Ionospheric storm effects at the equatorial anomaly Mansilla, Gustavo Adolfo Ionospheric disturbances produced at the equatorial anomaly (EA) region during some geomagnetic storms were investigated using hourly NmF2 peak electron density of F2-layer values from stations located at equatorial and low geomagnetic latitudes. In general, increases (positive storm effects) or decreases (negative storm effects) of NmF2 (proportional to square of foF2 ionospheric critical frequency) in the nighttime hours were observed at equatorial latitudes in response to storms started during sunset hours. For the storm onset occurring during morning hours an intensification of the fountain effect was produced. For the storms starting in the nighttime hours no significant disturbances appeared at the crest regions in association with the initial positive or negative effects observed at the trough in the daytime. During the recovery phase in general significant delayed positive storm effects occurred mainly at low latitudes and a minor degree at equatorial latitudes. Possible physical mechanisms for controlling the morphology of the ionosphere during these events are considered.

Colapso estructural bajo cargas explosivas Luccioni, Bibiana Maria; Ambrosini, Ricardo Daniel; Danesi, Rodolfo Francisco Las estructuras civiles no son generalmente diseñadas para resistir cargas dinámicas de muy corta duración y gran amplitud como las generadas por explosiones e impacto. Hasta hace muy poco tiempo, la consideración de cargas explosivas debidas a un ataque terrorista se limitaba principalmente a estructuras tales como estructuras militares, centrales nucleares, embajadas, etc. En este trabajo se presenta la simulación del proceso de destrucción de estructuras de hormigón producido por la detonación de cargas explosivas. Dicho estudio se realiza mediante un hidrocódigo que considera la interacción fluido (aire)- estructura. Se describen en el trabajo los modelos materiales utilizados para el hormigón y mampostería.Dichos modelos incluyen la simulación del fenómeno de desintegración o fractura del material que permite eliminar al mismo del cálculo para simular erosión o discontinuidades producidas en el material por la carga explosiva. Se presentan, además, las distintas estrategias de calculo utilizadas en la simulación del proceso completo, desde la detonación del explosivo, hasta la caída del edificio.

The Toeplitz algebra on the Bergman space coincides with its commutator ideal Suarez, Fernando Daniel Let L^2-a be the Bergman space of the unit disk and T(L^2_a) be the Banach algebra generated by Toeplitz operators T_f , with f ∈ L∞. We prove that the closed bilateral ideal of T(L2a) generated by operators of the form T_fT_g − T_gT_f coincides with T(L^2_a).

Flea parasites of small mammals in the Monte Desert biome in Argentina with new host and locality records Lareschi, Marcela; Ojeda, Ricardo Alberto; Linardi, Pedro M. Fleas associated with small mammals from the Argentinean Monte Desert, were examined. The research was carried out in Ñacuñán Biosphere Reserve (34°02´S, 67°58´W), in the Chaqueña Biogeographic Subregion of the Neotropical Region. Mammal species trapped were as follows: Rodentia, Muridae, Sigmodontinae: Akodon molinae Contreras, 1968 (N = 44), Graomys griseoflavus (Waterhouse, 1837) (N = 15), Calomys musculinus (Thomas, 1913) (N = 12), and Eligmodontia typus F. Cuvier, 1837 (N = 7); Didelphiomorphia, Didelphidae, Mamorsinae: Thylamys pusillus (Desmarest, 1804) (N = 1). A total of 236 fleas were collected: Stephanocircidae, Craneopsyllinae: Craneopsylla minerva wolffhuegeli (Rothschild, 1909); Rhopalopsyllidae, Rhopalopsyllinae: Polygenis (Polygenis) bohlsi bohlsi (Wagner, 1901), Polygenis (Polygenis) platensis cisandinus (Jordan, 1939) and Polygenis (Neopolygenis) puelche Del Ponte, 1963; Rhopalopsyllidae, Parapsyllinae: Ectinorus (Ectinorus) barrerai Jordan, 1939. High values of total mean abundance (MA = 2.99) and total prevalence (P = 73.41%) were obtained. A. molinae (MA = 3.14; P = 93.18; flea specific richness S = 5; Shannon specific diversity index H = 1.25) and G. griseoflavus (MA = 6.40; P = 100%; S = 5; H = 0.76) showed the highest values of the infestation parameters. No fleas were collected from E. typus, possibly because of its habits. Fleas associated with T. pusillus are reported for the first time. Our collections extend the western limits of the distribution of both P. (N.) puelche and P. (P.) b. bohlsi. In addition, new host species are reported for every flea species and subspecies, and seven host-flea associations are mentioned for the first time.

Study of degenerate bifurcations in maps: A feedback systems approach D'amico, Edith Maria Belen; Moiola, Jorge Luis; Paolini, Eduardo Emilio The dynamical behavior of nonlinear maps undergoing degenerate period doubling or degenerate Hopf bifurcations is studied via a frequency-domain approach. The technique is based on a discrete-time feedback representation of the system and the application of the well-known engineering tools of harmonic balance to approximate the emerging solutions. More specifically, the results are a higher-order extension of the previous developments obtained by the authors for nondegenerate bifurcations. Two examples are included for illustration. Read More: http://www.worldscientific.com/doi/abs/10.1142/S0218127404010266

Regularidad con respecto a parámetros de las soluciones de problemas parabólicos abstractos semilineales Spies, Ruben Daniel Se determinan condiciones suficientes bajo las cuales la solucion z(t;q) de un problema parabólico abstracto semilineal de la forma d/dt z(t)=A(q)z(t) + F(q,t,z(t)) es derivable Fréchet con respecto al parámetro q. Se prueba que la derivada de Fréchet D_q z(t;q) es la solución de un problema de valores iniciales lineal no homogéneo en el espacio de estados Z.  Se provee una forma explícita para este problema de valores iniciales que constituye la llamada "ecuación de sensitividad" para la solución z(t;q).

El alimento, la cocina étnica, la gastronomía nacional. Elemento patrimonial y un referente de la identidad cultural. Torres, Graciela Felisa  En el artículo se analiza la cualidad de elemento patrimonial del alimento y el conjunto denominado cocina nacional.Para ello se define brevemente el concepto de Patrimonio en sus vertientes tangible e intangible.El alimento que se encuadraría enla esfera de lo intangible, se constituye en el eje del análisis y se establecen sus relaciones tanto con el Patrimonio en general como con el proceso de construcción de la identidad de un grupo social determinado. Se consideran algunos platos o comidas propias de la región Noroeste como ejemplos de referentes identitarios. 

Resistencias al orden formalizado por la Constitución de Mendoza de 1854 en el ámbito de la campaña Sanjurjo, Ines Elena El trabajo analiza la efectiva aplicación de los principios del moderno constitucionalismo en Mendoza luego de formalizado el orden liberal mediante la carta magna provincial de 1854. Busca averiguar, para el período de vigencia de esa constitución (1854-1895), si no obstante el proceso de complejización del aparato del Estado provincial y la política de afianzamiento de su potestad sobre el territorio, quedaron espacios que escaparon a ese poder, o se dieron prácticas resistentes a los principios en boga. Se ha puesto particular atención a las localidades de la campaña, que por las distancias o la poca accesibilidad, se estima eran poco proclives a los cambios y estaban menos expuestas al control estatal.; The work analyzes the effective application of the principles of the modern constitutionalism in Mendoza after it was formalized the liberal order by means of the Constitution of 1854. The investigation tries to quarrel if in the period of this constitution life (1854-1895), nevertheless the bigger complexity of the state mechanisms and the politics of strengthening the legal authority on the territory, there were spaces that escaped to this power, or practices resistant to the principles in vogue. The work has put on particular attention to the rural localities, which for the distances or small accessibility, is estimated they were less inclined to the changes and less exposed to the state control.

Assignment of Paternity in a Judicial Dispute Between Two Neighbor Holstein Dairy Farmers Liron, Juan Pedro; Ripoli, María Verónica; Peral Garcia, Pilar; Giovambattista, Guillermo DNA profiling was used as evidence to assign paternity in a dispute between two neighbors in a judicial case of undue appropriation of cattle offspring from five alleged Holstein sires. Five offspring were genotyped using ten genetic markers (nine microsatellites and the BOLA-DRB3 locus). The computer program CERVUS was used to estimate the LOD score values and the confidence of paternity assignments. The results presented here show that three out of five paternity cases were assigned at 95% of confidence to a single sire with a LOD score ranging from 2.53 to 3.55. A fourth male was assigned using its D value. Finally, all alleged sires were excluded from the paternity of the fifth offspring, probably due to the existence of an non-sampled male in the studied population. We concluded that the likelihood-based approach, included into CERVUS program, was a powerful tool in cattle kinship analysis when dealing with judicial dispute particularly when the dam's genotype was absent, allowing the assignments of paternity at 95% level of confidence in situations usually used by dairy and beef cattle producers in Argentine (e.g., multi-sire pasture mating).

Petrography and geochemistry of the Carapé Granitic Complex (Southeastern Uruguay) Bettucci Sanchez, Leda; Oyhantçabal, Pedro; Page, Stella; Ramos, Victor Alberto The southern sector of Uruguay was intruded by numerous granitic plutons during the Brasiliano Cycle. The granites and granodiorites of the Carapé Complex comprise a large part of the Neoproterozoic terrain exposed in southern Uruguay. Typological and age relationships show that the characteristic of the granitic rocks changed during the Brasiliano Cycle. Four groups of granitoids can be distinguished according to their emplacement. The first group corresponds to the Campanero Unit, interpreted as a pre-Brasiliano basement, which includes mainly preorogenic granites. The second group, Pan de Azúcar and related granitoids, includes synorogenic granites and granodiorites. The third granitoid group, Dos Hermanos Granite and related plutons, is classified as late- to postorogenic granites. Finally, the fourth group, consisting of the Águila Granite and related plutons, is represented by alkaline amphibole-biotite granites and are considered as post-collisional alkaline granites, which we assign to an extensional event associated with post-collisional slab-break off marking the end of the late Proterozoic Brasiliano orogenic cycle. Most of the granitic plutons in this area (2,300 km2) are relatively well exposed and have well-defined intrusive relationships with the metamorphic country-rocks. These granitic rocks are the result of successive magma pulses from similar magma chambers through the late Proterozoic to early Paleozoic times.

Variaciones geomagnéticas atribuídas a la corriente anillo ecuatorial en períodos de tormenta magnética, a partir de registros en observatorios simétricos en latitud geomagnética Van Zele, Maria Andrea Las variaciones del campo magnético terrestre registradas durante una tormenta geomagnética son la superposición de variaciones regulares y perturbaciones. Las primeras son debidas principalmente a corrientes en la alta atmósfera generadas por la acción dínamo de un sistema de vientos horizontales; las segundas a corrientes magnetosféricas e ionosféricas causadas por la transferencia de masa y energía del viento solar a la magnetosfera. Entre éstas últimas se destaca la corriente anillo ecuatorial, que circula hacia el oeste con simetría respecto del plano del ecuador geomagnético y en su vecindad; la variación geomagnética que produce ha sido tradicionalmente calculada suponiendo que tiene simetría cilíndrica alrededor del eje del dipolo geomagnético, extrapolándose por tanto que la corriente anillo ecuatorial tiene tal simetría cilíndrica. Los valores symH calculados (por minuto) por el Centro Mundial de Kyoto (Japón) pretenden expresar, con mayor definición temporal que los tradicionales índices Dst (horarios), las variaciones debidas a la corriente anillo ecuatorial. Ambos conjuntos forman sucesiones completas. En este trabajo se presenta un método que se basa en imponer una condición de simetría a la variación geomagnética que se atribuye a la corriente anillo ecuatorial: una misma variación negativa de la componente norte y variaciones opuestas de la componente vertical, a ambos lados del ecuador geomagnético. Para ello se utilizan la componente norte X y la vertical Z registradas durante tormentas geomagnéticas en pares de observatorios con latitud geomagnética conjugada y similar longitud. Los resultados permiten corroborar que la componente norte condicionada por la simetría ecuatorial depende del tiempo local (de la longitud de los observatorios), mostrando que esta variación no es independiente del ángulo acimutal alrededor del eje dipolar geomagnético (no tiene simetría cilíndrica alrededor de él). De la relación entre las componentes geomagnéticas norte y vertical que satisfacen la condición de simetría ecuatorial impuesta, se deduce que la corriente anillo ecuatorial no es la única que satisface tal condición, sino que los aportes de las variaciones debidas a las corriente de la magnetopausa, de la cola magnética, de la cuña auroral o las ionosféricas no pueden ser consideradas despreciables. El conjunto de los valores de la variación hallada con la condición de simetría respecto del plano ecuatorial no es completo.; The geomagnetic field variations recorded on the Earth during a geomagnetic storm are the superposition of both quiet and disturbed variations. The first ones are principally due to currents at the upper atmosphere generated by the dynamo action of a sys tem of horizontal wind. The second ones are due to ionospheric and magnetospheric currents caused by the mass and energy transfer of the solar wind to the magnetosphere. Among these last ones, the equatorial ring current drifts westward, with symmetry in relation with the geomagnetic equator, at 4-7 Re. It produces a geomagnetic variation that has been traditionally calculating assuming that it is symmetric around the dipole axis. The symH values calculated (each minute) by the WDC-C2 of Kyoto supposedly express, with better definition than the hourly Dst index the geomagnetic variations due to this equatorial ring current. This work presents a method based on the symmetrical condition imposed to the geomagnetic variations impute to the equatorial ring current: the same negative variation of the north X component and opposite variations of the vertical component, at both sides of the geomagnetic equator. The north X and the vertical Z components recorded during a geomagnetic storm, in pairs of observatories with conjugate geomagnetic latitude and similar longitude are used. The results verified that the conditioned X component (which is comparable with the indices) in not independent of the azimuthal angle around the dipole axis (depends on the local time). From the relation between X and Z conditioned components it is deduced that the equatorial ring current is not the only one satisfying the symmetry imposed, but variations due to the currents at the magnetopause, the magnetic tail, the auroral wedge or the ionospheric ones can not be ignored. The set of values of the conditioned variations by the equatorial symmetry is not complete.

Palinoestratigrafía y palinofacies de la Formación Lotena, Jurásico Medio de la Cuenca Neuquina, Argentina; Palynostratigraphy and palynofacies of the Lotena Formation, middle jurassic of the Neuquén basin, Argentina Martinez, Marcelo Adrian; Quattrocchio, Mirta Elena El análisis palinológico aplicado a muestras de afloramiento de la Formación Lotena (datos integrados del perfil Portada Covunco y registros previos de perfil arroyo Picún Leufú) permitió determinar 29 taxones de esporomorfos (esporas: 10 y granos de polen: 19) y 40 taxones de paleomicroplancton (prasinofíceas: 2, acritarcos: 15, dinoquistes: 23). Los resultados obtenidos a partir del análisis palinológico/palinofacial permiten sugerir un medio de depositación marino para ambas localidades, en posición distal (Portada Covunco) y proximal (arroyo Picún Leufú). Las palinofacies identificadas en el perfil Portada Covunco sugieren condiciones marinas variables desde posiciones distales (palinofacies A) hasta más proximales (palinofacies C). El registro de taxones de la Zona de Endoscriniumgaleritumreticulatum Klement, conjuntamente con la asociación de Gonyaulacystajurassica (Deflandre) Norris y Sarjeant-Scriniodiniumcrystallinum (Deflandre) Klement emend. Riding y Fensome permite sugerir que la Formación Lotena en el área de Portada Covunco, provincia de Neuquén, no sería más antigua que Caloviano Tardío.; The palynological analysis applied to outcrop samples from the Lotena Formation (integrated information from Portada Covunco section and previous data from Arroyo Picún Leufú section) allows to determine 29 sporomorph taxa (10 spores and 19 pollen grains) and 40 paleomicroplankton taxa (2 Prasinophyceae, 15 acritarchs and 23 dinocysts). A marine paleoenvironment with a variable proximal-distal trend is suggested for both sections on the basis of the palynological/palynofacial analysis. This trend varies from distal (Portada Covunco section) to proximal conditions (Arroyo Picún Leufú). Variable marine conditions from distal (palynofacies) to more proximal positions (palinofacies C) are suggested for the Portada Covunco section. The presence of the Endoscrinium galeritum reticulatum Klement Zone associated with Gonyaulacystajurassica (Deflandre) Norris and Sarjeant-Scriniodinium crystallinum (Deflandre) Klement emend. Riding and Fensome suggests an age not older than Late Callovian for the Lotena Formation at Portada Covunco, Neuquén province.

The Problem of time and gauge invariance in the quantization of cosmological models. 1. Canonical quantization methods. Shestakova, T. P.; Simeone, Claudio Mauricio The paper is the first of two parts of a work reviewing some approaches to the problem of time in quantum cosmology, which were put forward last decade, and which demonstrated their relation to the problems of reparametrization and gauge invariance of quantum gravity. In the present part we remind basic features of quantum geometrodynamics and minisuperspace cosmological models, and discuss fundamental problems of the Wheeler - DeWitt theory. Various attempts to find a solution to the problem of time are considered in the framework of the canonical approach. Possible solutions to the problem are investigated making use of minisuperspace models, that is, systems with a finite number of degrees of freedom. At the same time, in the last section of the paper we expand our consideration beyond the minisuperspace approximation and briefly review promising ideas by Brown and Kuchar, who propose that dust interacting only gravitationally can be used for time measuring, and the unitary approach by Barvinsky and collaborators. The latter approach admits both the canonical and path integral formulations and anticipates the consideration of recent developments in the path integral approach in the second part of our work.

The paper is the first of two parts of a work reviewing some approaches to the problem of time in quantum cosmology, which were put forward last decade, and which demonstrated their relation to the problems of reparametrization and gauge invariance o Shestakova, T. P.; Simeone, Claudio Mauricio The paper is the second part of the work devoted to the problem of time in quantum cosmology. Here we consider in detail two approaches within the scope of Feynman path integration scheme: The first, by Simeone and collaborators, is gauge-invariant and lies within the unitary approach to a consistent quantization of gravity. It is essentially based on the idea of deparametrization (reduction to physical degrees of freedom) as a first step before quantization. The other approach by Savchenko, Shestakova and Vereshkov is rather radical. It is an attempt to take into account peculiarities of the Universe as a system without asymptotic states that leads to the conclusion that quantum geometrodynamics constructed for such a system is, in general, a gauge-noninvariant theory. However, this theory is shown to be mathematically consistent and the problem of time is solved in this theory in a natural way.

Hormigón armado: la corrosión ataca desde adentro Vazquez, Marcela Vivian; Fernandez, Raúl El hormigón armado es un material compuesto sumamente noble; su extendido uso ha contribuido mucho al desarrollo de nuestras construcciones y, sin duda, lo seguirá haciendo. La vida útil de las estructuras construidas con este material está fuertemente condicionada por la corrosión de sus armaduras de acero. Las patologías del hormigón causadas por la corrosión generan inconvenientes económicos y sociales muy importantes, que deben ser atendidos. Debido a ello, se han encarado estudios electroquímicos que permitieron identificar los factores que determinan el inicio de la corrosión y condicionan su propagación. A partir de los conocimientos obtenidos y de las técnicas desarrolladas, es posible identificar acciones que, aplicadas desde la etapa de proyecto, contribuyen a minimizar su incidencia. Incluso, en caso de que el problema ya esté instalado, es posible realizar un diagnóstico exhaustivo que permite recomendar procedimientos de reparación para extender la vida útil de las estructuras, en óptimas condiciones de servicio. La corrosión puede mantenerse bajo control, solo debemos aprender a convivir con ella.

Vulnerabilidad global y pobreza. Consideraciones conceptuales Foschiatti, Ana Maria Hilda El análisis y la evaluación de la vulnerabilidad realizada desde distintas ópticas y a través de la consideración de temas específicos relacionados, permite detectar áreas susceptibles, diagnosticar la calidad de vida de la población en áreas espaciales localizadas y en sectores marginados, comparar el estado del equipamiento de los servicios, analizar factores socioculturales que influyen en las vulnerabilidades regionales, entre otros. De allí la importancia de su estudio conceptual para comprender la percepción de la población sobre los riesgos, analizar pautas de comportamiento, evaluar actitudes y prácticas y formular recomendaciones para implementar políticas públicas ambientales y sociales.; The analysis and evaluation of vulnerability performed from different points of view and through the consideration of specific related issues, allows the detection of susceptible areas and the diagnosis of the population's life quality in localized spatial areas and marginalized sectors, as well as the comparison of the condition of the services equipment and the analysis of social and cultural factors among others which affect regional vulnerabilities. Therefore the importance of this sort of conceptual study in order to understand the population's perception about risks, to analyze pattern of behavior, to assess attitudes and practices and to formulate recommendations to implement social and environmental public policies.

RNA fingerprinting using RAP-PCR identifies an EBAF homologue mRNA differentially expressed in rat oviduct Valdecantos, Pablo Alberto; Argañaraz, Martin Eduardo; Abate, Carlos Mauricio; Miceli, Dora Cristina As a step towards the identification of genes preferentially expressed in the oviduct during early rat embryo development, we isolated a cDNA fragment (Pr14) by using RNA arbitrarily primed PCR (RAP-PCR), being its expression restricted to oviduct and uterus; its mRNA is mainly expressed in oviduct during late luteal phase and early pregnancy. This fragment is 100% identical to a rat DNA sequence (Accession No. NW_047400) downstream the terminal exon of a Rattus norvegicus gene (Locus Link Accession No. LOC289316) similar to ebaf (endometrial bleeding-associated factor), a novel member of the Transforming Growth Factor superfamily. Northern analyses showed that this sequence hybridizes with 2.9 kb and 4.1 kb mRNAs in early pregnant rat oviducts. However, only the 4.1 kb mRNA was detected in the oviduct of non-pregnant rats, showing an increase from proestrus to diestrus. The expression of this oviduct-uterus specific mRNA suggests that the products of this gene may play a role in the oviductal reproductive process.

Axillary bud viability and dry matter production of Poa ligularis in Patagonian grasslands Souto, Cintia Paola; Becker, G. F.; Siffredi, G. L.; Busso, Carlos Alberto; Sterberg, M. Poa ligularis Nees is one of the dominant perennial grass species in Patagonian grasslands. This is the first field study which investigated the effects of defoliation frequency on its number of viable axillary buds, and subsequent dry matter production during one growing season. Experiments were arranged in a randomized complete block design. Treatments included one defoliation height (10 cm), from one to five times a year, and undefoliated controls. Bud respiratory activity was examined usingthe tetrazolium test and the vital stain Evan's blue. At the end of the growing season, plants that have been defoliated more than three times showed significatively (p<0.05) lower number of respiratory active buds than unclipped controls. A high defoliation frequency increased bud death in stem bases. Both defoliated and undefoliated plants produced more (p<0.05) axillary buds at the periphery than at their center. Defoliation treatments increased shoot weight by 13.4% on average compared with undefoliated controls, but reduced in by 10% the average number of metabolically active axillary buds. This indicates that this reduction, however, was not high enough to constrain dry matter production.It appears that Poa ligularis could tolerate moderate grazing frequency and intensity without compromising its potential regrowth capacity. Longer-term studies of the effects of defoliation on dry matter production and bud metabolic activity are needed to understand the cumulative effects of grazing of P. ligularis in natural grasslands.; Poa ligularis Nees es una de las especies de gramíneas perennes dominantes en los pastizales naturales de la Patagonia. Este es el primer estudio que investigó los efectos de la frequencia de defoliación sobre su número de yemas axilares viables, y subsiguiente producción de materia seca durante una estación de crecimiento. Los estudios se efectuaron utilizando un diseño de bloques completamente al azar. Los tratamientos incluyeron una altura de defoliación (10 cm), de una a cinco veces por año, además de controles no defoliados. La actividad respiratoria de las yemas fue examinada usando el método del tetrazolio y el colorante vital azul de Evans.Hacia el final de la estación de crecimiento, las plantas que habían sido defoliadas más de tres veces mostraron un número significativamente menor (p<0.05) de yemas con actividad respiratoria que los controles no defoliados. Una alta frecuencia de defoliación incrementó la muerte de yemas en las bases de tallos. Todas las plantas- defoliadas o no, produjeron más (p<0.05) yemas axilares en su periferia que en su centro. La defoliación incrementó 13.4% el peso de los tallos en promedio, pero redujo en 10% el número promedio de yemas axilares metabólicamente activas. Esto indica que esta reducción , sin embargo, no fue suficiente como para limitar la producción de materia seca. Parece que P. ligularis toleraría una frecuencia e intensidad moderada de pastoreo sin comprometer su capacidad potencial de rebrote. Se necesitan estudios a más largo plazo de los efectos de la defoliación en la producción de materia seca y actividad metabólica de las yemas para entender los efectos acumulativos del pastoreo de Poa ligularis en los pastizales naturales.

Progesterone treatment reduces NADPH-diaphorase/Nitric oxide synthase in Wobbler mouse motoneuron disease Gonzalez Deniselle, Maria Claudia; Garay, Laura Ines; López, Juan José; Gonzalez, Susana Laura; Mougel, Analía; Guennoun, Rachida; Schumacher, Michael; de Nicola, Alejandro Federico Previous work demonstrated that progesterone (PROG) treatment attenuates morphological, molecular and functional abnormalities in the spinal cord of the Wobbler (Wr) mouse, a genetic model of motoneuron degeneration. Wr mice show a marked up-regulation of the nitric oxide synthesizing enzyme (NOS). Since nitric oxide is a highly reactive species, it may play a role in neuropathology of Wr mice. We now studied if PROG neuroprotection involved changes of NOS activity in motoneurons and astrocytes, determined by the nicotinamide adenine dinucleotide phosphate-diaphorase (NADPHD) histochemical reaction. Two and four-month-old Wr mice at the progressive and stabilization stages of the disease, respectively, and their age-matched controls were left untreated or received a single 20-mg PROG pellet for 18 days. PROG reduced the high number of NADPHD-active motoneurons and white matter astrocytes in 2-month-old Wr mice but was unable to change the low number of NADPHD-active motoneurons in 4-month-old Wr mice or astrocytes in this age group. A large number of motoneurons in 2-month-old Wr mice showed a vacuolated phenotype, which was significantly reverted by PROG treatment. In summary, PROG treatment during the early symptomatic stage of the disease caused a significant reduction of NADPHD-active motoneurons and astrocytes and also reduced vacuolated degenerating cells, suggesting that blockade of NO synthesis and oxidative damage may contribute to steroid neuroprotection.

Effect of androgens on sexual differentiation of pituitary Gamma-Aminobutyric Acid receptor subunit GABAB expression Bianchi, Maria Silvia; Catalano, Paolo Nicolás; Bonaventura, Maria Marta; Silveyra, Patricia; Bettler, Bernhard; Libertun, Carlos; Lux, Victoria Adela R. Previous work demonstrated a sexually dimorphic ontogenic expression of gamma-aminobutyric acid receptors (GABA(B)R) in rat pituitary. As sex steroids determine sex-specific expression patterns, we now studied the effect of sex hormones on pituitary GABA(B)R expression. GABA(B)R subunits, measured by Western blot and by semi-quantitative RT-PCR and luteinizing hormone (LH), follicle-stimulating hormone (FSH) and testosterone measured by RIA were determined in two experimental designs: First experimental design: 8- and 15-day-old females (8F, 15F); 8F and 15F treated with 100 mug testosterone propionate (TP) on day 1 of life (8F100TP, 15F100TP), 8- and 15-day-old males (8M, 15M) and 8M and 15M castrated on day 1 (8MC, 15MC). Second experimental design: 8-day-old female and male animals: 8F, 8F100TP, 8F treated with 1 mug/day TP on days 1-4 (8F1TP), 8F treated with the androgen antagonist Flutamide (Flut: 2.5 mg/100 g BW of pregnant mother on days E17-E23) (8F-Flut), 8M, 8MC, 8M treated with Flut as above (8M-Flut) and 8MC-Flut. In these animals, in addition, GABA, glutamate, aspartate and taurine were measured by HPLC in hypothalami and cortex. In the first set of experiments, GABA(B1)R mRNA/protein expression was higher in 8F than in 15F, 8M or 15M. In 8F100TP, GABA(B1)R mRNA/protein decreased to male levels. TP treatment did not alter GABA(B1)R expression in 15F. There was no difference in GABA(B1)R expression between 8M and 15M and neonatal castration did not modify its expression. In the second set of experiments, TP (1 mug) or Flut did not modify GABA(B1)R in 8F, while 100 microg TP continued to decrease GABA(B1)R expression. In 8M, Flut, alone or with castration, increased GABA(B1)R mRNA/protein expression to 8F. Hypothalamic GABA content followed the same pattern as pituitary GABA(B)R expression in 8-day-old animals, suggesting a cross-regulation. With regard to hormonal levels, 100 microg, but not 1 microg TP altered gonadotropins at 8 days, although both treatments effectively androgenized females as evidenced by lack of cycling. We conclude that androgens, acting pre- and postnatally, decrease pituitary GABA(B)R subunit expression.