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Theoretical Biology & Medical Modelling

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https://www.readbyqxmd.com/read/29132387/theoretically-proposed-optimal-frequency-for-ultrasound-induced-cartilage-restoration
#1
April D Miller, Anuradha Subramanian, Hendrik J Viljoen
BACKGROUND: Matching the frequency of the driving force to that of the system's natural frequency of vibration results in greater amplitude response. Thus we hypothesize that applying ultrasound at the chondrocyte's resonant frequency will result in greater deformation than applying similar ultrasound power at a frequency outside of the resonant bandwidth. Based on this resonant hypothesis, our group previously confirmed theoretically and experimentally that ultrasound stimulation of suspended chondrocytes at resonance (5 MHz) maximized gene expression of load inducible genes...
November 14, 2017: Theoretical Biology & Medical Modelling
https://www.readbyqxmd.com/read/29089031/anistropically-varying-conductivity-in-irreversible-electroporation-simulations
#2
Nicholas Labarbera, Corina Drapaca
BACKGROUND: One recent area of cancer research is irreversible electroporation (IRE). Irreversible electroporation is a minimally invasive procedure where needle electrodes are inserted into the body to ablate tumor cells with electricity. The aim of this paper is to propose a mathematical model that incorporates a tissue's conductivity increasing more in the direction of the electrical field as this has been shown to occur in experiments. METHOD: It was necessary to mathematically derive a valid form of the conductivity tensor such that it is dependent on the electrical field direction and can be easily implemented into numerical software...
November 1, 2017: Theoretical Biology & Medical Modelling
https://www.readbyqxmd.com/read/28992816/a-theoretical-model-of-the-wnt-signaling-pathway-in-the-epithelial-mesenchymal-transition
#3
Kelsey Gasior, Marlene Hauck, Alyson Wilson, Sudin Bhattacharya
BACKGROUND: Following the formation of a primary carcinoma, neoplastic cells metastasize by undergoing the epithelial mesenchymal transition (EMT), which is triggered by cues from inflammatory and stromal cells in the microenvironment. EMT allows epithelial cells to lose their highly adhesive nature and instead adopt the spindle-like appearance, as well as the invasive and migratory behavior, of mesenchymal cells. We hypothesize that a bistable switch between the epithelial and mesenchymal phenotypes governs EMT, allowing the cell to maintain its mesenchymal phenotype even after it leaves the primary tumor microenvironment and EMT-inducing extracellular signal...
October 10, 2017: Theoretical Biology & Medical Modelling
https://www.readbyqxmd.com/read/28969664/perspective-on-the-dynamics-of-cancer
#4
REVIEW
Youcef Derbal
BACKGROUND: The genetic diversity of cancer and the dynamic interactions between heterogeneous tumor cells, the stroma and immune cells present daunting challenges to the development of effective cancer therapies. Although cancer biology is more understood than ever, this has not translated into therapies that overcome drug resistance, cancer recurrence and metastasis. The future development of effective therapies will require more understanding of the dynamics of homeostatic dysregulation that drives cancer growth and progression...
October 3, 2017: Theoretical Biology & Medical Modelling
https://www.readbyqxmd.com/read/28874167/forecasting-infectious-disease-emergence-subject-to-seasonal-forcing
#5
Paige B Miller, Eamon B O'Dea, Pejman Rohani, John M Drake
BACKGROUND: Despite high vaccination coverage, many childhood infections pose a growing threat to human populations. Accurate disease forecasting would be of tremendous value to public health. Forecasting disease emergence using early warning signals (EWS) is possible in non-seasonal models of infectious diseases. Here, we assessed whether EWS also anticipate disease emergence in seasonal models. METHODS: We simulated the dynamics of an immunizing infectious pathogen approaching the tipping point to disease endemicity...
September 6, 2017: Theoretical Biology & Medical Modelling
https://www.readbyqxmd.com/read/28870213/test-and-treat-approach-to-hiv-aids-a-primer-for-mathematical-modeling
#6
REVIEW
Kyeongah Nah, Hiroshi Nishiura, Naho Tsuchiya, Xiaodan Sun, Yusuke Asai, Akifumi Imamura
The public benefit of test-and-treat has induced a need to justify goodness for the public, and mathematical modeling studies have played a key role in designing and evaluating the test-and-treat strategy for controlling HIV/AIDS. Here we briefly and comprehensively review the essence of contemporary understanding of the test-and-treat policy through mathematical modeling approaches and identify key pitfalls that have been identified to date. While the decrease in HIV incidence is achieved with certain coverages of diagnosis, care and continued treatment, HIV prevalence is not necessarily decreased and sometimes the test-and-treat is accompanied by increased long-term cost of antiretroviral therapy (ART)...
September 5, 2017: Theoretical Biology & Medical Modelling
https://www.readbyqxmd.com/read/28768512/theory-of-synergistic-effects-hill-type-response-surfaces-as-null-interaction-models-for-mixtures
#7
Michael Schindler
BACKGROUND: The classification of effects caused by mixtures of agents as synergistic, antagonistic or additive depends critically on the reference model of 'null interaction'. Two main approaches are currently in use, the Additive Dose (ADM) or concentration addition (CA) and the Multiplicative Survival (MSM) or independent action (IA) models. We compare several response surface models to a newly developed Hill response surface, obtained by solving a logistic partial differential equation (PDE)...
August 2, 2017: Theoretical Biology & Medical Modelling
https://www.readbyqxmd.com/read/28747188/transmission-dynamics-of-cholera-in-yemen-2017-a-real-time-forecasting
#8
Hiroshi Nishiura, Shinya Tsuzuki, Baoyin Yuan, Takayuki Yamaguchi, Yusuke Asai
BACKGROUND: A large epidemic of cholera, caused by Vibrio cholerae, serotype Ogawa, has been ongoing in Yemen, 2017. To improve the situation awareness, the present study aimed to forecast the cholera epidemic, explicitly addressing the reporting delay and ascertainment bias. METHODS: Using weekly incidence of suspected cases, updated as a revised epidemic curve every week, the reporting delay was explicitly incorporated into the estimation model. Using the weekly case fatality risk as calculated by the World Health Organization, ascertainment bias was adjusted, enabling us to parameterize the family of logistic curves (i...
July 26, 2017: Theoretical Biology & Medical Modelling
https://www.readbyqxmd.com/read/28716140/modelling-infectious-diseases-with-relapse-a-case-study-of-hsv-2
#9
Jinliang Wang, Xiaoqing Yu, Heidi L Tessmer, Toshikazu Kuniya, Ryosuke Omori
BACKGROUND: Herpes Simplex Virus Type 2 (HSV-2) is one of the most common sexually transmitted diseases. Although there is still no licensed vaccine for HSV-2, a theoretical investigation of the potential effects of a vaccine is considered important and has recently been conducted by several researchers. Although compartmental mathematical models were considered for each special case in the previous studies, as yet there are few global stability results. RESULTS: In this paper, we formulate a multi-group SVIRI epidemic model for HSV-2, which enables us to consider the effects of vaccination, of waning vaccine immunity, and of infection relapse...
July 17, 2017: Theoretical Biology & Medical Modelling
https://www.readbyqxmd.com/read/28578662/possible-contribution-of-quantum-like-correlations-to-the-placebo-effect-consequences-on-blind-trials
#10
Francis Beauvais
BACKGROUND: Factors that participate in the biological changes associated with a placebo are not completely understood. Natural evolution, mean regression, concomitant procedures and other non specific effects are well-known factors that contribute to the "placebo effect". In this article, we suggest that quantum-like correlations predicted by a probabilistic modeling could also play a role. RESULTS: An elementary experiment in biology or medicine comparing the biological changes associated with two placebos is modeled...
June 2, 2017: Theoretical Biology & Medical Modelling
https://www.readbyqxmd.com/read/28521828/markov-modeling-in-hepatitis-b-screening-and-linkage-to-care
#11
Martin A Sehr, Kartik D Joshi, John M Fontanesi, Robert J Wong, Robert R Bitmead, Robert G Gish
BACKGROUND: With up to 240 million people chronically infected with hepatitis B worldwide, including an estimated 2 million in the United States, widespread screening is needed to link the infected to care and decrease the possible consequences of untreated infection, including liver cancer, cirrhosis and death. Screening is currently fraught with challenges in both the developed and developing world. New point-of-care tests may have advantages over standard-of-care tests in terms of cost-effectiveness and linkage to care...
May 18, 2017: Theoretical Biology & Medical Modelling
https://www.readbyqxmd.com/read/28464925/image-driven-modeling-of-the-proliferation-and-necrosis-of-glioblastoma-multiforme
#12
Vishal Patel, Leith Hathout
BACKGROUND: The heterogeneity of response to treatment in patients with glioblastoma multiforme suggests that the optimal therapeutic approach incorporates an individualized assessment of expected lesion progression. In this work, we develop a novel computational model for the proliferation and necrosis of glioblastoma multiforme. METHODS: The model parameters are selected based on the magnetic resonance imaging features of each tumor, and the proposed technique accounts for intrinsic cell division, tumor cell migration along white matter tracts, as well as central tumor necrosis...
May 2, 2017: Theoretical Biology & Medical Modelling
https://www.readbyqxmd.com/read/28431573/a-highly-pathogenic-simian-human-immunodeficiency-virus-effectively-produces-infectious-virions-compared-with-a-less-pathogenic-virus-in-cell-culture
#13
Shoya Iwanami, Yusuke Kakizoe, Satoru Morita, Tomoyuki Miura, Shinji Nakaoka, Shingo Iwami
BACKGROUND: The host range of human immunodeficiency virus (HIV) is quite narrow. Therefore, analyzing HIV-1 pathogenesis in vivo has been limited owing to lack of appropriate animal model systems. To overcome this, chimeric simian and human immunodeficiency viruses (SHIVs) that encode HIV-1 Env and are infectious to macaques have been developed and used to investigate the pathogenicity of HIV-1 in vivo. So far, we have many SHIV strains that show different pathogenesis in macaque experiments...
April 21, 2017: Theoretical Biology & Medical Modelling
https://www.readbyqxmd.com/read/28388921/establishment-of-a-new-initial-dose-plan-for-vancomycin-using-the-generalized-linear-mixed-model
#14
Yasuyuki Kourogi, Kenji Ogata, Norito Takamura, Jin Tokunaga, Nao Setoguchi, Mitsuhiro Kai, Emi Tanaka, Susumu Chiyotanda
BACKGROUND: When administering vancomycin hydrochloride (VCM), the initial dose is adjusted to ensure that the steady-state trough value (Css-trough) remains within the effective concentration range. However, the Css-trough (population mean method predicted value [PMMPV]) calculated using the population mean method (PMM) often deviate from the effective concentration range. In this study, we used the generalized linear mixed model (GLMM) for initial dose planning to create a model that accurately predicts Css-trough, and subsequently assessed its prediction accuracy...
April 8, 2017: Theoretical Biology & Medical Modelling
https://www.readbyqxmd.com/read/28347332/an-outbreak-vector-host-epidemic-model-with-spatial-structure-the-2015-2016-zika-outbreak-in-rio-de-janeiro
#15
W E Fitzgibbon, J J Morgan, G F Webb
BACKGROUND: A deterministic model is developed for the spatial spread of an epidemic disease in a geographical setting. The disease is borne by vectors to susceptible hosts through criss-cross dynamics. The model is focused on an outbreak that arises from a small number of infected hosts imported into a subregion of the geographical setting. The goal is to understand how spatial heterogeneity of the vector and host populations influences the dynamics of the outbreak, in both the geographical spread and the final size of the epidemic...
March 27, 2017: Theoretical Biology & Medical Modelling
https://www.readbyqxmd.com/read/28327183/modeling-multi-mutation-and-drug-resistance-analysis-of-some-case-studies
#16
Mitra Shojania Feizabadi
BACKGROUND: Drug-induced resistance is one the major obstacles that may lead to therapeutic failure during cancer treatment. Different genetic alterations occur when tumor cells divide. Among new generations of tumor cells, some may express intrinsic resistance to a specific chemotherapeutic agent. Also, some tumor cells may carry a gene that can develop resistance induced by the therapeutic drug. The methods by which the therapeutic approaches need to be revised in the occurrence of drug induced resistance is still being explored...
March 21, 2017: Theoretical Biology & Medical Modelling
https://www.readbyqxmd.com/read/28320412/high-resolution-hemodynamic-profiling-of-murine-arteriovenous-fistula-using-magnetic-resonance-imaging-and-computational-fluid-dynamics
#17
Daniel Pike, Yan-Ting Shiu, Maheshika Somarathna, Lingling Guo, Tatyana Isayeva, John Totenhagen, Timmy Lee
BACKGROUND: Arteriovenous fistula (AVF) maturation failure remains a major cause of morbidity and mortality in hemodialysis patients. The two major etiologies of AVF maturation failure are early neointimal hyperplasia development and persistent inadequate outward remodeling. Although hemodynamic changes following AVF creation may impact AVF remodeling and contribute to neointimal hyperplasia development and impaired outward remodeling, detailed AVF hemodynamics are not yet fully known...
March 20, 2017: Theoretical Biology & Medical Modelling
https://www.readbyqxmd.com/read/28143579/method-for-generating-multiple-risky-barcodes-of-complex-diseases-using-ant-colony-algorithm
#18
Xiong Li, Wen Jiang
BACKGROUND: Susceptible barcode recognition plays an important role in the diagnosis and treatment of complex diseases. Numerous approaches have been proposed to identify risky barcodes involved in the progress of complex diseases. However, some methods only consider differences in barcode frequencies between the control and disease groups; as such, these methods may be partial or even wrong. For example, some barcodes with a high risk ratio yield a low frequency on cases or exhibit a high frequency on controls, which may unreasonable from a statistical point...
February 1, 2017: Theoretical Biology & Medical Modelling
https://www.readbyqxmd.com/read/28129769/the-role-of-mobility-and-health-disparities-on-the-transmission-dynamics-of-tuberculosis
#19
Victor Moreno, Baltazar Espinoza, Kamal Barley, Marlio Paredes, Derdei Bichara, Anuj Mubayi, Carlos Castillo-Chavez
BACKGROUND: The transmission dynamics of Tuberculosis (TB) involve complex epidemiological and socio-economical interactions between individuals living in highly distinct regional conditions. The level of exogenous reinfection and first time infection rates within high-incidence settings may influence the impact of control programs on TB prevalence. The impact that effective population size and the distribution of individuals' residence times in different patches have on TB transmission and control are studied using selected scenarios where risk is defined by the estimated or perceive first time infection and/or exogenous re-infection rates...
January 28, 2017: Theoretical Biology & Medical Modelling
https://www.readbyqxmd.com/read/28122568/thermodynamic-considerations-in-renal-separation-processes
#20
Robert H Louw, David M Rubin, David Glasser, Robyn F R Letts, Diane Hildebrandt
BACKGROUND: Urine production in the kidney is generally thought to be an energy-intensive process requiring large amounts of metabolic activity to power active transport mechanisms. This study uses a thermodynamic analysis to evaluate the minimum work requirements for urine production in the human kidney and provide a new perspective on the energy costs of urine production. In this study, black-box models are used to compare the Gibbs energy inflow and outflow of the overall kidney and physiologically-based subsections in the kidney, to calculate the work of separation for urine production...
January 26, 2017: Theoretical Biology & Medical Modelling
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