Sympathetic Activity And Ambulatory Blood Pressure In Africans Research Articles

Associations of conscientiousness with cardiac troponin T and stress coping responses in a teacher cohort: the SABPA prospective cohort study.

In a South African bi-ethnic cohort, defensive (DefS)/social support/avoidance coping strategies have been shown to influence cardiac troponin T (cTnT) levels through different stress signalling pathways. Personality traits (extraversion, neuroticism, conscientiousness, openness to experience, agreeableness) partially control stress coping responses and may affect prospective cardiac responses. Hence in this cohort, we aimed to examine relationships between personality traits and coping strategies, and to assess associations between cTnT changes over time, personality traits and coping strategies. A cohort of African and Caucasian male and female teachers (n = 359) participating in both phases of the Sympathetic activity and Ambulatory Blood Pressure in Africans (SABPA) study, was prospectively followed for three years. Personality traits (Basic Traits Inventory) and coping (Coping Strategy Indicator) scores were determined. Fasting serum samples for cTnT determination were collected. Established hypertension-related cTnT cut-off points of 4.2 pg/ml (Africans) and 5.6 pg/ml (Caucasians) were applied. Higher neuroticism and lower conscientiousness scores were found in the Africans than in the Caucasians (p < 0.05). Both traits correlated with all three coping strategies in Caucasians, but only with DefS and avoidance coping in Africans. Over a period of three years, cTnT levels decreased in both races. Compared to Africans, Caucasians showed a greater recovery from the ethnic-specific cTnT cut-off point over time. In the Africans with high DefS scores, cTnT level changes were inversely associated with conscientiousness (adjusted R2 = 0.14; β = -0.26). In Caucasians scoring high in avoidance coping, conscientiousness (odds ratio 0.84) and neuroticism (odds ratio 0.90) showed a lower likelihood of predicting the cTnT cut-off point. In both races, conscientiousness may contribute to healthier stress coping responses and protect against cardiac ischaemia and risk of hypertension.

The relationship between physical activity, body fatness and metabolic syndrome in urban South African school teachers: The sympathetic activity and ambulatory blood pressure in Africans study.

BackgroundGlobally, the prevalence of metabolic syndrome (MS) is rising because of increased levels of physical inactivity and obesity. In South Africa, information about teachers’ physical activity (PA), body fatness and MS is limited.AimTo assess the relationship between PA, body fatness and MS in urban South African teachers.SettingThe study setting was in Dr Kenneth Kaunda District in the North West province of South Africa.MethodsA cross-sectional study was conducted using secondary data drawn from the sympathetic activity and ambulatory blood pressure in Africans (SABPA) study of 216 teachers (aged 25–65 years). Variables included anthropometry, biochemical measurements, objectively measured PA and lifestyle behaviours.ResultsTwenty-nine percent of the total participants were classified with MS, with 46% in men compared to 13% in women; 33% were sedentary and 67% participated in light activity. A weak significant negative relationship was found between the mean 7-day awake metabolic equivalent of tasks (METs) and triglycerides (r = −0.29; p = 0.02) and gamma-glutamyl transferase (r = −0.25; p = 0.06), activity energy expenditure (r = −0.24; p = 0.06) and PA level (r = −0.23; p = 0.07). After adjusting for age, self-reported smoking and alcohol use or consumption, a weak significant negative relationship between mean 7-day awake METs and triglycerides (r = −0.28; p < 0.01) was observed.ConclusionIn the teachers with MS, only one MS marker (triglycerides) showed a negative association with PA. Physical activity could therefore be beneficial in the regulation of triglycerides. Participation in regular PA could be beneficial in the regulation of triglycerides. Focused PA interventions in school teachers that advocate the benefits of PA and healthy lifestyle choices to reduce dietary fat intake (and alcohol) are recommended.

Exploring biomarkers associated with deteriorating vascular health using a targeted proteomics chip: The SABPA study.

In this observational study, by the use of a multiplex proteomic platform, we aimed to explore associations between 92 targeted proteins involved in cardiovascular disease and/or inflammation, and phenotypes of deteriorating vascular health, with regards to ethnicity.Proteomic profiling (92 proteins) was carried out in 362 participants from the Sympathetic activity and Ambulatory Blood Pressure in Africans (SABPA) study of black and white African school teachers (mean age 44.7 ± 9.9 years, 51.9% women, 44.5% Black Africans, 9.9% with known cardiovascular disease). Three proteins with <15% of samples below detectable limits were excluded from analyses. Associations between multiple proteins and prevalence of hypertension as well as vascular health [Carotid intima-media thickness (cIMT) and pulse wave velocity (PWV)] measures were explored using Bonferroni-corrected regression models.Bonferroni-corrected significant associations between 89 proteins and vascular health markers were further adjusted for clinically relevant co-variates. Hypertension was associated with growth differentiation factor 15 (GDF-15) and C-X-C motif chemokine 16 (CXCL16). cIMT was associated with carboxypeptidase A1 (CPA1), C-C motif chemokine 15 (CCL15), chitinase-3-like protein 1 (CHI3L1), scavenger receptor cysteine-rich type 1 protein M130 (CD163) and osteoprotegerin, whereas PWV was associated with GDF15, E-selectin, CPA1, fatty acid-binding protein 4 (FABP4), CXCL16, carboxypeptidase B (CPB1), and tissue-type plasminogen activator. Upon entering ethnicity into the models, the associations between PWV and CPA1, CPB1, GDF-15, FABP4, CXCL16, and between cIMT and CCL-15, remained significant.Using a multiplex proteomic approach, we linked phenotypes of vascular health with several proteins. Novel associations were found between hypertension, PWV or cIMT and proteins linked to inflammatory response, chemotaxis, coagulation or proteolysis. Further, we could reveal whether the associations were ethnicity-dependent or not.

Relationship between physical activity and carotid intima–media thickness among teachers in South Africa: the SABPA study

To determine the relationship between objectively measured physical activity (PA) and carotid intima-media thickness (CIMT) in teachers in South Africa. A cross-sectional study was conducted among 215 teachers aged 25 to 65 years (mean age 49.67 ± 8.43 years) who participated in the Sympathetic Activity and Ambulatory Blood Pressure in Africans (SABPA) prospective cohort study. CIMT was measured using the SonoSite Micromaxx ultrasound over seven consecutive days. Other measurements obtained included body mass index (BMI), waist circumference, 24-hour ambulatory blood pressure, and C-reactive protein (CRP) and fasting blood total cholesterol levels. Data were analysed using Statistical Package for Social Sciences (SPSS) version 25. The prevalence of obesity according to BMI and sedentary behaviour was above 30%; hypertension was 38.9% and CRP 41.1 mg/dl. Male teachers showed higher mean values for CIMT than female teachers (0.75 ± 0.16 vs 0.66 ± 0.12 mm; p ≤ 0.05). A borderline negative association existed between CIMT and mean seven-day awake metabolic equivalent of task (r = -0.19; p = 0.08) in female teachers in the light-PA group. CIMT was inversely associated with total energy expenditure (r = -0.31; p = 0.05) in sedentary male teachers. Participation in light PA was associated with lower CIMT values in female teachers. Given the health implications of cardiovascular disease risk among teachers, PA intervention studies are recommended to determine effective interventions to provide information on how to decrease the progression of subclinical atherosclerosis in this population.

Ambulatory blood pressure monitoring and morning surge in blood pressure in adult black and white South Africans.

We examined whether there were differences in the circadian variation in blood pressure and the morning surge in blood pressure between black and white Africans. Clinic and ambulatory blood pressure data obtained from the Sympathetic Activity and Ambulatory Blood Pressure in Africans (SABPA) study was examined (n=406; 49% black African). Ambulatory blood pressure readings were fitted to a six-parameter double logistic equation to determine the power and rate of the morning surge in blood pressure. Multiple linear regression analysis was used to examine differences in blood pressure between black and white participants. Clinic and ambulatory blood pressure were higher in black participants throughout the day and night. In those taking medications, blood pressure was less well controlled in black subjects. Despite the higher systolic blood pressure, the day-night difference estimated by the logistic function was similar in black and white participants. However, the rate of rise and power in the morning surge in blood pressure was lower in black participants. We conclude that black participants of the SABPA study present with higher blood pressure throughout the day and night but have a lower power of the morning surge in blood pressure due to a slower morning rate of increase. Moreover, they had an increased prevalence of undiagnosed hypertension and, in those taking medication, were less likely to have their blood pressure controlled than their white counterparts.

3044Exploration of biomarkers for subclinical atherosclerosis in an African population using a proteomics chip targeted at inflammation and cardiovascular disease

Abstract Introduction The evolving use of multiplex proteomic platforms provides an excellent tool for investigating associations between multiple proteins and subclinical atherosclerotic disease. In this study, we evaluated the impact of a multiplex protein panel, on carotid intima-media thickness (cIMT) as a marker of subclinical atherosclerosis. Purpose We used a multiplex proteomic platform to identify possible associations between proteins and subclinical carotid atherosclerosis as measured by carotid ultrasound in an African population. Methods In the Sympathetic Activity and Ambulatory Blood Pressure in Africans (SABPA) study, 92 proteins from the Proseek Multiplex CVD III 96×96 (Olink Bioscience, Sweden) were analyzed in 378 participants (mean age 44.7±9.6 years, 50.6% women, 10.8% with known cardiovascular disease). Carotid ultrasound was performed for measurements of the carotid intima-media thickness (cIMT, mean 0.663±0.127 mm) and calculation of cross-sectional wall area (CSWA, mean 13.5±4.4mm2), a measure of target organ damage. Possible associations between the proteins, and cIMT and CSWA, respectively, were explored using linear regression models. A two-sided Bonferroni corrected P-value of 0.05/92=5.4x10–4 was considered statistically significant in the crude analysis. Results Of 18 proteins (1 standard deviation of change of ln-transformed values) that were Bonferroni-corrected (p≤5.4x10–4) significantly associated with cIMT and/or CWAS in crude analyses, the following remained significant after further adjustment for age, sex, waist circumference, systolic blood pressure, smoking and total cholesterol: growth-differentiation factor-15 (GDF15; β 0.017, p=0.050), E-selectin (SELE; β 0.019, p=0.017), carboxypeptidase A1 (CPA1; β 0.019, p=0.019), C-C motif chemokine 15 (CCL15; β 0.031, p&lt;0.001), chitinase-3-like protein 1 (CHI3L1; β 0.021, p=0.007), the hemoglobin scavenger receptor (CD163; β 0.021, p=0.008) and osteoprotegerin (OPG; β 0.022, p=0.004). As for target-organ damage defined by CSWA, SELE (β 0.459, p=0.018), CCL15 (β 0.398; p=0.032) and CD163 (β 0.541, p=0.005) showed multivariate adjusted significant associations. Conclusion In an African population, we could confirm five proteins (GDF15, SELE, CHI3L1, CD163 and OPG) associated with cIMT, but in addition identified two proteins (CPA1 and CCL15) with novel associations with cIMT and/or CSWA. Acknowledgement/Funding North-West University; National Research Foundation (NRF); Medical Research Council (MRC-SA); Department of Education North-West Province; ROCHE

Ethnicity-Specific Changes in Cardiac Troponin T in Response to Acute Mental Stress and Ethnicity-Specific Cutpoints for the R Wave of the aVL Lead.

Acute mental stressor-induced cardiac stress responses might contribute to excessive myocardial strain and resultant cardiovascular episode risk. We assessed ethnicity-specific acute cardiac stress (by measuring cardiac troponin T (cTnT) and N-terminal prohormone of brain natriuretic peptide) related to hemodynamic activity. The prospective Sympathetic Activity and Ambulatory Blood Pressure in Africans (SABPA) study was conducted during 2007-2008 in South Africa. In the cross-sectional phase of the SABPA study, 388 black and white participants underwent a 1-minute acute mental stressor, during which blood pressure was continuously measured. Fasting blood samples for cardiac stress markers were obtained before and 10 minutes after stress (% change). Resting 10-lead electrocardiogram measured the R wave of the aVL lead (RaVL). Black participants exhibited greater cardiac stress responses (P < 0.001), diastolic blood pressure, total peripheral resistance, and stroke volume compared with white participants, who displayed decreases in cardiac stress and increases in cardiac output. Prestress and stressor cTnT cutpoints of 4.2 pg/mL predicted 24-hour, daytime, and nighttime diastolic hypertension in black participants (P < 0.001). These cTnT cutpoints were associated with an ethnicity-specific RaVL cutpoint of 0.28 mV (odds ratio = 3.49, 95% confidence interval: 2.18, 5.83; P = 0.021). Acute mental stress elicited an α-adrenergic activation pattern and cardiac stress hyperreactivity only in black participants. Mental stress might increase the black population's risk for ischemic episodes and heart disease.

Implementing a new variant load model to investigate the role of mtDNA in oxidative stress and inflammation in a bi-ethnic cohort: the SABPA study

Mitochondrial DNA (mtDNA) variation has been implicated in several common complex and degenerative diseases, including cardiovascular disease. Inflammation is seen as part of many of these conditions. Mitochondria feature in inflammatory pathways and it has been suggested that mtDNA variation or released mtDNA might be important in this phenomenon. To determine if mtDNA is involved in the mechanisms leading up to cardiovascular disease, we investigated the role of these variants in seven indicators of oxidative stress and inflammation. This study was done in participants of the Sympathetic Activity and Ambulatory Blood Pressure in Africans (SABPA) cohort, a South African bi-ethnic cohort (N = 363). We applied a variant load hypothesis, which is an alternative approach to, and moves away from the classic haplogroup association approaches, to evaluate the cumulative effect of non-synonymous mtDNA variants on measurements of serum peroxides, nitric oxide metabolites, 8-hydroxy-deoxyguanosine, thiobarbituric acid reactive substances, whole blood reduced glutathione, C-reactive protein, and tumor necrosis factor alpha. We found no significant relationships between non-synonymous mtDNA variants and the seven biochemical parameters investigated here. Non-synonymous mtDNA variants are unlikely to impact on disease in this cohort, to an appreciable or measurable extent.

Retinal Vasculature Reactivity During Flicker Light Provocation, Cardiac Stress and Stroke Risk in Africans: The SABPA Study.

Structural and functional similarities exist between the retinal, cerebral and, as previously suggested, the coronary microvasculature. Retinal microvascular structure and functionality (in response to flicker-light-induced-provocation (FLIP)) may relate to coronary artery disease risk and possible stroke risk. We investigated associations between retinal vessel structure, functionality and cardiac stress markers (cardiac troponin T [cTnT], amino-terminal B-type natriuretic peptide [NT-proBNP]) to translate these retina-heart relationships to stroke risk. We included 317 African and Caucasian teachers' (aged 23-68years), who participated in the Sympathetic Activity and Ambulatory Blood Pressure in Africans (SABPA) study. Fasting plasma and serum samples for cTnT and NT-proBNP were collected. Retinal vascular calibres were quantified from fundus images and dynamic retinal vessel calibre responses during FLIP. The University of California stroke risk score was applied to assess sub-clinical 10-year stroke risk. cTnT levels were similar in Africans and Caucasians, whereas NT-proBNP levels were lower in Africans. In Africans, a reduced arteriolar calibre and attenuated arteriolar dilation during FLIP was associated with higher cTnT (p < 0.01). Their larger retinal-venular calibre (p < 0.02) and attenuated arteriolar dilation during FLIP (p < 0.05) were associated with lower NT-proBNP. Again, exclusively in Africans, increased cardiac stress, wider venular calibres and retinal arteriovenous nicking predicted an increased 10-year stroke risk with odds ratios of 1.57 (95% CI, 1.34; 1.68, p = 0.031), 1.51 (95% CI, 1.26; 1.59, p = 0.002), 1.10 (95% CI, 0.94; 2.85, p = 0.002) and 1.06 (95% CI 0.83; 1.56, p = 0.052), respectively. None of these associations were evident in the Caucasian group. Investigating the retinal vasculature may serve as a tool to approximate sub-clinical coronary and cerebral microvasculature damage or dysfunction. These cardiac stress-retinal associations additionally predicted a greater stroke risk in the SABPA African cohort. Observable changes in the retinal vasculature may serve as markers for the identification and prediction of cardio-systemic and cerebral vascular morbidities and risks, thereby establishing a brain-heart link. Graphical Abstract Proposed series of events during which sustained high pressure and increased cardiac stress may alter retinal reactivity and link to increased stroke risk.

Defensive coping and essential amino acid markers as possible predictors for structural vascular disease in an African and Caucasian male cohort: The SABPA study.

Defensive coping (DefS), oxidative stress, inflammation, and related amino acids (phenylalanine [Phe] and tyrosine [Tyr]) have been implicated in cardiovascular disease. This study assessed whether inflammation, oxidative stress, changes in essential amino acids, and altered coping strategies are correlated with subclinical vascular changes in African (n = 82) and Caucasian (n = 100) men from the Sympathetic Activity and Ambulatory Blood Pressure in Africans (SABPA) study. The Coping Strategy Indicator questionnaire identified DefS participants. Ambulatory blood pressure (BP) was monitored for 24 h, whereas carotid intima media thickness (CIMT) and cross-sectional wall area (CSWA) were determined ultrasonically. Essential amino acids were analyzed with a liquid chromatography tandem mass spectrometry method. Oxidative-inflammatory markers were measured by spectrophotometry. African men had poorer health than Caucasian men, including higher alcohol abuse, elevated BP, abdominal obesity, physical inactivity, and elevated inflammation. Phe (p < .001) and Phe/Tyr ratio (p = .006) as well as CIMT (p = .032) were higher in African men. DefS African men had higher levels of Phe (p = .002) and Phe/Tyr (p = .009) compared to DefS Caucasian men; these differences were not observed in non-DefS men. Systolic BP and inflammation (C-reactive protein) were positively associated with left (L-) CSWA, while Phe/Tyr was negatively associated with L-CSWA in DefS African men. African males presented with elevated Phe and Phe/Tyr ratio, catecholamine precursors, worsening during DefS-possibly driven by inflammation and BP contributing to structural vascular abnormalities.

Low serum testosterone and increased diastolic ocular perfusion pressure: a risk for retinal microvasculature.

Low levels of testosterone in men and changes in retinal microvascular calibre are both associated with hypertension and cardiovascular disease risk. Sex hormones are also associated with blood flow in microvascular beds which might be a key intermediate mechanism in the development of hypertension. Whether a direct association between endogenous testosterone and retinal microvascular calibre exists is currently unknown. We aimed to determine whether testosterone is independently associated with ocular perfusion via a possible association with retinal vascular calibre or whether it plays only a secondary role via its effect on blood pressure in a bi-ethnic male cohort. A total of 72 black and 81 white men (28-68 years of age) from the follow-up phase of the Sympathetic activity and Ambulatory Blood Pressure in Africans (SABPA) study were included in this sub-study. Ambulatory pulse pressure and intraocular perfusion pressures were obtained, while metabolic variables and testosterone were measured from fasting venous blood samples. Retinal vascular calibre was quantified from digital photographs using standardised protocols. The black men revealed a poorer cardiometabolic profile and higher pulsatile pressure (>50 mm Hg), intraocular pressure and diastolic ocular perfusion pressure than the white men (p≤0.05). Only in the white men was free testosterone positively associated with retinal calibre, i.e. arterio-venular ratio and central retinal arterial calibre and inversely with central retinal venular calibre. These associations were not found in the black men, independent of whether pulse pressure and ocular perfusion pressure were part of the model. These results suggest an independent, protective effect of testosterone on the retinal vasculature where an apparent vasodilatory response in the retinal resistance microvessels was observed in white men.

Bioavailable IGF-1 and its relationship with endothelial damage in a bi-ethnic population: The SABPA study

IntroductionInsulin-like growth factor-1 (IGF-1) has vasculoprotective effects and can directly oppose endothelial dysfunction in several ways. To improve our understanding on the potential contribution of reduced IGF-1 to the development of vascular endothelial damage, we investigated the link between bioavailable IGF-1 and von Willebrand factor (vWF) as a marker of endothelial damage. We performed this study in black South African school teachers, known to be prone to hypertension. Materials and methodsFrom the larger Sympathetic activity and Ambulatory Blood Pressure in Africans (SABPA) study we included 179 black and 207 white non-diabetic men and women (aged 44.5±9.96years). We measured ambulatory blood pressure and determined IGF-1, insulin-like growth factor binding protein 3 (IGFBP-3) and vWF antigen from blood samples. We used the molar IGF-1/IGFBP-3 ratio as an estimate of bioavailable IGF-1. ResultsBlack individuals presented higher blood pressure and vWFag and lower IGF-1 than the white group (all p<0.001). In multivariate-adjusted analyses, vWFag was inversely associated with IGF-1 (R2=0.18; β=−0.17; p=0.044) and IGF-1/IGFBP-3 (R2=0.18; β=−0.17; p=0.030) in blacks, with no associations in whites. Since IGF-1 is attenuated and vWFag elevated in diabetes, we included patients with diabetes (n=38) and the aforementioned associations found in blacks remained robust. ConclusionThe inverse association between bioavailable IGF-1 and vWF in black South Africans suggests that suppressed IGF-1 may result in endothelial damage independent of traditional risk factors.

Defensive coping and renovascular disease risk — Adrenal fatigue in a cohort of Africans and Caucasians: The SABPA study

BackgroundDefensive coping is an established cardiovascular risk factor in Africans. Additionally, chronic, excessive or inadequate hypothalamic–pituitary–adrenal axis (HPAA) stress responses could either increase or decrease cortisol responses, which may relate to renal impairment. We scrutinised the relationship between urinary cortisol levels and renovascular disease risk in Africans and Caucasians utilising defensive coping. MethodsAfricans (n=168) and Caucasians (n=207) from the SABPA (Sympathetic activity and Ambulatory Blood Pressure in Africans) study were included in our analyses, excluding HIV positive, diabetic, renal impairment, and cortisone users. The Coping Strategy Indicator questionnaire assessed preferred coping responses. Ambulatory blood pressure was recorded together with 8h fasting blood and urine sampling. Renovascular disease risk markers included the albumin-to-creatinine ratio (ACR) and estimated glomerular filtration rate (eGFR). ResultsThe main findings revealed that Caucasians with high cortisol showed augmented renovascular disease risk. Conversely, Africans revealed low cortisol levels whilst 21.84% reported experience of severe stress, possibly depicting HPAA hypoactivity. Additionally, these Africans with low cortisol revealed increased ACR and decreased eGFR, which was further enhanced by defensive coping. ConclusionsDefensive coping enhanced renovascular risk in Africans, especially in those with lower cortisol, which may be due to HPAA dysfunction and/or adrenal fatigue.

Cohort Profile: Sympathetic activity and Ambulatory Blood Pressure in Africans (SABPA) prospective cohort study.

Adapting to an over-demanding stressful urban environment may exhaust the psychophysiological resources to cope with these demands, and lead to sympathetic nervous system dysfunction. The evidence that an urban-dwelling lifestyle may be detrimental to the cardiometabolic health of Africans motivated the design of the Sympathetic activity and Ambulatory Blood Pressure in African Prospective cohort study. We aimed to determine neural mechanistic pathways involved in emotional distress and vascular remodelling. The baseline sample included 409 teachers representing a bi-ethnic sex cohort from South Africa. The study was conducted in 2008–09 and repeated after 3-year follow-up in 2011–12, with an 87.8% successful follow-up rate. Seasonal changes were avoided and extensive clinical assessments were performed in a well-controlled setting. Data collection included sociodemographics, lifestyle habits, psychosocial battery and genetic analysis, mental stress responses mimicking daily life stress (blood pressure and haemostatic, cardiometabolic, endothelial and stress hormones). Target organ damage was assessed in the brain, heart, kidney, blood vessels and retina. A unique highly phenotyped cohort is presented that can address the role of a hyperactive sympathetic nervous system and neural response pathways contributing to the burden of cardiometabolic diseases in Africans.

Determining ethnic-, gender-, and age-specific waist circumference cut-off points to predict metabolic syndrome: the Sympathetic Activity and Ambulatory Blood Pressure in Africans (SABPA) study

Objective: The aim was to determine receiver-operating characteristic (ROC) waist circumference (WC) cut-off points best associated with metabolic syndrome (MetS) in a cohort of South African teachers. Design: Target population study. Setting and subjects: Four hundred and nine urban black (Africans) and white (Caucasians) from the Kenneth Kaunda district in North West province, between the ages of 25 and 65 years old, were stratified according to gender and age (25-45 years and 46-65 years). Outcome measures: Anthropometric, fasting overnight urine and biological markers for MetS. Results: ROC analysis determined pathological WC cut-off points of 91 cm for African men and 84 cm for African women. It is recommended that WC cut-off points should be 97 cm for Caucasian men and 84 cm for Caucasian women. Pathological WC cut-off points significantly predicted MetS in all ethnic-, gender- and age- specific groups, especially in male groups, with odds ratios of 7.6 [95% confidence interval (CI): 3.4-17.1, p-value = 0.00) for African men and 6 (95% CI: 3-12.1, p-value = 0.00) for Caucasian men. Conclusion: ROC-developed WC cut-off points were found to be good predictors of MetS in a South African cohort, especially in the men. Further research in prospective cohort studies is warranted to verify our findings.

End-organ damage in urbanized Africans with low plasma renin levels: the SABPA study

The purpose of this study was to evaluate whether active renin concentration is associated with markers of end-organ damage in urbanized Africans. This study forms part of the Sympathetic Activity and Ambulatory Blood Pressure in Africans (SABPA) study. For this study, 81 men and 74 women were divided into low- and high-renin groups. Ambulatory blood pressure measurements were conducted. A resting 12-lead ECG was determined in order to determine the gender-specific Cornell voltage. Cardiovascular variables were continuously recorded with the Finometer. Carotid-dorsalis pedis pulse wave velocity was obtained with the Complior acquisition system. The carotid intima-media thickness (CIMT) was obtained with the SonoSite MicroMaxx. Blood samples were collected; serum and plasma were stored at −80 °C for analysis. Anthropometric measurements were taken using standard methods. A general health questionnaire was also completed. The urinary creatinine was determined with a calorimetric method and albumin with a turbidimetric method. The serum sodium and potassium were determined by making use of the Konelab TM 20i Sequential Multiple Analyzer Computer (SMAC). The concentration of active renin in the plasma was analyzed by making use of a high-sensitivity radio-immunometric assay. A negative association (r = −0.29, p < 0.01) exists between renal function (ACR) and plasma renin in the low-renin group (<6.18 pg/mL), which was not observed in Africans with high-renin levels. It seems evident that low renin in black South Africans may result in sub-clinical renal damage and impaired vascular function in a group of urbanized black South Africans.

Low Testosterone and Hyperkinetic Blood Pressure Responses in a Cohort of South African Men: The SABPA Study

Hypertension (HT) and the metabolic syndrome are major problems in Africa. The role of sex hormones in the cardiovascular profile of black Africans in South Africa has not been studied. Our objective was to study the association between the sex hormones and ambulatory blood pressure and the heart rate (HR) in black and white South Africans. The 24-hour ambulatory blood pressure measurements were performed and the blood samples were taken between 07:00 and 09:00 hours. A total of 80 black and 98 white South African teachers between 25 and 65 years of age from similar socioeconomic backgrounds from the Sympathetic Activity and Ambulatory Blood Pressure in Africans (SABPA) study were included. As a result, a more vulnerable cardiovascular profile was observed in Africans compared with Caucasians. In the African group, low testosterone (T) explained 19%–36% of the variance in systolic blood pressure (SBP), diastolic blood pressure (DBP), and HR, whereas in the Caucasian group non-sex-hormone-binding globulin (non-SHBG)-bound T explained 27% of the variance in HR. In the African males, inverse associations between blood pressure and T (SBP: P = .08; DBP: P = .02) and non-SHBG-bound T (SBP: P < .001; DBP: P < .01) and HR (P < 0.01) were observed. Ambulatory HR predicted a prediabetic state in Africans. In conclusion, low T levels may predispose or result in impaired cardiovascular function in African men. The possibility exists that a prediabetic state, vagal-impaired HR, and hyperkinetic blood pressure responses may predispose or result in low T levels in African men.

Association of waist circumference with perception of own health in urban African males and females: the Sympathetic Activity and Ambulatory Blood Pressure in Africans (SABPA) study

Background: Current waist circumference (WC) cut-points of the Joint Statement Consensus (JSC) (male ≥ 94 cm, female ≥ 80 cm) were compared with a recently proposed WC cut-point (RPWC) (male ≥ 90 cm, female ≥ 98 cm). In this study, we aimed to compare the two cut-points to assess the association between central obesity and perception of own health. Method: We determined blood pressure and fasting bloods [glucose, high-density lipoprotein (HDL) and triglycerides] as metabolic syndrome markers for 171 urban teachers. Perception of own health was determined via the General Health Questionnaire-28 (GHQ-28) to indicate probable psychological distress or a psychiatric disorder or caseness (≥ 4). Results: The RPWC was an improved discrimination between the WC groups on perception of own health as reflected in the GHQ-28 subscales. In the male group, higher scores were found in the RPWC high WC group (≥ 90 cm) with regard to somatic symptoms, social dysfunction and GHQ-28 caseness, compared to those of the low WC groups (< 90 cm). Compared to the RPWC high WC females (≥ 98 cm), the low WC (< 98 cm) reflected significantly higher anxiety and sleeplessness subscale scores. Conclusion: Our results suggest that the RPWC (men 90 cm, women 98 cm), (determined in this African cohort when adding GHQ-28 caseness as a discriminatory variable between WC cut-point), distinguished better between WC groups based on their perception of own health than the JSC cut-point.

Metabolic Syndrome Indicators and Target Organ Damage in Urban Active Coping African and Caucasian Men: The SABPA Study

Psychosocial stress relating to an urban environment or acculturation increases the prevalence of metabolic syndrome (MetS). The objectives of this study were firstly to indicate and compare differences regarding appraisal of stress or active coping responses in urban African (n=88) and Caucasian (n=101) male teachers of South Africa, in accord with the prevalence of MetS indicators. And secondly to investigate the extent to which utilisation of active coping responses, together with MetS indicators, predict target organ damage, in these men. The Coping Strategy Indicator determined high and low active coping responses in male teachers from the Sympathetic Activity and Ambulatory Blood Pressure in Africans (SABPA) study. SABPA inclusion and exclusion criteria were used. Additionally, diabetic medication users (n=8), and participants with renal impairment (n=2) or HIV positive (n=13), were excluded. MetS indicators included glucose, triglyceride, high-density lipoprotein cholesterol, blood pressure, and waist circumference, independent of confounders (age, physical activity, gamma glutamyl transferase). Microalbuminuria and carotid intima-media thickness indicated target organ damage. More MetS indicators exceeded the IDF cut-off points in high active coping African men (14.71%) than in their Caucasian counterparts (3.33%), as determined from χ² analyses. Furthermore, stepwise regressions indicated that more MetS indicators predicted endothelial dysfunction, especially in the high active coping African men. High active coping African men showed more manifestation of MetS, compared to their Caucasian counterparts, and revealed progress towards endothelial dysfunction.

Depressive symptoms and sub-clinical atherosclerosis in Africans: Role of metabolic syndrome, inflammation and sympathoadrenal function

Depressive symptoms have been consistently associated with sub-clinical atherosclerosis and future risk of coronary heart disease events. However, the pathways linking depression and coronary atherosclerosis are poorly understood. These types of data are particularly sparse in sub-Saharan Africa, which is presently experiencing an exponential rise in CVD. We examined the association between depressive symptoms and mean carotid intima media thickness (mCIMT), and the extent to which this association could be explained by sympathoadrenal function, inflammatory, and metabolic pathways. A sample of 186 black (aged 44.0±8.0years) and 203 Caucasians (aged 44.8±10.8years) were recruited as part of the Sympathetic Activity and Ambulatory Blood Pressure in Africans (SABPA) study — presently the only study in sub-Saharan Africa focusing on the contribution of the psychosocial risk factors to cardiovascular health. Depressive symptoms were assessed using the self administered 9-item Patient Health Questionnaire. After adjusting for age, sex, ethnicity, and anti-hypertensive drugs use, participants with severe depressive symptoms had higher mCIMT in comparison to participants with no symptoms (β=0.038mm, 95% CI, 0.001 to 0.074mm). Metabolic syndrome was the only significant mediator of the association between depressive symptoms and mCIMT, and accounted for approximately 21% of the effect. In summary, depressive symptoms were associated with an excess burden of sub-clinical vascular disease. Treatment of metabolic syndrome in patients with depression may partly reduce the risk of sub-clinical vascular disease development.