Search results for "toxin"
showing 10 items of 1434 documents
Major histocompatibility complex class II binding site for streptococcal pyrogenic (erythrogenic) toxin A.
1994
Streptococcal pyrogenic exotoxin A (SPEA) is an important pathogenicity factor of group A streptococci. It is a member of the family of „superantigens” produced by Staphylococcus aureus and Streptococcus pyogenes and its T lymphocyte stimulating activity is involved into the pathogenesis of certain diseases caused by pyogenic streptococci. In this study we have produced and characterized recombinant SPEA molecules in Escherichia coli. These molecules are indistinguishable from natural SPEA in both T cell stimulatory and HLA class II binding activities. Human class II molecules are more efficient than mouse class II molecules in presenting SPEA to T cells. In binding tests to major histocomp…
Identification of group A porcine rotavirus strains bearing a novel VP4 (P) genotype in Italian swine herds.
2007
ABSTRACT The VP4 gene of a G5 Italian porcine rotavirus strain, 344/04-1, was nontypeable by PCR genotyping. The amino acid sequence of the full-length VP4 protein had low identity (≤76.6%) with the homologous sequences of representative strains of the remaining P genotypes, providing evidence for a novel P genotype.
Characterization of Shiga toxin-producing Escherichia coli O157:H7 isolated in Italy and in France
2002
ABSTRACT Twenty-one Escherichia coli O157:H7 strains isolated in northern Italy from sporadic cases of hemolytic-uremic syndrome and from cattle and food were characterized by virulence gene analysis, pulsed-field gel electrophoresis (PFGE) of Xba I-digested DNA, enterobacterial repetitive intergenic consensus (ERIC) sequence-based PCR (ERIC-PCR), and antibiotic resistance patterns and compared to 18 strains isolated in France from human cases of diarrhea, cattle, and the environment. Strains isolated in Sicily (southern Italy) from a local farm (one strain) and from calves just imported from France (11 strains) and Spain (six strains) were also typed. Whereas the eae and hlyA genes were al…
Recombinant epidermolytic (exfoliative) toxin A of Staphylococcus aureus is not a superantigen
1992
The epidermolytic (exfoliative) toxins produced by Staphylococcus aureus cause epidermolysis and skin blistering. In addition, they have been implicated to belong to the group of T lymphocyte stimulating molecules known as "superantigens". Here we show that recombinant epidermolytic toxin A produced in S. aureus is not mitogenic for human and murine T lymphocytes. We discuss the possibility that minute contaminations of highly mitogenic exoproteins may cause the mitogenicity in several proteins that are reported to be superantigens.
Staphylococcus aureus α-Toxin’s Close Contacts Ensure the Kill
2018
The membrane pore-forming α-toxin is an important virulence factor of Staphylococcus aureus. Target cells can remove pores from their surface, but recent work shows that α-toxin may undermine this self-defense by clinging to epithelial cell junctions. The findings could lead to the development of novel remedies against S. aureus infections.
A guide to the use of pore-forming toxins for controlled permeabilization of cell membranes
1993
Depending on the size of the pores one wishes to produce in plasma membranes, the choice will probably fall on one of the three toxins discussed above. S. aureus alpha-toxin should be tried first when pores of 1-1.5 nm diameter are required. This is generally the case when Ca2+ and nucleotide dependence of a given process is being studied. If alpha-toxin does not work, this is probably due to the fact that the toxin either does not produce pores, or that the pores are too small. In this case, high concentrations of alpha-toxin should be tried. If this still does not work, we recommend the use of HlyA. When very large pores are to be created, e.g. for introduction of antibodies into the cell…
Biosensing of microcystins in water samples; recent advances
2020
Safety and quality of water are significant matters for agriculture, animals and human health. Microcystins, as secondary metabolite of cyanobacteria (blue-green algae) and cyclic heptapeptide cyanotoxin, are one of the main marine toxins in continental aquatic ecosystems. More than 100 microcystins have been identified, of which MC-LR is the most important type due to its high toxicity and common detection in the environment. Climate change is an impressive factor with effects on cyanobacterial blooms as source of microcystins. The presence of this cyanotoxin in freshwater, drinking water, water reservoir supplies and food (vegetable, fish and shellfish) has created a common phenomenon in …
Cyanobacteria and their metabolites in mono- and polidominant shallow eutrophic temperate lakes
2022
Monodominant (one species dominates) or polidominant (multiple species dominate) cyanobacterial blooms are pronounced in productive freshwater ecosystems and pose a potential threat to the biota due to the synthesis of toxins. Seasonal changes in cyanobacteria species and cyanometabolites composition were studied in two shallow temperate eutrophic lakes. Data on cyanobacteria biomass and diversity of dominant species in the lakes were combined with chemical and molecular analyses of fifteen potentially toxin-producing cyanobacteria species (248 isolates from the lakes). Anatoxin-a, saxitoxin, microcystins and other non-ribosomal peptides formed the diverse profiles in monodominant (Planktot…
Stimulation of hippocampal acetylcholine release by hyperforin, a constituent of St. John’s Wort
2004
Abstract Extracts of the medicinal plant St. John’s Wort ( Hypericum perforatum ) are widely used in the therapy of affective disorders and have been reported to exert antidepressant, anxiolytic, and cognitive effects in experimental and clinical studies. We here report that hyperforin, the major active constituent of the extract, increases the release of acetylcholine from rat hippocampus in vivo as determined by microdialysis. Hippocampal acetylcholine levels were increased by 50–100% following the systemic administration of pure hyperforin at doses of 1 and 10 mg/kg. The effect was almost completely suppressed by local perfusion with calcium-free buffer or with tetrodotoxin (1 μM). We co…
Pharmacological activity of C10-substituted analogs of the high-affinity kainate receptor agonist dysiherbaine
2009
Kainate receptor antagonists have potential as therapeutic agents in a number of neuropathologies. Synthetic modification of the convulsant marine toxin neodysiherbaine A (NDH) previously yielded molecules with a diverse set of pharmacological actions on kainate receptors. Here we characterize three new synthetic analogs of NDH that contain substituents at the C10 position in the pyran ring of the marine toxin. The analogs exhibited high-affinity binding to the GluK1 (GluR5) subunit and lower affinity binding to GluK2 (GluR6) and GluK3 (GluR7) subunits in radioligand displacement assays with recombinant kainate and AMPA receptors. As well, the natural toxin NDH exhibited approximately 100-f…