1,069 research outputs found
Development of a background electrolyte for the determination of inorganic cations in high ionic strength samples by capillary electrophoresis with indirect UV-absorption detection
In this study, a background electrolyte capable to separate and quantify inorganic cations in high ionic strength samples by UV-absorption indirect detection was designed. In this regard, the four most abundant monovalent and divalent cations in earth crust (K+ , Na+ , Ca+2, Mg+2) were selected as model compounds. A group of small carboxylic acids and, several toluidines and pyridines were evaluated as mild strength complexing agents and chromophoric probes, respectively. The optimized background electrolyte was composed of 200 mM 2,4,6-trimethylpyridine as the chromophoric probe, 250 mM lactic acid as the weak complexing agent and pH buffering reagent (adjusted to pH 4.5), and 5 % v/v methanol as organic solvent modifier. Based on a minimum number of components, it provided outstanding separation performance in less than 4 min in a wide linear dynamic range (10 - 2500 µg∙mL-1 ). Performances were contrasted against a reference method based on conductometric detection. Furthermore, studies of separation efficiency and peak shape were carried out at different analyte concentrations in high electric conductivity solutions. The herein developed method demonstrated exceptional features in terms of limits of detection (~10 µg∙mL-1 ), resolution, speed of analysis, sensitivity and peak capacity in high electric conductivity samples. Moreover, the method was successfully applied to high ionic strength samples such as rock digest, sea water, soy sauce and isotonic drinks.Fil: Lancioni, Carlina. Universidad Nacional de la Plata. Facultad de Cs.exactas. Laboratorio de Investigacion y Desarrollo de Metodos Analiticos. - Comision de Investigaciones Cientificas de la Provincia de Buenos Aires. Laboratorio de Investigacion y Desarrollo de Metodos Analiticos.; Argentina. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Centro CientÃfico Tecnológico Conicet - La Plata; ArgentinaFil: Aspromonte, Juan. Universidad Nacional de la Plata. Facultad de Cs.exactas. Laboratorio de Investigacion y Desarrollo de Metodos Analiticos. - Comision de Investigaciones Cientificas de la Provincia de Buenos Aires. Laboratorio de Investigacion y Desarrollo de Metodos Analiticos.; Argentina. Katholikie Universiteit Leuven; Bélgica. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Centro CientÃfico Tecnológico Conicet - La Plata; ArgentinaFil: Tascon, Marcos. Universidad Nacional de San MartÃn. Instituto de Investigación e IngenierÃa Ambiental. - Consejo Nacional de Investigaciones CientÃficas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigación e IngenierÃa Ambiental; ArgentinaFil: Gagliardi, Leonardo Gabriel. Universidad Nacional de la Plata. Facultad de Cs.exactas. Laboratorio de Investigacion y Desarrollo de Metodos Analiticos. - Comision de Investigaciones Cientificas de la Provincia de Buenos Aires. Laboratorio de Investigacion y Desarrollo de Metodos Analiticos.; Argentina. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Centro CientÃfico Tecnológico Conicet - La Plata; Argentin
A new scoring system to stratify risk in unstable angina
BACKGROUND: We performed this study to develop a new scoring system to stratify different levels of risk in patients admitted to hospital with a diagnosis of unstable angina (UA), which is a complex syndrome that encompasses different outcomes. Many prognostic variables have been described but few efforts have been made to group them in order to enhance their individual predictive power. METHODS: In a first phase, 473 patients were prospectively analyzed to determine which factors were significantly associated with the in-hospital occurrence of refractory ischemia, acute myocardial infarction (AMI) or death. A risk score ranging from 0 to 10 points was developed using a multivariate analysis. In a second phase, such score was validated in a new sample of 242 patients and it was finally applied to the entire population (n = 715). RESULTS: ST-segment deviation on the electrocardiogram, age ≥ 70 years, previous bypass surgery and troponin T ≥ 0.1 ng/mL were found as independent prognostic variables. A clear distinction was shown among categories of low, intermediate and high risk, defined according to the risk score. The incidence of the triple end-point was 6 %, 19.2 % and 44.7 % respectively, and the figures for AMI or death were 2 %, 11.4 % and 27.6 % respectively (p < 0.001). CONCLUSIONS: This new scoring system is simple and easy to achieve. It allows a very good stratification of risk in patients having a clinical diagnosis of UA. They may be divided in three categories, which could be of help in the decision-making process
Genome-Wide DNA Methylation Analysis Identifies Novel Hypomethylated Non-Pericentromeric Genes with Potential Clinical Implications in ICF Syndrome
Introduction and Results Immunodeficiency, centromeric instability and facial anomalies syndrome (ICF) is a rare autosomal recessive disease, characterized by severe hypomethylation in pericentromeric regions of chromosomes (1, 16 and 9), marked immunodeficiency and facial anomalies. The majority of ICF patients present mutations in the DNMT3B gene, affecting the DNA methyltransferase activity of the protein. In the present study, we have used the Infinium 450K DNA methylation array to evaluate the methylation level of 450,000 CpGs in lymphoblastoid cell lines and untrasformed fibroblasts derived from ICF patients and healthy donors. Our results demonstrate that ICF-specific DNMT3B variants A603T/STP807ins and V699G/R54X cause global DNA hypomethylation compared to wild-type protein. We identified 181 novel differentially methylated positions (DMPs) including subtelomeric and intrachromosomic regions, outside the classical ICF-related pericentromeric hypomethylated positions. Interestingly, these sites were mainly located in intergenic regions and inside the CpG islands. Among the identified hypomethylated CpG-island associated genes, we confirmed the overexpression of three selected genes, BOLL, SYCP2 and NCRNA00221, in ICF compared to healthy controls, which are supposed to be expressed in germ line and silenced in somatic tissues. Conclusions In conclusion, this study contributes in clarifying the direct relationship between DNA methylation defect and gene expression impairment in ICF syndrome, identifying novel direct target genes of DNMT3B. A high percentage of the DMPs are located in the subtelomeric regions, indicating a specific role of DNMT3B in methylating these chromosomal sites. Therefore, we provide further evidence that hypomethylation in specific non-pericentromeric regions of chromosomes might be involved in the molecular pathogenesis of ICF syndrome. The detection of DNA hypomethylation at BOLL, SYCP2 and NCRNA00221 may pave the way for the development of specific clinical biomarkers with the aim to facilitate the identification of ICF patients
Avances en propuestas heurÃsticas para consultas a R-Tree
En la actualidad las bases de datos espaciales han tomado gran interés dado la cantidad de aplicaciones en las que son utilizadas, esto ha generado una mayor necesidad en investigar métodos que mejoren el desempeño en la resolución de consultas de tipo espacial.
Los trabajos de investigación en Bases de Datos espaciales se han centralizado en el modelado y la resolución de consultas, basándose en la geometrÃa asociada a los objetos almacenados en una base de datos[1]. Nuestro trabajo de investigación se abocará a poder resolver eficientemente consultas a Ãndices R-tree’s, considerando atributos derivados de la geometrÃa de los objetos espaciales como lo son por ejemplo el área en el caso de los polÃgonos o la longitud en las poligonales.
Nuestro interés radica en este tipo de Ãndices R-Tree’s debido a que es un método de acceso estándar para las bases de datos espaciales, elegido por la mayorÃa de los Sistemas de Administración de Bases de Datos.Eje: IngenierÃa de Software y Base de DatosRed de Universidades con Carreras en Informática (RedUNCI
I+3 R-Tree: un método de acceso espacio-temporal
Este artÃculo presenta una estructura de indexación de datos espacio-temporales para objetos que se mueven en una región fija a lo largo del tiempo. Este método de acceso permite procesar consultas que contemplen relaciones espacio-temporales, considerando el pasado y el presente. El método considera el procesamiento de cuatro tipos de consultas, a) timeslice, b) intervalo, c) evento y d) trayectoria. Mostramos resultados de la evaluación experimental que nos permitieron observar el comportamiento de esta estructura respecto de las consultas mencionadas.VI Workshop Bases de Datos y MinerÃa de Datos (WBD)Red de Universidades con Carreras en Informática (RedUNCI
Propuestas heurÃsticas para consultas a R-Tree
El avance tecnológico y la cantidad de apli-caciones surgidas en el campo de las bases de datos espaciales, provocaron que las in-vestigaciones en torno a la resolución de consultas de tipo espacial, se profundizaran a fin de mejorar el desempeño de las mis-mas.
En nuestro trabajo de investigación tenemos un área dedicada al estudio de propuestas para resolver eficientemente consultas a Ãndices R-tree’s, considerando atributos derivados de la geometrÃa de los objetos espaciales.
Nuestro especial interés en este tipo de Ãndi-ces se debe a que es un método de acceso estándar para las bases de datos espaciales, elegido por la mayorÃa de los Sistemas de Administración de Bases de Datos.Eje: IngenierÃa de software y base de datosRed de Universidades con Carreras en Informática (RedUNCI
Resultados experimentales sobre nuevas propuestas heurÃsticas para consultas a R-Tree
En este trabajo se presenta un algoritmo para procesar consultas cuyos predicados establecen restricciones sobre atributos derivados de la geometrÃa (área o perÃmetro) de los objetos. Nuestro algoritmo se basa en el método de acceso espacial R-Tree para evaluar las consultas y en las propiedades entre el MBR (Minimum Bounding Rectangle) y su área o perÃmetro de un objeto.
Nosotros realizamos una serie de experimentos que permitieron analizar el desempeño del algoritmo para procesar consultas con restricciones sobre el área de los objetos. Los experimentos muestran que el algoritmo tiene una buena capacidad de estimación de la respuesta de la consulta, ya que solamente sobreestima un 25.87% de los objetos que realmente cumplen con las propiedades de la consulta. Por lo tanto, ante la ausencia de un Ãndice para el atributo derivado, nuestro algoritmo es una alternativa competitiva para procesar este tipo de consultasIn this work an algorithm is presented to process consultations whose predicates establish restrictions on attributes derived from geometry (area or perimeter) of the objects. Our algorithm is based on the space access method R-Tree to evaluate the consultations and on the properties between MBR (Minimum Bounding Rectangle) and its area or perimeter of an object. We made a series of experiments that allowed to analyze the performance of the algorithm to process consultations with restrictions on the area of the objects. The experiments show that the algorithm has a good capacity of estimation of the answer of the consultation, since only overestimates 25,87% of the objects that really fulfill the properties of the consultation. Therefore, before the absence of an index for the derived attribute, our algorithm is a competitive alternative to process this type of consultationsIII Workshop de IngenierÃa de Software y Bases de Datos (WISBD)Red de Universidades con Carreras en Informática (RedUNCI
Avances en propuestas heurÃsticas para consultas a R-Tree
En la actualidad las bases de datos espaciales han tomado gran interés dado la cantidad de aplicaciones en las que son utilizadas, esto ha generado una mayor necesidad en investigar métodos que mejoren el desempeño en la resolución de consultas de tipo espacial.
Los trabajos de investigación en Bases de Datos espaciales se han centralizado en el modelado y la resolución de consultas, basándose en la geometrÃa asociada a los objetos almacenados en una base de datos[1]. Nuestro trabajo de investigación se abocará a poder resolver eficientemente consultas a Ãndices R-tree’s, considerando atributos derivados de la geometrÃa de los objetos espaciales como lo son por ejemplo el área en el caso de los polÃgonos o la longitud en las poligonales.
Nuestro interés radica en este tipo de Ãndices R-Tree’s debido a que es un método de acceso estándar para las bases de datos espaciales, elegido por la mayorÃa de los Sistemas de Administración de Bases de Datos.Eje: IngenierÃa de Software y Base de DatosRed de Universidades con Carreras en Informática (RedUNCI
Development of a background electrolyte for the determination of inorganic cations in high ionic strength samples by capillary electrophoresis with indirect UV-absorption detection
In this study, a background electrolyte capable to separate and quantify inorganic cations in high ionic strength samples by UV-absorption indirect detection was designed. In this regard, the four most abundant monovalent and divalent cations in earth crust (K+, Na+, Ca+2, Mg+2) were selected as model compounds. A group of small carboxylic acids and, several toluidines and pyridines were evaluated as mild strength complexing agents and chromophoric probes, respectively. The optimized background electrolyte was composed of 200 mM 2,4,6-trimethylpyridine as the chromophoric probe, 250 mM lactic acid as the weak complexing agent and pH buffering reagent (adjusted to pH 4.5), and 5% v/v methanol as organic solvent modifier. Based on a minimum number of components, it provided outstanding separation performance in less than 4 min in a wide linear dynamic range (10 - 2500 µg·mL−1). Performances were contrasted against a reference method based on conductometric detection. Furthermore, studies of separation efficiency and peak shape were carried out at different analyte concentrations in high electric conductivity solutions. The herein developed method demonstrated exceptional features in terms of limits of detection (~10 µg·mL−1), resolution, speed of analysis, sensitivity and peak capacity in high electric conductivity samples. Moreover, the method was successfully applied to high ionic strength samples such as rock digest, sea water, soy sauce and isotonic drinks.Laboratorio de Investigación y Desarrollo de Métodos AnalÃticos (LIDMA
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