1. Magnetic Resonance Centre and Department of Chemistry, University of Florence, Via Luigi Sacconi 6, 50019 Sesto Fiorentino, Italy, Magnetic Resonance Centre and Department of Agricultural Biotechnology, P. le delle Cascine 28, 50144 Florence, Italy, and Medical Genetics Unit, IRCCS CSS, Viale Padre Pio, 71013 San Giovanni Rotondo (FG), Italy