For more than 30 years, I have participated in hundreds of clinical trials on antiviral therapy for viral hepatitis, including hepatitis B and C, and I have also led a number of them. These studies have remarkably improved our ability to treat people with these conditions, including the capacity to cure nearly all patients who have hepatitis C. I have authored and coauthored more than 250 scientific papers, chapters, and reviews on these and other topics. I continue to be involved in studies on viral hepatitis, and am also involved in studies examining treatments for other liver diseases, such as fatty liver disease and primary biliary cholangitis.

I am a fellow of several major organizations, including the American College of Physicians, the American Gastroenterological Association, the American Association for the Study of Liver Diseases, and the American College of Gastroenterology, and a member of the European Association for the Study of the Liver. Recently, I was honored to be elected to a fellowship at the Royal College of Physicians in the United Kingdom. I am a past president of the New York Society for Gastrointestinal Endoscopy and the New York Gastroenterological Association.