1. Laboratory of Epidemiology, Demography and Biometry, National Institute on Aging, Bethesda, Maryland
2. Department of Clinical and Experimental Medicine, University of Ferrara, Ferrara, Italy
3. Geriatric Department, Italian National Institute for Research and Care on Aging (INRCA), Florence, Italy
4. Departments of Medicine and Epidemiology, the Johns Hopkins Medical Institutions, Baltimore, Maryland
5. Sealy Center on Aging, University of Texas Medical Branch, Galveston, Texas
6. Division of Endocrinology, Diabetes, and Nutrition, University of Maryland School of Medicine, Baltimore, Maryland