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Mathematical modelling

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https://www.readbyqxmd.com/read/28092933/estimation-of-the-size-of-the-iatrogenic-creutzfeldt-jakob-disease-outbreak-associated-with-cadaveric-dura-mater-grafts-in-korea
#1
Byoug-Hak Jeon, Jinseob Kim, GangHyun Kim Kim, Soo Chul Park, SangYun Kim, Hae-Kwan Cheong
Purpose: This study estimated the overall magnitude of Creutzfeldt-Jakob disease (iCJD) based on dura graft cases in Korea using a mathematical model. Methods: We estimated the number of annual cases of dura grafts performed between 1980 and 1995 by applying the proportion of dura grafts recorded by the Health Insurance Review Agency claim dataset in Korea to the number of nationwide neurosurgery cases. The distribution of the incubation period was assumed to fall under a Weibull distribution with density function or a log-logistic distribution with density function...
December 19, 2016: Epidemiology and Health
https://www.readbyqxmd.com/read/28092602/the-investigation-of-correlation-among-selected-biochemical-parameters-and-vital-signs-in-dairy-herd-to-design-the-bio-cybernetic-dairy-cow-model
#2
J Twardoń, W Zalewski, T Nowicki, B Dębski, G Dejneka, J Mrowiec, K Zalewski
The paper presents investigations of the relationship between the biochemical parameters and vital signs in dairy cows. We analyzed the welfare and functioning of a dairy herd using biochemical parameters and vital signs. Life and biochemical parameters were examined. In the model indicators useful for monitoring the herd are: the age of the cows, the number of cows' lactating, daily amount of received milk, length of lactation period for cows in the herd, the length of inter-calving period for cows, the number of days to effective insemination, the amount of protein in the feed, the level of β-oxidation in leucocytes, glucose transport through red blood cells and plasma insulin...
December 1, 2016: Polish Journal of Veterinary Sciences
https://www.readbyqxmd.com/read/28092504/wall-shear-rate-measurement-validation-of-a-new-method-through-multiphysics-simulations
#3
Stefano Ricci, Abigail Swillens, Alessandro Ramalli, Patrick Segers, Piero Tortoli
Wall shear stress is known to affect the vessel endothelial function and to be related to important pathologies like the development of atherosclerosis. It is defined as the product of the blood viscosity by the blood velocity gradient at the wall position, i.e., the wall shear rate (WSR). The WSR measurement is particularly challenging in important cardiovascular sites, like the carotid bifurcation, because of the related complex flow configurations characterized by high spatial and temporal gradients, wall movement, and clutter noise...
January 2017: IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control
https://www.readbyqxmd.com/read/28092500/a-model-of-a-synthetic-biological-communication-interface-between-mammalian-cells-and-mechatronic-systems
#4
Keith C Heyde, Warren C Ruder
The creation of communication interfaces between abiotic and biotic systems represents a significant research challenge. In this work, we design and model a system linking the biochemical signaling pathways of mammalian cells to the actions of a mobile robotic prosthesis. We envision this system as a robotic platform carrying an optically monitored bioreactor that harbors mammalian cells. The cellular, optical signal is captured by an onboard fluorescent microscope and converted into an electronic signal. We first present a design for the overall cell-robot system, with a specific focus on the design of the synthetic gene networks needed for the system...
December 2016: IEEE Transactions on Nanobioscience
https://www.readbyqxmd.com/read/28091537/spatio-temporal-coordination-among-functional-residues-in-protein
#5
Sutapa Dutta, Mahua Ghosh, J Chakrabarti
The microscopic basis of communication among the functional sites in bio-macromolecules is a fundamental challenge in uncovering their functions. We study the communication through temporal cross-correlation among the binding sites. We illustrate via Molecular Dynamics simulations the properties of the temporal cross-correlation between the dihedrals of a small protein, ubiquitin which participates in protein degradation in eukaryotes. We show that the dihedral angles of the residues possess non-trivial temporal cross-correlations with asymmetry with respect to exchange of the dihedrals, having peaks at low frequencies with time scales in nano-seconds and an algebraic tail with a universal exponent for large frequencies...
January 16, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28090737/a-framework-for-how-environment-contributes-to-cancer-risk
#6
Michael E Hochberg, Robert J Noble
Evolutionary theory explains why metazoan species are largely protected against the negative fitness effects of cancers. Nevertheless, cancer is often observed at high incidence across a range of species. Although there are many challenges to quantifying cancer epidemiology and assessing its causes, we claim that most modern-day cancer in animals - and humans in particular - are due to environments deviating from central tendencies of distributions that have prevailed during cancer resistance evolution. Such novel environmental conditions may be natural and/or of anthropogenic origin, and may interface with cancer risk in numerous ways, broadly classifiable as those: increasing organism body size and/or life span, disrupting processes within the organism, and affecting germline...
January 16, 2017: Ecology Letters
https://www.readbyqxmd.com/read/28090101/a-novel-mathematical-model-for-determining-faculty-workload
#7
Leo R Fitzpatrick, Carol Millette-Snodgrass, Eman Atef
Objective. To develop a mathematical model for determining faculty workload at a college of pharmacy with a team-based learning curriculum. Methods. Using faculty provided data, our model calculated activity and weighted means in teaching, scholarship and service. Subsequently, these data were used to develop departmental and institutional workload models. Results. For the pharmaceutical and biomedical sciences department, percent faculty activity mean values were greatest for service followed by teaching and scholarship...
November 25, 2016: American Journal of Pharmaceutical Education
https://www.readbyqxmd.com/read/28090032/the-influence-of-elastic-moduli-of-core-materials-on-shear-stress-distributions-at-the-adhesive-interface-in-resin-built-up-teeth
#8
Ayaka Chiba, Takashi Hatayama, Kimisuke Kainose, Masatoshi Nakajima, David H Pashley, Noriyuki Wakabayashi, Junji Tagami
This study aimed to investigate shear stress distributions in resin built-up teeth using resin composites of varying elastic moduli (E), with or without fiber posts. Three-dimensional mathematical models of a root-filled mandibular premolar tooth were constructed. Resin post and cores were built-up with resin composites of three different E: 12,000, 18,000 and 24,000 MPa, with or without fiber posts. Finite element linear analysis was performed to calculate shear stress distributions at bonding interface between resin core and dentin...
January 13, 2017: Dental Materials Journal
https://www.readbyqxmd.com/read/28089874/mathematical-modelling-of-cell-layer-growth-in-a-hollow-fibre-bioreactor
#9
Lloyd A C Chapman, Jonathan P Whiteley, Helen M Byrne, Sarah L Waters, Rebecca J Shipley
Generating autologous tissue grafts of a clinically useful volume requires efficient and controlled expansion of cell populations harvested from patients. Hollow fibre bioreactors show promise as cell expansion devices, owing to their potential for scale-up. However, further research is required to establish how to specify appropriate hollow fibre bioreactor operating conditions for expanding different cell types. In this study we develop a simple model for the growth of a cell layer seeded on the outer surface of a single fibre in a perfused hollow fibre bioreactor...
January 12, 2017: Journal of Theoretical Biology
https://www.readbyqxmd.com/read/28089515/navigation-through-the-plasma-membrane-molecular-landscape-shapes-random-organelle-movement
#10
Alison R Dun, Gabriel J Lord, Rhodri S Wilson, Deirdre M Kavanagh, Katarzyna I Cialowicz, Shuzo Sugita, Seungmee Park, Lei Yang, Annya M Smyth, Andreas Papadopulos, Colin Rickman, Rory R Duncan
Eukaryotic plasma membrane organization theory has long been controversial, in part due to a dearth of suitably high-resolution techniques to probe molecular architecture in situ and integrate information from diverse data streams [1]. Notably, clustered patterning of membrane proteins is a commonly conserved feature across diverse protein families (reviewed in [2]), including the SNAREs [3], SM proteins [4, 5], ion channels [6, 7], and receptors (e.g., [8]). Much effort has gone into analyzing the behavior of secretory organelles [9-13], and understanding the relationship between the membrane and proximal organelles [4, 5, 12, 14] is an essential goal for cell biology as broad concepts or rules may be established...
January 9, 2017: Current Biology: CB
https://www.readbyqxmd.com/read/28088672/using-discrete-multi-physics-for-detailed-exploration-of-hydrodynamics-in-an-in-vitro-colon-system
#11
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
#12
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
#13
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
#14
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
#15
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
#16
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
#17
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
#18
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
#19
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...
February 7, 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
#20
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
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