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Search Results: 1 - 10 of 199668 matches for " Zulma; Dávila-Vera "
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Metabolitos secundarios de líquenes de la zona nival de la Sierra Nevada de Mérida-Venezuela y su papel en la absorción de la radiación ultravioleta
Palacios-Prü, Ernesto,Mendoza-Brice?o, Rosa Virginia,Pe?a-Contreras, Zulma,Dávila-Vera, Delsy
Anales del Jardín Botánico de Madrid , 2008,
Abstract: Photochemical analyses of secondary compounds in lichens from the venezuelan andean snow zone were carried out in order to know the absorbance capacity of UV radiation at the UVA, UVB and UVC ranges and to determine its probable UV protective function. Spectrophotometric (UV) and fine layer chromatographic techniques (TLC) were utilized to separate and identify the compounds. UV radiation values were obtained from the Red Bioclimática del Parque Nacional Sierra Nevada de Mérida which constitutes a program supported by the University of Los Andes, Venezuela. Results indicated the existence of 22 species of lichens at the snow zone; 55% of these species showed a strong resistance to UVC radiation, 95% to UVB radiation, whereas the 100% revealed a strong resistance to UVA radiation. The substances that have the highest resistance to UVA and UVB radiation are characterized by having ester bonds among phenolic units depsids and constitute the most abundant products in lichens, whereas the substances having both ester and ether bonds among the two phenolic units depsidones revealed a higher capacity to absorb UVC radiation that could indicate a primitive origin. Se hicieron análisis fotoquímicos de compuestos secundarios presentes en líquenes de la zona nival andina venezolana con la finalidad de conocer su capacidad de absorber las radiaciones ultravioletas UVA, UVB y UVC e inferir en la probable función protectora de estos compuestos ante estas radiaciones. Para la separación e identificación de sustancias se utilizaron técnicas espectrofotométricas (UV) y técnicas de cromatografía de capa fina (TLC). Para el estudio climático de la zona nival se utilizaron registros de la Red Bioclimática del Parque Nacional Sierra Nevada de Mérida, Programa de la Universidad de Los Andes, Venezuela. Los resultados revelaron que, de las 22 especies encontradas, el 55% presentó una resistencia potencial a la radiación UVC, el 95% a la radiación UVB y el 100% a la radiación UVA. Entre las sustancias identificadas, las que presentaron mayor resistencia a las radiaciones UVA y UVB se caracterizan por presentar enlaces tipo éster entre las unidades fenólicas (dépsidos) y constituyen los productos más abundantes en estos líquenes. Mientras que, las sustancias con enlaces tipo éster y éter entre las dos unidades fenólicas (depsidonas), tienen alta capacidad de absorber radiación UVC, lo cual sugiere que el fenómeno de protección podría ser de origen primitivo.
Ultraestructura de las miofibrillas en cardiomiocitos durante el desarrollo embrionario tardío y postnatal temprano de ratón.
Nancy Jaimes-Méndez,Zulma Pe?a-Contreras,Delsy Dávila-Vera,Melisa Colmenares-Sulbarán
Bistua : Revista de la Facultad de Ciencias Básicas , 2011,
Abstract: En este estudio se describen por medio del análisis ultraestructural los cambios en la citodiferenciación de las miofibrillas en los cardiomiocitos del tejido cardiaco en desarrollo embrionario tardío y postnatal temprano de ratón. El proceso de diferenciación progresiva en diferentes espacios celulares de las miofibrillas, es una manifestación propia de las etapas estudiadas. En algunas células se observa la ultraestructura propia de las sarcómeras, con sus respectivas bandas Z, I, A y H, en contraste con otras miofibrillas que no se evidencian éstas estriaciones, posiblemente porque están en proceso de formación. En edades embrionarias las miofibrillas están separadas unas de otras por un espacio interfibrilar irregular; mientras que en edades postnatales, tienen una mejor organización y muchas de ellas están empaquetadas en masas confluentes y compactas que se fusionan para formar fibras largas, ramificadas y se disponen siguiendo el eje longitudinal de la célula, intercaladas con filas de mitocondrias. Esta conformación se relaciona con la forma alargada de los cardiomiocitos y con el aumento de la longitud de las miofibrillas; mientras que la presencia en el sarcoplasma de grandes áreas electrón- translucidas se reducen a medida que aumenta la maduración, producto de la diferenciación estructural de la síntesis, organización de las miofibrillas y otras organelas. Estos cambios morfológicos en la citoarquitectura son consecuencia de la adaptación del miocardio postnatal a las exigencias de trabajo poco después del nacimiento y además, están relacionados con los cambios circulatorios que ocurren en el periodo neonatal.
Effects of Aeromonas caviae co-cultured in mouse small intestine
Longa-Brice?o,Aurora; Pe?a-Contreras,Zulma; Dávila-Vera,Delsy; Mendoza-Brice?o,Rosa Virginia; Palacios-Prü,Ernesto;
Interciencia , 2006,
Abstract: the ultrastructural aspects generated by the interaction between two strains of aeromonas caviae with mouse intestinal mucosa are described. one of the strains was isolated from an asymptomatic patient and the other one from a patient with diarrhea. both strains were separately inoculated in closed cylinders of mouse small intestine and the whole preparations were incubated in eagle?s culture medium. the intestinal cylinders were divided into two groups, one was incubated for 24h and the other for 48h. samples of the co-cultures were processed for analysis using high resolution light microscopy and transmission electron microscopy. the strain isolated from the asymptomatic patient showed variable alterations in the intestinal mucosa, according to the different periods of incubation, whereas the one obtained from the patient with diarrhea always produced severe enteropathogenic effects
Experimental toxicity of Aeromonas spp. In mouse?s small intestine: Ultrastructural aspects
Longa-Brice?o,Aurora; Pe?a-Contreras,Zulma; Dávila-Vera,Delsy; Mendoza-Brice?o,osa Virginia; Palacios-Prü?,Ernesto;
Interciencia , 2008,
Abstract: ultrastructural aspects of mouse small intestinal tissue cultures infected with aeromonas spp. strains are described. high resolution light and transmission electron microscopy were used to assess the bacterial pathogenic mechanism, the ultrastructural changes that take place during the colonization of the intestinal tract and the interaction of aeromonas spp. with the host epithelium. after 24h of culture, chains of vesicles were seen on the outer surface of the aeromonas? membrane. the vesicles were also found on the enterocyte surface. after 48h of culture, lysis of the epithelial intestinal cells, mononuclear phagocytic cells, phagocytic eosinophils and phagocyted aeromonas were observed.
Investigación de Blastocystis sp. en agua de consumo humano en una población escolar de la zona rural del estado Mérida-Venezuela
Flores-Carrero,Ana Deixy; Pe?a-Contreras,Zulma; Dávila-Vera,Delsy; Colmenares-Sulbarán,Melisa; Mendoza-Brice?o,Rosa Virginia;
Kasmera , 2011,
Abstract: in order to determine the presence of blastocystis sp. in drinking water at a rural school in merida, 36 water samples were collected from natural sources that feed the distribution tank and faucets during the months of september, 2008, february and december, 2009, and may, 2010. samples were processed using the technique proposed by suresh et al. (2005). all samples were negative. these results suggest that the water was exempt from blastocystis or that the quantity of viable cysts present in the samples was very low, not permitting reproduction in the culture. this report suggests the importance of using more sensitive techniques to detect low amounts of the organism in drinking water. the study of student water consumption habits at the rural school showed that more than half the population consume boiled water; probably, they are aware that the water source has not been treated for drinking.
Da?o ultraestructural del intestino medio abdominal de Lutzomyia ovallesi (Ortiz) (Diptera: Psychodidae) ocasionado por Leishmania (Leishmania) amazonensis
NIEVES,ELSA; DáVILA - VERA,DELSY; PALACIOS-PRü,ERNESTO;
Parasitología latinoamericana , 2004, DOI: 10.4067/S0717-77122004000300005
Abstract: a study was done in the middle intestine of lutzomyia ovallesi infected with leishmania (leishmania) amzonensis. the females were examined seven days after infection by means of high resolution light microscopy and transmission electron microscopy. two kinds of epithelial cells, digestive and secretory, were observed in the middle intestine of l. ovallesi, in both control insects and in those infected. results showed changes in the cytoarchitecture of the intestine as a consequence of infection with l. (l.) amazonensis. there was a great increase in the diameter of the intestine, showing signs of cellular degeneration, such as partial or total loss of microvilli and the thickening of the basal layer of the whole portion of the intestine. epithelial cells showed damage in vacuoles and mitochondria, and epithelial waste was observable in the intestine. cellular damage in the middle intestine of l. ovallesi produced by infection with l. (l.) amazonensis is perhaps connected with lectin secretion and formation of gel, similar to that of a matrix, in the intestinal lumen. more studies are needed to clarify important aspects of the relationship between leishmania and the vector.
Da o ultraestructural del intestino medio abdominal de Lutzomyia ovallesi (Ortiz) (Diptera: Psychodidae) ocasionado por Leishmania (Leishmania) amazonensis ULTRASTRUCTURAL DAMAGE TO THE MIDDLE INTESTINE OF Lutzomyia ovallesi (Ortiz) (DIPTERA: PSYCHODIDAE) CAUSED BY Leishmania (Leishmania) amazonensis
ELSA NIEVES,DELSY DáVILA - VERA,ERNESTO PALACIOS-PRü
Parasitología latinoamericana , 2004,
Abstract: Se estudió el intestino medio abdominal de Lutzomyia ovallesi infectada con Leishmania (Leishmania) amazonensis. Las hembras se observaron a los siete días post- infección, utilizando microscopía de luz de alta resolución y microscopía electrónica de transmisión. Se distinguieron dos tipos de células epiteliales, células digestivas y células secretoras, en el intestino medio abdominal de L. ovallesi, tanto en los insectos controles como en flebotominos infectados. Los resultados muestran además, que L. ovallesi presentó alteraciones en la citoar-quitectura celular del intestino medio abdominal producto de la infección con L. (L.) amazonensis, observándose gran distensión del diámetro de la luz intestinal, degeneración de sus células, pérdida parcial o total de las microvellosidades y engrosamiento de la capa basal de toda la porción del intestino. Las células epiteliales presentaron degeneración vacuolar y mitocondrial y en la luz intestinal se observaron desechos epiteliales. El da o celular observado en el intestino medio abdominal de L. ovallesi, pueden tener relación con la secreción de lectinas y con la formación del gel observado, semejante a una matriz, en el lumen del intestino. Es necesario continuar los estudios para dilucidar aspectos importantes de la interrelación Leishmania-vector. A study was done in the middle intestine of Lutzomyia ovallesi infected with Leishmania (Leishmania) amzonensis. The females were examined seven days after infection by means of high resolution light microscopy and transmission electron microscopy. Two kinds of epithelial cells, digestive and secretory, were observed in the middle intestine of L. ovallesi, in both control insects and in those infected. Results showed changes in the cytoarchitecture of the intestine as a consequence of infection with L. (L.) amazonensis. There was a great increase in the diameter of the intestine, showing signs of cellular degeneration, such as partial or total loss of microvilli and the thickening of the basal layer of the whole portion of the intestine. Epithelial cells showed damage in vacuoles and mitochondria, and epithelial waste was observable in the intestine. Cellular damage in the middle intestine of L. ovallesi produced by infection with L. (L.) amazonensis is perhaps connected with lectin secretion and formation of gel, similar to that of a matrix, in the intestinal lumen. More studies are needed to clarify important aspects of the relationship between Leishmania and the vector.
TIPOLOGIA URBANA: O EXEMPLO DO ESTADO DO RIO DE JANEIRO
Miguel Angelo RIBEIRO,Vera Maria dvila CAVALCANTI
Revista ACTA Geográfica , 2011,
Abstract: This article intends to analyze the fluminense spatial organization, based upon a typology that will contemplate the urbanization rate of the state's municipalities and comprises the indexes of demographic dimension and urbanization rate. Choosing demographic dimension allows for a discriminative interpretation of both consumption and production within a municipality, due to the elected variable (population) and its proximity to the actual bulk of consumers. As for the choice of urbanization rate, it lies upon the acknowledgement that the bigger the ratio of urban population the greater will be the expression of urban activity - commerce, services and industry. The methodology used in constructing such typology consisted in matrically crossing the values of population (demographic dimension) and of the ratio between the latter and the urban population (urbanization rate). Thus, these matrical crossings led to the identification of three major sets of municipalities: urban, in transition to urban and rural.
METABOLISMO MITOCONDRIAL Y ULTRAESTRUCTURA DE MúSCULO ESQUELéTICO DE RATóN CON RESTRICCIóN CALóRICO PROTEICA
Ramírez,Luisa Maria; Dávila -Vera,Delsy; Palacios-Prü,Ernesto;
Revista chilena de nutrición , 2006, DOI: 10.4067/S0717-75182006000100007
Abstract: in this work, the method of permeabilization of muscular tissue with saponin was employed, which destroyed the sarcolemma but maintained the mitochondria "in situ". to create a model of mitochondrial pathology, a caloric-protein restriction (cpr) was produced in adult mice by reducing 50% the diet to fed animals for 15 days. determinations of oxygen consumption, adp/o ratio, total proteins, as well as enzymatic activities of respiratory chain complexes i and ii were performed. to evaluate the effect of saponin on muscular tissues under normal or cpr conditions, electron microscopy observations were done. results of the study showed that the animals in cpr group had loss of weight, reduced total proteins, diminished oxygen consumption, lower adp/o ratio in the presence of glutamate and succinate, and a notable decrement in the activity of complex i but without modifications of that of complex ii. electron microscopic observations demonstrates directs effects of cpr over the contractile apparatus of muscle fibers, such as, disorganization of sarcomeric structures and an important reduction of the myofilaments. on the other hand, saponin affected all cytomembranous systems
Estandarización del P.B.I. (Parental Bonding Instrument),versión adaptada a la población entre 16 y 64 a os del Gran Santiago Adapting the PBI (Parental Bonding Instrument) to the Greater Santiago Population Aged 16-64
Francisca Melis,María de los ángeles Dávila,Verónica Orme?o,Valeria Vera
Revista Chilena de Neuro-Psiquiatría , 2001,
Abstract: La presente investigación tuvo por objetivo estandarizar el cuestionario Parental Bonding Instrument, P.B.I (2), a la población de entre 16 y 64 a os de eda d del Gran Santiago. Este instrumento de medición psicológica está basado en la Teoría del Vínculo y mide la percepción del sujeto sobre las conductas y actitudes de sus cuidadores, para conocer la contribución parental en el apego y establecer el tipo de vínculo del sujeto. Se aplicó el cuestionario a una muestra de 542 personas, controlando las variables sexo, edad y nivel socioeconómico (N.S.E.). Se realizó un análisis estadístico de los resultados, evaluando las características psicométricas del test, obteniéndose normas generales y diferenciales según las variables estudiadas. Los resultados confirman las propiedades psicométricas del PBI, como un instrumento confiable para la medición de la contribución parental en el apego, estableciendo los diferentes tipos de vínculos Objective of this research was to adapt the Parental Bonding Instrument (PBI) questionnaire to the Greater Santiago community aged 16 to 64 years old. This psychological assessment tool uses the Theory of Attachment to rate the subject's perception of his/her guardian's attitudes and behaviors. The tool also evaluates the level of parental attachment and the type of bond experienced by the subject. A sample of 542 subjects was tested and included sex, age and socioeconomic level variables. The general norms and differentials were obtained according to a statistical analysis of the results and to an evaluation of the psychometric characteristics of the test. The results confirmed that the psychometric characteristics of the PBI makes it a reliable tool to assess parental contribution to the parent/child relationship and to establish different types of bonds
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