title: Levels of selected oxidative stress markers in the vitreous and serum of diabetic retinopathy patients.
abstract: OBJECTIVE
  In diabetes, an impaired antioxidant defense system contributes to the development of diabetic retinopathy. The main objective of this paper was to find correlations of oxidative stress parameters within and between the vitreous and serum in patients with type 2 diabetes who had developed proliferative diabetic retinopathy.
  
  
  METHODS
  The study included and compared two groups of patients who underwent vitrectomy: 37 patients with type 2 diabetes and proliferative retinopathy (PDR), and 50 patients with non-diabetic eye disorders (NDED). Vascular endothelial growth factor (VEGF), advanced oxidized protein product (AOPP), and oxidative stress markers (direct lipid hydroperoxidation (LPO), malondialdehyde (MDA), total superoxide dismutase (SOD), and glutathione (GSH)) were measured in the vitreous and serum of both groups and correlated with one another, between humoral compartments and with gender, age, and serum glucose levels.
  
  
  RESULTS
  In the vitreous of PDR patients, VEGF, LPO, and MDA (p<0.05) were increased and SOD values were slightly lowered (p<0.05) than in NDED patients. Vitreous AOPP and GSH showed no differences between the groups. In the serum, AOPP, MDA, and SOD were increased (p<0.05) and VEGF was slightly increased (p<0.05) in the PDR group compared to NDED. With regard to gender, similar changes were recorded for both groups, except for the lower serum MDA in males than females in the NDED group. Advanced age showed no significant effect on changes of measured parameters in the vitreous. In the serum, VEGF was positively correlated (p<0.05) and MDA and SOD negatively correlated (p<0.05) with increasing age. Among measured parameters within and between the vitreous and serum, several correlative links occurred in the PDR group that were not present in the NDED group. The most prominent correlation changes were between serum LPO and vitreal LPO, serum SOD and vitreal LPO, serum LPO and serum SOD, and vitreal VEGF and serum SOD.
  
  
  CONCLUSIONS
  Among the selected oxidative stress markers, SOD and LPO were highly correlative in both the vitreous and serum in PDR compared to patients without metabolic disorders. Their correlations suggested that monitoring their mutual alterations might be informative during PDR development and should be considered in further research.
authors.affiliation: Department of Ophthalmology, Sveti Duh Clinical Hospital, Sveti Duh 64, 10000 Zagreb, Croatia.
authors.forename: Vlatka
authors.initials: V
authors.lastname: Brzović-Šarić
authors.affiliation: Laboratory of Food Chemistry and Biochemistry, Faculty of Food Technology and Biotechnology, University of Zagreb, Zagreb, Croatia.
authors.forename: Irena
authors.initials: I
authors.lastname: Landeka
authors.affiliation: Department of Ophthalmology, Sveti Duh Clinical Hospital, Sveti Duh 64, 10000 Zagreb, Croatia.
authors.forename: Borna
authors.initials: B
authors.lastname: Šarić
authors.affiliation: Medical Diagnostics Laboratory, Sveti Duh Clinical Hospital, Zagreb, Croatia.
authors.forename: Monika
authors.initials: M
authors.lastname: Barberić
authors.affiliation: Department of Ophthalmology, Sveti Duh Clinical Hospital, Sveti Duh 64, 10000 Zagreb, Croatia.
authors.forename: Lidija
authors.initials: L
authors.lastname: Andrijašević
authors.affiliation: School of Medicine, University of Zagreb, Croatia.
authors.forename: Branimir
authors.initials: B
authors.lastname: Cerovski
authors.affiliation: Department of Animal Physiology, Faculty of Science, University of Zagreb, Zagreb, Croatia.
authors.forename: Nada
authors.initials: N
authors.lastname: Oršolić
authors.affiliation: Department of Animal Physiology, Faculty of Science, University of Zagreb, Zagreb, Croatia.
authors.forename: Domagoj
authors.initials: D
authors.lastname: Đikić
mesh_terms: D062107:Advanced Oxidation Protein Products / Q000097:blood / Q000378:metabolism; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood / Q000378:metabolism; D001786:Blood Glucose / Q000378:metabolism; D016022:Case-Control Studies; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000378:metabolism; D003930:Diabetic Retinopathy / Q000097:blood* / Q000378:metabolism*; D005260:Female; D005978:Glutathione / Q000097:blood / Q000378:metabolism; D006801:Humans; D008054:Lipid Peroxides / Q000097:blood / Q000378:metabolism; D008297:Male; D008315:Malondialdehyde / Q000097:blood / Q000378:metabolism; D008875:Middle Aged; D018384:Oxidative Stress; D013482:Superoxide Dismutase / Q000097:blood / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A / Q000097:blood / Q000378:metabolism; D014822:Vitreous Body / Q000378:metabolism*
chemical_list: D062107:Advanced Oxidation Protein Products; D015415:Biomarkers; D001786:Blood Glucose; D008054:Lipid Peroxides; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; D008315:Malondialdehyde; D013482:Superoxide Dismutase; D005978:Glutathione