1. Pulmonary Rehabilitation Unit, ICS Maugeri SpA IRCCS, Via Bagni Vecchi 1, 82037 Telese Terme (Benevento), Italy
2. Institute of Biomolecular Chemistry, National Research Council, Via Campi Flegrei 34, Comprensorio Olivetti Edificio A, 80078 Pozzuoli (Naples), Italy
3. Department of Respiratory Medicine, University Federico II, 80131 Naples, Italy