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Zhang X, Li F, Rajaraman PK, Comellas AP, Hoffman EA, Lin CL. Investigating distributions of inhaled aerosols in the lungs of post-COVID-19 clusters through a unified imaging and modeling approach. Eur J Pharm Sci 2024; 195:106724. [PMID: 38340875 PMCID: PMC10948263 DOI: 10.1016/j.ejps.2024.106724] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Revised: 02/01/2024] [Accepted: 02/07/2024] [Indexed: 02/12/2024]
Abstract
BACKGROUND Recent studies, based on clinical data, have identified sex and age as significant factors associated with an increased risk of long COVID. These two factors align with the two post-COVID-19 clusters identified by a deep learning algorithm in computed tomography (CT) lung scans: Cluster 1 (C1), comprising predominantly females with small airway diseases, and Cluster 2 (C2), characterized by older individuals with fibrotic-like patterns. This study aims to assess the distributions of inhaled aerosols in these clusters. METHODS 140 COVID survivors examined around 112 days post-diagnosis, along with 105 uninfected, non-smoking healthy controls, were studied. Their demographic data and CT scans at full inspiration and expiration were analyzed using a combined imaging and modeling approach. A subject-specific CT-based computational model analysis was utilized to predict airway resistance and particle deposition among C1 and C2 subjects. The cluster-specific structure and function relationships were explored. RESULTS In C1 subjects, distinctive features included airway narrowing, a reduced homothety ratio of daughter over parent branch diameter, and increased airway resistance. Airway resistance was concentrated in the distal region, with a higher fraction of particle deposition in the proximal airways. On the other hand, C2 subjects exhibited airway dilation, an increased homothety ratio, reduced airway resistance, and a shift of resistance concentration towards the proximal region, allowing for deeper particle penetration into the lungs. CONCLUSIONS This study revealed unique mechanistic phenotypes of airway resistance and particle deposition in the two post-COVID-19 clusters. The implications of these findings for inhaled drug delivery effectiveness and susceptibility to air pollutants were explored.
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Affiliation(s)
- Xuan Zhang
- IIHR-Hydroscience & Engineering, University of Iowa, Iowa City, IA, USA; Department of Mechanical Engineering, University of Iowa, Iowa City, IA, USA
| | - Frank Li
- IIHR-Hydroscience & Engineering, University of Iowa, Iowa City, IA, USA; Roy J. Carver Department of Biomedical Engineering, University of Iowa, Iowa City, IA, USA
| | - Prathish K Rajaraman
- IIHR-Hydroscience & Engineering, University of Iowa, Iowa City, IA, USA; Department of Mechanical Engineering, University of Iowa, Iowa City, IA, USA
| | | | - Eric A Hoffman
- Roy J. Carver Department of Biomedical Engineering, University of Iowa, Iowa City, IA, USA; Department of Radiology, University of Iowa, Iowa City, IA, USA
| | - Ching-Long Lin
- IIHR-Hydroscience & Engineering, University of Iowa, Iowa City, IA, USA; Department of Mechanical Engineering, University of Iowa, Iowa City, IA, USA; Roy J. Carver Department of Biomedical Engineering, University of Iowa, Iowa City, IA, USA; Department of Radiology, University of Iowa, Iowa City, IA, USA.
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2
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Gökcan MK, Kurtuluş DF, Aypak A, Köksal M, Ökten SR. Insights from 3D modeling and fluid dynamics in COVID-19 pneumonia. Med Biol Eng Comput 2024; 62:621-636. [PMID: 37980307 DOI: 10.1007/s11517-023-02958-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Accepted: 10/25/2023] [Indexed: 11/20/2023]
Abstract
We address the lack of research regarding aerodynamic events behind respiratory distress at COVID-19. The use of chest CT enables quantification of pneumonia extent; however, there is a paucity of data regarding the impact of airflow changes. We reviewed 31 COVID-19 patients who were admitted in March 2020 with varying severity of pulmonary disease. Lung volumes were segmented and measured on CT images and patient-specific models of the lungs were created. Incompressible, laminar, and three-dimensional Navier-Stokes equations were used for the fluid dynamics (CFD) analyses of ten patients (five mild, five pneumonia). Of 31 patients, 17 were female, 18 had pneumonia, and 2 were deceased. Effective lung volume decreased in the general group, but the involvement of the right lung was prominent in dyspnea patients. CFD analyses revealed that the mass flow distribution was significantly distorted in pneumonia cases with diminished flow rate towards the right lung. In addition, the distribution of flow parameters showed mild group had less airway resistance with higher velocity (1.228 m/s vs 1.572 m/s) and higher static pressure values at airway branches (1.5112 Pa vs 1.3024 Pa). Therefore, we conclude that airway resistance and mass flow rate distribution are as important as the radiological involvement degree in defining the disease severity.
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Affiliation(s)
- M Kürşat Gökcan
- Otorhinolaryngology, Head and Neck Surgery Department, Ankara University Medical School, Ankara, Turkey.
- Ankara Üniversitesi KBB Hastalıkları Anabilim Dalı, İbni Sina Hastanesi Ek bina K-2, 06100, Sıhhiye, Ankara, Turkey.
| | - D Funda Kurtuluş
- Department of Aerospace Engineering, Faculty of Engineering, Middle East Technical University, Ankara, Turkey
| | - Adalet Aypak
- Department of Infectious Diseases and Clinical Microbiology, Ankara Bilkent City Hospital, Ankara, Turkey
| | - Murathan Köksal
- Department of Radiology, Ankara Bilkent City Hospital, Ankara, Turkey
| | - Sarper R Ökten
- Department of Radiology, Ankara Bilkent City Hospital, Ankara, Turkey
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Spasov G, Rossi R, Vanossi A, Cottini C, Benassi A. A critical analysis of the CFD-DEM simulation of pharmaceutical aerosols deposition in extra-thoracic airways. Int J Pharm 2022; 629:122331. [DOI: 10.1016/j.ijpharm.2022.122331] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Revised: 10/17/2022] [Accepted: 10/18/2022] [Indexed: 11/07/2022]
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Gawthrop PJ, Pan M. Energy-based advection modelling using bond graphs. J R Soc Interface 2022. [PMCID: PMC9554522 DOI: 10.1098/rsif.2022.0492] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Advection, the transport of a substance by the flow of a fluid, is a key process in biological systems. The energy-based bond graph approach to modelling chemical transformation within reaction networks is extended to include transport and thus advection. The approach is illustrated using a simple model of advection via circulating flow and by a simple pharmacokinetic model of anaesthetic gas uptake. This extension provides a physically consistent framework for linking advective flows with the fluxes associated with chemical reactions within the context of physiological systems in general and the human physiome in particular.
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Affiliation(s)
- Peter J. Gawthrop
- Systems Biology Laboratory, School of Mathematics and Statistics, and Department of Biomedical Engineering, University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Michael Pan
- Systems Biology Laboratory, School of Mathematics and Statistics, and Department of Biomedical Engineering, University of Melbourne, Melbourne, Victoria 3010, Australia,School of Mathematics and Statistics, Faculty of Science, University of Melbourne, Melbourne, Victoria 3010, Australia
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5
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Polak AG. Algebraic approximation of the distributed model for the pressure drop in the respiratory airways. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2022; 38:e3632. [PMID: 35648086 DOI: 10.1002/cnm.3632] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Revised: 05/06/2022] [Accepted: 05/28/2022] [Indexed: 06/15/2023]
Abstract
The complexity of the human respiratory system causes that one of the main methods of analyzing the dynamic pulmonary phenomena and interpreting experimental results are simulations of its computational models. Among the most compound elements of these models, apart from the bronchial tree structure, is the phenomenon of flow limitation in flexible bronchi, which causes them to collapse with increasing flow, thus their properties, such as resistance, compliance and inertance, are highly nonlinear and time-varying. Commonly, this phenomenon is ignored, or a distributed model for the airway pressure drop is applied, simulated with a modified numerical solver of this differential equation (ODE). The disadvantages of this solution are the problems with taking into account the inherent singularity of the model and the long computation time due to iterative nature of the ODE procedure. The aim of the work was to derive an algebraic approximation of this distributed model, suitable for implementation in continuous dynamic models, to validate it by comparing the results of simulations with the respiratory system model including approximate and original (ODE solver) numerical procedures, as well as to evaluate possible acceleration of calculations. All simulations, including spontaneous breathing, mechanical ventilation with the optimal ventilatory waveform and forced expiration, proved that algebraic approximation yielded results negligibly differing from the ODE solution, and shortened the computation time by an order. The proposed approach is an attractive alternative in the case of computer implementations of pulmonary models, where simulations of flows and pressures in the complex respiratory system are of primary importance.
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Affiliation(s)
- Adam G Polak
- Department of Electronic and Photonic Metrology, Faculty of Electronics, Photonics and Microsystems, Wrocław University of Science and Technology, Wrocław, Poland
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6
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Rajagopal V, Arumugam S, Hunter PJ, Khadangi A, Chung J, Pan M. The Cell Physiome: What Do We Need in a Computational Physiology Framework for Predicting Single-Cell Biology? Annu Rev Biomed Data Sci 2022; 5:341-366. [PMID: 35576556 DOI: 10.1146/annurev-biodatasci-072018-021246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Modern biology and biomedicine are undergoing a big data explosion, needing advanced computational algorithms to extract mechanistic insights on the physiological state of living cells. We present the motivation for the Cell Physiome project: a framework and approach for creating, sharing, and using biophysics-based computational models of single-cell physiology. Using examples in calcium signaling, bioenergetics, and endosomal trafficking, we highlight the need for spatially detailed, biophysics-based computational models to uncover new mechanisms underlying cell biology. We review progress and challenges to date toward creating cell physiome models. We then introduce bond graphs as an efficient way to create cell physiome models that integrate chemical, mechanical, electromagnetic, and thermal processes while maintaining mass and energy balance. Bond graphs enhance modularization and reusability of computational models of cells at scale. We conclude with a look forward at steps that will help fully realize this exciting new field of mechanistic biomedical data science. Expected final online publication date for the Annual Review of Biomedical Data Science, Volume 5 is August 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Vijay Rajagopal
- Department of Biomedical Engineering, University of Melbourne, Melbourne, Victoria, Australia;
| | - Senthil Arumugam
- Cellular Physiology Lab, Monash Biomedicine Discovery Institute, Faculty of Medicine, Nursing and Health Sciences; European Molecular Biological Laboratory (EMBL) Australia; and Australian Research Council Centre of Excellence in Advanced Molecular Imaging, Monash University, Clayton/Melbourne, Victoria, Australia
| | - Peter J Hunter
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Afshin Khadangi
- Department of Biomedical Engineering, University of Melbourne, Melbourne, Victoria, Australia;
| | - Joshua Chung
- Department of Biomedical Engineering, University of Melbourne, Melbourne, Victoria, Australia;
| | - Michael Pan
- School of Mathematics and Statistics, University of Melbourne, Melbourne, Victoria, Australia
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Hoffman EA. Origins of and lessons from quantitative functional X-ray computed tomography of the lung. Br J Radiol 2022; 95:20211364. [PMID: 35193364 PMCID: PMC9153696 DOI: 10.1259/bjr.20211364] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 01/20/2022] [Accepted: 01/27/2022] [Indexed: 12/16/2022] Open
Abstract
Functional CT of the lung has emerged from quantitative CT (qCT). Structural details extracted at multiple lung volumes offer indices of function. Additionally, single volumetric images, if acquired at standardized lung volumes and body posture, can be used to model function by employing such engineering techniques as computational fluid dynamics. With the emergence of multispectral CT imaging including dual energy from energy integrating CT scanners and multienergy binning using the newly released photon counting CT technology, function is tagged via use of contrast agents. Lung disease phenotypes have previously been lumped together by the limitations of spirometry and plethysmography. QCT and its functional embodiment have been imbedded into studies seeking to characterize chronic obstructive pulmonary disease, severe asthma, interstitial lung disease and more. Reductions in radiation dose by an order of magnitude or more have been achieved. At the same time, we have seen significant increases in spatial and density resolution along with methodologic validations of extracted metrics. Together, these have allowed attention to turn towards more mild forms of disease and younger populations. In early applications, clinical CT offered anatomic details of the lung. Functional CT offers regional measures of lung mechanics, the assessment of functional small airways disease, as well as regional ventilation-perfusion matching (V/Q) and more. This paper will focus on the use of quantitative/functional CT for the non-invasive exploration of dynamic three-dimensional functioning of the breathing lung and beating heart within the unique negative pressure intrathoracic environment of the closed chest.
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Affiliation(s)
- Eric A Hoffman
- Departments of Radiology, Internal Medicine and Biomedical Engineering University of Iowa, Iowa, United States
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Using a Human Circulation Mathematical Model to Simulate the Effects of Hemodialysis and Therapeutic Hypothermia. APPLIED SCIENCES-BASEL 2021. [DOI: 10.3390/app12010307] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Background: We developed a hemodynamic mathematical model of human circulation coupled to a virtual hemodialyzer. The model was used to explore mechanisms underlying our clinical observations involving hemodialysis. Methods: The model consists of whole body human circulation, baroreflex feedback control, and a hemodialyzer. Four model populations encompassing baseline, dialysed, therapeutic hypothermia treated, and simultaneous dialysed with hypothermia were generated. In all populations atrial fibrillation and renal failure as co-morbidities, and exercise as a treatment were simulated. Clinically relevant measurables were used to quantify the effects of each in silico experiment. Sensitivity analysis was used to uncover the most relevant parameters. Results: Relative to baseline, the modelled dialysis increased the population mean diastolic blood pressure by 5%, large vessel wall shear stress by 6%, and heart rate by 20%. Therapeutic hypothermia increased systolic blood pressure by 3%, reduced large vessel shear stress by 15%, and did not affect heart rate. Therapeutic hypothermia reduced wall shear stress by 15% in the aorta and 6% in the kidneys, suggesting a potential anti-inflammatory benefit. Therapeutic hypothermia reduced cardiac output under atrial fibrillation by 12% and under renal failure by 20%. Therapeutic hypothermia and exercise did not affect dialyser function, but increased water removal by approximately 40%. Conclusions: This study illuminates some mechanisms of the action of therapeutic hypothermia. It also suggests clinical measurables that may be used as surrogates to diagnose underlying diseases such as atrial fibrillation.
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Kang JH, Choi J, Chae KJ, Shin KM, Lee CH, Guo J, Lin CL, Hoffman EA, Lee C. CT-derived 3D-diaphragm motion in emphysema and IPF compared to normal subjects. Sci Rep 2021; 11:14923. [PMID: 34290275 PMCID: PMC8295260 DOI: 10.1038/s41598-021-93980-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Accepted: 06/28/2021] [Indexed: 02/06/2023] Open
Abstract
Image registration-based local displacement analysis enables evaluation of respiratory motion between two computed tomography-captured lung volumes. The objective of this study was to compare diaphragm movement among emphysema, idiopathic pulmonary fibrosis (IPF) and normal subjects. 29 normal, 50 emphysema, and 51 IPF subjects were included. A mass preserving image registration technique was used to compute displacement vectors of local lung regions at an acinar scale. Movement of the diaphragm was assumed to be equivalent to movement of the basal lung within 5 mm from the diaphragm. Magnitudes and directions of displacement vectors were compared between the groups. Three-dimensional (3D) and apico-basal displacements were smaller in emphysema than normal subjects (P = 0.003, P = 0.002). Low lung attenuation area on expiration scan showed significant correlations with decreased 3D and apico-basal displacements (r = - 0.546, P < 0.0001; r = - 0.521, P < 0.0001) in emphysema patients. Dorsal-ventral displacement was smaller in IPF than normal subjects (P < 0.0001). The standard deviation of the displacement angle was greater in both emphysema and IPF patients than normal subjects (P < 0.0001). In conclusion, apico-basal movement of the diaphragm is reduced in emphysema while dorsal-ventral movement is reduced in IPF. Image registration technique to multi-volume CT scans provides insight into the pathophysiology of limited diaphragmatic motion in emphysema and IPF.
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Affiliation(s)
- Ji Hee Kang
- Department of Radiology, Konkuk University Medical Center, Seoul, Korea
| | - Jiwoong Choi
- Department of Internal Medicine, School of Medicine, University of Kansas, 3901 Rainbow Blvd, Kansas City, KS, 66160, USA.
- Department of Bioengineering, University of Kansas, Lawrence, KS, USA.
| | - Kum Ju Chae
- Department of Radiology, Jeonbuk National University Hospital, Jeonju, Korea
| | - Kyung Min Shin
- Department of Radiology, Kyungpook National University, Daegu, Korea
| | - Chang-Hoon Lee
- Division of Pulmonary and Critical Care Medicine, Department of Internal Medicine, Seoul National University Hospital, Seoul, South Korea
| | - Junfeng Guo
- Department of Radiology, University of Iowa, Iowa City, IA, USA
- Roy J. Carver Department of Biomedical Engineering, University of Iowa, Iowa City, IA, USA
| | - Ching-Long Lin
- Department of Mechanical Engineering, IIHR-Hydroscience and Engineering, University of Iowa, Iowa City, IA, USA
| | - Eric A Hoffman
- Department of Radiology, University of Iowa, Iowa City, IA, USA
- Roy J. Carver Department of Biomedical Engineering, University of Iowa, Iowa City, IA, USA
- Department of Medicine, University of Iowa, Iowa City, IA, USA
| | - Changhyun Lee
- Department of Radiology, University of Iowa, Iowa City, IA, USA.
- Department of Radiology, Seoul National University College of Medicine, 101 Daehangno, Jongno-gu, Seoul, 03080, Korea.
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Coupled CFD-DEM model for dry powder inhalers simulation: Validation and sensitivity analysis for the main model parameters. POWDER TECHNOL 2021. [DOI: 10.1016/j.powtec.2021.02.044] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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11
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Nagpal P, Guo J, Shin KM, Lim JK, Kim KB, Comellas AP, Kaczka DW, Peterson S, Lee CH, Hoffman EA. Quantitative CT imaging and advanced visualization methods: potential application in novel coronavirus disease 2019 (COVID-19) pneumonia. BJR Open 2021; 3:20200043. [PMID: 33718766 PMCID: PMC7931412 DOI: 10.1259/bjro.20200043] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Revised: 12/01/2020] [Accepted: 12/16/2020] [Indexed: 12/13/2022] Open
Abstract
Increasingly, quantitative lung computed tomography (qCT)-derived metrics are providing novel insights into chronic inflammatory lung diseases, including chronic obstructive pulmonary disease, asthma, interstitial lung disease, and more. Metrics related to parenchymal, airway, and vascular anatomy together with various measures associated with lung function including regional parenchymal mechanics, air trapping associated with functional small airways disease, and dual-energy derived measures of perfused blood volume are offering the ability to characterize disease phenotypes associated with the chronic inflammatory pulmonary diseases. With the emergence of COVID-19, together with its widely varying degrees of severity, its rapid progression in some cases, and the potential for lengthy post-COVID-19 morbidity, there is a new role in applying well-established qCT-based metrics. Based on the utility of qCT tools in other lung diseases, previously validated supervised classical machine learning methods, and emerging unsupervised machine learning and deep-learning approaches, we are now able to provide desperately needed insight into the acute and the chronic phases of this inflammatory lung disease. The potential areas in which qCT imaging can be beneficial include improved accuracy of diagnosis, identification of clinically distinct phenotypes, improvement of disease prognosis, stratification of care, and early objective evaluation of intervention response. There is also a potential role for qCT in evaluating an increasing population of post-COVID-19 lung parenchymal changes such as fibrosis. In this work, we discuss the basis of various lung qCT methods, using case-examples to highlight their potential application as a tool for the exploration and characterization of COVID-19, and offer scanning protocols to serve as templates for imaging the lung such that these established qCT analyses have the best chance at yielding the much needed new insights.
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Affiliation(s)
- Prashant Nagpal
- Department of Radiology, University of Iowa, Carver College of Medicine, Iowa City, IA, USA
| | | | | | - Jae-Kwang Lim
- Department of Radiology, School of Medicine, Kyungpook National University, Daegu, South Korea
| | - Ki Beom Kim
- Department of Radiology, Daegu Fatima Hospital, Daegu, South Korea
| | - Alejandro P Comellas
- Department of Internal Medicine, University of Iowa, Carver College of Medicine, Iowa City, IA, USA
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Christou S, Chatziathanasiou T, Angeli S, Koullapis P, Stylianou F, Sznitman J, Guo HH, Kassinos SC. Anatomical variability in the upper tracheobronchial tree: sex-based differences and implications for personalized inhalation therapies. J Appl Physiol (1985) 2020; 130:678-707. [PMID: 33180641 DOI: 10.1152/japplphysiol.00144.2020] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The morphometry of the large conducting airways is presumed to have a strong effect on the regional deposition of inhaled aerosol particles. Nevertheless, sex-based differences have not been fully quantified and are still largely ignored in designing inhalation therapies. To this end, we retrospectively analyzed high-resolution computed tomography scans for 185 individuals (90 women, 95 men) in the age range of 12-89 yr to determine airway luminal areas, airway lengths, and bifurcation angles. Only subjects free of chronic airway disease were considered. In men, luminal areas of the upper conducting airways were, on average, ∼30%-50% larger when compared with those in women, with the largest differences found in the trachea (289.72 ± 54.25 vs. 193.50 ± 42.37 mm2 for men and women, respectively). The ratio of the largest luminal area in men to the smallest luminal area in women (in any given segment) ranged between 4.5 and 8.6, the largest differences being found in the lobar bronchi. Sex-based differences were minor in the case of bifurcation angles (e.g., average main bifurcation angle: 93.04 ± 9.58° vs. 91.03 ± 9.81° for men and women, respectively), but large intersubject variability was found irrespective of sex (e.g., range of main bifurcation angle: 65.04°-122.01° vs. 69.46°-113.94° for men and women, respectively). Bronchial segments were shorter by ∼5%-20% in women relative to men, the largest differences being located in the upper lobes. False discovery rate analysis revealed statistically significant associations among morphometric measures of the right lung in women (but not in men), suggesting two phenotypes among women that we attribute to the smaller female thoracic volume.NEW & NOTEWORTHY We found significant sex-based morphometric differences in the central airways of healthy men and women that were only mildly attenuated in subsets matched for lung volume. Lumen areas were significantly larger in men (∼30%-50%). Large variability (∼75%-87%) in airway bifurcation angles (60°-122°) was found irrespective of sex. The branching pattern of the right main and right upper bronchi in women (but not in men) follows two phenotypes modulated by lung volume.
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Affiliation(s)
- Simoni Christou
- Computational Sciences Laboratory (UCY-CompSci), Department of Mechanical and Manufacturing Engineering, University of Cyprus, Nicosia, Cyprus
| | - Thanasis Chatziathanasiou
- Computational Sciences Laboratory (UCY-CompSci), Department of Mechanical and Manufacturing Engineering, University of Cyprus, Nicosia, Cyprus
| | | | - Pantelis Koullapis
- Computational Sciences Laboratory (UCY-CompSci), Department of Mechanical and Manufacturing Engineering, University of Cyprus, Nicosia, Cyprus
| | - Fotos Stylianou
- Computational Sciences Laboratory (UCY-CompSci), Department of Mechanical and Manufacturing Engineering, University of Cyprus, Nicosia, Cyprus
| | - Josué Sznitman
- Department of Biomedical Engineering, Technion-Israel Institute of Technology, Haifa, Israel
| | - Haiwei Henry Guo
- Department of Radiology, Stanford University School of Medicine, Stanford, California
| | - Stavros C Kassinos
- Computational Sciences Laboratory (UCY-CompSci), Department of Mechanical and Manufacturing Engineering, University of Cyprus, Nicosia, Cyprus
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A Review of Respiratory Anatomical Development, Air Flow Characterization and Particle Deposition. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:ijerph17020380. [PMID: 31935991 PMCID: PMC7014067 DOI: 10.3390/ijerph17020380] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 12/31/2019] [Accepted: 12/31/2019] [Indexed: 12/20/2022]
Abstract
The understanding of complex inhalation and transport processes of pollutant particles through the human respiratory system is important for investigations into dosimetry and respiratory health effects in various settings, such as environmental or occupational health. The studies over the last few decades for micro- and nanoparticle transport and deposition have advanced the understanding of drug-aerosol impacts in the mouth-throat and the upper airways. However, most of the Lagrangian and Eulerian studies have utilized the non-realistic symmetric anatomical model for airflow and particle deposition predictions. Recent improvements to visualization techniques using high-resolution computed tomography (CT) data and the resultant development of three dimensional (3-D) anatomical models support the realistic representation of lung geometry. Yet, the selection of different modelling approaches to analyze the transitional flow behavior and the use of different inlet and outlet conditions provide a dissimilar prediction of particle deposition in the human lung. Moreover, incorporation of relevant physical and appropriate boundary conditions are important factors to consider for the more accurate prediction of transitional flow and particle transport in human lung. This review critically appraises currently available literature on airflow and particle transport mechanism in the lungs, as well as numerical simulations with the aim to explore processes involved. Numerical studies found that both the Euler–Lagrange (E-L) and Euler–Euler methods do not influence nanoparticle (particle diameter ≤50 nm) deposition patterns at a flow rate ≤25 L/min. Furthermore, numerical studies demonstrated that turbulence dispersion does not significantly affect nanoparticle deposition patterns. This critical review aims to develop the field and increase the state-of-the-art in human lung modelling.
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Gu Q, Qi S, Yue Y, Shen J, Zhang B, Sun W, Qian W, Islam MS, Saha SC, Wu J. Structural and functional alterations of the tracheobronchial tree after left upper pulmonary lobectomy for lung cancer. Biomed Eng Online 2019; 18:105. [PMID: 31653252 PMCID: PMC6815003 DOI: 10.1186/s12938-019-0722-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Accepted: 10/15/2019] [Indexed: 12/18/2022] Open
Abstract
Background Pulmonary lobectomy has been a well-established curative treatment method for localized lung cancer. After left upper pulmonary lobectomy, the upward displacement of remaining lower lobe causes the distortion or kink of bronchus, which is associated with intractable cough and breathless. However, the quantitative study on structural and functional alterations of the tracheobronchial tree after lobectomy has not been reported. We sought to investigate these alterations using CT imaging analysis and computational fluid dynamics (CFD) method. Methods Both preoperative and postoperative CT images of 18 patients who underwent left upper pulmonary lobectomy are collected. After the tracheobronchial tree models are extracted, the angles between trachea and bronchi, the surface area and volume of the tree, and the cross-sectional area of left lower lobar bronchus are investigated. CFD method is further used to describe the airflow characteristics by the wall pressure, airflow velocity, lobar flow rate, etc. Results It is found that the angle between the trachea and the right main bronchus increases after operation, but the angle with the left main bronchus decreases. No significant alteration is observed for the surface area or volume of the tree between pre-operation and post-operation. After left upper pulmonary lobectomy, the cross-sectional area of left lower lobar bronchus is reduced for most of the patients (15/18) by 15–75%, especially for 4 patients by more than 50%. The wall pressure, airflow velocity and pressure drop significantly increase after the operation. The flow rate to the right lung increases significantly by 2–30% (but there is no significant difference between each lobe), and the flow rate to the left lung drops accordingly. Many vortices are found in various places with severe distortions. Conclusions The favorable and unfavorable adaptive alterations of tracheobronchial tree will occur after left upper pulmonary lobectomy, and these alterations can be clarified through CT imaging and CFD analysis. The severe distortions at left lower lobar bronchus might exacerbate postoperative shortness of breath.
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Affiliation(s)
- Qingtao Gu
- Sino-Dutch Biomedical and Information Engineering School, Northeastern University, Shenyang, China.,Key Laboratory of Medical Image Computing of Northeastern University (Ministry of Education), Shenyang, China
| | - Shouliang Qi
- Sino-Dutch Biomedical and Information Engineering School, Northeastern University, Shenyang, China. .,Key Laboratory of Medical Image Computing of Northeastern University (Ministry of Education), Shenyang, China.
| | - Yong Yue
- Department of Radiology, Shengjing Hospital of China Medical University, Shenyang, China
| | - Jing Shen
- Department of Radiology, Affiliated Zhongshan Hospital of Dalian University, Dalian, China
| | - Baihua Zhang
- Sino-Dutch Biomedical and Information Engineering School, Northeastern University, Shenyang, China
| | - Wei Sun
- The Graduate School, Dalian Medical University, Dalian, China
| | - Wei Qian
- Sino-Dutch Biomedical and Information Engineering School, Northeastern University, Shenyang, China.,College of Engineering, University of Texas at El Paso, El Paso, USA
| | - Mohammad Saidul Islam
- School of Mechanical and Mechatronic Engineering, Faculty of Engineering and Information Technology, University of Technology Sydney, Brisbane, Australia
| | - Suvash C Saha
- School of Mechanical and Mechatronic Engineering, Faculty of Engineering and Information Technology, University of Technology Sydney, Brisbane, Australia
| | - Jianlin Wu
- Department of Radiology, Affiliated Zhongshan Hospital of Dalian University, Dalian, China.
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15
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Schiebler ML, Parraga G. Visualization of the Small Airways:What It Is and Why It Matters. Radiology 2019; 293:674-675. [PMID: 31617816 DOI: 10.1148/radiol.2019192025] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Affiliation(s)
- Mark L Schiebler
- From the Department of Radiology, Professor of Cardiothoracic Radiology, University of Wisconsin School of Medicine and Public Health, 600 Highland Ave, Madison, WI 53792-3252 (M.L.S.); and Department of Medical Biophysics and Robarts Research Institute, Western University, London, Canada (G.P.)
| | - Grace Parraga
- From the Department of Radiology, Professor of Cardiothoracic Radiology, University of Wisconsin School of Medicine and Public Health, 600 Highland Ave, Madison, WI 53792-3252 (M.L.S.); and Department of Medical Biophysics and Robarts Research Institute, Western University, London, Canada (G.P.)
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16
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Sul B, Oppito Z, Jayasekera S, Vanger B, Zeller A, Morris M, Ruppert K, Altes T, Rakesh V, Day S, Robinson R, Reifman J, Wallqvist A. Assessing Airflow Sensitivity to Healthy and Diseased Lung Conditions in a Computational Fluid Dynamics Model Validated In Vitro. J Biomech Eng 2019; 140:2668581. [PMID: 29305603 DOI: 10.1115/1.4038896] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Indexed: 12/16/2022]
Abstract
Computational models are useful for understanding respiratory physiology. Crucial to such models are the boundary conditions specifying the flow conditions at truncated airway branches (terminal flow rates). However, most studies make assumptions about these values, which are difficult to obtain in vivo. We developed a computational fluid dynamics (CFD) model of airflows for steady expiration to investigate how terminal flows affect airflow patterns in respiratory airways. First, we measured in vitro airflow patterns in a physical airway model, using particle image velocimetry (PIV). The measured and computed airflow patterns agreed well, validating our CFD model. Next, we used the lobar flow fractions from a healthy or chronic obstructive pulmonary disease (COPD) subject as constraints to derive different terminal flow rates (i.e., three healthy and one COPD) and computed the corresponding airflow patterns in the same geometry. To assess airflow sensitivity to the boundary conditions, we used the correlation coefficient of the shape similarity (R) and the root-mean-square of the velocity magnitude difference (Drms) between two velocity contours. Airflow patterns in the central airways were similar across healthy conditions (minimum R, 0.80) despite variations in terminal flow rates but markedly different for COPD (minimum R, 0.26; maximum Drms, ten times that of healthy cases). In contrast, those in the upper airway were similar for all cases. Our findings quantify how variability in terminal and lobar flows contributes to airflow patterns in respiratory airways. They highlight the importance of using lobar flow fractions to examine physiologically relevant airflow characteristics.
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Affiliation(s)
- Bora Sul
- Department of Defense Biotechnology High Performance Computing Software Applications Institute, Telemedicine and Advanced Technology Research Center, United States Army Medical Research and Materiel Command, Fort Detrick, MD 21702
| | - Zachary Oppito
- Mechanical Engineering Department, Rochester Institute of Technology, Rochester, NY 14623
| | - Shehan Jayasekera
- Mechanical Engineering Department, Rochester Institute of Technology, Rochester, NY 14623
| | - Brian Vanger
- Mechanical Engineering Department, Rochester Institute of Technology, Rochester, NY 14623
| | - Amy Zeller
- Mechanical Engineering Department, Rochester Institute of Technology, Rochester, NY 14623
| | - Michael Morris
- Department of Medicine, San Antonio Military Medical Center, JBSA Fort Sam Houston, San Antonio, TX 78234
| | - Kai Ruppert
- Radiology Department, University of Pennsylvania, Philadelphia, PA 19104
| | - Talissa Altes
- Department of Radiology, University of Missouri, Columbia, MO 65211
| | - Vineet Rakesh
- Department of Defense Biotechnology High Performance Computing Software Applications Institute, Telemedicine and Advanced Technology Research Center, United States Army Medical Research and Materiel Command, Fort Detrick, MD 21702
| | - Steven Day
- Mechanical Engineering Department, Rochester Institute of Technology, Rochester, NY 14623
| | - Risa Robinson
- Mechanical Engineering Department, Rochester Institute of Technology, Rochester, NY 14623
| | - Jaques Reifman
- Department of Defense Biotechnology High Performance Computing Software Applications Institute, Telemedicine and Advanced Technology Research Center, United States Army Medical Research and Materiel Command, Fort Detrick, MD 21702 e-mail:
| | - Anders Wallqvist
- Department of Defense Biotechnology High Performance Computing Software Applications Institute, Telemedicine and Advanced Technology Research Center, United States Army Medical Research and Materiel Command, Fort Detrick, MD 21702
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17
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Walenga RL, Babiskin AH, Zhao L. In Silico Methods for Development of Generic Drug-Device Combination Orally Inhaled Drug Products. CPT-PHARMACOMETRICS & SYSTEMS PHARMACOLOGY 2019; 8:359-370. [PMID: 31044532 PMCID: PMC6618094 DOI: 10.1002/psp4.12413] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Accepted: 04/07/2019] [Indexed: 12/03/2022]
Abstract
The development of generic, single‐entity, drug–device combination products for orally inhaled drug products is challenging in part because of the complex nature of device design characteristics and the difficulties associated with establishing bioequivalence for a locally acting drug product delivered to the site of action in the lung. This review examines in silico models that may be used to support the development of generic orally inhaled drug products and how model credibility may be assessed.
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Affiliation(s)
- Ross L Walenga
- Division of Quantitative Methods and Modeling, Office of Research and Standards, Office of Generic Drugs, Center for Drug Evaluation and Research, US Food and Drug Administration, Silver Spring, Maryland, USA
| | - Andrew H Babiskin
- Division of Quantitative Methods and Modeling, Office of Research and Standards, Office of Generic Drugs, Center for Drug Evaluation and Research, US Food and Drug Administration, Silver Spring, Maryland, USA
| | - Liang Zhao
- Division of Quantitative Methods and Modeling, Office of Research and Standards, Office of Generic Drugs, Center for Drug Evaluation and Research, US Food and Drug Administration, Silver Spring, Maryland, USA
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18
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Longest PW, Bass K, Dutta R, Rani V, Thomas ML, El-Achwah A, Hindle M. Use of computational fluid dynamics deposition modeling in respiratory drug delivery. Expert Opin Drug Deliv 2019; 16:7-26. [PMID: 30463458 PMCID: PMC6529297 DOI: 10.1080/17425247.2019.1551875] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Accepted: 11/20/2018] [Indexed: 10/27/2022]
Abstract
INTRODUCTION Respiratory drug delivery is a surprisingly complex process with a number of physical and biological challenges. Computational fluid dynamics (CFD) is a scientific simulation technique that is capable of providing spatially and temporally resolved predictions of many aspects related to respiratory drug delivery from initial aerosol formation through respiratory cellular drug absorption. AREAS COVERED This review article focuses on CFD-based deposition modeling applied to pharmaceutical aerosols. Areas covered include the development of new complete-airway CFD deposition models and the application of these models to develop a next-generation of respiratory drug delivery strategies. EXPERT OPINION Complete-airway deposition modeling is a valuable research tool that can improve our understanding of pharmaceutical aerosol delivery and is already supporting medical hypotheses, such as the expected under-treatment of the small airways in asthma. These complete-airway models are also being used to advance next-generation aerosol delivery strategies, like controlled condensational growth. We envision future applications of CFD deposition modeling to reduce the need for human subject testing in developing new devices and formulations, to help establish bioequivalence for the accelerated approval of generic inhalers, and to provide valuable new insights related to drug dissolution and clearance leading to microdosimetry maps of drug absorption.
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Affiliation(s)
- P. Worth Longest
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, VA, USA
- Department of Pharmaceutics, Virginia Commonwealth University, Richmond, VA, USA
| | - Karl Bass
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, VA, USA
| | - Rabijit Dutta
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, VA, USA
| | - Vijaya Rani
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, VA, USA
| | - Morgan L. Thomas
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, VA, USA
| | - Ahmad El-Achwah
- Department of Mechanical and Nuclear Engineering, Virginia Commonwealth University, Richmond, VA, USA
| | - Michael Hindle
- Department of Pharmaceutics, Virginia Commonwealth University, Richmond, VA, USA
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19
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Zhang B, Qi S, Yue Y, Shen J, Li C, Qian W, Wu J. Particle Disposition in the Realistic Airway Tree Models of Subjects with Tracheal Bronchus and COPD. BIOMED RESEARCH INTERNATIONAL 2018; 2018:7428609. [PMID: 30155481 PMCID: PMC6098871 DOI: 10.1155/2018/7428609] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/17/2018] [Revised: 07/02/2018] [Accepted: 07/18/2018] [Indexed: 12/31/2022]
Abstract
Dispositions of inhalable particles in the human respiratory tract trigger and exacerbate airway inflammatory diseases. However, the particle deposition (PD) in airway of subjects with tracheal bronchus (TB) and chronic obstructive pulmonary diseases (COPD) is unknown. We therefore propose to clarify the disrupted PD associated with TB and COPD using the computational fluid dynamics (CFD) simulation. Totally nine airway tree models are included. Six are extracted from CT images of different individuals (two with TB, two with COPD, and two healthy controls (HC)). The others are the artificially modified models (AMMs) generated by the virtual lesion. Specifically, they are constructed through artificially adding a tracheal bronchus or a stenosis on one HC model. The deposition efficiency (DE) and deposition fraction (DF) in these models are obtained by the Euler-Lagrange approach, analyzed, and compared across models, locations, and particle sizes (0.1-10.0 micrometers). It is found that the PD in models with TB and COPD has been disrupted by the geometrical changes and followed airflow alternations. DE of the tracheal bronchus is higher for TB models. For COPD, the stenosis location determines the effects on DE and DF. Higher DF at the trachea is observed in TB1, TB2, and COPD2 models. DE increases with the particle size, and DE of the terminal bronchi is higher than that of central regions. Combined with AMMs, the CFD simulation using realistic airway models demonstrates disruptions of DP. The methods and findings might help understand the etiology of pulmonary diseases and improve the efficacy of inhaled medicines.
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Affiliation(s)
- Baihua Zhang
- Sino-Dutch Biomedical and Information Engineering School, Northeastern University, Shenyang, China
- Key Laboratory of Medical Image Computing of Northeastern University (Ministry of Education), Shenyang, China
| | - Shouliang Qi
- Sino-Dutch Biomedical and Information Engineering School, Northeastern University, Shenyang, China
- Key Laboratory of Medical Image Computing of Northeastern University (Ministry of Education), Shenyang, China
| | - Yong Yue
- Department of Radiology, ShengJing Hospital of China Medical University, Shenyang, China
| | - Jing Shen
- Department of Radiology, Affiliated Zhongshan Hospital of Dalian University, Dalian, China
| | - Chen Li
- Sino-Dutch Biomedical and Information Engineering School, Northeastern University, Shenyang, China
| | - Wei Qian
- Sino-Dutch Biomedical and Information Engineering School, Northeastern University, Shenyang, China
- College of Engineering, University of Texas at El Paso, El Paso, USA
| | - Jianlin Wu
- Department of Radiology, Affiliated Zhongshan Hospital of Dalian University, Dalian, China
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20
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Tenenbaum-Katan J, Artzy-Schnirman A, Fishler R, Korin N, Sznitman J. Biomimetics of the pulmonary environment in vitro: A microfluidics perspective. BIOMICROFLUIDICS 2018; 12:042209. [PMID: 29887933 PMCID: PMC5973897 DOI: 10.1063/1.5023034] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2018] [Accepted: 03/20/2018] [Indexed: 05/08/2023]
Abstract
The entire luminal surface of the lungs is populated with a complex yet confluent, uninterrupted airway epithelium in conjunction with an extracellular liquid lining layer that creates the air-liquid interface (ALI), a critical feature of healthy lungs. Motivated by lung disease modelling, cytotoxicity studies, and drug delivery assessments amongst other, in vitro setups have been traditionally conducted using macroscopic cultures of isolated airway cells under submerged conditions or instead using transwell inserts with permeable membranes to model the ALI architecture. Yet, such strategies continue to fall short of delivering a sufficiently realistic physiological in vitro airway environment that cohesively integrates at true-scale three essential pillars: morphological constraints (i.e., airway anatomy), physiological conditions (e.g., respiratory airflows), and biological functionality (e.g., cellular makeup). With the advent of microfluidic lung-on-chips, there have been tremendous efforts towards designing biomimetic airway models of the epithelial barrier, including the ALI, and leveraging such in vitro scaffolds as a gateway for pulmonary disease modelling and drug screening assays. Here, we review in vitro platforms mimicking the pulmonary environment and identify ongoing challenges in reconstituting accurate biological airway barriers that still widely prevent microfluidic systems from delivering mainstream assays for the end-user, as compared to macroscale in vitro cell cultures. We further discuss existing hurdles in scaling up current lung-on-chip designs, from single airway models to more physiologically realistic airway environments that are anticipated to deliver increasingly meaningful whole-organ functions, with an outlook on translational and precision medicine.
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Affiliation(s)
- Janna Tenenbaum-Katan
- Department of Biomedical Engineering, Technion–Israel Institute of Technology, 32000 Haifa, Israel
| | - Arbel Artzy-Schnirman
- Department of Biomedical Engineering, Technion–Israel Institute of Technology, 32000 Haifa, Israel
| | - Rami Fishler
- Department of Biomedical Engineering, Technion–Israel Institute of Technology, 32000 Haifa, Israel
| | - Netanel Korin
- Department of Biomedical Engineering, Technion–Israel Institute of Technology, 32000 Haifa, Israel
| | - Josué Sznitman
- Department of Biomedical Engineering, Technion–Israel Institute of Technology, 32000 Haifa, Israel
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21
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Shang Y, Tian L, Fan Y, Dong J, Inthavong K, Tu J. Effect of morphology on nanoparticle transport and deposition in human upper tracheobronchial airways. ACTA ACUST UNITED AC 2018. [DOI: 10.1177/1757482x18756012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Aerosol transport and deposition in human lungs has attracted considerable attention in the past few years, as it has significant value to the study of toxicity consequence as well as therapeutic potential in occupational health and medical applications. In reproducing human tracheobronchial airways, two approaches were frequently taken: (1) anatomical realistic reconstruction through image scans (e.g. CT and MRI) or cadaver casts and (2) mathematical description using simplified models. Strengths and limitations are primarily focused on accuracy, resolution, repeatability, and computational\physical expenses. While both approaches were reported in literature, detailed comparison of aerosol transport and deposition in the two representations were scarcely performed, largely due to the challenge to acquire comprehensive data from the irregular structured airway replicas (approach 1). To fill the gap, the current study performed a numerical comparison of nanoparticle transport and deposition in human upper tracheobronchial airways by using an anatomical realistic reconstruction (through CT scans) and a mathematically simplified airway model. As the first step, the current study was focused on the variation in breathing airflow pattern and the effect towards fate of the inhaled nanoparticles in human upper tracheobronchial airways. The study provided important information to understand geometric sensitivity of nanoparticle modeling in the human tracheobronchial tree and is of significant value to predict the whole lung uptake of inhaled nanoparticles in the human respiratory system.
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Affiliation(s)
- Yidan Shang
- School of Engineering – Mechanical and Automotive, RMIT University, Bundoora, Australia
| | - Lin Tian
- School of Engineering – Mechanical and Automotive, RMIT University, Bundoora, Australia
| | - Yaming Fan
- College of Ecological Environment and Urban Construction, Fujian University of Technology, Fuzhou, China
| | - Jingliang Dong
- School of Engineering – Mechanical and Automotive, RMIT University, Bundoora, Australia
| | - Kiao Inthavong
- School of Engineering – Mechanical and Automotive, RMIT University, Bundoora, Australia
| | - Jiyuan Tu
- School of Engineering – Mechanical and Automotive, RMIT University, Bundoora, Australia
- Key Laboratory of Ministry of Education for Advanced Reactor Engineering and Safety, Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing, China
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22
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Insulation fiber deposition in the airways of men and rats. A review of experimental and computational studies. Regul Toxicol Pharmacol 2018; 94:252-270. [PMID: 29444452 DOI: 10.1016/j.yrtph.2018.01.021] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Revised: 01/07/2018] [Accepted: 01/24/2018] [Indexed: 12/22/2022]
Abstract
The typical insulation rock, slag and glass wool fibers are high volume materials. Current exposure levels in industry (generally ≤ 1 fiber/cm3 with a median diameter ∼1 μm and length ≥10 μm) are not considered carcinogenic or causing other types of severe lung effects. However, epidemiological studies are not informative on effects in humans at fiber levels >1 fiber/cm3. Effects may be inferred from valid rat studies, conducted with rat respirable fibers (diameter ≤ 1.5 μm). Therefore, we estimate delivery and deposition in human and rat airways of the industrial fibers. The deposition fractions in humans head regions by nasal (∼0.20) and by mouth breathing (≤0.08) are lower than in rats (0.50). The delivered dose into the lungs per unit lung surface area during a 1-day exposure at a similar air concentration is estimated to be about two times higher in humans than in rats. The deposition fractions in human lungs by nasal (∼0.20) and by mouth breathing (∼0.40) are higher than in rats (∼0.04). The human lung deposition may be up to three times by nasal breathing and up to six times higher by oral breathing than in rats, qualifying assessment factor setting for deposition.
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23
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Lalas A, Nousias S, Kikidis D, Lalos A, Arvanitis G, Sougles C, Moustakas K, Votis K, Verbanck S, Usmani O, Tzovaras D. Substance deposition assessment in obstructed pulmonary system through numerical characterization of airflow and inhaled particles attributes. BMC Med Inform Decis Mak 2017; 17:173. [PMID: 29297393 PMCID: PMC5751792 DOI: 10.1186/s12911-017-0561-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND Chronic obstructive pulmonary disease (COPD) and asthma are considered as the two most widespread obstructive lung diseases, whereas they affect more than 500 million people worldwide. Unfortunately, the requirement for detailed geometric models of the lungs in combination with the increased computational resources needed for the simulation of the breathing did not allow great progress to be made in the past for the better understanding of inflammatory diseases of the airways through detailed modelling approaches. In this context, computational fluid dynamics (CFD) simulations accompanied by fluid particle tracing (FPT) analysis of the inhaled ambient particles are deemed critical for lung function assessment. Also they enable the understanding of particle depositions on the airways of patients, since these accumulations may affect or lead to inflammations. In this direction, the current study conducts an initial investigation for the better comprehension of particle deposition within the lungs. More specifically, accurate models of the airways obstructions that relate to pulmonary disease are developed and a thorough assessment of the airflow behavior together with identification of the effects of inhaled particle properties, such as size and density, is conducted. Our approach presents a first step towards an effective personalization of pulmonary treatment in regards to the geometric characteristics of the lungs and the in depth understanding of airflows within the airways. METHODS A geometry processing technique involving contraction algorithms is established and used to employ the different respiratory arrangements associated with lung related diseases that exhibit airways obstructions. Apart from the normal lung case, two categories of obstructed cases are examined, i.e. models with obstructions in both lungs and models with narrowings in the right lung only. Precise assumptions regarding airflow and deposition fraction (DF) over various sections of the lungs are drawn by simulating these distinct incidents through the finite volume method (FVM) and particularly the CFD and FPT algorithms. Moreover, a detailed parametric analysis clarifies the effects of the particles size and density in terms of regional deposition upon several parts of the pulmonary system. In this manner, the deposition pattern of various substances can be assessed. RESULTS For the specific case of the unobstructed lung model most particles are detected on the right lung (48.56% of total, when the air flowrate is 12.6 L/min), a fact that is also true when obstructions arise symmetrically in both lungs (51.45% of total, when the air flowrate is 6.06 L/min and obstructions occur after the second generation). In contrast, when narrowings are developed on the right lung only, most particles are pushed on the left section (68.22% of total, when the air flowrate is 11.2 L/min) indicating that inhaled medication is generally deposited away from the areas of inflammation. This observation is useful when designing medical treatment of lung diseases. Furthermore, particles with diameters from 1 μm to 10 μm are shown to be mainly deposited on the lower airways, whereas particles with diameters of 20 μm and 30 μm are mostly accumulated in the upper airways. As a result, the current analysis indicates increased DF levels in the upper airways when the particle diameter is enlarged. Additionally, when the particles density increases from 1000 Kg/m3 to 2000 Kg/m3, the DF is enhanced on every generation and for all cases investigated herein. The results obtained by our simulations provide an accurate and quantitative estimation of all important parameters involved in lung modeling. CONCLUSIONS The treatment of respiratory diseases with inhaled medical substances can be advanced by the clinical use of accurate CFD and FPT simulations and specifically by evaluating the deposition of inhaled particles in a regional oriented perspective in regards to different particle sizes and particle densities. Since a drug with specific characteristics (i.e. particle size and density) exhibits maximum deposition on particular lung areas, the current study provides initial indications to a qualified physician for proper selection of medication.
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Affiliation(s)
- Antonios Lalas
- Information Technologies Institute, Centre for Research and Technology - Hellas (CERTH), Thessaloniki, Greece.
| | - Stavros Nousias
- Department of Electrical and Computer Engineering, University of Patras, Patra, Greece
| | - Dimitrios Kikidis
- Information Technologies Institute, Centre for Research and Technology - Hellas (CERTH), Thessaloniki, Greece
| | - Aris Lalos
- Department of Electrical and Computer Engineering, University of Patras, Patra, Greece
| | - Gerasimos Arvanitis
- Department of Electrical and Computer Engineering, University of Patras, Patra, Greece
| | - Christos Sougles
- Information Technologies Institute, Centre for Research and Technology - Hellas (CERTH), Thessaloniki, Greece
| | | | - Konstantinos Votis
- Information Technologies Institute, Centre for Research and Technology - Hellas (CERTH), Thessaloniki, Greece
| | - Sylvia Verbanck
- Respiratory Division, University Hospital UZ Brussel, Vrije Universiteit Brussel, Brussels, Belgium
| | - Omar Usmani
- National Heart and Lung Institute (NHLI), Imperial College London and Royal Brompton Hospital, London, UK
| | - Dimitrios Tzovaras
- Information Technologies Institute, Centre for Research and Technology - Hellas (CERTH), Thessaloniki, Greece
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24
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Qi S, Zhang B, Teng Y, Li J, Yue Y, Kang Y, Qian W. Transient Dynamics Simulation of Airflow in a CT-Scanned Human Airway Tree: More or Fewer Terminal Bronchi? COMPUTATIONAL AND MATHEMATICAL METHODS IN MEDICINE 2017; 2017:1969023. [PMID: 29333194 PMCID: PMC5733160 DOI: 10.1155/2017/1969023] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/01/2017] [Revised: 08/29/2017] [Accepted: 11/05/2017] [Indexed: 01/09/2023]
Abstract
Using computational fluid dynamics (CFD) method, the feasibility of simulating transient airflow in a CT-based airway tree with more than 100 outlets for a whole respiratory period is studied, and the influence of truncations of terminal bronchi on CFD characteristics is investigated. After an airway model with 122 outlets is extracted from CT images, the transient airflow is simulated. Spatial and temporal variations of flow velocity, wall pressure, and wall shear stress are presented; the flow pattern and lobar distribution of air are gotten as well. All results are compared with those of a truncated model with 22 outlets. It is found that the flow pattern shows lobar heterogeneity that the near-wall air in the trachea is inhaled into the upper lobe while the center flow enters the other lobes, and the lobar distribution of air is significantly correlated with the outlet area ratio. The truncation decreases airflow to right and left upper lobes and increases the deviation of airflow distributions between inspiration and expiration. Simulating the transient airflow in an airway tree model with 122 bronchi using CFD is feasible. The model with more terminal bronchi decreases the difference between the lobar distributions at inspiration and at expiration.
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Affiliation(s)
- Shouliang Qi
- Sino-Dutch Biomedical and Information Engineering School, Northeastern University, Shenyang, China
- Key Laboratory of Medical Image Computing, Northeastern University, Ministry of Education, Shenyang, China
| | - Baihua Zhang
- Sino-Dutch Biomedical and Information Engineering School, Northeastern University, Shenyang, China
- Key Laboratory of Medical Image Computing, Northeastern University, Ministry of Education, Shenyang, China
| | - Yueyang Teng
- Sino-Dutch Biomedical and Information Engineering School, Northeastern University, Shenyang, China
- Key Laboratory of Medical Image Computing, Northeastern University, Ministry of Education, Shenyang, China
| | - Jianhua Li
- Sino-Dutch Biomedical and Information Engineering School, Northeastern University, Shenyang, China
- Key Laboratory of Medical Image Computing, Northeastern University, Ministry of Education, Shenyang, China
| | - Yong Yue
- Department of Radiology, Shengjing Hospital of China Medical University, Shenyang, China
| | - Yan Kang
- Sino-Dutch Biomedical and Information Engineering School, Northeastern University, Shenyang, China
- Key Laboratory of Medical Image Computing, Northeastern University, Ministry of Education, Shenyang, China
| | - Wei Qian
- Sino-Dutch Biomedical and Information Engineering School, Northeastern University, Shenyang, China
- College of Engineering, University of Texas, El Paso, TX, USA
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25
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Abstract
Respiratory disease is a significant problem worldwide, and it is a problem with increasing prevalence. Pathology in the upper airways and lung is very difficult to diagnose and treat, as response to disease is often heterogeneous across patients. Computational models have long been used to help understand respiratory function, and these models have evolved alongside increases in the resolution of medical imaging and increased capability of functional imaging, advances in biological knowledge, mathematical techniques and computational power. The benefits of increasingly complex and realistic geometric and biophysical models of the respiratory system are that they are able to capture heterogeneity in patient response to disease and predict emergent function across spatial scales from the delicate alveolar structures to the whole organ level. However, with increasing complexity, models become harder to solve and in some cases harder to validate, which can reduce their impact clinically. Here, we review the evolution of complexity in computational models of the respiratory system, including successes in translation of models into the clinical arena. We also highlight major challenges in modelling the respiratory system, while making use of the evolving functional data that are available for model parameterisation and testing.
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Affiliation(s)
- Alys R Clark
- 1 Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
| | - Haribalan Kumar
- 1 Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
| | - Kelly Burrowes
- 2 Department of Chemical and Materials Engineering, The University of Auckland, Auckland, New Zealand
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26
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Choi J, Hoffman EA, Lin CL, Milhem MM, Tessier J, Newell JD. Quantitative computed tomography determined regional lung mechanics in normal nonsmokers, normal smokers and metastatic sarcoma subjects. PLoS One 2017; 12:e0179812. [PMID: 28749945 PMCID: PMC5531492 DOI: 10.1371/journal.pone.0179812] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2016] [Accepted: 06/05/2017] [Indexed: 11/29/2022] Open
Abstract
Objectives Extra-thoracic tumors send out pilot cells that attach to the pulmonary endothelium. We hypothesized that this could alter regional lung mechanics (tissue stiffening or accumulation of fluid and inflammatory cells) through interactions with host cells. We explored this with serial inspiratory computed tomography (CT) and image matching to assess regional changes in lung expansion. Materials and methods We retrospectively assessed 44 pairs of two serial CT scans on 21 sarcoma patients: 12 without lung metastases and 9 with lung metastases. For each subject, two or more serial inspiratory clinically-derived CT scans were retrospectively collected. Two research-derived control groups were included: 7 normal nonsmokers and 12 asymptomatic smokers with two inspiratory scans taken the same day or one year apart respectively. We performed image registration for local-to-local matching scans to baseline, and derived local expansion and density changes at an acinar scale. Welch two sample t test was used for comparison between groups. Statistical significance was determined with a p value < 0.05. Results Lung regions of metastatic sarcoma patients (but not the normal control group) demonstrated an increased proportion of normalized lung expansion between the first and second CT. These hyper-expanded regions were associated with, but not limited to, visible metastatic lung lesions. Compared with the normal control group, the percent of increased normalized hyper-expanded lung in sarcoma subjects was significantly increased (p < 0.05). There was also evidence of increased lung “tissue” volume (non-air components) in the hyper-expanded regions of the cancer subjects relative to non-hyper-expanded regions. “Tissue” volume increase was present in the hyper-expanded regions of metastatic and non-metastatic sarcoma subjects. This putatively could represent regional inflammation related to the presence of tumor pilot cell-host related interactions. Conclusions This new quantitative CT (QCT) method for linking serial acquired inspiratory CT images may provide a diagnostic and prognostic means to objectively characterize regional responses in the lung following oncological treatment and monitoring for lung metastases.
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Affiliation(s)
- Jiwoong Choi
- Departments of Radiology, University of Iowa, Iowa City, Iowa, United States of America
- IIHR-Hydroscience & Engineering, University of Iowa, Iowa City, Iowa, United States of America
| | - Eric A. Hoffman
- Departments of Radiology, University of Iowa, Iowa City, Iowa, United States of America
- Departments of Biomedical Engineering, University of Iowa, Iowa City, Iowa, United States of America
- Departments of Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Ching-Long Lin
- IIHR-Hydroscience & Engineering, University of Iowa, Iowa City, Iowa, United States of America
| | - Mohammed M. Milhem
- Departments of Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Jean Tessier
- Pharma Research and Early Development, Roche Innovation Center, Basel, Switzerland
| | - John D. Newell
- Departments of Radiology, University of Iowa, Iowa City, Iowa, United States of America
- Departments of Biomedical Engineering, University of Iowa, Iowa City, Iowa, United States of America
- * E-mail:
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27
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Burrowes KS, De Backer J, Kumar H. Image-based computational fluid dynamics in the lung: virtual reality or new clinical practice? WILEY INTERDISCIPLINARY REVIEWS-SYSTEMS BIOLOGY AND MEDICINE 2017; 9. [PMID: 28608962 DOI: 10.1002/wsbm.1392] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Revised: 04/12/2017] [Accepted: 04/19/2017] [Indexed: 11/05/2022]
Abstract
The development and implementation of personalized medicine is paramount to improving the efficiency and efficacy of patient care. In the respiratory system, function is largely dictated by the choreographed movement of air and blood to the gas exchange surface. The passage of air begins in the upper airways, either via the mouth or nose, and terminates at the alveolar interface, while blood flows from the heart to the alveoli and back again. Computational fluid dynamics (CFD) is a well-established tool for predicting fluid flows and pressure distributions within complex systems. Traditionally CFD has been used to aid in the effective or improved design of a system or device; however, it has become increasingly exploited in biological and medical-based applications further broadening the scope of this computational technique. In this review, we discuss the advancement in application of CFD to the respiratory system and the contributions CFD is currently making toward improving precision medicine. The key areas CFD has been applied to in the pulmonary system are in predicting fluid transport and aerosol distribution within the airways. Here we focus our discussion on fluid flows and in particular on image-based clinically focused CFD in the ventilatory system. We discuss studies spanning from the paranasal sinuses through the conducting airways down to the level of the alveolar airways. The combination of imaging and CFD is enabling improved device design in aerosol transport, improved biomarkers of lung function in clinical trials, and improved predictions and assessment of surgical interventions in the nasal sinuses. WIREs Syst Biol Med 2017, 9:e1392. doi: 10.1002/wsbm.1392 For further resources related to this article, please visit the WIREs website.
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Affiliation(s)
- Kelly S Burrowes
- Department of Chemical and Materials Engineering, University of Auckland, Auckland, New Zealand.,Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | | | - Haribalan Kumar
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
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Colby SM, Kabilan S, Jacob RE, Kuprat AP, Einstein DR, Corley RA. Comparison of realistic and idealized breathing patterns in computational models of airflow and vapor dosimetry in the rodent upper respiratory tract. Inhal Toxicol 2016; 28:192-202. [PMID: 26986954 DOI: 10.3109/08958378.2016.1150367] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
CONTEXT Computational fluid dynamics (CFD) simulations of airflows coupled with physiologically based pharmacokinetic (PBPK) modeling of respiratory tissue doses of airborne materials have traditionally used either steady-state inhalation or a sinusoidal approximation of the breathing cycle for airflow simulations despite their differences from normal breathing patterns. OBJECTIVE Evaluate the impact of realistic breathing patterns, including sniffing, on predicted nasal tissue concentrations of a reactive vapor that targets the nose in rats as a case study. MATERIALS AND METHODS Whole-body plethysmography measurements from a free-breathing rat were used to produce profiles of normal breathing, sniffing and combinations of both as flow inputs to CFD/PBPK simulations of acetaldehyde exposure. RESULTS For the normal measured ventilation profile, modest reductions in time- and tissue depth-dependent areas under the curve (AUC) acetaldehyde concentrations were predicted in the wet squamous, respiratory and transitional epithelium along the main airflow path, while corresponding increases were predicted in the olfactory epithelium, especially the most distal regions of the ethmoid turbinates, versus the idealized profile. The higher amplitude/frequency sniffing profile produced greater AUC increases over the idealized profile in the olfactory epithelium, especially in the posterior region. CONCLUSIONS The differences in tissue AUCs at known lesion-forming regions for acetaldehyde between normal and idealized profiles were minimal, suggesting that sinusoidal profiles may be used for this chemical and exposure concentration. However, depending upon the chemical, exposure system and concentration and the time spent sniffing, the use of realistic breathing profiles, including sniffing, could become an important modulator for local tissue dose predictions.
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Affiliation(s)
- Sean M Colby
- Pacific Northwest National Laboratory, Richland, WA 99354, USA
| | - Senthil Kabilan
- Pacific Northwest National Laboratory, Richland, WA 99354, USA
| | - Richard E Jacob
- Pacific Northwest National Laboratory, Richland, WA 99354, USA
| | - Andrew P Kuprat
- Pacific Northwest National Laboratory, Richland, WA 99354, USA
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29
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Jain R, Kumar H, Tawhai M, Douglas R. The impact of endoscopic sinus surgery on paranasal physiology in simulated sinus cavities. Int Forum Allergy Rhinol 2016; 7:248-255. [PMID: 27869357 DOI: 10.1002/alr.21879] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2016] [Revised: 10/05/2016] [Accepted: 10/18/2016] [Indexed: 01/25/2023]
Abstract
BACKGROUND Surgery improves symptoms for the majority of chronic rhinosinusitis (CRS) patients; however, physiological changes in the sinus cavities remain poorly characterized. Direct measurement of changes in airflow, pressure, temperature, humidity, and intranasal spray distribution following surgery is technically challenging. Accordingly, we have used computational fluid dynamic modeling to quantify how these parameters change postoperatively. METHODS Computed tomography images from a normal control, a patient with CRS preoperatively and postoperatively, and a patient following an endoscopic Lothrop procedure (ELP) were used to create 4 three-dimensional models of the sinus cavities. Changes in physiologic parameters and topical drug distribution were modeled (inhaled air at 16°C and 10% humidity) at the maxillary ostium, frontal recess, and sphenoid ostium. RESULTS Large differences were seen between models. Following surgery, the maxillary ostia were found on average to be cooler (by 2.4°C), with an increased airflow (0.26 m/second; from 0 m/second), and a 9% reduction in absolute humidity. Sphenoid ostial parameters followed a similar trend. Significant changes in frontal recess physiology were seen following ELP in which the recess was 4.2°C cooler, had increased airflow (0.76 m/second) and a 17% reduction in absolute humidity. Topical drug distribution increased with surgery, particularly after ELP. CONCLUSION Surgery changes the geometry and physiology of the paranasal sinuses. These changes are likely to have an impact on wound healing, mucociliary function, and microbial ecology in postoperative cavities. Application of this model to further understand the effects of surgery may help to optimize surgical techniques and improve topical drug delivery.
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Affiliation(s)
- Ravi Jain
- Department of Surgery, The University of Auckland, Auckland, New Zealand
| | - Haribalan Kumar
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
| | - Merryn Tawhai
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
| | - Richard Douglas
- Department of Surgery, The University of Auckland, Auckland, New Zealand
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30
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Miyawaki S, Tawhai MH, Hoffman EA, Wenzel SE, Lin CL. Automatic construction of subject-specific human airway geometry including trifurcations based on a CT-segmented airway skeleton and surface. Biomech Model Mechanobiol 2016; 16:583-596. [PMID: 27704229 DOI: 10.1007/s10237-016-0838-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2016] [Accepted: 09/21/2016] [Indexed: 11/27/2022]
Abstract
We propose a method to construct three-dimensional airway geometric models based on airway skeletons, or centerlines (CLs). Given a CT-segmented airway skeleton and surface, the proposed CL-based method automatically constructs subject-specific models that contain anatomical information regarding branches, include bifurcations and trifurcations, and extend from the trachea to terminal bronchioles. The resulting model can be anatomically realistic with the assistance of an image-based surface; alternatively a model with an idealized skeleton and/or branch diameters is also possible. This method systematically identifies and classifies trifurcations to successfully construct the models, which also provides the number and type of trifurcations for the analysis of the airways from an anatomical point of view. We applied this method to 16 normal and 16 severe asthmatic subjects using their computed tomography images. The average distance between the surface of the model and the image-based surface was 11 % of the average voxel size of the image. The four most frequent locations of trifurcations were the left upper division bronchus, left lower lobar bronchus, right upper lobar bronchus, and right intermediate bronchus. The proposed method automatically constructed accurate subject-specific three-dimensional airway geometric models that contain anatomical information regarding branches using airway skeleton, diameters, and image-based surface geometry. The proposed method can construct (i) geometry automatically for population-based studies, (ii) trifurcations to retain the original airway topology, (iii) geometry that can be used for automatic generation of computational fluid dynamics meshes, and (iv) geometry based only on a skeleton and diameters for idealized branches.
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Affiliation(s)
- Shinjiro Miyawaki
- IIHR-Hydroscience and Engineering, University of Iowa, Iowa City, IA, 52242, USA
- CH2M, 1100 NE Circle Blvd., Suite 300, Corvallis, OR, 97330, USA
| | - Merryn H Tawhai
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Eric A Hoffman
- The Department of Biomedical Engineering, Medicine, and Radiology, University of Iowa, Iowa City, IA, 52242, USA
| | - Sally E Wenzel
- The Division of Pulmonary, Allergy, and Critical Care Medicine, University of Pittsburgh, Pittsburgh, PA, 15213, USA
| | - Ching-Long Lin
- IIHR-Hydroscience and Engineering and the Department of Mechanical and Industrial Engineering, University of Iowa, 3131 Seamans Center, Iowa City, IA, 52242, USA.
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31
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Ibrahim G, Rona A, Hainsworth SV. Modeling the Nonlinear Motion of the Rat Central Airways. J Biomech Eng 2016; 138:2473564. [PMID: 26592166 DOI: 10.1115/1.4032051] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Indexed: 11/08/2022]
Abstract
Advances in volumetric medical imaging techniques allowed the subject-specific modeling of the bronchial flow through the first few generations of the central airways using computational fluid dynamics (CFD). However, a reliable CFD prediction of the bronchial flow requires modeling of the inhomogeneous deformation of the central airways during breathing. This paper addresses this issue by introducing two models of the central airways motion. The first model utilizes a node-to-node mapping between the discretized geometries of the central airways generated from a number of successive computed tomography (CT) images acquired dynamically (without breath hold) over the breathing cycle of two Sprague-Dawley rats. The second model uses a node-to-node mapping between only two discretized airway geometries generated from the CT images acquired at end-exhale and at end-inhale along with the ventilator measurement of the lung volume change. The advantage of this second model is that it uses just one pair of CT images, which more readily complies with the radiation dosage restrictions for humans. Three-dimensional computer aided design geometries of the central airways generated from the dynamic-CT images were used as benchmarks to validate the output from the two models at sampled time-points over the breathing cycle. The central airway geometries deformed by the first model showed good agreement to the benchmark geometries within a tolerance of 4%. The central airway geometry deformed by the second model better approximated the benchmark geometries than previous approaches that used a linear or harmonic motion model.
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32
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Koullapis P, Kassinos S, Bivolarova M, Melikov A. Particle deposition in a realistic geometry of the human conducting airways: Effects of inlet velocity profile, inhalation flowrate and electrostatic charge. J Biomech 2016; 49:2201-2212. [DOI: 10.1016/j.jbiomech.2015.11.029] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2015] [Accepted: 11/11/2015] [Indexed: 10/22/2022]
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Bates JHT. Systems physiology of the airways in health and obstructive pulmonary disease. WILEY INTERDISCIPLINARY REVIEWS-SYSTEMS BIOLOGY AND MEDICINE 2016; 8:423-37. [PMID: 27340818 DOI: 10.1002/wsbm.1347] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Revised: 05/11/2016] [Accepted: 05/12/2016] [Indexed: 01/10/2023]
Abstract
Fresh air entering the mouth and nose is brought to the blood-gas barrier in the lungs by a repetitively branching network of airways. Provided the individual airway branches remain patent, this airway tree achieves an enormous amplification in cross-sectional area from the trachea to the terminal bronchioles. Obstructive lung diseases such as asthma occur when airway patency becomes compromised. Understanding the pathophysiology of these obstructive diseases thus begins with a consideration of the factors that determine the caliber of an individual airway, which include the force balance between the inward elastic recoil of the airway wall, the outward tethering forces of its parenchymal attachments, and any additional forces due to contraction of airway smooth muscle. Other factors may also contribute significantly to airway narrowing, such as thickening of the airway wall and accumulation of secretions in the lumen. Airway obstruction becomes particularly severe when these various factors occur in concert. However, the effect of airway abnormalities on lung function cannot be fully understood only in terms of what happens to a single airway because narrowing throughout the airway tree is invariably heterogeneous and interdependent. Obstructive lung pathologies thus manifest as emergent phenomena arising from the way in which the airway tree behaves a system. These emergent phenomena are studied with clinical measurements of lung function made by spirometry and by mechanical impedance measured with the forced oscillation technique. Anatomically based computational models are linking these measurements to underlying anatomic structure in systems physiology terms. WIREs Syst Biol Med 2016, 8:423-437. doi: 10.1002/wsbm.1347 For further resources related to this article, please visit the WIREs website.
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Affiliation(s)
- Jason H T Bates
- Department of Medicine, University of Vermont College of Medicine, Burlington, VT, USA
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34
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Raghavan D, Jain R. Increasing awareness of sex differences in airway diseases. Respirology 2015; 21:449-59. [PMID: 26677803 DOI: 10.1111/resp.12702] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Revised: 07/21/2015] [Accepted: 08/10/2015] [Indexed: 12/15/2022]
Abstract
There is growing epidemiologic data demonstrating sex differences with respect to prevalence and progression of airway diseases, including asthma, chronic obstructive pulmonary disease (COPD), cystic fibrosis (CF) and non-CF-related bronchiectasis. In asthma, for example, young boys have increased exacerbations and higher morbidity than girls which distinctly reverses after adolescence and into adulthood. In COPD, a disease that was historically considered an illness of men, the number of women dying per year is now greater than in men. Finally, women with CF-related bronchiectasis have a decreased median life expectancy relative to men and a higher risk of respiratory infections despite equal prevalence of the disease. A number of studies now exist demonstrating mechanisms behind these sex differences, including influences of genetic predisposition, sex hormones and comorbidities. The notable sex disparity has potential diagnostic, therapeutic and prognostic implications and for the practicing respiratory or general physician, a familiarity with these distinctions may augment effective management of patients with airway diseases. This review seeks to concisely summarize the data regarding gender-based differences in airway diseases, outline the current understanding of contributing factors and discuss therapeutic implications for clinicians.
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Affiliation(s)
- Deepa Raghavan
- Division of Pulmonary and Critical Care, Department of Medicine, University of Arkansas Medical Sciences, Little Rock, Arkansas, USA
| | - Raksha Jain
- Division of Pulmonary and Critical Care, Department of Medicine, University of Texas Southwestern, Dallas, Texas, USA
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35
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Jahani N, Choi S, Choi J, Iyer K, Hoffman EA, Lin CL. Assessment of regional ventilation and deformation using 4D-CT imaging for healthy human lungs during tidal breathing. J Appl Physiol (1985) 2015; 119:1064-74. [PMID: 26316512 DOI: 10.1152/japplphysiol.00339.2015] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2015] [Accepted: 08/20/2015] [Indexed: 11/22/2022] Open
Abstract
This study aims to assess regional ventilation, nonlinearity, and hysteresis of human lungs during dynamic breathing via image registration of four-dimensional computed tomography (4D-CT) scans. Six healthy adult humans were studied by spiral multidetector-row CT during controlled tidal breathing as well as during total lung capacity and functional residual capacity breath holds. Static images were utilized to contrast static vs. dynamic (deep vs. tidal) breathing. A rolling-seal piston system was employed to maintain consistent tidal breathing during 4D-CT spiral image acquisition, providing required between-breath consistency for physiologically meaningful reconstructed respiratory motion. Registration-derived variables including local air volume and anisotropic deformation index (ADI, an indicator of preferential deformation in response to local force) were employed to assess regional ventilation and lung deformation. Lobar distributions of air volume change during tidal breathing were correlated with those of deep breathing (R(2) ≈ 0.84). Small discrepancies between tidal and deep breathing were shown to be likely due to different distributions of air volume change in the left and the right lungs. We also demonstrated an asymmetric characteristic of flow rate between inhalation and exhalation. With ADI, we were able to quantify nonlinearity and hysteresis of lung deformation that can only be captured in dynamic images. Nonlinearity quantified by ADI is greater during inhalation, and it is stronger in the lower lobes (P < 0.05). Lung hysteresis estimated by the difference of ADI between inhalation and exhalation is more significant in the right lungs than that in the left lungs.
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Affiliation(s)
- Nariman Jahani
- Department of Mechanical and Industrial Engineering, The University of Iowa, Iowa City, Iowa; IIHR-Hydroscience and Engineering, The University of Iowa, Iowa City, Iowa
| | - Sanghun Choi
- Department of Mechanical and Industrial Engineering, The University of Iowa, Iowa City, Iowa; IIHR-Hydroscience and Engineering, The University of Iowa, Iowa City, Iowa
| | - Jiwoong Choi
- Department of Mechanical and Industrial Engineering, The University of Iowa, Iowa City, Iowa; IIHR-Hydroscience and Engineering, The University of Iowa, Iowa City, Iowa
| | - Krishna Iyer
- Department of Biomedical Engineering, The University of Iowa, Iowa City, Iowa
| | - Eric A Hoffman
- Department of Biomedical Engineering, The University of Iowa, Iowa City, Iowa; Department of Internal Medicine, The University of Iowa, Iowa City, Iowa; Department of Radiology, The University of Iowa, Iowa City, Iowa
| | - Ching-Long Lin
- Department of Mechanical and Industrial Engineering, The University of Iowa, Iowa City, Iowa; IIHR-Hydroscience and Engineering, The University of Iowa, Iowa City, Iowa;
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Wu D, Miyawaki S, Tawhai MH, Hoffman EA, Lin CL. A Numerical Study of Water Loss Rate Distributions in MDCT-Based Human Airway Models. Ann Biomed Eng 2015; 43:2708-21. [PMID: 25869455 DOI: 10.1007/s10439-015-1318-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2014] [Accepted: 04/03/2015] [Indexed: 01/06/2023]
Abstract
Both three-dimensional (3D) and one-dimensional (1D) computational fluid dynamics methods are applied to study regional water loss in three multi-detector row computed-tomography-based human airway models at the minute ventilations of 6, 15 and 30 L/min. The overall water losses predicted by both 3D and 1D models in the entire respiratory tract agree with available experimental measurements. However, 3D and 1D models reveal different regional water loss rate distributions due to the 3D secondary flows formed at bifurcations. The secondary flows cause local skewed temperature and humidity distributions on inspiration acting to elevate the local water loss rate; and the secondary flow at the carina tends to distribute more cold air to the lower lobes. As a result, the 3D model predicts that the water loss rate first increases with increasing airway generation, and then decreases as the air approaches saturation, while the 1D model predicts a monotonic decrease of water loss rate with increasing airway generation. Moreover, the 3D (or 1D) model predicts relatively higher water loss rates in lower (or upper) lobes. The regional water loss rate can be related to the non-dimensional wall shear stress (τ (*)) by the non-dimensional mass transfer coefficient (h 0 (*) ) as [Formula: see text].
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Affiliation(s)
- Dan Wu
- Department of Mechanical and Industrial Engineering, 2406 Seamans Center for the Engineering Arts and Sciences, The University of Iowa, Iowa City, 52242, Iowa, USA.,Department of IIHR-Hydroscience & Engineering, The University of Iowa, Iowa City, 52242, Iowa, USA
| | - Shinjiro Miyawaki
- Department of IIHR-Hydroscience & Engineering, The University of Iowa, Iowa City, 52242, Iowa, USA
| | - Merryn H Tawhai
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
| | - Eric A Hoffman
- Department of Biomedical Engineering, The University of Iowa, Iowa City, 52242, Iowa, USA.,Department of Internal Medicine, The University of Iowa, Iowa City, 52242, Iowa, USA.,Department of Radiology, The University of Iowa, Iowa City, 52242, Iowa, USA
| | - Ching-Long Lin
- Department of Mechanical and Industrial Engineering, 2406 Seamans Center for the Engineering Arts and Sciences, The University of Iowa, Iowa City, 52242, Iowa, USA. .,Department of IIHR-Hydroscience & Engineering, The University of Iowa, Iowa City, 52242, Iowa, USA.
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Smith BM, Hoffman EA, Barr RG. Author's response: Airway anatomy in COPD: many dimensions to consider. Thorax 2015; 70:585. [PMID: 25572599 DOI: 10.1136/thoraxjnl-2014-206606] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Accepted: 11/24/2014] [Indexed: 11/03/2022]
Affiliation(s)
- Benjamin M Smith
- Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, New York, USA Department of Medicine, McGill University, Montreal, Canada
| | - Eric A Hoffman
- Departments of Radiology, Medicine and Biomedical Engineering, University of Iowa, Iowa City, Iowa, USA
| | - R Graham Barr
- Department of Medicine, College of Physicians and Surgeons, Columbia University, New York, New York, USA Department of Epidemiology, Mailman School of Public Health, Columbia University, New York, New York, USA
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Cilfone NA, Ford CB, Marino S, Mattila JT, Gideon HP, Flynn JL, Kirschner DE, Linderman JJ. Computational modeling predicts IL-10 control of lesion sterilization by balancing early host immunity-mediated antimicrobial responses with caseation during mycobacterium tuberculosis infection. THE JOURNAL OF IMMUNOLOGY 2014; 194:664-77. [PMID: 25512604 DOI: 10.4049/jimmunol.1400734] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Although almost a third of the world's population is infected with the bacterial pathogen Mycobacterium tuberculosis, our understanding of the functions of many immune factors involved in fighting infection is limited. Determining the role of the immunosuppressive cytokine IL-10 at the level of the granuloma has proven difficult because of lesional heterogeneity and the limitations of animal models. In this study, we take an in silico approach and, through a series of virtual experiments, we predict several novel roles for IL-10 in tuberculosis granulomas: 1) decreased levels of IL-10 lead to increased numbers of sterile lesions, but at the cost of early increased caseation; 2) small increases in early antimicrobial activity cause this increased lesion sterility; 3) IL-10 produced by activated macrophages is a major mediator of early antimicrobial activity and early host-induced caseation; and 4) increasing levels of infected macrophage derived IL-10 promotes bacterial persistence by limiting the early antimicrobial response and preventing lesion sterilization. Our findings, currently only accessible using an in silico approach, suggest that IL-10 at the individual granuloma scale is a critical regulator of lesion outcome. These predictions suggest IL-10-related mechanisms that could be used as adjunctive therapies during tuberculosis.
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Affiliation(s)
- Nicholas A Cilfone
- Department of Chemical Engineering, University of Michigan, Ann Arbor, MI 48109
| | | | - Simeone Marino
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI 48109; and
| | - Joshua T Mattila
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, PA 15219
| | - Hannah P Gideon
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, PA 15219
| | - JoAnne L Flynn
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, PA 15219
| | - Denise E Kirschner
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI 48109; and
| | - Jennifer J Linderman
- Department of Chemical Engineering, University of Michigan, Ann Arbor, MI 48109;
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Burrowes KS, Doel T, Brightling C. Computational modeling of the obstructive lung diseases asthma and COPD. J Transl Med 2014; 12 Suppl 2:S5. [PMID: 25471125 PMCID: PMC4255909 DOI: 10.1186/1479-5876-12-s2-s5] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Asthma and chronic obstructive pulmonary disease (COPD) are characterized by airway obstruction and airflow limitation and pose a huge burden to society. These obstructive lung diseases impact the lung physiology across multiple biological scales. Environmental stimuli are introduced via inhalation at the organ scale, and consequently impact upon the tissue, cellular and sub-cellular scale by triggering signaling pathways. These changes are propagated upwards to the organ level again and vice versa. In order to understand the pathophysiology behind these diseases we need to integrate and understand changes occurring across these scales and this is the driving force for multiscale computational modeling. There is an urgent need for improved diagnosis and assessment of obstructive lung diseases. Standard clinical measures are based on global function tests which ignore the highly heterogeneous regional changes that are characteristic of obstructive lung disease pathophysiology. Advances in scanning technology such as hyperpolarized gas MRI has led to new regional measurements of ventilation, perfusion and gas diffusion in the lungs, while new image processing techniques allow these measures to be combined with information from structural imaging such as Computed Tomography (CT). However, it is not yet known how to derive clinical measures for obstructive diseases from this wealth of new data. Computational modeling offers a powerful approach for investigating this relationship between imaging measurements and disease severity, and understanding the effects of different disease subtypes, which is key to developing improved diagnostic methods. Gaining an understanding of a system as complex as the respiratory system is difficult if not impossible via experimental methods alone. Computational models offer a complementary method to unravel the structure-function relationships occurring within a multiscale, multiphysics system such as this. Here we review the current state-of-the-art in techniques developed for pulmonary image analysis, development of structural models of the respiratory system and predictions of function within these models. We discuss application of modeling techniques to obstructive lung diseases, namely asthma and emphysema and the use of models to predict response to therapy. Finally we introduce a large European project, AirPROM that is developing multiscale models to investigate structure-function relationships in asthma and COPD.
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Abstract
PURPOSE OF REVIEW The purpose of this review is to discuss the present systems biology approach to asthma and how it is helping to define asthma subtypes. Although the general concept of systems biology will be discussed, the article will focus on recent developments in the field related to asthma. RECENT FINDINGS The most recent work in systems biology and asthma has occurred in the area of genomics (e.g., pharmacogenomics and gene-environment interactions), protein interaction networks [e.g., interleukin (IL)-33/IL-1 receptor-like 1 signaling], cluster analysis of asthma patients (e.g., application of severe asthma research program clusters to a general urban asthma population), and multiscale approaches to asthma encompassing data from the molecule to whole organ (e.g., modeling of airways hyperresponsiveness). SUMMARY The results of recent work in this area have led to new insight into gene-cytokine and protein-protein networks involved in asthma, a better determination of key clinical factors associated with asthma subtypes, and the beginning of sophisticated multiscale approaches to modeling, understanding and predicting the behavior of the asthmatic lung.
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Wu D, Tawhai MH, Hoffman EA, Lin CL. A numerical study of heat and water vapor transfer in MDCT-based human airway models. Ann Biomed Eng 2014; 42:2117-31. [PMID: 25081386 DOI: 10.1007/s10439-014-1074-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Accepted: 07/17/2014] [Indexed: 01/05/2023]
Abstract
A three-dimensional (3D) thermo-fluid model is developed to study regional distributions of temperature and water vapor in three multi-detector row computed-tomography-based human airways with minute ventilations of 6, 15 and 30 L/min. A one-dimensional (1D) model is also solved to provide necessary initial and boundary conditions for the 3D model. Both 3D and 1D predicted temperature distributions agree well with available in vivo measurement data. On inspiration, the 3D cold high-speed air stream is split at the bifurcation to form secondary flows, with its cold regions biased toward the inner wall. The cold air flowing along the wall is warmed up more rapidly than the air in the lumen center. The repeated splitting pattern of air streams caused by bifurcations acts as an effective mechanism for rapid heat and mass transfer in 3D. This provides a key difference from the 1D model, where heating relies largely on diffusion in the radial direction, thus significantly affecting gradient-dependent variables, such as energy flux and water loss rate. We then propose the correlations for respective heat and mass transfer in the airways of up to 6 generations: [Formula: see text] and [Formula: see text], where Nu is the Nusselt number, Sh is the Sherwood number, Re is the branch Reynolds number, D a is the airway equivalent diameter, and [Formula: see text] is the tracheal equivalent diameter.
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Affiliation(s)
- Dan Wu
- Department of Mechanical and Industrial Engineering, The University of Iowa, Iowa City, IA, 52242, USA
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Bhatt SP, Sieren JC, Newell JD, Comellas AP, Hoffman EA. Disproportionate contribution of right middle lobe to emphysema and gas trapping on computed tomography. PLoS One 2014; 9:e102807. [PMID: 25054539 PMCID: PMC4108372 DOI: 10.1371/journal.pone.0102807] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2014] [Accepted: 06/24/2014] [Indexed: 11/18/2022] Open
Abstract
RATIONALE Given that the diagnosis of chronic obstructive pulmonary disease (COPD) relies on demonstrating airflow limitation by spirometry, which is known to be poorly sensitive to early disease, and to regional differences in emphysema, we sought to evaluate individual lobar contributions to global spirometric measures. METHODS Subjects with COPD were compared with smokers without airflow obstruction, and non-smokers. Emphysema (% low attenuation area, LAAinsp<-950 HU, at end-inspiration) and gas trapping (%LAAexp<-856 HU at end-expiration) on CT were quantified using density mask analyses for the whole lung and for individual lobes, and distribution across lobes and strength of correlation with spirometry were compared. RESULTS The right middle lobe had the highest %LAAinsp<-950 HU in smokers and controls, and the highest %LAAexp<-856 HU in all three groups. While RML contributed to emphysema and gas trapping disproportionately to its relatively small size, it also showed the least correlation with spirometry. There was no change in correlation of whole lung CT metrics with spirometry when the middle lobe was excluded from analyses. Similarly, RML had the highest %LAAexp<-856 HU while having the least correlation with spirometry. CONCLUSIONS Because of the right middle lobe's disproportionate contribution to CT-based emphysema measurements, and low contribution to spirometry, longitudinal studies of emphysema progression may benefit from independent analysis of the middle lobe in whole lung quantitative CT assessments. Our findings may also have implications for heterogeneity assessments and target lobe selection for lung volume reduction. CLINICAL TRIAL REGISTRATION ClinicalTrials.gov NCT00608764.
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Affiliation(s)
- Surya P. Bhatt
- Division of Pulmonary and Critical Care Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Jessica C. Sieren
- Departments of Radiology and Biomedical Engineering, University of Iowa, Iowa City, Iowa, United States of America
| | - John D. Newell
- Departments of Radiology and Biomedical Engineering, University of Iowa, Iowa City, Iowa, United States of America
| | - Alejandro P. Comellas
- Division of Pulmonary and Critical Care Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Eric A. Hoffman
- Departments of Radiology and Biomedical Engineering, University of Iowa, Iowa City, Iowa, United States of America
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Ijaz T, Pazdrak K, Kalita M, Konig R, Choudhary S, Tian B, Boldogh I, Brasier AR. Systems biology approaches to understanding Epithelial Mesenchymal Transition (EMT) in mucosal remodeling and signaling in asthma. World Allergy Organ J 2014; 7:13. [PMID: 24982697 PMCID: PMC4068075 DOI: 10.1186/1939-4551-7-13] [Citation(s) in RCA: 84] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2013] [Accepted: 05/16/2014] [Indexed: 11/10/2022] Open
Abstract
A pathological hallmark of asthma is chronic injury and repair, producing dysfunction of the epithelial barrier function. In this setting, increased oxidative stress, growth factor- and cytokine stimulation, together with extracellular matrix contact produces transcriptional reprogramming of the epithelial cell. This process results in epithelial-mesenchymal transition (EMT), a cellular state associated with loss of epithelial polarity, expression of mesenchymal markers, enhanced mobility and extracellular matrix remodeling. As a result, the cellular biology of the EMT state produces characteristic changes seen in severe, refractory asthma: myofibroblast expansion, epithelial trans-differentiation and subepithelial fibrosis. EMT also induces profound changes in epithelial responsiveness that affects innate immune signaling that may have impact on the adaptive immune response and effectiveness of glucocorticoid therapy in severe asthma. We discuss how this complex phenotype is beginning to be understood using systems biology-level approaches through perturbations coupled with high throughput profiling and computational modeling. Understanding the distinct changes induced by EMT at the systems level may provide translational strategies to reverse the altered signaling and physiology of refractory asthma.
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Affiliation(s)
- Talha Ijaz
- Department of Biochemistry and Molecular Biology, The University of Texas Medical Branch, 301 University Blvd, Galveston 77555-1060, Texas, USA
| | - Konrad Pazdrak
- Department of Biochemistry and Molecular Biology, The University of Texas Medical Branch, 301 University Blvd, Galveston 77555-1060, Texas, USA.,Sealy Center for Molecular Medicine, The University of Texas Medical Branch, 301 University Blvd, Galveston 77555-1060, Texas, USA.,Institute for Translational Sciences, The University of Texas Medical Branch, 301 University Blvd, Galveston 77555-1060, Texas, USA
| | - Mridul Kalita
- Sealy Center for Molecular Medicine, The University of Texas Medical Branch, 301 University Blvd, Galveston 77555-1060, Texas, USA.,Department of Internal Medicine, The University of Texas Medical Branch, 301 University Blvd, Galveston 77555-1060, Texas, USA
| | - Rolf Konig
- Sealy Center for Molecular Medicine, The University of Texas Medical Branch, 301 University Blvd, Galveston 77555-1060, Texas, USA.,Department of Microbiology and Immunology, The University of Texas Medical Branch, 301 University Blvd, Galveston 77555-1060, Texas, USA
| | - Sanjeev Choudhary
- Department of Biochemistry and Molecular Biology, The University of Texas Medical Branch, 301 University Blvd, Galveston 77555-1060, Texas, USA.,Sealy Center for Molecular Medicine, The University of Texas Medical Branch, 301 University Blvd, Galveston 77555-1060, Texas, USA.,Department of Microbiology and Immunology, The University of Texas Medical Branch, 301 University Blvd, Galveston 77555-1060, Texas, USA
| | - Bing Tian
- Department of Internal Medicine, The University of Texas Medical Branch, 301 University Blvd, Galveston 77555-1060, Texas, USA
| | - Istvan Boldogh
- Department of Biochemistry and Molecular Biology, The University of Texas Medical Branch, 301 University Blvd, Galveston 77555-1060, Texas, USA.,Sealy Center for Molecular Medicine, The University of Texas Medical Branch, 301 University Blvd, Galveston 77555-1060, Texas, USA.,Department of Microbiology and Immunology, The University of Texas Medical Branch, 301 University Blvd, Galveston 77555-1060, Texas, USA
| | - Allan R Brasier
- Sealy Center for Molecular Medicine, The University of Texas Medical Branch, 301 University Blvd, Galveston 77555-1060, Texas, USA.,Institute for Translational Sciences, The University of Texas Medical Branch, 301 University Blvd, Galveston 77555-1060, Texas, USA.,Department of Internal Medicine, The University of Texas Medical Branch, 301 University Blvd, Galveston 77555-1060, Texas, USA
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Jahani N, Yin Y, Hoffman EA, Lin CL. Assessment of regional non-linear tissue deformation and air volume change of human lungs via image registration. J Biomech 2014; 47:1626-33. [PMID: 24685127 DOI: 10.1016/j.jbiomech.2014.02.040] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Revised: 02/27/2014] [Accepted: 02/27/2014] [Indexed: 01/06/2023]
Abstract
We evaluate the non-linear characteristics of the human lung via image registration-derived local variables based on volumetric multi-detector-row computed tomographic (MDCT) lung image data of six normal human subjects acquired at three inflation levels: 20% of vital capacity (VC), 60% VC and 80% VC. Local variables include Jacobian (ratio of volume change) and maximum shear strain for assessment of lung deformation, and air volume change for assessment of air distribution. First, the variables linearly interpolated between 20% and 80% VC images to reflect deformation from 20% to 60% VC are compared with those of direct registration of 20% and 60% VC images. The result shows that the linearly-interpolated variables agree only qualitatively with those of registration (P<0.05). Then, a quadratic (or linear) interpolation is introduced to link local variables to global air volumes of three images (or 20% and 80% VC images). A sinusoidal breathing waveform is assumed for assessing the time rate of change of these variables. The results show significant differences between two-image and three-image results (P<0.05). The three-image results for the whole lung indicate that the peak of the maximum shear rate occurs at about 37% of the maximum volume difference between 20% and 80% VC, while the peaks for the Jacobian and flow rate occur at 50%. This is in agreement with accepted physiology whereby lung tissues deform more at lower lung volumes due to lower elasticity and greater compliance. Furthermore, the three-image results show that the upper and middle lobes, even in the recumbent, supine posture, reach full expansion earlier than the lower lobes.
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Affiliation(s)
- Nariman Jahani
- Department of Mechanical and Industrial Engineering, The University of Iowa, Iowa City, IA 52242, USA; Department of IIHR-Hydroscience & Engineering, The University of Iowa, Iowa City, IA 52242, USA
| | - Youbing Yin
- Department of Mechanical and Industrial Engineering, The University of Iowa, Iowa City, IA 52242, USA
| | - Eric A Hoffman
- Department of Biomedical Engineering, The University of Iowa, Iowa City, IA 52242, USA; Department of Internal Medicine, The University of Iowa, Iowa City, IA 52242, USA; Department of Radiology, The University of Iowa, Iowa City, IA 52242, USA
| | - Ching-Long Lin
- Department of Mechanical and Industrial Engineering, The University of Iowa, Iowa City, IA 52242, USA; Department of IIHR-Hydroscience & Engineering, The University of Iowa, Iowa City, IA 52242, USA.
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