School Violence Among a Nationally Representative Sample of Adolescents in Chile.

Background: School violence is widely acknowledged as a public health problem with considerable consequences on student learning and social development. There are also a wide range of health consequences. A large share of previous research on school violence has focused on populations in the global north, with significant gaps in the state of knowledge in the world's emerging economies. To this end, the present study provides an examination of correlates for school-based violence in Chile using a nationally representative cohort. Methods: Six independent variables were considered (age, sex, physical activity, sedentary life style, bullying victimization, food insecurity) within a logistic regression model to ascertain the strength and direction of associations with physical fighting. Results: Among the surveyed students, ~13.08% reported being involved in two or more physical fights during the twelve month recall period. Males were significantly over represented among those reporting being involved in a fight OR 2.91 (CI = 1.98-4.27). Those who reported experiencing food insecurity were 5.29 (CI = 1.43-19.50) times more likely to have been involved in a physical fight. Students who reported being bullied were 2.41 (CI = 1.67-3.47) times more likely to have been involved in physical fights. While age provided protection from involvement in physical fights with an adjusted odds ratio of 0.91 (CI = 0.84-0.98). Conclusion: Consistent with previous research, our results suggest that the use of school-based interventions that target multiple risk behaviors may be helpful in reducing rates of physical fighting.

Tear lacritin levels by age, sex, and time of day in healthy adults.

PURPOSE: Several small proteomic studies suggest that the prosecretory tear protein lacritin may be selectively downregulated in dry eye syndrome and in blepharitis, yet little information is available about normal baseline levels. This study assessed lacritin levels in tears from healthy individuals and addressed whether they differ according to sex, age, or time of day. METHODS: Rabbit antibodies against lacritin N-terminal peptide EDASSDSTGADPAQEAGTS (Pep Lac N-Term) were generated and characterized against human recombinant lacritin and N-65 truncation mutant. Basal tears were collected from 66 healthy individuals ranging in age from 18 to 52 years, and at four times during one 24-hour period from 34 other individuals. Lacritin levels were then analyzed by ELISA and Western blotting. RESULTS: Anti-Pep Lac N-Term bound lacritin, but not truncation mutant N-65 that lacks the N-terminal antigenic site. Tear lacritin levels followed a normal distribution with a mean of 4.2 ± 1.17 ng/100 ng total tear protein. Levels differed little by age or sex, and decreased slightly between 4 and 8 hours in a 24-hour cycle. Tear-blocking effects were minimal, as suggested by spiking of tears with recombinant lacritin. CONCLUSIONS: Anti-Pep Lac N-Term-detectable lacritin comprises ~4.2 ng/100 ng total tear protein in healthy individuals, with no significant differences between males and females or among individuals between 18 and 52 years old. Levels decrease slightly in the late afternoon. These findings provide a baseline for future immunodiagnostic studies of lacritin in dry eye and other ocular diseases.