Coke analysis by temperature-programmed oxidation: Morphology characterization
Sanchez, Barbara Sabrina; Gross, Martin Sebastian; Dalla Costa, Bruno Oscar; Querini, Carlos Alberto
Temperature-programmed oxidation (TPO) profiles obtained using high final temperature are usually very similar in shape and it is not possible to easily distinguish among different kinetic models. Typically, statistical criteria are used to select the one that best fits the experimental TPO profile. In this work, we show that using final temperatures selected in such a way that the coke is still reacting with oxygen, relevant information can be obtained from the experimental profile. Coked naphtha reforming catalysts, obtained from an industrial reactor, are characterized by running TPO analyses using intermediate temperatures. Results clearly show that the coke reaction order changes as the coke conversion increases. When the initial coke content is approximately 5 wt% or higher, coke has a tridimensional structure that leads to a low reaction order, close to 0.2. At high conversion levels, approximately 80%, the coke reaction order starts increasing until reaching a value of 1 at conversion close to 1. This information is easily obtained by plotting the experimental coke reaction order using the data at constant temperature. In this way, it is possible to easily distinguish among different models, and to replicate the experimental results.
Conformational and vibrational analysis of methyl methanesulfonate, CH3SO2OCH3
Tuttolomondo, María Eugenia; Navarro, Amparo; Peña, Tomás; Varetti, Eduardo Lelio; Parker, Stewart F.; Ben Altabef, Aída
The molecular structure of methyl methanesulfonate, CH3SO 2OCH3, has been optimized by using methods based on density functional theory, coupled cluster, and Moller-Plesset second order perturbation theory (MP2). With regard to CH3SO2OCH 3, two populated conformations with symmetries Cs and C1 are obtained, the former being more stable than the latter. The theoretical data indicate that although both anti and gauche conformers are possible by rotation about the S-O bond, the preferred conformation is anti. The total energy as a function of the CSOC dihedral angle has been calculated using the MP2 method with the 6-31G(d) and cc-pVDZ basis sets and the hybrid functional B3LYP using 6-31G(d), 6-311G(d,p), and 6-311++G(d,p) basis sets. A natural bond orbital analysis showed that the lone pair →σ * hyperconjugative interactions favor the anti conformation. Furthermore, the infrared spectra for the liquid and solid phases, the Raman spectrum for the liquid one, and the inelastic neutron scattering spectrum of the solid phase have been recorded, and the observed bands have been assigned to the vibrational modes. The experimental vibrational data, along with calculated theoretical force constants, were used to define a scaled quantum mechanical force field for the target system that enabled us to fit the measured frequencies with a final root-mean-square deviation of 10 cm-1.
(1,1-Dichloro-2,2,2-trifluoroethylimino)sulfur dichloride, CF3CCl2N=SCl2: Vibrational spectra and quantum chemical calculations
Flores Antognini, Andrea; Cutin, Edgardo Hugo; Robles, Norma Lis; Oberhammer, Heinz
The vibrational spectra of (1,1-dichloro-2,2,2- trifluoroethylimino)sulfur dichloride, CF3CCl2N@SCl2, were recorded in the gas phase with IR spectroscopy and in the liquid state with Raman spectroscopy. Quantum chemical calculations at the HF, B3LYP (6-311+G(d) and 6-311+G(2df) basis sets) and MP2 levels of theory (6-31+G(d) and 6-311+G(df) basis sets) were performed. According to all calculations the lowest energy conformer possesses C1 symmetry with syn orientation of the SCl2 group relative to the N-C bondand near-trans orientation of the CF3 group relative to the N=S bond. Calculations predict the presence of a second stable conformer with anticlinal orientation of the SCl2 group which, however, possesses considerably higher energy and is therefore not observed in the analysis of the experimental vibrational spectra. The vibrational spectra were assigned for a single conformer in accordance with these calculations.
Alternate Cu2 and Er2 spin carriers in a carboxylate bridged chain: EPR study
Calvo, Rafael; Rapp, Raul E.; Sartoris, Rosana Patricia; Santana, Ricardo C.; Perec, Mireille
We report powder EPR measurements at 9.48 GHz and temperatures of 4 K e T e 30 K and at 33.86 GHz and T = 300 K for the polymeric compound {[Cu2Er2(L)10(H2O)4] ·3H2O}n (HL ) trans-2-butenoic acid) having alternate Cu2 and Er2 dinuclear units bridged by carboxylates along a chain. Above 70 K, when the ErIII resonance is unobservable and uncoupled from the CuII ions, the spectrum arises from the excited triplet state of antiferromagnetic Cu2 units, decreasing in intensity as T decreases, and disappearing when these units condensate into the singlet ground state. Fit of a model to the spectra at 9.48 and 33.86 GHz and 300 K gives gCu//= 2.379, gCuper = 2.065, DCu= -0.340 cm-1, and ECu ∼ 0 for the g-factors and zero field splitting parameters. From the T dependence of the intensity of the spectrum above 70 K, we obtain JCu-Cu = -336(11) cm-1 for the intradinuclear exchange interaction. Below 50 K, a spectrum attributed to Er2 units appears, narrows, and resolves as T decreases, due to the increase of the spin-lattice relaxation time T1. The spectrum at 4 K allows calculating g values g1=1.489, g2= 2.163, and g3= 5.587 and zero field splitting parameters DEr=-0.237 cm-1 and EEr = 0.020 cm-1. The results are discussed in terms of the properties of the Cu and Er ions, and the crystal structure of the compound.
Crecimiento y caracterización de películas delgadas de tio2 y ti1- xfexo2
Galvis, J.; Ramirez Jimenez, Helena; Montes, J.; Sanchez, L.; Beltran, J.; Barrero, C.; Morales, A.; Gomez, J.; Tirado Mejia, L.; Osorio, J.
Titanium dioxide (TiO2) and Fe-doped titanium dioxide (Ti1-xFexO2) thin films were grown on silicon substrates using the magnetron sputtering Rf (13.56 MHz) technique. The relevant growth parameters for the samples (pressure, power, gas mixture ratio, distance between target-substrate, among others) were found. The plasma deposition environment for the ternary films was characterized by optical emission spectroscopy in order to verify and identify the present species which were iron and titanium. The TiO2 films, deposited on silicon substrates [100], showed an amorphous phase while the ternary films showed low crystallinity. After annealing at 800 °C crystalline phases appeared, rutile in binary films and mixed in ternary films.
Differential cholinoceptor modulation of nitric oxide isoforms in experimentally-induced inflammation of dental pulp tissue
de Couto Pita, Alejandra Karina; Passafaro, D.; Ganzinelli, Sabrina Belen; Borda, Enri Santiago; Borda, Enri Santiago
Aim The aim of the study was to investigate the role of muscarinic acetylcholine receptor (mAChR) activity in the regulation of endothelial (e), neuronal (n) and inducible (i) nitric oxide synthase (NOS) activity and expression in experimentally induced inflammation of rat dental pulp tissue. Methodology Inflammation was induced by application of bacterial lipopolysaccharide (LPS) to the pulp. Extirpated pulp-tissue samples were incubated in saline solution until the various experiments were performed. Saline-treated pulp and healthy pulp tissues were used as controls. NOS activity was measured by the production of [U-14C]-citrulline from [U-14C]-arginine. Nitrite/nitrate assay was evaluated by the conversion of nitrate to nitrite in the presence of nicotinamide adenine dinucleotide phosphate. i-nos, e-nos and n-nos mRNA levels were measured using reversetranscriptase polymerase chain reaction by co-amplification of target cDNA with a single set of primers. Results Application of LPS to the pulp increased NOS activity and nitrate production (P < 0.001), generated by iNOS over-activity and expression. Pilocarpine acting on mAChRs triggered a biphasic action on NOS activity and NO accumulation. At low concentrations, pilocarpine induced a negative effect associated with a decrease in i-nos mRNA level, whilst at high concentration, it produced a positive effect associated with increased e-nos and n-nos mRNA levels. In control pulp tissue, only the positive effect of pilocarpine was observed. Conclusions Irreversible pulpitis changes mAChR conformation increasing its efficiency of coupling to transducing molecules that in turn induce activate iNOS. The capacity of pilocarpine to prevent NO accumulation and iNOS activity, by acting on mAChR mutation induced by pulpitis, might be useful therapeutically as a local treatment.
The K-theory of toric varieties
Cortiñas, Guillermo Horacio; Haesemeyer, C.; Walker, M. E.; Weibel, C.
Recent advances in computational techniques for K-theory allow us to describe the K-theory of toric varieties in terms of the K-theory of fields and simple cohomological data.
Familia y Heteronormatividad
Guerra, Luciana Analía
Desde diferentes disciplinas y perspectivas es estudiada una institución tan compleja y dinámica como la familia. Abordajes estadísticos, antropológicos, sociológicos, históricos, intentan comprender y analizar la diversidad de estructuras familiares. Incluso, estos estudios, cambiaron la noción de “familia” por el de “organizaciones familiares” para evitar caer en definiciones ahistóricas y monolíticas que pretenden instalar como “natural” una única manera de agrupamiento familiar. Sin embargo, la feminista marxista Heidi Hartmann, considera que estas investigaciones históricas, sociológicas y antropológicas, abordan las organizaciones familiares como unidades cuyos miembros comparten intereses, minimizando la conflictividad que pueda darse entre los mismos. Este punto de partida teórico no es favorable para visibilizar y comprender la situación concreta de las mujeres en el seno familiar. A partir de los aportes de los Estudios de Género y de la teoría feminista, la familia va a ser cuestionada y denunciada como ámbito de dominación masculina por excelencia dónde el mandato patriarcal de ser madre opera como eje organizador de la vida de las mujeres. Las relaciones de poder, las jerarquías por edad y sexo, la Heterosexualidad Obligatoria, la división sexual del trabajo, el trabajo doméstico no remunerado, la transmisión de valores patriarcales, la producción del binarismo sexual y la reproducción de los estereotipos de género en el proceso de socialización, son algunas de las categorías producidas por la teoría feminista para visibilizar los mecanismos de subordinación de las mujeres. Lejos de considerar a la familia como una unidad armónica con intereses comunes, esta perspectiva pone de manifiesto los conflictos y las tensiones existentes en la misma. Teniendo en cuenta los cambios económicos y políticos de los últimos tiempos y el impacto que los mismos han tenido en la estructuración de las familias, intentaré analizar, en qué medida, la familia continúa siendo o no una institución medular del sistema patriarcal, reproductora del orden heteronormativo. Con esto, nos referimos a un orden construido a partir de un sistema sexual binario y jerárquico: mujeres / femeninas / inferiores y varones / masculinos / superiores, reforzado, a su vez, por la esencialización de la sexualidad a través de la imposición de la Heterosexualidad Obligatoria. En definitiva, este sistema sexo-género como lo denominó Gayle Rubin, no sólo limita la definición de lo humano a dos categorías genéricas, varones y mujeres, sino que también disciplina el deseo sexual para que los sexos opuestos se atraigan mutuamente. Resulta de suma importancia para nuestro análisis, señalar que la heteronormatividad del patriarcado conduce a la discriminación e inferiorización tanto de toda orientación sexual disidente, como de cualquier identidad genérica que no respete la dicotomía varón-mujer –léase: travestis, transexuales, intersexuales, transgéneros, lesbianas, bisexuales, gays. Un recorrido por la realidad cotidiana de éstos colectivos humanos, nos permitirá analizar en qué sentido la “crisis de la familia” de la que tanto se habla tiene que ver con una apertura ideológica respetuosa de las múltiples maneras de vivir, construir y habitar las comunidades denominadas familias, o responde al alarmismo nostálgico de mentes conservadoras que perderían muchos privilegios si la “familia tradicional” deja de ser modelo y ejemplo de vida para las futuras generaciones.
El registro biológico humano de la costa meridional de Santa Cruz
Suby, Jorge Alejandro; Guichon, Ricardo Anibal; Zangrando, Atilio Francisco Javier
La costa patagónica constituye un sector de riesgo para el registro arqueológico, asociado a factores naturales y antrópicos. Al mismo tiempo, la conservación de las colecciones bioarqueológicas, destacándose la pérdida de restos óseos e información asociada por escasez de recursos, desconocimiento o falta de atención especializada, representa escenarios de riesgo para el registro. Una de las áreas para las cuales no se dispone hasta el momento de información bioarqueológica es la región que comprende la costa meridional de la provincia de Santa Cruz. Considerando esta ausencia de información, el objetivo de este trabajo es presentar y discutir los primeros resultados sobre restos óseos humanos hallados en la región costera próxima a la desembocadura del Rio Santa Cruz (Santa Cruz, Argentina). Los estudios incluyen el análisis de las situaciones de hallazgo y riesgo de los restos recuperados en acciones de rescate, el reconocimiento y puesta en valor de materiales depositados en el Museo Regional Carlos Borgialli (Puerto Santa Cruz, Santa Cruz, Argentina) y estudios paleopatológicos. Al mismo tiempo se informan y analizan resultados cronológicos e isotópicos. Los resultados brindan evidencias claras de la ocupación de la región costera al menos durante los últimos 2000 años, consumo de recursos predominantemente terrestres y un estilo de vida que favorece el desarrollo de lesiones articulares con escasos indicios de stress sistémico que coinciden con los resultados reportados para la región continental del estrecho de Magallanes.
Hydrosilylation of C-C multiple bonds using (Me3Si) 3SiH in water: Comparative study of the radical initiation step
Postigo, Jose Alberto; Kopsov, Sergey; Zlotsky, Simon S.; Ferreri, Carla; Chatgilialoglu, Chryssostomos
The classical radical-based hydrosilylation reaction of organic compounds bearing C-C multiple bonds is usually carried out in organic solvents and is herein presented in water with both organic solventsoluble and water-soluble substrates. Different initiation methods to accomplish the radical-induced hydrosilylation reaction of C-C multiple bonds in water with (Me 3Si)3SiH are presented. In the thermal decomposition of azo compounds, the system comprising substrate, silane, and azo-initiator (ACCN) mixed in aqueous medium at 100 °C worked well for both hydrophilic and hydrophobic substrates, with the only variation that the amphiphilic thiol HOCH2CH3SH was also needed in the case of the watersoluble compounds. Dioxygen initiation is shown to afford excellent yields of hydrosilylated products derived from substrates bearing C-C triple bonds and moderate to low yields of hydrosilylated products derived from C-C double-bonded compounds in water. Photochemical initiation in the absence of a chemical radical precursor other than the silane is also found to be a very efficient and convenient method to induce the hydrosilylation reaction of both C-C double and triple bonds of organic compounds (hydrophilic and hydrophobic substrates) with (Me3Si)3SiH in water. These three alternative radicalbased methodologies studied in water are confronted.
Feeding behavior of Adelomelon ancilla (Ligfoot, 1786): A predatory neogastropod (Gastropoda: Volutidae) in Patagonian benthic communities
Bigatti, Gregorio; Sanchez Antelo, Carlos; Miloslavich, Patricia; Penchaszadeh, Pablo Enrique
Adelomelon ancilla, a volutid commonly found in shallow water in northern Patagonia, is a top predator in the benthic communities of this region. This species presents an anemone (Antholoba achates) epibiosis that may protect it from predators. Adelomelon ancilla captures prey by tightly engulfing it with the foot, and ingests them, generally alive, after narcotizing their muscles. A narcotizing substance, produced by the accessory salivary glands, is released through the proboscis into the prey while the latter is tightly enveloped within the foot, allowing for prey narcotization. In this space, water is not abundant and, therefore, the salivary secretion reaches a high concentration, with a pH of around 10. Analysis of prey obtained in situ indicated that A. ancilla mainly consumes bivalves (88.9%), gastropods (9.5%) and, rarely, sea urchins (1.6%). Ingestion of the prey usually occurs while the predator is buried in the substrate, and may last for several hours. The anatomy of the alimentary system and the pH of various organs involved in prey capture and digestion are presented along with a comparison with feeding mechanisms among other species of Volutidae.
Influence of hydraulic conditions over dunes on the distribution of the benthic macroinvertebrates in a large sand bed river
Amsler, Mario Luis; Blettler, Martin Cesar Maria; Ezcurra, Ines Delia
This study aims to relate the flow structure over mobile dunes recorded on the channel bed of the Paraná River (Argentina) with the spatial distribution of the benthic macroinvertebrates. The following main conclusions have been obtained: (1) the dunes found in the active channel could be considered as hydraulic biotopes at a mesohabitat scale: the bed forms in the thalweg region are subjected to higher shear stresses with low benthic densities; (2) differences in benthic densities were also recorded at within-dunes microhabitat scales: the largest densities were found in the dune troughs where small bed shear stresses occur and minimum densities on the low stoss side of dunes where turbulent agitation near the bottom strongly disturb the bed particles; (3) superimposed dunes on larger dunes may be considered as another microhabitat of still smaller dimensions. Summarizing, multiscale approaches are needed if a comprehensive understanding linking hydrodynamics and morphodynamics processes with benthic ecology is intended.
Distribución y conservación del ciervo de los pantanos (Blastocerus dichotomus) en la provincia de Santa Fe, Argentina.Resultados Preliminares
Eberhardt, María Ayelen Teresita; Antoniazzi, Leandro Raúl; Lartigau, Bernardo Lartigau; Herrera, Pablo; D'Alessio, Santiago
El ciervo de los pantanos (Blastocerus dichotomus) es el mayor cérvido autóctono sudamericano (D`Alessio y col. 2001). Esta especie se encuentra actualmente presente en una serie de núcleos poblacionales inconexos. Los registros históricos del ciervo de los pantanos en la provincia de Santa Fe hacen referencia a su abundancia pasada en las islas del Paraná y territorios aledaños (Beck-Bernard, 2001; Furlong, 1938; Cabrera y Yepes, 1940), aunque en la actualidad parece haber desaparecido en la mayor parte del valle del río Paraná (Pautasso, 2008). Son escasos los datos acerca de la distribución y el estado de conservación de la especie en la provincia de Santa Fe. El presente trabajo se desarrolló en el marco del proyecto de un Plan Nacional para la Conservación del Ciervo de los Pantanos impulsado por la Asociación para la Conservación de la Naturaleza (ACEN), con el aval y apoyo de la Asociación Biológica de Santa Fe (BioS) y de la Dirección de Manejo Sustentable de Fauna y Flora, Subsecretaría de Recursos Naturales de la Secretaría de Medio Ambiente de la provincia de Santa Fe (Ministerio de Aguas, Servicios Públicos y Medio Ambiente). El objetivo fue determinar la distribución de esta especie en la provincia de Santa Fe, generando información actualizada y precisa sobre su estado de conservación. Además a través del trabajo de campo se apuntó, en la medida de lo posible, a sumar información respecto a otras especies de interés de conservación y con bajo nivel de conocimiento para la zona.El estudio se restringió al sector nordeste de la provincia de Santa Fe (este del departamento General Obligado y nordeste de San Javier), incluyendo el área donde se concentran los registros recientes para el ciervo de los pantanos (Pautasso, 2008; Giraudo y Arzamendia, 2008), extendiéndose hacia el sur hasta la localidad de Romang, con el fin de cubrir áreas potenciales de presencia de la especie.El área de estudio se dividió en 10 cuadrículas de 30 km de lado. Se utilizó el método de encuestas para determinar ?presencia / ausencia? de la especie. Se estableció un mínimo de cuatro entrevistas por cuadrícula, una por cada cuadrante de 15 km de lado.El muestreo se realizó siempre en territorio santafesino y en los lugares más accesibles. Las entrevistas fueron de tipo informal (Dietrich, 1995), y se realizaron a referentes locales, guardafaunas, pescadores y puesteros de establecimientos rura-les que realizan actividades en la zona de islas y campos aledaños y que se consideraron informantes válidos.Se realizaron 48 entrevistas a lo largo del área de estudio.En el 28,26% de las encuestas totales se obtuvieron datos positivos para la especie: observaciones directas o individuos cazados en los últimos 10 años. Los mismos corresponden a las cuadrículas uno, dos, tres y cinco; comprendidas entre Puerto Ocampo (S28º 31´ 28.0´´ O 59º 07´ 36.8´´) y el Paralelo 28º. El índice de presencia, en dichas cuadrículas, estuvo entre 0,17 y 1 (Tabla 1). En el resto del área (20.59 % de las entrevistas restantes) se obtuvieron datos históricos de su presencia, entre 50 y 100 años atrás.En general, los lugareños coinciden en que los avistajes de los ciervos son durante las crecientes o después de ellas, cuando estos se ven obligados a desplazarse a lugares más elevados, por los niveles hidrométricos del río.A partir del análisis de las entrevistas realizadas a los pobladores locales y de la bibliografía consultada, se fue recogiendo elementos e información que permitieron conformar una idea de cuáles son las amenazas directas y potenciales que posee el ciervo de los pantanos en la provincia de Santa Fe. Estos resultados, por lo tanto, ratifican la presencia del ciervo de los pantanos en la región noreste de la provincia de Santa Fe. Los registros obtenidos en las localidades de Las Toscas y Florencia permiten hipotetizar una posible conexión con poblaciones recientemente reportadas en Chaco y Corrientes. Por lo tanto, los ejemplares observados en la provincia de Santa Fe, podrían representar un núcleo poblacional relictual en contacto con dichas poblaciones o bien, ser un sumidero de las mismas. Las principales amenazas detectadas son, la caza ilegal, el aumento de la actividad ganadera en las zonas (incremento de presencia humana y del contacto de la especie con el ganado) y la falta de conocimiento de la especie por parte de la comunidad, ya que, en general los encuestados no reconocen al ciervo de los pantanos como especie local. Debido a la situación crítica que se reporta para la especie en la zona, la información generada hasta el momento sobre la realidad del ciervo de los pantanos en el nordeste santafesino, junto a la de las provincias de la región, debe ser utilizada rápidamente para diseñar estrategias de conservación a nivel provincial y nacional.
Hacer el desierto: Ensayo y fotografía en la percepción del otro durante la Campaña al Desierto
Mailhe, Alejandra Marta
¿Cómo dialogan, para aprehender al "otro", el ensayo y la fotografía producidos entre la "campaña" y los años inmediatamente posteriores a la misma? ¿Qué figuraciones de la identidad propia (letrada, militar, científica) recortan por conüérgencia y/o por contraste? ¿Mediante qué operaciones arbitrarias se aísla, resignificaylo invisibiliza un corpus de prácticas y cuerpos, para forjar al "otro" como objeto de conocimiento y representación? lndagaremos en torno a estos interrogantes a partir del análisis estético e ideológico de Viaie al país de los araucanos (1881) de Estanislao Zeballos y de los álbumes fotográficos producidos porAntonio Pozzo y por Carlos Encina y Evaristo Morenol. Estos universos discursivos traman parte del sentido histórico de las campañas represivas por medio de las cuales se consolidan las fronteras de los modernos estados nacionales. Abordando desde diversas perspectivas los corpus de imágenes producidos por Pozzo y Encina-Moreno, varios críticos (entre otros Vezub, 2002; Tell, 2007 y Ferguson-Alimonda, 2008) han analizado el modo en que la fotografía ligada a la "campaña" subraya la espectacularidad de la irrupción de la civilización sobre el escenario "vacío" del territorio. En este sentido, nos interesa especialmente retontbr sus análisis, indagando comparativamente ensayo y fotografía desde un doble punto de vista: estético e ideológico.; How do the essay and the photography produced between the "Campaña al Desierto" and subsequent years establish a dialogue in order to conceive of the "othe/'? What images of identity in its proper sense (erudite, military, scientific) do they build? How do they isolate, redefine and/or hide a corpus of practices and bodies to define the "othed'as an object of knowledge and representation? We investigate these issues starting with the aesthetic and ideological analysis of Viaje al país de /os ararucanos (1881) by Estalislao Zeballos followed by the photographic albums produced by Antonio Pozzo and Carlos Encina and Evaristo Moreno. These discourses generate part of the historical sense of the repressive campaigns that consolidated the borders of national modern states. In general, Zeballos' essay and the albums celebrate the advance of civilization. They emphasize certain facts and hide others, producing an interpretation that is far from being the "testimony of a historical truth". This vision relates more to the ideology of the subject of enunciation himself than to alterity as such.
FSH and bFGF stimulate the production of glutathione in cultured rat sertoli cells
Gualtieri, Ariel Félix; Mazzone, Graciela Luján; Rey, Rodolfo Alberto; Schteingart, Helena Fedora
Migration of developing germ cells from the basal to the adluminal compartment of the seminiferous epithelium requires extensive tissue restructuring, resulting in the production of reactive oxygen species. Sertoli cells are involved in this process. Glutathione (GSH), produced by Sertoli cells, has an essential role in cell protection against oxidative stress. Intracellular GSH content is maintained by de novo synthesis, involving glutamate-cysteine ligase catalytic (GCLC) and modulatory (GCLM) subunits, and by recycling from oxidized GSH, catalysed by glutathione reductase (GR). To assess whether follicle-stimulating hormone (FSH) and basic fibroblast growth factor (bFGF) modulate GSH production in Sertoli cells by regulating the expression of GCLC, GCLM and/or GR, we performed in vitro studies using rat Sertoli cells in primary culture. FSH and bFGF stimulation increased Sertoli cell GSH levels after 24 h incubation. The simultaneous addition of FSH and bFGF did not produce any further effect. GCLM expression was upregulated by FSH and bFGF 6 h. At 24 h, only the FSH-mediated effect was still observed. FSH and bFGF also upregulated GR expression. In conclusion, our results show that FSH and bFGF increase GSH levels in Sertoli cells through stimulation of the de novo synthesis and recycling by upregulating GCLM and GR expression respectively. Therefore, protection of germ cells against oxidative stress seems to be regulated by hormones and germ cell-released growth factors capable of influencing the production of Sertoli cell GSH.
DFT broken-symmetry exchange couplings calculation in a 1D chain of bridged iron basic carboxylates
Alborés, Pablo; Rentschler, Eva
DFT broken-symmetry calculations at the B3LYP level were carried out to evaluate the exchange coupling constants defined by the Heisenberg-Dirac-van Vleck spin Hamiltonian (HDvV), Ĥ = -2JŜaŜb, in a 1D chain of iron basic carboxylate cores [Fe3O(Piv)6(H2O)] bridged by dicyanamide, and two related trinuclear Fe3O moieties. The chain complex was modeled as two Fe3O units that preserve all features of the repetitive unit in the infinite real system. All geometries were taken from the crystallographic data previously reported. The obtained calculated values for the J constants are in good agreement with experimental results. The weak anti-ferromagnetic inter-Fe3O core interaction along the chain is also reasonably accounted by the calculations. This methodology appears as a useful tool in the theoretical evaluation of exchange coupling constants in 1D systems.
Stromal cell expression of caveolin-1 predicts outcome in breast cancer
Sloan, Erica K.; Ciocca, Daniel Ramon; Pouliot, Normand; Natoli, Anthony; Restall, Christina; Henderson, Michael A.; Fanelli, Mariel Andrea; Cuello Carrión, Fernando Darío; Gago, Francisco E.; Anderson, Robin L.
Caveolin-1 has been linked to tumor progression and clinical outcome in breast cancer, but a clear resolution of its role as a prognostic marker is lacking. We assessed caveolin-1 levels in normal breast tissue and two breast cancer cohorts for which outcome data were available. We found that caveolin-1 was not expressed in normal breast luminal epithelium but was present in the epithelial compartment of some tumors. We found no association between caveolin-1 expression in the epithelial compartment and clinical outcome. However, high levels of caveolin-1 in the stromal tissue surrounding the tumor, rather than within tumor cells, associated strongly with reduced metastasis and improved survival (P < 0.0001). The onset of mammary tumors driven by Her2/neu overexpression was accelerated in mice lacking caveolin-1, thereby supporting the observation that the presence of caveolin-1 in the tumor microenvironment modulates tumor development. These studies suggest that stromal caveolin-1 expression may be a potential therapeutic target and a valuable prognostic indicator of breast cancer progression.
Las expectativas de los débiles. Protesta obrera y política en Tucumán, durante el verano de 1932
Fernandez de Ullivarri, Maria
Este trabajo intenta analizar los procesos de lucha obrera en la provincia de Tucumán, al norte de la Argentina, durante los primeros meses del año 1932 y sus vínculos con los sucesos políticos provinciales. Para ello nos detendremos en una coyuntura de protesta obrera en un momento de crisis política, social y económica, donde la represión fue un componente importante de las relaciones entre el Estado y la sociedad. De esta forma, una huelga violenta en 1932, el contexto político e institucional particular en el que se inscribió, los usos que de ella hicieron los políticos y los sentidos otorgados a ella por los trabajadores pretenden ser el nudo central de este artículo.; Abstract:
This paper attempts to analyze the processes of labor struggle in the province
of Tucuman, northern Argentina, during the first months of 1932 and its links
with the local political events. To do this we’ll examine a period of protest at
a time of political, social and economic crisis, where repression was an
important component of relations between state and society. In this way, a
violent strike in 1932, the particular political and institutional context in which
it was entered, the uses made of it by politicians and the senses given to it by
workers are the main topics of this article
Carbohydrate-binding proteins: dissecting ligand structures through solvent environment occupancy
Gauto, Diego Fernando; Di Lella, Santiago; Guardia, Carlos Manuel Alberto; Estrin, Dario Ariel; Marti, Marcelo Adrian
Formation of protein ligand complexes is a fundamental phenomenon in biochemistry. During the process, significant solvent reorganization is produced along the contact surface and many water molecules strongly bound to the protein's ligand binding site must be displaced. Both the thermodynamics and kinetics of this process are complex and a clear understanding at the microscopic level has been not achieved so far. Special attention has been paid to the structure of water molecules on carbohydrate recognition sites of various proteins, and many studies support the idea that displacement of these water molecules should have a crucial effect on the binding free energy. Molecular dynamics (MD) simulations in explicit water solvent is a very promising approach for this type of studies. Using MD simulations combined with statistical mechanics analysis, thermodynamic properties of these water molecules can be computed and analyzed in a comparative view. Using this idea, we developed a set of analysis tools to link solvation with ligand binding in a key carbohydrate binding protein, human galectin-1 (hGal-1). Specifically, we defined water sites (WS) in terms of the thermodynamic properties of water molecules strongly bound to protein surfaces. In the present work, we selected a group of proteins whose ligand bound complexes have been already structurally characterized in order to extend the analysis of the role of the surface associated water molecules in the ligand binding and recognition process. The selected proteins are concanavalin-A (Con-A), galectin-3 (Gal-3), cyclophilin-A (Cyp-A), and two modules CBM40 and CBM32 of the multimodular bacterial sialidase. Our results show that the probability of finding water molecules inside the WS, p(V), with respect to the bulk density is directly correlated to the likeliness of finding an hydroxyl group of the ligand in the protein-ligand complex. This information can be used to analyze in detail the solvation structure of the carbohydrate recognition domain (CRD) and its relation to the possible protein ligand complexes and suggests addition of OH-containing functional groups to displace water from high p(V) WS to enhance drugs, specially glycomimetic-drugs, protein affinity, and/or specificity.
