title: Variability of salivary markers of oxidative stress and antioxidant status in young healthy individuals.
abstract: OBJECTIVE
  Salivary advanced glycation end-products (AGEs), advanced oxidation protein products (AOPP), total antioxidant capacity (TAC), and ferric reducing ability of saliva (FRAS) are increased in various diseases. Little data exist for these markers in the healthy population. The aim of this study was to assess the inter-individual and intra-individual variability of AGEs, AOPP, TAC, and FRAS in the saliva of young healthy individuals.
  
  
  METHODS
  Unstimulated saliva samples were collected from 16 females and 18 males daily over a period of 30 days. Markers were measured using spectrophotometric and spectrofluorometric microplate-based methods.
  
  
  RESULTS
  All salivary markers measured were significantly higher in men than in women (P < 0.05 for AGEs; P < 0.001 for AOPP, TAC, and FRAS). The inter-individual variability was approximately 60% for AGEs and AOPP and 30-40% for TAC and FRAS in both genders. The inter-individual variability of FRAS was higher in men vs. women (P < 0.01). Intra-individual variability ranged from 20% for TAC, to 30% for AGES and FRAS and 45% for AOPP.
  
  
  CONCLUSIONS
  Intra-individual variability of salivary AGEs, AOPP, TAC, and FRAS indicates that their use is currently limited to large cohort studies. Identifying the underlying factors related to the high inter-individual and intra-individual variability is needed. Sex differences should be considered in future studies.
authors.affiliation: a Department of Astronomy, Physics of the Earth and Meteorology, Faculty of Mathematics, Physics and Informatics , Comenius University , Bratislava , Slovakia.|b Department of Nuclear Physics and Biophysics, Faculty of Mathematics, Physics and Informatics , Comenius University , Bratislava , Slovakia.
authors.forename: Ivana
authors.initials: I
authors.lastname: Lettrichová
authors.affiliation: c Institute of Molecular Biomedicine, Faculty of Medicine, Comenius University , Bratislava , Slovakia.|d Center for Molecular Medicine, Slovak Academy of Science , Bratislava , Slovakia.
authors.forename: L'ubomíra
authors.initials: L
authors.lastname: Tóthová
authors.affiliation: c Institute of Molecular Biomedicine, Faculty of Medicine, Comenius University , Bratislava , Slovakia.|d Center for Molecular Medicine, Slovak Academy of Science , Bratislava , Slovakia.|e Faculty of Medicine , Institute of Physiology, Comenius University , Bratislava , Slovakia.
authors.forename: Július
authors.initials: J
authors.lastname: Hodosy
authors.affiliation: c Institute of Molecular Biomedicine, Faculty of Medicine, Comenius University , Bratislava , Slovakia.|f Institute of Physiology, Academy of Sciences of the Czech Republic , Prague , Czech Republic.
authors.forename: Michal
authors.initials: M
authors.lastname: Behuliak
authors.affiliation: c Institute of Molecular Biomedicine, Faculty of Medicine, Comenius University , Bratislava , Slovakia.|d Center for Molecular Medicine, Slovak Academy of Science , Bratislava , Slovakia.|g Institute of Pathophysiology, Faculty of Medicine, Comenius University , Bratislava , Slovakia.|h Department of Molecular Biology, Faculty of Natural Sciences , Comenius University , Bratislava , Slovakia.
authors.forename: Peter
authors.initials: P
authors.lastname: Celec
keywords: Biomarkers of oxidative stress; Carbonyl stress; Sex difference