The relation of blood pressure and carotid intima-media thickness with the glutathione cycle in a young bi-ethnic population: the African-PREDICT study

Left ventricular mass and urinary metabolomics in young black and white adults: The African-PREDICT study

BACKGROUND AND AIMS

Increased left ventricular mass is an independent predictor for cardiovascular events, and shown to be higher in black than white populations. To gain a better understanding of early factors contributing to increased left ventricular mass in young black adults, we investigated metabolomic profiles, identified and compared metabolites that associated with left ventricular mass index in healthy black and white adults.

METHODS AND RESULTS

We included normotensive black and white participants from the African-PREDICT study, with data on urinary metabolomics and echocardiography. Urinary metabolites were measured using three different analytical platforms. Univariate statistical analyses, including independent t-test (adjusted for multiple comparisons), effect size (d ≥ 0.3) and single regression analyses were used to identify metabolites. When comparing the black and white groups, the black group had higher central systolic blood pressure (p > 0.005), whereas left ventricular mass index was similar between the groups (p = 0.97). Three from a total of 192 metabolites were identified to be more abundant (p < 0.046) and inversely associated with left ventricular mass index in the black group only: hydroxyproline (β = -0.22; p = 0.045), glycine (β = -0.20; p = 0.049) and trimethylamine (β = -0.21; p = 0.037).

CONCLUSION

Higher urinary levels of hydroxyproline, glycine and trimethylamine were inversely associated with left ventricular mass index in the black adults only. Hydroxyproline and glycine are important in maintaining healthy collagen turnover and stability in the heart. Our results may reflect an increase in collagen biosynthesis and collagen deposition in the left ventricle due to higher central systolic blood pressure in the black population.

Three-year change in oxidative stress markers is linked to target organ damage in black and white men: the SABPA study

Oxidative stress is implicated in hypertension, carotid wall thickening, and renal dysfunction. Oxidative stress is linked to cardiovascular pathology in the black South African individuals who have a high prevalence of hypertension and early vascular aging. However, there are limited data relating changes in oxidative stress with vascular and renal deterioration over time. We aimed to investigate whether changes in oxidative stress over 3 years are associated with target organ damage in black (N = 89) and white (N = 91) men. Carotid intima-media thickness was measured using the SonoSite Micromaxx ultrasound system, and cross-sectional wall area (CSWA) was calculated. The estimated glomerular filtration rate (eGFR) was calculated using the Modification of Diet in Renal Disease formula. The percentage change (%∆) in oxidative stress markers was calculated and included reactive oxygen species (ROS), superoxide dismutase (SOD), glutathione peroxidase (GPx), and glutathione reductase (GR). Over 3 years, black men exhibited decreased ROS, SOD, and GR, while white men revealed decreased SOD and GPx. Black men displayed positive associations of CSWA with %∆ ROS (β = 0.28; p = 0.017) and %∆ SOD (β = 0.24; p = 0.047). White men displayed a negative association of CSWA with %∆ SOD (β = -0.22; p = 0.042) and positive associations of eGFR with %∆ GPx (β = 0.33; p = 0.001) and %∆ GR (β = 0.39; p < 0.001). In white men, the association of CSWA with decreased SOD activity suggests oxidative-stress-related carotid remodeling, while associations of eGFR with the glutathione system suggests a postponement of microvascular deterioration. In black men, associations of oxidative stress markers with CSWA suggest that a sufficiently functioning antioxidant system may delay target organ damage.