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Search Results: 1 - 10 of 11165 matches for " Claudia Urbina "
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Chiral Pt/ZrO2 Catalysts. Enantioselective Hydrogenation of 1-phenyl-1,2-propanedione
Claudia Urbina,Cristian Campos,Gina Pecchi,Carmen Claver,Patricio Reyes
Molecules , 2010, DOI: 10.3390/molecules15053428
Abstract: The enantioselective hydrogenation of 1-phenyl-1,2-propanedioneover Pt colloids stabilized with (R,S)-4,5-dihydro-4,5-diphenyl-2-(6-cyanopyridinyl)imidazoline (CI) supported on a meso-structured ZrO2 under a pressure of 40 bar of H2 at 298 K has been investigated. The metal loading in all catalysts was 1 wt%. The effect of the amount of chiral modifier on the metal particle size and on the catalytic behavior was analyzed. It was found that as the CI/Pt molar ratio increases from 2.5 to 3.5 the Pt crystal size decreases from 3.0 to 1.8 nm. All catalysts were very active in the studied reaction, with the most active one being the catalyst with smaller Pt particles, whereas the selectivity is higher in those catalysts with larger chiral modified Pt metal particles.
Excretion Products of Shigella dysenteriae and Apoptotic Cell Death on Chick Embryo Muscle Tissue
Alvarez,Marco; Urbina,Gidalia; Müller,Claudia; Perdomo,Lourdes;
International Journal of Morphology , 2007, DOI: 10.4067/S0717-95022007000300024
Abstract: the aim of this study was to evaluate the acute cell injury of excretion products present in culture filtrate from shigella dysenteriae in both whole lower limb of chick embryo ex vivo and myoblasts cells developed in hanging-drop cultures in vitro. three controls were defined: a) tyrode's solution b) brain-heart broth infusion (ccc) and c) supernatant not toxigenic of e.coli 0157:h7. shigella dysenteriae were culture for 24 hours and the excretion products were obtained after centrifugation of the culture. after lh of treatment, the morphologic changes in limbs treated with raw filtrate were evaluated through histopathological examination of sections stained with hematoxylin-eosin (h&e-stain) and gomori's trichrome by image analysis techniques. quantification of apoptotic cells was measured by an enzyme-linked immunoassay tunel. the morphological feature of apoptosis were evaluated in culture myoblasts. in contrast with controls, the longitudinal section on treated thigh of chick embryo limb-buds show atrophy muscle tissue, detachment of few fibers, 57,14% decrease in the number of cells, and loss of collagen substrate. apoptotic index percent increase and mitotic index decrease in response to excretion products were observed, but were not significant. membrane blebbing, vacuolation, small aggregates of chromatin around the nucleus and loss of cell adhesion were observed. culture filtrate from shigella dysenteriae produced cytotoxic effect on cell of muscle fibers with acute cell injuries suspected to be related to the apoptotic cell death
ENANTIOSELECTIVE HYDROGENATION OF 1-PHENYL-1,2-PROPANODIONE ON Pt/ ZrO2 CATALYSTS
URBINA,CLAUDIA; PECCHI,GINA; CAMPOS,CRISTIAN; REYES,PATRICIO;
Journal of the Chilean Chemical Society , 2010, DOI: 10.4067/S0717-97072010000100007
Abstract: the enantioselective hydrogenation of 1-phenyl-1,2-propanedione at 298k and pressure of 40 bar of h2 over zirconia supported pt catalysts has been studied. three different zirconia were prepared : i) zro2- p obtained by a precipitation procedure from zrocl2 ii) mszro2 obtained by a sol-gel procedure using cetryltrimethylammonium bromide (ctmabr) as surfactant to get a mesostructured solid iii) cntszro2 obtained after impregnation of carbon nanotubes with zro(no)3 followed by pyrolisis and calcination. pt (1 wt%) was introduced on the support by impregnation of an aqueous solution of h2ptcl6. the catalysts were characterized by nitrogen adsorption-desorption isotherms at 77 k, hydrogen chemisorption, xrd and tem techniques. the reactions were carried out in a stainless steel batch reactor using cyclohexane as solvent and cinchonidine as chiral modifier. the presence of cd in the reaction medium is necessary to induce an enantiomeric excess (ee) of the desired product r-1phenyl-1 hydroxi-2-propanone. in all the studied systems, the relation between the enantioselectivity and the cd concentration added in situ exhibits a bell type curve; indicative of the importance of competitive adsorption between the modifier and the substrate on the catalyst surface. on the other hand, confinement effect led to an important enhancement in the activity in those catalysts supported on mesostructured supports, mainly in the pt/cntszro2 catalyst.
Excretion Products of Shigella dysenteriae and Apoptotic Cell Death on Chick Embryo Muscle Tissue Producto de Excreción de Shigella dysenteriae y la Muerte Celular por Apoptosis en Tejido Muscular de Embrión de Pollo
Marco Alvarez,Gidalia Urbina,Claudia Müller,Lourdes Perdomo
International Journal of Morphology , 2007,
Abstract: The aim of this study was to evaluate the acute cell injury of excretion products present in culture filtrate from Shigella dysenteriae in both whole lower limb of chick embryo ex vivo and myoblasts cells developed in hanging-drop cultures in vitro. Three controls were defined: a) Tyrode's solution b) brain-heart broth infusion (CCC) and c) supernatant not toxigenic of E.coli 0157:H7. Shigella dysenteriae were culture for 24 hours and the excretion products were obtained after centrifugation of the culture. After lh of treatment, the morphologic changes in limbs treated with raw filtrate were evaluated through histopathological examination of sections stained with hematoxylin-eosin (H&E-stain) and Gomori's trichrome by image analysis techniques. Quantification of apoptotic cells was measured by an enzyme-linked immunoassay TUNEL. The morphological feature of apoptosis were evaluated in culture myoblasts. In contrast with controls, the longitudinal section on treated thigh of chick embryo limb-buds show atrophy muscle tissue, detachment of few fibers, 57,14% decrease in the number of cells, and loss of collagen substrate. Apoptotic index percent increase and mitotic index decrease in response to excretion products were observed, but were not significant. Membrane blebbing, vacuolation, small aggregates of chromatin around the nucleus and loss of cell adhesion were observed. Culture filtrate from Shigella dysenteriae produced cytotoxic effect on cell of muscle fibers with acute cell injuries suspected to be related to the apoptotic cell death El objetivo del presente trabajo ha sido evaluar el da o celular agudo generado por el producto de excreción de Shigella dysentenae sobre el tejido muscular del miembro inferior de embrión de pollo, así como sobre los mioblastos obtenidos a partir del cultivo de explantes de tejido muscular desarrollado en gota pendiente. Tres controles fueron definidos: a) solución de tiroide b) caldo de infusión cerebro-corazón (CCC), c) producto de excreción bacteriano no toxigénico de E. coli 0157:H7. El producto de excreción fue obtenido a partir de la centrifugación y filtrado del medio de cultivo de Shigella dysentenae con 24 horas de crecimiento. Luego de una hora de tratamiento, los cambios morfológicos del tejido muscular fueron evaluados a través del examen histopatológico, con técnicas de análisis de imágenes sobre cortes te idos con hematoxilina-eosina (H&E) y Tricrómico de Gomori. El ensayo enzimático TúNEL fue utilizado para evaluar el índice de apoptosis. Se ales morfológicas de muerte celular fueron evaluadas en miob
El producto de excreción de shigella dysenteriae induce cariólisis y calcificación en el tejido hepático de embrión de pollo. "ex vivo" e "in vitro"
Marco Alvarez,Gidalia Urbina,Claudia Müller,Lourdes Perdomo
Revista de la Facultad de Medicina , 2006,
Abstract: Objetivos: el objetivo de este estudio fue caracterizar histológica y morfométricamente alteraciones "ex vivo" e "in vitro" del tejido hepático de embrión de pollo causadas por el producto de excreción de Shigella dysenteriae. Métodos: el tejido hepático de embrión de pollo de 8 días de desarrollo, "ex vivo", y las células hepáticas cultivadas por la técnica de gota pendiente, "in vitro", fueron utilizados. Ambos sistemas fueron sumergidos en el producto de excreción obtenido a partir del sobrenadante del cultivo de la cepa Shigella dysenteriae tipo I. Tres controles fueron definidos: a) solución Tyrode, b) caldo de infusión de cerebro-corazón (CCC), c) producto de excreción no toxigénico de la bacteria E. coli O157:H7. Después de una hora de tratamiento los tejidos y las células fueron fijadas en formol zinc. Los hallazgos histológicos fueron obtenidos en cortes te idos con hematoxilina eosina y Von Kossá. Para llevar a cabo el análisis morfométrico se hizo uso de técnicas de morfología microscópica de análisis de imágenes con el programa ImagenJ versión 1.36. Resultados: el tejido hepático de embrión de pollo "ex vivo" tratado con el producto de excreción de Shigella dysenteriae mostró, respecto al control: la pérdida en el arreglo de las células endoteliales, núcleos con pérdida del contenido nuclear, espacios sinusoidales de mayor tama o y presencia de fosfatos de calcio sobre la región de las células endoteliales que recubren a la vena central. Las células hepáticas tratadas "in vitro" mostraron: forma estrecha, abundancia de vesículas de lípidos de mayor tama o, reducción significativa del número de pixels por área nuclear sobre la escala de grises entre 85 y 168 e incremento de la región de los blancos sobre la escala de grises 169-255, respecto al control CCC, evidenciado a través del histograma. Conclusiones: el producto de excreción de Shigella dysenteriae induce vaciado del contenido nuclear y deposición de fosfatos de calcio, lo cual se traduce en un fenómeno de cariólisis y formación de centros de calcificación respectivamente. Ambos fenómenos pudieran ser definidos como signos de hepatotoxicidad inducidos por el producto de excreción de Shigella dysenteriae. Objective: The aim of this study was to characterize, histologicaly and morphometricaly the chick embryo hepatic tissue alteration caused by the action of excretion products of Shigella dysenteriae "ex vivo" and "in vitro". Methods: Hepatic tissue of 8 day-old chick embrion development, "ex vivo", and hepatic cell culture "in vitro" in Hanging-drop techniques were used. Both systems wer
ENANTIOSELECTIVE HYDROGENATION OF 1-PHENYL-1,2-PROPANODIONE ON Pt/ ZrO2 CATALYSTS
CLAUDIA URBINA,GINA PECCHI,CRISTIAN CAMPOS,PATRICIO REYES
Journal of the Chilean Chemical Society , 2010,
Abstract: The enantioselective hydrogenation of 1-phenyl-1,2-propanedione at 298K and pressure of 40 bar of H2 over zirconia supported Pt catalysts has been studied. Three different zirconia were prepared : i) ZrO2- P obtained by a precipitation procedure from ZrOCl2 ii) MSZrO2 obtained by a sol-gel procedure using cetryltrimethylammonium bromide (CTMABR) as surfactant to get a mesostructured solid iii) CNTsZrO2 obtained after impregnation of carbon nanotubes with ZrO(NO)3 followed by pyrolisis and calcination. Pt (1 wt%) was introduced on the support by impregnation of an aqueous solution of H2PtCl6. The catalysts were characterized by nitrogen adsorption-desorption isotherms at 77 K, hydrogen chemisorption, XRD and TEM techniques. The reactions were carried out in a stainless steel batch reactor using cyclohexane as solvent and cinchonidine as chiral modifier. The presence of CD in the reaction medium is necessary to induce an enantiomeric excess (ee) of the desired product R-1phenyl-1 hydroxi-2-propanone. In all the studied systems, the relation between the enantioselectivity and the CD concentration added in situ exhibits a bell type curve; indicative of the importance of competitive adsorption between the modifier and the substrate on the catalyst surface. On the other hand, confinement effect led to an important enhancement in the activity in those catalysts supported on mesostructured supports, mainly in the Pt/CNTsZrO2 catalyst.
ANTIOXIDANT PROPERTIES OF LIGNANS AND FERULIC ACID FROM THE RESINOUS EXUDATE OF LARREA NITIDA
RENé TORRES,FRANCISCO URBINA,CLAUDIA MORALES,BRENDA MODAK
Journal of the Chilean Chemical Society , 2003,
Abstract: From the resinous exudate of twigs end leaves of Larrea nitida, two lignans nor isoguaiacine 1 and meso-nor-dihydroguaiaretic acid 2 and ferulic acid 3 were isolated. The antioxidant activities of resin and pure compounds were assesed by bleaching of the ABTS derived radical-cation
Caracterización del Traumatismo Dentoalveolar que Afecta a los Tejidos de Soporte en Dientes Temporales
ávila Rivera,Claudia; Cueto Urbina,Alfredo; González Ríos,Jenniffer;
International journal of odontostomatology , 2012, DOI: 10.4067/S0718-381X2012000200007
Abstract: the purpose of pursuing this research is to evaluate the distribution of dentoalveolar trauma in time by gender, age, etiology, where the injury occurs, diagnosis of trauma, and treatment affected teeth done. the sample corresponds to 207 children benefiting from pediatric dentist referral center simon bolivar, ages 1 to 7 years who suffered dentoalveolar trauma of the anterior teeth during the years 2005-2007 which corresponds according to the classification proposed by andreasen, injuries affecting the tooth supporting tissue, including: subluxation, lateral luxation, intrusive luxation, extrusive luxation and avulsion. the results obtained allow us to observe a higher percentage of trauma to the male gender with 60% being the most common age between 4 and 6, the upper central incisors are the teeth most affected (39-40%). the most common etiology corresponds to a 25% fall, this being more prevalent in school or kindergarten (20%). as for the diagnosis of dentoalveolar trauma subluxation the majority are present in 53% of cases. the control and indication is the treatment most used in these dentoalveolar traumas.
ANTIOXIDANT PROPERTIES OF LIGNANS AND FERULIC ACID FROM THE RESINOUS EXUDATE OF LARREA NITIDA
TORRES,RENé; URBINA,FRANCISCO; MORALES,CLAUDIA; MODAK,BRENDA; MONACHE,FRANCO DELLE;
Journal of the Chilean Chemical Society , 2003, DOI: 10.4067/S0717-97072003000300012
Abstract: from the resinous exudate of twigs end leaves of larrea nitida, two lignans nor isoguaiacine 1 and meso-nor-dihydroguaiaretic acid 2 and ferulic acid 3 were isolated. the antioxidant activities of resin and pure compounds were assesed by bleaching of the abts derived radical-cation
El producto de excreción de shigella dysenteriae induce cariólisis y calcificación en el tejido hepático de embrión de pollo. "ex vivo" e "in vitro"
Alvarez,Marco; Urbina,Gidalia; Müller,Claudia; Perdomo,Lourdes; Ruiz,Andrés;
Revista de la Facultad de Medicina , 2006,
Abstract: objective: the aim of this study was to characterize, histologicaly and morphometricaly the chick embryo hepatic tissue alteration caused by the action of excretion products of shigella dysenteriae "ex vivo" and "in vitro". methods: hepatic tissue of 8 day-old chick embrion development, "ex vivo", and hepatic cell culture "in vitro" in hanging-drop techniques were used. both systems were embedded in the excretion products of shigella dysenteriae obtained from the supernatant of shigella dysenteriae type i. three controls were defined: a) tyrode solution, b) brain-heart broth infusion (ccc), c) supernatant of e. coli 0157:h7, not toxigenic. after 1 h of treatment, the tissue and cells were fixed in formol-zinc. histological findings were obtained with hematoxylin eosin and von kossá staining. in order to carry out the morphometricaly examination, an imagen analysis in microscopic morphology techniques with imagenj 1.36 version was applied. results: the embryonic hepatic tissue treated, "ex vivo", with excretion products of shigella dysenteriae show: a loss in the arrangement of the endothelial cells, sinusoidal space was more open, nucleus with loss of the nuclear content and presence of calcium phosphates on the endothelial cells that covered the central vein, with regard to controls groups. the hepatic cells treated "in vitro" showed: narrow forms, abundance of lipid vesicles of great size, significantly reduction of pixels per nuclear area on grey scale between 85-168 and increase of the white region on grey scale between 169-255, when compared to control groups. conclusions: the excretion products of shigella dysenteriae induced karyolysis and calcified center formation. both phenomena probably defined signs of excretion product of shigella dysenteriae injury on embryonic hepatic tissue.
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