Toxins A/B Dotaz Zobrazit nápovědu
Toxins are produced by bacteria, plants and animals for defense or for predation. Most of the toxins specifically affect the mammalian nervous system by interfering with the transmission of nerve impulses, and such toxins have the potential for misuse by the military or terrorist organizations. This review discusses the origin, structure, toxicity and symptoms, transmission, mechanism(s) of action, symptomatic treatment of the most important toxins and venoms derived from fungi, plants, marine animals, and microorganisms, along with their potential for use in bioweapons and/or biocrime. Fungal trichothecenes and aflatoxins are potent inhibitors of protein synthesis in most eukaryotes and have been used as biological warfare agents. Ricin and abrin are plant-derived toxins that prevent the elongation of polypeptide chains. Saxitoxin, anatoxin, and tetrodotoxin are marine-derived toxins that bind to sodium channels in nerve and muscle tissue and cause muscle paralysis. Most bacterial toxins, such as botulinum and Shiga affect either the nervous system (neurotoxins) or damage cell membranes. Batrachotoxins, which are secreted by poison-dart frogs are extremely potent cardiotoxic and neurotoxic steroidal alkaloids. The aim of this review is to provide basic information to enable further understanding of these toxins and their potential military uses.
- MeSH
- abrin chemie otrava škodlivé účinky MeSH
- aflatoxiny chemie otrava škodlivé účinky MeSH
- bakteriální toxiny otrava MeSH
- batrachotoxiny chemie otrava škodlivé účinky MeSH
- biologické bojové látky * MeSH
- biologické toxiny * otrava škodlivé účinky MeSH
- botulotoxiny chemie otrava škodlivé účinky MeSH
- lidé MeSH
- mořské toxiny otrava MeSH
- mykotoxiny otrava škodlivé účinky MeSH
- otrava * prevence a kontrola terapie MeSH
- ricin chemie otrava škodlivé účinky MeSH
- saxitoxin chemie otrava škodlivé účinky MeSH
- shiga toxiny chemie otrava škodlivé účinky MeSH
- T-2 toxin chemie otrava škodlivé účinky MeSH
- tetrodotoxin chemie otrava škodlivé účinky MeSH
- toxoidy otrava škodlivé účinky MeSH
- živočišné jedy otrava škodlivé účinky MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- práce podpořená grantem MeSH
- přehledy MeSH
Insight into how environmental change determines the production and distribution of cyanobacterial toxins is necessary for risk assessment. Management guidelines currently focus on hepatotoxins (microcystins). Increasing attention is given to other classes, such as neurotoxins (e.g., anatoxin-a) and cytotoxins (e.g., cylindrospermopsin) due to their potency. Most studies examine the relationship between individual toxin variants and environmental factors, such as nutrients, temperature and light. In summer 2015, we collected samples across Europe to investigate the effect of nutrient and temperature gradients on the variability of toxin production at a continental scale. Direct and indirect effects of temperature were the main drivers of the spatial distribution in the toxins produced by the cyanobacterial community, the toxin concentrations and toxin quota. Generalized linear models showed that a Toxin Diversity Index (TDI) increased with latitude, while it decreased with water stability. Increases in TDI were explained through a significant increase in toxin variants such as MC-YR, anatoxin and cylindrospermopsin, accompanied by a decreasing presence of MC-LR. While global warming continues, the direct and indirect effects of increased lake temperatures will drive changes in the distribution of cyanobacterial toxins in Europe, potentially promoting selection of a few highly toxic species or strains.
- MeSH
- bakteriální toxiny analýza MeSH
- jezera mikrobiologie MeSH
- klimatické změny MeSH
- látky znečišťující vodu analýza MeSH
- mikrocystiny analýza MeSH
- monitorování životního prostředí MeSH
- sinice * MeSH
- teplota MeSH
- tropany analýza MeSH
- uracil analogy a deriváty analýza MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Geografické názvy
- Evropa MeSH
Bacterial toxins share the ability to enter host cells to target various intracellular proteins and to modulate host immune responses. Over the last 20 years, toxins and their mutated variants, as well as live attenuated bacteria, have been exploited for vaccination and immunotherapy of various infectious, malignant and autoimmune diseases. The ability of Bordetella pertussis adenylate cyclase toxin to translocate its adenylate cyclase domain across the host cell membrane, as well as the pathways of intracellular trafficking of Bacillus anthracis lethal and edema toxins, Shigella dysenteriae shiga toxin or Escherichia coli shiga-like toxin, have been repeatedly exploited for the delivery of antigenic epitopes into host cells and for stimulation of antigen-specific T cell responses. Similarly, E. coli α-hemolysin, or effector proteins of Yersinia and Salmonella secreted by the type III secretion systems, were used to facilitate the delivery of fused heterologous proteins or peptides for antigenic presentation. Vibrio cholerae cholera toxin, E. coli heat-labile enterotoxin, B. pertussis pertussis toxin or the Cry1A protein of Bacillus thuringiensis have shown a great potential to act as adjuvants and to stimulate mucosal as well as systemic immune responses. The immunotherapeutic potential of some toxins, like Clostridium perfringens perfringolysin O, Streptococcus intermedius intermedilysin, or Streptococcus pneumoniae pneumolysin needs to be evaluated further. The Bordetella adenylate cyclase toxoid used as a vaccine delivery tool, or Corynebacterium diphtheriae diphtheria toxin and Pseudomonas aeruginosa exotoxin A-based immunotoxins, are currently in various phases of clinical trials for cancer immunotherapy, as are some antigen-delivering Salmonella and Listeria monocytogenes strains.
- MeSH
- antigeny aplikace a dávkování MeSH
- bakteriální toxiny imunologie MeSH
- imunoterapie MeSH
- lidé MeSH
- nádory terapie MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- přehledy MeSH
Zentralblatt für Bakteriologie ISSN 0941-018X Suppl. 23
XIV, 513 s. : il.
- MeSH
- mikrobiologie MeSH
- toxikologie MeSH
- Konspekt
- Mikrobiologie
- NLK Obory
- mikrobiologie
- toxikologie
There is a wide variety of ion channel types with various types of blockers, making research in this field very complicated. To reduce this complexity, it is essential to study ion channels and their blockers independently. Scorpion toxins, a major class of blockers, are charged short peptides with high affinities for potassium channels. Their high selectivity and inhibitory properties make them an important pharmacological tool for treating autoimmune or nervous system disorders. Scorpion toxins typically have highly charged surfaces and-like other proteins-an intrinsic ability to bind ions (Friedman J Phys Chem B 115(29):9213-9223, 1996; Baldwin Biophys J 71(4):2056-2063, 1996; Vrbka et al. Proc Natl Acad Sci USA 103(42):15440-15444, 2006a; Vrbka et al. J Phys Chem B 110(13):7036-43, 2006b). Thus, their effects on potassium channels are usually investigated in various ionic solutions. In this work, computer simulations of protein structures were performed to analyze the structural properties of the key residues (i.e., those that are presumably involved in contact with the surfaces of the ion channels) of 12 scorpion toxins. The presence of the two most physiologically abundant cations, Na(+) and K(+), was considered. The results indicated that the ion-binding properties of the toxin residues vary. Overall, all of the investigated toxins had more stable structures in ionic solutions than in water. We found that both the number and length of elements in the secondary structure varied depending on the ionic solution used (i.e., in the presence of NaCl or KCl). This study revealed that the ionic solution should be chosen carefully before performing experiments on these toxins. Similarly, the influence of these ions should be taken into consideration in the design of toxin-based pharmaceuticals.
A total of 17 strains of Stachybotrys atra isolated in Hungary and Czechoslovakia were cultured on Sabouraud agar, and the toxins produced by them were chemically analyzed by gas-liquid chromatography, high-pressure liquid chromatography, and mass spectroscopy. Furthermore, brine shrimp (Artemia salina) bioassay was used for the determination of toxicity of the compounds examined. Macrocyclic trichothecenes (satratoxins H and G, roridin E, and verrucarin J as well as two other unidentified macrocyclic trichothecenes) were found in all of the cultures tested. The identities of satratoxins H and G, roridin E, and verrucarin J were qualitatively determined by high-pressure liquid chromatography and gas-liquid chromatography. The ratio of satratoxins H and G and roridin E was found to be similar in each of the strains tested, but the amount of verrucarin J found was different in each of them. One of the unidentified macrocyclic trichothecenes was equivalent to the compound isolated by Harrach et al. (Harrach et al., Appl. Environ. Microbiol. 41:1428-1433, 1981). The other one proved to be a newly isolated macrocyclic trichothecene toxin. Stachybotryotoxicosis, one of the oldest mycotoxicoses known, and a serious problem in Middle Europe (Gy. Danko, Magy. Allatorv. Lapja 31:226-232, 1976), is believed to be caused by macrocyclic trichothecene toxins produced by Stachybotrys atra (R. M. Eppley, in Rodricks et al., ed., Mycotoxins in Human and Animal Health, p. 285-293, 1977). Forty years ago, the death of animals in the Soviet Union was associated with this fungus (C. U. Ruhliada, in Proceedings of the All-Union Sci. and Tech. Conf., p. 47-51, 1980).(ABSTRACT TRUNCATED AT 250 WORDS)
- MeSH
- mitosporické houby metabolismus MeSH
- seskviterpeny izolace a purifikace MeSH
- Stachybotrys metabolismus MeSH
- trichotheceny izolace a purifikace toxicita MeSH
- zvířata MeSH
- Check Tag
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Československo MeSH
- Maďarsko MeSH
Staphylococcus aureus je významný oportunní patogen a častý původce bakteriálních nozokomiálních nákaz.Patogenní vlastnosti této bakterie jsou často kódovány mobilními genetickými elementy, jako jsou např. plazmi-dy. Na plazmidu se nachází i gen etb pro exfoliativní toxin B (ETB), který je příčinou puchýřnatého onemocnění(bulózní impetigo), jehož generalizovaná a život ohrožující forma se označuje jako stafylokokový syndrom opařené kůže. U pěti etb-pozitivních plazmidů, izolovaných během let 1999–2015 z kmenů S. aureus pocházejícíchz českých nemocnic, byla provedena srovnávací sekvenční analýza. Bylo zjištěno, že velká většina z nich sdílírozsáhlou oblast sekvence DNA, která zahrnuje typické geny virulence, avšak obsahují i variabilní úseky umož-ňující jejich diferenciaci. Přestože se dosud předpokládalo, že jsou ETB plazmidy relativně uniformní, byl izolo-ván a popsán nový typ, který s ostatními ETB plazmidy vykazuje jen minimální sekvenční shodu. Nese navíc geny pro horizontální přenos konjugací a nové varianty genů pro faktory virulence včetně etb, čímž reprezentuje zcela novou linii plazmidů kódujících exfoliatin B.
Staphylococcus aureus is an important opportunistic pathogen and a common cause of bacterial nosocomialinfections. Pathogenic properties of this bacterium are often encoded by mobile genetic elements, such as plas-mids. Plasmids also carry the etb gene encoding exfoliative toxin B(ETB), which is the cause of ablistering disease(bullous impetigo)whose generalized and life-threatening form is known as staphylococcal scalded skin syn-drome. Comparative sequence analysis was conducted to study five etb-positive plasmids, isolated from S. aureusstrains from Czech hospitals between 1999 and 2015. They were found to share a large part of the DNA sequencecomprising typical virulence genes. However, they also contain variable fragments, which help us to differentiatebetween them. Although ETB plasmids were previously assumed to be relatively uniform, a new type showingminimal sequence similarity to other ETB plasmids was isolated and described. Moreover, it carries genes forhorizontal transfer by conjugation as well as new variants of genes for virulence factors, including etb, and assuch it represents a completely new lineage of exfoliative toxin B-encoding plasmids.
