摘要:

ABSTRACTDeposition pattern and efficiency of inhaled particles in bifurcating airways were studied experimentally by using Y-shaped single bifurcation tube models in conjunction with varying branching angles (θ = 15-90°), branching symmetry, and flow distribution pattern between two daughter branches. Monodispersed oil droplets (3, 5 and 7 μm dia.) tagged with uranine were used as test aerosols and sampling flow rate was maintained in the Reynolds number (Re) of 1132-3397. The model tubes were washed section by section with deionized water and the fluorescence content in the washed solution was used for determining deposition efficiency. Particle deposition occurred mainly near the bifurcation and increased with increasing Stokes number (StK). Deposition efficiency did not change with branching angle for θ = 15-45° but increased somewhat for the extreme branching angles of 60° and 90°. Branching asymmetry and flow distribution pattern did not affect the deposition efficiency within the range tested. From these results, a unified formula for deposition efficiency was derived as a single function of Stokes number and compared with theoretical predictions and previous experimental r

ISSN:0894-2684    

DOI:10.1089/jam.1989.2.1

年代:1989

数据来源: MAL

摘要:

ABSTRACTDeposition efficiency of aerosol particles in the bifurcating airways during expiratory phase was investigated by using single bifurcation tube models with different branching angles (θ=15, 30 and 45°) for both symmetric and asymmetric branching geometry. Monodisperse oleic acid droplets (3, 5, and 7 μm dia) tagged with uranine were used as test aerosols, and flow regimes were maintained in Reynolds number of 566-5945. Deposition pattern within the branching tube model was also determined by eluting uranine tracer from different sections of the model. Particle deposition occurred principally in a short section of the parent tube immediately proximal to the bifurcation and increased with increasing flow rate, particle size, or branching angle. Deposition efficiency was uniquely correlatedwithStokes number (Stk) and monotonically increased with a single parameter, √Stk.sinθ. These results and the mechanism of expiratory deposition in the branching airways were discussed in conjunction with previous results for inspiratory flow and theoretical predic

ISSN:0894-2684    

DOI:10.1089/jam.1989.2.15

年代:1989

数据来源: MAL

摘要:

ABSTRACTThe mechanism by which particles deposited in the alveolar region of the lung are translocated to tracheobronchial lymph nodes (TBLN) remains unclear. In the present study, we investigated the ability of rat pulmonary alveolar macrophages (PAM) to contribute to this process. Rats were instilled intratracheally with 5 x 109fluorescent microspheres about 1.3 μm diameter and groups were killed at 1, 2, 4 and 8 days after instillation. Two-micron plastic sections of the TBLN revealed that approximately 90% of the microspheres in the TBLN were within macrophages at each time point. The distribution of the numbers of microspheres per TBLN macrophage did not change between 1 and 8 days even though the total number of particles in the TBLN increased linearly during this time. Had the microspheres accumulated in the TBLN as free particles, it seems likely that there would have been a shift toward larger numbers of microspheres per macrophage with time. We also instilled pulmonary alveolar macrophages (PAM), approximately half of which were labeled with red fluorescent microspheres and half with green fluorescent microspheres, into rat lungs. After three days the TBLN of the rats contained numerous macrophages containing only one color of microsphere. The use of the two colors of microspheres precluded the possibility that the microspheres were translocated as free particles and were phagocytized in the TBLN by resident macrophages. These results suggest that in the rats, a considerable number of microspheres was translocated from lung to TBLN within PAM

ISSN:0894-2684    

DOI:10.1089/jam.1989.2.29

年代:1989

数据来源: MAL

摘要:

ABSTRACTBovine and rat alveolar macrophages were obtained by post-mortem bronchoalveolar lavage. The standard test quartz DQ12 or another quartz type (Sicron F600) were used either in native form in serum-free medium or after treatment with Dipalmitoyl-lecithin (DPL). The dose-effect relationships were analyzed. The results for bovine and rat alveolar macrophages were similar. DPL treatment completely abrogated the cytotoxic effects of quartz, which were monitored by testing the viability of adherent cells and enzyme released into the culture medium. Results obtained by carrier-free electrophoresis indicate that bovine alveolar macrophages are composed of several subpopulations. After incubation with native, but not with DPL-treated quartz particles the electrophoretic pattern was markedly changed.

ISSN:0894-2684    

DOI:10.1089/jam.1989.2.39

年代:1989

数据来源: MAL

摘要:

ABSTRACTA predictive aerosol deposition model, which has been validated by comparison with experimental data from adult test subjects, is used to study particle deposition patterns within the developing human lung. Here, an age-dependent lung morphology is presented in which the growth of bronchial airway dimensions is described by the measurements of Phalen et al. (1985), and the number and sizes of pulmonary airways are derived from Dunnill (1962). Total, and compartmental tracheobronchial and pulmonary deposition fractions are calculated for different breathing patterns, from sedentary to maximal activity, and particle sizes ranging over three orders of magnitude. The influences of human subject age and physical activity levels upon regional aerosol deposition within the developing lung are complex; systematic patterns, however, can be identified which are consistent with the effects of linear airway dimensions and particle flow characteristics upon effective particle deposition mechanisms.

ISSN:0894-2684    

DOI:10.1089/jam.1989.2.49

年代:1989

数据来源: MAL

摘要:

ABSTRACTThe lung deposition of inhaled spherical and fibrous particles in the alveolar ducts has been evaluated. The computations herewith presented are based on four assumed deposition mechanisms: impaction, interception, diffusion and sedimentation. Humans, rats, hamsters, guinea pigs and dogs are among the study subjects. Different deposition patterns were obtained. For rats and hamsters, there was an enhanced deposition at the bifurcation of the alveolar duct. This is in agreement with experimental observations. In contrast, for humans, guinea pigs and dogs, the deposition distribution in the alveolar duct was almost uniform. The difference in deposition pattern among different species may account, in part, for the observed differences in the clearance rate of deposited particles from the alveolar region of the lungs.

ISSN:0894-2684    

DOI:10.1089/jam.1989.2.69

年代:1989

数据来源: MAL

ISSN:0894-2684    

DOI:10.1089/jam.1989.2.76

年代:1989

数据来源: MAL