Structural trends in the Southern Cook and Austral archipelagoes (South Central Pacific) based on an analysis of SEASAT data : geodynamic implications

Cette étude permet de caractériser deux directions structurales présentes dans les archipels des Iles Australes et Cook. Dans le cadre de la tectonique globale, les auteurs en discutent les implications géodynamiques

Calpain inhibition reduces NMDA receptor rundown in rat substantia nigra dopamine neurons.

Repeated activation of N-Methyl-d-aspartate receptors (NMDARs) causes a Ca2+-dependent reduction in NMDAR-mediated current in dopamine (DA) neurons of the substantia nigra pars compacta (SNc) in one week old rats; however, a Ca2+-dependent regulatory protein has not been identified. The role of the Ca2+-dependent cysteine protease, calpain, in mediating NMDAR current rundown was investigated. In brain slices from rats aged postnatal day 7-9 ('P7'), bath application of either of the membrane permeable calpain inhibitors, N-Acetyl-L-leucyl-L-leucyl-L-norleucinal (ALLN, 20 μM) or MDL-28170 (30 μM) significantly reduced whole-cell NMDAR current rundown. To investigate the role of the calpain-2 isoform, the membrane permeable calpain-2 inhibitor, Z-Leu-Abu-CONH-CH2-C6H3 (3, 5-(OMe)2 (C2I, 200 nM), was applied; C2I application significantly reduced whole cell NMDAR current rundown. Interestingly, ALLN but not C2I significantly reduced rundown of NMDA-EPSCs. These results suggest the calpain-2 isoform mediates Ca2+-dependent regulation of extrasynaptic NMDAR current in the first postnatal week, while calpain-1 might mediate rundown of synaptic NMDAR currents. One week later in postnatal development, at P12-P16 ('P14'), there was significantly less rundown in SNc-DA neurons, and no significant effect on rundown of either Ca2+ chelation or treatment with the calpain inhibitor, ALLN, suggesting that the rundown observed in SNc-DA neurons from two week-old rats might be Ca2+-independent. In conclusion, Ca2+-dependent rundown of extrasynaptic NMDAR currents in SNc DA neurons involves calpain-2 activation, but Ca2+- and calpain-2-dependent NMDAR current rundown is developmentally regulated.Non

Pratique de l'heuristique de pente et le package CAPUSHE

National audienceLa mise en oeuvre des méthodes "data-driven" de calibration de critères pénalisés, issues de l'heuristique de pente de Birgé et Massart (2007), implique des difficultés pratiques

Slope Heuristics: Overview and Implementation

RR INRIA-7223, Version 1Model selection is a general paradigm which includes many statistical problems. One of the most fruitful and popular approaches to carry it out is the minimization of a penalized criterion. Birgé and Massart (2006) have proposed a promising data-driven method to calibrate such criteria whose penalties are known up to a multiplicative factor: the ``slope heuristics''. Theoretical works validate this heuristic method in some situations and several papers report a promising practical behavior in various frameworks. The purpose of this work is twofold. First, an introduction to the slope heuristics and an overview of the theoretical and practical results about it are presented. Second, we focus on the practical difficulties occurring for applying the slope heuristics. A new practical approach is carried out and compared to the standard dimension jump method. All the practical solutions discussed in this paper in different frameworks are implemented and brought together in a Matlab graphical user interface called capushe

Maintenance of Synaptic Stability Requires Calcium-Independent Phospholipase A2 Activity

Phospholipases A2 (PLA2s) represent one of the largest groups of lipid-modifying enzymes. Over the years, significant advances have been made in understanding their potential physiological and pathological functions. Depending on their calcium requirement for activation, PLA2s are classified into calcium dependent and independent. This paper mainly focuses on brain calcium-independent PLA2 (iPLA2) and on the mechanisms by which they influence neuronal function and regulate synaptic plasticity. Particular attention will be given to the iPLA2γ isoform and its role in the regulation of synaptic glutamate receptors. In particular, the paper discusses the possibility that brain iPLA2γ deficiencies could destabilise normal synaptic operation and might contribute to the aetiology of some brain disorders. In this line, the paper presents new data indicating that iPLA2γ deficiencies accentuate AMPA receptor destabilization and tau phosphorylation, which suggests that this iPLA2 isoform should be considered as a potential target for the treatment of Tau-related disorders

Electrochromic window with lithium conductive polymer electrolyte

An electrochromic window was built using WO3 as electrochromic material and V2O5 as counterelectrode. Both were deposited onto ITO-coated glass panes by vacuum evaporation and were amorphous to x-ray diffraction. The electrolyte was a lithium-conducting polymer consisting of a poly(ethylene oxide)-lithium salt complex. The electrochemical characterization of electrodes was realized by cyclic voltammetry, coulometric titration, and impedance spectroscopy, which allowed the determination of the chemical diffusion coefficients of lithium into WO3 and V2O5. Potentiostatic cycling of the complete transmissive cell yields to a transmission variation from 41 to 13% at 633 nm with a response time of 10s at room temperature

Long-Term Recording of LTP in Cultured Hippocampal Slices

Long-term potentiation (LTP) was elicited by high frequency stimulation in hippocampal slices cultured on multi-electrode arrays. LTP lasting more than 1 h was recorded in 75% of slices, and a significant number of slices exhibited a non-decaying LTP that lasted more than 48 h. LTP induction was completely and reversibly blocked by an antagonist of the NMDA receptor, APV. Our results suggest the possibility of using chronic recording in hippocampal slices cultured on multi-electrode arrays to study the mechanisms underlying LTP maintenance and stabilization

Estrogen and Hippocampal Plasticity in Rodent Models

Accumulating evidence indicates that ovarian hormones regulate a wide variety of non-reproductive functions in the central nervous system by interacting with several molecular and cellular processes. A growing animal literature using both adult and aged rodent models indicates that 17β-estradiol, the most potent of the biologically relevant estrogens, facilitates some forms of learning and memory, in particular those that involve hippocampal-dependent tasks. A recently developed triple-transgenic mouse (3xTg-AD) has been widely used as an animal model of Alzheimer\u27s disease, as this mouse exhibits an age-related and progressive neuropathological phenotype that includes both plaque and tangle pathology mainly restricted to hippocampus, amygdala and cerebral cortex. In this report, we examine recent studies that compare the effects of ovarian hormones on synaptic transmission and synaptic plasticity in adult and aged rodents. A better understanding of the non-reproductive functions of ovarian hormones has far-reaching implications for hormone therapy to maintain health and function within the nervous system throughout aging