ABSTRACT
Objective Based on computational fluid dynamics (CFD) method, the air and aerosol transport in a single alveolus were simulated to study the characteristics of airflow and aerosol transport in deep alveolus. Methods A long straight duct with a hemispherical wall at one end which had periodic expansion/contraction were regarded as simplified approximation of a single alveolus. Based on this, a two-dimensional (2D) mathematical model was established.The Euler-Euler method was used to solve the transport equations of airflow and aerosol particles in the alveolus considering air diffusion along the hemisphere boundary. Results The composition ratio of the air in the duct changed in a stable periodic way during the whole breathing process.The aerosol transport in the duct mainly depended on the particle diffusion coefficient. The advection transport had only a small effect on it. The diffusion velocity and depth of aerosol increased when the particle size decreased, especially when the particle size was smaller than 4 μm. The increase of respiratory frequency and amplitude could significantly improved the transport capacity of aerosol particles. Conclusions In atomization treatment, aerosol particles with smaller particle size have better transportation and curative efficacy. Deep breathing should be encouraged to improve particle transport.
ABSTRACT
Objective To investigate the protective effect of modified Qianjin Weijing Decoction(MQJWJD)on TNF-α and NF-κB in rats with lung injury induced by particulate matter; To discuss relevant mechanism of action. Methods A tracheal drip 15 mg/kg fine particles of saline solution was used to establish modeling, every other day, three times. Thirty-two Wistar rats were randomly divided into normal group, model group and MQJWJD high-dose and low-dose groups, with eight rats in each group. Medication groups were given relevant medicine for gavage. The level of TNF-α in bronchoalveolar lavage fluid (BALF) was measured by ELISA. The expression of NF-κB protein in lung tissues was measured by immunohistochemistry. The histopathology of the lung injury was observed by light microscope. Results Compared with normal group, the level of TNF-α and the expression of NF-κB protein in the model group were higher than those in the normal group (P<0.01). Compared with model group, the level of TNF-α and the expression of NF-κB protein in MQJWJD low-dose and high-dose groups were lower than those in the model group (P<0.05, P<0.01). Pathological observation showed that, compared with normal group, model group showed intratracheal, alveolar and interstitial bacteria within a large number of fine particles calm, alveolar and pulmonary interstitial visible large amounts of phagocytic fine particles of macrophages and accompanied by more neutrophils and lymphocyte infiltration; Lung tissue pathological changes were significantly lighter in MQJWJD high-dose and low-dose groups than the model group. MQJWJD high-dose group showed mild inflammation, alveolar and pulmonary interstitial visible phagocytic fine particles of macrophages, a small amount of neutrophils and lymphocyte infiltration. Conclusion MQJWJD can reduce the pulmonary injury in rats induced by particulate matter and has protective effects on the rat model through decreasing the levels of TNF-α and the expressions of NF-κB protein in injured lung tissues.