Isolation of antibacterial components from infusion of Caesalpinia paraguariensis bark. A bio-guided phytochemical study Sgariglia, Melina Araceli; Soberon, Jose Rodolfo; Sampietro, Diego Alejandro; Quiroga, Emma Nelly; Vattuone, Marta Amelia The antimicrobial activities and toxicity of infusion, decoction and tincture of Caesalpinia paraguariensis Burk. bark (CPBEs) were investigated to validate its traditional use as drink additive and to identify microbicidal component(s). The minimum inhibitory concentrations (MIC) of CPBEs against aerobic bacteria (Gram-negative and Gram-positive species) were determined using standardised dilution methods. The LC 50 were determined by Brine Shrimp Test. CPBEs showed bacteriostatic and bactericidal activity against tested strains. The highest activity was observed for infusion (MIC:200 μg/mL) against Morganella morganii, Erwinia carotovora, Bacillus spp., Staphylococcus spp. and Enterococcus spp. The bacterial species were susceptible to CPBEs (MIC:200-1993 μg/mL) at lower concentration than sodium benzoate, a known food preservative. Two bioactive components were isolated from liophylised infusion by bio-guided chromatographic procedures; these were identified by spectrometric techniques as ellagic and 3-O-methylellagic acids. This study demonstrated that C. paraguariensis bark infusion it is safe for human consumption and a possible source of food natural preservatives.

La política latinoamericana en el Bicentenario: los avatares de la democracia Jensen, Silvina Inés A la luz de los debates en torno a los bicentenarios de la independencia, este artículo hace foco en la coyuntura de máxima impugnación democrática en la región, cuando bajo las dictaduras de la Doctrina de la Seguridad Nacional la oposición antidictatorial hizo de la defensa de los derechos más elementales de la persona su bandera de lucha y la piedra basal de la convivencia política deseada. En tal sentido analizaremos qué queda de esas luchas antidictatoriales y por la democracia de los años 1970 y 1980 de cara a ponderar qué se ha resignado y qué se ha conquistado, qué se ha consolidado y qué se ha abandonado y en qué medida los altos niveles de inequidad, pobreza y exclusión que acredita en la actualidad el subcontinente constituyen o no amenazas a la institucionalidad democrática.

The effect of economic variables over a biodiesel production plant Marchetti, Jorge Mario Biodiesel appears as one of the possible alternative renewable fuels to substitute diesel fuel derived from petroleum. Several researches have been done on the technical aspects of biodiesel production in an attempt to develop a better and cleaner alternative to the conventional process. Economic studies have been carried out to have a better understanding of the high costs and benefits of different technologies in the biodiesel industry. In this work it is studied the effect of the most important economic variables of a biodiesel production process over the general economy of a conventional plant which employs sodium methoxide as catalyst. It has been analyzed the effect of the oil price, the amount of free fatty acid, the biodiesel price, the cost of the glycerin, the effect due to the modification on the methanol price, the washing water price, and several others. Small variations on some of the major market variables would produce significant effects over the global economy of the plant, making it non profitable in some cases. © 2011 Elsevier Ltd. All rights reserved.

Singular features of trypanosomatids' phosphotransferases involved in cell energy management Pereira, Claudio Alejandro; Bouvier, León Alberto; Camara, María de los Milagros; Miranda, Mariana Reneé Trypanosomatids are responsible for economically important veterinary affections and severe human diseases. In Africa, Trypanosoma brucei causes sleeping sickness or African trypanosomiasis, while in America, Trypanosoma cruzi is the etiological agent of Chagas disease. These parasites have complex life cycles which involve a wide variety of environments with very different compositions, physicochemical properties, and availability of metabolites. As the environment changes there is a need to maintain the nucleoside homeostasis, requiring a quick and regulated response. Most of the enzymes required for energy management are phosphotransferases. These enzymes present a nitrogenous group or a phosphate as acceptors, and the most clear examples are arginine kinase, nucleoside diphosphate kinase, and adenylate kinase. Trypanosoma and Leishmania have the largest number of phosphotransferase isoforms ever found in a single cell; some of them are absent in mammals, suggesting that these enzymes are required in many cellular compartments associated to different biological processes. The presence of such number of phosphotransferases support the hypothesis of the existence of an intracellular enzymatic phosphotransfer network that communicates the spatially separated intracellular ATP consumption and production processes. All these unique features make phosphotransferases a promising start point for rational drug design for the treatment of human trypanosomiasis. © 2011 Claudio A. Pereira et al.

Characterization of the regulatory subunit of Yarrowia lipolytica cAMP-dependent protein kinase. Evidences of a monomeric protein Kronberg, Maria Florencia; Giacometti, Romina; Ruiz Herrera, Jose; Passeron, Susana cAMP-dependent protein kinase (PKA) catalytic (C) and regulatory (R) subunits from Yarrowia lipolytica are encoded by single genes, TPK1 and RKA1, respectively. Here we performed the heterologous expression, purification and characterization of the R subunit from Y. lipolytica yeast cells, and explored the main biochemical features of the PKA. The purified recombinant R, active and capable to interact with C subunit was used to prepare highly specific polyclonal antiserum. Sucrose-gradient centrifugation and gel filtration analysis of both recombinant and native R revealed the monomeric nature of this subunit. Hydrodynamic parameters of the holoenzyme indicated that Y. lipolytica PKA is a dimer of 90 kDa composed of an R subunit of 42 kDa and a C subunit of 39 kDa. The identification of the N-terminal sequence was carried out by mass spectrometry analysis of the purified native R subunit. The differences between N-terminal sequences of R subunits from Y. lipolytica and other organisms, particularly a short linker that spans the inhibitory site, were discussed as the possible cause of the lack of dimerization. R was identified as a type II subunit since our results indicated that it was phosphorylated in vivo by C at S124 identified by anti-phospho-PKA substrate (RRXS/T) antibody.

Hidrogenación de anhídrido maleico en fase gas sobre catalizadores soportados de Cu y Ni: efecto del soporte y del método de preparación Meyer, Camilo Ignacio; Regenhardt, Silvina Andrea; Bertone, Matías Ezequiel; Marchi, Alberto Julio; Garetto, Teresita Francisca Se estudió la hidrogenación de anhídrido maleico en fase gas empleando catalizadores de Cu y/o Ni, soportados sobre SiO2 y SiO2-Al2O3, preparados por impregnación a humedad incipiente y precipitación-deposición. La carga metálica total fue del orden del 10% en todos los casos. Las muestras fueron caracterizadas por DRX, RTP y quimisorción de H2. Los ensayos de actividad catalítica se llevaron a cabo en fase gas, a presión atmosférica y a temperaturas entre 170-220 ºC. Se encontró que tanto el método de preparación como el soporte influyen sobre las propiedades fisicoquímicas y la actividad catalítica de los sólidos preparados. Como consecuencia, es posible obtener catalizadores de Ni con diferente capacidad hidrogenolítica. Los catalizadores bimetálicos Cu-Ni resultaron más selectivos en la hidrogenólisis del anhídrido succínico a γ-butirolactona. Esto se atribuyo a la formación de una fase bimetálica de Cu-Ni, la cual se puede obtener más fácilmente por el método de precipitación-deposición.

Efectos de un programa de intervención para aumentar la reflexividad y la planificación en un ámbito escolar de alto riesgo por pobreza; Effects of a training program to increase reflexivity and planning in a school area at risk due to poverty Arán Filippetti, Vanessa; Richaud, Maria Cristina El propósito de este estudio fue analizar las diferencias en el estilo cognitivo reflexividad-impulsividad (R-I) y en la capacidad de planificación según el riesgo social, y poner a prueba la eficacia de un programa de intervención integrado a la tarea curricular áulica en un contexto de pobreza. Se trabajó con una muestra de 110 niños de 6 años de edad: experimental (N = 47) y control (N = 22) en riesgo por pobreza y un grupo control sin riesgo (N = 41) pertenecientes a Entre Ríos, Argentina. Los resultados indican claras diferencias en el patrón de respuestas R-I y en la planificación según el riesgo social, lo que apunta al papel de la experiencia en el desarrollo de estas funciones. Además brindan apoyo a la hipótesis que supone la posibilidad de aumentar la disposición reflexiva mediante un entrenamiento sistematizado.; The aim of this paper was to analyze the differences Reflexivity-Impulsivity in cognitive style and planning as regards social risk and to test the efficacy of a reflexivity training program integrated to the curriculum in a poverty context. We have worked with a sample of 110 6-year-old children: an experimental group (N = 47) a control group (N = 22) at risk and a control group not at risk (N = 41). All of them live in Entre Ríos, Argentina. The results indicate differences in R-I response patterns and planning in terms of social risk and emphasize the role of experience in the development of these functions. Besides, they support the hypothesis which holds the possibility to improve the reflexive disposition after program training.

Vibrio cholerae in waters of the Sunderban mangrove: relationship with biogeochemical parameters and chitin in seston size fractions Lara, Ruben Jose; Neogi, Sucharit B.; Islam, Mohammad Sirajul; Mahmud, Zahid H.; Islam, Shafiqul; Paul, Debasish; Demoz, Biniam; Yamasaki, Shinji; Nair, Gopinath B.; Kattner, Gerhard Wetland dynamics are probably linked to cholera endemicity in South Asia. We focus on links between Vibrio cholerae abundance, chitin content and suspended particle load in size fractions of suspended particulate matter (SPM) along the salinity gradient of Sunderban mangrove waters. SPM decreased downstream, while salinity increased from 0.2 to 4. Particulate organic carbon (90 ± 25 lM) and nitrogen (9.1 ± 3.3 lM) highly correlated with SPM and turbidity, suggesting a significant contribution of fine particles to organic matter. Total chitin ranged 1–2 mg/l and decreased downstream. The distribution among size fractions of SPM, chitin and V. cholerae O1 (the bacterial serogroup mainly associated with cholera epidemics) was similar, with *98% of the total in the fraction \20 lm. In comparison, the number of V. cholerae O1 attached to zooplankton and microplankton size classes [20 lm was almost negligible, in contrast to usual assumptions. Thus, microdetritus, nanoplankton and fungal cells in size classes \20 lm represent a chitinaceous substrate on which V. cholerae can grow and survive. Total bacteria, cultivable vibrios and V. cholera O1 increased 5–10 times downstream, together with salinity and nitrite concentration. Overall, nitrate and silicate concentrations were relatively constant ([22 lM N and 100 lM Si). However, nitrite increased *9 times in the outer sector, reaching *1.2 lM N, probably as a result of increased abundance of nitrate-reducing vibrios. A characterization of Vibrio habitats that takes account of the presence of nitrate-reducing bacteria could improve the understanding of both mangrove nitrogen cycling and cholera seasonality.

Can yield potential be increased by manipulation of reproductive partitioning in quinoa (Chenopodium quinoa)? Evidence from Gibberellic Acid synthesis inhibition using Paclobutrazol Gómez, María Belén; Aguirre Castro, P.; Mignone, C.; Bertero, Hector Daniel One factor conditioning quinoa (Chenopodium quinoa Willd.) adoption is the need to increase yield. This paper analyses the effect that Paclobutrazol, a GA synthesis inhibitor, produces on yield, biomass, partitioning, seed number and weight in quinoa. Two experiments were conducted under field conditions: one compared a tall genotype (2-Want) with a shorter genotype (NL-6); while the other analysed seed yield and its components using the 2-Want genotype. As a consequence of Paclobutrazol application in the one-genotype experiment, plant height decreased from 197 to 138 cm, yield increased from 517 to 791 g m–2, seed numbers rose from 308 000 to 432 000 seeds per m2, and the harvest index increased from 0.282 to 0.398 g g–1. Biomass accumulation and seed weight were not affected. The leaf area index was reduced by Paclobutrazol but radiation interception was only marginally reduced; soil plant analysis development (SPAD) values and specific leaf weight were increased, but radiation use efficiency was not affected by treatments. Root biomass and lateral roots tended to increase under Paclobutrazol treatment. Genotypes were compared until the end of flowering and similar responses were obtained. Higher yields could be obtained in quinoa if reproductive partitioning was increased, turning it into a good candidate in the search for high quality protein sources.

An extension of the Green-Ampt model to decreasing flooding depth conditions, with efficient dimensionless parametric solution Barrera, Daniel Florencio; Masuelli, Sergio The theoretical formulation of the Green-Ampt infiltration model has been extended to conditions of decreasing flooding depth in an isolated system. By defining dimensionless variables of flooding depth s and time τ, an implicit dimensionless equation τ(s) was obtained, which contains a single fundamental dimensionless parameter γ controlling the process, named “infiltration delay parameter”. The characteristics and functional behaviour of γ were analysed, and its physical meaning discussed. A parametric expression s(τ) has been obtained, which uses a unique descriptive parameter a, which in turn depends only on γ and on four generic coefficients valid for a wide range of soil properties and conditions occurring in nature. By means of numerical simulations using different values of soil parameters and initial flooding depths, it was proved that the proposed parametric function generates similar infiltration rates and cumulative storages to those that are obtained starting from Darcy's equation in the extended Green-Ampt scheme.

Diverse stages of sex-chromosome differentiation in tinamid birds: evidence from crossover analysis in Eudromia elegans and Crypturellus tataupa Pigozzi, Maria Ines All extant birds share the same sex-chromosome system: ZZ males and ZW females with striking differences in the stages of sex-chromosome differentiation between the primitive palaeognathus ratites and the large majority of avian species grouped within neognaths. Evolutionarily close to ratites is the neotropical order Tinamiformes that has been scarcely explored regarding their ZW pair morphology and constitution. Tinamous, when compared to ratites, constitute a large group among Palaeognathae, therefore, exploring the extent of homology between the Z and W chromosomes in this group might reveal key features on the evolution of the avian sex chromosomes. We mapped MLH1 foci that are crossover markers on pachytene bivalents to determine the size and localization of the homologous region shared by the Z and W chromosomes in two tinamous: Eudromia elegans and Crypturellus tataupa. We found that the homologous (pseudoautosomal) region differ significantly in size between these two species. They both have a single recombination event on the long arm of the acrocentric Z and W chromosomes. However, in E. elegans the pseudoautosomal region occupies one-fourth of the W chromosome, while in C. tataupa it is restricted to the tip of the long arm of the W. The W chromosomes in these two species differ in their heterochromatin content: in E. elegans it shows a terminal euchromatic segment and in C. tataupa is completely heterochromatic. These results show that tinamous have ZW pairs with more diversified stages of differentiation compared to ratites. Finally, the idea that the avian proto-sex chromosomes started to diverge from the end of the long arm towards the centromere of an acrocentric pair is discussed.

Vicenin-2, a potential anti-inflammatory constituent of Urtica circularis Marrassini, Carla; Davicino, Roberto Carlos; Acevedo, Cristina; Anesini, Claudia Alejandra; Gorzalczany, Susana; Ferraro, Graciela Ester Vicenin-2, a flavonoid glycoside, was isolated and identified from an ethanol extract of the aerial parts of Urtica circularis. This crude extract was found to possess significant anti-inflammatory activity in a carrageenan-induced rat hind paw edema model (41.5% inhibition at a dose of 300 mg/kg; ip). The effects of 1 on several inflammatory mediators were investigated. In cultured murine macrophages, this compound modified LPS-induced total nitrite and TNF-R production, in addition to the LPS-induced translocation of the nuclear factor NF-kB.

Ovarian steroid receptors and activated MAPK in the regional decidualization in rats Vallejo, Griselda; Mestre Citrinovitz, Ana Cecilia; Moenckendiek. Verena; Grümmer, Ruth; Winterhager, Elke; Saragueta, Patricia Esther Though the decidua serves a critical function in implantation, the hormonal regulated pathway in decidualization is still elusive. Here we describe in detail the regional distribution and the effects of progesterone receptors (PGR), estrogen receptors (ESR), and MAPK activation on decidualization. We showed an increase in PGR A, PGR B, ESR1, and phosphorylated MAPK3-1 proteins (p-MAPK3-1), but not in ESR2, in the decidual tissue up to Day 8 of pregnancy. PGR was predominantly found in the nuclei of mesometrial decidual cells and of undifferentiated stromal cells where it colocalizes with ESR2 and ESR1. In the antimesometrial decidua, all the receptors showed cytoplasmic localization. MAPK was activated exclusively in undifferentiated stromal cells of the junctional zone between the antimesometrial and mesometrial decidua and at the border of the antimesometrial decidua. Treatment with the progesterone antagonist onapristone and/or the estrogen antagonist faslodex reduced the extent of decidual tissue and downregulated the levels of PGR and ESR1. The expression level of ESR2 was affected only by the progesterone receptor antagonist, while neither the antiprogestin nor the antiestrogen significantly modified the p-MAPK3-1 level. The inhibition of MAPK3-1 phosphorylation by PD98059 impaired the extent of decidualization and the closure reaction of the implantation chamber, and significantly downregulated ESR1. These results confirm a role of both steroid receptors in the growth and differentiation of the different decidual regions and suggest a new function for p-MAPK3-1 in regulating expression levels of ESR1, thereby maintaining the proliferation capacity of stromal cells and limiting the differentiation process in specified regions of decidual tissues.

CTX-M-14 β-lactamase-producing Citrobacter freundii isolated in Venezuela Millan, Beatriz; Ghiglione, Barbara; Diaz, Tulia; Gutkind, Gabriel Osvaldo; Araque, María A clinical isolate of C. freundii with reduced susceptibility to extended-spectrum β-lactams from a woman with cystocele associated with recurrent urinary tract infection was analyzed. Susceptibility tests, double disk synergy tests (DDST) and enzymatic activity by the agar iodometric method suggested the presence of ESBLs. Conjugation experiments revealed the presence of a large conjugative plasmid (pLM07/20) with an exclusive FrepB replicon type (IncF/FIB). PCR analysis and sequencing confirmed the presence of the blaCTX-M-14 gene in the pLM07/20 from C. freundii.LM07/10. Although this is the first report of CTX-M-14 in Venezuela, we alert the medical community that future increase of these β-lactamases in our city could be due to dissemination of plasmids into bacterial populations.

Visualization and quantification of cytotoxicity mediated by antibodies using imaging flow cytometry Helguera, Gustavo Fernando; Rodríguez, José A.; Luria Pérez, Rosendo; Henery, Shannon; Catterton, Paul; Bregni, Carlos ; George, Thaddeus C.; Martínez Maza, Otoniel; Penichet, Manuel L. Conventional approaches for the detection of antibody dependent cell-mediated cytotoxicity (ADCC) activity rely on quantification of the release of traceable compounds from target cells or flow cytometry analysis of population-wide phenomena. We report a new method for the direct imaging and quantification of ADCC of cancer cells. The proposed method using imaging flow cytometry combines the statistical power of flow cytometry with the analytical advantages of cell imaging, providing a novel and more comprehensive perspective of effector/target cell interactions during ADCC events. With this method we can quantify and show in detail the morphological changes in target and effector cells, their apoptotic index, the physical interaction between effector and target cells, and a directional transfer of cytosolic contents from effector to target cells. As a model system we used the therapeutic anti-CD20 antibody rituximab to target CFSE labeled Ramos human Burkitt's lymphoma cells, to CMTPX-labeled human monocytic U-937 effector cells. We expect that similar studies using different effector and target cell populations may contribute to the pre-clinical evaluation of therapeutic antibodies and help to identify mechanisms that could be beneficial in the immunotherapy of cancer.

A new species and new records of Cercophora from Argentina Catania, Myriam del Valle; Romero, Andrea Irene; Huhndorf, Sabine M.; Miller, Andrew N. Three species of Cercophora were found during a survey of the biodiversity of microfungi in northwest Argentina. Cercophora argentina possesses a unique combination of morphological characters and is described as a new species, while C. costaricensis and C. solaris are reported as new records for Argentina. Other species of Cercophora known from this region include C. natalita and C. coprogena, which is fully illustrated for the first time and determined herein to be a synonym of C. californica. All other species are described and illustrated.

Elevo a la superioridad: Un estado de la cuestión sobre la historia de los inspectores en Argentina Southwell, Myriam Monica; Manzione, Gregoria Maria Ana Este artículo se propone sistematizar la investigación existente sobre los inspectores escolares en Argentina. Nos interesa en este punto tratar de poner a disposición algunas notas preliminares para una historia de la inspección a nivel nacional. Para ello, examinaremos esa tarea en relación con tres tensiones que animaron esas estructuras e instituciones: la cuestión federal, la relación entre estado y sociedad civil y la diferenciación entre un saber burocrático y un saber pedagógico. Asimismo, nos proponemos contribuir con el debate que algunos de los trabajos previos han planteado acerca de si la tarea de la inspección fue desarrollada en términos de la vigilancia y prescripción de las políticas centrales o si esos roles fueron ejercidos junto con un carácter más autónomo y creativo según el propio criterio profesional.; The article focuses on a systematization of previous investigations on school inspectors in Argentina. Our aim is to point out some notes and referencies in order to contribute for a history of inspectors in our country. This analysis involves three central topics related to inspectors task: federal question, relation between state and civil society and a diferentiation between bureaucratic and pedagogical knowledge. Moreover, we want to contribute in a existing debate about inspectors 'actions was only a result of application of central policies, control and prescription or its practices had also a significant creative and autonomous character.

Inhibitory effects of ghrelin on sexual behavior: Role of the peptide in the receptivity reduction induced by food restriction in mice Bertoldi, María Laura; Luque, E. M.; Carlini, Valeria Paola; Vincenti, Laura María; Stutz, Graciela; Santillán, M.E.; Ruiz, R. D.; Fiol de Cuneo, Marta; Martini, Ana Carolina Ghrelin (Ghr) is a gut/hypothalamus peptide with inhibitory actions on reproductive physiology; however, there are no previous reports of its role on estrous behavior. Under the hypothesis that the increase of plasma Ghr during food restriction (FR) is responsible for receptivity reduction, we intended to evaluate the receptivity percentage of female mice subjected to: exp. 1) acute and chronic FR and Ghr administration (3 nmol/animal/day, s. c.) and exp. 2) the co-administration of a ghrelin antagonist [ant=(d-Lys3)-GHRP-6; 6 nmol/animal/day s. c.]. All females were ovariectomized, primed with steroids, trained, and randomly subjected every week to each one of several protocols, followed by a behavioral test. Experiment 1 (n=8): basal, no treatment; acute FR (aFR), 24-h fasting; chronic FR (cFR), 50% FR for 5 days; acute ghrelin (aGhr), Ghr 30 min before test and chronic ghrelin (cGhr), Ghr for 5 days. Except for cGhr, all treatments significantly decreased the percentage of receptivity (mean±SEM): basal 61.9±6.0, aFR 33.1±8.1, cFR 18.8±7.7, aGhr 45.6±10.6, p<0.05 vs. basal. In exp. 2 (n=11), except for cFR+ant (55.0±6.4) the co-administration of the antagonist reversed the deleterious effects detected in exp. 1: basal 70.9±5.4; aFR+ant 72.3±7.6; aGhr+ant 73.6±4.7. As expected, the administration of vehicle or antagonist alone did not modify receptivity. Besides, we found a significant correlation between percentage of body weight loss and percentage of receptivity reduction (r=0.62, p=0.0004). This is the first study demonstrating that ghrelin is able to inhibit female mice sexual behavior and that is involved, at least in part, in receptivity reduction after food scarcity.

¿Qué nos enseñan los 20 años del Mercosur? Botto, Mercedes Isabel A 20 años de la puesta en marcha del Mercosur, no solamente se amplió el número de sus integrantes, sino que asistimos a cambios políticos e ideológicos en los países miembros. Si la piedra fundamental de la integración fue colocada en un contexto de hegemonía neoliberal, hoy se exploran otras vías, en las que se asigna al Estado un rol inevitable en el desarrollo. En ese marco, en la reunión de Córdoba de 2006, se lanzó la etapa del «Mercosur Social y Productivo», que procura revertir el desencanto de un proceso con excesivo énfasis en las políticas comerciales y con muchas debilidades en áreas como educación, integración productiva y políticas medioambientales.; Twenty years since the launch of Mercosur, not only has the number of members grown, but we have also witnessed political and ideological changes in member states. If the fundamental pillar of integration was laid in a hegemonic neoliberal context, today other paths have been explored, in which the State has been given the inevitable role of development. As a result, at the 2006 summit in Córdoba the «Social and Productive Mercosur» stage was launched, which endeavours to revert the disenchantment in a process with excessive emphasis in commercial policies and with a great deal of weakness in areas like education, productive integration and environmental policies.

Normas permisivas y clausura de los sistemas normativos Navarro, Pablo Eugenio En este trabajo analizo la autonomía y relevancia normativa de las normas permisivas. En especial, mis propósitos principales son revisar dos tesis escépticas: (i) los permisos y las normas permisivas pueden reducirse a otras formas normativas, e.g. derogación de prohibiciones, y (ii) no se producen diferencias significativas cuando se permite una conducta que no había sido previamente regulada. Ambas tesis son examinadas en relación a la naturaleza y función del principio de clausura normativa (todo lo que no está prohibido está permitido). La conclusión de este trabajo es que las normas permisivas, y en particular las normas de clausura, pueden cumplir una importante función en los sistemas normativos y son una herramienta útil para analizar otros problemas como las lagunas del derecho y la discreción judicial.