GastritisGastritis, AtrophicHelicobacter pyloriGastric MucosaHelicobacter InfectionsPyloric AntrumGastritis, HypertrophicMetaplasiaStomachGastroscopyPepsinogen AStomach NeoplasmsAchlorhydriaBile RefluxStomach UlcerGastrinsPeptic UlcerPepsinogen CStomach DiseasesDuodenal UlcerChronic DiseaseHelicobacter felisHelicobacter heilmanniiParietal Cells, GastricDuodenitisAnemia, PerniciousBiopsyDyspepsiaHelicobacterUreasePepsinogensPostgastrectomy SyndromesGastric JuiceEndoscopy, GastrointestinalPrecancerous ConditionsCampylobacterEndoscopyAtrophyAcinonyxAnti-Ulcer AgentsAntigens, BacterialGastric AcidH(+)-K(+)-Exchanging ATPaseAmoxicillinAutoimmune DiseasesAntibodies, BacterialOmeprazoleDuodenogastric RefluxGastric FundusEndoscopy, Digestive SystemGastroenterostomyIntrinsic FactorBacterial ProteinsCampylobacter InfectionsGastric Acidity DeterminationBismuthThymectomyEsophagitisAntacidsGastrointestinal DiseasesLymphocytosisGastroesophageal RefluxGastrin-Secreting Cells