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Results 451 - 500 of 1283
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Takeuchi H - - 2000
p130 was originally identified as an Ins(1,4,5)P(3)-binding protein similar to phospholipase C-delta but lacking any phospholipase activity. In the present study we have further analysed the interactions of p130 with inositol compounds in vitro. To determine which of the potential ligands interacts with p130 in cells, we performed an analysis ...
Chong M W - - 2000
The toxicity of purified blue-green algal toxin, microcystin-LR, on permanent cell lines KB, NIH/3T3, H-4-II-E, HeLa, Vero, Hep G2, Caco-2 and HL-60 was studied. Assessment of cell viability using colorimetric 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays indicated that purified microcystin-LR induced toxic effect on KB and H-4-II-E cell lines after 96 h ...
McClain M S - - 2000
Helicobacter pylori VacA is a secreted toxin that induces multiple structural and functional alterations in eukaryotic cells. Exposure of VacA to either acidic or alkaline pH ('activation') results in structural changes in the protein and a marked enhancement of its cell-vacuolating activity. However, the mechanism by which activation leads to ...
Hoffmann S - - 2000
PURPOSE: To determine the sensitivity of retinal pigment epithelial (RPE) cells to a vascular endothelial growth factor (VEGF) chimeric toxin. METHODS: A targeted toxin was developed using recombinant methods to fuse VEGF165 to the diphtheria toxin (DT) translocation and enzymatic domain (DT390-VEGF165). Human RPE cells, choroidal endothelial cells (CECs), and ...
He D - - 2000
BACKGROUND & AIMS: The mechanism by which Clostridium difficile toxin A causes actin depolymerization and cell rounding involves toxin internalization and subsequent monoglucosylation of the Rho family of proteins. This study explored toxin internalization and effects on mitochondrial function before cell rounding. METHODS: Chinese hamster ovary (CHO) cells were exposed ...
Liu Y Y - - 2000
ADP-ribosylating immunotoxins are generally expressed in Escherichia coli and then refolded in vitro. Because the efficiency of the in vitro refolding process decreases with the number of protein domains and internal disulfide bonds, these immunotoxins have been generally limited to single-chain monovalent structures. We now show that using the hamster ...
McCardell B A - - 2000
Vibrio cholerae strains with all known toxin genes deleted or inactivated still cause diarrhoea in some volunteers, suggesting the presence of an unknown virulence factor or factors. Lysozyme-EDTA treated cells of JBK70, a genetically manipulated cholera toxin negative strain of Vibrio cholerae O1, biotype El Tor, release a factor that ...
Takamori H - - 2000
A human pancreatic cancer cell line, Capan-1, secretes the chemokines interleukin-8 (IL-8) and growth-related oncogene alpha (GROalpha). Capan-1 cells also express the chemokine receptor 2 (CXCR2), which is a Gialpha-protein coupled receptor. Growth of Capan-1 cells was inhibited when anti-IL-8 or anti-GROalpha monoclonal antibody was added into the culture medium. ...
Ji X - - 2000
There are two alleles of the vacuolating cytotoxin gene from Helicobacter pylori, which code for toxins with different cell specificities. By analyzing the phenotypes of natural and artificial chimeras between the two forms of the protein, we have delimited a short stretch of amino acids which determine the cell specificity.
Hughes A K - - 2000
BACKGROUND: Shiga toxin-1 (Stx-1) has been implicated in the pathogenesis of postdiarrheal hemolytic-uremic syndrome (Stx HUS). Endothelial cells had been felt to be the primary renal target of Stx-1; however, recent studies suggest that renal epithelial cells may also be responsive. To further examine this issue, we evaluated the responsiveness ...
Raimondi F - - 2000
Vibrio parahaemolyticus is a marine bacterium known to be a common cause of seafood gastroenteritis worldwide. The thermostable direct hemolysin (TDH) has been proposed to be a major virulence factor of V. parahaemolyticus. TDH causes intestinal fluid secretion as well as cytotoxicity in a variety of cell types. In this ...
Chaddock J A - - 2000
Clostridial neurotoxins potently and specifically inhibit neurotransmitter release in defined cell types by a mechanism that involves cleavage of specific components of the vesicle docking/fusion complex, the SNARE complex. A derivative of the type A neurotoxin from Clostridium botulinum (termed LH(N)/A) that retains catalytic activity can be prepared by proteolysis. ...
Fouillit M - - 2000
It has been well established that Galectin-1 (GAL1), a beta-galactoside-binding protein, regulates the viability of lymphoid cells. However, the signaling pathway governed by the binding of GAL1 to the cell membrane is not understood. As a first step towards the elucidation of GAL1-initiated signaling events leading to a reduced viability ...
Hurná E - - 2000
The induction of micronuclei (MN) in mitotically active cells has been widely used and promoted as a biological marker of exposure to environmental toxins. In our study the effect of zinc on cadmium genotoxicity was investigated in V 79 cells. The results indicate that cadmium chloride exposure for 24 h ...
Fischer W J - - 2000
Mass occurrences of cyanobacteria, due to their inherent capacity for toxin production, specifically of microcystins (MC), have been associated with fish kills worldwide. The uptake of MC-LR and the sequence of pathological and associated biochemical changes was investigated in carp (Cyprinus carpio) in vivo over 72 h. Carp were gavaged ...
Fabczak H - - 2000
The effect of experimental procedures designed to modify an intracellular phosphoinositide signalling pathway, which may be instrumental in the photophobic response of the protozoan ciliate Blepharisma japonicum, has been investigated. To assess this issue, the latency time of the photophobic response and the cell photoresponsiveness have been assayed employing newly ...
Fabbrini M S - - 2000
In this work, we have devised an intracellular immunization strategy for the expression in high amounts of ATF-saporin, a targeted chimeric toxin constituted by the ATF receptor binding domain of human urokinase and the plant ribosome-inactivating protein saporin, which has been shown to be highly cytotoxic to target cells. This ...
Shortt S J - - 2000
The epithelial Madin Darby canine kidney (MDCK) cell line and 17 human cell lines were examined for sensitivity to Clostridium perfringens type D epsilon-toxin. MDCK cells were confirmed as being sensitive to the toxin. In addition, the Caucasian renal leiomyoblastoma (G-402) human cell line was identified as being epsilon-toxin sensitive. ...
Arriagada C - - 2000
Aminochrome was found to be toxic in a mouse-derived neuronal cell line (CNh). The effect was concentration dependent (10-150microM). The issue whether aminochrome toxicity involves glutamate transmission was studied with several glutamate receptors antagonists. Incubation of the cells with aminochrome (150microM) in the presence of 100microM of the AMPA antagonist, ...
John H A - - 2000
To enable direct testing of a range of potential toxins or pathogens that might be involved in grass sickness, equine thoracic sympathetic chain ganglion cell lines were established from primary cell cultures by retroviral-mediated transduction of the temperature-sensitive mutant of the establishment oncogene encoding SV40 large T antigen. Morphological and ...
Bloch K O - - 2000
The aim of our study was to develop a method for selection of subpopulations of insulin producing RINm cells with higher resistance to beta cell toxins. Cells, resistant to streptozotocin (RINmS) and alloxan (RINmA), were obtained by repeated exposure of parental RINm cells to these two toxins, while the defense ...
O'Sullivan G A - - 1999
Botulinum neurotoxin (BoNT) types A and B selectively block exocytosis by cleavage of SNAP-25 and synaptobrevin, respectively; in humans, many months are required for full recovery from the resultant neuromuscular paralysis. To decipher the molecular basis for such prolonged poisoning, intoxication in adreno-chromaffin cells was monitored over 2 months. Exocytosis ...
Clarke B L - - 1999
The effect of incubation temperature and ligand competition was tested for (125)I-ACTH binding to isolated rat lymphocytes. AlphaMSH but not Agouti-like peptide was an effective competitive inhibitor for cell surface binding at 4 degrees C. Cells incubated with (125)I-ACTH at 37 degrees C rapidly associated ligand for 10 min and ...
Gelfanova V - - 1999
The immune response to Haemophilus ducreyi is mediated in part by T cells infiltrating the site of infection. In this study, we show that H. ducreyi antigen preparations inhibited the proliferation of peripheral blood mononuclear cells and primary human T-cell lines. H. ducreyi also inhibited Jurkat T-cell proliferation and induced ...
Sayers N M - - 1999
BACKGROUND: Smoking is a recognized risk factor for the initiation and progression of periodontitis. However, the mechanism by which smoking induces its negative effects on the periodontium is not clear. This study aimed to test the hypothesis that synergy may occur between cotinine and bacterial products isolated from 3 putative ...
Fasano A - - 1999
The application of molecular techniques to the study of bacterial pathogenesis has made possible discoveries that are changing the way scientists view the bacterium-host interaction. Today, research on the molecular basis of the pathogenesis of infective diarrheal diseases of necessity transcends established boundaries between cell biology, bacteriology, intestinal pathophysiology, and ...
Peake P W - - 1999
BACKGROUND: Some individual components of complement are synthesized by the kidney. However, it is not known whether these form functional pathways that are able to mediate more fundamental cellular events. We examined the ability of HK-2 tubular cells to produce an intact alternative pathway of complement and to respond to ...
Ahmed A - - 1999
Killer strains of S. cerevisiae harbor double-stranded RNA viruses and secrete protein toxins that kill virus-free cells. The K1 killer toxin acts on sensitive yeast cells to perturb potassium homeostasis and cause cell death. Here, the toxin is shown to activate the plasma membrane potassium channel of S. cerevisiae, TOK1. ...
Basu I - - 1999
Vibrio cholerae produces a non-membrane damaging cytotoxin (NMDCY), also known as cell rounding factor, which causes rapid rounding of cultured cells like HeLa, CHO and Vero and reportedly elicits enterotoxic activity in the rabbit ileal loop assay. Pursuing the concept that NMDCY might be an accessory factor contributing to the ...
Barth H - - 1999
The Clostridium botulinum C2 toxin ADP-ribosylates monomeric actin, thereby inducing disassembly of actin filaments, alteration of focal adhesions, and rounding of cells. After treatment with C2 toxin, cells stop to proliferate but remain viable for about 2 days. In view of reported correlations between the structure of the actin cytoskeleton ...
Falnes P O - - 1999
Diphtheria toxin enters the cytosol of mammalian cells where it inhibits cellular protein synthesis, leading to cell death. Recently we found that the addition of a signal for N-end-rule-mediated protein degradation to diphtheria toxin substantially reduced its intracellular stability and toxicity. These results prompted us to construct a toxin containing ...
Stein S - - 1999
Conjugates between anti-tetanus F(ab')2 fragments and the (37-72) fragment of the HIV Tat protein were taken up by chromaffin cells, NG108-15 neurohybridoma cells and Rev-2-T-6 lymphoma cells. The uptake could not be inhibited by competition with (37-72)Tat, but was reduced in the presence of metabolic inhibitors or at low temperature. ...
Barth H - - 1999
Clostridium botulinum exoenzyme C3 inactivates the small GTPase Rho by ADP-ribosylation. We used a C3 fusion toxin (C2IN-C3) with high cell accessibility to study the kinetics of Rho inactivation by ADP-ribosylation. In primary cultures of rat astroglial cells and Chinese hamster ovary cells, C2IN-C3 induced the complete ADP-ribosylation of RhoA ...
Lord J M - - 1999
Certain bacteria secrete protein toxins that catalytically modify and disrupt essential processes in mammalian cells, often leading to cell death. As the substrates modified by these toxins are located in the mammalian cell cytosol, a catalytically active toxin polypeptide must reach this compartment in order to act. The toxins bind ...
Lally E T - - 1999
RTX toxins are important virulence factors produced by a wide range of Gram-negative bacteria. They fall into two categories: the hemolysins, which affect a variety of cell types, and the leukotoxins, which are cell-type- and species-specific. These toxins offer interesting models for targeting, insertion and translocation of aqueous proteins into ...
Le Buanec H - - 1999
The human papillomavirus type 16 (HPV-16) E7 oncogenic protein is found in the culture supernatant of SiHa cells, a cervical carcinoma cell line. Extracellular E7 protein, acting as a viral toxin in human immune cells, induces the overproduction of the immune suppressive IFN alpha cytokine by APCs, and inhibits the ...
Borrmann E - - 1999
Ten permanent cell lines were examined for their reaction to the Clostridium novyi alpha toxin. The action of the toxin was determined after 3 days by microscopic examination and the MTT assay. The alpha toxin exhibited the strongest effect on ESH-L cells rather than other cell lines. Vero and SFT-R ...
Pickett C L - - 1999
Cytolethal distending toxins are produced by a small but diverse group of bacterial pathogens. This newly discovered toxin family can cause a variety of mammalian cells to become irreversibly blocked in the G2 phase of the cell cycle. How this novel effect is accomplished is unknown but the study of ...
Mijnes J D - - 1999
The alphaherpesvirus glycoproteins gE and gI form a hetero-oligomeric complex involved in cell-to-cell transmission. The gI-deficient recombinant feline herpesvirus (FHV), FHVdeltagI-LZ, produces plaques that are only 15% the size of those of wild-type FHV. Here, we have complemented FHV(delta)gI-LZ allotopically by expressing intact gI and C-terminally truncated gI derivatives from ...
Sucic J F - - 1999
PACE4 is a member of the eukaryotic subtilisin-like endoprotease family. The expression of human PACE4 in RPE.40 cells (furin-null mutants derived from Chinese hamster ovary K1 cells) resulted in the rescue of a number of wild-type characteristics, including sensitivity to Sindbis virus and the ability to process the low-density-lipoprotein receptor-related ...
Gringorten J L - - 1999
Eight continuous insect cell lines were tested for susceptibility to the delta-endotoxins of several lepidopteran-active strains and cloned-gene products of Bacillus thuringiensis. The assays were performed on cells suspended in agarose gel, which allowed the toxins activated at pH 10.5 to be applied directly in a high-pH buffer without causing ...
Tanaka Y - - 1999
Cholera toxin (CT) can function as a potent adjuvant in the mucosal immune response. However, we have found that treatment of A20-HL murine B lymphoma cells with CT severely inhibits the presentation of ovalbumin (OVA) to cells of the T cell clone 42-6A specific for OVA(323-339)/I-Ad, whereas it does not ...
Navarro-García F - - 1999
We have previously described enteroaggregative Escherichia coli (EAEC) strains that induce cytotoxic effects on T84 cells, ligated rat ileal loops, and human intestine in culture. Such strains secrete a 104-kDa protein termed Pet (for plasmid-encoded toxin). We have also shown previously that the Pet toxin induces rises in short-circuit current ...
Fabbri A - - 1999
Vibrio parahaemolyticus is a marine bacterium known to be the leading cause of seafood gastroenteritis worldwide. A 46-kDa homodimer protein secreted by this microorganism, the thermostable direct hemolysin (TDH), is considered a major virulence factor involved in bacterial pathogenesis since a high percentage of strains of clinical origin are positive ...
Brodsky R A - - 1999
Paroxysmal nocturnal hemoglobinuria (PNH) is a clonal stem cell disorder caused by a somatic mutation of the PIGA gene. The product of this gene is required for the biosynthesis of glycosylphosphatidylinositol (GPI) anchors; therefore, the phenotypic hallmark of PNH cells is an absence or marked deficiency of all GPI-anchored proteins. ...
Steet R - - 1999
In this report, we establish that 3'-azido-3'-deoxythymidine (AZT) treatment of melanoma cells greatly alters the pattern of glycosphingolipid biosynthesis. In SK-MEL-30 cells, synthesis of the gangliosides GM3 and GD3 was significantly inhibited (60% and 50% of control, respectively) and the production of their precursor, lactosylceramide, was stimulated by 2.5-fold. Control ...
Cortes-Bratti X - - 1999
The potent cytolethal distending toxin produced by Haemophilus ducreyi is a putative virulence factor in the pathogenesis of chancroid. We studied its action on eukaryotic cells, with the long-term goal of understanding the pathophysiology of the disease. Intoxication of cultured human epithelial-like cells, human keratinocytes, and hamster fibroblasts was irreversible, ...
el Bayâ A - - 1999
After uptake and retrograde transport pertussis toxin acts by ADP-ribosylating alpha-Gi proteins. We show that uptake via many different receptor proteins followed by retrograde transport and intoxication is not restricted to a particular cell type. The efficiency of cellular intoxication, however, was found to be cell type dependent.
Arab S - - 1998
The pentameric B subunit of verotoxin (VT) mediates the attachment to cell surface globotriaosyl ceramide (Gb3) to facilitate receptor-mediated endocytosis of the toxin. In highly toxin-sensitive tumor cells, the holotoxin and VT1 B subunit is targeted intracellularly to elements of the endoplasmic reticulum (ER)/nuclear membrane. In less sensitive cells, the ...
McDermott C M - - 1998
Cyanobacterial toxins, especially the microcystins (MCYST), are found in eutrophied waters throughout the world. These toxins cause hepatocyte damage by inhibiting protein phosphatases 1 and 2A, resulting in hyperphosphorylation of cytoskeletal proteins. Acute intoxication of animals and humans has been reported following MCYST exposure. Okadaic acid, a marine biotoxin, has ...
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