Document Detail


Further evidence of the toxic effect of ammonia produced by Helicobacter pylori urease on human epithelial cells.
MedLine Citation:
PMID:  1563774     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Former studies have shown that Helicobacter pylori can induce vacuolation of vacuolation of epithelial cells in vitro and possibly in vivo, either by direct action of a cytotoxin or by the action of its strong urease, which breaks down the urea physiologically present in the stomach into cytotoxic ammonia. We have developed a test using HEp2 cells with adherent H. pylori bacteria in order to compare the effects of an H. pylori urease-negative variant with those of its urease-positive parent strain in the presence of 10 mM urea. The level of ammonia production as well as cell vacuolation and viability were monitored for 72 h. The ammonia produced (20 mM) was found to be the essential determinant of the degree of cell vacuolation and viability of HEp2 cells. However, the addition of acetohydroxamic acid (200 mg/liter), a potent urease inhibitor which inhibits ammonia production, did not completely restore cell growth, suggesting the difficulty of neutralizing the ammonia in the vicinity of the cells. Antibodies directed against H. pylori did not neutralize the urease activity. When H. mustelae was tested in the same manner, the detrimental effects were not observed because a lower quantity of ammonia (5 mM) was generated. This was due to a lower urease activity, although the adherence properties of H. mustelae were different from those of H. pylori both quantitatively (greater adherence) and qualitatively (localized instead of diffuse adherence). We conclude that H. pylori-induced ammonia is an essential determinant of its cell toxicity as well as its adherence properties, which allow a high concentration of ammonia at the cellular level.
Authors:
F Mégraud; V Neman-Simha; D Brügmann
Related Documents :
6158454 - Differential reactivity of isolated mast cells from the rat and guinea pig.
9759944 - Hyperplasia of gastric antral beta-microseminoprotein endocrine-like cells and increase...
22358754 - Improved protocols for the isolation and in-situ cryopreservation of cell colonies.
20709804 - The transcription factor mist1 is a novel human gastric chief cell marker whose express...
2323024 - Cell attachment and neurite stability in ng108-15 cells: effects of 5'-deoxy, 5'-methyl...
14704484 - Dual action of cyclin-dependent kinase inhibitors: induction of cell cycle arrest and a...
Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Infection and immunity     Volume:  60     ISSN:  0019-9567     ISO Abbreviation:  Infect. Immun.     Publication Date:  1992 May 
Date Detail:
Created Date:  1992-05-19     Completed Date:  1992-05-19     Revised Date:  2010-09-07    
Medline Journal Info:
Nlm Unique ID:  0246127     Medline TA:  Infect Immun     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1858-63     Citation Subset:  IM    
Affiliation:
Laboratoire de Bactériologie Enfants, USN Tastet, Hopital Pellegzin, Bordeaux, France.
Export Citation:
APA/MLA Format     Download EndNote     Download BibTex
MeSH Terms
Descriptor/Qualifier:
Ammonia / toxicity*
Bacterial Adhesion
Cells, Cultured
Epithelium / drug effects
Helicobacter pylori / enzymology*
Humans
Urease / metabolism*
Chemical
Reg. No./Substance:
7664-41-7/Ammonia; EC 3.5.1.5/Urease
Comments/Corrections

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


Previous Document:  Heterogeneity of outer membrane proteins in Borrelia burgdorferi: comparison of osp operons of three...
Next Document:  Nucleotide sequence of the ospAB operon of a Borrelia burgdorferi strain expressing OspA but not Osp...