ulcers on wikipedia - Tobacco smoking, blood group, spices and other factors that were suspected to cause ulcers until late in the 20th century, are actually of relatively minor importance in the development of peptic ulcers.[1] A major causative factor (75% of gastric and 90% of duodenal ulcers) is chronic inflammation due to Helicobacter pylori, which appears spiral, but is not a spirochaete, rather a bacillus, that colonizes (i.e. settles there after entering the body) the antral mucosa. The immune system is unable to clear the infection, despite the appearance of antibodies. Thus, the bacterium can cause a chronic active gastritis (type B gastritis), resulting in a defect in the regulation of gastrin production by that part of the stomach, and gastrin secretion is increased. Gastrin, in turn, stimulates the production of gastric acid by parietal cells. The acid erodes the mucosa and causes the ulcer. Another major cause is the use of NSAIDs (see above). The gastric mucosa protects itself from gastric acid with a layer of mucous, the secretion of which is stimulated by certain prostaglandins. NSAIDs block the function of cyclooxygenase 1 (cox-1), which is essential for the production of these prostaglandins. Newer NSAIDs (celecoxib, rofecoxib) only inhibit cox-2, which is less essential in the gastric mucosa, and roughly halve the risk of NSAID-related gastric ulceration. Glucocorticoids lead to atrophy of all epithelial tissues. Their role in ulcerogenesis is relatively small. Stress in the psychological sense has not been proven to influence the development of peptic ulcers.[2] Burns and head trauma, however, can lead to 'stress ulcers', and it is reported in many patients who are on mechanical ventilation. Smoking leads to atherosclerosis and vascular spasms, causing vascular insufficiency and promoting the development of ulcers through ischemia. A family history is often present in duodenal ulcers, especially when blood group O is also present. Inheritance appears to be unimportant in gastric ulcers. Gastrinomas (Zollinger Ellison syndrome), rare gastrin secreting tumors, cause multiple and difficult to heal ulcers.