The contribution of psychosocial variables in explaining preschoolers' physical activity.

Objective: Based on the theory of planned behavior and the structural model of health behavior, the objectives of this study were to verify whether the psychosocial variables of daycare workers (intention, perceived behavioral control, descriptive norm, past behavior) influence preschoolers' physical activity in daycare centers and determine how these psychosocial variables combine with other factors (environmental, sociodemographic, democratic intervention) to explain children's physical activity.

Method: Forty-six daycare workers from 20 daycare centers in Quebec, Canada completed a self-reported questionnaire assessing psychosocial and sociodemographic variables. Thirty days later, 242 children wore an accelerometer.

How to motivate childcare workers to engage preschoolers in physical activity.

Background: Data available indicate that numerous childcare workers are not strongly motivated to engage children aged 3-5 in physical activity. Using the theory of planned behavior as the main theoretical framework, this study has 2 objectives: to identify the determinants of the intention of childcare workers to engage preschoolers in physical activity and to identify the variables that could be used to develop an intervention to motivate childcare workers to support preschoolers' physical activity.

Methods: 174 childcare workers from 60 childcare centers selected at random in 2 regions of Quebec completed a self-administered questionnaire assessing the constructs of the theory of planned behavior as well as past behavior, descriptive norm and moral norm.

Interactions of the lipopeptide antifungal iturin A with lipids in mixed monolayers.

The miscibility and the interactions of the antifungal lipopeptide iturin A with lipids, DMPC and cholesterol, are studied in monolayers at the air/water interface and a comparison of the respective behaviour of iturin A and the biologically inactive methylated derivative MeTyr-iturin A is made. Each lipopeptide is miscible with anyone of the lipids. This behaviour is revealed by the dependence of the transition pressure upon composition and by deviations from the additivity rule of the mean molecular area.

Methylation of the antifungal lipopeptide iturin A modifies its interaction with lipids.

Iturin A, extracted from the culture media of Bacillus subtilis, is an antifungal lipopeptide, the peptide cycle of which includes a D-Tyr residue in position 2. The antibiotic strength of iturin A is related to a change in the permeability of the membrane cells which leads to a leakage of K+ from the intracellular medium. Methylation of the D-Tyr residue dramatically decreases the biological activity of iturin A.