Warren, J. Robin (John Robin Warren), 1937–, Australian pathologist, grad. Univ. of Adelaide (M.B., B.S., 1961). He spent most of his career (1968–99) as a pathologist at the Royal Perth Hospital. Warren was a co-recipient, with Barry J. Marshall, of the 2005 Nobel Prize in physiology or medicine for their discovery of the bacterium Helicobacter pylori as the cause of gastric ulcers. Working as a pathologist, Warren had observed that these small, curved bacteria were always associated with an inflammation of the lining in the lower part of the stomach. By conducting a study of biopsied tissue, the pair determined that peptic ulcer disease is infectious and not induced by stress and lifestyle as previously was believed. Their discovery led to the treatment of peptic ulcers with antibiotics.