Synapto-protective drugs evaluation in reconstructed neuronal network

Chronic neurodegenerative syndromes such as Alzheimer’s and Parkinson’s diseases, or acute syndromes such as ischemic stroke or traumatic brain injuries are characterized by early synaptic collapse which precedes axonal and neuronal cell body degeneration and promotes early cognitive impairment in patients. Until now, neuroprotective strategies have failed to impede the progression of neurodegenerative syndromes. Drugs preventing the loss of cell body do not prevent the cognitive decline, probably because they lack synapto-protective effects. The absence of physiologically realistic neuronal network models which can be easily handled has hindered the development of synapto-protective drugs suitable for therapies. Here we describe a new microfluidic platform which makes it possible to study the consequences of axonal trauma of reconstructed oriented mouse neuronal networks. Each neuronal population and sub-compartment can be chemically addressed individually. The somatic, mid axon, presynaptic and postsynaptic effects of local pathological stresses or putative protective molecules can thus be evaluated with the help of this versatile “brain on chip” platform. We show that presynaptic loss is the earliest event observed following axotomy of cortical fibers, before any sign of axonal fragmentation or post-synaptic spine alteration. This platform can be used to screen and evaluate the synapto-protective potential of several drugs. For instance, NAD+ and the Rho-kinase inhibitor Y27632 can efficiently prevent synaptic disconnection, whereas the broad-spectrum caspase inhibitor zVAD-fmk and the stilbenoid resveratrol do not prevent presynaptic degeneration. Hence, this platform is a promising tool for fundamental research in the field of developmental and neurodegenerative neurosciences, and also offers the opportunity to set up pharmacological screening of axon-protective and synapto-protective drugs

Buts et méthodes des analyses de profils spectraux au laboratoire de spectroscopie atomique du D.R.P.

On étudie en absorption les profils spectraux de diverses raies du mercure en présence de collisions Hg-Hg et Hg-gaz nobles. Différentes méthodes d’analyse spectrale sont utilisées suivant le domaine étudié. Des informations concernant les potentiels d’interaction sont ainsi obtenues

Discussion de l'influence de l'anisotropie du potentiel d'interaction sur l'élargissement et le déplacement, par collisions, de certaines raies de résonance

One studies the influence on the cross section of the anisotropy of the interaction potential. A method for the approximate resolution of the evolution equation valid for a J = 1 level, is proposed. It is shown that one must take into account the anisotropy in order to determine correctly the interaction potential in the excited state from experimental data.On étudie l'influence sur la section efficace de l'anisotropie du potentiel d'interaction. On introduit une méthode de résolution approchée de l'équation d'évolution, valable pour un niveau J = 1. On montre qu'il est nécessaire de tenir compte de l'anisotropie pour déterminer correctement le potentiel à l'état excité à partir des données expérimentales

Impact and quasistatic limit in the quantum-path theory of pressure broadening

The quantum-path theory of collision broadening involves a correlation function which can be calculated by infinite-order perturbation theory. From the expression obtained, both the impact and the quasistatic limit are easily derived. Application of the WKB method is discussed for the impact result

Étude comparative des sections efficaces d'élargissement et de dépolarisation par collisions

We write down the expressions of the cross-sections for orientation and alignment, using the model considered previously for the calculation of the optical cross-section. We show that the comparison of these cross-sections can give information about interaction potentials.On écrit les expressions des sections efficaces d'orientation et d'alignement, dans le cadre du modèle considéré précédemment pour le calcul de la section optique. On montre comment la comparaison de ces sections permet d'obtenir des informations sur les potentiels

Impact and quasistatic limit in the quantum-path theory of pressure broadening

The quantum-path theory of collision broadening involves a correlation function which can be calculated by infinite-order perturbation theory. From the expression obtained, both the impact and the quasistatic limit are easily derived. Application of the WKB method is discussed for the impact result

Experimental study of the mercury 4 047 Å line (6 3P 0-7 3S1) absorption profile in the presence of foreign gases

The absorption profile of the 4 047 Å line of mercury has been studied by means of the magnetic scanning method. The absorption chamber contained either only mercury and nitrogen, or a small amount of nitrogen and a perturbing noble gas.On étudie par balayage magnétique le profil d'absorption de la raie 4 047 Å du mercure. La cuve d'absorption contient soit un mélange de mercure et d'azote, soit un mélange de mercure et de gaz noble, avec une petite quantité d'azote

Line broadening on the basis of molecular eigenstates in high-density plasmas

Free and bound electrons in high-density plasmas have been treated by a self-consistent-field method applied to our previous quasi-molecule model (Phys. Rev. A, 40 (1989) 1983). The local density of the former and quantum parameters of the latter are given as functions of the internuclear distance R. Using these data in the framework of an adiabatic theory of line broadening, where ion dynamics and electron impact effects are included, we have calculated the NeX Lyman α and β line profiles and pointed out the excitation of several molecular satellites. For the NeX Lyman β line in particular, the molecular satellites $S_1(200 u\to 000 g)$ and $S_2(101 g\to 000u)$ are clearly visible on the near red wing in spite of large ion dynamics and electron impact broadening effects

DÉTERMINATION DE PROFILS SPECTRAUX PAR LA MÉTHODE DE BALAYAGE MAGNÉTIQUE

La méthode de balayage magnétique associée à un traitement des résultats tenant compte de la fonction d'appareil est utilisée pour la détermination des profils spectraux.A method including magnetic scanning and information treatment (taking into account the apparatus function) is used to study the shape of spectral lines