1. VA GI Hemostasis Research Unit, Los Angeles, California, USA;
2. Department of Medicine Keck School of Medicine of the University of Southern California, Los Angeles, California, USA;
3. Gastroenterology Division, Department of Medicine, VA Greater Los Angeles Healthcare System, Los Angeles, California, USA;
4. Vatche and Tamar Manoukian Division of Digestive Diseases, Department of Medicine, Ronald Reagan UCLA Medical Center, Los Angeles, California, USA;
5. David Geffen School of Medicine at University of California, Los Angeles, California, USA.