Ischemia-modified albumin and advanced oxidation protein products as potential biomarkers of protein oxidation in Alzheimer's disease.

The aim of the present study was to determine the systemic levels of oxidative stress markers, such as ischemia-modified albumin (IMA), advanced oxidation protein products (AOPP), ferric reducing antioxidant power (FRAP) and the prooxidant-antioxidant balance (PAB), to clarify protein redox homeostasis in patients with Alzheimer's disease, and to compare them with mentally healthy persons of the same age. A total of 38 patients with Alzheimer's disease (AD) and 34 sex- and age-matched mentally healthy control subjects were included in this study. The patients had significantly higher AOPP, IMA and PAB in the patient group than in the control group (P = 0.004, P = 0.001, P = 0.007, respectively). The FRAP was significantly lower in the patients with AD than in the control subjects (P = 0.002), and according to the receiver operating characteristic curves, the IMA and AOPP areas are below the 0.700 receiver operating characteristic curve line (area under the curve 0.817 and 0.730, respectively; 95% CI 0.709-0.898 and 0.612-0.828, respectively). Increased IMA, AOPP and PAB, and decreased FRAP are likely to be results of oxidative stress, a condition in which an imbalance occurs between the production and inactivation of reactive oxygen species in AD. The IMA could be used for the better evaluation of clinical status, as well as the independent characteristic symptoms of AD, for the purposes of routine clinical laboratory analysis.