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,

Summary What is known and background:  Although paracetamol (acetaminophen), N‐(4‐Hydroxyphenyl)acetamide, is one of the world’s most widely used analgesics, the mechanism by which it produces its analgesic effect is largely unknown. This lack is relevant because: (i) optimal pain treatment matches the analgesic mechanism to the (patho)physiology of the pain and (ii) modern drug discovery relies on an appropriate screening assay. Objective:  To review the clinical profile and preclinical studies of paracetamol as means of gaining insight into its mechanism of analgesic action. Methods:  A literature search was conducted of clinical and preclinical literature and the information obtained was organized and reviewed from the perspective of its contribution to an understanding of the mechanism of analgesic action of paracetamol. Results:  Paracetamol’s broad spectrum of analgesic and other pharmacological actions is presented, along with its multiple postulated mechanism(s) of action. No one mechanism has been definitively shown to account for its analgesic activity. What is new and conclusion:  Further research is needed to uncover the mechanism of analgesic action of paracetamol. The lack of this knowledge affects optimal clinical use and impedes drug discovery efforts.

Both 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) as well as peroxisome proliferator-activated receptor (PPAR)alpha activators (fibrates) proved to be effective in the primary and secondary prevention of cardiovascular diseases. The benefits of hypolipemic therapy in cardiovascular diseases cannot be explained only by the lipid-lowering potential of these agents. The aim of this study was to clarify the effect of hypolipemic agents on proinflammatory cytokine release from human monocytes in relationship with their action on plasma levels of sensitive systemic marker of low-grade vascular inflammation. Plasma lipid and high-sensitivity C-reactive protein (hsCRP) levels, and the release of tumor necrosis factor-alpha (TNFalpha) and interleukin-1beta from monocytes were assessed at baseline and 30 and 90 days following randomization of IIa dyslipidemic patients into fluvastatin or simvastatin groups and randomization of type IIb dyslipidemic patients to the micronized form of either ciprofibrate or fenofibrate. Lipopolysaccharide-stimulated monocytes from dyslipidemic patients released significantly more TNFalpha (types IIa and IIb dyslipidemias) and interleukin-1beta (type IIa dyslipidemia) in comparison with monocytes in 59 age-, sex-, and weight-matched control subjects. Their baseline hsCRP levels were also higher. Both statins and fibrates reduced the release of TNFalpha and interleukin-1beta, and lowered plasma hsCRP levels. The effects of hypolipemic agents on cytokine release and plasma hsCRP were unrelated to their lipid-lowering action. Our results have demonstrated that type IIa and IIb dyslipidemic patients exhibit the abnormal pattern of TNFalpha and interleukin-1beta production by activated monocytes. Both HMG-CoA reductase inhibitors and PPARalpha activators normalize monocytic secretion of these cytokines, and this action may partially contribute to the systemic antiinflammatory effect of hypolipemic agents. The statin- and fibrate-induced suppression of proinflammatory cytokine release from monocytes seems to play a role in their beneficial effect on the incidence of cardiovascular events.

Isoprostanes are a recently discovered group of prostaglandin isomers. Results of previous studies suggest that they can be used as oxidative stress markers, because in a number of cardiovascular, pulmonary and neurological diseases their levels in biological samples considerably increase. It has been found that people suffering from diabetes, obesity, homozygous familial hypercholesterolemia, moderate hypercholesterolemia, and smokers have higher levels of isoprostanes in urine. The same refers to patients with asthma, Alzheimer disease and Down syndrome. This paper reviews the results of relevant studies.

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