699 research outputs found

    The ectodomain of Toll-like receptor 9 is cleaved to generate a functional receptor.

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    Mammalian Toll-like receptors (TLRs) 3, 7, 8 and 9 initiate immune responses to infection by recognizing microbial nucleic acids; however, these responses come at the cost of potential autoimmunity owing to inappropriate recognition of self nucleic acids. The localization of TLR9 and TLR7 to intracellular compartments seems to have a role in facilitating responses to viral nucleic acids while maintaining tolerance to self nucleic acids, yet the cell biology regulating the transport and localization of these receptors remains poorly understood. Here we define the route by which TLR9 and TLR7 exit the endoplasmic reticulum and travel to endolysosomes in mouse macrophages and dendritic cells. The ectodomains of TLR9 and TLR7 are cleaved in the endolysosome, such that no full-length protein is detectable in the compartment where ligand is recognized. Notably, although both the full-length and cleaved forms of TLR9 are capable of binding ligand, only the processed form recruits MyD88 on activation, indicating that this truncated receptor, rather than the full-length form, is functional. Furthermore, conditions that prevent receptor proteolysis, including forced TLR9 surface localization, render the receptor non-functional. We propose that ectodomain cleavage represents a strategy to restrict receptor activation to endolysosomal compartments and prevent TLRs from responding to self nucleic acids

    Enantioselective Total Synthesis of (+)-Psiguadial B

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    The first enantioselective total synthesis of the cytotoxic natural product (+)-psiguadial B is reported. Key features of the synthesis include (1) the enantioselective preparation of a key cyclobutane intermediate by a tandem Wolff rearrangement/asymmetric ketene addition, (2) a directed C(sp^3)–H alkenylation reaction to strategically forge the C1–C2 bond, and (3) a ring-closing metathesis to build the bridging bicyclo[4.3.1]decane terpene framework

    Professional Development as a Process of Cultural Brokering: Positioning Coaches as Cultural Brokers

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    Teachers who serve diverse students must navigate two “worlds.” One world is that of standardized curricula and pedagogy and the other is culturally relevant education. To effectively navigate these worlds, teachers need assistance from “cultural brokers” who can help make sense of the tension that emerges when these two educational worlds interact. This study analyzes the work of two Center for Research on Education, Diversity, and Excellence coaches who worked as cultural brokers to help teachers integrate multiple pedagogical models. The results indicate the coaches shifted their strategies depending on teacher preferences, and helped teachers overcome constraints within their classrooms and curricula. Framing coaches as “cultural brokers” may be a useful metaphor for others assisting teachers with navigating the tension that emerges in implementing culturally relevant education

    A modular approach to prepare enantioenriched cyclobutanes: synthesis of (+)-rumphellaone A

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    A modular synthesis of enantioenriched polyfunctionalized cyclobutanes was developed that features an 8-aminoquinolinamide directed C–H arylation reaction. The C–H arylation products were derivatized through subsequent decarboxylative coupling processes. This synthetic strategy enabled a 9-step enantioselective total synthesis of the antiproliferative meroterpenoid (+)-rumphellaone A

    Longitudinal study of Asian elephants, Elephas maximus, indicates intermittent shedding of elephant endotheliotropic herpesvirus 1 during pregnancy

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    Introduction: EEHV-1 is a viral infection of elephants that has been associated with a fatal haemorrhagic syndrome in Asian elephants. Previous studies have suggested that pregnant animals may shed more virus than non-pregnant animals. Methods: This study examined whether pregnancy affected the frequency or magnitude of shedding of elephant endotheliotropic herpesvirus 1 (EEHV1) using Taq man real-time PCR on trunk washes from four female elephants from a UK collection over three time periods between 2011 and 2014. These periods included pregnancies in two animals (period 1 and period 3). Behavioural observations made by keepers were also assessed. Results: During period 1 there was a high degree of social hierarchical instability which led to a hierarchy change, and was associated with aggressive behaviour. Also during period 1 EEHV-1 shedding was of a higher magnitude and frequency than in the latter two time periods. Conclusions: These results suggest that there is no clear relationship between shedding and pregnancy, and that behavioural stressors may be related to an increase in EEHV-1 shedding

    Beliefs about pharmaceutical medicines and natural remedies explain individual variation in placebo analgesia

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    This study examined whether placebo responses were predicted by a theoretical model of specific and general treatment beliefs. Using a randomised cross-over, experimental design (168 healthy individuals) we assessed whether responses to a cold pressor task were influenced by two placebo creams described as Pharmaceutical vs Natural origin. We assessed whether placebo responses were predicted by pre-treatment beliefs about the treatments (placebo) and by beliefs about the pain. The efficacy of both Pharmaceutical and Natural Placebos in reducing Pain Intensity was predicted by aspects of pain catastrophizing including Feelings of Helplessness (Pharmaceutical: B=0.03, p<0.01, Natural: B=0.02, p<0.05) and Magnification of Pain (Pharmaceutical: B=0.04, p<0.05, Natural: B=0.05, p<0.05) but also by pre-treatment Necessity beliefs (Pharmaceutical: B=0.21, p<0.01, Natural: B=0.16, p<0.05) and, for the Pharmaceutical condition, by more general beliefs in personal sensitivity to pharmaceuticals (B=0.14, p<0.05). Treatment Necessity beliefs also partially mediated the effects of Helplessness on placebo responses. Treatment Necessity beliefs for the Pharmaceutical Placebo were influenced by general pharmaceutical beliefs whereas Necessity beliefs for the Natural Placebo were informed by general background beliefs about holistic treatments. Our findings demonstrate that treatment beliefs influence the placebo effect suggesting that they may offer an additional approach for understanding the placebo effect. PERSPECTIVE: Placebo effects contribute to responses to active analgesics. Understanding how beliefs about different types of medicines influence placebo analgesia may be useful in understanding variations in treatment response. Using the cold-pressor paradigm we found that placebo analgesia is influenced by beliefs about natural remedies, pharmaceutical medicines and about pain

    The catabolite repressor protein-cyclic AMP complex regulates csgD and biofilm formation in uropathogenic Escherichia coli

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    The extracellular matrix protects Escherichia coli from immune cells, oxidative stress, predation, and other environmental stresses. Production of the E. coli extracellular matrix is regulated by transcription factors that are tuned to environmental conditions. The biofilm master regulator protein CsgD upregulates curli and cellulose, the two major polymers in the extracellular matrix of uropathogenic E. coli (UPEC) biofilms. We found that cyclic AMP (cAMP) regulates curli, cellulose, and UPEC biofilms through csgD. The alarmone cAMP is produced by adenylate cyclase (CyaA), and deletion of cyaA resulted in reduced extracellular matrix production and biofilm formation. The catabolite repressor protein (CRP) positively regulated csgD transcription, leading to curli and cellulose production in the UPEC isolate, UTI89. Glucose, a known inhibitor of CyaA activity, blocked extracellular matrix formation when added to the growth medium. The mutant strains ΔcyaA and Δcrp did not produce rugose biofilms, pellicles, curli, cellulose, or CsgD. Three putative CRP binding sites were identified within the csgD-csgB intergenic region, and purified CRP could gel shift the csgD-csgB intergenic region. Additionally, we found that CRP binded upstream of kpsMT, which encodes machinery for K1 capsule production. Together our work shows that cAMP and CRP influence E. coli biofilms through transcriptional regulation of csgD. IMPORTANCE The catabolite repressor protein (CRP)-cyclic AMP (cAMP) complex influences the transcription of ∌7% of genes on the Escherichia coli chromosome (D. Zheng, C. Constantinidou, J. L. Hobman, and S. D. Minchin, Nucleic Acids Res 32:5874–5893, 2004, https://dx.doi.org/10.1093/nar/gkh908). Glucose inhibits E. coli biofilm formation, and ΔcyaA and Δcrp mutants show impaired biofilm formation (D. W. Jackson, J.W. Simecka, and T. Romeo, J Bacteriol 184:3406–3410, 2002, https://dx.doi.org/10.1128/JB.184.12.3406-3410.2002). We determined that the cAMP-CRP complex regulates curli and cellulose production and the formation of rugose and pellicle biofilms through csgD. Additionally, we propose that cAMP may work as a signaling compound for uropathogenic E. coli (UPEC) to transition from the bladder lumen to inside epithelial cells for intracellular bacterial community formation through K1 capsule regulation

    Peripheral blood leukocyte response and macrophage function during Eimeria adenoeides infection in turkey poults

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    Intestinal coccidiosis, caused by various species of Eimeria, is an economically important disease of chickens and turkeys. The peripheral blood leukocyte response and macrophage functions during a coccidial infection in turkeys have not been defined. To examine these aspects of innate immunity during primary Eimeria infection in turkeys, 4-week-old poults were orally inoculated with either 50,000 E. adenoeides oocyst (24 infected poults) or water (24 control poults). To monitor the concentrations and proportions of white blood cells (WBC) throughout the course of infection, heparinized blood was collected from 12 infected and 12 control poults prior to inoculation (day 0), and on days 4, 7, and 11 post-inoculation (PI). To study macrophage function, Sephadex-elicited abdominal exudate cells (macrophages) were collected on day 7 PI from 12 infected and 12 control poults. Macrophages were used to study phagocytosis of unopsonized and antibody-opsonized sheep red blood cells (SRBC), production of nitric oxide, and production of cytotoxic factors. E. adenoeides infection was associated with alterations in the concentration of WBC, including a decrease in the numbers of circulating lymphocytes on day 4 and a rise in lymphocytes and heterophils on day 11. Although phagocytic activity was not different in macrophages from infected and control poults, macrophages from infected poults exhibited greater cytotoxic activity. Data from these studies strongly suggest that components of innate immunity were recruited and activated during this primary infection of turkey poults with E. adenoeides. Further investigations are needed to determine the role of these components in limiting primary infection by E. adenoeides
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