Oxidative stress in thalassemia is caused by secondary iron overload and stems from blood transfusion and increased iron uptake. In this study, we hypothesized that levels of o- and m-tyrosine, products of hydroxyl radical attack on phenylalanine, would be elevated in beta-thalassemia (intermediate). This study represents the first report in which specific markers of protein oxidative damage have been quantified in thalassemia. We used GC/MS to assay o- and m-tyrosine at the femtomole level using only a few microliters of plasma. Levels of both markers were significantly higher in patients with beta-thalassemia than in controls and were positively correlated with serum ferritin, malondialdehyde, superoxide dismutase, glutathione peroxidase and glutathione. We conclude that o- and m-tyrosine are useful biomarkers of oxidative damage to proteins in thalassemia (intermediate) and may also be useful markers in other iron overload diseases. Positive correlations between o- and m-tyrosine levels and malondialdehyde as well as antioxidants such as superoxide dismutase, glutathione peroxidase and glutathione, are indicative of the broad impact of oxidative stress on blood plasma in thalassemia, with up-regulation of antioxidant proteins probably reflecting a homeostatic response to these increased stress levels.

中文翻译：

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定量测定邻位和间位酪氨酸作为β地中海贫血中蛋白质氧化损伤的生物标志物。

地中海贫血中的氧化应激是由继发性铁超载引起的，源于输血和铁吸收增加。在这项研究中，我们假设β-地中海贫血（中度）会升高羟基自由基攻击苯丙氨酸的产物邻-和间-酪氨酸的水平。这项研究代表了第一个报告，其中在地中海贫血中定量了蛋白质氧化损伤的特定标记。我们仅使用几微升血浆就使用了GC / MS在飞fe水平上测定邻酪氨酸和间酪氨酸。β-地中海贫血患者的两种标记物水平均显着高于对照组，并且与血清铁蛋白，丙二醛，超氧化物歧化酶，谷胱甘肽过氧化物酶和谷胱甘肽呈正相关。我们得出结论，邻-和间-酪氨酸是地中海贫血（中度）中蛋白质氧化损伤的有用生物标志物，也可能是其他铁超负荷疾病的有用标志物。邻酪氨酸和间酪氨酸水平与丙二醛以及抗氧化剂（如超氧化物歧化酶，谷胱甘肽过氧化物酶和谷胱甘肽）之间呈正相关关系，表明地中海贫血中氧化应激对血浆的广泛影响，抗氧化剂蛋白的上调可能反映了对这些增加的压力水平的稳态反应。