1. Pittsburgh Heart, Lung, and Blood Vascular Medicine Institute
2. Division of Pulmonary, Allergy and Critical Care Medicine
3. Center for Pulmonary Vascular Biology and Medicine, and
4. Division of Cardiology, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
5. Department of Medicine, Alpert Medical School, and
6. Department of Health Services, Policy, and Practice, School of Public Health, Brown University, Providence, Rhode Island; and
7. Department of Internal Medicine, Justus-Liebig University Giessen, Giessen, Germany