BARRY MARSHALL - ULCERS AND BACTERIA
Ulcers had been thought to be down to stress, personality, smoking, or genetics, and the only treatment was drugs to neutralise the acid.
But during the 1980s, two Australian researchers, Robin Warren and Barry Marshall, started to investigate another cause.
By the middle of 1982 they identified a bacterium called Helicobacter pylori (H.pylori) as the culprit, but peers thought living things could not survive the acidic conditions of the stomach.
Later - when they won a Nobel prize - Barry Marshall said: "No amount of logical reasoning could budge what people knew in their hearts to be true. Ulcers were caused by stress, bad diet, smoking, alcohol and susceptible genes. A bacterial cause was preposterous."
In frustration he decided to experiment on himself. He drank a broth containing H.pylori, and as he had expected, became ill.
After 10 days of vomiting and bad breath, he asked a colleague to look inside his stomach with an endoscope where he found the bacteria, as well as other symptoms which would lead to ulcers.
H.pylori had been proved to be the cause of ulcers. The researchers' paper was published in the Lancet in June 1984.
Warren and Marshall were awarded the Nobel Prize for Medicine in 2005.
Ulcers are now cured with a short course of antibiotics.