1. Michael E. DeBakey VA Medical Center, Houston, Texas, USA.
2. Baylor College of Medicine, Houston, Texas, USA.
3. Oklahoma City VA Medical Center, Oklahoma City, Oklahoma, USA.
4. University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, USA.
5. Oklahoma Medical Research Foundation, Oklahoma City, Oklahoma, USA.
6. Langston University, Langston, Oklahoma, USA.