formation. The molecular pathogenesis of sporadic pheochromocytomas remains obscure [114].

Genetic influence on blood pressure and lipid parameters in a sample of Polish twins.

We studied 76 healthy monozygotic (MZ) and same-sex dizygotic (DZ) twin pairs (mean age 35 +/- 8 years, body mass index, BMI, 23.6 +/- 3.9 kg/m2) to determine genetic and environmental contributions to systolic (SBP) and diastolic (DBP) blood pressure, heart rate (HR) and serum lipids [total cholesterol (TC), low-density lipoprotein cholesterol (LDL-chol), high-density lipoprotein cholesterol (HDL-chol) and triglycerides (TG)I. SBP, DBP and HR were measured clinically and by ambulatory blood pressure monitoring (ABPM). Parameters of the genetic models for age-, sex- and BMI-adjusted data were estimated by model fitting and path analysis technique using LISREL 8. We found significant genetic effect on SBP and DBP for both clinical and ABP measurements, ranging from 37% for night-time ambulatory DBP to 79% for daytime ambulatory SBP. Estimates of genetic effects were higher for daytime than night-time ABP values, and higher for ambulatory 24-h SBP than office SBP measurements, with the reverse true for DBP. Significant genetic effect on HR ranged from 59% for office measurements to 69% for 24-h mean values. In summary, we also found genetic effect on TC, LDL-chol and HDL-chol with estimates ranging from 36% to 64%, but not on TG. Furthermore, a shared environmental component for TG was found, estimated at 36%. We showed significant genetic effect on both office and ambulatory BP and HR, with stronger genetic effect on daytime than night-time BP. We also found genetic effect on TC and lipoprotein fractions, but no significant genetic effect on TG. Environmental factors influencing serum TG, such as alcohol consumption, may explain the apparent lack of genetic effect in this healthy, non-obese population.

Arteriovenous fistula of the kidney: a case report of 47-year-old female patient treated by embolisation.

Arteriovenous fistulas of the kidney are rare. They may be acquired, idiopathic or arise in congenital arteriovenous malformations. There are only few reports in the current literature describing the successful embolisation of idiopathic arteriovenous fistulas. We report a 47-year-old hypertensive female patient with a successfully embolised arteriovenous fistula. Diagnosis was made on the basis of colour duplex Doppler examination and this method enabled further successful embolisation of the fistula.

Dopamine and dopa urinary excretion in patients with pheochromocytoma--diagnostic implications.

Pheochromocytoma, a potentially life-threatening disease, is a rare cause of hypertension. Most pheochromocytomas secrete excessive amounts of noradrenaline and adrenaline. It has been suggested by some authors that high circulating levels of dopamine and the catecholamine precursor dihydroxyphenylalanine (dopa) are more often associated with malignant rather than benign pheochromocytomas. Therefore the aim of this study was to evaluate urinary excretion of dopamine and dopa in patients with pheochromocytoma and to determine their role as a potential marker for malignancy of the tumour. We retrospectively analysed 120 consecutive patients (mean age 41 +/- 12 years) with histopathologically confirmed pheochromocytomas. All subjects were divided as follows: group 1 included patients with both elevated and normal dopamine urinary excretion; group 2 was characterized by increased and normal dopa urinary excretion. Dopamine urinary excretion was increased in all patients with malignant pheochromocytoma, but higher levels were also observed in some patients with a benign tumour included in group 1. Urinary excretion of dopa was in the normal range in all subjects with malignant pheochromocytoma. The results indicate that in some pheochromocytoma patients excessive dopamine excretion may point to malignant tumour, but is not a discriminating marker for malignancy in the whole studied group.

Incidence and clinical relevance of RET proto-oncogene germline mutations in pheochromocytoma patients.

BACKGROUND: Autosomal dominant cancer syndrome--multiple endocrine neoplasia type 2 (MEN 2), may exist more often than expected in patients with pheochromocytoma. Germline mutations identified recently in MEN 2 can be revealed by genetic screening. OBJECTIVE: To evaluate the frequency of RET (rearranged during transfection) mutations in patients with pheochromocytoma. DESIGN AND METHODS: We genetically screened germline mutations in the RET proto-oncogene and clinically re-evaluated patients with pheochromocytoma. A pentagastrin test and other biochemical studies were performed in all patients. SETTING: Department of Internal Medicine and Hypertension, The Medical University of Warsaw, Warsaw, Poland and the Department of Nephrology and Hypertension, Albert Ludwigs University, Freiburg, Germany. PARTICIPANTS: Seventy seven unselected patients with pheochromocytoma (19 men, 58 women, mean age: 51.55 +/- 1.5 years; pheochromocytoma confirmed histopathologically) out of 162 diagnosed and treated in the years 1957-1998 in the Department of Internal Medicine and Hypertension in Warsaw, Poland. The other 85 patients did not respond to the written invitation. MAIN OUTCOME MEASURES: The finding of RET mutations and diagnosis of MEN 2 in patients with pheochromocytoma. RESULTS: Genetic testing revealed germline mutations in the RET proto-oncogene in six patients (7.8%). All carriers had mutation of exon 11, codon 634: TGC to CGC. In four patients with this mutation, medullary thyroid carcinoma (MIC) was diagnosed and in three cases, surgically treated. Biochemical parameters: parathormone 31.88 +/- 2.87 pg/ml, calcitonin: 0 min 0.23 +/- 0.14 ng/ml; 2 min 0.49 +/- 0.21 ng/ml; 5 min 0.48 +/- 0.21 ng/ml, metoxycatecholamines: 601.62 +/- 42.71 microg/24h, epinephrine: 1.94 +/- 0.17 microg/24h, norepinephrine 13.96 +/- 1.3 microg/24h, carcinoembryonic antigen (CEA) 9.94 +/- 4.3 ng/ml. Ambulatory blood pressure monitoring (ABPM): systolic blood pressure (SBP): 116 +/- 1.9 mmHg, diastolic blood pressure (DBP): 73.7 +/- 0.9 mmHg. Clinical, biochemical and imaging procedures did not reveal any recurrence of pheochromocytoma in the 77 patients studied. CONCLUSIONS: Patients with pheochromocytoma should be genetically screened for mutations of the RET proto-oncogene. These patients should undergo clinical screening for MEN 2. In addition, genetic studies can be useful for the screening of the families of the carriers.

Endothelin-1 inactivating peptidase in the human kidney and urine.

OBJECTIVE: Recently, an apparently novel, specific endothelin-1 inactivating metalloendopeptidase (ET-1 peptidase) has been isolated from the rat kidney. In this study we attempted to determine whether the same or a similar peptidase is present in the human kidney, and whether the enzyme is excreted into the urine. The urinary ET-1 peptidase could serve as an indirect index of the renal endothelin system, both in physiology and pathophysiology. METHODS: Kidney specimens were obtained from part of nephrectomized kidneys unaffected by any neoplastic process from six adult patients. The enzyme was purified using differential centrifugation, detergent solubilization of the membrane proteins, ultrafiltration and nondenaturing gel electrophoresis. The enzyme activity assays were performed at pH 5.5 and 37 degrees C in the presence of increasing concentrations of unlabelled peptides and inhibitors using a fixed amount of [125I]ET-1 as substrate. The degradation extent was quantified with trichloroacetic acid precipitation and high performance liquid chromatography. The degrading activity of ET-1 was determined in urine samples from adult patients with hypertension, children with chronic renal failure and those with stable renal allograft RESULTS: ET-1 peptidase from the human kidney displays characteristics close to that of the rat ET-1 peptidase we have recently described (J. Hypertens 1994; 12:1155-1162). The enzyme, a membrane-bound metalloendopeptidase, exhibits low electro- phoretical mobility on nondenaturing gel (Rf 0.08); it is an apparently heterologous structure comprising three enzymatically inactive subunits, it has a pH optimum at 5.5, a nanomolar range affinity to the ET-1 (KM 180 nmol/l) that is hydrolysed to two main degradation products, and a 10-100-fold lower affinity to big ET-1 (KM 11.5 micromol/l), endothelin 11 21 fragment (KM 15.3 micromol/l), endothelin antagonist Trp-Leu-Asp-Ile-Ile-Trp (KM 3.1 micromol/I), gastrin (KM 2.2 micromol/l) and cholecystokinin (KM 4.0 micromol/l). Substance P, neuropeptide Y, atrial natriuretic peptide, bradykinin, angiotensin II and enkephalin were poor substrates for the enzyme. The most powerful inhibitors of the ET-1 peptidase included thiorphan (IC50 0.28 nmol/l), phosphoramidon (IC50 0.55 nmol/l), phenanthroline (IC50 11.5 micromol/l), cyclosporin (IC50 400 micromol/l), phosphate (IC50 1.2 mmol/l), citrate (IC50 0.6 mmol/l) and aniline naphthalene sulphonic acid (IC50 0.25 mmol/l). Our data suggest that three ET-1 degrading peptidases with optimal activity at pH 4.5, 5.5 and 7.0, respectively, are excreted into the urine. The enzyme with a pH optimum 4.5 is of lysosomal origin whereas the two other enzymes correspond by their pH optima to the renal ET-1 peptidase and neutral endopeptidase. We have found statistically significant increases (P < 0.001) in the activity of both lysosomal and ET-1 peptidase in the urine in patients with hypertension and in children with chronic renal failure compared with healthy subjects or children with stable renal allograft CONCLUSIONS: Human kidney contains an acidic, highly specific endothelin-1 inactivating metalloendopeptidase that may have a key role in the regulation of concentrations of renal and circulating endothelins. The enzyme is excreted into the urine where its activity seems to be increased in patients with hypertension and chronic renal failure; it may potentially serve as an indirect index of the renal endothelin system.

Discriminatory power of MRI for differentiation of adrenal non-adenomas vs adenomas evaluated by means of ROC analysis: can biopsy be obviated?

The purpose of our study was to evaluate the discriminatory power of MRI in high-field magnet (1.5 T) for differentiation of adrenal non-adenomas vs adenomas assessing the following parameters separately and in combination: mean diameter of adrenal mass; previously described and new ratios as well as index calculated from signal intensity (SI) on SE T2-weighted images, chemical shift imaging (CSI), and Gd-DTPA-enhanced dynamic studies. One hundred eight adrenal masses (36 non-hyperfunctioning adenomas, 27 pheochromocytomas, 23 aldosterone-secreting adenomas, 20 malignant masses and 2 cortisol-secreting adenomas) in 95 patients were evaluated with SE sequences, CSI and Gd-DTPA dynamic studies. Indices and ratios of SI for all examined MRI methods were calculated and examined retrospectively for significance of differences between the groups with calculation of sensitivity and specificity. Receiver operating characteristics (ROC) analysis of calculated parameters in combination was performed. The multifactorial analysis of all four parameters, including size of the tumor, T2(liver) index, CSI ratio reflecting lipid content in the tumor and Wo(max/last) ratio reflecting maximal washout of contrast agent from the tumor had 100 % sensitivity and 100 % specificity in characterization of adrenal non-adenoma. The best performance of combination of mean tumor diameter with single MRI SI parameter was achieved in combination with T2(liver) index for all adrenal masses (area under ROC 0.987) and CSI ratio for non-hyperfunctioning adrenal masses (area under ROC 0.991). Magnetic resonance imaging enables sensitive and specific diagnosis of adrenal non-adenoma.