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

Heat-labile enterotoxins as adjuvants or anti-inflammatory agents.

PubMed

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.

Nutritional Requirements for Synthesis of Heat-Labile Enterotoxin by Enterotoxigenic Strains of Escherichia coli

PubMed Central

Gilligan, Peter H.; Robertson, Donald C.

1979-01-01

Optimal growth conditions have been established for production of heat-labile enterotoxin (LT) by both porcine and human strains of enterotoxigenic (ENT+) Escherichia coli. There were no unusual growth factor requirements, and some strains produced fairly high levels of LT in a basal salts medium containing 0.5% glucose if the pH was carefully controlled. Several amino acids markedly stimulated LT synthesis when added to the basal salts-glucose medium. Methionine and lysine were the most stimulatory for both human and porcine strains. Either aspartic acid or glutamic acid further enhanced LT synthesis in the presence of methionine and lysine, with aspartic acid being more stimulatory for porcine strains and glutamic acid more stimulatory for human strains. There were no apparent vitamin requirements and no unusual cations needed for toxin synthesis except that Fe3+ was slightly stimulatory for porcine strains. The stimulation by Fe3+ was observed only in the presence of the three amino acids, suggesting that the effect was indirect rather than on toxin synthesis. The carbon source also influenced the yield of LT. Glucose supported maximal synthesis, but other carbon sources which exhibit a high degree of catabolite repression also supported high levels of synthesis. Little or no LT was released below pH 7.0; therefore, because the pH drops during growth from 7.5 to 6.8, even in highly buffered media, it was necessary to adjust the pH to 8.0 to effect complete release of cell-associated toxin. The defined medium containing three amino acids reduced the amount of UV-absorbing material in culture supernatants about fivefold and increased LT activity for various strains from two- to fivefold over a complex Casamino Acids-yeast extract medium. Conditions found to be optimal for synthesis of LT were inhibitory for the heat-stable enterotoxin. PMID:33900

Vaccination with plasmid DNA encoding a mutant toxic shock syndrome toxin-1 ameliorates toxin-induced lethal shock in mice.

PubMed

Feng, Mao-Hui; Cui, Jing-Chun; Nakane, Akio; Hu, Dong-Liang

2013-09-01

Staphylococcal toxic shock syndrome toxin-1 (TSST-1), a superantigenic toxin produced by Staphylococcus (S.) aureus, is a major cause of septic shock and toxic shock syndrome. To investigate whether vaccination with a plasmid DNA encoding a non-toxic mutant TSST-1 (mTSST-1) can protect mice against wild-type TSST-1-induced lethal shock, the mice were intranasally immunized with the plasmid DNA (named pcDNA-mTSST-1) plus a mucosal adjuvant, a non-toxic mutant labile toxin (mLT). After the immunization, the mice were challenged with TSST-1 and lipopolysaccharide (LPS). The survival rate of mice immunized with pcDNA-mTSST-1 plus mLT was higher than that of the control mice immunized with PBS alone, mLT alone, pcDNA-mTSST-1 alone, or a parent plasmid plus mLT. The titers of interferon-γ (IFN-γ) in the sera of mice immunized with pcDNA-mTSST-1 plus mLT were significantly lower than those of the mLT control mice. Immunization with pcDNA-mTSST-1 plus mLT increased the serum levels of TSST-1-specific antibodies, especially immunoglobulin G1 (IgG1) and IgG2a subclasses. Furthermore, the sera obtained from mice immunized with pcDNA-mTSST-1 plus mLT significantly inhibited the TSST-1-induced secretion of IFN-γ and tumor necrosis factor-α (TNF-α) in murine spleen cells in vitro. These results indicate that immunization with pcDNA-mTSST-1 plus mLT provides protection against the lethal toxic shock of mice induced by wild-type TSST-1. The protective effect could be due to TSST-1-specific neutralizing antibodies as well as the inhibition of IFN-γ and TNF-α secretions. Since TSST-1 is commonly released by invasive S. aureus, the pcDNA-mTSST-1 should be useful in preventing toxin-induced shock resulting from S. aureus infection.

Pilot study of whole-blood gamma interferon response to the Vibrio cholerae toxin B subunit and resistance to enterotoxigenic Escherichia coli-associated diarrhea.

PubMed

Flores, Jose; DuPont, Herbert L; Paredes-Paredes, Mercedes; Aguirre-Garcia, M Magdalena; Rojas, Araceli; Gonzalez, Alexei; Okhuysen, Pablo C

2010-05-01

Enterotoxigenic Escherichia coli (ETEC), which produces heat-labile toxin (LT), is a common cause of travelers' diarrhea (TD). The B subunit of ETEC LT is immunologically related to the B subunit of Vibrio cholerae toxin (CT). In this pilot study we evaluated the whole-blood gamma interferon response to CT B in 17 U.S. adults traveling to Mexico. Only one of nine subjects who demonstrated a cellular immune response as determined by whole-blood gamma interferon production to CT B on arrival to Mexico developed diarrhea, whereas five of eight without a cellular response developed diarrhea. Markers of the cellular immune response to ETEC LT could help in identifying individuals immune to ETEC LT, and these markers deserve additional study.

The Saccharomyces boulardii CNCM I-745 strain shows protective effects against the B. anthracis LT toxin.

PubMed

Pontier-Bres, Rodolphe; Rampal, Patrick; Peyron, Jean-François; Munro, Patrick; Lemichez, Emmanuel; Czerucka, Dorota

2015-10-30

The probiotic yeast Saccharomyces boulardii (S. boulardii) has been prescribed for the prophylaxis and treatment of several infectious diarrheal diseases. Gastrointestinal anthrax causes fatal systemic disease. In the present study, we investigated the protective effects conferred by Saccharomyces boulardii CNCM I-745 strain on polarized T84 columnar epithelial cells intoxicated by the lethal toxin (LT) of Bacillus anthracis. Exposure of polarized T84 cells to LT affected cell monolayer integrity, modified the morphology of tight junctions and induced the formation of actin stress fibers. Overnight treatment of cells with S. boulardii before incubation with LT maintained the integrity of the monolayers, prevented morphological modification of tight junctions, restricted the effects of LT on actin remodeling and delayed LT-induced MEK-2 cleavage. Mechanistically, we demonstrated that in the presence of S. boulardii, the medium is depleted of both LF and PA sub-units of LT and the appearance of a cleaved form of PA. Our study highlights the potential of the S. boulardii CNCM I-745 strain as a prophylactic agent against the gastrointestinal form of anthrax.

The Saccharomyces boulardii CNCM I-745 Strain Shows Protective Effects against the B. anthracis LT Toxin

PubMed Central

Pontier-Bres, Rodolphe; Rampal, Patrick; Peyron, Jean-François; Munro, Patrick; Lemichez, Emmanuel; Czerucka, Dorota

2015-01-01

The probiotic yeast Saccharomyces boulardii (S. boulardii) has been prescribed for the prophylaxis and treatment of several infectious diarrheal diseases. Gastrointestinal anthrax causes fatal systemic disease. In the present study, we investigated the protective effects conferred by Saccharomyces boulardii CNCM I-745 strain on polarized T84 columnar epithelial cells intoxicated by the lethal toxin (LT) of Bacillus anthracis. Exposure of polarized T84 cells to LT affected cell monolayer integrity, modified the morphology of tight junctions and induced the formation of actin stress fibers. Overnight treatment of cells with S. boulardii before incubation with LT maintained the integrity of the monolayers, prevented morphological modification of tight junctions, restricted the effects of LT on actin remodeling and delayed LT-induced MEK-2 cleavage. Mechanistically, we demonstrated that in the presence of S. boulardii, the medium is depleted of both LF and PA sub-units of LT and the appearance of a cleaved form of PA. Our study highlights the potential of the S. boulardii CNCM I-745 strain as a prophylactic agent against the gastrointestinal form of anthrax. PMID:26529015

Structure–activity correlations of variant forms of the B pentamer of Escherichia coli type II heat-labile enterotoxin LT-IIb with Toll-like receptor 2 binding

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cody, Vivian, E-mail: cody@hwi.buffalo.edu; University at Buffalo, 700 Ellicott Street, Buffalo, NY 14203; Pace, Jim

2012-12-01

Structural data for the S74D variant of the pentameric B subunit of type II heat-labile enterotoxin of Escherichia coli reveal a smaller pore opening that may explain its reduced Toll-like receptor binding affinity compared to that of the wild type enterotoxin. The explanation for the enhanced Toll-like receptor binding affinity of the S74A variant is more complex than simply being attributed to the pore opening. The pentameric B subunit of the type II heat-labile enterotoxin of Escherichia coli (LT-IIb-B{sub 5}) is a potent signaling molecule capable of modulating innate immune responses. It has previously been shown that LT-IIb-B{sub 5}, butmore » not the LT-IIb-B{sub 5} Ser74Asp variant [LT-IIb-B{sub 5}(S74D)], activates Toll-like receptor (TLR2) signaling in macrophages. Consistent with this, the LT-IIb-B{sub 5}(S74D) variant failed to bind TLR2, in contrast to LT-IIb-B{sub 5} and the LT-IIb-B{sub 5} Thr13Ile [LT-IIb-B{sub 5}(T13I)] and LT-IIb-B{sub 5} Ser74Ala [LT-IIb-B{sub 5}(S74A)] variants, which displayed the highest binding activity to TLR2. Crystal structures of the Ser74Asp, Ser74Ala and Thr13Ile variants of LT-IIb-B{sub 5} have been determined to 1.90, 1.40 and 1.90 Å resolution, respectively. The structural data for the Ser74Asp variant reveal that the carboxylate side chain points into the pore, thereby reducing the pore size compared with that of the wild-type or the Ser74Ala variant B pentamer. On the basis of these crystallographic data, the reduced TLR2-binding affinity of the LT-IIb-B{sub 5}(S74D) variant may be the result of the pore of the pentamer being closed. On the other hand, the explanation for the enhanced TLR2-binding activity of the LT-IIb-B{sub 5}(S74A) variant is more complex as its activity is greater than that of the wild-type B pentamer, which also has an open pore as the Ser74 side chain points away from the pore opening. Data for the LT-IIb-B{sub 5}(T13I) variant show that four of the five variant side chains point to the

Immunological Relationship of Different Preparations of Coliform Enterotoxins

PubMed Central

Klipstein, Frederick A.; Engert, Richard F.

1978-01-01

Antisera raised in rabbits to ultrafiltrate toxin preparations containing either the heat-labile (LT) toxin form obtained from whole cell lysates or broth filtrates or the heat-stable (ST) toxin form prepared from broth filtrates from nontoxigenic and toxigenic strains of Escherichia coli and Klebsiella were examined for their ability to neutralize the secretory effect on water transport of these toxins in the rat jejunum as determined by the in vivo marker perfusion technique. Antisera to the heat-labile toxin derived from whole cell lysate preparations from nontoxigenic strains had no neutralizing effect. Antisera to both types of LT preparation from both toxigenic strains neutralized, with several exceptions, all of the homologous and heterologous LT toxins as well as a heat-labile toxin preparation derived from sequential ultrafiltration of cell-free whole cell lysates which had a defined molecular weight of between 30,000 and 100,000. These antisera also neutralized homologous and heterologous ST preparations obtained from broth filtrates, but they had no neutraliziṅg effect on low-molecular-weight, ST toxin material obtained during the sequential ultrafiltration of cell lysates. Antisera to ST prepared from broth filtrates had no neutralizing capacity against either LT or ST toxin preparations. These observations (i) indicate that the immunological relationship of E. coli and Klebsiella LT and ST toxins extends to antisera raised against LT prepared by several different methods, (ii) raise the possibility that, based on the response to antisera to LT, there may be several immunologically heterogeneous forms of low-molecular-weight ST toxin, and (c) confirm the lack of immunogenicity of ST. PMID:361578

Immunization with Salmonella Enteritidis secreting mucosal adjuvant labile toxin confers protection against wild type challenge via augmentation of CD3+CD4+ T-cell proliferation and enhancement of IFN-γ, IL-6 and IL-10 expressions in chicken.

PubMed

Lalsiamthara, Jonathan; Lee, John Hwa

2017-02-01

The protective efficacy and immunological profiles of chickens immunized with an attenuated Salmonella Enteritidis (SE) constitutively secreting double mutant heat labile enterotoxin (dmLT) were investigated. The dmLT is a detoxified variant of Escherichia coli heat labile toxin and is a potent mucosal adjuvant capable of inducing both humoral and cell-mediated immunity. In this study, four-week-old chickens were inoculated with SE-dmLT strain JOL1641, parental SE strain JOL1087 or phosphate buffered saline control. Peripheral blood mononuclear cells of SE-dmLT inoculated birds showed significant proliferation upon stimulation with SE antigens as compared to the control and JOL1087 groups (P⩽0.05). One week post-challenge, the ratio of CD3 + CD4 + to CD3 + CD8 + T-cells showed a significant increase in the immunized groups. Significant increases in IFN-γ levels were observed in JOL1641 birds immunized via oral and intramuscular routes. While immunizations with the JOL1087 strain via the intramuscular route also induced significant increases in IFN-γ, immunization via the oral route did not trigger significant changes. Pro-inflammatory cytokine IL-6 was also elevated significantly in immunized birds; a significant elevation of IL-10 was observed only in oral immunization with JOL1641 (P⩽0.05). JOL1641 immunized birds showed significant reduction of challenge bacterial-organ recovery as compared to JOL1087 and non-immunized birds. Collectively, our results revealed that immunization with the adjuvant-secreting S. Enteritidis confers protection against wild type SE challenge via induction of strong cell proliferative response, augmentation of CD3 + CD4 + : CD3 + CD8 + T-cells ratio and enhancement of IFN-γ, IL-6 and IL-10 cytokine secretion. Copyright © 2016 Elsevier Ltd. All rights reserved.

Toward the development of a stable, freeze-dried formulation of Helicobacter pylori killed whole cell vaccine adjuvanted with a novel mutant of E. coli heat-labile toxin

PubMed Central

Summerton, Nancy A.; Welch, Richard W.; Bondoc, Laureano; Yang, Huei-Hsiung; Pleune, Brett; Ramachandran, Naryaswamy; Harris, Andrea M.; Bland, Desiree; Jackson, W. James; Park, Sukjoon; Clements, John D.; Nabors, Gary S.

2009-01-01

No vaccine exists for the prevention of infection with the ubiquitous gastric pathogen Helicobacter pylori, and drug therapy for the infection is complicated by poor patient compliance, the high cost of treatment, and ineffectiveness against drug resistant strains. A new medical advancement is required to reduce the incidence of peptic ulcer disease and stomach cancer, two conditions caused by infection with H. pylori. Clinical trials have been performed with a formalin-inactivated Helicobacter pylori Whole Cell (HWC) vaccine, given orally in combination with the mucosal adjuvant mLT(R192G), a mutant of E. coli heat-labile toxin. Following the initial dose of this vaccine, some subjects experienced gastrointestinal side effects. To reduce side effects and potentially further increase the amount of adjuvant that can safely be administered with the HWC vaccine, experiments were performed with a form of LT that carried two mutations in the A subunit, a substitution of G for R at position 192, and A for L at position 211. The double-mutant LT (dmLT) adjuvant stimulated immune responses as effectively as the single mutant LT in mice. Additionally, following a challenge infection, the dmLT-adjuvanted vaccine was as effective as single mutant LT in reducing gastric urease levels (diagnostic for H. pylori infection), and H. pylori colonization in the stomach as assessed by quantitative analysis of stomach homogenates. A lyophilized formulation of HWC was developed to improve stability and to potentially reduce reliance on cold chain maintenance. It was observed that a dmLT-adjuvanted lyophilized vaccine was equally as protective in the mouse model as the liquid formulation as assessed by gastric urease analysis and analysis of stomach homogenates for viable H. pylori. No readily detectable effect of tonicity or moisture content was observed for the lyophilized vaccine within the formulation limits evaluated. In an accelerated stability study performed at 37°C the

Discovery of the cell-penetrating function of A2 domain derived from LTA subunit of Escherichia coli heat-labile enterotoxin.

PubMed

Liu, Di; Guo, Hua; Zheng, Wenyun; Zhang, Na; Wang, Tianwen; Wang, Ping; Ma, Xingyuan

2016-06-01

Heat-labile enterotoxin (LT) is a protein toxin produced by enterotoxigenic Escherichia coli (ETEC). As a bacterial toxin, LT holotoxin can enter intestinal epithelial cells and cause diarrhea. In addition, LT is also a powerful mucosal adjuvant capable of enhancing the strong immune responses to co-administered antigens. However, the LT immunological mechanism is still not clear in some aspects, especially with the respect to how the LTA subunit functions alone. Here, we discovered that the A2 domain of LTA could carry a fluorescent protein into cells, whose function is similar to a cell-penetrating peptide. The transmembrane-transporting ability of the A2 domain is non-specific in its cell-penetrating function, which was shown through testing with different cell types. Moreover, the LTA2 fusion protein penetrated a fluorescently labeled cell membrane that identified LTA2 internalization through membrane transport pathways, and showed it finally localized in the endoplasmic reticulum. Furthermore, low-temperature stress and pharmacological agent treatments showed that the LTA2 internalization route is a temperature-dependent process involving the clathrin-mediated endocytosis and the macropinocytosis pathways. These results could explain the internalization of the LTA subunit alone without the LTB pentamer, contributing to a better understanding of LTA working as a mucosal adjuvant; they also suggest that the A2 domain could be used as a novel transport vehicle for research and treatment of disease.

Development and preclinical evaluation of safety and immunogenicity of an oral ETEC vaccine containing inactivated E. coli bacteria overexpressing colonization factors CFA/I, CS3, CS5 and CS6 combined with a hybrid LT/CT B subunit antigen, administered alone and together with dmLT adjuvant.

PubMed

Holmgren, J; Bourgeois, L; Carlin, N; Clements, J; Gustafsson, B; Lundgren, A; Nygren, E; Tobias, J; Walker, R; Svennerholm, A-M

2013-05-07

A first-generation oral inactivated whole-cell enterotoxigenic Escherichia coli (ETEC) vaccine, comprising formalin-killed ETEC bacteria expressing different colonization factor (CF) antigens combined with cholera toxin B subunit (CTB), when tested in phase III studies did not significantly reduce overall (generally mild) ETEC diarrhea in travelers or children although it reduced more severe ETEC diarrhea in travelers by almost 80%. We have now developed a novel more immunogenic ETEC vaccine based on recombinant non-toxigenic E. coli strains engineered to express increased amounts of CF antigens, including CS6 as well as an ETEC-based B subunit protein (LCTBA), and the optional combination with a nontoxic double-mutant heat-labile toxin (LT) molecule (dmLT) as an adjuvant. Two test vaccines were prepared under GMP: (1) A prototype E. coli CFA/I-only formalin-killed whole-cell+LCTBA vaccine, and (2) A "complete" inactivated multivalent ETEC-CF (CFA/I, CS3, CS5 and CS6 antigens) whole-cell+LCTBA vaccine. These vaccines, when given intragastrically alone or together with dmLT in mice, were well tolerated and induced strong intestinal-mucosal IgA antibody responses as well as serum IgG and IgA responses to each of the vaccine CF antigens as well as to LT B subunit (LTB). Both mucosal and serum responses were further enhanced (adjuvanted) when the vaccines were co-administered with dmLT. We conclude that the new multivalent oral ETEC vaccine, both alone and especially in combination with the dmLT adjuvant, shows great promise for further testing in humans. Copyright © 2013 Elsevier Ltd. All rights reserved.

Modulation of the humoral and cellular immune response in Abeta immunotherapy by the adjuvants monophosphoryl lipid A (MPL), cholera toxin B subunit (CTB) and E. coli enterotoxin LT(R192G).

PubMed

Maier, Marcel; Seabrook, Timothy J; Lemere, Cynthia A

2005-10-25

Abeta vaccination or passive transfer of human-specific anti-Abeta antibodies are approaches under investigation to prevent and/or treat Alzheimer's disease (AD). Successful active Abeta vaccination requires a strong and safe adjuvant to induce anti-Abeta antibody formation. We compared the adjuvants monophosphoryl lipid A (MPL)/trehalose dicorynomycolate (TDM), cholera toxin B subunit (CTB) and Escherichia coli heat-labile enterotoxin LT(R192G) for their ability to induce a humoral and cellular immune reaction, using fibrillar Abeta1-40/42 as a common immunogen in wildtype B6D2F1 mice. Subcutaneous (s.c.) administration with MPL/TDM resulted in anti-Abeta antibodies levels up to four times higher compared to s.c. LT(R192G). Using MPL/TDM, the anti-Abeta antibodies induced were mainly IgG2b, IgG1 and lower levels of IgG2a and IgM, with a moderate splenocyte proliferation and IFN-gamma production in vitro upon stimulation with Abeta1-40/42. LT(R192G), previously shown by us to induce robust titers of anti-Abeta antibodies, generated predominantly IgG2b and IgG1 anti-Abeta antibodies with very low splenocyte proliferation and IFN-gamma production. Weekly intranasal (i.n.) administration over 11 weeks of Abeta40/42 with CTB induced only moderate levels of antibodies. All immunogens generated antibodies that recognized mainly the Abeta1-7 epitope and specifically detected amyloid plaques on AD brain sections. In conclusion, MPL/TDM, in addition to LT(R192G), is an effective adjuvant when combined with Abeta40/42 and may aid in the design of Abeta immunotherapy.

Clinical and biochemical significance of toxin production by Aeromonas hydrophila.

PubMed Central

Kindschuh, M; Pickering, L K; Cleary, T G; Ruiz-Palacios, G

1987-01-01

Production of cytotoxin and enterotoxin by Aeromonas strains obtained from stools of 50 children in Mexico and Texas and from blood of 9 children with sepsis was determined. Results were correlated with clinical features of infected children as well as with biochemical traits of Aeromonas strains. Cytotoxin was produced by 40 of 42 Aeromonas strains (95%) isolated from stools of children with diarrhea, by all 8 isolates from stools of well children, and by all 9 isolates from children with sepsis. There was no difference in the quantities (amount of cytotoxin per milligram of protein required to kill 50% of the cells) of cytotoxin produced and in clinical manifestations among the groups. None of the isolates produced a toxin that could be neutralized by antiserum raised against Shiga toxin produced by Shigella dysenteriae 1 60R. Heat-labile-like enterotoxin (LT) was produced by 26 of 42 stool isolates (62%), while only 1 of the 42 isolates (2%) produced enterotoxinlike activity in suckling mice; 65% of the cytotoxin-producing strains also produced an LT-like material. All strains from blood produced LT-like material, and 2 of 6 (33%) produced activity in suckling mice. All strains produced hemolysin; 37 of 57 (65%) were Voges-Proskauer positive; 27 of 57 (47%) were lysine decarboxylase positive by API 20E strips, none were positive for lysine decarboxylose production by lysin-iron agar slants at 24 h, but 17 of 54 (31%) were positive at 48 h. There was no correlation between biochemical reactions and enterotoxin or cytotoxin production. There appears to be no correlation between toxin production by Aeromonas spp. and gastroenteritis. PMID:3584426

Protective Effect of Active Immunization with Purified Escherichia coli Heat-Labile Enterotoxin in Rats

PubMed Central

Klipstein, Frederick A.; Engert, Richard F.

1979-01-01

The protective effect of active immunization by different routes with a purified preparation of the polymyxin-release form of Escherichia coli heat-labile toxin was evaluated in rats. Immunized animals were challenged by placing toxin into ligated ileal loops at dosages which produced either 50% or the maximum secretory response in unimmunized rats. Immunization exclusively by the parenteral route yielded significant protection. Rats were also protected when parenteral priming was followed by boosting given either directly into the duodenum or perorally 2 h after intragastric cimetidine, but not when the peroral boosts were given with bicarbonate. Immunization administered entirely by the peroral route with cimetidine yielded protection but only when the immunizing dosage was fivefold greater than that found effective in the parenteral-peroral approach. Rats immunized exclusively by the parenteral route and those boosted perorally with cimetidine were also tested, and found to be protected, against challenge with viable organisms of strains that produce either heat-labile toxin alone or both heat-labile and heat-stable toxin, but they were not protected against a strain which produces just heat-stable toxin. Geometric mean serum antibody titers were increased by 16-fold or more over control values in those groups of rats in which protection was achieved, with the exception of those immunized exclusively by the peroral route. These observations demonstrate that (i) active immunization with purified E. coli heat-labile toxin results in significant protection against both this toxin as well as viable organisms which produce it, but not against viable strains which produce heat-stable toxin only, and (ii) concomitant ablation of gastric secretion by the use of cimetidine renders the peroral route of immunization effective. They suggest that prophylactic immunization against diarrheal disease caused by heat-labile toxin-producing strains of E. coli may be feasible in

Toll-Like Receptor 2 Mediates Cellular Activation by the B Subunits of Type II Heat-Labile Enterotoxins

PubMed Central

Hajishengallis, George; Tapping, Richard I.; Martin, Michael H.; Nawar, Hesham; Lyle, Elizabeth A.; Russell, Michael W.; Connell, Terry D.

2005-01-01

The type II heat-labile enterotoxins (LT-IIa and LT-IIb) of Escherichia coli have an AB5 subunit structure similar to that of cholera toxin (CT) and other type I enterotoxins, despite significant differences in the amino acid sequences of their B subunits and different ganglioside receptor specificities. LT-II holotoxins and their nontoxic B subunits display unique properties as immunological adjuvants distinct from those of CT and its B subunits. In contrast to type II holotoxins, the corresponding pentameric B subunits, LT-IIaB and LT-IIbB, stimulated cytokine release in both human and mouse cells dependent upon Toll-like receptor 2 (TLR2). Induction of interleukin-1β (IL-1β), IL-6, IL-8, or tumor necrosis factor alpha in human THP-1 cells by LT-IIaB or LT-IIbB was inhibited by anti-TLR2 but not by anti-TLR4 antibody. Furthermore, transient expression of TLR1 and TLR2 in human embryonic kidney 293 cells resulted in activation of a nuclear factor-κB-dependent luciferase gene in response to LT-IIaB or LT-IIbB. Moreover, peritoneal macrophages from TLR2-deficient mice failed to respond to LT-IIaB or LT-IIbB, in contrast to wild-type or TLR4-deficient cells. These results demonstrate that besides their established binding to gangliosides, the B subunits of type II enterotoxins also interact with TLR2. Although a ganglioside-nonbinding mutant (T34I) of LT-IIaB effectively induced cytokine release, a phenotypically similar point mutation (T13I) in LT-IIbB abrogated cytokine induction, suggesting a variable requirement for gangliosides as coreceptors in TLR2 agonist activity. TLR2-dependent activation of mononuclear cells by type II enterotoxin B subunits appears to be a novel mechanism whereby these molecules may exert their immunomodulatory and adjuvant activities. PMID:15731031

Efficacy and safety of a patch vaccine containing heat-labile toxin from Escherichia coli against travellers' diarrhoea: a phase 3, randomised, double-blind, placebo-controlled field trial in travellers from Europe to Mexico and Guatemala.

PubMed

Behrens, Ronald H; Cramer, Jakob P; Jelinek, Tomas; Shaw, Hilary; von Sonnenburg, Frank; Wilbraham, Darren; Weinke, Thomas; Bell, David J; Asturias, Edwin; Pauwells, Hermann L Enkerlin; Maxwell, Roberto; Paredes-Paredes, Mercedes; Glenn, Gregory M; Dewasthaly, Shailesh; Stablein, Donald M; Jiang, Zhi-Dong; DuPont, Herbert L

2014-03-01

Enterotoxigenic Escherichia coli (ETEC) is a major cause of travellers' diarrhoea. We investigated the efficacy and safety of a skin-patch vaccine containing the pathogen's heat-labile toxin (LT) in a population of travellers to Mexico and Guatemala. In this phase 3, randomised, double-blind, placebo-controlled field trial, healthy adults (aged 18-64 years) travelling from Germany or the UK to Mexico or Guatemala were assigned in a 1:1 ratio by a dynamic electronic randomisation system to receive transcutaneous immunisation with a patch containing 37.5 μg of ETEC LT or a placebo patch. Participants, site staff, and the investigators who did the analyses were masked to group assignment. Participants were vaccinated before travel, with two patches given 14 days apart. In the destination country, participants tracked stool output in a diary and provided stool samples for pathogen identification if diarrhoea occurred. The primary endpoint was the proportion of participants with at least one episode of moderate-to-severe diarrhoea (defined as four or more unformed stools in a 24 h period) in which either or both ETEC enterotoxins (LT and heat-stable toxin [ST]) were detected. The study is registered at ClinicalTrials.gov, number NCT00993681. 2036 participants were recruited and randomly assigned between Oct 14, 2009, and Aug 13, 2010, with 1016 allocated to receive the LT patch and 1020 the placebo patch. 821 participants in the LT-patch group and 823 in the placebo group received both vaccinations and were analysed in the per-protocol population. 30 (3.7%, 95% CI 2.5-5.2) participants in the LT-patch group and 46 (5.6%, 4.1-7.4) in the placebo group had moderate or severe ETEC diarrhoea (vaccine efficacy 34.6%, -2.2 to 58.9; p=0.0621). 9333 local (ie, patch-site) adverse events (including erythema, rash, pruritus, hyperpigmentation, pain, hypopigmentation, and oedema) occurred in 943 (93%) of 1015 participants in the LT-patch group, compared with 1444 local adverse

Transcutaneous immunization with tetanus toxoid and mutants of Escherichia coli heat-labile enterotoxin as adjuvants elicits strong protective antibody responses.

PubMed

Tierney, Rob; Beignon, Anne-Sophie; Rappuoli, Rino; Muller, Sylviane; Sesardic, Dorothea; Partidos, Charalambos D

2003-09-01

In this study, the adjuvanticity of 2 nontoxic derivatives (LTK63 and LTR72) of heat-labile enterotoxin of Escherichia coli (LT) was evaluated and was compared with that of a cytosine phosphodiester-guanine (CpG) motif, after transcutaneous immunization with tetanus toxoid (TT). TT plus LTR72 elicited the strongest antibody responses, compared with those elicited by the other vaccines (TT, TT plus LTK63, TT plus CpG, and TT plus LTK63 plus CpG); it neutralized the toxin and conferred full protection after passive transfer in mice. Preexisting immunity to LT mutants did not adversely affect their adjuvant potency. Both LTK63 and LTR72 promoted the induction of IgG1 antibodies. In contrast, mice receiving either CpG motif alone or CpG motif plus LTK63 produced strong IgG2a anti-TT antibody responses. Overall, these findings demonstrate that mutants of enterotoxins with reduced toxicity are effective adjuvants for transcutaneous immunization.

Influence of Route of Administration on Immediate and Extended Protection in Rats Immunized with Escherichia coli Heat-Labile Enterotoxin

PubMed Central

Klipstein, Frederick A.; Engert, Richard F.

1980-01-01

The effect of route of administration, dosage, and number of boosts employed during immunization with the polymyxin-release form of Escherichia coli heat-labile (LT) enterotoxin on the degree and duration of protection afforded was evaluated in rats which were challenged by the ligated loop technique. Increasing the boosting dosage by fivefold from 50 to 250 μg resulted in a marked increase in protection against challenge with toxin in rats immunized either just by the parenteral route (i.p./i.p.) or by a parenteral prime, followed by peroral boosts (i.p./p.o.) in rats pretreated with cimetidine to ablate gastric secretions; such was not the case, however, even with a 50-fold increase in dosage in rats immunized just by the peroral route (p.o./p.o.). Four weekly peroral boosts were required to achieve the strongest degree of protection. Increasing the boosting dosage also increased the degree of protection against challenge with viable LT+/ST− and LT+/ST+ strains (ST indicates heat-stable enterotoxin) in rats immunized by the i.p./p.o., but not by the i.p./i.p., route; no protection was evident against an LT−/ST+ strain. Protection was lost within 3 weeks after immunization in rats immunized by the i.p./i.p. route. In contrast, protection was extended over the 3-month observation period in those immunized by the i.p./p.o. route; the degree of protection was enhanced in rats which received an additional boost at 2 months. These observations establish the fact that immunization with LT is similar to that with cholera toxin in that arousal of the local immune intestinal response by means of peroral immunization provides maximal extended protection. PMID:6987180

Differential interaction of Escherichia coli heat-labile toxin and cholera toxin with pig intestinal brush border glycoproteins depending on their ABH and related blood group antigenic determinants.

PubMed

Balanzino, L E; Barra, J L; Monferran, C G; Cumar, F A

1994-04-01

The ability of glycoproteins from pig intestinal brush border membranes (BBM) to bind cholera toxin (CT) or heat-labile toxins from strains of Escherichia coli isolated from human (LTh) or pig (LTp) intestines was studied. Glycoproteins capable of binding the toxins are also recognized by antibodies or lectins specific for ABO(H) blood group and related antigens. Pigs expressing A, H, or I antigenic determinants were used for comparison. The toxin-binding capacity of a glycoprotein depends on the toxin type and the blood group epitope borne by the glycoprotein. LTh and LTp preferably bound to several blood group A-active glycoproteins rather than H-active glycoproteins. By contrast, CT practically did not recognize either blood group A- or blood group H-active glycoproteins, while glycoproteins from pigs expressing I antigenic determinants were able to interact with LTh, LTp, and CT. LTh, LTp, or CT glycoprotein binding was selectively inhibited by specific lectins or monosaccharides. Affinity purification of the toxin binding brush border glycoproteins on the basis of their blood group reactivity suggests that such glycoproteins are hydrolytic enzymes. BBM from A+ pigs contain about 27 times more LTh binding sites, in addition to those recognized by CT, than an equivalent membrane preparation from H+ pigs. The present findings may help clarify some previous unclear results on LTh binding to intestinal BBM glycoproteins obtained by use of animals not typed by their ABO(H) blood group phenotype.

Expression and immunogenicity of enterotoxigenic Escherichia coli heat-labile toxin B subunit in transgenic rice callus.

PubMed

Kim, Tae-Geum; Kim, Bang-Geul; Kim, Mi-Young; Choi, Jae-Kwon; Jung, Eun-Sun; Yang, Moon-Sik

2010-01-01

Enterotoxigenic Escherichia coli is one of the leading causes of diarrhea in developing countries, and the disease may be fatal in the absence of treatment. Enterotoxigenic E. coli heat-labile toxin B subunit (LTB) can be used as an adjuvant, as a carrier of fused antigens, or as an antigen itself. The synthetic LTB (sLTB) gene, optimized for plant codon usage, has been introduced into rice cells by particle bombardment-mediated transformation. The integration and expression of the sLTB gene were observed via genomic DNA PCR and western blot analysis, respectively. The binding activity of LTB protein expressed in transgenic rice callus to G(M1)-ganglioside, a receptor for biologically active LTB, was confirmed by G(M1)-ELISA. Oral inoculation of mice with lyophilized transgenic rice calli containing LTB generated significant IgG antibody titers against bacterial LTB, and the sera of immunized mice inhibited the binding of bacterial LTB to G(M1)-ganglioside. Mice orally immunized with non-transgenic rice calli failed to generate detectable anti-LTB IgG antibody titers. Mice immunized with plant-produced LTB generated higher IgG1 antibody titers than IgG2a, indicating a Th2-type immune response. Mice orally immunized with lyophilized transgenic rice calli containing LTB elicited higher fecal IgA antibody titers than mice immunized with non-transgenic rice calli. These experimental results demonstrate that LTB proteins produced in transgenic rice callus and given to mice by oral administration induce humoral and secreted antibody immune responses. We suggest that transgenic rice callus may be suitable as a plant-based edible vaccine to provide effective protection against enterotoxigenic E. coli heat-labile toxin.

Protective Effect of Immunization of Rats with Holotoxin or B Subunit of Escherichia coli Heat-Labile Enterotoxin

PubMed Central

Klipstein, Frederick A.; Engert, Richard F.

1981-01-01

The relative immunogenicities of three forms of the Escherichia coli heatlabile enterotoxin (LT), the holotoxin, its B subunit, and the polymyxin-release form (PM LT) were compared by immunizing rats with various dosages of each given exclusively by the parenteral (IP/IP) or peroral (PO/PO) routes or by a combination of the two (IP/PO). The degree of protection was evaluated by challenge in ligated ileal loops, and the serum antitoxin response was determined by an enzyme-linked immunosorbent assay with homologous antigens. When given by the PO/PO route, each LT antigen provided only weak protection against the toxin and virtually none against viable LT-producing strains; serum antitoxin titers were not significantly increased. When the toxins were given after a parental primary immunization by either the IP/IP or the IP/PO routes, each LT antigen provided a dose-related increase in serum antitoxin titers and in the degree of protection against the toxin as well as against viable strains which produce LT alone (LT+/ST−) or in combination with the heat-stable toxin (LT+/ST+). The degree of protection against viable bacteria, particularly the LT+/ST+ strain, was stronger in animals which received booster immunizations by the PO route. When expressed on the basis of molar equivalents, holotoxin provided significant protection (a protection index of >5 against toxin challenge and >50% reduced secretion with bacterial challenge) with 4 to 15 times fewer moles than PM LT and up to 50 times fewer moles than the B subunit. These observations indicate that, on the basis of molar equivalents, the holotoxin (which contains one A plus five or six B subunits) is a more potent immunogen than either PM LT (which contains one A and probably one B subunit) or the B subunit. PMID:7011990

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

2015-01-01

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.

Ingestion of transgenic carrots expressing the Escherichia coli heat-labile enterotoxin B subunit protects mice against cholera toxin challenge.

PubMed

Rosales-Mendoza, Sergio; Soria-Guerra, Ruth Elena; López-Revilla, Rubén; Moreno-Fierros, Leticia; Alpuche-Solís, Angel Gabriel

2008-01-01

Diarrheal diseases caused by Vibrio cholerae and enterotoxigenic Escherichia coli (ETEC) are worldwide health problems that might be prevented with vaccines based on edible plants expressing the B subunit from either the cholera toxin (CTB) or the E. coli heat labile toxin (LTB). In this work we analyzed the immunity induced in Balb/c mice by ingestion of three weekly doses of 10 mug of LTB derived from transgenic carrot material. Although the anti-LTB serum immunoglobulin G (IgG) and intestinal IgA antibody responses were higher with 10 mug-doses of pure bacterial recombinant LTB (rLTB), the transgenic carrot material also elicited significant serum and intestinal antibody responses. Serum anti-LTB IgG1 antibodies predominated over IgG2a antibodies, suggesting that mainly Th2 responses were induced. A decrease of intestinal fluid accumulation after cholera toxin challenge was observed in mice immunized with either rLTB or LTB-containing carrot material. These results demonstrate that ingestion of carrot-derived LTB induces antitoxin systemic and intestinal immunity in mice and suggest that transgenic carrots expressing LTB may be used as an effective edible vaccine against cholera and ETEC diarrhea in humans.

Expression of Chlamydophila psittaci MOMP heat-labile toxin B subunit fusion gene in transgenic rice.

PubMed

Zhang, Xiuxiang; Yuan, Ziguo; Guo, Xuejun; Li, Jingwen; Li, Zhaonan; Wang, Qingyu

2008-09-01

A DNA fragment encoding the MOMP gene of Chlamydophila psittaci was fused to the heat-labile toxin B subunit gene (LTB-MOMP) and transferred into rice callus by Agrobacterium tumefaciens-mediated transformation. The LTB-MOMP fusion gene was detected in genomic DNA from transformed rice leaves by Southern blot and RT-PCR amplification. Synthesis and assembly of the LTB-MOMP fusion protein into pentamers was detected in transformed leaf extracts by immunoblot analysis. Binding of the pentamers to intestinal epithelial cell membrane glycolipid receptors was quantified by GM1-ganglioside enzyme-linked immunosorbent assay (GM1-ELISA). The ELISA results indicated that LTB-MOMP fusion protein made up 0.0033-0.0054% of the total soluble leaf protein. Meanwhile, this suggested that the fusion protein retained both its native antigenicity and the ability to form pentamers.

Effects of Altering Levothyroxine (L-T4) Doses on Quality of Life, Mood, and Cognition in L-T4 Treated Subjects.

PubMed

Samuels, Mary H; Kolobova, Irina; Niederhausen, Meike; Janowsky, Jeri S; Schuff, Kathryn G

2018-05-01

The brain is a critical target organ for thyroid hormone, but it is unclear whether variations in thyroid function within and near the reference range affect quality of life, mood, or cognition. A total of 138 subjects with levothyroxine (L-T4)-treated hypothyroidism and normal thyrotropin (TSH) levels underwent measures of quality of life (36-Item Short Form Health Survey, Underactive Thyroid-Dependent Quality of Life Questionnaire), mood (Profile of Mood States, Affective Lability Scale), and cognition (executive function, memory). They were then randomly assigned to receive an unchanged, higher, or lower L-T4 dose in double-blind fashion, targeting one of three TSH ranges (0.34 to 2.50, 2.51 to 5.60, or 5.61 to 12.0 mU/L). Doses were adjusted every 6 weeks based on TSH levels. Baseline measures were reassessed at 6 months. At the end of the study, by intention to treat, mean L-T4 doses were 1.50 ± 0.07, 1.32 ± 0.07, and 0.78 ± 0.08 μg/kg (P < 0.001), and mean TSH levels were 1.85 ± 0.25, 3.93 ± 0.38, and 9.49 ± 0.80 mU/L (P < 0.001), respectively, in the three arms. There were minor differences in a few outcomes between the three arms, which were no longer significant after correction for multiple comparisons. Subjects could not ascertain how their L-T4 doses had been adjusted (P = 0.55) but preferred L-T4 doses they perceived to be higher (P < 0.001). Altering L-T4 doses in hypothyroid subjects to vary TSH levels in and near the reference range does not affect quality of life, mood, or cognition. L-T4-treated subjects prefer perceived higher L-T4 doses despite a lack of objective benefit. Adjusting L-T4 doses in hypothyroid patients based on symptoms in these areas may not result in significant clinical improvement.

Attenuated Escherichia coli strains expressing the colonization factor antigen I (CFA/I) and a detoxified heat-labile enterotoxin (LThK63) enhance clearance of ETEC from the lungs of mice and protect mice from intestinal ETEC colonization and LT-induced fluid accumulation.

PubMed

Byrd, Wyatt; Boedeker, Edgar C

2013-03-15

Although enterotoxigenic Escherichia coli (ETEC) infections are important causes of infantile and traveler's diarrhea there is no licensed vaccine available for those at-risk. Our goal is to develop a safe, live attenuated ETEC vaccine. We used an attenuated E. coli strain (O157:H7, Δ-intimin, Stx1-neg, Stx2-neg) as a vector (ZCR533) to prepare two vaccine strains, one strain expressing colonization factor antigen I (ZCR533-CFA/I) and one strain expressing CFA/I and a detoxified heat-labile enterotoxin (ZCR533-CFA/I+LThK63) to deliver ETEC antigens to mucosal sites in BALB/c mice. Following intranasal and intragastric immunization with the vaccine strains, serum IgG and IgA antibodies were measured to the CFA/I antigen, however, only serum IgG antibodies were detected to the heat-labile enterotoxin. Intranasal administration of the vaccine strains induced respiratory and intestinal antibody responses to the CFA/I and LT antigens, while intragastric administration induced only intestinal antibody responses with no respiratory antibodies detected to the CFA/I and LT antigens. Mice immunized intranasally with the vaccine strains showed enhanced clearance of wild-type (wt) ETEC bacteria from the lungs. Mice immunized intranasally and intragastrically with the vaccine strains were protected from intestinal colonization following oral challenge with ETEC wt bacteria. Mice immunized intragastrically with the ZCR533-CFA/I+LThK63 vaccine strain had less fluid accumulate in their intestine following challenge with ETEC wt bacteria or with purified LT as compared to the sham mice indicating that the immunized mice were protected from LT-induced intestinal fluid accumulation. Thus, mice intragastrically immunized with the ZCR533-CFA/I+LThK63 vaccine strain were able to effectively neutralize the activity of the LT enterotoxin. However, no difference in intestinal fluid accumulation was detected in the mice immunized intranasally with the vaccine strain as compared to the sham

Susceptibility to anthrax lethal toxin-induced rat death is controlled by a single chromosome 10 locus that includes rNlrp1.

PubMed

Newman, Zachary L; Printz, Morton P; Liu, Shihui; Crown, Devorah; Breen, Laura; Miller-Randolph, Sharmina; Flodman, Pamela; Leppla, Stephen H; Moayeri, Mahtab

2010-05-20

Anthrax lethal toxin (LT) is a bipartite protease-containing toxin and a key virulence determinant of Bacillus anthracis. In mice, LT causes the rapid lysis of macrophages isolated from certain inbred strains, but the correlation between murine macrophage sensitivity and mouse strain susceptibility to toxin challenge is poor. In rats, LT induces a rapid death in as little as 37 minutes through unknown mechanisms. We used a recombinant inbred (RI) rat panel of 19 strains generated from LT-sensitive and LT-resistant progenitors to map LT sensitivity in rats to a locus on chromosome 10 that includes the inflammasome NOD-like receptor (NLR) sensor, Nlrp1. This gene is the closest rat homolog of mouse Nlrp1b, which was previously shown to control murine macrophage sensitivity to LT. An absolute correlation between in vitro macrophage sensitivity to LT-induced lysis and animal susceptibility to the toxin was found for the 19 RI strains and 12 additional rat strains. Sequencing Nlrp1 from these strains identified five polymorphic alleles. Polymorphisms within the N-terminal 100 amino acids of the Nlrp1 protein were perfectly correlated with LT sensitivity. These data suggest that toxin-mediated lethality in rats as well as macrophage sensitivity in this animal model are controlled by a single locus on chromosome 10 that is likely to be the inflammasome NLR sensor, Nlrp1.

Chloroquine derivatives block the translocation pores and inhibit cellular entry of Clostridium botulinum C2 toxin and Bacillus anthracis lethal toxin.

PubMed

Kreidler, Anna-Maria; Benz, Roland; Barth, Holger

2017-03-01

The pathogenic bacteria Clostridium botulinum and Bacillus anthracis produce the binary protein toxins C2 and lethal toxin (LT), respectively. These toxins consist of a binding/transport (B 7 ) component that delivers the separate enzyme (A) component into the cytosol of target cells where it modifies its specific substrate and causes cell death. The B 7 components of C2 toxin and LT, C2IIa and PA 63 , respectively, are ring-shaped heptamers that bind to their cellular receptors and form complexes with their A components C2I and lethal factor (LF), respectively. After receptor-mediated endocytosis of the toxin complexes, C2IIa and PA 63 insert into the membranes of acidified endosomes and form trans-membrane pores through which C2I and LF translocate across endosomal membranes into the cytosol. C2IIa and PA 63 also form channels in planar bilayer membranes, and we used this approach earlier to identify chloroquine as a potent blocker of C2IIa and PA 63 pores. Here, a series of chloroquine derivatives was investigated to identify more efficient toxin inhibitors with less toxic side effects. Chloroquine, primaquine, quinacrine, and fluphenazine blocked C2IIa and PA 63 pores in planar lipid bilayers and in membranes of living epithelial cells and macrophages, thereby preventing the pH-dependent membrane transport of the A components into the cytosol and protecting cells from intoxication with C2 toxin and LT. These potent inhibitors of toxin entry underline the central role of the translocation pores for cellular uptake of binary bacterial toxins and as relevant drug targets, and might be lead compounds for novel pharmacological strategies against severe enteric diseases and anthrax.

Peroral Immunization of Rats with Escherichia coli Heat-Labile Enterotoxin Delivered by Microspheres

PubMed Central

Klipstein, Frederick A.; Engert, Richard F.; Sherman, William T.

1983-01-01

The antigenicity of the Escherichia coli heat-labile enterotoxin was not protected against the adverse effect of gastric acidity when the toxin was given together with bicarbonate for peroral immunization to rats, but immunization with the heat-labile enterotoxin encapsulated in pH-dependent microspheres aroused the same strong degree of serum and mucosal antitoxin responses and of protection against challenge as was achieved by peroral immunization after ablation of gastric secretions by pretreatment with cimetidine. PMID:6339378

Noninvasive Imaging Technologies Reveal Edema Toxin as a Key Virulence Factor in Anthrax

PubMed Central

Dumetz, Fabien; Jouvion, Grégory; Khun, Huot; Glomski, Ian Justin; Corre, Jean-Philippe; Rougeaux, Clémence; Tang, Wei-Jen; Mock, Michèle; Huerre, Michel; Goossens, Pierre Louis

2011-01-01

Powerful noninvasive imaging technologies enable real-time tracking of pathogen-host interactions in vivo, giving access to previously elusive events. We visualized the interactions between wild-type Bacillus anthracis and its host during a spore infection through bioluminescence imaging coupled with histology. We show that edema toxin plays a central role in virulence in guinea pigs and during inhalational infection in mice. Edema toxin (ET), but not lethal toxin (LT), markedly modified the patterns of bacterial dissemination leading, to apparent direct dissemination to the spleen and provoking apoptosis of lymphoid cells. Each toxin alone provoked particular histological lesions in the spleen. When ET and LT are produced together during infection, a specific temporal pattern of lesion developed, with early lesions typical of LT, followed at a later stage by lesions typical of ET. Our study provides new insights into the complex spatial and temporal effects of B. anthracis toxins in the infected host, suggesting a greater role than previously suspected for ET in anthrax and suggesting that therapeutic targeting of ET contributes to protection. PMID:21641378

Noninvasive imaging technologies reveal edema toxin as a key virulence factor in anthrax.

PubMed

Dumetz, Fabien; Jouvion, Grégory; Khun, Huot; Glomski, Ian Justin; Corre, Jean-Philippe; Rougeaux, Clémence; Tang, Wei-Jen; Mock, Michèle; Huerre, Michel; Goossens, Pierre Louis

2011-06-01

Powerful noninvasive imaging technologies enable real-time tracking of pathogen-host interactions in vivo, giving access to previously elusive events. We visualized the interactions between wild-type Bacillus anthracis and its host during a spore infection through bioluminescence imaging coupled with histology. We show that edema toxin plays a central role in virulence in guinea pigs and during inhalational infection in mice. Edema toxin (ET), but not lethal toxin (LT), markedly modified the patterns of bacterial dissemination leading, to apparent direct dissemination to the spleen and provoking apoptosis of lymphoid cells. Each toxin alone provoked particular histological lesions in the spleen. When ET and LT are produced together during infection, a specific temporal pattern of lesion developed, with early lesions typical of LT, followed at a later stage by lesions typical of ET. Our study provides new insights into the complex spatial and temporal effects of B. anthracis toxins in the infected host, suggesting a greater role than previously suspected for ET in anthrax and suggesting that therapeutic targeting of ET contributes to protection. Copyright © 2011 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.

Prolonged protection against Intranasal challenge with influenza virus following systemic immunization or combinations of mucosal and systemic immunizations with a heat-labile toxin mutant.

PubMed

Zhou, Fengmin; Goodsell, Amanda; Uematsu, Yasushi; Vajdy, Michael

2009-04-01

Seasonal influenza virus infections cause considerable morbidity and mortality in the world, and there is a serious threat of a pandemic influenza with the potential to cause millions of deaths. Therefore, practical influenza vaccines and vaccination strategies that can confer protection against intranasal infection with influenza viruses are needed. In this study, we demonstrate that using LTK63, a nontoxic mutant of the heat-labile toxin from Escherichia coli, as an adjuvant for both mucosal and systemic immunizations, systemic (intramuscular) immunization or combinations of mucosal (intranasal) and intramuscular immunizations protected mice against intranasal challenge with a lethal dose of live influenza virus at 3.5 months after the second immunization.

Enterotoxigenic Escherichia coli Adhesin-Toxoid Multiepitope Fusion Antigen CFA/I/II/IV-3xSTaN12S-mnLTG192G/L211A-Derived Antibodies Inhibit Adherence of Seven Adhesins, Neutralize Enterotoxicity of LT and STa Toxins, and Protect Piglets against Diarrhea.

PubMed

Nandre, Rahul; Ruan, Xiaosai; Lu, Ti; Duan, Qiangde; Sack, David; Zhang, Weiping

2018-03-01

Enterotoxigenic Escherichia coli (ETEC) strains are a leading cause of children's diarrhea and travelers' diarrhea. Vaccines inducing antibodies to broadly inhibit bacterial adherence and to neutralize toxin enterotoxicity are expected to be effective against ETEC-associated diarrhea. 6×His-tagged adhesin-toxoid fusion proteins were shown to induce neutralizing antibodies to several adhesins and LT and STa toxins (X. Ruan, D. A. Sack, W. Zhang, PLoS One 10:e0121623, 2015, https://doi.org/10.1371/journal.pone.0121623). However, antibodies derived from His-tagged CFA/I/II/IV-2xSTa A14Q -dmLT or CFA/I/II/IV-2xSTa N12S -dmLT protein were less effective in neutralizing STa enterotoxicity and were not evaluated in vivo for efficacy against ETEC diarrhea. Additionally, His-tagged proteins are considered less desirable for human vaccines. In this study, we produced a tagless adhesin-toxoid MEFA (multiepitope fusion antigen) protein, enhanced anti-STa immunogenicity by including a third copy of STa toxoid STa N12S , and examined antigen immunogenicity in a murine model. Moreover, we immunized pregnant pigs with the tagless adhesin-toxoid MEFA protein and evaluated passive antibody protection against STa + or LT + ETEC infection in a pig challenge model. Results showed that tagless adhesin-toxoid MEFA CFA/I/II/IV-3xSTa N12S -mnLT R192G/L211A induced broad antiadhesin and antitoxin antibody responses in the intraperitoneally immunized mice and the intramuscularly immunized pigs. Mouse and pig serum antibodies significantly inhibited adherence of seven colonization factor antigen (CFA) adhesins (CFA/I and CS1 to CS6) and effectively neutralized both toxins. More importantly, suckling piglets born to the immunized mothers acquired antibodies and were protected against STa + ETEC and LT + ETEC diarrhea. These results indicated that tagless CFA/I/II/IV-3xSTa N12S -mnLT R192G/L211A induced broadly protective antiadhesin and antitoxin antibodies and demonstrate that this adhesin

Quantitative Determination of Lethal Toxin Proteins in Culture Supernatant of Human Live Anthrax Vaccine Bacillus anthracis A16R

PubMed Central

Zai, Xiaodong; Zhang, Jun; Liu, Ju; Liu, Jie; Li, Liangliang; Yin, Ying; Fu, Ling; Xu, Junjie; Chen, Wei

2016-01-01

Bacillus anthracis (B. anthracis) is the etiological agent of anthrax affecting both humans and animals. Anthrax toxin (AT) plays a major role in pathogenesis. It includes lethal toxin (LT) and edema toxin (ET), which are formed by the combination of protective antigen (PA) and lethal factor (LF) or edema factor (EF), respectively. The currently used human anthrax vaccine in China utilizes live-attenuated B. anthracis spores (A16R; pXO1+, pXO2−) that produce anthrax toxin but cannot produce the capsule. Anthrax toxins, especially LT, have key effects on both the immunogenicity and toxicity of human anthrax vaccines. Thus, determining quantities and biological activities of LT proteins expressed by the A16R strain is meaningful. Here, we explored LT expression patterns of the A16R strain in culture conditions using another vaccine strain Sterne as a control. We developed a sandwich ELISA and cytotoxicity-based method for quantitative detection of PA and LF. Expression and degradation of LT proteins were observed in culture supernatants over time. Additionally, LT proteins expressed by the A16R and Sterne strains were found to be monomeric and showed cytotoxic activity, which may be the main reason for side effects of live anthrax vaccines. Our work facilitates the characterization of anthrax vaccines components and establishment of a quality control standard for vaccine production which may ultimately help to ensure the efficacy and safety of the human anthrax vaccine A16R. PMID:26927174

Quantitative Determination of Lethal Toxin Proteins in Culture Supernatant of Human Live Anthrax Vaccine Bacillus anthracis A16R.

PubMed

Zai, Xiaodong; Zhang, Jun; Liu, Ju; Liu, Jie; Li, Liangliang; Yin, Ying; Fu, Ling; Xu, Junjie; Chen, Wei

2016-02-25

Bacillus anthracis (B. anthracis) is the etiological agent of anthrax affecting both humans and animals. Anthrax toxin (AT) plays a major role in pathogenesis. It includes lethal toxin (LT) and edema toxin (ET), which are formed by the combination of protective antigen (PA) and lethal factor (LF) or edema factor (EF), respectively. The currently used human anthrax vaccine in China utilizes live-attenuated B. anthracis spores (A16R; pXO1+, pXO2-) that produce anthrax toxin but cannot produce the capsule. Anthrax toxins, especially LT, have key effects on both the immunogenicity and toxicity of human anthrax vaccines. Thus, determining quantities and biological activities of LT proteins expressed by the A16R strain is meaningful. Here, we explored LT expression patterns of the A16R strain in culture conditions using another vaccine strain Sterne as a control. We developed a sandwich ELISA and cytotoxicity-based method for quantitative detection of PA and LF. Expression and degradation of LT proteins were observed in culture supernatants over time. Additionally, LT proteins expressed by the A16R and Sterne strains were found to be monomeric and showed cytotoxic activity, which may be the main reason for side effects of live anthrax vaccines. Our work facilitates the characterization of anthrax vaccines components and establishment of a quality control standard for vaccine production which may ultimately help to ensure the efficacy and safety of the human anthrax vaccine A16R.

The three-dimensional crystal structure of cholera toxin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Rong-Guang; Westbrook, M.L.; Nance, S.

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.

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

PubMed Central

Guichard, Annabel; Nizet, Victor; Bier, Ethan

2013-01-01

The anthrax toxins lethal toxin (LT) and edema toxin (ET), are essential virulence factors produced by B. 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 of the disease bacteria disseminate via a hematological route to various target tissues and organs, which are typically highly vascularized. As bacteria proliferate in the bloodstream LT and ET begin to accumulate rapidly reaching a critical threshold level that will cause death even when the bacterial proliferation is curtailed by antibiotics. During this final phase of infection the toxins cause an increase in vascular permeability and a decrease in function of target organs including the heart, spleen, kidney, adrenal gland, and brain. In this review, we examine the various biological effects of anthrax toxins, focusing on the fulminant stage of the disease and on mechanisms by which the two toxins may collaborate to cause cardiovascular collapse. We discuss normal mechanisms involved in maintaining vascular integrity and based on recent studies indicating that LT and ET cooperatively inhibit membrane trafficking to cell-cell junctions we explore several potential mechanisms by which the toxins may achieve their lethal effects. We also summarize the effects of other potential virulence factors secreted by B. anthracis and consider the role of toxic factors in the evolutionarily recent emergence of this devastating disease. PMID:21930233

Immunologic Interrelationships of Coliform Heat-Labile and Heat-Stable Enterotoxins

DTIC Science & Technology

1980-01-15

PUBLICATIONS Supported by Contract No. DAMD 17-77-C-7032 1. Klipstein FA, Engert RF: Immunological interrelationships between cholera toxin and the...heat-labile and heat-stable enterotoxins of coliform bacteria. Infec Immun 18:110, 1977 2. Klipstein FA, Engert RF: Immunological relationship of...different preparations of coliform enterotoxins. Infec Immun 21:771, 1978 3. Klipstein FA, Engert RF: Reversal of jejunal water secretion by glucose in

Immunological Interrelationships of Coliform Heat-Labile and Heat-Stable Enterotoxins

DTIC Science & Technology

1981-01-01

FA, Engert RF: Immunological interrelationships between cholera toxin and the heat-labile and heat-stable enterotoxins of coliforn, bacteria. Infec...Irnmun 18:110, 1977 2. Klipstein FA, Engert RF: Immunological relaticnsh~p of different preparations of coliform enterotoxins. Infec Immun 21:771, 1918...3 Klipstein FA, Engert RF: Reversal of jejunal water secretion by glucose in rats exposed to coliform enterotoxcins. Gastroenterology 75:255, 1978 4

Immunological Interrelationships of Coliform Heat-Labile and Heat-Stable Enterotoxins

DTIC Science & Technology

1981-09-01

FA, Engert RF: Immunological interrelationships between cholera toxin and the heat -labile and hoat-stable enterotoxins of coliform bacteria. Infec...Immun 18:110, 1977 2. Klipstein FA, Engert RF: Immunological relationship of different preparations of coliform enterotoxins. Infec Immun 21:771, 1978...3. Klipstein FA, Engert RF: Reversal of jejunal water secretion by glucose in rats exposed to coliform enterotoxins. Gastroenteroloj y 75:255, 1978 4

Bacillus anthracis lethal toxin induces TNF-α–independent hypoxia-mediated toxicity in mice

PubMed Central

Moayeri, Mahtab; Haines, Diana; Young, Howard A.; Leppla, Stephen H.

2003-01-01

Bacillus anthracis lethal toxin (LT) is the major virulence factor of anthrax and reproduces most of the laboratory manifestations of the disease in animals. We studied LT toxicity in BALB/cJ and C57BL/6J mice. BALB/cJ mice became terminally ill earlier and with higher frequency than C57BL/6J mice. Timed histopathological analysis identified bone marrow, spleen, and liver as major affected organs in both mouse strains. LT induced extensive hypoxia. Crisis was due to extensive liver necrosis accompanied by pleural edema. There was no evidence of disseminated intravascular coagulation or renal dysfunction. Instead, analyses revealed hepatic dysfunction, hypoalbuminemia, and vascular/oxygenation insufficiency. Of 50 cytokines analyzed, BALB/cJ mice showed rapid but transitory increases in specific factors including KC, MCP-1/JE, IL-6, MIP-2, G-CSF, GM-CSF, eotaxin, FasL, and IL-1β. No changes in TNF-α occurred. The C57BL/6J mice did not mount a similar cytokine response. These factors were not induced in vitro by LT treatment of toxin-sensitive macrophages. The evidence presented shows that LT kills mice through a TNF-α–independent, FasL-independent, noninflammatory mechanism that involves hypoxic tissue injury but does not require macrophage sensitivity to toxin. PMID:12952916

Role of the protective antigen octamer in the molecular mechanism of anthrax lethal toxin stabilization in plasma

PubMed Central

Kintzer, Alexander F.; Sterling, Harry J.; Tang, Iok I.; Abdul-Gader, Ali; Miles, Andrew J.; Wallace, B. A.; Williams, Evan R.; Krantz, Bryan A.

2010-01-01

Anthrax is caused by strains of Bacillus anthracis that produce two key virulence factors, anthrax toxin (Atx) and a poly-γ-D-glutamic acid capsule. Atx is comprised of three-proteins: protective antigen (PA) and two enzymes, lethal factor (LF) and edema factor (EF). To disrupt cell function, these components must assemble into holotoxin complexes, which contain either a ring-shaped homooctameric or homoheptameric PA oligomer bound to multiple copies of either LF and/or EF, producing lethal toxin (LT), edema toxin, or mixtures thereof. Once a host cell endocytoses these complexes, PA converts into a membrane-inserted channel that translocates LF and EF into the cytosol. LT may assemble on host cell surfaces or extracellularly in plasma. We show that under physiological conditions in bovine plasma that LT complexes containing heptameric PA aggregate and inactivate more readily than LT complexes containing octameric PA. LT complexes containing octameric PA possess enhanced stability, channel forming activity, and macrophage cytotoxicity relative to those containing heptameric PA. Under physiological conditions, multiple biophysical probes reveal that heptameric PA can prematurely adopt the channel conformation, but octameric PA complexes remain in their soluble prechannel configuration allowing them to resist aggregation and inactivation. We conclude that PA may form an octameric oligomeric state as a means to produce a more stable and active LT complex that may circulate freely in the blood. PMID:20433851

Effects of Site-Directed Mutagenesis of Escherichia coli Heat-Labile Enterotoxin on ADP-Ribosyltransferase Activity and Interaction with ADP-Ribosylation Factors

PubMed Central

A. Stevens, Linda; Moss, Joel; Vaughan, Martha; Pizza, Mariagrazia; Rappuoli, Rino

1999-01-01

Escherichia coli heat-labile enterotoxin (LT), an oligomeric protein with one A subunit (LTA) and five B subunits, exerts its effects via the ADP-ribosylation of Gsα, a guanine nucleotide-binding (G) protein that activates adenylyl cyclase. LTA also ADP-ribosylates simple guanidino compounds (e.g., arginine) and catalyzes its own auto-ADP-ribosylation. All LTA-catalyzed reactions are enhanced by ADP-ribosylation factors (ARFs), 20-kDa guanine nucleotide-binding proteins. Replacement of arginine-7 (R7K), valine-53 (V53D), serine-63 (S63K), valine 97 (V97K), or tyrosine-104 (Y104K) in LTA resulted in fully assembled but nontoxic proteins. S63K, V53D, and R7K are catalytic-site mutations, whereas V97K and Y104K are amino acid replacements adjacent to and outside of the catalytic site, respectively. The effects of mutagenesis were quantified by measuring ADP-ribosyltransferase activity (i.e., auto-ADP-ribosylation and ADP-ribosylagmatine synthesis) and interaction with ARF (i.e., inhibition of ARF-stimulated cholera toxin ADP-ribosyltransferase activity and effects of ARF on mutant auto-ADP-ribosylation). All mutants were inactive in the ADP-ribosyltransferase assay; however, auto-ADP-ribosylation in the presence of recombinant human ARF6 was detected, albeit much less than that of native LT (Y104K > V53D > V97K > R7K, S63K). Based on the lack of inhibition by free ADP-ribose, the observed auto-ADP-ribosylation activity was enzymatic and not due to the nonenzymatic addition of free ADP-ribose. V53D, S63K, and R7K were more effective than Y104K or V97K in blocking ARF stimulation of cholera toxin ADP-ribosyltransferase. Based on these data, it appears that ARF-binding and catalytic sites are not identical and that a region outside the NAD cleft may participate in the LTA-ARF interaction. PMID:9864224

Influence of Host Interleukin-10 Polymorphisms on Development of Traveler's Diarrhea Due to Heat-Labile Enterotoxin-Producing Escherichia coli in Travelers from the United States Who Are Visiting Mexico▿

PubMed Central

Flores, Jose; DuPont, Herbert L.; Lee, Stephanie A.; Belkind-Gerson, Jaime; Paredes, Mercedes; Mohamed, Jamal A.; Armitige, Lisa Y.; Guo, Dong-Chuan; Okhuysen, Pablo C.

2008-01-01

Up to 60% of U.S. visitors to Mexico develop traveler's diarrhea (TD), mostly due to enterotoxigenic Escherichia coli (ETEC) strains that produce heat-labile (LT) and/or heat-stable (ST) enterotoxins. Distinct single-nucleotide polymorphisms (SNPs) within the interleukin-10 (IL-10) promoter have been associated with high, intermediate, or low production of IL-10. We conducted a prospective study to investigate the association of SNPs in the IL-10 promoter and the occurrence of TD in ETEC LT-exposed travelers. Sera from U.S. travelers to Mexico collected on arrival and departure were studied for ETEC LT seroconversion by using cholera toxin as the antigen. Pyrosequencing was performed to genotype IL-10 SNPs. Stools from subjects who developed diarrhea were also studied for other enteropathogens. One hundred twenty-one of 569 (21.3%) travelers seroconverted to ETEC LT, and among them 75 (62%) developed diarrhea. Symptomatic seroconversion was more commonly seen in subjects who carried a genotype producing high levels of IL-10; it was seen in 83% of subjects with the GG genotype versus 54% of subjects with the AA genotype at IL-10 gene position −1082 (P, 0.02), in 71% of those with the CC genotype versus 33% of those with the TT genotype at position −819 (P, 0.005), and in 71% of those with the CC genotype versus 38% of those with the AA genotype at position −592 (P, 0.02). Travelers with the GCC haplotype were more likely to have symptomatic seroconversion than those with the ATA haplotype (71% versus 38%; P, 0.002). Travelers genetically predisposed to produce high levels of IL-10 were more likely to experience symptomatic ETEC TD. PMID:18579697

Influence of host interleukin-10 polymorphisms on development of traveler's diarrhea due to heat-labile enterotoxin-producing Escherichia coli in travelers from the United States who are visiting Mexico.

PubMed

Flores, Jose; DuPont, Herbert L; Lee, Stephanie A; Belkind-Gerson, Jaime; Paredes, Mercedes; Mohamed, Jamal A; Armitige, Lisa Y; Guo, Dong-Chuan; Okhuysen, Pablo C

2008-08-01

Up to 60% of U.S. visitors to Mexico develop traveler's diarrhea (TD), mostly due to enterotoxigenic Escherichia coli (ETEC) strains that produce heat-labile (LT) and/or heat-stable (ST) enterotoxins. Distinct single-nucleotide polymorphisms (SNPs) within the interleukin-10 (IL-10) promoter have been associated with high, intermediate, or low production of IL-10. We conducted a prospective study to investigate the association of SNPs in the IL-10 promoter and the occurrence of TD in ETEC LT-exposed travelers. Sera from U.S. travelers to Mexico collected on arrival and departure were studied for ETEC LT seroconversion by using cholera toxin as the antigen. Pyrosequencing was performed to genotype IL-10 SNPs. Stools from subjects who developed diarrhea were also studied for other enteropathogens. One hundred twenty-one of 569 (21.3%) travelers seroconverted to ETEC LT, and among them 75 (62%) developed diarrhea. Symptomatic seroconversion was more commonly seen in subjects who carried a genotype producing high levels of IL-10; it was seen in 83% of subjects with the GG genotype versus 54% of subjects with the AA genotype at IL-10 gene position -1082 (P, 0.02), in 71% of those with the CC genotype versus 33% of those with the TT genotype at position -819 (P, 0.005), and in 71% of those with the CC genotype versus 38% of those with the AA genotype at position -592 (P, 0.02). Travelers with the GCC haplotype were more likely to have symptomatic seroconversion than those with the ATA haplotype (71% versus 38%; P, 0.002). Travelers genetically predisposed to produce high levels of IL-10 were more likely to experience symptomatic ETEC TD.

Analysis of immune response in young and aged mice vaccinated with corn-derived antigen against Escherichia coli heat-labile enterotoxin.

PubMed

Karaman, Sule; Cunnick, Joan; Wang, Kan

2006-01-01

Enterotoxigenic strains of Escherichia coli produce a heat-labile holotoxin (LT), which causes diarrhea. We engineered corn seeds to produce LT-B, the nontoxic subunit of LT, to serve as a plant-derived vaccine to traveler's diarrhea and as an adjuvant for co-administered proteins. We previously demonstrated that a strong mucosal and systemic antibody response is elicited in young mice with oral administration of corn-derived LT-B. The present study examined systemic and mucosal antibody responses to LT-B in young and aged mice, and recall responses to oral administration and injection of LT-B in aged mice. Specific IgA and IgG antibodies were detectable during an 11-mo period, although the concentration of antigen-specific antibodies declined gradually. Booster by feeding or injection dramatically increased the concentration of specific IgA from that seen in young mice. Specific IgG levels were boosted to concentrations similar to those in young mice. This effect may be age-dependent and related to prior immunization exposure. Analysis of the antibody response of naïve aged mice against corn-derived LT-B demonstrated an age-related suppression in specific IgG production, but not specific IgA. These results may provide important information for edible vaccine strategies for young and aged individuals.

Partial purification of a toxin found in hamsters with antibiotic-associated colitis. Reversible binding of the toxin by cholestyramine.

PubMed

Humphrey, C D; Condon, C W; Cantey, J R; Pittman, F E

1979-03-01

A toxin with cytotoxic and enterotoxic activities was isolated from cecal contents of hamsters receiving lincomycin. The toxin was partially purified by ultracentrifugation, ultrafiltration, (NH4)2SO4 precipitation, and gel filtration. Cytotoxic activity, assayed on monolayers of HeLa cells, was restricted to material that eluted in the molecular weight range of 107,000 +/- 6,000 daltons. Cytotoxicity of crude AAC toxin could be demonstrated at concentrations as low as 0.04 microgram/ml. The toxin was heat labile (55 degrees-60 degrees C for 0.5 hr) and sensitive to trypsinization, acidification at pH 3, or alkalinization at pH 9. Cytotoxic activity was inhibited by Clostridium sordellii antitoxin. Enterotoxic activity of the crude toxin and the cytotoxic fraction from gel filtration was demonstrated by fluid secretion in ligated rabbit ileal loops. Studies were done in vitro with cholestyramine resin, vancomycin, or gentamicin to determine if the toxin was bound or denatured by these drugs. It was demonstrated that cholestyramine bound the toxin, significantly reducing its cytotoxicity. Reversible binding of the cytotoxic material was demonstrated by salt gradient elution. Neither vancomycin nor gentamicin had any effect on the in vitro cytotoxic activity of the toxin.

Bacillus anthracis Cell Wall Peptidoglycan but Not Lethal or Edema Toxins Produces Changes Consistent With Disseminated Intravascular Coagulation in a Rat Model

PubMed Central

Qiu, Ping; Li, Yan; Shiloach, Joseph; Cui, Xizhong; Sun, Junfeng; Trinh, Loc; Kubler-Kielb, Joanna; Vinogradov, Evgeny; Mani, Haresh; Al-Hamad, Mariam; Fitz, Yvonne; Eichacker, Peter Q.

2013-01-01

Background. Disseminated intravascular coagulation (DIC) appears to be important in the pathogenesis of Bacillus anthracis infection, but its causes are unclear. Although lethal toxin (LT) and edema toxin (ET) could contribute, B. anthracis cell wall peptidoglycan (PGN), not the toxins, stimulates inflammatory responses associated with DIC. Methods and Results. To better understand the pathogenesis of DIC during anthrax, we compared the effects of 24-hour infusions of PGN, LT, ET, or diluent (control) on coagulation measures 6, 24, or 48 hours after infusion initiation in 135 rats. No control recipient died. Lethality rates (approximately 30%) did not differ among PGN, LT, and ET recipients (P = .78). Thirty-three of 35 deaths (94%) occurred between 6 and 24 hours after the start of challenge. Among challenge components, PGN most consistently altered coagulation measures. Compared with control at 6 hours, PGN decreased platelet and fibrinogen levels and increased prothrombin and activated partial thromboplastin times and tissue factor, tissue factor pathway inhibitor, protein C, plasminogen activator inhibitor (PAI), and thrombin-antithrombin complex levels, whereas LT and ET only decreased the fibrinogen level or increased the PAI level (P ≤ .05). Nearly all effects associated with PGN infusion significantly differed from changes associated with toxin infusion (P ≤ .05 for all comparisons except for PAI level). Conclusion. DIC during B. anthracis infection may be related more to components such as PGN than to LT or ET. PMID:23737601

Campylobacter jejuni chromosomal sequences that hybridize to Vibrio cholerae and Escherichia coli LT enterotoxin genes.

PubMed

Calva, E; Torres, J; Vázquez, M; Angeles, V; de la Vega, H; Ruíz-Palacios, G M

1989-02-20

Campylobacter jejuni is one of the main etiologic agents of gastrointestinal illness in developing and developed areas throughout the world. Isolation of enterotoxin-producing C. jejuni has been associated with clinical symptoms of a watery-secretory type of diarrhea. Although physiological and immunological relatedness has been demonstrated between the C. jejuni enterotoxin (CJT), the Vibrio cholerae enterotoxin (CT), and the heat-labile cholera-like Escherichia coli enterotoxin (LT), nucleotide sequence similarity between C. jejuni DNA and either the toxA, toxB, eltA or eltB genes remained to be shown. We found that binding to ganglioside GM1 prevented recognition of CJT by monoclonal antibodies directed to either CT or LT. This indicates antigenic similarity between the three enterotoxins in the ganglioside GM1-binding site. Therefore we searched for corresponding similarities at the DNA level and found, by oligodeoxynucleotide hybridization, C. jejuni chromosomal nucleotide sequences similar to the coding region for a postulated ganglioside GM1-binding site on toxB and eltB.

Protective Effect of Immunization with Heat-Labile Enterotoxin in Gnotobiotic Rats Monocontaminated with Enterotoxigenic Escherichia coli

PubMed Central

Klipstein, Frederick A.; Engert, Richard F.; Short, Helen B.

1980-01-01

The protective effect of active immunization with a purified preparation of the polymyxin-release form of Escherichia coli heat-labile enterotoxin (LT), administered using a parenteral prime and peroral boosts given after ablation of gastric secretion by means of cimetidine, was assessed in gnotobiotic rats which were challenged by monocontamination with enterotoxigenic strains of E. coli. Water transport was evaluated by the in vivo marker perfusion technique at weekly intervals over a 3-week period after contamination. Water transport in unimmunized control rats was consistently in absorption in those contaminated by a nontoxigenic strain, in secretion during only week 2 in those contaminated by an LT+/− strain, in secretion during weeks 2 and 3 in those contaminated by an LT+/ST+ (heat-stable enterotoxin) strain, and consistently in absorption in those contaminated by an −/ST+ strain. Rats immunized with a booster dosage of 250 μg had a significant increase (P < 0.001) in net water absorption as compared to unimmunized rats, with values in the borderline range of absorption, when challenged with either the LT+/− or LT+/ST+ strains. Rats immunized with a 10-fold-higher boosting dosage had a significant increase (P < 0.001) in net water absorption as compared to those boosted at the lower dosage; water absorption was within the normal range. There was no difference between the ileal bacterial counts of unimmunized and immunized rats challenged by the various strains. These observations indicate that this immunization program provides complete protection in an animal model against challenge by intestinal contamination with enterotoxigenic strains of E. coli which produce LT, either alone or in combination with ST. PMID:6991436

Bacterial toxin-antitoxin systems: more than selfish entities?

PubMed

Van Melderen, Laurence; Saavedra De Bast, Manuel

2009-03-01

Bacterial toxin-antitoxin (TA) systems are diverse and widespread in the prokaryotic kingdom. They are composed of closely linked genes encoding a stable toxin that can harm the host cell and its cognate labile antitoxin, which protects the host from the toxin's deleterious effect. TA systems are thought to invade bacterial genomes through horizontal gene transfer. Some TA systems might behave as selfish elements and favour their own maintenance at the expense of their host. As a consequence, they may contribute to the maintenance of plasmids or genomic islands, such as super-integrons, by post-segregational killing of the cell that loses these genes and so suffers the stable toxin's destructive effect. The function of the chromosomally encoded TA systems is less clear and still open to debate. This Review discusses current hypotheses regarding the biological roles of these evolutionarily successful small operons. We consider the various selective forces that could drive the maintenance of TA systems in bacterial genomes.

Prioritized LT Codes

NASA Technical Reports Server (NTRS)

Woo, Simon S.; Cheng, Michael K.

2011-01-01

The original Luby Transform (LT) coding scheme is extended to account for data transmissions where some information symbols in a message block are more important than others. Prioritized LT codes provide unequal error protection (UEP) of data on an erasure channel by modifying the original LT encoder. The prioritized algorithm improves high-priority data protection without penalizing low-priority data recovery. Moreover, low-latency decoding is also obtained for high-priority data due to fast encoding. Prioritized LT codes only require a slight change in the original encoding algorithm, and no changes at all at the decoder. Hence, with a small complexity increase in the LT encoder, an improved UEP and low-decoding latency performance for high-priority data can be achieved. LT encoding partitions a data stream into fixed-sized message blocks each with a constant number of information symbols. To generate a code symbol from the information symbols in a message, the Robust-Soliton probability distribution is first applied in order to determine the number of information symbols to be used to compute the code symbol. Then, the specific information symbols are chosen uniform randomly from the message block. Finally, the selected information symbols are XORed to form the code symbol. The Prioritized LT code construction includes an additional restriction that code symbols formed by a relatively small number of XORed information symbols select some of these information symbols from the pool of high-priority data. Once high-priority data are fully covered, encoding continues with the conventional LT approach where code symbols are generated by selecting information symbols from the entire message block including all different priorities. Therefore, if code symbols derived from high-priority data experience an unusual high number of erasures, Prioritized LT codes can still reliably recover both high- and low-priority data. This hybrid approach decides not only "how to encode

Molecular Characterization of Enterotoxigenic Escherichia coli Isolates Recovered from Children with Diarrhea during a 4-Year Period (2007 to 2010) in Bolivia

PubMed Central

Gonzales, Lucia; Sanchez, Samanta; Zambrana, Silvia; Wiklund, Gudrun; Svennerholm, Ann-Mari

2013-01-01

Enterotoxigenic Escherichia coli (ETEC) is an important cause of childhood diarrhea. This study aimed to characterize ETEC strains isolated from Bolivian children aged <5 years according to enterotoxin profile, colonization factors (CFs), suggested virulence genes, and severity of disease. A total of 299 ETEC isolates recovered from children with diarrhea and 55 ETEC isolates from children without diarrhea (controls) were isolated over a period of 4 years. Strains expressing heat-labile toxin (LT) or heat-stable toxin (ST) alone were about equally common and twice as common as ETEC producing both toxins (20%). ETEC strains expressing human ST (STh) were more common in children aged <2 years, while ETEC strains expressing LT plus STh (LT/STh) were more frequent in 2- to 5-year-old children. Severity of disease was not related to the toxin profile of the strains. CF-positive isolates were more frequently identified in diarrheal samples than in control samples (P = 0.02). The most common CFs were CFA/I and CS14. CFA/I ETEC strains were more frequent in children aged <2 years than CS1+CS3 isolates and CS14 isolates, which were more prevalent in 2- to 5-year-old children. The presence of suggested ETEC virulence genes (clyA, eatA, tia, tibC, leoA, and east-1) was not associated with disease. However, east-1 was associated with LT/STh strains (P < 0.001), eatA with STh strains (P < 0.001), and tia with LT/STh strains (P < 0.001). A minor seasonal peak of ETEC infections was identified in May during the cold-dry season and coincided with the peak of rotavirus infections; this pattern is unusual for ETEC and may be important for vaccination strategies in Bolivia. PMID:23390275

Combination L-T3 and L-T4 therapy for hypothyroidism.

PubMed

Wartofsky, Leonard

2013-10-01

Because of the longstanding controversy regarding whether hypothyroid patients can be optimally replaced by treatment with levothyroxine (L-T4) alone, numerous studies have addressed potential benefits of combined therapy of triiodothyronine (T3) with L-T4. Results of these studies have failed to support a potential benefit of combined therapy. A strong argument for the addition of L-T3 to L-T4 monotherapy has been lacking until recent genetic studies indicated a rationale for such therapy among a small fraction of the hypothyroid patient population. Interest in this issue has focused on the importance of the deiodinases in maintaining the euthyroid state and the role of genetic polymorphisms in the deiodinase genes that would affect thyroid hormone concentrations in both blood and tissues. One such polymorphism in the D2 gene, Thr92Ala, is associated with reduced T4 to T3 activation in skeletal muscle and thyroid, linked to obesity and alterations in thyroid-pituitary feedback, and in responses to thyroid hormone treatment. Although our professional organizations continue to recommend L-T4 alone for the treatment of hypothyroidism, the possibility of a D2 gene polymorphism should be considered in patients on L-T4 monotherapy who continue to complain of fatigue in spite of dosage achieving low normal serum thyroid stimulating hormone levels. A suggestive clue to the presence of this polymorphism could be a higher than normal free T4/free T3 ratio. Clinicians could consider adding T3 as a therapeutic trial in selected patients. Future well controlled clinical trials will be required to more fully resolve the controversy.

Activated protein C ameliorates Bacillus anthracis lethal toxin-induced lethal pathogenesis in rats

PubMed Central

2012-01-01

Background Lethal toxin (LT) is a major virulence factor of Bacillus anthracis. Sprague Dawley rats manifest pronounced lung edema and shock after LT treatments, resulting in high mortality. The heart failure that is induced by LT has been suggested to be a principal mechanism of lung edema and mortality in rodents. Since LT-induced death occurs more rapidly in rats than in mice, suggesting that other mechanisms in addition to the heart dysfunction may be contributed to the fast progression of LT-induced pathogenesis in rats. Coagulopathy may contribute to circulatory failure and lung injury. However, the effect of LT on coagulation-induced lung dysfunction is unclear. Methods To investigate the involvement of coagulopathy in LT-mediated pathogenesis, the mortality, lung histology and coagulant levels of LT-treated rats were examined. The effects of activated protein C (aPC) on LT-mediated pathogenesis were also evaluated. Results Fibrin depositions were detected in the lungs of LT-treated rats, indicating that coagulation was activated. Increased levels of plasma D-dimer and thrombomodulin, and the ameliorative effect of aPC further suggested that the activation of coagulation-fibrinolysis pathways plays a role in LT-mediated pathogenesis in rats. Reduced mortality was associated with decreased plasma levels of D-dimer and thrombomodulin following aPC treatments in rats with LT-mediated pathogenesis. Conclusions These findings suggest that the activation of coagulation in lung tissue contributes to mortality in LT-mediated pathogenesis in rats. In addition, anticoagulant aPC may help to develop a feasible therapeutic strategy. PMID:23170801

Binding to Gangliosides Containing N-Acetylneuraminic Acid Is Sufficient To Mediate the Immunomodulatory Properties of the Nontoxic Mucosal Adjuvant LT-IIb(T13I) ▿

PubMed Central

Nawar, Hesham F.; Berenson, Charles S.; Hajishengallis, George; Takematsu, Hiromu; Mandell, Lorrie; Clare, Ragina L.; Connell, Terry D.

2010-01-01

By use of a mouse mucosal immunization model, LT-IIb(T13I), a nontoxic mutant type II heat-labile enterotoxin, was shown to have potent mucosal and systemic adjuvant properties. In contrast to LT-IIb, which binds strongly to ganglioside receptors decorated with either N-acetylneuraminic acid (NeuAc) or N-glycolylneuraminic acid (NeuGc), LT-IIb(T13I) binds NeuAc gangliosides much less well. Rather, LT-IIb(T13I) binds preferentially to NeuGc gangliosides. To determine if the adjuvant properties of LT-IIb(T13I) are altered in the absence of NeuGc ganglioside receptors, experiments were conducted using a Cmah-null mouse line which is deficient in the synthesis of NeuGc gangliosides. Several immunomodulatory properties of LT-IIb(T13I) were shown to be dependent on NeuGc gangliosides. LT-IIb(T13I) had reduced binding activity for NeuGc-deficient B cells and macrophages; binding to NeuGc-deficient T cells and dendritic cells (DC) was essentially undetectable. Treatment of Cmah-null macrophages with LT-IIb(T13I), however, upregulated the transcription of interleukin-4 (IL-4), IL-6, IL-17, and gamma interferon (IFN-γ), four cytokines important for promoting immune responses. The production of mucosal IgA and serum IgG against an immunizing antigen was augmented in NeuGc-deficient mice administered LT-IIb(T13I) as a mucosal adjuvant. Notably, NeuGc gangliosides are not expressed in humans. Still, treatment of human monocytes with LT-IIb(T13I) induced the secretion of IL-6, an inflammatory cytokine that mediates differential control of leukocyte activation. These results suggested that NeuAc gangliosides are sufficient to mediate the immunomodulatory properties of LT-IIb(T13I) in mice and in human cells. The nontoxic mutant enterotoxin LT-IIb(T13I), therefore, is potentially a new and safe human mucosal adjuvant. PMID:20392887

Recombinant expression of in silico identified Bcell epitope of epsilon toxin of Clostridium perfringens in translational fusion with a carrier protein.

PubMed

Kaushik, Himani; Deshmukh, Sachin; Mathur, Deepika Dayal; Tiwari, Archana; Garg, Lalit C

2013-01-01

Epsilon toxin secreted by Clostridium perfringens types B and D has been directly implicated as the causative agent of fatal enterotoxemia in domestic animals. The aim of the present study is to use in silico approach for identification of B-cell epitope(s) of epsilon toxin, and its expression in fusion with a carrier protein to analyze its potential as vaccine candidate(s). Using different computational analyses and bioinformatics tools, a number of antigenic determinant regions of epsilon toxin were identified. One of the B cell epitopes of epsilon toxin comprising the region (amino acids 40-62) was identified as a promising antigenic determinant. This Etx epitope (Etx40-62) was cloned and expressed as a translational fusion with B-subunit of heat labile enterotoxin (LTB) of E. coli in a secretory expression system. Similar to the native LTB, the recombinant fusion protein retained the ability to pentamerize and bind to GM1 ganglioside receptor of LTB. The rLTB.Etx40-62 could be detected both with anti-Etx and anti-LTB antisera. The rLTB.Etx40-62 fusion protein thus can be evaluated as a potential vaccine candidate against C. perfringens. aa - amino acid(s), Etx - epsilon toxin of Clostridium perfringens, LTB - B-subunit of heat labile enterotoxin of E. coli.

Outbreaks of cholera-like diarrhoea caused by enterotoxigenic Escherichia coli in the Brazilian Amazon Rainforest.

PubMed

Vicente, Ana C P; Teixeira, Luiz F M; Iniguez-Rojas, L; Luna, M G; Silva, L; Andrade, J R C; Guth, B E C

2005-09-01

The relationship between enteropathogens and severe diarrhoea in the Brazilian Amazon is poorly understood. In 1998, outbreaks of acute diarrhoea clinically diagnosed as cholera occurred in two small villages localized far from the main cholera route in the Brazilian rainforest. PCR was performed on some enteropathogens and heat-labile (LT) and/or heat-stable (STh) toxin genes, the virulence determinants of enterotoxigenic Escherichia coli (ETEC), were detected. Further characterization of ETEC isolates revealed the presence of two clones, one from each outbreak. One presenting serotype O167:H5 harboured LT-I and STh toxin genes and expressed the CS5CS6 colonization factor. The other, a non-typeable serotype, was positive for the LT-I gene and expressed the CS7 colonization factor. The current study demonstrates the importance of molecular diagnosis in regions such as the Amazon basin, where the enormous distances and local support conditions make standard laboratory diagnosis difficult. Here we also show that the mis-identified cholera cases were in fact associated with ETEC strains. This is the first report of ETEC, molecularly characterized as the aetiological agent of severe diarrhoea in children and adults in the Brazilian Amazon Rainforest.

Mood lability and psychopathology in youth.

PubMed

Stringaris, A; Goodman, R

2009-08-01

Mood lability is a concept widely used. However, data on its prevalence and morbid associations are scarce. We sought to establish the occurrence and importance of mood lability in a large community sample of children and adolescents by testing a priori hypotheses. Cross-sectional data were taken from a national mental health survey including 5326 subjects aged 8-19 years in the UK. The outcomes were prevalence and characteristics of mood lability and its associations with psychopathology and overall impairment. Mood lability occurred in more than 5% of the population of children and adolescents, both by parent and self-report. Mood lability was strongly associated with a wide range of psychopathology and was linked to significant impairment even in the absence of psychiatric disorders. Mood lability was particularly strongly associated with co-morbidity between internalizing and externalizing disorders, even when adjusting for the association with individual disorders. The pattern of results did not change after excluding youth with bipolar disorder or with episodes of elated mood. Clinically significant mood lability is relatively common in the community. Our findings indicate that mood lability is not a mere consequence of other psychopathology in that it is associated with significant impairment even in the absence of psychiatric diagnoses. Moreover, the pattern of association of mood lability with co-morbidity suggests that it could be a risk factor shared by both internalizing and externalizing disorders. Our data point to the need for greater awareness of mood lability and its implications for treatment.

Labile and Non-labile Soil Carbon Fractions Equally Contributed to Carbon Changes under Long-term Fertilization

NASA Astrophysics Data System (ADS)

Liang, F.; Li, J.; Xu, M.; Huang, S.

2017-12-01

Soil organic carbon (SOC) storages are altered under long-term fertilization in croplands, it however remains unclear how fast- to slow-cycling SOC fractions each respond to fertilization practices. Based on five two-decade Chinese long-term fertilization experiments (GZL: Gongzhuling; ZZ: Zhengzhou; CQ: Chongqing; JX: Jinxian; QY: Qiyang) under three fertilization treatments (CK: cropping with no fertilizer input; NPK: chemical nitrogen, phosphorus and potassium fertilizers; and NPKM: NPK with manure input), we quantified very labile, labile, non-labile and total SOC stocks at 0-20cm soil depth. Results showed that SOC stocks varied among sites (GZL, JX, CQ > ZZ, QY) and generally increased with fertilizations (CK-1 at ZZ, GZL, QY, CQ and JX, respectively. The corresponding changes of the sum of very labile and labile SOC fractions were 2.6, 2.0, 1.8, 0.8 and -0.5 Mg ha-1 at ZZ, QY, GZL, CQ and JX, respectively. Also, NPKM increased total SOC stock by 18.3, 16.2, 14.4, 10.5, and 6.5 Mg ha-1 at QY, GZL, ZZ, CQ and JX, respectively. The corresponding changes of the sum of very labile and labile SOC fractions were 8.6, 6.8, 6.6, 3.2 and -1.6 Mg ha-1 at QY, GZL, ZZ, CQ and JX, respectively. These results suggested that about half or more than half SOC stock accretions under fertilization were induced by increase in non-labile SOC fractions. It thus informs the importance of non-labile SOC fractions in contributing to soil C sequestration under long-term fertilizations in Chinese croplands. Future research should improve our mechanistic understanding of biogeochemical transformation of non-labile organic C in soils.

The ζ toxin induces a set of protective responses and dormancy.

PubMed

Lioy, Virginia S; Machon, Cristina; Tabone, Mariangela; Gonzalez-Pastor, José E; Daugelavicius, Rimantas; Ayora, Silvia; Alonso, Juan C

2012-01-01

The ζε module consists of a labile antitoxin protein, ε, which in dimer form (ε(2)) interferes with the action of the long-living monomeric ζ phosphotransferase toxin through protein complex formation. Toxin ζ, which inhibits cell wall biosynthesis and may be bactericide in nature, at or near physiological concentrations induces reversible cessation of Bacillus subtilis proliferation (protective dormancy) by targeting essential metabolic functions followed by propidium iodide (PI) staining in a fraction (20-30%) of the population and selects a subpopulation of cells that exhibit non-inheritable tolerance (1-5×10(-5)). Early after induction ζ toxin alters the expression of ∼78 genes, with the up-regulation of relA among them. RelA contributes to enforce toxin-induced dormancy. At later times, free active ζ decreases synthesis of macromolecules and releases intracellular K(+). We propose that ζ toxin induces reversible protective dormancy and permeation to PI, and expression of ε(2) antitoxin reverses these effects. At later times, toxin expression is followed by death of a small fraction (∼10%) of PI stained cells that exited earlier or did not enter into the dormant state. Recovery from stress leads to de novo synthesis of ε(2) antitoxin, which blocks ATP binding by ζ toxin, thereby inhibiting its phosphotransferase activity.

Heterologous Expression of Toxins from Bacterial Toxin-Antitoxin Systems in Eukaryotic Cells: Strategies and Applications

PubMed Central

Yeo, Chew Chieng; Abu Bakar, Fauziah; Chan, Wai Ting; Espinosa, Manuel; Harikrishna, Jennifer Ann

2016-01-01

Toxin-antitoxin (TA) systems are found in nearly all prokaryotic genomes and usually consist of a pair of co-transcribed genes, one of which encodes a stable toxin and the other, its cognate labile antitoxin. Certain environmental and physiological cues trigger the degradation of the antitoxin, causing activation of the toxin, leading either to the death or stasis of the host cell. TA systems have a variety of functions in the bacterial cell, including acting as mediators of programmed cell death, the induction of a dormant state known as persistence and the stable maintenance of plasmids and other mobile genetic elements. Some bacterial TA systems are functional when expressed in eukaryotic cells and this has led to several innovative applications, which are the subject of this review. Here, we look at how bacterial TA systems have been utilized for the genetic manipulation of yeasts and other eukaryotes, for the containment of genetically modified organisms, and for the engineering of high expression eukaryotic cell lines. We also examine how TA systems have been adopted as an important tool in developmental biology research for the ablation of specific cells and the potential for utility of TA systems in antiviral and anticancer gene therapies. PMID:26907343

The ζ Toxin Induces a Set of Protective Responses and Dormancy

PubMed Central

Tabone, Mariangela; Gonzalez-Pastor, José E.; Daugelavicius, Rimantas; Ayora, Silvia; Alonso, Juan C.

2012-01-01

The ζε module consists of a labile antitoxin protein, ε, which in dimer form (ε2) interferes with the action of the long-living monomeric ζ phosphotransferase toxin through protein complex formation. Toxin ζ, which inhibits cell wall biosynthesis and may be bactericide in nature, at or near physiological concentrations induces reversible cessation of Bacillus subtilis proliferation (protective dormancy) by targeting essential metabolic functions followed by propidium iodide (PI) staining in a fraction (20–30%) of the population and selects a subpopulation of cells that exhibit non-inheritable tolerance (1–5×10−5). Early after induction ζ toxin alters the expression of ∼78 genes, with the up-regulation of relA among them. RelA contributes to enforce toxin-induced dormancy. At later times, free active ζ decreases synthesis of macromolecules and releases intracellular K+. We propose that ζ toxin induces reversible protective dormancy and permeation to PI, and expression of ε2 antitoxin reverses these effects. At later times, toxin expression is followed by death of a small fraction (∼10%) of PI stained cells that exited earlier or did not enter into the dormant state. Recovery from stress leads to de novo synthesis of ε2 antitoxin, which blocks ATP binding by ζ toxin, thereby inhibiting its phosphotransferase activity. PMID:22295078

[Pathogenic activity modulation of Escherichia coli TL+ toxin with an isolated protein of Giardia intestinalis and a synthetic peptide].

PubMed

Jiménez-Cardoso, E; Eligio-García, L; Jiménez-Cardoso, J M; Angeles-Anguiano, E; Tobilla-Mercado, J M; Castañeda, G

2001-01-01

It is know that a protein from Giardia intestinalis works as a substrate for V. cholerae and Escherichia coli. The toxic activity of both activates protein G form intestinal mucosa with a pathogenic activity results. In the present study, the pathogenic activity of subunit A of Vibrio cholerae toxin (ADP-ribosyltranferase) using isolated fragments from: Giardia intestinalis and a synthetic peptide were used as modulators in vivo. Adult Neo Zealand males rabbits with ileal loop were prepared and different mixtures of heat labile enterotoxin obtained from Escherichia coli H10407 and ARF protein isolated by electrofocusing from Giardia intestinalis Portland I were inoculated in the loops. The toxin activity was evaluated by luminal liquid secretion and cyclic AMP concentration in tissues (each loop). ADP ribosyltranferase activity was modulated, due to a decreased of luminal secretion and cAMP in tissues. Such results were seen when synthetic peptide and subunit A from Vibrio cholerae were used. The ADP ribosyltranferase activity of heat labile Escherichia coli and Vibrio cholerae toxins were modified by in vitro and in vivo interaction with ARF protein, which modified pathogenic effect over rabbits intestinal epithelium.

Properties of dermonecrotic toxin prepared from sonic extracts Bordetella bronchiseptica.

PubMed

Kume, K; Nakai, T; Samejima, Y; Sugimoto, C

1986-05-01

A toxin with dermonecrotic activity (DNT) was purified from sonic extracts of Bordetella bronchiseptica L3 of pig origin at phase I by chromatographic and electrophoretic methods. The purification procedure was one developed for obtaining the Pasteurella multocida DNT from sonic extracts with some modifications. Dermonecrotizing activity of B. bronchiseptica-purified DNT was increased by 600-fold compared with that of the crude extract, and the average yield was about 3%. The toxin was homogeneous, as determined by Ouchterlony double immunodiffusion, crossed immunoelectrophoresis, and disk isoelectric focusing in polyacrylamide gels. The toxin gave a single band on polyacrylamide disk gel electrophoresis (PAGE) and sodium dodecyl sulfate-SDS PAGE. The molecular weight of the toxin was ca. 190,000 +/- 5,000, as determined by SDS-PAGE. The isoelectric point of the toxin was ca. 6.5 to 6.6. The minimal necrotizing dose of the toxin for guinea pigs was about 2 ng of protein per 0.1 ml, the 50% lethal dose per mouse was about 0.3 micrograms, and the minimal cytotoxic dose for embryonic bovine lung cells was about 2 ng/ml. The toxin was heat labile and sensitive to inactivation by trypsin, Formalin, and glutaraldehyde. The mildly trypsinized B. bronchiseptica DNT preparation dissociated into two polypeptide chains, with molecular weights of ca. 75,000 +/- 4,000 (fragment 1) and ca. 118,000 +/- 5,000 (fragment 2), after treatment with dithiothreitol-SDS or urea. Upon removal of dithiothreitol and urea from the dissociated DNT preparation, the fragments reassociated, and the DNT that was formed was indistinguishable from the native toxin.

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) (μmol C mol photons-1) at 330 nm. The corresponding values for BLPs supporting bacterial respiration ranged from 57 to 1204 (mean 320) (μmol 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.

HaLT2- an enhanced lumber grading trainer

Treesearch

Powsiri Klinkhachorn; Charles Gatchell; Charles McMillin; Ravi Kothari; Dennis Yost

1992-01-01

This paper reports on HaLT2, an improved version of HaLT (Hardwood Lumber Traning Program)- a computer program that provides training in lumber grading. The newly added enhancements In HaLT2 will provide training for both novice and experienced hardwood lumber graders in accordance with National Hardwood Lumber Assodation (NHLA) rules. HaLT2 is more accurate, easier to...

Metal Complexes and Free Radical Toxins Produced by Pfiesteria piscicida

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moeller,P.; Beauchesne, K.; Huncik, K.

2007-01-01

Metal-containing organic toxins produced by Pfiesteria piscicida were characterized, for the first time, by corroborating data obtained from five distinct instrumental methods: nuclear magnetic resonance spectroscopy (NMR), inductively coupled plasma mass spectrometry (ICP-MS), liquid chromatography particle beam glow discharge mass spectrometry (LC/PB-GDMS), electron paramagnetic resonance spectroscopy (EPR), and X-ray absorption spectroscopy (XAS). The high toxicity of the metal-containing toxins is due to metal-mediated free radical production. This mode of activity explains the toxicity of Pfiesteria, as well as previously reported difficulty in observing the molecular target, due to the ephemeral nature of radical species. The toxins are highly labile inmore » purified form, maintaining activity for only 2-5 days before all activity is lost. The multiple toxin congeners in active extracts are also susceptible to decomposition in the presence of white light, pH variations, and prolonged heat. These findings represent the first formal isolation and characterization of a radical forming toxic organic-ligated metal complex isolated from estuarine/marine dinoflagellates. These findings add to an increased understanding regarding the active role of metals interacting with biological systems in the estuarine environment, as well as their links and implications to human health.« less

Metal Complexes And Free Radical Toxins Produced By Pfiesteria Piscicida

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moeller, P.D.R.; Beauchesne, K.R.; Huncik, K.M.

2009-06-03

Metal-containing organic toxins produced by Pfiesteria piscicida were characterized, for the first time, by corroborating data obtained from five distinct instrumental methods: nuclear magnetic resonance spectroscopy (NMR), inductively coupled plasma mass spectrometry (ICPMS), liquid chromatography particle beam glow discharge mass spectrometry (LC/PB-GDMS), electron paramagnetic resonance spectroscopy (EPR), and X-ray absorption spectroscopy (XAS). The high toxicity of the metal-containing toxins is due to metal-mediated free radical production. This mode of activity explains the toxicity of Pfiesteria, as well as previously reported difficulty in observing the molecular target, due to the ephemeral nature of radical species. The toxins are highly labile inmore » purified form, maintaining activity for only 2-5 days before all activity is lost. The multiple toxin congeners in active extracts are also susceptible to decomposition in the presence of white light, pH variations, and prolonged heat. These findings represent the first formal isolation and characterization of a radical forming toxic organic-ligated metal complex isolated from estuarine/marine dinoflagellates. These findings add to an increased understanding regarding the active role of metals interacting with biological systems in the estuarine environment, as well as their links and implications to human health.« less

Lymphotoxin beta receptor (Lt betaR): dual roles in demyelination and remyelination and successful therapeutic intervention using Lt betaR-Ig protein.

PubMed

Plant, Sheila R; Iocca, Heather A; Wang, Ying; Thrash, J Cameron; O'Connor, Brian P; Arnett, Heather A; Fu, Yang-Xin; Carson, Monica J; Ting, Jenny P-Y

2007-07-11

Inflammation mediated by macrophages is increasingly found to play a central role in diseases and disorders that affect a myriad of organs, prominent among these are diseases of the CNS. The neurotoxicant-induced, cuprizone model of demyelination is ideally suited for the analysis of inflammatory events. Demyelination on exposure to cuprizone is accompanied by predictable microglial activation and astrogliosis, and, after cuprizone withdrawal, this activation reproducibly diminishes during remyelination. This study demonstrates enhanced expression of lymphotoxin beta receptor (Lt betaR) during the demyelination phase of this model, and Lt betaR is found in areas enriched with microglial and astroglial cells. Deletion of the Lt betaR gene (Lt betaR-/-) resulted in a significant delay in demyelination but also a slight delay in remyelination. Inhibition of Lt betaR signaling by an Lt betaR-Ig fusion decoy protein successfully delayed demyelination in wild-type mice. Unexpectedly, this Lt betaR-Ig decoy protein dramatically accelerated the rate of remyelination, even after the maximal pathological disease state had been reached. This strongly indicates the beneficial role of Lt betaR-Ig in the delay of demyelination and the acceleration of remyelination. The discrepancy between remyelination rates in these systems could be attributed to developmental abnormalities in the immune systems of Lt betaR-/- mice. These findings bode well for the use of an inhibitory Lt betaR-Ig as a candidate biological therapy in demyelinating disorders, because it is beneficial during both demyelination and remyelination.

Contractile actin cables induced by Bacillus anthracis lethal toxin depend on the histone acetylation machinery.

PubMed

Rolando, Monica; Stefani, Caroline; Doye, Anne; Acosta, Maria I; Visvikis, Orane; Yevick, Hannah G; Buchrieser, Carmen; Mettouchi, Amel; Bassereau, Patricia; Lemichez, Emmanuel

2015-10-01

It remains a challenge to decode the molecular basis of the long-term actin cytoskeleton rearrangements that are governed by the reprogramming of gene expression. Bacillus anthracis lethal toxin (LT) inhibits mitogen-activated protein kinase (MAPK) signaling, thereby modulating gene expression, with major consequences for actin cytoskeleton organization and the loss of endothelial barrier function. Using a laser ablation approach, we characterized the contractile and tensile mechanical properties of LT-induced stress fibers. These actin cables resist pulling forces that are transmitted at cell-matrix interfaces and at cell-cell discontinuous adherens junctions. We report that treating the cells with trichostatin A (TSA), a broad range inhibitor of histone deacetylases (HDACs), or with MS-275, which targets HDAC1, 2 and 3, induces stress fibers. LT decreased the cellular levels of HDAC1, 2 and 3 and reduced the global HDAC activity in the nucleus. Both the LT and TSA treatments induced Rnd3 expression, which is required for the LT-mediated induction of actin stress fibers. Furthermore, we reveal that treating the LT-intoxicated cells with garcinol, an inhibitor of histone acetyl-transferases (HATs), disrupts the stress fibers and limits the monolayer barrier dysfunctions. These data demonstrate the importance of modulating the flux of protein acetylation in order to control actin cytoskeleton organization and the endothelial cell monolayer barrier. © 2015 Wiley Periodicals, Inc.

HyBoLT Flight Experiment

NASA Technical Reports Server (NTRS)

Chen, Fang-Jeng (Frank); Berry, Scott A.

2010-01-01

HyBoLT was a Hypersonic Boundary Layer Transition flight experiment funded by the Hypersonics Project of the Fundamental Aeronautics Program in NASA's Aeronautics Research Mission Directorate. The HyBoLT test article mounted on the top of the ALV X-1 rocket was launched from Virginia's Wallops Island on August 22, 2008. Unfortunately a problem in the rocket's flight control system caused the vehicle to veer off the designed flight course. Launch officials activated a self-destruct mechanism in the rocket's nose cone after 20 seconds into flight. This report is a closeout document about the HyBoLT flight experiment. Details are provided of the objectives and approach associated with this experimental program as well as the 20 seconds flight data acquired before the vehicle was destroyed.

Lethal factor antibodies contribute to lethal toxin neutralization in recipients of anthrax vaccine precipitated.

PubMed

Dumas, Eric K; Garman, Lori; Cuthbertson, Hannah; Charlton, Sue; Hallis, Bassam; Engler, Renata J M; Choudhari, Shyamal; Picking, William D; James, Judith A; Farris, A Darise

2017-06-08

A major difference between two currently licensed anthrax vaccines is presence (United Kingdom Anthrax Vaccine Precipitated, AVP) or absence (United States Anthrax Vaccine Adsorbed, AVA) of quantifiable amounts of the Lethal Toxin (LT) component Lethal Factor (LF). The primary immunogen in both vaccine formulations is Protective Antigen (PA), and LT-neutralizing antibodies directed to PA are an accepted correlate of vaccine efficacy; however, vaccination studies in animal models have demonstrated that LF antibodies can be protective. In this report we compared humoral immune responses in cohorts of AVP (n=39) and AVA recipients (n=78) matched 1:2 for number of vaccinations and time post-vaccination, and evaluated whether the LF response contributes to LT neutralization in human recipients of AVP. PA response rates (≥95%) and PA IgG concentrations were similar in both groups; however, AVP recipients exhibited higher LT neutralization ED 50 values (AVP: 1464.0±214.7, AVA: 544.9±83.2, p<0.0001) and had higher rates of LF IgG positivity (95%) compared to matched AVA vaccinees (1%). Multiple regression analysis revealed that LF IgG makes an independent and additive contribution to the LT neutralization response in the AVP group. Affinity purified LF antibodies from two independent AVP recipients neutralized LT and bound to LF Domain 1, confirming contribution of LF antibodies to LT neutralization. This study documents the benefit of including an LF component to PA-based anthrax vaccines. Copyright © 2017 Elsevier Ltd. All rights reserved.

Randomised, double-blind, safety and efficacy of a killed oral vaccine for enterotoxigenic E. Coli diarrhoea of travellers to Guatemala and Mexico.

PubMed

Sack, David A; Shimko, Janet; Torres, Olga; Bourgeois, August L; Francia, Domingo Sanchez; Gustafsson, Björn; Kärnell, Anders; Nyquist, Iréne; Svennerholm, Ann-Mari

2007-05-30

We tested the efficacy of a killed oral vaccine for enterotoxigenic Escherichia coli (ETEC) diarrhoea to determine if two doses of vaccine with colonization factor antigens (CF) and cholera B subunit would protect against ETEC diarrhoea of travellers. Six hundred seventy-two healthy travellers going to Mexico or Guatemala were studied in a prospective, randomised, placebo-controlled trial. The primary outcome was a vaccine preventable outcome (VPO), defined as an episode of ETEC diarrhoea with an ETEC organism producing heat labile toxin (LT) or CF homologous with the vaccine, without other known causes. The vaccine was safe and stimulated anti-heat labile toxin antibodies. There was a significant decrease in more severe VPO episodes (PE=77%, p=0.039) as defined by symptoms that interfered with daily activities or more than five loose stools in a day, although the total number of VPO events did not differ significantly in the vaccine and placebo groups. We conclude that the new oral ETEC vaccine reduces the rate of more severe episodes of traveller's diarrhoea (TD) due to VPO-ETEC, but it did not reduce the overall rate of ETEC diarrhoea or of travellers' diarrhoea due to other causes.

Studies on Pongamia pinnata (L.) Pierre leaves: understanding the mechanism(s) of action in infectious diarrhea*

PubMed Central

Brijesh, S.; Daswani, P.G.; Tetali, P.; Rojatkar, S.R.; Antia, N.H.; Birdi, T.J.

2006-01-01

While data are available on the effect of medicinal plants on intestinal motility and their antibacterial action, there is a paucity of information on their mode of action on various aspects of diarrheal pathogenicity, namely colonization to intestinal epithelial cells and production/action of enterotoxins. Crude decoction of dried leaves of Pongamia pinnata was evaluated for its antimicrobial (antibacterial, antigiardial and antirotaviral) effect; and its effect on production and action of enterotoxins (cholera toxin, CT; Escherichia coli labile toxin, LT; and E. coli stable toxin, ST); and adherence of enteropathogenic E. coli and invasion of enteroinvasive E. coli and Shigella flexneri to epithelial cells. The decoction had no antibacterial, antigiardial and antirotaviral activity, but reduced production of CT and bacterial invasion to epithelial cells. The observed results indicated that the crude decoction of P. pinnata has selective antidiarrheal action with efficacy against cholera and enteroinvasive bacterial strains causing bloody diarrheal episodes. PMID:16845722

Light availability affects sex lability in a gynodioecious plant.

PubMed

Varga, Sandra; Kytöviita, Minna-Maarit

2016-11-01

Sex lability (i.e., gender diphasy) in plants is classically linked to the larger resource needs associated with the female sexual function (i.e., seed production) compared to the male function (i.e., pollen production). Sex lability in response to the environment is extensively documented in dioecious species, but has been largely overlooked in gynodioecious plants. Here, we tested whether environmental conditions induce sex lability in the gynodioecious Geranium sylvaticum. We conducted a transplantation experiment in the field where plants with different sex expression were reciprocally transplanted between high light and low light habitats. We measured plants' reproductive output and sex expression over four years. Our results show that sex expression was labile over the study period. The light level at the destination habitat had a significant effect on sexual expression and reproductive output, because plants decreased their reproductive output when transplanted to the low light habitat. Transplantation origin did not affect any parameter measured. This study shows that sex expression in Geranium sylvaticum is labile and related to light availability. Sexually labile plants did not produce more seeds or pollen, and thus, there was no apparent fitness gain in sexually labile individuals. Sex lability in gynodioecious plants may be more common than previously believed because detection of sex lability necessitates data on the same individuals over time, which is rare in sexually dimorphic herbaceous plants. © 2016 Botanical Society of America.

Anthrax Lethal Toxin Impairs Innate Immune Functions of Alveolar Macrophages and Facilitates Bacillus anthracis Survival

PubMed Central

Ribot, Wilson J.; Panchal, Rekha G.; Brittingham, Katherine C.; Ruthel, Gordon; Kenny, Tara A.; Lane, Douglas; Curry, Bob; Hoover, Timothy A.; Friedlander, Arthur M.; Bavari, Sina

2006-01-01

Alveolar macrophages (AM) are very important for pulmonary innate immune responses against invading inhaled pathogens because they directly kill the organisms and initiate a cascade of innate and adaptive immune responses. Although several factors contribute to inhalational anthrax, we hypothesized that unimpeded infection of Bacillus anthracis is directly linked to disabling the innate immune functions contributed by AM. Here, we investigated the effects of lethal toxin (LT), one of the binary complex virulence factors produced by B. anthracis, on freshly isolated nonhuman primate AM. Exposure of AM to doses of LT that killed susceptible macrophages had no effect on the viability of AM, despite complete MEK1 cleavage. Intoxicated AM remained fully capable of B. anthracis spore phagocytosis. However, pretreatment of AM with LT resulted in a significant decrease in the clearance of both the Sterne strain and the fully virulent Ames strain of B. anthracis, which may have been a result of impaired AM secretion of proinflammatory cytokines. Our data imply that cytolysis does not correlate with MEK1 cleavage, and this is the first report of LT-mediated impairment of nonhuman primate AM bactericidal activity against B. anthracis. PMID:16926394

Enteroaggregative Escherichia coli strains secrete a heat-labile toxin antigenically related to E. coli hemolysin.

PubMed Central

Baldwin, T J; Knutton, S; Sellers, L; Hernandez, H A; Aitken, A; Williams, P H

1992-01-01

A protein toxin of approximately 120,000 Da secreted by nonhemolytic enteroaggregative Escherichia coli strains cross-reacted in Western blots (immunoblots) with antibodies raised against the C-terminal region of E. coli hemolysin. Treatment of HEp-2 cells with enteroaggregative E. coli or culture supernatants caused elevation of intracellular calcium and stimulated calcium-dependent protein phosphorylation. Images PMID:1563799

Soluble P-selectin rescues mice from anthrax lethal toxin-induced mortality through PSGL-1 pathway-mediated correction of hemostasis.

PubMed

Sun, Der-Shan; Chang, Yao-Wen; Kau, Jyh-Hwa; Huang, Hsin-Hsien; Ho, Pei-Hsun; Tzeng, Yin-Jeh; Chang, Hsin-Hou

2017-10-03

As one of the virulence factors of Bacillus anthracis, lethal toxin (LT) induces various pathogenic responses including the suppression of the coagulation system. In this study, we observed that LT markedly increased the circulating soluble P-selectin (sP-sel) levels and microparticle (MP) count in wild-type but not P-selectin (P-sel, Selp -/- ) or P-sel ligand-1 (PSGL-1, Selplg -/- ) knockout mice. Because sP-sel induces a hypercoagulable state through PSGL-1 pathway to generate tissue factor-positive MPs, we hypothesized that the increase in plasma sP-sel levels can be a self-rescue response in hosts against the LT-mediated suppression of the coagulation system. In agreement with our hypothesis, our results indicated that compared with wild-type mice, Selp -/- and Selplg -/- mice were more sensitive to LT. In addition, the recombinant sP-sel treatment markedly ameliorated LT-mediated pathogenesis and reduced mortality. As a result, elicitation of circulating sP-sel is potentially a self-rescue response, which is beneficial to host recovery from an LT-induced hypocoagulation state. These results suggest that the administration of sP-sel is likely to be useful in the development of a new strategy to treat anthrax.

Effect of water activity and pH on growth and toxin production by Clostridium botulinum type G.

PubMed Central

Briozzo, J; de Lagarde, E A; Chirife, J; Parada, J L

1986-01-01

The combined effect of water activity (aw) and pH on growth and toxin production by Clostridium botulinum type G strain 89 was investigated. The minimum aw at which growth and toxin formation occurred was 0.965, for media in which the pH was adjusted with either sodium chloride or sucrose. The minimum pH (at the optimum aw) for growth and toxin production of C. botulinum type G was found to be 5.6. Optimum conditions for toxin activation were a trypsin concentration of 0.1%, a pH of the medium of 6.5, and an incubation for 45 min at 37 degrees C. These data did not show evidence of heat-labile spores, since a heat shock of 75 degrees C for 10 min did not significantly decrease the spore count of strain 89G in media at pH 7.0 or 5.6. It was frequently observed that cells grown at reduced aw or pH experienced severe morphological changes. PMID:3518631

A Systematic Review of Clinical Practice Guidelines' Recommendations on Levothyroxine Therapy Alone versus Combination Therapy (LT4 plus LT3) for Hypothyroidism.

PubMed

Kraut, Eyal; Farahani, Pendar

2015-12-04

Patients with hypothyroidism are increasingly enquiring about the benefit of using combination therapy of levothyroxine (LT4) and liothyronine (LT3) as a potential treatment for hypothyroidism. Combination therapy, however, remains controversial. The purpose of this study was to systematically review available hypothyroidism treatment recommendations from clinical practice guidelines from around the world to identify the consensus regarding combination therapy. Clinical practice guidelines were obtained from searches of PubMed, EMBASE, and MEDLINE, using several combinations of MeSH terms. The search was limited to clinical guidelines in English-language publications, published between January 1, 1990 and May 1, 2015. A quantitative approach was utilized for data synthesis. Thirteen guidelines were identified, including three regarding pregnancy, two regarding pediatric populations and eight regarding adult populations. There were six guidelines from North America, four guidelines from Europe and three guidelines from South America. Twelve of the guidelines were published after 2010. Nine guidelines addressed combination therapy of LT4 plus LT3, and all nine concluded that LT4 therapy alone is the standard of care, with insufficient evidence to recommend widespread combination therapy. Only the 2012 ETA Guidelines and the 2015 BTA Guidelines concluded that combination therapy could be used, although only in certain circumstances and as an experimental treatment. This systematic review illustrates that clinical practice guidelines worldwide do not recommend and do not support routine use of combination LT4 and LT3 therapy to treat hypothyroidism.

Effects of Long-Term Combination LT4 and LT3 Therapy for Improving Hypothyroidism and Overall Quality of Life.

PubMed

Tariq, Anam; Wert, Yijin; Cheriyath, Pramil; Joshi, Renu

2018-06-01

Hypothyroidism results in decreased mood and neurocognition, weight gain, fatigue, and many other undesirable symptoms. The American Association of Clinical Endocrinologists, the American Thyroid Association (ATA), and The Endocrine Society recommend levothyroxine (LT4) monotherapy as the treatment for hypothyroidism; however, after years of monotherapy, some patients continue to experience impaired quality of life. Combination LT4 and synthetic liothyronine (LT3) therapy or the use of desiccated thyroid extract (DTE), has not been suggested for this indication based on short-duration studies with no significant benefits. Our first observational study examined the role of combination therapy for 6 years in improving quality of life in a subset of a hypothyroid population without adverse effects and cardiac mortality. An observational retrospective study examining patients prescribed thyroid replacements with serum triiodothyronine (FT3), LT4 with LT3 (synthetic therapy) or DTE (natural therapy), compared with LT4 alone in the United States from 2010 to 2016. Thyroid-stimulating hormone (TSH), serum thyroxine (FT4), and FT3 levels were documented for each patient in addition to any admissions of myxedema coma, thyrotoxicosis, or cardiovascular complications, such as arrhythmias, atrial fibrillation, and mortality. At the conclusion of the study, a cross-sectional interview assessed quality of life for each combination therapy through the Medical Outcomes Study Short Form-20 questionnaire. Compared with patients taking only LT4, 89.47% using synthetic therapy had therapeutic TSH ( P < 0.05). Similarly, 96.49% using natural therapy had therapeutic TSH ( P < 0.05). Less than 5% of patients had supratherapeutic FT3. None of the patients who had abnormally low TSH or elevated FT3 or FT4 levels had hospitalizations for arrhythmias or thyrotoxicosis. On the Medical Outcomes Study Short Form-20 questionnaire, >92% answered feeling "excellent, very good, or good" when

An Enterotoxin-Like Binary Protein from Pseudomonas protegens with Potent Nematicidal Activity.

PubMed

Wei, Jun-Zhi; Siehl, Daniel L; Hou, Zhenglin; Rosen, Barbara; Oral, Jarred; Taylor, Christopher G; Wu, Gusui

2017-10-01

Soil microbes are a major food source for free-living soil nematodes. It is known that certain soil bacteria have evolved systems to combat predation. We identified the nematode-antagonistic Pseudomonas protegens strain 15G2 from screening of microbes. Through protein purification we identified a binary protein, designated Pp-ANP, which is responsible for the nematicidal activity. This binary protein inhibits Caenorhabditis elegans growth and development by arresting larvae at the L1 stage and killing older-staged worms. The two subunits, Pp-ANP1a and Pp-ANP2a, are active when reconstituted from separate expression in Escherichia coli The binary toxin also shows strong nematicidal activity against three other free-living nematodes ( Pristionchus pacificus , Panagrellus redivivus , and Acrobeloides sp.), but we did not find any activity against insects and fungi under test conditions, indicating specificity for nematodes. Pp-ANP1a has no significant identity to any known proteins, while Pp-ANP2a shows ∼30% identity to E. coli heat-labile enterotoxin (LT) subunit A and cholera toxin (CT) subunit A. Protein modeling indicates that Pp-ANP2a is structurally similar to CT/LT and likely acts as an ADP-ribosyltransferase. Despite the similarity, Pp-ANP shows several characteristics distinct from CT/LT toxins. Our results indicate that Pp-ANP is a new enterotoxin-like binary toxin with potent and specific activity to nematodes. The potency and specificity of Pp-ANP suggest applications in controlling parasitic nematodes and open an avenue for further research on its mechanism of action and role in bacterium-nematode interaction. IMPORTANCE This study reports the discovery of a new enterotoxin-like binary protein, Pp-ANP, from a Pseudomonas protegens strain. Pp-ANP shows strong nematicidal activity against Caenorhabditis elegans larvae and older-staged worms. It also shows strong activity on other free-living nematodes ( Pristionchus pacificus , Panagrellus redivivus , and

Emotional Lability and Affective Synchrony in Borderline Personality Disorder

PubMed Central

Schoenleber, Michelle; Berghoff, Christopher R.; Tull, Matthew T.; DiLillo, David; Messman-Moore, Terri; Gratz, Kim L.

2015-01-01

Extant research on emotional lability in borderline personality disorder (BPD) has focused almost exclusively on lability of individual emotions or emotion types, with limited research considering how different types of emotions shift together over time. Thus, this study examined the temporal dynamics of emotion in BPD at the level of both individual emotions (i.e., self-conscious emotions [SCE], anger, and anxiety) and mixed emotions (i.e., synchrony between emotions). One hundred forty-four women from the community completed a diagnostic interview and laboratory study involving five emotion induction tasks (each of which was preceded and followed by a 5-min resting period or neutral task). State ratings of SCE, anger, and anxiety were provided at 14 time points (before and after each laboratory task and resting period). Hierarchical linear modeling results indicate that women with BPD reported greater mean levels of SCE and Anxiety (but not Anger), and greater lability of Anxiety. Women with BPD also exhibited greater variability in lability of all three emotions (suggestive of within-group differences in the relevance of lability to BPD). Results also revealed synchrony (i.e., positive relations) between each possible pair of emotions, regardless of BPD status. Follow-up regression analyses suggest the importance of accounting for lability when examining the role of synchrony in BPD, as the relation of SCE-Anger synchrony to BPD symptom severity was moderated by Anger and SCE lability. Specifically, synchronous changes in SCE and Anger were associated with greater BPD symptom severity when large shifts in SCE were paired with minor shifts in Anger. PMID:27362623

Comparative analysis of antimicrobial resistance in enterotoxigenic Escherichia coli isolates from two paediatric cohort studies in Lima, Peru

PubMed Central

Medina, Anicia M.; Rivera, Fulton P.; Pons, Maria J.; Riveros, Maribel; Gomes, Cláudia; Bernal, María; Meza, Rina; Maves, Ryan C.; Huicho, Luis; Chea-Woo, Elsa; Lanata, Claudio F.; Gil, Ana I.; Ochoa, Theresa J.; Ruiz, Joaquim

2015-01-01

Background Antibiotic resistance is increasing worldwide, being of special concern in low- and middle-income countries. The aim of this study was to determine the antimicrobial susceptibility and mechanisms of resistance in 205 enterotoxigenic Escherichia coli (ETEC) isolates from two cohort studies in children <24 months in Lima, Peru. Methods ETEC were identified by an in-house multiplex real-time PCR. Susceptibility to 13 antimicrobial agents was tested by disk diffusion; mechanisms of resistance were evaluated by PCR. Results ETEC isolates were resistant to ampicillin (64%), cotrimoxazole (52%), tetracycline (37%); 39% of the isolates were multidrug-resistant. Heat-stable toxin producing (ETEC-st) (48%) and heat-labile toxin producing ETEC (ETEC-lt) (40%) had higher rates of multidrug resistance than isolates producing both toxins (ETEC-lt-st) (21%), p<0.05. Only 10% of isolates were resistant to nalidixic acid and none to ciprofloxacin or cefotaxime. Ampicillin and sulfamethoxazole resistance were most often associated with blaTEM (69%) and sul2 genes (68%), respectively. Tetracycline resistance was associated with tet(A) (49%) and tet(B) (39%) genes. Azithromycin inhibitory diameters were ≤15 mm in 36% of isolates, with 5% of those presenting the mph(A) gene. Conclusions ETEC from Peruvian children are often resistant to older, inexpensive antibiotics, while remaining susceptible to ciprofloxacin, cephalosporins and furazolidone. Fluoroquinolones and azithromycin remain the drugs of choice for ETEC infections in Peru. However, further development of resistance should be closely monitored. PMID:26175267

Genotypic and Phenotypic Characterization of Enterotoxigenic Escherichia coli Strains Isolated from Peruvian Children ▿

PubMed Central

Rivera, F. P.; Ochoa, T. J.; Maves, R. C.; Bernal, M.; Medina, A. M.; Meza, R.; Barletta, F.; Mercado, E.; Ecker, L.; Gil, A. I.; Hall, E. R.; Huicho, L.; Lanata, C. F.

2010-01-01

Enterotoxigenic Escherichia coli (ETEC) is a major cause of childhood diarrhea. The present study sought to determine the prevalence and distribution of toxin types, colonization factors (CFs), and antimicrobial susceptibility of ETEC strains isolated from Peruvian children. We analyzed ETEC strains isolated from Peruvian children between 2 and 24 months of age in a passive surveillance study. Five E. coli colonies per patient were studied by multiplex real-time PCR to identify ETEC virulence factors. ETEC-associated toxins were confirmed using a GM1-based enzyme-linked immunosorbent assay. Confirmed strains were tested for CFs by dot blot assay using 21 monoclonal antibodies. We analyzed 1,129 samples from children with diarrhea and 744 control children and found ETEC in 5.3% and 4.3%, respectively. ETEC was more frequently isolated from children >12 months of age than from children <12 months of age (P < 0.001). Fifty-two percent of ETEC isolates from children with diarrhea and 72% of isolates from controls were heat-labile enterotoxin (LT) positive and heat-stable enterotoxin (ST) negative; 25% and 19%, respectively, were LT negative and ST positive; and 23% and 9%, respectively, were LT positive and ST positive. CFs were identified in 64% of diarrheal samples and 37% of control samples (P < 0.05). The most common CFs were CS6 (14% and 7%, respectively), CS12 (12% and 4%, respectively), and CS1 (9% and 4%, respectively). ST-producing ETEC strains caused more severe diarrhea than non-ST-producing ETEC strains. The strains were most frequently resistant to ampicillin (71%) and co-trimoxazole (61%). ETEC was thus found to be more prevalent in older infants. LT was the most common toxin type; 64% of strains had an identified CF. These data are relevant in estimating the burden of disease due to ETEC and the potential coverage of children in Peru by investigational vaccines. PMID:20631096

Efficacy of combined or single use of Lactobacillus crispatus LT116 and L. johnsonii LT171 on broiler performance.

PubMed

Taheri, H R; Moravej, H; Tabandeh, F; Zaghari, M; Shivazad, M

2010-10-01

1. The objective of this research was to investigate the efficacy of combined or single use of Lactobacillus crispatus LT116 and Lactobacillus johnsonii LT171 on broiler performance. 2. A total of 320 one-d-old male Ross broiler chicks were allocated in 4 experimental treatments for 6 weeks. The experimental treatments received a maize-soybean meal basal diet that was supplemented as follows: 'control', with no other additions; 'LJ', 1 × 10(6) CFU of L. johnsonii LT171; 'LC', 1 × 10(6) CFU of L. crispatus LT116; and 'LCJ', 0·5 × 10(6) CFU of L. johnsonii LT171 + 0·5 × 10(6) CFU of L. crispatus LT116/g of the diet. A suspension of sheep red blood cells (SRBC) was injected into the breast of 8 birds from each treatment on d 14 and 30, and the antibody titre was measured on d 20, 26, 36 and 42. 3. Body weight was improved when compared with control for broilers fed diets supplemented with LCJ. The feed conversion ratio (FCR) decreased in LC and LCJ groups compared with control. The number of coliforms in the ileum of LJ, LC and LCJ birds was lower than that from the control birds. However, only the LCJ treatment significantly decreased the number of coliforms in the caecum. The LCJ group had greater villus height in the duodenum than the LC group, and both LCJ and LC groups showed increased villus height in the duodenum and jejunum relative to the control. Antibody titre against SRBC was higher for the LCJ group than for the LJ and control groups in terms of secondary immune response (mean of 36 and 42 d). 4. This study showed, compared with the control, that the combination of Lactobacillus spp. could positively affect body weight, coliform numbers in the caecum and immune response.

Characterization of plasma labile heme in hemolytic conditions

PubMed Central

Gouveia, Zélia; Carlos, Ana R.; Yuan, Xiaojing; Aires-da-Silva, Frederico; Stocker, Roland; Maghzal, Ghassan J.; Leal, Sónia S.; Gomes, Cláudio M.; Todorovic, Smilja; Iranzo, Olga; Ramos, Susana; Santos, Ana C.; Hamza, Iqbal; Gonçalves, João; Soares, Miguel P.

2018-01-01

Extracellular hemoglobin, a byproduct of hemolysis, can release its prosthetic heme groups upon oxidation. This produces metabolically active heme that is exchangeable between acceptor proteins, macromolecules and low molecular weight ligands, termed here labile heme. As it accumulates in plasma labile heme acts in a pro-oxidant manner and regulates cellular metabolism while exerting pro-inflammatory and cytotoxic effects that foster the pathogenesis of hemolytic diseases. Here, we developed and characterized a panel of heme-specific single domain antibodies (sdAbs) that together with a cellular-based heme reporter assay, allow for quantification and characterization of labile heme in plasma during hemolytic conditions. Using these approaches, we demonstrate that when generated during hemolytic conditions labile heme is bound to plasma molecules with an affinity higher than 10−7 m and that 2–8% (∼ 2–5 μm) of the total amount of heme detected in plasma can be internalized by bystander cells, termed here bioavailable heme. Acute, but not chronic, hemolysis is associated with transient reduction of plasma heme-binding capacity, that is, the ability of plasma molecules to bind labile heme with an affinity higher than 10−7 m. The heme-specific sdAbs neutralize the pro-oxidant activity of soluble heme in vitro, suggesting that these maybe used to counter the pathologic effects of labile heme during hemolytic conditions. Finally, we show that heme-specific sdAbs can be used to visualize cellular heme. In conclusion, we describe a panel of heme-specific sdAbs that when used with other approaches provide novel insights to the pathophysiology of heme. PMID:28783254

Pathogenicity and Phenotypic Characterization of Enterotoxigenic Escherichia coli Isolates from a Birth Cohort of Children in Rural Egypt

PubMed Central

Shaheen, Hind I.; Amine, Mohamed; Hassan, Khaled; Sanders, John W.; Riddle, Mark S.; Armstrong, Adam W.; Svennerholm, Ann-Mari; Sebeny, Peter J.; Klena, John D.; Young, Sylvia Y. N.; Frenck, Robert W.

2014-01-01

Enterotoxigenic Escherichia coli (ETEC) has consistently been the predominant bacterial cause of diarrhea in many birth cohort- and hospital-based studies conducted in Egypt. We evaluated the pathogenicity of ETEC isolates in a birth cohort of children living in a rural community in Egypt. Between 2004 and 2007, we enrolled and followed 348 children starting at birth until their second year of life. A stool sample and two rectal swabs were collected from children during twice-weekly visits when they presented with diarrhea and were collected every 2 weeks if no diarrhea was reported. From routine stool cultures, five E. coli-like colonies were screened for ETEC enterotoxins using a GM1 enzyme-linked immunosorbent assay (ELISA). The isolates were screened against a panel of 12 colonization factor antigens (CFAs) by a dot blot assay. A nested case-control study evaluated the association between initial or repeat excretion of ETEC and the occurrences of diarrhea. The pathogenicity of ETEC was estimated in symptomatic children compared to that in asymptomatic controls. ETEC was significantly associated with diarrhea (crude odds ratio, 1.37; 95% confidence interval [CI], 1.24 to 1.52). The distribution of ETEC enterotoxins varied between the symptomatic children (44.2% heat-labile toxin [LT], 38.5% heat-stable toxin [ST], and 17.3% LT/ST) and asymptomatic children (55.5% LT, 34.6% ST, and 9.9% LT/ST) (P < 0.001). The CFAs CFA/I (n = 61), CS3 (n = 8), CS1 plus CS3 (n = 24), CS2 plus CS3 (n = 18), CS6 (n = 45), CS5 plus CS6 (n = 11), CS7 (n = 25), and CS14 (n = 32) were frequently detected in symptomatic children, while CS6 (n = 66), CS12 (n = 51), CFA/I (n = 43), and CS14 (n = 20) were detected at higher frequencies among asymptomatic children. While all toxin phenotypes were associated with diarrheal disease after the initial exposure, only ST and LT/ST-expressing ETEC isolates (P < 0.0001) were associated with disease in repeat infections. The role of enterotoxins and

Mass production of somatic embryos expressing Escherichia coli heat-labile enterotoxin B subunit in Siberian ginseng.

PubMed

Kang, Tae-Jin; Lee, Won-Seok; Choi, Eun-Gyung; Kim, Jae-Whune; Kim, Bang-Geul; Yang, Moon-Sik

2006-01-24

The B subunit of Escherichia coli heat-labile toxin (LTB) is a potent mucosal immunogen and immunoadjuvant for co-administered antigens. In order to produce large scale of LTB for the development of edible vaccine, we used transgenic somatic embryos of Siberian ginseng, which is known as medicinal plant. When transgenic somatic embryos were cultured in 130L air-lift type bioreactor, they were developed to mature somatic embryos through somatic embryogenesis and contained approximately 0.36% LTB of the total soluble protein. Enzyme-linked immunosorbent assay indicated that the somatic embryo-synthesized LTB protein bound specifically to GM1-ganglioside, suggesting the LTB subunits formed active pentamers. Therefore, the use of the bioreactor system for expression of LTB proteins in somatic embryos allows for continuous mass production in a short-term period.

The 2.3 {angstrom} crystal structure of cholera toxin B subunit pentamer: Choleragenoid

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Rong-Guang; Westbrook, M.L.; Maulik, P.R.

1996-02-01

Cholera toxin, a heterohexameric AB{sub 5} enterotoxin released by Vibrio cholera, induces a profuse secretory diarrhea in susceptible hosts. Choleragenoid, the B subunit pentamer of cholera toxin, directs the enzymatic A subunit to its target by binding to GM{sub 1} gangliosides exposed on the luminal surface of intestinal epithelial cells. We have solved the crystal structure of choleragenoid at 2.3 {Angstrom} resolution by combining single isomorphous replacement with non-crystallographic symmetry averaging. The structure of the B subunits, and their pentameric arrangement, closely resembles that reported for the intact holotoxin (choleragen), the heat-labile enterotoxin from E. coli, and for a choleragenoid-GM{submore » 1} pentasaccharide complex. In the absence of the A subunit the central cavity of the B pentamer is a highly solvated channel. The binding of the A subunit or the receptor pentasaccharide to choleragenoid has only a modest effect on the local stereochemistry and does not perceptibly alter the subunit interface.« less

Pharmacological ascorbate and ionizing radiation (IR) increase labile iron in pancreatic cancer☆

PubMed Central

Moser, Justin C.; Rawal, Malvika; Wagner, Brett A.; Du, Juan; Cullen, Joseph J.; Buettner, Garry R.

2013-01-01

Labile iron, i.e. iron that is weakly bound and is relatively unrestricted in its redox activity, has been implicated in both the pathogenesis as well as treatment of cancer. Two cancer treatments where labile iron may contribute to their mechanism of action are pharmacological ascorbate and ionizing radiation (IR). Pharmacological ascorbate has been shown to have tumor-specific toxic effects due to the formation of hydrogen peroxide. By catalyzing the oxidation of ascorbate, labile iron can enhance the rate of formation of hydrogen peroxide; labile iron can also react with hydrogen peroxide. Here we have investigated the magnitude of the labile iron pool in tumor and normal tissue. We also examined the ability of pharmacological ascorbate and IR to change the size of the labile iron pool. Although a significant amount of labile iron was seen in tumors (MIA PaCa-2 cells in athymic nude mice), higher levels were seen in murine tissues that were not susceptible to pharmacological ascorbate. Pharmacological ascorbate and irradiation were shown to increase the labile iron in tumor homogenates from this murine model of pancreatic cancer. As both IR and pharmacological ascorbate may rely on labile iron for their effects on tumor tissues, our data suggest that pharmacological ascorbate could be used as a radio-sensitizing agent for some radio-resistant tumors. PMID:24396727

An ultrahigh-resolution mass spectrometry index to estimate natural organic matter lability

PubMed Central

D'Andrilli, Juliana; Cooper, William T; Foreman, Christine M; Marshall, Alan G

2015-01-01

Rationale Determining the chemical constituents of natural organic matter (NOM) by Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FTICRMS) remains the ultimate measure for probing its source material, evolution, and transport; however, lability and the fate of organic matter (OM) in the environment remain controversial. FTICRMS-derived elemental compositions are presented in this study to validate a new interpretative method to determine the extent of NOM lability from various environments. Methods FTICRMS data collected over the last decade from the same 9.4 tesla instrument using negative electrospray ionization at the National High Magnetic Field Laboratory in Tallahassee, Florida, was used to validate the application of a NOM lability index. Solid-phase extraction cartridges were used to isolate the NOM prior to FTICRMS; mass spectral peaks were calibrated internally by commonly identified NOM homologous series, and molecular formulae were determined for NOM composition and lability analysis. Results A molecular lability boundary (MLB) was developed from the FTICRMS molecular data, visualized from van Krevelen diagrams, dividing the data into more and less labile constituents. NOM constituents above the MLB at H/C ≥1.5 correspond to more labile material, whereas NOM constituents below the MLB, H/C <1.5, exhibit less labile, more recalcitrant character. Of all marine, freshwater, and glacial environments considered for this study, glacial ecosystems were calculated to contain the most labile OM. Conclusions The MLB extends our interpretation of FTICRMS NOM molecular data to include a metric of lability, and generally ranked the OM environments from most to least labile as glacial > marine > freshwater. Applying the MLB is useful not only for individual NOM FTICRMS studies, but also provides a lability threshold to compare and contrast molecular data with other FTICRMS instruments that survey NOM from around the world. Copyright © 2015

Transient acidosis while retrieving a fear-related memory enhances its lability

PubMed Central

Du, Jianyang; Price, Margaret P; Taugher, Rebecca J; Grigsby, Daniel; Ash, Jamison J; Stark, Austin C; Hossain Saad, Md Zubayer; Singh, Kritika; Mandal, Juthika; Wemmie, John A; Welsh, Michael J

2017-01-01

Attenuating the strength of fearful memories could benefit people disabled by memories of past trauma. Pavlovian conditioning experiments indicate that a retrieval cue can return a conditioned aversive memory to a labile state. However, means to enhance retrieval and render a memory more labile are unknown. We hypothesized that augmenting synaptic signaling during retrieval would increase memory lability. To enhance synaptic transmission, mice inhaled CO2 to induce an acidosis and activate acid sensing ion channels. Transient acidification increased the retrieval-induced lability of an aversive memory. The labile memory could then be weakened by an extinction protocol or strengthened by reconditioning. Coupling CO2 inhalation to retrieval increased activation of amygdala neurons bearing the memory trace and increased the synaptic exchange from Ca2+-impermeable to Ca2+-permeable AMPA receptors. The results suggest that transient acidosis during retrieval renders the memory of an aversive event more labile and suggest a strategy to modify debilitating memories. DOI: http://dx.doi.org/10.7554/eLife.22564.001 PMID:28650315

Virulence factors associated with cytotoxic necrotizing factor type two in bovine diarrheic and septicemic strains of Escherichia coli.

PubMed Central

Oswald, E; de Rycke, J; Lintermans, P; van Muylem, K; Mainil, J; Daube, G; Pohl, P

1991-01-01

Forty-three bovine isolates of Escherichia coli producing a second type of cytotoxic necrotizing factor (CNF2) and three K-12 strains carrying different Vir plasmids coding for CNF2 were tested for the presence of several virulence factors. Most of the strains were serum resistant (79%), produced an aerobactin (70%), and adhered to calf villi (53%); some of them produced a colicin (32%) and a hemolysin (9%). These strains were also tested by a colony hybridization assay with gene probes for six toxins (classical heat-stable [STaP and STb] and heat-labile [LT-I and LT-IIa] enterotoxins and Shiga-like toxins [SLT-I and SLT-II]) and five adhesion factors (K99, K88, 987P, F17, and F41). Only two gene probes, LT-IIa (9%) and F17A (53%), hybridized with the CNF2 strains. However, antibodies raised against F17 fimbriae did not agglutinate the strains hybridizing with the F17A probe. In contrast, all except one of these strains adhered to calf villi. Interestingly, these two properties, F17A positivity and adherence to calf villi, were the only ones expressed by the K-12 strains carrying different Vir plasmids. In conclusion, this study confirmed that CNF2-producing strains are unrelated to previously described toxigenic E. coli strains and also demonstrated that in half of the strains the production of CNF2 was associated with an adhesion factor genetically related to, but different from, F17, which is more than likely encoded by Vir plasmids. PMID:1774259

The Adjuvant LT-K63 Can Restore Delayed Maturation of Follicular Dendritic Cells and Poor Persistence of Both Protein- and Polysaccharide-Specific Antibody-Secreting Cells in Neonatal Mice

PubMed Central

Bjarnarson, Stefania P.; Adarna, Brenda C.; Benonisson, Hreinn; Del Giudice, Giuseppe

2012-01-01

Ab responses in early life are low and short-lived; therefore, induction of protective immunity requires repeated vaccinations. One of the major limitations in early-life immunity is delayed maturation of follicular dendritic cells (FDCs), which play a central role in mediating the germinal center (GC) reaction leading to production of Ab-secreting cells (AbSCs). We assessed whether a nontoxic mutant of Escherichia coli heat-labile enterotoxin (LT-K63) and CpG1826 as model adjuvants could accelerate FDC maturation and immune response in neonatal mice, using a pneumococcal polysaccharide of serotype 1 conjugated to tetanus toxoid (Pnc1-TT) as a model vaccine. In neonatal NMRI mice, a single dose of Pnc1-TT coadministered with LT-K63 enhanced Pnc1-TT–induced GC reaction. In contrast, CpG1826 had no effect. Accordingly, LT-K63, but not CpG1826, accelerated the maturation of FDC networks, detected by FDC-M2+ staining, characteristic for adult-like FDCs. This coincided with migration of MOMA-1+ macrophages into the GCs that can enhance GC reaction and B cell activation. The FDC-M2+ FDC networks colocalized with enhanced expression of TNF-α, which is critical for the maintenance of mature FDCs and is poorly expressed in neonates. The accelerated maturation of FDC networks correlated with increased frequency and prolonged persistence of polysaccharide- and protein-specific IgG+ AbSCs in spleen and bone marrow. Our data show for the first time, to our knowledge, that an adjuvant (LT-K63) can overcome delayed maturation of FDCs in neonates, enhance the GC reaction, and prolong the persistence of vaccine-specific AbSCs in the BM. These properties are attractive for parenteral vaccination in early life. PMID:22753937

Expression of non-toxic mutant of Escherichia coli heat-labile enterotoxin in tobacco chloroplasts.

PubMed

Kang, Tae-Jin; Han, So-Chon; Kim, Mi-Young; Kim, Young-Sook; Yang, Moon-Sik

2004-11-01

Chloroplast transformation systems offer unique advantages in biotechnology, including high level of foreign gene expression, maternal inheritance, and polycistronic expression. We studied chloroplast expression of LTK63 (change Ser-->Lys at position 63 in the A subunit) which is the mutant of Escherichia coli heat-labile toxin. LTK63 is devoid of any toxic activity, but still retains its mucosal adjuvanticity. The LTK63 was cloned into chloroplast targeting vector and transformed to tobacco chloroplasts by particle bombardment. PCR and Southern blot analyses confirmed stable homologous recombination of the LTK63 gene into the chloroplast genome. The amount of LTK63 protein detected in tobacco chloroplasts was approximately 3.7% of the total soluble protein. The GM1-ganglioside binding assay confirmed that chloroplast-synthesized LTB of LTK63 binds to the intestinal membrane GM1-ganglioside receptor. Thus, the expression of LTK63 in chloroplasts provides a potential route toward the development of a plant-based edible vaccine for high expression system and environmentally friendly approach.

Oral immunisation of naive and primed animals with transgenic potato tubers expressing LT-B.

PubMed

Lauterslager, T G; Florack, D E; van der Wal, T J; Molthoff, J W; Langeveld, J P; Bosch, D; Boersma, W J; Hilgers, L A

2001-03-21

The efficacy of edible vaccines produced in potato tubers was examined in mice. Transgenic plants were developed by Agrobacterium tumefaciens-mediated transformation. The antigen selected was the non-toxic B subunit of the Escherichia coli enterotoxin (recLT-B). A synthetic gene coding for recLT-B was made and optimised for expression in potato tubers and accumulation in the endoplasmic reticulum. Introduction of this gene under control of the tuber-specific patatin promoter in potato plants resulted in the production of functional, i.e. Gm1-binding, recLT-B pentamers in tubers. Selected tubers containing about 13 microg of recLT-B per gram fresh weight were used for immunisation. Subcutaneous immunisation with an extract of recLT-B tubers yielded high antibody titres in serum that were similar to those obtained with bacterial recLT-B. The efficacy of oral administration of recLT-B tubers was determined by measuring mucosal and systemic immune responses in naive and primed mice. Animals were primed by subcutaneous injection of an extract of recLT-B tuber plus adjuvant. Naive and primed mice were fed 5 g of tubers ( approximately 65 microg of recLT-B) or were intubated intragastrically with 0.4 ml of tuber extract ( approximately 2 microg of recLT-B). In naive mice, feeding recLT-B tubers or intubation of tuber extract did not induce detectable anti-LT antibody titres. In primed animals, however, oral immunisation resulted in significant anti-LT IgA antibody responses in serum and faeces. Intragastric intubation of tuber extract revealed higher responses than feeding of tubers. These results indicate clearly that functional recLT-B can be produced in potato tubers, that this recombinant protein is immunogenic and that oral administration thereof elicits both systemic and local IgA responses in parentally primed, but not naive, animals.

Current Progress in Developing Subunit Vaccines against Enterotoxigenic Escherichia coli-Associated Diarrhea

PubMed Central

Sack, David A.

2015-01-01

Diarrhea continues to be a leading cause of death in children <5 years of age, and enterotoxigenic Escherichia coli (ETEC) is the most common bacterial cause of children's diarrhea. Currently, there are no available vaccines against ETEC-associated diarrhea. Whole-cell vaccine candidates have been under development but require further improvements because they provide inadequate protection and produce unwanted adverse effects. Meanwhile, a newer approach using polypeptide or subunit vaccine candidates focusing on ETEC colonization factor antigens (CFAs) and enterotoxins, the major virulence determinants of ETEC diarrhea, shows substantial promise. A conservative CFA/I adhesin tip antigen and a CFA MEFA (multiepitope fusion antigen) were shown to induce cross-reactive antiadhesin antibodies that protected against adherence by multiple important CFAs. Genetic fusion of toxoids derived from ETEC heat-labile toxin (LT) and heat-stable toxin (STa) induced antibodies neutralizing both enterotoxins. Moreover, CFA-toxoid MEFA polypeptides, generated by fusing CFA MEFA to an STa-LT toxoid fusion, induced antiadhesin antibodies that broadly inhibited adherence of the seven most important ETEC CFAs associated with about 80% of the diarrhea cases caused by ETEC strains with known CFAs. This same antigen preparation also induced antitoxin antibodies that neutralized both toxins that are associated with all cases of ETEC diarrhea. Results from these studies suggest that polypeptide or subunit vaccines have the potential to effectively protect against ETEC diarrhea. In addition, novel adhesins and mucin proteases have been investigated as potential alternatives or, more likely, additional antigens for ETEC subunit vaccine development. PMID:26135975

Human Papillomavirus Virus-Like Particles Are Efficient Oral Immunogens when Coadministered with Escherichia coli Heat-Labile Enterotoxin Mutant R192G or CpG DNA

PubMed Central

Gerber, S.; Lane, C.; Brown, D. M.; Lord, E.; DiLorenzo, M.; Clements, J. D.; Rybicki, E.; Williamson, A.-L.; Rose, R. C.

2001-01-01

Certain human papillomaviruses (HPVs) cause most cervical cancer, which remains a significant source of morbidity and mortality among women worldwide. HPV recombinant virus-like particles (VLPs) are promising vaccine candidates for controlling anogenital HPV disease and are now being evaluated as a parenteral vaccine modality in human subjects. Vaccines formulated for injection generally are more costly, more difficult to administer, and less acceptable to recipients than are mucosally administered vaccines. Since oral delivery represents an attractive alternative to parenteral injection for large-scale human vaccination, the oral immunogenicity of HPV type 11 (HPV-11) VLPs in mice was previously investigated; it was found that a modest systemic neutralizing antibody response was induced (R. C. Rose, C. Lane, S. Wilson, J. A. Suzich, E. Rybicki, and A. L. Williamson, Vaccine 17:2129–2135, 1999). Here we examine whether VLPs of other genotypes may also be immunogenic when administered orally and whether mucosal adjuvants can be used to enhance VLP oral immunogenicity. We show that HPV-16 and HPV-18 VLPs are immunogenic when administered orally and that oral coadministration of these antigens with Escherichia coli heat-labile enterotoxin (LT) mutant R192G (LT R192G) or CpG DNA can significantly improve anti-VLP humoral responses in peripheral blood and in genital mucosal secretions. Our results also suggest that LT R192G may be superior to CpG DNA in this ability. These findings support the concept of oral immunization against anogenital HPV disease and suggest that clinical studies involving this approach may be warranted. PMID:11312347

Repeated Labilization-Reconsolidation Processes Strengthen Declarative Memory in Humans

PubMed Central

Forcato, Cecilia; Rodríguez, María L. C.; Pedreira, María E.

2011-01-01

The idea that memories are immutable after consolidation has been challenged. Several reports have shown that after the presentation of a specific reminder, reactivated old memories become labile and again susceptible to amnesic agents. Such vulnerability diminishes with the progress of time and implies a re-stabilization phase, usually referred to as reconsolidation. To date, the main findings describe the mechanisms associated with the labilization-reconsolidation process, but little is known about its functionality from a biological standpoint. Indeed, two functions have been proposed. One suggests that destabilization of the original memory after the reminder allows the integration of new information into the background of the original memory (memory updating), and the other suggests that the labilization-reconsolidation process strengthens the original memory (memory strengthening). We have previously reported the reconsolidation of human declarative memories, demonstrating memory updating in the framework of reconsolidation. Here we deal with the strengthening function attributed to the reconsolidation process. We triggered labilization-reconsolidation processes successively by repeated presentations of the proper reminder. Participants learned an association between five cue-syllables and their respective response-syllables. Twenty-four hours later, the paired-associate verbal memory was labilized by exposing the subjects to one, two or four reminders. The List-memory was evaluated on Day 3 showing that the memory was improved when at least a second reminder was presented in the time window of the first labilization-reconsolidation process prompted by the earlier reminder. However, the improvement effect was revealed on Day 3, only when at least two reminders were presented on Day2 and not as a consequence of only retrieval. Therefore, we propose central concepts for the reconsolidation process, emphasizing its biological role and the parametrical constrains

A toxin-antitoxin module as a target for antimicrobial development.

PubMed

Lioy, Virginia S; Rey, Oscar; Balsa, Dolors; Pellicer, Teresa; Alonso, Juan C

2010-01-01

The emergence and spread of pathogenic bacteria that have become resistant to multiple antibiotics through lateral gene transfer have created the need of novel antimicrobials. Toxin-antitoxin (TA) modules, which have been implicated in plasmid maintenance and stress management, are ubiquitous among plasmids from vancomycin or methicillin resistant bacteria. In the Streptococcus pyogenes pSM19035-encoded TA loci, the labile epsilon antitoxin binds to free zeta toxin and neutralizes it. When the zeta toxin is freed from the epsilon antitoxin, it induces a reversible state of growth arrest with a drastic reduction on the rate of replication, transcription and translation. However, upon prolonged zeta toxin action, the cells can no longer be rescued from their stasis state. A compound that disrupts the epsilon.zeta interaction can be considered as an attractive antimicrobial agent. Gene epsilon was fused to luc (Luc-epsilon antitoxin) and zeta to the gfp gene (zeta-GFP). Luc-epsilon or epsilon antitoxin neutralizes the toxic effect of the zeta or zeta-GFP toxin. In the absence of the antitoxin, free zeta or zeta-GFP triggers a reversible loss of cell proliferation, but the zetaK46A-GFP variant fails to block growth. Bioluminescence resonance energy transfer (BRET) assay was developed for high-throughput screening (HTS). To develop the proper controls, molecular dynamics studies were used to predict that the Asp18 and/or Glu22 residues might be relevant for epsilon.zeta interaction. Luc-epsilon efficiently transfers the excited energy to the fluorescent acceptor molecule (zeta-GFP or zetaK46A-GFP) and rendered high bioluminescence BRET signals. The exchange of Asp18 to Ala from zeta (D18A) affects Luc-epsilon.zetaD18A K46A-GFP interaction. In this study, we validate the hypothesis that it is possible to disrupt a TA module and offer a novel and unexploited targets to fight against antibiotic-resistant strains. Copyright 2009 Elsevier Inc. All rights reserved.

A novel formulation of L-thyroxine (L-T4) reduces the problem of L-T4 malabsorption by coffee observed with traditional tablet formulations.

PubMed

Vita, Roberto; Saraceno, Giovanna; Trimarchi, Francesco; Benvenga, Salvatore

2013-02-01

The purpose of this work is to evaluate if the coffee-associated malabsorption of tablet levothyroxine (L-T4) is reduced by soft gel capsule. We recruited 8 patients with coffee-associated L-T4 malabsorption including one hypothyroid patient. For 6 months, the patients were switched to the capsule maintaining the L-T4 daily dose. Patients took the capsule with water, having coffee 1 h later (proper habit, PH) on days 1-90, or with coffee ≤ 5 min later (improper habit, IH) on days 91-180. After 6 months, 2 patients volunteered for an acute loading test of 600 μg L-T4 (capsule) ingested with water (PH) or with coffee (IH). In the single hypothyroid patient, the post-switch TSH ranged 0.06-0.16 mU/L (PH) versus 5.8-22.4 mU/L pre-switch (PH) and 0.025-0.29 mU/L (IH) versus 26-34 mU/L pre-switch (IH). In the other 7 patients, post-switch TSH was 0.41 ± 0.46 (PH) versus 0.28 ± 0.20 pre-switch (PH) (P = 0.61) and 0.34 ± 0.30 (IH) versus 1.23 ± 1.47 pre-switch (IH) (P < 0.001). Importantly, TSH levels in PH versus IH habit did not differ post-switch (P = 0.90), but they did pre-switch (P < 0.0001). The proportions of post-switch TSH levels <0.10 mU/L with PH (33.3 %) or with IH (33.3 %) were borderline significantly greater than the corresponding pre-switch levels with PH (10.3 %) (P = 0.088) or with IH (0 %) (P = 0.0096). In the two volunteers, the L-T4 loading test showed that coffee influenced L-T4 pharmacokinetics minimally. Soft gel capsules can be used in patients who are unable/unwilling to change their IH of taking L-T4.

Multiple defects in innate and adaptive immunologic function in NOD/LtSz-scid mice.

PubMed

Shultz, L D; Schweitzer, P A; Christianson, S W; Gott, B; Schweitzer, I B; Tennent, B; McKenna, S; Mobraaten, L; Rajan, T V; Greiner, D L

1995-01-01

The scid mutation was backcrossed ten generations onto the NOD/Lt strain background, resulting in an immunodeficient stock (NOD/LtSz-scid/scid) with multiple defects in adaptive as well as nonadaptive immunologic function. NOD/LtSz-scid/scid mice lack functional lymphoid cells and show little or no serum Ig with age. Although NOD/(Lt-)+/+ mice develop T cell-mediated autoimmune, insulin-dependent diabetes mellitus, NOD/LtSz-scid/scid mice are both insulitis- and diabetes-free throughout life. However, because of a high incidence of thymic lymphomas, the mean lifespan of this congenic stock is only 8.5 mo under specific pathogen-free conditions. After i.v. injection of human CEM T-lymphoblastoid cells, splenic engraftment of these cells was fourfold greater in NOD/LtSz-scid/scid mice than in C.B17/Sz-scid/scid mice. Although C.B-17Sz-scid/scid mice exhibit robust NK cell activity, this activity is markedly reduced in both NOD/(Lt-)+/+ and NOD/LtSz-scid/scid mice. Presence of a functionally less mature macrophage population in NOD/LtSz-scid/scid vs C.B-17Sz-scid/scid mice is indicated by persistence in the former of the NOD/Lt strain-specific defect in LPS-stimulated IL-1 secretion by marrow-derived macrophages. Although C.B-17Sz-scid/scid and C57BL/6Sz-scid/scid mice have elevated serum hemolytic complement activity compared with their respective +/+ controls, both NOD/(LtSz-)+/+ and NOD/LtSz-scid/scid mice lack this activity. Age-dependent increases in serum Ig levels (> 1 micrograms/ml) were observed in only 2 of 30 NOD/LtSz-scid/scid mice vs 21 of 29 C.B-17/Sz-scid/scid animals. The multiple defects in innate and adaptive immunity unique to the NOD/LtSz-scid/scid mouse provide an excellent in vivo environment for reconstitution with human hematopoietic cells.

Immunological and functional comparison between Clostridium perfringens iota toxin, C. spiroforme toxin, and anthrax toxins.

PubMed

Perelle, S; Scalzo, S; Kochi, S; Mock, M; Popoff, M R

1997-01-01

Clostridium perfringens iota and C. spiroforme toxins consist of two separate proteins. One is the binding component and the other the enzymatic component. The two toxins secreted by Bacillus anthracis are composed of binary combinations of three proteins: protective antigen, lethal factor, and edema factor. As shown by Western blotting and ELISA, the binding component of anthrax toxin shares common epitopes with that of iota toxin and C. spiroforme toxin which are closely related immunologically. However, no functional complementation was observed between iota toxin and anthrax toxin components. The binding components can form toxins active on macrophages only in combination with their respective enzymatic components. Agents which prevent acidification of endosomes do not have the same effects on anthrax toxin activity as they do on iota and C. spiroforme toxins. Therefore, the mechanisms of entry into the cells are presumably different. Since the binding components of anthrax toxins and iota toxin share a conserved putative translocation domain, these binding components could have a common mode of insertion into the cell membranes.

Construction of hierarchically porous metal–organic frameworks through linker labilization

DOE PAGES

Yuan, Shuai; Zou, Lanfang; Qin, Jun-Sheng; ...

2017-05-25

One major goal of metal–organic framework (MOF) research is the expansion of pore size and volume. Although many approaches have been attempted to increase the pore size of MOF materials, it is still a challenge to construct MOFs with precisely customized pore apertures for specific applications. W present a new method, namely linker labilization, to increase the MOF porosity and pore size, giving rise to hierarchical-pore architectures. Microporous MOFs with robust metal nodes and pro-labile linkers were initially synthesized. The mesopores were subsequently created as crystal defects through the splitting of a pro-labile-linker and the removal of the linker fragmentsmore » by acid treatment. We also demonstrate that linker labilization method can create controllable hierarchical porous structures in stable MOFs, which facilitates the diffusion and adsorption process of guest molecules to improve the performances of MOFs in adsorption and catalysis.« less

Construction of hierarchically porous metal-organic frameworks through linker labilization

NASA Astrophysics Data System (ADS)

Yuan, Shuai; Zou, Lanfang; Qin, Jun-Sheng; Li, Jialuo; Huang, Lan; Feng, Liang; Wang, Xuan; Bosch, Mathieu; Alsalme, Ali; Cagin, Tahir; Zhou, Hong-Cai

2017-05-01

A major goal of metal-organic framework (MOF) research is the expansion of pore size and volume. Although many approaches have been attempted to increase the pore size of MOF materials, it is still a challenge to construct MOFs with precisely customized pore apertures for specific applications. Herein, we present a new method, namely linker labilization, to increase the MOF porosity and pore size, giving rise to hierarchical-pore architectures. Microporous MOFs with robust metal nodes and pro-labile linkers were initially synthesized. The mesopores were subsequently created as crystal defects through the splitting of a pro-labile-linker and the removal of the linker fragments by acid treatment. We demonstrate that linker labilization method can create controllable hierarchical porous structures in stable MOFs, which facilitates the diffusion and adsorption process of guest molecules to improve the performances of MOFs in adsorption and catalysis.

Construction of hierarchically porous metal–organic frameworks through linker labilization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yuan, Shuai; Zou, Lanfang; Qin, Jun-Sheng

One major goal of metal–organic framework (MOF) research is the expansion of pore size and volume. Although many approaches have been attempted to increase the pore size of MOF materials, it is still a challenge to construct MOFs with precisely customized pore apertures for specific applications. W present a new method, namely linker labilization, to increase the MOF porosity and pore size, giving rise to hierarchical-pore architectures. Microporous MOFs with robust metal nodes and pro-labile linkers were initially synthesized. The mesopores were subsequently created as crystal defects through the splitting of a pro-labile-linker and the removal of the linker fragmentsmore » by acid treatment. We also demonstrate that linker labilization method can create controllable hierarchical porous structures in stable MOFs, which facilitates the diffusion and adsorption process of guest molecules to improve the performances of MOFs in adsorption and catalysis.« less

Non-labile silver species in biosolids remain stable throughout ...

EPA Pesticide Factsheets

Increasing commercial use of nanosilver has focussed attention on the fate of silver (Ag) in the wastewater release pathway. This paper reports the speciation and lability of Ag in archived, stockpiled, and contemporary biosolids from the UK, USA and Australia, and indicates that biosolids Ag concentrations have decreased significantly over recent decades. XANES revealed the importance of reduced-sulfur binding environments for Ag speciation in materials ranging from freshly produced sludge to biosolids weathered under ambient environmental conditions for more than 50 years. Isotopic dilution with 110mAg showed that Ag was predominantly non-labile in both fresh and aged biosolids (13.7% mean lability), with E-values ranging from 0.3 to 60 mg/kg and 5 mM CaNO3 extractable Ag from 1.2 to 609 µg/kg (0.002 - 3.4% of the total Ag). This study indicates that at the time of soil application, biosolids Ag will be predominantly Ag-sulfides and characterised by low isotopic lability. This paper presents an overview of biosolids Ag chemistry in historic and contemporary biosolids sourced from the UK, USA and Australia from the 1950s until today by drawing on a unique collection of archived, stockpiled and contemporary biosolids samples. Characteristics of biosolids Ag chemistry determined in this study included total Ag measurement by neutron activation analysis (NAA); the assessment of Ag lability by 110mAg isotopic dilution (E-values); and Ag speciation by X-ray Absorp

Freshwater processing of terrestrial dissolved organic matter: What governs lability?

NASA Astrophysics Data System (ADS)

D'Andrilli, J.; Smith, H. J.; Junker, J. R.; Scholl, E. A.; Foreman, C. M.

2016-12-01

Aquatic and terrestrial ecosystems are linked through the transfer of energy and materials. Allochthonous organic matter (OM) is central to freshwater ecosystem function, influencing local food webs, trophic state, and nutrient availability. In order to understand the nature and fate of OM from inland headwaters to the open ocean, it is imperative to understand the links between OM lability and ecosystem function. Thus, biological, chemical, and physical factors need to be evaluated together to inform our understanding of environmental lability. We performed a laboratory processing experiment on naturally occurring OM leachates from riparian leaves, grasses, and pine needles. Measures of water chemistry, OM optical and molecular characterization, bacterial abundances, microbial assemblage composition, respiration, and C:N:P were integrated to discern the nature and fate of labile and recalcitrant OM in a freshwater stream. Peak processing of all OM sources in the stream water occurred after two days, with spikes in bacterial cell abundances, respiration rates, microbial assemblage shifts, and maximum C utilization. Respiration rates and microbial assemblages were dependent on the degree of lability of the OM molecular composition. Within the first few days, no differences in respiration rates were observed between leachate sources, however, beyond day five, the rates diverged with C processing efficiency correlated with OM lability. Originally comprised of amino acid-like, labile fluorescent species, the inoculated stream water OM became more recalcitrant after 16 days, indicating humification processing over time. Our study highlights the importance of interdisciplinary approaches for understanding the processing and fate of OM in aquatic ecosystems.

Ganglioside structure dictates signal transduction by cholera toxin and association with caveolae-like membrane domains in polarized epithelia.

PubMed

Wolf, A A; Jobling, M G; Wimer-Mackin, S; Ferguson-Maltzman, M; Madara, J L; Holmes, R K; Lencer, W I

1998-05-18

In polarized cells, signal transduction by cholera toxin (CT) requires apical endocytosis and retrograde transport into Golgi cisternae and perhaps ER (Lencer, W.I., C. Constable, S. Moe, M. Jobling, H.M. Webb, S. Ruston, J.L. Madara, T. Hirst, and R. Holmes. 1995. J. Cell Biol. 131:951-962). In this study, we tested whether CT's apical membrane receptor ganglioside GM1 acts specifically in toxin action. To do so, we used CT and the related Escherichia coli heat-labile type II enterotoxin LTIIb. CT and LTIIb distinguish between gangliosides GM1 and GD1a at the cell surface by virtue of their dissimilar receptor-binding B subunits. The enzymatically active A subunits, however, are homologous. While both toxins bound specifically to human intestinal T84 cells (Kd approximately 5 nM), only CT elicited a cAMP-dependent Cl- secretory response. LTIIb, however, was more potent than CT in eliciting a cAMP-dependent response from mouse Y1 adrenal cells (toxic dose 10 vs. 300 pg/well). In T84 cells, CT fractionated with caveolae-like detergent-insoluble membranes, but LTIIb did not. To investigate further the relationship between the specificity of ganglioside binding and partitioning into detergent-insoluble membranes and signal transduction, CT and LTIIb chimeric toxins were prepared. Analysis of these chimeric toxins confirmed that toxin-induced signal transduction depended critically on the specificity of ganglioside structure. The mechanism(s) by which ganglioside GM1 functions in signal transduction likely depends on coupling CT with caveolae or caveolae-related membrane domains.

Shifting Prevalence of Major Diarrheal Pathogens in Patients Seeking Hospital Care during Floods in 1998, 2004, and 2007 in Dhaka, Bangladesh

PubMed Central

Harris, Aaron M.; Chowdhury, Fahima; Begum, Yasmin Ara; Khan, Ashraful Islam; Faruque, Abu S. G.; Svennerholm, Ann-Mari; Harris, Jason B.; Ryan, Edward T.; Cravioto, Alejandro; Calderwood, Stephen B.; Qadri, Firdausi

2009-01-01

Bangladesh experienced severe flooding and diarrheal epidemics in 2007. We compared flood data from 2007 with 2004 and 1998 for diarrheal patients attending the ICDDR,B hospital in Dhaka. In 2007, Vibrio cholerae O1 (33%), rotavirus (12%), and enterotoxigenic Escherichia coli (ETEC) (12%) were most prevalent. More severe dehydration was seen in 2007 compared with 2004 and 1998 (P < 0.001). In 2007, V. cholerae O1 Inaba (52%) and Ogawa (48%) were seen, whereas in 2004 and 1998 it was primarily Inaba and the Ogawa types, respectively (P < 0.001). In 2007, 51% of ETEC produced the heat labile toxin (LT) (P < 0.001 compared with 2004), 22% expressed the heat stable (ST) (P < 0.001), and 27% were ST/LT positive (P = 0.231). The CS7 colonization factor (CF) was the most prevalent in 2007 (20% compared with 6% in 2004; P = 0.05). Our findings demonstrate alterations in clinical features and phenotypic changes of major bacterial pathogens in the recent Bangladesh flood. PMID:18981509

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...

BtoxDB: a comprehensive database of protein structural data on toxin-antitoxin systems.

PubMed

Barbosa, Luiz Carlos Bertucci; Garrido, Saulo Santesso; Marchetto, Reinaldo

2015-03-01

Toxin-antitoxin (TA) systems are diverse and abundant genetic modules in prokaryotic cells that are typically formed by two genes encoding a stable toxin and a labile antitoxin. Because TA systems are able to repress growth or kill cells and are considered to be important actors in cell persistence (multidrug resistance without genetic change), these modules are considered potential targets for alternative drug design. In this scenario, structural information for the proteins in these systems is highly valuable. In this report, we describe the development of a web-based system, named BtoxDB, that stores all protein structural data on TA systems. The BtoxDB database was implemented as a MySQL relational database using PHP scripting language. Web interfaces were developed using HTML, CSS and JavaScript. The data were collected from the PDB, UniProt and Entrez databases. These data were appropriately filtered using specialized literature and our previous knowledge about toxin-antitoxin systems. The database provides three modules ("Search", "Browse" and "Statistics") that enable searches, acquisition of contents and access to statistical data. Direct links to matching external databases are also available. The compilation of all protein structural data on TA systems in one platform is highly useful for researchers interested in this content. BtoxDB is publicly available at http://www.gurupi.uft.edu.br/btoxdb. Copyright © 2015 Elsevier Ltd. All rights reserved.

The Application of LT-Table in TRIZ Contradiction Resolving Process

NASA Astrophysics Data System (ADS)

Wei, Zihui; Li, Qinghai; Wang, Donglin; Tian, Yumei

TRIZ is used to resolve invention problems. ARIZ is the most powerful systematic method which integrates all of TRIZ heuristics. Definition of ideal final result (IFR), identification of contradictions and resource utilization are main lines of ARIZ. But resource searching of ARIZ has fault of blindness. Alexandr sets up mathematical model of transformation of the hereditary information in an invention problem using the theory of catastrophes, and provides method of resource searching using LT-table. The application of LT-table on contradiction resolving is introduced. Resource utilization using LT-table is joined into ARIZ step as an addition of TRIZ, apply this method in separator paper punching machine design.

The catalytic A1 domains of cholera toxin and heat-labile enterotoxin are potent DNA adjuvants that evoke mixed Th1/Th17 cellular immune responses

PubMed Central

Bagley, Kenneth; Xu, Rong; Ota-Setlik, Ayuko; Egan, Michael; Schwartz, Jennifer; Fouts, Timothy

2015-01-01

DNA encoded adjuvants are well known for increasing the magnitude of cellular and/or humoral immune responses directed against vaccine antigens. DNA adjuvants can also tune immune responses directed against vaccine antigens to better protect against infection of the target organism. Two potent DNA adjuvants that have unique abilities to tune immune responses are the catalytic A1 domains of Cholera Toxin (CTA1) and Heat-Labile Enterotoxin (LTA1). Here, we have characterized the adjuvant activities of CTA1 and LTA1 using HIV and SIV genes as model antigens. Both of these adjuvants enhanced the magnitude of antigen-specific cellular immune responses on par with those induced by the well-characterized cytokine adjuvants IL-12 and GM-CSF. CTA1 and LTA1 preferentially enhanced cellular responses to the intracellular antigen SIVmac239-gag over those for the secreted HIVBaL-gp120 antigen. IL-12, GM-CSF and electroporation did the opposite suggesting differences in the mechanisms of actions of these diverse adjuvants. Combinations of CTA1 or LTA1 with IL-12 or GM-CSF generated additive and better balanced cellular responses to both of these antigens. Consistent with observations made with the holotoxin and the CTA1-DD adjuvant, CTA1 and LTA1 evoked mixed Th1/Th17 cellular immune responses. Together, these results show that CTA1 and LTA1 are potent DNA vaccine adjuvants that favor the intracellular antigen gag over the secreted antigen gp120 and evoke mixed Th1/Th17 responses against both of these antigens. The results also indicate that achieving a balanced immune response to multiple intracellular and extracellular antigens delivered via DNA vaccination may require combining adjuvants that have different and complementary mechanisms of action. PMID:26042527

Controlled study on enteropathogens in travellers returning from the tropics with and without diarrhoea.

PubMed

Paschke, C; Apelt, N; Fleischmann, E; Perona, P; Walentiny, C; Löscher, T; Herbinger, K-H

2011-08-01

Diarrhoea is the most frequent health problem among travellers in the tropics. However, data on the spectrum and relevance of enteropathogens in international travellers with and without diarrhoea are limited. Stool samples from 114 cases of diarrhoea in travellers returning from the tropics were collected for microbiological examination and PCR for norovirus genogroups I and II, enteroaggregative Escherichia coli (EAEC), and enterotoxigenic E. coli (ETEC) producing heat-labile toxin (LT) and heat-stable toxin (ST). Travel and laboratory data of cases were compared with those of 56 travellers without diarrhoea. Among cases, EAEC was found in 45% of stool samples, followed by LT-ETEC (20%), ST-ETEC (16%), Blastocystis hominis (15%), Campylobacter jejuni (12%), norovirus (11%), Giardia lamblia (6%), Shigella spp. (6%), and Salmonella spp., Cryptosporidium spp., and Cyclospora cayetanensis (3% each). However, only for EAEC, ST-ETEC, Blastocystis and Campylobacter was the prevalence significantly higher among cases than among controls. Co-infections were common: 61% for cases and 13% for controls. The most common travel destination was Asia (54%), followed by Africa (35%) and Latin America (9%). The highest relative risk for diarrhoea was calculated for travellers to West Africa, East Africa, and South Asia. In this study, EAEC, LT-ETEC and ST-ETEC were detected most frequently in cases of travellers' diarrhoea. Although enteric infections with EAEC, ST-ETEC and Campylobacter often cause diarrhoea, the pathogenetic relevance remains unclear for most of the other enteropathogens, because of significant prevalence rates also being seen in controls without diarrhoea and the high frequency of co-infections. © 2010 The Authors. Clinical Microbiology and Infection © 2010 European Society of Clinical Microbiology and Infectious Diseases.

SuperLab LT: Evaluation and Uses in Teaching Experimental Psychology

ERIC Educational Resources Information Center

Ragozzine, Frank

2002-01-01

I describe and evaluate SuperLab LT (Chase & Abboud, 1990), a software package that enables students to replicate classic experiments in cognitive psychology. I also discuss the package with respect to its uses in teaching an undergraduate course in Experimental Psychology. Although the package has minor flaws, SuperLab LT provides numerous…

Memory expression is independent of memory labilization/reconsolidation.

PubMed

Barreiro, Karina A; Suárez, Luis D; Lynch, Victoria M; Molina, Víctor A; Delorenzi, Alejandro

2013-11-01

There is growing evidence that certain reactivation conditions restrict the onset of both the destabilization phase and the restabilization process or reconsolidation. However, it is not yet clear how changes in memory expression during the retrieval experience can influence the emergence of the labilization/reconsolidation process. To address this issue, we used the context-signal memory model of Chasmagnathus. In this paradigm a short reminder that does not include reinforcement allows us to evaluate memory labilization and reconsolidation, whereas a short but reinforced reminder restricts the onset of such a process. The current study investigated the effects of the glutamate antagonists, APV (0.6 or 1.5 μg/g) and CNQX (1 μg/g), prior to the reminder session on both behavioral expression and the reconsolidation process. Under conditions where the reminder does not initiate the labilization/reconsolidation process, APV prevented memory expression without affecting long-term memory retention. In contrast, APV induced amnesic effects in the long-term when administered before a reminder session that triggers reconsolidation. Under the present parametric conditions, the administration of CNQX prior to the reminder that allows memory to enter reconsolidation impairs this process without disrupting memory expression. Overall, the present findings suggest that memory reactivation--but not memory expression--is necessary for labilization and reconsolidation. Retrieval and memory expression therefore appear not to be interchangeable concepts. Copyright © 2013 Elsevier Inc. All rights reserved.

Impact of Labile Zinc on Heart Function: From Physiology to Pathophysiology

PubMed Central

Turan, Belma; Tuncay, Erkan

2017-01-01

Zinc plays an important role in biological systems as bound and histochemically reactive labile Zn2+. Although Zn2+ concentration is in the nM range in cardiomyocytes at rest and increases dramatically under stimulation, very little is known about precise mechanisms controlling the intracellular distribution of Zn2+ and its variations during cardiac function. Recent studies are focused on molecular and cellular aspects of labile Zn2+ and its homeostasis in mammalian cells and growing evidence clarified the molecular mechanisms underlying Zn2+-diverse functions in the heart, leading to the discovery of novel physiological functions of labile Zn2+ in parallel to the discovery of subcellular localization of Zn2+-transporters in cardiomyocytes. Additionally, important experimental data suggest a central role of intracellular labile Zn2+ in excitation-contraction coupling in cardiomyocytes by shaping Ca2+ dynamics. Cellular labile Zn2+ is tightly regulated against its adverse effects through either Zn2+-transporters, Zn2+-binding molecules or Zn2+-sensors, and, therefore plays a critical role in cellular signaling pathways. The present review summarizes the current understanding of the physiological role of cellular labile Zn2+ distribution in cardiomyocytes and how a remodeling of cellular Zn2+-homeostasis can be important in proper cell function with Zn2+-transporters under hyperglycemia. We also emphasize the recent investigations on Zn2+-transporter functions from the standpoint of human heart health to diseases together with their clinical interest as target proteins in the heart under pathological condition, such as diabetes. PMID:29137144

Impact of Labile Zinc on Heart Function: From Physiology to Pathophysiology.

PubMed

Turan, Belma; Tuncay, Erkan

2017-11-12

Zinc plays an important role in biological systems as bound and histochemically reactive labile Zn 2+ . Although Zn 2+ concentration is in the nM range in cardiomyocytes at rest and increases dramatically under stimulation, very little is known about precise mechanisms controlling the intracellular distribution of Zn 2+ and its variations during cardiac function. Recent studies are focused on molecular and cellular aspects of labile Zn 2+ and its homeostasis in mammalian cells and growing evidence clarified the molecular mechanisms underlying Zn 2+ -diverse functions in the heart, leading to the discovery of novel physiological functions of labile Zn 2+ in parallel to the discovery of subcellular localization of Zn 2+ -transporters in cardiomyocytes. Additionally, important experimental data suggest a central role of intracellular labile Zn 2+ in excitation-contraction coupling in cardiomyocytes by shaping Ca 2+ dynamics. Cellular labile Zn 2+ is tightly regulated against its adverse effects through either Zn 2+ -transporters, Zn 2+ -binding molecules or Zn 2+ -sensors, and, therefore plays a critical role in cellular signaling pathways. The present review summarizes the current understanding of the physiological role of cellular labile Zn 2+ distribution in cardiomyocytes and how a remodeling of cellular Zn 2+ -homeostasis can be important in proper cell function with Zn 2+ -transporters under hyperglycemia. We also emphasize the recent investigations on Zn 2+ -transporter functions from the standpoint of human heart health to diseases together with their clinical interest as target proteins in the heart under pathological condition, such as diabetes.

DNA lability induced by nimustine and ramustine in rat glioma cells.

PubMed Central

Mineura, K; Fushimi, S; Itoh, Y; Kowada, M

1988-01-01

The DNA labile sites induced by two nitrosoureas, nimustine (ACNU) and ramustine (MCNU) synthesised in Japan, have been examined in highly reiterated DNA sequences of rat glioma cells. Reiterated fragments of 167 and 203 base pairs (bp), obtained after Hind III and Hae III restriction endonuclease digestion of rat glioma cells DNA, were used as target DNA sequences to determine the labile sites. In vitro reaction with ACNU and MCNU resulted in scission products corresponding to the locations of guanine. Subsequent piperidine hydrolysis produced more frequent breaks of the phosphodiester bonds at guanine positions, thus forming alkali-labile sites. Images PMID:3236017

Elemental composition and functional groups in soil labile organic matter fractions

USDA-ARS?s Scientific Manuscript database

Labile organic matter fractions are major components involved in nutrient cycle in soil. In this chapter, we examine three labile organic matter fraction: light fraction (LF), humic acid (HA) and fulvic acid (HA) in Alabama cotton soils (ultisol) amended with chemical fertilizer (NH4NO3) and poult...

Genetic influences on ovulation of primary oocytes in LT/Sv strain mice.

PubMed

Everett, Clare A; Auchincloss, Catherine A; Kaufman, Matthew H; Abbott, Catherine M; West, John D

2004-11-01

A high proportion of LT/Sv strain oocytes arrest in meiotic metaphase I (MI) and are ovulated as diploid primary oocytes rather than haploid secondary oocytes. (Mus musculus castaneus x LT/SvKau)F1 x LT/SvKau backcross females were analysed for the proportion of oocytes that arrested in MI and typed by PCR for a panel of microsatellite DNA sequences (simple sequence repeat polymorphisms) that differed between strain LT/SvKau and M. m. castaneus. This provided a whole genome scan of 86 genetic markers distributed over all 19 autosomes and the X chromosome, and revealed genetic linkage of the MI arrest phenotype to markers on chromosomes 1 and 9. Identification of these two chromosomal regions should facilitate the identification of genes involved in mammalian oocyte maturation and the control of meiosis.

Non-labile Soil Nitrogen Retention beneath Three Tree Species in a Tropical Plantation

Treesearch

Jason P. Kaye; Dan Binkley; Xiaoming Zou

2002-01-01

Soil organic matter is the largest sink for N additions to forests. Species composition may affect soilNretention by altering the amount or proportion of added N stored in non-labile organic pools. We measured 15N tracer retention in labile and non-labile pools of surface (0–20 cm) mineral soils, 7 yr after the tracer was applied to a 9 yr-old Puerto Rican tree...

Proteomic analysis of enterotoxigenic Escherichia coli (ETEC) in neutral and alkaline conditions.

PubMed

Gonzales-Siles, Lucia; Karlsson, Roger; Kenny, Diarmuid; Karlsson, Anders; Sjöling, Åsa

2017-01-07

Enterotoxigenic Escherichia coli (ETEC) is a major cause of diarrhea in children and travelers to endemic areas. Secretion of the heat labile AB 5 toxin (LT) is induced by alkaline conditions. In this study, we determined the surface proteome of ETEC exposed to alkaline conditions (pH 9) as compared to neutral conditions (pH 7) using a LPI Hexalane FlowCell combined with quantitative proteomics. Relative quantitation with isobaric labeling (TMT) was used to compare peptide abundance and their corresponding proteins in multiple samples at MS/MS level. For protein identification and quantification samples were analyzed using either a 1D-LCMS or a 2D-LCMS approach. Strong up-regulation of the ATP synthase operon encoding F1Fo ATP synthase and down-regulation of proton pumping proteins NuoF, NuoG, Ndh and WrbA were detected among proteins involved in regulating the proton and electron transport under alkaline conditions. Reduced expression of proteins involved in osmotic stress was found at alkaline conditions while the Sec-dependent transport over the inner membrane and outer membrane protein proteins such as OmpA and the β-Barrel Assembly Machinery (BAM) complex were up-regulated. ETEC exposed to alkaline environments express a specific proteome profile characterized by up-regulation of membrane proteins and secretion of LT toxin. Alkaline microenvironments have been reported close to the intestinal epithelium and the alkaline proteome may hence represent a better view of ETEC during infection.

Maternal emotion socialization differentially predicts third-grade children's emotion regulation and lability.

PubMed

Rogers, Megan L; Halberstadt, Amy G; Castro, Vanessa L; MacCormack, Jennifer K; Garrett-Peters, Patricia

2016-03-01

Numerous parental emotion socialization factors have been implicated as direct and indirect contributors to the development of children's emotional competence. To date, however, no study has combined parents' emotion-related beliefs, behaviors, and regulation strategies in one model to assess their cumulative-as well as unique-contributions to children's emotion regulation. We considered the 2 components that have recently been distinguished: emotion regulation and emotional lability. We predicted that mothers' beliefs about the value of and contempt for children's emotions, mothers' supportive and nonsupportive reactions to their children's emotions, as well as mothers' use of cognitive reappraisal and suppression of their own emotions would each contribute unique variance to their children's emotion regulation and lability, as assessed by children's teachers. The study sample consisted of an ethnically and socioeconomically diverse group of 165 mothers and their third-grade children. Different patterns emerged for regulation and lability: Controlling for family income, child gender, and ethnicity, only mothers' lack of suppression as a regulatory strategy predicted greater emotion regulation in children, whereas mothers' valuing of children's emotions, mothers' lack of contempt for children's emotions, mothers' use of cognitive reappraisal to reinterpret events, and mothers' lack of emotional suppression predicted less lability in children. These findings support the divergence of emotion regulation and lability as constructs and indicate that, during middle childhood, children's lability may be substantially and uniquely affected by multiple forms of parental socialization. (c) 2016 APA, all rights reserved).

Piglet colibacillosis diagnosis based on multiplex polymerase chain reaction and immunohistochemistry of paraffin-embedded tissues

PubMed Central

de Andrade, Caroline P.; Machado, Verônica S. L.; Bianchi, Matheus V.; Rolim, Veronica M.; Cruz, Raquel A. S.; Driemeier, David

2018-01-01

Enterotoxigenic Escherichia coli (ETEC) causes diarrhea in pigs, referred to as colibacillosis. The aim of this study was to optimize multiplex polymerase chain reaction (PCR) and immunohistochemistry (IHC) analyses of paraffin-embedded material to detect pathogenic E. coli strains causing colibacillosis in pigs. Multiplex PCR was optimized for fimbriae (F18, F4, F6, F5, and F41) and toxins (types A and B heat-stable toxins [STaP and STb], heat-labile toxin [LT], and type 2 Shiga toxin [STx2e]), and IHC was optimized for an anti-E. coli polyclonal antibody. Samples (132) from pigs received between 2006 and 2014 with clinical and histopathological diagnoses of colibacillosis were analyzed. E. coli was detected by IHC in 78.7%, and at least one virulence factor gene was detected in 71.2%. Pathogenic strains of ETEC with at least one fimbria and one toxin were detected in 40% of the samples in multiplex PCR. The most frequent virulence types were F18-STaP (7.5%), F18-STaP-STb (5.7%), and F4-STaP (3.8%). A statistically significant association was noted between virulence factors F4, F18, STaP, and STb and positive immunostaining results. Colibacillosis diagnosis through multiplex PCR and IHC of paraffin-embedded tissues is a practical approach, as samples can be fixed and stored for long periods before analysis. PMID:28693311

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

Ultrafast carrier dynamics in LT-GaAs doped with Si delta layers

NASA Astrophysics Data System (ADS)

Khusyainov, D. I.; Dekeyser, C.; Buryakov, A. M.; Mishina, E. D.; Galiev, G. B.; Klimov, E. A.; Pushkarev, S. S.; Klochkov, A. N.

2017-10-01

We characterized the ultrafast properties of LT-GaAs doped with silicon δ-layers and introduced delta-doping (δ-doping) as efficient method for enhancing the properties of GaAs-based structures which can be useful for terahertz (THz) antenna, ultrafast switches and other high frequency applications. Low temperature grown GaAs (LT-GaAs) became one of the most promising materials for ultrafast optical and THz devices due to its short carrier lifetime and high carrier mobility. Low temperature growth leads to a large number of point defects and an excess of arsenic. Annealing of LT-GaAs creates high resistivity through the formation of As-clusters, which appear due to the excess of arsenic. High resistivity is very important for THz antennas so that voltage can be applied without the risk of breakdown. With δ-Si doping, control of As-clusters is possible, since after annealing, clusters align in the plane where the δ-doping occurs. In this paper, we compare the properties of LT-GaAs-based planar structures with and without δ-Si doping and subsequent annealing. We used pump-probe transient reflectivity as a probe for ultrafast carrier dynamics in LT-GaAs. The results of the experiment were interpreted using the Ortiz model and show that the δ-Si doping increases deep donor and acceptor concentrations and decreases the photoinduced carrier lifetime as compared with LT-GaAs with same growth and annealing temperatures, but without doping.

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

PubMed

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

2003-05-01

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. Currently, variants of the sequential extraction procedure developed by M. J. Hedley and co-workers afford the greatest discrimination among labile and non-labile organic and inorganic P pools. Results of recent studies that used this technique to evaluate P fractions in forest soils indicate the following: (1) in intact, highly weathered forest soils of the humid tropics, Hedley-labile P values are several times larger than extractable P values resulting from mildly acidic extracting solutions which were commonly used in the past 2 decades; (2) pools of Hedley-labile P are several times larger than the annual forest P requirement and P required from the soil annually in both temperate and tropical forests; (3) long-term trends in non-labile P pools during pedogenesis are adequately represented by the Walker and Syers' model of changes in P fractionation during soil development. However, to better represent trends in pools that can supply plant-available P across forest soils of different age and weathering status, the paradigm should be modified; and (4) across a wide range of tropical and temperate forest soils, organic matter content is an important determinant of Hedley-labile P.

Effects of labile carbon addition on a headwater stream food web

Treesearch

Heidi S. Wilcox; J. Bruce Wallace; Judy L. Meyer; Jonathan P. Benstead

2005-01-01

We added dextrose for two 8-week periods (summer and autumn) to a highly heterotrophic headwater stream in North Carolina, U.S.A., to examine the responses of its benthic food web to increased labile carbon. We hypothesized that addition of labile carbon would elevate microbial abundance and activity, resulting in greater resource availability and higher...

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

The five-factor model of impulsivity-like traits and emotional lability in aggressive behavior.

PubMed

Dvorak, Robert D; Pearson, Matthew R; Kuvaas, Nicholas J

2013-01-01

Factors that increase automatic psychological processes may result in impulsive action and, consequently, aggressive behavior. The current cross-sectional study examined the association between the five-factor model of impulsivity-like traits (negative urgency, positive urgency, premeditation, perseverance, and sensation seeking), emotional lability, and physically aggressive behaviors among college students (n = 481) in a negative binomial hurdle model. In the logistic portion of the model, emotional lability was related to a higher likelihood of engaging in aggressive acts in the past 6 months. The association between emotional lability and the likelihood of aggressive behavior was moderated by two impulsivity-like traits: negative urgency and positive urgency. Specifically, emotional lability was related to engaging in aggressive acts among those with high negative urgency, and among those with low positive urgency. In the count portion of the model, emotional lability was uniquely related to the number of aggressive acts in the past 6 months. Our results indicate that emotional lability and facets of impulsivity interactively relate to engagement in aggressive behavior, suggesting that these variables be integrated into models of aggression. © 2013 Wiley Periodicals, Inc.

Epsilon toxin: a fascinating pore-forming toxin.

PubMed

Popoff, Michel R

2011-12-01

Epsilon toxin (ETX) is produced by strains of Clostridium perfringens classified as type B or type D. ETX belongs to the heptameric β-pore-forming toxins including aerolysin and Clostridium septicum alpha toxin, which are characterized by the formation of a pore through the plasma membrane of eukaryotic cells consisting in a β-barrel of 14 amphipatic β strands. By contrast to aerolysin and C. septicum alpha toxin, ETX is a much more potent toxin and is responsible for enterotoxemia in animals, mainly sheep. ETX induces perivascular edema in various tissues and accumulates in particular in the kidneys and brain, where it causes edema and necrotic lesions. ETX is able to pass through the blood-brain barrier and stimulate the release of glutamate, which accounts for the symptoms of nervous excitation observed in animal enterotoxemia. At the cellular level, ETX causes rapid swelling followed by cell death involving necrosis. The precise mode of action of ETX remains to be determined. ETX is a powerful toxin, however, it also represents a unique tool with which to vehicle drugs into the central nervous system or target glutamatergic neurons. © 2011 The Author Journal compilation © 2011 FEBS.

Stool C difficile toxin

MedlinePlus

... toxin; Colitis - toxin; Pseudomembranous - toxin; Necrotizing colitis - toxin; C difficile - toxin ... be analyzed. There are several ways to detect C difficile toxin in the stool sample. Enzyme immunoassay ( ...

Quantification of Labile Soil Mercury by Stable Isotope Dilution Techniques

NASA Astrophysics Data System (ADS)

Shetaya, Waleed; Huang, Jen-How; Osterwalder, Stefan; Alewell, Christine

2016-04-01

Mercury (Hg) is a toxic element that can cause severe health problems to humans. Mercury is emitted to the atmosphere from both natural and anthropogenic sources and can be transported over long distances before it is deposited to aquatic and terrestrial environments. Aside from accumulation in soil solid phases, Hg deposited in soils may migrate to surface- and ground-water or enter the food chain, depending on its lability. There are many operationally-defined extraction methods proposed to quantify soil labile metals. However, these methods are by definition prone to inaccuracies such as non-selectivity, underestimation or overestimation of the labile metal pool. The isotopic dilution technique (ID) is currently the most promising method for discrimination between labile and non-labile metal fractions in soil with a minimum disturbance to soil-solid phases. ID assesses the reactive metal pool in soil by defining the fraction of metal both in solid and solution phases that is isotopically-exchangeable known as the 'E-value'. The 'E-value' represents the metal fraction in a dynamic equilibrium with the solution phase and is potentially accessible to plants. This is carried out by addition of an enriched metal isotope to soil suspensions and quantifying the fraction of metal that is able to freely exchange with the added isotope by measuring the equilibrium isotopic ratio by ICP-MS. E-value (mg kg-1) is then calculated as follows: E-Value = (Msoil/ W) (CspikeVspike/ Mspike) (Iso1IAspike -Iso2IAspikeRss / Iso2IAsoil Rss - Iso1IAsoil) where M is the average atomic mass of the metal in the soil or the spike, W is the mass of soil (kg), Cspike is the concentration of the metal in the spike (mg L-1), Vspike is the volume of spike (L), IA is isotopic abundance, and Rss is the equilibrium ratio of isotopic abundances (Iso1:Iso2). Isotopic dilution has been successfully applied to determine E-values for several elements. However, to our knowledge, this method has not yet

Affect lability predicts occurrence of suicidal ideation in bipolar patients: a two-year prospective study.

PubMed

Ducasse, D; Jaussent, I; Guillaume, S; Azorin, J M; Bellivier, F; Belzeaux, R; Bougerol, T; Etain, B; Gard, S; Henry, C; Kahn, J P; Leboyer, M; Loftus, J; Passerieux, C; Olié, E; Courtet, P

2017-05-01

The aim of our study was to investigate, in bipolar patients, whether affect lability was associated with suicidal ideation incidence during 2-year follow-up, and which subtype of affect lability was associated with suicidal ideation. A total of 319 euthymic or mildly depressed bipolar outpatients recruited in the French FondaMental Advanced Centres of Expertise for Bipolar Disorder were divided into two subgroups according to the occurrence of suicidal ideation during a 2-year follow-up. Affect lability was assessed by the French version of the Affect Lability Scale. Bipolar patients with high affect lability were more likely to report suicidal ideation during follow-up, even after adjustment for age, study level, rapid cycling, current depression level, anxiety disorder, and lifetime history SA (OR = 2.47; 95% CI [1.15-5.30], P = 0.01). The risk of suicidal ideation increased with the level of affect lability. More specifically, the propensity to switch from neutral to elation affect, from anxious to depressive affect (or inversely), and from neutral to anger affect predicted suicidal ideation. Reducing affective lability could become a new therapeutic target of suicidal prevention in bipolar disorder. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Highly conserved type 1 pili promote enterotoxigenic E. coli pathogen-host interactions

PubMed Central

Rashu, Rasheduzzaman; Begum, Yasmin Ara; Ciorba, Matthew A.; Hultgren, Scott J.; Qadri, Firdausi

2017-01-01

Enterotoxigenic Escherichia coli (ETEC), defined by their elaboration of heat-labile (LT) and/or heat-stable (ST) enterotoxins, are a common cause of diarrheal illness in developing countries. Efficient delivery of these toxins requires ETEC to engage target host enterocytes. This engagement is accomplished using a variety of pathovar-specific and conserved E. coli adhesin molecules as well as plasmid encoded colonization factors. Some of these adhesins undergo significant transcriptional modulation as ETEC encounter intestinal epithelia, perhaps suggesting that they cooperatively facilitate interaction with the host. Among genes significantly upregulated on cell contact are those encoding type 1 pili. We therefore investigated the role played by these pili in facilitating ETEC adhesion, and toxin delivery to model intestinal epithelia. We demonstrate that type 1 pili, encoded in the E. coli core genome, play an essential role in ETEC virulence, acting in concert with plasmid-encoded pathovar specific colonization factor (CF) fimbriae to promote optimal bacterial adhesion to cultured intestinal epithelium (CIE) and to epithelial monolayers differentiated from human small intestinal stem cells. Type 1 pili are tipped with the FimH adhesin which recognizes mannose with stereochemical specificity. Thus, enhanced production of highly mannosylated proteins on intestinal epithelia promoted FimH-mediated ETEC adhesion, while conversely, interruption of FimH lectin-epithelial interactions with soluble mannose, anti-FimH antibodies or mutagenesis of fimH effectively blocked ETEC adhesion. Moreover, fimH mutants were significantly impaired in delivery of both heat-stable and heat-labile toxins to the target epithelial cells in vitro, and these mutants were substantially less virulent in rabbit ileal loop assays, a classical model of ETEC pathogenesis. Collectively, our data suggest that these highly conserved pili play an essential role in virulence of these diverse

Non-labile Soil 15Nitrogen Retention beneath Three Tree Species in a Tropical Plantation

Treesearch

Jason P. Kaye; Dan Binkley; Xiaoming Zou

2002-01-01

Soil organic matter is the largest sink for N additions to forests.Species composition may affect soilNretention by altering the amount or proportion of added N stored in non-labile organic pools. We measured 15N tracer retention in labile and non-labile pools of surface (0–20 cm) mineral soils, 7 yr after the tracer was applied to a 9 yr-old Puerto Rican tree...

A SEARCH FOR L/T TRANSITION DWARFS WITH PAN-STARRS1 AND WISE. II. L/T TRANSITION ATMOSPHERES AND YOUNG DISCOVERIES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Best, William M. J.; Liu, Michael C.; Magnier, Eugene A.

The evolution of brown dwarfs from L to T spectral types is one of the least understood aspects of the ultracool population, partly for lack of a large, well-defined, and well-characterized sample in the L/T transition. To improve the existing census, we have searched ≈28,000 deg{sup 2} using the Pan-STARRS1 and Wide-field Infrared Survey Explorer surveys for L/T transition dwarfs within 25 pc. We present 130 ultracool dwarf discoveries with estimated distances ≈9–130 pc, including 21 that were independently discovered by other authors and 3 that were previously identified as photometric candidates. Seventy-nine of our objects have near-IR spectral types ofmore » L6–T4.5, the most L/T transition dwarfs from any search to date, and we have increased the census of L9–T1.5 objects within 25 pc by over 50%. The color distribution of our discoveries provides further evidence for the “L/T gap,” a deficit of objects with (J − K){sub MKO} ≈ 0.0–0.5 mag in the L/T transition, and thus reinforces the idea that the transition from cloudy to clear photospheres occurs rapidly. Among our discoveries are 31 candidate binaries based on their low-resolution spectral features. Two of these candidates are common proper motion companions to nearby main sequence stars; if confirmed as binaries, these would be rare benchmark systems with the potential to stringently test ultracool evolutionary models. Our search also serendipitously identified 23 late-M and L dwarfs with spectroscopic signs of low gravity implying youth, including 10 with vl-g or int-g gravity classifications and another 13 with indications of low gravity whose spectral types or modest spectral signal-to-noise ratio do not allow us to assign formal classifications. Finally, we identify 10 candidate members of nearby young moving groups (YMG) with spectral types L7–T4.5, including three showing spectroscopic signs of low gravity. If confirmed, any of these would be among the coolest known YMG

Radiation-induced heat-labile sites that convert into DNA double-strand breaks

NASA Technical Reports Server (NTRS)

Rydberg, B.; Chatterjee, A. (Principal Investigator)

2000-01-01

The yield of DNA double-strand breaks (DSBs) in SV40 DNA irradiated in aqueous solution was found to increase by more than a factor of two as a result of postirradiation incubation of the DNA at 50 degrees C and pH 8.0 for 24 h. This is in agreement with data from studies performed at 37 degrees C that were published previously. Importantly, similar results were also obtained from irradiation of mammalian DNA in agarose plugs. These results suggest that heat-labile sites within locally multiply damaged sites are produced by radiation and are subsequently transformed into DSBs. Since incubation at 50 degrees C is typically employed for lysis of cells in commonly used pulsed-field gel assays for detection of DSBs in mammalian cells, the possibility that heat-labile sites are present in irradiated cells was also studied. An increase in the apparent number of DSBs as a function of lysis time at 50 degrees C was found with kinetics that was similar to that for irradiated DNA, although the magnitude of the increase was smaller. This suggests that heat-labile sites are also formed in the cell. If this is the case, a proportion of DSBs measured by the pulsed-field gel assays may occur during the lysis step and may not be present in the cell as breaks but as heat-labile sites. It is suggested that such sites consist mainly of heat-labile sugar lesions within locally multiply damaged sites. Comparing rejoining of DSBs measured with short and long lysis procedure indicates that the heat-labile sites are repaired with fast kinetics in comparison with repair of the bulk of DSBs.

In Situ, High-Resolution Profiles of Labile Metals in Sediments of Lake Taihu

PubMed Central

Wang, Dan; Gong, Mengdan; Li, Yangyang; Xu, Lv; Wang, Yan; Jing, Rui; Ding, Shiming; Zhang, Chaosheng

2016-01-01

Characterizing labile metal distribution and biogeochemical behavior in sediments is crucial for understanding their contamination characteristics in lakes, for which in situ, high-resolution data is scare. The diffusive gradient in thin films (DGT) technique was used in-situ at five sites across Lake Taihu in the Yangtze River delta in China to characterize the distribution and mobility of eight labile metals (Fe, Mn, Zn, Ni, Cu, Pb, Co and Cd) in sediments at a 3 mm spatial resolution. The results showed a great spatial heterogeneity in the distributions of redox-sensitive labile Fe, Mn and Co in sediments, while other metals had much less marked structure, except for downward decreases of labile Pb, Ni, Zn and Cu in the surface sediment layers. Similar distributions were found between labile Mn and Co and among labile Ni, Cu and Zn, reflecting a close link between their geochemical behaviors. The relative mobility, defined as the ratio of metals accumulated by DGT to the total contents in a volume of sediments with a thickness of 10 mm close to the surface of DGT probe, was the greatest for Mn and Cd, followed by Zn, Ni, Cu and Co, while Pb and Fe had the lowest mobility; this order generally agreed with that defined by the modified BCR approach. Further analyses showed that the downward increases of pH values in surface sediment layer may decrease the lability of Pb, Ni, Zn and Cu as detected by DGT, while the remobilization of redox-insensitive metals in deep sediment layer may relate to Mn cycling through sulphide coprecipitation, reflected by several corresponding minima between these metals and Mn. These in situ data provided the possibility for a deep insight into the mechanisms involved in the remobilization of metals in freshwater sediments. PMID:27608033

Antibacterial and Antidiarrheal Activities of Plant Products against Enterotoxinogenic Escherichia coli

PubMed Central

Dubreuil, J. Daniel

2013-01-01

Enterotoxigenic Escherichia coli (ETEC) produces two types of enterotoxins: heat-labile (LT) and heat-stable (STa and STb). These molecules are involved in the induction of secretory diarrhea in animals including humans. This condition is currently treated using a fluid replacement therapy and antibiotics. This treatment is often not available to people in developing countries, and several die from the condition provoke by ETEC. Over the years, plants and plant extracts have been use as traditional medicine to treat various gastrointestinal ailments including diarrhea. Many of these plant products have been claimed to be active against diarrhea, however few have been extensively studied. The main objective of this review was to gather the scattered information on the antidiarrheal activities reported for various plant products on ETEC. This includes two major effects: (1) The inhibitory effect on bacterial growth or viability and (2) The interference with ETEC enterotoxins activity upon the intestinal epithelium. We will focus on plant products and extracts for which we have major indications of their biological activity against ETEC and their enterotoxins. Because Vibrio cholerae toxin (CT) is structurally, antigenically and mechanistically related to LT, it will also be discussed in this review. PMID:24212181

Phaeochromocytoma presenting with labile blood pressures following coronary artery bypass grafting.

PubMed

Roy, James; Akhunji, Zakir; Kushwaha, Virag; Mackie, James; Jepson, Nigel

2016-12-01

Pheochromocytomas have been reported prior to and during coronary artery bypass surgery. We present a patient with an undiagnosed pheochromocytoma who presented with labile hypertension following coronary artery bypass surgery. This case calls attention to the inclusion of an undiagnosed pheochromocytoma in the differential diagnosis for all patients who develop labile hypertension in the postoperative period following cardiac surgery. © 2016 Wiley Periodicals, Inc.

Mechanism of Stabilization of Labile Compounds by Silk Fibroin Proteins

DTIC Science & Technology

2017-04-05

AFRL-AFOSR-VA-TR-2017-0076 Mechanism of Stabilization of Labile Compounds by Silk Fibroin Proteins David Kaplan TRUSTEES OF TUFTS COLEGE INC 169... Proteins 5a.  CONTRACT NUMBER 5b.  GRANT NUMBER FA9550-14-1-0015 5c.  PROGRAM ELEMENT NUMBER 61102F 6. AUTHOR(S) David Kaplan 5d.  PROJECT NUMBER 5e...objective of this research was to elucidate the fundamental mechanisms by which labile compounds are entrapped and stabilized by silk fibroin protein . The

Simulation-Based e-Learning Tools for Science,Engineering, and Technology Education(SimBeLT)

NASA Astrophysics Data System (ADS)

Davis, Doyle V.; Cherner, Y.

2006-12-01

The focus of Project SimBeLT is the research, development, testing, and dissemination of a new type of simulation-based integrated e-learning set of modules for two-year college technical and engineering curricula in the areas of thermodynamics, fluid physics, and fiber optics that can also be used in secondary schools and four-year colleges. A collection of sophisticated virtual labs is the core component of the SimBeLT modules. These labs will be designed to enhance the understanding of technical concepts and underlying fundamental principles of these topics, as well as to master certain performance based skills online. SimBeLT software will help educators to meet the National Science Education Standard that "learning science and technology is something that students do, not something that is done to them". A major component of Project SimBeLT is the development of multi-layered technology-oriented virtual labs that realistically mimic workplace-like environments. Dynamic data exchange between simulations will be implemented and links with instant instructional messages and data handling tools will be realized. A second important goal of Project SimBeLT labs is to bridge technical skills and scientific knowledge by enhancing the teaching and learning of specific scientific or engineering subjects. SimBeLT builds upon research and outcomes of interactive teaching strategies and tools developed through prior NSF funding (http://webphysics.nhctc.edu/compact/index.html) (Project SimBeLT is partially supported by a grant from the National Science Foundation DUE-0603277)

How to Compute Labile Metal-Ligand Equilibria

ERIC Educational Resources Information Center

de Levie, Robert

2007-01-01

The different methods used for computing labile metal-ligand complexes, which are suitable for an iterative computer solution, are illustrated. The ligand function has allowed students to relegate otherwise tedious iterations to a computer, while retaining complete control over what is calculated.

Inhibition of cholera toxin and other AB toxins by polyphenolic compounds

USDA-ARS?s Scientific Manuscript database

All AB-type protein toxins have intracellular targets despite an initial extracellular location. These toxins use different methods to reach the cytosol and have different effects on the target cell. Broad-spectrum inhibitors against AB toxins are therefore hard to develop because the toxins use dif...

Effect of exogenous phosphate on the lability and phytoavailability of arsenic in soils.

PubMed

Wang, Jinjin; Zeng, Xibai; Zhang, Hao; Li, Yongtao; Zhao, Shizhen; Su, Shiming; Bai, Lingyu; Wang, Yanan; Zhang, Tuo

2018-04-01

The effect of exogenous phosphate (P, 200 mg⋅kg -1 soil) on the lability and phytoavailability of arsenic (As) was studied using the diffusive gradients in thin films (DGT) technique. Lettuce were grown on the As-amended soils following the stabilization of soil labile As after 90 days incubation. Phosphate (P) application generally facilitated plant growth except one grown on P-sufficient soil. Soil labile As concentration increased in all the soils after P application due to a competition effect. Plant As concentration increased in red soils collected from Hunan Province, while decreases were observed in the other soils. Even though, an overall trend of decrease was obtained in As phytoavailability along with the increase of DGT-measured soil labile P/As molar ratio. The functional equation between P/As and As phytoavailability provided a critical value of 1.7, which could be used as a guidance for rational P fertilization, thus avoiding overfertilization. Copyright © 2018 Elsevier Ltd. All rights reserved.

Binding of ATP by pertussis toxin and isolated toxin subunits

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hausman, S.Z.; Manclark, C.R.; Burns, D.L.

1990-07-03

The binding of ATP to pertussis toxin and its components, the A subunit and B oligomer, was investigated. Whereas, radiolabeled ATP bound to the B oligomer and pertussis toxin, no binding to the A subunit was observed. The binding of ({sup 3}H)ATP to pertussis toxin and the B oligomer was inhibited by nucleotides. The relative effectiveness of the nucleotides was shown to be ATP > GTP > CTP > TTP for pertussis toxin and ATP > GTP > TTP > CTP for the B oligomer. Phosphate ions inhibited the binding of ({sup 3}H)ATP to pertussis toxin in a competitive manner;more » however, the presence of phosphate ions was essential for binding of ATP to the B oligomer. The toxin substrate, NAD, did not affect the binding of ({sup 3}H)ATP to pertussis toxin, although the glycoprotein fetuin significantly decreased binding. These results suggest that the binding site for ATP is located on the B oligomer and is distinct from the enzymatically active site but may be located near the eukaryotic receptor binding site.« less

Using isotopic dilution to assess chemical extraction of labile Ni, Cu, Zn, Cd and Pb in soils.

PubMed

Garforth, J M; Bailey, E H; Tye, A M; Young, S D; Lofts, S

2016-07-01

Chemical extractants used to measure labile soil metal must ideally select for and solubilise the labile fraction, with minimal solubilisation of non-labile metal. We assessed four extractants (0.43 M HNO3, 0.43 M CH3COOH, 0.05 M Na2H2EDTA and 1 M CaCl2) against these requirements. For soils contaminated by contrasting sources, we compared isotopically exchangeable Ni, Cu, Zn, Cd and Pb (EValue, mg kg(-1)), with the concentrations of metal solubilised by the chemical extractants (MExt, mg kg(-1)). Crucially, we also determined isotopically exchangeable metal in the soil-extractant systems (EExt, mg kg(-1)). Thus 'EExt - EValue' quantifies the concentration of mobilised non-labile metal, while 'EExt - MExt' represents adsorbed labile metal in the presence of the extractant. Extraction with CaCl2 consistently underestimated EValue for Ni, Cu, Zn and Pb, while providing a reasonable estimate of EValue for Cd. In contrast, extraction with HNO3 both consistently mobilised non-labile metal and overestimated the EValue. Extraction with CH3COOH appeared to provide a good estimate of EValue for Cd; however, this was the net outcome of incomplete solubilisation of labile metal, and concurrent mobilisation of non-labile metal by the extractant (MExtEValue). The Na2H2EDTA extractant mobilised some non-labile metal in three of the four soils, but consistently solubilised the entire labile fraction for all soil-metal combinations (MExt ≈ EExt). Comparison of EValue, MExt and EExt provides a rigorous means of assessing the underlying action of soil chemical extraction methods and could be used to refine long-standing soil extraction methodologies. Copyright © 2016 Elsevier Ltd. All rights reserved.

Impact of System-Wide King LT Airway Implementation on Orotracheal Intubation.

PubMed

Hilton, Michael T; Wayne, Max; Martin-Gill, Christian

2016-01-01

Orotracheal intubation is a key component of prehospital airway management and success rates are dependent on procedural experience. Supraglottic airway devices are increasingly being used in the prehospital setting. As a result, paramedics may have fewer opportunities for performing intubation, limiting their proficiency in the procedure. We aimed to determine the trends in intubation versus supraglottic airway use over an 8 year period. We also aimed to determine the association between system-wide introduction of King LT guidelines and ETI success rates. We performed a retrospective observational study of 37 Emergency Medical Services (EMS) agencies in a 10 county region of Southwestern Pennsylvania. Cases between January 1, 2005 and December 31, 2012 were included if an advanced airway procedure was performed. We determined trends in advanced airway placement and compared the proportion of cases with first pass intubation success before and after the King LT was introduced and promoted by statewide protocol starting in 2007. Use of airway devices before and after King LT implementation were presented using descriptive statistics and compared using Pearson's Chi-square or Fishers Exact test as appropriate. We compared first pass success rate of orotracheal intubation between study periods using multivariable logistic regression, controlling for other factors that may impact success of orotracheal intubation (year, EMS agency, age category, traumatic injury, and cardiac arrest). There were 712 cases of orotracheal intubation before and 2,835 cases after introduction of the King LT. The proportion of cases ultimately managed with orotracheal intubation before and after 2007 decreased from 72.3% (95% CI 68.9-75.6%) to 67.1% (95% CI 65.3-68.8%) (p = 0.007). In the multivariable analysis, success of orotracheal intubation was not associated with implementation of the King LT airway (OR 1.02, 95% CI 0.74-1.41). Fewer patients with advanced airway management received

Low temperature solid oxide electrolytes (LT-SOE): A review

NASA Astrophysics Data System (ADS)

Singh, B.; Ghosh, S.; Aich, S.; Roy, B.

2017-01-01

Low temperature solid oxide fuel cell (LT-SOFC) can be a source of power for vehicles, online grid, and at the same time reduce system cost, offer high reliability, and fast start-up. A huge amount of research work, as evident from the literature has been conducted for the enhancement of the ionic conductivity of LT electrolytes in the last few years. The basic conduction mechanisms, advantages and disadvantages of different LT oxide ion conducting electrolytes {BIMEVOX systems, bilayer systems including doped cerium oxide/stabilised bismuth oxide and YSZ/DCO}, mixed ion conducting electrolytes {doped cerium oxides/alkali metal carbonate composites}, and proton conducting electrolytes {doped and undoped BaCeO3, BaZrO3, etc.} are discussed here based on the recent research articles. Effect of various material aspects (composition, doping, layer thickness, etc.), fabrication methods (to achieve different microstructures and particle size), design related strategies (interlayer, sintering aid etc.), characterization temperature & environment on the conductivity of the electrolytes and performance of the fuel cells made from these electrolytes are shown in tabular form and discussed. The conductivity of the electrolytes and performance of the corresponding fuel cells are compared. Other applications of the electrolytes are mentioned. A few considerations regarding the future prospects are pointed.

Quantification and characterization of chemically-and thermally-labile and recalcitrant biochar fractions.

PubMed

Bakshi, Santanu; Banik, Chumki; Laird, David A

2018-03-01

The C:N ratios of biochar labile fractions is important for assessing biochar stability and N cycling in soil. Here we compare chemically and thermally labile fractions for nine biochars produced from five biomass feedstocks using four production techniques. Biochar fractionation methods included proximate analysis, hot water extraction, acid and base extractions (0.05 M, 0.5 M, 1 M, 2 M, 3 M, and 6 M of either H 2 SO 4 or NaOH), and oxidation with 15% H 2 O 2 and 0.33 M KMnO 4 (pH 7.2). Results show chemical addition reactions cause underestimation of mass of the labile fraction for chemical extraction and oxidation procedures but not the thermal procedure. Estimates of C and N in labile and recalcitrant fractions were not adversely affected by addition reactions, because solvents were independent of C or N. Results indicate that herbaceous biochars may be a source of N fertility while hardwood biochars may immobilize N during the first few years after biochar application to soils. Copyright © 2017 Elsevier Ltd. All rights reserved.

Failure of botulinum toxin injection for neurogenic detrusor overactivity: Switch of toxin versus second injection of the same toxin.

PubMed

Peyronnet, Benoit; Castel-Lacanal, Evelyne; Manunta, Andréa; Roumiguié, Mathieu; Marque, Philippe; Rischmann, Pascal; Gamé, Xavier

2015-12-01

To evaluate the efficacy of a second injection of the same toxin versus switching to a different botulinum toxin A after failure of a first detrusor injection in patients with neurogenic detrusor overactivity. The charts of all patients who underwent detrusor injections of botulinum toxin A (either abobotulinumtoxinA or onabotulinumtoxinA) for the management of neurogenic detrusor overactivity at a single institution were retrospectively reviewed. Patients in whom a first detrusor injection had failed were included in the present study. They were managed by a second injection of the same toxin at the same dosage or by a new detrusor injection using a different botulinum toxin A. Success was defined as a resolution of urgency, urinary incontinence and detrusor overactivity in a patient self-catheterizing seven times or less per 24 h. A total of 58 patients were included for analysis. A toxin switch was carried out in 29 patients, whereas the other 29 patients received a reinjection of the same toxin at the same dose. The success rate was higher in patients who received a toxin switch (51.7% vs. 24.1%, P = 0.03). Patients treated with a switch from abobotulinumtoxinA to onabotulinumtoxinA and those treated with a switch from onabotulinumtoxinA to abobotulinumtoxinA had similar success rates (52.9% vs. 50%, P = 0.88). After failure of a first detrusor injection of botulinum toxin for neurogenic detrusor overactivity, a switch to a different toxin seems to be more effective than a second injection of the same toxin. The replacement of onabotulinumtoxin by abobotulinumtoxin or the reverse provides similar results. © 2015 The Japanese Urological Association.

CysLT2 receptor activation is involved in LTC4-induced lung air-trapping in guinea pigs.

PubMed

Sekioka, Tomohiko; Kadode, Michiaki; Yonetomi, Yasuo; Kamiya, Akihiro; Fujita, Manabu; Nabe, Takeshi; Kawabata, Kazuhito

2017-01-05

CysLT 1 receptors are known to be involved in the pathogenesis of asthma. However, the functional roles of CysLT 2 receptors in this condition have not been determined. The purpose of this study is to develop an experimental model of CysLT 2 receptor-mediated LTC 4 -induced lung air-trapping in guinea pigs and use this model to clarify the mechanism underlying response to such trapping. Because LTC 4 is rapidly converted to LTD 4 by γ-glutamyltranspeptidase (γ-GTP) under physiological conditions, S-hexyl GSH was used as a γ-GTP inhibitor. In anesthetized artificially ventilated guinea pigs with no S-hexyl GSH treatment, i.v. LTC 4 -induced bronchoconstriction was almost completely inhibited by montelukast, a CysLT 1 receptor antagonist, but not by BayCysLT 2 RA, a CysLT 2 receptor antagonist. The inhibitory effect of montelukast was diminished by treatment with S-hexyl GSH, whereas the effect of BayCysLT 2 RA was enhanced with increasing dose of S-hexyl GSH. Macroscopic and histological examination of lung tissue isolated from LTC 4 -/S-hexyl-GSH-treated guinea pigs revealed air-trapping expansion, particularly at the alveolar site. Inhaled LTC 4 in conscious guinea pigs treated with S-hexyl GSH increased both airway resistance and airway hyperinflation. On the other hand, LTC 4 -induced air-trapping was only partially suppressed by treatment with the bronchodilator salmeterol. Although montelukast inhibition of LTC 4 -induced air-trapping was weak, treatment with BayCysLT 2 RA resulted in complete suppression of this air-trapping. Furthermore, BayCysLT 2 RA completely suppressed LTC 4 -induced airway vascular hyperpermeability. In conclusion, we found in this study that CysLT 2 receptors mediate LTC 4 -induced bronchoconstriction and air-trapping in S-hexyl GSH-treated guinea pigs. It is therefore believed that CysLT 2 receptors contribute to asthmatic response involving air-trapping. Copyright © 2016 Elsevier B.V. All rights reserved.

Modeling Effects of Lability on Microbial Uptake of DOM in River Reaches

NASA Astrophysics Data System (ADS)

Li, A.; Drummond, J. D.; Bowen, J. C.; Cory, R. M.; Kaplan, L.; Packman, A. I.

2017-12-01

Rivers are hotspots for biological degradation of dissolved organic matter (DOM), contributing to 1.8 petagrams of carbon emissions per year. DOM represents approximately 60% of the total mass of organic carbon transported within river networks, fueling stream ecosystem metabolism. Not all DOM is biodegradable, biodegradation rates vary based on lability, and lability decreases with reaction time. Fluorescent fractions of DOM (FDOM) are often used as proxies of DOM lability. Humic-like FDOM, previously considered recalcitrant and thought to contribute minimally to the biodegradable DOM pools, has recently been shown to contribute more than 50% to DOM uptake in bioreactor columns colonized by bacteria in stream water. Protein-like FDOM, a proxy for the biodegradable DOM pool, also contributes to the recalcitrant DOM pool in bioreactors. However, the contribution of different lability pools to DOM uptake at the reach scale remains elusive. Here we combine local-scale results from a bioreactor study and measures of stream geomorphology parameters to model reach-scale DOM uptake in White Clay Creek, a Pennsylvania piedmont stream with an intact, forested riparian zone and inputs from upland agriculture. Steady state modeling of a point-source, continuous injection of FDOM shows that humic-like FDOM contributes up to 80% of the total removal of FDOM at the reach scale, suggesting its importance to in-stream DOM uptake. Tryptophan-like FDOM, a protein-like FDOM, contributes to 80% of the remaining fraction of FDOM at the reach scale that incorporates longer timescales of transport and retention. This is consistent with recent local-scale findings that the lability of tryptophan-like FDOM decreases substantially with reaction time in bioreactors, such that it becomes much more recalcitrant as it travels downstream. Steady state modeling of a distributed source, continuous injection of FDOM shows that contributing sources distribute differently along the river reach for

A role for inflammatory mediators in heterologous desensitization of CysLT1 receptor in human monocytes

PubMed Central

Capra, Valérie; Accomazzo, Maria Rosa; Gardoni, Fabrizio; Barbieri, Silvia; Rovati, G. Enrico

2010-01-01

Cysteinyl-leukotrienes (cysteinyl-LT) are rapidly generated at sites of inflammation and, in addition to their role in asthma, rhinitis, and other immune disorders, are increasingly regarded as significant inflammatory factors in cancer, gastrointestinal, cardiovascular diseases. We recently demonstrated that in monocyte/macrophage–like U937 cells, extracellular nucleotides heterologously desensitize CysLT1 receptor (CysLT1R)-induced Ca2+ transients. Given that monocytes express a number of other inflammatory and chemoattractant receptors, this study was aimed at characterizing transregulation between these different stimuli. We demonstrate that in U937 cells and in primary human monocytes, a series of inflammatory mediators activating Gi-coupled receptor (FPR1, BLT1) desensitize CysLT1R-induced Ca2+ response unidirectionally through activation of PKC. Conversely, PAF-R, exclusively coupled to Gq, cross-desensitizes CysLT1R without the apparent involvement of any kinase. Interestingly, Gs-coupled receptors (β2AR, H1/2R, EP2/4R) are also able to desensitize CysLT1R response through activation of PKA. Heterologous desensitization seems to affect mostly the Gi-mediated signaling of the CysLT1R. The hierarchy of desensitization among agonists may be important for leukocyte signal processing at the site of inflammation. Considering that monocytes/macrophages are likely to be the major source of cysteinyl-LT in many immunological and inflammatory processes, shedding light on how their receptors are regulated will certainly help to better understand the role of these cells in orchestrating this complex network of integrated signals. PMID:19965602

ANIMAL ENTEROTOXIGENIC ESCHERICHIA COLI

PubMed Central

Dubreuil, J. Daniel; Isaacson, Richard E.; Schifferli, Dieter M.

2016-01-01

Enterotoxigenic Escherichia coli (ETEC) is the most common cause of E. coli diarrhea in farm animals. ETEC are characterized by the ability to produce two types of virulence factors; adhesins that promote binding to specific enterocyte receptors for intestinal colonization and enterotoxins responsible for fluid secretion. The best-characterized adhesins are expressed in the context of fimbriae, such as the F4 (also designated K88), F5 (K99), F6 (987P), F17 and F18 fimbriae. Once established in the animal small intestine, ETEC produces enterotoxin(s) that lead to diarrhea. The enterotoxins belong to two major classes; heat-labile toxin that consist of one active and five binding subunits (LT), and heat-stable toxins that are small polypeptides (STa, STb, and EAST1). This chapter describes the disease and pathogenesis of animal ETEC, the corresponding virulence genes and protein products of these bacteria, their regulation and targets in animal hosts, as well as mechanisms of action. Furthermore, vaccines, inhibitors, probiotics and the identification of potential new targets identified by genomics are presented in the context of animal ETEC. PMID:27735786

Toxins, Targets, and Triggers: An Overview of Toxin-Antitoxin Biology.

PubMed

Harms, Alexander; Brodersen, Ditlev Egeskov; Mitarai, Namiko; Gerdes, Kenn

2018-06-07

Bacterial toxin-antitoxin (TA) modules are abundant genetic elements that encode a toxin protein capable of inhibiting cell growth and an antitoxin that counteracts the toxin. The majority of toxins are enzymes that interfere with translation or DNA replication, but a wide variety of molecular activities and cellular targets have been described. Antitoxins are proteins or RNAs that often control their cognate toxins through direct interactions and, in conjunction with other signaling elements, through transcriptional and translational regulation of TA module expression. Three major biological functions of TA modules have been discovered, post-segregational killing ("plasmid addiction"), abortive infection (bacteriophage immunity through altruistic suicide), and persister formation (antibiotic tolerance through dormancy). In this review, we summarize the current state of the field and highlight how multiple levels of regulation shape the conditions of toxin activation to achieve the different biological functions of TA modules. Copyright © 2018 Elsevier Inc. All rights reserved.

Toxic shock syndrome toxin-1, not α-toxin, mediated Bundaberg fatalities.

PubMed

Mueller, Elizabeth A; Merriman, Joseph A; Schlievert, Patrick M

2015-12-01

The 1928 Bundaberg disaster is one of the greatest vaccine tragedies in history. Of 21 children immunized with a diphtheria toxin-antitoxin preparation contaminated with Staphylococcus aureus, 18 developed life-threatening disease and 12 died within 48  h. Historically, the deaths have been attributed to α-toxin, a secreted cytotoxin produced by most S. aureus strains, yet the ability of the Bundaberg contaminant microbe to produce the toxin has never been verified. For the first time, the ability of the original strain to produce α-toxin and other virulence factors is investigated. The study investigates the genetic and regulatory loci mediating α-toxin expression by PCR and assesses production of the cytotoxin in vitro using an erythrocyte haemolysis assay. This analysis is extended to other secreted virulence factors produced by the strain, and their sufficiency to cause lethality in New Zealand white rabbits is determined. Although the strain possesses a wild-type allele for α-toxin, it must have a defective regulatory system, which is responsible for the strain's minimal α-toxin production. The strain encodes and produces staphylococcal superantigens, including toxic shock syndrome toxin-1 (TSST-1), which is sufficient to cause lethality in patients. The findings cast doubt on the belief that α-toxin is the major virulence factor responsible for the Bundaberg fatalities and point to the superantigen TSST-1 as the cause of the disaster.

Childhood Maltreatment, Emotional Lability, and Alcohol Problems in Young Adults At-Risk for ADHD: Testing Moderation and Moderated Moderation.

PubMed

Bunford, Nóra; Wymbs, Brian T; Dawson, Anne E; Shorey, Ryan C

2017-01-01

Childhood maltreatment and alcohol problems are common among young adults with attention-deficit hyperactivity disorder (ADHD). However, little is known about the degree to which maltreatment and alcohol problems are associated; potential pertinent mediating or moderating mechanisms, such as emotional lability; and whether this association varies by sex. We examined, in a sample of adults at risk for ADHD (N = 122, 37% male), the association between childhood maltreatment and alcohol problems, whether emotional lability mediated or moderated this association, and whether either role of emotional lability differed between men and women. Emotional lability moderated the association between emotional neglect and alcohol problems; maltreatment increased risk for alcohol problems for those scoring high tovery high on emotional lability, but not for those with very low-moderate levels. The association between emotional abuse and alcohol problems depended both on emotional lability and sex; emotional abuse decreased the risk for alcohol problems among men very low/low on emotional lability, but not for men who were moderate to very high on emotional lability, or for women. These findings have implications for the way in which targeting maltreatment and emotional lability may be incorporated into prevention and intervention programs to prevent alcohol problems among men and women at risk for ADHD.

Transcutaneous immunization with cross-reacting material CRM(197) of diphtheria toxin boosts functional antibody levels in mice primed parenterally with adsorbed diphtheria toxoid vaccine.

PubMed

Stickings, Paul; Peyre, Marisa; Coombes, Laura; Muller, Sylviane; Rappuoli, Rino; Del Giudice, Giuseppe; Partidos, Charalambos D; Sesardic, Dorothea

2008-04-01

Transcutaneous immunization (TCI) capitalizes on the accessibility and immunocompetence of the skin, elicits protective immunity, simplifies vaccine delivery, and may be particularly advantageous when frequent boosting is required. In this study we examined the potential of TCI to boost preexisting immune responses to diphtheria in mice. The cross-reacting material (CRM(197)) of diphtheria toxin was used as the boosting antigen and was administered alone or together with either one of two commonly used mucosal adjuvants, cholera toxin (CT) and a partially detoxified mutant of heat-labile enterotoxin of Escherichia coli (LTR72). We report that TCI with CRM(197) significantly boosted preexisting immune responses elicited after parenteral priming with aluminum hydroxide-adsorbed diphtheria toxoid (DTxd) vaccine. In the presence of LTR72 as an adjuvant, toxin-neutralizing antibody titers were significantly higher than those elicited by CRM(197) alone and were comparable to the functional antibody levels induced after parenteral booster immunization with the adsorbed DTxd vaccine. Time course study showed that high levels of toxin-neutralizing antibodies persisted for at least 14 weeks after the transcutaneous boost. In addition, TCI resulted in a vigorous antigen-specific proliferative response in all groups of mice boosted with the CRM(197) protein. These findings highlight the promising prospect of using booster administrations of CRM(197) via the transcutaneous route to establish good herd immunity against diphtheria.

Tetanus toxin interaction with human erythrocytes. II. Kinetic properties of toxin association and evidence for a ganglioside-toxin macromolecular complex formation.

PubMed

Lazarovici, P; Yavin, E

1985-01-25

The properties of tetanus toxin interaction with human erythrocytes supplemented with disialo- and trisialo-gangliosides have been investigated. Binding of toxin is linear with time for 1 h and is 3-4-fold higher at 37 degrees C than at 4 degrees C during incubation of long duration. It exhibits saturation at toxin concentrations between 0.1 and 1 microgram/ml; however, it is nonsaturable between 1 and up to 50 micrograms/ml. It is effectively prevented by free gangliosides and antibodies or by pretreatment with sialidase but is unaffected by a number of closely related ligands including toxoid and toxin fragments. NaCl (1 M) removes a great portion (86%) of cell-associated toxin while Triton X-100 extracts an additional fraction (30%) of the salt-resistant cell-bound toxin. The residual sequestred toxin after detergent extraction is sensitive to proteolytic degradation. The trypsin-stable fraction (1.5%) is biotoxic and may be indicative of internalization of toxin. A macromolecular complex of about 700 kDa containing toxin and gangliosides has been isolated and characterized by Sephacryl S-300 gel permeation chromatography, SDS-gel electrophoresis, immunoprecipitability and biotoxicity. This complex is obtained only in ganglioside-supplemented cells and not when free 3H-labeled GD1b is reacted with 125I-labeled toxin in solution in the absence of cells. The hydrophobicity properties acquired as a result of ganglioside-toxin interaction, presumably at the cell surface, suggest a conformational change of the toxin which may enable its penetration into the bilayer.

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

PubMed Central

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 mediator between emotion lability/negativity and internalizing symptomatology, whereas emotion lability/negativity was not a mediator between emotion regulation and internalizing symptomatology. Early maltreatment was associated with high emotion lability/negativity (age 7) that contributed to poor emotion regulation (age 8), which in turn was predictive of increases in internalizing symptomatology (from age 8 to 9). The results imply important roles of emotion regulation in the development of internalizing symptomatology, especially for children with high emotion lability/negativity. PMID:23034132

'Inconstant males' and the maintenance of labile sex expression in subdioecious plants.

PubMed

Ehlers, Bodil K; Bataillon, Thomas

2007-01-01

* Here, we evaluate the role of pollen limitation and selfing in the maintenance of labile sex expression in subdioecious plant species. * We used a literature survey to explore which factors correlated with a significant occurrence of hermaphrodites in dioecious species. We developed models to explore the selective maintenance of labile sex expression. The models had similar ecological assumptions but differed in the genetic basis of sex lability. * We found that a significant frequency of hermaphrodites was associated with animal pollination, and that hermaphrodites were 'inconstant' males with perfect flowers, suggesting evolution through the gynodioecious pathway. Models showed that a modifier converting pure males into inconstant males could be maintained under a wide range of reduction in both male and female fitness. Pollen limitation and self-fertilization facilitated invasion of the modifier. Depending on the genetics of sex determination, we found pure dioecy, stable subdioecy (trioecy), and situations where inconstant males coexisted with either pure females or pure males. Under selfing and pollen limitation, certain conditions selected for inconstant males which will drive populations to extinction. * We discuss our results in relation to the evolution towards, and the breakdown of, dioecy, and the ecological and evolutionary implications of labile sex expression.

Submillimeter-scale heterogeneity of labile phosphorus in sediments characterized by diffusive gradients in thin films and spatial analysis.

PubMed

Meng, Yuting; Ding, Shiming; Gong, Mengdan; Chen, Musong; Wang, Yan; Fan, Xianfang; Shi, Lei; Zhang, Chaosheng

2018-03-01

Sediments have a heterogeneous distribution of labile redox-sensitive elements due to a drastic downward transition from oxic to anoxic condition as a result of organic matter degradation. Characterization of the heterogeneous nature of sediments is vital for understanding of small-scale biogeochemical processes. However, there are limited reports on the related specialized methodology. In this study, the monthly distributions of labile phosphorus (P), a redox-sensitive limiting nutrient, were measured in the eutrophic Lake Taihu by Zr-oxide diffusive gradients in thin films (Zr-oxide DGT) on a two-dimensional (2D) submillimeter level. Geographical information system (GIS) techniques were used to visualize the labile P distribution at such a micro-scale, showing that the DGT-labile P was low in winter and high in summer. Spatial analysis methods, including semivariogram and Moran's I, were used to quantify the spatial variation of DGT-labile P. The distribution of DGT-labile P had clear submillimeter-scale spatial patterns with significant spatial autocorrelation during the whole year and displayed seasonal changes. High values of labile P with strong spatial variation were observed in summer, while low values of labile P with relatively uniform spatial patterns were detected in winter, demonstrating the strong influences of temperature on the mobility and spatial distribution of P in sediment profiles. Copyright © 2017 Elsevier Ltd. All rights reserved.

Advancements in the treatment of hypothyroidism with L-T4 liquid formulation or soft gel capsule: an update.

PubMed

Fallahi, Poupak; Ferrari, Silvia Martina; Ruffilli, Ilaria; Ragusa, Francesca; Biricotti, Marco; Materazzi, Gabriele; Miccoli, Paolo; Antonelli, Alessandro

2017-05-01

The most recent advance concerning levothyroxine (L-T4) therapy is the development of novel oral formulations: the liquid preparation, and the soft gel capsule. Areas covered: This review evaluates the most recent clinical studies about these new formulations. The liquid formulation has been shown to overcome: the food and beverages intereference with L-T4 tablets absorption, caused by food or coffee at breakfast; malabsorption induced by the increased gastric pH, resulting from atrophic gastritis, or due to proton-pump inhibitors; and malabsorption after bariatric surgery. The use of liquid L-T4 has been studied also in pregnancy, newborns and infants, suggesting a better bioequivalence than tablets. Finally, liquid L-T4 is more active than tablets in the control of thyroid-stimulating hormone (TSH) in hypothyroid patients without malabsorption, drug interference, or gastric disorders, leading to a hypothesized higher absorption of liquid L-T4 also in these patients. Few studies have evaluated soft gel L-T4 with promising results in patients with malabsorption related to coffee or gastritis. Expert opinion: Liquid L-T4 (and soft gel capsules) are more active than the tablet L-T4 in the control of TSH in hypothyroid patients with gastric disorders, malabsorption, or drug interference, but also in patients without absorption disorders.

Anthrax Toxin

DTIC Science & Technology

1984-10-26

focused initially on EF because it seemed possible that this component, like cholera toxin, might cause edema in skin through elevation of cellular cAMP...behavior differed from that seen in cells exposed to cholera toxin, where cellular cAMP levels remain elevated upon toxin removal. Studies in CHO cell...LF, the rat bioassay is not likely to be an appropriate system for studying the cellular and molecular mechanisms of action of LF. Therefore, a survey

Oral immunization with a recombinant bacterial antigen produced in transgenic plants.

PubMed

Haq, T A; Mason, H S; Clements, J D; Arntzen, C J

1995-05-05

The binding subunit of Escherichia coli heat-labile enterotoxin (LT-B) is a highly active oral immunogen. Transgenic tobacco and potato plants were made with the use of genes encoding LT-B or an LT-B fusion protein with a microsomal retention sequence. The plants expressed the foreign peptides, both of which formed oligomers that bound the natural ligand. Mice immunized by gavage produced serum and gut mucosal anti-LT-B immunoglobulins that neutralized the enterotoxin in cell protection assays. Feeding mice fresh transgenic potato tubers also caused oral immunization.

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.

Metabolism of HT-2 Toxin and T-2 Toxin in Oats

PubMed Central

Meng-Reiterer, Jacqueline; Bueschl, Christoph; Rechthaler, Justyna; Berthiller, Franz; Lemmens, Marc; Schuhmacher, Rainer

2016-01-01

The Fusarium mycotoxins HT-2 toxin (HT2) and T-2 toxin (T2) are frequent contaminants in oats. These toxins, but also their plant metabolites, may contribute to toxicological effects. This work describes the use of 13C-assisted liquid chromatography–high-resolution mass spectrometry for the first comprehensive study on the biotransformation of HT2 and T2 in oats. Using this approach, 16 HT2 and 17 T2 metabolites were annotated including novel glycosylated and hydroxylated forms of the toxins, hydrolysis products, and conjugates with acetic acid, putative malic acid, malonic acid, and ferulic acid. Further targeted quantitative analysis was performed to study toxin metabolism over time, as well as toxin and conjugate mobility within non-treated plant tissues. As a result, HT2-3-O-β-d-glucoside was identified as the major detoxification product of both parent toxins, which was rapidly formed (to an extent of 74% in HT2-treated and 48% in T2-treated oats within one day after treatment) and further metabolised. Mobility of the parent toxins appeared to be negligible, while HT2-3-O-β-d-glucoside was partly transported (up to approximately 4%) through panicle side branches and stem. Our findings demonstrate that the presented combination of untargeted and targeted analysis is well suited for the comprehensive elucidation of mycotoxin metabolism in plants. PMID:27929394

Lipophilic Cationic Cyanines Are Potent Complex I Inhibitors and Specific in Vitro Dopaminergic Toxins with Mechanistic Similarities to Both Rotenone and MPP(.).

PubMed

Kadigamuwa, Chamila C; Mapa, Mapa S T; Wimalasena, Kandatege

2016-09-19

We have recently reported that simple lipophilic cationic cyanines are specific and potent dopaminergic toxins with a mechanism of toxicity similar to that of the Parkinsonian toxin MPP(+). In the present study, a group of fluorescent lipophilic cyanines have been used to further exploit the structure-activity relationship of the specific dopaminergic toxicity of cyanines. Here, we report that all cyanines tested were highly toxic to dopaminergic MN9D cells with IC50s in the range of 60-100 nM and not toxic to non-neuronal HepG2 cells parallel to that previously reported for 2,2'- and 4,4'-cyanines. All cyanines nonspecifically accumulate in the mitochondria of both MN9D and HepG2 cells at high concentrations, inhibit the mitochondrial complex I with the inhibition potencies similar to the potent complex I inhibitor, rotenone. They increase the reactive oxygen species (ROS) production specifically in dopaminergic cells causing apoptotic cell death. These and other findings suggest that the complex I inhibition, the expression of low levels of antioxidant enzymes, and presence of high levels of oxidatively labile radical propagator, dopamine, could be responsible for the specific increase in ROS production in dopaminergic cells. Thus, the predisposition of dopaminergic cells to produce high levels of ROS in response to mitochondrial toxins together with their inherent greater demand for energy may contribute to their specific vulnerability toward these toxins. The novel findings that cyanines are an unusual class of potent mitochondrial toxins with specific dopaminergic toxicity suggest that their presence in the environment could contribute to the etiology of PD similar to that of MPP(+) and rotenone.

Labile dissolved organic carbon supply limits hyporheic denitrification

Treesearch

Jay P. Zarnetske; Roy Haggerty; Steven M. Wondzell; Michelle A. Baker

2012-01-01

We used an in situ steady state 15N-labeled nitrate and acetate well-to-wells injection experiment to determine how the availability of labile dissolved organic carbon as acetate influences microbial denitrification in the hyporheic zone of an upland (third-order) agricultural stream.

Lability of Cd, Cu, and Zn in polluted soils treated with lime, beringite, and red mud and identification of a non-labile colloidal fraction of metals using istopic techniques.

PubMed

Lombi, Enzo; Hamon, Rebecca E; McGrath, Steve P; McLaughlin, Mike J

2003-03-01

The use of soil amendments has been proposed as a low input alternative for the remediation of metal polluted soils. However, little information is available concerning the stability, and therefore the longevity, of the remediation treatments when important soil parameters change. In this paper we investigate the effect of pH changes on the lability of heavy metals in soils treated with lime, beringite, and red mud using a modified isotopic dilution technique in combination with a stepwise acidification procedure. Significant amounts of nonlabile (fixed) Cu and Zn were found to be associated with colloids <0.2 microm in the solution phase. The results obtained indicated that the mobility of fixed colloidal metals is significant and increases with soil pH. This must be considered because most of the soil amendments are alkaline and increase soil pH. All the soil amendments significantly decreased the lability of Cd, Zn, and Cu in the soils as a whole. However, when the soils were re-acidified, the labile pool of metals increased sharply and in the case of lime and beringite, the lability of the metals was similar, at equal pH, to the untreated soil. In contrast the lability of metals in the red mud treated soils was always smaller than that in the untreated soils across the range of pH values tested. These results suggest that the mechanism of action of lime and beringite is similar and probably related to increased metal adsorption and precipitation of metal hydroxides and carbonates at high pH. In the case of red mud, a combination of pH dependent and independent mechanisms (possibly solid-phase diffusion or migration into micropores) may be responsible for the metal fixation observed.

Toxin yet not toxic: Botulinum toxin in dentistry.

PubMed

Archana, M S

2016-04-01

Paracelsus contrasted poisons from nonpoisons, stating that "All things are poisons, and there is nothing that is harmless; the dose alone decides that something is a poison". Living organisms, such as plants, animals, and microorganisms, constitute a huge source of pharmaceutically useful medicines and toxins. Depending on their source, toxins can be categorized as phytotoxins, mycotoxins, or zootoxins, which include venoms and bacterial toxins. Any toxin can be harmful or beneficial. Within the last 100 years, the perception of botulinum neurotoxin (BTX) has evolved from that of a poison to a versatile clinical agent with various uses. BTX plays a key role in the management of many orofacial and dental disorders. Its indications are rapidly expanding, with ongoing trials for further applications. However, despite its clinical use, what BTX specifically does in each condition is still not clear. The main aim of this review is to describe some of the unclear aspects of this potentially useful agent, with a focus on the current research in dentistry.

PTSD, alcohol dependence, and conduct problems: Distinct pathways via lability and disinhibition.

PubMed

Simons, Jeffrey S; Simons, Raluca M; O'Brien, Carol; Stoltenberg, Scott F; Keith, Jessica A; Hudson, Jaime A

2017-01-01

This study tested the role of affect lability and disinhibition in mediating associations between PTSD symptoms and two forms of alcohol-related problems, dependence syndrome symptoms (e.g., impaired control over consumption) and conduct problems (e.g., assault, risk behaviors). Genotype at the serotonin transporter linked polymorphic region (5-HTTLPR) was hypothesized to moderate associations between traumatic stress and PTSD symptoms. In addition, the study tested whether childhood traumatic stress moderated associations between combat trauma and PTSD symptoms. Participants were 270 OIF/OEF/OND veterans. The hypothesized model was largely supported. Participants with the low expression alleles of 5-HTTLPR (S or L G ) exhibited stronger associations between childhood (but not combat) traumatic stress and PTSD symptoms. Affect lability mediated the associations between PTSD symptoms and alcohol dependence symptoms. Behavioral disinhibition mediated associations between PTSD symptoms and conduct related problems. Conditional indirect effects indicated stronger associations between childhood traumatic stress and lability, behavioral disinhibition, alcohol consumption, AUD symptoms, and associated conduct problems via PTSD symptoms among those with the low expression 5-HTTLPR alleles. However, interactions between combat trauma and either childhood trauma or genotype were not significant. The results support the hypothesis that affect lability and behavioral disinhibition are potential intermediate traits with distinct associations with AUD and associated externalizing problems. Copyright © 2016 Elsevier Ltd. All rights reserved.

Clostridium spiroforme toxin is a binary toxin which ADP-ribosylates cellular actin.

PubMed

Popoff, M R; Boquet, P

1988-05-16

We have purified from Clostridium spiroforme strain 246 an heterogeneous population of proteins (Sa) ranging from 43 to 47 kilodaltons exhibiting ADP-ribosyl transferase activity as do C. botulinum C2 toxin component I or the ia chain of C. perfringens E iota toxin. C. spiriforme Sa had alone no activity upon injection in mice or inoculated to Vero cells. When spiroforme ADP ribosyl transferase were mixed with a trypsin activated protein (Sb) separated from C. spiroforme bacterial supernatant, a lethal effect in mice and cytotoxicity on Vero cells were recorded. The Sa cross-reacted immunologically with either the light chain of C. perfringens E iota toxin or the ADP-ribosyl transferase from C. difficile 196 strain. No immunological relatedness was observed between Sa and C2 toxin component I. C. spiroforme toxin is thus another binary toxin close to iota.

Millipede toxin

MedlinePlus

... The toxin that millipedes release keeps away most predators. Some large millipede species can spray these toxins ... Your local poison control center can be reached directly by calling the national toll-free Poison Help hotline (1-800-222-1222) from ...

Broadening and shifting of Bragg reflections of nanoscale-microtwinned LT-Ni3Sn2

NASA Astrophysics Data System (ADS)

Leineweber, Andreas; Krumeich, Frank

2013-12-01

The effect of nanoscale microtwinning of long-range ordered domains in LT-Ni3Sn2 on its diffraction behaviour was studied by X-ray powder diffraction and electron microscopy. LT-Ni3Sn2 exhibits a Ni2In/NiAs-type structure with a superstructure breaking the symmetry relative to the hexagonal high-temperature (HT) to the orthorhombic low-temperature (LT) phase, implying three different twin-domain orientations. The microstructure was generated by annealing HT-Ni3Sn2 considerably below the order-disorder transition temperature, establishing the LT phase avoiding too much domain coarsening. High-resolution electron microscopy reveals domain sizes of 100-200 Å compatible with the Scherrer broadening of the superstructure reflections recorded by X-ray diffraction. Whereas the orthorhombic symmetry of the LT phase leads in powder-diffraction patterns from coarse-domain size material to splitting of the fundamental reflections, this splitting does not occur for the LT-Ni3Sn2 with nanoscale domains. Instead, a (pseudo)hexagonal indexing is possible giving hexagonal lattice parameters, which are, however, incompatible with the positions of the superstructure reflections. This can be attributed to interference between X-rays scattered by the differently oriented, truly orthorhombic domains leading to merging of the fundamental reflections. These show pronounced anisotropic microstrain-like broadening, where the integral breadths ? on the reciprocal d-spacing scale of a series of higher order reflection increase in a non-linear fashion with upward curvature with the reciprocal d-spacings ? of these reflections. Such a type of unusual microstrain broadening appears to be typical for microstructures which are inhomogeneous on the nanoscale, and in which the structural inhomogeneities lead to small phase shifts of the scattered radiation from different locations (e.g. domains).

Assessment of Affect Lability: Psychometric Properties of the ALS-18.

PubMed

Contardi, Anna; Imperatori, Claudio; Amati, Italia; Balsamo, Michela; Innamorati, Marco

2018-01-01

Affect lability, an important aspect of emotion dysregulation, characterizes several psychiatric conditions. The short Affective Lability Scales (ALS-18) measures three aspects of changeability between euthymia and affect states (Anxiety/Depression, AD; Depression/Elation, DE; and Anger, Ang). The aim of our study was to investigate the psychometric characteristics of an Italian version of the ALS-18 in a sample of adults recruited from the general population. The sample was composed of 494 adults (343 women and 151 men) aged 18 and higher (mean age = 31.73 years, SD = 12.6). All participants were administered a checklist assessing socio-demographic variables, the ALS-18 and measures of depression and difficulties in emotion regulation. Confirmatory factor analyses indicated adequate fit of the three-factor model (RMSEA = 0.061, 95% CI = 0.054/0.069; CFI = 0.99; SRMR = 0.055), and the presence of a higher-order general factor. Internal consistency was satisfactory for all the lower-order dimensions and the general factor (ordinal α > 0.70). The ALS-18 was significantly associated with concurrent measures of depression and difficulties in emotion regulation. These findings indicate that the ALS-18 is a valid and reliable instrument for measuring affect lability, although discriminant validity of subdimensions scores could be problematic.

Ligand lability and chirality inversion in yb heterobimetallic catalysts.

PubMed

Di Bari, Lorenzo; Lelli, Moreno; Salvadori, Piero

2004-09-20

We have investigated the exchange dynamics between the free and bound ligand in K3[Yb[(R)-binol]3], the most active heterobimetallic lanthanoid catalyst for cyclic imine hydrophosphonylation; we found that the Yb-binol bond is labile. The rate constant for this exchange was determined through NMR saturation transfer experiments. Upon addition of (S)-binaphthol, ligand exchange leads to the formation of a small quantity of heterochiral complexes and, in the presence of a molar excess of (S)-binaphthol, to chirality inversion of the whole complex. This demonstrates that, in contrast to other analogous systems, K3[Yb(binol)3] displays a strong chiral discrimination, with the overwhelming preference for ligands of the same configuration. The lability of Yb-binol bond in THF may suggest a ligand-to-substrate exchange as a key step in the catalytic process.

Botulinum toxin in parkinsonism: The when, how, and which for botulinum toxin injections.

PubMed

Cardoso, Francisco

2018-06-01

The aim of this article is to provide a review of the use of injections of botulinum toxin in the management of selected symptoms and signs of Parkinson's disease and other forms of parkinsonism. Sialorrhea is defined as inability to control oral secretions, resulting in excessive saliva in the oropharynx. There is a high level of evidence for the treatment of sialorrhea in parkinsonism with injections of different forms of botulinum toxin type A as well as botulinum toxin type B. Tremor can be improved by the use of botulinum toxin injections but improved tremor control often leads to concomitant motor weakness, limiting its use. Levodopa induced dyskinesias are difficult to treat with botulinum toxin injections because of their variable frequency and direction. Apraxia of eyelid opening, a sign more commonly seen in progressive supranuclear palsy and other tauopathies, often improves after botulinum toxin injections. Recent data suggest that regardless of the underlying mechanism, pain in parkinsonism can be alleviated by botulinum toxin injections. Finally, freezing of gait, camptocormia and Pisa syndrome in parkinsonism almost invariably fail to respond to botulinum toxin injections. Copyright © 2017 Elsevier Ltd. All rights reserved.

Toxin Kid uncouples DNA replication and cell division to enforce retention of plasmid R1 in Escherichia coli cells.

PubMed

Pimentel, Belén; Nair, Radhika; Bermejo-Rodríguez, Camino; Preston, Mark A; Agu, Chukwuma A; Wang, Xindan; Bernal, Juan A; Sherratt, David J; de la Cueva-Méndez, Guillermo

2014-02-18

Worldwide dissemination of antibiotic resistance in bacteria is facilitated by plasmids that encode postsegregational killing (PSK) systems. These produce a stable toxin (T) and a labile antitoxin (A) conditioning cell survival to plasmid maintenance, because only this ensures neutralization of toxicity. Shortage of antibiotic alternatives and the link of TA pairs to PSK have stimulated the opinion that premature toxin activation could be used to kill these recalcitrant organisms in the clinic. However, validation of TA pairs as therapeutic targets requires unambiguous understanding of their mode of action, consequences for cell viability, and function in plasmids. Conflicting with widespread notions concerning these issues, we had proposed that the TA pair kis-kid (killing suppressor-killing determinant) might function as a plasmid rescue system and not as a PSK system, but this remained to be validated. Here, we aimed to clarify unsettled mechanistic aspects of Kid activation, and of the effects of this for kis-kid-bearing plasmids and their host cells. We confirm that activation of Kid occurs in cells that are about to lose the toxin-encoding plasmid, and we show that this provokes highly selective restriction of protein outputs that inhibits cell division temporarily, avoiding plasmid loss, and stimulates DNA replication, promoting plasmid rescue. Kis and Kid are conserved in plasmids encoding multiple antibiotic resistance genes, including extended spectrum β-lactamases, for which therapeutic options are scarce, and our findings advise against the activation of this TA pair to fight pathogens carrying these extrachromosomal DNAs.

Survey of A{sub LT'} asymmetries in semi-exclusive electron scattering on He4 and C12

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dan Protopopescu; et. Al.

2005-02-21

Single spin azimuthal asymmetries A{sub LT'} were measured at Jefferson Lab using 2.2 and 4.4 GeV longitudinally polarized electrons incident on {sup 4}He and {sup 12}C targets in the CLAS detector. A{sub LT'} is related to the imaginary part of the longitudinal-transverse interference and in quasifree nucleon knockout it provides an unambiguous signature for final state interactions (FSI). Experimental values of A{sub LT'} were found to be below 5%, typically |A{sub LT'}| < 3% for data with good statistical precision. Optical Model in Eikonal Approximation (OMEA) and Relativistic Multiple-Scattering Glauber Approximation (RMSGA) calculations are shown to be consistent with themore » measured asymmetries.« less

Differential Mobility Spectrometry for Improved Selectivity in Hydrophilic Interaction Liquid Chromatography-Tandem Mass Spectrometry Analysis of Paralytic Shellfish Toxins

NASA Astrophysics Data System (ADS)

Beach, Daniel G.

2017-08-01

Paralytic shellfish toxins (PSTs) are neurotoxins produced by dinoflagellates and cyanobacteria that cause paralytic shellfish poisoning in humans. PST quantitation by LC-MS is challenging because of their high polarity, lability as gas-phase ions, and large number of potentially interfering analogues. Differential mobility spectrometry (DMS) has the potential to improve the performance of LC-MS methods for PSTs in terms of selectivity and limits of detection. This work describes a comprehensive investigation of the separation of 16 regulated PSTs by DMS and the development of highly selective LC-DMS-MS methods for PST quantitation. The effects of all DMS parameters on the separation of PSTs from one another were first investigated in detail. The labile nature of 11α-gonyautoxin epimers gave unique insight into fragmentation of labile analytes before, during, and after the DMS analyzer. Two sets of DMS parameters were identified that either optimized the resolution of PSTs from one another or transmitted them at a limited number of compensation voltage (CV) values corresponding to structural subclasses. These were used to develop multidimensional LC-DMS-MS/MS methods using existing HILIC-MS/MS parameters. In both cases, improved selectivity was observed when using DMS, and the quantitative capabilities of a rapid UPLC-DMS-MS/MS method were evaluated. Limits of detection of the developed method were similar to those without DMS, and differences were highly analyte-dependant. Analysis of shellfish matrix reference materials showed good agreement with established methods. The developed methods will be useful in cases where specific matrix interferences are encountered in the LC-MS/MS analysis of PSTs in complex biological samples.

Pertussis toxin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sekura, R.D.; Moss, J.; Vaughan, M.

1985-01-01

This book contains 13 selections. Some of the titles are: Genetic and Functional Studies of Pertussis Toxin Substrates; Effect of Pertussis Toxin on the Hormonal Responsiveness of Different Tissues; Extracellular Adenylate Cyclase of Bordetella pertussis; and GTP-Regulatory Proteins are Introcellular Messagers: A Model for Hormone Action.

PmLT, a C-type lectin specific to hepatopancreas is involved in the innate defense of the shrimp Penaeus monodon.

PubMed

Ma, Tracy Hoi-Tung; Benzie, John A H; He, Jian-Guo; Chan, Siu-Ming

2008-11-01

A diverse class of proteins called lectins plays a major role in shrimp innate immunity. In this study, the cDNA encoding a C-type lectin of Penaeus monodon (PmLT) was cloned, and its potential role examined. Despite the low overall amino acid sequence identity with other animal lectins, PmLT includes conserved carbohydrate recognition domains (CRDs) characteristic of animal C-type lectins. Unlike the other two P. monodon lectin-like proteins described to date that have one CRD, PmLT has two CRDs. The first CRD contains a QPD motif with specificity for binding galactose, while the second CRD contains a EPN motif for binding mannose. PmLT transcripts can be detected in the hepatopancreas but not in other tissues. Expression studies showed that PmLT mRNA transcript level decreased initially and then gradually increased after whole shrimp or hepatopancreas tissue fragments were treated with white spot syndrome virus (WSSV) extract but were not affected by bacteria. Using anti-rPmLT antibody, PmLT was detected only in the hepatopancreas specific F cells (Hpf). In vitro encapsulation assay showed that agarose beads coated with rPmLT were encapsulated by hemocytes indicating a role in innate immune response. In summary, PmLT is produced in the hepatopancreas and may act as a pattern recognition protein for viral pathogens and also activates the innate immune responses of the shrimp to bacteria. The dual-CRD structure of PmLT may assist the recognition of diverse pathogens.

The evolution of labile traits in sex- and age-structured populations.

PubMed

Childs, Dylan Z; Sheldon, Ben C; Rees, Mark

2016-03-01

Many quantitative traits are labile (e.g. somatic growth rate, reproductive timing and investment), varying over the life cycle as a result of behavioural adaptation, developmental processes and plastic responses to the environment. At the population level, selection can alter the distribution of such traits across age classes and among generations. Despite a growing body of theoretical research exploring the evolutionary dynamics of labile traits, a data-driven framework for incorporating such traits into demographic models has not yet been developed. Integral projection models (IPMs) are increasingly being used to understand the interplay between changes in labile characters, life histories and population dynamics. One limitation of the IPM approach is that it relies on phenotypic associations between parents and offspring traits to capture inheritance. However, it is well-established that many different processes may drive these associations, and currently, no clear consensus has emerged on how to model micro-evolutionary dynamics in an IPM framework. We show how to embed quantitative genetic models of inheritance of labile traits into age-structured, two-sex models that resemble standard IPMs. Commonly used statistical tools such as GLMs and their mixed model counterparts can then be used for model parameterization. We illustrate the methodology through development of a simple model of egg-laying date evolution, parameterized using data from a population of Great tits (Parus major). We demonstrate how our framework can be used to project the joint dynamics of species' traits and population density. We then develop a simple extension of the age-structured Price equation (ASPE) for two-sex populations, and apply this to examine the age-specific contributions of different processes to change in the mean phenotype and breeding value. The data-driven framework we outline here has the potential to facilitate greater insight into the nature of selection and its

Production of a fusion protein consisting of the enterotoxigenic Escherichia coli heat-labile toxin B subunit and a tuberculosis antigen in Arabidopsis thaliana.

PubMed

Rigano, M M; Alvarez, M L; Pinkhasov, J; Jin, Y; Sala, F; Arntzen, C J; Walmsley, A M

2004-02-01

Transgenic plants are potentially safe and inexpensive vehicles to produce and mucosally deliver protective antigens. However, the application of this technology is limited by the poor response of the immune system to non-particulate, subunit vaccines. Co-delivery of therapeutic proteins with carrier proteins could increase the effectiveness of the antigen. This paper reports the ability of transgenic Arabidopsis thaliana plants to produce a fusion protein consisting of the B subunit of the Escherichia coli heat-labile enterotoxin and a 6 kDa tuberculosis antigen, the early secretory antigenic target ESAT-6. Both components of the fusion protein were detected using GM1-ganglioside-dependent enzyme-linked immunosorbant assay. This suggested the fusion protein retained both its native antigenicity and the ability to form pentamers.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Won, JaeSeon; Nam, PilWon; Lee, YongChan

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 Fabmore » 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.« less

Antibody-based bacterial toxin detection

NASA Astrophysics Data System (ADS)

Menking, Darrell E.; Heitz, Jonathon M.; Anis, Nabil A.; Thompson, Roy G.

1994-03-01

Fiber optic evanescent fluorosensors are under investigation in our laboratory for the study of drug-receptor interactions for detection of threat agents and antibody-antigen interactions for detection of biological toxins. In a one step assay, antibodies against Cholera toxin or Staphylococcus Enterotoxin B were noncovalently immobilized on quartz fibers and probed with fluorescein-isothiocyanate (FITC)-labeled toxins. In the two-step assay, Cholera toxin or Botulinum toxoid A was immobilized onto the fiber, followed by incubation in an antiserum or partially purified antitoxin IgG. These were then probed with FITC-anti-IgG antibodies. Unlabeled toxins competed with labeled toxins or antitoxin IgG in a dose-dependent manner and the detection of the toxins was in the nanomolar range.

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

Lachesana tarabaevi, an expert in membrane-active toxins.

PubMed

Kuzmenkov, Alexey I; Sachkova, Maria Y; Kovalchuk, Sergey I; Grishin, Eugene V; Vassilevski, Alexander A

2016-08-15

In the present study, we show that venom of the ant spider Lachesana tarabaevi is unique in terms of molecular composition and toxicity. Whereas venom of most spiders studied is rich in disulfide-containing neurotoxic peptides, L. tarabaevi relies on the production of linear (no disulfide bridges) cytolytic polypeptides. We performed full-scale peptidomic examination of L. tarabaevi venom supported by cDNA library analysis. As a result, we identified several dozen components, and a majority (∼80% of total venom protein) exhibited membrane-active properties. In total, 33 membrane-interacting polypeptides (length of 18-79 amino acid residues) comprise five major groups: repetitive polypeptide elements (Rpe), latarcins (Ltc), met-lysines (MLys), cyto-insectotoxins (CIT) and latartoxins (LtTx). Rpe are short (18 residues) amphiphilic molecules that are encoded by the same genes as antimicrobial peptides Ltc 4a and 4b. Isolation of Rpe confirms the validity of the iPQM (inverted processing quadruplet motif) proposed to mark the cleavage sites in spider toxin precursors that are processed into several mature chains. MLys (51 residues) present 'idealized' amphiphilicity when modelled in a helical wheel projection with sharply demarcated sectors of hydrophobic, cationic and anionic residues. Four families of CIT (61-79 residues) are the primary weapon of the spider, accounting for its venom toxicity. Toxins from the CIT 1 and 2 families have a modular structure consisting of two shorter Ltc-like peptides. We demonstrate that in CIT 1a, these two parts act in synergy when they are covalently linked. This finding supports the assumption that CIT have evolved through the joining of two shorter membrane-active peptides into one larger molecule. © 2016 The Author(s). published by Portland Press Limited on behalf of the Biochemical Society.

Upregulation of transferrin receptor-1 induces cholangiocarcinoma progression via induction of labile iron pool.

PubMed

Jamnongkan, Wassana; Thanan, Raynoo; Techasen, Anchalee; Namwat, Nisana; Loilome, Watcharin; Intarawichian, Piyapharom; Titapun, Attapol; Yongvanit, Puangrat

2017-07-01

Labile iron pool is a cellular source of ions available for Fenton reactions resulting in oxidative stress. Living organisms avoid an excess of free irons by a tight control of iron homeostasis. We investigated the altered expression of iron regulatory proteins and iron discrimination in the development of liver fluke-associated cholangiocarcinoma. Additionally, the levels of labile iron pool and the functions of transferrin receptor-1 on cholangiocarcinoma development were also identified. Iron deposition was determined using the Prussian blue staining method in human cholangiocarcinoma tissues. We investigated the alteration of iron regulatory proteins including transferrin, transferrin receptor-1, ferritin, ferroportin, hepcidin, and divalent metal transporter-1 in cholangiocarcinoma tissues using immunohistochemistry. The clinicopathological data of cholangiocarcinoma patients and the expressions of proteins were analyzed. Moreover, the level of intracellular labile iron pool in cholangiocarcinoma cell lines was identified by the RhoNox-1 staining method. We further demonstrated transferrin receptor-1 functions on cell proliferation and migration upon small interfering RNA for human transferrin receptor 1 transfection. Results show that Iron was strongly stained in tumor tissues, whereas negative staining was observed in normal bile ducts of healthy donors. Interestingly, high iron accumulation was significantly correlated with poor prognosis of cholangiocarcinoma patients. The expressions of iron regulatory proteins in human cholangiocarcinoma tissues and normal liver from cadaveric donors revealed that transferrin receptor-1 expression was increased in the cancer cells of cholangiocarcinoma tissues when compared with the adjacent normal bile ducts and was significantly correlated with cholangiocarcinoma metastasis. Labile iron pool level and transferrin receptor-1 expression were significantly increased in KKU-214 and KKU-213 when compared with cholangiocyte

Prevalence of adhesin and toxin genes in E. coli strains isolated from diarrheic and non-diarrheic pigs from smallholder herds in northern and eastern Uganda.

PubMed

Ikwap, Kokas; Larsson, Jenny; Jacobson, Magdalena; Owiny, David Okello; Nasinyama, George William; Nabukenya, Immaculate; Mattsson, Sigbrit; Aspan, Anna; Erume, Joseph

2016-08-05

Enterotoxigenic E. coli (ETEC) significantly contribute to diarrhea in piglets and weaners. The smallholder pig producers in Uganda identified diarrhea as one of the major problems especially in piglets. The aim of this study was to; i) characterize the virulence factors of E. coli strains isolated from diarrheic and non-diarrheic suckling piglets and weaners from smallholder herds in northern and eastern Uganda and ii) identify and describe the post-mortem picture of ETEC infection in severely diarrheic piglets. Rectal swab samples were collected from 83 piglets and weaners in 20 herds and isolated E. coli were characterized by PCR, serotyping and hemolysis. The E. coli strains carried genes for the heat stable toxins STa, STb and EAST1 and adhesins F4 and AIDA-I. The genes for the heat labile toxin LT and adhesins F5, F6, F18 and F41 were not detected in any of the E. coli isolates. Where the serogroup could be identified, E. coli isolates from the same diarrheic pig belonged to the same serogroup. The prevalence of EAST1, STb, Stx2e, STa, AIDA-I, and F4 in the E. coli isolates from suckling piglets and weaners (diarrheic and non-diarrheic combined) was 29, 26.5, 2.4, 1.2, 16, and 8.4 %, respectively. However the prevalence of F4 and AIDA-I in E. coli from diarrheic suckling piglets alone was 22.2 and 20 %, respectively. There was no significant difference in the prevalence of the individual virulence factors in E. coli from the diarrheic and non-diarrheic pigs (p > 0.05). The main ETEC strains isolated from diarrheic and non-diarrheic pigs included F4/STb/EAST1 (7.2 %), F4/STb (1.2 %), AIDA/STb/EAST1 (8 %) and AIDA/STb (8 %). At post-mortem, two diarrheic suckling piglets carrying ETEC showed intact intestinal villi, enterocytes and brush border but with a layer of cells attached to the brush border, suggestive of ETEC infections. This study has shown that the F4 fimbriae is the most predominant in E. coli from diarrheic piglets in the study area and

Electrodermal lability as an indicator for subjective sleepiness during total sleep deprivation.

PubMed

Michael, Lars; Passmann, Sven; Becker, Ruth

2012-08-01

The present study addresses the suitability of electrodermal lability as an indicator of individual vulnerability to the effects of total sleep deprivation. During two complete circadian cycles, the effects of 48h of total sleep deprivation on physiological measures (electrodermal activity and body temperature), subjective sleepiness (measured by visual analogue scale and tiredness symptom scale) and task performance (reaction time and errors in a go/no go task) were investigated. Analyses of variance with repeated measures revealed substantial decreases of the number of skin conductance responses, body temperature, and increases for subjective sleepiness, reaction time and error rates. For all changes, strong circadian oscillations could be observed as well. The electrodermal more labile subgroup reported higher subjective sleepiness compared with electrodermal more stable participants, but showed no differences in the time courses of body temperature and task performance. Therefore, electrodermal lability seems to be a specific indicator for the changes in subjective sleepiness due to total sleep deprivation and circadian oscillations, but not a suitable indicator for vulnerability to the effects of sleep deprivation per se. © 2011 European Sleep Research Society.

Newer insights into the mechanism of action of Psidium guajava L. leaves in infectious diarrhoea

PubMed Central

2010-01-01

Background Psidium guajava L., Myrtaceae, is used widely in traditional medicine for the treatment of diarrhoea, dysentery, gastroenteritis, stomachaches, and indigestion. However, the effect of the leaf extract of P. guajava on the pathogenesis of infectious diarrhoea has not been studied. The present study evaluates the effect of a hot aqueous extract (decoction) of dried leaves of P. guajava on parameters associated with pathogenicity of infectious diarrhoea. The aim was to understand its possible mechanism(s) of action in controlling infectious diarrhoea and compare it with quercetin, one of the most reported active constituents of P. guajava with antidiarrhoeal activity. Methods The crude decoction and quercetin were studied for their antibacterial activity and effect on virulence features of common diarrhoeal pathogens viz. colonization of epithelial cells and production and action of enterotoxins. Colonization as measured by adherence of enteropathogenic Escherichia coli (EPEC) and invasion of enteroinvasive E. coli (EIEC) and Shigella flexneri was assessed using HEp-2 cell line. The production of E. coli heat labile toxin (LT) and cholera toxin (CT) and their binding to ganglioside monosialic acid (GM1) were studied by GM1-ELISA whereas the production and action of E. coli heat stable toxin (ST) was assessed by suckling mouse assay. Results The decoction of P. guajava showed antibacterial activity towards S. flexneri and Vibrio cholerae. It decreased production of both LT and CT and their binding to GM1. However, it had no effect on production and action of ST. The decoction also inhibited the adherence of EPEC and invasion by both EIEC and S. flexneri to HEp-2 cells. Quercetin, on the other hand, had no antibacterial activity at the concentrations used nor did it affect any of the enterotoxins. Although it did not affect adherence of EPEC, it inhibited the invasion of both EIEC and S. flexneri to HEp-2 cells. Conclusion Collectively, the results indicate

Newer insights into the mechanism of action of Psidium guajava L. leaves in infectious diarrhoea.

PubMed

Birdi, Tannaz; Daswani, Poonam; Brijesh, S; Tetali, Pundarikakshudu; Natu, Arvind; Antia, Noshir

2010-06-28

Psidium guajava L., Myrtaceae, is used widely in traditional medicine for the treatment of diarrhoea, dysentery, gastroenteritis, stomachaches, and indigestion. However, the effect of the leaf extract of P. guajava on the pathogenesis of infectious diarrhoea has not been studied. The present study evaluates the effect of a hot aqueous extract (decoction) of dried leaves of P. guajava on parameters associated with pathogenicity of infectious diarrhoea. The aim was to understand its possible mechanism(s) of action in controlling infectious diarrhoea and compare it with quercetin, one of the most reported active constituents of P. guajava with antidiarrhoeal activity. The crude decoction and quercetin were studied for their antibacterial activity and effect on virulence features of common diarrhoeal pathogens viz. colonization of epithelial cells and production and action of enterotoxins. Colonization as measured by adherence of enteropathogenic Escherichia coli (EPEC) and invasion of enteroinvasive E. coli (EIEC) and Shigella flexneri was assessed using HEp-2 cell line. The production of E. coli heat labile toxin (LT) and cholera toxin (CT) and their binding to ganglioside monosialic acid (GM1) were studied by GM1-ELISA whereas the production and action of E. coli heat stable toxin (ST) was assessed by suckling mouse assay. The decoction of P. guajava showed antibacterial activity towards S. flexneri and Vibrio cholerae. It decreased production of both LT and CT and their binding to GM1. However, it had no effect on production and action of ST. The decoction also inhibited the adherence of EPEC and invasion by both EIEC and S. flexneri to HEp-2 cells. Quercetin, on the other hand, had no antibacterial activity at the concentrations used nor did it affect any of the enterotoxins. Although it did not affect adherence of EPEC, it inhibited the invasion of both EIEC and S. flexneri to HEp-2 cells. Collectively, the results indicate that the decoction of P. guajava leaves

Toxin-Based Therapeutic Approaches

PubMed Central

Shapira, Assaf; Benhar, Itai

2010-01-01

Protein toxins confer a defense against predation/grazing or a superior pathogenic competence upon the producing organism. Such toxins have been perfected through evolution in poisonous animals/plants and pathogenic bacteria. Over the past five decades, a lot of effort has been invested in studying their mechanism of action, the way they contribute to pathogenicity and in the development of antidotes that neutralize their action. In parallel, many research groups turned to explore the pharmaceutical potential of such toxins when they are used to efficiently impair essential cellular processes and/or damage the integrity of their target cells. The following review summarizes major advances in the field of toxin based therapeutics and offers a comprehensive description of the mode of action of each applied toxin. PMID:22069564

A Biologically-Based Computational Approach to Drug Repurposing for Anthrax Infection.

PubMed

Bai, Jane P F; Sakellaropoulos, Theodore; Alexopoulos, Leonidas G

2017-03-10

Developing drugs to treat the toxic effects of lethal toxin (LT) and edema toxin (ET) produced by B. anthracis is of global interest . We utilized a computational approach to score 474 drugs/compounds for their ability to reverse the toxic effects of anthrax toxins. For each toxin or drug/compound, we constructed an activity network by using its differentially expressed genes, molecular targets, and protein interactions. Gene expression profiles of drugs were obtained from the Connectivity Map and those of anthrax toxins in human alveolar macrophages were obtained from the Gene Expression Omnibus. Drug rankings were based on the ability of a drug/compound's mode of action in the form of a signaling network to reverse the effects of anthrax toxins; literature reports were used to verify the top 10 and bottom 10 drugs/compounds identified. Simvastatin and bepridil with reported in vitro potency for protecting cells from LT and ET toxicities were computationally ranked fourth and eighth. The other top 10 drugs were fenofibrate, dihydroergotamine, cotinine, amantadine, mephenytoin, sotalol, ifosfamide, and mefloquine; literature mining revealed their potential protective effects from LT and ET toxicities. These drugs are worthy of investigation for their therapeutic benefits and might be used in combination with antibiotics for treating B. anthracis infection.

A Biologically-Based Computational Approach to Drug Repurposing for Anthrax Infection

PubMed Central

Bai, Jane P. F.; Sakellaropoulos, Theodore; Alexopoulos, Leonidas G.

2017-01-01

Developing drugs to treat the toxic effects of lethal toxin (LT) and edema toxin (ET) produced by B. anthracis is of global interest. We utilized a computational approach to score 474 drugs/compounds for their ability to reverse the toxic effects of anthrax toxins. For each toxin or drug/compound, we constructed an activity network by using its differentially expressed genes, molecular targets, and protein interactions. Gene expression profiles of drugs were obtained from the Connectivity Map and those of anthrax toxins in human alveolar macrophages were obtained from the Gene Expression Omnibus. Drug rankings were based on the ability of a drug/compound’s mode of action in the form of a signaling network to reverse the effects of anthrax toxins; literature reports were used to verify the top 10 and bottom 10 drugs/compounds identified. Simvastatin and bepridil with reported in vitro potency for protecting cells from LT and ET toxicities were computationally ranked fourth and eighth. The other top 10 drugs were fenofibrate, dihydroergotamine, cotinine, amantadine, mephenytoin, sotalol, ifosfamide, and mefloquine; literature mining revealed their potential protective effects from LT and ET toxicities. These drugs are worthy of investigation for their therapeutic benefits and might be used in combination with antibiotics for treating B. anthracis infection. PMID:28287432

CysLT1 receptor-induced human airway smooth muscle cells proliferation requires ROS generation, EGF receptor transactivation and ERK1/2 phosphorylation

PubMed Central

Ravasi, Saula; Citro, Simona; Viviani, Barbara; Capra, Valérie; Rovati, G Enrico

2006-01-01

Background Cysteine-containing leukotrienes (cysteinyl-LTs) are pivotal inflammatory mediators that play important roles in the pathophysiology of asthma, allergic rhinitis, and other inflammatory conditions. In particular, cysteinyl-LTs exert a variety of effects with relevance to the aetiology of asthma such as smooth muscle contraction, eosinophil recruitment, increased microvascular permeability, enhanced mucus secretion and decreased mucus transport and, finally, airway smooth muscle cells (ASMC) proliferation. We used human ASMC (HASMC) to identify the signal transduction pathway(s) of the leukotriene D4 (LTD4)-induced DNA synthesis. Methods Proliferation of primary HASMC was measured by [3H]thymidine incorporation. Phosphorylation of EGF receptor (EGF-R) and ERK1/2 was assessed with a polyclonal anti-EGF-R or anti-phosphoERKl/2 monoclonal antibody. A Ras pull-down assay kit was used to evaluate Ras activation. The production of reactive oxygen species (ROS) was estimated by measuring dichlorodihydrofluorescein (DCF) oxidation. Results We demonstrate that in HASMC LTD4-stimulated thymidine incorporation and potentiation of EGF-induced mitogenic signaling mostly depends upon EGF-R transactivation through the stimulation of CysLT1-R. Accordingly, we found that LTD4 stimulation was able to trigger the increase of Ras-GTP and, in turn, to activate ERK1/2. We show here that EGF-R transactivation was sensitive to pertussis toxin (PTX) and phosphoinositide 3-kinase (PI3K) inhibitors and that it occurred independently from Src activity, despite the observation of a strong impairment of LTD4-induced DNA synthesis following Src inhibition. More interestingly, CysLT1-R stimulation increased the production of ROS and N-acetylcysteine (NAC) abolished LTD4-induced EGF-R phosphorylation and thymidine incorporation. Conclusion Collectively, our data demonstrate that in HASMC LTD4 stimulation of a Gi/o coupled CysLT1-R triggers the transactivation of the EGF-R through the

The discovery of cholera - like enterotoxins produced by Escherichia coli causing secretory diarrhoea in humans

PubMed Central

Sack, R. Bradley

2011-01-01

Non-vibrio cholera has been recognized as a clinical entity for as long as cholera was known to be caused by Vibrio cholerae. Until 1968, the aetiologic agent of this syndrome was not known. Following a series of studies in patients with non-vibrio cholera it was found that these patients had large concentrations of Escherichia coli in the small bowel and stools which produced cholera toxin-like enterotoxins, and had fluid and electrolyte transport abnormalities in the small bowel similar to patients with documented cholera. Furthermore, these patients developed antibodies to the cholera-like enterotoxin. Later studies showed that these strains, when fed to volunteers produced a cholera-like disease and that two enterotoxins were found to be produced by these organisms: a heat-labile enterotoxin (LT) which is nearly identical to cholera toxin, and a heat-stable enterotoxin (ST), a small molecular weight polypeptide. E. coli that produced one or both of these enterotoxins were designated enterotoxigenic E. coli (ETEC). ETEC are now known not only to cause a severe cholera-like illness, but to be the most common bacterial cause of acute diarrhoea in children in the developing world, and to be the most common cause of travellers’ diarrhoea in persons who visit the developing world. PMID:21415491

Toxins of Prokaryotic Toxin-Antitoxin Systems with Sequence-Specific Endoribonuclease Activity

PubMed Central

Masuda, Hisako; Inouye, Masayori

2017-01-01

Protein translation is the most common target of toxin-antitoxin system (TA) toxins. Sequence-specific endoribonucleases digest RNA in a sequence-specific manner, thereby blocking translation. While past studies mainly focused on the digestion of mRNA, recent analysis revealed that toxins can also digest tRNA, rRNA and tmRNA. Purified toxins can digest single-stranded portions of RNA containing recognition sequences in the absence of ribosome in vitro. However, increasing evidence suggests that in vivo digestion may occur in association with ribosomes. Despite the prevalence of recognition sequences in many mRNA, preferential digestion seems to occur at specific positions within mRNA and also in certain reading frames. In this review, a variety of tools utilized to study the nuclease activities of toxins over the past 15 years will be reviewed. A recent adaptation of an RNA-seq-based technique to analyze entire sets of cellular RNA will be introduced with an emphasis on its strength in identifying novel targets and redefining recognition sequences. The differences in biochemical properties and postulated physiological roles will also be discussed. PMID:28420090

An anthrax toxin variant with an improved activity in tumor targeting

PubMed Central

Wein, Alexander N.; Peters, Diane E.; Valivullah, Zaheer; Hoover, Benjamin J.; Tatineni, Aparna; Ma, Qian; Fattah, Rasem; Bugge, Thomas H.; Leppla, Stephen H.; Liu, Shihui

2015-01-01

Anthrax lethal toxin (LT) is an A-B type toxin secreted by Bacillus anthracis, consisting of the cellular binding moiety, protective antigen (PA), and the catalytic moiety, lethal factor (LF). To target cells, PA binds to cell-surface receptors and is then proteolytically processed forming a LF-binding competent PA oligomer where each LF binding site is comprised of three subsites on two adjacent PA monomers. We previously generated PA-U2-R200A, a urokinase-activated PA variant with LF-binding subsite II residue Arg200 mutated to Ala, and PA-L1-I210A, a matrix metalloproteinase-activated PA variant with subsite III residue Ile210 mutated to Ala. PA-U2-R200A and PA-L1-I210A displayed reduced cytotoxicity when used singly. However, when combined, they formed LF-binding competent heterogeneous oligomers by intermolecular complementation, and achieved high specificity in tumor targeting. Nevertheless, each of these proteins, in particular PA-L1-I210A, retained residual LF-binding ability. In this work, we screened a library containing all possible amino acid substitutions for LF-binding site to find variants with activity strictly dependent upon intermolecular complementation. PA-I207R was identified as an excellent replacement for the original clockwise-side variant, PA-I210A. Consequently, the new combination of PA-L1-I207R and PA-U2-R200A showed potent anti-tumor activity and low toxicity, exceeding the performance of the original combination, and warranting further investigation. PMID:26584669

Improved purification process for cholera toxin and its application to the quantification of residual toxin in cholera vaccines.

PubMed

Jang, Hyun; Kim, Hyo Seung; Kim, Jeong Ah; Seo, Jin Ho; Carbis, Rodney

2009-01-01

A simplified method for the purification of cholera toxin was developed. The 569B strain of Vibrio cholerae, a recognized hyper-producer of cholera toxin, was propagated in a bioreactor under conditions that promote the production of the toxin. The toxin was separated from the bacterial cells using 0.2-microm crossflow microfiltration, the clarified toxin was passed through the membrane into the permeate, and the bacterial cells were retained in the retentate. The 0.2-microm permeate was then concentrated 3-fold and diafiltered against 10 mM phosphate buffer, pH 7.6, using 30-kDa crossflow ultrafiltration. The concentrated toxin was loaded onto a cation exchange column, the toxin was bound to the column, and most of the impurities were passed unimpeded through the column. The toxin was eluted with a salt gradient of phosphate buffer, pH7.0, containing 1.0M NaCl. The peak containing the toxin was assayed for cholera toxin and protein and the purity was determined to be 92%. The toxin peak had a low endotoxin level of 3.1 EU/microg of toxin. The purified toxin was used to prepare antiserum against whole toxin, which was used in a G(M1) ganglioside-binding ELISA to determine residual levels of toxin in an oral inactivated whole-cell cholera vaccine. The G(M1) ganglioside-binding ELISA was shown to be very sensitive and capable of detecting as little as 1 ng/ml of cholera toxin.

Estimating soil labile organic carbon and potential turnover rates using a sequential fumigation–incubation procedure.

Treesearch

X.M. Zoua; H.H. Ruanc; Y. Fua; X.D. Yanga; L.Q. Sha

2005-01-01

Labile carbon is the fraction of soil organic carbon with most rapid turnover times and its oxidation drives the flux of CO2 between soils and atmosphere. Available chemical and physical fractionation methods for estimating soil labile organic carbon are indirect and lack a clear biological definition. We have modified the well-established Jenkinson and Powlson’s...

Prophylactic Administration of Bacterially Derived Immunomodulators Improves the Outcome of Influenza Virus Infection in a Murine Model▿

PubMed Central

Norton, Elizabeth B.; Clements, John D.; Voss, Thomas G.; Cárdenas-Freytag, Lucia

2010-01-01

Prophylactic or therapeutic immunomodulation is an antigen-independent strategy that induces nonspecific immune system activation, thereby enhancing host defense to disease. In this study, we investigated the effect of prophylactic immunomodulation on the outcome of influenza virus infection using three bacterially derived immune-enhancing agents known for promoting distinct immunological profiles. BALB/c mice were treated nasally with either cholera toxin (CT), a mutant form of the CT-related Escherichia coli heat-labile enterotoxin designated LT(R192G), or CpG oligodeoxynucleotide. Mice were subsequently challenged with a lethal dose of influenza A/PR/8/34 virus 24 h after the last immunomodulation treatment and either monitored for survival or sacrificed postchallenge for viral and immunological analysis. Treatment with the three immunomodulators prevented or delayed mortality and weight loss, but only CT and LT(R192G) significantly reduced initial lung viral loads as measured by plaque assay. Analysis performed 4 days postinfection indicated that prophylactic treatments with CT, LT(R192G), or CpG resulted in significantly increased numbers of CD4 T cells, B cells, and dendritic cells and altered costimulatory marker expression in the airways of infected mice, coinciding with reduced expression of pulmonary chemokines and the appearance of inducible bronchus-associated lymphoid tissue-like structures in the lungs. Collectively, these results suggest that, despite different immunomodulatory mechanisms, CT, LT(R192G), and CpG induce an initial inflammatory process and enhance the immune response to primary influenza virus challenge while preventing potentially damaging chemokine expression. These studies provide insight into the immunological parameters and immune modulation strategies that have the potential to enhance the nonspecific host response to influenza virus infection. PMID:20053748

Clostridium difficile binary toxin CDT

PubMed Central

Gerding, Dale N; Johnson, Stuart; Rupnik, Maja; Aktories, Klaus

2014-01-01

Binary toxin (CDT) is frequently observed in Clostridium difficile strains associated with increased severity of C. difficile infection (CDI). CDT belongs to the family of binary ADP-ribosylating toxins consisting of two separate toxin components: CDTa, the enzymatic ADP-ribosyltransferase which modifies actin, and CDTb which binds to host cells and translocates CDTa into the cytosol. CDTb is activated by serine proteases and binds to lipolysis stimulated lipoprotein receptor. ADP-ribosylation induces depolymerization of the actin cytoskeleton. Toxin-induced actin depolymerization also produces microtubule-based membrane protrusions which form a network on epithelial cells and increase bacterial adherence. Multiple clinical studies indicate an association between binary toxin genes in C. difficile and increased 30-d CDI mortality independent of PCR ribotype. Further studies including measures of binary toxin in stool, analyses of CDI mortality caused by CDT-producing strains, and examination of the relationship of CDT expression to TcdA and TcdB toxin variants and PCR ribotypes are needed. PMID:24253566

DEMONSTRATION BULLETIN: LOW TEMPERATURE THERMAL TREATMENT (LT3®) SYSTEM

EPA Science Inventory

The Roy F. Weston, Inc. (Weston) low temperature thermal treatment (LT³®) system thermally desorbs organic compounds from contaminated soil without heating the soil to combustion temperatures. The transportable system is comprised of equipment assembled on thre...

Designing an efficient LT-code with unequal error protection for image transmission

NASA Astrophysics Data System (ADS)

S. Marques, F.; Schwartz, C.; Pinho, M. S.; Finamore, W. A.

2015-10-01

The use of images from earth observation satellites is spread over different applications, such as a car navigation systems and a disaster monitoring. In general, those images are captured by on board imaging devices and must be transmitted to the Earth using a communication system. Even though a high resolution image can produce a better Quality of Service, it leads to transmitters with high bit rate which require a large bandwidth and expend a large amount of energy. Therefore, it is very important to design efficient communication systems. From communication theory, it is well known that a source encoder is crucial in an efficient system. In a remote sensing satellite image transmission, this efficiency is achieved by using an image compressor, to reduce the amount of data which must be transmitted. The Consultative Committee for Space Data Systems (CCSDS), a multinational forum for the development of communications and data system standards for space flight, establishes a recommended standard for a data compression algorithm for images from space systems. Unfortunately, in the satellite communication channel, the transmitted signal is corrupted by the presence of noise, interference signals, etc. Therefore, the receiver of a digital communication system may fail to recover the transmitted bit. Actually, a channel code can be used to reduce the effect of this failure. In 2002, the Luby Transform code (LT-code) was introduced and it was shown that it was very efficient when the binary erasure channel model was used. Since the effect of the bit recovery failure depends on the position of the bit in the compressed image stream, in the last decade many e orts have been made to develop LT-code with unequal error protection. In 2012, Arslan et al. showed improvements when LT-codes with unequal error protection were used in images compressed by SPIHT algorithm. The techniques presented by Arslan et al. can be adapted to work with the algorithm for image compression

Circulating concentrations of free thyroxine after an oral intake of liquid LT4 taken either during fasting conditions or at breakfast.

PubMed

Marina, Michela; Ceda, Gian Paolo; Aloe, Rosalia; Gnocchi, Cecilia; Ceresini, Graziano

2017-01-16

Liquid levothyroxine (LT4) given at breakfast normalizes TSH in hypothyroid patients. However, a few studies are available on circulating free thyroxine (FT4) concentrations after liquid vs solid LT4 preparations. During an "ad interim" analysis on serum FT4 after 200 mcg liquid LT4 consumption while fasting in thyroidectomized thyroid cancer patients, we found that seven subjects fortuitously took liquid LT4 at breakfast. As established in the original protocol, serum FT4 was measured both at baseline as well as at 3 and 4 hours after solid or liquid LT4 consumption. We compared serum profile of FT4 in these subjects with those obtained in other subjects participating in the same study who took liquid LT4 (n. 7 subjects) or solid LT4 (n. 7 subjects) while fasting. The percentage increase of circulating FT4 was calculated at the above reported peak-times over the baseline values. Circulating FT4 increased of about 40% in each group of subjects at both the 3rd and the 4th hour with no difference between these two time points in either group. The maximum FT4 % increase, irrespective of the time point, was 44.62 ± 3.05 (Mean ± SE), 44.84 ± 5.43, and 43.83 ± 1.30 after fasting solid, fasting liquid, and breakfast liquid LT4 consumption, respectively, with no differences among the three groups. Circulating FT4 obtained after 3 and 4 hours from the ingestion of 200 mcg liquid LT4 is not influenced by meal and is comparable with that observed after solid LT4 preparations ingested while fasting.

Toxin Kid uncouples DNA replication and cell division to enforce retention of plasmid R1 in Escherichia coli cells

PubMed Central

Pimentel, Belén; Nair, Radhika; Bermejo-Rodríguez, Camino; Preston, Mark A.; Agu, Chukwuma A.; Wang, Xindan; Bernal, Juan A.; Sherratt, David J.; de la Cueva-Méndez, Guillermo

2014-01-01

Worldwide dissemination of antibiotic resistance in bacteria is facilitated by plasmids that encode postsegregational killing (PSK) systems. These produce a stable toxin (T) and a labile antitoxin (A) conditioning cell survival to plasmid maintenance, because only this ensures neutralization of toxicity. Shortage of antibiotic alternatives and the link of TA pairs to PSK have stimulated the opinion that premature toxin activation could be used to kill these recalcitrant organisms in the clinic. However, validation of TA pairs as therapeutic targets requires unambiguous understanding of their mode of action, consequences for cell viability, and function in plasmids. Conflicting with widespread notions concerning these issues, we had proposed that the TA pair kis-kid (killing suppressor-killing determinant) might function as a plasmid rescue system and not as a PSK system, but this remained to be validated. Here, we aimed to clarify unsettled mechanistic aspects of Kid activation, and of the effects of this for kis-kid–bearing plasmids and their host cells. We confirm that activation of Kid occurs in cells that are about to lose the toxin-encoding plasmid, and we show that this provokes highly selective restriction of protein outputs that inhibits cell division temporarily, avoiding plasmid loss, and stimulates DNA replication, promoting plasmid rescue. Kis and Kid are conserved in plasmids encoding multiple antibiotic resistance genes, including extended spectrum β-lactamases, for which therapeutic options are scarce, and our findings advise against the activation of this TA pair to fight pathogens carrying these extrachromosomal DNAs. PMID:24449860

16. WEST ELEVATION. MONOMOY POINT LT. STATION, MASS., SHOWING PROPOSED ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

16. WEST ELEVATION. MONOMOY POINT LT. STATION, MASS., SHOWING PROPOSED ALTERATION AND IMPROVEMENT OF DWELLING. No. 1343. SHEET 3 of 5. July 1899. - Monomoy Point Light Station, Approximately 3500 feet Northeast Powder Hole Pond, Monomoy National Wildlife Refuge, Chatham, Barnstable County, MA

17. WEST ELEVATION. MONOMOY POINT LT. STATION, MASS., SHOWING PROPOSED ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

17. WEST ELEVATION. MONOMOY POINT LT. STATION, MASS., SHOWING PROPOSED ALTERATION AND IMPROVEMENT OF DWELLING. No. 1343. Sheet 4 of 5. July 1899. - Monomoy Point Light Station, Approximately 3500 feet Northeast Powder Hole Pond, Monomoy National Wildlife Refuge, Chatham, Barnstable County, MA

14. FIRST FLOOR PLAN. MONOMOY POINT LT. STATION, MASS., SHOWING ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

14. FIRST FLOOR PLAN. MONOMOY POINT LT. STATION, MASS., SHOWING PROPOSED ALTERATION AND IMPROVEMENT OF DWELLING. No. 1343. SHEET 1 of 5. July 1899. - Monomoy Point Light Station, Approximately 3500 feet Northeast Powder Hole Pond, Monomoy National Wildlife Refuge, Chatham, Barnstable County, MA

15. SECOND FLOOR PLAN. MONOMOY POINT LT. STATION, MASS., SHOWING ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

15. SECOND FLOOR PLAN. MONOMOY POINT LT. STATION, MASS., SHOWING PROPOSED ALTERATION AND IMPROVEMENT OF DWELLING. No. 1343. SHEET 2 OF 5. July 1899. - Monomoy Point Light Station, Approximately 3500 feet Northeast Powder Hole Pond, Monomoy National Wildlife Refuge, Chatham, Barnstable County, MA

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.

LT1SWTR Form for Conventional or Direct Filtration 10K

EPA Pesticide Factsheets

The LT1SWTR monthly report for turbidity and disinfection data contains the Daily Data Sheet for Combined Filter Effluent (CFE) Turbidity, Disinfectant Residual Data, and Individual Filter (IF) Turbidity Monitoring data.

Characterization of Alpha-Toxin hla Gene Variants, Alpha-Toxin Expression Levels, and Levels of Antibody to Alpha-Toxin in Hemodialysis and Postsurgical Patients with Staphylococcus aureus Bacteremia

PubMed Central

Wu, Yuling; Tabor, David E.; Mok, Hoyin; Sellman, Bret R.; Jenkins, Amy; Yu, Li; Jafri, Hasan S.; Rude, Thomas H.; Ruffin, Felicia; Schell, Wiley A.; Park, Lawrence P.; Yan, Qin; Thaden, Joshua T.; Messina, Julia A.; Esser, Mark T.

2014-01-01

Alpha-toxin is a major Staphylococcus aureus virulence factor. This study evaluated potential relationships between in vitro alpha-toxin expression of S. aureus bloodstream isolates, anti-alpha-toxin antibody in serum of patients with S. aureus bacteremia (SAB), and clinical outcomes in 100 hemodialysis and 100 postsurgical SAB patients. Isolates underwent spa typing and hla sequencing. Serum anti-alpha-toxin IgG and neutralizing antibody levels were measured by using an enzyme-linked immunosorbent assay and a red blood cell (RBC)-based hemolysis neutralization assay. Neutralization of alpha-toxin by an anti-alpha-toxin monoclonal antibody (MAb MEDI4893) was tested in an RBC-based lysis assay. Most isolates encoded hla (197/200; 98.5%) and expressed alpha-toxin (173/200; 86.5%). In vitro alpha-toxin levels were inversely associated with survival (cure, 2.19 μg/ml, versus failure, 1.09 μg/ml; P < 0.01). Both neutralizing (hemodialysis, 1.26 IU/ml, versus postsurgical, 0.95; P < 0.05) and IgG (hemodialysis, 1.94 IU/ml, versus postsurgical, 1.27; P < 0.05) antibody levels were higher in the hemodialysis population. Antibody levels were also significantly higher in patients infected with alpha-toxin-expressing S. aureus isolates (P < 0.05). Levels of both neutralizing antibodies and IgG were similar among patients who were cured and those not cured (failures). Sequence analysis of hla revealed 12 distinct hla genotypes, and all genotypic variants were susceptible to a neutralizing monoclonal antibody in clinical development (MEDI4893). These data demonstrate that alpha-toxin is highly conserved in clinical S. aureus isolates. Higher in vitro alpha-toxin levels were associated with a positive clinical outcome. Although patients infected with alpha-toxin-producing S. aureus exhibited higher anti-alpha-toxin antibody levels, these levels were not associated with a better clinical outcome in this study. PMID:25392350

Lymphocyte receptors for pertussis toxin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Clark, C.G.; Armstrong, G.D.

1990-12-01

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, andmore » 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.« less

Botulinum toxin: Bioweapon & magic drug

PubMed Central

Dhaked, Ram Kumar; Singh, Manglesh Kumar; Singh, Padma; Gupta, Pallavi

2010-01-01

Botulinum neurotoxins, causative agents of botulism in humans, are produced by Clostridium botulinum, an anaerobic spore-former Gram positive bacillus. Botulinum neurotoxin poses a major bioweapon threat because of its extreme potency and lethality; its ease of production, transport, and misuse; and the need for prolonged intensive care among affected persons. A single gram of crystalline toxin, evenly dispersed and inhaled, can kill more than one million people. The basis of the phenomenal potency of botulinum toxin is enzymatic; the toxin is a zinc proteinase that cleaves neuronal vesicle associated proteins responsible for acetylcholine release into the neuromuscular junction. As a military or terrorist weapon, botulinum toxin could be disseminated via aerosol or by contamination of water or food supplies, causing widespread casualties. A fascinating aspect of botulinum toxin research in recent years has been development of the most potent toxin into a molecule of significant therapeutic utility. It is the first biological toxin which is licensed for treatment of human diseases. In the late 1980s, Canada approved use of the toxin to treat strabismus, in 2001 in the removal of facial wrinkles and in 2002, the FDA in the United States followed suit. The present review focuses on both warfare potential and medical uses of botulinum neurotoxin. PMID:21149997

Botulinum toxin: bioweapon & magic drug.

PubMed

Dhaked, Ram Kumar; Singh, Manglesh Kumar; Singh, Padma; Gupta, Pallavi

2010-11-01

Botulinum neurotoxins, causative agents of botulism in humans, are produced by Clostridium botulinum, an anaerobic spore-former Gram positive bacillus. Botulinum neurotoxin poses a major bioweapon threat because of its extreme potency and lethality; its ease of production, transport, and misuse; and the need for prolonged intensive care among affected persons. A single gram of crystalline toxin, evenly dispersed and inhaled, can kill more than one million people. The basis of the phenomenal potency of botulinum toxin is enzymatic; the toxin is a zinc proteinase that cleaves neuronal vesicle associated proteins responsible for acetylcholine release into the neuromuscular junction. As a military or terrorist weapon, botulinum toxin could be disseminated via aerosol or by contamination of water or food supplies, causing widespread casualties. A fascinating aspect of botulinum toxin research in recent years has been development of the most potent toxin into a molecule of significant therapeutic utility . It is the first biological toxin which is licensed for treatment of human diseases. In the late 1980s, Canada approved use of the toxin to treat strabismus, in 2001 in the removal of facial wrinkles and in 2002, the FDA in the United States followed suit. The present review focuses on both warfare potential and medical uses of botulinum neurotoxin.

Topical botulinum toxin.

PubMed

Collins, Ashley; Nasir, Adnan

2010-03-01

Nanotechnology is a rapidly growing discipline that capitalizes on the unique properties of matter engineered on the nanoscale. Vehicles incorporating nanotechnology have led to great strides in drug delivery, allowing for increased active ingredient stability, bioavailability, and site-specific targeting. Botulinum toxin has historically been used for the correction of neurological and neuromuscular disorders, such as torticollis, blepharospasm, and strabismus. Recent dermatological indications have been for the management of axillary hyperhydrosis and facial rhytides. Traditional methods of botulinum toxin delivery have been needle-based. These have been associated with increased pain and cost. Newer methods of botulinum toxin formulation have yielded topical preparations that are bioactive in small pilot clinical studies. While there are some risks associated with topical delivery, the refinement and standardization of delivery systems and techniques for the topical administration of botulinum toxin using nanotechnology is anticipated in the near future.

18. EXISTING FIRST FLOOR PLAN. MONOMOY POINT LT. STATION, MASS., ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

18. EXISTING FIRST FLOOR PLAN. MONOMOY POINT LT. STATION, MASS., SHOWING PROPOSED ALTERATION AND IMPROVEMENT OF DWELLING. No. 1343. Sheet 5 of 5. July 1899. - Monomoy Point Light Station, Approximately 3500 feet Northeast Powder Hole Pond, Monomoy National Wildlife Refuge, Chatham, Barnstable County, MA

6-Shogaol has anti-amyloidogenic activity and ameliorates Alzheimer's disease via CysLT1R-mediated inhibition of cathepsin B.

PubMed

Na, Ji-Young; Song, Kibbeum; Lee, Ju-Woon; Kim, Sokho; Kwon, Jungkee

2016-08-12

Although 6-shogaol, a constituent of ginger, has been reported to have anti-inflammatory and anti-oxidant effects on neuronal cells, the effects of 6-shogaol on Alzheimer's disease (AD) have not yet been investigated. Here we aimed to determine whether 6-shogaol exerts neuroprotective effects against AD. Specifically, we investigated the effects of 6-shogaol on the cysteinyl leukotriene 1 receptor (CysLT1R), a major factor in AD pathogenesis. Moreover, we clarified the relationship between CysLT1R and cathepsin B, a cysteine protease. We used in vitro and in vivo models to determine whether 6-shogaol inhibits CysLT1R/cathepsin B in an amyloid-beta (Aβ; 1-42)-induced model of neurotoxicity. We first confirmed that CysLT1R and cathepsin B are upregulated by Aβ (1-42) and that CysLT1R activation induces cathepsin B. In contrast, we found that 6-shogaol-mediated inhibition of CysLT1R downregulates cathepsin B in both in vitro and in vivo models. Furthermore, we found that 6-shogaol-mediated inhibition of CysLT1R/cathepsin B reduces Aβ deposition in the brain and ameliorates behavioral deficits in APPSw/PS1-dE9 Tg mice. Our results indicate that 6-shogaol is a CysLT1R/cathepsin B inhibitor and is a novel potential therapeutic agent for the treatment of various neurodegenerative diseases, including AD. Copyright © 2016 Elsevier Inc. All rights reserved.

Detecting and discriminating among Shiga toxins

USDA-ARS?s Scientific Manuscript database

The virulence associated with Shiga toxin producing Escherichia coli (STEC) infections is from the Shiga toxins produced by the E. coli strain. Although Shiga toxins are associated with E. coli, the expression of the toxins is actually controlled by a temperate lambdoid phage that infects the host. ...

Assessment of the labile fractions of copper and zinc in marinas and port areas in Southern Brazil.

PubMed

Costa, Luiza Dy Fonseca; Wallner-Kersanach, Mônica

2013-08-01

The dissolved labile and labile particulate fractions (LPF) of Cu and Zn were analyzed during different seasons and salinity conditions in estuarine waters of marina, port, and shipyard areas in the southern region of the Patos Lagoon (RS, Brazil). The dissolved labile concentration was determined using the diffusive gradients in thin films technique (DGT). DGT devices were deployed in seven locations of the estuary for 72 h and the physicochemical parameters were also measured. The LPF of Cu and Zn was determined by daily filtering of water samples. Seasonal variation of DGT-Cu concentrations was only significant (p < 0.05) at one shipyard area, while DGT-Zn was significant (p < 0.05) in every locations. The LPF of Cu and Zn concentrations demonstrated seasonal and spatial variability in all locations, mainly at shipyard areas during high salinity conditions. In general, except the control location, the sampling locations showed mean variations of 0.11-0.45 μg L(-1) for DGT-Cu, 0.89-9.96 μg L(-1) for DGT-Zn, 0.65-3.69 μg g(-1) for LPF-Cu, and 1.35-10.87 μg g(-1) for LPF-Zn. Shipyard areas demonstrated the most expressive values of labile Cu and Zn in both fractions. Strong relationship between DGT-Zn and LPF-Zn was found suggesting that the DGT-Zn fraction originates from the suspended particulate matter. Water salinity and suspended particulate matter content indicated their importance for the control of the labile concentrations of Cu and Zn in the water column. These parameters must be taken into consideration for comparison among labile metals in estuaries.

Botulinum Toxin and Gastrointestinal Tract Disorders

PubMed Central

Weiser, Kirsten; Kennedy, Abigail

2008-01-01

The history of botulinum toxin is fascinating. First recognized as the cause of botulism nearly 200 years ago, it was originally feared as a deadly poison. Over the last 30 years, however, botulinum toxin has been transformed into a readily available medication used to treat a variety of medical disorders. Interest in the use of botulinum toxin has been particularly strong for patients with spastic smooth muscle disorders of the gastrointestinal tract. Patients with achalasia, diffuse esophageal spasm, gastroparesis, sphincter of Oddi dysfunction, and anal fissures have all been treated with botulinum toxin injections, often with impressive results. However, not all patients respond to botulinum toxin therapy, and large randomized controlled trials are lacking for many conditions commonly treated with botulinum toxin. This paper reviews the history, microbiology, and pharmacology of botulinum toxin, discusses its mechanism of action, and then presents recent evidence from the literature regarding the use of botulinum toxin for the treatment of a variety of gastrointestinal tract disorders. PMID:21960915

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.

Impact of temperamental mood lability on depressive mixed state.

PubMed

Benazzi, Franco

2006-01-01

Cyclothymic temperament (which includes mood lability) is common in bipolar II disorder (BP-II). Depressive mixed state (DMX), a major depressive episode (MDE) mixed with intra-episode hypomanic symptoms (3 or more, according to a recently validated definition), was found to be common in BP-II and not uncommon in major depressive disorder (MDD). The study aim was to find the impact of temperamental mood lability (TML) on DMX. Consecutive 148 BP-II and 117 MDD outpatients presenting for MDE treatment were interviewed by the Structured Clinical Interview for DSM-IV as modified by Benazzi and Akiskal to reduce the false negative BP-II. Intra-MDE hypomanic symptoms were systematically assessed. Kraepelin, Angst, and Akiskal's definitions of temperamental mood lability (i.e., frequent up and down fluctuations of mood between major mood episodes since young age) were followed. DMX was present in 61.5%, TML in 52.8%. In the DMX sample, TML was present in 57.6%, and in the non-DMX sample TML was present in 45.0% (OR = 1.6, 95% CI = 1.0-2.7). In the DMX sample, independent predictors of DMX with TML were BP-II and young age at onset. Intra-MDE hypomanic symptoms, and MDE, melancholic and atypical symptoms were not significantly different between DMX patients with TML and DMX patients without TML, apart from more temperamental interpersonal sensitivity in DMX patients with TML (OR = 2.0, 95% CI = 1.0-3.8). DMX patients with TML had a younger onset age, suggesting that TML may facilitate the onset of DMX or that it may be a precursor of DMX. The association of BP-II with DMX, TML, and interpersonal sensitivity can make the course of BP-II more unstable and its treatment more complex.

Pore-forming activity of clostridial binary toxins.

PubMed

Knapp, O; Benz, R; Popoff, M R

2016-03-01

Clostridial binary toxins (Clostridium perfringens Iota toxin, Clostridium difficile transferase, Clostridium spiroforme toxin, Clostridium botulinum C2 toxin) as Bacillus binary toxins, including Bacillus anthracis toxins consist of two independent proteins, one being the binding component which mediates the internalization into cell of the intracellularly active component. Clostridial binary toxins induce actin cytoskeleton disorganization through mono-ADP-ribosylation of globular actin and are responsible for enteric diseases. Clostridial and Bacillus binary toxins share structurally and functionally related binding components which recognize specific cell receptors, oligomerize, form pores in endocytic vesicle membrane, and mediate the transport of the enzymatic component into the cytosol. Binding components retain the global structure of pore-forming toxins (PFTs) from the cholesterol-dependent cytotoxin family such as perfringolysin. However, their pore-forming activity notably that of clostridial binding components is more related to that of heptameric PFT family including aerolysin and C. perfringens epsilon toxin. This review focuses upon pore-forming activity of clostridial binary toxins compared to other related PFTs. This article is part of a Special Issue entitled: Pore-Forming Toxins edited by Mauro Dalla Serra and Franco Gambale. Copyright © 2015 Elsevier B.V. All rights reserved.

Nanoscale characterization and local piezoelectric properties of lead-free KNN-LT-LS thin films

NASA Astrophysics Data System (ADS)

Abazari, M.; Choi, T.; Cheong, S.-W.; Safari, A.

2010-01-01

We report the observation of domain structure and piezoelectric properties of pure and Mn-doped (K0.44,Na0.52,Li0.04)(Nb0.84,Ta0.1,Sb0.06)O3 (KNN-LT-LS) thin films on SrTiO3 substrates. It is revealed that, using piezoresponse force microscopy, ferroelectric domain structure in such 500 nm thin films comprised of primarily 180° domains. This was in accordance with the tetragonal structure of the films, confirmed by relative permittivity measurements and x-ray diffraction patterns. Effective piezoelectric coefficient (d33) of the films were calculated using piezoelectric displacement curves and shown to be ~53 pm V-1 for pure KNN-LT-LS thin films. This value is among the highest values reported for an epitaxial lead-free thin film and shows a great potential for KNN-LT-LS to serve as an alternative to PZT thin films in future applications.

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 - guided botulinum toxin treatment; ...

Clostridium perfringens epsilon toxin: the third most potent bacterial toxin known.

PubMed

Alves, Guilherme Guerra; Machado de Ávila, Ricardo Andrez; Chávez-Olórtegui, Carlos Delfin; Lobato, Francisco Carlos Faria

2014-12-01

Epsilon toxin (ETX) is produced by Clostridium perfringens type B and D strains and causes enterotoxemia, a highly lethal disease with major impacts on the farming of domestic ruminants, particularly sheep. ETX belongs to the aerolysin-like pore-forming toxin family. Although ETX has striking similarities to other toxins in this family, ETX is often more potent, with an LD50 of 100 ng/kg in mice. Due to this high potency, ETX is considered as a potential bioterrorism agent and has been classified as a category B biological agent by the Centers for Disease Control and Prevention (CDC) of the United States. The protoxin is converted to an active toxin through proteolytic cleavage performed by specific proteases. ETX is absorbed and acts locally in the intestines then subsequently binds to and causes lesions in other organs, including the kidneys, lungs and brain. The importance of this toxin for veterinary medicine and its possible use as a biological weapon have drawn the attention of researchers and have led to a large number of studies investigating ETX. The aim of the present work is to review the existing knowledge on ETX from C. perfringens type B and D. Copyright © 2014 Elsevier Ltd. All rights reserved.

[Today's threat of ricin toxin].

PubMed

From, Sławomir; Płusa, Tadeusz

2015-09-01

Since the late 70s of the last century there were more than 700 incidents related to the use of the ricin toxin. For this reason, CDC (Center of Disease Control and Prevention) recognized toxin as a biological weapon category B. The lethal dose of ricin toxin after parenteral administration is 0.0001 mg/kg and after oral administration 0.2 mg. The first symptoms of poisoning occur within a few hours after application of toxin as a nausea, vomiting and abdominal pain. In the final stage there are observed: cardiac arrhythmia, collapse and symptoms suggestive of involvement of the central nervous system. Stage immediately preceding death is a state of coma. The ricin toxin is still the substance against which action has no optimal antidote. Developed a vaccine called RiVax is waiting for its registration. It should be pointed out that the availability of a ricin toxin makes it possible to use it for real bioterrorists. © 2015 MEDPRESS.

A common origin for the bacterial toxin-antitoxin systems parD and ccd, suggested by analyses of toxin/target and toxin/antitoxin interactions.

PubMed

Smith, Andrew B; López-Villarejo, Juan; Diago-Navarro, Elizabeth; Mitchenall, Lesley A; Barendregt, Arjan; Heck, Albert J; Lemonnier, Marc; Maxwell, Anthony; Díaz-Orejas, Ramón

2012-01-01

Bacterial toxin-antitoxin (TA) systems encode two proteins, a potent inhibitor of cell proliferation (toxin) and its specific antidote (antitoxin). Structural data has revealed striking similarities between the two model TA toxins CcdB, a DNA gyrase inhibitor encoded by the ccd system of plasmid F, and Kid, a site-specific endoribonuclease encoded by the parD system of plasmid R1. While a common structural fold seemed at odds with the two clearly different modes of action of these toxins, the possibility of functional crosstalk between the parD and ccd systems, which would further point to their common evolutionary origin, has not been documented. Here, we show that the cleavage of RNA and the inhibition of protein synthesis by the Kid toxin, two activities that are specifically counteracted by its cognate Kis antitoxin, are altered, but not inhibited, by the CcdA antitoxin. In addition, Kis was able to inhibit the stimulation of DNA gyrase-mediated cleavage of DNA by CcdB, albeit less efficiently than CcdA. We further show that physical interactions between the toxins and antitoxins of the different systems do occur and define the stoichiometry of the complexes formed. We found that CcdB did not degrade RNA nor did Kid have any reproducible effect on the tested DNA gyrase activities, suggesting that these toxins evolved to reach different, rather than common, cellular targets.

Purification of the Clostridium spiroforme binary toxin and activity of the toxin on HEp-2 cells.

PubMed

Popoff, M R; Milward, F W; Bancillon, B; Boquet, P

1989-08-01

The two components Sa (Mr, 44,000) and Sb (Mr, 92,000) of Clostridium spiroforme toxin were identified and characterized. Serological data permitted the identification of two groups of actin ADP-ribosylating clostridial toxins. The first consists of only C. botulinum C2. The second group includes spiroforme toxin, iota toxin of C. perfringens E, and an enzyme called CDT found in one strain of C. difficile, antibodies against which cross-react with all of the members of both groups. C. spiroforme toxin acted on cells by disrupting microfilaments by ADP-ribosylation of G actin. Toxicity was not blocked by 10 or 20 mM ammonium chloride and was only moderately inhibited by 30 mM NH4Cl. Inhibition of coated-pit formation in HEp-2 cells by potassium depletion strongly protected against the effect of C. spiroforme toxin. Toxicity was not blocked by incubation of HEp-2 cells and spiroforme toxin at 15 degrees C. These results suggest that this new binary toxin enters cells via the coated-pit-coated-vesicle pathway and might reach the cytoplasm at the same time as or before transfer to early endosomes.

Purification of the Clostridium spiroforme binary toxin and activity of the toxin on HEp-2 cells.

PubMed Central

Popoff, M R; Milward, F W; Bancillon, B; Boquet, P

1989-01-01

The two components Sa (Mr, 44,000) and Sb (Mr, 92,000) of Clostridium spiroforme toxin were identified and characterized. Serological data permitted the identification of two groups of actin ADP-ribosylating clostridial toxins. The first consists of only C. botulinum C2. The second group includes spiroforme toxin, iota toxin of C. perfringens E, and an enzyme called CDT found in one strain of C. difficile, antibodies against which cross-react with all of the members of both groups. C. spiroforme toxin acted on cells by disrupting microfilaments by ADP-ribosylation of G actin. Toxicity was not blocked by 10 or 20 mM ammonium chloride and was only moderately inhibited by 30 mM NH4Cl. Inhibition of coated-pit formation in HEp-2 cells by potassium depletion strongly protected against the effect of C. spiroforme toxin. Toxicity was not blocked by incubation of HEp-2 cells and spiroforme toxin at 15 degrees C. These results suggest that this new binary toxin enters cells via the coated-pit-coated-vesicle pathway and might reach the cytoplasm at the same time as or before transfer to early endosomes. Images PMID:2545625

Measurement of labile copper in wine by medium exchange stripping potentiometry utilising screen printed carbon electrodes.

PubMed

Clark, Andrew C; Kontoudakis, Nikolaos; Barril, Celia; Schmidtke, Leigh M; Scollary, Geoffrey R

2016-07-01

The presence of copper in wine is known to impact the reductive, oxidative and colloidal stability of wine, and techniques enabling measurement of different forms of copper in wine are of particular interest in understanding these spoilage processes. Electrochemical stripping techniques developed to date require significant pretreatment of wine, potentially disturbing the copper binding equilibria. A thin mercury film on a screen printed carbon electrode was utilised in a flow system for the direct analysis of labile copper in red and white wine by constant current stripping potentiometry with medium exchange. Under the optimised conditions, including an enrichment time of 500s and constant current of 1.0μA, the response range was linear from 0.015 to 0.200mg/L. The analysis of 52 red and white wines showed that this technique generally provided lower labile copper concentrations than reported for batch measurement by related techniques. Studies in a model system and in finished wines showed that the copper sulfide was not measured as labile copper, and that loss of hydrogen sulfide via volatilisation induced an increase in labile copper within the model wine system. Copyright © 2016 Elsevier B.V. All rights reserved.

Molecular cloning of a C-type lectin (LvLT) from the shrimp Litopenaeus vannamei: early gene down-regulation after WSSV infection.

PubMed

Ma, Tracy Hoi Tung; Tiu, Shirley Hiu Kwan; He, Jian-Guo; Chan, Siu-Ming

2007-08-01

C-type lectin is one of the pattern-recognition proteins of the non-self innate immune system in the invertebrates. In this study, a lectin-like cDNA (LvLT) of Litopenaeus vannamei was cloned and characterized. LvLT cDNA consists of 1035 nt encoding for a protein with 345 amino acid residues. The deduced LvLT consists of two putative carbohydrate-recognition domains (CRDs) as found in most C-type lectins. The first CRD consists of an amino acid motif (QPD) for the binding of galactose and the other CRDs consist of amino acid motifs (EPN) for the binding of mannose. Except for some conserved amino acid residues, the CRD of LvLT shared an overall low amino acid sequence identity with CRDs of other lectins. Unlike other shrimp lectins, LvLT is expressed only in the hepatopancreas but not in the hemocytes as revealed by RT-PCR. When juvenile shrimp were challenged with shrimp extracts containing white spot syndrome virus (WSSV), the expression levels of LvLT decreased initially in the first 2 h and then increased to a much higher level after 4 h. The results suggest that the initial reduction in LvLT transcript level may be related to the WSSV infection in shrimp.

Clostridium perfringens type A–E toxin plasmids

PubMed Central

Freedman, John C.; Theoret, James R.; Wisniewski, Jessica A.; Uzal, Francisco A.; Rood, Julian I.; McClane, Bruce A.

2014-01-01

Clostridium perfringens relies upon plasmid-encoded toxin genes to cause intestinal infections. These toxin genes are associated with insertion sequences that may facilitate their mobilization and transfer, giving rise to new toxin plasmids with common backbones. Most toxin plasmids carry a transfer of clostridial plasmids locus mediating conjugation, which likely explains the presence of similar toxin plasmids in otherwise unrelated C. perfringens strains. The association of many toxin genes with insertion sequences and conjugative plasmids provides virulence flexibility when causing intestinal infections. However, incompatibility issues apparently limit the number of toxin plasmids maintained by a single cell. PMID:25283728

THE PRODUCTION OF DIPHTHERIA TOXIN

PubMed Central

Park, W. H.; Williams, A. W.

1896-01-01

Toxin of sufficient strength to kill a 400-gramme guinea-pig in three days and a half in a dose of 0·cubic centimetre developed in suitable bouillon, contained in ordinary Erlenmeyer flasks, within a period of twenty-four hours. In such boullon the toxin reached its greatest strength in from four to seven days (0·005 cubic centimetre killing a 500-gramme guinea-pig in three days). This period of time covered that of the greatest growth of the bacilli, as shown both by the appearance of the culture and by the number of colonies developing an agar plates. The bodies of the diphtheria bacili did not at any time contain toxin in cosiderable amounts. The type of growth of the bacili and the rapidity and extent of the production of toxin depended more on the reaction of the bouillon than upon any other single factor. The best results were obtained in bouillon which, after being neutralized to litmus, had about seven cubic centimetres of normal soda solution added to each litre. An excessive amount of either acid or alkali prevented the development of toxin. Strong toxin was produced in bouillon containing peptone ranging from one to ten per cent. The strength of toxin averaged greater in the two and four-per-cent peptone solutions than in the one-percent. When the stage of acid reaction was brief and the degree of acidity probably slight, strong toxin developed while the culture bouillon was still acid; but when the stage of acid reaction was prolonged, little if any toxin was produced until just before the fluid became alkaline. Glucose is deleterious to the growth of the diphtheria bacillus and to the production of toxin when it is present in sufficient amounts to cause by its disintegration too great a degree of acidity in the fluid culture. When the acid resulting from decomposition of glucose is neutralized by the addition of alkali the diphtheria bacilus again grows abundantly. Glucose is not present, at least as a rule, in sufficient amounts in the meat as

[Intoxication of botulinum toxin].

PubMed

Chudzicka, Aleksandra

2015-09-01

Botulinum toxin is an egzotoxin produced by Gram positive bacteria Clostridium botulinum. It is among the most potent toxins known. The 3 main clinical presentations of botulism are as follows: foodborne botulism, infant botulism and wound botulism. The main symptom of intoxication is flat muscles paralysis. The treatment is supportive care and administration of antitoxin. In prevention the correct preparing of canned food is most important. Botulinum toxin is accepted as a biological weapon. © 2015 MEDPRESS.

Simultaneous quantification of soil phosphorus labile pool and desorption kinetics using DGTs and 3D-DIFS

NASA Astrophysics Data System (ADS)

Menezes-Blackburn, Daniel; Sun, Jiahui; Lehto, Niklas; Zhang, Hao; Stutter, Marc; Giles, Courtney D.; Darch, Tegan; George, Timothy S.; Shand, Charles; Lumsdon, David; Blackwell, Martin; Wearing, Catherine; Cooper, Patricia; Wendler, Renate; Brown, Lawrie; Haygarth, Philip M.

2017-04-01

The phosphorus (P) labile pool and desorption kinetics were simultaneously evaluated in ten representative UK soils using the technique of Diffusive gradients in thin films (DGT). The DGT-induced fluxes in soil and sediments model (DIFS) was fitted to the time series of DGT deployment (1h to 240h). The desorbable P concentration (labile P) was obtained by multiplying the fitted Kd by the soil solution P concentration obtained using Diffusive Equilibration in Thin Films (DET) devices. The labile P was then compared to several soil P extracts including Olsen P, Resin P, FeO-P and water extractable P, in order to assess if these analytical procedures can be used to represent the labile P across different soils. The Olsen P, commonly used as a representation of the soil labile P pool, overestimated the desorbable P concentration by a seven fold factor. The use of this approach for the quantification of soil P desorption kinetics parameters was somewhat unprecise, showing a wide range of equally valid solutions for the response of the system P equilibration time (Tc). Additionally, the performance of different DIFS model versions (1D, 2D and 3D) was compared. Although these models had a good fit to experimental DGT time series data, the fitted parameters showed a poor agreement between different model versions. The limitations of the DIFS model family are associated with the assumptions taken in the modelling approach and the 3D version is here considered to be the most precise among them.

Why do we study animal toxins?

PubMed Central

ZHANG, Yun

2015-01-01

Venom (toxins) is an important trait evolved along the evolutionary tree of animals. Our knowledges on venoms, such as their origins and loss, the biological relevance and the coevolutionary patterns with other organisms are greatly helpful in understanding many fundamental biological questions, i.e., the environmental adaptation and survival competition, the evolution shaped development and balance of venoms, and the sophisticated correlations among venom, immunity, body power, intelligence, their genetic basis, inherent association, as well as the cost-benefit and trade-offs of biological economy. Lethal animal envenomation can be found worldwide. However, from foe to friend, toxin studies have led lots of important discoveries and exciting avenues in deciphering and fighting human diseases, including the works awarded the Nobel Prize and lots of key clinic therapeutics. According to our survey, so far, only less than 0.1% of the toxins of the venomous animals in China have been explored. We emphasize on the similarities shared by venom and immune systems, as well as the studies of toxin knowledge-based physiological toxin-like proteins/peptides (TLPs). We propose the natural pairing hypothesis. Evolution links toxins with humans. Our mission is to find out the right natural pairings and interactions of our body elements with toxins, and with endogenous toxin-like molecules. Although, in nature, toxins may endanger human lives, but from a philosophical point of view, knowing them well is an effective way to better understand ourselves. So, this is why we study toxins. PMID:26228472

Development and Lability in the Parent-Child Relationship During Adolescence: Associations With Pubertal Timing and Tempo

PubMed Central

Marceau, Kristine; Ram, Nilam; Susman, Elizabeth

2014-01-01

Adolescents' and parents' reactions to pubertal development are hypothesized to contribute to changes in family dynamics. Using 7-year longitudinal data from the NICHD-SECCYD (488 boys, 475 girls) we examined relations between pubertal development (timing, tempo) and trajectories (developmental change and year-to-year lability) of parent-child conflict and closeness from age 8.5 to 15.5 years. Changes were mostly characterized by year-to-year fluctuations – lability. Parent-child conflict increased and closeness decreased some with age. Pubertal timing and tempo were more consistently associated with lability in parent-child relationships than with long-term trends, although faster tempo was associated with steeper decreases in parent-child closeness. Findings provide a platform for examining how puberty contributes to both long-term and transient changes in adolescents' relationships and adjustment. PMID:26321856

Use of sunlight to partially detoxify groundnut (peanut) cake flour and casein contaminated with aflatoxin B1.

PubMed

Shantha, T; Murthy, V S

1981-03-01

Sunlight destroyed 83 and 50% of the toxin added to casein and groundnut cake flour, respectively. Equilibrium dialysis revealed that both casein and groundnut protein bind aflatoxin but the toxin bound to casein appeared more photo-labile than that bound to groundnut protein.

Immunogenicity of recombinant LT-B delivered orally to humans in transgenic corn.

PubMed

Tacket, Carol O; Pasetti, Marcela F; Edelman, Robert; Howard, John A; Streatfield, Stephen

2004-10-22

Previous clinical studies have demonstrated the feasibility of using edible transgenic plants to deliver protective antigens as new oral vaccines. Transgenic corn is particularly attractive for this purpose since the recombinant antigen is stable and homogeneous, and corn can be formulated in several edible forms without destroying the cloned antigen. Transgenic corn expressing 1 mg of LT-B of Escherichia coli without buffer was fed to adult volunteers in three doses, each consisting of 2.1 g of plant material. Seven (78%) of nine volunteers developed rises in both serum IgG anti-LT and numbers of specific antibody secreting cells after vaccination. Four (44%) of nine volunteers also developed stool IgA. Transgenic plants represent a new vector for oral vaccine antigens.

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

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.

A Common Origin for the Bacterial Toxin-Antitoxin Systems parD and ccd, Suggested by Analyses of Toxin/Target and Toxin/Antitoxin Interactions

PubMed Central

Mitchenall, Lesley A.; Barendregt, Arjan; Heck, Albert J.; Lemonnier, Marc; Maxwell, Anthony; Díaz-Orejas, Ramón

2012-01-01

Bacterial toxin-antitoxin (TA) systems encode two proteins, a potent inhibitor of cell proliferation (toxin) and its specific antidote (antitoxin). Structural data has revealed striking similarities between the two model TA toxins CcdB, a DNA gyrase inhibitor encoded by the ccd system of plasmid F, and Kid, a site-specific endoribonuclease encoded by the parD system of plasmid R1. While a common structural fold seemed at odds with the two clearly different modes of action of these toxins, the possibility of functional crosstalk between the parD and ccd systems, which would further point to their common evolutionary origin, has not been documented. Here, we show that the cleavage of RNA and the inhibition of protein synthesis by the Kid toxin, two activities that are specifically counteracted by its cognate Kis antitoxin, are altered, but not inhibited, by the CcdA antitoxin. In addition, Kis was able to inhibit the stimulation of DNA gyrase-mediated cleavage of DNA by CcdB, albeit less efficiently than CcdA. We further show that physical interactions between the toxins and antitoxins of the different systems do occur and define the stoichiometry of the complexes formed. We found that CcdB did not degrade RNA nor did Kid have any reproducible effect on the tested DNA gyrase activities, suggesting that these toxins evolved to reach different, rather than common, cellular targets. PMID:23029540

Bordetella Adenylate Cyclase-Hemolysin Toxins

PubMed Central

Guiso, Nicole

2017-01-01

Adenylate cyclase-hemolysin toxin is secreted and produced by three classical species of the genus Bordetella: Bordetella pertussis, B. parapertussis and B. bronchiseptica. This toxin has several properties such as: (i) adenylate cyclase activity, enhanced after interaction with the eukaryotic protein, calmodulin; (ii) a pore-forming activity; (iii) an invasive activity. It plays an important role in the pathogenesis of these Bordetella species responsible for whooping cough in humans or persistent respiratory infections in mammals, by modulating host immune responses. In contrast with other Bordetella toxins or adhesins, lack of (or very low polymorphism) is observed in the structural gene encoding this toxin, supporting its importance as well as a potential role as a vaccine antigen against whooping cough. In this article, an overview of the investigations undertaken on this toxin is presented. PMID:28892012

Pore-forming toxins in Cnidaria.

PubMed

Podobnik, Marjetka; Anderluh, Gregor

2017-12-01

The ancient phylum of Cnidaria contains many aquatic species with peculiar lifestyle. In order to survive, these organisms have evolved attack and defense mechanisms that are enabled by specialized cells and highly developed venoms. Pore-forming toxins are an important part of their venomous arsenal. Along some other types, the most representative are examples of four protein families that are commonly found in other kingdoms of life: actinoporins, Cry-like proteins, aerolysin-like toxins and MACPF/CDC toxins. Some of the homologues of pore-forming toxins may serve other functions, such as in food digestion, development and response against pathogenic organisms. Due to their interesting physico-chemical properties, the cnidarian pore-forming toxins may also serve as tools in medical research and nanobiotechnological applications. Copyright © 2017 Elsevier Ltd. All rights reserved.

Plant Insecticidal Toxins in Ecological Networks

PubMed Central

Ibanez, Sébastien; Gallet, Christiane; Després, Laurence

2012-01-01

Plant secondary metabolites play a key role in plant-insect interactions, whether constitutive or induced, C- or N-based. Anti-herbivore defences against insects can act as repellents, deterrents, growth inhibitors or cause direct mortality. In turn, insects have evolved a variety of strategies to act against plant toxins, e.g., avoidance, excretion, sequestration and degradation of the toxin, eventually leading to a co-evolutionary arms race between insects and plants and to co-diversification. Anti-herbivore defences also negatively impact mutualistic partners, possibly leading to an ecological cost of toxin production. However, in other cases toxins can also be used by plants involved in mutualistic interactions to exclude inadequate partners and to modify the cost/benefit ratio of mutualism to their advantage. When considering the whole community, toxins have an effect at many trophic levels. Aposematic insects sequester toxins to defend themselves against predators. Depending on the ecological context, toxins can either increase insects’ vulnerability to parasitoids and entomopathogens or protect them, eventually leading to self-medication. We conclude that studying the community-level impacts of plant toxins can provide new insights into the synthesis between community and evolutionary ecology. PMID:22606374

*CYANOBACTERIA AND THEIR TOXINS

EPA Science Inventory

Cyanobacteria, or blue-green algae, are naturally-occurring contaminants of surface waters worldwide. These photosynthesizing prokaryotes thrive in warm, shallow, nutrient-rich waters. Many produce potent toxins as secondary metabolites. Cyanobacteria toxins have been document...

Sensitivity-enhanced detection of non-labile proton and carbon NMR spectra on water resonances.

PubMed

Novakovic, Mihajlo; Martinho, Ricardo P; Olsen, Gregory L; Lustig, Michael S; Frydman, Lucio

2017-12-20

Chemical exchange saturation transfer (CEST) experiments enhance the NMR signals of labile protons by continuously transferring these protons' saturation to an abundant solvent pool like water. The present study expands these principles by fusing into these experiments homonuclear isotropic mixing sequences, enabling the water-enhanced detection of non-exchangeable species. Further opportunities are opened by the addition of coupling-mediated heteronuclear polarization transfers, which then impose on the water resonance a saturation stemming from non-labile heteronuclear species like 13 C. To multiplex the ensuing experiments, these relayed approaches are combined with time-domain schemes involving multiple Ramsey-labeling experiments imparting the frequencies of the non-labile sites on the water resonance, via chemical exchange. 13 C and 1 H NMR spectra were detected in this fashion with about two-fold SNR amplification vis-à-vis conventionally detected spectroscopies. When combined with non-uniform sampling principles, this methodology thus becomes a sensitive alternative to detect non-exchangeable species in biomolecules. Still, multiple parameters including the scalar couplings and solvent exchange rates, will affect the efficiency and consequently the practicality of the overall experiment.

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

2015-03-01

From 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.

Prevalence of multi-antimicrobial-agent resistant, shiga toxin and enterotoxin producing Escherichia coli in surface waters of river Ganga.

PubMed

Ram, Siya; Vajpayee, Poornima; Shanker, Rishi

2007-11-01

The consumption of polluted surface water for domestic and recreational purposes by large populations in developing nations is a major cause of diarrheal disease related mortality. The river Ganga and its tributaries meet 40% of the water requirement for drinking and irrigation in India. In this study, Escherichia coli isolates (n=75) of the river Ganga water were investigated for resistance to antimicrobial agents (n=15) and virulence genes specific to shiga toxin (STEC) and enterotoxin producing E. coli (ETEC). E. coli isolates from the river Ganga water exhibit resistance to multiple antimicrobial agents. The distribution of antimicrobial agent resistance in E. colivaries significantly (chi2: 81.28 at df = 24, p < 0.001) between the sites. Both stx1 and stx2 genes were present in 82.3% of STEC (n=17) while remaining isolates possess either stxl (11.8%) or stx2 (5.9%). The presence of eaeA, hlyA, and chuA genes was observed in 70.6, 88.2, and 58.8% of STEC, respectively. Both LT1 and ST1 genes were positive in 66.7% of ETEC (n=15) while 33.3% of isolates harbor only LT1 gene. The prevalence of multi-antimicrobial-agent resistant E. coli in the river Ganga water poses increased risk of infections in the human population.

Food toxin detection with atomic force microscope

USDA-ARS?s Scientific Manuscript database

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...

Substrate lability and plant activity controls greenhouse gas release from Neotropical peatland

NASA Astrophysics Data System (ADS)

Sjogersten, Sofie; Hoyos, Jorge; Lomax, Barry; Turner, Ben; Wright, Emma

2014-05-01

Almost one third of global CO2 emissions resulting from land use change and substantial CH4 emissions originate from tropical peatlands. However, our understanding of the controls of CO2 and CH4 release from tropical peatlands are limited. The aim of this study was to investigate the role of peat lability and the activity of the vegetation on gas release using a combination of field and laboratory experiments. We demonstrated that peat lability constrained CH4 production to the surface peat under anaerobic conditions. The presence of plants shifted the C balance from a C source to a C sink with respect to CO2 while the activity of the root system strongly influenced CH4 emissions through its impact on soil O2 inputs. Both field and laboratory data suggest a coupling between the photosynthetic activity of the vegetation and the release of both CO2 and CH4 following the circadian rhythm of the dominant plant functional types. Forest clearance for agriculture resulted in elevated CH4 release, which we attribute in part to the cessation of root O2 inputs to the peat. We conclude that high emissions of CO2 and CH4 from forested tropical peatlands are likely driven by labile C inputs from the vegetation but that root O2 release may limit CH4 emissions.

Estimating labile particulate iron concentrations in coastal waters from remote sensing data

NASA Astrophysics Data System (ADS)

McGaraghan, Anna R.; Kudela, Raphael M.

2012-02-01

Owing to the difficulties inherent in measuring trace metals and the importance of iron as a limiting nutrient for biological systems, the ability to monitor particulate iron concentration remotely is desirable. This study examines the relationship between labile particulate iron, described here as weak acid leachable particulate iron or total dissolvable iron, and easily obtained bio-optical measurements. We develop a bio-optical proxy that can be used to estimate large-scale patterns of labile iron concentrations in surface waters, and we extend this by including other environmental variables in a multiple linear regression statistical model. By utilizing a ratio of optical backscatter and fluorescence obtained by satellite, we identify patterns in iron concentrations confirmed by traditional shipboard sampling. This basic relationship is improved with the addition of other environmental parameters in the statistical linear regression model. The optical proxy detects known temporal and spatial trends in average surface iron concentrations in Monterey Bay. The proxy is robust in that similar performance was obtained using two independent particulate iron data sets, but it exhibits weaker correlations than the full statistical model. This proxy will be a valuable tool for oceanographers seeking to monitor iron concentrations in coastal regions and allows for better understanding of the variability of labile particulate iron in surface waters to complement direct measurement of leachable particulate or total dissolvable iron.

The Interactions of Human Neutrophils with Shiga Toxins and Related Plant Toxins: Danger or Safety?

PubMed Central

Brigotti, Maurizio

2012-01-01

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

Constraining Dust Hazes at the L/T Transition via Variability

NASA Astrophysics Data System (ADS)

Radigan, Jacqueline; Apai, Daniel; Yang, Hao; Hiranaka, Kay; Cruz, Kelle; Buenzli, Esther; Marley, Mark

2014-12-01

The T2 dwarf SIMP 1629+03 is a variable L/T transition dwarf, with a normal near-infrared spectrum. However, it is remarkable in that the wavelength dependence of its variability differs markedly from that of other L/T transition brown dwarfs. In particular, the absence of a water absorption feature in its variability spectrum indicates that a patchy, high-altitude haze, rather than a deeper cloud layer is responsible for the observed variations. We propose to obtain Spitzer+HST observations of SIMP1629+02 over two consecutive rotations periods in order to simultaneously map it?s spectral variability across 1-5 um. The wide wavelength coverage will provide a suitable lever-arm for constraining the particle size distribution in the haze. A truly flat spectrum across this wavelength range would indicate large particle sizes in comparison to those inferred for red L-dwarf hazes, and would therefore provide direct evidence of grain growth with decreasing effective temperature and/or a grain-size dependence on surface gravity in brown dwarf atmospheres.

Cellular Entry of Clostridium perfringens Iota-Toxin and Clostridium botulinum C2 Toxin.

PubMed

Takehara, Masaya; Takagishi, Teruhisa; Seike, Soshi; Oda, Masataka; Sakaguchi, Yoshihiko; Hisatsune, Junzo; Ochi, Sadayuki; Kobayashi, Keiko; Nagahama, Masahiro

2017-08-11

Clostridium perfringens iota-toxin and Clostridium botulinum C2 toxin are composed of two non-linked proteins, one being the enzymatic component and the other being the binding/translocation component. These latter components recognize specific receptors and oligomerize in plasma membrane lipid-rafts, mediating the uptake of the enzymatic component into the cytosol. Enzymatic components induce actin cytoskeleton disorganization through the ADP-ribosylation of actin and are responsible for cell rounding and death. This review focuses upon the recent advances in cellular internalization of clostridial binary toxins.

Conditional Toxin Splicing Using a Split Intein System.

PubMed

Alford, Spencer C; O'Sullivan, Connor; Howard, Perry L

2017-01-01

Protein toxin splicing mediated by split inteins can be used as a strategy for conditional cell ablation. The approach requires artificial fragmentation of a potent protein toxin and tethering each toxin fragment to a split intein fragment. The toxin-intein fragments are, in turn, fused to dimerization domains, such that addition of a dimerizing agent reconstitutes the split intein. These chimeric toxin-intein fusions remain nontoxic until the dimerizer is added, resulting in activation of intein splicing and ligation of toxin fragments to form an active toxin. Considerations for the engineering and implementation of conditional toxin splicing (CTS) systems include: choice of toxin split site, split site (extein) chemistry, and temperature sensitivity. The following method outlines design criteria and implementation notes for CTS using a previously engineered system for splicing a toxin called sarcin, as well as for developing alternative CTS systems.

Mutant with diphtheria toxin receptor and acidification function but defective in entry of toxin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kohno, Kenji; Hayes, H.; Mekada, Eisuke

1987-09-01

A mutant of Chinese hamster ovary cells, GE1, that is highly resistant to diphtheria toxin was isolated. The mutant contains 50% ADP-ribosylatable elongation factor 2, but its protein synthesis was not inhibited by the toxin even at concentrations above 100 {mu}g/ml. {sup 125}I-labeled diphtheria toxin was associated with GE1 cells as well as with the parent cells but did not block protein synthesis of GE1 cells even when the cells were exposed to low pH in the presence or absence of NH{sub 4}Cl. The infections of GE1 cells and the parent cells by vesicular stomatitis virus were similar. GE1 cellsmore » were cross-resistant to Pseudomonas aeruginosa exotoxin A and so were about 1,000 times more resistant to this toxin than the parent cells. Hybrids of GE1 cells and the parent cells or mutant cells lacking a functional receptor were more sensitive to diphtheria toxin than GE1 cells. These results suggest that entry of diphtheria toxin into cells requires a cellular factor(s) in addition to those involved in receptor function and acidification of endosomes and that GE1 cells do not express this cellular factor. This character is recessive in GE1 cells.« less

Computational Studies of Snake Venom Toxins

PubMed Central

Ojeda, Paola G.; Caballero, Julio; Kaas, Quentin; González, Wendy

2017-01-01

Most snake venom toxins are proteins, and participate to envenomation through a diverse array of bioactivities, such as bleeding, inflammation, and pain, cytotoxic, cardiotoxic or neurotoxic effects. The venom of a single snake species contains hundreds of toxins, and the venoms of the 725 species of venomous snakes represent a large pool of potentially bioactive proteins. Despite considerable discovery efforts, most of the snake venom toxins are still uncharacterized. Modern bioinformatics tools have been recently developed to mine snake venoms, helping focus experimental research on the most potentially interesting toxins. Some computational techniques predict toxin molecular targets, and the binding mode to these targets. This review gives an overview of current knowledge on the ~2200 sequences, and more than 400 three-dimensional structures of snake toxins deposited in public repositories, as well as of molecular modeling studies of the interaction between these toxins and their molecular targets. We also describe how modern bioinformatics have been used to study the snake venom protein phospholipase A2, the small basic myotoxin Crotamine, and the three-finger peptide Mambalgin. PMID:29271884

In situ Identification of Labile Precursor Compounds and their Short-lived Intermediates in Plants using in vivo Nanospray High-resolution Mass Spectrometry.

PubMed

Chang, Qing; Peng, Yue'e; Shi, Bin; Dan, Conghui; Yang, Yijun; Shuai, Qin

2016-05-01

Many secondary metabolites in plants are labile compounds which under environmental stress, are difficult to detect and track due to the lack of rapid in situ identification techniques, making plant metabolomics research difficult. Therefore, developing a reliable analytical method for rapid in situ identification of labile compounds and their short-lived intermediates in plants is of great importance. To develop under atmospheric pressure, a rapid in situ method for effective identification of labile compounds and their short-lived intermediates in fresh plants. An in vivo nanospray high-resolution mass spectrometry (HR-MS) method was used for rapid capture of labile compounds and their short-lived intermediates in plants. A quartz capillary was partially inserted into fresh plant tissues, and the liquid flowed out through the capillary tube owing to the capillary effect. A high direct current (d.c.) voltage was applied to the plant to generate a spray of charged droplets from the tip of the capillary carrying bioactive molecules toward the inlet of mass spectrometer for full-scan and MS/MS analysis. Many labile compounds and short-lived intermediates were identified via this method: including glucosinolates and their short-lived intermediates (existing for only 10 s) in Raphanus sativus roots, alliin and its conversion intermediate (existing for 20 s) in Allium sativum and labile precursor compound chlorogenic acid in Malus pumila Mill. The method is an effective approach for in situ identification of internal labile compounds and their short-lived intermediates in fresh plants and it can be used as an auxiliary tool to explore the degradation mechanisms of new labile plant compounds. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Clostridial toxins active locally in the gastrointestinal tract.

PubMed

Wilkins, T; Krivan, H; Stiles, B; Carman, R; Lyerly, D

1985-01-01

Clostridium difficile and Clostridium spiroforme have only in recent years been recognized as intestinal pathogens. They both produce toxins that are also produced by other clostridia. C. difficile toxins A and B are produced by C. sordellii and a few strains of C. perfringens whereas C. spiroforme produces the same toxins as C. perfringens Type E (iota toxin). Iota toxin activity may be the product of two proteins. Toxigenic strains of C. spiroforme and Type E produce two antigens which possess much more biological activity when administered together than when given alone. C. difficile was thought for some time to produce only a single toxin, but then the enterotoxic activity was shown to be due to a separate toxin (toxin A). This toxin increases the oral toxicity of toxin B (the main cytotoxin) and may increase the permeability of the colon. Toxin A binds to a specific receptor in hamster brush border membranes and in the membranes of rabbit erythrocytes. This receptor appears to be a glycoprotein. The receptor can be extracted from the membrane with Triton and binds to immobilized toxin A. The receptor can be extracted and used to coat plastic plates as a first phase in an ELISA assay. Another assay has been developed in which the toxin A binds to the red cells and then the erythrocytes are agglutinated with antitoxin. An even more sensitive assay consists of using rabbit erythrocyte ghosts to bind the toxin and then precipitating the ghosts with antibody to toxin A attached to latex beads. Monoclonal antibodies to toxin A also have been developed and are used in these and other assays.

OBR-1-1/Fizika-LT(Letaushaya Tarelka/Flying Disk) experiment

NASA Image and Video Library

2009-04-24

ISS019-E-010226 (24 April 2009) --- Cosmonaut Gennady Padalka, Expedition 19/20 commander, holds the OBR-1-1/?Fizika-LT? (Letaushaya Tarelka/Flying Disk) educational experiment, also called ?UFO?, in the Zvezda Service Module of the International Space Station. The OBR-1-1 is part of the OBRAZOVANIE (Education) suite of three educational demonstrations of physics in microgravity.

Brown spider dermonecrotic toxin directly induces nephrotoxicity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chaim, Olga Meiri; Sade, Youssef Bacila; Bertoni da Silveira, Rafael

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 proteinaceousmore » 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

Cellular Entry of Clostridium perfringens Iota-Toxin and Clostridium botulinum C2 Toxin

PubMed Central

Takehara, Masaya; Takagishi, Teruhisa; Seike, Soshi; Oda, Masataka; Sakaguchi, Yoshihiko; Hisatsune, Junzo; Ochi, Sadayuki; Kobayashi, Keiko; Nagahama, Masahiro

2017-01-01

Clostridium perfringens iota-toxin and Clostridium botulinum C2 toxin are composed of two non-linked proteins, one being the enzymatic component and the other being the binding/translocation component. These latter components recognize specific receptors and oligomerize in plasma membrane lipid-rafts, mediating the uptake of the enzymatic component into the cytosol. Enzymatic components induce actin cytoskeleton disorganization through the ADP-ribosylation of actin and are responsible for cell rounding and death. This review focuses upon the recent advances in cellular internalization of clostridial binary toxins. PMID:28800062

[Character of brain interhemispheric relation in children at forming labile arterial hypertension].

PubMed

Koroleva, N V; Kolesnikov, S I; Bugun, O V; Dolgikh, V V

2010-01-01

Electroencephalography investigations were carried out twice in 26 schoolchildren in the age of 7-8 years and in the age of 9-10 years. The control group included healthy children: the research group included children in whom in the age of 7-8 years the normal level of arterial pressure was registered, and in whom in the age of 9-10 years labile arterial hypertension was revealed. It is revealed, that in children of younger school age forming of the labile form of arterial hypertension is connected whit infringement of processes of age changes of intercortical and cortical-subcortical interrelations and forming of rigidly integrated system of interhemispheric relations. Its mechanism of realization is carried out due to hyperactivation of the right hemisphere and it is incorporated on preclinical stage.

EGA Protects Mammalian Cells from Clostridium difficile CDT, Clostridium perfringens Iota Toxin and Clostridium botulinum C2 Toxin

PubMed Central

Schnell, Leonie; Mittler, Ann-Katrin; Sadi, Mirko; Popoff, Michel R.; Schwan, Carsten; Aktories, Klaus; Mattarei, Andrea; Tehran, Domenico Azarnia; Montecucco, Cesare; Barth, Holger

2016-01-01

The pathogenic bacteria Clostridium difficile, Clostridium perfringens and Clostridium botulinum produce the binary actin ADP-ribosylating toxins CDT, iota and C2, respectively. These toxins are composed of a transport component (B) and a separate enzyme component (A). When both components assemble on the surface of mammalian target cells, the B components mediate the entry of the A components via endosomes into the cytosol. Here, the A components ADP-ribosylate G-actin, resulting in depolymerization of F-actin, cell-rounding and eventually death. In the present study, we demonstrate that 4-bromobenzaldehyde N-(2,6-dimethylphenyl)semicarbazone (EGA), a compound that protects cells from multiple toxins and viruses, also protects different mammalian epithelial cells from all three binary actin ADP-ribosylating toxins. In contrast, EGA did not inhibit the intoxication of cells with Clostridium difficile toxins A and B, indicating a possible different entry route for this toxin. EGA does not affect either the binding of the C2 toxin to the cells surface or the enzyme activity of the A components of CDT, iota and C2, suggesting that this compound interferes with cellular uptake of the toxins. Moreover, for C2 toxin, we demonstrated that EGA inhibits the pH-dependent transport of the A component across cell membranes. EGA is not cytotoxic, and therefore, we propose it as a lead compound for the development of novel pharmacological inhibitors against clostridial binary actin ADP-ribosylating toxins. PMID:27043629

EGA Protects Mammalian Cells from Clostridium difficile CDT, Clostridium perfringens Iota Toxin and Clostridium botulinum C2 Toxin.

PubMed

Schnell, Leonie; Mittler, Ann-Katrin; Sadi, Mirko; Popoff, Michel R; Schwan, Carsten; Aktories, Klaus; Mattarei, Andrea; Azarnia Tehran, Domenico; Montecucco, Cesare; Barth, Holger

2016-04-01

The pathogenic bacteria Clostridium difficile, Clostridium perfringens and Clostridium botulinum produce the binary actin ADP-ribosylating toxins CDT, iota and C2, respectively. These toxins are composed of a transport component (B) and a separate enzyme component (A). When both components assemble on the surface of mammalian target cells, the B components mediate the entry of the A components via endosomes into the cytosol. Here, the A components ADP-ribosylate G-actin, resulting in depolymerization of F-actin, cell-rounding and eventually death. In the present study, we demonstrate that 4-bromobenzaldehyde N-(2,6-dimethylphenyl)semicarbazone (EGA), a compound that protects cells from multiple toxins and viruses, also protects different mammalian epithelial cells from all three binary actin ADP-ribosylating toxins. In contrast, EGA did not inhibit the intoxication of cells with Clostridium difficile toxins A and B, indicating a possible different entry route for this toxin. EGA does not affect either the binding of the C2 toxin to the cells surface or the enzyme activity of the A components of CDT, iota and C2, suggesting that this compound interferes with cellular uptake of the toxins. Moreover, for C2 toxin, we demonstrated that EGA inhibits the pH-dependent transport of the A component across cell membranes. EGA is not cytotoxic, and therefore, we propose it as a lead compound for the development of novel pharmacological inhibitors against clostridial binary actin ADP-ribosylating toxins.

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

[Biological and toxin terrorism weapons].

PubMed

Bokan, Slavko

2003-03-01

The use of biological agents and toxins in warfare and terrorism has a long history. Human, animal and plant pathogens and toxins can cause disease and can be used as a threat to humans, animals and staple crops. The same is true for biological agents. Although the use of biological agents and toxins in military conflicts has been a concern of military communities for many years, several recent events have increased the awareness of terrorist use of these weapons against civilian population. A Mass Casualty Biological (Toxin) Weapon (MCBTW) is any biological and toxin weapon capable of causing death or disease on a large scale, such that the military or civilian infrastructure of the state or organization being attacked is overwhelmed. A militarily significant (or terrorist) weapon is any weapon capable of affecting, directly or indirectly, that is physically or psychologically, the outcome of a military operation. Although many biological agents such as toxins and bioregulators can be used to cause diseases, there are only a few that can truly threaten civilian populations on a large scale. Bioregulators or modulators are biochemical compounds, such as peptides, that occur naturally in organisms. They are new class of weapons that can damage nervous system, alter moods, trigger psychological changes and kill. The potential military or terrorist use of bioregulators is similar to that of toxins. Some of these compounds are several hundred times more potent than traditional chemical warfare agents. Important features and military advantages of new bioregulators are novel sites of toxic action; rapid and specific effects; penetration of protective filters and equipment, and militarily effective physical incapacitation. This overview of biological agents and toxins is largely intended to help healthcare providers on all levels to make decisions in protecting general population from these agents.

Improving the method of low-temperature anisotropy of magnetic susceptibility (LT-AMS) measurements in air

NASA Astrophysics Data System (ADS)

Issachar, R.; Levi, T.; Lyakhovsky, V.; Marco, S.; Weinberger, R.

2016-07-01

This study examines the limitations of the method of low-temperature anisotropy of magnetic susceptibility (LT-AMS) measurements in air and presents technical improvements that significantly reduce the instrumental drift and measurement errors. We analyzed the temperature profile of porous chalk core after cooling in liquid nitrogen and found that the average temperature of the sample during the LT-AMS measurement in air is higher than 77K and close to 92K. This analysis indicates that the susceptibility of the paramagnetic minerals are amplified by a factor ˜3.2 relative to that of room temperature AMS (RT-AMS). In addition, it was found that liquid nitrogen was absorbed in the samples during immersing and contributed diamagnetic component of ˜-9 × 10-6 SI to the total mean susceptibility. We showed that silicone sheet placed around and at the bottom of the measuring coil is an effective thermal protection, preventing instrument drift by the cold sample. In this way, the measuring errors of LT-AMS reduced to the level of RT-AMS, allowing accurate comparison with standard AMS measurements. We examined the applicability of the LT-AMS measurements on chalk samples that consist <5% (weight) of paramagnetic minerals and showed that it helps to efficiently enhance the paramagnetic fabric. The present study offers a practical approach, which can be applied to various types of rocks to better delineate the paramagnetic phase using conventional equipment.

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

SVM-Based Prediction of Propeptide Cleavage Sites in Spider Toxins Identifies Toxin Innovation in an Australian Tarantula

PubMed Central

Wong, Emily S. W.; Hardy, Margaret C.; Wood, David; Bailey, Timothy; King, Glenn F.

2013-01-01

Spider neurotoxins are commonly used as pharmacological tools and are a popular source of novel compounds with therapeutic and agrochemical potential. Since venom peptides are inherently toxic, the host spider must employ strategies to avoid adverse effects prior to venom use. It is partly for this reason that most spider toxins encode a protective proregion that upon enzymatic cleavage is excised from the mature peptide. In order to identify the mature toxin sequence directly from toxin transcripts, without resorting to protein sequencing, the propeptide cleavage site in the toxin precursor must be predicted bioinformatically. We evaluated different machine learning strategies (support vector machines, hidden Markov model and decision tree) and developed an algorithm (SpiderP) for prediction of propeptide cleavage sites in spider toxins. Our strategy uses a support vector machine (SVM) framework that combines both local and global sequence information. Our method is superior or comparable to current tools for prediction of propeptide sequences in spider toxins. Evaluation of the SVM method on an independent test set of known toxin sequences yielded 96% sensitivity and 100% specificity. Furthermore, we sequenced five novel peptides (not used to train the final predictor) from the venom of the Australian tarantula Selenotypus plumipes to test the accuracy of the predictor and found 80% sensitivity and 99.6% 8-mer specificity. Finally, we used the predictor together with homology information to predict and characterize seven groups of novel toxins from the deeply sequenced venom gland transcriptome of S. plumipes, which revealed structural complexity and innovations in the evolution of the toxins. The precursor prediction tool (SpiderP) is freely available on ArachnoServer (http://www.arachnoserver.org/spiderP.html), a web portal to a comprehensive relational database of spider toxins. All training data, test data, and scripts used are available from the Spider

Neutralizing Monoclonal Antibodies against Disparate Epitopes on Ricin Toxin's Enzymatic Subunit Interfere with Intracellular Toxin Transport.

PubMed

Yermakova, Anastasiya; Klokk, Tove Irene; O'Hara, Joanne M; Cole, Richard; Sandvig, Kirsten; Mantis, Nicholas J

2016-03-07

Ricin is a member of the A-B family of bacterial and plant toxins that exploit retrograde trafficking to the Golgi apparatus and endoplasmic reticulum (ER) as a means to deliver their cytotoxic enzymatic subunits into the cytoplasm of mammalian cells. In this study we demonstrate that R70 and SyH7, two well-characterized monoclonal antibodies (mAbs) directed against distinct epitopes on the surface of ricin's enzymatic subunit (RTA), interfere with toxin transport from the plasma membrane to the trans Golgi network. Toxin-mAb complexes formed on the cell surface delayed ricin's egress from EEA-1(+) and Rab7(+) vesicles and enhanced toxin accumulation in LAMP-1(+) vesicles, suggesting the complexes were destined for degradation in lysosomes. Three other RTA-specific neutralizing mAbs against different epitopes were similar to R70 and SyH7 in terms of their effects on ricin retrograde transport. We conclude that interference with toxin retrograde transport may be a hallmark of toxin-neutralizing antibodies directed against disparate epitopes on RTA.

Towards Rational Design of a Toxoid Vaccine against the Heat-Stable Toxin of Escherichia coli

PubMed Central

Taxt, Arne M.; Diaz, Yuleima; Aasland, Rein; Clements, John D.; Nataro, James P.; Sommerfelt, Halvor

2016-01-01

Enterotoxigenic Escherichia coli (ETEC) is an important cause of diarrheal disease and death in children <5 years old. ETEC strains that express the heat-stable toxin (ST), with or without the heat-labile toxin, are among the four most important diarrhea-causing pathogens. This makes ST an attractive target for an ETEC vaccine. An ST vaccine should be nontoxic and elicit an immune response that neutralizes native ST without cross-reacting with the human endogenous guanylate cyclase C receptor ligands. To identify variants of ST with no or low toxicity, we screened a library of all 361 possible single-amino-acid mutant forms of ST by using the T84 cell assay. Moreover, we identified mutant variants with intact epitopes by screening for the ability to bind neutralizing anti-ST antibodies. ST mutant forms with no or low toxicity and intact epitopes are termed toxoid candidates, and the top 30 candidates all had mutations of residues A14, N12, and L9. The identification of nontoxic variants of L9 strongly suggests that it is a novel receptor-interacting residue, in addition to the previously identified N12, P13, and A14 residues. The screens also allowed us to map the epitopes of three neutralizing monoclonal antibodies, one of which cross-reacts with the human ligand uroguanylin. The common dominant epitope residue for all non-cross-reacting antibodies was Y19. Our results suggest that it should be possible to rationally design ST toxoids that elicit neutralizing immune responses against ST with minimal risk of immunological cross-reactivity. PMID:26883587

Protein degradation by ubiquitin–proteasome system in formation and labilization of contextual conditioning memory

PubMed Central

Sol Fustiñana, María; de la Fuente, Verónica; Federman, Noel; Freudenthal, Ramiro

2014-01-01

The ubiquitin–proteasome system (UPS) of protein degradation has been evaluated in different forms of neural plasticity and memory. The role of UPS in such processes is controversial. Several results support the idea that the activation of this system in memory consolidation is necessary to overcome negative constrains for plasticity. In this case, the inhibition of the UPS during consolidation impairs memory. Similar results were reported for memory reconsolidation. However, in other cases, the inhibition of UPS had no effect on memory consolidation and reconsolidation but impedes the amnesic action of protein synthesis inhibition after retrieval. The last finding suggests a specific action of the UPS inhibitor on memory labilization. However, another interpretation is possible in terms of the synthesis/degradation balance of positive and negative elements in neural plasticity, as was found in the case of long-term potentiation. To evaluate these alternative interpretations, other reconsolidation-interfering drugs than translation inhibitors should be tested. Here we analyzed initially the UPS inhibitor effect in contextual conditioning in crabs. We found that UPS inhibition during consolidation impaired long-term memory. In contrast, UPS inhibition did not affect memory reconsolidation after contextual retrieval but, in fact, impeded memory labilization, blocking the action of drugs that does not affect directly the protein synthesis. To extend these finding to vertebrates, we performed similar experiments in contextual fear memory in mice. We found that the UPS inhibitor in hippocampus affected memory consolidation and blocked memory labilization after retrieval. These findings exclude alternative interpretations to the requirement of UPS in memory labilization and give evidence of this mechanism in both vertebrates and invertebrates. PMID:25135196

Using the U.S. Geological Survey National Water Quality Laboratory LT-MDL to Evaluate and Analyze Data

USGS Publications Warehouse

Bonn, Bernadine A.

2008-01-01

A long-term method detection level (LT-MDL) and laboratory reporting level (LRL) are used by the U.S. Geological Survey?s National Water Quality Laboratory (NWQL) when reporting results from most chemical analyses of water samples. Changing to this method provided data users with additional information about their data and often resulted in more reported values in the low concentration range. Before this method was implemented, many of these values would have been censored. The use of the LT-MDL and LRL presents some challenges for the data user. Interpreting data in the low concentration range increases the need for adequate quality assurance because even small contamination or recovery problems can be relatively large compared to concentrations near the LT-MDL and LRL. In addition, the definition of the LT-MDL, as well as the inclusion of low values, can result in complex data sets with multiple censoring levels and reported values that are less than a censoring level. Improper interpretation or statistical manipulation of low-range results in these data sets can result in bias and incorrect conclusions. This document is designed to help data users use and interpret data reported with the LTMDL/ LRL method. The calculation and application of the LT-MDL and LRL are described. This document shows how to extract statistical information from the LT-MDL and LRL and how to use that information in USGS investigations, such as assessing the quality of field data, interpreting field data, and planning data collection for new projects. A set of 19 detailed examples are included in this document to help data users think about their data and properly interpret lowrange data without introducing bias. Although this document is not meant to be a comprehensive resource of statistical methods, several useful methods of analyzing censored data are demonstrated, including Regression on Order Statistics and Kaplan-Meier Estimation. These two statistical methods handle complex

HP LT Variscan metamorphism in the Cubito-Moura schists (Ossa-Morena Zone, southern Iberia)

NASA Astrophysics Data System (ADS)

Booth-Rea, Guillermo; Simancas, José Fernando; Azor, Antonio; Azañón, José Miguel; González-Lodeiro, Francisco; Fonseca, Paulo

2006-12-01

Multi-equilibrium thermobarometry shows that low-grade metapelites (Cubito-Moura schists) from the Ossa-Morena Zone underwent HP-LT metamorphism from 340-370 °C at 1.0-0.9 GPa to 400-450 °C at 0.8-0.7 GPa. These HP-LT equilibriums were reached by parageneses including white K mica, chlorite and chloritoid, which define the earliest schistosity (S 1) in these rocks. The main foliation in the schists is a crenulation cleavage (S 2), which developed during decompression from 0.8-0.7 to 0.4-0.3 GPa at increasing temperatures from 400-450 °C to 440-465 °C. Fe 3+ in chlorite decreased greatly during prograde metamorphism from molar fractions of 0.4 determined in syn-S 1 chlorites down to 0.1 in syn-S 2 chlorites. These new data add to previous findings of eclogites in the Moura schists indicating that a pile of allochtonous rocks situated next to the Beja-Acebuches oceanic amphibolites underwent HP-LT metamorphism during the Variscan orogeny. To cite this article: G. Booth-Rea et al., C. R. Geoscience 338 (2006).

A Double Blind Trial of Divalproex Sodium for Affective Lability and Alcohol Use Following Traumatic Brain Injury

DTIC Science & Technology

2010-10-01

comparable to lithium in treating acutely manic bipolar patients, and the FDA approved it in 1995 for this indication. Also, it is used in conjunction with...A Double Blind Trial of Divalproex Sodium for Affective Lability and Alcohol Use Following Traumatic Brain Injury PRINCIPAL INVESTIGATOR...Lability and Alcohol Use Following Traumatic Brain Injury 5b. GRANT NUMBER W81XWH-08-2-0652 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S

OBR-1-1/Fizika-LT(Letaushaya Tarelka/Flying Disk) experiment

NASA Image and Video Library

2009-04-24

ISS019-E-010230 (24 April 2009) --- Cosmonaut Gennady Padalka, Expedition 19/20 commander, is pictured near the OBR-1-1/?Fizika-LT? (Letaushaya Tarelka/Flying Disk) educational experiment, also called ?UFO?, floating freely in the Zvezda Service Module of the International Space Station. The OBR-1-1 is part of the OBRAZOVANIE (Education) suite of three educational demonstrations of physics in microgravity.

OBR-1-1/Fizika-LT(Letaushaya Tarelka/Flying Disk) experiment

NASA Image and Video Library

2009-04-24

ISS019-E-010081 (24 April 2009) --- Cosmonaut Gennady Padalka, Expedition 19/20 commander, is pictured near the OBR-1-1/?Fizika-LT? (Letaushaya Tarelka/Flying Disk) educational experiment, also called ?UFO?, floating freely in the Zvezda Service Module of the International Space Station. The OBR-1-1 is part of the OBRAZOVANIE (Education) suite of three educational demonstrations of physics in microgravity.

The novel acidophilic structure of the killer toxin from halotolerant yeast demonstrates remarkable folding similarity with a fungal killer toxin.

PubMed

Kashiwagi, T; Kunishima, N; Suzuki, C; Tsuchiya, F; Nikkuni, S; Arata, Y; Morikawa, K

1997-01-15

Several strains of yeasts and fungi produce proteinous substances, termed killer toxins, which kill sensitive strains. The SMK toxin, secreted by the halotolerant yeast Pichia farinosa KK1 strain, uniquely exhibits its maximum killer activity under conditions of acidic pH and high salt concentration. The toxin is composed of two distinct subunits, alpha and beta, which tightly interact with each other under acidic conditions. However, they are easily dissociated under neutral conditions and lose the killer activity. The three-dimensional structure of the SMK toxin will provide a better understanding of the mechanism of toxicity of this protein and the cause of its unique pH-dependent stability. Two crystal structures of the SMK toxin have been determined at 1.8 A resolution in different ionic strength conditions. The two subunits, alpha and beta, are jointly folded into an ellipsoidal, single domain structure belonging to the alpha/beta-sandwich family. The folding topology of the SMK toxin is essentially the same as that of the fungal killer toxin, KP4. This shared topology contains two left-handed split betaalphabeta motifs, which are rare in the other proteins. Many acidic residues are clustered at the bottom of the SMK toxin molecule. Some of the carboxyl sidechains interact with each other through hydrogen bonds. The ionic strength difference induces no evident structural change of the SMK toxin except that, in the high ionic strength crystal, a number of sulfate ions are electrostatically bound near the basic residues which are also locally distributed at the bottom of the toxin molecule. The two killer toxins, SMK and KP4, share a unique folding topology which contains a rare structural motif. This observation may suggest that these toxins are evolutionally and/or functionally related. The pH-dependent stability of the SMK toxin is a result of the intensive interactions between the carboxyl groups. This finding is important for protein engineering, for

Miscellaneous chemical toxins

USGS Publications Warehouse

Friend, M.

1999-01-01

The previous chapters provide information about some of the chemical toxins that have lethal effects on wild birds. The material presented in Section 7, Chemical Toxins, is far from comprehensive because wild birds are poisoned by a wide variety of toxic substances. Also, monitoring of wild bird mortality is not yet organized so that diagnostic findings can be extended to reflect the relative impacts among the types of toxins, within populations, or among species, geographic areas, and time. The data that are available are not collectively based on random sampling, nor do specimen collection and submission follow methodical assessment methods. Instead, most data simply document individual bird poisoning events. The inherent biases in this information include the species of birds observed dead (large birds in open areas are more likely to be observed dead than small forest birds); the species of birds likely to be submitted for analysis (bald eagles are more likely to be submitted than house sparrows); collection sites (agricultural fields are more likely to be observed than urban environments); geographic area of the country; season; reasons for submissions; and other variables. Nevertheless, findings from individual events reflect the causes of mortality associated with those events and collectively identify chemical toxins that repeatedly cause bird mortalities which result in carcass collection and sub

Liquiritin (LT) exhibits suppressive effects against the growth of human cervical cancer cells through activating Caspase-3 in vitro and xenograft mice in vivo.

PubMed

He, She-Hong; Liu, Hong-Gai; Zhou, Yu-Fei; Yue, Qing-Fen

2017-08-01

Cervical cancer is one of the most common female malignancies worldwide. Liquiritin (LT), a major constituent of Glycyrrhiza Radix, possesses a variety of pharmacological activities, including anti-cancer, anti-oxidative, anti-inflammatory and neuro-protective effects. However, its role in human cervical cancer remains to be elusive. In our study, we found that LT suppressed cervical cancer cell migration, invasion and cloning ability with little cytotoxicity to human normal cells. In addition, apoptosis was induced by LT in cervical cancer cells through activation of Caspase-3 and poly ADP-ribose polymerase (PARP) cleavage. LT-triggered apoptosis was dependent on extrinsic and intrinsic pathways, which were relied on Fas-associated protein with death domain (FADD)- and Bcl-2/Bax-regulated pathways, leading to Caspase-8 and Caspase-9 cleavage, respectively. LT was found to increase FADD expression, while reduce Bcl-2 expression, contributing to Caspase-3 cleavage. And tumor suppressors, p21 and p53, were enhanced after LT treatment, inhibiting the growth of cervical cancer cells in vitro. Significantly, in vivo study suggested that tumor growth was impeded by LT in a dose-dependent manner through enhancing apoptosis. Together, the data here revealed that LT was an effective and promising candidate for preventing human cervical cancer progression via apoptosis enhancement. Copyright © 2017. Published by Elsevier Masson SAS.

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 α-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.

An anaerobic incubation study of metal lability in drinking water treatment residue with implications for practical reuse.

PubMed

Wang, Changhui; Yuan, Nannan; Pei, Yuansheng

2014-06-15

Drinking water treatment residue (WTR) is an inevitable by-product generated during the treatment of drinking water with coagulating agents. The beneficial reuse of WTR as an amendment for environmental remediation has attracted growing interest. In this work, we investigated the lability of Al, As, Ba, Be, Ca, Cd, Co, Cr, Cu, Fe, Mg, Mn, Mo, Ni, Pb, Sr, V and Zn in Fe/Al hydroxide-comprised WTR based on a 180-day anaerobic incubation test using fractionation, in vitro digestion and a toxicity characteristic leaching procedure. The results indicated that most metals in the WTR were stable during anaerobic incubation and that the WTR before and after incubation could be considered non-hazardous in terms of leachable metal contents according to US EPA Method 1311. However, the lability of certain metals in the WTR after incubation increased substantially, especially Mn, which may be due to the reduction effect. Therefore, although there is no evidence presented to restrict the use of WTR in the field, the lability of metals (especially Mn) in WTR requires further assessment prior to field application. In addition, fractionation (e.g., BCR) is recommended for use to determine the potential lability of metals under various conditions. Copyright © 2014 Elsevier B.V. All rights reserved.

Sea Anemone (Cnidaria, Anthozoa, Actiniaria) Toxins: An Overview

PubMed Central

Frazão, Bárbara; Vasconcelos, Vitor; Antunes, Agostinho

2012-01-01

The Cnidaria phylum includes organisms that are among the most venomous animals. The Anthozoa class includes sea anemones, hard corals, soft corals and sea pens. The composition of cnidarian venoms is not known in detail, but they appear to contain a variety of compounds. Currently around 250 of those compounds have been identified (peptides, proteins, enzymes and proteinase inhibitors) and non-proteinaceous substances (purines, quaternary ammonium compounds, biogenic amines and betaines), but very few genes encoding toxins were described and only a few related protein three-dimensional structures are available. Toxins are used for prey acquisition, but also to deter potential predators (with neurotoxicity and cardiotoxicity effects) and even to fight territorial disputes. Cnidaria toxins have been identified on the nematocysts located on the tentacles, acrorhagi and acontia, and in the mucous coat that covers the animal body. Sea anemone toxins comprise mainly proteins and peptides that are cytolytic or neurotoxic with its potency varying with the structure and site of action and are efficient in targeting different animals, such as insects, crustaceans and vertebrates. Sea anemones toxins include voltage-gated Na+ and K+ channels toxins, acid-sensing ion channel toxins, Cytolysins, toxins with Kunitz-type protease inhibitors activity and toxins with Phospholipase A2 activity. In this review we assessed the phylogentic relationships of sea anemone toxins, characterized such toxins, the genes encoding them and the toxins three-dimensional structures, further providing a state-of-the-art description of the procedures involved in the isolation and purification of bioactive toxins. PMID:23015776

Sea anemone (Cnidaria, Anthozoa, Actiniaria) toxins: an overview.

PubMed

Frazão, Bárbara; Vasconcelos, Vitor; Antunes, Agostinho

2012-08-01

The Cnidaria phylum includes organisms that are among the most venomous animals. The Anthozoa class includes sea anemones, hard corals, soft corals and sea pens. The composition of cnidarian venoms is not known in detail, but they appear to contain a variety of compounds. Currently around 250 of those compounds have been identified (peptides, proteins, enzymes and proteinase inhibitors) and non-proteinaceous substances (purines, quaternary ammonium compounds, biogenic amines and betaines), but very few genes encoding toxins were described and only a few related protein three-dimensional structures are available. Toxins are used for prey acquisition, but also to deter potential predators (with neurotoxicity and cardiotoxicity effects) and even to fight territorial disputes. Cnidaria toxins have been identified on the nematocysts located on the tentacles, acrorhagi and acontia, and in the mucous coat that covers the animal body. Sea anemone toxins comprise mainly proteins and peptides that are cytolytic or neurotoxic with its potency varying with the structure and site of action and are efficient in targeting different animals, such as insects, crustaceans and vertebrates. Sea anemones toxins include voltage-gated Na⁺ and K⁺ channels toxins, acid-sensing ion channel toxins, Cytolysins, toxins with Kunitz-type protease inhibitors activity and toxins with Phospholipase A2 activity. In this review we assessed the phylogentic relationships of sea anemone toxins, characterized such toxins, the genes encoding them and the toxins three-dimensional structures, further providing a state-of-the-art description of the procedures involved in the isolation and purification of bioactive toxins.

Ricin detection: tracking active toxin.

PubMed

Bozza, William P; Tolleson, William H; Rivera Rosado, Leslie A; Zhang, Baolin

2015-01-01

Ricin is a plant toxin with high bioterrorism potential due to its natural abundance and potency in inducing cell death. Early detection of the active toxin is essential for developing appropriate countermeasures. Here we review concepts for designing ricin detection methods, including mechanism of action of the toxin, advantages and disadvantages of current detection assays, and perspectives on the future development of rapid and reliable methods for detecting ricin in environmental samples. Published by Elsevier Inc.

Twist-3 fragmentation effects for A LT in light hadron production from proton-proton collisions

DOE PAGES

Koike, Y.; Pitonyak, D.; Takagi, Y.; ...

2015-11-11

Here, we compute the contribution from the twist-3 fragmentation function for light hadron production in collisions between transversely and longitudinally polarized protons, i.e., View the MathML sourcep↑p →→hX, which can cause a double-spin asymmetry (DSA) A LT. This is a naïve T-even twist-3 observable that we analyze in collinear factorization using both Feynman gauge and lightcone gauge as well as give a general proof of color gauge invariance. So far only twist-3 effects in the transversely polarized proton have been studied for A LT in p↑p →→hX. However, there are indications that the naïve T-odd transverse single-spin asymmetry (SSA) Amore » N in p↑p→hX is dominated not by such distribution effects but rather by a fragmentation mechanism. Therefore, one may expect similarly that the fragmentation contribution is important for A LT. As a result, given possible plans at RHIC to measure this observable, it is timely to provide a calculation of this term.« less

The interactive effects of affect lability, negative urgency, and sensation seeking on young adult problematic drinking.

PubMed

Karyadi, Kenny; Coskunpinar, Ayca; Dir, Allyson L; Cyders, Melissa A

2013-01-01

Prior studies have suggested that affect lability might reduce the risk for problematic drinking among sensation seekers by compensating for their deficiencies in emotional reactivity and among individuals high on negative urgency by disrupting stable negative emotions. Due to the high prevalence of college drinking, this study examined whether affect lability interacted with sensation seeking and negative urgency to influence college student problematic drinking. 414 college drinkers (mean age: 20, 77% female, and 74% Caucasian) from a US Midwestern University completed self-administered questionnaires online. Consistent with our hypotheses, our results indicated that the effects of sensation seeking and negative urgency on problematic drinking weakened at higher levels of affect lability. These findings emphasize the importance of considering specific emotional contexts in understanding how negative urgency and sensation seeking create risk for problematic drinking among college students. These findings might also help us better understand how to reduce problematic drinking among sensation seekers and individuals high on negative urgency.

The Interactive Effects of Affect Lability, Negative Urgency, and Sensation Seeking on Young Adult Problematic Drinking

PubMed Central

Karyadi, Kenny; Coskunpinar, Ayca; Dir, Allyson L.; Cyders, Melissa A.

2013-01-01

Prior studies have suggested that affect lability might reduce the risk for problematic drinking among sensation seekers by compensating for their deficiencies in emotional reactivity and among individuals high on negative urgency by disrupting stable negative emotions. Due to the high prevalence of college drinking, this study examined whether affect lability interacted with sensation seeking and negative urgency to influence college student problematic drinking. 414 college drinkers (mean age: 20, 77% female, and 74% Caucasian) from a US Midwestern University completed self-administered questionnaires online. Consistent with our hypotheses, our results indicated that the effects of sensation seeking and negative urgency on problematic drinking weakened at higher levels of affect lability. These findings emphasize the importance of considering specific emotional contexts in understanding how negative urgency and sensation seeking create risk for problematic drinking among college students. These findings might also help us better understand how to reduce problematic drinking among sensation seekers and individuals high on negative urgency. PMID:24826366

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

2012-12-04

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.

Marine and freshwater toxins.

PubMed

Hungerford, James M

2006-01-01

In a very busy and exciting year, 2005 included First Action approval of a much needed official method for paralytic shellfish toxins and multiple international toxin symposia highlighted by groundbreaking research. These are the first-year milestones and activities of the Marine and Freshwater Toxins Task Force and Analytical Community. Inaugurated in 2004 and described in detail in last year's General Referee Report (1) this international toxins group has grown to 150 members from many regions and countries. Perhaps most important they are now making important and global contributions to food safety and to providing alternatives to animal-based assays. Official Method 2005.06 was first approved in late 2004 by the Task Force and subsequently Official First Action in 2005 (2) by the Methods Committee on Natural Toxins and Food Allergens and the Official Methods Board. This nonproprietary method (3) is a precolumn oxidation, liquid chromatographic method that makes good use of fluorescence detection to provide high sensitivity detection of the saxitoxins. It has also proven to be rugged enough for regulatory use and the highest level of validation. As pointed out in the report of method principle investigator and Study Director James Lawrence, approval of 2005.06 now provides the first official alternative to the mouse bioassay after many decades of shellfish monitoring. This past year in April 2005 the group also held their first international conference, "Marine and Freshwater Toxins Analysis: Ist Joint Symposium and AOAC Task Force Meeting," in Baiona, Spain. The 4-day conference consisted of research and stakeholder presentations and symposium-integrated subgroup sessions on ciguatoxins, saxitoxin assays and liquid chromatography (LC) methods for saxitoxins and domoic acids, okadaiates and azaspiracids, and yessotoxins. Many of these subgroups were recently formed in 2005 and are working towards their goals of producing officially validated analytical methods

Role of Botulinum Toxin in Depression.

PubMed

Parsaik, Ajay K; Mascarenhas, Sonia S; Hashmi, Aqeel; Prokop, Larry J; John, Vineeth; Okusaga, Olaoluwa; Singh, Balwinder

2016-03-01

The goal of this review was to consolidate the evidence concerning the efficacy of botulinum toxin type A (onabotulinumtoxinA) in depression. We searched MEDLINE, EMBASE, Cochrane, and Scopus through May 5, 2014, for studies evaluating the efficacy of botulinum toxin A in depression. Only randomized controlled trials were included in the meta-analysis. A pooled mean difference in primary depression score, and pooled odds ratio for response and remission rate with 95% confidence interval (CI) were estimated using the random-effects model. Heterogeneity was assessed using Cochran Q test and χ statistic. Of the 639 articles that were initially retrieved, 5 studies enrolling 194 subjects (age 49±9.6 y) were included in the systematic review, and 3 randomized controlled trials enrolling 134 subjects were included in the meta-analysis. The meta-analysis showed a significant decrease in mean primary depression scores among patients who received botulinum toxin A compared with placebo (-9.80; 95% CI, -12.90 to -6.69) with modest heterogeneity between the studies (Cochran Q test, χ=70). Response and remission rates were 8.3 and 4.6 times higher, respectively, among patients receiving botulinum toxin A compared with placebo, with no heterogeneity between the studies. The 2 studies excluded from the meta-analysis also found a significant decrease in primary depression scores in patients after receiving botulinum toxin A. A few subjects had minor side effects, which were similar between the groups receiving botulinum toxin and those receiving placebo. This study suggests that botulinum toxin A can produce significant improvement in depressive symptoms and is a safe adjunctive treatment for patients receiving pharmacotherapy for depression. Future trials are needed to evaluate the antidepressant effect per se of botulinum toxin A and to further elucidate the underlying antidepressant mechanism of botulinum toxin A.

Emerging insights into the biology of typhoid toxin

PubMed Central

Fowler, Casey C.; Chang, Shu-Jung; Gao, Xiang; Geiger, Tobias; Stack, Gabrielle; Galán, Jorge E.

2017-01-01

Typhoid toxin is a unique A2B5 exotoxin and an important virulence factor for Salmonella Typhi, the cause of typhoid fever. In the decade since its initial discovery, great strides have been made in deciphering the unusual biological program of this toxin, which is fundamentally different from related toxins in many ways. Purified typhoid toxin administered to laboratory animals causes many of the symptoms of typhoid fever, suggesting that typhoid toxin is a central factor in this disease. Further advances in understanding the biology of this toxin will help guide the development of badly needed diagnostics and therapeutic interventions that target this toxin to detect, prevent or treat typhoid fever. PMID:28213043

Immunogenicity of nuclear-encoded LTB:ST fusion protein from Escherichia coli expressed in tobacco plants.

PubMed

Rosales-Mendoza, Sergio; Soria-Guerra, Ruth E; Moreno-Fierros, Leticia; Govea-Alonso, Dania O; Herrera-Díaz, Areli; Korban, Schuyler S; Alpuche-Solís, Ángel G

2011-06-01

Enterotoxigenic Escherichia coli (ETEC) is one of the main causative agents of diarrhea in infants and for travelers. Inclusion of a heat-stable (ST) toxin into vaccine formulations is mandatory as most ETEC strains can produce both heat-labile (LT) and ST enterotoxins. In this study, a genetic fusion gene encoding for an LTB:ST protein has been constructed and transferred into tobacco via Agrobacterium tumefaciens-mediated transformation. Transgenic tobacco plants carrying the LTB:ST gene are then subjected to GM1-ELISA revealing that the LTB:ST has assembled into pentamers and displays antigenic determinants from both LTB and ST. Protein accumulation of up to 0.05% total soluble protein is detected. Subsequently, mucosal and systemic humoral responses are elicited in mice orally dosed with transgenic tobacco leaves. This has suggested that the plant-derived LTB:ST is immunogenic via the oral route. These findings are critical for the development of a plant-based vaccine capable of eliciting broader protection against ETEC and targeting both LTB and ST. Features of this platform in comparison to transplastomic approaches are discussed.

Plant-based immunocontraceptive control of wildlife--"potentials, limitations, and possums".

PubMed

Polkinghorne, Ian; Hamerli, Denes; Cowan, Phil; Duckworth, Janine

2005-03-07

Possums (Trichosurus vulpecula), originally introduced from Australia, are spread over 90% of New Zealand and cause major economic and environmental damage. Immunocontraception has been suggested as a humane means to control them. Marsupial-specific reproductive antigens expressed at high levels in edible transgenic plant tissue might provide a safe, effective, and cheap oral delivery bait for immunocontraceptive control. As proof of concept, female possums vaccinated with immunocontraceptive antigens showed reduced fertility, and possums fed with potato-expressed heat labile toxin-B (LT-B) had mucosal and systemic immune responses to the antigen. This demonstrated that immunocontraception was effective in possums and that oral delivery in edible plant material might be possible. Nuclear transformation with reporter genes showed that transgenic carrot roots accumulate high levels of foreign protein in edible tissues, indicating their potential as a delivery vector. However, prior to attempts at large scale production, more effective immunocontraceptive antigen-adjuvant formulations are probably required before plant-based immunocontraception can become a major tool for immunocontraceptive control of overabundant vertebrate pests.

Determining the activity of mucosal adjuvants.

PubMed

Baudner, Barbara C; Giudice, Giuseppe Del

2010-01-01

Mucosal vaccination offers the advantage of blocking pathogens at the portal of entry, improving patient's compliance, facilitating vaccine delivery, and decreasing the risk of unwanted spread of infectious agents via contaminated syringes.Recent advances in vaccinology have created an array of vaccine constructs that can be delivered to mucosal surfaces of the respiratory, gastrointestinal, and genitourinary tracts using intranasal, oral, and vaginal routes. Due to the different characteristics of mucosal immune response, as compared with systemic response, mucosal immunization requires particular methods of antigen presentation. Well-tolerated adjuvants that enhance the efficacy of such vaccines will play an important role in mucosal immunization. Among promising mucosal adjuvants, mutants of cholera toxin and the closely related heat-labile enterotoxin (LT) of enterotoxigenic Escherichia coli present powerful tools, augmenting the local and systemic serum antibody response to co-administered antigens.In this chapter, we describe the formulation and application of vaccines using the genetically modified LTK63 mutant as a prototype of the family of these mucosal adjuvants and the tools to determine its activity in the mouse model.

Botulinum toxin therapy for limb dystonias.

PubMed

Yoshimura, D M; Aminoff, M J; Olney, R K

1992-03-01

We investigated the effectiveness of botulinum toxin in 17 patients with limb dystonias (10 with occupational cramps, three with idiopathic dystonia unrelated to activity, and two each with post-stroke and parkinsonian dystonia) in a placebo-controlled, blinded study. We identified affected muscles clinically and by recording the EMG from implanted wire electrodes at rest and during performance of tasks that precipitated abnormal postures. There were three injections given with graded doses of toxin (average doses, 5 to 10, 10 to 20, and 20 to 40 units per muscle) and one with placebo, in random order. Subjective improvement occurred after 53% of injections of botulinum toxin, and this was substantial in 24%. Only one patient (7%) improved after placebo injection. Subjective improvement occurred in 82% of patients with at least one dose of toxin, lasting for 1 to 4 months. Response rates were similar between clinical groups. Objective evaluation failed to demonstrate significant improvement following treatment with toxin compared with placebo. The major side effect was transient focal weakness after 53% of injections of toxin.

Anthrax toxin.

PubMed

Bhatnagar, R; Batra, S

2001-01-01

Anthrax is primarily a disease of herbivores caused by gram-positive, aerobic, spore-forming Bacillus anthracis. Humans are accidental hosts through the food of animal origin and animal products. Anthrax is prevelant in most parts of the globe, and cases of anthrax have been reported from almost every country. Three forms of the disease have been recognized: cutaneous (through skin), gastrointestinal (through alimentary tract), and pulmonary (by inhalation of spores). The major virulence factors of Bacillus anthracis are a poly-D glutamic acid capsule and a three-component protein exotoxin. The genes coding for the toxin and the enzymes responsible for capsule production are carried on plasmid pXO1 and pXO2, respectively. The three proteins of the exotoxin are protective antigen (PA, 83 kDa), lethal factor (LF, 90 kDa), and edema factor (EF, 89 kDa). The toxins follow the A-B model with PA being the B moeity and LF/EF, the alternative A moeities. LF and EF are individually nontoxic, but in combination with PA form two toxins causing different pathogenic responses in animals and cultured cells. PA + LF forms the lethal toxin and PA + EF forms the edema toxin. During the process of intoxication, PA binds to the cell surface receptor and is cleaved at the sequence RKKR (167) by cell surface proteases such as furin generating a cell-bound, C-terminal 63 kDa protein (PA63). PA63 possesses a binding site to which LF or EF bind with high affinity. The complex is then internalized by receptor-mediated endocytosis. Acidification of the vesicle leads to instertion of PA63 into the endosomal membrane and translocation of LF/EF across the bilayer into the cytosol where they exert their toxic effects. EF has a calcium- and calmodulin-dependent adenylate cyclase activity. Recent reports indicate that LF is a protease that cleaves the amino terminus of mitogen-activated protein kinase kinases 1 and 2 (MAPKK1 and 2), and this cleavage inactivates MAPKK1 and thus inhibits the

Protection of Pyruvate,Pi Dikinase from Maize against Cold Lability by Compatible Solutes 1

PubMed Central

Krall, John P.; Edwards, Gerald E.; Andreo, Carlos S.

1989-01-01

Most C4 species are chilling sensitive and certain enzymes like pyruvate,Pi dikinase of the C4 pathway are also cold labile. The ability of cations and compatible solutes to protect maize (Zea mays) dikinase against cold lability was examined. The enzyme in desalted extracts at pH 8 from preilluminated leaves could be protected against cold lability (at 0°C) by the divalent cations Mn2+, Mg2+, and Ca2+. There was substantial protection by sulfate based salts but little protection by chloride based salts of potassium or ammonium (concentration 250 millimolar). The degree of protection against cold lability under limiting MgCl2 (5 millimolar) was pH sensitive (maximum protection at pH 8), but independent of ionic strength (up to 250 millimolar by addition of KCl). In catalysis Mg2+ is required and Mn2+ could not substitute as a cofactor. Several compatible solutes reduced or prevented the cold inactivation of dikinase (in desalted extracts and the partially purified enzyme), including glycerol, proline, glycinebetaine and trimethylamine-N-oxide (TMAO). TMAO and Mg2+ had an additive effect in protecting dikinase against cold inactivation. TMAO could largely substitute for the divalent cation and addition of TMAO during cold treatment prevented further inactivation. Cold inactivation was partially reversed by incubation at room temperature; with addition of TMAO reversal was complete. The temperature dependence of inactivation at pH 8 and 3 millimolar MgCl2 was evaluated by incubation at 2 to 17°C for 45 minutes, followed by assay at room temperature. At preincubation temperatures below 11°C there was a progressive inactivation which could be prevented by TMAO (450 millimolar). The results are discussed relative to possible effects of the solutes on the quaternary structure of this enzyme, which is known to dissociate at low temperatures. PMID:16666527

Marine Neurotoxins: Ingestible Toxins.

PubMed

Stommel, Elijah W.; Watters, Michael R.

2004-03-01

Fish and shellfish account for a significant portion of food-borne illnesses throughout the world. In general, three classes of diseases result from seafood consumption--intoxication, allergies, and infections. In this review, the authors discuss several seafood-borne toxins, including domoic acid, which acts on the central nervous system. In addition, the authors discuss ciguatoxin-, brevetoxin-, saxitoxin-, tetrodotoxin-, and scombroid-related histamine toxicity, all of which act primarily on the peripheral nervous system. Fish has become a very popular food in the US mostly related to its potential health benefits. Fish is consumed to such a degree that fishing stocks are reportedly at an all time low from what seemed like an endless supply even 30 years ago. One of the most significant threats to human intoxication is the recreational harvest of shellfish, often times located in remote locations where the harvesters are subsistent on fishery resources and have no monitoring in place. The hazard to intoxication is not as common in purchased seafood, which is more stringently regulated, yet still is a serious problem. Most ingestible toxins are thermo-stable and therefore unaffected by cooking, freezing, or salting. Air transport of consumable products throughout the world makes it easy to obtain exotic edibles from far away countries. A seemingly unusual toxin can be more commonly encountered than previously thought and it is important to consider this when evaluating patients. Recognition and treatment of various neurologic symptoms related to seafood ingestion is paramount in today's mobile, gastronomic world. Specific treatments vary with each individual toxin and with the individual's specific reaction to the toxin. Generally, some degree of medical care is required with all ingestible toxin exposure, ranging from simple administration of medication and hydration to ventilatory and cardiovascular support.

Novel bacterial ADP-ribosylating toxins: structure and function

PubMed Central

Simon, Nathan C.; Aktories, Klaus; Barbieri, Joseph T.

2018-01-01

Preface Bacterial ADP-ribosyltransferase toxins (bARTTs) transfer ADP-ribose to eukaryotic proteins to promote bacterial pathogenesis. In this review we use prototype bARTTs, such as diphtheria and pertussis toxins, as references for the characterization of several new bARTTs from human, insect, and plant pathogens, which were identified recently through bioinformatic analyses. Several of these toxins, including Cholix toxin from Vibrio cholerae, SpyA from Streptococcus pyogenes, HopU1 from Pseudomonas syringae, and the Tcc toxins from Photorhabdus luminescens, ADP-ribosylate novel substrates and possess unique organizations, which distinguish them from the reference toxins. The characterization of these toxins extends our appreciation for the variety of structure-function properties possessed by bARTTs and their roles in bacterial pathogenesis. PMID:25023120

Military Importance of Natural Toxins and Their Analogs.

PubMed

Pitschmann, Vladimír; Hon, Zdeněk

2016-04-28

Toxin weapon research, development, production and the ban on its uses is an integral part of international law, with particular attention paid to the protection against these weapons. In spite of this, hazards associated with toxins cannot be completely excluded. Some of these hazards are also pointed out in the present review. The article deals with the characteristics and properties of natural toxins and synthetic analogs potentially constituting the basis of toxin weapons. It briefly describes the history of military research and the use of toxins from distant history up to the present age. With respect to effective disarmament conventions, it mentions certain contemporary concepts of possible toxin applications for military purposes and the protection of public order (suppression of riots); it also briefly refers to the question of terrorism. In addition, it deals with certain traditional as well as modern technologies of the research, synthesis, and use of toxins, which can affect the continuing development of toxin weapons. These are, for example, cases of new toxins from natural sources, their chemical synthesis, production of synthetic analogs, the possibility of using methods of genetic engineering and modern biotechnologies or the possible applications of nanotechnology and certain pharmaceutical methods for the effective transfer of toxins into the organism. The authors evaluate the military importance of toxins based on their comparison with traditional chemical warfare agents. They appeal to the ethics of the scientific work as a principal condition for the prevention of toxin abuse in wars, military conflicts, as well as in non-military attacks.

Characteristics of labile organic carbon fractions in reclaimed mine soils: Evidence from three reclaimed forests in the Pingshuo opencast coal mine, China.

PubMed

Yuan, Ye; Zhao, Zhongqiu; Li, Xuezhen; Wang, Yangyang; Bai, Zhongke

2018-02-01

The reclamation of discarded spoils has the potential to stimulate carbon (C) sequestration in reclaimed mine soils (RMSs). Nevertheless, to date the temporal dynamics of labile organic C fractions have not been sufficiently elucidated in RMSs. In this study, soil organic carbon (SOC) and labile organic C fractions, including microbial biomass organic C (MBC), easily oxidizable organic C (EOC) and dissolved organic C (DOC), were determined in Robinia pseudoacacia monoculture forests (reclamation periods of 0, 8, 10, 13, 15, 18 and 30years), Pinus tabuliformis forests (reclamation periods of 0, 10, 19, 23 and 25years) and Ulmus pumila forests (reclamation periods of 0, 18, 20 and 22years) situated on RMSs in the Pingshuo opencast coal mine, China. Changes in labile organic C fractions within the soil profiles (0-100cm) were also identified at the 18- or 19-year plots under the three monoculture forests. Our results showed that, SOC and labile organic C fractions, together with soil microbial quotient (SMQ) and C management index (CMI), increased with time since reclamation, indicating that the quality of RMSs improved over time after initial reclamation under the three forest types. R. pseudoacacia significantly increased the accretion of SOC and EOC in the early stage of reclamation while P. tabuliformis accelerated the accumulation of the MBC fraction. Results for U. pumila indicated that this species had a better ability to store C in RMSs 10years or more after reclamation. SOC and labile organic C fractions both had S-shaped distributions within the soil profiles (0-100cm), with the 0-20cm layer recording the highest values (P<0.05). Labile organic C fractions were closely associated and correlated with soil physicochemical properties; our results also showed that nitrogen played an important role in the development of labile organic C fractions. Overall, reclamation accelerated the accretion of both SOC and labile organic C fractions, results of which varied

Definitive airway management of patients presenting with a pre-hospital inserted King LT(S)-D laryngeal tube airway: a historical cohort study.

PubMed

Subramanian, Arun; Garcia-Marcinkiewicz, Annery G; Brown, Daniel R; Brown, Michael J; Diedrich, Daniel A

2016-03-01

The King LT(S)-D laryngeal tube (King LT) has gained popularity as a bridge airway for pre-hospital airway management. In this study, we retrospectively reviewed the use of the King LT and its associated airway outcomes at a single Level 1 trauma centre. The data on all adult patients presenting to the Mayo Clinic in Rochester, Minnesota with a King LT in situ from July 1, 2007 to October 10, 2012 were retrospectively evaluated. Data collected and descriptively analyzed included patient demographics, comorbidities, etiology of respiratory failure, airway complications, subsequent definitive airway management technique, duration of mechanical ventilation, and status at discharge. Forty-eight adult patients met inclusion criteria. The most common etiology for respiratory failure requiring an artificial airway was cardiac arrest [28 (58%) patients] or trauma [9 (19%) patients]. Four of the nine trauma patients had facial trauma. Surgical tracheostomy was the definitive airway management technique in 14 (29%) patients. An airway exchange catheter, direct laryngoscopy, and video laryngoscopy were used in 11 (23%), ten (21%), and ten (21%) cases, respectively. Seven (78%) of the trauma patients underwent surgical tracheostomy compared with seven (18%) of the medical patients. Adverse events associated with King LT use occurred in 13 (27%) patients, with upper airway edema (i.e., tongue engorgement and glottic edema) being most common (19%). In this study of patients presenting to a hospital with a King LT, the majority of airway exchanges required an advanced airway management technique beyond direct laryngoscopy. Upper airway edema was the most common adverse observation associated with King LT use.

Association between the clinical classification of hypothyroidism and reduced TSH in LT4 supplemental replacement treatment for pregnancy in China.

PubMed

Zhang, Lyu; Zhang, Zhaoyun; Ye, Hongying; Zhu, Xiaoming; Li, Yiming

2016-01-01

The study was aimed to evaluate the effects of levothyroxine (LT4) supplemental replacement treatment for pregnancy and analyze the associations between the clinical classification of hypothyroidism and reduced thyroid-stimulating hormone (TSH) in LT4 therapy. Totally, 195 pregnant women with hypothyroidism receiving routine prenatal care were enrolled. They were categorized into three groups: overt hypothyroidism (OH), subclinical hypothyroidism (SCH) with negative thyroperoxidase antibody (TPOAb), and SCH with positive TPOAb. The association between the clinical classification and reduced TSH in LT4 supplemental replacement treatment was assessed. The results indicated that reduced TSH was significantly different among the groups according to the clinical classifications (p = 0.043). The result was also significantly different between patients with OH and patients with SCH and negative TPOAb (p = 0.036). Similar result was reported for the comparison between patients with OH and patients with SCH and positive TPOAb (p = 0.016). Multiple variable analyses showed that LT4 supplementation, gestational age and the variable of clinical classifications were associated with reduced TSH independently. Our data suggested that the therapeutic effect of substitutive treatment with LT4 was significantly associated with different clinical classifications of hypothyroidism in pregnancy and the treatment should begin as soon as possible after diagnosis.

A New Type of Toxin A-Negative, Toxin B-Positive Clostridium difficile Strain Lacking a Complete tcdA Gene

PubMed Central

Marín, Mercedes; Martín, Adoración; Rupnik, Maja

2014-01-01

Toxins A and B are the main virulence factors of Clostridium difficile and are the targets for molecular diagnostic tests. Here, we describe a new toxin A-negative, toxin B-positive, binary toxin CDT (Clostridium difficile transferase)-negative (A− B+ CDT−) toxinotype (XXXII) characterized by a variant type of pathogenicity locus (PaLoc) without tcdA and with atypical organization of the PaLoc integration site. PMID:25428159

Infectious Multiple Drug Resistance in the Enterobacteriaceae

DTIC Science & Technology

1983-10-01

producing a form of ST that does not Vibrio cholera and Eichernchia co/i. Infect Immun undergo the same posttranslational modification 1974; 10:320-7... cholera toxin. Although there have been numerous reports of the relationship between E. coli LT toxin (and cholera toxin) and a putative enterotoxin...dissect the fine molecular structure of cholera toxin and thereby create a general strategy by which subunit vaccines might be directly synthesized in the

Toxins of filamentous fungi.

PubMed

Bhatnagar, Deepak; Yu, Jiujiang; Ehrlich, Kenneth C

2002-01-01

Mycotoxins are low-molecular-weight secondary metabolites of fungi. The most significant mycotoxins are contaminants of agricultural commodities, foods and feeds. Fungi that produce these toxins do so both prior to harvest and during storage. Although contamination of commodities by toxigenic fungi occurs frequently in areas with a hot and humid climate (i.e. conditions favorable for fungal growth), they can also be found in temperate conditions. Production of mycotoxins is dependent upon the type of producing fungus and environmental conditions such as the substrate, water activity (moisture and relative humidity), duration of exposure to stress conditions and microbial, insect or other animal interactions. Although outbreaks of mycotoxicoses in humans have been documented, several of these have not been well characterized, neither has a direct correlation between the mycotoxin and resulting toxic effect been well established in vivo. Even though the specific modes of action of most of the toxins are not well established, acute and chronic effects in prokaryotic and eukaryotic systems, including humans have been reported. The toxicity of the mycotoxins varies considerably with the toxin, the animal species exposed to it, and the extent of exposure, age and nutritional status. Most of the toxic effects of mycotoxins are limited to specific organs, but several mycotoxins affect many organs. Induction of cancer by some mycotoxins is a major concern as a chronic effect of these toxins. It is nearly impossible to eliminate mycotoxins from the foods and feed in spite of the regulatory efforts at the national and international levels to remove the contaminated commodities. This is because mycotoxins are highly stable compounds, the producing fungi are ubiquitous, and food contamination can occur both before and after harvest. Nevertheless, good farm management practices and adequate storage facilities minimize the toxin contamination problems. Current research is

Mechanism-based design of labile precursors for chromium(I) chemistry

DOE PAGES

Akturk, Eser S.; Yap, Glenn P. A.; Theopold, Klaus H.

2015-08-27

Here, we report that dinitrogen complexes of the type Tp R,RCr–N 2–CrTp R,R are not the most labile precursors for Cr(I) chemistry, as they are sterically protected from obligatory associative ligand substitution. A mononuclear alkyne complex – Tp tBu,MeCr(η 2-C 2(SiMe 3) 2) – proved to be much more reactive.

Molecular insights into the microbial formation of marine dissolved organic matter: recalcitrant or labile?

NASA Astrophysics Data System (ADS)

Koch, B. P.; Kattner, G.; Witt, M.; Passow, U.

2014-08-01

The degradation of marine dissolved organic matter (DOM) is an important control variable in the global carbon cycle. For our understanding of the kinetics of organic matter cycling in the ocean, it is crucial to achieve a mechanistic and molecular understanding of its transformation processes. A long-term microbial experiment was performed to follow the production of non-labile DOM by marine bacteria. Two different glucose concentrations and dissolved algal exudates were used as substrates. We monitored the bacterial abundance, concentrations of dissolved and particulate organic carbon (DOC, POC), nutrients, amino acids and transparent exopolymer particles (TEP) for 2 years. The molecular characterization of extracted DOM was performed by ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) after 70 days and after ∼2 years of incubation. Although glucose quickly degraded, a non-labile DOC background (5-9% of the initial DOC) was generated in the glucose incubations. Only 20% of the organic carbon from the algal exudate degraded within the 2 years of incubation. The degradation rates for the non-labile DOC background in the different treatments varied between 1 and 11 μmol DOC L-1 year-1. Transparent exopolymer particles, which are released by microorganisms, were produced during glucose degradation but decreased back to half of the maximum concentration within less than 3 weeks (degradation rate: 25 μg xanthan gum equivalents L-1 d-1) and were below detection in all treatments after 2 years. Additional glucose was added after 2 years to test whether labile substrate can promote the degradation of background DOC (co-metabolism; priming effect). A priming effect was not observed but the glucose addition led to a slight increase of background DOC. The molecular analysis demonstrated that DOM generated during glucose degradation differed appreciably from DOM transformed during the degradation of the algal exudates. Our

Microbial control of soil organic matter mineralization responses to labile carbon in subarctic climate change treatments.

PubMed

Rousk, Kathrin; Michelsen, Anders; Rousk, Johannes

2016-12-01

Half the global soil carbon (C) is held in high-latitude systems. Climate change will expose these to warming and a shift towards plant communities with more labile C input. Labile C can also increase the rate of loss of native soil organic matter (SOM); a phenomenon termed 'priming'. We investigated how warming (+1.1 °C over ambient using open top chambers) and litter addition (90 g m -2  yr -1 ) treatments in the subarctic influenced the susceptibility of SOM mineralization to priming, and its microbial underpinnings. Labile C appeared to inhibit the mineralization of C from SOM by up to 60% within hours. In contrast, the mineralization of N from SOM was stimulated by up to 300%. These responses occurred rapidly and were unrelated to microbial successional dynamics, suggesting catabolic responses. Considered separately, the labile C inhibited C mineralization is compatible with previously reported findings termed 'preferential substrate utilization' or 'negative apparent priming', while the stimulated N mineralization responses echo recent reports of 'real priming' of SOM mineralization. However, C and N mineralization responses derived from the same SOM source must be interpreted together: This suggested that the microbial SOM-use decreased in magnitude and shifted to components richer in N. This finding highlights that only considering SOM in terms of C may be simplistic, and will not capture all changes in SOM decomposition. The selective mining for N increased in climate change treatments with higher fungal dominance. In conclusion, labile C appeared to trigger catabolic responses of the resident microbial community that shifted the SOM mining to N-rich components; an effect that increased with higher fungal dominance. Extrapolating from these findings, the predicted shrub expansion in the subarctic could result in an altered microbial use of SOM, selectively mining it for N-rich components, and leading to a reduced total SOM-use. © 2016 John Wiley

Differential Requirement for the Translocation of Clostridial Binary Toxins: Iota Toxin Requires a Membrane Potential Gradient

DTIC Science & Technology

2007-02-28

be inter- changed to form biologically-active, hybrid toxins. Thereby, Ib can internalize the enzymatic components from either C. spiroforme or C...since chloro- quine, monensin, nigericin, or ammonium chloride did not in- hibit its activity (Fig. 2A). C. spiroforme toxin, which is very highly...ER [50]. These results are in agreement with a recent report [15], and an earlier finding [45] that there was no effect of C. spiroforme toxin when

Toxin Detection by Surface Plasmon Resonance

PubMed Central

Hodnik, Vesna; Anderluh, Gregor

2009-01-01

Significant efforts have been invested in the past years for the development of analytical methods for fast toxin detection in food and water. Immunochemical methods like ELISA, spectroscopy and chromatography are the most used in toxin detection. Different methods have been linked, e.g. liquid chromatography and mass spectrometry (LC-MS), in order to detect as low concentrations as possible. Surface plasmon resonance (SPR) is one of the new biophysical methods which enables rapid toxin detection. Moreover, this method was already included in portable sensors for on-site determinations. In this paper we describe some of the most common methods for toxin detection, with an emphasis on SPR. PMID:22573957

Identification of the cellular receptor of Clostridium spiroforme toxin.

PubMed

Papatheodorou, Panagiotis; Wilczek, Claudia; Nölke, Thilo; Guttenberg, Gregor; Hornuss, Daniel; Schwan, Carsten; Aktories, Klaus

2012-04-01

Clostridium spiroforme produces the binary actin-ADP-ribosylating toxin CST (C. spiroforme toxin), which has been proposed to be responsible for diarrhea, enterocolitis, and eventually death, especially in rabbits. Here we report on the recombinant production of the enzyme component (CSTa) and the binding component (CSTb) of C. spiroforme toxin in Bacillus megaterium. By using the recombinant toxin components, we show that CST enters target cells via the lipolysis-stimulated lipoprotein receptor (LSR), which has been recently identified as the host cell receptor of the binary toxins Clostridium difficile transferase (CDT) and Clostridium perfringens iota toxin. Microscopic studies revealed that CST, but not the related Clostridium botulinum C2 toxin, colocalized with LSR during toxin uptake and traffic to endosomal compartments. Our findings indicate that CST shares LSR with C. difficile CDT and C. perfringens iota toxin as a host cell surface receptor.

Trauma exposure and heavy drinking and drug use among college students: Identifying the roles of negative and positive affect lability in a daily diary study.

PubMed

Weiss, Nicole H; Bold, Krysten W; Contractor, Ateka A; Sullivan, Tami P; Armeli, Stephen; Tennen, Howard

2018-04-01

Trauma exposure is linked to heavy drinking and drug use among college students. Extant research reveals positive associations between negative affect lability and both trauma exposure and alcohol use. This study aimed to extend past research by using daily diary methods to test whether (a) individuals with (versus without) trauma exposure experience greater negative and positive affect lability, (b) negative and positive affect lability are associated with heavy drinking and drug use, and (c) negative and positive affect lability mediate the relations between trauma exposure and heavy drinking and drug use. Participants were 1640 college students (M age=19.2, 54% female, 80% European American) who provided daily diary data for 30days via online surveys. Daily diaries assessed negative and positive affect and substance use (i.e., percent days of heavy drinking, percent days of drug use, total number of drugs used). Individuals with (versus without) a history of trauma exposure demonstrated higher levels of negative and positive affect lability. Negative, but not positive, affect lability was associated with percent days of heavy drinking, percent days of drug use, and total number of drugs used, and mediated the associations between trauma exposure and heavy drinking and drug use outcomes. Findings provide support for the underlying role of negative affect lability in the relations between trauma exposure and heavy drinking and drug use among college students, suggesting that treatments targeting negative affect lability may potentially serve to reduce heavy drinking and drug use among trauma-exposed college students. Copyright © 2017 Elsevier Ltd. All rights reserved.

DETERMINATION OF APPARENT QUANTUM YIELD SPECTRA FOR THE FORMATION OF BIOLOGICALLY LABILE PHOTOPRODUCTS

EPA Science Inventory

Quantum yield spectra for the photochemical formation of biologically labile photoproducts from dissolved organic matter (DOM) have not been available previously, although they would greatly facilitate attempts to model photoproduct formation rates across latitudinal, seasonal, a...

Molecular imaging of labile iron(II) pools in living cells with a turn-on fluorescent probe.

PubMed

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

2013-10-09

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 Fe(2+) pools in aqueous solution and 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 Fe(2+) over a range of cellular metal ions in their bioavailable forms. We show that this first-generation chemical tool for fluorescence Fe(2+) 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.

Identification of the Cellular Receptor of Clostridium spiroforme Toxin

PubMed Central

Papatheodorou, Panagiotis; Wilczek, Claudia; Nölke, Thilo; Guttenberg, Gregor; Hornuss, Daniel; Schwan, Carsten

2012-01-01

Clostridium spiroforme produces the binary actin-ADP-ribosylating toxin CST (C. spiroforme toxin), which has been proposed to be responsible for diarrhea, enterocolitis, and eventually death, especially in rabbits. Here we report on the recombinant production of the enzyme component (CSTa) and the binding component (CSTb) of C. spiroforme toxin in Bacillus megaterium. By using the recombinant toxin components, we show that CST enters target cells via the lipolysis-stimulated lipoprotein receptor (LSR), which has been recently identified as the host cell receptor of the binary toxins Clostridium difficile transferase (CDT) and Clostridium perfringens iota toxin. Microscopic studies revealed that CST, but not the related Clostridium botulinum C2 toxin, colocalized with LSR during toxin uptake and traffic to endosomal compartments. Our findings indicate that CST shares LSR with C. difficile CDT and C. perfringens iota toxin as a host cell surface receptor. PMID:22252869

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

Proteomic Methods of Detection and Quantification of Protein Toxins.

PubMed

Duracova, Miloslava; Klimentova, Jana; Fucikova, Alena; Dresler, Jiri

2018-02-28

Biological toxins are a heterogeneous group of compounds that share commonalities with biological and chemical agents. Among them, protein toxins represent a considerable, diverse set. They cover a broad range of molecular weights from less than 1000 Da to more than 150 kDa. This review aims to compare conventional detection methods of protein toxins such as in vitro bioassays with proteomic methods, including immunoassays and mass spectrometry-based techniques and their combination. Special emphasis is given to toxins falling into a group of selected agents, according to the Centers for Disease Control and Prevention, such as Staphylococcal enterotoxins , Bacillus anthracis toxins, Clostridium botulinum toxins, Clostridium perfringens epsilon toxin, ricin from Ricinus communis , Abrin from Abrus precatorius or control of trade in dual-use items in the European Union, including lesser known protein toxins such as Viscumin from Viscum album . The analysis of protein toxins and monitoring for biological threats, i.e., the deliberate spread of infectious microorganisms or toxins through water, food, or the air, requires rapid and reliable methods for the early identification of these agents.

Proteomic Methods of Detection and Quantification of Protein Toxins

PubMed Central

Klimentova, Jana; Fucikova, Alena

2018-01-01

Biological toxins are a heterogeneous group of compounds that share commonalities with biological and chemical agents. Among them, protein toxins represent a considerable, diverse set. They cover a broad range of molecular weights from less than 1000 Da to more than 150 kDa. This review aims to compare conventional detection methods of protein toxins such as in vitro bioassays with proteomic methods, including immunoassays and mass spectrometry-based techniques and their combination. Special emphasis is given to toxins falling into a group of selected agents, according to the Centers for Disease Control and Prevention, such as Staphylococcal enterotoxins, Bacillus anthracis toxins, Clostridium botulinum toxins, Clostridium perfringens epsilon toxin, ricin from Ricinus communis, Abrin from Abrus precatorius or control of trade in dual-use items in the European Union, including lesser known protein toxins such as Viscumin from Viscum album. The analysis of protein toxins and monitoring for biological threats, i.e., the deliberate spread of infectious microorganisms or toxins through water, food, or the air, requires rapid and reliable methods for the early identification of these agents. PMID:29495560

Crystallization of isoelectrically homogeneous cholera toxin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Spangler, B.D.; Westbrook, E.M.

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.more » 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.« less

Botulinum toxin in trigeminal neuralgia.

PubMed

Castillo-Álvarez, Federico; Hernando de la Bárcena, Ignacio; Marzo-Sola, María Eugenia

2017-01-06

Trigeminal neuralgia is one of the most disabling facial pain syndromes, with a significant impact on patients' quality of life. Pharmacotherapy is the first choice for treatment but cases of drug resistance often require new strategies, among which various interventional treatments have been used. In recent years a new therapeutic strategy consisting of botulinum toxin has emerged, with promising results. We reviewed clinical cases and case series, open-label studies and randomized clinical trials examining the use of botulinum toxin for drug-refractory trigeminal neuralgia published in the literature. The administration of botulinum toxin has proven to be a safe and effective therapeutic strategy in patients with drug-refractory idiopathic trigeminal neuralgia, but many questions remain unanswered as to the precise role of botulinum toxin in the treatment of this disease. Copyright © 2016 Elsevier España, S.L.U. All rights reserved.

Collaborative Research Program on Seafood Toxins

DTIC Science & Technology

1988-08-14

Crystallographic Structures of Saxitoxins Cl and C2 Appendix C: Collaborative Research Program an Seafcod Toxins Progress Report on Ciguatera and Related...radioimmunoassay for PSP were also evalumted. The Hokama stick test for ciguatera toxin was also evaluated. 4. initiate Studies on the Accumulation...tco•d which caie a form of b-mnn poisoning referred to as ciguatera . The respcnsible toxins originate from ll1ular rine algae of the division

Legionella pneumophila Toxin, Isolation and Purification

DTIC Science & Technology

1981-01-01

which dis- plays an in vivo lethality. The purification procedures involve acid precipitation, gel chromatography, and preparative isotachophoresis. The...Chymotrypsinogen A, Ribonuclease A, and Apoprotinin as markers. Preparation of antiserum One milliqram amounts of protein from Le jonella acid ...RESULTS Toxin isolation Step 1: Acid precipitation of crude toxin. 1.0 N HCl acid was slowly added to rapidly stirred crude toxin until pH 3.5 was

Algal toxins

USGS Publications Warehouse

Creekmore, Lynn H.

1999-01-01

Periodic blooms of algae, including true algae, dinoflagellates, and cyanobacteria or blue-green algae have been reported in marine and freshwater bodies throughout the world. Although many blooms are merely an aesthetic nuisance, some species of algae produce toxins that kill fish, shellfish, humans, livestock and wildlife. Pigmented blooms of toxinproducing marine algae are often referred to as “red tides” (Fig. 36.1). Proliferations of freshwater toxin-producing cyanobacteria are simply called “cyanobacterial blooms” or “toxic algal blooms.” Cyanobacterial blooms initially appear green and may later turn blue, sometimes forming a “scum” in the water (Fig. 36.2).Although algal blooms historically have been considered a natural phenomenon, the frequency of occurrence of harmful algae appears to have increased in recent years. Agricultural runoff and other pollutants of freshwater and marine wetlands and water bodies have resulted in increased nutrient loading of phosphorus and nitrogen, thus providing conditions favorable to the growth of potentially toxic algae. The detrimental impact of red tides and cyanobacterial blooms on wetland, shore, and pelagic species has long been suspected but not often been substantiated because information on the effects of these toxins in fish and wildlife species is lacking and diagnostic tools are limited.

Microbially driven export of labile organic carbon from the Greenland ice sheet

NASA Astrophysics Data System (ADS)

Musilova, Michaela; Tranter, Martyn; Wadham, Jemma; Telling, Jon; Tedstone, Andrew; Anesio, Alexandre M.

2017-04-01

Glaciers and ice sheets are significant sources of dissolved organic carbon and nutrients to downstream subglacial and marine ecosystems. Climatically driven increases in glacial runoff are expected to intensify the impact of exported nutrients on local and regional downstream environments. However, the origin and bioreactivity of dissolved organic carbon from glacier surfaces are not fully understood. Here, we present simultaneous measurements of gross primary production, community respiration, dissolved organic carbon composition and export from different surface habitats of the Greenland ice sheet, throughout the ablation season. We found that microbial production was significantly correlated with the concentration of labile dissolved organic species in glacier surface meltwater. Further, we determined that freely available organic compounds made up 62% of the dissolved organic carbon exported from the glacier surface through streams. We therefore conclude that microbial communities are the primary driver for labile dissolved organic carbon production and recycling on glacier surfaces, and that glacier dissolved organic carbon export is dependent on active microbial processes during the melt season.

Labile dissolved organic carbon supply limits hyporheic denitrification

NASA Astrophysics Data System (ADS)

Zarnetske, Jay P.; Haggerty, Roy; Wondzell, Steven M.; Baker, Michelle A.

2011-12-01

We used an in situ steady state 15N-labeled nitrate (15NO3-) and acetate (AcO-) well-to-wells injection experiment to determine how the availability of labile dissolved organic carbon (DOC) as AcO-influences microbial denitrification in the hyporheic zone of an upland (third-order) agricultural stream. The experimental wells receiving conservative (Cl- and Br) and reactive (15NO3-) solute tracers had hyporheic median residence times of 7.0 to 13.1 h, nominal flowpath lengths of 0.7 to 3.7 m, and hypoxic conditions (<1.5 mg O2 L-1). All receiving wells demonstrated 15N2 production during ambient conditions, indicating that the hyporheic zone was an environment with active denitrification. The subsequent addition of AcO- stimulated more denitrification as evidenced by significant δ15N2 increases by factors of 2.7 to 26.1 in receiving wells and significant decreases of NO3- and DO in the two wells most hydrologically connected to the injection. The rate of nitrate removal in the hyporheic zone increased from 218 kg ha-1 yr-1 to 521 kg ha-1 yr-1 under elevated AcO- conditions. In all receiving wells, increases of bromide and 15N2 occurred without concurrent increases in AcO-, indicating that 100% of AcO- was retained or lost in the hyporheic zone. These results support the hypothesis that denitrification in anaerobic portions of the hyporheic zone is limited by labile DOC supply.

Botulinum Toxin: Pharmacology and Therapeutic Roles in Pain States.

PubMed

Patil, Shilpadevi; Willett, Olga; Thompkins, Terin; Hermann, Robert; Ramanathan, Sathish; Cornett, Elyse M; Fox, Charles J; Kaye, Alan David

2016-03-01

Botulinum toxin, also known as Botox, is produced by Clostridium botulinum, a gram-positive anaerobic bacterium, and botulinum toxin injections are among the most commonly practiced cosmetic procedures in the USA. Although botulinum toxin is typically associated with cosmetic procedures, it can be used to treat a variety of other conditions, including pain. Botulinum toxin blocks the release of acetylcholine from nerve endings to paralyze muscles and to decrease the pain response. Botulinum toxin has a long duration of action, lasting up to 5 months after initial treatment which makes it an excellent treatment for chronic pain patients. This manuscript will outline in detail why botulinum toxin is used as a successful treatment for pain in multiple conditions as well as outline the risks associated with using botulinum toxin in certain individuals. As of today, the only FDA-approved chronic condition that botulinum toxin can be used to treat is migraines and this is related to its ability to decrease muscle tension and increase muscle relaxation. Contraindications to botulinum toxin treatments are limited to a hypersensitivity to the toxin or an infection at the site of injection, and there are no known drug interactions with botulinum toxin. Botulinum toxin is an advantageous and effective alternative pain treatment and a therapy to consider for those that do not respond to opioid treatment. In summary, botulinum toxin is a relatively safe and effective treatment for individuals with certain pain conditions, including migraines. More research is warranted to elucidate chronic and long-term implications of botulinum toxin treatment as well as effects in pregnant, elderly, and adolescent patients.

Tumor Targeting and Drug Delivery by Anthrax Toxin.

PubMed

Bachran, Christopher; Leppla, Stephen H

2016-07-01

Anthrax toxin is a potent tripartite protein toxin from Bacillus anthracis. It is one of the two virulence factors and causes the disease anthrax. The receptor-binding component of the toxin, protective antigen, needs to be cleaved by furin-like proteases to be activated and to deliver the enzymatic moieties lethal factor and edema factor to the cytosol of cells. Alteration of the protease cleavage site allows the activation of the toxin selectively in response to the presence of tumor-associated proteases. This initial idea of re-targeting anthrax toxin to tumor cells was further elaborated in recent years and resulted in the design of many modifications of anthrax toxin, which resulted in successful tumor therapy in animal models. These modifications include the combination of different toxin variants that require activation by two different tumor-associated proteases for increased specificity of toxin activation. The anthrax toxin system has proved to be a versatile system for drug delivery of several enzymatic moieties into cells. This highly efficient delivery system has recently been further modified by introducing ubiquitin as a cytosolic cleavage site into lethal factor fusion proteins. This review article describes the latest developments in this field of tumor targeting and drug delivery.

Antibody-mediated inhibition of ricin toxin retrograde transport.

PubMed

Yermakova, Anastasiya; Klokk, Tove Irene; Cole, Richard; Sandvig, Kirsten; Mantis, Nicholas J

2014-04-08

Ricin is a member of the ubiquitous family of plant and bacterial AB toxins that gain entry into the cytosol of host cells through receptor-mediated endocytosis and retrograde traffic through the trans-Golgi network (TGN) and endoplasmic reticulum (ER). While a few ricin toxin-specific neutralizing monoclonal antibodies (MAbs) have been identified, the mechanisms by which these antibodies prevent toxin-induced cell death are largely unknown. Using immunofluorescence confocal microscopy and a TGN-specific sulfation assay, we demonstrate that 24B11, a MAb against ricin's binding subunit (RTB), associates with ricin in solution or when prebound to cell surfaces and then markedly enhances toxin uptake into host cells. Following endocytosis, however, toxin-antibody complexes failed to reach the TGN; instead, they were shunted to Rab7-positive late endosomes and LAMP-1-positive lysosomes. Monovalent 24B11 Fab fragments also interfered with toxin retrograde transport, indicating that neither cross-linking of membrane glycoproteins/glycolipids nor the recently identified intracellular Fc receptor is required to derail ricin en route to the TGN. Identification of the mechanism(s) by which antibodies like 24B11 neutralize ricin will advance our fundamental understanding of protein trafficking in mammalian cells and may lead to the discovery of new classes of toxin inhibitors and therapeutics for biodefense and emerging infectious diseases. IMPORTANCE Ricin is the prototypic member of the AB family of medically important plant and bacterial toxins that includes cholera and Shiga toxins. Ricin is also a category B biothreat agent. Despite ongoing efforts to develop vaccines and antibody-based therapeutics against ricin, very little is known about the mechanisms by which antibodies neutralize this toxin. In general, it is thought that antibodies simply prevent toxins from attaching to cell surface receptors or promote their clearance through Fc receptor (FcR)-mediated uptake

TOXINS FROM CYANOBACTERIA IN WATER

EPA Science Inventory

This project is part of a larger U. S. Environmental Protection Agency (EPA) effort, which includes the Office of Water, to investigate algal toxins in surface water supplies and drinking water. Toxins produced by cyanobacteria (blue-green algae) are among the most potent known ...

Can a toxin gene NAAT be used to predict toxin EIA and the severity of Clostridium difficile infection?

PubMed

Garvey, Mark I; Bradley, Craig W; Wilkinson, Martyn A C; Holden, Elisabeth

2017-01-01

Diagnosis of C. difficile infection (CDI) is controversial because of the many laboratory methods available and their lack of ability to distinguish between carriage, mild or severe disease. Here we describe whether a low C. difficile toxin B nucleic acid amplification test (NAAT) cycle threshold (CT) can predict toxin EIA, CDI severity and mortality. A three-stage algorithm was employed for CDI testing, comprising a screening test for glutamate dehydrogenase (GDH), followed by a NAAT, then a toxin enzyme immunoassay (EIA). All diarrhoeal samples positive for GDH and NAAT between 2012 and 2016 were analysed. The performance of the NAAT CT value as a classifier of toxin EIA outcome was analysed using a ROC curve; patient mortality was compared to CTs and toxin EIA via linear regression models. A CT value ≤26 was associated with ≥72% toxin EIA positivity; applying a logistic regression model we demonstrated an association between low CT values and toxin EIA positivity. A CT value of ≤26 was significantly associated ( p  = 0.0262) with increased one month mortality, severe cases of CDI or failure of first line treatment. The ROC curve probabilities demonstrated a CT cut off value of 26.6. Here we demonstrate that a CT ≤26 indicates more severe CDI and is associated with higher mortality. Samples with a low CT value are often toxin EIA positive, questioning the need for this additional EIA test. A CT ≤26 could be used to assess the potential for severity of CDI and guide patient treatment.

Monoclonal antibodies and toxins--a perspective on function and isotype.

PubMed

Chow, Siu-Kei; Casadevall, Arturo

2012-06-01

Antibody therapy remains the only effective treatment for toxin-mediated diseases. The development of hybridoma technology has allowed the isolation of monoclonal antibodies (mAbs) with high specificity and defined properties, and numerous mAbs have been purified and characterized for their protective efficacy against different toxins. This review summarizes the mAb studies for 6 toxins--Shiga toxin, pertussis toxin, anthrax toxin, ricin toxin, botulinum toxin, and Staphylococcal enterotoxin B (SEB)--and analyzes the prevalence of mAb functions and their isotypes. Here we show that most toxin-binding mAbs resulted from immunization are non-protective and that mAbs with potential therapeutic use are preferably characterized. Various common practices and caveats of protection studies are discussed, with the goal of providing insights for the design of future research on antibody-toxin interactions.

[Impact of Land Utilization Pattern on Distributing Characters of Labile Organic Carbon in Soil Aggregates in Jinyun Mountain].

PubMed

Li, Rui; Jiang, Chang-sheng; Hao, Qing-ju

2015-09-01

Four land utilization patterns were selected for this study in Jinyun mountain, including subtropical evergreen broad-leaved forest (abbreviation: forest), sloping farmland, orchard and abandoned land. Soil samples were taken every 10 cm in the depth of 60 cm soil and proportions of large macroaggregates (> 2 mm), small macroaggregates (0. 25-2 mm), microaggregates (0. 053 - 0. 25 mm) and silt + clay (<0. 053 mm) were obtained by wet sieving method to measure the content of organic carbon and labile organic carbon in each aggregate fraction and analyze impacts of land uses on organic carbon and labile organic carbon of soil aggregates. LOC content of four soil aggregates were significantly reduced with the increase of soil depth; in layers of 0-60 cm soil depth, our results showed that LOC contents of forest and abandoned land were higher than orchard and sloping farmland. Reserves of labile organic carbon were estimated by the same soil quality, it revealed that forest (3. 68 Mg.hm-2) > abandoned land (1. 73 Mg.hm-2) > orchard (1. 43 Mg.hm-2) >sloping farmland (0.54 Mg.hm-2) in large macroaggregates, abandoned land (7.77, 5. 01 Mg.hm-2) > forest (4. 96, 2.71 Mg.hm-2) > orchard (3. 33, 21. 10 Mg.hm-2) > sloping farmland (1. 68, 1. 35 Mg.hm-2) in small macroaggregates and microaggregates, and abandoned land(4. 32 Mg.hm-2) > orchard(4. 00 Mg.hm-2) > forest(3. 22 Mg.hm-2) > sloping farmland (2.37 Mg.hm-2) in silt + clay, forest and abandoned land were higher than orchard and sloping farmland in other three soil aggregates except silt + clay. It was observed that the level of organic carbon and labile organic carbon were decreased when bringing forest under cultivation to orchard or farmland, and augments on organic carbon and labile organic carbon were found after exchanging farmland to abandoned land. The most reverses of forest and abandoned land emerged in small macroaggregates, orchard and sloping farmland were in microaggregates. That was, during the

Clostridium botulinum C2 toxin--new insights into the cellular up-take of the actin-ADP-ribosylating toxin.

PubMed

Aktories, Klaus; Barth, Holger

2004-04-01

Clostridium botulinum C2 toxin is a member of the family of binary actin-ADP-ribosylating toxins. It consists of the enzyme component C2I, and the separated binding/translocation component C2II. Proteolytically activated C2II forms heptamers and binds to a carbohydrate cell surface receptor. After attachment of C2I, the toxin complex is endocytosed to reach early endosomes. At low pH of endosomes, C2II-heptamers insert into the membrane, form pores and deliver C2I into the cytosol. Here, C2I ADP-ribosylates actin at Arg177 to block actin polymerization and to induce depolymerization of actin filaments. The mini-review describes main properties of C2 toxin and discusses new findings on the involvement of chaperones in the up-take process of the toxin.

Toxins That Affect Voltage-Gated Sodium Channels.

PubMed

Ji, Yonghua

2017-10-26

Voltage-gated sodium channels (VGSCs) are critical in generation and conduction of electrical signals in multiple excitable tissues. Natural toxins, produced by animal, plant, and microorganisms, target VGSCs through diverse strategies developed over millions of years of evolutions. Studying of the diverse interaction between VGSC and VGSC-targeting toxins has been contributing to the increasing understanding of molecular structure and function, pharmacology, and drug development potential of VGSCs. This chapter aims to summarize some of the current views on the VGSC-toxin interaction based on the established receptor sites of VGSC for natural toxins.

The effect of acidification on the bioavailability and electrochemical lability of zinc in seawater

PubMed Central

Kim, Ja-Myung; Baars, Oliver

2016-01-01

A poorly studied but potentially important consequence of the CO2-induced acidification of the surface ocean is a possible change in the bioavailability of trace metals, which play a critical role in the productivity and population dynamics of marine ecosystems. We report laboratory and field experiments designed to compare quantitatively the effects of acidification on the bioavailability of Zn, a metal essential to the growth of phytoplankton and on the extent of its complexation by model and natural ligands. We observed a good correspondence between the effects of pH on the rate of Zn uptake by a model diatom and the chemical lability of Zn measured by anodic stripping voltammetry (ASV). In model laboratory systems, the chemical lability and the bioavailability of Zn could either increase or decrease at low pH depending on the mix of complexing ligands. In a sample of coastal surface water, we observed similar increases in the ASV-labile and bioavailable Zn concentrations upon acidification, a result contrary to previous observations. These results, which can likely be generalized to other bioactive trace metals, mutatis mutandis, demonstrate the intricacy of the effects of ocean acidification on the chemistry and the ecology of surface seawater. This article is part of the themed issue ‘Biological and climatic impacts of ocean trace element chemistry’. PMID:29035261

The effect of acidification on the bioavailability and electrochemical lability of zinc in seawater.

PubMed

Kim, Ja-Myung; Baars, Oliver; Morel, François M M

2016-11-28

A poorly studied but potentially important consequence of the CO 2 -induced acidification of the surface ocean is a possible change in the bioavailability of trace metals, which play a critical role in the productivity and population dynamics of marine ecosystems. We report laboratory and field experiments designed to compare quantitatively the effects of acidification on the bioavailability of Zn, a metal essential to the growth of phytoplankton and on the extent of its complexation by model and natural ligands. We observed a good correspondence between the effects of pH on the rate of Zn uptake by a model diatom and the chemical lability of Zn measured by anodic stripping voltammetry (ASV). In model laboratory systems, the chemical lability and the bioavailability of Zn could either increase or decrease at low pH depending on the mix of complexing ligands. In a sample of coastal surface water, we observed similar increases in the ASV-labile and bioavailable Zn concentrations upon acidification, a result contrary to previous observations. These results, which can likely be generalized to other bioactive trace metals, mutatis mutandis , demonstrate the intricacy of the effects of ocean acidification on the chemistry and the ecology of surface seawater.This article is part of the themed issue 'Biological and climatic impacts of ocean trace element chemistry'. © 2016 The Author(s).

Botulinum toxin for the treatment of bruxism.

PubMed

Tinastepe, Neslihan; Küçük, Burcu Bal; Oral, Koray

2015-10-01

Botulinum toxin, the most potent biological toxin, has been shown to be effective for a variety of disorders in several medical conditions, when used both therapeutically and cosmetically. In recent years, there has been a rising trend in the use of this pharmacological agent to control bruxing activity, despite its reported adverse effects. The aim of this review was to provide a brief overview to clarify the underlying essential ideas for the use of botulinum toxin in bruxism based on available scientific papers. An electronic literature search was performed to identify publications related to botulinum toxin and its use for bruxism in PubMed. Hand searching of relevant articles was also made to identify additional studies. Of the eleven identified studies, only two were randomized controlled trials, compared with the effectiveness of botulinum toxins on the reduction in the frequency of bruxism events and myofascial pain after injection. The authors of these studies concluded that botulinum toxin could be used as an effective treatment for reducing nocturnal bruxism and myofascial pain in patients with bruxism. Evidence-based research was limited on this topic. More randomized controlled studies are needed to confirm that botulinum toxin is safe and reliable for routine clinical use in bruxism.

Botulinum toxin for the treatment of bruxism.

PubMed

Tinastepe, Neslihan; Küçük, Burcu Bal; Oral, Koray

2014-08-14

Aims: Botulinum toxin, the most potent biological toxin, has been shown to be effective for a variety of disorders in several medical conditions, when used both therapeutically and cosmetically. In recent years, there has been a rising trend in the use of this pharmacological agent to control bruxing activity, despite its reported adverse effects. The aim of this review was to provide a brief overview to clarify the underlying essential ideas for the use of botulinum toxin in bruxism based on available scientific papers. Methodology: An electronic literature search was performed to identify publications related to botulinum toxin and its use for bruxism in PubMed. Hand searching of relevant articles was also made to identify additional studies. Results: Of the eleven identified studies, only two were randomized controlled trials, compared with the effectiveness of botulinum toxins on the reduction in the frequency of bruxism events and myofascial pain after injection. The authors of these studies concluded that botulinum toxin could be used as an effective treatment for reducing nocturnal bruxism and myofascial pain in patients with bruxism. Conclusion: Evidence-based research was limited on this topic. More randomized controlled studies are needed to confirm that botulinum toxin is safe and reliable for routine clinical use in bruxism.

Cyanobacterial toxins: risk management for health protection

DOE Office of Scientific and Technical Information (OSTI.GOV)

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 riskmore » 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.« less

Sewage sludge amendment and inoculation with plant-parasitic nematodes do not facilitate the internalization of Salmonella Typhimurium LT2 in lettuce plants.

PubMed

Fornefeld, Eva; Baklawa, Mohamed; Hallmann, Johannes; Schikora, Adam; Smalla, Kornelia

2018-05-01

Contamination of fruits and vegetables with Salmonella is a serious threat to human health. In order to prevent possible contaminations of fresh produce it is necessary to identify the contributing ecological factors. In this study we investigated whether the addition of sewage sludge or the presence of plant-parasitic nematodes foster the internalization of Salmonella enterica serovar Typhimurium LT2 into lettuce plants, posing a potential threat for human health. Greenhouse experiments were conducted to investigate whether the amendment of sewage sludge to soil or the presence of plant-parasitic nematodes Meloidogyne hapla or Pratylenchus crenatus promote the internalization of S. Typhimurium LT2 from soil into the edible part of lettuce plants. Unexpectedly, numbers of cultivable S. Typhimurium LT2 decreased faster in soil with sewage sludge than in control soil but not in root samples. Denaturing gradient gel electrophoresis analysis revealed shifts of the soil bacterial communities in response to sewage sludge amendment and time. Infection and proliferation of nematodes inside plant roots were observed but did not influence the number of cultivable S. Typhimurium LT2 in the root samples or in soil. S. Typhimurium LT2 was not detected in the leaf samples 21 and 49 days after inoculation. The results indicate that addition of sewage sludge, M. hapla or P. crenatus to soil inoculated with S. Typhimurium LT2 did not result in an improved survival in soil or internalization of lettuce plants. Copyright © 2017. Published by Elsevier Ltd.

Binding of Diphtheria Toxin to Phospholipids in Liposomes

NASA Astrophysics Data System (ADS)

Alving, Carl R.; Iglewski, Barbara H.; Urban, Katharine A.; Moss, Joel; Richards, Roberta L.; Sadoff, Jerald C.

1980-04-01

Diphtheria toxin bound to the phosphate portion of some, but not all, phospholipids in liposomes. Liposomes consisting of dimyristoyl phosphatidylcholine and cholesterol did not bind toxin. Addition of 20 mol% (compared to dimyristoyl phosphatidylcholine) of dipalmitoyl phosphatidic acid, dicetyl phosphate, phosphatidylinositol phosphate, cardiolipin, or phosphatidylserine in the liposomes resulted in substantial binding of toxin. Inclusion of phosphatidylinositol in dimyristol phosphatidylcholine / cholesterol liposomes did not result in toxin binding. The calcium salt of dipalmitoyl phosphatidic acid was more effective than the sodium salt, and the highest level of binding occurred with liposomes consisting only of dipalmitoyl phosphatidic acid (calcium salt) and cholesterol. Binding of toxin to liposomes was dependent on pH, and the pattern of pH dependence varied with liposomes having different compositions. Incubation of diphtheria toxin with liposomes containing dicetyl phosphate resulted in maximal binding at pH 3.6, whereas binding to liposomes containing phosphatidylinositol phosphate was maximal above pH 7. Toxin did not bind to liposomes containing 20 mol% of a free fatty acid (palmitic acid) or a sulfated lipid (3-sulfogalactosylceramide). Toxin binding to dicetyl phosphate or phosphatidylinositol phosphate was inhibited by UTP, ATP, phosphocholine, or p-nitrophenyl phosphate, but not by uracil. We conclude that (a) diphtheria toxin binds specifically to the phosphate portion of certain phospholipids, (b) binding to phospholipids in liposomes is dependent on pH, but is not due only to electrostatic interaction, and (c) binding may be strongly influenced by the composition of adjacent phospholipids that do not bind toxin. We propose that a minor membrane phospholipid (such as phosphatidylinositol phosphate or phosphatidic acid), or that some other phosphorylated membrane molecule (such as a phosphoprotein) may be important in the initial binding of

Affective lability mediates the association between childhood trauma and suicide attempts, mixed episodes and co-morbid anxiety disorders in bipolar disorders.

PubMed

Aas, M; Henry, C; Bellivier, F; Lajnef, M; Gard, S; Kahn, J-P; Lagerberg, T V; Aminoff, S R; Bjella, T; Leboyer, M; Andreassen, O A; Melle, I; Etain, B

2017-04-01

Many studies have shown associations between a history of childhood trauma and more severe or complex clinical features of bipolar disorders (BD), including suicide attempts and earlier illness onset. However, the psychopathological mechanisms underlying these associations are still unknown. Here, we investigated whether affective lability mediates the relationship between childhood trauma and the severe clinical features of BD. A total of 342 participants with BD were recruited from France and Norway. Diagnosis and clinical characteristics were assessed using the Diagnostic Interview for Genetic Studies (DIGS) or the Structured Clinical Interview for DSM-IV Axis I disorders (SCID-I). Affective lability was measured using the short form of the Affective Lability Scale (ALS-SF). A history of childhood trauma was assessed using the Childhood Trauma Questionnaire (CTQ). Mediation analyses were performed using the SPSS process macro. Using the mediation model and covariation for the lifetime number of major mood episodes, affective lability was found to statistically mediate the relationship between childhood trauma experiences and several clinical variables, including suicide attempts, mixed episodes and anxiety disorders. No significant mediation effects were found for rapid cycling or age at onset. Our data suggest that affective lability may represent a psychological dimension that mediates the association between childhood traumatic experiences and the risk of a more severe or complex clinical expression of BD.

Drooling in Parkinson's disease: A randomized controlled trial of incobotulinum toxin A and meta-analysis of Botulinum toxins.

PubMed

Narayanaswami, Pushpa; Geisbush, Thomas; Tarulli, Andrew; Raynor, Elizabeth; Gautam, Shiva; Tarsy, Daniel; Gronseth, Gary

2016-09-01

Botulinum toxins are a therapeutic option for drooling in Parkinson's Disease (PD). The aims of this study were to: 1. evaluate the efficacy of incobotulinum toxin A for drooling in PD. 2. Perform a meta-analysis of studies of Botulinum toxins for drooling in PD. 1. Primary study: Randomized, double blind, placebo controlled, cross over trial. Incobotulinum toxin (100 units) or saline was injected into the parotid (20 units) and submandibular (30 units) glands. Subjects returned monthly for three evaluations after each injection. Outcome measures were saliva weight and Drooling Frequency and Severity Scale. 2. Systematic review of literature, followed by inverse variance meta-analyses using random effects models. 1. Primary Study: Nine of 10 subjects completed both arms. There was no significant change in the primary outcome of saliva weight one month after injection in the treatment period compared to placebo period (mean difference, gm ± SD: -0.194 ± 0.61, range: -1.28 to 0.97, 95% CI -0.71 to 0.32). Secondary outcomes also did not change. 2. Meta-analysis of six studies demonstrated significant benefit of Botulinum toxin on functional outcomes (effect size, Cohen's d: -1.32, CI -1.86 to -0.78). The other studies used a higher dose of Botulinum toxin A into the parotid glands. This study did not demonstrate efficacy of incobotulinum toxin A for drooling in PD, but lacked precision to exclude moderate benefit. The parotid/submandibular dose-ratio may have influenced results. Studies evaluating higher doses of incobotulinum toxin A into the parotid glands may be useful. Copyright © 2016 Elsevier Ltd. All rights reserved.

Array biosensor for detection of toxins

NASA Technical Reports Server (NTRS)

Ligler, Frances S.; Taitt, Chris Rowe; Shriver-Lake, Lisa C.; Sapsford, Kim E.; Shubin, Yura; Golden, Joel P.

2003-01-01

The array biosensor is capable of detecting multiple targets rapidly and simultaneously on the surface of a single waveguide. Sandwich and competitive fluoroimmunoassays have been developed to detect high and low molecular weight toxins, respectively, in complex samples. Recognition molecules (usually antibodies) were first immobilized in specific locations on the waveguide and the resultant patterned array was used to interrogate up to 12 different samples for the presence of multiple different analytes. Upon binding of a fluorescent analyte or fluorescent immunocomplex, the pattern of fluorescent spots was detected using a CCD camera. Automated image analysis was used to determine a mean fluorescence value for each assay spot and to subtract the local background signal. The location of the spot and its mean fluorescence value were used to determine the toxin identity and concentration. Toxins were measured in clinical fluids, environmental samples and foods, with minimal sample preparation. Results are shown for rapid analyses of staphylococcal enterotoxin B, ricin, cholera toxin, botulinum toxoids, trinitrotoluene, and the mycotoxin fumonisin. Toxins were detected at levels as low as 0.5 ng mL(-1).

MaLT - Combined Motor and Language Therapy Tool for Brain Injury Patients Using Kinect.

PubMed

Wairagkar, Maitreyee; McCrindle, Rachel; Robson, Holly; Meteyard, Lotte; Sperrin, Malcom; Smith, Andy; Pugh, Moyra

2017-03-23

The functional connectivity and structural proximity of elements of the language and motor systems result in frequent co-morbidity post brain injury. Although rehabilitation services are becoming increasingly multidisciplinary and "integrated", treatment for language and motor functions often occurs in isolation. Thus, behavioural therapies which promote neural reorganisation do not reflect the high intersystem connectivity of the neurologically intact brain. As such, there is a pressing need for rehabilitation tools which better reflect and target the impaired cognitive networks. The objective of this research is to develop a combined high dosage therapy tool for language and motor rehabilitation. The rehabilitation therapy tool developed, MaLT (Motor and Language Therapy), comprises a suite of computer games targeting both language and motor therapy that use the Kinect sensor as an interaction device. The games developed are intended for use in the home environment over prolonged periods of time. In order to track patients' engagement with the games and their rehabilitation progress, the game records patient performance data for the therapist to interrogate. MaLT incorporates Kinect-based games, a database of objects and language parameters, and a reporting tool for therapists. Games have been developed that target four major language therapy tasks involving single word comprehension, initial phoneme identification, rhyme identification and a naming task. These tasks have 8 levels each increasing in difficulty. A database of 750 objects is used to programmatically generate appropriate questions for the game, providing both targeted therapy and unique gameplay every time. The design of the games has been informed by therapists and by discussions with a Public Patient Involvement (PPI) group. Pilot MaLT trials have been conducted with three stroke survivors for the duration of 6 to 8 weeks. Patients' performance is monitored through MaLT's reporting facility

Botulinum toxin for the treatment of strabismus.

PubMed

Rowe, Fiona J; Noonan, Carmel P

2017-03-02

The use of botulinum toxin as an investigative and treatment modality for strabismus is well reported in the medical literature. However, it is unclear how effective it is in comparison to other treatment options for strabismus. The primary objective was to examine the efficacy of botulinum toxin therapy in the treatment of strabismus compared with alternative conservative or surgical treatment options. This review sought to ascertain those types of strabismus that particularly benefit from the use of botulinum toxin as a treatment option (such as small angle strabismus or strabismus with binocular potential, i.e. the potential to use both eyes together as a pair). The secondary objectives were to investigate the dose effect and complication rates associated with botulinum toxin. We searched CENTRAL (which contains the Cochrane Eyes and Vision Trials Register) (2016, Issue 6), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to July 2016), Embase (January 1980 to July 2016), Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to July 2016), the ISRCTN registry (www.isrctn.com/editAdvancedSearch), ClinicalTrials.gov (www.clinicaltrials.gov), and the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 11 July 2016. We handsearched the British and Irish Orthoptic Journal, Australian Orthoptic Journal, proceedings of the European Strabismological Association (ESA), International Strabismological Association (ISA) and International Orthoptic Association (IOA) (www.liv.ac.uk/orthoptics/research/search.htm) and American Academy of Paediatric Ophthalmology and Strabismus meetings (AAPOS). We contacted researchers who are active in this field for information about further

Mechanisms of the cytopathic action of actin-ADP-ribosylating toxins.

PubMed

Aktories, K; Wegner, A

1992-10-01

Clostridium botulinum C2 toxin, Clostridium perfringens iota toxin, and Clostridium spiroforme toxin ADP-ribosylate actin monomers. Toxin-induced ADP-ribosylation disturbs the cellular equilibrium between monomeric and polymeric actin and traps monomeric actin in its unpolymerized form, thereby depolymerizing actin filaments and destroying the microfilament network. Furthermore, the toxins ADP-ribosylate gelsolin actin complexes. These modifications may contribute to the cytopathic action of the toxins.

Relationship between the lability of sediment-bound Cd and its bioaccumulation in edible oyster.

PubMed

Chakraborty, Parthasarathi; Ramteke, Darwin; Chakraborty, Sucharita; Chennuri, Kartheek; Bardhan, Pratirupa

2015-11-15

A linkage between Cd speciation in sediments and its bioaccumulation in edible oyster (Crassostrea sp.) from a tropical estuarine system was established. Bioaccumulation of Cd in edible oyster increased with the increasing lability and dissociation rate constants of Cd-sediment complexes in the bottom sediments. Total Cd concentration in sediment was not a good indicator of Cd-bioavailability. Increasing trace metal competition in sediments increased lability and bioavailability of Cd in the tropical estuarine sediment. Low thermodynamic stability and high bioavailability of Cd in the estuarine sediment were responsible for high bioaccumulation of Cd in edible oysters (3.2-12.2mgkg(-1)) even though the total concentration of Cd in the bottom sediment was low (0.17-0.49mgkg(-1)). Copyright © 2015 Elsevier Ltd. All rights reserved.

Botulinum Toxin Use in Pediatric Plastic Surgery.

PubMed

Fu, Katherine J; Teichgraeber, John F; Greives, Matthew R

2016-11-01

Botulinum toxin has increasingly become a prevalent treatment option for a wide range of conditions, many of which have their roots in plastic surgery and have been well studied. In adults, chronic headache, hyperhidrosis, and facial muscular hypertrophy have been effectively treated with botulinum toxin, and emerging studies have begun looking at its efficacy in children, as well. Successful treatment of spasticity and muscular contraction has allowed for the creation of safety profiles and dosage guidelines for botulinum toxin usage in children. The expanded indications for its use have since flourished in all arenas of pediatric care, including plastic surgery. Recent studies have described the use of botulinum toxin as an adjunct to the treatment of congenital torticollis and cleft lip. This review discusses the various applications of botulinum toxin for pediatric patients in the field of plastic surgery.

Short toxin-like proteins abound in Cnidaria genomes.

PubMed

Tirosh, Yitshak; Linial, Itai; Askenazi, Manor; Linial, Michal

2012-11-16

Cnidaria is a rich phylum that includes thousands of marine species. In this study, we focused on Anthozoa and Hydrozoa that are represented by the Nematostella vectensis (Sea anemone) and Hydra magnipapillata genomes. We present a method for ranking the toxin-like candidates from complete proteomes of Cnidaria. Toxin-like functions were revealed using ClanTox, a statistical machine-learning predictor trained on ion channel inhibitors from venomous animals. Fundamental features that were emphasized in training ClanTox include cysteines and their spacing along the sequences. Among the 83,000 proteins derived from Cnidaria representatives, we found 170 candidates that fulfill the properties of toxin-like-proteins, the vast majority of which were previously unrecognized as toxins. An additional 394 short proteins exhibit characteristics of toxin-like proteins at a moderate degree of confidence. Remarkably, only 11% of the predicted toxin-like proteins were previously classified as toxins. Based on our prediction methodology and manual annotation, we inferred functions for over 400 of these proteins. Such functions include protease inhibitors, membrane pore formation, ion channel blockers and metal binding proteins. Many of the proteins belong to small families of paralogs. We conclude that the evolutionary expansion of toxin-like proteins in Cnidaria contributes to their fitness in the complex environment of the aquatic ecosystem.

Stand-scale correspondence in empirical and simulated labile carbohydrates in loblolly pine

Treesearch

David A. Sampson; Kurt H. Johnsen; Kim H. Ludovici; Timothy J. Albaugh; Chris A. Maier

2001-01-01

As investment into intensive forestry increases, the potential trade-offs between productivity and sustainability should be scrutinized. Because of their important role in internal carbon (C) budgets, labile C pools may provide a measure of the potential ability of trees and stands to respond to stress. We modified the process model BIOMASS to...

In vivo bioluminescence imaging of labile iron accumulation in a murine model of Acinetobacter baumannii infection.

PubMed

Aron, Allegra T; Heffern, Marie C; Lonergan, Zachery R; Vander Wal, Mark N; Blank, Brian R; Spangler, Benjamin; Zhang, Yaofang; Park, Hyo Min; Stahl, Andreas; Renslo, Adam R; Skaar, Eric P; Chang, Christopher J

2017-11-28

Iron is an essential metal for all organisms, yet disruption of its homeostasis, particularly in labile forms that can contribute to oxidative stress, is connected to diseases ranging from infection to cancer to neurodegeneration. Iron deficiency is also among the most common nutritional deficiencies worldwide. To advance studies of iron in healthy and disease states, we now report the synthesis and characterization of iron-caged luciferin-1 (ICL-1), a bioluminescent probe that enables longitudinal monitoring of labile iron pools (LIPs) in living animals. ICL-1 utilizes a bioinspired endoperoxide trigger to release d-aminoluciferin for selective reactivity-based detection of Fe 2+ with metal and oxidation state specificity. The probe can detect physiological changes in labile Fe 2+ levels in live cells and mice experiencing iron deficiency or overload. Application of ICL-1 in a model of systemic bacterial infection reveals increased iron accumulation in infected tissues that accompany transcriptional changes consistent with elevations in both iron acquisition and retention. The ability to assess iron status in living animals provides a powerful technology for studying the contributions of iron metabolism to physiology and pathology.

Affective lability and difficulties with regulation are differentially associated with amygdala and prefrontal response in women with Borderline Personality Disorder

PubMed Central

Silvers, Jennifer A.; Hubbard, Alexa D.; Biggs, Emily; Shu, Jocelyn; Fertuck, Eric; Chaudhury, Sadia; Grunebaum, Michael F.; Weber, Jochen; Kober, Hedy; Chesin, Megan; Brodsky, Beth S.; Koenigsberg, Harold; Ochsner, Kevin N.; Stanley, Barbara

2016-01-01

The present neuroimaging study investigated two aspects of difficulties with emotion associated with Borderline Personality Disorder (BPD1): affective lability and difficulty regulating emotion. While these two characteristics have been previously linked to BPD symptomology, it remains unknown whether individual differences in affective lability and emotion regulation difficulties are subserved by distinct neural substrates within a BPD sample. To address this issue, sixty women diagnosed with BPD were scanned while completing a task that assessed baseline emotional reactivity as well as top-down emotion regulation. More affective instability, as measured by the Affective Lability Scale (ALS2), positively correlated with greater amygdala responses on trials assessing emotional reactivity. Greater difficulties with regulating emotion, as measured by the Difficulties with Emotion Regulation Scale (DERS3), was negatively correlated with left inferior frontal gyrus (IFG4) recruitment on trials assessing regulatory ability. These findings suggest that, within a sample of individuals with BPD, greater bottom-up amygdala activity is associated with heightened affective lability. By contrast, difficulties with emotion regulation are related to reduced IFG recruitment during emotion regulation. These results point to distinct neural mechanisms for different aspects of BPD symptomology. PMID:27379614

Oral rice-based vaccine induces passive and active immunity against enterotoxigenic E. coli-mediated diarrhea in pigs.

PubMed

Takeyama, Natsumi; Yuki, Yoshikazu; Tokuhara, Daisuke; Oroku, Kazuki; Mejima, Mio; Kurokawa, Shiho; Kuroda, Masaharu; Kodama, Toshiaki; Nagai, Shinya; Ueda, Susumu; Kiyono, Hiroshi

2015-09-22

Enterotoxigenic Escherichia coli (ETEC) causes severe diarrhea in both neonatal and weaned pigs. Because the cholera toxin B subunit (CTB) has a high level of amino acid identity to the ETEC heat-labile toxin (LT) B-subunit (LTB), we selected MucoRice-CTB as a vaccine candidate against ETEC-induced pig diarrhea. When pregnant sows were orally immunized with MucoRice-CTB, increased amounts of antigen-specific IgG and IgA were produced in their sera. CTB-specific IgG was secreted in the colostrum and transferred passively to the sera of suckling piglets. IgA antibodies in the colostrum and milk remained high with a booster dose after farrowing. Additionally, when weaned minipigs were orally immunized with MucoRice-CTB, production of CTB-specific intestinal SIgA, as well as systemic IgG and IgA, was induced. To evaluate the cross-protective effect of MucoRice-CTB against ETEC diarrhea, intestinal loop assay with ETEC was conducted. The fluid volume accumulated in the loops of minipigs immunized with MucoRice-CTB was significantly lower than that in control minipigs, indicating that MucoRice-CTB-induced cross-reactive immunity could protect weaned pigs from diarrhea caused by ETEC. MucoRice-CTB could be a candidate oral vaccine for inducing both passive and active immunity to protect both suckling and weaned piglets from ETEC diarrhea. Copyright © 2015 Elsevier Ltd. All rights reserved.

Potential pathogens, antimicrobial patterns and genotypic diversity of Escherichia coli isolates in constructed wetlands treating swine wastewater.

PubMed

Ibekwe, A M; Murinda, Shelton E; DebRoy, Chitrita; Reddy, Gudigopura B

2016-02-01

Escherichia coli populations originating from swine houses through constructed wetlands were analyzed for potential pathogens, antimicrobial susceptibility patterns, and genotypic diversity. Escherichia coli isolates (n = 493) were screened for the presence of the following virulence genes: stx1, stx2 and eae (Shiga toxin-producing E. coli [STEC]), heat-labile enterotoxin (LT) genes and heat stable toxin STa and STb (enterotoxigenic E. coli (ETEC), cytotoxin necrotizing factors 1 and 2 (cnf1 and cnf2 [necrotoxigenic E. coli- NTEC]), as well as O and H antigens, and the presence of the antibiotic resistance genes blaTEM, blaSHV, blaCMY-2, tet A, tet B, tet C, mph(A), aadA, StrA/B, sul1, sul2 and sul3. The commensal strains were further screened for 16 antimicrobials and characterized by BOX AIR-1 PCR for unique genotypes. The highest antibiotic resistance prevalence was for tetracycline, followed by erythromycin, ampicillin, streptomycin, sulfisoxazole and kanamycin. Our data showed that most of the isolates had high distribution of single or multidrug-resistant (MDR) genotypes. Therefore, the occurrence of MDR E. coli in the wetland is a matter of great concern due to possible transfer of resistance genes from nonpathogenic to pathogenic strains or vice versa in the environment. Published by Oxford University Press on behalf of FEMS 2016. This work is written by (a) US Government employee(s) and is in the public domain in the US.

Clostridium perfringens epsilon toxin inhibits the gastrointestinal transit in mice.

PubMed

Losada-Eaton, D M; Fernandez-Miyakawa, M E

2010-12-01

Epsilon toxin produced by Clostridium perfringens type B and D is a potent toxin that is responsible for a highly fatal enterotoxemia in sheep and goats. In vitro, epsilon toxin produces contraction of the rat ileum as the result of an indirect action, presumably mediated through the autonomic nervous system. To examine the impact of epsilon toxin in the intestinal transit, gastric emptying (GE) and gastrointestinal transit (GIT) were evaluated after intravenous and oral administration of epsilon toxin in mice. Orally administered epsilon toxin produced a delay on the GIT. Inhibition of the small intestinal transit was observed as early as 1 h after the toxin was administered orally but the effects were not observed after 1 week. Epsilon toxin also produced an inhibition in GE and a delay on the GIT when relatively high toxin concentrations were given intravenously. These results indicate that epsilon toxin administered orally or intravenously to mice transitorily inhibits the GIT. The delay in the GIT induced by epsilon toxin could be relevant in the pathogenesis of C. perfringens type B and D enterotoxemia. Copyright © 2010 Elsevier Ltd. All rights reserved.

Molecular basis of toxicity of Clostridium perfringens epsilon toxin.

PubMed

Bokori-Brown, Monika; Savva, Christos G; Fernandes da Costa, Sérgio P; Naylor, Claire E; Basak, Ajit K; Titball, Richard W

2011-12-01

Clostridium perfringens ε-toxin is produced by toxinotypes B and D strains. The toxin is the aetiological agent of dysentery in newborn lambs but is also associated with enteritis and enterotoxaemia in goats, calves and foals. It is considered to be a potential biowarfare or bioterrorism agent by the US Government Centers for Disease Control and Prevention. The relatively inactive 32.9 kDa prototoxin is converted to active mature toxin by proteolytic cleavage, either by digestive proteases of the host, such as trypsin and chymotrypsin, or by C. perfringens λ-protease. In vivo, the toxin appears to target the brain and kidneys, but relatively few cell lines are susceptible to the toxin, and most work has been carried out using Madin-Darby canine kidney (MDCK) cells. The binding of ε-toxin to MDCK cells and rat synaptosomal membranes is associated with the formation of a stable, high molecular weight complex. The crystal structure of ε-toxin reveals similarity to aerolysin from Aeromonas hydrophila, parasporin-2 from Bacillus thuringiensis and a lectin from Laetiporus sulphureus. Like these toxins, ε-toxin appears to form heptameric pores in target cell membranes. The exquisite specificity of the toxin for specific cell types suggests that it binds to a receptor found only on these cells. © 2011 The Authors Journal compilation © 2011 FEBS.

Botulinum toxin for vaginismus treatment.

PubMed

Ferreira, Juliana Rocha; Souza, Renan Pedra

2012-01-01

Vaginismus is characterized by recurrent or persistent involuntary contraction of the perineal muscles surrounding the outer third of the vagina when penile, finger, tampon, or speculum penetration is attempted. Recent results have suggested the use of botulinum toxin for the treatment of vaginismus. Here, we assessed previously published data to evaluate the therapeutic effectiveness of botulinum toxin for vaginismus. We have carried out a systematic review followed by a meta-analysis. Our results indicate that botulinum toxin is an effective therapeutic option for patients with vaginismus (pooled odds ratio of 8.723 with 95% confidence interval limits of 1.942 and 39.162, p = 0.005). This may hold particularly true in treatment-refractory patients because most of the studies included in this meta-analysis have enrolled these subjects in their primary analysis. Botulinum toxin appears to bea reasonable intervention for vaginismus. However, this conclusion should be read carefully because of the deficiency of placebo-controlled randomized clinical trials and the quality issues presented in the existing ones.

Clostridium Perfringens Toxins Involved in Mammalian Veterinary Diseases

PubMed Central

Uzal, F. A.; Vidal, J. E.; McClane, B. A.; Gurjar, A. A.

2013-01-01

Clostridium perfringens is a gram-positive anaerobic rod that is classified into 5 toxinotypes (A, B, C, D, and E) according to the production of 4 major toxins, namely alpha (CPA), beta (CPB), epsilon (ETX) and iota (ITX). However, this microorganism can produce up to 16 toxins in various combinations, including lethal toxins such as perfringolysin O (PFO), enterotoxin (CPE), and beta2 toxin (CPB2). Most diseases caused by this microorganism are mediated by one or more of these toxins. The role of CPA in intestinal disease of mammals is controversial and poorly documented, but there is no doubt that this toxin is essential in the production of gas gangrene of humans and several animal species. CPB produced by C. perfringens types B and C is responsible for necrotizing enteritis and enterotoxemia mainly in neonatal individuals of several animal species. ETX produced by C. perfringens type D is responsible for clinical signs and lesions of enterotoxemia, a predominantly neurological disease of sheep and goats. The role of ITX in disease of animals is poorly understood, although it is usually assumed that the pathogenesis of intestinal diseases produced by C. perfringens type E is mediated by this toxin. CPB2, a necrotizing and lethal toxin that can be produced by all types of C. perfringens, has been blamed for disease in many animal species, but little information is currently available to sustain or rule out this claim. CPE is an important virulence factor for C. perfringens type A gastrointestinal disease in humans and dogs; however, the data implicating CPE in other animal diseases remains ambiguous. PFO does not seem to play a direct role as the main virulence factor for animal diseases, but it may have a synergistic role with CPA-mediated gangrene and ETX-mediated enterotoxemia. The recent improvement of animal models for C. perfringens infection and the use of toxin gene knock-out mutants have demonstrated the specific pathogenic role of several toxins of C

Single toxin dose-response models revisited

DOE Office of Scientific and Technical Information (OSTI.GOV)

Demidenko, Eugene, E-mail: eugened@dartmouth.edu

The goal of this paper is to offer a rigorous analysis of the sigmoid shape single toxin dose-response relationship. The toxin efficacy function is introduced and four special points, including maximum toxin efficacy and inflection points, on the dose-response curve are defined. The special points define three phases of the toxin effect on mortality: (1) toxin concentrations smaller than the first inflection point or (2) larger then the second inflection point imply low mortality rate, and (3) concentrations between the first and the second inflection points imply high mortality rate. Probabilistic interpretation and mathematical analysis for each of the fourmore » models, Hill, logit, probit, and Weibull is provided. Two general model extensions are introduced: (1) the multi-target hit model that accounts for the existence of several vital receptors affected by the toxin, and (2) model with a nonzero mortality at zero concentration to account for natural mortality. Special attention is given to statistical estimation in the framework of the generalized linear model with the binomial dependent variable as the mortality count in each experiment, contrary to the widespread nonlinear regression treating the mortality rate as continuous variable. The models are illustrated using standard EPA Daphnia acute (48 h) toxicity tests with mortality as a function of NiCl or CuSO{sub 4} toxin. - Highlights: • The paper offers a rigorous study of a sigmoid dose-response relationship. • The concentration with highest mortality rate is rigorously defined. • A table with four special points for five morality curves is presented. • Two new sigmoid dose-response models have been introduced. • The generalized linear model is advocated for estimation of sigmoid dose-response relationship.« less

Dinoflagellate Toxins Responsible for Ciguatera Food Poisoning

DTIC Science & Technology

1988-12-10

0 AD DINOFLAGELLATE TOXINS RESPONSIBLE FOR CIGUATERA FOOD POISONING Annual Summary Report Donald M. Miller December 10, 1988 Supported by US ARMY...Maryland 21701-5012 62770A 62770A871 AA 377 11. TITLE (Include Security Classification) Dinoflagellate Toxins Responsible for Ciguatera Poisoning 12...block number) FIELD GROUP SUB-GROUP Ciguatera ; Toxins; Inhibitor; RA I; Dinoflagellates; 06 03 Mass Culture; Purification󈧊 j 01 19 ABSTRACT

Clostridial binary toxins: iota and C2 family portraits.

PubMed

Stiles, Bradley G; Wigelsworth, Darran J; Popoff, Michel R; Barth, Holger

2011-01-01

There are many pathogenic Clostridium species with diverse virulence factors that include protein toxins. Some of these bacteria, such as C. botulinum, C. difficile, C. perfringens, and C. spiroforme, cause enteric problems in animals as well as humans. These often fatal diseases can partly be attributed to binary protein toxins that follow a classic AB paradigm. Within a targeted cell, all clostridial binary toxins destroy filamentous actin via mono-ADP-ribosylation of globular actin by the A component. However, much less is known about B component binding to cell-surface receptors. These toxins share sequence homology amongst themselves and with those produced by another Gram-positive, spore-forming bacterium also commonly associated with soil and disease: Bacillus anthracis. This review focuses upon the iota and C2 families of clostridial binary toxins and includes: (1) basics of the bacterial source; (2) toxin biochemistry; (3) sophisticated cellular uptake machinery; and (4) host-cell responses following toxin-mediated disruption of the cytoskeleton. In summary, these protein toxins aid diverse enteric species within the genus Clostridium.

Clostridial Binary Toxins: Iota and C2 Family Portraits

PubMed Central

Stiles, Bradley G.; Wigelsworth, Darran J.; Popoff, Michel R.; Barth, Holger

2011-01-01

There are many pathogenic Clostridium species with diverse virulence factors that include protein toxins. Some of these bacteria, such as C. botulinum, C. difficile, C. perfringens, and C. spiroforme, cause enteric problems in animals as well as humans. These often fatal diseases can partly be attributed to binary protein toxins that follow a classic AB paradigm. Within a targeted cell, all clostridial binary toxins destroy filamentous actin via mono-ADP-ribosylation of globular actin by the A component. However, much less is known about B component binding to cell-surface receptors. These toxins share sequence homology amongst themselves and with those produced by another Gram-positive, spore-forming bacterium also commonly associated with soil and disease: Bacillus anthracis. This review focuses upon the iota and C2 families of clostridial binary toxins and includes: (1) basics of the bacterial source; (2) toxin biochemistry; (3) sophisticated cellular uptake machinery; and (4) host–cell responses following toxin-mediated disruption of the cytoskeleton. In summary, these protein toxins aid diverse enteric species within the genus Clostridium. PMID:22919577

Short Toxin-like Proteins Abound in Cnidaria Genomes

PubMed Central

Tirosh, Yitshak; Linial, Itai; Askenazi, Manor; Linial, Michal

2012-01-01

Cnidaria is a rich phylum that includes thousands of marine species. In this study, we focused on Anthozoa and Hydrozoa that are represented by the Nematostella vectensis (Sea anemone) and Hydra magnipapillata genomes. We present a method for ranking the toxin-like candidates from complete proteomes of Cnidaria. Toxin-like functions were revealed using ClanTox, a statistical machine-learning predictor trained on ion channel inhibitors from venomous animals. Fundamental features that were emphasized in training ClanTox include cysteines and their spacing along the sequences. Among the 83,000 proteins derived from Cnidaria representatives, we found 170 candidates that fulfill the properties of toxin-like-proteins, the vast majority of which were previously unrecognized as toxins. An additional 394 short proteins exhibit characteristics of toxin-like proteins at a moderate degree of confidence. Remarkably, only 11% of the predicted toxin-like proteins were previously classified as toxins. Based on our prediction methodology and manual annotation, we inferred functions for over 400 of these proteins. Such functions include protease inhibitors, membrane pore formation, ion channel blockers and metal binding proteins. Many of the proteins belong to small families of paralogs. We conclude that the evolutionary expansion of toxin-like proteins in Cnidaria contributes to their fitness in the complex environment of the aquatic ecosystem. PMID:23202321

In vitro reconstitution of the Clostridium botulinum type D progenitor toxin.

PubMed

Kouguchi, Hirokazu; Watanabe, Toshihiro; Sagane, Yoshimasa; Sunagawa, Hiroyuki; Ohyama, Tohru

2002-01-25

Clostridium botulinum type D strain 4947 produces two different sizes of progenitor toxins (M and L) as intact forms without proteolytic processing. The M toxin is composed of neurotoxin (NT) and nontoxic-nonhemagglutinin (NTNHA), whereas the L toxin is composed of the M toxin and hemagglutinin (HA) subcomponents (HA-70, HA-17, and HA-33). The HA-70 subcomponent and the HA-33/17 complex were isolated from the L toxin to near homogeneity by chromatography in the presence of denaturing agents. We were able to demonstrate, for the first time, in vitro reconstitution of the L toxin formed by mixing purified M toxin, HA-70, and HA-33/17. The properties of reconstituted and native L toxins are indistinguishable with respect to their gel filtration profiles, native-PAGE profiles, hemagglutination activity, binding activity to erythrocytes, and oral toxicity to mice. M toxin, which contained nicked NTNHA prepared by treatment with trypsin, could no longer be reconstituted to the L toxin with HA subcomponents, whereas the L toxin treated with proteases was not degraded into M toxin and HA subcomponents. We conclude that the M toxin forms first by assembly of NT with NTNHA and is subsequently converted to the L toxin by assembly with HA-70 and HA-33/17.

Botulinum toxin in pain treatment.

PubMed

Colhado, Orlando Carlos Gomes; Boeing, Marcelo; Ortega, Luciano Bornia

2009-01-01

Botulinum toxin (BTX) is one of the most potent bacterial toxins known and its effectiveness in the treatment of some pain syndromes is well known. However, the efficacy of some of its indications is still in the process of being confirmed. The objective of this study was to review the history, pharmacological properties, and clinical applications of BTX in the treatment of pain of different origins. Botulinum toxin is produced by fermentation of Clostridium botulinum, a Gram-positive, anaerobic bacterium. Commercially, BTX comes in two presentations, types A and B. Botulinum toxin, a neurotoxin with high affinity for cholinergic synapses, blocks the release of acetylcholine by nerve endings without interfering with neuronal conduction of electrical signals or synthesis and storage of acetylcholine. It has been proven that BTX can selectively weaken painful muscles, interrupting the spasm-pain cycle. Several studies have demonstrated the efficacy and safety of BTX-A in the treatment of tension headaches, migraines, chronic lumbar pain, and myofascial pain. Botulinum toxin type A is well tolerated in the treatment of chronic pain disorders in which pharmacotherapy regimens can cause side effects. The reduction in the consumption of analgesics and length of action of 3 to 4 months per dose represent other advantages of its use. However, further studies are necessary to establish the efficacy of BTX-A in chronic pain disorders and its exact mechanism of action, as well as its potential in multifactorial treatments.

Botulinum Toxin for Rhinitis.

PubMed

Ozcan, Cengiz; Ismi, Onur

2016-08-01

Rhinitis is a common clinical entity. Besides nasal obstruction, itching, and sneezing, one of the most important symptoms of rhinitis is nasal hypersecretion produced by nasal glands and exudate from the nasal vascular bed. Allergic rhinitis is an IgE-mediated inflammatory reaction of nasal mucosa after exposure to environmental allergens. Idiopathic rhinitis describes rhinitis symptoms that occur after non-allergic, noninfectious irritants. Specific allergen avoidance, topical nasal decongestants, nasal corticosteroids, immunotherapy, and sinonasal surgery are the main treatment options. Because the current treatment modalities are not enough for reducing rhinorrhea in some patients, novel treatment options are required to solve this problem. Botulinum toxin is an exotoxin generated by Clostridium botulinum. It disturbs the signal transmission at the neuromuscular and neuroglandular junction by inhibiting the acetylcholine release from the presynaptic nerve terminal. It has been widely used in neuromuscular, hypersecretory, and autonomic nerve system disorders. There have been a lot of published articles concerning the effect of this toxin on rhinitis symptoms. Based on the results of these reports, intranasal botulinum toxin A administration appears to be a safe and effective treatment method for decreasing rhinitis symptoms in rhinitis patients with a long-lasting effect. Botulinum toxin type A will be a good treatment option for the chronic rhinitis patients who are resistant to other treatment methods.

The role of toxins in Clostridium difficile infection.

PubMed

Chandrasekaran, Ramyavardhanee; Lacy, D Borden

2017-11-01

Clostridium difficile is a bacterial pathogen that is the leading cause of nosocomial antibiotic-associated diarrhea and pseudomembranous colitis worldwide. The incidence, severity, mortality and healthcare costs associated with C. difficile infection (CDI) are rising, making C. difficile a major threat to public health. Traditional treatments for CDI involve use of antibiotics such as metronidazole and vancomycin, but disease recurrence occurs in about 30% of patients, highlighting the need for new therapies. The pathogenesis of C. difficile is primarily mediated by the actions of two large clostridial glucosylating toxins, toxin A (TcdA) and toxin B (TcdB). Some strains produce a third toxin, the binary toxin C. difficile transferase, which can also contribute to C. difficile virulence and disease. These toxins act on the colonic epithelium and immune cells and induce a complex cascade of cellular events that result in fluid secretion, inflammation and tissue damage, which are the hallmark features of the disease. In this review, we summarize our current understanding of the structure and mechanism of action of the C. difficile toxins and their role in disease. Published by Oxford University Press on behalf of FEMS 2017.

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.

Temperature Effects Explain Continental Scale Distribution of Cyanobacterial Toxins

PubMed Central

Mantzouki, Evanthia; Fastner, Jutta; de Senerpont Domis, Lisette; Wilk-Woźniak, Elżbieta; Koreivienė, Judita; Verstijnen, Yvon; Krztoń, Wojciech; Walusiak, Edward; Karosienė, Jūratė; Kasperovičienė, Jūratė; Savadova, Ksenija; Vitonytė, Irma; Budzyńska, Agnieszka; Szeląg-Wasielewska, Elżbieta; Domek, Piotr; Messyasz, Beata; Pełechata, Aleksandra; Pełechaty, Mariusz; Kokocinski, Mikolaj; García-Murcia, Ana; Real, Monserrat; Romans, Elvira; Noguero-Ribes, Jordi; Duque, David Parreño; Karakaya, Nusret; Häggqvist, Kerstin; Beklioğlu, Meryem; Filiz, Nur; Iskin, Uğur; Bezirci, Gizem; Tavşanoğlu, Ülkü Nihan; Panou, Manthos; Fakioglu, Özden; Avagianos, Christos; Çelik, Kemal; Yilmaz, Mete; Marcé, Rafael; Buck, Moritz; Colom-Montero, William; Mustonen, Kristiina; Pierson, Don; Yang, Yang; Raposeiro, Pedro M.; Antoniou, Maria G.; Tsiarta, Nikoletta; McCarthy, Valerie; Perello, Victor C.; Feldmann, Tõnu; Panksep, Kristel; Tuvikene, Lea; Gagala, Ilona; Çınar, Şakir; Çapkın, Kadir; Yağcı, Abdulkadir; Cesur, Mehmet; Bilgin, Fuat; Bulut, Cafer; Uysal, Rahmi; Boscaini, Adriano; Cerasino, Leonardo; Richardson, Jessica; Visser, Petra M.; Verspagen, Jolanda M. H.; Karan, Tünay; Ochocka, Agnieszka; Pasztaleniec, Agnieszka; Köker, Latife; Albay, Meriç; Maronić, Dubravka Špoljarić; Stević, Filip; Pfeiffer, Tanja Žuna; Fonvielle, Jeremy; Rothhaupt, Karl-Otto; Hansson, Lars-Anders; Bláha, Luděk; Geriš, Rodan; Fránková, Markéta; Koçer, Mehmet Ali Turan; Alp, Mehmet Tahir; Remec-Rekar, Spela; Elersek, Tina; Hiskia, Anastasia; Haande, Sigrid; Skjelbred, Birger; Madrecka, Beata; Nemova, Hana; Drastichova, Iveta; Chomova, Lucia; Edwards, Christine; Sevindik, Tuğba Ongun; Tunca, Hatice; Önem, Burçin; Aleksovski, Boris; Krstić, Svetislav; Vucelić, Itana Bokan; Nawrocka, Lidia; Salmi, Pauliina; Machado-Vieira, Danielle; de Oliveira, Alinne Gurjão; Delgado-Martín, Jordi; García, David; Cereijo, Jose Luís; Trapote, Mari Carmen; Obrador, Biel; Grabowska, Magdalena; Chmura, Damian; Úbeda, Bárbara; Warming, Trine Perlt; Kobos, Justyna; Mazur-Marzec, Hanna; Arvola, Lauri; Alcaraz-Párraga, Pablo; Toporowska, Magdalena; Pawlik-Skowronska, Barbara; Niedźwiecki, Michał; Pęczuła, Wojciech; Moreno-Ostos, Enrique; Blanco, José María; Rodríguez, Valeriano; Montes-Pérez, Jorge Juan; Palomino, Roberto L.; Rodríguez-Pérez, Estela; Carballeira, Rafael; Picazo, Antonio; Santamans, Anna C.; Ferriol, Carmen; Romo, Susana; Dunalska, Julita; Sieńska, Justyna; Szymański, Daniel; Kostrzewska-Szlakowska, Iwona; Jasser, Iwona; Žutinić, Petar; Udovič, Marija Gligora; Plenković-Moraj, Anđelka; Frąk, Magdalena; Bańkowska-Sobczak, Agnieszka; Wasilewicz, Michał; Özkan, Korhan; Kangro, Kersti; Ibelings, Bas W.

2018-01-01

Insight into how environmental change determines the production and distribution of cyanobacterial toxins is necessary for risk assessment. Management guidelines currently focus on hepatotoxins (microcystins). Increasing attention is given to other classes, such as neurotoxins (e.g., anatoxin-a) and cytotoxins (e.g., cylindrospermopsin) due to their potency. Most studies examine the relationship between individual toxin variants and environmental factors, such as nutrients, temperature and light. In summer 2015, we collected samples across Europe to investigate the effect of nutrient and temperature gradients on the variability of toxin production at a continental scale. Direct and indirect effects of temperature were the main drivers of the spatial distribution in the toxins produced by the cyanobacterial community, the toxin concentrations and toxin quota. Generalized linear models showed that a Toxin Diversity Index (TDI) increased with latitude, while it decreased with water stability. Increases in TDI were explained through a significant increase in toxin variants such as MC-YR, anatoxin and cylindrospermopsin, accompanied by a decreasing presence of MC-LR. While global warming continues, the direct and indirect effects of increased lake temperatures will drive changes in the distribution of cyanobacterial toxins in Europe, potentially promoting selection of a few highly toxic species or strains. PMID:29652856

Temperature Effects Explain Continental Scale Distribution of Cyanobacterial Toxins.

PubMed

Mantzouki, Evanthia; Lürling, Miquel; Fastner, Jutta; de Senerpont Domis, Lisette; Wilk-Woźniak, Elżbieta; Koreivienė, Judita; Seelen, Laura; Teurlincx, Sven; Verstijnen, Yvon; Krztoń, Wojciech; Walusiak, Edward; Karosienė, Jūratė; Kasperovičienė, Jūratė; Savadova, Ksenija; Vitonytė, Irma; Cillero-Castro, Carmen; Budzyńska, Agnieszka; Goldyn, Ryszard; Kozak, Anna; Rosińska, Joanna; Szeląg-Wasielewska, Elżbieta; Domek, Piotr; Jakubowska-Krepska, Natalia; Kwasizur, Kinga; Messyasz, Beata; Pełechaty, Aleksandra; Pełechaty, Mariusz; Kokocinski, Mikolaj; García-Murcia, Ana; Real, Monserrat; Romans, Elvira; Noguero-Ribes, Jordi; Duque, David Parreño; Fernández-Morán, Elísabeth; Karakaya, Nusret; Häggqvist, Kerstin; Demir, Nilsun; Beklioğlu, Meryem; Filiz, Nur; Levi, Eti E.; Iskin, Uğur; Bezirci, Gizem; Tavşanoğlu, Ülkü Nihan; Özhan, Koray; Gkelis, Spyros; Panou, Manthos; Fakioglu, Özden; Avagianos, Christos; Kaloudis, Triantafyllos; Çelik, Kemal; Yilmaz, Mete; Marcé, Rafael; Catalán, Nuria; Bravo, Andrea G.; Buck, Moritz; Colom-Montero, William; Mustonen, Kristiina; Pierson, Don; Yang, Yang; Raposeiro, Pedro M.; Gonçalves, Vítor; Antoniou, Maria G.; Tsiarta, Nikoletta; McCarthy, Valerie; Perello, Victor C.; Feldmann, Tõnu; Laas, Alo; Panksep, Kristel; Tuvikene, Lea; Gagala, Ilona; Mankiewicz-Boczek, Joana; Yağcı, Meral Apaydın; Çınar, Şakir; Çapkın, Kadir; Yağcı, Abdulkadir; Cesur, Mehmet; Bilgin, Fuat; Bulut, Cafer; Uysal, Rahmi; Obertegger, Ulrike; Boscaini, Adriano; Flaim, Giovanna; Salmaso, Nico; Cerasino, Leonardo; Richardson, Jessica; Visser, Petra M.; Verspagen, Jolanda M. H.; Karan, Tünay; Soylu, Elif Neyran; Maraşlıoğlu, Faruk; Napiórkowska-Krzebietke, Agnieszka; Ochocka, Agnieszka; Pasztaleniec, Agnieszka; Antão-Geraldes, Ana M.; Vasconcelos, Vitor; Morais, João; Vale, Micaela; Köker, Latife; Akçaalan, Reyhan; Albay, Meriç; Špoljarić Maronić, Dubravka; Stević, Filip; Žuna Pfeiffer, Tanja; Fonvielle, Jeremy; Straile, Dietmar; Rothhaupt, Karl-Otto; Hansson, Lars-Anders; Urrutia-Cordero, Pablo; Bláha, Luděk; Geriš, Rodan; Fránková, Markéta; Koçer, Mehmet Ali Turan; Alp, Mehmet Tahir; Remec-Rekar, Spela; Elersek, Tina; Triantis, Theodoros; Zervou, Sevasti-Kiriaki; Hiskia, Anastasia; Haande, Sigrid; Skjelbred, Birger; Madrecka, Beata; Nemova, Hana; Drastichova, Iveta; Chomova, Lucia; Edwards, Christine; Sevindik, Tuğba Ongun; Tunca, Hatice; Önem, Burçin; Aleksovski, Boris; Krstić, Svetislav; Vucelić, Itana Bokan; Nawrocka, Lidia; Salmi, Pauliina; Machado-Vieira, Danielle; de Oliveira, Alinne Gurjão; Delgado-Martín, Jordi; García, David; Cereijo, Jose Luís; Gomà, Joan; Trapote, Mari Carmen; Vegas-Vilarrúbia, Teresa; Obrador, Biel; Grabowska, Magdalena; Karpowicz, Maciej; Chmura, Damian; Úbeda, Bárbara; Gálvez, José Ángel; Özen, Arda; Christoffersen, Kirsten Seestern; Warming, Trine Perlt; Kobos, Justyna; Mazur-Marzec, Hanna; Pérez-Martínez, Carmen; Ramos-Rodríguez, Eloísa; Arvola, Lauri; Alcaraz-Párraga, Pablo; Toporowska, Magdalena; Pawlik-Skowronska, Barbara; Niedźwiecki, Michał; Pęczuła, Wojciech; Leira, Manel; Hernández, Armand; Moreno-Ostos, Enrique; Blanco, José María; Rodríguez, Valeriano; Montes-Pérez, Jorge Juan; Palomino, Roberto L.; Rodríguez-Pérez, Estela; Carballeira, Rafael; Camacho, Antonio; Picazo, Antonio; Rochera, Carlos; Santamans, Anna C.; Ferriol, Carmen; Romo, Susana; Soria, Juan Miguel; Dunalska, Julita; Sieńska, Justyna; Szymański, Daniel; Kruk, Marek; Kostrzewska-Szlakowska, Iwona; Jasser, Iwona; Žutinić, Petar; Gligora Udovič, Marija; Plenković-Moraj, Anđelka; Frąk, Magdalena; Bańkowska-Sobczak, Agnieszka; Wasilewicz, Michał; Özkan, Korhan; Maliaka, Valentini; Kangro, Kersti; Grossart, Hans-Peter; Paerl, Hans W.; Carey, Cayelan C.; Ibelings, Bas W.

2018-04-13

Insight into how environmental change determines the production and distribution of cyanobacterial toxins is necessary for risk assessment. Management guidelines currently focus on hepatotoxins (microcystins). Increasing attention is given to other classes, such as neurotoxins (e.g., anatoxin-a) and cytotoxins (e.g., cylindrospermopsin) due to their potency. Most studies examine the relationship between individual toxin variants and environmental factors, such as nutrients, temperature and light. In summer 2015, we collected samples across Europe to investigate the effect of nutrient and temperature gradients on the variability of toxin production at a continental scale. Direct and indirect effects of temperature were the main drivers of the spatial distribution in the toxins produced by the cyanobacterial community, the toxin concentrations and toxin quota. Generalized linear models showed that a Toxin Diversity Index (TDI) increased with latitude, while it decreased with water stability. Increases in TDI were explained through a significant increase in toxin variants such as MC-YR, anatoxin and cylindrospermopsin, accompanied by a decreasing presence of MC-LR. While global warming continues, the direct and indirect effects of increased lake temperatures will drive changes in the distribution of cyanobacterial toxins in Europe, potentially promoting selection of a few highly toxic species or strains.

Hemorrhagic Shock and Surgical Stress Alter Distribution of Labile Zinc within High and Low Molecular Weight Plasma Fractions

PubMed Central

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

2012-01-01

Zinc ions (Zn2+) are essential for tissue repair following injury or stress. We hypothesize that during such stresses Zn2+ is redistributed to labile pools in plasma components. Here we tested this hypothesis utilizing a novel assay to monitor labile Zn2+ in plasma in hemorrhagic shock. Adult rats in the Shock (S) group underwent hemorrhage and resuscitation. Blood samples were drawn at baseline, 1 hr, 4 hrs and 24 hrs. The Surgical Control (SC) group was anesthetized and instrumented, but not bled. Albumin, total Zn2+, and labile Zn2+ levels were assayed in plasma. Binding capacity for Zn2+ was assessed in high (HMW) and low (LMW) molecular weight pools. Significant decreases in total Zn2+ were observed by 24 hrs, in both S and SC groups. Albumin levels were significantly reduced in the S group at 1 hr and 4 hr but restored at 24 hrs; significant changes were not observed in other groups. In whole plasma, labile Zn2+ levels were stable initially in the S and SC groups, but declined at 24 hrs. In the HMW pool, marked and significant impairment of binding was noted throughout all time periods following the shock period in the S group. Such changes were observed in the SC group of less intensity and duration. These experiments suggest that Shock alters affinity of plasma proteins for Zn2+, promoting delivery to peripheral tissues during periods of increased Zn2+ utilization. PMID:22744307

Hemorrhagic shock and surgical stress alter distribution of labile zinc within high- and low-molecular-weight plasma fractions.

PubMed

Kelly, Edward; Mathew, Jeff; Kohler, Jonathan E; Blass, Amy L; Soybel, And David I

2012-08-01

Zinc ions (Zn) are essential for tissue repair following injury or stress. We hypothesize that during such stresses Zn is redistributed to labile pools in plasma components. Here we tested this hypothesis using a novel assay to monitor labile Zn in plasma in hemorrhagic shock. Adult rats in the shock group (S group) underwent hemorrhage and resuscitation. Blood samples were drawn at baseline and at 1, 4, and 24 h. The surgical control group (SC group) was anesthetized and instrumented, but not bled. Albumin, total Zn, and labile Zn levels were assayed in plasma. Binding capacity for Zn was assessed in high- and low-molecular-weight pools. Significant decreases in total Zn were observed by 24 h, in both S and SC groups. Albumin levels were significantly reduced in the S group at 1 and 4 h but restored at 24 h; significant changes were not observed in other groups. In whole plasma, labile Zn levels were stable initially in the S and SC groups, but declined at 24 h. In the high-molecular-weight pool, marked and significant impairment of binding was noted throughout all time periods following the shock period in the S group. Such changes were observed in the SC group of less intensity and duration. These experiments suggest that shock alters affinity of plasma proteins for Zn, promoting delivery to peripheral tissues during periods of increased Zn utilization.

Dinoflagellate Toxins Responsible for Ciguatera Food Poisoning

DTIC Science & Technology

1987-12-10

the occurrence and importance of secondary toxins (12, 13, 14, 15, 16 and 17). Hutner and McLaughlin (18) suggested that the zooxanthellae ...argued that zooxanthellae were unlikely prospects because very few fishes eat coral and saxitoxin (STX = a paralytic shellfish poison which originates...of the toxins was not based on tests of zooxanthellae species but rather on the assumption that all dinoflagellate toxins would be expected to be

Diphtheria toxin translocation across cellular membranes is regulated by sphingolipids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Spilsberg, Bjorn; Hanada, Kentaro; Sandvig, Kirsten

2005-04-08

Diphtheria toxin is translocated across cellular membranes when receptor-bound toxin is exposed to low pH. To study the role of sphingolipids for toxin translocation, both a mutant cell line lacking the first enzyme in de novo sphingolipid synthesis, serine palmitoyltransferase, and a specific inhibitor of the same enzyme, myriocin, were used. The serine palmitoyltransferase-deficient cell line (LY-B) was found to be 10-15 times more sensitive to diphtheria toxin than the genetically complemented cell line (LY-B/cLCB1) and the wild-type cell line (CHO-K1), both when toxin translocation directly across the plasma membrane was induced by exposing cells with surface-bound toxin to lowmore » pH, and when the toxin followed its normal route via acidified endosomes into the cytosol. Toxin binding was similar in these three cell lines. Furthermore, inhibition of serine palmitoyltransferase activity by addition of myriocin sensitized the two control cell lines (LY-B/cLCB1 and CHO-K1) to diphtheria toxin, whereas, as expected, no effect was observed in cells lacking serine palmitoyltransferase (LY-B). In conclusion, diphtheria toxin translocation is facilitated by depletion of membrane sphingolipids.« less

Formation and Control of Cyanobacterial Toxins

EPA Science Inventory

This presentation will cover the formation of harmful algal blooms and the control of their toxins. Data will be presented from current ORD projects on the treatment of cyanobacterial toxins through drinking water treatment facilities. The results will demonstrate that current c...

Natural toxins of plant origin (phytotoxins)

USDA-ARS?s Scientific Manuscript database

Over 100,000 secondary compounds have been identified in plants including alkaloids, glycosides, proteins, polypeptides, amines and non-protein amino acids, organic acids, alcohols, polyacetylenes, resinous toxins and mineral toxins. For thousands of years man has used some of these compounds as fl...

The life history of a botulinum toxin molecule.

PubMed

Simpson, Lance

2013-06-01

There is an emerging literature describing the absorption, distribution, metabolism and elimination of botulinum toxin. This work reveals that the toxin can be absorbed by both the oral and inhalation routes. The primary mechanism for absorption is binding and transport across epithelial cells. Toxin that enters the body undergoes a distribution phase, which is quite short, and an elimination phase, which is comparatively long. During the distribution phase, botulinum toxin migrates to the peri-neuronal microcompartment in the vicinity of vulnerable cells, such as cholinergic nerve endings. Only these cells have the ability to selectively accumulate the molecule. When the toxin moves from the cell membrane to the cell interior, it undergoes programmed death. This is coincident with release of the catalytically active light chain that paralyzes transmission. Intraneuronal metabolism of light chain is via the ubiquitination-proteasome pathway. Systemic metabolism and elimination is assumed to be via the liver. The analysis of absorption, distribution, metabolism and elimination of the toxin helps to create a life history of the molecule in the body. This has many benefits, including: a) clarifying the mechanisms that underlie the disease botulism, b) providing insights for development of medical countermeasures against the toxin, and c) helping to explain the meaning of a lethal dose of toxin. It is likely that work intended to enhance understanding of the fate of botulinum toxin in the body will intensify. These efforts will include new and powerful analytic tools, such as single molecule-single cell analyses in vitro and real time, 3-dimensional pharmacokinetic studies in vivo. Copyright © 2013 Elsevier Ltd. All rights reserved.

Nanoparticulated heat-stable (STa) and heat-labile B subunit (LTB) recombinant toxin improves vaccine protection against enterotoxigenic Escherichia coli challenge in mouse.

PubMed

Deng, Guangcun; Zeng, Jin; Jian, Minjie; Liu, Wenmiao; Zhang, Zhong; Liu, Xiaoming; Wang, Yujiong

2013-02-01

Enterotoxigenic Escherichia coli (ETEC) remains a major cause of diarrheic disease in developing areas, for which there is no effective vaccine available. In this study, we genetically engineered a recombinant heat-stable enterotoxin (STa) coupled to the subunit B of heat-labile enterotoxin (LTB). This fusion protein, STa-LTB, possesses a single amino acid substitution at position 14 of STa. Our data demonstrates that the enterotoxicity of STa in STa-LTB was dramatically reduced. A gelatin nanovaccine candidate was prepared using the purified STa-LTB fusion protein characterized with an entrapment efficiency of 84.88 ± 6.37% and smooth spheres size ranges of 80-200 nm. Antigen-specific antibody responses against STa-LTB and STa in the sera and the intestinal mucus respectively were used to test the immunogenicity of the nanovaccine. This vaccine was further screened in mice by its ability to elicit neutralizing antibodies against STa and protect animals from the challenge with ETEC in mice. The STa-LTB nanoparticles delivered demonstrated a capacity to induce significantly higher and long-lasting antibody responses and increased immune protection against ETEC challenge relative to the control STa-LTB vaccine absorbed in conventional aluminum hydrate salt (p < 0.01). These results warrant the further studies of the development of a novel nanoparticulate vaccine as a broad-spectrum vaccine against ETEC infection. Copyright © 2012 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Lack of activity of 15-epi-lipoxin A₄ on FPR2/ALX and CysLT1 receptors in interleukin-8-driven human neutrophil function.

PubMed

Planagumà, A; Domenech, T; Jover, I; Ramos, I; Sentellas, S; Malhotra, R; Miralpeix, M

2013-08-01

Neutrophil recruitment and survival are important control points in the development and resolution of inflammatory processes. 15-epi-lipoxin (LX)A interaction with formyl peptide receptor 2 (FPR2)/ALX receptor is suggested to enhance anti-inflammatory neutrophil functions and mediate resolution of airway inflammation. However, it has been reported that 15-epi-LXA₄ analogues can also bind to cysteinyl leukotriene receptor 1 (CysLT1) and that the CysLT1 antagonist MK-571 binds to FPR2/ALX, so cross-reactivity between FPR2/ALX and CysLT1 ligands cannot be discarded. It is not well established whether the resolution properties reported for 15-epi-LXA4 are mediated through FPR2/ALX, or if other receptors such as CysLT1 may also be involved. Evaluation of specific FPR2/ALX ligands and CysLT1 antagonists in functional biochemical and cellular assays were performed to establish a role for both receptors in 15-epi-LXA₄-mediated signalling and function. In our study, a FPR2/ALX synthetic peptide (WKYMVm) and a small molecule FPR2/ALX agonist (compound 43) induced FPR2/ALX-mediated signalling, enhancing guanosine triphosphate-gamma (GTPγ) binding and decreasing cyclic adenosine monophosphate (cAMP) levels, whereas 15-epi-LXA₄ was inactive. Furthermore, 15-epi-LXA4 showed neither binding affinity nor signalling towards CysLT1. In neutrophils, 15-epi-LXA₄ showed a moderate reduction of interleukin (IL)-8-mediated neutrophil chemotaxis but no effect on neutrophil survival was observed. In addition, CysLT1 antagonists were inactive in FPR2/ALX signalling or neutrophil assays. In conclusion, 15-epi-LXA₄ is not a functional agonist or an antagonist of FPR2/ALX or CysLT1, shows no effect on IL-8-induced neutrophil survival and produces only moderate inhibition in IL-8-mediated neutrophil migration. Our data do not support an anti-inflammatory role of 15-epi-LXA₄- FPR2/ALX interaction in IL-8-induced neutrophil inflammation. © 2013 British Society for Immunology.

The ng_ζ1 toxin of the gonococcal epsilon/zeta toxin/antitoxin system drains precursors for cell wall synthesis.

PubMed

Rocker, Andrea; Peschke, Madeleine; Kittilä, Tiia; Sakson, Roman; Brieke, Clara; Meinhart, Anton

2018-04-27

Bacterial toxin-antitoxin complexes are emerging as key players modulating bacterial physiology as activation of toxins induces stasis or programmed cell death by interference with vital cellular processes. Zeta toxins, which are prevalent in many bacterial genomes, were shown to interfere with cell wall formation by perturbing peptidoglycan synthesis in Gram-positive bacteria. Here, we characterize the epsilon/zeta toxin-antitoxin (TA) homologue from the Gram-negative pathogen Neisseria gonorrhoeae termed ng_ɛ1 / ng_ζ1. Contrary to previously studied streptococcal epsilon/zeta TA systems, ng_ɛ1 has an epsilon-unrelated fold and ng_ζ1 displays broader substrate specificity and phosphorylates multiple UDP-activated sugars that are precursors of peptidoglycan and lipopolysaccharide synthesis. Moreover, the phosphorylation site is different from the streptococcal zeta toxins, resulting in a different interference with cell wall synthesis. This difference most likely reflects adaptation to the individual cell wall composition of Gram-negative and Gram-positive organisms but also the distinct involvement of cell wall components in virulence.

Feasibility of labile Zn phytoextraction using enhanced tobacco and sunflower: results of five- and one-year field-scale experiments in Switzerland.

PubMed

Herzig, Rolf; Nehnevajova, Erika; Pfistner, Charlotte; Schwitzguebel, Jean-Paul; Ricci, Arturo; Keller, Charles

2014-01-01

Phytoextraction with somaclonal variants of tobacco and sunflower mutant lines (non-GMs) with enhanced metal uptake and tolerance can be a sustainable alternative to conventional destructive decontamination methods, especially for stripping bioavailable zinc excess in topsoil. The overall results of a 5-year time series experiment at field scale in north-eastern Switzerland confirm that the labile Zn pool in soil can be lowered by 45-70%, whereas subplots without phytoextraction treatment maintained labile Zn concentrations. In 2011, the phytoextraction experiment site was enlarged by a factor of 3, and the labile 0.1 M NaNO3 extractable Zn concentration in the soil was reduced up to 58% one period after harvest. A Mass Balance Analysis confirmed soil Zn decontamination in line with plant Zn uptake. The plants partially take Zn from the non-labile pool of the totaL The sustainability of Zn phytoextraction in subplots that no longer exceed the Swiss trigger value is now assessed over time. In contrary to the phytoextraction of total soil Zn which needs a long cleaning up time, the bioavailable Zn stripping is feasible within a few years period.

Lability of Secondary Organic Particulate Matter

DOE PAGES

Liu, Pengfei; Li, Yong Jie; Wang, Yan; ...

2016-10-24

Accurate simulations of the consenctrations of atmospheric organic particulate matter (PM) are needed for predicting energy flow in the Earth’s climate system. In the past, simulations of organic PM widely assume equilibrium partitioning of semivolatile organic compounds (SVOCs) between the PM and surrounding vapor. Herein, we test this assumption by measuring evaporation rates and associated vapor mass concentration of organic films representative of atmospheric PM. For films representing anthropogenic PM, evaporation rates and vapor mass concentrations increased above a threshold relative humidity (RH), indicating equilibrium partitioning above a transition RH but not below. In contrast for films representing biogenic PM,more » no threshold was observed, indicating equilibrium partitioning at all RHs. The results suggest that the mass lability of atmospheric organic PM can differ in consequential ways among Earth’s natural biomes, polluted regions, and regions of land-use change, and these differences need to be considered when simulating atmospheric organic PM.« less

Risk Assessment of Shellfish Toxins

PubMed Central

Munday, Rex; Reeve, John

2013-01-01

Complex secondary metabolites, some of which are highly toxic to mammals, are produced by many marine organisms. Some of these organisms are important food sources for marine animals and, when ingested, the toxins that they produce may be absorbed and stored in the tissues of the predators, which then become toxic to animals higher up the food chain. This is a particular problem with shellfish, and many cases of poisoning are reported in shellfish consumers each year. At present, there is no practicable means of preventing uptake of the toxins by shellfish or of removing them after harvesting. Assessment of the risk posed by such toxins is therefore required in order to determine levels that are unlikely to cause adverse effects in humans and to permit the establishment of regulatory limits in shellfish for human consumption. In the present review, the basic principles of risk assessment are described, and the progress made toward robust risk assessment of seafood toxins is discussed. While good progress has been made, it is clear that further toxicological studies are required before this goal is fully achieved. PMID:24226039

CD44 Promotes intoxication by the clostridial iota-family toxins.

PubMed

Wigelsworth, Darran J; Ruthel, Gordon; Schnell, Leonie; Herrlich, Peter; Blonder, Josip; Veenstra, Timothy D; Carman, Robert J; Wilkins, Tracy D; Van Nhieu, Guy Tran; Pauillac, Serge; Gibert, Maryse; Sauvonnet, Nathalie; Stiles, Bradley G; Popoff, Michel R; Barth, Holger

2012-01-01

Various pathogenic clostridia produce binary protein toxins associated with enteric diseases of humans and animals. Separate binding/translocation (B) components bind to a protein receptor on the cell surface, assemble with enzymatic (A) component(s), and mediate endocytosis of the toxin complex. Ultimately there is translocation of A component(s) from acidified endosomes into the cytosol, leading to destruction of the actin cytoskeleton. Our results revealed that CD44, a multifunctional surface protein of mammalian cells, facilitates intoxication by the iota family of clostridial binary toxins. Specific antibody against CD44 inhibited cytotoxicity of the prototypical Clostridium perfringens iota toxin. Versus CD44(+) melanoma cells, those lacking CD44 bound less toxin and were dose-dependently resistant to C. perfringens iota, as well as Clostridium difficile and Clostridium spiroforme iota-like, toxins. Purified CD44 specifically interacted in vitro with iota and iota-like, but not related Clostridium botulinum C2, toxins. Furthermore, CD44 knockout mice were resistant to iota toxin lethality. Collective data reveal an important role for CD44 during intoxication by a family of clostridial binary toxins.

CD44 Promotes Intoxication by the Clostridial Iota-Family Toxins

PubMed Central

Wigelsworth, Darran J.; Ruthel, Gordon; Schnell, Leonie; Herrlich, Peter; Blonder, Josip; Veenstra, Timothy D.; Carman, Robert J.; Wilkins, Tracy D.; Van Nhieu, Guy Tran; Pauillac, Serge; Gibert, Maryse; Sauvonnet, Nathalie; Stiles, Bradley G.; Popoff, Michel R.; Barth, Holger

2012-01-01

Various pathogenic clostridia produce binary protein toxins associated with enteric diseases of humans and animals. Separate binding/translocation (B) components bind to a protein receptor on the cell surface, assemble with enzymatic (A) component(s), and mediate endocytosis of the toxin complex. Ultimately there is translocation of A component(s) from acidified endosomes into the cytosol, leading to destruction of the actin cytoskeleton. Our results revealed that CD44, a multifunctional surface protein of mammalian cells, facilitates intoxication by the iota family of clostridial binary toxins. Specific antibody against CD44 inhibited cytotoxicity of the prototypical Clostridium perfringens iota toxin. Versus CD44+ melanoma cells, those lacking CD44 bound less toxin and were dose-dependently resistant to C. perfringens iota, as well as Clostridium difficile and Clostridium spiroforme iota-like, toxins. Purified CD44 specifically interacted in vitro with iota and iota-like, but not related Clostridium botulinum C2, toxins. Furthermore, CD44 knockout mice were resistant to iota toxin lethality. Collective data reveal an important role for CD44 during intoxication by a family of clostridial binary toxins. PMID:23236484

Structural Insights into Clostridium perfringens Delta Toxin Pore Formation

PubMed Central

Huyet, Jessica; Naylor, Claire E.; Savva, Christos G.; Gibert, Maryse; Popoff, Michel R.; Basak, Ajit K.

2013-01-01

Clostridium perfringens Delta toxin is one of the three hemolysin-like proteins produced by C. perfringens type C and possibly type B strains. One of the others, NetB, has been shown to be the major cause of Avian Nectrotic Enteritis, which following the reduction in use of antibiotics as growth promoters, has become an emerging disease of industrial poultry. Delta toxin itself is cytotoxic to the wide range of human and animal macrophages and platelets that present GM2 ganglioside on their membranes. It has sequence similarity with Staphylococcus aureus β-pore forming toxins and is expected to heptamerize and form pores in the lipid bilayer of host cell membranes. Nevertheless, its exact mode of action remains undetermined. Here we report the 2.4 Å crystal structure of monomeric Delta toxin. The superposition of this structure with the structure of the phospholipid-bound F component of S. aureus leucocidin (LukF) revealed that the glycerol molecules bound to Delta toxin and the phospholipids in LukF are accommodated in the same hydrophobic clefts, corresponding to where the toxin is expected to latch onto the membrane, though the binding sites show significant differences. From structure-based sequence alignment with the known structure of staphylococcal α-hemolysin, a model of the Delta toxin pore form has been built. Using electron microscopy, we have validated our model and characterized the Delta toxin pore on liposomes. These results highlight both similarities and differences in the mechanism of Delta toxin (and by extension NetB) cytotoxicity from that of the staphylococcal pore-forming toxins. PMID:23805259

[Staphylococcal toxin of toxic shock syndrome].

PubMed

Fluer, F S

2007-01-01

Literature data on toxic shock syndrome staphylococcal toxin (TSST-1) are summarized; properties of Staphylococcus aureus strains producing TSST-1, nutrient media, and factors influencing on production of TSST-1 are reviewed. Physical and chemical properties of the toxin, its molecular characteristics, genetic regulation of its production, mechanism of action, and diseases which it causes are also discussed. Clinical and histologic signs of toxic shock syndrome (TSS), its diagnostic criteria, susceptibility of people to TSS, antigenic and serologic properties of the toxin, epidemiology of the infection caused by TSST-1-producing strains of staphylococci, methods of TSST-1 extraction and identification are described.

Assessing SOC labile fractions through respiration test, density-size fractionation and thermal analysis - A comparison of methods

NASA Astrophysics Data System (ADS)

Soucemarianadin, Laure; Cécillon, Lauric; Chenu, Claire; Baudin, François; Nicolas, Manuel; Savignac, Florence; Barré, Pierre

2017-04-01

Soil organic matter (SOM) is the biggest terrestrial carbon reservoir, storing 3 to 4 times more carbon than the atmosphere. However, despite its major importance for climate regulation SOM dynamics remains insufficiently understood. For instance, there is still no widely accepted method to assess SOM lability. Soil respiration tests and particulate organic matter (POM) obtained by different fractionation schemes have been used for decades and are now considered as classical estimates of very labile and labile soil organic carbon (SOC), respectively. But the pertinence of these methods to characterize SOM turnover can be questioned. Moreover, they are very time-consuming and their reproducibility might be an issue. Alternate ways of determining the labile SOC component are thus well-needed. Thermal analyses have been used to characterize SOM among which Rock-Eval 6 (RE6) analysis of soil has shown promising results in the determination of SOM biogeochemical stability (Gregorich et al., 2015; Barré et al., 2016). Using a large set of samples of French forest soils representing contrasted pedoclimatic conditions, including deep samples (up to 1 m depth), we compared different techniques used for SOM lability assessment. We explored whether results from soil respiration test (10-week laboratory incubations), SOM size-density fractionation and RE6 thermal analysis were comparable and how they were correlated. A set of 222 (respiration test and RE6), 103 (SOM fractionation and RE6) and 93 (respiration test, SOM fractionation and RE6) forest soils samples were respectively analyzed and compared. The comparison of the three methods (n = 93) using a principal component analysis separated samples from the surface (0-10 cm) and deep (40-80 cm) layers, highlighting a clear effect of depth on the short-term persistence of SOC. A correlation analysis demonstrated that, for these samples, the two classical methods of labile SOC determination (respiration and SOM fractionation

Structural Basis of Clostridium perfringens Toxin Complex Formation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adams,J.; Gregg, K.; Bayer, E.

2008-01-01

The virulent properties of the common human and livestock pathogen Clostridium perfringens are attributable to a formidable battery of toxins. Among these are a number of large and highly modular carbohydrate-active enzymes, including the {mu}-toxin and sialidases, whose catalytic properties are consistent with degradation of the mucosal layer of the human gut, glycosaminoglycans, and other cellular glycans found throughout the body. The conservation of noncatalytic ancillary modules among these enzymes suggests they make significant contributions to the overall functionality of the toxins. Here, we describe the structural basis of an ultra-tight interaction (Ka = 1.44 x 1011 M-1) between themore » X82 and dockerin modules, which are found throughout numerous C. perfringens carbohydrate-active enzymes. Extensive hydrogen-bonding and van der Waals contacts between the X82 and dockerin modules give rise to the observed high affinity. The {mu}-toxin dockerin module in this complex is positioned {approx}180 relative to the orientation of the dockerin modules on the cohesin module surface within cellulolytic complexes. These observations represent a unique property of these clostridial toxins whereby they can associate into large, noncovalent multitoxin complexes that allow potentiation of the activities of the individual toxins by combining complementary toxin specificities.« less

The role of labile sulfur compounds in thermochemical sulfate reduction

USGS Publications Warehouse

Amrani, A.; Zhang, T.; Ma, Q.; Ellis, G.S.; Tang, Y.

2008-01-01

The reduction of sulfate to sulfide coupled with the oxidation of hydrocarbons to carbon dioxide, commonly referred to as thermochemical sulfate reduction (TSR), is an important abiotic alteration process that most commonly occurs in hot carbonate petroleum reservoirs. In the present study we focus on the role that organic labile sulfur compounds play in increasing the rate of TSR. A series of gold-tube hydrous pyrolysis experiments were conducted with n-octane and CaSO4 in the presence of reduced sulfur (e.g. H2S, S??, organic S) at temperatures of 330 and 356 ??C under a constant confining pressure. The in-situ pH was buffered to 3.5 (???6.3 at room temperature) with talc and silica. For comparison, three types of oil with different total S and labile S contents were reacted under similar conditions. The results show that the initial presence of organic or inorganic sulfur compounds increases the rate of TSR. However, organic sulfur compounds, such as 1-pentanethiol or diethyldisulfide, were significantly more effective in increasing the rate of TSR than H2S or elemental sulfur (on a mole S basis). The increase in rate is achieved at relatively low concentrations of 1-pentanethiol, less than 1 wt% of the total n-octane, which is comparable to the concentration of organic S that is common in many oils (???0.3 wt%). We examined several potential reaction mechanisms to explain the observed reactivity of organic LSC. First, the release of H2S from the thermal degradation of thiols was discounted as an important mechanism due to the significantly greater reactivity of thiol compared to an equivalent amount of H2S. Second, we considered the generation of olefines in association with the elimination of H2S during thermal degradation of thiols because olefines are much more reactive than n-alkanes during TSR. In our experiments, olefines increased the rate of TSR, but were less effective than 1-pentanethiol and other organic LSC. Third, the thermal decomposition of

The role of labile sulfur compounds in thermochemical sulfate reduction

NASA Astrophysics Data System (ADS)

Amrani, Alon; Zhang, Tongwei; Ma, Qisheng; Ellis, Geoffrey S.; Tang, Yongchun

2008-06-01

The reduction of sulfate to sulfide coupled with the oxidation of hydrocarbons to carbon dioxide, commonly referred to as thermochemical sulfate reduction (TSR), is an important abiotic alteration process that most commonly occurs in hot carbonate petroleum reservoirs. In the present study we focus on the role that organic labile sulfur compounds play in increasing the rate of TSR. A series of gold-tube hydrous pyrolysis experiments were conducted with n-octane and CaSO4 in the presence of reduced sulfur (e.g. H2S, S°, organic S) at temperatures of 330 and 356 °C under a constant confining pressure. The in-situ pH was buffered to 3.5 (∼6.3 at room temperature) with talc and silica. For comparison, three types of oil with different total S and labile S contents were reacted under similar conditions. The results show that the initial presence of organic or inorganic sulfur compounds increases the rate of TSR. However, organic sulfur compounds, such as 1-pentanethiol or diethyldisulfide, were significantly more effective in increasing the rate of TSR than H2S or elemental sulfur (on a mole S basis). The increase in rate is achieved at relatively low concentrations of 1-pentanethiol, less than 1 wt% of the total n-octane, which is comparable to the concentration of organic S that is common in many oils (∼0.3 wt%). We examined several potential reaction mechanisms to explain the observed reactivity of organic LSC. First, the release of H2S from the thermal degradation of thiols was discounted as an important mechanism due to the significantly greater reactivity of thiol compared to an equivalent amount of H2S. Second, we considered the generation of olefines in association with the elimination of H2S during thermal degradation of thiols because olefines are much more reactive than n-alkanes during TSR. In our experiments, olefines increased the rate of TSR, but were less effective than 1-pentanethiol and other organic LSC. Third, the thermal decomposition of

Voltage-dependent blockade of muscle Na+ channels by guanidinium toxins

PubMed Central

1984-01-01

Na+ channels from rat muscle plasma membrane vesicles were inserted into neutral planar phospholipid bilayers and were activated by batrachotoxin. Single channel blocking events induced by the addition of various guanidinium toxins were analyzed to derive the rates of channel-toxin association and dissociation. Blocking by tetrodotoxin, saxitoxin, and six natural saxitoxin derivatives containing sulfate or hydroxyl groups were studied. Although the binding affinities vary over 2,000-fold, all of the toxins exhibit identical voltage dependence of the blocking reactions, regardless of the toxin's net charge. The results suggest that the voltage dependence of toxin binding is due to a voltage-dependent conformational equilibrium of the toxin receptor, rather than to direct entry of the charged toxin molecule into the applied transmembrane electric field. PMID:6096479

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

PubMed

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

2012-11-01

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 α(v)β(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. Copyright © 2012 Elsevier Ltd. All rights reserved.

Comparison of T-2 Toxin and HT-2 Toxin Distributed in the Skeletal System with That in Other Tissues of Rats by Acute Toxicity Test.

PubMed

Yu, Fang Fang; Lin, Xia Lu; Yang, Lei; Liu, Huan; Wang, Xi; Fang, Hua; Lammi, ZMikko J; Guo, Xiong

2017-11-01

Twelve healthy rats were divided into the T-2 toxin group receiving gavage of 1 mg/kg T-2 toxin and the control group receiving gavage of normal saline. Total relative concentrations of T-2 toxin and HT-2 toxin in the skeletal system (thighbone, knee joints, and costal cartilage) were significantly higher than those in the heart, liver, and kidneys (P < 0.05). The relative concentrations of T-2 toxin and HT-2 toxin in the skeletal system (thighbone and costal cartilage) were also significantly higher than those in the heart, liver, and kidneys. The rats administered T-2 toxin showed rapid metabolism compared with that in rats administered HT-2 toxin, and the metabolic conversion rates in the different tissues were 68.20%-90.70%. Copyright © 2017 The Editorial Board of Biomedical and Environmental Sciences. Published by China CDC. All rights reserved.

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. Copyright © 2014 Elsevier Ltd. All rights reserved.