Journals Theoretical Biology & Medical ...

Theoretical Biology & Medical Modelling
Ryohei Saito, Akifumi Imamura, Hiroshi Nishiura
BACKGROUND: A hepatitis A epidemic occurred among men who have sex with men (MSM) in Japan in 2017-2018. In this study, we employ a parsimonious mathematical model to epidemiologically investigate the dynamics of infection, aiming to evaluate the effectiveness of campaign-based interventions among MSM to raise awareness of the situation. METHODS: A mathematical model describing a mixture of human-to-human transmission and environmental transmission was fitted to surveillance data...
October 11, 2021: Theoretical Biology & Medical Modelling
Hiromu Ito, Taro Yamamoto, Satoru Morita
Sexually transmitted infections (STIs) have remained a worldwide public health threat. It is difficult to control the spread of STIs, not only because of heterogeneous sexual transmission between men and women but also because of the complicated effects of sexual transmission among men who have sex with men (MSM) and mother-to-child transmission. Many studies point to the existence of a 'bisexual bridge', where STIs spread from the MSM network via bisexual connections. However, it is unclear how the MSM network affects heterosexual networks as well as mother-to-child transmission...
October 11, 2021: Theoretical Biology & Medical Modelling
Baoyin Yuan, Hyojung Lee, Hiroshi Nishiura
Travelers play a role in triggering epidemics of imported dengue fever because they can carry the virus to other countries during the incubation period. If a traveler carrying dengue virus visits open green space and is bitten by mosquitoes, a local outbreak can ensue. In the present study, we aimed to understand the movement patterns of international travelers in Tokyo using mobile phone data, with the goal of identifying geographical foci of dengue transmission. We analyzed datasets based on mobile phone access to WiFi systems and measured the spatial distribution of international visitors in Tokyo on two specific dates (one weekday in July 2017 and another weekday in August 2017)...
October 3, 2021: Theoretical Biology & Medical Modelling
Zvifadzo Matsena Zingoni, Tobias F Chirwa, Jim Todd, Eustasius Musenge
BACKGROUND: This study aimed to jointly model HIV disease progression patterns based on viral load (VL) among adult ART patients adjusting for the time-varying "incremental transients states" variable, and the CD4 cell counts orthogonal variable in a single 5-stage time-homogenous multistate Markov model. We further jointly mapped the relative risks of HIV disease progression outcomes (detectable VL (VL ≥ 50copies/uL) and immune deterioration (CD4 < 350cells/uL) at the last observed visit) conditional not to have died or become loss to follow-up (LTFU)...
August 21, 2021: Theoretical Biology & Medical Modelling
Hikaru Hoshino, Eiko Furutani
BACKGROUND: Nondepolarizing neuromuscular blocking drugs (NDNBs) are clinically used to produce muscle relaxation during general anesthesia. To better understand clinical properties of NDNBs, comparative in vitro pharmacologic studies have been performed. In these studies, a receptor binding model, which relies on the assumption that the inhibition, i.e., the effect of an NDNB, is proportional to the receptor occupancy by the drug, has been effectively used to describe obtained experimental data...
August 21, 2021: Theoretical Biology & Medical Modelling
Marcos Amaku, Dimas Tadeu Covas, Francisco Antonio Bezerra Coutinho, Raymundo Soares Azevedo, Eduardo Massad
BACKGROUND: At the moment we have more than 177 million cases and 3.8 million deaths (as of June 2021) around the world and vaccination represents the only hope to control the pandemic. Imperfections in planning vaccine acquisition and difficulties in implementing distribution among the population, however, have hampered the control of the virus so far. METHODS: We propose a new mathematical model to estimate the impact of vaccination delay against the 2019 coronavirus disease (COVID-19) on the number of cases and deaths due to the disease in Brazil...
July 29, 2021: Theoretical Biology & Medical Modelling
Hiroaki Murayama, Taishi Kayano, Hiroshi Nishiura
BACKGROUND: In Japan, a part of confirmed patients' samples have been screened for the variant of concern (VOC), including the variant alpha with N501Y mutation. The present study aimed to estimate the actual number of cases with variant alpha and reconstruct the epidemiological dynamics. METHODS: The number of cases with variant alpha out of all PCR confirmed cases was estimated, employing a hypergeometric distribution. An exponential growth model was fitted to the growth data of variant alpha cases over fourteen weeks in Tokyo...
July 17, 2021: Theoretical Biology & Medical Modelling
Ko Nakajo, Hiroshi Nishiura
BACKGROUND: Individuals with asymptomatic severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection can propagate the virus unknowingly and thus have been a focus of public health attentions since the early stages of the pandemic. Understanding viral transmissibility among asymptomatic individuals is critical for successful control of coronavirus disease 2019 (COVID-19). The present study aimed to understand SARS-CoV-2 transmissibility among young asymptomatic individuals and to assess whether symptomatology was associated with transmission of symptomatic vs...
July 16, 2021: Theoretical Biology & Medical Modelling
Pirmin Schlicke, Christina Kuttler, Christian Schumann
BACKGROUND: Cancer is one of the leading death causes globally with about 8.2 million deaths per year and an increase in numbers in recent years. About 90% of cancer deaths do not occur due to primary tumors but due to metastases, of which most are not clinically identifiable because of their relatively small size at primary diagnosis and limited technical possibilities. However, therapeutic decisions are formed depending on the existence of metastases and their properties. Therefore non-identified metastases might have huge influence in the treatment outcome...
June 2, 2021: Theoretical Biology & Medical Modelling
Shi Zhao, Jingzhi Lou, Lirong Cao, Hong Zheng, Marc K C Chong, Zigui Chen, Benny C Y Zee, Paul K S Chan, Maggie H Wang
BACKGROUND: The COVID-19 pandemic poses a serious threat to global health, and pathogenic mutations are a major challenge to disease control. We developed a statistical framework to explore the association between molecular-level mutation activity of SARS-CoV-2 and population-level disease transmissibility of COVID-19. METHODS: We estimated the instantaneous transmissibility of COVID-19 by using the time-varying reproduction number (Rt ). The mutation activity in SARS-CoV-2 is quantified empirically depending on (i) the prevalence of emerged amino acid substitutions and (ii) the frequency of these substitutions in the whole sequence...
March 9, 2021: Theoretical Biology & Medical Modelling
Gianluigi Zangari Del Balzo
No abstract text is available yet for this article.
March 5, 2021: Theoretical Biology & Medical Modelling
Ruby Kim, Michael C Reed
BACKGROUND: The superchiasmatic nucleus (SCN) serves as the primary circadian (24hr) clock in mammals and is known to control important physiological functions such as the sleep-wake cycle, hormonal rhythms, and neurotransmitter regulation. Experimental results suggest that some of these functions reciprocally influence circadian rhythms, creating a highly complex network. Among the clock's downstream products, orphan nuclear receptors REV-ERB and ROR are particularly interesting because they coordinately modulate the core clock circuitry...
February 17, 2021: Theoretical Biology & Medical Modelling
Masaya M Saito, Nobuo Hirotsu, Hiroka Hamada, Mio Takei, Keisuke Honda, Takamichi Baba, Takahiro Hasegawa, Yoshitake Kitanishi
BACKGROUND: Influenza is a public health issue that needs to be addressed strategically. The assessment of detailed infectious profiles is an important part of this effort. Household transmission data play a key role in estimating such profiles. We used diagnostic and questionnaire-based data on influenza patients at a Japanese clinic to estimate the detailed infectious period (as well as incubation period, symptomatic and infectious periods, and extended infectious period after recovery) and the secondary attack ratio (SAR) of influenza for households of various sizes based on a modified Cauchemez-type model...
February 10, 2021: Theoretical Biology & Medical Modelling
Fan He, Lu Hua, Tingting Guo
BACKGROUND: The effects of arterial wall compliance on blood flow have been revealed using fluid-structure interaction in last decades. However, microcirculation is not considered in previous researches. In fact, microcirculation plays a key role in regulating blood flow. Therefore, it is very necessary to involve microcirculation in arterial hemodynamics. OBJECTIVE: The main purpose of the present study is to investigate how wall compliance affects the flow characteristics and to establish the comparisons of these flow variables with rigid wall when microcirculation is considered...
January 19, 2021: Theoretical Biology & Medical Modelling
Yusuke Kakizoe, Yoshiki Koizumi, Yukino Ikoma, Hirofumi Ohashi, Takaji Wakita, Shingo Iwami, Koichi Watashi
No abstract text is available yet for this article.
January 19, 2021: Theoretical Biology & Medical Modelling
Yusuke Kakizoe, Yoshiki Koizumi, Yukino Ikoma, Hirofumi Ohashi, Takaji Wakita, Shingo Iwami, Koichi Watashi
Successful clinical drug development requires rational design of combination treatments based on preclinical data. Anti-hepatitis C virus (HCV) drugs exhibit significant diversity in antiviral effect. Dose-response assessments can be used to determine parameters profiling the diverse antiviral effect during combination treatment. In the current study, a combined experimental and mathematical approaches were used to compare and score different combinations of anti-HCV treatments. A "required concentration index" was generated and used to rank the antiviral profile of possible double- and triple-drug combinations against HCV genotype 1b and 2a...
January 9, 2021: Theoretical Biology & Medical Modelling
Kkwh Erandi, Ssn Perera, A C Mahasinghe
BACKGROUND: Understanding the dynamical behavior of dengue transmission is essential in designing control strategies. Mathematical models have become an important tool in describing the dynamics of a vector borne disease. Classical compartmental models are well-known method used to identify the dynamical behavior of spread of a vector borne disease. Due to use of fixed model parameters, the results of classical compartmental models do not match realistic nature. The aim of this study is to introduce time in varying model parameters, modify the classical compartmental model by improving its predictability power...
January 7, 2021: Theoretical Biology & Medical Modelling
Gianluigi Zangari Del Balzo
BACKGROUND: Stochastic processes leading voltage-gated ion channel dynamics on the nerve cell membrane are a sufficient condition to describe membrane conductance through statistical mechanics of disordered and complex systems. RESULTS: Voltage-gated ion channels in the nerve cell membrane are described by the Ising model. Stochastic circuit elements called "Ising Neural Machines" are introduced. Action potentials are described as quasi-particles of a statistical field theory for the Ising system...
January 6, 2021: Theoretical Biology & Medical Modelling
Alibek Issakhov, Yeldos Zhandaulet, Aizhan Abylkassymova, Assylbek Issakhov
The functions of the nasal cavity are very important for maintaining the internal environment of the lungs since the inner walls of the nasal cavity control the temperature and saturation of the inhaled air with water vapor until the nasopharynx is reached. In this paper, three-dimensional computational studies of airflow transport in the models of the nasal cavity were carried out for the usual inspiratory velocity in various environmental conditions. Three-dimensional numerical results are compared with experimental data and calculations of other authors...
January 6, 2021: Theoretical Biology & Medical Modelling
Keita Yoshii, Hiroshi Nishiura, Kaoru Inoue, Takayuki Yamaguchi, Akihiko Hirose
BACKGROUND: To employ the benchmark dose (BMD) method in toxicological risk assessment, it is critical to understand how the BMD lower bound for reference dose calculation is selected following statistical fitting procedures of multiple mathematical models. The purpose of this study was to compare the performances of various combinations of model exclusion and selection criteria for quantal response data. METHODS: Simulation-based evaluation of model exclusion and selection processes was conducted by comparing validity, reliability, and other model performance parameters...
August 5, 2020: Theoretical Biology & Medical Modelling
Fetch more papers »
Fetching more papers... Fetching...
Remove bar
Read by QxMD icon Read

Save your favorite articles in one place with a free QxMD account.


Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"

We want to hear from doctors like you!

Take a second to answer a survey question.