Sample records for CAPA DESIERTA (TRANSISTORES) (depletion layer)
from WorldWideScience.org

Sample records 1 - 19 shown.



1

UN MODELO DEL MECANISMO DE ENTRADA DE LOS ROTAVIRUS A LA CÉLULA HOSPEDERA/ A model for the mechanism of entry of rotaviruses into the host cell

Acosta L, Orlando; Calderón, Martha N; Moreno, Liz P; Guerrero, Carlos A
2009-04-01

Resumen en español Antecedentes. La infección rotaviral es causa principal de gastroenteritis aguda severa en niños menores de cinco años. La capa protéica externa de la partícula viral está implicada en las interacciones iniciales virus-superficie celular. El mecanismo rotaviral de unión y entrada a la célula parece ser un proceso de múltiples pasos donde las proteínas rotavirales VP4 y VP7 interaccionan con diferentes moléculas de la superficie celular. Objetivo. Proponer un me (mas) canismo de entrada de rotavirus a la célula que incorpore la actividad de la proteína disulfuro isomerasa (PDI). Material y métodos. Utilizando bases de datos electrónicas, se realizó una búsqueda de literatura original y de revisión publicada entre 1990 y 2009 sobre moléculas de la superficie rotaviral o celular participantes en el proceso de entrada del virus. El análisis de los resultados enfatizó las bases moleculares y celulares de las interacciones temporo-espaciales de las proteínas virales y las moléculas de unión/receptoras de la célula. Resultados. Se encontró fundamentos moleculares y celulares para incorporar la actividad de PDI a un mecanismo coherente de vías secuenciales o alternativas previas a la penetración viral. Se propone un mecanismo en que interaccionan las proteínas virales VP4, VP6 y VP7 con las moléculas de la superficie celular ácido siálico, integrinas, Hsc70 y PDI en un proceso endocítico caveola/“raft”-dependiente, caveolina/clatrina-independiente, dinamina-dependiente y sensible a depleción de colesterol. Conclusión. Se amplía el concepto de múltiples pasos en el proceso de entrada de rotavirus, donde la participación de PDI podría ser un blanco potencial de la acción de inhibidores de grupos tiol/disulfuro. Resumen en inglés Background. Rotavirus infection is the leading single cause of severe acute gastroenteritis in children under five years of age. The outermost layer of the triple-layered protein capsid of the non-enveloped virus particle has been involved in initial interactions between virus and host cell surface. The rotavirus mechanism for cell attachment and entry seems to be a multistep process in which outermost layer virus proteins VP4 and VP7 interact with different cell surface (mas) molecules. Objective. To propose a mechanism for rotavirus entry to the host cell incorporating the protein disulfide isomerase (PDI) activity. Materials and methods. A systematic search for original and review literature published from 1990 to 2009 on rotavirus and cell surface molecules participating in virus entry process was conducted through the use of electronic Databases. The analysis of the published results emphasized the molecular and cellular bases of time and space interactions between virus proteins and cell surface attachment and receptor molecules. Results. We found molecular and cellular bases for incorporating PDI within a coherent mechanism involving sequential or alternative paths previous to virus penetration. A mechanism is proposed in which virus proteins VP4, VP6 and VP7, and cell surface sialico acid, integrins, Hsc70, and PDI interact as part of a caveola/ raft-mediated endocytic process that is characterized by its caveolin and clathrin independence, dynamin dependence, and sensitivity to cholesterol depletion. Conclusions. The rotavirus entry mechanism appears to be a complex multistep process in which the path using PDI could be a potential target for antiviral agents reacting with thiol/disulfide groups.

Scientific Electronic Library Online (Spanish)

2

Taninos de diferentes especies vegetales en la prevención del fotoenvejecimiento

González Fresneda, Yulady; Peña Sánchez, Marisol; Sánchez Álvarez, Rosa; Santana, Jorge Luis
2001-03-01

Resumen en español La utilización de algunas sustancias naturales, en específico estructuras polifenólicas como las catequinas oligoméricas y flavonoides, ha demostrado ser una fuente de protección para el organismo. Son reconocidas sus propiedades antimicrobianas, antioxidantes, fotoprotectoras, así como inhibidores de proteasas como la elastasa. Dada la similitud estructural, fueron estudiados los taninos vegetales condensados de diferentes especies forestales a saber: pino, casuari (mas) na, mimosa, conos de pinos, eucalipto y soplillo. En los últimos años se ha prestado especial atención al estudio de nuevas sustancias con características fisicoquímicas capaces de prevenir trastornos que conducen a mutaciones cutáneas provocadas por las radiaciones ultravioletas; por causa fundamentalmente del incremento de la contaminación ambiental y el desgaste de la capa de ozono. El objetivo de este trabajo fue determinar la capacidad fotoprotectora de los taninos y dilucidar su posible mecanismo de acción. Para ello se realizaron 3 técnicas: fotoprotección en bacterias (E. coli); capacidad antioxidante espontánea e inducida en homogenato de cerebro de rata y actividad antielastasa. En los resultados se observó que los taninos de todas las especies vegetales eran capaces de proteger a las bacterias contra el daño de las radiaciones ultravioletas, lo que coincide con una buena actividad antioxidante y antielastasa; resultaron menores estas 2 últimas para el eucalipto Resumen en inglés The use of some natural substances, specifically phenolic structures such as flavonoids and oligomeric catechines has proved to be a source of protection for the body. Their antimicrobial, antioxidant and photoprotective properties are well-known and they are also recognized as protease inhibitors such as elastase. Given their structural similarities, condensed tannins from various vegetal species, such as pine tree, casuarine, mimosa, pine cones, eucalyptus and soplillo (mas) were studied. In the last few years, special attention has been paid to the study of new substances with physical and chemical characteristics, capable of preventing disorders leading to skin mutations resulting from ultraviolet radiations mainly due to the increased environmental pollution and the depletion of the ozone layer. The objective of this paper was to determine the photoprotective capacity and the possible mechanism of action of tannins. To this end, 3 techniques were applied: photoprotection in bacteria (E. coli); spontaneous or induced antioxidant capacity in rat brain homogenate and antielastase activity. The results revealed that tannins from all vegetal species were able to protect bacteria against UV radiation, which coincides with a good antioxidant and antielastase activity. However, eucalyptus showed lower antioxidant and antielastase activity

Scientific Electronic Library Online (Spanish)

4

Soil water availability improved by site preparation in a Pinus halepensis afforestation under semiarid climate

Querejeta Mercader, José Ignacio; Roldán Garrigos, Antonio; Albaladejo Montoro, Juan; Castillo Sánchez, Victor Manuel
2001-08-01

Digital.CSIC (Spain)

5

Pliocene–Holocene evolution of depositional conditions in the eastern Mediterranean: Role of anoxia vs. productivity at time of sapropel deposition

Gallego-Torres, David; Martínez-Ruiz, Francisca; Paytan, Adina; Jimenez Espejo, Francisco J.; Ortega-Huertas, M.
2007-04-06

Digital.CSIC (Spain)

7

Petrogenesis of highly depleted peridotites and gabbroic rocks from the Mayarí-Baracoa Ophiolitic Belt (Eastern Cuba).

Marchesi, Claudio; Garrido, C. J.; Godard, Marguerite; Proenza, J. A.; Gervilla, Fernando; Blanco-Moreno, Jesús
2006-05-05

Digital.CSIC (Spain)

8

Origin of Pyroxenite–Peridotite Veined Mantle by Refertilization Reactions: Evidence from the Ronda Peridotite (Southern Spain)

Bodinier, Jean-Louis; Garrido, C. J.; Chanefo, Ingrid; Bruguier, Olivier; Gervilla, Fernando
2008-02-19

Digital.CSIC (Spain)

9
10

Migration and accumulation of ultra-depleted subduction-related melts in the Massif du Sud ophiolite

Garrido, C. J.; Marchesi, Claudio; Godard, Marguerite; Belley, France; Ferré, Eric
2009-06-01

Digital.CSIC (Spain)

12

Integrated geophysical-petrological modeling of the lithosphere and sublithospheric upper mantle: Methodology and applications

Afonso, Juan Carlos; Fernández, Manel; Ranalli, G.; Griffin, W. L.; Connolly, J. A. D.
2008-01-01

Digital.CSIC (Spain)

14
15

Fate of persistent organic pollutants in the water column: Does turbulent mixing matter?

Jurado, Elena; Zaldívar, José Manuel; Marinov, Dimitar; Dachs, Jordi
2007-06-25

Digital.CSIC (Spain)

16

Effect of upwelling pulses on excess carbohydrate synthesis as deduced from nutrient, carbon dioxide and oxygen profiles

Fraga Rodríguez, Fernando; Ríos, Aida F.; Pérez, Fiz F.; Estrada, Marta; Marrasé, Cèlia
1999-11-26

Digital.CSIC (Spain)

17

Consideraciones sobre la capa de ozono y su relación con el cáncer de piel/ The relationship between the ozone layer and skin cancer

Sánchez C, Francisca
2006-09-01

Resumen en inglés In the recent decades, a sustained increase in the worldwide incidence of skin cancer has been observed and Chile is not the exception. The most important risk factor is the exaggerated and repeated exposure to ultraviolet radiation coming from the sun. The ozone layer restricts the transmission of type B and C ultraviolet light. Since 1980, a sustained depletion of stratospheric ozone levels is occurring, specially in middle latitudes (-30 to ­60). Along with this deple (mas) tion, the amount of ultraviolet light that reaches the earth surface is increasing. This article reviews some basic concepts about the ozone layer and the association between its depletion and skin cancer. The general population should be informed about the risks of inadequate and exaggerated exposure to sunlight

Scientific Electronic Library Online (Spanish)

18

Basin-scale changes of total organic carbon profiles in the eastern South Atlantic

Fernández Pérez, Fíz; Fernández Ríos, Aida de la Aurora; Álvarez-Salgado, Xosé Antón; Doval, M. D.
2001-01-01

Digital.CSIC (Spain)

19

Aluminium depletion in NiCrAlY bond coatings by hot corrosion as a function

Mayoral Gastón, María del Carmen; Andrés Gimeno, José Manuel; Bona, M. T.; Higuera, V.; Belzunce, F. J.
2008-02-01

Digital.CSIC (Spain)