465 research outputs found

    Geographically touring the eastern bloc: British geography, travel cultures and the Cold War

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    This paper considers the role of travel in the generation of geographical knowledge of the eastern bloc by British geographers. Based on oral history and surveys of published work, the paper examines the roles of three kinds of travel experience: individual private travels, tours via state tourist agencies, and tours by academic delegations. Examples are drawn from across the eastern bloc, including the USSR, Poland, Romania, East Germany and Albania. The relationship between travel and publication is addressed, notably within textbooks, and in the Geographical Magazine. The study argues for the extension of accounts of cultures of geographical travel, and seeks to supplement the existing historiography of Cold War geography

    Modulation of hepatic PPAR expression during Ft LVS LPS-induced protection from Francisella tularensis LVS infection

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    <p>Abstract</p> <p>Background</p> <p>It has been shown previously that administration of <it>Francisella tularensis </it>(<it>Ft</it>) Live Vaccine Strain (LVS) lipopolysaccharide (LPS) protects mice against subsequent challenge with <it>Ft </it>LVS and blunts the pro-inflammatory cytokine response.</p> <p>Methods</p> <p>To further investigate the molecular mechanisms that underlie <it>Ft </it>LVS LPS-mediated protection, we profiled global hepatic gene expression following <it>Ft </it>LVS LPS or saline pre-treatment and subsequent <it>Ft </it>LVS challenge using Affymetrix arrays.</p> <p>Results</p> <p>A large number of genes (> 3,000) were differentially expressed at 48 hours post-infection. The degree of modulation of inflammatory genes by infection was clearly attenuated by pre-treatment with <it>Ft </it>LVS LPS in the surviving mice. However, <it>Ft </it>LVS LPS alone had a subtle effect on the gene expression profile of the uninfected mice. By employing gene set enrichment analysis, we discovered significant up-regulation of the fatty acid metabolism pathway, which is regulated by peroxisome proliferator activated receptors (PPARs).</p> <p>Conclusions</p> <p>We hypothesize that the LPS-induced blunting of pro-inflammatory response in mouse is, in part, mediated by PPARs (Ξ± and Ξ³).</p

    Effective, Broad Spectrum Control of Virulent Bacterial Infections Using Cationic DNA Liposome Complexes Combined with Bacterial Antigens

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    Protection against virulent pathogens that cause acute, fatal disease is often hampered by development of microbial resistance to traditional chemotherapeutics. Further, most successful pathogens possess an array of immune evasion strategies to avoid detection and elimination by the host. Development of novel, immunomodulatory prophylaxes that target the host immune system, rather than the invading microbe, could serve as effective alternatives to traditional chemotherapies. Here we describe the development and mechanism of a novel pan-anti-bacterial prophylaxis. Using cationic liposome non-coding DNA complexes (CLDC) mixed with crude F. tularensis membrane protein fractions (MPF), we demonstrate control of virulent F. tularensis infection in vitro and in vivo. CLDC+MPF inhibited bacterial replication in primary human and murine macrophages in vitro. Control of infection in macrophages was mediated by both reactive nitrogen species (RNS) and reactive oxygen species (ROS) in mouse cells, and ROS in human cells. Importantly, mice treated with CLDC+MPF 3 days prior to challenge survived lethal intranasal infection with virulent F. tularensis. Similarly to in vitro observations, in vivo protection was dependent on the presence of RNS and ROS. Lastly, CLDC+MPF was also effective at controlling infections with Yersinia pestis, Burkholderia pseudomallei and Brucella abortus. Thus, CLDC+MPF represents a novel prophylaxis to protect against multiple, highly virulent pathogens

    Nasal Acai Polysaccharides Potentiate Innate Immunity to Protect against Pulmonary Francisella tularensis and Burkholderia pseudomallei Infections

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    Pulmonary Francisella tularensis and Burkholderia pseudomallei infections are highly lethal in untreated patients, and current antibiotic regimens are not always effective. Activating the innate immune system provides an alternative means of treating infection and can also complement antibiotic therapies. Several natural agonists were screened for their ability to enhance host resistance to infection, and polysaccharides derived from the Acai berry (Acai PS) were found to have potent abilities as an immunotherapeutic to treat F. tularensis and B. pseudomallei infections. In vitro, Acai PS impaired replication of Francisella in primary human macrophages co-cultured with autologous NK cells via augmentation of NK cell IFN-Ξ³. Furthermore, Acai PS administered nasally before or after infection protected mice against type A F. tularensis aerosol challenge with survival rates up to 80%, and protection was still observed, albeit reduced, when mice were treated two days post-infection. Nasal Acai PS administration augmented intracellular expression of IFN-Ξ³ by NK cells in the lungs of F. tularensis-infected mice, and neutralization of IFN-Ξ³ ablated the protective effect of Acai PS. Likewise, nasal Acai PS treatment conferred protection against pulmonary infection with B. pseudomallei strain 1026b. Acai PS dramatically reduced the replication of B. pseudomallei in the lung and blocked bacterial dissemination to the spleen and liver. Nasal administration of Acai PS enhanced IFN-Ξ³ responses by NK and Ξ³Ξ΄ T cells in the lungs, while neutralization of IFN-Ξ³ totally abrogated the protective effect of Acai PS against pulmonary B. pseudomallei infection. Collectively, these results demonstrate Acai PS is a potent innate immune agonist that can resolve F. tularensis and B. pseudomallei infections, suggesting this innate immune agonist has broad-spectrum activity against virulent intracellular pathogens

    Generation of a Convalescent Model of Virulent Francisella tularensis Infection for Assessment of Host Requirements for Survival of Tularemia

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    Francisella tularensis is a facultative intracellular bacterium and the causative agent of tularemia. Development of novel vaccines and therapeutics for tularemia has been hampered by the lack of understanding of which immune components are required to survive infection. Defining these requirements for protection against virulent F. tularensis, such as strain SchuS4, has been difficult since experimentally infected animals typically die within 5 days after exposure to as few as 10 bacteria. Such a short mean time to death typically precludes development, and therefore assessment, of immune responses directed against virulent F. tularensis. To enable identification of the components of the immune system that are required for survival of virulent F. tularensis, we developed a convalescent model of tularemia in C57Bl/6 mice using low dose antibiotic therapy in which the host immune response is ultimately responsible for clearance of the bacterium. Using this model we demonstrate Ξ±Ξ²TCR+ cells, Ξ³Ξ΄TCR+ cells, and B cells are necessary to survive primary SchuS4 infection. Analysis of mice deficient in specific soluble mediators shows that IL-12p40 and IL-12p35 are essential for survival of SchuS4 infection. We also show that IFN-Ξ³ is required for survival of SchuS4 infection since mice lacking IFN-Ξ³R succumb to disease during the course of antibiotic therapy. Finally, we found that both CD4+ and CD8+ cells are the primary producers of IFN-Ξ³and that Ξ³Ξ΄TCR+ cells and NK cells make a minimal contribution toward production of this cytokine throughout infection. Together these data provide a novel model that identifies key cells and cytokines required for survival or exacerbation of infection with virulent F. tularensis and provides evidence that this model will be a useful tool for better understanding the dynamics of tularemia infection

    Polyclonal mucosa-associated invariant T cells have unique innate functions in bacterial infection

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    Mucosa-associated invariant T (MAIT) cells are a unique population of αβ T cells in mammals that reside preferentially in mucosal tissues and express an invariant Vα paired with limited Vβ T-cell receptor (TCR) chains. Furthermore, MAIT cell development is dependent upon the expression of the evolutionarily conserved major histocompatibility complex (MHC) class Ib molecule MR1. Using in vitro assays, recent studies have shown that mouse and human MAIT cells are activated by antigen-presenting cells (APCs) infected with diverse microbes, including numerous bacterial strains and yeasts, but not viral pathogens. However, whether MAIT cells play an important, and perhaps unique, role in controlling microbial infection has remained unclear. To probe MAIT cell function, we show here that purified polyclonal MAIT cells potently inhibit intracellular bacterial growth of Mycobacterium bovis BCG in macrophages (MΦ) in coculture assays, and this inhibitory activity was dependent upon MAIT cell selection by MR1, secretion of gamma interferon (IFN-γ), and an innate interleukin 12 (IL-12) signal from infected MΦ. Surprisingly, however, the cognate recognition of MR1 by MAIT cells on the infected MΦ was found to play only a minor role in MAIT cell effector function. We also report that MAIT cell-deficient mice had higher bacterial loads at early times after infection compared to wild-type (WT) mice, demonstrating that MAIT cells play a unique role among innate lymphocytes in protective immunity against bacterial infection
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