[1] Univ Ioannina, Sch Med, Dept Internal Med, GR-45110 Ioannina, Greece
[2] Royal Free London Fdn Trust, Dept Clin Biochem, Vasc Dis Prevent Clin, London, England
[3] Med Univ Lodz, Chair Nephrol & Hypertens, Dept Hypertens, Lodz, Poland
[4] UCL, Dept Clin Biochem, Vasc Dis Prevent Clin, Sch Med, London NW3 2QG, England