Suzanne M. Dostaler

Cross-national Study of Fighting and Weapon Carrying as Determinants of Adolescent Injury

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 161082 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. Conclusions. Fighting and weapon carrying are 2 common indicators of physical violence that are experienced by young people. Associations of fighting and weapon carrying with injury-related health outcomes are remarkably similar across countries. Violence is an important issue affecting the health of adolescents internationally.

Stages of development and injury patterns in the early years: a population-based analysis

BackgroundIn 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.MethodsFour complete years of data (1999–2002; n = 5876 cases) were reviewed from the Kingston sites of the Canadian Hospitals Injury Reporting and Prevention Program (CHIRPP), an ongoing injury surveillance initiative. Epidemiological analyses were used to characterize injury patterns within and across age groups (0–6 years) that corresponded to normative developmental stages.ResultsThe average annual rate of emergency department-attended childhood injury was 107 per 1000 (95% CI 91–123), with boys experiencing higher annual rates of injury than girls (122 vs. 91 per 1000; p < 0.05). External causes of injury changed substantially by developmental stage. This lead to the identification of four prevention priorities surrounding 1) the optimization of supervision; 2) limiting access to hazards; 3) protection from heights; and 4) anticipation of risks.ConclusionThis population-based injury surveillance analysis provides a strong evidence-base to inform and enhance anticipatory counseling and other public health efforts aimed at the prevention of childhood injury during the early years.

RECIPROCAL MODULATION OF TRKA AND P75NTR AFFINITY STATES IS MEDIATED BY DIRECT RECEPTOR INTERACTIONS

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.

A Randomized Controlled Trial of an Educational Intervention to Prevent the Chronic Pain of Whiplash Associated Disorders Following Rear-End Motor Vehicle Collisions

Study Design. Concealed allocation, multicenter, single-blind, randomized controlled clinical trial. Objective. To assess the efficacy of an educational video in the tertiary prevention of persistent WAD symptoms following rear-end motor vehicle collisions (MVCs). Summary of Background Data. Whiplash-associated disorders (WAD) are an important and costly health problem. There is a lack of high quality evidence surrounding efficacy of treatments for WAD. Existing research supports active interventions and early return to regular activities. Methods. Consecutive patients presenting to four tertiary care emergency departments following rear-end MVCs were eligible. Following informed consent, patients were allocated, using central randomization, to receive an educational video plus usual care or usual care alone. The video provided reassurance, and advice about posture, return to regular activities, exercises, and pain-relief methods. Data were collected by telephone using standardized questionnaires. The primary outcome was presence of Persistent WAD Symptoms at 24 weeks postinjury, based on the frequency and severity of neck, shoulder, or upper back pain. The absolute difference in proportion of patients with persistent WAD symptoms and rate ratios were calculated. Changes in pain scores were compared using the Mann-Whitney U test. Results. The intervention (n = 206) and control (n = 199) groups were similar at baseline (mean age 38.4 years; 64% female). Overall, the proportion of subjects with Persistent WAD Symptoms decreased from 89.1% at baseline to 33.6% at 24 weeks after injury. At 24 weeks, the proportion of subjects with persistent WAD symptoms in the intervention group was 7.9% (95% CI, −2.0, 17.8) lower than the control group. The median improvement in pain score at 24 weeks was 3 for the intervention group and 2 for the control group (P = 0.016). Conclusion. 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.

Associations between risk behavior and injury and the protective roles of social environments: an analysis of 7235 Canadian school children

Objective: The social etiology of adolescent injury remains poorly understood. The Population Health Framework suggests that the etiology of adolescent injury involves interactions between individual risk factors and the natures of adolescent environments. The purpose of this study was to apply this framework to examination of relationships between adolescent risk taking and injury, and the potential modifying effects of supportive home and school environments. Methods: The analysis was conducted in a representative sample of 7235 males and females (10–16 years old) from Canada. Results were based on records from the 2001/02 World Health Organization Health Behaviour in School-Aged Children Survey. Individual items and factor analytically derived scales were used to describe and then model injury outcomes, risk behaviors, perceived home, and school climates, and the relationships between these variables in a theory driven etiological analysis. Results: Adolescents with supportive home and school environments experienced lower relative odds of engagement in risk taking behavior and lower relative odds of injury. Gradients were observed between the extent of adolescent risk taking and the occurrence of injury. Interactions were not observed between risk taking behavior, perceived support in home and school climates, and injury. Conclusions: Risk taking is common among adolescents and plays a role in the etiology of injury. Supportive social climates clearly protect adolescents from engaging in these behaviors, and also the occurrence of some forms of injury. However, once an adolescent chooses to engage in risk taking behaviour, a supportive environment may not protect them from injury.

Influence of Multiple Risk Behaviors on Physical Activity–Related Injuries in Adolescents

OBJECTIVE. The study objectives were to (1) examine the relationship between physical activity and physical activity injuries in youth, (2) determine whether this relationship is modified by the engagement in multiple risk behaviors, and (3) determine whether this relationship is modified by the setting of the injury (school versus outside of school). METHODS. We examined associations between physical activity and multiple risk behaviors with physical activity injuries occurring at and outside of school. The study population consisted of a representative sample of 5559 Canadian youth in grades 6 through 10 who participated in the 2001/2002 Health Behavior in School-Aged Children Survey. The exposure and outcome measures were determined from a classroom-based survey. RESULTS. Irrespective of grade, there were strong gradient relations between physical activity participation and related injuries outside of school. Conversely, there were modest relations between physical activity participation and related injuries at school. In students in grades 6 to 8, there was no relation between multiple risk behaviors and physical activity injuries at school and a curvilinear relation between multiple risk behaviors and physical activity injuries outside of school. The opposite pattern of relationships between multiple risk behaviors and injuries was observed in students in grades 9 to 10. Irrespective of grade and setting of injury, there was no significant interaction between physical activity and multiple risk behaviors on injury risk. The results were consistent by severity of injury and for structured/organized and unstructured/informal forms of physical activity. CONCLUSIONS. 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.

The binding of zinc and copper ions to nerve growth factor is differentially affected by pH: implications for cerebral acidosis

It has recently been shown that transition metal cations Zn2+ and Cu2+ bind to histidine residues of nerve growth factor (NGF) and other neurotrophins (a family of proteins important for neuronal survival) leading to their inactivation. Experimental data and theoretical considerations indicate that transition metal cations may destabilize the ionic form of histidine residues within proteins, thereby decreasing their pKa values. Because the release of transition metal cations and acidification of the local environment represent important events associated with brain injury, the ability of Zn2+ and Cu2+ to bind to neurotrophins in acidic conditions may alter neuronal death following stroke or as a result of traumatic injury. To test the hypothesis that metal ion binding to neurotrophins is influenced by pH, the effects of Zn2+ and Cu2+ on NGF conformation, receptor binding and NGF tyrosine kinase (trkA) receptor signal transduction were examined under conditions mimicking cerebral acidosis (pH range 5.5–7.4). The inhibitory effect of Zn2+ on biological activities of NGF is lost under acidic conditions. Conversely, the binding of Cu2+ to NGF is relatively independent of pH changes within the studied range. These data demonstrate that Cu2+ has greater binding affinity to NGF than Zn2+ at reduced pH, consistent with the higher affinity of Cu2+ for histidine residues. These findings suggest that cerebral acidosis associated with stroke or traumatic brain injury could neutralize the Zn2+‐mediated inactivation of NGF, whereas corresponding pH changes would have little or no influence on the inhibitory effects of Cu2+. The importance of His84 of NGF for transition metal cation binding is demonstrated, confirming the involvement of this residue in metal ion coordination.

Comparison of Asthma Control Criteria: Importance of Spirometry

Aims. To compare the measurements of asthma control using Canadian Thoracic Society (CTS) Asthma Management Consensus Summary and Global Initiative for Asthma (GINA) guidelines composite indices with and without spirometry. Methods. Asthma control parameters were extracted from electronic medical records (EMRs) of patients ≥6 years old at two primary care sites. Asthma control ratings calculated according to CTS and GINA criteria were compared. Results. Data were available from 113 visits by 93 patients, aged 6–85 years (38.7 ± 24.8; mean ± SD). The proportion of visits at which individuals’ asthma was completely controlled was 22.1% for CTS symptoms only and 9.7% for CTS with spirometry (p < .01); and 17.7% versus 14.1% for GINA symptoms only versus symptoms with spirometry (p = .125). Conclusions. Asthma control ratings using GINA and CTS criteria are discordant in more than half of the patients deemed “in control” by at least one scale. Differences in the spirometry criterion threshold are primarily responsible for this discordance. Failure to include spirometry as part of the control index consistently overestimates asthma control and may underestimate future risk of exacerbations.

Characterization of a Distinctive Motif of the Low Molecular Weight Neurotrophin Receptor that Modulates NGF-mediated Neurite Growth

The cytoplasmic region of the common neurotrophin receptor (p75NGFR) (rat, human, chick) contains a putative membrane‐associating domain implicated in intracellular signalling. A peptide (R3) identical to this domain (p75NGFR 367–379) and various analogues of this peptide displayed circular dichroism spectra in aqueous and non‐polar environments identical to the amphiphilic tetradecapeptide mastoparan (MP) and were internalized by PC12 rat pheochromocytoma cells. The R3 peptide enhanced neurite growth in PC12 cells, embryo chick primary sensory neurons and fetal rat primary sensory neurons in vitro in the presence of sub‐saturating concentrations of NGF. Peptide analogues of R3 not faithful to the distance and angular relationships of ionic groups and the putative amphiphilic structure of p75NGFR 367–379 displayed reduced potency to enhance NGF‐mediated neurite growth. Exposure of NGF and the R3 peptide to a cell line displaying predominantly p75NGFR (PC12nnr5), had no influence on neurite growth. The R3 peptide had no effects on cell survival, cell binding or uptake of [125I]NGF, affinity cross‐linking of [125I]NGF to p75NGFR or trkA monomers and homodimers, or NGF‐mediated trkA monomer tyrosine phosphorylation. The studies implicate a role for a highly conserved motif of p75NGFR in the downstream modulation of NGF‐mediated neurite growth.

Impact of a rapid access protocol on decreasing door-to-balloon time in acute ST elevation myocardial infarction

OBJECTIVE Ischemic cardiovascular disease is the leading cause of death in Canada. In ST elevation myocardial infarction (STEMI), time to reperfusion is a key determinant in reducing morbidity and mortality with percutaneous coronary intervention (PCI) being the preferred reperfusion strategy. Where PCI is available, delays to definitive care include times to electrocardiogram (ECG) diagnosis and cardiovascular laboratory access. In 2004, the Cardiac Care Network of Ontario recommended implementation of an emergency department (ED) protocol to reduce reperfusion time by transporting patients with STEMI directly to the nearest catheterization laboratory. The model was implemented in Frontenac County in April 2005. The objective of this study was to assess the effectiveness of a protocol for rapid access to PCI in reducing door-to-balloon times in STEMI. METHODS Two 1-year periods before and after implementation of a rapid access to PCI protocol (ending March 2005 and June 2006, respectively) were studied. Administrative databases were used to identify all subjects with STEMI who were transported by regional emergency medical services (EMS) and received emergent PCI. The primary outcome measure was time from ED arrival to first balloon inflation (door-to-balloon time). Times are presented as medians and interquartile ranges (IQRs). Statistical comparisons were made using the Mann-Whitney U test and presented graphically with Kaplan-Meier curves. RESULTS Patients transported under the rapid access protocol (n = 39) were compared with historical controls (n = 42). Median door-to-balloon time was reduced from 87 minutes (IQR 67-108) preprotocol to 62 minutes (IQR 40-80) postprotocol (p < 0.001). CONCLUSION In our region, implementation of an EMS protocol for rapid access to PCI significantly reduced time to reperfusion for patients with STEMI.