Estrogens and neuroendocrine hypothalamic-pituitary-adrenal axis function de Nicola, Alejandro Federico; Saravia, Flavia Eugenia; Beauquis, Juan; Pietranera, Luciana; Ferrini, Monica G. The function of the HPA axis is subject to regulation by many factors, which achieve relevance under normal and pathological conditions. In the case of aging, this period of life is associated with disturbances of the HPA axis and signs of hippocampal vulnerability. We examined 20-month-old male rats, in which abnormalities of the HPA axis included altered response to stress, reduced effectiveness of the steroid negative feedback and low expression of hippocampal glucocorticoid receptors (GR). Estrogen treatment of aging rats normalized the response to stress, restored the dexamethasone inhibition of the stress response and increased GR density in defined hippocampal areas. Although estrogens could influence the hippocampus of aging animals directly, their effects could be also mediated by estrogen-sensitive forebrain cholinergic neurons projecting to the hippocampus. Additionally, estrogens normalized the deficient granule cell proliferation that aging mice present in the dentate gyrus, and attenuated several markers of hippocampal aging, such as astrocytosis, high lipofucsin content and neuronal loss in the hilus of the dentate gyrus. These effects may be important for the regulation of the HPA axis, in the context that hippocampal function as a whole was normalized by estrogen action. Therefore, estrogens are powerful neuroprotectants in cases of hippocampal dysfunction, and as part of this effect, they contribute to stabilize the function of the HPA axis.

Vegetación Menghi, Mirta Melva Mercedes Las primeras descripciones de la vegetación de Mar Chiquita provienen de Federico Kurtz en la Geografia de la provincia de Córdoba de Ríos & Achaval (1904), y del mapa fitogeográfico que  Kanter (1935) publica como parte de un análisis geográfico detallado de la cuenca de Mar Chiquita. En su obra sobre la vegetación del norte de Córdoba, Sayago (1969) realizó un estudio amplio y detallado de la vegetación de Mar Chiquita y los bañados del Río Dulce, el cual incluye un mapa de la vegetación a escala 1:400000. Este relevamiento se llevó a cabo en un período previo a las grandes inundaciones iniciadas a fines de la década de 1970. Posteriormente  Luti et al. (1979) elaboraron una nueva revisión de la vegetación del área. Mas recientemente Menghi & Herrera (1995; 1996) analizaron en detalle la diversidad florística y aspectos funcionales de la vegetación de la depresión de Mar Chiquita, así como la relación con el relieve y la hidrología (del Sueldo 1995) y con la producción primaria en bañados del Río Dulce (Menghi & Herrera 1998; Menghi et al. 2003).

Automated method for the total creatinine determination in dehydrated broths Acebal, Carolina Cecilia; Centurión, María Eugenia; Lista, Adriana Guillermina; Fernández Band, Beatriz Susana In order to improve the quality control of dehydrated broth, a new automated method was developed to determine total creatinine in dehydrated broths. The sample pretreatment was coupled on-line with the Flow Injection Analysis (FIA) system for analyte determination by the classical Jaffe reaction, stopped flow methodology, and spectrophotometric detection. The time consumed was reduced from 7h, which is necessary with the official method, to 25 min. The calibration graph is linear between 0.342-1.368 mg creatinine/ 100 mL. The relative standard deviation (RSD%) was 1.7%, the sample throughput was 7 h -1, and the detection limit was 0.185 mg creatinine/100 mL. The validation of the proposed method was carried out with real samples. The obtained results were compared with those obtained from the Association of Official Analytical Chemists (AOAC) reference method.

Ostracods (Crustacea) from thermal waters, southern Altiplano, Argentina Laprida, Cecilia; Diaz, Analia Roxana; Ratto, Norma Rosa The ostracod fauna from la Terma hot spring (26°55′31″ S - 68°08′45.7″W, 4026m above sea level), Southern Altiplano, Argentina, is described and the pool itself characterized. The occurrence of ostracods in this type of environments is registered for the first time in Argentina. Six species were found, two of which are new to the fauna of Argentina: Penthesilenula incae (Delachaux) and Hemicypris panningi (Brehm). Two species were found for the first time in the Altiplano: H. panningi (Brehm) and Cypridopsis fuhrmanni (Méhes). Some comments concerning how and when these species could spread to populate the Dry Altiplano are discussed briefly taking into account paleoclimatic data. This paper provides the first record of recent ostracods from the Southern Altiplano, Argentina.

Administration of corticosterone after the first downshift trial enhances consummatory successive negative contrast Bentosela, Mariana; Muzio, Ruben Nestor; Ruetti, Eliana Martha; Mustaca, Alba Elisabeth; Papini, Mauricio Roberto Rats given access to a 32% sucrose solution and then downshifted to a 4% solution exhibit less contact with the sipper tube than unshifted controls always given access to 4% solution. This phenomenon, called consummatory successive negative contrast, was facilitated in Experiment 1 by a post-trial injection of corticosterone (3 mg/kg) administered immediately after the first downshift trial. Experiment 2 demonstrated that this facilitatory effect of post-trial corticosterone does not occur when administered 3 hr after the first downshift trial. These results support the hypothesis that corticosterone strengthens an aversive emotional component elicited by the surprising downshift in reward magnitude during the initial downshift trial.

A kinetic study on the inhibitory action of sympathomimetic drugs towards photogenerated oxygen active species: The case of phenylephrine Massad, Walter Alfredo; Bertolotti, Sonia Graciela; Romero, Mario Raul; Garcia, Norman Andino Kinetics and mechanism of the aerobic Riboflavin (Rf, vitamin B2) sensitized photodegradation of Phenylephrine (Phen), a phenolamine belonging to the sympathomimetic drugs family, has been studied in water, employing continuous photolysis, polarographic detection of oxygen uptake, steady-state and time-resolved fluorescence spectroscopy, time-resolved IR-phosphorescence and laser flash photolysis. Results indicate the formation of a weak dark complex Rf–Phen, with an apparent association constant of 5.5 ± 0.5 M 1 , only detectable at Phen concentrations much higher than those employed in the photochemical experiments. Under irradiation, an intricate mechanism of competitive reactions operates. Phen quenches excited singlet and triplet states of Rf, with rate constants of 3.33 ± 0.08 and 1.60 ± 0.03 · 109 M 1 s 1 , respectively. With the sympathomimetic drug in a concentration similar to that of dissolved molecular oxygen in water, Phen and oxygen competitively quench triplet excited Rf, generating superoxide radical anion and singlet molecular oxygen (O2( 1 Dg)) by processes initiated by electron- and energy-transfer mechanisms respectively. As a global result, the photodegradation of the vitamin, a known process taking place from its excited triplet state, is retarded, whereas the phenolamine, practically unreactive towards these oxidative species, behaves as a highly efficient physical deactivator of O2( 1 Dg). The phenolamine structure in Phen appears as an excellent scavenger of activated oxygen species, comparatively superior, in kinetic terms, to some commercial phenolic antioxidants.

Effect of the drug-excipient ratio in matrix-type-controlled release systems: Computer simulation study Villalobos, Rafael; Ganem, Adriana; Cordero, Salomón; Vidales, Ana Maria; Domínguez, Armande The main objective of this work is to study the drug release behavior from inert matrix systems by using computer simulation. This study allowed us to propose a new statistical method to evaluate the drug percolation threshold as a function of the exposed surface area of the device. The matrix system was simulated as a simple cubic lattice. The sites of the lattice were randomly occupied at various drug-excipient ratios. By simulating a diffusive process, the drug was delivered from the matrix system. The obtained release profiles were fitted to two different models: near the excipient percolation threshold, the square root of the time was well fitted, whereas close to (but above) the drug percolation threshold, the power law described accurately the release data. A relationship between the initial drug load and the amount of drug trapped inside the matrix system at infinite time was found. This relationship was conveniently described by an error function. Percolation thresholds in the matrix systems were determined from the latter relationship by using a nonlinear regression method. The assessment of percolation thresholds depends on the exposed surface area of the matrix systems. Moreover, estimated percolation thresholds were in agreement with the predicted values stated in the percolation theory.

The natural vector bundle of the set of multivariate density functions Marchi, Ezio; Morillas, Patricia Mariela We find a description of the set of multivariate density functions with given marginals and introduce an associated vector bundle. The interest for the probability theory is restricted to the nonnegative elements in the sets of the derived vector bundle. The fiber is the space of all correlation measures among a multivariate density function and its unidimensional marginals.

Stability of Araujiain, a novel plant protease, in different organic systems; Estabilidad de Araujiaína, una nueva fitoproteasa, en diferentes sistemas orgánicos Quiroga, Evelina; Priolo, Nora Silvia; Marchese, Jose; Barberis, Sonia Esther The effect of different organic solvents on the stability of araujiain(the crude enzyme preparation obtained from the latex of fruits of Araujia hortorum Fourn., Asclepiadaceae) in mixtures of buffer and different water-miscible or immiscible organic solvents, and in continuous systems (organic solvents with low water activity) after 4 h at 40 ºC was studied in this paper in order to select the most adequate media for peptide enzymatic synthesis. Araujiainshowed the highest stability in 50% hexane, 50% propanone, and N,N-dimethylformamide (aw: 0.5 in the enzyme), and those values were remarkably greater than in buffer. In addition, the presence of those organic solvents reduced the autolysis degree. In general, araujiainwas not inactivated in aqueous-miscible organic systems and the enzyme showed higher activities in those media than in buffer. In biphasic systems, the partition of the organic solvents into the aqueous phase activated the enzyme in several cases. These results did not agree with those obtained in continuous systems, because many of them inactivated the enzyme. Nevertheless, in N,N-dimethylformamide (aw: 0.5 in the enzyme) araujiainshowed a remarkable stability after 4 h, and it displayed a higher activity in this organic solvent than in aqueous medium. From these results, it is evident that araujiain in the presence of most of the studied organic systems did not suffer unfolding and it was able to retain its native or native-like configuration, though with altered characteristics or properties. This fact was demonstrated by means of comparative FTIR spectroscopy studies for araujiainin buffer and non-aqueous systems.; Con el objeto de seleccionar los medios más adecuados para la síntesis enzimática de péptidos, estudiamos el efecto de diferentes solventes orgánicos sobre la estabilidad de araujiaina(la preparación enzimática no purificada obtenida del látex de frutos de Araujia hortorumFourn., Asclepiadaceae) en mezclas de buffer y diferentes solventes orgánicos miscibles o inmiscibles con el agua y en sistemas continuos (solventes orgánicos con baja actividad de agua), luego de 4 h a 40 °C. Araujiainamostró la mayor estabilidad en hexano (50%), propanona (50%) y en N,N-dimetilformamida (aw: 0,5 en la enzima), siendo aquellos valores marcadamente más elevados que en buffer. Además, la presencia de aquellos solventes orgánicos redujo el grado de autólisis. En general, en sistemas miscibles araujiainano fue inactivada, mostrando actividades más altas que en buffer. En sistemas bifásicos, la partición de los solventes orgánicos en la fase acuosa produjo en numerosos casos una considerable activación de la enzima. Por el contrario, la mayoría de los sistemas continuos inactivaron la enzima. Sin embargo, en N,N-dimetilformamida (aw: 0,5 en la enzima) araujiaina fue estable luego de 4 h y más activa que en medio acuoso. De los resultados aquí presentados hay evidencias de que araujiainano sufrió desdoblamiento en presencia de la mayoría de los sistemas orgánicos estudiados y fue capaz de retener su conformación nativa o semejante a la nativa pero con características o propiedades alteradas. Este hecho fue demostrado por medio de estudios comparativos de espectroscopía FTIR para araujiainaen buffer y en sistemas no acuosos.

A particle swarm optimizer for multi-objective optimization Cagnina, Leticia Cecilia; Esquivel, Susana Cecilia; Coello Coello, Carlos This paper proposes a hybrid particle swarm approach called Simple Multi-Objective Particle Swarm Optimizer (SMOPSO) which incorporates Pareto dominance, an elitist policy, and two techniques to maintain diversity: a mutation operator and a grid which is used as a geographical location over objective function space. In order to validate our approach we use three well-known test functions proposed in the specialized literature. Preliminary simulations results are presented and compared with those obtained with the Pareto Archived Evolution Strategy (PAES) and the Multi-Objective Genetic Algorithm 2 (MOGA2). These results also show that the SMOPSO algorithm is a promising alternative to tackle multiobjective optimization problems.

La configuración del poder en los espacios de trabajo: Dispositivos disciplinarios y resistencia de los trabajadores Montes Cato, Juan Sebastian El artículo analiza las relaciones de poder en los espacios de trabajo en Argentina durante la década de lo noventa. Para ello se seleccionó el sector de las empresas de telecomunicaciones como caso testigo. Nos interesa resaltar la articulación existente entre la flexibilización laboral y los diversos dispositivos de disciplinamiento. Esto permitirá analizar la configuración adoptada por los procesos de dominación del capital. Puesto que las relaciones laborales son esencialmente conflictivas, se estudian las acciones de resistencia desde una perspectiva que recupera aquellos aspectos materiales como los simbólicos. El estudio concluye que el denominado “proceso de modernización” implicó mayor precarización en las condiciones de trabajo y una profundización de la explotación de la fuerza de trabajo.; This article analyses the relations of power in the workplace in Argentina during the decade of the nineties. For it witness selected the sector of the companies of telecommunications. We are interested in highlighting the existing joint the labour flexibility and discipline at work. This will along to analyse the configuration adopted as a processes of domination. Since labour relations are essentially conflict, the actions of resistance are studied from a perspective that recovers those material aspects as the symbolic ones. The study concludes that called “process of modernization” involved major vulnerability in work conditions and a deepening of the exploitations of workforce.

A South American bioinvasion case history: Limnoperna fortunei (Dunker, 1857), the golden mussel Darrigran, Gustavo Alberto; Damborenea, Maria Cristina Two factors combine in this age of globalization to favor the establishment of alien species in natural environments: human activities and global climate change. This paper reviews the recent invasion of the golden mussel, Limnoperna fortunei, in South America, including its impacts in natural and human environments. This case study allows the identification of the likely impacts that morphologically and functionally similar invasive species will have in similar environments, such as in North America, which is considered to be at high risk of invasion by L. fortunei.

The radical-based reduction with (TMS)3SiH 'on water' Postigo, Jose Alberto; Ferreri, Carla; Navacchia, Maria Luisa; Chatgilialoglu, Chryssostomos Reduction of different organohalides, bromonucleosides among them, was successfully carried out in yields ranging from 75% to quantitative, using (TMS)3SiH in a heterogeneous system with water as the solvent. Our procedure, employing 2-mercaptoethanol as the catalyst and the hydrophobic diazo-compound ACCN as the initiator, illustrates that (TMS)3SiH can be the radical-based reducing agent of choice in aqueous medium. (TMS) 3SiH does not suffer from any significant reaction with water and can safely be used with additional benefit, such as ease of purification and environmental compatibility.

Orexin A stimulates hypothalamic-pituitary-adrenal (HPA) axis function, but not food intake, in the absence of full hypothalamic NPY-ergic activity Moreno, Griselda Noemí; Perello, Mario; Gaillard, Rolf C.; Spinedi, Eduardo Julio Neonatal monosodium L-glutamate (MSG) treatment destroys hypothalamic arcuate nucleus neuronal bodies, thus inducing several metabolic abnormalities. As a result, rats develop a phenotype characterized by hyperleptinemia and by impaired NPY but normal preproorexin hypothalamic mRNAs expression. Thus, our study was designed to explore whether hypothalamic effects of orexin A on food intake and glucocorticoid production develop in the absence of full hypothalamic NPY-ergic activity. For this purpose we evaluated, in control and MSG-treated rats, the consequences of intracerebroventricular (icv) orexin A administration on food intake and changes in circulating levels of ACTH and glucocorticoid. Our results indicate that orexin A icv treatment stimulated hypothalamic-pituitary-adrenal (HPA) axis activity in both MSG-damaged and normal animals, with this response even more pronounced in neurotoxin-damaged rats. Conversely, food intake was only enhanced by icv orexin A injection in normal rats. Our study further supports that acute hypothalamic effects of orexin A on food intake and glucocorticoid production are due to independent neuronal systems. While intact arcuate nucleus activity is needed for the orexinergic effect induced by icv orexin A administration, conversely, orexin A-stimulated HPA axis function takes place even in the absence of full NPY-ergic activity.

Thyrotropin-releasing hormone in cardiovascular pathophysiology Garcia, Silvia Ines; Pirola, Carlos José Thyrotropin (TSH)-releasing hormone (TRH) also known as thyroliberin was the first of a number of peptides exerting several roles as a hormone and as a neuropeptide. Its ubiquitous distribution in the hypothalamus and in the extrahypothalamic regions and its diverse pharmacological and physiological effects are all features of its dual functions. For this reason, TRH has been the subject of much research throughout the past 20 years, work that has examined the structure, function, distribution, and regulation of the tripeptide and it has been extensively reviewed elsewhere [O´Leary R., O´Connor B. Thyrotropin-releasing hormone. J Neurochem. 1995;65:953-963.; Nillni E., Sevarino K. The biology of pro-thyrotropin-releasing hormone-derived peptides. Endocrine Reviews, 1999;20:599-664.]. After a brief overview of its distribution, hypothalamic and extrahypothalamic functions, and receptors involved, this review discusses efforts devoted to support TRH role in cardiovascular regulation with a main focus on hypertension pathophysiology in experimental models and humans.

Imágenes de la periferia. Las exploraciones de Juan Francisco de Aguirre y su historia y geografía de las Provincias del Río de la Plata Brezzo, Liliana Maria Este artículo estudia las exploraciones y los escritos del Capitán de Fragata Juan Francisco de Aguirre en Paraguay y Argentina entre 1784 y 1796. Recapitula las circunstancias y las características historiográficas que determinaron la producción de su Historia y Geografía del Río de la Plata. Este trabajo desea también llamar la atención en una cuestión principal: la posibilidad, a través de este escrito,  de reconstruir y entender las estructuras de la región paraguaya durante el siglo XVIII. Los resultados de este artículo provienen de la visita a los manuscritos de Aguirre depositados en la Real Academia de la Historia de Madrid (España), en el Museo Naval de El Viso (España) y en el Archivo Nacional de Asunción (Paraguay).

Solar UV-B influences microfaunal community composition in a Tierra del Fuego peatland Robson, T. Matthew; Pancotto, Veronica Andrea; Scopel, Ana Leonor; Flint, Stephan D.; Caldwell, Martyn M. The peatlands of Tierra del Fuego are subject to increased solar ultraviolet-B radiation (UV-B) due to the influence of the Antarctic "ozone hole". Research into the effects of climate change and ozone depletion on peatlands has predominantly focused on the higher plant community and neglected other organisms. In the second 3-year portion of a 6-year experiment, we intensified our investigations of the response of the peatland surface microfaunal community to current and attenuated solar UV-B, and assessed possible links to changes in the microenvironment. Near-ambient UV-B and reduced UV-B treatments were realised by stretching plastic film filters that differentially attenuate UV-B over peatland sample plots. We extracted the microfauna and analysed the dissolved nutrients held within Sphagnum capitula removed from the top 1-cm of the peatland. In line with previous findings in this system, testate amoebae were more abundant under near-ambient UV-B than under reduced UV-B. Populations of the most common genus, Assulina, and other less prominent amoebae species of Heleopera and Euglypha, were consistently increased under near-ambient UV-B. Overall diversity of testate amoebae was also higher under near-ambient UV-B than under reduced UV-B, whereas rotifers, nematodes and mites were less abundant under near-ambient UV-B. Concentrations of DOC and P were generally higher under near-ambient UV-B than under reduced UV-B. These changes, combined with the changes previously reported in the plant and fungal communities, have the potential to influence peatland C storage, and surface nutrient availability. The peatland microfaunal community under near-ambient solar UV-B may be regulated by the plant community through the leaching of nutrients from leaf cells, and changes in Sphagnum morphology that affect the capitulum microenvironment.

The parasite behavior hypothesis and the use of sleeping sites by black howler monkeys (Alouatta caraya) in a discontinuous forest Kowalewski, Miguel Martin; Zunino, Gabriel Eduardo The selection of high trees to sleep is a common pattern in primates (Anderson, 1984). In this study howlers slept in tall trees characterized by a closed crown, possibly related to a reduction in predation. We also found selectivity in the trees used as sleeping sites because these trees were not the most abundant in the forest. Selection of sleeping trees was consistent with a predator avoidance hypothesis: Ficus and Tabeuia were the tallest trees in the forest and possibly provided protection against. We also found evidence in support of a thermoregulation hypothesis: they always slept huddled as a group, a social hypothesis: the large crowns of the selected trees allowed the groups to sleep together all the times, a safety hypothesis: trees selected offered large branches and crowns to accommodate the individuals, and a feeding site hypothesis: Ficus trees constituted the most important species in howlers' diet. Although the selection of sleeping trees was consistent with several alternative hypotheses, it was not consistent with parasite avoidance. Parasite avoidance did not appear to have exerted a strong selective pressure on the use of sleeping trees.

De dioses, fábulas y pobreza (Aspectos jurídicos de la normativa vigente sobre biotecnología agropecuaria) Miranda, Marisa Adriana; Perea Deulofeu, Natalia El objetivo principal del presente artículo consiste en realizar una relectura crítica de la regulación normativa de la agrobiotecnología actual, en el derecho interno y en los principales instrumentos internacionales, tomando los cuestionamientos científicos originados en su mismo contexto de emergencia: las Ciencias de la Naturaleza.

Faunistic records of proturans from Argentina (Insecta: Protura); Registros Faunísticos de Proturos en Argentina (Insecta: Protura) Szeptycki, Andrzej; Bedano, José Camilo Berberentulus nelsoni Tuxen, 1976 and Gracilentulus sp. are recorded in soils from Argentina. For our knopwledge, the two acerentomids reported in this paper represent the first records of both species from Argentina. Specimens were collected in Córdoba province, during the months of November 2000 and April 2001.; Berberentulus nelsoni Tuxen, 1976 y Gracilentulus sp. son registrados en suelos de Argentina. Estos dos acerentomidos reportados en este trabajo probablemente representan el primer registro de ambas especies para Argentina. Los especímenes fueron colectados en la provincia de Córdoba, durante los meses de noviembre de 2000 y abril de 2001.