C Ioannou performed the experiments, contributed to data collection, performed statistic analyses and co-wrote the manuscript. G Ragia designed and developed the protocols, contributed to the interpretation of the results, performed statistic analyses and co-wrote the manuscript. I Balgkouranidou contributed to data collection and aided in interpreting the results. N Xenidis, K Amarantidis, T Koukaki and E Biziota contributed to sample collection and were responsible for data acquisition and patient treatment. S Kakolyris was responsible for patient treatment, supervised the data acquisition and collection. VG Manolopoulos conceived the present idea, supervised the project, revised and edited the final draft.