1. Department of Physiology, University of Maryland School of Medicine, Baltimore, Maryland.
2. Department of Medicine, University of Maryland School of Medicine, Baltimore, Maryland.
3. Baltimore Department of Veteran Affairs Medical Center, Geriatric Research, Education, and Clinical Center (GRECC), Baltimore, Maryland.
4. Research Service, James A. Haley Veterans Hospital, Baltimore, Florida.
5. Department of Internal Medicine, University of South Florida, Tampa, Florida.
6. Third Department of Internal Medicine, Gifu University School of Medicine, Gifu, Japan.
7. Department of Pediatrics, College of Medicine, University of South Florida, Tampa, Florida.