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8 result(s) for "Freel, E. Marie"
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ACTH and Polymorphisms at Steroidogenic Loci as Determinants of Aldosterone Secretion and Blood Pressure
The majority of genes contributing to the heritable component of blood pressure remain unidentified, but there is substantial evidence to suggest that common polymorphisms at loci involved in the biosynthesis of the corticosteroids aldosterone and cortisol are important. This view is supported by data from genome-wide association studies that consistently link the CYP17A1 locus to blood pressure. In this review article, we describe common polymorphisms at three steroidogenic loci (CYP11B2, CYP11B1 and CYP17A1) that alter gene transcription efficiency and levels of key steroids, including aldosterone. However, the mechanism by which this occurs remains unclear. While the renin angiotensin system is rightly regarded as the major driver of aldosterone secretion, there is increasing evidence that the contribution of corticotropin (ACTH) is also significant. In light of this, we propose that the differential response of variant CYP11B2, CYP11B1 and CYP17A1 genes to ACTH is an important determinant of blood pressure, tending to predispose individuals with an unfavourable genotype to hypertension.
Central mineralocorticoid receptors, sympathetic activity, and hypertension
Recent evidence highlighting the presence of corticosteroid receptors in the central nervous system has prompted further investigation regarding their role in the pathogenesis of hypertension. The sympathetic nervous system, an important factor in the pathogenesis of hypertension, is influenced by sodium and volume status. Activation of central nervous system mineralocorticoid receptors is known to affect sympathetic activity, although the processes that underpin this phenomenon are incompletely understood. This article reviews some of the recent advances in this area, particularly mechanisms by which the mineralocorticoid receptor maintains selectivity for its ligand within the central nervous system, its role in salt appetite, and the possibility of local production of corticosteroids. In addition, the links between central mineralocorticoid receptor activation, stress, sympathetic activity, and hypertension are discussed.
Disorders of Blood Pressure Regulation—Role of Catecholamine Biosynthesis, Release, and Metabolism
Catecholamines (epinephrine and norepinephrine) are synthesised and produced by the adrenal medulla and postganglionic nerve fibres of the sympathetic nervous system. It is known that essential hypertension has a significant neurogenic component, with the rise in blood pressure mediated at least in part by overactivity of the sympathetic nervous system. Moreover, novel therapeutic strategies aimed at reducing sympathetic activity show promise in the treatment of hypertension. This article reviews recent advances within this rapidly changing field, particularly focusing on the role of genetic polymorphisms within key catecholamine biosynthetic enzymes, cofactors, and storage molecules. In addition, mechanisms linking the sympathetic nervous system and other adverse cardiovascular states (obesity, insulin resistance, dyslipidaemia) are discussed, along with speculation as to how recent scientific advances may lead to the emergence of novel antihypertensive treatments.
Management of hypertensive emergencies and urgencies: narrative review
Hypertensive emergencies are distinguished from hypertensive urgencies by the presence of clinical or laboratory target organ damage. The most common forms of target organ damage in developed countries are pulmonary oedema/heart failure, acute coronary syndrome, ischaemic and haemorrhagic stroke. In the absence of randomised trials, it is inevitable that guideline writers differ slightly regarding the speed and extent to which blood pressure should be lowered acutely. An appreciation of cerebral autoregulation is key and should underpin treatment decisions. Hypertensive emergencies, with the notable exception of uncomplicated malignant hypertension, require intravenous antihypertensive medication which is most safely given in high dependency or intensive care settings. Patients with hypertensive urgency are often treated with medications that lower their blood pressure acutely, although there is no evidence to support this practice. This article aims to review current guidelines and recommendations, and to provide user friendly management strategies for the general physician.
Diagnosis of adenomatous primary aldosteronism in a patient with severe hypertension
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.
Aldosterone status associated with insulin resistance in patients with heart failure—data from the ALOFT study
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.
Primary aldosteronism: an update
Primary aldosteronism (PA) is common with an estimated prevalence rate of 10% in subjects with essential hypertension and higher in those with resistant hypertension. As well as contributing to hypertension, aldosterone has detrimental effects on the heart, vasculature and kidneys as well as adverse metabolic effects leading to an excess of cardiovascular morbidity. Therefore, recognition and appropriate treatment of PA is of increasing importance. However, the diagnosis of PA and determination of subtype can be problematic. The purpose of this review is to provide an overview of the evidence supporting this increased prevalence of PA, explore the metabolic and cardiovascular consequences of aldosterone excess and discuss optimal diagnostic and therapeutic strategies of PA.
Outcomes of Patients with Nelson’s Syndrome after Primary Treatment: A Multicenter Study from 13 UK Pituitary Centers
Long-term outcomes of patients with Nelson's syndrome (NS) have been poorly explored, especially in the modern era. To elucidate tumor control rates, effectiveness of various treatments, and markers of prognostic relevance in patients with NS. Retrospective cohort study of 68 patients from 13 UK pituitary centers with median imaging follow-up of 13 years (range 1-45) since NS diagnosis. Management of Cushing's disease (CD) prior to NS diagnosis included surgery+adrenalectomy (n = 30; eight patients had 2 and one had 3 pituitary operations), surgery+radiotherapy+adrenalectomy (n = 17; two received >1 courses of irradiation, two had ≥2 pituitary surgeries), radiotherapy+adrenalectomy (n = 2), and adrenalectomy (n = 19). Primary management of NS mainly included surgery, radiotherapy, surgery+radiotherapy, and observation; 10-year tumor progression-free survival was 62% (surgery 80%, radiotherapy 52%, surgery+radiotherapy 81%, observation 51%). Sex, age at CD or NS diagnosis, size of adenoma (micro-/macroadenoma) at CD diagnosis, presence of pituitary tumor on imaging prior adrenalectomy, and mode of NS primary management were not predictors of tumor progression. Mode of management of CD before NS diagnosis was a significant factor predicting progression, with the group treated by surgery+radiotherapy+adrenalectomy for their CD showing the highest risk (hazard ratio 4.6; 95% confidence interval, 1.6-13.5). During follow-up, 3% of patients had malignant transformation with spinal metastases and 4% died of aggressively enlarging tumor. At 10 years follow-up, 38% of the patients diagnosed with NS showed progression of their corticotroph tumor. Complexity of treatments for the CD prior to NS diagnosis, possibly reflecting corticotroph adenoma aggressiveness, predicts long-term tumor prognosis.