Zahra Ghiassi-Nejad, MD, PhD

Dr. Ratner is Professor of Surgery and Director of Renal and Pancreatic Transplantation at Columbia University. Prior to joining the faculty at Columbia, Dr. Ratner was on the faculty of Johns Hopkins University in Baltimore, and served as the Chief of Solid Organ Transplantation at Thomas Jefferson University in Philadelphia. Dr. Ratner was responsible for dramatic growth of the kidney transplant program at CUIMC. He also established the pancreas transplant program, and the Kidney Autotransplant Program. He introduced robotic surgery to our kidney transplant program. Access to organ transplantation has been Dr. Ratner's major academic interest. Dr. Ratner has been a leading innovator in transplantation for over two decades. In 1993, he performed the world's first dual renal transplant. In 1995 (with Dr. Louis Kavoussi) he performed the first laparoscopic donor nephrectomy, and set the stage for its widespread adoption, which resulted in a profound increase in living donor kidney transplantation. Dr. Ratner has made significant contributions in overcoming immunologic incompatibilities that prohibited transplantation. He devised the plasmapheresis/IVIg protocol for alloantibody desensitization in 1998. In 2001, Dr. Ratner orchestrated the second paired-kidney exchange in the U.S. Subsequently, he arranged the first paired kidney exchanges in both Pennsylvania and New York. More recently Dr. Ratner has been a leading proponent of including compatible donor/recipient pairs in kidney exchanges. And, his more contemporary work has looked at the organizational and regulatory barriers to access to care. All of these strategies have increased organ availability and access to transplantation. Additionally, he has made important contributions to improve living donor safety. For his work, Dr. Ratner has received numerous awards and honors. And, he has been invited to speak and operate at various venues around the world. Dr. Ratner has authored or co-authored over 240 peer-reviewed publications, and has been a federally funded investigator. His publications have been cited over 20,000 times. He served as the Chairman of the Board of Directors of the LiveOnNY (formerly the New York Organ Donor Network), and has served on numerous national committees including the Board of the Organ Procurement and Transplantation Network (OPTN). He recently completed a term as the President of the American Society of Transplant Surgeons, and previously served as that Society's Treasurer.Dr. Ratner originally hails from Brooklyn, NY. He received his undergraduate education at the State University of New York at Buffalo. He received his M.D. from Hahnemann University. His general surgery training was obtained at Long Island Jewish Medical Center. He completed a Fellowship in Transplantation Surgery and Immunology at Washington University. In 2011 Dr. Ratner completed a Master of Public Health with a focus on health care policy, administration and management.

Dr. Oberfield, a professor of pediatrics, has been the director of the Division of Pediatric Endocrinology, Diabetes, and Metabolism at Columbia University Irving Medical Center since 2004. Throughout her career, Dr. Oberfield has been dedicated to educating the next generation of pediatric endocrinology sub-specialists. She was for many years director of the fellowship training program in pediatric endocrinology, and is currently associate program director. Since 2005 she has been the principal investigator of a T32 training grant in pediatric endocrinology from the NIH National Institute of Diabetes, Digestive, and Kidney Diseases, one of only a handful of such programs in the country. Since 1998, she has mentored more than 35 fellows and more than 30 pre-doctoral students including Endocrine Society, DERC, and Doris Duke summer fellows. From 2021-2022 Dr. Oberfield served as president of the Lawson Wilkins Pediatric Endocrine Society (PES), an international organization of more than 1,300 members, that provides resources for healthcare professionals and trainees and affords educational support for patients and families affected by disorders of the thyroid, adrenal, and pituitary glands; growth disturbances; and conditions of bone metabolism and diabetes. Her priorities as president, she says, were “to maintain and expand the relevance of bench, translational and clinical researcher as well as the importance of the practicing pediatric endocrinologist, even in an era when delivery of health care and research related to children and adolescents is being dramatically eroded.” Dr. Oberfield has been engaged in patient-oriented research for her entire career, with a particular focus on disorders of adrenal hormone synthesis, adrenarche, and PCOS. She has conducted studies of body composition in children and continues to be involved in multiple studies of childhood obesity. Her clinical research has centered around the developmental/pediatric endocrinology, specifically the HPA axis which intimately affects metabolic function, interacting with adiposity, including studies of body composition in adrenarche and PCOS. She has been the author or co-author of more than 225 articles, multiple chapters and reviews, and is an invited speaker at national and international meetings, including the 2012 NIH-sponsored Evidence Based Methodology Workshop on Polycystic Ovary Syndrome. She is currently an editor for the Journal of Pediatrics and is an associate editor for Hormone Research in Pediatrics. She continues to be listed in Castle Connelly’s “America’s Top Doctors” and NY Magazine’s “Best Doctors."

David Horowitz, M.D. is a board-certified radiation oncologist and Associate Professor of Radiation Oncology at New York-Presbyterian/Columbia University Irving Medical Center. His clinical focus is on gastrointestinal cancers, lymphoma and breast cancer, and his research interests focus on the development of novel ways to deliver precision radiation therapy to hard-to-treat cancers. Dr. Horowitz received his B.A. from Dartmouth College and his M.D. from the Johns Hopkins University School of Medicine, during which time he completed a research fellowship in the Department of Radiation Oncology and Molecular Radiation Sciences. He completed his internal medicine internship training at the Georgetown University/Washington Hospital Center after which he completed his radiation oncology training at New York Presbyterian Hospital (Columbia University Medical Center Campus), where he additionally served as Chief Resident. Dr. Horowitz has developed the use of multiple radiation techniques at the Columbia University Irving Medical Center to best help patients with cancer receive the most effective treatments while minimizing potential side effects. These include stereotactic body radiation therapy (SBRT), stereotactic radiosurgery, hypofractionated ablative radiation therapy, intensity modulated radiation therapy, image-guided radiation therapy, intraoperative radiotherapy, brachytherapy, total body irradiation, and total skin electron beam therapy. As a member of the Pancreas Center at Columbia, Dr. Horowitz is part of a multidisciplinary team that brings expertise from multiple specialties, including surgery, medical oncology and radiology to the care of complex patients with pancreas cancer. Outside of his clinical duties, Dr. Horowitz serves as Director of Medical Student Education in the Department of Radiation Oncology, as well as the Associate Program Director for the department's residency program. Dr. Horowitz has mentored numerous medical students and residents, with multiple mentees receiving competitive research grants from the NIH, American Medical Association, and Gold Foundation. For a list of publications, please visit Pubmed.gov