Search results for "Reactive"
showing 10 items of 1469 documents
EPR investigations of polymeric and H2O2 -modified C3N4 -based photocatalysts
2019
The C3N4 -based nanopowders prepared by thermal condensation of melamine (MCN) with subsequent thermal etching (MCN-TE) and H2O2 -treatment were investigated by Q- and X-band EPR spectroscopy in dark and upon in situ UVA or visible-light exposure. Lorentzian signal at g = 2.003, more pronounced in the case of the thermally etched material, dominates EPR spectra of MCN and MCN-TE. More complex spectra were found for H2O2 -treated photocatalysts revealing the presence of signals attributed to the radicals produced via H2O2 interaction with C/N sites in the C3N4 polymeric network. The X-band spectra monitored upon in situ irradiation of the C3N4 -based photocatalysts evidenced the intensity gr…
A High-Resolution Penalization Method for large Mach number Flows in the presence of Obstacles
2009
International audience; A penalization method is applied to model the interaction of large Mach number compressible flows with obstacles. A supplementary term is added to the compressible Navier-Stokes system, seeking to simulate the effect of the Brinkman-penalization technique used in incompressible flow simulations including obstacles. We present a computational study comparing numerical results obtained with this method to theoretical results and to simulations with Fluent software. Our work indicates that this technique can be very promising in applications to complex flows.
Managing information security risks during new technology adoption
2012
Author's version of an article in the journal: Computers and Security. Also available from the publisher at: http://dx.doi.org/10.1016/j.cose.2012.09.001 In the present study, we draw on previous system dynamics research on operational transition and change of vulnerability to investigate the role of incident response capability in controlling the severity of incidents during the adoption of new technology. Toward this end, we build a system dynamics model using the Norwegian Oil and Gas Industry as the context. The Norwegian Oil and Gas Industry has started to adopt new information communication technology to connect its offshore platforms, onshore control centers, and suppliers. In oil co…
No effect of C-reactive protein on early atherosclerosis in LDLR-/- / human C-reactive protein transgenic mice
2008
summaryThe association between increased concentrations of C-reactive protein (CRP) and future cardiovascular events is well established. However, it is currently unclear whether this clinical observation represents an epiphenomenon or whether the pentraxin may actively promote the development of atherosclerosis. Experimental studies with knockout mice with a defect in apolipoprotein E (ApoE-/-) have been used to investigate the role of CRP in atherogenesis, but the results obtained have been contradictory so far. Since knockout mice with a defect in low density lipoprotein receptor (LDLR-/-) may represent a better model of atherogenesis compared to ApoE-/- animals, we undertook experiments…
TGF-beta1 in liver fibrosis: an inducible transgenic mouse model to study liver fibrogenesis.
1999
Transforming growth factor-beta1 (TGF-beta1) is a powerful stimulus for collagen formation in vitro. To determine the in vivo effects of TGF-beta1 on liver fibrogenesis, we generated transgenic mice overexpressing a fusion gene [C-reactive protein (CRP)/TGF-beta1] consisting of the cDNA coding for an activated form of TGF-beta1 under the control of the regulatory elements of the inducible human CRP gene promoter. Two transgenic lines were generated with liver-specific overexpression of mature TGF-beta1. After induction of the acute phase response (15 h) with lipopolysaccharide (100 microgram ip), plasma TGF-beta1 levels reached600 ng/ml in transgenic animals, which is100 times above normal …
Spontaneous hepatic fibrosis in transgenic mice overexpressing PDGF-A.
2008
Platelet derived growth factor (PDGF) plays a central role in repair mechanisms after acute and chronic tissue damage. To further evaluate the role of PDGF-A in liver fibrogenesis in vivo, we generated transgenic mice with hepatocyte-specific overexpression of PDGF-A using the CRP-gene promoter. Transgenic but not wildtype mice showed expression of PDGF-A mRNA in the liver. Hepatic PDGF-A overexpression was accompanied by a significant increase in hepatic procollagen III mRNA expression as well as TGF-beta1 expression. Liver histology showed increased deposition of extracellular matrix in transgenic but not in wildtype mice. PDGF-A-transgenic mice showed positive sinusoidal staining for alp…
Mitochondrial DNA mutations in cancer--from bench to bedside.
2009
Mitochondria are cell organelles mostly known for their production of ATP through oxidative phosphorylation. As suggested over 70 years ago by O. Warburg and recently confirmed with molecular techniques, alterations in respiratory activity and mitochondrial DNA appear to be a common feature of malignant cells. Somatic mtDNA mutations have been reported in many types of cancer cells. MtDNA mutation pattern may enhance the specificity of cancer diagnostics, detection and prediction of tumor growth rate and patients' outcome. Therefore it may be used as a molecular cancer bio-marker. Nevertheless recently published papers list a large number of mitochondrial DNA mutations in many different can…
Human cytochrome P450 reductase can act as a source of endogenous oxidative DNA damage and genetic instability.
2005
Studies with repair-deficient mice and other experiments suggest that oxidative DNA modifications are generated in all types of cells even under physiological conditions and that this type of endogenous DNA damage contributes to spontaneous cancer incidence. However, the cellular sources of reactive oxygen species that are relevant for nuclear oxidative DNA damage are largely unknown. Here, we report that expression of human NADPH-cytochrome P450 reductase (hOR) in cultured V79 Chinese hamster cells gives rise to elevated basal levels of oxidative purine modifications after depletion of glutathione. Also, the basal levels of micronuclei are increased in the hOR-expressing cells, and again t…
Redox regulation of genome stability by effects on gene expression, epigenetic pathways and DNA damage/repair
2015
Reactive oxygen and nitrogen species (e.g. H2O2, nitric oxide) confer redox regulation of essential cellular signaling pathways such as cell differentiation, proliferation, migration and apoptosis. In addition, classical regulation of gene expression or activity, including gene transcription to RNA followed by translation to the protein level, by transcription factors (e.g. NF-κB, HIF-1α) and mRNA binding proteins (e.g. GAPDH, HuR) is subject to redox regulation. This review will give an update of recent discoveries in this field, and specifically highlight the impact of reactive oxygen and nitrogen species on DNA repair systems that contribute to genomic stability. Emphasis will be placed …
Long-Lasting Genomic Instability Following Arsenite Exposure inMammalian Cells: The Role of Reactive Oxygen Species
2011
Previously, we reported that the progeny of mammalian cells, which has been exposed to sodium arsenite for two cell cycles, exhibited chromosomal instability and concurrent DNA hypomethylation, when they were subsequently investigated after two months of subculturing (about 120 cell generations) in arsenite-free medium. In this work, we continued our investigations of the long-lasting arsenite-induced genomic instability by analyzing additional endpoints at several time points during the cell expanded growth. In addition to the progressive increase of aneuploid cells, we also noted micronucleated and multinucleated cells that continued to accumulate up to the 50th cell generation, as well a…