The main cellular source of reactive oxygen species (ROS) is mitochondrial respiratory chain and active NADPH responsible for "respiratory burst" of phagocytes. Whatsmore ROS are produced in endoplasmic reticulum, peroxisomes, with the participation of xanthine and endothelial oxidase and during autoxidation process of small molecules. Mitochondrial respiratory chain is the main cellular source of ROS. It is considered that in aerobic organisms ROS are mainly formed during normal oxygen metabolism, as byproducts of oxidative phosphorylation, during the synthesis of ATP. The intermembranous phagocyte enzyme - activated NADPH oxidase, responsible for the "respiratory burst" of phagocytes, which is another source of ROS, plays an important role in defense of organism against infections. The aim of this article is to resume actuall knowledge about structure and function of the mitochondrial electron transport chain in which ROS are the byproducts and about NADPH oxidase as well as the function of each of its components in the "respiratory burst" of phagocytes.

In autoimmune inflammatory diseases, including juvenile idiopathic arthritis (JIA), which leads to joint destruction, there is an imbalance between production of reactive oxygen species (ROS) and their neutralization which, as a consequence, leads to “oxidative stress.” The aim of the study was to assess the concentration of oxidative stress markers: nitric oxide (NO), a degree of lipid membrane damage, and total antioxidant plasma capacity in children with JIA. Thirty-four children with JIA were included into the study. A degree of lipid membrane damage (lipid peroxidation products) was estimated as thiobarbituric acid-reactive substances (TBARs), NO concentration as NO end-products: nitrite/nitrate (NO2−/NO3−) and total antioxidant plasma capacity as ferric reducing ability of plasma (FRAP). NO2−/NO3− serum concentration in children with JIA was statistically significantly higher than that in healthy children (p = 0.00069). There was no significant difference in TBAR levels between children with JIA and the control group. FRAP in sera of children with JIA was lower than that in healthy children, but the difference was not statistically significant. A statistically significant positive correlation was observed between NO end products and the 27-joint juvenile arthritis disease activity score (JADAS-27) and ESR, and a negative correlation was observed between FRAP and C-reactive protein (CRP) and white blood cell count (WBC). Our results confirm the increased oxidative stress in children with JIA. Overproduction of NO and decrease in the antioxidant plasma capacity may be involved in JIA pathogenesis.

The goal of the study was to evaluate the diagnostic and prognostic value of anti-mutated citrullinated vimentin (anti-MCV) antibodies in juvenile idiopathic arthritis (JIA) comparing to anti-cyclic citrullinated peptide (anti-CCP). Thirty children with confirmed JIA diagnosis and 20 children as a control group were included into the study. Serum and synovial fluid levels of anti-CCP, anti-MCV, and immunoglobulin M rheumatoid factor (IgM-RF) antibodies have been assessed. Anti-MCV was positive in 11/30 (36.6 %), whereas anti-CCP positivity was found in 12/30 (40 %) children with JIA. Among 11 children with JIA positive for anti-MCV, five (45.5 %) were also positive for anti-CCP and among 18 JIA children negative for anti-CCP, six (33.33 %) were also anti-MCV positive. Six out of 30 JIA children were found to be IgM-RF positive. In general, two out of all those 11 anti-MCV-positive patients demonstrated oligoarthritis and 9/11 had polyarticular type of onset. Anti-MCV serum concentration correlated positively with anti-CCP (p = 0.004). Almost 60 % of children in early stage of JIA were anti-MCV positive. Levels of anti-CCP antibodies correlated positively with the disease activity (p = 0.0014) and radiological outcome (p = 0.00017). In all synovial fluid samples, the concentration of autoantibodies was under the cut-off values. The results of our study indicate that anti-MCV as well as anti-CCP antibodies may be helpful in the diagnosis of JIA, especially in the early course of the disease. Anti-MCV antibodies could identify a group of children with JIA which is negative for anti-CCP antibodies and RF. However, it appears that in JIA, anti-CCP rather than anti-MCV antibodies have impact on radiographic changes.

We investigated if IRFI 042, an analog of vitamin E, protects the brain against oxidative stress induced by intraperitoneal administration of Kainic acid (KA) (10 mg/kg); sham brain injury rats were used as controls. Animals received either IRFI 042 (20 mg/kg) or its vehicle 30 min before KA injection and after 6 h were sacrificed to measure malonildyaldheide (MDA) and glutathione levels (GSH) in the diencephalon. Behavioral changes were also monitored. Intraperitoneal administration of IRFI decreased MDA (micromol/g wet tissue: KA + vehicle ¼ 22.5 ± 4.2; KA + IRFI ¼ 17.1 ± 1; P < 0.005) and prevented GSH loss (nmol/g wet tissue: KA + vehicle ¼ 0.41 ± 0.1; KA + IRFI ¼ 1.86 ± 0.2; P < 0.005) in the diencephalon. The latency of occurrence of behavioral signs increased from 39 ± 1 to 62 ± 6 min in IRFI 042 group. The data suggest that IRFI 042 might protect against KA-induced oxidative stress. PS6-02Reactive oxygen species production in synaptosomes is independent of DW m I. Sipos, L. Tretter and V. Adam-Vizi Department of Medical Biochemistry, Semmelweis University, Budapest, Hungary, sipos@puskin.sote.hu This study addressed whether dissipation of DW m had any influence on ROS generation of in situ neuronal mitochondria. The ROS formation was measured as a release of H 2 O 2 by Amplex Red assay. Complete blockage of Complex I by rotenone or Complex III by antimycin caused enhanced H 2 O 2 release. Dissipation of DW m by FCCP or DNP had no effect on the H 2 O 2 production induced by rotenone or antimycin. Antimycin substantially diminishes the DW m , but part of the membrane potential still maintained by the reverse function of mitochondrial ATP synthase. When antimycin was applied together with oligomycin, DW m was totally dissipated, but the ROS production decreased only by 15%. Rotenone inhibited the antimycin-induced H 2 O 2 release by 55%, but not eliminated completely. These experiments suggest that in in situ mitochondria of synaptosomes (i) ROS generation because of inhibition of Complex I or III is not dependent on DW m and (ii) when Complex I is completely inhibited electrons entering the respiratory chain distal from rotenone site could fuel the ROS formation. PS6-03Free radical production in synaptosomes: the effect of respiratory substrates L. Tretter, I. Sipos, M. Miklos and V. Adam-Vizi Department of Medical Biochemistry, Semmelweis University, Budapest, Hungary, tretter@puskin.sote.huWe investigated whether reactive oxygen species (ROS) production is different when the metabolism is driven by alternative respiratory substrates (RES) in synaptosomes. ROS production was monitored with the Amplex Red assay and parallel with that aconitase activity was measured, as this enzyme is sensitive to inhibition by ROS. Inactivation of aconitase and ROS production in synaptosomes run parallel when ROS production is induced by inhibition of respiratory complexes. In the presence of either isocitrate, alphaketoglutarate (a-KG), succinate or pyruvate but not citrate ROS production was enhanced as indicated by the ...

Abstract.We investigated the effect of long-term oral melatonin administration on the antioxidant capacity of plasma. The study was performed on healthy volunteers divided into two groups: the control group (without melatonin treatment) and the study group treated with 6 mg of melatonin per day for two weeks, 2 hours before bedtime. Blood samples were drawn: before melatonin administration, on the 7 th and 14 th day of melatonin treatment and on the 10 th day after the last dose of melatonin. It was shown that oral administration of melatonin increases plasma antioxidant ferric reducing ability (FRAP assay) (p < 0.05) and DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging (p < 0.01), and decreases thiobarbituric acid reactive substances (TBARS) (p < 0.05) and DNA damage (p < 0.001). This protective effect is maintained for at last 10 days after discontinuation of the treatment.The present work highlights that the antioxidant capacity of plasma was significantly higher on the 10 th day after the discontinuation of melatonin treatment than on the 14 th day of its administration. Our findings indicated that a long-term oral melatonin administration maintained the increased antioxidant capacity of plasma and prevented oxidative damage to DNA after hormone administration was discontinued.