The Canadian Healthy Infant Longitudinal Development (CHILD) Study: examining developmental origins of allergy and asthma.

The Canadian Healthy Infant Longitudinal Development (CHILD) birth cohort study recruited 3624 pregnant women, most partners and 3542 eligible offspring. We hypothesise that early life physical and psychosocial environments, immunological, physiological, nutritional, hormonal and metabolic influences interact with genetics influencing allergic diseases, including asthma. Environmental and biological sampling, innate and adaptive immune responses, gene expression, DNA methylation, gut microbiome and nutrition studies complement repeated environmental and clinical assessments to age 5. This rich data set, linking prenatal and postnatal environments, diverse biological samples and rigorous phenotyping, will inform early developmental pathways to allergy, asthma and other chronic inflammatory diseases.

Repeat self-harm: application of hurdle models.

Among those who present to the emergency department for self-harm, many will repeat. Self-harm repetition is an outcome of interest in both observational and intervention studies. However, few such studies analyse the number of repeat self-harm presentations. Here, hurdle models are introduced as a potentially useful statistical method for these analyses. Emergency department data from the Province of Ontario, Canada, are used to illustrate an example of implementing hurdle models and interpreting their results.

Cats and dogs and the risk of atopy in childhood and adulthood.

BACKGROUND: Exposure to cats and dogs during childhood has been linked to a lower risk of developing allergies. It remains unclear whether this is due to selective avoidance of pets by families with a history of allergies. The effects of pet ownership in adulthood are unknown. OBJECTIVES: We sought to assess the association between cat and dog ownership in childhood and early adulthood and the development of atopy in a population-based birth cohort of 1037 subjects. METHODS: Ownership of cats or dogs between birth and age 9 years and between the ages of 18 and 32 years was reported. Skin prick tests to common allergens were performed at 13 and 32 years. RESULTS: There was no evidence that families with a history of atopy avoided owning pets. There were significant cat-by-dog interactions for the development of atopy in both childhood and adulthood. Children who had owned both a cat and a dog were less likely to be atopic at age 13 years. Living with only one of these animals was not protective against atopy. Among those who were not atopic by age 13 years, having both a cat and a dog in adulthood was associated with a lower risk of new atopy by age 32 years. This association was only significant among those with a parental history of atopy. These effects were independent of a range of potential confounding factors. CONCLUSIONS: There is a synergistic interaction between cat and dog exposure that is associated with a lower risk of developing atopy in childhood and young adulthood.

Temporal and spatial variation of heat-related illness using 911 medical dispatch data.

BACKGROUND: The adverse effect of hot weather on health in urban communities is of increasing public health concern, particularly given trends in climate change. OBJECTIVES: To demonstrate the potential public health applications of monitoring 911 medical dispatch data for heat-related illness (HRI), using historical data for the summer periods (June 1-August 31) during 2002-2005 in Toronto, Ontario, Canada. METHODS: The temporal distribution of the medical dispatch calls was described in relation to a current early warning system and emergency department data from the National Ambulatory Care Reporting System (NACRS). Geospatial methods were used to map the percentage of heat-related calls in each Toronto neighborhood over the study period. RESULTS: The temporal pattern of 911 calls for HRI was similar, and sometimes peaked earlier, than current heat health warning systems (HHWS). The pattern of calls was similar to NACRS HRI visits, with the exception of 2005 where 911 calls peaked earlier. Areas of the city with a relatively higher burden of HRI included low income inner-city neighborhoods, areas with high rates of street-involved individuals, and areas along the waterfront which include summer outdoor recreational activities. CONCLUSIONS: Identifying the temporal trends and geospatial patterns of these important environmental health events has the potential to direct targeted public health interventions to mitigate associated morbidity and mortality.

Development of a surveillance case definition for heat-related illness using 911 medical dispatch data.

OBJECTIVES: The adverse effects of hot weather on public health are of increasing concern. A surveillance system using 911 medical dispatch data for the detection of heat-related illness (HRI) could provide new information on the impact of excessive heat on the population. This paper describes how we identified medical dispatch call codes, called "determinants", that could represent HRI events. METHODS: Approximately 500 medical dispatch determinants were reviewed in focus groups composed of Emergency Medical Services (EMS) paramedics, dispatchers, physicians, and public health epidemiologists. Each group was asked to select those determinants that might adequately represent HRI. Selections were then assessed empirically using correlations with daily mean temperature over the study period (June 1-August 31,2005). RESULTS: The focus groups identified 12 determinant groupings and ranked them according to specificity for HRI. Of these, "Heat/cold exposure" was deemed the most specific. The call determinant groupings with the clearest positive associations with daily mean temperature empirically were "Heat/cold exposure" (Spearman's correlation coefficient (SCC) 0.71, p < 0.0001) and "Unknown problem (man down)" (SCC 0.21, p = 0.04). Within each grouping, the determinant "Unknown status (3rd party caller)" showed significant associations, SCC = 0.34 (p = 0.001) and SCC = 0.22 (p = 0.03) respectively. CONCLUSIONS: Clinically-informed expertise and empirical evidence both contributed to identification of a group of 911 medical dispatch call determinants that plausibly represent HRI events. Once evaluated prospectively, these may be used in public health surveillance to better understand environmental health impacts on human populations and inform targeted public health interventions.

Personal factors influencing agreement between expert and self-reported assessments of an occupational exposure.

This study aimed to identify personal factors associated with expert and respondent agreement on past occupational exposure. Epidemiologic data was collected from 1995 to 1998 in a community-based, case-control study of prostate cancer. Using longest jobs and excluding agreement on "never" exposure, self-reported and expert estimates of ever/ never exposure, by skin or ingestion, to polycyclic aromatic hydrocarbons were compared. Agreement between respondents and the expert was 53.9 percent (N=1,038), with overreporting being more common than underreporting relative to the expert (31.8 percent versus 14.4 percent). In multiple logistic regression models, white-collar occupational status was significantly associated with overreporting (odds ratio [OR] = 0.142; 95 percent confidence interval [CI]: 0.095-0.211; blue-collar versus white-collar), while age was associated with underreporting (OR=1.077; 95 percent CI: 1.043-1.112; one-year increase). Neither job satisfaction nor risk perception appeared to confound other associations. In future studies, overreporting by white-collar workers might be avoided by providing clearer definitions of exposure, whereas elderly respondents may require aids to enhance exposure recall.

Effect of the SARS outbreak on visits to a community hospital emergency department.

OBJECTIVES: To examine the effect of severe acute respiratory syndrome (SARS) on visits to a community hospital emergency department (ED) during the early stage of the Toronto outbreak in 2003 and for the same period in 2004. We focused on visits for respiratory illness (SARS-like symptoms) and different age groups. METHODS: This study is a retrospective review of ED discharge diagnoses obtained from a computerized database, examining the 4-week period starting March 28 for the years 2001-2004. We obtained the discharge diagnosis, age and visit date for each ED patient during the relevant time intervals, then compared visit data from 2003 and 2004 with a baseline derived from the average number of visits during 2001 and 2002. We constructed groupings based on age and respiratory-illness symptoms. RESULTS: During the SARS outbreak in 2003, ED visits declined by 21% (95% confidence interval [CI], 18%-24%) over the 4-week study period. The greatest reduction was for combined infant and toddler visits (69%; 95% CI, 58%-79%); these did not recover the following year. However, during the SARS outbreak there was a large increase in the number of visits for respiratory illnesses in adults (61%; 95% CI, 46%-75%) and in teenagers (132%; 95% CI, 82%-182%). CONCLUSIONS: During the SARS outbreak, total ED visits fell. The relative decline was most notable for infants and toddlers. By contrast, there was an increase in respiratory illness-related visits for adults and teenagers. In 2004, the year following the SARS outbreak, visit patterns shifted toward baseline levels, but ED visits by infants and toddlers remained depressed.

Emergency department presentations for self-harm among Ontario youth.

OBJECTIVES: Self-harm is an important public health issue among youth, including as a major risk factor for suicide (a leading cause of death in this age group). This study used population-based emergency department data to describe clinical and demographic characteristics of emergency department presentations for self-harm among youth (12-17 year-olds) in the province of Ontario, Canada. METHODS: Administrative data capturing every emergency department visit in Ontario between April 1, 2002 and March 31, 2009 were used to identify and describe self-harm presentations. RESULTS: Over the 7-year period between 2002/03 and 2008/09, there were 16,835 self-harm presentations by 12,907 youth. Two thirds of self-harm presentations were self-poisonings (almost always with medicinal agents), followed by self-cutting, which accounted for about one quarter. Incidence rates were higher in girls than boys, increased with age, were inversely related to neighbourhood income and were highest in rural areas. Self-harm accounted for about 1 in 100 emergency department presentations by youth, but also a disproportionate number of presentations triaged as high acuity or admitted to hospital (about 1 in 20). CONCLUSION: Self-harm is an important public health issue, requiring a comprehensive approach to prevention. Ontario has useful data with which to study emergency department presentations for self-harm, and the similarities between self-harm presentations among Ontario youth and those reported from the United States and Europe suggest generalizability of results between populations. Further research is needed to address the reasons for the geographic differences in frequency of self-harm.

Effects of estrogen and aging on the synaptic distribution of phosphorylated Akt-immunoreactivity in the CA1 region of the female rat hippocampus.

The estrogen 17ß-estradiol (E) increases the axospinous synaptic density and plasticity in the hippocampal CA1 region of young female rats but fails to do so in aged female rats. This E stimulus on synaptic plasticity is associated with the phosphorylation-dependent activation of Akt kinase. Our previous findings demonstrated that increased estrogen levels subsequently increase phosphorylated Akt (pAkt)-immunoreactivity (-IR) within the dendritic shafts and spines of pyramidal neurons in young female rats. Therefore, because Akt can promote cell survival and growth, we tested the hypothesis that the less plastic synapses of aged female rats would contain less E-stimulated pAkt-IR. Here, young (3-4 months) and aged (22-23 months) female rats were ovariectomized 7 days prior to a 48-h administration of either vehicle or E. The pAkt-IR synaptic distribution was then analyzed using post-embedding electron microscopy. In both young and aged rats, pAkt-IR was found in dendritic spines and terminals, and pAkt-IR was particularly abundant at the post-synaptic density. Quantitative analyses revealed that the percentage of pAkt-labeled synapses was significantly greater in young rats compared to aged rats. Nonetheless, E treatment significantly increased pAkt-IR in pre- and post-synaptic profiles of both young and aged rats, although the stimulus in young rats was notably more widespread. These data support the evidence that hormone-activated signaling associated with cell growth and survival is diminished in the aged brain. However, the observation that E can still increase pAkt-IR in aged synapses presents this signaling component as a candidate target for hormone replacement therapies.

Estrogen and aging affect the synaptic distribution of estrogen receptor ß-immunoreactivity in the CA1 region of female rat hippocampus.

Estradiol (E) mediates increased synaptogenesis in the hippocampal CA1 stratum radiatum (sr) and enhances memory in young and some aged female rats, depending on dose and age. Young female rats express more estrogen receptor α (ERα) immunolabeling in CA1sr spine synapse complexes than aged rats and ERα regulation is E sensitive in young but not aged rats. The current study examined whether estrogen receptor ß (ERß) expression in spine synapse complexes may be altered by age or E treatment. Young (3-4 months) and aged (22-23 months) female rats were ovariectomized 7 days prior to implantation of silastic capsules containing either vehicle (cholesterol) or E (10% in cholesterol) for 2 days. ERß immunoreactivity (ir) in CA1sr was quantitatively analyzed using post-embedding electron microscopy. ERß-ir was more prominent post-synaptically than pre-synaptically and both age and E treatment affected its synaptic distribution. While age decreased the spine synaptic complex localization of ERß-ir (i.e., within 60 nm of the pre- and post-synaptic membranes), E treatment increased synaptic ERß in both young and aged rats. In addition, the E treatment, but not age, increased dendritic shaft labeling. This data demonstrates that like ERα the levels of ERß-ir decrease in CA1 axospinous synapses with age, however, unlike ERα the levels of ERß-ir increase in these synapses in both young and aged rats in response to E. This suggests that synaptic ERß may be a more responsive target to E, particularly in aged females.

Asthma hospitalization patterns in young children relating to admission age, infection presence, sex, and race.

BACKGROUND: Although childhood hospitalizations for asthma are common, there are few detailed temporal and demographic descriptions of these hospitalizations. OBJECTIVE: To relate temporal patterns of asthma hospitalization in young children to admission age, sex, comorbid infection, and race. METHODS: Retrospective analysis of 151,391 New York State hospitalizations with a principal diagnosis of asthma between January 1, 1990, and December 31, 2004, in children younger than 5 years. Admission patterns across time were related to admission age, sex, race, and comorbid diagnoses of common infections. RESULTS: Although the overall hospitalization rate decreased, it was still 63.8 per 10,000 in 2004. Higher hospitalization rates were consistently observed in children younger than 3 years, African Americans, and boys. Fall increases and summer declines in overall monthly hospitalization rates and monthly median ages exemplified the seasonality observed in the study population. However, admissions with concomitant common infections peaked in the winter, not fall months. Sex did not affect the observed seasonality. Compared with white patients, African Americans not only manifested more than 3-fold higher hospitalization rates but also more repeated hospitalizations. CONCLUSIONS: The concurrent cyclical increases in median age and monthly admissions suggest that seasonal factors affecting older children may relate to fall increases in asthma admissions. These fall peaks are not accounted for by recognizable concomitant common respiratory tract infections. Understanding the basis for these seasonal variations may lead to prevention strategies that could decrease asthma admissions. Asthma hospitalizations in young children continued to be highly prevalent in New York State, especially in African American patients.