GastritisGastric MucosaGastritis, AtrophicHelicobacter pyloriHelicobacter InfectionsMetaplasiaPyloric AntrumStomach UlcerStomach NeoplasmsStomachChronic DiseasePepsinogen APeptic UlcerGastroscopyStomach DiseasesAchlorhydriaGastric JuiceGastrinsBiopsyDuodenal UlcerDyspepsiaBile RefluxPepsinogen CDuodenitisGastritis, HypertrophicHelicobacterHelicobacter heilmanniiUreaseIntestinal MucosaPrecancerous ConditionsHelicobacter felisParietal Cells, GastricCampylobacterAtrophyEndoscopy, GastrointestinalAnti-Ulcer AgentsAntigens, BacterialPepsinogensBacterial ProteinsAmoxicillinGastric AcidLymphoma, B-Cell, Marginal ZoneOmeprazoleMouth MucosaAnemia, PerniciousAntibodies, BacterialImmunohistochemistryCampylobacter InfectionsDuodenumH(+)-K(+)-Exchanging ATPaseLewis Blood-Group SystemPolymerase Chain ReactionClarithromycinPostgastrectomy SyndromesGastric FundusAdenocarcinomaCytotoxinsEndoscopyNasal MucosaGenotypeHyperplasiaChoristomaGastric MucinsIntestinesDuodenogastric RefluxEndoscopy, Digestive SystemIntrinsic FactorImmunoglobulin GMucous MembraneAcinonyxGastric Acidity DeterminationDNA, BacterialImmunoglobulin AAnti-Bacterial AgentsAutoimmune DiseasesCase-Control StudiesEpithelial CellsPrevalenceMicroscopy, ElectronDrug Therapy, CombinationRisk FactorsBismuthMexicoRetrospective StudiesGastrointestinal HemorrhageEnzyme-Linked Immunosorbent AssayGastrin-Secreting CellsGerbillinaeGene Rearrangement, B-Lymphocyte, Heavy ChainPentagastrinFollow-Up Studies