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We evaluated perceived social and environmental supports for physical activity and walking using multivariable modeling. Perceptions were obtained on a sample of households in a southeastern county. Respondents were classified according to physical activity levels and walking behaviors. Respondents who had good street lighting; trusted their neighbors; and used private recreational facilities, parks, playgrounds, and sports fields were more likely to be regularly active. Perceiving neighbors as being active, having access to sidewalks, and using malls were associated with regular walking.

Having access to trails is an important environmental feature among low-SES communities and should be the focus of future community-based PA interventions.

Despite differences in content and in response formats, all 3 surveys showed evidence of reliability, and most items are now ready for use in research and in public health surveillance.

The large standard deviations reflect a wide distribution of ambulatory behavior. Regardless, important differences are still evident by demographic characteristics, BMI categories, day of the week, and reported engagement in work or sport/exercise.

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Pelizaeus-Merzbacher disease (PMD)is an X-linked recessive disease caused by coding sequence mutations in the PLP gene, sub-microscopic duplications of variable sizes including the PLP gene or very rarely deletions of the PLP gene. We analysed the X inactivation pattern in blood of PMD female carriers with duplications and with point mutations. In the majority of duplication carriers (7/11), the X chromosome bearing the duplication was preferentially inactivated, whereas a random pattern of X inactivation was detected in point mutation carriers (3/3), a deletion carrier (1/1), affected females (4/4) who did not have a recognised mutation and normal control females. However 2/5 non-carrier female relatives of patients with a duplication, had skewed X inactivation. The skewed pattern of inactivation observed in most duplication carriers and not in mutation carriers suggests a) that there is selection against those cells in which the duplicated X chromosome is active and b) other expressed sequences within the duplicated region rather than mutant PLP may be responsible. Since the skewed X inactivation did not segregate with the disease in two families and the pattern of X inactivation was variable among the duplication carriers, the pattern X inactivation is an unsuitable diagnostic tool for female carriers of PMD European Journal of Human Genetics (2000) 8, 449-454.