1. South Texas Veterans Health Care System, San Antonio, Texas, USA;
2. University of Illinois at Chicago College of Medicine, Chicago, Illinois, USA;
3. Michael E. DeBakey VA Medical Center, Houston, Texas, USA;
4. University of Texas Southwestern Medical Center at Dallas, Dallas, Texas, USA;
5. Fort Carson Army Medical Center, Colorado Springs, Colorado, USA;
6. South Texas Veterans Health Care System, San Antonio, Texas, USA