2007 Progress Report: Project 5 -- Architecture Development and Particle DepositionEPA Grant Number: R832414C005
Subproject: this is subproject number 005 , established and managed by the Center Director under grant R832414
(EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
Center: San Joaquin Valley Aerosol Health Effects Research Center (SAHERC)
Center Director: Wexler, Anthony S.
Title: Project 5 -- Architecture Development and Particle Deposition
Investigators: Wexler, Anthony S. , Plopper, Charles
Institution: University of Delaware , University of California - Davis
Current Institution: University of California - Davis
EPA Project Officer: Chung, Serena
Project Period: October 1, 2005 through September 30, 2010 (Extended to September 30, 2011)
Project Period Covered by this Report: October 1, 2006 through September 30, 2007
RFA: Particulate Matter Research Centers (2004) RFA Text | Recipients Lists
Research Category: Human Health , Air
Quantify lung architecture changes due to pollutant exposure during development.
Two current activities are highlighted below, first, acquisition of CT image data for seven normal rats, and second, characteristics of pulmonary architecture.
1. Acquisition of CT image data for seven rats
The lung casts from seven male Sprague Dawley rats were imaged using a commercially available micro CT scanner, MicroCAT II (Siemens, Knoxville, TN) in high resolution mode with a 0.5 mm aluminum filter. To prevent motion artifacts, the cast was imaged in a plastic tray. Three hundred sixty projections were acquired during a full rotation of the micro CT scanner around the cast with the following scan parameters: 80 kVp, 500 μA, 1250 ms per frame and 30 calibration images (bright and dark fields). The image was reconstructed using the Feldkamp reconstruction algorithm as a 768 x 768 x 1000 array with corresponding voxel size of 0.053 mm x 0.053 mm x 0.053mm. Higher resolution data (pixel size is 0.026 mm) from a single rat was also analyzed to confirm that the resolution mode used is fine enough to distinguish the smallest airways. A sample of iso-surface reconstruction of airways is shown below in Figure 1.
Figure 1. Iso-surface reconstruction of CT image
2. Characteristics of pulmonary architecture
We analyzed the airway architecture of seven normal rats using an algorithm tp model airway architecture that we developed previously (publication submitted). The modeling algorithm was validated by error analysis and a statistical comparison of our airway model results with measurements from previous studies of rat lung anatomy (Raabe 1976; Phillips 1995). The statistical results from our modeling study and Raabe’s measurements were very similar (Figure 2) except that the small airways (diameter smaller than 1mm) in our analysis were much more symmetric than Raabe’s (Figure 3). Most notably the current study showed that the mean value and standard deviation of the geometric parameters are insufficient to characterize airway architecture in the lung. For example, we found that the twist angle, i.e., the angle between successive bifurcations, is far from normally distributed (Figure 4). Thus, the typical distribution of the values of airway geometry must be taken into account to quantitatively describe pulmonary architecture. Using SAS we are performing statistical analysis including intersubject variance.
Figure 2. Airway diameter vs Generation
Figure 3. Asymmetry vs Diameter
Figure 4. Distribution of twist angle
We will analyze rat lungs exposed to ozone and/or particles, and compare them to normal lungs. Ozone exposures are currently underway.
Raabe, O.G., Yeh, H.C., Schum, G.M., Phalen, R.F. Tracheobronchial Geometry: Human, Dog, Rat, Hamster. LF-53. Albuquerque, NM: Lovelace Foundation for Medical Education and Research. 1976
Phillips CG and Kaye SR. Diameter-based analysis of the bronchial geometry of four mammalian bronchial trees. Respiration Physiology 102:303-316, 1995
Journal Articles on this Report : 2 Displayed | Download in RIS Format
|Other subproject views:||All 21 publications||13 publications in selected types||All 13 journal articles|
|Other center views:||All 128 publications||71 publications in selected types||All 64 journal articles|
||Lee D, Park SS, Ban-Weiss GA, Fanucchi MV, Plopper CG, Wexler AS. Bifurcation model for characterization of pulmonary architecture. Anatomical Record 2008;291(4):379-389.||
||Tebockhorst S, Lee D, Wexler AS, Oldham MJ. Interaction of epithelium with mesenchyme affects global features of lung architecture: a computer model of development. Journal of Applied Physiology 2007;102(1):294-305.||
Supplemental Keywords:RFA, Health, Scientific Discipline, PHYSICAL ASPECTS, Air, ENVIRONMENTAL MANAGEMENT, particulate matter, Environmental Chemistry, Health Risk Assessment, Risk Assessments, Biochemistry, Physical Processes, Risk Assessment, atmospheric particulate matter, children's health, particle deposition, cardiopulmonary responses, chemical characteristics, human health effects, toxicology, acute cardiovascular effects, exposure, animal model, airborne particulate matter, biological mechanisms, human exposure, PM, particulate matter components, cardiovascular disease, exposure assessment
Progress and Final Reports:Original Abstract
Main Center Abstract and Reports:R832414 San Joaquin Valley Aerosol Health Effects Research Center (SAHERC)
Subprojects under this Center: (EPA does not fund or establish subprojects; EPA awards and manages the overall grant for this center).
R832414C001 Project 1 -- Pulmonary Metabolic Response
R832414C002 Endothelial Cell Responses to PM—In Vitro and In Vivo
R832414C003 Project 3 -- Inhalation Exposure Assessment of San Joaquin Valley Aerosol
R832414C004 Project 4 -- Transport and Fate Particles
R832414C005 Project 5 -- Architecture Development and Particle Deposition