Amylase-Functionalized mesoporous silica thin films as robust biocatalyst platforms Bellino, Martin Gonzalo; Regazzoni, Alberto Ernesto; Soler Illia, Galo Juan de Avila Arturo A robust biocatalyst was produced by immobilization of R-amylase into mesoporous silica thin films with local order pore structure and 11 nm pore diameter, supported on glass stripes. The activity of this novel catalyst was evaluated for direct starch degradation. The catalyst films show excellent activity, and enhanced stability with respect to free enzyme at extreme conditions of pH and temperature. In addition, they can be easily separated from the reaction media and reused several times.

Circadian variations of prostaglandin E2 and F2 α release in the golden hamster retina de Zavalía, Nuria María Asunción; Fernández, Diego Carlos; Sande Casal, Pablo Horacio; Keller Sarmiento, María Inés; Golombek, Diego Andrés; Rosenstein, Ruth Estela; Silberman, Dafne Magalí Circadian variations of prostaglandin E2 and F2α release were examined in the golden hamster retina. Both parameters showed significant diurnal variations with maximal values at midnight. When hamsters were placed under constant darkness for 48 h, the differences in prostaglandin release between subjective mid-day and subjective midnight persisted. Western blot analysis showed that cyclooxygenase (COX)-1 levels were significantly higher at midnight than at mid-day, and at subjective midnight than at subjective mid-day, whereas no changes in COX-2 levels were observed among these time points. Immunohistochemical studies indicated the presence of COX-1 and COX-2 in the inner (but not outer) retina. Circadian variations of retinal prostaglandin release were also assessed in suprachiasmatic nuclei (SCN)-lesioned animals. Significant differences in retinal prostaglandin release between subjective mid-day and subjective midnight were observed in SCN-lesioned animals. These results indicate that hamster retinal prostaglandin release is regulated by a retinal circadian clock independent from the SCN. Thus, the present results suggest that the prostaglandin/COX-1 system could be a retinal clock output or part of the retinal clock mechanism.

In vitro propagation and genetic stability analysis of Evolvulus spp. Biotechnological tools for the exploration of native germplasm with ornamental potential Maritano, Patricia Fernanda; Alderete, Liliana M.; Perez de la Torre, Mariana Cecilia; Escandón, Alejandro Salvio The goal of the present work is to establish a protocol that allows the in vitro propagation of Evolvulus glomeratus and Evolvulus arizonicus. Nodal segments of both species were disinfected by the standard method (ethanol/NaClO/Tween 80) with and without the addition of an antibiotics-antifungal mixture to the Murashige and Skoog (MS) complete medium, growth regulator free. E. arizonicus did not survive to the in vitro culture starting procedure. To determine the nutritional requirements for E. glomeratus, the nodal segments were cultured on different dilutions of the MS macronutrients, being the complete MS the more adequate basal medium. Two types of explants were isolated from E. glomeratus for their in vitro propagation: nodal segments and leaves. The first ones were cultured on complete MS medium supplemented with increasing benzylaminopurine (BA) concentration from 0 to 4.4 μM, and the second ones onto the same basal medium but supplemented with the following naphthalene acetic acid and BA concentration (micromolars): 0.0, 1.3, 2.6, and 5.3 for naphthalene acetic acid and 0.0, 1.1, 2.2, and 4.4 for benzylaminopurine in all possible combinations. Under the conditions applied from the leaves, no shoot regenerations were detected. On the other hand, it was possible to recover an average close to four shoots per explant when the nodal segments were cultured on a medium supplemented with 2.2 μM benzylaminopurine. For the rooting and rustication step, in vitro and ex vitro (with Growing Mix #2 and Perlite as substrate) strategies were tested. The best result was 91. 6% efficiency of acclimated plants obtained with the ex vitro procedure using Perlite. The use of intersimple sequence repeat showed no differences among the tested regenerated plants under the applied experiment conditions. The protocol developed here is the starting point for the application of biotechnological techniques for both the massive propagation and the improvement of E. glomeratus and other related species.

Life Cycle Greenhouse Emissions of Compressed Natural Gas-Hydrogen Mixtures for Transportation in Argentina Martinez, Pablo Enrique; Dawidowski, Laura Elena; Gomez, Dario Ruben; Pasquevich, Daniel Miguel We have developed a model to assess the life cycle greenhouse emissions of compressed natural gas-hydrogen (CNG-H2) mixtures used for transportation in Argentina. The overall fuel life cycle is assessed through a well-to-wheel (WTW) analysis for different hydrogen generation and distribution options. The combustion stage in road vehicles is modeled using the COPERT IV model. Hydrogen generation options include classical steam methane reforming (SMR) and water electrolysis (WE) in central plants and distributed facilities at the refueling stations. Centralized hydrogen generation by electrolysis in nuclear plants as well as the use of solar photovoltaic and wind electricity is also considered. Hydrogen distribution options include gas pipeline and refrigerated truck transportation for liquefied hydrogen. A total number of fifteen fuel pathways are studied; in all the cases the natural gas-hydrogen mixture is made at the refueling station. The use of WE using nuclear or wind electricity appears to be less contaminant that the use of pure CNG.

Synthesis of trisaccharides containing internal galactofuranose O-linked in Trypanosoma cruzi mucins Mendoza, Veronica Maria; Kashiwagi, Gustavo Adolfo; Muchnik, Rosa; Gallo, Carola The trisaccharides β-d-Galf-(1→2)-β-d-Galf-(1→4)-d-GlcNAc (5) and β-d-Galp-(1→2)-β-d-Galf-(1→4)-d-GlcNAc (6) constitute novel structures isolated as alditols when released by reductive β-elimination from mucins of Trypanosoma cruzi (Tulahuen strain). Trisaccharides 5 and 6 were synthesized employing the aldonolactone approach. Thus, a convenient d-galactono-1,4-lactone derivative was used for the introduction of the internal galactofuranose and the trichloroacetimidate method was employed for glycosylation reactions. Due to the lack of anchimeric assistance on O-2 of the galactofuranosyl precursor, glycosylation studies were performed under different conditions. The nature of the solvent strongly determined the stereochemical course of the glycosylation reactions when the galactofuranosyl donor was substituted either by 2-O-Galp or 2-O-Galf.

Matricellular proteins and inflammatory cells: A task force to promote or defeat cancer? Llera, Andrea Sabina; Girotti, Maria Romina; Benedetti, Lorena Gabriela; Podhajcer, Osvaldo Luis In the last years it became clear that the tumor microenvironment plays a major role in neoplastic growth. Proteins secreted either by the malignant cells or by the tumor-associated stromal cells act as extracellular signal transductors, orchestrating tumor progression. Sentinel cells of the innate immune system patrol the different organs and have proven either to promote tumor growth or induce tumor suppression. In recent years, members of the matricellular family of extracellular proteins were shown to be involved in different aspects of the inflammatory response during tumor development, although in contradictory ways. In this review we discuss the evidence available up to date that relates matricellular proteins with the regulation of the inflammatory response and tumor progression.

Characterization of xenobiotic metabolizing enzymes in bovine small intestinal mucosa Virkel, Guillermo Leon; Carletti, M.; Cantiello, M.; Della Donna, L.; Gardini, G.; Girolami, F.; Nebbia, C. The intestinal mucosa plays a capital role in dictating the bioavailability of a large array of orally ingested drugs and toxicants. The activity and the expression of several xenobiotic metabolizing enzymes were measured in subcellular fractions from the duodenal mucosa of male veal calves and beef cattle displaying a functional rumen but differing in both age (about 8 months vs. 18 to 24 months) and dietary regimens (i.e., milk replacer plus hay and straw vs. corn and concentrated meal). Intestinal microsomes showed cytochrome P450 (CYP) 2B, 2C- and 3A-mediated activities and the presence of the corresponding immunorelated proteins, but no proof of CYP1A expression and/or functions could be provided. Intestinal microsomes were also active in performing reactions typically mediated by carboxylesterases (indophenylacetate hydrolysis), flavin-containing monooxygenases (methimazole S-oxidation), and uridindiphosphoglucuronyltransferases (1-naphthol glucuronidation), respectively. Cytosolic fractions displayed the glutathione S-transferase (GST)-dependent conjugation of 1-chloro-2,4-dinitrobenzene; besides, the GST-mediated conjugation of ethacrinic acid (GSTφ) or cumene hydroperoxide (GSTα) was matched by the presence of the corresponding immunorelated proteins. Conversely, despite the lack of measurable activity with 3,4-dichloronitrobenzene, a protein cross reacting with anti-rat GSTμ antibodies could be clearly detected. Although, as detected by densitometry, CYPs and GST isoenzymes tended to be more expressed in beef cattle than in veal calf preparations, there was a general poor correlation with the rate of the in vitro metabolism of the selected diagnostic probes.

Rapid and sensitive detection of Citrus Bacterial Canker by loop-mediated isothermal amplification combined with simple visual evaluation methods Rigano, Luciano Ariel; Marano, María Rosa; Castagnaro, Atilio Pedro; Morais do Amaral, Alexandre; Vojnov, Adrián Alberto Citrus Bacterial Canker (CBC) is a major, highly contagious disease of citrus plants present in many countries in Asia, Africa and America, but not in the Mediterranean area. There are three types of Citrus Bacterial Canker, named A, B, and C that have different genotypes and posses variation in host range within citrus species. The causative agent for type A CBC is Xanthomonas citri subsp. citri, while Xanthomonas fuscans subsp. aurantifolii, strain B causes type B CBC and Xanthomonas fuscans subsp. aurantifolii strain C causes CBC type C. The early and accurate identification of those bacteria is essential for the protection of the citrus industry. Detection methods based on bacterial isolation, antibodies or polymerase chain reaction (PCR) have been developed previously; however, these approaches may be time consuming, laborious and, in the case of PCR, it requires expensive laboratory equipment. Loop-mediated isothermal amplification (LAMP), which is a novel isothermal DNA amplification technique, is sensitive, specific, fast and requires no specialized laboratory equipment.

Semantically characterizing collaborative behavior in an Abstract dialogue framework Marcos, Maria Julieta; Falappa, Marcelo Alejandro; Simari, Guillermo Ricardo A fundamental requirement of collaborative dialogue formal systems is ensuring both that all the relevant information will be exposed and also irrelevancies will be avoided. The challenge is to fulfill this requirement in the context of a distributed MAS where each agent is unaware of the private knowledge of the others. We argue that it is possible to give a general treatment to this problem in terms of relevance notions, and propose a partial solution which reduces the problem to that of finding adequate potential relevance notions. Specifically, we present in this work an Abstract Dialogue Framework which provides an environment for studying the behavior of collaborative dialogue systems in terms of abstract relevance notions, together with three Collaborative Semantics each of which defines a different collaborative behavior of the dialogues under the framework. One of these semantics describes an utopian, non practical, behavior which is approximated in different ways by the other two constructive semantics. Complete examples are provided in Propositional Logic Programming. © 2010 Springer Berlin Heidelberg.

Effect of the association of reduced glutathione and ciprofloxacin on the antimicrobial activity in Staphylococcus aureus Páez, Paulina Laura; Becerra, María Cecilia; Albesa, Inés We report the effect of glutathione and the role of reactive oxygen species (ROS), assayed by a nitro blue tetrazolium reaction, on the antibacterial action of ciprofloxacin, gentamicin and chloramphenicol in Staphylococcus aureus 22 resistant to ciprofloxacin and gentamicin, and in S. aureus ATCC 29213 sensitive to the above three antibiotics. The association of glutathione with ciprofloxacin or gentamicin significantly reduced the value of the minimum inhibitory concentration (MIC) in resistant S. aureus 22, measured using the macrodilution method, with a concomitant increase of intracellular ROS and a decrease of extracellular ROS. However, glutathione did not induce modifications in MIC or ROS generated by chloramphenicol. Furthermore, in the sensitive S. aureus ATCC 29213, the association of glutathione with ciprofloxacin, gentamicin or chloramphenicol did not induce any significant variations of MIC or ROS. There was a correlation between the stimulus of intracellular ROS and the decrease of MIC caused by exogenous glutathione. According to the results obtained, it is possible to modify the sensitivity of resistant strains of S. aureus by the addition of exogenous glutathione.

Age-related differential sensitivity to cadmium in Hyalella curvispina (Amphipoda) and implications in ecotoxicity studies Garcia, M. E.; Rodrigues Capitulo, Alberto; Ferrari, Lucrecia The standardization of toxicity tests requires the selection of the most suitable test species and their developmental stages, as well as the selection of the appropriate assay matrix and the evaluation of the sensitivity of the test species to the reference toxicants. International protocols recommend the use of the amphipod Hyalella azteca from the Northern Hemisphere for sediment toxicity tests. We selected the widely distributed amphipod Hyalella curvispina, representative of pleustonic, epiphitic and zoobenthic assemblages in austral South America, as test species to be used in regional studies. Our goals were to evaluate the sensitivity of three developmental stages of H. curvispina to cadmium as a reference toxicant and to select the most suitable age and exposure time for aquatic ecotoxicity assessment. The three ages were highly susceptible to cadmium, with sensitivities: neonates > adults > juveniles. Our results validate the use of the native H. curvispina as a standard species for ecotoxicological assessment studies.

La heterogeneidad estructural vista desde tres teorías alternativas: el caso de Argentina Chena, Pablo Ignacio El presente artículo consta de dos secciones principales. En la primera de ellas se desarrolla una revisión del concepto de heterogeneidad estructural (HE) desde un marco teórico compuesto por tres teorías alternativas: la estructuralista, la neo-estructuralista y un enfoque monetario de origen regulacionista. En la segunda, estos conceptos son aplicados al estudio de la HE en Argentina, durante el período 1991-2006, ponderando la relevancia de cada una a la hora de explicar el fenómeno.

On the asymptotic behavior of general projection-pursuit estimators under the common principal components model Boente Boente, Graciela Lina; Molina, Fernanda Julieta; Sued, Raquel Mariela The common principal components model for several groups of multivariate observations assumes equal principal axes among the groups. Robust estimators can be defined replacing the sample variance by a robust dispersion measure. This paper studies the asymptotic distribution of robust projection-pursuit estimators under a common principal components model.

Solving a multicoloring problem with overlaps using integer programming Méndez Díaz, Isabel; Zabala, Paula Lorena This paper presents a new generalization of the graph multicoloring problem. We propose a Branch-and-Cut algorithm based on a new integer programming formulation. The cuts used are valid inequalities that we could identify to the polytope associated with the model. The Branch-and-Cut system includes separation heuristics for the valid inequalities, specific initial and primal heuristics, branching and pruning rules. We report on computational experience with random instances.

A novel OXA-10–like β-lactamase is present in different Enterobacteriaceae Porto, Ayelen Patricia; Ayala, Juan; Gutkind, Gabriel Osvaldo; Di Conza, José Alejandro OXA 101, a novel OXA-10 like enzyme, was found forming part of a class 1 integron located in a conjugative plasmid in three different species of Enterobacteriaceae. This β-lactamase is related to OXA-35 and OXA-56 and displays a narrow substrate hydrolysis profile.

Crystallite size-dependent phases in nanocrystalline ZrO2–Sc2O3 Abdala, Paula Macarena; Fantini, Márcia C. A.; Craievich, Aldo Felix; Lamas, Diego Germán ZrO2-10, 12 and 14 mol% Sc2O3 nanopowders were prepared by using a nitrate-lysine gel-combustion synthesis. These materials were studied by synchrotron X-ray powder diffraction (SXPD) and Raman spectroscopy after calcination at different temperatures from 650 to 1200 1C, which led to samples with different average crystallite sizes, up to about 100 nm. The results from SXPD and Raman analyses indicate that, depending on Sc2O3 content, the metastable t0 0-form of the tetragonal phase or the cubic phase are fully retained at room temperature in nanocrystalline powders, provided an average crystallite sizes lower than B30 nm. By contrast, powders with larger average crystallite sizes exhibit the stable rhombohedral, b and g, phases and do not retain or very partially retain the metastable t0 0 and cubic ones.

The overgeneralization of linear models among university students´ mathematical productions: a long-term study Esteley, Cristina Beatriz; Villarreal, Monica Ester; Alagia, Humberto Raul Over the last several years, we have been exploring and researching on a phenomenon that occurs among undergraduate students which we called extension of linear models to non-linear contexts or overgeneralization of linear models. This phenomenon appears when some students use linear representations in situations that are non-linear. In a first phase, we recognized and characterized the overgeneralization among agronomy majors while working with different kind of problems. This process let us raise some conjectures about the statement of the problems that were studied in a second phase. In a third phase we conducted some interviews in order to deep our understanding. The study allowed us to discuss: a) the robustness and broadness of the linear models as tacit models among university students, b) the emergence of a tension between unrealistic tasks posed by the teacher/researcher and the students? realistic interpretation of it, and c) some considerations about the teaching environment at university level.

Figuras para pensar la comunidad: un análisis de las revistas Eco contemporáneo y Contracultura, 1960-1971 Gatto, Ezequiel Guillermo Nuestro trabajo consiste en presentar un contrapunto entre una serie de ideas enunciadas en las páginas de dos revistas argentinas (Eco contemporáneo y Contracultura) durante los años sesenta y principios de la década siguiente alrededor de la pregunta o inquietud por la comunidad desde una perspectiva político-cultural y ciertas elaboraciones que la teoría sociológica ha dedicado en el último tiempo al problema comunitario. Generadas en el seno de prácticas contraculturales y disidentes, las ideas que circulaban en aquellas revistas pueden ser analizadas recuperando críticamente nociones tales como la de "comunidades postsocietales" de Pablo de Marinis, la de "nuevas formas de asociación" de Vargas Cetina, así como los diagnósticos y juicios de Zygmund Bauman y Luis Tapia en torno a las nuevas modalidades de agrupamientos. En ese sentido, pretendemos tensar los enunciados presentes en aquellas revistas esperando aportar, desde el análisis histórico, a la discusión sobre un tópico que, abordado desde diversas perspectivas disciplinarias, ha recobrado potencia como problema sociológico, cultural y político durante los últimos años.

La Guerrilla del Ejército Libertador: Vicisitudes políticas de una guerrilla urbana Campos, Esteban Javier; Rot, Gabriel La Guerrilla del Ejército Libertador es un eslabón perdido entre la primer etapa de la guerrilla en la Argentina, que se inicia en 1959, y el surgimiento de las organizaciones político-militares de la década de 1970. En su intento de conformar un gran frente integrado por militantes de diversas tradiciones políticas, la experiencia del GEL constituye un jalón en la estructuración de nuevos modos de intervención revolucionaria. Lo significativo de este intento será el esfuerzo por confiar en la unidad de acción contra la dictadura basada en la lucha armada, más allá de la homogeneización ideológica de sus actores y de la integridad que exige un proyecto político unitario.

Políticas de educación y su impacto sobre la superación de la pobreza infantil Cortes, Rosalia Alba; Giacometti, Claudia El documento examina el rol que han tenido en América Latina las políticas educativas y sociales sobre las capacidades de acceso, permanencia y de logros educativos de niños y niñas socialmente vulnerables, –habitantes de zonas rurales y urbanas– marginales, pobres, pertenecientes a minorías étnicas y raciales. Se analizaron las estrategias educativas de las reformas de los años noventa, que intentaron ampliar el acceso al sistema educativo en condiciones de elevados déficit fiscales y bajo margen de maniobra. La reestructuración administrativa, en particular la descentralización de los servicios educativos fueron ejes centrales de las reformas. Sin embargo éstas no fueron acompañadas por transferencias adecuadas a los gobiernos subnacionales. Se implementaron subsidios a la demanda, a través de becas escolares dirigidas a mejorar la retención, en ampliaciones de la infraestructura escolar mediante programas que no cubrían las brechas de la oferta. La expansión de la matrícula en algunos casos se hizo a expensas de la calidad de la enseñanza, sin abarcar o fortalecer las condiciones necesarias de aprendizaje en áreas, localidades y escuelas con alta incidencia de alumnado pobre. La nueva agenda educativa enfatiza el papel de la educación para alcanzar la equidad social En un clima económico de crecimiento, con consensos entre gobiernos e instituciones internacionales acerca de las obligaciones estatales, con crecientes demandas de la sociedad civil, los Estados cuentan con más medios, pero las obligaciones son mayores. Las limitaciones impuestas por la restricción fiscal fueron hasta el 2008 menos acuciantes que en la década anterior, pero resultan de peso frente al aumento de las demandas.