1. Department of Research Programs, Fort Belvoir Community Hospital, Fort Belvoir, Virginia.
2. Laboratory of Epidemiology and Population Sciences, National Institute on Aging, NIA/NIH/IRP, Baltimore, Maryland.
3. Department of Obstetrics and Gynecology, Jones Institute for Reproductive Medicine, Eastern Virginia Medical School, Norfolk, Virginia.
4. Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland.