Browsing by Author "Rayner, B L"

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    The abridged South African hypertension guideline 2011
    (South African Academy of Family Physicians, 2013) Seedat, Y K; Rayner, B L
    Extensive data from randomised controlled trials have shown the benefit of treating hypertension. The target blood pressure (BP) for antihypertensive management is < 140/90 mmHg, and < 130/80 mmHg in patients with end-organ damage, coexisting risk factors, and co-morbidity. Benefits of management include reduced risk of death, stroke, cardiac failure, chronic kidney disease, and coronary heart disease. The correct BP measurement procedure is described, and evaluation of cardiovascular risk factors and recommendations for antihypertensive therapy, are stipulated. Lifestyle modification and patient education are cornerstones in the management of every patient. Major indications, precautions, and contraindications to each recommended antihypertensive drug are listed. Combination therapy should be considered ab initio if the BP is ≥ 20/10 mmHg above goal. First-line drug therapy for uncomplicated essential hypertension includes low-dose thiazide-like diuretics, calcium-channel blockers, angiotensin-converting enzyme inhibitors, or angiotensin-receptor blockers. The guideline was developed by the Southern African Hypertension Society.
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    Hypertension, chronic kidney disease, atrial fibrillation and the newer anticoagulants
    (South African Academy of Family Physicians, 2012) Rayner, B L
    Atrial fibrillation (AF) is a common clinical condition that is associated with increased morbidity and mortality that mainly relates to an embolic stroke. Dominant risk factors for AF are advanced age and hypertension in the absence of mitral valve disease.1 In turn, hypertension and ageing are determinants of the congestive heart failure, hypertension, age, diabetes mellitus, prior stroke or transient ischaemic attack or thromboembolism (CHADS2) criteria for assessing the indication for anticoagulation. In addition, they are important risk factors for chronic kidney disease (CKD). In itself, CKD is an independent risk factor for AF and a higher risk of stroke.2 It is highly likely that a practitioner will encounter older patients with AF and concomitant hypertension and CKD that require anticoagulation therapy. Thus, it is essential for the practitioner to understand the risks and benefits of anticoagulation in older patients with AF, hypertension and CKD.
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    Metabolic syndrome, the leptin gene and kidney disease in non-diabetic black South Africans
    (2008) Okpechi, Ikechi Gareth; Meissner, P; Rayner, B L; Ramesar, R; Pascoe, M D
    Obesity is a worldwide problem and is a factor in the pathogenesis of the metabolic syndrome and kidney disease through the development of obesity-related hypertension and neurohormonal mechanisms that include the action of leptin. As there appear to be no focussed studies that have looked at the association of the LEP gene with kidney disease phenotypes or cardiovascular disease markers like hypertension, the metabolic syndrome and obesity, and especially so in native black Africans, this study sought to establish an association between the obesity gene (LEP) and kidney disease phenotypes (independent of diabetes and hypertension) in a homogenous black African population.
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    The R563Q mutation of the beta subunit of the epithelial sodium channel : prevalence and effect
    (2009) Jones, Erika Sherad Wilshire; Rayner, B L; Owen, E P; Meissner, P N
    Hypertension is a major worldwide predictor of morbidity and mortality. The search for genes that contribute to blood pressure is ongoing. The epithelial sodium channel genes were implicated when the beta subunit (SCNN1B, gene ID 6338) was found to have a mutation that caused Liddle’s syndrome. The R563Q mutation in the beta subunit has been associated with hypertension and pre-eclampsia in the Xhosa and Coloured people in Cape Town. The thesis consists of a cross-sectional analysis of the prevalence of the R563Q mutation in multiple ethnic groups in South Africa and a longitudinal functional assessment in response to saline infusion. The objectives were to determine the prevalence of the R563Q mutation and association with hypertension, and if it persists within families; to speculate as to the origins of the mutation; to determine if there were any relevant clinical differences between comparable patients with essential hypertension; to determine if the mutation predicted a difference in response to acute sodium loading and if a physiological difference is observed in sodium channel activity when expressed in oocytes. A high frequency of hypertensives in Johannesburg and Cape Town were found to be heterozygous and the mutation associated with hypertension, including within families. In the Khoisan the R563Q mutation was found at a high frequency (19%) in a random sample, suggesting the mutation originated from this population. The saline challenge illustrated the in vivo effects of the mutation. The results suggest that the sodium channel is innately overactive in heterozygous subjects and that counter-regulatory mechanisms are in place to compensate for changes in renal sodium handling. However, preliminary in vitro testing in oocytes did not show a difference in sodium channel activity.
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    The R563Q Mutation of the Beta Subunit of the Epithelial Sodium Channel: Prevalence and Effect
    (2009) Jones, Dr Erika Sherad Wilshire; Rayner, B L; Owen, E P; Meissner, P N
    Hypertension is a major worldwide predictor of morbidity and mortality. The search for genes that contribute to blood pressure is ongoing. The epithelial sodium channel genes were implicated when the beta subunit (SCNN1B, gene ID 6338) was found to have a mutation that caused Liddle's syndrome. The R563Q mutation in the beta subunit has been associated with hypertension and pre-eclampsia in the Xhosa and Coloured people in Cape Town. The thesis consists of a cross-sectional analysis of the prevalence of the R563Q mutation in multiple ethnic groups in South Africa and a longitudinal functional assessment in response to saline infusion. The objectives were to determine the prevalence of the R563Q mutation and association with hypertension, and if it persists within families; to speculate as to the origins of the mutation; to determine if there were any relevant clinical differences between comparable patients with essential hypertension; to determine if the mutation predicted a difference in response to acute sodium loading and if a physiological difference is observed in sodium channel activity when expressed in oocytes. 8 A high frequency of hypertensives in Johannesburg and Cape Town were found to be heterozygous and the mutation associated with hypertension, including within families. In the Khoisan the R563Q mutation was found at a high frequency (19%) in a random sample, suggesting the mutation originated from this population. The saline challenge illustrated the in vivo effects of the mutation. The results suggest that the sodium channel is innately overactive in heterozygous subjects and that counter-regulatory mechanisms are in place to compensate for changes in renal sodium handling. However, preliminary in vitro testing in oocytes did not show a difference in sodium channel activity. Conclusion: This thesis has shown that the R563Q mutation is found in multiple ethnic groups in South Africa, in which it associates with hypertension; and possibly originated from the Khoisan. In vivo effects are described. The results are important because hypertension resulting from the R563Q mutation is a common and treatable cause of hypertension. It is recommended that hypertension units in South Africa screen for the mutation and alter treatment appropriately. A further recommendation is that a sodium channel inhibitor, such as amiloride, in an appropriate form, is registered in South Africa for the treatment of hypertension.
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    South African Hypertension Guideline 2006
    (2006) Seedat, Y K; Croasdale, M A; Milne, F J; Opie, L H; Pinkney-Atkinson, VJ; Rayner, B L; Veriava Y
    Outcomes. Extensive data from many randomised controlled trials have shown the benefit of treating hypertension. The target blood pressure (BP) for antihypertensive management should be systolic BP < 140 mmHg, diastolic BP < 90 mmHg, with minimal or no drug side-effects. However, a lesser reduction will elicit benefit although this is not optimal. The reduction of BP in the elderly should generally be achieved gradually over 6 months. Stricter BP control is required for patients with end-organ damage, co-existing risk factors and co-morbidity, e.g. diabetes mellitus. Co-existent risk factors should also be controlled. Benefits. Reduction in risk of stroke, cardiac failure, renal insufficiency and coronary artery disease. The major precautions and contraindications to each antihypertensive drug recommended are listed. Recommendations. Correct BP measurement procedure is described. Evaluation of cardiovascular risk factors and recommendations for antihypertensive therapy are stipulated. The total cardiovascular disease risk profile should be determined for all patients and this should inform management strategies. Lifestyle modification and patient education are cornerstones in the management of every patient. Drug therapy for the patient with uncomplicated hypertension should be as follows: first line – low-dose thiazide or thiazide-like diuretics; second line – add either an angiotensin-converting enzyme inhibitor (ACE-I) or a calcium channel blocker (CCB); third line – add another second-line drug not already used. In resistant hypertension where a fourth drug is needed, use either a centrally acting drug, vasodilator, alpha-blocker, or beta-blocker. The order of drug choice may change in those with compelling indications for a particular drug class. The guideline includes management of specific situations including hypertensive emergency and urgency, severe hypertension with target-organ damage and hypertension in diabetes mellitus, etc. Validity. The guideline was developed by a joint Southern African Hypertension Society and National Department of Health Directorate: Chronic Diseases, Disabilities and Geriatrics working group. Input was also obtained from representatives of the various related professional societies.