ABSTRACT
In striated muscle, chronic increases in workload result in changes in myosin phenotype. The aim of this study was to determine whether such changes occur in the diaphragm of patients with severe chronic obstructive pulmonary disease, a situation characterized by a chronic increase in respiratory load and lung volume. Diaphragm biopsies were obtained from 22 patients who underwent thoracic surgery. Myosin was characterized with electrophoresis in nondenaturing conditions, SDS-glycerol PAGE, and Western blotting with monoclonal antibodies specific for slow and fast myosin heavy chain (MHC) isoforms. Flow volume curves, total lung capacity, and functional residual capacity were measured before surgery in 20 patients. We found that the human diaphragm is composed of at least four myosin isoforms, one slow and three fast, resulting from the combination of three MHC species. Chronic overload was associated with an increase in the slow beta-MHC species at the expense of the fast species (beta-MHC, 78.2 +/- 4.6 and 50.0 +/- 6.5% in emphysematous and control patients, respectively; P < 0.005). Linear correlations were found between beta-MHC percentage and forced expiratory volume in 1 s (r = -0.52; P < 0.02), total lung capacity (r = 0.44; P < 0.05), and functional residual capacity (r = 0.65; P < 0.003). The human adult diaphragm is composed of a balanced proportion of slow and fast myosin isoforms. In patients with chronic obstructive pulmonary disease, the proportion of fast myosins decreases, whereas that of slow myosin increases. This increase appears to be closely related to lung hyperinflation and may reflect an adaptation of the diaphragm to the new functional requirements.
Subject(s)
Diaphragm/physiopathology , Gene Expression , Lung Diseases/genetics , Lung Diseases/physiopathology , Myosin Heavy Chains/genetics , Adult , Aged , Blotting, Western , Chronic Disease , Diaphragm/metabolism , Electrophoresis, Polyacrylamide Gel , Female , Humans , Lung Diseases/metabolism , Lung Diseases, Obstructive/metabolism , Male , Middle Aged , Myosin Heavy Chains/metabolism , Respiration/physiologyABSTRACT
The fibroscopic examination of 180 patients treated for small cell lung carcinoma is studied. The fibroscopy permits a good diagnosis in at least 93.3% of cases. In the case of failure a mediastinoscopy or transparietal cytopuncture are indicated. The absence of a correlation between a radiological remission and endoscopic remission justifies an endoscopic control prior to each therapeutic step. After treatment, the endoscopy permits the evaluation of chemotherapeutic and mainly radiotherapeutic bronchial sequellae. Two out of 70 patients treated by both chemotherapy and radiotherapy presented normal bronchial endoscopy.
