Successful Cognitive Aging in Rats: A Role for mGluR5 Glutamate Receptors, Homer 1 Proteins and Downstream Signaling Pathways

Normal aging is associated with impairments in cognition, especially learning and memory. However, major individual differences are known to exist. Using the classical Morris Water Maze (MWM) task, we discriminated a population of 24-months old Long Evans aged rats in two groups - memory-impaired (AI) and memory-unimpaired (AU) in comparison with 6-months old adult animals. AI rats presented deficits in learning, reverse memory and retention. At the molecular level, an increase in metabotropic glutamate receptors 5 (mGluR5) was observed in post-synaptic densities (PSD) in the hippocampus of AU rats after training. Scaffolding Homer 1b/c proteins binding to group 1 mGluR facilitate coupling with its signaling effectors while Homer 1a reduces it. Both Homer 1a and 1b/c levels were up-regulated in the hippocampus PSD of AU animals following MWM task. Using immunohistochemistry we further demonstrated that mGluR5 as well as Homer 1b/c stainings were enhanced in the CA1 hippocampus sub-field of AU animals. In fact mGluR5 and Homer 1 isoforms were more abundant and co-localized in the hippocampal dendrites in AU rats. However, the ratio of Homer 1a/Homer 1b/c bound to mGluR5 in the PSD was four times lower for AU animals compared to AI rats. Consequently, AU animals presented higher PKCγ, ERK, p70S6K, mTOR and CREB activation. Finally the expression of immediate early gene Arc/Arg3.1 was shown to be higher in AU rats in accordance with its role in spatial memory consolidation. On the basis of these results, a model of successful cognitive aging with a critical role for mGluR5, Homer 1 proteins and downstream signalling pathways is proposed here

Influence des paramètres process du procédé SLM sur les propriétés mécaniques du TA6V

National audienceThis study focuses on statistical analysis performed on five industrial parameters of SLM process inorder to correlate their impact on mechanical properties (E, YTS, UTS, and plastic deformation) ofTA6V samples. These parameters are reuse powder, layer thickness of powder, built orientation, HIPtreament and polishing of samples. Mechanical properties have been measured thanks to static tensiletest on 24 samples of TA6V. Some statistical laws have been defined thanks to MANOVA method andreveal that HIP treatment and polishing are the most important parameters to optimise yield tensilestress and ultimate tensile stress of TA6V.La présente étude porte sur l'utilisation d'un plan d'expériences fractionnaire visant à mettre en cor-rélation cinq facteurs industriels d'impression du procédé SLM (recyclage des poudres, épaisseur des couches, orientation de l'impression, HIP et polissage) sur les propriétés mécaniques en traction (E, Re, Rm et A%) de 24 éprouvettes réalisées en TA6V. La méthode MANOVA a été utilisée pour expliciter les lois statistiques extraites du dépouillement de l'étude. Les propriétés mécaniques ont été mesurées à l'aide d'essais de traction. Il s'avère que les post-traitements de HIP et de polissage des échantillons après fabrication sont les facteurs clés permettant l'optimisation des propriétés mécaniques telles que Re et Rm

LATTICE VIBRATIONS OF PHOSPHONIUM CHLORIDE AND PHOSPHONIUM CHLORIDE-d1d_{1} AND THE BARRIER TO TORSIONAL OSCILLATION.

Author Institution: Department of Chemistry, University of South CarolinaThe infrared spectra of polycrystalline $PH_{4}Cl$ and $PD_{4}Cl$ have been recorded from $33 cm^{-1}$ to $4000 cm^{-1}$ at $-170^{\circ}C$. Raman spectra of the two compounds were also obtained on poly-crystalline samples at the same temperature. Three external modes were observed: an infrared active translation at $140 cm^{-1}$, a Raman active translation at $114 cm^{-1}$ and a Raman active libration at $370 cm^{-1}$. Eight internal modes were also assigned. The barrier to torsional oscillation of the phosphonium ions was calculated from the Raman active libration and was found to be 8.5 kcal/mole for both $PH_{4}$ and $PD_{4}$ ions

Influence des paramètres process du procédé SLM sur les propriétés mécaniques du TA6V

National audienceThis study focuses on statistical analysis performed on five industrial parameters of SLM process inorder to correlate their impact on mechanical properties (E, YTS, UTS, and plastic deformation) ofTA6V samples. These parameters are reuse powder, layer thickness of powder, built orientation, HIPtreament and polishing of samples. Mechanical properties have been measured thanks to static tensiletest on 24 samples of TA6V. Some statistical laws have been defined thanks to MANOVA method andreveal that HIP treatment and polishing are the most important parameters to optimise yield tensilestress and ultimate tensile stress of TA6V.La présente étude porte sur l'utilisation d'un plan d'expériences fractionnaire visant à mettre en cor-rélation cinq facteurs industriels d'impression du procédé SLM (recyclage des poudres, épaisseur des couches, orientation de l'impression, HIP et polissage) sur les propriétés mécaniques en traction (E, Re, Rm et A%) de 24 éprouvettes réalisées en TA6V. La méthode MANOVA a été utilisée pour expliciter les lois statistiques extraites du dépouillement de l'étude. Les propriétés mécaniques ont été mesurées à l'aide d'essais de traction. Il s'avère que les post-traitements de HIP et de polissage des échantillons après fabrication sont les facteurs clés permettant l'optimisation des propriétés mécaniques telles que Re et Rm

Hardening precipitation and mechanical properties in new Mg-Mn-Y-Gd alloys

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Experimental study of the Ir-Rh system

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