49 research outputs found

    Diseño de bloques de concreto tipo lego con adición de fibras de acero, para mejorar la resistencia a la compresión, Tarapoto – 2021

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    La investigación denominada “Diseño de bloques de concreto tipo lego con adición de fibras de acero, para mejorar la resistencia a la compresión, Tarapoto – 2021”. presenta frutos conseguidos en el desarrollo de la tesis, para fabricar un nuevo bloque de concreto qué encaja uno con otros, con el propósito de reducir costos en la implementación del concreto y también haciendo uso de fibra de acero para mejorar las propiedades mecánicas de dicho bloque. Donde se realizó ensayos a los agregados: granulometría, contenido de humedad, peso específico, absorción peso unitario, peso suelto y compactado, para determinar sus propiedades. mientras que la fibra de acero, se extrajo manualmente por los tesistas, con porcentajes del 1% al 3% y el 5%, con variables, debido a que fueron fibras de acero recicladas, seleccionadas y clasificadas con medidas inferiores a 3 cm. como resultado se obtuvo 36 especímenes, para ensayos de resistencia a la comprensión, absorción, alabeo y deformación. Finalmente se concluyó que al agregar 1%, 3% y 5% de fibras de acero al bloque de concreto los valores de resistencia a la compresión a los 28 días de fraguado fueron 104.73% 119, 43% y 57%, la resistencia aumenta a 9%

    Chagas' disease: an update on immune mechanisms and therapeutic strategies

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    The final decade of the 20th century was marked by an alarming resurgence in infectious diseases caused by tropical parasites belonging to the kinetoplastid protozoan order. Among the pathogenic trypanosomatids, some species are of particular interest due to their medical importance. These species include the agent responsible for Chagas' disease, Trypanosoma cruzi. Approximately 8 to 10 million people are infected in the Americas, and approximately 40 million are at risk. in the present review, we discuss in detail the immune mechanisms elicited during infection by T. cruzi and the effects of chemotherapy in controlling parasite proliferation and on the host immune system.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Instituto Nacional de Biologia Estrutural e QuImica Medicinal em Doencas Infecciosas (INBEQMeDI)Univ São Paulo, Inst Biomed Sci, Dept Parasitol, São Paulo, BrazilMackenzie Presbeterian Univ, Ctr Biomol Sci & Hlth, São Paulo, BrazilNatl Univ Rosario, Sch Med Sci, Inst Immunol, Rosario, Santa Fe, ArgentinaCSIC, Inst Parasitol & Biomed Lopez Neyra, Granada, SpainUniversidade Federal de São Paulo, Dept Microbiol Immunol & Parasitol, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Microbiol Immunol & Parasitol, São Paulo, BrazilFAPESP: 08/57596-4FAPESP: 07/08648-9CNPq: 473906/2008-2Web of Scienc

    A Novel Method for Inducing Amastigote-To-Trypomastigote Transformation In Vitro in Trypanosoma cruzi Reveals the Importance of Inositol 1,4,5-Trisphosphate Receptor

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    Background Trypanosoma cruzi is a parasitic protist that causes Chagas disease, which is prevalent in Latin America. Because of the unavailability of an effective drug or vaccine, and because about 8 million people are infected with the parasite worldwide, the development of novel drugs demands urgent attention. T. cruzi infects a wide variety of mammalian nucleated cells, with a preference for myocardial cells. Non-dividing trypomastigotes in the bloodstream infect host cells where they are transformed into replication-capable amastigotes. The amastigotes revert to trypomastigotes (trypomastigogenesis) before being shed out of the host cells. Although trypomastigote transformation is an essential process for the parasite, the molecular mechanisms underlying this process have not yet been clarified, mainly because of the lack of an assay system to induce trypomastigogenesis in vitro. Methodology/Principal Findings Cultivation of amastigotes in a transformation medium composed of 80% RPMI-1640 and 20% Grace\u27s Insect Medium mediated their transformation into trypomastigotes. Grace\u27s Insect Medium alone also induced trypomastigogenesis. Furthermore, trypomastigogenesis was induced more efficiently in the presence of fetal bovine serum. Trypomastigotes derived from in vitro trypomastigogenesis were able to infect mammalian host cells as efficiently as tissue-culture-derived trypomastigotes (TCT) and expressed a marker protein for TCT. Using this assay system, we demonstrated that T. cruzi inositol 1,4,5-trisphosphate receptor (TcIP3R) - an intracellular Ca2+ channel and a key molecule involved in Ca2+ signaling in the parasite - is important for the transformation process. Conclusion/Significance Our findings provide a new tool to identify the molecular mechanisms of the amastigote-totrypomastigote transformation, leading to a new strategy for drug development against Chagas disease

    Effects of hospital facilities on patient outcomes after cancer surgery: an international, prospective, observational study

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    Background Early death after cancer surgery is higher in low-income and middle-income countries (LMICs) compared with in high-income countries, yet the impact of facility characteristics on early postoperative outcomes is unknown. The aim of this study was to examine the association between hospital infrastructure, resource availability, and processes on early outcomes after cancer surgery worldwide.Methods A multimethods analysis was performed as part of the GlobalSurg 3 study-a multicentre, international, prospective cohort study of patients who had surgery for breast, colorectal, or gastric cancer. The primary outcomes were 30-day mortality and 30-day major complication rates. Potentially beneficial hospital facilities were identified by variable selection to select those associated with 30-day mortality. Adjusted outcomes were determined using generalised estimating equations to account for patient characteristics and country-income group, with population stratification by hospital.Findings Between April 1, 2018, and April 23, 2019, facility-level data were collected for 9685 patients across 238 hospitals in 66 countries (91 hospitals in 20 high-income countries; 57 hospitals in 19 upper-middle-income countries; and 90 hospitals in 27 low-income to lower-middle-income countries). The availability of five hospital facilities was inversely associated with mortality: ultrasound, CT scanner, critical care unit, opioid analgesia, and oncologist. After adjustment for case-mix and country income group, hospitals with three or fewer of these facilities (62 hospitals, 1294 patients) had higher mortality compared with those with four or five (adjusted odds ratio [OR] 3.85 [95% CI 2.58-5.75]; p<0.0001), with excess mortality predominantly explained by a limited capacity to rescue following the development of major complications (63.0% vs 82.7%; OR 0.35 [0.23-0.53]; p<0.0001). Across LMICs, improvements in hospital facilities would prevent one to three deaths for every 100 patients undergoing surgery for cancer.Interpretation Hospitals with higher levels of infrastructure and resources have better outcomes after cancer surgery, independent of country income. Without urgent strengthening of hospital infrastructure and resources, the reductions in cancer-associated mortality associated with improved access will not be realised

    La responsabilidad estatal y sus acciones frente a la recuperacion del espacio pĂşblico

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    Durante las dos ultimas decanas la creciente Colombia a generado diferentes doctrinas y pensamientos en torno a un problema que lejos de soluciónarse se agudiza con los continuos aumentos en los índices de desplazados y desempleados en el país, esta regla que extrañamente resulta ser directamente proporcional en cuando si aumentanestos aumenta también el índice de vendedores ambulantes, vulnerando en torno a esta problem tica una cierta cantidad de derechos. Es por esto que nuestro estudio esta focalizado a encontrar no solamente los aspectos generadores de esta problem tica sino también como el estado Colombiana lo confronta atreves de planes o programas gubernamentales en pro de la conservación del espacio público en ciertas ciudades o espacios que sufren de este debate entre el derecho al trabajo y el derecho al espacio público. Con la creación de la constitución de 1991, se ha generado para el estado Colombiano un peso que se ha mantenido durante mucho tiempo. Es así que creación de esta constitución se establecieron derechos como al espacio público y al trabajo, derechos que han entrado en conflicto y se han mantenido así desde la poca haesta nuestros días siendo alimentados día a día tras otras dos problem ticas en Colombia como lo son el desempleo y el conflicto armado interno y por ende los desplazados

    The Trypanosoma cruzi metacyclic-specific protein Met-III associates with the nucleolus and contains independent amino and carboxyl terminal targeting elements.

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    Metacyclogenesis in Trypanosoma cruzi involves the differentiation of replicating non-infective epimastigotes into non-replicating metacyclic trypomastigotes. This pre-adapts parasites for infection of the mammalian host and is characterised by several morphological changes and structural alterations to the nucleus, including nucleolar disaggregation. Experimental investigation of these developmental processes has been hampered by a lack of robust molecular markers. Here, we describe the precise temporal expression of the T. cruzi-specific protein Met-III, in the genome reference strain CL Brener. Expression is restricted to metacyclics in the insect stages of the life-cycle and is rapidly down-regulated following invasion of mammalian cells. Met-III localises to dispersed foci typical of the disassembled nucleolus in metacyclics and to the discrete single nucleolus of cells soon after macrophage invasion. To identify elements that target Met-III, we generated a series of tagged green fluorescent protein fusion proteins and examined their sub-nuclear location in transformed parasites. These experiments demonstrated that amino and carboxyl terminal fragments, characterised by clusters of basic residues, could independently mediate nucleolar sequestration. To investigate the function of Met-III, we used gene deletion. This showed that Met-III is not required for the development of metacyclic trypomastigotes and that null mutants can complete the life-cycle in vitro
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