{"id":"70813255-33cb-512e-982d-b4608fd7a944","stable_key":"7fc92b9e-9cbf-556e-8719-6b5244625250:b12-nitrous-oxide-serum-function-discordance","predicate":"normal_value_coexisted_with_abnormal_dna_synthesis_assay","statement":"Serum B12 remained normal despite the abnormal marrow dU suppression pattern; three of nine surgery-only nitrous oxide recipients also had abnormal assays at 24 hours.","claim_class":"observational","status":"source_derived_draft","evidence_grade":"ungraded","direction":"context_dependent","is_public":true,"mechanism_event_id":"02ea0ba8-c03d-54a7-a603-026f73c4a81a","mechanism_event_label":"A normal amount measured in serum did not establish normal intracellular function under this exposure.","subject":{"id":"8390898f-7915-5c30-8ada-c416a386f5f3","slug":"serum-cobalamin-concentration","display_name":"Serum cobalamin concentration","entity_type_key":"cellular_process"},"object":{"id":"e4eb7b08-dbef-5923-aa11-4e76c63bb482","slug":"deoxyuridine-suppression-assay","display_name":"Deoxyuridine suppression assay","entity_type_key":"cellular_process"},"evidence_count":1,"mechanism_event":{"id":"02ea0ba8-c03d-54a7-a603-026f73c4a81a","stable_key":"7fc92b9e-9cbf-556e-8719-6b5244625250:b12-nitrous-oxide-serum-function-discordance-event","event_type":"observed_intervention","label":"A normal amount measured in serum did not establish normal intracellular function under this exposure.","description":"Serum B12 remained normal despite the abnormal marrow dU suppression pattern; three of nine surgery-only nitrous oxide recipients also had abnormal assays at 24 hours.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"e2fe2626-86ee-54bf-b85c-540ef5567fde","slug":"nitrous-oxide","display_name":"Nitrous oxide","entity_type_key":"small_molecule"},"role":"exposure","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"8390898f-7915-5c30-8ada-c416a386f5f3","slug":"serum-cobalamin-concentration","display_name":"Serum cobalamin concentration","entity_type_key":"cellular_process"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"e4eb7b08-dbef-5923-aa11-4e76c63bb482","slug":"deoxyuridine-suppression-assay","display_name":"Deoxyuridine suppression assay","entity_type_key":"cellular_process"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""}]},"contexts":[{"dimension":"availability_state","value_text":"machinery_impairment","comparator":null,"unit":null,"notes":"Imported condition classification; unverified.","entity":null},{"dimension":"experimental_model","value_text":"Prospective perioperative study in 22 patients undergoing cardiac bypass surgery.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"exposure","value_text":"Nitrous oxide/oxygen for 24 hours, during surgery only, or no nitrous oxide; marrow morphology and deoxyuridine suppression assays.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"The assay is an indirect functional test, not a direct methionine-synthase rate measurement.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Vitamin B12 research collection; topical membership is not evidence of a direct dietary effect.","comparator":null,"unit":null,"notes":"","entity":{"slug":"vitamin-b12","display_name":"Vitamin B12 (cobalamins)","entity_type_key":"chemical_species"}},{"dimension":"organism","value_text":"Homo sapiens","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"A normal amount measured in serum did not establish normal intracellular function under this exposure.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[b12-amess1978] Megaloblastic haemopoiesis in patients receiving nitrous oxide (1978). https://pubmed.ncbi.nlm.nih.gov/79709/ DOI: 10.1016/s0140-6736(78)92941-0","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"Human bone marrow and serum","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"trigger_kind","value_text":"machinery_impairment","comparator":null,"unit":null,"notes":"Imported condition classification; unverified.","entity":null}],"evidence":[{"id":"6f686b9c-cb85-5ab6-99c1-e203b5d46e6f","evidence_kind":"source_excerpt","locator":"Lines 1722-1732","start_line":1722,"end_line":1732,"excerpt":"### b12-nitrous-oxide-serum-function-discordance\nSerum B12 remained normal despite the abnormal marrow dU suppression pattern; three of nine surgery-only nitrous oxide recipients also had abnormal assays at 24 hours.\nCondition category: machinery_impairment\nnutrient_topic: Vitamin B12 research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: A normal amount measured in serum did not establish normal intracellular function under this exposure.\norganism: Homo sapiens\ntissue_or_cell_type: Human bone marrow and serum\nexperimental_model: Prospective perioperative study in 22 patients undergoing cardiac bypass surgery.\nlimitations: The assay is an indirect functional test, not a direct methionine-synthase rate measurement.\nexposure: Nitrous oxide/oxygen for 24 hours, during surgery only, or no nitrous oxide; marrow morphology and deoxyuridine suppression assays.\n[b12-amess1978] Megaloblastic haemopoiesis in patients receiving nitrous oxide (1978). https://pubmed.ncbi.nlm.nih.gov/79709/ DOI: 10.1016/s0140-6736(78)92941-0","model_system":"Prospective perioperative study in 22 patients undergoing cardiac bypass surgery.","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [b12-amess1978] Megaloblastic haemopoiesis in patients receiving nitrous oxide (1978). https://pubmed.ncbi.nlm.nih.gov/79709/ DOI: 10.1016/s0140-6736(78)92941-0","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"73145023-2982-5848-aff2-8d8875d6b9c5","stable_key":"import-7fc92b9e-9cbf-556e-8719-6b5244625250","title":"Vitamin B12: mechanisms, deficiency and nutrient interactions (2026-09-17)","document_type":"imported_text","citation_label":"AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text.","file_path":"","sha256":"ad5b3a51d36e856aa7fdfd1cc23f690b094689bad87d28e1a621a54675a01c92","revision_id":"118bd616-0c13-549f-bfeb-bc439715b89c","review_status":"unverified_draft","notes":""}}],"relations":[],"conflicts":[],"corrections":[],"research":null}