The moderation of adolescent-to-peer similarity in tobacco and alcohol use by school levels of substance use

Using the National Longitudinal Study of Adolescent Health, this study examined the impact of school-level smoking and drinking on adolescent-peer similarity for smoking and drinking. Hierarchical linear modeling revealed that adolescent-peer similarity was significantly moderated by school-level substance use for both tobacco and alcohol use. For tobacco, similarity between adolescent and peer use increased from .18 in the lower quartile of tobacco-using schools to .44 in the upper quartile of tobacco-using schools. Corresponding similarities for alcohol use ranged from .25 to .34. These results suggest that schools with relatively few substance-using peers provide less opportunities for adolescents to pick niches that expose them to risk factors that correspond to their own substance-use behaviors.     

Extending Previous cG×I Findings on 5‐HTTLPR's Moderation of Intervention Effects on Adolescent Substance Misuse Initiation

This study addresses replication in candidate gene × environment interaction (cG×E) research by investigating if the key findings from Brody, Beach, Philibert, Chen, and Murry (2009) can be detected using data (N = 1,809) from the PROSPER substance use preventive intervention delivery system. Parallel to Brody et al., this study tested the hypotheses that substance misuse initiation would increase faster from age 11 to age 14 and be higher at age 14 among: (a) 5‐HTTLPR short carrier adolescents versus long homozygotes, (b) control versus intervention adolescents, and (c) 5‐HTTLPR short carriers in the control condition versus all other participants. The hypotheses were generally supported and results were consistent with Brody et al.'s cG×I finding. Results are discussed in light of replication issues in cG×E research and implications for intervention.     

Beneficial effect of enriched air nitrox on bubble formation during scuba diving. An open-water study

Bubble formation during scuba diving might induce decompression sickness.

This prospective randomised and double-blind study included 108 advanced recreational divers (38 females). Fifty-four pairs of divers, 1 breathing air and the other breathing nitrox28 undertook a standardised dive (24 ± 1 msw; 62 ± 5min) in the Red Sea. Venous gas bubbles were counted (Doppler) 30–<45 min (early) and 45–60 min (late) post-dive at jugular, subclavian and femoral sites.

Only 7% (air) vs. 11% (air28®) (n.s.) were bubble-free after a dive. Independent of sampling time and breathing gas, there were more bubbles in the jugular than in the femoral vein. More bubbles were counted in the air-group than in the air28-group (pooled vein: early: 1845 vs. 948; P = 0.047, late: 1817 vs. 953; P = 0.088). The number of bubbles was sex-dependent. Lastly, 29% of female air divers but only 14% of male divers were bubble-free (P = 0.058).

Air28® helps to reduce venous gas emboli in recreational divers. The bubble number depended on the breathing gas, sampling site and sex. Thus, both exact reporting the dive and in particular standardising sampling characteristics seem mandatory to compare results from different studies to further investigate the hitherto incoherent relation between inert gas bubbles and DCS.