rdance to manufacturer's specification. OxLDL values were measured in the enrolled subjects and in 45 healthy subjects, who were matched for age, gender and BMI with the group of patients. The ratio of ox-LDL/LDL-C was calculated. High-sensitivity C-reactive protein (hsCRP), monocyte chemoattractant protein-1 (MCP-1) and tumor necrosis factor-a (TNF-a) serum concentrations were also measured using ELISA, Immundiagnostik AG., Bensheim, Germany, Alpco Diagnostics, Anachem, Salem, NH, USA and Ani Biotech Oy, Orgenium, Helsinki, Finland, respectively, according to the specifications of the manufacturers. The concentrations of intact-parathormone (i-PTH) and insulin were measured by radioimmunoassays (CIS bio international, Saclay, France and BioSource Europe SA, Nivelles, Belgium, respectively). Insulin resistance was calculated using the homeostasis model assessment of insulin resistance (HOMA-IR) \[[@B11-jcdd-05-00035]\].

Normalized protein catabolic rate for dry body mass (nPCR) was calculated from the urea generation rate \[[@B12-jcdd-05-00035]\]. Body mass index (BMI) was obtained from height and post-dialysis body weight.

2.4. Hemodynamic and Echo-Cardiographical Measurements {#sec2dot4-jcdd-05-00035}
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The mean of 12 measurements of pre-dialysis peripheral systolic and diastolic blood pressures (SBP and DBP respectively) was recorded during a treatment month using an automatic sphygmomanometer OMRON M4-I (Co Ltd. Kyoto, Japan). Mean peripheral pre-dialysis BP (MBP) was calculated as: MBP = DBP + 1/3 (SBP − DBP).

Hemodynamic and echo-cardiographical measurements were also performed before the mid-week dialysis session in combination with blood tests after resting of the patients for at least 10 min. Arterial stiffness was measured as carotid-femoral pulse wave velocity (c-f PWV) and carotid augmentation index (Aix) using the SphygmoCor system^®^ (AtCor Medical Pty. Ltd., Sydney, Australia) according to manufacturer's specifications. In each subject, tw