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Gill R, Boucher M, Henry C, Bossé Y. A Quick Method to Assess Airway Distensibility in Mice. Ann Biomed Eng 2024; 52:2193-2202. [PMID: 38619723 PMCID: PMC11247055 DOI: 10.1007/s10439-024-03518-9] [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: 12/21/2023] [Accepted: 04/11/2024] [Indexed: 04/16/2024]
Abstract
Airway distensibility is defined as the ease whereby airways are dilating in response to inflating lung pressure. If measured swiftly and accurately, airway distensibility would be a useful readout to parse the various elements contributing to airway wall stiffening, such as smooth muscle contraction, surface tension, and airway remodeling. The goal of the present study was to develop a method for measuring airway distensibility in mice. Lungs of BALB/c and C57BL/6 mice from either sex were subjected to stepwise changes in pressure. At each pressure step, an oscillometric perturbation was used to measure the impedance spectrum, on which the constant-phase model was fitted to deduce a surrogate for airway caliber called Newtonian conductance (GN). The change in GN over the change in pressure was subsequently used as an index of airway distensibility. An additional group of mice was infused with methacholine to confirm that smooth muscle contraction changes airway distensibility. GN increased with increasing steps in pressure, suggesting that the extent to which this occurs can be used as an index of airway distensibility. Airway distensibility was greater in BALB/c than C57BL/6 mice, and its variation by sex was mouse strain dependent, being greater in female than male in BALB/c mice with an inverse trend in C57BL/6 mice. Airway distensibility was also decreased by methacholine. This novel method swiftly measures airway distensibility in mice. Airway distensibility was also shown to vary with sex and mouse strain and to be sensitive to the contraction of smooth muscle.
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Affiliation(s)
- Rebecka Gill
- Institut Universitaire de Cardiologie et de Pneumologie de Québec (IUCPQ)-Université Laval, 2725, Chemin Sainte-Foy, Quebec, QC, G1V 4G5, Canada
| | - Magali Boucher
- Institut Universitaire de Cardiologie et de Pneumologie de Québec (IUCPQ)-Université Laval, 2725, Chemin Sainte-Foy, Quebec, QC, G1V 4G5, Canada
| | - Cyndi Henry
- Institut Universitaire de Cardiologie et de Pneumologie de Québec (IUCPQ)-Université Laval, 2725, Chemin Sainte-Foy, Quebec, QC, G1V 4G5, Canada
| | - Ynuk Bossé
- Institut Universitaire de Cardiologie et de Pneumologie de Québec (IUCPQ)-Université Laval, 2725, Chemin Sainte-Foy, Quebec, QC, G1V 4G5, Canada.
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Bossé Y. Understanding the fundamentals of oscillometry from a strip of lung tissue. Front Physiol 2022; 13:978332. [PMID: 36203932 PMCID: PMC9530782 DOI: 10.3389/fphys.2022.978332] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2022] [Accepted: 09/08/2022] [Indexed: 11/19/2022] Open
Abstract
Metrics used in spirometry caught on in respiratory medicine not only because they provide information of clinical importance but also because of a keen understanding of what is being measured. The forced expiratory volume in 1 s (FEV1), for example, is the maximal volume of air that can be expelled during the first second of a forced expiratory maneuver starting from a lung inflated to total lung capacity (TLC). Although it represents a very gross measurement of lung function, it is now used to guide the diagnosis and management of many lung disorders. Metrics used in oscillometry are not as concrete. Resistance, for example, has several connotations and its proper meaning in the context of a lung probed by an external device is not always intuitive. I think that the popularization of oscillometry and its firm implementation in respiratory guidelines starts with a keen understanding of what exactly is being measured. This review is an attempt to clearly explain the basic metrics of oscillometry. In my opinion, the fundamentals of oscillometry can be understood using a simple example of an excised strip of lung tissue subjected to a sinusoidal strain. The key notion is to divide the sinusoidal reacting force from the tissue strip into two sinusoids, one in phase with the strain and one preceding the strain by exactly a quarter of a cycle. Similar notions can then be applied to a whole lung subjected to a sinusoidal flow imposed at the mouth by an external device to understand basic metrics of oscillometry, including resistance, elastance, impedance, inertance, reactance and resonant frequency.
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Robichaud A, Fereydoonzad L, Collins SL, Loube JM, Ishii Y, Horton MR, Martin JG, Mitzner W. Airway compliance measurements in mouse models of respiratory diseases. Am J Physiol Lung Cell Mol Physiol 2021; 321:L204-L212. [PMID: 34009049 DOI: 10.1152/ajplung.00470.2020] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
The quantification of airway compliance (Caw) is essential to the study of airway alterations in disease models. However, the required measurements of airway pressure and volume are difficult to acquire in mice. We hypothesized that the inflation limb of full-range pressure-volume (PV) curves could be used to quantify Caw, as it contains a segment where only the airway tree is distended. The study objective was to assess the feasibility of the approach by analysis of full-range PV curves previously collected in three mouse models: an elastase model of emphysema, a genetic model spontaneously developing emphysema (leukotriene C4 synthase knockout; LTC4S-KO), and a bleomycin model of lung fibrosis. Attempts to validate results included Caw change relative to respiratory system compliance (ΔCaw/ΔC), the minute work of breathing (mWOB), and the elastance at 20.5 Hz (Ers_20.5) from prior respiratory mechanics measurements in the same subjects. Caw was estimated at 3% of total compliance in healthy mice or 2.3 ± 1 μL/cmH2O (n = 17). The technique detected changes in models of respiratory obstructive and restrictive diseases relative to control mice as well as differences in the two emphysema models studied. The changes in Caw were consistent with those seen in ΔCaw/ΔC, mWOB, or Ers_20.5, with some variations according to the model, as well as with results reported in the literature in humans and mice. Direct Caw measurements in subjects as small as mice could prove useful to further characterize other respiratory disease models associated with airway remodeling or to assess treatment effects.
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Affiliation(s)
| | | | - Samuel L Collins
- Johns Hopkins University School of Medicine, Johns Hopkins University, Baltimore, Maryland
| | - Jeffrey Martin Loube
- Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland
| | - Yumiko Ishii
- Meakins-Christie Laboratories, Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada
| | - Maureen R Horton
- Johns Hopkins University School of Medicine, Johns Hopkins University, Baltimore, Maryland
| | - James G Martin
- Meakins-Christie Laboratories, Research Institute of the McGill University Health Centre, Montreal, Quebec, Canada
| | - Wayne Mitzner
- Johns Hopkins Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland
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Bossé Y. The Strain on Airway Smooth Muscle During a Deep Inspiration to Total Lung Capacity. JOURNAL OF ENGINEERING AND SCIENCE IN MEDICAL DIAGNOSTICS AND THERAPY 2019; 2:0108021-1080221. [PMID: 32328568 PMCID: PMC7164505 DOI: 10.1115/1.4042309] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 11/06/2018] [Indexed: 02/05/2023]
Abstract
The deep inspiration (DI) maneuver entices a great deal of interest because of its ability to temporarily ease the flow of air into the lungs. This salutary effect of a DI is proposed to be mediated, at least partially, by momentarily increasing the operating length of airway smooth muscle (ASM). Concerningly, this premise is largely derived from a growing body of in vitro studies investigating the effect of stretching ASM by different magnitudes on its contractility. The relevance of these in vitro findings remains uncertain, as the real range of strains ASM undergoes in vivo during a DI is somewhat elusive. In order to understand the regulation of ASM contractility by a DI and to infer on its putative contribution to the bronchodilator effect of a DI, it is imperative that in vitro studies incorporate levels of strains that are physiologically relevant. This review summarizes the methods that may be used in vivo in humans to estimate the strain experienced by ASM during a DI from functional residual capacity (FRC) to total lung capacity (TLC). The strengths and limitations of each method, as well as the potential confounders, are also discussed. A rough estimated range of ASM strains is provided for the purpose of guiding future in vitro studies that aim at quantifying the regulatory effect of DI on ASM contractility. However, it is emphasized that, owing to the many limitations and confounders, more studies will be needed to reach conclusive statements.
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Affiliation(s)
- Ynuk Bossé
- Université Laval, Faculty of Medicine, Department of Medicine, IUCPQ, M2694, Pavillon Mallet, Chemin Sainte-Foy, Québec, QC G1V 4G5, Canada e-mail:
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Port J, Tao Z, Junger A, Joppek C, Tempel P, Husemann K, Singer F, Latzin P, Yammine S, Nagel JH, Kohlhäufl M. A simple method to reconstruct the molar mass signal of respiratory gas to assess small airways with a double-tracer gas single-breath washout. Med Biol Eng Comput 2017; 55:1975-1987. [PMID: 28357624 DOI: 10.1007/s11517-017-1633-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Accepted: 03/13/2017] [Indexed: 01/13/2023]
Abstract
For the assessment of small airway diseases, a noninvasive double-tracer gas single-breath washout (DTG-SBW) with sulfur hexafluoride (SF6) and helium (He) as tracer components has been proposed. It is assumed that small airway diseases may produce typical ventilation inhomogeneities which can be detected within one single tidal breath, when using two tracer components. Characteristic parameters calculated from a relative molar mass (MM) signal of the airflow during the washout expiration phase are analyzed. The DTG-SBW signal is acquired by subtracting a reconstructed MM signal without tracer gas from the signal measured with an ultrasonic sensor during in- and exhalation of the double-tracer gas for one tidal breath. In this paper, a simple method to determine the reconstructed MM signal is presented. Measurements on subjects with and without obstructive lung diseases including the small airways have shown high reliability and reproducibility of this method.
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Affiliation(s)
- Johannes Port
- Institut für Biomedizinische Technik, Universität Stuttgart, Stuttgart, Germany.
| | - Ziran Tao
- Institut für Biomedizinische Technik, Universität Stuttgart, Stuttgart, Germany
| | - Annika Junger
- Institut für Biomedizinische Technik, Universität Stuttgart, Stuttgart, Germany
| | - Christoph Joppek
- Institut für Biomedizinische Technik, Universität Stuttgart, Stuttgart, Germany
| | - Philipp Tempel
- Institut für Biomedizinische Technik, Universität Stuttgart, Stuttgart, Germany
| | - Kim Husemann
- Klinik Schillerhöhe, Zentrum für Pneumologie und Thoraxchirurgie, Robert-Bosch-Hospital, Gerlingen, Germany.,Internistische Facharztpraxis für Pneumologie, Allergologie, Thoraxonkologie, Bronchoskopie und Schlafmedizin, MVZ Klinikum Kempten GmbH, Kempten, Germany
| | - Florian Singer
- University Children's Hospital Zurich, Zurich, Switzerland
| | - Philipp Latzin
- University Children's Hospital Basel, Basel, Switzerland
| | - Sophie Yammine
- University Children's Hospital Basel, Basel, Switzerland
| | - Joachim H Nagel
- Institut für Biomedizinische Technik, Universität Stuttgart, Stuttgart, Germany
| | - Martin Kohlhäufl
- Klinik Schillerhöhe, Zentrum für Pneumologie und Thoraxchirurgie, Robert-Bosch-Hospital, Gerlingen, Germany
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Gazzola M, Lortie K, Henry C, Mailhot-Larouche S, Chapman DG, Couture C, Seow CY, Paré PD, King GG, Boulet LP, Bossé Y. Airway smooth muscle tone increases airway responsiveness in healthy young adults. Am J Physiol Lung Cell Mol Physiol 2016; 312:L348-L357. [PMID: 27941076 DOI: 10.1152/ajplung.00400.2016] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Revised: 12/06/2016] [Accepted: 12/07/2016] [Indexed: 11/22/2022] Open
Abstract
Force adaptation, a process whereby sustained spasmogenic activation (viz., tone) of airway smooth muscle (ASM) increases its contractile capacity, has been reported in isolated ASM tissues in vitro, as well as in mice in vivo. The objective of the present study was to assess the effect of tone on airway responsiveness in humans. Ten healthy volunteers underwent methacholine challenge on two occasions. One challenge consisted of six serial doses of saline followed by a single high dose of methacholine. The other consisted of six low doses of methacholine 5 min apart followed by a higher dose. The cumulative dose was identical for both challenges. After both methacholine challenges, subjects took a deep inspiration (DI) to total lung capacity as another way to probe ASM mechanics. Responses to methacholine and the DI were measured using a multifrequency forced oscillation technique. Compared with a single high dose, the challenge preceded by tone led to an elevated response measured by respiratory system resistance (Rrs) and reactance at 5 Hz. However, there was no difference in the increase in Rrs at 19 Hz, suggesting a predominant effect on smaller airways. Increased tone also reduced the efficacy of DI, measured by an attenuated maximal dilation during the DI and an increased renarrowing post-DI. We conclude that ASM tone increases small airway responsiveness to inhaled methacholine and reduces the effectiveness of DI in healthy humans. This suggests that force adaptation may contribute to airway hyperresponsiveness and the reduced bronchodilatory effect of DI in asthma.
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Affiliation(s)
- Morgan Gazzola
- Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec, Québec, Canada
| | - Katherine Lortie
- Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec, Québec, Canada
| | - Cyndi Henry
- Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec, Québec, Canada
| | - Samuel Mailhot-Larouche
- Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec, Québec, Canada
| | - David G Chapman
- Vermont Lung Center, University of Vermont College of Medicine, Burlington, Vermont
| | - Christian Couture
- Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec, Québec, Canada
| | - Chun Y Seow
- University of British Columbia Centre for Heart Lung Innovation, St. Paul's Hospital, Vancouver, British Columbia, Canada
| | - Peter D Paré
- University of British Columbia Centre for Heart Lung Innovation, St. Paul's Hospital, Vancouver, British Columbia, Canada
| | - Gregory G King
- Woolcock Institute of Medical Research, Sydney, Australia.,University of Sydney, Sydney, Australia; and.,Cooperative Research Centre for Asthma, Sydney, Australia
| | - Louis-Philippe Boulet
- Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec, Québec, Canada
| | - Ynuk Bossé
- Institut Universitaire de Cardiologie et de Pneumologie de Québec, Université Laval, Québec, Québec, Canada;
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Cisonni J, Lucey AD, King AJC, Islam SMS, Lewis R, Goonewardene MS. Numerical simulation of pharyngeal airflow applied to obstructive sleep apnea: effect of the nasal cavity in anatomically accurate airway models. Med Biol Eng Comput 2015; 53:1129-39. [PMID: 26429351 DOI: 10.1007/s11517-015-1399-z] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2013] [Accepted: 09/19/2015] [Indexed: 11/26/2022]
Abstract
Repetitive brief episodes of soft-tissue collapse within the upper airway during sleep characterize obstructive sleep apnea (OSA), an extremely common and disabling disorder. Failure to maintain the patency of the upper airway is caused by the combination of sleep-related loss of compensatory dilator muscle activity and aerodynamic forces promoting closure. The prediction of soft-tissue movement in patient-specific airway 3D mechanical models is emerging as a useful contribution to clinical understanding and decision making. Such modeling requires reliable estimations of the pharyngeal wall pressure forces. While nasal obstruction has been recognized as a risk factor for OSA, the need to include the nasal cavity in upper-airway models for OSA studies requires consideration, as it is most often omitted because of its complex shape. A quantitative analysis of the flow conditions generated by the nasal cavity and the sinuses during inspiration upstream of the pharynx is presented. Results show that adequate velocity boundary conditions and simple artificial extensions of the flow domain can reproduce the essential effects of the nasal cavity on the pharyngeal flow field. Therefore, the overall complexity and computational cost of accurate flow predictions can be reduced.
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Affiliation(s)
- Julien Cisonni
- Fluid Dynamics Research Group, Department of Mechanical Engineering, Curtin University, Perth, WA, Australia.
| | - Anthony D Lucey
- Fluid Dynamics Research Group, Department of Mechanical Engineering, Curtin University, Perth, WA, Australia
| | - Andrew J C King
- Fluid Dynamics Research Group, Department of Mechanical Engineering, Curtin University, Perth, WA, Australia
| | - Syed Mohammed Shamsul Islam
- Fluid Dynamics Research Group, Department of Mechanical Engineering, Curtin University, Perth, WA, Australia
- School of Dentistry/Oral Health Centre of Western Australia, University of Western Australia, Crawley, WA, Australia
| | - Richard Lewis
- Perth Head and Neck Surgery, Nedlands, WA, Australia
| | - Mithran S Goonewardene
- School of Dentistry/Oral Health Centre of Western Australia, University of Western Australia, Crawley, WA, Australia
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Airway distension during lung inflation in healthy and allergic-sensitised mice in vivo. Respir Physiol Neurobiol 2012; 185:639-46. [PMID: 23253555 DOI: 10.1016/j.resp.2012.12.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2012] [Revised: 11/14/2012] [Accepted: 12/06/2012] [Indexed: 11/22/2022]
Abstract
We evaluated the airway distention during lung inflation of varying size in healthy and allergic-sensitised mice in vivo. Computed tomography (CT) images of healthy and ovalbumin-treated mice were acquired using a synchrotron in vivo CT system when lung pressures was 0 and 20 cmH(2)O, and the morphometric distension (diameter, length, and volume) and the compliance of airway segments (to as small as ~150 μm internal diameter) were calculated. With respect to airway size, in healthy mice, the changes in airway diameter and compliance were larger in the small-airway group. In contrast, in allergic-sensitised mice, there were no significant differences in the changes in airway distension or compliance. Airway wall thickness in allergic-sensitised mice increased significantly in all airway groups, but the change was much larger in the small than in the large-airway group. Compared with healthy airways, the changes in diameter and airway compliance of the allergic-sensitised mice were significantly smaller in the small-airway group.
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Abstract
PURPOSE OF REVIEW The small airways play an important yet poorly targeted role in asthma pathophysiology, leading to increased morbidity in asthma patients. Assessing inflammation and remodeling in these airways, determining the contribution of small airways to lung dysfunction and enhancing drug delivery to the distal regions of the lung remain challenging. The purpose of this review is to highlight recent advances in our understanding of small airways involvement in asthma. RECENT FINDINGS Inflammation in the small airways can be evaluated through exhaled gas measurements, most often nitric oxide. However, additional exhaled biomarkers have recently been described. Considerable infiltration of mast cells in the distal lung and extensive structural changes to the small airways have also been demonstrated. Advances have been made in the functional assessment of small airways, particularly in the measurement of small airway compliance and ventilation defects and in studies investigating the impact of small particle inhaled corticosteroid treatment on lung function. SUMMARY Experimental assessments of small airways inflammation, remodeling and function have provided novel insights into the importance of the distal regions of the lung in asthma pathology. Further advances in drug delivery to the small airways have the potential to improve asthma control.
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King GG. Current and emerging imaging in relation to drug discovery in airways disease. Pulm Pharmacol Ther 2011; 24:497-504. [DOI: 10.1016/j.pupt.2011.07.003] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2011] [Revised: 07/18/2011] [Accepted: 07/20/2011] [Indexed: 11/16/2022]
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Kelly VJ, Brown NJ, King GG, Thompson BR. The bronchodilator response of in vivo specific airway compliance in adults with asthma. Ann Biomed Eng 2010; 39:1125-35. [PMID: 21184178 DOI: 10.1007/s10439-010-0206-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2010] [Accepted: 11/08/2010] [Indexed: 11/28/2022]
Abstract
A new technique has been developed to determine in vivo airway compliance in humans that is specific to airway size and transpulmonary pressure, and can be represented as a three-dimensional surface. As yet, the ability of this technique to detect changes in specific airway compliance with disease status has not been demonstrated. The aim of this study was to assess whether this technique could determine changes in airway compliance which are thought to occur with altered smooth muscle tone in adults with asthma. Airway compliance was measured and displayed as a surface in adults with asthma before and after a reduction in smooth muscle tone by bronchodilator administration. Compliance, with respect to airway size, was calculated at three specific lung volumes; functional residual capacity (FRC), total lung capacity (TLC), and midway between FRC and TLC (MID). After bronchodilator, airway compliance increased at FRC and MID in the smaller airways (<3 mm). Furthermore, airway compliance under both conditions was greater in the smaller airways compared to the larger airways. In conclusion, our method may have future utility in assessing changes in airway compliance in respiratory diseases such as asthma.
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Affiliation(s)
- Vanessa J Kelly
- The Department of Medicine, Nursing and Health Sciences, Monash University, Clayton, VIC 3004, Australia
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