Diseño y fabricación de un pie ortopédico en materiales compuestos

67 p.En el presente documento de memoria se desarrolla el diseño estructural de una prótesis deportiva en materiales compuestos usando el método de Elementos Finitos. Posteriormente se realiza la fabricación de esta utilizando el Método de Infusión al Vacío. Este trabajo corresponde a una continuación del trabajo de memoria realizado por Sebastián Correa además de la interacción en conjunto del equipo de trabajo del laboratorio. Se realizó la implementación del laboratorio de Materiales Compuestos en la Universidad de Talca, el cual posee las herramientas y materiales requeridas para trabajar con estos materiales. Para la estimación de las condiciones del análisis como las cargas y la rigidez que debe poseer la prótesis, se realizó una investigación teórica de la biomecánica de la pierna humana para así conocer y estimar las fuerzas aplicadas a la prótesis para luego simularlo en el laboratorio de diseño y mecánica computacional. En el análisis estructural de la prótesis se utiliza fibra de vidrio unidireccional y fibra de carbono unidireccional, los cuales son materiales ortotrópicos con diferentes propiedades y la orientación de los apilamientos será a 0°. Este análisis se llevará a cabo mediante el software computacional ANSYS en donde se estimaron los desplazamientos de la estructura y posterior aplicación de los criterios de falla Tsai-Hill y Tsai-Wu. Se concluye con dos modelos de prótesis ortopédicas, uno utilizando resina epóxica reforzada con fibra de vidrio y la otra resina epóxica reforzada fibra de carbono, usando la misma geometría para ambas. Las comparaciones entre ambos modelos se explican, llegando a la conclusión de que el modelo con fibra de carbono es más liviano y con menos espesor, pero el modelo de fibra de vidrio, aunque es más pesado, soporta más cargas antes de la falla del material debido al espesor del modelo. La fabricación se realizó utilizando el método de Infusión al Vacío, el cual permitió la fabricación de la prótesis en el laboratorio de materiales compuestos de la Universidad de Talca. Se realizó una estimación los costos asociados a la fabricación de la prótesis considerando los materiales y mano de obra. PALABRAS CLAVE: Diseño, Prótesis, Materiales Compuestos, Elementos Finitos, Infusión al Vacío/ ABSTRACT: In the present document, the structural design of a sports prosthesis is developed in composite materials using the Finite Element method, and then, for the manufacturing , the Vacuum Infusion methods is performed. This work corresponds to a continuation of the memory work carried out by Sebastián Correa as well as the interaction of the laboratory work team. The implementation of the Laboratory of Composite Materials at the University of Talca was carried out, which now has the tools and materials required to work with these materials. The estimation of the conditions of the analysis such as the loads and the rigidity that he prosthesis must have, a theoretical investigation of the biomechanics of the human leg was made in order to know and estimate the forces applied to the prosthesis and then simulate this conditions in the design and computational mechanic laboratory. The structural analysis of the prosthesis uses unidirectional glass fiber and unidirectional carbon fiber, which are orthotropic materials with different properties and the orientation of the stacks used are at 0°. This analysis is developed using ANSYS computational software, where the displacements and stress of the structure and subsequent application of the Tsai-Hill and Tsai-Wu fault criteria were estimated. It concludes with two models of orthopedic prostheses, one using fiberglass and the other carbon fiber, using the same design for both. The comparisons between both models are explained, concluding that the carbon fiber model is lighter and with less thickness, but the fiberglass model, although heavier, supports more loads before the material failure due to the thickness of the model.,The manufacturing was carried out using the Vacuum Infusion method, which allowed the manufacture of the prosthesis in the laboratory of composite materials of the University of Talca. The costs associated with the manufacture of the prosthesis were estimated considering materials and labor. KEY WORDS: Design, Prosthesis, Composite Materials, Finite Element, Vacuum Infusion

Deletion of fabN in Enterococcus faecalis results in unsaturated fatty acid auxotrophy and decreased release of inflammatory cytokines

The Gram-positive bacterium Enterococcus faecalis can cause life-threatening infections and is resistant to several commonly used antibiotics. The type II fatty acid pathway in bacteria is discussed as a potential target for antimicrobial therapy. However, it was shown that inhibition or deletion of its enzymes can be rescued in Gram-positive bacteria by supplementation with fatty acids. Here we show that by deletion of the fabN gene, which is essential for unsaturated fatty acid (UFA) synthesis in E. faecalis, growth is impaired but can be rescued by supplementation with oleic acid or human serum. Nonetheless, we demonstrate alterations of the UFA profile after supplementation with oleic acid in the fabN mutant using a specific glycolipid. In addition, we demonstrate that cytokine release invitro is almost abolished after stimulation of mouse macrophages by the mutant in comparison to the wild type. The results indicate that fabN is not a suitable target for antimicrobials as UFA auxotrophy can be overcome. However, deletion of fabN resulted in a decreased inflammatory response indicating that fabN and resulting UFA synthesis are relevant for virulence

Enterococcal Membrane Vesicles as Vaccine Candidates

Enterococcus faecium is a leading cause of nosocomial infections, particularly in immunocompromised patients. The rise of multidrug-resistant E. faecium, including Vancomycin-Resistant Enterococci (VRE), is a major concern. Vaccines are promising alternatives to antibiotics, but there is currently no vaccine available against enterococci. In a previous study, we identified six protein vaccine candidates associated with extracellular membrane vesicles (MVs) produced by nosocomial E. faecium. In this study, we immunized rabbits with two different VRE-derived MV preparations and characterized the resulting immune sera. Both anti-MV sera exhibited high immunoreactivity towards the homologous strain, three additional VRE strains, and eight different unrelated E. faecium strains representing different sequence types (STs). Additionally, we demonstrated that the two anti-MV sera were able to mediate opsonophagocytic killing of not only the homologous strain but also three unrelated heterologous VRE strains. Altogether, our results indicate that E. faecium MVs, regardless of the purification method for obtaining them, are promising vaccine candidates against multidrug-resistant E. faecium and suggest that these naturally occurring MVs can be used as a multi-antigen platform to elicit protective immune responses against enterococcal infections

Conjugation of different immunogenic enterococcal vaccine target antigens leads to extended strain coverage

[Abstract] Enterococci have emerged as important nosocomial pathogens due to their resistance to the most commonly used antibiotics. Alternative treatments or prevention options are aimed at polysaccharides and surface-related proteins that play important roles in pathogenesis. Previously, we have shown that 2 Enterococcus faecium proteins, the secreted antigen A and the peptidyl-prolyl cis-trans isomerase, as well as the Enterococcus faecalis polysaccharide diheteroglycan, are able to induce opsonic and cross-protective antibodies. Here, we evaluate the use of glycoconjugates consisting of these proteins and an enterococcal polysaccharide to develop a vaccine with broader strain coverage. Diheteroglycan was conjugated to these 2 enterococcal proteins. Rabbit sera raised against these glycoconjugates showed Immunoglobulin G titers against the corresponding conjugate, as well as against the respective protein and carbohydrate antigens. Effective opsonophagocytic killing for the 2 sera was observed against different E. faecalis and E. faecium strains. Enzyme-linked immunosorbent assays against whole bacterial cells showed immune recognition of 22 enterococcal strains by the sera. Moreover, the sera conferred protection against E. faecalis and E. faecium strains in a mouse infection model. Our results suggest that these glycoconjugates are promising candidates for vaccine formulations with a broader coverage against these nosocomial pathogens and that the evaluated proteins are potential carrier proteins

Identification of Peptidoglycan-Associated Proteins as Vaccine Candidates for Enterococcal Infections

Infections by opportunistic bacteria have significant contributions to morbidity and mortality of hospitalized patients and also lead to high expenses in healthcare. In this setting, one of the major clinical problems is caused by Gram-positive bacteria such as enterococci and staphylococci. In this study we extract, purify, identify and characterize immunogenic surface-exposed proteins present in the vancomycin resistant enterococci (VRE) strain Enterococcus faecium E155 using three different extraction methods: trypsin shaving, biotinylation and elution at high pH. Proteomic profiling was carried out by gel-free and gel-nanoLC-MS/MS analyses. The total proteins found with each method were 390 by the trypsin shaving, 329 by the elution at high pH, and 45 using biotinylation. An exclusively extracytoplasmic localization was predicted in 39 (10%) by trypsin shaving, in 47 (15%) by elution at high pH, and 27 (63%) by biotinylation. Comparison between the three extraction methods by Venn diagram and subcellular localization predictors (CELLO v.2.5 and Gpos-mPLoc) allowed us to identify six proteins that are most likely surface-exposed: the SCP-like extracellular protein, a low affinity penicillin-binding protein 5 (PBP5),a basic membrane lipoprotein, a peptidoglycan-binding protein LysM (LysM),a D-alanyl-D-alanine carboxypeptidase (DdcP) and the peptidyl-prolyl cis-trans isomerase (PpiC). Due to their close relationship with the peptidoglycan, we chose PBP5, LysM, DdcP and PpiC to test their potential as vaccine candidates. These putative surface-exposed proteins were overexpressed in Escherichia coli and purified. Rabbit polyclonal antibodies raised against the purified proteins were able to induce specific opsonic antibodies that mediated killing of the homologous strain E. faecium E155 as well as clinical strains E. faecium E1162, Enterococcus faecalis 12030, type 2 and type 5. Passive immunization with rabbit antibodies raised against these proteins reduced significantly the colony counts of E. faecium E155 in mice, indicating the effectiveness of these surface-related proteins as promising vaccine candidates to target different enterococcal pathogens

Synthetic Teichoic Acid Conjugate Vaccine against Nosocomial Gram-Positive Bacteria

Lipoteichoic acids (LTA) are amphiphilic polymers that are important constituents of the cell wall of many Gram-positive bacteria. The chemical structures of LTA vary among organisms, albeit in the majority of Gram-positive bacteria the LTAs feature a common poly-1,3-(glycerolphosphate) backbone. Previously, the specificity of opsonic antibodies for this backbone present in some Gram-positive bacteria has been demonstrated, suggesting that this minimal structure may be sufficient for vaccine development. In the present work, we studied a well-defined synthetic LTA-fragment, which is able to inhibit opsonic killing of polyclonal rabbit sera raised against native LTA from Enterococcus faecalis 12030. This promising compound was conjugated with BSA and used to raise rabbit polyclonal antibodies. Subsequently, the opsonic activity of this serum was tested in an opsonophagocytic assay and specificity was confirmed by an opsonophagocytic inhibition assay. The conjugated LTA-fragment was able to induce specific opsonic antibodies that mediate killing of the clinical strains E. faecalis 12030, Enterococcus faecium E1162, and community-acquired Staphylococcus aureus strain MW2 (USA400). Prophylactic immunization with the teichoic acid conjugate and with the rabbit serum raised against this compound was evaluated in active and passive immunization studies in mice, and in an enterococcal endocarditis rat model. In all animal models, a statistically significant reduction of colony counts was observed indicating that the novel synthetic LTA-fragment conjugate is a promising vaccine candidate for active or passive immunotherapy against E. faecalis and other Gram-positive bacteria

Synthetic Teichoic Acid Conjugate Vaccine against Nosocomial Gram-Positive Bacteria

Lipoteichoic acids (LTA) are amphiphilic polymers that are important constituents of the cell wall of many Gram-positive bacteria. The chemical structures of LTA vary among organisms, albeit in the majority of Gram-positive bacteria the LTAs feature a common poly-1,3-(glycerolphosphate) backbone. Previously, the specificity of opsonic antibodies for this backbone present in some Gram-positive bacteria has been demonstrated, suggesting that this minimal structure may be sufficient for vaccine development. In the present work, we studied a well-defined synthetic LTA-fragment, which is able to inhibit opsonic killing of polyclonal rabbit sera raised against native LTA from Enterococcus faecalis 12030. This promising compound was conjugated with BSA and used to raise rabbit polyclonal antibodies. Subsequently, the opsonic activity of this serum was tested in an opsonophagocytic assay and specificity was confirmed by an opsonophagocytic inhibition assay. The conjugated LTA-fragment was able to induce specific opsonic antibodies that mediate killing of the clinical strains E. faecalis 12030, Enterococcus faecium E1162, and community-acquired Staphylococcus aureus strain MW2 (USA400). Prophylactic immunization with the teichoic acid conjugate and with the rabbit serum raised against this compound was evaluated in active and passive immunization studies in mice, and in an enterococcal endocarditis rat model. In all animal models, a statistically significant reduction of colony counts was observed indicating that the novel synthetic LTA-fragment conjugate is a promising vaccine candidate for active or passive immunotherapy against E. faecalis and other Gram-positive bacteria

Lipoproteína (a) y oligonucleótidos antisentido

Contexto: la Lipoproteína(a) (Lp(a)) fue descrita por primera vez por el genetista Kare Berg en 1963, aislada como un nuevo antígeno (en suero humano), asociada al colesterol de lipoproteínas de baja densidad. Posteriormente se reportó que sus niveles son determinados genéticamente y genera mayor riesgo de desarrollar aterosclerosis. En los últimos 20 años se ha incrementado la evidencia acerca de la estructura, genética y papel metabólico de la Lp(a), además de las posibles terapias para disminuir su aterogenicidad. Objetivo: aportar información sobre el papel de la Lp(a) en la enfermedad aterosclerótica y evaluar la nueva evidencia acerca de las terapias actuales, principalmente el papel de los oligonucleótidos antisentido. Metodología: revisión de la literatura en la base de datos PubMed, Google académico y literatura gris utilizando los términos MeSH: “lipoprotein(a)”, “atherosclerosis”, “physiopathology”, “therapeutics”, “drug therapy”, “oligonucleotides, antisense” y por revisión del listado de referencias bibliográficas (en “bola de nieve”) de los estudios seleccionados. Resultados: existe gran variedad de evidencia bibliográfica acerca de la Lp(a), su importancia en el desarrollo de enfermedad arteriosclerótica, y las múltiples opciones farmacológicas tanto aprobadas como en desarrollo usando esta molécula como diana terapéutica. Conclusiones: el entendimiento de la Lp(a) trae nuevas respuestas acerca de la enfermedad cardiovascular aterosclerótica; actualmente se encuentra en desarrollo farmacológico los oligonucleótidos antisentido, propuestos como una terapia prometedora para la modificación de sus niveles, sin embargo, es necesario esperar los desenlaces de la fase III de los ensayos para confirmar resultados preliminares

Implementación de Servicios Específicos con Zentyal

Este artículo expone el desarrollo de la actividad final del Diplomado de Profundización en Linux, la cual se realizó utilizando el sistema operativo Linux Zentyal Server, que es la base para disponer de los servicios de Infraestructura TI donde se realizaron configuraciones de DHCP, DNS, Proxy, Firewall, File Server, Print Server y VPN. Las configuraciones se aprobaron a través de Ubuntu Desktop, y se demuestra la funcionalidad de las configuraciones realizadas en cada paso.This article show us the development of the final activity deepening diploma in Linux which was carried out using the operating system, Linux Zentyal Server, which is the basis for having the IT infrastructure services where configurations were made, DHCP, DNS, PROXY, Firewall, File Server, Print Server and VPN, the configurations were tested through Ubuntu Desktop and the functionality of the configurations made in each step is demonstrated

Desafíos actuales de la educación superior

El presente libro corresponde al trabajo investigativo realizado por sus autores frente a los desafíos que enfrenta y enfrentará la educación en tiempos actuales (provisional)