1. Department of Internal Medicine, Virginia Tech Carilion School of Medicine, Roanoke, VA 24016, USA
2. Samaritan Health Services, Corvallis, OR 97330, USA
3. Department of Pulmonary & Sleep Medicine, Carilion Clinic, Roanoke, VA 24016, USA
4. Department of Basic Science Education, Liberty University College of Osteopathic Medicine, Lynchburg, VA 24502, USA