1. The Minnesota CF Center, Department of Medicine, University of Minnesota School of Medicine, Minneapolis, Minnesota, USA
2. Department of Pediatric Otolaryngology, University of Minnesota School of Medicine, Minneapolis, Minnesota, USA
3. Department of Medicine, Hennepin County Medical Center, University of Minnesota School of Medicine, Minneapolis, Minnesota, USA
4. Center for Excellence in Pulmonary Biology, Department of Pediatrics, Stanford University School of Medicine, Palo Alto, California, USA