Moving targets: bicycle-related injuries and helmet use among university students.

We conducted a cross-sectional study to evaluate bicycling habits and helmet use in a sample of university students in a southwestern state university. Thirty-one of 100 students in our sample owned bicycle helmets; of these, 17 (54.8%) wore helmets during most (more than three fourths) of their bicycle trips. Almost half of the students reported that more than 25% of their bicycling was done in heavy traffic but they rarely used bicycle trails. Sixty-five students in the sample had sustained at least one minor injury during the previous 5 years, and 18 had been hospitalized as a result of bicycle-related injuries. We found no substantial differences between male and female subjects in bicycle-related hospitalizations, although male subjects were more likely to sustain minor injuries than were females. Helmet ownership was most strongly associated with previous injury experience, especially hospitalization resulting from bicycling injuries (OR = 3.6; 95% CI = 1.3, 10.1). We also observed an association between helmet ownership and possession of insurance coverage for bicycling injuries (OR = 3.0; 95% CI = 1.2, 7.6). Ethnicity was a factor in helmet ownership--helmets were owned by 26 of 69 (37.7%) of non-Hispanic whites, in contrast to 1 of 24 (4.2%) of all other ethnic groups combined. Our survey data suggest that perceived risk is an important factor in bicyclists' use of safety helmets.     

Children's attitudes to parents', teachers' and employers' perceptions of term‐time employment

This article is concerned with examining working children's perceptions of how adults in a range of different settings view their employment. In particular, the article explores how participation in the labour market influences adult‐child relationships within the home, at school and at work. Children interact with adults across a variety of different spheres. Dependence and independence permeate children's relationships with adults in different social settings. Entry to the labour market and access to earnings promotes responsibility among children and encourages self‐reliance. The purpose of the article is to assess the extent to which these traits affect children's interaction with adults within and across the social spaces of the home, school and place of employment. Copyright © 2003 John Wiley & Sons, Ltd.     

Moving targets: determinants of nutritional preferences and habitat use in an urban ant community

Urban environments are often associated with reduced biodiversity, presumably because they are typically more fragmented, warmer, and drier than nearby non-urban environments. However, urban landscapes offer significant complexity that have allowed some taxonomic groups to flourish. Understanding how urban-exploiting animals navigate this spatiotemporal heterogeneity is important given the continued global urban land expansion. Here, we examined the factors influencing resource-use in an urban community of ants, which represent a widespread and important taxon in urban ecosystems. In particular, we sought to integrate ants’ nutritional, thermal, and spatial niches to better understand how urban animals successfully access critical resources throughout their active season. Meteorological season (spring, summer, and fall) and/or species (n?=?9) influenced ants’ preferences for nutrition (ratio of ingested protein-to-carbohydrate ratio), as well as the temperature, type (impervious vs. non-impervious), and shade status (shaded vs. non-shaded) of surfaces used during activity. Our data also indicate links among habitat variables, as well as between nutritional preferences and habitat use. Together, our results suggest that species and seasonality influence ecological (combined nutritional, thermal, and spatial) niches in an urban community. We encourage future work in urban ecosystems that continues to integrate more features of the ecological niche, and to examine the outcomes of variation in niches (e.g., non-overlapping niches may explain both the persistence of some native animals and the success of invaders).     

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Aging is a complex process modulated by multiple interactions between environmental and genetic factors. Myotonic dystrophy (DM 1) is an autosomal dominant disorder caused by an unstable (CTG)_n repeat expansion in the DM1 protein kinase (DMPK) gene. The affected male patients' life expectancy at birth (53.2 years) is more than two decades below that observed in most occidental populations. The DMPK gene expression is pleiotropic and includes the premature expression of several agerelated signs, symptoms and metabolic disturbances including hormonal dysfunctions, progressive decrease in muscular mass, presenile cataracts, alopecia, reduced alertness, insulin resistance, dyslipidemia, erectile dysfunction and hypogonadism. The aim of this study was to analyze the relationship between aging covariates and the severity of DM1 expression in 136 DM1 male subjects. DM1 clinical expression was assessed on a validated neuromuscular disability rating scale and was correlated with plasma total testosterone (r_s = -0.31, p < 0.001), luteinizing hormone (LH) (r_s = 0.52, p < 0.001) and follicle stimulating hormone (FSH) (r_s = 0.54, p < 0.001) levels. Following LH releasing hormone stimulation, FSH and LH concentrations increased as a function of DM1 severity (p < 0.05). Muscular disability in DM1 was also positively associated with fasting plasma insulin and triglyceride concentrations (p < 0.05). The association of plasma apolipoprotein B and low-density lipoprotein cholesterol levels with DM1 was not linear across their distribution and tended to reflect cell membrane damage progression. These results suggest that DM1, a simple M endelian trait, can represent a valuable model to illustrate the complex relationships between variables associated with male aging.     

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Background.?Saliva collection is an easy, non-invasive method to measure hormones.

Methods.?Two studies were performed. In the first, a convenience sample of 1454 males who had submitted saliva for salivary testosterone measurements were studied. In the second study, we intensively studied symptoms and measurements of total testosterone, free testosterone symptoms and measurements of total testosterone, free testosterone and bioavailable testosterone in relationship to salivary testosterone in 127 men. A secondary endpoint was to examine the relationship of salivary testosterone to hypogonadal symptoms in the ADAM and AMS questionnaires.

Results.?In the first study, we have shown that salivary testosterone, measured in 1454 males aged 20 to 89 years, declines by 47% over the lifespan. In the second study, salivary testosterone was strongly correlated with bioavailable testosterone (p < 0.000001) calculated free testosterone (p < 0.00001) and total testosterone (p < 0.002). Salivary testosterone was significantly related to hypogonadal symptoms on the St. Louis University ADAM questionnaire and the Aging Male Survey.

Conclusions.?These studies support the use of salivary testosterone as an acceptable assay for screening for hypogonadism. Salivary testosterone is not a better assay than other measures to diagnose hypogonadism.