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Abrami M, Biasin A, Tescione F, Tierno D, Dapas B, Carbone A, Grassi G, Conese M, Di Gioia S, Larobina D, Grassi M. Mucus Structure, Viscoelastic Properties, and Composition in Chronic Respiratory Diseases. Int J Mol Sci 2024; 25:1933. [PMID: 38339210 PMCID: PMC10856136 DOI: 10.3390/ijms25031933] [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: 12/31/2023] [Revised: 01/25/2024] [Accepted: 01/31/2024] [Indexed: 02/12/2024] Open
Abstract
The respiratory mucus, a viscoelastic gel, effectuates a primary line of the airway defense when operated by the mucociliary clearance. In chronic respiratory diseases (CRDs), such as asthma, chronic obstructive pulmonary disease (COPD), and cystic fibrosis (CF), the mucus is overproduced and its solid content augments, changing its structure and viscoelastic properties and determining a derangement of essential defense mechanisms against opportunistic microbial (virus and bacteria) pathogens. This ensues in damaging of the airways, leading to a vicious cycle of obstruction and infection responsible for the harsh clinical evolution of these CRDs. Here, we review the essential features of normal and pathological mucus (i.e., sputum in CF, COPD, and asthma), i.e., mucin content, structure (mesh size), micro/macro-rheology, pH, and osmotic pressure, ending with the awareness that sputum biomarkers (mucins, inflammatory proteins and peptides, and metabolites) might serve to indicate acute exacerbation and response to therapies. There are some indications that old and novel treatments may change the structure, viscoelastic properties, and biomarker content of sputum; however, a wealth of work is still needed to embrace these measures as correlates of disease severity in association with (or even as substitutes of) pulmonary functional tests.
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Affiliation(s)
- Michela Abrami
- Department of Engineering and Architecture, University of Trieste, Via Valerio 6/A, I-34127 Trieste, Italy; (M.A.); (A.B.); (M.G.)
| | - Alice Biasin
- Department of Engineering and Architecture, University of Trieste, Via Valerio 6/A, I-34127 Trieste, Italy; (M.A.); (A.B.); (M.G.)
| | - Fabiana Tescione
- Institute of Polymers, Composites and Biomaterials, National Research Council of Italy, P.le E. Fermi 1, I-80055 Portici, Italy; (F.T.); (D.L.)
| | - Domenico Tierno
- Clinical Department of Medical, Surgical and Health Sciences, Cattinara University Hospital, University of Trieste, Strada di Fiume 447, I-34149 Trieste, Italy; (D.T.); (G.G.)
| | - Barbara Dapas
- Department of Chemical and Pharmaceutical Sciences, University of Trieste, Via L. Giorgieri 1, I-34127 Trieste, Italy;
| | - Annalucia Carbone
- Department of Clinical and Experimental Medicine, University of Foggia, Via Napoli 121, I-71122 Foggia, Italy; (A.C.); (S.D.G.)
| | - Gabriele Grassi
- Clinical Department of Medical, Surgical and Health Sciences, Cattinara University Hospital, University of Trieste, Strada di Fiume 447, I-34149 Trieste, Italy; (D.T.); (G.G.)
| | - Massimo Conese
- Department of Clinical and Experimental Medicine, University of Foggia, Via Napoli 121, I-71122 Foggia, Italy; (A.C.); (S.D.G.)
| | - Sante Di Gioia
- Department of Clinical and Experimental Medicine, University of Foggia, Via Napoli 121, I-71122 Foggia, Italy; (A.C.); (S.D.G.)
| | - Domenico Larobina
- Institute of Polymers, Composites and Biomaterials, National Research Council of Italy, P.le E. Fermi 1, I-80055 Portici, Italy; (F.T.); (D.L.)
| | - Mario Grassi
- Department of Engineering and Architecture, University of Trieste, Via Valerio 6/A, I-34127 Trieste, Italy; (M.A.); (A.B.); (M.G.)
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Sedaghat MH, Behnia M, Abouali O. Nanoparticle Diffusion in Respiratory Mucus Influenced by Mucociliary Clearance: A Review of Mathematical Modeling. J Aerosol Med Pulm Drug Deliv 2023. [PMID: 37184652 DOI: 10.1089/jamp.2022.0049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2023] Open
Abstract
Background: Inhalation and deposition of particles in human airways have attracted considerable attention due to importance of particulate pollutants, transmission of infectious diseases, and therapeutic delivery of drugs at targeted areas. We summarize current state-of-the art research in particle deposition on airway surface liquid (ASL) influenced by mucociliary clearance (MCC) by identifying areas that need further investigation. Methodology: We aim to review focus on governing and constitutive equations describing MCC geometry followed by description of mathematical modeling of ciliary forces, mucus rheology properties, and numerical approaches to solve modified time-dependent Navier-Stokes equations. We also review mathematical modeling of particle deposition in ASL influenced by MCC, particle transport in ASL in terms of Eulerian and Lagrangian approaches, and discuss the corresponding mass transport issues in this layer. Whenever required, numerical predictions are contrasted with the pertinent experimental data. Results: Results indicate that mean mucus and periciliary liquid velocities are strongly influenced by mucus rheological characteristics as well as ciliary abnormalities. However, most of the currently available literature on mucus fiber spacing, ciliary beat frequency, and particle surface chemistry is based on particle deposition on ASL by considering a fixed value of ASL velocity. The effects of real ASL flow regimes on particle deposition in this layer are limited. In addition, no other study is available on modeling nonhomogeneous and viscoelastic characteristics of mucus layer on ASL drug delivery. Conclusion: Simplification of assumptions on governing equations of drug delivery in ASL influenced by MCC leads to imposing some limitations on numerical results.
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Affiliation(s)
- Mohammad Hadi Sedaghat
- Department of Mechanical Engineering, Technical and Vocational University (TVU), Tehran, Iran
| | - Mehrdad Behnia
- University of Central Florida School of Medicine, Orlando, Florida, USA
| | - Omid Abouali
- Department of Civil and Architectural Engineering, KTH Royal Institute of Technology, Stockholm, Sweden
- School of Mechanical Engineering, Shiraz University, Shiraz, Iran
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Tauwald SM, Michel J, Brandt M, Vielsmeier V, Stemmer C, Krenkel L. Experimental studies and mathematical modeling of the viscoelastic rheology of tracheobronchial mucus from respiratory healthy patients. Multidiscip Respir Med 2023; 18:923. [PMID: 37908973 PMCID: PMC10615166 DOI: 10.4081/mrm.2023.923] [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] [Received: 06/06/2023] [Accepted: 08/30/2023] [Indexed: 11/02/2023] Open
Abstract
Background Tracheobronchial mucus plays a crucial role in pulmonary function by providing protection against inhaled pathogens. Due to its composition of water, mucins, and other biomolecules, it has a complex viscoelastic rheological behavior. This interplay of both viscous and elastic properties has not been fully described yet. In this study, we characterize the rheology of human mucus using oscillatory and transient tests. Based on the transient tests, we describe the material behavior of mucus under stress and strain loading by mathematical models. Methods Mucus samples were collected from clinically used endotracheal tubes. For rheological characterization, oscillatory amplitude-sweep and frequency-sweep tests, and transient creep-recovery and stress-relaxation tests were performed. The results of the transient test were approximated using the Burgers model, the Weibull distribution, and the six-element Maxwell model. The three-dimensional microstructure of the tracheobronchial mucus was visualized using scanning electron microscope imaging. Results Amplitude-sweep tests showed storage moduli ranging from 0.1 Pa to 10,000 Pa and a median critical strain of 4%. In frequency-sweep tests, storage and loss moduli increased with frequency, with the median of the storage modulus ranging from 10 Pa to 30 Pa, and the median of the loss modulus from 5 Pa to 14 Pa. The Burgers model approximates the viscoelastic behavior of tracheobronchial mucus during a constant load of stress appropriately (R2 of 0.99), and the Weibull distribution is suitable to predict the recovery of the sample after the removal of this stress (R2 of 0.99). The approximation of the stress-relaxation test data by a six-element Maxwell model shows a larger fit error (R2 of 0.91). Conclusions This study provides a detailed description of all process steps of characterizing the rheology of tracheobronchial mucus, including sample collection, microstructure visualization, and rheological investigation. Based on this characterization, we provide mathematical models of the rheological behavior of tracheobronchial mucus. These can now be used to simulate mucus flow in the respiratory system through numerical approaches.
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Affiliation(s)
- Sandra Melina Tauwald
- Regensburg Center of Health Sciences and Technology, Department of Biofluid Mechanics, University of Applied Sciences (OTH), Regensburg
| | - Johanna Michel
- Regensburg Center of Health Sciences and Technology, Department of Biofluid Mechanics, University of Applied Sciences (OTH), Regensburg
| | - Marie Brandt
- Department for Otorhinolaryngology, University Hospital Regensburg, Regensburg
| | - Veronika Vielsmeier
- Department for Otorhinolaryngology, University Hospital Regensburg, Regensburg
| | - Christian Stemmer
- Chair of Aerodynamics and Fluid Mechanics, Technical University of Munich (TUM), Munich, Germany
| | - Lars Krenkel
- Regensburg Center of Health Sciences and Technology, Department of Biofluid Mechanics, University of Applied Sciences (OTH), Regensburg
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Gutmark E, Anand V, Wheeler A, Zahn A, Cavari Y, Eluk T, Hay M, Katoshevski D, Gutmark-Little I. Demonstration of mucus simulant clearance in a Bench-Model using acoustic Field-Integrated Intrapulmonary Percussive ventilation. J Biomech 2022; 144:111305. [PMID: 36137371 DOI: 10.1016/j.jbiomech.2022.111305] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2021] [Revised: 09/08/2022] [Accepted: 09/11/2022] [Indexed: 11/24/2022]
Abstract
Intrapulmonary Percussive Ventilation (IPV) is a high-frequency airway clearance technique used to help in mucus transport for mechanically ventilated and unventilated patients. Despite the many years of usage, this technique does not provide clear evidence of its intended efficacy. This is mainly attributable to the lack of in vitro observations that show "mucokinesis" towards the direction of the mouth. In the current manuscript, we demonstrate and subsequently propose a mechanism that details the movement of a mucus simulant in the proximal (towards the mouthpiece) direction. Towards this end, a novel method utilizing a high-frequency acoustic field in addition to the conventional air pulsations brought forth by traditional IPV is proposed. Under these conditions, at certain parameter settings, it is shown that the simulant is broken down into much smaller parts and subsequently pushed in the upstream direction gradually over a period of half-hour.
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Affiliation(s)
- Ephraim Gutmark
- Department of Aerospace Engineering and Engineering Mechanics, University of Cincinnati, Cincinnati, OH 45221, USA.
| | - Vijay Anand
- Department of Aerospace Engineering and Engineering Mechanics, University of Cincinnati, Cincinnati, OH 45221, USA
| | - Aaron Wheeler
- Department of Aerospace Engineering and Engineering Mechanics, University of Cincinnati, Cincinnati, OH 45221, USA
| | - Alexander Zahn
- Department of Aerospace Engineering and Engineering Mechanics, University of Cincinnati, Cincinnati, OH 45221, USA
| | - Yuval Cavari
- Pediatric Intensive Care Unit, Soroka Medical Center, Beer-Sheva, Israel
| | - Tal Eluk
- Environmental Engineering Unit, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Maor Hay
- Environmental Engineering Unit, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - David Katoshevski
- Environmental Engineering Unit, Ben-Gurion University of the Negev, Beer-Sheva, Israel
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Coupled discrete phase model and Eulerian wall film model for numerical simulation of respiratory droplet generation during coughing. Sci Rep 2022; 12:14849. [PMID: 36050319 PMCID: PMC9434508 DOI: 10.1038/s41598-022-18788-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2022] [Accepted: 08/19/2022] [Indexed: 11/26/2022] Open
Abstract
Computational fluid dynamics is widely used to simulate droplet-spreading behavior due to respiratory events. However, droplet generation inside the body, such as the number, mass, and particle size distribution, has not been quantitatively analyzed. The aim of this study was to identify quantitative characteristics of droplet generation during coughing. Airflow simulations were performed by coupling the discrete phase model and Eulerian wall film model to reproduce shear-induced stripping of airway mucosa. An ideal airway model with symmetric bifurcations was constructed, and the wall domain was covered by a mucous liquid film. The results of the transient airflow simulation indicated that the droplets had a wide particle size distribution of 0.1–400 µm, and smaller droplets were generated in larger numbers. In addition, the total mass and number of droplets generated increased with an increasing airflow. The total mass of the droplets also increased with an increasing mucous viscosity, and the largest number and size of droplets were obtained at a viscosity of 8 mPa s. The simulation methods used in this study can be used to quantify the particle size distribution and maximum particle diameter under various conditions.
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Alginate as a Promising Biopolymer in Drug Delivery and Wound Healing: A Review of the State-of-the-Art. Int J Mol Sci 2022; 23:ijms23169035. [PMID: 36012297 PMCID: PMC9409034 DOI: 10.3390/ijms23169035] [Citation(s) in RCA: 47] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Revised: 08/07/2022] [Accepted: 08/09/2022] [Indexed: 12/20/2022] Open
Abstract
Biopolymeric nanoparticulate systems hold favorable carrier properties for active delivery. The enhancement in the research interest in alginate formulations in biomedical and pharmaceutical research, owing to its biodegradable, biocompatible, and bioadhesive characteristics, reiterates its future use as an efficient drug delivery matrix. Alginates, obtained from natural sources, are the colloidal polysaccharide group, which are water-soluble, non-toxic, and non-irritant. These are linear copolymeric blocks of α-(1→4)-linked l-guluronic acid (G) and β-(1→4)-linked d-mannuronic acid (M) residues. Owing to the monosaccharide sequencing and the enzymatically governed reactions, alginates are well-known as an essential bio-polymer group for multifarious biomedical implementations. Additionally, alginate’s bio-adhesive property makes it significant in the pharmaceutical industry. Alginate has shown immense potential in wound healing and drug delivery applications to date because its gel-forming ability maintains the structural resemblance to the extracellular matrices in tissues and can be altered to perform numerous crucial functions. The initial section of this review will deliver a perception of the extraction source and alginate’s remarkable properties. Furthermore, we have aspired to discuss the current literature on alginate utilization as a biopolymeric carrier for drug delivery through numerous administration routes. Finally, the latest investigations on alginate composite utilization in wound healing are addressed.
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Kumar R, Tokas S, Hadda V, Rakshit D, Sarkar J. Numerical modeling and development of a dual lung simulator using partitioned fluid-structure interaction approach for ventilator testing. INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING 2022; 38:e3607. [PMID: 35485138 DOI: 10.1002/cnm.3607] [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: 08/02/2021] [Revised: 12/29/2021] [Accepted: 04/20/2022] [Indexed: 06/14/2023]
Abstract
New designs of mechanical ventilators require extensive testing before utilizing the ventilator on a patient. Test lungs are commonly used to understand the behavior of new designs of ventilators and the lung mechanics. The current study aims to develop a numerical model of dual test lungs utilizing the partitioned fluid-structure interaction (FSI) approach and test it against the available experimental data of volume-controlled ventilation. Two breathing rates of 12 and 18 bpm were studied at two different tidal volumes of 500 and 600 ml for spontaneous breathing. It is found that with an increase in the compliance (tidal volume/pressure rise) of the lung, the peak pressure rise inside the test lung decreases irrespective of the breathing rate. The maximum average pressure of 44.73, 27.45, and 14 cm H2 O is observed for static lung compliances of 10, 21 , and 39 ml/cm H2 O, respectively at a tidal volume of 600 ml. Similarly, the maximum von-misses stress was higher (498 kPa) for the lung with lower compliance (10 ml/cm H2 O) as compared to the lung with higher compliance (39 ml/cm H2 O) at the end of inspiration. This study forms a basis for using computational methods to model simple lung simulators that can effectively investigate the lung mechanics for both spontaneous and ventilated breathing. Thus, it can be utilized as a reference to test novel designs of mechanical ventilators.
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Affiliation(s)
- Rahul Kumar
- Department of Chemical Engineering, Indian Institute of Technology Delhi, New Delhi, India
| | - Sulekh Tokas
- Department of Chemical Engineering, Indian Institute of Technology Delhi, New Delhi, India
| | - Vijay Hadda
- Department of Pulmonary, Critical Care and Sleep Medicine, All India Institute of Medical Sciences, New Delhi, India
| | - Dibakar Rakshit
- Department of Energy Science and Engineering, Indian Institute of Technology Delhi, New Delhi, India
| | - Jayati Sarkar
- Department of Chemical Engineering, Indian Institute of Technology Delhi, New Delhi, India
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8
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Effect of chest physiotherapy on cystic fibrosis sputum nanostructure: an experimental and theoretical approach. Drug Deliv Transl Res 2022; 12:1943-1958. [PMID: 35286625 PMCID: PMC9242959 DOI: 10.1007/s13346-022-01131-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/04/2022] [Indexed: 11/26/2022]
Abstract
Cystic fibrosis (CF) is a disease characterized by the production of viscous mucoid secretions in multiple organs, particularly the airways. The pathological increase of proteins, mucin and biological polymers determines their arrangement into a three-dimensional polymeric network, affecting the whole mucus and impairing the muco-ciliary clearance which promotes inflammation and bacterial infection. Thus, to improve the efficacy of the drugs usually applied in CF therapy (e.g., mucolytics, anti-inflammatory and antibiotics), an in-depth understanding of the mucus nanostructure is of utmost importance. Drug diffusivity inside a gel-like system depends on the ratio between the diffusing drug molecule radius and the mesh size of the network. Based on our previous findings, we propose the combined use of rheology and low field NMR to study the mesh size distribution of the sputum from CF patients. Specifically, we herein explore the effects of chest physiotherapy on CF sputum characteristic as evaluated by rheology, low field NMR and the drug penetration through the mucus via mathematical simulation. These data show that chest physiotherapy has beneficial effects on patients, as it favourably modifies sputum and enhances drug penetration through the respiratory mucus.
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Pramanik S, Mohanto S, Manne R, Rajendran RR, Deepak A, Edapully SJ, Patil T, Katari O. Nanoparticle-Based Drug Delivery System: The Magic Bullet for the Treatment of Chronic Pulmonary Diseases. Mol Pharm 2021; 18:3671-3718. [PMID: 34491754 DOI: 10.1021/acs.molpharmaceut.1c00491] [Citation(s) in RCA: 47] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Chronic pulmonary diseases encompass different persistent and lethal diseases, including chronic obstructive pulmonary disease (COPD), idiopathic pulmonary fibrosis (IPF), cystic fibrosis (CF), asthma, and lung cancers that affect millions of people globally. Traditional pharmacotherapeutic treatment approaches (i.e., bronchodilators, corticosteroids, chemotherapeutics, peptide-based agents, etc.) are not satisfactory to cure or impede diseases. With the advent of nanotechnology, drug delivery to an intended site is still difficult, but the nanoparticle's physicochemical properties can accomplish targeted therapeutic delivery. Based on their surface, size, density, and physical-chemical properties, nanoparticles have demonstrated enhanced pharmacokinetics of actives, achieving the spotlight in the drug delivery research field. In this review, the authors have highlighted different nanoparticle-based therapeutic delivery approaches to treat chronic pulmonary diseases along with the preparation techniques. The authors have remarked the nanosuspension delivery via nebulization and dry powder carrier is further effective in the lung delivery system since the particles released from these systems are innumerable to composite nanoparticles. The authors have also outlined the inhaled particle's toxicity, patented nanoparticle-based pulmonary formulations, and commercial pulmonary drug delivery devices (PDD) in other sections. Recently advanced formulations employing nanoparticles as therapeutic carriers for the efficient treatment of chronic pulmonary diseases are also canvassed.
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Affiliation(s)
- Sheersha Pramanik
- Department of Pharmacy, Institute of Pharmacy Jalpaiguri, Netaji Subhas Chandra Bose Road, Hospital Para, Jalpaiguri, West Bengal 735101, India.,Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences, Indian Institute of Technology Madras, Chennai, Tamil Nadu 600036, India
| | - Sourav Mohanto
- Department of Pharmaceutics, Himalayan Pharmacy Institute, Majhitar, East Sikkim 737176, India.,Department of Pharmaceutics, Yenepoya Pharmacy College and Research Centre, Yenepoya, Mangalore, Karnataka 575018, India
| | - Ravi Manne
- Quality Control and Assurance Department, Chemtex Environmental Lab, 3082 25th Street, Port Arthur, Texas 77642, United States
| | - Rahul R Rajendran
- Department of Mechanical Engineering and Mechanics, Lehigh University, 19 Memorial Drive West, Bethlehem, Pennsylvania 18015, United States
| | - A Deepak
- Saveetha Institute of Medical and Technical Sciences, Saveetha School of Engineering, Chennai, Tamil Nadu 600128, India
| | - Sijo Joy Edapully
- School of Biotechnology, National Institute of Technology Calicut, NIT campus, Kozhikode, Kerala 673601, India.,Corporate Head Office, HLL Lifecare Limited, Poojappura, Thiruvananthapuram, Kerala 695012, India
| | - Triveni Patil
- Department of Pharmaceutics, Bharati Vidyapeeth Deemed University, Poona College of Pharmacy, Erandwane, Pune, Maharashtra 411038, India
| | - Oly Katari
- Department of Pharmaceutics, National Institute of Pharmaceutical Education and Research (NIPER)-Guwahati, Sila Katamur (Halugurisuk), Changsari, Kamrup, Guwahati, Assam 781101, India
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Rajendran RR, Banerjee A. Effect of Non-Newtonian Dynamics on the Clearance of Mucus From Bifurcating Lung Airway Models. J Biomech Eng 2021; 143:021011. [PMID: 32959056 DOI: 10.1115/1.4048474] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Indexed: 11/08/2022]
Abstract
Mucus hypersecretion is a common pathophysiological manifestation of several obstructive airway diseases in which the mucociliary clearance is impaired, and the airflow generated by a cough or a forced expiratory maneuver called the huff is primarily responsible for clearing mucus. This airflow driven clearance of mucus is a complex process that is affected by the mucus rheology, airflow rate, airway geometry, and gravity. This study examines the role of mucus rheology in the transport and distribution of mucus in idealized 3D airway geometries. The complex air-mucus interface was tracked by the volume-of-fluid (VOF) model, and the turbulence in the core airflow was modeled using the k-ω shear stress transport (SST) model. Mucus was modeled as a shear-thinning liquid by using a power-law model. The computational model was validated using in vitro experimental data available in the literature. Gravity-dominated eccentric core-annular flow was observed with the core biased toward the outer wall in the inclined daughter branches of the bifurcation models, which transitions into concentric core-annular flow in the trachea. The increase in tangential shear at the interface due to the secondary flow structures developed in the flow divider location resulted in a region of enhanced mucus clearance with reduced mucus layer thickness. Secondary flow developed due to the curvature in the airway geometry resulted in a local redistribution of mucus that reduced the eccentricity. The accumulation of mucus around the carinal ridges and the regions with reduced clearance are sites with the potential for microbial growth.
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Affiliation(s)
- Rahul R Rajendran
- Mem. ASME Department of Mechanical Engineering & Mechanics, Lehigh University, Bethlehem, PA 18015
| | - Arindam Banerjee
- Mem. ASME Department of Mechanical Engineering & Mechanics, Lehigh University, 19 Memorial Drive WestBethlehem, PA 18015
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11
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Kelly SJ, Brodecky V, Skuza EM, Berger PJ, Tatkov S. Variability in tracheal mucociliary transport is not controlled by beating cilia in lambs in vivo during ventilation with humidified and nonhumidified air. Am J Physiol Lung Cell Mol Physiol 2021; 320:L473-L485. [PMID: 33438520 DOI: 10.1152/ajplung.00485.2020] [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: 11/22/2022] Open
Abstract
Mucociliary transport in the respiratory epithelium depends on beating of cilia to move a mucus layer containing trapped inhaled particles toward the mouth. Little is known about the relationship between cilia beat frequency (CBF) and mucus transport velocity (MTV) in vivo under normal physiological conditions and when inspired air is dry or not fully humidified. This study was designed to use video-microscopy to simultaneously measure CBF and MTV in the tracheal epithelium through an implanted optical window in mechanically ventilated lambs. The inspired air in 6 animals was heated to body temperature and fully saturated with water for 4 hours as a baseline. In another series of experiments, 5 lambs were ventilated with air at different temperatures and humidities and the mucosal surface temperature was monitored with infrared macro-imaging. In the baseline experiments, during ventilation with fully humidified air at body temperature, CBF remained constant, mean 13.9 ± 1.6 Hz but MTV varied considerably between 0.1 and 26.1 mm/min with mean 11.0 ± 3.9 mm/min, resulting in a maximum mucus displacement of 34.2 µm/cilia beat. Fully humidified air at body temperature prevented fluctuations in the surface temperature during breathing indicating a thermodynamic balance in the airways. When lambs were ventilated with dryer air, the mucosal surface temperature and MTV dropped without a significant change in CBF. When inspired air was dry, mainly latent heat (92%) was transferred to air in the trachea, reducing the surface temperature by 5 °C. Reduced humidity of the inspired air lowered the surface temperature and reduced MTV in the epithelium during ventilation.
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Affiliation(s)
- S J Kelly
- Fisher & Paykel Healthcare, Auckland, New Zealand
| | - V Brodecky
- Institute of Medical Research, Monash University, Melbourne, Victoria, Australia
| | - E M Skuza
- Institute of Medical Research, Monash University, Melbourne, Victoria, Australia
| | - P J Berger
- Institute of Medical Research, Monash University, Melbourne, Victoria, Australia
| | - S Tatkov
- Fisher & Paykel Healthcare, Auckland, New Zealand
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Zhang W, Xiang Y, Lu C, Ou C, Deng Q. Numerical modeling of particle deposition in the conducting airways of asthmatic children. Med Eng Phys 2019; 76:40-46. [PMID: 31879223 DOI: 10.1016/j.medengphy.2019.10.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Revised: 09/30/2019] [Accepted: 10/20/2019] [Indexed: 02/05/2023]
Abstract
Mounting evidence has linked long- and short-term exposure to particulate air pollution with the incidence and exacerbation of asthma in children, but the biological pathogenesis is unclear. We examined the deposition of particles in the airways of asthmatic children. A planar and symmetric model of airways for 4-year-old asthmatic children was considered. Airflow and particle deposition in the upper (G3-G6) and lower (G9-G12) conducting airways were numerically investigated using computation fluid dynamics (CFD) method. We considered the manifestation of moderate (30% reduction in airway diameter) and severe (60% reduction) asthma. Micron particles (1-10 µm) were considered. We found that particle deposition in the asthmatic children was significantly higher than that in healthy children. The deposition efficiency increased slowly with particle size for healthy children, but increased rapidly for asthmatic children, such that smaller particles could be deposited in the conducting airways of asthmatics. For healthy children, particles were deposited by inertial impaction and gravitational sedimentation respectively in the upper and lower airways, but deposited by inertial impaction in asthmatic children. The severity of the asthma increased the particle deposition in the airways. Our study indicated that asthmatic children were more susceptible to the effect of particulate air pollution. The constricted airways increased the particle deposition by inertial impaction, which may be the biological pathogenesis that causes the hospitalization of asthma in children. Avoiding exposure during air pollution events will be an effective measure to reduce the asthma attack.
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Affiliation(s)
- Wenwen Zhang
- School of Energy Science and Engineering, Central South University, Changsha 410083, China
| | - Yuguang Xiang
- School of Energy Science and Engineering, Central South University, Changsha 410083, China
| | - Chan Lu
- School of Energy Science and Engineering, Central South University, Changsha 410083, China; XiangYa School of Public Health, Central South University, Changsha 410078, China
| | - Cuiyun Ou
- School of Energy Science and Engineering, Central South University, Changsha 410083, China; School of Atmospheric Sciences, Sun Yat-Sen University, Guangzhou 510275, China
| | - Qihong Deng
- School of Energy Science and Engineering, Central South University, Changsha 410083, China; XiangYa School of Public Health, Central South University, Changsha 410078, China; School of Public Health, Zhengzhou University, Zhengzhou 450001, China; School of School of Architecture and Art, Central South University, Changsha 410083, China.
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