The role of feature-based discrimination in driving health disparities among Black Americans.

Objective: A growing body of research finds that darker skin tone is often associated with poorer physical and mental health in Blacks. However, the psychosocial mechanisms underlying the skin tone-health link remain elusive. The present study seeks to address this knowledge gap by investigating the direct and indirect (through perceived discrimination, socioeconomic status, and self-esteem) effects of skin tone on self-reported physical and mental health.Design: An urban sample of 130 Blacks aged 35 and above completed a self-administered computerized survey as a part of larger cross-sectional study.Results: Self-esteem played a particularly important role in mediating the associations between skin tone and self-reported physical and mental health. This suggests that self-esteem could be a point of intervention to help Blacks with darker skin tone achieve better health.Conclusion: The present study highlights the important role feature-based discrimination plays in determining mental and physical health outcomes among Blacks.

Kinetic and theoretical comprehension of diverse rate laws and reactivity gaps in Coriolus hirsutus laccase-catalyzed oxidation of acido and cyclometalated Ru(II) complexes.

The reactivity of the acido Ru(II) complexes cis-[RuCl(2)(LL)(2)], [RuCO(3)(LL)(2)], cis-[RuCO(3)-(bquin)(2)] (LL = 2,2'-bipyridine (bpy) and 1,10-phenanthroline (phen); bquin = 2,2'-biquinoline) and cyclometalated Ru(II) derivatives of 2-phenylpyridine and 4-(2-tolyl)pyridine [Ru(o-C(6)H(4)-2-py)(phen)(2)]PF(6) (1), [Ru(o-C(6)H(3)-p-R-2-py)(bpy)(MeCN)(2)]PF(6) (2), and [Ru(o-C(6)H(3)-p-R-2-py)(phen)(MeCN)(2)]PF(6) (3) (R = H (a), Me (b)) toward laccase from Coriolus hirsutus has been investigated by conventional UV-vis spectroscopy at pH 3-7 and 25 degrees C. The acido and cyclometalated complexes are readily oxidized into the corresponding Ru(III) species, but the two types of complexes differ substantially in reactivity and obey different rate laws. The acido complexes are oxidized more slowly and the second-order kinetics, first-order in laccase and Ru(II), holds with the rate constants around 5 x 10(4) M(-1) s(-1) at pH 4.5 and 25 degrees C. The cyclometalated complexes 1-3 react much faster and the hyperbolic Michaelis-Menten kinetics holds. However, it is not due to formation of an enzyme-substrate complex but rather because of the ping-pong mechanism of catalysis, viz. E(ox) + Ru(II) --> E(red) + Ru(III) (k(1)); E(red) + 1/4O(2) --> E(ox) (k(2)), with the rate constants k(1) in the range (2-9) x 10(7) M(-1) s(-1) under the same conditions. The huge values of k(1) move the enzymatic oxidation toward a kinetic regime when the dioxygen half-reaction becomes the rate-limiting step. Cyclometalated compounds 1-3 can therefore be used for routine estimation of k(2), that is, the rate constant for reoxidation for laccases by dioxygen. The mechanism proposed was confirmed by the direct stopped-flow measurements of the k(2) rate constant (8.1 x 10(5) M(-1) s(-1) at 26 degrees C) and supported by the theoretical modeling of interaction between the bpy analogue of 1 and Coriolus hirsutes laccase using Monte Carlo simulations.