1. Division of Pulmonary and Critical Care Medicine, Department of Medicine, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA
2. Pulmonary Department, General Hospital of Corfu, Los Angeles, CA 90033, Corfu, Greece
3. Department of Pathology, University of Southern California, Los Angeles, CA 90033, USA
4. Department of Biostatistics, Clinical Trials Unit, University of Southern California, Los Angeles, CA 90033, USA