1. National Aeronautics and Space Administration Johnson Space Center, Houston, Texas.
2. Cedars-Sinai Medical Center, Los Angeles, California.
3. University of Texas Medical Branch, Galveston, Texas.
4. University of Texas Southwestern Medical Center, Dallas, Texas.
5. Division of Cardiology, The Ohio State University, Columbus, Ohio.
6. University of Waterloo, Waterloo, Ontario, Canada.
7. Mount Sinai School of Medicine, New York, New York.
8. John B. Pierce Laboratory, Yale School of Medicine, New Haven, Connecticut.
9. Emory University School of Medicine, Atlanta, Georgia.