ORCID Profile
0000-0002-3051-2707
Current Organisation
North-West University
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Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 08-2021
DOI: 10.1161/HYPERTENSIONAHA.120.16879
Abstract: This study presents a detailed profile of the renin-angiotensin-aldosterone system (RAAS), electrolytes, volume loading, blood pressure (BP), and total peripheral resistance in healthy young Black and White adults. We also explored longitudinal associations between BP and RAAS. We included normotensive Black (N=543) and White (N=573) adults (20–30 years) and followed N=324 over ≈4.5 years. We measured clinic (central, brachial) and 24-hour BP, total peripheral resistance and left ventricular dimensions. We determined serum NT-proBNP (N-terminal prohormone B-type natriuretic peptide), RAAS, and 24-hour urinary and serum Na + and K + . RAAS components, left ventricular internal diameter (diastole), end diastolic volume and NT-proBNP were lower ( P .001) in Black than White adults, despite similar clinic SBP. However, central systolic BP and total peripheral resistance were higher in Black adults ( P .001). Plasma renin activity and angiotensin II were comparable between Black and White groups ( P .05) only in quartile 1 of Na + /K + values. In both groups, RAAS was lower in the higher quartiles of 24-hour Na + and NT-proBNP (all P -trend≤0.014). Over 4.5 years, all BPs increased in the Black ( P .001) but not White group. The increase in central systolic BP over time was associated with elevated serum aldosterone only in Black adults (β=0.18, P =0.038). We found that RAAS concentrations in healthy Black adults were half of those of White participants, which may not be explained by volume expansion. Yet, baseline aldosterone predicted BP elevation over time in Black adults. RAAS was similar in Black and White adults only at low Na + /K + scenarios, suggesting an essential role of potassium. URL: www.clinicaltrials.gov Unique identifier: NCT03292094.
Publisher: Springer Science and Business Media LLC
Date: 25-06-2021
DOI: 10.1038/S41371-021-00569-6
Abstract: Exogenous estrogens and progestins may affect the components of the renin-angiotensin-aldosterone system (RAAS). Changes in ventricular blood volume are associated with increased secretion of N-terminal pro-hormone B-type natriuretic peptide (NT-proBNP), which may also be affected by hormonal contraceptives. In this study, we aimed to compare components of the RAAS and NT-proBNP between groups using different hormonal contraceptives, including the combination pill, the injection or implant, and controls (no contraception) in black and white women of fertile age (20 - 30 years). Secondly, we determined whether blood pressure and NT-proBNP are associated with the RAAS components. We included 397 black and white women not using contraceptives, 120 using the combination pill, and 103 receiving an injection/implant. RAAS Triple-A analysis was carried out with LC-MS/MS quantification, and blood pressure measurements (ABPM) taken over 24 h. We found that serum aldosterone was higher (475.7 vs. 249.2 pmol/L p < 0.001) in the combination pill group than in the no contraception group of white women. The aldosterone-angiotensin II ratio (AA2) was higher (5.4 vs. 2.5 p < 0.001) in the combination pill group than in the no contraception group. In the black women using the combination pill, we found a borderline-positive and borderline-negative association between 24-h systolic blood pressure and NT-proBNP with equilibrium (eq) Ang II, respectively. In white women using the combination pill, only CRP contributed positively and independently to NT-proBNP. To conclude, activation of RAAS by different hormonal contraceptives may increase future risk for the development of hypertension in young black and white women.
Publisher: Elsevier BV
Date: 08-2014
DOI: 10.1016/J.NUMECD.2014.02.005
Abstract: Simple, low-cost central obesity measures may help identify in iduals with increased cardiometabolic disease risk, although it is unclear which measures perform best in African adults. We aimed to: 1) cross-sectionally compare the accuracy of existing waist-to-height ratio (WHtR) and waist circumference (WC) thresholds to identify in iduals with hypertension, pre-diabetes, or dyslipidaemia 2) identify optimal WC and WHtR thresholds to detect CVD risk in this African population and 3) assess which measure best predicts 5-year CVD risk. Black South Africans (577 men, 942 women, aged >30years) were recruited by random household selection from four North West Province communities. Demographic and anthropometric measures were taken. Recommended diagnostic thresholds (WC > 80 cm for women, >94 cm for men WHtR > 0.5) were evaluated to predict blood pressure, fasting blood glucose, lipids, and glycated haemoglobin measured at baseline and 5 year follow up. Women were significantly more overweight than men at baseline (mean body mass index (BMI) women 27.3 ± 7.4 kg/m(2), men 20.9 ± 4.3 kg/m(2)) median WC women 81.9 cm (interquartile range 61-103), men 74.7 cm (63-87 cm), all P 0.5 appears to be more consistently supported and may provide a better predictor of future cardiometabolic risk in sub-Saharan Africa.
Publisher: Elsevier BV
Date: 04-2013
DOI: 10.1016/J.ATHEROSCLEROSIS.2013.01.001
Abstract: Defensive coping (AC) responses in urban African males have been associated with vascular responsiveness, partly explaining autonomic nervous system dysfunction. We therefore aimed to assess whether AC responses facilitate higher blood pressure and early sub-clinical structural vascular disease via alterations in frequency- and time-domain heart rate variability (HRV) responses. We included 355 African and Caucasian men and women without pre-existing atrial fibrillation, aged 45 ± 9 years. Significant interaction on main effects (coping × ethnicity × gender) for left carotid intima media thickness far wall (L-CIMTf) and cross sectional wall area values necessitated selection of AC responders above mean via the Coping Strategy Indicator. We collected B-mode ultrasound L-CIMTf, ambulatory BP and-HRV data. Overnight fasting blood was obtained. Overall, Africans and AC Africans, mostly men, revealed a poorer lifestyle profile, higher prevalence of hypertensive status, disturbed sympathovagal balance and depressed HRV temporal and geometric patterns compared to the Caucasians (P ≤ 0.05). Moderately depressed non-linear and time-domain HRV (SDNN <100 ms) was prevalent in 28% of Africans compared to 11% of Caucasians. A similar trend was shown for the AC African participants (32%) compared to Caucasians (16%). Only depressed HRV time-domain (SDNN: adj. R(2) = 0.34 β = -0.24 p = 0.08) and vagal-impaired heart rate responses (RMSSD: adj. R(2) = 0.28 β = -0.28 p < 0.05) were associated with higher blood pressure and early structural vascular changes in AC African men. Defensive coping facilitated autonomic nervous system dysfunction, which was associated with higher blood pressure and sub-clinical structural vascular disease in an African male cohort.
Publisher: Elsevier BV
Date: 02-2019
Publisher: Oxford University Press (OUP)
Date: 06-01-2019
Abstract: Globally hypertension is stabilising, but in sub-Saharan Africa the incidence of hypertension remains on an increase. Although this might be attributed to poor healthcare and ineffective antihypertensive treatment, there is a limited understanding of population and in idual-specific cardiovascular pathophysiology – necessary for effective prevention and treatment strategies in Africa. As there is a lack of longitudinal studies tracking the early pathophysiological development of hypertension in black populations, the African-PREDICT study was initiated. The purpose of this paper is to describe the detailed methodology and baseline cohort profile of the study. From 2013 to 2017, the study included 1202 black ( N = 606) and white ( N = 596) men and women (aged 20–30 years) from South Africa – screened to be healthy and clinic normotensive. At baseline, and each 5-year follow-up examination, detailed measures of health behaviours, cardiovascular profile and organ damage are taken. Also, comprehensive biological s ling for the ‘omics’ and biomarkers is performed. Overall, the baseline black and white cohort presented with similar ages, clinic and 24-hour blood pressures, but black adults had lower socioeconomic status and higher central systolic blood pressure than white in iduals. The prospective African-PREDICT study in young black and white adults will contribute to a clear understanding of early cardiovascular disease development.
No related grants have been discovered for Lisa Uys.