4,098 research outputs found
TRADE REMEDY ACTIONS IN NAFTA AGRICULTURE AND AGRI-FOOD INDUSTRIES
International Relations/Trade,
Sensitive superoxide detection in vascular cells by the new chemiluminescence dye L-012
The detection superoxide production in vascular cells is usually limited by a low sensitivity of available assays, We tested the applicability of the luminol derivate L-012 {[}8-amino-5-chloro-7-phenylpyridol{[}3,4-d]pyridazine-l,4(2H,3H)dione] to measure superoxide production in cultured endothelial cells (human umbilical vein endothelial cells) and rat aortic segments. Following stimulation with the protein kinase stimulator phorbol 12-myristate 13-acetate (PMA, 1 mu M) there was an 2,8-fold increase of L-012 chemiluminescence, whereas incubation with angiotensin II (100 nM) did not result in a measurable increase. Addition of vanadate (100 mu M) considerably increased the chemiluminescence (up to 17-fold) after PMA and made possible the detection of an enhanced superoxide production after stimulation with angiotensin II (by 1.7-fold). This was due to a similar to 9-fold increase in signal intensity of L-012 in the presence of vanadate, Prolonged incubation with vanadate also led to a tyrosine phosphorylation-dependent increase in superoxide formation which was predominantly produced by an NAD(P)H oxidase. Short-Term vanadate-enhanced L-012 chemiluminescence represents a highly sensitive assay making it possible to detect small changes of superoxide formation in intact vascular cells. Copyright(C) 1999 S. Karger AG. Basel
Wavelet Image Restoration Using Multifractal Priors
Bayesian image restoration has had a long history of successful application
but one of the limitations that has prevented more widespread use is that the
methods are generally computationally intensive. The authors recently addressed
this issue by developing a method that performs the image enhancement in an
orthogonal space (Fourier space in that case) which effectively transforms the
problem from a large multivariate optimization problem to a set of smaller
independent univariate optimization problems. The current paper extends these
methods to analysis in another orthogonal basis, wavelets. While still
providing the computational efficiency obtained with the original method in
Fourier space, this extension allows more flexibility in adapting to local
properties of the images, as well as capitalizing on the long history of
developments for wavelet shrinkage methods. In addition, wavelet methods,
including empirical Bayes specific methods, have recently been developed to
effectively capture multifractal properties of images. An extension of these
methods is utilized to enhance the recovery of textural characteristics of the
underlying image. These enhancements should be beneficial in characterizing
textural differences such as those occurring in medical images of diseased and
healthy tissues. The Bayesian framework defined in the space of wavelets
provides a flexible model that is easily extended to a variety of imaging
contexts.Comment: 19 pages, 4 figure
Crucial role of local peroxynitrite formation in neutrophil-induced endothelial cell activation
Introduction and methods: The reaction of superoxide anions and NO not only results in a decreased availability of NO, but also leads to the formation of peroxynitrite, the role of which in the cardiovascular system is still discussed controversially. In cultured human endothelial cells, we studied whether there is a significant interaction between endothelial NO and neutrophil-derived superoxide anions in terms of endothelial peroxynitrite formation. We particularly studied whether a significantly higher redox-stress can be found in those endothelial cells directly adjacent to an activated neutrophil. Results: A considerable part of the 2,7-dihydrodichlorofluoresceine signal in endothelial cells was due to oxidation by peroxynitrite. Providing superoxide radicals by enzymatic source or by the neutrophil respiratory burst increased the fluorescence, which was attenuated by blockade of endothelial NO-synthase, suggesting that peroxynitrite was formed from neutrophil- or extracellular enzyme-derived superoxide and endothelial NO. Considerably higher fluorescence intensity was observed in endothelial cells in direct neighborhood to a neutrophil. This was particularly pronounced in the presence of a NO-donor and was accompanied by a strong activation of NF-ÎşB and increased expression of E-selectin in these cells. Conclusion: Endothelial cells adjacent to neutrophils may have elevated levels of peroxynitrite that result in an increased expression of adhesion molecules. Such cells might represent a preferential site for adhesion and migration of additional neutrophils when simultaneously high concentrations of NO and neutrophil-derived superoxide are present
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