title: Ammonium metabolism and protection from urease mediated destruction in Helicobacter pylori infection.
abstract: OBJECTIVE
  To investigate further the intracellular ammonium metabolism of Helicobacter pylori and the mechanism of its urease mediated destruction.
  
  
  METHODS
  The mechanism of the in vitro destruction of H pylori was investigated by incubating it in buffer solutions, at pH 6.0, containing isocitrate or alpha ketoglutarate in addition to urea concentrations which had previously been shown to destroy H pylori.
  
  
  RESULTS
  The median (range) 5 minute survival of H pylori in 0.2 mol/l citrate buffer (pH 6.0) in the absence of urea was 88% (18-184%) and was similar to its survival in 0.2 mol/l isocitrate buffer in the absence of urea, median 88% (15-274%). In the presence of 50 mmol/l urea the survival of H pylori in the citrate buffer was reduced, 9.9% (0-146%), compared with its survival in isocitrate buffer with the same concentration of urea 37% (0-274%) (p < 0.01). A 72 hour preincubation of the organism with 10 mmol/l alpha ketoglutarate also increased the 5 minute survival of the organism in 0.2 mol/l citrate buffer containing 50 mmol/l urea to 36% (9-145%) compared with its survival in the same buffer but without preincubation with alpha ketoglutarate 0% (0-62%).
  
  
  CONCLUSIONS
  The protection of H pylori from rapid destruction by the supply of compounds used in the intracellular metabolism of the ammonium shows that the urease mediated destruction of H pylori can be explained by intracellular depletion of alpha ketoglutarate as a result of over production of ammonium by uncontrolled urease activity.
authors.affiliation: Department of Chemical Pathology, Wirral Hospital NHS Trust.
authors.forename: W D
authors.initials: WD
authors.lastname: Neithercut
authors.forename: C
authors.initials: C
authors.lastname: Williams
authors.forename: M S
authors.initials: MS
authors.lastname: Hossack
authors.forename: K E
authors.initials: KE
authors.lastname: McColl
mesh_terms: D000641:Ammonia / Q000378:metabolism*; D002951:Citrates / Q000494:pharmacology; D019343:Citric Acid; D016481:Helicobacter Infections / Q000378:metabolism*; D016480:Helicobacter pylori / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism* / Q000502:physiology; D006801:Humans; D007523:Isocitrates / Q000494:pharmacology*; D007656:Ketoglutaric Acids / Q000494:pharmacology*; D014508:Urea / Q000494:pharmacology; D014510:Urease / Q000502:physiology*
chemical_list: D002951:Citrates; D007523:Isocitrates; D007656:Ketoglutaric Acids; D019343:Citric Acid; D000641:Ammonia; D014508:Urea; C034219:isocitric acid; D014510:Urease