Background Social media (SM) use is increasing among U.S. young adults, and its association with mental well-being remains unclear. This study assessed the association between SM use and depression in a nationally-representative sample of young adults. Methods We surveyed 1,787 adults ages 19 to 32 about SM use and depression. Participants were recruited via random digit dialing and address-based sampling. SM use was assessed by self-reported total time per day spent on SM, visits per week, and a global frequency score based on the Pew Internet Research Questionnaire. Depression was assessed using the Patient-Reported Outcomes Measurement Information System (PROMIS) Depression Scale Short Form. Chi-squared tests and ordered logistic regressions were performed with sample weights. Results The weighted sample was 50.3% female and 57.5% White. Compared to those in the lowest quartile of total time per day spent on SM, participants in the highest quartile had significantly increased odds of depression (AOR=1.66, 95% CI=1.14–2.42) after controlling for all covariates. Compared with those in the lowest quartile, individuals in the highest quartiles of SM site visits per week and those with a higher global frequency score had significantly increased odds of depression (AOR=2.74, 95% CI=1.86–4.04; AOR=3.05, 95% CI=2.03–4.59, respectively). All associations between independent variables and depression had strong, linear, dose-response trends. Results were robust to all sensitivity analyses. Conclusions SM use was significantly associated with increased depression. Given the proliferation of SM, identifying the mechanisms and direction of this association is critical for informing interventions that address SM use and depression.

Background: Due in part to declining vaccination rates, in 2018 over 20 states reported at least one case of measles, and over 40,000 cases have been confirmed in Europe. Antivaccine posts on social media may be facilitating anti-vaccination behaviour. This study aimed to systematically characterize (1) individuals known to publicly post antivaccination content on Facebook, (2) the information they convey, and (3) the spread of this content. Methods: Our data set consisted of 197 individuals who posted anti-vaccination comments in response to a message promoting vaccination. We systematically analysed publicly-available content using quantitative coding, descriptive analysis, social network analysis, and an in-depth qualitative assessment. The final codebook consisted of 26 codes; Cohen's κ ranged 0.71-1.0 after double-coding. Results: The majority (89%) of individuals identified as female. Among 136 individuals who divulged their location, 36 states and 8 other countries were represented. In a 2mode network of individuals and topics, modularity analysis revealed 4 distinct subgroups labelled as "trust," "alternatives," "safety," and "conspiracy." For example, a comment representative of "conspiracy" is that poliovirus does not exist and that pesticides caused clinical symptoms of polio. An example from the "alternatives" subgroup is that eating yogurt cures human papillomavirus. Deeper qualitative analysis of all 197 individuals' profiles found that these individuals also tended to post material against other health-related practices such as water fluoridation and circumcision.

Background Although the etiology of eating concerns is multi-factorial, exposure to media messages is considered to be a contributor. While traditional media, such as television and magazines, have been examined extensively in relation to eating concerns risk, the influence of social media has received relatively less attention. Objective To examine the association between social media use and eating concerns in a large, nationally representative sample of young adults. Design Cross-sectional survey. Participants/setting Participants were 1765 young adults ages 19-32 years, who were randomly selected from a national probability-based online non-volunteer panel. Outcome measures An eating concerns scale was adapted from two validated measures: the SCOFF Questionnaire and the Eating Disorder Screen for Primary Care (ESP). Social media use (including Facebook, Twitter, Google+, YouTube, LinkedIn, Instagram, Pinterest, Tumblr, Vine, Snapchat, and Reddit) was assessed using both volume (time per day) and frequency (visits per week). Statistical analyses To examine associations between eating concerns and social media use, ordered logistic regression was used, controlling for all covariates. Results Compared to those in the lowest quartile, participants in the highest quartiles for social media volume and frequency had significantly greater odds of having eating concerns (adjusted odds ratio [AOR] = 2.18, 95% CI = 1.50 - 3.17 and AOR = 2.55, 95% CI = 1.72 - 3.78, respectively). There were significant positive overall linear associations between the social media use variables and eating concerns (P < 0.001). Conclusions The results from this study indicate a strong and consistent association between social media use and eating concerns in a nationally-representative sample of young adults ages 19 to 32 years. This association was apparent whether social media use was measured as volume or frequency. Further research should assess the temporality of these associations. It would also be useful to examine more closely the influence of specific characteristics of social media use—including content-related and contextual features.

Baseline e-cigarette use was independently associated with initiation of traditional cigarette smoking at 18 months. This finding supports policy and educational interventions designed to decrease use of e-cigarettes among nonsmokers.

Background & Aims NK1.1+ TCRαβint CD1-restricted T (NKT) cells are a unique subset of T lymphocytes that are thought to have an immunoregulatory role in a wide range of diseases. Most mouse NKT cells express a T-cell receptor that contains an invariant Vα14Jα18 chain and recognizes antigenic glycolipids presented in association with MHC class Ib (CD1d) molecules. These invariant NKT cells (iNKT) have been implicated in cholestatic liver injury. Methods We examined the role of iNKT cells in liver injury associated with biliary obstruction in mice with ligations of the common bile duct. Results The number of activated iNKT cells increased markedly in the livers of mice following bile duct-ligation (BDL). Plasma alanine aminotransferase (ALT) levels, an indicator of liver injury, were significantly higher in iNKT cell–deficient (Jα18−/−) mice, compared to wild-type mice, following BDL. Photoimage analysis of histologic sections confirmed that more damage was present in the livers of in Jα18−/−mice; liver damage correlated with increases in keratinocyte-derived chemokine (KC) and macrophage inflammatory protein-2 (MIP-2) production as well as neutrophil sequestration. Liver injury was significantly reduced in Jα18−/−mice treated with anti-KC and anti-MIP-2 or rendered neutrophil-deficient before BDL. Similarly, Jα18−/−mice that were injected with iNKT cells before BDL exhibited significant decreases in neutrophil accumulation and liver damage. Conclusion These data document the role of iNKT cells in suppressing the neutrophil proinflammatory response and neutrophil-dependent cholestatic liver damage.