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Theoretical Biology & Medical Modelling

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https://www.readbyqxmd.com/read/30008270/determinants-of-viral-load-rebound-on-hiv-aids-patients-receiving-antiretroviral-therapy-results-from-south-africa
#1
Claris Shoko, Delson Chikobvu
BACKGROUND: Antiretroviral therapy (ART) has become the standard of care for patients with HIV infection in South Africa and has led to the reduction in AIDS related morbidity and mortality. In developing countries, the nucleosides reverse transcriptase inhibitors (NRTIs) class are widely used because of their low production costs. However patients treated with NRTIs develop varying degree of toxicity after long-term therapy. For this study patients are administered with a triple therapy of two NRTIs and one non-nucleoside reverse transcriptase inhibitor (NNRTI)...
July 16, 2018: Theoretical Biology & Medical Modelling
https://www.readbyqxmd.com/read/29961429/modeling-the-elevated-risk-of-yellow-fever-among-travelers-visiting-brazil-2018
#2
Yohei Sakamoto, Takayuki Yamaguchi, Nao Yamamoto, Hiroshi Nishiura
BACKGROUND: Unlike the epidemic of yellow fever from 2016 to 17 in Brazil mostly restricted to the States of Minas Gerais and Espirito Santo, the epidemic from 2017 to 18 mainly involved São Paulo and Rio de Janeiro and resulted in multiple international disseminations. To understand mechanisms behind this observation, the present study analyzed the distribution of imported cases from Brazil, 2018. METHODS: A statistical model was employed to capture the risk of importing yellow fever by returning international travelers from Brazil...
July 2, 2018: Theoretical Biology & Medical Modelling
https://www.readbyqxmd.com/read/29925399/a-model-of-hematopoietic-bone-marrow-apoptosis-during-growth-factor-deprivation-in-combination-with-a-cytokine
#3
Christina L Mouser, Eliana S Antoniou, Evros K Vassiliou
BACKGROUND: The process by which blood cells are formed is referred to as hematopoiesis. This process involves a complex sequence of phases that blood cells must complete. During hematopoiesis, a small fraction of cells undergo cell death. Causes of cell death are dependent upon various factors; one such factor being growth factor deprivation. METHODS: In this paper, a mathematical model of hematopoiesis during growth factor deprivation is presented. The model consists of a set of three coupled differential delay equations...
June 21, 2018: Theoretical Biology & Medical Modelling
https://www.readbyqxmd.com/read/29879998/outside-host-phage-therapy-as-a-biological-control-against-environmental-infectious-diseases
#4
Ilona Merikanto, Jouni T Laakso, Veijo Kaitala
BACKGROUND: Environmentally growing pathogens present an increasing threat for human health, wildlife and food production. Treating the hosts with antibiotics or parasitic bacteriophages fail to eliminate diseases that grow also in the outside-host environment. However, bacteriophages could be utilized to suppress the pathogen population sizes in the outside-host environment in order to prevent disease outbreaks. Here, we introduce a novel epidemiological model to assess how the phage infections of the bacterial pathogens affect epidemiological dynamics of the environmentally growing pathogens...
June 8, 2018: Theoretical Biology & Medical Modelling
https://www.readbyqxmd.com/read/29848374/modelling-the-impact-of-correlations-between-condom-use-and-sexual-contact-pattern-on-the-dynamics-of-sexually-transmitted-infections
#5
Nao Yamamoto, Keisuke Ejima, Hiroshi Nishiura
BACKGROUND: It is believed that sexually active people, i.e. people having multiple or concurrent sexual partners, are at a high risk of sexually transmitted infections (STI), but they are likely to be more aware of the risk and may exhibit greater fraction of the use of condom. The purpose of the present study is to examine the correlation between condom use and sexual contact pattern and clarify its impact on the transmission dynamics of STIs using a mathematical model. METHODS: The definition of sexual contact pattern can be broad, but we focus on two specific aspects: (i) type of partnership (i...
May 31, 2018: Theoretical Biology & Medical Modelling
https://www.readbyqxmd.com/read/29743086/numerical-study-of-entrainment-of-the-human-circadian-system-and-recovery-by-light-treatment
#6
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
#7
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
#8
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
#9
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
#10
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
#11
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
#12
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
#13
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
#14
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
#15
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
#16
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
#17
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
#18
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
#19
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
#20
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
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