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Search Results: 1 - 10 of 160503 matches for " Manuel F. Varela "
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Biochemistry of Bacterial Multidrug Efflux Pumps
Sanath Kumar,Manuel F. Varela
International Journal of Molecular Sciences , 2012, DOI: 10.3390/ijms13044484
Abstract: Bacterial pathogens that are multi-drug resistant compromise the effectiveness of treatment when they are the causative agents of infectious disease. These multi-drug resistance mechanisms allow bacteria to survive in the presence of clinically useful antimicrobial agents, thus reducing the efficacy of chemotherapy towards infectious disease. Importantly, active multi-drug efflux is a major mechanism for bacterial pathogen drug resistance. Therefore, because of their overwhelming presence in bacterial pathogens, these active multi-drug efflux mechanisms remain a major area of intense study, so that ultimately measures may be discovered to inhibit these active multi-drug efflux pumps.
Assessment of Student Skills for Critiquing Published Primary Scientific Literature Using a Primary Trait Analysis Scale
Manuel F. Varela,Marvin M. F. Lutnesky,Marcy P. Osgood
Journal of Microbiology & Biology Education , 2005, DOI: 10.1128/jmbe.v6i1.80
Abstract: Instructor evaluation of progressive student skills in the analysis of primary literature is critical for the development of these skills in young scientists. Students in a senior or graduate-level one-semester course in Immunology at a Masters-level comprehensive university were assessed for abilities (primary traits) to recognize and evaluate the following elements of a scientific paper: Hypothesis and Rationale, Significance, Methods, Results, Critical Thinking and Analysis, and Conclusions. We tested the hypotheses that average recognition scores vary among elements and that scores change with time differently by trait. Recognition scores (scaled 1 to 5), and differences in scores were analyzed using analysis of variance (ANOVA), regression, and analysis of covariance (ANCOVA) (n = 10 papers over 103 days). By multiple comparisons testing, we found that recognition scores statistically fell into two groups: high scores (for Hypothesis and Rationale, Significance, Methods, and Conclusions) and low scores (for Results and Critical Thinking and Analysis). Recognition scores only significantly changed with time (increased) for Hypothesis and Rationale and Results. ANCOVA showed that changes in recognition scores for these elements were not significantly different in slope (F1,16 = 0.254, P = 0.621) but the Results trait was significantly lower in elevation (F1,17 = 12.456, P = 0.003). Thus, students improved with similar trajectories, but starting and ending with lower Results scores. We conclude that students have greatest difficulty evaluating Results and critically evaluating scientific validity. Our findings show extant student skills, and the significant increase in some traits shows learning. This study demonstrates that students start with variable recognition skills and that student skills may be learned at differential rates. Faculty can use these findings or the primary trait analysis scoring scale to focus on specific paper elements for which they desire to improve recognition.
Facing a Shift in Paradigm at the Bedside?  [PDF]
Borja Vargas, Manuel Varela
International Journal of Clinical Medicine (IJCM) , 2013, DOI: 10.4236/ijcm.2013.41008
Abstract:

Our entire medical framework is based on the concept of disease, understood as a qualitative departure from normality (health) with a structural substrate (lesion), and usually an identifiable cause (aetiology). This paradigm is loaded with problems, some of which are discussed in the text. Nevertheless, we study, diagnose and treat diseases, and while often painfully conscious of the dysfunctionalities of this scheme, we can hardly imagine how we could practice medicine otherwise. However, most of the recent developments in basic sciences, and most notably in Immunology, Genetics and -omics, are inconsistent with this “health/disease” paradigm. The emerging scenario is that of complex networks, more in the spirit of Systems Biology. In these settings the qualitative difference between health and disease loses its meaning, and the whole discourse becomes progressively irreducible to our conventional clinical categories. As clinical research stagnates while basic sciences thrive, this gap is widening, and a change in the prevailing paradigm seems unavoidable. However, all our clinical judgments (including Bayesian reasoning and Evidence Based Medicine) are rooted in the disease/health dichotomy, and one can hardly conceive how they could work without it. The shift in paradigm will not be easy, and certain turmoil is to be expected.

Modulation of Bacterial Multidrug Resistance Efflux Pumps of the Major Facilitator Superfamily
Sanath Kumar,Mun Mun Mukherjee,Manuel F. Varela
International Journal of Bacteriology , 2013, DOI: 10.1155/2013/204141
Abstract: Bacterial infections pose a serious public health concern, especially when an infectious disease has a multidrug resistant causative agent. Such multidrug resistant bacteria can compromise the clinical utility of major chemotherapeutic antimicrobial agents. Drug and multidrug resistant bacteria harbor several distinct molecular mechanisms for resistance. Bacterial antimicrobial agent efflux pumps represent a major mechanism of clinical resistance. The major facilitator superfamily (MFS) is one of the largest groups of solute transporters to date and includes a significant number of bacterial drug and multidrug efflux pumps. We review recent work on the modulation of multidrug efflux pumps, paying special attention to those transporters belonging primarily to the MFS. 1. Introduction Drug and multidrug resistant bacterial pathogens that are causative agents of infectious disease constitute a serious public health concern. Bacterial multidrug efflux pump systems of the major facilitator superfamily (MFS) and resistance-nodulation-cell division (RND) superfamily represent common mechanisms for bacterial resistance to antimicrobial agents. As such these bacterial transporters make suitable targets for modulation in order to restore the clinical efficacy of relevant chemotherapeutic antibacterial agents. Here, we briefly review the drug transporter systems of the MFS (and to a lesser extent the RND superfamily) and discuss their modulation via regulation of expression and efflux pump transport inhibition. 2. Bacteria and Pathogenesis Bacteria are unicellular, microscopic living organisms that are rod shaped, ball shaped, or spiral shaped when observed under the microscope. Most bacteria are not harmful; rather, they aid in food preparation and digestion, compete with pathogens, provide vitamins to the body, are useful for basic and applied research purposes, and are important in biotechnology. However, less than one percent of the bacteria of different types are responsible for causing bacterial infections. Bacterial cells are capable of quickly reproducing and releasing chemicals and toxins; pathogenic bacteria can cause damage to cells and tissues in the body and cause clinical disease. Some of the common diseases and infections caused by pathogenic strains of bacteria include food poisoning caused by Escherichia coli and Salmonella [1–6], gastritis and ulcers caused by Helicobacter pylori [7], the sexually transmitted disease gonorrhea caused by Neisseria gonorrhoeae [8], meningitis caused by N. meningitides [9], skin infections like boils, cellulitis,
La polémica construcción del edificio del Banco de Espa a en Santiago: Peripecias de postguerra
Corral Varela, Juan Manuel
Cuadernos de Estudios Gallegos , 1995,
Abstract: Not available. No disponible.
Aplicación de la teoría y método de análisis del arte prehistórico de C. Alonso del Real a Auga da Laxe, Gondomar, Pontevedra, roca con grabados de la Edad del Bronce en Galicia
Vázquez Varela, José Manuel
Trabajos de Prehistoria , 1994,
Abstract: The epistemology and methodology concepts of professor C. Alonso del Real (1914-1993) are applied to the study of Auga da Laxe I, rock with Bronze Age engravings in North-west Spain. The holistic perspective provides new data about the function and meaning of engravings of arms in the Bronze Age. Auga da Laxe seems to be a place for holding warrior aggregation rituals. Se aplican las concepciones epistemológicas y metodológicas del profesor C. Alonso del Real (1914-1993) al estudio de Auga da Laxe I, yacimiento de arte rupestre de la Edad del Bronce en el Noroeste de la Península Ibérica. Su enfoque holístico resulta eficaz y aporta nuevos datos sobre la función y el significado de los grabados de armas de la Edad del Bronce. Auga da Laxe puede ser un lugar de celebración de rituales de agregación de guerreros.
Aspectos metodológicos y prácticos en la formación de los aspirantes a Doctores en Ciencias Médicas: Resultados preliminares
Trinchet Soler,Rafael Manuel; Trinchet Varela,Carlos; García,Rita Concepción; Vázquez Fernández,Rafael; Rodríguez Expósito,Félix; Piriz Assa,Alberto Rubén;
Educaci?3n M??dica Superior , 2009,
Abstract: objectives: to assess the results from a project aimed to accelerate the training of medical sciences doctors using matters answering to prioritized problems in health field, and to show preliminary results achieved with a diploma designed for sciences doctors candidates. methods: it is based on a different organizing and methodological strategy from the involvement of a staff of different national entities, making first an individual diagnosis of candidate to obtain an individual advice and at the same time, to define a general training program where in the doctorate development process basic subject matters were given. results: the predominating age group was that between 30 and 41 years (46%), figure of professional-master increased from 5 to 14, 10 of them reached the teaching category, and 7 improved it, the figure of branch projects increases to 14, prior to intervention 18 candidates had approved their subject matter in provincial scientific council, nowadays are 39 in total with an increase of 21 subject matter. at beginning of intervention the minimum of approved matters was of 6, today 28 have a minimum of approved matters of 28, and 22 a minimum of subject matter finished. when research was designed the total of candidates was of 5, after intervention it is of 37, in the same way, only two had made the introduction and the first chapter, now are 16 who achieved this step. conclusions: methodology used has yields satisfactory results in training process of health sciences doctors.
Multidrug Efflux Pumps from Enterobacteriaceae, Vibrio cholerae and Staphylococcus aureus Bacterial Food Pathogens
Jody L. Andersen,Gui-Xin He,Prathusha Kakarla,Ranjana KC,Sanath Kumar,Wazir Singh Lakra,Mun Mun Mukherjee,Indrika Ranaweera,Ugina Shrestha,Thuy Tran,Manuel F. Varela
International Journal of Environmental Research and Public Health , 2015, DOI: 10.3390/ijerph120201487
Abstract: Foodborne illnesses caused by bacterial microorganisms are common worldwide and constitute a serious public health concern. In particular, microorganisms belonging to the Enterobacteriaceae and Vibrionaceae families of Gram-negative bacteria, and to the Staphylococcus genus of Gram-positive bacteria are important causative agents of food poisoning and infection in the gastrointestinal tract of humans. Recently, variants of these bacteria have developed resistance to medically important chemotherapeutic agents. Multidrug resistant Escherichia coli, Salmonella enterica, Vibrio cholerae, Enterobacter spp., and Staphylococcus aureus are becoming increasingly recalcitrant to clinical treatment in human patients. Of the various bacterial resistance mechanisms against antimicrobial agents, multidrug efflux pumps comprise a major cause of multiple drug resistance. These multidrug efflux pump systems reside in the biological membrane of the bacteria and actively extrude antimicrobial agents from bacterial cells. This review article summarizes the evolution of these bacterial drug efflux pump systems from a molecular biological standpoint and provides a framework for future work aimed at reducing the conditions that foster dissemination of these multidrug resistant causative agents through human populations.
La alta monta a de los Andes del norte: el páramo, un ecosistema antropogénico
Varela, L. F.
Pirineos : Revista de Ecología de Monta?a , 2008,
Abstract: Current characteristics of Colombian páramos are closely related with the human presence; the history of this relation, based on evidence from climatological, palinological and cartographical studies, suggest interesting conclusions for ecosystem conservation and the surrounding Andean forests. The first páramo interventions were sporadic; later, the human imprint tended towards ritualistic livelihoods, and it is in the colonial times when dynamic transformation occurred, extending páramos both altitudinally and latitudinally. Today, in order to inform conservation policy it is important to keep in mind how the human presence influences the ecosystem transformation, to manifest Andean mountains’ management strategies and policies with a string of facts of the human livelihood and the natural history of the mountains in tropical America. Las características actuales de los páramos colombianos se relacionan estrechamente con la presencia humana; la historia de esta relación, sustentada en evidencias de estudios climatológicos, palinológicos y cartográficos, sugiere interesantes conclusiones para la conservación de este ecosistema y los bosques andinos que lo circundan. Las primeras intervenciones en el páramo eran esporádicas; posteriormente la huella humana se orientó hacia la vida ritual y es realmente en la época de la colonia donde se interviene en su dinámica de transformación, extendiendo el páramo tanto altitudinal como latitudinalmente. Hoy en día, para las directrices de conservación es importante tener en cuenta cómo influye la presencia humana en la transformación de los ecosistemas; manifestando en las políticas y estrategias del manejo de las monta as andinas un hilo acorde con la realidad vivida entre los humanos y la historia natural de las monta as del trópico americano.
Sistemas cambiarios: una visión desde la actualidad
Félix Varela Parache
Análisis Económico , 2004,
Abstract: En los últimos a os la evolución del sistema cambiario de los países más desarrollados se ha orientado hacia una flotación acompa ada de políticas monetarias regladas, ejercidas por bancos centrales independientes. En los países en desarrollo la solución es menos uniforme y la teoría de la bipolaridad constituye una simplificación excesiva no suficientemente respaldada por la realidad o por la teoría. Algunos países emergentes, con mayor desarrollo económico e institucional, se encuentran en el camino de aprender a flotar , a semejanza de los países desarrollados. Para el resto, la mejor alternativa es un régimen cambiario intermedio, que tenga en cuenta la experiencia de las crisis recientes.
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