Evaluation of glutamate excitotoxicity induced by dengue virus neuroadapted D4MB -6

El virus de dengue (DENV), a pesar de ser clasificado como un virus no neurotrópico, induce durante la infección manifestaciones neurológicas como la alteración de la conciencia. Hasta el momento, los signos y síntomas neurológicos que aparecen durante la infección por DENV no se han asociado a un mecanismo en particular. Durante la infección con el JEV, WNV y el HIV se produce la disfunción y muerte de neuronas mediada por procesos excitatorios. Para Dengue, hasta el momento sólo se ha reportado en modelos in vivo e in vitro y en muestras post-mortem el daño del tejido y la perdida neuronal, sin embargo no se conoce si durante la infección con este virus suceden eventos excitotoxicos o si la la exacerbada respuesta inmune afecta la superviviencia neuronal En el presente estudio se planteó -utilizando el modelo de neuroinfección desarollado en nuestro laboratorio-, evaluar las posibles causas de alteración y muerte neuronal inducidas por la cepa D4MB-6 y el efecto de dos fármacos, ácido valproico (VPA) y MK-801 con el fin de. Para esto, se infectaron ratones Balb/C de 7 dpn con el D4MB-6 tratados o no tratados con VPA o MK 801. Los animales fueron observados y pesados diariamente por 3 o 6 dpi y sacrificados para la extracción del encéfalo y médula. De estos tejidos se obtuvieron homogenizados o cortes histológicos para evaluar la infección y producción viral, la morfología, la expresión de algunas proteínas pro y anti-apoptóticos. En los animales infectados no tratados, las manifestaciones clínicas fueron evidentes al 3er dpi y severas al 6to dpi, al igual que las alteraciones histológicas, caracterizadas por apoptosis, necrosis y espongiosis neuronal acompañadas de alteraciones vasculares como hemorragias, edema e infiltrado de células mononucleares. En esta misma, condición se observó astrogliosis, neurodegeneración y aumento en la expresión de proteínas pro-apoptóticas, como Casp 3, 8, y Bax. Por el contrario, en los animales infectados y tratados todas las manifestaciones y alteraciones neurológicas fueron reducidas, detectando sólo algunas células en apoptosis y neurodegeneración en el cerebelo de animales infectados y tratados con VPA y MK 801, al igual que la producción y transcritos pro- apoptóticos. Estos resultados sugieren que el virus D4MB-6 induce encefalitis y mielitis, como alteración vascular, así como muerte neuronal mediada por procesos excitotóxicos e inmunológicos. Dichas alteraciones son prevenidas de forma total o parcial con los fármacos MK 801 y VPA.Magíster en Ciencias Básicas BiomédicasMaestríaThe dengue virus (DENV), despite being classified as a non-neurotropic virus during infection induces neurological symptoms such as impaired consciousness. So far, the neurological signs and symptoms that appear during DENV infection have not been associated to a particular mechanism. During infection with JEV, WNV and HIV dysfunction and neuronal death mediated excitatory process occurs. Dengue, so far only been reported in in vivo and in vitro models and samples postmortem tissue damage and neuronal loss, however not known whether during infection with this virus occur excitotoxic events or the exacerbated immune response affects neuronal survival. In the present study it raised -using neuroinfection model developed in our laboratory-, so evaluate potential causes of impairment and neuronal death induced D4MB-6 strain and the effect of two drugs, valproic acid (VPA) and MK 801. For this, Balb/C mice were infected with D4MB-6 treated or not treated with VPA or MK 801. The animals were observed and weighed daily for 3 or 6 dpi and sacrificed for the removal of the brain and spinal cord. These tissues homogenates or tissue sections to assess viral infection and production, morphology, expression of some pro and anti-apoptotic proteins were obtained. In infected untreated animals, the clinical manifestations were evident to 3rd and severe to the 6th dpi, as well as histological alterations, characterized by apoptosis, neuronal necrosis and spongiosis accompanied by vascular disorders such as bleeding, edema and infiltration of mononuclear cells. In the same, astrogliosis condition, neurodegeneration and increased expression of pro-apoptotic proteins such as Casp3, 8, and Bax it was observed. Conversely, infected and treated at all manifestations and neurological disorders animals were reduced by detecting only a few cells in apoptosis and neurodegeneration in the cerebellum of infected and treated with VPA and MK 801 animals, as the production and transcribed pro- apoptotic. These results suggest that the D4MB-6 virus induces encephalitis and myelitis, and vascular changes and mediated excitotoxic neuronal death and immunological processes. Such alterations are prevented in whole or in part with the MK 801 and VPA drug

Indo-Eroticism in “Las mareas vuelven de noche,” by Yolanda Oreamuno

Este estudio se refiere al tema del erotismo oriental (el de India), en «Las mareas vuelven de noche», de la escritora costarricense Yolanda Oreamuno. El cuento relata el encuentro entre una mujer oriental y un hombre occidental, que trata la experiencia de erotismo ligado al contexto indio. Se analiza la fusión entre los amantes en un solo ser que intenta la trascendencia; en el relato, el erotismo está constituido por escenarios palpables a través de los sentidos que refuerzan el carácter espiritual, etéreo y divinizante de la unión amorosa.This study explores Oriental eroticism in “Las mareas vuelven de noche,” by the Costa Rican author Yolanda Oreamuno. This short story narrates an encounter between an oriental woman and an occidental man, addressing the experience of eroticism in India. The text proposes the union of the lovers as transcendental act. In the narration, eroticism is viewed in different scenes drawn by the senses strengthening the spiritual, divine-like and ethereal atmosphere of coming together in love.UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Sociales::Instituto de Investigaciones Psicológicas (IIP

Approaching a Definition of the Costa Rican Neo-Detective Novel

Por sus características, las obras Mariposas negras para un asesino (2005) y El laberinto del verdugo (2010), de Jorge Méndez Limbrick, se acercan a la condición de novela neopolicial costarricense, inscrita en lo neopolicial centroamericano. Se analiza la relación de esas obras con el género. Se propone una serie de cualidades, tales como la construcción de personajes completos, la exposición del realismo crudo y la presencia de la noche como elemento trascendental para el surgimiento del crimen, como base de un género que se empieza a definir y a difundir en la narrativa costarricense.Mariposas negras para un asesino (2005) and El laberinto del verdugo (2010), by Jorge Méndez Limbrick, come close to the condition of a Costa Rican neo-detective novel, within the Central American neo-detective framework. The relationship of these novels with that genre will be analyzed. A series of qualities will be proposed, such as the construction of complete characters, the exposure of crude realism and the presence of the night as a transcendental element for the emergence of crime, as the basis of a genre that is beginning to be defined and spread in the Costa Rican narrative.UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Sociales::Instituto de Investigaciones Psicológicas (IIP

La infección con el virus del dengue induce apoptosis en células del neuroblastoma humano SH-SY5Y

Introduction: Dengue is a human disease caused by a virus with the same name, which is transmitted by the bite of Aedes mosquitoes. The infection has a wide range of clinical presentations ranging from asymptomatic to fatal cases, with the pediatric population being the most susceptible. According to the new classification of the disease, the neurological manifestations are considered a criterion for the diagnosis of severe dengue. Objective: To evaluate the possible mechanisms involved in the onset of neurological signs in a cell line of human neurons as a model of infection with dengue virus type 2 (DENV-2). Materials and methods: Susceptibility and permissiveness of the SH-SY5Y line to infection by DENV-2 was analyzed, showing that the proportions of viral infection and production are similar to those of primate cells used as positive control for infection. Results: Infection induced a cytopathic effect on the neuroblastoma line characterized by apoptotic cell death process, increasing the proportion of annexin V and TUNEL positive cells and an upregulation of TNF-α. Treatment with anti-TNF-α antibody increased slightly cell survival of infected cells. The addition of exogenous TNF-α to the infected cultures enhanced cell death. Conclusion: These results as a whole suggest that the upregulation of TNF-α could be part of the process that induces cell damage and death in cases of dengue encephalitis.Introducción. El dengue es una enfermedad humana producida por el virus del mismo nombre, que se transmite por la picadura de mosquitos del género Aedes. La infección tiene una amplia gama de presentaciones clínicas que van desde la ausencia de síntomas hasta los casos fatales y afecta principalmente a la población pediátrica. Según la nueva clasificación de la enfermedad, las manifestaciones neurológicas se consideran un criterio para el diagnóstico del dengue grave.Objetivo. Evaluar los posibles mecanismos involucrados en la aparición de los signos neurológicos en una línea celular de neuronas humanas, como modelo de infección con el virus del dengue del serotipo 2 (DENV-2).Materiales y métodos. Se evaluó la sensibilidad y la permisividad de la línea celular SH-SY5Y a la infección por el DENV-2; se encontró que la proporción entre infección y producción viral era similar a las de las células de primates usadas como control positivo de la infección.Resultados. La infección indujo un efecto citopático en la línea celular de neuroblastoma caracterizado por un proceso de muerte apoptótica, con aumento en la proporción de células positivas al emplear los métodos de anexina V y TUNEL. Se encontró una regulación positiva del factor de necrosis tumoral alfa (TNF-α), y el tratamiento con un anticuerpo anti-TNF-α aumentó ligeramente la supervivencia de las células infectadas. La adición de TNF-α exógeno a los cultivos infectados potenció la muerte celular.Conclusión. Estos resultados sugieren, en su conjunto, que la regulación positiva del TNF-α podría hacer parte del proceso que induce daño y muerte celular durante el desarrollo de la encefalitis por dengue

A case series of severe dengue with neurological presentation in children from a colombian hyperendemic area

Dengue transmission is sustained in Colombia with increasing prevalence mainly in children. This work aimed to describe a case series of children diagnosed with dengue presenting neurological disease in Huila Province of Colombia. Eleven pediatric febrile patients confirmed for dengue disease and presenting neurological signs were studied in the University Hospital of Neiva, Huila Province. Clinical and laboratory findings, CSF cytochemical analysis, neurology images, and serology and molecular studies were performed. Viral RNA was detected in all patients' sera by RT-PCR. Nine out of 11 were primary infections. Tonic-clonic seizures (73%), consciousness alterations (27%), irritability (27%), and ataxia (18%) were the most frequent neurological signs. None of the patients had plasma leakage, hypovolemic shock, or liver disease, confirming the encephalitis diagnosis. Diagnostic images did not show abnormal findings, but neither bacterial nor fungal infections were detected in CSF analysis. All patients survived without sequelae except for one patient that presented ataxia for months. In conclusion, we described a group of children with neurological signs during severe dengue disease as the main finding, indicating the importance to including dengue as a differential diagnosis in neurological patients from endemic areas.Dengue transmission is sustained in Colombia with increasing prevalence mainly in children. This work aimed to describe a case series of children diagnosed with dengue presenting neurological disease in Huila Province of Colombia. Eleven pediatric febrile patients confirmed for dengue disease and presenting neurological signs were studied in the University Hospital of Neiva, Huila Province. Clinical and laboratory findings, CSF cytochemical analysis, neurology images, and serology and molecular studies were performed. Viral RNA was detected in all patients' sera by RT-PCR. Nine out of 11 were primary infections. Tonic-clonic seizures (73%), consciousness alterations (27%), irritability (27%), and ataxia (18%) were the most frequent neurological signs. None of the patients had plasma leakage, hypovolemic shock, or liver disease, confirming the encephalitis diagnosis. Diagnostic images did not show abnormal findings, but neither bacterial nor fungal infections were detected in CSF analysis. All patients survived without sequelae except for one patient that presented ataxia for months. In conclusion, we described a group of children with neurological signs during severe dengue disease as the main finding, indicating the importance to including dengue as a differential diagnosis in neurological patients from endemic areas

Dengue virus infection of blood-brain barrier cells: consequences of severe disease

More than 500 million people worldwide are infected each year by any of the four-dengue virus (DENV) serotypes. The clinical spectrum caused during these infections is wide and some patients may develop neurological alterations during or after the infection, which could be explained by the cryptic neurotropic and neurovirulent features of flaviviruses like DENV. Using in vivo and in vitro models, researchers have demonstrated that DENV can affect the cells from the blood–brain barrier (BBB) in several ways, which could result in brain tissue damage, neuronal loss, glial activation, tissue inflammation and hemorrhages. The latter suggests that BBB may be compromised during infection; however, it is not clear whether the damage is due to the infection per se or to the local and/or systemic inflammatory response established or activated by the BBB cells. Similarly, the kinetics and cascade of events that trigger tissue damage, and the cells that initiate it, are unknown. This review presents evidence of the BBB cell infection with DENV and the response established toward it by these cells; it also describes the consequences of this response on the nervous tissue, compares these evidence with the one reported with neurotropic viruses of the Flaviviridae family, and shows the complexity and unpredictability of dengue and the neurological alterations induced by it. Clinical evidence and in vitro and in vivo models suggest that this virus uses the bloodstream to enter nerve tissue where it infects the different cells of the neurovascular unit. Each of the cell populations respond individually and collectively and control infection and inflammation, in other cases this response exacerbates the damage leaving irreversible sequelae or causing death. This information will allow us to understand more about the complex disease known as dengue, and its impact on a specialized and delicate tissue like is the nervous tissue

Nuclei ultrastructural changes of C6/36 cells infected with virus dengue type 2

Introduction: Dengue virus replication has been considered mainly cytoplasmic, however, studies indicate that some flaviviruses may use the intranuclear pathway as part of the machinery that the virus uses to increase infection capacity in the host cell. This paper describes alterations at nuclear level in the cell infected with dengue, which are likely involved in the virus replication processes. Objective: This paper addresses the ultrastructural observations of C6/36 cells of the Aedes albopictus mosquito infected with dengue virus type 2. Materials and methods: C6/36 cells were infected in culture medium with the serum of a patient positively diagnosed for dengue 2. Subsequently, the cells were incubated for 10 days and the cytopathic effect was assessed. The cells were processed for immunofluorescence assays and transmission electron microscopy. Results: The immunofluorescence assays confirmed the presence of viral protein E associated with cellular syncytia in the culture. In the ultrastructural study, the infected cells showed vesicular-tubular structures and dilated cisterns of the endoplasmic reticulum at the cytoplasmic level. Viral particles were found exclusively in cytoplasm localized within the vacuoles. Nuclei of cellular syncytia showed membrane structures arranged in a circular shape and, in some cases, these syncytia displayed lysis; in no case viral particles were observed at the nuclear level. Conclusions: The ultrastructural alterations of nuclei in cells infected with the dengue virus using electron microscopy techniques had not been reported before, as far as we know. It is likely that such modifications are associated with replicative processes at an intranuclear level as an alternate replication mechanism

Temperature Effects Explain Continental Scale Distribution of Cyanobacterial Toxins

Insight into how environmental change determines the production and distribution of cyanobacterial toxins is necessary for risk assessment. Management guidelines currently focus on hepatotoxins (microcystins). Increasing attention is given to other classes, such as neurotoxins (e.g., anatoxin-a) and cytotoxins (e.g., cylindrospermopsin) due to their potency. Most studies examine the relationship between individual toxin variants and environmental factors, such as nutrients, temperature and light. In summer 2015, we collected samples across Europe to investigate the effect of nutrient and temperature gradients on the variability of toxin production at a continental scale. Direct and indirect effects of temperature were the main drivers of the spatial distribution in the toxins produced by the cyanobacterial community, the toxin concentrations and toxin quota. Generalized linear models showed that a Toxin Diversity Index (TDI) increased with latitude, while it decreased with water stability. Increases in TDI were explained through a significant increase in toxin variants such as MC-YR, anatoxin and cylindrospermopsin, accompanied by a decreasing presence of MC-LR. While global warming continues, the direct and indirect effects of increased lake temperatures will drive changes in the distribution of cyanobacterial toxins in Europe, potentially promoting selection of a few highly toxic species or strains.Peer reviewe

Estudios actuales de literatura comparada. Teorías de la literatura y diálogos interdisciplinarios

Estos dos volúmenes constituyen una contribución al desarrollo de la comparatística que se realiza, principalmente, desde América Latina. El primer volumen está organizado en tres partes y consta de 22 artículos, mientras que el segundo reúne 24 capítulos.UCR::Vicerrectoría de Docencia::Artes y Letras::Facultad de Letras::Escuela de Filología, Lingüística y LiteraturaUCR::Vicerrectoría de Docencia::Ciencias Básicas::Sistema de Educación General::Escuela de Estudios GeneralesUCR::Vicerrectoría de Investigación::Sistema de Estudios de Posgrado::Artes y Letras::Maestría Académica en Literatura FrancesaUCR::Vicerrectoría de Investigación::Sistema de Estudios de Posgrado::Artes y Letras::Maestría Académica en Literatura LatinoamericanaUCR::Vicerrectoría de Docencia::Artes y Letras::Facultad de Letras::Escuela de Lenguas Moderna

Erotismo indio en «Las mareas vuelven de noche», de Yolanda Oreamuno

Este estudio se refiere al tema del erotismo oriental (el de India), en «Las mareas vuelven de noche», de la escritora costarricense Yolanda Oreamuno. El cuento relata el encuentro entre una mujer oriental y un hombre occidental, que trata la experiencia de erotismo ligado al contexto indio. Se analiza la fusión entre los amantes en un solo ser que intenta la trascendencia; en el relato, el erotismo está constituido por escenarios palpables a través de los sentidos que refuerzan el carácter espiritual, etéreo y divinizante de la unión amorosa