RESUMEN
From a prospective and multicentric French cohort, we proposed an external validation study for the expanded criteria donor (ECD), based on 4833 kidney recipients transplanted for the first time between 2000 and 2014. We estimated the subject-specific effect from a multivariable Cox model. We confirmed a 1.75-fold (95% confidence interval [CI] 1.53-2.00, P < .0001) increase in graft failure risk if a given patient received an ECD graft compared to a graft from a donor with standard criteria (standard criteria donor [SCD]). Complementarily, we estimated the population-average effect using propensity scores. We estimated a 1.34-fold (95% CI 1.09-1.64, P = .0049) increase in graft failure risk among ECD patients receiving an ECD graft compared to receiving a SCD graft. With a 10-year follow-up, it corresponded to a decrease of 8 months of the mean time to graft failure due to ECD transplantation (95% CI 2-14 months). The population-average relative risk due to ECD transplantation and the corresponding absolute effect seem finally not so high. Regarding the increase of quality of life in transplantation, our study constitutes an argument to extend the definition of marginality by considering more grafts at high risk and thereby enlarging the pool of kidney grafts.
Asunto(s)
Rechazo de Injerto/mortalidad , Fallo Renal Crónico/cirugía , Trasplante de Riñón/mortalidad , Puntaje de Propensión , Donantes de Tejidos/provisión & distribución , Obtención de Tejidos y Órganos/métodos , Obtención de Tejidos y Órganos/estadística & datos numéricos , Adulto , Anciano , Selección de Donante , Femenino , Estudios de Seguimiento , Rechazo de Injerto/etiología , Rechazo de Injerto/patología , Supervivencia de Injerto , Humanos , Trasplante de Riñón/efectos adversos , Masculino , Persona de Mediana Edad , Pronóstico , Estudios Prospectivos , Calidad de Vida , Factores de Riesgo , Tasa de Supervivencia , Factores de Tiempo , Obtención de Tejidos y Órganos/normas , Receptores de TrasplantesRESUMEN
Ghrelin is a 28-amino-acid peptide secreted during starvation by gastric cells. Ghrelin physiologically induces food intake and seems to alter lipid and glucid metabolism in several tissues such as adipose tissue and liver. Liver has a key position in lipid metabolism as it allows the metabolic orientation of fatty acids between oxidation and esterification. We investigated the effects of peripheral ghrelin administration on 2 crucial parameters of fatty acid oxidation: the levocarnitine (L-carnitine)-dependent entry of the fatty acids in the mitochondria and the mitochondrial fatty acid oxidation. Ghrelin was either given to rats prior to the hepatocyte preparation and culture or used to treat hepatocytes prepared from control animals. Direct incubation of ghrelin to raw hepatocytes did not induce any change in the studied parameters. In hepatocytes prepared from 3 nmol ghrelin-treated rats, a 44% reduction of the mitochondrial fatty acid oxidation while no alteration of the L-carnitine-related parameters were observed. These results suggested (a) that ghrelin has no direct effect on liver, and (b) that when administrated to a whole organism, ghrelin may alter the lipid metabolism and the energy balance through a marked decrease in liver fatty acid oxidation.
Asunto(s)
Ácidos Grasos/metabolismo , Metabolismo de los Lípidos/efectos de los fármacos , Mitocondrias Hepáticas/efectos de los fármacos , Hormonas Peptídicas/farmacología , Animales , Transporte Biológico/efectos de los fármacos , Carnitina/farmacología , Células Cultivadas , Metabolismo Energético/efectos de los fármacos , Ghrelina , Mitocondrias Hepáticas/metabolismo , Oxidación-Reducción/efectos de los fármacos , Ratas , Ratas WistarRESUMEN
The carnitine system plays a key role in beta-oxidation of long-chain fatty acids by permitting their transport into the mitochondrial matrix. The effects of hypothyroidism and hyperthyroidism were studied on gamma-butyrobetaine hydroxylase (BBH), the enzyme responsible for carnitine biosynthesis in the rat. In rat liver, BBH activity was decreased in the hypothyroid state and increased in hyperthyroid animals. The modifications in BBH activity correlated with changes in the enzyme Vmax values. These changes were shown to be related to hepatic BBH mRNA abundance. Thyroid hormones are known to interact with lipid metabolism, in particular by increasing long-chain fatty acid oxidation through activation of carnitine-dependent fatty acid import into mitochondria. Our study showed that thyroid hormones also increased carnitine bioavailability.
Asunto(s)
Carnitina/metabolismo , Regulación Enzimológica de la Expresión Génica/efectos de los fármacos , Oxigenasas de Función Mixta/metabolismo , Hormonas Tiroideas/farmacología , Animales , Cinética , Hígado/enzimología , Masculino , Oxigenasas de Función Mixta/biosíntesis , Oxigenasas de Función Mixta/genética , Especificidad de Órganos , ARN Mensajero/genética , ARN Mensajero/metabolismo , Ratas , Glándula Tiroides/efectos de los fármacos , Glándula Tiroides/metabolismo , gamma-Butirobetaína DioxigenasaRESUMEN
Carnitine is involved in the transfer of fatty acids across mitochondrial membranes. Carnitine is found in dairy and meat products, but is also biosynthesized from lysine and methionine via a process that, in rat, takes place essentially in the liver. After intestinal absorption or hepatic biosynthesis, carnitine is transferred to organs whose metabolism is dependent on fatty acid oxidation, such as heart and skeletal muscle. In skeletal muscle, carnitine concentration was found to be 50 times higher than in the plasma, implicating an active transport system for carnitine. In this study, we characterized this transport in isolated rat myotubes, established mouse C2C12 myoblastic cells, and rat myotube plasma membranes and found that it was Na(+)-dependent and partly inhibited by a Na(+)/K(+) ATPase inhibitor. L-carnitine analogues such as D-carnitine and gamma-butyrobetaine interfere with this system as does acyl carnitine. Among these inhibitors, the most potent was mildronate (3-(2,2,2-trimethylhydrazinium)propionate), known as a gamma-butyrobetaine hydroxylase inhibitor. It also induced a marked decrease in carnitine transport into muscle cells. Removal of carnitine or treatment with mildronate induced growth inhibition of cultured C2C12 myoblastic cells. These data suggest that myoblast growth and/or differentiation is dependent upon the presence of carnitine.
Asunto(s)
Carnitina/metabolismo , Metilhidrazinas/farmacología , Músculo Esquelético/metabolismo , Animales , Transporte Biológico/efectos de los fármacos , División Celular/efectos de los fármacos , Membrana Celular/metabolismo , Células Cultivadas , Técnicas In Vitro , Masculino , Ratones , Músculo Esquelético/citología , Músculo Esquelético/efectos de los fármacos , Ratas , Ratas WistarRESUMEN
Carnitine biosynthesis from lysine and methionine involves five enzymatic reactions. gamma-butyrobetaine hydroxylase (BBH; EC 1.14. 11.1) is the last enzyme of this pathway. It catalyzes the reaction of hydroxylation of gamma-butyrobetaine to carnitine. The cDNA encoding this enzyme has been isolated and characterized. The cDNA contained an open reading frame of 1161 bp encoding a protein of 387 amino acids with a deduced molecular weight of 44.5 kDa. The sequence of the cDNA showed an important homology with the human cDNA recently isolated. Northern analysis showed gamma-butyrobetaine hydroxylase expression in the liver and in some extend in the testis and the epididymis. During this study, it also appeared that BBH mRNA expression was undetectable by Northern analysis during the perinatal period. During the development of the rat, the amount of BBH mRNA appeared after the weaning of the young rat and reached a maximal expression at the adult stage.
Asunto(s)
Hígado/enzimología , Oxigenasas de Función Mixta/genética , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Clonación Molecular , ADN Complementario/química , ADN Complementario/aislamiento & purificación , Regulación del Desarrollo de la Expresión Génica , Masculino , Oxigenasas de Función Mixta/química , Datos de Secuencia Molecular , Ratas , Ratas Wistar , Alineación de Secuencia , Homología de Secuencia de Aminoácido , Homología de Secuencia de Ácido Nucleico , gamma-Butirobetaína DioxigenasaRESUMEN
The biosynthesis of carnitine from lysine and methionine involves five enzymatic reactions. Gamma-butyrobetaine hydroxylase (BBH; EC 1.14.11.1) is the last enzyme of this pathway. It catalyzes the reaction of hydroxylation of gamma-butyrobetaine to carnitine. This enzyme had never been purified to homogeneity from rat tissue. This paper describes the purification and characterization of the rat liver BBH. This protein has been purified some 413 fold by ion exchange, affinity and gel-filtration chromatographies and appears as a dimere of 43,000 Daltons subunits by PAGE. The affinity chromatography column used in the purification process utilizes 3-(2,2,2-trimethylhydrazinium)propionate (THP), a BBH inhibitor, as the ligand. Polyclonal antibodies were raised against the liver enzyme. They were able to precipitate BBH activity in either a crude liver extract or a purified fraction of the enzyme. Furthermore, it crossreacts with a 43 kDa protein in the liver. No evidence for extra hepatic enzyme was found.
Asunto(s)
Carnitina , Hígado/enzimología , Oxigenasas de Función Mixta/aislamiento & purificación , Animales , Ácido Ascórbico/farmacología , Betaína/análogos & derivados , Betaína/metabolismo , Catalasa/metabolismo , Catálisis , Cromatografía de Afinidad , Inhibidores Enzimáticos/metabolismo , Compuestos Ferrosos/farmacología , Hidroxilación , Ácidos Cetoglutáricos/metabolismo , Cinética , Ligandos , Masculino , Metilhidrazinas/metabolismo , Peso Molecular , Ratas , Ratas Wistar , gamma-Butirobetaína DioxigenasaRESUMEN
Recently, we reported on the design, synthesis, and structure-activity relationships of a series of spiroimidazolines endowed with alpha-adrenergic agonist activities. Among the compounds described, (R,S)-spiro(1,3-diazacyclopent-1-ene)-[5,2'](7'-methyl-1'2',3', 4',-tetrahydronaphthalene) fumarate (5RS) was chosen for further development as a venotonic agent. The resolution of this compound, as well as the pharmacological characterization of the enantiomers, stereospecific synthesis of eutomer (5S, S 18149), and determination of absolute configuration by single-crystal X-ray diffraction analysis, are described.
Asunto(s)
Agonistas alfa-Adrenérgicos/química , Presión Sanguínea/efectos de los fármacos , Músculo Liso Vascular/fisiología , Tetrahidronaftalenos/química , Agonistas alfa-Adrenérgicos/síntesis química , Agonistas alfa-Adrenérgicos/farmacología , Animales , Cristalografía por Rayos X , Arteria Femoral/efectos de los fármacos , Técnicas In Vitro , Espectroscopía de Resonancia Magnética , Modelos Moleculares , Conformación Molecular , Estructura Molecular , Contracción Muscular/efectos de los fármacos , Músculo Liso Vascular/efectos de los fármacos , Fenilefrina/farmacología , Prazosina/farmacología , Ratas , Vena Safena/efectos de los fármacos , Vena Safena/patología , Estereoisomerismo , Relación Estructura-Actividad , Tetrahidronaftalenos/síntesis química , Tetrahidronaftalenos/farmacología , Yohimbina/farmacologíaRESUMEN
Hybridization of a poorly immunogenic tumor cell with an allogeneic cell was performed in order to improve tumor immune response; several variants derived from one hybrid tumor cell were studied. We compared the immunogenicity of these variants and their allogeneic and syngeneic class I antigen expression before and after IFN gamma treatment. Allogeneic class I antigens were weakly expressed in all variants; IFN treatment enhanced their expression similarly in both immunogenic and nonimmunogenic variants. Syngeneic class I antigen expression differed among variants: IFN treatment induced changes in their expression which corresponded to a posttranscriptional event and which could, at least partly, explain the modifications observed in their immunogenicity.