Summary and Conclusions There is a growing consensus that large changes in populationlevels of physical activity and other behaviors required toimprove cardiovascular health will require major modifica-tions in environments and policies. Ecological models are theconceptual basis for comprehensive interventions that empha-size environmental and policy changes and that can havewidespread and sustainable effects. These interventions arecomplemented with individual education and motivation andefforts to change social support and norms. Physical activity–specific ecological models indicate which environmental factorsare expected to be related to physical activity in multiple lifedomains: Leisure/recreation/exercise, occupation (school foryouth), transportation, and household. Over the past decade, aproliferation of interdisciplinary research has generally sup-portedhypothesesderivedfromecologicalmodelsandidentifiedspecific built environment attributes and combinations of attri-butes that are related to physical activity, mainly for recreationand transportation purposes, and obesity. It is becoming clearthat racial/ethnic minority and low-income communities aredisadvantaged in access to recreation facilities, positiveaesthetics, and protection from traffic. These results providean empirical rationale for intervention.There are recent examples of environmental changes orcommunity-wide multilevel interventions that had positive ef-fects on physical activity or obesity. Continuing research needsare to improve the rigor of study designs, confirm subgroup- orcontext-specific built environment associations, identify optimalcombinations of attributes, improve understanding of the policychange processes required to achieve environmental changes,and evaluate multilevel interventions.Both research teams and community-based initiatives arecollaborating with a wide range of professionals and sectorsof society, such as recreation, transportation, city planning,architecture, landscape architecture, geography, criminal jus-tice, and law, in addition to health professionals and behav-ioral scientists. These diverse teams have stimulated innova-tions in research, new approaches to intervention, andimproved connections with decision makers who can makeenvironment and policy changes in nonhealth sectors ofsociety. The practice of physical activity promotion, obesityprevention, and CVD risk reduction has changed to reflect theshift to multilevel interventions. Major foundations andpublic health agencies are implementing community-basedinterventions targeting environment and policy change. Con-tinuing challenges for these community-wide interventionsare to maintain support for the multisector, long-term effortsrequired to change environments, evaluate interventions sothey become ever more evidence-based, and integrate explicitchronic disease prevention objectives into professional prac-tices of diverse disciplines, government agencies, and indus-tries whose primary work can affect physical activity andhealth.
Menkes kinky hair syndrome is an X-linked neurodegenerative disorder, causing tissue-specific increases in copper and metallothionein content. A mouse model is provided by hemizygotes for mutant alleles at the X-linked mottled locus. Herein we test the possibility that the primary defect in both species is in metallothionein gene regulation. We show that metallothionein-I messenger RNA (mRNA) (mouse) and metallothionein-II mRNA (human) are elevated in mutant fibroblasts. However, comparable dose-response curves in mutant and control cells are generated when mouse metallothionein-I mRNA concentrations are measured in cells exposed to varying concentrations of cadmium or copper (metallothionein inducers). Furthermore, when mutant and control cells are grown to achieve overlapping intracellular copper concentrations in the two cell types, metallothionein-I (mouse) and metallothionein-II (human) mRNA levels are proportional to the intracellular copper concentrations. Finally, in paired determinations in blotchy hemizygote and littermate kidneys containing comparable copper levels, metallothionein-I mRNA contents are very similar. The observations suggest that elevated intracellular copper in these mutants induces metallothionein synthesis by normal regulatory mechanisms.
Introduction: Physically inactive lifestyles increase the risk of premature mortality and morbidity. Reducing the time young people spend being inactive is particularly important because epidemiologic data suggest physical inactivity tracks better than physical activity from childhood to early adulthood (Malina, 1996) and small reallocations of sedentary time in favour of more active behaviour can be of clinical significance (Blair et al., 1992). Few studies have examined the many ways young people can be inactive and there is conflicting evidence over the impact of sedentary behaviour on levels of physical activity. The purpose of the present study was to examine the prevalence and interrelationships among sedentary behaviours and physical activity in a cross-national sample of youth ages 11–15. Methods: Participants were 2,501 middle school students from the USA (n = 1757, mean age = 12.9 ± 0.92 yr, 59% female) and UK (n = 744, mean age = 13.0 ± 0.94 yr, 85% female). Using a cross-sectional design, a modified version of the Self-Administered Physical Activity Checklist (SAPAC; Sallis et al., 1996) was used to assess levels of physical activity and sedentary behaviour. Participants were asked to recall the frequency and duration of participation (outside of school) in selected physical (n = 32) and sedentary (n = 7) activities during the past seven days. Cluster analysis was used to identify groups of young people who share similar sedentary and physical activity patterns. Results: A three-cluster solution emerged as valid and reliable for both boys and girls. One cluster contained young people who were physically active and reported more sedentary behaviour than their same-sex peers. For boys in this cluster, sedentary time was dominated by technology-based entertainment (labeled 'techno-actives'). For girls in this cluster, sedentary time was spent socialising with friends ('sociable actives'). A second cluster was characterised by low levels of sedentary socialising behaviour but equally high levels of physical activity ('non-socialising actives'). A final cluster contained young people who reported little or no physical activity and lower levels of sedentary behaviour ('uninvolved inactives'). Girls in the inactive cluster were more likely to be from the USA and to be older than girls in the active clusters. Chi-square analyses revealed all other clusters to be invariant with regard to age, self-reported body mass index and ethnicity. Discussion: Duration estimates of multiple sedentary behaviours highlight the many ways young people are inactive. Low intercorrelations between sedentary behaviours suggest youth sedentariness is multifaceted and cannot be accurately represented by any one behaviour such as TV viewing. However, because some sedentary behaviours appear inter-related there exists the possibility for shared determinants and the potential for interventions to shift the distribution of multiple inactive behaviours. There were no instances of negative correlations between physical activity and sedentary behaviour which argues against the assumption that physical activity and sedentary behaviour share an inverse and causal relationship. Further study should examine the health-related outcomes associated with sedentary behaviour that may be independent of physical activity and the modifiable determinants of sedentary behaviour among young people. Acknowledgements: Data collection for the USA sample was supported by grant HL54564, National Institutes of Health. Data collection for the UK sample was supported by a grant from NIKE, Inc.
Protein extraction, co-immunoprecipitation, and immunoblotting were performed in both mouse and human cell lines, as well as in mouse pancreatic tissue. The main steps used in these experiments are described in the manuscript by Antonucci et al., NATCANCER-A11229D.
Mental disorders are of major public health significance. It has been claimed that vigorous physical activity has positive effects on mental health in both clinical and nonclinical populations. This paper reviews the evidence for this claim and provides recommendations for future studies. The strongest evidence suggests that physical activity and exercise probably alleviate some symptoms associated with mild to moderate depression. The evidence also suggests that physical activity and exercise might provide a beneficial adjunct for alcoholism and substance abuse programs; improve self-image, social skills, and cognitive functioning; reduce the symptoms of anxiety; and alter aspects of coronary-prone (Type A) behavior and physiological response to stressors. The effects of physical activity and exercise on mental disorders, such as schizophrenia, and other aspects of mental health are not known. Negative psychological effects from exercise have also been reported. Recommendations for further research on the effects of physical activity and exercise on mental health are made.
Growing empirical evidence documents built environment effects on adults' physical activity, but little is known about environment effects on children's physical activity. Indeed, environments in which adults are active may differ significantly from the environments in which children are active, necessitating a sophisticated approach to public health and environment approaches to increase physical activity across the lifespan. Purpose To examine the relations between the number of places children are active and their levels of physical activity, neighborhood environment, and individual characteristics. Methods Parents of 201 children 4–18 years old were recruited from high and low walkable neighborhoods in King County, WA. Parents reported on the places where their children are active and the places' convenience to their home, their children's activity level, and individual characteristics. Results From a list of 15 potential places in which children could be active in a typical month, friends' homes, own yards, parks, and playgrounds were more frequently visited by children in order to be active than the street and gyms or other paid facilities. The number of places children went to be active was positively related to the number of activity-related facilities convenient to home (<10 minute walk from home) (p<.019), but the number of different children's activity places decreased with child age (p<.007). The number of places a child went to be active was positively related to their level of physical activity (p<.001). In contrast, children went to fewer places to be active when living in neighborhoods marked by environmental factors associated with higher adult physical activity, particularly adults walking for transport (e.g., higher residential density, higher land use mix) (p<.04). Conclusions Children's physical activity appears to benefit from a greater variety of places in which to be active and greater convenience of such activity places. However, the built environment in which adults are more active in the form of walking for transport may not necessarily translate into increased variety in the places in which children are active. Further evaluation of physical activity environments and the potential unique impact of such environments on children is warranted. Supported by NIH grant HL67350.
