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Soltani M. Capillary network formation and structure in a modified discrete mathematical model of angiogenesis. Biomed Phys Eng Express 2021; 8. [PMID: 34883475 DOI: 10.1088/2057-1976/ac4175] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Accepted: 12/09/2021] [Indexed: 01/01/2023]
Abstract
Angiogenesis, as part of cancer development, involves hierarchical complicated events and processes. Multiple studies have revealed the significance of the formation and structure of tumor-induced capillary networks. In this study, a discrete mathematical model of angiogenesis is studied and modified to capture the realistic physics of capillary network formation. Modifications are performed on the mathematical foundations of an existing discrete model of angiogenesis. The main modifications are the imposition of the matrix density effect, implementation of realistic boundary and initial conditions, and improvement of the method of governing equations based on physical observation. Results show that endothelial cells accelerate angiogenesis and capillary formation as they migrate toward the tumor and clearly exhibit the physical concept of haptotactic movement. On the other hand, consideration of blood flow-induced stress leads to a dynamic adaptive vascular network of capillaries which intelligibly reflects the brush border effect . The present modified model of capillary network formation is based on the physical rationale that defines a clear mathematical and physical interpretation of angiogenesis, which is likely to be used in cancer development modeling and anti-angiogenic therapies.
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Affiliation(s)
- M Soltani
- Department of Mechanical Engineering, K. N. Toosi University of Technology, Tehran, Iran.,Department of Electrical and Computer Engineering, University of Waterloo, Waterloo, Ontario, Canada.,Centre for Biotechnology and Bioengineering (CBB), University of Waterloo, Waterloo, Ontario, Canada.,Advanced Bioengineering Initiative Center, Computational Medicine Center, K. N. Toosi University of Technology, Tehran, Tehran Province, Iran
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2
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Wang R, Zhang L, Tang T, Yan F, Jiang D. Effects of SO 2 Pollution on Household Insurance Purchasing in China: A Cross-Sectional Study. Front Public Health 2021; 9:777943. [PMID: 34900918 PMCID: PMC8655105 DOI: 10.3389/fpubh.2021.777943] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Accepted: 10/08/2021] [Indexed: 12/16/2022] Open
Abstract
There have been considerable concerns regarding the effects of air pollution on health and economy over the past decades across the world. As insurance coverage has been closely related to household welfare, we aim to investigate the influence of air pollution, in particular, the sulfur dioxide (SO2) pollution on household purchases of commercial health insurance using data from the 2017 China Household Financial Survey (CHFS). The results show that the rise in SO2 emission has a significant positive association with tendency of residents to participate in commercial health insurance. The possibility of household commercial health insurance purchasing increases by 4% per 1,000 tons of SO2 emission. In addition, the proportion of commercial health insurance expenditure in household annual income increases by 29% per 1,000 tons of SO2 emission. The effects are also found to differ among resident groups. Residents in eastern parts of China are more likely to buy commercial health insurance facing SO2 pollution compared to those in western parts of China; people with higher income are more likely to be affected compared to those with lower income; families with the household head being female are more likely to be affected compared to those with the household head being male. This research provides baseline information on the formulation and implementation of future operation strategy in commercial health insurance companies of China.
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Affiliation(s)
- Ren Wang
- School of Finance, Hunan University of Technology and Business, Changsha, China
| | - Lizhi Zhang
- School of Finance, Hunan University of Technology and Business, Changsha, China
| | - Ting Tang
- College of Science, Hunan University of Technology and Business, Changsha, China
| | - Fei Yan
- School of Finance, Hunan University of Technology and Business, Changsha, China
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3
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Murphy RJ, Buenzli PR, Tambyah TA, Thompson EW, Hugo HJ, Baker RE, Simpson MJ. The role of mechanical interactions in EMT. Phys Biol 2021; 18. [PMID: 33789261 DOI: 10.1088/1478-3975/abf425] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2020] [Accepted: 03/31/2021] [Indexed: 02/07/2023]
Abstract
The detachment of cells from the boundary of an epithelial tissue and the subsequent invasion of these cells into surrounding tissues is important for cancer development and wound healing, and is strongly associated with the epithelial-mesenchymal transition (EMT). Chemical signals, such as TGF-β, produced by surrounding tissue can be uptaken by cells and induce EMT. In this work, we present a novel cell-based discrete mathematical model of mechanical cellular relaxation, cell proliferation, and cell detachment driven by chemically-dependent EMT in an epithelial tissue. A continuum description of the model is then derived in the form of a novel nonlinear free boundary problem. Using the discrete and continuum models we explore how the coupling of chemical transport and mechanical interactions influences EMT, and postulate how this could be used to help control EMT in pathological situations.
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Affiliation(s)
- Ryan J Murphy
- Queensland University of Technology, Mathematical Sciences, Brisbane, Australia
| | - Pascal R Buenzli
- Queensland University of Technology, Mathematical Sciences, Brisbane, Australia
| | - Tamara A Tambyah
- Queensland University of Technology, Mathematical Sciences, Brisbane, Australia
| | - Erik W Thompson
- Queensland University of Technology, Institute of Health and Biomedical Innovation, Brisbane, Australia.,Queensland University of Technology, School of Biomedical Sciences, Faculty of Health, Brisbane, Australia.,Translational Research Institute, Brisbane, Australia
| | - Honor J Hugo
- Queensland University of Technology, Institute of Health and Biomedical Innovation, Brisbane, Australia.,Queensland University of Technology, School of Biomedical Sciences, Faculty of Health, Brisbane, Australia.,Translational Research Institute, Brisbane, Australia
| | - Ruth E Baker
- University of Oxford, Mathematical Institute, Oxford, United Kingdom
| | - Matthew J Simpson
- Queensland University of Technology, Mathematical Sciences, Brisbane, Australia
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Gonzalez JM, Puerta-Fernández E, Santana MM, Rekadwad B. On a Non-Discrete Concept of Prokaryotic Species. Microorganisms 2020; 8:microorganisms8111723. [PMID: 33158054 PMCID: PMC7692863 DOI: 10.3390/microorganisms8111723] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 11/02/2020] [Accepted: 11/03/2020] [Indexed: 01/09/2023] Open
Abstract
The taxonomic concept of species has received continuous attention. A microbial species as a discrete box contains a limited number of highly similar microorganisms assigned to that taxon, following a polyphasic approach. In the 21st Century, with the advancements of sequencing technologies and genomics, the existence of a huge prokaryotic diversity has become well known. At present, the prokaryotic species might no longer have to be understood as discrete values (such as 1 or 2, by homology to Natural numbers); rather, it is expected that some microorganisms could be potentially distributed (according to their genome features and phenotypes) in between others (such as decimal numbers between 1 and 2; real numbers). We propose a continuous species concept for microorganisms, which adapts to the current knowledge on the huge diversity, variability and heterogeneity existing among bacteria and archaea. Likely, this concept could be extended to eukaryotic microorganisms. The continuous species concept considers a species to be delimited by the distance between a range of variable features following a Gaussian-type distribution around a reference organism (i.e., its type strain). Some potential pros and cons of a continuous concept are commented on, offering novel perspectives on our understanding of the highly diversified prokaryotic world, thus promoting discussion and further investigation in the field.
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Affiliation(s)
- Juan M. Gonzalez
- Instituto de Recursos Naturales y Agrobiología, Consejo Superior de Investigaciones Científicas, IRNAS-CSIC, Avda. Reina Mercedes 10, 41012 Sevilla, Spain;
- Correspondence: ; Tel.: +34-95-462-4711
| | - Elena Puerta-Fernández
- Instituto de Recursos Naturales y Agrobiología, Consejo Superior de Investigaciones Científicas, IRNAS-CSIC, Avda. Reina Mercedes 10, 41012 Sevilla, Spain;
| | - Margarida M. Santana
- Centre for Ecology, Evolution and Environmental Changes (cE3c), Faculdade de Ciências da Universidade de Lisboa, Edifício C2, Campo Grande, 1749-016 Lisboa, Portugal;
| | - Bhagwan Rekadwad
- National Centre for Microbial Resource, National Centre for Cell Science, NCCS Complex, Savitribai Phule Pune University Campus, Ganeshkhind Road, Maharashtra State, Pune 411007, India;
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Murphy RJ, Buenzli PR, Baker RE, Simpson MJ. A one-dimensional individual-based mechanical model of cell movement in heterogeneous tissues and its coarse-grained approximation. Proc Math Phys Eng Sci 2019; 475:20180838. [PMID: 31423086 PMCID: PMC6694308 DOI: 10.1098/rspa.2018.0838] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Accepted: 06/14/2019] [Indexed: 12/21/2022] Open
Abstract
Mechanical heterogeneity in biological tissues, in particular stiffness, can be used to distinguish between healthy and diseased states. However, it is often difficult to explore relationships between cellular-level properties and tissue-level outcomes when biological experiments are performed at a single scale only. To overcome this difficulty, we develop a multi-scale mathematical model which provides a clear framework to explore these connections across biological scales. Starting with an individual-based mechanical model of cell movement, we subsequently derive a novel coarse-grained system of partial differential equations governing the evolution of the cell density due to heterogeneous cellular properties. We demonstrate that solutions of the individual-based model converge to numerical solutions of the coarse-grained model, for both slowly-varying-in-space and rapidly-varying-in-space cellular properties. We discuss applications of the model, such as determining relative cellular-level properties and an interpretation of data from a breast cancer detection experiment.
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Affiliation(s)
- R. J. Murphy
- Mathematical Sciences, Queensland University of Technology, Brisbane, Australia
| | - P. R. Buenzli
- Mathematical Sciences, Queensland University of Technology, Brisbane, Australia
| | - R. E. Baker
- Mathematical Institute, University of Oxford, Oxford, UK
| | - M. J. Simpson
- Mathematical Sciences, Queensland University of Technology, Brisbane, Australia
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Salgia R, Mambetsariev I, Hewelt B, Achuthan S, Li H, Poroyko V, Wang Y, Sattler M. Modeling small cell lung cancer (SCLC) biology through deterministic and stochastic mathematical models. Oncotarget 2018; 9:26226-26242. [PMID: 29899855 PMCID: PMC5995226 DOI: 10.18632/oncotarget.25360] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Accepted: 04/24/2018] [Indexed: 12/14/2022] Open
Abstract
Mathematical cancer models are immensely powerful tools that are based in part on the fractal nature of biological structures, such as the geometry of the lung. Cancers of the lung provide an opportune model to develop and apply algorithms that capture changes and disease phenotypes. We reviewed mathematical models that have been developed for biological sciences and applied them in the context of small cell lung cancer (SCLC) growth, mutational heterogeneity, and mechanisms of metastasis. The ultimate goal is to develop the stochastic and deterministic nature of this disease, to link this comprehensive set of tools back to its fractalness and to provide a platform for accurate biomarker development. These techniques may be particularly useful in the context of drug development research, such as combination with existing omics approaches. The integration of these tools will be important to further understand the biology of SCLC and ultimately develop novel therapeutics.
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Affiliation(s)
- Ravi Salgia
- City of Hope, Department of Medical Oncology and Therapeutics Research, Duarte 91010, CA, USA
| | - Isa Mambetsariev
- City of Hope, Department of Medical Oncology and Therapeutics Research, Duarte 91010, CA, USA
| | - Blake Hewelt
- City of Hope, Department of Medical Oncology and Therapeutics Research, Duarte 91010, CA, USA
| | | | - Haiqing Li
- City of Hope, Center for Informatics, Duarte 91010, CA, USA
| | - Valeriy Poroyko
- City of Hope, Department of Medical Oncology and Therapeutics Research, Duarte 91010, CA, USA
| | - Yingyu Wang
- City of Hope, Center for Informatics, Duarte 91010, CA, USA
| | - Martin Sattler
- Dana-Farber Cancer Institute, Department of Medical Oncology, Boston 02215, MA, USA.,Harvard Medical School, Department of Medicine, Boston 02115, MA, USA
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Abstract
The paper studies systems of rigid bodies with randomly generated geometry interconnected by normal and tangential bonds. The stiffness of these bonds determines the macroscopic elastic modulus while the macroscopic Poisson’s ratio of the system is determined solely by the normal/tangential stiffness ratio. Discrete models with no directional bias have the same probability of element orientation for any direction and therefore the same mechanical properties in a statistical sense at any point and direction. However, the layers of elements in the vicinity of the boundary exhibit biased orientation, preferring elements parallel with the boundary. As a consequence, when strain occurs in this direction, the boundary layer becomes stiffer than the interior for the normal/tangential stiffness ratio larger than one, and vice versa. Nonlinear constitutive laws are typically such that the straining of an element in shear results in higher strength and ductility than straining in tension. Since the boundary layer tends, due to the bias in the elemental orientation, to involve more tension than shear at the contacts, it also becomes weaker and less ductile. The paper documents these observations and compares them to the results of theoretical analysis.
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Affiliation(s)
- Jan Eliáš
- Brno University of Technology, Faculty of Civil Engineering, Veverˇí 331/95, Brno 60200, Czech Republic.
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Abstract
Recently, the description of immune response by discrete models has emerged to play an important role to study the problems in the area of human immunodeficiency virus type 1 (HIV-1) infection, leading to AIDS. As infection of target immune cells by HIV-1 mainly takes place in the lymphoid tissue, cellular automata (CA) models thus represent a significant step in understanding when the infected population is dispersed. Motivated by these, the studies of the dynamics of HIV-1 infection using CA in memory have been presented to recognize how CA have been developed for HIV-1 dynamics, which issues have been studied already and which issues still are objectives in future studies.
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Affiliation(s)
- Monamorn Precharattana
- 1 Institute for Innovative Learning, Mahidol University, 999 Salaya, Phutthamonthon District Nakhon Pathom 73170, Thailand
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He W, Tang Y, Qi B, Lu C, Qin C, Wei Y, Yi J, Chen M. Phylogenetic analysis and positive-selection site detecting of vascular endothelial growth factor family in vertebrates. Gene 2013; 535:345-52. [PMID: 24200960 DOI: 10.1016/j.gene.2013.10.031] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2013] [Accepted: 10/12/2013] [Indexed: 11/28/2022]
Abstract
Vascular endothelial growth factor (VEGF), known to play an important role in vascular homeostasis, vascular integrity and angiogenesis, is little known about the evolutionary relationship of its five members especially the role of gene duplication and natural selection in the evolution of the VEGF family. In this study, seventy-five full-length cDNA sequences from 33 vertebrate species were extracted from the NCBI's GenBank, UniProt protein database and the Ensembl database. By phylogenetic analyses, we investigated the origin, conservation, and evolution of the VEGFs. Five VEGF family members in vertebrates might be formed by gene duplication. The inferred evolutionary transitions that separate members which belong to different gene clusters correlated with changes in functional properties. Selection analysis and protein structure analysis were combined to explain the relationship of the site-specific evolution in the vertebrate VEGF family. Eleven positive selection sites, one transmembrane region and the active sites were detected in this process.
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Affiliation(s)
- Wenwu He
- Department of Cardiothoracic Surgery, First Affiliated Hospital, Guangxi Medical University, Nanning, Guangxi, China; Department of Cardiothoracic Surgery, Nanchong Central Hospital, The Second Clinical College of North Sichuan Medical college, Nanchong, Sichuan, PR China
| | - Yanyan Tang
- Department of Neurology, First Affiliated Hospital, Guangxi Medical University, Nanning, Guangxi, China
| | - Bin Qi
- Department of Neurology, First Affiliated Hospital, Guangxi Medical University, Nanning, Guangxi, China
| | - Chuansen Lu
- Department of Neurology, First Affiliated Hospital, Guangxi Medical University, Nanning, Guangxi, China
| | - Chao Qin
- Department of Neurology, First Affiliated Hospital, Guangxi Medical University, Nanning, Guangxi, China
| | - Yunfei Wei
- Department of Neurology, First Affiliated Hospital, Guangxi Medical University, Nanning, Guangxi, China
| | - Jiachao Yi
- Department of Neurology, Liugang Hospital, Liuzhou, Guangxi, China
| | - Mingwu Chen
- Department of Cardiothoracic Surgery, First Affiliated Hospital, Guangxi Medical University, Nanning, Guangxi, China.
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Ferguson JC, Tarara JM, Mills LJ, Grove GG, Keller M. Dynamic thermal time model of cold hardiness for dormant grapevine buds. Ann Bot 2011; 107:389-96. [PMID: 21212090 PMCID: PMC3043938 DOI: 10.1093/aob/mcq263] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2010] [Revised: 11/15/2010] [Accepted: 11/26/2010] [Indexed: 05/22/2023]
Abstract
BACKGROUND AND AIMS Grapevine (Vitis spp.) cold hardiness varies dynamically throughout the dormant season, primarily in response to changes in temperature. The development and possible uses of a discrete-dynamic model of bud cold hardiness for three Vitis genotypes are described. METHODS Iterative methods were used to optimize and evaluate model parameters by minimizing the root mean square error between observed and predicted bud hardiness, using up to 22 years of low-temperature exotherm data. Three grape cultivars were studied: Cabernet Sauvignon, Chardonnay (both V. vinifera) and Concord (V. labruscana). The model uses time steps of 1 d along with the measured daily mean air temperature to calculate the change in bud hardiness, which is then added to the hardiness from the previous day. Cultivar-dependent thermal time thresholds determine whether buds acclimate (gain hardiness) or deacclimate (lose hardiness). KEY RESULTS The parameterized model predicted bud hardiness for Cabernet Sauvignon and Chardonnay with an r(2) = 0·89 and for Concord with an r(2) = 0·82. Thermal time thresholds and (de-)acclimation rates changed between the early and late dormant season and were cultivar dependent but independent of each other. The timing of these changes was also unique for each cultivar. Concord achieved the greatest mid-winter hardiness but had the highest deacclimation rate, which resulted in rapid loss of hardiness in spring. Cabernet Sauvignon was least hardy, yet maintained its hardiness latest as a result of late transition to eco-dormancy, a high threshold temperature required to induce deacclimation and a low deacclimation rate. CONCLUSIONS A robust model of grapevine bud cold hardiness was developed that will aid in the anticipation of and response to potential injury from fluctuations in winter temperature and from extreme cold events. The model parameters that produce the best fit also permit insight into dynamic differences in hardiness among genotypes.
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Affiliation(s)
- John C. Ferguson
- Department of Horticulture and Landscape Architecture, Irrigated Agriculture Research and Extension Center, Washington State University, Prosser, WA 99350, USA
| | - Julie M. Tarara
- Horticultural Crops Research Unit, United States Department of Agriculture, Agricultural Research Service, Prosser, WA 99350, USA
| | - Lynn J. Mills
- Department of Horticulture and Landscape Architecture, Irrigated Agriculture Research and Extension Center, Washington State University, Prosser, WA 99350, USA
| | - Gary G. Grove
- Department of Plant Pathology, Irrigated Agriculture Research and Extension Center, Washington State University, Prosser, WA 99350, USA
| | - Markus Keller
- Department of Horticulture and Landscape Architecture, Irrigated Agriculture Research and Extension Center, Washington State University, Prosser, WA 99350, USA
- For correspondence. E-mail
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