A Systematic Review of Family Meal Frequency and Risk Taking Behaviors in Adolescence

poster abstractThe purpose of this systematic review is to examine the association between adolescent health behaviors (alcohol use, cigarette smoking and marijuana use) and family meal routines. Following the guidelines of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses by Mosher and colleagues, the search was conducted using select databases (CINAHL, Medline, PSYCHINFO, and Social Science Index). Keywords were family meals and adolescence. The search parameters were set to include adolescent’s ages 9-18, English language and journal articles only. The preliminary search generated 169 articles and one article was added from the reference lists. A total of 11 articles met the criteria for the review after 159 articles were excluded due to duplication and initial review. Three of seven studies that examined the relationship between tobacco use and family meals found an inverse relationship between the two for both male and females. Seven articles examined family meal frequency and marijuana use. Four of those articles found an association between an increased frequency of meals and a decreased use of marijuana in females but not males. Three of seven articles found an inverse relationship between alcohol use and family meal routines. Family meals appear to be a protective factor for adolescent risky health behaviors, however, more research is needed to examine the quality and quantity of family meals. The “dosage” would be important in developing guidelines for education and intervening with families

DNA Methylation of the First Exon Is Tightly Linked to Transcriptional Silencing

Tissue specific patterns of methylated cytosine residues vary with age, can be altered by environmental factors, and are often abnormal in human disease yet the cellular consequences of DNA methylation are incompletely understood. Although the bodies of highly expressed genes are often extensively methylated in plants, the relationship between intragenic methylation and expression is less clear in mammalian cells. We performed genome-wide analyses of DNA methylation and gene expression to determine how the pattern of intragenic methylation correlates with transcription and to assess the relationship between methylation of exonic and intronic portions of the gene body. We found that dense exonic methylation is far more common than previously recognized or expected statistically, yet first exons are relatively spared compared to more downstream exons and introns. Dense methylation surrounding the transcription start site (TSS) is uncoupled from methylation within more downstream regions suggesting that there are at least two classes of intragenic methylation. Whereas methylation surrounding the TSS is tightly linked to transcriptional silencing, methylation of more downstream regions is unassociated with the magnitude of gene expression. Notably, we found that DNA methylation downstream of the TSS, in the region of the first exon, is much more tightly linked to transcriptional silencing than is methylation in the upstream promoter region. These data provide direct evidence that DNA methylation is interpreted dissimilarly in different regions of the gene body and suggest that first exon methylation blocks transcript initiation, or vice versa. Our data also show that once initiated, downstream methylation is not a significant impediment to polymerase extension. Thus, the consequences of most intragenic DNA methylation must extend beyond the modulation of transcription magnitude

Combined Forward-Backward Asymmetry Measurements in Top-Antitop Quark Production at the Tevatron

The CDF and D0 experiments at the Fermilab Tevatron have measured the asymmetry between yields of forward- and backward-produced top and antitop quarks based on their rapidity difference and the asymmetry between their decay leptons. These measurements use the full data sets collected in proton-antiproton collisions at a center-of-mass energy of $\sqrt s =1.96$ TeV. We report the results of combinations of the inclusive asymmetries and their differential dependencies on relevant kinematic quantities. The combined inclusive asymmetry is $A_{\mathrm{FB}}^{t\bar{t}} = 0.128 \pm 0.025$. The combined inclusive and differential asymmetries are consistent with recent standard model predictions