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Cancer Letters, 65 (1992)15- 18 Elsevier Scientific Publishers
Ireland
Ltd.
Ammonia: a possible promotor carcinogenesis
in Helicobacter
pylori-related
gastric
Masahiko Tsujii, Sunao Kawano, Shingo Tsuji, Kouichi Nagano, Toshifumi Hayashi, Hideyuki Fusamoto, Takenobu Kamada and Kazuya Tamura
Ito, Nobuhiko
Department of Medicine, Osaka University Medical School and Division of Gastroenterology, l-1 -50 Fukushima, Fukushima-ku, Osaka (Japan)
National Hospital.
Osaka
(Received 26 November 1991) (Revision received 24 April 1992) (Accepted 27 April 1992)
Summary
Introduction
Helicobacter pylori (HP) has been shown to possibly
HP has
be a pathogen of gastric carcinoma. urease activity and produces ammonia
in the stomach. In this study, the role of ammonia on gastric carcinogenesis induced by Nmethyl-N’-nitro-N-nitrosoguanidine (MNNG) were investigated in rats. Afier 24 weeks pretreatment with MNNG (83 mg/f), 0.01% ammonia or tap water as a drinking water was administered for 24 weeks. The ammoniatreated rats showed a significantly higher incidence of gastric cancer (percent of animals with tumors and number of tumors per rat). Ammonia would thus appear to have an important role in HP-related human gastic carcinogenesis.
Keywords: Helicobacter pylori; ammonia; gastric cancer; atrophic gastritis Correspondence to: Masahiko Tsujii, Department of Medicine, Osaka University Medical School and Division of Gastroenterology, Osaka National Hospital, l-l-50 Fukushima, Fukushima-ku, Osaka, Japan.
0304-3835/92/$05.00
Printed
and Published
0
1992
in Ireland
Elsevier Scientific Publishers
Evidence is accumulating that HP infection plays a major contributory role in epidemic gastric cancer. The investigations examining the correlation between HP infection, as reflected in immunoglobulin G serum antibodies and risk of gastric cancer show that the differences in the infection patterns of HP by socioeconomical class are consistent with patterns of gastric cancer [12] and that the incidence of positive ELISA results was high in patients with gastric cancer [17]. These data suggest that most patients with gastric cancer have been infected with HP at some point in their life. Mechanisms for HP-related carcinogenesis in gastric mucosa are, however, not known. HP is recognized as having a major etiological role in type B chronic atrophic gastritis [8]. In pathogenesis of atrophic gastritis, continuous mucosal cell damage and acceleration of mucosal desquamation is thought to be involved, with consequent stimulation of cellular proliferation in the gastric mucosa, suggesting association with premalignancy [3,4]. As an etiologic factor in HP-related mucosal damage, increasing Ireland Ltd
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evidence has been collecting of ammonia produced by HP in the stomach. Ammonia concentration of gastric juice in HP-infected subjects is higher than in HP negative subjects (0.015% vs.