1. Geriatric Research, Education and Clinical Center, South Texas Veterans Health Care System, San Antonio, Texas.
2. Research Service, Audie L Murphy Division, South Texas Veterans Health Care System, San Antonio, Texas.
3. Department of Comprehensive Dentistry, University of Texas Health Science Center at San Antonio, San Antonio, Texas.
4. Department of Biomedical Engineering, University of Texas at San Antonio, San Antonio, Texas.