Sample records for heat labile toxin

  1. In vitro formation of hybrid toxins between subunits of Escherichia coli heat-labile enterotoxin and those of cholera enterotoxin.

    PubMed

    Takeda, Y; Honda, T; Taga, S; Miwatani, T

    1981-11-01

    Heat-labile enterotoxin (LT) was purified from cells of enterotoxigenic Escherichia coli isolated from a patient with traveller's diarrhea. Purified LT was separated into A and B subunits by treatment with 6 M urea solution in 0.1 M propionic acid (pH 4.0). Biologically active toxin was reconstituted from isolated A and B subunits of LT. Hybrid toxins with biological activity were obtained in vitro from the A subunit of cholera enterotoxin and B subunit of LT, and from the A subunit of LT and B subunit of cholera enterotoxin. The hybrid toxins show a similar toxicity to that of the parent toxins from which the A subunits were derived. The in vitro formations of the hybrid toxins were confirmed by polyacrylamide gel disk electrophoresis. PMID:7309227

  2. Allele Variants of Enterotoxigenic Escherichia coli Heat-Labile Toxin Are Globally Transmitted and Associated with Colonization Factors

    PubMed Central

    Joffré, Enrique; von Mentzer, Astrid; Abd El Ghany, Moataz; Oezguen, Numan; Savidge, Tor; Dougan, Gordon; Svennerholm, Ann-Mari

    2014-01-01

    Enterotoxigenic Escherichia coli (ETEC) is a significant cause of morbidity and mortality in the developing world. ETEC-mediated diarrhea is orchestrated by heat-labile toxin (LT) and heat-stable toxins (STp and STh), acting in concert with a repertoire of more than 25 colonization factors (CFs). LT, the major virulence factor, induces fluid secretion after delivery of a monomeric ADP-ribosylase (LTA) and its pentameric carrier B subunit (LTB). A study of ETEC isolates from humans in Brazil reported the existence of natural LT variants. In the present study, analysis of predicted amino acid sequences showed that the LT amino acid polymorphisms are associated with a geographically and temporally diverse set of 192 clinical ETEC strains and identified 12 novel LT variants. Twenty distinct LT amino acid variants were observed in the globally distributed strains, and phylogenetic analysis showed these to be associated with different CF profiles. Notably, the most prevalent LT1 allele variants were correlated with major ETEC lineages expressing CS1 + CS3 or CS2 + CS3, and the most prevalent LT2 allele variants were correlated with major ETEC lineages expressing CS5 + CS6 or CFA/I. LTB allele variants generally exhibited more-stringent amino acid sequence conservation (2 substitutions identified) than LTA allele variants (22 substitutions identified). The functional impact of LT1 and LT2 polymorphisms on virulence was investigated by measuring total-toxin production, secretion, and stability using GM1–enzyme-linked immunosorbent assays (GM1-ELISA) and in silico protein modeling. Our data show that LT2 strains produce 5-fold more toxin than LT1 strains (P < 0.001), which may suggest greater virulence potential for this genetic variant. Our data suggest that functionally distinct LT-CF variants with increased fitness have persisted during the evolution of ETEC and have spread globally. PMID:25404692

  3. Multiplex PCR for detection of the heat-labile toxin gene and shiga-like toxin I and II genes in Escherichia coli isolated from natural waters.

    PubMed Central

    Lang, A L; Tsai, Y L; Mayer, C L; Patton, K C; Palmer, C J

    1994-01-01

    A triplex PCR method was developed to simultaneously amplify a heat-labile toxin sequence (LT) of 258 bp, a shiga-like toxin I sequence (SLT I) of 130 bp, and a shiga-like toxin II sequence (SLT II) of 346 bp from toxigenic strains of Escherichia coli. This method was used to screen 377 environmental E. coli isolates from marine waters or estuaries located in Southern California and North Carolina for enterotoxigenic or enterohemorrhagic E. coli strains. Of the 377 E. coli screened, one isolate was found to belong to the enterotoxigenic group, since it contained a LT homologous sequence, and one isolate was found to belong to the enterohemorrhagic group, since it contained a SLT I homologous sequence. None was found to contain SLT II homologous sequences. The pathogenicity of the positive environmental E. coli isolates was confirmed by standard bioassays with Y-1 adrenal cells and Vero cells to confirm toxin production. Our results suggest that toxigenic E. coli occurs infrequently in environmental waters and that there is a low public health risk from toxigenic E. coli in coastal waters. Images PMID:7944359

  4. Different Assay Conditions for Detecting the Production and Release of Heat-Labile and Heat-Stable Toxins in Enterotoxigenic Escherichia coli Isolates

    PubMed Central

    Rocha, Letícia B.; Ozaki, Christiane Y.; Horton, Denise S. P. Q.; Menezes, Caroline A.; Silva, Anderson; Fernandes, Irene; Magnoli, Fabio C.; Vaz, Tania M. I.; Guth, Beatriz E. C.; Piazza, Roxane M. F.

    2013-01-01

    Enterotoxigenic Escherichia coli (ETEC) produce heat-labile (LT) and/or heat-stable enterotoxins (ST). Despite that, the mechanism of action of both toxins are well known, there is great controversy in the literature concerning the in vitro production and release of LT and, for ST, no major concerns have been discussed. Furthermore, the majority of published papers describe the use of only one or a few ETEC isolates to define the production and release of these toxins, which hinders the detection of ETEC by phenotypic approaches. Thus, the present study was undertaken to obtain a better understanding of ST and LT toxin production and release under laboratory conditions. Accordingly, a collection of 90 LT-, ST-, and ST/LT-producing ETEC isolates was used to determine a protocol for toxin production and release aimed at ETEC detection. For this, we used previously raised anti-LT antibodies and the anti-ST monoclonal and polyclonal antibodies described herein. The presence of bile salts and the use of certain antibiotics improved ETEC toxin production/release. Triton X-100, as chemical treatment, proved to be an alternative method for toxin release. Consequently, a common protocol that can increase the production and release of LT and ST toxins could facilitate and enhance the sensitivity of diagnostic tests for ETEC using the raised and described antibodies in the present work. PMID:24316604

  5. Immunogenicity of Actinobacillus ApxIA toxin epitopes fused to the E. coli heat-labile enterotoxin B subunit.

    PubMed

    Bagdasarian, M M; Nagai, M; Frey, J; Bagdasarian, M

    1999-02-01

    Peptides KDYGASTGSSL (Epil). SLLRRRRNGEDVSV (Epi3) and DDEIYGNDGHP (Epi6), predicted to constitute immunogenic epitopes of the hemolysin-cytotoxin ApxIA of Actinobacillus pleuropneumoniae were inserted into a surface-exposed loop of the B subunit of the E. coli heat-labile enterotoxin (EtxB). The resulting chimeric proteins were recognized by monospecific antibodies against purified native ApxI and by convalescent sera of pigs that were positive for A. pleuropneumoniae serotype 1. Mice anti-sera against chimeric proteins EtxB::ApxIAEpi3 and EtxB::ApxIAEpi6 reacted with purified ApxI. These results indicate that Epi3 and Epi6 regions constitute linear epitopes of the structural ApxIA protein toxin. Epitope Epi6 which is located in the structure of the glycine rich repeats in ApxI elicits the formation of hemolysin neutralizing antibodies when introduced into mice in the form of a chimeric EtxB fusion protein. We suggest that fusion of peptide sequences to EtxB is a useful tool for the analysis of epitopes of complex proteins such as RTX toxins. PMID:10073721

  6. Single Chain Variable Fragments Produced in Escherichia coli against Heat-Labile and Heat-Stable Toxins from Enterotoxigenic E. coli

    PubMed Central

    Andrade, Fernanda B.; Nepomuceno, Roberto; Silva, Anderson; Munhoz, Danielle D.; Yamamoto, Bruno B.; Luz, Daniela; Abreu, Patrícia A. E.; Horton, Denise S. P. Q.; Elias, Waldir P.; Ramos, Oscar H. P.; Piazza, Roxane M. F.

    2015-01-01

    Background Diarrhea is a prevalent pathological condition frequently associated to the colonization of the small intestine by enterotoxigenic Escherichia coli (ETEC) strains, known to be endemic in developing countries. These strains can produce two enterotoxins associated with the manifestation of clinical symptoms that can be used to detect these pathogens. Although several detection tests have been developed, minimally equipped laboratories are still in need of simple and cost-effective methods. With the aim to contribute to the development of such diagnostic approaches, we describe here two mouse hybridoma-derived single chain fragment variable (scFv) that were produced in E. coli against enterotoxins of ETEC strains. Methods and Findings Recombinant scFv were developed against ETEC heat-labile toxin (LT) and heat-stable toxin (ST), from previously isolated hybridoma clones. This work reports their design, construction, molecular and functional characterization against LT and ST toxins. Both antibody fragments were able to recognize the cell-interacting toxins by immunofluorescence, the purified toxins by ELISA and also LT-, ST- and LT/ST-producing ETEC strains. Conclusion The developed recombinant scFvs against LT and ST constitute promising starting point for simple and cost-effective ETEC diagnosis. PMID:26154103

  7. Improved method for the routine identification of toxigenic Escherichia coli by DNA amplification of a conserved region of the heat-labile toxin A subunit.

    PubMed Central

    Victor, T; du Toit, R; van Zyl, J; Bester, A J; van Helden, P D

    1991-01-01

    This report describes a DNA amplification procedure for routine identification of heat-labile-toxin-producing Escherichia coli. Two oligonucleotide primers were used in a polymerase chain reaction procedure to amplify a highly conserved region of the A subunit of the heat-labile enterotoxin gene. Amplifications were done directly on E. coli colonies from plates when Salmonella, Shigella, or parasite infections were excluded as agents of the severe diarrhea in the patients. The conditions for the polymerase chain reaction method were empirically determined, and the procedure is inexpensive, sensitive, and specific. Positive results can be obtained over a wide variation in bacterial numbers, with no inhibition of Thermus aquaticus DNA polymerase. Detection of the amplified product can be done by agarose gel electrophoresis, which is specific and sensitive enough for routine diagnosis of this pathogen in clinical isolates. If greater sensitivity and specificity are required, hybridization with 32P- or alkaline phosphatase-labeled oligonucleotide probes can be used. Our results suggest that heat-labile-toxin-producing E. coli is responsible for about 9% of nondiagnosed diarrhea cases in Tygerberg Hospital, Tygerberg, Republic of South Africa. Images PMID:1993750

  8. Intranasal immunization with live recombinant Lactococcus lactis combined with heat-labile toxin B subunit protects chickens from highly pathogenic avian influenza H5N1 virus.

    PubMed

    Lei, Han; Peng, Xiaojue; Shu, Handing; Zhao, Daxian

    2015-01-01

    Development of safe and effective vaccines to prevent highly pathogenic avian influenza H5N1 virus infection is a challenging goal. Lactococcus lactis (L. lactis) is an ideal delivery vector for vaccine development, and it has been shown previously that oral immunization of encapsulated secretory L. lactis-hemagglutinin (HA) could provide complete protection against homologous H5N1 virus challenge in the mice model. While intranasal immunization is an appealing approach, it is now reported that secretory L. lactis-HA combined with mucosal adjuvant heat-labile toxin B subunit (LTB) could provide protective immunity in the chicken model. As compared to intranasal immunization with L. lactis-HA alone, L. lactis-HA combined with LTB (L. lactis-HA?+?LTB) could elicit robust neutralizing antibody responses and mucosal IgA responses, as well as strong cellular immune responses in the vaccinated chickens. Importantly, intranasal immunization with L. lactis-HA?+?LTB could provide 100% protection against H5N1 virus challenge. Taken together, these results suggest that intranasal immunization with L. lactis-HA?+?LTB can be considered as an effective approach for preventing and controlling infection of H5N1 virus in poultry during an avian influenza A/H5N1 pandemic. PMID:24861477

  9. Biophysical characteristics of cholera toxin and Escherichia coli heat-labile enterotoxin structure and chemistry lead to differential toxicity.

    PubMed

    Craft, John W; Shen, Tsai-Wei; Brier, Lindsey M; Briggs, James M

    2015-01-22

    The biophysical chemistry of macromolecular complexes confer their functional characteristics. We investigate the mechanisms that make the AB5 holotoxin of Vibrio cholerae (CT) a significantly more pathogenic molecule than the enterotoxin of Escherichia coli (LT) with which it shares 88% similarity and whose structure is homologous with a backbone RMSD of 0.84 Å and imposes its deleterious effects though the same process to constitutively ADP-ribosylate adenylate cyclase. We present computational data that characterizes the impact of amino acid variations in the A2 tail, which helps to explain experimental data that demonstrate CT's higher toxicity. A hydrophobic patch on the B pentamer interface and its interactions with the A subdomain are partially disrupted by the substitution of an aspartic acid (LT) for glycine in CT. CT's holotoxin has less solvent accessible surface area (94 Å(2) vs 54 Å(2)) and higher contact area (280 Å(2) vs 241 Å(2)) with S228, which is a gatekeeper, partially controlling the diffusion of water into the pore. CT excludes water from the top of the central pore whereas LT allows much more water to interact. These biophysical properties of the toxins lead to their differential toxicity and resulting impact to human health. PMID:25322200

  10. Heat-Labile Enterotoxin: Beyond GM1 Binding

    PubMed Central

    Mudrak, Benjamin; Kuehn, Meta J.

    2010-01-01

    Enterotoxigenic Escherichia coli (ETEC) is a significant source of morbidity and mortality worldwide. One major virulence factor released by ETEC is the heat-labile enterotoxin LT, which is structurally and functionally similar to cholera toxin. LT consists of five B subunits carrying a single catalytically active A subunit. LTB binds the monosialoganglioside GM1, the toxin’s host receptor, but interactions with A-type blood sugars and E. coli lipopolysaccharide have also been identified within the past decade. Here, we review the regulation, assembly, and binding properties of the LT B-subunit pentamer and discuss the possible roles of its numerous molecular interactions. PMID:22069646

  11. A functional antigen in a practical crop: LT-B producing maize protects mice against Escherichia coli heat labile enterotoxin (LT) and cholera toxin (CT)

    Microsoft Academic Search

    Rachel Chikwamba; Joan Cunnick; Diane Hathaway; Jennifer McMurray; Hugh Mason

    2002-01-01

    We have produced a functional heat labile enterotoxin (LT-) B subunit of Escherichia coli in maize. LT-B is a multimeric protein that presents an ideal model for an edible vaccine, displaying stability in the gut and inducing mucosal and systemic immune responses. Transgenic maize was engineered to synthesize the LT-B polypeptides, which assembled into oligomeric structures with affinity for GM1

  12. A Functional Antigen in a Practical Crop: LT-B Producing Maize Protects Mice against Escherichia coli Heat Labile Enterotoxin (LT) and Cholera Toxin (CT)

    Microsoft Academic Search

    Rachel Chikwamba; Joan Cunnick; Diane Hathaway; Jennifer McMurray; Hugh Mason; Kan Wang

    2002-01-01

    We have produced a functional heat labile enterotoxin (LT-) B subunit of Escherichia coli in maize. LT-B is a multimeric protein that presents an ideal model for an edible vaccine, displaying stability in the gut and inducing mucosal and systemic immune responses. Transgenic maize was engineered to synthesize the LT-B polypeptides, which assembled into oligomeric structures with affinity for GM1

  13. Structure and mucosal adjuvanticity of cholera and Escherichia coli heat-labile enterotoxins

    Microsoft Academic Search

    Rino Rappuoli; Mariagrazia Pizza; Gill Douce; Gordon Dougan

    1999-01-01

    Escherichia coli heat-labile enterotoxin and cholera toxin are potent mucosal immunogens and adjuvants in animal models. Non-toxic mutants retaining adjuvant activity are useful tools to dissect the mechanism of mucosal adjuvanticity and promising candidates for development of human vaccines and immunotherapy. Clinical trials are expected to proceed in the near future.

  14. Analysis and modeling of heat-labile enterotoxins of Escherichia coli suggests a novel space with insights into receptor preference.

    PubMed

    Krishna Raja, M; Ghosh, Asit Ranjan; Vino, S; Sajitha Lulu, S

    2015-08-01

    Features of heat-labile enterotoxins of Escherichia coli which make them fit to use as novel receptors for antidiarrheals are not completely explored. Data-set of 14 different serovars of enterotoxigenic Escherichia coli producing heat-labile toxins were taken from NCBI Genbank database and used in the study. Sequence analysis showed mutations in different subunits and also at their interface residues. As these toxins lack crystallography structures, homology modeling using Modeller 9.11 led to the structural approximation for the E. coli producing heat-labile toxins. Interaction of modeled toxin subunits with proanthocyanidin, an antidiarrheal showed several strong hydrogen bonding interactions at the cost of minimized energy. The hits were subsequently characterized by molecular dynamics simulation studies to monitor their binding stabilities. This study looks into novel space where the ligand can choose the receptor preference not as a whole but as an individual subunit. Mutation at interface residues and interaction among subunits along with the binding of ligand to individual subunits would help to design a non-toxic labile toxin and also to improve the therapeutics. PMID:25375068

  15. Assay of heat-labile enterotoxins by their ADP-ribosyltransferase activities.

    PubMed Central

    Narayanan, J; Hartman, P A; Graves, D J

    1989-01-01

    Simple enzymatic assays to detect heat-labile enterotoxins whose modes of action are similar to that of cholera toxin were evaluated. The assays are performed by using an artificial substrate, diethylamino benzylidine-aminoguanidine, which is an ADP-ribose acceptor. The product, formed in the presence of NAD+, can be quantitated by spectrofluorometric, spectrophotometric, or high-performance liquid chromatographic (HPLC) methods. As little as 25 ng (spectrofluorometry) or 125 ng (spectrophotometry or HPLC) of cholera toxin can be detected in an assay volume of 250 microliters. The detection limit for heat-labile enterotoxin by either the spectrophotometric or HPLC methods was 125 ng/250 microliters. Because the results are quantitative, the enzymatic methods can be used for medium development, determination of factors that influence toxin production, and other applications that heretofore could be accomplished only with difficulty. The enzymatic methods add a new dimension to the assay of toxins that ribosylate arginine residues of proteins. Sensitivities of the assays might be improved by developing better synthetic substrates, and applications could be broadened by the development of artificial substrates containing other functional groups. PMID:2509510

  16. Development and Accuracy of Quantitative Real-Time Polymerase Chain Reaction Assays for Detection and Quantification of Enterotoxigenic Escherichia coli (ETEC) Heat Labile and Heat Stable Toxin Genes in Travelers' Diarrhea Samples

    PubMed Central

    Youmans, Bonnie P.; Ajami, Nadim J.; Jiang, Zhi-Dong; Petrosino, Joseph F.; DuPont, Herbert L.; Highlander, Sarah K.

    2014-01-01

    Enterotoxigenic Escherichia coli (ETEC), the leading bacterial pathogen of travelers' diarrhea, is routinely detected by an established DNA hybridization protocol that is neither sensitive nor quantitative. Quantitative real-time polymerase chain reaction (qPCR) assays that detect the ETEC toxin genes eltA, sta1, and sta2 in clinical stool samples were developed and tested using donor stool inoculated with known quantities of ETEC bacteria. The sensitivity of the qPCR assays is 89%, compared with 22% for the DNA hybridization assay, and the limits of detection are 10,000-fold lower than the DNA hybridization assays performed in parallel. Ninety-three clinical stool samples, previously characterized by DNA hybridization, were tested using the new ETEC qPCR assays. Discordant toxin profiles were observed for 22 samples, notably, four samples originally typed as ETEC negative were ETEC positive. The qPCR assays are unique in their sensitivity and ability to quantify the three toxin genes in clinical stool samples. PMID:24189361

  17. Escherichia coli heat-labile toxin subunit B fusions with Streptococcus sobrinus antigens expressed by Salmonella typhimurium oral vaccine strains: importance of the linker for antigenicity and biological activities of the hybrid proteins.

    PubMed Central

    Jagusztyn-Krynicka, E K; Clark-Curtiss, J E; Curtiss, R

    1993-01-01

    A set of vectors possessing the genes for aspartate semialdehyde dehydrogenase (asd) and the B subunit of the heat-labile enterotoxin of Escherichia coli (LT-B) has been developed. These vectors allow operon or gene fusions of foreign gene epitopes at the C-terminal end of LT-B. Two groups of vectors have been constructed with and without leader sequences to facilitate placing of the foreign antigen in different cell compartments. Two Streptococcus sobrinus genes coding for principal colonization factors, surface protein antigen A (SpaA), and dextranase (Dex), have been fused into the 3' end of the LT-B gene. Resulting protein fusions of approximately 120 to 130 kDa are extremely well recognized by antibodies directed against both SpaA and Dex as well as against LT-B domains and retain the enzymatic activity of dextranase and the biological activity of LT-B in that they bind to GM1 gangliosides. Maximum antigenicity was obtained with the vector possessing an intervening linker of at least six amino acids with two proline residues. Some of the fusion proteins also exhibited another property of LT-B in that they were exported into the periplasm where they oligomerized. LT-B-SpaA and LT-B-Dex hybrid proteins are expressed stably and at a high level in avirulent Salmonella typhimurium vaccine strains which are being used to investigate their immunogenicity and types of induced immune responses. The fusion vectors will also be useful for production and purification of LT-B fusion antigens to be used and evaluated in other vaccine compositions. Images PMID:8432584

  18. Effect of site-directed mutagenic alterations on ADP-ribosyltransferase activity of the A subunit of Escherichia coli heat-labile enterotoxin.

    PubMed Central

    Lobet, Y; Cluff, C W; Cieplak, W

    1991-01-01

    Previous studies of the S1 subunit of pertussis toxin, an NAD(+)-dependent ADP-ribosyltransferase, suggested that a small amino-terminal region of amino acid sequence similarity to the active fragments of both cholera toxin and Escherichia coli heat-labile enterotoxin represents a region containing critical active-site residues that might be involved in the binding of the substrate NAD+. Other studies of two other bacterial toxins possessing ADP-ribosyltransferase activity, diphtheria toxin and Pseudomonas exotoxin A, have revealed the presence of essential glutamic acid residues vicinal to the active site. To help determine the relevance of these observations to activities of the enterotoxins, the A-subunit gene of the E. coli heat-labile enterotoxin was subjected to site-specific mutagenesis in the region encoding the amino-terminal region of similarity to the S1 subunit of pertussis toxin delineated by residues 6 through 17 and at two glutamic acid residues, 110 and 112, that are conserved in the active domains of all of the heat-labile enterotoxin variants and in cholera toxin. Mutant proteins in which arginine 7 was either deleted or replaced with lysine exhibited undetectable levels of ADP-ribosyltransferase activity. However, limited trypsinolysis of the arginine 7 mutants yielded fragmentation kinetics that were different from that yielded by the wild-type recombinant subunit or the authentic A subunit. In contrast, mutant proteins in which glutamic acid residues at either position 110 or 112 were replaced with aspartic acid responded like the wild-type subunit upon limited trypsinolysis, while exhibiting severely depressed, but detectable, ADP-ribosyltransferase activity. The latter results may indicate that either glutamic acid 110 or glutamic acid 112 of the A subunit of heat-labile enterotoxin is analogous to those active-site glutamic acids identified in several other ADP-ribosylating toxins. Images PMID:1908825

  19. Heat-labile Enterotoxins as Adjuvants or Anti-Inflammatory Agents

    PubMed Central

    Liang, Shuang; Hajishengallis, George

    2010-01-01

    Escherichia coli and Vibrio cholerae produce structurally related AB5-type heat-labile enterotoxins which are classified into two major types. The Type I subfamily includes cholera toxin and E. coli LT-I, whereas the Type II subfamily comprises LT-IIa and LT-IIb. In addition to their roles in microbial pathogenesis, the enterotoxins are widely and intensively studied for their exceptionally strong adjuvant and immunomodulatory activities, which are not necessarily dependent upon their abilities to elevate intracellular cAMP levels. Despite general structural similarities, these molecules, in intact or derivative form, display notable differences in their interactions with gangliosides or Toll-like receptors. This divergence results in differential immune response outcomes, the underlying mechanisms of which remain largely uncharacterized. Whereas the study of these molecules has been pivotal in understanding basic mechanisms of immune regulation, a formidable challenge is to dissociate toxicity from useful properties that can be exploited in vaccine development or for the treatment of autoimmune inflammatory diseases. PMID:20461887

  20. Simultaneous Exposure to Escherichia coli Heat-Labile and Heat-Stable Enterotoxins Increases Fluid Secretion and Alters Cyclic Nucleotide and Cytokine Production by Intestinal Epithelial Cells

    PubMed Central

    Read, Lisa T.; Hahn, Rachel W.; Thompson, Carli C.; Bauer, David L.; Norton, Elizabeth B.

    2014-01-01

    Enterotoxigenic Escherichia coli (ETEC) is a significant cause of diarrheal disease and death, especially in children in developing countries. ETEC causes disease by colonizing the small intestine and producing heat-labile toxin (LT), heat-stable toxin (ST), or both LT and ST (LT+ST). The majority of ETEC strains produce both ST and LT. Despite the prevalence of LT+ST-producing organisms, few studies have examined the physiologic or immunologic consequences of simultaneous exposure to these two potent enterotoxins. In the current report, we demonstrate that when LT and ST are both present, they increase water movement into the intestinal lumen over and above the levels observed with either toxin alone. As expected, cultured intestinal epithelial cells increased their expression of intracellular cyclic GMP (cGMP) when treated with ST and their expression of intracellular cyclic AMP (cAMP) when treated with LT. When both toxins were present, cGMP levels but not cAMP levels were synergistically elevated compared with the levels of expression caused by the corresponding single-toxin treatment. Our data also demonstrate that the levels of inflammatory cytokines produced by intestinal epithelial cells in response to LT are significantly reduced in animals exposed to both enterotoxins. These findings suggest that there may be complex differences between the epithelial cell intoxication and, potentially, secretory outcomes induced by ETEC strains expressing LT+ST compared with strains that express LT or ST only. Our results also reveal a novel mechanism wherein ST production may reduce the hosts' ability to mount an effective innate or adaptive immune response to infecting organisms. PMID:25287923

  1. Type II Heat-Labile Enterotoxins from 50 Diverse Escherichia coli Isolates Belong Almost Exclusively to the LT-IIc Family and May Be Prophage Encoded

    PubMed Central

    Jobling, Michael G.; Holmes, Randall K.

    2012-01-01

    Some enterotoxigenic Escherichia coli (ETEC) produce a type II heat-labile enterotoxin (LT-II) that activates adenylate cyclase in susceptible cells but is not neutralized by antisera against cholera toxin or type I heat-labile enterotoxin (LT-I). LT-I variants encoded by plasmids in ETEC from humans and pigs have amino acid sequences that are ?95% identical. In contrast, LT-II toxins are chromosomally encoded and are much more diverse. Early studies characterized LT-IIa and LT-IIb variants, but a novel LT-IIc was reported recently. Here we characterized the LT-II encoding loci from 48 additional ETEC isolates. Two encoded LT-IIa, none encoded LT-IIb, and 46 encoded highly related variants of LT-IIc. Phylogenetic analysis indicated that the predicted LT-IIc toxins encoded by these loci could be assigned to 6 subgroups. The loci corresponding to individual toxins within each subgroup had DNA sequences that were more than 99% identical. The LT-IIc subgroups appear to have arisen by multiple recombinational events between progenitor loci encoding LT-IIc1- and LT-IIc3-like variants. All loci from representative isolates encoding the LT-IIa, LT-IIb, and each subgroup of LT-IIc enterotoxins are preceded by highly-related genes that are between 80 and 93% identical to predicted phage lysozyme genes. DNA sequences immediately following the B genes differ considerably between toxin subgroups, but all are most closely related to genomic sequences found in predicted prophages. Together these data suggest that the LT-II loci are inserted into lambdoid type prophages that may or may not be infectious. These findings raise the possibility that production of LT-II enterotoxins by ETEC may be determined by phage conversion and may be activated by induction of prophage, in a manner similar to control of production of Shiga-like toxins by converting phages in isolates of enterohemmorhagic E. coli. PMID:22242186

  2. Force relaxation, labile heat and parvalbumin content of skeletal muscle fibres of Xenopus laevis.

    PubMed Central

    Lännergren, J; Elzinga, G; Stienen, G J

    1993-01-01

    1. Measurements were made of stable (hb) and labile (ha) maintenance heat rate, slowing of relaxation as a function of tetanus duration, and parvalbumin (PA) content in intact single muscle fibres of types 1 and 2 from Xenopus laevis. The majority of experiments were performed at 20 degrees C. In addition, total and myofibrillar ATPase activity was measured in skinned Xenopus fibres, also of types 1 and 2; these studies were performed at 4 degrees C. 2. In agreement with a previous study hb was significantly higher in type 1 (175 +/- 13 mW (g wet wt)-1; n = 8) than in type 2 fibres (88 +/- 9 mW (g wet wt)-1; n = 7). The value of ha was 236 +/- 22 and 117 +/- 16 mW (g wet wt)-1, respectively (mean +/- S.E.M.). ha decayed with a time constant of 0.27 +/- 0.02 (n = 8) and 0.33 +/- 0.02 s (n = 7). 3. The early relaxation rate of tetanic force, extrapolated to the onset of stimulation (yo + yb; where yo is 'extra' rate of relaxation and yb steady rate) was 85.6 +/- 4.2 s-1 for type 1 fibres (n = 8) and 62.7 +/- 7.3 s-1 for type 2 fibres (n = 7). Relaxation rate at the end of a 1.8 s tetanus (yb) was 29.4 +/- 1.6 and 33.3 +/- 1.5 s-1, respectively; thus, there was more slowing with tetanus duration in type 1 fibres. The time constant for slowing of relaxation with tetanus duration was similar to that for decay of ha. 4. Parvalbumin concentration, [PA], was 0.45 +/- 0.04 mM in type 1 (n = 7) and 0.22 +/- 0.04 mM (n = 7) in type 2 fibres. 5. For individual fibres positive correlations were found between the 'extra' rate of relaxation (yo), labile heat (ha) and [PA]. Significantly more labile heat was liberated than can be accounted for by the enthalpy change of Ca2+ binding to PA. 6. For five fibres (type 1) studied both at 20 and 10 degrees C, the magnitude of slowing of relaxation, expressed as yo/(yo + yb), was 0.58 +/- 0.03 at 20 degrees C and 0.65 +/- 0.03 at 10 degrees C. 7. Both slowing of relaxation and labile heat were depressed in the second of two closely spaced tetani in type 1 fibres. Repriming of both effects followed similar, biphasic time courses and required more than 10 min for completion at 20 degrees C.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:8246178

  3. Transcutaneous immunization with heat-labile enterotoxin: development of a needle-free vaccine patch.

    PubMed

    Glenn, Gregory M; Flyer, David C; Ellingsworth, Larry R; Frech, Sarah A; Frerichs, David M; Seid, Robert C; Yu, Jianmei

    2007-10-01

    The skin is an attractive target for vaccine delivery. Adjuvants and antigens delivered into the skin can result in potent immune responses and an unmatched safety profile. The heat-labile enterotoxin (LT) from Escherichia coli, which acts both as antigen and adjuvant, has been shown to be delivered to human skin efficiently when used in a patch, resulting in strong immune responses. Iomai scientists have capitalized on these observations to develop late-stage products based on LT. This has encouraged commercial-level product development of a delivery system that is efficient, user-friendly and designed to address important medical needs. Over the past 2 years, extensive clinical testing and optimization has allowed the patch to evolve to a late-stage product. As a strategy for approval of a revolutionary vaccine-delivery system, the singular focus on optimization of LT delivery has enabled technical progress to extend patch-vaccine product development beyond LT. The field efficacy of the LT-based travelers' diarrhea vaccine has validated this approach. The discussion of transcutaneous immunization is unique, in that any consideration of the adjuvant must also include delivery, and the significant advances in a commercial patch application system are described. In this review, we integrate these concepts, update the clinical data and look to the future. PMID:17931160

  4. Role of receptor binding in toxicity, immunogenicity, and adjuvanticity of Escherichia coli heat-labile enterotoxin.

    PubMed Central

    Guidry, J J; Cárdenas, L; Cheng, E; Clements, J D

    1997-01-01

    The role of receptor binding in the toxicity, immunogenicity, and adjuvanticity of the heat-labile enterotoxin of Escherichia coli (LT) was examined by comparing native LT and LT(G33D), a B-subunit receptor binding mutant, with respect to the ability to bind to galactose and to GM1, toxicity on mouse Y-1 adrenal tumor cells, the ability to stimulate adenylate cyclase in Caco-2 cells, enterotoxicity in the patent mouse model, and oral immunogenicity and adjuvanticity. In contrast to native LT, LT(G33D) was unable to bind to the galactosyl moiety of Sepharose 4B or GM1 but did retain the lectin-like ability to bind to immobilized galactose on 6% agarose beads. LT(G33D) had no enterotoxicity in the patent mouse model but exhibited residual toxicity on mouse Y-1 adrenal tumor cells and had an ability equivalent to that of native LT to stimulate adenylate cyclase in Caco-2 cells (5,000 versus 6,900 pmol per mg of protein). In addition, LT(G33D) was unable to serve as an effective oral adjuvant for induction of immunoglobulin G or A directed against a coadministered antigen. Furthermore, LT(G33D) elicited negligible serum and mucosal antibody responses against itself. These data indicate that the toxicity, immunogenicity, and oral adjuvanticity of LT are dependent upon binding of the B subunit to ganglioside GM1. PMID:9393780

  5. Activation of Escherichia coli heat-labile enterotoxins by native and recombinant adenosine diphosphate-ribosylation factors, 20-kD guanine nucleotide-binding proteins.

    PubMed Central

    Lee, C M; Chang, P P; Tsai, S C; Adamik, R; Price, S R; Kunz, B C; Moss, J; Twiddy, E M; Holmes, R K

    1991-01-01

    Escherichia coli heat-labile enterotoxins (LT) are responsible in part for "traveler's diarrhea" and related diarrheal illnesses. The family of LTs comprises two serogroups termed LT-I and LT-II; each serogroup includes two or more antigenic variants. The effects of LTs result from ADP ribosylation of Gs alpha, a stimulatory component of adenylyl cyclase; the mechanism of action is identical to that of cholera toxin (CT). The ADP-ribosyltransferase activity of CT is enhanced by 20-kD guanine nucleotide-binding proteins, known as ADP-ribosylation factors or ARFs. These proteins directly activate the CTA1 catalytic unit and stimulate its ADP ribosylation of Gs alpha, other proteins, and simple guanidino compounds (e.g., agmatine). Because of the similarities between CT and LTs, we investigated the effects of purified bovine brain ARF and a recombinant form of bovine ARF synthesized in Escherichia coli on LT activity. ARF enhanced the LT-I-, LT-IIa-, and LT-IIb-catalyzed ADP ribosylation of agmatine, as well as the auto-ADP ribosylation of the toxin catalytic unit. Stimulation of ADP-ribosylagmatine formation by LTs and CT in the presence of ARF was GTP dependent and enhanced by sodium dodecyl sulfate. With agmatine as substrate, LT-IIa and LT-IIb exhibited less than 1% the activity of CT and LT-Ih. CT and LTs catalyzed ADP-ribosyl-Gs alpha formation in a reaction dependent on ARF, GTP, and dimyristoyl phosphatidylcholine/cholate. With Gs alpha as substrate, the ADP-ribosyltransferase activities of the toxins were similar, although CT and LT-Ih appeared to be slightly more active than LT-IIa and LT-IIb. Thus, LT-IIa and LT-IIb appear to differ somewhat from CT and LT-Ih in substrate specificity. Responsiveness to stimulation by ARF, GTP, and phospholipid/detergent as well as the specificity of ADP-ribosyltransferase activity are functions of LTs from serogroups LT-I and LT-II that are shared with CT. Images PMID:1902492

  6. Purification and properties of a cytolytic toxin in venom of the jellyfish Carybdea marsupialis

    Microsoft Academic Search

    Giandomenico Rottini; Laura Gusmani; Elisabetta Parovel; Massimo Avian; Pierluigi Patriarca

    1995-01-01

    A haemolytic toxin was purified by ion-exchange chromatography and FPLC gel filtration from the nematocysts of the jellyfish Carybdea marsupialis. Sheep red cells, but not human or rabbit red cells, were susceptible to lysis by the toxin. The toxin is a protein with an apparent molecular mass of about 102–107 kDa, is heat labile, highly unstable in polar media, inactivated

  7. Characterization of two different toxins of Wickerhamomyces anomalus (Pichia anomala) VKM Y-159.

    PubMed

    Farkas, Z; Márki-Zay, J; Kucsera, Judit; Vágvölgyi, Cs; Golubev, W I; Pfeiffer, Ilona

    2012-06-01

    Wickerhamomyces anomalus VKM Y-159 strain produces two types of toxin designated as WAKT a and WAKT b, encoded by chromosomal genes. The WAKT a toxin is heat-labile, pronase sensitive acting in pH range 3-4 affecting on several yeasts including pathogenic Candida species while the WAKT b toxin is protease- and thermo-resistant, acting in pH range 3-7 on two species, Candida alai and Candida norvegica. The rapid decrease of the number of viable cells after toxin treatment demonstrates that both toxins have cytocidic effect. PMID:22695525

  8. Preparation of biocompatible heat-labile enterotoxin subunit B-bovine serum albumin nanoparticles for improving tumor-targeted drug delivery via heat-labile enterotoxin subunit B mediation

    PubMed Central

    Zhao, Liang; Su, Rongjian; Cui, Wenyu; Shi, Yijie; Liu, Liwei; Su, Chang

    2014-01-01

    Heat-labile enterotoxin subunit B (LTB) is a non-catalytic protein from a pentameric subunit of Escherichia coli. Based on its function of binding specifically to ganglioside GM1 on the surface of cells, a novel nanoparticle (NP) composed of a mixture of bovine serum albumin (BSA) and LTB was designed for targeted delivery of 5-fluorouracil to tumor cells. BSA-LTB NPs were characterized by determination of their particle size, polydispersity, morphology, drug encapsulation efficiency, and drug release behavior in vitro. The internalization of fluorescein isothiocyanate-labeled BSA-LTB NPs into cells was observed using fluorescent imaging. Results showed that BSA-LTB NPs presented a narrow size distribution with an average hydrodynamic diameter of approximately 254±19 nm and a mean zeta potential of approximately ?19.95±0.94 mV. In addition, approximately 80.1% of drug was encapsulated in NPs and released in the biphasic pattern. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay showed that BSA-LTB NPs exhibited higher cytotoxic activity than non-targeted NPs (BSA NPs) in SMMC-7721 cells. Fluorescent imaging results proved that, compared with BSA NPs, BSA-LTB NPs could greatly enhance cellular uptake. Hence, the results indicate that BSA-LTB NPs could be a potential nanocarrier to improve targeted delivery of 5-fluorouracil to tumor cells via mediation of LTB. PMID:24851048

  9. Isolation and characterization of homogeneous heat-labile enterotoxins with high specific activity from Escherichia coli cultures.

    PubMed Central

    Clements, J D; Finkelstein, R A

    1979-01-01

    The heat-labile enterotoxin (LT) has been isolated in homogeneous form with high specific activity from three sources: cell-free supernatant, NaCl extract, and whole-cell lysates of an enterotoxigenic Escherichia coli strain. In vitro immunological assays were used in lieu of tedious and highly variable bioassays to recognize fractions with activity. This revealed that the major portion of the LT remained adherent to columns containing agarose, from which it could be eluted quantitatively in practically homogeneous form by galactose. Isolated LT has remarkable similarities to the cholera enterotoxin (choleragen) in both subunit structure and amino acid composition, although there are also notable differences in these two enterotoxins, which are related immunologically and by mode of action. Unlike choleragen, in which the A region is totally nicked, E. coli LT, depending on its source, is activated by proteolytic processing. The activity of LT is equivalent to that of choleragen in bioassays on adrenal cells, in rabbit skin, and in rabbit ileal loops, especially when, depending on the source of material, the LT has been activated by treatment with trypsin. The whole-cell lysate is the richest source of LT. Images PMID:89088

  10. Peracetic acid: a practical agent for sterilizing heat-labile polymeric tissue-engineering scaffolds.

    PubMed

    Yoganarasimha, Suyog; Trahan, William R; Best, Al M; Bowlin, Gary L; Kitten, Todd O; Moon, Peter C; Madurantakam, Parthasarathy A

    2014-09-01

    Advanced biomaterials and sophisticated processing technologies aim at fabricating tissue-engineering scaffolds that can predictably interact within a biological environment at the cellular level. Sterilization of such scaffolds is at the core of patient safety and is an important regulatory issue that needs to be addressed before clinical translation. In addition, it is crucial that meticulously engineered micro- and nano- structures are preserved after sterilization. Conventional sterilization methods involving heat, steam, and radiation are not compatible with engineered polymeric systems because of scaffold degradation and loss of architecture. Using electrospun scaffolds made from polycaprolactone, a low melting polymer, and employing spores of Bacillus atrophaeus as biological indicators, we compared ethylene oxide, autoclaving and 80% ethanol to a known chemical sterilant, peracetic acid (PAA), for their ability to sterilize as well as their effects on scaffold properties. PAA diluted in 20% ethanol to 1000 ppm or above sterilized electrospun scaffolds in 15 min at room temperature while maintaining nano-architecture and mechanical properties. Scaffolds treated with PAA at 5000 ppm were rendered hydrophilic, with contact angles reduced to 0°. Therefore, PAA can provide economical, rapid, and effective sterilization of heat-sensitive polymeric electrospun scaffolds that are used in tissue engineering. PMID:24341350

  11. Inhibition of Cronobacter sakazakii by heat labile bacteriocins produced by probiotic LAB isolated from healthy infants.

    PubMed

    Awaisheh, Saddam S; Al-Nabulsi, Anas A; Osaili, Tareq M; Ibrahim, Salam; Holley, Richard

    2013-09-01

    Cronobacter sakazakii is an opportunistic pathogen that can cause bacteremia, meningitis, and necrotizing enterocolitis, most often in neonates with case-fatality rates that may reach 80%. The antimicrobial activity of lactic acid bacteria against a wide range of foodborne pathogens is well-established in different types of food products. The objective of the current study was to investigate the antibacterial activity of Lactobacillus acidophilus and L. casei isolated from feces of healthy infants against different strains of C. sakazakii in agar and a rehydrated infant milk formula (RIMF) model. The inhibition zones of C. sakazakii around L. acidophilus or L. casei ranged from 22 to 32 mm on eMan Rogosa Sharpe (MRS) agar under aerobic conditions, while a slight reduction in antibacterial activity was noted on modified MRS (0.2% glucose) under anaerobic conditions. It was observed that pH-neutralized cell-free supernatant (CFS) of L. acidophilus or L. casei was inhibitory against tested C. sakazakii strains. The inhibition zones of neutralized CFS were lower than the antibacterial activities of live cultures. The antibacterial activity of CFS was abolished when CFS from L. acidophilus or L. casei was heated at 60 or 80 °C for either 10 min or 2 h, or treated with trypsin or pepsin. This was considered strong evidence that the inhibition was due to the production of bacteriocins by L. casei and L. acidophilus. Both the CFS and active growing cells of L. casei and L. acidophilus were able to reduce the viability of C. sakazakii in the RIMF model. The results may extend the use of natural antimicrobials instead of conventional preservation methods to improve the safety of RIMF. PMID:23924352

  12. Studies on the Chick-lethal Toxin of Escherichia coli

    PubMed Central

    Truscott, R. B.

    1973-01-01

    A toxin which is lethal for two week old chicks has been recovered from strains of Escherichia coli O78:K80 of bovine and avian origin and from avian isolates of serogroups O2, O45 and O109. The toxin is heat-labile, antigenic, high in protein, inactivated by pronase, trypsin, amylase, and pancreatic lipase. The toxin may be precipitated by ammonium sulfate or TCA treatment from the supernatant obtained by repeated centrifugation of sonicated cells. Considerable purification has been obtained by column chromatography using Sepharose 6B. PMID:4270809

  13. Characterization of antigen-presenting cells induced by intragastric immunization with recombinant chimeric immunogens constructed from Streptococcus mutans AgI/II and type I or type II heat-labile enterotoxins.

    PubMed

    Zhao, W; Zhao, Z; Russell, M W

    2011-06-01

    Intragastric (i.g.) immunization with recombinant chimeric proteins constructed from the saliva-binding region (SBR) of Streptococcus mutans surface antigen AgI/II and the A2/B subunits of enterobacterial heat-labile enterotoxins has been successfully used to induce salivary and circulating antibodies against S. mutans that have protective potential against dental caries. To investigate the mode of action of these vaccine constructs, mice were immunized i.g. with chimeric proteins constructed from SBR and cholera toxin (CT) or the type II enterotoxins of Escherichia coli, LT-IIa and LT-IIb. Antigen-presenting cells (APC) in Peyer's patches (PP) and mesenteric lymph nodes (MLN) were characterized by flow cytometry. Compared with immunization with SBR alone, chimeric proteins SBR-LTIIaA2/B and SBR-LTIIbA2/B increased the number of B cells and macrophages in PP and diminished B cell numbers in MLN, whereas SBR-CTA2/B diminished the numbers of B cells and macrophages in PP and MLN. Immunization with all three chimeric proteins led to upregulation of MHC class II molecules and co-stimulatory receptors CD40, CD80, and CD86 especially on dendritic cells in PP and also on APC in MLN. The results provide a molecular basis for the enhanced immune responses induced by chimeric proteins compared with uncoupled antigen, and for differential responses to chimeric proteins based on CT or type II enterotoxins. PMID:21545697

  14. Treatment of PCR products with exonuclease I and heat-labile alkaline phosphatase improves the visibility of combined bisulfite restriction analysis

    SciTech Connect

    Watanabe, Kousuke; Emoto, Noriko; Sunohara, Mitsuhiro; Kawakami, Masanori; Kage, Hidenori; Nagase, Takahide; Ohishi, Nobuya [Department of Respiratory Medicine, The University of Tokyo Hospital, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8655 (Japan)] [Department of Respiratory Medicine, The University of Tokyo Hospital, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8655 (Japan); Takai, Daiya, E-mail: dtakai-ind@umin.ac.jp [Department of Clinical Laboratory, The University of Tokyo Hospital, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8655 (Japan)] [Department of Clinical Laboratory, The University of Tokyo Hospital, 7-3-1, Hongo, Bunkyo-ku, Tokyo 113-8655 (Japan)

    2010-08-27

    Research highlights: {yields} Incubating PCR products at a high temperature causes smears in gel electrophoresis. {yields} Smears interfere with the interpretation of methylation analysis using COBRA. {yields} Treatment with exonuclease I and heat-labile alkaline phosphatase eliminates smears. {yields} The elimination of smears improves the visibility of COBRA. -- Abstract: DNA methylation plays a vital role in the regulation of gene expression. Abnormal promoter hypermethylation is an important mechanism of inactivating tumor suppressor genes in human cancers. Combined bisulfite restriction analysis (COBRA) is a widely used method for identifying the DNA methylation of specific CpG sites. Here, we report that exonuclease I and heat-labile alkaline phosphatase can be used for PCR purification for COBRA, improving the visibility of gel electrophoresis after restriction digestion. This improvement is observed when restriction digestion is performed at a high temperature, such as 60 {sup o}C or 65 {sup o}C, with BstUI and TaqI, respectively. This simple method can be applied instead of DNA purification using spin columns or phenol/chloroform extraction. It can also be applied to other situations when PCR products are digested by thermophile-derived restriction enzymes, such as PCR restriction fragment length polymorphism (RFLP) analysis.

  15. Development of xMAP assay for detection of six protein toxins.

    PubMed

    Simonova, Maria A; Valyakina, Tatiana I; Petrova, Elena E; Komaleva, Ravilya L; Shoshina, Natalia S; Samokhvalova, Larisa V; Lakhtina, Olga E; Osipov, Igor V; Philipenko, Galina N; Singov, Evgeniy K; Grishin, Evgeniy V

    2012-08-01

    xMAP technology was used for simultaneous identification of six protein toxins (staphylococcal enterotoxins A and B, cholera toxin, ricin, botulinum toxin A, and heat labile toxin of E. coli). Monoclonal antibody-conjugated xMAP microspheres and biotinilated monoclonal antibodies were used to detect the toxins in a sandwich immunoassay format. The detection limits were found to be 0.01 ng/mL for staphylococcal enterotoxin A, cholera toxin, botulinum toxin A, and ricin in model buffer (PBS-BSA) and 0.1 ng/mL for staphylococcal enterotoxin B and LT. In a complex matrix, such as cow milk, the limits of detection for staphylococcal enterotoxins A and B, cholera toxin, botulinum toxin A, and ricin increased 2- to 5-fold, while for LT the detection limit increased 30-fold in comparison with the same analysis in PBS-BSA. In the both PBS-BSA and milk samples, the xMAP test system was 3-200 times (depending on the toxin) more sensitive than ELISA systems with the same pairs of monoclonal antibodies used. The time required for a simultaneous analysis of six toxins using the xMAP system did not exceed the time required for ELISA to analyze one toxin. In the future, the assay may be used in clinical diagnostics and for food and environmental monitoring. PMID:22794090

  16. Suppression of in vitro antibody response of human peripheral blood lymphocytes by a heat-labile factor in normal human serum.

    PubMed Central

    Aldo-Benson, M A; Petersen, B H; Benson, M D

    1981-01-01

    When fresh autologous serum was added to normal human peripheral blood lymphocytes (PBL), it suppressed greater than 90% of the in vitro anti-SRBC response of these cells. Heating the serum for 30 min at 56 degrees C reversed this suppression, Serum from a patient with rheumatoid arthritis and circulating immune complexes had no suppressive effect on the anti-SRBC response of normal human PBL, but serum from patients having the same disease, without circulating immune complexes, did suppress over 90% of the plaque-forming cell response. Serum from an agammaglobulinaemic patient was also suppressive. Addition of serum from patients with congenital deficiencies of C2, C3, C5 and C8 also has a suppressive effect. Absorption of normal serum with immune complexes markedly decreased levels of C1 and C4, and also reversed the suppressive effect of this serum. These data suggest that a heat-labile factor in normal human serum which can be absorbed by immune complexes suppresses the antibody response to a T-dependent antigen. Other immune suppressors found in normal human serum are heat-stable or do not suppress in the presence of normal serum proteins. Thus the suppressive protein described in these studies may be unique. It is possible that either C1 or C4 or both may play a role in the suppression noted here. PMID:7035034

  17. Cell clustering and delay/arrest in T-cell division implicate a novel mechanism of immune modulation by E. coli heat-labile enterotoxin B-subunits.

    PubMed

    El-Kassas, Seham; Faraj, Rawah; Martin, Karmarcha; Hajishengallis, George; Connell, Terry D; Nashar, Toufic

    2015-06-01

    The B-subunits of heat-labile enterotoxins LT-I (LT-IB) and LT-IIa (LT-IIaB) are strong adjuvants that bind to cell-surface receptors, including gangliosides GM1 and GD1b, respectively. LT-IIaB also binds TLR-2. We demonstrate for the first time that co-incubation with the B-subunits induces significant clustering of B cells after only 4h, and B and T cells in 24h. Clustering was dependent on intact B-subunits, but not on the TLR-2 binding activity of LT-IIaB, indicating it was ganglioside-mediated. Treatment of B cells with LT-IB, a mixture of LT-IB+LT-IIaB, but not LT-IIaB alone, caused a delay in T cell division following ovalbumin endocytosis. B cell receptor-mediated uptake in presence of each treatment caused an arrest, but with increased production of IL-2. Further, treatments differentially increased the proportion of macrophages expressing MHC class-II. These results highlight the outcomes of interplay between signals involving different receptors and implicate a novel mechanism of adjuvanticity. PMID:25880107

  18. The LTR72 Mutant of Heat-Labile Enterotoxin of Escherichia coli Enhances the Ability of Peptide Antigens To Elicit CD4+ T Cells and Secrete Gamma Interferon after Coapplication onto Bare Skin

    Microsoft Academic Search

    A.-S. Beignon; J.-P. Briand; R. Rappuoli; S. Muller; C. D. Partidos

    2002-01-01

    Application of antigens with an adjuvant onto bare skin is a needle-free and pain-free immunization procedure that delivers antigens to the immunocompetent cells of the epidermis. We tested here the immu- nogenicity and adjuvanticity of two mutants of heat-labile enterotoxin (LT) of Escherichia coli, LTK63 and LTR72. Both mutants were shown to be immunogenic, inducing serum and mucosal antibody responses.

  19. Analysis of heat-labile sites generated by reactions of depleted uranium and ascorbate in plasmid DNA.

    PubMed

    Wilson, Janice; Young, Ashley; Civitello, Edgar R; Stearns, Diane M

    2014-01-01

    The goal of this study was to characterize how depleted uranium (DU) causes DNA damage. Procedures were developed to assess the ability of organic and inorganic DNA adducts to convert to single-strand breaks (SSB) in pBR322 plasmid DNA in the presence of heat or piperidine. DNA adducts formed by methyl methanesulfonate, cisplatin, and chromic chloride were compared with those formed by reaction of uranyl acetate and ascorbate. Uranyl ion in the presence of ascorbate produced U-DNA adducts that converted to SSB on heating. Piperidine, which acted on DNA methylated by methyl methanesulfonate to convert methyl-DNA adducts to SSB, served in the opposite fashion as U-DNA adducts by decreasing the level of SSB. The observation that piperidine also decreased the gel shift for metal-DNA adducts formed by monofunctional cisplatin and chromic chloride was interpreted to suggest that piperidine served to remove U-DNA adducts. Radical scavengers did not affect the formation of uranium-induced SSB, suggesting that SSB arose from the presence of U-DNA adducts and not from the presence of free radicals. A model is proposed to predict how U-DNA adducts may serve as initial lesions that convert to SSB or AP sites. The results suggest that DU can act as a chemical genotoxin that does not require radiation for its mode of action. Characterizing the DNA lesions formed by DU is necessary to assess the relative importance of different DNA lesions in the formation of DU-induced mutations. Understanding the mechanisms of formation of DU-induced mutations may contribute to identification of biomarkers of DU exposure in humans. PMID:24218036

  20. Analysis of Heat-Labile Sites Generated by Reactions of Depleted Uranium and Ascorbate in Plasmid DNA

    PubMed Central

    Wilson, Janice; Young, Ashley; Civitello, Edgar R.

    2013-01-01

    The goal of this study was to characterize how depleted uranium (DU) causes DNA damage. Procedures were developed to assess the ability of organic and inorganic DNA adducts to convert to single strand breaks (SSB) in pBR322 plasmid DNA in the presence of heat or piperidine. DNA adducts formed by methyl methanesulfonate (MMS), cis-platin (cis-Pt), and chromic chloride were compared to those formed by reaction of uranyl acetate (UA) and ascorbate (Asc). Uranyl ion in the presence of Asc produced U-DNA adducts that converted to SSB upon heating. Piperidine, which acted on DNA methylated by MMS to convert methyl-DNA adducts to SSB, served in the opposite fashion with U-DNA adducts by decreasing SSB. The observation that piperidine also decreased the gel shift for metal-DNA adducts formed by monofunctional cis-Pt and chromic chloride was interpreted to suggest that piperidine served to remove U-DNA adducts. Radical scavengers did not affect formation of U-induced SSB, suggesting that SSB arose from the presence of U-DNA adducts and not from free radicals. A model is proposed to predict how U-DNA adducts may serve as initial lesions that convert to SSB or AP sites. Results suggest that DU can act as a chemical genotoxin that does not require radiation for its mode of action. Characterizing the DNA lesions formed by DU is necessary to assess the relative importance of different DNA lesions in the formation of DU-induced mutations. Understanding mechanisms of formation of DU-induced mutations may contribute to identification of biomarkers of DU exposures in humans. PMID:24218036

  1. Salmonella enterica serovar enteritidis ghosts carrying the Escherichia coli heat-labile enterotoxin B subunit are capable of inducing enhanced protective immune responses.

    PubMed

    Jawale, Chetan V; Lee, John Hwa

    2014-06-01

    The Escherichia coli heat-labile enterotoxin B subunit (LTB) is a potent vaccine adjuvant. Salmonella enterica serovar Enteritidis ghosts carrying LTB (S. Enteritidis-LTB ghosts) were genetically constructed using a novel plasmid, pJHL187-LTB, designed for the coexpression of the LTB and E lysis proteins. S. Enteritidis-LTB ghosts were characterized using scanning electron microscopy to visualize their transmembrane tunnel structures. The expression of LTB in S. Enteritidis-LTB ghost preparations was confirmed by immunoblot and enzyme-linked immunosorbent assays. The parenteral adjuvant activity of LTB was demonstrated by immunizing chickens with either S. Enteritidis-LTB ghosts or S. Enteritidis ghosts. Chickens were intramuscularly primed at 5 weeks of age and subsequently boosted at 8 weeks of age. In total, 60 chickens were equally divided into three groups (n = 20 for each): group A, nonvaccinated control; group B, immunized with S. Enteritidis-LTB ghosts; and group C, immunized with S. Enteritidis ghosts. Compared with the nonimmunized chickens (group A), the immunized chickens (groups B and C) exhibited increased titers of plasma IgG and intestinal secretory IgA antibodies. The CD3(+) CD4(+) subpopulation of T cells was also significantly increased in both immunized groups. Among the immunized chickens, those in group B exhibited significantly increased titers of specific plasma IgG and intestinal secretory IgA (sIgA) antibodies compared with those in group C, indicating the immunomodulatory effects of the LTB adjuvant. Furthermore, both immunized groups exhibited decreased bacterial loads in their feces and internal organs. These results indicate that parenteral immunization with S. Enteritidis-LTB ghosts can stimulate superior induction of systemic and mucosal immune responses compared to immunization with S. Enteritidis ghosts alone, thus conferring efficient protection against salmonellosis. PMID:24671556

  2. Salmonella enterica Serovar Enteritidis Ghosts Carrying the Escherichia coli Heat-Labile Enterotoxin B Subunit Are Capable of Inducing Enhanced Protective Immune Responses

    PubMed Central

    Jawale, Chetan V.

    2014-01-01

    The Escherichia coli heat-labile enterotoxin B subunit (LTB) is a potent vaccine adjuvant. Salmonella enterica serovar Enteritidis ghosts carrying LTB (S. Enteritidis-LTB ghosts) were genetically constructed using a novel plasmid, pJHL187-LTB, designed for the coexpression of the LTB and E lysis proteins. S. Enteritidis-LTB ghosts were characterized using scanning electron microscopy to visualize their transmembrane tunnel structures. The expression of LTB in S. Enteritidis-LTB ghost preparations was confirmed by immunoblot and enzyme-linked immunosorbent assays. The parenteral adjuvant activity of LTB was demonstrated by immunizing chickens with either S. Enteritidis-LTB ghosts or S. Enteritidis ghosts. Chickens were intramuscularly primed at 5 weeks of age and subsequently boosted at 8 weeks of age. In total, 60 chickens were equally divided into three groups (n = 20 for each): group A, nonvaccinated control; group B, immunized with S. Enteritidis-LTB ghosts; and group C, immunized with S. Enteritidis ghosts. Compared with the nonimmunized chickens (group A), the immunized chickens (groups B and C) exhibited increased titers of plasma IgG and intestinal secretory IgA antibodies. The CD3+ CD4+ subpopulation of T cells was also significantly increased in both immunized groups. Among the immunized chickens, those in group B exhibited significantly increased titers of specific plasma IgG and intestinal secretory IgA (sIgA) antibodies compared with those in group C, indicating the immunomodulatory effects of the LTB adjuvant. Furthermore, both immunized groups exhibited decreased bacterial loads in their feces and internal organs. These results indicate that parenteral immunization with S. Enteritidis-LTB ghosts can stimulate superior induction of systemic and mucosal immune responses compared to immunization with S. Enteritidis ghosts alone, thus conferring efficient protection against salmonellosis. PMID:24671556

  3. Toxin-mediated effects on the innate mucosal defenses: implications for enteric vaccines.

    PubMed

    Glenn, Gregory M; Francis, David H; Danielsen, E Michael

    2009-12-01

    Recent studies have confirmed older observations that the enterotoxins enhance enteric bacterial colonization and pathogenicity. How and why this happens remains unknown at this time. It appears that toxins such as the heat-labile enterotoxin (LT) from Escherichia coli can help overcome the innate mucosal barrier as a key step in enteric pathogen survival. We review key observations relevant to the roles of LT and cholera toxin in protective immunity and the effects of these toxins on innate mucosal defenses. We suggest either that toxin-mediated fluid secretion mechanically disrupts the mucus layer or that toxins interfere with innate mucosal defenses by other means. Such a breach gives pathogens access to the enterocyte, leading to binding and pathogenicity by enterotoxigenic E. coli (ETEC) and other organisms. Given the common exposure to LT(+) ETEC by humans visiting or residing in regions of endemicity, barrier disruption should frequently render the gut vulnerable to ETEC and other enteric infections. Conversely, toxin immunity would be expected to block this process by protecting the innate mucosal barrier. Years ago, Peltola et al. (Lancet 338:1285-1289, 1991) observed unexpectedly broad protective effects against LT(+) ETEC and mixed infections when using a toxin-based enteric vaccine. If toxins truly exert barrier-disruptive effects as a key step in pathogenesis, then a return to classic toxin-based vaccine strategies for enteric disease is warranted and can be expected to have unexpectedly broad protective effects. PMID:19737904

  4. Heat-induced transcription of diphtheria toxin A or its variants, CRM176 and CRM197: implications for pancreatic cancer gene therapy

    Microsoft Academic Search

    P Fogar; F Navaglia; D Basso; C-F Zambon; L Moserle; S Indraccolo; A Stranges; E Greco; E Fadi; A Padoan; G Pantano; M C Sanzari; S Pedrazzoli; C Montecucco; M Plebani

    2010-01-01

    Vectors combining the heat shock proteins (HSPs) promoter with the catalytic subunit A of the diphtheria toxin (DTA) or its variants, cross-reacting material (CRM) 176 and 197, were engineered to investigate the effect of bacterial toxins on pancreatic cancer (PC) cells. Three heat-inducible enhanced green fluorescent protein (eGFP)-expression vectors were obtained: V1 (91% homology to HSPA6), V2 (five heat shock

  5. Analysis and application of a neutralizing linear epitope on liable toxin B of enterotoxin Escherichia coli.

    PubMed

    Guan, Weikun; Liu, Wenxin; Bao, Jun; Li, Jinping; Yuan, Chaowen; Tang, Jie; Shi, Dongfang

    2015-07-01

    Heat-labile enterotoxin (LT) of enterotoxigenic Escherichia coli (ETEC) is one of the major virulence factors for causing diarrhea in piglets, and LT is a strong immunogen. Thus, LT represents an important target for development of vaccines and diagnostic tests. In this study, bioinformatic tools were used to predict six antigenic B cell epitopes in the B subunit of LT protein (LTB) of ETEC strains. Then, seven antigenic B cell epitopes of LTB were identified by polyclonal antisera (polyclonal antibody (PAb)) using a set of LTB-derived peptides expressed as maltose-binding protein (MBP) fusion protein. In addition, one LTB-specific monoclonal antibody (MAb) was generated and defined its corresponding epitope as mentioned above. This MAb was able to specifically bind with native LT toxin and has no cross-reaction with LT-II (type II heat-labile enterotoxin), Stx1 (Shiga toxin I), Stx2 (Shiga toxin II), STa (heat-stable enterotoxin I), and STb (heat-stable enterotoxin II) toxins. Further, this MAb was able to interrupt LT toxin specific binding to GM1 receptor, indicating that the corresponding epitope is the specific binding region to GM1 receptor. Moreover, in vitro and in vivo assay showed that the MAb was able to neutralize the native LT toxin. Diarrheal suckling pigs challenged with LT-positive ETEC strain recovered when an enema with this purified MAb was administered. This study will provide the foundation for further studies about the interaction between LT toxin and GM1 receptor and about the developing of epitope-based vaccines and specific therapeutic agent. PMID:25794873

  6. Human Intestinal Epithelial Cells Swell and Demonstrate Actin Rearrangement in Response to the Metalloprotease Toxin ofBacteroides fragilis

    Microsoft Academic Search

    SHERIN S. KOSHY; MARSHALL H. MONTROSE; ANDCYNTHIA L. SEARS

    1996-01-01

    EnterotoxigenicBacteroides fragilis(ETBF) cells produce a 20-kDa heat-labile metalloprotease toxin which ispotentiallyimportantinthepathogenesisofdiarrheaassociatedwiththisinfection.Previousstudiesindicate that subconfluent HT29\\/C1 cells treated with the B. fragilis toxin (BFT) develop morphologic changes with dissolutionoftightclustersandapparentswelling.Suchalterationssuggesttoxin-stimulatedreorganizationof the cellular cytoskeleton. The purpose of the current study was to evaluate the effect of BFT on actin microfilaments(F-actin)andcellvolume.AsassessedbyfluorescentphallicidinstainingwhichdetectsF-actin, BFT treatment of HT29\\/C1 cells resulted in redistribution of F-actin with loss of stress

  7. Characteristics of the labile neurotoxin associated with nervous coccidiosis.

    PubMed

    Isler, C M; Bellamy, J E; Wobeser, G A

    1987-04-01

    Reported are the results of preliminary attempts to characterize the molecular weight, heat sensitivity and other features of a labile neurotoxin identified in the serum of calves exhibiting neurological signs in association with coccidial enteritis. The labile neurotoxin activity is heat labile (60 degrees C for 30 min) and is lost upon exposure to acidic pH (5.5) and cysteine (1.75 g/100 mL serum). Activity can be recovered from the precipitate of a 30% wt/vol solution of (NH4)2SO4 in serum. Ultrafiltration trials suggest that labile neurotoxin activity may be linked to a molecule of over 300,000 MW. PMID:2955866

  8. Rapid simultaneous ultrasensitive immunodetection of five bacterial toxins.

    PubMed

    Shlyapnikov, Yuri M; Shlyapnikova, Elena A; Simonova, Maria A; Shepelyakovskaya, Anna O; Brovko, Fedor A; Komaleva, Ravilya L; Grishin, Eugene V; Morozov, Victor N

    2012-07-01

    Rapid ultrasensitive detection of gastrointestinal pathogens presents a great interest for medical diagnostics and epidemiologic services. Though conventional immunochemical and polymerase chain reaction (PCR)-based methods are sensitive enough for many applications, they usually require several hours for assay, whereas as sensitive but more rapid methods are needed in many practical cases. Here, we report a new microarray-based analytical technique for simultaneous detection of five bacterial toxins: the cholera toxin, the E. coli heat-labile toxin, and three S. aureus toxins (the enterotoxins A and B and the toxic shock syndrome toxin). The assay involves three major steps: electrophoretic collection of toxins on an antibody microarray, labeling of captured antigens with secondary biotinylated antibodies, and detection of biotin labels by scanning the microarray surface with streptavidin-coated magnetic beads in a shear-flow. All the stages are performed in a single flow cell allowing application of electric and magnetic fields as well as optical detection of microarray-bound beads. Replacement of diffusion with a forced transport at all the recognition steps allows one to dramatically decrease both the limit of detection (LOD) and the assay time. We demonstrate here that application of this "active" assay technique to the detection of bacterial toxins in water samples from natural sources and in food samples (milk and meat extracts) allowed one to perform the assay in less than 10 min and to decrease the LOD to 0.1-1 pg/mL for water and to 1 pg/mL for food samples. PMID:22724559

  9. Microwave Heating Inactivates Shiga Toxin (Stx2) in Reconstituted Fat-Free Milk and Adversely Affects the Nutritional Value of Cell Culture Medium.

    PubMed

    Rasooly, Reuven; Hernlem, Bradley; He, Xiaohua; Friedman, Mendel

    2014-03-26

    Microwave exposure is a convenient and widely used method for defrosting, heating, and cooking numerous foods. Microwave cooking is also reported to kill pathogenic microorganisms that often contaminate food. In this study, we tested whether microwaves would inactivate the toxicity of Shiga toxin 2 (Stx2) added to 5% reconstituted fat-free milk administered to monkey kidney Vero cells. Heating of milk spiked with Stx2 in a microwave oven using a 10% duty cycle (cycle period of 30 s) for a total of 165 kJ energy or thermal heating (pasteurization), widely used to kill pathogenic bacteria, did not destroy the biological effect of the toxin in the Vero cells. However, conventional heating of milk to 95 °C for 5 min or at an increased microwave energy of 198 kJ reduced the Stx2 activity. Gel electrophoresis showed that exposure of the protein toxin to high-energy microwaves resulted in the degradation of its original structure. In addition, two independent assays showed that exposure of the cell culture medium to microwave energy of 198 kJ completely destroyed the nutritional value of the culture medium used to grow the Vero cells, possibly by damaging susceptible essential nutrients present in the medium. These observations suggest that microwave heating has the potential to destroy the Shiga toxin in liquid food. PMID:24669932

  10. Comparison of a live attenuated Salmonella Enteritidis vaccine candidate secreting Escherichia coli heat-labile enterotoxin B subunit with a commercial vaccine for efficacy of protection against internal egg contamination by Salmonella in hens.

    PubMed

    Nandre, Rahul M; Eo, Seong Kug; Park, Sang Youel; Lee, John Hwa

    2015-07-01

    This study compared a new live attenuated Salmonella Enteritidis vaccine candidate secreting Escherichia coli heat-labile enterotoxin B subunit (SE-LTB) with a commercial Salmonella Enteritidis (SE) vaccine for efficacy of protection against SE infection in laying hens. Chickens were divided into 3 groups of 20 each. Group A chickens were inoculated orally with phosphate-buffered saline and served as controls, group B chickens were inoculated orally with the vaccine candidate, and group C chickens were inoculated intramuscularly with a commercial vaccine, the primary inoculation in groups B and C being at 10 wk of age and the booster at 16 wk. Groups B and C showed significantly higher titers of plasma immunoglobulin G, intestinal secretory immunoglobulin A, and egg yolk immunoglobulin Y antibodies compared with the control group, and both vaccinated groups showed a significantly elevated cellular immune response. After virulent challenge, group B had significantly lower production of thin-shelled and/or malformed eggs and a significantly lower rate of SE contamination of eggs compared with the control group. Furthermore, the challenge strain was detected significantly less in all of the examined organs of group B compared with the control group. Group C had lower gross lesion scores only in the spleen and had lower bacterial counts only in the spleen, ceca, and ovary. These findings indicate that vaccination with the SE-LTB vaccine candidate can efficiently reduce internal egg and internal organ contamination by Salmonella and has advantages over the commercial vaccine. PMID:26130857

  11. Randomized clinical trial assessing the safety and immunogenicity of oral microencapsulated enterotoxigenic Escherichia coli surface antigen 6 with or without heat-labile enterotoxin with mutation R192G.

    PubMed

    Lapa, Joyce A; Sincock, Stephanie A; Ananthakrishnan, Madhumita; Porter, Chad K; Cassels, Frederick J; Brinkley, Carl; Hall, Eric R; van Hamont, John; Gramling, Joseph D; Carpenter, Colleen M; Baqar, S; Tribble, David R

    2008-08-01

    An oral, microencapsulated anti-colonization factor 6 antigen (meCS6) vaccine, with or without heat-labile enterotoxin with mutation R192G (LT(R192G)) (mucosal adjuvant), against enterotoxigenic Escherichia coli (ETEC) was evaluated for regimen and adjuvant effects on safety and immunogenicity. Sixty subjects were enrolled into a three-dose, 2-week interval or four-dose, 2-day interval regimen. Each regimen was randomized into two equal groups of meCS6 alone (1 mg) or meCS6 with adjuvant (2 microg of LT(R192G)). The vaccine was well tolerated and no serious adverse events were reported. Serologic response to CS6 was low in all regimens (0 to 27%). CS6-immunoglobulin A (IgA) antibody-secreting cell (ASC) responses ranged from 36 to 86%, with the highest level in the three-dose adjuvanted regimen; however, the magnitude was low. As expected, serologic and ASC LT responses were limited to adjuvanted regimens, with the exception of fecal IgA, which appeared to be nonspecific to LT administration. Further modifications to the delivery strategy and CS6 and adjuvant dose optimization will be needed before conducting further clinical trials with this epidemiologically important class of ETEC. PMID:18579693

  12. T cells reactive to an inducible heat shock protein induce disease in toxin-induced interstitial nephritis

    PubMed Central

    1994-01-01

    T cells reactive against immunodominant regions of inducible heat shock proteins (HSPs) have been identified in the chronic inflammatory lesions of several experimental autoimmune diseases. Since HSPs are known to be induced by a number of renal tubular epithelial cell toxins associated with chronic interstitial nephritis, we investigated the relevance of HSP expression and T cell reactivity to HSP70 in a model of progressive inflammatory interstitial nephritis. Chronic administration of cadmium chloride (CdCl2) to SJL/J mice induces HSP70 expression in renal tubular cells 4-5 wk before the development of interstitial mononuclear cell infiltrates. CdCl2 also induces HSP70 expression in cultured tubular epithelial cells from SJL/J mice. CD4+, TCR-alpha/beta+ T cell lines specific for an immunodominant HSP peptide are cytotoxic to heat stressed or CdCl2-treated renal tubular cells. Such HSP-reactive T cells mediate an inflammatory interstitial nephritis after adoptive transfer to CdCl2-treated mice at a time when immunoreactive HSP70 is detectable in the kidneys, but before the development of interstitial mononuclear cell infiltrates. T cells isolated from the nephritic kidneys of mice treated with CdCl2 for 13 wk are also cytotoxic to heat shocked or cadmium-treated tubular cells. These kidney-derived T cells additionally induced interstitial nephritis after passive transfer, indicating their pathogenic significance. Our studies strongly support a role for HSP-reactive T cells in CdCl2-induced interstitial nephritis and suggest that the induction of HSPs in the kidney by a multitude of "non-immune" events may initiate or facilitate inflammatory damage by HSP-reactive lymphocytes. PMID:7964497

  13. Thermal processing of labile materials: a kinetic approach

    Microsoft Academic Search

    D. H. Ziger; G. L. Wolk

    1988-01-01

    A simple Arrhenius approach to thermal processing of labile semiconductor resist materials is proposed which compensates for nonisothermal heat treatments, run-to-run thermal variations, and batch-loading effects. This technique was successfully used to control a photoresist resolution-enhancement process known as image reversal. By applying kinetic control to ammonia-catalyzed image-reversal processing, it was possible to extend minimum resolution to 0.5 ?m and

  14. Detection of proteinous toxins using the BioThreat Alert system, part 3: effects of heat pretreatment and interfering substances

    Microsoft Academic Search

    Yasuhiro Sano; Shigeharu Yamashiro; Asuka Komano; Hisashi Maruko; Hiroshi Sekiguchi; Yasuo Takayama; Ryoji Sekioka; Kouichiro Tsuge; Isaac Ohsawa; Mieko Kanamori-Kataoka; Yasuo Seto; Akiyoshi Satoh

    2007-01-01

    We previously reported that the Guardian Bio-Threat Alert (BTA) system could detect (detection limit: about 0.1 ?g\\/ml) staphylococcal\\u000a enterotoxin B (SEB), botulinum toxins (BTX) A and B, and ricin, with no interference by white-powdered materials or colored\\u000a matrices. In this study, the capability of the BTA system was further assessed. With 10 min of preheating at 60°C, all toxins\\u000a could

  15. Characterization of Immunological Cross-Reactivity between Enterotoxigenic Escherichia coli Heat-Stable Toxin and Human Guanylin and Uroguanylin

    PubMed Central

    Taxt, Arne M.; Diaz, Yuleima; Bacle, Amélie; Grauffel, Cédric; Reuter, Nathalie; Aasland, Rein; Sommerfelt, Halvor

    2014-01-01

    Enterotoxigenic Escherichia coli (ETEC) expressing the heat-stable toxin (ST) (human-type [STh] and porcine-type [STp] variants) is among the five most important enteric pathogens in young children living in low- and middle-income countries. ST mediates diarrheal disease through activation of the guanylate cyclase C (GC-C) receptor and is an attractive vaccine target with the potential to confer protection against a wide range of ETEC strains. However, immunological cross-reactivity to the endogenous GC-C ligands guanylin and uroguanylin is a major concern because of the similarities to ST in amino acid sequence, structure, and function. We have investigated the presence of similar epitopes on STh, STp, guanylin, and uroguanylin by analyzing these peptides in eight distinct competitive enzyme-linked immunosorbent assays (ELISAs). A fraction (27%) of a polyclonal anti-STh antibody and an anti-STh monoclonal antibody (MAb) cross-reacted with uroguanylin, the latter with a 73-fold-lower affinity. In contrast, none of the antibodies raised against STp, one polyclonal antibody and three MAbs, cross-reacted with the endogenous peptides. Antibodies raised against guanylin and uroguanylin showed partial cross-reactivity with the ST peptides. Our results demonstrate, for the first time, that immunological cross-reactions between ST and the endogenous peptides can occur. However, the partial nature and low affinity of the observed cross-reactions suggest that the risk of adverse effects from a future ST vaccine may be low. Furthermore, our results suggest that this risk may be reduced or eliminated by basing an ST immunogen on STp or a selectively mutated variant of STh. PMID:24778111

  16. Intradermal Administration of the Type II Heat-Labile Enterotoxins LT-IIb and LT-IIc of Enterotoxigenic Escherichia coli Enhances Humoral and CD8+ T Cell Immunity to a Co-Administered Antigen

    PubMed Central

    Hu, John C.; Mathias-Santos, Camila; Greene, Christopher J.; King-Lyons, Natalie D.; Rodrigues, Juliana F.; Hajishengallis, George; Ferreira, Luís C. S.; Connell, Terry D.

    2014-01-01

    Vaccinations are extremely effective at combating infectious diseases. Many conserved antigen (Ag) targets, however, are poorly immunogenic. Protein subunit vaccines frequently elicit only humoral immune responses and fail to confer protection against serious intracellular pathogens. These barriers to vaccine development are often overcome by the use of appropriate adjuvants. Heat-labile enterotoxins (HLT) produced by enterotoxigenic strains of Escherichia coli are potent adjuvants when administered by mucosal or systemic routes. The efficacy of the type II HLT, however, has not been well-defined when administered by the intradermal (ID) route. Using a murine ID immunization model, the adjuvant properties of LT-IIb and LT-IIc, two type II HLTs, were compared with those of LT-I, a prototypical type I HLT. While all three HLT adjuvants enhanced Ag-specific humoral responses to similar levels, LT-IIb and LT-IIc, in contrast to LT-I, induced a more vigorous Ag-specific CD8+ T cell response and proffered faster clearance of Listeria monocytogenes in a challenge model. Additionally, LT-IIb and LT-IIc induced distinct differences in the profiles of the Ag-specific CD8+ T cell responses. While LT-IIc stimulated a robust and rapid primary CD8+ T cell response, LT-IIb exhibited slower CD8+ T cell expansion and contraction kinetics with the formation of higher percentages of effector memory cells. In comparison to LT-I and LT-IIc, LT-IIb evoked better long-term protection after immunization. Furthermore, LT-IIb and LT-IIc enhanced the total number of dendritic cells (DC) in the draining lymph node (DLN) and expression of costimulatory molecules CD80, CD86, and CD40 on DCs. In contrast to LT-I, LT-IIb and LT-IIc induced less edema, cellular infiltrates, and general inflammation at the site of ID injection. Thus, LT-IIb and LT-IIc are attractive comprehensive ID adjuvants with unique characteristic that enhance humoral and cellular immunity to a co-administered protein Ag. PMID:25536061

  17. Novel Proteinaceous Toxins from the Box Jellyfish (Sea Wasp) Carybdea rastoni

    Microsoft Academic Search

    Hiroshi Nagai; Kyoko Takuwa; Masahiro Nakao; Emiko Ito; Masami Miyake; Masatoshi Noda; Terumi Nakajima

    2000-01-01

    During summer and autumn, the box jellyfish (sea wasp) Carybdea rastoni is one of the most bothersome stinging pests to swimmers and bathers on the Japanese coast. Two labile but potent hemolytic toxins from the tentacles of Carybdea rastoni were isolated in their active forms using newly developed purification methods. The molecular masses of the isolated C. rastoni toxin-A and

  18. Mucosal adjuvants and anti-infection and anti-immunopathology vaccines based on cholera toxin, cholera toxin B subunit and CpG DNA.

    PubMed

    Holmgren, Jan; Harandi, Ali M; Czerkinsky, Cecil

    2003-04-01

    The mucosal immune system consists of an integrated network of lymphoid cells that work in concert with innate host factors to promote host defence. Mucosal immunization can be used both to protect the mucosal surfaces against colonization and invasion by microbial pathogens and to provide a means for immunological treatment of selected autoimmune, allergic or infectious-immunopathological disorders through the induction of antigen-specific tolerance. The development of mucosal vaccines, whether for prevention of infectious diseases or for oral tolerance immunotherapy, requires efficient antigen delivery and adjuvant systems. Significant progress has recently been made to generate partly or wholly detoxified derivatives of cholera toxin (including the completely nontoxic cholera toxin B subunit) and the closely related Escherichia coli heat-labile enterotoxin, with retained adjuvant activity. Cholera toxin B subunit is a protective component of a widely registered oral vaccine against cholera, and has proven to be a promising vector for either giving rise to anti-infective immunity or for inducing peripheral anti-inflammatory tolerance to chemically or genetically linked foreign antigens administered mucosally. Promising advances have also recently been made in the design of efficient mucosal adjuvants based on bacterial DNA that contains CpG-motifs and various imidazoquinoline compounds binding to different Toll-like receptors on mucosal antigen-presenting cells. PMID:12899572

  19. Botulinum Toxin Therapy

    MedlinePLUS

    ... Z Diseases and treatments A - D Botulinum toxin Botulinum toxin therapy Also called botulinum rejuvenation Brand names: Botox® ... out what your policy covers. Learn more about botulinum toxin therapy: Is botulinum toxin therapy the right choice ...

  20. BOTULINUM TOXIN

    PubMed Central

    Nigam, P K; Nigam, Anjana

    2010-01-01

    Botulinum toxin, one of the most poisonous biological substances known, is a neurotoxin produced by the bacterium Clostridium botulinum. C. botulinum elaborates eight antigenically distinguishable exotoxins (A, B, C1, C2, D, E, F and G). All serotypes interfere with neural transmission by blocking the release of acetylcholine, the principal neurotransmitter at the neuromuscular junction, causing muscle paralysis. The weakness induced by injection with botulinum toxin A usually lasts about three months. Botulinum toxins now play a very significant role in the management of a wide variety of medical conditions, especially strabismus and focal dystonias, hemifacial spasm, and various spastic movement disorders, headaches, hypersalivation, hyperhidrosis, and some chronic conditions that respond only partially to medical treatment. The list of possible new indications is rapidly expanding. The cosmetological applications include correction of lines, creases and wrinkling all over the face, chin, neck, and chest to dermatological applications such as hyperhidrosis. Injections with botulinum toxin are generally well tolerated and side effects are few. A precise knowledge and understanding of the functional anatomy of the mimetic muscles is absolutely necessary to correctly use botulinum toxins in clinical practice. PMID:20418969

  1. Anthrax toxins.

    PubMed

    Mourez, M

    2004-01-01

    Bacillus anthracis, the etiological agent of anthrax, secretes three polypeptides that assemble into toxic complexes on the cell surfaces of the host it infects. One of these polypeptides, protective antigen (PA), binds to the integrin-like domains of ubiquitously expressed membrane proteins of mammalian cells. PA is then cleaved by membrane endoproteases of the furin family. Cleaved PA molecules assemble into heptamers, which can then associate with the two other secreted polypeptides: edema factor (EF) and/or lethal factor (LF). The heptamers of PA are relocalized to lipid rafts where they are quickly endocytosed and routed to an acidic compartment. The low pH triggers a conformational change in the heptamers, resulting in the formation of cation-specific channels and the translocation of EF/LF. EF is a calcium- and calmodulin-dependent adenylate cyclase that dramatically raises the intracellular concentration of cyclic adenosine monophosphate (cAMP). LF is a zinc-dependent endoprotease that cleaves the amino terminus of mitogen-activated protein kinase kinases (Meks). Cleaved Meks cannot bind to their substrates and have reduced kinase activity, resulting in alterations of the signaling pathways they govern. The structures of PA, PA heptamer, EF, and LF have been solved and much is now known about the molecular details of the intoxication mechanism. The in vivo action of the toxins, on the other hand, is still poorly understood and hotly debated. A better understanding of the toxins will help in the design of much-needed anti-toxin drugs and the development of new toxin-based medical applications. PMID:15549606

  2. Development of an immunochromatographic test strip for detection of cholera toxin.

    PubMed

    Yamasaki, Eiki; Sakamoto, Ryuta; Matsumoto, Takashi; Morimatsu, Fumiki; Kurazono, Takayuki; Hiroi, Toyoko; Nair, G Balakrish; Kurazono, Hisao

    2013-01-01

    Because cholera toxin (CT) is responsible for most of the symptoms induced by Vibrio cholerae infection, detection of CT is critical for diagnosis of the disease. In this study, we constructed an immunochromatographic test strip for detection of CT (CT-IC) with polyclonal antibodies developed against purified recombinant whole CT protein. The detection limit of the CT-IC was 10 ng/mL of purified recombinant CT, and it could detect the CT in culture supernatant of all 15 toxigenic V. cholerae isolates examined, whereas no false-positive signal was detected in all 5 nontoxigenic V. cholerae isolates examined. The specificity of the CT-IC was examined with recombinant heat-labile toxin (LT), which shares high homology with CT, and it was revealed that the minimum detection limit for LT was 100 times higher than that for CT. In addition, lt gene-positive enterotoxigenic Escherichia coli (ETEC) was examined by CT-IC. The false-positive signals were observed in 3 out of 12 ETEC isolates, but these signals were considerably faint. The CT-IC did not develop false-positive signals with all 7 V. parahaemolyticus isolates. These results showed the high specificity of CT-IC and the feasible use of it for the detection and surveillance of toxigenic V. cholerae. PMID:24308002

  3. Development of an Immunochromatographic Test Strip for Detection of Cholera Toxin

    PubMed Central

    Yamasaki, Eiki; Sakamoto, Ryuta; Matsumoto, Takashi; Morimatsu, Fumiki; Kurazono, Takayuki; Hiroi, Toyoko; Nair, G. Balakrish; Kurazono, Hisao

    2013-01-01

    Because cholera toxin (CT) is responsible for most of the symptoms induced by Vibrio cholerae infection, detection of CT is critical for diagnosis of the disease. In this study, we constructed an immunochromatographic test strip for detection of CT (CT-IC) with polyclonal antibodies developed against purified recombinant whole CT protein. The detection limit of the CT-IC was 10?ng/mL of purified recombinant CT, and it could detect the CT in culture supernatant of all 15 toxigenic V. cholerae isolates examined, whereas no false-positive signal was detected in all 5 nontoxigenic V. cholerae isolates examined. The specificity of the CT-IC was examined with recombinant heat-labile toxin (LT), which shares high homology with CT, and it was revealed that the minimum detection limit for LT was 100 times higher than that for CT. In addition, lt gene-positive enterotoxigenic Escherichia coli (ETEC) was examined by CT-IC. The false-positive signals were observed in 3 out of 12 ETEC isolates, but these signals were considerably faint. The CT-IC did not develop false-positive signals with all 7 V. parahaemolyticus isolates. These results showed the high specificity of CT-IC and the feasible use of it for the detection and surveillance of toxigenic V. cholerae. PMID:24308002

  4. Biologically labile photoproducts from riverine non-labile dissolved organic carbon in the coastal waters

    NASA Astrophysics Data System (ADS)

    Kasurinen, V.; Aarnos, H.; Vähätalo, A.

    2015-06-01

    In order to assess the production of biologically labile photoproducts (BLPs) from non-labile riverine dissolved organic carbon (DOC), we collected water samples from ten major rivers, removed labile DOC and mixed the residual non-labile DOC with artificial seawater for microbial and photochemical experiments. Bacteria grew on non-labile DOC with a growth efficiency of 11.5% (mean; range from 3.6 to 15.3%). Simulated solar radiation transformed a part of non-labile DOC into BLPs, which stimulated bacterial respiration and production, but did not change bacterial growth efficiency (BGE) compared to the non-irradiated dark controls. In the irradiated water samples, the amount of BLPs stimulating bacterial production depended on the photochemical bleaching of chromophoric dissolved organic matter (CDOM). The apparent quantum yields for BLPs supporting bacterial production ranged from 9.5 to 76 (mean 39) (?mol C mol photons-1) at 330 nm. The corresponding values for BLPs supporting bacterial respiration ranged from 57 to 1204 (mean 320) (?mol C mol photons-1). According to the calculations based on spectral apparent quantum yields and local solar radiation, the annual production of BLPs ranged from 21 (St. Lawrence) to 584 (Yangtze) mmol C m-2 yr-1 in the plumes of the examined rivers. Complete photobleaching of riverine CDOM in the coastal ocean was estimated to produce 10.7 Mt C BLPs yr-1 from the rivers examined in this study and globally 38 Mt yr-1 (15% of riverine DOC flux from all rivers), which support 4.1 Mt yr-1 of bacterial production and 33.9 Mt yr-1 bacterial respiration.

  5. Cholera toxin-like toxin released by Salmonella species in the presence of mitomycin C.

    PubMed Central

    Molina, N C; Peterson, J W

    1980-01-01

    Several serotypes of Salmonella were shown to release increased amounts of a cholera toxin-like toxin during culture in vitro with mitomycin C (MTC). Filter-sterilized culture supernatants containing the toxin caused elongation of Chinese hamster ovary cells, which could be blocked by heating the supernatants at 100 degrees C for 15 min or by adding mixed gangliosides or monospecific cholera antitoxin. When MTC was not added to the Salmonella cultures, little or no toxin was detected in crude, unconcentrated culture supernatants. Optimal production of toxin was observed in the presence of 0.5 micrograms of MTC per ml in shake flask cultures of Casamino Acids-yeast extract medium, Syncase, or peptone saline at 37 degrees C. Meat infusion media (heart infusion and brain heart infusion) plus MTC resulted in poor toxin yield. Culture filtrates frequently could be diluted 1:8 and still result in elongation of Chinese hamster ovary cells. Images Fig. 1 PMID:7002788

  6. Fate and lability of silver in soils: Effect of ageing

    EPA Science Inventory

    The fate and lability of added soluble Ag in soils over time was examined by measurement of labile metal (E-value) by isotopic dilution using the 110mAg radioactive isotope and the solid-phase speciation of Ag by X-ray absorption near edge structure (XANES) spectrosco...

  7. A biomarker for the identification of cattle fecal pollution in water using the LTIIa toxin gene from enterotoxigenic Escherichia coli.

    PubMed

    Khatib, L A; Tsai, Y L; Olson, B H

    2002-06-01

    This research describes a method based on PCR to identify cattle fecal pollution in water using a portion of the heat labile toxin IIA (LTIIa) gene from enterotoxigenic Escherichia coli (ETEC). We describe the development of the primers and target. DNA extracts (221) from different animal fecal and human sewage samples were screened and showed no cross-reactivity. Minimum detection limits using centrifugation and filtration methods to concentrate E. coli seeded into stream, ocean, and secondary effluent waters were found to be at femtogram and attogram levels, respectively. Stability of the biomarker in stream, ocean, and secondary effluent waters was 2-4 weeks for all water types. Finally, 33 farm lagoon and waste samples were collected and 31 tested to validate the method; 93% were positive for the LTIIa trait when >1,000 E. coli were screened and 100% positive when >10(5) E. coli were screened. Prevalence of the toxin gene in the E. coli population affected the outcome of the analyses. The cow biomarker can be used in watershed studies to identify cattle waste with great accuracy if the appropriate numbers of E. coli are screened. PMID:12073139

  8. Anthrax toxin receptor proteins

    Microsoft Academic Search

    Kenneth A. Bradley; John A. T. Young

    2003-01-01

    Anthrax toxin is a key virulence factor for Bacillus anthracis, the causative agent of anthrax. Here we discuss what is known about the anthrax toxin receptor (ATR), the cellular receptor for anthrax toxin, and how this information is being used to develop treatments for anthrax as well as to understand aspects of cancer. ATR was identified recently as a type

  9. Toxines botuliques : utilisation pratique

    Microsoft Academic Search

    A Durand; G Serment

    2003-01-01

    Botulinum toxins (A and B) are neurotoxins derived from Clostridium botulinum. Clostridium are anaerobic bacteria. C. botulinum produces exotoxins (A to G) with distinct antigenicities. The neurotoxins inhibit the release of the neurotransmitter acetylcholine from the axon terminals of motor neurons. Botulinum toxin is officially used in clinic for the treatment of muscular hyperactivity (strabismus, blepharospam, cervical dystonia). Botulinum toxins

  10. Functional and Structural Insights of a Staphylococcus aureus Apoptotic-like Membrane Peptide from a Toxin-Antitoxin

    E-print Network

    Rennes, Université de

    Functional and Structural Insights of a Staphylococcus aureus Apoptotic-like Membrane Peptide from of Staphylococcus aureus, has been solved. Conclusion: S. aureus has a functional type I TA system that induces, Staphylococcus aureus. TA sys- tems consist of stable toxins and labile antitoxins encoded within small genetic

  11. Practical use of labile protein as an index of hair.

    PubMed

    Inoue, Takafumi; Kizawa, Kenji; Ito, Mayumi; Shinkai, Masakazu; Iwamoto, Yoshimichi

    2004-01-01

    Because of small fluctuations, it is difficult to evaluate hair damage caused by bleaching using previously utilized hair damage indexes. Application of commercial bleaching products elevates partially extractable labile hair protein amounts in the range of 0.4-1.2 mg/g of hair. Within this range, the level of labile protein fluctuates greatly, depending on the extent of bleaching. In the current study, it was found that the effects of alkaline constituents and various peptides contained in bleaching lotions on hair damage could be evaluated by measuring labile protein amounts without employing harsher bleaching conditions. PMID:15645111

  12. Bioterrorism: toxins as weapons.

    PubMed

    Anderson, Peter D

    2012-04-01

    The potential for biological weapons to be used in terrorism is a real possibility. Biological weapons include infectious agents and toxins. Toxins are poisons produced by living organisms. Toxins relevant to bioterrorism include ricin, botulinum, Clostridium perfrigens epsilson toxin, conotoxins, shigatoxins, saxitoxins, tetrodotoxins, mycotoxins, and nicotine. Toxins have properties of biological and chemical weapons. Unlike pathogens, toxins do not produce an infection. Ricin causes multiorgan toxicity by blocking protein synthesis. Botulinum blocks acetylcholine in the peripheral nervous system leading to muscle paralysis. Epsilon toxin damages cell membranes. Conotoxins block potassium and sodium channels in neurons. Shigatoxins inhibit protein synthesis and induce apoptosis. Saxitoxin and tetrodotoxin inhibit sodium channels in neurons. Mycotoxins include aflatoxins and trichothecenes. Aflatoxins are carcinogens. Trichothecenes inhibit protein and nucleic acid synthesis. Nicotine produces numerous nicotinic effects in the nervous system. PMID:22523138

  13. Conformational Instability of the Cholera Toxin A1 Polypeptide

    PubMed Central

    Pande, Abhay H.; Scaglione, Patricia; Taylor, Michael; Nemec, Kathleen N.; Tuthill, Summer; Moe, David; Holmes, Randall K.; Tatulian, Suren A.; Teter, Ken

    2007-01-01

    Summary Cholera toxin (CT) moves from the cell surface to the endoplasmic reticulum (ER) by vesicular transport. In the ER, the catalytic CTA1 subunit dissociates from the holotoxin and enters the cytosol by exploiting the quality control system of ER-associated degradation (ERAD). It is hypothesized that CTA1 triggers its ERAD-mediated translocation into the cytosol by masquerading as a misfolded protein, but the process by which CTA1 activates the ERAD system remains unknown. Here, we directly assess the thermal stability of the isolated CTA1 polypeptide by biophysical and biochemical methods and correlate its temperature-dependent conformational state with susceptibility to degradation by the 20S proteasome. Measurements with circular dichroism and fluorescence spectroscopy demonstrated that CTA1 is a thermally unstable protein with a disordered tertiary structure and a disturbed secondary structure at 37°C. A protease sensitivity assay likewise detected the temperature-induced loss of native CTA1 structure. This protease-sensitive conformation was not apparent when CTA1 remained covalently associated with the CTA2 subunit. Thermal instability in the dissociated CTA1 polypeptide could thus allow it to appear as a misfolded protein for ERAD-mediated export to the cytosol. In vitro, the disturbed conformation of CTA1 at 37°C rendered it susceptible to ubiquitin-independent degradation by the core 20S proteasome. In vivo, CTA1 was also susceptible to degradation by a ubiquitin-independent proteasomal mechanism. ADP-ribosylation factor 6, a cytosolic eukaryotic protein that enhances the enzymatic activity of CTA1, stabilized the heat-labile conformation of CTA1 and protected it from in vitro degradation by the 20S proteasome. Thermal instability in the reduced CTA1 polypeptide has not been reported before, yet both the translocation and degradation of CTA1 may depend upon this physical property. PMID:17976649

  14. Nanoparticle-detained toxins for safe and effective vaccination

    NASA Astrophysics Data System (ADS)

    Hu, Che-Ming J.; Fang, Ronnie H.; Luk, Brian T.; Zhang, Liangfang

    2013-12-01

    Toxoid vaccines--vaccines based on inactivated bacterial toxins--are routinely used to promote antitoxin immunity for the treatment and prevention of bacterial infections. Following chemical or heat denaturation, inactivated toxins can be administered to mount toxin-specific immune responses. However, retaining faithful antigenic presentation while removing toxin virulence remains a major challenge and presents a trade-off between efficacy and safety in toxoid development. Here, we show a nanoparticle-based toxin-detainment strategy that safely delivers non-disrupted pore-forming toxins for immune processing. Using erythrocyte membrane-coated nanoparticles and staphylococcal ?-haemolysin, we demonstrate effective virulence neutralization via spontaneous particle entrapment. Compared with vaccination with heat-denatured toxin, mice vaccinated with the nanoparticle-detained toxin showed superior protective immunity against toxin-mediated adverse effects. We find that the non-disruptive detoxification approach benefited the immunogenicity and efficacy of toxoid vaccines. We anticipate that this study will open new possibilities in the preparation of antitoxin vaccines against the many virulence factors that threaten public health.

  15. Evaluation of heavy metal lability in polluted soils by a cation exchange batch procedure.

    PubMed

    Esnaola, M V; Millán, E

    1998-01-01

    A new extraction procedure with cationic exchange resins is proposed for the assessment of heavy metal lability in polluted soils. This method classifies soluble metal compounds in three levels according to their lability: very labile, moderately labile and non-labile. The concept of lability is based on the use of resins with different ability to interact with metals. The proposed procedure was applied to five samples of polluted soils. In the five soils, soluble Cd was found to be very labile, soluble Ni and Pb were mostly non-labile, Mn and Zn lability depended on the soil, while Cu had a fraction of moderately labile forms in four of the five soils. The resin extraction procedure was compared with the DTPA and CaCl2 extractions. PMID:15093332

  16. Toxin–antitoxin systems

    PubMed Central

    Unterholzner, Simon J; Poppenberger, Brigitte; Rozhon, Wilfried

    2013-01-01

    Toxin–antitoxin (TA) systems are small genetic elements composed of a toxin gene and its cognate antitoxin. The toxins of all known TA systems are proteins while the antitoxins are either proteins or non-coding RNAs. Based on the molecular nature of the antitoxin and its mode of interaction with the toxin the TA modules are currently grouped into five classes. In general, the toxin is more stable than the antitoxin but the latter is expressed to a higher level. If supply of the antitoxin stops, for instance under special growth conditions or by plasmid loss in case of plasmid encoded TA systems, the antitoxin is rapidly degraded and can no longer counteract the toxin. Consequently, the toxin becomes activated and can act on its cellular targets. Typically, TA toxins act on crucial cellular processes including translation, replication, cytoskeleton formation, membrane integrity, and cell wall biosynthesis. TA systems and their components are also versatile tools for a multitude of purposes in basic research and biotechnology. Currently, TA systems are frequently used for selection in cloning and for single protein expression in living bacterial cells. Since several TA toxins exhibit activity in yeast and mammalian cells they may be useful for applications in eukaryotic systems. TA modules are also considered as promising targets for the development of antibacterial drugs and their potential to combat viral infection may aid in controlling infectious diseases. PMID:24251069

  17. Botulinum toxin injection - larynx

    MedlinePLUS

    Injection laryngoplasty; Botox-larynx: spasmodic dysphonia-BTX; Essential voice tremor (EVT)-btx; Glottic insufficiency; Percutaneous electromyography-guided botulinum toxin treatment; Percutaneous indirect laryngoscopy- ...

  18. Fate and lability of silver in soils: effect of ageing.

    PubMed

    Settimio, Lara; McLaughlin, Mike J; Kirby, Jason K; Langdon, Kate A; Lombi, Enzo; Donner, Erica; Scheckel, Kirk G

    2014-08-01

    The fate and lability of added soluble Ag in soils over time was examined by measurement of labile metal (E-value) by isotopic dilution using the (110m)Ag radioactive isotope and the solid-phase speciation of Ag by X-ray absorption near edge structure (XANES) spectroscopy. After two weeks of ageing the E-values for Ag decreased by 20-90% with a further decrease of 10-40% after six months. The overall decrease in labile Ag for all soils after the 6 month ageing period was 50-100%. The ageing was more rapid and pronounced in the alkaline soils. XANES results for Ag in soils indicated that for the majority of soils the added Ag(+) was reduced to metallic Ag over time, and associations with Fe-oxohydroxides and reduced S groups in organic matter also decreased Ag lability. Strong positive correlations were found between metallic Ag and non-labile Ag and between organic carbon and Ag bonded with S species. PMID:24836503

  19. Anthrax Toxin Receptor 2Dependent Lethal Toxin Killing In Vivo

    E-print Network

    Sejnowski, Terrence J.

    Anthrax Toxin Receptor 2­Dependent Lethal Toxin Killing In Vivo Heather M. Scobie1,2 , Darran J Jolla, California, United States of America Anthrax toxin receptors 1 and 2 (ANTXR1 and ANTXR2) have by residue D683 of the protective antigen (PA) subunit of anthrax toxin. The receptor-bound metal ion and PA

  20. Animal toxins and the kidney

    Microsoft Academic Search

    Visith Sitprija

    2008-01-01

    Envenomation or poisoning by toxins from animals poses an important health hazard in the tropics. Animal toxins are complex mixtures of proteins, peptides, enzymes and chemicals. These toxins exert their effects through modulation of ion channels and receptors, and via direct enzyme action. Depolarization or hyperpolarization of ion channels—caused by most marine toxins, and some snake and insect venoms—results in

  1. Microorganisms and microbial toxins.

    PubMed

    Reid, D S; Harris, L J

    1999-01-01

    The primary concern in food safety issues focuses on microorganisms and microbial toxins. Effective food preservation requires that the growth and proliferation of hazardous microorganisms be well controlled, and that the presence of significant quantities of microbial toxins in foods be prevented. The traditional effective preservation methodologies, such as canning, are being supplemented by new technologies which are less destructive of the food qualities. New strategies are therefore needed to prevent the transmission of microbial contamination or to prevent the formation of microbial toxins which remain in food. This paper discusses the role of modern processing methodologies in helping protect consumers from hazards of microbial origin. PMID:10335366

  2. cAMP imaging of cells treated with pertussis toxin, cholera toxin, and anthrax edema toxin

    Microsoft Academic Search

    Federica Dal Molin; Irene Zornetta; Andrea Puhar; Fiorella Tonello; Manuela Zaccolo; Cesare Montecucco

    2008-01-01

    The enzymatic activity of the three most studied bacterial toxins that increase the cytosolic cAMP level: pertussis toxin (PT), cholera toxin (CT), and anthrax edema toxin (ET), was imaged by fluorescence videomicroscopy. Three different cell lines were transfected with a fluorescence resonance energy transfer biosensor based on the PKA regulatory and catalytic subunits fused to CFP and YFP, respectively. Real-time

  3. Application of a chemical leach technique for estimating labile particulate aluminum, iron, and manganese in the Columbia River plume and coastal waters off Oregon and Washington

    NASA Astrophysics Data System (ADS)

    Berger, Carolyn J. M.; Lippiatt, Sherry M.; Lawrence, Michael G.; Bruland, Kenneth W.

    2008-02-01

    In order to determine the total concentration of bioavailable trace metals in seawater, measurement of both the dissolved and labile particulate fractions is necessary. Comparison of labile particulate metal concentrations from various researchers is limited because of differing definitions of the fraction that is potentially available to phytoplankton on a time frame of generations. A comparison experiment was conducted on coastal and riverine suspended particulate matter to determine the difference between several commonly used techniques that operationally define the labile particulate trace metal fraction. Furthermore, we compared two leach techniques for surface transect samples from within the Columbia River plume and water offshore of Oregon and Washington, United States. The particulate trace metal concentration in the leachate was determined by high-resolution inductively coupled plasma-mass spectrometry. From this comparison, one chemical leach was chosen to best define the labile particulate fraction of Al, Fe, and Mn: a weak acid leach (25% acetic acid at pH 2) with a mild reducing agent (0.02 M hydroxylamine hydrochloride) and a short heating step (10 min 90-95°C). This leach was applied to three surface transects within the Columbia River plume. These coastal waters were found to be rich in labile particulate trace metals that are directly delivered from the Columbia River and indirectly supplied via resuspension from upwelling over a broad continental shelf.

  4. Targeted Silencing of Anthrax Toxin Receptors Protects against Anthrax Toxins*

    PubMed Central

    Arévalo, Maria T.; Navarro, Ashley; Arico, Chenoa D.; Li, Junwei; Alkhatib, Omar; Chen, Shan; Diaz-Arévalo, Diana; Zeng, Mingtao

    2014-01-01

    Anthrax spores can be aerosolized and dispersed as a bioweapon. Current postexposure treatments are inadequate at later stages of infection, when high levels of anthrax toxins are present. Anthrax toxins enter cells via two identified anthrax toxin receptors: tumor endothelial marker 8 (TEM8) and capillary morphogenesis protein 2 (CMG2). We hypothesized that host cells would be protected from anthrax toxins if anthrax toxin receptor expression was effectively silenced using RNA interference (RNAi) technology. Thus, anthrax toxin receptors in mouse and human macrophages were silenced using targeted siRNAs or blocked with specific antibody prior to challenge with anthrax lethal toxin. Viability assays were used to assess protection in macrophages treated with specific siRNA or antibody as compared with untreated cells. Silencing CMG2 using targeted siRNAs provided almost complete protection against anthrax lethal toxin-induced cytotoxicity and death in murine and human macrophages. The same results were obtained by prebinding cells with specific antibody prior to treatment with anthrax lethal toxin. In addition, TEM8-targeted siRNAs also offered significant protection against lethal toxin in human macrophage-like cells. Furthermore, silencing CMG2, TEM8, or both receptors in combination was also protective against MEK2 cleavage by lethal toxin or adenylyl cyclase activity by edema toxin in human kidney cells. Thus, anthrax toxin receptor-targeted RNAi has the potential to be developed as a life-saving, postexposure therapy against anthrax. PMID:24742682

  5. Naturally Occurring Food Toxins

    PubMed Central

    Dolan, Laurie C.; Matulka, Ray A.; Burdock, George A.

    2010-01-01

    Although many foods contain toxins as a naturally-occurring constituent or, are formed as the result of handling or processing, the incidence of adverse reactions to food is relatively low. The low incidence of adverse effects is the result of some pragmatic solutions by the US Food and Drug Administration (FDA) and other regulatory agencies through the creative use of specifications, action levels, tolerances, warning labels and prohibitions. Manufacturers have also played a role by setting limits on certain substances and developing mitigation procedures for process-induced toxins. Regardless of measures taken by regulators and food producers to protect consumers from natural food toxins, consumption of small levels of these materials is unavoidable. Although the risk for toxicity due to consumption of food toxins is fairly low, there is always the possibility of toxicity due to contamination, overconsumption, allergy or an unpredictable idiosyncratic response. The purpose of this review is to provide a toxicological and regulatory overview of some of the toxins present in some commonly consumed foods, and where possible, discuss the steps that have been taken to reduce consumer exposure, many of which are possible because of the unique process of food regulation in the United States. PMID:22069686

  6. Naturally occurring food toxins.

    PubMed

    Dolan, Laurie C; Matulka, Ray A; Burdock, George A

    2010-09-01

    Although many foods contain toxins as a naturally-occurring constituent or, are formed as the result of handling or processing, the incidence of adverse reactions to food is relatively low. The low incidence of adverse effects is the result of some pragmatic solutions by the US Food and Drug Administration (FDA) and other regulatory agencies through the creative use of specifications, action levels, tolerances, warning labels and prohibitions. Manufacturers have also played a role by setting limits on certain substances and developing mitigation procedures for process-induced toxins. Regardless of measures taken by regulators and food producers to protect consumers from natural food toxins, consumption of small levels of these materials is unavoidable. Although the risk for toxicity due to consumption of food toxins is fairly low, there is always the possibility of toxicity due to contamination, overconsumption, allergy or an unpredictable idiosyncratic response. The purpose of this review is to provide a toxicological and regulatory overview of some of the toxins present in some commonly consumed foods, and where possible, discuss the steps that have been taken to reduce consumer exposure, many of which are possible because of the unique process of food regulation in the United States. PMID:22069686

  7. Labile products of interaction of cellulose with nitrogen oxide compounds

    NASA Astrophysics Data System (ADS)

    Gert, Evgenii V.

    1997-01-01

    Data concerning the conditions and kinetics of the formation, the methods for identification and isolation, the chemical and physical properties, and the crystal structure of cellulose trinitrite are presented. The conditions governing the formation of Knecht' sorption compound and other unstable crystalline products in the cellulose-N2O4 system are also discussed. The primary role of labile derivatives in the manifestation of polymorphism by cellulose on its regeneration from these compounds is demonstrated. The causes of the amorphisation of cellulose, which may occur in these systems, are examined. Examples of a rational combination of several functions of the reaction medium and of the labile nitrogen-containing compound present in it in the preparation of other materials of practical importance from polysaccharides (sulfate and acetate esters and structurally and chemically modified powdered forms of cellulose) are presented. The bibliography includes 160 references.

  8. Paralytic shellfish toxins inhibit copper uptake in Chlamydomonas reinhardtii.

    PubMed

    Cusick, Kathleen D; Wetzel, Randall K; Minkin, Steven C; Dodani, Sheel C; Wilhelm, Steven W; Sayler, Gary S

    2013-06-01

    Paralytic shellfish toxins are secondary metabolites produced by several species of dinoflagellates and cyanobacteria. Known targets of these toxins, which typically occur at detrimental concentrations during harmful algal blooms, include voltage-gated ion channels in humans and other mammals. However, the effects of the toxins on the co-occurring phytoplankton community remain unknown. The present study examined the molecular mechanisms of the model photosynthetic alga Chlamydomonas reinhardtii in response to saxitoxin exposure as a means of gaining insight into the phytoplankton community response to a bloom. Previous work with yeast indicated that saxitoxin inhibited copper uptake, so experiments were designed to examine whether saxitoxin exhibited a similar mode of action in algae. Expression profiling following exposure to saxitoxin or a copper chelator produced similar profiles in copper homeostasis genes, notably induction of the cytochrome c6 (CYC6) and copper transporter (COPT1, CTR1) genes. Cytochrome c6 is used as an alternative to plastocyanin under conditions of copper deficiency, and immunofluorescence data showed this protein to be present in a significantly greater proportion of saxitoxin-exposed cells compared to controls. Live-cell imaging with a copper-sensor probe for intracellular labile Cu(I) confirmed that saxitoxin blocked copper uptake. Extrapolations of these data to phytoplankton metabolic processes along with the copper transporter as a molecular target of saxitoxin based on existing structural models are discussed. PMID:23423950

  9. Toxin Plasmids of Clostridium perfringens

    PubMed Central

    Li, Jihong; Adams, Vicki; Bannam, Trudi L.; Miyamoto, Kazuaki; Garcia, Jorge P.; Uzal, Francisco A.; Rood, Julian I.

    2013-01-01

    SUMMARY In both humans and animals, Clostridium perfringens is an important cause of histotoxic infections and diseases originating in the intestines, such as enteritis and enterotoxemia. The virulence of this Gram-positive, anaerobic bacterium is heavily dependent upon its prolific toxin-producing ability. Many of the ?16 toxins produced by C. perfringens are encoded by large plasmids that range in size from ?45 kb to ?140 kb. These plasmid-encoded toxins are often closely associated with mobile elements. A C. perfringens strain can carry up to three different toxin plasmids, with a single plasmid carrying up to three distinct toxin genes. Molecular Koch's postulate analyses have established the importance of several plasmid-encoded toxins when C. perfringens disease strains cause enteritis or enterotoxemias. Many toxin plasmids are closely related, suggesting a common evolutionary origin. In particular, most toxin plasmids and some antibiotic resistance plasmids of C. perfringens share an ?35-kb region containing a Tn916-related conjugation locus named tcp (transfer of clostridial plasmids). This tcp locus can mediate highly efficient conjugative transfer of these toxin or resistance plasmids. For example, conjugative transfer of a toxin plasmid from an infecting strain to C. perfringens normal intestinal flora strains may help to amplify and prolong an infection. Therefore, the presence of toxin genes on conjugative plasmids, particularly in association with insertion sequences that may mobilize these toxin genes, likely provides C. perfringens with considerable virulence plasticity and adaptability when it causes diseases originating in the gastrointestinal tract. PMID:23699255

  10. Marine neurotoxins: Ingestible toxins

    Microsoft Academic Search

    Elijah W. Stommel; Michael R. Watters

    2004-01-01

    Opinion statement  Fish and shellfish account for a significant portion of food-borne illnesses throughout the world. In general, three classes\\u000a of diseases result from seafood consumption—intoxication, allergies, and infections. In this review, the authors discuss several\\u000a seafood-borne toxins, including domoic acid, which acts on the central nervous system. In addition, the authors discuss ciguatoxin-,\\u000a brevetoxin-, saxitoxin-, tetrodotoxin-, and scombroid-related histamine toxicity,

  11. Toxins of cyanobacteria.

    PubMed

    van Apeldoorn, Marian E; van Egmond, Hans P; Speijers, Gerrit J A; Bakker, Guido J I

    2007-01-01

    Blue-green algae are found in lakes, ponds, rivers and brackish waters throughout the world. In case of excessive growth such as bloom formation, these bacteria can produce inherent toxins in quantities causing toxicity in mammals, including humans. These cyanotoxins include cyclic peptides and alkaloids. Among the cyclic peptides are the microcystins and the nodularins. The alkaloids include anatoxin-a, anatoxin-a(S), cylindrospermopsin, saxitoxins (STXs), aplysiatoxins and lyngbyatoxin. Both biological and chemical methods are used to determine cyanotoxins. Bioassays and biochemical assays are nonspecific, so they can only be used as screening methods. HPLC has some good prospects. For the subsequent detection of these toxins different detectors may be used, ranging from simple UV-spectrometry via fluorescence detection to various types of MS. The main problem in the determination of cyanobacterial toxins is the lack of reference materials of all relevant toxins. In general, toxicity data on cyanotoxins are rather scarce. A majority of toxicity data are known to be of microcystin-LR. For nodularins, data from a few animal studies are available. For the alkaloids, limited toxicity data exist for anatoxin-a, cylindrospermopsin and STX. Risk assessment for acute exposure could be relevant for some types of exposure. Nevertheless, no acute reference doses have formally been derived thus far. For STX(s), many countries have established tolerance levels in bivalves, but these limits were set in view of STX(s) as biotoxins, accumulating in marine shellfish. Official regulations for other cyanotoxins have not been established, although some (provisional) guideline values have been derived for microcystins in drinking water by WHO and several countries. PMID:17195276

  12. STI usefulness during isometric exercise in labile hypertensive patients.

    PubMed

    Cinelli, P; Romano, S; Calzolari, F; Israel, M; Gizdulich, P; Mori, F

    1982-01-01

    Measurement of the left ventricular systolic time intervals (STI) was considered a valid method in demonstrating the presence of a state of beta-drenergic hyperstimulation. The authors used this method during isometric exercise to differentiate between a group of 16 normal subjects (N) and 16 random labile hypertensives (LH), and between the N and 16 fixed hypertensives (FH). Exercise resulted in a general shortening (p less than 0.01) of the STI, an increase (p less than 0.01) in the systolic arterial pressure (SAP), and an increase (p less than 0.01) in the heart rate (HR) in all the groups studied. The study also demonstrated that the state of blood pressure (diagnosis) alone does not significantly influence the course of the exercise test, and that the interaction diagnosis-exercise gives quantitatively different results in the three groups, to the extent that it is possible to recognize a specific polygraphic pattern for the LH. In this group there is a greater shortening of the Q--S2 and the non-corrected LVET (p less than 0.01) than for the N. The behaviour for the FH falls between the other groups, but it is not possible to distinguish clearly between this group and its neighbour on either side. We conclude that the measurement of the STI during isometric exercise could be useful in determining a diagnostic pattern for subjects who show a lability in their blood pressure. PMID:6983803

  13. cAMP imaging of cells treated with pertussis toxin, cholera toxin, and anthrax edema toxin.

    PubMed

    Dal Molin, Federica; Zornetta, Irene; Puhar, Andrea; Tonello, Fiorella; Zaccolo, Manuela; Montecucco, Cesare

    2008-11-14

    The enzymatic activity of the three most studied bacterial toxins that increase the cytosolic cAMP level: pertussis toxin (PT), cholera toxin (CT), and anthrax edema toxin (ET), was imaged by fluorescence videomicroscopy. Three different cell lines were transfected with a fluorescence resonance energy transfer biosensor based on the PKA regulatory and catalytic subunits fused to CFP and YFP, respectively. Real-time imaging of cells expressing this cAMP biosensor provided time and space resolved pictures of the toxins action. The time course of the PT-induced cAMP increase suggests that its active subunit enters the cytosol more rapidly than that deduced by biochemical experiments. ET generated cAMP concentration gradients decreasing from the nucleus to the cell periphery. On the contrary, CT, which acts on the plasma membrane adenylate cyclase, did not. The potential of imaging methods in studying the mode of entry and the intracellular action of bacterial toxins is discussed. PMID:18793614

  14. Ratcheting up protein translocation with anthrax toxin

    PubMed Central

    Feld, Geoffrey K; Brown, Michael J; Krantz, Bryan A

    2012-01-01

    Energy-consuming nanomachines catalyze the directed movement of biopolymers in the cell. They are found both dissolved in the aqueous cytosol as well as embedded in lipid bilayers. Inquiries into the molecular mechanism of nanomachine-catalyzed biopolymer transport have revealed that these machines are equipped with molecular parts, including adjustable clamps, levers, and adaptors, which interact favorably with substrate polypeptides. Biological nanomachines that catalyze protein transport, known as translocases, often require that their substrate proteins unfold before translocation. An unstructured protein chain is likely entropically challenging to bind, push, or pull in a directional manner, especially in a way that produces an unfolding force. A number of ingenious solutions to this problem are now evident in the anthrax toxin system, a model used to study protein translocation. Here we highlight molecular ratchets and current research on anthrax toxin translocation. A picture is emerging of proton-gradient-driven anthrax toxin translocation, and its associated ratchet mechanism likely applies broadly to other systems. We suggest a cyclical thermodynamic order-to-disorder mechanism (akin to a heat-engine cycle) is central to underlying protein translocation: peptide substrates nonspecifically bind to molecular clamps, which possess adjustable affinities; polypeptide substrates compress into helical structures; these clamps undergo proton-gated switching; and the substrate subsequently expands regaining its unfolded state conformational entropy upon translocation. PMID:22374876

  15. Ratcheting up protein translocation with anthrax toxin.

    PubMed

    Feld, Geoffrey K; Brown, Michael J; Krantz, Bryan A

    2012-05-01

    Energy-consuming nanomachines catalyze the directed movement of biopolymers in the cell. They are found both dissolved in the aqueous cytosol as well as embedded in lipid bilayers. Inquiries into the molecular mechanism of nanomachine-catalyzed biopolymer transport have revealed that these machines are equipped with molecular parts, including adjustable clamps, levers, and adaptors, which interact favorably with substrate polypeptides. Biological nanomachines that catalyze protein transport, known as translocases, often require that their substrate proteins unfold before translocation. An unstructured protein chain is likely entropically challenging to bind, push, or pull in a directional manner, especially in a way that produces an unfolding force. A number of ingenious solutions to this problem are now evident in the anthrax toxin system, a model used to study protein translocation. Here we highlight molecular ratchets and current research on anthrax toxin translocation. A picture is emerging of proton-gradient-driven anthrax toxin translocation, and its associated ratchet mechanism likely applies broadly to other systems. We suggest a cyclical thermodynamic order-to-disorder mechanism (akin to a heat-engine cycle) is central to underlying protein translocation: peptide substrates nonspecifically bind to molecular clamps, which possess adjustable affinities; polypeptide substrates compress into helical structures; these clamps undergo proton-gated switching; and the substrate subsequently expands regaining its unfolded state conformational entropy upon translocation. PMID:22374876

  16. Diagnostic multiplex PCR for toxin genotyping of Clostridium perfringens isolates

    Microsoft Academic Search

    Christoph G Baums; Ulrich Schotte; Gunter Amtsberg; Ralph Goethe

    2004-01-01

    In this study we provide a protocol for genotyping Clostridium perfringens with a new multiplex PCR. This PCR enables reliable and specific detection of the toxin genes cpa, cpb, etx, iap, cpe and cpb2 from heat lysed bacterial suspensions. The efficiency of the protocol was demonstrated by typing C. perfringens reference strains and isolates from veterinary bacteriological routine diagnostic specimens.

  17. Diagnostic multiplex PCR for toxin genotyping of Clostridium perfringens isolates.

    PubMed

    Baums, Christoph G; Schotte, Ulrich; Amtsberg, Gunter; Goethe, Ralph

    2004-05-20

    In this study we provide a protocol for genotyping Clostridium perfringens with a new multiplex PCR. This PCR enables reliable and specific detection of the toxin genes cpa, cpb, etx, iap, cpe and cpb2 from heat lysed bacterial suspensions. The efficiency of the protocol was demonstrated by typing C. perfringens reference strains and isolates from veterinary bacteriological routine diagnostic specimens. PMID:15135508

  18. Harnessing Labile Bonds between Nanogels Particles to Create Self-Healing Materials

    Microsoft Academic Search

    German V. Kolmakov; Krzysztof Matyjaszewski; Anna C. Balazs

    2009-01-01

    Using computational modeling, we demonstrate the self-healing behavior of novel materials composed of nanoscopic gel particles that are interconnected into a macroscopic network by both stable and labile bonds. Under mechanical stress, the labile bonds between the nanogels can break and readily reform with reactive groups on neighboring units. This breaking and reforming allows the units in the network to

  19. Labile carbon and nitrogen from rhizoplane and surface soils of two perennial grasslands

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In semiarid perennial grasslands biogeochemical processes that drive nutrient dynamics may be more closely related to the quantity of labile SOM than to total SOM. A small ephemeral pool of labile soluble organic matter becomes active after pulse precipitation events. Rhizoplane soil associated with...

  20. Whole-ecosystem labile carbon production in a north temperate deciduous forest

    Microsoft Academic Search

    Christopher M. Gough; Charles E. Flower; Christoph S. Vogel; Danilo Dragoni; Peter S. Curtis

    2009-01-01

    Labile carbon (C), which is principally comprised of non-structural carbohydrates, is an essential intermediary between C assimilation and structural growth in deciduous forests. We developed a new approach that combined meteorological and biometric C cycling data for a mixed deciduous forest in Michigan, USA, to provide novel estimates of whole-ecosystem labile C production and reallocation to structural net primary production

  1. Toxins from the box-jellyfish Chironex fleckeri.

    PubMed

    Endean, R; Monks, S A; Cameron, A M

    1993-04-01

    Two myotoxins (T1 and T2) with mol. wts of approximately 600,000 and 150,000, respectively, and a haemolysin (T3) with a mol. wt of approximately 70,000 were isolated from the crude nematocyst venom of C. fleckeri by the use of Sephadex G-200 chromatography. A neurotoxic fraction (T4) and a haemolytic fraction (T5) containing proteins with apparent mol. wts of approximately 150,000 and 70,000, respectively, were also isolated by Sephadex chromatography from crude extracts of tentacular material from which nematocysts had been removed. The three nematocyst toxins and the two toxic fractions from tentacle extracts were lethal to mice on i.v. injection. After SDS-PAGE the myotoxins T1 and T2 yielded similar major bands corresponding with mol. wts different from those yielded by T3 and the toxic tentacle fractions. T1 and T2 appeared to be comprised of aggregations of subunits with mol. wts of approximately 18,000. On HPLC, crude nematocyst venom and the nematocyst toxins T1 and T2 lost their myotoxic properties. The need for thorough removal of extraneous tentacular material from isolated nematocysts, the need for effective rupture of nematocysts, the need to counter the lability of the nematocyst venom and the need to use myotoxicity as a criterion of venom activity if the active components of the venom are to be purified and characterized are emphasized. PMID:8099238

  2. Lymphocyte receptors for pertussis toxin.

    PubMed Central

    Clark, C G; Armstrong, G D

    1990-01-01

    We have investigated human T-lymphocyte receptors for pertussis toxin by affinity isolation and photoaffinity labeling procedures. T lymphocytes were obtained from peripheral human blood, surface iodinated, and solubilized in Triton X-100. The iodinated mixture was then passed through pertussis toxin-agarose, and the fractions were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Autoradiography of the fixed, dried gels revealed several bands in the pertussis toxin-bound fraction that were not observed in fractions obtained from histone or fetuin-agarose. Further investigations employed a photoaffinity labeling reagent, sulfosuccinimidyl 2-(p-azido-salicylamido)-1,3'-dithiopropionate, to identify pertussis toxin receptors in freshly isolated peripheral blood monocytic cells, T lymphocytes, and Jurkat cells. In all three cell systems, the pertussis toxin affinity probe specifically labeled a single protein species with an apparent molecular weight of 70,000 that was not observed when the procedure was performed in the presence of excess unmodified pertussis toxin. A protein comparable in molecular weight to the one detected by the photoaffinity labeling technique was also observed among the species that bound to pertussis toxin-agarose. The results suggest that pertussis toxin may bind to a 70,000-Da receptor in human T lymphocytes. Images PMID:2123822

  3. Lectinlike properties of pertussis toxin.

    PubMed Central

    Tyrrell, G. J.; Peppler, M. S.; Bonnah, R. A.; Clark, C. G.; Chong, P.; Armstrong, G. D.

    1989-01-01

    We have examined the lectinlike properties of pertussis toxin by binding-inhibition assays and affinity chromatography of goose erythrocyte membranes. Although pertussis toxin and wheat germ agglutinin apparently recognize similar sugar sequences on glycoproteins, the binding activities of the two lectins are not identical. Images PMID:2722243

  4. Novel Structure and Function of Typhoid Toxin

    MedlinePLUS

    ... toxin, it caused symptoms similar to those in humans with typhoid fever, implicating typhoid toxin in the illness caused by S. typhi. Typhoid toxin can bind to a wide variety of cells. Experiments revealed that the toxin attaches to certain types ...

  5. Food toxin detection with atomic force microscope

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Externally introduced toxins or internal spoilage correlated pathogens and their metabolites are all potential sources of food toxins. To prevent and protect unsafe food, many food toxin detection techniques have been developed to detect various toxins for quality control. Although several routine m...

  6. Effectiveness of botulinum toxin A in treatment of refractory erythromelalgia.

    PubMed

    Lin, Kuan-Hsiang; Wang, Shuu-Jiun; Fuh, Jong-Ling; Chen, Shih-Pin

    2013-05-01

    Erythromelalgia is characterized by intense burning pain, erythema, and heat in affected areas after precipitating factors such as warm temperature or stress. It is refractory to treatment in some situations. We describe a woman with adenosquamous cell carcinoma of the lung and medically refractory erythromelalgia. The symptoms of erythromelalgia presented as refractory to any medical treatment. Due to the unresponsive nature of her condition, botulinum toxin type A (onabotulinumtoxin A) was injected over both of her cheeks, periodically for six cycles. Her symptoms responded dramatically to subcutaneous and intradermal injection of botulinum toxin type A. Repetitive injection demonstrated consistent and reproducible responses, and the efficacy was maintained for approximately 1 month. No adverse effects or complications were noted. Botulinum toxin type A might be safe and effective as an alternative treatment for refractory erythromelalgia, but further large-scale studies are required. PMID:23683264

  7. The three-dimensional crystal structure of cholera toxin

    SciTech Connect

    Zhang, Rong-Guang; Westbrook, M.L.; Nance, S.; Spangler, B.D. [Argonne National Lab., IL (United States); Scott, D.L. [Yale Univ., New Haven, CT (United States). Dept. of Molecular Biophysics and Biochemistry; Westbrook, E.M. [Northwestern Univ., Evanston, IL (United States)

    1996-02-01

    The clinical manifestations of cholera are largely attributable to the actions of a secreted hexameric AB{sub 5} enterotoxin (choleragen). We have solved the three-dimensional structure of choleragen at 2.5 {Angstrom} resolution and compared the refined coordinates with those of choleragenoid (isolated B pentamer) and the heat-labile enterotoxin from Escherichia coli (LT). The crystalline coordinates provide a detailed view of the stereochemistry implicated in binding to GM1 gangliosides and in carrying out ADP-ribosylation. The A2 chain of choleragen, in contrast to that of LT, is a nearly continuous {alpha}-helix with an interpretable carboxyl tail.

  8. Anthrax Toxin Receptor 2–Dependent Lethal Toxin Killing In Vivo

    Microsoft Academic Search

    Heather M. Scobie; Darran J. Wigelsworth; John M. Marlett; Diane Thomas; G. Jonah A. Rainey; D. Borden Lacy; Marianne Manchester; R. John Collier; John A. T. Young

    2006-01-01

    Anthrax toxin receptors 1 and 2 (ANTXR1 and ANTXR2) have a related integrin-like inserted (I) domain which interacts with a metal cation that is coordinated by residue D683 of the protective antigen (PA) subunit of anthrax toxin. The receptor-bound metal ion and PA residue D683 are critical for ANTXR1-PA binding. Since PA can bind to ANTXR2 with reduced affinity in

  9. A Bivalent Tarantula Toxin Activates the Capsaicin Receptor, TRPV1, by Targeting the Outer Pore Domain

    PubMed Central

    Bohlen, Christopher J.; Priel, Avi; Zhou, Sharleen; King, David; Siemens, Jan; Julius, David

    2010-01-01

    SUMMARY Toxins have evolved to target regions of membrane ion channels that underlie ligand binding, gating, or ion permeation, and have thus served as invaluable tools for probing channel structure and function. Here we describe a peptide toxin from the Earth Tiger tarantula that selectively and irreversibly activates the capsaicin- and heat-sensitive channel, TRPV1. This high avidity interaction derives from a unique tandem repeat structure of the toxin that endows it with an antibody-like bivalency, illustrating a new paradigm in toxin structure and evolution. The ‘double-knot’ toxin traps TRPV1 in the open state by interacting with residues in the presumptive pore-forming region of the channel, highlighting the importance of conformational changes in the outer pore region of TRP channels during activation. PMID:20510930

  10. Capturing labile sulfenamide and sulfinamide serum albumin adducts of carcinogenic arylamines by chemical oxidation.

    PubMed

    Peng, Lijuan; Turesky, Robert J

    2013-01-15

    Aromatic amines and heterocyclic aromatic amines (HAAs) are a class of structurally related carcinogens that are formed during the combustion of tobacco or during the high temperature cooking of meats. These procarcinogens undergo metabolic activation by N-oxidation of the exocyclic amine group to produce N-hydroxylated metabolites, which are critical intermediates implicated in toxicity and DNA damage. The arylhydroxylamines and their oxidized arylnitroso derivatives can also react with cysteine (Cys) residues of glutathione or proteins to form, respectively, sulfenamide and sulfinamide adducts. However, sulfur-nitrogen linked adducted proteins are often difficult to detect because they are unstable and undergo hydrolysis during proteolytic digestion. Synthetic N-oxidized intermediates of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), a carcinogenic HAA produced in cooked meats, and 4-aminobiphenyl, a carcinogenic aromatic amine present in tobacco smoke, were reacted with human serum albumin (SA) and formed labile sulfenamide or sulfinamide adducts at the Cys(34) residue. Oxidation of the carcinogen-modified SA with m-chloroperoxybenzoic acid (m-CPBA) produced the arylsulfonamide adducts, which were stable to heat and the chemical reduction conditions employed to denature SA. The sulfonamide adducts of PhIP and 4-ABP were identified, by liquid chromatography/mass spectrometry, in proteolytic digests of denatured SA. Thus, selective oxidation of arylamine-modified SA produces stable arylsulfonamide-SA adducts, which may serve as biomarkers of these tobacco and dietary carcinogens. PMID:23240913

  11. Isolation of B subunit-specific monoclonal antibody clones that strongly neutralize the toxicity of Shiga toxin 2.

    PubMed

    Arimitsu, Hideyuki; Sasaki, Keiko; Iba, Yoshitaka; Kurosawa, Yoshikazu; Shimizu, Toshiyasu; Tsuji, Takao

    2015-02-01

    Shiga toxin 2 (Stx2)-specific mAb-producing hybridoma clones were generated from mice. Because mice tend to produce small amounts of B subunit (Stx2B)-specific antibodies at the polyclonal antibody level after immunization via the parenteral route, mice were immunized intranasally with Stx2 toxoids with a mutant heat-labile enterotoxin as a mucosal adjuvant; 11 different hybridoma clones were obtained in two trials. Six of them were A subunit (Stx2A)-specific whereas five were Stx2B-specific antibody-producing clones. The in vitro neutralization activity of Stx2B-specific mAbs against Stx2 was greater than that of Stx2A-specific mAbs on HeLa229 cells. Furthermore, even at low concentrations two of the Stx2B-specific mAbs (45 and 75D9) completely inhibited receptor binding and showed in vivo neutralization activity against a fivefold median lethal dose of Stx2 in mice. In western blot analysis, these Stx2B-specific neutralization antibodies did not react to three different mutant forms of Stx2, each amino acid residue of which was associated with receptor binding. Additionally, the nucleotide sequences of the VH and VL regions of clones 45 and 75D9 were determined. Our Stx2B-specific mAbs may be new candidates for the development of mouse-human chimeric Stx2-neutralizing antibodies which have fewer adverse effects than animal antibodies for enterohemorrhagic Escherichia coli infection. PMID:25521016

  12. Probing interactions within anthrax toxin by electron paramagnetic resonance

    E-print Network

    Probing interactions within anthrax toxin by electron paramagnetic resonance Laura D. Jennings of anthrax toxin forms oligomeric pores that translocate the enzymatic moieties of the toxin -- lethal factor

  13. Cholera Toxin Mechanism of Action

    NSDL National Science Digital Library

    American Society For Microbiology

    2002-08-29

    This single image file shows the steps of action of cholera toxin, beginning at protein synthesis in the bacteria and proceeding through all of the major known steps of interaction with the host cell.

  14. Anticariogenic and phytochemical evaluation of Eucalyptus globules Labill.

    PubMed Central

    Ishnava, Kalpesh B.; Chauhan, Jenabhai B.; Barad, Mahesh B.

    2012-01-01

    In the present study, in vitro anticariogenic potential of ethyl acetate, hexane and methanol and aqueous extracts of plant leaves of Eucalyptus globules Labill. were evaluated by using four cariogenic bacteria, Lactobacillus acidophilus, Lactobacillus casei, Staphylococcus aureus and Streptococcus mutans. Agar well diffusion method and minimum inhibitory concentration (MIC) were used for this purpose. The ethyl acetate extracted fraction of plant leaves showed good inhibitory effects against all selected bacteria. In Eucalyptus globules, hexane and ethyl acetate extracts found highly effective against, Lactobacillus acidophilus with MIC value of 0.031 and 0.062 mg/mL, respectively. Qualitative phytochemical investigation of above extracts showed the presence of alkaloids, phenolic compounds, steroids, cardiac glycosides and terpenes. Based on the MIC value and bioautography, ethyl acetate of plant leaf was selected for further study. Further investigation on the structure elucidation of the bioactive compound using IR, GC-MS and NMR techniques revealed the presence of alpha-farnesene, a sesquiterpene. Eucalyptus globules plant leaf extracts have great potential as anticariogenic agents that may be useful in the treatment of oral disease. PMID:23961222

  15. Cold lability of pyruvate, orthophosphate dikinase in the maize leaf.

    PubMed

    Shirahashi, K; Hayakawa, S; Sugiyama, T

    1978-11-01

    Cold lability of pyruvate, orthophosphate dikinase was investigated using a homogeneous, purified enzyme preparation from maize (Zea mays L. var. Golden Cross Bantam T51) leaves. Its stability was markedly reduced below about 10 C and the rate of cold inactivation followed first order kinetics at a concentration lower than about 0.1 milligram of enzyme per milliliter. Cold inactivation was little affected by pH in the range which gives good stability for the enzyme at warm temperatures and the enzyme activity was protected strongly by inclusion of substrates (pyruvate and phosphoenolpyruvate) and polyols such as sucrose, sorbitol, and glycerol. Loss of catalytic activity was accompanied by an apparent dissociation of a tetrameric form of the enzyme (9S form) into a new, more slowly sedimenting (5.1S) component. Inclusion of pyruvate at 4 mM in the cold-treated enzyme had no effect on the sedimentation value. A sharp change in activation energy of the dikinase-catalyzed reaction was observed near 12 C and its break point appears to be close to the generally accepted critical low temperature limit for the growth of maize plants. PMID:16660615

  16. Stereochemical lability of azatitanacyclopropanes: dynamic kinetic resolution in reductive cross-coupling reactions with allylic alcohols.

    PubMed

    Yang, Dexi; Micalizio, Glenn C

    2013-10-01

    Azatitanacyclopropanes (titanaziridines) are shown to be stereochemically labile under reaction conditions for reductive cross-coupling. This fundamental property has been employed to realize highly selective asymmetric coupling reactions with allylic alcohols that proceed by dynamic kinetic resolution. PMID:23963189

  17. Biogeochemical implications of labile phosphorus in forest soils determined by the Hedley fractionation procedure

    Microsoft Academic Search

    Arthur H. Johnson; Jaqueline Frizano; David R. Vann

    2003-01-01

    Forest ecologists and biogeochemists have used a variety of extraction techniques to assess labile vs. non-labile soil P pools in chronosequences, the balance between biological vs. geochemical control of P transformations across a wide range of soil orders, the role of plants with either N-fixing or mycorrhizal symbionts in controlling soil P fractions, and to make inferences about plant-available P.

  18. Ethylenediaminetetraacetic acid (disodium salt)-labile bovine immunoglobulin M Fc binding to Brucella abortus: a cause of nonspecific agglutination.

    PubMed Central

    Nielsen, K; Stilwell, K; Stemshorn, B; Duncan, R

    1981-01-01

    It was demonstrated by a radioimmunoassay procedure that Brucella abortus agglutinins from noninfected cattle sera, absorbed to B. abortus antigen and eluted with ethylenediaminetetraacetic acid (EDTA), was immunoglobulin M that bound to that bacterium by its Fc portion. The EDTA-eluted immunoglobulin M agglutinated intact B. abortus cells but not erythrocytes treated with B. abortus lipopolysaccharide. The specificity of the EDTA-eluted immunoglobulin was for B. abortus, although a small titer to Yersinia enterocolitica serotype O:9 was observed. In contrast, immunoglobulin M purified from the serum of a cow injected 7 days previously with heat-killed B. abortus bound to the antigen by its Fab portion, was not labile to EDTA treatment, cross-reacted extensively with Y. enterocolitica serotype O:9, and agglutinated various other bacterial antigens and normal erythrocytes. Images PMID:6790568

  19. Selective trapping of labile S3 in a porous coordination network and the direct X-ray observation.

    PubMed

    Ohtsu, Hiroyoshi; Choi, Wanuk; Islam, Nazrul; Matsushita, Yoshitaka; Kawano, Masaki

    2013-08-01

    S3 is one of the basic allotropes of sulfur but is still a mysterious labile species. We selectively trapped S3 in a pore of a thermally stable coordination network and determined S3 structure by ab initio X-ray powder diffraction analysis. S3 in a pore has a C2v bent structure. The network containing trapped S3 is remarkably stable under ambient conditions and is inert to photoirradiation. S3 in the network could be transformed to S6 by mechanical grinding or heating in the presence of NH4X (X = Cl or Br). S6 could be reverse-transformed to S3 by photoirradiation. We also determined the structure of the network containing S6 by ab initio X-ray powder diffraction analysis. PMID:23879312

  20. Concentration-dependent absorption of aluminum in rats exposed to labile aluminum in drinking water.

    PubMed

    Glynn, A W; Sparén, A; Danielsson, L G; Sundström, B; Jorhem, L

    1999-04-01

    The hypothesis was tested that the absorption of labile Al in rats will increase when the Al-binding capacity of food components in the stomach is saturated. Male rats were exposed to 0, 10, 50, or 500 mg labile Al/L in acidic drinking water (pH 3) for 9 wk. The results show that labile Al in drinking water is complexed by feed constituents in the stomach of the rat in vivo, thus causing a nondetectable absorption of Al at 10 mg Al/L. An increased absorption of Al at 50 and 500 mg Al/L was associated with a saturation of the Al-binding capacity of feed components in the lumen of the stomach, causing the appearance of labile Al. Thus, the presence of labile Al in drinking water does not necessarily result in a high Al absorption when the water is ingested, since the bioavailability of labile Al is dependent both on the amount and composition of Al-binding components present in the gastrointestinal tract at the time of ingestion of the water. It is thus not possible to predict the body burden of Al in humans just by measuring the Al concentrations in drinking water. Even a further refining of the exposure measurement to include speciation of Al in the water may not markedly improve the prediction of the Al body burden. Future epidemiological studies must therefore be based on actual measurements of Al concentration in tissues or fluids from the study subjects. PMID:10201636

  1. Thermally labile components of aqueous humor potently induce osteogenic potential in adipose-derived mesenchymal stem cells.

    PubMed

    Morgan, Joshua T; Kwon, Heung Sun; Wood, Joshua A; Borjesson, Dori L; Tomarev, Stanislav I; Murphy, Christopher J; Russell, Paul

    2015-06-01

    Adipose-derived mesenchymal stem cells (ASCs) hold promise for use in cell-based therapies. Their intrinsic anti-inflammatory properties are potentially useful for treatments of inflammatory conditions such as uveitis, while their ability to differentiate along multiple cell lineages suggests use in regenerating damaged or degenerated tissue. However, how ASCs will respond to the intraocular environment is poorly studied. We have recently reported that aqueous humor (AH), the fluid that nourishes the anterior segment of the eye, potently increases alkaline phosphatase (ALP) activity of ASCs, indicating osteogenic differentiation. Here, we expand on our previous findings to better define the nature of this response. To this end, we cultured ASCs in the presence of 0, 5, 10, and 20% AH and assayed them for ALP activity. We found ALP activity correlates with increasing AH concentrations from 5 to 20%, and that longer treatments result in increased ALP activity. By using serum free media and pretreating AH with dextran-coated charcoal, we found that serum and charcoal-adsorbable AH components augment but are not required for this response. Further, by heat-treating the AH, we established that thermally labile components are required for the osteogenic response. Finally, we showed myocilin, a protein present in AH, could induce ALP activity in ASCs. However, this was to a lesser extent than untreated 5% AH, and myocilin could only partially rescue the effect after heat treatment, documenting there were additional thermally labile constituents of AH involved in the osteogenic response. Our work adds to the understanding of the induction of ALP in ASCs following exposure to AH, providing important insight in how ASCs will be influenced by the ocular environment. In conclusion, increased osteogenic potential upon exposure to AH represents a potential challenge to developing ASC cell-based therapies directed at the eye. PMID:25720657

  2. Neuropsychological correlates of emotional lability in children with ADHD

    PubMed Central

    Banaschewski, Tobias; Jennen-Steinmetz, Christine; Brandeis, Daniel; Buitelaar, Jan K.; Kuntsi, Jonna; Poustka, Luise; Sergeant, Joseph A.; Sonuga-Barke, Edmund J.; Frazier-Wood, Alexis C.; Albrecht, Björn; Chen, Wai; Uebel, Henrik; Schlotz, Wolff; van der Meere, Jaap J.; Gill, Michael; Manor, Iris; Miranda, Ana; Mulas, Fernando; Oades, Robert D.; Roeyers, Herbert; Rothenberger, Aribert; Steinhausen, Hans-Christoph; Faraone, Stephen V.; Asherson, Philip

    2012-01-01

    Background Emotional lability (EL) is commonly seen in patients with Attention Deficit/Hyperactivity Disorder (ADHD). The reasons for this association are currently unknown. To address this question we examined the relationship between ADHD and EL symptoms, and performance on a range of neuropsychological tasks to clarify whether EL symptoms are predicted by particular cognitive and/or motivational dysfunctions and whether these associations are mediated by the presence of ADHD symptoms. Methods A large multi-site sample of 424 carefully diagnosed ADHD cases and 564 unaffected siblings and controls aged 6 to 18 years performed a broad neuropsychological test battery, including a Go/No-Go Task, a warned 4-choice Reaction Time task, the Maudsley Index of Childhood Delay Aversion, and Digit span backwards. Neuropsychological variables were aggregated as indices of processing speed, response variability, executive functions, choice impulsivity and the influence of energetic and/or motivational factors. EL and ADHD symptoms were regressed on each neuropsychological variable in separate analyses controlling for age, gender and IQ, and, in subsequent regression analyses, for ADHD and EL symptoms respectively. Results Neuropsychological variables significantly predicted ADHD and EL symptoms with moderate to low regression coefficients. However, the association between neuropsychological parameters on EL disappeared entirely when the effect of ADHD symptoms was taken into account, revealing that the association between the neuropsychological performance measures and EL is completely mediated statistically by variations in ADHD symptoms. Conversely, neuropsychological effects on ADHD symptoms remained after EL symptom severity was taken into account. Conclusions The neuropsychological parameters examined here predict ADHD more strongly than EL. They cannot explain EL symptoms beyond what is already accounted for by ADHD symptom severity. The association between EL and ADHD cannot be explained by these cognitive or motivational deficits. Alternative mechanisms, including overlapping genetic influences (pleiotropic effects), and/or alternative neuropsychological processes need to be considered. PMID:22882111

  3. Cholera toxin, and the related nontoxic adjuvants mmCT and dmLT, promote human Th17 responses via cyclic AMP-protein kinase A and inflammasome-dependent IL-1 signaling.

    PubMed

    Larena, Maximilian; Holmgren, Jan; Lebens, Michael; Terrinoni, Manuela; Lundgren, Anna

    2015-04-15

    We have examined the molecular pathways involved in the adjuvant action of cholera toxin (CT) and two novel nontoxic molecules, multiple-mutated CT (mmCT) and double-mutant heat-labile toxin (dmLT) on human T cell responses. Human PBMCs or isolated monocytes were stimulated in vitro with CT, mmCT, or dmLT plus a polyclonal stimulus (staphylococcal enterotoxin B) or specific bacterial Ags, and effects on expression of cytokines and signaling molecules were determined. CT, mmCT, and dmLT strongly enhanced IL-17A and to a lesser extent IL-13 responses, but had little effect on IFN-? production or cell proliferation. Intracellular cytokine staining revealed that the enhanced IL-17A production was largely confined to CD4(+) T cells and coculture experiments showed that the IL-17A promotion was effectively induced by adjuvant-treated monocytes. Relative to CT, mmCT and dmLT induced at least 100-fold lower levels of cAMP, yet this cAMP was enough and essential for the promotion of Th17 responses. Thus, inhibition of cAMP-dependent protein kinase A was abolished, and stimulation with a cAMP analog mimicked the adjuvant effect. Furthermore, CT, mmCT, and dmLT induced IL-1? production and caspase-1 activation in monocytes, which was associated with increased expression of key proinflammatory and inflammasome-related genes, including NLRP1, NLRP3, and NLRC4. Inflammasome inhibition with a specific caspase-1 inhibitor, or blocking of IL-1 signaling by IL-1 receptor antagonist, abrogated the Th17-promoting effect. We conclude that CT, mmCT, and dmLT promote human Th17 responses via cAMP-dependent protein kinase A and caspase-1/inflammasome-dependent IL-1 signaling. PMID:25786687

  4. Redistribution of Labile Plasma Zinc During Mild Surgical Stress in the Rat

    PubMed Central

    Kelly, Edward; Mathew, Jeffrey; Kohler, Jonathan E.; Blass, Amy L.; Soybel, David I.

    2011-01-01

    Zinc is an essential trace element and co-factor for many cellular processes. Uptake of Zn2+ in peripheral tissues depends on its total content in the circulation, and on mechanisms facilitating delivery to tissues in its labile form. Understanding mechanisms of Zn2+ delivery has been hindered by the absence of techniques to detect labile Zn2+ in the circulation. In this study, we report the use of the fluorescent zinc-binding dye, ZnAF-2, to detect changes in labile Zn2+ in the circulating plasma of the rat under standardized conditions, including exogenous infusions to raise plasma Zn2+, and infusion of the chelator, citrate, to lower labile Zn2+ in the plasma without altering total Zn2+ content. In a model of mild surgical stress (unilateral femoral arterial ligation), plasma levels of total and labile Zn2+ decreased significantly 24 hours following operation. Ultrafiltration of plasma into high and low molecular weight macromolecule fractionations indicated that binding capacity of zinc in the high molecular weight fraction is impaired for the entire 24 hour interval following induction of mild surgical stress. Affinity of the filtrate fraction was rapidly and reversibly responsive to anesthesia alone, decreasing significantly at 4 hours and recovering at 24 hours; in animals subjected to moderate surgical stress this responsiveness was lost. These are the first reported measurements of labile Zn2+ in the circulation in any form of mild systemic stress. Zinc undergoes substantial redistribution in the plasma, response to surgical stress, leading to increased availability in lower molecular weight fractions and in its labile form. PMID:21316030

  5. Natural Toxins: The Past and the Present

    Microsoft Academic Search

    E. Grishin

    Different bacteria, viruses and toxins constitute a potential menace for people. The number of toxins that could be applied\\u000a for a bioterrorist attack with real public health risk, though, is relatively limited. However, these natural toxins could\\u000a cause difficult troubles. The objective of this paper is focused on the toxins of various origins that might be used as a\\u000a biological

  6. Receptors of anthrax toxin and cell entry.

    PubMed

    van der Goot, Gisou; Young, John A T

    2009-12-01

    Anthrax toxin-receptor interactions are critical for toxin delivery to the host cell cytoplasm. This review summarizes what is known about the molecular details of the protective antigen (PA) toxin subunit interaction with either the ANTXR1 and ANTXR2 cellular receptors, and how receptor-type can dictate the low pH threshold of PA pore formation. The roles played by cellular factors in regulating the endocytosis of toxin-receptor complexes is also discussed. PMID:19732789

  7. Purification of tritium-labeled cholera toxin.

    PubMed Central

    Banwell, J G; Hanke, D W; Diedrich, D

    1978-01-01

    Cholera toxin was labeled with tritium by the Wilzbach technique, and highly purified radiolabeled toxin was obtained by Sephadex column chromatography and disc gel electrophoresis. 3H-labeled cholera toxin retained its biological activity and chemical stability and had a specific activity of 405.9 muCi/mumol. The methods utilized in extraction and purification of 3H-labeled toxin may be advantageous for preparation of other biologically active radiolabeled proteins. Images PMID:689738

  8. Staphylococcal toxins and sudden infant death syndrome

    Microsoft Academic Search

    J E Malam; G F Carrick; D R Telford; J A Morris

    1992-01-01

    AIMS: To investigate the hypothesis that commonly occurring bacterial toxins cause sudden infant death syndrome (SIDS) by (1), determining in which tissues bacterial toxins are concentrated after intravenous injection in rats; and (2), seeing if the same tissues contain detectable toxins in cases of SIDS. METHODS: The tissue distribution of intravenously injected staphylococcal enterotoxin A (SEA), enterotoxin B (SEB), enterotoxin

  9. Differential priming of soil carbon driven by soil depth and root impacts on carbon lability

    NASA Astrophysics Data System (ADS)

    De Graaff, M.; Jastrow, J. D.; Gilette, S.; Johns, A.; Wullschleger, S. D.

    2012-12-01

    An increase in root-derived labile soil carbon (C) inputs (e.g. exudates) can stimulate decomposition of more recalcitrant soil organic carbon (SOC) by priming microbial activity, which can lead to a net loss of soil C storage. This priming effect can be small or large and negative or positive, but the mechanisms by which root-C controls the magnitude and direction of SOC decomposition remain poorly understood. With this study we evaluated how small versus large differences in labile soil C availability affect microbial processing of simulated root exudate inputs and decomposition of SOC. We conducted a laboratory incubation experiment (60 days) with soils collected from under six switchgrass (Panicum virgatum) cultivars to a depth of 60 cm. Differences in specific root length among cultivars were expected to result in small differences in labile soil C availability, whereas differences associated with soil depth were expected to result in large differences in labile soil C availability. Soil cores were divided into 0-10 cm, 20-30 cm and 40-60 cm depth increments, and soils of all cultivars (no roots) across all three depths were incubated with addition of either: (1) water (60% water holding capacity), or (2) labile C provided as a 13C-labeled synthetic root exudate cocktail. We measured CO2 respiration throughout the experiment. The switchgrass was grown for three years in soils that formerly supported C3 pasture grasses, and the natural difference in 13C signature between C3 and C4 plants enabled quantification of differences in the lability of root-derived C among cultivars. Moreover the 13C labeled synthetic root-exudate cocktail amendment to soils allowed us to assess impacts of exudates-C addition on priming in soil derived from the different cultivars and from different depths. Our experiment led to three main results: (1) different cultivars of switchgrass regulate labile C availability across the soil profile differently; (2) small differences in labile C among the soils derived from different cultivars did not significantly mediate the impact of exudates-C additions on priming; (3) but, large differences in labile soil C contents among depths led to differences in priming effects, where greater priming effects were observed for shallow relative to deep soils across all days of the experiment. These results suggest that increased root-derived C inputs will have marginal impacts on decomposition of more stable SOC at depth and that their impact on priming will be similar in soils with small differences in available soil C.

  10. Hard Exercise, Affect Lability, and Personality Among Individuals with Bulimia Nervosa

    PubMed Central

    Brownstone, Lisa M.; Fitzsimmons-Craft, Ellen E.; Wonderlich, Stephen A.; Joiner, Thomas E.; Le Grange, Daniel; Mitchell, James E.; Crow, Scott J.; Peterson, Carol B.; Crosby, Ross D.; Klein, Marjorie H.; Bardone-Cone, Anna M.

    2013-01-01

    The current study explores the personality traits of compulsivity (e.g., sense of orderliness and duty to perform tasks completely) and restricted expression (e.g., emotion expression difficulties) as potential moderators of the relation between affect lability and frequency of hard exercise episodes in a sample of individuals with bulimic pathology. Participants were 204 adult females recruited in five Midwestern cities who met criteria for threshold or subthreshold bulimia nervosa (BN). Compulsivity was found to significantly moderate the relation between affect lability and number of hard exercise episodes over the past 28 days, such that among those with high compulsivity, level of affect lability was associated with the number of hard exercise episodes; whereas, among those with low compulsivity, affect lability was not associated with the number of hard exercise episodes. The same pattern of findings emerged for restricted expression; however, this finding approached, but did not reach statistical significance. As such, it appears that affect lability is differentially related to hard exercise among individuals with BN depending upon the level of compulsivity and, to a more limited extent, restricted expression. These results suggest that, for individuals with BN with either compulsivity or restricted expression, focusing treatment on increasing flexibility and/or verbal expression of emotions may help them in the context of intense, fluctuating affect. PMID:24183126

  11. Recombinant Toxins for Cancer Treatment

    Microsoft Academic Search

    Ira Pastan; David Fitzgerald

    1991-01-01

    Recombinant toxins target cell surface receptors and antigens on tumor cells. They kill by mechanisms different from conventional chemotherapy, so that cross resistance to conventional chemotherapeutic agents should not be a problem. Furthermore, they are not mutagens and should not induce secondary malignancies or accelerate progression of benign malignancies. They can be mass-produced cheaply in bacteria as homogeneous proteins. Either

  12. The polychaete worm Nereis diversicolor increases mercury lability and methylation in intertidal mudflats.

    PubMed

    Sizmur, Tom; Canário, João; Edmonds, Samuel; Godfrey, Adam; O'Driscoll, Nelson J

    2013-08-01

    The polychaete worm Nereis diversicolor engineers its environment by creating oxygenated burrows in anoxic intertidal sediments. The authors carried out a laboratory microcosm experiment to test the impact of polychaete burrowing and feeding activity on the lability and methylation of mercury in sediments from the Bay of Fundy, Canada. The concentration of labile inorganic mercury and methylmercury in burrow walls was elevated compared to worm-free sediments. Mucus secretions and organic detritus in worm burrows increased labile mercury concentrations. Worms decreased sulfide concentrations, which increased Hg bioavailability to sulfate-reducing bacteria and increased methylmercury concentrations in burrow linings. Because the walls of polychaete burrows have a greater interaction with organisms, and the overlying water, the concentrations of mercury and methylmercury they contain is more toxicologically relevant to the base of a coastal food web than bulk samples. The authors recommend that researchers examining Hg in marine environments account for sediment dwelling invertebrate activity to more fully assess mercury bioavailability. PMID:23633443

  13. Inactivation of allergens and toxins.

    PubMed

    Morandini, Piero

    2010-11-30

    Plants are replete with thousands of proteins and small molecules, many of which are species-specific, poisonous or dangerous. Over time humans have learned to avoid dangerous plants or inactivate many toxic components in food plants, but there is still room for ameliorating food crops (and plants in general) in terms of their allergens and toxins content, especially in their edible parts. Inactivation at the genetic rather than physical or chemical level has many advantages and classical genetic approaches have resulted in significant reduction of toxin content. The capacity, offered by genetic engineering, of turning off (inactivating) specific genes has opened up the possibility of altering the plant content in a far more precise manner than previously available. Different levels of intervention (genes coding for toxins/allergens or for enzymes, transporters or regulators involved in their metabolism) are possible and there are several tools for inactivating genes, both direct (using chemical and physical mutagens, insertion of transposons and other genetic elements) and indirect (antisense RNA, RNA interference, microRNA, eventually leading to gene silencing). Each level/strategy has specific advantages and disadvantages (speed, costs, selectivity, stability, reversibility, frequency of desired genotype and regulatory regime). Paradigmatic examples from classical and transgenic approaches are discussed to emphasize the need to revise the present regulatory process. Reducing the content of natural toxins is a trade-off process: the lesser the content of natural toxins, the higher the susceptibility of a plant to pests and therefore the stronger the need to protect plants. As a consequence, more specific pesticides like Bt are needed to substitute for general pesticides. PMID:20601271

  14. Labile iron in cells and body fluids: physiology, pathology, and pharmacology

    PubMed Central

    Cabantchik, Zvi Ioav

    2014-01-01

    In living systems iron appears predominantly associated with proteins, but can also be detected in forms referred as labile iron, which denotes the combined redox properties of iron and its amenability to exchange between ligands, including chelators. The labile cell iron (LCI) composition varies with metal concentration and substances with chelating groups but also with pH and the medium redox potential. Although physiologically in the lower ?M range, LCI plays a key role in cell iron economy as cross-roads of metabolic pathways. LCI levels are continually regulated by an iron-responsive machinery that balances iron uptake versus deposition into ferritin. However, LCI rises aberrantly in some cell types due to faulty cell utilization pathways or infiltration by pathological iron forms that are found in hemosiderotic plasma. As LCI attains pathological levels, it can catalyze reactive O species (ROS) formation that, at particular threshold, can surpass cellular anti-oxidant capacities and seriously damage its constituents. While in normal plasma and interstitial fluids, virtually all iron is securely carried by circulating transferrin (Tf; that renders iron essentially non-labile), in systemic iron overload (IO), the total plasma iron binding capacity is often surpassed by a massive iron influx from hyperabsorptive gut or from erythrocyte overburdened spleen and/or liver. As plasma Tf approaches iron saturation, labile plasma iron (LPI) emerges in forms that can infiltrate cells by unregulated routes and raise LCI to toxic levels. Despite the limited knowledge available on LPI speciation in different types and degrees of IO, LPI measurements can be and are in fact used for identifying systemic IO and for initiating/adjusting chelation regimens to attain full-day LPI protection. A recent application of labile iron assay is the detection of labile components in intravenous iron formulations per se as well as in plasma (LPI) following parenteral iron administration. PMID:24659969

  15. Biotic and abiotic controls on diurnal fluctuations in labile soil phosphorus of a wet tropical forest.

    PubMed

    Vandecar, Karen L; Lawrence, Deborah; Wood, Tana; Oberbauer, Steven F; Das, Rishiraj; Tully, Katherine; Schwendenmann, Luitgard

    2009-09-01

    The productivity of many tropical wet forests is generally limited by bioavailable phosphorus (P). Microbial activity is a key regulator of P availability in that it determines both the supply of P through organic matter decomposition and the depletion of bioavailable P through microbial uptake. Both microbial uptake and mineralization occur rapidly, and their net effect on P availability varies with soil moisture, temperature, and soil organic matter quantity and quality. Exploring the mechanisms driving P availability at fine temporal scales can provide insight into the coupling of carbon, water, and nutrient cycles, and ultimately, the response of tropical forests to climate change. Despite the recognized importance of P cycling to the dynamics of wet tropical forests and their potential sensitivity to short-term fluctuations in bioavailable P, the diurnal pattern of P remains poorly understood. This study quantifies diurnal fluctuations in labile soil P and evaluates the importance of biotic and abiotic factors in driving these patterns. To this end, measurements of labile P were made every other hour in a Costa Rican wet tropical forest oxisol. Spatial and temporal variation in Bray-extractable P were investigated in relation to ecosystem carbon flux, soil CO2 efflux, soil moisture, soil temperature, solar radiation, and sap-flow velocity. Spatially averaged bi-hourly (every two hours) labile P ranged from 0.88 to 2.48 microg/g across days. The amplitude in labile P throughout the day was 0.61-0.82 microg/g (41-54% of mean P concentrations) and was characterized by a bimodal pattern with a decrease at midday. Labile P increased with soil CO2 efflux and soil temperature and declined with increasing sap flow and solar radiation. Together, soil CO2 efflux, soil temperature, and sap flow explained 86% of variation in labile P. PMID:19769132

  16. Labile carbon concentrations are strongly linked to plant production in Arctic tussock tundra soils

    NASA Astrophysics Data System (ADS)

    Darrouzet-Nardi, A.; Weintraub, M. N.; Euskirchen, E. S.; Steltzer, H.; Sullivan, P.

    2013-12-01

    The exchange of carbon and nutrients between plants and microbes is a key determinant of carbon balance in Arctic soils. Microbes rely on labile plant carbon for the energy they need to produce enzymes that can release nutrients and less energetically favorable carbon from soil organic matter. One of the main mechanisms of carbon transfer is rhizodeposition, the exudation of labile plant carbon such as sugars from roots into the rhizosphere. Despite the importance of this flow of energy and materials from plants to microbes, there have been few attempts to quantify labile carbon pools or fluxes in Arctic soils. To improve our knowledge of labile carbon dynamics in Arctic soils, we address two basic questions: (1) What are the seasonal patterns of labile carbon concentrations? and (2) How do seasonal patterns in labile carbon correlate with plant production, microbial biomass, and soil nutrients? We measured concentrations of total reducing sugars (TRS) in the soil solution of moist acidic tussock tundra on 28 dates during the 2012 growing season in 20 plots of an early snowmelt × warming experiment. We evaluated these total reducing sugar concentrations in the context of eddy flux carbon exchange data, plant NDVI, total dissolved carbon in soils, microbial biomass, and soil nutrients. Though we did not see treatment effects of the snowmelt × warming experiment, we did observe a clear seasonal pattern in TRS concentrations in which they started low at the time of thaw, then built to a maximum value around the time of peak plant physiology in July, followed by a decline as plants senesced. We observed a clear correlation between TRS and gross primary production (GPP). NDVI values also increased with TRS concentrations during the first half of the season and then leveled off as TRS began its decline. These relationships were in contrast to labile N concentrations, which remained at low concentrations all season. Our data suggest that rhizodeposition of labile carbon compounds in Arctic tundra ecosystems has a strong seasonal pattern that closely tracks plant production. This connection suggests that if plant production increases in a warmer Arctic, plants may ease carbon limitation to summer microbial activity.

  17. The role of labile iron in kidney disease and treatment with chelation.

    PubMed

    Shah, Sudhir V; Rajapurkar, Mohan M

    2009-01-01

    There are two major forms of kidney disease: acute renal failure [also referred to as acute kidney injury (AKI)] and chronic kidney disease (CKD). Acute renal failure is an abrupt loss of kidney function within 48 h, whereas CKD is a loss of kidney function greater than 3 months. There is a large amount of experimental evidence for an increase of labile iron in a wide variety of models of kidney disease. Additionally, iron chelators provide protection, indicating an important role of labile iron in these diseases. These observations suggest that iron chelators may provide a new modality of prevention and treatment of kidney disease. PMID:19821781

  18. Protective Immunity to Ricin Toxin Conferred by Antibodies against the Toxin’s Binding Subunit (RTB)

    PubMed Central

    Yermakova, Anastasiya; Mantis, Nicholas J.

    2011-01-01

    The B subunit (RTB) of ricin toxin is a galactose-/N-acetyl galactosamine-specific lectin that promotes attachment and entry of ricin into host cells. RTB is also the archetype of the so-called R-type lectin family, whose members include haemagglutinins of botulinum neurotoxin (BoNT) progenitor toxins, as well as the binding subunits of cytolethal distending toxins. Although RTB is an appealing subunit vaccine candidate, as well as a potential target for immunotherapeutics, the degree to which RTB immunization elicits protective antibodies against ricin toxin remains unresolved. To address this issue, groups of mice were immunized with RTB and then challenged with 5xLD50s of ricin administered intraperitoneally. Despite high RTB-specific serum antibody titers, groups of RTB immunized mice were only partially immune to ricin challenge. Analysis of a collection of RTB-specific B cell hybridomas suggested that only a small fraction of antibodies against RTB have demonstrable neutralizing activity. Two RTB-specific neutralizing monoclonal IgG1 antibodies, 24B11 and SylH3, when passively administered to mice, were sufficient to protect the animals against a 5xLD50 dose of ricin. Both 24B11 and SylH3 blocked ricin attachment to terminal galactose residues and prevented toxin binding to the surfaces of bone marrow-derived macrophages (BMM), suggesting that they function by steric hindrance and recognize epitopes located on RTB’s carbohydrate recognition sub-domains (1? or 2?). These data raise the possibility of using specific RTB sub-domains, rather than RTB itself, as antigens to more efficiently elicit neutralizing antibodies and protective immunity against ricin. PMID:21872634

  19. Detergent-inhibited, heat-labile nucleoside triphosphatase in cores of avian myeloblastosis virus.

    PubMed Central

    Jensen, K F

    1978-01-01

    Endogenous DNA synthesis was studied in isolated core particles of avian myeloblastosis virus. It was found that cores contained an enzymatic activity which rapidly converted the added nucleoside triphosphates to diphosphates (but not further) at 0 degrees C, thus inhibiting DNA synthesis. This triphosphatase probably originates from the viral membranes. In the cores the enzyme is completely inactivated by low concentrations (0.02%) of Nonident P-40. Also, the enzyme is very thermolabile and denatures rapidly at 38 degrees C. PMID:214571

  20. Exfoliative Toxins of Staphylococcus aureus

    PubMed Central

    Bukowski, Michal; Wladyka, Benedykt; Dubin, Grzegorz

    2010-01-01

    Staphylococcus aureus is an important pathogen of humans and livestock. It causes a diverse array of diseases, ranging from relatively harmless localized skin infections to life-threatening systemic conditions. Among multiple virulence factors, staphylococci secrete several exotoxins directly associated with particular disease symptoms. These include toxic shock syndrome toxin 1 (TSST-1), enterotoxins, and exfoliative toxins (ETs). The latter are particularly interesting as the sole agents responsible for staphylococcal scalded skin syndrome (SSSS), a disease predominantly affecting infants and characterized by the loss of superficial skin layers, dehydration, and secondary infections. The molecular basis of the clinical symptoms of SSSS is well understood. ETs are serine proteases with high substrate specificity, which selectively recognize and hydrolyze desmosomal proteins in the skin. The fascinating road leading to the discovery of ETs as the agents responsible for SSSS and the characterization of the molecular mechanism of their action, including recent advances in the field, are reviewed in this article. PMID:22069631

  1. An update on uremic toxins.

    PubMed

    Neirynck, N; Vanholder, R; Schepers, E; Eloot, S; Pletinck, A; Glorieux, G

    2013-02-01

    In the last decade, uremic toxicity as a potential cause for the excess of cardiovascular disease and mortality observed in chronic kidney disease gained more and more interest. This review focuses on uremic toxins with known cardiovascular effects and their removal. For protein-bound solutes, for example, indoxylsulfate and the conjugates of p-cresol, and for small water-soluble solutes, for example, guanidines, such as ADMA and SDMA, there is a growing evidence for a role in cardiovascular toxicity in vitro (e.g., affecting leukocyte, endothelial, vascular smooth muscle cell function) and/or in vivo. Several middle molecules (e.g., beta-2-microglobulin, interleukin-6, TNF-alpha and FGF-23) were shown to be predictors for cardiovascular disease and/or mortality. Most of these solutes, however, are difficult to remove during dialysis, which is traditionally assessed by studying the removal of urea, which can be considered as a relatively inert uremic retention solute. However, even the effective removal of other small water-soluble toxins than urea can be hampered by their larger distribution volumes. Middle molecules (beta-2-microglobulin as prototype, but not necessarily representative for others) are cleared more efficiently when the pore size of the dialyzer membrane increases, convection is applied and dialysis time is prolonged. Only adding convection to diffusion improves the removal of protein-bound toxins. Therefore, alternative removal strategies, such as intestinal adsorption, drugs interfering with toxic biochemical pathways or decreasing toxin concentration, and extracorporeal plasma adsorption, as well as kinetic behavior during dialysis need further investigation. Even more importantly, randomized clinical studies are required to demonstrate a survival advantage through these strategies. PMID:22893494

  2. Membrane translocation by anthrax toxin.

    PubMed

    Collier, R John

    2009-12-01

    Much attention has been focused on anthrax toxin recently, both because of its central role in the pathogenesis of Bacillus anthracis and because it has proven to be one of the most tractable toxins for studying how enzymic moieties of intracellularly acting toxins traverse membranes. The Protective Antigen (PA) moiety of the toxin, after being proteolytically activated at the cell surface, self-associates to form a heptameric pore precursor (prepore). The prepore binds up to three molecules of Edema Factor (EF), Lethal Factor (LF), or both, forming a series of complexes that are then endocytosed. Under the influence of acidic pH within the endosome, the prepore undergoes a conformational transition to a mushroom-shaped pore, with a globular cap and 100A-long stem that spans the membrane. Electrophysiological studies in planar bilayers indicate that EF and LF translocate through the pore in unfolded form and in the N- to C-terminal direction. The pore serves as an active transporter, which translocates its proteinaceous cargo across the endosomal membrane in response to DeltapH and perhaps, to a degree, Deltapsi. A ring of seven Phe residues (Phe427) in the lumen of the pore forms a seal around the translocating polypeptide and blocks the passage of ions, presumably preserving the pH gradient. A charge state-dependent Brownian ratchet mechanism has been proposed to explain how the pore translocates EF and LF. This transport mechanism of the pore may function in concert with molecular chaperonins to effect delivery of effector proteins in catalytically active form to the cytosolic compartment of host cells. PMID:19563824

  3. Enzymatically- and Ultraviolet-labile Phosphorus in Humic Acid Fractions From Rice Soils

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Humic acid is an important soil component which can improve nutrient availability and impact other important chemical, biological, and physical properties of soils. We investigated the lability of phosphorus (P) in the mobile humic acid (MHA) and calcium humate (CaHA) fractions of four rice soils as...

  4. Effects of Lability of Metal Complex on Free Ion Measurement Using DMT

    Microsoft Academic Search

    Liping Weng; Riemsdijk van W. H; Erwin J. M. Temminghoff

    2010-01-01

    Very low concentrations of free metal ion in natural samples can be measured using the Donnan membrane technique (DMT) based on ion transport kinetics. In this paper, the possible effects of slow dissociation of metal complexes on the interpretation of kinetic DMT are investigated both theoretically and experimentally. The expressions of the lability parameter, , were derived for DMT. Analysis

  5. Labile proteins accumulated in damaged hair upon permanent waving and bleaching treatments

    Microsoft Academic Search

    TAKAFUMI INOUE; MAYUMI ITO; KENJI KIZAWA

    We previously found that certain hair proteins were soluble by means of a partial extraction method. In this study, we demonstrate that the amount of soluble proteins internally formed in permed and bleached hair, labile proteins, is a useful index for hair damage assessment. Compared to tensile property changes, this index rose in widely dynamic ranges as the time of

  6. Labile plasma iron in iron overload: redox activity and susceptibility to chelation

    Microsoft Academic Search

    Breno P. Esposito; William Breuer; Pornpan Sirankapracha; Pensri Pootrakul; Chaim Hershko; Z. Ioav Cabantchik

    2003-01-01

    Plasma non-transferrin-bound-iron (NTBI) is believed to be responsible for cata- lyzing the formation of reactive radicals in the circulation of iron overloaded sub- jects, resulting in accumulation of oxida- tion products. We assessed the redox active component of NTBI in the plasma of healthy and -thalassemic patients. The labile plasma iron (LPI) was deter- mined with the fluorogenic dihydrorho- damine

  7. ORIGINAL PAPER Labile organic C and N mineralization of soil aggregate size

    E-print Network

    Yu, Qiang

    intensity is suggested. Keywords Soil organic carbon . Microbial biomass carbon . Dissolved organic carbon. Han State Key Laboratory of Forest and Soil Ecology, Institute of Applied Ecology, Chinese AcademyORIGINAL PAPER Labile organic C and N mineralization of soil aggregate size classes in semiarid

  8. Neutralising Antibodies against Ricin Toxin

    PubMed Central

    Prigent, Julie; Panigai, Laetitia; Lamourette, Patricia; Sauvaire, Didier; Devilliers, Karine; Plaisance, Marc; Volland, Hervé; Créminon, Christophe; Simon, Stéphanie

    2011-01-01

    The Centers for Disease Control and Prevention have listed the potential bioweapon ricin as a Category B Agent. Ricin is a so-called A/B toxin produced by plants and is one of the deadliest molecules known. It is easy to prepare and no curative treatment is available. An immunotherapeutic approach could be of interest to attenuate or neutralise the effects of the toxin. We sought to characterise neutralising monoclonal antibodies against ricin and to develop an effective therapy. For this purpose, mouse monoclonal antibodies (mAbs) were produced against the two chains of ricin toxin (RTA and RTB). Seven mAbs were selected for their capacity to neutralise the cytotoxic effects of ricin in vitro. Three of these, two anti-RTB (RB34 and RB37) and one anti-RTA (RA36), when used in combination improved neutralising capacity in vitro with an IC50 of 31 ng/ml. Passive administration of association of these three mixed mAbs (4.7 µg) protected mice from intranasal challenges with ricin (5 LD50). Among those three antibodies, anti-RTB antibodies protected mice more efficiently than the anti-RTA antibody. The combination of the three antibodies protected mice up to 7.5 hours after ricin challenge. The strong in vivo neutralising capacity of this three mAbs combination makes it potentially useful for immunotherapeutic purposes in the case of ricin poisoning or possibly for prevention. PMID:21633505

  9. Oxygen consumption and labile dissolved organic carbon uptake by benthic biofilms

    NASA Astrophysics Data System (ADS)

    de Falco, Natalie; Boano, Fulvio; Arnon, Shai

    2015-04-01

    Biogeochemical activity in streams is often magnified at interfaces, such as in the case of biofilm growth near the surface of the stream sediments. The objective of this study was to evaluate the relative importance of surficial biofilms versus the biofilm in the hyporheic zone to the processes of biodegradation of a labile dissolved organic carbon (DOC) and to oxygen consumption. Experiments were conducted in a recirculating flume, equipped with a drainage system that enables the control on losing and gaining fluxes. A surficial biofilm was developed over a sandy streambed with dune-shaped bed forms, by providing labile DOC (sodium benzoate) and nitrate. Homogeneously distributed biofilm was obtained by the same feeding strategy but with mixing the sediments manually on a daily basis. After the biofilm growth period, transformation of the labile DOC under different overlying velocities and losing or gaining fluxes was studied after spiking with sodium benzoate and by monitoring the decrease in DOC concentration in the bulk water over time using an online UV/Vis spectrophotometer. In addition, oxygen profiles across the water-streambed interface were measured at different locations along the bed form using oxygen microelectrodes. Preliminary results showed that the rate of labile DOC degradation increased exponentially with increasing overlying water velocity, regardless of the type of biofilm. Gaining and losing conditions did not play a critical role in the DOC degradation regardless of the type of biofilm, because the labile DOC was quickly utilized close to the surface. Under losing conditions, complete depletion of oxygen was observed within the top 5 millimeters, regardless of the biofilm type. In contrast, oxygen profiles under gaining condition showed an incomplete consumption of oxygen followed by an increase in the concentration of oxygen deeper in the sediments due to the upward flow of oxygenated groundwater. The results suggest that the transformation of labile DOC occurs in the upper millimeters of the streambed, and the size and shape of the hyporheic flow paths are less important for aerobic activity. In addition, the effect of overlying water velocity on labile DOC transformation was shown to be more influential than losing and gaining fluxes.

  10. Bt Toxin Modification for Enhanced Efficacy

    PubMed Central

    Deist, Benjamin R.; Rausch, Michael A.; Fernandez-Luna, Maria Teresa; Adang, Michael J.; Bonning, Bryony C.

    2014-01-01

    Insect-specific toxins derived from Bacillus thuringiensis (Bt) provide a valuable resource for pest suppression. Here we review the different strategies that have been employed to enhance toxicity against specific target species including those that have evolved resistance to Bt, or to modify the host range of Bt crystal (Cry) and cytolytic (Cyt) toxins. These strategies include toxin truncation, modification of protease cleavage sites, domain swapping, site-directed mutagenesis, peptide addition, and phage display screens for mutated toxins with enhanced activity. Toxin optimization provides a useful approach to extend the utility of these proteins for suppression of pests that exhibit low susceptibility to native Bt toxins, and to overcome field resistance. PMID:25340556

  11. Bt toxin modification for enhanced efficacy.

    PubMed

    Deist, Benjamin R; Rausch, Michael A; Fernandez-Luna, Maria Teresa; Adang, Michael J; Bonning, Bryony C

    2014-10-01

    Insect-specific toxins derived from Bacillus thuringiensis (Bt) provide a valuable resource for pest suppression. Here we review the different strategies that have been employed to enhance toxicity against specific target species including those that have evolved resistance to Bt, or to modify the host range of Bt crystal (Cry) and cytolytic (Cyt) toxins. These strategies include toxin truncation, modification of protease cleavage sites, domain swapping, site-directed mutagenesis, peptide addition, and phage display screens for mutated toxins with enhanced activity. Toxin optimization provides a useful approach to extend the utility of these proteins for suppression of pests that exhibit low susceptibility to native Bt toxins, and to overcome field resistance. PMID:25340556

  12. In vitro evaluation of the cytotoxic, hemolytic and clastogenic activities of Rhizostoma pulmo toxin(s).

    PubMed

    Allavena, A; Mariottini, G L; Carli, A M; Contini, S; Martelli, A

    1998-06-01

    Cytotoxic, hemolytic and clastogenic activities of Rhizostoma pulmo toxin(s) contained in the jelly tissue free of nematocysts were investigated in mammalian cells with in vitro procedures. At the concentration of 37.6 microg/ml the tissue protein produced the death of 50% V79 cells; a similar potency was observed in terms of hemolytic activity. The toxin(s) was not clastogenic for human lymphocytes in culture at the concentration of 5 microg/ml. PMID:9663699

  13. Cellular and systemic effects of anthrax lethal toxin and edema toxin.

    PubMed

    Moayeri, Mahtab; Leppla, Stephen H

    2009-12-01

    Anthrax lethal toxin (LT) and edema toxin (ET) are the major virulence factors of anthrax and can replicate the lethality and symptoms associated with the disease. This review provides an overview of our current understanding of anthrax toxin effects in animal models and the cytotoxicity (necrosis and apoptosis) induced by LT in different cells. A brief reexamination of early historic findings on toxin in vivo effects in the context of our current knowledge is also presented. PMID:19638283

  14. Prokaryotic toxin–antitoxin stress response loci

    Microsoft Academic Search

    Susanne K. Christensen; Anders Løbner-Olesen; Kenn Gerdes

    2005-01-01

    Although toxin–antitoxin gene cassettes were first found in plasmids, recent database mining has shown that these loci are abundant in free-living prokaryotes, including many pathogenic bacteria. For example, Mycobacterium tuberculosis has 38 chromosomal toxin–antitoxin loci, including 3 relBE and 9 mazEF loci. RelE and MazF are toxins that cleave mRNA in response to nutritional stress. RelE cleaves mRNAs that are

  15. Geldanamycin Enhances Retrograde Transport of Shiga Toxin in HEp-2 Cells

    PubMed Central

    Simm, Roger; Torgersen, Maria Lyngaas; Sandvig, Kirsten

    2015-01-01

    The heat shock protein 90 (Hsp90) inhibitor geldanamycin (GA) has been shown to alter endosomal sorting, diverting cargo destined for the recycling pathway into the lysosomal pathway. Here we investigated whether GA also affects the sorting of cargo into the retrograde pathway from endosomes to the Golgi apparatus. As a model cargo we used the bacterial toxin Shiga toxin, which exploits the retrograde pathway as an entry route to the cytosol. Indeed, GA treatment of HEp-2 cells strongly increased the Shiga toxin transport to the Golgi apparatus. The enhanced Golgi transport was not due to increased endocytic uptake of the toxin or perturbed recycling, suggesting that GA selectively enhances endosomal sorting into the retrograde pathway. Moreover, GA activated p38 and both inhibitors of p38 or its substrate MK2 partially counteracted the GA-induced increase in Shiga toxin transport. Thus, our data suggest that GA-induced p38 and MK2 activation participate in the increased Shiga toxin transport to the Golgi apparatus. PMID:26017782

  16. Cellular and systemic effects of anthrax lethal toxin and edema toxin

    Microsoft Academic Search

    Mahtab Moayeri; Stephen H. Leppla

    2009-01-01

    Anthrax lethal toxin (LT) and edema toxin (ET) are the major virulence factors of anthrax and can replicate the lethality and symptoms associated with the disease. This review provides an overview of our current understanding of anthrax toxin effects in animal models and the cytotoxicity (necrosis and apoptosis) induced by LT in different cells. A brief reexamination of early historic

  17. TOXINS IN BIOTECHNOLOGY / 1 Animal Toxins in the World of Modern

    E-print Network

    Paris-Sud XI, Université de

    TOXINS IN BIOTECHNOLOGY / 1 Animal Toxins in the World of Modern Biotechnology JEAN-MARC SABATIER1 Biotechnologies, Bâtiment Biopolis, 5, avenue du Grand Sablon, 38700 La Tronche, France. Tel.: +33-4-56520563; Fax: +33-4-56520637; E-mail address: michel.dewaard@ujf-grenoble.fr Running title: Toxins in Biotechnology

  18. Dissolved organic carbon lability increases with water residence time in the alluvial aquifer of a river floodplain ecosystem

    NASA Astrophysics Data System (ADS)

    Helton, Ashley M.; Wright, Meredith S.; Bernhardt, Emily S.; Poole, Geoffrey C.; Cory, Rose M.; Stanford, Jack A.

    2015-04-01

    We assessed spatial and temporal patterns of dissolved organic carbon (DOC) lability and composition throughout the alluvial aquifer of the 16 km2 Nyack Floodplain in northwest Montana, USA. Water influx to the aquifer derives almost exclusively from the Middle Fork of the Flathead River, and water residence times within the aquifer range from days to months. Across seasons and channel discharge conditions, we measured DOC concentration, lability, and optical properties of aquifer water sampled from 12 wells, both near and ~3 m below the water table. Concentrations of DOC were typically low (542 ± 22.7 µg L-1; mean ± se), and the percentage of labile DOC averaged 18 ± 12% during 3 day laboratory assays. Parallel factor analysis of fluorescence excitation-emission matrices revealed two humic-like and two amino acid-like fluorescence groups. Total DOC, humic-like components, and specific UV absorbance decreased with water residence time, consistent with sorption to aquifer sediments. However, labile DOC (both concentration and fraction) increased with water residence time, suggesting a concurrent influx or production of labile DOC. Thus, although the carbon-poor, oxygen-rich aquifer is a net sink for DOC, recalcitrant DOC appears to be replaced with more labile DOC along aquifer flow paths. Our observation of DOC production in long flow paths contrasts with studies of hyporheic DOC consumption along short (centimeters to meters) flow paths and highlights the importance of understanding the role of labile organic matter production and/or influx in alluvial aquifer carbon cycling.

  19. Quantitative Fecal Lactoferrin in Toxin-Positive and Toxin-Negative Clostridium difficile Specimens

    PubMed Central

    Ekhmimi, Tariq; Hill, A. Kate; Farooqi, Imran; Perrotta, Peter L.

    2013-01-01

    Quantitative fecal lactoferrin was measured in 112 patients tested for toxigenic Clostridium difficile using glutamate dehydrogenase (GDH) and toxin immunoassays combined with tcdB PCR. Lactoferrin levels were higher in the GDH-positive/toxin-positive group (79 ?g/ml) than in the GDH-positive/toxin-negative/PCR-positive (21 ?g/ml) and the GDH-negative groups (13 ?g/ml). Differences in fecal lactoferrin levels suggest variable presence or severity of C. difficile infection among toxin-positive and toxin-negative patients. PMID:23135940

  20. Microwave heating inactivates Shiga Toxin (Stx2) in pH 7.4 buffer and in reconstituted fat-free Milk and adversely affects the nutritional value of cell culture medium

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Microwave exposure is a convenient and widely used method for defrosting, heating, and cooking numerous foods. Microwave cooking is also reported to kill pathogenic microorganisms that often contaminate food. Microwaves act by causing polar molecules in food, such as water, to rapidly rotate, thus...

  1. Botulinum toxin: The Midas touch

    PubMed Central

    Shilpa, P. S.; Kaul, Rachna; Sultana, Nishat; Bhat, Suraksha

    2014-01-01

    Botulinum Toxin (BT) is a natural molecule produced during growth and autolysis of bacterium called Clostridium botulinum. Use of BT for cosmetic purposes has gained popularity over past two decades, and recently, other therapeutic uses of BT has been extensively studied. BT is considered as a minimally invasive agent that can be used in the treatment of various orofacial disorders and improving the quality of life in such patients. The objective of this article is to review the nature, mechanism of action of BT, and its application in various head and neck diseases. PMID:24678189

  2. Designing Inhibitors of Anthrax Toxin

    PubMed Central

    Nestorovich, Ekaterina M.; Bezrukov, Sergey M.

    2014-01-01

    Introduction Present-day rational drug design approaches are based on exploiting unique features of the target biomolecules, small- or macromolecule drug candidates, and physical forces that govern their interactions. The 2013 Nobel Prize in chemistry awarded “for the development of multiscale models for complex chemical systems” once again demonstrated the importance of the tailored drug discovery that reduces the role of the trial and error approach to a minimum. The “rational drug design” term is rather comprehensive as it includes all contemporary methods of drug discovery where serendipity and screening are substituted by the information-guided search for new and existing compounds. Successful implementation of these innovative drug discovery approaches is inevitably preceded by learning the physics, chemistry, and physiology of functioning of biological structures under normal and pathological conditions. Areas covered This article provides an overview of the recent rational drug design approaches to discover inhibitors of anthrax toxin. Some of the examples include small-molecule and peptide-based post-exposure therapeutic agents as well as several polyvalent compounds. The review also directs the reader to the vast literature on the recognized advances and future possibilities in the field. Expert opinion Existing options to combat anthrax toxin lethality are limited. With the only anthrax toxin inhibiting therapy (PA-targeting with a monoclonal antibody, raxibacumab) approved to treat inhalational anthrax, in our view, the situation is still insecure. The FDA’s animal rule for drug approval, which clears compounds without validated efficacy studies on humans, creates a high level of uncertainty, especially when a well-characterized animal model does not exist. Besides, unlike PA, which is known to be unstable, LF remains active in cells and in animal tissues for days. Therefore, the effectiveness of the post-exposure treatment of the individuals with anti-PA therapeutics can be time-dependent, requiring coordinated use of membrane permeable small-molecule inhibitors, which block the LF and EF enzymatic activity intracellularly. The desperate search for an ideal anthrax antitoxin allowed researchers to gain important knowledge of the basic principles of small-molecule interactions with their protein targets that could be easily transferred to other systems. At the same time, better identification and validation of anthrax toxin therapeutic targets at the molecular level, which include understanding of the physical forces underlying the target/drug interaction, as well as elucidation of the parameters determining the corresponding therapeutic windows, require further examination. PMID:24447197

  3. Strengthening the Biological and Toxin Weapons Convention

    E-print Network

    Sussex, University of

    Strengthening the Biological and Toxin Weapons Convention: Countering the Threat from Biological Weapons Presented to Parliament by the Secretary of State for Foreign and Commonwealth Affairs By Command of Her Majesty April 2002 Cm 5484 £5.00 #12;3 STRENGTHENING THE BIOLOGICAL AND TOXIN WEAPONS CONVENTION

  4. The roles of anthrax toxin in pathogenesis

    Microsoft Academic Search

    Mahtab Moayeri; Stephen H Leppla

    2004-01-01

    Anthrax lethal toxin is a multi-functional virulence factor that has evolved to target multiple host functions to allow for optimal establishment of Bacillus anthracis infection. The toxin appears to play a role in all stages of infection, from germination to the induction of vascular collapse leading to host death. Early in infection, at sublethal doses, it acts to suppress immune

  5. Human genetic variation altering anthrax toxin sensitivity

    E-print Network

    Tang, Hua

    Human genetic variation altering anthrax toxin sensitivity Mikhail Martchenkoa , Sophie I for review October 31, 2011) The outcome of exposure to infectious microbes or their toxins is influenced affecting capillary morphogenesis gene 2 (CMG2), which encodes a host membrane protein exploited by anthrax

  6. The toxin component of targeted anti-tumor toxins determines their efficacy increase by saponins.

    PubMed

    Weng, Alexander; Thakur, Mayank; Beceren-Braun, Figen; Bachran, Diana; Bachran, Christopher; Riese, Sebastian B; Jenett-Siems, Kristina; Gilabert-Oriol, Roger; Melzig, Matthias F; Fuchs, Hendrik

    2012-06-01

    Tumor-targeting protein toxins are composed of a toxic enzyme coupled to a specific cell binding domain that targets cancer-associated antigens. The anti-tumor treatment by targeted toxins is accompanied by dose-limiting side effects. The future prospects of targeted toxins for therapeutic use in humans will be determined by reduce side effects. Certain plant secondary metabolites (saponins) were shown to increase the efficacy of a particular epidermal growth factor receptor (EGFR)-targeted toxin, paralleled by a tremendous decrease of side effects. This study was conducted in order to investigate the effects of substituting different toxin moieties fused to an EGF ligand binding domain on the augmentative ability of saponins for each against therapeutic potential of the saponin-mediated efficacy increase for different anti-tumor toxins targeting the EGFR. We designed several EGFR-targeted toxins varying in the toxic moiety. Each targeted toxin was used in combination with a purified saponin (SA1641), isolated from the ornamental plant Gypsophila paniculata L. SA1641 was characterized and the SA1641-mediated efficacy increase was investigated on EGFR-transfected NIH-3T3 cells. We observed a high dependency of the SA1641-mediated efficacy increase on the nature of toxin used for the construction of the targeted toxin, indicating high specificity. Structural alignments revealed a high homology between saporin and dianthin-30, the two toxic moieties that benefit most from the combination with SA1641. We further demonstrate that SA1641 did not influence the plasma membrane permeability, indicating an intracellular interaction of SA1641 and the toxin components of targeted toxins. Surface plasmon resonance measurements point to a transient binding of SA1641 to the toxin components of targeted toxins. PMID:22309811

  7. Brown spider dermonecrotic toxin directly induces nephrotoxicity

    SciTech Connect

    Chaim, Olga Meiri [Department of Cell Biology, Federal University of Parana, Jardim das Americas, 81531-990, Curitiba, Parana (Brazil); Sade, Youssef Bacila [Department of Cell Biology, Federal University of Parana, Jardim das Americas, 81531-990, Curitiba, Parana (Brazil); Bertoni da Silveira, Rafael [Department of Biochemistry, Federal University of Sao Paulo, Sao Paulo (Brazil); Toma, Leny [Department of Biochemistry, Federal University of Sao Paulo, Sao Paulo (Brazil); Kalapothakis, Evanguedes [Department of Pharmacology, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais (Brazil); Chavez-Olortegui, Carlos [Department of Biochemistry and Immunology, Federal University of Minas Gerais, Belo Horizonte, Minas Gerais (Brazil); Mangili, Oldemir Carlos [Department of Physiology, Federal University of Parana, Curitiba, Parana (Brazil); Gremski, Waldemiro [Department of Cell Biology, Federal University of Parana, Jardim das Americas, 81531-990, Curitiba, Parana (Brazil); Catholic University of Parana, Health and Biological Sciences Institute, Curitiba, Parana (Brazil); Dietrich, Carl Peter von [Department of Biochemistry, Federal University of Sao Paulo, Sao Paulo (Brazil); Nader, Helena B. [Department of Biochemistry, Federal University of Sao Paulo, Sao Paulo (Brazil); Sanches Veiga, Silvio [Department of Cell Biology, Federal University of Parana, Jardim das Americas, 81531-990, Curitiba, Parana (Brazil)]. E-mail: veigass@ufpr.br

    2006-02-15

    Brown spider (Loxosceles genus) venom can induce dermonecrotic lesions at the bite site and systemic manifestations including fever, vomiting, convulsions, disseminated intravascular coagulation, hemolytic anemia and acute renal failure. The venom is composed of a mixture of proteins with several molecules biochemically and biologically well characterized. The mechanism by which the venom induces renal damage is unknown. By using mice exposed to Loxosceles intermedia recombinant dermonecrotic toxin (LiRecDT), we showed direct induction of renal injuries. Microscopic analysis of renal biopsies from dermonecrotic toxin-treated mice showed histological alterations including glomerular edema and tubular necrosis. Hyalinization of tubules with deposition of proteinaceous material in the tubule lumen, tubule epithelial cell vacuoles, tubular edema and epithelial cell lysis was also observed. Leukocytic infiltration was neither observed in the glomerulus nor the tubules. Renal vessels showed no sign of inflammatory response. Additionally, biochemical analyses showed such toxin-induced changes in renal function as urine alkalinization, hematuria and azotemia with elevation of blood urea nitrogen levels. Immunofluorescence with dermonecrotic toxin antibodies and confocal microscopy analysis showed deposition and direct binding of this toxin to renal intrinsic structures. By immunoblotting with a hyperimmune dermonecrotic toxin antiserum on renal lysates from toxin-treated mice, we detected a positive signal at the region of 33-35 kDa, which strengthens the idea that renal failure is directly induced by dermonecrotic toxin. Immunofluorescence reaction with dermonecrotic toxin antibodies revealed deposition and binding of this toxin directly in MDCK epithelial cells in culture. Similarly, dermonecrotic toxin treatment caused morphological alterations of MDCK cells including cytoplasmic vacuoles, blebs, evoked impaired spreading and detached cells from each other and from culture substratum. In addition, dermonecrotic toxin treatment of MDCK cells changed their viability evaluated by XTT and Neutral-Red Uptake methodologies. The present results point to brown spider dermonecrotic toxin cytotoxicity upon renal structures in vivo and renal cells in vitro and provide experimental evidence that this brown spider toxin is directly involved in nephrotoxicity evoked during Loxosceles spider venom accidents.

  8. Crystallization of isoelectrically homogeneous cholera toxin

    SciTech Connect

    Spangler, B.D.; Westbrook, E.M. (Argonne National Laboratory, IL (USA))

    1989-02-07

    Past difficulty in growing good crystals of cholera toxin has prevented the study of the crystal structure of this important protein. The authors have determined that failure of cholera toxin to crystallize well has been due to its heterogeneity. They have now succeeded in overcoming the problem by isolating a single isoelectric variant of this oligomeric protein (one A subunit and five B subunits). Cholera toxin purified by their procedure readily forms large single crystals. The crystal form has been described previously. They have recorded data from native crystals of cholera toxin to 3.0-{angstrom} resolution with our electronic area detectors. With these data, they have found the orientation of a 5-fold symmetry axis within these crystals, perpendicular to the screw dyad of the crystal. They are now determining the crystal structure of cholera toxin by a combination of multiple heavy-atom isomorphous replacement and density modification techniques, making use of rotational 5-fold averaging of the B subunits.

  9. Identification and purification of target protein using affinity resin bearing a photo-labile linker.

    PubMed

    Mabuchi, Miyuki; Shimizu, Tadashi; Haramura, Masayuki; Tanaka, Akito

    2015-08-15

    This Letter presents an effective method for the identification of target proteins of bioactive compounds such as drugs, natural products, and intrinsic ligands, using an affinity resin. The application of a photo-labile linker to an affinity resin enabled the selective elution of a target protein by irradiation for a short duration at 4°C while leaving a large amount of non-specific binding protein on the resin. We have named this method the 'STEAP' method (selective target elution from affinity resins with photo-labile linker). Only a target protein that can bind the bioactive compound, the so-called 'active' protein, is eluted by the selective cleavage of the linker between the solid matrix and the target compound, and therefore, it is worth considering the potential of this method for the hyper-purification of proteins. PMID:26099537

  10. Purification and characterization of an oxygen-labile, NAD-dependent alcohol dehydrogenase from Desulfovibrio gigas.

    PubMed Central

    Hensgens, C M; Vonck, J; Van Beeumen, J; van Bruggen, E F; Hansen, T A

    1993-01-01

    A NAD-dependent, oxygen-labile alcohol dehydrogenase was purified from Desulfovibrio gigas. It was decameric, with subunits of M(r) 43,000. The best substrates were ethanol (Km, 0.15 mM) and 1-propanol (Km, 0.28 mM). N-terminal amino acid sequence analysis showed that the enzyme belongs to the same family of alcohol dehydrogenases as Zymomonas mobilis ADH2 and Bacillus methanolicus MDH. Images PMID:8491707

  11. Mayolenes: Labile defensive lipids from the glandular hairs of a caterpillar (Pieris rapae)

    PubMed Central

    Smedley, Scott R.; Schroeder, Frank C.; Weibel, Douglas B.; Meinwald, Jerrold; Lafleur, Katie A.; Renwick, J. Alan; Rutowski, Ronald; Eisner, Thomas

    2002-01-01

    Larvae of the European cabbage butterfly, Pieris rapae (Pieridae), are beset with glandular hairs, bearing droplets of a clear oily secretion at their tip. The fluid consists primarily of a series of chemically labile, unsaturated lipids, the mayolenes, which are derived from 11-hydroxylinolenic acid. In bioassays with the ant Crematogaster lineolata, the secretion was shown to be potently deterrent, indicating that the fluid plays a defensive role in nature. PMID:11997469

  12. Tillage and liming effects on crop and labile soil nitrogen in an acid soil

    Microsoft Academic Search

    Y. K. Soon; M. A. Arshad

    2005-01-01

    Limited information is available on soil management effects on crop production and nitrogen (N) cycling in acid soils. The effects of conventional tillage (CT) versus no-till (NT) and liming (0 versus 7.5Mgha?1), and their interaction, on labile N pools in an acid soil were evaluated during the 7th to 10th year of a 3-course small grain rotation. Crop production and

  13. Effects of labile soil carbon on nutrient partitioning between an arctic graminoid and microbes

    Microsoft Academic Search

    Inger K. Schmidt; Anders Michelsen; Sven Jonasson

    1997-01-01

    We measured partitioning of N and P uptake between soil microorganisms and potted Festuca vivipara in soil from a subarctic heath in response to factorial addition of three levels of labile carbon (glucose) combined with\\u000a two levels of inorganic N and P. The glucose was added to either non-sterilized or sterilized (autoclaved) soils in quantities\\u000a which were within the range

  14. Labile and stabilised fractions of soil organic carbon in some intensively cultivated alluvial soils.

    PubMed

    Verma, B C; Datta, S P; Rattan, R K; Singh, A K

    2013-11-01

    The present investigation was undertaken in view of the limited information on the relative proportion of labile and stabilized fractions of soil organic carbon (SOC) in intensively cultivated lands, particularly under tropics. The specific objectives were i) to study the comparative recovery of SOC by different methods of labile carbon estimation under intensively cultivated lands and ii) to evaluate the impact of agricultural practices on carbon management index. For this purpose, in all, 105 surface soil samples were collected from intensively cultivated tube well and sewage irrigated agricultural lands. These samples were analysed for total as well as labile pools of SOC. Results indicated that Walkley and Black, KMnO4-oxidizable and microbial biomass carbon constituted the total SOC to the extent of 10.2 to 47.4, 1.66 to 23.2 and 0.30 to 5.49%, respectively with the corresponding mean values of 26.2, 9.16 and 2.15%. Lability of SOC was considerably higher in sewage irrigated soils than tube well irrigated soils under intensive cropping. Under soybean-wheat, the higher values of carbon management index (CMI) (279 and 286) were associated with the treatments where entire amount of nitrogen was supplied through FYM. Similar results were obtained under rice-wheat, whereas in case of maize-wheat the highest value of CMI was recorded under treatment receiving NPK through chemical fertilizer along with green manure. There was also a significant improvement in CMI under integrated (chemical fertilizer + organics) and chemical fertilizer-treated plots. The values of CMI ranged from 220 to 272 under cultivated lands receiving irrigation through sewage and industrial effluents. PMID:24555339

  15. Comparison of metal lability in air-dried and fresh dewatered drinking water treatment residuals.

    PubMed

    Wang, Changhui; Pei, Yuansheng; Zhao, Yaqian

    2015-01-01

    In this work, the labilities of Al, As, Ba, Be, Ca, Cd, Co, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Pb, Sr, V and Zn in air-dried (for 60 days) and fresh dewatered WTRs were compared using the Toxicity Characteristic Leaching Procedure (TCLP), fractionation, in vitro digestion and a plant enrichment test. The results showed that the air-dried and fresh dewatered WTRs had different properties, e.g., organic matter composition and available nutrients. The air-dried and fresh dewatered WTRs were non-haf zardous according to the TCLP assessment method used in the United States; however, the metals in the two types of WTRs had different lability. Compared with the metals in the fresh dewatered WTRs, those in the air-dried WTRs tended to be in more stable fractions and also exhibited lower bioaccessibility and bioavailability. Therefore, air-drying can decrease the metal lability and thereby reduce the potential metal pollution risk of WTRs. PMID:25560259

  16. Evolution of phenotypic plasticity and environmental tolerance of a labile quantitative character in a fluctuating environment.

    PubMed

    Lande, R

    2014-05-01

    Quantitative genetic models of evolution of phenotypic plasticity are used to derive environmental tolerance curves for a population in a changing environment, providing a theoretical foundation for integrating physiological and community ecology with evolutionary genetics of plasticity and norms of reaction. Plasticity is modelled for a labile quantitative character undergoing continuous reversible development and selection in a fluctuating environment. If there is no cost of plasticity, a labile character evolves expected plasticity equalling the slope of the optimal phenotype as a function of the environment. This contrasts with previous theory for plasticity influenced by the environment at a critical stage of early development determining a constant adult phenotype on which selection acts, for which the expected plasticity is reduced by the environmental predictability over the discrete time lag between development and selection. With a cost of plasticity in a labile character, the expected plasticity depends on the cost and on the environmental variance and predictability averaged over the continuous developmental time lag. Environmental tolerance curves derived from this model confirm traditional assumptions in physiological ecology and provide new insights. Tolerance curve width increases with larger environmental variance, but can only evolve within a limited range. The strength of the trade-off between tolerance curve height and width depends on the cost of plasticity. Asymmetric tolerance curves caused by male sterility at high temperature are illustrated. A simple condition is given for a large transient increase in plasticity and tolerance curve width following a sudden change in average environment. PMID:24724972

  17. Memory labilization in reconsolidation and extinction--evidence for a common plasticity system?

    PubMed

    Almeida-Corrêa, Suellen; Amaral, Olavo B

    2014-01-01

    Reconsolidation and extinction are two processes occurring upon memory retrieval that have received great attention in memory research over the last decade, partly due to their purported potential in the treatment of anxiety disorders. Due to their opposite behavioral effects, the two phenomena have usually been considered as separate entities, with few attempts to build a unified view of how both could be produced by similar mechanisms. Based on computational modeling, we have previously proposed that reconsolidation and extinction are behavioral outcomes of the same set of plasticity systems, albeit working at different synapses. One of these systems seems to be pharmacologically similar to the one involved in initial memory consolidation, and likely involves traditional Hebbian plasticity, while the second seems to be more involved with the labilization of existing memories and/or synaptic changes. In this article, we review the evidence for the existence of a plasticity system specifically involved in memory labilization, as well as its possible molecular requirements, anatomical substrates, synaptic mechanisms and physiological roles. Based on these data, we propose that the field of memory updating might ultimately benefit from a paradigm shift in which reconsolidation and extinction are viewed not as separate processes but as different instantiations of plasticity systems responsible for reinforcement and labilization of synaptic changes. PMID:25173958

  18. Bacillithiol is a major buffer of the labile zinc pool in Bacillus subtilis.

    PubMed

    Ma, Zhen; Chandrangsu, Pete; Helmann, Tyler C; Romsang, Adisak; Gaballa, Ahmed; Helmann, John D

    2014-11-01

    Intracellular zinc levels are tightly regulated since zinc is an essential cofactor for numerous enzymes, yet can be toxic when present in excess. The majority of intracellular zinc is tightly associated with proteins and is incorporated during synthesis from a poorly defined pool of kinetically labile zinc. In Bacillus subtilis, this labile pool is sensed by equilibration with the metalloregulator Zur, as an indication of zinc sufficiency, and by CzrA, as an indication of zinc excess. Here, we demonstrate that the low-molecular-weight thiol bacillithiol (BSH) serves as a major buffer of the labile zinc pool. Upon shift to conditions of zinc excess, cells transiently accumulate zinc in a low-molecular-weight pool, and this accumulation is largely dependent on BSH. Cells lacking BSH are more sensitive to zinc stress, and they induce zinc efflux at lower external zinc concentrations. Thiol reactive agents such as diamide and cadmium induce zinc efflux by interfering with the Zn-buffering function of BSH. Our data provide new insights into intracellular zinc buffering and may have broad relevance given the presence of BSH in pathogens and the proposed role of zinc sequestration in innate immunity. PMID:25213752

  19. Toxins

    MedlinePLUS

    Ford MD. Acute poisoning. In: Goldman L, Schafer AI, eds. Cecil Medicine . 24th ed. Philadelphia, Pa: Saunders ... trace metals and others. In: Goldman L, Schafer AI, eds. Cecil Medicine . 24th ed. Philadelphia, Pa: Saunders ...

  20. MATERIALS FOR BINDING MYCOTOXINS AND THEIR USE IN TOXIN DETECTION

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Materials capable of binding mycotoxins find numerous uses. These include components of test kits for toxin detection, as agents for isolation of toxins from foods or toxin purification, and as binding agents to prevent toxin uptake and thereby protect domestic animals. There is no shortage of mat...

  1. Detection of a cytolytic toxin in the venom of the stonefish (Synanceia trachynis).

    PubMed

    Kreger, A S

    1991-01-01

    The venom of the stonefish, Synanceia trachynis, contains a cytolytic toxin which is antigenic and ammonium sulfate-precipitable, and has a pI of ca 5.7 and an Mr of ca 158,000. The toxin is a potent but narrow-spectrum cytolysin which is lytic in vitro for rabbit, dog, rat, and guinea pig erythrocytes, in that order, but is largely or completely inactive against sheep, cow, human, monkey, mouse, goat, horse, burro and cat erythrocytes. Fractionation of the venom by molecular sieve fast protein liquid chromatography and isoelectric focusing did not separate the haemolytic activity from the venom's lethal and vascular permeability-increasing activities. Also, the three activities were destroyed by heat, proteases, Congo red, potassium permanganate and stonefish antivenoms. The results suggest that the haemolytic, lethal and vascular permeability-increasing activities of stonefish venom are properties of the same molecule, a previously unrecognized, membrane-damaging protein toxin. PMID:1926174

  2. Cyanobacterial toxins: risk management for health protection.

    PubMed

    Codd, Geoffrey A; Morrison, Louise F; Metcalf, James S

    2005-03-15

    This paper reviews the occurrence and properties of cyanobacterial toxins, with reference to the recognition and management of the human health risks which they may present. Mass populations of toxin-producing cyanobacteria in natural and controlled waterbodies include blooms and scums of planktonic species, and mats and biofilms of benthic species. Toxic cyanobacterial populations have been reported in freshwaters in over 45 countries, and in numerous brackish, coastal, and marine environments. The principal toxigenic genera are listed. Known sources of the families of cyanobacterial toxins (hepato-, neuro-, and cytotoxins, irritants, and gastrointestinal toxins) are briefly discussed. Key procedures in the risk management of cyanobacterial toxins and cells are reviewed, including derivations (where sufficient data are available) of tolerable daily intakes (TDIs) and guideline values (GVs) with reference to the toxins in drinking water, and guideline levels for toxigenic cyanobacteria in bathing waters. Uncertainties and some gaps in knowledge are also discussed, including the importance of exposure media (animal and plant foods), in addition to potable and recreational waters. Finally, we present an outline of steps to develop and implement risk management strategies for cyanobacterial cells and toxins in waterbodies, with recent applications and the integration of Hazard Assessment Critical Control Point (HACCP) principles. PMID:15737680

  3. Clostridium difficile: its disease and toxins.

    PubMed Central

    Lyerly, D M; Krivan, H C; Wilkins, T D

    1988-01-01

    Clostridium difficile is the etiologic agent of pseudomembranous colitis, a severe, sometimes fatal disease that occurs in adults undergoing antimicrobial therapy. The disease, ironically, has been most effectively treated with antibiotics, although some of the newer methods of treatment such as the replacement of the bowel flora may prove more beneficial for patients who continue to relapse with pseudomembranous colitis. The organism produces two potent exotoxins designated toxin A and toxin B. Toxin A is an enterotoxin believed to be responsible for the diarrhea and mucosal tissue damage which occur during the disease. Toxin B is an extremely potent cytotoxin, but its role in the disease has not been as well studied. There appears to be a cascade of events which result in the expression of the activity of these toxins, and these events, ranging from the recognition of a trisaccharide receptor by toxin A to the synergistic action of the toxins and their possible dissemination in the body, are discussed in this review. The advantages and disadvantages of the various assays, including tissue culture assay, enzyme immunoassay, and latex agglutination, currently used in the clinical diagnosis of the disease also are discussed. PMID:3144429

  4. Enzyme-linked immunosorbent assay for Clostridium difficile toxin A.

    PubMed Central

    Lyerly, D M; Sullivan, N M; Wilkins, T D

    1983-01-01

    Antibodies against Clostridium difficile toxin A were purified by affinity chromatography from antiserum prepared against crude C. difficile toxin preparations. The affinity-purified antibody preparation was free of detectable amounts of antibodies to other C. difficile antigens, as demonstrated by crossed immunoelectrophoresis, and specifically neutralized the cytotoxicity of toxin A. An indirect enzyme-linked immunosorbent assay (ELISA) was subsequently developed using the antibody preparation for the specific detection of toxin A. The ELISA, which could detect 1 ng (5 ng/ml) of toxin A, was used to quantitate the toxin in the culture supernatant fluids of strains of C. difficile. The ELISA values for toxin A closely correlated with the toxin A and B cytotoxic titers of the supernatant fluids. In addition, toxin A was detected by ELISA in human fecal specimens from persons with antibiotic-associated colitis, demonstrating that this toxin is produced during C. difficile colitis. Images PMID:6338036

  5. New insights into the functions of anthrax toxin.

    PubMed

    Banks, David J; Ward, Sabrina C; Bradley, Kenneth A

    2006-01-01

    Anthrax is the disease caused by the Gram-positive bacterium Bacillus anthracis. Two toxins secreted by B. anthracis - lethal toxin (LT) and oedema toxin (OT) - contribute significantly to virulence. Although these toxins have been studied for half a century, recent evidence indicates that LT and OT have several roles during infection not previously ascribed to them. Research on toxin-induced effects other than cytolysis of target cells has revealed that LT and OT influence cell types previously thought to be insensitive to toxin. Multiple host factors that confer sensitivity to anthrax toxin have been identified recently, and evidence indicates that the toxins probably contribute to colonisation and invasion of the host. Additionally, the toxins are now known to cause a wide spectrum of tissue and organ pathophysiologies associated with anthrax. Taken together, these new findings indicate that anthrax-toxin-associated pathogenesis is much more complex than has been traditionally recognised. PMID:16608555

  6. Paradichlorobenzene (toxin)-induced leucoencephalopathy

    PubMed Central

    Buckman, Francis

    2013-01-01

    A 40-year-old woman with a history of polysubstance abuse, hypertension, depression and anxiety with panic attacks admitted to the emergency room at the request of her primary physician owing to progressive decline in her mental status associated with anorexia and generalised pruritic skin rashes. Initial outpatient workup and that during two previous hospital admissions including thyroid function and syphilis tests, urine toxicology screen and brain imaging studies were unremarkable. Repeat MRI of the brain during her third hospital admission showed diffuse periventricular and white matter disease. This prompted further questioning of family members which revealed chronic ingestion of mothballs and toilet cakes containing paradichlorobenzene in the patient leading to toxin-induced leucoencephalopathy consistent with her neurological symptoms of altered mental status, ataxic gait, cogwheel rigidity in the arms and characteristic skin rashes. Subsequently, a feeding tube was placed to address her worsening nutritional status and she was discharged home in a stable state. PMID:23608871

  7. The Stable and Radio- Carbon Isotopic Content of Labile and Refractory Carbon in Atmospheric Particulate Matter

    NASA Astrophysics Data System (ADS)

    McNichol, A. P.; Rosenheim, B. E.; Gerlach, D. S.; Hayes, J. M.

    2006-12-01

    Studies of the isotopic content of atmospheric particulate matter are hampered by difficulties in chemically defining the pools of carbon and analytically isolating the different pools. We are conducting studies on reference materials and atmospheric aerosol samples to develop a method to measure stable and radio- carbon isotopes on the labile and refractory carbon. We are using a flow-through combustion system that allows us to combust, collect and measure the isotopic content of the gases produced at all stages of heating/oxidizing. We compare our results to those measured using a chemothermal oxidation method (CTO) (Gustafsson et al., 2001). In this method, refractory carbon is defined as the material remaining after pre- combusting a sample at 375°C in the presence of oxygen for 24 hours. The reference materials are diesel soot, apple leaves and a hybrid of the two (DiesApple), all from NIST. These provide carbon with two well-defined fractions -- the soot provides refractory carbon that is radiocarbon dead and the apple leaves provide organic carbon that is radiocarbon modern. Radiocarbon results from DiesApple indicate that the "refractory" carbon defined by the CTO method is actually a mixture of old and modern carbon that contains over 25% modern carbon. This suggests that charred material formed from the apples leaves during the pre-combustion step is contributing to the fraction we identify as refractory carbon. We are studying this by analyzing the individual materials and the mixture using our flow-through system. First results with this system indicate that the refractory fraction trapped from the DiesApple contains much less modern carbon than the CTO method, less than 7%. We will present detailed concentration and isotopic results of the generation of carbon dioxide during programmed combustion of each of the reference materials. We studied the radiocarbon content of both the total carbon (TC) and refractory carbon in the fine particulate matter (PM2.5) collected on quartz fiber filters as part of the Southeastern Aerosol Research and Characterization (SEARCH) program. The five samples were collected at two sites (Birmingham, AL and Atlanta, GA) with very different sources of atmospheric particulate matter. In all instances, the refractory carbon contained significantly less radiocarbon than the TC suggesting, not unexpectedly, a source of particulate carbon from the combustion of fossil material. We will present results from the analysis of the same filters in the flow-through system. The implication of our results for the use of radiocarbon in the quantitative apportionment of atmospheric particulate matter sources will be discussed. Gustafsson O., T. Bucheli, Z. Kukulska, M. Andersson, C. Largeau, J-N. Rouzaud, C. Reddy and T. Eglinton (2001) Evaluation of a protocol for the quantification of black carbon in sediments. GBD 15, 881-890.

  8. Botulism Due to Clostridium baratii Type F Toxin

    Microsoft Academic Search

    Sydney M. Harvey; Joan Sturgeon; David E. Dassey

    2002-01-01

    Botulism results from consumption of preformed toxin or in vivo toxin elaboration in wounds or intestine. Of U.S. food-borne botulism cases since 1950, the majority were due to toxin A, but a significant number of suspect cases were never confirmed by culture or toxin detection. We report here a possible case of food-borne botulism attributed to toxin F production by

  9. New players in the toxin field: polymorphic toxin systems in bacteria.

    PubMed

    Jamet, Anne; Nassif, Xavier

    2015-01-01

    Bacteria have evolved numerous strategies to increase their competitiveness and fight against each other. Indeed, a large arsenal of antibacterial weapons is available in order to inhibit the proliferation of competitor cells. Polymorphic toxin systems (PTS), recently identified by bioinformatics in all major bacterial lineages, correspond to such a system primarily involved in conflict between related bacterial strains. They are typically composed of a secreted multidomain toxin, a protective immunity protein, and multiple cassettes encoding alternative toxic domains. The C-terminal domains of polymorphic toxins carry the toxic activity, whereas the N-terminal domains are related to the trafficking mode. In silico analysis of PTS identified over 150 distinct toxin domains, including putative nuclease, deaminase, or peptidase domains. Immunity genes found immediately downstream of the toxin genes encode small proteins that protect bacteria against their own toxins or against toxins secreted by neighboring cells. PTS encompass well-known colicins and pyocins, contact-dependent growth inhibition systems which include CdiA and Rhs toxins and some effectors of type VI secretion systems. We have recently characterized the MafB toxins, a new family of PTS deployed by pathogenic Neisseria spp. Many other putative PTS have been identified by in silico predictions but have yet to be characterized experimentally. However, the high number of these systems suggests that PTS have a fundamental role in bacterial biology that is likely to extend beyond interbacterial competition. PMID:25944858

  10. New Players in the Toxin Field: Polymorphic Toxin Systems in Bacteria

    PubMed Central

    Nassif, Xavier

    2015-01-01

    ABSTRACT Bacteria have evolved numerous strategies to increase their competitiveness and fight against each other. Indeed, a large arsenal of antibacterial weapons is available in order to inhibit the proliferation of competitor cells. Polymorphic toxin systems (PTS), recently identified by bioinformatics in all major bacterial lineages, correspond to such a system primarily involved in conflict between related bacterial strains. They are typically composed of a secreted multidomain toxin, a protective immunity protein, and multiple cassettes encoding alternative toxic domains. The C-terminal domains of polymorphic toxins carry the toxic activity, whereas the N-terminal domains are related to the trafficking mode. In silico analysis of PTS identified over 150 distinct toxin domains, including putative nuclease, deaminase, or peptidase domains. Immunity genes found immediately downstream of the toxin genes encode small proteins that protect bacteria against their own toxins or against toxins secreted by neighboring cells. PTS encompass well-known colicins and pyocins, contact-dependent growth inhibition systems which include CdiA and Rhs toxins and some effectors of type VI secretion systems. We have recently characterized the MafB toxins, a new family of PTS deployed by pathogenic Neisseria spp. Many other putative PTS have been identified by in silico predictions but have yet to be characterized experimentally. However, the high number of these systems suggests that PTS have a fundamental role in bacterial biology that is likely to extend beyond interbacterial competition. PMID:25944858

  11. Contributions to the bioassay of Gymnodinium breve toxin(s) with mosquito fish (Gambusia affinis

    E-print Network

    Russell, Melvin Curtis

    1972-01-01

    OONTRISGIIONS TO THE SIOASSAY OF~GodI ' S TOXIN(S) 1VITH MOSQUITO FISH (Gambusia affinis) A Thesis by MELVIN CURTIS RUSSELL Submitted to the Graduate College of Texas A& M University in partial fulfillment of the requirement for the degree... of MASTER OF SCIENCE August 1372 Major Subject; Biology CONTRIBUTIONS TO THE BIORSSRY OF ~Gdr ' B * TOXIN(S) WITH MOSQUITO FISH (Gambusia affinis) A Thesis by MELVIN 'CURTIS RUSSELL Approved as to style and content by: (Chainna f Committee (Head...

  12. The interactions of human neutrophils with shiga toxins and related plant toxins: danger or safety?

    PubMed

    Brigotti, Maurizio

    2012-03-01

    Shiga toxins and ricin are well characterized similar toxins belonging to quite different biological kingdoms. Plant and bacteria have evolved the ability to produce these powerful toxins in parallel, while humans have evolved a defense system that recognizes molecular patterns common to foreign molecules through specific receptors expressed on the surface of the main actors of innate immunity, namely monocytes and neutrophils. The interactions between these toxins and neutrophils have been widely described and have stimulated intense debate. This paper is aimed at reviewing the topic, focusing particularly on implications for the pathogenesis and diagnosis of hemolytic uremic syndrome. PMID:22741061

  13. Dysregulation of hepatic iron with aging: implications for heat stress-induced oxidative liver injury.

    PubMed

    Bloomer, Steven A; Brown, Kyle E; Buettner, Garry R; Kregel, Kevin C

    2008-04-01

    Environmental heat stress is associated with an age-related increase in hepatic oxidative damage and an exaggerated state of oxidative stress. The purpose of this investigation was to evaluate the regulation of hepatic iron after heat stress. A secondary aim was to determine a potential role for iron in heat stress-induced liver injury. Hyperthermia-induced alterations in hepatic iron were evaluated in young (6 mo) and old (24 mo) Fischer 344 rats by exposing them to a two-heat stress protocol. Livers were harvested at several time points after the second heating and assayed for labile and nonheme iron. In the control condition, there was no difference in labile iron between age groups. Both labile iron and storage iron were not altered by hyperthermia in young rats, but both were increased immediately after heating in old rats. To evaluate a role for iron in liver injury, hepatic iron content was manipulated in young and old rats, and then both groups were exposed to heat stress. Iron administration to young rats significantly increased hepatic iron content and ferritin but did not affect markers of lipid peroxidation under control conditions or after heat stress. In old rats, iron chelation with deferoxamine prevented the increase in nonheme iron, labile iron, ferritin, and lipid peroxidation after heat stress. These results suggest that iron may play a role in hepatic injury after hyperthermia. Thus, dysregulation of iron may contribute to the gradual decline in cellular and physiological function that occurs with aging. PMID:18272664

  14. Investigations of Heat Shock Protein Expression in the Swordtail Fishes Xiphophorus birchmanni and X. malinche 

    E-print Network

    Meaders, Ashley M.

    2011-08-04

    In many species, animals must endure environmental stressors such as exposure to heat, toxins, and ultraviolet radiation. To protect cells against such stressors, animals employ an evolutionarily ancient mechanism: the heat shock response. During a...

  15. Stool Test: C. Difficile Toxin (For Parents)

    MedlinePLUS

    ... to Expect When the sample arrives at the laboratory, a technician tests the stool for C. difficile toxins by ... purposes only. For specific medical advice, diagnoses, and treatment, consult your doctor. © 1995- ...

  16. INVESTIGATOIN OF CYANOBACTERIA TOXINS IN WATER

    EPA Science Inventory

    Introduction: Approximately 80 alkaloid and cyclic peptide toxins produced by various freshwater and marine cyanobacteria (blue-green algae) have been identified and their structures determined. The U. S. Environmental Protection Agency has identified two neurotoxin alkalo...

  17. Hemolytic anemia caused by chemicals and toxins

    MedlinePLUS

    Anemia - hemolytic - caused by chemicals or toxins ... Possible substances that can cause hemolytic anemia include: Anti-malaria drugs (quinine compounds) Arsenic Dapsone Intravenous water infusion (not half-normal saline or normal saline) Metals (chromium/chromates, ...

  18. Precursor in cotranslational secretion of diphtheria toxin.

    PubMed Central

    Smith, W P; Tai, P C; Murphy, J R; Davis, B D

    1980-01-01

    By extracellular labeling of peptides of intact Corynebacterium diphtheriae, followed by fractionation of the cells and chain completion by isolated polysomes, it is shown that diphtheria toxin is formed and secreted cotranslationally by membrane-bound polysomes; free polysomes from none. Moreover, when the chains on these polysomes were completed in vitro, in the absence of membrane they were found to include not only diphtheria toxin of a molecular weight of 62,000, but also a larger precursor of a molecular weight of 68,000. The precursor was identified by several properties: immune precipitation; conversion into toxin fragments A and B; adenosine diphosphate ribosyl-transferase activity after activation with trypsin; and cleavage to 62,000 daltons by membrane enzymes. The precursor yields an N-terminal A fragment with a broadened molecular weight distribution, compared with that from authentic toxin, thus supporting the expectation that the extra segment of the precursor is N-terminal. PMID:6243620

  19. How Parkinsonian Toxins Dysregulate the Autophagy Machinery

    PubMed Central

    Dagda, Ruben K.; Das Banerjee, Tania; Janda, Elzbieta

    2013-01-01

    Since their discovery, Parkinsonian toxins (6-hydroxydopamine, MPP+, paraquat, and rotenone) have been widely employed as in vivo and in vitro chemical models of Parkinson’s disease (PD). Alterations in mitochondrial homeostasis, protein quality control pathways, and more recently, autophagy/mitophagy have been implicated in neurotoxin models of PD. Here, we highlight the molecular mechanisms by which different PD toxins dysregulate autophagy/mitophagy and how alterations of these pathways play beneficial or detrimental roles in dopamine neurons. The convergent and divergent effects of PD toxins on mitochondrial function and autophagy/mitophagy are also discussed in this review. Furthermore, we propose new diagnostic tools and discuss how pharmacological modulators of autophagy/mitophagy can be developed as disease-modifying treatments for PD. Finally, we discuss the critical need to identify endogenous and synthetic forms of PD toxins and develop efficient health preventive programs to mitigate the risk of developing PD. PMID:24217228

  20. Nanoanalysis of the arthropod neuro-toxins

    PubMed Central

    Nakajima, Terumi

    2006-01-01

    Many kinds of venomous principles modulate physiological responses of mammalian signal transduction systems, on which they act selectively as enhancers, inhibitors or some other kind of effectors. These toxins become useful tools for physiological research. We have employed and characterized paralyzing toxins from the venom of spiders, insects and scorpions with a limited supply. We have developed rapid and sensitive mass spectrometric technology and applied for the identification of these toxins. Venom profiles are screened by MALDI-TOF fingerprinting analysis prior to purification of venomous components, then marked target toxins of small molecular mass (1000–5000) are characterized directly by means of mass spectrometric techniques such as Frit-FAB MS/MS, CID/PSD-TOF MS, Capil.-HPLC/Q-TOF MS/MS etc. PMID:25792792

  1. The roles of anthrax toxin in pathogenesis.

    PubMed

    Moayeri, Mahtab; Leppla, Stephen H

    2004-02-01

    Anthrax lethal toxin is a multi-functional virulence factor that has evolved to target multiple host functions to allow for optimal establishment of Bacillus anthracis infection. The toxin appears to play a role in all stages of infection, from germination to the induction of vascular collapse leading to host death. Early in infection, at sublethal doses, it acts to suppress immune cell and cytokine responses, thereby promoting bacterial outgrowth. Later in the disease, lethal levels of toxin induce the cytokine-independent shock-like death associated with anthrax. The understanding of the molecular events induced by anthrax toxin in different target cells at each stage of infection will aid in deciphering the pathogenesis of this bacterium and developing therapies. PMID:15036135

  2. ADP-ribosylation by cholera toxin: functional analysis of a cellular system that stimulates the enzymic activity of cholera toxin fragment A/sub 1/

    SciTech Connect

    Gill, D.M.; Coburn, J.

    1987-10-06

    The authors have clarified relationships between cholera toxin, cholera toxin substrates, a membrane protein S that is required for toxin activity, and a soluble protein CF that is needed for the function of S. The toxin has little intrinsic ability to catalyze ADP-ribosylations unless it encounters the active form of the S protein, which is S liganded to GTP or to a GTP analogue. In the presence of CF, S x GTP forms readily, though reversibly, but a more permanent active species, S-guanosine 5'-O-(3-thiotriphosphate) (S x GTP..gamma..S), forms over a period of 10-15 min at 37/sup 0/C. Both guanosine 5'-O-(2-thiodiphosphate) and GTP block this quasi-permanent activation. Some S x GTP..gamma..S forms in membranes that are exposed to CF alone and then to GTP..gamma..S, with a wash in between, and it is possible that CF facilitates a G nucleotide exchange. S x GTP..gamma..S dissolved by nonionic detergents persists in solution and can be used to support the ADP-ribosylation of nucleotide-free substrates. In this circumstance, added guanyl nucleotides have no further effect. This active form of S is unstable, especially when heated, but the thermal inactivation above 45/sup 0/C is decreased by GTP..gamma..S. Active S is required equally for the ADP-ribosylation of all of cholera toxin's protein substrates, regardless of whether they bind GTP or not. They suggest that active S interacts directly with the enzymic A/sub 1/ fragments of cholera toxin and not with any toxin substrate. The activation and activity of S are independent of the state, or even the presence, of adenylate cyclase and seem to be involved with the cyclase system only via cholera toxin. S is apparently not related by function to certain other GTP binding proteins, including p21/sup ras/, and appears to be a new GTP binding protein whose physiologic role remains to be identified.

  3. Biodegradation of the Polyketide Toxin Cercosporin

    Microsoft Academic Search

    Thomas K. Mitchell; William Scott Chilton; Margaret E. Daub

    2002-01-01

    Cercosporin is a non-host-specific polyketide toxin produced by many species of plant pathogens belonging to the genus Cercospora. This red-pigmented, light-activated toxin is an important pathogenicity determinant for Cercospora species. In this study, we screened 244 bacterial isolates representing 12 different genera for the ability to degrade cercosporin. Cercosporin degradation was determined by screening for the presence of cleared zones

  4. Bacillus cereus and its food poisoning toxins

    Microsoft Academic Search

    Per Einar Granum; Terje Lund

    1997-01-01

    Bacillus cereus is becoming one of the more important causes of food poisoning in the industrialised world. It produces one emetic toxin and three different enterotoxins. The emetic toxin is a ring-shaped structure of three repeats of four amino and\\/or oxy acids: [d-O-Leu-d-Ala-l-O-Val-l-Val]3. This ring structure has a molecular mass of 1.2 kDa, and is chemically closely related to the

  5. Sea Anemone Toxins Affecting Potassium Channels

    NASA Astrophysics Data System (ADS)

    Diochot, Sylvie; Lazdunski, Michel

    The great diversity of K+ channels and their wide distribution in many tissues are associated with important functions in cardiac and neuronal excitability that are now better understood thanks to the discovery of animal toxins. During the past few decades, sea anemones have provided a variety of toxins acting on voltage-sensitive sodium and, more recently, potassium channels. Currently there are three major structural groups of sea anemone K+ channel (SAK) toxins that have been characterized. Radioligand binding and electrophysiological experiments revealed that each group contains peptides displaying selective activities for different subfamilies of K+ channels. Short (35-37 amino acids) peptides in the group I display pore blocking effects on Kv1 channels. Molecular interactions of SAK-I toxins, important for activity and binding on Kv1 channels, implicate a spot of three conserved amino acid residues (Ser, Lys, Tyr) surrounded by other less conserved residues. Long (58-59 amino acids) SAK-II peptides display both enzymatic and K+ channel inhibitory activities. Medium size (42-43 amino acid) SAK-III peptides are gating modifiers which interact either with cardiac HERG or Kv3 channels by altering their voltage-dependent properties. SAK-III toxins bind to the S3C region in the outer vestibule of Kv channels. Sea anemones have proven to be a rich source of pharmacological tools, and some of the SAK toxins are now useful drugs for the diagnosis and treatment of autoimmune diseases.

  6. Interactions between recalcitrant and labile organic carbon in streams - Can stream biofilms mediate a priming effect?

    NASA Astrophysics Data System (ADS)

    Bengtsson, M. M.; Wagner, K.; Herberg, E. R.; Burns, N. R.; Wanek, W.; Battin, T. J.

    2012-04-01

    Inland waters - such as streams, rivers and lakes - are increasingly recognized as important components in the global carbon cycle. Dissolved organic carbon (DOC) in these systems is diverse in structure, origin and reactivity, and a fraction of it is regarded as recalcitrant to microbial degradation. In soils, degradation of recalcitrant carbon is often controlled by the availability of labile carbon sources. This is linked to the priming effect (PE). Mounting evidence suggests that PE is also important in aquatic ecosystems but there are so far very few studies addressing this topic. Biofilms are vital components of aquatic ecosystems. In stream biofilms, heterotrophic bacteria and algae coexist in close proximity, exposing the bacteria to both recalcitrant DOC of terrestrial origin and labile organic carbon from the algae. We hypothesize that this makes stream biofilms hotspots for PE. We used plug-flow bioreactors inoculated with natural stream biofilm bacterial communities to test the potential of a priming effect in aquatic ecosystems. The bioreactors were amended with an isotope-labeled plant extract serving as a model of recalcitrant DOC in streams. Labile carbon sources, in the form of glucose and an algal extract were added to induce PE. Nitrate and phosphate were also added to assess the role of these inorganic nutrients on carbon uptake. Microbial uptake of the different carbon sources was monitored by measuring the concentrations and isotopic ratios of respired CO2, biomass and DOC. Our results suggest that the priming effect plays a role in stream carbon cycling and that it is potentially an important process in other aquatic ecosystems.

  7. DOM composition and lability during the Arctic spring freshet on the River Kolyma, Northeast Siberia

    NASA Astrophysics Data System (ADS)

    Mann, P. J.; Davydova, A. I.; Zimov, N.; Bulygina, E. B.; Davydov, S.; Russell-Roy, L.; Zimov, S. A.; Holmes, R. M.

    2010-12-01

    The concentration, composition, age and lability of dissolved organic matter (DOM) exported by Arctic Rivers is known to vary significantly across the hydrograph, affecting the biogeochemical cycling of carbon within high latitude systems. Despite the fact that the majority of the dissolved organic carbon (DOC) flux occurs during the spring freshet, surprisingly little is known about concurrent changes in DOM composition and how this may affect DOC removal processes. In this study, we collected a range of samples throughout the 2010 spring freshet in the Kolyma River and its nearby tributaries, Northeast Siberia. DOM quantity and quality was measured using absorbance and fluorescence spectrophotometry alongside bulk carbon (DOC) and nitrogen (TDN) measurements. Parallel factor analysis (PARAFAC) was employed to decompose fluorescence excitation-emission matrices (EEMs) into distinct fractions. In conjunction with DOM characterization, we investigated the photochemical and bacterial lability of the DOC pool using natural incubation experiments. Kolyma river DOC concentrations ranged from 0.6 mgL-1 under-ice to 14.2 mgL-1 at the peak of the spring flush. Up to 20% DOC loss was observed during 28 d-1 bacterial incubations and 13% loss during 4 d-1 natural sunlight incubations respectively. These percentage losses were greatest in association with maximum riverine DOC concentrations. Furthermore, prior sunlight exposure increased DOM availability for biological remineralization suggesting synergistic pathways in DOC degradation. Absorbance spectral slopes, SUVA254 and PARAFAC modeling results confirm significant changes in DOM composition during the flush and provide useful proxies for DOC lability. With predicted future changes in land-to-ocean carbon fluxes, understanding the link between DOM compositional changes and DOC photo and biolability has clear implications for the overall fate and export of carbon in high-latitude systems.

  8. Production by Clostridium spiroforme of an iotalike toxin that possesses mono(ADP-ribosyl)transferase activity: identification of a novel class of ADP-ribosyltransferases.

    PubMed Central

    Simpson, L L; Stiles, B G; Zepeda, H; Wilkins, T D

    1989-01-01

    Clostridium spiroforme iotalike toxin produced time- and concentration-dependent incorporation of ADP-ribose into homo-poly-L-arginine. Polyasparagine, polyglutamic acid, polylysine, and agmatine were poor substrates. Enzyme activity was associated with the light-chain polypeptide of the toxin. The heavy chain did not possess ADP-ribosyltransferase activity, nor did it enhance or inhibit activity of the light chain. In broken-cell assays, the toxin acted mainly on G-actin, rather than F-actin. A single ADP-ribose group was transferred to each substrate molecule (G-actin). The enzyme was heat sensitive, had a pH optimum in the range of 7 to 8, was inhibited by high concentrations of nicotinamide, and was reversibly denatured by urea and guanidine. Physiological levels of nucleotides (AMP, ADP, ATP, and ADP-ribose) and cations (Na+, K+, Ca2+, and Mg2+) were not very active as enzyme inhibitors. The toxin was structurally and functionally similar to Clostridium botulinum type C2 toxin and Clostridium perfringens iota toxin. When combined with previous findings, the data suggest that a new class of mono(ADP-ribosyl)ating toxins has been found and that these agents belong to a related and possibly homologous series of binary toxins. Images PMID:2521214

  9. Single Plasmonic Nanoparticle Tracking Studies of Solid Supported Bilayers with Ganglioside Lipids

    E-print Network

    Mohseni, Hooman

    in the plasma membranes of mammalian cells, GM1 is a receptor for both cholera toxin and Escherichia coli heat-labile enter- otoxin.11,12 The binding of cholera toxin involves all five B subunits of the protein binding GM1 (the Kd value is smaller) with an increase in ligand concentration,16 the cholera toxin-GM1 system

  10. Organic chemistry of basal ice - presence of labile, low molecular weight compounds available for microbial metabolism

    NASA Astrophysics Data System (ADS)

    Lis, Grzegorz P.; Wadham, Jemma L.; Lawson, Emily; Stibal, Marek; Telling, Jon

    2010-05-01

    Recent studies show that subglacial environments previously thought to be devoid of life contain a host of active microbial organisms. Presence of liquid water due to overburden pressure, the release of nutrients from chemical erosion of bedrock, and the potential carbon sources in overridden sediments facilitate life in this extreme environment. However, little is still known of concentrations and diversity of labile organic compounds essential for sustaining microbial metabolism in subglacial environments. Three subglacial ecosystems that considerably differ in range and amount of available organic compounds were selected for this study 1-Engabreen, northern Norway, overlying high-grade metamorphic rocks with low organic carbon content; 2-Finsterwalderbreen, Svalbard, overriding ancient black shales with a relatively high carbon content yet recalcitrant to microbiological consumption; and 3-Russell Glacier in western Greenland with recently overridden quaternary organic rich paleosols. Basal and pressure ridge ice samples were collected and subsequently analysed for low molecular weight organic compounds, with the emphasis on volatile fatty acids, carbohydrates and amino acids. The highest concentration of labile organic compounds in Greenland basal ice suggest that recently overridden paleosols have the greatest potential for sustaining microbial populations present within and underneath basal ice. The high concentration of "ancient" organic carbon in basal ice from Finsterwalderbreen, Svalbard, doesn't correlate with the presence of labile organic compounds. This indicates the inability of microbes to digest recalcitrant kerogen carbon in cold temperatures. In all three investigated environments, concentrations of labile organic compounds are elevated in basal ice with a high debris content. Until recently, most models of the global carbon cycle tend to neglect the pool of subglacial organic carbon as little is known about the range and concentrations of organic compounds as well as the composition of microbial communities and their ability to degrade and metabolize organic carbon at low temperatures. Recently overridden paleosols in western Greenland may serve as a biogeochemical model for vast pool of organic carbon from areas of boreal forest and tundra overridden during the Quaternary glacial cycles.

  11. Exposure to anthrax toxin alters human leucocyte expression of anthrax toxin receptor 1

    PubMed Central

    Ingram, R J; Harris, A; Ascough, S; Metan, G; Doganay, M; Ballie, L; Williamson, E D; Dyson, H; Robinson, J H; Sriskandan, S; Altmann, D M

    2013-01-01

    Anthrax is a toxin-mediated disease, the lethal effects of which are initiated by the binding of protective antigen (PA) with one of three reported cell surface toxin receptors (ANTXR). Receptor binding has been shown to influence host susceptibility to the toxins. Despite this crucial role for ANTXR in the outcome of disease, and the reported immunomodulatory consequence of the anthrax toxins during infection, little is known about ANTXR expression on human leucocytes. We characterized the expression levels of ANTXR1 (TEM8) on human leucocytes using flow cytometry. In order to assess the effect of prior toxin exposure on ANTXR1 expression levels, leucocytes from individuals with no known exposure, those exposed to toxin through vaccination and convalescent individuals were analysed. Donors could be defined as either ‘low’ or ‘high’ expressers based on the percentage of ANTXR1-positive monocytes detected. Previous exposure to toxins appears to modulate ANTXR1 expression, exposure through active infection being associated with lower receptor expression. A significant correlation between low receptor expression and high anthrax toxin-specific interferon (IFN)-? responses was observed in previously infected individuals. We propose that there is an attenuation of ANTXR1 expression post-infection which may be a protective mechanism that has evolved to prevent reinfection. PMID:23607659

  12. Synthesis and biology of cyclic imine toxins, an emerging class of potent, globally distributed marine toxins.

    PubMed

    Stivala, Craig E; Benoit, Evelyne; Aráoz, Rómulo; Servent, Denis; Novikov, Alexei; Molgó, Jordi; Zakarian, Armen

    2015-02-26

    Covering: up to August 2014From a small group of exotic compounds isolated only two decades ago, Cyclic Imine (CI) toxins have become a major class of marine toxins with global distribution. Their distinct chemical structure, biological mechanism of action, and intricate chemistry ensures that CI toxins will continue to be the subject of fascinating fundamental studies in the broad fields of chemistry, chemical biology, and toxicology. The worldwide occurrence of potent CI toxins in marine environments, their accumulation in shellfish, and chemical stability are important considerations in assessing risk factors for human health. This review article aims to provide an account of chemistry, biology, and toxicology of CI toxins from their discovery to the present day. PMID:25338021

  13. Shiga Toxin (Stx) Classification, Structure, and Function

    PubMed Central

    Melton-Celsa, Angela R.

    2014-01-01

    Shiga toxin (Stx) is one of the most potent bacterial toxins known. Stx is found in Shigella dysenteriae 1 and in some serogroups of Escherichia coli (called Stx1 in E. coli). In addition to or instead of Stx1, some E. coli strains produce a second type of Stx, Stx2, that has the same mode of action as Stx/Stx1 but that is antigenically distinct. Because subtypes of each toxin have been identified, the prototype toxin for each group is now designated Stx1a or Stx2a. The Stxs consist of two major subunits, an A subunit that joins noncovalently to a pentamer of five identical B subunits. The A subunit of the toxin injures the eukaryotic ribosome, and halts protein synthesis in target cells. The function of the B pentamer is to bind to the cellular receptor, globotriaosylceramide, Gb3, found primarily on endothelial cells. The Stxs traffic in a retrograde manner within the cell, such that the A subunit of the toxin reaches the cytosol only after the toxin moves from the endosome to the Golgi and then to the endoplasmic reticulum. In humans infected with Stx-producing E. coli (STEC), the most serious manifestation of the disease, the hemolytic uremic syndrome or HUS, is more often associated with strains that produce Stx2a rather than Stx1a, and that relative toxicity is replicated in mice and baboons. Stx1a and Stx2a also exhibit differences in cytotoxicity to various cell types, bind dissimilarly to receptor analogs or mimics, induce differential chemokine responses, and have several distinctive structural characteristics. PMID:25530917

  14. Inhibition of Cereulide Toxin Synthesis by Emetic Bacillus cereus via Long-Chain Polyphosphates ?

    PubMed Central

    Frenzel, Elrike; Letzel, Thomas; Scherer, Siegfried; Ehling-Schulz, Monika

    2011-01-01

    Severe intoxications caused by the Bacillus cereus emetic toxin cereulide can hardly be prevented due to the ubiquitous distribution and heat resistance of spores and the extreme thermal and chemical stability of cereulide. It would therefore be desirable to inhibit cereulide synthesis during food manufacturing processes or in prepared foods, which are stored under time-temperature abuse conditions. Toward this end, the impacts of three long-chain polyphosphate (polyP) formulations on growth and cereulide production were examined. The inhibition was dependent on the concentration and the type of the polyP blend, indicating that polyPs and not the orthophosphates were effective. Quantitative PCR (qPCR) monitoring at sublethal concentrations revealed that polyPs reduced the transcription of ces nonribosomal peptide synthetase (NRPS) genes by 3- to 4-fold along with a significantly reduced toxin production level. At lower concentrations, toxin synthesis was decreased, although the growth rate was not affected. These data indicate a differential effect on toxin synthesis independent of growth inhibition. The inhibition of toxin synthesis in food was also observed. Despite the growth of B. cereus, toxin synthesis was reduced by 70 to 100% in two model food systems (reconstituted infant food and oat milk), which were analyzed with HEp-2 cell culture assays and high-performance liquid chromatography (HPLC)/electrospray ionization-time of flight mass spectrometry (ESI-TOF-MS). Accordingly, ces promoter activity was strongly downregulated, as visualized by using a lux-based reporter strain. These data illustrate the potential of polyphosphate formulations to reduce the risk of cereulide synthesis in food and may contribute to targeted hurdle concepts. PMID:21169440

  15. Rhizosphere Environment and Labile Phosphorus Release from Organic Waste-Amended Soils.

    NASA Astrophysics Data System (ADS)

    Dao, Thanh H.

    2015-04-01

    Crop residues and biofertilizers are primary sources of nutrients for organic crop production. However, soils treated with large amounts of nutrient-enriched manure have elevated phosphorus (P) levels in regions of intensive animal agriculture. Surpluses occurred in these amended soils, resulting in large pools of exchangeable inorganic P (Pi) and enzyme-labile organic P (Po) that averaging 30.9 and 68.2 mg kg-1, respectively. Organic acids produced during crop residue decomposition can promote the complexation of counter-ions and decouple and release unbound Pi from metal and alkali metal phosphates. Animal manure and cover crop residues also contain large amounts of soluble organic matter, and likely generate similar ligands. However, a high degree of heterogeneity in P spatial distribution in such amended fields, arising from variances in substrate physical forms ranging from slurries to dried solids, composition, and diverse application methods and equipment. Distinct clusters of Pi and Po were observed, where accumulation of the latter forms was associated with high soil microbial biomass C and reduced phosphomonoesterases' activity. Accurate estimates of plant requirements and lability of soil P pools, and real-time plant and soil P sensing systems are critical considerations to optimally manage manure-derived nutrients in crop production systems. An in situ X-ray fluorescence-based approach to sensing canopy and soil XRFS-P was developed to improve the yield-soil P relationship for optimal nutrient recommendations in addition to allowing in-the-field verification of foliar P status.

  16. Lack of correlation between non-labile iron parameters, total carbonyl and malondialdehyde in major thalassemia.

    PubMed

    Al-Hakeim, Hussein Kadhem; Auda, Furqan Muein; Ali, Basim Muhammed

    2014-11-01

    Thalassemia patients are at high risk of iron-induced toxicity and oxidative stress consequences. The present cross-sectional study is conducted to determine whether or not lipid peroxidation or protein oxidation is correlated with iron parameters in patients with thalassemia major. To prove this hypothesis, malondialdehyde and total carbonyl were correlated with the degree of excess iron concentration in the patients. A total of 118 Arabic Iraqi patients and 30 healthy children were participated in the present study. Results showed a significant increase (p<0.05) in serum total carbonyls, malondialdehyde and the iron indices of patients as compared with the control group. Total iron binding capacity and transferrin concentrations decreased significantly (p<0.05) in patients with thalassemia compared with the control group. The results also showed a lack of a significant correlation between each serum malondialdehyde and total carbonyl with each component of iron status. In conclusion, total carbonyls and malondialdehyde were increased in thalassemia patients indicating the vulnerability of these patients to tissue injury caused by oxidative stress. The formation of total carbonyl and malondialdehyde are independent of excess non-labile iron concentration, indicating that different mechanisms are involved in injury caused by the labile iron and in the formation of oxidation end products. PMID:25411527

  17. Heterotrophic activity and biodegradation of labile and refractory compounds by groundwater and stream microbial populations.

    PubMed Central

    Ladd, T I; Ventullo, R M; Wallis, P M; Costerton, J W

    1982-01-01

    The bacteriology and heterotrophic activity of a stream and of nearby groundwater in Marmot Basin, Alberta, Canada, were studied. Acridine orange direct counts indicated that bacterial populations in the groundwater were greater than in the stream. Bacteria that were isolated from the groundwater were similar to species associated with soils. Utilization of labile dissolved organic material as measured by the heterotrophic potential technique with glutamic acid, phenylalanine, and glycolic acid as substrates was generally greater in the groundwater. In addition, specific activity indices for the populations suggested greater metabolic activity per bacterium in the groundwater. 14C-labeled lignocellulose, preferentially labeled in the lignin fraction by feeding Picea engelmannii [14C]phenylalanine, was mineralized by microorganisms in both the groundwater and the stream, but no more than 4% of the added radioactivity was lost as 14CO2 within 960 h. Up to 20% of [3'-14C]cinnamic acid was mineralized by microorganisms in both environments within 500 h. Both microbial populations appear to influence the levels of labile and recalcitrant dissolved organic material in mountain streams. PMID:7125651

  18. Constraints on Transport and Emplacement Mechanisms of Labile Fractions in Lunar Cold Traps

    NASA Technical Reports Server (NTRS)

    Rickman, D.; Gertsch, L.

    2014-01-01

    Sustaining the scientific exploration of the Solar System will require a significant proportion of the necessary fuels and propellants, as well as other bulk commodities, to be produced from local raw materials [1]. The viability of mineral production depends on the ability to locate and characterize mineable deposits of the necessary feedstocks. This requires, among other things, a workable understanding of the mechanisms by which such deposits form, which is the subject of Economic Geology. Multiple deposition scenarios are possible for labile materials on the Moon. This paper suggests labile fractions moved diffusely through space; deposits may grow richer with depth until low porosity rock; lateral transport is likely to have occurred with the regolith, at least for short distances; crystalline ice may not exist; the constituent phases could be extremely complex. At present we can constrain the sources only mildly; once on the Moon, the transport mechanisms inherently mix and therefore obscure the origins. However, the importance of expanding our understanding of ore-forming processes on the Moon behooves us to make the attempt. Thus begins a time of new inquiry for Economic Geology.

  19. Cu lability and bioavailability in an urban stream during baseflow versus stormflow

    NASA Astrophysics Data System (ADS)

    Vadas, T.; Luan, H.

    2012-12-01

    Urban streams are dynamic systems with many anthropogenic inputs and stressors. Existing contaminant inputs are regulated through total maximum daily loads. Techniques for assessing that load are based on a combination of acute and chronic water quality criteria, biotic ligand models, and physical, chemical and biological assessments. In addition, the apportionment of reduction in load to different sources is based on total mass and not, for example, on bioavailable fraction. Our understanding of the impact of different metal inputs to stream impairment is limited. Free metal ions are understood to play a role in direct cellular uptake, but metal speciation (e.g. free metal, labile metals, or size fractionated) is relevant to more complex stream food webs. As part of an ongoing study, this work examines dissolved and particulate Cu concentrations in the Hockanum River, Vernon, CT situated in a developed watershed. Stream samples were taken during baseflow as well as stormflow upstream and downstream of wastewater treatment plant and stormwater runoff inputs. In addition, diffusive gradient in thin-film (DGT) devices which measure labile metal concentrations and cultured periphyton were used to examine bioavailable fractions. Total and filtered Cu concentrations ranged from about 1.3 to 10.7 ?g/L, and 0.9 to 5.1 ?g/L, respectively. Cu concentrations always increased downstream of the wastewater treatment plant by about 1.1-2 times, and effluent accounted for about 30% of baseflow. Generally, small increases (<10%) in concentration were observed in metals directly downstream of stormwater inlets, likely due to low volumes of runoff contributed from stormwater outfalls during these sampling periods. However, Cu concentrations were elevated (about 2-5 times higher) at all sites downstream from the wastewater treatment plant downstream sampling point, suggesting contributions from sediment resuspension. DGT measured concentrations represented 30 to 70% of dissolved Cu concentrations, and that percentage increased in the days following a storm, suggesting more labile Cu compounds remained in the water column longer. Whereas solution metal concentrations in stormwater influenced reaches did not largely change upstream versus downstream, concentrations of Cu in periphyton cultures increased 2-fold downstream of a stormwater input. This is likely due to differences in discrete sampling locations, but indicates the potential importance of resuspended sediment on enhancing metal bioavailability. These results suggest that legacy sediment contamination is contributing to water column Cu concentrations. Downstream Cu concentrations are elevated compared to near the wastewater treatment plant effluent but are mostly unchanged before and after stormwater inputs. In addition, DGT concentrations indicate a shift in percentage of labile metals, in part distinguished based on size exclusion by the DGT device, following a storm event. As total dissolved Cu concentration decreases, labile Cu increases likely due to settling or size dependent partitioning to the solid phases such as periphyton. Understanding the transport and bioavailability of size dependent Cu compounds in stream water is important to allocating resources to mitigate metal contamination.

  20. [Production and characteristics of monoclonal antibodies to the diphtheria toxin].

    PubMed

    Valiakina, T I; Lakhtina, O E; Komaleva, R L; Simonova, M A; Samokhvalova, L V; Shoshina, N S; Kalinina, N A; Rubina, A Iu; Filippova, M A; Vertiev, Iu V; Grishin, E V

    2009-01-01

    Monoclonal antibodies to the diphtheria toxin were produced without cross reactivity with the thermolabile toxin (LT) from Escherichia coli; ricin; choleraic toxin; the SeA, SeB, SeE, SeI, and SeG toxins of staphylococcus; the lethal factor of the anthrax toxin; and the protective antigen of the anthrax toxin. A pair of antibodies for the quantitative determination of the diphtheria toxin in the sandwich variation of enzyme-linked immunosorbent assay (ELISA) was chosen. The determination limit of the toxin was 0.7 ng/ml in plate and 1.6 ng/ml in microchip ELISA. The presence of a secretion from the nasopharynx lavage did not decrease the sensitivity of the toxin determination by sandwich ELISA. The immunization of mice with the diphtheria toxin and with a conjugate of the diphtheria toxin with polystyrene microspheres demonstrated that the conjugate immunization resulted in the formation of hybridoma clones which produced antibodies only to the epitopes of the A fragment of the diphtheria toxin. The immunization with the native toxin caused the production of hybridoma clones which predominantly produced antibodies to the epitopes of the B fragment. PMID:19915639

  1. A Truncated Diphtheria Toxin Based Recombinant Porcine CTLA-4 Fusion Toxin

    PubMed Central

    Peraino, Jaclyn Stromp; Schenk, Marian; Zhang, Huiping; Li, Guoying; Hermanrud, Christina E.; Neville, David M.; Sachs, David H.; Huang, Christene A.; Duran-Struuck, Raimon; Wang, Zhirui

    2013-01-01

    Targeted cell therapies are possible through the generation of recombinant fusion proteins that combine a toxin, such as diphtheria toxin (DT), with an antibody or other molecule that confers specificity. Upon binding of the fusion protein to the cell of interest, the diphtheria toxin is internalized which results in protein synthesis inhibition and subsequent cell death. We have recently expressed and purified the recombinant soluble porcine CTLA-4 both with and without N-glycosylation in yeast Pichia Pastoris for in vivo use in our preclinical swine model. The glycosylated and non-N-glycosylated versions of this recombinant protein each bind to a porcine CD80 expressing B-cell lymphoma line (LCL13271) with equal affinity (KD = 13 nM). In this study we have linked each of the glycosylated and non-N-glycosylated soluble porcine CTLA-4 proteins to the truncated diphtheria toxin DT390 through genetic engineering yielding three versions of the porcine CTLA-4 fusion toxins: 1) monovalent glycosylated soluble porcine CTLA-4 fusion toxin; 2) monovalent non-N-glycosylated soluble porcine CTLA-4 fusion toxin and 3) bivalent non-N-glycosylated soluble porcine CTLA-4 fusion toxin. Protein synthesis inhibition analysis demonstrated that while all three fusion toxins are capable of inhibiting protein synthesis in vitro, the non-N-glycosylated porcine CTLA-4 isoforms function most efficiently. Binding analysis using flow cytometry of the porcine CTLA-4 fusion toxins to LCL13271 cells also demonstrated that the non-N-glycosylated porcine CTLA-4 isoforms bind to theses cells with higher affinity compared to the glycosylated fusion toxin. The monovalent non-N-glycosylated porcine CTLA-4 fusion toxin was tested in vivo. NSG (NOD/SCID IL-2 receptor ??/?) mice were injected with porcine CD80+ LCL13271 tumor cells. All animals succumbed to tumors and those treated with the monovalent non-N-glycosylated porcine CTLA-4 fusion toxin survived longer based on a symptomatic scoring system compared to the untreated controls. This recombinant protein may therefore provide a novel approach for in vivo depletion of porcine antigen presenting cells (APCs) for studies investigating the induction of transplantation tolerance, autoimmune disease and cancer treatment. PMID:23470981

  2. Effect of heat and thermosonication treatments on peroxidase inactivation kinetics in watercress ( Nasturtium officinale)

    Microsoft Academic Search

    Rui M. S. Cruz; Margarida C. Vieira; Cristina L. M. Silva

    2006-01-01

    The effect of heat and the combined heat\\/ultrasound (thermosonication) treatment on the inactivation kinetics of peroxidase in watercress (Nasturtium officinale) was studied in the temperature range of 40–92.5°C. In the heat blanching processes, the enzyme kinetics showed a first-order biphasic inactivation model. The activation energies and the rates of the reaction at a reference temperature for both the heat-labile and

  3. Anthrax toxin: structures, functions and tumour targeting.

    PubMed

    Liu, Shihui; Schubert, Rebecca L; Bugge, Thomas H; Leppla, Stephen H

    2003-08-01

    Anthrax toxin, the major virulence factor of Bacillus anthracis, consists of three polypeptides: protective antigen (PrAg), lethal factor (LF) and oedema factor (EF). To intoxicate mammalian cells, PrAg binds to its cellular receptors and is subsequently activated via proteolysis, yielding a carboxyl-terminal fragment which coordinately assembles to form heptamers that bind and translocate LF and EF into the cytosol to exert their cytotoxic effects. Substantial progress has been made in recent years towards the characterisation of the structure and function of anthrax toxin, and this has greatly facilitated rational drug design of antianthrax agents. There is also emerging evidence that toxins can be manipulated for cancer therapy. LF can efficiently inactivate several mitogen-activated protein kinase kinases (MAPKKs) via cleavage of their amino-terminal sequences. Consequently, antitumour effects of wild type lethal toxin were observed after treatment of mitogen-activated protein kinase (MAPK)-dependent tumours such as human melanomas. Modification of the toxin's proteolytic activation site limits its cytotoxicity to certain cell types and creates a versatile method of treatment. One approach that has successfully achieved specific tumour targeting is the alteration of the furin cleavage of PrAg so that it is not activated by furin, but, alternatively, by proteases that are highly expressed by tumour tissues, including matrix metalloproteases and urokinase. PMID:12880383

  4. Cyanobacterial Toxin Degrading Bacteria: Who Are They?

    PubMed Central

    Kormas, Konstantinos Ar.; Lymperopoulou, Despoina S.

    2013-01-01

    Cyanobacteria are ubiquitous in nature and are both beneficial and detrimental to humans. Benefits include being food supplements and producing bioactive compounds, like antimicrobial and anticancer substances, while their detrimental effects are evident by toxin production, causing major ecological problems at the ecosystem level. To date, there are several ways to degrade or transform these toxins by chemical methods, while the biodegradation of these compounds is understudied. In this paper, we present a meta-analysis of the currently available 16S rRNA and mlrA (microcystinase) genes diversity of isolates known to degrade cyanobacterial toxins. The available data revealed that these bacteria belong primarily to the Proteobacteria, with several strains from the sphingomonads, and one from each of the Methylobacillus and Paucibacter genera. Other strains belonged to the genera Arthrobacter, Bacillus, and Lactobacillus. By combining the ecological knowledge on the distribution, abundance, and ecophysiology of the bacteria that cooccur with toxic cyanobacterial blooms and newly developed molecular approaches, it is possible not only to discover more strains with cyanobacterial toxin degradation abilities, but also to reveal the genes associated with the degradation of these toxins. PMID:23841072

  5. 42 CFR 73.4 - Overlap select agents and toxins.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...b) Overlap select agents and toxins: Bacillus anthracis *; Bacillus anthracis (Pasteur strain); Brucella abortus...toxin to CDC or APHIS. (i) The seizure of Bacillus anthracis, Burkholderia mallei and Burkholderia...

  6. 42 CFR 73.4 - Overlap select agents and toxins.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...products. (b) Overlap select agents and toxins: Bacillus anthracis Brucella abortus Brucella melitensis Brucella...or toxin to CDC or APHIS. (i) The seizure of Bacillus anthracis, Brucella melitensis, Hendra virus,...

  7. 42 CFR 73.4 - Overlap select agents and toxins.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...b) Overlap select agents and toxins: Bacillus anthracis *; Bacillus anthracis (Pasteur strain); Brucella abortus...toxin to CDC or APHIS. (i) The seizure of Bacillus anthracis, Burkholderia mallei and Burkholderia...

  8. Current clinical applications of botulinum toxin.

    PubMed

    Truong, Daniel D; Stenner, Andrea; Reichel, Gerhard

    2009-01-01

    Botulinum toxin has long been known for its paralytic effects on the human voluntary musculature via inhibition of acetylcholine release at neuromuscular junctions. Its original clinical use for the treatment of strabismus has expanded significantly to include neurological conditions related to muscle hyperactivity and/or spasticity (e.g., dystonia, spasticity, tics, tremor, dysphonia). Recently, botulinum toxin has been shown to impact autonomic disorders by acting at acceptors on glands and smooth muscle, and consequently it has been used in the management of a number of other conditions including hypersecretory disorders, pain syndromes, detrusor sphinchter dyssenergia or overactivity and gastointestinal smooth muscle/sphincter spasm; it may also reduce pain in patients for whom it is used to treat these and other primary conditions. This article will review the pharmacology and formulations of botulinum toxins as well as data from clinical trials demonstrating their efficacy for numerous conditions based on their effects on cholinergic synapses outside the motor nervous system. PMID:19925419

  9. Anthrax toxin and genetic aspects regulating its expression

    Microsoft Academic Search

    Amy E. Tucker; Jimmy D. Ballard

    Anthrax toxin is a unique, tripartite bacterial toxin, capable of causing edema and lethality through binary combinations of protective antigen (PA) with either edema factor (EF) or lethal factor (LF). The toxin-encoding genes (pagA, lef, cya) are maintained on a ~44 kb pathogenicity island (PAI), found on the large plasmid, pXO1. The toxin encoding genes are subject to inducible expression in

  10. ANALYSES OF WOUND EXUDATES FOR CLOSTRIDIAL TOXINS

    PubMed Central

    Noyes, Howard E.; Pritchard, William L.; Brinkley, Floyd B.; Mendelson, Janice A.

    1964-01-01

    Noyes, Howard E. (Walter Reed Army Institute of Research, Washington, D.C.), William L. Pritchard, Floyd B. Brinkley, and Janice A. Mendelson. Analyses of wound exudates for clostridial toxins. J. Bacteriol. 87:623–629. 1964.—Earlier studies indicated that death of goats with traumatic wounds of the hindquarter could be related to the number of clostridia in the wounds, and that toxicity of wound exudates for mice and guinea pigs could be partially neutralized by commercial trivalent gas gangrene antitoxin. This report describes in vitro and in vivo analyses of wound exudates for known clostridial toxins. Wounds were produced by detonation of high-explosive pellets. Wound exudates were obtained by cold saline extraction of both necrotic tissues and gauze sponges used to cover the wounds. Exudates were sterilized by Seitz filtration in the cold. In vitro tests were used to measure alpha-, theta-, and mu-toxins of Clostridium perfringens and the epsilon-toxin of C. novyi. Mouse protection tests, employing commercial typing antisera, were used to analyze exudates for other clostridial toxins. Lethality of wound exudates for mice could be related to (i) the numbers of clostridia present in the wound, (ii) survival time of the goats, and (iii) positive lecithovitellin (LV) tests of the exudates. However, the LV tests could not be neutralized by antitoxin specific for C. perfringens alpha-toxin. Mice were not protected by typing antisera specific for types A, C, or D C. perfringens or C. septicum but were protected by antisera specific for type B C. perfringens and types A and B C. novyi. PMID:14127581

  11. The induction of toxin neutralizing antibodies to Clostridium perfringens types C and D toxins in horses

    E-print Network

    Brooks, Frances Lynn

    1983-01-01

    THE INDUCTION OF TOXIN NEUTRALIZING ANTIBODIES TO CLOSTRIDIUM PERFRINGENS TYPES C AND D TOXINS IN HORSES A Thes1s by FRANCES LYNN BROOKS Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirements... and content by: Russe B. Simpson~~ (Chairman of Committee) (21 ) /'' James E. Grimes (Nember) John M. Bowen (Nember) Ian R. Tizard (Head of Department) December 1983 ABSTRACT The Induction of Toxin Neutraliz1ng Ant1bodies to Clostridium Oeeff ti...

  12. Bacterial Toxins and the Nervous System: Neurotoxins and Multipotential Toxins Interacting with Neuronal Cells

    PubMed Central

    Popoff, Michel R.; Poulain, Bernard

    2010-01-01

    Toxins are potent molecules used by various bacteria to interact with a host organism. Some of them specifically act on neuronal cells (clostridial neurotoxins) leading to characteristics neurological affections. But many other toxins are multifunctional and recognize a wider range of cell types including neuronal cells. Various enterotoxins interact with the enteric nervous system, for example by stimulating afferent neurons or inducing neurotransmitter release from enterochromaffin cells which result either in vomiting, in amplification of the diarrhea, or in intestinal inflammation process. Other toxins can pass the blood brain barrier and directly act on specific neurons. PMID:22069606

  13. The induction of toxin neutralizing antibodies to Clostridium perfringens types C and D toxins in horses 

    E-print Network

    Brooks, Frances Lynn

    1983-01-01

    THE INDUCTION OF TOXIN NEUTRALIZING ANTIBODIES TO CLOSTRIDIUM PERFRINGENS TYPES C AND D TOXINS IN HORSES A Thes1s by FRANCES LYNN BROOKS Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirements... and content by: Russe B. Simpson~~ (Chairman of Committee) (21 ) /'' James E. Grimes (Nember) John M. Bowen (Nember) Ian R. Tizard (Head of Department) December 1983 ABSTRACT The Induction of Toxin Neutraliz1ng Ant1bodies to Clostridium Oeeff ti...

  14. 14C as a tracer of labile organic matter in Antarctic benthic food webs

    NASA Astrophysics Data System (ADS)

    Purinton, Brett L.; DeMaster, David J.; Thomas, Carrie J.; Smith, Craig R.

    2008-11-01

    14C measurements were made on surface plankton, particle-trap material, surface sediment, benthic invertebrate gut contents, and body tissue samples to assess the effectiveness of this radioisotope as a tracer of labile organic carbon in Antarctic benthic food webs. Samples were collected on five cruises to the West Antarctic Peninsula (WAP) shelf between November 1999 and March 2001 as part of the Food for Benthos on the ANtarctic Continental-Shelf (FOODBANCS) Project. The 14C contents of the body tissues from a variety of deposit feeders (-126±13 per mil) were substantially enriched relative to the surface sediment (-234±13 per mil) and statistically similar to the organic matter collected in plankton tows (-135±10 per mil), indicating that recently produced marine plankton are the primary source of nutrition for these deposit feeders on the West Antarctic shelf. Selective ingestion was the primary feeding strategy used by echiuran worms and certain holothurians (i.e. Peniagone vignoni) for incorporating labile organic carbon into their tissues as demonstrated by the large differences (105±13 per mil) between surface sediment and gut content 14C activities. In contrast, digestive and/or assimilatory selection was the predominant strategy used by an irregular urchin ( Amphipneustes lorioli) and several other holothurians ( Protelpidia murrayi, Bathyplotes fuscivinculum and the head-down conveyor belt feeder, Molpadia musculus), as demonstrated by large differences (42±7 per mil) between the 14C activities of their foregut or whole-gut organic contents and their body tissues. Despite large fluctuations in carbon export from the euphotic zone, benthic feeding strategies remained essentially constant over the 15-month sampling period. No seasonal variation was evident in either the 14C abundance of the deposit-feeder body tissues, or in the 14C abundance of their gut contents. The mean 14C abundance in the body tissues of the two sub-surface deposit feeders ( A. lorioli and M. musculus; mean=-136.2±8.5 per mil) was distinct ( p=0.0008) from the mean 14C abundance in the body tissues of the four surface deposit feeders (echiuran worm, P. vignoni, P. murrayi, and B. fusciviculum; -122.6±12.3 per mil). The mean 14C abundance of the gut contents from the sub-surface deposit feeders (-178.0±18.6 per mil) also was significantly depleted ( p=0.0009) relative to that of the surface deposit feeders (-149.5±26.6 per mil). The 14C measurements proved to be a much more sensitive tracer for tracking labile organic carbon during ingestive and assimilatory processes than the stable isotopes of carbon or nitrogen.

  15. Commentary: botulinum toxin in clinical medicine.

    PubMed

    Benedetto, Anthony V

    2003-01-01

    The recent introduction of botulinum toxin (BTX) into clinical medicine has revolutionized the practice of medicine and surgery forever. Who would have ever thought that the world's most deadly of all toxins would be used for therapeutic purposes? The discovery of the beneficial effects of BTX has transformed the lives of many unfortunate individuals who have suffered from a variety of unrelated disorders, which have been virtually impossible to treat. With the help of BTX, these and hopefully many other ailments will be easily managed with a few simple injections. PMID:14759576

  16. Natural Toxins for Use in Pest Management

    PubMed Central

    Duke, Stephen O.; Cantrell, Charles L.; Meepagala, Kumudini M.; Wedge, David E.; Tabanca, Nurhayat; Schrader, Kevin K.

    2010-01-01

    Natural toxins are a source of new chemical classes of pesticides, as well as environmentally and toxicologically safer molecules than many of the currently used pesticides. Furthermore, they often have molecular target sites that are not exploited by currently marketed pesticides. There are highly successful products based on natural compounds in the major pesticide classes. These include the herbicide glufosinate (synthetic phosphinothricin), the spinosad insecticides, and the strobilurin fungicides. These and other examples of currently marketed natural product-based pesticides, as well as natural toxins that show promise as pesticides from our own research are discussed. PMID:22069667

  17. Botulinum toxin type A in pregnancy

    PubMed Central

    Tan, Michael; Kim, Eunji; Koren, Gideon; Bozzo, Pina

    2013-01-01

    Abstract Question My patient received 62 units of botulinum toxin type A (BTX-A) for facial lines. Two weeks later, she found out that she was pregnant. Will this cause any harm to her fetus? Answer Botulinum toxin is not expected to be present in systemic circulation following proper intramuscular or intradermal injection. Moreover, BTX-A, which has a high molecular weight, does not appear to cross the placenta. From the 38 pregnancies reported in the literature, including women who had botulism poisoning during pregnancy, exposure to BTX-A does not appear to increase the risk of adverse outcome in the fetus. PMID:24235190

  18. MICROBIOLOGY: Arresting Features of Bacterial Toxins

    NSDL National Science Digital Library

    Jenifer Coburn (Tufts-New England Medical Center; Division of Rheumatology and Immunology)

    2000-10-13

    Access to the article is free, however registration and sign-in are required: Bacteria produce an arsenal of sophisticated toxins that disrupt the normal processes of the host cell, usually by modifying or inactivating host cell proteins. Now, as Coburn and Leong discuss in their Perspective, members of the cytolethal distending toxin (CDT) family have been identified as enzymes that attack DNA (and not protein) within the host cell (Lara-Tejero and Galán). By attacking DNA, perhaps during chromosomal replication, CDTs cause the host cell to halt in G2 phase of the cell cycle.

  19. Somacional variation and eyespot toxin tolerance in sugarcane

    Microsoft Academic Search

    P. J. Larkin; W. R. Scowcroft

    1983-01-01

    The analysis of sugarcane plants regenerated from culture for their reaction to eyespot (Helminthosporium sacchari) toxin is described. A total of 480 culture-derived plants (somaclones) from cultivar Q101 were characterized. Some of these plants derived from cultures which had been subjected to selection with the eyespot toxin and others were derived without overt selection. Leaves were assayed for their toxin

  20. Receptor-specific requirements for anthrax toxin delivery into cells

    E-print Network

    Sejnowski, Terrence J.

    . The current model of anthrax toxin entry invokes (PA63)7 prepore conversion to a 14-stranded -barrel-containingReceptor-specific requirements for anthrax toxin delivery into cells G. Jonah A. Rainey*, Darran J Contributed by R. John Collier, July 12, 2005 The three proteins that constitute anthrax toxin self

  1. Blue-green algal toxin (microcystin) levels in Minnesota lakes

    Microsoft Academic Search

    Matt Lindon; Steven Heiskary

    2009-01-01

    Increased interest in blue-green algal toxins in recent years has led to increased monitoring to assess occurrence and levels of toxins in Minnesota lakes. Microcystin (MC), a hepatotoxin, is one of the primary toxins studied in Minnesota and elsewhere in North America. The Minnesota Pollution Control Agency has measured MC in numerous lakes across Minnesota as a part of three

  2. Anthrax toxin-induced rupture of artificial lipid bilayer membranes.

    PubMed

    Nablo, Brian J; Panchal, Rekha G; Bavari, Sina; Nguyen, Tam L; Gussio, Rick; Ribot, Wil; Friedlander, Art; Chabot, Donald; Reiner, Joseph E; Robertson, Joseph W F; Balijepalli, Arvind; Halverson, Kelly M; Kasianowicz, John J

    2013-08-14

    We demonstrate experimentally that anthrax toxin complexes rupture artificial lipid bilayer membranes when isolated from the blood of infected animals. When the solution pH is temporally acidified to mimic that process in endosomes, recombinant anthrax toxin forms an irreversibly bound complex, which also destabilizes membranes. The results suggest an alternative mechanism for the translocation of anthrax toxin into the cytoplasm. PMID:23947891

  3. Anthrax toxin-induced rupture of artificial lipid bilayer membranes

    PubMed Central

    Nablo, Brian J.; Panchal, Rekha G.; Bavari, Sina; Nguyen, Tam L.; Gussio, Rick; Ribot, Wil; Friedlander, Art; Chabot, Donald; Reiner, Joseph E.; Robertson, Joseph W. F.; Balijepalli, Arvind; Halverson, Kelly M.; Kasianowicz, John J.

    2013-01-01

    We demonstrate experimentally that anthrax toxin complexes rupture artificial lipid bilayer membranes when isolated from the blood of infected animals. When the solution pH is temporally acidified to mimic that process in endosomes, recombinant anthrax toxin forms an irreversibly bound complex, which also destabilizes membranes. The results suggest an alternative mechanism for the translocation of anthrax toxin into the cytoplasm. PMID:23947891

  4. Expression of Botulinum Toxin Binding Sites in Xenopus Oocytes

    Microsoft Academic Search

    NABIL M. BAKRY; YOICHI KAMATA; LANCE L. SIMPSON

    1997-01-01

    The binding of iodinated botulinum toxin type B to nerve membranes was studied by using rat and mouse preparations. The toxin was examined both in the single-chain and in the proteolytically processed dichain form, and binding sites both in the spinal cord and in various brain regions were assayed. Rat and mouse brains possessed specific binding sites for botulinum toxin

  5. Shiga toxins — from cell biology to biomedical applications

    Microsoft Academic Search

    Winfried Römer; Ludger Johannes

    2009-01-01

    Shiga toxin-producing Escherichia coli is an emergent pathogen that can induce haemolytic uraemic syndrome. The toxin has received considerable attention not only from microbiologists but also in the field of cell biology, where it has become a powerful tool to study intracellular trafficking. In this Review, we summarize the Shiga toxin family members and their structures, receptors, trafficking pathways and

  6. Shiga toxins and their mechanisms of cell entry

    Microsoft Academic Search

    Kirsten Sandvig; Sébastien Wälchli; Silje U. Lauvrak

    The Shiga toxins (Stxs) are related toxins secreted by Shigella dysenteriae, Escherichia coli in addition to other bacteria. They all act by entering cells and inhibiting protein synthesis enzymatically, thereby, killing the cells. Toxicity can also be mediated by induction of apoptosis. Furthermore, the Shiga toxins can in some cells induce secretion of a number of cytokines, some of which

  7. EFFECTS OF MARINE ALGAL TOXINS ON THERMOREGULATION IN MICE.

    EPA Science Inventory

    Hypothermia is often seen in mice and rats exposed acutely to marine algal toxins, but the mechanism of action of these toxins on thermoregulation is not well understood. Our laboratory has assessed the thermoregulatory mechanisms of two marine algal toxins, maitotoxin and brevet...

  8. Application of a chemical leach technique for estimating labile particulate aluminum, iron, and manganese in the Columbia River plume and coastal waters off Oregon and Washington

    Microsoft Academic Search

    Carolyn J. M. Berger; Sherry M. Lippiatt; Michael G. Lawrence; Kenneth W. Bruland

    2008-01-01

    In order to determine the total concentration of bioavailable trace metals in seawater, measurement of both the dissolved and labile particulate fractions is necessary. Comparison of labile particulate metal concentrations from various researchers is limited because of differing definitions of the fraction that is potentially available to phytoplankton on a time frame of generations. A comparison experiment was conducted on

  9. Marine Toxins Targeting Ion Channels

    PubMed Central

    Arias, Hugo R.

    2006-01-01

    This introductory minireview points out the importance of ion channels for cell communication. The basic concepts on the structure and function of ion channels triggered by membrane voltage changes, the so-called voltage-gated ion channels (VGICs), as well as those activated by neurotransmitters, the so-called ligand-gated ion channel (LGICs), are introduced. Among the most important VGIC superfamiles, we can name the voltage-gated Na+ (NaV), Ca2+ (CaV), and K+ (KV) channels. Among the most important LGIC super families, we can include the Cys-loop or nicotinicoid, the glutamate-activated (GluR), and the ATP-activated (P2XnR) receptor superfamilies. Ion channels are transmembrane proteins that allow the passage of different ions in a specific or unspecific manner. For instance, the activation of NaV, CaV, or KV channels opens a pore that is specific for Na+, Ca2+, or K+, respectively. On the other hand, the activation of certain LGICs such as nicotinic acetylcholine receptors, GluRs, and P2XnRs allows the passage of cations (e.g., Na+, K+, and/or Ca2+), whereas the activation of other LGICs such as type A ?-butyric acid and glycine receptors allows the passage of anions (e.g., Cl? and/or HCO3?). In this regard, the activation of NaV and CaV as well as ligand-gated cation channels produce membrane depolarization, which finally leads to stimulatory effects in the cell, whereas the activation of KV as well as ligand-gated anion channels induce membrane hyperpolarization that finally leads to inhibitory effects in the cell. The importance of these ion channel superfamilies is emphasized by considering their physiological functions throughout the body as well as their pathophysiological implicance in several neuronal diseases. In this regard, natural molecules, and especially marine toxins, can be potentially used as modulators (e.g., inhibitors or prolongers) of ion channel functions to treat or to alleviate a specific ion channel-linked disease (e.g., channelopaties).

  10. Clostridium difficile toxin B is more potent than toxin A in damaging human colonic epithelium in vitro.

    PubMed Central

    Riegler, M; Sedivy, R; Pothoulakis, C; Hamilton, G; Zacherl, J; Bischof, G; Cosentini, E; Feil, W; Schiessel, R; LaMont, J T

    1995-01-01

    Toxin A but not toxin B, appears to mediate intestinal damage in animal models of Clostridium difficile enteritis. The purpose of this study was to investigate the electrophysiologic and morphologic effects of purified C. difficile toxins A and B on human colonic mucosa in Ussing chambers. Luminal exposure of tissues to 16-65 nM of toxin A and 0.2-29 nM of toxin B for 5 h caused dose-dependent epithelial damage. Potential difference, short-circuit current and resistance decreased by 76, 58, and 46%, respectively, with 32 nM of toxin A and by 76, 55, and 47%, respectively, with 3 nM of toxin B, when compared with baseline (P < 0.05). 3 nM of toxin A did not cause electrophysiologic changes. Permeability to [3H]mannitol increased 16-fold after exposure to 32 nM of toxin A and to 3 nM of toxin B when compared with controls (P < 0.05). Light and scanning electron microscopy after exposure to either toxin revealed patchy damage and exfoliation of superficial epithelial cells, while crypt epithelium remained intact. Fluorescent microscopy of phalloidin-stained sections showed that both toxins caused disruption and condensation of cellular F-actin. Our results demonstrate that the human colon is approximately 10 times more sensitive to the damaging effects of toxin B than toxin A, suggesting that toxin B may be more important than toxin A in the pathogenesis of C. difficile colitis in man. Images PMID:7738167

  11. The effects of childhood trauma on daily mood lability and comorbid psychopathology in bulimia nervosa.

    PubMed

    Wonderlich, Stephen A; Rosenfeldt, Steven; Crosby, Ross D; Mitchell, James E; Engel, Scott G; Smyth, Joshua; Miltenberger, Raymond

    2007-02-01

    A study of bulimic women examined the relationship between histories of childhood trauma and psychiatric disorders, as well as daily measures of mood and behavior. One hundred twenty-three women with bulimia nervosa were assessed with interviews and completed an Ecological Momentary Assessment (EMA) protocol in which they carried a palmtop computer for 2 weeks. Sexual abuse was associated with a history of mood and anxiety disorders, and emotional abuse with eating disorder psychopathology. In the EMA assessment, sexual abuse was associated with daily purging frequency and self-destructive behavior. Emotional abuse was associated with average daily mood and mood lability. These findings support the idea that child maltreatment may be associated with various aspects of bulimia-related psychopathology. PMID:17345648

  12. A superior drug carrier – aponeocarzinostatin in partially unfolded state fully protects the labile antitumor enediyne

    PubMed Central

    Shanmuganathan, Aranganathan; Kumar, Thallapuranam Krishnaswamy Suresh; Huang, Chiy-Mey; Yu, Chin; Chin, Der-Hang

    2009-01-01

    Background Neocarzinostatin is a potent antitumor drug consisting of an enediyne chromophore and a protein carrier. Methods We characterized an intermediate in the equilibrium unfolding pathway of aponeocarzinostatin, using a variety of biophysical techniques including 1-anilino-8-napthalene sulfonate binding studies, size-exclusion fast protein liquid chromatography, intrinsic tryptophan fluorescence, circular dichroism, and 1H-15N heteronuclear single quantum coherence spectroscopy. Results The partially unfolded protein is in molten globule-like state, in which ~60% and ~20% tertiary and secondary structure is disrupted respectively. Despite lacking a fully coordinated tertiary structure for assembling a functional binding cleft, the protein in molten globule-like state is still able to fully protect the labile chromophore. Titration of chromophore leads the partially denatured apoprotein to fold into its native state. Conclusion These findings bring insight into conserving mechanism of neocarzinostatin under harsh environment, where even the partially denatured apoprotein exhibits protective effect, confirming the superiority of the drug carrier. PMID:19463188

  13. Significance of Isotopically Labile Organic Hydrogen in Thermal Maturation of Organic Matter

    SciTech Connect

    Arndt Schimmelmann; Maria Mastalerz

    2010-03-30

    Isotopically labile organic hydrogen in fossil fuels occupies chemical positions that participate in isotopic exchange and in chemical reactions during thermal maturation from kerogen to bitumen, oil and gas. Carbon-bound organic hydrogen is isotopically far less exchangeable than hydrogen bound to nitrogen, oxygen, or sulfur. We explore why organic hydrogen isotope ratios express a relationship with organic nitrogen isotope ratios in kerogen at low to moderate maturity. We develop and apply new techniques to utilize organic D/H ratios in organic matter fractions and on a molecular level as tools for exploration for fossil fuels and for paleoenvironmental research. The scope of our samples includes naturally and artificially matured substrates, such as coal, shale, oil and gas.

  14. Purification and characterization of Clostridium sordellii hemorrhagic toxin and cross-reactivity with Clostridium difficile toxin A (enterotoxin).

    PubMed Central

    Martinez, R D; Wilkins, T D

    1988-01-01

    Hemorrhagic toxin (toxin HT) was purified from Clostridium sordellii culture filtrate. The purification steps included ultrafiltration through an XM-100 membrane filter and immunoaffinity chromatography, using a monoclonal antibody to toxin A of Clostridium difficile as the ligand. Toxin HT migrated as a major band with a molecular weight of 525,000 and a minor band at 450,000 on nondenaturing gradient polyacrylamide gel electrophoresis. The molecular weight was estimated at 300,000 by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Isoelectric focusing indicated an apparent pI of 6.1. Toxin HT was cytotoxic for cultured cells and lethal for mice by intraperitoneal injection, and it elicited an accumulation of hemorrhagic fluid in rabbit ileal loops. Immunodiffusion analysis revealed a reaction of partial identity between toxins A and HT. Immunological cross-reactivity between these toxins was further demonstrated by immunoblotting and by neutralization of toxin HT biological activity with antibodies to toxin A. A sensitive indirect enzyme-linked immunosorbent assay was used to examine the affinity involved in homologous and heterologous antigen-antibody interactions. Our findings show that toxin HT has biological activities and immunological properties similar to those of toxin A; however, the toxins are not identical. Images PMID:3128481

  15. High lability of sexual system over 250 million years of evolution in morphologically conservative tadpole shrimps

    PubMed Central

    2013-01-01

    Background Sexual system is a key factor affecting the genetic diversity, population structure, genome structure and the evolutionary potential of species. The sexual system androdioecy – where males and hermaphrodites coexist in populations – is extremely rare, yet is found in three crustacean groups, barnacles, a genus of clam shrimps Eulimnadia, and in the order Notostraca, the tadpole shrimps. In the ancient crustacean order Notostraca, high morphological conservatism contrasts with a wide diversity of sexual systems, including androdioecy. An understanding of the evolution of sexual systems in this group has been hampered by poor phylogenetic resolution and confounded by the widespread occurrence of cryptic species. Here we use a multigene supermatrix for 30 taxa to produce a comprehensive phylogenetic reconstruction of Notostraca. Based on this phylogenetic reconstruction we use character mapping techniques to investigate the evolution of sexual systems. We also tested the hypothesis that reproductive assurance has driven the evolution of androdioecy in Notostraca. Results Character mapping analysis showed that sexual system is an extremely flexible trait within Notostraca, with repeated shifts between gonochorism and androdioecy, the latter having evolved a minimum of five times. In agreement with the reproductive assurance hypothesis androdioecious notostracans are found at significantly higher latitudes than gonochoric ones indicating that post glacial re-colonisation may have selected for the higher colonisation ability conferred by androdioecy. Conclusions In contrast to their conserved morphology, sexual system in Notostraca is highly labile and the rare reproductive mode androdioecy has evolved repeatedly within the order. Furthermore, we conclude that this lability of sexual system has been maintained for at least 250 million years and may have contributed to the long term evolutionary persistence of Notostraca. Our results further our understanding of the evolution of androdioecy and indicate that reproductive assurance is a recurrent theme involved in the evolution of this sexual system. PMID:23384124

  16. Functional and Structural Insights of a Staphylococcus aureus Apoptotic-like Membrane Peptide from a Toxin-Antitoxin Module*

    PubMed Central

    Sayed, Nour; Nonin-Lecomte, Sylvie; Réty, Stéphane; Felden, Brice

    2012-01-01

    We report a functional type I toxin-antitoxin (TA) module expressed by a human pathogen, Staphylococcus aureus. TA systems consist of stable toxins and labile antitoxins encoded within small genetic modules widespread in eubacteria and archaea. TA genes provide stress adaptation and protection against DNA loss or invasion. The genes encoding the SprA1 toxic peptide (PepA1) and the SprA1AS RNA antitoxin are within a pathogenicity island on opposite strands and possess a 3? overlap. To prevent peptide toxicity during S. aureus growth, PepA1 expression from stable (half-life > 3 h) SprA1 is repressed by elevated amounts of unstable (half-life = ?10 mn) SprA1AS. In vivo, PepA1 localizes at the bacterial membrane and triggers S. aureus death. Based on NMR and CD data, its solution structure was solved and is a long bent, interrupted helix. Molecular dynamics simulations indicate that PepA1 compaction and helical content fluctuate in accordance with its cytoplasm or membrane location. When inserted into the S. aureus membrane, the PepA1 conformation switches to a ?7-nm-long continuous helix, presumably forming pores to alter membrane integrity. PepA1 expression is induced upon acidic and oxidative stresses by reducing SprA1AS levels. As an altruistic behavior during infection, some cells may induce the expression of that toxin that would facilitate departure from the host immune cells for spreading. PMID:23129767

  17. Effects of phosphate buffer capacity on critical levels and relationships between soil tests and labile phosphate in wheat growing soils

    Microsoft Academic Search

    I. C. R. Holford

    1980-01-01

    Thirty-nine soils from northern New South Wales were used to examine the effects of phosphate buffer capacity on (i) the extraction of labile phosphate by four soil tests, (ii) the relationships between the four soil tests, and (iii) the critical level of each soil test required for near-maximum yield of wheat under field conditions. The results confirmed the principle, recently

  18. On the Labile Memory Buffer in the Attentional Blink: Masking the T2 Representation by Onset Transients Mediates the AB

    ERIC Educational Resources Information Center

    Jannati, Ali; Spalek, Thomas M.; Di Lollo, Vincent

    2011-01-01

    Report of a second target (T2) is impaired when presented within 500 ms of the first (T1). This attentional blink (AB) is known to cause a delay in T2 processing during which T2 must be stored in a labile memory buffer. We explored the buffer's characteristics using different types of masks after T2. These characteristics were inferred by…

  19. Emotional Lability in Children and Adolescents with Attention Deficit/Hyperactivity Disorder (ADHD): Clinical Correlates and Familial Prevalence

    ERIC Educational Resources Information Center

    Sobanski, Esther; Banaschewski, Tobias; Asherson, Philip; Buitelaar, Jan; Chen, Wai; Franke, Barbara; Holtmann, Martin; Krumm, Bertram; Sergeant, Joseph; Sonuga-Barke, Edmund; Stringaris, Argyris; Taylor, Eric; Anney, Richard; Ebstein, Richard P.; Gill, Michael; Miranda, Ana; Mulas, Fernando; Oades, Robert D.; Roeyers, Herbert; Rothenberger, Aribert; Steinhausen, Hans-Christoph; Faraone, Stephen V.

    2010-01-01

    Background: The goal of this study was to investigate the occurrence, severity and clinical correlates of emotional lability (EL) in children with attention deficit/hyperactivity disorder (ADHD), and to examine factors contributing to EL and familiality of EL in youth with ADHD. Methods: One thousand, one hundred and eighty-six children with ADHD…

  20. Tillage and rotational effects on exchangeable and enzyme-labile P forms in conventional and organic cropping systems

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The transformations of crop residues and bio-fertilizers used as primary sources of nutrients for organic grain and forage production are influenced by soil management practices. The effects of management of the near-surface zone on labile phosphorus (P) forms were studied in soil under three organ...

  1. Capture of a Labile Substrate by Expulsion of Water Molecules from the Active Site of Nicotinate Mononucleotide:5,6-

    E-print Network

    Rayment, Ivan

    Capture of a Labile Substrate by Expulsion of Water Molecules from the Active Site of Nicotinate the Departments of Biochemistry and §Bacteriology, University of Wisconsin, Madison, Wisconsin 53706 Nicotinate that the nicotinate moiety and phosphate do not appear to move significantly between reactants and products

  2. A Longitudinal Study of Emotion Regulation, Emotion Lability-Negativity, and Internalizing Symptomatology in Maltreated and Nonmaltreated Children

    ERIC Educational Resources Information Center

    Kim-Spoon, Jungmeen; Cicchetti, Dante; Rogosch, Fred A.

    2013-01-01

    The longitudinal contributions of emotion regulation and emotion lability-negativity to internalizing symptomatology were examined in a low-income sample (171 maltreated and 151 nonmaltreated children, from age 7 to 10 years). Latent difference score models indicated that for both maltreated and nonmaltreated children, emotion regulation was a…

  3. Interactions between anthrax toxin receptors and protective antigen.

    PubMed

    Scobie, Heather M; Young, John A T

    2005-02-01

    Since the anthrax mail attacks of 2001, much has been learned about the interactions between anthrax toxin and its receptors. Two distinct cellular receptors for anthrax toxin have been identified and are designated capillary morphogenesis protein 2 (CMG2) and anthrax toxin receptor/tumor endothelial marker 8 (ATR/TEM8). The molecular details of the toxin-receptor interactions have been revealed through crystallographic, biochemical and genetic studies. In addition, a novel pathway by which anthrax toxin enters cells is starting to be uncovered. PMID:15694864

  4. Effect of land use and longitudinal gradient on carbon quality and lability in the Vesdre River catchment, Belgium

    NASA Astrophysics Data System (ADS)

    Gettel, G. M.; Bravo-Palacios, L.; Gupta, S.

    2011-12-01

    In order to construct accurate terrestrial carbon budgets, it is necessary to understand how land use and river processing affect the export and quality of organic matter. Fluorescence spectroscopy is commonly used to characterize dissolved organic matter (DOM) quality, but how fluorescence characteristics relate to the functional properties of DOM is hardly known. The objectives of this study were to: 1. Characterize DOM quality in diverse land-use types and along a longitudinal gradient in the Vesdre River, Belgium; and 2. At the same sites, relate fluorescence characteristics to DOM lability, which was quantified by microbial respiration and denitrification measurements. The Vesdre basin is 710 km2, contains 429 people/km2, and is characterized by peat, forest, agricultural, and urban land use. Surface water samples from main stem sites (14), tributaries (13), and reservoirs (2) were collected along a 40 km section of the River Vesdre in January 2011. Main stem sites were used to examine the effect of longitudinal processing while tributary sites were used to assess the effects of land use, which included peat, forest, agriculture and urban. Samples were analyzed for DOC concentration, fluorescence, and absorbance spectra. Excitation-emission matrices (EEMs) were generated and analyzed in a 13-component parallel factor analysis (PARAFAC) model. Lability was determined by 42-day incubations in which DOC consumption was fitted with a 3-pool kinetics model, which partitioned the DOM into labile, semi-labile, and refractory pools and generated a decay rate (k) for each pool. The effect of DOM quality on denitrification was also determined using an acetylene block assay in which only excess NO3 was added and samples were normalized to a similar DOC concentration. Mulitivariate regression was used to relate land use and river position to fluorescence properties and DOM lability. High concentration of DOC and intensity of fluorophore C (humic-like fraction, also related to PARAFAC Component 5, C5) in the upstream portion of the catchment were associated with forested and peat lands, whereas low DOC concentration and high intensity of fluorophore T (tryptophan-like fraction, C8) characterized agriculture and urban areas in downstream portion of the catchment. The labile, semi-labile, and refractory pools were related to both land use and DOM quality. Peat was positively correlated with the size of the refractory pool, whereas agriculture and urban land use were positively correlated with the semi-labile pool. The labile pool was positively correlated with C1, while the refractory pool was correlated with C5 and C9 (the humic acid portion). Denitrification rate was correlated with C8. Interestingly, degradation constants (k) from 3- pool model were not correlated with land use or with fluorescence characteristics. In conclusion, this study shows that land-use is important in determining DOM quality, and that in turn, DOM quality affects lability. While not all aspects of the fluorescence properties were important to the functional properties of DOM, fluorescence may be useful in river-network models that aim to relate processing to land use and longitudinal gradient.

  5. (-)-Botryodiplodin, A Unique Ribose Analog Toxin

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Many toxins owe their mechanisms of action to being structural analogs of essential metabolites, messengers or structural components. Examples range from tubo-curare to penicillin. Ribose plays a unique role in the metabolism of living organisms, whether prokaryotes or eukaryotes. It and its deri...

  6. THE TRICHOTHECENE TRIANGLE: TOXINS, GENES AND POPULATIONS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fusarium trichothecenes have been classified based on structural properties. Type A and Type B trichothecenes differ in their A ring oxygenation pattern. Type A trichothecenes have a C-8 hydroxyl (neosolaniol), C-8 ester (T-2 toxin) or no C-8 substitution (diacetoxyscirpenol) and Type B trichothec...

  7. The ins and outs of pertussis toxin.

    PubMed

    Locht, Camille; Coutte, Loic; Mielcarek, Nathalie

    2011-12-01

    Pertussis toxin, produced and secreted by the whooping cough agent Bordetella pertussis, is one of the most complex soluble bacterial proteins. It is actively secreted through the B. pertussis cell envelope by the Ptl secretion system, a member of the widespread type IV secretion systems. The toxin is composed of five subunits (named S1 to S5 according to their decreasing molecular weights) arranged in an A-B structure. The A protomer is composed of the enzymatically active S1 subunit, which catalyzes ADP-ribosylation of the ? subunit of trimeric G proteins, thereby disturbing the metabolic functions of the target cells, leading to a variety of biological activities. The B oligomer is composed of 1S2:1S3:2S4:1S5 and is responsible for binding of the toxin to the target cell receptors and for intracellular trafficking via receptor-mediated endocytosis and retrograde transport. The toxin is one of the most important virulence factors of B. pertussis and is a component of all current vaccines against whooping cough. PMID:21740523

  8. Fungi and fungal toxins as weapons

    Microsoft Academic Search

    R. Russell; M. PATERSON

    2006-01-01

    Recent aggressive attacks on innocent citizens have resulted in governments increasing security. However, there is a good case for prevention rather than reaction. Bioweapons, mycotoxins, fungal biocontrol agents (FBCA), and even pharmaceuticals contain, or are, toxins and need to be considered in the context of the new paradigm. Is it desirable to dis- cuss such issues? None of the fungi

  9. Fungi and fungal toxins as weapons

    Microsoft Academic Search

    R. Russell M. PATERSON

    2006-01-01

    Recent aggressive attacks on innocent citizens have resulted in governments increasing security. However, there is a good case for prevention rather than reaction. Bioweapons, mycotoxins, fungal biocontrol agents (FBCA), and even pharmaceuticals contain, or are, toxins and need to be considered in the context of the new paradigm. Is it desirable to discuss such issues? None of the fungi are

  10. Insecticidal toxins from black widow spider venom

    PubMed Central

    Rohou, A.; Nield, J.; Ushkaryov, Y.A.

    2007-01-01

    The biological effects of Latrodectus spider venom are similar in animals from different phyla, but these symptoms are caused by distinct phylum-specific neurotoxins (collectively called latrotoxins) with molecular masses ranging from 110 to 140 kDa. To date, the venom has been found to contain five insecticidal toxins, termed ?, ?, ?, ? and ?-latroinsectotoxins (LITs). There is also a vertebrate-specific neurotoxin, ?-latrotoxin (?-LTX), and one toxin affecting crustaceans, ?-latrocrustatoxin (?-LCT). These toxins stimulate massive release of neurotransmitters from nerve terminals and act (1) by binding to specific receptors, some of which mediate an exocytotic signal, and (2) by inserting themselves into the membrane and forming ion-permeable pores. Specific receptors for LITs have yet to be identified, but all three classes of vertebrate receptors known to bind ?-LTX are also present in insects. All LTXs whose structures have been elucidated (?-LIT, ?-LIT, ?-LTX and ?-LCT) are highly homologous and have a similar domain architecture, which consists of a unique N-terminal sequence and a large domain composed of 13–22 ankyrin repeats. Three-dimensional (3D) structure analysis, so far done for ?-LTX only, has revealed its dimeric nature and an ability to form symmetrical tetramers, a feature probably common to all LTXs. Only tetramers have been observed to insert into membranes and form pores. A preliminary 3D reconstruction of a ?-LIT monomer demonstrates the spatial similarity of this toxin to the monomer of ?-LTX. PMID:17210168

  11. Tetanus Toxin, a Neuromuscular Blocking Agent

    Microsoft Academic Search

    H. E. Kaeser; A. Saner

    1969-01-01

    IN some cases of infectious tetanus a neuromuscular block with tetraplegia may follow the state of muscle spasms. We suggested1 that this effect was caused by the tetanus toxin itself rather than to an after-effect of muscle relaxants or other drugs. This hypothesis, however, had to be verified by experiments with animals.

  12. Toxins and antimicrobial peptides: Interactions with membranes

    PubMed Central

    Schlamadinger, Diana E.; Gable, Jonathan E.; Kim, Judy E.

    2014-01-01

    The innate immunity to pathogenic invasion of organisms in the plant and animal kingdoms relies upon cationic antimicrobial peptides (AMPs) as the first line of defense. In addition to these natural peptide antibiotics, similar cationic peptides, such as the bee venom toxin melittin, act as nonspecific toxins. Molecular details of AMP and peptide toxin action are not known, but the universal function of these peptides to disrupt cell membranes of pathogenic bacteria (AMPs) or a diverse set of eukaryotes and prokaryotes (melittin) is widely accepted. Here, we have utilized spectroscopic techniques to elucidate peptide-membrane interactions of alpha-helical human and mouse AMPs of the cathelicidin family as well as the peptide toxin melittin. The activity of these natural peptides and their engineered analogs was studied on eukaryotic and prokaryotic membrane mimics consisting of <200-nm bilayer vesicles composed of anionic and neutral lipids as well as cholesterol. Vesicle disruption, or peptide potency, was monitored with a sensitive fluorescence leakage assay. Detailed molecular information on peptide-membrane interactions and peptide structure was further gained through vibrational spectroscopy combined with circular dichroism. Finally, steady-state fluorescence experiments yielded insight into the local environment of native or engineered tryptophan residues in melittin and human cathelicidin embedded in bilayer vesicles. Collectively, our results provide clues to the functional structures of the engineered and toxic peptides and may impact the design of synthetic antibiotic peptides that can be used against the growing number of antibiotic-resistant pathogens. PMID:25593677

  13. Noncosmetic Periocular Therapeutic Applications of Botulinum Toxin

    PubMed Central

    Kaynak-Hekimhan, Pelin

    2010-01-01

    Botulinum toxin blocks acetylcholine release at the neuromuscular junction. The drug which was initially found to be useful in the treatment of strabismus has been extremely effective in the treatment of variety of conditions, both cosmetic and noncosmetic. Some of the noncosmetic uses of botulinum toxin applications include treatment of spastic facial dystonias, temporary treatment of idiopathic or thyroid dysfunction-induced upper eyelid retraction, suppression of undesired hyperlacrimation, induction of temporary ptosis by chemodenervation in facial paralysis, and correction of lower eyelid spastic entropion. Additional periocular uses include control of synchronic eyelid and extraocular muscle movements after aberrant regeneration of cranial nerve palsies. Cosmetic effects of botulinum toxin were discovered accidentally during treatments of facial dystonias. Some of the emerging nonperiocular application for the drug includes treatment of hyperhidrosis, migraine, tension-type headaches, and paralytic spasticity. Some of the undesired side effects of periocular applications of botulinum toxin inlcude ecchymosis, rash, hematoma, headache, flu-like symptoms, nausea, dizziness, loss of facial expression, lower eyelid laxity, dermatochalasis, ectropion, epiphora, eyebrow and eyelid ptosis, lagophthalmos, keratitis sicca, and diplopia. PMID:20616916

  14. Toxins of molds from decaying tomato fruit.

    PubMed Central

    Harwig, J; Scott, P M; Stoltz, D R; Blanchfield, B J

    1979-01-01

    Among 27 mold isolates from decaying tomatoes, culture filtrates or ethyl acetate extracts of 8 isolates grown in yeast extract-sucrose medium were markedly toxic (mortality, greater than 50%) to brine shrimp larvae. The toxicity of six of these isolates could be attributed to the presence of citrinin, tenuazonic acid, or T-2 toxin. Ethyl acetate extracts of five Alternaria isolates and one Fusarium isolate were mutagenic for Salmonella typhimurium strains. In ripe tomatoes inoculated with toxin-producing isolates and incubated at 25 degrees C, one Alternaria alternata isolate produced tenuazonic acid in seven of seven tomatoes at levels of up to 106 micrograms/g and alternariol methyl ether in one of the seven tomatoes at 0.8 microgram/g. Another A. alternata isolate produced tenuazonic acid or alternariol methyl ether at much lower levels in only three of seven tomatoes. Patulin and citrinin were produced by a Penicillium expansum isolate at levels of up to 8.4 and 0.76 microgram/g, respectively. In tomatoes incubated at 15 degrees C, a Fusarium sulphureum isolate produced T-2 toxin, HT-2 toxin, and neosolaniol at levels of up to 37.5, 37.8 and 5.6 micrograms/g, respectively. If these mycotoxins are thermostable, they may occur at detectable levels in tomato products whenever partially moldy tomatoes are used as raw material. PMID:391152

  15. Cyanobacterial toxins: biosynthetic routes and evolutionary roots.

    PubMed

    Dittmann, Elke; Fewer, David P; Neilan, Brett A

    2013-01-01

    Cyanobacteria produce an unparalleled variety of toxins that can cause severe health problems or even death in humans, and wild or domestic animals. In the last decade, biosynthetic pathways have been assigned to the majority of the known toxin families. This review summarizes current knowledge about the enzymatic basis for the production of the hepatotoxins microcystin and nodularin, the cytotoxin cylindrospermopsin, the neurotoxins anatoxin and saxitoxin, and the dermatotoxin lyngbyatoxin. Elucidation of the biosynthetic pathways of the toxins has paved the way for the development of molecular techniques for the detection and quantification of the producing cyanobacteria in different environments. Phylogenetic analyses of related clusters from a large number of strains has also allowed for the reconstruction of the evolutionary scenarios that have led to the emergence, diversification, and loss of such gene clusters in different strains and genera of cyanobacteria. Advances in the understanding of toxin biosynthesis and evolution have provided new methods for drinking-water quality control and may inspire the development of techniques for the management of bloom formation in the future. PMID:23051004

  16. A conserved tetrameric interaction of cry toxin helix ?3 suggests a functional role for toxin oligomerization.

    PubMed

    Lin, Xin; Parthasarathy, Krupakar; Surya, Wahyu; Zhang, Tong; Mu, Yuguang; Torres, Jaume

    2014-07-01

    Crystal (Cry) toxins are widely used for insect control, but their mechanism of toxicity is still uncertain. These toxins can form lytic pores in vitro, and water soluble tetrameric pre-pore intermediates have been reported. Even the precise oligomeric state of the toxin in membranes, trimeric or tetrameric, is still a debated issue. Based on previous reports, we have assumed that interactions between toxin monomers in solution are at least partly mediated by domain I, and we have analyzed in silico the homo-oligomerization tendencies of the domain I ?-helices individually. Using many homologous sequences for each ?-helix, our strategy allows selection of evolutionarily conserved interactions. These interactions appeared only in helices ?3 and ?5, but only ?3 produced a suitably oriented or ?-helical sample in lipid bilayers, forming homotetramers in C14-betaine, and allowing determination of its rotational orientation in lipid bilayers using site-specific infrared dichroism (SSID). The determined orientation in the tetrameric model is in agreement with only one of the evolutionarily conserved models. In addition mutation R99E, which was found to inhibit oligomerization experimentally, greatly destabilized the tetramer in molecular dynamic simulations. In this model, helix 3 is able to form inter-monomer interactions without significant rearrangements of domain I, which is compatible with the available crystal structure of Cry toxins in solution. The model presented here at least partially explains the reported tetrameric oligomerization of Cry toxins in solution and the inhibition of this oligomerization by a synthetic ?3 peptide. PMID:24657394

  17. Higher cytotoxicity of divalent antibody-toxins than monovalent antibody-toxins

    SciTech Connect

    Won, JaeSeon; Nam, PilWon; Lee, YongChan [College of Life Sciences and Graduate School of Biotechnology, Korea University, 5-ga Anam-dong, Sungbuk-gu, Seoul 136-701 (Korea, Republic of)] [College of Life Sciences and Graduate School of Biotechnology, Korea University, 5-ga Anam-dong, Sungbuk-gu, Seoul 136-701 (Korea, Republic of); Choe, MuHyeon, E-mail: choemh@korea.ac.kr [College of Life Sciences and Graduate School of Biotechnology, Korea University, 5-ga Anam-dong, Sungbuk-gu, Seoul 136-701 (Korea, Republic of)] [College of Life Sciences and Graduate School of Biotechnology, Korea University, 5-ga Anam-dong, Sungbuk-gu, Seoul 136-701 (Korea, Republic of)

    2009-04-24

    Recombinant antibody-toxins are constructed via the fusion of a 'carcinoma-specific' antibody fragment to a toxin. Due to the high affinity and high selectivity of the antibody fragments, antibody-toxins can bind to surface antigens on cancer cells and kill them without harming normal cells [L.H. Pai, J.K. Batra, D.J. FitzGerald, M.C. Willingham, I. Pastan, Anti-tumor activities of immunotoxins made of monoclonal antibody B3 and various forms of Pseudomonas exotoxin, Proc. Natl. Acad. Sci. USA 88 (1991) 3358-3362]. In this study, we constructed the antibody-toxin, Fab-SWn-PE38, with SWn (n = 3, 6, 9) sequences containing n-time repeated (G{sub 4}S) between the Fab fragment and PE38 (38 kDa truncated form of Pseudomonas exotoxin A). The SWn sequence also harbored one cysteine residue that could form a disulfide bridge between two Fab-SWn-PE38 monomers. We assessed the cytotoxicity of the monovalent (Fab-SWn-PE38), and divalent ([Fab-SWn-PE38]{sub 2}) antibody-toxins. The cytotoxicity of the dimer against the CRL1739 cell line was approximately 18.8-fold higher than that of the monomer on the ng/ml scale, which was approximately 37.6-fold higher on the pM scale. These results strongly indicate that divalency provides higher cytotoxicity for an antibody-toxin.

  18. Bacillus anthracis Lethal Toxin Reduces Human Alveolar Epithelial Barrier Function

    PubMed Central

    Langer, Marybeth; Duggan, Elizabeth Stewart; Booth, John Leland; Patel, Vineet Indrajit; Zander, Ryan A.; Silasi-Mansat, Robert; Ramani, Vijay; Veres, Tibor Zoltan; Prenzler, Frauke; Sewald, Katherina; Williams, Daniel M.; Coggeshall, Kenneth Mark; Awasthi, Shanjana; Lupu, Florea; Burian, Dennis; Ballard, Jimmy Dale; Braun, Armin

    2012-01-01

    The lung is the site of entry for Bacillus anthracis in inhalation anthrax, the deadliest form of the disease. Bacillus anthracis produces virulence toxins required for disease. Alveolar macrophages were considered the primary target of the Bacillus anthracis virulence factor lethal toxin because lethal toxin inhibits mouse macrophages through cleavage of MEK signaling pathway components, but we have reported that human alveolar macrophages are not a target of lethal toxin. Our current results suggest that, unlike human alveolar macrophages, the cells lining the respiratory units of the lung, alveolar epithelial cells, are a target of lethal toxin in humans. Alveolar epithelial cells expressed lethal toxin receptor protein, bound the protective antigen component of lethal toxin, and were subject to lethal-toxin-induced cleavage of multiple MEKs. These findings suggest that human alveolar epithelial cells are a target of Bacillus anthracis lethal toxin. Further, no reduction in alveolar epithelial cell viability was observed, but lethal toxin caused actin rearrangement and impaired desmosome formation, consistent with impaired barrier function as well as reduced surfactant production. Therefore, by compromising epithelial barrier function, lethal toxin may play a role in the pathogenesis of inhalation anthrax by facilitating the dissemination of Bacillus anthracis from the lung in early disease and promoting edema in late stages of the illness. PMID:23027535

  19. Acid-labile sulfides in shallow marine bottom sediments: A review of the impact on ecosystems in the Azov Sea, the NE Black Sea shelf and NW Adriatic lagoons

    NASA Astrophysics Data System (ADS)

    Sorokin, Yu. I.; Zakuskina, O. Yu

    2012-02-01

    Acid-labile sulfides (LS) increase in bottom sediments at sites in the Azov Sea, at the NE Black Sea shelf and in the coastal lagoons of NW Adriatic Sea experiencing direct impacts of anthropogenic pollution. Fresh anthropogenic organic matter stimulates the bacterial sulfate reduction and here the rate of the LS production overcomes their loss during the oxidation and pyritization. This results in the expansion of reduced sediment layer up to the bottom surface. The LS concentration in the reduced sediments varies between 300 and 2000 mg S l -1 of wet silt depending on the size of pollution loading and on the rate of sedimentation. In the oxidized sediments away from the direct pollution impact, the LS concentration did not exceed 100-150 mg S l -1. Being a strong cytochrome toxin, the LS adversely affect the coastal ecosystems. The concentrations over 600 mg S l -1 result in quasi total benthic mortality whereas >300-400 mg S l -1 depletes the benthic faunal abundance and taxonomic diversity. Accumulation of the LS in sediments also induces nocturnal hypoxia and stimulates domination of toxic cyanobacteria in the pelagic phytocenoses.

  20. Comparative proteomic analysis of Aedes aegypti larval midgut after intoxication with Cry11Aa toxin from Bacillus thuringiensis.

    PubMed

    Cancino-Rodezno, Angeles; Lozano, Luis; Oppert, Cris; Castro, Julieta I; Lanz-Mendoza, Humberto; Encarnación, Sergio; Evans, Amy E; Gill, Sarjeet S; Soberón, Mario; Jurat-Fuentes, Juan L; Bravo, Alejandra

    2012-01-01

    Cry toxins produced by Bacillus thuringiensis bacteria are environmentally safe alternatives to control insect pests. They are pore-forming toxins that specifically affect cell permeability and cellular integrity of insect-midgut cells. In this work we analyzed the defensive response of Aedes aegypti larva to Cry11Aa toxin intoxication by proteomic and functional genomic analyses. Two dimensional differential in-gel electrophoresis (2D-DIGE) was utilized to analyze proteomic differences among A. aegypti larvae intoxicated with different doses of Cry11Aa toxin compared to a buffer treatment. Spots with significant differential expression (p<0.05) were then identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS), revealing 18 up-regulated and seven down-regulated proteins. The most abundant subcategories of differentially expressed proteins were proteins involved in protein turnover and folding, energy production, and cytoskeleton maintenance. We selected three candidate proteins based on their differential expression as representatives of the different functional categories to perform gene silencing by RNA interference and analyze their functional role. The heat shock protein HSP90 was selected from the proteins involved in protein turnover and chaperones; actin, was selected as representative of the cytoskeleton protein group, and ATP synthase subunit beta was selected from the group of proteins involved in energy production. When we affected the expression of ATP synthase subunit beta and actin by silencing with RNAi the larvae became hypersensitive to toxin action. In addition, we found that mosquito larvae displayed a resistant phenotype when the heat shock protein was silenced. These results provide insight into the molecular components influencing the defense to Cry toxin intoxication and facilitate further studies on the roles of identified genes. PMID:22615881

  1. The impact of environmental toxins on predator-prey dynamics.

    PubMed

    Huang, Qihua; Wang, Hao; Lewis, Mark A

    2015-08-01

    Predators and prey may be simultaneously exposed to environmental toxins, but one may be more susceptible than the other. To study the effects of environmental toxins on food web dynamics, we develop a toxin-dependent predator-prey model that combines both direct and indirect toxic effects on two trophic levels. The direct effects of toxins typically reduce organism abundance by increasing mortality or reducing fecundity. Such direct effects, therefore, alter both bottom-up food availability and top-down predatory ability. However, the indirect effects, when mediated through predator-prey interactions, may lead to counterintuitive effects. This study investigates how the balance of the classical predator-prey dynamics changes as a function of environmental toxin levels. While high toxin concentrations are shown to be harmful to both species, possibly leading to extirpation of both species, intermediate toxin concentrations may affect predators disproportionately through biomagnification, leading to reduced abundance of predators and increased abundance of the prey. This counterintuitive effect significantly increases biomass at the lower trophic level. Environmental toxins may also reduce population variability by preventing populations from fluctuating around a coexistence equilibrium. Finally, environmental toxins may induce bistable dynamics, in which different initial population levels produce different long-term outcomes. Since our toxin-dependent predator-prey model is general, the theory developed here not only provides a sound foundation for population or community effects of toxicity, but also could be used to help develop management strategies to preserve and restore the integrity of contaminated habitats. PMID:25916557

  2. Evaluating Multiple Drivers of Soil Organic Matter Lability and Structure in a Sub-Alpine Forest Ecosystem

    NASA Astrophysics Data System (ADS)

    Hall, E.; Fegel, T. S., II; Boot, C. M.

    2014-12-01

    Aeolian deposition of reactive nitrogen (N) is reaching even the most remote ecosystems. There has been an abundance of research investigating how these subsidies of reactive N may alter fundamental ecosystem characteristics such as soil organic matter (SOM) pool size. Previous studies have reported that additions of reactive N have the potential to both increase and decrease SOM content. While there are a series of different variables that may affect the size of the SOM pool it has been suggested that the lability or recalcitrance of the SOM may be related to its chemical composition (kind and relative abundance of constituent molecules). To address this we sampled 6 experimental plots in a sub-alpine forest in Rocky Mountain National Park (3 control and 3 treated with reactive N for 18 years) during two months in the summers of 2011 and 2012. We found the SOM content of the control plots was greater than that of the experimental plots. To assess lability of each SOM sample we extracted the SOM from each plot with water and incubated the dissolved organic carbon with a common aquatic microbial community from a lake within the watershed. To assess structure of the SOM pool we used ultra performance liquid chromatography (UPLC) coupled with MS of each extract before incubation with the bacterial community. The dissolved component of the SOM showed clear differences in lability both in total quantity and rate of decomposition during incubation with aquatic microorganisms. Principle components analysis indicated season was a stronger driver of DOM composition than fertilization, describing the majority of the variability between July and September 2012. When samples were considered within a season and year there were additional differences in both lability and composition of DOM. Here we evaluate the relative influence of inter- and intra-annual variability and reactive N on both the characteristics and composition of SOM. By linking UPLC-MS with a functional assay of lability we attempt to define chemical characteristics of lability that can be assessed across ecosystems. Doing so will allow us to better understand linked biogeochemical cycles (C and N) across a wide range of soil ecosystems.

  3. New insights into the biological effects of anthrax toxins: linking cellular to organismal responses

    E-print Network

    Nizet, Victor

    Review New insights into the biological effects of anthrax toxins: linking cellular to organismal, and brain. In this review, we examine the various biological effects of anthrax toxins, focusing The anthrax toxins lethal toxin (LT) and edema toxin (ET) are essential virulence factors produced by Bacillus

  4. New insights into the biological effects of anthrax toxins: linking cellular to organismal responses

    Microsoft Academic Search

    Annabel Guichard; Victor Nizet; Ethan Bier

    The anthrax toxins lethal toxin (LT) and edema toxin (ET) are essential virulence factors produced by Bacillus anthracis. These toxins act during two distinct phases of anthrax infection. During the first, prodromal phase, which is often asymptomatic, anthrax toxins act on cells of the immune system to help the pathogen establish infection. Then, during the rapidly progressing (or fulminant) stage

  5. Effect of toxin A and B of Clostridium difficile on rabbit ileum and colon

    Microsoft Academic Search

    T J Mitchell; J M Ketley; S C Haslam; J Stephen; D W Burdon; D C Candy; R Daniel

    1986-01-01

    The effect of purified toxin A and partially purified toxin B on rabbit ileum and colon was investigated. Toxin A caused tissue damage which was followed by permeability changes and fluid accumulation in both tissues. Toxin A did not increase the permeability of the colon to the extent observed for ileum; secreted fluid contained less protein of plasma origin. Toxin

  6. Isolation of the toxin in Daubentonia longifolia

    E-print Network

    Robey, Ashley

    1925-01-01

    THE ISOLATION OF THE TOXIN IN DAUBENTONIA LONGIFOLIA A THESIS SUBMITTED TO THE FACULTY OF THE AGRICULTURAL AND MECHANICAL COLLEGE OF TEXAS IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE BY ASHLEY ROBEY&B. S... . r the following classi fication by Small Sub-kin"dom, Spermatophyta; class Angiospermae; sub-class, Dicoteledons; order, 3osales; family, Vabacsae; tribe Galageae; genus, Daubentonia (D. C. ); species, Longifolia ( Cav. D. C. ). It is a shrub...

  7. Cyanobacterial toxins in Canadian freshwaters: A review

    Microsoft Academic Search

    B. G. Kotak; R. W. Zurawell

    2007-01-01

    Cyanobacterial toxins are a serious water quality concern in productive water bodies worldwide. Microcystins (MCs), which are hepatotoxins, are prevalent in Canadian freshwaters while the occurrence of neurotoxins anatoxin-a, anatoxin-a(s) and saxitoxin appears to be much less common. Concentrations of microcystin-LR (MCLR), presumed to be the most common of the more than 70 MC analogues, are highly variable in phytoplankton

  8. Saxitoxins (PSP toxins) in Danish lakes

    Microsoft Academic Search

    Hanne Kaas; Peter Henriksen

    2000-01-01

    The occurrence of neurotoxic cyanobacteria and saxitoxins in Danish lakes was investigated from 104 phytoplankton samples representing 96 localities. Mouse bioassays demonstrated neurotoxicity in 11 localities (13 samples) of which eight (10 samples) contained saxitoxins and the remaining three anatoxin-a(s). The common cyanobacterial neurotoxin anatoxin-a was not detected. The toxin profiles of the samples containing saxitoxins were characterised using standards

  9. The medicinal use of venoms and toxins.

    PubMed

    Palatty, Princy Louis; Saldanha, Elroy

    2013-01-01

    Venoms have long since been known to have therapeutic value. Venoms have been characterised into their individual components and each of their functions extensively studied. These components of venoms and toxins show potential as antihypertensive, anticoagulant, fibrinolytic, anticancerous, immunomodulators, muscle relaxant, etc. Only the most promising and FDA approved and therapeutic options have been discussed here eg, hannalgesin, epibatidine, ancrod, lepirudin, fibrolase, lebecetin, pseutarin, captopril, eristostatin, botox. PMID:24000509

  10. Use of botulinum toxin in musculoskeletal pain

    PubMed Central

    Singh, Jasvinder A

    2013-01-01

    Chronic musculoskeletal pain is a common cause of chronic pain, which is associated with a total cost of $635 billion per year in the U.S. Emerging evidence suggests an anti-nociceptive action of botulinum toxin, independent of its muscle paralyzing action. This review provides a summary of data from both non-randomized and randomized clinical studies of botulinum toxin in back pain and various osteoarticular conditions, including osteoarthritis, tennis elbow, low back pain and hand pain. Three randomized controlled trials (RCTs) of small sizes provide evidence of short-term efficacy of a single intra-articular injection of 100 units of botulinum toxin A (BoNT/A) for the relief of pain and the improvement of both function and quality of life in patients with chronic joint pain due to arthritis. Three RCTs studied intramuscular BoNT/A for tennis elbow with one showing a significant improvement in pain relief compared with placebo, another one showing no difference from placebo, and the third finding that pain and function improvement with BoNT/A injection were similar to those obtained with surgical release. One RCT of intramuscular BoNT/A for low back pain found improvement in pain and function compared to placebo. Single RCTs using local injections of BoNT in patients with either temporomandibular joint (TMJ) pain or plantar fasciitis found superior efficacy compared to placebo. One RCT of intramuscular BoNT/B in patients with hand pain and carpal tunnel syndrome found improvement in pain in both BoNT/B and placebo groups, but no significant difference between groups. Most evidence is based on small studies, but the use of BoNT is supported by a single, and sometimes up to three, RCTs for several chronic musculoskeletal pain conditions. This indicates that botulinum toxin may be a promising potential new treatment for chronic refractory musculoskeletal pain. Well-designed large clinical trials are needed. PMID:24715952

  11. Perfringolysin O: The Underrated Clostridium perfringens Toxin?

    PubMed Central

    Verherstraeten, Stefanie; Goossens, Evy; Valgaeren, Bonnie; Pardon, Bart; Timbermont, Leen; Haesebrouck, Freddy; Ducatelle, Richard; Deprez, Piet; Wade, Kristin R.; Tweten, Rodney; Van Immerseel, Filip

    2015-01-01

    The anaerobic bacterium Clostridium perfringens expresses multiple toxins that promote disease development in both humans and animals. One such toxin is perfringolysin O (PFO, classically referred to as ? toxin), a pore-forming cholesterol-dependent cytolysin (CDC). PFO is secreted as a water-soluble monomer that recognizes and binds membranes via cholesterol. Membrane-bound monomers undergo structural changes that culminate in the formation of an oligomerized prepore complex on the membrane surface. The prepore then undergoes conversion into the bilayer-spanning pore measuring approximately 250–300 Å in diameter. PFO is expressed in nearly all identified C. perfringens strains and harbors interesting traits that suggest a potential undefined role for PFO in disease development. Research has demonstrated a role for PFO in gas gangrene progression and bovine necrohemorrhagic enteritis, but there is limited data available to determine if PFO also functions in additional disease presentations caused by C. perfringens. This review summarizes the known structural and functional characteristics of PFO, while highlighting recent insights into the potential contributions of PFO to disease pathogenesis. PMID:26008232

  12. Acid-Labile Poly(glycidyl methacrylate)-Based Star Gene Vectors.

    PubMed

    Yang, Yan-Yu; Hu, Hao; Wang, Xing; Yang, Fei; Shen, Hong; Xu, Fu-Jian; Wu, De-Cheng

    2015-06-10

    It was recently reported that ethanolamine-functionalized poly(glycidyl methacrylate) (PGEA) possesses great potential applications in gene therapy due to its good biocompatibility and high transfection efficiency. Importing responsivity into PGEA vectors would further improve their performances. Herein, a series of responsive star-shaped vectors, acetaled ?-cyclodextrin-PGEAs (A-CD-PGEAs) consisting of a ?-CD core and five PGEA arms linked by acid-labile acetal groups, were proposed and characterized as therapeutic pDNA vectors. The A-CD-PGEAs owned abundant hydroxyl groups to shield extra positive charges of A-CD-PGEAs/pDNA complexes, and the star structure could decrease charge density. The incorporation of acetal linkers endowed A-CD-PGEAs with pH responsivity and degradation. In weakly acidic endosome, the broken acetal linkers resulted in decomposition of A-CD-PGEAs and morphological transformation of A-CD-PGEAs/pDNA complexes, lowering cytotoxicity and accelerating release of pDNA. In comparison with control CD-PGEAs without acetal linkers, A-CD-PGEAs exhibited significantly better transfection performances. PMID:25993557

  13. A novel nanoparticulate system for sustained delivery of acid-labile lansoprazole.

    PubMed

    Alai, Milind Sadashiv; Lin, Wen Jen

    2013-11-01

    In the present study, an effort was made to develop the Eudragit RS100 based nanoparticulate system for sustained delivery of an acid-labile drug, lansoprazole (LPZ). LPZ-loaded Eudragit RS100 nanoparticles (ERSNPs) were prepared by oil-in-water emulsion-solvent evaporation method. The effects of various formulation variables such as polymer concentration, drug amount and solvent composition on physicochemical performance of nanoparticles and in vitro drug release were investigated. All nanoparticles were spherical with particle size 198.9 ± 8.6-376.9 ± 5.6 nm and zeta potential +35.1 ± 1.7 to +40.2 ± 0.8 mV. The yield of nanoparticles was unaffected by change of these three variables. However, the drug loading and encapsulation efficiency were affected by polymer concentration and drug amount. On the other hand, the particle size of nanoparticles was significantly affected by polymer concentration and internal phase composition due to influence of droplet size during emulsification process. All nanoparticles prolonged drug release for 24h which was dominated by a combination of drug diffusion and polymer chain relaxation. The fastest and the slowest release rates were observed in C2-1002-10/0 and C8-4001-10/0, respectively, based on the release rate constant (k). Thus, the developed nanoparticles possessed a potential as a nano-carrier to sustain drug delivery for treatment of acid related disorders. PMID:23867305

  14. Determination of labile copper, cobalt, and chromium in textile mill wastewater

    SciTech Connect

    Crain, J.S.; Essling, A.M.; Kiely, J.T. [and others

    1997-01-01

    Copper, chromium, and cobalt species present in filtered wastewater effluent were separated by cation exchange and reverse phase chromatography. Three sample fractions were obtained: one containing metal cations (i.e., trivalent Cr, divalent Cu, and divalent Co), one containing organic species (including metallized dyes), and one containing other unretained species. The metal content of each fraction was determined by inductively coupled plasma atomic emission spectroscopy (ICP-AES). The sum of the corrected data was compared to the metal content of a filtered effluent aliquot digested totally with fuming sulfuric acid. Other aliquots of the filtered effluent were spiked with the metals of interest and digested to confirm chemical yield and accuracy. Method detection limits were consistently below 20 {mu}g L{sup -1} for Cu, 30 {mu}g L{sup -1} for Co, and 10 {mu}g L{sup -1} for Cr. Spike recoveries for undifferentiated Cu and Cr were statistically indistinguishable from unity; although Co spike recoveries were slightly low ({approximately}95%), its chemical yield was 98%. Copper retention on the sodium sulfonate cation exchange resin was closely correlated with the [EDTA]/[Cu] ratio, suggesting that metals retained upon the cation exchange column were assignable to labile metal species; however, mass balances for all three elements, though reasonable ({approximately}90%), were significantly different from unity. Mechanical factors may have contributed to the material loss, but other data suggest that some metal species reacted irreversibly with the reverse phase column. 3 refs., 2 figs., 4 tabs.

  15. Labile organic carbon regulates phosphorus release from eroded soil transported into anaerobic coastal systems.

    PubMed

    Lehtoranta, Jouni; Ekholm, Petri; Wahlström, Stella; Tallberg, Petra; Uusitalo, Risto

    2015-03-01

    Coastal eutrophication is expected to increase due to expanding and intensifying agriculture which causes a large amount of soil-associated P to be transported into aquatic systems. We performed anaerobic long-term incubations on field soil to mimic the conditions that eroded soil encounters in brackish sediments. The release of P from soil increased with the amount of labile organic C (acetate) addition and decreased with the soil/solution ratio. We deduce that in less-productive brackish systems, microbial Fe reduction allows for the maintenance of the coupled cycling of Fe and P and restricts the amount of P entering the oxic water. In more eutrophic systems, the formation of Fe sulfides as a result of SO4 reduction inactivates Fe, and leads to a higher release of P, thus generating an adverse feedback effect. The dependence of the fate of soil-bound Fe and P on the trophic status of the receiving water should be recognized in eutrophication management. PMID:25681983

  16. Nitric oxide is necessary for labilization of a consolidated context memory during reconsolidation in terrestrial snails.

    PubMed

    Balaban, Pavel M; Roshchin, Matvey; Timoshenko, Alia K; Gainutdinov, Khalil L; Bogodvid, Tatiana K; Muranova, Lyudmila N; Zuzina, Alena B; Korshunova, Tatiana A

    2014-09-01

    Nitric oxide (NO) is known to be involved in associative memory formation. We investigated the influence of blocking NO function on the reconsolidation of context memory in terrestrial snails (Helix lucorum L.). After a 10 day session of electric shocks in one context only, context memory in snails was observed in test sessions as the significant difference of amplitudes of withdrawal responses to tactile stimuli in two different contexts. After a 1 day rest, a session of 'reminding' was performed, preceded by injection in different groups of the snails with either vehicle or combination of the protein synthesis blocker anisomycin (ANI) with one of the following drugs: the NO scavenger carboxy-PTIO, the NO-synthase inhibitors N-omega-nitro-L-arginin, nitroindazole and NG-nitro-L-arginine methyl ester hydrochloride, or the NO donor S-nitroso-N-acetyl-DL-penicillamine. Testing the context memory at different time intervals after the reminder under ANI injection showed that the context memory was impaired at 24 h and later, whereas the reminder under combined injection of ANI and each of the NO-synthase inhibitors used or the NO scavenger showed no impairment of long-term context memory. Injection of the NO donor S-nitroso-N-acetyl-DL-penicillamine with or without reminder had no effect on context memory. The results obtained demonstrated that NO is necessary for labilization of a consolidated context memory. PMID:24910164

  17. Facile synthesis of acid-labile polymers with pendent ortho esters.

    PubMed

    Cheng, Jing; Ji, Ran; Gao, Shi-Juan; Du, Fu-Sheng; Li, Zi-Chen

    2012-01-01

    This work presents a facile approach for preparation of acid-labile and biocompatible polymers with pendent cyclic ortho esters, which is based on the efficient and mild reactions between cyclic ketene acetal (CKA) and hydroxyl groups. Three CKAs, 2-ethylidene-1,3-dioxane (EDO), 2-ethylidene-1,3-dioxolane (EDL), and 2-ethylidene-4- methyl-1,3-dioxolane (EMD) were prepared from the corresponding cyclic vinyl acetals by catalytic isomerization of the double bond. The reaction of CKAs with different alcohols and diols was examined using trace of p-toluenesulfonic acid as a catalyst. For the monohydroxyl alcohols, cyclic ortho esters were formed by simple addition of the hydroxyl group toward CKAs with ethanol showing a much greater reactivity than iso-propanol. When 1,2- or 1,3-diols were used to react with the CKAs, we observed the isomerized cyclic ortho esters besides the simple addition products. Biocompatible polyols, that is, poly(2-hydroxyethyl acrylate) (PHEA) and poly(vinyl alcohol) (PVA) were then modified with CKAs, and the degree of substitution of the pendent ortho esters can be easily tuned by changing feed ratio. Both the small molecule ortho esters and the CKA-modified polymers demonstrate the pH-dependent hydrolysis profiles, which depend also on the chemical structure of the ortho esters as well as the polymer hydrophobicity. PMID:22176024

  18. Development and Bioorthogonal Activation of Palladium-Labile Prodrugs of Gemcitabine

    PubMed Central

    2014-01-01

    Bioorthogonal chemistry has become one of the main driving forces in current chemical biology, inspiring the search for novel biocompatible chemospecific reactions for the past decade. Alongside the well-established labeling strategies that originated the bioorthogonal paradigm, we have recently proposed the use of heterogeneous palladium chemistry and bioorthogonal Pd0-labile prodrugs to develop spatially targeted therapies. Herein, we report the generation of biologically inert precursors of cytotoxic gemcitabine by introducing Pd0-cleavable groups in positions that are mechanistically relevant for gemcitabine’s pharmacological activity. Cell viability studies in pancreatic cancer cells showed that carbamate functionalization of the 4-amino group of gemcitabine significantly reduced (>23-fold) the prodrugs’ cytotoxicity. The N-propargyloxycarbonyl (N-Poc) promoiety displayed the highest sensitivity to heterogeneous palladium catalysis under biocompatible conditions, with a reaction half-life of less than 6 h. Zebrafish studies with allyl, propargyl, and benzyl carbamate-protected rhodamines confirmed N-Poc as the most suitable masking group for implementing in vivo bioorthogonal organometallic chemistry. PMID:24867590

  19. An intermetallic Au24Ag20 superatom nanocluster stabilized by labile ligands.

    PubMed

    Wang, Yu; Su, Haifeng; Xu, Chaofa; Li, Gang; Gell, Lars; Lin, Shuichao; Tang, Zichao; Häkkinen, Hannu; Zheng, Nanfeng

    2015-04-01

    An intermetallic nanocluster containing 44 metal atoms, Au24Ag20(2-SPy)4(PhC?C)20Cl2, was successfully synthesized and structurally characterized by single-crystal analysis and density funtional theory computations. The 44 metal atoms in the cluster are arranged as a concentric three-shell Au12@Ag20@Au12 Keplerate structure having a high symmetry. For the first time, the co-presence of three different types of anionic ligands (i.e., phenylalkynyl, 2-pyridylthiolate, and chloride) was revealed on the surface of metal nanoclusters. Similar to thiolates, alkynyls bind linearly to surface Au atoms using their ?-bonds, leading to the formation of two types of surface staple units (PhC?C-Au-L, L = PhC?C(-) or 2-pyridylthiolate) on the cluster. The co-presence of three different surface ligands allows the site-specific surface and functional modification of the cluster. The lability of PhC?C(-) ligands on the cluster was demonstrated, making it possible to keep the metal core intact while removing partial surface capping. Moreover, it was found that ligand exchange on the cluster occurs easily to offer various derivatives with the same metal core but different surface functionality and thus different solubility. PMID:25803406

  20. Assessment of labile plasma iron in patients who undergo hematopoietic stem cell transplantation.

    PubMed

    Naoum, Flávio Augusto; Espósito, Breno Pannia; Ruiz, Lílian Piron; Ruiz, Milton Artur; Tanaka, Paula Yurie; Sobreira, Juliana Tavora; Cançado, Rodolfo Delfini; de Barros, José Carlos

    2014-01-01

    Body iron disorders have been reported after myeloablative conditioning in patients undergoing hematopoietic stem cell transplantation (HSCT). There is a concern that labile plasma iron (LPI), the redox-active form of iron, can be involved in the occurrence of toxicity and other complications commonly observed in the early post-HSCT period. In order to better understand the LPI kinetics and its determinants and implications, we undertook sequential LPI determinations before and after conditioning until engraftment in 25 auto-HSCT patients. Increased LPI was present in only 5 patients before starting conditioning. Shortly after conditioning, LPI levels were increased in 23 patients, with peak at day 0, returning to normal range upon engraftment in 21 patients. Overall, LPI levels correlated weakly with serum ferritin and more strongly with transferrin saturation; however, both parameters were apparently not applicable as surrogate markers for increased LPI. Although this was a small cohort, logistic regression suggested that baseline LPI levels could predict occurrence of grade III or IV toxicity. In conclusion, LPI kinetics is influenced by aplasia following conditioning and engraftment. Measuring LPI before starting conditioning can offer an opportunity to predict toxicity and, perhaps, the need for chelation therapy. PMID:24335268

  1. Methyl methanesulfonate (MMS) produces heat-labile DNA damage but no detectable in vivo DNA double-strand breaks

    Microsoft Academic Search

    Cecilia Lundin; Matthew North; Klaus Erixon; Kevin Walters; Dag Jenssen; Alastair S. H. Goldman; Thomas Helleday

    2005-01-01

    Homologous recombination (HR) deficient cells are sensitive to methyl methanesulfonate (MMS). HR is usually involved in the repair of DNA double-strand breaks (DSBs) in Saccharomyces cerevisiae implying that MMS somehow induces DSBs in vivo. Indeed there is evidence, based on pulsed-field gel electro- phoresis (PFGE), that MMS causes DNA fragmenta- tion. However, the mechanism through which MMS induces DSBs has

  2. Encapsulation of microbiologically labile compounds within macromolecular organic matter in sedimentary systems as a means of preservation

    SciTech Connect

    Hatcher, P.G.; Knicker, H.; Rio, J.C. del [Pennsylvania State Univ., University Park, PA (United States)] [and others

    1996-12-31

    The preservation of microbiologically labile organic compounds in the sedimentary geological record for times that are longer than what would be expected is a phenomenon recently touted as being due to physical entrapment within mesopores of mineral particles. Presumably, the mesopores offer protection from the action of microbial enzymes. Our recent studies of the preservation of organic compounds in mineral-free sediments indicates that protection from the action of enzymes can also be afforded by encapsulation within macromolecular organic matter, especially if this organic matter is strongly hydrophobic. The basis of this conclusion centers upon the observation that labile proteinaceous materials survive in these sediments for extended periods of time as deduced by solid-state {sup 15}N NMR and thermochemolysis with tetramethylammonium hydroxide.

  3. Suppression of UVA-mediated release of labile iron by epicatechin--a link to lysosomal protection.

    PubMed

    Basu-Modak, Sharmila; Ali, Dalia; Gordon, Matt; Polte, Tobias; Yiakouvaki, Anthie; Pourzand, Charareh; Rice-Evans, Catherine; Tyrrell, Rex M

    2006-10-15

    UVA (320-380 nm) radiation generates an oxidative stress in cells and leads to an immediate release of potentially damaging labile iron pools in human skin cells. Treatment of cultured skin fibroblasts for several hours with physiologically relevant concentrations of either epicatechin (EC), a flavonoid plant constituent present in foods, or methylated epicatechin (3'-O-methyl epicatechin, MeOEC), its major human metabolite, prevents this iron release. The similarity of the effectiveness of EC and MeOEC argues against chelation as the mechanism of iron removal. Evidence based on measurements of lysosomal integrity strongly supports the hypothesis that the catechins protect against lysosomal destruction by UVA. Such damage would normally lead to protease release, which has been previously shown to cause ferritin degradation and release of labile iron. PMID:17015166

  4. Amiodarone and bepridil inhibit anthrax toxin entry into host cells.

    PubMed

    Sanchez, Ana M; Thomas, Diane; Gillespie, Eugene J; Damoiseaux, Robert; Rogers, Joseph; Saxe, Jonathan P; Huang, Jing; Manchester, Marianne; Bradley, Kenneth A

    2007-07-01

    Anthrax lethal toxin is one of the fundamental components believed to be responsible for the virulence of Bacillus anthracis. In order to find novel compounds with anti-lethal toxin properties, we used a cell-based assay to screen a collection of approximately 500 small molecules. Nineteen compounds that blocked lethal toxin-mediated killing of RAW 264.7 macrophages were identified, and we report here on the characterization of the two most potent antitoxic compounds, amiodarone and bepridil. These drugs are used to treat cardiac arrhythmia or angina in humans at doses similar to those that provide protection against lethal toxin in vitro. Our results support a model whereby the antitoxic properties of both drugs result from their ability to block endosomal acidification, thereby blocking toxin entry. Amiodarone was tested in vivo and found to significantly increase survival of lethal toxin-challenged Fischer rats. PMID:17485504

  5. Anthrax toxins: A paradigm of bacterial immune suppression.

    PubMed

    Baldari, Cosima T; Tonello, Fiorella; Paccani, Silvia Rossi; Montecucco, Cesare

    2006-09-01

    Several species of microorganism have developed immune evasion and/or immunosuppression strategies. Bacillus anthracis secretes two toxins, edema toxin and lethal toxin, that enter the cytosol of almost every cell type, including the cells of the innate and adaptive immune systems, and subvert cell signaling. Edema toxin causes a consistent elevation of cyclic adenosine monophosphate, whereas lethal toxin cleaves most isoforms of mitogen-activated protein kinase kinases. In a concerted manner, these toxins alter major signaling pathways involved in the development of immune-cell effector functions, with the inhibition of bacterial clearance by phagocytes and of B. anthracis-specific responses. Thus, B. anthracis can invade the host, with ensuing massive bacteremia and toxemia. Here, we review the specific effects of B. anthracis on neutrophils, macrophages, dendritic cells, T- and B-lymphocytes. PMID:16861036

  6. Cytoskeleton as an Emerging Target of Anthrax Toxins

    PubMed Central

    Trescos, Yannick; Tournier, Jean-Nicolas

    2012-01-01

    Bacillus anthracis, the agent of anthrax, has gained virulence through its exotoxins produced by vegetative bacilli and is composed of three components forming lethal toxin (LT) and edema toxin (ET). So far, little is known about the effects of these toxins on the eukaryotic cytoskeleton. Here, we provide an overview on the general effects of toxin upon the cytoskeleton architecture. Thus, we shall discuss how anthrax toxins interact with their receptors and may disrupt the interface between extracellular matrix and the cytoskeleton. We then analyze what toxin molecular effects on cytoskeleton have been described, before discussing how the cytoskeleton may help the pathogen to corrupt general cell processes such as phagocytosis or vascular integrity. PMID:22474568

  7. Cytoskeleton as an emerging target of anthrax toxins.

    PubMed

    Trescos, Yannick; Tournier, Jean-Nicolas

    2012-02-01

    Bacillus anthracis, the agent of anthrax, has gained virulence through its exotoxins produced by vegetative bacilli and is composed of three components forming lethal toxin (LT) and edema toxin (ET). So far, little is known about the effects of these toxins on the eukaryotic cytoskeleton. Here, we provide an overview on the general effects of toxin upon the cytoskeleton architecture. Thus, we shall discuss how anthrax toxins interact with their receptors and may disrupt the interface between extracellular matrix and the cytoskeleton. We then analyze what toxin molecular effects on cytoskeleton have been described, before discussing how the cytoskeleton may help the pathogen to corrupt general cell processes such as phagocytosis or vascular integrity. PMID:22474568

  8. Overview of Scorpion Species from China and Their Toxins

    PubMed Central

    Cao, Zhijian; Di, Zhiyong; Wu, Yingliang; Li, Wenxin

    2014-01-01

    Scorpions are one of the most ancient groups of terrestrial animals. They have maintained a steady morphology over more than 400 million years of evolution. Their venom arsenals for capturing prey and defending against predators may play a critical role in their ancient and conservative appearance. In the current review, we present the scorpion fauna of China: 53 species covering five families and 12 genera. We also systematically list toxins or genes from Chinese scorpion species, involving eight species covering four families. Furthermore, we review the diverse functions of typical toxins from Chinese scorpion species, involving Na+ channel modulators, K+ channel blockers, antimicrobial peptides and protease inhibitors. Using scorpion species and their toxins from China as an example, we build the bridge between scorpion species and their toxins, which helps us to understand the molecular and functional diversity of scorpion venom arsenal, the dynamic and functional evolution of scorpion toxins, and the potential relationships of scorpion species and their toxins. PMID:24577583

  9. Impact of labile and recalcitrant carbon treatments on available nitrogen and plant communities in a semiarid ecosystem.

    PubMed

    Burke, I C; Bontti, E E; Barrett, J E; Lowe, P N; Lauenroth, W K; Riggle, R

    2013-04-01

    In a 10-year study, we assessed the influence of five carbon (C) treatments on the labile C and nitrogen (N) pools of historically N-enriched plots on the Shortgrass Steppe Long Term Ecological Research site located in northeastern Colorado. For eight years, we applied sawdust, sugar, industrial lignin, sawdust + sugar, and lignin + sugar to plots that had received N and water additions in the early 1970s. Previous work showed that past water and N additions altered plant species composition and enhanced rates of nutrient cycling; these effects were still apparent 25 years later. We hypothesized that labile C amendments would stimulate microbial activity and suppress rates of N mineralization, whereas complex forms of carbon (sawdust and lignin) could enhance humification and lead to longer-term reductions in N availability. Results indicated that, of the five carbon treatments, sugar, sawdust, and sawdust + sugar suppressed N availability, with sawdust + sugar being the most effective treatment to reduce N availability. The year after treatments stopped, N availability remained less in the sawdust + sugar treatment plots than in the high-N control plots. Three years after treatments ended, reductions in N availability were smaller (40-60%). Our results suggest that highly labile forms of carbon generate strong short-term N sinks, but these effects dissipate within one year of application, and that more recalcitrant forms reduce N longer. Sawdust + sugar was the most effective treatment to decrease exotic species canopy cover and increase native species density over the long term. Labile carbon had neither short- nor long-term effects on exotic species. Even though the organic amendments did not contribute to recovery of the dominant native species Bouteloua gracilis, they were effective in increasing another native species, Carex eleocharis. These results indicate that organic amendments may be a useful tool for restoring some native species in the shortgrass steppe, though not all. PMID:23734484

  10. Thermodynamic stability versus kinetic lability of ZnS4 core Delphine Picot, Gilles Ohanessian, Gilles Frison*

    E-print Network

    Paris-Sud XI, Université de

    1 Thermodynamic stability versus kinetic lability of ZnS4 core Delphine Picot, Gilles Ohanessian for Zn-S and Zn-N bond dissociation reactions in several Zn(SR)4 2­ and Zn(Im)(SR)3 ­ complexes. The Zn-S are metastable with respect to Zn-S and Zn-N bond dissociation respectively; this is consistent with the kinetic

  11. Labile rhizosphere soil solution fraction for prediction of bioavailability of heavy metals and rare earth elements to plants

    Microsoft Academic Search

    Xiao-quan Shan; Zhongwen Wang; Weisheng Wang; Shuzhen Zhang; Bei Wen

    2003-01-01

    A labile rhizosphere soil solution fraction has been recommended to predict the bioavailability of heavy metals and rare earth elements to plants. This method used moist rhizosphere soil in combination with a mixture of 0.01 mol L-1 of low-molecular-weight organic acids (LMWOAs) as extractant. The extracted soil solutions were fractionated into two colloidal fractions of wm (F3) and wm (F2),

  12. Monitoring of (bio)available labile metal fraction in a drinking water treatment plant by diffusive gradients in thin films

    Microsoft Academic Search

    Alfredo Díaz; Rebeca Arnedo; Raquel Céspedes-Sánchez; Ricard Devesa; Jordi Martin-Alonso

    A performance study of diffusive gradients in thin films (DGT) and inductively coupled plasma optical emission spectrometry\\u000a (ICP-OES) was applied for the monitoring of the labile fraction of metals Al, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn, in Sant\\u000a Joan Despí Drinking Water Treatment Plant located in the South of Barcelona’s Metropolitan Area (Spain). The DWTP monitoring

  13. Organic Food Production and Its Influence on Naturally Occurring Toxins

    Microsoft Academic Search

    Carl K. Winter

    The levels of natural plant toxins and mycotoxins in foods may be influenced by the methods used (organic vs. conventional)\\u000a for agricultural production. Research findings suggest that organic foods may possess higher levels of natural plant toxins\\u000a than conventional foods based upon mechanistic similarities between natural plant toxin production and the production of plant\\u000a secondary metabolites of nutritional interest. Specific

  14. Widespread presence of hydrophobic paralytic shellfish toxins in Gymnodinium catenatum

    Microsoft Academic Search

    Andrew P. Negri; Christopher J. S. Bolch; Stephanie Geier; David H. Green; Tae-Gyu Park; Susan I. Blackburn

    2007-01-01

    The toxic dinoflagellate Gymnodinium catenatum Graham produces a newly discovered sub-class of paralytic shellfish toxins (PSTs, saxitoxins) that contain a hydroxybenzoate moiety in place of the carbamoyl group (GC toxins: GC1–GC3). GC toxins bind strongly to sodium channels and their lipophilic nature may increase their potential to bioaccumulate in marine organisms. Cultures Australian G. catenatum strains were found to contain

  15. Contribution of Lethal Toxin and Edema Toxin to the Pathogenesis of Anthrax Meningitis ?

    PubMed Central

    Ebrahimi, Celia M.; Sheen, Tamsin R.; Renken, Christian W.; Gottlieb, Roberta A.; Doran, Kelly S.

    2011-01-01

    Bacillus anthracis is a Gram-positive spore-forming bacterium that causes anthrax disease in humans and animals. Systemic infection is characterized by septicemia, toxemia, and meningitis, the main neurological complication associated with high mortality. We have shown previously that B. anthracis Sterne is capable of blood-brain barrier (BBB) penetration, establishing the classic signs of meningitis, and that infection is dependent on the expression of both major anthrax toxins, lethal toxin (LT) and edema toxin (ET). Here we further investigate the contribution of the individual toxins to BBB disruption using isogenic toxin mutants deficient in lethal factor, ?LF, and edema factor, ?EF. Acute infection with B. anthracis Sterne and the ?LF mutant resulted in disruption of human brain microvascular endothelial cell (hBMEC) monolayer integrity and tight junction protein zona occludens-1, while the result for cells infected with the ?EF mutant was similar to that for the noninfected control. A significant decrease in bacterial invasion of BBB endothelium in vitro was observed during infection with the ?LF strain, suggesting a prominent role for LT in promoting BBB interaction. Further, treatment of hBMECs with purified LT or chemicals that mimic LT action on host signaling pathways rescued the hypoinvasive phenotype of the ?LF mutant and resulted in increased bacterial uptake. We also observed that toxin expression reduced bacterial intracellular survival by inducing the bulk degradative autophagy pathway in host cells. Finally, in a murine model of anthrax meningitis, mice infected with the ?LF mutant exhibited no mortality, brain bacterial load, or evidence of meningitis compared to mice infected with the parental or ?EF strains. PMID:21518787

  16. Clostridium perfringens Epsilon Toxin Causes Selective Death of Mature Oligodendrocytes and Central Nervous System Demyelination

    PubMed Central

    Linden, Jennifer R.; Ma, Yinghua; Zhao, Baohua; Harris, Jason Michael; Rumah, Kareem Rashid; Schaeren-Wiemers, Nicole

    2015-01-01

    ABSTRACT Clostridium perfringens epsilon toxin (?-toxin) is responsible for a devastating multifocal central nervous system (CNS) white matter disease in ruminant animals. The mechanism by which ?-toxin causes white matter damage is poorly understood. In this study, we sought to determine the molecular and cellular mechanisms by which ?-toxin causes pathological changes to white matter. In primary CNS cultures, ?-toxin binds to and kills oligodendrocytes but not astrocytes, microglia, or neurons. In cerebellar organotypic culture, ?-toxin induces demyelination, which occurs in a time- and dose-dependent manner, while preserving neurons, astrocytes, and microglia. ?-Toxin specificity for oligodendrocytes was confirmed using enriched glial culture. Sensitivity to ?-toxin is developmentally regulated, as only mature oligodendrocytes are susceptible to ?-toxin; oligodendrocyte progenitor cells are not. ?-Toxin sensitivity is also dependent on oligodendrocyte expression of the proteolipid myelin and lymphocyte protein (MAL), as MAL-deficient oligodendrocytes are insensitive to ?-toxin. In addition, ?-toxin binding to white matter follows the spatial and temporal pattern of MAL expression. A neutralizing antibody against ?-toxin inhibits oligodendrocyte death and demyelination. This study provides several novel insights into the action of ?-toxin in the CNS. (i) ?-Toxin causes selective oligodendrocyte death while preserving all other neural elements. (ii) ?-Toxin-mediated oligodendrocyte death is a cell autonomous effect. (iii) The effects of ?-toxin on the oligodendrocyte lineage are restricted to mature oligodendrocytes. (iv) Expression of the developmentally regulated proteolipid MAL is required for the cytotoxic effects. (v) The cytotoxic effects of ?-toxin can be abrogated by an ?-toxin neutralizing antibody. PMID:26081637

  17. Molecular Imaging of Labile Iron(II) Pools in Living Cells with a Turn-On Fluorescent Probe

    PubMed Central

    Au-Yeung, Ho Yu; Chan, Jefferson; Chantarojsiri, Teera; Chang, Christopher J.

    2013-01-01

    Iron is an essential metal for living organisms, but misregulation of its homeostasis at the cellular level can trigger detrimental oxidative and/or nitrosative stress and damage events. Motivated to help study the physiological and pathological consequences of biological iron regulation, we now report a reaction-based strategy for monitoring labile Fe2+ pools in aqueous solution and in living cells. Iron Probe 1 (IP1) exploits a bioinspired, iron-mediated oxidative C–O bond cleavage reaction to achieve a selective turn-on response to Fe2+ over a range of cellular metal ions in their bioavailable forms. We show that this first-generation chemical tool for fluorescence Fe2+ detection can visualize changes in exchangeable iron stores in living cells upon iron supplementation or depletion, including labile iron pools at endogenous, basal levels. Moreover, IP1 can be used to identify reversible expansion of labile iron pools by stimulation with vitamin C or the iron regulatory hormone hepcidin, providing a starting point for further investigations of iron signaling and stress events in living systems as well as future probe development. PMID:24063668

  18. A school-based expressive writing intervention for at-risk urban adolescents' aggressive behavior and emotional lability.

    PubMed

    Kliewer, Wendy; Lepore, Stephen J; Farrell, Albert D; Allison, Kevin W; Meyer, Aleta L; Sullivan, Terri N; Greene, Anne Y

    2011-01-01

    This school-based randomized controlled trial tested the efficacy of 2 expressive writing interventions among youth living in high-violence urban neighborhoods. Seventeen classrooms (n = 258 seventh graders; 55% female; 91% African American/Black) from 3 public schools were randomized to 3 conditions in which they wrote 8 times about a nonemotional topic (control condition) or about experiencing and witnessing violence following either a standard or an enhanced expressive writing protocol. Outcomes were assessed 1 month prior and 2 and 6 months postintervention and included teacher-rated emotional lability and aggressive behavior and child-rated physical aggression. Intent-to-treat, mixed-model analyses controlled for preintervention measures of outcomes, sex, race, and family structure. At 2 months postintervention, relative to controls, students in the standard expressive writing condition had lower levels of teacher-rated aggression and lability (d = -.48). The beneficial effects of the writing interventions on aggression and lability were stronger at higher levels of community violence exposure. PMID:21916688

  19. Suppression of inflammation in a mouse model of rheumatoid arthritis using targeted lipase-labile fumagillin prodrug nanoparticles

    PubMed Central

    Zhou, Hui-fang; Yan, Huimin; Senpan, Angana; Wickline, Samuel A.; Pan, Dipanjan; Lanza, Gregory M.; Pham, Christine T.N.

    2013-01-01

    Nanoparticle-based therapeutics are emerging technologies that have the potential to greatly impact the treatment of many human diseases. However, drug instability and premature release from the nanoparticles during circulation currently preclude clinical translation. Herein, we use a lipase-labile (Sn 2) fumagillin prodrug platform coupled with a unique lipid surface-to-surface targeted delivery mechanism, termed contact-facilitated drug delivery, to counter the premature drug release and overcome the inherent photo-instability of fumagillin, an established anti-angiogenic agent. We show that ?v?3-integrin targeted fumagillin prodrug nanoparticles, administered at 0.3 mg of fumagillin prodrug/kg of body weight suppress the clinical disease indices of KRN serum-mediated arthritis in a dose-dependent manner when compared to treatment with the control nanoparticles with no drug. This study demonstrates the effectiveness of this lipase-labile prodrug nanocarrier in a relevant preclinical model that approximates human rheumatoid arthritis. The lipase-labile prodrug paradigm offers a translatable approach that is broadly applicable to many targeted nanosystems and increases the translational potential of this platform for many diseases. PMID:22922023

  20. Inhibition of insulin-stimulated glucose transport in 3T3-L1 cells by Clostridium difficile toxin B, Clostridium sordellii lethal toxin, and Clostridium botulinum C2 toxin

    Microsoft Academic Search

    Gudrun Schmid; Annette Schürmann; Christine Huppertz; Fred Hofmann; Klaus Aktories; Hans-Georg Joost

    1998-01-01

    The role of the actin cytoskeleton and\\/or GTPases of the Rho\\/Rac-family in glucose transport regulation was investigated in\\u000a 3T3-L1 cells with clostridial toxins which depolymerize actin by inactivation of Rho\\/Rac (Clostridium difficile toxin B and Clostridium sordellii lethal toxin (LT)) or by direct ADP-ribosylation (Clostridium botulinum C2 toxin). Toxin B and C2 reduced insulin-stimulated, but not basal, 2-deoxyglucose (2-DOG) uptake

  1. Contributions to the bioassay of Gymnodinium breve toxin(s) with mosquito fish (Gambusia affinis 

    E-print Network

    Russell, Melvin Curtis

    1972-01-01

    solvents. See Figures 6-10 for dose response data 36 Mean death times of fish exposed to two con- t t' f d G~dt ' d t ' \\ 0. 06%%d polysorbate 80 (tween 80) solution to pro- vide reference points for tests with five solvent- toxin concentrations... to assay G. breve toxin (personal communication) . ~Gd' ' b t ' ' ' *l bl * ly l'glltly l bl* water, but soluble in lipid solvents. For intraperitoneal injection of mice, Spikes et al. (13, 16) used polysorbate 80 (tween 80) as an emulsifying agent...

  2. Visualization of Peroxynitrite-Induced Changes of Labile Zn[superscript 2+] in the Endoplasmic Reticulum with Benzoresorufin-based Fluorescent Probes

    E-print Network

    Lin, Wei

    Zn[superscript 2+] plays essential roles in biology, and the homeostasis of Zn[superscript 2+] is tightly regulated in all cells. Subcellular distribution and trafficking of labile Zn[superscript 2+], and its inter-relation ...

  3. 9 CFR 121.4 - Overlap select agents and toxins.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ...products. (b) Overlap select agents and toxins: Bacillus anthracis; Brucella abortus; Brucella melitensis...24 hours by telephone, facsimile, or e-mail: Bacillus anthracis, Brucella melitensis, Hendra virus,...

  4. 9 CFR 121.4 - Overlap select agents and toxins.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... (b) Overlap select agents and toxins: *Bacillus anthracis; Bacillus anthracis (Pasteur strain); Brucella abortus...hours by telephone, facsimile, or e-mail: Bacillus anthracis, Burkholderia mallei, and...

  5. 9 CFR 121.4 - Overlap select agents and toxins.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... (b) Overlap select agents and toxins: *Bacillus anthracis; Bacillus anthracis (Pasteur strain); Brucella abortus...hours by telephone, facsimile, or e-mail: Bacillus anthracis, Burkholderia mallei, and...

  6. Computational Studies of Marine Toxins Targeting Ion Channels

    PubMed Central

    Rashid, M. Harunur; Mahdavi, Somayeh; Kuyucak, Serdar

    2013-01-01

    Toxins from marine animals offer novel drug leads for treatment of diseases involving ion channels. Computational methods could be very helpful in this endeavour in several ways, e.g., (i) constructing accurate models of the channel-toxin complexes using docking and molecular dynamics (MD) simulations; (ii) determining the binding free energies of toxins from umbrella sampling MD simulations; (iii) predicting the effect of mutations from free energy MD simulations. Using these methods, one can design new analogs of toxins with improved affinity and selectivity properties. Here we present a review of the computational methods and discuss their applications to marine toxins targeting potassium and sodium channels. Detailed examples from the potassium channel toxins—ShK from sea anemone and ?-conotoxin PVIIA—are provided to demonstrate capabilities of the computational methods to give accurate descriptions of the channel-toxin complexes and the energetics of their binding. An example is also given from sodium channel toxins (µ-conotoxin GIIIA) to illustrate the differences between the toxin binding modes in potassium and sodium channels. PMID:23528952

  7. Fusarial toxins: secondary metabolites of Fusarium fungi.

    PubMed

    Nesic, Ksenija; Ivanovic, Snezana; Nesic, Vladimir

    2014-01-01

    Exposure to mycotoxins occurs worldwide, even though there are geographic and climatic differences in the amounts produced and occurrence of these substances.Mycotoxins are secondary chemical metabolites of different fungi. They are natural contaminants of cereals, so their presence is often inevitable. Among many genera that produce mycotoxins, Fusarium fungi are the most widespread in cereal-growing areas of the planet. Fusarium fungi produce a diversity of mycotoxin types, whose distributions are also diverse. What is produced and where it is produced is influenced primarily by environmental conditions, and crop production and storage methods. The amount of toxin produced depends on physical (viz., moisture, relative humidity, temperature, and mechanical damage), chemical (viz., carbon dioxide,oxygen, composition of substrate, insecticides and fungicides), and biological factors (viz., plant variety, stress, insects, spore load, etc.). Moisture and temperature have a major influence on mold growth rate and mycotoxin production.Among the most toxic and prevalent fusaria) toxins are the following: zearalenone,fumonisins, moniliformin and trichothecenes (T-2/HT-2 toxin, deoxynivalenol,diacetoxyscirpenol, nivalenol). Zearalenone (ZEA; ZON, F-2 toxin) isaphy to estrogenic compound, primarily a field contaminant, which exhibits estrogenic activity and has been implicated in numerous mycotoxicoses of farm animals,especially pigs. Recently, evidence suggests that ZEA has potential to stimulate the growth of human breast cancer cells. Fumonisins are also cancer-promoting metabolites,of which Fumonisin 8 I (FBI) is the most important. Moniliformin (MON) isalso highly toxic to both animals and humans. Trichothecenes are classified as gastrointestinal toxins, dermatotoxins, immunotoxins, hematotoxins, and gene toxins.T-2 and HT-2 toxin, and diacetoxyscirpenol (DAS, anguidine) are the most toxic mycotoxins among the trichothecene group. Deoxynivalenol (DON, vomitoxin) and nivalenol although less toxic are important because they frequently occur at levels high enough to cause adverse effects.The presence of mycotoxins in the animal diet can produce significant production losses. Any considerable presence of mycotoxins, in major dietary components,confirms the need to adopt a continuous prevention and control program. Such programs are usually based on several common approaches to minimize mycotoxin contamination in the food chain. Major strategies include preventing fungal growth and therefore mycotoxin formation, reducing or eliminating mycotoxins from contaminated feedstuffs, or diverting contaminated products to low risk uses. Because of the complexity of their chemical structures, mycotoxins also present a major analytical challenge. They are also found in a vast array of feed matrices. Analysis is essential for determining the extent of mycotoxin contamination, for risk analysis, confirming the diagnosis of a mycotoxicosis and for monitoring mycotoxin mitigation strategies.For the future, adequately controlling the mycotoxin problem in the livestock economy will depend on implementing appropriate agricultural management policies,as well as augmenting production and storage systems and analysis methods.Only such policies offer the opportunity to bring solid and long-lasting economical results to the livestock industry that is afflicted with the mycotoxin problem. PMID:24162094

  8. Mtx toxins from Lysinibacillus sphaericus enhance mosquitocidal cry-toxin activity and suppress cry-resistance in Culex quinquefasciatus.

    PubMed

    Wirth, Margaret C; Berry, Colin; Walton, William E; Federici, Brian A

    2014-01-01

    The interaction of Mtx toxins from Lysinibacillus sphaericus (formerly Bacillus sphaericus) with Bacillus thuringiensis subsp. israelensis Cry toxins and the influence of such interactions on Cry-resistance were evaluated in susceptible and Cry-resistant Culex quinquefasciatus larvae. Mtx-1 and Mtx-2 were observed to be active against both susceptible and resistant mosquitoes; however varying levels of cross-resistance toward Mtx toxins were observed in the resistant mosquitoes. A 1:1 mixture of either Mtx-1 or Mtx-2 with different Cry toxins generally showed moderate synergism, but some combinations were highly toxic to resistant larvae and suppressed resistance. Toxin synergy has been demonstrated to be a powerful tool for enhancing activity and managing Cry-resistance in mosquitoes, thus Mtx toxins may be useful as components of engineered bacterial larvicides. PMID:24144574

  9. Cross-Reactivity of Anthrax and C2 Toxin: Protective Antigen Promotes the Uptake of Botulinum C2I Toxin into Human Endothelial Cells

    Microsoft Academic Search

    Angelika Kronhardt; Monica Rolando; Christoph Beitzinger; Caroline Stefani; Michael Leuber; Gilles Flatau; Michel R. Popoff; Roland Benz; Emmanuel Lemichez

    2011-01-01

    Binary toxins are among the most potent bacterial protein toxins performing a cooperative mode of translocation and exhibit fatal enzymatic activities in eukaryotic cells. Anthrax and C2 toxin are the most prominent examples for the AB7\\/8 type of toxins. The B subunits bind both host cell receptors and the enzymatic A polypeptides to trigger their internalization and translocation into the

  10. A dual colorimetric-ratiometric fluorescent probe NAP-3 for selective detection and imaging of endogenous labile iron(III) pools in C. elegans.

    PubMed

    Goel, Atul; Umar, Shahida; Nag, Pankaj; Sharma, Ashutosh; Kumar, Lalit; Shamsuzzama; Hossain, Zakir; Gayen, Jiaur R; Nazir, Aamir

    2015-03-25

    The discovery of an iron(III)-selective ratiometric fluorescent probe to detect and visualize endogenous labile iron pools in living organisms at the molecular level has been long awaited. Herein we report the first dual colorimetric and ratiometric fluorescent probe naphtho[2,1-b][1,10]phenanthroline for selective and 'direct' visualization of labile iron(III) pools in a multicellular organism, Caenorhabditis elegans. PMID:25633904

  11. Polypharmacology profiles and phylogenetic analysis of three-finger toxins from mamba venom: case of aminergic toxins.

    PubMed

    Blanchet, Guillaume; Collet, Guillaume; Mourier, Gilles; Gilles, Nicolas; Fruchart-Gaillard, Carole; Marcon, Elodie; Servent, Denis

    2014-08-01

    Composition of mamba's venom is quite atypical and characterized by the presence of a large diversity of three-finger fold toxins (3FTx) interacting with various enzymes, receptors and ion channels. In particular, 3FTx from mambas display the unique property to interact with class A GPCRs, sometimes with a high affinity and selectivity. A screening of five of these toxins (MT1, MT3, MT7, ?-Da1a and ?-Da1b) on 29 different subtypes of bioaminergic receptors, using competition binding experiments, highlights the diversity of their pharmacological profiles. These toxins may display either absolute selectivity for one receptor subtype or a polypharmacological property for various bioaminergic receptors. Nevertheless, adrenoceptor is the main receptor family targeted by these toxins. Furthermore, a new receptor target was identified for 3FTx and toxins in general, the ?-Da1b interacting competitively with the human dopamine D3 receptor in the micromolar range. This result expands the diversity of GPCRs targeted by toxins and more generally highlights the multipotent interacting property of 3FTx. Phylogenic analyzes of these toxins show that muscarinic, adrenergic and dopaminergic toxins may be pooled in one family called aminergic toxins, this family coming probably from a specific radiation of ligands present in mamba venoms. PMID:24793485

  12. The influence of labile dietary methyl donors on the arginine requirement of young broiler chicks.

    PubMed

    Chamruspollert, M; Pesti, G M; Bakalli, R I

    2002-08-01

    Two experiments were conducted with Ross x Ross boiler chicks in battery brooders from 1 to 14 d of age to determine the influence of dietary methyl donors on the Arg requirement of young broiler chicks. Experiment 1 had a 6 x 2 factorial design, with six levels of Arg supplementation (0, 0.1, 0.2, 0.3, 0.4, and 0.5%) and two levels of DL-Met supplementation (0 and 0.2% of the diet). The design of Experiment 2 was identical to Experiment 1, except that a second source of labile methyl groups was added, 0.2% betaine (6 x 3 factorial arrangement). Both experiments had four replicate pens of 10 chicks each per treatment. The basal diet was based on corn (34.52%), whey (26.96%), corn gluten meal (16.53%), soybean meal (11.74%), and poultry fat (23% CP and 3.20 kcal/g of ME). At 14 d, three chicks per replicate were randomly killed, and breast muscle was collected and pooled for creatine analysis. The broken-line linear model was used to estimate the Arg requirements of the chicks. There were no differences in Arg requirements due to methyl source so the data were pooled. In Experiment 1, the Arg requirements were 1.17 +/- 0.04% for gain, 1.23 +/- 0.03% for feed conversion ratio (FCR), and 1.18 +/- 0.03% for muscle creatine, when the diet contained 0.45 or 0.65% Met. In Experiment 2, the Arg requirements were 1.20 +/- 0.05% for gain, 1.23 +/- 0.03% for FCR, and 1.26 +/- 0.02% for muscle creatine. There was no apparent difference in the Arg requirement of young broilers due to methyl donor supplementation. PMID:12211306

  13. Detection of Labile Low-Molecular-Mass Transition Metal Complexes in Mitochondria.

    PubMed

    McCormick, Sean P; Moore, Michael J; Lindahl, Paul A

    2015-06-01

    Liquid chromatography was used with an online inductively coupled plasma mass spectrometer to detect low-molecular-mass (LMM) transition metal complexes in mitochondria isolated from fermenting yeast cells, human Jurkat cells, and mouse brain and liver. These complexes constituted 20-40% of total mitochondrial Mn, Fe, Zn, and Cu ions. The major LMM Mn complex in yeast mitochondria, called Mn1100, had a mass of ?1100 Da and a concentration of ?2 ?M. Mammalian mitochondria contained a second Mn species with a mass of ?2000 Da at a comparable concentration. The major Fe complex in mitochondria isolated from exponentially growing yeast cells had a mass of ?580 Da; the concentration of Fe580 in mitochondria was ?100 ?M. When mitochondria were isolated from fermenting cells in postexponential phase, the mass of the dominant LMM Fe complex was ?1100 Da. Upon incubation, the intensity of Fe1100 declined and that of Fe580 increased, suggesting that the two are interrelated. Mammalian mitochondria contained Fe580 and two other Fe species (Fe2000 and Fe1100) at concentrations of ?50 ?M each. The dominant LMM Zn species in mitochondria had a mass of ?1200 Da and a concentration of ?110 ?M. Mammalian mitochondria contained a second major LMM Zn species at 1500 Da. The dominant LMM Cu species in yeast mitochondria had a mass of ?5000 Da and a concentration in yeast mitochondria of ?16 ?M; Cu5000 was not observed in mammalian mitochondria. The dominant Co species in mitochondria, Co1200, had a concentration of 20 nM and was probably a cobalamin. Mammalian but not yeast mitochondria contained a LMM Mo species, Mo730, at a concentration of ?1 ?M. Increasing Mn, Fe, Cu, and Zn concentrations 10-fold in the medium increased the concentration of the same element in the corresponding isolated mitochondria. Treatment with metal chelators confirmed that these LMM species were labile. The dominant S species at 1100 Da was not free glutathione or glutathione disulfide. PMID:26018429

  14. Analysis of efficacy of CVD 103-HgR live oral cholera vaccine against all-cause travellers’ diarrhoea in a randomised, double-blind, placebo-controlled study

    Microsoft Academic Search

    E. M. S. Leyten; D. Soonawala; C. Schultsz; C. Herzog; R. J. Ligthelm; S. Wijnands; L. G. Visser

    2005-01-01

    Enterotoxigenic Escherichia coli (ETEC), which produces heat labile toxin (LT) and\\/or heat stable toxin (ST), is considered to be the most common known cause of travellers’ diarrhoea (TD). Owing to the antigenic similarity between cholera toxin and LT, immunization with inactivated oral B-subunit\\/whole-cell cholera vaccine (BS–WC) offers short term (3 months) but significant (>67%) protection against TD caused by LT-related

  15. Isolation of the toxin in Daubentonia longifolia 

    E-print Network

    Robey, Ashley

    1925-01-01

    THE ISOLATION OF THE TOXIN IN DAUBENTONIA LONGIFOLIA A THESIS SUBMITTED TO THE FACULTY OF THE AGRICULTURAL AND MECHANICAL COLLEGE OF TEXAS IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE BY ASHLEY ROBEY&B. S... uneasinons, the animal lying d. own and getting up frequently until too weak to do so. Fre- quent belching, also a green frothy discharge from the mouth. Dilation of the pupils, after;"hich the sheep became semi-oomatose, bleatin freauently un- til death...

  16. Protective immunity to ricin toxin conferred by antibodies against the toxin's binding subunit (RTB).

    PubMed

    Yermakova, Anastasiya; Mantis, Nicholas J

    2011-10-19

    The B subunit (RTB) of ricin toxin is a galactose-/N-acetyl galactosamine-specific lectin that promotes attachment and entry of ricin into host cells. RTB is also the archetype of the so-called R-type lectin family, whose members include haemagglutinins of botulinum neurotoxin (BoNT) progenitor toxins, as well as the binding subunits of cytolethal distending toxins. Although RTB is an appealing subunit vaccine candidate, as well as a potential target for immunotherapeutics, the degree to which RTB immunization elicits protective antibodies against ricin toxin remains unresolved. To address this issue, groups of mice were immunized with RTB and then challenged with 5×LD(50)s of ricin administered intraperitoneally. Despite high RTB-specific serum antibody titers, groups of RTB immunized mice were only partially immune to ricin challenge. Analysis of a collection of RTB-specific B cell hybridomas suggested that only a small fraction of antibodies against RTB have demonstrable neutralizing activity. Two RTB-specific neutralizing monoclonal IgG(1) antibodies, 24B11 and SylH3, when passively administered to mice, were sufficient to protect the animals against a 5×LD(50) dose of ricin. Both 24B11 and SylH3 blocked ricin attachment to terminal galactose residues and prevented toxin binding to the surfaces of bone marrow-derived macrophages (BMM), suggesting that they function by steric hindrance and recognize epitopes located on RTB's carbohydrate recognition sub-domains (1? or 2?). These data raise the possibility of using specific RTB sub-domains, rather than RTB itself, as antigens to more efficiently elicit neutralizing antibodies and protective immunity against ricin. PMID:21872634

  17. Multiplex detection of protein toxins using MALDI-TOF-TOF tandem mass spectrometry: application in unambiguous toxin detection from bioaerosol.

    PubMed

    Alam, Syed Imteyaz; Kumar, Bhoj; Kamboj, Dev Vrat

    2012-12-01

    Protein toxins, such as botulinum neurotoxins (BoNTs), Clostridium perfringens epsilon toxin (ETX), staphylococcal enterotoxin B (SEB), shiga toxin (STX), and plant toxin ricin, are involved in a number of diseases and are considered as potential agents for bioterrorism and warfare. From a bioterrorism and warfare perspective, these agents are likely to cause maximum damage to a civilian or military population through an inhalational route of exposure and aerosol is considered the envisaged mode of delivery. Unambiguous detection of toxin from aerosol is of paramount importance, both for bringing mitigation protocols into operation and for implementation of effective medical countermeasures, in case a "biological cloud" is seen over a population. A multiplex, unambiguous, and qualitative detection of protein toxins is reported here using tandem mass spectrometry with MALDI-TOF-TOF. The methodology involving simple sample processing steps was demonstrated to identify toxins (ETX, Clostridium perfringes phospholipase C, and SEB) from blind spiked samples. The novel directed search approach using a list of unique peptides was used to identify toxins from a complex protein mixture. The bioinformatic analysis of seven protein toxins for elucidation of unique peptides with conservation status across all known sequences provides a high confidence for detecting toxins originating from any geographical location and source organism. Use of tandem MS data with peptide sequence information increases the specificity of the method. A prototype for generation of aerosol using a nebulizer and collection using a cyclone collector was used to provide a proof of concept for unambiguous detection of toxin from aerosol using precursor directed tandem mass spectrometry combined with protein database searching. ETX prototoxin could be detected from aerosol at 0.2 ppb concentration in aerosol. PMID:23083074

  18. THE CONTRIBUTION OF CYTOLETHAL DISTENDING TOXIN TO BACTERIAL PATHOGENESIS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cytolethal distending toxin (CDT) is a bacterial toxin that initiates a eukaryotic cell cycle block at the G2 stage prior to mitosis. CDT is produced by a number of bacterial pathogens including: Campylobacter species, Escherichia coli, Salmonella enterica serovar Typhi, Shigella dystenteriae, ente...

  19. The common bacterial toxins hypothesis of sudden infant death syndrome

    Microsoft Academic Search

    James A Morris

    1999-01-01

    The background to the common bacterial toxin hypothesis of sudden infant death syndrome is presented. The idea is that some cases of sudden infant death syndrome are due to the lethal effects of nasopharyngeal bacterial toxins which can act synergistically to trigger the events leading to death. The concept is consistent with the age distribution of sudden infant death syndrome,

  20. Multiple receptors as targets of Cry toxins in mosquitoes.

    PubMed

    Likitvivatanavong, Supaporn; Chen, Jianwu; Evans, Amy M; Bravo, Alejandra; Soberon, Mario; Gill, Sarjeet S

    2011-04-13

    Bacillus thuringiensis (Bt) produces inclusions that are composed of proteins known as crystal proteins or Cry toxins. Due to their high specificity and their safety to humans and the environment, these Cry toxins are considered to be valuable alternatives to chemical pesticides in insect control programs. It is believed that Cry toxin-induced membrane pore formation is responsible for insect toxicity. The molecular mechanism of pore formation involves recognition and subsequent binding of the toxin to membrane receptors. This binding is accompanied by toxin oligomerization and transfer of domain I helices of the toxin to the lipid-water interface. This toxin insertion creates pores that lyse the cells. Several receptors from lepidopteran, coleopteran, and dipteran insects have been well characterized. This paper provides an overview of the understanding of the interactions between Cry toxin and multiple receptors in mosquitoes, in particular Aedes aegypti and reviews the manner by which the receptors were identified and characterized, with a focus on three proteins, cadherin, alkaline phosphatase, and aminopeptidase-N. PMID:21210704

  1. Shiga toxins and stx phages: highly diverse entities.

    PubMed

    Krüger, Alejandra; Lucchesi, Paula M A

    2015-03-01

    Shiga toxins are the main virulence factors of a group of Escherichia coli strains [Shiga toxin-producing E. coli (STEC)] that cause severe human diseases, such as haemorrhagic colitis and haemolytic-uraemic syndrome. The Shiga toxin family comprises several toxin subtypes, which have been differentially related to clinical manifestations. In addition, the phages that carry the Shiga toxin genes (stx phages) are also diverse. These phages play an important role not only in the dissemination of Shiga toxin genes and the emergence of new STEC strains, but also in the regulation of Shiga toxin production. Consequently, differences in stx phages may affect the dissemination of stx genes as well as the virulence of STEC strains. In addition to presenting an overview of Shiga toxins and stx phages, in this review we highlight current knowledge about the diversity of stx phages, with emphasis on its impact on STEC virulence. We consider that this diversity should be taken into account when developing STEC infection treatments and diagnostic approaches, and when conducting STEC control in reservoirs. PMID:25479836

  2. EFFECTS OF SHIGA TOXIN ON ISOLATED PORCINE GRANULOCYTES

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Background: Shiga toxin (Stx) binding to polymorphonuclear leukocytes (PMN) is hypothesized to play a role in the pathogenesis of Shiga toxin-producing Escherichia coli (STEC) disease in humans. Pigs are an excellent model for studying the role of PMN in STEC disease because, like humans, they are ...

  3. de novo Synthesis of a Bacterial Toxin/ Antitoxin System

    E-print Network

    Wood, Thomas K.

    of toxin/antitoxin (TA) systems in Archaea1 and Bacteria2 appears to be counterintuitive given-mediated reduced growth is therefore beneficial for bacteria for surviving antibiotic stress6­8 and for combating, the IetS toxin is highly similar to subtilisin- like serine proteases while the IetA antitoxin is similar

  4. Structural interactions of a voltage sensor toxin with lipid membranes

    PubMed Central

    Mihailescu, Mihaela; Krepkiy, Dmitriy; Milescu, Mirela; Gawrisch, Klaus; Swartz, Kenton J.; White, Stephen

    2014-01-01

    Protein toxins from tarantula venom alter the activity of diverse ion channel proteins, including voltage, stretch, and ligand-activated cation channels. Although tarantula toxins have been shown to partition into membranes, and the membrane is thought to play an important role in their activity, the structural interactions between these toxins and lipid membranes are poorly understood. Here, we use solid-state NMR and neutron diffraction to investigate the interactions between a voltage sensor toxin (VSTx1) and lipid membranes, with the goal of localizing the toxin in the membrane and determining its influence on membrane structure. Our results demonstrate that VSTx1 localizes to the headgroup region of lipid membranes and produces a thinning of the bilayer. The toxin orients such that many basic residues are in the aqueous phase, all three Trp residues adopt interfacial positions, and several hydrophobic residues are within the membrane interior. One remarkable feature of this preferred orientation is that the surface of the toxin that mediates binding to voltage sensors is ideally positioned within the lipid bilayer to favor complex formation between the toxin and the voltage sensor. PMID:25453087

  5. Nano Aptasensor for Protective Antigen Toxin of Lakshmi N. Cella,,,|

    E-print Network

    Chen, Wilfred

    Nano Aptasensor for Protective Antigen Toxin of Anthrax Lakshmi N. Cella,,,| Pablo Sanchez of California, Riverside, California 92521 We demonstrate a highly sensitive nano aptasensor for anthrax toxin, demonstrating it as a potential tool for rapid and point-of-care diagnosis for anthrax. Anthrax is a disease

  6. EFFECT OF MARINE TOXINS ON THERMOREGULATION IN MICE.

    EPA Science Inventory

    Marine algal toxins are extremely toxic and can represent a major health problem to humans and animals. Temperature regulation is one of many processes to be affected by exposure to these toxins. Mice and rats become markedly hypothermic when subjected to acute exposure to the ma...

  7. Sensitive detection of multiplex toxins using antibody microarray.

    PubMed

    Lian, Wei; Wu, Donghai; Lim, Daniel V; Jin, Shouguang

    2010-06-15

    Using a newly developed fluorescent nanoparticle (NP) that gives rise to a high-intensity and stable fluorescent light, a sensitive antibody (Ab) microarray assay system has been developed for specific detection of bioterrorism agents, as exemplified by ricin, cholera toxin (CT), and staphylococcal enterotoxin B (SEB). The Ab microarray uses a sandwich format that consists of capture Abs, analytes (toxins), biotinylated detection Abs, and avidin-conjugated NP. In all three cases, polyclonal Abs (pAbs) displayed superiority over monoclonal antibodies (mAbs) in capturing toxins on microarray slides even when the pAbs and mAbs had similar affinity as determined by enzyme-linked immunosorbent assay (ELISA). The detection system was successfully used to detect toxins spiked in milk, apple cider, and blood samples. We were able to detect ricin at 100 pg/ml in buffer and at 1 ng/ml in spiked apple cider or milk, whereas CT and SEB were detected at 10 pg/ml in buffer and 100 pg/ml in spiked apple cider or milk. High specificities were also demonstrated in the detection of mixed toxin samples with similar sensitivities. The matrix effect of blood samples on the detection of mixed toxins seems to be minimal when the toxin concentration is at or above 100 ng/ml. The current study highlights the significant role of pAb and NP in increasing selectivity and sensitivity of toxin detection in a microarray format. PMID:20226158

  8. Lysogenic Conversion by a Filamentous Phage Encoding Cholera Toxin

    Microsoft Academic Search

    Matthew K. Waldor; John J. Mekalanos

    1996-01-01

    Vibrio cholerae, the causative agent of cholera, requires two coordinately regulated factors for full virulence: cholera toxin (CT), a potent enterotoxin, and toxin-coregulated pili (TCP), surface organelles required for intestinal colonization. The structural genes for CT are shown here to be encoded by a filamentous bacteriophage (designated CTXPhi), which is related to coliphage M13. The CTXPhi genome chromosomally integrated or

  9. Cholera toxin stimulation of human mammary epithelial cells in culture

    SciTech Connect

    Stampfer, M.R.

    1982-06-01

    Addition of cholera toxin to human mammary epithelial cultures derived from reduction mammoplasties and primary carcinomas greatly stimulated cell growth and increased the number of times the cells could be successfully subcultured. Other agents known to increase intracellular cAMP levels were also growth stimulatory. The increased growth potential conferred by cholera toxin enhances the usefulness of this cell culture system.

  10. ClanTox: a classifier of short animal toxins

    Microsoft Academic Search

    Guy Naamati; Manor Askenazi; Michal Linial

    2009-01-01

    Toxins are detected in sporadic species along the evolutionary tree of the animal kingdom. Venomous animals include scorpions, snakes, bees, wasps, frogs and numerous animals living in the sea such as the stonefish, snail, jellyfish, hydra and more. Interestingly, proteins that share a common scaffold with animal toxins also exist in non-venomous spe- cies. However, due to their short length

  11. ClanTox: a classifier of short animal toxins.

    PubMed

    Naamati, Guy; Askenazi, Manor; Linial, Michal

    2009-07-01

    Toxins are detected in sporadic species along the evolutionary tree of the animal kingdom. Venomous animals include scorpions, snakes, bees, wasps, frogs and numerous animals living in the sea such as the stonefish, snail, jellyfish, hydra and more. Interestingly, proteins that share a common scaffold with animal toxins also exist in non-venomous species. However, due to their short length and primary sequence diversity, these, toxin-like proteins remain undetected by classical search engines and genome annotation tools. We construct a toxin classification machine and web server called ClanTox (Classifier of Animal Toxins) that is based on the extraction of sequence-driven features from the primary protein sequence followed by the application of a classification system trained on known animal toxins. For a given input list of sequences, from venomous or non-venomous settings, the ClanTox system predicts whether each sequence is toxin-like. ClanTox provides a ranked list of positively predicted candidates according to statistical confidence. For each protein, additional information is presented including the presence of a signal peptide, the number of cysteine residues and the associated functional annotations. ClanTox is a discovery-prediction tool for a relatively overlooked niche of toxin-like cell modulators, many of which are therapeutic agent candidates. The ClanTox web server is freely accessible at http://www.clantox.cs.huji.ac.il. PMID:19429697

  12. ClanTox: a classifier of short animal toxins

    PubMed Central

    Naamati, Guy; Askenazi, Manor; Linial, Michal

    2009-01-01

    Toxins are detected in sporadic species along the evolutionary tree of the animal kingdom. Venomous animals include scorpions, snakes, bees, wasps, frogs and numerous animals living in the sea such as the stonefish, snail, jellyfish, hydra and more. Interestingly, proteins that share a common scaffold with animal toxins also exist in non-venomous species. However, due to their short length and primary sequence diversity, these, toxin-like proteins remain undetected by classical search engines and genome annotation tools. We construct a toxin classification machine and web server called ClanTox (Classifier of Animal Toxins) that is based on the extraction of sequence-driven features from the primary protein sequence followed by the application of a classification system trained on known animal toxins. For a given input list of sequences, from venomous or non-venomous settings, the ClanTox system predicts whether each sequence is toxin-like. ClanTox provides a ranked list of positively predicted candidates according to statistical confidence. For each protein, additional information is presented including the presence of a signal peptide, the number of cysteine residues and the associated functional annotations. ClanTox is a discovery-prediction tool for a relatively overlooked niche of toxin-like cell modulators, many of which are therapeutic agent candidates. The ClanTox web server is freely accessible at http://www.clantox.cs.huji.ac.il. PMID:19429697

  13. Crystallographic studies of the Anthrax lethal toxin. Annual report

    Microsoft Academic Search

    1996-01-01

    The lethal form of Anthrax results from the inhalation of anthrax spores. Death is primarily due to the effects of the lethal toxin (Protective Antigen (PA) + Lethal Factor) from the causative agent, Bacillus anthracis. All the Anthrax vaccines currently in use or under development contain or produce PA, the major antigenic component of anthrax toxin, and there is a

  14. An alternative treatment approach in tetanus: Botulinum toxin.

    PubMed

    Demir, Nazlim Aktug; Sumer, Sua; Ural, Onur; Ozturk, Serefnur; Celik, Jale Bengi

    2015-01-01

    Tetanus is a preventable infectious disease caused by tetanus toxin (tetanospasmin) produced by Clostridium tetani. Tetanus is still an important health problem in low- and middle-income countries (LMICs). Botulinum toxin administration is a treatment approach that has been used in recent years to reduce rigidity and spasms in tetanus patients. This case report focuses on its efficacy. PMID:25234426

  15. Can the immunological response to botulinum toxin trigger headaches?

    PubMed

    Baizabal-Carvallo, José Fidel

    2015-01-01

    OnabotulinumtoxinA has recently proved beneficial for the treatment of chronic migraine; even though, headaches are not infrequently reported by patients receiving botulinum toxins for different conditions. Here the author discusses the potential mechanisms on how the immunological response following the application of botulinum toxins may trigger headaches and/or migraine. PMID:25119058

  16. Advanced botulinum toxin techniques against wrinkles in the upper face

    Microsoft Academic Search

    Giovanni Salti; Ilaria Ghersetich

    2008-01-01

    The use of botulinum toxin type A for facial rejuvenation is one of the most common procedure in esthetic medicine. Overall clinical and study experience with botulinum toxin type A for facial enhancement has confirmed that it is effective and safe even in the long term. The different injection techniques, the starting doses, the sex, the dilution, and the storing

  17. Toxins of a Blue-Green Alga: Similarity to Saxitoxin

    Microsoft Academic Search

    Eugene Jackim; John Gentile

    1968-01-01

    Toxins were isolated from the freshwater blue-green alga Aphanizomenon flos-aquae. The toxic fractions were characterized by paper and thin-layer chromatography, isolation characteristics, infrared spectra, physiological activity, and reactivity with specific color reagents. The toxic fractions appear to be similar, if not identical, to saxitoxin (paralytic shellfish toxin), which is produced by the marine dinoflagellate Gonyaulax catenella.

  18. Associations between heat shock protein 70 genetic polymorphisms and calving traits in crossbred Brahman cows

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Stressors such as heat, cold, toxins, and oxygen deprivation are known to induce heat shock proteins. Genetic polymorphisms associated with heat shock protein genes have been associated with decreased male and female fertility. Our objectives were to 1) confirm single nucleotide polymorphisms (SNP) ...

  19. Treatment of Gastrointestinal Sphincters Spasms with Botulinum Toxin A

    PubMed Central

    Brisinda, Giuseppe; Sivestrini, Nicola; Bianco, Giuseppe; Maria, Giorgio

    2015-01-01

    Botulinum toxin A inhibits neuromuscular transmission. It has become a drug with many indications. The range of clinical applications has grown to encompass several neurological and non-neurological conditions. One of the most recent achievements in the field is the observation that botulinum toxin A provides benefit in diseases of the gastrointestinal tract. Although toxin blocks cholinergic nerve endings in the autonomic nervous system, it has also been shown that it does not block non-adrenergic non-cholinergic responses mediated by nitric oxide. This has promoted further interest in using botulinum toxin A as a treatment for overactive smooth muscles and sphincters. The introduction of this therapy has made the treatment of several clinical conditions easier, in the outpatient setting, at a lower cost and without permanent complications. This review presents current data on the use of botulinum toxin A in the treatment of pathological conditions of the gastrointestinal tract. PMID:26035487

  20. [The influence of bacterial toxins on the carcinogenesis].

    PubMed

    Stachowicz, Anna M; ?aniewski, Pawe?; Jagusztyn-Krynicka, Elzbieta K

    2010-01-01

    Bacterial infections may constitute an important risk factor of developing cancer disease. Molecular mechanisms by which bacteria contribute to cancer are extremely complex and still remain not fully understood. So far, it is generally accepted that Helicobacter pylori infections are associated with induction of gastric adenocarcinoma and MALT lymphoma. Two H. pylori toxins which modulate many cellular functions are VacA and CagA. So far, CagA is the only one known bacterial oncoprotein. However, many other bacteria produce toxins or effector proteins perturbing host cell homeostasis or/and evoking chronic inflammation. Both processes may be associated with tumour formation. Bacterial toxins which interfere, with various host signal transduction pathways, deregulate processes of cell division, proliferation and differentiation and modulate apoptosis. Some toxins cause even direct DNA damage. This review discuss the potential links between action of bacterial toxins and cancer. PMID:21473043

  1. Staphylococcus aureus ?-toxin modulates skin host response to viral infection

    PubMed Central

    Bin, Lianghua; Kim, Byung Eui; Brauweiler, Anne; Goleva, Elena; Streib, Joanne; Ji, Yinduo; Schlievert, Patrick M.; Leung, Donald Y. M.

    2012-01-01

    Background Patients with atopic dermatitis (AD) with a history of eczema herpeticum have increased staphylococcal colonization and infections. However, whether Staphylococcus aureus alters the outcome of skin viral infection has not been determined. Objective We investigated whether S aureus toxins modulated host response to herpes simplex virus (HSV) 1 and vaccinia virus (VV) infections in normal human keratinocytes (NHKs) and in murine infection models. Methods NHKs were treated with S aureus toxins before incubation of viruses. BALB/c mice were inoculated with S aureus 2 days before VV scarification. Viral loads of HSV-1 and VV were evaluated by using real-time PCR, a viral plaque-forming assay, and immunofluorescence staining. Small interfering RNA duplexes were used to knockdown the gene expression of the cellular receptor of ?-toxin, a disintegrin and metalloprotease 10 (ADAM10). ADAM10 protein and ?-toxin heptamers were detected by using Western blot assays. Results We demonstrate that sublytic staphylococcal ?-toxin increases viral loads of HSV-1 and VV in NHKs. Furthermore, we demonstrate in vivo that the VV load is significantly greater (P < .05) in murine skin inoculated with an ?-toxin–producing S aureus strain compared with murine skin inoculated with the isogenic ?-toxin–deleted strain. The viral enhancing effect of ?-toxin is mediated by ADAM10 and is associated with its poreforming property. Moreover, we demonstrate that ?-toxin promotes viral entry in NHKs. Conclusion The current study introduces the novel concept that staphylococcal ?-toxin promotes viral skin infection and provides a mechanism by which S aureus infection might predispose the host toward disseminated viral infections. PMID:22840852

  2. Retrocyclins neutralize bacterial toxins by potentiating their unfolding.

    PubMed

    Kudryashova, Elena; Seveau, Stephanie; Lu, Wuyuan; Kudryashov, Dmitri S

    2015-04-15

    Defensins are a class of immune peptides with a broad range of activities against bacterial, fungal and viral pathogens. Besides exerting direct anti-microbial activity via dis-organization of bacterial membranes, defensins are also able to neutralize various unrelated bacterial toxins. Recently, we have demonstrated that in the case of human ?- and ?-defensins, this later ability is achieved through exploiting toxins' marginal thermodynamic stability, i.e. defensins act as molecular anti-chaperones unfolding toxin molecules and exposing their hydrophobic regions and thus promoting toxin precipitation and inactivation [Kudryashova et al. (2014) Immunity 41, 709-721]. Retrocyclins (RCs) are humanized synthetic ?-defensin peptides that possess unique cyclic structure, differentiating them from ?- and ?-defensins. Importantly, RCs are more potent against some bacterial and viral pathogens and more stable than their linear counterparts. However, the mechanism of bacterial toxin inactivation by RCs is not known. In the present study, we demonstrate that RCs facilitate unfolding of bacterial toxins. Using differential scanning fluorimetry (DSF), limited proteolysis and collisional quenching of internal tryptophan fluorescence, we show that hydrophobic regions of toxins normally buried in the molecule interior become more exposed to solvents and accessible to proteolytic cleavage in the presence of RCs. The RC-induced unfolding of toxins led to their precipitation and abrogated activity. Toxin inactivation by RCs was strongly diminished under reducing conditions, but preserved at physiological salt and serum concentrations. Therefore, despite significant structural diversity, ?-, ?- and ?-defensins employ similar mechanisms of toxin inactivation, which may be shared by anti-microbial peptides from other families. PMID:25670244

  3. Mass spectrometric detection of protein-based toxins.

    PubMed

    Tevell Åberg, Annica; Björnstad, Kristian; Hedeland, Mikael

    2013-09-01

    This review focuses on mass spectrometric detection of protein-based toxins, which are among the most toxic substances known. Special emphasis is given to the bacterial toxins botulinum neurotoxin from Clostridium botulinum and anthrax toxins from Bacillus anthracis as well as the plant toxin ricin produced by Ricinus communis. A common feature, apart from their extreme toxicity, is that they are composed of 2 polypeptide chains, one of which is responsible for cell uptake and another that has enzymatic function with the ability to destroy basic cellular functions. These toxins pose a threat, both regarding natural spread and from a terrorism perspective. In order for public health and emergency response officials to take appropriate action in case of an outbreak, whether natural or intentional, there is a need for fast and reliable detection methods. Traditionally, large molecules like proteins have been detected using immunological techniques. Although sensitive, these methods suffer from some drawbacks, such as the risk of false-positives due to cross-reactions and detection of inactive toxin. This article describes recently developed instrumental methods based on mass spectrometry for the reliable detection of botulinum neurotoxins, anthrax toxins, and ricin. Unequivocal identification of a protein toxin can be carried out by mass spectrometry-based amino acid sequencing. Furthermore, in combination with antibody affinity preconcentration and biochemical tests with mass spectrometric detection demonstrating the toxin's enzymatic activity, very powerful analytical methods have been described. In conclusion, the advent of sensitive, easily operated mass spectrometers provides new possibilities for the detection of protein-based toxins. PMID:23971809

  4. Shiga toxin-producing Escherichia coli

    PubMed Central

    Etcheverría, Analía Inés; Padola, Nora Lía

    2013-01-01

    Shiga toxin-producing Escherichia coli (STEC) cause hemorrhagic colitis (HC) and hemolytic uremic syndrome (HUS) in humans. Outbreaks are linked to bovine food sources. STEC O157:H7 has been responsible for the most severe outbreaks worldwide. However, non-O157 serotypes have emerged as important enteric pathogens in several countries. The main virulence factor of STEC is the production of Shiga toxins 1 and 2. Additional virulence markers are a plasmid-encoded enterohemolysin (ehxA), an autoagglutinating adhesin (Saa), a catalase-peroxidase (katP), an extracellular serine protease (espP), a zinc metalloprotease (stcE), a subtilase cytotoxin (subAB), among others. Other virulence factors are intimin and adhesins that had a roll in the adherence of STEC to bovine colon. This review focuses on the virulence traits of STEC and especially on those related to the adhesion to bovine colon. The known of the interaction between STEC and the bovine host is crucial to develop strategies to control cattle colonization. PMID:23624795

  5. Spectroscopic study of food and food toxins

    NASA Astrophysics Data System (ADS)

    King, Gavin; Walsh, James E.; Martin, Suzanne

    2003-03-01

    Fungal infection of food causes billions of dollars of lost revenue per annum as well as health problems, to animals and humans, if consumed in sufficient quantities. Modern food sorting techniques rely on colour or other physical characteristics to filter diseased or otherwise unsuitable foodstuffs from healthy foodstuffs. Their speeds are such that up to 40,000 objects per second can be moved at 4 metres per second, through 1 m wide chutes that offer a wide view for colour and shape sorting. Grain type foods such as coffee or peanuts are often vulnerable to toxic infection from invading fungi. If this happens, then their texture, taste and colour can change. Up to now, only visible wavelengths and colour identification have been used to bulk-sort food, but there has been little research in the ultra violet regions of the spectrum to help identify fungus or toxin infection. This research specifically concentrated on the ultra violet (UV) spectral characteristics of food in an attempt to identify possible spectral changes that occur when healthy food items like peanuts become infected with toxin-producing fungi. Ultimately, the goal is to design, build and construct an optical detection system that can use these 'spectral fingerprints' to more quickly and efficiently detect toxically infected food items.

  6. Labile carbon regulates protease activity and nitrogen acquisition in boreal forest topsoil.

    NASA Astrophysics Data System (ADS)

    Lindén, A.; Heinonsalo, J.; Oinonen, M.; Sonninen, E.; Hilasvuori, E.; Pumpanen, J.

    2012-04-01

    In boreal zone, soil organic matter (SOM) contains a substantial amount of recalcitrant material and forms a large nitrogen pool. However, this pool is to a great extent inaccessible to plants, due to its low decomposability. Although, the nitrogen supply is the most limiting factor of net ecosystem production (NEP) in boreal forests, it has been speculated that as a result of the accelerated decomposition of SOM induced by climate warming, part of this nitrogen pool could be released. It has also been shown that a substantial proportion of gross primary production (GPP) is allocated below ground and acts as an energy source for decomposing rhizomicrobial organisms, and that changes in the GPP rate could therefore increase the belowground turn over rate of otherwise recalcitrant nitrogen-rich SOM. We were studying the effects of increasing labile carbon input on the symbiotic microbial N acquisition and protease activities in a controlled microcosm experiment. We compared the natural abundance of isotope ratios of 13C and 14C in soil CO2efflux, protease enzyme activity, natural abundance of 15N in the needles, and microbial biomass in microcosms containing bare soil and tree seedlings. In addition, we had treatments were additional energy was given to the bare soil and seedling microcosms in the form of glucose. The age of the CO2 originating from the decomposition process of SOM was older in all treatments where easily decomposable carbon (energy) was available for soil microorganisms. The increased natural abundance of 15N in the needles of the seedlings treated with glucose, suggests a shift in nitrogen acquisition to different SOM pool, which was reflected strongly to the total N content of the SOM and evolving 13C signature in soil CO2 efflux. The protease activity was highest in treatments with artificial glucose addition. Our results suggest that the increased input of easily available carbon from aboveground enables the decomposition of recalcitrant nitrogen rich compounds in SOM and could therefore increase the nitrogen supply to plants.

  7. Molybdenum(VI) speciation in sulfidic waters: Stability and lability of thiomolybdates

    SciTech Connect

    Erickson, B.E.; Helz, G.R.

    2000-04-01

    Molybdenum in sedimentary rocks and sediments has evoked interest as a paleo-environmental indicator of reducing conditions. This application demands better understanding of Mo deposition mechanisms and in turn, requires improved knowledge of Mo speciation in anaerobic natural waters. In sulfidic solution, molybdate undergoes sulfidation in four steps that conserve Mo{sup VI} and lead to tetrathiomolybdate. Equilibrium constants and rate constants have been measured by UV-visible spectroscopy. The monothio to trithio-intermediates have negligible stability fields. If H{sub 2}S(aq) increases slowly enough to maintain near-equilibrium conditions, a sharp switch will occur from MoO{sub 4}{sup 2{minus}} to MoS{sub 4}{sup 2{minus}} at {approximately}11 {micro}M H{sub 2}S(aq) (298 K, 1 atm). Sulfide actuation of the switch depends on a{sub H2S}{sup 4}, so a {approximately}3-fold change in a{sub H2S} produces a {approximately}100-fold change in MoO{sub 4}{sup 2{minus}}/MoS{sub 4}{sup 2{minus}}. Conversion of the predominant anion from a hard to a soft base alters Mo's geochemical behavior, increasing its susceptibility to scavenging. Because each successive sulfidation reaction is {approximately}1 order of magnitude slower than the previous one, dithio- {r_reversible} trithio- and trithio {r_reversible} tetrathiomolybdate equilibria might not be achieved in seasonally or intermittently sulfidic waters. In such environments, unstable mixtures of intermediate thiomolybdates can predominate, contradicting thermodynamic predictions. The sulfidation reactions are acid catalyzed. Anoxic sediment porewaters, which are enriched relative to overlying waters in Broensted acids, will promote conversion of molybdate to thiomolybdates. This may account for observations that Mo deposition in euxinic environments occurs often by diagenetic pathways rather than by water column scavenging. Slow hydrolysis and oxidation of MoS{sub 4}{sup 2{minus}} suggests that it could serve a reservoir of fixed, but acid-labile sulfide in oxic waters.

  8. Development of a Diphtheria Toxin-Based Recombinant Porcine IL-2 Fusion Toxin for Depleting Porcine CD25+ Cells

    PubMed Central

    Peraino, Jaclyn Stromp; Schenk, Marian; Li, Guoying; Zhang, Huiping; Farkash, Evan A.; Sachs, David H.; Huang, Christene A.; Duran-Struuck, Raimon; Wang, Zhirui

    2013-01-01

    Regulatory T cells (Tregs) have been widely recognized as crucial players in controlling immune responses. Because their major role is to ensure that the immune system is not over reactive, Tregs have been the focus of multiple research studies including those investigating transplantation tolerance, autoimmunity and cancer treatment. On their surface Tregs constitutively express CD25, a high affinity receptor for the cytokine interleukin-2 (IL-2). The reagents constructed in this study were generated by genetically linking porcine IL-2 to the truncated diphtheria toxin (DT390). This reagent functions by first binding to the cell surface via the porcine IL-2/porcine CD25 interaction then the DT390 domain facilitates internalization followed by inhibition of protein synthesis resulting in cell death. Four versions of the porcine IL-2 fusion toxin were designed in an interest to find the most effective isoform: 1) monovalent glycosylated porcine IL-2 fusion toxin (Gly); 2) monovalent non-N-glycosylated porcine IL-2 fusion toxin (NonGly); 3) bivalent glycosylated porcine IL-2 fusion toxin (Bi-Gly); 4) bivalent non-N-glycosylated porcine IL-2 fusion toxin (Bi-NonGly). Using a porcine CD25+ B cell lymphoma cell line (LCL13271) in vitro analysis of the fusion toxins’ ability to inhibit protein synthesis demonstrated that the Bi-NonGly fusion toxin is the most efficient reagent. These in vitro results are consistent with binding affinity as the Bi-NonGly fusion toxin binds strongest to CD25 on the same LCL13271 cells. The Bi-Gly fusion toxin significantly prolonged the survival (p=0.028) of tumor-bearing NOD/SCID IL-2 receptor ??/? (NSG) mice injected with LCL13271 cells compared with untreated controls. This recombinant protein has great potential to function as a useful tool for in vivo depletion of porcine CD25+ cells for studying immune regulation. PMID:24055128

  9. Potentially Labile Soil Organic Matter in Erosional and Depositional Settings of an Undisturbed Zero-order Watershed

    NASA Astrophysics Data System (ADS)

    Berhe, A. A.; Harden, J. W.; Torn, M. S.; Burton, S. D.; Kleber, M.; Harte, J.

    2006-12-01

    In eroding slopes and depositional settings, the magnitude and significance of soil erosion induced terrestrial carbon dioxide sink is closely associated with how much of the soil organic matter is available in potentially labile form, as free or occluded light fraction (fLF and oLF, respectively) and its stability. Here we use (a) density fractionation to determine the amount of light fraction soil organic carbon (SOC), (b) solid state 13C-NMR of light fraction vs. bulk and mineral associated (dense) fraction SOC to determine chemical composition of the organic constituents, (c) incubation experiment to determine the labile fraction of bioavailable C, and (d) 14C content to determine the stability of SOC at two each eroding slope positions and depositional settings of an undisturbed eroding/depositional watershed. We found that the largest amount of light fraction was found at the top- and bottom-most topographic positions of the watershed while the midslope positions had lowest amount of fLF (profile average 4.5% of total C compared to 6% at the topmost summit site and 5.3% at the bottommost plain site) and oLF (profile average 12.7% of total C compared to 16% at the topmost summit site and 18% at the bottommost plain site). Our 13C-NMR and 14C results indicate that below the soil layer actively mixed by pocket gophers the oLF was older and more decomposed at the eroding slopes compared to the depositional settings. The oLF at the bottom of the eroding slope profiles appears to have undergone significant biochemical transformation or exists in a range of decompositional stages. In contrast, fLF buried at the depositional basins is more humified, but not necessarily older. We conclude that the effect of soil erosion and deposition on the magnitude and composition of the potentially labile SOC fraction is not straightforward and changes appreciably depending on the type of depositional basins considered. In general, our findings suggest that labile, physically-protected SOC was prevalent in the lowest lying, wet plain site, whereas SOM at the relatively sloping, and dry hollow appears to be old, and stabilized within aggregates and by chemical interactions with mineral surfaces.

  10. Use of an acid-labile surfactant as an SDS substitute for gel electrophoresis and proteomic analysis.

    PubMed

    Zeller, Martin; Brown, Elizabeth K; Bouvier, Edouard S P; König, Simone

    2002-03-01

    Modern protein identification and analysis relies largely on proteolytic in-gel digestion of proteins separated during polyacrylamide gel electrophoresis (PAGE) followed by mass spectrometric (MS) measurement of the extracted peptides. Sodium dodecyl sulfate (SDS) is routinely used in nonnative PAGE. However, SDS can interfere with MS. We report the use of an acid-labile surfactant (ALS-I) in place of SDS. ALSI is a long chain derivative of 1,3-dioxolane sodium propyloxy sulfate and has similar denaturing and electrophoretic properties as SDS, but it decomposes at low pH and enhances MS detection of proteins. PMID:19498958

  11. Structure of heptameric protective antigen bound to an anthrax toxin receptor: A role for receptor

    E-print Network

    Harrison, Stephen C.

    Structure of heptameric protective antigen bound to an anthrax toxin receptor: A role for receptor of anthrax toxin forms a heptameric prepore. The prepore later undergoes pH-dependent conversion to a pore accomplishes this disruption by secreting a tripartite toxin­ anthrax toxin, consisting of two intracellularly

  12. Surfing on a retrograde wave: how does Shiga toxin reach the endoplasmic reticulum?

    Microsoft Academic Search

    Ludger Johannes; Bruno Goud

    1998-01-01

    Bacterial Shiga toxin and related toxins are endocytosed by higher eukaryotic cells. The toxin protein is then transported via the Golgi apparatus to the endoplasmic reticulum (ER) and into the cytosol, where it exerts its toxic effect. This review discusses current understanding of this retrograde transport pathway and how newly developed modified toxins that allow detection and quantification of specific

  13. A Note on Algal Toxins in Wisconsin Waters Experiencing Blue-green Algal Blooms

    Microsoft Academic Search

    William C. Sonzogni; Wyatt M. Repavich; Jon H. Standridge; Richard E. Wedepohl; James G. Vennie

    1988-01-01

    Certain blue-green algae commonly found in lakes can produce potent toxins during blooms. In Wisconsin there were several incidents over the years when wildlife and domestic deaths were attributed to algal toxins; however, little information existed on how widespread these toxins were in Wisconsin's many lakes and ponds. Thus, a study was undertaken to determine the incidence of measurable toxins

  14. Interactions of cnidarian toxins with the immune system.

    PubMed

    Suput, Dusan

    2011-10-01

    Cnidarians comprise four classes of toxic marine animals: Anthozoa, Cubozoa, Scyphozoa and Hydrozoa. They are the largest and probably the oldest phylum of toxic marine animals. Any contact with a cnidarian, especially the box jellyfish (Chironex fleckeri), can be fatal, but most cnidarians do not possess sufficiently strong venomous apparatus to penetrate the human skin, whereas others rarely come into contact with human beings. Only a small, almost negligible percentage of the vast wealth of cnidarian toxins has been studied in detail. Many polypeptide cnidarian toxins are immunogenic, and cross-reactivity between several jellyfish venoms has been reported. Cnidarians also possess components of innate immunity, and some of those components have been preserved in evolution. On the other hand, cnidarian toxins have already been used for the design of immunotoxins to treat cancer, whereas other cnidarian toxins can modulate the immune system in mammals, including man. This review will focus on a short overview of cnidarian toxins, on the innate immunity of cnidarians, and on the mode of action of cnidarian toxins which can modulate the immune system in mammals. Emphasis is palced on those toxins which block voltage activated potassium channels in the cells of the immune system. PMID:21824078

  15. Dinophysis Toxins: Causative Organisms, Distribution and Fate in Shellfish

    PubMed Central

    Reguera, Beatriz; Riobó, Pilar; Rodríguez, Francisco; Díaz, Patricio A.; Pizarro, Gemita; Paz, Beatriz; Franco, José M.; Blanco, Juan

    2014-01-01

    Several Dinophysis species produce diarrhoetic toxins (okadaic acid and dinophysistoxins) and pectenotoxins, and cause gastointestinal illness, Diarrhetic Shellfish Poisoning (DSP), even at low cell densities (<103 cells·L?1). They are the main threat, in terms of days of harvesting bans, to aquaculture in Northern Japan, Chile, and Europe. Toxicity and toxin profiles are very variable, more between strains than species. The distribution of DSP events mirrors that of shellfish production areas that have implemented toxin regulations, otherwise misinterpreted as bacterial or viral contamination. Field observations and laboratory experiments have shown that most of the toxins produced by Dinophysis are released into the medium, raising questions about the ecological role of extracelular toxins and their potential uptake by shellfish. Shellfish contamination results from a complex balance between food selection, adsorption, species-specific enzymatic transformations, and allometric processes. Highest risk areas are those combining Dinophysis strains with high cell content of okadaates, aquaculture with predominance of mytilids (good accumulators of toxins), and consumers who frequently include mussels in their diet. Regions including pectenotoxins in their regulated phycotoxins will suffer from much longer harvesting bans and from disloyal competition with production areas where these toxins have been deregulated. PMID:24447996

  16. Toxin-Antitoxin Systems as Multilevel Interaction Systems

    PubMed Central

    Goeders, Nathalie; Van Melderen, Laurence

    2014-01-01

    Toxin-antitoxin (TA) systems are small genetic modules usually composed of a toxin and an antitoxin counteracting the activity of the toxic protein. These systems are widely spread in bacterial and archaeal genomes. TA systems have been assigned many functions, ranging from persistence to DNA stabilization or protection against mobile genetic elements. They are classified in five types, depending on the nature and mode of action of the antitoxin. In type I and III, antitoxins are RNAs that either inhibit the synthesis of the toxin or sequester it. In type II, IV and V, antitoxins are proteins that either sequester, counterbalance toxin activity or inhibit toxin synthesis. In addition to these interactions between the antitoxin and toxin components (RNA-RNA, protein-protein, RNA-protein), TA systems interact with a variety of cellular factors, e.g., toxins target essential cellular components, antitoxins are degraded by RNAses or ATP-dependent proteases. Hence, TA systems have the capacity to interact with each other at different levels. In this review, we will discuss the different interactions in which TA systems are involved and their implications in TA system functions and evolution. PMID:24434905

  17. Structural Insights into Bacillus thuringiensis Cry, Cyt and Parasporin Toxins

    PubMed Central

    Xu, Chengchen; Wang, Bi-Cheng; Yu, Ziniu; Sun, Ming

    2014-01-01

    Since the first X-ray structure of Cry3Aa was revealed in 1991, numerous structures of B. thuringiensis toxins have been determined and published. In recent years, functional studies on the mode of action and resistance mechanism have been proposed, which notably promoted the developments of biological insecticides and insect-resistant transgenic crops. With the exploration of known pore-forming toxins (PFTs) structures, similarities between PFTs and B. thuringiensis toxins have provided great insights into receptor binding interactions and conformational changes from water-soluble to membrane pore-forming state of B. thuringiensis toxins. This review mainly focuses on the latest discoveries of the toxin working mechanism, with the emphasis on structural related progress. Based on the structural features, B. thuringiensis Cry, Cyt and parasporin toxins could be divided into three categories: three-domain type ?-PFTs, Cyt toxin type ?-PFTs and aerolysin type ?-PFTs. Structures from each group are elucidated and discussed in relation to the latest data, respectively. PMID:25229189

  18. Toxin Diversity Revealed by a Transcriptomic Study of Ornithoctonus huwena

    PubMed Central

    He, Quanze; Liu, Jinyan; Luo, Ji; Zhu, Li; Lu, Shanshan; Huang, Pengfei; Chen, Xinyi; Zeng, Xiongzhi; Liang, Songping

    2014-01-01

    Spider venom comprises a mixture of compounds with diverse biological activities, which are used to capture prey and defend against predators. The peptide components bind a broad range of cellular targets with high affinity and selectivity, and appear to have remarkable structural diversity. Although spider venoms have been intensively investigated over the past few decades, venomic strategies to date have generally focused on high-abundance peptides. In addition, the lack of complete spider genomes or representative cDNA libraries has presented significant limitations for researchers interested in molecular diversity and understanding the genetic mechanisms of toxin evolution. In the present study, second-generation sequencing technologies, combined with proteomic analysis, were applied to determine the diverse peptide toxins in venom of the Chinese bird spider Ornithoctonus huwena. In total, 626 toxin precursor sequences were retrieved from transcriptomic data. All toxin precursors clustered into 16 gene superfamilies, which included six novel superfamilies and six novel cysteine patterns. A surprisingly high number of hypermutations and fragment insertions/deletions were detected, which accounted for the majority of toxin gene sequences with low-level expression. These mutations contribute to the formation of diverse cysteine patterns and highly variable isoforms. Furthermore, intraspecific venom variability, in combination with variable transcripts and peptide processing, contributes to the hypervariability of toxins in venoms, and associated rapid and adaptive evolution of toxins for prey capture and defense. PMID:24949878

  19. Synthesis of protein in intestinal cells exposed to cholera toxin

    SciTech Connect

    Peterson, J.W.; Berg, W.D. Jr.; Coppenhaver, D.H.

    1987-11-01

    The mechanism by which cyclic adenosine monophosphate (AMP), formed by intestinal epithelial cells in response to cholera toxin, ultimately results in alterations in water and electrolyte transport is poorly understood. Several studies have indicated that inhibitors of transcription or translation block much of the transport of ions and water in the intestine and edema formation in tissue elicited by cholera toxin. Data presented in this study confirmed the inhibitory effects of cycloheximide on cholera toxin-induced fluid accumulation in the rabbit intestinal loop model. Neither cycloheximide nor actinomycin D altered the amount of cyclic AMP that accumulated in intestinal cells and Chinese hamster ovary cells exposed to cholera toxin. An increase in (/sup 3/H) leucine incorporation was readily demonstrable in intestinal epithelial cells from rabbits challenged with Vibrio cholerae. Similarly, intestinal epithelial cells incubated with cholera toxin for 4 hr synthesized substantially more protein than controls as determined by relative incorporation of (/sup 35/S) methionine. Most of the new protein synthesized in response to cholera toxin was membrane associated and of high molecular weight. The possible significance of the toxin-induced protein relative to cholera pathogenesis was discussed.

  20. Conditional cooperativity in toxin–antitoxin regulation prevents random toxin activation and promotes fast translational recovery

    PubMed Central

    Cataudella, Ilaria; Trusina, Ala; Sneppen, Kim; Gerdes, Kenn; Mitarai, Namiko

    2012-01-01

    Many toxin–antitoxin (TA) loci are known to strongly repress their own transcription. This auto-inhibition is often called ‘conditional cooperativity’ as it relies on cooperative binding of TA complexes to operator DNA that occurs only when toxins are in a proper stoichiometric relationship with antitoxins. There has recently been an explosion of interest in TA systems due to their role in bacterial persistence, however the role of conditional cooperativity is still unclear. We reveal the biological function of conditional cooperativity by constructing a mathematical model of the well studied TA system, relBE of Escherichia coli. We show that the model with the in vivo and in vitro established parameters reproduces experimentally observed response to nutritional stress. We further demonstrate that conditional cooperativity stabilizes the level of antitoxin in rapidly growing cells such that random induction of relBE is minimized. At the same time it enables quick removal of free toxin when the starvation is terminated. PMID:22495927

  1. Oral toxicities of Clostridium botulinum type C and D toxins of different molecular sizes.

    PubMed Central

    Ohishi, I; Sakaguchi, G

    1980-01-01

    Clostridium botulinum type C progenitor toxins of different molecule sizes, C-L (16S) and C-M (12S), were purified from cultures of strains 573, Stockholm, and CB-19. C-L toxin showed some hemaggglutinin activity, whereas C-M toxin did not. Neither C-L nor C-M toxin was activated upon trypsinization. Molecular dissociation of purified type C-L and C-M toxins into toxic and nontoxic components was demonstrated by sucrose density gradient ultracentrifugation and diethylaminoethyl-Sephadex chromatography at pH 8.0. The molecular construction of type C progenitor toxin appears to be analogous to that reported for botulinum toxins of other types. C-L and D-L toxins showed higher oral toxicities to mice than did C-M or D-M toxin. Such higher oral toxicities were ascribed to the higher stabilities of these toxins in gastric and intestinal juices. PMID:7399665

  2. From Toxins Targeting Ligand Gated Ion Channels to Therapeutic Molecules

    PubMed Central

    Nasiripourdori, Adak; Taly, Valérie; Grutter, Thomas; Taly, Antoine

    2011-01-01

    Ligand-gated ion channels (LGIC) play a central role in inter-cellular communication. This key function has two consequences: (i) these receptor channels are major targets for drug discovery because of their potential involvement in numerous human brain diseases; (ii) they are often found to be the target of plant and animal toxins. Together this makes toxin/receptor interactions important to drug discovery projects. Therefore, toxins acting on LGIC are presented and their current/potential therapeutic uses highlighted. PMID:22069709

  3. Trace metals: essential nutrients or toxins

    SciTech Connect

    Savory, J.; Wills, M.R. (Department of Pathology, University of Virginia, Charlottesville (United States))

    1992-08-01

    Trace metals play important roles in biological processes, both as essential components and toxins. Monitoring body status of trace metals thus has become an important function of many clinical, industrial, and government laboratories. Deficiencies of some essential trace metals are seen occasionally, but of most importance is the area of metal toxicity resulting from environmental, occupational, accidental, or iatrogenic exposure. Major questions persist about which specimen best reflects body status, and in this regard each metal has different requirements. Blood is used most widely, urine has a few applications, and hair can be used, although external contamination is an ever-present problem. Tissue is by far the best specimen but is not easily obtained. Contamination of specimens during collection and processing must be controlled. Of the instrumental techniques available, atomic absorption spectrometry has been used most widely, particularly with electrothermal and atomization approaches.62 references.

  4. Import and export of bacterial protein toxins.

    PubMed

    Braun, Volkmar; Helbig, Stephanie; Patzer, Silke I; Pramanik, Avijit; Römer, Christin

    2015-02-01

    The paper provides a short overview of three investigated bacterial protein toxins, colicin M (Cma) of Escherichia coli, pesticin (Pst) of Yersinia pestis and hemolysin (ShlAB) of Serratia marcescens. Cma and Pst are exceptional among colicins in that they kill bacteria by degrading the murein (peptidoglycan). Both are released into the medium and bind to specific receptor proteins in the outer membrane of sensitive E. coli cells. Subsequently they are translocated into the periplasm by an energy-consuming process using the proton motive force. For transmembrane translocation the colicins unfold and refold in the periplasm. In the case of Cma the FkpA peptidyl prolyl cis-trans isomerase/chaperone is required. ShlA is secreted and activated through ShlB in the outer membrane by a type Vb secretion mechanism. PMID:25620353

  5. Ferrihydrite containing gel for chemical imaging of labile phosphate species in sediments and soils using diffusive gradients in thin films.

    PubMed

    Santner, Jakob; Prohaska, Thomas; Luo, Jun; Zhang, Hao

    2010-09-15

    We report on a novel binding gel for phosphate, based on ferrihydrite, and its use in diffusive gradients in thin films (DGT) for measuring labile phosphate species in waters, sediments, and soils. An existing method of binding layer preparation was modified to overcome potential problems with deterioration of ferrihydrite due to conversion to goethite. The gel was characterized regarding its suitability for conventional DGT measurements as well as for measuring two-dimensional distributions of P with high spatial resolution using laser ablation-inductively coupled plasma mass spectrometry (LA-ICPMS). The effects of pH, ionic strength and storage time of gels on phosphate binding were investigated and the kinetics of binding and the maximum binding capacity were determined. The gel is shown to have a considerably higher P capacity than the conventional ferrihydrite DGT binding layers. LA-ICPMS analysis of DGT standards with P concentrations ranging from 0.088 ± 0.005 to 4.47 ± 0.16 ?g cm(-2) resulted in reproducible calibration curves which could be described using a simple power function. We demonstrate that the new gel is well suited for analyzing small-scale changes of P concentrations in soils. Moreover, the gel can be used as an alternative to conventional DGT gels that incorporate powdered ferrihydrite, with improved characteristics for the determination of labile phosphate. PMID:20735010

  6. Ferrihydrite Containing Gel for Chemical Imaging of Labile Phosphate Species in Sediments and Soils Using Diffusive Gradients in Thin Films

    PubMed Central

    Santner, Jakob; Prohaska, Thomas; Luo, Jun; Zhang, Hao

    2012-01-01

    We report on a novel binding gel for phosphate, based on ferrihydrite, and its use in diffusive gradients in thin films (DGT) for measuring labile phosphate species in waters, sediments, and soils. An existing method of binding layer preparation was modified to overcome potential problems with deterioration of ferrihydrite due to conversion to goethite. The gel was characterized regarding its suitability for conventional DGT measurements as well as for measuring two-dimensional distributions of P with high spatial resolution using laser ablation-inductively coupled plasma mass spectrometry (LA-ICPMS). The effects of pH, ionic strength and storage time of gels on phosphate binding were investigated and the kinetics of binding and the maximum binding capacity were determined. The gel is shown to have a considerably higher P capacity than the conventional ferrihydrite DGT binding layers. LA-ICPMS analysis of DGT standards with P concentrations ranging from 0.088 ± 0.005 to 4.47 ± 0.16 ?g cm?2 resulted in reproducible calibration curves which could be described using a simple power function. We demonstrate that the new gel is well suited for analyzing small-scale changes of P concentrations in soils. Moreover, the gel can be used as an alternative to conventional DGT gels that incorporate powdered ferrihydrite, with improved characteristics for the determination of labile phosphate. PMID:20735010

  7. Labile pyrogenic dissolved organic carbon in major Siberian Arctic rivers: Implications for wildfire-stream metabolic linkages

    NASA Astrophysics Data System (ADS)

    Myers-Pigg, Allison N.; Louchouarn, Patrick; Amon, Rainer M. W.; Prokushkin, Anatoly; Pierce, Kayce; Rubtsov, Alexey

    2015-01-01

    burning produces a spectrum of thermally altered materials that releases pyrogenic carbon (PyC) to terrestrial, atmospheric, and aquatic systems. Most studies focus on the refractory end of the PyC spectrum, derived from middle- to high-temperature combustion. Low-temperature PyC is produced during wildfires and has been found to be particularly labile and water soluble. Here we find that in each of the major Siberian watersheds, low-temperature fire-derived biomarkers are present in detectable concentrations during all flow regimes of the 2004-2006 sampling period, confirming that PyC is an intrinsic component of the dissolved organic carbon (DOC) pool mobilized by hydrologic events. Gymnosperm combustion, from the southern portions of these watersheds, is the primary source of this Py-DOC input. Using first-order degradation rates and transit times of water through these rivers, about half of the total estimated flux of this material may be remineralized during transport from fire source to river mouth (20-40 days), demonstrating the input of a labile source of PyC to these watersheds.

  8. Field method for rapid quantification of labile organic carbon in hyper-arid desert soils validated by two thermal methods

    NASA Astrophysics Data System (ADS)

    Fletcher, Lauren E.; Valdivia-Silva, Julio E.; Perez-Montaño, Saul; Condori-Apaza, Renee M.; Conley, Catharine A.; Navarro-Gonzalez, Rafael; McKay, Christopher P.

    2014-03-01

    The objective of this work was to develop a field method for the determination of labile organic carbon in hyper-arid desert soils. Industry standard methods rely on expensive analytical equipment that are not possible to take into the field, while scientific challenges require fast turn-around of large numbers of samples in order to characterize the soils throughout this region. Here we present a method utilizing acid-hydrolysis extraction of the labile fraction of organic carbon followed by potassium permanganate oxidation, which provides a quick and inexpensive approach to investigate samples in the field. Strict reagent standardization and calibration steps within this method allowed the determination of very low levels of organic carbon in hyper-arid soils, in particular, with results similar to those determined by the alternative methods of Calcination and Pyrolysis-Gas Chromatography-Mass Spectrometry. Field testing of this protocol increased the understanding of the role of organic materials in hyper-arid environments and allowed real-time, strategic decision making for planning for more detailed laboratory-based analysis.

  9. Anthrax Edema Toxin Impairs Clearance in Mice

    PubMed Central

    Sastalla, Inka; Tang, Shixing; Crown, Devorah; Liu, Shihui; Eckhaus, Michael A.; Hewlett, Indira K.; Leppla, Stephen H.

    2012-01-01

    The anthrax edema toxin (ET) of Bacillus anthracis is composed of the receptor-binding component protective antigen (PA) and of the adenylyl cyclase catalytic moiety, edema factor (EF). Uptake of ET into cells raises intracellular concentrations of the secondary messenger cyclic AMP, thereby impairing or activating host cell functions. We report here on a new consequence of ET action in vivo. We show that in mouse models of toxemia and infection, serum PA concentrations were significantly higher in the presence of enzymatically active EF. These higher concentrations were not caused by ET-induced inhibition of PA endocytosis; on the contrary, ET induced increased PA binding and uptake of the PA oligomer in vitro and in vivo through upregulation of the PA receptors TEM8 and CMG2 in both myeloid and nonmyeloid cells. ET effects on protein clearance from circulation appeared to be global and were not limited to PA. ET also impaired the clearance of ovalbumin, green fluorescent protein, and EF itself, as well as the small molecule biotin when these molecules were coinjected with the toxin. Effects on injected protein levels were not a result of general increase in protein concentrations due to fluid loss. Functional markers for liver and kidney were altered in response to ET. Concomitantly, ET caused phosphorylation and activation of the aquaporin-2 water channel present in the principal cells of the collecting ducts of the kidneys that are responsible for fluid homeostasis. Our data suggest that in vivo, ET alters circulatory protein and small molecule pharmacokinetics by an as-yet-undefined mechanism, thereby potentially allowing a prolonged circulation of anthrax virulence factors such as EF during infection. PMID:22104108

  10. Improved PE-based Targeted Toxins: A Therapeutic with Increased Effectiveness

    Cancer.gov

    A particular toxin that has been used in targeted toxins is Pseudomonas exotoxin A (PE). The effectiveness of PE-containing targeted toxins has been demonstrated against various forms of cancer, including hairy cell leukemia (HCL) and pediatric acute lymphocytic leukemia (pALL). Although early variations these targeted toxins have demonstrated efficacy upon first administration, the continued administration of a targeted toxin often leads to a reduced patient response.

  11. Size, speciation and lability of NOM-metal complexes in hyperalkaline cave dripwater

    NASA Astrophysics Data System (ADS)

    Hartland, Adam; Fairchild, Ian J.; Lead, Jamie R.; Zhang, Hao; Baalousha, Mohammed

    2011-12-01

    Transport of trace metals by natural organic matter (NOM) is potentially an important vector for trace metal incorporation in secondary cave precipitates [speleothems], yet little is known about the size distribution, speciation and metal binding properties of NOM in cave dripwaters. A hyperalkaline cave environment (ca. pH 11) was selected to provide information on colloid-metal interactions in cave waters, and to address the lack of high-pH data in natural systems in general. Colloidal (1 nm-1 ?m) NOM in hyperalkaline cave dripwater from Poole's Cavern, UK, was characterised by flow field-flow fractionation (FlFFF) coupled to UV and fluorescence detectors and transmission electron microscopy (TEM) coupled to X-ray energy-dispersive spectroscopy (X-EDS); trace-metal lability was examined by diffusive gradients in thin films (DGT). Colloidal aggregates and small particulates (>1 ?m) imaged by TEM were morphologically heterogeneous with qualitative elemental compositions (X-EDS spectra; n = 41) consistent with NOM aggregates containing aluminosilicates, and iron and titanium oxides. Globular organic colloids, with diameters between ca. 1 and 10 nm were the most numerous colloidal class and exhibited high UV-absorbance (254 nm) and fluorescence intensity (320:400 nm excitation: emission) in optical regions characteristic of humic-like compounds. Metal binding with humic substances was modelled using the WHAM 6.1 (model VI) and visual MINTEQ 3.0 (NICA-Donnan) speciation codes. At pH 11, both models predicted dominant humic binding of Cu (ca. 100%) and minimal binding of Ni and Co (ca. <1-7%). A DGT depletion experiment (7 days duration) with the hyperalkaline dripwater showed that the available proportion of each metal was much lower than its total concentration. Metal availability for DGT in the initial stages (24 h) was consistent with weaker binding of alkaline earth metals by humic substances (Ba > Sr > V > Cu > Ni > Co), compared to the transition metals. Integrated over the entire experiment, the DGT-available proportion of transition metals (Ni > Cu & V >> Co) differed greatly from the expected hierarchy from WHAM and MINTEQ, indicating unusually strong complexation of Co. Total metal concentrations of Cu, Ni, and Co in raw and filtered PE1 dripwater samples ( n = 53) were well correlated (Cu vs. Ni, R2 = 0.8; Cu vs. Co, R2 = 0.5) and were strongly reduced (> ca. 50%) by filtration at ca. 100 and 1 nm, indicating a common colloidal association. Our results demonstrate that soil-derived colloids reach speleothems, despite transport through a karst zone with potential for adsorption, and that NOM is a dominant complexant of trace metals in high pH speleothem-forming groundwaters.

  12. Anomericity of T-2 toxin-glucoside: masked mycotoxin in cereal crops.

    PubMed

    McCormick, Susan P; Kato, Takayuki; Maragos, Chris M; Busman, Mark; Lattanzio, Veronica M T; Galaverna, Gianni; Dall-Asta, Chiara; Crich, David; Price, Neil P J; Kurtzman, Cletus P

    2015-01-21

    T-2 toxin is a trichothecene mycotoxin produced when Fusarium fungi infect grains, especially oats and wheat. Ingestion of T-2 toxin contaminated grain can cause diarrhea, hemorrhaging, and feed refusal in livestock. Cereal crops infected with mycotoxin-producing fungi form toxin glycosides, sometimes called masked mycotoxins, which are a potential food safety concern because they are not detectable by standard approaches and may be converted back to the parent toxin during digestion or food processing. The work reported here addresses four aspects of T-2 toxin-glucosides: phytotoxicity, stability after ingestion, antibody detection, and the anomericity of the naturally occurring T-2 toxin-glucoside found in cereal plants. T-2 toxin-?-glucoside was chemically synthesized and compared to T-2 toxin-?-glucoside prepared with Blastobotrys muscicola cultures and the T-2 toxin-glucoside found in naturally contaminated oats and wheat. The anomeric forms were separated chromatographically and differ in both NMR and mass spectrometry. Both anomers were significantly degraded to T-2 toxin and HT-2 toxin under conditions that mimic human digestion, but with different kinetics and metabolic end products. The naturally occurring T-2 toxin-glucoside from plants was found to be identical to T-2 toxin-?-glucoside prepared with B. muscicola. An antibody test for the detection of T-2 toxin was not effective for the detection of T-2 toxin-?-glucoside. This anomer was produced in sufficient quantity to assess its animal toxicity. PMID:25520274

  13. Heat-stable proteins and abscisic acid action in barley aleurone cells

    SciTech Connect

    Jacobsen, J.V. (CSIRO, Canberra (Australia)); Shaw, D.C. (Australian National Univ., Canberra (Australia))

    1989-12-01

    ({sup 35}S)Methionine labeling experiments showed that abscisic acid (ABA) induced the synthesis of at least 25 polypeptides in mature barley (Hordeum vulgare) aleurone cells. The polypeptides were not secreted. Whereas most of the proteins extracted from aleurone cells were coagulated by heating to 100{degree}C for 10 minutes, most of the ABA-induced polypeptides remained in solution (heat-stable). ABA had little effect on the spectrum of polypeptides that were synthesized and secreted by aleurone cells, and most of these secreted polypeptides were also heat-stable. Coomassie blue staining of sodium dodecyl sulfate polyacrylamide gels indicated that ABA-induced polypeptides already occurred in high amounts in mature aleurone layers having accumulated during grain development. About 60% of the total protein extracted from mature aleurone was heat stable. Amino acid analyses of total preparations of heat-stable and heat-labile proteins showed that, compared to heat-labile proteins, heat-stable intracellular proteins were characterized by higher glutamic acid/glutamine (Glx) and glycine levels and lower levels of neutral amino acids. Secreted heat-stable proteins were rich in Glx and proline. The possibilities that the accumulation of the heat-stable polypeptides during grain development is controlled by ABA and that the function of these polypeptides is related to their abundance and extraordinary heat stability are considered.

  14. Characterization of a heat-stable fraction of lipovitellin and development of an immunoassay for vitellogenin and yolk protein in winter flounder (Pleuronectes americanus)

    Microsoft Academic Search

    Ruth C. Hartling; Jose J. Pereira; Joseph G. Kunkel

    1997-01-01

    An enzyme-linked immunoabsorbent assay was developed for detection and quan- tification of the yolk protein lipovitellin (Lv) and its plasma precursor, vitellogenin (Vg), in win- ter flounder (Pleuronectes americanus). Native Lv was found to be a mixture of heat-stable and heat-labile molecules in mature, ovulated eggs. A heat-stable Lv fraction was purified from ex- tracts of unfertilized eggs by brief

  15. DEVELOPMENT OF A HUMAN BIOMARKER FOR CYANOBACTERIAL TOXINS- MICROCYSTINS

    EPA Science Inventory

    Increasingly, cyanobacterial blooms are being reported worldwide due to several factors: eutrophication, climate change, and potentially greater scientific awareness and detection. During 1996, an outbreak of fatal cyanobacterial toxin intoxications occurred among a group of dia...

  16. Identification of the cellular receptor for anthrax toxin

    NASA Astrophysics Data System (ADS)

    Bradley, Kenneth A.; Mogridge, Jeremy; Mourez, Michael; Collier, R. John; Young, John A. T.

    2001-11-01

    The tripartite toxin secreted by Bacillus anthracis, the causative agent of anthrax, helps the bacterium evade the immune system and can kill the host during a systemic infection. Two components of the toxin enzymatically modify substrates within the cytosol of mammalian cells: oedema factor (OF) is an adenylate cyclase that impairs host defences through a variety of mechanisms including inhibiting phagocytosis; lethal factor (LF) is a zinc-dependent protease that cleaves mitogen-activated protein kinase kinase and causes lysis of macrophages. Protective antigen (PA), the third component, binds to a cellular receptor and mediates delivery of the enzymatic components to the cytosol. Here we describe the cloning of the human PA receptor using a genetic complementation approach. The receptor, termed ATR (anthrax toxin receptor), is a type I membrane protein with an extracellular von Willebrand factor A domain that binds directly to PA. In addition, a soluble version of this domain can protect cells from the action of the toxin.

  17. Environmental toxins; their impact on children’s health

    Microsoft Academic Search

    J Grigg

    2004-01-01

    Contamination of the environment by man-made and natural toxins has a direct impact on the health of children. This review considers how toxic contamination is identified and regulated, and highlights specific hazards.

  18. NANO APTASENSOR FOR PROTECTIVE ANTIGEN TOXIN OF ANTHRAX

    PubMed Central

    Cella, Lakshmi N.; Sanchez, Pablo; Zhong, Wenwan; Myung, Nosang V.; Chen, Wilfred; Mulchandani, Ashok

    2010-01-01

    We demonstrate a highly sensitive nano aptasensor for anthrax toxin through the detection of its polypeptide entity, protective antigen (PA toxin) using a PA toxin ssDNA aptamer functionalized single-walled carbon nanotubes (SWNTs) device. The aptamer was developed in-house by capillary electrophoresis systematic evolution of ligands by exponential enrichment (CE-SELEX) and had a dissociation constant (Kd) of 112 nM. The aptasensor displayed a wide dynamic range spanning up to 800 nM with a detection limit of 1nM. The sensitivity was 0.11 per nM and it was reusable six times. The aptasensor was also highly selective for PA toxin with no interference from human and bovine serum albumin, demonstrating it as a potential tool for rapid and point-of-care diagnosis for anthrax. PMID:20136122

  19. Nano aptasensor for protective antigen toxin of anthrax.

    PubMed

    Cella, Lakshmi N; Sanchez, Pablo; Zhong, Wenwan; Myung, Nosang V; Chen, Wilfred; Mulchandani, Ashok

    2010-03-01

    We demonstrate a highly sensitive nano aptasensor for anthrax toxin through the detection of its polypeptide entity, protective antigen (PA toxin) using a PA toxin ssDNA aptamer functionalized single-walled carbon nanotubes (SWNTs) device. The aptamer was developed in-house by capillary electrophoresis systematic evolution of ligands by exponential enrichment (CE-SELEX) and had a dissociation constant (K(d)) of 112 nM. The aptasensor displayed a wide dynamic range spanning up to 800 nM with a detection limit of 1 nM. The sensitivity was 0.11 per nM, and it was reusable six times. The aptasensor was also highly selective for PA toxin with no interference from human and bovine serum albumin, demonstrating it as a potential tool for rapid and point-of-care diagnosis for anthrax. PMID:20136122

  20. Lability of the networks of hydrogen bonds in liquid diols and amino alcohols, according to the baric dependence of bulk viscosity

    NASA Astrophysics Data System (ADS)

    Rodnikova, M. N.; Solonina, I. A.; Troitskii, V. M.; Shirokova, E. V.

    2015-03-01

    The bulk viscosity of three vicinal diols and three vicinal amino alcohols is measured on a unique direct compression setup in the pressure range of 0.1-300 MPa. The bulk viscosity of all the liquids is found to grow with increasing pressure. The baric dependence of bulk viscosity is proposed as a lability characteristic of the spatial network of hydrogen bonds. The network of amino alcohols is more labile than in diols, butane derivatives crystallize at 80 MPa (butanediol) and 200-250 MPa (amino butanol), and the other diols and amino alcohols remain liquid over the investigated range of pressures.

  1. Selective tert-butyl ester deprotection in the presence of acid labile protecting groups with use of ZnBr2.

    PubMed

    Kaul, Ramesh; Brouillette, Yann; Sajjadi, Zohreh; Hansford, Karl A; Lubell, William D

    2004-09-01

    Chemoselective hydrolysis of tert-butyl esters in the presence of other acid-labile groups has been explored by employing alpha-amino esters and ZnBr(2) in DCM. Although N-Boc and N-trityl groups were found to be labile, PhF protected amines were compatible with these Lewis acid deprotection conditions such that a variety of N-(PhF)amino acids were prepared in good yields from their corresponding tert-butyl esters. PMID:15373501

  2. ADP-ribosylation of actin from the green alga Chara corallina by Clostridium botulinum C2 toxin and Clostridium perfringens iota toxin

    Microsoft Academic Search

    F. Grolig; I. Just; K. Aktories

    1996-01-01

    Summary The ability of two bacterial toxins to modify a plant actin by covalent ADP-ribosylation was tested in the green algaChara corallina. Using [32P]NAD, bothClostridium botulinum C2 toxin andClostridium perfringens iota toxin labelled a protein of Mr 42 kDa which comigrated with actin and was immunoprecipitated by a monoclonal anti-actin antibody. ADP-ribosylation ofChara actin was more efficient with iota toxin

  3. Production of Bacillus cereus emetic toxin (cereulide) in various foods

    Microsoft Academic Search

    N Agata; M Ohta; K Yokoyama

    2002-01-01

    To determine the role of Bacillus cereus as a potential pathogen in food poisoning, the production of an emetic toxin (cereulide) by B. cereus was quantified in various food sources. The amount of emetic toxin in 13 of 14 food samples implicated in vomiting-type food poisoning cases ranged from 0.01 to 1.28 ?g\\/g. A vomiting-type strain, B. cereus NC7401, was

  4. Biological Properties of Staphylococcal Enterotoxin-Like Toxin Type R

    Microsoft Academic Search

    Katsuhiko Omoe; K. Imanishi; D.-L. Hu; H. Kato; H. Takahashi-Omoe; A. Nakane; T. Uchiyama; K. Shinagawa

    2004-01-01

    We investigated the biological properties of a novel staphylococcal enterotoxin-like putative toxin, staphy- lococcal enterotoxin-like toxin type R (SElR). Major histocompatibility complex class II molecules were required for T-cell stimulation by SElR. SElR stimulated T cells bearing receptors V 3, 11, 12, 13.2, and 14. These results suggested that SElR acts as a superantigen. Staphylococcus aureus is an important human

  5. Role of Toxin Functional Domains in Anthrax Pathogenesis

    Microsoft Academic Search

    FABIEN BROSSIER; MARTINE WEBER-LEVY; MICHELE MOCK; JEAN-CLAUDE SIRARD

    2000-01-01

    We investigated the role of the functional domains of anthrax toxins during infection. Three proteins produced by Bacillus anthracis, the protective antigen (PA), the lethal factor (LF), and the edema factor (EF), combine in pairs to produce the lethal (PA1LF) and edema (PA1EF) toxins. A genetic strategy was developed to introduce by allelic exchange specific point mutations or in-frame deletions

  6. Botulinum toxin use in pediatric esophageal achalasia: A case report

    Microsoft Academic Search

    J. M Walton; G Tougas

    1997-01-01

    Esophageal achalasia (EA) has been historically treated by esophageal dilatation or myotomy with or without fundoplication. Botulinum toxin (Botox-Allergan) use in pediatric EA has not been previously described. The authors' objective was to observe the efficacy of botulinum toxin injection into the lower esophageal sphincter (LES) for EA. An 11-year-old boy presented with a 9-month history of frequent pneumonia, productive

  7. Field depuration and biotransformation of paralytic shellfish toxins in scallop Chlamys nobilis and green-lipped mussel Perna viridis

    Microsoft Academic Search

    M.-C. Choi; D. P. H. Hsieh; P. K. S. Lam; W.-X. Wang

    2003-01-01

    Under laboratory conditions, the scallop Chlamys nobilis and the mussel Perna viridis were exposed to N-sulfocarbamoyl toxins (C2 toxin), a paralytic shellfish toxin (PST), by feeding a local toxic strain of the dinoflagellate Alexandrium tamarense (ATDP) that produced C2 toxin exclusively. The bivalves were subsequently depurated in the field, and their depuration kinetics, biotransformation and toxin distribution were quantified. Depuration

  8. Binary Toxin and Death after Clostridium difficile Infection

    PubMed Central

    Mølbak, Kåre; Kjeldsen, Marianne K.; Olsen, Katharina E.P.

    2011-01-01

    We compared 30-day case-fatality rates for patients infected with Clostridium difficile possessing genes for toxins A and B without binary toxin (n = 212) with rates for patients infected with C. difficile possessing genes for A, B, and binary toxin. The latter group comprised patients infected with strains of PCR ribotype 027 (CD027, n = 193) or non-027 (CD non-027, n = 72). Patients with binary toxin had higher case-fatality rates than patients without binary toxin, in univariate analysis (relative risk [RR] 1.8, 95% confidence interval [CI] 1.2–2.7) and multivariate analysis after adjustment for age, sex, and geographic region (RR 1.6, 95% CI 1.0–2.4). Similar case-fatality rates (27.8%, 28.0%) were observed for patients infected with CD027 or CD non-027. Binary toxin either is a marker for more virulent C. difficile strains or contributes directly to strain virulence. Efforts to control C. difficile infection should target all virulent strains irrespective of PCR ribotype. PMID:21749757

  9. Disorders of neuromuscular transmission due to natural environmental toxins.

    PubMed

    Senanayake, N; Román, G C

    1992-01-01

    A variety of natural toxins of animal, plant, and bacterial origin are capable of causing disorders of neuromuscular transmission. Animal toxins include venomous snakes and arthropods, venoms of certain marine creatures, skin secretions of dart-poison frogs, and poisonous fish, shellfish, and crabs. There are plant poisons such as curare, and bacterial poisons such as botulinum toxin. These act at single or multiple sites of the neuromuscular apparatus interfering with voltage-gated ion channels, acetylcholine release, depolarization of the postsynaptic membrane, or generation and spread of the muscle action potential. The specific actions of these toxins are being widely exploited in the study of neuromuscular physiology and pathology. Some toxins have proved to be valuable pharmaceutical agents. Poisoning by natural neurotoxins is an important public health hazard in many parts of the world, particularly in the tropics. Poisoning may occur by a bite or a sting of a venomous animal, or by the ingestion of poisonous fish, shellfish or other marine delicacies. Contaminated food is a vehicle for poisons such as botulinum toxin. Clinically, a cardinal feature in the symptomatology is muscle paralysis with a distribution characteristic of myasthenia gravis, affecting muscles innervated by cranial nerves, neck flexors, proximal limb muscles, and respiratory muscles. Respiratory paralysis may end fatally. This paper reviews from the clinical and pathophysiologic viewpoints, naturally occurring environmental neurotoxins acting at the neuromuscular junction. PMID:1315843

  10. Toxin studies using an integrated biophysical and structural biology approach.

    SciTech Connect

    Last, Julie A.; Schroeder, Anne E.; Slade, Andrea Lynn; Sasaki, Darryl Yoshio; Yip, Christopher M. (University of Toronto, Toronto, Ontario, Canada); Schoeniger, Joseph S. (Sandia National Laboratories, Livermore, CA)

    2005-03-01

    Clostridial neurotoxins, such as botulinum and tetanus, are generally thought to invade neural cells through a process of high affinity binding mediated by gangliosides, internalization via endosome formation, and subsequent membrane penetration of the catalytic domain activated by a pH drop in the endosome. This surface recognition and internalization process is still not well understood with regard to what specific membrane features the toxins target, the intermolecular interactions between bound toxins, and the molecular conformational changes that occur as a result of pH lowering. In an effort to elucidate the mechanism of tetanus toxin binding and permeation through the membrane a simple yet representative model was developed that consisted of the ganglioside G{sub tlb} incorporated in a bilayer of cholesterol and DPPC (dipalmitoylphosphatidyl choline). The bilayers were stable over time yet sensitive towards the binding and activity of whole toxin. A liposome leakage study at constant pH as well as with a pH gradient, to mimic the processes of the endosome, was used to elucidate the effect of pH on the toxin's membrane binding and permeation capability. Topographic imaging of the membrane surface, via in situ tapping mode AFM, provided nanoscale characterization of the toxin's binding location and pore formation activity.

  11. Toxin gene determination and evolution in scorpaenoid fish.

    PubMed

    Chuang, Po-Shun; Shiao, Jen-Chieh

    2014-09-01

    In this study, we determine the toxin genes from both cDNA and genomic DNA of four scorpaenoid fish and reconstruct their evolutionary relationship. The deduced protein sequences of the two toxin subunits in Sebastapistes strongia, Scorpaenopsis oxycephala, and Sebastiscus marmoratus are about 700 amino acid, similar to the sizes of the stonefish (Synanceia horrida, and Synanceia verrucosa) and lionfish (Pterois antennata and Pterois volitans) toxins previously published. The intron positions are highly conserved among these species, which indicate the applicability of gene finding by using genomic DNA template. The phylogenetic analysis shows that the two toxin subunits were duplicated prior to the speciation of Scorpaenoidei. The precedence of the gene duplication over speciation indicates that the toxin genes may be common to the whole family of Scorpaeniform. Furthermore, one additional toxin gene has been determined in the genomic DNA of Dendrochirus zebra. The phylogenetic analysis suggests that an additional gene duplication occurred before the speciation of the lionfish (Pteroinae) and a pseudogene may be generally present in the lineage of lionfish. PMID:24950049

  12. Contribution of toxins to the pathogenesis of inhalational anthrax.

    PubMed

    Tournier, Jean-Nicolas; Quesnel-Hellmann, Anne; Cleret, Aurélie; Vidal, Dominique R

    2007-03-01

    Inhalational anthrax is a life-threatening infectious disease of considerable concern, especially as a potential bioterrorism agent. Progress is gradually being made towards understanding the mechanisms used by Bacillus anthracis to escape the immune system and to induce severe septicaemia associated with toxaemia and leading to death. Recent advances in fundamental research have revealed previously unsuspected roles for toxins in various cell types. We summarize here pathological data for animal models and macroscopic histological examination data from recent clinical records, which we link to the effects of toxins. We describe three major steps in infection: (i) an invasion phase in the lung, during which toxins have short-distance effects on lung phagocytes; (ii) a phase of bacillus proliferation in the mediastinal lymph nodes, with local effects of toxins; and (iii) a terminal, diffusion phase, characterized by a high blood bacterial load and by long-distance effects of toxins, leading to host death. The pathophysiology of inhalational anthrax thus involves interactions between toxins and various cell partners, throughout the course of infection. PMID:17223930

  13. Mucosal Adjuvant Properties of Mutant LT-IIa and LT-IIb Enterotoxins That Exhibit Altered Ganglioside-Binding Activities

    Microsoft Academic Search

    Hesham F. Nawar; Sergio Arce; Michael W. Russell; Terry D. Connell

    2005-01-01

    LT-IIa and LT-IIb, the type II heat-labile enterotoxins of Escherichia coli, are closely related in structure and function to cholera toxin and LT-I, the type I heat-labile enterotoxins of Vibrio cholerae and E. coli, respectively. Recent studies from our group demonstrated that LT-IIa and LT-IIb are potent systemic and mucosal adju- vants. To determine whether binding of LT-IIa and LT-IIb

  14. [Effects of the different land use on soil labile organic matter and carbon management index in Junyun Mountain].

    PubMed

    Xu, Peng; Jiang, Chang-Sheng; Hao, Qing-Ju; Zhu, Tao

    2013-10-01

    The impacts of different land use on soil organic matter (SOM), soil labile organic matter (SLOM) and their efficiency ratios (ER), and soil carbon management index (CMI) were studied in this study. Subtropical evergreen broad-leaved forest (abbreviation: forest) , sloping farmland, orchard and abandoned land were selected and soils at the depths of 0-10, 10-20, 20-30, 30-40, 40-50 and 50-60 cm were sampled in the spring of 2011 to determine the contents of soil organic matter and labile organic matter. The results showed that the contents of soil organic matter and soil labile organic matter both decreased with the increase of soil depth under all four land use types; however, forest and orchard enriched SOM and SLOM contents in the 0-10 cm and 0-20 cm soil layers, respectively, while the contents of SOM and SLOM decreased evenly in sloping farmland and abandoned land. In the whole soil layer (0-60 cm) , the order of SOM and SLOM contents was abandoned land > forest > orchard > sloping farmland, indicating that at the conversion from forest into orchard or sloping farmland, SOM was reduced by 21.56% (P >0.05) and 55.90% (P <0.05), respectively, and at the conversion from sloping farmland into abandoned land, the low SLOM, middle SLOM and high SLOM increased by 144.2% (P<0.05) , 153.3% (P <0.05) and 242.7% (P <0.05), respectively. There was no significant difference in low ER, middle ER and high ER among the four land uses as suggested by ANOVA which showed that SRs were not sensible to the change of land use. All three CMis were in the order of abandoned land > forest > orchard > sloping farmland, revealing that forest reclamation resulted in the reduction of soil organic carbon storage and the decline of soil quality, and the abandonment of sloping farmland would increase soil carbon sink and improve soil quality. Three kinds of SLOM were all positively correlated with soil total nitrogen, available phosphorus and available potassium, while negatively correlated with soil density bulk, indicating that SLOM had close relationships with soil physical and chemical characters and could be used as an important index to reflect soil nutrient status and judge soil quality. PMID:24364324

  15. Entry of ricin and Shiga toxin into cells: molecular mechanisms and medical perspectives.

    PubMed

    Sandvig, K; van Deurs, B

    2000-11-15

    A large number of plant and bacterial toxins with enzymatic activity on intracellular targets are now known. These toxins enter cells by first binding to cell surface receptors, then they are endocytosed and finally they become translocated into the cytosol from an intracellular compartment. In the case of the plant toxin ricin and the bacterial toxin Shiga toxin, this happens after retrograde transport through the Golgi apparatus and to the endoplasmic reticulum. The toxins are powerful tools to reveal new pathways in intracellular transport. Furthermore, knowledge about their action on cells can be used to combat infectious diseases where such toxins are involved, and a whole new field of research takes advantage of their ability to enter the cytosol for therapeutic purposes in connection with a variety of diseases. This review deals with the mechanisms of entry of ricin and Shiga toxin, and the attempts to use such toxins in medicine are discussed. PMID:11080141

  16. Cyanobacteria toxins in the Salton Sea

    PubMed Central

    Carmichael, Wayne W; Li, RenHui

    2006-01-01

    Background The Salton Sea (SS) is the largest inland body of water in California: surface area 980 km2, volume 7.3 million acre-feet, 58 km long, 14–22 km wide, maximum depth 15 m. Located in the southeastern Sonoran desert of California, it is 85 m below sea level at its lowest point. It was formed between 1905 and 1907 from heavy river flows of the Colorado River. Since its formation, it has attracted both people and wildlife, including flocks of migratory birds that have made the Salton Sea a critical stopover on the Pacific flyway. Over the past 15 years wintering populations of eared grebe (Podiceps nigricollis) at the Salton Sea, have experienced over 200,000 mortalities. The cause of these large die-offs remains unknown. The unique environmental conditions of the Salton Sea, including salinities from brackish freshwater at river inlets to hypersaline conditions, extreme daily summer temperatures (>38°C), and high nutrient loading from rivers and agricultural drainage favor eutrophic conditions that encourage algal blooms throughout the year. A significant component of these algal blooms are the prokaryotic group – the Cyanophyta or blue-green algae (also called Cyanobacteria). Since many Cyanobacteria produce toxins (the cyanotoxins) it became important to evaluate their presence and to determine if they are a contributing factor in eared-grebe mortalities at the Salton Sea. Results From November 1999 to April 2001, 247 water and sediment samples were received for phytoplankton identification and cyanotoxin analyses. Immunoassay (ELISA) screening of these samples found that eighty five percent of all water samples contained low but detectable levels of the potent cyclic peptide liver toxin called microcystins. Isolation and identification of cyanobacteria isolates showed that the picoplanktonic Synechococcus and the benthic filamentous Oscillatoria were dominant. Both organisms were found to produce microcystins dominated by microcystin-LR and YR. A laboratory strain of Synechococcus was identified by PCR as being closest to known marine forms of this genus. Analyses of affected grebe livers found microcystins at levels that may account for some of the acute mortalities. Conclusion The production of microcystins by a marine Synechococcus indicates that microcystins may be a more common occurrence in marine environments – a finding not recognized before this work. Further research should be done to define the distribution of microcystin producing marine cyanobacteria and to determine exposure/response effects of microcystins and possibly other cyanotoxins in the Salton Sea. Future efforts to reduce avian mortalities and remediate the Salton Sea should evaluate vectors by which microcystins enter avian species and ways to control and mitigate toxic cyanobacteria waterblooms at the Salton Sea. PMID:16623944

  17. Removal of cyanobacterial toxins by sediment passage

    NASA Astrophysics Data System (ADS)

    Gruetzmacher, G.; Boettcher, G.; Chorus, I.; Bartel, H.

    2003-04-01

    Cyanbacterial toxins ("Cyanotoxins") comprise a wide range of toxic substances produced by cyanobacteria ("blue-green algae"). Cyanobacteria occur in surface water word wide and can be found in high concentrations during so-called algal blooms when conditions are favourable (e.g. high nutrient levels, high temperatures). Some cyanobacteria produce hepato- or neurotoxins, of which the hepatotoxic microcystins are the most common in Germany. The WHO guideline value for drinking water was set at 1 ?g/L. However, maximum concentrations in surface water can reach 25 mg/L, so that a secure method for toxin elimination has to be found when this water is used as source water for drinking water production. In order to assess if cyanotoxins can be removed by sediment passage the German Federal Environmental Agency (UBA) conducted laboratory- and field scale experiments as well as observations on bank filtration field sites. Laboratory experiments (batch- and column experiments for adsorption and degradation parameters) were conducted in order to vary a multitude of experimental conditions. These experiments were followed by field scale experiments on the UBA's experimental field in Berlin. This plant offers the unique possibility to conduct experiments on the behaviour of various agents - such as harmful substances - during infiltration and bank filtration under well-defined conditions on a field scale, and without releasing these substances to the environment. Finally the development of microcystin concentrations was observed between infiltrating surface water and a drinking water well along a transsecte of observation wells. The results obtained show that infiltration and bank filtration normally seem to be secure treatment methods for source water contaminated by microcystins. However, elimination was shown to be difficult under the following circumstances: - dying cyanobacterial population due to insufficient light and / or nutrients, low temperatures or application of algizides (high amount of extracellular microcystins), - sandy material with low shares of clay and silt (little adsorption), - low temperatures (delayed biodegradation), - anoxic conditions (delayed biodegradation), - missing clogging layer or "schmutzdecke" (little bacteria), - no previous contact to microcystins (non adapted bacteria). It is therefore the aim of a new project financed by the KompetenzZentrum Wasser Berlin (KWB) to focus on these critical circumstances in order to find out how to optimise artificial recharge and bank filtration regarding microcystin elimination.

  18. Heating with waste heat

    SciTech Connect

    Beabout, R.W.

    1986-09-02

    Most of the power consumed in the gaseous diffusion process is converted into heat of compression, which is removed from the process gas and rejected into the atmosphere by recirculating cooling water over cooling towers. The water being handled through the X-333 and X-330 Process Buildings can be heated to 140 to 150/sup 0/F for heating use. The Gas Centrifuge Enrichment Plant is provided with a recirculating heating water (RHW) system which uses X-330 water and wasted heat. The RHW flow is diagrammed. (DLC)

  19. TEEX tackles toxins: TEEX develops ECLOX protocols to detect toxins in drinking water 

    E-print Network

    Jordan, Leslie

    2010-01-01

    photo by Martial Voltier, TEEX Photo manipulation Mary-Margaret Shread TEEX tackles toxins continued tx H2O | pg. 10 ?After years of work, Texas is now ECLOX central?there?s no other state with as much background data on drinking water. Other... and TCEQ plan to develop ECLOX protocols for 12 more cities in Texas?helping ensure safe drinking water throughout the state. ?This work is important to Texas,? McLeroy said. ?Because we have worked with TCEQ to develop ECLOX background data...

  20. Do the A Subunits Contribute to the Differences in the Toxicity of Shiga Toxin 1 and Shiga Toxin 2?

    PubMed Central

    Basu, Debaleena; Tumer, Nilgun E.

    2015-01-01

    Shiga toxin producing Escherichia coli O157:H7 (STEC) is one of the leading causes of food-poisoning around the world. Some STEC strains produce Shiga toxin 1 (Stx1) and/or Shiga toxin 2 (Stx2) or variants of either toxin, which are critical for the development of hemorrhagic colitis (HC) or hemolytic uremic syndrome (HUS). Currently, there are no therapeutic treatments for HC or HUS. E. coli O157:H7 strains carrying Stx2 are more virulent and are more frequently associated with HUS, which is the most common cause of renal failure in children in the US. The basis for the increased potency of Stx2 is not fully understood. Shiga toxins belong to the AB5 family of protein toxins with an A subunit, which depurinates a universally conserved adenine residue in the ?-sarcin/ricin loop (SRL) of the 28S rRNA and five copies of the B subunit responsible for binding to cellular receptors. Recent studies showed differences in the structure, receptor binding, dependence on ribosomal proteins and pathogenicity of Stx1 and Stx2 and supported a role for the B subunit in differential toxicity. However, the current data do not rule out a potential role for the A1 subunits in the differential toxicity of Stx1 and Stx2. This review highlights the recent progress in understanding the differences in the A1 subunits of Stx1 and Stx2 and their role in defining toxicity. PMID:25938272

  1. Do the A subunits contribute to the differences in the toxicity of Shiga toxin 1 and Shiga toxin 2?

    PubMed

    Basu, Debaleena; Tumer, Nilgun E

    2015-05-01

    Shiga toxin producing Escherichia coli O157:H7 (STEC) is one of the leading causes of food-poisoning around the world. Some STEC strains produce Shiga toxin 1 (Stx1) and/or Shiga toxin 2 (Stx2) or variants of either toxin, which are critical for the development of hemorrhagic colitis (HC) or hemolytic uremic syndrome (HUS). Currently, there are no therapeutic treatments for HC or HUS. E. coli O157:H7 strains carrying Stx2 are more virulent and are more frequently associated with HUS, which is the most common cause of renal failure in children in the US. The basis for the increased potency of Stx2 is not fully understood. Shiga toxins belong to the AB5 family of protein toxins with an A subunit, which depurinates a universally conserved adenine residue in the ?-sarcin/ricin loop (SRL) of the 28S rRNA and five copies of the B subunit responsible for binding to cellular receptors. Recent studies showed differences in the structure, receptor binding, dependence on ribosomal proteins and pathogenicity of Stx1 and Stx2 and supported a role for the B subunit in differential toxicity. However, the current data do not rule out a potential role for the A1 subunits in the differential toxicity of Stx1 and Stx2. This review highlights the recent progress in understanding the differences in the A1 subunits of Stx1 and Stx2 and their role in defining toxicity. PMID:25938272

  2. Anthrax Lethal Factor Cleaves Mouse Nlrp1b in Both Toxin-Sensitive and Toxin-Resistant Macrophages

    PubMed Central

    Hellmich, Kristina A.; Levinsohn, Jonathan L.; Fattah, Rasem; Newman, Zachary L.; Maier, Nolan; Sastalla, Inka; Liu, Shihui; Leppla, Stephen H.; Moayeri, Mahtab

    2012-01-01

    Anthrax lethal factor (LF) is the protease component of anthrax lethal toxin (LT). LT induces pyroptosis in macrophages of certain inbred mouse and rat strains, while macrophages from other inbred strains are resistant to the toxin. In rats, the sensitivity of macrophages to toxin-induced cell death is determined by the presence of an LF cleavage sequence in the inflammasome sensor Nlrp1. LF cleaves rat Nlrp1 of toxin-sensitive macrophages, activating caspase-1 and inducing cell death. Toxin-resistant macrophages, however, express Nlrp1 proteins which do not harbor the LF cleavage site. We report here that mouse Nlrp1b proteins are also cleaved by LF. In contrast to the situation in rats, sensitivity and resistance of Balb/cJ and NOD/LtJ macrophages does not correlate to the susceptibility of their Nlrp1b proteins to cleavage by LF, as both proteins are cleaved. Two LF cleavage sites, at residues 38 and 44, were identified in mouse Nlrp1b. Our results suggest that the resistance of NOD/LtJ macrophages to LT, and the inability of the Nlrp1b protein expressed in these cells to be activated by the toxin are likely due to polymorphisms other than those at the LF cleavage sites. PMID:23152930

  3. Toxin gene expression by shiga toxin-producing Escherichia coli: the role of antibiotics and the bacterial SOS response.

    PubMed Central

    Kimmitt, P. T.; Harwood, C. R.; Barer, M. R.

    2000-01-01

    Toxin synthesis by Shiga toxin-producing Escherichia coli (STEC) appears to be coregulated through induction of the integrated bacteriophage that encodes the toxin gene. Phage production is linked to induction of the bacterial SOS response, a ubiquitous response to DNA damage. SOS-inducing antimicrobial agents, particularly the quinolones, trimethoprim, and furazolidone, were shown to induce toxin gene expression in studies of their effects on a reporter STEC strain carrying a chromosome-based stx2::lacZ transcriptional fusion. At antimicrobial levels above those required to inhibit bacterial replication, these agents are potent inducers (up to 140-fold) of the transcription of type 2 Shiga toxin genes (stx2); therefore, they should be avoided in treating patients with potential or confirmed STEC infections. Other agents (20 studied) and incubation conditions produced significant but less striking effects on stx2 transcription; positive and negative influences were observed. SOS-mediated induction of toxin synthesis also provides a mechanism that could exacerbate STEC infections and increase dissemination of stx genes. These features and the use of SOS-inducing antibiotics in clinical practice and animal husbandry may account for the recent emergence of STEC disease. PMID:10998375

  4. Why are defensive toxins so variable? An evolutionary perspective.

    PubMed

    Speed, Michael P; Ruxton, Graeme D; Mappes, Johanna; Sherratt, Thomas N

    2012-11-01

    Defensive toxins are widely used by animals, plants and micro-organisms to deter natural enemies. An important characteristic of such defences is diversity both in the quantity of toxins and the profile of specific defensive chemicals present. Here we evaluate evolutionary and ecological explanations for the persistence of toxin diversity within prey populations, drawing together a range of explanations from the literature, and adding new hypotheses. We consider toxin diversity in three ways: (1) the absence of toxicity in a proportion of individuals in an otherwise toxic prey population (automimicry); (2) broad variation in quantities of toxin within individuals in the same population; (3) variation in the chemical constituents of chemical defence. For each of these phenomena we identify alternative evolutionary explanations for the persistence of variation. One important general explanation is diversifying (frequency- or density-dependent) selection in which either costs of toxicity increase or their benefits decrease with increases in the absolute or relative abundance of toxicity in a prey population. A second major class of explanation is that variation in toxicity profiles is itself nonadaptive. One application of this explanation requires that predator behaviour is not affected by variation in levels or profiles of chemical defence within a prey population, and that there are no cost differences between different quantities or forms of toxins found within a population. Finally, the ecology and life history of the animal may enable some general predictions about toxin variation. For example, in animals which only gain their toxins in their immature forms (e.g. caterpillars on host plants) we may expect a decline in toxicity during adult life (or at least no change). By contrast, when toxins are also acquired during the adult form, we may for example expect the converse, in which young adults have less time to acquire toxicity than older adults. One major conclusion that we draw is that there are good reasons to consider within-species variation in defensive toxins as more than mere ecological noise. Rather there are a number of compelling evolutionary hypotheses which can explain and predict variation in prey toxicity. PMID:22540874

  5. NMR study of the exchange rates of allosterically responsive labile protons in the heme pockets of hemoglobin A.

    PubMed Central

    Jue, T; La Mar, G N; Han, K; Yamamoto, Y

    1984-01-01

    1H NMR spectroscopy has been used to measure the proximal histidyl labile ring proton (NH) rates of exchange with bulk solvent in the individual subunits of hemoglobin (Hb) A. These protons displayed a substantial decrease in their exchange rates in comparison with related monomeric proteins and exhibited sensitivity to the quarternary state. With the beta subunit NH, the exchange behaviour was similar to an allosterically responsive subset of protons, which have been identified using 1H-3H methods (Englander, J.J., R. Rogero, and S. W. Englander, 1983, J. Mol. Biol. 169:325-344). Assuming similar exchange mechanisms for the two subunits, the NMR data suggested a more flexible alpha than beta subunit in Hb A. PMID:6331541

  6. Comparison of two experimental speciation methods with a theoretical approach to monitor free and labile Cd fractions in soil solutions.

    PubMed

    Parat, C; Cornu, J-Y; Schneider, A; Authier, L; Sapin-Didier, V; Denaix, L; Potin-Gautier, M

    2009-08-26

    This work focused on the suitability of two techniques to monitor cadmium speciation in soil solutions collected during a 7-day incubation of a contaminated soil. Anodic stripping voltammetry (ASV) and ion exchange were performed on soil solutions collected daily and results were compared with calculations obtained with the speciation software Visual MINTEQ. The electrochemically labile Cd fraction was greater than the exchange-estimated free Cd fraction during the first 6 days, after which it decreased sharply during the last 2 days to reach values close to the exchange-estimated free Cd fraction. Further investigations showed that the increase in pH was mainly responsible for the reduction. However, calculations performed with Visual MINTEQ software clearly demonstrated that a change in the nature of organic matter and/or its complexing capacity also needed to be taken into consideration. PMID:19646578

  7. Traumatic axonal injury and persistent emotional lability in an adolescent following moderate traumatic brain injury: A case study.

    PubMed

    Henry, Luke C; Burkhart, Scott O; Elbin, R J; Agarwal, Vikus; Kontos, Anthony P

    2015-05-01

    A 15-year-old male was treated secondary to sustaining a moderate traumatic brain injury (moderate TBI). Symptom self-report, and computerized and paper-and-pencil-based neurocognitive, vestibular/ocular motor, and imaging data were used throughout to document impairment and recovery. The patient demonstrated persistent emotional lability concurrent with vestibular impairment. In addition to clinical evaluation and management, the patient also underwent susceptibility-weighted imaging, which revealed axonal shearing across the corpus callosum and areas innervating the prefrontal cortex. Paper-and-pencil neurocognitive measures revealed persisting deficits, despite normal-appearing computerized test results. Implications of this case underline the importance of an integrative evaluation process including clinical interview, neurocognitive and vestibular/ocular physical therapy, and advanced neuroimaging, especially in cases with atypical presentation. PMID:26000663

  8. The unfolding story of anthrax toxin translocation.

    PubMed

    Thoren, Katie L; Krantz, Bryan A

    2011-05-01

    The essential cellular functions of secretion and protein degradation require a molecular machine to unfold and translocate proteins either across a membrane or into a proteolytic complex. Protein translocation is also critical for microbial pathogenesis, namely bacteria can use translocase channels to deliver toxic proteins into a target cell. Anthrax toxin (Atx), a key virulence factor secreted by Bacillus anthracis, provides a robust biophysical model to characterize transmembrane protein translocation. Atx is comprised of three proteins: the translocase component, protective antigen (PA) and two enzyme components, lethal factor (LF) and oedema factor (OF). Atx forms an active holotoxin complex containing a ring-shaped PA oligomer bound to multiple copies of LF and OF. These complexes are endocytosed into mammalian host cells, where PA forms a protein-conducting translocase channel. The proton motive force unfolds and translocates LF and OF through the channel. Recent structure and function studies have shown that LF unfolds during translocation in a force-dependent manner via a series of metastable intermediates. Polypeptide-binding clamps located throughout the PA channel catalyse substrate unfolding and translocation by stabilizing unfolding intermediates through the formation of a series of interactions with various chemical groups and ?-helical structure presented by the unfolding polypeptide during translocation. PMID:21443527

  9. Therapeutic Use of Botulinum Toxin in Neurorehabilitation

    PubMed Central

    Intiso, Domenico

    2012-01-01

    The botulinum toxins (BTX), type A and type B by blocking vesicle acetylcholine release at neuro-muscular and neuro-secretory junctions can result efficacious therapeutic agents for the treatment of numerous disorders in patients requiring neuro-rehabilitative intervention. Its use for the reduction of focal spasticity following stroke, brain injury, and cerebral palsy is provided. Although the reduction of spasticity is widely demonstrated with BTX type A injection, its impact on the improvement of dexterity and functional outcome remains controversial. The use of BTX for the rehabilitation of children with obstetrical brachial plexus palsy and in treating sialorrhea which can complicate the course of some severe neurological diseases such as amyotrophic lateral sclerosis and Parkinson's disease is also addressed. Adverse events and neutralizing antibodies formation after repeated BTX injections can occur. Since impaired neurological persons can have complex disabling feature, BTX treatment should be viewed as adjunct measure to other rehabilitative strategies that are based on the individual's residual ability and competence and targeted to achieve the best functional recovery. BTX therapy has high cost and transient effect, but its benefits outweigh these disadvantages. Future studies must clarify if this agent alone or adjunctive to other rehabilitative procedures works best on functional outcome. PMID:21941544

  10. Persistent Long-Term Facilitation at an Identified Synapse Becomes Labile with Activation of Short-Term Heterosynaptic Plasticity

    PubMed Central

    Schacher, Samuel

    2014-01-01

    Short-term and long-term synaptic plasticity are cellular correlates of learning and memory of different durations. Little is known, however, how these two forms of plasticity interact at the same synaptic connection. We examined the reciprocal impact of short-term heterosynaptic or homosynaptic plasticity at sensorimotor synapses of Aplysia in cell culture when expressing persistent long-term facilitation (P-LTF) evoked by serotonin [5-hydroxytryptamine (5-HT)]. Short-term heterosynaptic plasticity induced by 5-HT (facilitation) or the neuropeptide FMRFa (depression) and short-term homosynaptic plasticity induced by tetanus [post-tetanic potentiation (PTP)] or low-frequency stimulation [homosynaptic depression (HSD)] of the sensory neuron were expressed in both control synapses and synapses expressing P-LTF in the absence or presence of protein synthesis inhibitors. All forms of short-term plasticity failed to significantly affect ongoing P-LTF in the absence of protein synthesis inhibitors. However, P-LTF reversed to control levels when either 5-HT or FMRFa was applied in the presence of rapamycin. In contrast, P-LTF was unaffected when either PTP or HSD was evoked in the presence of either rapamycin or anisomycin. These results indicate that synapses expressing persistent plasticity acquire a “new” baseline and functionally express short-term changes as naive synapses, but the new baseline becomes labile following selective activations—heterosynaptic stimuli that evoke opposite forms of plasticity—such that when presented in the presence of protein synthesis inhibitors produce a rapid reversal of the persistent plasticity. Activity-selective induction of a labile state at synapses expressing persistent plasticity may facilitate the development of therapies for reversing inappropriate memories. PMID:24695698

  11. Pteris vittata continuously removed arsenic from non-labile fraction in three contaminated-soils during 3.5 years of phytoextraction.

    PubMed

    Lessl, Jason T; Luo, Jun; Ma, Lena Q

    2014-08-30

    We evaluated the effectiveness of arsenic (As) hyperaccumulator Pteris vittata to continuously remove As from three contaminated-soils containing 26-126mgkg(-1) As over 7 harvests in 3.5 years. Changes in As speciation in soils, amended with P fertilizer (P-soil) or insoluble phosphate rock (PR-soil), were assessed via sequential fractionation. Arsenic in available (soluble+exchangeable), non-labile (bound to amorphous+crystalline Fe/Al oxides), and residual fractions constituted ?12%, ?80%, and ?8% of soil As. Soluble As declined while exchangeable As was unchanged, likely due to replenishment from non-labile As, which accounted for ?87% of decline in total soil As. Although plant-available As is important, the non-labile As better predicted the frond As concentration in P. vittata, with the correlation being r=0.90 and 0.64 for PR-soils and P-soils. P. vittata removed 44% of soil As from PR-soils compared to 33% from P-soils, suggesting the low-soluble P from PR was more effective than P fertilizer in enhancing As uptake by P. vittata. To facilitate acquisition of P from PR, P. vittata produced larger root biomass to solubilize non-labile As, allowing for more efficient phytoextraction. PMID:25108101

  12. Reproductive and vegetative responses of different accessions of Microlaena stipoides (Labill.) R.Br. to nitrogen applications and supplementary irrigation in southern Australia

    Microsoft Academic Search

    I. H. ChiversA; D. E. AldousB

    2005-01-01

    Native grasses such as Microlaena stipoides (Labill.) R.Br. have the potential to play an important role in pastures, revegetation and as turfgrasses, but their use to date has been limited by seed supply. The purpose of this study was to investigate, (i) the effect of nitrogen fertilisation on M. stipoides seed production, (ii) the effect of irrigation on seed production,

  13. Organic matter recycling in a shallow coastal zone (NW Mediterranean): The influence of local and global climatic forcing and organic matter lability on hydrolytic enzyme activity

    Microsoft Academic Search

    Cristina Misic; Anabella Covazzi Harriague

    2008-01-01

    Seawater and sediment were collected on a monthly basis from a shallow (10.5m depth) coastal site in the Ligurian Sea (NW Mediterranean) from November 1993 to December 1994 to determine the main environmental forces that influenced the biogeochemical processes and to study the relationships between the availability and lability of the organic matter (OM) and hydrolytic enzymatic activity. The current

  14. EFFECTS OF CLIMATE CHANGE ON LABILE AND STRUCTURAL CARBON IN DOUGLAS-FIR NEEDLES AS ESTIMATED BY DELTA 13C AND C AREA MEASUREMENTS

    EPA Science Inventory

    Isotopic measurements may provide new insights into levels in leaves of labile and structural carbon (C) under climate change. In a 4-year climate change experiment using Pseudotsuga menziesii (Douglas-fir) seedlings and a 2x2 factorial design in enclosed chambers (n=3), atmosph...

  15. Modification of opiate agonist binding by pertussis toxin

    SciTech Connect

    Abood, M.E.; Lee, N.M.; Loh, H.H.

    1986-03-05

    Opiate agonist binding is decreased by GTP, suggesting the possible involvement of GTP binding proteins in regulation of opiate receptor binding. This possibility was addressed by asking whether pertussis toxin treatment, which results in ADP-ribosylation and modification of G proteins, would alter opiate agonist binding. The striatum was chosen for the initial brain area to be studied, since regulation of opiate action in this area had been shown to be modified by pertussis toxin. Treatment of striatal membranes with pertussis toxin results in up to a 55% decrease in /sup 3/(H)-DADLE binding as compared with membranes treated identically without toxin. This corresponds to a near complete ADP-ribosylation of both G proteins in the striatal membrane. The decrease in agonist binding appears to be due to an altered affinity of the receptor for agonist as opposed to a decrease in the number of sites. This effect of pertussis toxin on opiate agonist binding demonstrates the actual involvement of G proteins in regulation of opiate receptor binding.

  16. Treatment of Palatal Myoclonus with Botulinum Toxin Injection

    PubMed Central

    Anis, Mursalin M.; Pollak, Natasha

    2013-01-01

    Palatal myoclonus is a rare cause of pulsatile tinnitus in patients presenting to the otolaryngology office. Rhythmic involuntary contractions of the palatal muscles produce the pulsatile tinnitus in these patients. Treatment of this benign but distressing condition with anxiolytics, anticonvulsants, and surgery has been largely unsuccessful. A few investigators have obtained promising results with botulinum toxin injection into the palatal muscles. We present a patient with palatal myoclonus who failed conservative treatment with anxiolytics. Unilateral injection of botulinum toxin into her tensor veli palatini muscle under electromyographic guidance resolved pulsatile tinnitus in her ipsilateral ear and unmasked pulsatile tinnitus in the contralateral ear. A novel method of following transient postinjection symptoms using a diary is presented in this study. Botulinum toxin dose must be titrated to achieve optimal results in each individual patient, analogous to titrations done for spasmodic dysphonia. Knowledge of the temporal onset of postinjection side effects and symptomatic relief may aid physicians in dose titration and surveillance. We present suggestions on titrating the botulinum toxin dose to optimal levels. A review of the literature on the use of botulinum toxin for palatal myoclonus and some common complications are discussed. PMID:24223317

  17. Binding Affinity of Glycoconjugates to BACILLUS Spores and Toxins

    NASA Astrophysics Data System (ADS)

    Rasol, Aveen; Eassa, Souzan; Tarasenko, Olga

    2010-04-01

    Early recognition of Bacillus cereus group species is important since they can cause food-borne illnesses and deadly diseases in humans. Glycoconjugates (GCs) are carbohydrates covalently linked to non-sugar moieties including lipids, proteins or other entities. GCs are involved in recognition and signaling processes intrinsic to biochemical functions in cells. They also stimulate cell-cell adhesion and subsequent recognition and activation of receptors. We have demonstrated that GCs are involved in Bacillus cereus spore recognition. In the present study, we have investigated whether GCs possess the ability to bind and recognize B. cereus spores and Bacillus anthracis recombinant single toxins (sTX) and complex toxins (cTX). The affinity of GCs to spores + sTX and spores + cTX toxins was studied in the binding essay. Our results demonstrated that GC9 and GC10 were able to selectively bind to B. cereus spores and B. anthracis toxins. Different binding affinities for GCs were found toward Bacillus cereus spores + sTX and spores + cTX. Dilution of GCs does not impede the recognition and binding. Developed method provides a tool for simultaneous recognition and targeting of spores, bacteria toxins, and/or other entities.

  18. Channel-Forming Bacterial Toxins in Biosensing and Macromolecule Delivery

    PubMed Central

    Gurnev, Philip A.; Nestorovich, Ekaterina M.

    2014-01-01

    To intoxicate cells, pore-forming bacterial toxins are evolved to allow for the transmembrane traffic of different substrates, ranging from small inorganic ions to cell-specific polypeptides. Recent developments in single-channel electrical recordings, X-ray crystallography, protein engineering, and computational methods have generated a large body of knowledge about the basic principles of channel-mediated molecular transport. These discoveries provide a robust framework for expansion of the described principles and methods toward use of biological nanopores in the growing field of nanobiotechnology. This article, written for a special volume on “Intracellular Traffic and Transport of Bacterial Protein Toxins”, reviews the current state of applications of pore-forming bacterial toxins in small- and macromolecule-sensing, targeted cancer therapy, and drug delivery. We discuss the electrophysiological studies that explore molecular details of channel-facilitated protein and polymer transport across cellular membranes using both natural and foreign substrates. The review focuses on the structurally and functionally different bacterial toxins: gramicidin A of Bacillus brevis, ?-hemolysin of Staphylococcus aureus, and binary toxin of Bacillus anthracis, which have found their “second life” in a variety of developing medical and technological applications. PMID:25153255

  19. THE RESPONSE OF CULTURED MAMMALIAN CELLS TO DIPHTHERIA TOXIN

    PubMed Central

    Moehring, Thomas J.; Moehring, Joan M.; Kuchler, Robert J.; Solotorovsky, Morris

    1967-01-01

    The response to diphtheria toxin of two sensitive cell lines, KB and HeLa, was investigated. Inhibition of the incorporation of radioactively labeled amino acids into protein was the earliest detectable effect of diphtheria toxin. It was observed that, during the period of intoxication, the cell membrane was morphologically intact and retained its semi-permeable character, although it was rendered fragile and more easily disrupted by mechanical manipulations than the normal cell. The transport of amino acids continued even after intoxicated cells had ceased to synthesize protein, and the levels accumulated were equal to those of control cells. It was observed that cultural conditions, age, and handling of cells affected their response to toxin. In early log phase cells subjected to a minimum of handling before application of the toxin, the normally observed latent period preceding detectable effects was reduced to 15 min for KB cells and 30 min for HeLa cells, shorter times than previously reported. The data are consistent with the hypothesis that diphtheria toxin enters susceptible cells, possibly by pinocytosis, and there acts upon cytoplasmic sites of protein synthesis. PMID:5340609

  20. Isolation of isoelectrically pure cholera toxin for crystallization

    SciTech Connect

    Spangler, B.D.; Westbrook, E.M.

    1989-01-01

    We have determined that the failure of cholera toxin to crystallize well results from its isoelectric heterogeneity, which is probably due to a post-translational process such as deamidation of its B subunit. Every sample of cholera toxin we have examined from commercial or academic suppliers has been heterogeneous; heterogeneous cholera toxin does not crystallize satisfactorily. We have overcome this problem by using ion-exchange fast protein liquid chromatography (FPLC) to obtain an isoelectrically homogeneous species of cholera toxin. Homogeneous cholera toxin crystallizes readily, forming single, nonmosaic crystals suitable for x-ray diffraction studies. For this process, protein was applied to a MonoQ ion-exchange column, then eluted with an isocratic low salt buffer followed by a linear salt gradient (0-100 mM NaCl). Column fractions were analyzed on isoelectric focusing gels, and those fractions containing the desired homogeneous species were pooled and concentrated. Crystals formed within 24 to 48 hours in a MOPS/PEG buffer, which made use of slow isoelectric precipitation to induce crystallization. 23 refs., 6 figs.

  1. SNARE tagging allows stepwise assembly of a multimodular medicinal toxin

    PubMed Central

    Darios, Frédéric; Niranjan, Dhevahi; Ferrari, Enrico; Zhang, Fan; Soloviev, Mikhail; Rummel, Andreas; Bigalke, Hans; Suckling, Jason; Ushkaryov, Yuri; Naumenko, Nikolay; Shakirzyanova, Anastasia; Giniatullin, Rashid; Maywood, Elizabeth; Hastings, Michael; Binz, Thomas; Davletov, Bazbek

    2010-01-01

    Generation of supramolecular architectures through controlled linking of suitable building blocks can offer new perspectives to medicine and applied technologies. Current linking strategies often rely on chemical methods that have limitations and cannot take full advantage of the recombinant technologies. Here we used SNARE proteins, namely, syntaxin, SNAP25, and synaptobrevin, which form stable tetrahelical complexes that drive fusion of intracellular membranes, as versatile tags for irreversible linking of recombinant and synthetic functional units. We show that SNARE tagging allows stepwise production of a functional modular medicinal toxin, namely, botulinum neurotoxin type A, commonly known as BOTOX. This toxin consists of three structurally independent units: Receptor-binding domain (Rbd), Translocation domain (Td), and the Light chain (Lc), the last being a proteolytic enzyme. Fusing the receptor-binding domain with synaptobrevin SNARE motif allowed delivery of the active part of botulinum neurotoxin (Lc-Td), tagged with SNAP25, into neurons. Our data show that SNARE-tagged toxin was able to cleave its intraneuronal molecular target and to inhibit release of neurotransmitters. The reassembled toxin provides a safer alternative to existing botulinum neurotoxin and may offer wider use of this popular research and medical tool. Finally, SNARE tagging allowed the Rbd portion of the toxin to be used to deliver quantum dots and other fluorescent markers into neurons, showing versatility of this unique tagging and self-assembly technique. Together, these results demonstrate that the SNARE tetrahelical coiled-coil allows controlled linking of various building blocks into multifunctional assemblies. PMID:20921391

  2. Toxins not neutralized by brown snake antivenom

    SciTech Connect

    Judge, Roopwant K. [Molecular Genetics and Evolution Group, Research School of Biological Sciences, Australian National University, Canberra 2601, ACT (Australia); Henry, Peter J. [School of Medicine and Pharmacology, University of Western Australia, Crawley 6009, Western Australia (Australia); Mirtschin, Peter [Venom Supplies, Tanunda 5352, South Australia (Australia); Jelinek, George [School of Primary, Aboriginal and Rural Health Care, QEII Medical Centre, Western Australia (Australia); Wilce, Jacqueline A. [Department of Biochemistry and Molecular Biology, Monash University, Clayton 3800, VIC Victoria (Australia)]. E-mail: Jackie.Wilce@med.monash.edu.au

    2006-06-01

    The Australian snakes of the genus Pseudonaja (dugite, gwardar and common brown) account for the majority of snake bite related deaths in Australia. Without antivenom treatment, the risk of mortality is significant. There is an accumulating body of evidence to suggest that the efficacy of the antivenom is limited. The current study investigates the protein constituents recognized by the antivenom using 2-DE, immuno-blot techniques and rat tracheal organ bath assays. The 2-DE profiles for all three snake venoms were similar, with major species visualized at 78-132 kDa, 32-45 kDa and 6-15 kDa. Proteins characterized by LC-MS/MS revealed a coagulant toxin ({approx}42 kDa) and coagulant peptide ({approx}6 kDa), as well as two PLA{sub 2} ({approx}14 kDa). Peptides isolated from {approx}78 kDa and 15-32 kDa protein components showed no similarity to known protein sequences. Protein recognition by the antivenom occurred predominantly for the higher molecular weight components with little recognition of 6-32 kDa MW species. The ability of antivenom to neutralize venom activity was also investigated using rat tracheal organ bath assays. The venoms of Pseudonaja affinis affinis and Pseudonaja nuchalis incited a sustained, significant contraction of the trachea. These contractions were attributed to PLA{sub 2} enzymatic activity as pre-treatment with the PLA{sub 2} inhibitor 4-BPB attenuated the venom-induced contractions. The venom of Pseudonaja textilis incited tracheal contractility through a non-PLA{sub 2} enzymatic activity. Neither activity was attenuated by the antivenom treatment. These results represent the first proteomic investigation of the venoms from the snakes of the genus Pseudonaja, revealing a possible limitation of the brown snake antivenom in binding to the low MW protein components.

  3. FDA Approves First Botulism Antitoxin for Use in Neutralizing All Seven Known Botulinum Nerve Toxin Serotypes

    MedlinePLUS

    ... approves first Botulism Antitoxin for use in neutralizing all seven known botulinum nerve toxin serotypes Product to ... contains a mixture of antibody fragments that neutralize all of the seven botulinum nerve toxin serotypes known ...

  4. Retrograde transport of cholera toxin from the plasma membrane to the endoplasmic reticulum requires

    E-print Network

    Kirchhausen, Tomas

    . Keywords: chemical genetics; membrane traffic; phenotypic screen; toxin EMBO reports (2004) 5, 596­601. doi). The B-subunit co-opts ganglioside GM1, a plasma membrane (PM) glycolipid, that carries the toxin all

  5. 9 CFR 121.10 - Restricting access to select agents and toxins; security risk assessments.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ...PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE VIRUSES, SERUMS, TOXINS, AND ANALOGOUS PRODUCTS; ORGANISMS AND VECTORS POSSESSION, USE, AND TRANSFER OF SELECT AGENTS AND TOXINS § 121.10 Restricting access to select agents and...

  6. Prevalence and pathogenicity of binary toxin–positive Clostridium difficile strains that do not produce toxins A and B

    PubMed Central

    Eckert, C.; Emirian, A.; Le Monnier, A.; Cathala, L.; De Montclos, H.; Goret, J.; Berger, P.; Petit, A.; De Chevigny, A.; Jean-Pierre, H.; Nebbad, B.; Camiade, S.; Meckenstock, R.; Lalande, V.; Marchandin, H.; Barbut, F.

    2014-01-01

    Clostridium difficile causes antibiotic-associated diarrhoea and pseudomembranous colitis. The main virulence factors of C. difficile are the toxins A (TcdA) and B (TcdB). A third toxin, called binary toxin (CDT), can be detected in 17% to 23% of strains, but its role in human disease has not been clearly defined. We report six independent cases of patients with diarrhoea suspected of having C. difficile infection due to strains from toxinotype XI/PCR ribotype 033 or 033-like, an unusual toxinotype/PCR ribotype positive for CDT but negative for TcdA and TcdB. Four patients were considered truly infected by clinicians and were specifically treated with oral metronidazole. One of the cases was identified during a prevalence study of A?B?CDT+ strains. In this study, we screened a French collection of 220 nontoxigenic strains and found only one (0.5%) toxinotype XI/PCR ribotype 033 or 033-like strain. The description of such strains raises the question of the role of binary toxin as a virulence factor and could have implications for laboratory diagnostics that currently rarely include testing for binary toxin. PMID:25755885

  7. Vibrio vulnificus Biotype 3 Multifunctional Autoprocessing RTX Toxin Is an Adenylate Cyclase Toxin Essential for Virulence in Mice

    PubMed Central

    Ziolo, Kevin J.; Jeong, Hee-Gon; Kwak, Jayme S.; Yang, Shuangni; Lavker, Robert M.

    2014-01-01

    Vibrio vulnificus is an environmental organism that causes both food-borne and wound infections with high morbidity and mortality in humans. The annual incidence and global distribution of infections associated with this pathogen are increasing with climate change. In the late 1990s, an outbreak of tilapia-associated wound infections in Israel was linked to a previously unrecognized variant of V. vulnificus designated biotype 3. The sudden emergence and clonality of the outbreak suggest that this strain may be a true newly emergent pathogen with novel virulence properties compared to those of other V. vulnificus strains. In a subcutaneous infection model to mimic wound infection, the multifunctional autoprocessing RTX (MARTX) toxin of biotype 3 strains was shown to be an essential virulence factor contributing to highly inflammatory skin wounds with severe damage affecting every tissue layer. We conducted a sequencing-based analysis of the MARTX toxin and found that biotype 3 MARTX toxin has an effector domain structure distinct from that of either biotype 1 or biotype 2. Of the two new domains identified, a domain similar to Pseudomonas aeruginosa ExoY was shown to confer adenylate cyclase activity on the MARTX toxin. This is the first demonstration that the biotype 3 MARTX toxin is essential for virulence and that the ExoY-like MARTX effector domain is a catalytically active adenylate cyclase. PMID:24614656

  8. Does expression of Bt toxin matter in farmer's pesticide use?

    PubMed

    Huang, Jikun; Chen, Ruijian; Qiao, Fangbin; Su, Honghua; Wu, Kongming

    2014-05-01

    Despite the widespread adoption of Bt cotton, farmers still spray excessive pesticides in their cotton fields. In contrast to scientists who always use high quality seeds in the laboratory and/or experimental fields, farmers may plant low quality seeds with a low expression of Bt toxin. How does the expression of Bt toxin influence farmers' pesticide use? On the basis of a plot-level survey and laboratory test data, this study shows that pesticide use on one cotton plot is influenced not only by the expression of Bt crops in this plot, but also by the average expression in the village in the early stage of the cotton growing season. In other words, high expression of Bt toxin benefits not only the farmers who plant the varieties but also all the other villagers. PMID:24702829

  9. Effectiveness of Botulinum Toxin Administered to Abolish Acquired Nystagmus

    NASA Technical Reports Server (NTRS)

    Leigh, R. John; Tomsak, Robert L.; Grant, Michael P.; Remler, Bernd F.; Yaniglos, Stacy S.; Lystad, Lisa; Dell'Osso, Louis F.

    1992-01-01

    We injected botulinum toxin into the horizontal rectus muscles of the right eyes of two patients who had acquired pendular nystagmus with horizontal, vertical, and torsional components. This treatment successfully abolished the horizontal component of the nystagmus in the injected eye in both patients for approximately 2 months. Both patients showed a small but measurable improvement of vision in the injected eye that may have been limited by coexistent disease of the visual pathways. The vertical and torsional components of the nystagmus persisted in both patients. In one patient, the horizontal component of nystagmus in the noninjected eye increased; we ascribe this finding to plastic-adaptive changes in response to paresis caused by the botulinum toxin. Such plastic-adaptive changes and direct side effects of the injections - such as diplopia and ptosis - may limit the effectiveness of botulinum toxin in the treatment of acquired nystagmus. Neither patient elected to repeat the botulinum treatment.

  10. Histone modifications induced by a family of bacterial toxins

    PubMed Central

    Hamon, Mélanie Anne; Batsché, Eric; Régnault, Béatrice; Tham, To Nam; Seveau, Stéphanie; Muchardt, Christian; Cossart, Pascale

    2007-01-01

    Upon infection, pathogens reprogram host gene expression. In eukaryotic cells, genetic reprogramming is induced by the concerted activation/repression of transcription factors and various histone modifications that control DNA accessibility in chromatin. We report here that the bacterial pathogen Listeria monocytogenes induces a dramatic dephosphorylation of histone H3 as well as a deacetylation of histone H4 during early phases of infection. This effect is mediated by the major listerial toxin listeriolysin O in a pore-forming-independent manner. Strikingly, a similar effect also is observed with other toxins of the same family, such as Clostridium perfringens perfringolysin and Streptococcus pneumoniae pneumolysin. The decreased levels of histone modifications correlate with a reduced transcriptional activity of a subset of host genes, including key immunity genes. Thus, control of epigenetic regulation emerges here as an unsuspected function shared by several bacterial toxins, highlighting a common strategy used by intracellular and extracellular pathogens to modulate the host response early during infection. PMID:17675409

  11. Mechanism of Tryptic Activation of Clostridium botulinum Type E Toxin

    PubMed Central

    Gerwing, Julia; Dolman, Claude E.; Ko, Arthur

    1965-01-01

    Gerwing, Julia (University of British Columbia, Vancouver, B.C., Canada), Claude E. Dolman, and Arthur Ko. Mechanism of tryptic activation of Clostridium botulinum type E toxin. J. Bacteriol. 89:1176–1179. 1965.—The toxic peptide of trypsin activated Clostridium botulinum type E toxin was purified by chromatography through columns packed with Sephadex G-75 and G-50. The molecular weight of the active peptide was estimated to lie between 10,000 and 12,000. Amino acid analyses indicated that the active peptide had lost at least 18 of the amino acid residues present in the original protein. The active peptide and the original protein were found to have different N-terminal amino acid residues. The mechanism of tryptic activation apparently involves chiefly the removal of amino acids from the N-terminus of the toxin molecule. PMID:14292982

  12. Treatment of displaced mandibular condylar fracture with botulinum toxin A.

    PubMed

    Akbay, Ercan; Cevik, Cengiz; Damlar, Ibrahim; Altan, Ahmet

    2014-04-01

    The aim of this case report is to discuss the effect on condylar reduction of botulinum toxin A treatment used in a child with displaced fracture at condylar neck of mandible. A 3-years old boy was admitted to our clinic for incomplete fracture of mandibular symphysis and displaced condylar fracture at the left side. An asymmetrical occlusal splint with intermaxillary fixation was used instead of open reduction and internal fixation because of incomplete fracture of symphysis and possible complications of condyle surgery. However, it was observed that condylar angulation persisted despite this procedure. Thus, botulinum toxin A was administered to masseter, temporalis and pterygoideus medialis muscles. At the end of first month, it was seen that mandibular condyle was almost completely recovered and that fusion was achieved. In conclusion, Botulinum A toxin injection aiming the suppression of masticatory muscle strength facilitates the reduction in the conservative management of displaced condyle in pediatric patients. PMID:24156980

  13. Cigarette Smoke, Bacteria, Mold, Microbial Toxins, and Chronic Lung Inflammation

    PubMed Central

    Pauly, John L.; Paszkiewicz, Geraldine

    2011-01-01

    Chronic inflammation associated with cigarette smoke fosters malignant transformation and tumor cell proliferation and promotes certain nonneoplastic pulmonary diseases. The question arises as to whether chronic inflammation and/or colonization of the airway can be attributed, at least in part, to tobacco-associated microbes (bacteria, fungi, and spores) and/or microbial toxins (endotoxins and mycotoxins) in tobacco. To address this question, a literature search of documents in various databases was performed. The databases included PubMed, Legacy Tobacco Documents Library, and US Patents. This investigation documents that tobacco companies have identified and quantified bacteria, fungi, and microbial toxins at harvest, throughout fermentation, and during storage. Also characterized was the microbial flora of diverse smoking and smokeless tobacco articles. Evidence-based health concerns expressed in investigations of microbes and microbial toxins in cigarettes, cigarette smoke, and smokeless tobacco products are reasonable; they warrant review by regulatory authorities and, if necessary, additional investigation to address scientific gaps. PMID:21772847

  14. The Glucocorticoid Receptor: A Revisited Target for Toxins

    PubMed Central

    Marketon, Jeanette I. Webster; Sternberg, Esther M.

    2010-01-01

    The hypothalamic-pituitary-adrenal (HPA) axis activation and glucocorticoid responses are critical for survival from a number of bacterial, viral and toxic insults, demonstrated by the fact that removal of the HPA axis or GR blockade enhances mortality rates. Replacement with synthetic glucocorticoids reverses these effects by providing protection against lethal effects. Glucocorticoid resistance/insensitivity is a common problem in the treatment of many diseases. Much research has focused on the molecular mechanism behind this resistance, but an area that has been neglected is the role of infectious agents and toxins. We have recently shown that the anthrax lethal toxin is able to repress glucocorticoid receptor function. Data suggesting that the glucocorticoid receptor may be a target for a variety of toxins is reviewed here. These studies have important implications for glucocorticoid therapy. PMID:22069642

  15. Cholera toxin can catalyze ADP-ribosylation of cytoskeletal proteins

    SciTech Connect

    Kaslow, H.R.; Groppi, V.E.; Abood, M.E.; Bourne, H.R.

    1981-11-01

    Cholera toxin catalyzes transfer of radiolabel from (/sup 32/P)NAD/sup +/ to several peptides in particulate preparations of human foreskin fibroblasts. Resolution of these peptides by two-dimensional gel electrophoresis allowed identification of two peptides of M/sub r/ = 42,000 and 52,000 as peptide subunits of a regulatory component of adenylate cyclase. The radiolabeling of another group of peptides (M/sub r/ = 50,000 to 65,000) suggested that cholera toxin could catalyze ADP-ribosylation of cytoskeletal proteins. This suggestion was confirmed by showing that incubation with cholera toxin and (/sup 32/P)NAD/sup +/ caused radiolabeling of purified microtubule and intermediate filament proteins.

  16. Uremic toxins, oxidative stress, and renal fibrosis: an interwined complex.

    PubMed

    Chao, Chia-Ter; Chiang, Chih-Kang

    2015-03-01

    The prevalence of end-stage renal diseases is currently on the rise globally, and finding the way to curb this tide is urgently needed. Tubulointerstitial fibrosis is a common pathway for essentially all the nephropathy categories known to date, and the manifestations of renal fibrosis include excessive deposition of extracellular matrix with distortion of renal microstructures and functional deterioration. Uremic toxins have been gradually found to play an important role in the development of progressive renal fibrosis, with protein-bound indoxyl sulfate, p-cresol, and p-cresyl sulfate receiving the most attention. However, the contribution of oxidative stress among the pathogenesis of uremic toxins and renal fibrosis has not been evaluated much until recently. In this review, we will discuss about the nature and sources of oxidative stress in the kidney and how uremic toxins use oxidative stress to orchestrate the processes of renal fibrosis. PMID:25511523

  17. Direct Inhibition of T-Lymphocyte Activation by Anthrax Toxins In Vivo

    Microsoft Academic Search

    Jason E. Comer; Ashok K. Chopra; Johnny W. Peterson; Rolf Konig

    2005-01-01

    Received 28 June 2005\\/Returned for modification 4 September 2005\\/Accepted 18 September 2005 The causative agent of anthrax, Bacillus anthracis, produces two toxins that contribute in part to its virulence. Lethal toxin is a metalloprotease that cleaves upstream mitogen-activated protein kinase kinases. Edema toxin is a calmodulin-dependent adenylate cyclase. Previous studies demonstrated that the anthrax toxins are important immunomodulators that promote

  18. Endosomal recycling regulates anthrax toxin receptor 1\\/tumor endothelial marker 8-dependent cell spreading

    Microsoft Academic Search

    Jingsheng Gu; Victor Faundez; Erica Werner

    2010-01-01

    Mechanisms for receptor-mediated anthrax toxin internalization and delivery to the cytosol are well understood. However, far less is known about the fate followed by anthrax toxin receptors prior and after cell exposure to the toxin. We report that Anthrax Toxin Receptor 1\\/Tumor Endothelial Marker 8 (TEM8) localized at steady state in Rab11a-positive and transferrin receptor-containing recycling endosomes. TEM8 followed a

  19. Production in vitro of the Toxin of Bacillus anthracis Previously Recognized in vivo

    Microsoft Academic Search

    PATRICIA W. HARRIS-SMITH; H. Smith; J. Keppie

    1958-01-01

    SUMMARY: A lethal oedema-producing toxin has been made in vitm in serum cultures of Bacillus anthracis which is identical with the toxin originally recognized in Wiuo. Toxin is produced by the attenuated immunogenic Sterne strain as well as by the virulent N.P. strain. Previous non-recognition of the toxin in cultures was due to its early appearance and rapid disappearance under

  20. Characterization of Toxin-Producing Cyanobacteria by Using an Oligonucleotide Probe Containing a Tandemly Repeated Heptamer

    Microsoft Academic Search

    LEO ROUHIAINEN; KAARINA SIVONEN; WILLIAM J. BUIKEMA; ANDROBERT HASELKORN

    1995-01-01

    Cyanobacteria produce toxins that kill animals. The two main classes of cyanobacterial toxins are cyclic peptides that cause liver damage and alkaloids that block nerve transmission. Many toxin-producing strains from Finnish lakes were brought into axenic culture, and their toxins were characterized. Restriction fragment lengthpolymorphismanalysis,probingwithashorttandemlyrepeatedDNAsequencefoundatmanylocations in the chromosome of Anabaena sp. strain PCC 7120, distinguishes hepatotoxic Anabaena isolates from neurotoxin-producing

  1. Transition State Structure for ADP-Ribosylation of Eukaryotic Elongation Factor 2 Catalyzed by Diphtheria Toxin

    Microsoft Academic Search

    Sapan L. Parikh; Vern L. Schramm

    2004-01-01

    Bacterial protein toxins are the most powerful human poisons known, exhibiting an LD50 of 0.1- 1n g kg -1. A major subset of such toxins is the NAD+-dependent ADP-ribosylating exotoxins, which include pertussis, cholera, and diphtheria toxin. Diphtheria toxin catalyzes the ADP ribosylation of the diphthamide residue of eukaryotic elongation factor 2 (eEF-2). The transition state of ADP ribosylation catalyzed

  2. Aedes aegypti Mos20 cells internalizes cry toxins by endocytosis, and actin has a role in the defense against Cry11Aa toxin.

    PubMed

    Vega-Cabrera, Adriana; Cancino-Rodezno, Angeles; Porta, Helena; Pardo-Lopez, Liliana

    2014-02-01

    Bacillus thuringiensis (Bt) Cry toxins are used to control Aedes aegypti, an important vector of dengue fever and yellow fever. Bt Cry toxin forms pores in the gut cells, provoking larvae death by osmotic shock. Little is known, however, about the endocytic and/or degradative cell processes that may counteract the toxin action at low doses. The purpose of this work is to describe the mechanisms of internalization and detoxification of Cry toxins, at low doses, into Mos20 cells from A. aegypti, following endocytotic and cytoskeletal markers or specific chemical inhibitors. Here, we show that both clathrin-dependent and clathrin-independent endocytosis are involved in the internalization into Mos20 cells of Cry11Aa, a toxin specific for Dipteran, and Cry1Ab, a toxin specific for Lepidoptera. Cry11Aa and Cry1Ab are not directed to secretory lysosomes. Instead, Mos20 cells use the Rab5 and Rab11 pathways as a common mechanism, most probably for the expulsion of Cry11Aa and Cry1Ab toxins. In conclusion, we propose that endocytosis is a mechanism induced by Cry toxins independently of specificity, probably as part of a basal immune response. We found, however, that actin is necessary for defense-specific response to Cry11Aa, because actin-silenced Mos20 cells become more sensitive to the toxic action of Cry11A toxin. Cry toxin internalization analysis in insect cell lines may contribute to a better understanding to Cry resistance in mosquitoes. PMID:24476709

  3. Emerging treatments for overactive bladder: clinical potential of botulinum toxins

    PubMed Central

    Tincello, Douglas G; Rashid, Tina; Revicky, Vladimir

    2014-01-01

    Overactive bladder (OAB) is a symptom syndrome including urgency, frequency, and nocturia – with or without incontinence. It is a common manifestation of detrusor overactivity (DO). DO is a urodynamic observation of spontaneous or provoked contractions of the detrusor muscle is seen during the filling phase of the micturition cycle. OAB is, therefore, both a motor and sensory disorder. Botulinum toxin is a purified form of the neurotoxin from Clostridium botulinum and has been used in medicine for many years. Over the last 10 years, it has been used for the treatment of DO and OAB when standard treatments, such as bladder training and oral anticholinergic medication, have failed to provide symptom relief. Botulinum toxin acts by irreversibly preventing neurotransmitter release from the neurons in the motor end plate and also at sensory synapses, although the clinical effect is not permanent due to the growth of new connections within treated tissues. It is known that botulinum toxin modulates vanillioid, purinergic, capsaicin, and muscarinic receptor expression within the lamina propria, returning them to levels seen in normal bladders. Clinically, the effect of botulinum toxin on symptoms of OAB and DO is profound, with large effects upon the symptom of urgency, and also large effects on frequency, nocturia, leakage episodes, and continence rates. These effects have been seen consistently within eight randomized trials and numerous case series. Botulinum toxin appears safe, with the only common side effect being that of voiding difficulty, occurring in up to 10% of treated patients. Dosing regimens are variable, depending on which preparation is used, but it is clear that dose recommendations have fallen over the last 5 years. There is limited evidence about the efficacy of repeat treatments. Botulinum toxin is an effective and safe second-line treatment for patients with OAB and DO. PMID:24892033

  4. Membrane pore architecture of a cytolytic toxin from Bacillus thuringiensis.

    PubMed Central

    Promdonkoy, B; Ellar, D J

    2000-01-01

    To investigate the membrane pore structure of Cyt2Aa1 toxin from Bacillus thuringiensis, 14 single-cysteine substitutions of the toxin were constructed. Five of these mutants (L172C, V186C, L189C, E214C and L220C) yielded characteristic products when processed by proteinase K; other mutants were degraded by this enzyme. Mutants that yielded characteristic proteolysed products and wild-type toxin were labelled with polarity-sensitive acrylodan (6-acryloyl-2-dimethylaminonaphthalene) at the thiol group of cysteine residues. A green-blue shift in the emission spectra was observed with all labelled toxins on transfer from an aqueous solution into a solution containing membranes or liposomes from red blood cells. These results suggested that the label moved into the hydrophobic environment of the membrane or became buried within hydrophobic regions of the protein oligomers. Digestion of membrane-bound labelled toxin with proteinase K did not cause a significant decrease in emission intensity from any of the labelled mutants. This suggests that L172C, V186C, L189C, E214C and L220C are inserted into the membrane and are therefore protected from proteolysis. In contrast, a marked decrease in emission intensity was observed when membrane-bound labelled wild-type toxin was digested with proteinase K. This suggests that Cys-19 does not insert into the membrane. Fluorimetric analysis of delipidated pore complexes suggests that L172C, V186C, L189C and E214C point towards the lipid in the membrane, whereas L220C is either within the hydrophobic environment of the protein oligomers or exposed to the membrane lipids. Most of the Cys-19 from wild-type molecules is enclosed within the hydrophobic pockets of the protein oligomers. PMID:10926854

  5. Toxin Models of Mitochondrial Dysfunction in Parkinson's Disease

    PubMed Central

    Martinez, Terina N.

    2012-01-01

    Abstract Significance: Parkinson's disease (PD) is a neurodegenerative disorder characterized, in part, by the progressive and selective loss of dopaminergic neuron cell bodies within the substantia nigra pars compacta (SNpc) and the associated deficiency of the neurotransmitter dopamine (DA) in the striatum, which gives rise to the typical motor symptoms of PD. The mechanisms that contribute to the induction and progressive cell death of dopaminergic neurons in PD are multi-faceted and remain incompletely understood. Data from epidemiological studies in humans and molecular studies in genetic, as well as toxin-induced animal models of parkinsonism, indicate that mitochondrial dysfunction occurs early in the pathogenesis of both familial and idiopathic PD. In this review, we provide an overview of toxin models of mitochondrial dysfunction in experimental Parkinson's disease and discuss mitochondrial mechanisms of neurotoxicity. Recent Advances: A new toxin model using the mitochondrial toxin trichloroethylene was recently described and novel methods, such as intranasal exposure to toxins, have been explored. Additionally, recent research conducted in toxin models of parkinsonism provides an emerging emphasis on extranigral aspects of PD pathology. Critical Issues: Unfortunately, none of the existing animal models of experimental PD completely mimics the etiology, progression, and pathology of human PD. Future Directions: Continued efforts to optimize established animal models of parkinsonism, as well as the development and characterization of new animal models are essential, as there still remains a disconnect in terms of translating mechanistic observations in animal models of experimental PD into bona fide disease-modifying therapeutics for human PD patients. Antioxid. Redox Signal. 16, 920–934. PMID:21554057

  6. Clostridium difficile Toxins: Mechanism of Action and Role in Disease

    PubMed Central

    Voth, Daniel E.; Ballard, Jimmy D.

    2005-01-01

    As the leading cause of hospital-acquired diarrhea, Clostridium difficile colonizes the large bowel of patients undergoing antibiotic therapy and produces two toxins, which cause notable disease pathologies. These two toxins, TcdA and TcdB, are encoded on a pathogenicity locus along with negative and positive regulators of their expression. Following expression and release from the bacterium, TcdA and TcdB translocate to the cytosol of target cells and inactivate small GTP-binding proteins, which include Rho, Rac, and Cdc42. Inactivation of these substrates occurs through monoglucosylation of a single reactive threonine, which lies within the effector-binding loop and coordinates a divalent cation critical to binding GTP. By glucosylating small GTPases, TcdA and TcdB cause actin condensation and cell rounding, which is followed by death of the cell. TcdA elicits effects primarily within the intestinal epithelium, while TcdB has a broader cell tropism. Important advances in the study of these toxins have been made in the past 15 years, and these are detailed in this review. The domains, subdomains, and residues of these toxins important for receptor binding and enzymatic activity have been elegantly studied and are highlighted herein. Furthermore, there have been major advances in defining the role of these toxins in modulating the inflammatory events involving the disruption of cell junctions, neuronal activation, cytokine production, and infiltration by polymorphonuclear cells. Collectively, the present review provides a comprehensive update on TcdA and TcdB's mechanism of action as well as the role of these toxins in disease. PMID:15831824

  7. A novel approach to detect toxin-catalyzed ADP-ribosylation in intact cells: its use to study the action of Pasteurella multocida toxin

    PubMed Central

    1991-01-01

    Certain microbial toxins are ADP-ribosyltransferases, acting on specific substrate proteins. Although these toxins have been of great utility in studies of cellular regulatory processes, a simple procedure to directly study toxin-catalyzed ADP-ribosylation in intact cells has not been described. Our approach was to use [2-3H]adenine to metabolically label the cellular NAD+ pool. Labeled proteins were then denatured with SDS, resolved by PAGE, and detected by flurography. In this manner, we show that pertussis toxin, after a dose-dependent lag period, [3H]-labeled a 40-kD protein intact cells. Furthermore, incubation of the gel with trichloroacetic acid at 95 degrees C before fluorography caused the release of label from bands other than the pertussis toxin substrate, thus, allowing its selective visualization. The modification of the 40-kD protein was ascribed to ADP-ribosylation of a cysteine residue on the basis of inhibition of labeling by nicotinamide and the release of [3H]ADP-ribose from the labeled protein by mercuric acetate. Cholera toxin catalyzed the [3H]-labeling of a 46- kD protein in the [2-3H]adenine-labeled cells. Pretreatment of the cells with pertussis toxin before the labeling of NAD+ with [2- 3H]adenine blocked [2-3H]ADP-ribosylation catalyzed by pertussis toxin, but not that by cholera toxin. Thus, labeling with [2-3H]adenine permits the study of toxin-catalyzed ADP-ribosylation in intact cells. Pasteurella multocida toxin has recently been described as a novel and potent mitogen for Swiss 3T3 cell and acts to stimulate the phospholipase C-mediated hydrolysis of polyphosphoinositides. The basis of the action of the toxin is not known. Using the methodology described here, P. multocida toxin was not found to act by ADP- ribosylation. PMID:1835459

  8. Role of Shiga/Vero toxins in pathogenesis

    PubMed Central

    Obata, Fumiko; Obrig, Tom

    2014-01-01

    Shiga toxin (Stx) is the primary cause of severe host responses including renal and central nervous system (CNS) disease in Shiga toxin-producing E. coli (STEC) infections. The interaction of Stx with different eukaryotic cell types is described. Host responses to Stx and bacterial lipopolysaccharide (LPS) are compared as related to the features of the STEC-associated Hemolytic Uremic Syndrome (HUS). Data derived from animal models of HUS and CNS disease, in vivo, and eukaryotic cells, in vitro, are evaluated in relation to HUS disease of humans. PMID:25530918

  9. Toxins produced in cyanobacterial water blooms – toxicity and risks

    PubMed Central

    Bláha, Lud?k; Babica, Pavel; Maršálek, Blahoslav

    2009-01-01

    Cyanobacterial blooms in freshwaters represent a major ecological and human health problem worldwide. This paper briefly summarizes information on major cyanobacterial toxins (hepatotoxins, neurotoxins etc.) with special attention to microcystins-cyclic heptapeptides with high acute and chronic toxicities. Besides discussion of human health risks, microcystin ecotoxicology and consequent ecological risks are also highlighted. Although significant research attention has been paid to microcystins, cyanobacteria produce a wide range of currently unknown toxins, which will require research attention. Further research should also address possible additive, synergistic or antagonistic effects among different classes of cyanobacterial metabolites, as well as interactions with other toxic stressors such as metals or persistent organic pollutants. PMID:21217843

  10. Unrelated toxin-antitoxin systems cooperate to induce persistence.

    PubMed

    Fasani, Rick A; Savageau, Michael A

    2015-07-01

    Persisters are drug-tolerant bacteria that account for the majority of bacterial infections. They are not mutants, rather, they are slow-growing cells in an otherwise normally growing population. It is known that the frequency of persisters in a population is correlated with the number of toxin-antitoxin systems in the organism. Our previous work provided a mechanistic link between the two by showing how multiple toxin-antitoxin systems, which are present in nearly all bacteria, can cooperate to induce bistable toxin concentrations that result in a heterogeneous population of slow- and fast-growing cells. As such, the slow-growing persisters are a bet-hedging subpopulation maintained under normal conditions. For technical reasons, the model assumed that the kinetic parameters of the various toxin-antitoxin systems in the cell are identical, but experimental data indicate that they differ, sometimes dramatically. Thus, a critical question remains: whether toxin-antitoxin systems from the diverse families, often found together in a cell, with significantly different kinetics, can cooperate in a similar manner. Here, we characterize the interaction of toxin-antitoxin systems from many families that are unrelated and kinetically diverse, and identify the essential determinant for their cooperation. The generic architecture of toxin-antitoxin systems provides the potential for bistability, and our results show that even when they do not exhibit bistability alone, unrelated systems can be coupled by the growth rate to create a strongly bistable, hysteretic switch between normal (fast-growing) and persistent (slow-growing) states. Different combinations of kinetic parameters can produce similar toxic switching thresholds, and the proximity of the thresholds is the primary determinant of bistability. Stochastic fluctuations can spontaneously switch all of the toxin-antitoxin systems in a cell at once. The spontaneous switch creates a heterogeneous population of growing and non-growing cells, typical of persisters, that exist under normal conditions, rather than only as an induced response. The frequency of persisters in the population can be tuned for a particular environmental niche by mixing and matching unrelated systems via mutation, horizontal gene transfer and selection. PMID:26063817

  11. Anthrax lethal and edema toxins in anthrax pathogenesis

    PubMed Central

    Liu, Shihui; Moayeri, Mahtab; Leppla, Stephen H.

    2014-01-01

    The pathophysiological effects resulting from many bacterial diseases are caused by exotoxins released by the bacteria. Bacillus anthracis, a spore-forming bacterium, is such a pathogen, causing anthrax through a combination of bacterial infection and toxemia. B. anthracis causes natural infection in humans and animals and has been a top bioterrorism concern since the 2001 anthrax attacks in the USA. The exotoxins secreted by B. anthracis use CMG2 as the major toxin receptor and play essential roles in pathogenesis during the entire course of the disease. This review focuses on the activities of anthrax toxins and their roles in initial and late stages of anthrax infection. PMID:24684968

  12. A high-throughput, precipitating colorimetric sandwich ELISA microarray for shiga toxins

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Shiga toxins 1 and 2 (Stx1 and Stx2) from Shiga toxin-producing E. coli (STEC) bacteria were simultaneously detected with a newly developed, high-throughput antibody microarray platform. The proteinaceous toxins were immobilized and sandwiched between biorecognition elements (monoclonal antibodies)...

  13. Immunological evidence for a bacterial toxin aetiology in sudden infant death syndrome

    Microsoft Academic Search

    Steven Siarakas; Alissa Jane Brown; William G. Murrell

    1999-01-01

    Toxin-specific antibodies to clostridial, enterobacterial and staphylococcal toxins implicated in sudden infant death syndrome were studied in sera from sudden infant death syndrome infants and a comparison group of infants (babies with phenylketonuria). The results indicated a higher proportion of sera from sudden infant death syndrome infants contained IgA that bound to clostridial and enterobacterial toxins but a higher proportion

  14. Detection of pyrogenic toxins of Staphylococcus aureus in sudden infant death syndrome

    Microsoft Academic Search

    Abdulaziz Zorgani; Stephen D. Essery; Osama Al Madani; Alastair J. Bentley; Valerie S. James; Doris A. C. MacKenzie; Jean W. Keeling; Caroline Rambaud; John Hilton; C. Caroline Blackwell; Donald M. Weir; Anthony Busuttil

    1999-01-01

    It has been suggested that pyrogenic toxins of Staphylococcus aureus are involved in the series of events leading to some cases of sudden infant death syndrome (SIDS). The objectives of the study were to screen tissues from SIDS infants for pyrogenic toxins and to compare incidence of identification of these toxins among these infants from different countries. An enzyme-linked immunosorbent

  15. A Role for PACE4 in the Proteolytic Activation of Anthrax Toxin Protective Antigen

    Microsoft Academic Search

    VALERY M. GORDON; ALNAWAZ REHEMTULLA; STEPHEN H. LEPPLA

    1997-01-01

    Several bacterial protein toxins require activation by eukaryotic proteases. Previous studies have shown that anthrax toxin protective antigen (PA), Pseudomonas exotoxin A (PE), and diphtheria toxin (DT) are cleaved by furin C-terminal to the sequences RKKR, RQPR, and RVRR, respectively. Because furin-deficient cells retain some sensitivity to PA and DT, it is evident that other cellular proteases can activate these

  16. T3DB: a comprehensively annotated database of common toxins and their targets

    PubMed Central

    Lim, Emilia; Pon, Allison; Djoumbou, Yannick; Knox, Craig; Shrivastava, Savita; Guo, An Chi; Neveu, Vanessa; Wishart, David S.

    2010-01-01

    In an effort to capture meaningful biological, chemical and mechanistic information about clinically relevant, commonly encountered or important toxins, we have developed the Toxin and Toxin-Target Database (T3DB). The T3DB is a unique bioinformatics resource that compiles comprehensive information about common or ubiquitous toxins and their toxin-targets into a single electronic repository. The database currently contains over 2900 small molecule and peptide toxins, 1300 toxin-targets and more than 33 000 toxin-target associations. Each T3DB record (ToxCard) contains over 80 data fields providing detailed information on chemical properties and descriptors, toxicity values, protein and gene sequences (for both targets and toxins), molecular and cellular interaction data, toxicological data, mechanistic information and references. This information has been manually extracted and manually verified from numerous sources, including other electronic databases, government documents, textbooks and scientific journals. A key focus of the T3DB is on providing ‘depth’ over ‘breadth’ with detailed descriptions, mechanisms of action, and information on toxins and toxin-targets. T3DB is fully searchable and supports extensive text, sequence, chemical structure and relational query searches, similar to those found in the Human Metabolome Database (HMDB) and DrugBank. Potential applications of the T3DB include clinical metabolomics, toxin target prediction, toxicity prediction and toxicology education. The T3DB is available online at http://www.t3db.org. PMID:19897546

  17. 76 FR 72331 - Shiga Toxin-Producing Escherichia coli in Certain Raw Beef Products

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-23

    ...FSIS-2010-0023] Shiga Toxin-Producing Escherichia coli in Certain Raw Beef Products...non-O157 Shiga toxin-producing Escherichia coli in raw, intact and non-intact...non-O157 Shiga toxin-producing Escherichia coli in raw, intact and...

  18. Drug Insight: biological effects of botulinum toxin A in the lower urinary tract

    Microsoft Academic Search

    Clare J Fowler; Apostolos Apostolidis; William C de Groat; Christopher P Smith; George T Somogyi; K Roger Aoki; Michael B Chancellor

    2008-01-01

    Botulinum toxins can effectively and selectively disrupt and modulate neurotransmission in striated muscle. Recently, urologists have become interested in the use of these toxins in patients with detrusor overactivity and other urological disorders. In both striated and smooth muscle, botulinum toxin A (BTX-A) is internalized by presynaptic neurons after binding to an extracellular receptor (ganglioside and presumably synaptic vesicle protein

  19. Xylella fastidiosa plasmid-encoded PemK toxin is an endoribonuclease.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Stable inheritance of pXF-RIV11 in Xylella fastidiosa is conferred by the pemI/pemK plasmid addiction system. PemK serves as a toxin inhibiting bacterial growth; PemI is the corresponding antitoxin that blocks activity of PemK toxin by direct binding. PemK toxin and PemI antitoxin were over-expre...

  20. The coevolution of toxin and antitoxin genes drives the dynamics of bacterial addiction

    E-print Network

    Rankin, Daniel

    The coevolution of toxin and antitoxin genes drives the dynamics of bacterial addiction complexes Bacterial genomes commonly contain `addiction' gene complexes that code for both a toxin and a corre-segregational killing; genetic addiction; toxin­antitoxin systems 1. INTRODUCTION Genomes comprise multiple genes

  1. Computational Simulations of Interactions of Scorpion Toxins with the Voltage-Gated Potassium Ion Channel

    E-print Network

    Tian, Weidong

    Computational Simulations of Interactions of Scorpion Toxins with the Voltage-Gated Potassium Ion on a homology model of the Kv1.3 potassium channel, the recognitions of the six scorpion toxins, viz. agitoxin2, charybdotoxin, kaliotoxin, margatoxin, noxiustoxin, and Pandinus toxin, to the human Kv1.3 potassium channel

  2. Electrochemical and PM-IRRAS Characterization of Cholera Toxin Binding at a Model Biological Membrane

    E-print Network

    Dutcher, John

    Electrochemical and PM-IRRAS Characterization of Cholera Toxin Binding at a Model Biological-cholestrol bilayer, with cholera toxin B (CTB) units attached to the monosialote- trahexosylganglioside (GM1) binding potential. The data presented in this article show that binding cholera toxin to the membrane leads

  3. GM1 Clustering Inhibits Cholera Toxin Binding in Supported Phospholipid Membranes

    E-print Network

    GM1 Clustering Inhibits Cholera Toxin Binding in Supported Phospholipid Membranes Jinjun Shi ligand-receptor interactions between pentameric cholera toxin B subunits (CTB) and the corresponding-pathogen interactions3-5 are associated with multiva- lent ligand-receptor binding. The recognition of cholera toxin (CT

  4. Augmentation of Staphylococcal ?-Toxin Signaling by the Epidermal Platelet-Activating Factor Receptor

    Microsoft Academic Search

    Jeffrey B Travers; Donald Y M Leung; Christopher Johnson; Patrick Schlievert; Mariangela Marques; Jason Cosgrove; Keith L Clay

    2003-01-01

    Staphylococcal ?-toxin is a cytolytic toxin secreted by many strains of Staphylococcus aureus that has proinflammatory and cytotoxic effects on human keratinocytes. ?-toxin exerts its effects by forming a transmembrane pore that behaves like an ionophore for ions such as calcium. Because cellular membrane disruption with resultant intracellular calcium mobilization is a potent stimulus for the synthesis for the lipid

  5. Genetically modified anthrax lethal toxin safely delivers whole HIV protein antigens into the

    E-print Network

    Lieberman, Judy

    , 2000 (received for review January 24, 2000) Bacillus anthrax lethal toxin can be engineered to deliverGenetically modified anthrax lethal toxin safely delivers whole HIV protein antigens compartment of mammalian cells. The engineered anthrax toxin vaccine appears unlikely to induce an antibody

  6. Anthrax toxins: A weapon to systematically dismantle the host immune defenses

    Microsoft Academic Search

    Jean-Nicolas Tournier; Silvia Rossi Paccani; Anne Quesnel-Hellmann; Cosima T. Baldari

    2009-01-01

    Successful colonization of the host by bacterial pathogens relies on their capacity to evade the complex and powerful defenses opposed by the host immune system, at least in the initial phases of infection. The two toxins of Bacillus anthracis, lethal toxin and edema toxin, appear to have been shaped by evolution to assist the microorganism in this crucial function, in

  7. Development of a quail embryo model for the detection of botulinum toxin type A activity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Clostridium botulinum is a ubiquitous microorganism which under certain anaerobic conditions can produce botulinum toxins. Due to concerns in regards to both food-borne illness and the potential use of botulinum toxin as a biological weapon, the capability to assess the amount of toxin in a food or...

  8. Toxic and lethal effects of T-2 toxin upon intracerebral administration to rats

    Microsoft Academic Search

    Felix Bergmann; Boris Yagen; Dov Soffer

    1985-01-01

    T-2 toxin was given to rats in three ways: Subcutaneous or intracerebral injection of a solution in dimethyl sulfoxide (DMSO) and by implantation of toxin, adsorbed on talc, into various regions of diencephalon and brain stem. The latter method proved to be most effective. Within a few hours after administration of 10–20 µg toxin, the animals became restless, ataxic and

  9. Research with Red Tide Toxin Yields Potential Therapies for Cystic Fibrosis

    NSDL National Science Digital Library

    John Peterson

    This National Institutes of Health News article documents a study being done to use two compounds associated with Florida red tide to treat mucus build-up related to cystic fibrosis. Researchers began looking at the toxins associated with red tide to create "anti-toxins," which led them to question the anti-toxin's usefulness in fighting cystic fibrosis.

  10. Detection of toxins in single molecule level using deoxyribonucleic acid aptamers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Toxins in foodstuffs are always a threat to food safety Among many toxins related to food, ricin (category B toxin) from castor beans has been mentioned in some poisoning cases happened. Atomic Force Microscopy (AFM) is a widely used nanotechnology to detect biospecies in vitro and in situ. The AFM...

  11. Comparative gene expression of PSP-toxin producing and non-toxic Anabaena circinalis strains

    Microsoft Academic Search

    Francesco Pomati; Ralf Kellmann; Rosi Cavalieri; Brendan P. Burns; Brett A. Neilan

    2006-01-01

    Blooms of the freshwater cyanobacterium Anabaena circinalis are recognised as an important health risk worldwide due to the production of a range of toxins such as saxitoxin (STX) and its derivatives, also known as paralytic shellfish poisoning (PSP) toxins. In this study the transcriptional profile of PSP toxin-producing and non-toxic strains of A. circinalis was investigated by means of a

  12. Growth of Clostridium difficile and production of toxins A and B in complex and defined media

    Microsoft Academic Search

    S. C. Haslam; J. M. Ketley; T. J. Mitchell; J. Stephen; D. W. BURDONt; D. C. A. Candy

    1986-01-01

    Summary. The ability of several strains of Clostridium dif'icile to grow and to produce toxins A and B in complex and defined culture media has been studied with special reference to the amino-acid composition of the medium. The production of these toxins varied with the strain used and with the composition of the growth medium. Toxin A production was not

  13. Is association of labile enediyne chromophore a mutually assured protection for carrier protein?

    PubMed Central

    Kandaswamy, Jayachithra; Hariharan, Parameswaran; Kumar, Thallapuranam Krishnaswamy Suresh; Yu, Chin; Lu, Ta-Jung; Chin, Der-Hang

    2008-01-01

    Most conjugate proteins undergo both conformational and stability changes on ligand removal. When architecture remains unchanged in the protein holo and apo forms, it is uncertain whether the protein stability also remains unaltered in both of the forms. Neocarzinostatin (NCS), a chromoprotein possessing a potent enediyne chromophore stands for such an instance. Protein–chromophore interaction has not been thoroughly explored previously due to a lack of strategies to independently and simultaneously monitor changes in the NCS conjugates. Here we report a method by which one can detect the signal exclusively from only one of the NCS conjugates without the spectral interference from the other. Stability of the NCS protein is significantly correlated to the protein-bound chromophore, irrespective of denaturation by heat, pH, urea, or ethanol. Despite the similarity in protein backbone conformation, protein stability of the NCS holo form diminishes and equalizes to that of the apo form when the chromophore is released and degraded. Although the enediyne chromophore is highly unstable, it intriguingly protects the protein by which it is protected. Significant mutual reliance between the carrier protein and its naturally associated ligand unveils important information on the NCS drug stability. PMID:18601891

  14. Characterization of labile organic carbon in coastal wetland soils of the Mississippi River deltaic plain: relationships to carbon functionalities.

    PubMed

    Dodla, Syam K; Wang, Jim J; Delaune, Ronald D

    2012-10-01

    Adequate characterization of labile organic carbon (LOC) is essential to the understanding of C cycling in soil. There has been very little evaluation about the nature of LOC characterizations in coastal wetlands, where soils are constantly influenced by different redox fluctuations and salt water intrusions. In this study, we characterized and compared LOC fractions in coastal wetland soils of the Mississippi River deltaic plain using four different methods including 1) aerobically mineralizable C (AMC), 2) cold water extractable C (CWEC), 3) hot water extractable C (HWEC), and 4) salt extractable C (SEC), as well as acid hydrolysable C (AHC) which includes both labile and slowly degradable organic C. Molecular organic C functional groups of these wetland soils were characterized by (13)C solid-state nuclear magnetic resonance (NMR). The LOC and AHC increased with soil organic C (SOC) regardless of wetland soil type. The LOC estimates by four different methods were positively and significantly linearly related to each other (R(2)=0.62-0.84) and with AHC (R(2)=0.47-0.71). The various LOC fractions accounted for ?4.3% of SOC whereas AHC fraction represented 16-49% of SOC. AMC was influenced positively by O/N-alkyl and carboxyl C but negatively by alkyl C, whereas CWEC and SEC fractions were influenced only positively by carboxyl C but negatively by alkyl C in SOC. On the other hand, HWEC fraction was found to be only influenced positively by carbonyl C, and AHC positively by O/N-alkyl and alkyl C but negatively by aromatic C groups in SOC. Overall these relations suggested different contributions of various molecular organic C moieties to LOC in these wetlands from those often found for upland soils. The presence of more than 50% non-acid hydrolysable C suggested the dominance of relatively stable SOC pool that would be sequestered in these Mississippi River deltaic plain coastal wetland soils. The results have important implications to the understanding of the liability and refractory character of SOC in these wetlands as recent studies suggest marsh SOC to be an important C source in fueling hypoxia in the northern Gulf of Mexico. PMID:22850399

  15. Labile rhizosphere soil solution fraction for prediction of bioavailability of heavy metals and rare earth elements to plants.

    PubMed

    Shan, Xiao-Quan; Wang, Zhongwen; Wang, Weisheng; Zhang, Shuzhen; Wen, Bei

    2003-02-01

    A labile rhizosphere soil solution fraction has been recommended to predict the bioavailability of heavy metals and rare earth elements to plants. This method used moist rhizosphere soil in combination with a mixture of 0.01 mol L(-1) of low-molecular-weight organic acids (LMWOAs) as extractant. The extracted soil solutions were fractionated into two colloidal fractions of <0.45 microm (F(3)) and <0.2 microm (F(2)), and one truly dissolved fraction including free metal ions and inorganic and organic complexes (fractionlabile rhizosphere soil solution fraction, F(lrss). For the soil solutions extracted with a mixture of LMWOAs the concentrations of heavy metals and rare earth elements in F(2) and F(3) were quite similar. However, the mean concentrations of Cr, Ni, Zn, Cu, Pb, Cd, La, Ce, Pr, and Nd in F(lrss) accounted for 79.9%, 91.3%, 90.8%, 60.1%, 77.5%, 75.3%, 81.2%, 77.2%, 80.3%, and 79.5%, respectively, of their concentrations in F(2). In contrast, there were no differences in the extractable metal concentrations between the three fractions while the first step of the method recommended by the European Community of Reference (BCR), where 0.1 mol L(-1) acetic acid was used as an extractant. The single correlation analysis was made between metal concentrations in the different fractions of soil solutions and their concentrations in wheat. If the first step of BCR method was used there was no good correlation between heavy metals in soil pools and that in wheat shoots and roots. When LMWAOs were used a good correlation was obtained between the concentrations of heavy metals in soil pools and that in wheat roots, which followed a general order of r(1 kD, LMWOAs) >r(0.2 microm, LMWOAs) approximately r(0.45 microm, LMWOAs). In the case of rare earth elements the good correlation was obtained for both the wheat roots and shoots. Generally, the correlation coefficients obtained by LMWAOs were better than that obtained by the first step of BCR method. Therefore, LMWAOs and F(lrss) were strongly recommended to predict the bioavailability of metals in soil pools to plants. PMID:12589505

  16. Is litter decomposition 'primed' by primary producer-release of labile carbon in terrestrial and aquatic experimental systems?

    NASA Astrophysics Data System (ADS)

    Soares, A. Margarida P. M.; Kritzberg, Emma S.; Rousk, Johannes

    2015-04-01

    It is possible that recalcitrant organic matter (ROM) can be 'activated' by inputs of labile organic matter (LOM) through the priming effect (PE). Investigating the PE is of major importance to fully understand the microbial use of ROM and its role on carbon (C) and nutrient cycling in both aquatic and terrestrial ecosystems. In aquatic ecosystems it is thought that the PE is triggered by periphytic algae release of LOM. Analogously, in terrestrial systems it is hypothesized that the LOM released in plant rhizospheres, or from the green crusts on the surface of agricultural soils, stimulate the activity and growth of ROM decomposers. Most previous studies on PE have utilised pulse additions of single substrates at high concentrations. However, to achieve an assessment of the true importance of the PE, it is important to simulate a realistic delivery of LOM. We investigated, in a series of 2-week laboratory experiments, how primary producer (PP)-release of LOM influence litter degradation in terrestrial and aquatic experimental systems. We used soil (terrestrial) and pond water (aquatic) microbial communities to which litter was added under light and dark conditions. In addition, glucose was added at PP delivery rates in dark treatments to test if the putative PE in light systems could be reproduced. We observed an initial peak of bacterial growth rate followed by an overall decrease over time with no treatment differences. In light treatments, periphytic algae growth and increased fungal production was stimulated when bacterial growth declined. In contrast, both fungal growth and algal production were negligible in dark treatments. This reveals a direct positive influence of photosynthesis on fungal growth. To investigate if PP LOM supplements, and the associated fungal growth, translate into a modulated litter decomposition, we are using stable isotopes to track the use of litter and algal-derived carbon by determining the ?13C in produced CO2. Fungi and bacteria are the fundamental microbial decomposers and thus the main agents involved in respiration, ROM mobilisation and carbon cycling. By describing if and how litter decomposition is primed by primary producer-release of labile carbon we gain a better understanding of how microbial communities degrade OM in terrestrial and aquatic systems.

  17. Role of intracellular labile iron, ferritin, and antioxidant defence in resistance of chronically adapted Jurkat T cells to hydrogen peroxide

    PubMed Central

    Al-Qenaei, Abdullah; Yiakouvaki, Anthie; Reelfs, Olivier; Santambrogio, Paolo; Levi, Sonia; Hall, Nick D.; Tyrrell, Rex M.; Pourzand, Charareh

    2014-01-01

    To examine the role of intracellular labile iron pool (LIP), ferritin (Ft), and antioxidant defence in cellular resistance to oxidative stress on chronic adaptation, a new H2O2-resistant Jurkat T cell line “HJ16” was developed by gradual adaptation of parental “J16” cells to high concentrations of H2O2. Compared to J16 cells, HJ16 cells exhibited much higher resistance to H2O2-induced oxidative damage and necrotic cell death (up to 3 mM) and had enhanced antioxidant defence in the form of significantly higher intracellular glutathione and mitochondrial ferritin (FtMt) levels as well as higher glutathione-peroxidase (GPx) activity. In contrast, the level of the Ft H-subunit (FtH) in the H2O2-adapted cell line was found to be 7-fold lower than in the parental J16 cell line. While H2O2 concentrations higher than 0.1 mM fully depleted the glutathione content of J16 cells, in HJ16 cells the same treatments decreased the cellular glutathione content to only half of the original value. In HJ16 cells, H2O2 concentrations higher than 0.1 mM increased the level of FtMt up to 4-fold of their control values but had no effect on the FtMt levels in J16 cells. Furthermore, while the basal cytosolic level of LIP was similar in both cell lines, H2O2 treatment substantially increased the cytosolic LIP levels in J16 but not in HJ16 cells. H2O2 treatment also substantially decreased the FtH levels in J16 cells (up to 70% of the control value). In contrast in HJ16 cells, FtH levels were not affected by H2O2 treatment. These results indicate that chronic adaptation of J16 cells to high concentrations of H2O2 has provoked a series of novel and specific cellular adaptive responses that contribute to higher resistance of HJ16 cells to oxidative damage and cell death. These include increased cellular antioxidant defence in the form of higher glutathione and FtMt levels, higher GPx activity, and lower FtH levels. Further adaptive responses include the significantly reduced cellular response to oxidant-mediated glutathione depletion, FtH modulation, and labile iron release and a significant increase in FtMt levels following H2O2 treatment. PMID:24333634

  18. Isolated rat liver perfusion studies with cyclic heptapeptide toxins of Microcystis and Oscillatoria (freshwater cyanobacteria).

    PubMed

    Berg, K; Wyman, J; Carmichael, W; Dabholkar, A

    1988-01-01

    Isolated perfused rat livers were used to study the dose-dependent effects of three cyclic heptapeptide toxins isolated from Norwegian freshwater bloom samples containing Microcystis aeruginosa, Oscillatoria agardhii var. and Oscillatoria agardhii var. isothrix. The high pressure liquid chromatography (HPLC) purified toxins had an i.p. LD50 in the rat and mouse of approximately 50, 500 and 1000 micrograms/kg, respectively. Hepatic insult of the toxins at concentrations of 0.5-4.0 times the rat i.p. lethal dose were assessed by monitoring bile flow, accumulation of total protein in the perfusate, release of intracellular enzymes and histopathologic examination of perfused liver tissue. One hundred micrograms of Microcystis toxin produced cessation of bile flow during a 1 hr perfusion period, while the two Oscillatoria toxins required 1000 and 2000 micrograms of toxin, consistent with their lower LD50 values. Hepatic cell membranes remained intact during the perfusion since release of enzymes and proteins into the perfusate was similar for toxin treated and control livers, and histopathologic examination of Trypan Blue infused livers revealed exclusion of the dye from the intracellular compartment of the parenchyma. Histopathologic findings for all three toxins showed hepatocellular disassociation that increased with toxin concentration. At the ultrastructural level, all three toxins caused dose-dependent vesiculation of rough endoplasmic reticulum, formation of concentric whorls composed of rough-ER, mitochondrial swelling, large cytoplasmic vacuoles and altered bile canaliculi. These changes were similar to those found for previous in vivo studies using Microcystis cyclic heptapeptides from Scotland and Australia. The Oscillatoria toxins required five to ten times more toxin to produce similar effects as the Microcystis toxin. At the higher concentrations, the Oscillatoria toxins also caused a proliferation of smooth-ER. The isolated perfused rat liver was found to be a good model for studying the hepatocellular effects of different cyclic peptide toxins from cyanobacteria. PMID:3144062

  19. ???3-targeted Copper Nanoparticles Incorporating an Sn 2 Lipase-Labile Fumagillin Prodrug for Photoacoustic Neovascular Imaging and Treatment

    PubMed Central

    Zhang, Ruiying; Pan, Dipanjan; Cai, Xin; Yang, Xiaoxia; Senpan, Angana; Allen, John S.; Lanza, Gregory M.; Wang, Lihong V.

    2015-01-01

    Photoacoustic (PA) tomography enables multiscale, multicontrast and high-resolution imaging of biological structures. In particular, contrast-enhanced PA imaging offers high-sensitivity noninvasive imaging of neovessel sprout formation and nascent tubules, which are important biomarkers of malignant tumors and progressive atherosclerotic disease. While gold nanoparticles or nanorods have been used as PA contrast agents, we utilized high-density copper oleate small molecules encapsulated within a phospholipid surfactant (CuNPs) to generate a soft nanoparticle with PA contrast comparable to that from gold. Within the NIR window, the copper nanoparticles provided a 4-fold higher signal than that of blood. ???3-integrin targeting of CuNPs in a MatrigelTM angiogenesis mouse model demonstrated prominent (p<0.05) PA contrast enhancement of the neovasculature compared with mice given nontargeted or competitively inhibited CuNPs. Furthermore, incorporation of a Sn 2 lipase-labile fumagillin prodrug into the CuNP outer lipid membrane produced marked antiangiogenesis in the same model when targeted to the ???3-integrin, providing proof of concept in vivo for the first targeted PA - drug delivery agent. PMID:25553103

  20. Photoacoustic molecular imaging of angiogenesis using theranostic ???3-targeted copper nanoparticles incorporating a sn-2 lipase-labile fumagillin prodrug

    NASA Astrophysics Data System (ADS)

    Zhang, Ruiying; Cai, Xin; Yang, Xiaoxia; Senpan, Angana; Allen, John S.; Pan, Dipanjan; Lanza, Gregory M.; Wang, Lihong V.

    2014-03-01

    Photoacoustic (PA) tomography imaging is an emerging, versatile, and noninvasive imaging modality, which combines the advantages of both optical imaging and ultrasound imaging. It opens up opportunities for noninvasive imaging of angiogenesis, a feature of skin pathologies including cancers and psoriasis. In this study, high-density copper oleate encapsulated within a phospholipid surfactant (CuNPs) generated a soft nanoparticle with PA contrast comparable to gold. Within the near-infrared window, the copper nanoparticles can provide a signal more than 7 times higher that of blood. ???3-targeted of CuNPs in a Matrigel mouse model demonstrated prominent PA contrast enhancement of the neovasculature compared to mice given nontargeted or competitively inhibited CuNPs. Incorporation of a sn-2 lipase-labile fumagillin prodrug into the CuNPs produced marked antiangiogenesis in the same model, demonstrating the theranostic potential of a PA agent for the first time in vivo. With a PA signal comparable to gold-based nanoparticles yet a lower cost and demonstrated drug delivery potential, ???3-targeted CuNPs hold great promise for the management of skin pathologies with neovascular features.