GI & Hepatology Physicians

Jonathan Buscaglia, MD, Chief, Division of Gastroenterology and Hepatology, and Director of the Interventional Endoscopy
Dr. Buscaglia received his undergraduate medical education in 2001 from the University at Buffalo, part of the State University of New York (SUNY) system. He completed medical internship and residency at Montefiore Medical Center in the Bronx, New York. He then finished gastroenterology fellowship and the advanced endoscopy fellowship program at Johns Hopkins Hospital in Baltimore, Maryland. Jonathan joined the medicine faculty at SUNY Stony Brook in 2008, where he is now Associate Professor of Medicine with tenure. He has served as both Director of Endoscopy and Director of Interventional Endoscopy at Stony Brook, and is now Chief of the Division. Jonathan is past President of the New York Society for Gastrointestinal Endoscopy (NYSGE), and has been recognized in New York Magazine and by Castle Connolly as one of the region's Top Doctors.

Dr. Buscaglia is a recognized expert in the field of advanced endoscopy and pancreatic-biliary diseases. He has conducted pioneering research in natural orifice transluminal endoscopic surgery (NOTES), therapeutic endoscopic ultrasound (EUS), and more recently in the area of pancreatic cancer for which he has received external grant funding. His practice focuses on GI oncology, and he specializes in endoscopic retrograde cholangiopancreatography (ERCP), diagnostic and therapeutic EUS, and advanced endoscopic resection techniques.

Eyad Ali, MD, is board-certified in gastroenterology and hepatology, with expertise in a wide area of general common gastrointestinal disorders including reflux, irritable bowel syndrome, hepatitis, and inflammatory bowel disease. He is an Assistant Professor of Medicine, Division of Gastroenterology and Hepatology, at Stony Brook School of Medicine.

Juan Carlos Bucobo, MDAssociate Professor of Medicine, Chief of Endoscopy
Dr. Bucobo is an advanced endoscopy expert, specializing in endoscopic ultrasound (EUS), endoscopic mucosal resection (EMR), endoscopic retrograde cholangiopancreatopography (ERCP), endoluminal stent placement and deep small bowel enteroscopy. He is an Associate Professor of Medicine, Division of Gastroenterology and Hepatology at Stony Brook School of Medicine. 

Edward H. Cheng, MD, Co-Chair, Nutrition Committee at the Veteran’s Affairs Medical Center, Northport, NY
Dr. Chen is a board-certified gastroenterologist with an expertise in capsule endoscopy, breath tests, pH monitoring, immunology and H. pylori. He is an Associate Professor of Medicine, Division of Gastroenterology and Hepatology, at Stony Brook School of Medicine.

Tyson Collazo, MD, Assistant Professor, Department of Medicine
Dr. Collazo is an Assistant Professor of Medicine at Stony Brook School of Medicine. His practice encompasses both Gastroenterology and General Hepatology. He completed Medical School and Internal Medicine Residency at the Icahn School of Medicine at Mount Sinai, and Gastroenterology Fellowship at Westchester Medical Center. Having trained at Liver Transplant Centers for both Residency and Fellowship, Dr. Collazo has a special interest in treating Liver Disease, including Viral Hepatitis, Autoimmune Hepatitis, Cirrhosis, Metabolic Disorders of the Liver, Primary Biliary Cholangitis, Primary Sclerosing Cholangitis, and Endoscopic Management of Esophageal Varicies. Dr. Collazo works closely with Transplant Hepatologists at Mount Sinai Medical Center to facilitate care for patients in need of liver transplantation.

Dr. Collazo also sees all facets of General Gastroenterology Disorders including , Acid Reflux (GERD), Barrett's Esophagus, Celiac Disease, Constipation, Colon Cancer and Polyp Screening, Diarrhea, GI Bleeding, Dysphagia, Eosinophilic Esophagitis, Irritable Bowel Syndrome, Small Intestinal Bacterial Overgrowth, and performs Upper Endoscopy, Colonoscopy, and Wireless Capsule Endoscopy.

Deepak Desai, MD, Assistant Professor of Medicine, Program Director GI Fellowship, Chief of Gastroenterology VAMC Northport
Deepak S. Desai, MD, Chief, Division of Gastroenterology and Hepatology, Northport Veterans Affairs Medical Center and Program Director, Gastroenterology Fellowship Program, State University of New York at Stony Brook.

Dr. Desai previously served as the Associate Chair of Medicine at North Shore University Hospital, Northwell Health in addition to the Divisional Director of Quality and sole GI Hospitalist on the Northwell full time academic faculty.

Dr Desai’s interests include management of acute GI/hepatic disease processes, endoscopic management of GI bleeding, medical education and quality management / research.

He completed GI Fellowship training at the University of Miami and Medicine Residency and Chief Residency at SUNY Stony Brook.

Lionel S. D’Souza, MD, Director, Endoscopic Surgery
Dr. D’Souza is an Assistant Professor of Medicine, Division of Gastroenterology and Hepatology at Stony Brook School of Medicine. He is a member of the Advanced Diagnostic and Therapeutic Endoscopy team at Stony Brook University Hospital with expertise in pancreatic diseases, biliary tract diseases and malignant and pre-malignant tumors of the gastrointestinal tract. He specializes in endoscopic retrograde cholangiopancreatography (ERCP), diagnostic and therapeutic endoscopic ultrasound (EUS), endoscopic mucosal resection (EMR) and endoluminal stent placement. Dr. D’Souza has a special interest in advanced minimally invasive endoscopic techniques such as endoscopic submucosal dissection (ESD), peroral endoscopic myotomy (POEM) and endoscopic suturing and their applications in the resection of cancerous and pre-cancerous lesions of the GI tract as well as in the management of achalasia, gastroparesis, obesity and gastroesophageal reflux disease (GERD).

Alexandra Guillaume, MD, Director, Gastrointestinal Motility Center; Assistant Professor, Department of Medicine
Dr. Guillaume is a board-certified gastroenterologist with expertise in motility disorders of the gastrointestinal tract. She leads the Stony Brook University Hospital Gastrointestinal Motility Center which specializes in the diagnosis and management of feeding and swallowing disorders as well as luminal motility disorders involving diarrhea and/or constipation, refractory GERD, irritable bowel syndrome and small intestinal bacterial overgrowth. Under the leadership of Dr. Guillaume, the motility center provides high resolution esophageal and anorectal manometry, esophageal pH testing, hydrogen breath tests, as well as Smart Pill.

Dr. Guillaume graduated from the Tufts University School of Medicine. She then completed Internal Medicine residency at New York University Medical Center prior to joining the GI fellowship program at Stony Brook University Hospital. She also has additional fellowship training in the management of enteral and parenteral nutrition from NY Presbyterian Hospital - Columbia University Medical Center.

Chris E. Lascarides, MD, Associate Professor, Department of Medicine, Director, Outpatient Facility
Dr. Lascarides is a board-certified gastroenterologist with expertise in gastroesophageal reflux disease (GERD), Barrett’s esophagus, colon cancer screening, esophageal and gastric screening, difficult to remove colonic polyps, celiac disease, diverticulitis and diverticulosis. He is an Associate Professor of Medicine, Division of Gastroenterology and Hepatology, at Stony Brook School of Medicine.

Ellen Li, MD, PhD, Director of GI Translational Research
Dr. Li is a board-certified gastroenterologist and world-class scientist with expertise in inflammatory bowel diseases (IBD). Her specialty as a scientist is in translational research, which focuses on taking scientific discoveries and translating them into ways to help improve people’s health. In Stony Brook’s Division of Gastroenterology and Hepatology, she leads a major translational research initiative to analyze the effects of two key genes on the microscopic bacteria (microbia) that are present in the lining of the intestines and to explore how these microbia interact with the lining in the gut. Dr. Li is a Professor of Medicine and Molecular Genetics and Microbiology, Division of Gastroenterology and Hepatology, at Stony Brook School of Medicine.

Farah Monzur, MD, Assistant Professor, Department of Medicine, IBD Specialist, Associate Program Director GI Fellowship
Dr. Monzur is a board-certified gastroenterologist and hepatologist with expertise in Crohn’s disease and ulcerative colitis. She completed her undergraduate and medical school training as a part of the joint 7-year Accelerated BS/MD program between Rensselaer Polytechnic Institute and Albany Medical College. Subsequently, she went to Georgetown University Hospital for internal medicine residency. She then finished her gastroenterology fellowship at Stony Brook University Hospital.

Dr. Monzur currently is an Assistant Professor of Clinical Medicine at the Division of Gastroenterology and Hepatology. She is the Associate Program Director for the gastroenterology fellowship and is a part of the Master Educator Fellowship Program at Stony Brook University. Dr. Monzur specializes in treating patients with inflammatory bowel disease (IBD), celiac disease, eosinophilic esophagitis, lymphocytic colitis, collagenous colitis, diverticulitis, gastroesophageal reflux disease (GERD), Barrett’s esophagus, peptic ulcer disease, irritable bowel syndrome (IBS), gastrointestinal bleeding, and colon cancer screening. She performs upper endoscopy, colonoscopy, chromoendoscopy, and wireless capsule endoscopy.

Bradley Morganstern, MD, Assistant Professor, Department of Medicine, IBD Specialist
Dr. Morganstern is a graduate of Dartmouth College and obtained his medical degree from Emory University School of Medicine. He trained in internal medicine at The Mount Sinai Hospital followed by a gastroenterology fellowship at Stony Brook University Hospital and an advanced fellowship in inflammatory bowel diseases at Cedars-Sinai Medical Center.

Dr. Morganstern’s practice encompasses all facets of general gastroenterology including gastroesophageal reflux disease (GERD), peptic ulcer disease, chronic constipation and irritable bowel syndrome (IBS), with additional expertise in inflammatory bowel diseases including Crohn’s disease and ulcerative colitis. Dr. Morganstern serves on the Medical Advisory Committee for the Crohn’s and Colitis Foundation of America Greater New York Chapter. He was named as a 2017 Super Doctors® Rising Star and was named by Healio Gastroenterology to the Healio Gastroenterology 200 as a leading innovator in the field of medical and surgical gastroenterology and hepatology.

Ramona Rajapakse, MD, Director of the IBD Center, Division of Gastroenterology and Hepatology
Dr. Rajapakse is board-certified in gastroenterology and hepatology, with expertise in inflammatory bowel disease (IBD), which includes Crohn’s disease and ulcerative colitis. She also has a special interest and advanced training in fertility and pregnancy in IBD. Additionally, Dr. Rajapakse is an expert in colon cancer screening, gastroesophageal reflux disease (GERD), irritable bowel syndrome (IBS) and gastrointestinal bleeding. She is an Associate Professor of Clinical Medicine, Division of Gastroenterology and Hepatology, at Stony Brook School of Medicine. For more information, visit the Inflammatory Bowel Disease Center.

Edward Sun, MDAssistant Professor, Department of Medicine
Edward Sun, MD is a Clinical Assistant Professor of Medicine at Stony Brook University Medical Center in the Division of Gastroenterology & Hepatology. Dr. Sun is Board Certified in Internal medicine and completed his Gastroenterology Fellowship at Stony Brook Medical Center. He is a practicing Gastroenterologist at both Stony Brook Medical Center and at the Northport Veterans Affairs Medical Center. At Stony Brook, Dr. Sun has thrived in his role as a Gastroenterology Hospitalist caring for acutely-ill patients with GI disorders on the Inpatient service. Dr. Sun specializes in treating patients with upper and lower GI bleeding, abdominal pain, dysphagia, diarrhea, and acute liver injury.

In addition to his clinical responsibilities, Dr. Sun is involved in research aiming to improve Patient Quality and Access to care. He is an active member of the American Society for Gastrointestinal Endoscopy (ASGE), having served on the ASGE Reimbursement Committee since May, 2015. The focus of this National Committee has been on physician and facility reimbursement, coding, and new payment delivery models. Dr. Sun is a member of the ASGE MACRA Implementation Workgroup, providing expertise and analysis of CMS (Centers for Medicare and Medicaid Services) proposals on MACRA (Medicare Access and CHIP Reauthorization Act) implementation with particular attention to the Quality Payment Program (QPP) and proposed episodes of care. He was nominated and selected to represent the ASGE as a member of the CMS Clinical Subcommittee on Gastrointestinal Disease Management and as the ASGE liaison for the Links of Care National Colorectal Cancer Round Table established by the American Cancer Society. As of this professional update, Dr. Sun is completing his second year of business school at Wharton’s Executive MBA program at the University of Pennsylvania.

Demetrios Tzimas, MD, Assistant Professor, Department of Medicine
Dr. Demetrios Tzimas completed both his Internal Medicine Residency and Gastroenterology Fellowship at the NYU School of Medicine, where he was awarded the distinction of both Resident and Gastroenterology Fellow of the Year. He completed a one year Advanced and Therapeutic Endoscopy Fellowship at Stony Brook University Hospital, where he was awarded with the honor of Fellow Educator of the Year. Dr. Tzimas is Board Certified in both Internal Medicine and Gastroenterology. He specializes in ERCP, EUS, and enteral stenting. Dr. Tzimas also performs device assisted enteroscopy and altered anatomy ERCP. He is a member of the Advanced and Therapeutic Endoscopy Service in the Division of Gastroenterology and Hepatology. He is currently the course director of the Stony Brook University School of Medicine's Gastroenterology Course for second year medical students.

Vincent W. Yang, MD, PhD, Professor and Simons Chair, Department of Medicine
Dr. Yang received his gastroenterology fellowship training at the Johns Hopkins Hospital and has close to 25 years of experience in practicing gastroenterology. Prior to joining Stony Brook, Dr. Yang was Director of the Division of Digestive Diseases at Emory University in Atlanta, Georgia. Dr. Yang is an internationally renowned physician scientist with a special interest in the causes, treatment and prevention of colon cancer. Clinically he specializes in treating patients with hereditary (inherited) forms of colon cancer or polyps, including familial adenomatous polyposis (FAP) and Lynch syndrome. He also sees patients with general gastrointestinal conditions, including inflammatory bowel disease, esophageal reflux and chronic diarrheal diseases as well as provides screening tests for colon cancer.