William M. Tierney, MD, FASGE Professor of Medicine
Director of Endoscopic Ultrasonography Dr. Tierney received his medical degree from Yale University in 1990 and subsequently completed a residency in Internal Medicine at the University of Pennsylvania. He also completed a fellowship in Gastroenterology at the University of Michigan where he received 2 years of dedicated training for EUS and ERCP. He is currently Professor of Medicine at the University of Oklahoma and serves as Director of Endoscopic Ultrasound, Vice Chief of the Section of Gastroenterology, and Director of the Gastroenterology Fellowship Program. He is board certified in Internal Medicine and Gastroenterology and has pioneered several endoscopic procedures in the state of Oklahoma.
John T. Maple, DO Assistant Professor of Medicine
Director of Interventional Endoscopy Dr. Maple was recruited to OU Medical Center in 2007 as an Assistant Professor of Medicine, and was named Director of Interventional Endoscopy in 2008. A native Oklahoman, he attended Oklahoma Christian University and graduated from Oklahoma State University - College of Osteopathic Medicine in 2000. Subsequently, he completed an Internal Medicine residency and Gastroenterology fellowship at Mayo Clinic College of Medicine in Rochester, Minnesota. Dr. Maple then completed an Advanced Endoscopy fellowship at Washington University in St. Louis, focusing on training and clinical research in ERCP and EUS. He is board certified in Internal Medicine and Gastroenterology and has pioneered several endoscopic procedures in the state of Oklahoma.
Javid Fazili, M.D. Dr Frzili is a board-certified gastroenterologist and Associate Professor at the OU College of Medicine. He has a special interest in hepatology and liver transplantation. Fazili completed a fellowship at Albert Einstein Medical Center, Thomas Jefferson University Hospital. He completed a residency at the University Institute of Medical Sciences, Nassau County Medical Center and earned his medical degree from the University of Kashmir.
Ralph T. Guild, III, M.D. Dr. Guild is a board-certified gastroenterologist and a professor at the OU College of Medicine. He sees patients at the VA. He has a special interest in diagnosing and treating patients with Gastroesophageal Reflux Disease and Peptic Ulcer Disease. Guild completed a fellowship and residency at the University of Florida after earning his medical degree at the OU College of Medicine.
Courtney W. Houchen, M.D.
Dr. Houchen is section chief of digestive diseases, Department of Medicine, at the University of Oklahoma College of Medicine. He also holds the Frances & Malcolm Robinson Chair and is an associate professor. Houchen is board-certified in internal medicine and board-eligible in gastroenterology. He has a specific interest in preventing, diagnosing and treating gastrointestinal cancers, colorectal cancer screening, prostaglandin receptor and gastrointestinal injury. He comes to OU Physicians from Washington University School of Medicine, St. Louis, where he completed a gastroenterology fellowship. He completed his residency at the University of Maryland Medical Center, College Park, and earned his medical degree at Temple University School of Medicine, Philadelphia.
Donald J. Kastens, M.D. Dr. Kastens is a board certified gastroenterologist and an Associate Professor at the OU College of Medicine. He has a special interest in diagnosing and treating patients with esophageal motility disorders and Gastroesophageal Reflux Disease. Kastens completed a fellowship, residency and earned his medical degree at the OU College of Medicine.