Search results for "PRECIPITATION"
showing 10 items of 826 documents
RNAPol-ChIP: a novel application of chromatin immunoprecipitation to the analysis of real-time gene transcription.
2004
We describe a procedure, RNAPol-ChIP, to measure actual transcriptional rate. It consists of the detection, by chromatin immunoprecipitation (ChIP), of RNA polymerase II within the coding region of genes. To do this, the DNA immunoprecipitated with polymerase antibodies is analysed by PCR, using an amplicon well within the coding region of the desired genes to avoid interferences with polymerase paused at the promoter. To validate RNAPol-ChIP, we compare our results to those obtained by classical methods in several genes induced during either liver regeneration or acute pancreatitis. When short half-life mRNA genes are studied (e.g. c-fos and egr1), RNAPol-ChIP gives results similar to thos…
Transcriptional activation of CYP2C9, CYP1A1, and CYP1A2 by hepatocyte nuclear factor 4alpha requires coactivators peroxisomal proliferator activated…
2006
Hepatocyte nuclear factor 4alpha (HNF4alpha) is a key transcription factor for the constitutive expression of cytochromes P450 (P450s) in the liver. However, human hepatoma HepG2 cells show a high level of HNF4alpha but express only marginal P450 levels. We found that the HNF4alpha-mediated P450 transcription in HepG2 is impaired by the low level of coactivators peroxisomal proliferator activated receptor-gamma coactivator 1alpha (PGC1alpha) and steroid receptor coactivator 1 (SRC1). Reporter assays with a chimeric CYP2C9-LUC construct demonstrated that the sole transfection of coactivators induced luciferase activity in HepG2 cells. In HeLa cells however, CYP2C9-LUC activity only significa…
Vitamin E deficiency induces liver nuclear factor-κB DNA-binding activity and changes in related genes
2005
The biological functions of vitamin E have been classically attributed to its property as a potent inhibitor of lipid peroxidation in cellular membranes. However, in 1991, Azzi's group first described that alpha-tocopherol inhibits smooth muscle cell proliferation in a protein kinase C (PKC)-dependent way, demonstrating a non-antioxidant cell signalling function for vitamin E. More recently, the capacity of alpha-tocopherol to modulate gene expression with the implication of different transcription factors, beyond its antioxidant properties, has also been established. This study was to determine the effect of vitamin E-deficiency on liver nuclear factor-kappa B (NF-kappaB) DNA-binding activ…
Phosphodiesterase 10A in the Rat Pineal Gland: Localization, Daily and Seasonal Regulation of Expression and Influence on Signal Transduction
2010
The cyclic nucleotide phosphodiesterase 10A (PDE10A) is highly expressed in striatal spiny projection neurons and represents a therapeutic target for the treatment of psychotic symptoms. As reported previously [J Biol Chem 2009; 284:7606–7622], in this study PDE10A was seen to be additionally expressed in the pineal gland where the levels of PDE10A transcript display daily changes. As with the transcript, the amount of PDE10A protein was found to be under daily and seasonal regulation. The observed cyclicity in the amount of PDE10A mRNA persists under constant darkness, is blocked by constant light and is modulated by the lighting regime. It therefore appears to be driven by the master cloc…
The scavenging of nitrogen compounds by clouds and precipitation:
1998
Model predictions of nitric acid scavenging by an air parcel model and a two-dimensional dynamic cloud model with detailed microphysics are compared with corresponding predictions for parameterized microphysics for the same initial conditions. In general the gas uptake proceeds slower in the model with parameterized microphysics than in the model with detailed microphysics and, the larger the drop size, results in a slower mass transfer. This behaviour can be explained by the inverse drop-radius dependency of the mass transfer coefficient and the time delays were a direct result of the microphysical parameterization. With the air parcel model for the scavenging of nitric acid, time delays i…
Synthesis and characterization of nanometric powders of UO2+x, (Th,U)O2+x and (La,U)O2+x
2009
This paper describes a new way of preparing nanometric powders of uranium oxide, to fit the needs of studies on UO{sub 2} oxidation, through the electrochemical reduction of U(VI) into U(IV). These powders can also be doped with radionuclides if necessary. The precipitation of oxides occurs in reducing and anoxic conditions. This original method makes it possible to synthesize nanometric UO{sub 2} powders with a calibrated size, as well as the Th- and La-doped UO{sub 2} powders with a predefined composition. The powder characterization by the X-ray diffraction, X-ray photoelectron spectroscopy and transmission electron Microscopy shows the formation of spherical crystallites of UO{sub 2+x},…
Anodic oxide films on tungsten—I. The influence of anodizing parameters on charging curves and film composition
1980
Abstract The formation of anodic films on tungsten has been studied in 1N solutions of H 2 PO 4 , H 2 SO 4 , HNO 3 , HClO 4 and HCl at different temperatures. The shape of the anodic charging curves depends on the electrolyte composition and on the temperature. The chemical composition of the films is strongly influenced by the working temperature. The first step of the anodization is the formation of a barrier film of amorphous WO 3 . The thickening of the oxide layer occurs on account of the WO 3 dissolution and following precipitation of sparingly soluble oxides on the electrode surface.
Preparation of mixed oxides MNdO3, with M=Cr, Fe. Comparison of several methods
1993
Abstract Different methods for the formation of NdCrO3 and NdFeO3, having the perovskite-like structure, were studied including the ceramic method, simultaneous precipitation of hydroxides and simultaneous crystallization from aqueous solutions of nitrates. Preparation of mixed oxides from hydroxides simultaneously precipitated lowered the temperature and time required for their formation. In the case of NdCrO3 the formation process from hydroxides and nitrates occurred through the chromate, NdCrO4, without intermediate decomposition of the precursor to metal oxides, which lead to the mixed oxide by 600°C.
Synthesis of YAG nanopowder by the co-precipitation method: Influence of pH and study of the reaction mechanisms
2012
International audience; YAG nanopowders with an average grain size of 30 nm have been successfully synthesized by the co-precipitation method using nitrates with precipitant of ammonium hydrogen carbonate. The influence of precipitation conditions such as pH, aging time and calcination temperature on the formation of secondary phases has been studied. The accurate control of pH value at every stage of precipitation process is crucial to avoid the presence of YAM (Yttrium Aluminium Monoclinic, Y4Al2O9) and yttrium oxide (Y2O3) after calcination. The reaction mechanisms have been investigated using different techniques such as infrared spectroscopy, x-ray diffraction and thermal analyses. The…
Synthesis of Multifunctional Inorganic Materials
2018
Abstract Both, novel and older widely and routinely used methods of chemical synthesis fornew multifunctional inorganic (nano) materials with different sizes and morphologies are reviewed and summarized in this chapter. Illustrative examples of micro- and nanoparticle preparations are provided regarding different applications: renewable and sustainable energy harvesting, water splitting and hydrogen generation, fuel and solar cell devices, luminescent materials for white light–emitting diodes and clean environment. We give our perspective on the current status of the topic: methods of colloidal chemistry, coprecipitation, reverse-micelle technique, sol–gel, spray pyrolysis, microwave-assist…