Search results for "DASES"
showing 10 items of 485 documents
Mechanisms of Increased Vascular Superoxide Production in an Experimental Model of Idiopathic Dilated Cardiomyopathy
2005
Objective— In the present study, we sought to identify mechanisms underlying increased oxidative stress in vascular tissue in an experimental animal model of chronic congestive heart failure (CHF). Methods and Results— Superoxide and nitric oxide (NO) was measured in vessels from cardiomyopathic hamsters (CHF hamsters) and golden Syrian hamsters. We also determined expression of endothelial nitric oxide synthase (NOSIII), the soluble guanylyl cyclase, the cGMP-dependent kinase, and the NADPH oxidase. To analyze the contribution of the renin-angiotensin system to oxidative stress, CHF hamsters were treated with the angiotensin-converting enzyme inhibitor captopril for 200 days (120 mg · kg …
Fetuin-A and Cystatin C Are Endogenous Inhibitors of Human Meprin Metalloproteases
2010
Meprin α and β, zinc metalloproteinases, play significant roles in inflammation, including inflammatory bowel disease (IBD), possibly by activating cytokines, like interleukin 1β, interleukin 18, or tumor growth factor α. Although a number of potential activators for meprins are known, no endogenous inhibitors have been identified. In this work, we analyzed the inhibitory potential of human plasma and identified bovine fetuin-A as an endogenous meprin inhibitor with a K(i) (inhibition constant) of 4.2 × 10(-5) M for meprin α and a K(i) of 1.1 × 10(-6) M meprin β. This correlated with data obtained for a fetuin-A homologue from carp (nephrosin inhibitor) that revealed a potent meprin α and β…
Silicateins, the major biosilica forming enzymes present in demosponges: protein analysis and phylogenetic relationship.
2007
Silicateins are enzymes, which are restricted to sponges (phylum Porifera), that mediate the catalytic formation of biosilica from monomeric silicon compounds. The silicatein protein is compartmented in the sponges in the axial filaments which reside in the axial canals of the siliceous spicules. In the present study silicatein has been isolated from the freshwater sponge Lubomirskia baicalensis where it occurs in isoforms with sizes of 23 kDa, 24 kDa and 26 kDa. Since the larger protein is glycosylated we posit that it is a processed form of one of the smaller size forms. The silicatein isoforms are post-translationally modified by phosphorylation; at least four isoforms exist with pI's of…
Altered morphological and electrophysiological properties of Cajal-Retzius cells in cerebral cortex of embryonic Presenilin-1 knockout mice
2004
Mutations of Presenilin-1 are the major cause of familial Alzheimer's disease. Presenilin-1 knockout (PS1-/-) mice develop severe cortical dysplasia related to human type 2 lissencephaly. This overmigration syndrome has been attributed to the premature loss of Cajal-Retzius cells (CRcs), pioneer neurons required for the termination of radial neuronal migration. To elucidate the potential cellular mechanisms responsible for this premature neuronal loss, we investigated the morphological and electrophysiological properties of visually identified CRcs of wild-type (WT) and PS1-/- mouse brains at embryonic day 16.5. The density of CRcs was substantially reduced in the cerebral cortex of PS1-/-.…
Autocatalytic cleavage of Clostridium difficile toxin B.
2007
Clostridium difficile, the causative agent of nosocomial antibiotic-associated diarrhoea and pseudomembranous colitis, possesses two main virulence factors: the large clostridial cytotoxins A and B. It has been proposed that toxin B is cleaved by a cytosolic factor of the eukaryotic target cell during its cellular uptake. Here we report that cleavage of not only toxin B, but also all other large clostridial cytotoxins, is an autocatalytic process dependent on host cytosolic inositolphosphate cofactors. A covalent inhibitor of aspartate proteases, 1,2-epoxy-3-(p-nitrophenoxy)propane, completely blocked toxin B function on cultured cells and was used to identify its catalytically active prote…
Indicaxanthin inhibits NADPH oxidase (NOX)-1 activation and NF-κB-dependent release of inflammatory mediators and prevents the increase of epithelial…
2014
Dietary redox-active/antioxidant phytochemicals may help control or mitigate the inflammatory response in chronic inflammatory bowel disease (IBD). In the present study, the anti-inflammatory activity of indicaxanthin (Ind), a pigment from the edible fruit of cactus pear (Opuntia ficus-indica, L.), was shown in an IBD model consisting of a human intestinal epithelial cell line (Caco-2 cells) stimulated by IL-1β, a cytokine known to play a major role in the initiation and amplification of inflammatory activity in IBD. The exposure of Caco-2 cells to IL-1β brought about the activation of NADPH oxidase (NOX-1) and the generation of reactive oxygen species (ROS) to activate intracellular signal…
Evidence for a selective and electroneutral K+/H+-exchange in Saccharomyces cerevisiae using plasma membrane vesicles
1996
The existence of a K+/H+ transport system in plasma membrane vesicles from Saccharomyces cerevisiae is demonstrated using fluorimetric monitoring of proton fluxes across vesicles (ACMA fluorescence quenching). Plasma membrane vesicles used for this study were obtained by a purification/reconstitution protocol based on differential and discontinuous sucrose gradient centrifugations followed by an octylglucoside dilution/gel filtration procedure. This method produces a high percentage of tightly-sealed inside-out plasma membrane vesicles. In these vesicles, the K+/H+ transport system, which is able to catalyse both K+ influx and efflux, is mainly driven by the K+ transmembrane gradient and ca…
Inhibitors of Rho-kinase modulate amyloid-β (Aβ) secretion but lack selectivity for Aβ42
2005
Certain non-steroidal anti-inflammatory drugs (NSAIDs) preferentially inhibit production of the amyloidogenic Abeta42 peptide, presumably by direct modulation of gamma-secretase activity. A recent report indicated that NSAIDs could reduce Abeta42 by inhibition of the small GTPase Rho, and a single inhibitor of Rho kinase (ROCK) mimicked the effects of Abeta42-lowering NSAIDs. To investigate whether Abeta42 reduction is a common property of ROCK inhibitors, we tested commercially available compounds in cell lines that were previously used to demonstrate the Abeta42-lowering activity of NSAIDs. Surprisingly, we found that two ROCK inhibitors reduced total Abeta secretion in a dose-dependent m…
α-Secretase Activity of the Disintegrin Metalloprotease ADAM 10: Influences of Domain Structure
2001
Disintegrin metalloproteases from different organisms form the ADAM (a disintegrin and metalloprotease) family. All members display a common domain organization and possess four potential functions: proteolysis, cell adhesion, cell fusion, and cell signaling. Members of the ADAM family are responsible for the proteolytic cleavage of transmembrane proteins and release of their extracellular domain. The proteolytic process is referred to as ectodomain shedding, which is activated by phorbol esters and inhibited by hydroxamic acid-based inhibitors. We have shown that the disintegrin metalloprotease ADAM 10 has both constitutive and regulated alpha-secretase activity. Expression of a dominant n…
Cre-mediated cell ablation contests mast cell contribution in models of antibody- and T cell-mediated autoimmunity.
2011
SummaryImmunological functions of mast cells remain poorly understood. Studies in Kit mutant mice suggest key roles for mast cells in certain antibody- and T cell-mediated autoimmune diseases. However, Kit mutations affect multiple cell types of both immune and nonimmune origin. Here, we show that targeted insertion of Cre-recombinase into the mast cell carboxypeptidase A3 locus deleted mast cells in connective and mucosal tissues by a genotoxic Trp53-dependent mechanism. Cre-mediated mast cell eradication (Cre-Master) mice had, with the exception of a lack of mast cells and reduced basophils, a normal immune system. Cre-Master mice were refractory to IgE-mediated anaphylaxis, and this defe…