Detección de cepas de Escherichia coli Shiga Toxigénica (STEC) y enteropatógena (EPEC) basada en PCR multiplex

Escherichia coli (STEC) y (EPEC) causan enfermedades gastrointestinales y pertenecen a los serogrupos 0111, 0157 y otros, frente a lo cual se planteó como objetivo implementar la técnica de PCR múltiplex para diagnosticar y caracterizar sus genes de virulencia. Se desarrollaron tres PCR multiplex: en la primera fueron empleados tres pares de iniciadores específicos de  la  región   rfbE (codificante  del  antígeno  O) del serotipo 0157:H7, del gen eaeA que  codifica  la proteína intimina y del gen hIyA codificante de  hemolisina, los cuales generaron productos de 259, 384 y 534 pb. En la segunda PCR se detectaron los genes de la sub-unidad A de las shigatoxinas stx1, stx2, incluidas las variantes de stx2. con amplicones de 180 y 255 pb. En la tercera se utilizaron iniciadores para stx1, stx2, eaeA y hIyA. Se determinó la selectividad de los iniciadores con cepas STEC, ATCC y se detectó hasta 1 UFC, lo cual demuestra su alta sensibilidad.  Palabras clave: Serogrupos, virulencia, iniciadores, intimina, hemolisina

El trabajo experimental en la enseñanza de las reacciones de ácidos y bases

Este trabajo busca fundamentar y determinar la influencia del trabajo experimental en la enseñanza y la aprehensión de las reacciones de ácidos y bases, a partir del paradigma constructivista con énfasis en una didáctica experimental para la enseñanza de estos conceptos, beneficiando el aprendizaje real. Se muestra la experimentación como instrumento mediador de integración de la teoría, que en ocasiones se vuelve dificultosa para los estudiantes, con la práctica y su aplicabilidad, lo que proporciona un formidable recurso para la enseñanza- aprendizaje. La muestra de estudio constó de los estudiantes de los Segundos de Bachillerato, de la sección matutina de la Unidad Educativa Fiscal “Portoviejo”, escogidos cuarenta estudiantes entre los siete paralelos, de forma aleatoria, y se ejecutaron cuatro momentos en la metodología, Fase de Indagación de conocimientos de los conceptos científicos ácido base y Ph, fase de introducción y estructuración de nuevos modelos experimentales explicativos, fase de síntesis y aplicación de nuevos modelos y la del diseño de clases utilizando la experimentación en el proceso de enseñanza-aprendizaje, para luego evaluar el aprendizaje de los estudiantes, acercando la Química a los educandos, mediante experiencias, al cuestionar y formular preguntas sobre lo que sucede en su entorno, y determinándose al final que la interacción de la teoría y la práctica, de la temática tratada, conlleva el desarrollo de actitudes para la formación integral y significativa del individuo. PALABRAS CLAVE: experimentación; constructivista; ácido; base; teoría. Experimental work in teaching the reactions of acids and bases. ABSTRACT This work seeks to base and determine the influence of experimental work on the teaching and apprehension of acid and base reactions, based on the constructivist paradigm with emphasis on an experimental didactic for teaching these concepts, benefiting real learning. Experimentation is shown as a mediating instrument for the integration of theory, which sometimes becomes difficult for students, with practice and its applicability, which provides a formidable resource for teaching-learning. The study sample consisted of the students of the Secondary School Seconds, of the morning section of the Fiscal Education Unit "Portoviejo", chosen forty students among the seven parallels, randomly, and four moments in the methodology were executed, Phase of Investigation of knowledge of the scientific concepts acid base and Ph, phase of introduction and structuring of new explanatory experimental models, phase of synthesis and application of new models and the design of classes using experimentation in the teaching-learning process, and then evaluate student learning, bringing chemistry to students, through experiences, by questioning and asking questions about what is happening in their environment, and determining in the end that the interaction of theory and practice, of the subject matter, entails the development of attitudes for the integral and meaningful formation of the individual. KEYWORDS: experimentation; constructivist; acid; base; theory

Fluorescent Nanoparticles from Several Commercial Beverages: Their Properties and Potential Application for Bioimaging

The presence of nanoparticles in beverages has raised great concern in terms of potential impacts to consumer health. Herein, carbon dots in beverages kvass, pony malta, pilsner beer, Vivant Storm, and Profit were identified. They were shown to have a strong fluorescence under the excitation of ultraviolet light. The emission peaks shift to longer wavelengths accompanied by a remarkable fluorescence intensity decrease. The carbon dots are in the nanosized range and roughly spherical in appearance. Elemental analysis by X-ray photoelectron spectroscopy demonstrated the composition of Kvass carbon dots to be C 83.17%, O 13.83%, and N 3.00%. No cytotoxicity was found at concentrations up to 20 mg/mL for human tongue squamous carcinoma cells, and they can be directly applied in both carcinoma and onion epidermal cell imaging. This work represents the first report of the carbon dots present in beverages, providing valuable insights into these nanoparticles for future biological imaging

El trabajo cooperativo y el interaprendizaje en los estudiantes de Química de primero de bachillerato

La presente investigación se la realizó debido a la importancia que implica la calidad de educación que se imparta a los estudiantes en el aula de clases y se cumplan los objetivos que en un principio fueron establecidos por los docentes. Hay que estar conscientes de que, el proceso educativo es una cadena de propuestas objetivas que deben cumplir en un orden secuencial hasta cumplir su objetivo final que es la formación académica de un ser humano listo para enfrentar, cumplir nuevos retos y metas. El aprendizaje cooperativo constituye una de las metodologías alternativas de gran importancia en el proceso de interaprendizaje que permite desarrollar habilidades y destrezas grupales que promuevan la motivación del estudiante. En este sentido se pudo determinar la incidencia del trabajo cooperativo en el interaprendizaje de los estudiantes en la asignatura de Química en la Unidad Educativa fiscal “José Leónidas Delgado” mediante la aplicación de los métodos descriptivos y propositivos, fortaleciendo el aprendizaje de manera colectiva, generando mayor motivación y el deseo de aprender de manera cooperativa. PALABRAS CLAVE: Metodología; colaboración; motivación; innovación. Cooperative work and inter-learning in Chemistry students of the first year of high school ABSTRACT This research was carried out due to the importance of the quality of education given to students in the classroom and the objectives that were initially established by teachers are met. We must be aware that the educational process is a chain of objective proposals that must be met in a sequential order until they reach their final objective, which is the academic formation of a human being ready to face, meet new challenges and goals. Cooperative learning is one of the alternative methodologies of great importance in the inter-learning process that allows developing group skills and abilities that promote student motivation. In this sense, it was possible to determine the incidence of cooperative work in the inter-learning of students in the subject of chemistry in the Fiscal Education Unit "José Leónidas Delgado", through the application of descriptive and propositive methods, strengthening learning collectively, generating greater motivation and the desire to learn cooperatively. KEYWORDS: Methodology; collaboration; motivation; innovation

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

Detección de cepas de Escherichia coli Shiga Toxigénica (STEC) y enteropatógena (EPEC) basada en PCR multiplex

Escherichia coli (STEC) and (EPEC) cause gastrointestinal diseases. These bacteria belong to the serogroup 0111, 0157 and others. The stated objective is to implement the PCR multiplex technique to diagnose and characterize its virulence genes. Three PCR multiplex were developed; in the first one, three pairs of specific initiators were used from region rfbE (encoding of antigen 0) of serotype 0157:H7, of gen eaeA that encodes the intimin protein and gen hlyA encoding of hemolysin, which generates products of 259, 384 y 534 pb. In the second PCR the genes of subunit A of shigatoxins stx1 , stx2 (including variants of stx2 ) were detected, with amplicons of 180 and 255 bp. In the third PCR, initiators to stx1, stx2, eaeA and hlyA were used. The selectivity of initiators with strains STEC, ATCC was determined and it was detected up to 1 UFC, which demonstrates its high sensitivityEscherichia coli (STEC) y (EPEC) causan enfermedades gastrointestinales y pertenecen a los serogrupos 0111, 0157 y otros, frente a lo cual se planteó como objetivo implementar la técnica de PCR múltiplex para diagnosticar y caracterizar sus genes de virulencia. Se desarrollaron tres PCR multiplex: en la primera fueron empleados tres pares de iniciadores específicos de  la  región   rfbE (codificante  del  antígeno  O) del serotipo 0157:H7, del gen eaeA que  codifica  la proteína intimina y del gen hIyA codificante de  hemolisina, los cuales generaron productos de 259, 384 y 534 pb. En la segunda PCR se detectaron los genes de la sub-unidad A de las shigatoxinas stx1, stx2, incluidas las variantes de stx2. con amplicones de 180 y 255 pb. En la tercera se utilizaron iniciadores para stx1, stx2, eaeA y hIyA. Se determinó la selectividad de los iniciadores con cepas STEC, ATCC y se detectó hasta 1 UFC, lo cual demuestra su alta sensibilidad.