title: The plasma retinol levels as pro-oxidant/oxidant agents in haemodialysis patients.
abstract: BACKGROUND
  Oxidative stress is a process involved in haemodialysis-related pathologies such as cerebrovascular diseases. Retinol is the major circulating form of vitamin A and it is elevated in haemodialysis (HD) patients. It is known that these patients present anaemia that is not totally responsive to erythropoietin. The aim of this study was to evaluate the influence of plasma retinol levels on oxidative stress biomarkers, especially on delta-aminolevulinate dehydratase.
  
  
  METHODS
  Plasma retinol and malondialdehyde (MDA) levels were quantified by HPLC-UV/VIS; blood activities of catalase (CAT), superoxide dismutase (SOD) and delta-aminolevulinate dehydratase (ALA-D) were analysed by spectrophotometric methods, in HD patients (n = 29) and healthy subjects (n = 20).
  
  
  RESULTS
  The MDA and retinol levels, SOD and CAT activities were significantly increased in HD patients. ALA-D activity was significantly decreased. Retinol levels were correlated with MDA levels (r = 0.68), CAT (r = 0.39), SOD (r = 0.40) and ALA-D (r = -0.55). A partial correlation between retinol levels with ALA-D (r = 0.43), SOD (r = 0.30) and CAT (r = 0.36) activity was found, utilizing MDA levels as co-variable.
  
  
  CONCLUSIONS
  Higher retinol levels may be associated with the increase of SOD and CAT activities, but this increase was not sufficient to prevent the lipid peroxidation and ALA-D thiolic group oxidation. In this manner, our results could suggest that high retinol levels contribute as an additional factor to the oxidative tissue damage.
authors.affiliation: Center of Healthy Sciences, Laboratory of Toxicology, Department of Clinical and Toxicology Analysis, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil.
authors.forename: Miguel
authors.initials: M
authors.lastname: Roehrs
authors.forename: Juliana
authors.initials: J
authors.lastname: Valentini
authors.forename: Rachel
authors.initials: R
authors.lastname: Bulcão
authors.forename: José Cláudio
authors.initials: JC
authors.lastname: Moreira
authors.forename: Hanz
authors.initials: H
authors.lastname: Biesalski
authors.forename: Renata P
authors.initials: RP
authors.lastname: Limberger
authors.forename: Tilman
authors.initials: T
authors.lastname: Grune
authors.forename: Solange Cristina
authors.initials: SC
authors.lastname: Garcia
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D007676:Kidney Failure, Chronic / Q000097:blood* / Q000201:enzymology / Q000378:metabolism* / Q000628:therapy; D008297:Male; D008875:Middle Aged; D018384:Oxidative Stress; D006435:Renal Dialysis; D014801:Vitamin A / Q000097:blood*
chemical_list: D014801:Vitamin A