Brian R. Walker

Bio: Brian R. Walker is an academic researcher from Newcastle University. The author has contributed to research in topics: Glucocorticoid & Adipose tissue. The author has an hindex of 87, co-authored 407 publications receiving 26694 citations. Previous affiliations of Brian R. Walker include Queen's University & British Heart Foundation.

Minireview: 11β-Hydroxysteroid Dehydrogenase Type 1— A Tissue-Specific Amplifier of Glucocorticoid Action1

Abstract: 11β-hydroxysteroid dehydrogenases (11β-HSDs) catalyze the interconversion of active glucocorticoids (cortisol, corticosterone) and inert 11-keto forms (cortisone, 11-dehydrocorticosterone). 11β-HSD type 2 has a well recognized function as a potent dehydrogenase that rapidly inactivates glucocorticoids, thus allowing aldosterone selective access to otherwise nonselective mineralocorticoid receptors in the distal nephron. In contrast, the function of 11β-HSD type 1 has, until recently, been little understood. 11β-HSD1 is an ostensibly reversible oxidoreductase in vitro, which is expressed in liver, adipose tissue, brain, lung, and other glucocorticoid target tissues. However, increasing data suggest that 11β-HSD1 acts as a predominant 11β-reductase in many intact cells, whole organs, and in vivo. This reaction direction locally regenerates active glucocorticoids within expressing cells, exploiting the substantial circulating levels of inert 11-keto steroids. While the biochemical determinants of the reactio...

Glucocorticoids and insulin resistance: old hormones, new targets

Abstract: Insulin resistance has been proposed as a mediator of the association between risk factors for cardiovascular disease in the population. The clinical syndrome of glucocorticoid excess (Cushing's syndrome) is associated with glucose intolerance, obesity and hypertension. By opposing the actions of insulin, glucocorticoids could contribute to insulin resistance and its association with other cardiovascular risk factors. In this review, we describe briefly the known mechanisms of insulin resistance and highlight the potential mechanisms for the effect of glucocorticoids. We then discuss factors which modulate the influence of glucocorticoids on insulin sensitivity; this highlights a novel therapeutic strategy to manipulate glucocorticoid action which may prove to be a useful tool in treating subjects with insulin resistance. Finally, we describe evidence from human studies that glucocorticoids make an important contribution to the pathophysiology of insulin resistance in the population.

Tissue-specific dysregulation of cortisol metabolism in human obesity.

Abstract: Cortisol has been implicated as a pathophysiological mediator in idiopathic obesity, but circulating cortisol concentrations are not consistently elevated. The tissue-specific responses to cortisol may be influenced as much by local prereceptor metabolism as by circulating concentrations. For example, in liver and adipose tissue cortisol is regenerated from inactive cortisone by 11beta-hydroxysteroid dehydrogenase type 1 (11beta-HSD1). In obese Zucker rats 11beta-HSD1 activity is reduced in liver but enhanced in adipose tissue. This study addressed whether the same tissue-specific disruption of cortisol metabolism occurs in human obesity. 34 men were recruited from the MONICA population study in Northern Sweden to represent a wide range of body composition and insulin insensitivity. Plasma cortisol was measured at 0830h and 1230h, after overnight low-dose dexamethasone suppression, after intravenous corticotropin releasing hormone (CRH), and after oral cortisone administration. Urinary cortisol metabolites were measured in a 24 h sample. A subcutaneous fat biopsy was obtained from 16 participants to measure cortisol metabolism in vitro. Higher body mass index was associated with increased total cortisol metabolite excretion (r = 0.47, p < 0.01), but lower plasma cortisol at 1230 h and after dexamethasone, and no difference in response to CRH. Obese men excreted a greater proportion of glucocorticoid as metabolites of cortisone rather than cortisol (r = 0.43, p < 0.02), and converted less cortisone to cortisol after oral administration (r = 0.49, p < 0.01), suggesting impaired hepatic 11beta-HSD1 activity. By contrast, in vitro 11beta-HSD1 activity in subcutaneous adipose tissue was markedly enhanced in obese men (r = 0.66, p < 0.01). We conclude that in obesity, reactivation of cortisone to cortisol by 11beta-HSD1 in liver is impaired, so that plasma cortisol levels tend to fall, and there may be a compensatory increase in cortisol secretion mediated by a normally functioning hypothalamic-pituitary-adrenal axis. However, changes in 11beta-HSD1 are tissue-specific: strikingly enhanced reactivation of cortisone to cortisol in subcutaneous adipose tissue may exacerbate obesity; and it may be beneficial to inhibit this enzyme in adipose tissue in obese patients.

Taking glucocorticoids by prescription is associated with subsequent cardiovascular disease.

Abstract: In this population-based study, patients receiving dosages of glucocorticoids greater than the equivalent of 7.5 mg of prednisolone per day had substantially higher 1- to 5-year rates of all cardio...

Elevated plasma cortisol concentrations: a link between low birth weight and the insulin resistance syndrome?

Abstract: Recent studies have shown that reduced fetal growth is associated with the development of the insulin resistance syndrome in adult life. The mechanisms are not known. However increased activity of the hypothalamic-pituitary-adrenal axis (HPAA) may underlie this association; the axis is known to be reset by fetal growth retardation in animals, and there is evidence in humans of an association between raised HPAA activity and the insulin resistance syndrome. We have, therefore, examined the relations among size at birth, plasma cortisol concentrations, and components of the insulin resistance syndrome in a sample of healthy men. We measured 0900 h fasting plasma cortisol and corticosteroid-binding globulin levels in 370 men who were born in Hertfordshire, UK, between 1920-1930 and whose birth weights were recorded. Fasting plasma cortisol concentrations varied from 112-702 nmol/L and were related to systolic blood pressure (P = 0.02), fasting and 2-h plasma glucose concentrations after an oral glucose tolerance test (P = 0.0002 and P = 0.04), plasma triglyceride levels (P = 0.009), and insulin resistance (P = 0.006). Plasma cortisol concentrations fell progressively (P = 0.007) from 408 nmol/L in men whose birth weights were 5.5 lb (2.50 kg) or less to 309 nmol/L among those who weighed 9.5 lb (4.31 kg) or more at birth, a trend independent of age and body mass index. These findings suggest that plasma concentrations of cortisol within the normal range could have an important effect on blood pressure and glucose tolerance. Moreover, this study provides the first evidence that intrauterine programming of the HPAA may be a mechanism underlying the association between low birth weight and the insulin resistance syndrome in adult life.

2013 ESH/ESC Guidelines for the management of arterial hypertension: The Task Force for the management of arterial hypertension of the European Society of Hypertension (ESH) and of the European Society of Cardiology (ESC).

Abstract: ABCD : Appropriate Blood pressure Control in Diabetes ABI : ankle–brachial index ABPM : ambulatory blood pressure monitoring ACCESS : Acute Candesartan Cilexetil Therapy in Stroke Survival ACCOMPLISH : Avoiding Cardiovascular Events in Combination Therapy in Patients Living with Systolic Hypertension ACCORD : Action to Control Cardiovascular Risk in Diabetes ACE : angiotensin-converting enzyme ACTIVE I : Atrial Fibrillation Clopidogrel Trial with Irbesartan for Prevention of Vascular Events ADVANCE : Action in Diabetes and Vascular Disease: Preterax and Diamicron-MR Controlled Evaluation AHEAD : Action for HEAlth in Diabetes ALLHAT : Antihypertensive and Lipid-Lowering Treatment to Prevent Heart ATtack ALTITUDE : ALiskiren Trial In Type 2 Diabetes Using Cardio-renal Endpoints ANTIPAF : ANgioTensin II Antagonist In Paroxysmal Atrial Fibrillation APOLLO : A Randomized Controlled Trial of Aliskiren in the Prevention of Major Cardiovascular Events in Elderly People ARB : angiotensin receptor blocker ARIC : Atherosclerosis Risk In Communities ARR : aldosterone renin ratio ASCOT : Anglo-Scandinavian Cardiac Outcomes Trial ASCOT-LLA : Anglo-Scandinavian Cardiac Outcomes Trial—Lipid Lowering Arm ASTRAL : Angioplasty and STenting for Renal Artery Lesions A-V : atrioventricular BB : beta-blocker BMI : body mass index BP : blood pressure BSA : body surface area CA : calcium antagonist CABG : coronary artery bypass graft CAPPP : CAPtopril Prevention Project CAPRAF : CAndesartan in the Prevention of Relapsing Atrial Fibrillation CHD : coronary heart disease CHHIPS : Controlling Hypertension and Hypertension Immediately Post-Stroke CKD : chronic kidney disease CKD-EPI : Chronic Kidney Disease—EPIdemiology collaboration CONVINCE : Controlled ONset Verapamil INvestigation of CV Endpoints CT : computed tomography CV : cardiovascular CVD : cardiovascular disease D : diuretic DASH : Dietary Approaches to Stop Hypertension DBP : diastolic blood pressure DCCT : Diabetes Control and Complications Study DIRECT : DIabetic REtinopathy Candesartan Trials DM : diabetes mellitus DPP-4 : dipeptidyl peptidase 4 EAS : European Atherosclerosis Society EASD : European Association for the Study of Diabetes ECG : electrocardiogram EF : ejection fraction eGFR : estimated glomerular filtration rate ELSA : European Lacidipine Study on Atherosclerosis ESC : European Society of Cardiology ESH : European Society of Hypertension ESRD : end-stage renal disease EXPLOR : Amlodipine–Valsartan Combination Decreases Central Systolic Blood Pressure more Effectively than the Amlodipine–Atenolol Combination FDA : U.S. Food and Drug Administration FEVER : Felodipine EVent Reduction study GISSI-AF : Gruppo Italiano per lo Studio della Sopravvivenza nell'Infarto Miocardico-Atrial Fibrillation HbA1c : glycated haemoglobin HBPM : home blood pressure monitoring HOPE : Heart Outcomes Prevention Evaluation HOT : Hypertension Optimal Treatment HRT : hormone replacement therapy HT : hypertension HYVET : HYpertension in the Very Elderly Trial IMT : intima-media thickness I-PRESERVE : Irbesartan in Heart Failure with Preserved Systolic Function INTERHEART : Effect of Potentially Modifiable Risk Factors associated with Myocardial Infarction in 52 Countries INVEST : INternational VErapamil SR/T Trandolapril ISH : Isolated systolic hypertension JNC : Joint National Committee JUPITER : Justification for the Use of Statins in Primary Prevention: an Intervention Trial Evaluating Rosuvastatin LAVi : left atrial volume index LIFE : Losartan Intervention For Endpoint Reduction in Hypertensives LV : left ventricle/left ventricular LVH : left ventricular hypertrophy LVM : left ventricular mass MDRD : Modification of Diet in Renal Disease MRFIT : Multiple Risk Factor Intervention Trial MRI : magnetic resonance imaging NORDIL : The Nordic Diltiazem Intervention study OC : oral contraceptive OD : organ damage ONTARGET : ONgoing Telmisartan Alone and in Combination with Ramipril Global Endpoint Trial PAD : peripheral artery disease PATHS : Prevention And Treatment of Hypertension Study PCI : percutaneous coronary intervention PPAR : peroxisome proliferator-activated receptor PREVEND : Prevention of REnal and Vascular ENdstage Disease PROFESS : Prevention Regimen for Effectively Avoiding Secondary Strokes PROGRESS : Perindopril Protection Against Recurrent Stroke Study PWV : pulse wave velocity QALY : Quality adjusted life years RAA : renin-angiotensin-aldosterone RAS : renin-angiotensin system RCT : randomized controlled trials RF : risk factor ROADMAP : Randomized Olmesartan And Diabetes MicroAlbuminuria Prevention SBP : systolic blood pressure SCAST : Angiotensin-Receptor Blocker Candesartan for Treatment of Acute STroke SCOPE : Study on COgnition and Prognosis in the Elderly SCORE : Systematic COronary Risk Evaluation SHEP : Systolic Hypertension in the Elderly Program STOP : Swedish Trials in Old Patients with Hypertension STOP-2 : The second Swedish Trial in Old Patients with Hypertension SYSTCHINA : SYSTolic Hypertension in the Elderly: Chinese trial SYSTEUR : SYSTolic Hypertension in Europe TIA : transient ischaemic attack TOHP : Trials Of Hypertension Prevention TRANSCEND : Telmisartan Randomised AssessmeNt Study in ACE iNtolerant subjects with cardiovascular Disease UKPDS : United Kingdom Prospective Diabetes Study VADT : Veterans' Affairs Diabetes Trial VALUE : Valsartan Antihypertensive Long-term Use Evaluation WHO : World Health Organization ### 1.1 Principles The 2013 guidelines on hypertension of the European Society of Hypertension (ESH) and the European Society of Cardiology …

Diagnosis and Management of the Metabolic Syndrome An American Heart Association/National Heart, Lung, and Blood Institute Scientific Statement

Abstract: The metabolic syndrome has received increased attention in the past few years. This statement from the American Heart Association (AHA) and the National Heart, Lung, and Blood Institute (NHLBI) is intended to provide up-to-date guidance for professionals on the diagnosis and management of the metabolic syndrome in adults. The metabolic syndrome is a constellation of interrelated risk factors of metabolic origin— metabolic risk factors —that appear to directly promote the development of atherosclerotic cardiovascular disease (ASCVD).1 Patients with the metabolic syndrome also are at increased risk for developing type 2 diabetes mellitus. Another set of conditions, the underlying risk factors , give rise to the metabolic risk factors. In the past few years, several expert groups have attempted to set forth simple diagnostic criteria to be used in clinical practice to identify patients who manifest the multiple components of the metabolic syndrome. These criteria have varied somewhat in specific elements, but in general they include a combination of both underlying and metabolic risk factors. The most widely recognized of the metabolic risk factors are atherogenic dyslipidemia, elevated blood pressure, and elevated plasma glucose. Individuals with these characteristics commonly manifest a prothrombotic state and a pro-inflammatory state as well. Atherogenic dyslipidemia consists of an aggregation of lipoprotein abnormalities including elevated serum triglyceride and apolipoprotein B (apoB), increased small LDL particles, and a reduced level of HDL cholesterol (HDL-C). The metabolic syndrome is often referred to as if it were a discrete entity with a single cause. Available data suggest that it truly is a syndrome, ie, a grouping of ASCVD risk factors, but one that probably has more than one cause. Regardless of cause, the syndrome identifies individuals at an elevated risk for ASCVD. The magnitude of the increased risk can vary according to which components of the syndrome are …

2007 Guidelines for the Management of Arterial Hypertension : The Task Force for the Management of Arterial Hypertension of the European Society of Hypertension (ESH) and of the European Society of Cardiology (ESC).

Abstract: 2007 Guidelines for the Management of Arterial Hypertension : The Task Force for the Management of Arterial Hypertension of the European Society of Hypertension (ESH) and of the European Society of Cardiology (ESC).

2013 ESH/ESC Guidelines for the management of arterial hypertension: the Task Force for the management of arterial hypertension of the European Society of Hypertension (ESH) and of the European Society of Cardiology (ESC)

Abstract: Because of new evidence on several diagnostic and therapeutic aspects of hypertension, the present guidelines differ in many respects from the previous ones. Some of the most important differences are listed below: 1. Epidemiological data on hypertension and BP control in Europe. 2. Strengthening of the prognostic value of home blood pressure monitoring (HBPM) and of its role for diagnosis and management of hypertension, next to ambulatory blood pressure monitoring (ABPM). 3. Update of the prognostic significance of night-time BP, white-coat hypertension and masked hypertension. 4. Re-emphasis on integration of BP, cardiovascular (CV) risk factors, asymptomatic organ damage (OD) and clinical complications for total CV risk assessment. 5. Update of the prognostic significance of asymptomatic OD, including heart, blood vessels, kidney, eye and brain. 6. Reconsideration of the risk of overweight and target body mass index (BMI) in hypertension. 7. Hypertension in young people. 8. Initiation of antihypertensive treatment. More evidence-based criteria and no drug treatment of high normal BP. 9. Target BP for treatment. More evidence-based criteria and unified target systolic blood pressure (SBP) (<140 mmHg) in both higher and lower CV risk patients. 10. Liberal approach to initial monotherapy, without any all-ranking purpose. 11. Revised schema for priorital two-drug combinations. 12. New therapeutic algorithms for achieving target BP. 13. Extended section on therapeutic strategies in special conditions. 14. Revised recommendations on treatment of hypertension in the elderly. 15. Drug treatment of octogenarians. 16. Special attention to resistant hypertension and new treatment approaches. 17. Increased attention to OD-guided therapy. 18. New approaches to chronic management of hypertensive disease

Diagnosis and management of the metabolic syndrome: an American Heart Association/National Heart, Lung, and Blood Institute scientific statement.

Abstract: The metabolic syndrome has received increased attention in the past few years. This statement from the American Heart Association (AHA) and the National Heart, Lung, and Blood Institute (NHLBI) is intended to provide up-to-date guidance for professionals on the diagnosis and management of the metabolic syndrome in adults. The metabolic syndrome is a constellation of interrelated risk factors of metabolic origin— metabolic risk factors —that appear to directly promote the development of atherosclerotic cardiovascular disease (ASCVD).1 Patients with the metabolic syndrome also are at increased risk for developing type 2 diabetes mellitus. Another set of conditions, the underlying risk factors , give rise to the metabolic risk factors. In the past few years, several expert groups have attempted to set forth simple diagnostic criteria to be used in clinical practice to identify patients who manifest the multiple components of the metabolic syndrome. These criteria have varied somewhat in specific elements, but in general they include a combination of both underlying and metabolic risk factors. The most widely recognized of the metabolic risk factors are atherogenic dyslipidemia, elevated blood pressure, and elevated plasma glucose. Individuals with these characteristics commonly manifest a prothrombotic state and a pro-inflammatory state as well. Atherogenic dyslipidemia consists of an aggregation of lipoprotein abnormalities including elevated serum triglyceride and apolipoprotein B (apoB), increased small LDL particles, and a reduced level of HDL cholesterol (HDL-C). The metabolic syndrome is often referred to as if it were a discrete entity with a single cause. Available data suggest that it truly is a syndrome, ie, a grouping of ASCVD risk factors, but one that probably has more than one cause. Regardless of cause, the syndrome identifies individuals at an elevated risk for ASCVD. The magnitude of the increased risk can vary according to which components of the syndrome are …