Dr. Powell is currently the Director of the General Clinical Research Center, and Director of the Division of Gastroenterology and Hepatology in the Department of Internal Medicine and Professor of Internal Medicine and Neuroscience and Cell biology at The University of Texas Medical Branch (UTMB) in Galveston. Dr. Powell stepped down from the Chair of Internal Medicine at UTMB in 2002, a position he held for 12 years and he served as Associate Dean for Research fro 2002-2006. Dr. Powell earned his medical degree from the Medical College of Alabama, Birmingham. He then did his residency training at Peter Bent Brigham Hospital in Boston and at Yale-New Haven Community Hospital and completed a Special National Institutes of Health Fellowship in Physiology at Yale University School of Medicine. He was a member of the faculty at UNC for 20 years, where he was Professor of Medicine and the Chief of the Division of Digestive Diseases and Nutrition and Director the NIH-funded Center for Gastrointestinal Biology and Disease.

He has been funded by the NIH for research in gastrointestinal science for over 40 years. He has served on Study Sections and Advisory Committees at the NIH, the editorial boards of numerous medical and scientific journals and as Associate Editor of the Cecil Textbook of Medicine and the Yamada Textbook of Gastroenterology, now in its 5th edition. He has authored and co-authored over 200 peer-reviewed journal articles, textbooks and chapters, teaching aids, reviews, and editorials. He has been an Associate Editor of the Yamada Textbook of Gastroenterology for five editions and of Cecil Textbook of Medicine for two editions. Dr. Powell served on the American Board of Internal Medicine (ABIM) Board of Directors from 1996 to 20000. In 1993-1994 he served as President of the American Gastroenterological Association (AGA) and in 2001 was given the Friedenwald Medal from the AGA in recognition of lifetime achievement in gastroenterology. He was honored as a Master of the American College of Physicians in 1999. In 2002, he received the John P. McGovern, M.D. Award in Oslerian Medicine from UTMB. He was elected as a Fellow in the American Association for the Advancement of Science (AAAS) in 2003, received the AGA Mentors Research Scholar Award in 2005, and was elected as an AGA Fellow in 2006. The inaugural Don W. Powell Lecture was held in 2007, made possible by an endowment from the Edward and Sally Futch Charitable Fund in honor of Dr. Powell.

Dr. Powell has been awarded NIH funding for over 40years to study mechanisms of intestinal electrolyte transport and, at present, his interest has turned to the immune system control of these processes, COX-2 gene regulation, immunology of mesenchymal cells and colon cancer microenvironment.

Research in the lab focuses upon the biology of intestinal myofibroblasts (IMF). These cells are members of a family of phenotypically-related cells that include glomerular mesangial cells, renal and pulmonary interstitial fibroblasts and hepatic and pancreatic stellate cells. Located at the interface between the epithelium and lamina propria, IMF modulate information transfer between these tissue compartments and play a pivotal role in immunology, physiology, development, and carcinogenesis of the gastrointestinal tract. These cells are likely to play an important role in the etiology of colon cancer, inflammatory bowel disease (IBD) and immune tolerance. Ongoing projects involve:

1. Regulation of cyclooxygenase-2 (COX-2) gene expression in IMFs. This NIH funded research combines biochemical, molecular biological, and histochemical approaches to understand signaling pathways that regulate COX-2 in IMFs. This research is significant since COX-2 expression is observed in IMF during the early stages of colorectal carcinogenesis and the chemopreventive effects of nonsteroidal anti-inflammatory drugs derive from their ability to inhibit synthesis of COX-derived prostaglandins.

2. IMF as novel immune regulators. This research combines immunological, molecular biological, and histochemical approaches to understand how IMF interact with immune cells to modulate intestinal inflammation and possibly tolerance to dietary and bacterial antigens present in the intestinal lumen. In collaboration with the laboratory of Dr. Victor Reyes (Microbiology and Immunology), experiments are being conducted to characterize class II MHC-mediated antigen presentation by IMF and the ability of antigen presenting IMF to either stimulate a T cell mediated immune response, or to promote antigenic tolerance or anergy. Knowledge derived from these studies will be used to determine defects associated with IMF in IBD and celiac disease.

3. IMFs form the stem cell niche for the intestinal epithelium by secreting factors (Wnts, BMPs, various antagonists) and matrix molecules that control stem cell growth. Their role in development and colon cancer is a new area of research in this laboratory.

1. Saada JI, Pinchuk IV, Barrera CA, Adegboyega PA, Suarez G, Mifflin RC, Di Mari JF, Reyes VE, Powell DW. Subepithelial myofibroblasts are novel non-professional APCs in the human colonic mucosa. J Immunol 177:5968–5979, 2006.

2.Pinchuk IV, Beswick EJ, Saada JI, Suarez G, Winston J, Mifflin RC, Di Mari JF, Powell DW, Reyes VE. MCP-1 production by intestinal myofibroblasts in response to staphylococcal enterotoxin A: Relevance to staphylococcal enterotoxigenic disease. J Immunol 178:8097-8106, 2007.

3. Beswick EJ, Pinchuk IV, Das S, Powell DW, Reyes VE. Expression of the programmed death ligand 1, B7-H1, on gastric epithelial cells after helicobacter pylori exposure promotes development of CD4(+) CD25(+) FoxP3(+) regulatory T cells. Infect Immun 75:4334-4341, 2007.

4. Di Mari JF, Saada JI, Mifflin RC, Valentich JD, Powell DW. HETEs enhance IL-1-mediated COX-2 expression via augmentation of message stability in human colonic myofibroblasts. Am J Physol Gastrointest Liver Physiol 293:719-728, 2007.

5. Kosinski C, Li VSW, Chan ASY, Zhang J, Ho C, Tsui WY, Chan TL, Mifflin RC, Powell DW, Yuen ST, Leung SY, Chen X. Gene expression patterns of human colon tops and basal crypts and BMP antagonists as intestinal stem cell niche factors. Proc Nat Acad Sci 104:15418-15423, 2007.

His clinical expertise lies in inflammatory bowel and diarrheal diseases.

1.Semrad CE, Powell DW. Approach to the patient with diarrhea and malabsorption. In: Lee Goldman and Dennis Ausiello (Eds.). Associate Editors: WP Arend, JO Armitage, DR Clemmons, JM Drazen, RC Griggs, N LaRusso. Cecil Textbook of Medicine, 23rd Edition. Saunders Elsevier, Philadelphia, 1019-1041, 2007.

2. Yamada T, Alpers DH, Kaplowitz N, Kalloo A, Owyang C, Powell DW (eds). Textbook of Gastroenterology 5th Edition, Blackwell Publishing, Oxford, UK, In Press.

3. Yamada T, Alpers DH, Kaplowitz N, Kalloo A, Owyang C, Powell DW (eds). Atlas of Gastroenterology 4th Edition, Blackwell Publishing, Oxford, UK, In Press.

4. Yamada T, Alpers DH, Kaplowitz N, Kalloo A, Owyang C, Powell DW (eds). Principles of Clinical Gastroenterology, 1st Edition, Blackwell Publishing, Oxford, UK, In Press.

Address:	301 University Blvd., Galveston, Tx, 77555-0764
Email:	dpowell@utmb.edu
Office:	409-772-1501