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Mathematical modelling

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https://www.readbyqxmd.com/read/27933657/analysis-of-temozolomide-resistance-in-low-grade-gliomas-by-using-a-mechanistic-mathematical-model
#1
Edouard Ollier, Pauline Mazzocco, Damien Ricard, Gentian Kaloshi, Ahmed Idbaih, Agusti Alentorn, Dimitri Psimaras, Jérôme Honnorat, Jean-Yves Delattre, Emmanuel Grenier, François Ducray, Adeline Samson
Understanding how tumours develop resistance to chemotherapy is a major issue in oncology. When treated with temozolomide (TMZ), an oral alkylating chemotherapy drug, most low-grade gliomas (LGG) show an initial volume decrease but this effect is rarely long lasting. In addition, it has been suggested that TMZ may drive tumour progression in a subset of patients as a result of acquired resistance. Using longitudinal tumour size measurements from 121 patients, the aim of the present study was to develop a semi-mechanistic mathematical model to determine whether resistance of LGG to TMZ was more likely to result from primary and/or from chemotherapy-induced acquired resistance that may contribute to tumour progression...
December 9, 2016: Fundamental & Clinical Pharmacology
https://www.readbyqxmd.com/read/27933039/the-contribution-of-mathematical-modeling-to-understanding-dynamic-aspects-of-rumen-metabolism
#2
André Bannink, Henk J van Lingen, Jennifer L Ellis, James France, Jan Dijkstra
All mechanistic rumen models cover the main drivers of variation in rumen function, which are feed intake, the differences between feedstuffs and feeds in their intrinsic rumen degradation characteristics, and fractional outflow rate of fluid and particulate matter. Dynamic modeling approaches are best suited to the prediction of more nuanced responses in rumen metabolism, and represent the dynamics of the interactions between substrates and micro-organisms and inter-microbial interactions. The concepts of dynamics are discussed for the case of rumen starch digestion as influenced by starch intake rate and frequency of feed intake, and for the case of fermentation of fiber in the large intestine...
2016: Frontiers in Microbiology
https://www.readbyqxmd.com/read/27933004/policy-implications-of-achievement-testing-using-multilevel-models-the-case-of-brazilian-elementary-schools
#3
Igor G Menezes, Victor R Duran, Euclides J Mendonça Filho, Tainã J Veloso, Stella M S Sarmento, Christine L Paget, Kai Ruggeri
Large-scale educational assessment has been established as source of descriptive, evaluative and interpretative information that influence educational policies worldwide throughout the last third of the twentieth century. In the 1990s the Brazilian Ministry of Education developed the National Basic Education Assessment System (SAEB) that regularly measures management, resource and contextual school features and academic achievement in public and private institutions. In 2005, after significant piloting and review of the SAEB, a new sampling strategy was taken and Prova Brasil became the new instrument used by the Ministry to assess skills in Portuguese (reading comprehension) and Mathematics (problem solving), as well as collecting contextual information concerning the school, principal, teacher, and the students...
2016: Frontiers in Psychology
https://www.readbyqxmd.com/read/27932970/bayesian-inference-of-synaptic-quantal-parameters-from-correlated-vesicle-release
#4
Alex D Bird, Mark J Wall, Magnus J E Richardson
Synaptic transmission is both history-dependent and stochastic, resulting in varying responses to presentations of the same presynaptic stimulus. This complicates attempts to infer synaptic parameters and has led to the proposal of a number of different strategies for their quantification. Recently Bayesian approaches have been applied to make more efficient use of the data collected in paired intracellular recordings. Methods have been developed that either provide a complete model of the distribution of amplitudes for isolated responses or approximate the amplitude distributions of a train of post-synaptic potentials, with correct short-term synaptic dynamics but neglecting correlations...
2016: Frontiers in Computational Neuroscience
https://www.readbyqxmd.com/read/27932782/cdc-grand-rounds-modeling-and-public-health-decision-making
#5
Leah S Fischer, Scott Santibanez, Richard J Hatchett, Daniel B Jernigan, Lauren Ancel Meyers, Phoebe G Thorpe, Martin I Meltzer
Mathematical models incorporate various data sources and advanced computational techniques to portray real-world disease transmission and translate the basic science of infectious diseases into decision-support tools for public health. Unlike standard epidemiologic methods that rely on complete data, modeling is needed when there are gaps in data. By combining diverse data sources, models can fill gaps when critical decisions must be made using incomplete or limited information. They can be used to assess the effect and feasibility of different scenarios and provide insight into the emergence, spread, and control of disease...
December 9, 2016: MMWR. Morbidity and Mortality Weekly Report
https://www.readbyqxmd.com/read/27932685/longitudinal-micro-computed-tomography-monitoring-of-progressive-liver-regeneration-in-a-mouse-model-of-partial-hepatectomy
#6
Olga M Will, Timo Damm, Graeme M Campbell, Witigo von Schönfells, Yahya Açil, Marcus Will, Athena Chalaris-Rissmann, Mustafa Ayna, Claudia Drucker, Claus-Christian Glüer
The partial hepatectomy (PH) model is widely used to study liver regeneration. Currently, the extent of regeneration is analyzed by measuring the weight of the liver post-mortem or by magnetic resonance imaging. In this study we aimed to determine whether liver volume gain can be accurately measured using micro-computed tomography (microCT). Approximately 42% of the liver was removed by ligation in C57BL/6 N mice. Mice were divided into two study groups. In group 1 conventional characterization of liver hyperplasia was performed by weighing the liver post-mortem...
December 8, 2016: Laboratory Animals
https://www.readbyqxmd.com/read/27932632/not-by-success-alone-role-models-provide-pathways-to-communal-opportunities-in-stem
#7
Melissa A Fuesting, Amanda B Diekman
Because of stereotypes that science, technology, engineering, and mathematics (STEM) fields do not fulfill communal goals, communally oriented individuals may select out of STEM. One potential route to engaging and promoting communally oriented individuals in STEM fields is through interactions with advisors or role models in STEM. We first demonstrate the perceived difficulty of finding role models who enact communal behaviors in STEM relative to other fields (Preliminary Study). Communally oriented students reported higher likelihood of observing admired others in math or science (i...
December 8, 2016: Personality & Social Psychology Bulletin
https://www.readbyqxmd.com/read/27932503/computational-modelling-of-epithelial-fluid-and-ion-transport-in-the-parotid-duct-after-transfection-of-human-aquaporin-1
#8
Shelley Fong, John A Chiorini, James Sneyd, Vinod Suresh
Previous studies have shown that localized delivery of the aquaporin-1 (AQP1) gene to the parotid duct can restore saliva flow in minipigs following irradiation-induced salivary hypofunction. The resulting flow rate and electrochemisty of secreted saliva contradicts current understanding of ductal fluid transport. We hypothesized that changes in expression of ion transport proteins have occurred following AQP1 transfection. We use a mathematical model of ion and fluid transport across the parotid duct epithelial cells to predict the expression profile of ion transporters that are consistent with the experimental measurements of saliva composition and secretion rates...
December 8, 2016: American Journal of Physiology. Gastrointestinal and Liver Physiology
https://www.readbyqxmd.com/read/27932443/pd-l1-blockade-enhances-response-of-pancreatic-ductal-adenocarcinoma-to-radiotherapy
#9
Abul Azad, Su Yin Lim, Zenobia D'Costa, Keaton Jones, Angela Diana, Owen J Sansom, Philipp Kruger, Stanley Liu, W Gillies McKenna, Omer Dushek, Ruth J Muschel, Emmanouil Fokas
Pancreatic ductal adenocarcinoma (PDAC) is considered a non-immunogenic tumor, and immune checkpoint inhibitor monotherapy lacks efficacy in this disease. Radiotherapy (RT) can stimulate the immune system. Here, we show that treatment of KPC and Pan02 murine PDAC cells with RT and gemcitabine upregulated PD-L1 expression in a JAK/Stat1-dependent manner. In vitro, PD-L1 inhibition did not alter radio- and chemosensitivity. In vivo, addition of anti-PD-L1 to high (12, 5 × 3, 20 Gy) but not low (6, 5 × 2 Gy) RT doses significantly improved tumor response in KPC and Pan02 allografts...
December 8, 2016: EMBO Molecular Medicine
https://www.readbyqxmd.com/read/27932298/modeling-birds-on-wires
#10
A Aydoğdu, P Frasca, C D'Apice, R Manzo, J M Thornton, B Gachomo, T Wilson, B Cheung, U Tariq, W Saidel, B Piccoli
In this paper we introduce a mathematical model to study the group dynamics of birds resting on wires. The model is agent-based and postulates attraction-repulsion forces between the interacting birds: the interactions are "topological", in the sense that they involve a given number of neighbors irrespective of their distance. The model is first mathematically analyzed and then simulated to study its main properties: we observe that the model predicts birds to be more widely spaced near the borders of each group...
December 5, 2016: Journal of Theoretical Biology
https://www.readbyqxmd.com/read/27931974/mathematical-modeling-of-atopic-dermatitis-reveals-double-switch-mechanisms-underlying-four-common-disease-phenotypes
#11
Elisa Domínguez-Hüttinger, Panayiotis Christodoulides, Kosuke Miyauchi, Alan D Irvine, Mariko Okada-Hatakeyama, Masato Kubo, Reiko J Tanaka
BACKGROUND: The skin barrier acts as the first line of defense against constant exposure to biological, microbial, physical and chemical environmental stressors. Dynamic interplay between defects in the skin barrier, dysfunctional immune responses, and environmental stressors are major factors in the development of atopic dermatitis (AD). A systems-biology modeling approach can yield significant insights into these complex and dynamic processes through integration of prior biological data...
December 5, 2016: Journal of Allergy and Clinical Immunology
https://www.readbyqxmd.com/read/27931676/passive-case-finding-for-tuberculosis-is-not-enough
#12
REVIEW
Jennifer Ho, Greg J Fox, Ben J Marais
Current World Health Organisation targets calling for an end to the global tuberculosis (TB) epidemic by 2035 require a dramatic improvement in current case-detection strategies. A reliance on passive case finding (PCF) has resulted consistently, in over three million infectious TB cases per year, being missed by the health system, leading to ongoing transmission of infection within families and communities. Active case finding (ACF) for TB has been recognized as an important complementary strategy to PCF, in order to diagnose and treat patients earlier, reducing the period of infectiousness and therefore transmission...
December 2016: International Journal of Mycobacteriology
https://www.readbyqxmd.com/read/27931238/elaboration-of-a-nomogram-to-predict-nonsentinel-node-status-in-breast-cancer-patients-with-positive-sentinel-node-intraoperatively-assessed-with-one-step-nucleic-amplification-retrospective-and-validation-phase
#13
Franco Di Filippo, Simona Di Filippo, Anna Maria Ferrari, Raffaele Antonetti, Alessandro Battaglia, Francesca Becherini, Laia Bernet, Renzo Boldorini, Catherine Bouteille, Simonetta Buglioni, Paolo Burelli, Rafael Cano, Vincenzo Canzonieri, Pierluigi Chiodera, Alfredo Cirilli, Luigi Coppola, Stefano Drago, Luca Di Tommaso, Privato Fenaroli, Roberto Franchini, Andrea Gianatti, Diana Giannarelli, Carmela Giardina, Florence Godey, Massimo M Grassi, Giuseppe B Grassi, Siobhan Laws, Samuele Massarut, Giuseppe Naccarato, Maria Iole Natalicchio, Sergio Orefice, Fabrizio Palmieri, Tiziana Perin, Manuela Roncella, Massimo G Roncalli, Antonio Rulli, Angelo Sidoni, Corrado Tinterri, Maria C Truglia, Isabella Sperduti
BACKGROUND: Tumor-positive sentinel lymph node (SLN) biopsy results in a risk of non sentinel node metastases in micro- and macro-metastases ranging from 20 to 50%, respectively. Therefore, most patients underwent unnecessary axillary lymph node dissections. We have previously developed a mathematical model for predicting patient-specific risk of non sentinel node (NSN) metastases based on 2460 patients. The study reports the results of the validation phase where a total of 1945 patients were enrolled, aimed at identifying a tool that gives the possibility to the surgeon to choose intraoperatively whether to perform or not axillary lymph node dissection (ALND)...
December 8, 2016: Journal of Experimental & Clinical Cancer Research: CR
https://www.readbyqxmd.com/read/27930659/bee-inspired-novel-optimization-algorithm-and-mathematical-model-for-effective-and-efficient-route-planning-in-railway-system
#14
Kah Huo Leong, Hamzah Abdul-Rahman, Chen Wang, Chiu Chuen Onn, Siaw-Chuing Loo
Railway and metro transport systems (RS) are becoming one of the popular choices of transportation among people, especially those who live in urban cities. Urbanization and increasing population due to rapid development of economy in many cities are leading to a bigger demand for urban rail transit. Despite being a popular variant of Traveling Salesman Problem (TSP), it appears that the universal formula or techniques to solve the problem are yet to be found. This paper aims to develop an optimization algorithm for optimum route selection to multiple destinations in RS before returning to the starting point...
2016: PloS One
https://www.readbyqxmd.com/read/27930563/combining-ultrasonography-and-noncontrast-helical-computerized-tomography-to-evaluate-holmium-laser-lithotripsy
#15
Jia Mi, Jie Li, Qinglu Zhang, Xing Wang, Hongyu Liu, Yanlu Cao, Xiaoyan Liu, Xiao Sun, Mengmeng Shang, Qing Liu
The purpose of the study was to establish a mathematical model for correlating the combination of ultrasonography and noncontrast helical computerized tomography (NCHCT) with the total energy of Holmium laser lithotripsy.In this study, from March 2013 to February 2014, 180 patients with single urinary calculus were examined using ultrasonography and NCHCT before Holmium laser lithotripsy. The calculus location and size, acoustic shadowing (AS) level, twinkling artifact intensity (TAI), and CT value were all documented...
December 2016: Medicine (Baltimore)
https://www.readbyqxmd.com/read/27930555/establishment-of-the-intracranial-hemodynamic-model-based-on-contrast-medium-and-clinical-applications
#16
Yaoer Cheng, Wen He
Ischemic cerebrovascular diseases are one of the most common vascular diseases in aged people and CT perfusion (CTP) is a very popular tool to detect the ischemic changes in brain vascular. The present study aims to establish a novel intracranial hemodynamic model to simulate anterior cerebral artery blood flow, and compare the actual and simulated hemodynamic parameters of healthy people and patients with carotid stenosis or occlusion.A mathematical model of the intracranial hemodynamic was generated using MATLAB software, and data from patients with or without infarct disease (57 and 44 cases, respectively) were retrospectively collected to test the new model...
December 2016: Medicine (Baltimore)
https://www.readbyqxmd.com/read/27930361/determining-the-appropriate-model-complexity-for-patient-specific-advice-on-mechanical-ventilation
#17
Stephen E Rees, Dan S Karbing
Mathematical physiological models can be applied in medical decision support systems. To do so requires consideration of the necessary model complexity. Models that simulate changes in the individual patient are required, meaning that models should have a complexity where parameters can be uniquely identified at the bedside from clinical data and where the models adequately represent the individual patient's (patho)physiology. This paper describes the models included in a system for providing decision support for mechanical ventilation...
December 8, 2016: Biomedizinische Technik. Biomedical Engineering
https://www.readbyqxmd.com/read/27930310/cliff-edge-model-of-obstetric-selection-in-humans
#18
Philipp Mitteroecker, Simon M Huttegger, Barbara Fischer, Mihaela Pavlicev
The strikingly high incidence of obstructed labor due to the disproportion of fetal size and the mother's pelvic dimensions has puzzled evolutionary scientists for decades. Here we propose that these high rates are a direct consequence of the distinct characteristics of human obstetric selection. Neonatal size relative to the birth-relevant maternal dimensions is highly variable and positively associated with reproductive success until it reaches a critical value, beyond which natural delivery becomes impossible...
December 5, 2016: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/27928586/physicochemical-mechanisms-of-stone-formation
#19
REVIEW
Allen L Rodgers
In this article, the term "physicochemical mechanism" is defined as a sequential series of steps culminating in the formation of a renal stone. Distinctions are drawn between physicochemical prerequisites for urinary supersaturation, crystallization, and stone formation. In particular, attention is focussed on the transition from crystal to stone. Emphasis is laid on crystal retention being the fundamental mechanism by which stones are formed, and mention is made of the different ways in which it can be achieved...
December 7, 2016: Urolithiasis
https://www.readbyqxmd.com/read/27927902/challenges-in-species-tree-estimation-under-the-multispecies-coalescent-model
#20
REVIEW
Bo Xu, Ziheng Yang
The multispecies coalescent (MSC) model has emerged as a powerful framework for inferring species phylogenies while accounting for ancestral polymorphism and gene tree-species tree conflict. A number of methods have been developed in the past few years to estimate the species tree under the MSC. The full likelihood methods (including maximum likelihood and Bayesian inference) average over the unknown gene trees and accommodate their uncertainties properly but involve intensive computation. The approximate or summary coalescent methods are computationally fast and are applicable to genomic datasets with thousands of loci, but do not make an efficient use of information in the multilocus data...
December 2016: Genetics
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