Search results for "toxin"

Monitoring of Bacillus Thuringiensis Cry3Aa Toxin Pore Formation using Artificial Bilayer Array with Fused Brush Border Membrane Vesicles from Colora…

2017

Study of the bacillus thuringiensis Cry1Ia protein oligomerization promoted by midgut brush border membrane vesicles of lepidopteran and coleopteran …

2020

Bacillus thuringiensis (Bt) produces insecticidal proteins that are either secreted during the vegetative growth phase or accumulated in the crystal inclusions (Cry proteins) in the stationary phase. Cry1I proteins share the three domain (3D) structure typical of crystal proteins but are secreted to the media early in the stationary growth phase. In the generally accepted mode of action of 3D Cry proteins (sequential binding model), the formation of an oligomer (tetramer) has been described as a major step, necessary for pore formation and subsequent toxicity. To know if this could be extended to Cry1I proteins, the formation of Cry1Ia oligomers was studied by Western blot, after the incuba…

Staphylococcal alpha-toxin provokes neutrophil-dependent cardiac dysfunction: role of ICAM-1 and cys-leukotrienes.

2002

The role of polymorphonuclear neutrophils (PMN) in septic myocardial dysfunction is presently unknown. Staphylococcus aureus infections are frequently associated with septic sequelae. Therefore, we perfused isolated rat hearts with low doses of α-toxin, the major staphylococcal exotoxin, followed by application of human PMN, N-formyl-methionyl-leucyl-phenylalanine, and arachidonic acid. In contrast to sham-perfused hearts (no α-toxin), a rise in coronary perfusion pressure (CPP) and a reduction of contractile function were noted, and cardiac expression of intercellular adhesion molecule (ICAM)-1 was detected by immunohistochemical methods and real-time PCR. Histological analysis and myelope…

Tetracycline inhibits the nitric oxide synthase activity induced by endotoxin in cultured murine macrophages

1998

Here we investigate the effects of tetracycline base and of a semi-synthetic tetracycline derivative, doxycycline, on the induction of inducible nitric oxide synthase and, hence, on the production of nitric oxide (NO) by lipopolysaccharide in J774 macrophage cultured in vitro. The treatment of J774 line with tetracycline base (6.25-250 microM) or doxycycline (5-50 microM) dose-dependently decreased the lipopolysaccharide-stimulated (1 microg/ml) inducible NO synthase activity and, consequently, nitrite formation. For instance, the inhibition was 70% for tetracycline base at 250 microM and 68% for doxycycline at 50 microM. The inhibitory effect of tetracyclines was due neither to a reduction…

Human endothelial cell-based assay for endotoxin as sensitive as the conventional Limulus Amebocyte Lysate assay

2014

AbstractEndotoxin, also known as lipopolysaccharide (LPS) produced by bacteria can be present in any liquid or on any biomaterial even if the material is sterile. Endotoxin in mammals can cause fever, inflammation, cell and tissue damage and irreversible septic shock and death. In the body, endothelial cells making up the blood vasculature and endothelial cells in vitro rapidly react to minute amounts of endotoxin resulting in a rapid induction of the cell adhesion molecule E-selectin. In this study we have used immunofluorescent staining to evaluate the expression of E-selectin on human microvascular endothelial cells from the skin (HDMEC) and human umbilical vein endothelial cells (HUVEC)…

Effects of Escherichia coli hemolysin on human monocytes. Cytocidal action and stimulation of interleukin 1 release.

1990

Abstract This study reports on the potent cytocidal and interleukin-1 releasing properties of Escherichia coli hemolysin (ECH) on human monocytes. Nanomolar concentrations of purified ECH (250-2,000 ng/ml) caused rapid and irreversible depletion of cellular ATP to levels below 20% of controls within 60 min. Subcytocidal doses (10-200 ng/ml) of ECH induced rapid release within 60-120 min of large amounts of interleukin 1 beta (IL-1 beta) from cultured monocytes. IL-1 beta release occurred in the presence of actinomycin D and cycloheximide, and was thus probably due to processing and export of intracellular IL-1 beta precursor. Incubation of toxin-producing E. coli at ratios of only 0.3-3 col…

New functional ligands for ficolin-3 among lipopolysaccharides of Hafnia alvei.

2011

Ficolin-1 (M), ficolin-2 (L), ficolin-3 (H) and mannan-binding lectin (MBL) activate the complement system and have opsonic activity. The specificity of ficolin-3 is poorly characterized and currently limited to a few ligands only. We present new specific targets for human ficolin-3, identified among lipopolysaccharides (LPSs, endotoxin) of Hafnia alvei. The interaction was restricted to LPSs of four strains: 23, Polish Collection of Microorganisms (PCM) 1200, PCM 1203 and PCM 1205 and limited to their O-specific polysaccharides (O-specific PSs) composed of different numbers of oligosaccharide (OS) repeating units (RUs). Moreover, these LPS/ficolin-3 complexes activated the lectin pathway o…

Identification from a Positional Scanning Peptoid Library of in Vivo Active Compounds That Neutralize Bacterial Endotoxins

2005

4 pages, 3 figures, 1 table.-- PMID: 15715495 [PubMed].-- Printed version published Feb 24, 2005.-- Supporting information available at: http://pubs.acs.org/doi/suppl/10.1021/jm040834i

Stimulation of monokine production by lipoteichoic acids

1991

Lipoteichoic acids (LTAs) isolated from bacterial species, including Staphylococcus aureus, Streptococcus pyogenes A, Enterococcus faecalis, Streptococcus pneumoniae, and Listeria monocytogenes, were tested for their ability to stimulate the production of interleukin-1 beta (IL-1 beta), IL-6, and tumor necrosis factor alpha in cultured human monocytes. LTAs from S. aureus and S. pneumoniae failed to induce monokine production when applied in the concentration range of 0.05 to 5.0 micrograms/ml. However, LTAs from several enterococcal species (0.5 to 5 micrograms/ml) induced the release of all three monokines at levels similar to those observed after lipopolysaccharide stimulation. The kinet…

Interaction of TLR2 and TLR4 ligands with the N-terminal domain of Gp96 amplifies innate and adaptive immune responses.

2006

Activation of dendritic cells by ligands for Toll-like receptors (TLR) is a crucial event in the initiation of innate and adaptive immune responses. Several classes of TLR ligands have been identified that interact with distinct members of the TLR-family. TLR4 ligands include lipopolysaccharide derived from different Gram-negative bacteria and viral proteins. Recent reports have demonstrated the TLR-mediated activation of dendritic cells by heat shock proteins (HSPs). However, doubts were raised as to what extent this effect was due to lipopolysaccharide contaminations of the HSP preparations. We re-examined this phenomenon using Gp96 or its N-terminal domain, nominally endotoxin-free (0.5 …