Marshall, Barry James (1951-…), an Australian physician, won the 2005 Nobel Prize in physiology or medicine for his discovery of the bacterium that causes peptic (digestive system) ulcers in human beings. He shared the prize with fellow Australian J. Robin Warren, a pathologist. The discoveries by the two scientists revolutionized the way that physicians treat peptic ulcers in patients.
Peptic ulcers develop in the stomach and the upper portion of the small intestine called the duodenum. During digestion and at certain other times, the stomachs of most people produce hydrochloric acid and an enzyme called pepsin. These powerful digestive juices can eat through the lining of the stomach and duodenum, causing an ulcer. In the past, most physicians believed that peptic ulcers were caused by stress and other factors that caused inappropriate secretion of digestive juices.
In 1982, Warren discovered an unknown bacterium in samples of stomach tissue from patients with peptic ulcers. He observed that this new type of bacterium, later named Helicobacter pylori, was associated with inflammation that occurs as peptic ulcers develop. Marshall and Warren conducted a study of 100 patients who suffered from peptic ulcers. The two scientists isolated the bacterium in most of the patients. Marshall succeeded in culturing (growing) the bacterium in the laboratory so that he and Warren could study it further. In a risky experiment, Marshall demonstrated that the bacterium caused illness by drinking a solution containing H. pylori. He developed severe gastritis (inflammation of the stomach), proving that the bacterium causes the inflammation that leads to peptic ulcers. In 1983, Warren and Marshall began to successfully treat ulcer patients. Today, physicians routinely treat, and can usually cure, ulcers with antibiotics that kill the Helicobacter bacterium.
Marshall was born in Kalgoorlie, Western Australia, on Sept. 30, 1951. He studied medicine at the University of Western Australia, graduating in 1974. He held positions at the Royal Perth Hospital in Australia from 1977 to 1986, and at the University of Virginia in the United States from 1986 to 1997. Since 1997, he has served as professor and research fellow at the University of Western Australia.
See also Ulcer ; Warren, J. Robin .
