Objectives-(1) To compare the prevalence of bullying and victimization among boys and girls and by age in 40 countries. (2) In 6 countries, to compare rates of direct physical, direct verbal, and indirect bullying by gender, age, and country.Methods-Cross-sectional self-report surveys including items on bullying and being bullied were obtained from nationally representative samples of 11, 13 and 15 year old school children in 40 countries, N = 202,056. Six countries (N = 29,127 students) included questions about specific types of bullying (e. g., direct physical, direct verbal, indirect).Results-Exposure to bullying varied across countries, with estimates ranging from 8.6 % to 45.2 % among boys, and from 4.8 % to 35.8 % among girls. Adolescents in Baltic countries reported higher rates of bullying and victimization, whereas northern European countries reported the lowest prevalence. Boys reported higher rates of bullying in all countries. Rates of victimization were higher for girls in 29 of 40 countries. Rates of victimization decreased by age in 30 of 40 (boys) and 25 of 39 (girls) countries.Conclusion-There are lessons to be learned from the current research conducted in countries where the prevalence is low that could be adapted for use in countries with higher prevalence.

ABSTRACT. Objectives. We sought to (1) compare estimates of the prevalence of fighting and weapon carrying among adolescent boys and girls in North American and European countries and (2) assess in adolescents from a subgroup of these countries comparative rates of weapon carrying and characteristics of fighting and injury outcomes, with a determination of the association between these indicators of violence and the occurrence of medically treated injury.Design and Setting. Cross-sectional self-report surveys using 120 questions were obtained from nationally representative samples of 161 082 students in 35 countries. In addition, optional factors were assessed within individual countries: characteristics of fighting (9 countries); characteristics of weapon carrying (7 countries); and medically treated injury (8 countries).Participants. Participants included all consenting students in sampled classrooms (average age: 11-15 years).Measures. The primary measures assessed included involvement in physical fights and the types of people involved; frequency and types of weapon carrying; and frequency and types of medically treated injury.Results. Involvement in fighting varied across countries, ranging from 37% to 69% of the boys and 13% to 32% of the girls. Adolescents most often reported fighting with friends or relatives. Among adolescents reporting fights, fighting with total strangers varied from 16% to 53% of the boys and 5% to 16% of the girls. Involvement in weapon carrying ranged from 10% to 21% of the boys and 2% to 5% of the girls. Among youth reporting weapon carrying, those carrying handguns or other firearms ranged from 7% to 22% of the boys and 3% to 11% of the girls. In nearly all reporting countries, both physical fighting and weapon carrying were significantly associated with elevated risks for medically treated, multiple, and hospitalized injury events. 11 Results from these studies have broadened our knowledge of the global impact that adolescent violence has on public health. Existing international comparisons of youth violence have focused on the frequency of adolescent violence-related behaviors in a small number of countries, 12 comparisons of episodes of school violence and its determinants in Israeli and Arabic student populations, 13 studies of "child soldiers" in countries engaged in civil and international warfare, 14,15 international comparisons of firearmrelated mortality, 3 and, as part of more general international comparisons, examinations of firearm regulations and rates of homicide, 3,16,17 robberies and sexual assaults, 17,18 and suicide. 16 Beyond studies of firearms, international comparisons of rates of youth violence are still lacking, and the magnitude and nature of the adolescent violence problem remains unknown for many countries. Cross-national comparisons of violent behaviors in youth have been problematic, because of the use of nonrepresentative samples in many countries and a lack of uniformity in study designs. ConclusionsPhysical fighting and engagement in weapon carry...

A role for Zn2+ in a variety of neurological conditions such as stroke, epilepsy and Alzheimer's disease has been postulated. In many instances, susceptible neurons are located in regions rich in Zn2+ where nerve growth factor (NGF) levels rise as a result of insult. Although the interaction of Zn2+ with this neurotrophin has previously been suggested, the direct actions of the ion on NGF function have not been explored. Molecular modeling studies predict that Zn2+ binding to NGF will induce structural changes within domains of this neurotrophin that participate in the recognition of TrkA and p75NTR. We demonstrate here that Zn2+ alters the conformation of NGF, rendering it unable to bind to p75NTR or TrkA receptors or to activate signal transduction pathways and biological outcomes normally induced by this protein. Similar actions of Zn2+ are also observed with other members of the NGF family, suggesting a modulatory role for this metal ion in neurotrophin function.

Background: In Canada, there are many formal public health programs under development that aim to prevent injuries in the early years (e.g. 0-6). There are paradoxically no population-based studies that have examined patterns of injury by developmental stage among these young children. This represents a gap in the Canadian biomedical literature. The current population-based analysis explores external causes and consequences of injuries experienced by young children who present to the emergency department for assessment and treatment. This provides objective evidence about prevention priorities to be considered in anticipatory counseling and public health planning.

Equilibrium binding of 125I-nerve growth factor (125I-NGF) to cells coexpressing the tyrosine kinase receptor A (TrkA) and common neurotrophin receptor (p75NTR), cells coexpressing both receptors where p75NTR is occupied, and cells expressing only p75NTR, revealed reciprocal modulation of receptor affinity states. Analysis of receptor affinity states in PC12 cells, PC12 cells in the presence of brain-derived neurotrophic factor (BDNF), and PC12nnr5 cells suggested that liganded and unliganded p75NTR induce a higher affinity state within TrkA, while TrkA induces a lower affinity state within p75NTR. These data are consistent with receptor allosterism, and prompted a search for TrkA/p75NTR complexes in the absence of NGF. Chemical crosslinking studies revealed high molecular weight receptor complexes that specifically bound 125I-NGF, and were immunoprecipitated by antibodies to both receptors. The heteroreceptor complex of TrkA and p75NTR alters conformation and/or dissociates in the presence of NGF, as indicated by the ability of low concentrations of NGF to prevent heteroreceptor crosslinking. These data suggest a new model of receptor interaction, whereby structural changes within a heteroreceptor complex are induced by ligand binding.

The presence of persistent WAD symptoms following simple rear-end MVCs was high in this sample. The video group demonstrated a trend toward less severe WAD symptoms. We recommend evaluating other educational interventions that could reduce WAD symptoms.

The environment moderated the relation between physical activity and related injuries in that strong risk gradients only existed outside of the school setting. Unexpectedly, there were no consistent gradients between the engagement in multiple risk behaviors and physical activity injuries or any interaction effect between physical activity exposure and multiple risk behaviors. These findings suggest that optimizing the environment would be a preferred strategy for preventing physical activity injuries compared with selectively targeting youth who engage in multiple risk behaviors.

Background-Physical aggression is an important issue in North American populations. The importance of student social environments in the occurrence of physical aggression requires focused study. In this study, reports of physical aggression were examined in relation to social environment factors among national samples of students from Canada and the United States.