Background

African American smokers have 2.5 times higher risk for stroke compared with nonsmokers (higher than other races). About 50% of the African American population carry 1 or 2 genetic variants (G1 and G2; rare in other races) of the apolipoprotein L1 gene (APOL1). Studies showed these variants may be associated with stroke. However, the role of the APOL1 risk variants in tobacco-related stroke is unknown.

Methods and results

In a cross-sectional study, we examined whether APOL1 risk variants modified the relationship between tobacco smoking and stroke prevalence in 513 African American adults recruited at University of California, San Francisco. Using DNA, plasma, and questionnaires we determined APOL1 variants, smoking status, and stroke prevalence. Using logistic regression models, we examined the association between smoking (ever versus never smokers) and stroke overall, and among carriers of APOL1 risk variants (1 or 2 risk alleles), and noncarriers, separately. Among participants, 41% were ever (current and past) smokers, 54% were carriers of the APOL1 risk variants, and 41 had a history of stroke. The association between smoking and stroke differed by APOL1 genotype (P_{interaction term}=0.014). Among carriers, ever versus never smokers had odds ratio (OR) 2.46 (95% CI, 1.08-5.59) for stroke (P=0.034); OR 2.00 (95% CI, 0.81-4.96) among carriers of 1 risk allele, and OR 4.72 (95% CI, 0.62-36.02) for 2 risk alleles. Among noncarriers, smoking was not associated with a stroke.

Conclusions

Current and past smokers who carry APOL1 G1 and/or G2 risk variants may be more susceptible to stroke among the African American population.

Objective

To determine whether early vascular aging may be present in flight attendants with remote in-cabin secondhand smoke (SHS) exposure.

Methods

Twenty-six flight attendants with a history of in-cabin SHS exposure prior to the airline smoking bans were recruited. Pulse wave analysis, peripheral arterial tonometry, and brachial artery reactivity testing evaluated their arterial compliance and endothelial function.

Results

Flight attendants with remote in-cabin SHS exposure have normal blood pressure, pulse wave velocity, and reactive hyperemia index, but abnormal pulse pressure, augmentation index, flow-mediated dilation, and hyperemic mean flow ratio.

Conclusion

These preliminary findings suggest that flight attendants with remote in-cabin SHS exposure have preclinical signs of accelerated vascular aging and raise new questions about the relationship between remote SHS exposure and vascular health.