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Basic reproductive number

Panyu Chen, Tingting Li, Lei Jia, Cong Fang, Xiaoyan Liang
The purpose of this study is to determine whether all-blastocyst-culture can benefit advanced maternal age (AMA) patients with low ovarian reserve. We retrospectively analyze AMA patients with low ovarian reserve undergoing IVF/ICSI in Reproductive Medicine Research Center of the Sixth Affiliated Hospital of Sun Yat-sen University from May 2016 to August 2017. We divide them into group A (all-blastocyst-culture) and group B (none-blastocystculture) based on different culture approach of D3 transferrable embryo...
March 16, 2018: Gynecological Endocrinology
Steven Abrams, Andreas Wienke, Niel Hens
Frailty models are often used in survival analysis to model multivariate time-to-event data. In infectious disease epidemiology, frailty models have been proposed to model heterogeneity in the acquisition of infection and to accommodate association in the occurrence of multiple types of infection. Although traditional frailty models rely on the assumption of lifelong immunity after recovery, refinements have been made to account for reinfections with the same pathogen. Recently, Abrams and Hens quantified the effect of misspecifying the underlying infection process on the basic and effective reproduction number in the context of bivariate current status data on parvovirus B19 and varicella zoster virus...
April 2018: Journal of the Royal Statistical Society. Series C, Applied Statistics
Adrienne M Antonson, Bindu Balakrishnan, Emily C Radlowski, Geraldine Petr, Rodney W Johnson
Maternal infection during pregnancy increases the risk of neurobehavioral problems in offspring. Evidence from rodent models indicates that the maternal immune response to infection can alter fetal brain development, particularly in the hippocampus. However, information on the effects of maternal viral infection on fetal brain development in gyrencephalic species is limited. Thus, the objective of this study was to assess several effects of maternal viral infection in the last one-third of gestation on hippocampal gene expression and development in fetal piglets...
March 14, 2018: Developmental Neuroscience
Xinmiao Rong, Meng Fan, Xiangdong Sun, Youming Wang, Huaiping Zhu
Echinococcosis has been recognized as one of the most important helminth zoonosis in China. Available models always consider dogs as the mainly definitive hosts. However, such models ignore the distinctions between domestic dogs and stray dogs. In this study, we propose a 10-dimensional dynamic model distinguishing stray dogs from domestic dogs to explore the special role of stray dogs and potential effects of disposing stray dogs on the transmission of Echinococcosis. The basic reproduction number R0 , which measures the impact of both domestic dogs and stray dogs on the transmission, is determined to characterize the transmission dynamics...
March 8, 2018: Mathematical Biosciences
Sung Don Lim, Won Cheol Yim, Degao Liu, Rongbin Hu, Xiaohan Yang, John C Cushman
Strategies for improving plant size are critical targets for plant biotechnology to increase vegetative biomass or reproductive yield. To improve biomass production, a codon-optimized helix-loop-helix transcription factor (VvCEB1opt ) from wine grape was overexpressed in Arabidopsis thaliana resulting in significantly increased leaf number, leaf and rosette area, fresh weight, and dry weight. Cell size, but typically not cell number, was increased in all tissues resulting in increased vegetative biomass and reproductive organ size, number, and seed yield...
March 9, 2018: Plant Biotechnology Journal
Snežana Medić, Michalis Katsilieris, Zagorka Lozanov-Crvenković, Constantinos I Siettos, Vladimir Petrović, Vesna Milošević, Snežana Brkić, Nick Andrews, Milan Ubavić, Cleo Anastassopoulou
This study aimed at establishing baseline key epidemiological parameters for varicella zoster virus (VZV) infection in Vojvodina, Serbia, with the ultimate goal to quantify the VZV transmission potential in the population. Seroprevalence data generated during the first large cross-sectional VZV serosurvey were modelled, using a two-tiered modelling approach to calculate age-specific forces of infection (FOI), the basic reproduction number (R0) and herd immunity threshold (H). Seroprevalence and modelling data were compared with corresponding pre-vaccination epidemiological parameters from 11 countries participating in the European Sero-Epidemiology Network 2 (ESEN2) project...
2018: PloS One
Manuela T Comelis, Larissa M Bueno, Rejane M Góes, S R Taboga, Eliana Morielle-Versute
The penis is the reproductive organ that ensures efficient copulation and success of internal fertilization in all species of mammals, with special challenges for bats, where copulation can occur during flight. Comparative anatomical analyses of different species of bats can contribute to a better understanding of morphological diversity of this organ, concerning organization and function. In this study, we describe the external morphology and histomorphology of the penis and baculum in eleven species of molossid bats...
January 31, 2018: Zoology: Analysis of Complex Systems, ZACS
Juping Zhang, Chris Cosner, Huaiping Zhu
A two-patch model for the spread of West Nile virus between two discrete geographic regions is established to incorporate a mobility process which describes how contact transmission occurs between individuals from and between two regions. In the mobility process, we assume that the host birds can migrate between regions, but not the mosquitoes. The basic reproduction number [Formula: see text] is computed by the next generation matrix method. We prove that if [Formula: see text], then the disease-free equilibrium is globally asymptotically stable...
February 28, 2018: Bulletin of Mathematical Biology
Pablo Orellano, Darío Vezzani, Nancy Quaranta, Rodolfo Cionco, Julieta Reynoso, Oscar Salomon
OBJECTIVE: To assess the potential occurrence of Zika transmission throughout Argentina by the mosquito Aedes aegypti considering the basic reproduction number (R0). METHODS: A model originally developed for dengue was adapted for Zika. R0 was estimated as a function of seven parameters, three of them were considered temperature-dependent. Seasonal Zika occurrence was evaluated in 9 locations representing different climatic suitability for the vector. Data of diary temperatures were extracted and included in the model...
February 19, 2018: Revista Panamericana de Salud Pública, Pan American Journal of Public Health
L M Viljoen, L Hemerik, J Molenaar
The basic reproduction ratio, R0 , is a fundamental concept in epidemiology. It is defined as the total number of secondary infections brought on by a single primary infection, in a totally susceptible population. The value of R0 indicates whether a starting epidemic reaches a considerable part of the population and causes a lot of damage, or whether it remains restricted to a relatively small number of individuals. To calculate R0 one has to evaluate an integral that ranges over the duration of the infection of the host...
February 19, 2018: Acta Biotheoretica
Guirong Liu, Zhimei Liu, Zhen Jin
We establish an SIS-UAU model to present the dynamics of epidemic and information spreading in overlay networks. The overlay network is represented by two layers: one where the dynamics of the epidemic evolves and another where the information spreads. We theoretically derive the explicit formulas for the basic reproduction number of awareness R 0 a by analyzing the self-consistent equation and the basic reproduction number of disease R 0 d by using the next generation matrix. The formula of R 0 d shows that the effect of awareness can reduce the basic reproduction number of disease...
February 13, 2018: Journal of Theoretical Biology
Gayane Poghotanyan, Zhilan Feng, John W Glasser, Andrew N Hill
The basic reproduction number ([Formula: see text]) can be considerably higher in an SIR model with heterogeneous mixing compared to that from a corresponding model with homogeneous mixing. For example, in the case of measles, mumps and rubella in San Diego, CA, Glasser et al. (Lancet Infect Dis 16(5):599-605, 2016. ), reported an increase of 70% in [Formula: see text] when heterogeneity was accounted for. Meta-population models with simple heterogeneous mixing functions, e...
February 14, 2018: Journal of Mathematical Biology
Jose L Gonzales, Guus Koch, Armin R W Elbers, Jeanet A van der Goot
The transmissibility of the H7N1 highly pathogenic avian influenza virus (HPAIV), which caused a large epidemic in commercial poultry in Italy in 1999-2000, was studied in chickens and compared with that of the low pathogenic precursor virus (LPAIV). Group transmission experiments using the HPAIV were executed to estimate the infectious period (IP), the transmission parameter (β) and the basic reproduction number (R0). These estimates were then compared with those reported for the LPAIV. The estimated β and R0 were similar for both viruses, whilst the IP of the LPAIV was longer than that of the HPAIV...
February 2018: Veterinary Journal
Valentina Costantino, Mohana P Kunasekaran, Abrar A Chughtai, Chandini R MacIntyre
Background: Globally eradicated in 1980, smallpox is listed as a category A bioterrorism agent. If smallpox were to re-emerge, it may be due to an act of bioterrorism or a laboratory accident, and the impact is likely to be severe. Preparedness against smallpox is subject to more uncertainty than other infectious diseases because it is eradicated, there is uncertainty about population immunity, and the current global health workforce has no practical experience or living memory of smallpox...
February 7, 2018: Military Medicine
Sam H Farrell, Roy M Anderson
BACKGROUND: The success of mass drug administration programmes targeting the soil-transmitted helminths and schistosome parasites is in part dependent on compliance to treatment at sequential rounds of mass drug administration (MDA). The impact of MDA is vulnerable to systematic non-compliance, defined as a portion of the eligible population remaining untreated over successive treatment rounds. The impact of systematic non-compliance on helminth transmission dynamics - and thereby on the number of treatment rounds required to interrupt transmission - is dependent on the parasitic helminth being targeted by MDA...
January 31, 2018: Parasites & Vectors
Y Li, J Q Tan, Z Y Mai, D Z Yang
Objective: Explore the value of anti-Müllerian hormone (AMH) in predicting pregnant outcomes of polycystic ovary syndrome (PCOS) patients undergone assisted reproductive technology. Methods: The study totally recruited 1 697 patients who underwent the first in vitro fertilization (IVF) or intracytoplasmic sperm injection (ICSI) cycle in Sun Yat-sen Memorial Hospital from the January 2014 to December 2015. The patients were divided into two groups based on the age<35 (n=758) and ≥35 years old (n=939) , compare the basic data and pregnant outcomes of controlled ovarian hyerstimulation...
January 25, 2018: Zhonghua Fu Chan Ke za Zhi
Sarder Mohammed Asaduzzaman, Junling Ma, P van den Driessche
To determine the cross-immunity between influenza strains, we design a novel statistical method, which uses a theoretical model and clinical data on attack rates and vaccine efficacy among school children for two seasons after the 1968 A/H3N2 influenza pandemic. This model incorporates the distribution of susceptibility and the dependence of cross-immunity on the antigenic distance of drifted strains. We find that the cross-immunity between an influenza strain and the mutant that causes the next epidemic is 88%...
January 25, 2018: Bulletin of Mathematical Biology
Awang Hazmi Awang-Junaidi, Ali Honaramooz
Background: Gonocytes give rise to spermatogonial stem cells, and thereby play an essential role in establishing spermatogenesis. Optimized culture conditions for gonocytes provide an opportunity for their study and in vitro manipulation for potential application in reproductive technologies. Using six experiments in a step-wise design, we examined the effects of several culture conditions on the maintenance, proliferation, and colony formation of porcine gonocytes. Testis cells from neonatal piglets were cultured for 7 d in DMEM supplemented with 10% fetal bovine serum...
2018: Journal of Animal Science and Biotechnology
Wencel Valega-Mackenzie, Karen R Ríos-Soto
Zika virus (ZIKV) is a vector-borne disease that has rapidly spread during the year 2016 in more than 50 countries around the world. If a woman is infected during pregnancy, the virus can cause severe birth defects and brain damage in their babies. The virus can be transmitted through the bites of infected mosquitoes as well as through direct contact from human to human (e.g., sexual contact and blood transfusions). As an intervention for controlling the spread of the disease, we study a vaccination model for preventing Zika infections...
January 22, 2018: Bulletin of Mathematical Biology
Wamdaogo M Guelbéogo, Bronner Pamplona Gonçalves, Lynn Grignard, John Bradley, Samuel S Serme, Joel Hellewell, Kjerstin Lanke, Soumanaba Zongo, Nuno Sepúlveda, Issiaka Soulama, Dimitri W Wangrawa, Laith Yakob, N'Falé Sagnon, Teun Bousema, Chris Drakeley
Variation in biting frequency by Anopheles mosquitoes can explain some of the heterogeneity in malaria transmission in endemic areas. In this study in Burkina Faso, we assessed natural exposure to mosquitoes by matching the genotype of blood meals from 1066 mosquitoes with blood from residents of local households. We observed that the distribution of mosquito bites exceeded the Pareto rule (20/80) in two of the three surveys performed (20/85, 76, and 96) and, at its most pronounced, is estimated to have profound epidemiological consequences, inflating the basic reproduction number of malaria by 8-fold...
January 23, 2018: ELife
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