The effect of aluminium alloy secondary phases on aniline-based silane Trueba, Mónica; Trasatti, Stefano P.; Flamini, Daniel Omar Commercial wrought Al alloys with high content of intermetallic phases, namely, AA5083-H111, AA2024-T3 and AA7075-T6, were treated with N-(3-trimethoxysilylpropyl) aniline (AnSi) by a simple procedure. Characterization studies and corrosion experiments indicate that the hybrid film protection capacity is related in a complex way to the macromolecular network structure linked to the Al substrate composition. Nevertheless, barrier protection enhanced by a buffer effect and galvanic coupling, as aided by aniline units within the hybrid film, is indicated mostly. Results overall demonstrate synergistic effect against Al alloy corrosion by combining at a molecular level monomers of conducting polymers and silane functionalities.

Hedonic games related to many-to-one matching problems Cesco, Juan Carlos We consider the existence problem of stable matchings in many-to-one matching problems. Unlike other approaches which use algorithmic techniques to give necessary and sufficient conditions, we adopt a game theoretic point of view. We first associate, with each many-to-one matching problem, a hedonic game to take advantage of recent results guaranteeing the existence of core-partitions for that class of games, to build up our conditions. The main result states that a many-to-one matching problem, with no restrictions on individual preferences, has stable* matchings if and only if a related hedonic game is pivotally balanced. In the case that the preferences in the matching problem are substitutable, the notions of stability and stability* coincide. © 2011 Springer-Verlag.

Differential participation of phospholipase A2 isoforms during iron-induced retinal toxicity. Implications for age-related macular degeneration Rodriguez Diez, Guadalupe; Uranga, Romina Maria; Mateos, Melina Valeria; Giusto, Norma Maria; Salvador, Gabriela Alejandra Both elevated iron concentrations and the resulting oxidative stress condition are common signs in retinas of patients with age-related macular degeneration (AMD). The role of phospholipase A2 (PLA2) during iron-induced retinal toxicity was investigated. To this end, isolated retinas were exposed to increasing Fe2+ concentrations (25, 200 or 800 μM) or to the vehicle, and lipid peroxidation levels, mitochondrial function, and the activities of cytosolic PLA2 (cPLA2) and calcium-independent PLA2 (iPLA2) were studied. Incubation with Fe2+ led to a time- and concentration-dependent increase in retinal lipid peroxidation levels whereas retinal cell viability was only affected after 60 min of oxidative injury. A differential release of arachidonic acid (AA) and palmitic acid (PAL) catalyzed by cPLA2 and iPLA 2 activities, respectively, was also observed in microsomal and cytosolic fractions obtained from retinas incubated with iron. AA release diminished as the association of cyclooxigenase-2 increased in microsomes from retinas exposed to iron. Retinal lipid peroxidation and cell viability were also analyzed in the presence of cPLA2 inhibitor, arachidonoyl trifluoromethyl ketone (ATK), and in the presence of iPLA2 inhibitor, bromoenol lactone (BEL). ATK decreased lipid peroxidation levels and also ERK1/2 activation without affecting cell viability. BEL showed the opposite effect on lipid peroxidation. Our results demonstrate that iPLA2 and cPLA2 are differentially regulated and that they selectively participate in retinal signaling in an experimental model resembling AMD.

“Atravesando fronteras”: Prácticas compartidas e identidades sociales negociadas durante el tardío prehispánico. Una discusión desde la alfarería ordinaria del valle del Bolsón (Belén, Catamarca); “Traversing frontiers”: shared practices and negotiated social identities in the late prehispanic. A discussion on common pottery from the valle del Bolsón (Belén, Catamarca) Puente, Veronica La alfarería ordinaria, del mismo modo que cualquier otro ítem de la cultura material, tiene un papel activo en la producción y reproducción de relaciones y significaciones sociales. El propósito de este trabajo es contribuir en el estudio de las prácticas sociales de producción y consumo de estos objetos como instancias que permiten debatir la construcción de identidades sociales en procesos de interacción macrorregional durante el tardío prehispánico en el área valliserrana del NOA. Para ello se presentan y sintetizan las características estéticas visuales –morfología, tratamiento de superficie, iconografía– y petrográficas de los conjuntos cerámicos ordinarios recuperados en dos asentamientos ubicados en el valle del Bolsón (Belén, Catamarca). Estos resultados son puestos en relación con los obtenidos en regiones vecinas, y a partir de ellos planteo la existencia de patrones estéticos y tecnológicos compartidos que atraviesan las fronteras regionales y también estilísticas planteadas tradicionalmente para el área y período cronológico mencionado.; Common pottery, like any other item of material culture, plays an active role in the production and reproduction of social relations and meanings. This paper contributes to the study of the social practices of production and consumption of these objects as instances that allow us to discuss the construction of social identities in macro-regional interaction processes during the late Prehispanic in the Valliserrana region of Northwestern Argentina. Thus, we present and synthesize the visual aesthetic characteristics -morphology, surface treatment, iconography- and petrography of the ceramic assemblages from two settlements in the Bolsón valley (Belén, Catamarca). We compare these results with those of neighboring regions and posit the existence of shared aesthetic and technological models that cross the regional and stylistic boundaries traditionally applied to this area and for this chronological period.

Skeletal development and adult osteology of Hypsiboas pulchellus (Anura: Hylidae) Hoyos, Julio M.; Sánchez-Villagra, Marcelo; Carlini, Alfredo Armando; Mitgutsch, Christian Osteological and skeletal characters have long been proven to be particularlyinformative in taxonomic and systematic research. Furthermore, ossification sequencesare assumed to be a potential tool to investigate developmental states and developmentalmodes of fossil and extant skeletal specimens. Herein, we provide a detailed accounton adult osteology and skeletogenesis in the Montevideo treefrog, Hypsiboas pulchellus(Anura: Hylidae) based on evaluation of a series of cleared and stained specimens.A consensus sequence of ossification, i.e., the order of appearance of mineralized elementsuntil early metamorphosis could be determined as (parasphenoid, presacral vertebraeI-VII, frontoparietal, exoccipital) ? transverse processes of presacral vertebraeI-VIII ? sacral vertebra ? (humerus, radioulna, ilium, femur, tibiofibula, scapula) ?(cleithrum, clavicle, coracoids, metacarpals, tarsals, metatarsals, phalanges, hypochord)? (prootic, angulosplenial, dentary, maxilla, premaxilla, squamosal). Comparing thestate of mineralized elements in individual specimens, a number of skeletal elements,including the exoccipital, frontoparietal, parasphenoid and prootic, as well as elementsof the shoulder and pelvic girdles, and the phalanges, were found to vary intraspecificallyregarding the relative time of their ossification within the ossification sequence.

Erythrolamprus reginae (Linnaeus, 1758). Culebra acuática de panza anaranjada Arzamendia, Vanesa; Giraudo, Alejandro Raul; Bellini, Gisela Paola Especie que presenta una amplia distribución tropical en áreas cisandinas de Sudamérica desde Colombia hasta el extremo norte de Argentina, también Trinidad y Tobago (Dixon, 1983). En Argentina presenta su límite de distribución meridional, siendo escasa en la mayoría de las localidades conocidas (con excepción del Parque Nacional Iguazú, Giraudo et al., 2009) en las provincias de Misiones, Salta, Jujuy (Parque Nacional Calilegua) y en el área de inundación de la presa de Yacyretá, en zonas limítrofes entre Paraguay y Corrientes (Álvarez et al., 1995; Giraudo, 2001; Giraudo y Scrocchi, 2002; Scrocchi et al., 2006; Arzamendia y Giraudo, obs. pers.). Habita en las ecorregiones Paranaense y de las Yungas, ambos ecosistemas con elevadas tasas de deforestación en Argentina, siendo además especialista en el uso del substrato (acuática), y en el uso de hábitat (arroyos y ríos rodeados con selvas y bosques fluviales). La población del área de Yacyretá ha sido fuertemente impactada por la represa que provocó la pérdida de su hábitat, y este grave impacto a los ecosistemas acuáticos y selvas del río Uruguay, se repetirá de construirse la represa de Garabí, donde la especie alcanza sus latitudes más meridionales en Argentina (Arzamendia y Giraudo, 2009). Las selvas en galería del Uruguay están modificadas por usos turísticos intensivos, represas (Salto Grande), forestaciones de exóticas, a pesar de ser un importante corredor biogeográfico de especies tropicales (Giraudo y Arzamendia, 2004). Adicionalmente, es afectada por atropellamientos en las rutas y eliminación por parte de las personas (Giraudo et al., 2009).

Topological synthesis of planar metamorphic mechanisms for low-voltage circuit breakers Pucheta, Martín Alejo; Butti, Agostino; Tamellini, Valerio; Cardona, Alberto; Ghezzi. Luca This article presents a systematic graph theory-based method for the topological synthesis of planar metamorphic mechanisms including metamorphic transformations of links and changes in the degrees-of-freedom. The parts to move, with input and output motion defined, and the topological design space, are represented by graphs of simple-jointed mechanisms. The topological requirements involving link transformations are expressed in terms of subgraphs with a given degrees-of-freedom containing prescribed input and output parts. The algorithm executes two subgraph searches inside atlases of mechanisms with different degrees-of-freedom. An application to the design of a family of low-voltage circuit-breaker mechanisms is shown.

Is foliar flammability of woody species related to time since fire and herbivory in northwest Patagonia, Argentina? Blackhall, Melisa; Raffaele, Estela; Veblen, Thomas Question: In northwest Patagonia burning of fire-resistant forests creates a community-level positive feedback towards increased fire occurrence because of successional replacement by fire-prone shrublands. We hypothesize that variability in plant traits related to time since last fire and to herbivory by cattle may affect foliar flammability, thus providing a flammability-promoting mechanism operating at the level of individual plants. We examine how plant foliar traits affecting flammability vary across species and at sites recovering from recent fires (<15 yr) vs sites not affected by fire for > 50 yr, both in the presence and absence of cattle. Location: Nahuel Huapi National Park, northwest Patagonia, Argentina. Methods: We measured four foliar traits expected to affect flammability: leaf moisture, leaf size, specific leaf area and leaf strength, and conducted tests of ignitability (time to ignition and duration of combustion) on leaves of six common tall shrub and small tree species: non-palatable Lomatia hirsuta and Diostea juncea, moderately palatable Nothofagus antarctica and Schinus patagonicus and highly palatable Maytenus boaria and Ribes magellanicum. We used ANOVA and PCA to examine potential relationships among species flammability traits, time since fire and presence or absence of cattle. Results: At plant level, variability in flammability-related foliar properties is strongly and consistently related to time since last fire, whereas effects of cattle are more variable across species and treatments. In comparison with unburned forests, the dominant woody species at shrubland sites showed reduced leaf moisture, leaf size and specific leaf area. Under pressure from cattle, N. antarctica, one of the most important woody species in these shrublands, showed changes in some foliar traits expected to enhance flammability (e.g. shorter time to ignition) but overall the influence of cattle on flammability was not consistent. Conclusions: The current study demonstrates that plant foliar traits vary between recently burned and unburned sites, and that these variations may enhance foliar flammability in shrubland communities. We hypothesize that variability in plant traits related to time since last fire and to herbivory by cattle may affect foliar flammability, thus providing a flammability-promoting mechanism operating at the level of individual plants. In northwestern Patagonia, Argentina, plant foliar traits vary between recently burned and unburned sites, and these variations may enhance foliar flammability in shrubland communities.

Tamaño y estimación de la masa corporal en Procariama simplex Rovereto, 1914 (Aves: Phorusrhacidae: Psilopterinae); Size and body mass in Procariama simplex Rovereto, 1914 (Aves: Phorusrhacidae: Psilopterinae) Vezzosi, Raúl Ignacio La masa corporal de ejemplares de aves fósiles puede ser estimada mediante comparaciones con las formas actuales, teniendo en cuenta que las medidas del fémur, el tibiotarso y el tarsometatarso son indicadoras del peso del animal. Estos huesos representarían una relación directa con la masa corporal, ya que proveen en distinto grado el sostén del cuerpo. En esta contribución, se calcula la masa corporal de ejemplares asignados a Procariama simplex Rovereto provenientes del Mioceno superior de Argentina, utilizando dos estimativos diferentes. El primero asume que existe similitud geométrica entre un ave fósil, cuya masa se pretende estimar, y una forma viviente análoga como Cariama cristata Linnaeus. El segundo modelo, más adecuado para su aplicación en aves, considera la influencia del tamaño o de la masa corporal sobre la forma y la función del esqueleto. Se basa en considerar la relación logarítmica entre la masa corporal y la circunferencia mínima de la diáfisis de los elementos del miembro posterior, implicados más específicamente en el sostén de un ave. Ambos modelos, aplicados sobre el material de estudio, reflejan valores estimados entre 10 y 13 kg para Procariama simplex, superando estimaciones previas efectuadas en este taxón, asemejándose en proporciones de tamaño (masa) a un ñandú patagónico de la especie Pterocnemia pennata d?Orbigny. Si bien esta especie de Rheidae no se encuentra emparentada filogenéticamente con los Phorusrhacidae, comparten el morfotipo de poseer miembros posteriores largos y aptos para la carrera.; Body mass of fossil birds can be estimated using comparisons with extant birds, taking into account that the measures of hindlimbs are indicators of body weight. Hindlimb bones (femur, tibiotarsus, and tarsometatarsus) would represent a direct relationship with body mass, because they provide in different degrees the support of the body. In this contribution, the body mass of fossil specimens of Procariama simplex Rovereto from the Miocene of Argentina is calculated using two different estimates. The first model assumes that there is geometric similarity between fossil and extant analogous birds, in this case between Procariama simplex and its analogous Cariama cristata Linnaeus. The second model, more used in birds, considers the influence of the size or body mass on the form and function of the skeleton. It considers the logarithmic relationship between body mass and the minimum circumference of the shaft of the hindlimb elements involved in the support of a bird. Both models estimate values between 10 and 13 kg for Procariama simplex, higher than previous estimates. These values resemble in size (mass) to that of a Patagonian rhea Pterocnemia pennata d´Orbigny. Although this Rheidae is not related phylogenetically to Phorusrhacidae, they share the same morphotype of having long hindlimbs, suitable for running.

A high oxfendazole dose to control porcine cysticercosis: Pharmacokinetics and tissue residue profiles Moreno Torrejon, Laura; Lopez Urbina, L.; Farias, Cristina Elena; Domingue, G.; Donadeu, M.; Dungu, B.; García, H. H.; Gomez Puerta, L. A.; Lanusse, Carlos Edmundo; González, A. E. Oxfendazole (OFZ) is efficacious for porcine cysticercosis at 30mg/kg. OFZ is not registered to be used at this dose. The assessment of the OFZ and metabolites [(fenbendazole sulphone (FBZSO2), fenbendazole (FBZ)] plasma pharmacokinetic and tissue residue profiles after its oral administration to pigs and the withdrawal period for human consumption were reported. Forty-eight pigs allocated into two groups received OFZ (30mg/kg) orally as a commercial (CF) or as experimental formulation (SMF). Samples (blood, muscle, liver, kidney and fat) were collected over 30days post-treatment and analyzed by HPLC. OFZ was the main compound recovered in plasma, followed by FBZSO2 and low FBZ concentrations. OFZ AUC0-LOQ (209.9±33.9μg·h/ml) and Cmax (5.40±0.65μg/ml) parameters for the CF tended to be higher than those for the SMF (AUC0-LOQ: 159.4±18.3μgh/ml, Cmax: 3.80±0.35μg/ml). The highest total residue (OFZ+FBZSO2+FBZ) concentrations were quantified in liver, followed by kidney, muscle and fat tissue. FBZSO2 residue levels were the highest found in muscle (0.68±0.39μg/g) and fat (0.69±0.39μg/g). In liver and kidney the highest residues corresponded to FBZ (5.29±4.36μg/g) and OFZ (2.86±0.75μg/g), respectively. A withdrawal time of 17days post-treatment was established before tissues are delivered for human consumption.

Adaptive finite element method for shape optimization Morin, Pedro; Nochetto, Ricardo Horacio; Pauletti, Miguel Sebastian; Verani, Marco We examine shape optimization problems in the context of inexact sequential quadratic programming. Inexactness is a consequence of using adaptive finite element methods (AFEM) to approximate the state and adjoint equations (via the dual weighted residual method), update the boundary, and compute the geometric functional. We present a novel algorithm that equidistributes the errors due to shape optimization and discretization, thereby leading to coarse resolution in the early stages and fine resolution upon convergence, and thus optimizing the computational effort. We discuss the ability of the algorithm to detect whether or not geometric singularities such as corners are genuine to the problem or simply due to lack of resolution - a new paradigm in adaptivity.

Viscosity of supercooled aqueous glycerol solutions, validity of the Stokes-Einstein relationship, and implications for cryopreservation Trejo González, José Adolfo; Longinotti, María Paula; Corti, Horacio Roberto The viscosity of supercooled glycerol aqueous solutions, with glycerol mass fractions between 0.70 and 0.90, have been determined to confirm that the Avramov-Milchev equation describes very well the temperature dependence of the viscosity of the binary mixtures including the supercooled regime. On the contrary, it is shown that the free volume model of viscosity, with the parameters proposed in a recent work (He, Fowler, Toner, J. Appl. Phys. 100 (2006) 074702), overestimates the viscosity of the glycerol-rich mixtures at low temperatures by several orders of magnitude. Moreover, the free volume model for the water diffusion leads to predictions of the Stokes-Einstein product, which are incompatible with the experimental findings. We conclude that the use of these free volume models, with parameters obtained by fitting experimental data far from the supercooled and glassy regions, lead to incorrect predictions of the deterioration rates of biomolecules, overestimating their life times in these cryopreservation media. © 2012 Elsevier Inc.

Metamorphic evolution of the Río de la Plata Craton in the Cinco Cerros area, Buenos Aires Province, Argentina Massonne, Hans-Joachim; Dristas, Jorge Anastasio; Martinez, Juan Cruz A metapelite and an interlayered granite were studied from the Cinco Cerros area ca. 65 km WNW of the city of Mar del Plata. Garnet in these samples is slightly zoned with core and rim compositions of pyr 17(gro + andr) 6spes 1.5alm 75.5 and pyr 13.5(gro + andr) 5.5spes 2alm 80, respectively, in the metapelite. Corresponding compositions in the granite are pyr 15(gro + andr) 3.5spes 3.5alm 78 and pyr 11(gro + andr) 3.5spes 4.5alm 81. We used the PERPLE_X computer software package to calculate P-T pseudosections. From the pseudosection of the metapelite P-T conditions of 6.7 kbar and 670 °C were derived for an early metamorphic stage. Subsequently, a pressure release occurred at decreasing temperatures. The final metamorphic P-T conditions recorded by the studied rock are 4.5 kbar and 600 °C compatible with the absence of cordierite, staurolite, and an Al 2SiO 5-phase. Garnet in the granitoid crystallized between 715 and 690 °C at a pressure around 7.7 kbar.U-Th-Pb age dating with the electron microprobe was performed. 16 analyses of monazite in the metapelite formed three clusters resulting in ages of I: 2073 ± 11.4 (1 σ) Ma, II: 1913 ± 11.0 (1σ) Ma, and III: 1805 ± 20.8 (1 σ) Ma. Thus, the Paleoproterozoic metamorphic event can be related to the Trans-Amazonian cycle and was followed by slow cooling.As our study area is close to the margin of the Río de la Plata Craton, where abundant magmatic arc-derived plutonic rocks are outcropping, we interpret the derived P- T data as follows: A heating event (not recorded by the studied rocks) resulted from magmas that intruded during the Trans-Amazonian cycle. This event was followed by slow exhumation, probably caused by erosion, accompanied by thermal relaxation. © 2012 Elsevier Ltd.

Cultivos agrícolas y su rol como reservorios de carbono y fuentes de energía Manrique, Silvina Magdalena; Franco, Ada Judith El objetivo del presente trabajo fue analizar el potencial de la biomasa residual agrícola generada desde las principales producciones del municipio de Coronel Moldes, provincia de Salta (ají, tabaco Criollo y tabaco Virginia) en cuanto a la mitigación de GEI responsables del sobrecalentamiento de la atmósfera. Se consideraron dos estrategias generales de mitigación: i) como reservorio de carbono (C) y ii) como fuente de energía renovable neutra en emisiones de C, que sustituiría parcialmente a los combustibles fósiles empleados. Se evaluó este potencial en relación con otras fuentes de biomasa para las cuales existían estudios previos en la zona. Si bien su aporte como reservorio de C no es permanente, permite dimensionar su contribución en relación a la biomasa natural de la zona. En cuanto fuente de energía, el empleo de esta biomasa posibilitaría evitar cerca de 500 tCO2/año (emisiones anuales de 90 ciudadanos) con beneficios económicos y ambientales.

Second harmonic generation microscopy as a powerful diagnostic imaging modality for human ovarian cancer Adur, Javier Fernando; Pelagati, Vitor B.; de Thomaz, Andre A.; Baratti, Mariana O.; Andrade, Liliana A. L. A.; Carvalho, Hernandes F.; Bottcher Luiz, Fátima; Lenz Cesar, Carlos In this study we showed that second-harmonic generation (SHG) microscopy combined with precise methods for images evaluation can be used to detect structural changes in the human ovarian stroma. Using a set of scoring methods (alignment of collagen fibers, anisotropy, and correlation), we found significant differences in the distribution and organization of collagen fibers in the stroma component of serous, mucinous, endometrioid and mixed ovarian tumors as compared with normal ovary tissue. This methodology was capable to differentiate between cancerous and healthy tissue, with clear cut distinction between normal, benign, borderline, and malignant tumors of serous type. Our results indicated that the combination of different image-analysis approaches presented here represent a powerful tool to investigate collagen organization and extracellular matrix remodeling in ovarian tumors.

Contribution of proteomics for diving into the lactic acid bacteria role and the modification of the food matrix during fermentation Fadda, Silvina G. Fermentation and drying can be considered as the oldest ways to preserve raw materials extending the shelf-life as well as enhancing the flavour and nutritional qualities of the products. Lactic acid bacteria (LAB) are the main agents responsible for fermentation, reducing the ripening time, minimizing manufacturing defects, improving sensory properties and inhibiting the development of pathogenic and spoilage flora. LAB is also considered as the most important microorganism responsible for the health-promoting effects of fermented foods, especially in milk-derived products. Indeed, strains of some species have traditionally been used as probiotics and added as functional bacteria in various food commodities [1]. Due to the huge economic significance of industrial application of LAB as starters, biopreservatives and probiotics, a research emphasis on their metabolism, genetic and applications has been placed in the last 25 years [2].

Application of bacteriocinogenic Enterococcus mundtii CRL35 and Enterococcus faecium ST88Ch in the control of Listeria monocytogenes in fresh Minas cheese Vera Pingitore, Esteban; Todorov, Svetoslav Dimitrov; Sesma, Fernando Juan Manuel; Franco, Bernadette Dora Gombossy de Melo Several strains of Enterococcus spp. are capable of producing bacteriocins with antimicrobial activity against important bacterial pathogens in dairy products. In this study, the bacteriocins produced by two Enterococcus strains (Enterococcus mundtii CRL35 and Enterococcus faecium ST88Ch), isolated from cheeses, were characterized and tested for their capability to control growth of Listeria monocytogenes 426 in experimentally contaminated fresh Minas cheese during refrigerated storage. Both strains were active against a variety of pathogenic and non-pathogenic microorganisms and bacteriocin absorption to various L. monocytogenes, Enterococcus faecalis ATCC 19443 and Lactobacillus sakei ATCC 15521 varied according to the strain and the testing conditions (pH, temperature, presence of salts and surfactants). Growth of L. monocytogenes 426 was inhibited in cheeses containing E. mundtii CRL35 up to 12 days at 8 C, evidencing a bacteriostatic effect. E. faecium ST88Ch was less effective, as the bacteriostatic affect occurred only after 6 days at 8 C. In cheeses containing nisin (12.5 mg/kg), less than one log reduction was observed. This research underlines the potential application of E. mundtii CRL35 in the control of L. monocytogenes in Minas cheese.

Actividad antimicrobiana de películas comestibles elaboradas a base de proteínas del lactosuero y glicerol incorporadas con sales orgánicas Perez, Leonardo Martin; Soazo, Marina del Valle; David, Mauricio; Rubiolo, Amelia Catalina; Verdini, Roxana Andrea El empleo de películas comestibles formuladas con compuestos antimicrobianos para recubrir alimentos es una forma de “envasado activo”. Mediante esta tecnología, se busca extender la vida útil de un producto alimenticio y disminuir la tasa de contaminación microbiana favoreciendo la seguridad de los consumidores. Los ácidos orgánicos y sus sales han sido utilizados ampliamente como aditivos alimenticios para controlar el desarrollo de patógenos y evitar la diseminación de enfermedades. En el presente trabajo, se evaluó el potencial antimicrobiano de películas comestibles elaboradas a base de proteínas del lactosuero (WPC) y glicerol (Gli) con la incorporación de sorbato de potasio (SP), benzoato de sodio (BS) y propionato de sodio (PS) frente a la cepa shigatoxigénica Escherichia coli O157:H7 ATCC 43895. La incorporación de las sales orgánicas en las películas ácidas de WPC/Gli obtenidas a pH 5,2 se realizó en cuatro concentraciones: 0,25%, 0,50%, 0,75% y 1,0% p/p. La actividad antimicrobiana se evaluó en medio agar Mueller-Hinton regulado a pH 5,2 a través de ensayos de difusión en agar y pruebas de barrera (cualitativa y cuantitativa). Además, se estudió la relación entre la capacidad antimicrobiana de las películas y la concentración de inóculo bacteriano (alto y bajo). El ensayo de difusión mostró que la incorporación de SP y BS a las películas comestibles de WPC/Gli redujo o inhibió el crecimiento de E. coli, excepto cuando la concentración de SP fue 0,25%. Este efecto fue más notorio a medida que la concentración de sales orgánicas en las películas aumentó y más evidente a inóculo bajo del patógeno. No se observó inhibición alguna ante la incorporación de PS en las películas. Los resultados de las pruebas de barrera cualitativa revelaron que tanto el SP como el BS a concentraciones iguales o superiores a 0,50% presentan excelentes propiedades para prevenir la contaminación externa, no siendo efectiva la adición de PS a las concentraciones ensayadas. Los resultados de las pruebas de barrera cualitativa y cuantitativa fueron coherentes con los obtenidos en los ensayos de difusión en agar. En conclusión, la adición de SP y BS a películas comestibles ácidas de WPC/Gli puede ser de suma utilidad para prevenir la contaminación post-proceso de los alimentos, demostrando un amplio potencial para su aplicación como recubrimiento activo en la industria alimentaria.

Direct and indirect photodynamic therapy effects on the cellular and molecular components of the tumor microenvironment Milla Sanabria, Laura Natalia; Rodriguez, Matias Exequiel; Cogno, Ingrid Sol; Rumie Vittar, Natalia Belen; Pansa, Maria Florencia; Lamberti, María Julia; Rivarola, Viviana Photodynamic therapy (PDT) is a novel cancer treatment. It involves the activation of a photosensitizer (PS) with light of specific wavelength, which interacts with molecular oxygen to generate singlet oxygen and other reactive oxygen species (ROS) that lead to tumor cell death. When a tumor is treated with PDT, in addition to affect cancer cells, the extracellular matrix and the other cellular components of the microenvironment are altered and finally this had effects on the tumor cells survival. Furthermore, the heterogeneity in the availability of nutrients and oxygen in the different regions of a tridimensional tumor has a strong impact on the sensitivity of cells to PDT. In this review, we summarize how PDT affects indirectly to the tumor cells, by the alterations on the extracellular matrix, the cell adhesion and the effects over the immune response. Also, we describe direct PDT effects on cancer cells, considering the intratumoral role that autophagy mediated by hypoxia-inducible factor 1 (HIF-1) has on the efficiency of the treatment.

The effect of an invading filter-feeding bivalve on a phytoplankton assemblage from the Parana´ system: a mesocosm experiment Frau, Diego; Rojas Molina, Florencia Mercedes; Devercelli, Melina; Jose, Susana Beatriz The effect of different concentrations of the bivalve Limnoperna fortunei on the algal density and structure and its filtration rate was estimated in a mesocosm experiment. The experiment was carried out using containers of 200 L and three treatments: Control (without bivalves), C1 (with 128 individual bivalves), and C2 (with 256 individual bivalves). Decrease in phytoplankton density was detected in bivalve treatments after 6 h. A decrease of 52% and 86% of the initial density was measured in C1 and C2, respectively, after 48 h. All algae groups showed substantial decrease in densities (>60%) and the composition of the algae assemblages changed in the presence of the bivalve. In particular, there was an increase in the density of Flagellates. The maximum estimated bivalve filtration rate was 357 mL ind−1 h−1 at 28°C. Our results suggest that the invading bivalves could significantly affect both the plankton density and assemblage structure in natural systems.