GastritisGastritis, AtrophicGefarnateParietal Cells, GastricH(+)-K(+)-Exchanging ATPaseMetaplasiaAutoimmune DiseasesThymectomyStomach UlcerGastric MucosaAnemia, PerniciousGastrointestinal HemorrhageHelicobacter pyloriHelicobacter InfectionsGastrinsAchlorhydriaStomachIntrinsic FactorAutoantibodiesPyloric AntrumMice, Inbred BALB CGastritis, HypertrophicAutoantigensLymphopeniaGastroscopyPepsinogen AStomach NeoplasmsBile RefluxPeptic UlcerPepsinogen CCD4-Positive T-LymphocytesStomach DiseasesDuodenal UlcerHelicobacter felisImmunoglobulin GHelicobacter heilmanniiT-Lymphocytes, RegulatoryChronic DiseaseDuodenitisDyspepsiaHelicobacterBiopsyUreasePepsinogensPostgastrectomy SyndromesGastric JuiceDisease Models, AnimalMice, Inbred C57BLPrecancerous ConditionsEndoscopy, GastrointestinalCampylobacter