In Memoriam: Richard W. McCallum, MD, FACP, FRACP (AUST), FACG—A Legend in Gastric Physiology and Pathophysiology

Richard W. McCallum, MD, Professor and Founding Chair of the Department of Internal Medicine, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center at El Paso, Texas, an accomplished physician scientist, mentor, doctor of doctors, pioneer, and an esteemed member of the ANMS, passed away peacefully on August 21st, 2025. He was 80 years old and led a full life. A native of Brisbane, Australia, Richard's father, Dr. Norman McCallum, was a distinguished dermatologist. Richard received his medical degree from the Queensland Medical School, University of Queensland, and then moved to the USA to pursue postgraduate medical education, with the intent of returning to Australia. He interned at the Charity Hospital (New Orleans) and then completed his internal medicine residency at Barnes Hospital (St. Louis). Here, he met and married his lifelong bride, Mary Beth. He completed his gastroenterology fellowship at the University of California, Los Angeles, under the tutelage of Drs. Morton Grossman, John Walsh, Charlie Code, and Jon Isenberg, the "kings" of GI physiology, followed by a short faculty stint at UCLA. Thereafter, he was recruited to Yale University, where he served as a faculty member for almost a decade. In 1985, he was appointed chief of gastroenterology at the University of Virginia in Charlottesville, VA, and was endowed with the Paul Janssen Professorship in Medicine. The next 10 years were his golden decade as he built a strong clinical and basic science GI division. In an era when nobody believed that Helicobacter pylori could cause peptic ulcer disease, Dr. McCallum had the foresight to recruit Dr. Barry Marshall, who proved this link and was subsequently awarded the Nobel Prize in Physiology or Medicine. In 1995, Dr. McCallum was recruited to Kansas University Medical Center as Chief of Gastroenterology/Hepatology, and in 2009 became Professor and Founding Chair of the Department of Internal Medicine at El Paso, Texas. In 2015, he was also appointed an honorary Professor of Medicine at his alma mater, University of Queensland, Brisbane, Australia. A true out-of-the-box thinker, he transformed ideas into innovations that changed the lives of countless patients. He collaborated with Dr. Jiande Chen to develop a portable gastric pacemaker. Later, under Dr. McCallum's direction, the first gastric electrical stimulation (GES) system, "Enterra" for gastroparesis was implanted on April 1, 1998, at Kansas University. Since then, tens of thousands of patients have received this therapy—a testament to his foresight as a pioneer. Under his leadership, his team has carried out a large number of clinical trials, testing new pharmacologic treatments and pushing forward cutting-edge diagnostic tools such as wireless motility capsules for neurogastroenterology and motility diseases. As one of the founding members of the NIH/NIDDK Gastroparesis Clinical Research Consortium, Dr. McCallum was continuously funded for more than 15 years and helped to raise awareness of gastroparesis. In the consortium, he spearheaded research on domperidone, joint hypermobility syndrome and gastroparesis, and evaluation of Carnett's sign for abdominal pain in gastroparesis. He was often the highest enroller in clinical trials. He was extremely nurturing of colleagues, an example of which is Drs. Irene Sarosiek and Jerzy Sarosiek, who worked with him for more than 30 years, as well as inspiring others including Ravinder Mittal, MD, and Jiande Chen, PhD. He has authored more than 500 peer-reviewed articles, 130 textbook chapters, and has edited over 15 scientific textbooks, including the widely used Handbook on Gastrointestinal Motility and Disorders of Gut-Brain Interactions, which he co-edited with Drs. Satish Rao and Henry Parkman. He held multiple patents. The impact of Dr. McCallum's work is reflected by the many honors and awards he has received throughout his distinguished career. This includes the Chancellor's Council Distinguished Research Award from the Texas Tech University System (2015), the Gold Medal for Excellence in Academic Medicine from the Texas Medical Association (2016), and the Washington University Medical Center Resident/Fellow Alumni Achievement Award (2017). Perhaps the best recognition of Dr. McCallum's legacy was the Neurogastroenterology the innumerable trainees he mentored, and the enduring impact of his work in gastrointestinal motility. Beyond academia, he was an ardent sports enthusiast who never missed an NCAA basketball game, Kansas football match, or Australian cricket test. He took pride in sharing his NCAA bracket each year and fiercely competed with young and old alike. A passionate tennis player, he also loved to travel, meet friends, ballroom dance, attend the symphony, and even body surf. Well-known for his tireless work ethic, it was not uncommon to receive emails from him after midnight, his most productive time of the day! He is survived by his beloved wife Mary Beth, his daughters Elizabeth and Heather, sons-in-law Marshall and Franklin, his son Yates and daughter-in-law Lexi, and his most cherished grandchildren: Summer, Huck, Zeke, Colette, Ren, and Dash, and sister Sue Roberts. All authors have contributed equally for this article. The authors declare no conflicts of interest.