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Theoretical Biology & Medical Modelling

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https://www.readbyqxmd.com/read/29743086/numerical-study-of-entrainment-of-the-human-circadian-system-and-recovery-by-light-treatment
#1
Soon Ho Kim, Segun Goh, Kyungreem Han, Jong Won Kim, MooYoung Choi
BACKGROUND: While the effects of light as a zeitgeber are well known, the way the effects are modulated by features of the sleep-wake system still remains to be studied in detail. METHODS: A mathematical model for disturbance and recovery of the human circadian system is presented. The model combines a circadian oscillator and a sleep-wake switch that includes the effects of orexin. By means of simulations, we characterize the period-locking zone of the model, where a stable 24-hour circadian rhythm exists, and the occurrence of circadian disruption due to both insufficient light and imbalance in orexin...
May 9, 2018: Theoretical Biology & Medical Modelling
https://www.readbyqxmd.com/read/29510759/on-the-suitability-of-an-allometric-proxy-for-nondestructive-estimation-of-average-leaf-dry-weight-in-eelgrass-shoots-i-sensitivity-analysis-and-examination-of-the-influences-of-data-quality-analysis-method-and-sample-size-on-precision
#2
Héctor Echavarría-Heras, Cecilia Leal-Ramírez, Enrique Villa-Diharce, Nohe Cazarez-Castro
BACKGROUND: The effects of current anthropogenic influences on eelgrass (Zostera marina) meadows are noticeable. Eelgrass ecological services grant important benefits for mankind. Preservation of eelgrass meadows include several transplantation methods. Evaluation of establishing success relies on the estimation of standing stock and productivity. Average leaf biomass in shoots is a fundamental component of standing stock. Existing methods of leaf biomass measurement are destructive and time consuming...
March 6, 2018: Theoretical Biology & Medical Modelling
https://www.readbyqxmd.com/read/29386017/a-review-of-influenza-detection-and-prediction-through-social-networking-sites
#3
REVIEW
Ali Alessa, Miad Faezipour
Early prediction of seasonal epidemics such as influenza may reduce their impact in daily lives. Nowadays, the web can be used for surveillance of diseases. Search engines and social networking sites can be used to track trends of different diseases seven to ten days faster than government agencies such as Center of Disease Control and Prevention (CDC). CDC uses the Illness-Like Influenza Surveillance Network (ILINet), which is a program used to monitor Influenza-Like Illness (ILI) sent by thousands of health care providers in order to detect influenza outbreaks...
February 1, 2018: Theoretical Biology & Medical Modelling
https://www.readbyqxmd.com/read/29343268/time-homogeneous-markov-process-for-hiv-aids-progression-under-a-combination-treatment-therapy-cohort-study-south-africa
#4
Claris Shoko, Delson Chikobvu
BACKGROUND: As HIV enters the human body, its main target is the CD4 cell which it turns into a factory that produces millions of other HIV particles. These HIV particles target new CD4 cells resulting in the progression of HIV infection to AIDS. A continuous depletion of CD4 cells results in opportunistic infections, for example tuberculosis (TB). The purpose of this study is to model and describe the progression of HIV/AIDS disease in an individual on antiretroviral therapy (ART) follow up using a continuous time homogeneous Markov process...
January 18, 2018: Theoretical Biology & Medical Modelling
https://www.readbyqxmd.com/read/29310665/a-patient-specific-treatment-model-for-graves-hyperthyroidism
#5
Balamurugan Pandiyan, Stephen J Merrill, Flavia Di Bari, Alessandro Antonelli, Salvatore Benvenga
BACKGROUND: Graves' is disease an autoimmune disorder of the thyroid gland caused by circulating anti-thyroid receptor antibodies (TRAb) in the serum. TRAb mimics the action of thyroid stimulating hormone (TSH) and stimulates the thyroid hormone receptor (TSHR), which results in hyperthyroidism (overactive thyroid gland) and goiter. Methimazole (MMI) is used for hyperthyroidism treatment for patients with Graves' disease. METHODS: We have developed a model using a system of ordinary differential equations for hyperthyroidism treatment with MMI...
January 9, 2018: Theoretical Biology & Medical Modelling
https://www.readbyqxmd.com/read/29254493/on-the-utility-of-a-compartmental-population-kinetics-model-of-intestinal-epithelial-stem-cell-proliferation-and-differentiation
#6
Erik R Barthel
BACKGROUND: The small intestinal epithelium is a dynamic system with specialized cell types. The various cell populations of this tissue are continually renewed and replenished from stem cells that reside in the small intestinal crypt. The cell types and their locations in the crypt and villus are well known, but the details of the kinetics of stem cell division, and precursor cell proliferation and differentiation into mature enterocytes and secretory cells are still being studied. These proliferation and differentiation events have been extensively modeled with a variety of computational approaches in the past...
December 19, 2017: Theoretical Biology & Medical Modelling
https://www.readbyqxmd.com/read/29237462/effects-of-pathogen-dependency-in-a-multi-pathogen-infectious-disease-system-including-population-level-heterogeneity-a-simulation-study
#7
Abhishek Bakuli, Frank Klawonn, André Karch, Rafael Mikolajczyk
BACKGROUND: Increased computational resources have made individual based models popular for modelling epidemics. They have the advantage of incorporating heterogeneous features, including realistic population structures (like e.g. households). Existing stochastic simulation studies of epidemics, however, have been developed mainly for incorporating single pathogen scenarios although the effect of different pathogens might directly or indirectly (e.g. via contact reductions) effect the spread of each pathogen...
December 13, 2017: Theoretical Biology & Medical Modelling
https://www.readbyqxmd.com/read/29228966/estimating-the-prevalence-of-infectious-diseases-from-under-reported-age-dependent-compulsorily-notification-databases
#8
Marcos Amaku, Marcelo Nascimento Burattini, Eleazar Chaib, Francisco Antonio Bezerra Coutinho, David Greenhalgh, Luis Fernandez Lopez, Eduardo Massad
BACKGROUND: National or local laws, norms or regulations (sometimes and in some countries) require medical providers to report notifiable diseases to public health authorities. Reporting, however, is almost always incomplete. This is due to a variety of reasons, ranging from not recognizing the diseased to failures in the technical or administrative steps leading to the final official register in the disease notification system. The reported fraction varies from 9 to 99% and is strongly associated with the disease being reported...
December 12, 2017: Theoretical Biology & Medical Modelling
https://www.readbyqxmd.com/read/29228949/a-mathematical-model-for-histamine-synthesis-release-and-control-in-varicosities
#9
Janet Best, H F Nijhout, Srimal Samaranayake, Parastoo Hashemi, Michael Reed
BACKGROUND: Histamine (HA), a small molecule that is synthesized from the amino acid histidine, plays an important role in the immune system where it is associated with allergies, inflammation, and T-cell regulation. In the brain, histamine is stored in mast cells and other non-neuronal cells and also acts as a neurotransmitter. The histamine neuron cell bodies are in the tuberomammillary (TM) nucleus of the hypothalamus and these neurons send projections throughout the central nervous system (CNS), in particular to the cerebral cortex, amygdala, basal ganglia, hippocampus, thalamus, retina, and spinal cord...
December 12, 2017: Theoretical Biology & Medical Modelling
https://www.readbyqxmd.com/read/29202763/classification-and-sensitivity-analysis-of-the-transmission-dynamic-of-hepatitis-b
#10
REVIEW
Tahir Khan, Il Hyo Jung, Amir Khan, Gul Zaman
BACKGROUND: Hepatitis B infection caused by the hepatitis B virus is one of the most serious viral infections and a global health problem. In the transmission of hepatitis B infection, three different phases, i.e. acute infected, chronically infected, and carrier individuals, play important roles. Carrier individuals are especially significant, because they do not exhibit any symptoms and are able to transmit the infection. Here we assessed the transmissibility associated with different infection stages of hepatitis B and generated an epidemic model...
December 5, 2017: Theoretical Biology & Medical Modelling
https://www.readbyqxmd.com/read/29132387/theoretically-proposed-optimal-frequency-for-ultrasound-induced-cartilage-restoration
#11
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
#12
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
#13
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
#14
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
#15
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
#16
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
#17
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
#18
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
#19
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
#20
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
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