Expiratory Flow Limitation and Its Relation to Dyspnea and Lung Hyperinflation in Patients with Chronic Obstructive Pulmonary Disease: Analysis Using the Forced Expiratory Flow-Volume Curve and Critique

Background: Tidal expiratory flow limitation (tEFL) is defined as absence of increase in air flow during forced expiration compared to tidal breathing and is related to dyspnea at rest and minimal exertion in patients with chronic airflow limitation (CAL). Tidal EFL has not been expressed as a continuous variable (0% - 100%) in previous analyses. Objective: To relate the magnitude of tEFL to spirometric values and Modified Medical Research Council (MMRC) score and Asthma Control Test (ACT). Methods: Tidal EFL was computed as percent of the tidal volume (0% - 100%) spanned (intersected) by the forced expiratory-volume curve. Results: Of 353 patients screened, 192 (114 M, 78 F) patients (136 with COPD, 56 with asthma) had CAL. Overall characteristics: (mean ± SD) age 59 ± 11 years, BMI 28 ± 7, FVC (% pred) 85 ± 20, FEV1 (% pred) 66 ± 21, FEV1/FVC 55% ± 10%, RV (% pred) 147 ± 42. Tidal EFL in patients with tEFL was 53% ± 39%. Using univariate analysis, strongest correlations were between tEFL and FVC and between tEFL and RV in patients with BMI < 30 kg/m2. In patients with nonreversible CAL, tEFL was positively associated with increasing MMRC, negatively with spirometric measurements, and positively with RV/TLC. In asthmatics, ACT scores were higher in patients with mean BMI ≥ 28 kg/m2 (p < 0.00014) and RV/TLC values > 40% (p < 0.03). Conclusions: Dyspnea is strongly associated with tEFL and lung function, particularly in patients with nonreversible CAL. Air trapping and BMI contribute to tEFL.

Montelukast improves air trapping, not airway remodeling, in patients with moderate-to-severe asthma： a pilot study

Background Evidence has demonstrated that the distal lung,which includes airways of 〈2 mm in diameter and lung parenchyma,constitutes an important component of asthma pathology.Cysteinyl leukotrienes （CysLTs） are potent proinflammatory mediators and bronchoconstrictors involved in the asthmatic process.Guidelines recommend the leukotriene-modifying agents for asthma treatment.We hypothesized that a leukotriene receptor antagonist with an inhaled corticosteroid （ICS） and long-acting β2 agonist （LABA） combination would improve small airways function in moderate-tosevere asthmatics evaluated by physiological tests and high-resolution computed tomography （HRCT） analysis.This study was performed at a tertiary university hospital in Beijing.Methods This was a randomized,double-blind,parallel study performed in 38 patients with moderate-to-severe asthma treated with salmeterol/fluticasone （SFC） plus montelukast （SFC＋M） or SFC plus placebo over 24 weeks.Small airway function was assessed by physiological studies and HRCT image analysis.Results Montelukast significantly improved air trapping as expressed by the residual volume （RV）/total lung capacity （TLC）.Over 24 weeks of treatment,RV/TLC was improved by （15.41±6.67）% in patients receiving SFC＋M while RV/TLC was decreased by （8.57±10.26）% in patients receiving SFC alone,the difference between the two groups was significant （P=0.02）.There was a trend towards a significant difference in forced expiratory volume in the first second （FEV1）/forced vital capacity （FVC） in the SFC＋M group compared to that in the SFC group （（17.87±8.17）% vs.（12.28±9.20）%,P=0.056）.There was no significant change in percentage wall area （WA%） after 24 weeks of add-on treatment with montelukast.Patients receiving SFC＋M showed significant improvement in the ratio of CT-determined values at full expiration to those at full inspiration （E/I ratio） （0.894±0.005 vs.0.871±0.003,P=0.002）.Conclusion We have shown,using lung function tests and HRCT image technique,that add-on therapy with montelukast improves distal lung function reflected by air trapping,but not airway wall thickness in moderate-to-severe asthma.（ClinicalTrials.gov number,NCT00699062）

The effect of noise barriers on viaducts on pollutant dispersion in complex street canyons

The noise reduction effect of noise barriers has been extensively studied,but the effect on pollutant dispersion remains unclear.A computational fluid dynamics(CFD)simulation is conducted to investigate the effects of different heights,lengths,and types of noise barriers and different wind speeds on pollutant dispersion in street canyons with viaducts.The field synergy theory of the convective mass transfer process is used for quantitative analysis of pollutant dispersion in street canyons.The results show that as the height and length of the noise barrier increase,the pollutant dispersion capacity decreases.As the wind speed increases,the rate of decrease in the average CO concentration declines.The effect of the wind speed on the synergistic improvement of the speed and concentration gradient vectors differs for different types of noise barriers.The performance follows the order:fully-closed noise barrier>left noise barrier>right noise barrier>semi-closed noise barrier.The different noise barrier types significantly impact the flow field and pollutant dispersion and reduce the CO concentration to varying degrees,except for the fully-closed type.The average CO concentration in the pedestrian breathing zone is reduced by a maximum of 55.85%on the leeward side and by 53%on the windward side,indicating that an appropriate noise barrier on the viaduct reduces noise pollution and improves the air quality in street canyons,especially in the pedestrian breathing zone.

Cell adhesive spectra along surface wettability gradient from superhydrophilicity to superhydrophobicity

Surface wettability is important to design biointerfaces and functional biomaterials in various biological applications. However,to date, it remains some confusions about how cells would response to the surfaces with different wettabilities. Herein,we systematically explore the adhesive spectra of cells to the surface with wettability gradient from superhydrophilicity to superhydrophobicity, clarifying the effect of wettability on cell adhesion. We envision that this study may provide valuable information for the design of biomedical implants with controllable cell adhesion, such as neural interface devices and flexible implant.

Laser textured dimple-patterns to govern the surface wettability of superhydrophobic aluminum plates

A laser texturing technique herein can endow bare aluminum alloy surface with regular dimple-pattern array and thus generates a case hardening.After STA treatment,these laser-textured samples become superhydrophobic.The surface wettability of the laser-textured samples can be regulated by controlling the dimple-pattern dimensions during the laser processing.It is noteworthy that a fluorescence method is utilized to record the zones on the superhydrophobic surface penetrated by small enough water molecules.Compared with a general method of the Cassie-Baxter theoretical calculation,this fluorescence method intuitively exhibits the air trapping ability of the superhydrophobic surface.Furthermore,the laser-textured superhydrophobic samples have a notable hysteresis phenomenon at the initial period of UMT friction because the air cushion trapped within superhydrophobic samples have strong repellency against water droplets on the hydrophilic steel ball.Additionally,such samples display strong mechanical stability in comparison with bare aluminum alloy because of the presence of case hardening on the surface of the laser patterns.The research results above provide a valuable reference for designing a surface with different wettability,which may inspire practical applications in the fields of fluid transport,droplet manipulation,water harvesting and microfluidic devices.