title: Oxidative stress in patients with obstructive sleep apnea syndrome.
abstract: OBJECTIVE
  We aimed to investigate whether systemic oxidative stress is increased in patients with obstructive sleep apnea syndrome (OSAS).
  
  
  METHODS
  A total of 18 patients with severe OSAS and 13 controls were included in the study. Inclusion criteria for OSAS patients were: snoring and apnea-hypopnea index (AHI) of >30 in full polysomnography, no previous treatment for OSAS, non-smoking status, and a medical history of being free of comorbidities known to increase oxidative stress. Controls were recruited among subjects assessed for snoring in the Sleep Laboratory Department if they had AHI<5. At baseline, patients were evaluated by the Epworth Sleepiness Scale and underwent spirometry, echocardiography, and full polysomnographic study. Blood samples were collected for evaluation of oxidative stress biomarkers [protein carbonyls, reduced (GSH) and oxidized (GSSG) glutathione, 8-isoprostane, thiobarbituric acid-reactive substances (TBARS), catalase activity, Cu-Zn superoxide dysmutase (SOD), total antioxidant capacity (TAC)] before and on the morning following polysomnography.
  
  
  RESULTS
  The overnight (morning-night) change (%) of GSH/GSSG ratio and GSH was significantly different between OSAS and controls (p = 0.03 and p = 0.048, respectively). Plasma protein carbonyls, erythrocyte catalase activity, 8-isoprostane, SOD, TBARS, and TAC plasma values were not different between OSAS and controls (p > 0.05). No significant correlation was found between changes in the levels of biomarkers and AHI, arousal, or desaturation index.
  
  
  CONCLUSIONS
  The present prospective investigation in a population free of comorbidities or factors which may increase systemic oxidative stress provides evidence that obstructive sleep apnea per se might be associated with increased oxidative burden possibly via GSH/GSSG pathway.
authors.affiliation: Department of Cardiology, University Hospital of Thessaly Biopolis, Larissa 41110, Greece.
authors.forename: Melpomeni
authors.initials: M
authors.lastname: Ntalapascha
authors.forename: Demosthenes
authors.initials: D
authors.lastname: Makris
authors.forename: Antonis
authors.initials: A
authors.lastname: Kyparos
authors.forename: Irene
authors.initials: I
authors.lastname: Tsilioni
authors.forename: Konstantinos
authors.initials: K
authors.lastname: Kostikas
authors.forename: Konstantinos
authors.initials: K
authors.lastname: Gourgoulianis
authors.forename: Dimitrios
authors.initials: D
authors.lastname: Kouretas
authors.forename: Epaminondas
authors.initials: E
authors.lastname: Zakynthinos
mesh_terms: D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000097:blood; D005260:Female; D005978:Glutathione / Q000097:blood; D019803:Glutathione Disulfide / Q000097:blood; D006801:Humans; D008297:Male; D008875:Middle Aged; D018384:Oxidative Stress / Q000502:physiology*; D017286:Polysomnography; D011446:Prospective Studies; D012016:Reference Values; D020181:Sleep Apnea, Obstructive / Q000175:diagnosis / Q000503:physiopathology*
chemical_list: D015415:Biomarkers; D005978:Glutathione; D019803:Glutathione Disulfide