Southwest Staff
Julian Armstrong, M.D. - Southwest Office
Dr. Julian Armstrong is board certified in gastroenterology and internal medicine. He is a fellow of the American College of Gastroenterology and is a member of the American Gastroenterological Association, The American Society for Gastrointestinal Endoscopy, the Texas Society for Gastroenterology and Endoscopy, the Texas Medical Society, and the Tarrant County Medical Society. He is fluent in English and Spanish and currently serves as the Division Chief for the Gastroenterology Division for North Texas Specialty Physicians.
Dr. Armstrong received his B. A. in chemistry from Bowdoin College in Brunswick, Maine, in 1976 and earned his M.D. at the Albert Einstein College of Medicine in New York City in 1980. He did his residency in Internal Medicine at Madigan Army Medical Center in Tacoma, Washington. After two years as an Internist at Darnall Army Community Hospital in Fort Hood, Texas, Dr. Armstrong completed a fellowship in gastroenterology at Brooke Army Medical Center in San Antonio, Texas. He was Chief of the Gastroenterology Service at Landstuhl Army Regional Medical Center in Landstuhl, Germany from 1987 through 1990 and served as the consultant in gastroenterology for the commanding general for the 7th Medical Command. Dr. Armstrong was honored with the Meritorious Service Medal at the conclusion of his stay. After three years in Europe, he ended his military career at Eisenhower Army Medical Center in Augusta, Georgia, where he was an assistant clinical professor at the Medical College of Georgia.
In 1991, Dr. Armstrong came to Fort Worth with Kaiser Permanente and remained with that organization until its departure from the Texas market. He joined GANT in October 2000.
His hobbies include playing the guitar, exploring local Japanese restaurants, and doing research on classic rock and roll.
Thomas M. Deas, M.D. - Southwest Office
Dr. Thomas M. Deas is board certified by the American Board of Internal Medicine in both Internal Medicine (1981) and Gastroenterology (1989). Dr. Deas began his medical practice in Fort Worth in 1991 after serving 20 years in the U.S. Air Force. His education includes a B.S. in Chemistry from Baylor University, graduating cum laude (1970), followed by a M.S. in Chemistry from Baylor (1971). While serving in the USAF, he received his Medical Degree from Louisiana State University School of Medicine in Shreveport graduating with honors (1978). Postgraduate medical training at Wilford Hall USAF Medical Center in San Antonio included an internal medicine residency (1978-81) and gastroenterology fellowship (1986-88). He is the Medical Director of the Fort Worth Endoscopy Center and the SW Fort Worth Endoscopy Center, which were developed to provide a quality, safe, and convenient endoscopic environment for its patients.
He is a Fellow of the American College of Gastroenterology and American Society for Gastrointestinal Endoscopy (ASGE). He has served in leadership positions with ASGE and North Texas Specialty Physicians. As Chief Medical Officer for SanlotConnect, North Texas' only health information exchange (HIE), Dr. Deas has been an advocate for improving healthcare delivery through health information technology. He is a frequent speaker at national meetings and has published articles on achieving efficient, high-quality gastroenterology practices and endoscopy centers.
A native of Homer, Louisiana, Dr. Deas and his wife of more than 40 years enjoy teaching 3rd grade Sunday school, travel, and leisure time with their children and grandchildren.
Thomas N. Dewar, M.D. - Southwest Office
Dr. Thomas N.Dewar is board certified by the American Boards of Internal Medicine and Gastroenterology., He has practiced in Fort Worth since 1992, where he has been active in hospital leadership activities. He served as President of the Tarrant Academy of Medicine in 2000.
Dr. Dewar was raised in Fort Worth and graduated from R. L. Paschal High School in 1979. He graduated Summa Cum Laude from the University of Texas with a B. A. in biochemistry in 1982. He attended Southwestern Medical School, where he was elected to Alpha Omega Alpha, the medical honor society. He completed his Internal Medicine residency at the University of California at San Francisco, where he served an additional year as Chief Resident. He received his training in Gastroenterology at UCSF before returning to Fort Worth in 1992.
Dr. Dewar has been married to his high school sweetheart for 30 years and has two children, who are both pursuing medical careers. Besides his family, Dr. Dewar's interests include reading, travel, golf, and scuba diving.
Robert Guinan, M.D. - Southwest Office
Dr. Robert Guinan was certified by the American Board of Internal Medicine in 1979 and by the American Board of Gastroenterology in 1981. He received a B. A. with honors degree from the University of Texas at Austin in 1972. Dr. Guinan attended the University of Texas Southwestern Medical School in Dallas. He was awarded his Doctor of Medicine degree in 1976. Dr. Guinan then trained in Internal Medicine at the University of Texas Health Science Center at San Antonio, including internship and residency at Bexar County Hospital and the San Antonio VA Hospital. He underwent further training as a fellow in gastroenterology at the University of New Mexico Medical School and affiliated hospitals in Albuquerque, New Mexico.
Dr. Guinan has practiced gastroenterology in Fort Worth since 1981. He is a member of the Tarrant County Medical Society, Texas Medical Association, American College of Physicians, American Society of Gastroenterology, and the American Society of Gastrointestinal Endoscopy.
Dr. Guinan grew up in Dallas. He and his wife have been married for more than 35 years. They have two daughters. Dr. Guinan enjoys outdoor activities including fishing, bicycling, and golf during leisure time.
Chase R. Herdman, M.D. - Southwest Office
Dr. Chase R. Herdman is board certified by the American Board of Internal Medicine in both Internal Medicine and Gastroenterology. He received a B.S. with Magna Cum Laude graduation honors from Texas A&M University. He earned his M.D. at The University of Texas Health Science Center at San Antonio, where he was elected to Alpha Omega Alpha, a national medical honor society. During the next three years, he completed his internal medicine residency at Vanderbilt University Medical Center in Nashville, Tennessee. He returned to San Antonio for a three-year fellowship in gastroenterology.
He is credentialed in advanced therapeutic endoscopy and ERCP. His other interests include colon cancer screening and general gastroenterology disorders including inflammatory bowel disease, acid reflux disease and irritable bowel syndrome. Dr. Herdman also provides treatment for symptomatic internal hemorrhoids with the CRH-O’Regan banding system.
Dr. Herdman is a member of the American College of Gastroenterology, American Gastroenterological Association, American Society for Gastrointestinal Endoscopy, Texas Society for Gastroentertology and Endoscopy and Tarrant County Medical Society.
Dr. Herdman grew up in Wichita Falls and is happy to call Fort Worth home with his wife and two daughters. In addition to spending time with his family, his hobbies include golf, tennis, hunting, and watching college football. He attends Christ Chapel Bible Church and stays active in his small group bible study.
Carol E. Mallette, M.D. - Southwest Office
Dr. Carol E. Mallette is board certified by the American Board of Internal Medicine in both Internal Medicine and Gastroenterology. She holds a B.A. in biology from Austin College and earned her M.D. from Texas A&M in 2000. She completed her Internal Medicine residency and Gastroenterology fellowship at Brown University in Providence, Rhode Island. Part of her training was spent at Women & Infants Hospital in Providence, obtaining additional experience with female-specific gastrointestinal disorders.
Dr. Mallette has published articles in multiple medical journals and has presented research at the American Gastroenterological Association annual meeting. She is a member of the American College of Gastroenterology, American Gastroenterological Association, American Society for Gastrointestinal Endoscopy, as well as the Texas Medical Association and Tarrant County Medical Society.
Dr. Mallette grew up is south Texas and is happy to be living in Aldeo TX with her husband and two children. She enjoys boating, travel and spending time with her family.
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