Publications

OBJECTIVE

Identify gene variants associated with early-onset myocardial infarction (MI).

METHODS AND RESULTS

We tested 11 647 single-nucleotide polymorphisms (SNPs) for association with early-onset MI in a case-control study (study 1 200 cases, 262 controls). To reduce the number of false positives among the 666 SNPs that were nominally associated with early-onset MI (P<0.05) in study 1, we tested these SNPs in study 2 (434 cases, 504 controls). We found that 8 of the 666 SNPs were associated with early-onset MI in study 2 (P<0.05) and had the same risk alleles as in study 1. These 8 SNPs were then tested for association with early-onset MI in study 3 (187 cases, 434 controls). We found that a VAMP8 variant (P = 0.025; odds ratio [OR], 1.75; CI, 1.17 to 2.62) and an HNRPUL1 variant (P = 0.0043; OR, 1.92; CI, 1.28 to 2.86) were associated with early-onset MI (nominal P<0.05; false discovery rate <10%) and had the same risk alleles in all 3 studies.

CONCLUSIONS

Variants in 2 genes were associated with early-onset MI: VAMP8, which is involved in platelet degranulation, and HNRPUL1, which encodes a ribonuclear protein. The identification of these variants could improve understanding of disease mechanisms and suggest novel drug targets.

Evidence is growing that protease-activated receptor-2 (PAR-2) plays a key role in epithelial inflammation. We hypothesized here that PAR-2 plays a central role in epidermal permeability barrier homeostasis by mediating signaling from serine proteases (SP) in the stratum corneum (SC). Since the SC contains tryptic- and chymotryptic-like activity, we assessed the influence of SP activation/inhibition on barrier function. Acute barrier disruption increases SP activity and blockade by topical SP inhibitors (SPI) accelerates barrier recovery after acute abrogation. This improvement in barrier function is due to accelerated lamellar body (LB) secretion. Since tryptic SP signal certain downstream responses through PAR-2, we assessed its potential role in mediating the negative effects of SP on permeability barrier. Firstly, PAR-2 is expressed in the outer nucleated layers of the epidermis and most specifically under basal condition to the lipid raft (LR) domains. Secondly, tape stripping-induced barrier abrogation provokes PAR-2 activation, as shown by receptor internalization (i.e. receptor movement from LR to cytolpasmic domains). Thirdly, topical applications of PAR-2 agonist peptide, SLIGRL, delay permeability barrier recovery and inhibit LB secretion, while, conversely, PAR-2 knockout mice display accelerated barrier recovery kinetics and enhanced LB secretion, paralleled by increased LR formation and caveolin-1 expression. These results demonstrate first, the importance of SP/SPI balance for normal permeability barrier homeostasis, and second, they identify PAR-2 as a novel signaling mechanism of permeability barrier, that is, of response linked to LB secretion.

Lifestyle modifications are first-line therapy for patients with gastroesophageal reflux disease (GERD). We applied an evidence-based approach to determine the efficacy of lifestyle measures for GERD management. We used PubMed and Ovid to perform a search of the literature published between 1975 and 2004 using the key words heartburn, GERD, smoking, alcohol, obesity, weight loss, caffeine or coffee, citrus, chocolate, spicy food, head of bed elevation, and late-evening meal. Each study was reviewed by 2 reviewers who assigned one of the following ratings: evidence A, randomized clinical trials; evidence B, cohort or case-control studies; evidence C, case reports or flawed clinical trials; evidence D, investigator experience; or evidence E, insufficient information. We screened 2039 studies and identified 100 that were relevant. Only 16 clinical trials examined the impact on GERD (by change in symptoms, esophageal pH variables, or lower esophageal sphincter pressure) of the lifestyle measure. Although there was physiologic evidence that exposure to tobacco, alcohol, chocolate, and high-fat meals decreases lower esophageal sphincter pressure, there was no published evidence of the efficacy of dietary measures. Neither tobacco nor alcohol cessation was associated with improvement in esophageal pH profiles or symptoms (evidence B). Head of bed elevation and left lateral decubitus position improved the overall time that the esophageal pH was less than 4.0 (evidence B). Weight loss improved pH profiles and symptoms (evidence B). Weight loss and head of bed elevation are effective lifestyle interventions for GERD. There is no evidence supporting an improvement in GERD measures after cessation of tobacco, alcohol, or other dietary interventions.