1. VA Cooperative Studies Program Coordinating Center, Boston, MA 02130, USA
2. Department of Radiation Oncology, School of Medicine, Case Western Reserve University, Cleveland, OH 44105, USA
3. Department of Pharmaceutical Sciences and Experimental Therapeutics, Fraternal Order of Eagles Diabetes Research Center, Abboud Cardiovascular Research Center, College of Pharmacy, University of Iowa, Iowa City, IA 52242, USA
4. Harvard Medical School, Harvard University, Boston, MA 02115, USA
5. Division of Gastroenterology, Duke University, Durham, NC 27710, USA
6. VA Cooperative Studies Program Epidemiology Center, Durham, NC 27705, USA