title: Evidence that oxidative stress is increased in plasma from patients with maple syrup urine disease.
abstract: Maple syrup urine disease (MSUD) or branched-chain alpha-keto aciduria (BCKA) is an inherited disorder caused by a deficiency of the branched-chain alpha-keto acid dehydrogenase complex (BCKAD) activity. The blockage of this pathway leads to tissue accumulation of the branched-chain amino acids (BCAA) leucine, isoleucine and valine and their respective keto-acids. The clinical features presented by MSUD patients include ketoacidosis, convulsions, coma, psychomotor delay and mental retardation. The mechanism of brain damage in this disease is still poorly understood. However, an increase in lipid peroxidation in vitro in cerebral cortex of young rats as well as a decrease in the antioxidant defenses has been previously observed. In the present work we evaluated different oxidative stress parameters, named reactive species of thiobarbituric acid (TBARS), total antioxidant reactivity (TAR) and total antioxidant status (TAS) in plasma of MSUD patients in order to evaluate whether oxidative stress is involved in this disorder. We verified a marked increase of plasma TBARS measurements, which is indicative of increased lipid peroxidation, as well as a decrease on plasma TAR reflecting a deficient capacity to efficiently modulate the damage associated with an increased production of reactive species. In contrast, TAS was not changed indicating that the total content of antioxidants in plasma of patients affected by MSUD was not altered. These results suggest that free radical generation is elicited in MSUD and is possibly involved in the pathophysiology of the tissue damage found in this disorder.
authors.affiliation: Departamento de Bioquímica, Instituto de Ciências Básicas da Saúde, Universidade Federal do Rio Grande do Sul, Porto Alegre, RS, Brazil.
authors.forename: Alethéa G
authors.initials: AG
authors.lastname: Barschak
authors.forename: Angela
authors.initials: A
authors.lastname: Sitta
authors.forename: Marion
authors.initials: M
authors.lastname: Deon
authors.forename: Marcella H
authors.initials: MH
authors.lastname: de Oliveira
authors.forename: Alexsandro
authors.initials: A
authors.lastname: Haeser
authors.forename: Carlos S
authors.initials: CS
authors.lastname: Dutra-Filho
authors.forename: Moacir
authors.initials: M
authors.lastname: Wajner
authors.forename: Carmen R
authors.initials: CR
authors.lastname: Vargas
mesh_terms: D000975:Antioxidants / Q000378:metabolism*; D001798:Blood Proteins / Q000378:metabolism; D005609:Free Radicals / Q000097:blood; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D015227:Lipid Peroxidation; D008375:Maple Syrup Urine Disease / Q000378:metabolism*; D018384:Oxidative Stress; D017392:Thiobarbituric Acid Reactive Substances / Q000378:metabolism
chemical_list: D000975:Antioxidants; D001798:Blood Proteins; D005609:Free Radicals; D017392:Thiobarbituric Acid Reactive Substances