Time filter

Source Type

Grenoble, France

Université Joseph Fourier , often known as UJF, is a French university situated in the city of Grenoble and focused on the fields of science, technologies and health. This institution was previously also called Université Grenoble I . Wikipedia.

Bachasson D.,Joseph Fourier University
Arthritis care & research | Year: 2013

To assess quadriceps strength and fatigability by using femoral nerve magnetic stimulation (FNMS) and their relationship to exercise capacity in patients with fibromyalgia syndrome (FMS) and healthy controls. Twenty-two women (11 with FMS, 11 controls) performed a maximal incremental cycling test and a quadriceps fatigue test on 2 separate visits. For quadriceps assessment, we used FNMS during and after maximum voluntary contraction (MVC) to evaluate central and peripheral factors of neuromuscular fatigue. Subjects performed sets of 10 intermittent (5 seconds on/5 seconds off) isometric contractions starting at 10% MVC, in 10% MVC increments from one set to another until exhaustion. Neuromuscular fatigue was assessed with FNMS after each set. FMS patients had reduced initial MVC compared to controls (mean ± SD 102 ± 18 versus 120 ± 24 Nm; P < 0.05) without significant impairment of voluntary activation (mean ± SD 93.5% ± 3.0% versus 93.1% ± 3.4%; P = 0.74). During the fatigue task, FMS patients exhibited a greater fall in evoked muscular responses (mean ± SD -26% ± 6% versus -16% ± 8% at set 50% MVC; P < 0.05), but not in MVC (mean ± SD -24% ± 7% versus -19% ± 4% at set 50% MVC; P = 0.12). During the cycling test, FMS patients had lowered maximal exercise capacity and an enhanced rate of perceived exertion (RPE) compared to controls. The percent reduction in evoked muscular responses during the quadriceps fatigue test correlated with maximum oxygen consumption (r = 0.56, P < 0.05) and RPE at submaximal intensity (r = 0.84, P < 0.05) during cycling. Greater impairment in muscle contractility is associated with enhanced perception of exertion and reduced maximal exercise capacity in FMS patients. Neuromuscular impairments should be considered as an important factor underlying functional limitations in FMS patients. Copyright © 2013 by the American College of Rheumatology. Source

In RNA silencing, small RNAs produced by the RNase-III Dicer guide Argonaute-like proteins as part of RNA-induced silencing complexes (RISC) to regulate gene expression transcriptionally or post-transcriptionally. Here, we have characterized the RNA silencing machinery and exhaustive small RNAome of Toxoplasma gondii, member of the Apicomplexa, a phylum of animal- and human-infecting parasites that cause extensive health and economic damages to human populations worldwide. Remarkably, the small RNA-generating machinery of Toxoplasma is phylogenetically and functionally related to that of plants and fungi, and accounts for an exceptionally diverse array of small RNAs. This array includes conspicuous populations of repeat-associated small interfering RNA (siRNA), which, as in plants, likely generate and maintain heterochromatin at DNA repeats and satellites. Toxoplasma small RNAs also include many microRNAs with clear metazoan-like features whose accumulation is sometimes extremely high and dynamic, an unexpected finding given that Toxoplasma is a unicellular protist. Both plant-like heterochromatic small RNAs and metazoan-like microRNAs bind to a single Argonaute protein, Tg-AGO. Toxoplasma miRNAs co-sediment with polyribosomes, and thus, are likely to act as translational regulators, consistent with the lack of catalytic residues in Tg-AGO. Mass spectrometric analyses of the Tg-AGO protein complex revealed a common set of virtually all known RISC components so far characterized in human and Drosophila, as well as novel proteins involved in RNA metabolism. In agreement with its loading with heterochromatic small RNAs, Tg-AGO also associates substoichiometrically with components of known chromatin-repressing complexes. Thus, a puzzling patchwork of silencing processor and effector proteins from plant, fungal and metazoan origin accounts for the production and action of an unsuspected variety of small RNAs in the single-cell parasite Toxoplasma and possibly in other apicomplexans. This study establishes Toxoplasma as a unique model system for studying the evolution and molecular mechanisms of RNA silencing among eukaryotes. Source

Lectins and adhesins are involved in bacterial adhesion to host tissues and mucus during early steps of infection. We report the characterization of BC2L-C, a soluble lectin from the opportunistic pathogen Burkholderia cenocepacia, which has two distinct domains with unique specificities and biological activities. The N-terminal domain is a novel TNF-α-like fucose-binding lectin, while the C-terminal part is similar to a superfamily of calcium-dependent bacterial lectins. The C-terminal domain displays specificity for mannose and l-glycero-d-manno-heptose. BC2L-C is therefore a superlectin that binds independently to mannose/heptose glycoconjugates and fucosylated human histo-blood group epitopes. The apo form of the C-terminal domain crystallized as a dimer, and calcium and mannose could be docked in the binding site. The whole lectin is hexameric and the overall structure, determined by electron microscopy and small angle X-ray scattering, reveals a flexible arrangement of three mannose/heptose-specific dimers flanked by two fucose-specific TNF-α-like trimers. We propose that BC2L-C binds to the bacterial surface in a mannose/heptose-dependent manner via the C-terminal domain. The TNF-α-like domain triggers IL-8 production in cultured airway epithelial cells in a carbohydrate-independent manner, and is therefore proposed to play a role in the dysregulated proinflammatory response observed in B. cenocepacia lung infections. The unique architecture of this newly recognized superlectin correlates with multiple functions including bacterial cell cross-linking, adhesion to human epithelia, and stimulation of inflammation. Source

Braun J.,Joseph Fourier University
Nature Geoscience | Year: 2010

Plate tectonic theory suggests that present-day topography can be explained by the repeated interactions between the tectonic plates moving along Earth's surface. However, mounting evidence indicates that a significant proportion of Earth's topography results from the viscous stresses created by flow within the underlying mantle, rather than by the moving plates. This dynamic topography is transient, varying as mantle flow changes, and is characterized by small amplitudes and long wavelengths. It is therefore often hidden by or confused with the more obvious topographic anomalies resulting from horizontal tectonic movements. However, dynamic topography can influence surface processes and thus enter the geological record; it has, for example, played a role in the establishment of Amazon drainage patterns. In turn, surface processes such as the erosion of topographical anomalies could affect mantle flow. This emerging view of dynamic topography suggests that the concept of plate tectonics as the driver of surface deformation needs to be extended to include the vertical coupling between the mantle and the surface. Unravelling this coupling back in time with the help of models and the geological record can potentially provide unprecedented insights into past mantle dynamics. © 2010 Macmillan Publishers Limited. All rights reserved. Source

Girard A.,Joseph Fourier University
Automatica | Year: 2012

In this paper, we consider the problem of controller design using approximately bisimilar abstractions with an emphasis on safety and reachability specifications. We propose abstraction-based approaches to controller synthesis for both types of specifications. We start by synthesizing a controller for an approximately bisimilar abstraction. Then, using a concretization procedure, we obtain a controller for our initial system that is proved "correct by design". We provide guarantees of performance by giving estimates of the distance of the synthesized controller to the maximal (i.e.; the most permissive) safety controller or to the time-optimal reachability controller. Finally, we use these techniques, combined with discrete approximately bisimilar abstractions of switched systems developed recently, for switching controller synthesis. © 2012 Elsevier Ltd. All rights reserved. Source

Discover hidden collaborations