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Sample records for affect infection dynamics

  1. Viral kinetics and exhaled droplet size affect indoor transmission dynamics of influenza infection.

    PubMed

    Chen, S C; Chio, C P; Jou, L J; Liao, C M

    2009-10-01

    The purpose of this paper was to investigate the effects of viral kinetics and exhaled droplet size on indoor transmission dynamics of influenza infection. The target cell-limited model with delayed virus production was adopted to strengthen the inner mechanisms of virus infection on human epithelial cell. The particle number and volume involved in the viral kinetics were linked with Wells-Riley mathematical equation to quantify the infection risk. We investigated population dynamics in a specific elementary school by using the seasonal susceptible - exposed - infected - recovery (SEIR) model. We found that exhaled pulmonary bioaerosol of sneeze (particle diameter <10 microm) have 10(2)-fold estimate higher than that of cough. Sneeze and cough caused risk probabilities range from 0.075 to 0.30 and 0.076, respectively; whereas basic reproduction numbers (R(0)) estimates range from 4 to 17 for sneeze and nearly 4 for cough, indicating sneeze-posed higher infection risk. The viral kinetics and exhaled droplet size for sneeze affect indoor transmission dynamics of influenza infection since date post-infection 1-7. This study provides direct mechanistic support that indoor influenza virus transmission can be characterized by viral kinetics in human upper respiratory tracts that are modulated by exhaled droplet size. Practical Implications This paper provides a predictive model that can integrate the influenza viral kinetics (target cell-limited model), indoor aerosol transmission potential (Wells-Riley mathematical equation), and population dynamic model [susceptible - exposed - infected - recovery (SEIR) model] in a proposed susceptible population. Viral kinetics expresses the competed results of human immunity ability with influenza virus generation. By linking the viral kinetics and different exposure parameters and environmental factors in a proposed school setting with five age groups, the influenza infection risk can be estimated. On the other hand, we implicated

  2. Viral kinetics and exhaled droplet size affect indoor transmission dynamics of influenza infection.

    PubMed

    Chen, S C; Chio, C P; Jou, L J; Liao, C M

    2009-10-01

    The purpose of this paper was to investigate the effects of viral kinetics and exhaled droplet size on indoor transmission dynamics of influenza infection. The target cell-limited model with delayed virus production was adopted to strengthen the inner mechanisms of virus infection on human epithelial cell. The particle number and volume involved in the viral kinetics were linked with Wells-Riley mathematical equation to quantify the infection risk. We investigated population dynamics in a specific elementary school by using the seasonal susceptible - exposed - infected - recovery (SEIR) model. We found that exhaled pulmonary bioaerosol of sneeze (particle diameter <10 microm) have 10(2)-fold estimate higher than that of cough. Sneeze and cough caused risk probabilities range from 0.075 to 0.30 and 0.076, respectively; whereas basic reproduction numbers (R(0)) estimates range from 4 to 17 for sneeze and nearly 4 for cough, indicating sneeze-posed higher infection risk. The viral kinetics and exhaled droplet size for sneeze affect indoor transmission dynamics of influenza infection since date post-infection 1-7. This study provides direct mechanistic support that indoor influenza virus transmission can be characterized by viral kinetics in human upper respiratory tracts that are modulated by exhaled droplet size. Practical Implications This paper provides a predictive model that can integrate the influenza viral kinetics (target cell-limited model), indoor aerosol transmission potential (Wells-Riley mathematical equation), and population dynamic model [susceptible - exposed - infected - recovery (SEIR) model] in a proposed susceptible population. Viral kinetics expresses the competed results of human immunity ability with influenza virus generation. By linking the viral kinetics and different exposure parameters and environmental factors in a proposed school setting with five age groups, the influenza infection risk can be estimated. On the other hand, we implicated

  3. Dynamic Indices of Methamphetamine Dependence and HIV Infection Predict Fluctuations in Affective Distress: A Five-year Longitudinal Analysis

    PubMed Central

    Montoya, Jessica L.; Umlauf, Anya; Abramson, Ian; Badiee, Jayraan; Woods, Steven Paul; Atkinson, J. Hampton; Grant, Igor; Moore, David J.

    2013-01-01

    Background Methamphetamine (METH) use and human immunodeficiency virus (HIV) infection are highly comorbid, and both are associated with increased prevalence of affective distress. Delineating the trajectory of affective distress in the context of METH dependence and HIV infection is important given the implications for everyday functional impairment, adverse health behaviors, and increased risk for adverse health outcomes. Methods We conducted a five-year longitudinal investigation involving 133 METH-dependent (74 HIV seropositive) and 163 non-METH-dependent (90 HIV seropositive) persons to examine both long-standing patterns and transient changes in affective distress. Mixed-effect regression models with random subject-specific slopes and intercepts evaluated the effect of METH dependence, HIV serostatus, and related variables on affective distress, as measured by the Profile of Mood States. Results Transient changes in affective distress were found to be greater among those with a diagnosis of current MDD, briefer durations of abstinence from METH, and higher quantity of METH consumed. Weak associations were observed among static (time-independent predictors) covariates and long-standing patterns in affective distress. Limitations Study lacked data pertaining to the participants’ involvement in METH treatment and relied on respondent-driven sampling. Conclusions Our longitudinal investigation of the trajectory of affective distress indicated that specific and dynamic indices of current METH use were associated with greater transient changes in mood. In the evaluation and treatment of affective distress, recency and quantity of current METH use are important to consider given their association with heightened affective distress and mood instability over time. PMID:24012068

  4. Affective Dynamics in Psychopathology

    PubMed Central

    Trull, Timothy J.; Lane, Sean P.; Koval, Peter; Ebner-Priemer, Ulrich W.

    2016-01-01

    We discuss three varieties of affective dynamics (affective instability, emotional inertia, and emotional differentiation). In each case, we suggest how these affective dynamics should be operationalized and measured in daily life using time-intensive methods, like ecological momentary assessment or ambulatory assessment, and recommend time-sensitive analyses that take into account not only the variability but also the temporal dependency of reports. Studies that explore how these affective dynamics are associated with psychological disorders and symptoms are reviewed, and we emphasize that these affective processes are within a nexus of other components of emotion regulation.

  5. Dynamic Synchronization of Teacher-Students Affection in Affective Instruction

    ERIC Educational Resources Information Center

    Zhang, Wenhai; Lu, Jiamei

    2011-01-01

    Based on Bower's affective network theory, the article links the dynamic analysis of affective factors in affective instruction, and presents affective instruction strategic of dynamic synchronization between teacher and students to implement the best ideal mood that promotes students' cognition and affection together. In the process of teaching,…

  6. Spatiotemporal dynamics of HIV infection

    NASA Astrophysics Data System (ADS)

    Strain, Matthew Carl

    Mathematical models of the dynamics of infection with the human immunodeficiency virus (HIV) have contributed to tremendous advances over the past 20 years. This thesis extends this previous work by exploring the importance of spatial heterogeneity in HIV infection both in vitro and in vivo in patients treated with highly-active antiretroviral therapy. Viral infections propagate locally in space, yet HIV infection has been widely regarded as equilibrated over the entire body of an infected patient. This dissertation constructs and explores a cellular automata model of viral spread at the cellular level. Coupling the automata to a blood compartment represented by a differential equation leads to a whole-body model of HIV infection that explicitly includes spatial effects at both the cellular and tissue levels. These models are tested by comparison with experimental data. A central prediction of the spatial model is that, due to competition between Brownian motion and viral lability, HIV infectivity increases with target cell density. This production is verified in a series of in vitro experiments in cell culture. The predicted independence of inhibitory concentrations of antiretoviral agents is verified for nevirapine, but azidothymidine inhibits HIV replication less efficiently in more dense cultures. These in vitro results suggest that systems allowing cell concentrations closer to tissue densities would better reflect virus replication kinetics, although standard measures of relative drug susceptibility may accurately reflect in vivo conditions. The coupled spatial model of in vivo dynamics is compared with novel mathematical analysis of experiments in HIV-infected patients. These analyses indicate that HIV DNA provides a useful marker of the size of long-lived cellular reservoirs of HIV. Levels of HIV DNA in peripheral blood are predictive of the average rate of residual virus production after years of treatment, regardless of whether patients initiate therapy

  7. Spatiotemporal modelling of viral infection dynamics

    NASA Astrophysics Data System (ADS)

    Beauchemin, Catherine

    Viral kinetics have been studied extensively in the past through the use of ordinary differential equations describing the time evolution of the diseased state in a spatially well-mixed medium. However, emerging spatial structures such as localized populations of dead cells might affect the spread of infection, similar to the manner in which a counter-fire can stop a forest fire from spreading. In the first phase of the project, a simple two-dimensional cellular automaton model of viral infections was developed. It was validated against clinical immunological data for uncomplicated influenza A infections and shown to be accurate enough to adequately model them. In the second phase of the project, the simple two-dimensional cellular automaton model was used to investigate the effects of relaxing the well-mixed assumption on viral infection dynamics. It was shown that grouping the initially infected cells into patches rather than distributing them uniformly on the grid reduced the infection rate as only cells on the perimeter of the patch have healthy neighbours to infect. Use of a local epithelial cell regeneration rule where dead cells are replaced by healthy cells when an immediate neighbour divides was found to result in more extensive damage of the epithelium and yielded a better fit to experimental influenza A infection data than a global regeneration rule based on division rate of healthy cell. Finally, the addition of immune cell at the site of infection was found to be a better strategy at low infection levels, while addition at random locations on the grid was the better strategy at high infection level. In the last project, the movement of T cells within lymph nodes in the absence of antigen, was investigated. Based on individual T cell track data captured by two-photon microscopy experiments in vivo, a simple model was proposed for the motion of T cells. This is the first step towards the implementation of a more realistic spatiotemporal model of HIV than

  8. Dynamic musical communication of core affect

    PubMed Central

    Flaig, Nicole K.; Large, Edward W.

    2013-01-01

    Is there something special about the way music communicates feelings? Theorists since Meyer (1956) have attempted to explain how music could stimulate varied and subtle affective experiences by violating learned expectancies, or by mimicking other forms of social interaction. Our proposal is that music speaks to the brain in its own language; it need not imitate any other form of communication. We review recent theoretical and empirical literature, which suggests that all conscious processes consist of dynamic neural events, produced by spatially dispersed processes in the physical brain. Intentional thought and affective experience arise as dynamical aspects of neural events taking place in multiple brain areas simultaneously. At any given moment, this content comprises a unified “scene” that is integrated into a dynamic core through synchrony of neuronal oscillations. We propose that (1) neurodynamic synchrony with musical stimuli gives rise to musical qualia including tonal and temporal expectancies, and that (2) music-synchronous responses couple into core neurodynamics, enabling music to directly modulate core affect. Expressive music performance, for example, may recruit rhythm-synchronous neural responses to support affective communication. We suggest that the dynamic relationship between musical expression and the experience of affect presents a unique opportunity for the study of emotional experience. This may help elucidate the neural mechanisms underlying arousal and valence, and offer a new approach to exploring the complex dynamics of the how and why of emotional experience. PMID:24672492

  9. Dynamic musical communication of core affect.

    PubMed

    Flaig, Nicole K; Large, Edward W

    2014-01-01

    Is there something special about the way music communicates feelings? Theorists since Meyer (1956) have attempted to explain how music could stimulate varied and subtle affective experiences by violating learned expectancies, or by mimicking other forms of social interaction. Our proposal is that music speaks to the brain in its own language; it need not imitate any other form of communication. We review recent theoretical and empirical literature, which suggests that all conscious processes consist of dynamic neural events, produced by spatially dispersed processes in the physical brain. Intentional thought and affective experience arise as dynamical aspects of neural events taking place in multiple brain areas simultaneously. At any given moment, this content comprises a unified "scene" that is integrated into a dynamic core through synchrony of neuronal oscillations. We propose that (1) neurodynamic synchrony with musical stimuli gives rise to musical qualia including tonal and temporal expectancies, and that (2) music-synchronous responses couple into core neurodynamics, enabling music to directly modulate core affect. Expressive music performance, for example, may recruit rhythm-synchronous neural responses to support affective communication. We suggest that the dynamic relationship between musical expression and the experience of affect presents a unique opportunity for the study of emotional experience. This may help elucidate the neural mechanisms underlying arousal and valence, and offer a new approach to exploring the complex dynamics of the how and why of emotional experience. PMID:24672492

  10. HIV Infection Seems to Affect Nervous System

    MedlinePlus

    ... is a clinical fellow in the department of neurology at the University of California, San Francisco (UCSF). " ... early [HIV] infection." Valcour is a professor of neurology at UCSF. "Additionally, the ubiquity of symptoms in ...

  11. Mitochondrial dynamics and viral infections: A close nexus.

    PubMed

    Khan, Mohsin; Syed, Gulam Hussain; Kim, Seong-Jun; Siddiqui, Aleem

    2015-10-01

    Viruses manipulate cellular machinery and functions to subvert intracellular environment conducive for viral proliferation. They strategically alter functions of the multitasking mitochondria to influence energy production, metabolism, survival, and immune signaling. Mitochondria either occur as heterogeneous population of individual organelles or large interconnected tubular network. The mitochondrial network is highly susceptible to physiological and environmental insults, including viral infections, and is dynamically maintained by mitochondrial fission and fusion. Mitochondrial dynamics in tandem with mitochondria-selective autophagy 'mitophagy' coordinates mitochondrial quality control and homeostasis. Mitochondrial dynamics impacts cellular homeostasis, metabolism, and innate-immune signaling, and thus can be major determinant of the outcome of viral infections. Herein, we review how mitochondrial dynamics is affected during viral infections and how this complex interplay benefits the viral infectious process and associated diseases.

  12. How should environmental stress affect the population dynamics of disease?

    USGS Publications Warehouse

    Lafferty, Kevin D.; Holt, Robert D.

    2003-01-01

    We modelled how stress affects the population dynamics of infectious disease. We were specifically concerned with stress that increased susceptibility of uninfected hosts when exposed to infection. If such stresses also reduced resources, fecundity and/or survivorship, there was a reduction in the host carrying capacity. This lowered the contact between infected and uninfected hosts, thereby decreasing transmission. In addition, stress that increased parasite mortality decreased disease. The opposing effects of stress on disease dynamics made it difficult to predict the response of disease to environmental stress. We found analytical solutions with negative, positive, convex and concave associations between disease and stress. Numerical simulations with randomly generated parameter values suggested that the impact of host-specific diseases generally declined with stress while the impact of non-specific (or open) diseases increased with stress. These results help clarify predictions about the interaction between environmental stress and disease in natural populations.

  13. Global research priorities for infections that affect the nervous system

    PubMed Central

    John, Chandy C.; Carabin, Hélène; Montano, Silvia M.; Bangirana, Paul; Zunt, Joseph R.; Peterson, Phillip K.

    2015-01-01

    Infections that cause significant nervous system morbidity globally include viral (for example, HIV, rabies, Japanese encephalitis virus, herpes simplex virus, varicella zoster virus, cytomegalovirus, dengue virus and chikungunya virus), bacterial (for example, tuberculosis, syphilis, bacterial meningitis and sepsis), fungal (for example, cryptococcal meningitis) and parasitic (for example, malaria, neurocysticercosis, neuroschistosomiasis and soil-transmitted helminths) infections. The neurological, cognitive, behavioural or mental health problems caused by the infections probably affect millions of children and adults in low- and middle-income countries. However, precise estimates of morbidity are lacking for most infections, and there is limited information on the pathogenesis of nervous system injury in these infections. Key research priorities for infection-related nervous system morbidity include accurate estimates of disease burden; point-of-care assays for infection diagnosis; improved tools for the assessment of neurological, cognitive and mental health impairment; vaccines and other interventions for preventing infections; improved understanding of the pathogenesis of nervous system disease in these infections; more effective methods to treat and prevent nervous system sequelae; operations research to implement known effective interventions; and improved methods of rehabilitation. Research in these areas, accompanied by efforts to implement promising technologies and therapies, could substantially decrease the morbidity and mortality of infections affecting the nervous system in low- and middle-income countries. PMID:26580325

  14. Global research priorities for infections that affect the nervous system.

    PubMed

    John, Chandy C; Carabin, Hélène; Montano, Silvia M; Bangirana, Paul; Zunt, Joseph R; Peterson, Phillip K

    2015-11-19

    Infections that cause significant nervous system morbidity globally include viral (for example, HIV, rabies, Japanese encephalitis virus, herpes simplex virus, varicella zoster virus, cytomegalovirus, dengue virus and chikungunya virus), bacterial (for example, tuberculosis, syphilis, bacterial meningitis and sepsis), fungal (for example, cryptococcal meningitis) and parasitic (for example, malaria, neurocysticercosis, neuroschistosomiasis and soil-transmitted helminths) infections. The neurological, cognitive, behavioural or mental health problems caused by the infections probably affect millions of children and adults in low- and middle-income countries. However, precise estimates of morbidity are lacking for most infections, and there is limited information on the pathogenesis of nervous system injury in these infections. Key research priorities for infection-related nervous system morbidity include accurate estimates of disease burden; point-of-care assays for infection diagnosis; improved tools for the assessment of neurological, cognitive and mental health impairment; vaccines and other interventions for preventing infections; improved understanding of the pathogenesis of nervous system disease in these infections; more effective methods to treat and prevent nervous system sequelae; operations research to implement known effective interventions; and improved methods of rehabilitation. Research in these areas, accompanied by efforts to implement promising technologies and therapies, could substantially decrease the morbidity and mortality of infections affecting the nervous system in low- and middle-income countries.

  15. Global research priorities for infections that affect the nervous system.

    PubMed

    John, Chandy C; Carabin, Hélène; Montano, Silvia M; Bangirana, Paul; Zunt, Joseph R; Peterson, Phillip K

    2015-11-19

    Infections that cause significant nervous system morbidity globally include viral (for example, HIV, rabies, Japanese encephalitis virus, herpes simplex virus, varicella zoster virus, cytomegalovirus, dengue virus and chikungunya virus), bacterial (for example, tuberculosis, syphilis, bacterial meningitis and sepsis), fungal (for example, cryptococcal meningitis) and parasitic (for example, malaria, neurocysticercosis, neuroschistosomiasis and soil-transmitted helminths) infections. The neurological, cognitive, behavioural or mental health problems caused by the infections probably affect millions of children and adults in low- and middle-income countries. However, precise estimates of morbidity are lacking for most infections, and there is limited information on the pathogenesis of nervous system injury in these infections. Key research priorities for infection-related nervous system morbidity include accurate estimates of disease burden; point-of-care assays for infection diagnosis; improved tools for the assessment of neurological, cognitive and mental health impairment; vaccines and other interventions for preventing infections; improved understanding of the pathogenesis of nervous system disease in these infections; more effective methods to treat and prevent nervous system sequelae; operations research to implement known effective interventions; and improved methods of rehabilitation. Research in these areas, accompanied by efforts to implement promising technologies and therapies, could substantially decrease the morbidity and mortality of infections affecting the nervous system in low- and middle-income countries. PMID:26580325

  16. The Dynamics of Natural Plasmodium falciparum Infections

    PubMed Central

    Felger, Ingrid; Maire, Martin; Bretscher, Michael T.; Falk, Nicole; Tiaden, André; Sama, Wilson; Beck, Hans-Peter; Owusu-Agyei, Seth; Smith, Thomas A.

    2012-01-01

    Background Natural immunity to Plasmodium falciparum has been widely studied, but its effects on parasite dynamics are poorly understood. Acquisition and clearance rates of untreated infections are key elements of the dynamics of malaria, but estimating these parameters is challenging because of frequent super-infection and imperfect detectability of parasites. Consequently, information on effects of host immune status or age on infection dynamics is fragmentary. Methods An age-stratified cohort of 347 individuals from Northern Ghana was sampled six times at 2 month intervals. High-throughput capillary electrophoresis was used to genotype the msp-2 locus of all P. falciparum infections detected by PCR. Force of infection (FOI) and duration were estimated for each age group using an immigration-death model that allows for imperfect detection of circulating parasites. Results Allowing for imperfect detection substantially increased estimates of FOI and duration. Effects of naturally acquired immunity on the FOI and duration would be reflected in age dependence in these indices, but in our cohort data FOI tended to increase with age in children. Persistence of individual parasite clones was characteristic of all age-groups. Duration peaked in 5–9 year old children (average duration 319 days, 95% confidence interval 318;320). Conclusions The main age-dependence is on parasite densities, with only small age-variations in the FOI and persistence of infections. This supports the hypothesis that acquired immunity controls transmission mainly by limiting blood-stage parasite densities rather than changing rates of acquisition or clearance of infections. PMID:23029082

  17. Viral dynamics in hepatitis B virus infection.

    PubMed Central

    Nowak, M A; Bonhoeffer, S; Hill, A M; Boehme, R; Thomas, H C; McDade, H

    1996-01-01

    Treatment of chronic hepatitis B virus (HBV) infections with the reverse transcriptase inhibitor lamivudine leads to a rapid decline in plasma viremia and provides estimates for crucial kinetic constants of HBV replication. We find that in persistently infected patients, HBV particles are cleared from the plasma with a half-life of approximately 1.0 day, which implies a 50% daily turnover of the free virus population. Total viral release into the periphery is approximately 10(11) virus particles per day. Although we have no direct measurement of the infected cell mass, we can estimate the turnover rate of these cells in two ways: (i) by comparing the rate of viral production before and after therapy or (ii) from the decline of hepatitis B antigen during treatment. These two independent methods give equivalent results: we find a wide distribution of half-lives for virus-producing cells, ranging from 10 to 100 days in different patients, which may reflect differences in rates of lysis of infected cells by immune responses. Our analysis provides a quantitative understanding of HBV replication dynamics in vivo and has implications for the optimal timing of drug treatment and immunotherapy in chronic HBV infection. This study also represents a comparison for recent findings on the dynamics of human immunodeficiency virus (HIV) infection. The total daily production of plasma virus is, on average, higher in chronic HBV carriers than in HIV-infected patients, but the half-life of virus-producing cells is much shorter in HIV. Most strikingly, there is no indication of drug resistance in HBV-infected patients treated for up to 24 weeks. PMID:8633078

  18. Expression of Nucleolin Affects Microtubule Dynamics.

    PubMed

    Gaume, Xavier; Place, Christophe; Delage, Helene; Mongelard, Fabien; Monier, Karine; Bouvet, Philippe

    2016-01-01

    Nucleolin is present in diverse cellular compartments and is involved in a variety of cellular processes from nucleolar structure and function to intracellular trafficking, cell adhesion and migration. Recently, nucleolin has been localized at the mature centriole where it is involved in microtubule nucleation and anchoring. Although this new function of nucleolin linked to microtubule regulation has been identified, the global effects of nucleolin on microtubule dynamics have not been addressed yet. In the present study, we analyzed the roles of nucleolin protein levels on global microtubule dynamics by tracking the EB3 microtubule plus end binding protein in live cells. We have found that during microtubule growth phases, nucleolin affects both the speed and life time of polymerization and by analyzing catastrophe events, we showed that nucleolin reduces catastrophe frequency. This new property of nucleolin was then confirmed in a cold induced microtubule depolymerization experiment in which we have found that cold resistant microtubules were totally destabilized in nucleolin depleted cells. Altogether, our data demonstrate a new function of nucleolin on microtubule stabilization, thus bringing novel insights into understanding the multifunctional properties of nucleolin in healthy and cancer cells. PMID:27309529

  19. Expression of Nucleolin Affects Microtubule Dynamics

    PubMed Central

    Gaume, Xavier; Place, Christophe; Delage, Helene; Mongelard, Fabien; Monier, Karine; Bouvet, Philippe

    2016-01-01

    Nucleolin is present in diverse cellular compartments and is involved in a variety of cellular processes from nucleolar structure and function to intracellular trafficking, cell adhesion and migration. Recently, nucleolin has been localized at the mature centriole where it is involved in microtubule nucleation and anchoring. Although this new function of nucleolin linked to microtubule regulation has been identified, the global effects of nucleolin on microtubule dynamics have not been addressed yet. In the present study, we analyzed the roles of nucleolin protein levels on global microtubule dynamics by tracking the EB3 microtubule plus end binding protein in live cells. We have found that during microtubule growth phases, nucleolin affects both the speed and life time of polymerization and by analyzing catastrophe events, we showed that nucleolin reduces catastrophe frequency. This new property of nucleolin was then confirmed in a cold induced microtubule depolymerization experiment in which we have found that cold resistant microtubules were totally destabilized in nucleolin depleted cells. Altogether, our data demonstrate a new function of nucleolin on microtubule stabilization, thus bringing novel insights into understanding the multifunctional properties of nucleolin in healthy and cancer cells. PMID:27309529

  20. HIV Infection Affects Streptococcus mutans Levels, but Not Genotypes

    PubMed Central

    Liu, G.; Saxena, D.; Chen, Z.; Norman, R.G.; Phelan, J.A.; Laverty, M.; Fisch, G.S.; Corby, P.M.; Abrams, W.; Malamud, D.; Li, Y.

    2012-01-01

    We report a clinical study that examines whether HIV infection affects Streptococcus mutans colonization in the oral cavity. Whole stimulated saliva samples were collected from 46 HIV-seropositive individuals and 69 HIV-seronegative control individuals. The level of S. mutans colonization was determined by conventional culture methods. The genotype of S. mutans was compared between 10 HIV-positive individuals before and after highly active antiretroviral therapy (HAART) and 10 non-HIV-infected control individuals. The results were analyzed against viral load, CD4+ and CD8+ T-cell counts, salivary flow rate, and caries status. We observed that S. mutans levels were higher in HIV-infected individuals than in the non-HIV-infected control individuals (p = 0.013). No significant differences in S. mutans genotypes were found between the two groups over the six-month study period, even after HAART. There was a bivariate linear relationship between S. mutans levels and CD8+ counts (r = 0.412; p = 0.007), but not between S. mutans levels and either CD4+ counts or viral load. Furthermore, compared with non-HIV-infected control individuals, HIV-infected individuals experienced lower salivary secretion (p = 0.009) and a positive trend toward more decayed tooth surfaces (p = 0.027). These findings suggest that HIV infection can have a significant effect on the level of S. mutans, but not genotypes. PMID:22821240

  1. We Are All Affected: Considering the Recovery of HIV/AIDS Infected and Affected Children

    ERIC Educational Resources Information Center

    Nelson, Carla

    2008-01-01

    This essay acknowledges that the HIV/AIDS pandemic has created entire communities for whom loss has become a common and a shared experience. As a result of this impact of HIV/AIDS, several questions surface. However, the one question upon which this essay focuses is, "What type of environment is required for children infected and affected by…

  2. Modeling the Dynamics of Plasmodium vivax Infection and Hypnozoite Reactivation In Vivo

    PubMed Central

    Adekunle, Adeshina I.; Pinkevych, Mykola; McGready, Rose; Luxemburger, Christine; White, Lisa J.; Nosten, François; Cromer, Deborah; Davenport, Miles P.

    2015-01-01

    The dynamics of Plasmodium vivax infection is characterized by reactivation of hypnozoites at varying time intervals. The relative contribution of new P. vivax infection and reactivation of dormant liver stage hypnozoites to initiation of blood stage infection is unclear. In this study, we investigate the contribution of new inoculations of P. vivax sporozoites to primary infection versus reactivation of hypnozoites by modeling the dynamics of P. vivax infection in Thailand in patients receiving treatment for either blood stage infection alone (chloroquine), or the blood and liver stages of infection (chloroquine + primaquine). In addition, we also analysed rates of infection in a study in Papua New Guinea (PNG) where patients were treated with either artesunate, or artesunate + primaquine. Our results show that up to 96% of the P. vivax infection is due to hypnozoite reactivation in individuals living in endemic areas in Thailand. Similar analysis revealed the around 70% of infections in the PNG cohort were due to hypnozoite reactivation. We show how the age of the cohort, primaquine drug failure, and seasonality may affect estimates of the ratio of primary P. vivax infection to hypnozoite reactivation. Modeling of P. vivax primary infection and hypnozoite reactivation provides important insights into infection dynamics, and suggests that 90–96% of blood stage infections arise from hypnozoite reactivation. Major differences in infection kinetics between Thailand and PNG suggest the likelihood of drug failure in PNG. PMID:25780913

  3. Interactions of warming and exposure affect susceptibility to parasite infection in a temperate fish species.

    PubMed

    Sheath, Danny J; Andreou, Demetra; Britton, J Robert

    2016-09-01

    Predicting how elevated temperatures from climate change alter host-parasite interactions requires understandings of how warming affects host susceptibility and parasite virulence. Here, the effect of elevated water temperature and parasite exposure level was tested on parasite prevalence, abundance and burden, and on fish growth, using Pomphorhynchus laevis and its fish host Squalius cephalus. At 60 days post-exposure, prevalence was higher at the elevated temperature (22 °C) than ambient temperature (18 °C), with infections achieved at considerably lower levels of exposure. Whilst parasite number was significantly higher in infected fish at 22 °C, both mean parasite weight and parasite burden was significantly higher at 18 °C. There were, however, no significant relationships between fish growth rate and temperature, parasite exposure, and the infection parameters. Thus, whilst elevated temperature significantly influenced parasite infection rates, it also impacted parasite development rates, suggesting warming could have complex implications for parasite dynamics and host resistance.

  4. Dynamic artificial neural networks with affective systems.

    PubMed

    Schuman, Catherine D; Birdwell, J Douglas

    2013-01-01

    Artificial neural networks (ANNs) are processors that are trained to perform particular tasks. We couple a computational ANN with a simulated affective system in order to explore the interaction between the two. In particular, we design a simple affective system that adjusts the threshold values in the neurons of our ANN. The aim of this paper is to demonstrate that this simple affective system can control the firing rate of the ensemble of neurons in the ANN, as well as to explore the coupling between the affective system and the processes of long term potentiation (LTP) and long term depression (LTD), and the effect of the parameters of the affective system on its performance. We apply our networks with affective systems to a simple pole balancing example and briefly discuss the effect of affective systems on network performance.

  5. Alternative prey use affects helminth parasite infections in grey wolves.

    PubMed

    Friesen, Olwyn C; Roth, James D

    2016-09-01

    Predators affect prey populations not only through direct predation, but also by acting as definitive hosts for their parasites and completing parasite life cycles. Understanding the affects of parasitism on prey population dynamics requires knowing how their predators' parasite community is affected by diet and prey availability. Ungulates, such as moose (Alces americanus) and white-tailed deer (Odocoileus virginianus), are often important prey for wolves (Canis lupus), but wolves also consume a variety of alternative prey, including beaver (Castor canadensis) and snowshoe hare (Lepus americanus). The use of alternative prey, which may host different or fewer parasites than ungulates, could potentially reduce overall abundance of ungulate parasites within the ecosystem, benefiting both wolves and ungulate hosts. We examined parasites in wolf carcasses from eastern Manitoba and estimated wolf diet using stable isotope analysis. Taeniidae cestodes were present in most wolves (75%), reflecting a diet primarily comprised of ungulates, but nematodes were unexpectedly rare. Cestode abundance was negatively related to the wolf's δ(13) C value, indicating diet affects parasite abundance. Wolves that consumed a higher proportion of beaver and caribou (Rangifer tarandus), estimated using Bayesian mixing models, had lower cestode abundance, suggesting the use of these alternative prey can reduce parasite loads. Long-term consumption of beavers may lower the abundance of adult parasites in wolves, eventually lowering parasite density in the region and ultimately benefiting ungulates that serve as intermediate hosts. Thus, alternative prey can affect both predator-prey and host-parasite interactions and potentially affect food web dynamics.

  6. Alternative prey use affects helminth parasite infections in grey wolves.

    PubMed

    Friesen, Olwyn C; Roth, James D

    2016-09-01

    Predators affect prey populations not only through direct predation, but also by acting as definitive hosts for their parasites and completing parasite life cycles. Understanding the affects of parasitism on prey population dynamics requires knowing how their predators' parasite community is affected by diet and prey availability. Ungulates, such as moose (Alces americanus) and white-tailed deer (Odocoileus virginianus), are often important prey for wolves (Canis lupus), but wolves also consume a variety of alternative prey, including beaver (Castor canadensis) and snowshoe hare (Lepus americanus). The use of alternative prey, which may host different or fewer parasites than ungulates, could potentially reduce overall abundance of ungulate parasites within the ecosystem, benefiting both wolves and ungulate hosts. We examined parasites in wolf carcasses from eastern Manitoba and estimated wolf diet using stable isotope analysis. Taeniidae cestodes were present in most wolves (75%), reflecting a diet primarily comprised of ungulates, but nematodes were unexpectedly rare. Cestode abundance was negatively related to the wolf's δ(13) C value, indicating diet affects parasite abundance. Wolves that consumed a higher proportion of beaver and caribou (Rangifer tarandus), estimated using Bayesian mixing models, had lower cestode abundance, suggesting the use of these alternative prey can reduce parasite loads. Long-term consumption of beavers may lower the abundance of adult parasites in wolves, eventually lowering parasite density in the region and ultimately benefiting ungulates that serve as intermediate hosts. Thus, alternative prey can affect both predator-prey and host-parasite interactions and potentially affect food web dynamics. PMID:27155132

  7. Effects of Infection on Honey Bee Population Dynamics: A Model

    PubMed Central

    Betti, Matt I.; Wahl, Lindi M.; Zamir, Mair

    2014-01-01

    We propose a model that combines the dynamics of the spread of disease within a bee colony with the underlying demographic dynamics of the colony to determine the ultimate fate of the colony under different scenarios. The model suggests that key factors in the survival or collapse of a honey bee colony in the face of an infection are the rate of transmission of the infection and the disease-induced death rate. An increase in the disease-induced death rate, which can be thought of as an increase in the severity of the disease, may actually help the colony overcome the disease and survive through winter. By contrast, an increase in the transmission rate, which means that bees are being infected at an earlier age, has a drastic deleterious effect. Another important finding relates to the timing of infection in relation to the onset of winter, indicating that in a time interval of approximately 20 days before the onset of winter the colony is most affected by the onset of infection. The results suggest further that the age of recruitment of hive bees to foraging duties is a good early marker for the survival or collapse of a honey bee colony in the face of infection, which is consistent with experimental evidence but the model provides insight into the underlying mechanisms. The most important result of the study is a clear distinction between an exposure of the honey bee colony to an environmental hazard such as pesticides or insecticides, or an exposure to an infectious disease. The results indicate unequivocally that in the scenarios that we have examined, and perhaps more generally, an infectious disease is far more hazardous to the survival of a bee colony than an environmental hazard that causes an equal death rate in foraging bees. PMID:25329468

  8. Effects of infection on honey bee population dynamics: a model.

    PubMed

    Betti, Matt I; Wahl, Lindi M; Zamir, Mair

    2014-01-01

    We propose a model that combines the dynamics of the spread of disease within a bee colony with the underlying demographic dynamics of the colony to determine the ultimate fate of the colony under different scenarios. The model suggests that key factors in the survival or collapse of a honey bee colony in the face of an infection are the rate of transmission of the infection and the disease-induced death rate. An increase in the disease-induced death rate, which can be thought of as an increase in the severity of the disease, may actually help the colony overcome the disease and survive through winter. By contrast, an increase in the transmission rate, which means that bees are being infected at an earlier age, has a drastic deleterious effect. Another important finding relates to the timing of infection in relation to the onset of winter, indicating that in a time interval of approximately 20 days before the onset of winter the colony is most affected by the onset of infection. The results suggest further that the age of recruitment of hive bees to foraging duties is a good early marker for the survival or collapse of a honey bee colony in the face of infection, which is consistent with experimental evidence but the model provides insight into the underlying mechanisms. The most important result of the study is a clear distinction between an exposure of the honey bee colony to an environmental hazard such as pesticides or insecticides, or an exposure to an infectious disease. The results indicate unequivocally that in the scenarios that we have examined, and perhaps more generally, an infectious disease is far more hazardous to the survival of a bee colony than an environmental hazard that causes an equal death rate in foraging bees.

  9. Thermoregulatory behaviour affects prevalence of chytrid fungal infection in a wild population of Panamanian golden frogs

    PubMed Central

    Richards-Zawacki, Corinne L.

    2010-01-01

    Predicting how climate change will affect disease dynamics requires an understanding of how the environment affects host–pathogen interactions. For amphibians, global declines and extinctions have been linked to a pathogenic chytrid fungus, Batrachochytrium dendrobatidis. Using a combination of body temperature measurements and disease assays conducted before and after the arrival of B. dendrobatidis, this study tested the hypothesis that body temperature affects the prevalence of infection in a wild population of Panamanian golden frogs (Atelopus zeteki). The timing of first detection of the fungus was consistent with that of a wave of epidemic infections spreading south and eastward through Central America. During the epidemic, many golden frogs modified their thermoregulatory behaviour, raising body temperatures above their normal set point. Odds of infection decreased with increasing body temperature, demonstrating that even slight environmental or behavioural changes have the potential to affect an individual's vulnerability to infection. The thermal dependency of the relationship between B. dendrobatidis and its amphibian hosts demonstrates how the progression of an epidemic can be influenced by complex interactions between host and pathogen phenotypes and the environments in which they are found. PMID:19864287

  10. Thermoregulatory behaviour affects prevalence of chytrid fungal infection in a wild population of Panamanian golden frogs.

    PubMed

    Richards-Zawacki, Corinne L

    2010-02-22

    Predicting how climate change will affect disease dynamics requires an understanding of how the environment affects host-pathogen interactions. For amphibians, global declines and extinctions have been linked to a pathogenic chytrid fungus, Batrachochytrium dendrobatidis. Using a combination of body temperature measurements and disease assays conducted before and after the arrival of B. dendrobatidis, this study tested the hypothesis that body temperature affects the prevalence of infection in a wild population of Panamanian golden frogs (Atelopus zeteki). The timing of first detection of the fungus was consistent with that of a wave of epidemic infections spreading south and eastward through Central America. During the epidemic, many golden frogs modified their thermoregulatory behaviour, raising body temperatures above their normal set point. Odds of infection decreased with increasing body temperature, demonstrating that even slight environmental or behavioural changes have the potential to affect an individual's vulnerability to infection. The thermal dependency of the relationship between B. dendrobatidis and its amphibian hosts demonstrates how the progression of an epidemic can be influenced by complex interactions between host and pathogen phenotypes and the environments in which they are found. PMID:19864287

  11. How Resource Phenology Affects Consumer Population Dynamics.

    PubMed

    Bewick, Sharon; Cantrell, R Stephen; Cosner, Chris; Fagan, William F

    2016-02-01

    Climate change drives uneven phenology shifts across taxa, and this can result in changes to the phenological match between interacting species. Shifts in the relative phenology of partner species are well documented, but few studies have addressed the effects of such changes on population dynamics. To explore this, we develop a phenologically explicit model describing consumer-resource interactions. Focusing on scenarios for univoltine insects, we show how changes in resource phenology can be reinterpreted as transformations in the year-to-year recursion relationships defining consumer population dynamics. This perspective provides a straightforward path for interpreting the long-term population consequences of phenology change. Specifically, by relating the outcome of phenological shifts to species traits governing recursion relationships (e.g., consumer fecundity or competitive scenario), we demonstrate how changes in relative phenology can force systems into different dynamical regimes, with major implications for resource management, conservation, and other areas of applied dynamics. PMID:26807744

  12. How Resource Phenology Affects Consumer Population Dynamics.

    PubMed

    Bewick, Sharon; Cantrell, R Stephen; Cosner, Chris; Fagan, William F

    2016-02-01

    Climate change drives uneven phenology shifts across taxa, and this can result in changes to the phenological match between interacting species. Shifts in the relative phenology of partner species are well documented, but few studies have addressed the effects of such changes on population dynamics. To explore this, we develop a phenologically explicit model describing consumer-resource interactions. Focusing on scenarios for univoltine insects, we show how changes in resource phenology can be reinterpreted as transformations in the year-to-year recursion relationships defining consumer population dynamics. This perspective provides a straightforward path for interpreting the long-term population consequences of phenology change. Specifically, by relating the outcome of phenological shifts to species traits governing recursion relationships (e.g., consumer fecundity or competitive scenario), we demonstrate how changes in relative phenology can force systems into different dynamical regimes, with major implications for resource management, conservation, and other areas of applied dynamics.

  13. Co-infection alters population dynamics of infectious disease

    PubMed Central

    Susi, Hanna; Barrès, Benoit; Vale, Pedro F.; Laine, Anna-Liisa

    2015-01-01

    Co-infections by multiple pathogen strains are common in the wild. Theory predicts co-infections to have major consequences for both within- and between-host disease dynamics, but data are currently scarce. Here, using common garden populations of Plantago lanceolata infected by two strains of the pathogen Podosphaera plantaginis, either singly or under co-infection, we find the highest disease prevalence in co-infected treatments both at the host genotype and population levels. A spore-trapping experiment demonstrates that co-infected hosts shed more transmission propagules than singly infected hosts, thereby explaining the observed change in epidemiological dynamics. Our experimental findings are confirmed in natural pathogen populations—more devastating epidemics were measured in populations with higher levels of co-infection. Jointly, our results confirm the predictions made by theoretical and experimental studies for the potential of co-infection to alter disease dynamics across a large host–pathogen metapopulation. PMID:25569306

  14. Co-infection alters population dynamics of infectious disease.

    PubMed

    Susi, Hanna; Barrès, Benoit; Vale, Pedro F; Laine, Anna-Liisa

    2015-01-08

    Co-infections by multiple pathogen strains are common in the wild. Theory predicts co-infections to have major consequences for both within- and between-host disease dynamics, but data are currently scarce. Here, using common garden populations of Plantago lanceolata infected by two strains of the pathogen Podosphaera plantaginis, either singly or under co-infection, we find the highest disease prevalence in co-infected treatments both at the host genotype and population levels. A spore-trapping experiment demonstrates that co-infected hosts shed more transmission propagules than singly infected hosts, thereby explaining the observed change in epidemiological dynamics. Our experimental findings are confirmed in natural pathogen populations-more devastating epidemics were measured in populations with higher levels of co-infection. Jointly, our results confirm the predictions made by theoretical and experimental studies for the potential of co-infection to alter disease dynamics across a large host-pathogen metapopulation.

  15. Co-infection alters population dynamics of infectious disease.

    PubMed

    Susi, Hanna; Barrès, Benoit; Vale, Pedro F; Laine, Anna-Liisa

    2015-01-01

    Co-infections by multiple pathogen strains are common in the wild. Theory predicts co-infections to have major consequences for both within- and between-host disease dynamics, but data are currently scarce. Here, using common garden populations of Plantago lanceolata infected by two strains of the pathogen Podosphaera plantaginis, either singly or under co-infection, we find the highest disease prevalence in co-infected treatments both at the host genotype and population levels. A spore-trapping experiment demonstrates that co-infected hosts shed more transmission propagules than singly infected hosts, thereby explaining the observed change in epidemiological dynamics. Our experimental findings are confirmed in natural pathogen populations-more devastating epidemics were measured in populations with higher levels of co-infection. Jointly, our results confirm the predictions made by theoretical and experimental studies for the potential of co-infection to alter disease dynamics across a large host-pathogen metapopulation. PMID:25569306

  16. Steinernema feltiae Intraspecific Variability: Infection Dynamics and Sex-Ratio

    PubMed Central

    Campos-Herrera, Raquel; Gutiérrez, Carmen

    2014-01-01

    Entomopathogenic nematodes (EPNs) from the Heterorhabditidae and Steinernematidae families are well-known biocontrol agents against numerous insect pests. The infective juveniles (IJs) are naturally occurring in the soil and their success in locating and penetrating the host will be affected by extrinsic/intrinsic factors that modulate their foraging behavior. Characterizing key traits in the infection dynamics of EPNs is critical for establishing differentiating species abilities to complete their life cycles and hence, their long-term persistence, in different habitats. We hypothesized that phenotypic variation in traits related to infection dynamics might occur in populations belonging to the same species. To assess these intraspecific differences, we evaluated the infection dynamics of 14 populations of Steinernema feltiae in two experiments measuring penetration and migration in sand column. Intraspecific variability was observed in the percentage larval mortality, time to kill the insect, penetration rate, and sex-ratio in both experiments (P < 0.01). Larval mortality and nematode penetration percentage were lower in migration experiments than in penetration ones in most of the cases. The sex-ratio was significantly biased toward female-development dominance (P < 0.05). When the populations were grouped by habitat of recovery (natural areas, crop edge, and agricultural groves), nematodes isolated in natural areas exhibited less larval mortality and penetration rates than those from some types of agricultural associated soils, suggesting a possible effect of the habitat on the phenotypic plasticity. This study reinforces the importance of considering intraspecific variability when general biological and ecological questions are addressed using EPNs. PMID:24644369

  17. Steinernema feltiae Intraspecific Variability: Infection Dynamics and Sex-Ratio.

    PubMed

    Campos-Herrera, Raquel; Gutiérrez, Carmen

    2014-03-01

    Entomopathogenic nematodes (EPNs) from the Heterorhabditidae and Steinernematidae families are well-known biocontrol agents against numerous insect pests. The infective juveniles (IJs) are naturally occurring in the soil and their success in locating and penetrating the host will be affected by extrinsic/intrinsic factors that modulate their foraging behavior. Characterizing key traits in the infection dynamics of EPNs is critical for establishing differentiating species abilities to complete their life cycles and hence, their long-term persistence, in different habitats. We hypothesized that phenotypic variation in traits related to infection dynamics might occur in populations belonging to the same species. To assess these intraspecific differences, we evaluated the infection dynamics of 14 populations of Steinernema feltiae in two experiments measuring penetration and migration in sand column. Intraspecific variability was observed in the percentage larval mortality, time to kill the insect, penetration rate, and sex-ratio in both experiments (P < 0.01). Larval mortality and nematode penetration percentage were lower in migration experiments than in penetration ones in most of the cases. The sex-ratio was significantly biased toward female-development dominance (P < 0.05). When the populations were grouped by habitat of recovery (natural areas, crop edge, and agricultural groves), nematodes isolated in natural areas exhibited less larval mortality and penetration rates than those from some types of agricultural associated soils, suggesting a possible effect of the habitat on the phenotypic plasticity. This study reinforces the importance of considering intraspecific variability when general biological and ecological questions are addressed using EPNs. PMID:24644369

  18. Steinernema feltiae Intraspecific Variability: Infection Dynamics and Sex-Ratio.

    PubMed

    Campos-Herrera, Raquel; Gutiérrez, Carmen

    2014-03-01

    Entomopathogenic nematodes (EPNs) from the Heterorhabditidae and Steinernematidae families are well-known biocontrol agents against numerous insect pests. The infective juveniles (IJs) are naturally occurring in the soil and their success in locating and penetrating the host will be affected by extrinsic/intrinsic factors that modulate their foraging behavior. Characterizing key traits in the infection dynamics of EPNs is critical for establishing differentiating species abilities to complete their life cycles and hence, their long-term persistence, in different habitats. We hypothesized that phenotypic variation in traits related to infection dynamics might occur in populations belonging to the same species. To assess these intraspecific differences, we evaluated the infection dynamics of 14 populations of Steinernema feltiae in two experiments measuring penetration and migration in sand column. Intraspecific variability was observed in the percentage larval mortality, time to kill the insect, penetration rate, and sex-ratio in both experiments (P < 0.01). Larval mortality and nematode penetration percentage were lower in migration experiments than in penetration ones in most of the cases. The sex-ratio was significantly biased toward female-development dominance (P < 0.05). When the populations were grouped by habitat of recovery (natural areas, crop edge, and agricultural groves), nematodes isolated in natural areas exhibited less larval mortality and penetration rates than those from some types of agricultural associated soils, suggesting a possible effect of the habitat on the phenotypic plasticity. This study reinforces the importance of considering intraspecific variability when general biological and ecological questions are addressed using EPNs.

  19. Osmolyte cooperation affects turgor dynamics in plants.

    PubMed

    Argiolas, Alfredo; Puleo, Gian Luigi; Sinibaldi, Edoardo; Mazzolai, Barbara

    2016-01-01

    Scientists have identified turgor-based actuation as a fundamental mechanism in plant movements. Plant cell turgor is generated by water influx due to the osmolyte concentration gradient through the cell wall and the plasma membrane behaving as an osmotic barrier. Previous studies have focused on turgor modulation with respect to potassium chloride (KCl) concentration changes, although KCl is not efficiently retained in the cell, and many other compounds, including L-glutamine (L-Gln) and D-glucose (D-Glc), are present in the cytosol. In fact, the contributions of other osmolytes to turgor dynamics remain to be elucidated. Here, we show the association of osmolytes and their consequent cooperative effects on the time-dependent turgor profile generated in a model cytosol consisting of KCl, D-Glc and L-Gln at experimentally measured plant motor/generic cell concentrations and at modified concentrations. We demonstrate the influence and association of the osmolytes using osmometry and NMR measurements. We also show, using a plant cell-inspired device we previously developed, that osmolyte complexes, rather than single osmolytes, permit to obtain higher turgor required by plant movements. We provide quantitative cues for deeper investigations of osmolyte transport for plant movement, and reveal the possibility of developing osmotic actuators exploiting a dynamically varying concentration of osmolytes. PMID:27445173

  20. Osmolyte cooperation affects turgor dynamics in plants

    PubMed Central

    Argiolas, Alfredo; Puleo, Gian Luigi; Sinibaldi, Edoardo; Mazzolai, Barbara

    2016-01-01

    Scientists have identified turgor-based actuation as a fundamental mechanism in plant movements. Plant cell turgor is generated by water influx due to the osmolyte concentration gradient through the cell wall and the plasma membrane behaving as an osmotic barrier. Previous studies have focused on turgor modulation with respect to potassium chloride (KCl) concentration changes, although KCl is not efficiently retained in the cell, and many other compounds, including L-glutamine (L-Gln) and D-glucose (D-Glc), are present in the cytosol. In fact, the contributions of other osmolytes to turgor dynamics remain to be elucidated. Here, we show the association of osmolytes and their consequent cooperative effects on the time-dependent turgor profile generated in a model cytosol consisting of KCl, D-Glc and L-Gln at experimentally measured plant motor/generic cell concentrations and at modified concentrations. We demonstrate the influence and association of the osmolytes using osmometry and NMR measurements. We also show, using a plant cell-inspired device we previously developed, that osmolyte complexes, rather than single osmolytes, permit to obtain higher turgor required by plant movements. We provide quantitative cues for deeper investigations of osmolyte transport for plant movement, and reveal the possibility of developing osmotic actuators exploiting a dynamically varying concentration of osmolytes. PMID:27445173

  1. Osmolyte cooperation affects turgor dynamics in plants

    NASA Astrophysics Data System (ADS)

    Argiolas, Alfredo; Puleo, Gian Luigi; Sinibaldi, Edoardo; Mazzolai, Barbara

    2016-07-01

    Scientists have identified turgor-based actuation as a fundamental mechanism in plant movements. Plant cell turgor is generated by water influx due to the osmolyte concentration gradient through the cell wall and the plasma membrane behaving as an osmotic barrier. Previous studies have focused on turgor modulation with respect to potassium chloride (KCl) concentration changes, although KCl is not efficiently retained in the cell, and many other compounds, including L-glutamine (L-Gln) and D-glucose (D-Glc), are present in the cytosol. In fact, the contributions of other osmolytes to turgor dynamics remain to be elucidated. Here, we show the association of osmolytes and their consequent cooperative effects on the time-dependent turgor profile generated in a model cytosol consisting of KCl, D-Glc and L-Gln at experimentally measured plant motor/generic cell concentrations and at modified concentrations. We demonstrate the influence and association of the osmolytes using osmometry and NMR measurements. We also show, using a plant cell-inspired device we previously developed, that osmolyte complexes, rather than single osmolytes, permit to obtain higher turgor required by plant movements. We provide quantitative cues for deeper investigations of osmolyte transport for plant movement, and reveal the possibility of developing osmotic actuators exploiting a dynamically varying concentration of osmolytes.

  2. Melissa officinalis oil affects infectivity of enveloped herpesviruses.

    PubMed

    Schnitzler, P; Schuhmacher, A; Astani, A; Reichling, Jürgen

    2008-09-01

    Extracts and essential oils of medicinal plants are increasingly of interest as novel drugs of antimicrobial and antiviral agents, since herpes simplex virus (HSV) might develop resistance to commonly used antiviral agents. Melissa officinalis essential oil was phytochemically examined by GC-MS analysis, its main constituents were identified as monoterpenaldehydes citral a, citral b and citronellal. The antiviral effect of lemon balm oil, the essential oil of Melissa officinalis, on herpes simplex virus was examined. The inhibitory activity against herpes simplex virus type 1 (HSV-1)and herpes simplex virus type 2 (HSV-2) was tested in vitro on monkey kidney cells using a plaque reduction assay. The 50% inhibitory concentration (IC50) of balm oil for herpes simplex virus plaque formation was determined at high dilutions of 0.0004% and 0.00008% for HSV-1 and HSV-2, respectively. At noncytotoxic concentrations of the oil,plaque formation was significantly reduced by 98.8% for HSV-1 and 97.2% for HSV-2, higher concentrations of lemon balm oil abolished viral infectivity nearly completely. In order to determine the mode of antiviral action of this essential oil, time-on-addition assays were performed. Both herpesviruses were significantly inhibited by pretreatment with balm oil prior to infection of cells. These results indicate that Melissa oil affected the virus before adsorption, but not after penetration into the host cell, thus lemon balm oil is capable of exerting a direct antiviral effect on herpesviruses. Considering the lipophilic nature of lemon balm essential oil, which enables it to penetrate the skin, and a high selectivity index, Melissa officinalis oil might be suitable for topical treatment of herpetic infections. PMID:18693101

  3. Melissa officinalis oil affects infectivity of enveloped herpesviruses.

    PubMed

    Schnitzler, P; Schuhmacher, A; Astani, A; Reichling, Jürgen

    2008-09-01

    Extracts and essential oils of medicinal plants are increasingly of interest as novel drugs of antimicrobial and antiviral agents, since herpes simplex virus (HSV) might develop resistance to commonly used antiviral agents. Melissa officinalis essential oil was phytochemically examined by GC-MS analysis, its main constituents were identified as monoterpenaldehydes citral a, citral b and citronellal. The antiviral effect of lemon balm oil, the essential oil of Melissa officinalis, on herpes simplex virus was examined. The inhibitory activity against herpes simplex virus type 1 (HSV-1)and herpes simplex virus type 2 (HSV-2) was tested in vitro on monkey kidney cells using a plaque reduction assay. The 50% inhibitory concentration (IC50) of balm oil for herpes simplex virus plaque formation was determined at high dilutions of 0.0004% and 0.00008% for HSV-1 and HSV-2, respectively. At noncytotoxic concentrations of the oil,plaque formation was significantly reduced by 98.8% for HSV-1 and 97.2% for HSV-2, higher concentrations of lemon balm oil abolished viral infectivity nearly completely. In order to determine the mode of antiviral action of this essential oil, time-on-addition assays were performed. Both herpesviruses were significantly inhibited by pretreatment with balm oil prior to infection of cells. These results indicate that Melissa oil affected the virus before adsorption, but not after penetration into the host cell, thus lemon balm oil is capable of exerting a direct antiviral effect on herpesviruses. Considering the lipophilic nature of lemon balm essential oil, which enables it to penetrate the skin, and a high selectivity index, Melissa officinalis oil might be suitable for topical treatment of herpetic infections.

  4. A mathematical approach to HIV infection dynamics

    NASA Astrophysics Data System (ADS)

    Ida, A.; Oharu, S.; Oharu, Y.

    2007-07-01

    In order to obtain a comprehensive form of mathematical models describing nonlinear phenomena such as HIV infection process and AIDS disease progression, it is efficient to introduce a general class of time-dependent evolution equations in such a way that the associated nonlinear operator is decomposed into the sum of a differential operator and a perturbation which is nonlinear in general and also satisfies no global continuity condition. An attempt is then made to combine the implicit approach (usually adapted for convective diffusion operators) and explicit approach (more suited to treat continuous-type operators representing various physiological interactions), resulting in a semi-implicit product formula. Decomposing the operators in this way and considering their individual properties, it is seen that approximation-solvability of the original model is verified under suitable conditions. Once appropriate terms are formulated to describe treatment by antiretroviral therapy, the time-dependence of the reaction terms appears, and such product formula is useful for generating approximate numerical solutions to the governing equations. With this knowledge, a continuous model for HIV disease progression is formulated and physiological interpretations are provided. The abstract theory is then applied to show existence of unique solutions to the continuous model describing the behavior of the HIV virus in the human body and its reaction to treatment by antiretroviral therapy. The product formula suggests appropriate discrete models describing the dynamics of host pathogen interactions with HIV1 and is applied to perform numerical simulations based on the model of the HIV infection process and disease progression. Finally, the results of our numerical simulations are visualized and it is observed that our results agree with medical and physiological aspects.

  5. Does influenza A virus infection affect movement behaviour during stopover in its wild reservoir host?

    PubMed

    Bengtsson, Daniel; Safi, Kamran; Avril, Alexis; Fiedler, Wolfgang; Wikelski, Martin; Gunnarsson, Gunnar; Elmberg, Johan; Tolf, Conny; Olsen, Björn; Waldenström, Jonas

    2016-02-01

    The last decade has seen a surge in research on avian influenza A viruses (IAVs), in part fuelled by the emergence, spread and potential zoonotic importance of highly pathogenic virus subtypes. The mallard (Anas platyrhynchos) is the most numerous and widespread dabbling duck in the world, and one of the most important natural hosts for studying IAV transmission dynamics. In order to predict the likelihood of IAV transmission between individual ducks and to other hosts, as well as between geographical regions, it is important to understand how IAV infection affects the host. In this study, we analysed the movements of 40 mallards equipped with GPS transmitters and three-dimensional accelerometers, of which 20 were naturally infected with low pathogenic avian influenza virus (LPAIV), at a major stopover site in the Northwest European flyway. Movements differed substantially between day and night, as well as between mallards returning to the capture site and those feeding in natural habitats. However, movement patterns did not differ between LPAIV infected and uninfected birds. Hence, LPAIV infection probably does not affect mallard movements during stopover, with high possibility of virus spread along the migration route as a consequence.

  6. Does influenza A virus infection affect movement behaviour during stopover in its wild reservoir host?

    PubMed Central

    Bengtsson, Daniel; Safi, Kamran; Avril, Alexis; Fiedler, Wolfgang; Wikelski, Martin; Gunnarsson, Gunnar; Elmberg, Johan; Tolf, Conny; Olsen, Björn; Waldenström, Jonas

    2016-01-01

    The last decade has seen a surge in research on avian influenza A viruses (IAVs), in part fuelled by the emergence, spread and potential zoonotic importance of highly pathogenic virus subtypes. The mallard (Anas platyrhynchos) is the most numerous and widespread dabbling duck in the world, and one of the most important natural hosts for studying IAV transmission dynamics. In order to predict the likelihood of IAV transmission between individual ducks and to other hosts, as well as between geographical regions, it is important to understand how IAV infection affects the host. In this study, we analysed the movements of 40 mallards equipped with GPS transmitters and three-dimensional accelerometers, of which 20 were naturally infected with low pathogenic avian influenza virus (LPAIV), at a major stopover site in the Northwest European flyway. Movements differed substantially between day and night, as well as between mallards returning to the capture site and those feeding in natural habitats. However, movement patterns did not differ between LPAIV infected and uninfected birds. Hence, LPAIV infection probably does not affect mallard movements during stopover, with high possibility of virus spread along the migration route as a consequence. PMID:26998334

  7. Studies of dynamical processes affecting global climate

    SciTech Connect

    Keller, C.; Cooper, D.; Eichinger, W.

    1998-12-31

    This is the final report of a three-year, Laboratory Directed Research and Development project at the Los Alamos National Laboratory (LANL). The main objective was, by a combined theoretical and observational approach, to develop improved models of dynamic processes in the oceans and atmosphere and to incorporate them into large climate codes, chiefly in four main areas: numerical physics, chemistry, water vapor, and ocean-atmosphere interactions. Main areas of investigation included studies of: cloud parameterizations for global climate codes, Lidar and the planetary boundary layer, chemistry, climate variability using coupled ocean-atmospheric models, and numerical physical methods. This project employed a unique approach that included participation of a number of University of California faculty, postdoctoral fellows and graduate students who collaborated with Los Alamos research staff on specific tasks, thus greatly enhancing the research output. Overall accomplishments during the sensing of the atmospheric planetary were: (1) first two- and three-dimensional remote sensing of the atmospheric planetary boundary layer using Lidars, (2) modeling of 20-year cycle in both pressure and sea surface temperatures in North Pacific, (3) modeling of low frequency internal variability, (4) addition of aerosols to stratosphere to simulate Pinatubo effect on ozone, (5) development of fast, comprehensive chemistry in the troposphere for urban pollution studies, (6) new prognostic cloud parameterization in global atmospheric code remedied problems with North Pacific atmospheric circulation and excessive equatorial precipitation, (7) development of a unique aerosol analysis technique, the aerosol time-of-flight mass spectrometer (ATOFMS), which allows real-time analysis of the size and chemical composition of individual aerosol particles, and (8) numerical physics applying Approximate Inertial Manifolds to ocean circulation. 14 refs., 6 figs.

  8. Does vaginal douching affect the type of candidal vulvovaginal infection?

    PubMed

    Shaaban, Omar M; Abbas, Ahmed M; Moharram, Ahmad M; Farhan, Mohammed M; Hassanen, Ibrahim H

    2015-11-01

    The normal vaginal microbiota is a dynamic system that continually fluctuates under the environmental changes and different physiological conditions. Yeast infections of the vagina are caused by one of the species of fungus called Candida (C.). The study aimed to evaluate the types of mycobiota in women with vulvovaginal candidiasis (VVC) who were performing vaginal douching (VD) or not. Furthermore, it studied the antifungal sensitivity toward different fungi isolated from the vagina. In a cross-sectional study conducted in Assiut University Hospital, Egypt, women with VVC were interviewed regarding relevant history including the habit of VD. Vaginal swabs were obtained and processed by direct microscope and by culture on CHROMagar Candida and other differential media. The types of Candida in women with the habit of VD were compared with those not having this habit. We found that VD habit was practiced by 67.4% of women with VVC, and Candida albicans was the commonest (78.3%) type observed. There was no significant difference in the percentage of non-albicans types between women performing VD (23.6%) and those not reporting this habit (18.9%). Harboring non-albicans types were significantly increased in regular performers of VD compared with those who had this procedure only after sexual intercourse or after the end of menstruation (36.8%,12.5%, and 16.7%, respectively) (P = .048). Thus, vaginal douching does not influence the type of Candida infection involved in VVC. Frequent performance of VD increases the likelihood of having non-albicans types and the resistance to the common antifungal agents. PMID:26129887

  9. Determinants and consequences of sexual networks as they affect the spread of sexually transmitted infections.

    PubMed

    Doherty, Irene A; Padian, Nancy S; Marlow, Cameron; Aral, Sevgi O

    2005-02-01

    Because pathogens spread only within the unique context of a sexual union between people when one person is infectious, the other is susceptible to new infection, and condoms are not used to prevent transmission, the epidemiological study of sexually transmitted infections (STIs) is particularly challenging. Social network analysis entails the study of ties among people and how the structure and quality of such ties affect individuals and overall group dynamics. Although ascertaining complete sexual networks is difficult, application of this approach has provided unique insights into the spread of STIs that traditional individual-based epidemiological methods do not capture. This article provides a brief background on the design and assessments of studies of social networks, to illustrate how these methods have been applied to understanding the distribution of STIs, to inform the development of interventions for STI control. PMID:15627230

  10. Mucin Dynamics in Intestinal Bacterial Infection

    PubMed Central

    Lindén, Sara K.; Florin, Timothy H. J.; McGuckin, Michael A.

    2008-01-01

    Background Bacterial gastroenteritis causes morbidity and mortality in humans worldwide. Murine Citrobacter rodentium infection is a model for gastroenteritis caused by the human pathogens enteropathogenic Escherichia coli and enterohaemorrhagic E. coli. Mucin glycoproteins are the main component of the first barrier that bacteria encounter in the intestinal tract. Methodology/Principal Findings Using Immunohistochemistry, we investigated intestinal expression of mucins (Alcian blue/PAS, Muc1, Muc2, Muc4, Muc5AC, Muc13 and Muc3/17) in healthy and C. rodentium infected mice. The majority of the C. rodentium infected mice developed systemic infection and colitis in the mid and distal colon by day 12. C. rodentium bound to the major secreted mucin, Muc2, in vitro, and high numbers of bacteria were found in secreted MUC2 in infected animals in vivo, indicating that mucins may limit bacterial access to the epithelial surface. In the small intestine, caecum and proximal colon, the mucin expression was similar in infected and non-infected animals. In the distal colonic epithelium, all secreted and cell surface mucins decreased with the exception of the Muc1 cell surface mucin which increased after infection (p<0.05). Similarly, during human infection Salmonella St Paul, Campylobacter jejuni and Clostridium difficile induced MUC1 in the colon. Conclusion Major changes in both the cell-surface and secreted mucins occur in response to intestinal infection. PMID:19088856

  11. Using experimental human influenza infections to validate a viral dynamic model and the implications for prediction.

    PubMed

    Chen, S C; You, S H; Liu, C Y; Chio, C P; Liao, C M

    2012-09-01

    The aim of this work was to use experimental infection data of human influenza to assess a simple viral dynamics model in epithelial cells and better understand the underlying complex factors governing the infection process. The developed study model expands on previous reports of a target cell-limited model with delayed virus production. Data from 10 published experimental infection studies of human influenza was used to validate the model. Our results elucidate, mechanistically, the associations between epithelial cells, human immune responses, and viral titres and were supported by the experimental infection data. We report that the maximum total number of free virions following infection is 10(3)-fold higher than the initial introduced titre. Our results indicated that the infection rates of unprotected epithelial cells probably play an important role in affecting viral dynamics. By simulating an advanced model of viral dynamics and applying it to experimental infection data of human influenza, we obtained important estimates of the infection rate. This work provides epidemiologically meaningful results, meriting further efforts to understand the causes and consequences of influenza A infection.

  12. Relations between affective music and speech: evidence from dynamics of affective piano performance and speech production.

    PubMed

    Liu, Xiaoluan; Xu, Yi

    2015-01-01

    This study compares affective piano performance with speech production from the perspective of dynamics: unlike previous research, this study uses finger force and articulatory effort as indexes reflecting the dynamics of affective piano performance and speech production respectively. Moreover, for the first time physical constraints such as piano fingerings and speech articulatory constraints are included due to their potential contribution to different patterns of dynamics. A piano performance experiment and speech production experiment were conducted in four emotions: anger, fear, happiness and sadness. The results show that in both piano performance and speech production, anger and happiness generally have high dynamics while sadness has the lowest dynamics. Fingerings interact with fear in the piano experiment and articulatory constraints interact with anger in the speech experiment, i.e., large physical constraints produce significantly higher dynamics than small physical constraints in piano performance under the condition of fear and in speech production under the condition of anger. Using production experiments, this study firstly supports previous perception studies on relations between affective music and speech. Moreover, this is the first study to show quantitative evidence for the importance of considering motor aspects such as dynamics in comparing music performance and speech production in which motor mechanisms play a crucial role. PMID:26217252

  13. Relations between affective music and speech: evidence from dynamics of affective piano performance and speech production

    PubMed Central

    Liu, Xiaoluan; Xu, Yi

    2015-01-01

    This study compares affective piano performance with speech production from the perspective of dynamics: unlike previous research, this study uses finger force and articulatory effort as indexes reflecting the dynamics of affective piano performance and speech production respectively. Moreover, for the first time physical constraints such as piano fingerings and speech articulatory constraints are included due to their potential contribution to different patterns of dynamics. A piano performance experiment and speech production experiment were conducted in four emotions: anger, fear, happiness and sadness. The results show that in both piano performance and speech production, anger and happiness generally have high dynamics while sadness has the lowest dynamics. Fingerings interact with fear in the piano experiment and articulatory constraints interact with anger in the speech experiment, i.e., large physical constraints produce significantly higher dynamics than small physical constraints in piano performance under the condition of fear and in speech production under the condition of anger. Using production experiments, this study firstly supports previous perception studies on relations between affective music and speech. Moreover, this is the first study to show quantitative evidence for the importance of considering motor aspects such as dynamics in comparing music performance and speech production in which motor mechanisms play a crucial role. PMID:26217252

  14. Relations between affective music and speech: evidence from dynamics of affective piano performance and speech production.

    PubMed

    Liu, Xiaoluan; Xu, Yi

    2015-01-01

    This study compares affective piano performance with speech production from the perspective of dynamics: unlike previous research, this study uses finger force and articulatory effort as indexes reflecting the dynamics of affective piano performance and speech production respectively. Moreover, for the first time physical constraints such as piano fingerings and speech articulatory constraints are included due to their potential contribution to different patterns of dynamics. A piano performance experiment and speech production experiment were conducted in four emotions: anger, fear, happiness and sadness. The results show that in both piano performance and speech production, anger and happiness generally have high dynamics while sadness has the lowest dynamics. Fingerings interact with fear in the piano experiment and articulatory constraints interact with anger in the speech experiment, i.e., large physical constraints produce significantly higher dynamics than small physical constraints in piano performance under the condition of fear and in speech production under the condition of anger. Using production experiments, this study firstly supports previous perception studies on relations between affective music and speech. Moreover, this is the first study to show quantitative evidence for the importance of considering motor aspects such as dynamics in comparing music performance and speech production in which motor mechanisms play a crucial role.

  15. The dynamics of hepatitis B virus infection.

    PubMed Central

    Payne, R J; Nowak, M A; Blumberg, B S

    1996-01-01

    We consider a cellular model of infection by the hepatitis B virus and describe how it may be used to account for two important features of the disease, namely (i) the wide variety of manifestations of infection and the age dependence thereof, and (ii) the typically long delay before the development of virus-induced liver cancer (primary hepatocellular carcinoma). The model is based on the assumption that the liver is comprised of both immature and mature hepatocytes, with these two subpopulations of cells responding contrastingly upon infection by the virus. PMID:8692852

  16. Dynamic Changes in Mucus Thickness and Ion Secretion during Citrobacter rodentium Infection and Clearance

    PubMed Central

    Rodriguez-Piñeiro, Ana M.; Alomran, Ala H. A.; Premaratne, Pushpa; Fernandez, Harvey R.; Banerjee, Debashish; Sjövall, Henrik; Hansson, Gunnar C.; Lindén, Sara K.

    2013-01-01

    Citrobacter rodentium is an attaching and effacing pathogen used as a murine model for enteropathogenic Escherichia coli. The mucus layers are a complex matrix of molecules, and mucus swelling, hydration and permeability are affected by many factors, including ion composition. Here, we used the C. rodentium model to investigate mucus dynamics during infection. By measuring the mucus layer thickness in tissue explants during infection, we demonstrated that the thickness changes dynamically during the course of infection and that its thickest stage coincides with the start of a decrease of bacterial density at day 14 after infection. Although quantitative PCR analysis demonstrated that mucin mRNA increases during early infection, the increased mucus layer thickness late in infection was not explained by increased mRNA levels. Proteomic analysis of mucus did not demonstrate the appearance of additional mucins, but revealed an increased number of proteins involved in defense responses. Ussing chamber-based electrical measurements demonstrated that ion secretion was dynamically altered during the infection phases. Furthermore, the bicarbonate ion channel Bestrophin-2 mRNA nominally increased, whereas the Cftr mRNA decreased during the late infection clearance phase. Microscopy of Muc2 immunostained tissues suggested that the inner striated mucus layer present in the healthy colon was scarce during the time point of most severe infection (10 days post infection), but then expanded, albeit with a less structured appearance, during the expulsion phase. Together with previously published literature, the data implies a model for clearance where a change in secretion allows reformation of the mucus layer, displacing the pathogen to the outer mucus layer, where it is then outcompeted by the returning commensal flora. In conclusion, mucus and ion secretion are dynamically altered during the C. rodentium infection cycle. PMID:24386378

  17. Positive Affect and the Complex Dynamics of Human Flourishing

    ERIC Educational Resources Information Center

    Fredrickson, Barbara L.; Losada, Marcial F.

    2005-01-01

    Extending B. L. Fredrickson's (1998) broaden-and-build theory of positive emotions and M. Losada's (1999) nonlinear dynamics model of team performance, the authors predict that a ratio of positive to negative affect at or above 2.9 will characterize individuals in flourishing mental health. Participants (N=188) completed an initial survey to…

  18. Quantification of viral infection dynamics in animal experiments

    PubMed Central

    Iwami, Shingo; Koizumi, Yoshiki; Ikeda, Hiroki; Kakizoe, Yusuke

    2013-01-01

    Analyzing the time-course of several viral infections using mathematical models based on experimental data can provide important quantitative insights regarding infection dynamics. Over the past decade, the importance and significance of mathematical modeling has been gaining recognition among virologists. In the near future, many animal models of human-specific infections and experimental data from high-throughput techniques will become available. This will provide us with the opportunity to develop new quantitative approaches, combining experimental and mathematical analyses. In this paper, we review the various quantitative analyses of viral infections and discuss their possible applications. PMID:24058361

  19. Previous infection with a mesogenic strain of Newcastle disease virus affects infection with highly pathogenic avian influenza viruses in chickens

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Avian influenza virus (AIV) and Newcastle disease virus (NDV) are two of the most important viruses affecting poultry worldwide, but little is known on the interactions between these two viruses when infecting birds. In a previous study we found that infection of chickens with a mesogenic strain of...

  20. Network Diversity and Affect Dynamics: The Role of Personality Traits

    PubMed Central

    Alshamsi, Aamena; Pianesi, Fabio; Lepri, Bruno; Pentland, Alex; Rahwan, Iyad

    2016-01-01

    People divide their time unequally among their social contacts due to time constraints and varying strength of relationships. It was found that high diversity of social communication, dividing time more evenly among social contacts, is correlated with economic well-being both at macro and micro levels. Besides economic well-being, it is not clear how the diversity of social communication is also associated with the two components of individuals’ subjective well-being, positive and negative affect. Specifically, positive affect and negative affect are two independent dimensions representing the experience (feeling) of emotions. In this paper, we investigate the relationship between the daily diversity of social communication and dynamic affect states that people experience in their daily lives. We collected two high-resolution datasets that capture affect scores via daily experience sampling surveys and social interaction through wearable sensing technologies: sociometric badges for face-to-face interaction and smart phones for mobile phone calls. We found that communication diversity correlates with desirable affect states–e.g. an increase in the positive affect state or a decrease in the negative affect state–for some personality types, but correlates with undesirable affect states for others. For example, diversity in phone calls is experienced as good by introverts, but bad by extroverts; diversity in face-to-face interaction is experienced as good by people who tend to be positive by nature (trait) but bad for people who tend to be not positive by nature. More broadly, the moderating effect of personality type on the relationship between diversity and affect was detected without any knowledge of the type of social tie or the content of communication. This provides further support for the power of unobtrusive sensing in understanding social dynamics, and in measuring the effect of potential interventions designed to improve well-being. PMID:27035904

  1. Network Diversity and Affect Dynamics: The Role of Personality Traits.

    PubMed

    Alshamsi, Aamena; Pianesi, Fabio; Lepri, Bruno; Pentland, Alex; Rahwan, Iyad

    2016-01-01

    People divide their time unequally among their social contacts due to time constraints and varying strength of relationships. It was found that high diversity of social communication, dividing time more evenly among social contacts, is correlated with economic well-being both at macro and micro levels. Besides economic well-being, it is not clear how the diversity of social communication is also associated with the two components of individuals' subjective well-being, positive and negative affect. Specifically, positive affect and negative affect are two independent dimensions representing the experience (feeling) of emotions. In this paper, we investigate the relationship between the daily diversity of social communication and dynamic affect states that people experience in their daily lives. We collected two high-resolution datasets that capture affect scores via daily experience sampling surveys and social interaction through wearable sensing technologies: sociometric badges for face-to-face interaction and smart phones for mobile phone calls. We found that communication diversity correlates with desirable affect states--e.g. an increase in the positive affect state or a decrease in the negative affect state--for some personality types, but correlates with undesirable affect states for others. For example, diversity in phone calls is experienced as good by introverts, but bad by extroverts; diversity in face-to-face interaction is experienced as good by people who tend to be positive by nature (trait) but bad for people who tend to be not positive by nature. More broadly, the moderating effect of personality type on the relationship between diversity and affect was detected without any knowledge of the type of social tie or the content of communication. This provides further support for the power of unobtrusive sensing in understanding social dynamics, and in measuring the effect of potential interventions designed to improve well-being.

  2. Network Diversity and Affect Dynamics: The Role of Personality Traits.

    PubMed

    Alshamsi, Aamena; Pianesi, Fabio; Lepri, Bruno; Pentland, Alex; Rahwan, Iyad

    2016-01-01

    People divide their time unequally among their social contacts due to time constraints and varying strength of relationships. It was found that high diversity of social communication, dividing time more evenly among social contacts, is correlated with economic well-being both at macro and micro levels. Besides economic well-being, it is not clear how the diversity of social communication is also associated with the two components of individuals' subjective well-being, positive and negative affect. Specifically, positive affect and negative affect are two independent dimensions representing the experience (feeling) of emotions. In this paper, we investigate the relationship between the daily diversity of social communication and dynamic affect states that people experience in their daily lives. We collected two high-resolution datasets that capture affect scores via daily experience sampling surveys and social interaction through wearable sensing technologies: sociometric badges for face-to-face interaction and smart phones for mobile phone calls. We found that communication diversity correlates with desirable affect states--e.g. an increase in the positive affect state or a decrease in the negative affect state--for some personality types, but correlates with undesirable affect states for others. For example, diversity in phone calls is experienced as good by introverts, but bad by extroverts; diversity in face-to-face interaction is experienced as good by people who tend to be positive by nature (trait) but bad for people who tend to be not positive by nature. More broadly, the moderating effect of personality type on the relationship between diversity and affect was detected without any knowledge of the type of social tie or the content of communication. This provides further support for the power of unobtrusive sensing in understanding social dynamics, and in measuring the effect of potential interventions designed to improve well-being. PMID:27035904

  3. Daily Interpersonal and Affective Dynamics in Personality Disorder

    PubMed Central

    Wright, Aidan G.C.; Hopwood, Christopher J.; Simms, Leonard J.

    2015-01-01

    In this naturalistic study we adopt the lens of interpersonal theory to examine between-and within-person differences in dynamic processes of daily affect and interpersonal behaviors among individuals (N = 101) previously diagnosed with personality disorders who completed daily diaries over the course of 100 days. Dispositional ratings of interpersonal problems and measures of daily stress were used as predictors of daily shifts in interpersonal behavior and affect in multilevel models. Results indicate that ~40%–50% of the variance in interpersonal behavior and affect is due to daily fluctuations, which are modestly related to dispositional measures of interpersonal problems but strongly related to daily stress. The findings support conceptions of personality disorders as a dynamic form of psychopathology involving the individuals interacting with and regulating in response to the contextual features of their environment. PMID:26200849

  4. Socioeconomic and environmental factors affecting malaria infection in Fayoum Governorate, Egypt.

    PubMed

    Dahesh, Salwa M; Bassiouny, Hassan K; El-Masry, Sana A

    2009-08-01

    Malaria as a disease has been identified in Egypt since ancient times. Remnant residual foci are still localized in two districts; Sinnuris and Faiyoum, Faiyoum Governorate. The work focused on socioeconomic and environmental factors affecting malaria infection. The results showed that malaria infection increase with the decrease of socioeconomic level of families, educational level of examined individuals and among unemployed or students. The infection increase among those lived in muddy or bad constructed house near the breeding places. The infection decreased significantly among who owned animal sheds and had large number of animals. The indoors use of 5% mala-thion did not affect the malaria infection.

  5. Physical, chemical and kinetic factors affecting prion infectivity

    PubMed Central

    Properzi, Francesca; Badhan, Anjna; Klier, Steffi; Schmidt, Christian; Klöhn, Peter C.; Wadsworth, Jonathan D. F.; Clarke, Anthony R.; Jackson, Graham S.; Collinge, John

    2016-01-01

    ABSTRACT The mouse-adapted scrapie prion strain RML is one of the most widely used in prion research. The introduction of a cell culture-based assay of RML prions, the scrapie cell assay (SCA) allows more rapid and precise prion titration. A semi-automated version of this assay (ASCA) was applied to explore a range of conditions that might influence the infectivity and properties of RML prions. These include resistance to freeze-thaw procedures; stability to endogenous proteases in brain homogenate despite prolonged exposure to varying temperatures; distribution of infective material between pellet and supernatant after centrifugation, the effect of reducing agents and the influence of detergent additives on the efficiency of infection. Apparent infectivity is increased significantly by interaction with cationic detergents. Importantly, we have also elucidated the relationship between the duration of exposure of cells to RML prions and the transmission of infection. We established that the infection process following contact of cells with RML prions is rapid and followed an exponential time course, implying a single rate-limiting process. PMID:27282252

  6. Factors Affecting Population Dynamics of Maternally Transmitted Endosymbionts in Bemisia tabaci

    PubMed Central

    Pan, Huipeng; Li, Xianchun; Ge, Daqing; Wang, Shaoli; Wu, Qingjun; Xie, Wen; Jiao, Xiaoguo; Chu, Dong; Liu, Baiming; Xu, Baoyun; Zhang, Youjun

    2012-01-01

    While every individual of Bemisia tabaci (Hemiptera: Aleyrodidae) harbors the primary symbiont (P-symbiont) Portiera, the infection frequencies of the six secondary symbionts (S-symbionts) including Hamiltonella, Arsenophonus, Cardinium, Wolbachia, Rickettsia and Fritschea vary greatly among different populations. To characterize the factors influencing the infection dynamics of the six S-symbionts in B. tabaci, gene-specific PCR were conducted to screen for the presence of the P-symbiont Portiera and the six S-symbionts in 61 (17 B and 44 Q biotypes) field populations collected from different plant species and locations in China. All individuals of the 61 populations hosted the P-symbiont Portiera, but none of them harbored Arsenophonus and Fritschea. The presence and infection rates of Hamiltonella, Cardinium, Rickettsia, Wolbachia and their co-infections Rickettsia + Hamiltonella (RH), Rickettsia + Cardinium (RC), Hamiltonella + Cardinium (HC) and Rickettsia + Hamiltonella + Cardinium (RHC) varied significantly among the 61 field populations; and the observed variations can be explained by biotypes, sexes, host plants and geographical locations of these field populations. Taken together, at least three factors including biotype, host plant and geographical location affect the infection dynamics of S-symbionts in B. tabaci. PMID:22383972

  7. Factors affecting population dynamics of maternally transmitted endosymbionts in Bemisia tabaci.

    PubMed

    Pan, Huipeng; Li, Xianchun; Ge, Daqing; Wang, Shaoli; Wu, Qingjun; Xie, Wen; Jiao, Xiaoguo; Chu, Dong; Liu, Baiming; Xu, Baoyun; Zhang, Youjun

    2012-01-01

    While every individual of Bemisia tabaci (Hemiptera: Aleyrodidae) harbors the primary symbiont (P-symbiont) Portiera, the infection frequencies of the six secondary symbionts (S-symbionts) including Hamiltonella, Arsenophonus, Cardinium, Wolbachia, Rickettsia and Fritschea vary greatly among different populations. To characterize the factors influencing the infection dynamics of the six S-symbionts in B. tabaci, gene-specific PCR were conducted to screen for the presence of the P-symbiont Portiera and the six S-symbionts in 61 (17 B and 44 Q biotypes) field populations collected from different plant species and locations in China. All individuals of the 61 populations hosted the P-symbiont Portiera, but none of them harbored Arsenophonus and Fritschea. The presence and infection rates of Hamiltonella, Cardinium, Rickettsia, Wolbachia and their co-infections Rickettsia + Hamiltonella (RH), Rickettsia + Cardinium (RC), Hamiltonella + Cardinium (HC) and Rickettsia + Hamiltonella + Cardinium (RHC) varied significantly among the 61 field populations; and the observed variations can be explained by biotypes, sexes, host plants and geographical locations of these field populations. Taken together, at least three factors including biotype, host plant and geographical location affect the infection dynamics of S-symbionts in B. tabaci.

  8. Infection dynamics on scale-free networks

    NASA Astrophysics Data System (ADS)

    May, Robert M.; Lloyd, Alun L.

    2001-12-01

    We discuss properties of infection processes on scale-free networks, relating them to the node-connectivity distribution that characterizes the network. Considering the epidemiologically important case of a disease that confers permanent immunity upon recovery, we derive analytic expressions for the final size of an epidemic in an infinite closed population and for the dependence of infection probability on an individual's degree of connectivity within the population. As in an earlier study [R. Pastor-Satorras and A. Vesipignani, Phys. Rev. Lett. 86, 3200 (2001); Phys. Rev. E. 63, 006117 (2001)] for an infection that did not confer immunity upon recovery, the epidemic process-in contrast with many traditional epidemiological models-does not exhibit threshold behavior, and we demonstrate that this is a consequence of the extreme heterogeneity in the connectivity distribution of a scale-free network. Finally, we discuss effects that arise from finite population sizes, showing that networks of finite size do exhibit threshold effects: infections cannot spread for arbitrarily low transmission probabilities.

  9. Respiratory Syncytial Virus Infections in Infants Affected by Primary Immunodeficiency

    PubMed Central

    Capretti, Maria Grazia; Lazzarotto, Tiziana; Faldella, Giacomo

    2014-01-01

    Primary immunodeficiencies are rare inherited disorders that may lead to frequent and often severe acute respiratory infections. Respiratory syncytial virus (RSV) is one of the most frequent pathogens during early infancy and the infection is more severe in immunocompromised infants than in healthy infants, as a result of impaired T- and B-cell immune response unable to efficaciously neutralize viral replication, with subsequent increased viral shedding and potentially lethal lower respiratory tract infection. Several authors have reported a severe clinical course after RSV infections in infants and children with primary and acquired immunodeficiencies. Environmental prophylaxis is essential in order to reduce the infection during the epidemic season in hospitalized immunocompromised infants. Prophylaxis with palivizumab, a humanized monoclonal antibody against the RSV F protein, is currently recommended in high-risk infants born prematurely, with chronic lung disease or congenital heart disease. Currently however the prophylaxis is not routinely recommended in infants with primary immunodeficiency, although some authors propose the extension of prophylaxis to this high risk population. PMID:25089282

  10. Inferring Viral Dynamics in Chronically HCV Infected Patients from the Spatial Distribution of Infected Hepatocytes

    DOE PAGES

    Graw, Frederik; Balagopal, Ashwin; Kandathil, Abraham J.; Ray, Stuart C.; Thomas, David L.; Ribeiro, Ruy M.; Perelson, Alan S.; Yates, Andrew J.

    2014-11-13

    Chronic liver infection by hepatitis C virus (HCV) is a major public health concern. Despite partly successful treatment options, several aspects of intrahepatic HCV infection dynamics are still poorly understood, including the preferred mode of viral propagation, as well as the proportion of infected hepatocytes. Answers to these questions have important implications for the development of therapeutic interventions. In this study, we present methods to analyze the spatial distribution of infected hepatocytes obtained by single cell laser capture microdissection from liver biopsy samples of patients chronically infected with HCV. By characterizing the internal structure of clusters of infected cells, wemore » are able to evaluate hypotheses about intrahepatic infection dynamics. We found that individual clusters on biopsy samples range in size from 4-50 infected cells. In addition, the HCV RNA content in a cluster declines from the cell that presumably founded the cluster to cells at the maximal cluster extension. These observations support the idea that HCV infection in the liver is seeded randomly (e.g. from the blood) and then spreads locally. Assuming that the amount of intracellular HCV RNA is a proxy for how long a cell has been infected, we estimate based on models of intracellular HCV RNA replication and accumulation that cells in clusters have been infected on average for less than a week. Further, we do not find a relationship between the cluster size and the estimated cluster expansion time. Lastly, our method represents a novel approach to make inferences about infection dynamics in solid tissues from static spatial data.« less

  11. Inferring Viral Dynamics in Chronically HCV Infected Patients from the Spatial Distribution of Infected Hepatocytes

    SciTech Connect

    Graw, Frederik; Balagopal, Ashwin; Kandathil, Abraham J.; Ray, Stuart C.; Thomas, David L.; Ribeiro, Ruy M.; Perelson, Alan S.; Yates, Andrew J.

    2014-11-13

    Chronic liver infection by hepatitis C virus (HCV) is a major public health concern. Despite partly successful treatment options, several aspects of intrahepatic HCV infection dynamics are still poorly understood, including the preferred mode of viral propagation, as well as the proportion of infected hepatocytes. Answers to these questions have important implications for the development of therapeutic interventions. In this study, we present methods to analyze the spatial distribution of infected hepatocytes obtained by single cell laser capture microdissection from liver biopsy samples of patients chronically infected with HCV. By characterizing the internal structure of clusters of infected cells, we are able to evaluate hypotheses about intrahepatic infection dynamics. We found that individual clusters on biopsy samples range in size from 4-50 infected cells. In addition, the HCV RNA content in a cluster declines from the cell that presumably founded the cluster to cells at the maximal cluster extension. These observations support the idea that HCV infection in the liver is seeded randomly (e.g. from the blood) and then spreads locally. Assuming that the amount of intracellular HCV RNA is a proxy for how long a cell has been infected, we estimate based on models of intracellular HCV RNA replication and accumulation that cells in clusters have been infected on average for less than a week. Further, we do not find a relationship between the cluster size and the estimated cluster expansion time. Lastly, our method represents a novel approach to make inferences about infection dynamics in solid tissues from static spatial data.

  12. Density dynamics of diverse Spiroplasma strains naturally infecting different species of Drosophila

    PubMed Central

    Haselkorn, Tamara S; Watts, Thomas D; Markow, Therese A

    2013-01-01

    Facultative heritable bacterial endosymbionts can have dramatic effects on their hosts, ranging from mutualistic to parasitic. Within-host bacterial endosymbiont density plays a critical role in maintenance of a symbiotic relationship, as it can affect levels of vertical transmission and expression of phenotypic effects, both of which influence the infection prevalence in host populations. Species of genus Drosophila are infected with Spiroplasma, whose characterized phenotypic effects range from that of a male-killing reproductive parasite to beneficial defensive endosymbiont. For many strains of Spiroplasma infecting at least 17 species of Drosophila, however, the phenotypic effects are obscure. The infection prevalence of these Spiroplasma vary within and among Drosophila species, and little is known about the within-host density dynamics of these diverse strains. To characterize the patterns of Spiroplasma density variation among Drosophila we used quantitative PCR to assess bacterial titer at various life stages of three species of Drosophila naturally-infected with two different types of Spiroplasma. For naturally infected Drosophila species we found that non-male-killing infections had consistently lower densities than the male-killing infection. The patterns of Spiroplasma titer change during aging varied among Drosophila species infected with different Spiroplasma strains. Bacterial density varied within and among populations of Drosophila, with individuals from the population with the highest prevalence of infection having the highest density. This density variation underscores the complex interaction of Spiroplasma strain and host genetic background in determining endosymbiont density. PMID:23846301

  13. Age-structured dynamic, stochastic and mechanistic simulation model of Salmonella Dublin infection within dairy herds.

    PubMed

    Nielsen, Liza Rosenbaum; Kudahl, Anne Braad; Østergaard, Søren

    2012-06-01

    In the demand for a decision support tool to guide farmers wanting to control Salmonella Dublin (S. Dublin) in Danish dairy herds, we developed an age-structured stochastic, mechanistic and dynamic simulation model of S. Dublin in dairy herds, which incorporated six age groups (neonatal, preweaned calves, weaned calves, growing heifers, breeding heifers and cows) and five infection states (susceptible, acutely infected, carrier, super shedder and resistant). The model simulated population and infection dynamics over a period of 10 years in weekly time steps as: 1) population sizes of each of the six age-groups; 2) S. Dublin incidence and number of animals in each infection state; and 3) S. Dublin related morbidity and mortality in the acutely infected animals. The effects of introducing one infectious heifer on the risk of spread of S. Dublin within the herd and on the duration of infection were estimated through 1000 simulation iterations for 48 scenarios. The scenarios covered all combinations of three herd sizes (70, 200 and 400 cows), four hygiene levels indicating infectious contact parameters, and four herd susceptibility levels indicating different susceptibility parameters for the individual animals in each of the six age groups in the herd. The hygiene level was highly influential on the probability that the infection spread within the herd, duration of infection and epidemic size. The herd susceptibility level was also influential, but not likely to provide sufficient prevention and control of infection on its own. Herd size did not affect the probability of infection spread upon exposure, but the larger the herd the more important were management and housing practices that improve hygiene and reduce susceptibility to shorten durations of infection in the herd and to increase the probability of extinction. In general, disease and mortality patterns followed epidemic waves in the herds. However, an interesting pattern was seen for acute infections and

  14. Dynamics of immunoglobulin sequence diversity in HIV-1 infected individuals

    PubMed Central

    Hoehn, Kenneth B.; Gall, Astrid; Bashford-Rogers, Rachael; Fidler, S. J.; Kaye, S.; Weber, J. N.; McClure, M. O.; Kellam, Paul; Pybus, Oliver G.

    2015-01-01

    Advances in immunoglobulin (Ig) sequencing technology are leading to new perspectives on immune system dynamics. Much research in this nascent field has focused on resolving immune responses to viral infection. However, the dynamics of B-cell diversity in early HIV infection, and in response to anti-retroviral therapy, are still poorly understood. Here, we investigate these dynamics through bulk Ig sequencing of samples collected over 2 years from a group of eight HIV-1 infected patients, five of whom received anti-retroviral therapy during the first half of the study period. We applied previously published methods for visualizing and quantifying B-cell sequence diversity, including the Gini index, and compared their efficacy to alternative measures. While we found significantly greater clonal structure in HIV-infected patients versus healthy controls, within HIV patients, we observed no significant relationships between statistics of B-cell clonal expansion and clinical variables such as viral load and CD4+ count. Although there are many potential explanations for this, we suggest that important factors include poor sampling resolution and complex B-cell dynamics that are difficult to summarize using simple summary statistics. Importantly, we find a significant association between observed Gini indices and sequencing read depth, and we conclude that more robust analytical methods and a closer integration of experimental and theoretical work is needed to further our understanding of B-cell repertoire diversity during viral infection. PMID:26194755

  15. The Dynamics of Ascaris lumbricoides Infections.

    PubMed

    Fowler, A C; Déirdre Hollingsworth, T

    2016-04-01

    The Anderson-May model of human parasite infections and specifically that for the intestinal worm Ascaris lumbricoides is reconsidered, with a view to deriving the observed characteristic negative binomial distribution which is frequently found in human communities. The means to obtaining this result lies in reformulating the continuous Anderson-May model as a stochastic process involving two essential populations, the density of mature worms in the gut, and the density of mature eggs in the environment. The resulting partial differential equation for the generating function of the joint probability distribution of eggs and worms can be partially solved in the appropriate limit where the worm lifetime is much greater than that of the mature eggs in the environment. Allowing for a mean field nonlinearity, and for egg immigration from neighbouring communities, a negative binomial worm distribution can be predicted, whose parameters are determined by those in the continuous Anderson-May model; this result assumes no variability in predisposition to the infection. PMID:27066982

  16. The Dynamics of Ascaris lumbricoides Infections.

    PubMed

    Fowler, A C; Déirdre Hollingsworth, T

    2016-04-01

    The Anderson-May model of human parasite infections and specifically that for the intestinal worm Ascaris lumbricoides is reconsidered, with a view to deriving the observed characteristic negative binomial distribution which is frequently found in human communities. The means to obtaining this result lies in reformulating the continuous Anderson-May model as a stochastic process involving two essential populations, the density of mature worms in the gut, and the density of mature eggs in the environment. The resulting partial differential equation for the generating function of the joint probability distribution of eggs and worms can be partially solved in the appropriate limit where the worm lifetime is much greater than that of the mature eggs in the environment. Allowing for a mean field nonlinearity, and for egg immigration from neighbouring communities, a negative binomial worm distribution can be predicted, whose parameters are determined by those in the continuous Anderson-May model; this result assumes no variability in predisposition to the infection.

  17. Positive Affect and the Complex Dynamics of Human Flourishing

    PubMed Central

    Fredrickson, Barbara L.; Losada, Marcial F.

    2011-01-01

    Extending B. L. Fredrickson’s (1998) broaden-and-build theory of positive emotions and M. Losada’s (1999) nonlinear dynamics model of team performance, the authors predict that a ratio of positive to negative affect at or above 2.9 will characterize individuals in flourishing mental health. Participants (N = 188) completed an initial survey to identify flourishing mental health and then provided daily reports of experienced positive and negative emotions over 28 days. Results showed that the mean ratio of positive to negative affect was above 2.9 for individuals classified as flourishing and below that threshold for those not flourishing. Together with other evidence, these findings suggest that a set of general mathematical principles may describe the relations between positive affect and human flourishing. PMID:16221001

  18. Positive affect and the complex dynamics of human flourishing.

    PubMed

    Fredrickson, Barbara L; Losada, Marcial F

    2005-10-01

    Extending B. L. Fredrickson's (1998) broaden-and-build theory of positive emotions and M. Losada's (1999) nonlinear dynamics model of team performance, the authors predict that a ratio of positive to negative affect at or above 2.9 will characterize individuals in flourishing mental health. Participants (N=188) completed an initial survey to identify flourishing mental health and then provided daily reports of experienced positive and negative emotions over 28 days. Results showed that the mean ratio of positive to negative affect was above 2.9 for individuals classified as flourishing and below that threshold for those not flourishing. Together with other evidence, these findings suggest that a set of general mathematical principles may describe the relations between positive affect and human flourishing. PMID:16221001

  19. Ionosphere-Earth current density affecting clouds and atmospheric dynamics

    NASA Astrophysics Data System (ADS)

    Tinsley, Brian; Burns, Gary

    Ionosphere-Earth current density affecting clouds and atmospheric dynamics Correlations of atmospheric dynamics, cloud cover, and precipitation with changes in external and internal inputs that affect the downward ionosphere-earth current density, Jz, through the atmosphere have been reported on day-to-day, decadal, century and longer timescales. Such inputs are changes in the cosmic ray flux; in the interplanetary electric field; in solar energetic particles; in relativistic electron precipitation; and in the upward current output of global thunderstorm activity. The interplanetary electric field and relativistic electron and thunderstorm inputs affect Jz while not changing the tropospheric ionization rate, thus ruling out ion-mediated nucleation as the mechanism affecting the cloud processes. Modeling suggests that charge modulation of aerosol scavenging (CMAS) in clouds affects cloud microphysics and can account for the correlations. The CMAS effects are different for cold clouds as compared to warm clouds, and vary with the size of the condensation nuclei and ice-forming nuclei. CMAS effects on cold and warm cloud lifetimes can account for observed changes in cloud cover on day-to-day and decadal time scales. CMAS effects on precipitation from cold clouds can account for increases in winter storm vorticity in cyclogenesis regions. Increases in cyclonic vorticity in these regions generates anticyclonic blocking a half Rossby wavelength downstream. These affect storm tracks and the advection of cold Arctic air in winter onto the continents. Observations, theory and modeling of cloud microphysics supporting these chains of processes will be reviewed, but the needed modeling of resolved clouds and their insertion into GCMs is complex and demanding, and has yet to be undertaken.

  20. Modeling malaria and typhoid fever co-infection dynamics.

    PubMed

    Mutua, Jones M; Wang, Feng-Bin; Vaidya, Naveen K

    2015-06-01

    Malaria and typhoid are among the most endemic diseases, and thus, of major public health concerns in tropical developing countries. In addition to true co-infection of malaria and typhoid, false diagnoses due to similar signs and symptoms and false positive results in testing methods, leading to improper controls, are the major challenges on managing these diseases. In this study, we develop novel mathematical models describing the co-infection dynamics of malaria and typhoid. Through mathematical analyses of our models, we identify distinct features of typhoid and malaria infection dynamics as well as relationships associated to their co-infection. The global dynamics of typhoid can be determined by a single threshold (the typhoid basic reproduction number, R0(T)) while two thresholds (the malaria basic reproduction number, R0(M), and the extinction index, R0(MM)) are needed to determine the global dynamics of malaria. We demonstrate that by using efficient simultaneous prevention programs, the co-infection basic reproduction number, R0, can be brought down to below one, thereby eradicating the diseases. Using our model, we present illustrative numerical results with a case study in the Eastern Province of Kenya to quantify the possible false diagnosis resulting from this co-infection. In Kenya, despite having higher prevalence of typhoid, malaria is more problematic in terms of new infections and disease deaths. We find that false diagnosis-with higher possible cases for typhoid than malaria-cause significant devastating impacts on Kenyan societies. Our results demonstrate that both diseases need to be simultaneously managed for successful control of co-epidemics. PMID:25865934

  1. Infection rates and comparative population dynamics of Peregrinus maidis (Hemiptera: Delphacidae) on corn plants with and without symptoms of maize mosaic virus (Rhabdoviridae: Nucleorhabdovirus) infection.

    PubMed

    Higashi, C H V; Bressan, A

    2013-10-01

    We examined the population dynamics of the corn planthopper Peregrinus maidis (Ashmead) (Hemiptera: Delphacidae) throughout a cycle of corn (Zea mays L.) production on plants with or without symptoms of maize mosaic virus (MMV) (Rhabdoviridae: Nucleorhabdovirus) infection. Our results indicate that the timing of MMV plant infection greatly influenced the planthopper's host plant colonization patterns. Corn plants that expressed symptoms of MMV infection early in the crop cycle (28 d after planting) harbored, on average, 40 and 48% fewer planthoppers than plants that expressed symptoms of MMV infection later in the crop cycle (49 d after planting) and asymptomatic plants, respectively. We also observed a change in the number of brachypterous (short-wing type) and macropterous (long-wing type) winged forms produced; plants expressing early symptoms of MMV infection harbored, on average, 41 and 47% more of the brachypterous form than plants with late infections of MMV and plants with no symptoms of MMV, respectively. Furthermore, we determined the rates of MMV-infected planthoppers relative to their wing morphology (macropterous or brachypterous) and gender. MMV infection was 5 and 12% higher in females than in males in field and greenhouse experiments, respectively; however, these differences were not significantly different. This research provides evidence that MMV similarly infects P. maidis planthoppers regardless of the gender and wing morphotype. These results also suggest that the timing of symptom development greatly affects the population dynamics of the planthopper vector, and likely has important consequences for the dynamics of the disease in the field.

  2. Predicting when climate-driven phenotypic change affects population dynamics.

    PubMed

    McLean, Nina; Lawson, Callum R; Leech, Dave I; van de Pol, Martijn

    2016-06-01

    Species' responses to climate change are variable and diverse, yet our understanding of how different responses (e.g. physiological, behavioural, demographic) relate and how they affect the parameters most relevant for conservation (e.g. population persistence) is lacking. Despite this, studies that observe changes in one type of response typically assume that effects on population dynamics will occur, perhaps fallaciously. We use a hierarchical framework to explain and test when impacts of climate on traits (e.g. phenology) affect demographic rates (e.g. reproduction) and in turn population dynamics. Using this conceptual framework, we distinguish four mechanisms that can prevent lower-level responses from impacting population dynamics. Testable hypotheses were identified from the literature that suggest life-history and ecological characteristics which could predict when these mechanisms are likely to be important. A quantitative example on birds illustrates how, even with limited data and without fully-parameterized population models, new insights can be gained; differences among species in the impacts of climate-driven phenological changes on population growth were not explained by the number of broods or density dependence. Our approach helps to predict the types of species in which climate sensitivities of phenotypic traits have strong demographic and population consequences, which is crucial for conservation prioritization of data-deficient species.

  3. Predicting when climate-driven phenotypic change affects population dynamics.

    PubMed

    McLean, Nina; Lawson, Callum R; Leech, Dave I; van de Pol, Martijn

    2016-06-01

    Species' responses to climate change are variable and diverse, yet our understanding of how different responses (e.g. physiological, behavioural, demographic) relate and how they affect the parameters most relevant for conservation (e.g. population persistence) is lacking. Despite this, studies that observe changes in one type of response typically assume that effects on population dynamics will occur, perhaps fallaciously. We use a hierarchical framework to explain and test when impacts of climate on traits (e.g. phenology) affect demographic rates (e.g. reproduction) and in turn population dynamics. Using this conceptual framework, we distinguish four mechanisms that can prevent lower-level responses from impacting population dynamics. Testable hypotheses were identified from the literature that suggest life-history and ecological characteristics which could predict when these mechanisms are likely to be important. A quantitative example on birds illustrates how, even with limited data and without fully-parameterized population models, new insights can be gained; differences among species in the impacts of climate-driven phenological changes on population growth were not explained by the number of broods or density dependence. Our approach helps to predict the types of species in which climate sensitivities of phenotypic traits have strong demographic and population consequences, which is crucial for conservation prioritization of data-deficient species. PMID:27062059

  4. A Sharing Experience: Development of a Group for Families Affected by HIV Infection.

    ERIC Educational Resources Information Center

    Melvin, Diane; Appleby, Sue

    1995-01-01

    Describes the establishment and development of a support group for the parents of children infected and/or affected by HIV infection. The group is hospital-based, meeting monthly since April 1992, facilitated by professionals but with a self-help and peer support emphasis. Explains the planning, setting, and running of the group. Identifies…

  5. Priming semantic concepts affects the dynamics of aesthetic appreciation.

    PubMed

    Faerber, Stella J; Leder, Helmut; Gerger, Gernot; Carbon, Claus-Christian

    2010-10-01

    Aesthetic appreciation (AA) plays an important role for purchase decisions, for the appreciation of art and even for the selection of potential mates. It is known that AA is highly reliable in single assessments, but over longer periods of time dynamic changes of AA may occur. We measured AA as a construct derived from the literature through attractiveness, arousal, interestingness, valence, boredom and innovativeness. By means of the semantic network theory we investigated how the priming of AA-relevant semantic concepts impacts the dynamics of AA of unfamiliar product designs (car interiors) that are known to be susceptible to triggering such effects. When participants were primed for innovativeness, strong dynamics were observed, especially when the priming involved additional AA-relevant dimensions. This underlines the relevance of priming of specific semantic networks not only for the cognitive processing of visual material in terms of selective perception or specific representation, but also for the affective-cognitive processing in terms of the dynamics of aesthetic processing.

  6. Dynamics of phytoplankton communities in eutrophying tropical shrimp ponds affected by vibriosis.

    PubMed

    Lemonnier, Hugues; Lantoine, François; Courties, Claude; Guillebault, Delphine; Nézan, Elizabeth; Chomérat, Nicolas; Escoubeyrou, Karine; Galinié, Christian; Blockmans, Bernard; Laugier, Thierry

    2016-09-15

    Tropical shrimp aquaculture systems in New Caledonia regularly face major crises resulting from outbreaks of Vibrio infections. Ponds are highly dynamic and challenging environments and display a wide range of trophic conditions. In farms affected by vibriosis, phytoplankton biomass and composition are highly variable. These conditions may promote the development of harmful algae increasing shrimp susceptibility to bacterial infections. Phytoplankton compartment before and during mortality outbreaks was monitored at a shrimp farm that has been regularly and highly impacted by these diseases. Combining information from flow cytometry, microscopy, pigment and phylogenetic analysis, the presence of Picocyanobacteria, Prasinophyceae and Diatomophyceae were detected as dominant phytoplankton groups and Cryptophyceae, Prymnesiophyceae and Dinophyceae as minor components. At the onset of the first shrimp mortalities, Bacillariophyceae increased while Cyanobacteria, Prymnesiophyceae and Dinophyceae decreased in the water column, followed by proliferation of Prasinophyceae. Several taxa were identified as potential harmful algae (Cyanobacteria, dinoflagellates and Phaeocystis).

  7. A hyperparasite affects the population dynamics of a wild plant pathogen

    PubMed Central

    Tollenaere, C; Pernechele, B; Mäkinen, H S; Parratt, S R; Németh, M Z; Kovács, G M; Kiss, L; Tack, A J M; Laine, A-L

    2014-01-01

    Assessing the impact of natural enemies of plant and animal pathogens on their host's population dynamics is needed to determine the role of hyperparasites in affecting disease dynamics, and their potential for use in efficient control strategies of pathogens. Here, we focus on the long-term study describing metapopulation dynamics of an obligate pathogen, the powdery mildew (Podosphaera plantaginis) naturally infecting its wild host plant (Plantago lanceolata) in the fragmented landscape of the Åland archipelago (southwest Finland). Regionally, the pathogen persists through a balance of extinctions and colonizations, yet factors affecting extinction rates remain poorly understood. Mycoparasites of the genus Ampelomyces appear as good candidates for testing the role of a hyperparasite, i.e. a parasite of other parasites, in the regulation of their fungal hosts' population dynamics. For this purpose, we first designed a quantitative PCR assay for detection of Ampelomyces spp. in field-collected samples. This newly developed molecular test was then applied to a large-scale sampling within the Åland archipelago, revealing that Ampelomyces is a widespread hyperparasite in this system, with high variability in prevalence among populations. We found that the hyperparasite was more common on leaves where multiple powdery mildew strains coexist, a pattern that may be attributed to differential exposure. Moreover, the prevalence of Ampelomyces at the plant level negatively affected the overwinter survival of its fungal host. We conclude that this hyperparasite may likely impact on its host population dynamics and argue for increased focus on the role of hyperparasites in disease dynamics. PMID:25204419

  8. A dynamic traffic simulator for roads affected by natural hasards

    NASA Astrophysics Data System (ADS)

    Voumard, J.; Jaboyedoff, M.; Derron, M.-H.

    2012-04-01

    This work focuses on the issue of natural hazards threatening roads. Nowadays, risk estimations of rock falls or landslides affecting whole sections of road are generally quite accurate and under relatively good control. Mitigation measures provide intervention means to reduce the hazards along roads. However, as classical models of risk calculation on communication routes do not take into account the dynamic traffic parameters, little is known on the way of reducing the risk at road level. It is not known precisely what really happens on the road when an event occurs and how vehicles interact. A dynamic traffic simulator in development provides information on factors having an impact on the risk level related to the road. Variables such as visibility, curvature radius of turns or vehicle type were included in the model. Varying these variables within dynamic traffic simulations can suggest solutions to minimize the risks for road users. These simulations can provide answers to various questions, such as: does speed have a significant impact on the risk incurred by drivers? Is it possible to significantly reduce the risk with appropriate speeds? The simulation is performed with the MATLAB © software. The model is yet to be calibrated and validated through in situ tests.

  9. Disease in a dynamic landscape: host behavior and wildfire reduce amphibian chytrid infection

    USGS Publications Warehouse

    Hossack, Blake R.; Lowe, Winsor H.; Ware, Joy L.; Corn, Paul Stephen

    2013-01-01

    Disturbances are often expected to magnify effects of disease, but these effects may depend on the ecology, behavior, and life history of both hosts and pathogens. In many ecosystems, wildfire is the dominant natural disturbance and thus could directly or indirectly affect dynamics of many diseases. To determine how probability of infection by the aquatic fungus Batrachochytrium dendrobatidis (Bd) varies relative to habitat use by individuals, wildfire, and host characteristics, we sampled 404 boreal toads (Anaxyrus boreas boreas) across Glacier National Park, Montana (USA). Bd causes chytridiomycosis, an emerging infectious disease linked with widespread amphibian declines, including the boreal toad. Probability of infection was similar for females and the combined group of males and juveniles. However, only 9% of terrestrial toads were infected compared to >30% of aquatic toads, and toads captured in recently burned areas were half as likely to be infected as toads in unburned areas. We suspect these large differences in infection reflect habitat choices by individuals that affect pathogen exposure and persistence, especially in burned forests where warm, arid conditions could limit Bd growth. Our results show that natural disturbances such as wildfire and the resulting diverse habitats can influence infection across large landscapes, potentially maintaining local refuges and host behaviors that facilitate evolution of disease resistance.

  10. Within-host viral dynamics of dengue serotype 1 infection.

    PubMed

    Clapham, Hannah E; Tricou, Vianney; Van Vinh Chau, Nguyen; Simmons, Cameron P; Ferguson, Neil M

    2014-07-01

    Dengue, the most common mosquito-borne viral infection of humans, is endemic across much of the world, including much of tropical Asia and is increasing in its geographical range. Here, we present a mathematical model of dengue virus dynamics within infected individuals, detailing the interaction between virus and a simple immune response. We fit this model to measurements of plasma viral titre from cases of primary and secondary DENV 1 infection in Vietnam. We show that variation in model parameters governing the immune response is sufficient to create the observed variation in virus dynamics between individuals. Estimating model parameter values, we find parameter differences between primary and secondary cases consistent with the theory of antibody-dependent enhancement (namely enhanced rates of viral entry to target cells in secondary cases). Finally, we use our model to examine the potential impact of an antiviral drug on the within-host dynamics of dengue. We conclude that the impact of antiviral therapy on virus dynamics is likely to be limited if therapy is only started at the onset of symptoms, owing to the typically late stage of viral pathogenesis reached by the time symptoms are manifested and thus treatment is started.

  11. Intracellular Demography and the Dynamics of Salmonella enterica Infections

    PubMed Central

    Sheppard, Mark; Grant, Andrew J; Maskell, Duncan J; Grenfell, Bryan T; Mastroeni, Pietro

    2006-01-01

    An understanding of within-host dynamics of pathogen interactions with eukaryotic cells can shape the development of effective preventive measures and drug regimes. Such investigations have been hampered by the difficulty of identifying and observing directly, within live tissues, the multiple key variables that underlay infection processes. Fluorescence microscopy data on intracellular distributions of Salmonella enterica serovar Typhimurium (S. Typhimurium) show that, while the number of infected cells increases with time, the distribution of bacteria between cells is stationary (though highly skewed). Here, we report a simple model framework for the intensity of intracellular infection that links the quasi-stationary distribution of bacteria to bacterial and cellular demography. This enables us to reject the hypothesis that the skewed distribution is generated by intrinsic cellular heterogeneities, and to derive specific predictions on the within-cell dynamics of Salmonella division and host-cell lysis. For within-cell pathogens in general, we show that within-cell dynamics have implications across pathogen dynamics, evolution, and control, and we develop novel generic guidelines for the design of antibacterial combination therapies and the management of antibiotic resistance. PMID:17048989

  12. Wolbachia-Host Interactions: Host Mating Patterns Affect Wolbachia Density Dynamics

    PubMed Central

    Zhao, Dong-Xiao; Zhang, Xiang-Fei; Chen, Da-Song; Zhang, Yan-Kai; Hong, Xiao-Yue

    2013-01-01

    Wolbachia are maternally inherited intracellular bacteria that infect a wide range of arthropods and cause an array of effects on host reproduction, fitness and mating behavior. Although our understanding of the Wolbachia-associated effects on hosts is rapidly expanding, our knowledge of the host factors that mediate Wolbachia dynamics is rudimentary. Here, we explore the interactions between Wolbachia and its host, the two-spotted spider mite Tetranychus urticae Koch. Our results indicate that Wolbachia induces strong cytoplasmic incompatibility (CI), increases host fecundity, but has no effects on the longevity of females and the mating competitiveness of males in T. urticae. Most importantly, host mating pattern was found to affect Wolbachia density dynamics during host aging. Mating of an uninfected mite of either sex with an infected mite attenuates the Wolbachia density in the infected mite. According to the results of Wolbachia localization, this finding may be associated with the tropism of Wolbachia for the reproductive tissue in adult spider mites. Our findings describe a new interaction between Wolbachia and their hosts. PMID:23823081

  13. Dynamics of the microbiota in response to host infection.

    PubMed

    Belzer, Clara; Gerber, Georg K; Roeselers, Guus; Delaney, Mary; DuBois, Andrea; Liu, Qing; Belavusava, Vera; Yeliseyev, Vladimir; Houseman, Andres; Onderdonk, Andrew; Cavanaugh, Colleen; Bry, Lynn

    2014-01-01

    Longitudinal studies of the microbiota are important for discovering changes in microbial communities that affect the host. The complexity of these ecosystems requires rigorous integrated experimental and computational methods to identify temporal signatures that promote physiologic or pathophysiologic responses in vivo. Employing a murine model of infectious colitis with the pathogen Citrobacter rodentium, we generated a 2-month time-series of 16S rDNA gene profiles, and quantitatively cultured commensals, from multiple intestinal sites in infected and uninfected mice. We developed a computational framework to discover time-varying signatures for individual taxa, and to automatically group signatures to identify microbial sub-communities within the larger gut ecosystem that demonstrate common behaviors. Application of this model to the 16S rDNA dataset revealed dynamic alterations in the microbiota at multiple levels of resolution, from effects on systems-level metrics to changes across anatomic sites for individual taxa and species. These analyses revealed unique, time-dependent microbial signatures associated with host responses at different stages of colitis. Signatures included a Mucispirillum OTU associated with early disruption of the colonic surface mucus layer, prior to the onset of symptomatic colitis, and members of the Clostridiales and Lactobacillales that increased with successful resolution of inflammation, after clearance of the pathogen. Quantitative culture data validated findings for predominant species, further refining and strengthening model predictions. These findings provide new insights into the complex behaviors found within host ecosystems, and define several time-dependent microbial signatures that may be leveraged in studies of other infectious or inflammatory conditions. PMID:25014551

  14. Dynamics of Cryphonectria hypovirus infection in chestnut blight cankers.

    PubMed

    Bryner, Sarah Franziska; Prospero, Simone; Rigling, Daniel

    2014-09-01

    Virulent strains of the chestnut blight fungus Cryphonectria parasitica cause lethal bark cankers on chestnut trees. Infection of C. parasitica with Cryphonectria hypovirus 1 in Europe biologically controls this disease, leading to nonlethal and inactive cankers. Unexpectedly, virus-free C. parasitica strains have been isolated from inactive cankers. In this study, we compared the virulence of virus-infected and virus-free C. parasitica strains isolated from either inactive or active cankers on chestnut seedlings and sprouts. In the seedling experiment, we assessed canker growth and seedling mortality. In the sprout experiment, we also assessed canker growth and made fungal reisolations to determine virus infection and immigration of foreign vegetative compatibility (vc) types over a period of 13 years in a coppice forest. Overall, the virulence of virus-free C. parasitica strains isolated from inactive versus active cankers did not differ. Significant differences were only attributed to virus infection. Virus infection and fungal strain composition in cankers changed over time. Foreign vc types immigrated into cankers and virus-free cankers became virus-infected within a few years. Most of the cankers were callused over time and became inactive. However, we observed that the virus did not always persist in these cankers. This study demonstrates that virus spread occurs effectively in European chestnut forests and that this biocontrol system is highly dynamic.

  15. Social ecological factors associated with future orientation of children affected by parental HIV infection and AIDS.

    PubMed

    Lin, Xiuyun; Fang, Xiaoyi; Chi, Peilian; Heath, Melissa Allen; Li, Xiaoming; Chen, Wenrui

    2016-07-01

    From a social ecological perspective, this study examined the effects of stigma (societal level), trusting relationships with current caregivers (familial level), and self-esteem (individual level) on future orientation of children affected by HIV infection and AIDS. Comparing self-report data from 1221 children affected by parental HIV infection and AIDS and 404 unaffected children, affected children reported greater stigma and lower future orientation, trusting relationships, and self-esteem. Based on structural equation modeling, stigma experiences, trusting relationships, and self-esteem had direct effects on future orientation, with self-esteem and trusting relationships partially mediating the effect of stigma experiences on children's future orientation. Implications are discussed.

  16. Integrated Metabolomics, Transcriptomics and Proteomics Identifies Metabolic Pathways Affected by Anaplasma phagocytophilum Infection in Tick Cells.

    PubMed

    Villar, Margarita; Ayllón, Nieves; Alberdi, Pilar; Moreno, Andrés; Moreno, María; Tobes, Raquel; Mateos-Hernández, Lourdes; Weisheit, Sabine; Bell-Sakyi, Lesley; de la Fuente, José

    2015-12-01

    Anaplasma phagocytophilum is an emerging zoonotic pathogen that causes human granulocytic anaplasmosis. These intracellular bacteria establish infection by affecting cell function in both the vertebrate host and the tick vector, Ixodes scapularis. Previous studies have characterized the tick transcriptome and proteome in response to A. phagocytophilum infection. However, in the postgenomic era, the integration of omics datasets through a systems biology approach allows network-based analyses to describe the complexity and functionality of biological systems such as host-pathogen interactions and the discovery of new targets for prevention and control of infectious diseases. This study reports the first systems biology integration of metabolomics, transcriptomics, and proteomics data to characterize essential metabolic pathways involved in the tick response to A. phagocytophilum infection. The ISE6 tick cells used in this study constitute a model for hemocytes involved in pathogen infection and immune response. The results showed that infection affected protein processing in endoplasmic reticulum and glucose metabolic pathways in tick cells. These results supported tick-Anaplasma co-evolution by providing new evidence of how tick cells limit pathogen infection, while the pathogen benefits from the tick cell response to establish infection. Additionally, ticks benefit from A. phagocytophilum infection by increasing survival while pathogens guarantee transmission. The results suggested that A. phagocytophilum induces protein misfolding to limit the tick cell response and facilitate infection but requires protein degradation to prevent ER stress and cell apoptosis to survive in infected cells. Additionally, A. phagocytophilum may benefit from the tick cell's ability to limit bacterial infection through PEPCK inhibition leading to decreased glucose metabolism, which also results in the inhibition of cell apoptosis that increases infection of tick cells. These results

  17. Dynamics and persistence of Mycoplasma hyopneumoniae infection in pigs.

    PubMed

    Fano, Eduardo; Pijoan, Carlos; Dee, Scott

    2005-07-01

    The purpose of this study was to describe the dynamics (shedding and transmission) of Mycoplasma hyopneumoniae infection within a population of swine and to determine the duration of the infection (persistence) through the identification of the agent in bronchial samples. Sixty-three 2-month-old pigs were used in this study. The pigs (n = 28) were experimentally infected by the intratracheal route with M. hyopneumoniae and considered as seeder pigs. The remaining pigs (n = 32) were not inoculated and randomly allocated to 2 different groups: direct contact exposure pigs (n = 12) and indirect contact exposure pigs (n = 20). Blood samples and nasal swabs were collected throughout the study on days 0, 28, 35, 42, 49, 63, 91, and 119 postinfection. To assess the duration of M. hyopneumoniae infection, 9 seeder and 6 contact exposure pigs were slaughtered at days 155 (group 1), 170 (group 2), and 185 (group 3) postinfection. Direct contact pigs showed evidence of infection on day 28 by polymerase chain reaction (PCR) and on day 35 by serology. The indirect contact exposure pigs presented a very delayed and slow seroconversion pattern; they did not present evidence of transmission until 42 d after the infection of seeder pigs. Identification of M. hyopneumoniae in bronchial swabs was confirmed by nested-PCR from days 155 to 185 postinfection. At the last slaughter date, 77.7% and 100% of the seeders and contact exposure pigs, respectively, tested positive. The results of this study reconfirmed direct infection of M. hyopneumoniae and suggest that indirect transmission can occur in a population. Finally, duration of the infection in this study was longer than previously described. PMID:16187553

  18. Revealing the dynamics of polymicrobial infections: implications for antibiotic therapy

    PubMed Central

    Rogers, Geraint B.; Hoffman, Lucas R.; Whiteley, Marvin; Daniels, Thomas W.V.; Carroll, Mary P.; Bruce, Kenneth D.

    2011-01-01

    As a new generation of culture-independent analytical strategies emerge, the amount of data on polymicrobial infections will increase dramatically. For these data to inform clinical thinking, and in turn to maximise benefits for patients, an appropriate framework for their interpretation is required. Here, we use cystic fibrosis (CF) lower airway infections as a model system to examine how conceptual and technological advances can address two clinical questions that are central to improved management of CF respiratory disease. Firstly, can markers of the microbial community be identified that predict a change in infection dynamics and clinical outcomes? Secondly, can these new strategies directly characterize the impact of antimicrobial therapies, allowing treatment efficacy to be both assessed and optimized? PMID:20554204

  19. Modeling dynamics of HIV infected cells using stochastic cellular automaton

    NASA Astrophysics Data System (ADS)

    Precharattana, Monamorn; Triampo, Wannapong

    2014-08-01

    Ever since HIV was first diagnosed in human, a great number of scientific works have been undertaken to explore the biological mechanisms involved in the infection and progression of the disease. Several cellular automata (CA) models have been introduced to gain insights into the dynamics of the disease progression but none of them has taken into account effects of certain immune cells such as the dendritic cells (DCs) and the CD8+ T lymphocytes (CD8+ T cells). In this work, we present a CA model, which incorporates effects of the HIV specific immune response focusing on the cell-mediated immunities, and investigate the interaction between the host immune response and the HIV infected cells in the lymph nodes. The aim of our work is to propose a model more realistic than the one in Precharattana et al. (2010) [10], by incorporating roles of the DCs, the CD4+ T cells, and the CD8+ T cells into the model so that it would reproduce the HIV infection dynamics during the primary phase of HIV infection.

  20. The model of fungal population dynamics affected by nystatin

    NASA Astrophysics Data System (ADS)

    Voychuk, Sergei I.; Gromozova, Elena N.; Sadovskiy, Mikhail G.

    Fungal diseases are acute problems of the up-to-day medicine. Significant increase of resistance of microorganisms to the medically used antibiotics and a lack of new effective drugs follows in a growth of dosage of existing chemicals to solve the problem. Quite often such approach results in side effects on humans. Detailed study of fungi-antibiotic dynamics can identify new mechanisms and bring new ideas to overcome the microbial resistance with a lower dosage of antibiotics. In this study, the dynamics of the microbial population under antibiotic treatment was investigated. The effects of nystatin on the population of Saccharomyces cerevisiae yeasts were used as a model system. Nystatin effects were investigated both in liquid and solid media by viability tests. Dependence of nystatin action on osmotic gradient was evaluated in NaCl solutions. Influences of glucose and yeast extract were additionally analyzed. A "stepwise" pattern of the cell death caused by nystatin was the most intriguing. This pattern manifested in periodical changes of the stages of cell death against stages of resistance to the antibiotic. The mathematical model was proposed to describe cell-antibiotic interactions and nystatin viability effects in the liquid medium. The model implies that antibiotic ability to cause a cells death is significantly affected by the intracellular compounds, which came out of cells after their osmotic barriers were damaged

  1. Factors affecting dynamical seasonal prediction of the Arctic sea ice

    NASA Astrophysics Data System (ADS)

    Wang, W.; Chen, M.; Kumar, A.; Hung, M.

    2013-12-01

    Arctic sea ice variability has received increasing attention during the last decade. Seasonal prediction of the Arctic sea ice has been primarily produced with statistical methods during the past years. A few operational centers have recently implemented dynamical sea ice component in the coupled atmosphere-ocean forecast systems for seasonal climate prediction. Yet various issues remain to be resolved for an improved prediction of seasonal sea ice variations. In this study, we analyze the forecast of sea ice extent in the NCEP Climate Forecast System version 2 (CFSv2) and address factors that affect the representation of the observed sea ice variability in the forecast model. The analysis will be based on retrospective and real-time 9-month forecasts from the CFSv2 for 1982-2012. We will first assess the overall performance of the CFSv2 in capturing the observed sea ice extent climatology, long-term trend, and interannual anomalies. We will then discuss factors that affect the sea ice prediction, including: (1) consistency of the initialization of the observed sea ice concentration, (2) impacts of surface heat fluxes related to atmospheric model physics, (3) bias in sea surface temperatures, and (4) impacts of initial sea ice thickness.

  2. Dynamics of alpha oscillations elucidate facial affect recognition in schizophrenia.

    PubMed

    Popov, Tzvetan G; Rockstroh, Brigitte S; Popova, Petia; Carolus, Almut M; Miller, Gregory A

    2014-03-01

    Impaired facial affect recognition is characteristic of schizophrenia and has been related to impaired social function, but the relevant neural mechanisms have not been fully identified. The present study sought to identify the role of oscillatory alpha activity in that deficit during the process of facial emotion recognition. Neuromagnetic brain activity was monitored while 44 schizophrenia patients and 44 healthy controls viewed 5-s videos showing human faces gradually changing from neutral to fearful or happy expressions or from the neutral face of one poser to the neutral face of another. Recognition performance was determined separately by self-report. Relative to prestimulus baseline, controls exhibited a 10- to 15-Hz power increase prior to full recognition and a 10- to 15-Hz power decrease during the postrecognition phase. These results support recent proposals about the function of alpha-band oscillations in normal stimulus evaluation. The patients failed to show this sequence of alpha power increase and decrease and also showed low 10- to 15-Hz power and high 10- to 15-Hz connectivity during the prestimulus baseline. In light of the proposal that a combination of alpha power increase and functional disconnection facilitates information intake and processing, the finding of an abnormal association of low baseline alpha power and high connectivity in schizophrenia suggests a state of impaired readiness that fosters abnormal dynamics during facial affect recognition.

  3. [Dynamics of the cell cycle in human endothelial cell culture infected with influenza virus].

    PubMed

    Prochukhanova, A R; Lyublinskaya, O G; Azarenok, A A; Nazarova, A V; Zenin, V V; Zhilinskaya, I N

    2015-01-01

    Cell cycle in a culture of endothelial cells EAhy 926 infected with influenza virus was investigated. Cytometric analysis of culture, synchronized using contact inhibition, has shown that the exposure to the influenza virus in cells EAhy 926 lengthened S-phase of the cell cycle. This result has been tested and proven on culture EAhy 926 treated with nocodazole. Compared with lung carcinoma cells A549, in which influenza virus provokes the arrest of G0/G1 phase of the cycle, elongation of S-phase of cycle at a similar infection of endothelial culture EAhy 926 indicates that the influenza virus differently affects the dynamics of the cell cycle according to the origin of the infected culture.

  4. HIV-1 requires Arf6-mediated membrane dynamics to efficiently enter and infect T lymphocytes

    PubMed Central

    García-Expósito, Laura; Barroso-González, Jonathan; Puigdomènech, Isabel; Machado, José-David; Blanco, Julià; Valenzuela-Fernández, Agustín

    2011-01-01

    As the initial barrier to viral entry, the plasma membrane along with the membrane trafficking machinery and cytoskeleton are of fundamental importance in the viral cycle. However, little is known about the contribution of plasma membrane dynamics during early human immunodeficiency virus type 1 (HIV-1) infection. Considering that ADP ribosylation factor 6 (Arf6) regulates cellular invasion via several microorganisms by coordinating membrane trafficking, our aim was to study the function of Arf6-mediated membrane dynamics on HIV-1 entry and infection of T lymphocytes. We observed that an alteration of the Arf6–guanosine 5′-diphosphate/guanosine 5′-triphosphate (GTP/GDP) cycle, by GDP-bound or GTP-bound inactive mutants or by specific Arf6 silencing, inhibited HIV-1 envelope–induced membrane fusion, entry, and infection of T lymphocytes and permissive cells, regardless of viral tropism. Furthermore, cell-to-cell HIV-1 transmission of primary human CD4+ T lymphocytes was inhibited by Arf6 knockdown. Total internal reflection fluorescence microscopy showed that Arf6 mutants provoked the accumulation of phosphatidylinositol-(4,5)-biphosphate–associated structures on the plasma membrane of permissive cells, without affecting CD4-viral attachment but impeding CD4-dependent HIV-1 entry. Arf6 silencing or its mutants did not affect fusion, entry, and infection of vesicular stomatitis virus G–pseudotyped viruses or ligand-induced CXCR4 or CCR5 endocytosis, both clathrin-dependent processes. Therefore we propose that efficient early HIV-1 infection of CD4+ T lymphocytes requires Arf6-coordinated plasma membrane dynamics that promote viral fusion and entry. PMID:21346189

  5. Targeted interventions required against genital ulcers in African countries worst affected by HIV infection.

    PubMed Central

    O'Farrell, N.

    2001-01-01

    It remains unclear why there is such marked variation in the severity of the human immunodeficiency virus (HIV) epidemic between African countries. The prevalence of HIV infection has reached high levels in many parts of southern Africa but in most countries of West Africa the levels are much lower. Although there is good evidence that sexually transmitted infections (STIs) and genital ulcers in particular facilitate heterosexual transmission of HIV, there is little comparative STI data from the African countries worst affected by HIV infection. A MEDLINE search covering the period 1966 to August 2000 using the keywords "sexually transmitted diseases", "genital ulcers" and "Africa" was performed to identify factors that might be relevant to the spread of HIV infection in countries with the highest prevalences of the virus. In the countries worst affected by HIV infection, the proportions of men and women with STI who had genital ulcers lay in the ranges 45-68% and 13-68%, respectively. The proportions were much lower in countries of West Africa than in those of southern Africa. The African countries worst affected by HIV infection should adopt a more specialized approach to STI control than hitherto and specifically target the high incidence of genital ulceration. Locally, technical STI committees should draw up country-specific guidelines taking into account the prevalence of the various causes of genital ulceration. In these countries, national AIDS control programmes and donor agencies should develop a specific focus for decreasing the incidence of genital ulcer disease. PMID:11436480

  6. Targeted interventions required against genital ulcers in African countries worst affected by HIV infection.

    PubMed

    O'Farrell, N

    2001-01-01

    It remains unclear why there is such marked variation in the severity of the human immunodeficiency virus (HIV) epidemic between African countries. The prevalence of HIV infection has reached high levels in many parts of southern Africa but in most countries of West Africa the levels are much lower. Although there is good evidence that sexually transmitted infections (STIs) and genital ulcers in particular facilitate heterosexual transmission of HIV, there is little comparative STI data from the African countries worst affected by HIV infection. A MEDLINE search covering the period 1966 to August 2000 using the keywords "sexually transmitted diseases", "genital ulcers" and "Africa" was performed to identify factors that might be relevant to the spread of HIV infection in countries with the highest prevalences of the virus. In the countries worst affected by HIV infection, the proportions of men and women with STI who had genital ulcers lay in the ranges 45-68% and 13-68%, respectively. The proportions were much lower in countries of West Africa than in those of southern Africa. The African countries worst affected by HIV infection should adopt a more specialized approach to STI control than hitherto and specifically target the high incidence of genital ulceration. Locally, technical STI committees should draw up country-specific guidelines taking into account the prevalence of the various causes of genital ulceration. In these countries, national AIDS control programmes and donor agencies should develop a specific focus for decreasing the incidence of genital ulcer disease.

  7. Schistosomiasis Does Not Affect the Outcome of HCV Infection in Genotype 4-Infected Patients

    PubMed Central

    Allam, Walaa R.; Barakat, Ahmed; Zakaria, Zainab; Galal, Gehan; Abdel-Ghafar, Tamer S.; El-Tabbakh, Mohamed; Mikhail, Nabiel; Waked, Imam; Abdelwahab, Sayed F.

    2014-01-01

    Although reports suggest that Schistosoma mansoni increases hepatitis C virus (HCV) morbidity and chronicity, its impact on HCV spontaneous resolution is not clear. HCV genotype, viral load, abdominal ultrasonographic findings, and HCV-specific cell-mediated immunity (CMI) were examined among 141 healthcare workers infected with HCV (68 workers with and 73 workers without S. mansoni). HCV genotype 4 was dominate, and viral loads were 2.62 ± 0.69 × 106 and 4.24 ± 1.4 × 106 IU/mL among patients with and without coinfection, respectively (P = 0.309); 23.5% with and 32.9% without coinfection had spontaneously resolved HCV infection (P = 0.297). Interferon-γ spot-forming cells/106 peripheral blood mononuclear cells among responding viremic patients with and without coinfection were 716 ± 194 and 587 ± 162, whereas among aviremic patients, it was 794 ± 272 and 365 ± 36 (P > 0.05), respectively. In conclusion, there was no statistical difference in HCV spontaneous resolution, viral load, liver pathology, or CMI in patients with or without S. mansoni coinfection, suggesting that it did not impact the outcome of HCV infection. PMID:24615138

  8. Comparative Proteomics Identifies Host Immune System Proteins Affected by Infection with Mycobacterium bovis.

    PubMed

    López, Vladimir; Villar, Margarita; Queirós, João; Vicente, Joaquín; Mateos-Hernández, Lourdes; Díez-Delgado, Iratxe; Contreras, Marinela; Alves, Paulo C; Alberdi, Pilar; Gortázar, Christian; de la Fuente, José

    2016-03-01

    Mycobacteria of the Mycobacterium tuberculosis complex (MTBC) greatly impact human and animal health worldwide. The mycobacterial life cycle is complex, and the mechanisms resulting in pathogen infection and survival in host cells are not fully understood. Eurasian wild boar (Sus scrofa) are natural reservoir hosts for MTBC and a model for mycobacterial infection and tuberculosis (TB). In the wild boar TB model, mycobacterial infection affects the expression of innate and adaptive immune response genes in mandibular lymph nodes and oropharyngeal tonsils, and biomarkers have been proposed as correlates with resistance to natural infection. However, the mechanisms used by mycobacteria to manipulate host immune response are not fully characterized. Our hypothesis is that the immune system proteins under-represented in infected animals, when compared to uninfected controls, are used by mycobacteria to guarantee pathogen infection and transmission. To address this hypothesis, a comparative proteomics approach was used to compare host response between uninfected (TB-) and M. bovis-infected young (TB+) and adult animals with different infection status [TB lesions localized in the head (TB+) or affecting multiple organs (TB++)]. The results identified host immune system proteins that play an important role in host response to mycobacteria. Calcium binding protein A9, Heme peroxidase, Lactotransferrin, Cathelicidin and Peptidoglycan-recognition protein were under-represented in TB+ animals when compared to uninfected TB- controls, but protein levels were higher as infection progressed in TB++ animals when compared to TB- and/or TB+ adult wild boar. MHCI was the only protein over-represented in TB+ adult wild boar when compared to uninfected TB- controls. The results reported here suggest that M. bovis manipulates host immune response by reducing the production of immune system proteins. However, as infection progresses, wild boar immune response recovers to limit pathogen

  9. Comparative Proteomics Identifies Host Immune System Proteins Affected by Infection with Mycobacterium bovis

    PubMed Central

    López, Vladimir; Villar, Margarita; Queirós, João; Vicente, Joaquín; Mateos-Hernández, Lourdes; Díez-Delgado, Iratxe; Contreras, Marinela; Alves, Paulo C.; Alberdi, Pilar; Gortázar, Christian; de la Fuente, José

    2016-01-01

    Mycobacteria of the Mycobacterium tuberculosis complex (MTBC) greatly impact human and animal health worldwide. The mycobacterial life cycle is complex, and the mechanisms resulting in pathogen infection and survival in host cells are not fully understood. Eurasian wild boar (Sus scrofa) are natural reservoir hosts for MTBC and a model for mycobacterial infection and tuberculosis (TB). In the wild boar TB model, mycobacterial infection affects the expression of innate and adaptive immune response genes in mandibular lymph nodes and oropharyngeal tonsils, and biomarkers have been proposed as correlates with resistance to natural infection. However, the mechanisms used by mycobacteria to manipulate host immune response are not fully characterized. Our hypothesis is that the immune system proteins under-represented in infected animals, when compared to uninfected controls, are used by mycobacteria to guarantee pathogen infection and transmission. To address this hypothesis, a comparative proteomics approach was used to compare host response between uninfected (TB-) and M. bovis-infected young (TB+) and adult animals with different infection status [TB lesions localized in the head (TB+) or affecting multiple organs (TB++)]. The results identified host immune system proteins that play an important role in host response to mycobacteria. Calcium binding protein A9, Heme peroxidase, Lactotransferrin, Cathelicidin and Peptidoglycan-recognition protein were under-represented in TB+ animals when compared to uninfected TB- controls, but protein levels were higher as infection progressed in TB++ animals when compared to TB- and/or TB+ adult wild boar. MHCI was the only protein over-represented in TB+ adult wild boar when compared to uninfected TB- controls. The results reported here suggest that M. bovis manipulates host immune response by reducing the production of immune system proteins. However, as infection progresses, wild boar immune response recovers to limit pathogen

  10. Comparative Proteomics Identifies Host Immune System Proteins Affected by Infection with Mycobacterium bovis.

    PubMed

    López, Vladimir; Villar, Margarita; Queirós, João; Vicente, Joaquín; Mateos-Hernández, Lourdes; Díez-Delgado, Iratxe; Contreras, Marinela; Alves, Paulo C; Alberdi, Pilar; Gortázar, Christian; de la Fuente, José

    2016-03-01

    Mycobacteria of the Mycobacterium tuberculosis complex (MTBC) greatly impact human and animal health worldwide. The mycobacterial life cycle is complex, and the mechanisms resulting in pathogen infection and survival in host cells are not fully understood. Eurasian wild boar (Sus scrofa) are natural reservoir hosts for MTBC and a model for mycobacterial infection and tuberculosis (TB). In the wild boar TB model, mycobacterial infection affects the expression of innate and adaptive immune response genes in mandibular lymph nodes and oropharyngeal tonsils, and biomarkers have been proposed as correlates with resistance to natural infection. However, the mechanisms used by mycobacteria to manipulate host immune response are not fully characterized. Our hypothesis is that the immune system proteins under-represented in infected animals, when compared to uninfected controls, are used by mycobacteria to guarantee pathogen infection and transmission. To address this hypothesis, a comparative proteomics approach was used to compare host response between uninfected (TB-) and M. bovis-infected young (TB+) and adult animals with different infection status [TB lesions localized in the head (TB+) or affecting multiple organs (TB++)]. The results identified host immune system proteins that play an important role in host response to mycobacteria. Calcium binding protein A9, Heme peroxidase, Lactotransferrin, Cathelicidin and Peptidoglycan-recognition protein were under-represented in TB+ animals when compared to uninfected TB- controls, but protein levels were higher as infection progressed in TB++ animals when compared to TB- and/or TB+ adult wild boar. MHCI was the only protein over-represented in TB+ adult wild boar when compared to uninfected TB- controls. The results reported here suggest that M. bovis manipulates host immune response by reducing the production of immune system proteins. However, as infection progresses, wild boar immune response recovers to limit pathogen

  11. Virus Multiplicity of Infection Affects Type I Interferon Subtype Induction Profiles and Interferon-Stimulated Genes

    PubMed Central

    Zaritsky, Luna A.; Bedsaul, Jacquelyn R.

    2015-01-01

    ABSTRACT Type I interferons (IFNs) are induced upon viral infection and important mediators of innate immunity. While there is 1 beta interferon (IFN-β) protein, there are 12 different IFN-α subtypes. It has been reported extensively that different viruses induce distinct patterns of IFN subtypes, but it has not been previously shown how the viral multiplicity of infection (MOI) can affect IFN induction. In this study, we discovered the novel finding that human U937 cells infected with 2 different concentrations of Sendai virus (SeV) induce 2 distinct type I IFN subtype profiles. Cells infected at the lower MOI induced more subtypes than cells infected at the higher MOI. We found that this was due to the extent of signaling through the IFN receptor (IFNAR). The cells infected at the lower viral MOI induced the IFNAR2-dependent IFN-α subtypes 4, 6, 7, 10, and 17, which were not induced in cells infected at higher virus concentrations. IFN-β and IFN-α1, -2, and -8 were induced in an IFNAR-independent manner in cells infected at both virus concentrations. IFN-α5, -14, -16, and -21 were induced in an IFNAR-dependent manner in cells infected at lower virus concentrations and in an IFNAR-independent manner in cells infected at higher virus concentrations. These differences in IFN subtype profiles in the 2 virus concentrations also resulted in distinct interferon-stimulated gene induction. These results present the novel finding that different viral MOIs differentially activate JAK/STAT signaling through the IFNAR, which greatly affects the profile of IFN subtypes that are induced. IMPORTANCE Type I IFNs are pleiotropic cytokines that are instrumental in combating viral diseases. Understanding how the individual subtypes are induced is important in developing strategies to block viral replication. Many studies have reported that different viruses induce distinct type I IFN subtype profiles due to differences in the way viruses are sensed in different cell types

  12. The challenges of modelling antibody repertoire dynamics in HIV infection

    SciTech Connect

    Luo, Shishi; Perelson, Alan S.

    2015-07-20

    Antibody affinity maturation by somatic hypermutation of B-cell immunoglobulin variable region genes has been studied for decades in various model systems using well-defined antigens. While much is known about the molecular details of the process, our understanding of the selective forces that generate affinity maturation are less well developed, particularly in the case of a co-evolving pathogen such as HIV. Despite this gap in understanding, high-throughput antibody sequence data are increasingly being collected to investigate the evolutionary trajectories of antibody lineages in HIV-infected individuals. Here, we review what is known in controlled experimental systems about the mechanisms underlying antibody selection and compare this to the observed temporal patterns of antibody evolution in HIV infection. In addition, we describe how our current understanding of antibody selection mechanisms leaves questions about antibody dynamics in HIV infection unanswered. Without a mechanistic understanding of antibody selection in the context of a co-evolving viral population, modelling and analysis of antibody sequences in HIV-infected individuals will be limited in their interpretation and predictive ability.

  13. The challenges of modelling antibody repertoire dynamics in HIV infection

    DOE PAGES

    Luo, Shishi; Perelson, Alan S.

    2015-07-20

    Antibody affinity maturation by somatic hypermutation of B-cell immunoglobulin variable region genes has been studied for decades in various model systems using well-defined antigens. While much is known about the molecular details of the process, our understanding of the selective forces that generate affinity maturation are less well developed, particularly in the case of a co-evolving pathogen such as HIV. Despite this gap in understanding, high-throughput antibody sequence data are increasingly being collected to investigate the evolutionary trajectories of antibody lineages in HIV-infected individuals. Here, we review what is known in controlled experimental systems about the mechanisms underlying antibody selectionmore » and compare this to the observed temporal patterns of antibody evolution in HIV infection. In addition, we describe how our current understanding of antibody selection mechanisms leaves questions about antibody dynamics in HIV infection unanswered. Without a mechanistic understanding of antibody selection in the context of a co-evolving viral population, modelling and analysis of antibody sequences in HIV-infected individuals will be limited in their interpretation and predictive ability.« less

  14. Wolbachia infections in natural Anopheles populations affect egg laying and negatively correlate with Plasmodium development

    PubMed Central

    Shaw, W. Robert; Marcenac, Perrine; Childs, Lauren M.; Buckee, Caroline O.; Baldini, Francesco; Sawadogo, Simon P.; Dabiré, Roch K.; Diabaté, Abdoulaye; Catteruccia, Flaminia

    2016-01-01

    The maternally inherited alpha-proteobacterium Wolbachia has been proposed as a tool to block transmission of devastating mosquito-borne infectious diseases like dengue and malaria. Here we study the reproductive manipulations induced by a recently identified Wolbachia strain that stably infects natural mosquito populations of a major malaria vector, Anopheles coluzzii, in Burkina Faso. We determine that these infections significantly accelerate egg laying but do not induce cytoplasmic incompatibility or sex-ratio distortion, two parasitic reproductive phenotypes that facilitate the spread of other Wolbachia strains within insect hosts. Analysis of 221 blood-fed A. coluzzii females collected from houses shows a negative correlation between the presence of Plasmodium parasites and Wolbachia infection. A mathematical model incorporating these results predicts that infection with these endosymbionts may reduce malaria prevalence in human populations. These data suggest that Wolbachia may be an important player in malaria transmission dynamics in Sub-Saharan Africa. PMID:27243367

  15. Spatio-temporal dynamics of parasites infecting Diporeia spp. (Amphipoda, Gammaridae) in southern Lake Michigan (USA).

    PubMed

    Winters, Andrew D; Fitzgerald, Scott; Brenden, Travis O; Nalepa, Thomas; Faisal, Mohamed

    2014-09-01

    Since the 1990s, populations of the benthic amphipod Diporeia spp. (Diporeia) have sharply declined across much of the Laurentian Great Lakes. This study was undertaken to identify contemporary and historical community composition, structure, and dynamics of parasites infecting Diporeia collected from nine sites in the southern basin of Lake Michigan, where declines of the amphipod have been well documented over the past 20years. An additional aim of this study was to assess whether infection dynamics and dreissenid densities could explain the declines in Diporeia densities that have occurred. We found that Diporeia were host to eight groups of uni- and multicellular pathogens. Of the 3082 amphipods analyzed, 1624 individuals (52.7%) were infected with at least one type of parasite. Ciliophora was the most prevalent parasite (50.08% prevalence of infection), followed by Gregarinasina (2.79%), Microsporidia (0.68%), Cestoda (0.45%), Acanthocephala (0.36%), Haplosporidia (0.23%), Yeast (0.32%), and filamentous Fungi (0.10%). Considerable spatial and temporal variability were observed in parasite prevalences, with prevalences frequently appearing to cycle between low and high values. Parasite species belonging to Microsporidia and Haplosporidia were associated with tissue alteration and host inflammatory response; however, parasite prevalences explained very little in terms of Diporeia density declines at assessed sites. Despite these findings, we do not discount the possibility that parasitic infections may have played a role in declining Diporeia densities in the Great Lakes, as the cyclical prevalences that were observed are possibly suggestive of parasitic outbreaks that are followed by die-offs at affected sites. This study suggests that if parasites have affected Diporeia densities in the Laurentian Great Lakes, then the relationship may be a complicated one.

  16. Spatio-temporal dynamics of parasites infecting Diporeia spp. (Amphipoda, Gammaridae) in southern Lake Michigan (USA).

    PubMed

    Winters, Andrew D; Fitzgerald, Scott; Brenden, Travis O; Nalepa, Thomas; Faisal, Mohamed

    2014-09-01

    Since the 1990s, populations of the benthic amphipod Diporeia spp. (Diporeia) have sharply declined across much of the Laurentian Great Lakes. This study was undertaken to identify contemporary and historical community composition, structure, and dynamics of parasites infecting Diporeia collected from nine sites in the southern basin of Lake Michigan, where declines of the amphipod have been well documented over the past 20years. An additional aim of this study was to assess whether infection dynamics and dreissenid densities could explain the declines in Diporeia densities that have occurred. We found that Diporeia were host to eight groups of uni- and multicellular pathogens. Of the 3082 amphipods analyzed, 1624 individuals (52.7%) were infected with at least one type of parasite. Ciliophora was the most prevalent parasite (50.08% prevalence of infection), followed by Gregarinasina (2.79%), Microsporidia (0.68%), Cestoda (0.45%), Acanthocephala (0.36%), Haplosporidia (0.23%), Yeast (0.32%), and filamentous Fungi (0.10%). Considerable spatial and temporal variability were observed in parasite prevalences, with prevalences frequently appearing to cycle between low and high values. Parasite species belonging to Microsporidia and Haplosporidia were associated with tissue alteration and host inflammatory response; however, parasite prevalences explained very little in terms of Diporeia density declines at assessed sites. Despite these findings, we do not discount the possibility that parasitic infections may have played a role in declining Diporeia densities in the Great Lakes, as the cyclical prevalences that were observed are possibly suggestive of parasitic outbreaks that are followed by die-offs at affected sites. This study suggests that if parasites have affected Diporeia densities in the Laurentian Great Lakes, then the relationship may be a complicated one. PMID:24991698

  17. Tick-Borne Encephalitis Virus Infects Rat Astrocytes but Does Not Affect Their Viability

    PubMed Central

    Potokar, Maja; Korva, Miša; Jorgačevski, Jernej; Avšič-Županc, Tatjana; Zorec, Robert

    2014-01-01

    Tick-borne encephalitis virus (TBEV) causes one of the most dangerous human neuroinfections in Europe and Asia. To infect neurons it must cross the blood-brain-barrier (BBB), and presumably also cells adjacent to the BBB, such as astrocytes, the most abundant glial cell type. However, the knowledge about the viral infection of glial cells is fragmental. Here we studied whether TBEV infects rat astrocytes. Rats belong to an animal group serving as a TBEV amplifying host. We employed high resolution quantitative fluorescence microscopy to investigate cell entry and cytoplasmic mobility of TBEV particles along with the effect on the cell cytoskeleton and cell survival. We report that infection of astrocytes with TBEV increases with time of exposure to TBEV and that with post-infection time TBEV particles gained higher mobility. After several days of infection actin cytoskeleton was affected, but cell survival was unchanged, indicating that rat astrocytes resist TBEV-mediated cell death, as reported for other mammalian cells. Therefore, astrocytes may present an important pool of dormant TBEV infections and a new target for therapeutic intervention. PMID:24465969

  18. Treatment of urodelans based on temperature dependent infection dynamics of Batrachochytrium salamandrivorans.

    PubMed

    Blooi, M; Martel, A; Haesebrouck, F; Vercammen, F; Bonte, D; Pasmans, F

    2015-01-27

    The recently emerged chytrid fungus Batrachochytrium salamandrivorans currently causes amphibian population declines. We hypothesized that temperature dictates infection dynamics of B. salamandrivorans, and that therefore heat treatment may be applied to clear animals from infection. We examined the impact of environmental temperature on B. salamandrivorans infection and disease dynamics in fire salamanders (Salamandra salamandra). Colonization of salamanders by B. salamandrivorans occurred at 15°C and 20°C but not at 25°C, with a significantly faster buildup of infection load and associated earlier mortality at 15°C. Exposing B. salamandrivorans infected salamanders to 25°C for 10 days resulted in complete clearance of infection and clinically cured all experimentally infected animals. This treatment protocol was validated in naturally infected wild fire salamanders. In conclusion, we show that B. salamandrivorans infection and disease dynamics are significantly dictated by environmental temperature, and that heat treatment is a viable option for clearing B. salamandrivorans infections.

  19. Dairy goat demography and Q fever infection dynamics

    PubMed Central

    2013-01-01

    Between 2007 and 2009, the largest human Q fever epidemic ever described occurred in the Netherlands. The source was traced back to dairy goat farms, where abortion storms had been observed since 2005. Since one putative cause of these abortion storms is the intensive husbandry systems in which the goats are kept, the objective of this study was to assess whether these could be explained by herd size, reproductive pattern and other demographic aspects of Dutch dairy goat herds alone. We adapted an existing, fully parameterized simulation model for Q fever transmission in French dairy cattle herds to represent the demographics typical for Dutch dairy goat herds. The original model represents the infection dynamics in a herd of 50 dairy cows after introduction of a single infected animal; the adapted model has 770 dairy goats. For a full comparison, herds of 770 cows and 50 goats were also modeled. The effects of herd size and goat versus cattle demographics on the probability of and time to extinction of the infection, environmental bacterial load and abortion rate were studied by simulation. The abortion storms could not be fully explained by demographics alone. Adequate data were lacking at the moment to attribute the difference to characteristics of the pathogen, host, within-herd environment, or a combination thereof. The probability of extinction was higher in goat herds than in cattle herds of the same size. The environmental contamination was highest within cattle herds, which may be taken into account when enlarging cattle farming systems. PMID:23621908

  20. Insight on Genes Affecting Tuber Development in Potato upon Potato spindle tuber viroid (PSTVd) Infection.

    PubMed

    Katsarou, Konstantina; Wu, Yun; Zhang, Runxuan; Bonar, Nicola; Morris, Jenny; Hedley, Pete E; Bryan, Glenn J; Kalantidis, Kriton; Hornyik, Csaba

    2016-01-01

    Potato (Solanum tuberosum L) is a natural host of Potato spindle tuber viroid (PSTVd) which can cause characteristic symptoms on developing plants including stunting phenotype and distortion of leaves and tubers. PSTVd is the type species of the family Pospiviroidae, and can replicate in the nucleus and move systemically throughout the plant. It is not well understood how the viroid can affect host genes for successful invasion and which genes show altered expression levels upon infection. Our primary focus in this study is the identification of genes which can affect tuber formation since viroid infection can strongly influence tuber development and especially tuber shape. In this study, we used a large-scale method to identify differentially expressed genes in potato. We have identified defence, stress and sugar metabolism related genes having altered expression levels upon infection. Additionally, hormone pathway related genes showed significant up- or down-regulation. DWARF1/DIMINUTO, Gibberellin 7-oxidase and BEL5 transcripts were identified and validated showing differential expression in viroid infected tissues. Our study suggests that gibberellin and brassinosteroid pathways have a possible role in tuber development upon PSTVd infection.

  1. Insight on Genes Affecting Tuber Development in Potato upon Potato spindle tuber viroid (PSTVd) Infection

    PubMed Central

    Zhang, Runxuan; Bonar, Nicola; Morris, Jenny; Hedley, Pete E.; Bryan, Glenn J.; Kalantidis, Kriton; Hornyik, Csaba

    2016-01-01

    Potato (Solanum tuberosum L) is a natural host of Potato spindle tuber viroid (PSTVd) which can cause characteristic symptoms on developing plants including stunting phenotype and distortion of leaves and tubers. PSTVd is the type species of the family Pospiviroidae, and can replicate in the nucleus and move systemically throughout the plant. It is not well understood how the viroid can affect host genes for successful invasion and which genes show altered expression levels upon infection. Our primary focus in this study is the identification of genes which can affect tuber formation since viroid infection can strongly influence tuber development and especially tuber shape. In this study, we used a large-scale method to identify differentially expressed genes in potato. We have identified defence, stress and sugar metabolism related genes having altered expression levels upon infection. Additionally, hormone pathway related genes showed significant up- or down-regulation. DWARF1/DIMINUTO, Gibberellin 7-oxidase and BEL5 transcripts were identified and validated showing differential expression in viroid infected tissues. Our study suggests that gibberellin and brassinosteroid pathways have a possible role in tuber development upon PSTVd infection. PMID:26937634

  2. Insight on Genes Affecting Tuber Development in Potato upon Potato spindle tuber viroid (PSTVd) Infection.

    PubMed

    Katsarou, Konstantina; Wu, Yun; Zhang, Runxuan; Bonar, Nicola; Morris, Jenny; Hedley, Pete E; Bryan, Glenn J; Kalantidis, Kriton; Hornyik, Csaba

    2016-01-01

    Potato (Solanum tuberosum L) is a natural host of Potato spindle tuber viroid (PSTVd) which can cause characteristic symptoms on developing plants including stunting phenotype and distortion of leaves and tubers. PSTVd is the type species of the family Pospiviroidae, and can replicate in the nucleus and move systemically throughout the plant. It is not well understood how the viroid can affect host genes for successful invasion and which genes show altered expression levels upon infection. Our primary focus in this study is the identification of genes which can affect tuber formation since viroid infection can strongly influence tuber development and especially tuber shape. In this study, we used a large-scale method to identify differentially expressed genes in potato. We have identified defence, stress and sugar metabolism related genes having altered expression levels upon infection. Additionally, hormone pathway related genes showed significant up- or down-regulation. DWARF1/DIMINUTO, Gibberellin 7-oxidase and BEL5 transcripts were identified and validated showing differential expression in viroid infected tissues. Our study suggests that gibberellin and brassinosteroid pathways have a possible role in tuber development upon PSTVd infection. PMID:26937634

  3. Ascaridia galli infection affects pullets differently when feed is contaminated with the Fusarium toxin deoxynivalenol (DON).

    PubMed

    Dänicke, S; Beineke, A; Rautenschlein, Silke; Valenta, Hana; Kersten, Susanne; Gauly, M

    2013-12-01

    The Fusarium mycotoxin deoxynivalenol (DON) is a common contaminant of cereal grains used as animal feed. DON is known for its cytotoxic and anti-proliferative properties and might adversely affect the health of poultry. The prevalence of the intestinal parasitizing roundworm Ascaridia galli is higher in outdoor housing systems and has been associated with maldigestion and malabsorption. It was hypothesized that ingested DON might not only affect the pullet itself but could also act on the nematode parasitizing in the ingesta. To examine these interactions between A. galli infection and DON contamination of feed 4 groups of 9 pullets in each were tested; non-infected groups were fed either an uncontaminated control (CON-) or a Fusarium toxin contaminated and mainly DON-containing diet (FUS-), and the corresponding A. galli inoculated groups were fed accordingly (CON+, FUS+). A. galli infection significantly reduced the jejunal villi height and increased the thickness of the tunica muscularis with the effect being more pronounced when the DON-containing diet was fed (Group FUS+). Only in this group significantly increased weights of jejunal and ileal tissues and of livers were noticed. Moreover, DON was detected in plasma of the pullets at higher frequencies when they were infected suggesting a facilitated absorption of DON. Group FUS+ was characterized by a significantly higher excretion of A. galli eggs and a concomitant lower proportion of pullets with detectable antibodies against a somatic antigen of A. galli while worm burden and worm characteristics were not affected by diet. Other effects of feeding the FUS diet to the infected pullets included an increased mass per length of male worms. In conclusion, infection of pullets with A. galli might increase the susceptibility towards DON as indicated by an increased DON absorption rate and a compromised antibody formation. The effects of DON on fecundity and worm morphology require further examination. PMID

  4. Ascaridia galli infection affects pullets differently when feed is contaminated with the Fusarium toxin deoxynivalenol (DON).

    PubMed

    Dänicke, S; Beineke, A; Rautenschlein, Silke; Valenta, Hana; Kersten, Susanne; Gauly, M

    2013-12-01

    The Fusarium mycotoxin deoxynivalenol (DON) is a common contaminant of cereal grains used as animal feed. DON is known for its cytotoxic and anti-proliferative properties and might adversely affect the health of poultry. The prevalence of the intestinal parasitizing roundworm Ascaridia galli is higher in outdoor housing systems and has been associated with maldigestion and malabsorption. It was hypothesized that ingested DON might not only affect the pullet itself but could also act on the nematode parasitizing in the ingesta. To examine these interactions between A. galli infection and DON contamination of feed 4 groups of 9 pullets in each were tested; non-infected groups were fed either an uncontaminated control (CON-) or a Fusarium toxin contaminated and mainly DON-containing diet (FUS-), and the corresponding A. galli inoculated groups were fed accordingly (CON+, FUS+). A. galli infection significantly reduced the jejunal villi height and increased the thickness of the tunica muscularis with the effect being more pronounced when the DON-containing diet was fed (Group FUS+). Only in this group significantly increased weights of jejunal and ileal tissues and of livers were noticed. Moreover, DON was detected in plasma of the pullets at higher frequencies when they were infected suggesting a facilitated absorption of DON. Group FUS+ was characterized by a significantly higher excretion of A. galli eggs and a concomitant lower proportion of pullets with detectable antibodies against a somatic antigen of A. galli while worm burden and worm characteristics were not affected by diet. Other effects of feeding the FUS diet to the infected pullets included an increased mass per length of male worms. In conclusion, infection of pullets with A. galli might increase the susceptibility towards DON as indicated by an increased DON absorption rate and a compromised antibody formation. The effects of DON on fecundity and worm morphology require further examination.

  5. A Hierarchical Latent Stochastic Differential Equation Model for Affective Dynamics

    ERIC Educational Resources Information Center

    Oravecz, Zita; Tuerlinckx, Francis; Vandekerckhove, Joachim

    2011-01-01

    In this article a continuous-time stochastic model (the Ornstein-Uhlenbeck process) is presented to model the perpetually altering states of the core affect, which is a 2-dimensional concept underlying all our affective experiences. The process model that we propose can account for the temporal changes in core affect on the latent level. The key…

  6. Dynamics and effects of Ligula intestinalis (L.) infection in the native fish Barbus callensis Valenciennes, 1842 in Algeria.

    PubMed

    Rouis, Sonia Ould; Rouis, Abdelhalim Ould; Dumont, Henri J; Magellan, Kit; Arab, Abdeslem

    2016-03-01

    The dynamics of the emergence, duration, and decline phases in epizootic cycles are well known for humans and some crops, but they are poorly understood for host-parasite systems in the wild. Parasites may be particularly insidious as they are often introduced unintentionally, simultaneously with their hosts, and later transferred to species in the new location. Here we investigate the epizootic dynamics of the tapeworm Ligula intestinalis in the Hamiz reservoir, Algeria, and explore its effects on the cyprinid fish Barbus callensis. Regular sampling was conducted from October 2005 to February 2008 with intermittent surveys carried out until 2010. Five percent of the 566 specimens of B. callensis that were caught were infected, with the maximum number of parasites found in spring. There was no obvious difference in weight between uninfected fish and infected ones, and infection did not affect fish condition. However, infected fish were significantly longer than uninfected fish and had inhibited gonad development. The proportion of infected fish caught was significantly higher in year 1 and by the second winter, infection collapsed to zero. The Ligula infection thus appeared to have minimal ecological effects and be of a temporary nature, thus exhibiting an epizootic cycle. Taken together, our data indicates that this infection declined or even failed during our study period. Failure may be due to the specific genetic strain of Ligula, but invasive carp may also have been influential in both the introduction and subsequent decline of this parasite.

  7. Dynamics and effects of Ligula intestinalis (L.) infection in the native fish Barbus callensis Valenciennes, 1842 in Algeria.

    PubMed

    Rouis, Sonia Ould; Rouis, Abdelhalim Ould; Dumont, Henri J; Magellan, Kit; Arab, Abdeslem

    2016-03-01

    The dynamics of the emergence, duration, and decline phases in epizootic cycles are well known for humans and some crops, but they are poorly understood for host-parasite systems in the wild. Parasites may be particularly insidious as they are often introduced unintentionally, simultaneously with their hosts, and later transferred to species in the new location. Here we investigate the epizootic dynamics of the tapeworm Ligula intestinalis in the Hamiz reservoir, Algeria, and explore its effects on the cyprinid fish Barbus callensis. Regular sampling was conducted from October 2005 to February 2008 with intermittent surveys carried out until 2010. Five percent of the 566 specimens of B. callensis that were caught were infected, with the maximum number of parasites found in spring. There was no obvious difference in weight between uninfected fish and infected ones, and infection did not affect fish condition. However, infected fish were significantly longer than uninfected fish and had inhibited gonad development. The proportion of infected fish caught was significantly higher in year 1 and by the second winter, infection collapsed to zero. The Ligula infection thus appeared to have minimal ecological effects and be of a temporary nature, thus exhibiting an epizootic cycle. Taken together, our data indicates that this infection declined or even failed during our study period. Failure may be due to the specific genetic strain of Ligula, but invasive carp may also have been influential in both the introduction and subsequent decline of this parasite. PMID:27078654

  8. Live Imaging of Influenza Infection of the Trachea Reveals Dynamic Regulation of CD8+ T Cell Motility by Antigen

    PubMed Central

    Lambert Emo, Kris; Hyun, Young-min; Barilla, Christopher; Gerber, Scott; Fowell, Deborah; Kim, Minsoo

    2016-01-01

    During a primary influenza infection, cytotoxic CD8+ T cells need to infiltrate the infected airways and engage virus-infected epithelial cells. The factors that regulate T cell motility in the infected airway tissue are not well known. To more precisely study T cell infiltration of the airways, we developed an experimental model system using the trachea as a site where live imaging can be performed. CD8+ T cell motility was dynamic with marked changes in motility on different days of the infection. In particular, significant changes in average cell velocity and confinement were evident on days 8–10 during which the T cells abruptly but transiently increase velocity on day 9. Experiments to distinguish whether infection itself or antigen affect motility revealed that it is antigen, not active infection per se that likely affects these changes as blockade of peptide/MHC resulted in increased velocity. These observations demonstrate that influenza tracheitis provides a robust experimental foundation to study molecular regulation of T cell motility during acute virus infection. PMID:27644089

  9. Live Imaging of Influenza Infection of the Trachea Reveals Dynamic Regulation of CD8+ T Cell Motility by Antigen.

    PubMed

    Lambert Emo, Kris; Hyun, Young-Min; Reilly, Emma; Barilla, Christopher; Gerber, Scott; Fowell, Deborah; Kim, Minsoo; Topham, David J

    2016-09-01

    During a primary influenza infection, cytotoxic CD8+ T cells need to infiltrate the infected airways and engage virus-infected epithelial cells. The factors that regulate T cell motility in the infected airway tissue are not well known. To more precisely study T cell infiltration of the airways, we developed an experimental model system using the trachea as a site where live imaging can be performed. CD8+ T cell motility was dynamic with marked changes in motility on different days of the infection. In particular, significant changes in average cell velocity and confinement were evident on days 8-10 during which the T cells abruptly but transiently increase velocity on day 9. Experiments to distinguish whether infection itself or antigen affect motility revealed that it is antigen, not active infection per se that likely affects these changes as blockade of peptide/MHC resulted in increased velocity. These observations demonstrate that influenza tracheitis provides a robust experimental foundation to study molecular regulation of T cell motility during acute virus infection. PMID:27644089

  10. Understanding myxozoan infection dynamics in the sea: seasonality and transmission of Ceratomyxa puntazzi.

    PubMed

    Alama-Bermejo, Gema; Šíma, Radek; Raga, Juan A; Holzer, Astrid S

    2013-08-01

    Ceratomyxa puntazzi affects the sharpsnout seabream, Diplodus puntazzo, a recently explored aquaculture species in the Mediterranean. Little is known about the transmission and seasonality of marine myxozoans, although this knowledge is of considerable importance for the design of management strategies for aquaculture. In the present study on C. puntazzi we investigated the potential pathways of transmission as well as the parasite abundance in fish and its density in environmental water samples, throughout a full year. We performed monthly sentinel fish exposures in a C. puntazzi enzootic environment and quantified waterborne stages in seawater. Two novel C. puntazzi-specific PCR and quantitative PCR assays were developed to determine infection levels in fish and water samples. Ceratomyxa puntazzi presents marked seasonal changes in parasite density, with a double-peaked prevalence of infection in sentinel fish in spring and late summer/autumn, at 16-24°C, and a covert infection during the winter months. Invasive blood stages were detected all year round by PCR. The combination of sentinel fish exposure with the quantification of waterborne stages allowed us to attribute this pattern in C. puntazzi density to higher numbers of actinospores in the water, while myxospores are predominant in summer and winter. We demonstrated that temperature increase triggered actinospore production in the invertebrate host in a benthic habitat and we suggest that the life cycle dynamics of the invertebrate host explain the double-peaked infection prevalence in fish. Experimental transmission of different C. puntazzi developmental stages in seawater or by oral and intracoelomic injection was unsuccessful which indicates fish-to-fish transmission is unlikely to occur in aquaculture systems. This is the first model studying seasonality and infection dynamics of a marine myxozoan.

  11. Understanding myxozoan infection dynamics in the sea: seasonality and transmission of Ceratomyxa puntazzi.

    PubMed

    Alama-Bermejo, Gema; Šíma, Radek; Raga, Juan A; Holzer, Astrid S

    2013-08-01

    Ceratomyxa puntazzi affects the sharpsnout seabream, Diplodus puntazzo, a recently explored aquaculture species in the Mediterranean. Little is known about the transmission and seasonality of marine myxozoans, although this knowledge is of considerable importance for the design of management strategies for aquaculture. In the present study on C. puntazzi we investigated the potential pathways of transmission as well as the parasite abundance in fish and its density in environmental water samples, throughout a full year. We performed monthly sentinel fish exposures in a C. puntazzi enzootic environment and quantified waterborne stages in seawater. Two novel C. puntazzi-specific PCR and quantitative PCR assays were developed to determine infection levels in fish and water samples. Ceratomyxa puntazzi presents marked seasonal changes in parasite density, with a double-peaked prevalence of infection in sentinel fish in spring and late summer/autumn, at 16-24°C, and a covert infection during the winter months. Invasive blood stages were detected all year round by PCR. The combination of sentinel fish exposure with the quantification of waterborne stages allowed us to attribute this pattern in C. puntazzi density to higher numbers of actinospores in the water, while myxospores are predominant in summer and winter. We demonstrated that temperature increase triggered actinospore production in the invertebrate host in a benthic habitat and we suggest that the life cycle dynamics of the invertebrate host explain the double-peaked infection prevalence in fish. Experimental transmission of different C. puntazzi developmental stages in seawater or by oral and intracoelomic injection was unsuccessful which indicates fish-to-fish transmission is unlikely to occur in aquaculture systems. This is the first model studying seasonality and infection dynamics of a marine myxozoan. PMID:23747926

  12. Bipolar disorder dynamics: affective instabilities, relaxation oscillations and noise

    PubMed Central

    Geddes, John R.; Goodwin, Guy M.; Holmes, Emily A.

    2015-01-01

    Bipolar disorder is a chronic, recurrent mental illness characterized by extreme episodes of depressed and manic mood, interspersed with less severe but highly variable mood fluctuations. Here, we develop a novel mathematical approach for exploring the dynamics of bipolar disorder. We investigate how the dynamics of subjective experience of mood in bipolar disorder can be understood using a relaxation oscillator (RO) framework and test the model against mood time-series fluctuations from a set of individuals with bipolar disorder. We show that variable mood fluctuations in individuals diagnosed with bipolar disorder can be driven by the coupled effects of deterministic dynamics (captured by ROs) and noise. Using a statistical likelihood-based approach, we show that, in general, mood dynamics are described by two independent ROs with differing levels of endogenous variability among individuals. We suggest that this sort of nonlinear approach to bipolar disorder has neurobiological, cognitive and clinical implications for understanding this mental illness through a mechacognitive framework. PMID:26577592

  13. Does Leisure Time as a Stress Coping Resource Increase Affective Complexity? Applying the Dynamic Model of Affect (DMA).

    PubMed

    Qian, Xinyi Lisa; Yarnal, Careen M; Almeida, David M

    2013-01-01

    Affective complexity, a manifestation of psychological well-being, refers to the relative independence between positive and negative affect (PA, NA). According to the Dynamic Model of Affect (DMA), stressful situations lead to highly inverse PA-NA relationship, reducing affective complexity. Meanwhile, positive events can sustain affective complexity by restoring PA-NA independence. Leisure, a type of positive events, has been identified as a coping resource. This study used the DMA to assess whether leisure time helps restore affective complexity on stressful days. We found that on days with more leisure time than usual, an individual experienced less negative PA-NA relationship after daily stressful events. The finding demonstrates the value of leisure time as a coping resource and the DMA's contribution to coping research. PMID:24659826

  14. Does Leisure Time as a Stress Coping Resource Increase Affective Complexity? Applying the Dynamic Model of Affect (DMA)

    PubMed Central

    Qian, Xinyi (Lisa); Yarnal, Careen M.; Almeida, David M.

    2013-01-01

    Affective complexity, a manifestation of psychological well-being, refers to the relative independence between positive and negative affect (PA, NA). According to the Dynamic Model of Affect (DMA), stressful situations lead to highly inverse PA-NA relationship, reducing affective complexity. Meanwhile, positive events can sustain affective complexity by restoring PA-NA independence. Leisure, a type of positive events, has been identified as a coping resource. This study used the DMA to assess whether leisure time helps restore affective complexity on stressful days. We found that on days with more leisure time than usual, an individual experienced less negative PA-NA relationship after daily stressful events. The finding demonstrates the value of leisure time as a coping resource and the DMA’s contribution to coping research. PMID:24659826

  15. Viral infection affects sucrose responsiveness and homing ability of forager honey bees, Apis mellifera L.

    PubMed

    Li, Zhiguo; Chen, Yanping; Zhang, Shaowu; Chen, Shenglu; Li, Wenfeng; Yan, Limin; Shi, Liangen; Wu, Lyman; Sohr, Alex; Su, Songkun

    2013-01-01

    Honey bee health is mainly affected by Varroa destructor, viruses, Nosema spp., pesticide residues and poor nutrition. Interactions between these proposed factors may be responsible for the colony losses reported worldwide in recent years. In the present study, the effects of a honey bee virus, Israeli acute paralysis virus (IAPV), on the foraging behaviors and homing ability of European honey bees (Apis mellifera L.) were investigated based on proboscis extension response (PER) assays and radio frequency identification (RFID) systems. The pollen forager honey bees originated from colonies that had no detectable level of honey bee viruses and were manually inoculated with IAPV to induce the viral infection. The results showed that IAPV-inoculated honey bees were more responsive to low sucrose solutions compared to that of non-infected foragers. After two days of infection, around 10⁷ copies of IAPV were detected in the heads of these honey bees. The homing ability of IAPV-infected foragers was depressed significantly in comparison to the homing ability of uninfected foragers. The data provided evidence that IAPV infection in the heads may enable the virus to disorder foraging roles of honey bees and to interfere with brain functions that are responsible for learning, navigation, and orientation in the honey bees, thus, making honey bees have a lower response threshold to sucrose and lose their way back to the hive. PMID:24130876

  16. Viral infection affects sucrose responsiveness and homing ability of forager honey bees, Apis mellifera L.

    PubMed

    Li, Zhiguo; Chen, Yanping; Zhang, Shaowu; Chen, Shenglu; Li, Wenfeng; Yan, Limin; Shi, Liangen; Wu, Lyman; Sohr, Alex; Su, Songkun

    2013-01-01

    Honey bee health is mainly affected by Varroa destructor, viruses, Nosema spp., pesticide residues and poor nutrition. Interactions between these proposed factors may be responsible for the colony losses reported worldwide in recent years. In the present study, the effects of a honey bee virus, Israeli acute paralysis virus (IAPV), on the foraging behaviors and homing ability of European honey bees (Apis mellifera L.) were investigated based on proboscis extension response (PER) assays and radio frequency identification (RFID) systems. The pollen forager honey bees originated from colonies that had no detectable level of honey bee viruses and were manually inoculated with IAPV to induce the viral infection. The results showed that IAPV-inoculated honey bees were more responsive to low sucrose solutions compared to that of non-infected foragers. After two days of infection, around 10⁷ copies of IAPV were detected in the heads of these honey bees. The homing ability of IAPV-infected foragers was depressed significantly in comparison to the homing ability of uninfected foragers. The data provided evidence that IAPV infection in the heads may enable the virus to disorder foraging roles of honey bees and to interfere with brain functions that are responsible for learning, navigation, and orientation in the honey bees, thus, making honey bees have a lower response threshold to sucrose and lose their way back to the hive.

  17. Viral Infection Affects Sucrose Responsiveness and Homing Ability of Forager Honey Bees, Apis mellifera L.

    PubMed Central

    Li, Zhiguo; Chen, Yanping; Zhang, Shaowu; Chen, Shenglu; Li, Wenfeng; Yan, Limin; Shi, Liangen; Wu, Lyman; Sohr, Alex; Su, Songkun

    2013-01-01

    Honey bee health is mainly affected by Varroa destructor, viruses, Nosema spp., pesticide residues and poor nutrition. Interactions between these proposed factors may be responsible for the colony losses reported worldwide in recent years. In the present study, the effects of a honey bee virus, Israeli acute paralysis virus (IAPV), on the foraging behaviors and homing ability of European honey bees (Apis mellifera L.) were investigated based on proboscis extension response (PER) assays and radio frequency identification (RFID) systems. The pollen forager honey bees originated from colonies that had no detectable level of honey bee viruses and were manually inoculated with IAPV to induce the viral infection. The results showed that IAPV-inoculated honey bees were more responsive to low sucrose solutions compared to that of non-infected foragers. After two days of infection, around 107 copies of IAPV were detected in the heads of these honey bees. The homing ability of IAPV-infected foragers was depressed significantly in comparison to the homing ability of uninfected foragers. The data provided evidence that IAPV infection in the heads may enable the virus to disorder foraging roles of honey bees and to interfere with brain functions that are responsible for learning, navigation, and orientation in the honey bees, thus, making honey bees have a lower response threshold to sucrose and lose their way back to the hive. PMID:24130876

  18. Environmental colour affects aspects of single-species population dynamics.

    PubMed

    Petchey, O L

    2000-04-22

    Single-species populations of ciliates (Colpidium and Paramecium) experienced constant temperature or white or reddened temperature fluctuations in aquatic microcosms in order to test three hypotheses about how environmental colour influences population dynamics. (i) Models predict that the colour of population dynamics is tinged by the colour of the environmental variability. However, environmental colour had no effect on the colour of population dynamics. All population dynamics in this experiment were reddened, regardless of environmental colour. (ii) Models predict that populations will track reddened environmental variability more closely than white environmental variability and that populations with a higher intrinsic growth rate (r) will track environmental variability more closely than populations with a low r. The experimental populations behaved as predicted. (iii) Models predict that population variability is determined by interaction between r and the environmental variability. The experimental populations behaved as predicted. These results show that (i) reddened population dynamics may need no special explanation, such as reddened environments, spatial subdivision or interspecific interactions, and (ii) and (iii) that population dynamics are sensitive to environmental colour, in agreement with population models. Correct specification of the colour of the environmental variability in models is required for accurate predictions. Further work is needed to study the effects of environmental colour on communities and ecosystems.

  19. Antagonism between two intestinal parasites in humans: the importance of co-infection for infection risk and recovery dynamics

    PubMed Central

    Blackwell, Aaron D.; Martin, Melanie; Kaplan, Hillard; Gurven, Michael

    2013-01-01

    Co-infection may affect transmission and recovery from infection, but remains an understudied element of disease ecology, particularly with regard to antagonism between parasites sharing a host. Helminth and giardia infections are often endemic in the same populations and both occupy the small intestine; yet few studies have examined interactions between these parasites. We report on helminth–giardia co-infections in a panel study of forager–horticulturalists in the Bolivian lowlands. Parasites were identified in faecal samples from 3275 participants, collected during 5235 medical exams over 6 years. Longitudinal co-infection patterns were examined using logistic mixed and multi-state Markov models. The most prevalent infections were hookworm (56%), Giardia lamblia (30%) and Ascaris lumbricoides (15%). Cross-sectionally, hookworm and A. lumbricoides were negatively associated with G. lamblia (OR = 0.60; OR = 0.65, respectively). Longitudinally, giardia infection was less likely in helminth-infected individuals (HR: 0.46). Infection with helminths was also less likely for individuals infected with giardia (HR: 0.71). Finally, treatment with mebendazole reduced subsequent hookworm infections, but resulted in a marginal increase in the odds of G. lamblia infection. Our results provide evidence for an antagonistic relationship between helminths and giardia, and suggest that co-infection should be considered in disease transmission models and treatment decisions. PMID:23986108

  20. How does selfing affect the dynamics of selfish transposable elements?

    PubMed Central

    2012-01-01

    Background Many theoretical models predicting the dynamics of transposable elements (TEs) in genomes, populations, and species have already been proposed. However, most of them only focus on populations of sexual diploid individuals, and TE dynamics in populations partly composed by autogamous individuals remains poorly investigated. To estimate the impact of selfing on TE dynamics, the short- and long-term evolution of TEs was simulated in outcrossing populations with various proportions of selfing individuals. Results Selfing has a deep impact on TE dynamics: the higher the selfing rate, the lower the probability of invasion. Already known non-equilibrium dynamics (complete loss, domestication, cyclical invasion of TEs) can all be described whatever the mating system. However, their pattern and their respective frequencies greatly depend on the selfing rate. For instance, in cyclical dynamics resulting from interactions between autonomous and non-autonomous copies, cycles are faster when the selfing rate increases. Interestingly, an abrupt change in the mating system from sexuality to complete asexuality leads to the loss of all the elements over a few hundred generations. In general, for intermediate selfing rates, the transposition activity remains maintained. Conclusions Our theoretical results evidence that a clear and systematic contrast in TE content according to the mating system is expected, with a smooth transition for intermediate selfing rates. Several parameters impact the TE copy number, and all dynamics described in allogamous populations can be also observed in partly autogamous species. This study thus provides new insights to understand the complex signal from empirical comparison of closely related species with different mating systems. PMID:22394388

  1. Effects of adaptive protective behavior on the dynamics of sexually transmitted infections.

    PubMed

    Hayashi, Michael A L; Eisenberg, Marisa C

    2016-01-01

    Sexually transmitted infections (STIs) continue to present a complex and costly challenge to public health programs. The preferences and social dynamics of a population can have a large impact on the course of an outbreak as well as the effectiveness of interventions intended to influence individual behavior. In addition, individuals may alter their sexual behavior in response to the presence of STIs, creating a feedback loop between transmission and behavior. We investigate the consequences of modeling the interaction between STI transmission and prophylactic use with a model that links a Susceptible-Infectious-Susceptible (SIS) system to evolutionary game dynamics that determine the effective contact rate. The combined model framework allows us to address protective behavior by both infected and susceptible individuals. Feedback between behavioral adaptation and prevalence creates a wide range of dynamic behaviors in the combined model, including damped and sustained oscillations as well as bistability, depending on the behavioral parameters and disease growth rate. We found that disease extinction is possible for multiple regions where R0>1, due to behavior adaptation driving the epidemic downward, although conversely endemic prevalence for arbitrarily low R0 is also possible if contact rates are sufficiently high. We also tested how model misspecification might affect disease forecasting and estimation of the model parameters and R0. We found that alternative models that neglect the behavioral feedback or only consider behavior adaptation by susceptible individuals can potentially yield misleading parameter estimates or omit significant features of the disease trajectory. PMID:26362102

  2. How vegetation patterning affects sediment dynamics in complex landscapes

    NASA Astrophysics Data System (ADS)

    Baartman, Jantiene; Temme, Arnaud; Saco, Patricia

    2016-04-01

    Semi-arid ecosystems are often spatially self-organized in typical patterns of vegetation bands with high plant cover interspersed with bare soil areas, also known as 'tigerbush'. Tigerbush dynamics have been studied using model simulations on flat synthetic landscapes, although in some cases straight slopes were used. The feedbacks between vegetation and more realistic and complex landscapes have not been studied yet, even though these landscapes are much more prevalent. Hence, our objective was to determine the effect of landform variation on vegetation patterning and sediment dynamics. We linked two existing models that simulate (a) plant growth, death and dispersal of vegetation, and (b) erosion and sedimentation. The model was calibrated on a straight planar hillslope and then applied to (i) a set of synthetic but more complex topographies and (ii) three real-world landscapes. Furthermore, sediment dynamics were evaluated by comparing simulated sediment output with and without vegetation dynamics. Results show banded vegetation patterning on all synthetic topographies, always perpendicular to the slope gradient. For real topographies, banded vegetation was simulated in the relatively flat, rolling landscape and in the dissected landscape when slopes were gentle. In the steep dissected landscape and the alluvial fan, vegetation was simulated to grow in local depressions where moisture is present whereas hilltops were bare. Including vegetation dynamics resulted in significantly less simulated erosion and relatively more deposition compared to simulations with uniformly distributed vegetation.

  3. On the dynamics of SEIRS epidemic model with transport-related infection.

    PubMed

    Denphedtnong, Adisak; Chinviriyasit, Settapat; Chinviriyasit, Wirawan

    2013-10-01

    Transportation amongst cities is found as one of the main factors which affect the outbreak of diseases. To understand the effect of transport-related infection on disease spread, an SEIRS (Susceptible, Exposed, Infectious, Recovered) epidemic model for two cities is formulated and analyzed. The epidemiological threshold, known as the basic reproduction number, of the model is derived. If the basic reproduction number is below unity, the disease-free equilibrium is locally asymptotically stable. Thus, the disease can be eradicated from the community. There exists an endemic equilibrium which is locally asymptotically stable if the reproduction number is larger than unity. This means that the disease will persist within the community. The results show that transportation among regions will change the disease dynamics and break infection out even if infectious diseases will go to extinction in each isolated region without transport-related infection. In addition, the result shows that transport-related infection intensifies the disease spread if infectious diseases break out to cause an endemic situation in each region, in the sense of that both the absolute and relative size of patients increase. Further, the formulated model is applied to the real data of SARS outbreak in 2003 to study the transmission of disease during the movement between two regions. The results show that the transport-related infection is effected to the number of infected individuals and the duration of outbreak in such the way that the disease becomes more endemic due to the movement between two cities. This study can be helpful in providing the information to public health authorities and policy maker to reduce spreading disease when its occurs.

  4. Live cell imaging of phosphoinositide dynamics during Legionella infection.

    PubMed

    Weber, Stephen; Hilbi, Hubert

    2014-01-01

    The "accidental" pathogen Legionella pneumophila replicates intracellularly in a distinct compartment, the Legionella-containing vacuole (LCV). To form this specific pathogen vacuole, the bacteria translocate via the Icm/Dot type IV secretion system approximately 300 different effector proteins into the host cell. Several of these secreted effectors anchor to the cytoplasmic face of the LCV membrane by binding to phosphoinositide (PI) lipids. L. pneumophila thus largely controls the localization of secreted bacterial effectors and the recruitment of host factors to the LCV through the modulation of the vacuole membrane PI pattern. The LCV PI pattern and its dynamics can be studied in real-time using fluorescently labeled protein probes stably produced by the soil amoeba Dictyostelium discoideum. In this chapter, we describe a protocol to (1) construct and handle amoeba model systems as a tool for observing PIs in live cell imaging, (2) capture rapid changes in membrane PI patterning during uptake events, and (3) observe the dynamics of LCV PIs over the course of a Legionella infection.

  5. Nonlinear Dynamics, Noise and Cooperative Behavior in Affective Disorders

    NASA Astrophysics Data System (ADS)

    Huber, Martin

    2001-03-01

    Mood disorders tend to be recurrent and progressive and illness patterns typically evolve from isolated episodes at the beginning to more rapid, rhythmic and finally irregular "chaotic" mood patterns. This chararacteristic timecourse prompted the consideration of nonlinear dynamics as a way to describe and analyze course and disease states of mood disorders. Indeed, some evidences now exist indicating that low-dimensional dynamics underly the illness progression. To gain an understanding of prinicple mechanisms that might underly the course and disease patterns of mood disorders, we developed a phenomenological mathematical model for the disease course. In doing so, we made use of a neuronal analogy that exists between disease patterns and neuronal spike patterns and which is commonly referred to as the kindling model of mood disorders (Post, Am J of Psychiatry 1992,149:999-1010; Huber, Braun, Krieg, Biol Psychiatry 1999,46:256-262; Huber, Braun, Krieg, Biol Psychiatry 2000,47:634-642). Using a computational implementation of this approach we investigated the possible relevance of nonlinear dynamics for the disease course, the role of cooperative interactions between nonlinear and noisy dynamics as well as the effect of sensitization mechanisms between disease episodes and disease system. Our simulations show that a low-dimensional model can phenomenologically map the timecourse of mood disorders. From a functional perspective, the model indicates an important role for stochastic fluctuations which can amplify subthreshold states into disease states and can induce transitions to irregular rapidly changing disease patterns. Interesting dynamics are observed with respect to deterministically defined disease states and their dependence on noise intensity. Finally, our simulations show how sensitization effects quite naturally lead to a disease course which ends in irregular fluctuating disease patterns as observed in clinical data. Our findings indicate the usefulness

  6. Riding the tide of emotions with mindfulness: Mindfulness, affect dynamics, and the mediating role of coping.

    PubMed

    Keng, Shian-Ling; Tong, Eddie M W

    2016-08-01

    Little research has examined ways in which mindfulness is associated with affect dynamics, referring to patterns of affect fluctuations in daily life. Using ecological momentary assessment (EMA), the present study examined the associations between trait mindfulness and several types of affect dynamics, namely affect variability, affect inertia, affect switch, and affect instability. Three hundred ninety undergraduate students from Singapore reported their current emotions and coping styles up to 19 times per day across 2 days. Results showed that trait mindfulness correlated negatively with variability, instability, and inertia of negative affect and positively with negative-to-positive affect switch. These relationships were independent of openness, habitual reappraisal, habitual suppression, depression, and self-esteem. Importantly, lower maladaptive coping was found to mediate these relationships. The study suggests that trait mindfulness independently promotes adaptive patterns of affective experiences in daily life by inhibiting maladaptive coping styles. (PsycINFO Database Record

  7. Bottom-up regulation of malaria population dynamics in mice co-infected with lung-migratory nematodes.

    PubMed

    Griffiths, Emily C; Fairlie-Clarke, Karen; Allen, Judith E; Metcalf, C Jessica E; Graham, Andrea L

    2015-12-01

    When and how populations are regulated by bottom up vs. top down processes, and how those processes are affected by co-occurring species, are poorly characterised across much of ecology. We are especially interested in the community ecology of parasites that must share a host. Here, we quantify how resources and immunity affect parasite propagation in experiments in near-replicate 'mesocosms'' - i.e. mice infected with malaria (Plasmodium chabaudi) and nematodes (Nippostrongylus brasiliensis). Nematodes suppressed immune responses against malaria, and yet malaria populations were smaller in co-infected hosts. Further analyses of within-host epidemiology revealed that nematode co-infection altered malaria propagation by suppressing target cell availability. This is the first demonstration that bottom-up resource regulation may have earlier and stronger effects than top-down immune mechanisms on within-host community dynamics. Our findings demonstrate the potential power of experimental ecology to disentangle mechanisms of population regulation in complex communities. PMID:26477454

  8. A signaling protease required for melanization in Drosophila affects resistance and tolerance of infections.

    PubMed

    Ayres, Janelle S; Schneider, David S

    2008-12-01

    Organisms evolve two routes to surviving infections-they can resist pathogen growth (resistance) and they can endure the pathogenesis of infection (tolerance). The sum of these two properties together defines the defensive capabilities of the host. Typically, studies of animal defenses focus on either understanding resistance or, to a lesser extent, tolerance mechanisms, thus providing little understanding of the relationship between these two mechanisms. We suggest there are nine possible pairwise permutations of these traits, assuming they can increase, decrease, or remain unchanged in an independent manner. Here we show that by making a single mutation in the gene encoding a protease, CG3066, active in the melanization cascade in Drosophila melanogaster, we observe the full spectrum of changes; these mutant flies show increases and decreases in their resistance and tolerance properties when challenged with a variety of pathogens. This result implicates melanization in fighting microbial infections and shows that an immune response can affect both resistance and tolerance to infections in microbe-dependent ways. The fly is often described as having an unsophisticated and stereotypical immune response where single mutations cause simple binary changes in immunity. We report a level of complexity in the fly's immune response that has strong ecological implications. We suggest that immune responses are highly tuned by evolution, since selection for defenses that alter resistance against one pathogen may change both resistance and tolerance to other pathogens.

  9. Clonal expansion during Staphylococcus aureus infection dynamics reveals the effect of antibiotic intervention.

    PubMed

    McVicker, Gareth; Prajsnar, Tomasz K; Williams, Alexander; Wagner, Nelly L; Boots, Michael; Renshaw, Stephen A; Foster, Simon J

    2014-02-01

    To slow the inexorable rise of antibiotic resistance we must understand how drugs impact on pathogenesis and influence the selection of resistant clones. Staphylococcus aureus is an important human pathogen with populations of antibiotic-resistant bacteria in hospitals and the community. Host phagocytes play a crucial role in controlling S. aureus infection, which can lead to a population "bottleneck" whereby clonal expansion of a small fraction of the initial inoculum founds a systemic infection. Such population dynamics may have important consequences on the effect of antibiotic intervention. Low doses of antibiotics have been shown to affect in vitro growth and the generation of resistant mutants over the long term, however whether this has any in vivo relevance is unknown. In this work, the population dynamics of S. aureus pathogenesis were studied in vivo using antibiotic-resistant strains constructed in an isogenic background, coupled with systemic models of infection in both the mouse and zebrafish embryo. Murine experiments revealed unexpected and complex bacterial population kinetics arising from clonal expansion during infection in particular organs. We subsequently elucidated the effect of antibiotic intervention within the host using mixed inocula of resistant and sensitive bacteria. Sub-curative tetracycline doses support the preferential expansion of resistant microorganisms, importantly unrelated to effects on growth rate or de novo resistance acquisition. This novel phenomenon is generic, occurring with methicillin-resistant S. aureus (MRSA) in the presence of β-lactams and with the unrelated human pathogen Pseudomonas aeruginosa. The selection of resistant clones at low antibiotic levels can result in a rapid increase in their prevalence under conditions that would previously not be thought to favor them. Our results have key implications for the design of effective treatment regimes to limit the spread of antimicrobial resistance, where

  10. Clonal expansion during Staphylococcus aureus infection dynamics reveals the effect of antibiotic intervention.

    PubMed

    McVicker, Gareth; Prajsnar, Tomasz K; Williams, Alexander; Wagner, Nelly L; Boots, Michael; Renshaw, Stephen A; Foster, Simon J

    2014-02-01

    To slow the inexorable rise of antibiotic resistance we must understand how drugs impact on pathogenesis and influence the selection of resistant clones. Staphylococcus aureus is an important human pathogen with populations of antibiotic-resistant bacteria in hospitals and the community. Host phagocytes play a crucial role in controlling S. aureus infection, which can lead to a population "bottleneck" whereby clonal expansion of a small fraction of the initial inoculum founds a systemic infection. Such population dynamics may have important consequences on the effect of antibiotic intervention. Low doses of antibiotics have been shown to affect in vitro growth and the generation of resistant mutants over the long term, however whether this has any in vivo relevance is unknown. In this work, the population dynamics of S. aureus pathogenesis were studied in vivo using antibiotic-resistant strains constructed in an isogenic background, coupled with systemic models of infection in both the mouse and zebrafish embryo. Murine experiments revealed unexpected and complex bacterial population kinetics arising from clonal expansion during infection in particular organs. We subsequently elucidated the effect of antibiotic intervention within the host using mixed inocula of resistant and sensitive bacteria. Sub-curative tetracycline doses support the preferential expansion of resistant microorganisms, importantly unrelated to effects on growth rate or de novo resistance acquisition. This novel phenomenon is generic, occurring with methicillin-resistant S. aureus (MRSA) in the presence of β-lactams and with the unrelated human pathogen Pseudomonas aeruginosa. The selection of resistant clones at low antibiotic levels can result in a rapid increase in their prevalence under conditions that would previously not be thought to favor them. Our results have key implications for the design of effective treatment regimes to limit the spread of antimicrobial resistance, where

  11. Prevalence of HCV and HIV infections in 2005-Earthquake-affected areas of Pakistan

    PubMed Central

    Khan, Saeed; Rai, Mohammad A; Khan, Adnan; Farooqui, Amber; Kazmi, Shahana U; Ali, Syed H

    2008-01-01

    Background On October 8, 2005, an earthquake of magnitude 7.6 hit the Northern parts of Pakistan. In the post-earthquake scenario, overcrowding, improper sewage disposal, contamination of food and drinking water, hasty surgical procedures, and unscreened blood transfusions to earthquake victims most likely promotes the spread of infections already prevalent in the area. Objective The objective of the study reported here was to determine the prevalence of Human Immunodeficiency and Hepatitis C viruses (respectively, HIV and HCV) in the earthquake-affected communities of Pakistan. The samples were analyzed 2 months and then again 11 months after the earthquake to estimate the burden of HIV and HCV in these areas, and to determine any rise in the prevalence of these viral infections as a result of the earthquake. Methods Blood samples were initially collected during December, 2005 to March 2006, from 245 inhabitants of the earthquake-affected areas. These samples were screened for HCV and HIV, using immunochromatography and Enzyme-Linked Immuno-Sorbent Assay (ELISA). Results Out of 245 samples tested, 8 (3.26%) were found positive for HCV, and 0 (0.0%) for HIV, indicating the existence of HCV infection in the earthquake-stricken areas. The same methods were used to analyze the samples collected in the second round of screening in the same area, in September, 2006 – 11 months after the earthquake. This time 290 blood samples were collected, out of which 16 (5.51%) samples were positive for HCV, and 0 for HIV. Conclusion A slightly higher prevalence of HCV was recorded 11 months after the earthquake; this increase, however, was not statistically significant. None of the study participants was found HIV-infected. PMID:18954443

  12. 9 CFR 309.7 - Livestock affected with anthrax; cleaning and disinfection of infected livestock pens and driveways.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 9 Animals and Animal Products 2 2014-01-01 2014-01-01 false Livestock affected with anthrax... INSPECTION § 309.7 Livestock affected with anthrax; cleaning and disinfection of infected livestock pens and driveways. (a) Any livestock found on ante-mortem inspection to be affected with anthrax shall be...

  13. 9 CFR 309.7 - Livestock affected with anthrax; cleaning and disinfection of infected livestock pens and driveways.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 9 Animals and Animal Products 2 2011-01-01 2011-01-01 false Livestock affected with anthrax... INSPECTION § 309.7 Livestock affected with anthrax; cleaning and disinfection of infected livestock pens and driveways. (a) Any livestock found on ante-mortem inspection to be affected with anthrax shall be...

  14. 9 CFR 309.7 - Livestock affected with anthrax; cleaning and disinfection of infected livestock pens and driveways.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 9 Animals and Animal Products 2 2012-01-01 2012-01-01 false Livestock affected with anthrax... INSPECTION § 309.7 Livestock affected with anthrax; cleaning and disinfection of infected livestock pens and driveways. (a) Any livestock found on ante-mortem inspection to be affected with anthrax shall be...

  15. 9 CFR 309.7 - Livestock affected with anthrax; cleaning and disinfection of infected livestock pens and driveways.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 9 Animals and Animal Products 2 2013-01-01 2013-01-01 false Livestock affected with anthrax... INSPECTION § 309.7 Livestock affected with anthrax; cleaning and disinfection of infected livestock pens and driveways. (a) Any livestock found on ante-mortem inspection to be affected with anthrax shall be...

  16. 9 CFR 309.7 - Livestock affected with anthrax; cleaning and disinfection of infected livestock pens and driveways.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 9 Animals and Animal Products 2 2010-01-01 2010-01-01 false Livestock affected with anthrax... INSPECTION § 309.7 Livestock affected with anthrax; cleaning and disinfection of infected livestock pens and driveways. (a) Any livestock found on ante-mortem inspection to be affected with anthrax shall be...

  17. Affective Dynamics of Leadership: An Experimental Test of Affect Control Theory

    ERIC Educational Resources Information Center

    Schroder, Tobias; Scholl, Wolfgang

    2009-01-01

    Affect Control Theory (ACT; Heise 1979, 2007) states that people control social interactions by striving to maintain culturally shared feelings about the situation. The theory is based on mathematical models of language-based impression formation. In a laboratory experiment, we tested the predictive power of a new German-language ACT model with…

  18. Effect of humoral immunity on HIV-1 dynamics with virus-to-target and infected-to-target infections

    NASA Astrophysics Data System (ADS)

    Elaiw, A. M.; Raezah, A. A.; Alofi, A. S.

    2016-08-01

    We consider an HIV-1 dynamics model by incorporating (i) two routes of infection via, respectively, binding of a virus to a receptor on the surface of a target cell to start genetic reactions (virus-to-target infection), and the direct transmission from infected cells to uninfected cells through the concept of virological synapse in vivo (infected-to-target infection); (ii) two types of distributed-time delays to describe the time between the virus or infected cell contacts an uninfected CD4+ T cell and the emission of new active viruses; (iii) humoral immune response, where the HIV-1 particles are attacked by the antibodies that are produced from the B lymphocytes. The existence and stability of all steady states are completely established by two bifurcation parameters, R 0 (the basic reproduction number) and R 1 (the viral reproduction number at the chronic-infection steady state without humoral immune response). By constructing Lyapunov functionals and using LaSalle's invariance principle, we have proven that, if R 0 ≤ 1 , then the infection-free steady state is globally asymptotically stable, if R 1 ≤ 1 < R 0 , then the chronic-infection steady state without humoral immune response is globally asymptotically stable, and if R 1 > 1 , then the chronic-infection steady state with humoral immune response is globally asymptotically stable. We have performed numerical simulations to confirm our theoretical results.

  19. Conceptualizing the dynamics of a drought affected agricultural community

    NASA Astrophysics Data System (ADS)

    Kuil, Linda; Carr, Gemma; Viglione, Alberto; Bloeschl, Guenter

    2015-04-01

    Climate and especially water availability and variability play an important role in the development of our societies. This can be seen through the vast investments that are made in reaching water security and the economic impact regions experience when the rains fail. However, the limit of available fresh water is increasingly felt as our population increases and the demand for water continues to rise. But how do we as society respond? Are periods of drought making us more resilient? The answer to this question is sought through the development of a stylized model that is built within the spirit of the Easter Island model by Brander and Taylor and aimed at capturing the essence of the dynamics of water supply and demand. By explicitly incorporating feedbacks, but keeping the framework simple, the model seeks to understand qualitative behavior of our socio-hydrological system as opposed to predicting exact pathways. The model shows that carrying capacity dynamics are a determining factor for continued growth. Future work will explore the underlying relationships further, among others, through examination of case studies.

  20. In vivo and in vitro infection dynamics of honey bee viruses

    PubMed Central

    Carrillo-Tripp, Jimena; Dolezal, Adam G.; Goblirsch, Michael J.; Miller, W. Allen; Toth, Amy L.; Bonning, Bryony C.

    2016-01-01

    The honey bee (Apis mellifera) is commonly infected by multiple viruses. We developed an experimental system for the study of such mixed viral infections in newly emerged honey bees and in the cell line AmE-711, derived from honey bee embryos. When inoculating a mixture of iflavirids [sacbrood bee virus (SBV), deformed wing virus (DWV)] and dicistrovirids [Israeli acute paralysis virus (IAPV), black queen cell virus (BQCV)] in both live bee and cell culture assays, IAPV replicated to higher levels than other viruses despite the fact that SBV was the major component of the inoculum mixture. When a different virus mix composed mainly of the dicistrovirid Kashmir bee virus (KBV) was tested in cell culture, the outcome was a rapid increase in KBV but not IAPV. We also sequenced the complete genome of an isolate of DWV that covertly infects the AmE-711 cell line, and found that this virus does not prevent IAPV and KBV from accumulating to high levels and causing cytopathic effects. These results indicate that different mechanisms of virus-host interaction affect virus dynamics, including complex virus-virus interactions, superinfections, specific virus saturation limits in cells and virus specialization for different cell types. PMID:26923109

  1. Dynamics of hantavirus infection in Peromyscus leucopus of central Pennsylvania.

    PubMed

    Luong, Lien T; Vigliotti, Beth A; Campbell, Shelley; Comer, James A; Mills, James N; Hudson, Peter J

    2011-11-01

    Hantaviruses are distributed throughout the United States and are the etiologic agents for hantavirus pulmonary syndrome and hemorrhagic fever with renal syndrome. Hantavirus genotypes and epidemiologic patterns vary spatially across the United States. While several longitudinal studies have been performed in the western United States, little is known about the virus in the eastern United States. We undertook a longitudinal study of hantaviruses in the primary rodent reservoir host in central Pennsylvania, Peromyscus leucopus. Prevalence of hantavirus antibodies varied both by year and site, but was not correlated with host abundance. Males were significantly more likely to have antibodies to a hantavirus than females, and both antibody sero-conversion and antibody prevalence increased with mass class (indicator for age). Our findings suggest that one or more hantaviruses are present and circulating among P. leucopus of central Pennsylvania, and understanding the dynamics in this region could help prevent zoonotic transmission to humans. Our aim was to describe the differences in epizootiology of hantavirus infection in rodents from various geographical locations to enable improved analysis of the risk of rodent-to-human transmission and obtain insights that may indicate improved means of disease intervention. PMID:21756028

  2. Dynamics of hantavirus infection in Peromyscus leucopus of central Pennsylvania.

    PubMed

    Luong, Lien T; Vigliotti, Beth A; Campbell, Shelley; Comer, James A; Mills, James N; Hudson, Peter J

    2011-11-01

    Hantaviruses are distributed throughout the United States and are the etiologic agents for hantavirus pulmonary syndrome and hemorrhagic fever with renal syndrome. Hantavirus genotypes and epidemiologic patterns vary spatially across the United States. While several longitudinal studies have been performed in the western United States, little is known about the virus in the eastern United States. We undertook a longitudinal study of hantaviruses in the primary rodent reservoir host in central Pennsylvania, Peromyscus leucopus. Prevalence of hantavirus antibodies varied both by year and site, but was not correlated with host abundance. Males were significantly more likely to have antibodies to a hantavirus than females, and both antibody sero-conversion and antibody prevalence increased with mass class (indicator for age). Our findings suggest that one or more hantaviruses are present and circulating among P. leucopus of central Pennsylvania, and understanding the dynamics in this region could help prevent zoonotic transmission to humans. Our aim was to describe the differences in epizootiology of hantavirus infection in rodents from various geographical locations to enable improved analysis of the risk of rodent-to-human transmission and obtain insights that may indicate improved means of disease intervention.

  3. Hendra virus infection dynamics in Australian fruit bats.

    PubMed

    Field, Hume; de Jong, Carol; Melville, Deb; Smith, Craig; Smith, Ina; Broos, Alice; Kung, Yu Hsin Nina; McLaughlin, Amanda; Zeddeman, Anne

    2011-01-01

    Hendra virus is a recently emerged zoonotic agent in Australia. Since first described in 1994, the virus has spilled from its wildlife reservoir (pteropid fruit bats, or 'flying foxes') on multiple occasions causing equine and human fatalities. We undertook a three-year longitudinal study to detect virus in the urine of free-living flying foxes (a putative route of excretion) to investigate Hendra virus infection dynamics. Pooled urine samples collected off plastic sheets placed beneath roosting flying foxes were screened for Hendra virus genome by quantitative RT-PCR, using a set of primers and probe derived from the matrix protein gene. A total of 1672 pooled urine samples from 67 sampling events was collected and tested between 1 July 2008 and 30 June 2011, with 25% of sampling events and 2.5% of urine samples yielding detections. The proportion of positive samples was statistically associated with year and location. The findings indicate that Hendra virus excretion occurs periodically rather than continuously, and in geographically disparate flying fox populations in the state of Queensland. The lack of any detection in the Northern Territory suggests prevalence may vary across the range of flying foxes in Australia. Finally, our findings suggest that flying foxes can excrete virus at any time of year, and that the apparent seasonal clustering of Hendra virus incidents in horses and associated humans (70% have occurred June to October) reflects factors other than the presence of virus. Identification of these factors will strengthen risk minimization strategies for horses and ultimately humans.

  4. Dynamics of Hantavirus Infection in Peromyscus leucopus of Central Pennsylvania

    PubMed Central

    Vigliotti, Beth A.; Campbell, Shelley; Comer, James A.; Mills, James N.; Hudson, Peter J.

    2011-01-01

    Abstract Hantaviruses are distributed throughout the United States and are the etiologic agents for hantavirus pulmonary syndrome and hemorrhagic fever with renal syndrome. Hantavirus genotypes and epidemiologic patterns vary spatially across the United States. While several longitudinal studies have been performed in the western United States, little is known about the virus in the eastern United States. We undertook a longitudinal study of hantaviruses in the primary rodent reservoir host in central Pennsylvania, Peromyscus leucopus. Prevalence of hantavirus antibodies varied both by year and site, but was not correlated with host abundance. Males were significantly more likely to have antibodies to a hantavirus than females, and both antibody sero-conversion and antibody prevalence increased with mass class (indicator for age). Our findings suggest that one or more hantaviruses are present and circulating among P. leucopus of central Pennsylvania, and understanding the dynamics in this region could help prevent zoonotic transmission to humans. Our aim was to describe the differences in epizootiology of hantavirus infection in rodents from various geographical locations to enable improved analysis of the risk of rodent-to-human transmission and obtain insights that may indicate improved means of disease intervention. PMID:21756028

  5. Enterovirus infection of human islets of Langerhans affects β-cell function resulting in disintegrated islets, decreased glucose stimulated insulin secretion and loss of Golgi structure

    PubMed Central

    Hodik, M; Skog, O; Lukinius, A; Isaza-Correa, J M; Kuipers, J; Giepmans, B N G; Frisk, G

    2016-01-01

    Aims/hypothesis In type 1 diabetes (T1D), most insulin-producing β cells are destroyed, but the trigger is unknown. One of the possible triggers is a virus infection and the aim of this study was to test if enterovirus infection affects glucose stimulated insulin secretion and the effect of virus replication on cellular macromolecules and organelles involved in insulin secretion. Methods Isolated human islets were infected with different strains of coxsackievirus B (CVB) virus and the glucose-stimulated insulin release (GSIS) was measured in a dynamic perifusion system. Classical morphological electron microscopy, large-scale electron microscopy, so-called nanotomy, and immunohistochemistry were used to study to what extent virus-infected β cells contained insulin, and real-time PCR was used to analyze virus induced changes of islet specific genes. Results In islets infected with CVB, GSIS was reduced in correlation with the degree of virus-induced islet disintegration. The expression of the gene encoding insulin was decreased in infected islets, whereas the expression of glucagon was not affected. Also, in islets that were somewhat disintegrated, there were uninfected β cells. Ultrastructural analysis revealed that virus particles and virus replication complexes were only present in β cells. There was a significant number of insulin granules remaining in the virus-infected β cells, despite decreased expression of insulin mRNA. In addition, no typical Golgi apparatus was detected in these cells. Exposure of islets to synthetic dsRNA potentiated glucose-stimulated insulin secretion. Conclusions/interpretation Glucose-stimulated insulin secretion; organelles involved in insulin secretion and gene expression were all affected by CVB replication in β cells. PMID:27547409

  6. Dynamic touch is affected in children with cerebral palsy.

    PubMed

    Ocarino, Juliana M; Fonseca, Sergio T; Silva, Paula L P; Gonçalves, Gabriela G P; Souza, Thales R; Mancini, Marisa C

    2014-02-01

    Children with developmental disorders such as cerebral palsy have limited opportunities for effortful interactions with objects and tools. The goal of the study was to investigate whether children with cerebral palsy have deficits in their ability to perceive object length by dynamic touch when compared to typically developing children. Fourteen children with typical development and 12 children with cerebral palsy were asked to report the length of hand-held rods after wielding them out of sight. Multilevel regression models indicated that I1 (maximum principal moment of inertia) was a significant predictor of perceived length - LP (p<.0001). The effect of I1 on LP was significantly different among children (p=.001) and the presence of cerebral palsy (group factor) partially explained such variance (p=.002). In addition, accuracy and reliability of the length judgments made by children with cerebral palsy were significantly lower than the typically developing children (p<.05). Theoretical and clinical implications of these results were identified and discussed.

  7. Propagation dynamics of an epidemic model with infective media connecting two separated networks of populations

    NASA Astrophysics Data System (ADS)

    Zhu, Guanghu; Chen, Guanrong; Zhang, Haifeng; Fu, Xinchu

    2015-01-01

    Based on the fact that most human pathogens originate from animals, this paper attempts to illustrate the propagation dynamics of some zoonotic infections, which spread in two separated networks of populations (human network I and animal network II) and cross-species (vectors, or infective media). An epidemic time-evolution model is proposed via mean-field approximation and its global dynamics are investigated. It is found that the basic reproduction number in terms of epidemiological parameters and the network structure is the threshold condition determining the propagation dynamics. Further, the influences of various infection rates and contact patterns are verified. Numerical results show that the heterogeneity in connection patterns and inner infection in network I can easily trigger endemic dynamics, but when a pathogen, such as H7N9, has weak infectivity in humans, the effects of animal-animal interactions and the contacts with vectors tend to induce endemic states and enhance the prevalence in all the populations.

  8. High-Density Lipoprotein Binds to Mycobacterium avium and Affects the Infection of THP-1 Macrophages

    PubMed Central

    Ichimura, Naoya; Sato, Megumi; Yoshimoto, Akira; Yano, Kouji; Ohkawa, Ryunosuke; Kasama, Takeshi

    2016-01-01

    High-density lipoprotein (HDL) is involved in innate immunity toward various infectious diseases. Concerning bacteria, HDL is known to bind to lipopolysaccharide (LPS) and to neutralize its physiological activity. On the other hand, cholesterol is known to play an important role in mycobacterial entry into host cells and in survival in the intracellular environment. However, the pathogenicity of Mycobacterium avium (M. avium) infection, which tends to increase worldwide, remains poorly studied. Here we report that HDL indicated a stronger interaction with M. avium than that with other Gram-negative bacteria containing abundant LPS. A binding of apolipoprotein (apo) A-I, the main protein component of HDL, with a specific lipid of M. avium might participate in this interaction. HDL did not have a direct bactericidal activity toward M. avium but attenuated the engulfment of M. avium by THP-1 macrophages. HDL also did not affect bacterial killing after ingestion of live M. avium by THP-1 macrophage. Furthermore, HDL strongly promoted the formation of lipid droplets in M. avium-infected THP-1 macrophages. These observations provide new insights into the relationship between M. avium infection and host lipoproteins, especially HDL. Thus, HDL may help M. avium to escape from host innate immunity. PMID:27516907

  9. Effects of a disease affecting a predator on the dynamics of a predator-prey system.

    PubMed

    Auger, Pierre; McHich, Rachid; Chowdhury, Tanmay; Sallet, Gauthier; Tchuente, Maurice; Chattopadhyay, Joydev

    2009-06-01

    We study the effects of a disease affecting a predator on the dynamics of a predator-prey system. We couple an SIRS model applied to the predator population, to a Lotka-Volterra model. The SIRS model describes the spread of the disease in a predator population subdivided into susceptible, infected and removed individuals. The Lotka-Volterra model describes the predator-prey interactions. We consider two time scales, a fast one for the disease and a comparatively slow one for predator-prey interactions and for predator mortality. We use the classical "aggregation method" in order to obtain a reduced equivalent model. We show that there are two possible asymptotic behaviors: either the predator population dies out and the prey tends to its carrying capacity, or the predator and prey coexist. In this latter case, the predator population tends either to a "disease-free" or to a "disease-endemic" state. Moreover, the total predator density in the disease-endemic state is greater than the predator density in the "disease-free" equilibrium (DFE).

  10. Factors affecting the anthelmintic efficacy of papaya latex in vivo: host sex and intensity of infection.

    PubMed

    Luoga, Wenceslaus; Mansur, Fadlul; Lowe, Ann; Duce, Ian R; Buttle, David J; Behnke, Jerzy M

    2015-07-01

    The development of plant-derived cysteine proteinases, such as those in papaya latex, as novel anthelmintics requires that the variables affecting efficacy be fully evaluated. Here, we conducted two experiments, the first to test for any effect of host sex and the second to determine whether the intensity of the worm burden carried by mice would influence efficacy. In both experiments, we used the standard C3H mouse reference strain in which papaya latex supernatant (PLS) consistently shows >80 % reduction in Heligmosomoides bakeri worm burdens, but to broaden the perspective, we also included for comparison mice of other strains that are known to respond more poorly to treatment with papaya latex. Our results confirmed that there is a strong genetic influence affecting efficacy of PLS in removing adult worm burdens. However, there was no effect of host sex on efficacy (C3H and NIH) and no effect of infection intensity (C3H and BALB/c). These results offer optimism that plant-derived cysteine proteinases (CPs), such as these from papaya latex, can function as effective anthelmintics, with neither host sex nor infection intensity presenting further hurdles to impede their development for future medicinal and veterinary usage.

  11. Herbal drug quality and phytochemical composition of Hypericum perforatum L. affected by ash yellows phytoplasma infection.

    PubMed

    Bruni, Renato; Pellati, Federica; Bellardi, Maria Grazia; Benvenuti, Stefania; Paltrinieri, Samanta; Bertaccini, Assunta; Bianchi, Alberto

    2005-02-23

    Qualitative/quantitative phytochemical variations were observed in dried flowering tops of cultivated Hypericum perforatum L. cv. Zorzi infected by phytoplasmas of the "ash yellows" class, identified by direct and nested polymerase chain reaction (PCR); this is the first report of ribosomial group 16SrVII phytoplasmas in St. John's Wort. Methanolic extracts of healthy and infected plants were separated by reversed phase high-performance liquid chromatography to quantify naphthodianthrones and flavonoids, while essential oils were analyzed by means of gas chromatography (GC)-GC/MS. The affected plants exhibited decreased amounts of rutin (1.96 +/- 0.23 vs 4.96 +/- 0.02 mg/g), hyperoside (2.38 +/- 0.21 vs 3.04 +/- 0.05 mg/g), isoquercitrin (1.47 +/- 0.04 vs 3.50 +/- 0.08 mg/g), amentoflavone (0.12 +/- 0.01 vs 0.39 +/- 0.02 mg/g), and pseudohypericin (1.41 +/- 0.23 vs 2.29 +/- 0.07 mg/g), whereas the chlorogenic acid content was doubled (1.56 +/- 0.11 vs 0.77 +/- 0.02 mg/g). Hypericin, quercitrin, and quercetin contents were not severely affected. The essential oil yield was drastically reduced in infected material (0.11 vs 0.75% in healthy material) and revealed an increased abundance of sesquiterpenes (beta-caryophyllene, delta-elemene, and germacrene D, in particular) and a matching decrease in monoterpene hydrocarbons and aliphatics. The consequences that the phytopathological condition of cultivated H. perforatum plants has on the commercial quality, market value, and therapeutic efficacy are outlined. PMID:15713006

  12. Reheating dynamics affects non-perturbative decay of spectator fields

    SciTech Connect

    Enqvist, Kari; Lerner, Rose N.; Rusak, Stanislav E-mail: rose.lerner@helsinki.fi

    2013-11-01

    The behaviour of oscillating scalar spectator fields after inflation depends on the thermal background produced by inflaton decay. Resonant decay of the spectator is often blocked by large induced thermal masses. We account for the finite decay width of the inflaton and the protracted build-up of the thermal bath to determine the early evolution of a homogeneous spectator field σ coupled to the Higgs Boson Φ through the term g{sup 2}σ{sup 2}Φ{sup 2}, the only renormalisable coupling of a new scalar to the Standard Model. We find that for very large higgs-spectator coupling g∼>10{sup −3}, the resonance is not always blocked as was previously suggested. As a consequence, the oscillating spectator can decay quickly. For other parameter values, we find that although qualitative features of the thermal blocking still hold, the dynamics are altered compared to the instant decay case. These findings are important for curvaton models, where the oscillating field must be relatively long lived in order to produce the curvature perturbation. They are also relevant for other spectator fields, which must decay sufficiently early to avoid spoiling the predictions of baryogenesis and nucleosynthesis.

  13. Mathematical Modeling of the Dynamics of Salmonella Cerro Infection in a US Dairy Herd

    NASA Astrophysics Data System (ADS)

    Chapagain, Prem; van Kessel, Jo Ann; Karns, Jeffrey; Wolfgang, David; Schukken, Ynte; Grohn, Yrjo

    2006-03-01

    Salmonellosis has been one of the major causes of human foodborne illness in the US. The high prevalence of infections makes transmission dynamics of Salmonella in a farm environment of interest both from animal and human health perspectives. Mathematical modeling approaches are increasingly being applied to understand the dynamics of various infectious diseases in dairy herds. Here, we describe the transmission dynamics of Salmonella infection in a dairy herd with a set of non-linear differential equations. Although the infection dynamics of different serotypes of Salmonella in cattle are likely to be different, we find that a relatively simple SIR-type model can describe the observed dynamics of the Salmonella enterica serotype Cerro infection in the herd.

  14. Group Size and Nest Spacing Affect Buggy Creek Virus (Togaviridae: Alphavirus) Infection in Nestling House Sparrows

    PubMed Central

    O'Brien, Valerie A.; Brown, Charles R.

    2011-01-01

    The transmission of parasites and pathogens among vertebrates often depends on host population size, host species diversity, and the extent of crowding among potential hosts, but little is known about how these variables apply to most vector-borne pathogens such as the arboviruses (arthropod-borne viruses). Buggy Creek virus (BCRV; Togaviridae: Alphavirus) is an RNA arbovirus transmitted by the swallow bug (Oeciacus vicarius) to the cliff swallow (Petrochelidon pyrrhonota) and the introduced house sparrow (Passer domesticus) that has recently invaded swallow nesting colonies. The virus has little impact on cliff swallows, but house sparrows are seriously affected by BCRV. For house sparrows occupying swallow nesting colonies in western Nebraska, USA, the prevalence of BCRV in nestling sparrows increased with sparrow colony size at a site but decreased with the number of cliff swallows present. If one nestling in a nest was infected with the virus, there was a greater likelihood that one or more of its nest-mates would also be infected than nestlings chosen at random. The closer a nest was to another nest containing infected nestlings, the greater the likelihood that some of the nestlings in the focal nest would be BCRV-positive. These results illustrate that BCRV represents a cost of coloniality for a vertebrate host (the house sparrow), perhaps the first such demonstration for an arbovirus, and that virus infection is spatially clustered within nests and within colonies. The decreased incidence of BCRV in sparrows as cliff swallows at a site increased reflects the “dilution effect,” in which virus transmission is reduced when a vector switches to feeding on a less competent vertebrate host. PMID:21966539

  15. Group size and nest spacing affect Buggy Creek virus (Togaviridae: Alphavirus) infection in nestling house sparrows.

    PubMed

    O'Brien, Valerie A; Brown, Charles R

    2011-01-01

    The transmission of parasites and pathogens among vertebrates often depends on host population size, host species diversity, and the extent of crowding among potential hosts, but little is known about how these variables apply to most vector-borne pathogens such as the arboviruses (arthropod-borne viruses). Buggy Creek virus (BCRV; Togaviridae: Alphavirus) is an RNA arbovirus transmitted by the swallow bug (Oeciacus vicarius) to the cliff swallow (Petrochelidon pyrrhonota) and the introduced house sparrow (Passer domesticus) that has recently invaded swallow nesting colonies. The virus has little impact on cliff swallows, but house sparrows are seriously affected by BCRV. For house sparrows occupying swallow nesting colonies in western Nebraska, USA, the prevalence of BCRV in nestling sparrows increased with sparrow colony size at a site but decreased with the number of cliff swallows present. If one nestling in a nest was infected with the virus, there was a greater likelihood that one or more of its nest-mates would also be infected than nestlings chosen at random. The closer a nest was to another nest containing infected nestlings, the greater the likelihood that some of the nestlings in the focal nest would be BCRV-positive. These results illustrate that BCRV represents a cost of coloniality for a vertebrate host (the house sparrow), perhaps the first such demonstration for an arbovirus, and that virus infection is spatially clustered within nests and within colonies. The decreased incidence of BCRV in sparrows as cliff swallows at a site increased reflects the "dilution effect," in which virus transmission is reduced when a vector switches to feeding on a less competent vertebrate host.

  16. Acaricide treatment affects viral dynamics in Varroa destructor-infested honey bee colonies via both host physiology and mite control.

    PubMed

    Locke, Barbara; Forsgren, Eva; Fries, Ingemar; de Miranda, Joachim R

    2012-01-01

    Honey bee (Apis mellifera) colonies are declining, and a number of stressors have been identified that affect, alone or in combination, the health of honey bees. The ectoparasitic mite Varroa destructor, honey bee viruses that are often closely associated with the mite, and pesticides used to control the mite population form a complex system of stressors that may affect honey bee health in different ways. During an acaricide treatment using Apistan (plastic strips coated with tau-fluvalinate), we analyzed the infection dynamics of deformed wing virus (DWV), sacbrood virus (SBV), and black queen cell virus (BQCV) in adult bees, mite-infested pupae, their associated Varroa mites, and uninfested pupae, comparing these to similar samples from untreated control colonies. Titers of DWV increased initially with the onset of the acaricide application and then slightly decreased progressively coinciding with the removal of the Varroa mite infestation. This initial increase in DWV titers suggests a physiological effect of tau-fluvalinate on the host's susceptibility to viral infection. DWV titers in adult bees and uninfested pupae remained higher in treated colonies than in untreated colonies. The titers of SBV and BQCV did not show any direct relationship with mite infestation and showed a variety of possible effects of the acaricide treatment. The results indicate that other factors besides Varroa mite infestation may be important to the development and maintenance of damaging DWV titers in colonies. Possible biochemical explanations for the observed synergistic effects between tau-fluvalinate and virus infections are discussed.

  17. Acaricide Treatment Affects Viral Dynamics in Varroa destructor-Infested Honey Bee Colonies via both Host Physiology and Mite Control

    PubMed Central

    Forsgren, Eva; Fries, Ingemar; de Miranda, Joachim R.

    2012-01-01

    Honey bee (Apis mellifera) colonies are declining, and a number of stressors have been identified that affect, alone or in combination, the health of honey bees. The ectoparasitic mite Varroa destructor, honey bee viruses that are often closely associated with the mite, and pesticides used to control the mite population form a complex system of stressors that may affect honey bee health in different ways. During an acaricide treatment using Apistan (plastic strips coated with tau-fluvalinate), we analyzed the infection dynamics of deformed wing virus (DWV), sacbrood virus (SBV), and black queen cell virus (BQCV) in adult bees, mite-infested pupae, their associated Varroa mites, and uninfested pupae, comparing these to similar samples from untreated control colonies. Titers of DWV increased initially with the onset of the acaricide application and then slightly decreased progressively coinciding with the removal of the Varroa mite infestation. This initial increase in DWV titers suggests a physiological effect of tau-fluvalinate on the host's susceptibility to viral infection. DWV titers in adult bees and uninfested pupae remained higher in treated colonies than in untreated colonies. The titers of SBV and BQCV did not show any direct relationship with mite infestation and showed a variety of possible effects of the acaricide treatment. The results indicate that other factors besides Varroa mite infestation may be important to the development and maintenance of damaging DWV titers in colonies. Possible biochemical explanations for the observed synergistic effects between tau-fluvalinate and virus infections are discussed. PMID:22020517

  18. Hendra virus infection dynamics in Australian fruit bats.

    PubMed

    Field, Hume; de Jong, Carol; Melville, Deb; Smith, Craig; Smith, Ina; Broos, Alice; Kung, Yu Hsin Nina; McLaughlin, Amanda; Zeddeman, Anne

    2011-01-01

    Hendra virus is a recently emerged zoonotic agent in Australia. Since first described in 1994, the virus has spilled from its wildlife reservoir (pteropid fruit bats, or 'flying foxes') on multiple occasions causing equine and human fatalities. We undertook a three-year longitudinal study to detect virus in the urine of free-living flying foxes (a putative route of excretion) to investigate Hendra virus infection dynamics. Pooled urine samples collected off plastic sheets placed beneath roosting flying foxes were screened for Hendra virus genome by quantitative RT-PCR, using a set of primers and probe derived from the matrix protein gene. A total of 1672 pooled urine samples from 67 sampling events was collected and tested between 1 July 2008 and 30 June 2011, with 25% of sampling events and 2.5% of urine samples yielding detections. The proportion of positive samples was statistically associated with year and location. The findings indicate that Hendra virus excretion occurs periodically rather than continuously, and in geographically disparate flying fox populations in the state of Queensland. The lack of any detection in the Northern Territory suggests prevalence may vary across the range of flying foxes in Australia. Finally, our findings suggest that flying foxes can excrete virus at any time of year, and that the apparent seasonal clustering of Hendra virus incidents in horses and associated humans (70% have occurred June to October) reflects factors other than the presence of virus. Identification of these factors will strengthen risk minimization strategies for horses and ultimately humans. PMID:22174865

  19. Ecological and Dynamical Study of the Creative Process and Affects of Scientific Students Working in Groups

    ERIC Educational Resources Information Center

    Peilloux, Aurélien; Botella, Marion

    2016-01-01

    Although creativity has drawn the attention of researchers during the past century, collaborative processes have barely been investigated. In this article, the collective dimension of a creative process is investigated, based on a dynamic and ecological approach that includes an affective component. "Dynamic" means that the creative…

  20. A dynamical-systems approach for computing ice-affected streamflow

    USGS Publications Warehouse

    Holtschlag, David J.

    1996-01-01

    A dynamical-systems approach was developed and evaluated for computing ice-affected streamflow. The approach provides for dynamic simulation and parameter estimation of site-specific equations relating ice effects to routinely measured environmental variables. Comparison indicates that results from the dynamical-systems approach ranked higher than results from 11 analytical methods previously investigated on the basis of accuracy and feasibility criteria. Additional research will likely lead to further improvements in the approach.

  1. Nitrogen Additions Affect Root Dynamics in a Boreal Forest Ecosystem

    NASA Astrophysics Data System (ADS)

    Turner, K. M.; Treseder, K. K.

    2004-12-01

    As with many ecosystems, North American boreal forests are increasingly subjected to anthropogenic nitrogen deposition. To examine potential effects on plant growth, we created nitrogen fertilization plots in three sites along an Alaskan fire chronosequence composed of forests aged 5, 17, and 80 years. Each site had been exposed to two years of nitrogen fertilization, with four control plots and four nitrogen plots per site. General observations indicate that aboveground net primary productivity appears to be nitrogen limited in each site. We hypothesized that nitrogen fertilization would positively influence root dynamics as well, with nitrogen additions resulting in an increase in standing root biomass and length. To test our hypothesis, we used a minirhizotron camera to collect sequential images of roots in the top 10 cm of soil in both nitrogen fertilized and control plots in each site. Images were collected monthly during the growing season, with a total of five sampling times between May 2003 and May 2004. We then analyzed the images with WinRhizotron root measurement software. Nitrogen fertilization had varying effects on root biomass among the three sites, with a significant site by N interaction (P = 0.039). A decrease in root biomass was observed in the 5 and 80 year old sites, dropping from 207 g/m2 to 79 g/m2 and from 230 g/m2 to 129 g/m2 for the youngest and oldest sites, respectively. In contrast, root biomass increased from 52 g/m2 to 107 g/m2 in the 17 year old site. (Values are for the top 10 cm of soil only, and likely underestimate total root stocks.) Patterns in standing root lengths diverged from those of root biomass, with a 2.5-fold overall increase under nitrogen fertilization across all sites (P = 0.004). There were no significant differences among sites in nitrogen response. Standing root biomass and length differed from one another in their responses to nitrogen fertilization because nitrogen additions decreased specific root weight (as g

  2. Treatment of urodelans based on temperature dependent infection dynamics of Batrachochytrium salamandrivorans.

    PubMed

    Blooi, M; Martel, A; Haesebrouck, F; Vercammen, F; Bonte, D; Pasmans, F

    2015-01-01

    The recently emerged chytrid fungus Batrachochytrium salamandrivorans currently causes amphibian population declines. We hypothesized that temperature dictates infection dynamics of B. salamandrivorans, and that therefore heat treatment may be applied to clear animals from infection. We examined the impact of environmental temperature on B. salamandrivorans infection and disease dynamics in fire salamanders (Salamandra salamandra). Colonization of salamanders by B. salamandrivorans occurred at 15°C and 20°C but not at 25°C, with a significantly faster buildup of infection load and associated earlier mortality at 15°C. Exposing B. salamandrivorans infected salamanders to 25°C for 10 days resulted in complete clearance of infection and clinically cured all experimentally infected animals. This treatment protocol was validated in naturally infected wild fire salamanders. In conclusion, we show that B. salamandrivorans infection and disease dynamics are significantly dictated by environmental temperature, and that heat treatment is a viable option for clearing B. salamandrivorans infections. PMID:25623498

  3. The Dynamic Role of Personality States in Mediating the Relationship between Extraversion and Positive Affect

    PubMed Central

    Wilt, Joshua; Noftle, Erik E.; Fleeson, William; Spain, Jana S.

    2012-01-01

    Objective One of the most noteworthy and robust findings in personality psychology is the relationship between extraversion and positive affect. Existing theories have debated the origins and nature of this relationship, offering both structural/fixed and environmental/dynamic explanations. We tested the novel and straightforward dynamic hypothesis that part of the reason trait extraversion predicts trait positive affect is through an increased propensity to enact extraverted states, which in turn leads to experiencing more positive affect states. Method We report five experience sampling studies (and a meta-analysis of primary studies) conducted in natural environments and laboratory settings in which undergraduate participants (N = 241) provided ratings of trait extraversion, trait positive affect, extraversion states, and positive affect states. Results Results of primary studies and the meta analysis showed that relationships between trait extraversion and trait positive affect were partially mediated by aggregated extraversion states and aggregated positive affect states. Conclusions The results supported our dynamic hypothesis and suggested that dynamic explanations of the relationship between trait extraversion and trait positive affect are compatible with structural explanations. An important implication of these findings is that individuals might be able to increase their happiness by self-regulating their extraverted states. PMID:22092066

  4. Dynamic modulation of HSV chromatin drives initiation of infection and provides targets for epigenetic therapies

    PubMed Central

    Kristie, Thomas M.

    2015-01-01

    Upon infection, the genomes of herpesviruses undergo a striking transition from a non-nucleosomal structure to a chromatin structure. The rapid assembly and modulation of nucleosomes during the initial stage of infection results in an overlay of complex regulation that requires interactions of a plethora of chromatin modulation components. For herpes simplex virus, the initial chromatin dynamic is dependent on viral and host cell transcription factors and coactivators that mediate the balance between heterochromatic suppression of the viral genome and the euchromatin transition that allows and promotes the expression of viral immediate early genes. Strikingly similar to lytic infection, in sensory neurons this dynamic transition between heterochromatin and euchromatin governs the establishment, maintenance, and reactivation from the latent state. Chromatin dynamics in both the lytic infection and latency-reactivation cycles provides opportunities to shift the balance using small molecule epigenetic modulators to suppress viral infection, shedding, and reactivation from latency. PMID:25702087

  5. Flavor of oranges as impacted by abscission zone formation for trees affected by huanglongbing disease and Lasiodiploida infection

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Trees affected by Huanglongbing (HLB) exhibit excessive fruit drop, which is exacerbated by secondary infection of the abscission zone by the fungus Lasiodiplodia. ‘Hamlin’ orange trees, both healthy and affected by HLB, Candidatus Liberibacter asiaticus (CLas, determined by Polymerase chain reactio...

  6. Fighting while parasitized: can nematode infections affect the outcome of staged combat in beetles?

    PubMed

    Vasquez, David; Willoughby, Anna; Davis, Andrew K

    2015-01-01

    The effects of non-lethal parasites may be felt most strongly when hosts engage in intense, energy-demanding behaviors. One such behavior is fighting with conspecifics, which is common among territorial animals, including many beetle species. We examined the effects of parasites on the fighting ability of a saproxylic beetle, the horned passalus (Odontotaenius disjunctus, Family: Passalidae), which is host to a non-lethal nematode, Chondronema passali. We pitted pairs of randomly-chosen (but equally-weighted) beetles against each other in a small arena and determined the winner and aggression level of fights. Then we examined beetles for the presence, and severity of nematode infections. There was a non-significant tendency (p = 0.065) for the frequency of wins, losses and draws to differ between beetles with and without C. passali; non-parasitized individuals (n = 104) won 47% of their fights while those with the parasite (n = 88) won 34%, a 13% difference in wins. The number of nematodes in a beetle affected the outcome of fights between infected and uninfected individuals in an unexpected fashion: fighting ability was lowest in beetles with the lowest (p = 0.033), not highest (p = 0.266), nematode burdens. Within-fight aggression was highest when both beetles were uninfected and lowest when both were infected (p = 0.034). Collectively, these results suggest the nematode parasite, C. passali, is associated with a modest reduction in fighting ability in horned passalus beetles, consistent with the idea that parasitized beetles have lower energy available for fighting. This study adds to a small but growing body of evidence showing how parasites negatively influence fighting behavior in animals.

  7. Fighting while Parasitized: Can Nematode Infections Affect the Outcome of Staged Combat in Beetles?

    PubMed Central

    Vasquez, David; Willoughby, Anna; Davis, Andrew K.

    2015-01-01

    The effects of non-lethal parasites may be felt most strongly when hosts engage in intense, energy-demanding behaviors. One such behavior is fighting with conspecifics, which is common among territorial animals, including many beetle species. We examined the effects of parasites on the fighting ability of a saproxylic beetle, the horned passalus (Odontotaenius disjunctus, Family: Passalidae), which is host to a non-lethal nematode, Chondronema passali. We pitted pairs of randomly-chosen (but equally-weighted) beetles against each other in a small arena and determined the winner and aggression level of fights. Then we examined beetles for the presence, and severity of nematode infections. There was a non-significant tendency (p = 0.065) for the frequency of wins, losses and draws to differ between beetles with and without C. passali; non-parasitized individuals (n = 104) won 47% of their fights while those with the parasite (n = 88) won 34%, a 13% difference in wins. The number of nematodes in a beetle affected the outcome of fights between infected and uninfected individuals in an unexpected fashion: fighting ability was lowest in beetles with the lowest (p = 0.033), not highest (p = 0.266), nematode burdens. Within-fight aggression was highest when both beetles were uninfected and lowest when both were infected (p = 0.034). Collectively, these results suggest the nematode parasite, C. passali, is associated with a modest reduction in fighting ability in horned passalus beetles, consistent with the idea that parasitized beetles have lower energy available for fighting. This study adds to a small but growing body of evidence showing how parasites negatively influence fighting behavior in animals. PMID:25830367

  8. Parasite infection negatively affects PHA-triggered inflammation in the subterranean rodent Ctenomys talarum.

    PubMed

    Merlo, Julieta L; Cutrera, Ana P; Zenuto, Roxana R

    2016-02-01

    Magnitude and effectiveness of immune responses vary greatly between and within species. Among factors reported to determine this variation, parasitism is a critical one, although controversial effects of parasites over immunological indices have been reported. Information regarding immune strategies in species with different life histories is crucial to better understand the role of immune defenses in an ecological and evolutionary context. Here, we examine the influence of the parasite community on immune responsiveness of a solitary subterranean rodent, Ctenomys talarum. To do this, we assessed the impact of the natural parasite community and the experimental infection with Eimeria sp. on the phytohemagglutinin (PHA)-response, as well as other immune, condition, nutrition, and stress parameters. PHA-triggered inflammation was similarly impaired by Eimeria sp. infection alone or co-occurring with a number of gastrointestinal nematodes. None of the other physiological parameters studied were affected by parasitism. This indicates that parasitism is a general key factor modulating immune responsiveness of the host, and in particular for C. talarum, it could explain the great inter-individual variation previously observed in the PHA-response. Thus, our results highlight the importance of taking the parasite community into account in ecoimmunological studies, particularly when using immunological indices.

  9. Infection dynamics of Kudoa yasunagai (Myxozoa: Multivalvulida) infecting brain of cultured yellowtail Seriola quinqueradiata in Japan.

    PubMed

    Shirakashi, Sho; Morita, Akinobu; Ishimaru, Katsuya; Miyashita, Shigeru

    2012-11-01

    We monitored infection by a brain-infecting myxozoan Kudoa yasunagai in hatchery-reared juvenile yellowtail Seriola quinqueradiata at a culturing site in Japan. Infection was detected by PCR and microscopic observation once every 1 to 4 wk during 2010 and 2011. In both years, we detected first infection in mid-July by PCR. Prevalence increased rapidly after the onset of infection, peaking at 100% within 4 wk. Parasites required less than 10 d to reach the brain after invasion. Development of plasmodia and formation of cysts took 4 to 8 wk. Infection did not reach a plateau and number of cysts tended to decline over time, suggesting possible recovery from the infection. A drastic decline in infection prevalence was observed during the season of highest water temperature (>30°C) in 2010. To understand this phenomenon, we conducted a laboratory experiment to compare infection prevalence and cyst formation in fish kept at 25°C and 30°C. However, we could not detect obvious differences between the treatment groups during the 4 wk of the experiment. There was no apparent pathology associated with the infection. These results suggest that pathological effects of K. yasunagai may differ between fish species or that other factors are important in the development of infectious signs. PMID:23135139

  10. Modelling and analysis of dynamics of viral infection of cells and of interferon resistance

    NASA Astrophysics Data System (ADS)

    Getto, Ph.; Kimmel, M.; Marciniak-Czochra, A.

    2008-08-01

    Interferons are active biomolecules, which help fight viral infections by spreading from infected to uninfected cells and activate effector molecules, which confer resistance from the virus on cells. We propose a new model of dynamics of viral infection, including endocytosis, cell death, production of interferon and development of resistance. The novel element is a specific biologically justified mechanism of interferon action, which results in dynamics different from other infection models. The model reflects conditions prevailing in liquid cultures (ideal mixing), and the absence of cells or virus influx from outside. The basic model is a nonlinear system of five ordinary differential equations. For this variant, it is possible to characterise global behaviour, using a conservation law. Analytic results are supplemented by computational studies. The second variant of the model includes age-of-infection structure of infected cells, which is described by a transport-type partial differential equation for infected cells. The conclusions are: (i) If virus mortality is included, the virus becomes eventually extinct and subpopulations of uninfected and resistant cells are established. (ii) If virus mortality is not included, the dynamics may lead to extinction of uninfected cells. (iii) Switching off the interferon defense results in a decrease of the sum total of uninfected and resistant cells. (iv) Infection-age structure of infected cells may result in stabilisation or destabilisation of the system, depending on detailed assumptions. Our work seems to constitute the first comprehensive mathematical analysis of the cell-virus-interferon system based on biologically plausible hypotheses.

  11. Multilevel dynamic systems affecting introduction of HIV/STI prevention innovations among Chinese women in sex work establishments.

    PubMed

    Weeks, Margaret R; Li, Jianghong; Liao, Susu; Zhang, Qingning; Dunn, Jennifer; Wang, Yanhong; Jiang, Jingmei

    2013-10-01

    Social and public health scientists are increasingly interested in applying system dynamics theory to improve understanding and to harness the forces of change within complex, multilevel systems that affect community intervention implementation, effects, and sustainability. Building a system dynamics model based on ethnographic case study has the advantage of using empirically documented contextual factors and processes of change in a real-world and real-time setting that can then be tested in the same and other settings. System dynamics modeling offers great promise for addressing persistent problems like HIV and other sexually transmitted epidemics, particularly in complex rapidly developing countries such as China. We generated a system dynamics model of a multilevel intervention we conducted to promote female condoms for HIV/sexually transmitted infection (STI) prevention among Chinese women in sex work establishments. The model reflects factors and forces affecting the study's intervention, implementation, and effects. To build this conceptual model, we drew on our experiences and findings from this intensive, longitudinal mixed-ethnographic and quantitative four-town comparative case study (2007-2012) of the sex work establishments, the intervention conducted in them, and factors likely to explain variation in process and outcomes in the four towns. Multiple feedback loops in the sex work establishments, women's social networks, and the health organization responsible for implementing HIV/STI interventions in each town and at the town level directly or indirectly influenced the female condom intervention. We present the conceptual system dynamics model and discuss how further testing in this and other settings can inform future community interventions to reduce HIV and STIs. PMID:24084394

  12. Multilevel dynamic systems affecting introduction of HIV/STI prevention innovations among Chinese women in sex work establishments.

    PubMed

    Weeks, Margaret R; Li, Jianghong; Liao, Susu; Zhang, Qingning; Dunn, Jennifer; Wang, Yanhong; Jiang, Jingmei

    2013-10-01

    Social and public health scientists are increasingly interested in applying system dynamics theory to improve understanding and to harness the forces of change within complex, multilevel systems that affect community intervention implementation, effects, and sustainability. Building a system dynamics model based on ethnographic case study has the advantage of using empirically documented contextual factors and processes of change in a real-world and real-time setting that can then be tested in the same and other settings. System dynamics modeling offers great promise for addressing persistent problems like HIV and other sexually transmitted epidemics, particularly in complex rapidly developing countries such as China. We generated a system dynamics model of a multilevel intervention we conducted to promote female condoms for HIV/sexually transmitted infection (STI) prevention among Chinese women in sex work establishments. The model reflects factors and forces affecting the study's intervention, implementation, and effects. To build this conceptual model, we drew on our experiences and findings from this intensive, longitudinal mixed-ethnographic and quantitative four-town comparative case study (2007-2012) of the sex work establishments, the intervention conducted in them, and factors likely to explain variation in process and outcomes in the four towns. Multiple feedback loops in the sex work establishments, women's social networks, and the health organization responsible for implementing HIV/STI interventions in each town and at the town level directly or indirectly influenced the female condom intervention. We present the conceptual system dynamics model and discuss how further testing in this and other settings can inform future community interventions to reduce HIV and STIs.

  13. Dynamics of Puumala hantavirus infection in naturally infected bank voles (Clethrinomys glareolus).

    PubMed

    Bernshtein, A D; Apekina, N S; Mikhailova, T V; Myasnikov, Y A; Khlyap, L A; Korotkov, Y S; Gavrilovskaya, I N

    1999-01-01

    Specific features of hantavirus infection in bank vole (Clethrionomys glareolus) were studied in the endemic area of hemorrhagic fever with renal syndrome (HFRS) in the foothills of the Ural mountains, using long-term observations on living animals by the capture-mark-recapture (CMR) method. The results demonstrated that the infection naturally circulating in the voles is chronic (lasting for up to 15 months) and asymptomatic, with a peak of Puumala virus accumulation and release from the organism during the first month after infection. It was shown that the bank vole population includes young animals with maternal immunity, which remain resistant to the Puumala virus infection for 3-3.5 months. The infection rate in voles depended on the age and sexual maturity of animals. The greatest proportion of seropositive animals was observed among overwintered males. Seroconversion in voles was more frequent during the period of high reproductive activity.

  14. Dynamics of Puumala hantavirus infection in naturally infected bank voles (Clethrinomys glareolus).

    PubMed

    Bernshtein, A D; Apekina, N S; Mikhailova, T V; Myasnikov, Y A; Khlyap, L A; Korotkov, Y S; Gavrilovskaya, I N

    1999-01-01

    Specific features of hantavirus infection in bank vole (Clethrionomys glareolus) were studied in the endemic area of hemorrhagic fever with renal syndrome (HFRS) in the foothills of the Ural mountains, using long-term observations on living animals by the capture-mark-recapture (CMR) method. The results demonstrated that the infection naturally circulating in the voles is chronic (lasting for up to 15 months) and asymptomatic, with a peak of Puumala virus accumulation and release from the organism during the first month after infection. It was shown that the bank vole population includes young animals with maternal immunity, which remain resistant to the Puumala virus infection for 3-3.5 months. The infection rate in voles depended on the age and sexual maturity of animals. The greatest proportion of seropositive animals was observed among overwintered males. Seroconversion in voles was more frequent during the period of high reproductive activity. PMID:10664394

  15. Herbivory affects salt marsh succession dynamics by suppressing the recovery of dominant species.

    PubMed

    Daleo, Pedro; Alberti, Juan; Pascual, Jesús; Canepuccia, Alejandro; Iribarne, Oscar

    2014-05-01

    Disturbance can generate heterogeneous environments and profoundly influence plant diversity by creating patches at different successional stages. Herbivores, in turn, can govern plant succession dynamics by determining the rate of species replacement, ultimately affecting plant community structure. In a south-western Atlantic salt marsh, we experimentally evaluated the role of herbivory in the recovery following disturbance of the plant community and assessed whether herbivory affects the relative importance of sexual and clonal reproduction on these dynamics. Our results show that herbivory strongly affects salt marsh secondary succession by suppressing seedlings and limiting clonal colonization of the dominant marsh grass, allowing subordinate species to dominate disturbed patches. These results demonstrate that herbivores can have an important role in salt marsh community structure and function, and can be a key force during succession dynamics.

  16. Heterogeneous and Dynamic Prevalence of Asymptomatic Influenza Virus Infections

    PubMed Central

    Furuya-Kanamori, Luis; Cox, Mitchell; Milinovich, Gabriel J.; Magalhaes, Ricardo J. Soares; Mackay, Ian M.

    2016-01-01

    Influenza infection manifests in a wide spectrum of severity, including symptomless pathogen carriers. We conducted a systematic review and meta-analysis of 55 studies to elucidate the proportional representation of these asymptomatic infected persons. We observed extensive heterogeneity among these studies. The prevalence of asymptomatic carriage (total absence of symptoms) ranged from 5.2% to 35.5% and subclinical cases (illness that did not meet the criteria for acute respiratory or influenza-like illness) from 25.4% to 61.8%. Statistical analysis showed that the heterogeneity could not be explained by the type of influenza, the laboratory tests used to detect the virus, the year of the study, or the location of the study. Projections of infection spread and strategies for disease control require that we identify the proportional representation of these insidious spreaders early on in the emergence of new influenza subtypes or strains and track how this rate evolves over time and space. PMID:27191967

  17. Heterogeneous and Dynamic Prevalence of Asymptomatic Influenza Virus Infections.

    PubMed

    Furuya-Kanamori, Luis; Cox, Mitchell; Milinovich, Gabriel J; Magalhaes, Ricardo J Soares; Mackay, Ian M; Yakob, Laith

    2016-06-01

    Influenza infection manifests in a wide spectrum of severity, including symptomless pathogen carriers. We conducted a systematic review and meta-analysis of 55 studies to elucidate the proportional representation of these asymptomatic infected persons. We observed extensive heterogeneity among these studies. The prevalence of asymptomatic carriage (total absence of symptoms) ranged from 5.2% to 35.5% and subclinical cases (illness that did not meet the criteria for acute respiratory or influenza-like illness) from 25.4% to 61.8%. Statistical analysis showed that the heterogeneity could not be explained by the type of influenza, the laboratory tests used to detect the virus, the year of the study, or the location of the study. Projections of infection spread and strategies for disease control require that we identify the proportional representation of these insidious spreaders early on in the emergence of new influenza subtypes or strains and track how this rate evolves over time and space. PMID:27191967

  18. Health trajectories reveal the dynamic contributions of host genetic resistance and tolerance to infection outcome

    PubMed Central

    Lough, Graham; Kyriazakis, Ilias; Bergmann, Silke; Lengeling, Andreas; Doeschl-Wilson, Andrea B.

    2015-01-01

    Resistance and tolerance are two alternative strategies hosts can adopt to survive infections. Both strategies may be genetically controlled. To date, the relative contribution of resistance and tolerance to infection outcome is poorly understood. Here, we use a bioluminescent Listeria monocytogenes (Lm) infection challenge model to study the genetic determination and dynamic contributions of host resistance and tolerance to listeriosis in four genetically diverse mouse strains. Using conventional statistical analyses, we detect significant genetic variation in both resistance and tolerance, but cannot capture the time-dependent relative importance of either host strategy. We overcome these limitations through the development of novel statistical tools to analyse individual infection trajectories portraying simultaneous changes in infection severity and health. Based on these tools, early expression of resistance followed by expression of tolerance emerge as important hallmarks for surviving Lm infections. Our trajectory analysis further reveals that survivors and non-survivors follow distinct infection paths (which are also genetically determined) and provides new survival thresholds as objective endpoints in infection experiments. Future studies may use trajectories as novel traits for mapping and identifying genes that control infection dynamics and outcome. A Matlab script for user-friendly trajectory analysis is provided. PMID:26582028

  19. Form of an evolutionary tradeoff affects eco-evolutionary dynamics in a predator-prey system.

    PubMed

    Kasada, Minoru; Yamamichi, Masato; Yoshida, Takehito

    2014-11-11

    Evolution on a time scale similar to ecological dynamics has been increasingly recognized for the last three decades. Selection mediated by ecological interactions can change heritable phenotypic variation (i.e., evolution), and evolution of traits, in turn, can affect ecological interactions. Hence, ecological and evolutionary dynamics can be tightly linked and important to predict future dynamics, but our understanding of eco-evolutionary dynamics is still in its infancy and there is a significant gap between theoretical predictions and empirical tests. Empirical studies have demonstrated that the presence of genetic variation can dramatically change ecological dynamics, whereas theoretical studies predict that eco-evolutionary dynamics depend on the details of the genetic variation, such as the form of a tradeoff among genotypes, which can be more important than the presence or absence of the genetic variation. Using a predator-prey (rotifer-algal) experimental system in laboratory microcosms, we studied how different forms of a tradeoff between prey defense and growth affect eco-evolutionary dynamics. Our experimental results show for the first time to our knowledge that different forms of the tradeoff produce remarkably divergent eco-evolutionary dynamics, including near fixation, near extinction, and coexistence of algal genotypes, with quantitatively different population dynamics. A mathematical model, parameterized from completely independent experiments, explains the observed dynamics. The results suggest that knowing the details of heritable trait variation and covariation within a population is essential for understanding how evolution and ecology will interact and what form of eco-evolutionary dynamics will result. PMID:25336757

  20. Identification of Climatic Factors Affecting the Epidemiology of Human West Nile Virus Infections in Northern Greece.

    PubMed

    Stilianakis, Nikolaos I; Syrris, Vasileios; Petroliagkis, Thomas; Pärt, Peeter; Gewehr, Sandra; Kalaitzopoulou, Stella; Mourelatos, Spiros; Baka, Agoritsa; Pervanidou, Danai; Vontas, John; Hadjichristodoulou, Christos

    2016-01-01

    Climate can affect the geographic and seasonal patterns of vector-borne disease incidence such as West Nile Virus (WNV) infections. We explore the association between climatic factors and the occurrence of West Nile fever (WNF) or West Nile neuro-invasive disease (WNND) in humans in Northern Greece over the years 2010-2014. Time series over a period of 30 years (1979-2008) of climatic data of air temperature, relative humidity, soil temperature, volumetric soil water content, wind speed, and precipitation representing average climate were obtained utilising the ECMWF's (European Centre for Medium-Range Weather Forecasts) Re-Analysis (ERA-Interim) system allowing for a homogeneous set of data in time and space. We analysed data of reported human cases of WNF/WNND and Culex mosquitoes in Northern Greece. Quantitative assessment resulted in identifying associations between the above climatic variables and reported human cases of WNF/WNND. A substantial fraction of the cases was linked to the upper percentiles of the distribution of air and soil temperature for the period 1979-2008 and the lower percentiles of relative humidity and soil water content. A statistically relevant relationship between the mean weekly value climatic anomalies of wind speed (negative association), relative humidity (negative association) and air temperature (positive association) over 30 years, and reported human cases of WNF/WNND during the period 2010-2014 could be shown. A negative association between the presence of WNV infected Culex mosquitoes and wind speed could be identified. The statistically significant associations could also be confirmed for the week the WNF/WNND human cases appear and when a time lag of up to three weeks was considered. Similar statistically significant associations were identified with the weekly anomalies of the maximum and minimum values of the above climatic factors. Utilising the ERA-Interim re-analysis methodology it could be shown that besides air

  1. Identification of Climatic Factors Affecting the Epidemiology of Human West Nile Virus Infections in Northern Greece.

    PubMed

    Stilianakis, Nikolaos I; Syrris, Vasileios; Petroliagkis, Thomas; Pärt, Peeter; Gewehr, Sandra; Kalaitzopoulou, Stella; Mourelatos, Spiros; Baka, Agoritsa; Pervanidou, Danai; Vontas, John; Hadjichristodoulou, Christos

    2016-01-01

    Climate can affect the geographic and seasonal patterns of vector-borne disease incidence such as West Nile Virus (WNV) infections. We explore the association between climatic factors and the occurrence of West Nile fever (WNF) or West Nile neuro-invasive disease (WNND) in humans in Northern Greece over the years 2010-2014. Time series over a period of 30 years (1979-2008) of climatic data of air temperature, relative humidity, soil temperature, volumetric soil water content, wind speed, and precipitation representing average climate were obtained utilising the ECMWF's (European Centre for Medium-Range Weather Forecasts) Re-Analysis (ERA-Interim) system allowing for a homogeneous set of data in time and space. We analysed data of reported human cases of WNF/WNND and Culex mosquitoes in Northern Greece. Quantitative assessment resulted in identifying associations between the above climatic variables and reported human cases of WNF/WNND. A substantial fraction of the cases was linked to the upper percentiles of the distribution of air and soil temperature for the period 1979-2008 and the lower percentiles of relative humidity and soil water content. A statistically relevant relationship between the mean weekly value climatic anomalies of wind speed (negative association), relative humidity (negative association) and air temperature (positive association) over 30 years, and reported human cases of WNF/WNND during the period 2010-2014 could be shown. A negative association between the presence of WNV infected Culex mosquitoes and wind speed could be identified. The statistically significant associations could also be confirmed for the week the WNF/WNND human cases appear and when a time lag of up to three weeks was considered. Similar statistically significant associations were identified with the weekly anomalies of the maximum and minimum values of the above climatic factors. Utilising the ERA-Interim re-analysis methodology it could be shown that besides air

  2. Identification of Climatic Factors Affecting the Epidemiology of Human West Nile Virus Infections in Northern Greece

    PubMed Central

    Stilianakis, Nikolaos I.; Syrris, Vasileios; Petroliagkis, Thomas; Pärt, Peeter; Gewehr, Sandra; Kalaitzopoulou, Stella; Mourelatos, Spiros; Baka, Agoritsa; Pervanidou, Danai; Vontas, John; Hadjichristodoulou, Christos

    2016-01-01

    Climate can affect the geographic and seasonal patterns of vector-borne disease incidence such as West Nile Virus (WNV) infections. We explore the association between climatic factors and the occurrence of West Nile fever (WNF) or West Nile neuro-invasive disease (WNND) in humans in Northern Greece over the years 2010–2014. Time series over a period of 30 years (1979–2008) of climatic data of air temperature, relative humidity, soil temperature, volumetric soil water content, wind speed, and precipitation representing average climate were obtained utilising the ECMWF’s (European Centre for Medium-Range Weather Forecasts) Re-Analysis (ERA-Interim) system allowing for a homogeneous set of data in time and space. We analysed data of reported human cases of WNF/WNND and Culex mosquitoes in Northern Greece. Quantitative assessment resulted in identifying associations between the above climatic variables and reported human cases of WNF/WNND. A substantial fraction of the cases was linked to the upper percentiles of the distribution of air and soil temperature for the period 1979–2008 and the lower percentiles of relative humidity and soil water content. A statistically relevant relationship between the mean weekly value climatic anomalies of wind speed (negative association), relative humidity (negative association) and air temperature (positive association) over 30 years, and reported human cases of WNF/WNND during the period 2010–2014 could be shown. A negative association between the presence of WNV infected Culex mosquitoes and wind speed could be identified. The statistically significant associations could also be confirmed for the week the WNF/WNND human cases appear and when a time lag of up to three weeks was considered. Similar statistically significant associations were identified with the weekly anomalies of the maximum and minimum values of the above climatic factors. Utilising the ERA-Interim re-analysis methodology it could be shown that besides

  3. Effects of Aging on Influenza Virus Infection Dynamics

    PubMed Central

    Hernandez-Vargas, Esteban A.; Wilk, Esther; Canini, Laetitia; Toapanta, Franklin R.; Binder, Sebastian C.; Uvarovskii, Alexey; Ross, Ted M.; Guzmán, Carlos A.

    2014-01-01

    ABSTRACT The consequences of influenza virus infection are generally more severe in individuals over 65 years of age (the elderly). Immunosenescence enhances the susceptibility to viral infections and renders vaccination less effective. Understanding age-related changes in the immune system is crucial in order to design prophylactic and immunomodulatory strategies to reduce morbidity and mortality in the elderly. Here, we propose different mathematical models to provide a quantitative understanding of the immune strategies in the course of influenza virus infection using experimental data from young and aged mice. Simulation results suggested a central role of CD8+ T cells for adequate viral clearance kinetics in young and aged mice. Adding the removal of infected cells by natural killer cells did not improve the model fit in either young or aged animals. We separately examined the infection-resistant state of cells promoted by the cytokines alpha/beta interferon (IFN-α/β), IFN-γ, and tumor necrosis factor alpha (TNF-α). The combination of activated CD8+ T cells with any of the cytokines provided the best fits in young and aged animals. During the first 3 days after infection, the basic reproductive number for aged mice was 1.5-fold lower than that for young mice (P < 0.05). IMPORTANCE The fits of our models to the experimental data suggest that the increased levels of IFN-α/β, IFN-γ, and TNF-α (the “inflammaging” state) promote slower viral growth in aged mice, which consequently limits the stimulation of immune cells and contributes to the reported impaired responses in the elderly. A quantitative understanding of influenza virus pathogenesis and its shift in the elderly is the key contribution of this work. PMID:24478442

  4. Beech Fructification and Bank Vole Population Dynamics - Combined Analyses of Promoters of Human Puumala Virus Infections in Germany

    PubMed Central

    Reil, Daniela; Imholt, Christian; Eccard, Jana Anja; Jacob, Jens

    2015-01-01

    The transmission of wildlife zoonoses to humans depends, amongst others, on complex interactions of host population ecology and pathogen dynamics within host populations. In Europe, the Puumala virus (PUUV) causes nephropathia epidemica in humans. In this study we investigated complex interrelations within the epidemic system of PUUV and its rodent host, the bank vole (Myodes glareolus). We suggest that beech fructification and bank vole abundance are both decisive factors affecting human PUUV infections. While rodent host dynamics are expected to be directly linked to human PUUV infections, beech fructification is a rather indirect predictor by serving as food source for PUUV rodent hosts. Furthermore, we examined the dependence of bank vole abundance on beech fructification. We analysed a 12-year (2001-2012) time series of the parameters: beech fructification (as food resource for the PUUV host), bank vole abundance and human incidences from 7 Federal States of Germany. For the first time, we could show the direct interrelation between these three parameters involved in human PUUV epidemics and we were able to demonstrate on a large scale that human PUUV infections are highly correlated with bank vole abundance in the present year, as well as beech fructification in the previous year. By using beech fructification and bank vole abundance as predictors in one model we significantly improved the degree of explanation of human PUUV incidence. Federal State was included as random factor because human PUUV incidence varies considerably among states. Surprisingly, the effect of rodent abundance on human PUUV infections is less strong compared to the indirect effect of beech fructification. Our findings are useful to facilitate the development of predictive models for host population dynamics and the related PUUV infection risk for humans and can be used for plant protection and human health protection purposes. PMID:26214509

  5. Beech Fructification and Bank Vole Population Dynamics--Combined Analyses of Promoters of Human Puumala Virus Infections in Germany.

    PubMed

    Reil, Daniela; Imholt, Christian; Eccard, Jana Anja; Jacob, Jens

    2015-01-01

    The transmission of wildlife zoonoses to humans depends, amongst others, on complex interactions of host population ecology and pathogen dynamics within host populations. In Europe, the Puumala virus (PUUV) causes nephropathia epidemica in humans. In this study we investigated complex interrelations within the epidemic system of PUUV and its rodent host, the bank vole (Myodes glareolus). We suggest that beech fructification and bank vole abundance are both decisive factors affecting human PUUV infections. While rodent host dynamics are expected to be directly linked to human PUUV infections, beech fructification is a rather indirect predictor by serving as food source for PUUV rodent hosts. Furthermore, we examined the dependence of bank vole abundance on beech fructification. We analysed a 12-year (2001-2012) time series of the parameters: beech fructification (as food resource for the PUUV host), bank vole abundance and human incidences from 7 Federal States of Germany. For the first time, we could show the direct interrelation between these three parameters involved in human PUUV epidemics and we were able to demonstrate on a large scale that human PUUV infections are highly correlated with bank vole abundance in the present year, as well as beech fructification in the previous year. By using beech fructification and bank vole abundance as predictors in one model we significantly improved the degree of explanation of human PUUV incidence. Federal State was included as random factor because human PUUV incidence varies considerably among states. Surprisingly, the effect of rodent abundance on human PUUV infections is less strong compared to the indirect effect of beech fructification. Our findings are useful to facilitate the development of predictive models for host population dynamics and the related PUUV infection risk for humans and can be used for plant protection and human health protection purposes. PMID:26214509

  6. Population dynamics and sex ratio of a parasitoid altered by fungal-infected diet of host butterfly

    PubMed Central

    van Nouhuys, Saskya; Laine, Anna-Liisa

    2008-01-01

    Variation of host quality affects population dynamics of parasitoids, even at the landscape scale. What causes host quality to vary and the subsequent mechanisms by which parasitoid population dynamics are affected can be complex. Here, we examine the indirect interaction of a plant pathogen with a parasitoid wasp. Under laboratory conditions, parasitoids from hosts fed fungus-infected plants weighed less than those from hosts fed uninfected plants,. indicating that the fungus causes the hosts to be of poor quality. However, parasitoids reared from hosts fed fungal-infected diet also tended to be female, a characteristic associated with high host quality. The pathogen, herbivore and parasitoid persist regionally as metapopulations in a shared landscape in Åland, Finland. In an analysis of the metapopulation dynamics of the parasitoid over 6 years, the probability of colonization of a host population increased by more than twofold in patches occupied by the plant pathogen. While we cannot determine that the relationship is causal, a compelling explanation is that the plant pathogen facilitates the establishment by the parasitoid by increasing the fraction of female offspring. This is a novel mechanism of spatial multi-trophic level interactions. PMID:18182367

  7. Changing facial affect recognition in schizophrenia: effects of training on brain dynamics.

    PubMed

    Popova, Petia; Popov, Tzvetan G; Wienbruch, Christian; Carolus, Almut M; Miller, Gregory A; Rockstroh, Brigitte S

    2014-01-01

    Deficits in social cognition including facial affect recognition and their detrimental effects on functional outcome are well established in schizophrenia. Structured training can have substantial effects on social cognitive measures including facial affect recognition. Elucidating training effects on cortical mechanisms involved in facial affect recognition may identify causes of dysfunctional facial affect recognition in schizophrenia and foster remediation strategies. In the present study, 57 schizophrenia patients were randomly assigned to (a) computer-based facial affect training that focused on affect discrimination and working memory in 20 daily 1-hour sessions, (b) similarly intense, targeted cognitive training on auditory-verbal discrimination and working memory, or (c) treatment as usual. Neuromagnetic activity was measured before and after training during a dynamic facial affect recognition task (5 s videos showing human faces gradually changing from neutral to fear or to happy expressions). Effects on 10-13 Hz (alpha) power during the transition from neutral to emotional expressions were assessed via MEG based on previous findings that alpha power increase is related to facial affect recognition and is smaller in schizophrenia than in healthy subjects. Targeted affect training improved overt performance on the training tasks. Moreover, alpha power increase during the dynamic facial affect recognition task was larger after affect training than after treatment-as-usual, though similar to that after targeted perceptual-cognitive training, indicating somewhat nonspecific benefits. Alpha power modulation was unrelated to general neuropsychological test performance, which improved in all groups. Results suggest that specific neural processes supporting facial affect recognition, evident in oscillatory phenomena, are modifiable. This should be considered when developing remediation strategies targeting social cognition in schizophrenia.

  8. Vancomycin-resistant enterococci in intensive-care hospital settings: Transmission dynamics, persistence, and the impact of infection control programs

    PubMed Central

    Austin, Daren J.; Bonten, Marc J. M.; Weinstein, Robert A.; Slaughter, Sarah; Anderson, Roy M.

    1999-01-01

    Vancomycin-resistant enterococci (VRE) recently have emerged as a nosocomial pathogen especially in intensive-care units (ICUs) worldwide. Transmission via the hands of health-care workers is an important determinant of spread and persistence in a VRE-endemic ICU. We describe the transmission of nosocomial pathogens by using a micro-epidemiological framework based on the transmission dynamics of vector-borne diseases. By using the concept of a basic reproductive number, R0, defined as the average number of secondary cases generated by one primary case, we show quantitatively how infection control measures such as hand washing, cohorting, and antibiotic restriction affect nosocomial cross-transmission. By using detailed molecular epidemiological surveillance and compliance monitoring, we found that the estimated basic reproductive number for VRE during a study at the Cook County Hospital, Chicago, was approximately 3–4 without infection control and 0.7 when infection control measures were included. The impact of infection control was to reduce the prevalence from a predicted 79% to an observed 36%. Hand washing and staff cohorting are the most powerful control measures although their efficacy depends on the magnitude of R0. Under the circumstances tested, endemicity of VRE was stabilized despite infection control measures, by the constant introduction of colonized patients. Multiple stochastic simulations of the model revealed excellent agreement with observed pattern. In conjunction with detailed microbiological surveillance, a mathematical framework provides a precise template to describe the colonization dynamics of VRE in ICUs and impact of infection control measures. Our analyses suggest that compliance for hand washing significantly in excess of reported levels, or the cohorting of nursing staff, are needed to prevent nosocomial transmission of VRE in endemic settings. PMID:10359812

  9. Influence of maternal infections on neonatal acute phase proteins and their interaction in the development of non-affective psychosis

    PubMed Central

    Blomström, Å; Gardner, R M; Dalman, C; Yolken, R H; Karlsson, H

    2015-01-01

    Although primary infections with Toxoplasma gondii or herpes viruses during pregnancy are established teratogens, chronic maternal infections with these pathogens are considered far less serious. However, such chronic infections have been associated with neuropsychiatric disorders in the offspring. The risks of non-affective psychoses, including schizophrenia, in offspring associated with these exposures during pregnancy have not been completely defined. We used data from neonatal dried blood samples from 199 cases of non-affective psychosis and 525 matched controls (born 1975–1985). We measure immunoglobulin G antibodies directed at T. gondii, cytomegalovirus and herpes simplex virus type-1 and -2, as well as levels of nine acute phase proteins (APPs). We assessed the interaction between maternal antibodies and neonatal APP in terms of risk of non-affective psychosis. Among controls, maternal exposure to T. gondii or cytomegalovirus, but not to the other herpes viruses, was associated with significantly higher levels of neonatal APPs. Among cases, none of the maternal exposures were associated with any significant change in APPs. We observed increased RR for non-affective psychosis associated with maternal infection with T. gondii (odds ratio 2.1, 95% confidence interval 1.1–4.0) or cytomegalovirus (1.7, 0.9–3.3) only among neonates with low APP levels. These findings suggest that chronic maternal infection with T. gondii or cytomegalovirus affect neonatal markers of innate immunity. Deficient fetal immune responses in combination with maternal chronic infections may contribute to subsequent risk for psychosis. A greater understanding of the maternal–fetal immunological interplay may ultimately lead to preventive strategies toward neuropsychiatric disorders. PMID:25646591

  10. Host-parasite coevolutionary dynamics with generalized success/failure infection genetics.

    PubMed

    Engelstädter, Jan

    2015-05-01

    Host-parasite infection genetics can be more complex than envisioned by classic models such as the gene-for-gene or matching-allele models. By means of a mathematical model, I investigate the coevolutionary dynamics arising from a large set of generalized models of infection genetics in which hosts are either fully resistant or fully susceptible to a parasite, depending on the genotype of both individuals. With a single diploid interaction locus in the hosts, many of the infection genetic models produce stable or neutrally stable genotype polymorphisms. However, only a few models, which are all different versions of the matching-allele model, lead to sustained cycles of genotype frequency fluctuations in both interacting species ("Red Queen" dynamics). By contrast, with two diploid interaction loci in the hosts, many infection genetics models that cannot be classified as one of the standard infection genetics models produce Red Queen dynamics. Sexual versus asexual reproduction and, in the former case, the rate of recombination between the interaction loci have a large impact on whether Red Queen dynamics arise from a given infection genetics model. This may have interesting but as yet unexplored implications with respect to the Red Queen hypothesis for the evolution of sex.

  11. The burden of acute respiratory infections in crisis-affected populations: a systematic review

    PubMed Central

    2010-01-01

    Crises due to armed conflict, forced displacement and natural disasters result in excess morbidity and mortality due to infectious diseases. Historically, acute respiratory infections (ARIs) have received relatively little attention in the humanitarian sector. We performed a systematic review to generate evidence on the burden of ARI in crises, and inform prioritisation of relief interventions. We identified 36 studies published since 1980 reporting data on the burden (incidence, prevalence, proportional morbidity or mortality, case-fatality, attributable mortality rate) of ARI, as defined by the International Classification of Diseases, version 10 and as diagnosed by a clinician, in populations who at the time of the study were affected by natural disasters, armed conflict, forced displacement, and nutritional emergencies. We described studies and stratified data by age group, but did not do pooled analyses due to heterogeneity in case definitions. The published evidence, mainly from refugee camps and surveillance or patient record review studies, suggests very high excess morbidity and mortality (20-35% proportional mortality) and case-fatality (up to 30-35%) due to ARI. However, ARI disease burden comparisons with non-crisis settings are difficult because of non-comparability of data. Better epidemiological studies with clearer case definitions are needed to provide the evidence base for priority setting and programme impact assessments. Humanitarian agencies should include ARI prevention and control among infants, children and adults as priority activities in crises. Improved data collection, case management and vaccine strategies will help to reduce disease burden. PMID:20181220

  12. The burden of acute respiratory infections in crisis-affected populations: a systematic review.

    PubMed

    Bellos, Anna; Mulholland, Kim; O'Brien, Katherine L; Qazi, Shamim A; Gayer, Michelle; Checchi, Francesco

    2010-01-01

    Crises due to armed conflict, forced displacement and natural disasters result in excess morbidity and mortality due to infectious diseases. Historically, acute respiratory infections (ARIs) have received relatively little attention in the humanitarian sector. We performed a systematic review to generate evidence on the burden of ARI in crises, and inform prioritisation of relief interventions. We identified 36 studies published since 1980 reporting data on the burden (incidence, prevalence, proportional morbidity or mortality, case-fatality, attributable mortality rate) of ARI, as defined by the International Classification of Diseases, version 10 and as diagnosed by a clinician, in populations who at the time of the study were affected by natural disasters, armed conflict, forced displacement, and nutritional emergencies. We described studies and stratified data by age group, but did not do pooled analyses due to heterogeneity in case definitions. The published evidence, mainly from refugee camps and surveillance or patient record review studies, suggests very high excess morbidity and mortality (20-35% proportional mortality) and case-fatality (up to 30-35%) due to ARI. However, ARI disease burden comparisons with non-crisis settings are difficult because of non-comparability of data. Better epidemiological studies with clearer case definitions are needed to provide the evidence base for priority setting and programme impact assessments. Humanitarian agencies should include ARI prevention and control among infants, children and adults as priority activities in crises. Improved data collection, case management and vaccine strategies will help to reduce disease burden. PMID:20181220

  13. Host immunity shapes the impact of climate changes on the dynamics of parasite infections

    PubMed Central

    Mignatti, Andrea; Boag, Brian; Cattadori, Isabella M.

    2016-01-01

    Global climate change is predicted to alter the distribution and dynamics of soil-transmitted helminth infections, and yet host immunity can also influence the impact of warming on host–parasite interactions and mitigate the long-term effects. We used time-series data from two helminth species of a natural herbivore and investigated the contribution of climate change and immunity on the long-term and seasonal dynamics of infection. We provide evidence that climate warming increases the availability of infective stages of both helminth species and the proportional increase in the intensity of infection for the helminth not regulated by immunity. In contrast, there is no significant long-term positive trend in the intensity for the immune-controlled helminth, as immunity reduces the net outcome of climate on parasite dynamics. Even so, hosts experienced higher infections of this helminth at an earlier age during critical months in the warmer years. Immunity can alleviate the expected long-term effect of climate on parasite infections but can also shift the seasonal peak of infection toward the younger individuals. PMID:26884194

  14. Faecal egg counts and expulsion dynamics of the whipworm, Trichuris trichiura following self-infection.

    PubMed

    Hansen, E P; Tejedor, A M; Thamsborg, S M; Alstrup Hansen, T V; Dahlerup, J F; Nejsum, P

    2016-05-01

    More than 400 million humans are estimated to be infected with the intestinal helminth parasite, Trichuris trichiura. The infection is chronic in nature and high-intensity infection can lead to colitis, anaemia, Trichuris Dysentery Syndrome and reduced cognitive performance. Single doses of 400 mg albendazole or 500 mg mebendazole (MBZ) are used in mass drug administration programmes, but this has been shown to be insufficient. In this study, worm expulsion dynamics are described after MBZ treatment, given as a multi-dose and single-dose treatment in two separate T. trichiura self-infection studies. Worm expulsion dynamics post-treatment showed a similar pattern regardless of the dose regime, with the first worms observed on day 2 and the last worms expelled on days 9 and 13 post-treatment. Establishment of a chronic infection was observed following the inefficient single-dose treatment. The prepatent period was 13-16 weeks in both studies and worms were found to have a lifespan of at least 1 year and 10 months. These self-infection studies provide key information on the chronicity of T. trichiura infections, expulsion dynamics after anthelmintic treatment and the prepatent period, as well as the fecundity of female worms, which was around 18,000 eggs/female per day.

  15. Dynamics and establishment of Clostridium difficile infection in the murine gastrointestinal tract.

    PubMed

    Koenigsknecht, Mark J; Theriot, Casey M; Bergin, Ingrid L; Schumacher, Cassie A; Schloss, Patrick D; Young, Vincent B

    2015-03-01

    Clostridium difficile infection (CDI) following antibiotic therapy is a major public health threat. While antibiotic disruption of the indigenous microbiota underlies the majority of cases of CDI, the early dynamics of infection in the disturbed intestinal ecosystem are poorly characterized. This study defines the dynamics of infection with C. difficile strain VPI 10463 throughout the gastrointestinal (GI) tract using a murine model of infection. After inducing susceptibility to C. difficile colonization via antibiotic administration, we followed the dynamics of spore germination, colonization, sporulation, toxin activity, and disease progression throughout the GI tract. C. difficile spores were able to germinate within 6 h postchallenge, resulting in the establishment of vegetative bacteria in the distal GI tract. Spores and cytotoxin activity were detected by 24 h postchallenge, and histopathologic colitis developed by 30 h. Within 36 h, all infected mice succumbed to infection. We correlated the establishment of infection with changes in the microbiota and bile acid profile of the small and large intestines. Antibiotic administration resulted in significant changes to the microbiota in the small and large intestines, as well as a significant shift in the abundance of primary and secondary bile acids. Ex vivo analysis suggested the small intestine as the site of spore germination. This study provides an integrated understanding of the timing and location of the events surrounding C. difficile colonization and identifies potential targets for the development of new therapeutic strategies.

  16. Host immunity shapes the impact of climate changes on the dynamics of parasite infections.

    PubMed

    Mignatti, Andrea; Boag, Brian; Cattadori, Isabella M

    2016-03-15

    Global climate change is predicted to alter the distribution and dynamics of soil-transmitted helminth infections, and yet host immunity can also influence the impact of warming on host-parasite interactions and mitigate the long-term effects. We used time-series data from two helminth species of a natural herbivore and investigated the contribution of climate change and immunity on the long-term and seasonal dynamics of infection. We provide evidence that climate warming increases the availability of infective stages of both helminth species and the proportional increase in the intensity of infection for the helminth not regulated by immunity. In contrast, there is no significant long-term positive trend in the intensity for the immune-controlled helminth, as immunity reduces the net outcome of climate on parasite dynamics. Even so, hosts experienced higher infections of this helminth at an earlier age during critical months in the warmer years. Immunity can alleviate the expected long-term effect of climate on parasite infections but can also shift the seasonal peak of infection toward the younger individuals. PMID:26884194

  17. Host immunity shapes the impact of climate changes on the dynamics of parasite infections.

    PubMed

    Mignatti, Andrea; Boag, Brian; Cattadori, Isabella M

    2016-03-15

    Global climate change is predicted to alter the distribution and dynamics of soil-transmitted helminth infections, and yet host immunity can also influence the impact of warming on host-parasite interactions and mitigate the long-term effects. We used time-series data from two helminth species of a natural herbivore and investigated the contribution of climate change and immunity on the long-term and seasonal dynamics of infection. We provide evidence that climate warming increases the availability of infective stages of both helminth species and the proportional increase in the intensity of infection for the helminth not regulated by immunity. In contrast, there is no significant long-term positive trend in the intensity for the immune-controlled helminth, as immunity reduces the net outcome of climate on parasite dynamics. Even so, hosts experienced higher infections of this helminth at an earlier age during critical months in the warmer years. Immunity can alleviate the expected long-term effect of climate on parasite infections but can also shift the seasonal peak of infection toward the younger individuals.

  18. Repeatable Population Dynamics among Vesicular Stomatitis Virus Lineages Evolved under High Co-infection

    PubMed Central

    Williams, Elizabeth S. C. P.; Morales, Nadya M.; Wasik, Brian R.; Brusic, Vesna; Whelan, Sean P. J.; Turner, Paul E.

    2016-01-01

    Parasites and hosts can experience oscillatory cycles, where the densities of these interacting species dynamically fluctuate through time. Viruses with different replication strategies can also interact to produce cyclical dynamics. Frequent cellular co-infection can select for defective-interfering particles (DIPs): “cheater” viruses with shortened genomes that interfere with intracellular replication of full-length (ordinary) viruses. DIPs are positively selected when rare because they out-replicate ordinary viruses during co-infection, but DIPs are negatively selected when common because ordinary viruses become unavailable for intracellular exploitation via cheating. Here, we tested whether oscillatory dynamics of ordinary viruses were similar across independently evolved populations of vesicular stomatitis virus (VSV). Results showed identical cyclical dynamics across populations in the first 10 experimental passages, which transitioned to repeatable dampened oscillations by passage 20. Genomic analyses revealed parallel molecular substitutions across populations, particularly novel mutations that became dominant by passage 10. Our study showed that oscillatory dynamics and molecular evolution of interacting viruses were highly repeatable in VSV populations passaged under frequent co-infection. Furthermore, our data suggested that frequent co-infection with DIPs caused lowered performance of full-length viruses, by reducing their population densities by orders of magnitude compared to reproduction of ordinary viruses during strictly clonal infections. PMID:27065953

  19. Repeatable Population Dynamics among Vesicular Stomatitis Virus Lineages Evolved under High Co-infection.

    PubMed

    Williams, Elizabeth S C P; Morales, Nadya M; Wasik, Brian R; Brusic, Vesna; Whelan, Sean P J; Turner, Paul E

    2016-01-01

    Parasites and hosts can experience oscillatory cycles, where the densities of these interacting species dynamically fluctuate through time. Viruses with different replication strategies can also interact to produce cyclical dynamics. Frequent cellular co-infection can select for defective-interfering particles (DIPs): "cheater" viruses with shortened genomes that interfere with intracellular replication of full-length (ordinary) viruses. DIPs are positively selected when rare because they out-replicate ordinary viruses during co-infection, but DIPs are negatively selected when common because ordinary viruses become unavailable for intracellular exploitation via cheating. Here, we tested whether oscillatory dynamics of ordinary viruses were similar across independently evolved populations of vesicular stomatitis virus (VSV). Results showed identical cyclical dynamics across populations in the first 10 experimental passages, which transitioned to repeatable dampened oscillations by passage 20. Genomic analyses revealed parallel molecular substitutions across populations, particularly novel mutations that became dominant by passage 10. Our study showed that oscillatory dynamics and molecular evolution of interacting viruses were highly repeatable in VSV populations passaged under frequent co-infection. Furthermore, our data suggested that frequent co-infection with DIPs caused lowered performance of full-length viruses, by reducing their population densities by orders of magnitude compared to reproduction of ordinary viruses during strictly clonal infections. PMID:27065953

  20. Emergence of elevated levels of multiple infections in spatial host-virus dynamics

    NASA Astrophysics Data System (ADS)

    Taylor, Bradford; Penington, Catherine; Weitz, Joshua

    Bacteria are subject to infection and potentially to multiple simultaneous infections by viruses. Multiply infected hosts have altered life-history traits (e.g., viral burst size) and evolutionary rates (e.g., viral recombination). Yet our understanding of multiple infections of microbes is limited to lab settings where the ratio of inoculant viruses to hosts is controlled. In contrast, rates of multiple infection in natural environments are unknown. Here, we develop an individual based model to quantify rates of multiple infections by a single viral type. We explore different dispersal regimes by varying the viral adsorption rate. High dispersal regimes lead to spatial dynamics and rates of multiple infection equivalent to predictions from mean field models. Local clustering of bacterial hosts occurs for low dispersal. Comparing to mean field, the clustering leads to increased rates of multiple infection and fatter tails in the distribution of the number of internal viruses. The emergence of increased colocalization of viruses with infected hosts leads to these deviations. We show these deviations result from the wave-like spread of viruses when invading clusters of bacteria. Our work represents a key step in understanding the population-level effects of multiple infections.

  1. Ascaris suum infection negatively affects the response to a Mycoplasma hyopneumoniae vaccination and subsequent challenge infection in pigs

    Technology Transfer Automated Retrieval System (TEKTRAN)

    It is vital to understand the possible mechanisms that may impair optimal vaccine efficacy. The hypothesis posed in this study was that a concurrent Ascaris suum infection of pigs vaccinated with a Mycoplasma hyopneumoniae (Mh) vaccine would modulate the protective immune response to a subsequent ch...

  2. Investigating the Effects of Sweat Therapy on Group Dynamics and Affect

    ERIC Educational Resources Information Center

    Colmant, Stephen A.; Eason, Evan A.; Winterowd, Carrie L.; Jacobs, Sue C.; Cashel, Chris

    2005-01-01

    In this study, we examined the effects of sweat therapy on group dynamics and affect. Sweat therapy is the combination of intense heat exposure with psychotherapy or counseling (Colmant & Merta, 1999; 2000). Twenty-four undergraduates were separated by sex and randomly assigned to eight sessions of either a sweat or non-sweat group counseling…

  3. Environmental Factors Affecting Computer Assisted Language Learning Success: A Complex Dynamic Systems Conceptual Model

    ERIC Educational Resources Information Center

    Marek, Michael W.; Wu, Wen-Chi Vivian

    2014-01-01

    This conceptual, interdisciplinary inquiry explores Complex Dynamic Systems as the concept relates to the internal and external environmental factors affecting computer assisted language learning (CALL). Based on the results obtained by de Rosnay ["World Futures: The Journal of General Evolution", 67(4/5), 304-315 (2011)], who observed…

  4. Dynamics of neutrophil migration in lymph nodes during infection

    PubMed Central

    Chtanova, Tatyana; Schaeffer, Marie; Han, Seong-Ji; van Dooren, Giel G.; Nollmann, Marcelo; Herzmark, Paul; Chan, Shiao Wei; Satija, Harshita; Camfield, Kristin; Aaron, Holly; Striepen, Boris; Robey, Ellen A.

    2008-01-01

    Summary While the signals that control neutrophil migration from the blood to sites of infection have been well characterized, little is known about their migration patterns within lymph nodes, or the strategies that neutrophils use to find their local sites of action. To address these questions, we used two-photon scanning laser microscopy (TPSLM) to examine neutrophil migration in intact lymph nodes during infection with an intracellular parasite, Toxoplasma gondii. We find that neutrophils form both small, transient or large, persistent swarms via a strikingly coordinated migration pattern. We provide evidence that cooperative action of neutrophils and parasite egress from host cells can trigger swarm formation. Neutrophil swarm formation coincides in space and time with the removal of macrophages that line the subcapsular sinus of the lymph node. Our data provide insights into the cellular mechanisms underlying neutrophil swarming and suggest new roles for neutrophils in shaping immune responses. PMID:18718768

  5. Fluctuations in Electronic Energy Affecting Singlet Fission Dynamics and Mixing with Charge-Transfer State: Quantum Dynamics Study.

    PubMed

    Fujihashi, Yuta; Ishizaki, Akihito

    2016-02-01

    Singlet fission is a spin-allowed process by which a singlet excited state is converted to two triplet states. To understand mechanisms of the ultrafast fission via a charge transfer (CT) state, one has investigated the dynamics through quantum-dynamical calculations with the uncorrelated fluctuation model; however, the electronic states are expected to experience the same fluctuations induced by the surrounding molecules because the electronic structure of the triplet pair state is similar to that of the singlet state except for the spin configuration. Therefore, the fluctuations in the electronic energies could be correlated, and the 1D reaction coordinate model may adequately describe the fission dynamics. In this work we develop a model for describing the fission dynamics to explain the experimentally observed behaviors. We also explore impacts of fluctuations in the energy of the CT state on the fission dynamics and the mixing with the CT state. The overall behavior of the dynamics is insensitive to values of the reorganization energy associated with the transition from the singlet state to the CT state, although the coherent oscillation is affected by the fluctuations. This result indicates that the mixing with the CT state is rather robust under the fluctuations in the energy of the CT state as well as the high-lying CT state. PMID:26732701

  6. Very Young Children Affected and Infected by HIV/AIDS: How are they Living?: A Case Study from Namibia

    ERIC Educational Resources Information Center

    Hayden, Jacqueline; Otaala, Barnabas

    2005-01-01

    This paper describes a recent study conducted jointly by the authors in the Khomas Region of Namibia. The study developed and trialled research and documentation methods regarding very young children who had been infected or affected by the HIV/AIDS pandemic. Because of the stigma attached to the disease, effective methods for assessing "real"…

  7. Temporary treatment during primary HIV infection does not affect virologic response to subsequent long-term treatment.

    PubMed

    Grijsen, Marlous L; Wit, Ferdinand W N M; Jurriaans, Suzanne; Kroon, Frank P; Schippers, Emile F; Koopmans, Peter; Gras, Luuk; Lange, Joep M A; Prins, Jan M

    2014-01-01

    Temporary cART during primary HIV-infection (PHI) did not select for drug resistance mutations after treatment interruption and did not affect the subsequent virological response to long-term cART. Our data demonstrate that fear of drug resistance development is not a valid argument to refrain from temporary early treatment during PHI.

  8. Echinococcus granulosus infection dynamics in livestock of Greece.

    PubMed

    Chaligiannis, I; Maillard, S; Boubaker, G; Spiliotis, M; Saratsis, A; Gottstein, B; Sotiraki, S

    2015-10-01

    An epidemiological and molecular survey on the occurrence of Echinococcus hydatid cysts in livestock was conducted in Greece. In total 898 sheep, 483 goats, 38 buffaloes, 273 wild boars and 15 deer were examined and 30.2% (6.45% cyst fertility), 7.86% (3.2% cyst fertility), 42% (7.9% cyst fertility), 1.1% (0% cyst fertility), 0% of them were found infected, respectively. Infection rate in different geographical regions varied between 26.1 and 53.8% (cyst fertility 2.04 and 34.6%) in sheep, 7.33 and 13.3% (cyst fertility 0 and 3.2%) in goats. Genotyping, based on cox1 and nad1 analyses, demonstrated the predominance of E. granulosus s.s. (G1 genotype). The presence of one single genotype-complex within a relatively large spectrum of intermediate host species in Greece indicates the presence of a dominant transmission dog-sheep cycle involving additional host species which may act as disease reservoir for human infections.

  9. Within-Host Spatiotemporal Dynamics of Plant Virus Infection at the Cellular Level

    PubMed Central

    Lafforgue, Guillaume; Elena, Santiago F.

    2014-01-01

    A multicellular organism is not a monolayer of cells in a flask; it is a complex, spatially structured environment, offering both challenges and opportunities for viruses to thrive. Whereas virus infection dynamics at the host and within-cell levels have been documented, the intermediate between-cell level remains poorly understood. Here, we used flow cytometry to measure the infection status of thousands of individual cells in virus-infected plants. This approach allowed us to determine accurately the number of cells infected by two virus variants in the same host, over space and time as the virus colonizes the host. We found a low overall frequency of cellular infection (<0.3), and few cells were coinfected by both virus variants (<0.1). We then estimated the cellular contagion rate (R), the number of secondary infections per infected cell per day. R ranged from 2.43 to values not significantly different from zero, and generally decreased over time. Estimates of the cellular multiplicity of infection (MOI), the number of virions infecting a cell, were low (<1.5). Variance of virus-genotype frequencies increased strongly from leaf to cell levels, in agreement with a low MOI. Finally, there were leaf-dependent differences in the ease with which a leaf could be colonized, and the number of virions effectively colonizing a leaf. The modeling of infection patterns suggests that the aggregation of virus-infected cells plays a key role in limiting spread; matching the observation that cell-to-cell movement of plant viruses can result in patches of infection. Our results show that virus expansion at the between-cell level is restricted, probably due to the host environment and virus infection itself. PMID:24586207

  10. Dynamics of a Class of HIV Infection Models with Cure of Infected Cells in Eclipse Stage.

    PubMed

    Maziane, Mehdi; Lotfi, El Mehdi; Hattaf, Khalid; Yousfi, Noura

    2015-12-01

    In this paper, we propose two HIV infection models with specific nonlinear incidence rate by including a class of infected cells in the eclipse phase. The first model is described by ordinary differential equations (ODEs) and generalizes a set of previously existing models and their results. The second model extends our ODE model by taking into account the diffusion of virus. Furthermore, the global stability of both models is investigated by constructing suitable Lyapunov functionals. Finally, we check our theoretical results with numerical simulations.

  11. Clonorchis sinensis Co-infection Could Affect the Disease State and Treatment Response of HBV Patients

    PubMed Central

    Huang, Yan; Chen, Tingjin; Kong, Xiangzhan; Sun, Hengchang; Yu, Xinbing; Xu, Jin

    2016-01-01

    Background Clonorchis sinensis (C. sinensis) is considered to be an important parasitic zoonosis because it infects approximately 35 million people, while approximately 15 million were distributed in China. Hepatitis B virus (HBV) infection is a major public health issue. Two types of pathogens have the potential to cause human liver disease and eventually hepatocellular carcinoma. Concurrent infection with HBV and C. sinensis is often observed in some areas where C. sinensis is endemic. However, whether C. sinensis could impact HBV infection or vice versa remains unknown. Principal Findings Co-infection with C. sinensis and HBV develops predominantly in males. Co-infected C. sinensis and HBV patients presented weaker liver function and higher HBV DNA titers. Combination treatment with antiviral and anti-C. sinensis drugs in co-infected patients could contribute to a reduction in viral load and help with liver function recovery. Excretory-secretory products (ESPs) may, in some ways, increase HBV viral replication in vitro. A mixture of ESP and HBV positive sera could induce peripheral blood mononuclear cells (PBMCs) to produce higher level of Th2 cytokines including IL-4, IL-6 and IL-10 compared to HBV alone, it seems that due to presence of ESP, the cytokine production shift towards Th2. C. sinensis/HBV co-infected patients showed higher serum IL-6 and IL-10 levels and lower serum IFN-γ levels. Conclusions/Significance Patients with concomitant C. sinensis and HBV infection presented weaker liver function and higher HBV DNA copies. In co-infected patients, the efficacy of anti-viral treatment was better in patients who were prescribed with entecavir and praziquantel than entecavir alone. One possible reason for the weaker response to antiviral therapies in co-infected patients was the shift in cytokine production from Th1 to Th2 that may inhibit viral clearance. C. sinensis/HBV co-infection could exacerbate the imbalance of Th1/Th2 cytokine. PMID:27348302

  12. An investigation of factors affecting elementary school students' BMI values based on the system dynamics modeling.

    PubMed

    Lan, Tian-Syung; Chen, Kai-Ling; Chen, Pin-Chang; Ku, Chao-Tai; Chiu, Pei-Hsuan; Wang, Meng-Hsiang

    2014-01-01

    This study used system dynamics method to investigate the factors affecting elementary school students' BMI values. The construction of the dynamic model is divided into the qualitative causal loop and the quantitative system dynamics modeling. According to the system dynamics modeling, this study consisted of research on the four dimensions: student's personal life style, diet-relevant parenting behaviors, advocacy and implementation of school nutrition education, and students' peer interaction. The results of this study showed that students with more adequate health concepts usually have better eating behaviors and consequently have less chance of becoming obese. In addition, this study also verified that educational attainment and socioeconomic status of parents have a positive correlation with students' amounts of physical activity, and nutrition education has a prominent influence on changing students' high-calorie diets.

  13. Batrachochytrium dendrobatidis infection dynamics vary seasonally in upstate New York, USA.

    PubMed

    Lenker, Melissa A; Savage, Anna E; Becker, C Guilherme; Rodriguez, David; Zamudio, Kelly R

    2014-08-21

    The amphibian disease chytridiomycosis, caused by the fungus Batrachochytrium dendrobatidis (Bd), is a major cause of worldwide amphibian declines and extinctions. Although several studies indicate that Bd prevalence and infection intensity vary seasonally, temporal variation of Bd at high-latitude sites, such as the northeastern USA, is still poorly characterized. We screened amphibians for Bd monthly at 2 study sites in New York State from April to October 2011 and used quantitative polymerase chain reaction (qPCR) to detect and quantify temporal variability in Bd infection prevalence and intensity. We found pronounced seasonal variation in both Bd infection prevalence and intensity at the community level, and our data indicate that this pattern is due to a few species (Lithobates catesbeianus, L. clamitans, and Notophthalmus viridescens) that drive temporal variability in disease dynamics. Amphibian body mass and sex were significant predictors of infection intensity but not infection prevalence. Understanding the temporal dynamics of Bd host-pathogen interactions provides important insight into regional, seasonal, and host-specific determinants of disease outbreaks. Further, our study elucidates the most relevant and informative timing for Bd surveys in temperate amphibian assemblages. Seasonal variation of infection dynamics suggests that Bd surveys from different sampling time points are not comparable, and summer surveys to evaluate chytridiomycosis may significantly underestimate Bd prevalence and intensity, leading to false conclusions about the severity of chytridiomycosis-induced amphibian mortality and population decline.

  14. Factors Affecting Length of Hospital Stay and Mortality in Infected Diabetic Foot Ulcers Undergoing Surgical Drainage without Major Amputation.

    PubMed

    Kim, Tae Gyun; Moon, Sang Young; Park, Moon Seok; Kwon, Soon-Sun; Jung, Ki Jin; Lee, Taeseung; Kim, Baek Kyu; Yoon, Chan; Lee, Kyoung Min

    2016-01-01

    This study aimed to investigate factors affecting length of hospital stay and mortality of a specific group of patients with infected diabetic foot ulcer who underwent surgical drainage without major amputation, which is frequently encountered by orthopedic surgeons. Data on length of hospital stay, mortality, demographics, and other medical information were collected for 79 consecutive patients (60 men, 19 women; mean age, 66.1 [SD, 12.3] yr) with infected diabetic foot ulcer who underwent surgical drainage while retaining the heel between October 2003 and May 2013. Multiple linear regression analysis was performed to determine factors affecting length of hospital stay, while multiple Cox regression analysis was conducted to assess factors contributing to mortality. Erythrocyte sedimentation rate (ESR, P=0.034), glycated hemoglobin (HbA1c) level (P=0.021), body mass index (BMI, P=0.001), and major vascular disease (cerebrovascular accident or coronary artery disease, P=0.004) were significant factors affecting length of hospital stay, whereas age (P=0.005) and serum blood urea nitrogen (BUN) level (P=0.024) were significant factors contributing to mortality. In conclusion, as prognostic factors, the length of hospital stay was affected by the severity of inflammation, the recent control of blood glucose level, BMI, and major vascular disease, whereas patient mortality was affected by age and renal function in patients with infected diabetic foot ulcer undergoing surgical drainage and antibiotic treatment.

  15. Factors Affecting Length of Hospital Stay and Mortality in Infected Diabetic Foot Ulcers Undergoing Surgical Drainage without Major Amputation

    PubMed Central

    2016-01-01

    This study aimed to investigate factors affecting length of hospital stay and mortality of a specific group of patients with infected diabetic foot ulcer who underwent surgical drainage without major amputation, which is frequently encountered by orthopedic surgeons. Data on length of hospital stay, mortality, demographics, and other medical information were collected for 79 consecutive patients (60 men, 19 women; mean age, 66.1 [SD, 12.3] yr) with infected diabetic foot ulcer who underwent surgical drainage while retaining the heel between October 2003 and May 2013. Multiple linear regression analysis was performed to determine factors affecting length of hospital stay, while multiple Cox regression analysis was conducted to assess factors contributing to mortality. Erythrocyte sedimentation rate (ESR, P=0.034), glycated hemoglobin (HbA1c) level (P=0.021), body mass index (BMI, P=0.001), and major vascular disease (cerebrovascular accident or coronary artery disease, P=0.004) were significant factors affecting length of hospital stay, whereas age (P=0.005) and serum blood urea nitrogen (BUN) level (P=0.024) were significant factors contributing to mortality. In conclusion, as prognostic factors, the length of hospital stay was affected by the severity of inflammation, the recent control of blood glucose level, BMI, and major vascular disease, whereas patient mortality was affected by age and renal function in patients with infected diabetic foot ulcer undergoing surgical drainage and antibiotic treatment. PMID:26770047

  16. Assessing the effects of multiple infections and long latency in the dynamics of tuberculosis

    PubMed Central

    2010-01-01

    In order to achieve a better understanding of multiple infections and long latency in the dynamics of Mycobacterium tuberculosis infection, we analyze a simple model. Since backward bifurcation is well documented in the literature with respect to the model we are considering, our aim is to illustrate this behavior in terms of the range of variations of the model's parameters. We show that backward bifurcation disappears (and forward bifurcation occurs) if: (a) the latent period is shortened below a critical value; and (b) the rates of super-infection and re-infection are decreased. This result shows that among immunosuppressed individuals, super-infection and/or changes in the latent period could act to facilitate the onset of tuberculosis. When we decrease the incubation period below the critical value, we obtain the curve of the incidence of tuberculosis following forward bifurcation; however, this curve envelops that obtained from the backward bifurcation diagram. PMID:21059256

  17. Seasonal dynamics of Schistosoma japonicum infection in buffaloes in the Poyang Lake region and suggestions on local treatment schemes.

    PubMed

    Liu, Jin-Ming; Yu, Hua; Shi, Yao-Jun; Li, Hao; He, Liang; Li, Jian-Xi; Dong, Chang-Hua; Xie, Qiao; Jin, Ya-Mei; Lu, Ke; Lin, Jiao-Jiao

    2013-11-15

    Schistosomiasis japonica remains a major public health problem and the Poyang Lake region in Jiangxi province is one of the worst affected endemic areas. Buffaloes play a major role in the transmission of Schistosoma japonicum to humans. The aim of the present study was to increase understanding of the epidemic characteristics of schistosomiasis japonica in water buffaloes in the Poyang Lake region, after achieving the national mid-term goal, and to provide a basis for further interventions. The baseline prevalence in two villages in the Poyang Lake region in May 2010 was compared with respect to usage, sex and age in the total study population. Seasonal dynamics from May 2010 to May 2011 were observed in a natural village in the studied area. The baseline prevalence of infection in both villages (Caohui and Gaozhou) was 4.94% in May 2010. The prevalence in buffalo younger than 12 months was 12.82% in Caohui and 15.11% in Gaozhou, which was significantly higher than that found in those aged 13-24 months and older than 24 months. Of the 28 infected buffaloes, 82.14% (23) were younger than 12 months. The flow of seasonal dynamics showed that S. japonicum infection buffaloes were found from May to July and from November to January of the following year. This survey suggested that it is necessary to conduct two mass treatments (especially for young animals) in late March or early April and November, with an additional treatment of positive animals in July or June.

  18. Impact of external sources of infection on the dynamics of bovine tuberculosis in modelled badger populations

    PubMed Central

    2012-01-01

    Background The persistence of bovine TB (bTB) in various countries throughout the world is enhanced by the existence of wildlife hosts for the infection. In Britain and Ireland, the principal wildlife host for bTB is the badger (Meles meles). The objective of our study was to examine the dynamics of bTB in badgers in relation to both badger-derived infection from within the population and externally-derived, trickle-type, infection, such as could occur from other species or environmental sources, using a spatial stochastic simulation model. Results The presence of external sources of infection can increase mean prevalence and reduce the threshold group size for disease persistence. Above the threshold equilibrium group size of 6–8 individuals predicted by the model for bTB persistence in badgers based on internal infection alone, external sources of infection have relatively little impact on the persistence or level of disease. However, within a critical range of group sizes just below this threshold level, external infection becomes much more important in determining disease dynamics. Within this critical range, external infection increases the ratio of intra- to inter-group infections due to the greater probability of external infections entering fully-susceptible groups. The effect is to enable bTB persistence and increase bTB prevalence in badger populations which would not be able to maintain bTB based on internal infection alone. Conclusions External sources of bTB infection can contribute to the persistence of bTB in badger populations. In high-density badger populations, internal badger-derived infections occur at a sufficient rate that the additional effect of external sources in exacerbating disease is minimal. However, in lower-density populations, external sources of infection are much more important in enhancing bTB prevalence and persistence. In such circumstances, it is particularly important that control strategies to reduce bTB in badgers include

  19. Dynamic association between negative affect and alcohol lapses following alcohol treatment.

    PubMed

    Witkiewitz, Katie; Villarroel, Nadia Aracelliz

    2009-08-01

    Clinical research has found a strong association between negative affect and returning to alcohol use after a period of abstinence. Yet little is known about the probability of a lapse given a particular level of negative affect or whether there is a reciprocal relationship between negative affect and alcohol use across time. The goal of the current study was to examine the association between negative affect and drinking behavior in the 1st year following alcohol treatment. The authors applied an associative latent transition analysis to the Project MATCH outpatient data (n = 952) and then replicated the model in the Project MATCH aftercare data (n = 774). Changes in drinking following treatment were significantly associated with current and prior changes in negative affect, and changes in negative affect were related to prior changes in drinking (effect size range = 0.13-0.33). The results supported the hypothesis that negative affect and alcohol lapses are dynamically linked and suggest that targeting the relationship between negative affect and alcohol use could greatly decrease the probability of lapses and improve alcohol treatment outcomes. PMID:19634957

  20. Identifying Core Affect in Individuals from fMRI Responses to Dynamic Naturalistic Audiovisual Stimuli.

    PubMed

    Kim, Jongwan; Wang, Jing; Wedell, Douglas H; Shinkareva, Svetlana V

    2016-01-01

    Recent research has demonstrated that affective states elicited by viewing pictures varying in valence and arousal are identifiable from whole brain activation patterns observed with functional magnetic resonance imaging (fMRI). Identification of affective states from more naturalistic stimuli has clinical relevance, but the feasibility of identifying these states on an individual trial basis from fMRI data elicited by dynamic multimodal stimuli is unclear. The goal of this study was to determine whether affective states can be similarly identified when participants view dynamic naturalistic audiovisual stimuli. Eleven participants viewed 5s audiovisual clips in a passive viewing task in the scanner. Valence and arousal for individual trials were identified both within and across participants based on distributed patterns of activity in areas selectively responsive to audiovisual naturalistic stimuli while controlling for lower level features of the stimuli. In addition, the brain regions identified by searchlight analyses to represent valence and arousal were consistent with previously identified regions associated with emotion processing. These findings extend previous results on the distributed representation of affect to multimodal dynamic stimuli. PMID:27598534

  1. Dynamic Response of Large Wind Power Plant Affected by Diverse Conditions at Individual Turbines

    SciTech Connect

    Elizondo, Marcelo A.; Lu, Shuai; Lin, Guang; Wang, Shaobu

    2014-07-31

    Diverse operating conditions at individual wind turbine generators (WTG) within wind power plants (WPPs) can affect the WPP dynamic response to system faults. For example, individual WTGs can experience diverse terminal voltage and power output caused by different wind direction and speed, affecting the response of protection and control limiters. In this paper, we present a study to investigate the dynamic response of a detailed WPP model under diverse power outputs of its individual WTGs. Wake effect is considered as the reason for diverse power outputs. The diverse WTG power output is evaluated in a test system where a large 168-machine test WPP is connected to the IEEE-39-bus system. The power output from each WTG is derived from a wake effect model that uses realistic statistical data for incoming wind speed and direction. The results show that diverse WTG output due to wake effect can affect the WPP dynamic response activating specialized control in some turbines. In addition, transient stability is affected by exhibiting uncertainty in critical clearing time calculation.

  2. Identifying Core Affect in Individuals from fMRI Responses to Dynamic Naturalistic Audiovisual Stimuli

    PubMed Central

    Kim, Jongwan; Wang, Jing; Wedell, Douglas H.

    2016-01-01

    Recent research has demonstrated that affective states elicited by viewing pictures varying in valence and arousal are identifiable from whole brain activation patterns observed with functional magnetic resonance imaging (fMRI). Identification of affective states from more naturalistic stimuli has clinical relevance, but the feasibility of identifying these states on an individual trial basis from fMRI data elicited by dynamic multimodal stimuli is unclear. The goal of this study was to determine whether affective states can be similarly identified when participants view dynamic naturalistic audiovisual stimuli. Eleven participants viewed 5s audiovisual clips in a passive viewing task in the scanner. Valence and arousal for individual trials were identified both within and across participants based on distributed patterns of activity in areas selectively responsive to audiovisual naturalistic stimuli while controlling for lower level features of the stimuli. In addition, the brain regions identified by searchlight analyses to represent valence and arousal were consistent with previously identified regions associated with emotion processing. These findings extend previous results on the distributed representation of affect to multimodal dynamic stimuli. PMID:27598534

  3. Infection before pregnancy affects immunity and response to social challenge in the next generation.

    PubMed

    Curno, Olivia; Reader, Tom; McElligott, Alan G; Behnke, Jerzy M; Barnard, Chris J

    2011-12-12

    Natural selection should favour parents that are able to adjust their offspring's life-history strategy and resource allocation in response to changing environmental and social conditions. Pathogens impose particularly strong and variable selective pressure on host life histories, and parental genes will benefit if offspring are appropriately primed to meet the immunological challenges ahead. Here, we investigated transgenerational immune priming by examining reproductive resource allocation by female mice in response to direct infection with Babesia microti prior to pregnancy. Female mice previously infected with B. microti gained more weight over pregnancy, and spent more time nursing their offspring. These offspring generated an accelerated response to B. microti as adults, clearing the infection sooner and losing less weight as a result of infection. They also showed an altered hormonal response to novel social environments, decreasing instead of increasing testosterone production upon social housing. These results suggest that a dominance-resistance trade-off can be mediated by cues from the previous generation. We suggest that strategic maternal investment in response to an infection leads to increased disease resistance in the following generation. Offspring from previously infected mothers downregulate investment in acquisition of social dominance, which in natural systems would reduce access to mating opportunities. In doing so, however, they avoid the reduced disease resistance associated with increased testosterone and dominance. The benefits of accelerated clearance of infection and reduced weight loss during infection may outweigh costs associated with reduced social dominance in an environment where the risk of disease is high.

  4. Identifying the factors affecting phytoplankton abundance dynamics in Shihmen Reservoir, Taiwan

    NASA Astrophysics Data System (ADS)

    Kuo, Yi-Ming; Chuang, Illy; Chu, Hone-Jay; Wu, Jiunn-Tzong; Jang, Cheng-Shin

    2013-04-01

    Investigations of multiple temporal distributions of phytoplankton dynamics through environmental variables in water bodies over extensive areas remain relatively scarce. This study focused on the determination of the key factors regulating temporal and spatial variations of phytoplankton abundance at three monitoring sites in Shihmen Reservoir within five years (2006-2010). Dynamic factor analysis (DFA), a dimension-reduction technique, was designed to identify the underlying latent effects in multiple time series and interactions between explanatory variables (i.e., environmental variables) and the response variable (phytoplankton abundance). The optimal DFA model successfully described the dynamics of phytoplankton abundance in the Shihmen Reservoir. The results demonstrated that water temperature, water level, COD, BOD, and DO considerably affected phytoplankton abundance at most of the monitoring sites. Among them, water temperature, water level, and COD significantly affected phytoplankton abundance at all three sites, indicating that these variables contributed more to the long-term dynamics of phytoplankton abundance than other variables at the surface water of Shihmen Reservoir. The influx and efflux of Reservoir altering hydrological conditions in Shihmen Reservoir may attenuate the nutrients effects on phytoplankton abundance. In this study, BOD and DO are the other crucial water quality factors that control variations of phytoplankton. The explanatory variables mainly explain the dynamics of phytoplankton abundance than common trends do. In the future, the water manager may consider these variables to propose strategies to manage water quality in Shihmen Reservoir.

  5. Age-specific haemosporidian infection dynamics and survival in Seychelles warblers

    PubMed Central

    Hammers, Martijn; Komdeur, Jan; Kingma, Sjouke A.; Hutchings, Kimberly; Fairfield, Eleanor A.; Gilroy, Danielle L.; Richardson, David S.

    2016-01-01

    Parasites may severely impact the fitness and life-history of their hosts. After infection, surviving individuals may suppress the growth of the parasite, or completely clear the infection and develop immunity. Consequently, parasite prevalence is predicted to decline with age. Among elderly individuals, immunosenescence may lead to a late-life increase in infection prevalence. We used a 21-year longitudinal dataset from one population of individually-marked Seychelles warblers (Acrocephalus sechellensis) to investigate age-dependent prevalence of the GRW1 strain of the intracellular protozoan blood parasite Haemoproteus nucleocondensus and whether infections with this parasite affect age-dependent survival. We analyzed 2454 samples from 1431 individuals and found that H. nucleocondensus infections could rarely be detected in nestlings. Prevalence increased strongly among fledglings and peaked among older first year birds. Prevalence was high among younger adults and declined steeply until ca 4 years of age, after which it was stable. Contrary to expectations, H. nucleocondensus prevalence did not increase among elderly individuals and we found no evidence that annual survival was lower in individuals suffering from an infection. Our results suggest that individuals clear or suppress infections and acquire immunity against future infections, and provide no evidence for immunosenescence nor an impact of chronic infections on survival. PMID:27431430

  6. Age-specific haemosporidian infection dynamics and survival in Seychelles warblers.

    PubMed

    Hammers, Martijn; Komdeur, Jan; Kingma, Sjouke A; Hutchings, Kimberly; Fairfield, Eleanor A; Gilroy, Danielle L; Richardson, David S

    2016-01-01

    Parasites may severely impact the fitness and life-history of their hosts. After infection, surviving individuals may suppress the growth of the parasite, or completely clear the infection and develop immunity. Consequently, parasite prevalence is predicted to decline with age. Among elderly individuals, immunosenescence may lead to a late-life increase in infection prevalence. We used a 21-year longitudinal dataset from one population of individually-marked Seychelles warblers (Acrocephalus sechellensis) to investigate age-dependent prevalence of the GRW1 strain of the intracellular protozoan blood parasite Haemoproteus nucleocondensus and whether infections with this parasite affect age-dependent survival. We analyzed 2454 samples from 1431 individuals and found that H. nucleocondensus infections could rarely be detected in nestlings. Prevalence increased strongly among fledglings and peaked among older first year birds. Prevalence was high among younger adults and declined steeply until ca 4 years of age, after which it was stable. Contrary to expectations, H. nucleocondensus prevalence did not increase among elderly individuals and we found no evidence that annual survival was lower in individuals suffering from an infection. Our results suggest that individuals clear or suppress infections and acquire immunity against future infections, and provide no evidence for immunosenescence nor an impact of chronic infections on survival. PMID:27431430

  7. Tracking the dynamics of the social brain: ERP approaches for social cognitive and affective neuroscience.

    PubMed

    Amodio, David M; Bartholow, Bruce D; Ito, Tiffany A

    2014-03-01

    Event-related potential (ERP) approaches to social cognitive and affective neuroscience (SCAN) are not as widely used as other neuroimaging techniques, yet they offer several unique advantages. In particular, the high temporal resolution of ERP measures of neural activity make them ideally suited for studying the dynamic interplay of rapidly unfolding cognitive and affective processes. In this article, we highlight the utility of ERP methods for scientists investigating questions of SCAN. We begin with a brief description of the physiological basis of ERPs and discussion of methodological practices. We then discuss how ERPs may be used to address a range of questions concerning social perception, social cognition, attitudes, affect and self-regulation, with examples of research that has used the ERP approach to contribute important theoretical advances in these areas. Whether used alone or in combination with other techniques, the ERP is an indispensable part of the social and affective neuroscientist's methodological toolkit.

  8. Tracking the dynamics of the social brain: ERP approaches for social cognitive and affective neuroscience

    PubMed Central

    Amodio, David M.; Ito, Tiffany A.

    2014-01-01

    Event-related potential (ERP) approaches to social cognitive and affective neuroscience (SCAN) are not as widely used as other neuroimaging techniques, yet they offer several unique advantages. In particular, the high temporal resolution of ERP measures of neural activity make them ideally suited for studying the dynamic interplay of rapidly unfolding cognitive and affective processes. In this article, we highlight the utility of ERP methods for scientists investigating questions of SCAN. We begin with a brief description of the physiological basis of ERPs and discussion of methodological practices. We then discuss how ERPs may be used to address a range of questions concerning social perception, social cognition, attitudes, affect and self-regulation, with examples of research that has used the ERP approach to contribute important theoretical advances in these areas. Whether used alone or in combination with other techniques, the ERP is an indispensable part of the social and affective neuroscientist’s methodological toolkit. PMID:24319116

  9. Infection dynamics of two renal myxozoans in hatchery reared fry and juvenile Atlantic cod Gadus morhua L.

    PubMed

    Holzer, A S; Stewart, S; Tildesley, A; Wootten, R; Sommerville, C

    2010-09-01

    In order to study the infection dynamics of 2 renal myxozoans, Zschokkella hildae Auerbach, 1910 and Gadimyxa atlantica Køie, Karlsbakk and Nylund, 2007 in cultured Atlantic cod, Gadus morhua L. aged 3-19 months, a specific single-round PCR assay and a double-label in situ hybridization protocol were developed. The results demonstrated that the 2 myxozoans show spatial separation of their development with regard to spore formation inside the renal tubules versus the collecting ducts and ureters, as well as temporal separation with Z. hildae proliferating and developing spores only once the G. atlantica infection decreases, despite the presence of both myxozoans in the smallest fry studied. These results strongly suggest within-host competition of the 2 myxozoans with potential suppression of Z. hildae by G. atlantica until G. morhua acquires immunity against G. atlantica. The quantification of the G. atlantica infection inside the renal tubules before and after a 29-day experimental growth performance study using fry from hatcheries with differing filtration systems showed that the intensity of infection with G. atlantica seems to be controlled if prolonged exposure to the myxozoan transmission stages takes place from hatching onwards. Surprisingly, growth rates in the trial were inversely affected suggesting that G. atlantica does not negatively influence cod fry growth performance.

  10. Susceptible-infected-recovered epidemics in dynamic contact networks.

    PubMed

    Volz, Erik; Meyers, Lauren Ancel

    2007-12-01

    Contact patterns in populations fundamentally influence the spread of infectious diseases. Current mathematical methods for epidemiological forecasting on networks largely assume that contacts between individuals are fixed, at least for the duration of an outbreak. In reality, contact patterns may be quite fluid, with individuals frequently making and breaking social or sexual relationships. Here, we develop a mathematical approach to predicting disease transmission on dynamic networks in which each individual has a characteristic behaviour (typical contact number), but the identities of their contacts change in time. We show that dynamic contact patterns shape epidemiological dynamics in ways that cannot be adequately captured in static network models or mass-action models. Our new model interpolates smoothly between static network models and mass-action models using a mixing parameter, thereby providing a bridge between disparate classes of epidemiological models. Using epidemiological and sexual contact data from an Atlanta high school, we demonstrate the application of this method for forecasting and controlling sexually transmitted disease outbreaks. PMID:17878137

  11. Investigation of dynamic noise affecting geodynamics information in a tethered subsatellite

    NASA Technical Reports Server (NTRS)

    Gullahorn, G. E.

    1985-01-01

    Work performed as part of an investigation of noise affecting instrumentation in a tethered subsatellite, was studied. The following specific topics were addressed during the reporting period: a method for stabilizing the subsatellite against the rotational effects of atmospheric perturbation was developed; a variety of analytic studies of tether dynamics aimed at elucidating dynamic noise processes were performed; a novel mechanism for coupling longitudinal and latitudinal oscillations of the tether was discovered, and random vibration analysis for modeling the tethered subsatellite under atmospheric perturbation were studied.

  12. Water Collective Dynamics in Whole Photosynthetic Green Algae as Affected by Protein Single Mutation.

    PubMed

    Russo, Daniela; Rea, Giuseppina; Lambreva, Maya D; Haertlein, Michael; Moulin, Martine; De Francesco, Alessio; Campi, Gaetano

    2016-07-01

    In the context of the importance of water molecules for protein function/dynamics relationship, the role of water collective dynamics in Chlamydomonas green algae carrying both native and mutated photosynthetic proteins has been investigated by neutron Brillouin scattering spectroscopy. Results show that single point genetic mutation may notably affect collective density fluctuations in hydrating water providing important insight on the transmission of information possibly correlated to biological functionality. In particular, we highlight that the damping factor of the excitations is larger in the native compared to the mutant algae as a signature of a different plasticity and structure of the hydrogen bond network. PMID:27300078

  13. Monitoring of in vitro dynamics of Acanthamoeba strains isolated from infected eyes as a useful tool in keratitis management.

    PubMed

    Chomicz, Lidia; Padzik, Marcin; Szaflik, Jacek P; Nahorski, Wacław L; Kryczka, Tomasz; Szaflik, Jerzy

    2014-11-01

    Free-living amoebae of Acanthamoeba genus are ubiquitous in various parts of the world. Some species of these amoebozoans present a serious risk to human health as the causative agents of vision-threatening diseases, Acanthamoeba keratitis. Correct diagnosis requires both a clinical examination of the cornea and amoebic form identification in affected eyes. Despite advances in pharmacotherapy, the infection is difficult to diagnose and to threat. Population dynamics of five different Acanthamoeba strains cultured in vitro under bacteria-free condition in BSC medium, was monitored in terms of diagnostic and therapeutic management. The range of protozoan number in the exponential growth phase, the morpho-physiological status of amoeba forms and their ability to multiply were evaluated. Results of the studies revealed that early and continued monitoring of the strains maintained in an axenic culture showed correlation between the dynamics of cultivated amoebae and the course of the disease, differences in response to pharmacotherapy and the surgical management efficacy. Concluding, the in vitro monitoring of dynamics of Acanthamoeba strains isolated from infected corneas may be important not only for proper diagnosis but also as a useful tool in keratitis management and therapeutic prognosis.

  14. Myenteric plexus is differentially affected by infection with distinct Trypanosoma cruzi strains in Beagle dogs

    PubMed Central

    Nogueira-Paiva, Nívia Carolina; Fonseca, Kátia da Silva; Vieira, Paula Melo de Abreu; Diniz, Lívia Figueiredo; Caldas, Ivo Santana; de Moura, Sandra Aparecida Lima; Veloso, Vanja Maria; Guedes, Paulo Marcos da Matta; Tafuri, Washington Luiz; Bahia, Maria Terezinha; Carneiro, Cláudia Martins

    2013-01-01

    Chagasic megaoesophagus and megacolon are characterised by motor abnormalities related to enteric nervous system lesions and their development seems to be related to geographic distribution of distinct Trypanosoma cruzi subpopulations. Beagle dogs were infected with Y or Berenice-78 (Be-78) T. cruzi strains and necropsied during the acute or chronic phase of experimental disease for post mortem histopathological evaluation of the oesophagus and colon. Both strains infected the oesophagus and colon and caused an inflammatory response during the acute phase. In the chronic phase, inflammatory process was observed exclusively in the Be-78 infected animals, possibly due to a parasitism persistent only in this group. Myenteric denervation occurred during the acute phase of infection for both strains, but persisted chronically only in Be-78 infected animals. Glial cell involvement occurred earlier in animals infected with the Y strain, while animals infected with the Be-78 strain showed reduced glial fibrillary acidic protein immunoreactive area of enteric glial cells in the chronic phase. These results suggest that although both strains cause lesions in the digestive tract, the Y strain is associated with early control of the lesion, while the Be-78 strain results in progressive gut lesions in this model. PMID:24271001

  15. Genotypic variation in host response to infection affects parasite reproductive rate.

    PubMed

    Tavalire, Hannah F; Blouin, Michael S; Steinauer, Michelle L

    2016-02-01

    Parasite fitness is largely influenced by a variation in host response due to the host's genetic background. Here we investigated the impact of host genotype on pathogen success in the snail vector of its castrating parasite, Schistosoma mansoni. We infected five inbred lines of Biomphalaria glabrata with two infection doses and followed their growth, reproductive output and parasite production throughout the course of infection. There was no difference in resistance to infection among inbred lines, but lines varied in their responses to infection and the numbers of parasites produced. Snails did not compensate for castration by increasing their fecundity during the early phase of infection (fecundity compensation). However, some lines were able to delay parasite shedding for up to 30 weeks, thus prolonging reproduction before the onset of castration. Here we propose this strategy as a novel defense against castrating pathogens in snails. Gigantism, a predicted outcome of castration due to energy reallocation, occurred early in infection (<15 weeks) and was not universal among the snail lines. Lines that did not show gigantism were also characterised by a high parasite production rate and low survivorship, perhaps indicating energy reallocation into parasite production and costly immune defense. We observed no differences in total parasite production among lines throughout the entire course of infection, although lines differed in their parasite reproductive rate. The average rate of parasite production varied among lines from 1300 to 2450 cercariae within a single 2h shedding period, resulting in a total production of 6981-29,509 cercariae over the lifetime of a single snail. Regardless of genetic background, snail size was a strong predictor of parasite reproduction: each millimetre increase in snail size at the time of the first shed resulted in up to 3500 more cercariae over the lifetime of the snail. The results of this study provide a detailed picture of

  16. Genotypic variation in host response to infection affects parasite reproductive rate.

    PubMed

    Tavalire, Hannah F; Blouin, Michael S; Steinauer, Michelle L

    2016-02-01

    Parasite fitness is largely influenced by a variation in host response due to the host's genetic background. Here we investigated the impact of host genotype on pathogen success in the snail vector of its castrating parasite, Schistosoma mansoni. We infected five inbred lines of Biomphalaria glabrata with two infection doses and followed their growth, reproductive output and parasite production throughout the course of infection. There was no difference in resistance to infection among inbred lines, but lines varied in their responses to infection and the numbers of parasites produced. Snails did not compensate for castration by increasing their fecundity during the early phase of infection (fecundity compensation). However, some lines were able to delay parasite shedding for up to 30 weeks, thus prolonging reproduction before the onset of castration. Here we propose this strategy as a novel defense against castrating pathogens in snails. Gigantism, a predicted outcome of castration due to energy reallocation, occurred early in infection (<15 weeks) and was not universal among the snail lines. Lines that did not show gigantism were also characterised by a high parasite production rate and low survivorship, perhaps indicating energy reallocation into parasite production and costly immune defense. We observed no differences in total parasite production among lines throughout the entire course of infection, although lines differed in their parasite reproductive rate. The average rate of parasite production varied among lines from 1300 to 2450 cercariae within a single 2h shedding period, resulting in a total production of 6981-29,509 cercariae over the lifetime of a single snail. Regardless of genetic background, snail size was a strong predictor of parasite reproduction: each millimetre increase in snail size at the time of the first shed resulted in up to 3500 more cercariae over the lifetime of the snail. The results of this study provide a detailed picture of

  17. Host and parasite genetics shape a link between Trypanosoma cruzi infection dynamics and chronic cardiomyopathy.

    PubMed

    Lewis, Michael D; Francisco, Amanda Fortes; Taylor, Martin C; Jayawardhana, Shiromani; Kelly, John M

    2016-10-01

    Host and parasite diversity are suspected to be key factors in Chagas disease pathogenesis. Experimental investigation of underlying mechanisms is hampered by a lack of tools to detect scarce, pleiotropic infection foci. We developed sensitive imaging models to track Trypanosoma cruzi infection dynamics and quantify tissue-specific parasite loads, with minimal sampling bias. We used this technology to investigate cardiomyopathy caused by highly divergent parasite strains in BALB/c, C3H/HeN and C57BL/6 mice. The gastrointestinal tract was unexpectedly found to be the primary site of chronic infection in all models. Immunosuppression induced expansion of parasite loads in the gut and was followed by widespread dissemination. These data indicate that differential immune control of T. cruzi occurs between tissues and shows that the large intestine and stomach provide permissive niches for active infection. The end-point frequency of heart-specific infections ranged from 0% in TcVI-CLBR-infected C57BL/6 to 88% in TcI-JR-infected C3H/HeN mice. Nevertheless, infection led to fibrotic cardiac pathology in all models. Heart disease severity was associated with the model-dependent frequency of dissemination outside the gut and inferred cumulative heart-specific parasite loads. We propose a model of cardiac pathogenesis driven by periodic trafficking of parasites into the heart, occurring at a frequency determined by host and parasite genetics.

  18. The effects of exposure to dynamic expressions of affect on 5-month-olds' memory.

    PubMed

    Flom, Ross; Janis, Rebecca B; Garcia, Darren J; Kirwan, C Brock

    2014-11-01

    The purpose of this study was to examine the behavioral effects of adults' communicated affect on 5-month-olds' visual recognition memory. Five-month-olds were exposed to a dynamic and bimodal happy, angry, or neutral affective (face-voice) expression while familiarized to a novel geometric image. After familiarization to the geometric image and exposure to the affective expression, 5-month-olds received either a 5-min or 1-day retention interval. Following the 5-min retention interval, infants exposed to the happy affective expressions showed a reliable preference for a novel geometric image compared to the recently familiarized image. Infants exposed to the neutral or angry affective expression failed to show a reliable preference following a 5-min delay. Following the 1-day retention interval, however, infants exposed to the neutral expression showed a reliable preference for the novel geometric image. These results are the first to demonstrate that 5-month-olds' visual recognition memory is affected by the presentation of affective information at the time of encoding.

  19. Rhizobium Infection and Nodule Development in Soybean Are Affected by Exposure of the Cotyledons to Light 1

    PubMed Central

    Malik, Nasir S. A.; Pence, Mark K.; Calvert, Harry E.; Bauer, Wolfgang D.

    1984-01-01

    The initiation of Rhizobium infections and the development of nodules on the primary root of soybean Glycine max L. Merr cv Williams seedlings are strongly affected by exposure of the cotyledons/hypocotyls to light. Seedlings in plastic growth pouches were inoculated with R. japonicum in dim light and the position of the root tip of each seedling was marked on the face of the pouch. The pouches were covered and kept in the dark for various times before exposing the upper portions of the plants (cotyledons and hypocotyls) to light. Maximum nodulation occurred if the plants were kept in the dark until 1 day after inoculation. The exposure of plants to light 2 days before inoculation reduced the number of nodules by 50% while the number of nodules was reduced by 70% if the plants were kept in the dark until 7 days after inoculation. Anatomical studies revealed that exposure to light prior to inoculation reduced both the number of infection centers with visible infection threads and the number of infections which developed nodule meristems. Plants kept in the dark for 7 days after inoculation formed a normal number of infection threads above the root tip mark, but very few of these infections developed a nodule meristem. It appears that light stimulates soybean to produce substances which can both inhibit the formation of infection threads and enhance the development of nodules from established infection threads. The effects of light on nodulation appear to be expressed independently of the Rhizobium-induced suppression of nodule formation in younger regions of the root. PMID:16663609

  20. Dynamics of the HIV infection under antiretroviral therapy: A cellular automata approach

    NASA Astrophysics Data System (ADS)

    González, Ramón E. R.; Coutinho, Sérgio; Zorzenon dos Santos, Rita Maria; de Figueirêdo, Pedro Hugo

    2013-10-01

    The dynamics of human immunodeficiency virus infection under antiretroviral therapy is investigated using a cellular automata model where the effectiveness of each drug is self-adjusted by the concentration of CD4+ T infected cells present at each time step. The effectiveness of the drugs and the infected cell concentration at the beginning of treatment are the control parameters of the cell population’s dynamics during therapy. The model allows describing processes of mono and combined therapies. The dynamics that emerges from this model when considering combined antiretroviral therapies reproduces with fair qualitative agreement the phases and different time scales of the process. As observed in clinical data, the results reproduce the significant decrease in the population of infected cells and a concomitant increase of the population of healthy cells in a short timescale (weeks) after the initiation of treatment. Over long time scales, early treatment with potent drugs may lead to undetectable levels of infection. For late treatment or treatments starting with a low density of CD4+ T healthy cells it was observed that the treatment may lead to a steady state in which the T cell counts are above the threshold associated with the onset of AIDS. The results obtained are validated through comparison to available clinical trial data.

  1. Measles on the edge: coastal heterogeneities and infection dynamics.

    PubMed

    Bharti, Nita; Xia, Yingcun; Bjornstad, Ottar N; Grenfell, Bryan T

    2008-01-01

    Mathematical models can help elucidate the spatio-temporal dynamics of epidemics as well as the impact of control measures. The gravity model for directly transmitted diseases is currently one of the most parsimonious models for spatial epidemic spread. This model uses distance-weighted, population size-dependent coupling to estimate host movement and disease incidence in metapopulations. The model captures overall measles dynamics in terms of underlying human movement in pre-vaccination England and Wales (previously established). In spatial models, edges often present a special challenge. Therefore, to test the model's robustness, we analyzed gravity model incidence predictions for coastal cities in England and Wales. Results show that, although predictions are accurate for inland towns, they significantly underestimate coastal persistence. We examine incidence, outbreak seasonality, and public transportation records, to show that the model's inaccuracies stem from an underestimation of total contacts per individual along the coast. We rescue this predicted 'edge effect' by increasing coastal contacts to approximate the number of per capita inland contacts. These results illustrate the impact of 'edge effects' on epidemic metapopulations in general and illustrate directions for the refinement of spatiotemporal epidemic models. PMID:18398467

  2. Dynamics of Dual Infection with Campylobacter jejuni Strains in Chickens Reveals Distinct Strain-to-Strain Variation in Infection Ecology

    PubMed Central

    Wigley, Paul; Humphrey, Suzanne; Kemmett, Kirsty; Lacharme-Lora, Lizeth; Humphrey, Tom; Williams, Nicola

    2014-01-01

    Although multiple genotypes of Campylobacter jejuni may be isolated from the same commercial broiler flock, little is known about the infection dynamics of different genotypes within individuals or their colonization sites within the gut. Single experimental infections with C. jejuni M1 (sequence type 137, clonal complex 45) and C. jejuni 13126 (sequence type 21, clonal complex 21) revealed that 13126 colonized the ceca at significantly higher levels. The dissemination and colonization sites of the two C. jejuni strains then were examined in an experimental broiler flock. Two 33-day-old broiler chickens were infected with M1 and two with 13126, and 15 birds were left unchallenged. Cloacal swabs were taken postinfection to determine the colonization and shedding of each strain. By 2 days postinfection (dpi), 8/19 birds were shedding M1 whereas none were shedding 13126. At 8 dpi, all birds were shedding both strains. At 18 dpi, liver and cecal levels of each isolate were quantified, while in 10 birds they also were quantified at nine sites throughout the gastrointestinal (GI) tract. 13126 was found throughout the GI tract, while M1 was largely restricted to the ceca and colon. The livers of 7/19 birds were culture positive for 13126 only. These data show that 13126 has a distinctly different infection biology than strain M1. It showed slower colonization of the lower GI tract but was more invasive and able to colonize at a high level throughout the GI tract. The finding that C. jejuni strains have markedly different infection ecologies within the chicken has implications for control in the poultry industry and suggests that the contamination risk of edible tissues is dependent on the isolate involved. PMID:25107966

  3. Temporal dynamics of Puumala hantavirus infection in cyclic populations of bank voles

    PubMed Central

    Voutilainen, Liina; Kallio, Eva R.; Niemimaa, Jukka; Vapalahti, Olli; Henttonen, Heikki

    2016-01-01

    Understanding the dynamics of zoonotic pathogens in their reservoir host populations is a prerequisite for predicting and preventing human disease epidemics. The human infection risk of Puumala hantavirus (PUUV) is highest in northern Europe, where populations of the rodent host (bank vole, Myodes glareolus) undergo cyclic fluctuations. We conducted a 7-year capture-mark-recapture study to monitor seasonal and multiannual patterns of the PUUV infection rate in bank vole populations exhibiting a 3-year density cycle. Infected bank voles were most abundant in mid-winter months during years of increasing or peak host density. Prevalence of PUUV infection in bank voles exhibited a regular, seasonal pattern reflecting the annual population turnover and accumulation of infections within each year cohort. In autumn, the PUUV transmission rate tracked increasing host abundance, suggesting a density-dependent transmission. However, prevalence of PUUV infection was similar during the increase and peak years of the density cycle despite a twofold difference in host density. This may result from the high proportion of individuals carrying maternal antibodies constraining transmission during the cycle peak years. Our exceptionally intensive and long-term dataset provides a solid basis on which to develop models to predict the dynamic public health threat posed by PUUV in northern Europe. PMID:26887639

  4. Temporal dynamics of Puumala hantavirus infection in cyclic populations of bank voles.

    PubMed

    Voutilainen, Liina; Kallio, Eva R; Niemimaa, Jukka; Vapalahti, Olli; Henttonen, Heikki

    2016-01-01

    Understanding the dynamics of zoonotic pathogens in their reservoir host populations is a prerequisite for predicting and preventing human disease epidemics. The human infection risk of Puumala hantavirus (PUUV) is highest in northern Europe, where populations of the rodent host (bank vole, Myodes glareolus) undergo cyclic fluctuations. We conducted a 7-year capture-mark-recapture study to monitor seasonal and multiannual patterns of the PUUV infection rate in bank vole populations exhibiting a 3-year density cycle. Infected bank voles were most abundant in mid-winter months during years of increasing or peak host density. Prevalence of PUUV infection in bank voles exhibited a regular, seasonal pattern reflecting the annual population turnover and accumulation of infections within each year cohort. In autumn, the PUUV transmission rate tracked increasing host abundance, suggesting a density-dependent transmission. However, prevalence of PUUV infection was similar during the increase and peak years of the density cycle despite a twofold difference in host density. This may result from the high proportion of individuals carrying maternal antibodies constraining transmission during the cycle peak years. Our exceptionally intensive and long-term dataset provides a solid basis on which to develop models to predict the dynamic public health threat posed by PUUV in northern Europe. PMID:26887639

  5. Determination of original infection source of H7N9 avian influenza by dynamical model.

    PubMed

    Zhang, Juan; Jin, Zhen; Sun, Gui-Quan; Sun, Xiang-Dong; Wang, You-Ming; Huang, Baoxu

    2014-01-01

    H7N9, a newly emerging virus in China, travels among poultry and human. Although H7N9 has not aroused massive outbreaks, recurrence in the second half of 2013 makes it essential to control the spread. It is believed that the most effective control measure is to locate the original infection source and cut off the source of infection from human. However, the original infection source and the internal transmission mechanism of the new virus are not totally clear. In order to determine the original infection source of H7N9, we establish a dynamical model with migratory bird, resident bird, domestic poultry and human population, and view migratory bird, resident bird, domestic poultry as original infection source respectively to fit the true dynamics during the 2013 pandemic. By comparing the date fitting results and corresponding Akaike Information Criterion (AIC) values, we conclude that migrant birds are most likely the original infection source. In addition, we obtain the basic reproduction number in poultry and carry out sensitivity analysis of some parameters. PMID:24786135

  6. Determination of Original Infection Source of H7N9 Avian Influenza by Dynamical Model

    NASA Astrophysics Data System (ADS)

    Zhang, Juan; Jin, Zhen; Sun, Gui-Quan; Sun, Xiang-Dong; Wang, You-Ming; Huang, Baoxu

    2014-05-01

    H7N9, a newly emerging virus in China, travels among poultry and human. Although H7N9 has not aroused massive outbreaks, recurrence in the second half of 2013 makes it essential to control the spread. It is believed that the most effective control measure is to locate the original infection source and cut off the source of infection from human. However, the original infection source and the internal transmission mechanism of the new virus are not totally clear. In order to determine the original infection source of H7N9, we establish a dynamical model with migratory bird, resident bird, domestic poultry and human population, and view migratory bird, resident bird, domestic poultry as original infection source respectively to fit the true dynamics during the 2013 pandemic. By comparing the date fitting results and corresponding Akaike Information Criterion (AIC) values, we conclude that migrant birds are most likely the original infection source. In addition, we obtain the basic reproduction number in poultry and carry out sensitivity analysis of some parameters.

  7. The Dynamics of HCF-1 Modulation of Herpes Simplex Virus Chromatin during Initiation of Infection

    PubMed Central

    Vogel, Jodi L.; Kristie, Thomas M.

    2013-01-01

    Successful infection of herpes simplex virus is dependent upon chromatin modulation by the cellular coactivator host cell factor-1 (HCF-1). This review focuses on the multiple chromatin modulation components associated with HCF-1 and the chromatin-related dynamics mediated by this coactivator that lead to the initiation of herpes simplex virus (HSV) immediate early gene expression. PMID:23698399

  8. Herpesvirus infection with severe lymphoid necrosis affecting a beaked whale stranded in the Canary Islands.

    PubMed

    Arbelo, Manuel; Sierra, Eva; Esperón, Fernando; Watanabe, Tatiane T N; Bellière, Edwige N; Espinosa de los Monteros, Antonio; Fernández, Antonio

    2010-04-01

    This report describes the pathologic findings in a single, adult female Cuvier's beaked whale Ziphius cavirostris stranded in the Canary Islands. The study indicated that this whale died with a severe, systemic, herpesviral infection and clearly exhibited lesions different from those of the fat and gas embolic syndrome described in beaked whale mass strandings associated with sonar exposure. This is the first report of a cetacean alphaherpesvirus infection of the lymphoid system in a beaked whale.

  9. Chronic HCV Infection Affects the NK Cell Phenotype in the Blood More than in the Liver

    PubMed Central

    Kroy, Daniela C.; Cheney, Patrick C.; Ghebremichael, Musie; Aneja, Jasneet; Tomlinson, Michelle; Kim, Arthur Y.; Lauer, Georg M.; Alter, Galit

    2014-01-01

    Although epidemiological and functional studies have implicated NK cells in protection and early clearance of HCV, the mechanism by which they may contribute to viral control is poorly understood, particularly at the site of infection, the liver. We hypothesized that a unique immunophenotypic/functional NK cell signature exists in the liver that may provide insights into the contribution of NK cells to viral control. Intrahepatic and blood NK cells were profiled from chronically infected HCV-positive and HCV-negative individuals. Baseline expression of activating and inhibitory receptors was assessed, as well as functional responses following stimulation through classic NK cell pathways. Independent of HCV infection, the liver was enriched for the immunoregulatory CD56bright NK cell population, which produced less IFNγ and CD107a but comparable levels of MIP1β, and was immunophenotypically distinct from their blood counterparts. This profile was mostly unaltered in chronic HCV infection, though different expression levels of NKp46 and NKG2D were associated with different grades of fibrosis. In contrast to the liver, chronic HCV infection associated with an enrichment of CD161lowperforinhigh NK cells in the blood correlated with increased AST and 2B4 expression. However, the association of relatively discrete changes in the NK cell phenotype in the liver with the fibrosis stage nevertheless suggests an important role for the NK response. Overall these data suggest that tissue localization has a more pervasive effect on NK cells than the presence of chronic viral infection, during which these cells might be mostly attuned to limiting immunopathology. It will be important to characterize NK cells during early HCV infection, when they should have a critical role in limiting infection. PMID:25148254

  10. Rootstock-scion interaction affecting citrus response to CTV infection: a proteomic view.

    PubMed

    Laino, Paolo; Russo, Maria P; Guardo, Maria; Reforgiato-Recupero, Giuseppe; Valè, Giampiero; Cattivelli, Luigi; Moliterni, Vita M C

    2016-04-01

    Citrus tristeza virus (CTV) is the causal agent of various diseases with dramatic effects on citrus crops worldwide. Most Citrus species, grown on their own roots, are symptomless hosts for many CTV isolates. However, depending on different scion-rootstock combination, CTV infection should result in distinct syndromes, being 'tristeza' the more severe one, leading to a complete decline of the susceptible plants in a few weeks. Transcriptomic analyses revealed several genes involved either in defense response, or systemic acquired resistance, as well as transcription factors and components of the phosphorylation cascades, to be differentially regulated during CTV infection in Citrus aurantifolia species. To date little is known about the molecular mechanism of this host-pathogen interaction, and about the rootstock effect on citrus response to CTV infection. In this work, the response to CTV infection has been investigated in tolerant and susceptible scion-rootstock combinations by two-dimensional gel electrophoresis (2DE). A total of 125 protein spots have been found to be differently accumulated and/or phosphorylated between the two rootstock combinations. Downregulation in tolerant plants upon CTV infection was detected for proteins involved in reactive oxygen species (ROS) scavenging and defense response, suggesting a probable acclimation response able to minimize the systemic effects of virus infection. Some of these proteins resulted to be modulated also in absence of virus infection, revealing a rootstock effect on scion proteome modulation. Moreover, the phospho-modulation of proteins involved in ROS scavenging and defense response, further supports their involvement either in scion-rootstock crosstalk or in the establishment of tolerance/susceptibility to CTV infection. PMID:26459956

  11. Factors Affecting Phage D29 Infection: A Tool to Investigate Different Growth States of Mycobacteria

    PubMed Central

    Swift, Benjamin M. C.; Gerrard, Zara E.; Huxley, Jonathan N.; Rees, Catherine E. D.

    2014-01-01

    Bacteriophages D29 and TM4 are able to infect a wide range of mycobacteria, including pathogenic and non-pathogenic species. Successful phage infection of both fast- and slow-growing mycobacteria can be rapidly detected using the phage amplification assay. Using this method, the effect of oxygen limitation during culture of mycobacteria on the success of phage infection was studied. Both D29 and TM4 were able to infect cultures of M. smegmatis and Mycobacterium avium subspecies paratuberculosis (MAP) grown in liquid with aeration. However when cultures were grown under oxygen limiting conditions, only TM4 could productively infect the cells. Cell attachment assays showed that D29 could bind to the cells surface but did not complete the lytic cycle. The ability of D29 to productively infect the cells was rapidly recovered (within 1 day) when the cultures were returned to an aerobic environment and this recovery required de novo RNA synthesis. These results indicated that under oxygen limiting conditions the cells are entering a growth state which inhibits phage D29 replication, and this change in host cell biology which can be detected by using both phage D29 and TM4 in the phage amplification assay. PMID:25184428

  12. Affective disorders as complex dynamic diseases--a perspective from systems biology.

    PubMed

    Tretter, F; Gebicke-Haerter, P J; an der Heiden, U; Rujescu, D; Mewes, H W; Turck, C W

    2011-05-01

    Understanding mental disorders and their neurobiological basis encompasses the conceptual management of "complexity" and "dynamics". For example, affective disorders exhibit several fluctuating state variables on psychological and biological levels and data collected of these systems levels suggest quasi-chaotic periodicity leading to use concepts and tools of the mathematics of nonlinear dynamic systems. Regarding this, we demonstrate that the concept of "Dynamic Diseases" could be a fruitful way for theory and empirical research in neuropsychiatry. In a first step, as an example, we focus on the analysis of dynamic cortisol regulation that is important for understanding depressive disorders. In this case, our message is that extremely complex phenomena of a disease may be explained as resulting from perplexingly simple nonlinear interactions of a very small number of variables. Additionally, we propose that and how widely used complex circuit diagrams representing the macroanatomic structures and connectivities of the brain involved in major depression or other mental disorders may be "animated" by quantification, even by using expert-based estimations (dummy variables). This method of modeling allows to develop exploratory computer-based numerical models that encompass the option to explore the system by computer simulations (in-silico experiments). Also inter- and intracellular molecular networks involved in affective disorders could be modeled by this procedure. We want to stimulate future research in this theoretical context. PMID:21544742

  13. Stochastic disease dynamics of a hospital infection model.

    PubMed

    Wang, Xia; Xiao, Yanni; Wang, Junrui; Lu, Xinxin

    2013-01-01

    A stochastic model for hospital infection incorporating both direct transmission and indirect transmission via free-living bacteria in the environment is investigated. We examine the long term behavior of the model by calculating a stationary distribution and normal approximation of the distribution. The quasi-stationary distribution of the model is studied to investigate the models' behavior before extinction and the time to extinction. Numerical results show agreement between the calculated distributions and results of event-driven simulations. Hand hygiene of volunteers is more effective in terms of reducing the mean (or standard deviation) of the stationary distribution of colonized patients and the expected time to extinction compared to hand hygiene of health care workers (HCWs), on the basis of our parameter values. However, the indirect (or direct) transmission rate can lead to either increase or decrease in the standard deviation of the stationary distribution, but the impact of the indirect transmission is much greater than that of the direct transmission. The findings suggest that isolation of new admitted colonized patients is most effective in reducing both the mean and standard deviation of the stationary distribution and measures related to indirect transmission are secondary in their effects compared to other interventions. PMID:23103300

  14. HTLV-I infection: a dynamic struggle between viral persistence and host immunity.

    PubMed

    Lim, Aaron G; Maini, Philip K

    2014-07-01

    Human T-lymphotropic virus type I (HTLV-I) causes chronic infection for which there is no cure or neutralising vaccine. HTLV-I has been clinically linked to the development of adult T-cell leukaemia/lymphoma (ATL), an aggressive blood cancer, and HAM/TSP, a progressive neurological and inflammatory disease. Infected individuals typically mount a large, persistently activated CD8(+) cytotoxic T-lymphocyte (CTL) response against HTLV-I-infected cells, but ultimately fail to effectively eliminate the virus. Moreover, the identification of determinants to disease manifestation has thus far been elusive. A key issue in current HTLV-I research is to better understand the dynamic interaction between persistent infection by HTLV-I and virus-specific host immunity. Recent experimental hypotheses for the persistence of HTLV-I in vivo have led to the development of mathematical models illuminating the balance between proviral latency and activation in the target cell population. We investigate the role of a constantly changing anti-viral immune environment acting in response to the effects of infected T-cell activation and subsequent viral expression. The resulting model is a four-dimensional, non-linear system of ordinary differential equations that describes the dynamic interactions among viral expression, infected target cell activation, and the HTLV-I-specific CTL response. The global dynamics of the model is established through the construction of appropriate Lyapunov functions. Examining the particular roles of viral expression and host immunity during the chronic phase of HTLV-I infection offers important insights regarding the evolution of viral persistence and proposes a hypothesis for pathogenesis. PMID:24583256

  15. Amino acid changes within the E protein hinge region that affect dengue virus type 2 infectivity and fusion

    SciTech Connect

    Butrapet, Siritorn; Childers, Thomas; Moss, Kelley J.; Erb, Steven M.; Luy, Betty E.; Calvert, Amanda E.; Blair, Carol D.; Roehrig, John T.; Huang, Claire Y.-H.

    2011-04-25

    Fifteen mutant dengue viruses were engineered and used to identify AAs in the molecular hinge of the envelope protein that are critical to viral infection. Substitutions at Q52, A54, or E133 reduced infectivity in mammalian cells and altered the pH threshold of fusion. Mutations at F193, G266, I270, or G281 affected viral replication in mammalian and mosquito cells, but only I270W had reduced fusion activity. T280Y affected the pH threshold for fusion and reduced replication in C6/36 cells. Three different mutations at L135 were lethal in mammalian cells. Among them, L135G abrogated fusion and reduced replication in C6/36 cells, but only slightly reduced the mosquito infection rate. Conversely, L135W replicated well in C6/36 cells, but had the lowest mosquito infection rate. Possible interactions between hinge residues 52 and 277, or among 53, 135, 170, 186, 265, and 276 required for hinge function were discovered by sequence analysis to identify compensatory mutations.

  16. Rhythm is it: effects of dynamic body feedback on affect and attitudes

    PubMed Central

    Koch, Sabine C.

    2014-01-01

    Body feedback is the proprioceptive feedback that denominates the afferent information from position and movement of the body to the central nervous system. It is crucial in experiencing emotions, in forming attitudes and in regulating emotions and behavior. This paper investigates effects of dynamic body feedback on affect and attitudes, focusing on the impact of movement rhythms with smooth vs. sharp reversals as one basic category of movement qualities. It relates those qualities to already explored effects of approach vs. avoidance motor behavior as one basic category of movement shape. Studies 1 and 2 tested the effects of one of two basic movement qualities (smooth vs. sharp rhythms) on affect and cognition. The third study tested those movement qualities in combination with movement shape (approach vs. avoidance motor behavior) and the effects of those combinations on affect and attitudes toward initially valence-free stimuli. Results suggest that movement rhythms influence affect (studies 1 and 2), and attitudes (study 3), and moderate the impact of approach and avoidance motor behavior on attitudes (study 3). Extending static body feedback research with a dynamic account, findings indicate that movement qualities – next to movement shape – play an important role, when movement of the lived body is an independent variable. PMID:24959153

  17. Solving the Dynamic Correlation Problem of the Susceptible-Infected-Susceptible Model on Networks.

    PubMed

    Cai, Chao-Ran; Wu, Zhi-Xi; Chen, Michael Z Q; Holme, Petter; Guan, Jian-Yue

    2016-06-24

    The susceptible-infected-susceptible (SIS) model is a canonical model for emerging disease outbreaks. Such outbreaks are naturally modeled as taking place on networks. A theoretical challenge in network epidemiology is the dynamic correlations coming from that if one node is infected, then its neighbors are likely to be infected. By combining two theoretical approaches-the heterogeneous mean-field theory and the effective degree method-we are able to include these correlations in an analytical solution of the SIS model. We derive accurate expressions for the average prevalence (fraction of infected) and epidemic threshold. We also discuss how to generalize the approach to a larger class of stochastic population models.

  18. Solving the Dynamic Correlation Problem of the Susceptible-Infected-Susceptible Model on Networks

    NASA Astrophysics Data System (ADS)

    Cai, Chao-Ran; Wu, Zhi-Xi; Chen, Michael Z. Q.; Holme, Petter; Guan, Jian-Yue

    2016-06-01

    The susceptible-infected-susceptible (SIS) model is a canonical model for emerging disease outbreaks. Such outbreaks are naturally modeled as taking place on networks. A theoretical challenge in network epidemiology is the dynamic correlations coming from that if one node is infected, then its neighbors are likely to be infected. By combining two theoretical approaches—the heterogeneous mean-field theory and the effective degree method—we are able to include these correlations in an analytical solution of the SIS model. We derive accurate expressions for the average prevalence (fraction of infected) and epidemic threshold. We also discuss how to generalize the approach to a larger class of stochastic population models.

  19. Young Children’s Affective Responses to Another’s Distress: Dynamic and Physiological Features

    PubMed Central

    Fink, Elian; Heathers, James A. J.; de Rosnay, Marc

    2015-01-01

    Two descriptive studies set out a new approach for exploring the dynamic features of children’s affective responses (sadness and interest-worry) to another’s distress. In two samples (Nstudy1 = 75; Nstudy2 = 114), Kindergarten children were shown a video-vignette depicting another child in distress and the temporal pattern of spontaneous expressions were examined across the unfolding vignette. Results showed, in both study 1 and 2, that sadness and interest-worry had distinct patterns of elicitation across the events of the vignette narrative and there was little co-occurrence of these affects within a given child. Temporal heart rate changes (study 2) were closely aligned to the events of the vignette and, furthermore, affective responses corresponded to distinctive physiological response profiles. The implications of distinct temporal patterns of elicitation for the meaning of sadness and interest-worry are discussed within the framework of emotion regulation and empathy. PMID:25874952

  20. Invasion Dynamics of Teratogenic Infections in Light of Rubella Control: Implications for Zika Virus

    PubMed Central

    Metcalf, C. Jessica E.; Barrett, Alan

    2016-01-01

    Introduction: The greatest burden for a subset of pathogens is associated with infection during pregnancy. Evidence for teratogenic effects of Zika Virus have highlighted the importance of understanding the epidemiology of such pathogens. Rubella is perhaps the most classic example, and there is much to be learned from the long history of modelling associated with this virus. Methods: We extended an existing framework for modeling age-specific dynamics of rubella to illustrate how the body of knowledge of rubella dynamics informs the dynamics of teratogenic infections more broadly, and particularly the impact of control on such infections in different transmission settings. Results: During invasion, the burden in women of childbearing age is expected to peak, but then fall to low levels before eventually levelling out. Importantly, as illustrated by rubella dynamics, there is potential for a paradoxical effect, where inadequate control efforts can increase the burden. Conclusions: Drawing on the existing body of work on rubella dynamics highlights key knowledge gaps for understanding the risks associated with Zika Virus. The magnitude and impacts of sterilizing immunity, plus antigenic maps measuring cross-protection with other flaviviruses, and the magnitude of transmission, as well as likely impact of control efforts on transmission are likely to be key variables for robust inference into the outcome of management efforts for Zika Virus.

  1. Invasion Dynamics of Teratogenic Infections in Light of Rubella Control: Implications for Zika Virus

    PubMed Central

    Metcalf, C. Jessica E.; Barrett, Alan

    2016-01-01

    Introduction: The greatest burden for a subset of pathogens is associated with infection during pregnancy. Evidence for teratogenic effects of Zika Virus have highlighted the importance of understanding the epidemiology of such pathogens. Rubella is perhaps the most classic example, and there is much to be learned from the long history of modelling associated with this virus. Methods: We extended an existing framework for modeling age-specific dynamics of rubella to illustrate how the body of knowledge of rubella dynamics informs the dynamics of teratogenic infections more broadly, and particularly the impact of control on such infections in different transmission settings. Results: During invasion, the burden in women of childbearing age is expected to peak, but then fall to low levels before eventually levelling out. Importantly, as illustrated by rubella dynamics, there is potential for a paradoxical effect, where inadequate control efforts can increase the burden. Conclusions: Drawing on the existing body of work on rubella dynamics highlights key knowledge gaps for understanding the risks associated with Zika Virus. The magnitude and impacts of sterilizing immunity, plus antigenic maps measuring cross-protection with other flaviviruses, and the magnitude of transmission, as well as likely impact of control efforts on transmission are likely to be key variables for robust inference into the outcome of management efforts for Zika Virus. PMID:27617170

  2. Dynamic Immune Cell Recruitment After Murine Pulmonary Aspergillus fumigatus Infection under Different Immunosuppressive Regimens

    PubMed Central

    Kalleda, Natarajaswamy; Amich, Jorge; Arslan, Berkan; Poreddy, Spoorthi; Mattenheimer, Katharina; Mokhtari, Zeinab; Einsele, Hermann; Brock, Matthias; Heinze, Katrin Gertrud; Beilhack, Andreas

    2016-01-01

    Humans are continuously exposed to airborne spores of the saprophytic fungus Aspergillus fumigatus. However, in healthy individuals pulmonary host defense mechanisms efficiently eliminate the fungus. In contrast, A. fumigatus causes devastating infections in immunocompromised patients. Host immune responses against A. fumigatus lung infections in immunocompromised conditions have remained largely elusive. Given the dynamic changes in immune cell subsets within tissues upon immunosuppressive therapy, we dissected the spatiotemporal pulmonary immune response after A. fumigatus infection to reveal basic immunological events that fail to effectively control invasive fungal disease. In different immunocompromised murine models, myeloid, notably neutrophils, and macrophages, but not lymphoid cells were strongly recruited to the lungs upon infection. Other myeloid cells, particularly dendritic cells and monocytes, were only recruited to lungs of corticosteroid treated mice, which developed a strong pulmonary inflammation after infection. Lymphoid cells, particularly CD4+ or CD8+ T-cells and NK cells were highly reduced upon immunosuppression and not recruited after A. fumigatus infection. Moreover, adoptive CD11b+ myeloid cell transfer rescued cyclophosphamide immunosuppressed mice from lethal A. fumigatus infection but not cortisone and cyclophosphamide immunosuppressed mice. Our findings illustrate that CD11b+ myeloid cells are critical for anti-A. fumigatus defense under cyclophosphamide immunosuppressed conditions. PMID:27468286

  3. Temporal dynamics of a local fish community are strongly affected by immigration from the surrounding metacommunity

    PubMed Central

    Stoffels, Rick J; Clarke, Kenneth Robert; Linklater, Danielle S

    2015-01-01

    A 5-year time series of annual censuses was collected from a large floodplain lake to determine how dynamics of the local fish community were affected by changes in hydrological connectivity with the surrounding metacommunity. The lake was disconnected from the metacommunity for 1 year prior to our study and remained disconnected until 3 months before our third annual census, when a flood reconnected the lake to the metacommunity. We determined how changes in connectivity affected temporal dynamics of (1) local community composition and (2) the population composition, condition, and growth of catfish, to shed light on how immigration of other species might affect local population dynamics. Before reconnection, the community was likely shaped by interactions between the local environment and species traits. The reconnection caused significant immigration and change in community composition and correlated with a significant and abrupt decline in catfish condition, growth, and abundance; effects likely due to the immigration of a competitor with a similar trophic niche: carp. The community was slow to return to its preconnection state, which may be due to dispersal traits of the fishes, and a time-lag in the recovery of the local catfish population following transient intensification of species interactions. The dynamics observed were concordant with the species sorting and mass-effects perspectives of metacommunity theory. Floods cause episodic dispersal in floodplain fish metacommunities, and so, flood frequency determines the relative importance of regional and local processes. Local processes may be particularly important to certain species, but these species may need sufficient time between floods for population increase, before the next flood-induced dispersal episode brings competitors and predators that might cause population decline. Accordingly, species coexistence in these metacommunities may be facilitated by spatiotemporal storage effects, which may in

  4. Energy metabolism affects susceptibility of A. gambiae mosquitoes to Plasmodium infection

    PubMed Central

    Oliveira, Jose Henrique M.; Gonçalves, Renata L.S.; Oliveira, Giselle A.; Oliveira, Pedro L.; Oliveira, Marcus F.; Barillas-Mury, Carolina

    2011-01-01

    Previous studies showed that A. gambiae L35 females, which are refractory (R) to Plasmodium infection, express higher levels of genes involved in redox-metabolism and mitochondrial respiration than susceptible (S) G3 females. Our studies revealed that R females have reduced longevity, faster utilization of lipid reserves, impaired mitochondrial State-3 respiration, increased rate of mitochondrial electron leak and higher expression levels of several glycolytic enzyme genes. Furthermore, when State-3 respiration was reduced in S females by silencing expression of the adenine nucleotide translocator (ANT), hydrogen peroxide generation was higher and the mRNA levels of lactate dehydrogenase increased in the midgut, while the prevalence and intensity of P. berghei infection were significantly reduced. We conclude that there are broad metabolic differences between R and S An. gambiae mosquitoes that influence their susceptibility to Plasmodium infection. PMID:21320598

  5. Defoliation by pastoralists affects savanna tree seedling dynamics by limiting the facilitative role of canopy cover.

    PubMed

    Bufford, Jennifer L; Gaoue, Orou G

    2015-07-01

    Recurrent tree defoliation by pastoralists, akin to herbivory, can negatively affect plant reproduction and population dynamics. However, our understanding of the indirect role of defoliation in seedling recruitment and tree-grass dynamics in tropical savanna is limited. In West African savanna, Fulani pastoralists frequently defoliate several fodder tree species to feed livestock in the dry season. We investigated the direct and indirect effects of recurrent defoliation of African mahogany (Khaya senegalensis) by Fulani people on seedling (< 2 cm basal diameter) and sapling dynamics in West Africa using four years of demographic data on seedling and sapling density, growth, and survival, coupled with fruit production and microhabitat data over the same time period. Tree canopy cover facilitated seedlings but had negative effects on sapling growth possibly via intraspecific competition with adult plants. Interspecific competition with grasses strongly reduced seedling survival but had a weak effect on sapling growth. Fire reduced seedling survival and weakly reduced growth of seedlings and saplings, but did not affect sapling survival. These results indicate that the effect of fire on seedlings and saplings is distinct, a mechanism suitable for an episodic recruitment of seedlings into the sapling stage and consistent with predictions from the demographic bottleneck model. Defoliation affected seedling density and sapling growth through changes in canopy cover, but had no effect on seedling growth and sapling survival. In the moist region, sapling density was higher in sites with low-intensity defoliation, indicating that defoliation may strengthen the tree recruitment bottleneck. Our study suggests that large-scale defoliation can alter the facilitative role of nurse trees on seedling dynamics and tree-sapling competition. Given that tree defoliation by local people is a widespread activity throughout savanna-forest systems in West Africa, it has the potential to

  6. Inhomogeneous Point-Processes to Instantaneously Assess Affective Haptic Perception through Heartbeat Dynamics Information

    NASA Astrophysics Data System (ADS)

    Valenza, G.; Greco, A.; Citi, L.; Bianchi, M.; Barbieri, R.; Scilingo, E. P.

    2016-06-01

    This study proposes the application of a comprehensive signal processing framework, based on inhomogeneous point-process models of heartbeat dynamics, to instantaneously assess affective haptic perception using electrocardiogram-derived information exclusively. The framework relies on inverse-Gaussian point-processes with Laguerre expansion of the nonlinear Wiener-Volterra kernels, accounting for the long-term information given by the past heartbeat events. Up to cubic-order nonlinearities allow for an instantaneous estimation of the dynamic spectrum and bispectrum of the considered cardiovascular dynamics, as well as for instantaneous measures of complexity, through Lyapunov exponents and entropy. Short-term caress-like stimuli were administered for 4.3–25 seconds on the forearms of 32 healthy volunteers (16 females) through a wearable haptic device, by selectively superimposing two levels of force, 2 N and 6 N, and two levels of velocity, 9.4 mm/s and 65 mm/s. Results demonstrated that our instantaneous linear and nonlinear features were able to finely characterize the affective haptic perception, with a recognition accuracy of 69.79% along the force dimension, and 81.25% along the velocity dimension.

  7. Spatial and spatiotemporal variation in metapopulation structure affects population dynamics in a passively dispersing arthropod.

    PubMed

    De Roissart, Annelies; Wang, Shaopeng; Bonte, Dries

    2015-11-01

    The spatial and temporal variation in the availability of suitable habitat within metapopulations determines colonization-extinction events, regulates local population sizes and eventually affects local population and metapopulation stability. Insights into the impact of such a spatiotemporal variation on the local population and metapopulation dynamics are principally derived from classical metapopulation theory and have not been experimentally validated. By manipulating spatial structure in artificial metapopulations of the spider mite Tetranychus urticae, we test to which degree spatial (mainland-island metapopulations) and spatiotemporal variation (classical metapopulations) in habitat availability affects the dynamics of the metapopulations relative to systems where habitat is constantly available in time and space (patchy metapopulations). Our experiment demonstrates that (i) spatial variation in habitat availability decreases variance in metapopulation size and decreases density-dependent dispersal at the metapopulation level, while (ii) spatiotemporal variation in habitat availability increases patch extinction rates, decreases local population and metapopulation sizes and decreases density dependence in population growth rates. We found dispersal to be negatively density dependent and overall low in the spatial variable mainland-island metapopulation. This demographic variation subsequently impacts local and regional population dynamics and determines patterns of metapopulation stability. Both local and metapopulation-level variabilities are minimized in mainland-island metapopulations relative to classical and patchy ones.

  8. How Volatilities Nonlocal in Time Affect the Price Dynamics in Complex Financial Systems

    PubMed Central

    Tan, Lei; Zheng, Bo; Chen, Jun-Jie; Jiang, Xiong-Fei

    2015-01-01

    What is the dominating mechanism of the price dynamics in financial systems is of great interest to scientists. The problem whether and how volatilities affect the price movement draws much attention. Although many efforts have been made, it remains challenging. Physicists usually apply the concepts and methods in statistical physics, such as temporal correlation functions, to study financial dynamics. However, the usual volatility-return correlation function, which is local in time, typically fluctuates around zero. Here we construct dynamic observables nonlocal in time to explore the volatility-return correlation, based on the empirical data of hundreds of individual stocks and 25 stock market indices in different countries. Strikingly, the correlation is discovered to be non-zero, with an amplitude of a few percent and a duration of over two weeks. This result provides compelling evidence that past volatilities nonlocal in time affect future returns. Further, we introduce an agent-based model with a novel mechanism, that is, the asymmetric trading preference in volatile and stable markets, to understand the microscopic origin of the volatility-return correlation nonlocal in time. PMID:25723154

  9. Inhomogeneous Point-Processes to Instantaneously Assess Affective Haptic Perception through Heartbeat Dynamics Information

    NASA Astrophysics Data System (ADS)

    Valenza, G.; Greco, A.; Citi, L.; Bianchi, M.; Barbieri, R.; Scilingo, E. P.

    2016-06-01

    This study proposes the application of a comprehensive signal processing framework, based on inhomogeneous point-process models of heartbeat dynamics, to instantaneously assess affective haptic perception using electrocardiogram-derived information exclusively. The framework relies on inverse-Gaussian point-processes with Laguerre expansion of the nonlinear Wiener-Volterra kernels, accounting for the long-term information given by the past heartbeat events. Up to cubic-order nonlinearities allow for an instantaneous estimation of the dynamic spectrum and bispectrum of the considered cardiovascular dynamics, as well as for instantaneous measures of complexity, through Lyapunov exponents and entropy. Short-term caress-like stimuli were administered for 4.3-25 seconds on the forearms of 32 healthy volunteers (16 females) through a wearable haptic device, by selectively superimposing two levels of force, 2 N and 6 N, and two levels of velocity, 9.4 mm/s and 65 mm/s. Results demonstrated that our instantaneous linear and nonlinear features were able to finely characterize the affective haptic perception, with a recognition accuracy of 69.79% along the force dimension, and 81.25% along the velocity dimension.

  10. Spatial and spatiotemporal variation in metapopulation structure affects population dynamics in a passively dispersing arthropod.

    PubMed

    De Roissart, Annelies; Wang, Shaopeng; Bonte, Dries

    2015-11-01

    The spatial and temporal variation in the availability of suitable habitat within metapopulations determines colonization-extinction events, regulates local population sizes and eventually affects local population and metapopulation stability. Insights into the impact of such a spatiotemporal variation on the local population and metapopulation dynamics are principally derived from classical metapopulation theory and have not been experimentally validated. By manipulating spatial structure in artificial metapopulations of the spider mite Tetranychus urticae, we test to which degree spatial (mainland-island metapopulations) and spatiotemporal variation (classical metapopulations) in habitat availability affects the dynamics of the metapopulations relative to systems where habitat is constantly available in time and space (patchy metapopulations). Our experiment demonstrates that (i) spatial variation in habitat availability decreases variance in metapopulation size and decreases density-dependent dispersal at the metapopulation level, while (ii) spatiotemporal variation in habitat availability increases patch extinction rates, decreases local population and metapopulation sizes and decreases density dependence in population growth rates. We found dispersal to be negatively density dependent and overall low in the spatial variable mainland-island metapopulation. This demographic variation subsequently impacts local and regional population dynamics and determines patterns of metapopulation stability. Both local and metapopulation-level variabilities are minimized in mainland-island metapopulations relative to classical and patchy ones. PMID:25988264

  11. Inhomogeneous Point-Processes to Instantaneously Assess Affective Haptic Perception through Heartbeat Dynamics Information.

    PubMed

    Valenza, G; Greco, A; Citi, L; Bianchi, M; Barbieri, R; Scilingo, E P

    2016-01-01

    This study proposes the application of a comprehensive signal processing framework, based on inhomogeneous point-process models of heartbeat dynamics, to instantaneously assess affective haptic perception using electrocardiogram-derived information exclusively. The framework relies on inverse-Gaussian point-processes with Laguerre expansion of the nonlinear Wiener-Volterra kernels, accounting for the long-term information given by the past heartbeat events. Up to cubic-order nonlinearities allow for an instantaneous estimation of the dynamic spectrum and bispectrum of the considered cardiovascular dynamics, as well as for instantaneous measures of complexity, through Lyapunov exponents and entropy. Short-term caress-like stimuli were administered for 4.3-25 seconds on the forearms of 32 healthy volunteers (16 females) through a wearable haptic device, by selectively superimposing two levels of force, 2 N and 6 N, and two levels of velocity, 9.4 mm/s and 65 mm/s. Results demonstrated that our instantaneous linear and nonlinear features were able to finely characterize the affective haptic perception, with a recognition accuracy of 69.79% along the force dimension, and 81.25% along the velocity dimension. PMID:27357966

  12. Inhomogeneous Point-Processes to Instantaneously Assess Affective Haptic Perception through Heartbeat Dynamics Information

    PubMed Central

    Valenza, G.; Greco, A.; Citi, L.; Bianchi, M.; Barbieri, R.; Scilingo, E. P.

    2016-01-01

    This study proposes the application of a comprehensive signal processing framework, based on inhomogeneous point-process models of heartbeat dynamics, to instantaneously assess affective haptic perception using electrocardiogram-derived information exclusively. The framework relies on inverse-Gaussian point-processes with Laguerre expansion of the nonlinear Wiener-Volterra kernels, accounting for the long-term information given by the past heartbeat events. Up to cubic-order nonlinearities allow for an instantaneous estimation of the dynamic spectrum and bispectrum of the considered cardiovascular dynamics, as well as for instantaneous measures of complexity, through Lyapunov exponents and entropy. Short-term caress-like stimuli were administered for 4.3–25 seconds on the forearms of 32 healthy volunteers (16 females) through a wearable haptic device, by selectively superimposing two levels of force, 2 N and 6 N, and two levels of velocity, 9.4 mm/s and 65 mm/s. Results demonstrated that our instantaneous linear and nonlinear features were able to finely characterize the affective haptic perception, with a recognition accuracy of 69.79% along the force dimension, and 81.25% along the velocity dimension. PMID:27357966

  13. Sexual Behavior and Perceived Peer Norms: Comparing Perinatally HIV-Infected and HIV-Affected Youth

    ERIC Educational Resources Information Center

    Bauermeister, Jose A.; Elkington, Katherine; Brackis-Cott, Elizabeth; Dolezal, Curtis; Mellins, Claude Ann

    2009-01-01

    A large proportion of perinatally HIV-infected (PHIV) children are becoming adolescents and exploring their sexuality. This study explored the prevalence of sexual behaviors (kissing, touching, engaging in oral sex, or having vaginal/anal intercourse) in a sample of predominantly ethnic minority youths (N = 339; 54.1% Black and 30.4% Latino; 51%…

  14. Influenza Virus Affects Intestinal Microbiota and Secondary Salmonella Infection in the Gut through Type I Interferons.

    PubMed

    Deriu, Elisa; Boxx, Gayle M; He, Xuesong; Pan, Calvin; Benavidez, Sammy David; Cen, Lujia; Rozengurt, Nora; Shi, Wenyuan; Cheng, Genhong

    2016-05-01

    Human influenza viruses replicate almost exclusively in the respiratory tract, yet infected individuals may also develop gastrointestinal symptoms, such as vomiting and diarrhea. However, the molecular mechanisms remain incompletely defined. Using an influenza mouse model, we found that influenza pulmonary infection can significantly alter the intestinal microbiota profile through a mechanism dependent on type I interferons (IFN-Is). Notably, influenza-induced IFN-Is produced in the lungs promote the depletion of obligate anaerobic bacteria and the enrichment of Proteobacteria in the gut, leading to a "dysbiotic" microenvironment. Additionally, we provide evidence that IFN-Is induced in the lungs during influenza pulmonary infection inhibit the antimicrobial and inflammatory responses in the gut during Salmonella-induced colitis, further enhancing Salmonella intestinal colonization and systemic dissemination. Thus, our studies demonstrate a systemic role for IFN-Is in regulating the host immune response in the gut during Salmonella-induced colitis and in altering the intestinal microbial balance after influenza infection. PMID:27149619

  15. How do Clostridium difficile infections affect nurses' everyday hospital work: A qualitative study.

    PubMed

    Guillemin, Isabelle; Marrel, Alexia; Beriot-Mathiot, Axelle; Doucet, Carole; Kazoglou, Odysseas; Luxemburger, Christine; Reygrobellet, Camille; Arnould, Benoit

    2015-05-01

    This qualitative study explored the impact of Clostridium difficile infections on nurses' everyday work in the hospital. Twelve nurses (six in France and six in the United States) were interviewed in depth using a semi-structured interview guide. Thematic analysis of the interviews was performed. Managing diarrhoea and taking precautionary measures for infection control were the two most inconvenient aspects nurses reported with C. difficile patient management. Precautions included contact isolation, hand hygiene and reorganization/coordination of nursing care and ward. Precautions were time consuming and significantly increased nurses' workload when combined with caring for patients with uncontrollable, frequent bouts of diarrhoea. Management of C. difficile infection is extremely burdensome for nurses in their everyday work and disruptive to hospital organizations as a whole. Prevention of C. difficile infections, together with coordinated team work and communication, would therefore contribute to decreasing nurses' workload and the burden to health-care facilities associated with caring for these patients.

  16. Influenza Virus Affects Intestinal Microbiota and Secondary Salmonella Infection in the Gut through Type I Interferons

    PubMed Central

    Deriu, Elisa; Boxx, Gayle M.; He, Xuesong; Pan, Calvin; Benavidez, Sammy David; Cen, Lujia; Rozengurt, Nora; Shi, Wenyuan; Cheng, Genhong

    2016-01-01

    Human influenza viruses replicate almost exclusively in the respiratory tract, yet infected individuals may also develop gastrointestinal symptoms, such as vomiting and diarrhea. However, the molecular mechanisms remain incompletely defined. Using an influenza mouse model, we found that influenza pulmonary infection can significantly alter the intestinal microbiota profile through a mechanism dependent on type I interferons (IFN-Is). Notably, influenza-induced IFN-Is produced in the lungs promote the depletion of obligate anaerobic bacteria and the enrichment of Proteobacteria in the gut, leading to a “dysbiotic” microenvironment. Additionally, we provide evidence that IFN-Is induced in the lungs during influenza pulmonary infection inhibit the antimicrobial and inflammatory responses in the gut during Salmonella-induced colitis, further enhancing Salmonella intestinal colonization and systemic dissemination. Thus, our studies demonstrate a systemic role for IFN-Is in regulating the host immune response in the gut during Salmonella-induced colitis and in altering the intestinal microbial balance after influenza infection. PMID:27149619

  17. A modified dynamic evolving neural-fuzzy approach to modeling customer satisfaction for affective design.

    PubMed

    Kwong, C K; Fung, K Y; Jiang, Huimin; Chan, K Y; Siu, Kin Wai Michael

    2013-01-01

    Affective design is an important aspect of product development to achieve a competitive edge in the marketplace. A neural-fuzzy network approach has been attempted recently to model customer satisfaction for affective design and it has been proved to be an effective one to deal with the fuzziness and non-linearity of the modeling as well as generate explicit customer satisfaction models. However, such an approach to modeling customer satisfaction has two limitations. First, it is not suitable for the modeling problems which involve a large number of inputs. Second, it cannot adapt to new data sets, given that its structure is fixed once it has been developed. In this paper, a modified dynamic evolving neural-fuzzy approach is proposed to address the above mentioned limitations. A case study on the affective design of mobile phones was conducted to illustrate the effectiveness of the proposed methodology. Validation tests were conducted and the test results indicated that: (1) the conventional Adaptive Neuro-Fuzzy Inference System (ANFIS) failed to run due to a large number of inputs; (2) the proposed dynamic neural-fuzzy model outperforms the subtractive clustering-based ANFIS model and fuzzy c-means clustering-based ANFIS model in terms of their modeling accuracy and computational effort. PMID:24385884

  18. A shift from exploitation to interference competition with increasing density affects population and community dynamics.

    PubMed

    Holdridge, Erica M; Cuellar-Gempeler, Catalina; terHorst, Casey P

    2016-08-01

    Intraspecific competition influences population and community dynamics and occurs via two mechanisms. Exploitative competition is an indirect effect that occurs through use of a shared resource and depends on resource availability. Interference competition occurs by obstructing access to a resource and may not depend on resource availability. Our study tested whether the strength of interference competition changes with protozoa population density. We grew experimental microcosms of protozoa and bacteria under different combinations of protozoan density and basal resource availability. We then solved a dynamic predator-prey model for parameters of the functional response using population growth rates measured in our experiment. As population density increased, competition shifted from exploitation to interference, and competition was less dependent on resource levels. Surprisingly, the effect of resources was weakest when competition was the most intense. We found that at low population densities, competition was largely exploitative and resource availability had a large effect on population growth rates, but the effect of resources was much weaker at high densities. This shift in competitive mechanism could have implications for interspecific competition, trophic interactions, community diversity, and natural selection. We also tested whether this shift in the mechanism of competition with protozoa density affected the structure of the bacterial prey community. We found that both resources and protozoa density affected the structure of the bacterial prey community, suggesting that competitive mechanism may also affect trophic interactions.

  19. A shift from exploitation to interference competition with increasing density affects population and community dynamics.

    PubMed

    Holdridge, Erica M; Cuellar-Gempeler, Catalina; terHorst, Casey P

    2016-08-01

    Intraspecific competition influences population and community dynamics and occurs via two mechanisms. Exploitative competition is an indirect effect that occurs through use of a shared resource and depends on resource availability. Interference competition occurs by obstructing access to a resource and may not depend on resource availability. Our study tested whether the strength of interference competition changes with protozoa population density. We grew experimental microcosms of protozoa and bacteria under different combinations of protozoan density and basal resource availability. We then solved a dynamic predator-prey model for parameters of the functional response using population growth rates measured in our experiment. As population density increased, competition shifted from exploitation to interference, and competition was less dependent on resource levels. Surprisingly, the effect of resources was weakest when competition was the most intense. We found that at low population densities, competition was largely exploitative and resource availability had a large effect on population growth rates, but the effect of resources was much weaker at high densities. This shift in competitive mechanism could have implications for interspecific competition, trophic interactions, community diversity, and natural selection. We also tested whether this shift in the mechanism of competition with protozoa density affected the structure of the bacterial prey community. We found that both resources and protozoa density affected the structure of the bacterial prey community, suggesting that competitive mechanism may also affect trophic interactions. PMID:27551386

  20. A Modified Dynamic Evolving Neural-Fuzzy Approach to Modeling Customer Satisfaction for Affective Design

    PubMed Central

    Kwong, C. K.; Fung, K. Y.; Jiang, Huimin; Chan, K. Y.

    2013-01-01

    Affective design is an important aspect of product development to achieve a competitive edge in the marketplace. A neural-fuzzy network approach has been attempted recently to model customer satisfaction for affective design and it has been proved to be an effective one to deal with the fuzziness and non-linearity of the modeling as well as generate explicit customer satisfaction models. However, such an approach to modeling customer satisfaction has two limitations. First, it is not suitable for the modeling problems which involve a large number of inputs. Second, it cannot adapt to new data sets, given that its structure is fixed once it has been developed. In this paper, a modified dynamic evolving neural-fuzzy approach is proposed to address the above mentioned limitations. A case study on the affective design of mobile phones was conducted to illustrate the effectiveness of the proposed methodology. Validation tests were conducted and the test results indicated that: (1) the conventional Adaptive Neuro-Fuzzy Inference System (ANFIS) failed to run due to a large number of inputs; (2) the proposed dynamic neural-fuzzy model outperforms the subtractive clustering-based ANFIS model and fuzzy c-means clustering-based ANFIS model in terms of their modeling accuracy and computational effort. PMID:24385884

  1. Ciprofloxacin Derivatives Affect Parasite Cell Division and Increase the Survival of Mice Infected with Toxoplasma gondii

    PubMed Central

    Martins-Duarte, Erica S.; Dubar, Faustine; Lawton, Philippe; França da Silva, Cristiane; C. Soeiro, Maria de Nazaré; de Souza, Wanderley; Biot, Christophe; Vommaro, Rossiane C.

    2015-01-01

    Toxoplasmosis, caused by the protozoan Toxoplasma gondii, is a worldwide disease whose clinical manifestations include encephalitis and congenital malformations in newborns. Previously, we described the synthesis of new ethyl-ester derivatives of the antibiotic ciprofloxacin with ~40-fold increased activity against T. gondii in vitro, compared with the original compound. Cipro derivatives are expected to target the parasite’s DNA gyrase complex in the apicoplast. The activity of these compounds in vivo, as well as their mode of action, remained thus far uncharacterized. Here, we examined the activity of the Cipro derivatives in vivo, in a model of acute murine toxoplasmosis. In addition, we investigated the cellular effects T. gondii tachyzoites in vitro, by immunofluorescence and transmission electron microscopy (TEM). When compared with Cipro treatment, 7-day treatments with Cipro derivatives increased mouse survival significantly, with 13–25% of mice surviving for up to 60 days post-infection (vs. complete lethality 10 days post-infection, with Cipro treatment). Light microscopy examination early (6 and 24h) post-infection revealed that 6-h treatments with Cipro derivatives inhibited the initial event of parasite cell division inside host cells, in an irreversible manner. By TEM and immunofluorescence, the main cellular effects observed after treatment with Cipro derivatives and Cipro were cell scission inhibition - with the appearance of ‘tethered’ parasites – malformation of the inner membrane complex, and apicoplast enlargement and missegregation. Interestingly, tethered daughter cells resulting from Cipro derivatives, and also Cipro, treatment did not show MORN1 cap or centrocone localization. The biological activity of Cipro derivatives against C. parvum, an apicomplexan species that lacks the apicoplast, is, approximately, 50 fold lower than that in T. gondii tachyzoites, supporting that these compounds targets the apicoplast. Our results show

  2. Ciprofloxacin Derivatives Affect Parasite Cell Division and Increase the Survival of Mice Infected with Toxoplasma gondii.

    PubMed

    Martins-Duarte, Erica S; Dubar, Faustine; Lawton, Philippe; da Silva, Cristiane França; Soeiro, Maria de Nazaré C; de Souza, Wanderley; Biot, Christophe; Vommaro, Rossiane C

    2015-01-01

    Toxoplasmosis, caused by the protozoan Toxoplasma gondii, is a worldwide disease whose clinical manifestations include encephalitis and congenital malformations in newborns. Previously, we described the synthesis of new ethyl-ester derivatives of the antibiotic ciprofloxacin with ~40-fold increased activity against T. gondii in vitro, compared with the original compound. Cipro derivatives are expected to target the parasite's DNA gyrase complex in the apicoplast. The activity of these compounds in vivo, as well as their mode of action, remained thus far uncharacterized. Here, we examined the activity of the Cipro derivatives in vivo, in a model of acute murine toxoplasmosis. In addition, we investigated the cellular effects T. gondii tachyzoites in vitro, by immunofluorescence and transmission electron microscopy (TEM). When compared with Cipro treatment, 7-day treatments with Cipro derivatives increased mouse survival significantly, with 13-25% of mice surviving for up to 60 days post-infection (vs. complete lethality 10 days post-infection, with Cipro treatment). Light microscopy examination early (6 and 24h) post-infection revealed that 6-h treatments with Cipro derivatives inhibited the initial event of parasite cell division inside host cells, in an irreversible manner. By TEM and immunofluorescence, the main cellular effects observed after treatment with Cipro derivatives and Cipro were cell scission inhibition--with the appearance of 'tethered' parasites--malformation of the inner membrane complex, and apicoplast enlargement and missegregation. Interestingly, tethered daughter cells resulting from Cipro derivatives, and also Cipro, treatment did not show MORN1 cap or centrocone localization. The biological activity of Cipro derivatives against C. parvum, an apicomplexan species that lacks the apicoplast, is, approximately, 50 fold lower than that in T. gondii tachyzoites, supporting that these compounds targets the apicoplast. Our results show that Cipro

  3. The effects of distributed life cycles on the dynamics of viral infections.

    PubMed

    Campos, Daniel; Méndez, Vicenç; Fedotov, Sergei

    2008-09-21

    We explore the role of cellular life cycles for viruses and host cells in an infection process. For this purpose, we derive a generalized version of the basic model of virus dynamics (Nowak, M.A., Bangham, C.R.M., 1996. Population dynamics of immune responses to persistent viruses. Science 272, 74-79) from a mesoscopic description. In its final form the model can be written as a set of Volterra integrodifferential equations. We consider the role of distributed lifespans and a intracellular (eclipse) phase. These processes are implemented by means of probability distribution functions. The basic reproductive ratio R(0) of the infection is properly defined in terms of such distributions by using an analysis of the equilibrium states and their stability. It is concluded that the introduction of distributed delays can strongly modify both the value of R(0) and the predictions for the virus loads, so the effects on the infection dynamics are of major importance. We also show how the model presented here can be applied to some simple situations where direct comparison with experiments is possible. Specifically, phage-bacteria interactions are analyzed. The dynamics of the eclipse phase for phages is characterized analytically, which allows us to compare the performance of three different fittings proposed before for the one-step growth curve. PMID:18573261

  4. Ranking landscape development scenarios affecting natterjack toad (Bufo calamita) population dynamics in Central Poland.

    PubMed

    Franz, Kamila W; Romanowski, Jerzy; Johst, Karin; Grimm, Volker

    2013-01-01

    When data are limited it is difficult for conservation managers to assess alternative management scenarios and make decisions. The natterjack toad (Bufo calamita) is declining at the edges of its distribution range in Europe and little is known about its current distribution and abundance in Poland. Although different landscape management plans for central Poland exist, it is unclear to what extent they impact this species. Based on these plans, we investigated how four alternative landscape development scenarios would affect the total carrying capacity and population dynamics of the natterjack toad. To facilitate decision-making, we first ranked the scenarios according to their total carrying capacity. We used the software RAMAS GIS to determine the size and location of habitat patches in the landscape. The estimated carrying capacities were very similar for each scenario, and clear ranking was not possible. Only the reforestation scenario showed a marked loss in carrying capacity. We therefore simulated metapopulation dynamics with RAMAS taking into account dynamical processes such as reproduction and dispersal and ranked the scenarios according to the resulting species abundance. In this case, we could clearly rank the development scenarios. We identified road mortality of adults as a key process governing the dynamics and separating the different scenarios. The renaturalisation scenario clearly ranked highest due to its decreased road mortality. Taken together our results suggest that road infrastructure development might be much more important for natterjack toad conservation than changes in the amount of habitat in the semi-natural river valley. We gained these insights by considering both the resulting metapopulation structure and dynamics in the form of a PVA. We conclude that the consideration of dynamic processes in amphibian conservation management may be indispensable for ranking management scenarios.

  5. Ranking Landscape Development Scenarios Affecting Natterjack Toad (Bufo calamita) Population Dynamics in Central Poland

    PubMed Central

    Franz, Kamila W.; Romanowski, Jerzy; Johst, Karin; Grimm, Volker

    2013-01-01

    When data are limited it is difficult for conservation managers to assess alternative management scenarios and make decisions. The natterjack toad (Bufo calamita) is declining at the edges of its distribution range in Europe and little is known about its current distribution and abundance in Poland. Although different landscape management plans for central Poland exist, it is unclear to what extent they impact this species. Based on these plans, we investigated how four alternative landscape development scenarios would affect the total carrying capacity and population dynamics of the natterjack toad. To facilitate decision-making, we first ranked the scenarios according to their total carrying capacity. We used the software RAMAS GIS to determine the size and location of habitat patches in the landscape. The estimated carrying capacities were very similar for each scenario, and clear ranking was not possible. Only the reforestation scenario showed a marked loss in carrying capacity. We therefore simulated metapopulation dynamics with RAMAS taking into account dynamical processes such as reproduction and dispersal and ranked the scenarios according to the resulting species abundance. In this case, we could clearly rank the development scenarios. We identified road mortality of adults as a key process governing the dynamics and separating the different scenarios. The renaturalisation scenario clearly ranked highest due to its decreased road mortality. Taken together our results suggest that road infrastructure development might be much more important for natterjack toad conservation than changes in the amount of habitat in the semi-natural river valley. We gained these insights by considering both the resulting metapopulation structure and dynamics in the form of a PVA. We conclude that the consideration of dynamic processes in amphibian conservation management may be indispensable for ranking management scenarios. PMID:23734223

  6. Arabidopsis FH1 Formin Affects Cotyledon Pavement Cell Shape by Modulating Cytoskeleton Dynamics.

    PubMed

    Rosero, Amparo; Oulehlová, Denisa; Stillerová, Lenka; Schiebertová, Petra; Grunt, Michal; Žárský, Viktor; Cvrčková, Fatima

    2016-03-01

    Plant cell morphogenesis involves concerted rearrangements of microtubules and actin microfilaments. We previously reported that FH1, the main Arabidopsis thaliana housekeeping Class I membrane-anchored formin, contributes to actin dynamics and microtubule stability in rhizodermis cells. Here we examine the effects of mutations affecting FH1 (At3g25500) on cell morphogenesis and above-ground organ development in seedlings, as well as on cytoskeletal organization and dynamics, using a combination of confocal and variable angle epifluorescence microscopy with a pharmacological approach. Homozygous fh1 mutants exhibited cotyledon epinasty and had larger cotyledon pavement cells with more pronounced lobes than the wild type. The pavement cell shape alterations were enhanced by expression of the fluorescent microtubule marker GFP-microtubule-associated protein 4 (MAP4). Mutant cotyledon pavement cells exhibited reduced density and increased stability of microfilament bundles, as well as enhanced dynamics of microtubules. Analogous results were also obtained upon treatments with the formin inhibitor SMIFH2 (small molecule inhibitor of formin homology 2 domains). Pavement cell shape in wild-type (wt) and fh1 plants in some situations exhibited a differential response towards anti-cytoskeletal drugs, especially the microtubule disruptor oryzalin. Our observations indicate that FH1 participates in the control of microtubule dynamics, possibly via its effects on actin, subsequently influencing cell morphogenesis and macroscopic organ development. PMID:26738547

  7. Arabidopsis FH1 Formin Affects Cotyledon Pavement Cell Shape by Modulating Cytoskeleton Dynamics.

    PubMed

    Rosero, Amparo; Oulehlová, Denisa; Stillerová, Lenka; Schiebertová, Petra; Grunt, Michal; Žárský, Viktor; Cvrčková, Fatima

    2016-03-01

    Plant cell morphogenesis involves concerted rearrangements of microtubules and actin microfilaments. We previously reported that FH1, the main Arabidopsis thaliana housekeeping Class I membrane-anchored formin, contributes to actin dynamics and microtubule stability in rhizodermis cells. Here we examine the effects of mutations affecting FH1 (At3g25500) on cell morphogenesis and above-ground organ development in seedlings, as well as on cytoskeletal organization and dynamics, using a combination of confocal and variable angle epifluorescence microscopy with a pharmacological approach. Homozygous fh1 mutants exhibited cotyledon epinasty and had larger cotyledon pavement cells with more pronounced lobes than the wild type. The pavement cell shape alterations were enhanced by expression of the fluorescent microtubule marker GFP-microtubule-associated protein 4 (MAP4). Mutant cotyledon pavement cells exhibited reduced density and increased stability of microfilament bundles, as well as enhanced dynamics of microtubules. Analogous results were also obtained upon treatments with the formin inhibitor SMIFH2 (small molecule inhibitor of formin homology 2 domains). Pavement cell shape in wild-type (wt) and fh1 plants in some situations exhibited a differential response towards anti-cytoskeletal drugs, especially the microtubule disruptor oryzalin. Our observations indicate that FH1 participates in the control of microtubule dynamics, possibly via its effects on actin, subsequently influencing cell morphogenesis and macroscopic organ development.

  8. Impact of asymptomatic infection on coupled disease-behavior dynamics in complex networks

    NASA Astrophysics Data System (ADS)

    Zhang, Hai-Feng; Xie, Jia-Rong; Chen, Han-Shuang; Liu, Can; Small, Michael

    2016-05-01

    Studies on how to model the interplay between diseases and behavioral responses (so-called coupled disease-behavior interaction) have attracted increasing attention. Owing to the lack of obvious clinical evidence of diseases, or the incomplete information related to the disease, the risks of infection cannot be perceived and may lead to inappropriate behavioral responses. Therefore, how to quantitatively analyze the impacts of asymptomatic infection on the interplay between diseases and behavioral responses is of particular importance. In this letter, under the complex network framework, we study the coupled disease-behavior interaction model by dividing infectious individuals into two states: U-state (without evident clinical symptoms, labelled as U) and I-state (with evident clinical symptoms, labelled as I). A susceptible individual can be infected by U- or I-nodes, however, since the U-nodes cannot be easily observed, susceptible individuals take behavioral responses only when they contact I-nodes. The mechanism is considered in the improved Susceptible-Infected-Susceptible (SIS) model and the improved Susceptible-Infected-Recovered (SIR) model, respectively. Then, one of the most concerned problems in spreading dynamics: the epidemic thresholds for the two models are given by two methods. The analytic results quantitatively describe the influence of different factors, such as asymptomatic infection, the awareness rate, the network structure, and so forth, on the epidemic thresholds. Moreover, because of the irreversible process of the SIR model, the suppression effect of the improved SIR model is weaker than the improved SIS model.

  9. Exceptional Heterogeneity in Viral Evolutionary Dynamics Characterises Chronic Hepatitis C Virus Infection

    PubMed Central

    Lemey, Philippe; Farci, Patrizia; Pybus, Oliver G.

    2016-01-01

    The treatment of HCV infection has seen significant progress, particularly since the approval of new direct-acting antiviral drugs. However these clinical achievements have been made despite an incomplete understanding of HCV replication and within-host evolution, especially compared with HIV-1. Here, we undertake a comprehensive analysis of HCV within-host evolution during chronic infection by investigating over 4000 viral sequences sampled longitudinally from 15 HCV-infected patients. We compare our HCV results to those from a well-studied HIV-1 cohort, revealing key differences in the evolutionary behaviour of these two chronic-infecting pathogens. Notably, we find an exceptional level of heterogeneity in the molecular evolution of HCV, both within and among infected individuals. Furthermore, these patterns are associated with the long-term maintenance of viral lineages within patients, which fluctuate in relative frequency in peripheral blood. Together, our findings demonstrate that HCV replication behavior is complex and likely comprises multiple viral subpopulations with distinct evolutionary dynamics. The presence of a structured viral population can explain apparent paradoxes in chronic HCV infection, such as rapid fluctuations in viral diversity and the reappearance of viral strains years after their initial detection. PMID:27631086

  10. Exceptional Heterogeneity in Viral Evolutionary Dynamics Characterises Chronic Hepatitis C Virus Infection.

    PubMed

    Raghwani, Jayna; Rose, Rebecca; Sheridan, Isabelle; Lemey, Philippe; Suchard, Marc A; Santantonio, Teresa; Farci, Patrizia; Klenerman, Paul; Pybus, Oliver G

    2016-09-01

    The treatment of HCV infection has seen significant progress, particularly since the approval of new direct-acting antiviral drugs. However these clinical achievements have been made despite an incomplete understanding of HCV replication and within-host evolution, especially compared with HIV-1. Here, we undertake a comprehensive analysis of HCV within-host evolution during chronic infection by investigating over 4000 viral sequences sampled longitudinally from 15 HCV-infected patients. We compare our HCV results to those from a well-studied HIV-1 cohort, revealing key differences in the evolutionary behaviour of these two chronic-infecting pathogens. Notably, we find an exceptional level of heterogeneity in the molecular evolution of HCV, both within and among infected individuals. Furthermore, these patterns are associated with the long-term maintenance of viral lineages within patients, which fluctuate in relative frequency in peripheral blood. Together, our findings demonstrate that HCV replication behavior is complex and likely comprises multiple viral subpopulations with distinct evolutionary dynamics. The presence of a structured viral population can explain apparent paradoxes in chronic HCV infection, such as rapid fluctuations in viral diversity and the reappearance of viral strains years after their initial detection. PMID:27631086

  11. Survival of Mycobacterium avium subsp. paratuberculosis in bovine monocyte-derived macrophages is not affected by host infection status but depends on the infecting bacterial genotype.

    PubMed

    Gollnick, Nicole S; Mitchell, Rebecca M; Baumgart, Martin; Janagama, Harish K; Sreevatsan, Srinand; Schukken, Ynte H

    2007-12-15

    In this study we investigated the ability of different Mycobacterium avium subsp. paratuberculosis (M. paratuberculosis) strains to survive in bovine monocyte-derived macrophages (MDMs) of cows naturally infected with M. paratuberculosis and control cows. We tested the hypotheses that infection status of cows affects macrophage killing ability and that survival of M. paratuberculosis in macrophages is dependent on the strain. Peripheral blood mononuclear cells (PBMC) were obtained from Johne's disease-positive (n=3) and age and stage of lactation matched Johne's disease-negative (n=3) multiparious cows. Following differentiation, MDMs were challenged in vitro with four M. paratuberculosis strains of different host specificity (cattle and sheep). Two hours and 2, 4, and 7 days after infection, ingestion, and intracellular survival of M. paratuberculosis strains were determined by fluorescence microscopy. There was no effect of the origin of MDMs (Johne's disease-positive or control animals) on phagocytosis, survival of bacteria, or macrophage survival. In contrast, important strain differences were observed. These findings suggest that some M. paratuberculosis strains interfere more successfully than others with the ability of macrophages to kill intracellular pathogens which may make it important to include strain typing when designing control programs.

  12. Diet and feeding pattern affect the diurnal dynamics of the gut microbiome.

    PubMed

    Zarrinpar, Amir; Chaix, Amandine; Yooseph, Shibu; Panda, Satchidananda

    2014-12-01

    The gut microbiome and daily feeding/fasting cycle influence host metabolism and contribute to obesity and metabolic diseases. However, fundamental characteristics of this relationship between the feeding/fasting cycle and the gut microbiome are unknown. Our studies show that the gut microbiome is highly dynamic, exhibiting daily cyclical fluctuations in composition. Diet-induced obesity dampens the daily feeding/fasting rhythm and diminishes many of these cyclical fluctuations. Time-restricted feeding (TRF), in which feeding is consolidated to the nocturnal phase, partially restores these cyclical fluctuations. Furthermore, TRF, which protects against obesity and metabolic diseases, affects bacteria shown to influence host metabolism. Cyclical changes in the gut microbiome from feeding/fasting rhythms contribute to the diversity of gut microflora and likely represent a mechanism by which the gut microbiome affects host metabolism. Thus, feeding pattern and time of harvest, in addition to diet, are important parameters when assessing the microbiome's contribution to host metabolism.

  13. Ionizing air affects influenza virus infectivity and prevents airborne-transmission.

    PubMed

    Hagbom, Marie; Nordgren, Johan; Nybom, Rolf; Hedlund, Kjell-Olof; Wigzell, Hans; Svensson, Lennart

    2015-01-01

    By the use of a modified ionizer device we describe effective prevention of airborne transmitted influenza A (strain Panama 99) virus infection between animals and inactivation of virus (>97%). Active ionizer prevented 100% (4/4) of guinea pigs from infection. Moreover, the device effectively captured airborne transmitted calicivirus, rotavirus and influenza virus, with recovery rates up to 21% after 40 min in a 19 m(3) room. The ionizer generates negative ions, rendering airborne particles/aerosol droplets negatively charged and electrostatically attracts them to a positively charged collector plate. Trapped viruses are then identified by reverse transcription quantitative real-time PCR. The device enables unique possibilities for rapid and simple removal of virus from air and offers possibilities to simultaneously identify and prevent airborne transmission of viruses. PMID:26101102

  14. Ionizing air affects influenza virus infectivity and prevents airborne-transmission

    PubMed Central

    Hagbom, Marie; Nordgren, Johan; Nybom, Rolf; Hedlund, Kjell-Olof; Wigzell, Hans; Svensson, Lennart

    2015-01-01

    By the use of a modified ionizer device we describe effective prevention of airborne transmitted influenza A (strain Panama 99) virus infection between animals and inactivation of virus (>97%). Active ionizer prevented 100% (4/4) of guinea pigs from infection. Moreover, the device effectively captured airborne transmitted calicivirus, rotavirus and influenza virus, with recovery rates up to 21% after 40 min in a 19 m3 room. The ionizer generates negative ions, rendering airborne particles/aerosol droplets negatively charged and electrostatically attracts them to a positively charged collector plate. Trapped viruses are then identified by reverse transcription quantitative real-time PCR. The device enables unique possibilities for rapid and simple removal of virus from air and offers possibilities to simultaneously identify and prevent airborne transmission of viruses. PMID:26101102

  15. Viral affects on metabolism: changes in glucose and glutamine utilization during human cytomegalovirus infection

    PubMed Central

    Yu, Yongjun; Clippinger, Amy J.; Alwine, James C.

    2011-01-01

    Human cytomegalovirus (HCMV) infection causes dramatic alterations of intermediary metabolism, similar to those found in tumor cells. In infected cells, glucose carbon is not completely broken down by the tricarboxylic acid (TCA) cycle for energy; instead it is used biosynthetically. This process requires increased glucose uptake, increased glycolysis and the diversion of glucose carbon, in the form of citrate, from the TCA cycle for use in HCMV-induced fatty acid biosynthesis. The diversion of citrate from the TCA cycle (cataplerosis) requires induction of enzymes to promote glutaminolysis, the conversion of glutamine to -ketoglutarate in order to maintain the TCA cycle (anaplerosis) and ATP production. Such changes could result in heretofore uncharacterized pathogenesis, potentially implicating HCMV as a subtle co-factor in many maladies, including oncogenesis. Recognition of the effects of HCMV, and other viruses, on host cell metabolism will provide new understanding of viral pathogenesis and novel avenues for antiviral therapy. PMID:21570293

  16. Soboliphyme baturini infection does not affect the nutritional condition of American marten (Martes americana) in Alaska.

    PubMed

    Thomas, J G; Pauli, J N; Donadio, E; Buskirk, S W

    2008-12-01

    Soboliphyme baturini, a stomach-dwelling nematode of American martens (Martes Americana), reaches high levels of infection; however, its effects on the nutritional condition of the host are unknown. To understand the effects of this parasite on American martens, we collected S. baturini and measured abdominal fat deposits from 155 marten carcasses on Prince of Wales Island, southeastern Alaska, in the winter 2006-2007. We analyzed how the dried mass of abdominal fat varied as a function of S. baturini intensity. Parasite intensity and nutritional condition were not correlated; these results suggest that American martens were able to withstand even very high levels of S. baturini infection (up to 178 parasites per host). PMID:18576861

  17. Soboliphyme baturini infection does not affect the nutritional condition of American marten (Martes americana) in Alaska.

    PubMed

    Thomas, J G; Pauli, J N; Donadio, E; Buskirk, S W

    2008-12-01

    Soboliphyme baturini, a stomach-dwelling nematode of American martens (Martes Americana), reaches high levels of infection; however, its effects on the nutritional condition of the host are unknown. To understand the effects of this parasite on American martens, we collected S. baturini and measured abdominal fat deposits from 155 marten carcasses on Prince of Wales Island, southeastern Alaska, in the winter 2006-2007. We analyzed how the dried mass of abdominal fat varied as a function of S. baturini intensity. Parasite intensity and nutritional condition were not correlated; these results suggest that American martens were able to withstand even very high levels of S. baturini infection (up to 178 parasites per host).

  18. Plant waxy bloom on peas affects infection of pea aphids by Pandora neoaphidis.

    PubMed

    Duetting, Patrick S; Ding, Hongjian; Neufeld, Jeffrey; Eigenbrode, Sanford D

    2003-11-01

    This study examined the effects of the surface wax bloom of pea plants, Pisum sativum, on infection of pea aphids, Acyrthosiphon pisum, by the fungal pathogen Pandora neoaphidis. In prior field surveys, a higher proportion of P. neoaphidis-killed pea aphids (cadavers) had been observed on a pea line with reduced wax bloom, as compared with a sister line with normal surface wax bloom. Laboratory bioassays were conducted in order to examine the mechanisms. After plants of each line infested with aphids were exposed to similar densities of conidia, the rate of accumulation of cadavers on the reduced wax line was significantly greater than on the normal wax bloom line; at the end of the experiment (13d), the proportion of aphid cadavers on the reduced wax line was approximately four times that on the normal wax bloom line. When plants were exposed to conidia first and then infested with aphids, the rate of accumulation of cadavers was slightly but significantly greater on the reduced wax line, and infection at the end of the experiment (16d) did not differ between the lines. When aphids were exposed first and then released onto the plants, no differences in the proportion of aphid cadavers were observed between the pea lines. Greater infection of pea aphid on reduced wax peas appears to depend upon plants being exposed to inoculum while aphids are settled in typical feeding positions on the plant. Additional experiments demonstrated increased adhesion and germination by P. neoaphidis conidia to leaf surfaces of the reduced wax line as compared with normal wax line, and this could help explain the higher infection rate by P. neoaphidis on the reduced wax line. In bioassays using surface waxes extracted from the two lines, there was no effect of wax source on germination of P. neoaphidis conidia.

  19. ABO desensitization affects cellular immunity and infection control after renal transplantation.

    PubMed

    Schachtner, Thomas; Stein, Maik; Reinke, Petra

    2015-10-01

    The impact of ABO desensitization on overall immunity, infectious control, and alloreactivity remains unknown. We compared 35 ABO-incompatible kidney transplant recipients (KTRs) to a control of 62 ABO compatible KTRs. Samples were collected before, at +1, +2, +3, +6, and +12 months post-transplantation. CMV-, BKV-specific, and alloreactive T cells were measured using an interferon-γ ELISPOT assay. The extent of immunosuppression was quantified by enumeration of lymphocyte subpopulations and cytokines. No differences were observed for 5-year allograft survival and function between both groups (P > 0.05). However, ABO-incompatible KTRs were more likely to develop CMV infection, BKV-associated nephropathy, and severe sepsis (P = 0.001). Interestingly, ABO-incompatible KTRs with poor HLA-match showed the highest rates of infections and inferior allograft function (P < 0.05). CD3+, CD4+ T-cell counts, interferon-γ and IL-10 levels were lower in ABO-incompatible KTRs early post-transplantation (P < 0.05). Likewise, ABO-incompatible KTRs showed impaired BKV- and CMV-specific T-cell immunity (P < 0.05). ABO-incompatible KTRs showed lower frequencies of alloreactive T cells (P < 0.05). Our data suggest T-cell depletion due to ABO desensitization, which may contribute to the increased risk of T-cell-dependent infections. Elimination of B cells serving as antigen-presenting cells, thereby causing impaired T-cell activation, plays a significant role in both impaired infection control and reduced alloreactive T-cell activation.

  20. Comparison of Soybean Transformation Efficiency and Plant Factors Affecting Transformation during the Agrobacterium Infection Process

    PubMed Central

    Jia, Yuying; Yao, Xingdong; Zhao, Mingzhe; Zhao, Qiang; Du, Yanli; Yu, Cuimei; Xie, Futi

    2015-01-01

    The susceptibility of soybean genotype to Agrobacterium infection is a key factor for the high level of genetic transformation efficiency. The objective of this study is to evaluate the plant factors related to transformation in cotyledonary nodes during the Agrobacterium infection process. This study selected three genotypes (Williams 82, Shennong 9 and Bert) with high transformation efficiency, which presented better susceptibility to Agrobacterium infection, and three low transformation efficiency genotypes (General, Liaodou 16 and Kottman), which showed a relatively weak susceptibility. Gibberellin (GA) levels and soybean GA20ox2 and CYP707A2 transcripts of high-efficiency genotypes increased and were higher than those of low-efficiency genotypes; however, the opposite performance was shown in abscisic acid (ABA). Higher zeatin riboside (ZR) content and DNA quantity, and relatively higher expression of soybean IPT5, CYCD3 and CYCA3 were obtained in high-efficiency genotypes. High-efficiency genotypes had low methyl jasmonate (MeJA) content, polyphenol oxidase (PPO) and peroxidase (POD) activity, and relatively lower expression of soybean OPR3, PPO1 and PRX71. GA and ZR were positive plant factors for Agrobacterium-mediated soybean transformation by facilitating germination and growth, and increasing the number of cells in DNA synthesis cycle, respectively; MeJA, PPO, POD and ABA were negative plant factors by inducing defence reactions and repressing germination and growth, respectively. PMID:26262617

  1. Social group size affects Mycobacterium bovis infection in European badgers (Meles meles).

    PubMed

    Woodroffe, Rosie; Donnelly, Christl A; Wei, Gao; Cox, D R; Bourne, F John; Burke, Terry; Butlin, Roger K; Cheeseman, C L; Gettinby, George; Gilks, Peter; Hedges, Simon; Jenkins, Helen E; Johnston, W Thomas; McInerney, John P; Morrison, W Ivan; Pope, Lisa C

    2009-07-01

    1. In most social animals, the prevalence of directly transmitted pathogens increases in larger groups and at higher population densities. Such patterns are predicted by models of Mycobacterium bovis infection in European badgers (Meles meles). 2. We investigated the relationship between badger abundance and M. bovis prevalence, using data on 2696 adult badgers in 10 populations sampled at the start of the Randomized Badger Culling Trial. 3. M. bovis prevalence was consistently higher at low badger densities and in small social groups. M. bovis prevalence was also higher among badgers whose genetic profiles suggested that they had immigrated into their assigned social groups. 4. The association between high M. bovis prevalence and small badger group size appeared not to have been caused by previous small-scale culling in study areas, which had been suspended, on average, 5 years before the start of the current study. 5. The observed pattern of prevalence might occur through badgers in smaller groups interacting more frequently with members of neighbouring groups; detailed behavioural data are needed to test this hypothesis. Likewise, longitudinal data are needed to determine whether the size of infected groups might be suppressed by disease-related mortality. 6. Although M. bovis prevalence was lower at high population densities, the absolute number of infected badgers was higher. However, this does not necessarily mean that the risk of M. bovis transmission to cattle is highest at high badger densities, since transmission risk depends on badger behaviour as well as on badger density. PMID:19486382

  2. Comparison of Soybean Transformation Efficiency and Plant Factors Affecting Transformation during the Agrobacterium Infection Process.

    PubMed

    Jia, Yuying; Yao, Xingdong; Zhao, Mingzhe; Zhao, Qiang; Du, Yanli; Yu, Cuimei; Xie, Futi

    2015-08-07

    The susceptibility of soybean genotype to Agrobacterium infection is a key factor for the high level of genetic transformation efficiency. The objective of this study is to evaluate the plant factors related to transformation in cotyledonary nodes during the Agrobacterium infection process. This study selected three genotypes (Williams 82, Shennong 9 and Bert) with high transformation efficiency, which presented better susceptibility to Agrobacterium infection, and three low transformation efficiency genotypes (General, Liaodou 16 and Kottman), which showed a relatively weak susceptibility. Gibberellin (GA) levels and soybean GA20ox2 and CYP707A2 transcripts of high-efficiency genotypes increased and were higher than those of low-efficiency genotypes; however, the opposite performance was shown in abscisic acid (ABA). Higher zeatin riboside (ZR) content and DNA quantity, and relatively higher expression of soybean IPT5, CYCD3 and CYCA3 were obtained in high-efficiency genotypes. High-efficiency genotypes had low methyl jasmonate (MeJA) content, polyphenol oxidase (PPO) and peroxidase (POD) activity, and relatively lower expression of soybean OPR3, PPO1 and PRX71. GA and ZR were positive plant factors for Agrobacterium-mediated soybean transformation by facilitating germination and growth, and increasing the number of cells in DNA synthesis cycle, respectively; MeJA, PPO, POD and ABA were negative plant factors by inducing defence reactions and repressing germination and growth, respectively.

  3. Root Respiration and Growth in Plantago major as Affected by Vesicular-Arbuscular Mycorrhizal Infection.

    PubMed

    Baas, R; van der Werf, A; Lambers, H

    1989-09-01

    Effects of vesicular-arbuscular mycorrhizal (VAM) infection and P on root respiration and dry matter allocation were studied in Plantago major L. ssp. pleiosperma (Pilger). By applying P, the relative growth rate of non-VAM controls and plants colonized by Glomus fasciculatum (Thaxt. sensu Gerdemann) Gerdemann and Trappe was increased to a similar extent (55-67%). However, leaf area ratio was increased more and net assimilation rate per unit leaf area was increased less by VAM infection than by P addition. The lower net assimilation rate could be related to a 20 to 30% higher root respiration rate per unit leaf area of VAM plants. Root respiration per unit dry matter and specific net uptake rates of N and P were increased more by VAM infection than by P addition. Neither the contribution of the alternative respiratory path nor the relative growth rate could account for the differences in root respiration rate between VAM and non-VAM plants. It was estimated that increased fungal respiration (87%) and ion uptake rate (13%) contributed to the higher respiratory activity of VAM roots of P. major. PMID:16667001

  4. Root Respiration and Growth in Plantago major as Affected by Vesicular-Arbuscular Mycorrhizal Infection 1

    PubMed Central

    Baas, Rob; van der Werf, Adrie; Lambers, Hans

    1989-01-01

    Effects of vesicular-arbuscular mycorrhizal (VAM) infection and P on root respiration and dry matter allocation were studied in Plantago major L. ssp. pleiosperma (Pilger). By applying P, the relative growth rate of non-VAM controls and plants colonized by Glomus fasciculatum (Thaxt. sensu Gerdemann) Gerdemann and Trappe was increased to a similar extent (55-67%). However, leaf area ratio was increased more and net assimilation rate per unit leaf area was increased less by VAM infection than by P addition. The lower net assimilation rate could be related to a 20 to 30% higher root respiration rate per unit leaf area of VAM plants. Root respiration per unit dry matter and specific net uptake rates of N and P were increased more by VAM infection than by P addition. Neither the contribution of the alternative respiratory path nor the relative growth rate could account for the differences in root respiration rate between VAM and non-VAM plants. It was estimated that increased fungal respiration (87%) and ion uptake rate (13%) contributed to the higher respiratory activity of VAM roots of P. major. PMID:16667001

  5. Social group size affects Mycobacterium bovis infection in European badgers (Meles meles).

    PubMed

    Woodroffe, Rosie; Donnelly, Christl A; Wei, Gao; Cox, D R; Bourne, F John; Burke, Terry; Butlin, Roger K; Cheeseman, C L; Gettinby, George; Gilks, Peter; Hedges, Simon; Jenkins, Helen E; Johnston, W Thomas; McInerney, John P; Morrison, W Ivan; Pope, Lisa C

    2009-07-01

    1. In most social animals, the prevalence of directly transmitted pathogens increases in larger groups and at higher population densities. Such patterns are predicted by models of Mycobacterium bovis infection in European badgers (Meles meles). 2. We investigated the relationship between badger abundance and M. bovis prevalence, using data on 2696 adult badgers in 10 populations sampled at the start of the Randomized Badger Culling Trial. 3. M. bovis prevalence was consistently higher at low badger densities and in small social groups. M. bovis prevalence was also higher among badgers whose genetic profiles suggested that they had immigrated into their assigned social groups. 4. The association between high M. bovis prevalence and small badger group size appeared not to have been caused by previous small-scale culling in study areas, which had been suspended, on average, 5 years before the start of the current study. 5. The observed pattern of prevalence might occur through badgers in smaller groups interacting more frequently with members of neighbouring groups; detailed behavioural data are needed to test this hypothesis. Likewise, longitudinal data are needed to determine whether the size of infected groups might be suppressed by disease-related mortality. 6. Although M. bovis prevalence was lower at high population densities, the absolute number of infected badgers was higher. However, this does not necessarily mean that the risk of M. bovis transmission to cattle is highest at high badger densities, since transmission risk depends on badger behaviour as well as on badger density.

  6. Root Respiration and Growth in Plantago major as Affected by Vesicular-Arbuscular Mycorrhizal Infection.

    PubMed

    Baas, R; van der Werf, A; Lambers, H

    1989-09-01

    Effects of vesicular-arbuscular mycorrhizal (VAM) infection and P on root respiration and dry matter allocation were studied in Plantago major L. ssp. pleiosperma (Pilger). By applying P, the relative growth rate of non-VAM controls and plants colonized by Glomus fasciculatum (Thaxt. sensu Gerdemann) Gerdemann and Trappe was increased to a similar extent (55-67%). However, leaf area ratio was increased more and net assimilation rate per unit leaf area was increased less by VAM infection than by P addition. The lower net assimilation rate could be related to a 20 to 30% higher root respiration rate per unit leaf area of VAM plants. Root respiration per unit dry matter and specific net uptake rates of N and P were increased more by VAM infection than by P addition. Neither the contribution of the alternative respiratory path nor the relative growth rate could account for the differences in root respiration rate between VAM and non-VAM plants. It was estimated that increased fungal respiration (87%) and ion uptake rate (13%) contributed to the higher respiratory activity of VAM roots of P. major.

  7. Dynamics of the "popcorn" Wolbachia infection in outbred Aedes aegypti informs prospects for mosquito vector control.

    PubMed

    Yeap, H L; Mee, P; Walker, T; Weeks, A R; O'Neill, S L; Johnson, P; Ritchie, S A; Richardson, K M; Doig, C; Endersby, N M; Hoffmann, A A

    2011-02-01

    Forty percent of the world's population is at risk of contracting dengue virus, which produces dengue fever with a potentially fatal hemorrhagic form. The wMelPop Wolbachia infection of Drosophila melanogaster reduces life span and interferes with viral transmission when introduced into the mosquito Aedes aegypti, the primary vector of dengue virus. Wolbachia has been proposed as an agent for preventing transmission of dengue virus. Population invasion by Wolbachia depends on levels of cytoplasmic incompatibility, fitness effects, and maternal transmission. Here we characterized these traits in an outbred genetic background of a potential target population of Ae. aegypti using two crossing schemes. Cytoplasmic incompatibility was strong in this background, and the maternal transmission rate of Wolbachia was high. The infection substantially reduced longevity of infected adult females, regardless of whether adults came from larvae cultured under high or low levels of nutrition or density. The infection reduced the viability of diapausing and nondiapausing eggs. Viability was particularly low when eggs were laid by older females and when diapausing eggs had been stored for a few weeks. The infection affected mosquito larval development time and adult body size under different larval nutrition levels and densities. The results were used to assess the potential for wMelPop-CLA to invade natural populations of Ae. aegypti and to develop recommendations for the maintenance of fitness in infected mosquitoes that need to compete against field insects. PMID:21135075

  8. Dynamics of bovine intramammary infections due to coagulase-negative staphylococci on four farms.

    PubMed

    Bexiga, Ricardo; Rato, Márcia G; Lemsaddek, Abdelhak; Semedo-Lemsaddek, Teresa; Carneiro, Carla; Pereira, Helena; Mellor, Dominic J; Ellis, Kathryn A; Vilela, Cristina L

    2014-05-01

    The objectives of this study were to compare the impact of different coagulase-negative species (CNS) on udder health measured in terms of individual quarter milk somatic cell count (SCC) and duration of intramammary infection, and to get some insight into most likely routes of infection for different CNS species. This longitudinal observational study was performed on four farms that were sampled at 4-week intervals for a total of 12 visits each. Quarters infected with CNS were followed through time with milk samples being submitted for bacteriological culture and SCC determination. PCR amplification of the internal transcribed spacer region and sequencing of the sodA and rpoB genes were used for species allocation. Pulsed-field gel electrophoresis (PFGE) was performed to assess strain identity. The percentage of quarters affected per farm varied between 6 and 35%, with the most frequently isolated CNS species being Staphylococcus epidermidis, followed by Staph. simulans, Staph. chromogenes and Staph. haemolyticus. It was possible to follow 111 intramammary infections due to CNS through time. Duration of infection had a mean of 188 d and was not significantly different between CNS species. Geometric mean quarter SCC overall was 132 000 cells/ml and was also not significantly different between CNS species. Despite the possibility of a different epidemiology of infection, the impact in terms of udder health seems to be similar for different CNS species. PMID:24594229

  9. Infection.

    PubMed

    Miclau, Theodore; Schmidt, Andrew H; Wenke, Joseph C; Webb, Lawrence X; Harro, Janette M; Prabhakara, Ranjani; Shirtliff, Mark E

    2010-09-01

    Musculoskeletal infection is a clinical problem with significant direct healthcare costs. The prevalence of infection after closed, elective surgery is frequently estimated to be less than 2%, but in severe injuries, posttraumatic infection rates have been reported as 10% or greater. Although clinical infections are found outside the realm of medical devices, it is clear that the enormous increase of infections associated with the use of implants presents a major challenge worldwide. This review summarizes recent advances in the understanding, diagnosis, and treatment of musculoskeletal infections.

  10. A mathematical modelling framework for linked within-host and between-host dynamics for infections with free-living pathogens in the environment.

    PubMed

    Garira, Winston; Mathebula, Dephney; Netshikweta, Rendani

    2014-10-01

    In this study we develop a mathematical modelling framework for linking the within-host and between-host dynamics of infections with free-living pathogens in the environment. The resulting linked models are sometimes called immuno-epidemiological models. However, there is still no generalised framework for linking the within-host and between-host dynamics of infectious diseases. Furthermore, for infections with free-living pathogens in the environment, there is an additional stumbling block in that there is a gap in knowledge on how environmental factors (through water, air, soil, food, fomites, etc.) alter many aspects of such infections including susceptibility to infective dose, persistence of infection, pathogen shedding and severity of the disease. In this work, we link the two subsystems (within-host and between-host models) by identifying the within-host and between-host variables and parameters associated with the environmental dynamics of the pathogen and then design a feedback of the variables and parameters across the within-host and between-host models using human schistosomiasis as a case study. We study the mathematical properties of the linked model and show that the model is epidemiologically well-posed. Using results from the analysis of the endemic equilibrium expression, the disease reproductive number R0, and numerical simulations of the full model, we adequately account for the reciprocal influence of the linked within-host and between-host models. In particular, we illustrate that for human schistosomiasis, the outcome of infection at the individual level determines if, when and how much the individual host will further transmit the infectious agent into the environment, eventually affecting the spread of the infection in the host population. We expect the conceptual modelling framework developed here to be applicable to many infectious disease with free-living pathogens in the environment beyond the specific disease system of human

  11. Multistate modeling of habitat dynamics: Factors affecting Florida scrub transition probabilities

    USGS Publications Warehouse

    Breininger, D.R.; Nichols, J.D.; Duncan, B.W.; Stolen, Eric D.; Carter, G.M.; Hunt, D.K.; Drese, J.H.

    2010-01-01

    Many ecosystems are influenced by disturbances that create specific successional states and habitat structures that species need to persist. Estimating transition probabilities between habitat states and modeling the factors that influence such transitions have many applications for investigating and managing disturbance-prone ecosystems. We identify the correspondence between multistate capture-recapture models and Markov models of habitat dynamics. We exploit this correspondence by fitting and comparing competing models of different ecological covariates affecting habitat transition probabilities in Florida scrub and flatwoods, a habitat important to many unique plants and animals. We subdivided a large scrub and flatwoods ecosystem along central Florida's Atlantic coast into 10-ha grid cells, which approximated average territory size of the threatened Florida Scrub-Jay (Aphelocoma coerulescens), a management indicator species. We used 1.0-m resolution aerial imagery for 1994, 1999, and 2004 to classify grid cells into four habitat quality states that were directly related to Florida Scrub-Jay source-sink dynamics and management decision making. Results showed that static site features related to fire propagation (vegetation type, edges) and temporally varying disturbances (fires, mechanical cutting) best explained transition probabilities. Results indicated that much of the scrub and flatwoods ecosystem was resistant to moving from a degraded state to a desired state without mechanical cutting, an expensive restoration tool. We used habitat models parameterized with the estimated transition probabilities to investigate the consequences of alternative management scenarios on future habitat dynamics. We recommend this multistate modeling approach as being broadly applicable for studying ecosystem, land cover, or habitat dynamics. The approach provides maximum-likelihood estimates of transition parameters, including precision measures, and can be used to assess

  12. A systematic review of measures of HIV/AIDS stigma in paediatric HIV-infected and HIV-affected populations

    PubMed Central

    McAteer, Carole Ian; Truong, Nhan-Ai Thi; Aluoch, Josephine; Deathe, Andrew Roland; Nyandiko, Winstone M; Marete, Irene; Vreeman, Rachel Christine

    2016-01-01

    Introduction HIV-related stigma impacts the quality of life and care management of HIV-infected and HIV-affected individuals, but how we measure stigma and its impact on children and adolescents has less often been described. Methods We conducted a systematic review of studies that measured HIV-related stigma with a quantitative tool in paediatric HIV-infected and HIV-affected populations. Results and discussion Varying measures have been used to assess stigma in paediatric populations, with most studies utilizing the full or variant form of the HIV Stigma Scale that has been validated in adult populations and utilized with paediatric populations in Africa, Asia and the United States. Other common measures included the Perceived Public Stigma Against Children Affected by HIV, primarily utilized and validated in China. Few studies implored item validation techniques with the population of interest, although scales were used in a different cultural context from the origin of the scale. Conclusions Many stigma measures have been used to assess HIV stigma in paediatric populations, globally, but few have implored methods for cultural adaptation and content validity. PMID:27717409

  13. Major histocompatibility complex selection dynamics in pathogen-infected túngara frog (Physalaemus pustulosus) populations.

    PubMed

    Kosch, Tiffany A; Bataille, Arnaud; Didinger, Chelsea; Eimes, John A; Rodríguez-Brenes, Sofia; Ryan, Michael J; Waldman, Bruce

    2016-08-01

    Pathogen-driven selection can favour major histocompatibility complex (MHC) alleles that confer immunological resistance to specific diseases. However, strong directional selection should deplete genetic variation necessary for robust immune function in the absence of balancing selection or challenges presented by other pathogens. We examined selection dynamics at one MHC class II (MHC-II) locus across Panamanian populations of the túngara frog, Physalaemus pustulosus, infected by the amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd). We compared MHC-II diversity in highland túngara frog populations, where amphibian communities have experienced declines owing to Bd, with those in the lowland region that have shown no evidence of decline. Highland region frogs had MHC variants that confer resistance to Bd. Variant fixation appeared to occur by directional selection rather than inbreeding, as overall genetic variation persisted in populations. In Bd-infected lowland sites, however, selective advantage may accrue to individuals with only one Bd-resistance allele, which were more frequent. Environmental conditions in lowlands should be less favourable for Bd infection, which may reduce selection for specific Bd resistance in hosts. Our results suggest that MHC selection dynamics fluctuate in túngara frog populations as a function of the favourability of habitat to pathogen spread and the vulnerability of hosts to infection. PMID:27531158

  14. Environmental temperature affects the dynamics of ingestion in the nectivorous ant Camponotus mus.

    PubMed

    Falibene, Agustina; Josens, Roxana

    2014-12-01

    Environmental temperature influences physiology and behavior in animals in general and is particularly determinant in ectotherms. Not least because temperature defines metabolism and body temperature, muscle activity in insects also strongly depends on this factor. Here, we analyzed how environmental temperature influences the dynamics of ingestion due to its effect on the sucking pump muscles in the nectivorous ants Camponotus mus. Feeding behavior and sucking pump activity during sucrose solution ingestion were first recorded in a natural environment in an urban setting throughout the day and in different seasons. Then, controlled temperature experiments were performed in the laboratory. In both situations, feeding time decreased and pumping frequency increased with temperature. However, different pumping frequencies under a same temperature were also observed in different seasons. Besides, in the laboratory, the volume of solution ingested increased with temperature. Consequently, intake rate increased when temperature rose. This change was exclusively promoted by a variation in the pumping frequency while volume taken in per pump contraction was not affected by temperature. In summary, environmental temperature modified the dynamics of ingestion and feeding behavior by directly affecting pumping frequency.

  15. Focal Point Theory Models for Dissecting Dynamic Duality Problems of Microbial Infections

    PubMed Central

    Huang, S.-H.; Zhou, W.; Jong, A.

    2008-01-01

    Extending along the dynamic continuum from conflict to cooperation, microbial infections always involve symbiosis (Sym) and pathogenesis (Pat). There exists a dynamic Sym-Pat duality (DSPD) in microbial infection that is the most fundamental problem in infectomics. DSPD is encoded by the genomes of both the microbes and their hosts. Three focal point (FP) theory-based game models (pure cooperative, dilemma, and pure conflict) are proposed for resolving those problems. Our health is associated with the dynamic interactions of three microbial communities (nonpathogenic microbiota (NP) (Cooperation), conditional pathogens (CP) (Dilemma), and unconditional pathogens (UP) (Conflict)) with the hosts at different health statuses. Sym and Pat can be quantitated by measuring symbiotic index (SI), which is quantitative fitness for the symbiotic partnership, and pathogenic index (PI), which is quantitative damage to the symbiotic partnership, respectively. Symbiotic point (SP), which bears analogy to FP, is a function of SI and PI. SP-converting and specific pathogen-targeting strategies can be used for the rational control of microbial infections. PMID:18350122

  16. A systematic review examining whether interventions are effective in reducing cognitive delay in children infected and affected with HIV.

    PubMed

    Sherr, Lorraine; Croome, Natasha; Bradshaw, Katie; Parra Castaneda, Katherine

    2014-01-01

    Cognitive delay has been recorded in children infected and affected by HIV. This finding is well established, yet few countries report provision of special educational interventions for this group of children. The general rehabilitation literature describes an array of effective interventions for children with learning difficulties. These have rarely been adapted for children affected by HIV, despite their growing numbers. A systematic review was conducted to examine effective interventions for cognitive delay in children (under 18 years) infected with HIV and/or exposed to HIV (HIV-negative child born to an HIV-positive mother). A keyword search of electronic databases with reference follow-up generated 1745 hits. These abstracts were screened for relevance, resulting in 17 papers available for shortlisting. Studies were then included if they were randomised control trials, were longitudinal, pre/post or cohort studies and presented empirical data on an intervention for children infected by HIV or exposed to HIV and had at least one cognitive measure. Carer interventions were included if they had at least one child cognitive measure. Of the 17 papers, 4 met the inclusion criteria based on design and quality. Interventions included cognitive rehearsal, home-based stimulation and parental support. All four interventions showed at least one significant child improvement at follow-up. Despite such improvements, many children still scored within the disability range at follow-up. These results show that the effective interventions are available and should be scaled up to meet the needs of children. Complex interventions are not sufficiently studied. This review suggests an ongoing need to build evidence-based interventions, but calls on evidence-based programmes to be initiated for HIV-positive and HIV-affected children. PMID:24720704

  17. Verticillium longisporum Infection Affects the Leaf Apoplastic Proteome, Metabolome, and Cell Wall Properties in Arabidopsis thaliana

    PubMed Central

    Floerl, Saskia; Majcherczyk, Andrzej; Possienke, Mareike; Feussner, Kirstin; Tappe, Hella; Gatz, Christiane; Feussner, Ivo; Kües, Ursula; Polle, Andrea

    2012-01-01

    Verticillium longisporum (VL) is one of the most devastating diseases in important oil crops from the family of Brassicaceae. The fungus resides for much time of its life cycle in the extracellular fluid of the vascular system, where it cannot be controlled by conventional fungicides. To obtain insights into the biology of VL-plant interaction in the apoplast, the secretome consisting of the extracellular proteome and metabolome as well as cell wall properties were studied in the model Brassicaceae, Arabidopsis thaliana. VL infection resulted in increased production of cell wall material with an altered composition of carbohydrate polymers and increased lignification. The abundance of several hundred soluble metabolites changed in the apoplast of VL-infected plants including signalling and defence compounds such as glycosides of salicylic acid, lignans and dihydroxybenzoic acid as well as oxylipins. The extracellular proteome of healthy leaves was enriched in antifungal proteins. VL caused specific increases in six apoplast proteins (three peroxidases PRX52, PRX34, P37, serine carboxypeptidase SCPL20, α-galactosidase AGAL2 and a germin-like protein GLP3), which have functions in defence and cell wall modification. The abundance of a lectin-like, chitin-inducible protein (CILLP) was reduced. Since the transcript levels of most of the induced proteins were not elevated until late infection time points (>20 dpi), whereas those of CILLP and GLP3 were reduced at earlier time points, our results may suggest that VL enhances its virulence by rapid down-regulation and delay of induction of plant defence genes. PMID:22363647

  18. How predation risk affects the temporal dynamics of avian leks: greater sage grouse versus golden eagles.

    PubMed

    Boyko, Adam R

    2004-01-01

    Leks often attract predators as well as mates, yet most evolutionary models have assumed that sexual selection, not predation, drives lekking behavior. We explored the influence of predation on lek dynamics using a stochastic dynamic game model based on the lek-breeding greater sage grouse (Centrocercus urophasianus) and its principal avian predator, the golden eagle (Aquila chrysaetos). The model predicts time-dependent male lek attendance as a function of factors affecting both mating success (female arrival rate, male numbers, and social status) and predation risk (eagle arrival rate and group size). Dominant males are predicted to arrive sooner and leave later than subordinates, especially if mating skew is high, predation risk is low, or the relationship between lek size and female arrival rate is weak. Both high mean levels of predation risk and small lek size should reduce lek attendance, but the relative tendency of predators to attack large versus small leks has little influence on predicted lekking behavior. Field observations confirmed the predicted effects of female arrival rate, lek size, male dominance, and weather-dependent predator arrival rates on lek departure times. Predicted effects of female arrival rates and male dominance on seasonal lek attendance were also supported. Our model provides an empirically supported adaptive explanation for short-term lek dynamics. It also suggests alternative interpretations for phenomena previously invoked to support the hotshot and skew models of lek formation.

  19. How predation risk affects the temporal dynamics of avian leks: greater sage grouse versus golden eagles.

    PubMed

    Boyko, Adam R

    2004-01-01

    Leks often attract predators as well as mates, yet most evolutionary models have assumed that sexual selection, not predation, drives lekking behavior. We explored the influence of predation on lek dynamics using a stochastic dynamic game model based on the lek-breeding greater sage grouse (Centrocercus urophasianus) and its principal avian predator, the golden eagle (Aquila chrysaetos). The model predicts time-dependent male lek attendance as a function of factors affecting both mating success (female arrival rate, male numbers, and social status) and predation risk (eagle arrival rate and group size). Dominant males are predicted to arrive sooner and leave later than subordinates, especially if mating skew is high, predation risk is low, or the relationship between lek size and female arrival rate is weak. Both high mean levels of predation risk and small lek size should reduce lek attendance, but the relative tendency of predators to attack large versus small leks has little influence on predicted lekking behavior. Field observations confirmed the predicted effects of female arrival rate, lek size, male dominance, and weather-dependent predator arrival rates on lek departure times. Predicted effects of female arrival rates and male dominance on seasonal lek attendance were also supported. Our model provides an empirically supported adaptive explanation for short-term lek dynamics. It also suggests alternative interpretations for phenomena previously invoked to support the hotshot and skew models of lek formation. PMID:14767844

  20. Can ocean acidification affect population dynamics of the barnacle Semibalanus balanoides at its southern range edge?

    PubMed

    Findlay, Helen S; Burrows, Michael T; Kendall, Michael A; Spicer, John I; Widdicombe, Stephen

    2010-10-01

    The global ocean and atmosphere are warming. There is increasing evidence suggesting that, in addition to other environmental factors, climate change is affecting species distributions and local population dynamics. Additionally, as a consequence of the growing levels of atmospheric carbon dioxide (CO2), the oceans are taking up increasing amounts of this CO2, causing ocean pH to decrease (ocean acidification). The relative impacts of ocean acidification on population dynamics have yet to be investigated, despite many studies indicating that there will be at least a sublethal impact on many marine organisms, particularly key calcifying organisms. Using empirical data, we forced a barnacle (Semibalanus balanoides) population model to investigate the relative influence of sea surface temperature (SST) and ocean acidification on a population nearing the southern limit of its geographic distribution. Hindcast models were compared to observational data from Cellar Beach (southwestern United Kingdom). Results indicate that a declining pH trend (-0.0017 unit/yr), indicative of ocean acidification over the past 50 years, does not cause an observable impact on the population abundance relative to changes caused by fluctuations in temperature. Below the critical temperature (here T(crit) = 13.1 degrees C), pH has a more significant affect on population dynamics at this southern range edge. However, above this value, SST has the overriding influence. At lower SST, a decrease in pH (according to the National Bureau of Standards, pHNBs) from 8.2 to 7.8 can significantly decrease the population abundance. The lethal impacts of ocean acidification observed in experiments on early life stages reduce cumulative survival by approximately 25%, which again will significantly alter the population level at this southern limit. Furthermore, forecast predictions from this model suggest that combined acidification and warming cause this local population to die out 10 years earlier than

  1. Decreased summer drought affects plant productivity and soil carbon dynamics in a Mediterranean woodland

    NASA Astrophysics Data System (ADS)

    Cotrufo, M. F.; Alberti, G.; Inglima, I.; Marjanović, H.; Lecain, D.; Zaldei, A.; Peressotti, A.; Miglietta, F.

    2011-09-01

    Precipitation patterns are expected to change in the Mediterranean region within the next decades, with projected decreases in total rainfall and increases in extreme events. We manipulated precipitation patterns in a Mediterranean woodland, dominated by Arbutus unedo L., to study the effects of changing precipitation regimes on above-ground net primary production (ANPP) and soil C dynamics, specifically plant-derived C input to soil and soil respiration (SR). Experimental plots were exposed to either a 20 % reduction of throughfall or to water addition targeted at maintaining soil water content above a minimum of 10 % v/v. Treatments were compared to control plots which received ambient precipitation. Enhanced soil moisture during summer months highly stimulated annual stem primary production, litter fall, SR and net annual plant-derived C input to soil which on average increased by 130 %, 26 %, 58 % and 220 %, respectively, as compared to the control. In contrast, the 20 % reduction in throughfall (equivalent to 10 % reduction in precipitation) did not significantly change soil moisture at the site, and therefore did not significantly affect ANPP or SR. We conclude that minor changes (around 10 % reduction) in precipitation amount are not likely to significantly affect ANPP or soil C dynamics in Mediterranean woodlands. However, if summer rain increases, C cycling will significantly accelerate but soil C stocks are not likely to be changed in the short-term. More studies involving modelling of long-term C dynamics are needed to predict if the estimated increases in soil C input under wet conditions is going to be sustained and if labile C is being substituted to stable C, with a negative effect on long-term soil C stocks.

  2. Decreased summer drought affects plant productivity and soil carbon dynamics in Mediterranean woodland

    NASA Astrophysics Data System (ADS)

    Cotrufo, M. F.; Alberti, G.; Inglima, I.; Marjanović, H.; Lecain, D.; Zaldei, A.; Peressotti, A.; Miglietta, F.

    2011-06-01

    Precipitation patterns are expected to change in the Mediterranean region within the next decades, with projected decreases in total rainfall and increases in extreme events. We manipulated precipitation patterns in a Mediterranean woodland, dominated by Arbutus unedo L., to study the effects of changing precipitation regimes on above-ground net primary production (ANPP) and soil C dynamics, specifically plant-derived C input to soil and soil respiration (SR). Experimental plots were exposed to either a 20 % reduction of throughfall or to water addition targeted at maintaining soil water content above a minimum of 10 % v/v. Treatments were compared to control plots which received ambient precipitation. The throughfall manipulation experiment started in 2004 and we report data up to the 2009 growing season. Enhanced soil moisture during summer months highly stimulated annual stem primary production, litter fall, SR and net annual plant-derived C input to soil which on average increased by 130 %, 26 %, 50 % and 220 %, respectively, as compared to control. In contrast, the 20 % reduction in throughfall (equivalent to 10 % reduction of precipitation) did not significantly change soil moisture at the site, and therefore did not significantly affect ANPP or SR. We conclude that minor changes (around 10 % reduction) in precipitation amount are not likely to significantly affect ANPP or soil C dynamics in Mediterranean woodland. However, if summer rain increases, C cycling will significantly accelerate but soil C stocks are not likely to be changed in the short-term. More studies involving modelling of long term C dynamics are needed to predict if the estimated increases in soil C input under wet conditions is going to be sustained and if labile C is being substituted to stable C, with a negative effect on long term soil C stocks.

  3. Dynamic properties of blood flow and leukocyte mobilization in infected flaps

    SciTech Connect

    Feng, L.J.; Price, D.C.; Mathes, S.J.; Hohn, D. )

    1990-11-01

    Two aspects of the inflammatory response to infection--blood flow alteration and leukocyte mobilization--are investigated in the canine model. The elevation of paired musculocutaneous (MC) and random pattern (RP) flaps allowed comparison of healing flaps with significant differences in blood flow (lower in random pattern flaps) and resistance to infection (greater in musculocutaneous flaps). Blood flow changes as determined by radioactive xenon washout were compared in normal skin and distal flap skin both after elevation and following bacterial inoculation. Simultaneous use of In-111 labeled leukocytes allowed determination of leukocyte mobilization and subsequent localization in response to flap infection. Blood flow significantly improved in the musculocutaneous flap in response to infection. Although total leukocyte mobilization in the random pattern flap was greater, the leukocytes in the musculocutaneous flap were localized around the site of bacterial inoculation within the dermis. Differences in the dynamic blood flow and leukocyte mobilization may, in part, explain the greater reliability of musculocutaneous flaps when transposed in the presence of infection.

  4. Microbial population dynamics in response to Pectobacterium atrosepticum infection in potato tubers.

    PubMed

    Kõiv, Viia; Roosaare, Märt; Vedler, Eve; Kivistik, Paula Ann; Toppi, Kristel; Schryer, David W; Remm, Maido; Tenson, Tanel; Mäe, Andres

    2015-06-29

    Endophytes are microbes and fungi that live inside plant tissues without damaging the host. Herein we examine the dynamic changes in the endophytic bacterial community in potato (Solanum tuberosum) tuber in response to pathogenic infection by Pectobacterium atrosepticum, which causes soft rot in numerous economically important crops. We quantified community changes using both cultivation and next-generation sequencing of the 16S rRNA gene and found that, despite observing significant variability in both the mass of macerated tissue and structure of the endophytic community between individual potato tubers, P. atrosepticum is always taken over by the endophytes during maceration. 16S rDNA sequencing revealed bacteria from the phyla Proteobacteria, Actinobacteria, Firmicutes, Bacteroidetes, Fusobacteria, Verrucomicrobia, Acidobacteria, TM7, and Deinococcus-Thermus. Prior to infection, Propionibacterium acnes is frequently among the dominant taxa, yet is out competed by relatively few dominant taxa as the infection proceeds. Two days post-infection, the most abundant sequences in macerated potato tissue are Gammaproteobacteria. The most dominant genera are Enterobacter and Pseudomonas. Eight days post-infection, the number of anaerobic pectolytic Clostridia increases, probably due to oxygen depletion. These results demonstrate that the pathogenesis is strictly initiated by the pathogen (sensu stricto) and proceeds with a major contribution from the endophytic community.

  5. Dynamics of connective-tissue localization during chronic Borrelia burgdorferi infection.

    PubMed

    Imai, Denise M; Feng, Sunlian; Hodzic, Emir; Barthold, Stephen W

    2013-08-01

    The etiologic agent of Lyme disease, Borrelia burgdorferi, localizes preferentially in the extracellular matrix during persistence. In chronically infected laboratory mice, there is a direct association between B. burgdorferi and the proteoglycan decorin, which suggests that decorin has a role in defining protective niches for persistent spirochetes. In this study, the tissue colocalization of B. burgdorferi with decorin and the dynamics of borrelial decorin tropism were evaluated during chronic infection. Spirochetes were found to colocalize absolutely with decorin, but not collagen I in chronically infected immunocompetent C3H mice. Passive immunization of infected C3H-scid mice with B. burgdorferi-specific immune serum resulted in the localization of spirochetes in decorin-rich microenvironments, with clearance of spirochetes from decorin-poor microenvironments. In passively immunized C3H-scid mice, tissue spirochete burdens were initially reduced, but increased over time as the B. burgdorferi-specific antibody levels waned. Concurrent repopulation of the previously cleared decorin-poor microenvironments was observed with the rising tissue spirochete burden and declining antibody titer. These findings indicate that the specificity of B. burgdorferi tissue localization during chronic infection is determined by decorin, driven by the borrelia-specific antibody response, and fluctuates with the antibody response. PMID:23797360

  6. Microbial population dynamics in response to Pectobacterium atrosepticum infection in potato tubers

    PubMed Central

    Kõiv, Viia; Roosaare, Märt; Vedler, Eve; Ann Kivistik, Paula; Toppi, Kristel; Schryer, David W.; Remm, Maido; Tenson, Tanel; Mäe, Andres

    2015-01-01

    Endophytes are microbes and fungi that live inside plant tissues without damaging the host. Herein we examine the dynamic changes in the endophytic bacterial community in potato (Solanum tuberosum) tuber in response to pathogenic infection by Pectobacterium atrosepticum, which causes soft rot in numerous economically important crops. We quantified community changes using both cultivation and next-generation sequencing of the 16S rRNA gene and found that, despite observing significant variability in both the mass of macerated tissue and structure of the endophytic community between individual potato tubers, P. atrosepticum is always taken over by the endophytes during maceration. 16S rDNA sequencing revealed bacteria from the phyla Proteobacteria, Actinobacteria, Firmicutes, Bacteroidetes, Fusobacteria, Verrucomicrobia, Acidobacteria, TM7, and Deinococcus-Thermus. Prior to infection, Propionibacterium acnes is frequently among the dominant taxa, yet is out competed by relatively few dominant taxa as the infection proceeds. Two days post-infection, the most abundant sequences in macerated potato tissue are Gammaproteobacteria. The most dominant genera are Enterobacter and Pseudomonas. Eight days post-infection, the number of anaerobic pectolytic Clostridia increases, probably due to oxygen depletion. These results demonstrate that the pathogenesis is strictly initiated by the pathogen (sensu stricto) and proceeds with a major contribution from the endophytic community. PMID:26118792

  7. [Cognitive, affective and behavioral changes in crisis: preventing swine flu infection].

    PubMed

    Oikawa, Haruka; Oikawa, Masanori

    2010-10-01

    Calling attention to potential risks does not always lead to preventative actions. To investigate changes in cognitive, emotional, and behavioral responses towards potential risks, longitudinal studies targeting nonclinical samples of undergraduate students were conducted at 4 time points (April, May, June, and July 2009) during the outbreak of swine flu in 2009, which eventually developed in to a global pandemic. During the course of the study, the risk of swine flu infection for the seventy-nine participants became more and more self-relevant as the situation developed in the news and as their university was temporarily closed off. The results indicate that despite increasing knowledge about the swine flu, the level of anxiety showed steady decrease as the time went by. Similarly, despite the expanding infection around the globe, the level of preventative behavior remained low. Moreover, participants reported perceiving their own risk to be significantly lower than that of average undergraduate students at all time points. These findings indicate that even when potential risks are clearly communicated, too much information, saturated emotions, and optimistic bias may obstruct people from taking appropriate preventative actions.

  8. Dynamics of an HIV Model with Multiple Infection Stages and Treatment with Different Drug Classes.

    PubMed

    Wang, Xia; Song, Xinyu; Tang, Sanyi; Rong, Libin

    2016-02-01

    Highly active antiretroviral therapy can effectively control HIV replication in infected individuals. Some clinical and modeling studies suggested that viral decay dynamics may depend on the inhibited stages of the viral replication cycle. In this paper, we develop a general mathematical model incorporating multiple infection stages and various drug classes that can interfere with specific stages of the viral life cycle. We derive the basic reproductive number and obtain the global stability results of steady states. Using several simple cases of the general model, we study the effect of various drug classes on the dynamics of HIV decay. When drugs are assumed to be 100% effective, drugs acting later in the viral life cycle lead to a faster or more rapid decay in viremia. This is consistent with some patient and experimental data, and also agrees with previous modeling results. When drugs are not 100% effective, the viral decay dynamics are more complicated. Without a second population of long-lived infected cells, the viral load decline can have two phases if drugs act at an intermediate stage of the viral replication cycle. The slopes of viral load decline depend on the drug effectiveness, the death rate of infected cells at different stages, and the transition rate of infected cells from one to the next stage. With a second population of long-lived infected cells, the viral load decline can have three distinct phases, consistent with the observation in patients receiving antiretroviral therapy containing the integrase inhibitor raltegravir. We also fit modeling prediction to patient data under efavirenz (a nonnucleoside reverse-transcriptase inhibitor) and raltegravir treatment. The first-phase viral load decline under raltegravir therapy is longer than that under efavirenz, resulting in a lower viral load at initiation of the second-phase decline in patients taking raltegravir. This explains why patients taking a raltegravir-based therapy were faster to achieve

  9. Dynamics of an HIV Model with Multiple Infection Stages and Treatment with Different Drug Classes.

    PubMed

    Wang, Xia; Song, Xinyu; Tang, Sanyi; Rong, Libin

    2016-02-01

    Highly active antiretroviral therapy can effectively control HIV replication in infected individuals. Some clinical and modeling studies suggested that viral decay dynamics may depend on the inhibited stages of the viral replication cycle. In this paper, we develop a general mathematical model incorporating multiple infection stages and various drug classes that can interfere with specific stages of the viral life cycle. We derive the basic reproductive number and obtain the global stability results of steady states. Using several simple cases of the general model, we study the effect of various drug classes on the dynamics of HIV decay. When drugs are assumed to be 100% effective, drugs acting later in the viral life cycle lead to a faster or more rapid decay in viremia. This is consistent with some patient and experimental data, and also agrees with previous modeling results. When drugs are not 100% effective, the viral decay dynamics are more complicated. Without a second population of long-lived infected cells, the viral load decline can have two phases if drugs act at an intermediate stage of the viral replication cycle. The slopes of viral load decline depend on the drug effectiveness, the death rate of infected cells at different stages, and the transition rate of infected cells from one to the next stage. With a second population of long-lived infected cells, the viral load decline can have three distinct phases, consistent with the observation in patients receiving antiretroviral therapy containing the integrase inhibitor raltegravir. We also fit modeling prediction to patient data under efavirenz (a nonnucleoside reverse-transcriptase inhibitor) and raltegravir treatment. The first-phase viral load decline under raltegravir therapy is longer than that under efavirenz, resulting in a lower viral load at initiation of the second-phase decline in patients taking raltegravir. This explains why patients taking a raltegravir-based therapy were faster to achieve

  10. How fragmentation and corridors affect wind dynamics and seed dispersal in open habitats.

    PubMed

    Damschen, Ellen I; Baker, Dirk V; Bohrer, Gil; Nathan, Ran; Orrock, John L; Turner, Jay R; Brudvig, Lars A; Haddad, Nick M; Levey, Douglas J; Tewksbury, Joshua J

    2014-03-01

    Determining how widespread human-induced changes such as habitat loss, landscape fragmentation, and climate instability affect populations, communities, and ecosystems is one of the most pressing environmental challenges. Critical to this challenge is understanding how these changes are affecting the movement abilities and dispersal trajectories of organisms and what role conservation planning can play in promoting movement among remaining fragments of suitable habitat. Whereas evidence is mounting for how conservation strategies such as corridors impact animal movement, virtually nothing is known for species dispersed by wind, which are often mistakenly assumed to not be limited by dispersal. Here, we combine mechanistic dispersal models, wind measurements, and seed releases in a large-scale experimental landscape to show that habitat corridors affect wind dynamics and seed dispersal by redirecting and bellowing airflow and by increasing the likelihood of seed uplift. Wind direction interacts with landscape orientation to determine when corridors provide connectivity. Our results predict positive impacts of connectivity and patch shape on species richness of wind-dispersed plants, which we empirically illustrate using 12 y of data from our experimental landscapes. We conclude that habitat fragmentation and corridors strongly impact the movement of wind-dispersed species, which has community-level consequences.

  11. Crumbs Affects Protein Dynamics In Anterior Regions Of The Developing Drosophila Embryo

    PubMed Central

    Firmino, João; Tinevez, Jean-Yves; Knust, Elisabeth

    2013-01-01

    Maintenance of apico-basal polarity is essential for epithelial integrity and requires particular reinforcement during tissue morphogenesis, when cells are reorganised, undergo shape changes and remodel their junctions. It is well established that epithelial integrity during morphogenetic processes depends on the dynamic exchange of adherens junction components, but our knowledge on the dynamics of other proteins and their dynamics during these processes is still limited. The early Drosophila embryo is an ideal system to study membrane dynamics during morphogenesis. Here, morphogenetic activities differ along the anterior-posterior axis, with the extending germband showing a high degree of epithelial remodelling. We developed a Fluorescence Recovery After Photobleaching (FRAP) assay with a higher temporal resolution, which allowed the distinction between a fast and a slow component of recovery of membrane proteins during the germband extension stage. We show for the first time that the recovery kinetics of a general membrane marker, SpiderGFP, differs in the anterior and posterior parts of the embryo, which correlates well with the different morphogenetic activities of the respective embryonic regions. Interestingly, absence of crumbs, a polarity regulator essential for epithelial integrity in the Drosophila embryo, decreases the fast component of SpiderGFP and of the apical marker Stranded at Second-Venus specifically in the anterior region. We suggest that the defects in kinetics observed in crumbs mutant embryos are the first signs of tissue instability in this region, explaining the earlier breakdown of the head epidermis in comparison to that of the trunk, and that diffusion in the plasma membrane is affected by the absence of Crumbs. PMID:23555600

  12. Multilevel Dynamic Systems Affecting Introduction of HIV/STI Prevention Innovations among Chinese Women in Sex Work Establishments

    ERIC Educational Resources Information Center

    Weeks, Margaret R.; Li, Jianghong; Liao, Susu; Zhang, Qingning; Dunn, Jennifer; Wang, Yanhong; Jiang, Jingmei

    2013-01-01

    Social and public health scientists are increasingly interested in applying system dynamics theory to improve understanding and to harness the forces of change within complex, multilevel systems that affect community intervention implementation, effects, and sustainability. Building a system dynamics model based on ethnographic case study has the…

  13. Lipophosphoglycans from Leishmania amazonensis Strains Display Immunomodulatory Properties via TLR4 and Do Not Affect Sand Fly Infection.

    PubMed

    Nogueira, Paula M; Assis, Rafael R; Torrecilhas, Ana C; Saraiva, Elvira M; Pessoa, Natália L; Campos, Marco A; Marialva, Eric F; Ríos-Velasquez, Cláudia M; Pessoa, Felipe A; Secundino, Nágila F; Rugani, Jerônimo N; Nieves, Elsa; Turco, Salvatore J; Melo, Maria N; Soares, Rodrigo P

    2016-08-01

    The immunomodulatory properties of lipophosphoglycans (LPG) from New World species of Leishmania have been assessed in Leishmania infantum and Leishmania braziliensis, the causative agents of visceral and cutaneous leishmaniasis, respectively. This glycoconjugate is highly polymorphic among species with variation in sugars that branch off the conserved Gal(β1,4)Man(α1)-PO4 backbone of repeat units. Here, the immunomodulatory activity of LPGs from Leishmania amazonensis, the causative agent of diffuse cutaneous leishmaniasis, was evaluated in two strains from Brazil. One strain (PH8) was originally isolated from the sand fly and the other (Josefa) was isolated from a human case. The ability of purified LPGs from both strains was investigated during in vitro interaction with peritoneal murine macrophages and CHO cells and in vivo infection with Lutzomyia migonei. In peritoneal murine macrophages, the LPGs from both strains activated TLR4. Both LPGs equally activate MAPKs and the NF-κB inhibitor p-IκBα, but were not able to translocate NF-κB. In vivo experiments with sand flies showed that both stains were able to sustain infection in L. migonei. A preliminary biochemical analysis indicates intraspecies variation in the LPG sugar moieties. However, they did not result in different activation profiles of the innate immune system. Also those polymorphisms did not affect infectivity to the sand fly.

  14. Lipophosphoglycans from Leishmania amazonensis Strains Display Immunomodulatory Properties via TLR4 and Do Not Affect Sand Fly Infection

    PubMed Central

    Nogueira, Paula M.; Assis, Rafael R.; Torrecilhas, Ana C.; Saraiva, Elvira M.; Pessoa, Natália L.; Campos, Marco A.; Marialva, Eric F.; Ríos-Velasquez, Cláudia M.; Pessoa, Felipe A.; Secundino, Nágila F.; Rugani, Jerônimo N.; Nieves, Elsa; Turco, Salvatore J.; Melo, Maria N.

    2016-01-01

    The immunomodulatory properties of lipophosphoglycans (LPG) from New World species of Leishmania have been assessed in Leishmania infantum and Leishmania braziliensis, the causative agents of visceral and cutaneous leishmaniasis, respectively. This glycoconjugate is highly polymorphic among species with variation in sugars that branch off the conserved Gal(β1,4)Man(α1)-PO4 backbone of repeat units. Here, the immunomodulatory activity of LPGs from Leishmania amazonensis, the causative agent of diffuse cutaneous leishmaniasis, was evaluated in two strains from Brazil. One strain (PH8) was originally isolated from the sand fly and the other (Josefa) was isolated from a human case. The ability of purified LPGs from both strains was investigated during in vitro interaction with peritoneal murine macrophages and CHO cells and in vivo infection with Lutzomyia migonei. In peritoneal murine macrophages, the LPGs from both strains activated TLR4. Both LPGs equally activate MAPKs and the NF-κB inhibitor p-IκBα, but were not able to translocate NF-κB. In vivo experiments with sand flies showed that both stains were able to sustain infection in L. migonei. A preliminary biochemical analysis indicates intraspecies variation in the LPG sugar moieties. However, they did not result in different activation profiles of the innate immune system. Also those polymorphisms did not affect infectivity to the sand fly. PMID:27508930

  15. An infection of human adenovirus 31 affects the differentiation of preadipocytes into fat cells, its metabolic profile and fat accumulation.

    PubMed

    Bil-Lula, Iwona; Krzywonos-Zawadzka, Anna; Sawicki, Grzegorz; Woźniak, Mieczysław

    2016-03-01

    The primary issue undertaken in this study was to test the hypothesis that preadipocytes would have intrinsically elevated propensity to differentiate into mature adipocytes due to HAdV31 infection. To prove that, the metabolic and molecular mechanisms responsible for HAdV31-induced adipogenesis were examined. 3T3L1 cells (mouse embryonic fibroblast, adipose like cell line) were used as a surrogate model to analyze an increased proliferation, differentiation, and maturation of preadipocytes infected with human adenovirus. An expression of E4orf1, C/EBP-β, PPAR-γ, GAPDH, aP2, LEP, and fatty acid synthase genes, intracellular lipid accumulation as well as cytokine release from the fat cells were assessed. Data showed that HAdV31 increased an expression of C/EBP-β and PPAR-γ genes leading to an enhanced differentiation of preadipocytes into fat cells. Besides, overexpression of GAPDH and fatty acid synthase, and decreased expression of leptin caused an increased accumulation of intracellular lipids. Secretion of TNF-α and IL-6 from HAdV31-infected cells was strongly decreased, leading to unlimited virus replication. The results obtained from this study provided the evidences that HAdV31, likewise previously documented HAdV36, is a subsequent human adenovirus affecting the differentiation and lipid accumulation of 3T3L1 cells.

  16. Lipophosphoglycans from Leishmania amazonensis Strains Display Immunomodulatory Properties via TLR4 and Do Not Affect Sand Fly Infection.

    PubMed

    Nogueira, Paula M; Assis, Rafael R; Torrecilhas, Ana C; Saraiva, Elvira M; Pessoa, Natália L; Campos, Marco A; Marialva, Eric F; Ríos-Velasquez, Cláudia M; Pessoa, Felipe A; Secundino, Nágila F; Rugani, Jerônimo N; Nieves, Elsa; Turco, Salvatore J; Melo, Maria N; Soares, Rodrigo P

    2016-08-01

    The immunomodulatory properties of lipophosphoglycans (LPG) from New World species of Leishmania have been assessed in Leishmania infantum and Leishmania braziliensis, the causative agents of visceral and cutaneous leishmaniasis, respectively. This glycoconjugate is highly polymorphic among species with variation in sugars that branch off the conserved Gal(β1,4)Man(α1)-PO4 backbone of repeat units. Here, the immunomodulatory activity of LPGs from Leishmania amazonensis, the causative agent of diffuse cutaneous leishmaniasis, was evaluated in two strains from Brazil. One strain (PH8) was originally isolated from the sand fly and the other (Josefa) was isolated from a human case. The ability of purified LPGs from both strains was investigated during in vitro interaction with peritoneal murine macrophages and CHO cells and in vivo infection with Lutzomyia migonei. In peritoneal murine macrophages, the LPGs from both strains activated TLR4. Both LPGs equally activate MAPKs and the NF-κB inhibitor p-IκBα, but were not able to translocate NF-κB. In vivo experiments with sand flies showed that both stains were able to sustain infection in L. migonei. A preliminary biochemical analysis indicates intraspecies variation in the LPG sugar moieties. However, they did not result in different activation profiles of the innate immune system. Also those polymorphisms did not affect infectivity to the sand fly. PMID:27508930

  17. Quantification of virus-like particles suggests viral infection in corals affected by Porites tissue loss

    NASA Astrophysics Data System (ADS)

    Lawrence, Scott A.; Davy, Joanne E.; Aeby, Greta S.; Wilson, William H.; Davy, Simon K.

    2014-09-01

    Porites tissue loss is a common disease of Porites compressa on Hawaiian reefs. Despite its prevalence, to date, the aetiological agent of the disease has not been found. The apparent lack of a microbial causative agent in the similar disease Porites bleaching with tissue loss, as well as increasing evidence of viral infections in scleractinian corals and Symbiodinium, led us to hypothesise that a virus may be responsible. Electron microscopy revealed the presence of numerous and varied virus-like particles (VLPs) in healthy and diseased P. compressa colonies. While overall virus numbers were similar in all samples, the abundance of a group of icosahedral VLPs differed significantly between healthy and diseased colonies. While not conclusive, these results suggest that viruses may play a role in this disease, and provide a basis for further studies.

  18. Fungal infection reduces herbivore-induced plant volatiles of maize but does not affect naïve parasitoids.

    PubMed

    Rostás, Michael; Ton, Jurriaan; Mauch-Mani, Brigitte; Turlings, Ted C J

    2006-09-01

    Plants attacked by insects release volatile compounds that attract the herbivores' natural enemies. This so-called indirect defense is plastic and may be affected by an array of biotic and abiotic factors. We investigated the effect of fungal infection as a biotic stress agent on the emission of herbivore-induced volatiles and the possible consequences for the attraction of two parasitoid species. Maize seedlings that were simultaneously attacked by the fungus Setosphaeria turcica and larvae of Spodoptera littoralis emitted a blend of volatiles that was qualitatively similar to the blend emitted by maize that was damaged by only the herbivore, but there was a clear quantitative difference. When simultaneously challenged by fungus and herbivore, the maize plants emitted in total 47% less of the volatiles. Emissions of green leaf volatiles were unaffected. In a six-arm olfactometer, the parasitoids Cotesia marginiventris and Microplitis rufiventris responded equally well to odors of herbivore-damaged and fungus- and herbivore-damaged maize plants. Healthy and fungus-infected plants were not attractive. An additional experiment showed that the performance of S. littoralis caterpillars was not affected by the presence of the pathogen, nor was there an effect on larvae of M. rufiventris developing inside the caterpillars. Our results confirm previous indications that naïve wasps may respond primarily to the green leaf volatiles.

  19. The under-compensatory roll aVOR does not affect dynamic visual acuity.

    PubMed

    Schubert, Michael C; Migliaccio, Americo A; Ng, Tammy W C; Shaikh, Aasef G; Zee, David S

    2012-08-01

    Rotations of the head evoke compensatory reflexive eye rotations in the orbit to stabilize images onto the fovea. In normal humans, the angular vestibulo-ocular reflex (aVOR) gain (eye/head velocity) changes depending on the head rotation plane. For pitch and yaw head rotations, the gain is near unity, but during roll head rotations, the aVOR gain is ∼ 0.7. The purpose of this study was to determine whether this physiological discrepancy affects dynamic visual acuity (DVA)--a functional measure of the aVOR that requires subjects to identify letters of varying acuities during head rotation. We used the scleral search coil technique to measure eye and head velocity during passive DVA testing in yaw, roll, and pitch head impulses in healthy controls and patients with unilateral vestibular hypofunction (UVH). For control subjects, the mean aVOR gain during roll impulses was significantly lower than the mean aVOR gain during yaw and pitch impulses; however, there was no difference in DVA between yaw, roll, or pitch. For subjects with UVH, only aVOR gain during head rotations toward the affected side (yaw) were asymmetric (ipsilesional, 0.32 ± 0.17, vs. contralesional, 0.95 ± 0.05), with no asymmetry during roll or pitch. Similarly, there was a large asymmetry for DVA only during yaw head rotations, with no asymmetry in roll or pitch. Interestingly, DVA during roll toward the affected ear was better than DVA during yaw toward the affected ear--even though the ipsilesional roll aVOR gain was 60 % lower. During roll, the axis of eye rotation remains nearly perpendicular to the fovea, resulting in minimal displacement between the fovea and fixation target image projected onto the back of the eye. For subjects with UVH, the DVA score during passive horizontal impulses is a better indicator of poor gaze stability than during passive roll or pitch.

  20. Environmental Conditions Affect Botrytis cinerea Infection of Mature Grape Berries More Than the Strain or Transposon Genotype.

    PubMed

    Ciliberti, Nicola; Fermaud, Marc; Roudet, Jean; Rossi, Vittorio

    2015-08-01

    Effects of environment, Botrytis cinerea strain, and their interaction on the infection of mature grape berries were investigated. The combined effect of temperature (T) of 15, 20, 25, and 30°C and relative humidity (RH) of 65, 80, 90, and 100% was studied by inoculating berries with mycelium plugs. Regardless of the T, no disease occurred at 65% RH, and both disease incidence and severity increased with increasing RH. The combined effect of T (5 to 30°C) and wetness duration (WD) of 3, 6, 12, 24, and 36 h was studied by inoculating berries with conidia. At WD of 36 h, disease incidence was approximately 75% of affected berries at 20 or 25°C, 50% at 15°C, and 30 to 20% at 30 and 10°C; no infection occurred at 5°C. Under favorable conditions (100% RH or 36 h of WD) and unfavorable conditions (65% RH or 3 h of WD), berry wounding did not significantly affect disease incidence; under moderately favorable conditions (80% RH or 6 to 12 h of WD), disease incidence was approximately 1.5 to 5 times higher in wounded than in intact berries. Our data collectively showed that (i) T and RH or WD were more important than strain for mature berry infection by either mycelium or conidia and (ii) the effect of the environment on the different strains was similar. Two equations were developed describing the combined effect of T and RH, or T and WD, on disease incidence following inoculation by mycelium (R2=0.99) or conidia (R2=0.96), respectively. These equations may be useful in the development of models used to predict and control Botrytis bunch rot during berry ripening. PMID:26218433

  1. The Tripartite Virions of the Brome Mosaic Virus Have Distinct Physical Properties That Affect the Timing of the Infection Process

    PubMed Central

    Vaughan, Robert; Tragesser, Brady; Ni, Peng; Ma, Xiang; Dragnea, Bogdan

    2014-01-01

    ABSTRACT The three subsets of virions that comprise the Brome mosaic virus (BMV) were previously thought to be indistinguishable. This work tested the hypothesis that distinct capsid-RNA interactions in the BMV virions allow different rates of viral RNA release. Several results support distinct interactions between the capsid and the BMV genomic RNAs. First, the deletion of the first eight residues of the BMV coat protein (CP) resulted in the RNA1-containing particles having altered morphologies, while those containing RNA2 were unaffected. Second, subsets of the BMV particles separated by density gradients into a pool enriched for RNA1 (B1) and for RNA2 and RNA3/4 (B2.3/4) were found to have different physiochemical properties. Compared to the B2.3/4 particles, the B1 particles were more sensitive to protease digestion and had greater resistivity to nanoindentation by atomic force microscopy and increased susceptibility to nuclease digestion. Mapping studies showed that portions of the arginine-rich N-terminal tail of the CP could interact with RNA1. Mutational analysis in the putative RNA1-contacting residues severely reduced encapsidation of BMV RNA1 without affecting the encapsidation of RNA2. Finally, during infection of plants, the more easily released RNA1 accumulated to higher levels early in the infection. IMPORTANCE Viruses with genomes packaged in distinct virions could theoretically release the genomes at different times to regulate the timing of gene expression. Using an RNA virus composed of three particles, we demonstrated that the RNA in one of the virions is released more easily than the other two in vitro. The differential RNA release is due to distinct interactions between the viral capsid protein and the RNAs. The ease of RNA release is also correlated with the more rapid accumulation of that RNA in infected plants. Our study identified a novel role for capsid-RNA interactions in the regulation of a viral infection. PMID:24672042

  2. Does consideration of water routing affect simulated water and carbon dynamics in terrestrial ecosystems?

    NASA Astrophysics Data System (ADS)

    Tang, G.; Schneiderman, E. M.; Band, L. E.; Hwang, T.; Pierson, D. C.; Pradhanang, S. M.; Zion, M. S.

    2013-10-01

    The cycling of carbon in terrestrial ecosystems is closely coupled with the cycling of water. An important mechanism connecting ecological and hydrological processes in terrestrial ecosystems is lateral flow of water along landscapes. Few studies, however, have examined explicitly how consideration of water routing affects simulated water and carbon dynamics in terrestrial ecosystems. The objective of this study is to explore how consideration of water routing in a process-based hydroecological model affects simulated water and carbon dynamics. To achieve that end, we rasterized the regional hydroecological simulation systems (RHESSys) and employed the rasterized RHESSys (R-RHESSys) in a forested watershed. We performed and compared two contrasting simulations, one with and another without water routing. We found that R-RHESSys is able to correctly simulate major hydrological and ecological variables regardless of whether water routing is considered. When water routing was neglected, however, soil water table depth and saturation deficit were simulated to be smaller and spatially more homogeneous. As a result, evaporation, forest productivity and soil heterotrophic respiration also were simulated to be spatially more homogeneous compared to simulation with water routing. When averaged for the entire watershed, however, differences in simulated water and carbon fluxes are not significant between the two simulations. Overall, the study demonstrated that consideration of water routing enabled R-RHESSys to better capture our preconception of the spatial patterns of water table depth and saturation deficit across the watershed. Because the spatial pattern of soil moisture is fundamental to water efflux from land to the atmosphere, forest productivity and soil microbial activity, ecosystem and carbon cycle models, therefore, need to explicitly represent water routing in order to accurately quantify the magnitudes and patterns of water and carbon fluxes in terrestrial

  3. Does chronic hepatitis B infection affect the clinical course of acute hepatitis A?

    PubMed

    Shin, Su Rin; Moh, In Ho; Jung, Sung Won; Kim, Jin Bae; Park, Sang Hoon; Kim, Hyoung Su; Jang, Myung Kuk; Lee, Myung Seok

    2013-01-01

    The impact of chronic hepatitis B on the clinical outcome of acute hepatitis A remains controversial. The aim of present study was to evaluate the clinical characteristics of acute hepatitis A in cases with underlying chronic hepatitis B compared to cases of acute hepatitis A alone. Data on 758 patients with acute hepatitis A admitted at two university-affiliated hospitals were reviewed. Patients were classified into three groups: group A, patients with both acute hepatitis A and underlying chronic hepatitis B (n = 27); group B, patients infected by acute hepatitis A alone whose sexes and ages were matched with patients in group A (n  = 54); and group C, patients with acute hepatitis A alone (n = 731). None of the demographic features of group A were significantly different from those of group B or C, except for the proportion of males and body weight, which differed from group C. When comparing to group B, clinical symptoms were more frequent, and higher total bilirubin and lower albumin levels were observed in group A. When comparing to group C, the albumin levels were lower in group A. There were no differences in the duration of hospital stay, occurrence of acute kidney injury, acute liver failure, prolonged cholestasis, or relapsing hepatitis. This study revealed that clinical symptoms and laboratory findings were less favorable for patients with acute hepatitis A and chronic hepatitis B compared to those with acute hepatitis A alone. However, there were no differences in fatal outcomes or serious complications.

  4. Dendritic diameters affect the spatial variability of intracellular calcium dynamics in computer models

    PubMed Central

    Anwar, Haroon; Roome, Christopher J.; Nedelescu, Hermina; Chen, Weiliang; Kuhn, Bernd; De Schutter, Erik

    2014-01-01

    There is growing interest in understanding calcium dynamics in dendrites, both experimentally and computationally. Many processes influence these dynamics, but in dendrites there is a strong contribution of morphology because the peak calcium levels are strongly determined by the surface to volume ratio (SVR) of each branch, which is inversely related to branch diameter. In this study we explore the predicted variance of dendritic calcium concentrations due to local changes in dendrite diameter and how this is affected by the modeling approach used. We investigate this in a model of dendritic calcium spiking in different reconstructions of cerebellar Purkinje cells and in morphological analysis of neocortical and hippocampal pyramidal neurons. We report that many published models neglect diameter-dependent effects on calcium concentration and show how to implement this correctly in the NEURON simulator, both for phenomenological pool based models and for implementations using radial 1D diffusion. More detailed modeling requires simulation of 3D diffusion and we demonstrate that this does not dissipate the local concentration variance due to changes of dendritic diameter. In many cases 1D diffusion of models of calcium buffering give a good approximation provided an increased morphological resolution is implemented. PMID:25100945

  5. A mesocosm experiment of suspended particulate matter dynamics in nutrient- and biomass-affected waters.

    PubMed

    Tang, Fiona H M; Maggi, Federico

    2016-02-01

    An experimental study was conducted to test the hypothesis that the biomass growing after an increase in available nutrient in an aquatic ecosystem affects the flocculation dynamics of suspended particulate matter (SPM). The experiment was carried out in a settling column equipped with a turbulence generating system, a water quality monitoring system, and an automated μPIV system to acquire micro photographs of SPM. Three SPM types were tested combinatorially at five turbulence shear rates, three nutrient concentrations, and three mineral concentrations. Analyses of experimental data showed that nutrient availability together with the presence of biomass increased the SPM size by about 60% at low shear as compared to nutrient- and biomass-free conditions; a lower increase was observed at higher shears. In contrast, only 2% lower fractal (capacity) dimension and nearly invariant settling velocity were observed than in nutrient- and biomass-free conditions. Likewise, SPM size and capacity dimension were found to be insensitive to the SPM concentration. Although limited to nearly homogeneous mineral mixes (kaolinite), these experimental findings not only reject the hypothesis that SPM in natural waters can be dealt with as purely mineral systems in all instances, but also anticipate that SPM dynamics in natural waters increasingly exposed to the threat of anthropogenic nutrient discharge would lead to an increased advective flow of adsorbed chemicals and organic carbon.

  6. A mesocosm experiment of suspended particulate matter dynamics in nutrient- and biomass-affected waters.

    PubMed

    Tang, Fiona H M; Maggi, Federico

    2016-02-01

    An experimental study was conducted to test the hypothesis that the biomass growing after an increase in available nutrient in an aquatic ecosystem affects the flocculation dynamics of suspended particulate matter (SPM). The experiment was carried out in a settling column equipped with a turbulence generating system, a water quality monitoring system, and an automated μPIV system to acquire micro photographs of SPM. Three SPM types were tested combinatorially at five turbulence shear rates, three nutrient concentrations, and three mineral concentrations. Analyses of experimental data showed that nutrient availability together with the presence of biomass increased the SPM size by about 60% at low shear as compared to nutrient- and biomass-free conditions; a lower increase was observed at higher shears. In contrast, only 2% lower fractal (capacity) dimension and nearly invariant settling velocity were observed than in nutrient- and biomass-free conditions. Likewise, SPM size and capacity dimension were found to be insensitive to the SPM concentration. Although limited to nearly homogeneous mineral mixes (kaolinite), these experimental findings not only reject the hypothesis that SPM in natural waters can be dealt with as purely mineral systems in all instances, but also anticipate that SPM dynamics in natural waters increasingly exposed to the threat of anthropogenic nutrient discharge would lead to an increased advective flow of adsorbed chemicals and organic carbon. PMID:26641013

  7. Facial feedback affects valence judgments of dynamic and static emotional expressions.

    PubMed

    Hyniewska, Sylwia; Sato, Wataru

    2015-01-01

    The ability to judge others' emotions is required for the establishment and maintenance of smooth interactions in a community. Several lines of evidence suggest that the attribution of meaning to a face is influenced by the facial actions produced by an observer during the observation of a face. However, empirical studies testing causal relationships between observers' facial actions and emotion judgments have reported mixed findings. This issue was investigated by measuring emotion judgments in terms of valence and arousal dimensions while comparing dynamic vs. static presentations of facial expressions. We presented pictures and videos of facial expressions of anger and happiness. Participants (N = 36) were asked to differentiate between the gender of faces by activating the corrugator supercilii muscle (brow lowering) and zygomaticus major muscle (cheek raising). They were also asked to evaluate the internal states of the stimuli using the affect grid while maintaining the facial action until they finished responding. The cheek raising condition increased the attributed valence scores compared with the brow-lowering condition. This effect of facial actions was observed for static as well as for dynamic facial expressions. These data suggest that facial feedback mechanisms contribute to the judgment of the valence of emotional facial expressions.

  8. Facial feedback affects valence judgments of dynamic and static emotional expressions.

    PubMed

    Hyniewska, Sylwia; Sato, Wataru

    2015-01-01

    The ability to judge others' emotions is required for the establishment and maintenance of smooth interactions in a community. Several lines of evidence suggest that the attribution of meaning to a face is influenced by the facial actions produced by an observer during the observation of a face. However, empirical studies testing causal relationships between observers' facial actions and emotion judgments have reported mixed findings. This issue was investigated by measuring emotion judgments in terms of valence and arousal dimensions while comparing dynamic vs. static presentations of facial expressions. We presented pictures and videos of facial expressions of anger and happiness. Participants (N = 36) were asked to differentiate between the gender of faces by activating the corrugator supercilii muscle (brow lowering) and zygomaticus major muscle (cheek raising). They were also asked to evaluate the internal states of the stimuli using the affect grid while maintaining the facial action until they finished responding. The cheek raising condition increased the attributed valence scores compared with the brow-lowering condition. This effect of facial actions was observed for static as well as for dynamic facial expressions. These data suggest that facial feedback mechanisms contribute to the judgment of the valence of emotional facial expressions. PMID:25852608

  9. Benzene dynamics and biodegradation in alluvial aquifers affected by river fluctuations.

    PubMed

    Batlle-Aguilar, J; Morasch, B; Hunkeler, D; Brouyère, S

    2014-01-01

    The spatial distribution and temporal dynamics of a benzene plume in an alluvial aquifer strongly affected by river fluctuations was studied. Benzene concentrations, aquifer geochemistry datasets, past river morphology, and benzene degradation rates estimated in situ using stable carbon isotope enrichment were analyzed in concert with aquifer heterogeneity and river fluctuations. Geochemistry data demonstrated that benzene biodegradation was on-going under sulfate reducing conditions. Long-term monitoring of hydraulic heads and characterization of the alluvial aquifer formed the basis of a detailed modeled image of aquifer heterogeneity. Hydraulic conductivity was found to strongly correlate with benzene degradation, indicating that low hydraulic conductivity areas are capable of sustaining benzene anaerobic biodegradation provided the electron acceptor (SO4 (2-) ) does not become rate limiting. Modeling results demonstrated that the groundwater flux direction is reversed on annual basis when the river level rises up to 2 m, thereby forcing the infiltration of oxygenated surface water into the aquifer. The mobilization state of metal trace elements such as Zn, Cd, and As present in the aquifer predominantly depended on the strong potential gradient within the plume. However, infiltration of oxygenated water was found to trigger a change from strongly reducing to oxic conditions near the river, causing mobilization of previously immobile metal species and vice versa. MNA appears to be an appropriate remediation strategy in this type of dynamic environment provided that aquifer characterization and targeted monitoring of redox conditions are adequate and electron acceptors remain available until concentrations of toxic compounds reduce to acceptable levels.

  10. What You Believe Travels Differently: Information and Infection Dynamics across Sub-networks

    PubMed Central

    Grim, Patrick; Reade, Christopher; Singer, Daniel J.; Fisher, Steven; Majewicz, Stephen

    2013-01-01

    In order to understand the transmission of a disease across a population we will have to understand not only the dynamics of contact infection but the transfer of health-care beliefs and resulting health-care behaviors across that population. This paper is a first step in that direction, focusing on the contrasting role of linkage or isolation between sub-networks in (a) contact infection and (b) belief transfer. Using both analytical tools and agent-based simulations we show that it is the structure of a network that is primary for predicting contact infection—whether the networks or sub-networks at issue are distributed ring networks or total networks (hubs, wheels, small world, random, or scale-free for example). Measured in terms of time to total infection, degree of linkage between sub-networks plays a minor role. The case of belief is importantly different. Using a simplified model of belief reinforcement, and measuring belief transfer in terms of time to community consensus, we show that degree of linkage between sub-networks plays a major role in social communication of beliefs. Here, in contrast to the case of contract infection, network type turns out to be of relatively minor importance. What you believe travels differently. In a final section we show that the pattern of belief transfer exhibits a classic power law regardless of the type of network involved. PMID:24409006

  11. N dynamics of Inner Mongolia typical steppe as affected by grazing

    NASA Astrophysics Data System (ADS)

    Giese, M.; Gao, Y. Z.; Brueck, H.; Butterbach-Bahl, K.

    2012-04-01

    For large areas of Inner Mongolian semi-arid grasslands, as for many regions of the Eurasian steppe belt, substantial land degradation was reported as a consequence of excessive overgrazing during the last decades. Nitrogen is considered as a key element for ecosystem functions and therefore, a comprehensive analysis of the system's N balance and cycle as affected by land-use change is of fundamental importance to maintain, improve or restore ecosystem services such as forage production, carbon sequestration and diversity conservation. In this comprehensive case study of a Chinese typical steppe, we present an in-depth analysis of N dynamics including the balance of N gains and losses, and N cycling. N pools and fluxes were simultaneously quantified on three grassland sites of contrasting grazing intensity. Our N balances indicated the ungrazed site as N sink with annual net N input of up to 3 g N m-2, mainly due to N input by dust deposition, whereas the heavily grazed site must be considered as N source with net losses of up to 1.7 g m-2. Mayor N losses occurred via dust emissions and excrement export from grazing sites, the latter as a consequence of the common practice of keeping sheep in paddocks overnight. Compared to these fluxes, gaseous N losses, export of animal products (live weight and wool) and biological N2 fixation were of minor relevance. Heavy grazing reduced pool sizes of both topsoil organic N, and above- and belowground biomass N. Furthermore, grazing reduced N fluxes with regard to N uptake, decomposition, gross microbial N turnover, and immobilization. Most N-related processes were more intensive in seasons of higher water availability indicating complex interactions between land-use intensity and climate variability. The projected increase of annual atmospheric N wet deposition and changes in rainfall pattern will likely affect the N sink-source pathways and N flux dynamics, indicating high potential impact of future N enrichment and climate

  12. Global Epidemiology of HIV Infection and Related Syndemics Affecting Transgender People

    PubMed Central

    Scheim, Ayden; Xavier, Jessica; Reisner, Sari; Baral, Stefan

    2016-01-01

    Introduction: Transgender populations have been underrepresented in HIV epidemiologic studies and consequently in HIV prevention, care, and treatment programs. Since 2012, there has been a dramatic increase in research focused on transgender people. Studies highlight the burden of HIV and risk determinants, including intersecting stigmas, as drivers of syndemics among transgender populations. This review synthesizes the most recent global epidemiology of HIV infection and describes current gaps in research and interventions to inform prioritization of HIV research for transgender populations. Methods: A systematic review was conducted of the medical literature published between January 1, 2012 and November 30, 2015. The data focused on HIV prevalence, determinants of risk, and syndemics among transgender populations. Results: Estimates varied dramatically by location and subpopulation. Transfeminine individuals have some of the highest concentrated HIV epidemics in the world with laboratory-confirmed prevalence up to 40%. Data were sparse among trans masculine individuals; however, they suggest potential increased risk for trans masculine men who have sex with men (MSM). No prevalence data were available for transgender people across Sub-Saharan Africa or Eastern Europe/Central Asia. Emerging data consistently support the association of syndemic conditions with HIV risk in transgender populations. Discussion: Addressing syndemic conditions and gender-specific challenges is critical to ensure engagement and retention in HIV prevention by transgender populations. Future research should prioritize: filling knowledge gaps in HIV epidemiology; elucidating how stigma shapes syndemic factors to produce HIV and other deleterious effects on transgender health; and understanding how to effectively implement HIV interventions for transgender people. PMID:27429185

  13. Nodulation of Soybeans as Affected by Half-root Infection with Heterodera glycines

    PubMed Central

    Ko, M. P.; Barker, K. R.; Huang, J.-S.

    1984-01-01

    A split-root technique was applied to soybean, Glycine max (L.) Merr. cv. Lee 68, to characterize the nature of the nodulation suppression by race 1 of the soybean cyst nematode (SCN), Heterodera glycines. Root-halves of each split-root plant were inoculated with Rhizobium japonicum, and one root-half only was inoculated with various numbers of SCN eggs. Nodulation (indicated by nodule number, nodule weights, and ratio of nodule weight to root weight) and nitrogen-fixing capacity (indicated by rate of acetylene reduction) were systemically and variously suppressed on both root-halves of the split-root plant 5 weeks after half-root inoculation with 12,500 SCN eggs. Inoculation with 500 eggs caused this suppression only on the SCN-infected (+NE) root-half; nodulation on the companion uninfected (-NE) root-half was stimulated slightly. The +NE root-halves inoculated with 5,000 eggs were excised at 2-week intervals; nodulation on the remaining -NE root-halves was not different from that of the noninoculated control when measured 6 weeks after the SCN inoculation. Thus, the systemic suppression of nodulation was reversible upon the removal of the SCN. Similarly, application of various levels of KNO₃ to the -NE root-halves of the split-root plant did not alleviate the suppressed nodulation on the companion +NE root-halves, even though plant growth was much improved at certain levels of nitrogen (125 μg N/g soil). This indicated that the localized suppression of nodulation by SCN was caused by factors in addition to poor plant growth. PMID:19295882

  14. Domination-time dynamics in susceptible-infected-susceptible virus competition on networks

    NASA Astrophysics Data System (ADS)

    van de Bovenkamp, Ruud; Kuipers, Fernando; Van Mieghem, Piet

    2014-04-01

    When two viruses compete for healthy nodes in a simple network and both spreading rates are above the epidemic threshold, only one virus will survive. However, if we prevent the viruses from dying out, rich dynamics emerge. When both viruses are identical, one virus always dominates the other, but the dominating and dominated virus alternate. We show in the complete graph that the domination time depends on the total number of infected nodes at the beginning of the domination period and, moreover, that the distribution of the domination time decays exponentially yet slowly. When the viruses differ moderately in strength and/or speed the weaker and/or slower virus can still dominate the other but for a short time. Interestingly, depending on the number of infected nodes at the start of a domination period, being quicker can be a disadvantage.

  15. Domination-time dynamics in susceptible-infected-susceptible virus competition on networks.

    PubMed

    van de Bovenkamp, Ruud; Kuipers, Fernando; Van Mieghem, Piet

    2014-04-01

    When two viruses compete for healthy nodes in a simple network and both spreading rates are above the epidemic threshold, only one virus will survive. However, if we prevent the viruses from dying out, rich dynamics emerge. When both viruses are identical, one virus always dominates the other, but the dominating and dominated virus alternate. We show in the complete graph that the domination time depends on the total number of infected nodes at the beginning of the domination period and, moreover, that the distribution of the domination time decays exponentially yet slowly. When the viruses differ moderately in strength and/or speed the weaker and/or slower virus can still dominate the other but for a short time. Interestingly, depending on the number of infected nodes at the start of a domination period, being quicker can be a disadvantage.

  16. Gas dynamics in eutrophic lake sediments affected by oxygen, nitrate, and sulfate.

    PubMed

    Liikanen, Anu; Flöjt, Laura; Martikainen, Pertti

    2002-01-01

    In many freshwater ecosystems, the contents of NO3- and SO4(2-) have increased, whereas O2 has been depleted due to the increased acid and nutrient loads. These changes may affect carbon turnover and the dynamics of the major greenhouse gases CO2, CH4, and N2O. We studied the effects of O2, NO3-, and SO4(2-) availability on carbon mineralization, and fluxes of CO2, CH4, and N2O in the sediments of hyper-eutrophic Lake Kevätön, Finland. Undisturbed sediment cores from the deep (9 m) and shallow (4 m) profundal were incubated in a laboratory microcosm with oxic and anoxic water flows with NO3- or SO4(2-) concentrations of 0, 30, 100, 300, and 2000 microM. The carbon mineralization rate (i.e., the sum of released CO2-C and CH4-C) was not affected by the oxidants. However, the oxidants did change the pathways of carbon degradation and the release of CH4. All of the oxidants depressed CH4 fluxes in the shallow profundal sediments, which had low organic matter content. In the deep profundal sediments rich in organic matter, the CH4 release was reduced by O2 but was not affected by SO4(2-) (the effect of NO3- was not studied). There was an increase in N2O release as the overlying water NO3- concentration increased. Anoxia and highly elevated NO3- concentrations, associated with eutrophication, increased drastically the global warming potential (GWP) of the sedimentary gases in contrast to the SO4(2-) load, which had only minor effects on the GWP.

  17. Reduced short term adaptation to robot generated dynamic environment in children affected by Cerebral Palsy

    PubMed Central

    2011-01-01

    Background It is known that healthy adults can quickly adapt to a novel dynamic environment, generated by a robotic manipulandum as a structured disturbing force field. We suggest that it may be of clinical interest to evaluate to which extent this kind of motor learning capability is impaired in children affected by cerebal palsy. Methods We adapted the protocol already used with adults, which employs a velocity dependant viscous field, and compared the performance of a group of subjects affected by Cerebral Palsy (CP group, 7 subjects) with a Control group of unimpaired age-matched children. The protocol included a familiarization phase (FA), during which no force was applied, a force field adaptation phase (CF), and a wash-out phase (WO) in which the field was removed. During the CF phase the field was shut down in a number of randomly selected "catch" trials, which were used in order to evaluate the "learning index" for each single subject and the two groups. Lateral deviation, speed and acceleration peaks and average speed were evaluated for each trajectory; a directional analysis was performed in order to inspect the role of the limb's inertial anisotropy in the different experimental phases. Results During the FA phase the movements of the CP subjects were more curved, displaying greater and variable directional error; over the course of the CF phase both groups showed a decreasing trend in the lateral error and an after-effect at the beginning of the wash-out, but the CP group had a non significant adaptation rate and a lower learning index, suggesting that CP subjects have reduced ability to learn to compensate external force. Moreover, a directional analysis of trajectories confirms that the control group is able to better predict the force field by tuning the kinematic features of the movements along different directions in order to account for the inertial anisotropy of arm. Conclusions Spatial abnormalities in children affected by cerebral palsy may be

  18. Brief Report: Macrophage Activation in HIV-2-Infected Patients Is Less Affected by Antiretroviral Treatment-sCD163 in HIV-1, HIV-2, and HIV-1/2 Dually Infected Patients.

    PubMed

    Hønge, Bo L; Andersen, Morten N; Jespersen, Sanne; Medina, Candida; Correira, Faustino G; Jakobsen, Martin R; Laursen, Alex; Erikstrup, Christian; Møller, Holger J; Wejse, Christian

    2016-07-01

    The course of disease among HIV-2, HIV-1, and HIV-1/2 dually infected patients is different. We investigated the macrophage activation marker soluble CD163 (sCD163) dynamics in 212 HIV-1, HIV-2, and HIV-1/2 dually infected patients. There were no differences in sCD163 levels at baseline or during follow-up without antiretroviral therapy (ART). At follow-up on ART, median sCD163 levels were decreased for HIV-1-infected patients (P < 0.001), but not among HIV-2 (P = 0.093) or HIV-1/2 dually infected patients (P = 0.145). The larger decrease in sCD163 levels among HIV-1-infected patients during ART may indicate an HIV type-dependent differential effect of ART on macrophage activation during HIV infection. PMID:26825178

  19. Bioluminescence imaging of chronic Trypanosoma cruzi infections reveals tissue-specific parasite dynamics and heart disease in the absence of locally persistent infection

    PubMed Central

    Lewis, Michael D; Fortes Francisco, Amanda; Taylor, Martin C; Burrell-Saward, Hollie; McLatchie, Alex P; Miles, Michael A; Kelly, John M

    2014-01-01

    Summary Chronic Trypanosoma cruzi infections lead to cardiomyopathy in 20–30% of cases. A causal link between cardiac infection and pathology has been difficult to establish because of a lack of robust methods to detect scarce, focally distributed parasites within tissues. We developed a highly sensitive bioluminescence imaging system based on T. cruzi expressing a novel luciferase that emits tissue-penetrating orange-red light. This enabled long-term serial evaluation of parasite burdens in individual mice with an in vivo limit of detection of significantly less than 1000 parasites. Parasite distributions during chronic infections were highly focal and spatiotemporally dynamic, but did not localize to the heart. End-point ex vivo bioluminescence imaging allowed tissue-specific quantification of parasite loads with minimal sampling bias. During chronic infections, the gastro-intestinal tract, specifically the colon and stomach, was the only site where T. cruzi infection was consistently observed. Quantitative PCR-inferred parasite loads correlated with ex vivo bioluminescence and confirmed the gut as the parasite reservoir. Chronically infected mice developed myocarditis and cardiac fibrosis, despite the absence of locally persistent parasites. These data identify the gut as a permissive niche for long-term T. cruzi infection and show that canonical features of Chagas disease can occur without continual myocardium-specific infection. PMID:24712539

  20. Attempted mathematical models of seasonal dynamics of cestode infections in intermediate and final hosts.

    PubMed

    Yakushev VYu; Freze, V I; Sysoev, A V; Pelgunov, A N; Malkin, A E

    1985-08-01

    The possibility of describing cestode infection dynamics in various host groups (e.g in birds, fishes and copepods) by trigonometric and parabolic polynomials is examined. The necessity of observing certain requirements during data collection for the correct application of the examined models is shown; the possibility of applying a parabolic polynomial in case of non-observing of some of these requirements has been found. The mathematical models obtained are of prognostic value and may serve as a measure of the uniformity and validity of the empirical data. PMID:4061959

  1. Infection dynamics in frog populations with different histories of decline caused by a deadly disease.

    PubMed

    Sapsford, Sarah J; Voordouw, Maarten J; Alford, Ross A; Schwarzkopf, Lin

    2015-12-01

    Pathogens can drive host population dynamics. Chytridiomycosis is a fungal disease of amphibians that is caused by the fungus Batrachochytrium dendrobatidis (Bd). This pathogen has caused declines and extinctions in some host species whereas other host species coexist with Bd without suffering declines. In the early 1990s, Bd extirpated populations of the endangered common mistfrog, Litoria rheocola, at high-elevation sites, while populations of the species persisted at low-elevation sites. Today, populations have reappeared at many high-elevation sites where they presently co-exist with the fungus. We conducted a capture-mark-recapture (CMR) study of six populations of L. rheocola over 1 year, at high and low elevations. We used multistate CMR models to determine which factors (Bd infection status, site type, and season) influenced rates of frog survival, recapture, infection, and recovery from infection. We observed Bd-induced mortality of individual frogs, but did not find any significant effect of Bd infection on the survival rate of L. rheocola at the population level. Survival and recapture rates depended on site type and season. Infection rate was highest in winter when temperatures were favourable for pathogen growth, and differed among site types. The recovery rate was high (75.7-85.8%) across seasons, and did not differ among site types. The coexistence of L. rheocola with Bd suggests that (1) frog populations are becoming resistant to the fungus, (2) Bd may have evolved lower virulence, or (3) current environmental conditions may be inhibiting outbreaks of the fatal disease. PMID:26293680

  2. Infection dynamics in frog populations with different histories of decline caused by a deadly disease.

    PubMed

    Sapsford, Sarah J; Voordouw, Maarten J; Alford, Ross A; Schwarzkopf, Lin

    2015-12-01

    Pathogens can drive host population dynamics. Chytridiomycosis is a fungal disease of amphibians that is caused by the fungus Batrachochytrium dendrobatidis (Bd). This pathogen has caused declines and extinctions in some host species whereas other host species coexist with Bd without suffering declines. In the early 1990s, Bd extirpated populations of the endangered common mistfrog, Litoria rheocola, at high-elevation sites, while populations of the species persisted at low-elevation sites. Today, populations have reappeared at many high-elevation sites where they presently co-exist with the fungus. We conducted a capture-mark-recapture (CMR) study of six populations of L. rheocola over 1 year, at high and low elevations. We used multistate CMR models to determine which factors (Bd infection status, site type, and season) influenced rates of frog survival, recapture, infection, and recovery from infection. We observed Bd-induced mortality of individual frogs, but did not find any significant effect of Bd infection on the survival rate of L. rheocola at the population level. Survival and recapture rates depended on site type and season. Infection rate was highest in winter when temperatures were favourable for pathogen growth, and differed among site types. The recovery rate was high (75.7-85.8%) across seasons, and did not differ among site types. The coexistence of L. rheocola with Bd suggests that (1) frog populations are becoming resistant to the fungus, (2) Bd may have evolved lower virulence, or (3) current environmental conditions may be inhibiting outbreaks of the fatal disease.

  3. Alkaloid Quantities in Endophyte-Infected Tall Fescue are Affected by the Plant-Fungus Combination and Environment.

    PubMed

    Helander, M; Phillips, T; Faeth, S H; Bush, L P; McCulley, R; Saloniemi, I; Saikkonen, K

    2016-02-01

    Many grass species are symbiotic with systemic, vertically-transmitted, asymptomatic Epichloë endophytic fungi. These fungi often produce alkaloids that defend the host against herbivores. We studied how environmental variables affect alkaloids in endophyte-infected tall fescue (Schedonorus phoenix) from three Northern European wild origins and the widely planted US cultivar 'Kentucky-31' (KY31). The plants were grown in identical common garden experiments in Finland and Kentucky for two growing seasons. Plants were left as controls (C) or given water (W), nutrient (N) or water and nutrient (WN) treatments. For 8-10 replications of each plant origin and treatment combination in both experiments, we analyzed ergot alkaloids, lysergic acid, and lolines. In Finland, tall fescue plants produced 50 % more ergot alkaloids compared to plants of the same origin and treatments in Kentucky. Origin of the plants affected the ergot alkaloid concentration at both study sites: the wild origin plants produced 2-4 times more ergot alkaloids than KY31, but the ergot alkaloid concentration of KY31 plants was the same at both locations. Overall lysergic acid content was 60 % higher in plants grown in Kentucky than in those grown in Finland. Nutrient treatments (N, WN) significantly increased ergot alkaloid concentrations in plants from Finland but not in plants from Kentucky. These results suggest that the success of KY31 in US is not due to selection for high ergot alkaloid production but rather other traits associated with the endophyte. In addition, the environmental effects causing variation in alkaloid production of grass-endophyte combinations should be taken into account when using endophyte-infected grasses agriculturally. PMID:26815170

  4. Population dynamics of dechlorinators and factors affecting the level and products of PCB dechlorination in sediments

    SciTech Connect

    Kim, J.S.; Sokol, R.C.; Liu, X.; Bethoney, C.M.; Rhee, G.Y.

    1996-12-31

    Microbial dechlorination of polychlorinated biphenyls (PCBs) often stops although a significant number of removable chlorines remain. To determine the reason for the cessation, we investigated the limitation of organic carbon, PCB bioavailability, and inhibition by metabolic products. Enrichment with carbon sources did not induce additional chlorination, indicating the plateau was not due to depletion of organic carbon. The bioavailability was not limiting, since a subcritical micelle concentration of the surfactant, which enhanced desorption without inhibiting dechlorinating microorganisms, failed to lower the plateau. Neither was it due to accumulation of metabolites, since no additional dechlorination was detected when plateau sediments were incubated with fresh medium. Similarly, dechlorination was not inhibited in freshly spiked sediment slurries. Dechlorination ended up at the same level with nearly identical congener profiles, regardless of treatment. These results indicate that cessation of dechlorination was due to the accumulation of daughter congeners, which cannot be used as electron acceptors by microbes. To determine whether the decreasing availability affected the microorganisms, we determined the population dynamics of dechlorinators using the most probable number technique. The growth dynamics of the dechlorinators mirrored the time course of dechlorination. It started when the population increased by two orders of magnitude. Once dechlorination stopped the dechlorinating population also began to decrease. When dechlorinators were inoculated into PCB-free sediments, the population decreased over time. The decrease of the population as dechlorination ceased confirms that the diminishing availability of congeners was the reason for the incomplete dechlorination. Recent findings have shown that a second phase of dechlorination of certain congeners can occur after a long lag. 45 refs., 8 figs.

  5. Land use affects the resistance and resilience of carbon dynamics of mountain grassland to extreme drought

    NASA Astrophysics Data System (ADS)

    Ingrisch, Johannes; Karlowsky, Stefan; Hasibeder, Roland; Anadon-Rosell, Alba; Augusti, Angela; Scheld, Sarah; König, Alexander; Gleixner, Gerd; Bahn, Michael

    2015-04-01

    Climatic extremes like droughts are expected to occur more frequently and to be more severe in a future climate and have been shown to strongly affect the carbon (C) cycle. Few studies have so far explored how the management intensity of ecosystems and land-use changes alter C cycle responses to extreme climatic events. In many mountain areas land-use changes have been taking place at a rapid pace and have altered plant species composition and biogeochemical cycles. It is still unknown whether and how abandonment of mountain grasslands affects the resistance and the resilience of carbon dynamics to extreme drought. We carried out an in situ experiment to test the hypothesis that abandonment increases the resistance of grassland C dynamics to extreme drought, but decreases its resilience (i.e. post-drought recovery). In a common garden experiment at a mountain meadow in the Austrian Central Alps we exposed large intact monoliths from the meadow and a nearby abandoned grassland to extreme drought conditions during the main growth period in late spring. We measured above- and belowground productivity and net ecosystem exchange and its components over the course of the drought and during the recovery to assess and quantify their resistance and resilience. Furthermore, we analysed the coupling of the two major ecosystem CO2 fluxes, photosynthesis and soil respiration, as based on 13CO2 pulse labelling campaigns at peak drought and during post-drought recovery using isotope laser spectroscopy. Four weeks of early season drought induced a strong decrease of aboveground biomass at the mountain meadow, whereas no effect was observed for the abandoned grassland. At peak drought gross primary productivity was reduced at both grasslands compared to the respective controls, but with a stronger decrease at the meadow (80%) compared to the abandoned grassland (60%). The same pattern was observed for ecosystem respiration. However, the effect was less pronounced compared to carbon

  6. Soil organic matter dynamics under Beech and Hornbeam as affected by soil biological activity

    NASA Astrophysics Data System (ADS)

    Kooijman, A. M.; Cammeraat, L. H.

    2009-04-01

    Organic matter dynamics are highly affected both the soil fauna as well as the source of organic matter, having important consequences for the spatial heterogeneity of organic matter storage and conversion. We studied oldgrowth mixed deciduous forests in Central-Luxemburg on decalcified dolomitic marl, dominated by high-degradable hornbeam (Carpinus betulus L.) or low-degradable beech (Fagus sylvatica L.). Decomposition was measured both in the laboratory and in the field. Litter decomposition was higher for hornbeam than for beech under laboratory conditions, but especially in the field, which is mainly to be attributed to macro-fauna activity, specifically to earthworms (Lumbricus terrestris and Allolobophora species). We also investigated differences between beech and hornbeam with regard to litter input and habitat conditions. Total litter input was the same, but contribution of beech and hornbeam litter clearly differed between the two species. Also, mass of the ectorganic horizon and soil C:N ratio were significantly higher for beech, which was reflected in clear differences in the development of ectorganic profiles on top of the soil. Under beech a mull-moder was clearly present with a well developed fermentation and litter horizon, whereas under hornbeam all litter is incorporated into the soil, leaving the mineral soil surface bear in late summer (mull-type of horizon). In addition to litter quality, litter decomposition was affected by pH and soil moisture. Both pH and soil moisture were higher under hornbeam than under beech, which may reflect differences in soil development and litter quality effects over longer time scales. Under beech, dense layers of low-degradable litter may prevent erosion, and increase clay eluviation and leaching of base cations, leading to acid and dry conditions, which further decrease litter decay. Under hornbeam, the soil is not protected by a litter layer, and clay eluviation and acidification may be counteracted by erosion

  7. Dynamics of Wind-Affected Volcanic Plumes: The Example of the 2011 Cordon Caulle Eruption, Chile

    NASA Astrophysics Data System (ADS)

    Bonadonna, C.; Pistolesi, M.; Cioni, R.; Degruyter, W.; Elissondo, M.; Baumann, V.

    2014-12-01

    The 2011 Cordon Caulle eruption represents an ideal case study for the characterization of long-lasting plumes that are strongly affected by wind. The climactic phase lasted for about one day and was classified as subplinian to small-moderate with plumes between 9-12 km above the vent and Mass Flow Rate (MFR) on the order of 107 kg/s. The first 10 days of the eruption had MFR values >106 kg/s and were followed by several months of low-intensity plumes. Plume dynamics and rise were strongly affected by wind during the whole eruption, with negligible up-wind spreading. Pyroclastic Density Currents (PDCs) due to column collapse were mostly observed on June 4th-5th when wind velocity was lowest and MFR highest, suggesting that PDC generation can be reduced by wind advection. Individual phases of the eruption range between VEI 3-4, while the cumulative deposit associated with June 4th-7th, 2011, is associated with a VEI 5 and a minimum magnitude of 4.8. Crosswind cloud spreading and deposit dispersal of the first few days could be best described by a linear combination of gravitational spreading and turbulent diffusion, with velocities between 1-10 m/s and diffusion coefficients that are consistent with measured values for atmospheric diffusivity. Downwind cloud spreading could be best described by a linear combination of gravitational intrusion and wind advection, with velocities between 17-45 m/s. Our results show how gravitational spreading can be significant even for small-moderate eruptions strongly advected by wind and with relatively low Richardson number and low MFR.

  8. LlSR28 is involved in pollen germination by affecting filamentous actin dynamics.

    PubMed

    Cao, Li-Juan; Zhao, Meng-Meng; Liu, Chang; Dong, Huai-Jian; Li, Wang-Cheng; Ren, Hai-Yun

    2013-07-01

    Alternative splicing plays important roles in gene regulation and contributes to protein complexity. Previous studies suggest that alternative splicing exists in members of the villin/gelsolin/fragmin superfamily. In this study, a serine/argine-rich (SR) protein cDNA with 28 kDa protein (LlSR28) was isolated from a lily (Lilium longiflorum) expression library. Protein domain analysis showed that LlSR28 had similar structures to Arabidopsis SR45 (AtSR45), and LlSR28 could complement the phenotype of loss of AtSR45 function. Therefore, overexpression of LlSR28 and AtSR45 mutant (atsr45-1) were used in the following experiments. Overexpression of LlSR28 in Arabidopsis completely inhibited pollen germination. In contrast, the pollen germination of atsr45-1 was earlier than that of wild-type. In addition, pollen of atsr45-1 contained less F-actin at the corresponding hydration stage during pollen germination compared to that of wild-type. Alternative splicing analysis showed that Arabidopsis villin1 (AtVLN1) transcript encoding the full-length protein was increased, and that encoding the truncated protein was decreased in atst45-1. Moreover, the mRNA expression level of other actin-binding proteins (ABPs) abundant in Arabidopsis pollen was also changed in atsr45-1. In conclusion, we hypothesize that LlSR28 alters F-actin dynamics probably through its alternative splicing activities to affect directly or indirectly the alternative splicing of AtVLN1 and the expression of different ABPs, which then affects the pollen germination. PMID:23741063

  9. Spatiotemporal dynamics of affective picture processing revealed by intracranial high-gamma modulations.

    PubMed

    Boucher, Olivier; D'Hondt, Fabien; Tremblay, Julie; Lepore, Franco; Lassonde, Maryse; Vannasing, Phetsamone; Bouthillier, Alain; Nguyen, Dang Khoa

    2015-01-01

    Our comprehension of the neural mechanisms underlying emotional information processing has largely benefited from noninvasive electrophysiological and functional neuroimaging techniques in recent years. However, the spatiotemporal dynamics of the neural events occurring during emotional processing remain imprecise due to the limited combination of spatial and temporal resolution provided by these techniques. This study examines the modulations of high-frequency activity of intracranial electroencephalography recordings associated with affective picture valence, in epileptic patients awaiting neurosurgery. Recordings were obtained from subdural grids and depth electrodes in eight patients while they viewed a series of unpleasant, pleasant and neutral pictures from the International Affective Picture System. Broadband high-gamma (70-150 Hz) power was computed for separate 100-ms time windows and compared according to ratings of emotional valence. Compared to emotionally neutral or pleasant pictures, unpleasant stimuli were associated with an early and long-lasting (≈200-1,000 ms) bilateral increase in high-gamma activity in visual areas of the occipital and temporal lobes, together with a late and transient (≈500-800 ms) decrease found bilaterally in the lateral prefrontal cortex (PFC). Pleasant pictures were associated with increased gamma activity in the occipital cortex, compared to the emotionally neutral stimuli. Consistent with previous studies, our results provide direct evidence of emotion-related modulations in the visual ventral pathway during picture processing. Results in the lateral PFC also shed light on the neural mechanisms underlying its role in negative emotions processing. This study demonstrates the utility of intracranial high-gamma modulations to study emotional process with a high spatiotemporal precision.

  10. Infection.

    PubMed

    Saigal, Gaurav; Nagornaya, Natalya; Post, M Judith D

    2016-01-01

    Imaging is useful in the diagnosis and management of infections of the central nervous system. Typically, imaging findings at the outset of the disease are subtle and nonspecific, but they often evolve to more definite imaging patterns in a few days, with less rapidity than for stroke but faster than for neoplastic lesions. This timing is similar to that of noninfectious inflammatory brain disease, such as multiple sclerosis. Fortunately, imaging patterns help to distinguish the two kinds of processes. Other than for sarcoidosis, the meninges are seldom involved in noninfectious inflammation; in contrast, many infectious processes involve the meninges, which then enhance with contrast on computed tomography (CT) or magnetic resonance imaging (MRI). However, brain infection causes a vast array of imaging patterns. Although CT is useful when hemorrhage or calcification is suspected or bony detail needs to be determined, MRI is the imaging modality of choice in the investigation of intracranial infections. Imaging sequences such as diffusion-weighted imaging help in accurately depicting the location and characterizing pyogenic infections and are particularly useful in differentiating bacterial infections from other etiologies. Susceptibility-weighted imaging is extremely useful for the detection of hemorrhage. Although MR spectroscopy findings can frequently be nonspecific, certain conditions such as bacterial abscesses show a relatively specific spectral pattern and are useful in diagnosing and constituting immediate therapy. In this chapter we review first the imaging patterns associated with involvement of various brain structures, such as the epidural and subdural spaces, the meninges, the brain parenchyma, and the ventricles. Involvement of these regions is illustrated with bacterial infections. Next we illustrate the patterns associated with viral and prion diseases, followed by mycobacterial and fungal infections, to conclude with a review of imaging findings

  11. Impact of Persistent Cytomegalovirus Infection on Dynamic Changes in Human Immune System Profile

    PubMed Central

    Vescovini, Rosanna; Telera, Anna Rita; Pedrazzoni, Mario; Abbate, Barbara; Rossetti, Pietro; Verzicco, Ignazio; Arcangeletti, Maria Cristina; Medici, Maria Cristina; Calderaro, Adriana; Volpi, Riccardo; Sansoni, Paolo; Fagnoni, Francesco Fausto

    2016-01-01

    Human cytomegalovirus (HCMV) imprints the immune system after primary infection, however its effect during chronic infection still needs to be deciphered. In this study we report the variation of blood cell count along with anti-HCMV IgG and T cell responses to pp-65 and IE-1 antigens, that occurred after an interval of five years in a cohort of 25 seropositive healthy adults. We found increased anti-viral IgG antibody responses and intracellular interferon-gamma secreting CD8+ T cell responses to pp-65: a result consistent with memory inflation. With the only exception of shortage in naive CD8+ T cells most memory T cell subsets as well as total CD8+ T cells, T cells, lymphocytes, monocytes and leukocytes had increased. By contrast, none of the cell types tested were found to have increased in 14 subjects stably seronegative. Rather, in addition to a shortage in naive CD8+ T cells, also memory T cell subsets and most other cell types decreased, either in a statistically significant or non-significant manner. The trend of T cell pool representation with regard to CD4/CD8 ratio was in the opposing directions depending on HCMV serology. Globally, this study demonstrates different dynamic changes of most blood cell types depending on presence or absence of HCMV infection. Therefore, HCMV plays a continual role in modulating homeostasis of blood T cells and a broader expanding effect on other cell populations of lymphoid and myeloid origin. PMID:26990192

  12. Tyrosine crosslinking reveals interfacial dynamics in adeno-associated viral capsids during infection

    PubMed Central

    Horowitz, Eric D.; Finn, M.G.; Asokan, Aravind

    2012-01-01

    Viral capsid dynamics are often observed during infectious events such as cell surface attachment, entry and genome release. Structural analysis of adeno-associated virus (AAV), a helper-dependent parvovirus, revealed a cluster of surface-exposed tyrosine residues at the icosahedral two-fold symmetry axis. We exploited the latter observation to carry out selective oxidation of Tyr residues, which yielded crosslinked viral protein (VP) subunit dimers, effectively “stitching” together the AAV capsid two-fold interface. Characterization of different Tyr-to-Phe mutants confirmed that the formation of crosslinked VP dimers is mediated by dityrosine adducts and requires the Tyr704 residue, which crosses over from one neighboring VP subunit to the other. When compared to unmodified capsids, Tyr-crosslinked AAV displayed decreased transduction efficiency in cell culture. Surprisingly, further biochemical and quantitative microscopy studies revealed that restraining the two-fold interface hinders externalization of buried VP N-termini, which contain a phospholipase A2 domain and nuclear localization sequences critical for infection. These adverse effects caused by tyrosine oxidation support the notion that interfacial dynamics at the AAV capsid two-fold symmetry axis play a role in externalization of VP N-termini during infection. PMID:22458529

  13. Spatiotemporal dynamics of black-tailed prairie dog colonies affected by plague

    USGS Publications Warehouse

    Augustine, D.J.; Matchett, M.R.; Toombs, T.P.; Cully, J.F.; Johnson, T.L.; Sidle, John G.

    2008-01-01

    Black-tailed prairie dogs (Cynomys ludovicianus) are a key component of the disturbance regime in semi-arid grasslands of central North America. Many studies have compared community and ecosystem characteristics on prairie dog colonies to grasslands without prairie dogs, but little is known about landscape-scale patterns of disturbance that prairie dog colony complexes may impose on grasslands over long time periods. We examined spatiotemporal dynamics in two prairie dog colony complexes in southeastern Colorado (Comanche) and northcentral Montana (Phillips County) that have been strongly influenced by plague, and compared them to a complex unaffected by plague in northwestern Nebraska (Oglala). Both plague-affected complexes exhibited substantial spatiotemporal variability in the area occupied during a decade, in contrast to the stability of colonies in the Oglala complex. However, the plague-affected complexes differed in spatial patterns of colony movement. Colonies in the Comanche complex in shortgrass steppe shifted locations over a decade. Only 10% of the area occupied in 1995 was still occupied by prairie dogs in 2006. In 2005 and 2006 respectively, 74 and 83% of the total area of the Comanche complex occurred in locations that were not occupied in 1995, and only 1% of the complex was occupied continuously over a decade. In contrast, prairie dogs in the Phillips County complex in mixed-grass prairie and sagebrush steppe primarily recolonized previously occupied areas after plague-induced colony declines. In Phillips County, 62% of the area occupied in 1993 was also occupied by prairie dogs in 2004, and 12% of the complex was occupied continuously over a decade. Our results indicate that plague accelerates spatiotemporal movement of prairie dog colonies, and have significant implications for landscape-scale effects of prairie dog disturbance on grassland composition and productivity. These findings highlight the need to combine landscape-scale measures of

  14. Bifurcation in Disease Dynamics with Latent Period of Infection and Media Awareness

    NASA Astrophysics Data System (ADS)

    Singh, Harkaran; Dhar, Joydip; Bhatti, Harbax Singh

    2016-06-01

    In the present study, an SIS epidemic model with a latent period of infection and media awareness as control strategy is proposed. The asymptotic stability of the model is studied for both disease-free equilibrium and endemic equilibrium states with respect to the basic reproduction number R0. It is observed that the coefficient of media awareness m does not affect R0, but significantly affects the level of endemic equilibrium. Further, the specific conditions for the existence of Hopf bifurcation have been obtained for the endemic equilibrium state. We also performed the sensitivity analysis of the basic reproduction number and state variables at endemic steady state with respect to the model parameter and identified the respective sensitive parameters. Numerical simulations have been presented in support of our analytic findings.

  15. Seasonal time bombs: dominant temperate viruses affect Southern Ocean microbial dynamics.

    PubMed

    Brum, Jennifer R; Hurwitz, Bonnie L; Schofield, Oscar; Ducklow, Hugh W; Sullivan, Matthew B

    2016-02-01

    Rapid warming in the highly productive western Antarctic Peninsula (WAP) region of the Southern Ocean has affected multiple trophic levels, yet viral influences on microbial processes and ecosystem function remain understudied in the Southern Ocean. Here we use cultivation-independent quantitative ecological and metagenomic assays, combined with new comparative bioinformatic techniques, to investigate double-stranded DNA viruses during the WAP spring-summer transition. This study demonstrates that (i) temperate viruses dominate this region, switching from lysogeny to lytic replication as bacterial production increases, and (ii) Southern Ocean viral assemblages are genetically distinct from lower-latitude assemblages, primarily driven by this temperate viral dominance. This new information suggests fundamentally different virus-host interactions in polar environments, where intense seasonal changes in bacterial production select for temperate viruses because of increased fitness imparted by the ability to switch replication strategies in response to resource availability. Further, temperate viral dominance may provide mechanisms (for example, bacterial mortality resulting from prophage induction) that help explain observed temporal delays between, and lower ratios of, bacterial and primary production in polar versus lower-latitude marine ecosystems. Together these results suggest that temperate virus-host interactions are critical to predicting changes in microbial dynamics brought on by warming in polar marine systems.

  16. On the Role of Global Magnetic Field Configuration in Affecting Ring Current Dynamics

    NASA Technical Reports Server (NTRS)

    Zheng, Y.; Zaharia, S. G.; Fok, M. H.

    2010-01-01

    Plasma and field interaction is one important aspect of inner magnetospheric physics. The magnetic field controls particle motion through gradient, curvature drifts and E cross B drift. In this presentation, we show how the global magnetic field affects dynamics of the ring current through simulations of two moderate geomagnetic storms (20 November 2007 and 8-9 March 2008). Preliminary results of coupling the Comprehensive Ring Current Model (CRCM) with a three-dimensional plasma force balance code (to achieve self-consistency in both E and B fields) indicate that inclusion of self-consistency in B tends to mitigate the intensification of the ring current as other similar coupling efforts have shown. In our approach, self-consistency in the electric field is already an existing capability of the CRCM. The magnetic self-consistency is achieved by computing the three-dimensional magnetic field in force balance with anisotropic ring current ion distributions. We discuss the coupling methodology and its further improvement. In addition, comparative studies by using various magnetic field models will be shown. Simulation results will be put into a global context by analyzing the morphology of the ring current, its anisotropy and characteristics ofthe interconnected region 2 field-aligned currents.

  17. [Dynamics of ecological landscape pattern and its affecting factors in desert-oasis in Fukang, Xinjiang].

    PubMed

    Liu, Xinchun; Zhang, Yuandong; Ren, Guangyao; Pan, Xiaoling; He, Qing

    2004-07-01

    The spatial pattern of ecological landscape during land utilization in Fukang is heavily influenced by natural difference and the scale of water and land resource development. Analyses on the spatial pattern based on different zones and indexes showed that from 1987 to 1998, the change of the spatial pattern of ecological landscape during land utilization in Fukang was mainly the increase of plantation area in pluvial fan and the decrease in alluvial plain. The case was on the contrary about badlands. The acreage of woodland decreased in lower mountains, uplands and alluvial plain, but no variety in alluvial plain. The acreage of grassland increased in lower mountains and uplands, while decreased in other fields. The acreage of town increased in each sample field, while that of water area remained uncharged. The landscape diversity and evenness was descending, the dominance was ascending in lower mountains and in pluvial fan, while it was reverse in alluvial plain. Accessorial fragmentation showed the increasing influence of human beings. The change of the spatial pattern of ecological landscape in Fukang focused on the acreage alteration of plantation and badlands in pluvial fan and alluvial plain. The key factor was the dynamic variation of water-salt in water and soil resource utilization. Terrain and land utilization were the key factors affecting water table, and the continuous changes of the water table worked on the spatial distribution of soil water-salt. PMID:15506098

  18. A dynamic evolution model of human opinion as affected by advertising

    NASA Astrophysics Data System (ADS)

    Luo, Gui-Xun; Liu, Yun; Zeng, Qing-An; Diao, Su-Meng; Xiong, Fei

    2014-11-01

    We propose a new model to investigate the dynamics of human opinion as affected by advertising, based on the main idea of the CODA model and taking into account two practical factors: one is that the marginal influence of an additional friend will decrease with an increasing number of friends; the other is the decline of memory over time. Simulations show several significant conclusions for both advertising agencies and the general public. A small difference of advertising’s influence on individuals or advertising coverage will result in significantly different advertising effectiveness within a certain interval of value. Compared to the value of advertising’s influence on individuals, the advertising coverage plays a more important role due to the exponential decay of memory. Meanwhile, some of the obtained results are in accordance with people’s daily cognition about advertising. The real key factor in determining the success of advertising is the intensity of exchanging opinions, and people’s external actions always follow their internal opinions. Negative opinions also play an important role.

  19. Seasonal time bombs: dominant temperate viruses affect Southern Ocean microbial dynamics

    PubMed Central

    Brum, Jennifer R; Hurwitz, Bonnie L; Schofield, Oscar; Ducklow, Hugh W; Sullivan, Matthew B

    2016-01-01

    Rapid warming in the highly productive western Antarctic Peninsula (WAP) region of the Southern Ocean has affected multiple trophic levels, yet viral influences on microbial processes and ecosystem function remain understudied in the Southern Ocean. Here we use cultivation-independent quantitative ecological and metagenomic assays, combined with new comparative bioinformatic techniques, to investigate double-stranded DNA viruses during the WAP spring–summer transition. This study demonstrates that (i) temperate viruses dominate this region, switching from lysogeny to lytic replication as bacterial production increases, and (ii) Southern Ocean viral assemblages are genetically distinct from lower-latitude assemblages, primarily driven by this temperate viral dominance. This new information suggests fundamentally different virus–host interactions in polar environments, where intense seasonal changes in bacterial production select for temperate viruses because of increased fitness imparted by the ability to switch replication strategies in response to resource availability. Further, temperate viral dominance may provide mechanisms (for example, bacterial mortality resulting from prophage induction) that help explain observed temporal delays between, and lower ratios of, bacterial and primary production in polar versus lower-latitude marine ecosystems. Together these results suggest that temperate virus–host interactions are critical to predicting changes in microbial dynamics brought on by warming in polar marine systems. PMID:26296067

  20. Inclusion of chloromethane guests affects conformation and internal dynamics of cryptophane-D host.

    PubMed

    Takacs, Zoltan; Brotin, Thierry; Dutasta, Jean-Pierre; Lang, Jan; Todde, Guido; Kowalewski, Jozef

    2012-07-12

    Cryptophane-D is composed of two nonequivalent cyclotribenzylene caps bound together by three OCH2CH2O bridges in a syn arrangement. Host-guest complexes with chloroform and dichloromethane were investigated in solution by NMR spectroscopy. Variable temperature NMR (1)H and (13)C spectra showed effects of chemical exchange between the free and bound guest and of conformational exchange for the host, strongly and specifically affected by guest binding. We found in particular that the carbon-13 chemical shifts for the linkers connecting the two cyclotribenzylene units are very informative. The NMR results were supported by DFT calculations. The guest exchange was also studied quantitatively, either by EXSY measurements (for chloroform as guest) or by line-shape analysis (for dichloromethane as guest). In the case of chloroform guest, we also investigated cross-relaxation between the guest and host protons, as well as carbon-13 longitudinal relaxation and heteronuclear NOE at three different fields. The results were interpreted in terms of orientation and dynamics of the guest inside the host cavity. Putting together various types of evidence resulted in remarkably detailed insight into the process of molecular recognition of the two guests by cryptophane-D host.

  1. Infection dynamics of Cichlidogyrus tilapiae and C. sclerosus (Monogenea, Ancyrocephalinae) in Nile tilapia (Oreochromis niloticus L.) from Uganda.

    PubMed

    Akoll, P; Fioravanti, M L; Konecny, R; Schiemer, F

    2012-09-01

    The infection dynamics of the gill monogeneans Cichlidogyrus tilapiae and C. sclerosus on Oreochromis niloticus with respect to habitat type (reservoir, stream, ponds and cages), host sex, size and seasons was determined between January and November 2008. During the study period, 45.2% of the 650 fish examined were infected with Cichlidogyrus spp. The infected hosts harboured an average of 8.6 ± 3.4 parasites/fish. Across habitat types, the proportion of infected fish was not statistically different. In contrast, the number of parasites recorded on infected fish from different habitat types differed significantly. The highest parasite number was recorded in reservoir-dwelling fish and lowest in stream-dwelling hosts. Concerning sex, more female O. niloticus were infected and harboured a high number of parasites than male and sexually undifferentiated fish. A weak negative relationship was found between rainfall and monthly parasite infections. However, a higher number of parasites and proportion of infected hosts were found during dry than in wet seasons, except in ponds. Results of this study show that differential exposure due to changes in fish behaviour associated with habitat modification and sex may account for the infection difference across the sampled sites. Meanwhile, rainfall and the associated hydrological events are important factors regulating monogenean infections in tropical aquatic environments. The continuous presence of Cichlidogyrus spp. in fish provides evidence of possible parasite outbreaks, indicating the application of biosecurity measures as crucial for the success of intensive fish farming. PMID:21791155

  2. Analysis of Endothelial Adherence of Bartonella henselae and Acinetobacter baumannii Using a Dynamic Human Ex Vivo Infection Model

    PubMed Central

    Weidensdorfer, Marko; Chae, Ju Ik; Makobe, Celestine; Stahl, Julia; Averhoff, Beate; Müller, Volker; Schürmann, Christoph; Brandes, Ralf P.; Wilharm, Gottfried; Ballhorn, Wibke; Christ, Sara; Linke, Dirk; Fischer, Doris; Göttig, Stephan

    2015-01-01

    Bacterial adherence determines the virulence of many human-pathogenic bacteria. Experimental approaches elucidating this early infection event in greater detail have been performed using mainly methods of cellular microbiology. However, in vitro infections of cell monolayers reflect the in vivo situation only partially, and animal infection models are not available for many human-pathogenic bacteria. Therefore, ex vivo infection of human organs might represent an attractive method to overcome these limitations. We infected whole human umbilical cords ex vivo with Bartonella henselae or Acinetobacter baumannii under dynamic flow conditions mimicking the in vivo infection situation of human endothelium. For this purpose, methods for quantifying endothelium-adherent wild-type and trimeric autotransporter adhesin (TAA)-deficient bacteria were set up. Data revealed that (i) A. baumannii binds in a TAA-dependent manner to endothelial cells, (ii) this organ infection model led to highly reproducible adherence rates, and furthermore, (iii) this model allowed to dissect the biological function of TAAs in the natural course of human infections. These findings indicate that infection models using ex vivo human tissue samples (“organ microbiology”) might be a valuable tool in analyzing bacterial pathogenicity with the capacity to replace animal infection models at least partially. PMID:26712205

  3. Lymph node colonization dynamics after oral Salmonella Typhimurium infection in mice.

    PubMed

    Kaiser, Patrick; Slack, Emma; Grant, Andrew J; Hardt, Wolf-Dietrich; Regoes, Roland R

    2013-09-01

    An understanding of how pathogens colonize their hosts is crucial for the rational design of vaccines or therapy. While the molecular factors facilitating the invasion and systemic infection by pathogens are a central focus of research in microbiology, the population biological aspects of colonization are still poorly understood. Here, we investigated the early colonization dynamics of Salmonella enterica subspecies 1 serovar Typhimurium (S. Tm) in the streptomycin mouse model for diarrhea. We focused on the first step on the way to systemic infection -- the colonization of the cecal lymph node (cLN) from the gut -- and studied roles of inflammation, dendritic cells and innate immune effectors in the colonization process. To this end, we inoculated mice with mixtures of seven wild type isogenic tagged strains (WITS) of S. Tm. The experimental data were analyzed with a newly developed mathematical model describing the stochastic immigration, replication and clearance of bacteria in the cLN. We estimated that in the beginning of infection only 300 bacterial cells arrive in the cLN per day. We further found that inflammation decreases the net replication rate in the cLN by 23%. In ccr7(-/-) mice, in which dendritic cell movement is impaired, the bacterial migration rate was reduced 10-fold. In contrast, cybb(-/-) mice that cannot generate toxic reactive oxygen species displayed a 4-fold higher migration rate from gut to cLN than wild type mice. Thus, combining infections with mixed inocula of barcoded strains and mathematical analysis represents a powerful method for disentangling immigration into the cLN from replication in this compartment. The estimated parameters provide an important baseline to assess and predict the efficacy of interventions.

  4. [Dynamics of CD4⁺ T cell subsets and their roles in schistosome infections: a review].

    PubMed

    Fan, Xiao-lin; Gao, Qi; Yang, Jun-qi

    2015-12-01

    Schistosomiasis is a chronic helminthic disease that affects about two hundred millions of people in the world. The pathogenesis of schistosome infection is primarily due to hepatic and intestinal granuloma formation around deposited eggs and subsequent fibrosis. It is known that CD4⁺ T cell subsets play critical roles in the host immunity and immunopathogenesis to schistosome infections, in which T helper 1 (Th1) and Th2 cells are major effector T cell subsets, whereas T regulatory (Treg) cells exert immunosuppressive roles in general. The recently discovered Th17 cells are also actively involved in the immune responses to the infection. During the infection, these T cell subsets cross-talk and exhibit different kinetics and roles in the control and regulation of infection progress and fibrosis. This review summarizes current findings of Th1, Th2, Th17 and Treg cells and their effector cytokines in schistosome infection. PMID:27097497

  5. Dynamics of virus shedding and antibody responses in influenza A virus-infected feral swine.

    PubMed

    Sun, Hailiang; Cunningham, Fred L; Harris, Jillian; Xu, Yifei; Long, Li-Ping; Hanson-Dorr, Katie; Baroch, John A; Fioranelli, Paul; Lutman, Mark W; Li, Tao; Pedersen, Kerri; Schmit, Brandon S; Cooley, Jim; Lin, Xiaoxu; Jarman, Richard G; DeLiberto, Thomas J; Wan, Xiu-Feng

    2015-09-01

    Given their free-ranging habits, feral swine could serve as reservoirs or spatially dynamic 'mixing vessels' for influenza A virus (IAV). To better understand virus shedding patterns and antibody response dynamics in the context of IAV surveillance amongst feral swine, we used IAV of feral swine origin to perform infection experiments. The virus was highly infectious and transmissible in feral swine, and virus shedding patterns and antibody response dynamics were similar to those in domestic swine. In the virus-inoculated and sentinel groups, virus shedding lasted ≤ 6 and ≤ 9 days, respectively. Antibody titres in inoculated swine peaked at 1 : 840 on day 11 post-inoculation (p.i.), remained there until 21 days p.i. and dropped to < 1 : 220 at 42 days p.i. Genomic sequencing identified changes in wildtype (WT) viruses and isolates from sentinel swine, most notably an amino acid divergence in nucleoprotein position 473. Using data from cell culture as a benchmark, sensitivity and specificity of a matrix gene-based quantitative reverse transcription-PCR method using nasal swab samples for detection of IAV in feral swine were 78.9 and 78.1 %, respectively. Using data from haemagglutination inhibition assays as a benchmark, sensitivity and specificity of an ELISA for detection of IAV-specific antibody were 95.4 and 95.0 %, respectively. Serological surveillance from 2009 to 2014 showed that ∼7.58 % of feral swine in the USA were positive for IAV. Our findings confirm the susceptibility of IAV infection and the high transmission ability of IAV amongst feral swine, and also suggest the need for continued surveillance of IAVs in feral swine populations. PMID:26297148

  6. Dynamics of virus shedding and antibody responses in influenza A virus-infected feral swine

    PubMed Central

    Sun, Hailiang; Cunningham, Fred L.; Harris, Jillian; Xu, Yifei; Long, Li-Ping; Hanson-Dorr, Katie; Baroch, John A.; Fioranelli, Paul; Lutman, Mark W.; Li, Tao; Pedersen, Kerri; Schmit, Brandon S.; Cooley, Jim; Lin, Xiaoxu; Jarman, Richard G.; DeLiberto, Thomas J.

    2015-01-01

    Given their free-ranging habits, feral swine could serve as reservoirs or spatially dynamic ‘mixing vessels’ for influenza A virus (IAV). To better understand virus shedding patterns and antibody response dynamics in the context of IAV surveillance amongst feral swine, we used IAV of feral swine origin to perform infection experiments. The virus was highly infectious and transmissible in feral swine, and virus shedding patterns and antibody response dynamics were similar to those in domestic swine. In the virus-inoculated and sentinel groups, virus shedding lasted ≤ 6 and ≤ 9 days, respectively. Antibody titres in inoculated swine peaked at 1 : 840 on day 11 post-inoculation (p.i.), remained there until 21 days p.i. and dropped to < 1 : 220 at 42 days p.i. Genomic sequencing identified changes in wildtype (WT) viruses and isolates from sentinel swine, most notably an amino acid divergence in nucleoprotein position 473. Using data from cell culture as a benchmark, sensitivity and specificity of a matrix gene-based quantitative reverse transcription-PCR method using nasal swab samples for detection of IAV in feral swine were 78.9 and 78.1 %, respectively. Using data from haemagglutination inhibition assays as a benchmark, sensitivity and specificity of an ELISA for detection of IAV-specific antibody were 95.4 and 95.0 %, respectively. Serological surveillance from 2009 to 2014 showed that ∼7.58 % of feral swine in the USA were positive for IAV. Our findings confirm the susceptibility of IAV infection and the high transmission ability of IAV amongst feral swine, and also suggest the need for continued surveillance of IAVs in feral swine populations. PMID:26297148

  7. Temporal and spatial dynamics of trypanosomes infecting the brush-tailed bettong (Bettongia penicillata): a cautionary note of disease-induced population decline

    PubMed Central

    2014-01-01

    Background The brush-tailed bettong or woylie (Bettongia penicillata) is on the brink of extinction. Its numbers have declined by 90% since 1999, with their current distribution occupying less than 1% of their former Australian range. Woylies are known to be infected with three different trypanosomes (Trypanosoma vegrandis, Trypanosoma copemani and Trypanosoma sp. H25) and two different strains of T. copemani that vary in virulence. However, the role that these haemoparasites have played during the recent decline of their host is unclear and is part of ongoing investigation. Methods Woylies were sampled from five locations in southern Western Australia, including two neighbouring indigenous populations, two enclosed (fenced) populations and a captive colony. PCR was used to individually identify the three different trypanosomes from blood and tissues of the host, and to investigate the temporal and spatial dynamics of trypanosome infections. Results The spatial pattern of trypanosome infection varied among the five study sites, with a greater proportion of woylies from the Perup indigenous population being infected with T. copemani than from the neighbouring Kingston indigenous population. For an established infection, T. copemani detection was temporally inconsistent. The more virulent strain of T. copemani appeared to regress at a faster rate than the less virulent strain, with the infection possibly transitioning from the acute to chronic phase. Interspecific competition may also exist between T. copemani and T. vegrandis, where an existing T. vegrandis infection may moderate the sequential establishment of the more virulent T. copemani. Conclusion In this study, we provide a possible temporal connection implicating T. copemani as the disease agent linked with the recent decline of the Kingston indigenous woylie population within the Upper Warren region of Western Australia. The chronic association of trypanosomes with the internal organs of its host may be

  8. Whipworm infection

    MedlinePlus

    ... of the large intestine with a type of roundworm. ... Whipworm infection is caused by the roundworm Trichuris trichiura. It is a common infection that mainly affects children. Children may become infected if they swallow soil contaminated with whipworm ...

  9. Eye Infections

    MedlinePlus

    Your eyes can get infections from bacteria, fungi, or viruses. Eye infections can occur in different parts of the eye and can affect just one eye or both. Two common eye infections are Conjunctivitis - also known as pinkeye. Conjunctivitis is ...

  10. A bacteriophage tubulin harnesses dynamic instability to center DNA in infected cells.

    PubMed

    Erb, Marcella L; Kraemer, James A; Coker, Joanna K C; Chaikeeratisak, Vorrapon; Nonejuie, Poochit; Agard, David A; Pogliano, Joe

    2014-01-01

    Dynamic instability, polarity, and spatiotemporal organization are hallmarks of the microtubule cytoskeleton that allow formation of complex structures such as the eukaryotic spindle. No similar structure has been identified in prokaryotes. The bacteriophage-encoded tubulin PhuZ is required to position DNA at mid-cell, without which infectivity is compromised. Here, we show that PhuZ filaments, like microtubules, stochastically switch from growing in a distinctly polar manner to catastrophic depolymerization (dynamic instability) both in vitro and in vivo. One end of each PhuZ filament is stably anchored near the cell pole to form a spindle-like array that orients the growing ends toward the phage nucleoid so as to position it near mid-cell. Our results demonstrate how a bacteriophage can harness the properties of a tubulin-like cytoskeleton for efficient propagation. This represents the first identification of a prokaryotic tubulin with the dynamic instability of microtubules and the ability to form a simplified bipolar spindle.

  11. Nitrogen storage dynamics are affected by masting events in Fagus crenata.

    PubMed

    Han, Qingmin; Kabeya, Daisuke; Iio, Atsuhiro; Inagaki, Yoshiyuki; Kakubari, Yoshitaka

    2014-03-01

    It is generally assumed that the production of a large crop of seeds depletes stores of resources and that these take more than 1 year to replenish; this is accepted, theoretically, as the proximate mechanism of mast seeding (resource budget model). However, direct evidence of resource depletion in masting trees is very rare. Here, we trace seasonal and inter-annual variations in nitrogen (N) concentration and estimate the N storage pool of individuals after full masting of Fagus crenata in two stands. In 2005, a full masting year, the amount of N in fruit litter represented half of the N present in mature leaves in an old stand (age 190-260 years), and was about equivalent to the amount of N in mature leaves in a younger stand (age 83-84 years). Due to this additional burden, both tissue N concentration and individual N storage decreased in 2006; this was followed by significant replenishment in 2007, although a substantial N store remained even after full masting. These results indicate that internal storage may be important and that N may be the limiting factor for fruiting. In the 4 years following full masting, the old stand experienced two moderate masting events separated by 2 years, whilst trees in the younger stand did not fruit. This different fruiting behavior may be related to different "costs of reproduction" in the full masting year 2005, thus providing more evidence that N may limit fruiting. Compared to the non-fruiting stand, individuals in the fruiting stand exhibited an additional increase in N concentrations in roots early in the 2007 growing season, suggesting additional N uptake from the soil to supply resource demand. The enhanced uptake may alleviate the N storage depletion observed in the full masting year. This study suggests that masting affects N cycle dynamics in mature Fagus crenata and N may be one factor limiting fruiting. PMID:24221082

  12. Rotational diffusion affects the dynamical self-assembly pathways of patchy particles.

    PubMed

    Newton, Arthur C; Groenewold, Jan; Kegel, Willem K; Bolhuis, Peter G

    2015-12-15

    Predicting the self-assembly kinetics of particles with anisotropic interactions, such as colloidal patchy particles or proteins with multiple binding sites, is important for the design of novel high-tech materials, as well as for understanding biological systems, e.g., viruses or regulatory networks. Often stochastic in nature, such self-assembly processes are fundamentally governed by rotational and translational diffusion. Whereas the rotational diffusion constant of particles is usually considered to be coupled to the translational diffusion via the Stokes-Einstein relation, in the past decade it has become clear that they can be independently altered by molecular crowding agents or via external fields. Because virus capsids naturally assemble in crowded environments such as the cell cytoplasm but also in aqueous solution in vitro, it is important to investigate how varying the rotational diffusion with respect to transitional diffusion alters the kinetic pathways of self-assembly. Kinetic trapping in malformed or intermediate structures often impedes a direct simulation approach of a kinetic network by dramatically slowing down the relaxation to the designed ground state. However, using recently developed path-sampling techniques, we can sample and analyze the entire self-assembly kinetic network of simple patchy particle systems. For assembly of a designed cluster of patchy particles we find that changing the rotational diffusion does not change the equilibrium constants, but significantly affects the dynamical pathways, and enhances (suppresses) the overall relaxation process and the yield of the target structure, by avoiding (encountering) frustrated states. Besides insight, this finding provides a design principle for improved control of nanoparticle self-assembly.

  13. How the type of input function affects the dynamic response of conducting polymer actuators

    NASA Astrophysics Data System (ADS)

    Xiang, Xingcan; Alici, Gursel; Mutlu, Rahim; Li, Weihua

    2014-10-01

    There has been a growing interest in smart actuators typified by conducting polymer actuators, especially in their (i) fabrication, modeling and control with minimum external data and (ii) applications in bio-inspired devices, robotics and mechatronics. Their control is a challenging research problem due to the complex and nonlinear properties of these actuators, which cannot be predicted accurately. Based on an input-shaping technique, we propose a new method to improve the conducting polymer actuators’ command-following ability, while minimizing their electric power consumption. We applied four input functions with smooth characteristics to a trilayer conducting polymer actuator to experimentally evaluate its command-following ability under an open-loop control strategy and a simulated feedback control strategy, and, more importantly, to quantify how the type of input function affects the dynamic response of this class of actuators. We have found that the four smooth inputs consume less electrical power than sharp inputs such as a step input with discontinuous higher-order derivatives. We also obtained an improved transient response performance from the smooth inputs, especially under the simulated feedback control strategy, which we have proposed previously [X Xiang, R Mutlu, G Alici, and W Li, 2014 “Control of conducting polymer actuators without physical feedback: simulated feedback control approach with particle swarm optimization’, Journal of Smart Materials and Structure, 23]. The idea of using a smooth input command, which results in lower power consumption and better control performance, can be extended to other smart actuators. Consuming less electrical energy or power will have a direct effect on enhancing the operational life of these actuators.

  14. Secretagogin affects insulin secretion in pancreatic β-cells by regulating actin dynamics and focal adhesion

    PubMed Central

    Yang, Seo-Yun; Lee, Jae-Jin; Lee, Jin-Hee; Lee, Kyungeun; Oh, Seung Hoon; Lim, Yu-Mi; Lee, Myung-Shik; Lee, Kong-Joo

    2016-01-01

    Secretagogin (SCGN), a Ca2+-binding protein having six EF-hands, is selectively expressed in pancreatic β-cells and neuroendocrine cells. Previous studies suggested that SCGN enhances insulin secretion by functioning as a Ca2+-sensor protein, but the underlying mechanism has not been elucidated. The present study explored the mechanism by which SCGN enhances glucose-induced insulin secretion in NIT-1 insulinoma cells. To determine whether SCGN influences the first or second phase of insulin secretion, we examined how SCGN affects the kinetics of insulin secretion in NIT-1 cells. We found that silencing SCGN suppressed the second phase of insulin secretion induced by glucose and H2O2, but not the first phase induced by KCl stimulation. Recruitment of insulin granules in the second phase of insulin secretion was significantly impaired by knocking down SCGN in NIT-1 cells. In addition, we found that SCGN interacts with the actin cytoskeleton in the plasma membrane and regulates actin remodelling in a glucose-dependent manner. Since actin dynamics are known to regulate focal adhesion, a critical step in the second phase of insulin secretion, we examined the effect of silencing SCGN on focal adhesion molecules, including FAK (focal adhesion kinase) and paxillin, and the cell survival molecules ERK1/2 (extracellular-signal-regulated kinase 1/2) and Akt. We found that glucose- and H2O2-induced activation of FAK, paxillin, ERK1/2 and Akt was significantly blocked by silencing SCGN. We conclude that SCGN controls glucose-stimulated insulin secretion and thus may be useful in the therapy of Type 2 diabetes. PMID:27095850

  15. Plasma Membrane Factor XIIIA Transglutaminase Activity Regulates Osteoblast Matrix Secretion and Deposition by Affecting Microtubule Dynamics

    PubMed Central

    Al-Jallad, Hadil F.; Myneni, Vamsee D.; Piercy-Kotb, Sarah A.; Chabot, Nicolas; Mulani, Amina; Keillor, Jeffrey W.; Kaartinen, Mari T.

    2011-01-01

    Transglutaminase activity, arising potentially from transglutaminase 2 (TG2) and Factor XIIIA (FXIIIA), has been linked to osteoblast differentiation where it is required for type I collagen and fibronectin matrix deposition. In this study we have used an irreversible TG-inhibitor to ‘block –and-track’ enzyme(s) targeted during osteoblast differentiation. We show that the irreversible TG-inhibitor is highly potent in inhibiting osteoblast differentiation and mineralization and reduces secretion of both fibronectin and type I collagen and their release from the cell surface. Tracking of the dansyl probe by Western blotting and immunofluorescence microscopy demonstrated that the inhibitor targets plasma membrane-associated FXIIIA. TG2 appears not to contribute to crosslinking activity on the osteoblast surface. Inhibition of FXIIIA with NC9 resulted in defective secretory vesicle delivery to the plasma membrane which was attributable to a disorganized microtubule network and decreased microtubule association with the plasma membrane. NC9 inhibition of FXIIIA resulted in destabilization of microtubules as assessed by cellular Glu-tubulin levels. Furthermore, NC9 blocked modification of Glu-tubulin into 150 kDa high-molecular weight Glu-tubulin form which was specifically localized to the plasma membrane. FXIIIA enzyme and its crosslinking activity were colocalized with plasma membrane-associated tubulin, and thus, it appears that FXIIIA crosslinking activity is directed towards stabilizing the interaction of microtubules with the plasma membrane. Our work provides the first mechanistic cues as to how transglutaminase activity could affect protein secretion and matrix deposition in osteoblasts and suggests a novel function for plasma membrane FXIIIA in microtubule dynamics. PMID:21283799

  16. Rotational diffusion affects the dynamical self-assembly pathways of patchy particles

    PubMed Central

    Newton, Arthur C.; Groenewold, Jan; Kegel, Willem K.; Bolhuis, Peter G.

    2015-01-01

    Predicting the self-assembly kinetics of particles with anisotropic interactions, such as colloidal patchy particles or proteins with multiple binding sites, is important for the design of novel high-tech materials, as well as for understanding biological systems, e.g., viruses or regulatory networks. Often stochastic in nature, such self-assembly processes are fundamentally governed by rotational and translational diffusion. Whereas the rotational diffusion constant of particles is usually considered to be coupled to the translational diffusion via the Stokes–Einstein relation, in the past decade it has become clear that they can be independently altered by molecular crowding agents or via external fields. Because virus capsids naturally assemble in crowded environments such as the cell cytoplasm but also in aqueous solution in vitro, it is important to investigate how varying the rotational diffusion with respect to transitional diffusion alters the kinetic pathways of self-assembly. Kinetic trapping in malformed or intermediate structures often impedes a direct simulation approach of a kinetic network by dramatically slowing down the relaxation to the designed ground state. However, using recently developed path-sampling techniques, we can sample and analyze the entire self-assembly kinetic network of simple patchy particle systems. For assembly of a designed cluster of patchy particles we find that changing the rotational diffusion does not change the equilibrium constants, but significantly affects the dynamical pathways, and enhances (suppresses) the overall relaxation process and the yield of the target structure, by avoiding (encountering) frustrated states. Besides insight, this finding provides a design principle for improved control of nanoparticle self-assembly. PMID:26621742

  17. Secretagogin affects insulin secretion in pancreatic β-cells by regulating actin dynamics and focal adhesion.

    PubMed

    Yang, Seo-Yun; Lee, Jae-Jin; Lee, Jin-Hee; Lee, Kyungeun; Oh, Seung Hoon; Lim, Yu-Mi; Lee, Myung-Shik; Lee, Kong-Joo

    2016-06-15

    Secretagogin (SCGN), a Ca(2+)-binding protein having six EF-hands, is selectively expressed in pancreatic β-cells and neuroendocrine cells. Previous studies suggested that SCGN enhances insulin secretion by functioning as a Ca(2+)-sensor protein, but the underlying mechanism has not been elucidated. The present study explored the mechanism by which SCGN enhances glucose-induced insulin secretion in NIT-1 insulinoma cells. To determine whether SCGN influences the first or second phase of insulin secretion, we examined how SCGN affects the kinetics of insulin secretion in NIT-1 cells. We found that silencing SCGN suppressed the second phase of insulin secretion induced by glucose and H2O2, but not the first phase induced by KCl stimulation. Recruitment of insulin granules in the second phase of insulin secretion was significantly impaired by knocking down SCGN in NIT-1 cells. In addition, we found that SCGN interacts with the actin cytoskeleton in the plasma membrane and regulates actin remodelling in a glucose-dependent manner. Since actin dynamics are known to regulate focal adhesion, a critical step in the second phase of insulin secretion, we examined the effect of silencing SCGN on focal adhesion molecules, including FAK (focal adhesion kinase) and paxillin, and the cell survival molecules ERK1/2 (extracellular-signal-regulated kinase 1/2) and Akt. We found that glucose- and H2O2-induced activation of FAK, paxillin, ERK1/2 and Akt was significantly blocked by silencing SCGN. We conclude that SCGN controls glucose-stimulated insulin secretion and thus may be useful in the therapy of Type 2 diabetes. PMID:27095850

  18. Interactions between surface roughness and airflow turbulence affecting drying dynamics of rough porous surfaces

    NASA Astrophysics Data System (ADS)

    Haghighi, Erfan; Kirchner, James; Or, Dani

    2016-04-01

    Evaporative drying of porous surfaces interacting with turbulent airflows is common in various industrial and natural applications. The intrinsic relief and roughness of natural porous surfaces are likely to influence the structure of interacting turbulent airflow boundary layers, and thus affect rates and patterns of heat and vapor fluxes from the surface. These links have been formalized in new mechanistic models that consider intermittent and localized turbulence-induced boundary layers, resulting in rich surface evaporation and energy exchange dynamics. The models were evaluated experimentally by systematically varying surface roughness elements in drying experiments of wavy and bluff-body covered sand surfaces in a wind tunnel. Thermal infrared signatures of localized evaporative fluxes as well as mean evaporative mass losses were recorded. The resulting patterns were in good agreement with model predictions for local and surface averaged turbulent exchange rates. Experimental and theoretical results suggest that evaporative water losses from wavy sand surfaces can be either enhanced or suppressed (relative to a flat surface), due to the complex interplay between the local boundary layer thickness and internal limitations on water flow to the evaporating surface. For sand surfaces covered by isolated cylindrical elements (bluff bodies), model predictions and measurements show persistent enhancement of evaporative fluxes from bluff-rough surfaces compared to a flat surface under similar conditions. This enhancement is attributed to the formation of vortices that thin the boundary layer over part of the interacting surface footprint. The implications of this study for interpreting and upscaling evapotranspiration rates from terrestrial surfaces will be discussed.

  19. Public Policy Affirmations Affecting the Planning and Implementation of Developmental Services for Children and Adults with HIV Infection.

    ERIC Educational Resources Information Center

    Crocker, Allen C., Comp.; And Others

    The increasing number of individuals infected with symptomatic human immunodeficiency virus (HIV) infection has created a need to examine public policy issues and to further efforts in planning, implementing, and evaluating services for individuals with HIV infection and their families. A working conference was convened, which identified several…

  20. Host response dynamics following lethal infection of rhesus macaques with Zaire ebolavirus.

    PubMed

    Ebihara, Hideki; Rockx, Barry; Marzi, Andrea; Feldmann, Friederike; Haddock, Elaine; Brining, Douglas; LaCasse, Rachel A; Gardner, Don; Feldmann, Heinz

    2011-11-01

    To gain further insight into the interdependent pathogenic processes in Ebola hemorrhagic fever (EHF), we have examined the dynamics of host responses in individual rhesus macaques infected with Zaire ebolavirus over the entire disease course. Examination of coagulation parameters revealed that decreased coagulation inhibitor activity triggered severe coagulopathy as indicated by prolonged coagulation times and decreased fibrinogen levels. This has been proposed as one of the significant mechanisms underlying disseminated intravascular coagulation in EHF patients. Furthermore, monitoring of expression levels for cytokines/chemokines suggested a mixed anti-inflammatory response syndrome (MARS), which indicates that a catastrophic uncontrolled immunological status contributes to the development of fatal hemorrhagic fever. These results highlight the pathological analogies between EHF and severe sepsis and not only contribute to our understanding of the pathogenic process, but will also help to establish novel postexposure treatment modalities.

  1. Dynamic Association between Negative Affect and Alcohol Lapses following Alcohol Treatment

    ERIC Educational Resources Information Center

    Witkiewitz, Katie; Villarroel, Nadia Aracelliz

    2009-01-01

    Clinical research has found a strong association between negative affect and returning to alcohol use after a period of abstinence. Yet little is known about the probability of a lapse given a particular level of negative affect or whether there is a reciprocal relationship between negative affect and alcohol use across time. The goal of the…

  2. A Unified Framework for the Infection Dynamics of Zoonotic Spillover and Spread.

    PubMed

    Lo Iacono, Giovanni; Cunningham, Andrew A; Fichet-Calvet, Elisabeth; Garry, Robert F; Grant, Donald S; Leach, Melissa; Moses, Lina M; Nichols, Gordon; Schieffelin, John S; Shaffer, Jeffrey G; Webb, Colleen T; Wood, James L N

    2016-09-01

    A considerable amount of disease is transmitted from animals to humans and many of these zoonoses are neglected tropical diseases. As outbreaks of SARS, avian influenza and Ebola have demonstrated, however, zoonotic diseases are serious threats to global public health and are not just problems confined to remote regions. There are two fundamental, and poorly studied, stages of zoonotic disease emergence: 'spillover', i.e. transmission of pathogens from animals to humans, and 'stuttering transmission', i.e. when limited human-to-human infections occur, leading to self-limiting chains of transmission. We developed a transparent, theoretical framework, based on a generalization of Poisson processes with memory of past human infections, that unifies these stages. Once we have quantified pathogen dynamics in the reservoir, with some knowledge of the mechanism of contact, the approach provides a tool to estimate the likelihood of spillover events. Comparisons with independent agent-based models demonstrates the ability of the framework to correctly estimate the relative contributions of human-to-human vs animal transmission. As an illustrative example, we applied our model to Lassa fever, a rodent-borne, viral haemorrhagic disease common in West Africa, for which data on human outbreaks were available. The approach developed here is general and applicable to a range of zoonoses. This kind of methodology is of crucial importance for the scientific, medical and public health communities working at the interface between animal and human diseases to assess the risk associated with the disease and to plan intervention and appropriate control measures. The Lassa case study revealed important knowledge gaps, and opportunities, arising from limited knowledge of the temporal patterns in reporting, abundance of and infection prevalence in, the host reservoir.

  3. A Unified Framework for the Infection Dynamics of Zoonotic Spillover and Spread

    PubMed Central

    Cunningham, Andrew A.; Fichet-Calvet, Elisabeth; Garry, Robert F.; Grant, Donald S.; Leach, Melissa; Moses, Lina M.; Nichols, Gordon; Schieffelin, John S.; Shaffer, Jeffrey G.; Webb, Colleen T.; Wood, James L. N.

    2016-01-01

    A considerable amount of disease is transmitted from animals to humans and many of these zoonoses are neglected tropical diseases. As outbreaks of SARS, avian influenza and Ebola have demonstrated, however, zoonotic diseases are serious threats to global public health and are not just problems confined to remote regions. There are two fundamental, and poorly studied, stages of zoonotic disease emergence: ‘spillover’, i.e. transmission of pathogens from animals to humans, and ‘stuttering transmission’, i.e. when limited human-to-human infections occur, leading to self-limiting chains of transmission. We developed a transparent, theoretical framework, based on a generalization of Poisson processes with memory of past human infections, that unifies these stages. Once we have quantified pathogen dynamics in the reservoir, with some knowledge of the mechanism of contact, the approach provides a tool to estimate the likelihood of spillover events. Comparisons with independent agent-based models demonstrates the ability of the framework to correctly estimate the relative contributions of human-to-human vs animal transmission. As an illustrative example, we applied our model to Lassa fever, a rodent-borne, viral haemorrhagic disease common in West Africa, for which data on human outbreaks were available. The approach developed here is general and applicable to a range of zoonoses. This kind of methodology is of crucial importance for the scientific, medical and public health communities working at the interface between animal and human diseases to assess the risk associated with the disease and to plan intervention and appropriate control measures. The Lassa case study revealed important knowledge gaps, and opportunities, arising from limited knowledge of the temporal patterns in reporting, abundance of and infection prevalence in, the host reservoir. PMID:27588425

  4. A Unified Framework for the Infection Dynamics of Zoonotic Spillover and Spread.

    PubMed

    Lo Iacono, Giovanni; Cunningham, Andrew A; Fichet-Calvet, Elisabeth; Garry, Robert F; Grant, Donald S; Leach, Melissa; Moses, Lina M; Nichols, Gordon; Schieffelin, John S; Shaffer, Jeffrey G; Webb, Colleen T; Wood, James L N

    2016-09-01

    A considerable amount of disease is transmitted from animals to humans and many of these zoonoses are neglected tropical diseases. As outbreaks of SARS, avian influenza and Ebola have demonstrated, however, zoonotic diseases are serious threats to global public health and are not just problems confined to remote regions. There are two fundamental, and poorly studied, stages of zoonotic disease emergence: 'spillover', i.e. transmission of pathogens from animals to humans, and 'stuttering transmission', i.e. when limited human-to-human infections occur, leading to self-limiting chains of transmission. We developed a transparent, theoretical framework, based on a generalization of Poisson processes with memory of past human infections, that unifies these stages. Once we have quantified pathogen dynamics in the reservoir, with some knowledge of the mechanism of contact, the approach provides a tool to estimate the likelihood of spillover events. Comparisons with independent agent-based models demonstrates the ability of the framework to correctly estimate the relative contributions of human-to-human vs animal transmission. As an illustrative example, we applied our model to Lassa fever, a rodent-borne, viral haemorrhagic disease common in West Africa, for which data on human outbreaks were available. The approach developed here is general and applicable to a range of zoonoses. This kind of methodology is of crucial importance for the scientific, medical and public health communities working at the interface between animal and human diseases to assess the risk associated with the disease and to plan intervention and appropriate control measures. The Lassa case study revealed important knowledge gaps, and opportunities, arising from limited knowledge of the temporal patterns in reporting, abundance of and infection prevalence in, the host reservoir. PMID:27588425

  5. Genetics and infection dynamics of Paratrichosoma sp in farmed saltwater crocodiles (Crocodylus porosus).

    PubMed

    Lott, M J; Hose, G C; Isberg, S R; Power, M L

    2015-02-01

    Paratrichosoma-associated helminthiasis has been identified in saltwater crocodiles under intensive farming conditions. The development of sustainable integrated management practices is dependent on a detailed understanding of Paratrichosoma population genetics and infection dynamics. This study investigated the genetic relationships of Paratrichosoma sp in a population of commercially farmed saltwater crocodiles, Crocodylus porosus, in northern Australia. 18S ribosomal RNA gene sequence data were obtained from Paratrichosoma sp eggs present in the epidermis of infected animals. A high level of genetic diversity was distributed within the Paratrichosoma sp population (241 variable positions in the 1094 bp alignment), indicating an accelerated rate of nucleotide base-pair substitutions in this genus of nematodes. Several possible environmental correlates of the incidence and intensity of helminthiasis, including season, rainfall, and mean monthly temperature, were investigated by visual inspection of crocodile skins. Stepwise logistic regression revealed a significant negative linear relationship (P = 0.011, R (2) = 32.69 %) between mean monthly rainfall and the incidence of monthly Paratrichosoma-associated helminthiasis. Variation in the severity of Paratrichosoma-associated helminthiasis could not be explained by any of the independent environmental variables included within an ordinal regression analysis. The large genetic diversity in these nematodes indicates a high probability of anthelmintic resistant alleles occurring in the population. We discuss how the spread of these alleles may be mitigated by adopting targeted treatment protocols.

  6. Transcriptional dynamics of Phytophthora infestans during sequential stages of hemibiotrophic infection of tomato.

    PubMed

    Zuluaga, Andrea P; Vega-Arreguín, Julio C; Fei, Zhangjun; Ponnala, Lalit; Lee, Sang Jik; Matas, Antonio J; Patev, Sean; Fry, William E; Rose, Jocelyn K C

    2016-01-01

    Hemibiotrophic plant pathogens, such as the oomycete Phytophthora infestans, employ a biphasic infection strategy, initially behaving as biotrophs, where minimal symptoms are exhibited by the plant, and subsequently as necrotrophs, feeding on dead plant tissue. The regulation of this transition and the breadth of molecular mechanisms that modulate plant defences are not well understood, although effector proteins secreted by the pathogen are thought to play a key role. We examined the transcriptional dynamics of P. infestans in a compatible interaction with its host tomato (Solanum lycopersicum) at three infection stages: biotrophy; the transition from biotrophy to necrotrophy; and necrotrophy. The expression data suggest a tight temporal regulation of many pathways associated with the suppression of plant defence mechanisms and pathogenicity, including the induction of putative cytoplasmic and apoplastic effectors. Twelve of these were experimentally evaluated to determine their ability to suppress necrosis caused by the P. infestans necrosis-inducing protein PiNPP1.1 in Nicotiana benthamiana. Four effectors suppressed necrosis, suggesting that they might prolong the biotrophic phase. This study suggests that a complex regulation of effector expression modulates the outcome of the interaction.

  7. Genetics and infection dynamics of Paratrichosoma sp in farmed saltwater crocodiles (Crocodylus porosus).

    PubMed

    Lott, M J; Hose, G C; Isberg, S R; Power, M L

    2015-02-01

    Paratrichosoma-associated helminthiasis has been identified in saltwater crocodiles under intensive farming conditions. The development of sustainable integrated management practices is dependent on a detailed understanding of Paratrichosoma population genetics and infection dynamics. This study investigated the genetic relationships of Paratrichosoma sp in a population of commercially farmed saltwater crocodiles, Crocodylus porosus, in northern Australia. 18S ribosomal RNA gene sequence data were obtained from Paratrichosoma sp eggs present in the epidermis of infected animals. A high level of genetic diversity was distributed within the Paratrichosoma sp population (241 variable positions in the 1094 bp alignment), indicating an accelerated rate of nucleotide base-pair substitutions in this genus of nematodes. Several possible environmental correlates of the incidence and intensity of helminthiasis, including season, rainfall, and mean monthly temperature, were investigated by visual inspection of crocodile skins. Stepwise logistic regression revealed a significant negative linear relationship (P = 0.011, R (2) = 32.69 %) between mean monthly rainfall and the incidence of monthly Paratrichosoma-associated helminthiasis. Variation in the severity of Paratrichosoma-associated helminthiasis could not be explained by any of the independent environmental variables included within an ordinal regression analysis. The large genetic diversity in these nematodes indicates a high probability of anthelmintic resistant alleles occurring in the population. We discuss how the spread of these alleles may be mitigated by adopting targeted treatment protocols. PMID:25416333

  8. Exploratory study on the influence of climatological parameters on Mycoplasma hyopneumoniae infection dynamics

    NASA Astrophysics Data System (ADS)

    Segalés, Joaquim; Valero, Oliver; Espinal, Anna; López-Soria, Sergio; Nofrarías, Miquel; Calsamiglia, Maria; Sibila, Marina

    2012-11-01

    The objective of the present work was to elucidate the potential relationship between Mycoplasma hyopneumoniae infection and seroconversion dynamics and climatological conditions in four groups of pigs from the same farm born in different seasons of the year. Nasal swabs and blood samples were taken from 184 pigs at 1, 3, 6, 9, 12, 15, 18, 22 and 25 (slaughter age) weeks of age. Outside climatologic parameters, including temperature (°C), relative humidity (%), precipitation (l/m2) and wind speed (m/s) were recorded weekly from January 2003 to June 2004. Percentage of nPCR detection of M. hyopneumoniae in nasal swabs was associated significantly with the weekly precipitation rate [ P = 0.0018, OR = 1.31 (IC = 1.11-1.55)]; the higher the precipitation rate, the higher the probability of being M. hyopneumoniae nPCR-positive. On the other hand, the percentage of seropositive pigs had a significant association with mean weekly temperature rate [ P = 0.0012, OR = 0.89 [IC = 0.84-0.95]); the lower the temperature, the higher the probability of being M. hyopneumoniae seropositive. Animals born in autumn (when higher precipitations rates were recorded), entering finishing units in winter (when lower temperatures were recorded), and reaching slaughter in spring, had the highest probability of being infected by M. hyopneumoniae and the highest probability of being M. hyopneumoniae seropositive.

  9. The dynamics of avian influenza in Lesser Snow Geese: implications for annual and migratory infection patterns.

    PubMed

    Samuel, Michael D; Hall, Jeffrey S; Brown, Justin D; Goldberg, Diana R; Ip, Hon; Baranyuk, Vasily V

    2015-10-01

    Wild water birds are the natural reservoir for low-pathogenic avian influenza viruses (AIV). However, our ability to investigate the epizootiology of AIV in these migratory populations is challenging and, despite intensive worldwide surveillance, remains poorly understood. We conducted a cross-sectional, retrospective analysis in Pacific Flyway Lesser Snow Geese, Chen caerulescens, to investigate AIV serology and infection patterns. We collected nearly 3000 sera samples from Snow Geese at two breeding colonies in Russia and Canada during 1993-1996 and swab samples from >4000 birds at wintering and migration areas in the United States during 2006-2011. We found seroprevalence and annual seroconversion varied considerably among years. Seroconversion and infection rates also differed between Snow Goose breeding colonies and wintering areas, suggesting that AIV exposure in this gregarious waterfowl species is likely occurring during several phases (migration, wintering, and potentially breeding areas) of the annual cycle. We estimated AIV antibody persistence was longer (14 months) in female geese compared to males (6 months). This relatively long period of AIV antibody persistence suggests that subtype-specific serology may be an effective tool for detection of exposure to subtypes associated with highly pathogenic AIV. Our study provides further evidence of high seroprevalence in Arctic goose populations, and estimates of annual AIV seroconversion and antibody persistence for North American waterfowl. We suggest future AIV studies include serology to help elucidate the epizootiological dynamics of AIV in wild bird populations. PMID:26591451

  10. Dynamics of an SIQS epidemic model with transport-related infection and exit-entry screenings.

    PubMed

    Liu, Xianning; Chen, Xiaoping; Takeuchi, Yasuhiro

    2011-09-21

    Population dispersal, as a common phenomenon in human society, may cause the spreading of many diseases such as influenza, SARS, etc. which are easily transmitted from one region to other regions. Exit and entry screenings at the border are considered as effective ways for controlling the spread of disease. In this paper, the dynamics of an SIQS model are analyzed and the combined effects of transport-related infection enhancing and exit-entry screenings suppressing on disease spread are discussed. The basic reproduction number is computed and proved to be a threshold for disease control. If it is not greater than the unity, the disease free equilibrium is globally asymptotically stable. And there exists an endemic equilibrium which is locally asymptotically stable if the reproduction number is greater than unity. It is shown that the disease is endemic in the sense of permanence if and only if the endemic equilibrium exists. Exit screening and entry screening are shown to be helpful for disease eradication since they can always have the possibility to eradicate the disease endemic led by transport-related infection and furthermore have the possibility to eradicate disease even when the isolated cites are disease endemic. PMID:21740917

  11. The dynamics of avian influenza in Lesser Snow Geese: implications for annual and migratory infection patterns.

    PubMed

    Samuel, Michael D; Hall, Jeffrey S; Brown, Justin D; Goldberg, Diana R; Ip, Hon; Baranyuk, Vasily V

    2015-10-01

    Wild water birds are the natural reservoir for low-pathogenic avian influenza viruses (AIV). However, our ability to investigate the epizootiology of AIV in these migratory populations is challenging and, despite intensive worldwide surveillance, remains poorly understood. We conducted a cross-sectional, retrospective analysis in Pacific Flyway Lesser Snow Geese, Chen caerulescens, to investigate AIV serology and infection patterns. We collected nearly 3000 sera samples from Snow Geese at two breeding colonies in Russia and Canada during 1993-1996 and swab samples from >4000 birds at wintering and migration areas in the United States during 2006-2011. We found seroprevalence and annual seroconversion varied considerably among years. Seroconversion and infection rates also differed between Snow Goose breeding colonies and wintering areas, suggesting that AIV exposure in this gregarious waterfowl species is likely occurring during several phases (migration, wintering, and potentially breeding areas) of the annual cycle. We estimated AIV antibody persistence was longer (14 months) in female geese compared to males (6 months). This relatively long period of AIV antibody persistence suggests that subtype-specific serology may be an effective tool for detection of exposure to subtypes associated with highly pathogenic AIV. Our study provides further evidence of high seroprevalence in Arctic goose populations, and estimates of annual AIV seroconversion and antibody persistence for North American waterfowl. We suggest future AIV studies include serology to help elucidate the epizootiological dynamics of AIV in wild bird populations.

  12. Communication: Microsecond dynamics of the protein and water affect electron transfer in a bacterial bc1 complex

    NASA Astrophysics Data System (ADS)

    Martin, Daniel R.; Matyushov, Dmitry V.

    2015-04-01

    Cross-membrane electron transport between cofactors localized in proteins of mitochondrial respiration and bacterial photosynthesis is the source of all biological energy. The statistics and dynamics of nuclear fluctuations in these protein/membrane/water heterogeneous systems are critical for their energetic efficiency. The results of 13 μs of atomistic molecular dynamics simulations of the membrane-bound bc1 bacterial complex are analyzed here. The reaction is affected by a broad spectrum of nuclear modes, with the slowest dynamics in the range of time-scales ˜0.1-1.6 μs contributing half of the reaction reorganization energy. Two reorganization energies are required to describe protein electron transfer due to dynamical arrest of protein conformations on the observation window. This mechanistic distinction allows significant lowering of activation barriers for reactions in proteins.

  13. Communication: Microsecond dynamics of the protein and water affect electron transfer in a bacterial bc{sub 1} complex

    SciTech Connect

    Martin, Daniel R.; Matyushov, Dmitry V.

    2015-04-28

    Cross-membrane electron transport between cofactors localized in proteins of mitochondrial respiration and bacterial photosynthesis is the source of all biological energy. The statistics and dynamics of nuclear fluctuations in these protein/membrane/water heterogeneous systems are critical for their energetic efficiency. The results of 13 μs of atomistic molecular dynamics simulations of the membrane-bound bc{sub 1} bacterial complex are analyzed here. The reaction is affected by a broad spectrum of nuclear modes, with the slowest dynamics in the range of time-scales ∼0.1-1.6 μs contributing half of the reaction reorganization energy. Two reorganization energies are required to describe protein electron transfer due to dynamical arrest of protein conformations on the observation window. This mechanistic distinction allows significant lowering of activation barriers for reactions in proteins.

  14. Depletion of CD8+ cells does not affect the lifespan of productively infected cells during pathogenic sivmac239 infection of rhesus macaques

    SciTech Connect

    Shudo, Emi; Ribeiro, Ruy M; Perelson, Alan S

    2008-01-01

    While CD8+ T cell responses are clearly important in anti-viral immunity during HIV/SIV infection, the mechanisms by which CD8+ T cells induce this effect remain poorly understood, as emphasized by the failure of the Merck adenovirus-based, cytotoxic T lymphocyte (CTL)-inducing AIDS vaccine in a large phase IIb clinical trial. In this study, we measured the in vivo effect of CD8+ lymphocytes on the lifespan of productively infected cells during chronic SIVmac239 infection of rhesus macaques by treating two groups of animals (i.e., CD8+ lymphocyte-depleted or controls) with antiretroviral therapy (PMPA and FTC). The lifespan of productively infected cells was calculated based on the slope of the decline of SIV plasma viremia using a well-accepted mathematical model. We found that, in both early (i.e., day 57 post-inoculation) and late (i.e., day 177 post-inoculation) chronic SIV infection, depletion of CD8+ lymphocytes did not result in an increased lifespan of productively infected cells in vivo. This result indicates that direct killing of cells producing virus is unlikely to be a major mechanism underlying the anti-viral effect of CD8+ T cells during SIV infection. These results have profound implications for the development of AIDS vaccines.

  15. Woodland Patch Dynamics Affected by Oak Growth: Fire, Climate, and Human Influences

    NASA Astrophysics Data System (ADS)

    Murray, D. B.; White, J. D.

    2010-12-01

    Woodland fragmentation and aggregation occur due to impacts of fire, climate, and human factors. In our study we investigate the growth response of a deciduous oak species, Quercus buckleyii (Texas Red Oak) within a juniper-dominated woodland. This species may be a sentinel species for woodland patch developmental processes that could be used as a proxy for woodland patch contraction and expansion events. In this study, we used tree rings, fire scar, and multi-temporal aerial photographic data to assess response of oaks to disturbance type and resultant impact on woodland patches. Three hundred and seventy tree slabs from downed and dead red oaks were collected in the Balcones National Wildlife Refuge outside Austin, Texas. We analyzed tree rings from these slabs to determine recruitment date, annual ring width, and where evident, time of fire. Changes in tree ring widths associated with canopy openings were derived from neighborhood analysis of digital aerial photos from 1939, 1951, 1964, 1980, 1995, and 2004. Results indicated that red oaks increased radial growth following fire. Analysis of canopy openings associated with the aerial photographs showed that the oak species did not respond to canopy openings with increased radial growth as predicted by gap-phase dynamics. Climate impacted average radial ring growth as demonstrated by comparison with the Palmer Drought Severity and Nino 3 Index values (p = .56). Given that radial growth is influenced by both fire and climate, we explored the possibility that dramatic climate and related disturbance events (drought and high occurrence of fire) of the 1950’s created a possible ecological regime shift. Changes in both index value variance and disturbance frequency were noted during the 1950’s. These results were confirmed by landscape analysis of disturbance patches identified from the historical photographs which show cutting and burning occurred with the highest frequency between 1951 and 1964 with 70% of the

  16. Dynamic Visualizations: How Attraction, Motivation and Communication Affect Streaming Video Tutorial Implementation

    ERIC Educational Resources Information Center

    Boger, Claire

    2011-01-01

    The rapid advancement in the capabilities of computer technologies has made it easier to design and deploy dynamic visualizations in web-based learning environments; yet, the implementation of these dynamic visuals has been met with mixed results. While many guidelines exist to assist instructional designers in the design and application of…

  17. Population dynamics of three aphid species (Hemiptera: Aphididae) on four Ipomoea spp. infected or noninfected with sweetpotato potyviruses.

    PubMed

    Wosula, E N; Davis, J A; Clark, C A

    2013-08-01

    Three aphid species, Aphis gossypii Glover and Myzus persicae (Sulzer) (efficient sweetpotato potyvirus vectors) and Rhopalosiphum padi (L.) (an inefficient vector), are commonly found in sweet potato, Ipomoea batatas (L.), in Louisiana. Field-grown sweet potatoes are naturally infected with several potyviruses: Sweet potato feathery mottle virus, Sweet potato virus G, and Sweet potato virus 2. Thus, these aphids commonly encounter virus-infected hosts. What is not known is how each of these aphids responds to sweet potato, either infected or virus-free. The objectives of this study were to 1) determine if these aphid species can colonize mixed virus-infected sweet potato 'Beauregard', and if so, 2) determine the effects of virus infection on the population dynamics of each aphid. A. gossypii failed to larviposit and R. padi deposited a single nymph that died within a day on mixed virus-infected Beauregard. M. persicae larviposited and colonized Beauregard and further life-table analyses were warranted. M. persicae had a significantly greater reproduction on sweet potato cultivars Beauregard and 'Evangeline' with mixed virus infection compared with noninfected plants. On morning glory species, Ipomoea cordatotriloba (Dennestedt) and Ipomoea hederacea (Jacquin), M. persicae had a significantly lower reproduction on Sweet potato feathery mottle virus-infected compared with noninfected plants.

  18. Population dynamics of three aphid species (Hemiptera: Aphididae) on four Ipomoea spp. infected or noninfected with sweetpotato potyviruses.

    PubMed

    Wosula, E N; Davis, J A; Clark, C A

    2013-08-01

    Three aphid species, Aphis gossypii Glover and Myzus persicae (Sulzer) (efficient sweetpotato potyvirus vectors) and Rhopalosiphum padi (L.) (an inefficient vector), are commonly found in sweet potato, Ipomoea batatas (L.), in Louisiana. Field-grown sweet potatoes are naturally infected with several potyviruses: Sweet potato feathery mottle virus, Sweet potato virus G, and Sweet potato virus 2. Thus, these aphids commonly encounter virus-infected hosts. What is not known is how each of these aphids responds to sweet potato, either infected or virus-free. The objectives of this study were to 1) determine if these aphid species can colonize mixed virus-infected sweet potato 'Beauregard', and if so, 2) determine the effects of virus infection on the population dynamics of each aphid. A. gossypii failed to larviposit and R. padi deposited a single nymph that died within a day on mixed virus-infected Beauregard. M. persicae larviposited and colonized Beauregard and further life-table analyses were warranted. M. persicae had a significantly greater reproduction on sweet potato cultivars Beauregard and 'Evangeline' with mixed virus infection compared with noninfected plants. On morning glory species, Ipomoea cordatotriloba (Dennestedt) and Ipomoea hederacea (Jacquin), M. persicae had a significantly lower reproduction on Sweet potato feathery mottle virus-infected compared with noninfected plants. PMID:24020267

  19. Allee effect in the infection dynamics of the entomopathogenic Fungus Beauveria bassiana (Bals) Vuill. on the beetle, Mylabris pustulata.

    PubMed

    Devi, K Uma; Rao, C Uma Maheswara

    2006-06-01

    Successful infection by Beauveria bassiana as with all other entomopathogenic fungi, is accomplished only at a high conidial dose while, theoretically, a single conidium should be sufficient. Indeed, this is a major deterrent in its use as a biocontrol agent. High pathogen load for infection is required by organisms which display 'Allee' effect. In such organisms, a threshold exists for pathogen dose, below which no infection can be caused. B. bassiana has a semelparous life cycle and, therefore, its infection dynamics are expected to conform to the mass action principle with a linear relationship between dose and successful infection observable as mortality of the insect. Whether the need for a high conidial dose to induce insect mortality by B. bassiana is due to the operation of Allee effect was examined. A sample of 34 isolates was bioassayed on Mylabris pustulata (Coleoptera: Meloidae) at four conidial concentrations. With more than half of the isolates in the sample, the lowest dose tested (10(4) conidia/insect) did not cause insect mortality. Thus, a threshold pathogen load is required to cause successful infection. In these isolates, the dose-mortality relationship was sigmoid. Allee effect is thus identified in the infection dynamics of B. bassiana-M. pustulata system. The isolates that induced mortality at the lowest dose tested are concluded to be highly virulent with a lower threshold dose required for successful infection. With some isolates, at high conidial dose, the infection rate decreased either due to a decrease in the proportion of insects showing mycosis, to the speed of death, or both. Such a response could result from intra scramble competition arising from overload of pathogen at very high dose.

  20. Allee effect in the infection dynamics of the entomopathogenic Fungus Beauveria bassiana (Bals) Vuill. on the beetle, Mylabris pustulata.

    PubMed

    Devi, K Uma; Rao, C Uma Maheswara

    2006-06-01

    Successful infection by Beauveria bassiana as with all other entomopathogenic fungi, is accomplished only at a high conidial dose while, theoretically, a single conidium should be sufficient. Indeed, this is a major deterrent in its use as a biocontrol agent. High pathogen load for infection is required by organisms which display 'Allee' effect. In such organisms, a threshold exists for pathogen dose, below which no infection can be caused. B. bassiana has a semelparous life cycle and, therefore, its infection dynamics are expected to conform to the mass action principle with a linear relationship between dose and successful infection observable as mortality of the insect. Whether the need for a high conidial dose to induce insect mortality by B. bassiana is due to the operation of Allee effect was examined. A sample of 34 isolates was bioassayed on Mylabris pustulata (Coleoptera: Meloidae) at four conidial concentrations. With more than half of the isolates in the sample, the lowest dose tested (10(4) conidia/insect) did not cause insect mortality. Thus, a threshold pathogen load is required to cause successful infection. In these isolates, the dose-mortality relationship was sigmoid. Allee effect is thus identified in the infection dynamics of B. bassiana-M. pustulata system. The isolates that induced mortality at the lowest dose tested are concluded to be highly virulent with a lower threshold dose required for successful infection. With some isolates, at high conidial dose, the infection rate decreased either due to a decrease in the proportion of insects showing mycosis, to the speed of death, or both. Such a response could result from intra scramble competition arising from overload of pathogen at very high dose. PMID:16761186

  1. Genetically different isolates of Trypanosoma cruzi elicit different infection dynamics in raccoons (Procyon lotor) and Virginia opossums (Didelphis virginiana).

    PubMed

    Roellig, Dawn M; Ellis, Angela E; Yabsley, Michael J

    2009-12-01

    Trypanosoma cruzi is a genetically and biologically diverse species. In the current study we determined T. cruzi infection dynamics in two common North American reservoirs, Virginia opossums (Didelphis virginiana) and raccoons (Procyon lotor). Based on previous molecular and culture data from naturally-exposed animals, we hypothesised that raccoons would have a longer patent period than opossums, and raccoons would be competent reservoirs for both genotypes T. cruzi I (TcI) and TcIIa, while opossums would only serve as hosts for TcI. Individuals (n=2 or 3) of each species were inoculated with 1x10(6) culture-derived T. cruzi trypomastigotes of TcIIa (North American (NA) - raccoon), TcI (NA - opossum), TcIIb (South American - human), or both TcI and TcIIa. Parasitemias in opossums gradually increased and declined rapidly, whereas parasitemias peaked sooner in raccoons and they maintained relatively high parasitemia for 5weeks. Raccoons became infected with all three T. cruzi strains, while opossums only became infected with TcI and TcIIb. Although opossums were susceptible to TcIIb, infection dynamics were dramatically different compared with TcI. Opossums inoculated with TcIIb seroconverted, but parasitemia duration was short and only detectable by PCR. In addition, raccoons seroconverted sooner (3-7days post inoculation) than opossums (10days post inoculation). These data suggest that infection dynamics of various T. cruzi strains can differ considerably in different wildlife hosts.

  2. Methamphetamine Use in HIV-infected Individuals Affects T-cell Function and Viral Outcome during Suppressive Antiretroviral Therapy

    PubMed Central

    Massanella, Marta; Gianella, Sara; Schrier, Rachel; Dan, Jennifer M.; Pérez-Santiago, Josué; Oliveira, Michelli F.; Richman, Douglas D.; Little, Susan J.; Benson, Constance A.; Daar, Eric S.; Dube, Michael P.; Haubrich, Richard H.; Smith, Davey M.; Morris, Sheldon R.

    2015-01-01

    We investigated the associations between methamphetamine (meth) use, immune function, and the dynamics of HIV and cytomegalovirus [CMV] in the blood and genital tract of HIV-infected ART-suppressed subjects. Self-reported meth use was associated with increased CD4+ and CD8+ T-cell proliferation (Ki67+, p < 0.005), CD4+ T-cell activation (CD45RA–CD38+, p = 0.005) and exhaustion (PD-1+, p = 0.0004) in blood, compared to non-meth users. Meth use was also associated with a trend towards higher blood HIV DNA levels (p = 0.09) and more frequent shedding of CMV in seminal plasma (p = 0.002). To explore possible mechanisms, we compared ex vivo spontaneous and antigen-specific proliferation in PBMC collected from subjects with and without positive meth detection in urine (Utox+ vs. Utox-). Despite higher levels of spontaneous proliferation, lymphocytes from Utox+ meth users had a significantly lower proliferative capacity after stimulation with a number of pathogens (CMV, candida, mycobacterium, toxoplasma, HIV, p < 0.04 in all cases), compared to Utox- participants. Our findings suggest that meth users have greater proliferation and exhaustion of the immune system. Meth use is also associated with a loss of control of CMV replication, which could be related to loss of immune response to pathogens. Future studies should consider meth use as a potential modulator of T-cell responses. PMID:26299251

  3. Experimental Infection of Ornithodoros erraticus sensu stricto with Two Portuguese African Swine Fever Virus Strains. Study of Factors Involved in the Dynamics of Infection in Ticks.

    PubMed

    Ribeiro, Rita; Otte, Joachim; Madeira, Sara; Hutchings, Geoff H; Boinas, Fernando

    2015-01-01

    African swine fever (ASF) is a frequently devastating hemorrhagic disease of domestic pigs and wild boar and Ornithodoros erraticus sensu stricto argasid ticks are the only biological vectors of African swine fever virus (ASFV) known to occur in Europe. Recently this disease emerged in Eastern Europe and Russian Federation, showing a huge potential for a rapid spread between countries. There is some risk of re-emergence of ASF in the countries where these ticks exist, that can contribute for the persistence of infection and compromise control measures. In this study we aimed to identify factors that determine the probability of infection and its dynamics in the tick vector Ornithodoros erraticus sensu stricto, with two Portuguese strains of ASFV. Our results suggest that these ticks have a high likelihood of excreting the two haemadsorbing ASF viruses of different host origins and that, in field surveys, the analysis of adults and 5th nymphal stage can provide the best chance of detecting virus infection. The results also indicate that infection of pigs with highly virulent ASF viruses will promote higher rates of infection and a higher likelihood for virus excretion by ticks. Nevertheless, there is also a risk, although lower, that ticks can become infected on pigs that have overcome the acute phase of infection, which was simulated in our study by membrane feeding ticks with low titres of virus. We believe these results can be valuable in designing and interpreting the results of ASF control programmes, and future work can also be undertaken as our dataset is released under open access, to perform studies in risk assessment for ASFV persistence in a region where O. erraticus sensu stricto ticks are present. PMID:26366570

  4. Experimental Infection of Ornithodoros erraticus sensu stricto with Two Portuguese African Swine Fever Virus Strains. Study of Factors Involved in the Dynamics of Infection in Ticks

    PubMed Central

    Madeira, Sara; Hutchings, Geoff H.; Boinas, Fernando

    2015-01-01

    African swine fever (ASF) is a frequently devastating hemorrhagic disease of domestic pigs and wild boar and Ornithodoros erraticus sensu stricto argasid ticks are the only biological vectors of African swine fever virus (ASFV) known to occur in Europe. Recently this disease emerged in Eastern Europe and Russian Federation, showing a huge potential for a rapid spread between countries. There is some risk of re-emergence of ASF in the countries where these ticks exist, that can contribute for the persistence of infection and compromise control measures. In this study we aimed to identify factors that determine the probability of infection and its dynamics in the tick vector Ornithodoros erraticus sensu stricto, with two Portuguese strains of ASFV. Our results suggest that these ticks have a high likelihood of excreting the two haemadsorbing ASF viruses of different host origins and that, in field surveys, the analysis of adults and 5th nymphal stage can provide the best chance of detecting virus infection. The results also indicate that infection of pigs with highly virulent ASF viruses will promote higher rates of infection and a higher likelihood for virus excretion by ticks. Nevertheless, there is also a risk, although lower, that ticks can become infected on pigs that have overcome the acute phase of infection, which was simulated in our study by membrane feeding ticks with low titres of virus. We believe these results can be valuable in designing and interpreting the results of ASF control programmes, and future work can also be undertaken as our dataset is released under open access, to perform studies in risk assessment for ASFV persistence in a region where O. erraticus sensu stricto ticks are present. PMID:26366570

  5. Infection dynamics of coexisting beta- and gammaproteobacteria in the nested endosymbiotic system of mealybugs.

    PubMed

    Kono, Marie; Koga, Ryuichi; Shimada, Masakazu; Fukatsu, Takema

    2008-07-01

    We investigated the infection dynamics of endosymbiotic bacteria in the developmental course of the mealybugs Planococcus kraunhiae and Pseudococcus comstocki. Molecular phylogenetic analyses identified a betaproteobacterium and a gammaproteobacterium from each of the mealybug species. The former bacterium was related to the beta-endosymbionts of other mealybugs, i.e., "Candidatus Tremblaya princeps," and formed a compact clade in the Betaproteobacteria. Meanwhile, the latter bacterium was related to the gamma-endosymbionts of other mealybugs but belonged to distinct clades in the Gammaproteobacteria. Whole-mount in situ hybridization confirmed the peculiar nested formation in the endosymbiotic system of the mealybugs: the beta-endosymbiont cells were present in the cytoplasm of the bacteriocytes, and the gamma-endosymbiont cells were located in the beta-endosymbiont cells. In nymphal and female development, a large oval bacteriome consisting of a number of bacteriocytes was present in the abdomen, wherein the endosymbionts were harbored. In male development, strikingly, the bacteriome progressively degenerated in prepupae and pupae and became almost unrecognizable in adult males. In the degeneration process, the gamma-endosymbionts disappeared more rapidly than the beta-endosymbionts did. Quantitative PCR analyses revealed that (i) the population dynamics of the endosymbionts in female development reflected the reproductive activity of the insects, (ii) the population dynamics of the endosymbionts were strikingly different between female development and male development, (iii) the endosymbiont populations drastically decreased in male development, and (iv) the gamma-endosymbiont populations decreased more rapidly than the beta-endosymbiont populations in male development. Possible mechanisms underlying the uncoupled regulation of the beta- and gamma-endosymbiont populations are discussed in relation to the establishment and evolution of this unique prokaryote

  6. Modeling susceptible infective recovered dynamics and plague persistence in California rodent-flea communities.

    PubMed

    Foley, Patrick; Foley, Janet

    2010-01-01

    Plague persists as an enzootic in several very different rodent-flea communities around the world. In California, a diversity of rodent-flea communities maintains the disease, and a single-host reservoir seems unlikely. Logistic regression of plague presence on climate and topographic variables predicts plague in many localities where it is absent. Thus, a dynamic community-based analysis was needed. Deterministic Susceptible Infective Recovered (SIR) models were adapted for plague and analyzed with an eye for insights concerning disease persistence. An R simulation program, Plaguesirs, was developed incorporating multihost and multivector SIR dynamics, demographic and environmental stochasticity, density dependence, and seasonal variation in birth and death. Flea-rodent utilization matrices allowed us to get transmission rates as well as flea carrying capacities. Rodent densities allowed us to estimate host carrying capacities, while maximum birth rates were mainly approximated through an examination of litter phenology and demography. We ran a set of simulations to assess the role of community structure in maintaining plague in a simulated version of Chuchupate campground in Ventura County. Although the actual campground comprises 10 rodent and 19 flea species, we focused on a subset suspected to act as a reservoir community. This included the vole Microtus californicus, the deer mouse Peromyscus maniculatus, the Ceratophyllid fleas Aetheca wagneri and Malareus telchinum, and the Leptopsyllid flea Peromyscopsylla hesperomys. The dynamics of 21 subsets of this community were simulated for 20 years. Single-rodent communities showed much lower disease persistence than two-rodent communities. However, so long as Malareus was present, endemicity was enhanced; removal of the other two fleas slightly increased disease persistence. Two critical features improved disease persistence: (1) host breeding season heterogeneity and (2) host population augmentation (due to two

  7. Dynamic changes in circulating and antigen-responsive T-cell subpopulations post-Mycobacterium bovis infection in cattle.

    PubMed Central

    Pollock, J M; Pollock, D A; Campbell, D G; Girvin, R M; Crockard, A D; Neill, S D; Mackie, D P

    1996-01-01

    Bovine tuberculosis is a threat to animal and human health in several countries. Greater understanding of the immunology of the disease is required to develop improved tests and vaccines. This study has used a model of bovine tuberculosis, established in the natural host, to investigate the dynamic changes that occur in the circulating T-cell subpopulations after infection. When the phenotypic composition of the peripheral blood lymphocytes was determined pre- and post-experimental infection, the response to disease comprised three phases. Firstly, the WC1/gamma delta T cells decreased and then increased, suggesting localization to developing lesions and clonal expansion. Secondly, the CD4:CD8 ratio increased. Thirdly, the CD4:CD8 ratio decreased to less than pre-infection measurements. The latter changes suggested sequential involvement of CD4 and then CD8 T cells. The proportion of cells expressing interleukin-2 receptor (IL-2R) also increased. Panels of T-cell clones were established at various stages post-infection and all clones that exhibited antigen responsiveness were phenotyped. T-cell clones from early infection were WC1/gamma delta and CD4 in phenotype, while CD8 clones appeared later in infection, eventually becoming dominant. Therefore, from in vivo and in vitro evidence, it was suggested that there is a dynamic progression in the T-cell subpopulations involved dominantly in responses to mycobacteria. PMID:8698385

  8. Cellular automata approach for the dynamics of HIV infection under antiretroviral therapies: The role of the virus diffusion

    NASA Astrophysics Data System (ADS)

    González, Ramón E. R.; de Figueirêdo, Pedro Hugo; Coutinho, Sérgio

    2013-10-01

    We study a cellular automata model to test the timing of antiretroviral therapy strategies for the dynamics of infection with human immunodeficiency virus (HIV). We focus on the role of virus diffusion when its population is included in previous cellular automata model that describes the dynamics of the lymphocytes cells population during infection. This inclusion allows us to consider the spread of infection by the virus-cell interaction, beyond that which occurs by cell-cell contagion. The results show an acceleration of the infectious process in the absence of treatment, but show better efficiency in reducing the risk of the onset of AIDS when combined antiretroviral therapies are used even with drugs of low effectiveness. Comparison of results with clinical data supports the conclusions of this study.

  9. Numerical modelling of a healthy/malaria-infected erythrocyte in shear flow using dissipative particle dynamics method

    NASA Astrophysics Data System (ADS)

    Ye, Ting; Phan-Thien, Nhan; Cheong Khoo, Boo; Teck Lim, Chwee

    2014-06-01

    In the present paper, the dynamics of healthy and malaria-infected erythrocytes in the shear flow are investigated using dissipative particle dynamics (DPD), a particle-based method. A discrete model is developed, where the computational domain is discretized into a set of particles to represent the suspending liquid, as well as erythrocytes as suspended deformable particles. The particles on an erythrocyte surface are connected into a triangular network to represent the membrane. The interaction between any two particles is modelled by the DPD method, which conserves both mass and momentum. In order to validate this model, the deformation of a spherical capsule in the shear flow is firstly simulated, and a good agreement is found with previously published works. Then, the dynamics of a healthy biconcave erythrocyte in a shear flow is investigated. The results demonstrate that a healthy erythrocyte undergoes a tank-treading motion at a high capillary number, and a tumbling motion at a low capillary number or at a high viscosity ratio, internal (erythrocyte) to external fluids. Two other types of trembling motions, breathing with tumbling and swinging with tank-treading, are also found at an intermediate capillary number or viscosity ratio. Finally, the dynamics of malaria-infected erythrocyte in a shear flow is studied. At the same shear rate, if the healthy erythrocyte undergoes a tumbling motion, the malaria-infected one will exhibit a tumbling motion only. If the healthy erythrocyte undergoes a trembling motion, the malaria-infected one cannot exhibit tank-treading motion. If the healthy erythrocyte undergoes a tank-treading motion, the malaria-infected one will exhibit one of three dynamic motions: tumbling, trembling or tank-treading motion.

  10. Neutrophil dynamics in the blood and milk of crossbred cows naturally infected with Staphylococcus aureus

    PubMed Central

    Swain, Dilip K.; Kushwah, Mohar Singh; Kaur, Mandheer; Dang, Ajay K.

    2015-01-01

    Aim: The present study was designed to evaluate the neutrophil dynamics in terms of the functional competence during subclinical mastitis (SCM) and clinical mastitis (CM). Materials and Methods: A total of 146 Karan fries cows were screened and were divided into three groups as control (n=12), SCM, n=12 and CM, n=12 groups on the basis of California mastitis test scoring, bacteriological evaluation, gross and morphological changes in milk and by counting milk somatic cell count (SCC). Both blood and milk polymorphonuclear neutrophils (PMNs) were isolated in the study. Phagocytic activity (PA) was studied by spectrophotometrically; neutrophil extracelluar traps (NETs) were studied by scanning electron microscopy (SEM); CD44 was quantified by flow cytometry and apoptosis was studied by fluorescent microscopy. Results: Significantly (p<0.05) higher SCC, PA was found in milk of CM cows as compared to SCM and control cows. Significantly lower (p<0.05) apoptosis was observed in PMNs isolated from both blood and milk of CM group of cows when compared to control and SCM group. The milk neutrophils of CM group of cows formed NETs as evidenced from the SEM images. Surface expression of CD44 revealed a significantly (p<0.05) lower expression in milk neutrophils of CM group of cows when compared to SCM and control group of cows. Conclusion: The study indicated a positive correlation between delayed neutrophil apoptosis, persistent staying of neutrophils at the site of infection along with formation of NETs as the strategies to fight against the pathogens in the udder during Staphylococcal mastitis. The study forms a strong base for future molecular research in terms of neutrophil recruitment and neutrophil removal from the site of infection. PMID:27047094

  11. Paramphistomum daubneyi: production dynamics and infectivity of metacercariae originating from snails dissected at regular intervals.

    PubMed

    Vignoles, P; Rondelaud, D; Dreyfuss, G

    2008-06-01

    Experimental infections of Galba truncatula with Paramphistomum daubneyi were carried out at 24 degrees C to study the dynamics of larval development in snails dissected at regular intervals and to determine if metacercarial production might be improved. When the shell height of snails (4, 5, 6 or 7 mm) at exposure increased (experiment A), the total number of metacercariae was significantly higher in the 6- and 7-mm snails than in the other two groups, and the differentiation period was shortened (the first cercariae encysted at day 35 post-exposure (p.e.) instead of day 40 in the 4- and 5-mm groups). When the number of miracidia (two, three or five) for each 6-mm high G. truncatula increased (experiment B), a significant decrease of snail survival at day 30 p.e., a significant augmentation of prevalence, and a significant increase of metacercarial production were noted. In the two- and three-miracidium groups, the number of metacercariae was close to that found in the 6-mm snails from experiment 1, whereas they showed slower growth from day 45 to day 65 in the five-miracidium group. In the two groups of lambs infected with metacercariae encysted at days 45 or 60 p.e., no difference in the numbers of adult worms was noted. In contrast, in the case of 35-day encysted larvae, the number of adult worms was clearly lower. Snail dissection allowed higher metacercarial production, a saving of 12-15 days at 24 degrees C to obtain these larvae, and a substantial decrease of their cost price for commercial production. PMID:18328114

  12. Ecological Dynamics of Two Distinct Viruses Infecting Marine Eukaryotic Decomposer Thraustochytrids (Labyrinthulomycetes, Stramenopiles).

    PubMed

    Takao, Yoshitake; Tomaru, Yuji; Nagasaki, Keizo; Honda, Daiske

    2015-01-01

    Thraustochytrids are cosmopolitan osmotrophic or heterotrophic microorganisms that are considered as important decomposers in coastal ecosystems. However, because of a lack of estimation method for each genus or systematic group of them, relatively little is known about their ecology in situ. Previously, we reported two distinct types of virus infecting thraustochytrids (AuRNAV: reported as SssRNAV, and SmDNAV) suggesting they have wide distributions in the host-virus systems of coastal environments. Here we conducted a field survey from 2004 through 2005 to show the fluctuation pattern of thraustochytrids and their viruses in Hiroshima Bay, Japan. During the field survey, we monitored the dynamics of the two types of thraustochytrid-infecting virus: small viruses causing lysis of Aurantiochytrium sp. NIBH N1-27 (identified as AuRNAV) and the large viruses of Sicyoidochytrium minutum NBRC 102975 (similar to SmDNAV in physiology and morphology). Fluctuation patterns of the two distinct types of virus were different from each other. This may reflect the difference in the preference of organic substrates; i.e., it may be likely the host of AuRNAV (Aurantiochytrium sp.) increases utilizing algal dead bodies or feeble cells as the virus shows a large increase in abundance following raphidophyte blooms; wherea