[Future for basic and clinical studies on peptic ulcer disease]

Since the discovery of H. pylori, various causes of peptic ulcer disease is reevaluated, and only four factors are now considered most important; H. pylori infection, gastric acid, NSAID administration, and mental and physical stress. Among them, gastric acid is an aggravating factor, and gastric acid alone can hardly develop peptic ulcers. The relationship between H. pylori infection and stress has been studied at Hanshin-Awaji great earthquake occurred in 1995. Immediately after the earthquake, the number of patients with peptic ulcer disease has been greatly increased, and those patients were considered to be typical cases of stress ulcers. Interestingly, however, it was found that 83.2% of the patients were infected with H. pylori. The data suggested that stress ulcer developed in those infected with H. pylori. In contrast, the relationship between H. pylori infection and NSAID in the development of ulcer disease is more complex. It is still unclear whether H. pylori infection is an additive effect for development of peptic ulcer disease by NSAID administration or not.