3,205 research outputs found
The effects of classic and variant infectious bursal disease viruses on lymphocyte populations in specific-pathogen-free White Leghorn chickens
Infectious bursal disease virus (IBDV) is a pathogen that primarily infects B lymphocytes in domestic avian species. This viral infection has been associated with immunosuppression, clinical disease/mortality, and enteric malabsorption effects. The purpose of this experiment was to compare the effects of a classic (USDA-STC) and a new variant IBDV (RB-4, known to induce primarily the enteric disease) on immune cell populations in lymphoid organs. Seventeen-dayold specific-pathogen-free (SPF) White Leghorn chickens were either not infected (control) or inoculated with either USDA-STC or RB-4 IBD viral isolate. On days 3 and 5 post-inoculation (PI), lymphoid tissues were collected to prepare cell suspensions for immunofluorescent staining and cell population analysis by flow cytometry. Portions of the tissues were snap frozen for immunohistochemistry to localize various immune cells and IBD virus in the tissues. Tissue homogenates were prepared to test for IBDV by quantitative MTT assay. Both the USDA-STC and RB-4 viruses greatly altered lymphocyte populations in the spleen and bursa. At 5 d PI, bursal B cells were approximately 25% and 60% of lymphocytes in chicks infected with USDA-STC and RB-4, respectively, whereas in control birds, B cells constituted 99% of bursal lymphocytes. This reduction in the proportions of bursal B cells was associated with an infiltration of T cells. In the spleen, IBDV infection also reduced the percentage of B cells and increased the percentage of T cells. The differential effects of classic and variant IBDV infection on immune cell populations in lymphoid organs may explain the differences in clinical effects induced by these viruse
An Effective Chemical Deterrent for Invasive Cuban Treefrogs
Introduced vertebrates have a variety of impacts on ecosystems and economies, and many cause problems for humans. One such problem is the loss of electrical power when invasive animals cause short circuits in power-transmission equipment. Cuban treefrogs (Osteopilus septentrionalis) are known to cause power outages and are a nuisance to humans when they invade homes and defecate on doors and windows. These large, slightly toxic treefrogs were introduced into Florida from the Caribbean. They now occur throughout the peninsula of Florida and are spreading to other states in the Southeast. We used refuge choice experiments to test the effectiveness of Sniff ’n’ StopTM animal deterrent to exclude Cuban treefrogs from enclosed spaces, such as utility switchgear boxes. We found that the deterrent was effective and showed potential as a low-cost means to prevent frog-related power outages and reduce conflicts with residents in the urbanized areas preferred by these invasive frog
Time-Dependent Propensity Score for Assessing the Effect of Vaccine Exposure on Pregnancy Outcomes through Pregnancy Exposure Cohort Studies
Women are advised to be vaccinated for influenza during pregnancy and may receive vaccine at any time during their pregnancy. In observational studies evaluating vaccine safety in pregnancy, to account for such time-varying vaccine exposure, a time-dependent predictor can be used in a proportional hazards model setting for outcomes such as spontaneous abortion or preterm delivery. Also, due to the observational nature of pregnancy exposure cohort studies and relatively low event rates, propensity score (PS) methods are often used to adjust for potential confounders. Using Monte Carlo simulation experiments, we compare two different ways to model the PS for vaccine exposure: (1) logistic regression treating the exposure status as binary yes or no; (2) Cox regression treating time to exposure as time-to-event. Coverage probability of the nominal 95% confidence interval for the exposure effect is used as the main measure of performance. The performance of the logistic regression PS depends largely on how the exposure data is generated. In contrast, the Cox regression PS consistently performs well across the different data generating mechanisms that we have considered. In addition, the Cox regression PS allows adjusting for potential time-varying confounders such as season of the year or exposure to additional vaccines. The application of the Cox regression PS is illustrated using data from a recent study of the safety of pandemic H1N1 influenza vaccine during pregnancy
Interaction between Microtubules and the Drosophila Formin Cappuccino and Its Effect on Actin Assembly
Formin family actin nucleators are potential coordinators of the actin and microtubule cytoskeletons, as they can both nucleate actin filaments and bind microtubules in vitro. To gain a more detailed mechanistic understanding of formin-microtubule interactions and formin-mediated actin-microtubule cross-talk, we studied microtubule binding by Cappuccino (Capu), a formin involved in regulating actin and microtubule organization during Drosophila oogenesis. We found that two distinct domains within Capu, FH2 and tail, work together to promote high-affinity microtubule binding. The tail domain appears to bind microtubules through nonspecific charge-based interactions. In contrast, distinct residues within the FH2 domain are important for microtubule binding. We also report the first visualization of a formin polymerizing actin filaments in the presence of microtubules. Interestingly, microtubules are potent inhibitors of the actin nucleation activity of Capu but appear to have little effect on Capu once it is bound to the barbed end of an elongating filament. Because Capu does not simultaneously bind microtubules and assemble actin filaments in vitro, its actin assembly and microtubule binding activities likely require spatial and/or temporal regulation within the Drosophila oocyte
State Control and the Effects of Foreign Relations on Bilateral Trade
Can governments still use trade to reward and punish partner countries? While WTO rules and
the pressures of globalization restrict states’ capacity to manipulate trade policies, politicization of
trade is likely to occur where governments intervene in markets. We examine state ownership of firms
as one tool of government control. Taking China and India as examples, we use new data on imports
disaggregated by firm ownership type, as well as measures of political relations based on bilateral
events and UN voting data to estimate the effect of political relations on import flows since the early
1990s. Our results support the hypothesis that imports controlled by state-owned enterprises (SOEs)
are more responsive to political relations than imports controlled by private enterprises. This finding
suggests that politicized trade will increase as countries with partially state-controlled economies
gain strength in the global economy
Apego como marco teórico para entender los trastornos de personalidad: Consideraciones psicoterapéuticas, neurocientíficas y de desarrollo
In this paper we propose that John Bowlby\u27s attachment theory provides a theoretically coherent, empirically based, and clinically useful model for understanding personality pathology. This theoretical framework brings parsimony and breadth to the conceptualization of the etiology, maintenance, and treatment of personality disorders (PDs). Attachment theory can explain both the intrapersonal and interpersonal difficulties common in those with PDs and is consistent with findings from studies across multiple domains of knowledge, including evolutionary biology, ethology/comparative psychology, developmental psychology, experimental social-personality psychology, and neuroscience.PDs are characterized by significant interpersonal challenges. Recently, these challenges have been hypothesized to stem from underlying maladaptive attachment schemas. Our goal is to outline and elaborate on attachment theory as a foundation for the etiology and pathology of PDs and to highlight the implications of this theory for treatment. We begin with a brief review of attachment, describing its conceptualization and assessment in both children and adults in order to examine PD development. This theoretical foundation is supported by a body of empirical research, from which we present findings from neurobiological and developmental literatures linking attachment and PDs. We then examine the role of attachment in the psychotherapy process and in treatment outcome. Further, we outline research reporting changes in attachment patterns as a result of treatment. Finally, we summarize the implications of attachment theory for understanding PDs and present possible directions for future research.En este trabajo proponemos que la teoría de apego de John Bowlby ofrece un modelo teoréticamente coherente, empíricamente basado y clínicamente útil para entender la patología de personalidad. Este marco teorético trae parquedad y anchura a la conceptualización de la etiología, mantenimiento y tratamiento de trastornos de personalidad. La teoría de apego puede explicar las dificultades tanto intrapersonales como interpersonales comunes a las personas con trastornos de personalidad y es consistente con los descubrimientos de estudios de varios dominios del saber, incluyendo biología evolutiva, etiología/psicología comparada, psicología de desarrollo, psicología de personalidad y psicología social-personalidad experimental, y neurociencia.
Trastornos de personalidad son caracterizados por los retos interpersonales significativos. Últimamente, se han hecho hipótesis que estos retos son el resultado de esquemas de apego mal adaptivos. Nuestro objetivo es explicar y elaborar la teoría de apego como la base para la etiología y patología de trastornos de personalidad y acentuar las implicaciones de esta teoría para el tratamiento. Empezamos con un pequeño análisis del apego, describiendo sus conceptualizaciones y evaluación tanto en niños como adultos para examinar el desarrollo de trastornos de personalidad. Este fundamento teórico está apoyado por la investigación empírica, de la que presentamos resultados de la literatura neurobiológica y de desarrollo relacionados con el apego y los trastornos de personalidad. Luego investigamos el papel que tiene el apego en los procesos de psicoterapia y en los resultados del tratamiento. Finalmente, resumimos las implicaciones de la teoría de apego para entender trastornos de personalidad y presentamos unas posibles direcciones para las futuras investigaciones
Subclinical infection of macaques and baboons with a baboon simarterivirus
Simarteriviruses (Arteriviridae: Simarterivirinae) are commonly found at high titers in the blood of African monkeys but do not cause overt disease in these hosts. In contrast, simarteriviruses cause severe disease in Asian macaques upon accidental or experimental transmission. Here, we sought to better understand the host-dependent drivers of simarterivirus pathogenesis by infecting olive baboons (n = 4) and rhesus monkeys (n = 4) with the simarterivirus Southwest baboon virus 1 (SWBV-1). Surprisingly, none of the animals in our study showed signs of disease following SWBV-1 inoculation. Three animals (two rhesus monkeys and one olive baboon) became infected and sustained high levels of SWBV-1 viremia for the duration of the study. The course of SWBV-1 infection was highly predictable: plasma viremia peaked between 1 × 107 and 1 × 108 vRNA copies/mL at 3–10 days post-inoculation, which was followed by a relative nadir and then establishment of a stable set-point between 1 × 106 and 1 × 107 vRNA copies/mL for the remainder of the study (56 days). We characterized cellular and antibody responses to SWBV-1 infection in these animals, demonstrating that macaques and baboons mount similar responses to SWBV-1 infection, yet these responses are ineffective at clearing SWBV-1 infection. SWBV-1 sequencing revealed the accumulation of non-synonymous mutations in a region of the genome that corresponds to an immunodominant epitope in the simarterivirus major envelope glycoprotein GP5, which likely contribute to viral persistence by enabling escape from host antibodies
How Do Cytokines Trigger Genomic Instability?
Inflammation is a double-edged sword presenting a dual effect on cancer development, from one hand promoting tumor initiation and progression and from the other hand protecting against cancer through immunosurveillance mechanisms. Cytokines are crucial components of inflammation, participating in the interaction between the cells of tumor microenvironment. A comprehensive study of the role of cytokines in the context of the inflammation-tumorigenesis interplay helps us to shed light in the pathogenesis of cancer. In this paper we focus on the role of cytokines in the development of genomic instability, an evolving hallmark of cancer
- …