57 research outputs found

    La filosofía open source en la bioinformática

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    5 Pag., 2 Fig., 2 Fot.Desde hace una década el fenómeno open source o código abierto ha explotado y sus efectos se pueden ver en todas partes y también en la ciencia. Este modelo de software se centra en los beneficios prácticos de compartir el código, más allá de cuestiones morales y filosóficas. Así, en la ciencia, los programas open source permiten que investigadores de todo el mundo pongan a prueba e incluso mejoren soluciones a problemas científicos, como si fueran experimentos a escala global.Bruno Contreras Moreira es Investigador de la Fundación ARAID y desarrolla su trabajo en el Laboratorio de Biología Computacional, Estación Experimental de Aula Dei (Zaragoza), perteneciente al CSIC.Peer reviewe

    Persistent Quantitative Vitality of Stem Cell Graft Is Necessary for Stabilization of Functional Brain Networks After Stroke

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    Stem cell treatment after stroke has demonstrated substantial outcome improvement. However, monitoring of stem cell fate in vivo is still challenging and not routinely performed, yet important to quantify the role of the implanted stem cells on lesion improvement; in several studies even mortality of the graft has been reported. Resting state functional magnetic resonance imaging (rs-fMRI) is a highly sensitive imaging modality to monitor the brain-wide functional network alterations of many brain diseases in vivo. We monitor for 3 months the functional connectivity changes after intracortical stem cell engraftment in large, cortico-striatal (n = 9), and in small, striatal (n = 6) ischemic lesions in the mouse brain with non-invasive rs-fMRI on a 9.4T preclinical MRi scanner with GE-EPI sequence. Graft vitality is continuously recorded by bioluminescence imaging (BLI) roughly every 2 weeks after implantation of 300 k neural stem cells. In cortico-striatal lesions, the lesion extension induces graft vitality loss, in consequence leading to a parallel decrease of functional connectivity strength after a few weeks. In small, striatal lesions, the graft vitality is preserved for the whole observation period and the functional connectivity is stabilized at values as in the pre-stroke situation. But even here, at the end of the observation period of 3 months, the functional connectivity strength is found to decrease despite preserved graft vitality. We conclude that quantitative graft viability is a necessary but not sufficient criterion for functional neuronal network stabilization after stroke. Future studies with even longer time periods after stroke induction will need to identify additional players which have negative influence on the functional brain networks

    Stem Cell Mediation of Functional Recovery after Stroke in the Rat

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    This is an open-access article distributed under the terms of the Creative Commons Attribution License.[Background]: Regenerative strategies of stem cell grafting have been demonstrated to be effective in animal models of stroke. In those studies, the effectiveness of stem cells promoting functional recovery was assessed by behavioral testing. These behavioral studies do, however, not provide access to the understanding of the mechanisms underlying the observed functional outcome improvement. [Methodology/Principal Findings]: In order to address the underlying mechanisms of stem cell mediated functional improvement, this functional improvement after stroke in the rat was investigated for six months after stroke by use of fMRI, somatosensory evoked potentials by electrophysiology, and sensorimotor behavior testing. Stem cells were grafted ipsilateral to the ischemic lesion. Rigorous exclusion of spontaneous recovery as confounding factor permitted to observe graft-related functional improvement beginning after 7 weeks and continuously increasing during the 6-month observation period. The major findings were i) functional improvement causally related to the stem cells grafting; ii) tissue replacement can be excluded as dominant factor for stem cell mediated functional improvement; iii) functional improvement occurs by exclusive restitution of the function in the original representation field, without clear contributions from reorganization processes, and iv) stem cells were not detectable any longer after six months. [Conclusions/Significance]: A delayed functional improvement due to stem cell implantation has been documented by electrophysiology, fMRI and behavioral testing. This functional improvement occurred without cells acting as a tissue replacement for the necrotic tissue after the ischemic event. Combination of disappearance of grafted cells after six months on histological sections with persistent functional recovery was interpreted as paracrine effects by the grafted stem cells being the dominant mechanism of cell activity underlying the observed functional restitution of the original activation sites. Future studies will have to investigate whether the stem cell mediated improvement reactivates the original representation target field by using original connectivity pathways or by generating/activating new ones for the stimulus.Financial support from the Hertie Foundation (Germany), and EU grants of the FP-6: DiMI (LSHB-CT-2005-512146), EMIL (LSHC-CT-2004-503569) and Stem Stroke (LSHB-CT-2006-037526) are gratefully acknowledged.Peer Reviewe

    Magnetization-transfer P-31 NMR of biochemical exchange in vivo: Application to creatine kinase kinetics

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    Phosphorus-31 saturation-transfer NMR spectroscopy provides an elegant means to study fluxes through the creatine kinase reaction in human skeletal muscle. To obtain reliable quantitative kinetic information, experimental imperfections, such as incomplete saturation and radiofrequency bleed over need to be addressed appropriately. In resting muscle, creatine kinase was near equilibrium both in normal controls and in a patient with impaired oxidative phosphorylation. Oral intake of high doses of creatine monohydrate for several days resulted in significantly increased concentrations of phosphocreatine but had no measurable effect on the phosphocreatine resynthesis rate in resting muscle

    Early prediction of functional recovery after experimental stroke: functional magnetic resonance imaging, electrophysiology, and behavioral testing in rats

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    et al.Therapeutic success of treatment of cerebral diseases must be assessed in terms of functional outcome. In experimental stroke studies, this has been limited to behavioral studies combined with morphological evaluations and single time point functional magnetic resonance imaging (fMRI) measurements butlacking the access to understanding underlying mechanisms for alterations in brain activation. Using a recently developed blood oxygenation level-dependent fMRI protocol to study longitudinal and intraindividual profiles of functional brain activation in the somatosensory system, we have demonstrated activation reemergence in the original representation field as the basic principle offunctional recovery from experimental stroke. No plastic reorganization has been observed atany time point during 7 weeks after stroke induction. Applying combined recording of fMRI and somatosensory evoked potentials, we observed a tight coupling ofelectrical brain activity and hemodynamic response atall times, indicating persistentpreservation ofneurovascular coupling. Identification of functional brain recovery mechanisms has important implications for the understanding of brain plasticity after cerebral lesions, whereas preservation of neurovascular coupling is important for the clinical translation of fMRI.This work was supported by grants from the Hertie Foundation (Functional Brain Imaging) and through European Union Project LSHB-CT-2006-037526 (StemStroke).Peer reviewe

    A longitudinal and totally noninvasive fMRI protocol in rats

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