METHODS	Inclusion criteria are : high resolution CT scan with evidence of homogeneous emphysema , post-bronchodilator pulmonary function tests showing : a ratio of FEV1/FVC < 70 % , FEV1 50 % of predicted or FEV1 < 1 liter , RV/TLC 0.65 at screening , marked dyspnea score 2 on the modified Medical Research Council scale of 0-4 , a smoking history of at least 20 pack years and stopped smoking for at least 8 weeks prior to enrollment .\