1. Advanced Bioscience Laboratories-Basic Research Program (N.T.), National Cancer Institute-Frederick Cancer Research and Development Center, Frederick, Maryland 21702
2. Department of Physiology (A.W.S., G.M.G.), University of Texas Health Science Center, San Antonio, Texas 78284
3. Department of Surgery (G.G., J.T.R., J.C.T., M.R.H., G.H.G.), The University of Texas Medical Branch, Galveston, Texas 77555
4. Center for Ulcer Research Education: Center for Digestive Disease Research (J.R.R.), Veterans Administration-West Los Angeles, Los Angeles, California 90073
5. Department of Medicine (R.A.L.), Duke University Medical Center, Durham, North Carolina 27710