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Search Results: 1 - 10 of 239837 matches for " Juan Carlos de la Torre "
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Arenavirus Budding
Shuzo Urata,Juan Carlos de la Torre
Advances in Virology , 2011, DOI: 10.1155/2011/180326
Abstract: Several arenaviruses cause hemorrhagic fever disease in humans and pose a significant public health concern in their endemic regions. On the other hand, the prototypic arenavirus LCMV is a superb workhorse for the investigation of virus-host interactions and associated disease. The arenavirus small RING finger protein called Z has been shown to be the main driving force of virus budding. The budding activity of Z is mediated by late (L) domain motifs, PT/SAP, and PPXY, located at the C-terminus of Z. This paper will present the current knowledge on arenavirus budding including the diversity of L domain motifs used by different arenaviruses. We will also discuss how improved knowledge of arenavirus budding may facilitate the development of novel antiviral strategies to combat human pathogenic arenaviruses. 1. Introduction Arenaviruses are enveloped viruses with a bisegmented negative strand (NS) RNA genome with coding capability for four known genes: nucleoprotein (NP), surface glycoprotein precursor (GPC), polymerase (L), and matrix-like (Z) proteins. Despite their limited genome and proteomic complexity, arenaviruses are able to exhibit very different phenotypic infection outcomes ranging from long-term subclinical chronic infections on their natural rodent hosts [1] to hemorrhagic fever (HF) disease in humans, infected through mucosal exposure to aerosols or by direct contact of abrade skin with infectious material. Thus, Lassa virus (LASV), the causative agent of Lassa fever (LF) is estimated to infect several hundred thousand individuals yearly in its endemic regions of West Africa, resulting in a high number of LF cases associated with high morbidity and significant mortality. Likewise, Junin virus (JUNV) causes Argentine HF, a severe illness with hemorrhagic and neurological manifestations and a case fatality of 15–30%, whereas the Machupo (MACV) and Guanarito (GTOV) arenaviruses emerged as causative agents of HF in Bolivia and Venezuela, respectively. On the other hand, the prototypic arenavirus, lymphocytic choriomeningitis virus (LCMV), is a superb workhorse for the investigation of virus-host interactions including mechanisms of virus control and clearance by the host immune defenses, as well as viral counteracting measures leading to chronic infection and associated disease [2, 3]. Moreover, evidence indicates that the globally distributed prototypic arenavirus LCMV is a neglected human pathogen of clinical significance, especially in cases of congenital infection. In addition, LCMV poses a special threat to immunocompromised individuals, as
Inhibition of the Type I Interferon Antiviral Response During Arenavirus Infection
Persephone Borrow,Luis Martínez-Sobrido,Juan Carlos De la Torre
Viruses , 2010, DOI: 10.3390/v2112443
Abstract: Arenaviruses merit interest both as tractable experimental model systems to study acute and persistent viral infections, and as clinically-important human pathogens. Several arenaviruses cause hemorrhagic fever (HF) disease in humans. In addition, evidence indicates that the globally-distributed prototypic arenavirus lymphocytic choriomeningitis virus (LCMV) is a human pathogen of clinical significance in congenital infections, and also poses a great danger to immunosuppressed individuals. Arenavirus persistence and pathogenesis are facilitated by their ability to overcome the host innate immune response. Mammalian hosts have developed both membrane toll-like receptors (TLR) and cytoplasmic pattern recognition receptors (PRRs) that recognize specific pathogen-associated molecular patterns (PAMPs), resulting in activation of the transcription factors IRF3 or IRF7, or both, which together with NF-κB and ATF-2/c-JUN induce production of type I interferon (IFN-I). IFN-I plays a key role in host anti-microbial defense by mediating direct antiviral effects via up-regulation of IFN-I stimulated genes (ISGs), activating dendritic cells (DCs) and natural killer (NK) cells, and promoting the induction of adaptive responses. Accordingly, viruses have developed a plethora of strategies to disrupt the IFN-I mediated antiviral defenses of the host, and the viral gene products responsible for these disruptions are often major virulence determinants.IRF3- and IRF7-dependent induction of host innate immune responses is frequently targeted by viruses. Thus, the arenavirus nucleoprotein (NP) was shown to inhibit the IFN?I response by interfering with the activation of IRF3. This NP anti-IFN activity, together with alterations in the number and function of DCs observed in mice chronically infected with LCMV, likely play an important role in LCMV persistence in its murine host. In this review we will discuss current knowledge about the cellular and molecular mechanisms by which arenaviruses can subvert the host innate immune response and their implications for understanding HF arenaviral disease as well as arenavirus persistence in their natural hosts.
Mixomas cardíacos: un acercamiento a una rara afección Cardiac myxomas: a close view towards a rare infection
Carlos Alberto de la Torre Fonseca,Juan Castellanos Tardo,Jorge Carlos Machín Rodríguez,Fredy Torralbas Reverón
MEDISAN , 2011,
Abstract: Según lo informado en la bibliografía médica, los tumores cardíacos y en particular los mixomas son raros; sin embargo, constituyen afecciones de interés e importancia no solo entre las cardiovasculares, sino también entre las entidades clínicas en general. Esta afirmación se sustenta en el hecho de que pueden simular las más diversas enfermedades cardíacas o enmascararse como colagenosis, sepsis generalizadas, neoplasias malignas, alteraciones arteriales periféricas u otros procesos morbosos. En Cuba se ha publicado muy poco en torno al tema y esa escasez al respecto motivó a los autores a presentar en este artículo de revisión una clasificación actualizada de los mixomas cardíacos, con especial referencia a su anatomía patológica, factores genéticos, síntomas más frecuentes, métodos para su diagnóstico clínico y bases fundamentales para el tratamiento quirúrgico. Cardiac tumors, particularly myxomas, are rare according to the literature reported. They constitute not only cardiovascular diseases of interest and importance, but also conditions that call the attention among clinical affections in general terms. This statement supports the fact that they can simulate the most diverse heart diseases or mask as collagenosis, generalized sepsis, malignancies, peripheral artery diseases or some other morbid conditions. In Cuba, very little literature has been published about this topic. That is why the authors of this review article decided to make a presentation of an updated cardiac myxoma classification, emphasizing its pathology, genetic factors, most common symptoms, diagnostic methods, and primary basis for the surgical treatment.
Tratamiento quirúrgico de los mixomas cardíacos: Primera serie de la región oriental de Cuba Surgical treatment of heart myxomas: First series in the eastern region of Cuba
Carlos Alberto de la Torre Fonseca,Juan Castellanos Tardo,Jorge Carlos Machín Rodríguez,Fredy Torralbas Reverón
MEDISAN , 2010,
Abstract: Se realizó un estudio descriptivo y transversal de los 38 pacientes operados en el Cardiocentro de Santiago de Cuba con el diagnóstico de mixoma cardíaco, desde 1986 hasta 2010, con vista a identificar las principales características del tratamiento quirúrgico en la serie. Entre los resultados terapéuticos sobresalieron: el acceso quirúrgico por biatriotomía transeptal, la cardioplejia cristaloide hipotérmica, con tiempos de pinzamiento aórtico y derivación cardiopulmonar por debajo de la media internacional, además de las arritmias supraventriculares como complicaciones más comunes. La evolución posoperatoria fue favorable y la mortalidad baja, lo cual avala la seguridad del procedimiento aplicado. A descriptive and cross-sectional study was conducted in 38 patients operated at the Cardiology Center of Santiago de Cuba with the diagnosis of heart myxoma, from 1986 to 2010, in order to identify the main characteristics of surgical treatment in the series. Among therapeutic results were surgical approach through transeptal biatriotomy, hypothermal crystalloid cardioplegia, with times of aortic clipping and cardiopulmonary derivation below the international average besides supraventricular arrhythmias as the most common complications. Postoperative course was favorable and mortality was low, which guarantees the safety of the applied procedure.
Aspectos clínicos de los mixomas cardíacos. Primera serie de la región oriental de Cuba Clinical aspects of cardiac myxomas. First series of the Cuban eastern region
Juan Castellanos Tardo,Carlos Alberto de la Torre Fonseca,Jorge Carlos Machín Rodríguez,Fredy Torralbas Reverón
MEDISAN , 2010,
Abstract: Se realizó un estudio descriptivo y transversal de los 38 pacientes operados en el Cardiocentro de Santiago de Cuba desde 1986 hasta 2010 con el diagnóstico de mixoma cardíaco para identificar, desde el punto de vista clínico, las principales características de la casuística. Los signos de obstrucción auricular izquierda fueron, casi en su totalidad, los causantes de las manifestaciones clínicas y de los hallazgos más comunes de la afección en el examen físico. Los plops tumorales y los cambios posturales de intensidad de los soplos y ruidos cardíacos resultaron ser elementos de cierto valor para el diagnóstico de esta cardiopatía. A descriptive and cross-sectional study was conducted in 38 patients operated in the Cardiology Center of Santiago de Cuba from 1986 to 2010 with the diagnosis of cardiac myxoma to identify from the clinical point of view the main characteristics of the case material. Signs of left atrial obstruction were, almost entirely, the cause of clinical manifestations and the most common findings of the disease on physical examination. Tumor plops and postural changes of intensity of murmurs and heart sounds were elements of some value for the diagnosis of this heart disease.
Mutagenesis-Mediated Virus Extinction: Virus-Dependent Effect of Viral Load on Sensitivity to Lethal Defection
Héctor Moreno, Héctor Tejero, Juan Carlos de la Torre, Esteban Domingo, Verónica Martín
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0032550
Abstract: Background Lethal mutagenesis is a transition towards virus extinction mediated by enhanced mutation rates during viral genome replication, and it is currently under investigation as a potential new antiviral strategy. Viral load and virus fitness are known to influence virus extinction. Here we examine the effect or the multiplicity of infection (MOI) on progeny production of several RNA viruses under enhanced mutagenesis. Results The effect of the mutagenic base analogue 5-fluorouracil (FU) on the replication of the arenavirus lymphocytic choriomeningitis virus (LCMV) can result either in inhibition of progeny production and virus extinction in infections carried out at low multiplicity of infection (MOI), or in a moderate titer decrease without extinction at high MOI. The effect of the MOI is similar for LCMV and vesicular stomatitis virus (VSV), but minimal or absent for the picornaviruses foot-and-mouth disease virus (FMDV) and encephalomyocarditis virus (EMCV). The increase in mutation frequency and Shannon entropy (mutant spectrum complexity) as a result of virus passage in the presence of FU was more accentuated at low MOI for LCMV and VSV, and at high MOI for FMDV and EMCV. We present an extension of the lethal defection model that agrees with the experimental results. Conclusions (i) Low infecting load favoured the extinction of negative strand viruses, LCMV or VSV, with an increase of mutant spectrum complexity. (ii) This behaviour is not observed in RNA positive strand viruses, FMDV or EMCV. (iii) The accumulation of defector genomes may underlie the MOI-dependent behaviour. (iv) LCMV coinfections are allowed but superinfection is strongly restricted in BHK-21 cells. (v) The dissimilar effects of the MOI on the efficiency of mutagenic-based extinction of different RNA viruses can have implications for the design of antiviral protocols based on lethal mutagenesis, presently under development.
Envelope Exchange for the Generation of Live-Attenuated Arenavirus Vaccines
Andreas Bergthaler,Nicolas U Gerber,Doron Merkler,Edit Horvath,Juan Carlos de la Torre,Daniel D Pinschewer
PLOS Pathogens , 2006, DOI: 10.1371/journal.ppat.0020051
Abstract: Arenaviruses such as Lassa fever virus cause significant mortality in endemic areas and represent potential bioterrorist weapons. The occurrence of arenaviral hemorrhagic fevers is largely confined to Third World countries with a limited medical infrastructure, and therefore live-attenuated vaccines have long been sought as a method of choice for prevention. Yet their rational design and engineering have been thwarted by technical limitations. In addition, viral genes had not been identified that are needed to cause disease but can be deleted or substituted to generate live-attenuated vaccine strains. Lymphocytic choriomeningitis virus, the prototype arenavirus, induces cell-mediated immunity against Lassa fever virus, but its safety for humans is unclear and untested. Using this virus model, we have developed the necessary methodology to efficiently modify arenavirus genomes and have exploited these techniques to identify an arenaviral Achilles' heel suitable for targeting in vaccine design. Reverse genetic exchange of the viral glycoprotein for foreign glycoproteins created attenuated vaccine strains that remained viable although unable to cause disease in infected mice. This phenotype remained stable even after extensive propagation in immunodeficient hosts. Nevertheless, the engineered viruses induced T cell–mediated immunity protecting against overwhelming systemic infection and severe liver disease upon wild-type virus challenge. Protection was established within 3 to 7 d after immunization and lasted for approximately 300 d. The identification of an arenaviral Achilles' heel demonstrates that the reverse genetic engineering of live-attenuated arenavirus vaccines is feasible. Moreover, our findings offer lymphocytic choriomeningitis virus or other arenaviruses expressing foreign glycoproteins as promising live-attenuated arenavirus vaccine candidates.
Masas, pueblo y democracia: Un balance crítico de los debates sobre el nuevo populismo
De La Torre,Carlos;
Revista de ciencia política (Santiago) , 2003, DOI: 10.4067/S0718-090X2003000100005
Abstract: durante las últimas décadas se ha dado un verdadero renacer de los estudios sobre el populismo. los trabajos recientes se diferencian de los análisis del llamado populismo clásico porque en lugar de estudiarse al populismo como un régimen ligado a un tipo particular de políticas macroeconómicas, se lo analiza como un estilo o estrategia política (conniff 1999; knight 1998; weyland 1996, 2001; roberts 1995). el objetivo de este trabajo es discutir una serie de problemas no resueltos en los debates sobre el populismo clásico que han reaparecido en los trabajos sobre el neopopulismo. estos problemas son: 1) la relación entre el líder y sus seguidores, en especial la visión de éstos comomasas desorganizadas; 2) los diferentes usos de la categoría ?el pueblo?; y 3) las relaciones entre el populismo y la democracia liberal
Movimientos étnicos y cultura política en Ecuador
Torre , Carlos de la
Iconos : Revista de Ciencias Sociales , 2002,
Abstract:
Rese a de "Repensar América Latina" de Francisco Delich
Torre , Carlos de la
Iconos : Revista de Ciencias Sociales , 2005,
Abstract:
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