1,720,967 research outputs found
Desarrollo de una herramienta analíítica basada en Espectrometría de Masas aplicable a la producción de antígenos recombinantes de STEC.
Full text linkTesis de MaestríaLas cepas de Escherichia coli productoras de toxina Shiga (STEC) son patógenos altamente zoonóticos transmitidos por alimentos. Representan un grave problema de salud pública, siendo las principales responsables del síndrome urémico hemolítico (SHU), enfermedad endémica en Argentina. Las bases moleculares del mecanismo de infección son complejas e involucran diversos factores de virulencia. Las proteínas codificadas por el locus de borramiento de enterocitos (LEE) se han probado como componentes de formulaciones vacunales contra la portación de STEC en bovinos. Este locus incluye EspA y EspB, y el receptor de translocación para intimina (Tir), que se secretan a través de un sistema de secreción tipo III (TTSS), y la adhesina intimina. En esta tesis, se desarrolló una herramienta para el análisis de la expresión de proteínas recombinantes, aplicable a otras de interés. Esta herramienta es útil para evaluar la composición antropogénica de las formulaciones vacunales y para el control de calidad de sus procesos de producción, entre otros. Se trabajó con tres factores de virulencia recombinantes: EspA, Inmin y la subunidad B de la toxina Shiga 2 (Stx2B). Esta proteína desempeña un papel fundamental en la colonización del ganado y es responsable de la patogenicidad en humanos. En la primera parte de este trabajo, se optimizaron las condiciones de expresión y purificación de las proteínas recombinantes, y se generaron sueros policlonales para su reconocimiento específico. Con base en las limitaciones observadas, en la segunda parte, se abordó una estrategia diferente mediante el desarrollo de una herramienta analítica basada en cromatografía líquida (LC) acoplada a espectrometría de masas (MS). Se optimizaron las condiciones de separación por LC y, dentro de las técnicas basadas en MS, se trabajó en la cuantificación de proteínas en su estructura completa mediante monitoreo de reacciones múltiples (MRM). Se realizó una optimización automatizada de todas las variables analizadas mediante el software Labsolutions, proporcionado por el equipo Shimadzu LC-MS 8030. A partir de estas condiciones optimizadas, se elaboró una curva de calibración en muestras que contenían cantidades conocidas de proteínas de interés, contrastando la intensidad de la señal en los MRM con la concentración de proteínas en la muestra. Este trabajo proporciona una metodología de detección/cuantificación aplicable a muestras más complejas y como herramienta de control en un laboratorio de referencia nacional como el de I+D+i del Instituto Nacional de Producción Biológica del ANLIS “Dr. Carlos G. Malbrán”.Shiga Toxin producing Escherichia coli (STEC) strains are highly zoonotic foodborne pathogens. These represent a serious problem for public health, being the main responsible for the disease known as Hemolytic Uremic Syndrome (HUS), endemic in Argentina. The molecular bases of the infection mechanism are complex, involving several virulence factors. The proteins encoded by the Locus of Enterocytes Effacement (LEE) have been tested as components of vaccine formulations against carriage of STEC in cattle. This locus includes EspA and EspB, and the translocation receptor for Intimin (Tir), which are secreted through a type III secretion system (TTSS), and the adhesin Intimin. In this thesis work, a tool was developed for the analysis of the expression of recombinant proteins, applicable to others of interest. This tool is useful for evaluating the antigenic composition of vaccine formulations and for quality control of their production processes, among others. We worked with three recombinant virulence factors: EspA, Intimin and the B subunit of the Shiga Toxin 2 (Stx2B). This protein plays a main role in the colonization of catle and is responsible for pathogenicity in humans. In the first part of this work, the expression and purification conditions of the recombinant proteins were optimized, and polyclonal sera were generated aimed at their specific recognition. Based on the limitations observed, in the second part, a different strategy was addressed by developing an analytical tool based on liquid chromatography (LC) coupled to Mass Spectrometry (MS). LC separation conditions were optimized and, within MS-based techniques, we worked on the quantification of proteins in their complete structure using multiple reaction monitoring (MRM). An automated optimization of all the variables tested was carried out through the Labsolutions software provided by the Shimadzu LC-MS 8030 equipment. From these optimized conditions, a calibration curve was carried out on samples containing known quantities of proteins of interest, contrasting the signal intensity in the MRMs with the protein concentration in the sample. This work provides a detection/quantification methodology that is applicable for more complex samples and as a control tool in a national reference laboratory such as the R&D&i within the National Institute of Biological Production of the ANLIS “Dr. Carlos G. Malbrán”.Fil: Ávila, Lucía. Universidad Nacional de San Martín. Escuela de Bio y Nanotecnologías; Buenos Aires, Argentina
Caracterización molecular y funcional de la respuesta de la acidez en Bordetella bronchiseptica : Posible rol en la infección persistente
No full textEl presente trabajo de tesis se ha focalizado en el estudio del comportamiento de Bordetella bronchiseptica frente a una condición de estrés ambiental como lo es la acidez. La elección de esta temática responde a que este patógeno respiratorio, capaz de inducir un conjunto de enfermedades denominadas bordetellosis, enfrenta y sobrelleva esta condición de estrés durante su ciclo de vida. La capacidad de resistir a a condiciones de acidez podría permitir a B. bronchiseptica inducir estadíos crónicos de la enfermedad, los cuales garantizan no sólo la sobrevida del patógeno dentro del huésped sino posibilitan la continuación de la circulación del mismo dentro de una población. Este estadío de cronicidad constituye por ello un problema para la salud. La profundización de este conocimiento relacionado a la sobrevida de B. bronchiseptica en condiciones de estrés, contriburía a un mejor manejo sanitario de este patógeno, capaz de inducir enfermedades en un amplio rango de huéspedes que incluye al hombre.
En este contexto, en mi trabajo de tesis doctoral he abordado los siguientes objetivos específicos:
• Evaluación del crecimiento de B. bronchiseptica en diferentes condiciones de acidez. Determinación de los valores de pH límite para el crecimiento
• Evaluación de la capacidad B. bronchiseptica de desarrollar una respuesta de tolerancia a la acidez (ATR).
• Impacto de los fenotipos virulento y avirulento de B. bronchiseptica en el proceso de resistencia/adaptación a la condición de estrés estudiada.
• Identificación de componentes proteicos asociados al proceso de resistencia/adaptación mediante espectrometría de masas del tipo UV-MALDI TOF y TOF/TOF. Análisis proteómico de expresión diferencial 2D-PAGE.
• Análisis y discusión del posible rol de los marcadores de respuesta a la acidificación del medio encontrados sobre el ciclo biológico del patógeno.Doctor en Ciencias Exactas, área Ciencias BiológicasUniversidad Nacional de La PlataFacultad de Ciencias Exacta
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
- …
