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A simple, reliable, and reproducible fluorometric method for measuring thiobarbituric acid-reactive substances (TBARS) in serum is proposed, based on the reaction between malondialdehyde (MDA) and thiobarbituric acid. Formation of TBARS was complete at pH 2.4-2.6, but extraction with n-butanol proved complete only at lower pH, i.e., 1.6-1.7. Analytical recoveries of MDA added to serum were 94%-101%; within- and between-run CVs were 2.4-3.6% and 4.6-5.5%; and the detection limit for TBARS in serum was 0.10 mumol/L. Optimized conditions included: (a) collection of either serum or heparinized plasma, (b) preservation from in vitro autoxidation by glutathione and EDTA, and (c) storage at -20 degrees C up to 35 days. The mean (+/- SD) TBARS concentration in 47 healthy adults was 1.01 (0.21) mumol/L; no sex-related difference was observed. Higher concentrations were measured in patients with renal insufficiency undergoing hemodialysis and in patients with insulin-dependent diabetes, chronic pancreatitis, or liver cirrhosis.

Oxidative stress represents a situation where there is an imbalance between the reactive oxygen species (ROS) and the availability and the activity of antioxidants. This balance is disturbed by increased generation of free radicals or decreased antioxidant activity. It is very important to develop methods and find appropriate biomarkers that may be used to assess oxidative stress in vivo. It is significant because appropriate measurement of such stress is necessary in identifying its role in lifestyle-related diseases. Previously used markers of oxidative stress, such as thiobarbituric acid reactive substances (TBARS) or malondialdehyde (MDA), are progressively being supplemented by new ones, such as isoprostanes (IsoPs) and their metabolites or allantoin. This paper is focusing on the presentation of new ones, promising markers of oxidative stress (IsoPs, their metabolites and allantoin), taking into account the advantage of those markers over markers used previously. Med Pr 2015;66(3):393-405Key words: isoprostanes, oxidative stress, oxidative stress markers, allantoin, metabolites of isoprostanes StreszczenieStres oksydacyjny jest stanem braku równowagi między działaniem reaktywnych form tlenu (RFT) a działaniem antyoksydantów. Równowaga ta może być zakłócona w wyniku zwiększonego działania wolnych rodników lub spadku aktywności antyoksydacyjnej. Zaburzenia te mogą występować zarówno na poziomie komórkowym, jak i całego organizmu. Ponieważ stres oksydacyjny może być podłożem wielu zespołów chorobowych, niezwykle istotne jest znalezienie odpowiednich markerów, które mogą być wykorzystane do oceny jego poziomu in vivo. Stosowane od wielu lat markery -ocenę stężenia aldehyd dimalonowy (MDA) i substancji reagujących z kwasem tiobarbiturowym (thiobarbituric acid reactive substances -TBARS) -stopniowo uzupełnia się nowymi, takimi jak alantoina czy izoprostany (IzoP) wraz z ich metabolitami (IzoP-M). W niniejszej pracy skupiono się na zaprezentowaniu nowych, obiecujących markerów stresu oksydacyjnego (alantoina, IzoP, IzoP-M), ukazując korzyści wynikające z ich stosowania i prognozując dalsze kierunki badań nad ich zastosowaniem. Med. Pr. 2015;66(3):393-405 Słowa kluczowe: izoprostany, stres oksydacyjny, markery stresu oksydacyjnego, alantoina, metabolity izoprostanów Corresponding author / Autorka do korespondencji: Marta Czerska,

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The findings of the present study provide evidence for the hypothesis based on in vitro studies which assumes that GPx1 Pro198Leu polymorphism has a functional significance for the human organism and that this functionality is associated with a different response of GPx1 activity to Se. They also point to the importance of the genetic background in the assessment of the Se status with the use of selenoprotein biomarkers such as GPx1 activity.