title: Homocysteine and cysteine loads in patients with homocystinuria due to cystathionine synthase deficiency: effects of vitamin B-6.
abstract: The metabolic response of patients with homocystinuria due to cystabhionine synthase deficiency to oral loads of homocysteine indicates: that even severely affected patients with homocystinuria have pools of cystine in their tissues; that control of sulfur amino acid metabolism favors increased concentrations of methionine rather than homocystine in the plasma; and that even patients who apparently are not B-6-responsive respond differently to the loads of homocysteine when challenged during B-6-treatment compared with their response before B-6 treatment. Loading tests with homocysteine indicate that B-6 treatment be of some benefit even in individuals who do not have an obvious biochemical response to such therapy.
mesh_terms: D003541:Cystathionine beta-Synthase / Q000172:deficiency*; D003545:Cysteine / Q000378:metabolism; D003553:Cystine / Q000097:blood; D003555:Cystinuria; D004220:Disulfides / Q000097:blood / Q000652:urine; D005260:Female; D006710:Homocysteine / Q000378:metabolism; D006711:Homocystine / Q000097:blood / Q000652:urine; D006712:Homocystinuria / Q000378:metabolism*; D006801:Humans; D006836:Hydro-Lyases / Q000172:deficiency*; D008297:Male; D011736:Pyridoxine / Q000494:pharmacology* / Q000627:therapeutic use; D013997:Time Factors
chemical_list: D004220:Disulfides; D006710:Homocysteine; D006711:Homocystine; D003553:Cystine; D006836:Hydro-Lyases; D003541:Cystathionine beta-Synthase; D003545:Cysteine; D011736:Pyridoxine