American journal of respiratory and critical care medicine
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Am. J. Respir. Crit. Care Med. · May 2001
Comparative StudyIncreased expression of transforming growth factor-beta1 in small airway epithelium from tobacco smokers and patients with chronic obstructive pulmonary disease (COPD).
Tobacco smoke is believed to cause small airway disease and then chronic obstructive pulmonary disease (COPD), but the molecular mechanisms by which small airway obstruction occurs remain unknown. To study the gene expression levels of transforming growth factor (TGF)-beta1, a potent fibrogenic factor, in small airway epithelium from smokers and patients with COPD, we harvested highly pure samples of epithelial cells from small airways under direct vision by using an ultrathin bronchofiberscope BF-2.7T (outer diameter 2.7 mm with a biopsy channel of 0.8 mm in diameter). The expression levels of TGF-beta1 were evaluated by reverse transcription-polymerase chain reaction (RT-PCR). ⋯ Spontaneously released immunoreactive TGF-beta1 levels from cultured epithelial cells were more elevated in subjects with a history of smoking and patients with COPD than in nonsmokers. Our study showed a close link between smoking and expression of TGF-beta1 in small airways. Our results also suggested that small airway epithelial cells might be involved in obstructive changes found in smokers and patients with COPD.
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Am. J. Respir. Crit. Care Med. · May 2001
Alveolar fluid clearance is impaired in the majority of patients with acute lung injury and the acute respiratory distress syndrome.
Because experimental studies have shown that intact alveolar epithelial fluid transport function is critical for resolution of pulmonary edema and acute lung injury, we measured net alveolar fluid clearance in 79 patients with acute lung injury or the acute respiratory distress syndrome. Pulmonary edema fluid and plasma were sampled serially in the first 4 hours after intubation. Net alveolar fluid clearance was calculated from sequential edema fluid protein measurements. ⋯ Endogenous and exogenous catecholamines did not correlate with alveolar fluid clearance. Patients with maximal alveolar fluid clearance had significantly lower mortality and a shorter duration of mechanical ventilation. In summary, in contrast to hydrostatic pulmonary edema, alveolar fluid clearance in patients with acute lung injury and the acute respiratory distress syndrome is impaired in the majority of patients, and maximal alveolar fluid clearance is associated with better clinical outcomes.
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Am. J. Respir. Crit. Care Med. · May 2001
Inspiratory capacity, dynamic hyperinflation, breathlessness, and exercise performance during the 6-minute-walk test in chronic obstructive pulmonary disease.
Patients with severe chronic obstructive pulmonary disease (COPD) develop dynamic lung hyperinflation (DH) during symptom-limited incremental and constant work exercise with cycle ergometer and treadmill. The increase in end-expiratory lung volume seems to be the best predictor of dyspnea. Quantification of DH is based on the relatively complex use of on-line measurement of inspiratory capacity (IC) from flow volume loops. ⋯ Exertional dyspnea correlated with DeltaIC (r = -0.49, p < 0.00001) and baseline MRC (r = 0.59, p < 0.00001). In many patients with COPD, walking leads to DH that can be easily determined with simple spirometric testing. DH helps explain exercise capacity limitation and breathlessness during simple daily activities.