1. Yale School of Medicine , New Haven, CT , USA
2. University of Alabama at Birmingham , Birmingham, AL , USA
3. Mayo Clinic , Scottsdale, AZ , USA
4. Vanderbilt University Medical Center , Nashville, TN , USA
5. University of Virginia , Charlottes ville, VA , USA
6. University of California , San Francisco, San Francisco , USA
7. UT Southwestern Medical Center , Dallas, TX , USA