9 resultados
Resultados de la búsqueda
Mostrando 1 - 9 de 9
Ítem ¿Por qué si el agua es transparente uno ve el mar azul? Lo que se preguntan los niños sobre ciencias contestado en breves relatos de expertos(Universidad Icesi, 2020-10-01) Rodríguez Santa, Laura María; Ávila Jiménez, Isabel Cristina; Londoño, Gustavo; Tavera, José; Escobar Flórez, Sebastián; Loaiza Muñoz, Mario Agustín; Rojas Díaz, Vladimir; Herrera, Leonardo; Barrera, Edgar; Castaño Astudillo, Alejandro; Sánchez G., J. Camilo; Ocampo, Clara; Valderrama, Carlos; Díaz Vasco, Oswaldo; Guevara Cano, Gloria Elizabeth; Cadena D., Zeneire; Cantera, Jaime; Rengifo, Juliana; Estrada Gaviria, Luis Felipe; Pizano Gómez, Camila; Montoya Peláez, Guillermo León; Rojas, Giovanni; Rueda Upegui, Gustavo Adolfo; Lombana Martínez, Oscar Iván; Cuellar, José Luis; Navia, Joaquín; Murillo Yepes, Gustavo; Triana, Hernán; Fernández, Jhonattan; Pérez, Alejandra; Burgos, Isabella; Rivas Marín, María Isabel; Negret, Juan Pablo; Guarín Sepúlveda, Marino Hernando; Yaker Agudelo, Hendel; Madrid Molina, Juan Manuel; Rivas Marín, María Isabel; Cardona Abrego, Maristela; Guerrero Yepes, Marcela; Gómez Paz, Luis DavidEste libro, cuyo título es precisamente una de las preguntas de los niños, una de aquellas que quizás nos hicimos cuando teníamos esas edades, nos mostró lo cerca que está la ciencia de cada uno, todas las inquietudes que se tienen sobre la misma y la oportunidad que tenemos si enriquecemos la escuela con espacios que permitan aprovechar dichas preguntas para enseñarles a pensar a nuestros niños, a despertar su curiosidad y a seguir teniendo ideas maravillosas.
Ítem Residuos agroindustriales y bioeconom en el Valle del Cauca. Fuentes renovables de biomateriales a partir de subproductos de la industria azucarera(Universidad de Cartagena, 2014-05-21) XII Congreso Colombiano de Fitoquímica; Montoya Peláez, Guillermo LeónEs evidente que nuestro pa tiene vocaci agrola y actualmente el gobierno nacional tiene priorizadas ciertas cadenas productivas entre las cuales se encuentra la ca de azar focalizada en m de 200 mil hecteas sembradas principalmente en el Valle del Cauca. La bioeconom por otro lado es un concepto relativamente reciente que visualiza el procesamiento sustentable de la biomasa para obtener biocombustibles, energ tmica, compuestos quicos y materiales con distintos fines productivos. Aplicando el concepto de bioeconom y considerando las cifras de residuos producidos por el sector azucarero colombiano (genera alrededor de 50 mil toneladas de residuos/d), proponemos el diagntico de un metabolito secundario desperdiciado a lo largo de su paso por el proceso de producci de azar y la fabricaci de biomateriales a partir de esta fuente renovable. En el desarrollo de este proyecto de investigaci se validun modo moderno de anisis (SPE-UPLC-ELSD) para valorar 7 etapas del proceso de extracci de azar de un ingenio azucarero. Esta evaluaci permitidefinir los puntos m probables de recuperaci sin interferir con el proceso de producci de la empresa en donde se realizel diagntico. Adicionalmente se estableciun mecanismo de reacci para la generaci de un biopolero hiper-ramificado a partir de este residuo. Estos resultados demuestran la factibilidad de aplicar conceptos de bioeconom en los sectores agrolas m promisorios del territorio nacional y generar nuevas fuentes de crecimiento econico de cara a la apertura comercial en la cual Colombia se encuentra sumergida.Ítem Atherosclerosis development in SLE patients is not determined by monocytes ability to bind/endocytose Ox-LDL.(2011-06-14) Montoya Peláez, Guillermo LeónPatients with systemic lupus erythematosus (SLE) have a high risk of developing cardiovascular disease; however, the mechanisms involved in the early onset of atherosclerosis in these patients are not clear. Scavenger receptors, CD36 and CD163 are expressed by mononuclear phagocytes and participate in the binding and uptake of oxidized low-density lipoproteins (Ox-LDL), contributing to foam-cells formation and atherosclerosis development. The aim of the present study was to evaluate CD36(+) and CD163(+) expression and Ox-LDL removal by monocytes from SLE and atherosclerotic patients, compared to similar age-range healthy controls. Healthy controls, SLE, and atherosclerotic patients were evaluated for carotid intima media thickness (CIMT), lipid profile, and native LDL (N-LDL) and Ox-LDL binding/endocytosis. SLE patients presented decreased high-density lipoproteins (HDL) and increased Triglyceride levels, and half of the SLE patients had increased CIMT, compared to their healthy controls (HC(SLE)). The number of CD14(+)CD163(+) cells was increased in atherosclerosis healthy controls (HC(Atheros)) compared to HC(SLE), but there were no differences between SLE or atherosclerotic patients and their respective healthy controls. Clearance assays revealed a similar capacity to bind/endocytose Ox-LDL by monocytes from SLE patients and HC(SLE), and an increased binding and endocytosis of Ox-LDL by monocytes from atherosclerotic patients, compared to HC(Atheros). The decreased CD36 and CD163 expression observed in atherosclerotic and SLE patients, respectively, suggest that these inflammatory conditions modulate these receptors differentially. The increased CIMT observed in SLE patients cannot be explained by Ox-LDL binding/endocytosis, which was comparable to their controls.Ítem Business-Design Laboratory: a Strategy for Innovation(2011-12-01) Montoya Peláez, Guillermo LeónThe contribution of industrial design schools to the development of innovative products is well known around the industrialized world. In Latin American countries like Colombia, industrial design is a relatively young practice and the market is not yet aware of the importance of design as a factor for innovation. Colombia’s industry creativity is just emerging. For many years focus was put on production and contract manufacturing. Today, however, Eastern countries do it on a more larger-scale and at low prices. This condition has forced the academia to look for ways of linking companies with students and thus, developing more competitive innovation products.Ítem HPLC-ESI-IT-MS/MS Analysis and Biological Activity of Triterpene Glycosides from the Colombian Marine Sponge Ectyoplasia ferox(Multidisciplinary Digital Publishing Institute, 2013-09-01) Montoya Peláez, Guillermo LeónThe marine sponge Ectyoplasia ferox produces antipredatory and allelopathic triterpenoid glycosides as part of its chemical defense repertoire against predators, competitors, and fouling organisms. These molecules are responsible for the pharmacological potential found in the glycosides present in this species. In order to observe the glycochemical diversity present in E. ferox, a liquid chromatography coupled to a tandem mass spectrometry approach to analyse a complex polar fraction of this marine sponge was performed. This gave valuable information for about twenty-five compounds three of which have been previously reported and another three which were found to be composed of known aglycones. Furthermore, a group of four urabosides, sharing two uncommon substitutions with carboxyl groups at C-4 on the terpenoid core, were identified by a characteristic fragmentation pattern. The oxidized aglycones present in this group of saponins can promote instability, making the purification process difficult. Cytotoxicity, cell cycle modulation, a cell cloning efficiency assay, as well as its hemolytic activity were evaluated. The cytotoxic activity was about IC50 40 µg/mL on Jurkat and CHO-k1 cell lines without exhibiting hemolysis. Discussion on this bioactivity suggests the scanning of other biological models would be worthwhile.Ítem O -glycoside sequence of pentacyclic triterpene saponins from Phytolacca bogotensis using HPLC-ESI/multi-stage tandem mass spectrometry(Wiley, 2009-07-23) Holzgrabe, UlrikeThe lack of pharmacopoeial methodologies for the quality control of plants used for therapeutic purposes is a huge problem that impacts directly upon public health. In the case of saponins, their great structural complexity, weak glycoside bonds and high polarity hinder their identification by conventional techniques. To apply high-performance liquid chromatography-electrospray tandem mass spectrometry (HPLC-ESI/MS(n)) to identify the O-glycoside sequence of saponins from the roots of Phytolacca bogotensis. Saponins were isolated by preparative HPLC and characterised by NMR spectroscopic experiments. Collision-induced dissociation (CID) of isolated saponins was performed producing typical degradation reactions that can be associated with several glycosidic bonds as empirical criteria. A method using solid-phase extraction (SPE) and HPLC/ESI-MS(n) for the characterisation of saponins and identification of novel molecules is described. Three saponins reported for the first time in P. bogotensis were isolated and characterised by NMR spectroscopy. Characteristic cross ring cleavage reactions have been used as empirical criteria for the characterisation of the glycosidic bonds most frequently reported for Phytolacca saponins. One new saponin was proposed on the basis of empirical criteria, and other five saponins were identified for the first time for P. bogotensis using HPLC-ESI/MS(n). Electrospray ionisation in combination with tandem mass spectrometry has been established as a powerful tool for the profiling of saponins from roots of P. bogotensis. CID proved to be a useful tool for the characterisation and identification of known and novel saponins from the plant family Phytolaccaceae and can be used for quality control purposes of crude plant extracts.Ítem Pentacyclic triterpenes from Cecropia telenitida with immunomodulatory activity on dendritic cells(Sociedade Brasileira de Farmacognosia, 2013-09-01) Montoya Peláez, Guillermo LeónPentacyclic triterpene Natural product Cytokine modulation Anti-inflammatory activity Dendritic cells Pentacyclic triterpenes are a large family of plant metabolites that exhibit a wide array of biological activities. The genus Cecropia,which encompasses many plant species, has been used as traditional medicine for the treatment of inflammatory diseases and is known to produce many active pentacyclic triterpenes. In this study we investigated the chemical composition of a pentacyclic triterpene fraction from the roots of Cecropia telenitida Cuatrec., Urticaceae. A novel compound, which we termed yarumic acid, and four known molecules (serjanic acid, spergulagenic acid A, 20-hydroxy-ursolic acid and goreishic acid I) were isolated and characterised. In a dendritic cell (DC)based assay, we demonstrated that non-toxic doses of these pentacyclic triterpenes inhibited the secretion of at least one of the proinflammatory cytokines tested (IL-1β, IL-12p40, IL-12p70, TNF-α). Spergulagenic acid A also inhibited nitric oxide production in lipopolysaccharide-stimulated dendritic cell. Serjanic acid and spergulagenic acid A, which were the most potent abundant compounds in the pentacyclic triterpene fraction, showed the most activity in the dendritic cell-based assay.Ítem Quantitation of trans -aconitic acid in different stages of the sugar-manufacturing process.(American Chemical Society, 2014-08-06) Montoya Peláez, Guillermo León; Izquierdo, Olga; Cortés, Paola; Londono, JulyThe sugar cane industry has seen how biomass production in sugar mills would be converted to a readily available source of molecules besides sugar. Properly managed, byproducts would be transformed into a sustainable source of renewable and environmentally friendly chemical products.1 As a principal and more abundant organic acid in sugar cane juice, trans-aconitic acid (TAA) has been studied for use as a plasticizer in the polymer industry.2 However, up to now no industrial-scale application has been reported. As a reasonable approach to recover TAA from a sugar mill, first, an analytical method to determine its presence in all stages of the sugar-manufacturing process is needed. A new modern method was developed to measure TAA in seven stages in a sugar mill located in Valle del Cauca, Colombia. The stages with higher content of TAA were syrup, with 3363.6 ± 589.3 mg/L, and honey (molasses), with 6110.05 ± 139.5 mg/L. © 2014 American Chemical Society.Ítem Rapid differentiation of isobaric and positional isomers of structurally related glycosides from Phytolacca bogotensis.(Wiley, 2009-09-25) Arango Mambuscay, Carlos AlbertoThrough the action of glycosyltransferases, a plant can biosynthetically assemble small different aglycons or 'templates' to various polysaccharides to produce numerous glycoconjugates differing in the type of the attached aglycon, the anomeric configuration of C-1 of the glycosylating sugar, the type of sugar and the different position of attachments of the sugar unit present in the polysaccharide chain. The position of attachments and the anomeric configuration of the different sugar present in the polysaccharide create the opportunity to generate molecules with either the same or very close molecular weights, which have relative structural similarity--forming isobaric and positional isomers. Although isomeric differentiation was once considered outside of the domain of mass spectrometry, this task can now be resolved using tandem mass spectrometry. In a standardized purified glycoconjugate fraction (SPT01) from Phytolacca bogotensis, we report conventional electrospray ionization mass spectrometry and collision-induced dissociation (CID) MS/MS parameters which favored the formation of characteristic product ions. This allowed us to suggest the type of sugar linkages present in a specific glycoconjugate. Ten new glycoconjugate are described from this plant and another twelve known saponins were structurally characterized using the automatic MSn acquisition mode. The differentiation of two pairs of positional isomers and four isobaric glycosides and the production of a library of 30 glycosides present in P. bogotensis were accomplished.