Enhanced levels of asymmetric dimethylarginine in a serum of middle age patients with myelodysplastic syndrome.

Myelodysplastic syndromes (MDS) are hematological malignancies of unclear etiology where oxidative stress may contribute to the pathogenesis. Methylarginines, naturally occurring inhibitors of NO synthase, can increase superoxide generation from uncoupled NO synthase. We found significant increase in concentrations of asymmetric dimethylarginine (0.84 ± 0.32 μmol/L, p = 0.0022) and malondialdehyde (0.77 ± 0.11 μmol/L, p < 0.001) in sera of MDS patients vs controls (asymmetric dimethylarginine: 0.56 ± 0.16 μmol/L, malondialdehyde: 0.52 ± 0.07 μmol/L). On the contrary, nitrites concentrations were significantly decreased in MDS patients (1.71 ± 0.46 μmol/L, p = 0.0028) vs controls (2.16 ± 0.38 μmol/L). We suppose that the oxidative stress in MDS is enhanced due to methylated arginines influence on NO synthase activity impairment.