Hypertension in Africa: Redressing the burden of cardiovascular disease using cost-effective nonpharmacological approaches

Hypertension may affect approximately one fifth or more of all adult South Africans. Despite the considerable evidence derived from economically developed countries to indicate the extent to which hypertension contributes to cardiovascular disease (CVD), it is only more recently that data has emerged from the African continent to support a contention that hypertension is the principal risk factor for CVD in African populations and that CVD accounts for a major proportion of deaths in the elderly and in younger adults in rural Africa. Active engagement in the harsh realities of managing this complex clinical trait should therefore be foremost on the minds of the healthcare sector in Africa. In this regard there are unique challenges. In the present personal review we synthesise the evidence for or against the view that at a public health level, the answer to significantly reducing the burden of CVD produced by hypertension in African populations, may lie in something as simple as generating a healthier lifestyle. In this regard, we place recent evidence obtained from South African studies of the importance of modifiable cardiovascular risk factors related to hypertension, including salt intake and obesity, in the context of previously published evidence. We highlight the very recent and the first substantive evidence derived from an African community to show that salt intake indeed contributes to a significant portion of blood pressure (BP) variability in African populations, but this effect may be hidden because the impact is largely on central (aortic) rather than brachial BP. We also discuss the increasing evidence to show that in African populations, the adverse effects of the epidemic of obesity that faces emerging communities is likely to account for a substantial proportion of cardiovascular risk not through marked effects on brachial BP, but through indirect effects by promoting the adverse effects of BP on the heart. In the present review we therefore argue that despite limited absolute effects of salt intake and obesity on brachial BP, a marked benefit could be gained by the BP effects of salt restriction and body weight reduction in African communities

Rheumatoid arthritis is associated with reduced adiposity but not with unfavorable major cardiovascular risk factor profiles and enhanced carotid atherosclerosis in black Africans from a developing population: a cross-sectional study

INTRODUCTION: Rheumatoid arthritis (RA) is characterized by inflamed joint-derived cytokine-mediated high-grade systemic inflammation that enhances cardiovascular metabolic risk and disease in developed populations. We investigated the potential impact of RA on cardiovascular risk factors including systemic inflammation and atherosclerosis, and their relationships in black Africans from a developing population. METHODS: We evaluated demographic features, adiposity indices, major traditional cardiovascular risk factors, circulating C-reactive protein and interleukin-6 concentrations and ultrasound determined carotid intima-media thickness (cIMT) in 274 black Africans; 115 had established RA. Data were analyzed in confounder-adjusted mixed regression models. RESULTS: The body mass index and waist-height ratio were lower in RA compared to non-RA subjects (29.2 (6.6) versus 33.7 (8.0), P < 0.0001 and 0.58 (0.09) versus 0.62 (0.1), P = 0.0003, respectively). Dyslipidemia was less prevalent in patients with RA (odds ratio (OR) (95% confidence interval (CI) = 0.54 (0.30 to1.00)); this disparity was no longer significant after further adjustment for reduced adiposity and chloroquine use. RA was also not associated with hypertension, current smoking and diabetes. The number of major traditional risk factors did not differ by RA status (1.1 (0.8) versus 1.2 (0.9), P = 0.7). Circulating C-reactive protein concentrations were similar and serum interleukin-6 concentrations reduced in RA (7.2 (3.1) versus 6.7 (3.1) mg/l, P = 0.7 and 3.9 (1.9) versus 6.3 (1.9) pg/ml, P < 0.0001, respectively). The cIMT was 0.700 (0.085) and 0.701 (0.111) mm in RA and non-RA subjects, respectively (P = 0.7). RA disease activity and severity parameters were consistently unrelated to systemic inflammation, despite the presence of clinically active disease in 82.6% of patients. In all participants, adiposity indices, smoking and converting angiotensin inhibitor non-use were associated with increased systemic inflammation, which related to more atherogenic lipid profiles, and circulating low density lipoprotein concentrations were associated with cIMT (partial R = 0.153, P = 0.032); RA did not impact on these relationships (interaction P ≥0.1). CONCLUSIONS: Among black Africans, patients with established RA experience reduced overall and abdominal adiposity but no enhanced major traditional risk factor and atherosclerosis burden. This study further suggests that an absent interleukin-6 release by inflamed RA joints into the circulation may account for this unaltered cardiovascular disease risk

Impact of dietary-induced obesity on adrenergic-induced cardiomyocyte damage in rats

Although obesity is an independent risk factor for heart failure and even mild-to-moderate forms of obesity are associated with myocardial systolic dysfunction the mechanisms of the myocardial dysfunction have not been identifi ed. We assessed whether dietary-induced obesity is associated with an increased sensitivity of the myocardium to ß-adrenergic-induced cardiomyocyte apoptosis or fibrosis. To induce obesity, rats were fed a diet that promotes an increased caloric intake. Adrenergic-induced cardiomyocyte apoptosis was determined by injecting rats for 5 days with isoproterenol (0.01 mg/kg/day for 3 days and 0.02 mg/kg/day for 2 days) and then studying the degree of cardiomyocyte damage using a TUNEL assay and assessing the pathological score. Five months of feeding rats a diet that promoted the development of an increased body weight (Control=481±4.3 g, Diet=550±7.8 g, p‹0.001) and visceral fat content (Control=19.6±0.8 g, Diet=33.0±1.2 g, p‹0.0001), did not alter baseline cardiomyocyte apoptosis. However, 5 days of ß-adrenergic activation resulted in an enhanced cardiomyocyte apoptosis in rats receiving the experimental diet as compared to rats receiving a normal diet (p‹0.01). No changes in the myocardial pathological score (fibrosis) were noted. The enhanced adrenergic-induced cardiomyocyte apoptosis in obese rats could not be explained by dietary-induced increases in baseline left ventricular internal diameters, decreases in systolic function (endocardial or midwall fractional shortening) or differences in the response of the heart to adrenergic-induced increases in inotropic or chronotropic function. In conclusion, the present study suggests that obesity may contribute to myocardial dysfunction by increasing the sensitivity of the myocardium to adrenergic-induced cardiomyocyte damage

The relationship between the nitric oxide synthase gene and the risk of hypertension defi ned according to ambulatory blood pressures

Although nitric oxide (NO) plays an important role in blood pressure (BP) control, whether variation of genes involved in regulating the synthesis of NO infl uences BP is uncertain. As the heritability of BP is stronger for ambulatory than it is for conventional BP, we assessed the independent association of the well described functional exon 7 Glu298Asp variant of the eNOS gene with the presence of hypertension in 511 randomly selected normotensive control participants and 503 hypertensives with a diagnosis of hypertension confi rmed with 24-hour ambulatory BP profiles whilst off therapy. We also assessed the relationship between eNOS genotype and 24 hour ambulatory BP. Comparisons of genotype and allele frequencies indicated a lack of association of the exon 7 Glu298Asp gene variant with hypertension (Odds ratio of genotype predicting the presence of hypertension=0.97, confidence interval=0.70-1.30, p=0.92). However, patients with the Glu/Glu genotype of the Glu298Asp variant (n=424) had increased 24-hour systolic and diastolic blood pressures (152±1/97±1 mm Hg) in comparison to patients heterozygous for the Glu298Asp variant or homozygous for the 298Asp allele (n=79) (145±1/94±1 mm Hg, p‹0.005 for systolic BP and p‹0.001 for diastolic BP after multiple adjustments including age, gender, body mass index and the presence of diabetes mellitus). Differences in systolic and diastolic BP between genotype groups were noted during the day as well as at night. The association of eNOS genotype with ambulatory BP translated into an increased risk of more severe grades of hypertension in patients with the Glu/Glu genotype (grade II and III vs. grade I, Odds ratio=2.20, confidence interval=1.34-3.59, p‹0.0002). In conclusion, a functional gene variant (Glu298Asp) at the eNOS locus contributes ~1.4-2.5% to the variation in ambulatory blood pressure within hypertensives, but is not associated with the presence of hypertension in patients in whom the diagnosis has been confirmed by 24-hour ambulatory BP values. The relationship between eNOS genotype and 24-hour ambulatory BP and the severity of hypertension warrants further study

IJTC2007-44218 Studies on ZDDP anti-wear films formed under the different conditions by XANES spectroscopy, atomic force microscopy and 31P NMR

ABSTRACT Antiwear (AW) films, generated from a mineral base oil containing zinc dialkyl dithiophosphate (ZDDP) additive, were extensively studied. These films were formed at various conditions such as different temperatures, various loads and rubbing times. The surface morphology of these films was investigated using atomic force microscopy (AFM) and the surface roughness of these films has been calculated from the images. X-ray absorption near edge structure (XANES) spectroscopy has been used to characterize the chemistry of these films. The intensity of phosphorus K-edge was also used to monitor the thickness of these films. Phosphorus L-edge spectra show that these films have slightly variable chemical natures. 31P Nuclear magnetic resonance (31P NMR) was used to study the ZDDP components in the residue oils. The spectra show that the primary and secondary ZDDP decompose quite differently at the various conditions. Tribological characteristics of these AW films were probed by measuring the coefficients of friction and the wear scar width of the counter faces

Supported by The South African Medical Research Council (grant MRC2008_DES) and National Research Foundation

ABSTRACT. Objective. Depending on physiological context, the adipokine chemerin can reduce or enhance cardiovascular risk. We investigated whether chemerin concentrations represent cardiovascular disease risk in rheumatoid arthritis (RA). Methods. We assessed ELISA-determined chemerin concentrations and those of 4 early endothelial activation molecules as well as angiopoietin 2, which mediates angiogenesis and thereby contributes to advanced atherosclerosis, the common carotid artery intima-media thickness (cIMT), and carotid artery plaque by ultrasound in 236 patients (114 black and 122 white) with RA. Relationships were identified in potential confounder and mediator-adjusted mixed regression models. . The β (SE) for the chemerin-intima-media thickness relations in patients with overweight or generalized obesity and abdominal obesity were larger than in those without these characteristics (p &lt; 0.0001 and = 0.04, respectively). Conclusion. Chemerin is associated with endothelial activation and atherosclerosis in RA. Adiposity influences the chemerin-atherosclerotic phenotype relations i

Impact of initiating carvedilol before angiotensin-converting enzyme inhibitor therapy on cardiac function in newly diagnosed heart failure

ObjectivesThe purpose of this research was to evaluate the therapeutic value of initiating a beta-blocker before an angiotensin-converting enzyme inhibitor (ACEI) in the treatment of heart failure.BackgroundAlthough ACEI and carvedilol produce benefits in heart failure, whether the order of initiation of therapy determines the impact on left ventricular (LV) function and New York Heart Association functional class (NYHA FC) has not been determined.MethodsA single-center, prospective, randomized, open-label study was performed. We evaluated whether initiation of therapy with carvedilol either before (n = 38) or after (n = 40) perindopril therapy in newly diagnosed patients in NYHA FC II to III heart failure with idiopathic dilated cardiomyopathy, with the addition of the alternative agent after six months, determined subsequent changes in NYHA FC and LV function (echocardiography and radionuclide ventriculography). Study drugs were titrated to maximum tolerable doses.ResultsThere were no differences in baseline characteristics between the study groups. After 12 months 11 patients died (6 in the group where the ACEI was initiated). At 12 months the group receiving carvedilol as initial therapy achieved a higher tolerable dose of carvedilol (43 ± 17 mg vs. 33 ± 18 mg, p = 0.03); a lower dose of furosemide (p &lt; 0.05); and better improvements in symptoms (NYHA FC, p &lt; 0.002), LV ejection fraction (radionuclide: 15 ± 16% vs. 6 ± 13%, p &lt; 0.05; echocardiographic, p &lt; 0.01), and plasma N-terminal pro-brain natriuretic peptide concentrations (p &lt; 0.02).ConclusionsAs opposed to the conventional sequence of drug use in the treatment of heart failure, initiation of therapy with carvedilol before an ACEI results in higher tolerable doses of carvedilol and better improvements in FC and LV function

The Impact of Different Classification Criteria Sets on the Estimated Prevalence and Associated Risk Factors of Diastolic Dysfunction in Rheumatoid Arthritis

This study compared the estimated prevalence and potential determinants of left ventricular (LV) diastolic dysfunction upon applying different classification criteria in rheumatoid arthritis (RA). LV diastolic function was assessed echocardiographically by pulsed Doppler (E/A), tissue Doppler (E/e′, lateral and septal e′), and left atrial volume index in 176 RA patients. Relationships of traditional cardiovascular risk factors and RA characteristics with LV diastolic function and dysfunction according to previous and current criteria were determined in multivariate regression models. Waist-hip ratio was associated with E/A (standardised β (SE) = -0.28±0.09, p=0.0002) and lateral e′ (standardised β (SE) = 0.26±0.09, p=0.01); low diastolic blood pressure was related to E/e′ (standardised β (SE) = -0.16±0.08, p=0.04). Diastolic dysfunction prevalence differed upon applying previous (59%) compared to current (22%) criteria (p<0.0001). One SD increase in waist-hip ratio was associated with diastolic dysfunction when applying current criteria (OR = 2.61 (95% CI = 1.51–4.52), p=0.0006), whereas one SD increase in diastolic blood pressure was inversely related to diastolic dysfunction upon using previous criteria (OR = 0.57 (95% CI = 0.40–0.81), p=0.002). In conclusion, application of current and previous diastolic dysfunction criteria markedly alters the prevalence and risk factors associated with diastolic dysfunction in RA