1. The Richard L. Roudebush Veterans Affairs Medical Center and
2. Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana;
3. Departments of Medicine and Physiology, Université de Montréal, Hôpital du Sacré-Coeur de Montréal, Montréal, Québec, Canada; and
4. INSERM Unit 872, Université Pierre et Marie Curie (Paris VI), Centre de Recherche des Cordeliers, Paris, France