b'Gastroenterologist Sekou Rawlins, MD, talks about colon cancer screening Gastroenterologist Sekou Rawlins, MD, talks about colon cancer screening. . Infectious disease expert Timothy Endy, MD, discusses deadly infections that may result from drug abuse Infectious disease expert Timothy Endy, MD, discusses deadly infections that may result from drug abuse. . Pediatric gastroenterologist Aamer Imdad, MBBS, explains the important role of vitamin A. Pediatric gastroenterologist Aamer Imdad, MBBS, explains the important role of vitamin A.'