DuodenitisCeliac DiseaseGlutensGliadinDiet, Gluten-FreeDuodenumIntestinal MucosaJejunumDuodenoscopyDuodenal UlcerDuodenal DiseasesTransglutaminasesReticulinHemadsorption Inhibition TestsBiopsyEnzyme TherapyImmunoglobulin AProlaminsGastritisAvena sativaMetaplasiaIgA DeficiencyIntestine, SmallHLA-DQ AntigensCimetidineHelicobacter InfectionsAutoantibodiesTriticumHelicobacter pyloriDiet, Protein-RestrictedPlasma CellsAtrophyDyspepsiaPyloric Antrum