Isolation of mineralizing Nestin+ Nkx6.1+ vascular muscular cells from the adult human spinal cord

Background: The adult central nervous system (CNS) contains different populations of immature cells that could possibly be used to repair brain and spinal cord lesions. The diversity and the properties of these cells in the human adult CNS remain to be fully explored. We previously isolated Nestin(+) Sox2(+) neural multipotential cells from the adult human spinal cord using the neurosphere method (i.e. non adherent conditions and defined medium). -- Results: Here we report the isolation and long term propagation of another population of Nestin(+) cells from this tissue using adherent culture conditions and serum. QPCR and immunofluorescence indicated that these cells had mesenchymal features as evidenced by the expression of Snai2 and Twist1 and lack of expression of neural markers such as Sox2, Olig2 or GFAP. Indeed, these cells expressed markers typical of smooth muscle vascular cells such as Calponin, Caldesmone and Acta2 (Smooth muscle actin). These cells could not differentiate into chondrocytes, adipocytes, neuronal and glial cells, however they readily mineralized when placed in osteogenic conditions. Further characterization allowed us to identify the Nkx6.1 transcription factor as a marker for these cells. Nkx6.1 was expressed in vivo by CNS vascular muscular cells located in the parenchyma and the meninges. -- Conclusion: Smooth muscle cells expressing Nestin and Nkx6.1 is the main cell population derived from culturing human spinal cord cells in adherent conditions with serum. Mineralization of these cells in vitro could represent a valuable model for studying calcifications of CNS vessels which are observed in pathological situations or as part of the normal aging. In addition, long term propagation of these cells will allow the study of their interaction with other CNS cells and their implication in scar formation during spinal cord injury.

Oihartzunak-hitz sustraituak

Este artículo se puede encontrar en castellano en la revista Cuadernos de Psicomotricidad, nº 29,(2005) titulado Resonancias, y nº 30, (2005) titulado Palabras enraizadas.

Eredu latindarraren eragina euskal deklinabidearen XIX. mendeko deskribapenetan

R. Etxepare, R. Gómez & J. A. Lakarra (arg.), Beñat Oihartzabali Gorazarre - Festschrift for Bernard Oyharçabal. Donostia-San Sebastián: Gipuzkoako Foru Aldundia & UPV/EHU.

Literaturaren zertarakoa, itzulpenak eta hizkuntzaren auzia Orixerengan

Ejemplar dedicado a: Beñat Oihartzabali gorazarre - Festchrift for Bernard Oyharçabal/ Ricardo Etxepare, Ricardo Gómez, Joseba Andoni Lakarra ( eds.)

Análisis de la psicomotricidad en el inicio de la escolarización : un estudio psicogenético y observacional del salto durante el tercer año de vida

428 p. : gráf.

Euskal Gramatika prozesatzen: Hastapenetako zenbait emaitza

Beñat Oihartzabali Gorazarre: Festschrift for Bernard Oyharçabal / Ricardo Etxepare, Ricardo Gómez, Joseba Andoni Lakarra (arg./eds)

Physiological modules for generating discrete and rhythmic movements: action identification by a dynamic recurrent neural network

In this study we employed a dynamic recurrent neural network (DRNN) in a novel fashion to reveal characteristics of control modules underlying the generation of muscle activations when drawing figures with the outstretched arm. We asked healthy human subjects to perform four different figure-eight movements in each of two workspaces (frontal plane and sagittal plane). We then trained a DRNN to predict the movement of the wrist from information in the EMG signals from seven different muscles. We trained different instances of the same network on a single movement direction, on all four movement directions in a single movement plane, or on all eight possible movement patterns and looked at the ability of the DRNN to generalize and predict movements for trials that were not included in the training set. Within a single movement plane, a DRNN trained on one movement direction was not able to predict movements of the hand for trials in the other three directions, but a DRNN trained simultaneously on all four movement directions could generalize across movement directions within the same plane. Similarly, the DRNN was able to reproduce the kinematics of the hand for both movement planes, but only if it was trained on examples performed in each one. As we will discuss, these results indicate that there are important dynamical constraints on the mapping of EMG to hand movement that depend on both the time sequence of the movement and on the anatomical constraints of the musculoskeletal system. In a second step, we injected EMG signals constructed from different synergies derived by the PCA in order to identify the mechanical significance of each of these components. From these results, one can surmise that discrete-rhythmic movements may be constructed from three different fundamental modules, one regulating the co-activation of all muscles over the time span of the movement and two others elliciting patterns of reciprocal activation operating in orthogonal directions.

Physiological modules for generating discrete and rhythmic movements: Component analysis of EMG signals

A central question in Neuroscience is that of how the nervous system generates the spatiotemporal commands needed to realize complex gestures, such as handwriting. A key postulate is that the central nervous system (CNS) builds up complex movements from a set of simpler motor primitives or control modules. In this study we examined the control modules underlying the generation of muscle activations when performing different types of movement: discrete, point-to-point movements in eight different directions and continuous figure-eight movements in both the normal, upright orientation and rotated 90 degrees. To test for the effects of biomechanical constraints, movements were performed in the frontal-parallel or sagittal planes, corresponding to two different nominal flexion/abduction postures of the shoulder. In all cases we measured limb kinematics and surface electromyographic activity (EMB) signals for seven different muscles acting around the shoulder. We first performed principal component analysis (PCA) of the EMG signals on a movement-by-movement basis. We found a surprisingly consistent pattern of muscle groupings across movement types and movement planes, although we could detect systematic differences between the PCs derived from movements performed in each sholder posture and between the principal components associated with the different orientations of the figure. Unexpectedly we found no systematic differences between the figute eights and the point-to-point movements. The first three principal components could be associated with a general co-contraction of all seven muscles plus two patterns of reciprocal activatoin. From these results, we surmise that both "discrete-rhythmic movements" such as the figure eight, and discrete point-to-point movement may be constructed from three different fundamental modules, one regulating the impedance of the limb over the time span of the movement and two others operating to generate movement, one aligned with the vertical and the other aligned with the horizontal.

Studying the influence of substitutional elements on mechanical behavior of Alloy 718

In nickel-based superalloys, substitutional solute species have a strong impact on in service mechanical properties as well as on oxidation and corrosion resistances. In alloy 718, recent studies carried out by tensile tests highlighted the fact that refractory solute species are able to interact strongly with mobile dislocations during plastic deformation, generating dynamic strain ageing, and, in wide ranges of tests temperatures and strain rates, Portevin-Le Chatelier effect. The precise nature of the substitutional element responsible for such a dynamic interaction is still subject to debate. We addressed this question by means of mechanical spectroscopy studies of alloy 718 and various related alloys corresponding to monitored changes in the chemical composition. Only a single internal friction relaxation peak has been observed for all the studied alloys. By analyzing the damping behavior of these alloys at different imposed solicitation frequencies by sweeping a large temperatures range, the activation energies of the relaxation process and the type of mechanism involved have been determined. The process is a "Zener relaxation" in the alloys, i.e. a substitutional atoms dipole reorientation under applied stress. The results tend to prove that Niobium is not involved in the relaxation process whereas Molybdenum content seems to play an important role in the relaxation intensity.

Irakaslearen esku hartzea psikomotrizitate saioan

[eus] Bernard Aucouturier pedagogoak sortutako praktika psikomotorrak, bide motrizetik abiatuta, haurraren heltze psikologikoa helburu duen metodoa da. Haurra bere garapenean ulertu eta lagundu ahal izateko psikomotrizitatearen beharraz kontziente izanik eta Aucouturier metodologia abiapuntutzat hartuta, lan honetan, hezitzaile bakoitzari bere praktika hobetzeko eta horren inguruan hausnartzeko erreferentzia markoa eskainiko zaio. Horretarako, bi urteko gela bateko irakaslearen esku hartzearen analisiaren bidez, jardunaren egokitasuna ebaluatzearekin batera, esku hartzea hobetzeko proposamena eskainiko da. Izan ere, hezitzailearen oinarrizko funtzioa praktika psikomotorrean modu ez zuzentzailean esku hartzeko egoerak sortzea da, horretarako formakuntza pertsonal eta profesional sendo eta zorrotza ezinbestekoa izanik.