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Article ; Online: Propagation of an idealized infection in an airway tree, consequences of the inflammation on the oxygen transfer to blood.

Noël, Frédérique / Mauroy, Benjamin

2023 Volume 561, Page(s) 111405

Abstract: A mathematical model of infection, inflammation and immune response in an idealized bronchial tree is developed. This work is based on a model from the literature that is extended to account for the propagation dynamics of an infection between the ... ...

Abstract	A mathematical model of infection, inflammation and immune response in an idealized bronchial tree is developed. This work is based on a model from the literature that is extended to account for the propagation dynamics of an infection between the airways. The inflammation affects the size of the airways, the air flows distribution in the airway tree, and, consequently, the oxygen transfers to blood. We test different infections outcomes and propagation speed. In the hypotheses of our model, the inflammation can reduce notably and sometimes drastically the oxygen flow to blood. Our model predicts how the air flows and oxygen exchanges reorganize in the tree during an infection. Our results highlight the links between the localization of the infection and the amplitude of the loss of oxygen flow to blood. We show that a compensation phenomena due to the reorganization of the flow exists, but that it remains marginal unless the power produced the ventilation muscles is increased. Our model forms a first step towards a better understanding of the dynamics of bronchial infections.
MeSH term(s)	Humans ; Oxygen ; Lung/physiology ; Inflammation ; Models, Biological ; Models, Anatomic
Chemical Substances	Oxygen (S88TT14065)
Language	English
Publishing date	2023-01-10
Publishing country	England
Document type	Journal Article ; Research Support, Non-U.S. Gov't
ZDB-ID	2972-5
ISSN	1095-8541 ; 0022-5193
ISSN (online)	1095-8541
ISSN	0022-5193
DOI	10.1016/j.jtbi.2023.111405
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Article ; Online: Water and heat exchanges in mammalian lungs.

Haut, Benoit / Karamaoun, Cyril / Mauroy, Benjamin / Sobac, Benjamin

Scientific reports

2023 Volume 13, Issue 1, Page(s) 6636

Abstract: A secondary function of the respiratory system of the mammals is, during inspiration, to heat the air to body temperature and to saturate it with water before it reaches the alveoli. Relying on a mathematical model, we propose a comprehensive analysis of ...

Abstract	A secondary function of the respiratory system of the mammals is, during inspiration, to heat the air to body temperature and to saturate it with water before it reaches the alveoli. Relying on a mathematical model, we propose a comprehensive analysis of this function, considering all the terrestrial mammals (spanning six orders of magnitude of the body mass, M) and focusing on the sole contribution of the lungs to this air conditioning. The results highlight significant differences between the small and the large mammals, as well as between rest and effort, regarding the spatial distribution of heat and water exchanges in the lungs, and also in terms of regime of mass transfer taking place in the lumen of the airways. Interestingly, the results show that the mammalian lungs appear to be designed just right to fully condition the air at maximal effort (and clearly over-designed at rest, except for the smallest mammals): all generations of the bronchial region of the lungs are mobilized for this purpose, with calculated values of the local evaporation rate of water from the bronchial mucosa that can be very close to the maximal ability of the serous cells to replenish this mucosa with water. For mammals with a mass above a certain threshold ([Formula: see text] kg at rest and [Formula: see text] g at maximal effort), it appears that the maximal value of this evaporation rate scales as [Formula: see text] at rest and [Formula: see text] at maximal effort and that around 40% (at rest) or 50% (at maximal effort) of the water/heat extracted from the lungs during inspiration is returned to the bronchial mucosa during expiration, independently of the mass, due to a subtle coupling between different phenomena. This last result implies that, above these thresholds, the amounts of water and heat extracted from the lungs by the ventilation scale with the mass such as the ventilation rate does (i.e. as [Formula: see text] at rest and [Formula: see text] at maximal effort). Finally, it is worth to mention that these amounts appear to remain limited, but not negligible, when compared to relevant global quantities, even at maximal effort (4-6%).
MeSH term(s)	Animals ; Water ; Hot Temperature ; Respiratory Physiological Phenomena ; Bronchi ; Mammals
Chemical Substances	Water (059QF0KO0R)
Language	English
Publishing date	2023-04-24
Publishing country	England
Document type	Journal Article ; Research Support, Non-U.S. Gov't
ZDB-ID	2615211-3
ISSN	2045-2322 ; 2045-2322
ISSN (online)	2045-2322
ISSN	2045-2322
DOI	10.1038/s41598-023-33052-y
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Article: Interplay Between Optimal Ventilation and Gas Transport in a Model of the Human Lung.

Noël, Frédérique / Mauroy, Benjamin

Frontiers in physiology

2019 Volume 10, Page(s) 488

Abstract: Ventilation is at the origin of a spending of energy coming from air circulation in the bronchial tree and from the mechanical resistance of the tissue to motion. Both amplitude and frequency of ventilation are submitted to a trade-off related to this ... ...

Abstract	Ventilation is at the origin of a spending of energy coming from air circulation in the bronchial tree and from the mechanical resistance of the tissue to motion. Both amplitude and frequency of ventilation are submitted to a trade-off related to this energy, but they are also submitted to a constraint linked to the function of the lung: to transport enough oxygen and carbon dioxide in order to respect metabolism needs. We propose a model for oxygen and carbon dioxide transport in the lung that accounts for the core physical phenomena: lung's tree-like geometry, transport of gas by convection and diffusion, exchanges with blood and a sinusoidal ventilation. Then we optimize the power dissipated by the ventilation of our model relatively to ventilation amplitude and period under gas flow constraints. Our model is able to predict physiological ventilation properties and brings interesting insights on the robustness of different regimes. Hence, at rest, the power dissipated depends very little on the period near the optimal value. Whereas, at strong exercise any shift from the optimal has dramatic effect on the power. These results are fully coherent with the physiological observation and raises the question: how the control of ventilation could select for the optimal configuration? Also, interesting insights about pathologies affecting ventilation could be derived, and our model might give insights on therapeutical responses, with specific breathing strategies or for better driving mechanical ventilation.
Language	English
Publishing date	2019-04-26
Publishing country	Switzerland
Document type	Journal Article
ZDB-ID	2564217-0
ISSN	1664-042X
ISSN	1664-042X
DOI	10.3389/fphys.2019.00488
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Book ; Online: Influence of lung physical properties on its flow--volume curves using a detailed multi-scale mathematical model of the lung

Di Dio, Riccardo / Brunengo, Michaël / Mauroy, Benjamin

2022

Abstract: We develop a mathematical model of the lung that can estimate independently the air flows and pressures in the upper bronchi. It accounts for the lung multi-scale properties and for the air-tissue interactions. The model equations are solved using the ... ...

Abstract	We develop a mathematical model of the lung that can estimate independently the air flows and pressures in the upper bronchi. It accounts for the lung multi-scale properties and for the air-tissue interactions. The model equations are solved using the Discrete Fourier Transform, which allows quasi instantaneous solving, in the limit of the model hypotheses. With this model, we explore how the air flow--volume curves are affected by airways obstruction or by change in lung compliance. Our work suggests that a fine analysis of the flow-volume curves might bring information about the inner phenomena occurring in the lung.
Keywords	Quantitative Biology - Tissues and Organs
Publishing date	2022-05-24
Publishing country	us
Document type	Book ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Book ; Online: Wall shear stress distribution in a compliant airway tree

Stéphano, Jonathan / Mauroy, Benjamin

2020

Abstract: The airflow in the bronchi applies a shear stress on the bronchial mucus, which can move the mucus. The air--mucus interaction plays an important role in cough and in chest physiotherapy (CP). The conditions under which it induces a displacement of the ... ...

Abstract	The airflow in the bronchi applies a shear stress on the bronchial mucus, which can move the mucus. The air--mucus interaction plays an important role in cough and in chest physiotherapy (CP). The conditions under which it induces a displacement of the mucus are still unclear. Yet, the air--mucus interaction justifies common technics of CP used to help the draining of the mucus in prevalent diseases. Hence, the determination of the distribution of the shear stress in the lung is crucial for understanding the effects of these therapies and, potentially, improve their efficiency. We develop a mathematical model to study the distribution of the wall shear stress (WSS) induced by an air flow exiting an airway tree. This model accounts for the main physical processes that determines the WSS, more particularly the compliance of the airways, the air inertia and the tree structure. We show that the WSS distribution in the tree depends on the dynamics of the airways deformation and on the air inertia. The WSS distribution in the tree exhibits a maximum whose amplitude and location depend on the amount of air flow and on the "tissue" pressure surrounding the airways. To characterize the behavior of the WSS at the tree bifurcations, we derive new analytical criteria related to the airway size reduction in the bifurcations. Our results suggest that a tuning of the airflow and of the tissue pressure during a CP maneuver might allow to control, at least partially, the air--mucus interaction in the lung.
Keywords	Physics - Biological Physics ; Physics - Computational Physics ; Physics - Fluid Dynamics ; Quantitative Biology - Tissues and Organs
Subject code	690
Publishing date	2020-11-19
Publishing country	us
Document type	Book ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: The origin of the allometric scaling of lung ventilation in mammals

Noël, Frédérique / Karamaoun, Cyril / Dempsey, Jerome A. / Mauroy, Benjamin

Peer Community Journal, Vol 2, Iss , Pp - (2022)

2022

Abstract: A model of optimal control of ventilation has recently been developed for humans. This model highlights the importance of the localization of the transition between a convective and a diffusive transport of respiratory gas. This localization determines ... ...

Abstract	A model of optimal control of ventilation has recently been developed for humans. This model highlights the importance of the localization of the transition between a convective and a diffusive transport of respiratory gas. This localization determines how ventilation should be controlled in order to minimize its energetic cost at any metabolic regime. We generalized this model to any mammal, based on the core morphometric characteristics shared by all mammalian lungs and on their allometric scaling from the literature. Since the main energetic costs of ventilation are related to convective transport, we prove that, for all mammals, the localization of the shift from a convective transport to a diffusive transport plays a critical role on keeping this cost low while fulfilling the lung function. Our model predicts for the first time the localization of this transition in order to minimize the energetic cost of ventilation, depending on mammal mass and metabolic regime. From this optimal localization, we are able to predict allometric scaling laws for both tidal volumes and breathing rates, at any metabolic rate. We ran our model for the three common metabolic rates -- basal, field and maximal -- and showed that our predictions reproduce accurately experimental data available in the literature. Our analysis supports the hypothesis that mammals allometric scaling laws of tidal volumes and breathing rates at a given metabolic rate are driven by a few core geometrical characteristics shared by mammalian lungs and by the physical processes of respiratory gas transport.
Keywords	Archaeology ; CC1-960 ; Science ; Q
Subject code	510
Language	English
Publishing date	2022-01-01T00:00:00Z
Publisher	Peer Community In
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: The origin of the allometric scaling of lung ventilation in mammals

Noël, Frédérique / Karamaoun, Cyril / Dempsey, Jerome A. / Mauroy, Benjamin

Peer Community Journal, Vol 2, Iss , Pp - (2022)

2022

Abstract	A model of optimal control of ventilation has recently been developed for humans. This model highlights the importance of the localization of the transition between a convective and a diffusive transport of respiratory gas. This localization determines how ventilation should be controlled in order to minimize its energetic cost at any metabolic regime. We generalized this model to any mammal, based on the core morphometric characteristics shared by all mammalian lungs and on their allometric scaling from the literature. Since the main energetic costs of ventilation are related to convective transport, we prove that, for all mammals, the localization of the shift from a convective transport to a diffusive transport plays a critical role on keeping this cost low while fulfilling the lung function. Our model predicts for the first time the localization of this transition in order to minimize the energetic cost of ventilation, depending on mammal mass and metabolic regime. From this optimal localization, we are able to predict allometric scaling laws for both tidal volumes and breathing rates, at any metabolic rate. We ran our model for the three common metabolic rates -- basal, field and maximal -- and showed that our predictions reproduce accurately experimental data available in the literature. Our analysis supports the hypothesis that mammals allometric scaling laws of tidal volumes and breathing rates at a given metabolic rate are driven by a few core geometrical characteristics shared by mammalian lungs and by the physical processes of respiratory gas transport.
Keywords	Archaeology ; CC1-960 ; Science ; Q
Subject code	510
Language	English
Publishing date	2022-01-01T00:00:00Z
Publisher	Peer Community In
Document type	Article ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: Is airway damage during physical exercise related to airway dehydration? Inputs from a computational model.

Karamaoun, Cyril / Haut, Benoît / Blain, Grégory / Bernard, Alfred / Daussin, Frédéric / Dekerle, Jeanne / Bougault, Valérie / Mauroy, Benjamin

Journal of applied physiology (Bethesda, Md. : 1985)

2022 Volume 132, Issue 4, Page(s) 1031–1040

Abstract: In healthy subjects, at low minute ventilation (V̇e) during physical exercise, the water content and temperature of the airways are well regulated. However, with the increase in V̇e, the bronchial mucosa becomes dehydrated and epithelial damage occurs. ... ...

Abstract	In healthy subjects, at low minute ventilation (V̇e) during physical exercise, the water content and temperature of the airways are well regulated. However, with the increase in V̇e, the bronchial mucosa becomes dehydrated and epithelial damage occurs. Our goal was to demonstrate the correspondence between the ventilatory threshold inducing epithelial damage, measured experimentally, and the dehydration threshold, estimated numerically. In 16 healthy adults, we assessed epithelial damage before and following a 30-min continuous cycling exercise at 70% of maximal work rate, by measuring the variation pre- to postexercise of serum club cell protein (cc16/cr). Blood samples were collected at rest, just at the end of the standardized 10-min warm-up, and immediately, 30 min and 60 min postexercise. Mean V̇e during exercise was kept for analysis. Airway water and heat losses were estimated using a computational model adapted to the experimental conditions and were compared with a literature-based threshold of bronchial dehydration. Eleven participants exceeded the threshold for bronchial dehydration during exercise (
MeSH term(s)	Adult ; Bronchoconstriction ; Dehydration ; Exercise ; Exercise Test/methods ; Humans ; Water
Chemical Substances	Water (059QF0KO0R)
Language	English
Publishing date	2022-02-24
Publishing country	United States
Document type	Journal Article ; Research Support, N.I.H., Extramural
ZDB-ID	219139-8
ISSN	1522-1601 ; 0021-8987 ; 0161-7567 ; 8750-7587
ISSN (online)	1522-1601
ISSN	0021-8987 ; 0161-7567 ; 8750-7587
DOI	10.1152/japplphysiol.00520.2021
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Book ; Online: Curvature-induced motion of a thin Bingham layer in airways bifurcations

Karamaoun, Cyril / Kumar, Haribalan / Argentina, Médéric / Clamond, Didier / Mauroy, Benjamin

2021

Abstract: The mucus on the bronchial wall forms a thin layer of a non-Newtonian fluid protecting the lung by capturing inhaled pollutants. Due to the corrugation of its interface with air, this layer is subject to surface tensions affecting its rheology. This ... ...

Abstract	The mucus on the bronchial wall forms a thin layer of a non-Newtonian fluid protecting the lung by capturing inhaled pollutants. Due to the corrugation of its interface with air, this layer is subject to surface tensions affecting its rheology. This physical system is analyzed via the lubrication theory and 3D simulations. We characterize the mucus nonlinear behavior and show that surface tension effects can displace overly thick mucus layers in the airway bifurcations. Thus, this movement can disrupt the mucociliary clearance and break the layer thickness homogeneity.
Keywords	Physics - Fluid Dynamics ; Physics - Biological Physics ; Physics - Computational Physics ; Quantitative Biology - Tissues and Organs
Publishing date	2021-12-21
Publishing country	us
Document type	Book ; Online
Database	BASE - Bielefeld Academic Search Engine (life sciences selection)

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Article ; Online: An archetypal mechanism for branching organogenesis.

Clément, Raphaël / Mauroy, Benjamin

Physical biology

2014 Volume 11, Issue 1, Page(s) 16003

Abstract: Branched structures are ubiquitous in nature, both in living and non-living systems. While the functional benefits of branching organogenesis are straightforward, the developmental mechanisms leading to the repeated branching of epithelia in surrounding ... ...

Abstract	Branched structures are ubiquitous in nature, both in living and non-living systems. While the functional benefits of branching organogenesis are straightforward, the developmental mechanisms leading to the repeated branching of epithelia in surrounding mesoderm remain unclear. Both molecular and physical aspects of growth control seem to play a critical role in shape emergence and maintenance. On the molecular side, the existence of a gradient of growth-promoting ligand between epithelial tips and distal mesenchyme seems to be common to branched organs. On the physical side, the branching process seems to require a mechanism of real-time adaptation to local geometry, as suggested by the self-avoiding nature of branching events. In this paper, we investigate the outcomes of a general three-dimensional growth model, in which epithelial growth is implemented as a function of ligand income, while the mesenchyme is considered as a proliferating viscous medium. Our results suggest that the existence of a gradient of growth-promoting ligand between distal and proximal mesenchyme implies a growth instability of the epithelial sheet, resulting in spontaneous self-avoiding branching morphogenesis. While the general nature of the model prevents one from fitting the development of specific organs, it suggests that few ingredients are actually required to achieve branching organogenesis.
MeSH term(s)	Animals ; Cell Proliferation ; Epithelial Cells/cytology ; Epithelial Cells/metabolism ; Ligands ; Mesoderm/cytology ; Mesoderm/metabolism ; Mice ; Models, Biological ; Organogenesis
Chemical Substances	Ligands
Language	English
Publishing date	2014-02
Publishing country	England
Document type	Journal Article ; Research Support, Non-U.S. Gov't
ZDB-ID	2133216-2
ISSN	1478-3975 ; 1478-3967
ISSN (online)	1478-3975
ISSN	1478-3967
DOI	10.1088/1478-3975/11/1/016003
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