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Search Results: 1 - 10 of 408149 matches for " Ruiz Márquez "
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Sensory Stimulation-Dependent Plasticity in the Cerebellar Cortex of Alert Mice
Javier Márquez-Ruiz, Guy Cheron
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0036184
Abstract: In vitro studies have supported the occurrence of cerebellar long-term depression (LTD), an interaction between the parallel fibers and Purkinje cells (PCs) that requires the combined activation of the parallel and climbing fibers. To demonstrate the existence of LTD in alert animals, we investigated the plasticity of local field potentials (LFPs) evoked by electrical stimulation of the whisker pad. The recorded LFP showed two major negative waves corresponding to trigeminal (broken into the N2 and N3 components) and cortical responses. PC unitary extracellular recording showed that N2 and N3 occurred concurrently with PC evoked simple spikes, followed by an evoked complex spike. Polarity inversion of the N3 component at the PC level and N3 amplitude reduction after electrical stimulation of the parallel fiber volley applied on the surface of the cerebellum 2 ms earlier strongly suggest that N3 was related to the parallel fiber–PC synapse activity. LFP measurements elicited by single whisker pad stimulus were performed before and after trains of electrical stimuli given at a frequency of 8 Hz for 10 min. We demonstrated that during this later situation, the stimulation of the PC by parallel and climbing fibers was reinforced. After 8-Hz stimulation, we observed long-term modifications (lasting at least 30 min) characterized by a specific decrease of the N3 amplitude accompanied by an increase of the N2 and N3 latency peaks. These plastic modifications indicated the existence of cerebellar LTD in alert animals involving both timing and synaptic modulations. These results corroborate the idea that LTD may underlie basic physiological functions related to calcium-dependent synaptic plasticity in the cerebellum.
Oxidación en sistemas lipídicos heterofásicos: emulsiones aceite en agua
Velasco, J.,Dobarganes, M. C.,Márquez-Ruiz, G.
Grasas y Aceites , 2002,
Abstract: Lipid oxidation is the major form of deterioration in foods because it decreases food quality and nutritional value, and may have negative health implications. However, variables affecting lipid oxidation in heterophasic lipid systems are scarcely known, and they are of particular interest in the case on oil-in-water emulsions since these lipid systems constitute a large number of foods, e.g., milks, creams, mayonnaisea s, soups and sauces. In this paper, the present state of the art on lipid oxidation in oil-in-water emulsions is revised, including description of the variables specifically involved in oxidation of these lipid systems (pH, presence of interface, partition of reactants and products, interaction with other components) as well as those affecting lipid oxidation in general but showing particular characteristics in their action in emulsions (oxygen, unsaturation degree, presence of antioxidants and prooxidants). La oxidación lipídica es la alteración más importante que ocurre en los alimentos porque disminuye su calidad y valor nutritivo, y puede tener consecuencias negativas para la salud. Sin embargo, las variables que afectan a la oxidación en sistemas lipídicos heterofásicos son poco conocidas y, en particular, poseen gran interés en el caso de las emulsiones aceite en agua ya que estos sistemas lipídicos constituyen un elevado número de alimentos, por ejemplo, leches, natas, mayonesas, sopas y salsas. En este trabajo, se revisa la situación actual del conocimiento sobre oxidación en emulsiones aceite en agua, incluyendo la descripción de las variables implicadas específicamente en la oxidación de estos sistemas (pH, presencia de la interfase, partición de reactivos y productos, interacciones con otros componentes) así como de las variables que afectan a la oxidación de los lípidos en general pero cuya acción en emulsiones presenta características particulares (oxígeno, grado de insaturación, presencia de antioxidantes y prooxidantes).
Characterization, quantitation and evolution of monoepoxy compounds formed in model systems of fatty acid methyl esters and monoacid triglycerides heated at high temperature
Berdeaux, O.,Márquez-Ruiz, G.,Dobarganes, M. C.
Grasas y Aceites , 1999,
Abstract: Monoepoxy compounds formed after heating methyl oleate and linoleate, triolein and trilinolein at 180°C for 5, 10 and 15 hours, were characterized and quantitated after derivatization to fatty acid methyl esters by using two base-catalyzed procedures. Structures were identified by GC-MS before and after hydrogénation. A complete recovery of the epoxy compounds was obtained by comparing results from methyl oleate and linoleate before and after transesterification, and good repeatability was also attained. Similar amounts of epoxides were found for methyl esters and triglycerides of the same degree of unsaturation, although formation was considerably greater for the less unsaturated substrates, methyl oleate and triolein, possibly due to the absence of remaining double bonds in the molecule which would involve a lower tendency to participate in further reactions. On other hand, independently of the degree of unsaturation of the model systems and of the period of heating, significantly higher amounts of trans isomers were formed. Finally from comparison between the amounts of epoxides and the level of polar fatty acids in samples, it was deduced that monoepoxy compounds were one of the major groups formed under the conditions used. En este estudio se identifican y cuantifican los compuestos epoxidados formados a partir de sistemas modelo de oleato y linoleato de metilo, trioleína y trilinoleína, calentados a 180°C durante 5,10 y 15 horas. La identificación se lleva a cabo mediante CG-EM en las muestras de esteres metílicos antes y después de someter a hidrogenación y para su cuantificación se utilizan dos procedimientos de transesterificación en medio alcalino. La comparación de las cantidades obtenidas, antes y después de la derivatización de los sistemas modelo de esteres metílicos, permitió deducir que la recuperación fue completa, obteniéndose también una excelente repetibilidad. Las cantidades de epóxidos encontradas fueron del mismo orden para esteres metílicos y triglicéridos del mismo grado de insaturación, aunque la formación fue considerablemente mayor en los sistemas menos insaturados — oleato de metilo y trioleína— posiblemente debido a la ausencia de dobles enlaces en la molécula, que limitaría su participación en posteriores reacciones. Por otra parte, independientemente del grado de insaturación del sustrato y del periodo de calentamiento, se encontraron cantidades significativamente más elevadas de los isómeros trans. Finalmente, es posible deducir, por comparación con la cantidad total de compuestos de degradación, que los epóxidos constit
Application of the accelerated test Rancimat to evaluate oxidative stability of dried microencapsulated oils
Velasco, J.,Dobarganes, M. C.,Márquez-Ruiz, G.
Grasas y Aceites , 2000,
Abstract: The objective of this work was to apply the oxidative test Rancimat to dried microencapsulated oils (DMO), with special emphasis on assessing the efficacy of natural antioxidants. DMO were prepared by freeze-drying emulsions containing sodium caseinate, lactose and fish or sunflower oils, with and without added the antioxidant mixture ALT (ascorbic acid, lecithin and tocopherol). Under the Rancimat working conditions selected for testing DMO (5 g sample, 100 oC and 20 L air/h), excellent repeatability was obtained. The antioxidant effect of ALT was much higher in bulk fish oil than in its counterpart DMO, either in Rancimat or at 30 oC in the dark. Further experiments using Rancimat showed that the moderate increase in stability of DMO added ALT was only attributable to tocopherol while the synergistic actions of lecithin and ascorbic acid were not observed, their action probably depending on their location and orientation in these complex lipid systems. This test enabled to compare monophasic (bulk oils and DMO-extracted oils) and heterophasic lipidic systems (DMO and DMO devoid of the accessible, free oil fraction), thus offering a rapid means to examine the influence of oil distribution and partitioning of antioxidants on oxidative stability. El objetivo de este trabajo es la aplicación del test Rancimat a aceites microencapsulados, con especial interés en el estudio de la eficacia de antioxidantes naturales. Los aceites microencapsulados en matriz seca (DMO) se prepararon mediante liofilización de emulsiones constituidas por caseinato sódico, lactosa y aceite de pescado o girasol, con o sin la mezcla antioxidante ALT (ácido ascórbico, lecitina y tocoferol). En las condiciones seleccionadas en Rancimat (5 g de muestra, 100 oC y 20 L/h aire) se obtuvo excelente repetitividad. La mezcla ALT fue mucho más efectiva en el aceite de pescado que en su correspondiente DMO, tanto en Rancimat como a 30 oC en la oscuridad. Otros experimentos en Rancimat mostraron que el aumento moderado de la estabilidad en DMO que contenían ALT sólo podía atribuirse al tocoferol mientras que la acción sinergista de la lecitina y el ácido ascórbico no se observó, probablemente porque su efecto depende de su localización y orientación en estos sistemas lipídicos complejos. El test permitió comparar sistemas lipídicos monofásicos (aceites originales y los extraídos de DMO) y heterofásicos (DMO y DMO exentos de la fracción lipídica más accesible) y por tanto ofrece una medida rápida de utilidad para estudiar la influencia de la distribución del aceite y partición de antioxidantes
Influencia de la cantidad, calidad y tipo de grasa de la dieta sobre la composición y distribución de ácidos grasos del tejido adiposo de ratas
Salgado, A.,Márquez-Ruiz, G.,Dobarganes, M. C.
Grasas y Aceites , 1992,
Abstract: In this paper the effect of the 3 most important variables (quantity, quality and composition) of dietary fat on the distribution and composition of fatty acids in rat adipose tissue, is studied. From the results obtained after feeding 11 groups of rats, the following conclusions stand out: 1 . - Fatty acid composition of rat adipose tissue is very variable. Nevertheless, when the percentage of fat in the diet is higher than 12%, the fatty acid composition of the adipose tissue is similar to that of the ingested fat. 2.- The level of alteration of the fat in the diet clearly modifies the fat composition In adipose tissue. This fact might be due to the lower digestibility. 3.- Fatty acid distribution in adipose tissue is independent of the distribution in the ingested fat. Se estudia la influencia de las 3 variedades más importantes de la grasa de la dieta (cantidad, calidad y composición) sobre la composición y distribución de ácidos grasos del tejido adiposo, utilizando ratas como animales de experimentación. Los resultados obtenidos a partir de 11 grupos de ratas permiten deducir las siguientes conclusiones: 1. - La composición de ácidos grasos de la grasa del tejido adiposo puede ser muy variable. Contenidos de grasa en la dieta superior al 12% originan un perfil de ácidos grasos en tejido adiposo muy similar al de la grasa ingerida. 2.- La alteración de la grasa de la dieta modifica la composición de ácidos grasos del tejido adiposo, debido a la menor cantidad de grasa absorbida. 3.- La distribución de los ácidos grasos en los triglicéridos del tejido adiposo es independiente de la de la grasa ingerida.
Regulation of used frying fats and validity of quick tests for discarding the fats
Dobargarnes, M. C.,Márquez-Ruiz, G.
Grasas y Aceites , 1998,
Abstract: During deep-fat frying, a complex series of reactions takes place resulting in hydrolysis, oxidation and polymerization of the oil. As quality of fried foods is affected by that of the oil, regulations or guidelines have been established in many countries to guarantee high quality foods. In this lecture, present regulations mainly focusing on oil deterioration and setting limits to alteration compounds are reviewed. Among analytical methods to control oil quality, polar compound and polymer determinations stand out. Studies carried out in different countries indicate the need for improving the quality of frying oil to produce more nutritious fried foods. Practical deep-fat frying can be divided in industrial and fast-food segments, characterized by the use of continuous and discontinuous fryers, respectively. From the analysis of a high number of samples it is deduced that the present situation is very different in both segments and that the main problem is to determine when the fat or oil has to be replaced where there are no laboratory facilities. Hence, simple rapid analytical tests to substitute for official methods are neccesary to monitor oil quality in restaurants and fried food outlets. Data of validity of rapid tests will be presented with particular emphasis on the utility of commercialized kits like Oxifrit-Test and Veri-Fry to improve the quality of frying fats and oils.
Control de calidad de las grasas de fritura. Validez de los métodos de ensayos rápidos en sustitución de la determinación de compuestos polares
Dobarganes, M. C.,Márquez-Ruiz, G.
Grasas y Aceites , 1995,
Abstract: In this paper, substitution of polar compound quantitation by quick tests for discarding used frying fats according to official regulation, is evaluated. Two commercialized tests (VERI-FRY and OXIFRIT) as well as two laboratory tests (PEREVALOV and Solubility in acetone:methanol 90:10) have been applied. Comparison of the results with those obtained for polar compounds indicated that OXIFRIT was the best quick tests as it gave the minimum percentage of enors. Given the present situation, the application of any of the two commercialized tests would contribute to improve frying fat quality. Se estudia la validez de métodos de ensayo rápido para sustituir la determinación de compuestos polares establecida en la Norma de Calidad de aceites y grasas calentados. Dos pruebas comercializadas (VERI-FRY y OXIFRIT) y dos pruebas rápidas de laboratorio (PEREVALOV y Solubilidad en Acetona-Metanol 90:10) fueron aplicadas a un elevado número de muestras. Comparando los resultados obtenidos, con el contenido en compuestos polares, el ensayo denominado OXIFRIT dio el menor número de errores aunque la aplicación de cualquiera de las dos pruebas comercializadas contribuiría a mejorar la calidad de las grasas de fritura.
Oxidation of free and encapsulated oil fractions in dried microencapsulated fish oils
Velasco, J.,Dobarganes, M. C.,Márquez-Ruiz, G.
Grasas y Aceites , 2000,
Abstract: The objective of this work was to evaluate oxidation of dried microencapsulated fish oils (DMFO) during storage at ambient temperature, and to examine the influence of oils distribution (free vs. encapsulated oil) in these complex lipidic systems. DMF0 were prepared by freeze-drying emulsions containing sodium caseinate, lactose and fish oil, with and without adding the antioxidant mixture ALT (ascorbic acid, lecithin and tocopherol). Samples were stored at 25 or 30 oC either in the dark or light with limited, accesible air or under vacuum. The progress of oxidation was followed through quantitation of triglyceride polymers, and oxidation levels of free and encapsulated oil fractions were differentiated. Results showed that oxidation was very rapid both in free and encapsulated oil fractions in all DMFOs exposed to light. In the dark, oxidation was triggered first in the free oil fraction of samples not protected with ALT but, in contrast, samples with ALT showed significantly higher oxidation levels in encapsulated than in free oil fractions, regardless of the limited or free availability of air. These results indicated that addition of the antioxidant system ALT was more effective in the free oil fraction, thus reflecting the great influence of partitioning and/or orientation of antioxidants on their efficacy in complex lipid systems. El objetivo de este trabajo es la evaluación de la oxidación de aceites de pescado microencapsulados en matriz seca (DMFO) durante su almacenamiento a temperatura ambiente, y examinar la influencia de la distribución del aceite (aceite libre frente a aceite encapsulado) en estos sistemas lipídicos complejos. Las muestras se prepararon mediante liofilización de emulsiones constituidas por caseinato sódico, lactosa y aceite de pescado, con o sin la mezcla antioxidante ALT (ácido ascórbico, lecitina y tocoferol); y se almacenaron a 25 o 30 oC a la luz o a la oscuridad, con aire limitado, accesible o al vacío. Para el seguimiento del desarrollo oxidativo se aplicó la cuantificación de los polímeros de triglicéridos, y se diferenciaron los niveles de oxidación de las fracciones de aceite libre y encapsulada. Los resultados mostraron que la oxidación se desarrolló rápidamente en ambas fracciones en las muestras expuestas a la luz. A la oscuridad, la oxidación se disparó primero en la fracción de aceite libre de las muestras no protegidas con ALT pero, en contraste, las muestras con ALT mostraron niveles de oxidación significativamente más al tos en la fracción encapsulada que en la libre, independientemente de la limitación o
Calidad de las grasas de fritura en el sector de restauración de Andalucía
Dobarganes, M. C.,Márquez-Ruiz, G.
Grasas y Aceites , 1995,
Abstract: In this paper, analytical results obtained from 174 frying oil samples collected from 131 fast food shops and restaurants by Food Inspection Services, are summarized. Quantization of polar compounds indicated that about 35% of the samples had alteration levels higher than the limit established in the Spanish regulation for discarding frying fats (25% polar compounds). High levels of oxidized triglycerides and polymeric compounds were found in a significant number of oils which demonstrated the need for improving frying oil quality in this sector. En este trabajo se resumen los resultados de la evaluación de 174 muestras obtenidas por los Servicios de inspección en 143 establecimientos de preparación de alimentos de consumo inmediato. La determinación del porcentaje de compuestos polares Indicó que aproximadamente un 35% de las muestras tuvieron niveles de alteración superiores a los establecidos en la reglamentación espa ola para desechar la grasa (25% de compuestos polares). Los niveles elevados de compuestos de polimerización y oxidación encontrados en un número significativo de muestras, demuestran la necesidad de mejorar la calidad de las grasas de fritura en este sector.
SCORE underestimates cardiovascular risk (CVR) of HIV+ patients
R Ramírez,J Márquez,M Tasias,S Ruiz
Journal of the International AIDS Society , 2012, DOI: 10.7448/ias.15.6.18274
Abstract: The new European Guidelines of Dislipidemia Management of the European Societies of Cardiology and Arteriosclerosis consider HIV+ as patients at high risk of developing cardiovascular events and deaths. The objective of the study was to evaluate cardiovascular events and deaths in a series of HIV+ patients. Observational, cross-sectional study, including a cohort of HIV+ and HIV patients from 2008. CVR was calculated using the SCORE-CVR chart. Variation on lipid profile and incidence of cardiovascular events, cardiovascular death or death related to any cause were recorded. Data was analyzed using SPSS version 20.0 for MAC. 154 HIV+ and 155 HIV patients were included. Mean age: 44.8±9.5 vs 55.2±14.3 y and 69.5% vs 49% males respectively (p<0.01). Mean time since HIV+ diagnosis was 11±6.2 y. Mean BMI and systolic blood pressure were lower in HIV+ (25.1±6.7 kg/m2 vs 28.7±5.1 kg/m2, (p<0.01) and 119.6±19.4 vs 124.7±14.7 mmHg, (p=0.044; respectively)). A lower proportion of hypertense, diabetic and obese patients was observed in HIV+ (25.5% vs 6.5%; 20.6% vs 3.9% and 36.8% vs 12.3%) but a larger proportion of smokers (68.8% vs 29.7%) was observed (p<0.01 in all cases). Mean cholesterol and LDLc were lower in HIV+ (191.2±41.4 vs 218.5±44.6 mg/dl and 109.5±33.9 vs 134.6±37.7 mg/dl; p<0.01; respectively) but with a lower mean HDLc and higher TG (50.3±19 mg/dl vs 55.2±14.9 mg/dl; p=0.013 and 156.7±85.7 vs 135.8±66.2 mg/dl; p=0.017; respectively). There was no significant difference in mean CVR-SCORE (3.5±3.6% vs 4.4±3.8%; p=0.091). With this SCORE, 5.2±5.3 and 6.7±5.8 cardiovascular events or deaths should be expected in HIV+ and HIV respectively at 10 y. Four years later cholesterol, LDLc, HDLc, TG in HIV+ and HIV patients did not vary compared with those obtained 4 y before. 5 events and 1 death were seen at 4 y follow-up in HIV+, and in HIV patients. The incidence of events in HIV+ patients is similar to the expected according to their SCORE at 10 y. We could suppose that once the 10 y follow-up is reached, this incidence would be higher. On the other side, in HIV at 4 y just 3 events ocurred, far from the 6.7 events expected. There were no significant differences between lipid profiles in any of the cohorts. Lipid profile with low HDLc and high TG is persistent in HIV+ patients at 4 y follow-up. Understimation of CVR in HIV+ patients by SCORE charts could be present as soon as 4 y after the first assesment. This supports the stratification of HIV+ patients as high-risk patients in new guidelines.
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