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mathematical modeling

Christophe Praud, Karine Vauchez, Pascal Zongo, Jean-Thomas Vilquin
Cell transplantation has been challenged in several clinical indications of genetic or acquired muscular diseases, but therapeutic success were mitigated. To understand and improve the yields of tissue regeneration, we aimed at modelling the fate of CD56-positive human myoblasts after transplantation. Using immunodeficient severe combined immunodeficiency (SCID) mice as recipients, we assessed the survival, integration and satellite cell niche occupancy of human myoblasts by a triple immunohistochemical labelling of laminin, dystrophin and human lamin A/C...
February 16, 2018: Experimental Cell Research
Xiao Zhu, David B Finlay, Michelle Glass, Stephen B Duffull
BACKGROUND AND PURPOSE: Functional selectivity describes the ability of ligands to differentially regulate multiple signalling pathways when coupled to a single receptor and the operational model is commonly used to analyse these data. Here, we assess the mathematical properties of the operational model and evaluate the impact of fixing parameters on model performance. EXPERIMENTAL APPROACH: The operational model was evaluated using both a mathematical identifiability analysis and simulation...
February 19, 2018: British Journal of Pharmacology
Andreas Focks, Francesca Grisoni, Alpar Barsi, Marco Vighi
In the last decades, modelling approaches in the context of environmental risk assessment for chemicals have been under the spotlight of researchers in academia, regulatory bodies and industry. This is because mathematical and simulation models allow to gain deeper mechanistic understanding of fate and effect processes of organic contaminants in the environment. In addition, models make it possible to predict the toxic effects of compounds along with other relevant properties, such as biodegradability, uptake and bioaccumulation...
February 19, 2018: Integrated Environmental Assessment and Management
Beth McMillan, David J Gavaghan, Gary R Mirams
Drug-induced Torsades de Pointes (TdP) arrhythmia is of major interest in predictive toxicology. Drugs which cause TdP block the hERG cardiac potassium channel. However, not all drugs that block hERG cause TdP. As such, further understanding of the mechanistic route to TdP is needed. Early afterdepolarisations (EADs) are a cell-level phenomenon in which the membrane of a cardiac cell depolarises a second time before repolarisation, and EADs are seen in hearts during TdP. Therefore, we propose a method of predicting TdP using induced EADs combined with multiple ion channel block in simulations using biophysically-based mathematical models of human ventricular cell electrophysiology...
November 1, 2017: Toxicology Research
Felix Carbonell, Yasser Iturria-Medina, Alan C Evans
Protein misfolding refers to a process where proteins become structurally abnormal and lose their specific 3-dimensional spatial configuration. The histopathological presence of misfolded protein (MP) aggregates has been associated as the primary evidence of multiple neurological diseases, including Prion diseases, Alzheimer's disease, Parkinson's disease, and Creutzfeldt-Jacob disease. However, the exact mechanisms of MP aggregation and propagation, as well as their impact in the long-term patient's clinical condition are still not well understood...
2018: Frontiers in Neurology
Aida Kesraoui, Sarra Bouzaabia, Mongi Seffen
The present investigation aims to prepare a hybrid material from Luffa cylindrica and metal oxides (ZnO, Al2 O3 ) by precipitation for different percentages of zinc and aluminum (1, 2, and 4%) with a determined amount of biomass (a diameter of 250 μm). Physicochemical characterization of "Luffa cylindrica" and "Luffa cylindrica-metal oxides" was carried out by Boehm titration, pHPZC determination, scanning electron microscopy (SEM), and FTIR spectroscopic analysis. The process was optimized according to the adsorbed amount of methylene blue: MB (cationic dye) and methyl orange: MO (anionic dye) onto Luffa cylindrica and hybrid materials prepared...
February 18, 2018: Environmental Science and Pollution Research International
Jin Park, Marta Dies, Yihan Lin, Sahand Hormoz, Stephanie E Smith-Unna, Sofia Quinodoz, María Jesús Hernández-Jiménez, Jordi Garcia-Ojalvo, James C W Locke, Michael B Elowitz
In cells, specific regulators often compete for limited amounts of a core enzymatic resource. It is typically assumed that competition leads to partitioning of core enzyme molecules among regulators at constant levels. Alternatively, however, different regulatory species could time share, or take turns utilizing, the core resource. Using quantitative time-lapse microscopy, we analyzed sigma factor activity dynamics, and their competition for RNA polymerase, in individual Bacillus subtilis cells under energy stress...
January 29, 2018: Cell Systems
Farras Abdelnour, Michael Dayan, Orrin Devinsky, Thomas Thesen, Ashish Raj
How structural connectivity (SC) gives rise to functional connectivity (FC) is not fully understood. Here we mathematically derive a simple relationship between SC measured from diffusion tensor imaging, and FC from resting state fMRI. We establish that SC and FC are related via (structural) Laplacian spectra, whereby FC and SC share eigenvectors and their eigenvalues are exponentially related. This gives, for the first time, a simple and analytical relationship between the graph spectra of structural and functional networks...
February 14, 2018: NeuroImage
Ana Topete, Andreia S Oliveira, A Fernandes, T G Nunes, A P Serro, B Saramago
Although the possibility of using drug-loaded ophthalmic lens to promote sustained drug release has been thoroughly pursued, there are still problems to be solved associated to the different alternatives. In this work, we went back to the traditional method of drug loading by soaking in the drug solution and tried to optimize the release profiles by changing the temperature and the time of loading. Two materials commercially available under the names of CI26Y and Definitive 50 were chosen. CI26Y is used for intraocular lenses (IOLs) and Definitive 50 for soft contact lenses (SCLs)...
February 14, 2018: European Journal of Pharmaceutical Sciences
Gustav Markkula, Erwin Boer, Richard Romano, Natasha Merat
A conceptual and computational framework is proposed for modelling of human sensorimotor control and is exemplified for the sensorimotor task of steering a car. The framework emphasises control intermittency and extends on existing models by suggesting that the nervous system implements intermittent control using a combination of (1) motor primitives, (2) prediction of sensory outcomes of motor actions, and (3) evidence accumulation of prediction errors. It is shown that approximate but useful sensory predictions in the intermittent control context can be constructed without detailed forward models, as a superposition of simple prediction primitives, resembling neurobiologically observed corollary discharges...
February 16, 2018: Biological Cybernetics
E Iboi, K Okuneye, O Sharomi, A B Gumel
Deterministic (ordinary differential equation) models for the transmission dynamics of vector-borne diseases that incorporate disease-induced death in the host(s) population(s) are generally known to exhibit the phenomenon of backward bifurcation (where a stable disease-free equilibrium of the model coexists with a stable endemic equilibrium when the associated reproduction number of the model is less than unity). Further, it is well known that, in these models, the phenomenon of backward bifurcation does not occur when the disease-induced death rate is negligible (e...
February 16, 2018: Bulletin of Mathematical Biology
László Andrássy, Izabella Gomez, Ágnes Horváth, Katalin Gulyás, Zsófia Pethö, Balázs Juhász, Harjit Pal Bhattoa, Zoltan Szekanecz
Bone may be similar to geological formulations in many ways. Therefore, it may be logical to apply laser-based geological techniques in bone research. The mineral and element oxide composition of bioapatite can be estimated by mathematical models. Laser-induced plasma spectrometry (LIPS) has long been used in geology. This method may provide a possibility to determine the composition and concentration of element oxides forming the inorganic part of bones. In this study, we wished to standardize the LIPS technique and use mathematical calculations and models in order to determine CaO distribution and bone homogeneity using bovine shin bone samples...
February 17, 2018: Lasers in Medical Science
Jing-Xin Zhao, Xiu-Yun Su, Zhe Zhao, Ruo-Xiu Xiao, Li-Cheng Zhang, Pei-Fu Tang
AIM: The aim of this study is to demonstrate the varying rules of radiographic angles following varying three-dimensional (3D) orientations and locations of cup using an accurate mathematical model. METHODS: A cone model is established to address the quantitative relationship between the opening circle of cup and its ellipse projection on radiograph. The varying rules of two-dimensional (2D) radiographic anteversion (RA) and inclination (RI) angles can be analyzed...
February 17, 2018: International Orthopaedics
Rajagopal Murugan, Lisa Buchauer, Gianna Triller, Cornelia Kreschel, Giulia Costa, Gemma Pidelaserra Martí, Katharina Imkeller, Christian E Busse, Sumana Chakravarty, B Kim Lee Sim, Stephen L Hoffman, Elena A Levashina, Peter G Kremsner, Benjamin Mordmüller, Thomas Höfer, Hedda Wardemann
Affinity maturation, the clonal selection and expansion of antigen-activated B cells expressing somatically mutated antibody variants that develop during T cell-dependent germinal center reactions, is considered pivotal for efficient development of protective B cell memory responses to infection and vaccination. Repeated antigen exposure promotes affinity maturation but each time also recruits antigen-reactive naïve B cells into the response. Here, we determined the relative impact of affinity maturation versus antigen-mediated clonal selection of naïve B cells to mount potent B cell memory responses in humans after repeated exposure to a complex pathogen, the malaria parasite Plasmodium falciparum (Pf)...
February 16, 2018: Science Immunology
Jerome Wong-Ng, Antonio Celani, Massimo Vergassola
Bacterial chemotaxis is a classical subject: our knowledge of its molecular pathway has grown very detailed, and experimental observations, as well as mathematical models of the dynamics of chemotactic populations, have a history of several decades. This should not lead to the conclusion that only minor details are left to be understood. Indeed, it is believed that bacterial chemotaxis is under selection for efficiency, yet the underlying functional forces remain largely unknown. These aspects are discussed here by the presentation of illustrative examples related to the role of adaptation and signal integration...
February 13, 2018: Current Opinion in Microbiology
T Mee, N F Kirkby, K J Kirkby
Proton beam therapy (PBT) is still relatively new in cancer treatment and the clinical evidence base is relatively sparse. Mathematical modelling offers assistance when selecting patients for PBT and predicting the demand for service. Discrete event simulation, normal tissue complication probability, quality-adjusted life-years and Markov Chain models are all mathematical and statistical modelling techniques currently used but none is dominant. As new evidence and outcome data become available from PBT, comprehensive models will emerge that are less dependent on the specific technologies of radiotherapy planning and delivery...
February 13, 2018: Clinical Oncology: a Journal of the Royal College of Radiologists
Jake P Taylor-King, Etienne Baratchart, Andrew Dhawan, Elizabeth A Coker, Inga Hansine Rye, Hege Russnes, S Jon Chapman, David Basanta, Andriy Marusyk
Intra-tumour phenotypic heterogeneity limits accuracy of clinical diagnostics and hampers the efficiency of anti-cancer therapies. Dealing with this cellular heterogeneity requires adequate understanding of its sources, which is extremely difficult, as phenotypes of tumour cells integrate hardwired (epi)mutational differences with the dynamic responses to microenvironmental cues. The later comes in form of both direct physical interactions, as well as inputs from gradients of secreted signalling molecules. Furthermore, tumour cells can not only receive microenvironmental cues, but also produce them...
February 14, 2018: Mathematical Medicine and Biology: a Journal of the IMA
Jan Werner, Nikolaos Sfakianakis, Alan D Rendall, Eva Maria Griebeler
Ectothermic and endothermic vertebrates differ not only in their source of body temperature (environment vs. metabolism), but also in growth patterns, in timing of sexual maturation within life, and energy intake functions. Here, we present a mathematical model applicable to ectothermic and endothermic vertebrates. It is designed to test whether differences in the timing of sexual maturation within an animal's life (age at which sexual maturity is reached vs. longevity) together with its ontogenetic gain in body mass (growth curve) can predict the energy intake throughout the animal's life (food intake curve) and can explain differences in energy partitioning (between growth, reproduction, heat production and maintenance, with the latter subsuming any other additional task requiring energy) between ectothermic and endothermic vertebrates...
February 13, 2018: Journal of Theoretical Biology
Tuomas Nurmi, Kalle Parvinen, Vesa Selonen
We propose a novel mathematical model for a metapopulation in which dispersal occurs on two levels: juvenile dispersal from the natal site is mandatory but it may take place either locally within the natal patch or globally between patches. Within each patch, individuals live in sites. Each site can be inhabited by at most one individual at a time and it may be of high or low quality. A disperser immigrates into a high-quality site whenever it obtains one, but it immigrates into a low-quality site only with a certain probability that depends on the time within the dispersal season...
February 13, 2018: Journal of Theoretical Biology
Arijit Pal, Amiya Ranjan Bhowmick, Farhana Yeasmin, Sabyasachi Bhattacharya
Growth curve models play an instrumental role to quantify the growth of biological processes and have immense practical applications across disciplines. In the modelling approach, the absolute growth rate and relative growth rate (RGR) are two most commonly used measures of growth rates. RGR is empirically estimated by Fisher (1921) assuming exponential growth between two consecutive time points and remains invariant under any choice of the underlying growth model. In this article, we propose a new measure of RGR, called modified RGR, which is sensitive to the choice of underlying growth law...
February 13, 2018: Journal of Theoretical Biology
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