1,537 research outputs found

    Differential Gene Expression Segregates Cattle Confirmed Positive for Bovine Tuberculosis from Antemortem Tuberculosis Test-False Positive Cattle Originating from Herds Free of Bovine Tuberculosis

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    Antemortem tests for bovine tuberculosis (bTB) currently used in the US measure cell-mediated immune responses against Mycobacterium bovis. Postmortem tests for bTB rely on observation of gross and histologic lesions of bTB, followed by bacterial isolation or molecular diagnostics. Cumulative data from the state of Michigan indicates that 98 to 99% of cattle that react positively in antemortem tests are not confirmed positive for bTB at postmortem examination. Understanding the fundamental differences in gene regulation between antemortem test-false positive cattle and cattle that have bTB may allow identification of molecular markers that can be exploited to better separate infected from noninfected cattle. An immunospecific cDNA microarray was used to identify altered gene expression (P ≤ 0.01) of 122 gene features between antemortem test-false positive cattle and bTB-infected cattle following a 4-hour stimulation of whole blood with tuberculin. Further analysis using quantitative real-time PCR assays validated altered expression of 8 genes that had differential power (adj  P ≤ 0.05) to segregate cattle confirmed positive for bovine tuberculosis from antemortem tuberculosis test-false positive cattle originating from herds free of bovine tuberculosis

    Crystal Structure of VapBC-1 from Nontypeable \u3ci\u3eHaemophilus influenzae\u3c/i\u3e and the Effect of Pin Domain Mutations on Survival During Infection

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    Toxin-antitoxin (TA) gene pairs have been identified in nearly all bacterial genomes sequenced to date and are thought to facilitate persistence and antibiotic tolerance. TA loci are classified into various types based upon the characteristics of their antitoxins, with those in type II expressing proteic antitoxins. Many toxins from type II modules are ribonucleases that maintain a PilT N-terminal (PIN) domain containing conserved amino acids considered essential for activity. The vapBC (virulence-associated protein) TA system is the largest subfamily in this class and has been linked to pathogenesis of nontypeable Haemophilus influenzae (NTHi). In this study, the crystal structure of the VapBC-1 complex from NTHi was determined to 2.20 Å resolution. Based on this structure, aspartate-to-asparagine and glutamate-to-glutamine mutations of four conserved residues in the PIN domain of the VapC-1 toxin were constructed and the effects of the mutations on protein-protein interactions, growth of Escherichia coli, and pathogenesis ex vivo were tested. Finally, a novel model system was designed and utilized that consists of an NTHi ΔvapBC-1 strain complemented in cis with the TA module containing a mutated or wild-type toxin at an ectopic site on the chromosome. This enabled the analysis of the effect of PIN domain toxin mutants in tandem with their wild-type antitoxin under the control of the vapBC-1 native promoter and in single copy. This is the first report of a system facilitating the study of TA mutant operons in the background of NTHi during infections of primary human tissues ex vivo

    From Sensors to Silencers: Quinoline- and Benzimidazole-Sulfonamides as Inhibitors for Zinc Proteases

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    Derived from the extensive work in the area of small molecule zinc(II) ion sensors, chelating fragment libraries of quinoline- and benzimidazole-sulfonamides have been prepared and screened against several different zinc(II)-dependent matrix metalloproteinases (MMPs). The fragments show impressive inhibition of these metalloenzymes and preferences for different MMPs based on the nature of the chelating group. The findings show that focused chelator libraries are a powerful strategy for the discovery of lead fragments for metalloprotein inhibition

    Beyond Hebb: Exclusive-OR and Biological Learning

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    A learning algorithm for multilayer neural networks based on biologically plausible mechanisms is studied. Motivated by findings in experimental neurobiology, we consider synaptic averaging in the induction of plasticity changes, which happen on a slower time scale than firing dynamics. This mechanism is shown to enable learning of the exclusive-OR (XOR) problem without the aid of error back-propagation, as well as to increase robustness of learning in the presence of noise.Comment: 4 pages RevTeX, 2 figures PostScript, revised versio

    Champ or chump? Challenge and threat states during pressurized competition

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    The present research examined the immediate impact of challenge and threat states on golf performance in both real competition and a laboratory-based task. In study 1, one hundred and ninety-nine experienced golfers reported their evaluations of competition demands and personal coping resources before a golf competition. Evaluating the competition as a challenge (i.e., sufficient resources to cope with demands) was associated with superior performance. In study 2, sixty experienced golfers randomly received challenge or threat manipulation instructions and then performed a competitive golf putting task. Challenge and threat states were successfully manipulated and the challenge group outperformed the threat group. Furthermore, the challenge group reported less anxiety, more facilitative interpretations of anxiety, less conscious processing, and displayed longer quiet eye durations. However, these variables failed to mediate the group-performance relationship. These studies demonstrate the importance of considering pre-performance psychophysiological states when examining the influence of competitive pressure on motor performance
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