241 research outputs found

    Formalin injection causes a coordinated spinal cord CO/NO-cGMP signaling system response

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    BACKGROUND: The CO/NO-cGMP signalling system participates in the regulation of many physiological processes. The roles this system plays in spinal cord nociceptive signalling are particularly important. While individual components have been examined in isolation, little study has been dedicated to understanding the regulation and functioning of the system as a whole. RESULTS: In these studies we examined the time course of expression of 13 genes coding for components of this system including isoforms of the heme oxygenase (HO), nitric oxide synthase (NOS), soluble guanylate cyclase (sGC), cGMP dependent protein kinase (PKG) and phosphodiesterase (PDE) enzyme systems. Of the 13 genes studied, 11 had spinal cord mRNA levels elevated at one or more time points up to 48 hours after hindpaw formalin injection. Of the 11 with elevated mRNA, 8 had elevated protein levels 48 hours after formalin injection when mechanical allodynia was maximal. No component had an increased protein level which did not have an increased mRNA level at one or more time points. Injection of morphine 10 mg/kg prior to formalin completely abolished the acute nociceptive behaviours, but did not alter the degree of sensitivity which developed in the formalin treated hind paws during the subsequent 48 hours. Morphine treatment did, however, eliminate formalin induced increases in enzyme protein levels. CONCLUSION: Our results indicate that the expression of the components of the CO/NO-cGMP signalling system seems to be coordinated in such a way that a generalized multi-level enhancement rather than a tightly limited step specific response occurs with noxious stimulation. Furthermore, the analgesic morphine administered prior to noxious stimulation can prevent long-term changes in gene expression though not necessarily nociceptive sensitisation

    Polymer thin film with in situ synthesized silver nanoparticles as a potent reusable bactericide

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    Silver nanoparticles are well-established antibacterial agents. However, an effective design and formulation that ensures: (i) ease of synthesis and fabrication, (ii) amenability to deployment over large surfaces of variable shape, (iii) high efficacy and (iv) multiple reuses with the possibility of periodic monitoring, is yet to emerge. A nanocomposite thin film of poly(vinyl alcohol) with silver nanoparticles generated within, through a soft-chemical in situ synthesis, is shown to be a good candidate to fulfil most of the above requirements. Efficient antibacterial activity, multiple reuses and facile monitoring of the film through spectroscopy and microscopy are demonstrated. Preliminary studies demonstrate the effective bactericidal action of the thin film coating on stirring rods

    Ergodic encoding for single-element ultrasound imaging in vivo

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    Conventional ultrasound imaging relies on the computation of geometric time delay from multiple sensors to detect the position of a scatterer. In this paper, we present Ergodic Relay Ultrasound Imaging (ERUI), a method that utilizes an ergodic cavity down to a single ultrasonic sensor for ultrasound imaging. With the proposed method, the ergodic cavity creates a unique temporal signature that encodes the position of a scatterer. When compared to standard approaches, ERUI enables the generation of images of comparable quality while utilizing fewer detector elements. Our results suggest that ERUI has the potential to achieve image resolution similar to that of traditional imaging techniques, shifting the complexity from hardware to sofware. The demonstrated feasibility offers a promising path towards ultrasound probes with reduced costs and complexity for more portable scanning devices.Comment: 5 pages, 4 figures, Lette

    Séparation de mélanges par ondelettes et réseaux de neurones : étude comparée

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    - Ces travaux se situent dans le cadre d'un projet qui a pour ambition la conception d'un système ambulatoire longue durée multi-varié pour la surveillance de malaises inexpliqués et de troubles du sommeil. Plus précisément, ces objectifs concernent l'étude de la localisation spatiale optimale de nouveaux capteurs et l'extraction, à partir d'enregistrements de sommeil réels, des signaux nécessaires aux diagnostics. D'un point de vue traitement du signal, ce problème de l'extraction des signaux est assimilé à la séparation de mélanges et deux approches sont proposées : une décomposition suivant une base d'ondelettes orthonormées et des réseaux de neurones. Les deux méthodes utilisées fournissent des résultats acceptables avec des performances équivalentes, et meilleures qu'avec un filtrage traditionnel. Le réseau de neurones permet d'extraire la fonction de transfert non linéaire entre deux dérivations d'EEG, mais sa mise en oeuvre est délicate. La méthode basée sur les ondelettes permet d'extraire deux signaux à partir d'une seule dérivation avec une grande simplicité de mise en oeuvre

    Assessment of the stability of morphological ECG features and their potential for person verification/identification

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    This study investigates the potential of a set of ECG morphological features for person verification/identification. The measurements are done over 145 pairs of ECG recordings from healthy subjects, acquired 5 years apart (T1, T2 = T1+5 years). Time, amplitude, area and slope descriptors of the QRS-T pattern are analysed in 4 ECG leads, forming quasi-orthogonal lead system (II&III, V1, V5). The correspondence between feature values in T1 and T2 is verified via factor analysis by principal components extraction method; correlation analysis applied over the measurements in T1 and T2; synthesis of regression equations for prediction of features’ values in T2 based on T1 measurements; and cluster analysis for assessment of the correspondence between measured and predicted feature values. Thus, 11 amplitude descriptors of the QRS complex are highlighted as stable, i.e. keeping their strong correlation (≥0.7) within a certain factor, weak correlation (<0.3) with the features from the remaining factors and presenting high correlation in the two measurement periods that is a sign for their person verification/identification potential. The observed coincidence between feature values measured in T2 and predicted via the designed regression models (r=0.93) suggests about the confidence of person identification via the proposed morphological features

    PageMan: An interactive ontology tool to generate, display, and annotate overview graphs for profiling experiments

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    BACKGROUND: Microarray technology has become a widely accepted and standardized tool in biology. The first microarray data analysis programs were developed to support pair-wise comparison. However, as microarray experiments have become more routine, large scale experiments have become more common, which investigate multiple time points or sets of mutants or transgenics. To extract biological information from such high-throughput expression data, it is necessary to develop efficient analytical platforms, which combine manually curated gene ontologies with efficient visualization and navigation tools. Currently, most tools focus on a few limited biological aspects, rather than offering a holistic, integrated analysis. RESULTS: Here we introduce PageMan, a multiplatform, user-friendly, and stand-alone software tool that annotates, investigates, and condenses high-throughput microarray data in the context of functional ontologies. It includes a GUI tool to transform different ontologies into a suitable format, enabling the user to compare and choose between different ontologies. It is equipped with several statistical modules for data analysis, including over-representation analysis and Wilcoxon statistical testing. Results are exported in a graphical format for direct use, or for further editing in graphics programs. PageMan provides a fast overview of single treatments, allows genome-level responses to be compared across several microarray experiments covering, for example, stress responses at multiple time points. This aids in searching for trait-specific changes in pathways using mutants or transgenics, analyzing development time-courses, and comparison between species. In a case study, we analyze the results of publicly available microarrays of multiple cold stress experiments using PageMan, and compare the results to a previously published meta-analysis. PageMan offers a complete user's guide, a web-based over-representation analysis as well as a tutorial, and is freely available at . CONCLUSION: PageMan allows multiple microarray experiments to be efficiently condensed into a single page graphical display. The flexible interface allows data to be quickly and easily visualized, facilitating comparisons within experiments and to published experiments, thus enabling researchers to gain a rapid overview of the biological responses in the experiments

    Human Gene Coexpression Landscape: Confident Network Derived from Tissue Transcriptomic Profiles

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    This is an open-access article distributed under the terms of the Creative Commons Attribution License.[Background]: Analysis of gene expression data using genome-wide microarrays is a technique often used in genomic studies to find coexpression patterns and locate groups of co-transcribed genes. However, most studies done at global >omic> scale are not focused on human samples and when they correspond to human very often include heterogeneous datasets, mixing normal with disease-altered samples. Moreover, the technical noise present in genome-wide expression microarrays is another well reported problem that many times is not addressed with robust statistical methods, and the estimation of errors in the data is not provided. [Methodology/Principal Findings]: Human genome-wide expression data from a controlled set of normal-healthy tissues is used to build a confident human gene coexpression network avoiding both pathological and technical noise. To achieve this we describe a new method that combines several statistical and computational strategies: robust normalization and expression signal calculation; correlation coefficients obtained by parametric and non-parametric methods; random cross-validations; and estimation of the statistical accuracy and coverage of the data. All these methods provide a series of coexpression datasets where the level of error is measured and can be tuned. To define the errors, the rates of true positives are calculated by assignment to biological pathways. The results provide a confident human gene coexpression network that includes 3327 gene-nodes and 15841 coexpression-links and a comparative analysis shows good improvement over previously published datasets. Further functional analysis of a subset core network, validated by two independent methods, shows coherent biological modules that share common transcription factors. The network reveals a map of coexpression clusters organized in well defined functional constellations. Two major regions in this network correspond to genes involved in nuclear and mitochondrial metabolism and investigations on their functional assignment indicate that more than 60% are house-keeping and essential genes. The network displays new non-described gene associations and it allows the placement in a functional context of some unknown non-assigned genes based on their interactions with known gene families. [Conclusions/Significance]: The identification of stable and reliable human gene to gene coexpression networks is essential to unravel the interactions and functional correlations between human genes at an omic scale. This work contributes to this aim, and we are making available for the scientific community the validated human gene coexpression networks obtained, to allow further analyses on the network or on some specific gene associations. The data are available free online at http://bioinfow.dep.usal.es/coexpression/. © 2008 Prieto et al.Funding and grant support was provided by the Ministery of Health, Spanish Government (ISCiii-FIS, MSyC; Project reference PI061153) and by the Ministery of Education, Castilla-Leon Local Government (JCyL; Project reference CSI03A06).Peer Reviewe
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