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https://www.readbyqxmd.com/read/28088672/using-discrete-multi-physics-for-detailed-exploration-of-hydrodynamics-in-an-in-vitro-colon-system
#1
A Alexiadis, K Stamatopoulos, W Wen, H K Batchelor, S Bakalis, M Barigou, M J H Simmons
We developed a mathematical model that describes the motion of viscous fluids in the partially-filled colon caused by the periodic contractions of flexible walls (peristalsis). In-vitro data are used to validate the model. The model is then used to identify two fundamental mechanisms of mass transport: the surfing mode and the pouring mode. The first mechanism is faster, but only involves the surface of the liquid. The second mechanism causes deeper mixing, and appears to be the main transport mechanism. Based on the gained understanding, we propose a series of measures that can improve the reliability of in-vitro models...
January 9, 2017: Computers in Biology and Medicine
https://www.readbyqxmd.com/read/28088332/manipulation-of-tumor-oxygenation-and-radiosensitivity-through-modification-of-cell-respiration-a-critical-review-of-approaches-and-imaging-biomarkers-for-therapeutic-guidance
#2
REVIEW
Bernard Gallez, Marie-Aline Neveu, Pierre Danhier, Bénédicte F Jordan
Tumor hypoxia has long been considered as a detrimental factor for the response to irradiation. In order to improve the sensitivity of tumors cells to radiation therapy, tumor hypoxia may theoretically be alleviated by increasing the oxygen delivery or by decreasing the oxygen consumption by tumor cells. Mathematical modelling suggested that decreasing the oxygen consumption should be more efficient than increasing oxygen delivery in order to alleviate tumor hypoxia. In this paper, we review several promising strategies targeting the mitochondrial respiration for which alleviation of tumor hypoxia and increase in sensitivity to irradiation have been demonstrated...
January 11, 2017: Biochimica et Biophysica Acta
https://www.readbyqxmd.com/read/28088240/feasibility-of-an-altruistic-sperm-donation-program-in-canada-results-from-a-population-based-model
#3
Daria O'Reilly, James M Bowen, Kuhan Perampaladas, Riaz Qureshi, Feng Xie, Edward Hughes
BACKGROUND: Stringent donor-screening criteria and legislation prohibiting payment for donor gametes have contributed to the radical decline of donor insemination (DI) using sperm provided by Canadian men. Thus, many individuals rely on imported sperm. This paper examines the feasibility of an altruistic sperm donation (ASD) program to meet the needs of Canadians. METHODS: Using Canadian census data, published literature and expert opinions, two population-based, top-down mathematical models were developed to estimate the supply and demand for donor sperm and the feasibility of an ASD program...
January 14, 2017: Reproductive Health
https://www.readbyqxmd.com/read/28087782/mutation-supply-and-relative-fitness-shape-the-genotypes-of-ciprofloxacin-resistant-escherichia-coli
#4
Douglas L Huseby, Franziska Pietsch, Gerrit Brandis, Linnéa Garoff, Angelica Tegehall, Diarmaid Hughes
Ciprofloxacin is an important antibacterial drug targeting Type II topoisomerases, highly active against Gram-negatives including Escherichia coli The evolution of resistance to ciprofloxacin in E. coli always requires multiple genetic changes, usually including mutations affecting two different drug target genes, gyrA and parC Resistant mutants selected in vitro or in vivo can have many different mutations in target genes and efflux regulator genes that contribute to resistance. Among resistant clinical isolates the genotype, gyrA S83L D87N, parC S80I is significantly overrepresented suggesting that it has a selective advantage...
January 12, 2017: Molecular Biology and Evolution
https://www.readbyqxmd.com/read/28087422/nano-qsar-in-cell-biology-model-of-cell-viability-as-a-mathematical-function-of-available-eclectic-data
#5
Alla P Toropova, Andrey A Toropov
The prediction of biochemical endpoints is an important task of the modern medicinal chemistry, cell biology, and nanotechnology. Simplified molecular input-line entry system (SMILES) is a tool for representation of the molecular structure. In particular, SMILES can be used to build up the quantitative structure - property / activity relationships (QSPRs/QSARs). The QSPR/QSAR is a tool to predict an endpoint for a new substance, which has not been examined in experiment. Quasi-SMILES are representation of eclectic data related to an endpoint...
January 10, 2017: Journal of Theoretical Biology
https://www.readbyqxmd.com/read/28087352/engineering-hot-melt-extruded-solid-dispersion-for-controlled-release-of-hydrophilic-drugs
#6
Shuli Zhang, Xuan Meng, Zheng Wang, Aiping Fan, Guocheng Wang, Yanjun Zhao, Yu Tang
It is often challenging to precisely manipulate the release behavior of hydrophilic drugs that is believed to be crucial for a satisfactory therapeutic outcome. The aim of this work was to regulate the dissolution of hydrophilic drug from hot-melt extruded solid dispersion via rational screening of the pore-forming agents. Venlafaxine hydrochloride and Compritol® 888 ATO was selected as the model drug and carrier excipient, respectively. Hydrophilic polyethylene glycol (PEG 6000) and polyvinylpyrolidone (PVP K30) were chosen as the transient pore-forming agents...
January 10, 2017: European Journal of Pharmaceutical Sciences
https://www.readbyqxmd.com/read/28086846/stochastic-agent-based-modeling-of-tuberculosis-in-canadian-indigenous-communities
#7
Ashleigh R Tuite, Victor Gallant, Elaine Randell, Annie-Claude Bourgeois, Amy L Greer
BACKGROUND: In Canada, active tuberculosis (TB) disease rates remain disproportionately higher among the Indigenous population, especially among the Inuit in the north. We used mathematical modeling to evaluate how interventions might enhance existing TB control efforts in a region of Nunavut. METHODS: We developed a stochastic, agent-based model of TB transmission that captured the unique household and community structure. Evaluated interventions included: (i) rapid treatment of active cases; (ii) rapid contact tracing; (iii) expanded screening programs for latent TB infection (LTBI); and (iv) reduced household density...
January 13, 2017: BMC Public Health
https://www.readbyqxmd.com/read/28081545/mathematical-optimisation-of-the-cisplatin-plus-etoposide-combination-for-managing-extensive-stage-small-cell-lung-cancer-patients
#8
C Faivre, R El Cheikh, D Barbolosi, F Barlesi
BACKGROUND: Small-cell lung cancer (SCLC) represents one of the most aggressive forms of lung cancer. Despite the fair sensitivity of SCLC to chemotherapy and radiotherapy, the current standard treatment regimens have modest survival rates and are associated with potential life-threatening adverse events. Therefore, research into new optimised regimens that increase drug efficacy while respecting toxicity constraints is of primary importance. METHODS: A PK/PD model for the combination of cisplatin and etoposide to treat extensive-stage SCLC patients was generated...
January 12, 2017: British Journal of Cancer
https://www.readbyqxmd.com/read/28081004/reverberant-shear-wave-fields-and-estimation-of-tissue-properties
#9
Kevin J Parker, Juvenal Ormachea, Fernando Zvietcovich, Benjamin Castaneda
The determination of shear wave speed is an important subject in the field of elastography, since elevated shear wave speeds can be directly linked to increased stiffness of tissues. MRI and ultrasound scanners are frequently used to detect shear waves and a variety of estimators are applied to calculate the underlying shear wave speed. The estimators can be relatively simple if plane wave behavior is assumed with a known direction of propagation. However, multiple reflections from organ boundaries and internal inhomogeneities and mode conversions can create a complicated field in time and space...
January 12, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28079924/optimized-microwave-assistant-extraction-combined-ultrasonic-pretreatment-of-flavonoids-from-periploca-forrestii-schltr-and-evaluation-of-its-anti-allergic-activity
#10
Qian Liang, Huaguo Chen, Xin Zhou, Qingfang Deng, Enming Hu, Chao Zhao, Xiaojian Gong
Microwave extraction combined ultrasonic pretreatment of flavonoids from Periploca forrestii Schltr. was investigated in this study, extraction process was firstly performed in an ultrasonic cleaner, then treated by microwave irradiation. The optimum ultrasonic time of 25 min was selected by single-factor experiments. A response surface methodology (RSM) has been used to obtain a mathematical model that describes the process and analyzes the significant parameters ethanol concentration 59.92%, liquid to raw materials ratio 21...
January 12, 2017: Electrophoresis
https://www.readbyqxmd.com/read/28079498/how-place-and-audience-matter-perspectives-on-mathematics-plural-identities-from-late-1950s-french-and-english-middle-school-textbooks
#11
Catherine Radtka
Argument In this paper, I argue that studying school textbooks is a fruitful way to investigate mathematical conceptions in different national contexts. These sources give access to the written production of an extended mathematical milieu whose members write for various audiences. By studying the case of late 1950s French and English textbooks issued for a growing audience of 11- to 15-year-old pupils, I show that a plurality of conceptions was projected at the time onto pupils and their teachers in both national contexts...
December 2016: Science in Context
https://www.readbyqxmd.com/read/28079064/lasing-action-from-photonic-bound-states-in-continuum
#12
Ashok Kodigala, Thomas Lepetit, Qing Gu, Babak Bahari, Yeshaiahu Fainman, Boubacar Kanté
In 1929, only three years after the advent of quantum mechanics, von Neumann and Wigner showed that Schrödinger's equation can have bound states above the continuum threshold. These peculiar states, called bound states in the continuum (BICs), manifest themselves as resonances that do not decay. For several decades afterwards the idea lay dormant, regarded primarily as a mathematical curiosity. In 1977, Herrick and Stillinger revived interest in BICs when they suggested that BICs could be observed in semiconductor superlattices...
January 11, 2017: Nature
https://www.readbyqxmd.com/read/28077763/a-simplified-mathematical-model-of-directional-dna-site-specific-recombination-by-serine-integrases
#13
Alexandra Pokhilko, Jia Zhao, W Marshall Stark, Sean D Colloms, Oliver Ebenhöh
Serine integrases catalyse site-specific recombination to integrate and excise bacteriophage genomes into and out of their host's genome. These enzymes exhibit remarkable directionality; in the presence of the integrase alone, recombination between attP and attB DNA sites is efficient and irreversible, giving attL and attR products which do not recombine further. However, in the presence of the bacteriophage-encoded recombination directionality factor (RDF), integrase efficiently promotes recombination between attL and attR to re-form attP and attB The DNA substrates and products of both reactions are approximately isoenergetic, and no cofactors (such as adenosine triphosphate) are required for recombination...
January 2017: Journal of the Royal Society, Interface
https://www.readbyqxmd.com/read/28077441/predicting-ifn-%C3%AE-responses-after-bcg-vaccination-in-humans-from-macaques-a-proof-of-concept-study-of-immunostimulation-immunodynamic-modelling-methods
#14
Sophie J Rhodes, Charlotte Sarfas, Gwenan M Knight, Andrew White, Ansar A Pathan, Helen McShane, Thomas G Evans, Helen Fletcher, Sally Sharpe, Richard G White
INTRODUCTION: Macaques play a central role in human tuberculosis(TB) vaccine development. Immune and challenge responses differ across macaque and human subpopulations. We determined which macaque subpopulations best predicted immune responses in different human subpopulations, using novel immunostimulation/immunodynamic modelling methods in a proof of concept study. METHODS: Data on IFN-γ secreting CD4+ T cells over time after recent BCG vaccination were available for 55 humans and 81 macaques...
January 11, 2017: Clinical and Vaccine Immunology: CVI
https://www.readbyqxmd.com/read/28077304/drosophila-dorsal-closure-an-orchestra-of-forces-to-zip-shut-the-embryo
#15
REVIEW
Peran Hayes, Jérôme Solon
Dorsal closure, a late-embryogenesis process, consists in the sealing of an epidermal gap on the dorsal side of the Drosophila embryo. Because of its similarities with wound healing and neural tube closure in humans, it has been extensively studied in the last twenty years. The process requires the coordination of several force generating mechanisms, that together will zip shut the epidermis. Recent works have provided a precise description of the cellular behavior at the origin of these forces and proposed quantitative models of the process...
January 7, 2017: Mechanisms of Development
https://www.readbyqxmd.com/read/28077161/mathematical-modelling-of-echinococcus-multilocularis-abundance-in-foxes-in-zurich-switzerland
#16
Belen Otero-Abad, Simon R Rüegg, Daniel Hegglin, Peter Deplazes, Paul R Torgerson
BACKGROUND: In Europe, the red fox (Vulpes vulpes) is the main definitive host of Echinococcus multilocularis, the aetiological agent of a severe disease in humans called alveolar echinococcosis. The distribution of this zoonotic parasite among the fox population is remarkably aggregated with few heavily infected animals harbouring much of the parasite burdens and being responsible for most of the environmental parasitic egg contamination. Important research questions explored were: (i) spatial differences in parasite infection pressure related to the level of urbanization; (ii) temporal differences in parasite infection pressure in relation to time of the year; (iii) is herd immunity or an age-dependent infection pressure responsible for the observed parasite abundance; (iv) assuming E...
January 11, 2017: Parasites & Vectors
https://www.readbyqxmd.com/read/28076811/modeling-the-effect-of-curvature-on-the-collective-behavior-of-cells-growing-new-tissue
#17
Mohd Almie Alias, Pascal R Buenzli
The growth of several biological tissues is known to be controlled in part by local geometrical features, such as the curvature of the tissue interface. This control leads to changes in tissue shape that in turn can affect the tissue's evolution. Understanding the cellular basis of this control is highly significant for bioscaffold tissue engineering, the evolution of bone microarchitecture, wound healing, and tumor growth. Although previous models have proposed geometrical relationships between tissue growth and curvature, the role of cell density and cell vigor remains poorly understood...
January 10, 2017: Biophysical Journal
https://www.readbyqxmd.com/read/28076810/dna-occupancy-of-polymerizing-transcription-factors-a-chemical-model-of-the-ets-family-factor-yan
#18
C Matthew Hope, Ilaria Rebay, John Reinitz
Transcription factors use both protein-DNA and protein-protein interactions to assemble appropriate complexes to regulate gene expression. Although most transcription factors operate as monomers or dimers, a few, including the E26 transformation-specific family repressors Drosophila melanogaster Yan and its human homolog TEL/ETV6, can polymerize. Although polymerization is required for both the normal and oncogenic function of Yan and TEL/ETV6, the mechanisms by which it influences the recruitment, organization, and stability of transcriptional complexes remain poorly understood...
January 10, 2017: Biophysical Journal
https://www.readbyqxmd.com/read/28076681/computational-modeling-of-neurotransmitter-release-evoked-by-electrical-stimulation-non-linear-approaches-to-predicting-stimulation-evoked-dopamine-release
#19
James K Trevathan, Ali Yousefi, Hyung Ook Park, John J Bartoletta, Kip A Ludwig, Kendall H Lee, J Luis Lujan
Neurochemical changes evoked by electrical stimulation of the nervous system have been linked to both therapeutic and undesired effects of neuromodulation therapies used to treat obsessive-compulsive disorder, depression, epilepsy, Parkinson's disease, stroke, hypertension, tinnitus, and many other indications. In fact, interest in better understanding the role of neurochemical signaling in neuromodulation therapies has been a focus of recent government- and industry-sponsored programs whose ultimate goal is to usher in an era of personalized medicine by creating neuromodulation therapies that respond to real-time changes in patient status...
January 11, 2017: ACS Chemical Neuroscience
https://www.readbyqxmd.com/read/28075348/a-novel-monopulse-technique-for-adaptive-phased-array-radar
#20
Xinyu Zhang, Yang Li, Xiaopeng Yang, Le Zheng, Teng Long, Christopher J Baker
The monopulse angle measuring technique is widely adopted in radar systems due to its simplicity and speed in accurately acquiring a target's angle. However, in a spatial adaptive array, beam distortion, due to adaptive beamforming, can result in serious deterioration of monopulse performance. In this paper, a novel constrained monopulse angle measuring algorithm is proposed for spatial adaptive arrays. This algorithm maintains the ability to suppress the unwanted signals without suffering from beam distortion...
January 8, 2017: Sensors
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