Search results for "57"
showing 10 items of 4186 documents
Caracterización estructural y funcional de los promotores humanos SREBP1 y su regulador INSIG2
2009
La homeostasis lipídica está regulada por factores de transcripción llamados Proteínas de unión a elementos de respuesta a esteroles ó SREBP. Estas porteínas activan a nivel transcripcional enzimas de las vías de síntesis de colesterol, ácidos grasos, triglicéridos y fosfolípidos. Además estos factores regulan la diferenciación adipocitaria y la expresión génica dependiente de insulina. Alteraciones funcionales en SREBP han sido relacionadas con el desarrollo de diversas patologías metabólicas humanas como la obesidad y la diabetes tipo 2. Existen tres miembros de la familia SREBP. Las variantes SREBP1a y SREBP1c, son producidas por splicing alternativo a partir de un único gen mientras que…
Cambios en la fosforilación de proteínas nucleares y cascadas de señalización inducidos por el ácido retinoico
2009
La vitamina A, a partir de una serie de transformaciones metabólicas, se convierte en el ácido retinoico (RA), su metabolito activo más potente biológicamente. La vitamina A y sus derivados juegan un importante papel como reguladores fisiológicos de un gran número de procesos biológicos. Concretamente, el RA posee un papel relevante en el desarrollo embrionario temprano y en la generación de varios órganos y sistemas, como es el caso del Sistema Nervioso. El RA es capaz de inducir la parada proliferativa y la diferenciación in vitro de líneas celulares de muy diferente origen, incluyendo muchos tipos celulares tumorales como el neuroblastoma. Estudios previos realizados en la línea celular …
Estudio teórico de procesos fotoinducidos en sistemas biológicos
2009
En la presente Tesis Doctoral se investiga, desde un punto de vista teórico, procesos de transferencia de carga y/o energía inducida por la luz en distintos sistemas biológicos. En concreto se estudian tres procesos paradigmáticos: la transferencia de carga en la fotosíntesis, la fotofísica y fotorreactividad de las bases nitrogenadas del DNA y el proceso de fotoisomerización del cromóforo de la Rodopsina, desencadenante de la visión. La metodología empleada para la realización de estos estudios es principalmente la CASPT2//CASSCF, una herramienta químico-cuántica especialmente adecuada para el tratamiento de los estados moleculares excitados, debido a su carácter multiconfiguracional.
Bicausative matrices to measure structural change: Are they a good tool?
1999
The causative-matrix method to analyze temporal change assumes that a matrix transforms one Markovian transition matrix into another by a left multiplication of the first matrix; the method is demand-driven when applied to input-output economics. An extension is presented without assuming the demand-driven or supply-driven hypothesis. Starting from two flow matrices X and Y, two diagonal matrices are searched, one premultiplying and the second postmultiplying X, to obtain a result the closer as possible to Y by least squares. The paper proves that the method is deceptive because the diagonal matrices are unidentified and the interpretation of results is unclear. Keywords : Input-Output ; Ch…
Forecast Output Coincidence and Biproportion: Two Criteria to Determine the Orientation of an Economy. Comparison for France (1980-1997)
2002
International audience; The method of forecast output coincidence used to determine if sectors are demand-sided or supply-sided in an input-output framework mixes two effects, the structural effect (choosing between demand and supply side models) and the effect of an exogenous factor (final demand or added-value). The note recalls that another method is possible, the comparison of the stability of technical and allocation coefficients, generalized by the biproportional filter: if for a sector, after biproportional filtering, column coefficients are more stable than row coefficients, then this sector is declared as not supply-sided (but one cannot decide that it is demand-sided anyway), and …
A biproportional filter to compare technical and allocation coefficient variations
1997
International audience; In input-output analysis there are two alternate possibilities between Leontief's mechanism (fixed technical coefficients) and Ghosh's mechanism (fixed allocation coefficients). Testing the long term consistency of these mechanisms entails comparing input-output matrices over time. This paper challenges the value of proportional filters (separate comparison of column and row coefficients) and introduces the biproportional filter which allows simultaneous comparison of column and rows. An application is proposed using French input-output tables for 1980 and 1993. The stability of column coefficients cannot be taken for granted and generally, for any sector, both rows …
About the criteria of output coincidence for forecasts to determine the orientation of the economy (application for France, 1980-1997)
2000
This note indicates that the method of output coincidence for forecasts used to determine if sectors are demand-driven or supply-driven in an input-output framework mixes two effects, the structural effect (choosing between demand and supply driven models) and the effect of an exogenous factor (final demand or added-value). The note recalls that another method is possible, the comparison of the stability of technical and allocation coefficients, generalized by the biproportional filter: if for a sector, after biproportional filtering, column coefficients are more stable than row coefficients, then this sector is declared as not supply-driven (but one cannot decide that it is demand-driven a…
Early Low-Fat Diet Enriched With Linolenic Acid Reduces Liver Endocannabinoid Tone and Improves Late Glycemic Control After a High-Fat Diet Challenge…
2016
International audience; Evidence suggests that alterations of glucose and lipid homeostasis induced by obesity are associated with the elevation of endocannabinoid tone. The biosynthesis of the two main endocannabinoids, N-arachidonoylethanolamine and 2-arachidonoyl-glycerol, which derive from arachidonic acid, is influenced by dietary fatty acids (FAs). We investigated whether exposure to n-3 FA at a young age may decrease tissue endocannabinoid levels and prevent metabolic disorders induced by a later high-fat diet (HFD) challenge. Three-week-old mice received a 5% lipid diet containing lard, lard plus safflower oil, or lard plus linseed oil for 10 weeks. Then, mice were challenged with a…
Chronic exposure of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) induces an obesogenic effect in C57BL/6J mice fed a high fat diet
2017
IF 3.582; International audience; Contaminant involvement in the pathophysiology of obesity is widely recognized. It has been shown that low dose and chronic exposure to endocrine disruptor compounds (EDCs) potentiated diet- induced obesity. High and acute exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), a persistent organic pollutant (POP) and an EDC with anti-estrogenic property, causes wasting syndrome . However at lower doses, the TCDD metabolic effects remain poorly understood. We investigated the obesogenic effect during chronic exposure of TCDD at 1μg/kg body weight (bw)/week in adult C57BL/6J mice fed with a high fat diet (HFD) and exposed from 10 to 42 weeks old to TCDD or e…
Bile acid receptor TGR5 is critically involved in preference for dietary lipids and obesity
2020
International audience; We investigated the implication of Takeda G protein-coupled receptor 5 (TGR5) in fat preference and fat sensing in taste bud cells (TBC) in C57BL/6 wild-type (WT) and TGR5 knock out (TGR5-/-) male mice maintained for 20 weeks on a high-fat diet (HFD). We also assessed the implication of TGR5 single nucleotide polymorphism (SNP) in young obese humans. The high-fat diet (HFD)-fed TGR5-/- mice were more obese, marked with higher liver weight, lipidemia and steatosis than WT obese mice. The TGR5-/- obese mice exhibited high daily food/energy intake, fat mass and inflammatory status. WT obese mice lost the preference for dietary fat, but the TGR5-/- obese mice exhibited n…