Extended afternoon naps are associated with hypertension in women but not in men
BACKGROUND:The impact of afternoon napping duration on the risk of hypertension has not been well established, particularly with regards to sex and age differences. OBJECTIVE:To examine the association between afternoon napping duration and hypertension stratified by sex and age among Chinese adults over 45 years of age. METHODS:The 2011-2012 survey of the China Health and Retirement Longitudinal Study (CHARLS) was used, including 7,980 participants. We conducted logistic regression models in the overall sample, and then stratified by sex and age groups. RESULTS:Middle-aged and older women who napped over 90Â min were 39% and 54% more likely to have hypertension, respectively; however, the associations were not significant in middle-aged and older men. CONCLUSION/CONCLUSIONS:Extended afternoon napping (â‰¥90Â min) was associated with hypertension in both the middle-aged women and older women but not in men. Future studies are needed to further examine the association and possible mechanisms.
Wall modes in magnetoconvection at high Hartmann numbers
Three-dimensional turbulent magnetoconvection at a Rayleigh number of Ra = 107 in liquid gallium at a Prandtl number Pr = 0:025 is studied in a closed square cell for very strong external vertical magnetic fields B0 in direct numerical simulations which apply the quasistatic approximation. As B0, or equivalently the Hartmann number Ha, are increased, the convection flow, which is highly turbulent in the absence of magnetic fields, crosses the Chandrasekhar linear stability limit for which thermal convection ceases in an infinitely extended layer and which can be assigned a critical Hartmann number Hac. Similar to rotating Rayleigh-BÃ©nard convection, our simulations reveal subcritical sidewall modes that maintain a small but finite convective heat transfer for Ha > Hac. We report a detailed analysis of the complex two-layer structure of these wall modes, their extension into the cell interior, and a resulting sidewall boundary layer composition that is found to scale with the Shercliff layer thickness
MDR1 genotype is associated with hepatic cytochrome P450 3A4 basal and induction phenotype
OBJECTIVES/OBJECTIVE:Variant cytochrome P450 (CYP) 3A4 alleles cannot explain human variation in CYP3A4 expression. This study investigated whether common single-nucleotide polymorphisms (SNPs) in multidrug resistance 1 (MDR1), encoding P-glycoprotein, or the pregnane X receptor (PXR) were associated with basal or inducible CYP3A4 expression. METHODS:MDR1 G2677T and C3435T SNPs and a PXR 6-base pair (bp) deletion were genotyped in the deoxyribonucleic acid from 144 human livers in 3 cohorts each phenotyped for basal or rifampin (INN, rifampicin)-inducible hepatic CYP3A4 expression (or both) and in 57 human small bowel biopsy specimens from 3 cohorts each phenotyped for either basal or rifampin-induced CYP3A4 expression (or both). RESULTS:Hepatic CYP3A4 expression/function was significantly higher in persons homozygous for the MDR1 2677T (Ser893) allele compared with persons homozygous for 2677G (Ala893) in all 3 hepatic cohorts. For example, homozygous MDR1 2677 TT livers had higher midazolam hydroxylase activity than homozygous 2677 GG livers (1831 +/- 1336 pmol x min(-1) x mg protein(-1) versus 1060 +/- 552 pmol x min(-1) x mg protein(-1), P = .03). In 2 of the 3 groups the association was observed in men but not in women. For example, homozygous MDR1 2677 TT male hepatocytes had significantly higher testosterone 6beta-hydroxylase activity compared with homozygous 2677 GG livers (0.120 +/- 0.06 pmol x min(-1) x mg protein(-1) versus 0.069 +/- 0.04 pmol x min(-1) x mg protein(-1), P = .0002). Conversely, rifampin induction of testosterone 6beta-hydroxylation in primary human hepatocytes was significantly higher in persons homozygous for 2677G (12.0 +/- 5.7-fold) compared with MDR1 homozygous TT carriers (7.3 +/- 4.6-fold) (P = .01). Suggestive evidence for higher CYP3A4 expression in MDR1 2677T carriers was also observed in human intestines. CYP3A4 expression was also related to a 6-bp deletion in PXR in 2 of the liver cohorts. Two-factor ANOVA analysis revealed a significant interaction between the MDR1 2677 SNP and the PXR 6-bp deletion influencing CYP3A4 expression (P = .007). CONCLUSIONS:Individuals homozygous for the MDR1 2677T allele show enhanced constitutive CYP3A4 expression in the liver and intestine, as compared with those homozygous for the MDR1 2677G allele, particularly in men. Conversely, the magnitude of CYP3A4 induction by rifampin is greater in persons with the MDR1 2677G allele and is inversely related to baseline CYP3A4 expression. MDR1 likely influences basal CYP3A4 expression by limiting the intracellular concentration of an endogenous regulator. MDR1 genotype may be a useful predictor of basal CYP3A4 and the extent of some CYP3A4-mediated drug interactions in humans. Moreover, the influence of MDR1 genotype on CYP3A4 expression adds additional complexity to determining the relative contribution of the MDR1 alleles to the disposition of substrates shared by CYP3A4 and MDR1/P-glycoprotein.