229 research outputs found

    Exercise reduces activation of microglia isolated from hippocampus and brain of aged mice

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    Background: Aging is associated with low-grade neuroinflammation that includes basal increases in proinflammatory cytokines and expression of inflammatory markers on microglia. Exercise can reduce neuroinflammation following infection in aged animals, but whether exercise modulates basal changes in microglia activation is unknown. Therefore, we evaluated changes in basal microglia activation in cells isolated from the hippocampus and remaining brain following running-wheel access. Methods: Adult (4 months) and aged (22 months) male and female BALB/c mice were housed with or without running wheels for 10 weeks. Microglia were isolated from the hippocampus or remaining brain. Flow cytometry was used to determine microglia (CD11b+ and CD45low) that co-labeled with CD86, CD206, and MHC II. Results: Aged mice showed a greater proportion of CD86 and MHC II positive microglia. In aged females, access to a running wheel decreased proportion of CD86+ and MHC II+ microglia in the hippocampus whereas aged males in the running group showed a decrease in the proportion of CD86+ microglia in the brain and an increase in the proportion of MHC II+ microglia in hippocampus and brain. Conclusion: Overall, these data indicate that running-wheel access modulates microglia activation, but these effects vary by age, sex, and brain region

    Does mind wandering create a mental context change that facilitates memory retrieval?

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    This study tested whether task-unrelated thoughts (TUTs) can benefit memory retrieval by inducing mental context changes in the presence of output interference. Specifically, Study 1 examined the effects of an incubation period on recall in a long-duration verbal fluency task (recalling animal names). Study 2 replicated Study 1, but with longer task times. Both studies also assessed whether TUT rates during an incubation period predict post-incubation recall output, as would be expected if TUTs create mental context changes that reduce output interference between recall periods. Study 1 tested 204 participants, and Study 2 tested 211, and both presented a recalling-animals verbal fluency task and an incubation-period reading task with embedded thought probes to assess TUTs. In Study 1, participants recalled animals for 7 min pre-incubation and 2 min post-incubation, whereas in Study 2, participants recalled animal names for 9 minutes pre-incubation, and incubation-task duration increased from 11 to 12.5 min. Neither experiment showed the predicted incubation effects, nor a correlation between TUT rates and post-incubation fluency; only Study 2 showed a short-lived incubation effect in an exploratory analysis

    "Women's rights, the European Court and Supranational Constitutionalism"

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    This analysis examines supranational constitutionalism in the European Union. In particular, the study focuses on the role of the European Court of Justice in the creation of women’s rights. I examine the interaction between the Court and member state governments in legal integration, and also the integral role that women’s advocates – both individual activists and groups – have played in the development of EU social provisions. The findings suggest that this litigation dynamic can have the effect of fueling the integration process by creating new rights that may empower social actors and EU organizations, with the ultimate effect of diminishing member state government control over the scope and direction of EU law. This study focuses specifically on gender equality law, yet provides a general framework for examining the case law in subsequent legal domains, with the purpose of providing a more nuanced understanding of supranational governance and constitutionalism

    Effect of smoking on physical and cognitive capability in later life: a multicohort study using observational and genetic approaches

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    Objectives: The observed associations between smoking and functional measures at older ages are vulnerable to bias and confounding. Mendelian randomisation (MR) uses genotype as an instrumental variable to estimate unconfounded causal associations. We conducted a meta-analysis of the observational associations and implemented an MR approach using the smoking-related single nucleotide polymorphism rs16969968 to explore their causal nature. Setting: 9 British cohorts belonging to the HALCyon collaboration. Participants: Individual participant data on N=26 692 individuals of European ancestry (N from earliest phase analysed per study) of mean ages 50-79 years were available for inclusion in observational meta-analyses of the primary outcomes. Primary outcomes: Physical capability, cognitive capability and cognitive decline. The smoking exposures were cigarettes per day, current versus ex-smoker, current versus never smoker and ever versus never smoker. Results: In observational analyses current and ever smoking were generally associated with poorer physical and cognitive capability. For example, current smokers had a general fluid cognition score which was 0.17 z-score units (95% CI -0.221 to -0.124) lower than ex-smokers in cross-sectional analyses. Current smokers had a walk speed which was 0.25 z-score units lower than never smokers (95% CI -0.338 to -0.170). An MR instrumental variable approach for current versus ex-smoker and number of cigarettes smoked per day produced CIs which neither confirmed nor refuted the observational estimates. The number of genetic associations stratified by smoking status were consistent with type I error. Conclusions: Our observational analysis supports the hypothesis that smoking is detrimental to physical and cognitive capability. Further studies are needed for a suitably powered MR approach

    The Sodium Sialic Acid Symporter From Staphylococcus aureus Has Altered Substrate Specificity

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    Mammalian cell surfaces are decorated with complex glycoconjugates that terminate with negatively charged sialic acids. Commensal and pathogenic bacteria can use host-derived sialic acids for a competitive advantage, but require a functional sialic acid transporter to import the sugar into the cell. This work investigates the sodium sialic acid symporter (SiaT) from Staphylococcus aureus (SaSiaT). We demonstrate that SaSiaT rescues an Escherichia coli strain lacking its endogenous sialic acid transporter when grown on the sialic acids N-acetylneuraminic acid (Neu5Ac) or N-glycolylneuraminic acid (Neu5Gc). We then develop an expression, purification and detergent solubilization system for SaSiaT and demonstrate that the protein is largely monodisperse in solution with a stable monomeric oligomeric state. Binding studies reveal that SaSiaT has a higher affinity for Neu5Gc over Neu5Ac, which was unexpected and is not seen in another SiaT homolog. We develop a homology model and use comparative sequence analyses to identify substitutions in the substrate-binding site of SaSiaT that may explain the altered specificity. SaSiaT is shown to be electrogenic, and transport is dependent upon more than one Na+ ion for every sialic acid molecule. A functional sialic acid transporter is essential for the uptake and utilization of sialic acid in a range of pathogenic bacteria, and developing new inhibitors that target these transporters is a valid mechanism for inhibiting bacterial growth. By demonstrating a route to functional recombinant SaSiaT, and developing the in vivo and in vitro assay systems, our work underpins the design of inhibitors to this transporter

    'If You Desire to Enjoy Life, Avoid Unpunctual People': Women, Timetabling and Domestic Advice, 1850–1910

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    In the second half of the nineteenth century domestic advice manuals applied the language of modern, public time management to the private sphere. This article uses domestic advice and cookery books, including Isabella Beeton's Book of Household Management, to argue that women in the home operated within multiple, overlapping temporalities that incorporated daily, annual, linear and cyclical scales. I examine how seasonal and annual timescales coexisted with the ticking clock of daily time as a framework within which women were instructed to organize their lives in order to conclude that the increasing concern of advice writers with matters of timekeeping and punctuality towards the end of the nineteenth century indicates not the triumph of 'clock time' but rather its failure to overturn other ways of thinking about and using time

    The basis for non-canonical ROK family function in the N-acetylmannosamine kinase from the pathogen Staphylococcus aureus

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    In environments where glucose is limited, some pathogenic bacteria metabolize host-derived sialic acid as a nutrient source. N-Acetylmannosamine kinase (NanK) is the second enzyme of the bacterial sialic acid import and degradation pathway and adds phosphate to N-acetylmannosamine using ATP to prime the molecule for future pathway reactions. Sequence alignments reveal that Gram-positive NanK enzymes belong to the Repressor, ORF, Kinase (ROK) family, but many lack the canonical Zn-binding motif expected for this function, and the sugar-binding EXGH motif is altered to EXGY. As a result, it is unclear how they perform this important reaction. Here, we study the Staphylococcus aureus NanK (SaNanK), which is the first characterization of a Gram-positive NanK. We report the kinetic activity of SaNanK along with the ligand-free, N-acetylmannosamine-bound and substrate analog GlcNAc-bound crystal structures (2.33, 2.20, and 2.20 Ã… resolution, respectively). These demonstrate, in combination with small-angle X-ray scattering, that SaNanK is a dimer that adopts a closed conformation upon substrate binding. Analysis of the EXGY motif reveals that the tyrosine binds to the N-acetyl group to select for the "boat" conformation of N-acetylmannosamine. Moreover, SaNanK has a stacked arginine pair coordinated by negative residues critical for thermal stability and catalysis. These combined elements serve to constrain the active site and orient the substrate in lieu of Zn binding, representing a significant departure from canonical NanK binding. This characterization provides insight into differences in the ROK family and highlights a novel area for antimicrobial discovery to fight Gram-positive and S. aureus infections
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