Angelica Perez - Academia.edu (original) (raw)
Papers by Angelica Perez
Contemporary Clinical Trials Communications
Cancer Epidemiology, Biomarkers & Prevention, 2022
Background: Breast cancer is the most common cancer in women in the U.S. and the leading cause of... more Background: Breast cancer is the most common cancer in women in the U.S. and the leading cause of cancer related death among U.S. Latinas. Despite having lower breast cancer incidence, U.S. Latinas are more likely to be diagnosed with advanced stage disease compared to non-Hispanic White (NHW) women. This can be attributed to lower rates of screening and longer time to follow up after an abnormal mammogram in the former group. We developed a comprehensive promotores-led education and risk stratification program for Spanish-speaking Latinas to increase mammography screening, genetic testing, and the understanding of the impact of family history on cancer risk. Due to COVID-19 we adapted the program to a virtual platform. This study aimed to record and share the experience from the promotores' perspective as they educated the Latino(x) community through virtual sessions. Methods: We used a stakeholder continuous engagement approach and the construct of relational culture to build ...
Kennesaw Journal of Undergraduate Research, 2016
The focus of my research centers on the contemporary work of Georgia-based artist, Kara Elizabeth... more The focus of my research centers on the contemporary work of Georgia-based artist, Kara Elizabeth Walker. In conducting extensive research on the life of the artist as well as three select artworks which recall the antebellum slave era within the south, I argue the explicit presence of the power of the enslaved prepubescent girl and young woman. The three select works that I intend to analyze are Burn, a cut-paper silhouette on canvas created in 1998, The Invisible Beauty, a mixed media piece made in 2001, and Cut, a paper cut-out silhouette made in 1998. In a time where one’s power and freedom were both stripped away upon entering the prison-like confines of a plantation home, the life of a slave (a female slave in this case) was committed to grueling housework, the rearing of her slave master’s children in the place of her own, sexual exploitation and merciless beatings, humiliation, submission to her white counterparts, and in many cases, the occasion of rape. Walker’s intense, o...
Revista de Nutrición Clínica y Metabolismo, 2020
Global Journal of Health Science, Jul 11, 2018
Introduction: In Latin America the nutritional deficit is the most common problem affecting child... more Introduction: In Latin America the nutritional deficit is the most common problem affecting children under 5 years old, which is not an strange issue to Cartagena' s population, this type of phenomenon is due to lack of nutritional education or food security that leads to appearance of infectious diseases such as pneumonia becoming a public health problem. Objective: To correlate the clinical features of children with malnutrition, pneumonia and malnutrition, and pneumonia from Cartagena de Indias. 2010 to 2012. Methodology: Retrospective cross-sectional descriptive-correlational study. 220 medical records from three groups were analyzed, including 98 children with malnutrition, 100 children with pneumonia and 22 children with malnutrition and pneumonia simultaneously medically attended during 2012-2014. Logistic regression was performed applying Pearson and Durbin Watson calculations with the software SPSS 20.0 ®. Results: Male children have a higher prevalence of malnutrition and pneumonia simultaneously and separately by 63%. The age with more pneumonia and malnutrition cases is in children under 2 years old from stratum I, likewise weight and respiratory problems correlate as common clinical features. Conclusion: It is corroborated the existence of possible signs and symptoms common to pneumonia and malnutrition, in addition the design of dynamic programs that keep into account the environmental conditions.
El proposito de la Direccion de Extension es determinar los metodos conducentes a la prestacion d... more El proposito de la Direccion de Extension es determinar los metodos conducentes a la prestacion de un mejor servicio de las actividades de extension por parte de las unidades academicas y administrativas de la UIS, ademas de lograr la integracion y busqueda de soluciones conjuntas entre sus dependencias, con miras a la consolidacion y credibilidad de la Universidad industrial de Santander como una institucion que vela e incentiva el progreso en su region y en el pais. Para sentar las bases conceptuales que pudieran orientar la funcion de extension en la Universidad Industrial de Santander, se abordo la teoria moderna de las organizaciones empresariales, la cual ofrece un nuevo enfoque, una forma integral de visualizar la gerencia: El pensamiento sistemico. El enfoque del pensamiento sistemico es la actitud del ser humano, que se basa en la percepcion del mundo real en terminos de totalidades para su analisis, comprension y accionar. Como siguiente etapa, se realizo un diagnostico situacional de las actividades de extension llevadas a cabo por la Facultad de Ingenierias Fisicomecanicas durante el periodo 2003-primer semestre de 2004, por medio de un conjunto de instrumentos de analisis y recopilacion de informacion que permitieron el proceso de evaluacion, seguimiento y control de las actividades de extension en las distintas unidades academico-administrativas. En segunda instancia, se desarrollo un analisis interno y externo para la Facultad, utilizando algunas herramientas claves como ?el Analisis Estructural y la Matriz DOFA?, cuya finalidad era la identificacion de elementos importantes para fijar estrategias de orden social y de obtencion de recursos. Posteriormente se hizo el analisis y evaluacion de la forma como se esta llevando a cabo la funcion de Extension; definiendo un direccionamiento estrategico que conlleve a una eficacia y efectividad en su accionar; permitiendo una interaccion con la comunidad y actores sociales, derivada de una solidez institucional, investigativa y financiera que permitan el desarrollo local, regional y nacional. En razon a lo anterior, y acorde con el enfoque sistemico necesario para la concepcion de este proyecto, se empleo la estructura basica del Balance Scorecard o Cuadro de Mando Integral (CMI); el CMI permitio alinear las iniciativas y esfuerzos individuales hacia el logro de los objetivos estrategicos, encontrando relaciones de causalidad entre los mismos y las estrategias que se desprenden de ellos, sirviendo como punto de partida para implementar cambios conducentes a una mayor eficiencia en los servicios ofrecidos por las unidades academico- administrativas de la Facultad.
Serie Bibliotecologia Y Gestion De Informacion, Apr 17, 2012
Se establecen las diferencias entre RDA y las AACR2 y el grado de conocimiento y aceptación de la... more Se establecen las diferencias entre RDA y las AACR2 y el grado de conocimiento y aceptación de las RDA en Chile. Se identifican los recursos que utilizan las bibliotecas universitarias para la descripción documental, en especial de los recursos electrónicos y se establece el perfil profesional para la implementación de las RDA.
Broiler production has undergone major developments in recent years and is widespread in our coun... more Broiler production has undergone major developments in recent years and is widespread in our country, especially in temperate climates, due to its high yield and high consumption. The aim of this study was to characterize the production system and health management in three farms in the department of Cundinamarca. The work was developed in three poultry broiler farms located in the municipalities of the Nile, Fusagasugá and Arbelaez. Program of cleaning and disinfection, pest control, solid and liquid waste, food and health plans: data formats established by the variables related to production and biosecurity, such as collected. Two levels of modernization were found in production systems in the three farms. Biosecurity parameters were determined following the guidelines of good farming practices, the temperature was found as a determinant factor in weight gain and stability of the house. Additionally, no differences in the facilities of the sheds were found and they ensure that all...
Metabolic Syndrome and Related Disorders, 2007
The purpose of this study was to examine effect modifiers of the relationship between family hist... more The purpose of this study was to examine effect modifiers of the relationship between family history of diabetes, a proxy for genetic predisposition, and the metabolic syndrome. Subjects were a cross-sectional sample of 205 Mexican-Americans patients of the San Ysidro Health Center in San Diego County. Self-reported parental history of diabetes was examined as a risk factor for individual metabolic syndrome traits (hyperglycemia, hypertension, abdominal obesity, hypertriglyceridemia and low HDL-cholesterol) and a composite phenotype, defined both by standard modified National Cholesterol Education Program- Adult Treatment Panel III (NCEP-ATPIII) criteria and using principal components analysis, in age and sex-adjusted multiple logistic and linear regression models. Family history of diabetes was most strongly associated with individual traits of hyperglycemia (P = .0002) and low HDL-C (P = .001) and conferred a significant increased odds of metabolic syndrome defined by both NCEP-ATPIII criteria (odds ratio 3.57, 95% confidence interval 1.82, 7.01; P = .0002) and by principal components analysis (P = 0.003). Moreover, the family history association with metabolic syndrome was modified by number of years living in the United States (interaction P = .04). This same effect was not seen for diabetes (P = .19). The results of our study support a common etiology for at least some components of the metabolic syndrome, especially hyperglycemia and low HDL-cholesterol, the basis of which may be genetic. Moreover, the effect of genes on these traits may be modified by longer duration in the United States, supporting the concept of gene-environment interaction in the development of the metabolic syndrome.
Proceedings of the 5th international workshop on Software and performance - WOSP '05, 2005
Page 1. Applying SPE Techniques for Modeling a Grid-enabled JAVA Platform Mariela Curiel Computer... more Page 1. Applying SPE Techniques for Modeling a Grid-enabled JAVA Platform Mariela Curiel Computer Science Department Simón Bolıvar University Caracas, Venezuela mcuriel@ldc.usb.ve M. Angélica Pérez Information ...
Revista chilena de pediatría, 2001
La fibrosis quística (FQ) es una enfermedad hereditaria letal, que se transmite de manera autosóm... more La fibrosis quística (FQ) es una enfermedad hereditaria letal, que se transmite de manera autosómica recesiva. Es más frecuente en los grupos de origen caucásico, alcanzando incidencias entre 1 en 2 500 a 1 en 4 000 RN vivos, según la constitución étnica de cada país 1, 2 . En ...
Solid State Communications, 2003
The mixed-compound of Sr 12x Ca x TiO 3 has shown several compositional phase transformations. Ph... more The mixed-compound of Sr 12x Ca x TiO 3 has shown several compositional phase transformations. Photoluminescence and excitation spectra of the samples with different x and doped with 0.2% Pr 3þ were investigated. Changes in the emission spectra were observed in different phases. The blue emission at 491 nm from 3 P 0 state was found quite strong in the tetragonal phase, and was thermally quenched in the orthorhombic phases. The intensity of the red luminescence from 1 D 2 increases with increasing content of calcium. The strongest red emission is obtained from CaTiO 3 :Pr 3þ. The results are discussed based on the configuration coordinate model and interaction of Pr with the charge transfer exciton state of the Ti complex.
Journal of Neuroimaging, 2006
Background. Abnormalities in diffusion-weighted (DWI) and perfusion-weighted (PWI) magnetic reson... more Background. Abnormalities in diffusion-weighted (DWI) and perfusion-weighted (PWI) magnetic resonance imaging (MRI) are thought to reflect the presence of brain tissue at risk for ischemic stroke. Many patients with acute ischemic stroke have a mismatch pattern in which the PWI volume is larger than the DWI lesion. This mismatch typically resolves over 24-48 hours. Little is known about the presence of DWI-PWI mismatch in later stages of stroke. Methods. This is a retrospective study of 122 patients admitted with a diagnosis of acute ischemic stroke who had DWI and PWI abnormalities on studies performed within 7 days of onset of symptoms. Patients were divided into two groups: those with MRI performed <48 hours and those with MRI performed ≥48 hours from onset of symptoms. Results. Among 42 patients with MRI performed ≥48 hours after onset of stroke symptoms, 15 of 42 (36%) showed a mismatch pattern, compared to 45 of 80 (56%) in the <48 hours group (P < 0.05). Most of the patients in the ≥48 hours group with mismatch had large artery occlusive disease and many had neurological fluctuations. A subset of these patients were treated with induced hypertension and showed clinical improvement. Conclusions. Some patients have persistent DWI-PWI mismatch up to several days after stroke onset. Further studies are
Experimental Cell Research, 2010
Exosome vesicles of endocytic origin are involved in communication between tumor and immune cells... more Exosome vesicles of endocytic origin are involved in communication between tumor and immune cells. In addition, membrane rafts (MR) may support the sorting of proteins associated with exosomes. CD38 is found at the plasma membrane and in recycling endosomes, which are both redistributed toward the immunological synapse (IS) upon T cell antigen receptor (TCR) engagement. The data of this study provide evidence that CD38 is expressed on the surface of secreted exosomes derived from lymphoblastoid B cells. Exosomic CD38 is associated with the signaling molecules CD81, Hsc-70 and Lyn. Likewise, in MR, CD38 is associated with CD81, CD19, Lyn, Gαi-2, Hsc-70 and actin. Therefore, a high degree of overlap in the pattern of signaling proteins associated with CD38 in exosomes and MR exists. Exosomic and MR CD38, by virtue of these interactions, have signaling potential. Indeed, CD38 is enzymatically active in both exosomes and MR, and CD38 ligation induces Akt/PKB and Erk activation, which is accompanied by increased translocation of CD38 into MR. In conclusion, the present study indicates that CD38 localizes to MR, where it promotes cell signaling, and it is exported out of the cells through the exosome-mediated exocytic pathway, where it may act as an intercellular messenger.
e-Polymers, 2014
Scanning electron microscopy (SEM) is employed to monitor the surface morphology of polypyrrole f... more Scanning electron microscopy (SEM) is employed to monitor the surface morphology of polypyrrole films (PPy) grown on different working electrodes (i.e., vitreous carbon and Au (111)) under diverse experimental conditions (i.e., dynamic vs. static potential protocols) and anion dopants (i.e., I- and F-). The morphology of the electrosynthesized films includes rings (doughnuts) and microcontainers, and depends on the synthesis parameters such as the electropolymerization method, the nature of the substrate, the anion dopant, and the sequence of sandwich composite growth. The formation of well-defined rings and microcontainers is attributed to overoxidation occurring during the formation of F--doped PPy. It is possible to design microcontainers by controlling the overoxidation and degradation of the polymer surface.
Rev. Fac. Ing. UCV, 2010
... María Angélica Pérez 1 , Rosa Pérez 2 , Susan León 2 , María Maninat 2 , José Triana 2. 1 Uni... more ... María Angélica Pérez 1 , Rosa Pérez 2 , Susan León 2 , María Maninat 2 , José Triana 2. 1 Universidad Simón Bolívar. Departamento Procesos y Sistemas. Laboratorio de Investigación en Sistemas de Información LISI. Edo. Miranda. Venezuela. ...
Biophysical Journal, 2011
Background: Cardiac arrhythmias are particularly common in heart failure patients. The slow delay... more Background: Cardiac arrhythmias are particularly common in heart failure patients. The slow delayed rectifier Kþ current (IKs) is decreased in patients and in animal models of heart failure. However, the molecular mechanisms for IKs decrease are not known. PKC signaling is one of the most prominent pathways activated during heart failure, with both expression and activation of PKC being increased. Hypothesis: Chronic PKC activation inhibits IKs and delays cardiac repolarization, contributing to arrhythmogenic risk in heart failure. Methods: Human IKs channels, PKCalpha catalytic subunit (CA) and alpha1A-adrenoceptor (alpha1A-AR) were expressed in HEK293T cells. IKs current was measured by patch clamp. Subcellular localization of GFP-tagged IKs channels was observed by confocal microscopy. Results: IKs currents were strongly inhibited by either overexpression of PKCalphaCA or 2-hr alpha1A-AR stimulation by phenylephirne (Fig. 1A), although acute application of Ca2þ-dependent PKC (cPKC) activator peptide or alpha1A-AR stimulation increased IKs. Plasma membrane localization of GFP-tagged IKs channels was significantly decreased by chronic alpha1A-AR-cPKC signaling activation (Fig.1B). Application of PKC inhibitors or mutation of a putative PKC phosphorylation site in the auxiliary KCNE1 subunit abolished this effect. Conclusion: Chronic PKC activation inhibits IKs currents by decreasing channel plasma membrane expression via direct phosphorylation of KCNE1 subunit. Our results suggest that cPKC-dependent phosphorylation of the IKs channel may contribute to QT prolongation and arrhythmogenesis in heart failure and implicate cPKC inhibitors as potential novel antiarrhythmic drugs.
Contemporary Clinical Trials Communications
Cancer Epidemiology, Biomarkers & Prevention, 2022
Background: Breast cancer is the most common cancer in women in the U.S. and the leading cause of... more Background: Breast cancer is the most common cancer in women in the U.S. and the leading cause of cancer related death among U.S. Latinas. Despite having lower breast cancer incidence, U.S. Latinas are more likely to be diagnosed with advanced stage disease compared to non-Hispanic White (NHW) women. This can be attributed to lower rates of screening and longer time to follow up after an abnormal mammogram in the former group. We developed a comprehensive promotores-led education and risk stratification program for Spanish-speaking Latinas to increase mammography screening, genetic testing, and the understanding of the impact of family history on cancer risk. Due to COVID-19 we adapted the program to a virtual platform. This study aimed to record and share the experience from the promotores' perspective as they educated the Latino(x) community through virtual sessions. Methods: We used a stakeholder continuous engagement approach and the construct of relational culture to build ...
Kennesaw Journal of Undergraduate Research, 2016
The focus of my research centers on the contemporary work of Georgia-based artist, Kara Elizabeth... more The focus of my research centers on the contemporary work of Georgia-based artist, Kara Elizabeth Walker. In conducting extensive research on the life of the artist as well as three select artworks which recall the antebellum slave era within the south, I argue the explicit presence of the power of the enslaved prepubescent girl and young woman. The three select works that I intend to analyze are Burn, a cut-paper silhouette on canvas created in 1998, The Invisible Beauty, a mixed media piece made in 2001, and Cut, a paper cut-out silhouette made in 1998. In a time where one’s power and freedom were both stripped away upon entering the prison-like confines of a plantation home, the life of a slave (a female slave in this case) was committed to grueling housework, the rearing of her slave master’s children in the place of her own, sexual exploitation and merciless beatings, humiliation, submission to her white counterparts, and in many cases, the occasion of rape. Walker’s intense, o...
Revista de Nutrición Clínica y Metabolismo, 2020
Global Journal of Health Science, Jul 11, 2018
Introduction: In Latin America the nutritional deficit is the most common problem affecting child... more Introduction: In Latin America the nutritional deficit is the most common problem affecting children under 5 years old, which is not an strange issue to Cartagena' s population, this type of phenomenon is due to lack of nutritional education or food security that leads to appearance of infectious diseases such as pneumonia becoming a public health problem. Objective: To correlate the clinical features of children with malnutrition, pneumonia and malnutrition, and pneumonia from Cartagena de Indias. 2010 to 2012. Methodology: Retrospective cross-sectional descriptive-correlational study. 220 medical records from three groups were analyzed, including 98 children with malnutrition, 100 children with pneumonia and 22 children with malnutrition and pneumonia simultaneously medically attended during 2012-2014. Logistic regression was performed applying Pearson and Durbin Watson calculations with the software SPSS 20.0 ®. Results: Male children have a higher prevalence of malnutrition and pneumonia simultaneously and separately by 63%. The age with more pneumonia and malnutrition cases is in children under 2 years old from stratum I, likewise weight and respiratory problems correlate as common clinical features. Conclusion: It is corroborated the existence of possible signs and symptoms common to pneumonia and malnutrition, in addition the design of dynamic programs that keep into account the environmental conditions.
El proposito de la Direccion de Extension es determinar los metodos conducentes a la prestacion d... more El proposito de la Direccion de Extension es determinar los metodos conducentes a la prestacion de un mejor servicio de las actividades de extension por parte de las unidades academicas y administrativas de la UIS, ademas de lograr la integracion y busqueda de soluciones conjuntas entre sus dependencias, con miras a la consolidacion y credibilidad de la Universidad industrial de Santander como una institucion que vela e incentiva el progreso en su region y en el pais. Para sentar las bases conceptuales que pudieran orientar la funcion de extension en la Universidad Industrial de Santander, se abordo la teoria moderna de las organizaciones empresariales, la cual ofrece un nuevo enfoque, una forma integral de visualizar la gerencia: El pensamiento sistemico. El enfoque del pensamiento sistemico es la actitud del ser humano, que se basa en la percepcion del mundo real en terminos de totalidades para su analisis, comprension y accionar. Como siguiente etapa, se realizo un diagnostico situacional de las actividades de extension llevadas a cabo por la Facultad de Ingenierias Fisicomecanicas durante el periodo 2003-primer semestre de 2004, por medio de un conjunto de instrumentos de analisis y recopilacion de informacion que permitieron el proceso de evaluacion, seguimiento y control de las actividades de extension en las distintas unidades academico-administrativas. En segunda instancia, se desarrollo un analisis interno y externo para la Facultad, utilizando algunas herramientas claves como ?el Analisis Estructural y la Matriz DOFA?, cuya finalidad era la identificacion de elementos importantes para fijar estrategias de orden social y de obtencion de recursos. Posteriormente se hizo el analisis y evaluacion de la forma como se esta llevando a cabo la funcion de Extension; definiendo un direccionamiento estrategico que conlleve a una eficacia y efectividad en su accionar; permitiendo una interaccion con la comunidad y actores sociales, derivada de una solidez institucional, investigativa y financiera que permitan el desarrollo local, regional y nacional. En razon a lo anterior, y acorde con el enfoque sistemico necesario para la concepcion de este proyecto, se empleo la estructura basica del Balance Scorecard o Cuadro de Mando Integral (CMI); el CMI permitio alinear las iniciativas y esfuerzos individuales hacia el logro de los objetivos estrategicos, encontrando relaciones de causalidad entre los mismos y las estrategias que se desprenden de ellos, sirviendo como punto de partida para implementar cambios conducentes a una mayor eficiencia en los servicios ofrecidos por las unidades academico- administrativas de la Facultad.
Serie Bibliotecologia Y Gestion De Informacion, Apr 17, 2012
Se establecen las diferencias entre RDA y las AACR2 y el grado de conocimiento y aceptación de la... more Se establecen las diferencias entre RDA y las AACR2 y el grado de conocimiento y aceptación de las RDA en Chile. Se identifican los recursos que utilizan las bibliotecas universitarias para la descripción documental, en especial de los recursos electrónicos y se establece el perfil profesional para la implementación de las RDA.
Broiler production has undergone major developments in recent years and is widespread in our coun... more Broiler production has undergone major developments in recent years and is widespread in our country, especially in temperate climates, due to its high yield and high consumption. The aim of this study was to characterize the production system and health management in three farms in the department of Cundinamarca. The work was developed in three poultry broiler farms located in the municipalities of the Nile, Fusagasugá and Arbelaez. Program of cleaning and disinfection, pest control, solid and liquid waste, food and health plans: data formats established by the variables related to production and biosecurity, such as collected. Two levels of modernization were found in production systems in the three farms. Biosecurity parameters were determined following the guidelines of good farming practices, the temperature was found as a determinant factor in weight gain and stability of the house. Additionally, no differences in the facilities of the sheds were found and they ensure that all...
Metabolic Syndrome and Related Disorders, 2007
The purpose of this study was to examine effect modifiers of the relationship between family hist... more The purpose of this study was to examine effect modifiers of the relationship between family history of diabetes, a proxy for genetic predisposition, and the metabolic syndrome. Subjects were a cross-sectional sample of 205 Mexican-Americans patients of the San Ysidro Health Center in San Diego County. Self-reported parental history of diabetes was examined as a risk factor for individual metabolic syndrome traits (hyperglycemia, hypertension, abdominal obesity, hypertriglyceridemia and low HDL-cholesterol) and a composite phenotype, defined both by standard modified National Cholesterol Education Program- Adult Treatment Panel III (NCEP-ATPIII) criteria and using principal components analysis, in age and sex-adjusted multiple logistic and linear regression models. Family history of diabetes was most strongly associated with individual traits of hyperglycemia (P = .0002) and low HDL-C (P = .001) and conferred a significant increased odds of metabolic syndrome defined by both NCEP-ATPIII criteria (odds ratio 3.57, 95% confidence interval 1.82, 7.01; P = .0002) and by principal components analysis (P = 0.003). Moreover, the family history association with metabolic syndrome was modified by number of years living in the United States (interaction P = .04). This same effect was not seen for diabetes (P = .19). The results of our study support a common etiology for at least some components of the metabolic syndrome, especially hyperglycemia and low HDL-cholesterol, the basis of which may be genetic. Moreover, the effect of genes on these traits may be modified by longer duration in the United States, supporting the concept of gene-environment interaction in the development of the metabolic syndrome.
Proceedings of the 5th international workshop on Software and performance - WOSP '05, 2005
Page 1. Applying SPE Techniques for Modeling a Grid-enabled JAVA Platform Mariela Curiel Computer... more Page 1. Applying SPE Techniques for Modeling a Grid-enabled JAVA Platform Mariela Curiel Computer Science Department Simón Bolıvar University Caracas, Venezuela mcuriel@ldc.usb.ve M. Angélica Pérez Information ...
Revista chilena de pediatría, 2001
La fibrosis quística (FQ) es una enfermedad hereditaria letal, que se transmite de manera autosóm... more La fibrosis quística (FQ) es una enfermedad hereditaria letal, que se transmite de manera autosómica recesiva. Es más frecuente en los grupos de origen caucásico, alcanzando incidencias entre 1 en 2 500 a 1 en 4 000 RN vivos, según la constitución étnica de cada país 1, 2 . En ...
Solid State Communications, 2003
The mixed-compound of Sr 12x Ca x TiO 3 has shown several compositional phase transformations. Ph... more The mixed-compound of Sr 12x Ca x TiO 3 has shown several compositional phase transformations. Photoluminescence and excitation spectra of the samples with different x and doped with 0.2% Pr 3þ were investigated. Changes in the emission spectra were observed in different phases. The blue emission at 491 nm from 3 P 0 state was found quite strong in the tetragonal phase, and was thermally quenched in the orthorhombic phases. The intensity of the red luminescence from 1 D 2 increases with increasing content of calcium. The strongest red emission is obtained from CaTiO 3 :Pr 3þ. The results are discussed based on the configuration coordinate model and interaction of Pr with the charge transfer exciton state of the Ti complex.
Journal of Neuroimaging, 2006
Background. Abnormalities in diffusion-weighted (DWI) and perfusion-weighted (PWI) magnetic reson... more Background. Abnormalities in diffusion-weighted (DWI) and perfusion-weighted (PWI) magnetic resonance imaging (MRI) are thought to reflect the presence of brain tissue at risk for ischemic stroke. Many patients with acute ischemic stroke have a mismatch pattern in which the PWI volume is larger than the DWI lesion. This mismatch typically resolves over 24-48 hours. Little is known about the presence of DWI-PWI mismatch in later stages of stroke. Methods. This is a retrospective study of 122 patients admitted with a diagnosis of acute ischemic stroke who had DWI and PWI abnormalities on studies performed within 7 days of onset of symptoms. Patients were divided into two groups: those with MRI performed <48 hours and those with MRI performed ≥48 hours from onset of symptoms. Results. Among 42 patients with MRI performed ≥48 hours after onset of stroke symptoms, 15 of 42 (36%) showed a mismatch pattern, compared to 45 of 80 (56%) in the <48 hours group (P < 0.05). Most of the patients in the ≥48 hours group with mismatch had large artery occlusive disease and many had neurological fluctuations. A subset of these patients were treated with induced hypertension and showed clinical improvement. Conclusions. Some patients have persistent DWI-PWI mismatch up to several days after stroke onset. Further studies are
Experimental Cell Research, 2010
Exosome vesicles of endocytic origin are involved in communication between tumor and immune cells... more Exosome vesicles of endocytic origin are involved in communication between tumor and immune cells. In addition, membrane rafts (MR) may support the sorting of proteins associated with exosomes. CD38 is found at the plasma membrane and in recycling endosomes, which are both redistributed toward the immunological synapse (IS) upon T cell antigen receptor (TCR) engagement. The data of this study provide evidence that CD38 is expressed on the surface of secreted exosomes derived from lymphoblastoid B cells. Exosomic CD38 is associated with the signaling molecules CD81, Hsc-70 and Lyn. Likewise, in MR, CD38 is associated with CD81, CD19, Lyn, Gαi-2, Hsc-70 and actin. Therefore, a high degree of overlap in the pattern of signaling proteins associated with CD38 in exosomes and MR exists. Exosomic and MR CD38, by virtue of these interactions, have signaling potential. Indeed, CD38 is enzymatically active in both exosomes and MR, and CD38 ligation induces Akt/PKB and Erk activation, which is accompanied by increased translocation of CD38 into MR. In conclusion, the present study indicates that CD38 localizes to MR, where it promotes cell signaling, and it is exported out of the cells through the exosome-mediated exocytic pathway, where it may act as an intercellular messenger.
e-Polymers, 2014
Scanning electron microscopy (SEM) is employed to monitor the surface morphology of polypyrrole f... more Scanning electron microscopy (SEM) is employed to monitor the surface morphology of polypyrrole films (PPy) grown on different working electrodes (i.e., vitreous carbon and Au (111)) under diverse experimental conditions (i.e., dynamic vs. static potential protocols) and anion dopants (i.e., I- and F-). The morphology of the electrosynthesized films includes rings (doughnuts) and microcontainers, and depends on the synthesis parameters such as the electropolymerization method, the nature of the substrate, the anion dopant, and the sequence of sandwich composite growth. The formation of well-defined rings and microcontainers is attributed to overoxidation occurring during the formation of F--doped PPy. It is possible to design microcontainers by controlling the overoxidation and degradation of the polymer surface.
Rev. Fac. Ing. UCV, 2010
... María Angélica Pérez 1 , Rosa Pérez 2 , Susan León 2 , María Maninat 2 , José Triana 2. 1 Uni... more ... María Angélica Pérez 1 , Rosa Pérez 2 , Susan León 2 , María Maninat 2 , José Triana 2. 1 Universidad Simón Bolívar. Departamento Procesos y Sistemas. Laboratorio de Investigación en Sistemas de Información LISI. Edo. Miranda. Venezuela. ...
Biophysical Journal, 2011
Background: Cardiac arrhythmias are particularly common in heart failure patients. The slow delay... more Background: Cardiac arrhythmias are particularly common in heart failure patients. The slow delayed rectifier Kþ current (IKs) is decreased in patients and in animal models of heart failure. However, the molecular mechanisms for IKs decrease are not known. PKC signaling is one of the most prominent pathways activated during heart failure, with both expression and activation of PKC being increased. Hypothesis: Chronic PKC activation inhibits IKs and delays cardiac repolarization, contributing to arrhythmogenic risk in heart failure. Methods: Human IKs channels, PKCalpha catalytic subunit (CA) and alpha1A-adrenoceptor (alpha1A-AR) were expressed in HEK293T cells. IKs current was measured by patch clamp. Subcellular localization of GFP-tagged IKs channels was observed by confocal microscopy. Results: IKs currents were strongly inhibited by either overexpression of PKCalphaCA or 2-hr alpha1A-AR stimulation by phenylephirne (Fig. 1A), although acute application of Ca2þ-dependent PKC (cPKC) activator peptide or alpha1A-AR stimulation increased IKs. Plasma membrane localization of GFP-tagged IKs channels was significantly decreased by chronic alpha1A-AR-cPKC signaling activation (Fig.1B). Application of PKC inhibitors or mutation of a putative PKC phosphorylation site in the auxiliary KCNE1 subunit abolished this effect. Conclusion: Chronic PKC activation inhibits IKs currents by decreasing channel plasma membrane expression via direct phosphorylation of KCNE1 subunit. Our results suggest that cPKC-dependent phosphorylation of the IKs channel may contribute to QT prolongation and arrhythmogenesis in heart failure and implicate cPKC inhibitors as potential novel antiarrhythmic drugs.