1. Department of Internal Medicine, University of Texas Medical Branch, Galveston, Texas.
2. Department of Bioengineering, University of Texas Medical Branch, Galveston, Texas.
3. Department of Cardiovascular Surgery, Methodist Hospital, Houston, Texas.
4. Methodist Research Institute, Houston, Texas.
5. Department of Surgery, Shriners Hospital for Children, Galveston, Texas.
6. Department of Anesthesiology, University of Texas Medical Branch, Galveston, Texas.
7. Department of Surgery, University of Texas Medical Branch, Galveston, Texas.
8. Unit of Physiological Sciences, University of Barcelona, Barcelona, Spain.