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2007 Progress Report: Project 5 -- Architecture Development and Particle Deposition
EPA Grant Number: R832414C005Subproject: 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
Current Investigators: Wexler, Anthony S. , Schelegle, Ed
Institution: University of California - Davis
EPA Project Officer: Stacey Katz/Gail Robarge,
Project Period: October 1, 2005 through September 30, 2010
Project Period Covered by this Report: October 1, 2006 through September 30, 2007
RFA: Particulate Matter Research Centers (2004)
Research Category: Particulate Matter
Description:
Objective:Quantify lung architecture changes due to pollutant exposure during development.
Progress Summary: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.
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Figure 2. Airway diameter vs Generation |
Figure 3. Asymmetry vs Diameter |
Figure 4. Distribution of twist angle
Future Activities:We will analyze rat lungs exposed to ozone and/or particles, and compare them to normal lungs. Ozone exposures are currently underway.
References:
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: 1 Displayed | Download in RIS Format
| Other subproject views: | All 5 publications | 4 publications in selected types | All 4 journal articles |
| Other center views: | All 19 publications | 10 publications in selected types | All 10 journal articles |
| Type | Citation | ||
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Tebockhorst S, Lee DY, 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. |
R832414C005 (2007) R832414C005 (2008) |
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, ENVIRONMENTAL MANAGEMENT, Air, Scientific Discipline, Health, RFA, PHYSICAL ASPECTS, Risk Assessment, Risk Assessments, Health Risk Assessment, Physical Processes, Biochemistry, particulate matter, Environmental Chemistry, exposure assessment, cardiovascular disease, chemical characteristics, particulate matter components, children's health, cardiopulmonary responses, human health risk, acute cardiovascular effects, human health effects, toxicology, particle deposition, atmospheric particulate matter, exposure, airborne particulate matter, human exposure, PM, animal model
Progress and Final Reports:
2006 Progress Report
Original Abstract
2008 Progress Report
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