Mepyramine, a histamine H1 receptor inverse agonist, binds preferentially to a G protein-coupled form of the receptor and sequesters G protein Fitzsimons, Carlos P.; Monczor, Federico; Fernandez, Natalia Cristina; Shayo, Carina Claudia; Davio, Carlos Alberto Accurate characterization of the molecular mechanisms of the action of ligands is an extremely important issue for their appropriate research, pharmacological, and therapeutic uses. In view of this fact, the aim of the present work was to investigate the mechanisms involved in the actions of mepyramine at the guinea pig H(1) receptor stably expressed in Chinese hamster ovary cells. We found that mepyramine is able to decrease the basal constitutive activity of the guinea pig H(1) receptor, to bind with high affinity to a G(q/11) protein-coupled form of the receptor and to promote a G protein-coupled inactive state of the H(1) receptor that interferes with the G(q/11)-mediated signaling of the endogenously expressed ATP receptor, as predicted by the Cubic Ternary Complex Model of receptor occupancy. The effect of mepyramine on ATP-induced signaling was specifically neutralized by Galpha(11) overexpression, indicating that mepyramine is able to reduce G protein availability for other non-related receptors associated with the same signaling pathway. Finally, we found a loss of mepyramine efficacy in decreasing basal levels of intracellular calcium at high Galpha(11) expression levels, which can be theoretically explained in terms of high H(1) receptor constitutive activity. The whole of the present work sheds new light on H(1) receptor pharmacology and the mechanisms H(1) receptor inverse agonists could use to exert their observed negative efficacy.

Hodenmastzellen und männliche Infertilität; Testicular mast cells and male infertility. Mayerhofer, Artur; Meineke, V.; Weidinger, S.; Köhn, F. M.; Frungieri, Monica Beatriz Die Fibrose der Wand der Samenkanälchen ist eine seit langem bekannte typische Veränderung bei Männern mit Spermatogenesedefekten, deren Ursache und deren direkte Konsequenz aber nicht bekannt sind. Da im Hoden von Männern mit Spermatogenesestörungen deutlich vermehrt Mastzellen vorkommen, von denen viele aktiviert und degranuliert sind, ist zu erwarten, daß Produkte der Mastzellen freigesetzt werden. Wir stellen die Hypothese auf, daß sie an der Entstehung der Tubulusfibrose und der Spermatogenesestörung beteiligt sind. Untersuchungen in menschlichen Zellkulturen zeigten, daß Tryptase, das Hauptprodukt der Mastzellen, die Bildung von COX-2 und von Prostaglandinen stimuliert. Bestimmte Prostaglandine (J2/15dJ2) stimulieren dann über ihren Rezeptor (PPARgamma) das Fibroblastenwachstum, eine Voraussetzung für die Fibrose. Diese Ergebnisse sind für krankhafte Bindegewebsumbauvorgänge und speziell für die Tubulusfibrose bei Spermatogenesedefekten von Bedeutung: Bei Spermatogenesedefekten fanden wir, daß Mastzellvermehrung und Aktivierung mit der Expression von COX-2 in interstitiellen Zellen einhergehen. Bei Hoden mit normaler Spermatogenese (und nur wenigen Mastzellen) war COX-2 dagegen nicht nachweisbar. Rezeptoren für Tryptase sind auf interstitiellen Zellen und relevante Prostaglandinrezeptoren auf peritubulären Zellen nachweisbar. Es ist demnach möglich, daß Mastzelltryptase COX-2- und Prostaglandinbildung im infertilen Hoden anregt und dies letztlich zur Fibrose in der Tubuluswand führt, eine Veränderung, die sicherlich zur Spermatogenesestörung beiträgt. Die Aufklärung des Signalweges der Tryptase erlaubt es erstmals auch, gezielt über eine Beeinflussung des Fibroseprozesses nachzudenken: Mastzellstabilisatoren, Antagonisten von Tryptase, von COX-2 oder PPARgamma bieten sich an.; Fibrotic thickening of the wall of the seminiferous tubules is a hallmark of male infertility, but neither causes nor the direct consequences of tubular fibrosis are known. Since male infertility is also associated with increased numbers of activated mast cells, we propose that secreted mast cell products may be involved in the pathogenesis of tubular fibrosis and possibly male infertility. Evidence for this hypothesis is derived from cell culture and ex-vivo experiments: We found that actions of the major mast cell product, tryptase, includes formation of COX2 and synthesis of prostaglandins in target cells. Prostaglandin J2/15dJ2, which act via their receptor (PPARgamma), are responsible for fibroblast proliferation, a prerequisite of fibrosis. This may be of relevance for fibrosis in general and for testicular tubular fibrosis in particular: We found COX2 in testes of infertile men, but not of men with normal spermatogenesis, implying formation and action of prostaglandins. Since peritubular cells bear PPARgamma and since activated mast cells are at least tripled in infertile men, we propose a chain of events initiated by mast cell tryptase eventually leading to tubular fibrosis. Since tubular fibrosis is likely to be involved in the process leading to the damage of spermatogenesis, these results may pinpoint new targets for possible therapeutic interventions: mast cells, tryptase, COX2 and prostaglandins, as well as PPARgamma.

Description of the last larval instar and pupa of Aspisoma fenestrata Blanchard, 1839 (Coleoptera: Lampyridae) with brief notes on its biology Archangelsky, Miguel The last instar larva and pupa of Aspisoma fenestrata are described and figured for the first time. Notes for comparison with two other unidentified Aspisoma larvae are provided, as well as brief notes on the biology of A. fenestrata. Comparison of Aspisoma larvae with other known Cratomorphini larvae places Aspisoma closer to Pyractomena than to Cratomorphus.

Percolation of polyatomic species on square lattices Cornette, Valeria Cecilia; Ramirez Pastor, Antonio Jose; Nieto Quintas, Felix Daniel In this paper, the percolation of (a) linear segments of size k and(b) k-mers of different structures and forms deposited on a square lattice have been studied. In the latter case, site and bond percolation have been examined. The analysis of results obtained by using finite size scaling theory is performed in order to test the universality of the problem by determining the numerical values of the critical exponents of the phase transition occurring in the system. It is also determined that the percolation threshold exhibits a exponentially decreasing function when it is plotted as a function of the k-mer size. The characteristic parameters of that function are dependent not only on the form and structure of the k-mers but also on the properties of the lattice where they are deposited.

Ion exchange membranes derived from sulfonated polyaramides Taeger, A.; Vogel, C.; Lehmann, D.; Jehnichen, D.; Komber, H.; Meier Haack, J.; Ochoa, Nelio Ariel; Nunes, S.P.; Peinemann, K.-V. Homo- and both random and block copolyaramides of high molecular weights, with sulfonated moieties in the backbone, were obtained by low temperature polycondensation technique in a dipolar aprotic solvent (NMP) using (a) free aromatic diamines in the presence of pyridine as acid acceptor and (b) N,N ′-bis-trimethylsilyl derivatives of the diamines without additional acid acceptor. The addition of low molecular weight electrolytes (LiCl or CaCl2) and in some cases trimesoyl chloride to the reaction mixture was found to be favorable for the synthesis of high molecular weight polyamides. The materials had a theoretical ion exchange capacity of up to 3.14 meq/g. The membranes were characterized in terms of morphology, thermal stability, water-uptake, and ion exchange capacities.

Graptolites from the Upper Llandovery of the Talacasto area, Central Precordillera, San Juan, Argentina Lenz, Alfred; Cuerda, Alfredo; Peralta, Silvio Heriberto Graptolites are the most important biostratigraphic tool in the study of the Silurian of the Argentine Precordillera. Since, however, the graptolites are concentrated primarily in the Lower Llandovery and Ludlow of the region, the ages of parts of some stratigraphic units are poorly known. The recovery of a small Upper Llandovery graptolite assemblage in the lower one-third of the La Chilca Formation of the Talacasto area helps in resolving this problem, and that assemblage is the focus of this study. Brachiopods, trilobites, bivalves, and ostracodes are present in the same stratigraphic intervals, but are less common and less studied and, thus, of less biostratigraphic value.

Cuatro nuevas especies del género Liolaemus (Iguania: Liolemidae) perteneciente al grupo boulengeri de la Patagonia, Argentina.; Four new species of Liolaemus are described from the Patagonia region of southern Argentina. Abdala, Cristian Simón Se describen cuatro nuevas especies del género Liolaemus, pertenecientes al grupo boulengeri, caracterizado por la presencia de un parche femoral de escamas agrandadas en la parte posterior del fémur. Una especie fue colectada en el sur de la provincia de Neuquén y las otras tres en el suroeste, centro y este de la provincia de Río Negro, en la Patagónia Argentina. Dentro del grupo las nuevas especies están relacionadas fenéticamente a Liolaemus boulengeri. Se estudiaron 98 caracteres morfológicos externos, referidos principalmente a caracteres de lepidosis, patrón de coloración, y proporciones corporales, corrientemente estudiados en Liolaemus. Las diferencias mas significativas entre estas especies y Liolaemus boulengeri se dan principalmente en el patrón de coloración y en algunos caracteres de escamación. Estas especies ocupan parte de las tres regiones patagónicas que se diferencian con base en la orografía y vegetación asociada. Las nuevas especies del centro y suroeste de la provincia de Río Negro, soportan grandes diferencias de temperatura diarias y estaciónales. Las cuatro especies que se describen aquí se alimentan principalmente de insectos.; our new species of Liolaemus are described from the Patagonia region of southern Argentina. One species was collected in southern Neuquén Province and the other three are from Río Negro Province. Each of the new species has a patch of enlarged scales on the posterior surface of the thighs, indicating their relationship to members of the boulengeri group. Within this group, the four new species are morphologically most similar, and may be most closely related to, Liolaemus boulengeri. A total of 98 external morphological characters, principally squamation, color pattern, and body proportions, were recorded for these new members of the boulengeri group and compared with those for Liolaemus boulengeri. Significant differences between the new species and Liolaemus boulengeri were primarily in color pattern and some aspects of squamation. The new species are distributed over three Patagonian regions with differing geological histories and plant associations. The new species described from central and southwestern Río Negro Province experience substantial differences in daily and seasonal temperature. All four new species eat insects.

The depressor mandible muscle in anurans Manzano, Adriana Silvina; Moro, Silvina; Abdala, Virginia Sara Luz It is well known that the diversity in anuran cranial structures is large, observed in the variation of the bone structure and associated muscles. The depresso mandibulae is the jaw muscle that opens the mouth and was considered by many authors useful in delimiting anuran groups. However, there is still much controversy on the value of the m. depressor mandibulae as a relationship-indicating character. The goal of this project is to explore the morphological diversity of the depressor mandibulae muscle among different families of Anura. Specimens including 60 genera of 17 families of Anura were dissected, using traditional techniques of macroanatomy. Fifteen morphological groups can be distinguished within the anuran species analyzed. The insertion point demonstrates little variation. The overall pattern of the origin is also quite stable, with some exceptions. The great diversity in shape of the m. depressor mandibulae correlates with the plethora of patterns already mentioned for cranial morphology in anurans. However, it is difficult to asign a specific morphology to a given higher taxon. We also found no evidence that variations in the m. depressor mandibulae are associated with particular habits.

Two weighted inequalities for maximal functions related to Cesàro convergence Bernardis, Ana Lucia; Martín Reyes, Francisco Javier We characterize the pairs of weights (u, v) for which the maximal operator Mα- f (x) = supR>0 R-1-α ∫x-Rx-2R |f (s)|(x - R - s)α ds, -1 <α < 0, is of weak and restricted weak type (p, p) with respect to u(x) dx and v(x) dx. As a consequence we obtain analogous results for Mαf (x) = supR>0 R-1-α ∫R<|x-y|<2R |f(y)|(|x - y| -R)α dy. We apply the results to the study of the Cesàro-α convergence of singular integrals.

The Cesàro maximal operator in dimension greater than one Bernardis, Ana Lucia; Martín Reyes, Francisco Javier We consider a maximal operators defined on Rn which is related to the Cesaro continuity of functions. We characterize the weights w for which the maximal operator is of weak type, strong type and restricted weak type (p, p) with respect to the measure w(x) dx.

Metadiscurso y producción escrita en estudiantes universitarios" Padilla Sabate, Constanza En este trabajo se exponen las conclusiones de una investigación de campo acerca de los procesos de escritura y de metacognición en estudiantes universitarios. Los datos de los subprocesos de la producción escrita, se obtuvieron a partir de la adaptación de la técnica de protocolo de razonamiento en voz alta de L. Flower y J. Hayes (1996), aplicada en una población de 100 estudiantes universitarios, distribuidos en 20 grupos, a quienes se les solicitó la producción grupal de un artículo de opinión y la realización simultánea del protocolo por parte de un observador no participante. Para la recolección de datos de los aspectos metadiscursivos, se administró una encuesta semiestructurada a los mismos estudiantes, con el objetivo de hacer observables sus representaciones acerca de sus propios procesos, desde la enunciación explícita de sus dificultades discursivas. Del análisis, cuantificación e interpretación de los datos, se destacan problemas en el procesamiento de bajo nivel (gramática, ortografía y léxico), tanto a nivel discursivo como metadiscursivo, y dificultades recurrentes en el procesamiento de alto nivel (organización y jerarquización de las ideas, y monitoreo del proceso). Estas dificultades se infieren, fundamentalmente, a partir de la escasa verbalización sobre estos procesos y de la calidad de los productos escritos obtenidos. Los resultados de esta investigación son de especial relevancia para un replanteo de la didáctica de la lengua en los distintos niveles del sistema educativo.

Literatura testimonial en Argentina. Pájaros sin luz de Noemí Ciollaro (1999) Nofal, Silvia Rossana El trabajo postula las una lectura sobre las modulaciones de género en la escritura testimonial. La obra de Ciollaro se ubica en una zona gris, alejada de los relatos producidos en términos de victoria o derrota.

Los desafíos regionales frente a la mundialización de los territorios: La sociedad mendocina en los 90 Montaña, Elma Carmen En 1987, tras décadas de crisis de la economía provincial, Mendoza se embarcaba en la reestructuración del viejo modelo vitivinícola tradicional hacia uno más diversificado y orientado hacia las exportaciones. Las transformaciones derivadas del cambio del modelo económico nacional profundizaron este proceso. A más de 15 años de aquel momento y tras una década de debate académico en torno a las posibilidades y riesgos de las economías y los territorios de América Latina frente al pasaje de economías cerradas a modelos abiertos y sobre los efectos de las políticas neoliberales en aplicación, nos preguntamos de qué manera ha transitado Mendoza estas transfor­maciones. Específicamente, este trabajo se interesa por las fracturas y reposicionamentos ocurridos en la sociedad local y en la manera en la que se transformó el mapa de los actores operando en la provincia respecto del existente a fines de la década del 80. Se analiza la evolución de actores públicos y privados, locales y foráneos. Hubo ganadores, perdedores y una gama de actores que pelean su posición o incluso su supervivencia en el nuevo modelo y cuya suerte depende, en parte, de las opciones que se tomen para el futuro inmediato y de más largo plazo, de las estrategias que se adopten, de los recursos puestos en juego. Finalmente, se explica el interés en la cohesión social por su incidencia en la construcción de identidades compartidas y en el valor de éstas como factores endógenos necesarios a la construcción de un proyecto sustentable de desarrollo local.

Hochschild cohomology of incidence algebras as one-point extensions Gatica, María Andrea; Redondo, Maria Julia The aim of this paper is to compute the Hochschild cohomology groups of particular of algebras associated to partially ordered sets. © 2003 Elsevier Science Inc. All rights reserved.

Effect of undernutrition on the cranial growth of the rat: An intergenerational study Cesani Rossi, María Florencia; Orden, Alicia Bibiana; Zucchi, Mariel; Muñe, Maria Cristina; Oyhenart, Evelia Edith; Pucciarelli, Hector Mario The cumulative effect of undernutrition on successive generations was tested. The cranial growth of three generations of undernourished rats (F1, F2, F3) was compared to that of the parental generation (P), in order to (1) measure the extent to which the growth of each facial and neurocranial functional component was retarded when animals were undernourished and (2) determine whether any cumulative effect between generations can be found. The P generation was fed ad libitum, and the undernourished generations were fed 50% (F1) and 75% (F2 and F3) of the parental diet. Nine radiographs were taken from the age of 20-100 days. The length, width and height of the neurocranial and facial components were measured on each radiograph. Neurocranial (VNI), facial (VFI), and neurofacial (NFI) indices were calculated. Data were processed by the Kruskal-Wallis and Kolmogorov-Smirnov tests. An impairment in neurocranial and facial growth was found, the latter being more affected than the former in F1. At variance, the neurocranium was more affected than the face in F2 and F3, resulting in variations of the shape of the skull. A cumulative effect of moderate transgenerational undernutrition was evident and points to the need for further analysis on this topic. Copyright © 2003 S. Karger AG, Basel.

Las especies invasoras exóticas en los sistemas de Humedales: El caso del Delta Inferior del Río Paraná; Exotic invader species in wetland ecosystems: The case of the low Delta of the Parana River Kalesnik, Fabio Alberto; Malvarez, Ana Ines Wetlands are ecosystems whose functioning relies on hydrologic regimes and small variations of flooding pulses or flooding levels that may produce massive changes in the local biota. These systems are particularly vulnerable to invasion processes, where variations of hydrologic regimens may cause changes in community composition and structure, and are considered to be one of the causes of incorporation of alien species. The delta of the Paraná river may be considered as a mosaic of wetlands, where 11 landscape units may be characterized by different flooding regimes and landscape patterns. In particular, the “Lower Delta Islands” Unit, is characterized by a highly fragmented landscape constituted by natural (marsh and relict patches of native forests) and anthropic environments (Salix commercial afforestations). These juxtapositions may increase considerably the probability of dispersion of alien species. Burkart (1957) mentions 29 exotic species for natural environments. In more recent works only 11 exotic species are mentioned. Lowland environments (marsh) present 4 exotic species (iris, Iris pseudacorus; honeysuckle, Lonicera japónica; Chinese privet, Ligustrum sinense and blackberry, Rubus spp.) but these species do not behave as invaders, since they present very low constancy and cover values. On the other hand, relict patches of native forests, present high cover values for privet, (Ligustrum lucidum), honeysuckle, White mulberry (Morus alba), and maple (Acer negundo). What respects anthropic environments, Valli (1990) analyzed succesional trends in lowland forestations, mentioning 5 exotic species (iris, Faux indigo (Amorpha fructicosa), honeysuckle, and privet), all of them with low cover values. Kalesnik (2001) studied commercial forestations on levee that presented 16 exotic species, of which only 7 behaved as invaders: privet, Fraxinus pennsylvanica, black acacia (Gleditsia triacanthos), honeysuckle, blackberry, maple and Ligustrum lucidum. The development of each species varied among different subunits (“A”, “B” or “C”) of the Lower Delta. While unit “A” presented a very low invasion index, low cover development of alien, and none of the species behaving as invaders, the other two units (“B” and “C”) presented mean values of the invasion index and a high cover of the mentioned exotic species. In unit “A”, the fluvial influence of the Paraná river, acting together with extraordinary flooding events and the fire caused intentionally for hunting activities, may be a possible explication for the absence of invader species. Finally, it may be stated that of a total of 102 exotic species introduces in the Lower Delta, 8,82% behave as invaders in the island sector. This value is in concordance with the pattern found for temperate ecosystems, where only a 10% of introduced species behave as invaders, in contrast to tropical ecosystems, where that proportion is close to 100%.

Molecular mechanisms of inhibition of nicotinic acetylcholine receptors by tricyclic antidepressants Gumilar, Fernanda Andrea; Arias, Hugo Rubén; Spitzmaul, Guillermo Federico; Bouzat, Cecilia Beatriz In addition to their well known actions on monoamine reuptake, tricyclic antidepressants have been shown to modulate ligand-gated ion channels (LGICs). Since the muscle nicotinic acetylcholine receptor (AChR) has been the model for studying structure-function relationships of LGICs, we analyzed the action of tricyclic antidepressants on this type of AChR at both single-channel and macroscopic current levels. We also determined their effects on ACh equilibrium binding and their interactions with the different conformational states of the AChR. Antidepressants produce a significant concentration-dependent decrease in the duration of clusters of single-channels (eight fold at 20 μM). They also decrease the peak amplitude and increase the decay rate of currents elicited by rapid perfusion of ACh to outside-out patches. In equilibrium binding assays, antidepressants promote the typical high-affinity desensitized state and inhibit binding of [piperidyl-3,4-3H (N)]-(N-(1-(2-thienyl) cyclohexyl)-3,4-piperidine ([3H]TCP) to its locus in resting and desensitized AChRs. The results indicate that tricyclic antidepressants: (i) interact with resting (closed), open, and desensitized channels; (ii) do not affect significantly channel opening and closing rates; (iii) do not act as fast open-channel blockers; (iv) inhibit activation of resting channels; and (v) may increase the rate of long-lived desensitization from the open state.

Phase space structure of multi-dimensional systems by means of the mean exponential growth factor of nearby orbits Cincotta, Pablo Miguel; Giordano, Claudia Marcela; Simó, C. In this paper we deal with an alternative technique to study global dynamics in Hamiltonian systems, the mean exponential growth factor of nearby orbits (MEGNO), that proves to be efficient to investigate both regular and stochastic components of phase space. It provides a clear picture of resonance structures, location of stable and unstable periodic orbits as well as a measure of hyperbolicity in chaotic domains which coincides with that given by the Lyapunov characteristic number. Here the MEGNO is applied to a rather simple model, the 3D perturbed quartic oscillator, in order to visualize the structure of its phase space and obtain a quite clear picture of its resonance structure. Examples of application to multi-dimensional canonical maps are also included.

Geomorphologic, circulation and dynamic analysis in a meandering tidal channel, Bahía Blanca Estuary Angeles, Guillermo Raul; Perillo, Gerardo Miguel E.; Piccolo, Maria Cintia A meander of La Lista tidal channel (Bahia Blanca Estuary, Argentina) was selected in order to study the relationship between the geoforms that control the meandering channel evolution (mainly tidal flats and marshes) arid the dynamic and circulation characteristics of these channels. To achieve this goal a general survey was made in August 1999. The topographic characteristics of the channel and cross- section profiles from different sectors of the meander were compared with typical river profiles. Morphologic similarities between meander tidal channel cross-section (characterized by bidirectional flows) and meander river cross-section (characterized by unidirectional flows) were analysed. The largest velocities were measured during the ebb period (87 and 67 em S·l for U and V, respectively); during the flood period, the highest values registered were 53 and 33 em S·1 for U and V, respectively. Differences among the tidal current profiles along the meander were observed. Comparing the current velocity gradients in the different stations, the higher variations were observed during the flood period.

Gelation of beta-lactoglobulin in the presence of propylene glycol alginate: kinetics and gel properties Baeza, Rosa Isabel; Gugliotta, Luis Marcelino; Pilosof, Ana Maria Renata The role of the non-gelling polysaccharide, propyleneglycol alginate (PGA), on the dynamics of gelation and gel properties of β-lactoglobulin (β-lg) under conditions where the protein alone does not gel (6%) was analyzed. To this end, the kinetics of gelation, aggregation and denaturation of β-lg in the mixed systems (pH 7) were studied at different temperatures (64–88 °C). The presence of PGA increased thermal stability of β-lg. The rate of β-lg denaturation was decreased and the onset and peak denaturation temperatures increased by 2.2–2.4 °C. PGA promoted the formation of larger aggregates that continued to grow in time. An average aggregate diameter of approximately 300 nm is reached at the gel point in the mixed β-lg+PGA systems, irrespective of the heating temperature. Comparing the activation energies for the aggregation (193 kJ/mol), denaturation (422 kJ/mol) and formation of the primary gel structure (1/tgel) (256 kJ/mol) processes in the mixed protein–polysaccharide system, it can be concluded that the rate determining step in the formation of the primary gel structure would be the aggregation of protein. Ea values for the processes after the gel point (solid phase gelation) suggest a diffusion limited process because of the high viscosity of the solid gelling matrix. The characteristics of the mixed β-lg+PGA gels in terms of rheological and textural parameters, water loss and microstructure were studied as a function of heating temperature and time. The extent of aggregation and the type of interactions involved, prior to denaturation seem to be very important in determining the gel structure and its properties.