Age-dependent decrease in glutamine synthetase expression in the hippocampal astroglia of the triple transgenic Alzheimer's disease mouse model : mechanism for deficient glutamatergic transmission?

Astrocytes are fundamental for brain homeostasis and the progression and outcome of many neuropathologies including Alzheimer's disease (AD). In the triple transgenic mouse model of AD (3xTg-AD) generalised hippocampal astroglia atrophy precedes a restricted and specific beta-amyloid (A beta) plaque-related astrogliosis. Astrocytes are critical for CNS glutamatergic transmission being the principal elements of glutamate homeostasis through maintaining its synthesis, uptake and turnover via glutamate-glutamine shuttle. Glutamine synthetase (GS), which is specifically expressed in astrocytes, forms glutamine by an ATP-dependent amination of glutamate. Here, we report changes in GS astrocytic expression in two major cognitive areas of the hippocampus (the dentate gyrus, DG and the CA1) in 3xTg-AD animals aged between 9 and 18 months. We found a significant reduction in Nv (number of cell/mm(3)) of GS immunoreactive (GS-IR) astrocytes starting from 12 months (28.59%) of age in the DG, and sustained at 18 months (31.65%). CA1 decrease of GS-positive astrocytes Nv (33.26%) occurs at 18 months. This Nv reduction of GSIR astrocytes is paralleled by a decrease in overall GS expression (determined by its optical density) that becomes significant at 18 months (21.61% and 19.68% in DG and CA1, respectively). GS-IR Nv changes are directly associated with the presence of A beta deposits showing a decrease of 47.92% as opposed to 23.47% in areas free of A beta. These changes in GS containing astrocytes and GS-immunoreactivity indicate AD-related impairments of glutamate homeostatic system, at the advanced and late stages of the disease, which may affect the efficacy of glutamatergic transmission in the diseased brain that may contribute to the cognitive deficiency.

La aportación de W. von Humboldt a la gramática vasca

[EN] The aim of this paper is to introduce the main contributions of Humboldt to the study of the Basque grammar. His methodological innovations and the influence he had on european linguists are pointed out, the grammatical sources available to him are mentioned and his woks on Basque grammar are enumerated. Some of Humboldt's most interesting analysis are mentioned and are placed in the former and later tradition of the Basque grammar.

Materiales vascos del legado de Wilhelm von Humboldt: la relevancia de Astarloa y el Plan de Lenguas

Este artículo es traducción del original alemán «Zum Stellenwert Astarloas und des Plan de Lenguas», publicado en B. Hurch (ed.), Die baskischen Materialien aus dem Nachlaß Wilhelm von Humboldts. Astarloa, Charpentier, Fréret, Aizpitarte und anderes. Paderborn: Schöningh, pp. 21-42. La traducción al español es obra de Oroitz Jauregi y ha sido revisada por Ricardo Gómez y Bernhard Hurch.

El viajero Wilhelm von Humboldt y sus sucesores: caracterización cultural del País Vasco en las descripciones de viaje del siglo XIX

Berta Raposo Fernández e Ingrid García Wistädt (editoras)

The von Neumann-Morgenstern stable sets for 2x2 games

We analyze the von Neumann and Morgenstern stable sets for the mixed extension of 2 2 games when only single profitable deviations are allowed. We show that the games without a strict Nash equilibrium have a unique vN&M stable set and otherwise they have infinite sets.