Research Article Plasma Levels of Aminothiols, Nitrite, Nitrate, and Malondialdehyde in Myelodysplastic Syndromes in the Context of Clinical Outcomes and as a Consequence of Iron Overload Kristýna Pimková, 1 Leona Chrastinová, 1 Jilí Suttnar, 1 Jana Štikarová, 1 Roman Kotlín, 1 Jaroslav Hermák, 2 and Jan Evangelista Dyr 1 1 Department of Biochemistry, Institute of Hematology and Blood Transfusion, U Nemocnice 1, 128 00 Prague 2, Czech Republic 2 Clinical Department, Institute of Hematology and Blood Transfusion, U Nemocnice 1, 128 00 Prague 2, Czech Republic Correspondence should be addressed to Krist´ yna Pimkov´ a; kristyna.pimkova@uhkt.cz Received 25 September 2013; Revised 15 November 2013; Accepted 18 December 2013; Published 14 January 2014 Academic Editor: Dimitrios Tsikas Copyright © 2014 Krist´ yna Pimkov´ a et al. his is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. he role of oxidative stress in the initiation and progression of myelodysplastic syndromes (MDS) as a consequence of iron overload remains unclear. In this study we have simultaneously quantiied plasma low-molecular-weight aminothiols, malondialdehyde, nitrite, and nitrate and have studied their correlation with serum iron/ferritin levels, patient treatment (chelation therapy), and clinical outcomes. We found signiicantly elevated plasma levels of total, oxidized, and reduced forms of cysteine ( < 0.001), homocysteine ( < 0.001), and cysteinylglycine ( < 0.006) and signiicantly depressed levels of total and oxidized forms of glutathione ( < 0.03) and nitrite ( < 0.001) in MDS patients compared to healthy donors. Moreover, total ( = 0.032) and oxidized cysteinylglycine ( = 0.029) and nitrite ( = 0.021) difered signiicantly between the analyzed MDS subgroups with diferent clinical classiications. Malondialdehyde levels in plasma correlated moderately with both serum ferritin levels ( = 0.78,  = 0.001) and serum free iron levels ( = 0.60,  = 0.001) and were signiicantly higher in patients with iron overload. he other analyzed compounds lacked correlation with iron overload (represented by serum iron/ferritin levels). For the irst time our results have revealed signiicant diferences in the concentrations of plasma aminothiols in MDS patients, when compared to healthy donors. We found no correlation of these parameters with iron overload and suggest the role of oxidative stress in the development of MDS disease. 1. Introduction Myelodysplastic syndromes (MDS) are a heterogeneous group of clonal hematological disorders, characterized by inefective hematopoiesis and a high risk of transformation into acute myeloid leukemia (AML). Although the origin of MDS development is not fully understood, it has been determined that oxidative stress plays an important role in the initialization and disease progression of MDS [1]. One of the suggested mechanisms causing oxidative stress in MDS is attributed to a non-transferrin-bound iron (NTBI or free iron), which has been found in higher levels in the early stages of MDS patients receiving frequent red blood cell (RBC) transfusions [2]. Several studies have found elevated levels of oxidative stress markers (reactive oxygen species) and reduced levels of antioxidants (reduced glutathione (GSH)) in MDS patients and their correlation with serum ferritin levels [3, 4]. However, increased oxidative stress was revealed, even in the patients not receiving transfusions [5]. he presence of several other oxidative stress markers has been described in patients with established MDS, indepen- dent of iron or ferritin levels [6–8]. Oxidative stress, the imbalance in prooxidative and antioxidative processes, in favour of the irst, acts through reactive oxygen species (ROS) and reactive nitrogen species (RNS). Oxidative status is relected in blood plasma by actors of oxidative stress (free radicals and their metabo- lites), their products such as modiied biomacromolecules, Hindawi Publishing Corporation Oxidative Medicine and Cellular Longevity Volume 2014, Article ID 416028, 10 pages http://dx.doi.org/10.1155/2014/416028