Papiloma de plexo coroideo del cuarto ventrículo cerebral : diagnóstico y tratamiento quirúrgico

Se trata de una perra mestiza, de ocho años de edad y unos 30 kg de peso, con hemiparesis e inclinación de la cabeza hacia el lado izquierdo. Tras realizar una resonancia magnética nuclear (RMN) se identificó la lesión, compatible con una neoplasia, en fosa posterior a nivel del cuarto ventrículo cerebral. El tratamiento quirúrgico consistió en una craneotomía suboccipital que permitió el acceso a la fosa posterior, para poder así extraer el tumor. El resultado obtenido tras la cirugía se puede considerar satisfactorio, si tenemos en cuenta el alto grado de morbilidad que supone trabajar en esta regiónHerein, we report the case of an eight-year-old, 30 kg, female mixed-breed dog, with hemiparesis and left head tilt. Magnetic resonance imaging led to identify the lession as a tumor in the caudal fossa of the fourth ventricle. The surgical treatment consisted of a suboccipital craniotomy, which allowed the access to the caudal fossa, and the xtirpation of the tumor. A satisfactory result was achieved after the surgery, if we consider the high sick rate involved when working in this region

Comparison of Poisson structures on moduli spaces

Let $X$ be a complex irreducible smooth projective curve, and let ${\mathbb L}$ be an algebraic line bundle on $X$ with a nonzero section $\sigma_0$. Let $\mathcal{M}$ denote the moduli space of stable Hitchin pairs $(E,\, \theta)$, where $E$ is an algebraic vector bundle on $X$ of fixed rank $r$ and degree $\delta$, and $\theta\, \in\, H^0(X,\, End(E)\otimes K_X\otimes{\mathbb L})$. Associating to every stable Hitchin pair its spectral data, an isomorphism of $\mathcal{M}$ with a moduli space $\mathcal{P}$ of stable sheaves of pure dimension one on the total space of $K_X\otimes{\mathbb L}$ is obtained. Both the moduli spaces $\mathcal{P}$ and $\mathcal{M}$ are equipped with algebraic Poisson structures, which are constructed using $\sigma_0$. Here we prove that the above isomorphism between $\mathcal{P}$ and $\mathcal{M}$ preserves the Poisson structures

A GIT interpretration of the Harder-Narasimhan filtration

An unstable torsion free sheaf on a smooth projective variety gives a GIT unstable point in certain Quot scheme. To a GIT unstable point, Kempf associates a "maximally destabilizing" 1-parameter subgroup, and this induces a filtration of the torsion free sheaf. We show that this filtration coincides with the Harder-Narasimhan filtration.Comment: 19 pages; Comments of the referees and references added. The construction for holomorphic pairs (Sections 6 and 7 from previous version) will appear in a further publication. To appear in Rev. Mat Complutens

Automorphisms of moduli spaces of vector bundles over a curve

Let X be an irreducible smooth complex projective curve of genus g at least 4. Let M(r,\Lambda) be the moduli space of stable vector bundles over X or rank r and fixed determinant \Lambda, of degree d. We give a new proof of the fact that the automorphism group of M(r,\Lambda) is generated by automorphisms of the curve X, tensorization with suitable line bundles, and, if r divides 2d, also dualization of vector bundles.Comment: 12 page

Einstein-Hermitian connection on twisted Higgs bundles

Let $X$ be a smooth projective variety over $\mathbb C$. We prove that a twisted Higgs vector bundle (\calE\, ,\theta) on $X$ admits an Einstein--Hermitian connection if and only if (\calE\, ,\theta) is polystable. A similar result for twisted vector bundles (no Higgs fields) was proved by S. Wang in \cite{Wa}. Our approach is simpler.Comment: To appear in Comptes rendus Mathematiqu

Moduli space of principal sheaves over projective varieties

Let G be a connected reductive group. The late Ramanathan gave a notion of (semi)stable principal G-bundle on a Riemann surface and constructed a projective moduli space of such objects. We generalize Ramanathan's notion and construction to higher dimension, allowing also objects which we call semistable principal G-sheaves, in order to obtain a projective moduli space: a principal G-sheaf on a projective variety X is a triple (P, E, psi), where E is a torsion free sheaf on X, P is a principal G-bundle on the open set U where E is locally free and psi is an isomorphism between E vertical bar(U) and the vector bundle associated to P by the adjoint representation

An approach to the seismic hazard at Teruel city associated to the Concud fault (NE Spain)

This paper presents the results ofa probabilistic seismic hazard analysis at Teruel city from seismological and geological information. The characteristic earthquake of the Concud fault (M ~ 6.8; recurrence period = 7.3 ±2.7 ka) has a probabilityof occurrence within a 500-yearperiod ranging from 2.3 to 26.1%. Its parameters fit precisely the magnitude-frequency pattern obtained from the historical seismicity of the Teruel and Jiloca grabens. This coherency supports an estimate of the maximum expectable seism within a 500-yearperiod: M = 5.4± 0.3. Empirical correlations indicate a potential intensity at Teruel overI= VII for this earthquake, and minimum peak ground acceleration ap = 0.105 g, higher than thatspecified by earthquake-resistant building regulationsSe presentan los resultados de un análisis probabilistico de peligrosidad sísmica en el entorno de Teruel a partir de la información geológica y sismológica. El terremoto característico de la falla de Concud (M ~ 6,8;periodo de retorno = 7,3 ±2,7 ka) tiene una probabilidad de ocurrencia en un plazo de 500 años de entre 2,3y26,1 %. Sus parámetros se ajustan bien a la extrapolación de la curva frecuencia-magnitud de la sismicidad histórica en el entorno de las fosas de Teruel yJiloca. En consecuencia, se hace una estimación de la magnitud del seísmo esperable en 500 años: M = 5,4± 0,3. Por correlación empírica se atribuye a éste una intensidad potencial en Teruel por encima de I = VII, y una aceleración de pico mínima ap = 0,105 g, superior a la especificada en la Norma Sismorresistent

Increased neurotransmitter release at the neuromuscular junction in a mouse model of polyglutamine disease

In Huntington's disease (HD), the expansion of polyglutamine (polyQ) repeats at the N terminus of the ubiquitous protein huntingtin (htt) leads to neurodegeneration in specific brain areas. Neurons degenerating in HD develop synaptic dysfunctions. However, it is unknown whether mutant htt impacts synaptic function in general. To investigate that, we have focused on the nerve terminals of motor neurons that typically do not degenerate in HD. Here, we have studied synaptic transmission at the neuromuscular junction of transgenic mice expressing a mutant form of htt (R6/1 mice).Wehave found that the size and frequency of miniature endplate potentials are similar in R6/1 and control mice. In contrast, the amplitude of evoked endplate potentials in R6/1 mice is increased compared to controls. Consistent with a presynaptic increase of release probability, synaptic depression under high-frequency stimulation is higher in R6/1 mice. In addition, no changes were detected in the size and dynamics of the recycling synaptic vesicle pool. Moreover, we have found increased amounts of the synaptic vesicle proteins synaptobrevin 1,2/VAMP 1,2 and cysteine string protein-α, and the SNARE protein SNAP-25, concomitant with normal levels of other synaptic vesicle markers. Our results reveal that the transgenic expression of a mutant form of htt leads to an unexpected gain of synaptic function. That phenotype is likely not secondary to neurodegeneration and might be due to a primary deregulation in synaptic protein levels. Our findings could be relevant to understand synaptic toxic effects of proteins with abnormal polyQ repeats. Copyright©2011 the authors.Instituto de Salud Carlos III (Centro de Investigación Biomédica en Red de Enfermedades Neurodegenerativas), the Spanish Ministry of Science and Innovation (BFU2007-66008 to R.F-C., SAF2009-08233 to J.J.L., and Juan de la Cierva contracts to J.L.R. and C.T.-Z.), Junta de Andalucía (P07-CVI- 02854, P06-CVI-02392), Comunidad Autónoma de Madrid, Fundación Ramón Areces, and Fondo Europeo de Desarrollo RegionalPeer Reviewe