title: Helicobacter pylori infection prevents nocturnal gastric acid breakthrough.
abstract: OBJECTIVE
  Nocturnal gastric acid breakthrough (NAB) is given attention as one of the factors that cause refractory reflux esophagitis. However, its clinical states and mechanisms are not yet clearly understood. We studied whether there will be a NAB outbreak or not among healthy Japanese male volunteers upon administration of omeprazole, as well as what kind of factors will be involved in case of an outbreak.
  
  
  METHODS
  Twenty-one volunteers were selected as subjects for this research. Subjects were checked for symptoms as well as for esophageal hiatal hernia, atrophic patterns and Helicobacter pylori infection of the gastric mucosa. We also conducted esophageal and gastric 24h pH monitoring twice before and after administration of 20mg omeprazole. We further studied CYP2C19 gene polymorphism.
  
  
  RESULTS
  We observed NAB outbreak in 9 cases (42.9%) among 21 subjects. All 6 cases (100%) in the H. pylori-positive group showed NAB negative while 6 (40%) of the 15 cases in the H. pylori-negative group showed NAB negative. We found a statistically significant difference between these two groups (P=0.012). We also found a tendency that NAB outbreak is affected by CYP2C19 gene polymorphism.
  
  
  CONCLUSIONS
  H. pylori infection prevents NAB among healthy Japanese male volunteers under administration of omeprazole.
authors.affiliation: Department of Gastroenterology and Hepatology, Yamaguchi University School of Medicine, Japan.
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Saiki
authors.forename: Tomoharu
authors.initials: T
authors.lastname: Yoshida
authors.forename: Yukari
authors.initials: Y
authors.lastname: Tanioka
authors.forename: Tomohito
authors.initials: T
authors.lastname: Yagawa
authors.forename: Toshiya
authors.initials: T
authors.lastname: Harada
authors.forename: Tadashi
authors.initials: T
authors.lastname: Okazawa
authors.forename: Kiwamu
authors.initials: K
authors.lastname: Okita
mesh_terms: D000328:Adult; D001189:Aryl Hydrocarbon Hydroxylases / Q000235:genetics; D065731:Cytochrome P-450 CYP2C19; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005744:Gastric Acid; D016481:Helicobacter Infections / Q000235:genetics / Q000503:physiopathology*; D016480:Helicobacter pylori; D006801:Humans; D008297:Male; D008875:Middle Aged; D006899:Mixed Function Oxygenases / Q000235:genetics; D009853:Omeprazole / Q000494:pharmacology; D011110:Polymorphism, Genetic
chemical_list: D004791:Enzyme Inhibitors; D006899:Mixed Function Oxygenases; D001189:Aryl Hydrocarbon Hydroxylases; C045793:CYP2C19 protein, human; D065731:Cytochrome P-450 CYP2C19; D009853:Omeprazole