Helicobacter pyloriGastritisGastritis, AtrophicGastric MucosaHelicobacter InfectionsPyloric AntrumGastritis, HypertrophicMetaplasiaStomachGastroscopyPepsinogen AStomach NeoplasmsAchlorhydriaBile RefluxStomach UlcerGastrinsPeptic UlcerPepsinogen CStomach DiseasesDuodenal UlcerHelicobacter felisHelicobacter heilmanniiParietal Cells, GastricChronic DiseaseDuodenitisAnemia, PerniciousDyspepsiaHelicobacterBiopsyUreasePepsinogensPostgastrectomy SyndromesGastric JuicePrecancerous ConditionsEndoscopy, GastrointestinalCampylobacterAtrophyAcinonyxEndoscopyAnti-Ulcer AgentsAntigens, BacterialGastric AcidH(+)-K(+)-Exchanging ATPaseAmoxicillinAutoimmune DiseasesOmeprazoleDuodenogastric RefluxGastric FundusAntibodies, BacterialEndoscopy, Digestive SystemGastroenterostomyIntrinsic FactorGastric Acidity Determination