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Abstract
Hypertension is a common condition affecting one in four adults. It is a leading cause of cardiovascular morbidity and mortality and appropriate treatment strategies that are both clinically and cost effective are key to the management of this condition. Recent guidelines have focused on addressing total cardiovascular risk and recommended rational combinations of antihypertensives as well as highlighting the importance of lifestyle intervention. Recent advances have increased understanding of the pathogenesis of hypertension and have opened the possibility of novel interventions for treatment.
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Affiliation(s)
- F McManus
- MRC Blood Pressure Group, Glasgow Cardiovascular Research Centre, Western Infirmary, Glasgow. G11 6NT
| | - EM Freel
- MRC Blood Pressure Group, Glasgow Cardiovascular Research Centre, Western Infirmary, Glasgow. G11 6NT
| | - JMC Connell
- MRC Blood Pressure Group, Glasgow Cardiovascular Research Centre, Western Infirmary, Glasgow. G11 6NT
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2
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Mooij CF, Parajes S, Rose IT, Taylor AE, Bayraktaroglu T, Wass JAH, Connell JMC, Ray DW, Arlt W, Krone N. Characterization of the molecular genetic pathology in patients with 11β-hydroxylase deficiency. Clin Endocrinol (Oxf) 2015; 83:629-35. [PMID: 26053152 DOI: 10.1111/cen.12834] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Revised: 02/25/2015] [Accepted: 03/09/2015] [Indexed: 11/29/2022]
Abstract
OBJECTIVE Steroid 11β-hydroxylase (CYP11B1) deficiency (11OHD) is the second most common form of congenital adrenal hyperplasia. Nonclassic or mild 11OHD appears to be a rare condition. Our study assessed the residual CYP11B1 function of detected mutations, adding to the spectrum of mild 11OHD, and illustrates the variability of the clinical presentation of 11OHD. PATIENTS AND METHODS Five patients presented with mild to moderate 11OHD. Two women presented with mild hirsutism and in one case with secondary amenorrhoea. Two men presented with precocious pseudopuberty, gynaecomastia and elevated blood pressure. One 46,XX female patient was diagnosed with virilization of the external genitalia 2 years after birth. Direct DNA sequencing was carried out to perform CYP11B1 mutation analysis. The CYP11B1 mutations were functionally characterized using an in vitro expression system. RESULTS CYP11B1-inactivating mutations were detected in all patients. Two novel missense mutations (p.P42L and p.A297V) and the previously characterized p.R143W mutation had residual CYP11B1 activities between 10% and 27%. A novel p.L382R and the previously uncharacterized p.G444D mutation both caused complete loss of CYP11B1 enzymatic activity. CONCLUSION Mutations causing partial impairment of 11β-hydroxylase activity (residual activity of 10% or above) are associated with a less severe clinical presentation of 11OHD, which can be classified as a nonclassic form. Our data demonstrate that patients with nonclassic 11OHD can present with androgen excess, precocious pseudopuberty and increased blood pressure. Timely diagnosis of nonclassic 11OHD and consequently initiation of personalized treatment is essential to prevent co-morbidities caused by androgen excess and hypertension.
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Affiliation(s)
- Christiaan F Mooij
- Centre for Endocrinology, Diabetes, and Metabolism, School of Clinical and Experimental Medicine, University of Birmingham, Birmingham, UK
- Department of Pediatric Endocrinology, Amalia Children's Hospital, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Silvia Parajes
- Centre for Endocrinology, Diabetes, and Metabolism, School of Clinical and Experimental Medicine, University of Birmingham, Birmingham, UK
| | - Ian T Rose
- Centre for Endocrinology, Diabetes, and Metabolism, School of Clinical and Experimental Medicine, University of Birmingham, Birmingham, UK
| | - Angela E Taylor
- Centre for Endocrinology, Diabetes, and Metabolism, School of Clinical and Experimental Medicine, University of Birmingham, Birmingham, UK
| | - Taner Bayraktaroglu
- Division of Endocrinology, Department of Internal Medicine, Bulent Ecevıt University, Zonguldak, Turkey
| | - John A H Wass
- Department of Endocrinology, Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, Oxford, UK
| | - John M C Connell
- School of Medicine, Ninewells Hospital and Medical School, University of Dundee, Dundee, UK
| | - David W Ray
- Endocrine Sciences Research Group, University of Manchester, Manchester, UK
| | - Wiebke Arlt
- Centre for Endocrinology, Diabetes, and Metabolism, School of Clinical and Experimental Medicine, University of Birmingham, Birmingham, UK
| | - Nils Krone
- Centre for Endocrinology, Diabetes, and Metabolism, School of Clinical and Experimental Medicine, University of Birmingham, Birmingham, UK
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3
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Abstract
The importance of corticosteroids in cardiovascular and other chronic disease is recognised. In addition, plasma steroid precursor-to-product ratios are useful and convenient indirect indicators of efficiency of key steroidogenic enzymes (aldosterone synthase, 11β-hydroxylase and 17α-hydroxylase). The use of liquid chromatography-tandem mass spectrometry (LC-MS/MS) has enabled measurement of numerous corticosteroid compounds simultaneously. However, normal responses to trophins and variation in salt intake are not well described. This study examined these parameters in a large group of healthy volunteers. Sixty normotensive volunteers were recruited and underwent infusion of angiotensin II (AngII) and ACTH, following low- and high-salt diet. Measurement of plasma steroids at baseline and 30 min after infusion of trophin was carried out by LC-MS. As expected, plasma mineralocorticoid levels increased in response to salt restriction and were suppressed with salt loading; ACTH infusion increased all corticosteroids, while AngII increased mineralocorticoids and suppressed glucocorticoid production. ACTH increased S:F but decreased DOC:B, thus the S:F ratio is a more appropriate index of 11β-hydroxylase efficiency. The B:F ratio increased following ACTH treatment and salt restriction. A larger proportion of plasma B than generally accepted may be derived from the zona glomerulosa and this ratio may be most informative of 17α-hydroxylase activity in salt-replete subjects. Although DOC:aldosterone, B:aldosterone and 18-hydroxyB:aldosterone should provide indices of aldosterone synthase efficiency, responses of individual compounds to trophins suggest that none of them accurately reflect this. Based on these data, aldosterone synthase activity is most accurately reflected by aldosterone concentration alone.
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Affiliation(s)
- F McManus
- Institute of Cardiovascular and Medical SciencesUniversity of Glasgow, Glasgow Cardiovascular Research Centre, 126 University Place, Glasgow G12 8TA, UKCollege of MedicineDentistry and Nursing, Ninewells Hospital and Medical School, University of Dundee, Dundee DD1 9SY, UK
| | - R Fraser
- Institute of Cardiovascular and Medical SciencesUniversity of Glasgow, Glasgow Cardiovascular Research Centre, 126 University Place, Glasgow G12 8TA, UKCollege of MedicineDentistry and Nursing, Ninewells Hospital and Medical School, University of Dundee, Dundee DD1 9SY, UK
| | - E Davies
- Institute of Cardiovascular and Medical SciencesUniversity of Glasgow, Glasgow Cardiovascular Research Centre, 126 University Place, Glasgow G12 8TA, UKCollege of MedicineDentistry and Nursing, Ninewells Hospital and Medical School, University of Dundee, Dundee DD1 9SY, UK
| | - J M C Connell
- Institute of Cardiovascular and Medical SciencesUniversity of Glasgow, Glasgow Cardiovascular Research Centre, 126 University Place, Glasgow G12 8TA, UKCollege of MedicineDentistry and Nursing, Ninewells Hospital and Medical School, University of Dundee, Dundee DD1 9SY, UK
| | - E M Freel
- Institute of Cardiovascular and Medical SciencesUniversity of Glasgow, Glasgow Cardiovascular Research Centre, 126 University Place, Glasgow G12 8TA, UKCollege of MedicineDentistry and Nursing, Ninewells Hospital and Medical School, University of Dundee, Dundee DD1 9SY, UK
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4
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Terao C, Bayoumi N, McKenzie CA, Zelenika D, Muro S, Mishima M, Connell JMC, Vickers MA, Lathrop GM, Farrall M, Matsuda F, Keavney BD. Quantitative Variation in Plasma Angiotensin-I Converting Enzyme Activity Shows Allelic Heterogeneity in theABOBlood Group Locus. Ann Hum Genet 2013; 77:465-71. [DOI: 10.1111/ahg.12034] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2013] [Accepted: 05/16/2013] [Indexed: 12/20/2022]
Affiliation(s)
- Chikashi Terao
- The Center for Genomic Medicine; Kyoto University Graduate School of Medicine; Kyoto Japan
| | - Nervana Bayoumi
- Physiology Department, College of Medicine; King Saud University; Riyadh Saudi Arabia
| | - Colin A. McKenzie
- Tropical Metabolism Research Unit; University of the West Indies; Mona Jamaica
| | - Diana Zelenika
- Commisariat à l’énergie Atomique (CEA), Institut Genomique; Centre National de Genotypage; Evry France
- Fondation Jean Dausset; Centre d'Etude du Polymorphisme Humain; Paris France
| | - Shigeo Muro
- Department of Respiratory Medicine; Kyoto University Graduate School of Medicine; Kyoto Japan
| | - Michiaki Mishima
- Department of Respiratory Medicine; Kyoto University Graduate School of Medicine; Kyoto Japan
| | - John M C Connell
- College of Medicine, Dentistry and Nursing; University of Dundee; UK
| | | | - G. Mark Lathrop
- Commisariat à l’énergie Atomique (CEA), Institut Genomique; Centre National de Genotypage; Evry France
- Fondation Jean Dausset; Centre d'Etude du Polymorphisme Humain; Paris France
- McGill University and Genome Quebec Innovation Center; Montreal Canada
| | - Martin Farrall
- Division of Cardiovascular Medicine, Radcliffe Department of Medicine; University of Oxford; Oxford UK
- Wellcome Trust Centre for Human Genetics; University of Oxford; Oxford UK
| | - Fumihiko Matsuda
- The Center for Genomic Medicine; Kyoto University Graduate School of Medicine; Kyoto Japan
| | - Bernard D. Keavney
- Institute of Genetic Medicine; Newcastle University; UK
- Institute of Cardiovascular Sciences; Manchester University; UK
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5
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Abstract
Advances in the sensitivity of molecular techniques during the 1990s led to a flurry of studies that supported the existence of extra-adrenal sites of aldosterone production in various tissues including the brain and the heart. Subsequent work was often conflicting or ambiguous, leading many to question whether extra-adrenal aldosterone was of any physiological importance, or whether it even existed. In this article, we review these studies and, in light of this evidence, discuss whether the current lack of interest in extra-adrenal aldosterone biosynthesis is justified.
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Affiliation(s)
- Scott M MacKenzie
- Institute of Cardiovascular and Medical Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom.
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Kohlhaas CF, Morrow VA, Jhakra N, Patil V, Connell JMC, Petrie JR, Salt IP. Insulin rapidly stimulates L-arginine transport in human aortic endothelial cells via Akt. Biochem Biophys Res Commun 2011; 412:747-51. [PMID: 21871446 PMCID: PMC3257429 DOI: 10.1016/j.bbrc.2011.08.048] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2011] [Accepted: 08/09/2011] [Indexed: 01/04/2023]
Abstract
Insulin stimulates endothelial NO synthesis, at least in part mediated by phosphorylation and activation of endothelial NO synthase at Ser1177 and Ser615 by Akt. We have previously demonstrated that insulin-stimulated NO synthesis is inhibited under high culture glucose conditions, without altering Ca(2+)-stimulated NO synthesis or insulin-stimulated phosphorylation of eNOS. This indicates that stimulation of endothelial NO synthase phosphorylation may be required, yet not sufficient, for insulin-stimulated nitric oxide synthesis. In the current study we investigated the role of supply of the eNOS substrate, L-arginine as a candidate parallel mechanism underlying insulin-stimulated NO synthesis in cultured human aortic endothelial cells. Insulin rapidly stimulated L-arginine transport, an effect abrogated by incubation with inhibitors of phosphatidylinositol-3'-kinase or infection with adenoviruses expressing a dominant negative mutant Akt. Furthermore, supplementation of endothelial cells with extracellular L-arginine enhanced insulin-stimulated NO synthesis, an effect reversed by co-incubation with the L-arginine transport inhibitor, L-lysine. Basal L-arginine transport was significantly increased under high glucose culture conditions, yet insulin-stimulated L-arginine transport remained unaltered. The increase in L-arginine transport elicited by high glucose was independent of the expression of the cationic amino acid transporters, hCAT1 and hCAT2 and not associated with any changes in the activity of ERK1/2, Akt or protein kinase C (PKC). We propose that rapid stimulation of L-arginine transport contributes to insulin-stimulated NO synthesis in human endothelial cells, yet attenuation of this is unlikely to underlie the inhibition of insulin-stimulated NO synthesis under high glucose conditions.
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Affiliation(s)
- Christine F Kohlhaas
- Institute of Cardiovascular and Medical Sciences, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
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Rahman TJ, Walker EA, Mayosi BM, Hall DH, Avery PJ, Connell JMC, Watkins H, Stewart PM, Keavney B. Genotype at the P554L variant of the hexose-6 phosphate dehydrogenase gene is associated with carotid intima-medial thickness. PLoS One 2011; 6:e23248. [PMID: 21858044 PMCID: PMC3155541 DOI: 10.1371/journal.pone.0023248] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2011] [Accepted: 07/11/2011] [Indexed: 02/04/2023] Open
Abstract
OBJECTIVE The combined thickness of the intima and media of the carotid artery (carotid intima-medial thickness, CIMT) is associated with cardiovascular disease and stroke. Previous studies indicate that carotid intima-medial thickness is a significantly heritable phenotype, but the responsible genes are largely unknown. Hexose-6 phosphate dehydrogenase (H6PDH) is a microsomal enzyme whose activity regulates corticosteroid metabolism in the liver and adipose tissue; variability in measures of corticosteroid metabolism within the normal range have been associated with risk factors for cardiovascular disease. We performed a genetic association study in 854 members of 224 families to assess the relationship between polymorphisms in the gene coding for hexose-6 phosphate dehydrogenase (H6PD) and carotid intima-medial thickness. METHODS Families were ascertained via a hypertensive proband. CIMT was measured using B-mode ultrasound. Single nucleotide polymorphisms (SNPs) tagging common variation in the H6PD gene were genotyped. Association was assessed following adjustment for significant covariates including "classical" cardiovascular risk factors. Functional studies to determine the effect of particular SNPs on H6PDH were performed. RESULTS There was evidence of association between the single nucleotide polymorphism rs17368528 in exon five of the H6PD gene, which encodes an amino-acid change from proline to leucine in the H6PDH protein, and mean carotid intima-medial thickness (p = 0.00065). Genotype was associated with a 5% (or 0.04 mm) higher mean carotid intima-medial thickness measurement per allele, and determined 2% of the population variability in the phenotype. CONCLUSIONS Our results suggest a novel role for the H6PD gene in atherosclerosis susceptibility.
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Affiliation(s)
- Thahira J. Rahman
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Elizabeth A. Walker
- Department of Medicine, University of Birmingham, Birmingham, United Kingdom
| | - Bongani M. Mayosi
- Department of Medicine, University of Cape Town, Cape Town, South Africa
| | - Darroch H. Hall
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Peter J. Avery
- School of Mathematics and Statistics, Newcastle University, Newcastle upon Tyne, United Kingdom
| | | | - Hugh Watkins
- Department of Cardiovascular Medicine, Oxford University, Oxford, United Kingdom
| | - Paul M. Stewart
- Department of Medicine, University of Birmingham, Birmingham, United Kingdom
| | - Bernard Keavney
- Institute of Genetic Medicine, Newcastle University, Newcastle upon Tyne, United Kingdom
- * E-mail:
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Boyle JG, Logan PJ, Jones GC, Small M, Sattar N, Connell JMC, Cleland SJ, Salt IP. AMP-activated protein kinase is activated in adipose tissue of individuals with type 2 diabetes treated with metformin: a randomised glycaemia-controlled crossover study. Diabetologia 2011; 54:1799-809. [PMID: 21455728 DOI: 10.1007/s00125-011-2126-4] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/17/2011] [Accepted: 02/24/2011] [Indexed: 12/20/2022]
Abstract
AIMS/HYPOTHESIS The hypoglycaemic actions of metformin have been proposed to be mediated by hepatic AMP-activated protein kinase (AMPK). As the effects of metformin and the role of AMPK in adipose tissue remain poorly characterised, we examined the effect of metformin on AMPK activity in adipose tissue of individuals with type 2 diabetes in a randomised glycaemia-controlled crossover study. METHODS Twenty men with type 2 diabetes (aged 50-70 years) treated with diet, metformin or sulfonylurea alone were recruited from North Glasgow University National Health Service Trusts' diabetes clinics and randomised to either metformin or gliclazide for 10 weeks. Randomisation codes, generated by computer, were put into sealed envelopes and stored by the hospital pharmacist. Medication bottles were numbered, and allocation was done in sequence. The participants and investigators were blinded to group assignment. At the end of each phase of therapy adipose biopsy, AMPK activity (primary endpoint) and levels of lipid metabolism and signalling proteins were assessed. In parallel, the effect of metformin on AMPK and insulin-signalling pathways was investigated in 3T3-L1 adipocytes. RESULTS Ten participants were initially randomised to metformin and subsequently crossed over to gliclazide, while ten participants were initially randomised to gliclazide and subsequently crossed over to metformin. No participants discontinued the intervention and the adipose tissue AMPK activity was analysed in all 20 participants. There were no adverse events or side effects in the study group. Adipose AMPK activity was increased following metformin compared with gliclazide therapy (0.057 ± 0.007 vs 0.030 ± 0.005 [mean ± SEM] nmol min(-1) [mg lysate](-1); p < 0.005), independent of AMPK level, glycaemia or plasma adiponectin concentrations. The increase was associated with reduced levels of acetyl-CoA carboxylase (ACC) protein and increased ACC Ser80 phosphorylation. In 3T3-L1 adipocytes, metformin reduced levels of ACC protein and stimulated phosphorylation of AMPK Thr172 and hormone-sensitive lipase Ser565. CONCLUSIONS These results provide the first evidence that metformin activates AMPK and reduces ACC protein levels in human adipose tissue in vivo. Future studies are required to assess the role of adipose AMPK activation in the pharmacological effects of metformin. TRIAL REGISTRATION ISRCTN51336867.
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Affiliation(s)
- J G Boyle
- Institute of Cardiovascular and Medical Sciences, College of Medicine, Veterinary and Life Sciences, Davidson Building, University of Glasgow, Glasgow, G12 8QQ, UK
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Arlt W, Willis DS, Wild SH, Krone N, Doherty EJ, Hahner S, Han TS, Carroll PV, Conway GS, Rees DA, Stimson RH, Walker BR, Connell JMC, Ross RJ. Health status of adults with congenital adrenal hyperplasia: a cohort study of 203 patients. J Clin Endocrinol Metab 2010; 95:5110-21. [PMID: 20719839 PMCID: PMC3066446 DOI: 10.1210/jc.2010-0917] [Citation(s) in RCA: 292] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
CONTEXT No consensus exists for management of adults with congenital adrenal hyperplasia (CAH) due to a paucity of data from cohorts of meaningful size. OBJECTIVE Our objective was to establish the health status of adults with CAH. DESIGN AND SETTING We conducted a prospective cross-sectional study of adults with CAH attending specialized endocrine centers across the United Kingdom. PATIENTS Participants included 203 CAH patients (199 with 21-hydroxylase deficiency): 138 women, 65 men, median age 34 (range 18-69) years. MAIN OUTCOME MEASURES Anthropometric, metabolic, and subjective health status was evaluated. Anthropometric measurements were compared with Health Survey for England data, and psychometric data were compared with appropriate reference cohorts. RESULTS Glucocorticoid treatment consisted of hydrocortisone (26%), prednisolone (43%), dexamethasone (19%), or a combination (10%), with reverse circadian administration in 41% of patients. Control of androgens was highly variable with a normal serum androstenedione found in only 36% of patients, whereas 38% had suppressed levels suggesting glucocorticoid overtreatment. In comparison with Health Survey for England participants, CAH patients were significantly shorter and had a higher body mass index, and women with classic CAH had increased diastolic blood pressure. Metabolic abnormalities were common, including obesity (41%), hypercholesterolemia (46%), insulin resistance (29%), osteopenia (40%), and osteoporosis (7%). Subjective health status was significantly impaired and fertility compromised. CONCLUSIONS Currently, a minority of adult United Kingdom CAH patients appear to be under endocrine specialist care. In the patients studied, glucocorticoid replacement was generally nonphysiological, and androgen levels were poorly controlled. This was associated with an adverse metabolic profile and impaired fertility and quality of life. Improvements in the clinical management of adults with CAH are required.
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Affiliation(s)
- Wiebke Arlt
- Centre for Endocrinology, Diabetes, and Metabolism, School of Clinical and Experimental Medicine, University of Birmingham, Birmingham, United Kingdom
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10
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Padmanabhan S, Melander O, Johnson T, Di Blasio AM, Lee WK, Gentilini D, Hastie CE, Menni C, Monti MC, Delles C, Laing S, Corso B, Navis G, Kwakernaak AJ, van der Harst P, Bochud M, Maillard M, Burnier M, Hedner T, Kjeldsen S, Wahlstrand B, Sjögren M, Fava C, Montagnana M, Danese E, Torffvit O, Hedblad B, Snieder H, Connell JMC, Brown M, Samani NJ, Farrall M, Cesana G, Mancia G, Signorini S, Grassi G, Eyheramendy S, Wichmann HE, Laan M, Strachan DP, Sever P, Shields DC, Stanton A, Vollenweider P, Teumer A, Völzke H, Rettig R, Newton-Cheh C, Arora P, Zhang F, Soranzo N, Spector TD, Lucas G, Kathiresan S, Siscovick DS, Luan J, Loos RJF, Wareham NJ, Penninx BW, Nolte IM, McBride M, Miller WH, Nicklin SA, Baker AH, Graham D, McDonald RA, Pell JP, Sattar N, Welsh P, Munroe P, Caulfield MJ, Zanchetti A, Dominiczak AF. Genome-wide association study of blood pressure extremes identifies variant near UMOD associated with hypertension. PLoS Genet 2010; 6:e1001177. [PMID: 21082022 PMCID: PMC2965757 DOI: 10.1371/journal.pgen.1001177] [Citation(s) in RCA: 258] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2010] [Accepted: 09/23/2010] [Indexed: 12/19/2022] Open
Abstract
Hypertension is a heritable and major contributor to the global burden of disease. The sum of rare and common genetic variants robustly identified so far explain only 1%–2% of the population variation in BP and hypertension. This suggests the existence of more undiscovered common variants. We conducted a genome-wide association study in 1,621 hypertensive cases and 1,699 controls and follow-up validation analyses in 19,845 cases and 16,541 controls using an extreme case-control design. We identified a locus on chromosome 16 in the 5′ region of Uromodulin (UMOD; rs13333226, combined P value of 3.6×10−11). The minor G allele is associated with a lower risk of hypertension (OR [95%CI]: 0.87 [0.84–0.91]), reduced urinary uromodulin excretion, better renal function; and each copy of the G allele is associated with a 7.7% reduction in risk of CVD events after adjusting for age, sex, BMI, and smoking status (H.R. = 0.923, 95% CI 0.860–0.991; p = 0.027). In a subset of 13,446 individuals with estimated glomerular filtration rate (eGFR) measurements, we show that rs13333226 is independently associated with hypertension (unadjusted for eGFR: 0.89 [0.83–0.96], p = 0.004; after eGFR adjustment: 0.89 [0.83–0.96], p = 0.003). In clinical functional studies, we also consistently show the minor G allele is associated with lower urinary uromodulin excretion. The exclusive expression of uromodulin in the thick portion of the ascending limb of Henle suggests a putative role of this variant in hypertension through an effect on sodium homeostasis. The newly discovered UMOD locus for hypertension has the potential to give new insights into the role of uromodulin in BP regulation and to identify novel drugable targets for reducing cardiovascular risk. Hypertension is the leading contributor to global mortality with a global prevalence of 26.4% in 2000, projected to increase to 29.2% by 2025. While 50%–60% of population variation in blood pressure can be attributable to additive genetic factors, all the genetic variants robustly identified so far explain only 1%–2% of the population variance indicating the presence of additional undiscovered risk variants. Using an extreme case-control strategy, we have discovered a SNP in the promoter region of the uromodulin gene (UMOD) to be associated with hypertension (minor allele protective against hypertension). We then validated this association using large-scale population and case-control studies, where similar extreme criteria for selection of cases and controls have been used (21,466 cases and 18,240 controls). As the locus was related to uromodulin, a protein exclusively expressed in the kidneys, we show that the association is independent of renal dysfunction. We also show preliminary evidence that the SNP allele which is protective against hypertension is also protective against cardiovascular events in 26,654 Swedish subjects followed-up for 12 years. The newly discovered UMOD locus for hypertension has the potential to give unique insights into the role of uromodulin in BP regulation and to identify novel drugable targets.
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Affiliation(s)
- Sandosh Padmanabhan
- Institute of Cardiovascular and Medical Sciences, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Olle Melander
- Department of Clinical Sciences, Hypertension and Cardiovascular Diseases, University Hospital Malmö, Lund University, Malmö, Sweden
| | - Toby Johnson
- Clinical Pharmacology and Barts and the London Genome Centre, William Harvey Research Institute, Barts and the London School of Medicine, Queen Mary University of London, London, United Kingdom
| | | | - Wai K. Lee
- Institute of Cardiovascular and Medical Sciences, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | | | - Claire E. Hastie
- Institute of Cardiovascular and Medical Sciences, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Cristina Menni
- Institute of Cardiovascular and Medical Sciences, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
- Università Milano-Bicocca, Dipartimento di Medicina Clinica e Prevenzione, Ospedale San Gerardo, Monza, Milano, Italy
| | - Maria Cristina Monti
- Istituto Auxologico Italiano, Milan, Italy
- Department of Health Science, University of Pavia, Pavia, Italy
| | - Christian Delles
- Institute of Cardiovascular and Medical Sciences, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Stewart Laing
- Institute of Cardiovascular and Medical Sciences, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Barbara Corso
- Istituto Auxologico Italiano, Milan, Italy
- Department of Health Science, University of Pavia, Pavia, Italy
| | - Gerjan Navis
- Department of Nephrology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Arjan J. Kwakernaak
- Department of Nephrology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Pim van der Harst
- Department of Cardiology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Murielle Bochud
- University Institute of Social and Preventive Medicine, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland
| | - Marc Maillard
- Service of Nephrology, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland
| | - Michel Burnier
- Service of Nephrology, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland
| | - Thomas Hedner
- Institute of Medicine, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Sverre Kjeldsen
- Department of Cardiology, University of Oslo, Ullevaal Hospital, Oslo, Norway
| | - Björn Wahlstrand
- Institute of Medicine, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Marketa Sjögren
- Department of Clinical Sciences, Hypertension and Cardiovascular Diseases, University Hospital Malmö, Lund University, Malmö, Sweden
| | - Cristiano Fava
- Department of Clinical Sciences, Hypertension and Cardiovascular Diseases, University Hospital Malmö, Lund University, Malmö, Sweden
- Department of Medicine, Section of Internal Medicine C, University of Verona, Verona, Italy
| | - Martina Montagnana
- Department of Clinical Sciences, Hypertension and Cardiovascular Diseases, University Hospital Malmö, Lund University, Malmö, Sweden
- Department of Life and Reproduction Sciences, Section of Clinical Chemistry, University of Verona, Verona, Italy
| | - Elisa Danese
- Department of Clinical Sciences, Hypertension and Cardiovascular Diseases, University Hospital Malmö, Lund University, Malmö, Sweden
- Department of Life and Reproduction Sciences, Section of Clinical Chemistry, University of Verona, Verona, Italy
| | - Ole Torffvit
- Department of Nephrology, Institution of Clinical Sciences, University Hospital of Lund, Lund, Sweden
| | - Bo Hedblad
- Department of Clinical Sciences, Hypertension and Cardiovascular Diseases, University Hospital Malmö, Lund University, Malmö, Sweden
| | - Harold Snieder
- Unit of Genetic Epidemiology and Bioinformatics, Department of Epidemiology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - John M. C. Connell
- College of Medicine, Dentistry and Nursing, Ninewells Hospital, University of Dundee, Dundee, United Kingdom
| | - Morris Brown
- Clinical Pharmacology Unit, University of Cambridge, Addenbrookes Hospital, Cambridge, United Kingdom
| | - Nilesh J. Samani
- Department of Cardiovascular Sciences, University of Leicester, Glenfield Hospital, Leicester, United Kingdom
| | - Martin Farrall
- Department of Cardiovascular Medicine, Wellcome Trust Centre for Human Genetics, Oxford, United Kingdom
| | - Giancarlo Cesana
- Università Milano-Bicocca, Dipartimento di Medicina Clinica e Prevenzione, Ospedale San Gerardo, Monza, Milano, Italy
| | - Giuseppe Mancia
- Università Milano-Bicocca, Dipartimento di Medicina Clinica e Prevenzione, Ospedale San Gerardo, Monza, Milano, Italy
| | | | - Guido Grassi
- Università Milano-Bicocca, Dipartimento di Medicina Clinica e Prevenzione, Ospedale San Gerardo, Monza, Milano, Italy
| | - Susana Eyheramendy
- Department of Statistics, Pontificia Universidad Catolica de Chile, Santiago, Chile
| | - H. Erich Wichmann
- Institute of Epidemiology, Helmholtz Zentrum München, German Research Center for Environmental Health, Neuherberg, Germany
- Institute of Medical Informatics, Biometry and Epidemiology, Chair of Epidemiology, Ludwig-Maximilians-Universität, Munich, Germany
| | - Maris Laan
- Institute of Molecular and Cell Biology, University of Tartu, Tartu, Estonia
| | - David P. Strachan
- Division of Community Health Sciences, St George's, University of London, London, United Kingdom
| | - Peter Sever
- International Centre for Circulatory Health National Heart and Lung Institute, Imperial College, London, United Kingdom
| | - Denis Colm Shields
- Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Dublin, Ireland
| | - Alice Stanton
- Molecular and Cellular Therapeutics, Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Peter Vollenweider
- Department of Internal Medicine, Centre Hospitalier Universitaire Vaudois and University of Lausanne, Lausanne, Switzerland
| | - Alexander Teumer
- Interfaculty Institute for Genetics and Functional Genomics, University of Greifswald, Greifswald, Germany
| | - Henry Völzke
- Institute for Community Medicine, University of Greifswald, Greifswald, Germany
| | - Rainer Rettig
- Institute of Physiology, University of Greifswald, Greifswald, Germany
| | - Christopher Newton-Cheh
- Center for Human Genetic Research and Cardiovascular Research Center, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
- Program in Medical and Population Genetics, Broad Institute, Cambridge, Massachusetts, United States of America
| | - Pankaj Arora
- Center for Human Genetic Research and Cardiovascular Research Center, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
- Program in Medical and Population Genetics, Broad Institute, Cambridge, Massachusetts, United States of America
| | - Feng Zhang
- Department of Twin Research and Genetic Epidemiology, King's College London, London, United Kingdom
| | - Nicole Soranzo
- Department of Twin Research and Genetic Epidemiology, King's College London, London, United Kingdom
- Wellcome Trust Sanger Institute, Genome Campus, Hinxton, United Kingdom
| | - Timothy D. Spector
- Department of Twin Research and Genetic Epidemiology, King's College London, London, United Kingdom
| | - Gavin Lucas
- Cardiovascular Epidemiology and Genetics Group, Institut Municipal d'Investigacio Medica, Barcelona, Spain
| | - Sekar Kathiresan
- Center for Human Genetic Research and Cardiovascular Research Center, Massachusetts General Hospital, Harvard Medical School, Boston, Massachusetts, United States of America
- Program in Medical and Population Genetics, Broad Institute, Cambridge, Massachusetts, United States of America
| | - David S. Siscovick
- Cardiovascular Health Research Unit, Departments of Medicine and Epidemiology, University of Washington, Seattle, Washington, United States of America
| | - Jian'an Luan
- MRC Epidemiology Unit, Institute of Metabolic Science, Cambridge, United Kingdom
| | - Ruth J. F. Loos
- MRC Epidemiology Unit, Institute of Metabolic Science, Cambridge, United Kingdom
| | - Nicholas J. Wareham
- MRC Epidemiology Unit, Institute of Metabolic Science, Cambridge, United Kingdom
| | - Brenda W. Penninx
- Department of Psychiatry/EMGO Institute, Neuroscience Campus, VU University Medical Center, Amsterdam, The Netherlands
- Department of Psychiatry, Leiden University Medical Center, Leiden, The Netherlands
- Department of Psychiatry, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Ilja M. Nolte
- Unit of Genetic Epidemiology and Bioinformatics, Department of Epidemiology, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands
| | - Martin McBride
- Institute of Cardiovascular and Medical Sciences, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - William H. Miller
- Institute of Cardiovascular and Medical Sciences, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Stuart A. Nicklin
- Institute of Cardiovascular and Medical Sciences, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Andrew H. Baker
- Institute of Cardiovascular and Medical Sciences, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Delyth Graham
- Institute of Cardiovascular and Medical Sciences, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Robert A. McDonald
- Institute of Cardiovascular and Medical Sciences, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Jill P. Pell
- Public Health and Health Policy Section, University of Glasgow, Glasgo, United Kingdom
| | - Naveed Sattar
- Institute of Cardiovascular and Medical Sciences, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | - Paul Welsh
- Institute of Cardiovascular and Medical Sciences, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
| | | | - Patricia Munroe
- Clinical Pharmacology and Barts and the London Genome Centre, William Harvey Research Institute, Barts and the London School of Medicine, Queen Mary University of London, London, United Kingdom
| | - Mark J. Caulfield
- Clinical Pharmacology and Barts and the London Genome Centre, William Harvey Research Institute, Barts and the London School of Medicine, Queen Mary University of London, London, United Kingdom
| | - Alberto Zanchetti
- Istituto Auxologico Italiano, Milan, Italy
- University of Milano, Milano, Italy
| | - Anna F. Dominiczak
- Institute of Cardiovascular and Medical Sciences, College of Medical Veterinary and Life Sciences, University of Glasgow, Glasgow, United Kingdom
- * E-mail:
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Craddock N, Hurles ME, Cardin N, Pearson RD, Plagnol V, Robson S, Vukcevic D, Barnes C, Conrad DF, Giannoulatou E, Holmes C, Marchini JL, Stirrups K, Tobin MD, Wain LV, Yau C, Aerts J, Ahmad T, Andrews TD, Arbury H, Attwood A, Auton A, Ball SG, Balmforth AJ, Barrett JC, Barroso I, Barton A, Bennett AJ, Bhaskar S, Blaszczyk K, Bowes J, Brand OJ, Braund PS, Bredin F, Breen G, Brown MJ, Bruce IN, Bull J, Burren OS, Burton J, Byrnes J, Caesar S, Clee CM, Coffey AJ, Connell JMC, Cooper JD, Dominiczak AF, Downes K, Drummond HE, Dudakia D, Dunham A, Ebbs B, Eccles D, Edkins S, Edwards C, Elliot A, Emery P, Evans DM, Evans G, Eyre S, Farmer A, Ferrier IN, Feuk L, Fitzgerald T, Flynn E, Forbes A, Forty L, Franklyn JA, Freathy RM, Gibbs P, Gilbert P, Gokumen O, Gordon-Smith K, Gray E, Green E, Groves CJ, Grozeva D, Gwilliam R, Hall A, Hammond N, Hardy M, Harrison P, Hassanali N, Hebaishi H, Hines S, Hinks A, Hitman GA, Hocking L, Howard E, Howard P, Howson JMM, Hughes D, Hunt S, Isaacs JD, Jain M, Jewell DP, Johnson T, Jolley JD, Jones IR, Jones LA, Kirov G, Langford CF, Lango-Allen H, Lathrop GM, Lee J, Lee KL, Lees C, Lewis K, Lindgren CM, Maisuria-Armer M, Maller J, Mansfield J, Martin P, Massey DCO, McArdle WL, McGuffin P, McLay KE, Mentzer A, Mimmack ML, Morgan AE, Morris AP, Mowat C, Myers S, Newman W, Nimmo ER, O'Donovan MC, Onipinla A, Onyiah I, Ovington NR, Owen MJ, Palin K, Parnell K, Pernet D, Perry JRB, Phillips A, Pinto D, Prescott NJ, Prokopenko I, Quail MA, Rafelt S, Rayner NW, Redon R, Reid DM, Renwick, Ring SM, Robertson N, Russell E, St Clair D, Sambrook JG, Sanderson JD, Schuilenburg H, Scott CE, Scott R, Seal S, Shaw-Hawkins S, Shields BM, Simmonds MJ, Smyth DJ, Somaskantharajah E, Spanova K, Steer S, Stephens J, Stevens HE, Stone MA, Su Z, Symmons DPM, Thompson JR, Thomson W, Travers ME, Turnbull C, Valsesia A, Walker M, Walker NM, Wallace C, Warren-Perry M, Watkins NA, Webster J, Weedon MN, Wilson AG, Woodburn M, Wordsworth BP, Young AH, Zeggini E, Carter NP, Frayling TM, Lee C, McVean G, Munroe PB, Palotie A, Sawcer SJ, Scherer SW, Strachan DP, Tyler-Smith C, Brown MA, Burton PR, Caulfield MJ, Compston A, Farrall M, Gough SCL, Hall AS, Hattersley AT, Hill AVS, Mathew CG, Pembrey M, Satsangi J, Stratton MR, Worthington J, Deloukas P, Duncanson A, Kwiatkowski DP, McCarthy MI, Ouwehand W, Parkes M, Rahman N, Todd JA, Samani NJ, Donnelly P. Genome-wide association study of CNVs in 16,000 cases of eight common diseases and 3,000 shared controls. Nature 2010; 464:713-20. [PMID: 20360734 PMCID: PMC2892339 DOI: 10.1038/nature08979] [Citation(s) in RCA: 594] [Impact Index Per Article: 42.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2009] [Accepted: 03/05/2010] [Indexed: 01/13/2023]
Abstract
Copy number variants (CNVs) account for a major proportion of human genetic polymorphism and have been predicted to play an important role in genetic susceptibility to common disease. To address this we undertook a large direct genome-wide study of association between CNVs and eight common human diseases. Using a purpose-designed array we typed ~19,000 individuals into distinct copy-number classes at 3,432 polymorphic CNVs, including an estimated ~50% of all common CNVs larger than 500bp. We identified several biological artefacts that lead to false-positive associations, including systematic CNV differences between DNAs derived from blood and cell-lines. Association testing and follow-up replication analyses confirmed three loci where CNVs were associated with disease, IRGM for Crohn's disease, HLA for Crohn's disease, rheumatoid arthritis, and type 1 diabetes, and TSPAN8 for type 2 diabetes, though in each case the locus had previously been identified in SNP-based studies, reflecting our observation that the majority of common CNVs which are well-typed on our array are well tagged by SNPs and so have been indirectly explored through SNP studies. We conclude that common CNVs which can be typed on existing platforms are unlikely to contribute greatly to the genetic basis of common human diseases.
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Dorrian CA, Toole BJ, Alvarez-Madrazo S, Kelly A, Connell JMC, Wallace AM. A screening procedure for primary aldosteronism based on the Diasorin Liaison® automated chemiluminescent immunoassay for direct renin. Ann Clin Biochem 2010; 47:195-9. [DOI: 10.1258/acb.2010.009230] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Background Primary aldosteronism (PA), the most common secondary cause of hypertension, can be screened for using the aldosterone/renin ratio. This ratio is raised in PA and its accuracy depends on the ability to measure plasma renin at extremely low concentrations. Methods We compared two different procedures for assessing plasma renin. The conventional method, which measures plasma renin activity (PRA), is technically demanding and laborious, and the Diasorin Liaison® method, which measures plasma renin concentration (PRC), is an automated immunoassay. Results from each method were used to calculate the aldosterone/renin ratio (ARR) and the performance of the Diasorin Liaison® method compared with that of the conventional assay using receiver operator characteristic curves. Results The analytical and functional sensitivity of the PRC method were 2.1 and 5 μIU/mL, respectively. Intra- and inter-assay precision were <7.2% and 10.4%, respectively. There was significant (9%) prorenin interference. Samples with PRA > 1.0 ng/mL/h showed significant correlation with PRC ( r = 0.93; P < 0.05; n = 146); however, with PRA < 1.0 ng/mL/h, no significant correlation occurred ( r = 0.14; P < 0.05; n = 79). An aldosterone (pmol/L)/PRC(μIU/mL) ratio of >35, in patients with aldosterone >300 pmol/L, resulted in 100% sensitivity and 93% specificity, when compared with the commonly accepted aldosterone (pmol/L)/PRA (ng/mL/h) ratio of >750, in identifying patients who may suffer from PA. Conclusion This study indicates the feasibility of using the automated PRC assay as a replacement for the conventional manual PRA assay in calculating the ARR as a first-line screen for PA.
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Affiliation(s)
- C A Dorrian
- Department of Clinical Biochemistry, Macewen Building, Royal Infirmary, Glasgow G4 0SF
| | - B J Toole
- Department of Clinical Biochemistry, Macewen Building, Royal Infirmary, Glasgow G4 0SF
| | - S Alvarez-Madrazo
- BHF Glasgow Cardiovascular Research Centre, Faculty of Medicine, University of Glasgow, Glasgow G12 8TA, Scotland
| | - A Kelly
- Department of Clinical Biochemistry, Macewen Building, Royal Infirmary, Glasgow G4 0SF
| | - J M C Connell
- BHF Glasgow Cardiovascular Research Centre, Faculty of Medicine, University of Glasgow, Glasgow G12 8TA, Scotland
| | - A M Wallace
- Department of Clinical Biochemistry, Macewen Building, Royal Infirmary, Glasgow G4 0SF
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Freel EM, Tsorlalis IK, Lewsey JD, Latini R, Maggioni AP, Solomon S, Pitt B, Connell JMC, McMurray JJV. Aldosterone status associated with insulin resistance in patients with heart failure--data from the ALOFT study. Heart 2009; 95:1920-4. [PMID: 19713201 DOI: 10.1136/hrt.2009.173344] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
BACKGROUND Aldosterone has a key role in the pathophysiology of heart failure. In around 50% of such patients, aldosterone "escapes" from inhibition by drugs that interrupt the renin-angiotensin axis; such patients have a worse clinical outcome. Insulin resistance is a risk factor in heart failure and cardiovascular disease. The relation between aldosterone status and insulin sensitivity was investigated in a cohort of heart failure patients. METHODS 302 patients with New York Heart Association (NYHA) class II-IV heart failure on conventional therapy were randomised in the ALiskiren Observation of heart Failure Treatment study (ALOFT), designed to test the safety of a directly acting renin inhibitor. Plasma aldosterone and 24-hour urinary aldosterone excretion, as well as fasting insulin and homeostasis model assessment of insulin resistance (HOMA-IR) were measured. Subjects with aldosterone escape and high urinary aldosterone were identified according to previously accepted definitions. RESULTS 20% of subjects demonstrated aldosterone escape and 34% had high urinary aldosterone levels. At baseline, there was a positive correlation between fasting insulin and plasma (r = 0.22 p<0.01) and urinary aldosterone(r = 0.19 p<0.03). Aldosterone escape and high urinary aldosterone subjects both demonstrated higher levels of fasting insulin (p<0.008, p<0.03), HOMA-IR (p<0.06, p<0.03) and insulin-glucose ratios (p<0.006, p<0.06) when compared to low aldosterone counterparts. All associations remained significant when adjusted for potential confounders. CONCLUSIONS This study demonstrates a novel direct relation between aldosterone status and insulin resistance in heart failure. This observation merits further study and may identify an additional mechanism that contributes to the adverse clinical outcome associated with aldosterone escape.
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Affiliation(s)
- E M Freel
- BHF Glasgow Cardiovascular Research Centre, University of Glasgow, Glasgow G12 8TA, UK.
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Davies E, Mackenzie SM, Freel EM, Alvarez-Madrazo S, Fraser R, Connell JMC. Altered corticosteroid biosynthesis in essential hypertension: A digenic phenomenon. Mol Cell Endocrinol 2009; 300:185-91. [PMID: 18848600 DOI: 10.1016/j.mce.2008.09.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/20/2008] [Accepted: 09/10/2008] [Indexed: 10/21/2022]
Abstract
Aldosterone plays an important role in electrolyte and blood pressure homeostasis. Our studies have focused on the role of aldosterone in essential hypertension. We have shown that plasma aldosterone and ARR are heritable characteristics and that aldosterone concentrations in older subjects are inversely correlated with birthweight and positively correlated with blood pressure. Aldosterone levels are also associated with polymorphic variation in the CYP11B2 gene, which encodes aldosterone synthase, the enzyme responsible for aldosterone production. Interestingly, CYP11B2 polymorphisms are also associated with less efficient activity of 11beta-hydroxylase, encoded by the neighbouring, highly homologous CYP11B1 gene. We propose that a digenic effect leads to increased aldosterone production, with inefficient 11beta-hydroxylation causing a long-term increase in ACTH drive to the adrenal gland and enhanced expression of CYP11B2, thereby resulting in chronically raised aldosterone secretion in response to factors such as angiotensin II and potassium. In susceptible subjects this is likely, over many years, to result in hypertension with relative aldosterone excess.
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Affiliation(s)
- Eleanor Davies
- MRC Blood Pressure Group, BHF Glasgow Cardiovascular Research Centre, University of Glasgow, 126 University Place, Glasgow G12 8TA, United Kingdom.
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Holloway CD, MacKenzie SM, Fraser R, Miller S, Barr M, Wilkinson D, Forbes GH, Friel E, Connell JMC, Davies E. Effects of genetic variation in the aldosterone synthase (CYP11B2) gene on enzyme function. Clin Endocrinol (Oxf) 2009; 70:363-71. [PMID: 18710464 DOI: 10.1111/j.1365-2265.2008.03383.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
OBJECTIVE Evidence suggests that high levels of aldosterone lead to hypertension and increased risk of cardiovascular disease. Around 15% of patients with essential hypertension have a raised aldosterone to renin ratio (ARR) suggesting that aldosterone production is inappropriately high in relation to its principal agonist angiotensin II. This may be due to increased activity of aldosterone synthase caused by genetic variation in the CYP11B2 gene. We screened the coding region of human CYP11B2 for genetic variants and tested their effects on function in vitro. PROTOCOL Normotensive subjects (n = 69) were screened for sequence variants in the coding region of CYP11B2 by single-stranded conformation polymorphism (SSCP) analysis and sequencing. The effects of nonsynonymous variants on enzyme activity were assessed in JEG-3 cells transiently transfected with wild-type or variant expression plasmids. The conversion of the substrate 11-deoxycorticosterone (DOC) to corticosterone (B) and aldosterone was measured. RESULTS Twenty variants were detected in CYP11B2 and eight analysed functionally (Arg87Gly, Asn281Thr, Gly288Ser, Lys296Asn, Asp335Asn, Gln404Arg, Ala414Pro and His439Tyr). Corticosterone synthesis was unaltered and aldosterone synthesis reduced in variant Arg87Gly; Asn281Thr increased corticosterone and decreased aldosterone production; Gly288Ser increased corticosterone production and abolished aldosterone production; Lys296Asn reduced both corticosterone and aldosterone production; Asp335Asn increased corticosterone synthesis but did not affect aldosterone production. Variants Gln404Arg, Ala414Pro and His439Tyr showed increases in both corticosterone and aldosterone synthesis compared to the wild-type. CONCLUSION The study confirms the genetic variability of the CYP11B2 gene and provides us with additional valuable structure-function information.
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Affiliation(s)
- C D Holloway
- MRC Blood Pressure Group, BHF Cardiovascular Research Centre, 126 University Place, University of Glasgow, G12 8TA, UK
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Abstract
CONTEXT Sex steroids (androgens and oestrogens) and corticosteroids (glucocorticoids and mineralocorticoids) have a major impact on fat distribution. Several genes involved in steroid synthesis and metabolism, such as 11beta-hydroxysteroid dehydrogenase type 1 and aromatase, are known to be expressed within adipose tissue, thus modulating local steroid levels; however, our knowledge of which genes are expressed and at what level is incomplete. OBJECTIVE To detect by real-time quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) which of 13 key steroidogenic genes are transcribed within human adipose tissue and to assess whether mRNA levels differ significantly between the subcutaneous abdominal and omental adipose depots. PATIENTS Eight women undergoing caesarean section [age 29.1 +/- 6.5 years, body mass index (BMI) 28.9 +/- 8.4 kg/m(2)]. RESULTS Genes transcribed in both depots were StAR (steroidogenic acute regulatory protein), CYP11A1 (side-chain cleavage enzyme), HSD3B2 (3beta-hydroxysteroid dehydrogenase type 2), CYP21B (21-hydroxylase), CYP19 (aromatase), HSD11B1 (11beta-hydroxysteroid dehydrogenase type 1), HSD17B3, HSD17B5, HSD17B7 (17beta-hydroxysteroid dehydrogenase types 3, 5 and 7) and SRD5A2 (5alpha-reductase type 2). All but SRD5A2 varied significantly in abundance between depots. CYP17 (17alpha-hydroxylase), CYP11B1 (11beta-hydroxylase) and CYP11B2 (aldosterone synthase) transcription were not detected. CONCLUSIONS This study confirms and significantly extends our knowledge of steroidogenic gene expression within adipose tissue, showing that transcript levels are depot specific. We have demonstrated that de novo synthesis from cholesterol of sex steroids, cortisol and aldosterone is not possible because of the absence of key steroidogenic mRNAs. Instead, the pattern of transcription suggests that 11-deoxycorticosterone, a mineralocorticoid, would be the ultimate product of any de novo adipose synthesis.
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Affiliation(s)
- Scott M MacKenzie
- BHF Glasgow Cardiovascular Research Centre, University of Glasgow, Glasgow, United Kingdom.
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Lavery GG, Walker EA, Tiganescu A, Ride JP, Shackleton CHL, Tomlinson JW, Connell JMC, Ray DW, Biason-Lauber A, Malunowicz EM, Arlt W, Stewart PM. Steroid biomarkers and genetic studies reveal inactivating mutations in hexose-6-phosphate dehydrogenase in patients with cortisone reductase deficiency. J Clin Endocrinol Metab 2008; 93:3827-32. [PMID: 18628520 PMCID: PMC2579651 DOI: 10.1210/jc.2008-0743] [Citation(s) in RCA: 70] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CONTEXT Cortisone reductase deficiency (CRD) is characterized by a failure to regenerate cortisol from cortisone via 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1), resulting in increased cortisol clearance, activation of the hypothalamic-pituitary-axis (HPA) and ACTH-mediated adrenal androgen excess. 11beta-HSD1 oxoreductase activity requires the reduced nicotinamide adenine dinucleotide phosphate-generating enzyme hexose-6-phosphate dehydrogenase (H6PDH) within the endoplasmic reticulum. CRD manifests with hyperandrogenism resulting in hirsutism, oligo-amenorrhea, and infertility in females and premature pseudopuberty in males. Recent association studies have failed to corroborate findings that polymorphisms in the genes encoding H6PDH (R453Q) and 11beta-HSD1 (Intron 3 inserted adenine) interact to cause CRD. OBJECTIVE Our objective was to reevaluate the genetics and steroid biochemistry of patients with CRD. DESIGN We analyzed 24-h urine collection for steroid biomarkers by gas chromatography/mass spectrometry and sequenced the HSD11B1 and H6PD genes in our CRD cohort. PATIENTS Patients included four cases presenting with hyperandrogenism and biochemical features clearly indicative of CRD. RESULTS Gas chromatography/mass spectrometry identified steroid biomarkers that correlated with CRD in each case. Three cases were identified as homozygous (R109AfsX3, Y316X, and G359D) and one case identified as compound heterozygous (c.960G-->A and D620fsX3) for mutations in H6PD. No mutations affecting enzyme activity were identified in the HSD11B1 gene. Expression and activity assays demonstrate loss of function for all reported H6PDH mutations. CONCLUSIONS CRD is caused by inactivating mutations in the H6PD gene, rendering the 11beta-HSD1 enzyme unable to operate as an oxoreductase, preventing local glucocorticoid regeneration. These data highlight the importance of the redox control of cortisol metabolism and the 11beta-HSD1-H6PDH pathway in regulating hypothalamic-pituitary-adrenal axis activity.
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Affiliation(s)
- Gareth G Lavery
- Division of Medical Sciences, University of Birmingham, Birmingham B15 2TT, United Kingdom
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Freel EM, Ingram M, Wallace AM, White A, Fraser R, Davies E, Connell JMC. Effect of variation in CYP11B1 and CYP11B2 on corticosteroid phenotype and hypothalamic-pituitary-adrenal axis activity in hypertensive and normotensive subjects. Clin Endocrinol (Oxf) 2008; 68:700-6. [PMID: 17980006 DOI: 10.1111/j.1365-2265.2007.03116.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
BACKGROUND Aldosterone is important in the development of hypertension. We have shown that a single nucleotide polymorphism (SNP) (-344T) in the 5' regulatory region (UTR) of the gene encoding aldosterone synthase (CYP11B2) associates with aldosterone excess and hypertension as well as altered adrenal 11-hydroxylation efficiency (deoxycortisol to cortisol). This conversion is carried out by the enzyme 11beta-hydroxylase, encoded by the adjacent gene, CYP11B1. We proposed that the effects of CYP11B2 are explained by linkage disequilibrium (LD) across the CYP11B locus. We have demonstrated high LD across this locus and identified two SNPs in the 5' UTR of CYP11B1 (-1859 G/T, -1889 A/G) that associate with reduced transcription in vitro and altered 11-hydroxylation efficiency in vivo. Accordingly, we hypothesized that the reduced adrenal 11-hydroxylation may lead to chronic resetting of the pituitary-adrenal axis, with chronically increased ACTH drive resulting in aldosterone excess. METHODS To test this, we examined hypothalamic-pituitary-adrenal (HPA) axis activity in hypertensive and normotensive individuals stratified according to genotype at CYP11B2 (-344T/C) and CYP11B1 (-1859 G/T, -1889 A/G). Fifty-six subjects homozygous for CYP11B2 SNP (27 TT, 12 CC), and 38 homozygous for CYP11B1 SNPs (18 TTGG, 20 GGAA) were recruited. Diurnal variation and the effects of dexamethasone suppression and ACTH stimulation on plasma aldosterone, cortisol and ACTH under controlled conditions were studied. RESULTS Subjects with SNPs associated with reduced 11-hydroxylation efficiency (-344T CYP11B2; TTGG CYP11B1) showed reduced inhibition of ACTH after dexamethasone (P = 0.05) and an altered cortisol-ACTH relationship (decreased cortisol-ACTH ratio, P < 0.02). The same individuals also demonstrated close correlations between plasma cortisol and aldosterone (-344T CYP11B2 r = 0.508, P < 0.004; TTGG CYP11B1 r = 0.563, P < 0.003) suggesting that there was common regulation (possibly ACTH) of these hormones in genetically susceptible subjects. CONCLUSIONS Variation in CYP11B2 and CYP11B1 associates with chronic up-regulation of the HPA axis. These novel data support the suggestion that chronic aldosterone excess, in genetically susceptible individuals, may be a consequence of increased ACTH drive to the adrenal and identify novel molecular mechanisms that may lead to the development of hypertension within the general population.
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Affiliation(s)
- E M Freel
- Glasgow Cardiovascular Research Centre, University of Glasgow, Glasgow, G12 8TA, UK.
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Connell JMC, MacKenzie SM, Freel EM, Fraser R, Davies E. A lifetime of aldosterone excess: long-term consequences of altered regulation of aldosterone production for cardiovascular function. Endocr Rev 2008; 29:133-54. [PMID: 18292466 DOI: 10.1210/er.2007-0030] [Citation(s) in RCA: 132] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Up to 15% of patients with essential hypertension have inappropriate regulation of aldosterone; although only a minority have distinct adrenal tumors, recent evidence shows that mineralocorticoid receptor activation contributes to the age-related blood pressure rise and illustrates the importance of aldosterone in determining cardiovascular risk. Aldosterone also has a major role in progression and outcome of ischemic heart disease. These data highlight the need to understand better the regulation of aldosterone synthesis and its action. Aldosterone effects are mediated mainly through classical nuclear receptors that alter gene transcription. In classic epithelial target tissues, signaling mechanisms are relatively well defined. However, aldosterone has major effects in nonepithelial tissues that include increased synthesis of proinflammatory molecules and reactive oxygen species; it remains unclear how these effects are controlled and how receptor specificity is maintained. Variation in aldosterone production reflects interaction of genetic and environmental factors. Although the environmental factors are well understood, the genetic control of aldosterone synthesis is still the subject of debate. Aldosterone synthase (encoded by the CYP11B2 gene) controls conversion of deoxycorticosterone to aldosterone. Polymorphic variation in CYP11B2 is associated with increased risk of hypertension, but the molecular mechanism that accounts for this is not known. Altered 11beta-hydroxylase efficiency (conversion of deoxycortisol to cortisol) as a consequence of variation in the neighboring gene (CYP11B1) may be important in contributing to altered control of aldosterone synthesis, so that the risk of hypertension may reflect a digenic effect, a concept that is discussed further. There is evidence that a long-term increase in aldosterone production from early life is determined by an interaction of genetic and environmental factors, leading to the eventual phenotypes of aldosterone-associated hypertension and cardiovascular damage in middle age and beyond. The importance of aldosterone has generated interest in its therapeutic modulation. Disadvantages associated with spironolactone (altered libido, gynecomastia) have led to a search for alternative mineralocorticoid receptor antagonists. Of these, eplerenone has been shown to reduce cardiovascular risk after myocardial infarction. The benefits and disadvantages of this therapeutic approach are discussed.
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Affiliation(s)
- John M C Connell
- Division of Cardiovascular and Medical Sciences, British Heart Foundation Glasgow Cardiovascular Research Centre, 126 University Place, Glasgow, United Kingdom.
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20
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Boyle JG, Logan PJ, Ewart MA, Reihill JA, Ritchie SA, Connell JMC, Cleland SJ, Salt IP. Rosiglitazone stimulates nitric oxide synthesis in human aortic endothelial cells via AMP-activated protein kinase. J Biol Chem 2008; 283:11210-7. [PMID: 18303014 DOI: 10.1074/jbc.m710048200] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The thiazolidinedione anti-diabetic drugs increase activation of endothelial nitric-oxide (NO) synthase by phosphorylation at Ser-1177 and increase NO bioavailability, yet the molecular mechanisms that underlie this remain poorly characterized. Several protein kinases, including AMP-activated protein kinase, have been demonstrated to phosphorylate endothelial NO synthase at Ser-1177. In the current study we determined the role of AMP-activated protein kinase in rosiglitazone-stimulated NO synthesis. Stimulation of human aortic endothelial cells with rosiglitazone resulted in the time- and dose-dependent stimulation of AMP-activated protein kinase activity and NO production with concomitant phosphorylation of endothelial NO synthase at Ser-1177. Rosiglitazone stimulated an increase in the ADP/ATP ratio in endothelial cells, and LKB1 was essential for rosiglitazone-stimulated AMPK activity in HeLa cells. Infection of endothelial cells with a virus encoding a dominant negative AMP-activated protein kinase mutant abrogated rosiglitazone-stimulated Ser-1177 phosphorylation and NO production. Furthermore, the stimulation of AMP-activated protein kinase and NO synthesis by rosiglitazone was unaffected by the peroxisome proliferator-activated receptor-gamma inhibitor GW9662. These studies demonstrate that rosiglitazone is able to acutely stimulate NO synthesis in cultured endothelial cells by an AMP-activated protein kinase-dependent mechanism, likely to be mediated by LKB1.
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Affiliation(s)
- James G Boyle
- The Henry Wellcome Laboratory for Cell Biology, Division of Biochemistry and Molecular Biology, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow, UK
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21
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Ye P, Kenyon CJ, MacKenzie SM, Nichol K, Seckl JR, Fraser R, Connell JMC, Davies E. Effects of ACTH, dexamethasone, and adrenalectomy on 11beta-hydroxylase (CYP11B1) and aldosterone synthase (CYP11B2) gene expression in the rat central nervous system. J Endocrinol 2008; 196:305-11. [PMID: 18252953 PMCID: PMC2229629 DOI: 10.1677/joe-07-0439] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
Using a highly sensitive quantitative RT-PCR method for the measurement of CYP11B1 (11beta-hydroxylase) and CYP11B2 (aldosterone synthase) mRNAs, we previously demonstrated that CYP11B2 expression in the central nervous system (CNS) is subject to regulation by dietary sodium. We have now quantified the expression of these genes in the CNS of male Wistar Kyoto (WKY) rats in response to systemic ACTH infusion, dexamethasone infusion, and to adrenalectomy. CYP11B1 and CYP11B2 mRNA levels were measured in total RNA isolated from the adrenal gland and discrete brain regions using real-time quantitative RT-PCR. ACTH infusion (40 ng/day for 7 days, N=8) significantly increased CYP11B1 mRNA in the adrenal gland, hypothalamus, and cerebral cortex compared with animals infused with vehicle only. ACTH infusion decreased adrenal CYP11B2 expression but increased expression in all of the CNS regions except the cortex. Dexamethasone (10 microg/day for 7 days, N=8) reduced adrenal CYP11B1 mRNA compared with control animals but had no significant effect on either gene's expression in the CNS. Adrenalectomy (N=6 per group) significantly increased CYP11B1 expression in the hippocampus and hypothalamus and raised CYP11B2 expression in the cerebellum relative to sham-operated animals. This study confirms the transcription of CYP11B1 and CYP11B2 throughout the CNS and demonstrates that gene transcription is subject to differential regulation by ACTH and circulating corticosteroid levels.
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Affiliation(s)
- Ping Ye
- MRC Blood Pressure Group, Division of Cardiovascular and Medical Sciences, BHF Glasgow Cardiovascular Research Centre126 University Place, Glasgow G12 8TAUK
| | - Christopher J Kenyon
- The Queen's Medical Research Institute, Centre for Cardiovascular Science47 Little France Crescent, Edinburgh EH16 4TJUK
| | - Scott M MacKenzie
- MRC Blood Pressure Group, Division of Cardiovascular and Medical Sciences, BHF Glasgow Cardiovascular Research Centre126 University Place, Glasgow G12 8TAUK
| | - Katherine Nichol
- The Queen's Medical Research Institute, Centre for Cardiovascular Science47 Little France Crescent, Edinburgh EH16 4TJUK
| | - Jonathan R Seckl
- The Queen's Medical Research Institute, Centre for Cardiovascular Science47 Little France Crescent, Edinburgh EH16 4TJUK
| | - Robert Fraser
- MRC Blood Pressure Group, Division of Cardiovascular and Medical Sciences, BHF Glasgow Cardiovascular Research Centre126 University Place, Glasgow G12 8TAUK
| | - John M C Connell
- MRC Blood Pressure Group, Division of Cardiovascular and Medical Sciences, BHF Glasgow Cardiovascular Research Centre126 University Place, Glasgow G12 8TAUK
| | - Eleanor Davies
- MRC Blood Pressure Group, Division of Cardiovascular and Medical Sciences, BHF Glasgow Cardiovascular Research Centre126 University Place, Glasgow G12 8TAUK
- (Correspondence should be addressed to E Davies; )
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McManus F, McInnes GT, Connell JMC. Drug Insight: eplerenone, a mineralocorticoid-receptor antagonist. ACTA ACUST UNITED AC 2008; 4:44-52. [PMID: 18084345 DOI: 10.1038/ncpendmet0676] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2007] [Accepted: 10/03/2007] [Indexed: 01/21/2023]
Abstract
Increasing recognition of the role of aldosterone in cardiovascular disease has been supported by a significant body of evidence from animal models. This evidence has been translated into clinical practice, and large-scale, randomized, placebo-controlled trials have confirmed the beneficial effects of mineralocorticoid blockade in patients with heart failure. As a consequence, there has been a resurgence in the use of mineralocorticoid-receptor antagonists in clinical practice that has prompted the search for a potent and specific antagonist without the sexual side effects of spironolactone. Eplerenone, a mineralocorticoid-receptor antagonist with minimal binding to the progesterone and androgen receptors, is now licensed for treatment of heart failure in Europe and heart failure and hypertension in the US; it has also been proposed as a treatment for a variety of cardiovascular conditions. This article reviews the current concepts of the actions of aldosterone at a cellular level. Recent findings regarding its role as a cardiovascular hormone, both in animal models and human studies, are discussed. We also describe the development of mineralocorticoid-receptor blockers following the isolation of aldosterone and discuss the subsequent search for a specific mineralocorticoid antagonist. In addition we detail the effects of eplerenone in a number of clinical situations and outline its potential future applications.
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MacKenzie SM, Dewar D, Stewart W, Fraser R, Connell JMC, Davies E. The transcription of steroidogenic genes in the human cerebellum and hippocampus: a comparative survey of normal and Alzheimer's tissue. J Endocrinol 2008; 196:123-30. [PMID: 18180323 DOI: 10.1677/joe-07-0427] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Steroid actions on brain tissue have been implicated in processes such as blood pressure regulation and neurodegeneration, including the progression of Alzheimer's disease (AD). mRNAs from all of the genes required for de novo synthesis from cholesterol of aldosterone and corticosterone (equivalent to cortisol in humans) have been identified in rat brain, together with abundant steroid hormone receptors, but the situation in human brain requires clarification. We used real-time RT-PCR to assess whether transcription of 13 steroid-associated genes occurs in human hippocampus and cerebellum, and to identify whether transcription of these genes is significantly altered in cases of AD. Frozen post-mortem samples of hippocampus and cerebellum from patients with AD (n=7) and age-matched controls free from neurological disease at the time of death (n=9) were used. We found all of the genes under investigation to be transcribed within normal and AD hippocampus and cerebellum except for CYP11B1 (11beta-hydroxylase), CYP11B2 (aldosterone synthase) and CYP17 (17alpha-hydroxylase). No significant differences in mRNA levels were observed between the AD tissue and the equivalent control tissue, although significant regional differences in gene transcription were observed between hippocampus and cerebellum in AD and control samples. The absence of key mRNAs from human hippocampus and cerebellum rules out the de novo generation of aldosterone, cortisol or the sex steroids within these regions. However, the pattern of gene expression does suggest that the mineralocorticoid 11-deoxycorticosterone can be generated de novo. There is no evidence of a link between AD and altered steroid biosynthesis within human hippocampus and cerebellum.
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Affiliation(s)
- Scott M MacKenzie
- BHF Glasgow Cardiovascular Research Centre, University of Glasgow, 126 University Place, Glasgow G12 8TA, UK
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24
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Boyle JG, Davidson DF, Perry CG, Connell JMC. Comparison of diagnostic accuracy of urinary free metanephrines, vanillyl mandelic Acid, and catecholamines and plasma catecholamines for diagnosis of pheochromocytoma. J Clin Endocrinol Metab 2007; 92:4602-8. [PMID: 17635948 DOI: 10.1210/jc.2005-2668] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
CONTEXT Recent evidence suggests that plasma-free metanephrines provide a highly sensitive test in patients requiring exclusion of pheochromocytoma. The diagnostic efficacy of urinary free metanephrines, however, has not been evaluated. OBJECTIVE, DESIGN, SETTING, PATIENTS, AND OUTCOME MEASURES: We compared retrospectively the diagnostic efficacy of 24-h urinary free metanephrines with our currently available measurements of 24-h urinary vanillyl mandelic acid (VMA), urinary catecholamines, and plasma catecholamines in 159 outpatients tested in a tertiary referral center for pheochromocytoma over a 4-yr period. RESULTS The sensitivity of urinary free metanephrines was 100% [25 of 25 patients; 95% confidence interval (CI) 86-100%)] compared with the sensitivity of 84% (21 of 25; 95% CI 64-95%) for urinary catecholamines; 72% (18 of 25; 95% CI 51-88%) for urinary VMA; and 76% (16 of 21; 95% CI 53-92%) for plasma catecholamines. The specificity of urinary free metanephrines was 94% (116 of 123; 95% CI 89-98%), compared with the specificity of 99% (127 of 129; 95% CI 96-100%) for urinary catecholamines; 96% (130 of 134; 95% CI 91-98%) for urinary VMA; and 88% (66 of 75; 95% CI 78-94%) for plasma catecholamines. Receiver operating characteristic curves for all test groups were generated. Pairwise comparisons of the area under the receiver operating characteristic curve for urinary free metanephrines with that of each of the other three test groups individually were: 0.993 (95% CI 0.962-0.999) vs. 0.919 (95% CI 0.862-0.957, P = 0.032) for urine catecholamines; 0.993 (95% CI 0.962-0.999) vs. 0.846 (95% CI 0.778-0.900, P = 0.002) for urine VMA; and 0.992 (95% CI 0.945-0.998) vs. 0.852 (95% CI 0.762-0.918, P = 0.009) for plasma catecholamines. Testing with urinary free metanephrines failed to misidentify a single case of pheochromocytoma, compared with four missed cases for urinary catecholamines, seven missed cases for urinary VMA, and five missed cases for plasma catecholamines. CONCLUSION Urinary free metanephrines were superior to urinary VMA, urinary catecholamines, and plasma catecholamines and can provide a valuable test for diagnosis of pheochromocytoma in adults.
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Affiliation(s)
- James G Boyle
- Division of Cardiovascular and Medical Sciences, Western Infirmary, University of Glasgow, Glasgow G12 8TA, United Kingdom
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25
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Freel EM, Ingram M, Friel EC, Fraser R, Brown M, Samani NJ, Caulfield M, Munroe P, Farrall M, Webster J, Clayton D, Dominiczak AF, Davies E, Connell JMC. Phenotypic consequences of variation across the aldosterone synthase and 11-beta hydroxylase locus in a hypertensive cohort: data from the MRC BRIGHT Study. Clin Endocrinol (Oxf) 2007; 67:832-8. [PMID: 17651452 DOI: 10.1111/j.1365-2265.2007.02971.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND Aldosterone is an important cardiovascular hormone; 15% of hypertensive subjects have alteration in aldosterone regulation, defined by a raised ratio of aldosterone to renin (ARR). Studies of the aldosterone synthase gene (CYP11B2) have focused on a single nucleotide polymorphism in the 5'promoter region (-344 C/T). In normotensive subjects, the T allele associates with raised levels of the 11-deoxysteroids, deoxycorticosterone and 11-deoxycortisol which are substrates for 11beta-hydroxylase, encoded by the adjacent and homologous gene, CYP11B1. We have speculated that this altered 11beta-hydroxylase efficiency leads to increased ACTH drive to the adrenal gland to maintain cortisol production and reported herein the association between the -344 C/T single nucleotide polymorphism (SNP) and adrenal steroid production in subjects with essential hypertension. METHODS The CYP11B2-344 C/T polymorphism was genotyped and urinary excretion of adrenal steroid metabolites was measured (by GCMS) in 511 unrelated hypertensives from the Medical Research Council (MRC) British Genetics of Hypertension (BRIGHT) study. RESULTS Thirty-five per cent of subjects were homozygous for the -344T allele whilst 16% were CC homozygotes. There was no difference in cortisol excretion rate between the two genotype groups but the index of adrenal 11beta-hydroxylation (ratio of tetrahydrodeoxycortisol/total cortisol) was significantly higher in the TT group (P < 0.005) than in the CC group. Excretion rates of the major urinary metabolite of aldosterone (tetrahydroaldosterone) correlated strongly with the ACTH-regulated steroids, cortisol (r = 0.437, P < 0.0001) and total androgen metabolites (r = 0.4, P < 0.0001) in TT but not CC subjects. CONCLUSIONS Hypertensives homozygous for the -344 T allele of CYP11B2 demonstrate altered 11beta-hydroxylase efficiency (CYP11B1); this is consistent with the hypothesis of a genetically determined increase in adrenal ACTH drive in these subjects. The correlation between excretion of aldosterone and cortisol metabolites and suggests that, in TT subjects, ACTH exerts an important common regulatory influence on adrenal corticosteroid production in subjects with hypertension.
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Affiliation(s)
- E M Freel
- Glasgow Cardiovascular Research Centre, University of Glasgow, 126 University Place, Glasgow, UK.
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26
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Baker M, Rahman T, Hall D, Avery PJ, Mayosi BM, Connell JMC, Farrall M, Watkins H, Keavney B. The C-532T polymorphism of the angiotensinogen gene is associated with pulse pressure: a possible explanation for heterogeneity in genetic association studies of AGT and hypertension. Int J Epidemiol 2007; 36:1356-62. [PMID: 17998241 DOI: 10.1093/ije/dym213] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND Many previous studies have investigated whether there is an association between genotypes at the angiotensinogen (AGT) gene and hypertensive status, but few have incorporated quantitative data. Although meta-analyses support a possible effect of AGT variants on blood pressure (BP), substantial unexplained between-study heterogeneity has been observed. We hypothesized that a primary effect of AGT variants on arterial stiffness (and thus pulse pressure) might explain such heterogeneity, and tested for such an effect in a family study. METHODS We studied 1425 individuals from 248 families ascertained through a proband with essential hypertension. BP was measured using 24 h ambulatory monitoring, and polymorphisms of the AGT gene that had been previously associated with hypertension and/or plasma angiotensinogen levels were typed. Pulse pressure was used as a measurement of arterial stiffness. RESULTS We observed a highly significant association between genotypes at the AGT C-532T polymorphism and pulse pressure (p = 0.00006). Each T allele was associated with a 5% lower pulse pressure (that is, an additive effect). This resulted from opposing genotypic effects to (slightly) lower systolic BP and (slightly) elevate DBP. CONCLUSIONS These results suggest that genetic variation at the angiotensinogen locus may primarily affect arterial stiffness, and therefore pulse pressure. The heterogeneity between previous genetic studies of AGT and hypertension status could in part be explained by this finding, since case selection criteria based on systolic BP, diastolic BP, or both would result in different levels of selection for the -532T allele.
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Affiliation(s)
- Michelle Baker
- The Institute of Human Genetics, Newcastle University, UK
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Thomson AH, Devers MC, Wallace AM, Grant D, Campbell K, Freel M, Connell JMC. Variability in hydrocortisone plasma and saliva pharmacokinetics following intravenous and oral administration to patients with adrenal insufficiency. Clin Endocrinol (Oxf) 2007; 66:789-96. [PMID: 17437510 DOI: 10.1111/j.1365-2265.2007.02812.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVE The best method for determining hydrocortisone replacement therapy is not well defined. This study aimed to assess interindividual variability in cortisol pharmacokinetics and to investigate whether measurement of salivary cortisol provides a useful alternative to plasma concentration measurements. DESIGN Intravenous (IV) and oral crossover. PATIENTS Twenty-seven patients with primary or secondary adrenal insufficiency who had been on stable replacement therapy for at least 3 months. MEASUREMENTS Plasma and salivary concentrations of cortisol were measured up to 8 h following administration of hydrocortisone. RESULTS After IV administration, Cmax ranged from 715 to 8313 nmol/l, area under the curve (AUC) from 1112 to 12 177 nmol h/l and cortisol clearance had a median (range) of 0.267 (0.076-0.540) l/h/kg. After oral administration, Cmax ranged from 422 to 1554 nmol/l, AUC 1081-5471 nmol h/l and oral clearance had a median (range) of 0.267 (0.081-0.363) l/h/kg. There was no clear relationship between paired saliva and plasma cortisol concentrations after IV or oral dosing. Plasma and salivary AUC(2-8 h) after IV administration were highly correlated (r2 = 0.77) but differences between predicted and measured plasma AUCs ranged from 3% to 90%. There was a poor correlation between plasma and saliva AUC(2-6 h) after oral administration (r2 = 0.16). CONCLUSIONS The wide interindividual variability in plasma and salivary profiles of cortisol following the administration of IV and oral hydrocortisone to patients with adrenal insufficiency and the poor correlation between salivary and plasma measurements suggest that salivary cortisol measurements cannot be used for individual hydrocortisone dosage adjustment.
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Affiliation(s)
- A H Thomson
- Pharmacy Department, Western Infirmary, Glasgow, UK
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Sainsbury CAR, Coleman J, Brady AJ, Connell JMC, Hillier C, Petrie JR. Endothelium-dependent relaxation is resistant to inhibition of nitric oxide synthesis, but sensitive to blockade of calcium-activated potassium channels in essential hypertension. J Hum Hypertens 2007; 21:808-14. [PMID: 17508013 DOI: 10.1038/sj.jhh.1002226] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
In human essential hypertension (EH), endothelium-dependent relaxation can occur independent of nitric oxide (NO) and prostacyclin (PGI(2)). Recent in vivo data suggest that rapid compensatory upregulation of endothelial cytochrome P450 epoxygenase 2C9 occurs to preserve vasorelaxation under conditions of decreased NO bioavailability. As one of the vascular actions of CYP2C9 is to modulate small and intermediate conductance endothelial calcium-activated potassium channels (SK(Ca) and IK(Ca)), we examined whether endothelium-dependent relaxation is sensitive to inhibitors of these channels (apamin and charybdotoxin) in resistance-sized vessels from human with EH. Subcutaneous gluteal biopsies were performed on 12 humans with EH and 12 matched control subjects. Resistance arteries were dissected and relaxation responses to carbachol were assessed ex vivo using wire myography in the presence of: (i) N(G)-nitro-L-arginine (L-NOARG)/indomethacin; and (ii) apamin/charybdotoxin. Maximal carbachol relaxation was impaired in EH vs control subjects. No differences in responses were observed with the endothelium-independent agonist, S-nitroso-N-acetyl-penicillamine. Relaxation to carbachol was attenuated following incubation with L-NOARG/indomethacin in vessels from control subjects (P<0.01 analysis of variance (ANOVA)), but not in vessels from patients with EH. The reverse pattern was seen following apamin/charybdotoxin with carbachol relaxation attenuated only in EH vessels (P<0.001 ANOVA). Endothelium-dependent relaxation is resistant to endothelial nitric oxide synthase inhibition but sensitive to blockade of calcium-activated potassium channels in human EH. Studies with more specific inhibitors are required to determine whether this response is mediated by endothelial potassium channel subtypes (SK(Ca) and IK(Ca)).
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Ritchie SA, Connell JMC. The link between abdominal obesity, metabolic syndrome and cardiovascular disease. Nutr Metab Cardiovasc Dis 2007; 17:319-326. [PMID: 17110092 DOI: 10.1016/j.numecd.2006.07.005] [Citation(s) in RCA: 430] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2006] [Revised: 07/12/2006] [Accepted: 07/13/2006] [Indexed: 02/06/2023]
Abstract
AIM The prevalence of metabolic syndrome has increased dramatically in recent years, and the cluster of metabolic abnormalities it encompasses results in increased cardiovascular morbidity and mortality. The role of abdominal (visceral) obesity and the underlying molecular and cellular mechanisms central to this association have been the subject of intensive research in recent times. The aim of this review is to correlate data in this area, highlighting the central role of excess visceral fat and its secreted adipokines, and to review existing and emerging therapies. DATA SYNTHESIS Data were generated from a search of the PubMed database using the terms 'abdominal obesity', 'metabolic syndrome', 'insulin resistance', 'adipokines', 'interleukin-6 (IL-6)', 'adiponectin', 'tumour necrosis factor-alpha (TNF-alpha)' and 'cardiovascular disease'. CONCLUSION Metabolic syndrome is associated with a pro-inflammatory state, and the role of visceral obesity is thought to be central to this. Visceral obesity leads to alteration of the normal physiological balance of adipokines, insulin resistance, endothelial dysfunction and a pro-atherogenic state. In association with this, the presence of conventional cardiovascular risk factors such as hypertension, dyslipidaemia and smoking results in a significantly elevated cardiovascular and metabolic (cardiometabolic) risk. Better understanding of the molecular mechanisms central to this association has led to the development of potential therapeutic agents.
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Affiliation(s)
- S A Ritchie
- BHF Cardiovascular Research Centre, Glasgow University, 26 University Place, Glasgow G12 8TA, UK.
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Freel EM, Bernhardt R, Bernhardt M, Ingram M, Ingram R, Wallace AM, Fraser R, Davies E, Connell JMC. Endogenous corticosteroid biosynthesis in subjects after bilateral adrenalectomy. Clin Endocrinol (Oxf) 2007; 66:659-65. [PMID: 17381495 DOI: 10.1111/j.1365-2265.2007.02791.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVE Corticosteroids can be synthesized in extra-adrenal tissues but the contribution of this to circulating levels in humans is not known. Previous in vitro studies suggest that the 'hybrid' corticosteroid 18-oxocortisol (18-oxoF) is produced from cortisol by aldosterone synthase. We looked for evidence of extra-adrenal production of this and other corticosteroids in 10 subjects stable on long-term glucocorticoid replacement following bilateral adrenalectomy. METHODS In phase 1, patients were maintained on cortisol alone (30 mg/day), in phase 2 dexamethasone (2 mg/day), and in phase 3, both cortisol and dexamethasone. Each phase lasted 3 days. MEASUREMENTS On the last day of each phase, 24-h urine collection was performed for analysis of steroid metabolite excretion [using gas chromatography-mass spectrometry (GCMS)] and plasma aldosterone and renin were measured (by radioimmunoassay). RESULTS Cortisol metabolite excretion rate [tetrahydrocortisone (THE) + tetrahydrocortisol (THF) + allotetrahydrocortisol (aTHF)] fell from 9169 nmol/24 h in phase 1 to 22 nmol/24 h in phase 2, rising to 6843 nmol/24 h in phase 3. Tetrahydroaldosterone (THAldo) excretion was readily detectable and did not alter significantly between phases (26.5, 23.5 and 28.5 nmol/24 h, respectively; P = 0.474). 18-Hydroxycortisol (18-OHF) excretion was easily detectable in phases 1 and 3 (252.5 and 212 nmol/24 h), falling in phase 2 (12 nmol/24 h). 18-oxoF excretion rates were lower but followed a similar pattern (1.62, 0.085 and 1.785 nmol/24 h in phases 1, 2 and 3, respectively). CONCLUSIONS Significant levels of adrenal steroids are found in adrenalectomized subjects. We speculate that this occurs at extra-adrenal sites or in residual adrenal cortex tissue in an ACTH-independent manner. Our data suggest that aldosterone synthase, acting on cortisol, is the source of 18-oxoF and 18-OHF in these subjects. Further studies of corticosteroid production within adrenalectomized subjects, looking for evidence of adrenal regrowth or residual adrenal tissue, are justified.
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Affiliation(s)
- E M Freel
- Glasgow Cardiovascular Research Centre, University of Glasgow, UK
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31
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Barr M, MacKenzie SM, Friel EC, Holloway CD, Wilkinson DM, Brain NJR, Ingram MC, Fraser R, Brown M, Samani NJ, Caulfield M, Munroe PB, Farrall M, Webster J, Clayton D, Dominiczak AF, Connell JMC, Davies E. Polymorphic Variation in the 11β-Hydroxylase Gene Associates With Reduced 11-Hydroxylase Efficiency. Hypertension 2007; 49:113-9. [PMID: 17075029 DOI: 10.1161/01.hyp.0000249904.93940.7a] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The −344 C/T and intron 2 conversion variants in the CYP11B2 gene, encoding aldosterone synthase, have been associated with markers of impaired 11β-hydroxylase activity. We hypothesize that this association is because of variations in the adjacent 11β-hydroxylase gene (CYP11B1) and arises through linkage disequilibrium between CYP11B1 and CYP11B2. The pattern of variation across the entire CYP11B locus was determined by sequencing 26 normotensive subjects stratified by and homozygous for the −344 and intron conversion variants. Eighty-three variants associated with −344 and intron conversion were identified. Haplotype analysis revealed 4 common haplotypes, accounting for 68% of chromosomes, confirming strong linkage disequilibrium across the region. Two novel CYP11B1 polymorphisms upstream of the coding region (−1889 G/T and −1859 A/G) were identified as contributing to the common haplotypes. Given the potential for such mutations to affect transcriptional regulation of CYP11B1, these were analyzed further. A total of 512 hypertensive subjects from the British Genetics of Hypertension Study population were genotyped for these polymorphisms. A significant association was identified between the −1889 polymorphism and urinary tetrahydrodeoxycortisol/total cortisol metabolite ratio, indicating reduced 11β-hydroxylase efficiency. A similar pattern was observed for the −1859 polymorphism, but this did not achieve statistical significance. Functional studies in vitro using luciferase reporter gene constructs show that these polymorphisms significantly alter the transcriptional response of CYP11B1 to stimulation by adrenocorticotropic hormone or forskolin. This study strongly suggests that the impaired 11β-hydroxylase efficiency associated previously with the CYP11B2 −344 and intron conversion variants is because of linkage with these newly identified polymorphisms in CYP11B1.
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Affiliation(s)
- Marianne Barr
- British Heart Foundation Glasgow Cardiovascular Research Centre, University of Glasgow, UK
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Kernohan AFB, Sattar N, Hilditch T, Cleland SJ, Small M, Lumsden MA, Connell JMC, Petrie JR. Effects of low-dose continuous combined hormone replacement therapy on glucose homeostasis and markers of cardiovascular risk in women with type 2 diabetes. Clin Endocrinol (Oxf) 2007; 66:27-34. [PMID: 17201798 DOI: 10.1111/j.1365-2265.2006.02679.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND Low-dose hormone replacement therapy (HRT) has attracted interest for the treatment of postmenopausal symptoms in diabetes because of concerns about increased risk of coronary heart disease (CHD) and stroke with conventional HRT containing conjugated equine oestrogens (CEEs) and medroxyprogesterone acetate (MPA). OBJECTIVES We assessed the effects on glucose homeostasis and cardiovascular risk factors of continuous oral 17beta oestradiol (1 mg) and norethisterone (0.5 mg) in postmenopausal women with type 2 diabetes. DESIGN Double-blind, randomized placebo-controlled trial. ASSESSMENTS Hyperinsulinaemic isoglycaemic clamp and cardiovascular risk factors were assessed before and after 3 months of treatment. RESULTS Twenty-eight women completed the study. HRT decreased fasting glucose compared with placebo [-9.4% with HRT vs.+2.3% for placebo, 95% confidence interval (CI) -23.2 to -0.3] and total cholesterol (-13.7 vs.+1.0%, 95% CI -22.4 to -3.1%) No significant effect was seen on metabolic clearance rate of glucose, glycated haemoglobin (HbA1c), triglycerides, high density lipoprotein (HDL)-cholesterol or C-reactive protein (CRP). CONCLUSIONS In women with type 2 diabetes, low-dose HRT decreased fasting glucose and total cholesterol without detectable adverse effects on glucose clearance, triglycerides and CRP as reported with conventional HRT.
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Affiliation(s)
- A F B Kernohan
- Division of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, UK.
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Barr M, MacKenzie SM, Wilkinson DM, Holloway CD, Friel EC, Miller S, MacDonald T, Fraser R, Connell JMC, Davies E. Functional effects of genetic variants in the 11beta-hydroxylase (CYP11B1) gene. Clin Endocrinol (Oxf) 2006; 65:816-25. [PMID: 17121536 DOI: 10.1111/j.1365-2265.2006.02673.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
OBJECTIVE We previously described an association between the -344C/T 5'-untranslated region (UTR) polymorphism in the CYP11B2 (aldosterone synthase) gene and hypertension with a raised aldosterone to renin ratio (ARR); the same genetic variant is also associated with impaired adrenal 11beta-hydroxylase efficiency. The -344 polymorphism does not seem to be functional, so is likely to be in linkage with variants in CYP11B1 that determine the associated variation in 11beta-hydroxylase efficiency. We therefore aimed to determine whether there is an association between CYP11B1 variants and hypertension and/or an altered ARR. DESIGN AND MEASUREMENTS We screened 160 subjects divided into four groups, normotensive controls, unselected hypertensive subjects, and hypertensive subjects with either a high (> or = 750) or low ARR (< or = 200), for variants in the coding region of CYP11B1 by single-stranded conformation polymorphism (SSCP) and direct sequencing. The effects of these variants on enzyme function were assessed by conversion of 11-deoxycortisol to cortisol and 11-deoxycorticosterone (DOC) to corticosterone. RESULTS Eight novel missense mutations were identified in the CYP11B1 gene that alter the encoded amino acids: R43Q, L83S, H125R, P135S, F139L, L158P, L186V and T196A. In each case they were heterozygous changes. However, no mutations were identified that could account for hypertension and/or a raised ARR. The variants L158P and L83S severely impaired enzyme function while R43Q, F139L, P135S and T196A enzymes resulted in product levels that were approximately 30-50% that of wild-type levels. The variant enzymes H125R and L186V resulted in substrate-specific alterations in enzyme function. H125R decreased conversion of 11-deoxycortisol to cortisol and L186V increased 11-deoxycortisol conversion. Neither had an effect on the conversion of DOC to corticosterone. CONCLUSION No variants were identified in the coding region of CYP11B1 that could account for hypertension and/or a raised ARR. However, this in vitro study identifies the importance of these affected residues to enzyme function and will inform subsequent studies of structure-function relationships.
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Affiliation(s)
- Marianne Barr
- Division of Cardiovascular and Medical Sciences, BHF Glasgow Cardiovascular Research Centre, University of Glasgow, Glasgow, UK
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Imrie H, Freel M, Mayosi BM, Davies E, Fraser R, Ingram M, Cordell HJ, Farrall M, Avery PJ, Watkins H, Keavney B, Connell JMC. Association between aldosterone production and variation in the 11beta-hydroxylase (CYP11B1) gene. J Clin Endocrinol Metab 2006; 91:5051-6. [PMID: 16984984 DOI: 10.1210/jc.2006-1481] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
CONTEXT Variation in the region of chromosome 8 including the genes steroid 11beta-hydroxylase (CYP11B1) and aldosterone synthase (CYP11B2) influences mineralocorticoid and glucocorticoid metabolism. However, the relative importance of polymorphisms in CYP11B1 and CYP11B2 in determining these phenotypes is unknown. OBJECTIVE Our objective was to investigate genetic influences of the CYP11B1 and CYP11B2 genes on mineralocorticoid metabolism. DESIGN We measured 24-h urinary excretion of the key metabolites of the principal mineralocorticoids, glucocorticoids and androgens secreted by the adrenal cortex. We genotyped polymorphisms spanning the CYP11B1 and CYP11B2 genes, which together capture all common variations at the locus. PARTICIPANTS Participants included 573 members of 105 British Caucasian families ascertained on a hypertensive proband. MAIN OUTCOME MEASURES We assessed heritability of urinary tetrahydroaldosterone (THAldo) excretion and association of THAldo excretion with genotype. RESULTS The heritability of THAldo excretion was 52% (P < 10(-6)). There was significant association between THAldo and genotype at several of the CYP11B1/B2 polymorphisms. The strongest association was observed at the rs6387 (2803A/G) polymorphism in intron 3 of CYP11B1 (P = 0.0004). Association followed a codominant model with a 21% higher THAldo excretion per G allele. Genotype at rs6387 accounted for 2.1% of the total population variability of THAldo. We found significant association between THAldo excretion and urinary total androgen excretion, urinary tetrahydrodeoxycortisol level, and urinary cortisol metabolites (all P < 0.001). CONCLUSIONS Aldosterone synthesis is highly heritable and is affected by genotype at CYP11B1. Our findings support the hypothesis that genetically determined differences in 11-hydroxylation efficiency can have downstream effects on mineralocorticoid synthesis. Such effects may be of relevance to the development of low-renin essential hypertension.
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Affiliation(s)
- Helen Imrie
- Institute of Human Genetics, Central Parkway, Newcastle NE1 3BZ, United Kingdom
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Freel EM, Connell JMC. Diagnosis of adenomatous primary aldosteronism in a patient with severe hypertension. ACTA ACUST UNITED AC 2006; 1:111-5; quiz following 115. [PMID: 16929379 DOI: 10.1038/ncpendmet0047] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2005] [Accepted: 09/20/2005] [Indexed: 11/09/2022]
Abstract
BACKGROUND A 27-year-old woman presented to her primary-care physician with severe hypertension after complaining of fatigue over the preceding months. She was otherwise asymptomatic. She was referred to a hypertension clinic and was found to be hypokalemic. She was immediately commenced on amlodipine, with atenolol added 2 weeks later. After 4 weeks of this drug therapy, her hypertension persisted and investigations to exclude secondary causes of hypertension were performed. INVESTIGATIONS Aldosterone and renin levels were measured under controlled conditions and the results expressed as an aldosterone-to-renin ratio. CT of the adrenal glands was also performed. DIAGNOSIS Adenomatous primary aldosteronism (Conn's syndrome). MANAGEMENT The patient was initially treated with spironolactone before undergoing a laparoscopic left adrenalectomy.
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Gaukrodger N, Mayosi BM, Imrie H, Avery P, Baker M, Connell JMC, Watkins H, Farrall M, Keavney B. A rare variant of the leptin gene has large effects on blood pressure and carotid intima-medial thickness: a study of 1428 individuals in 248 families. J Med Genet 2006; 42:474-8. [PMID: 15937081 PMCID: PMC1736073 DOI: 10.1136/jmg.2004.027631] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
BACKGROUND Rare mutations in the leptin (LEP) gene cause severe obesity. Common polymorphisms of LEP have been associated with obesity, but their association with cardiovascular disease has been little studied. We have examined the impact of both common and rare polymorphisms of the LEP gene on blood pressure (BP), subclinical atherosclerosis as measured by carotid intima-medial thickness (CIMT), and body mass index (BMI) in a large family study. METHODS Five polymorphisms spanning LEP were typed in 1428 individuals from 248 nuclear families. BP, CIMT, BMI, and plasma leptin were measured. RESULTS The polymorphisms typed captured all common haplotypes present at LEP. There was strong association between a rare polymorphism in the 3' untranslated region of LEP (C538T) and both pulse pressure (p = 0.0001) and CIMT (p = 0.008). C/T heterozygotes had a 22% lower pulse pressure and a 17% lower CIMT than C/C homozygotes. The polymorphism accounted for 3-5% of the population variation in pulse pressure and CIMT. There was no association between any LEP polymorphism and either BMI or plasma leptin level. CONCLUSIONS This large family study shows that the rare T allele at the C538T polymorphism of LEP substantially influences pulse pressure and CIMT, but does not appear to exert this effect through actions on plasma leptin level or BMI. This suggests that autocrine or paracrine effects in vascular tissue may be important physiological functions of leptin. This study also provides evidence that rare polymorphisms of particular genes may have substantial effects within the normal range of certain quantitative traits.
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Affiliation(s)
- N Gaukrodger
- Institute of Human Genetics, Central Parkway, Newcastle upon Tyne, NE1 3BZ, UK
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Nazir FS, Alem M, Small M, Connell JMC, Lees KR, Walters MR, Cleland SJ. Blunted response to systemic nitric oxide synthase inhibition in the cerebral circulation of patients with Type 2 diabetes. Diabet Med 2006; 23:398-402. [PMID: 16620268 DOI: 10.1111/j.1464-5491.2006.01815.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
AIMS Diabetes is a major risk factor for stroke, but the mechanisms that impart the excess risk are unclear. Endothelial dysfunction, which has been demonstrated in the coronary and peripheral vasculature of diabetic patients, is an important early marker of vascular disease. However, the effect of diabetes on cerebrovascular endothelium has not been examined. We sought to investigate the effect of diabetes on basal cerebrovascular endothelial function as assessed by response to the nitric oxide synthase (NOS) inhibitor NG-monomethyl-L-arginine (L-NMMA). METHODS Fourteen men with Type 2 diabetes and 15 age-matched male control subjects were recruited. The participants had no clinically evident vascular disease and were taking no vasoactive or lipid-lowering medication. Each received a single 15-min intravenous infusion of L-NMMA (0.8 mol/kg/min). Cerebral blood flow was assessed by colour Doppler imaging of the internal carotid artery (ICA) at 10-min intervals for 20 min prior to and following the infusion. Middle cerebral artery velocity (MCAv) was assessed by transtemporal Doppler ultrasound at the same time points. RESULTS L-NMMA produced a mean reduction in ICA flow area under curve (AUC) in the control group of 12.8 +/- 17.8% compared with a 2.1 +/- 21.7% reduction in the group with diabetes (P < 0.05), indicating blunted basal cerebrovascular response to NOS inhibition in the diabetic group. There was no significant change in MCAv following L-NMMA in either group. Mean +/- sd MAP rose 6.4 +/- 4.2 mmHg in the control group vs. 8.8 +/- 3.5 mmHg in the diabetic group [P = not significant (NS)]. No adverse event or symptom was reported. CONCLUSIONS Response to NOS inhibition is impaired in the cerebral circulation of patients with diabetes. This observation is consistent with the elevated cerebrovascular risk reported in this population, and may represent a future therapeutic target in stroke prevention.
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Affiliation(s)
- F S Nazir
- Division of Cardiovascular and Medical Sciences, University of Glasgow, Glasgow, UK
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Ye P, Kenyon CJ, MacKenzie SM, Jong AS, Miller C, Gray GA, Wallace A, Ryding AS, Mullins JJ, McBride MW, Graham D, Fraser R, Connell JMC, Davies E. The aldosterone synthase (CYP11B2) and 11beta-hydroxylase (CYP11B1) genes are not expressed in the rat heart. Endocrinology 2005; 146:5287-93. [PMID: 16179417 DOI: 10.1210/en.2005-0370] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Aldosterone synthase (CYP11B2) and 11beta-hydroxylase (CYP11B1) catalyze the production of aldosterone and corticosterone, respectively, in the rat adrenal cortex. Recently, there has been some debate as to whether these corticosteroids are also produced in the hearts of rodents and humans, possibly contributing to the development of hypertrophy and myocardial fibrosis. To investigate this, we have used our established, highly sensitive real-time quantitative RT-PCR method to measure CYP11B1 and CYP11B2 mRNA levels in adrenal and cardiac tissue from several rat models of cardiovascular pathology. We have also studied isolated adult rat ventricular myocytes treated with angiotensin II and ACTH. Total RNA was isolated from the adrenal and cardiac tissue of 1) male Wistar rats with heart failure induced by coronary artery ligation and sham-operated controls; 2) stroke-prone spontaneously hypertensive rats and Wistar Kyoto rats as controls; 3) cyp1a1Ren-2 transgenic rats and Fischer controls; 4) isolated adult Sprague-Dawley ventricular myocytes incubated with 11-deoxycorticosterone (DOC), DOC plus angiotensin II, or DOC plus ACTH. Adrenal CYP11B2 expression was significantly increased in transgenic rats compared with Fischer controls (1.3 x 10(9)+/- 1.2 x 10(9) vs. 2.1 x 10(7) +/- 7.0 x 10(6) copies/microg RNA; P < 0.05). There were no other significant differences in adrenal CYP11B2 or CYP11B1 expression between the model animals and their respective controls. Cardiac CYP11B1 and CYP11B2 mRNA transcript levels from all in vivo and in vitro groups were never greater than 100 copies per microgram total RNA and therefore too low to be detected reproducibly. This suggests that cardiac corticosteroid production is unlikely to be of any physiological or pathological significance.
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Affiliation(s)
- P Ye
- Division of Cardiovascular and Medical Sciences, Western Infirmary, Glasgow, UK
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Baker M, Gaukrodger N, Mayosi BM, Imrie H, Farrall M, Watkins H, Connell JMC, Avery PJ, Keavney B. Association between common polymorphisms of the proopiomelanocortin gene and body fat distribution: a family study. Diabetes 2005; 54:2492-6. [PMID: 16046320 DOI: 10.2337/diabetes.54.8.2492] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Rare mutations in the proopiomelanocortin (POMC) gene cause severe early-onset childhood obesity. However, it is unknown whether common variants in POMC are responsible for variation in body weight or fat distribution within the commonly observed range in the population. We tested for association between three polymorphisms spanning the POMC gene and obesity phenotypes in 1,428 members of 248 families. There was significant association between genotypes at the C8246T (P < 0.0001) and C1032G (P = 0.003) polymorphisms and waist-to-hip ratio (WHR) corrected for age, sex, smoking, exercise, and alcohol consumption. Each T allele at C8246T (or G allele at C1032G) was associated with a 0.2-SD-higher WHR in a codominant fashion. When WHR was additionally corrected for BMI, thus providing a measure of body fat distribution throughout the range of BMI, there remained significant evidence for association with both markers that was of similar magnitude and statistical significance. There was no association between genotype at any polymorphism and BMI or plasma leptin level. These data show that genetic variants at the POMC locus influence body fat distribution within the normal range, suggesting a novel role for POMC in metabolic regulation.
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Affiliation(s)
- Michelle Baker
- Institute of Human Genetics, Central Parkway, Newcastle NE1 3BZ, UK
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Stergiou GS, Efstathiou SP, Inglis GC, Connell JMC, McInnes GT, Mountokalakis TD. Association of renin–angiotensin system gene polymorphisms with antihypertensive responses to angiotensin-converting enzyme inhibition or angiotensin receptor blockade. J Hum Hypertens 2005; 19:971-4. [PMID: 16049518 DOI: 10.1038/sj.jhh.1001918] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Abstract
Classically, aldosterone is synthesised in the adrenal zona glomerulosa and binds to specific mineralocorticoid receptors located in the cytosol of target epithelial cells. Translocation of the resulting steroid receptor complex to the cell nucleus modulates gene expression and translation of specific 'aldosterone-induced' proteins that regulate electrolyte and fluid balance. However, non-epithelial and rapid non-genomic actions of aldosterone have also been described that account for a variety of actions of aldosterone that contribute to blood pressure homeostasis. These include key actions on endothelial cells and on cardiac tissue. There is also evidence that aldosterone can be synthesised in other tissues; the most convincing evidence relates to the central nervous system. However, suggestions that aldosterone is produced in the heart remain controversial, and adrenal derived aldosterone is the principal source of circulating and locally available hormone. Recent studies have shown major therapeutic benefits of mineralocorticoid receptor antagonism in cardiac failure, which emphasise the importance of aldosterone in causing adverse cardiovascular pathophysiological effects. Additional evidence demonstrates that aldosterone levels predict development of high blood pressure in normotensive subjects, while it is now clear that increased aldosterone action contributes to hypertension and cardiovascular damage in approximately 10% of patients with established hypertension. These new findings highlight the role of aldosterone as a key cardiovascular hormone and extend our understanding of its role in determining adverse cardiovascular outcomes.
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Affiliation(s)
- John M C Connell
- MRC Blood Pressure Group, Division of Cardiovascular and Medical Sciences, University of Glasgow, Gardiner Institute, Western Infirmary, Glasgow G11 6NT, UK.
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McCallum RW, Sainsbury CAR, Spiers A, Dominiczak AF, Petrie JR, Sattar N, Connell JMC. Growth hormone replacement reduces C-reactive protein and large-artery stiffness but does not alter endothelial function in patients with adult growth hormone deficiency. Clin Endocrinol (Oxf) 2005; 62:473-9. [PMID: 15807879 DOI: 10.1111/j.1365-2265.2005.02245.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Hypopituitary patients have an increased risk of vascular mortality that may relate to growth hormone deficiency (GHD). We investigated the effects of 6 months of GH therapy on large- and small-artery function and high-sensitivity C-reactive protein (hsCRP) in a cohort of GH-deficient patients. Sixteen hypopituitary patients were randomized to 6 months of GH therapy or no treatment, then vice versa. hsCRP, 24-h blood pressure (BP) and pulse wave velocity (PWV) were measured and resistance arteries were used to construct concentration-response curves to endothelium-dependent and -independent agents. GH therapy increased IGF-1 from 60 +/- 7.2 to 167 +/- 16.2 microg/l [confidence interval (CI) 94.9, 138.8, P < 0.001]. hsCRP declined after 6 months of GH from 3.8 +/- 0.88 to 2.0 +/- 0.49 mg/l (CI 0.73, 3.57, P = 0.006). Mean arterial BP fell from 91.7 +/- 1.5 to 89.3 +/- 1.2 mmHg (CI 0.81, 4.07, P = 0.005), as did PWV (8.1 +/- 0.4 to 6.7 +/- 0.5 m/s). The decline in PWV correlated with the decline in hsCRP (r = 0.68, P = 0.01). Resistance artery function was unchanged after GH therapy. GH replacement may lead to differentially altered production of vasorelaxant agents from the endothelium of large and small arteries. Reduction in vascular inflammation may be associated with reduced vascular risk.
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Affiliation(s)
- Roland W McCallum
- Division of Cardiovascular and Medical Sciences, University of Glasgow, Western Infirmary, Glasgow G11 6NT, UK
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Collison M, James DJ, Graham D, Holman GD, Connell JMC, Dominiczak AF, Gould GW, Salt IP. Reduced insulin-stimulated GLUT4 bioavailability in stroke-prone spontaneously hypertensive rats. Diabetologia 2005; 48:539-46. [PMID: 15729573 DOI: 10.1007/s00125-005-1674-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2004] [Accepted: 10/29/2004] [Indexed: 10/25/2022]
Abstract
AIMS/HYPOTHESIS Insulin-stimulated glucose transport is impaired in a genetic model of hypertension, the stroke-prone spontaneously hypertensive rat (SHRSP), yet the molecular mechanisms that underlie this defect in the animals remain unclear. METHODS We examined the effects of insulin on the trafficking of the insulin-responsive glucose transporter GLUT4 to the plasma membrane in isolated adipocytes from SHRSP and normotensive control Wistar-Kyoto (WKY) rats. RESULTS Treatment of isolated adipocytes with insulin resulted in trafficking of GLUT4 to the plasma membrane. There was no significant difference in the magnitude of insulin-stimulated GLUT4 trafficking from intracellular membranes to the plasma membrane between strains. In contrast, we demonstrated that there is a significant reduction in GLUT4 accessible to the glucose photolabel Bio-LC-ATB-BGPA at the plasma membrane of SHRSP adipocytes compared with control rats. CONCLUSIONS/INTERPRETATION We propose that a large proportion of GLUT4 translocated to the plasma membrane in response to insulin is not able to bind substrate and catalyse transport in the SHRSP. Therefore, there is a reduction in bioavailable GLUT4 in SHRSP animals that is likely to account, at least in part, for the reduced insulin-stimulated glucose uptake.
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Affiliation(s)
- M Collison
- The Henry Wellcome Laboratory of Cell Biology, Division of Biochemistry and Molecular Biology, Institute of Biomedical and Life Sciences, Davidson Building, University of Glasgow, Glasgow, G12 8QQ, UK
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Sainsbury CAR, Sattar N, Connell JMC, Hillier C, Petrie JR. Non-esterified fatty acids impair endothelium-dependent vasodilation in rat mesenteric resistance vessels. Clin Sci (Lond) 2005; 107:625-9. [PMID: 15367101 DOI: 10.1042/cs20040140] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Elevated circulating levels of NEFAs (non-esterified fatty acids) are associated with states of insulin resistance and increased risk of vascular disease. Previous animal and human studies have demonstrated NEFA-induced endothelial dysfunction of large conduit arteries, reversible by the antioxidant ascorbic acid. We therefore investigated the effect of NEFAs on carbachol-induced endothelium-dependent vasodilation of rat resistance arteries in vitro using the technique of wire myography. In addition, we investigated the effect of co-incubation of NEFAs and ascorbic acid. Cumulative concentration-response curves to carbachol (endothelium-dependent vasodilation) and SNAP (S-nitroso-N-acetyl-DL-penicillamine; endothelium-independent vasodilation) were constructed. Those to carbachol were repeated following a 30 min incubation with either oleic acid (10(-4) M) or palmitic acid (10(-4) M), demonstrating significant impairment of endothelium-dependent vasodilation with both [P<0.05, comparison of pD2 values (the negative log concentration of agonist required to effect a 50% response)]. A cumulative concentration-response curve to carbachol was repeated following co-incubation with palmitic acid (10(-4) M) and the antioxidant ascorbic acid (10(-5) M), demonstrating an abolition of the previously observed endothelial dysfunction induced by palmitic acid. There was no impairment of vasodilation to SNAP following NEFA incubation. We conclude that NEFAs directly impair endothelial function in rat resistance arteries via an increase in oxidative stress at the vascular endothelium.
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Ritchie SA, Ewart MA, Perry CG, Connell JMC, Salt IP. The role of insulin and the adipocytokines in regulation of vascular endothelial function. Clin Sci (Lond) 2004; 107:519-32. [PMID: 15324298 DOI: 10.1042/cs20040190] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Vascular integrity in the healthy endothelium is maintained through the release of a variety of paracrine factors such as NO (nitric oxide). Endothelial dysfunction, characterized by reduced NO bioavailability, is associated with obesity, insulin resistance and Type II diabetes. Insulin has been demonstrated to have direct effects on the endothelium to increase NO bioavailability. Therefore altered insulin signalling in the endothelium represents a candidate mechanism underlying the association between insulin resistance and endothelial dysfunction. In recent years, it has become apparent that insulin sensitivity is regulated by the adipocytokines, a group of bioactive proteins secreted by adipose tissue. Secretion of adipocytokines is altered in obese individuals and there is increasing evidence that the adipocytokines have direct effects on the vascular endothelium. A number of current antidiabetic strategies have been demonstrated to have beneficial effects on endothelial function and to alter adipocytokine concentrations in addition to their effects on glucose homoeostasis. In this review we will explore the notion that the association between insulin resistance and endothelial dysfunction is accounted for by adipocytokine action on the endothelium. In addition, we examine the effects of weight loss, exercise and antidiabetic drugs on adipocytokine availability and endothelial function.
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Affiliation(s)
- Stuart A Ritchie
- Henry Wellcome Laboratory of Cell Biology, Division of Biochemistry and Molecular Biology, Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, UK
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Kennon B, Ingram MC, Friel EC, Anderson NH, MacKenzie SM, Davies E, Shakerdi L, Wallace AM, Fraser R, Connell JMC. Aldosterone synthase gene variation and adrenocortical response to sodium status, angiotensin II and ACTH in normal male subjects. Clin Endocrinol (Oxf) 2004; 61:174-81. [PMID: 15272911 DOI: 10.1111/j.1365-2265.2004.02073.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVE Aldosterone synthase, a key enzyme in the terminal steps of aldosterone synthesis, is encoded by the CYP11B2 gene. A polymorphism in the 5' coding region of this gene (-344 C/T) is associated with hypertension, particularly with elevation of the aldosterone to renin ratio. A second polymorphism (a conversion in intron 2 to resemble that of the neighbouring 11beta-hydroxylase (CYP11B1) gene) is found in close linkage dysequilibrium with the variant at -344 C/T. The mechanism by which these variants predispose to cardiovascular disease and the precise intermediate phenotype associated with them remains speculative. DESIGN We performed a focused physiological study in normal volunteers stratified by CYP11B2 genotype. PATIENTS Twenty-three subjects homozygous for the T allele and 21 homozygous for the C allele of the -344 C/T polymorphism of CYP11B2 were studied. MEASUREMENTS Basal and angiotensin II stimulated plasma and 24-h urinary steroid excretion during low (60 mmol/day) and high (160 mmol/day) sodium intake and plasma steroids after ACTH stimulation were measured. RESULTS No influence of polymorphic variation on basal or stimulated plasma cortisol or aldosterone or other plasma steroid concentrations during either dietary phase was seen. However, excretion of tetrahydro-11-deoxycortisol (the urinary metabolite of 11-deoxycortisol), which is the precursor of cortisol) was increased in TT subjects during sodium restriction, consistent with impairment of zona fasciculata 11beta-hydroxylation. CONCLUSIONS We conclude that this polymorphism has no major influence on normal zona glomerulosa function but is associated with a change in 11beta-hydroxylation in the zona fasciculata. The mechanism remains uncertain, but alteration of 11-deoxycortisol levels without change in cortisol suggests altered efficiency of 11beta-hydroxylation. In the long term, this may lead to a minor but chronic increase in ACTH drive to the gland, which may have consequences for steroid synthesis and predispose to the risk of cardiovascular disease.
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Affiliation(s)
- Brian Kennon
- MRC Blood Pressure Group, Division of Cardiovascular and Medical Sciences, University of Glasgow, Western Infirmary, Glasgow, UK
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Wallace AM, Banfield E, Ingram M, Fraser R, Swan L, Hillis WS, Connell JMC. Glucocorticoids contribute to the heritability of leptin in Scottish adult female twins. Clin Endocrinol (Oxf) 2004; 61:149-54. [PMID: 15212658 DOI: 10.1111/j.1365-2265.2004.02068.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
OBJECTIVE The precise interactions between glucocorticoids and leptin are complex and poorly understood. The aim of the study was to investigate whether the glucocorticoid/leptin interaction is influenced by shared environmental or genetic factors. DESIGN We investigated the heritability of body mass index (BMI), circulating leptin and urinary glucocorticoid metabolites [tetrahydrocortisol (THF), alloTHF and tetrahydrocortisone (THE)] in 54 monozygotic (MZ) and 39 dizygotic (DZ) female twins. Analysis was performed using a structural equation modelling package Mx, developed by Neale. RESULTS Leptin and BMI showed substantial heritability (68.3% and 71.3%, respectively). Bivariate analysis indicated that the genetic determinants of BMI and leptin are partly shared. Total cortisol metabolites (THF + alloTHF + THE), the (THE + alloTHF)/THE ratio [a marker of 11beta-hydroxysteroid dehydrogenase (11HSD) activity] and the alloTHF/THF ratio (marker for 5alpha-reductase activity) followed an environmental pattern. The heritability of leptin was significantly lowered to 63.8% (P = 0.012) when values were corrected for the influence of total cortisol metabolites but unaffected by markers of 11HSD and 5alpha-reductase activity. CONCLUSIONS We confirm that the genetic influence on both BMI and the circulating leptin concentration is substantial and show that these genetic determinants are highly correlated. These genetic factors, which are more likely to be dominant than additive, can be modestly but significantly modified by urinary total cortisol metabolites implying an adrenal influence.
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Affiliation(s)
- A M Wallace
- Department of Clinical Biochemistry, Royal Infirmary, Glasgow, UK.
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James DJ, Salaün C, Brandie FM, Connell JMC, Chamberlain LH. Neomycin Prevents the Wortmannin Inhibition of Insulin-stimulated Glut4 Translocation and Glucose Transport in 3T3-L1 Adipocytes. J Biol Chem 2004; 279:20567-70. [PMID: 15024008 DOI: 10.1074/jbc.c400096200] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Insulin stimulates the movement of the facilitative glucose transporter glucose transporter-4 (Glut4) from an intracellular compartment to the plasma membrane in adipocytes and muscle cells, resulting in an increased rate of glucose uptake. Insulin-stimulated Glut4 translocation and glucose transport are abolished by wortmannin, a specific inhibitor of phosphatidylinositol 3'-kinase (PI3K). Here, we demonstrate that neomycin, a drug that masks the cellular substrate of PI3K, phosphatidylinositol 4,5-bisphosphate (PIP), prevents wortmannin inhibition of insulin-stimulated (2)Glut4 translocation and glucose transport without activating protein kinase B, a downstream effector of PI3K. These results suggest that PIP(2) may have an important regulatory function in insulin-stimulated Glut4 translocation and glucose transport.
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Affiliation(s)
- Declan J James
- Henry Welcome Laboratory of Cell Biology, Division of Biochemistry and Molecular Biology, Institute of Biomedical and Life Sciences, Davidson Building, University of Glasgow, Glasgow G12 8QQ, Scotland, UK
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Connell JMC, Fraser R, MacKenzie SM, Friel EC, Ingram MC, Holloway CD, Davies E. The impact of polymorphisms in the gene encoding aldosterone synthase (CYP11B2) on steroid synthesis and blood pressure regulation. Mol Cell Endocrinol 2004; 217:243-7. [PMID: 15134824 DOI: 10.1016/j.mce.2003.10.025] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
The terminal stages in the synthesis of aldosterone and cortisol are catalysed by the enzymes aldosterone synthase and 11beta-hydroxylase respectively. We have previously reported that polymorphic variation in the 5' promoter region (-344C/T) of the gene encoding aldosterone synthase (CYP11B2) is associated with increased aldosterone metabolite excretion and with hypertension associated with a raised aldosterone to renin ratio (ARR). Additionally, basal and ACTH-stimulated plasma levels of 11-deoxycortisol, the precursor of cortisol, are higher in subjects carrying the T-allelic variant. We have now identified in a family study (573 individuals from 105 extended families ascertained through a hypertensive proband) that excretion of the main metabolite of this steroid (tetrahydro-11-deoxycortisol, THS) is heritable (19.4%) and that the T-allele of CYP11B2 is more strongly associated with higher THS levels than the C-allele. Raised plasma and urinary levels of 11-deoxycortisol suggest that there is relative inefficiency of 11beta-hydroxylation in the zona fasciculata; the P450 enzyme responsible for this step is encoded by the gene CYP11B1, which is highly homologous with and adjacent to CYP11B2. The association of genetic variation in the promoter of CYP11B2 which, in the adrenal cortex, is only expressed in zona glomerulosa, and zona fasciculata 11beta-hydroxylation function is paradoxical. There may be linkage dys-equilibrium between this polymorphism and a quantitative trait locus (QTL) in CYP11B1. Chronic alteration of 11beta-hydroxylase activity may increase ACTH drive to the adrenal cortex, altering the regulation of aldosterone synthesis. This may explain, at least partly, the association between CYP11B2 polymorphisms and hypertension.
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Affiliation(s)
- John M C Connell
- MRC Blood Pressure Group, Western Infirmary, Glasgow G11 6NT, Scotland, UK.
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McEleavy OD, McCallum RW, Petrie JR, Small M, Connell JMC, Sattar N, Cleland SJ. Higher carotid-radial pulse wave velocity in healthy offspring of patients with Type 2 diabetes. Diabet Med 2004; 21:262-6. [PMID: 15008837 DOI: 10.1111/j.1464-5491.2004.01127.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
AIMS To determine whether carotid-radial pulse wave velocity (crPWV), a simple non-invasive measurement of muscular artery structure and function, is increased in offspring of patients with Type 2 diabetes compared with well-matched controls with no family history of diabetes. Serum levels of intercellular adhesion molecule-1 (sICAM-1) were also examined. METHODS Offspring (n = 19, M = 8) were recruited via contact with patients attending clinics. Controls (n = 19, M = 8) were recruited by advertisement. crPWV was measured using COMPLIOR. Blood pressure and heart rate were determined and fasting blood taken for measurement of metabolic and endothelial parameters. RESULTS Offspring and controls were well matched [mean (sd)] for age [33.1 (9.6) vs. 32.8 (9.5) years], body mass index [24.8 (4.9) vs. 24.3 (3.4) kg/m2], waist circumference [78.3 (2.3) vs. 76.3 (2.5) cm], and systolic blood pressure [120 (9.3) vs. 119 (14.2) mmHg]. crPWV was 10% higher in the offspring [9.94 (1.3) m/s] compared with controls [9.01 (1.2) m/s, P = 0.02] despite similar pulse pressure [52 (10.5) vs. 53.5 (9.3) mmHg] and resting heart rate [71 (8.7) vs. 69 (14.0) beats/min]. They also showed a trend toward higher sICAM-1 [217 (55) vs. 188 (40) ng/ml, P = 0.07] concentrations which were also strongly correlated to crPWV in offspring (r = 0.63, P = 0.004). CONCLUSIONS Vascular dysfunction in the form of increased muscular artery stiffness is present from an early stage in subjects at higher risk of developing diabetes. This may be secondary to impaired activation of endothelial signalling pathways in the context of inherited insulin resistance.
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Affiliation(s)
- O D McEleavy
- Division of Cardiovascular & Medical Sciences, University of Glasgow, UK
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