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Prevalence rates and risk factors for H. pylori infection have been reported in many countries over the past year. Infection patterns in developed and developing countries are very different. Very high infection rates in developing countries with high incidence of gastric cancer were described, however, African enigma is still under controversy. The main risk factors for H. pylori infection are fecal-oral and oral-oral spread because H. pylori has not been detected to any extent in the environment. Recently, in childhood, main risk factors for transmission may be the contact with own father with H. pylori infection in Japan. Re-infection are very rare in adults, but not uncommon in childhood. Prevalence of H. pylori infection is reviewed.

Leukocytapheresis(LCAP) and Granulocytapheresis(GCAP) are classified as extracorporeal circulation therapy(ECCT). These therapies are a novel, effective way to treat patients with ulcerative colitis(UC). During 7 weeks of intensive therapy(LCAP weekly, predonisolone(PSL) 30-80 mg/day), UC patients treated with LCAP revealed significant improvements on their subjective and objective symptoms compared to patients treated with PSL intravenous administration. Moreover, LCAP has been recognized as safer than other drugs for UC. In our previous study, only 9.9% out of 1,978 LCAP sessions showed some side effects, and most were mild and temporary. Therefore, LCAP could be the first choice to treat UC patients who resist and/or reveal severe complications against ordinary drug therapies.

Twenty five years has passed since the re-discovery of Helicobacter pylori. Many people have studied on this organism since that time. Some mechanisms about gastric mucosal inflammation have been clarified, and pathogenesis of peptic ulcer formation and gastric cancer have been solved. H. pylori infection is related to chronic gastritis, peptic ulcer, gastric carcinoma, and MALToma. In 1998, it was reported that gastric cancer occurred in H. pylori infected mongolian gerbils. In Japan, the prevalence of peptic ulcer and gastric cancer is very high. Therefore, the treatment for H. pylori infection is necessary to prevent occurrence of these diseases. To treat H. pylori infection, various regimen have been tried. Triple therapy with PPI and two antibiotics is recommended for cure of H. pylori infection in European and US guidelines. Some guidelines for management of H. pylori infection and regimen were shown in this part.

The combination of a proton pump inhibitor with antibiotics has been accepted as an effective treatment for the eradication of Helicobacter pylori and the most rational regimen to cure peptic ulcers. Triple therapies including two antibiotics and a proton pump inhibitor achieves constant and high eradication rate. The one-week, low-dose triple regimen including metronidazole has been accepted in European countries, but the new triple therapy with proton pump inhibitor, amoxicillin and clarithromycin is recommended for treatment of H. pylori infection in Japan. Quadruple therapy with two antibiotics, bismuth and a proton pump inhibitor is a second-line therapy. Triple therapy with ranitidine bismuth and two antibiotics may be promising.

The prevalence of infection with H. pylori in developed countries was about 20%, on the other hand in developing countries it reached over 80%. In developed countries 40% of infants already had anti-H. pylori antibody and the prevalence of infection rapidly increased and then reached the peak (80%) in teenager. In contrast in developed countries the rate of infection with H. pylori was below 20% in teenager and gradually increased by age (1% per 1 year). In our country an unique pattern of the prevalence of infection with H. pylori was observed. The rate of infection with H. pylori in young person was low and increased with 1% per 1 year (developed countries pattern). However, middle-aged person had higher rate of infection of H. pylori (over 85%) (developing countries pattern). These results suggested H. pylori infection would be closely associated with childhood living conditions than current living (including socioeconomic) status. From this point of view, the prevention for infection with H. pylori in childhood will be most important to prevent the gastroduodenal disease related with H. pylori in the future.

Most of gastroduodenal diseases are associated with Helicobacter pylori infection. Cure of H. pylori infection may lead complete remission of recurrence of gastric and duodenal ulcer, and suppress the development of atrophic gastritis, gastric cancer and MALT lymphoma. H. pylori infection and hemorrhagic gastroduodenal diseases are reviewed.

Helicobacter pylori has been defined as a "definite carcinogen" at the WHO/IARC meeting in 1994. H. pylori causes histological gastritis. Long-lasting infection may induce atrophic gastritis, which is considered to be the first step in the gastritis-metaplasia-carcinoma sequence of the stomach. In a pooled analysis of the three prospective epidemiological studies, the relative risk for developing gastric cancer with H. pylori infection was 3.8, which was statistically significant. Thus, it was concluded that there was sufficient evidence in humans for the carcinogenicity of infection with H. pylori. However, there was no evidence experimentally for the carcinogenicity of infection with H. pylori. Further study is necessary to elucidate the role of H. pylori in gastric carcinogenesis.

It is now generally accepted that infection with Helicobacter pylori is the most common cause of active chronic gastritis and duodenal ulceration. Although H. pylori is detected in the majority of patients with gastric ulcer, its pathogenicity and role in gastric ulceration remains unclear. One method to study this relationship is to eradicate H. pylori and observe the recurrence of gastric ulcer. In the present paper we examined the consequence of H. pylori eradication by antibiotics mono therapy with histamine H2 receptor antagonist on the recurrence of gastric ulcer. Two cases treated with proton pump inhibitor plus clarithromycin were reported. It is concluded that eradication of H. pylori infection may diminish the recurrence of gastric ulcers.

Western blotting and ELISA techniques have been used to investigate antigen specificity of systemic responses. Immunoblotting studies demonstrate several major protein antigens that are detected most sera. H. pylori immunoblotting studies using rabbit hyperimmune sera identify several distinct strains. Seven monoclonal antibodies which are prepared in our laboratory recognize 33-35 kDa and 66 kDa of H. pylori. ELISA studies using the monoclonal antibody reveals considerable antigenic diversity among H. pylori strains. Serotyping of clinically isolated H. pylori Seems to be useful in clarifying the etiological roles of this bacteria. In spite of studies by several investigators, serotyping of H. pylori has not been established yet. Our studies suggest that H. pylori need to be further subdivided serologically.