286 research outputs found

    A robot hand testbed designed for enhancing embodiment and functional neurorehabilitation of body schema in subjects with upper limb impairment or loss.

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    Many upper limb amputees experience an incessant, post-amputation "phantom limb pain" and report that their missing limbs feel paralyzed in an uncomfortable posture. One hypothesis is that efferent commands no longer generate expected afferent signals, such as proprioceptive feedback from changes in limb configuration, and that the mismatch of motor commands and visual feedback is interpreted as pain. Non-invasive therapeutic techniques for treating phantom limb pain, such as mirror visual feedback (MVF), rely on visualizations of postural changes. Advances in neural interfaces for artificial sensory feedback now make it possible to combine MVF with a high-tech "rubber hand" illusion, in which subjects develop a sense of embodiment with a fake hand when subjected to congruent visual and somatosensory feedback. We discuss clinical benefits that could arise from the confluence of known concepts such as MVF and the rubber hand illusion, and new technologies such as neural interfaces for sensory feedback and highly sensorized robot hand testbeds, such as the "BairClaw" presented here. Our multi-articulating, anthropomorphic robot testbed can be used to study proprioceptive and tactile sensory stimuli during physical finger-object interactions. Conceived for artificial grasp, manipulation, and haptic exploration, the BairClaw could also be used for future studies on the neurorehabilitation of somatosensory disorders due to upper limb impairment or loss. A remote actuation system enables the modular control of tendon-driven hands. The artificial proprioception system enables direct measurement of joint angles and tendon tensions while temperature, vibration, and skin deformation are provided by a multimodal tactile sensor. The provision of multimodal sensory feedback that is spatiotemporally consistent with commanded actions could lead to benefits such as reduced phantom limb pain, and increased prosthesis use due to improved functionality and reduced cognitive burden

    Espectros integrados EFOSC2/NTT de 10 cúmulos estelares pertenecientes a las Nubes de Magallanes

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    We present integrated spectra in the optical range for 10 concentrated Magellanic Clouds’ (MCs) stellar clusters, six of them belonging to the Large Magellanic Cloud, and the other four to the Small Magellanic Cloud. The spectra were obtained with the EFOSC2 spectrograph (NTT-ESO, La Silla, Chile). We estimate simultaneously age and foreground reddening by comparing the continuum distribution and line strengths of the cluster spectra with those of template spectra. The present cluster sample complements previous ones, in an effort to create a spectral library for the MCs with several clusters per age bin.Se presentan espectros integrados en el rango optico obtenidos con el espectrografo EFOSC2 (NTT-ESO, La Silla, Chile) de 6 cumulos estelares (CEs) de la Nube Mayor de Magallanes (NMM) y 4 de la Nube Menor (NmM). Las edades y enrojecimientos se determinaron comparando la distribucion del continuo y la intensidad de lıneas espectrales con estas mismas caracterısticas en espectros patrones (templates). Los 10 cumulos estudiados abarcan un amplio rango de edad y estan levemente enrojecidos. Estos espectros seran de gran utilidad para actualizar las bases de templates actualmente existentes para la metalicidad tıpicamente subsolar de las Nubes de Magallanes (NMs).Fil: Ahumada, Andrea Veronica. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; ArgentinaFil: Benítez Llambay, Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Astronomia Teórica y Experimental. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Instituto de Astronomia Teórica y Experimental; ArgentinaFil: Santos, J. F. C.. Universidade Federal do Minas Gerais; BrasilFil: Claria Olmedo, Juan Jose. Universidad Nacional de Cordoba. Observatorio Astronomico de Cordoba; ArgentinaFil: Bica, E.. Universidade Federal do Rio Grande do Sul; BrasilFil: Piatti, Andres Eduardo. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; Argentin

    Pk/pd of morphine for postoperative analgesia after coronary artery bypass grafting : Intrathecal morphine significantly reduces drug consumption

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    The aim of the present study was to evaluate intrathecal morphine outcome on postoperative pain and apply pharmacokinetic/pharmacodynamic model to justify morphine consumption, plasma concentration and pain intensity during coronary artery bypass grafting surgery. Thirty six patients were prospectively randomized for general anesthesia and allocated in the control or morphine (400 μg intrathecal) group. At postoperative period, all patients received a loading dose of morphine (1 mg bolus), and then patient-controlled analgesia device was installed and delivered until 36 h. Blood samples was collected from venous catheter, morphine plasma concentrations were determined by liquid chromatography and pain intensity evaluated by visual analogue scale. Drug dose requirements and pain intensity at rest were different between groups. No kinetic parameters difference was obtained. Maximum effect model and hysteresis curve were proposed to correlate drug plasma concentration versus time, drug consumption and pain intensity. Intrathecal morphine reduces at rest morphine consumption and pain intensity postoperatively; the best fit pharmacokinetic/pharmacodynamic models were maximum effect and hysteresis curveColegio de Farmacéuticos de la Provincia de Buenos Aire

    Strain Effects on the Oxidation of CO and HCOOH at Au-Pd Core-Shell Nanoparticles

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    The mechanism of CO and HCOOH electrooxidation in an acidic solution on carbon-supported Au–Pd core–shell nanoparticles was investigated by differential electrochemical mass spectrometry and in situ Fourier transform infrared (FTIR) spectroscopy. Analysis performed in nanostructures with 1.3 ± 0.1 nm (CS1) and 9.9 ± 1.1 nm (CS10) Pd shells provides compelling evidence that the mechanism of adsorbed CO (COads) oxidation is affected by structural and electronic effects introduced by the Au cores. In the case of CS10, a band associated with adsorbed OH species (OHads) is observed in the potential range of CO oxidation. This feature is not detected in the case of CS1, suggesting that the reaction follows an alternative mechanism involving COOHads species. The faradaic charge associated with COads oxidation as well as the Stark slope measured from FTIR indicates that the overall affinity and orbital coupling of CO to Pd are weaker for CS1 shells. FTIR spectroscopy also revealed the presence of HCOOads intermediate species only in the case of CS1. This observation allowed us to conclude that the higher activity of CS10 toward this reaction is due to a fast HCOOads oxidation step, probably involving OHads, to generate CO2. Density functional theory calculations are used to estimate the contributions of the so-called ligand and strain effects on the local density of states of the Pd d-band. The calculations strongly suggest that the key parameter contributing to the change in mechanism is the effective lattice strain

    treatment effect of alirocumab according to age group smoking status and hypertension pooled analysis from 10 randomized odyssey studies

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    Background Age, smoking, hypercholesterolemia, and hypertension are major risk factors for atherosclerotic cardiovascular disease. Objective We examined whether the effects of alirocumab on low-density lipoprotein cholesterol (LDL-C) differed according to age, hypertension, or smoking status. Methods Data were pooled from 10 Phase 3 ODYSSEY randomized trials (24–104 weeks' duration) in 4983 people with heterozygous familial hypercholesterolemia (FH) or non–familial hypercholesterolemia (3188 on alirocumab, 1795 on control [620 on ezetimibe and 1175 on placebo]). Most participants received concomitant maximum tolerated statin therapy. In 8 trials, the alirocumab dose was increased from 75 mg every 2 weeks (Q2W) to 150 mg Q2W at Week 12 if predefined risk-based LDL-C goals were not achieved at Week 8 (≥70 mg/dL in very high cardiovascular risk; ≥100 mg/dL in moderate or high cardiovascular risk). Two trials compared alirocumab 150 mg Q2W vs placebo. The efficacy and safety of alirocumab were assessed post hoc in subgroups stratified by age ( Results Alirocumab reduced LDL-C by 23.7% (75/150 mg vs ezetimibe + statin) to 65.4% (150 mg vs placebo + statin) from baseline to Week 24 vs control. Subgroup analyses confirmed no significant interactions in response to alirocumab between age group, hypertension, or smoking status. Overall rates of treatment-emergent adverse events were similar between alirocumab and control groups. Conclusions In this pooled analysis from 10 trials, alirocumab led to substantial LDL-C reductions vs control in every age group and regardless of hypertension or smoking status. Alirocumab was well tolerated in all subgroups

    A cell topography-based mechanism for ligand discrimination by the T cell receptor.

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    The T cell receptor (TCR) initiates the elimination of pathogens and tumors by T cells. To avoid damage to the host, the receptor must be capable of discriminating between wild-type and mutated self and nonself peptide ligands presented by host cells. Exactly how the TCR does this is unknown. In resting T cells, the TCR is largely unphosphorylated due to the dominance of phosphatases over the kinases expressed at the cell surface. However, when agonist peptides are presented to the TCR by major histocompatibility complex proteins expressed by antigen-presenting cells (APCs), very fast receptor triggering, i.e., TCR phosphorylation, occurs. Recent work suggests that this depends on the local exclusion of the phosphatases from regions of contact of the T cells with the APCs. Here, we developed and tested a quantitative treatment of receptor triggering reliant only on TCR dwell time in phosphatase-depleted cell contacts constrained in area by cell topography. Using the model and experimentally derived parameters, we found that ligand discrimination likely depends crucially on individual contacts being ∼200 nm in radius, matching the dimensions of the surface protrusions used by T cells to interrogate their targets. The model not only correctly predicted the relative signaling potencies of known agonists and nonagonists but also achieved this in the absence of kinetic proofreading. Our work provides a simple, quantitative, and predictive molecular framework for understanding why TCR triggering is so selective and fast and reveals that, for some receptors, cell topography likely influences signaling outcomes.This work was funded by The Wellcome Trust, the UK Medical Research Council, the UK Biotechnology and Biological Sciences Research Council and Cancer Research UK. We thank the Wolfson Imaging Centre, University of Oxford, for access to their microscope facility. We would like to thank the Wellcome Trust for the Sir Henry Dale Fellowship of R.A.F. (WT101609MA), the Royal Society for the University Research Fellowship of S.F.L. (UF120277) and acknowledge a GSK Professorship (D.K.). We are also grateful to Doug Tischer (UCSF, US) and Muaz Rushdi (Georgia Tech, US) for their critical comments on the manuscript

    The remarkably low affinity of CD4/peptide-major histocompatibility complex class II protein interactions

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    The αβ T-cell co-receptor CD4 enhances immune responses more than one million-fold in some assays, and yet the affinity of CD4 for its ligand, peptide-major histocompatibility class II (pMHC II) on antigen-presenting cells, is so weak that it was previously unquantifiable. Here, we report that a soluble form of CD4 failed to bind detectably to pMHC II in surface plasmon resonance-based assays, establishing a new upper limit for the solution affinity at 2.5 mM. However, when presented multivalently on magnetic beads, soluble CD4 bound pMHC II-expressing B cells, confirming that it is active and allowing mapping of the native co-receptor binding site on pMHC II. Whereas binding was undetectable in solution, the affinity of the CD4/pMHC II interaction could be measured in two dimensions (2D) using CD4- and adhesion molecule-functionalized, supported lipid bilayers, yielding a 2D dissociation constant, Kd, of ~5000 molecules/μm2. This value is 2-3 orders of magnitude higher than previously measured 2D Kd values for interacting leukocyte surface proteins. Calculations indicated, however, that CD4/pMHC II binding would increase rates of T-cell receptor (TCR) complex phosphorylation by three-fold via the recruitment of Lck, with only a small, 2-20% increase in the effective affinity of the TCR for pMHC II. The affinity of CD4/pMHC II therefore appears to be set at a value that increases T-cell sensitivity by enhancing phosphorylation, without compromising ligand discrimination.This work was supported by the Wellcome Trust and the UK Medical Research Council. PJ was supported by grants from the Swedish Research Council (number: 623-2014- 6387 and 621-2014-3907). OD is supported by a Sir Henry Dale Fellowship jointly funded by the Wellcome Trust and the Royal Society (Grant Number: 098363)

    Phenotypic screen for oxygen consumption rate identifies an anti-cancer naphthoquinone that induces mitochondrial oxidative stress.

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    A hallmark of cancer cells is their ability to reprogram nutrient metabolism. Thus, disruption to this phenotype is a potential avenue for anti-cancer therapy. Herein we used a phenotypic chemical library screening approach to identify molecules that disrupted nutrient metabolism (by increasing cellular oxygen consumption rate) and were toxic to cancer cells. From this screen we discovered a 1,4-Naphthoquinone (referred to as BH10) that is toxic to a broad range of cancer cell types. BH10 has improved cancer-selective toxicity compared to doxorubicin, 17-AAG, vitamin K3, and other known anti-cancer quinones. BH10 increases glucose oxidation via both mitochondrial and pentose phosphate pathways, decreases glycolysis, lowers GSH:GSSG and NAPDH/NAPD+ ratios exclusively in cancer cells, and induces necrosis. BH10 targets mitochondrial redox defence as evidenced by increased mitochondrial peroxiredoxin 3 oxidation and decreased mitochondrial aconitase activity, without changes in markers of cytosolic or nuclear damage. Over-expression of mitochondria-targeted catalase protects cells from BH10-mediated toxicity, while the thioredoxin reductase inhibitor auranofin synergistically enhances BH10-induced peroxiredoxin 3 oxidation and cytotoxicity. Overall, BH10 represents a 1,4-Naphthoquinone with an improved cancer-selective cytotoxicity profile via its mitochondrial specificity
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