{"id":"75ba2da7-20a9-578f-b881-dd7431f942a0","stable_key":"cb568d28-484a-5c2e-9fcc-2d780358e514:vc-enzyme-deficient-bb-response","predicate":"increases-estimated-synthesis-during-deficiency","statement":"Oral gamma-butyrobetaine increased urine-based estimated carnitine synthesis by 41–50 micromol/kg/day across ascorbate-replete, deficient and pair-fed guinea-pig groups; vitamin C deficiency did not abolish the precursor response.","claim_class":"observational","status":"source_derived_draft","evidence_grade":"ungraded","direction":"positive","is_public":true,"mechanism_event_id":"e4e383af-a2f0-5f02-9351-5a175c2da04c","mechanism_event_label":"Even vitamin-C-deficient animals could make substantial carnitine when given this precursor.","subject":{"id":"e83c0395-55f1-5483-9710-9b9aa9767689","slug":"gamma-butyrobetaine","display_name":"gamma-Butyrobetaine","entity_type_key":"small_molecule"},"object":{"id":"489dcb65-496a-5bdc-afaa-85d7883e55dc","slug":"guinea-pig-carnitine-synthesis-estimate","display_name":"Guinea-pig carnitine synthesis estimated from urinary output","entity_type_key":"cellular_process"},"evidence_count":1,"mechanism_event":{"id":"e4e383af-a2f0-5f02-9351-5a175c2da04c","stable_key":"cb568d28-484a-5c2e-9fcc-2d780358e514:vc-enzyme-deficient-bb-response-event","event_type":"observed_intervention","label":"Even vitamin-C-deficient animals could make substantial carnitine when given this precursor.","description":"Oral gamma-butyrobetaine increased urine-based estimated carnitine synthesis by 41–50 micromol/kg/day across ascorbate-replete, deficient and pair-fed guinea-pig groups; vitamin C deficiency did not abolish the precursor response.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"e83c0395-55f1-5483-9710-9b9aa9767689","slug":"gamma-butyrobetaine","display_name":"gamma-Butyrobetaine","entity_type_key":"small_molecule"},"role":"oral-precursor","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"da1a7137-08f2-5a36-8bb6-377fbd32e327","slug":"vitamin-c","display_name":"Vitamin C","entity_type_key":"chemical_species"},"role":"dietary-factor","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""},{"entity":{"id":"6e34c035-9371-578f-b799-fd2a14e9e40f","slug":"l-carnitine","display_name":"L-Carnitine","entity_type_key":"small_molecule"},"role":"product","stoichiometry":null,"state_label":"","sequence_order":2,"notes":""},{"entity":{"id":"489dcb65-496a-5bdc-afaa-85d7883e55dc","slug":"guinea-pig-carnitine-synthesis-estimate","display_name":"Guinea-pig carnitine synthesis estimated from urinary output","entity_type_key":"cellular_process"},"role":"readout","stoichiometry":null,"state_label":"","sequence_order":3,"notes":""}]},"contexts":[{"dimension":"availability_state","value_text":"nutrient_deficiency","comparator":null,"unit":null,"notes":"Imported condition classification; unverified.","entity":null},{"dimension":"cross_nutrient","value_text":"Vitamin C chemistry in collagen, modified-lysine/carnitine metabolism or copper-dependent peptide/catecholamine processing.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Guinea-pig dietary deficiency with pair feeding and precursor loading","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"exposure","value_text":"Vitamin C deficient diet for 28 days; oral trimethyllysine or gamma-butyrobetaine 0.5 mmol/kg/day on days 19–28, with replete and pair-fed controls.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"Estimate is derived from excretion during a large precursor load, not isotope-resolved basal flux; does not show all tissues are vitamin-C-independent.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Vitamin C research collection; topical membership is not evidence of a direct dietary effect.","comparator":null,"unit":null,"notes":"","entity":{"slug":"vitamin-c","display_name":"Vitamin C","entity_type_key":"chemical_species"}},{"dimension":"organism","value_text":"Cavia porcellus","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"Even vitamin-C-deficient animals could make substantial carnitine when given this precursor.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[carnitine1995] The ability of guinea pigs to synthesize carnitine at a normal rate from epsilon-N-trimethyllysine or gamma-butyrobetaine in vivo is not compromised by experimental vitamin C deficiency. (1995). https://pubmed.ncbi.nlm.nih.gov/7752911/ DOI: 10.1016/0026-0495(95)90120-5","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"Whole animal; urine-based synthesis estimate","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"trigger_kind","value_text":"nutrient_deficiency","comparator":null,"unit":null,"notes":"Imported condition classification; unverified.","entity":null}],"evidence":[{"id":"9dc179c3-b7e1-530d-896e-0cd0d59e2fa5","evidence_kind":"source_excerpt","locator":"Lines 767-778","start_line":767,"end_line":778,"excerpt":"### vc-enzyme-deficient-bb-response\nOral gamma-butyrobetaine increased urine-based estimated carnitine synthesis by 41–50 micromol/kg/day across ascorbate-replete, deficient and pair-fed guinea-pig groups; vitamin C deficiency did not abolish the precursor response.\nCondition category: nutrient_deficiency\nnutrient_topic: Vitamin C research collection; topical membership is not evidence of a direct dietary effect.\nplain_language: Even vitamin-C-deficient animals could make substantial carnitine when given this precursor.\norganism: Cavia porcellus\ntissue_or_cell_type: Whole animal; urine-based synthesis estimate\nexperimental_model: Guinea-pig dietary deficiency with pair feeding and precursor loading\nlimitations: Estimate is derived from excretion during a large precursor load, not isotope-resolved basal flux; does not show all tissues are vitamin-C-independent.\ncross_nutrient: Vitamin C chemistry in collagen, modified-lysine/carnitine metabolism or copper-dependent peptide/catecholamine processing.\nexposure: Vitamin C deficient diet for 28 days; oral trimethyllysine or gamma-butyrobetaine 0.5 mmol/kg/day on days 19–28, with replete and pair-fed controls.\n[carnitine1995] The ability of guinea pigs to synthesize carnitine at a normal rate from epsilon-N-trimethyllysine or gamma-butyrobetaine in vivo is not compromised by experimental vitamin C deficiency. (1995). https://pubmed.ncbi.nlm.nih.gov/7752911/ DOI: 10.1016/0026-0495(95)90120-5","model_system":"Guinea-pig dietary deficiency with pair feeding and precursor loading","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [carnitine1995] The ability of guinea pigs to synthesize carnitine at a normal rate from epsilon-N-trimethyllysine or gamma-butyrobetaine in vivo is not compromised by experimental vitamin C deficiency. 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