Publications

The functional consequences of genetic variation in mammalian regulatory elements are poorly understood. We report the in vivo dissection of three mammalian enhancers at single-nucleotide resolution through a massively parallel reporter assay. For each enhancer, we synthesized a library of >100,000 mutant haplotypes with 2-3% divergence from the wild-type sequence. Each haplotype was linked to a unique sequence tag embedded within a transcriptional cassette. We introduced each enhancer library into mouse liver and measured the relative activities of individual haplotypes en masse by sequencing the transcribed tags. Linear regression analysis yielded highly reproducible estimates of the effect of every possible single-nucleotide change on enhancer activity. The functional consequence of most mutations was modest, with ∼22% affecting activity by >1.2-fold and ∼3% by >2-fold. Several, but not all, positions with higher effects showed evidence for purifying selection, or co-localized with known liver-associated transcription factor binding sites, demonstrating the value of empirical high-resolution functional analysis.

Cell adhesion molecules govern leukocyte-endothelial cell (EC) interactions that are essential in regulating leukocyte recruitment, adhesion, and transmigration in areas of inflammation. In this paper, we synthesized hydrogel matrices modified with antibodies against vascular cell adhesion molecule-1 (VCAM1) and endothelial leukocyte adhesion molecule-1 (E-Selectin) to mimic leukocyte-EC interactions. Adhesion of human umbilical vein ECs to polyvinyl alcohol (PVA) hydrogels was examined as a function of the relative antibody ratio (anti-VCAM1:anti-E-Selectin) and substrate elasticity. Variation of PVA backbone methacrylation was used to affect hydrogel matrix stiffness, ranging from 130 to 720 kPa. Greater EC adhesion was observed on hydrogels presenting 1:1 anti-VCAM1:anti-E-Selectin than on gels presenting either arginine-glycine-asparagine (RGD) peptide, anti-VCAM1, or anti-E-Selectin alone. Engineered cell adhesion - based on complementing the EC surface presentation - may be used to increase the strength of EC-matrix interactions. Hydrogels with tunable and synergistic adhesion may be useful in vascular remodeling.

INTRODUCTION

Psychosocial stress is a significant risk factor for smoking, and Blacks experience higher levels of psychosocial stress relative to other racial/ethnic groups. Limited research has comprehensively examined psychosocial stressors in relation to smoking among Blacks.

METHODS

We examined psychosocial stressors in relation to smoking status (current, previous, and never) in middle-aged Blacks (34-85 years, n = 592) from Milwaukee, Wisconsin, a subset of the Midlife in the United States Study II (2004-2006). Eleven stressor domains were assessed, including psychological and physical work stress, work-family conflict, perceived inequality, relationship stress, neighborhood stress, discrimination, financial stress, recent problems, stressful events, and childhood adversity. We also calculated a cumulative score. Multinomial models were adjusted for age, gender, education, and income.

RESULTS

Seven of the 11 stressors and the cumulative score were associated with higher odds of being a current smoker compared with a never-smoker: neighborhood, financial, relationship, and psychological work stress, perceived inequality, stressful events, childhood adversity (p values <.05; ORs ranged from 1.28 to 1.77). Three stressors and the cumulative score were associated with higher odds of being a previous smoker versus a never-smoker (p < .05). Individuals who scored in the top quartile on 5 or more stressors were 3.74 (95% CI = 2.09-6.71) times as likely to be current smokers, and more than twice as likely to be previous smokers, compared with individuals with no high stressors.

CONCLUSIONS

These results demonstrate a strong relationship between stress and smoking among urban middle-aged Blacks and suggest that cessation programs should address modifiable individual and community-level stressors.

Atrial fibrillation is the commonest arrhythmia worldwide and is a growing problem. AF is responsible for 25% of all strokes, and these patients suffer greater mortality and disability. Warfarin has traditionally been the only successful therapy for stroke prevention, but its limitations have resulted in underutilisation. Major progress has been made in AF research, leading to improved management strategies. Better risk stratification permits identification of truly low-risk patients who do not require anticoagulation and we are able to simplify ourevaluation of a patient's bleeding risk.The advent of novel anticoagulants means warfarin is no longer the only choice for stroke prophylaxis. These drugs circumvent many of warfarin's inconveniences, but onlylong-term study and use will conclusively demonstrate how they compare to warfarin. The landscape of stroke prevention in AF has changed with effective alternatives to warfarin available for the first time in 60 years-but each new option brings new considerations.