Involvement of reactive oxygen species in gastric ulceration: protection by melatonin.

Uncontrolled hydrochloric acid secretion and ulceration in the stomach due to various factors are serious global problems today. Although the mechanism of acid secretion from the parietal cell is now fairly known, the mechanism of gastric ulceration is still not clear today. Among various causes of gastric ulceration, lesions caused by stress, alcohol consumption, Helicobacter pylori infection and use of nonsteroidal antiinflammatory drugs have been shown to be mediated largely through the generation of reactive oxygen species especially hydroxyl radical (*OH). A number of excellent drugs have been proved useful in controlling hyperacidity and ulceration but their long term uses are not devoid of disturbing side-effects. Hence, the search is still on to find out a compound possessing antisecretory, antiulcer and antioxidant properties which will serve as a powerful therapeutic agent to cure gastric hyperacidity and ulcer. This article describes the role of reactive oxygen species in gastric ulceration, drugs controlling them with their merits and demerits and, the role of melatonin, a pineal hormone in protecting the gastric lesions with a final commentary on how melatonin research with respect to gastric pathophysiology can be taken forward with a view to projecting this indole as a promising therapeutic agent to control gastric ulceration in humans.

Biochemical studies on the origin of the ATPase of the avian myeloblastosis virus.

The adenosine triphosphatase activity of the avian myeloblastosis virus obtained from the blood of the virus-infected chicken was compared with that of the host cell myeloblasts. The specific activity of the viral enzyme is unusually higher than that of the myeloblasts. A significant difference in inhibitor sensitivity was observed with quercetin. When the virus was grown in chicken embryonic fibroblasts in culture, the resulting virus showed very little adenosine triphosphatase activity, comparable to that of the fibroblasts and similar sensitivity to inhibitors. Antibody raised against the purified enzyme of avian myeloblastosis virus inhibits the enzyme activity of the myeloblasts while the activity of the fibroblasts enzyme as well as that of fibroblast-grown virus remains unaffected.