Comparison of different levels of positive expiratory pressure on chest wall volumes in healthy children and patients with fibrosis

ABSTRACT Positive Expiratory Pressure (PEP) improves lung function, however, PEP-induced changes are not fully established. The aim of this study was to assess the acute effects of different PEP levels on chest wall volumes and the breathing pattern in children with Cystic Fibrosis (CF). Anthropometric data, lung function values, and respiratory muscle strength were collected. Chest wall volumes were assessed by Optoelectronic plethysmography at rest and during the use of different PEP levels (10 and 20 cm H2O), randomly chosen. Eight subjects with CF (5M, 11.5±3.2 years, 32±9.5 kilograms) and seven control subjects (4M, 10.7±1.5 years, 38.2±7.8 kilograms) were recruited. The CF group showed significantly lower FEF values 25-75% (CF: 1.8±0.8 vs. CG: 2.3±0.6) and FEV1/FVC ratio (CF: 0.8±0.1 vs. CG: 1±0.1) compared with the control group (p<0.05). Different PEP levels increased the usual volume in chest wall and its compartments in both groups; however, this volume was significantly higher in the control group compared with the CF group during PEP20 (CW: 0.77±0.25 L vs. 0.44±0.16 L; RCp: 0.3±0.13 L vs. 0.18±0.1 L; RCa: 0.21±0.1 L vs. 0.12±0.1 L; AB: 0.25±0.1 L vs. 0.15±0.1 L; p<0.05 for all variables). Minute ventilation was significantly higher during PEP compared with breathing at rest in both groups (p<0.005). End-expiratory volume was also higher during PEP compared with breathing at rest for chest wall and pulmonary rib cage in both groups (p<0.05). Different PEP levels may increase chest wall volumes in CF patients

Protein-ligand binding affinity determination by the waterLOGSY method: An optimised approach considering ligand rebinding

WaterLOGSY is a popular ligand-observed NMR technique to screen for protein-ligand interactions, yet when applied to measure dissociation constants (KD) through ligand titration, the results were found to be strongly dependent on sample conditions. Herein, we show that accurate KDs can be obtained by waterLOGSY with optimised experimental setup