GastritisHelicobacter pyloriHelicobacter InfectionsGastritis, AtrophicGastric MucosaMetaplasiaChronic DiseaseStomach NeoplasmsPyloric AntrumStomachPeptic UlcerStomach UlcerPepsinogen ADyspepsiaDuodenal UlcerUreaseGastroscopyAchlorhydriaStomach DiseasesDuodenitisBiopsyPepsinogen CGastrinsHelicobacterGastric JuiceHelicobacter heilmanniiAmoxicillinBile RefluxCampylobacterBacterial ProteinsAnti-Ulcer AgentsEndoscopy, GastrointestinalHelicobacter felisClarithromycinPrecancerous ConditionsAtrophyOmeprazoleAntigens, BacterialAntibodies, BacterialGastritis, HypertrophicLymphoma, B-Cell, Marginal ZoneLewis Blood-Group SystemCampylobacter InfectionsCytotoxinsPylorusPolymerase Chain ReactionAnti-Bacterial AgentsMetronidazoleGenotypeDuodenumDNA, BacterialParietal Cells, GastricPepsinogensDrug Therapy, CombinationBismuthImmunoglobulin GAdenocarcinomaImmunohistochemistryIntestinesAnemia, PerniciousBreath TestsPrevalenceMexicoImmunoglobulin AGastric AcidGene Rearrangement, B-Lymphocyte, Heavy ChainCase-Control StudiesEnzyme-Linked Immunosorbent AssayLansoprazoleEndoscopyHyperplasiaPostgastrectomy SyndromesProton Pump InhibitorsEpithelial CellsGerbillinaePolymorphism, GeneticSensitivity and SpecificityInterleukin-1betaProspective StudiesEndoscopy, Digestive SystemAntacidsMolecular Sequence DataTinidazoleGastric FundusFollow-Up StudiesRisk FactorsH(+)-K(+)-Exchanging ATPaseAcinonyxGastric Acidity DeterminationRetrospective Studies