936 research outputs found

    Mapping the Innovation Ecosystems for the Deployment of Small Modular Reactors in Canada and Mexico: An Innovation Policy Approach Through Strategic Niche Management and Social Network Analysis.

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    Small Modular Reactors (SMRs) have received considerable attention as their specific designs reduce implementation times and costs, allowing modularity to increase the installed capacity for energy generation. Although SMRs represent a reliable, affordable, and sustainable alternative to meet our growing energy demands, this technology faces deployment obstacles that may require outside interventions to speed up their adoption so that people can enjoy their societal, environmental and economic benefits. Just as a country´s best energy mix approach varies by resource availability and institutional capabilities, the actors promoting SMR adoption constitute an innovation ecosystem uniquely responsive to country-specific characteristics. This thesis uses a Strategic Niche Management (SNM) framework that proposes interventions in protected spaces to determine the optimal conditions for successful deployment and appropriate policy while consolidating a community of early adopters. Through Social Network Analysis (SNA), this thesis compares how these SMR innovation ecosystems are formed in Canada and Mexico, highlighting structural differences between developed and developing countries. This primary framework and research method are then complemented with the Helix Model IV for a comprehensive review of the governance of SMR innovation ecosystems. Policy and network structures are assumed to have a feedback loop effect on each other and SMR deployment potential. Secondary data were collected from publicly available information and processed under the software Gephi 9.5. Contrary to most research, which focuses solely on centralized actors in a network, this thesis explores the contributions of both centralized and peripheral actors to the network, so policymakers can discern where to efficiently allocate resources depending on their intervention objectives and their main focus. Results indicate that the Mexican SMR ecosystem, with its visually different network structure in all the snapshots, is more vulnerable than the Canadian ecosystem. This difference is especially apparent in the scene where five of the most centralized actors are removed from the two SMR ecosystems

    Plan para incrementar la población estudiantil y capacidad instalada de la Universidad de El Salvador

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    El trabajo de la Universidad, es el de prestar un servicio social, persiguiendo la elevación espiritual del hombre salvadoreño, la difusión de la enseñanza superior, la investigación científica como la señala la - ley orgánica de la Universidad de El Salvador; en su Ley Constitutiva la Asamblea Legislativa, recoge estos principios y señala en su considerando II: "Que la Universidad está obligada a prestar un servicio social, persiguiendo la elevación espiritual del hombre salvadoreño, difusión de la enseñanza superior y la investigación científica; y que por complejidad, especialidad e importancia de tales objetivos el constituyente dota a la Universidad de autonomía en lo administrativo, lo docente y lo económico a fin de que dentro del orden jurídico naciona

    Immune protection against Trypanosoma cruzi induced by TcVac4 in a canine model

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    Chagas disease, caused by Trypanosoma cruzi, is endemic in southern parts of the American continent. Herein, we have tested the protective efficacy of a DNA-prime/T. rangeli-boost (TcVac4) vaccine in a dog (Canis familiaris) model. Dogs were immunized with two-doses of DNA vaccine (pcDNA3.1 encoding TcG1, TcG2, and TcG4 antigens plus IL-12- and GMCSF- encoding plasmids) followed by two doses of glutaraldehyde-inactivated T. rangeli epimastigotes (TrIE); and challenged with highly pathogenic T. cruzi (SylvioX10/4) isolate. Dogs given TrIE or empty pcDNA3.1 were used as controls. We monitored post-vaccination and post-challenge infection antibody response by an ELISA, parasitemia by blood analysis and xenodiagnosis, and heart function by electrocardiography. Post-mortem anatomic and pathologic evaluation of the heart was conducted. TcVac4 induced a strong IgG response (IgG2>IgG1) that was significantly expanded post-infection, and moved to a nearly balanced IgG2/IgG1 response in chronic phase. In comparison, dogs given TrIE or empty plasmid DNA only developed high IgG titers with IgG2 predominance in response to T. cruzi infection. Blood parasitemia, tissue parasite foci, parasite transmission to triatomines, electrocardiographic abnormalities were significantly lower in TcVac4-vaccinated dogs than was observed in dogs given TrIE or empty plasmid DNA only. Macroscopic and microscopic alterations, the hallmarks of chronic Chagas disease, were significantly decreased in the myocardium of TcVac4-vaccinated dogs.We conclude that TcVac4 induced immunity was beneficial in providing resistance to T. cruzi infection, evidenced by control of chronic pathology of the heart and preservation of cardiac function in dogs. Additionally, TcVac4 vaccination decreased the transmission of parasites from vaccinated/infected animals to triatomines.CONACYT PROY No. 156701 UAEM PROY No. 2381/2006U National Institutes of Health/National Institute of Allergy and Infectious Diseases http://www.niaid.nih.gov/Pages/ default.aspx GRANT NUMBER (AI072538) NJG; American Heart Association http://www.heart.org/ HEARTORG/ GRANT NUMBER (0855059F) to NJG

    Effects of astaxanthin in mice acutely infected with Trypanosoma cruzi

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    During Trypanosoma cruzi infection, oxidative stress is considered a contributing factor for dilated cardiomyopathy development. In this study, the effects of astaxanthin (ASTX) were evaluated as an alternative drug treatment for Chagas disease in a mouse model during the acute infection phase, given its anti-inflammatory, immunomodulating, and anti-oxidative properties. ASTX was tested in vitro in parasites grown axenically and in co-culture with Vero cells. In vivo tests were performed in BALB/c mice (4–6 weeks old) infected with Trypanosoma cruzi and supplemented with ASTX (10 mg/kg/day) and/or nifurtimox (NFMX; 100 mg/kg/day). Results show that ASTX has some detrimental effects on axenically cultured parasites, but not when cultured with mammalian cell monolayers. In vivo, ASTX did not have any therapeutic value against acute Trypanosoma cruzi infection, used either alone or in combination with NFMX. Infected animals treated with NFMX or ASTX/NFMX survived the experimental period (60 days), while infected animals treated only with ASTX died before day 30 post-infection. ASTX did not show any effect on the control of parasitemia; however, it was associated with an increment in focal heart lymphoplasmacytic infiltration, a reduced number of amastigote nests in cardiac tissue, and less hyperplasic spleen follicles when compared to control groups. Unexpectedly, ASTX showed a negative effect in infected animals co-treated with NFMX. An increment in parasitemia duration was observed, possibly due to ASTX blocking of free radicals, an antiparasitic mechanism of NFMX. In conclusion, astaxanthin is not recommended during the acute phase of Chagas disease, either alone or in combination with nifurtimox.CONACYT PROY NO. 000000000156701. (REGISTRO INTERNO UAEM 3326

    Molecular and Biological Characterization of the Murine Leukotriene B4 Receptor Expressed on Eosinophils

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    The movement of leukocytes into tissues is regulated by the local production of chemical mediators collectively referred to as chemoattractants. Although chemoattractants constitute a diverse array of molecules, including proteins, peptides, and lipids, they all appear to signal leukocytes through a related family of seven transmembrane–spanning G protein–coupled receptors. The eosinophil is a potent proinflammatory cell that is attracted into tissues during allergic inflammation, parasitic infection, and certain malignancies. Since the molecular mechanisms controlling eosinophil recruitment are incompletely understood, we performed a degenerate polymerase chain reaction on cDNA isolated from murine eosinophils to identify novel chemoattractant receptors. We report the isolation of a cDNA that encodes a 351–amino acid glycoprotein that is 78% identical to a human gene that has been reported to be a purinoceptor (P2Y7) and a leukotriene B4 (LTB4) receptor (BLTR). Chinese hamster ovary (CHO) cells transfected with this cDNA specifically bound [3H]LTB4 with a dissociation constant of 0.6 ± 0.1 nM. Furthermore, LTB4 induced a dose-dependent intracellular calcium flux in transfected CHO cells. In contrast, [35S]dATP did not specifically bind to these transfectants. This mRNA was expressed at high levels in interleukin 5–exposed eosinophils, elicited peritoneal macrophages and neutrophils, and to a lesser extent interferon γ stimulated macrophages. Low levels of expression were detected in the lung, lymph node, and spleen of unchallenged mice. Western blot analysis detected the mBLTR protein in murine eosinophils and alveolar macrophages as well as human eosinophils. In addition, elevated levels of mBLTR mRNA were found in the lungs of mice in a murine model of allergic pulmonary inflammation in a time course consistent with the influx of eosinophils. Our findings indicate that this murine receptor is an LTB4 receptor that is highly expressed on activated leukocytes, including eosinophils, and may play an important role in mediating eosinophil recruitment into inflammatory foci

    TcVac1 vaccine delivery by intradermal electroporation enhances vaccine induced immune protection against Trypanosoma cruzi infection in mice

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    Trabajo de investigación doctoral de Wael Hegazy Hassan Moustafa bajo la dirección de Juan Carlos Vázquez ChagoyánThe efforts for the development and testing of vaccines against Trypanosoma cruzi infection have increased during the past years. We have designed a TcVac series of vaccines composed of T. cruzi derived, GPI-anchored membrane antigens. The TcVac vaccines have been shown to elicit humoral and cellular mediated immune responses and provide significant (but not complete) control of experimental infection in mice and dogs. Herein, we aimed to test two immunization protocols for the delivery of DNA-prime/ DNA-boost vaccine (TcVac1) composed of TcG2 and TcG4 antigens in a BALB/c mouse model. Mice were immunized with TcVac1 through intradermal/electroporation (IDE) or intramuscular (IM) routes, challenged with T. cruzi, and evaluated during acute phase of infection. The humoral immune response was evaluated through the assessment of anti-TcG2 and anti-TcG4 IgG subtypes by using an ELISA. Cellular immune response was assessed through a lymphocyte proliferation assay. Finally, clinical and morphopathological aspects were evaluated for all experimental animals. Our results demonstrated that when comparing TcVac1 IDE delivery vs IM delivery, the former induced significantly higher level of antigen-specific antibody response (IgG2a + IgG2b > IgG1) and lymphocyte proliferation, which expanded in response to challenge infection. Histological evaluation after challenge infection showed infiltration of inflammatory cells (macrophages and lymphocytes) in the heart and skeletal tissue of all infected mice. However, the largest increase in inflammatory infiltrate was observed in TcVac1_IDE/Tc mice when compared with TcVac1_IM/Tc or non-vaccinated/infected mice. The extent of tissue inflammatory infiltrate was directly associated with the control of tissue amastigote nests in vaccinated/ infected (vs. non-vaccinated/infected) mice. Our results suggest that IDE delivery improves the protective efficacy of TcVac1 vaccine against T. cruzi infection in mice when compared with IM delivery of the vaccine.Universidad Autónoma de Estado de México (proyecto No. 3326/2012C), Consejo Nacional de Ciencia y Tecnología (Proyecto No. 156701) . Beca CONACyT a M.Sc. Wael Hegazy Hassan Moustafa (Beca numero No. 518232/291117)
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