GastritisGastric MucosaGastritis, AtrophicHelicobacter pyloriHelicobacter InfectionsMetaplasiaPyloric AntrumStomach UlcerStomach NeoplasmsStomachChronic DiseasePepsinogen APeptic UlcerGastroscopyStomach DiseasesAchlorhydriaGastric JuiceGastrinsDuodenal UlcerBiopsyDyspepsiaBile RefluxPepsinogen CDuodenitisGastritis, HypertrophicHelicobacterHelicobacter heilmanniiUreaseIntestinal MucosaHelicobacter felisPrecancerous ConditionsParietal Cells, GastricCampylobacterAtrophyEndoscopy, GastrointestinalAnti-Ulcer AgentsAntigens, BacterialPepsinogensBacterial ProteinsAmoxicillinGastric AcidLymphoma, B-Cell, Marginal ZoneOmeprazoleMouth MucosaAnemia, PerniciousAntibodies, BacterialCampylobacter InfectionsDuodenumH(+)-K(+)-Exchanging ATPaseLewis Blood-Group SystemImmunohistochemistryClarithromycinPostgastrectomy SyndromesGastric FundusPolymerase Chain ReactionAdenocarcinomaCytotoxinsNasal MucosaEndoscopyGastric MucinsGenotypeIntestinesChoristomaDuodenogastric RefluxHyperplasiaEndoscopy, Digestive SystemIntrinsic FactorImmunoglobulin GAcinonyxGastric Acidity DeterminationMucous MembraneImmunoglobulin ADNA, BacterialAnti-Bacterial AgentsAutoimmune DiseasesEpithelial CellsCase-Control StudiesBismuthDrug Therapy, CombinationMexicoPrevalenceGastrin-Secreting CellsGerbillinaeGene Rearrangement, B-Lymphocyte, Heavy ChainPentagastrin