[1] Brigham & Womens Hosp, Channing Div Network Med, 75 Francis St, Boston, MA 02115 USA
[2] Harvard Med Sch, Boston, MA 02115 USA
[3] Natl Heart & Lung Inst, Airways Dis Sect, London, England
[4] Natl Heart & Lung Inst, London SW3 6LY, England
[5] Karolinska Inst, SE-17177 Stockholm, Sweden
[6] European Inst Syst Biol & Med, Lyon, France
[7] Southampton Gen Hosp, Southampton S016 6YD, Hants, England
[8] Univ Amsterdam, Acad Med Ctr, NL-1105 AZ Amsterdam, Netherlands