1. Sainte-Justine Hospital Research Center, University of Montreal, 3175 Chemin de la Côte-Sainte-Catherine, Room B-467, Montreal, QC, Canada H3T 1C5
2. Department of Pediatrics, Faculty of Medicine, University of Montreal, 3175 Chemin de la Côte-Sainte-Catherine, Room 7955, Montreal, QC, Canada H3T 1C5
3. Department of Social and Preventive Medicine, Faculty of Medicine, University of Montreal, P. O. Box 6128, Station Centre-Ville, Montreal, QC, Canada H3C 3J7